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External circulation evaporator is also called external heat evaporator, its heater is directly placed on the outside of the evaporator, and the long diameter of the heating tube is relatively large, so the material liquid circulation flow rate is high. The external circulation evaporator is mainly applicable to the evaporation of the material liquid with large concentration, large viscosity and easy to be scaled and coked. This kind of evaporator in chemical industry, medicine, food and other industries have application. Due to the material liquid in the tube liquid column is higher, improve the lower part of the liquid The boiling point of the body, so the heating error is required to be larger, limiting the use of multi-effect. This evaporator raw steam (primary steam) heating temperature are higher. 1, feed: the liquid to be treated feed into the evaporator. 2, evaporation: in the external circulation evaporator, to be treated liquid from the feed pipe into a heater, and then be heated, so that part of it into a vapor state. 3.Condensation: The vapor passes through the condenser inside the evaporator, which is usually a tube bundle or heat exchanger, in which the cooling medium is transferred to condense the vapor into liquid. 4.Separation: Inside the evaporator, liquid and vapor are separated by a separation device. Commonly used separation devices include gravity separators, centrifuges and cartridges. 5.Recirculation: The separated liquid is recirculated inside the evaporator. Usually, part of the liquid will flow back to the bottom of the evaporator through a return tube to maintain the stable work of the evaporator. 6.Vapor discharge: The vapor that is not condensed is discharged from the evaporator through an exhaust port to enter the subsequent treatment or recycling. Throughout the process, the external circulation evaporator through the heater to heat the liquid to its boiling point above, so that part of it into steam, and then through the condenser and separation device to separate the steam and liquid, and finally the remaining steam discharge. This method can realize the separation and concentration of the liquid, and at the same time achieve the purpose of energy recycling and environmental protection. The characteristics of external circulation evaporator are as follows: 1.Heating unit is placed outside the evaporator, which is convenient for maintenance and cleaning. 2.The common specifications of heating tube diameter are ϕ19mm×2mm, ϕ25mm×2mm and ϕ32mm×2mm. 3.Heating tube length-to-diameter ratio can be 50~100, easy to get a high liquid circulation flow rate. 4.The circulating flow rate of material liquid can reach 1.5~2.0m/s, which is convenient to get high heat transfer coefficient. 5, the heat transfer coefficient is usually between 1200 ~ 3500W / (m2 - ℃). 6, the completion of the liquid and secondary steam separation of the vast majority of the separation chamber is realized in the separation chamber, the separation chamber volume is large, the inlet is tangential design, and need to be set up to capture the foam device. 7, the separation chamber of the secondary steam discharge pipe to be inserted into the separation chamber, usually 150 ~ 250mm, which can play the role of cyclone, conducive to further separation of steam and liquid. 8, out of the separation chamber of the secondary steam can be baffled or cyclone type foam trapping device to further separate the entrainment of liquid droplets, and then into the condenser. 9.Outside circulation evaporator can be set into multi-effect form. Source:Reprint Disclaimer: This article is a network reproduced, the copyright belongs to the original author. If it involves copyright issues, please contact us, we will remove the content at the first time.

We know that a distillation tower generally consists of a tower kettle, tower section, condenser, discharge pipeline, output pipeline, reflux pipeline, etc. Why do we need a return line? Let's first talk about the main role of reflux in distillation towers: Firstly, provide cold reflux on the tray to remove excess heat inside the tower and maintain heat balance inside the tower; Secondly, provide a cold fluid on the tray, where the gas-liquid phases come into reverse contact. The heavy components in the upward gas condense, while the light components in the downward liquid absorb heat and vaporize. This repeated condensation and vaporization process fills the entire tower section with light components The components, the lower part is the recombinant component, further improving the separation purity of the product. Therefore, reflux liquid is a necessary condition for distillation purification. 1. Common reflux methods in distillation operations Firstly, according to the different reflux methods, it can be divided into "natural reflux" and "forced reflux". Natural reflux refers to the condenser of the tower located above the distillation tower section, with a certain height. The liquid storage outlet of the condenser is higher than the reflux outlet of the tower section and has a certain distance. The reflux liquid flows back into the tower under the action of gravity. Natural reflux operation is simple and does not require a reflux pump, saving power consumption. However, the reflux rate varies with the pressure inside the tower, and the reflux ratio is not strict. When production is abnormal, the adjustment is relatively slow. Natural reflux is widely used in small distillation units, requiring sufficient height and space. Forced reflux is the installation of a pump on the reflux pipeline, and the reflux liquid is pumped into the tower for reflux. The reflux flow rate of forced reflux is stable and easy to adjust. When production is abnormal, it can be adjusted quickly. However, forced reflux requires a pump, which consumes a lot of power, especially for low boiling materials, which can cause pump failure and affect operation. However, the condenser with forced reflux is not limited by height and can be installed in a convenient location for installation and maintenance. Secondly, according to the different installation positions of condensation at the top of the tower, it can be divided into internal reflux and external reflux. Internal reflux refers to the vertical connection between the condenser and the tower section, located directly above the tower section. In distillation, internal reflux generally refers to the reflux on the tray, which is composed of the liquid produced by the condensation of the descending liquid and the rising gas. The auxiliary condensing equipment of the distillation tower includes a splitter, a total condenser, and a condenser. The top of the tower can be designed with a condenser. The gas phase at the top of the tower passes through the condenser, and a portion of the condensation directly flows back into the tower, which is called internal reflux. The remaining gas with condensation enters another condenser for condensation. A full condenser can also be installed at the top of the tower, with a receiving tray set below the full condenser. Part of it is extracted, while the other part flows back, which is also called internal reflux. Under normal circumstances, high boiling points and high toxicity should be treated with this internal reflux method. Directly entering the condenser from the top of the tower, partial condensation is carried out here, and the condensate naturally flows down the tray. The amount of reflux is difficult to control and cannot be accurately adjusted. Due to the influence of heating, the reflux rate varies greatly. However, this reflux condenser is directly installed at the top of the tower and does not require any other supporting structures, making installation convenient. The external reflux in distillation is to extract a portion of liquid from the tower section, cool it down, and then pour it into the tower. The condenser at the top of the tower is installed separately, and a sight glass, flow meter, regulating valve, etc. can be installed on the reflux pipeline to adjust the amount of reflux. 2. The difference between internal reflux and external reflux Internal reflux refers to the material not leaving the top of the tower, but directly flowing back into the distillation tower after condensation at the top. Measurement is difficult, and the ratio of fractionation and reflux cannot be accurately determined. It is a direct return to the tower after gas-phase condensation at the top of the reflux tower. During operation, attention should be paid to controlling the extraction amount to prevent product failure. Although the internal reflux lacks a reflux pump, a reflux distributor should be installed between the condenser and the top of the tower, It is generally required to have a rotating or moving device to distribute the reflux ratio, and facilities that rely on electric motors or other power drives are not suitable for enclosed installation in the tower. This regulation is "graded" and is a non-standard equipment. External reflux refers to the material leaving the top of the tower, passing through external pipelines, flow meters, etc., and then flowing back into the distillation tower. It can be metered for diversion or forced reflux. After the gas phase at the top of the tower condenses and enters the reflux tank, it is adjusted by the reflux pump control valve and flow meter The flow returns to the tower. Most distillation towers in industry use external reflux, which can automatically and steplessly adjust the reflux rate to meet production needs, especially when there are fluctuations in feed volume or composition. 3. Application of external and internal reflux External reflux is beneficial for controlling process flow and temperature, with high operating costs and no utilization of liquid potential energy, resulting in high costs. If the condenser at the top of the tower cannot meet the condensation requirements, a forced condensation reflux system can be added to achieve forced operation of the distillation tower. In addition, the relative size of operating costs and infrastructure investment costs also needs to be considered when investing. If the metering requirements for the reflux liquid are not high or the operating flexibility of the reflux ratio is large, internal reflux can be used. If an online flow measurement instrument can be developed along the internal reflux route, internal reflux can be achieved, and distillation is generally referred to as external reflux. The advantage of external reflux is that it is easy to adjust, but it increases operating costs and increases leakage points. It may not be suitable for some high-risk media, and internal reflux is preferred for high-risk media that are not too high in the tower. So the choice of reflux method should be comprehensively considered from multiple aspects. According to the temperature of reflux, it can be divided into "hot reflux" and "cold reflux". Hot reflux refers to the temperature of the reflux liquid being at the bubble point temperature, while cold reflux refers to the temperature of the reflux liquid being below the bubble point temperature. The reflux of a distillation tower is generally saturated liquid reflux, which is to ensure the stable working state of the distillation section and slightly undercooled reflux of the reflux liquid. The theoretical reflux ratio can be increased without increasing the reflux flow rate, because the reflux liquid entering the distillation section will cause a large amount of condensation of the rising steam, improving the purity of the top output while ensuring the quantity of top output. However, one downside is to increase the heat load of the tower kettle, The heat consumption is relatively high, and if the output added value is high, it is still economically reasonable and much more cost-effective than reflux of saturated liquids. For distillation units with a full condenser, most industrial reflux uses cold reflux mainly because: 1. The top gas phase of the tower can achieve complete condensation during the condensation process, reducing the loss of gas phase emissions. 2. It is difficult to control the top temperature of a fully condensed tower in a saturated liquid state. 3. Slightly undercooling reflux can increase the theoretical reflux ratio without increasing the reflux flow rate. Total reflux is the operation in which the condensate extracted from the top of the tower is returned to the distillation kettle as reflux liquid. Total reflux is a necessary process during start-up to ensure that the product is qualified as soon as possible. In normal production, total reflux cannot be carried out arbitrarily unless there are process fluctuations, as the distillation tower loses its meaning of existence without product extraction. If waiting for the analysis results of the product to clean the entire tower, total reflux can be used. 4. How to control reflux during distillation operation? There are generally two types of tower top reflux control: manual control and automatic control. When manually controlling the distillation operation, as long as there is no significant change in the quality of the product at the top of the tower, the change in the reflux rate of the tower is very small, and can even remain unchanged. In actual operation, the reflux rate is basically not affected by the feed amount. The reflux tank liquid level should be maintained, and there should be no phenomenon of full or empty tanks. Experienced operators should control the reflux rate according to the actual situation of the tower and adjust the efficiency of the tower. During automatic control, the reflux rate is affected by the amount of material extracted from the top of the tower. When the feed rate remains constant, it is necessary to control the amount of material extracted from the top of the tower. As the amount of material extracted from the top of the tower increases, the reflux ratio decreases, the gas-liquid contact is poor, and the quality of the product at the top of the tower is unqualified. If the feeding amount increases, the amount of increase in top extraction should be calculated. If the extraction is too small, the reflux rate increases, the material inside the tower increases, the rising steam speed increases, and the pressure difference between the top and bottom of the tower increases. In severe cases, it can cause liquid flooding. If the extraction amount is too large, the reflux rate decreases, the gas-liquid contact is poor, and the quality of the output at the top of the tower is unqualified. Generally, an automatic reflux device should be installed in a distillation tower, and the main discharge pipeline and output pipeline should also be equipped with self-control, with a fixed reflux ratio. All three must be changed simultaneously to ensure the normal operation of the entire distillation tower. Source: Reproduction Disclaimers This article is reproduced online, and the copyright belongs to the original author. If there are copyright issues, please contact us and we will delete the content as soon as possible.

Thin film evaporator is a type of evaporator, characterized by material flowing in a film like manner along the heating tube wall for heat transfer and evaporation. It has high heat transfer efficiency, fast evaporation speed, and short material residence time, making it suitable for the evaporation of heat sensitive substances. According to the reasons for film formation and flow direction, it can be divided into three types: rising film evaporator, falling film evaporator, and scraping film evaporator. Below are the steps, applications, and efficiency improvement measures for using thin film evaporators. Steps for using a thin film evaporator 1. Preparation before driving (1) General products have undergone water pressure testing and trial operation before leaving the factory, and the indicators meet the requirements. (2) Start the motor and observe if the direction of operation is correct. It should rotate clockwise and not reverse. (3) Measure whether the radial swing and axial string momentum of the shaft meet the requirements, and check whether the sealing is tightly sealed. (4) Whether the oil level of the gearbox is in a normal state and whether the cooling water of the mechanical seal is kept unobstructed. 2. Normal driving (1) Turn on the circulating cooling water pump and put the condenser in operation. Then open the concentrated solution container and vacuum the valve. (2) Open the feed valve and pump in the feed liquid. Connect the power, start the motor, and observe if the direction of rotation of the motor is correct. (3) Slowly open the steam valve and connect the steam trap, so that the steam pressure is around 0.15MPa. (4) Observe the discharge of the evaporator and wait for the equipment to run stably for 5 minutes before sampling and analyzing the concentration of the concentrated solution. If the concentration does not meet the standard, make adjustments. When the liquid level of the concentrated solution container is about to be full, switch to another option and follow the steps to switch. 3. The sequence of normal parking is as follows: close the steam valve - close the feed valve - after the material is drained, close the discharge valve - flush the equipment - stop the motor - stop the circulating water pump and jet pump - open the vacuum breaking valve. 4. Safety precautions (1) Do not start the motor for stirring when there is no liquid or when the liquid is full. (2) The motor is strictly prohibited from running in reverse. During operation, do not touch the rotating parts with your hands. (3) Do not press the button with wet hands to prevent electric shock. The application of thin film evaporators Thin film evaporators have the characteristics of high production efficiency, large production capacity, and short heating time of materials, and can be widely used for the concentration of dilute solutions of various chemical materials. Scraper type thin film evaporator is an efficient evaporation and distillation equipment that mainly uses high rotation to distribute liquid into a uniform thin film for evaporation or distillation. At the same time, the scraper film evaporator can also be used for deodorization, defoaming reactions, heating, cooling and other unit operations. Currently, this device has been widely used in industries such as Chinese and Western pharmaceuticals, food, light industry, petroleum, chemical, environmental protection, etc. Especially, this equipment can be used to treat materials with high concentration, high viscosity, thermal sensitivity, and easy scaling characteristics. How to improve the efficiency of thin film evaporators 1. Choose the appropriate working pressure and temperature: The operating efficiency of the evaporator is related to temperature and pressure, and it is necessary to choose the appropriate working pressure and temperature to ensure that the efficiency of the evaporator reaches its maximum. 2. Control of feed quantity and quality: The control of feed quantity and quality directly affects the operational efficiency of the evaporator. The operational efficiency of the evaporator should be improved by controlling the feed flow rate and quality. 3. Strengthen the cleaning of heat exchangers: The heat exchanger of the evaporator may produce a large amount of scale during long-term operation, leading to a decrease in heat exchange efficiency. Regular cleaning of the heat exchanger should be carried out to ensure the heat exchange efficiency of the evaporator. In addition, the following details can be optimized: 1. Reducing the operating speed of the scraper film evaporator steam compressor reduces the flow rate, avoiding the compressor from surging state. However, the outlet pressure of the steam compressor will also decrease accordingly, and adjustable blades can be used. 2. Check the connection parts of each component of the entire evaporator for any leaks, and replace the gaskets and other sealing components at the flange connection in a timely and regular manner. 3. Regularly clean the evaporator and choose a suitable cleaning cycle based on the scale formation in the evaporation system. If the scale formation in the evaporation system is severe, try to shorten the cleaning cycle as much as possible. 4. When the temperature of the cooling water in the evaporation system is too high, it can cause the steam to not condense in time and reduce the vacuum degree of the system. It is necessary to regularly supplement cold water to the circulating water pool to maintain a stable temperature of the cooling water. 5. The fouling and heat transfer efficiency of the condenser in the scraper film evaporator decreases, causing the steam to not condense in time and reducing the vacuum degree. Therefore, it is necessary to regularly inspect and clean the condenser. Source: Reproduction Disclaimer: This article is reproduced online, and the copyright belongs to the original author. If there are copyright issues, please contact us and we will delete the content as soon as possible.

Overview Heat exchangers, as heat transfer equipment that transfers part of the heat from the hot fluid between materials to the cold fluid, have a wide range of applications in people's daily lives and industries such as petroleum, chemical, power, medicine, atomic energy, and nuclear industry. It can serve as an independent device, such as a heater, condenser, cooler, etc; It can also be used as a component of certain process equipment, such as heat exchangers in some chemical equipment. Especially in the chemical industry with high energy consumption, heat exchangers are indispensable equipment in the heat exchange and transfer process of chemical production, and they also occupy a considerable proportion in the entire chemical production equipment. From the perspective of its function, heat exchangers are not only responsible for ensuring the specific temperature required by industrial processes for the medium, but also the main equipment for improving energy utilization efficiency. According to their structural forms, there are mainly plate heat exchangers, floating head heat exchangers, and fixed tube plates Type heat exchangers and U-tube heat exchangers, etc. Except for plate heat exchangers, the other types belong to shell and tube heat exchangers. Due to its large heat exchange area per unit volume, good heat exchange efficiency, and advantages such as sturdy structure, strong adaptability, and mature manufacturing process, shell and tube heat exchangers have become the most commonly used typical heat exchanger. Connection between heat exchange tubes and tube sheets in shell and tube heat exchangers In a shell and tube heat exchanger, the heat exchange tube and tube plate are the only barriers between the tube and shell sides of the heat exchanger. The connection structure and quality between the heat exchange tube and tube plate determine the quality and service life of the heat exchanger, which is a crucial link in the manufacturing process of the heat exchanger. The damage and failure of most heat exchangers occur at the connection between the heat exchange tubes and tube sheets, and the quality of the connection joints directly affects the safety and reliability of chemical equipment and devices. Therefore, the connection process between the heat exchange tubes and tube sheets in shell and tube heat exchangers is crucial It has become the most critical control link in the quality assurance system of heat exchanger manufacturing. At present, in the manufacturing process of heat exchangers, the connection between heat exchange tubes and tube sheets mainly includes welding, expansion joint, expansion joint with welding, and adhesive joint with expansion joint. 1. Welding When the heat exchange tube and tube plate are connected by welding, due to the low requirements for tube plate processing, simple manufacturing process, good sealing, and convenient welding, appearance inspection, and maintenance, it is currently the application of connecting heat exchange tubes and tube plates in shell and tube heat exchangers The most widely used method of connection. When using welding connections, there is strength welding that ensures the sealing and tensile strength of the welded joint, and sealing welding that only ensures the sealing of the heat exchange tube and tube plate connection. For strength welding, its performance is limited and only suitable for Used in situations with low vibration and no gap corrosion. When using welding connections, the distance between heat exchange tubes should not be too close, otherwise it will be affected by heat and the quality of the weld seam will not be easily guaranteed. At the same time, a certain distance should be left at the tube ends to reduce welding stress between them. The length of the heat exchange tube protruding from the tube plate must meet the requirements The specified requirements are required to ensure its effective bearing capacity. In terms of welding methods, welding can be carried out using methods such as electrode arc welding, TIG welding, CO2 welding, etc. based on the material of the heat exchange tube and tube plate. For heat exchangers with high requirements for the connection between heat exchange tubes and tube sheets, such as those with high design pressure, high design temperature, large temperature changes, and those that withstand alternating loads, thin tube sheet heat exchangers, etc., TIG welding is recommended. The conventional welding connection method, due to the gap between the pipe and the tube plate hole, is prone to gap corrosion and overheating, and the thermal stress generated at the welding joint may also cause stress corrosion and damage, which can lead to the failure of the heat exchanger. Currently in China In heat exchangers used in industries such as nuclear and power industries, the connection between heat exchange tubes and tube sheets has begun to use inner hole welding technology. This connection method changes the end welding of heat exchange tubes and tube sheets to inner hole welding of tube bundles, using a full penetration form, eliminating the need for internal hole welding The gap welded at the end enhances the ability to resist gap corrosion and stress corrosion, Its anti vibration fatigue strength is high, it can withstand high temperature and high pressure, and the mechanical properties of welded joints are good; Internal non-destructive testing can be performed on the joint, and the internal quality of the weld can be controlled, improving the reliability of the weld. But the assembly of inner hole welding technology is difficult, High requirements for welding technology, complex manufacturing and inspection, and relatively high manufacturing costs. With the development of heat exchangers towards high temperature, high pressure, and large-scale, the requirements for their manufacturing quality are becoming increasingly high, and the inner hole welding technology will be more widely used. 2. Expansion joint Expansion joint is a traditional method of connecting heat exchange tubes and tube sheets, which uses expansion instruments to cause elastic-plastic deformation between the tube sheets and tubes, forming a firm connection and achieving the goal of both sealing and anti pulling. During the manufacturing process of heat exchangers, expansion occurs Suitable for situations without severe vibration, significant temperature changes, and severe stress corrosion. The current expansion joint processes mainly include mechanical rolling and hydraulic expansion. Uneven mechanical rolling and expansion joints make it very difficult to repair them with expansion pipes once the connection between the pipe and the tube plate fails; Adopting liquid bag hydraulic expansion joint controlled by computer, with high accuracy and the ability to Ensure that the tightness of the expansion joint is uniform and consistent, and the reliability of the connection is better than that of mechanical expansion joint. However, strict requirements are placed on machining accuracy, and it is also difficult to ensure successful expansion of densely packed joints. If they fail, it is also difficult to repair them through expansion. 3. Expansion joint and welding When the temperature and pressure are high, and under the action of thermal deformation, thermal shock, thermal corrosion, and fluid pressure, the connection between the heat exchange tube and the tube plate is extremely easy to be damaged, and using expansion or welding is difficult to ensure the requirements of connection strength and sealing. Currently widely adopted It is a method of expansion welding combined with other methods. The expansion joint and welding structure can effectively damp the damage of tube bundle vibration to the weld seam, eliminate stress corrosion and gap corrosion, improve the fatigue resistance of the joint, and thus improve the service life of the heat exchanger Simple expansion or strength welding has higher strength and sealing performance. For ordinary heat exchangers, the form of "adhesive expansion% strength welding" is usually adopted; However, heat exchangers with strict usage conditions require the use of "strength expansion%" The form of seal welding. Expansion and welding can be divided into two types according to the order of expansion and welding in the process: first expansion and then welding, and first welding and then expansion. (1) The lubricating oil used during the first expansion and then welding expansion joint will penetrate into the joint gap, and they have strong sensitivity to welding cracks, pores, etc., which makes the phenomenon of defects during welding more serious. These oil stains that penetrate into the gaps are difficult to remove Clean, so the process of first expanding and then welding is adopted, and mechanical expansion joint is not suitable. Although the use of adhesive expansion is not pressure resistant, it can eliminate the gap between the pipe and the pipe plate hole, so it can effectively damping the vibration of the pipe bundle to the welding part of the pipe mouth. However, conventional manual or mechanically controlled expansion methods cannot achieve uniform expansion requirements, while the liquid bag expansion method with computer-controlled expansion pressure can conveniently and uniformly achieve expansion requirements. During welding, due to the high temperature melting of the metal The impact is that the gas inside the gap is heated and rapidly expands, causing certain damage to the sealing performance of the strength expansion when these gases with high temperature and pressure leak out. (2) For the welding followed by expansion process, the primary issue is to control the accuracy and fit of the pipe and tube plate holes. When the gap between the tube and the tube plate hole is reduced to a certain value, the expansion process will not damage the quality of the welded joint. But the welded joint bearing The ability to withstand shear force is relatively poor, so if the control during strength welding does not meet the requirements, it may cause over expansion failure or damage to the welded joint due to expansion. During the manufacturing process, there is a significant gap between the outer diameter of the heat exchange tube and the tube plate hole, and the gap between the outer diameter of each heat exchange tube and the tube plate hole is uneven along the axial direction. When expanding after welding is completed, the centerline of the pipe must be aligned with the center of the pipe plate hole The overlapping of lines is necessary to ensure the quality of the joint. If the gap is large, due to the high rigidity of the pipe, excessive expansion deformation will cause damage to the welded joint, and even lead to weld detachment. 4. Adhesive and expansion joints The use of adhesive and expansion joint processes helps to solve the common problems of leakage and leakage at the connection between heat exchange tubes and tube sheets in heat exchangers. It is important to select the appropriate adhesive according to the working conditions of the bonded parts. In the process of process implementation, heat exchange should be combined The structure and size of the device should be selected with good process parameters, mainly including curing pressure, curing temperature, swelling force, etc., and strictly controlled during the production process. This process is simple, easy to implement, and reliable, and has been recognized in practical use by enterprises. It has Promotion value. Conclusion (1) In the connection method between heat exchange tubes and tube sheets in shell and tube heat exchangers, conventional welding or expansion alone is difficult to ensure the connection strength and sealing requirements. (2) The use of expansion joint and welding method is conducive to ensuring the connection strength and sealing between the heat exchange tube and the tube plate, and improving the service life of the heat exchanger. (3) The method of using adhesive and expansion joints helps to solve the problems of leakage and leakage when connecting heat exchange tubes and tube sheets, and the process is simple, feasible, and reliable. (4) Inner hole welding technology, as a fully penetrated welding method, has excellent resistance to gap corrosion and stress corrosion, vibration fatigue strength, and mechanical properties of welded joints; The internal quality of the weld can be controlled, improving the reliability of the weld Sex is more suitable for promotion and application in high-end products. Source: Reproduction Disclaimer: This article is reproduced online, and the copyright belongs to the original author. If there are copyright issues, please contact us and we will delete the content as soon as possible.

Bending methods There are a variety of methods of pipe bending, generally manual bending and mechanical bending. Mechanical bending methods and a variety of methods, such as pressure bending method, roll bending method, back bending method and squeeze bending method. Regardless of which bending method, the main contradiction in the entire bending process are such as How to overcome the problem of local deformation. The most widely used in the project is the manual bending and bending back to the pipe bending process. Back bending method is in the rotary pipe bender bending, it can be divided into two types of mold bending and mold bending. Hand bending Manual bending does not require special equipment and complex process equipment, it can bend a variety of radii, angles and space towards the bend. But this bending mode of labor intensity, low productivity, quality is not stable enough. Manual bending of steel pipe using hot bending, for stainless steel and non-ferrous metals should be used for cold bending. Before bending in the tube first filled with filler, steel pipe filler is generally pure, dry fine sand, stainless steel and non-ferrous metal filler should be used rosin, lead and other low melting point materials Quality, in order to prevent wrinkles, and reduce the degree of ovalization Mold bending This category of pipe bender are using mold bending. The main mold has a disc-shaped grooved wheel and ram's horn core head of two kinds. Disc-shaped groove wheel bending pipe bending mold on the outside of the pipe, half of the pipe lying in the groove, the other half of the pipe bending area with a small groove roller (also known as compression roller) pressed. Roller (also known as compression rollers) pressed. Tube end is fixed by the chuck on the disc-shaped bending die, if the pressure roller does not move, disc-shaped bending die active rotation to complete the bend, known as pull bending; if the tube is pushed to make the disc-shaped bending die rotate to complete the bending of the passive, known as the push bending Type; if the disc-shaped bending mold does not move, the compression roller pressed the tube around the disc-shaped bending mold rotation to complete the bend, known as pressure bending. Sheep's horn mandrel bending tube when the bending mold in the tube on the inside, sheep's horn mandrel like sheep's horns, the axis of the length of 1/4 circumference, the bending radius and the same bending tube, the maximum bending angle of 180 °. Sheep's horns core head thin end than the inner diameter of the billet is slightly thin, the billet from the thin end of the set into the thick end is out of the Outlet, slightly thicker than the inner diameter of the billet. Bend the billet is first heated and then set into the mold, the tube under the action of the thrust of the two processes of bending and expansion, sliding out of the end of the core head when the bending process. Mold bending This bending method of pipe bending machine used without a special decision to bend a certain bending radius of the bending mold. It can be divided into two types of bending and push bending. Bender has a rotating arm, arm length can be retracted, when the pipe is fixed in the rotating arm, the central axis of the pipe to the rotating arm The distance between the center axis of the pipe and the center of rotation of the arm is the bending radius. At work, the tube is covered with a copper induction loop, induction loop through the medium frequency (for thicker tubes) or high frequency (for thin tubes) electricity will be partially heated to 900 ~ 950 ℃, and then bent. If the rotary arm active Rotating the tube back to the bend forming known as the pull-bend type; if the end of the tube by the thrust, the tube to push the rotary arm to rotate, thereby realizing the tube back to the bend forming known as the push-bend type. Immediately after the inductor ring from the inside of a circle of small holes to the bent pipe section spray water, so that it cools quickly. The purpose of spraying water is to make the heating section and the deformation zone is limited to a very small range, thus preventing the tube from wrinkles and flattening. Source: Reprint Disclaimer: This article is reproduced on the Internet, and the copyright belongs to the original author. If it involves copyright issues, please contact us, we will remove the content at the first time!

According to the different ways of solid precipitation, crystallization can be divided into various types such as solution crystallization, melt crystallization, sublimation crystallization, and precipitation crystallization. The most widely used method in industry is solution crystallization, which is achieved by cooling or removing solvents to achieve a solution that In a saturated state, precipitate solutes as products. In addition, crystallization operations can also be divided into intermittent and continuous based on whether the operation is continuous, or into stirred and non stirred based on the presence or absence of a stirring device. 1. Method of solution crystallization Solution crystallization refers to the process in which crystals precipitate from a solution. The basic condition for solution crystallization is the supersaturation of the solution, which generally goes through the following process: unsaturated solution → saturated solution → supersaturated solution → formation of crystal nuclei → crystal growth. 1. Cooling method Cooling method, also known as cooling method, is a method of achieving supersaturation of a solution by cooling down. Cooling crystallization basically does not remove the solvent, but reduces the temperature by removing the heat from the solution, allowing the solution to reach a supersaturated state and proceed with crystallization. This method Suitable for situations where solubility significantly decreases with decreasing temperature. Cooling can be divided into natural cooling, wall cooling, and direct contact cooling. The natural cooling method is to cool and crystallize a solution in the atmosphere, and its equipment structure and operation are the simplest, but the cooling rate is the same Slow, low production capacity, and difficult to control crystal quality. Wall cooling method is a widely used crystallization method in industry, which relies on indirect heat transfer and cooling of crystallization through jackets or tube walls. This method consumes less energy and is widely used, but the cooling heat transfer rate is low and cold However, crystals often precipitate on the wall surface, forming crystal scale or scars on the device wall, which affects the cooling effect. Direct contact with the cooler to cool with air or refrigerant in direct contact with the solution. This method overcomes the drawbacks of wall cooling, has high heat transfer efficiency, and is not complicated Scar problem, but the equipment is bulky; When using this operation, it is important to note that the selected cooling medium should not be miscible with the solvent in the crystallization mother liquor or, although miscible, should be easy to separate and not contaminate the crystallization product. 2. Evaporation method The evaporation method is a method of crystallization that achieves supersaturation of a solution by removing some solvents, and is suitable for situations where solubility does not change significantly with temperature. Evaporative crystallization consumes more energy and also has the problem of easy scaling on the heating surface, but it is not conducive to The crystallization process of solvent recovery is still cost-effective. Evaporative crystallization equipment is often operated under low vacuum pressure in order to lower the operating temperature, facilitate the stability of thermosensitive products, and reduce thermal energy loss. 3. Vacuum cooling method Vacuum cooling method, also known as flash cooling crystallization method. It is a crystallization method in which a solvent undergoes flash evaporation under vacuum conditions to adiabatic cool the solution. Essentially, it combines cooling and evaporation methods simultaneously. This method is applicable as the temperature rises Substances with high solubility that increase at a moderate rate, such as ammonium sulfate, potassium chloride, etc. The main equipment of this method is simple, without heat exchange walls, with fewer crystal scars, and can take a longer maintenance time. The corrosion prevention problem of the equipment is also easy to solve, making it the first choice in large-scale crystallization production Method. 4. Salt precipitation method The salt precipitation method is a method of establishing supersaturation for crystallization by adding a certain substance to the solution to reduce the solubility of the solute in the solvent. The added substance is called a salt precipitation agent or precipitant, and it is required to be miscible with the original solvent, but not soluble The substance to be crystallized requires easy separation between the added substance and the original solvent. The reason why it is called salt precipitation method is because sodium chloride is the most common additive. For example, in the combined alkali production method, adding sodium chloride to a low-temperature ammonium chloride solution can make the solution The ammonium chloride crystallized out. Water, alcohols, and ketones can also be used as additives to cause salt crystallization in certain solutions, sometimes also known as solution crystallization. The salt precipitation process is simple and easy to operate, suitable for the crystallization of thermosensitive materials and drug crystallization; The disadvantage is that it often requires Set up recycling equipment to process crystallization mother liquor, in order to recover solvents and salt precipitation agents. 5. Reactive crystallization Reaction crystallization is the use of chemical reactions between gases and liquids or liquids and liquids to produce products with low solubility. This situation is a combination of reaction and crystallization processes. As the reaction progresses, the concentration of reaction products increases and reaches supersaturation In solution, crystal nuclei are generated and gradually grow into larger crystal particles. In addition, there are pressure crystallization and isoelectric point crystallization methods that reduce solubility by changing pressure or controlling pH. 2. Crystallizer There are many types of crystallizers, which can be divided into cooling crystallizers and evaporating crystallizers according to the method of obtaining saturation state of the solution; According to the flow mode, it can be divided into mixed slurry crystallizer, graded crystallizer, mother liquor circulation crystallizer, and slurry circulation crystallizer; By Yes Non stirred crystallizers are divided into stirred crystallizers and non stirred crystallizers; According to the operation mode, it can be divided into continuous crystallizer and intermittent crystallizer. 1. Cooling crystallizer 1) Air cooled crystallizer Air cooled crystallizer is the simplest open crystallization tank, which cools in the atmosphere and gradually lowers the temperature in the tank, while a small amount of solvent vaporizes. Due to the intermittent operation and slow cooling, salts containing polycrystalline water often High quality and large crystals can be obtained. But it occupies a large area and has low production capacity. 2) Kettle crystallizer The cooling required for the crystallization process is supplied by a jacket or an external heat exchanger, and the choice of crystallizer mainly depends on the demand for heat exchange capacity. Currently, the widely used ones include internal circulation cooling crystallizers with stirring and external circulation cooling crystallizers Device, as shown in the following figure. The external circulation cooling crystallizer can be operated intermittently or continuously. If producing large particle crystals, intermittent operation is recommended, while continuous operation is better for preparing small particle crystals. External loop operation can strengthen the structure The uniform mixing and heat transfer inside the crystal have the advantages of a large cooling heat exchanger area and a high heat transfer rate, which is conducive to the control of solution supersaturation. However, it is necessary to choose a suitable circulation pump to avoid the wear and breakage of suspended particle crystals. 2. Evaporative crystallizer 1) Krystal Olso growth type evaporative crystallizer Krystal Olso growth type (forced circulation type) evaporative crystallizer, which consists of an evaporation chamber and a crystallization chamber. The evaporation chamber is located above and the crystallization chamber is located below, connected by a central downcomer in the middle. The body of the crystallization chamber is equipped with A certain taper, with a small lower section and a larger upper section. After the raw material liquid is preheated by an external heater, it enters the evaporation chamber through a recirculation tube and is quickly evaporated. The solvent is extracted and the solution is cooled, causing the solution to quickly enter the metastable zone and precipitate in the crystallization chamber Produce crystals. Larger crystal particles are enriched at the bottom of the crystallization chamber, and the supersaturation of the solution flowing out of the downcomer gradually decreases. When the solution reaches the top layer of the crystallization chamber, there are basically no grains left, and the supersaturation is completely consumed. The clear mother liquor crystallizes The overflow from the top of the room enters the circulation pipeline. This operation method is a typical mother liquor circulation type, which has the advantage that the circulating liquid basically does not contain crystal particles, thereby avoiding excessive secondary nucleation caused by collision between the pump impeller and the grains, as well as crystallization The particle size grading effect of the room produces crystalline products with large and uniform particles. The disadvantage of this crystallizer is its low operating flexibility, limited circulation of mother liquor by the settling speed of product particles in saturated solution, and easy formation of the inner wall surface of the heating tube in the crystallizer Crystal scale causes a decrease in the heat transfer coefficient of the heat exchanger 2) DTB type evaporative crystallizer DTB type (also known as shielded type) evaporative crystallizer. It can be used in conjunction with evaporative heaters or separated from heaters. The crystallizer is currently the most commonly used type as a vacuum evaporative cooling crystallizer. Its characteristic is steaming There is a guide tube in the generator room, which is equipped with a stirrer with a propeller. It quickly pushes the saturated solution with small crystals to the evaporation surface. Due to the vacuum state of the system, the solvent produces flash evaporation, resulting in mild supersaturation, and then When a saturated solution flows downwards along the annular area, its supersaturation is released, allowing the crystal to grow. There is a grading leg at the bottom of the device, and the extracted product slurry needs to pass through it first, mix with the raw material liquid, and then circulate through the central guide pipe. Crystal growth After reaching a certain size, it precipitates in the grading legs, and the product is also washed. Finally, it is separated outside the crystal slurry pump to ensure the quality and uniform particle size of the crystalline product, so that the product is not mixed with fine crystals. DTB type crystallizer is a typical slurry internal circulation crystallizer with excellent performance, high production intensity, and the ability to produce large particle crystalline products. It is not easy to scale inside the crystallizer and has become one of the main forms of continuous crystallizer, which can be used for vacuum cooling and evaporation methods Crystallization and reaction crystallization operations. Source: Reproduction Disclaimer: This article is reproduced online, and the copyright belongs to the original author. If there are copyright issues, please contact us and we will delete the content as soon as possible.

Thin film evaporator is a type of evaporator, which is characterized by heat transfer and evaporation of materials along the wall of the heating tube as a membrane flow, high heat transfer efficiency, fast evaporation speed, short residence time of materials, suitable for the evaporation of heat-sensitive substances. According to the reason and flow direction of the film, can be divided into three types: ascending film evaporator, descending film evaporator, scraping film evaporator. The following introduces the film evaporator use step, application, improve efficiency measures. Thin film evaporator use step 1. Prepare before driving (1) General products have been factory hydraulic test and test run, and indicators meet the requirements. (2)Turn on the motor, observe whether the running direction of the motor is correct, it should be clockwise rotation, not reverse. (3) Measure the radial swing and axial string movement of the shaft to see if it meets the requirements, and check whether the seal is sealed tightly at the sealing place. (4) Whether the oil level of the reducer is in normal state, and whether the cooling water of the mechanical seal is kept unobstructed. 2.Normal driving (1)Turn on the circulating cooling water pump, and let the condenser in operation. Then open the concentrate container and vacuum valve. (2) Open the feed valve and pump in the liquid. Turn on the power supply and start the motor, and at the same time, observe whether the rotation direction of the motor is correct. (3)Open the steam valve slowly, connect the traps, make the steam pressure about 0.15MPa. (4) Observe the discharge of the evaporator, wait until the equipment runs stably for 5 minutes, and then sample and analyze the concentration of the concentrate. Concentrate container liquid level will be full, should be switched to another easy, according to the steps for switching. 3. Normal stopping normal stopping order is: close the steam valve - close the feed valve - after the material liquid discharge, close the discharge valve - the flushing of equipment -Stop the motor -Stop the circulating water pump, jet pump -Open the vacuum destroying valve. 4.Safety Precautions (1) In the case of no material liquid or liquid material full, can not start the motor for mixing. (2) The motor is strictly prohibited from running in reverse, and when it is running, you can't touch the rotating parts with your hands. (3) Cannot press the button with wet hands to prevent electric shock. Application of thin film evaporator Thin-film evaporator has the characteristics of high production efficiency, large production capacity, short time of material heating, etc. It can be widely applied to the concentration of dilute solution of various chemical materials. Scraper film evaporator a kind of high-efficiency evaporation, distillation equipment, which is mainly with the help of high rotation will be distributed into a uniform film of liquid and evaporation or distillation. At the same time can also use the scraper film evaporator for deodorization, defoaming reaction and heating, cooling and other unit operations, at present the device has been widely used in Chinese and Western pharmaceutical, food, light industry, petroleum, chemical, environmental protection and other industries, especially the equipment can be used to deal with the concentration of high, viscous, heat-sensitive, easy to scale and other characteristics of the material. Thin film evaporator how to improve efficiency 1. Choose suitable working pressure and temperature: the operating efficiency of the evaporator is related to temperature and pressure, and suitable working pressure and temperature must be chosen to ensure that the efficiency of the evaporator reaches the maximum. 2. Control feed quantity and quality: The control of feed quantity and quality directly affects the operation efficiency of evaporator. Should control the feed flow and quality to improve the operating efficiency of the evaporator. 3. Enhance the cleaning of heat exchanger: the heat exchanger of the evaporator may produce a lot of scale inside because of long-term operation, resulting in the decline of heat transfer efficiency, the heat exchanger should be cleaned regularly to ensure the heat transfer efficiency of the evaporator. In addition to this, the following details can be optimized: 1, reduce the scraper film evaporator steam compressor running speed to make the flow reduced, so that the compressor to avoid the wheezing state, but the steam compressor outlet pressure will also be reduced, can use adjustable blade. 2, check the whole set of evaporator parts connection parts, whether there is leakage appears, timely and regular replacement of the flange connection at the gasket and other seals. 3, the evaporator is regularly cleaned, according to the evaporation system scaling, select the appropriate cleaning cycle, if the evaporation system scaling is serious, try to shorten the cleaning cycle. 4, evaporation system cooling water, water temperature is too high will cause the steam can not be condensed in time, so that the system vacuum is reduced, should be regularly to the circulating pool of cold water, keep the cooling water temperature is basically stable. 5, scraper film evaporator condenser scaling heat transfer efficiency decline, resulting in steam can not be condensed in time, so that the vacuum is reduced, so the condenser should be regularly inspected and cleaned. 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Kettle body 1. Replacement conditions If the reaction kettle has been used for a certain period of time and one of the following situations occurs, it should be replaced: a. The uniform corrosion of the wall thickness of the kettle exceeds the minimum value specified in the design; b. The local corrosion of the wall thickness of the kettle exceeds the minimum value specified in the design, and the corrosion area is greater than 20% of the total area; c. During the hydraulic test, there is obvious deformation or residual deformation of the equipment exceeding the specified value; d. When cracks cannot be repaired due to alkali embrittlement or severe intergranular corrosion in the reactor body or weld seam; e. When the damaged area of the porcelain surface exceeds 15% or the damaged part cannot be repaired; f. Excessive defects (such as serious structural defects that endanger safe operation, unqualified welds, severe incomplete penetration, cracks, etc.) that cannot be repaired. 2. Steel kettle body a. The partial corrosion of the shell is repaired using the arc surfacing method. If the corrosion area is large, the patching method is used for repair. b. Unpenetrating cracks. If the depth of the crack is less than 10% of the wall thickness and not more than 1mm, the crack can be ground flat with a grinding wheel and smoothly transitioned to the metal surface. If the crack depth does not exceed 40% of the wall thickness, the groove can be excavated within the crack depth range, Weld repair should be carried out, but small holes should be drilled at both ends of the crack to prevent it from extending. For long cracks, the step-by-step welding method is adopted (welding from both ends of the crack to the middle) to reduce welding stress and deformation. If the depth of the crack exceeds 40% of the wall thickness, it should be penetrated according to the Narrow crack treatment. c. A narrow crack that penetrates. Before welding repair, drill anti crack holes at both ends of the crack, with a hole diameter slightly larger than the crack width, and process the groove. When the wall thickness is less than 12mm, V-shaped grooves are used; When the wall thickness is greater than 12mm, an x-shaped groove is used. During welding, cracks with a length less than 100mm can be welded in one go; When the crack is long, it is advisable to weld from both ends of the crack to the middle, do not draw an arc, and use multi-layer welding. Except for areas with concentrated stress, welding repairs are allowed for cracks and penetrating narrow cracks in all parts of the kettle body. d. A wide crack that penetrates. Wide cracks should be repaired using the patching method. The length of the excavation should be 50-100mm larger than the length of the crack, and the width should not be less than 250mm. The welded repair plate should be flush with the surface of the body, and the curvature radius should be the same as the body. e. Stainless steel lined drum. When the lining undergoes extensive deformation and the ratio of the bulging height of the lining to the average diameter of the deformation area is less than 0.15, it is advisable to use the water filling and pressure boosting method to restore the deformed lining. For shells or linings with small deformation areas, machines can be used The mechanical top pressing method is used for repair, but attention should be paid to preventing embrittlement during the correction process. 3. Cast iron kettle body For common defects such as sand holes, cracks, pitting corrosion, or local corrosion in cast iron kettle bodies, arc cold welding is usually used for repair. During welding repair, one through hole for crack prevention should be drilled 3-5mm outside the crack endpoint. 4. Glass lined kettle body Glass lining is brittle and prone to damage, and has poor thermal stability. During maintenance, attention should be paid to protecting the porcelain surface. Hanging or tying ropes should be used at designated locations for lifting, and necessary cooling measures must be taken during welding. According to different damage situations, the following repair methods can be used separately. a. Corrosion resistant metal filling method. When micropores are found on the porcelain surface, corrosion-resistant metal materials can be used to make plugs and directly insert them into the micropores. b. When the porcelain surface is slightly damaged, fasten it to the damaged porcelain surface with corrosion-resistant metal bolts and corrosion-resistant material pads. c. Inorganic coating repair method. Clean the surface to be repaired, first remove rust with 15-20% dilute sulfuric acid, then neutralize with a 10% caustic soda solution, then rinse and wipe with water, blow dry with hot air, and finally apply the inorganic coating, slowly heat and cure. Coating weight Quantity ratio, pyroxenite powder: 100, fineness 80-100 mesh; Sodium fluorosilicate: 5, purity>95%; Water glass: 95, specific gravity 1.48. d. Organic coating repair method. The steps are the same as the inorganic coating repair method. Organic coating weight ratio: Epoxy resin: 100 Dibutyl phthalate: 15 M-phenylenediamine: 12-14 Graphite (or other filling materials): 50-100. After coating, heat treatment at a temperature of 80-100 ℃. Slowly raise the temperature during heating, and use it after all have cured. e. The number of fastening clips for the flange of the glass lined kettle body must maintain the specified standard and be evenly distributed. The fastening clip must be tightened symmetrically and evenly along the diagonal direction, without excessive force or one-time tightening. 5. Quality standards for kettle body repair a. The weld seam should have a smooth transition with the base metal. b. The local undercut depth of the weld seam shall not exceed 0.5mm, and the length of the undercut connection shall not exceed 100mm. c. The weld seam should be free of defects such as cracks, incomplete penetration, incomplete fusion, slag inclusion, and porosity. d. The slag and splashes on both sides of the weld seam should be removed thoroughly. e. After repair, there should be no cross welds, and the longitudinal joints between adjacent cylinders and between the head and adjacent cylinder sections should be staggered. The distance between them should be greater than three times the thickness of the cylinder and not less than 100mm. f. The repair of welds should not exceed two times. g. The welding rod material should be selected correctly, and the welding rod and flux must be dried and taken as needed. h. The welded kettle body must undergo a hydraulic strength test. When conducting a hydraulic strength test, the air inside the kettle should be completely discharged. When the wall temperature of the kettle is close to the liquid temperature, slowly increase the pressure, maintain it at the test pressure for 10 to 30 minutes, and then lower it to the maximum working pressure for inspection to ensure there is no leakage or visible abnormal changes It is qualified if there is no abnormal sound during the shape and test process. The kettle body with an external insulation layer or whose external condition cannot be observed shall be maintained at the highest working pressure for at least 2 hours, and it shall be deemed qualified if the pressure does not decrease and there is no abnormal sound. i. The kettle body that requires air tightness testing should be tested after passing the hydraulic test, and the temperature of the gas used in the test should not be lower than 5 ℃. Transmission device V-belt drive a. When installing and aligning the pulley, the parallelism of the axis of the two pulleys shall not exceed 0.01a, and the axial displacement of the width symmetry plane of the two pulleys shall not exceed 0.005a (a is the actual center distance between the two pulleys, unit: mm). b. The fit between the pulley hole and the shaft is H7/k6, and the surface roughness is 1.6/0.8. c. The tension of the V-belt should be uniform and moderate. d. If there are cracks in the pulley hole, or if the groove gap or groove surface is severely worn, it should be replaced. e. The triangular belt is severely worn; Contact with groove bottom; Belt aging; Cracks; Plastic distortion should be replaced. f. The triangular belt on the same wheel should be replaced at the same time. Mixing device a. When the mixing shaft is bent, it can usually be straightened using mechanical pressure method. The straightness of the mixing shaft is 0.10mm/m, and the straightness of the shaft diameter position is 0.04mm/m. b. When the mixing shaft and sealing filler are worn, micro machining and rounding are required. If the wear is greater than 0.5mm, welding should be carried out and machining should be carried out to restore the size of the drawing. The surface roughness is 0.8. c. When the uniform corrosion of the mixer exceeds 30% of the original thickness, it should be replaced. d. Local corrosion, cracks, and deformation of the mixer shall be repaired by welding, shaping, and correction methods. When there is corrosion, detachment, and other damage to the glass lined mixer, repair it according to the enamel repair method. e. The axis of paddle, frame, and anchor mixers should be perpendicular to the blades, with a verticality of 4/1000 of the total length of the blades, and should not exceed 5mm. f. For turbine type agitators with a speed higher than 100r/min, a static balance test should be conducted for the propulsion type agitator. Balance can be achieved by using either the weight removal method or the weighting method. The thickness of the cut or increase should not exceed 1/4 of the wall thickness, and the connection should have a smooth transition. When the speed is less than 500r/min, the unbalanced mass on the outer diameter of the impeller should not exceed 20g. g. The impeller hole and mixing shaft neck of turbine and propulsion mixers are matched with H7/k6, and the surface roughness is selected as 1.6/0.8. h. The rolling bearing is disassembled using special tools, and the oil temperature during hot installation is 140 ℃. It is strictly prohibited to directly heat it with flame. i. When installing the rolling bearing at the lower end of the mixing shaft, the outer ring should not be pressed tightly and there should be an axial thermal expansion displacement of about 0.5-1.0mm left. j. The rolling element and raceway surface of rolling bearings should be free of corrosion, pits, and spots, and the contact should be smooth and free of noise. The journal that fits with the inner hole of the rolling bearing is selected as k6, with a surface roughness of 0.8. The hole that fits with the outer ring of the rolling bearing is selected as K7, with a surface roughness of 1.6. Axial sealing device 1. Packing seal a. The fit between the packing gland and the packing box is H11/d11, and the gap between the gland hole and the shaft is 0.75-1.00mm (shaft diameter 50-110mm). The gap between the mixing shaft and the box is 0.60-1.00mm (shaft diameter 50-110mm). b. The end clearance between the packing gland and the box should be equal, and the error should not exceed 0.3mm. c. The material and specifications of the filler should be used correctly, with a moderate length. The laps of each layer of filler should be evenly spaced and staggered along the circumferential direction, with a 30 ° notch for the laps. The notch should be flat and aligned up and down. d. The filling material must have appropriate compression allowance. e. Ensure that the position of the oil ring is accurate and the oil circuit is unobstructed. 2. Mechanical seal a. The verticality between the shaft and the sealing chamber is generally 0.05mm, the coaxiality with the sealing chamber is generally 0.5mm, the radial runout is 1mm, and the axial displacement is 1mm. b. At the installation of mechanical seals, the surface roughness of the shaft should not be less than 1.6. c. The sealing chamber should be kept clean, and the roughness of the sealing surfaces of the dynamic and static rings should not be less than 0.2, and the water should not leak. d. The adjustment of the end pressure ratio should be appropriate, with good lubrication and minimal leakage. Place the sealing surface in a semi liquid friction state. e. The rotation direction of the spring should be consistent with the working direction of the shaft. f. The perpendicularity of the static ring end face to the axis should not exceed 0.05mm. g. The installed mechanical seal should have a flexible and reliable opening of its moving ring. h. Turn the car by hand, and the sealing area rotates easily without any abnormalities. i. During the airtightness test, it is considered qualified if no continuous small bubbles are generated. Safety accessories Safety valves, rupture discs, and pressure gauges shall be executed in accordance with the relevant regulations of pressure vessels. Liquid level gauge Before installation and use, the liquid level gauge should undergo a water pressure test of 1.5 times the nominal pressure of the liquid level gauge. When one of the following situations occurs, the liquid level gauge should be stopped for maintenance or replacement; a. Exceeding the inspection cycle; b. The glass plate (tube) has cracks or breakage; c. Valve parts are fixed; d. False liquid levels often occur. Other instruments, signal interlocks, safety devices, etc. should comply with relevant regulations. Installation a. The allowable horizontal error for the installation of the kettle body is 1mm/m. b. The allowable error in the installation elevation of the kettle body is ± 5mm, and the allowable error in the position of the warp and weft lines is: ± 5mm when the diameter is less than 1m; ± 8mm for diameters greater than 1m. c. The distance between the pressure tube, thermometer sleeve, heating coil and the mixer shall not be less than 40mm. d. The deviation value between two flanges should be less than 1mm, and the distance between flange faces should be less than 2mm. Only one cushion can be added between the two flanges, and it is not allowed to use additional cushions to eliminate the defect of excessive distance between flange faces. e. The flange sealing surface should be smooth and clean. No mechanical damage, radial scratches, severe rust, welding scars, material residue, and other defects. The cover plate of the manhole and hand hole shall be free from obvious deformation, rust, cracks, and other defects. f. The sealing gasket must be installed upright and coated with a thin layer of scaled graphite paint on both surfaces of the gasket. g. The nut should rotate flexibly on the bolt, but not shake, and the thread should be clean. When tightening the flange, it is required to use a torque wrench to tighten it symmetrically and evenly in two to three times, and the tightening force should not be excessive, insufficient, or uneven. h. It is not allowed to mix bolts of different materials and specifications on the same flange. i. For bolts that require hot or cold tightening during the heating or cooling process, relevant regulations must be followed. Source: Reprint Disclaimer: This article is reproduced online, and the copyright belongs to the original author. If there are copyright issues involved, please contact us and we will delete the content as soon as possible.

Industrial equipment to complete the absorption operation is collectively referred to as the absorption tower. Commonly, there are two kinds of plate tower, packed tower. Plate tower is mostly used for distillation operations, packed tower is mostly used for absorption operations. First, the structure of the packed tower Packed tower is mainly composed of tower, packing and its accessories (defoaming device, liquid distribution device, gas distribution device, packing support device, packing compression device, etc.). 1-foam remover; 2-liquid distributor; 3-packing limiter; 4-shell; 5-packing; 6, 8-unloading packing holes; 7-liquid re Distributor; 9-Packing support plate; 10-Overflow port Packed tower operation, the gas is fed from the bottom of the tower, distributed by the gas distribution device (small-diameter tower is generally not equipped with gas distribution device) distribution, under the action of differential pressure from the bottom upward and the liquid is countercurrent through the packing layer of the gap continuously, while the liquid from the upper part of the tower into the liquid distribution device evenly sprayed through the liquid redistributor. Into the tower, through the liquid distribution device evenly sprayed on the tower cross-section, under the action of gravity along the packing layer downward flow. On the packing surface, the gas and liquid phases are in close contact for mass and heat transfer. Packed tower belongs to continuous contact gas-liquid mass transfer equipment, packing layer gas-liquid two-phase countercurrent contact, packing wetting surface for gas-liquid two-phase contact mass transfer surface, gas-liquid two-phase composition along the tower height of the continuous change, under normal operating conditions, the gas phase is continuous phase, liquid phase is dispersed phase. Under normal operation, the gas phase is continuous and the liquid phase is dispersed. Second, the characteristics of packed tower Compared with the plate tower, packed tower has the following characteristics: 1, large production capacity. Packed tower inner pieces of large openings, large void rate, liquid flood point is high. 2, high separation efficiency. Suitable for dealing with difficult to separate the separation of mixed gases, tower height is lower. 3.Small pressure drop, suitable for decompression operation, and low energy consumption. 4.Smaller liquid holding capacity, suitable for dealing with heat-sensitive materials. 5, less flexible operation, more sensitive to changes in liquid load, if the liquid load is small or large, easy to produce dry tower or liquid flooding phenomenon. 6.It is suitable to deal with easy to foam and corrosive materials, can use filler defoaming and anti-corrosive materials made of filler. 7.It is not suitable to deal with solid or easy to polymerize the material, because the cleaning is more trouble. Third, the role of filler 1, to provide gas-liquid contact area; 2, strengthen the gas turbulence, reduce the gas-phase mass transfer resistance; 3, renew the liquid film surface, reduce the liquid phase mass transfer resistance. Packing is good or bad to determine the performance of the packing tower is the main factor in the operation of the packing characteristics have a greater impact on the surface area, void rate, packing factor and the number of packing per unit of stacked volume. Fourth, the performance of the filler In order to make the packing tower to play a good performance, the filler should meet the following main requirements. 1, to have a large surface area per unit volume of packing layer has a surface area known as the specific surface area of the filler, expressed in δ, the unit is m2/m3. The surface of the filler is only wetted by the liquid phase of the flow, to constitute an effective mass transfer area. Therefore, the packing is also required to have a good surface area. Therefore, the packing is also required to have good wettability and shape conducive to the uniform distribution of liquid. The same kind of filler, the smaller the size, the larger the surface area. 2, the requirement of a high void rate per unit volume of filler has a void volume called filler void rate, expressed in ε, the unit is m3/m3. Generally speaking, the void rate of filler more in the range of 0.45 ~ 0.95, when ε is higher, the gas-liquid through the ability to large When ε is higher, the gas-liquid throughput capacity is large and the airflow resistance is small, and the operation elasticity range is wide. 3, the requirements of packing factor is small δ and ε combined into δ / ε3 form that is the dry packing factor, the unit is m-1. packing factor represents the hydrodynamic properties of the packing. When the packing is sprayed liquid wetting, packing surface covered with a layer of liquid film, δ and ε When the filler is wetted by the spray liquid, the surface of the filler is covered with a liquid film, δ and ε change accordingly, and at this time δ/ε3 is the factor of wet filler, which is expressed as φ. If the value of φ is small, the resistance of filler layer is small, and the gas velocity is increased when liquid flooding occurs, that is to say, it is a good performance of fluid dynamics. 4, the number of fillers per unit stacked volume is appropriate For the same kind of filler, the number of fillers contained in the unit stacked volume is determined by the size of the filler. Packing size decreases, the number of fillers increases, the specific surface area of the packing layer also increases, and the void rate is small, the gas resistance. Gap rate is small, the gas resistance is also a corresponding increase in packing cost. Conversely, if the size is too large, near the tower wall, the packing layer gap is very large, there will be a large number of liquid through this short circuit. In order to control the uneven distribution of gas-liquid phenomenon, the packing size should not be larger than In the tower diameter D 1/10 ~ 1/8. In addition, but also requires packing economic, practical and reliable, requires packing unit volume of light weight, low cost, durable, not easy to block, there is enough institutional strength, for the gas-liquid two-phase media have good chemical stability. Practical application When the actual application, a variety of filler can not have all of the above requirements, need to be based on specific circumstances to choose. 5. Types of packing Types of filler according to the shape of the filler, there are mesh filler and solid filler; According to the material, there are metal filler, plastic filler, ceramic filler and graphite filler; According to the filling method points, there are bulk (chaotic pile) filler and regular filler. Bulk packing is a class of particles with a certain geometric size, stacked in a bulk manner in the tower. According to the different structural characteristics, generally divided into ring-shaped packing, saddle-shaped packing, ring saddle-shaped packing and ball packing. Regular packing is a kind of packing which is discharged neatly and regularly in the tower, and it is divided into grid packing, corrugated packing, pulse packing, etc. according to different geometrical structures. etc. Commonly used in industrial production of packing: Lacy ring, Bauer ring, ladder ring, arc saddle ring, saddle ring, ball, corrugated packing and pulse packing. 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High-pressure hydrogenation reactor is the most important and critical equipment for many chemical industries, and whether its operation is stable and reliable seriously affects the operation of the whole production unit. In order to better use it, it is very necessary to understand the hydrogenation reactor working principle, role and procedures. Hydrogenation reactor working principle Hydrogenation reactor is a kind of pressure vessel, its working principle is to send the raw gas or hydrogen under pressure into a closed container to carry out the chemical reaction, and then discharge the reacted gas through the venting. Since the pressure of hydrogenation reactor is high (generally often more than 10mpa), it is necessary to check and maintain the equipment before use. Hydrogenation plant mainly consists of four parts: heating furnace, heat exchanger, catalyst bed and high pressure storage tank. The heating furnace consists of electric heater, steam heater and thermal oil circulation system; the heat exchanger consists of shell and tube bundle; the catalyst bed is made of stainless steel plate and carbon steel plate welded together; the storage tank consists of liquid-phase tank and gas-phase tank, in which the liquid-phase tank is used to contain the material, while the gas-phase tank is used to collect the discharged gases and sent to the purification and treatment device for further processing. When pressurized operation, first open the power switch of electric heater and the valve of cooling water to preheat the medium temperature in the jacket to reach the set value, then open the feed valve to make the material enter the reaction chamber for heating and warming to a certain temperature, then close the feed valve and open the valve of condensate slowly to prevent the pipeline from clogging due to a sudden drop in temperature or condensation phenomenon that affects the effect of heat transfer; when the needle of the pressure gauge reaches the set value, stop the steam and adjust the pressure down to the required level. When the pressure gauge reaches the set value, stop feeding steam and reduce the pressure to the required working pressure to start normal operation. Role of High Pressure Hydrogenation Reactor The autoclave is generally used for reducing hydrogenolysis. The high pressure reactor has a high reaction rate and reaction degree, which can effectively improve the reaction efficiency and yield. Secondly, the high pressure reactor has a low pollution rate and exhaust emission rate, which is not only favorable to environmental protection, but also can guarantee the quality of products. High pressure reactor can also be convenient and safe to control the reaction parameters and inhibit the occurrence of side reactions, improve the stability and continuity of production. High pressure reactor has low energy consumption and cost, and has a wide range of applications in a variety of chemical reactions, and more and more attention by the industry. Hydrogenation reaction design considerations (1) Hydrogenation reaction plant should be designed in accordance with the requirements of Class A buildings, control room, cabinet room, power substation, laboratory, office and other personnel-intensive areas shall not be arranged in the same building with the hydrogenation reaction. Pressure relief facilities should be set up in the room or part of the hydrogenation reaction with explosion risk; the pressure relief facilities should adopt non-combustible lightweight roof panels, lightweight walls and doors and windows that are easy to relieve pressure. Pressure relief area should be in line with the national standard "Building Design Fire Code". Pressure relief facilities should be set up close to the parts with explosion risk, and should avoid crowded places and major transportation roads. The ground is made of non-sparking flower material to prevent the accident caused by sparks when the iron falls to the ground. Because hydrogen is lighter than air, the upper space of the room for hydrogenation reaction should be well ventilated; the inner surface of the roof should be leveled to avoid dead ends and prevent hydrogen from accumulating. The structural form of roof beam upturned can be used. Combustible gas detection and alarm device should be set above the hydrogenation reactor. When a large amount of hydrogen leakage or accumulation occurs, the gas source should be cut off immediately, ventilation should be carried out, and all operations that may generate sparks should not be carried out. (2) Because most of the hydrogenation reaction adopts palladium-carbon solid catalyst, liquid flooding will be generated during the production process, and the catalyst will block the safety valve orifice throat, resulting in the failure of the safety valve or the inability to return to the seat intact after tripping, it is recommended to connect rupture discs in series in front of the safety valve of the hydrogenation reactor. The discharge pipe should be connected to the accident emergency receiving tank to avoid secondary explosion or pollution; the volume of the accident emergency receiving tank is not less than the volume of the hydrogenation reactor. The vent pipe of the hydrogen-containing tail gas should be equipped with a flame arrestor at the nozzle to prevent backfire and lead to the outdoor, and the nozzle should be 2 m above the ridge. Because of the combustibility of hydrogen and the spontaneous combustion of the catalyst, the hydrogenation reaction system should be purged and replaced before use, and the nitrogen conversion method can be used, and an oxygen content analyzer should be installed on the hydrogenation reactor; its venting system and catalyst activation, regeneration system should be protected by nitrogen seals to avoid contact with the air. (3) The pipes of hydrogen pipeline should be made of seamless steel pipes, and cast iron pipes are prohibited. The connection of pipes should be welded except for the connection with equipment and flange, which can be made by flange connection. Hydrogen piping, valves, couplings, etc. should not be selected and the medium of the chemical reaction of the brass material. It is necessary to strengthen the inspection of the equipment and regularly replace the pipes and equipment to prevent accidents caused by hydrogen embrittlement. Pipeline flanges, valves and other connections should be used to cross the border with metal wires to prevent static electricity buildup. Hydrogen piping shall not pass through buildings unrelated to it. Hydrogenation reaction related electrical equipment explosion-proof level should meet the requirements of "Design Code for Electric Power Installations in Explosive Hazardous Environments", and its explosion-proof level should be CT4. Operation Regulations of High Pressure Hydrogenation Reactor The operation procedure of a complete autoclave reaction is divided into five processes: installation, hydrogenation, sampling, hydrogen release and unloading. (I) Installation 1.Check whether there are flammable and explosive items inside and outside the kettle, and whether there are items unfavorable to air circulation, if so, please remove them. 2.Check whether the valve and kettle are clean, if not, please wash. 3.Close all the valves, except the exhaust valve, start feeding, cover the kettle cover after feeding, pay attention to rotate the nut with even force, make sure the two diagonal screws are tightly screwed to each other, in case of air leakage after tightening. 4.Close the exhaust valve. (B) Check the air tightness of the device Close all the valves, cover the kettle cover, pay attention to rotating the nut should be uniform force, to ensure that the diagonal two screws screw each other to prevent air leakage after tightening. Open the inlet valve to nitrogen to 1MPa, close the inlet valve, observe the pressure change to confirm whether the device leakage. (C) Hydrogenation 1.Check whether the valves are closed tightly. 2.Point the exhaust hose to an open and air-circulating place. 3.On the hydrogen pressure reducing valve, note that the fillet of the hydrogen pressure valve is anti-filament. Nitrogen pressure valve, on the good with soapy water to check whether the leakage, such as leakage, please re-up. 4, in the exhaust port with a vacuum to pump out the air on the liquid surface. 5, open the kettle air inlet valve, open the nitrogen pressure reducing valve nitrogen filling so that the kettle pressure P = 0.2Mpa, close the nitrogen pressure reducing valve, close the air inlet valve, keep about 2 minutes to see whether the pressure gauge pressure drop, in addition to leaning over the side of the head to listen to the valve, kettle cover leakage, such as no leakage, then slowly open the exhaust valve, inside the pressure discharge to 0.01Mpa, close the exhaust valve. 6.Repeat the operation of step 5 once. 7.Open the inlet valve, open the hydrogen pressure reducing valve, fill hydrogen to the required pressure, close the inlet valve, close the hydrogen pressure reducing valve, and then debug other parameters to the required state to make it react. (D) Control sampling 1, every half hour to observe whether the data is normal, such as the pressure decreases, it is necessary to re-supply hydrogen. 2, hydrogen cylinder hydrogen can not be put out, must ensure that there is a certain pressure, P ≈ 0.01Mpa should be abandoned for a new bottle! 3.Take sample. Slowly open the exhaust valve, set the kettle pressure to 0.2Mpa, close the exhaust valve, slowly open the sampling valve to the reaction liquid bubbling, close the sampling valve to take a sample, and then clean the sampling port, can not let the flammable residue. (E) Drain hydrogen Confirm the end of the reaction, slowly discharge hydrogen to the end, pay attention to a little pressure within the exhaust valve, so as to avoid the entry of oxygen, open the inlet valve, flush nitrogen to 0.2Mpa to close the inlet valve, and then slowly open the exhaust valve, release the mixed gas inside, will be the end of the time to re-enter the nitrogen, so that the exchange of gas for three times, the gas on the liquid surface with a vacuum pump to pump out the exhaust valve, open the exhaust valve, the sampling valve, and begin to discharge the material from the bottom valve. Note that because of the oxygen easily spontaneous combustion of substances such as Pa/c, RaneyNi, so do not spill outside the container, such as spillage, please immediately use a wet towel dipped out into a bucket of water, and then a small amount of dilute acid to destroy it, immediately close the bottom valve after discharging. (F) Unloading After discharging the kettle, it should be cleaned immediately, and the following steps should be carried out before cleaning: 1, the reaction solvent from the exhaust valve into the kettle, clean off most of the residue, inject water half kettle stirring for 10 minutes. At this time, you can open the kettle cover to clean the inner wall of kettle. 2.When cleaning, the kettle cover and sampling valve must be cleaned, and the kettle should be slightly filled with nitrogen when there is water in the kettle. 3, temporarily unused reactor, it is best to add 70 volumes of clean anhydrous ethanol soaking kettle, you can not tighten the screws. Original link: https://www.xianjichina.com/news/details_304477.html Source: xianjie.com Disclaimer: This article is a network reproduced, the copyright belongs to the original author. If it involves copyright issues, please contact us, we will remove the content at the first time.

21 What are the specific requirements for tower side piping design? (1) tower side piping generally have reflux, feed, side line extraction, steam extraction steam, reboiler inlet and return piping, etc., in order to make the valve closed without accumulation of liquid, the valves on the above piping should be directly connected directly with the tower body orifices, inlet (outlet) feeding pipe Inlet (outlet) material piping at the same angle there are more than two inlet (outlet) material openings, the pipeline should consider a certain degree of flexibility; (2) fractional distillation tower side line to the steam tower pipeline, such as regulating valves should be installed close to the steam tower. To ensure that the regulation of the same with a section of liquid in front of the residence. The height of the liquid column should meet the requirements of the process. 22 tower bottom piping design features? (1) the bottom of the tower operating temperature is generally high, so in the arrangement of the bottom of the tower pipeline, its flexibility should meet the requirements of the relevant standards or codes. In particular, the bottom of the tower pumping pipeline and the pump is connected, the pipe should be short and less bends, and need to have enough flexibility to reduce the pump nozzle force. Less pump nozzle force. Tower bottom pumping line should be led to the tower skirt or outside the base, tower skirt is strictly prohibited to set the flange into the instrument fittings and other fittings. The bottom of the tower to the bottom of the pump pumping pipe in the horizontal pipe section shall not have a "bag shape", should be "step by step low", so as to avoid the bottom of the tower pump to produce cavitation phenomenon, the bottom of the pump. The isolation valve on the pumping pipe should be as close as possible to the tower, and easy to operate. (2) Unless it is an auxiliary reboiler, or two or more parallel reboilers operating at the same time, and the requirements of a wider range of regulation of its heat load, the bottom of the tower to the reboiler pipeline is generally not suitable for the installation of valves. Tower bottom kettle type reboiler with a centrifugal pump, the elevation of the reboiler should meet the centrifugal pump required by the effective corrosion allowance, while making the tower bottom liquid level and the reboiler liquid level of the difference in the formation of the static head of pressure is sufficient to overcome the pressure of the descending liquid pipe, reboiler and ascending tube pressure Losses. Therefore, the piping arrangement should meet the flexibility requirements at the same time, the piping should be short, the elbow should be less. 23 What requirements should be met for the arrangement of manholes on the tower? (1) The manhole of the tower should be located in the operating area of the tower, where it is more convenient, safe and reasonable to enter and exit the tower, and should be located in the same orientation. (2) Set up the manhole must pay attention to the internal components of the tower, generally should be located in the tower plate above the bubble area, shall not be located in the tower of the liquid drop tube or liquid tank area; (3) Manhole (or hand hole) on the tower, generally every 3-8 layers of tower plate layout; (4) The height of the manhole center from the platform surface is generally between 600mm and 1000mm, the most suitable height of 750mm; (5) A tower on the manhole should be arranged in the same vertical line, so that it is neat and beautiful. 24 tower orifice orientation requirements? (1) tower orifice orientation should meet the working principle of the tower parts and structural requirements, the design should pay attention to the overall structure of the equipment components and the relative orientation of the orifice; tower top gas-phase openings are arranged in the middle of the tower top header; tower reflux openings, generally arranged in the tower plate Piping side of the upper; gas-phase feed openings in the tower above the plate, parallel to the liquid-reducing pipe; gas-liquid mixed-phase feed openings in the tower above the plate, and set up a distribution pipe; vapor steam openings in the lower part of the vapor tower plate, and add a gas distribution pipe. Side line product extraction outlet in the liquid drop tube below the common arc range, it is appropriate to set up the extraction bucket, for the middle liquid drop tube of the double overflow tower plate, the extraction outlet can be arranged in the place at any angle, set up the extraction bucket; the bottom of the tower extraction outlet is located in the middle of the tower bottom header cover, and set up to prevent the Vortex plate, the pumping outlet should be extended to the skirt of the tower outside. (2) For the tower with tower plate, the manhole should be arranged in the tower diameter parallel to the overflow weir of the tower plate, or not parallel when conditions do not allow, but the net distance between the manhole and the overflow weir in the horizontal direction should be not more than 50mm. (3) The orientation of the manhole lifting, and the setting of the ladder should be uniformly arranged, and in case of accident, the direction of smooth closing of the man cover and the direction of evacuation of people should be the same. (4) The level meter interface can be directly connected to the level meter through the root valve or connected to the level meter connecting pipe through the root valve. The level meter interface shall not be arranged within a 60° angle opposite the inlet, unless the inlet is protected by an internal baffle. External float level control tubes connected directly to the tower shall be baffled. Liquid level meter, level control float, alarm and other devices are often located in the tower platform or localized platform end, in order to facilitate maintenance. (5) The manometer interface should be arranged in the gas phase area of the tower, so that the manometer reading is not affected by the liquid level pressure head. (6) Sampling port and temperature measurement port arrangement, gas phase sampling port and temperature measurement port should avoid the gas phase area of the tower plate drop tank, liquid phase sampling port and temperature measurement port should be located in the drop tube area of the tower plate within the liquid holding layer; for easy crystallization of the liquid phase sampling tube should be to the tower plate. (7) Positioning of the column at the top of the tower should be such that it can reach the top of the lifting point outside the platform when rotating, as well as the position of all the holes in the platform. 25 What orientation should an equipment orifice orientation diagram indicate in addition to the orifice? In addition to indicating the process and utility media pipe openings, it should also indicate: (1) the orientation of the instrumentation receiver, including temperature, pressure, liquid level; (2) Manhole, hand hole and the orientation of the column, the orientation of the skirt exhaust hole; (3) The orientation of the equipment ground bolt holes or the orientation of the support lugs; (4) The location of lugs, ground plates and nameplates; (5) The orientation of the internal ladder, the bottom of the skirt to strengthen the support. 26 How to determine the fixed side of the horizontal container support? Identify the most important (difficult or demanding) one pipe for flexibility calculation from the pipes to be connected to this vessel, such as the pipe with large compensation volume and pipe diameter, as the basis for deciding the type of support. The position of the fixed side support should be favorable to the pipe Flexibility calculation. 27 What are the requirements for orifice orientation of horizontal vessels? (1) Liquid inlets and outlets on the equipment shell should be spaced as far apart as possible. The liquid inlet pipe should be located as far away from the vessel level gauge connection as possible; (2) The liquid level meter interface should be arranged in the position where the operator can easily observe and conveniently maintain the misery. Sometimes in order to reduce the receiver port on the equipment, in situ liquid level meter, liquid level controller, liquid level alarm and other measuring devices can be installed on the joint box. Wave level meter pipe Position, should be arranged with the level control valve group on the same side; (3) The manhole cover connected by hinge (or lifting post) should not affect other pipe openings or pipelines when opened; (4) The safety valve receiver port should be located at the top of the vessel. 28 What are the general requirements for piping arrangement of horizontal vessels? The piping of the container (tank) is relatively simple; the piping arrangement of the vertical container is generally similar to the piping arrangement of the tower, and also takes the design along the wall of the tank, and the valves on the piping are also required to be directly connected to the opening; this can avoid the accumulation of liquid. Horizontal container equipment arrangement, generally the long direction of the tank and the corridor is perpendicular so its piping, such as gas outlet piping, safety valve outlet piping, liquid outlet piping, etc., are oriented towards the corridor, and the corridor on the relevant; connected to the main pipe. The elevation of the piping connected to the opening at the top of the vessel should be higher than that of the main pipe connected to the corridor so that it can be connected to the top of the main pipe. When the liquid outlet pipe at the bottom of the container is connected to the pump under the pipe, the elevation of the bottom of the pipe should not affect the passage of people. (1) For piping connecting the liquid outlet of the horizontal container with the suction port of the pump, the minimum headroom is 2200mrn if the piping is overhead on the passage; (2) For piping connected to the bottom orifice of the horizontal container, the minimum headroom of the liquid discharge outlet from the floor at its low point is 150mm; (3) safety valve outlet discharge into the closed piping system, should avoid the accumulation of liquid, and to meet the safety valve outlet piping along the medium flow direction into 45 ° down to the top of the closed pipe connected to the main, and no "pocket". If the safety valve is installed away from the vessel, check the pressure from the vessel to the safety valve inlet pipe. vessel to the safety valve inlet piping pressure drop; (4) The regulating valve group of the pipeline on the top of the storage tank is arranged on the platform; (5) The platform should be set up according to the inert condition of equipment and piping arrangement. 29 heating furnace piping layout design of the general requirements? (1) heating furnace piping arrangement with the heating furnace type is different, in the heating furnace piping arrangement, should be inlet and outlet piping, fuel system piping, soot blowing gas piping, fire extinguishing steam piping and other unified consideration; (2) for the cylinder furnace inlet and outlet pipe, usually ring-shaped arrangement around the furnace body, can be supported on the ground or the furnace body. The ring-shaped main pipe should be arranged above the watchman's door so as to facilitate the normal operation and maintenance of the watchman's door; (3) If necessary, in the furnace outlet pipe elbow. Tee or reducer larger than the other, or from the top of the furnace vertically down to the bottom of the position, the installation of anti-vibration mounts; (4) If rupture discs are provided in the piping, they must not be oriented toward the operation or equipment; (5) The main regulating valve group is usually arranged between the pipe gallery and the furnace body and pay attention to the access requirements; (6) Valves on steam, fuel oil, or fuel gas piping should be arranged on vertical piping near the watchdog door and meet the requirements for regulation and maintenance; (7) In cold areas, steam tracing shall be used for fuel oil piping in accordance with regulations; (8) The pipeline near the nozzle should adopt the connecting structure which is easy to dismantle for cleaning and maintenance; (9) Platforms and ladders shall be provided at frequently operated valves and observation areas at higher locations; (10) The discharge point of the fuel pipeline should be at least 15m above the furnace and should be discharged into the collection system, not directly into the sewer; (11) Pipes connected to the furnace, as far as possible, centrally arranged for support, to achieve coordination. The purpose of aesthetics; (12) For the feeding pipeline of the heating furnace, the flow rate of each road should be kept uniform; for the all-liquid-phase feeding pipeline, generally each road is equipped with a flow control valve to regulate the flow rate of each road, or else the pipeline should be symmetrically arranged, and the inlet and outlet pipelines of the gas and liquid phases must be used in a symmetrical Arrangement to ensure that the pressure drop in each way is the same; (13) annular oil line should be the highest temperature calculation of thermal compensation, and the use of pipeline natural compensation to absorb its thermal expansion. 30 What are the general requirements for the fuel gas piping arrangement of the heating furnace? (1) Fuel gas should be set up to distribute the main pipe, so that the fuel gas of each nozzle can be evenly distributed; the fuel gas branch pipe is led out from the upper part of the distribution main pipe, so as to ensure that the fuel gas into the nozzle does not carry water or condensed oil. At the end of the fuel gas distribution head is equipped with a DN20 drain valve, which is convenient for the test run flushing and shutdown sweeping line after the liquid discharge, as well as the start of sampling to analyze the oxygen content in the pipeline, the liquid discharge pipe should be equipped with two liquid discharge valves to avoid leakage, the valve can be on the ground or on the platform. The valve can be operated on the ground or platform. Fuel gas shut-off valve should be located 15m away from the heating furnace. (2) in the fuel gas pipeline to set the flame arrestor, you can prevent the flame spread, flame arrestor according to the principle of action can be divided into dry flame arrestor and safety water seal two kinds. Industrial production facilities in the heating furnace on the fuel gas pipe generally use multi-layer copper wire mesh dry flame arrestor. Flame arrestor. The flame arrestor should be placed close to the nozzle. Pipe flame arrestor and burner distance should not be greater than 12 m. In this way, the flame arrestor will not be in a serious burst zha conditions, life can be extended. 31 shell and casing type heat transfer equipment piping arrangement should be considered? (1) process piping arrangement should pay attention to the cold, hot logistics flow direction, the general cold flow from bottom to top, hot flow from top to bottom; (2) The piping arrangement should be convenient for operation, and does not hinder the maintenance of the equipment; (3) The elevation of the foundation of the heat transfer equipment should meet the lower drain pipe from the ground or platform surface is not less than 150mm; (4) heat transfer equipment pipeline, there can only be a high point and a low point, to avoid the middle of the "gas bag" or "liquid bag", and set up a high point of emptying, low point of the net; in the heat transfer equipment should be avoided as far as possible within the region of pipeline crossings and bypasses; try to minimize the pipeline The number of layers of overhead piping, generally 2-3 layers; (5) two or more than two parallel heat transfer equipment inlet pipe straight symmetrical arrangement, the gas-liquid two-phase flow heat transfer equipment must be symmetrically arranged in order to achieve good heat transfer; (6) heat transfer equipment, measuring instruments on the import and export piping, should be installed near the operating channel and easy to observe and overhaul; (7) and the heat transfer equipment connected to the easy to condense medium of the pipeline or pipeline containing solid particles of the sub-line, the shut-off valve should be located in the horizontal pipeline, and should prevent the formation of dead-end accumulation of liquid; (8) in cold areas, outdoor heat exchanger equipment on the upper and upper water piping should be provided with a drain valve and anti-freeze connecting pipe. 32 arranged in groups of heat transfer equipment and its piping arrangement should be designed? (1) group arrangement of heat transfer equipment in the area, can be laid on the ground or platform piping, but should not interfere with access and operation; (2) When there is no regulating valve or drain pipe on the pipeline, the clearance from the bottom of the pipe to the ground should be greater than or equal to 150mm; (3) The regulating valve group should be arranged parallel to the cold exchange equipment. (4) The net distance of piping arrangement between heat exchanging equipments arranged in groups should be greater than or equal to 650mm; (5) Piping arrangement should be considered for each heat exchanger equipment pipe box and header cover disassembly space; (6) The import and export piping of heat exchanger equipment connected in parallel should be arranged symmetrically. 33 vertical reboiler piping arrangement requirements? (1) The piping must be flexible enough to compensate for the thermal expansion of the equipment and piping under various operating conditions; (2) When the heavy boiler pipe port and the tower of the pipe port butt, if the load conditions allow, it is best to set up a tower support heavy boiler bracket, and the location and form of the bracket should be able to meet the tower and pipeline expansion of the displacement and loading requirements; (3) When piping, the space required for dismantling the heavy boiling pipe bundle in situ should be left; (4) For single-pass fixed-tube plate heat exchanger with expansion joints on the shell, the influence of such expansion joints should be considered when piping, flexibility analysis and support design of equipment are carried out; (5) When the length to diameter ratio (L/D) of the reboiler is greater than 6.0, it is desirable to have guided supports; (6) When the valves and blinds of the reboiler are assessed to be more than 3m above the ground, a platform should be provided on the tower. 34 shell and tube horizontal horizontal reboiler piping arrangement requirements? (1) in the thermal expansion of the permissible stress range, heavy boiler drop liquid pipe and steam pipe, should try to resist short and straight, reduce the number of elbows to reduce the pressure drop; (2) when the heavy boiler has two steam rising mouth, in order to make its tube flow green equal, steam rising province should be symmetrically arranged. If the rising steam pipe diameter and arrangement of different asymmetric, should try to make the resistance of the two pipe sections are equal. Otherwise, the flow rate of the rising steam pipe with large resistance is small. Will make the heat distribution is not uniform; (3) from the reboiler pumped out of the liquid for the saturated liquid, if the piping system produces a pressure drop, the liquid will begin to flash, resulting in gas-liquid two-phase fluid flow, affecting the operation and accuracy of the control and measurement instruments. Therefore, when arranging the saturated liquid pipeline The basic principle is to minimize the pressure drop, and in the measurement or control instrumentation does not appear before the vertical rise of the pipe section; (4) reboiler piping heating medium inlet piping is usually equipped with temperature control valve and its valve group, these valves are generally arranged near the reboiler piping inlet ground or platform surface. 35 What are the specific requirements for piping design of air coolers? (1) Fractionator top to the air cooler oil and gas piping, generally should not appear "liquid pockets". When the air cooler import and export no valve or two-phase flow, the pipeline must be symmetrically arranged, so that the flow of each piece of air cooler uniform; (2) The inlet pipe of the air cooler should be connected close to the nozzle of the air cooler; if necessary due to stress or installation, the outlet pipe may not be connected close to the nozzle, and the cross-sectional area of the pipe should be larger than the sum of the cross-sectional areas of the branch pipes; (3) When the population of the air cooler is gas-liquid two-phase flow, each branch pipe should be inserted into the population collection pipe from below; in order to make the fluid distribution at the bottom of the collection pipe uniform; at the same time, a shutdown discharge pipe is set below the collection pipe and connected to the outlet pipe of the air cooler; (4) The population pipe of the air cooler is high; if the distance is long, it is necessary to set up a special pipe rack in the middle to support the pipe; (5) The softened water return system of wet air cooler is self-flowing pipeline, therefore, attention should be paid to the arrangement of the pipeline system and the bends should not be too many. The return water main pipe should have a slope in the direction of media flow; (6) air cooler operating platform with semi-fixed steam blowing joints, the valve should be located in easy access, and should pay attention to the direction of the steam joints to ensure safe operation. 36 pump piping design general requirements? (l) pump inlet and outlet piping should be set up to cut off the network, the pipeline must be flexible enough to reduce the piping role in the pump pipe mouth of the stress and moment; (2) pump suction piping should meet the pump's "cavitation margin" requirements, the pipeline should be as short as possible, fewer bends should not have air pockets. If it is difficult to avoid, should be set at the high point of the bleeder valve; (3) When the pump suction pipe is long, it is appropriate to design a certain slope (i = 5 ‰); pump than the container is appropriate to slope to the pump, the pump is appropriate to slope to the container than the container is appropriate to slope to the container; (4) In the pump population immediately downstream of the pipeline shut-off valve, there should be a filter or temporary filter, in order to prevent the pump fluid backflow caused by the pump impeller reversal, the pump outlet should be equipped with a check valve; (5) Under the premise of meeting the process requirements, the pump piping. Valve handwheel shall not affect the normal operation of the pump and the space required for maintenance and inspection; (6) Reciprocating pump inlet and outlet piping design should take into account the impact of fluid pulsation. 37 What are the types of pump protection lines? What is its role? There are six kinds of pump protection lines, the role of which is to make the pump body is not damaged and normal operation, according to the conditions of use to set the pump protection line. (1) Warm pump line - in the transport medium temperature greater than 200 ℃ high temperature oil, there is a backup pump should be set DN20 ~ 25 warm pump line; (2) small flow line - when the working flow of the pump is less than 30% of the rated flow of the pump, the pump should be set up in the lowest flow rate of normal operation of the small flow line; (3) balance line - for the delivery of room temperature saturated vapor pressure higher than the atmospheric pressure of the liquid or in the bubble point state of the liquid, in order to prevent the liquid into the pump to produce steam or bubbles into the pump should be added to balance the line caused by cavitation; (4) Bypass line - used for pump test run or non-normal operation of the state of the outlet valve is closed, can still make the pump in operation. Generally in the valve before and after the very high pressure difference between the occasions set with a limited flow orifice pole bypass valve; (5) Anti-coagulation line - conveying at room temperature solidification of the high pour point or high solidification point of the liquid, its standby pumps and pipelines should be set up anti-coagulation line, so as to avoid clogging of the standby pumps and pipelines; (6) safety valve line - for electric reciprocating pumps, gear pumps and screw pumps and other displacement pumps, the outlet side of the safety valve line, when the outlet pressure exceeds the fixed pressure value, the safety valve jumps, the fluid returns to the pump population tube. 38 centrifugal compressor piping arrangement of the general requirements? (1) Centrifugal compressor shell has two forms: vertical split type for high-pressure, there shall be no pipelines and other obstacles in front of the machine; horizontal split type for medium and low pressure, there shall be no pipelines and other obstacles on the upper part of the machine; (2) The arrangement of the import and export pipelines should minimize the number of elbows to reduce the pressure drop under the conditions of thermal compensation and allowable stress; (3) The inlet and outlet pipe nozzles are generally facing downward, supported by the center of the machine shell, and their thermal expansion should be absorbed by the pipes during operation; (4) plant set up in the compressor nozzle for the upper inlet and outlet, in its inlet and outlet nozzle pipeline shall be set up removable short section, so that the compressor overhaul. 39 reciprocating compressor piping design of the general points? (1) compressor import and export piping arrangement should be short and straight, minimize the number of elbows, but the export pipeline has thermal expansion, the pipeline should be flexible; (2) The pipeline arrangement should consider the self-flow of liquid to the liquid separation tank, when the pipeline appears "liquid bag", there should be a low point of discharge; (3) multiple units side-by-side arrangement, its inlet and outlet pipeline valves and instruments should be arranged in an easy to operate, easily accessible place; (4) In order to prevent the compressor import and export pipeline vibration, the necessary vibration analysis should be carried out. Piping arrangement should be as low as possible, the bracket is laid on the ground, and for the independent foundation, increase the rigidity of the bracket and pipeline; (5) compressor medium for combustible gases, pipeline low-point Ran condensation, high-point venting valves should be set up silk plug, pipe cap or flange cover to prevent leakage, and the unit around the pipe trench should be filled with sand to avoid the accumulation of combustible gases; (6) the arrangement of compressor import and export pipeline, should not affect the maintenance crane walking; (7) The compressor pipeline should be arranged under the operating platform, so that there is a more spacious operation and maintenance space around the unit. Source: Reprint Disclaimer: This article is reprinted from the Internet, the copyright belongs to the original author. If copyright issues are involved, please contact us, we will remove the content at the first time.

01 What are the types of tower arrangement? Specific requirements for? (1) single-row arrangement, generally more single-row arrangement, when there are two or more towers or vertical containers on one side of the pipeline corridor, the general centerline alignment, such as two or more towers set up a joint platform, it is appropriate to centerline alignment or tangent alignment; (2) multi-row arrangement, for the smaller diameter body higher tower, can be arranged in double rows or into a triangle arrangement, so that the platform can be used to link the tower together to improve its stability. However, the platform rooted members should be used to guide nodes that can slide to adapt to the thermal expansion effects of different operating temperatures; (3) frame type arrangement, for the diameter DN ≤ 1000mm tower can also be arranged in the frame or the side of the frame. The frame is used to improve its stability and set up platforms and ladders. For the segmented tower arranged on the frame, when it is not possible to use motorized lifting gear, it should be set up on the frame for maintenance and lifting facilities. 02 What are the requirements for the arrangement of the tower and its associated equipment? The tower and its associated equipment such as feed heater, non-flame heated reboiler, condensation cooler at the top of the tower, reflux tanks, pumping pumps at the bottom of the tower, etc., it is desirable to be arranged close to the order of the process, and if necessary, can be formed into an independent operating system located in a zone, so as to facilitate the operation and management. 03 along the pipeline corridor arrangement of the tower and vertical pipe apparatus and how to determine the spacing of the pipeline corridor? (1) When arranging the pumps between the tower and the pipe corridor, it should be determined according to the operation, maintenance and piping requirements of the pumps; (2) When the pump is not arranged between the tower and the pipe corridor, the distance between the outer wall of the tower and the centerline of the pipe rack column should not be less than 3m. 04 How to determine the distance between tower and tower or between tower and other adjacent equipment? Tower and tower or tower and other adjacent equipment between the distance, in addition to pipelines, platforms, meters and small equipment and other layout and installation requirements, should also meet the operation, maintenance access and foundation layout needs to play. The net distance between two towers should not be less than 2.5m. 05 tower and vertical container installation height should meet what requirements? (1) when the use of internal pressure or fluid gravity will be sent to other equipment or pipeline materials, should be sent to the equipment or pipeline by its internal pressure and the pressure and height of the determination; (2) When pumping with a pump, should be by the pump's cavitation margin and the pressure drop in the suction pipe to determine the installation height of the equipment; (3) The installation height of the tower with a non-open-flame heated reboiler shall be determined by the interrelationship between the tower and the reboiler required by the process and the operational requirements; (4) The minimum headroom required for piping installation and operation at the bottom of the tower should be met, and the base surface of the tower should not be less than 200mm above the ground. 06 What are the general requirements for the arrangement of heat exchange equipment? (1) Shell and tube heat exchanger equipment associated with the fractionating tower, such as reboiler at the bottom of the tower, condensing cooler at the top of the tower. It is desirable to connect the process sequence is arranged in the vicinity of the fractionating tower; (2) two materials for heat exchange heat exchanger, it is appropriate to arrange in the two materials import and export pipeline connected to the nearest position; (3) a material and several different materials for heat exchange shell and tube heat exchanger, should be arranged in groups; (4) water or refrigerant cooling several groups of different materials cooler, should be arranged in groups; (5) arranged in groups of heat exchanging equipment, it is appropriate to take the center line of the base of the support alignment, when the spacing of the support is not the same, it is appropriate to take the center line of the base of the base of one end of the support alignment. In order to facilitate the connection of pipelines, the ground arrangement of heat exchangers can also be used to import and export pipeline nozzle Center line alignment; (6) heat exchanger equipment should be arranged on the ground as far as possible, but a larger number of heat exchanger equipment can be arranged on the frame: (1) Floating head type heat exchanger should meet the following requirements when arranged on the ground: Floating head and tube box on both sides should have a width of not less than 0.6m of open space, floating head in front of the end of the appropriate width of not less than 1.2m of open space; Tube box in front of the tube box from the end of the tube box should be left than the length of the tube bundle at least 1.5m long open space. 2) Floating head type heat exchanger in the frame arrangement, should meet the following requirements: Floating head end of the platform in front of the headroom should not be less than 0.8m;. The headroom of the platform in front of the pipe box end should not be less than 1mn, the platform adopts removable railings, and the space required for the tube bundle extraction area should be considered; The height of the frame should be able to meet the heat exchanger tube box and floating head of the head cover lifting needs. (7) in order to save space or process operation can be two heat exchanger equipment overlap in the arrangement. But for two-phase flow media or shell diameter greater than or equal to 1.2m heat exchanger should not overlap the arrangement; (8) between heat exchangers, heat exchangers and other equipment between the net distance should not be less than 0.7m; (9) Heavy oil or polluting materials heat exchanger equipment should not be arranged on the frame; (10) operating temperature higher than the spontaneous combustion point of the material above the heat exchanger, such as no floor or platform separation, should not be arranged for other equipment. 07 What are the general requirements for the arrangement of reboiler? (1) The spacing between reboilers and towers heated by open flame should be arranged according to the spacing requirements of heating furnace and tower in the fire code; (2) Horizontal reboiler heated with steam or hot carrier should be arranged close to the tower, and maintain a certain height difference with the tower (determined by the process design), the distance between the two should meet the requirements of piping arrangement, the reboiler pumping bundle should be one end of the maintenance site and access; (3) Vertical reboiler is appropriate to use the tower as a support arranged on the side of the tower, and maintain a certain height difference with the tower (determined by the process design). There should be enough space above it for maintenance; (4) a tower needs more than one parallel vertical reboiler, reboiler location and installation height, in addition to ensuring that the process requirements, but also to meet the requirements of the import and export of the set of pipe layout and easy to operate and maintenance. 08 What are the general requirements for the arrangement of air cooler? (1) The air cooler (hereinafter referred to as air cooler) should be arranged on the downwind side of the device in the direction of the wind with the minimum frequency throughout the year; (2) The air cooler should be arranged above the main pipe gallery, on the top floor of the frame or on the top of the tower; (3) The air cooler should not be arranged in the operating temperature equal to or higher than the spontaneous combustion point of the material and the top of the equipment for conveying and storing liquefied hydrocarbons; otherwise, it should be protected by the isolation of non-combustible material partitions; (4) When multiple air coolers are arranged together, they should be arranged in the same form and should be arranged in columns; a part of column arrangement and another part of row arrangement should be avoided; (5) The pitched-roof air cooler should not face the ventilation to the dominant wind direction in summer. The pitched-roof air-cooler should be arranged in rows; if it is arranged in rows, there should be a space of not less than 3m in the middle of the two rows; (6) The distance between the frame columns of two humidifying air coolers or dry and wet combined air coolers arranged side by side should not be less than 3m; (7) A platform should be set up at the tube box and transmission machinery at both ends of the tube bundle of the air cooler; (8) There should be a necessary maintenance site and passageway on the ground on the side of the frame or main pipe gallery where the air cooler is arranged. 09 How can the arrangement of air-cooler avoid the hot air circulation among themselves or each other? (1) Arrange air coolers of the same type at the same height; (2) Neighboring air coolers are arranged close to each other; (3) Dry blower-type air-cooler and induced draft air-cooler are arranged separately in groups, and the induced draft air-cooler should be arranged on the downwind side of the wind direction of the minimum annual frequency of the blower-type air-cooler; (4) When the induced draft air cooler and the blast air cooler are arranged together, the blast air cooler tube bundle shall be raised. 10 heating furnace arrangement of the general requirements? (1) The open-flame heating furnace should be centrally located at the edge of the device near the fire escape, and should be located at the downwind side of the annual minimum frequency wind direction of the combustible gases, liquefied hydrocarbons, and Class A-B liquid equipment; (2) The heating furnace and other open flame equipment should be arranged together; (3) Several heating furnaces can be arranged in rows aligned with the centerline of the furnace. The net distance between two heating furnaces should not be less than 3m; (4) when the use of motorized maintenance equipment lifting heating furnace tube, there should be motorized maintenance equipment access and maintenance site. For the heating furnace with a horizontal furnace tube, in the extraction of the side of the furnace tube, the length of the maintenance site should not be less than the length of the furnace tube plus 2m; (5) The distance between the outer wall of the heating furnace and the edge of the maintenance road should not be less than 3m; (6) For the heating furnace with steam generator, the steam bag should be located on the top of the heating furnace or adjacent to the frame; (7) heating furnace and its subsidiary fuel gas separation tank, fuel gas heater spacing, should not be less than 6m; (8) when the heating furnace has air preheater, blower, induced draft fan and other auxiliary equipment, auxiliary equipment should be arranged so as not to interfere with its own and the heating furnace maintenance; (9) heating furnace and open arrangement of liquefied hydrocarbon equipment between the fire distance should not be less than 22.5m, when the equipment set up between the non-combustible material of the solid wall, the distance can be reduced, but shall not be less than 15m. the height of the solid wall should not be less than 3m, from the heating furnace should not be greater than 5m, and should be able to prevent combustible gases from escaping into the body of the furnace; (10) when the liquefied hydrocarbon equipment plant or class A gas compressor room towards the heating furnace side of the closed wall, the heating furnace and plant spacing can be reduced, but shall not be less than 15m. 11 vertical container arrangement of the way what are the requirements? Vertical container shape and tower is similar, only the internal structure is not as complex as the internal structure of the tower, vertical container arrangement and installation height, etc. can refer to the tower layout requirements, in addition, the following requirements should be considered: (1) In order to operate conveniently, the vertical container can be installed on the ground, floor or platform, or it can cross the floor or platform, and support on the floor or platform with lugs; (2) When the vertical container is installed across the floor or platform, the liquid level indication and control instruments on the container shall be avoided as far as possible to cross the floor or platform as well; (3) When the vertical vessel is equipped with a large load stirrer inside in order to prevent the solidification of viscous materials or the settlement of solid materials, the supporting structure should be set up from the ground as far as possible in order to avoid the influence of vibration; (4) for the top opening of the vertical container, the need for manual refilling, the height of the refilling point should not be higher than the floor or platform 1m, such as higher than lm, should be considered to set up a refilling platform or steps. 12 horizontal container layout and installation height requirements? (l) horizontal container should be arranged in groups. Horizontal container should be arranged in groups and aligned according to the centerline of the base of the support or aligned according to the tangent line of the head. The clearance between horizontal containers can be considered as 0.7m. (2) in the process design to determine the size of the horizontal container, as far as possible to choose the same length of different diameters of the container, in order to facilitate the arrangement of equipment. (3) determine the installation height of the horizontal container, in addition to meeting the requirements of the material gravity flow or pump suction height, but also to meet the following requirements: Container under the liquid collection package, there should be a liquid collection package for the operation and detection of instrumentation required by the sufficient space; Containers need to be set up under the operating channel, the bottom of the container piping and ground clearance should not be less than 2.2m; Horizontal containers of different diameters are arranged in groups on the ground or on the same floor or platform, the elevation of the center line of horizontal containers of smaller diameters can be raised appropriately so that the elevation of the cylinder surface of horizontal containers with larger diameters is the same so as to facilitate the setting of joint platforms. (4) When the horizontal container is arranged in the pit, the accumulation of water and toxic, flammable and explosive medium in the pit shall be properly dealt with. The size of the pit should meet the operation and maintenance requirements of the container. Rainy areas can be considered in the upper part of the pit to set up a canopy. (5) Horizontal container platform should be set up to consider the operation of manhole and liquid level meter. The top platform elevation should be 150mm lower than the top nozzle flange. When the liquid level meter upper interface height from the ground or operating platform more than 3m, the liquid level meter should be installed in the straight ladder. Nearby. For the centralized arrangement of the horizontal container can be set up joint platform. 13 What kinds of pump layout? There are three types of pump arrangement: open-air arrangement, semi-open-air arrangement and indoor arrangement: (1) Open-air arrangement of the pumps in the open air, usually concentrated in the pipeline corridor below the side of the confusion, can also be scattered in the vicinity of the pumping equipment. The advantage is good ventilation, easy operation and maintenance; (2) Semi-open-air arrangement of semi-open-air arrangement of the pump is suitable for rainy areas, generally in the pipeline corridor below the arrangement of the pump, above the upper part of the pipeline with a canopy. Or the pump is arranged in the frame of the lower ground, to frame platform as a canopy. These pumps can be arranged according to the pump design requirements, the pump is arranged into a single row, double row or multiple rows; (3) indoor arrangement in cold or sandy areas can be arranged indoors the pump. If the process requires that the equipment is arranged indoors, the pumps belonging to it should also be arranged indoors. 14 What are the specific requirements of the pump layout? (1) rows of pumps should be arranged in accordance with the fire requirements, operating conditions and material characteristics of the group layout; pumps open-air, semi-open-air arrangement; operating temperature equal to or higher than the auto-ignition point of combustible liquids pumps should be centrally located; and the operating temperature is lower than the auto-ignition point of combustible liquids pumps should be not less than 4.5m between the fire spacing; and the liquid hydrocarbon pumps should be not less than 7.5m between the fire spacing; (2) When the pumps are arranged in rows, it is desirable that the pump ends out. Population center line alignment, or the pump end of the foundation edge line alignment; (3) When the pumps are arranged in double rows, it is desirable to place the power ends of the pumps in two rows opposite to each other and leave the maintenance channel in the middle; (4) When the pump is arranged below or outside the main pipe gallery, the minimum clear width of the channel in the pump area is 2m, and the minimum clear height is 3m, and the width of the operation channel in front of the pump end, should not be less than 1m; (5) When the pump is arranged below or outside the main corridor, regardless of single or double rows, the centerline of the pump and driver should be perpendicular to the direction of the corridor; (6) When the pump is arranged indoors, the net distance between two rows of pumps should not be less than 2 m. The net distance between the pump end or the pump side and the wall should meet the requirements of operation and maintenance, and should not be less than l m. The centerline of pump and driving machine should be perpendicular to the direction of the corridor; (7) In addition to the installation of small pumps on the joint foundation, the net distance between the two pumps should not be less than 0.7m; (8) pump foundation surface should be 200mm above the ground, the minimum shall not be less than 100mm; in the pump suction port before the installation of the filter, the pump foundation height should be considered filter to facilitate cleaning and disassembly; (9) Vertical pumps arranged in the main corridor below or below the frame, the upper part of the pump body should leave the space required for installation and maintenance; (10) conveying extremely hazardous substances (such as propylene?). Hydrocyanic acid, etc.) of the pump room and other pump room should be set up separately; (11) The fire pump room should be equipped with dual power sources; (12) public standby pumps should be arranged in the middle of the corresponding pump; (13) The pump layout should take into account the pipeline flexibility design requirements. 15 compressor arrangement of the general requirements? (1) compressor and its ancillary equipment should be arranged to meet the requirements of the manufacturer; (2) The compressor should be arranged near the equipment to be pumped, and its ancillary equipment should be arranged close to the unit; (3) The arrangement of combustible gas compressors should meet the following requirements: The distance between the compressor and the open flame equipment and non-explosion-proof electrical equipment should be in accordance with the current national standard "Code for Design of Electric Power Installations in Explosive and Fire Hazardous Environments" (GB 50028) and "Code for Design and Fire Protection of Petrochemical Enterprises" (GB 50160); It is desirable to have open-air arrangement or semi-open arrangement. In cold or sandy areas can be arranged in the plant; Single drive power equal to or greater than 150kw of gas compressor plant, and other A, B, C rooms should not be shared with a building; compressor above, shall not be arranged for A, B, C liquid equipment, but the self-use of the high lubricating oil tanks are not subject to this limit. (4) single-floor layout of the compressor, when the foundation is high, it is appropriate to set up the operating platform as needed; when more ancillary equipment, it is appropriate to two-floor layout. 16 What requirements should the installation height of the compressor meet? The installation height of the compressor should be determined according to its structural characteristics. The installation height of the compressor whose inlet and outlet are at the bottom should comply with the following requirements: (1) Clearance requirements between the inlet and outlet connecting pipes and the ground ; (2) Requirements for the height of the connection between the inlet and outlet connecting pipelines and the pipelines on the pipe gallery; (3) Requirements for the installation height and size of the filter on the suction pipe; (4) In order to reduce vibration should reduce the installation height of reciprocating compressors. 17 device control room, power distribution room, laboratory layout should comply with what fire regulations? (1) Control room, power distribution room should be located in the ground floor of the building, if the production needs or by other conditions, the control room, power distribution room can be arranged in the second or higher level; (2) In installations where heavier-than-air combustible gases may be emitted, the indoor floors of the control room, power distribution room and laboratory shall be at least 0.6m higher than the outdoor floor; (3) The external wall of the control room facing the side of the equipment with fire hazard shall be a solid wall of non-combustible material without doors, windows or openings; (4) No on-line analyzing primary instruments of combustible gases, liquefied hydrocarbons and combustible liquids shall be installed in the room of control room or laboratory. When the above instruments are installed in the adjacent rooms of the control room and laboratory, the intermediate partition wall shall be a firewall. 18 What requirements should be met for the channel setting of the production device? What is the minimum width and minimum clear height of the channel in the device? When arranging the device, comprehensive consideration should be given to setting up necessary passages and sites according to the needs of construction, maintenance, operation and fire fighting. Inside the device, roads should be used to separate the device into equipment and building areas covering an area of not more than 10000m2. When the esterification polymerization of synthetic fiber device, extraction and post-processing plant covers an area of more than 10000m2, should be set up on both sides of the channel. The main vehicular access in the device should be connected with the factory road. (1) The installation of the device fire escape should meet the following requirements: When the device width is greater than 60m, should be set up in the device through the fire escape; Device width is less than or equal to 60m, and the device outside the two sides of the fire escape, may not be set up through the fire escape. Device not through the road should be equipped with a return site. The width of the road should not be less than 4m, the road shoulder pipe racks and road edge clearance should not be less than lm, the road inside the line of the turning radius should not be less than 7m, the clear height of the road should not be less than 4.5m. (2) maintenance channel should meet the motorized maintenance equipment on the width of the road, turning radius and bear the load requirements, and can lead to the lifting hole of the equipment maintenance. (3) The main vehicular access, fire fighting access and maintenance access should be set up together. (4) operation channel, should be based on the production operation, inspection, small maintenance, such as the frequency and the distribution of the operation point to decide. 19 along the tower piping arrangement design should be considered? (1) Should meet the requirements of process piping and instrumentation flow chart; (2) The piping arrangement should be planned from the top of the tower to the bottom of the tower from top to bottom, and the location of the top piping and large-diameter piping and the direction of the self-flowing piping should be considered first, then the pressure piping and general piping should be arranged, and the bottom piping and small-diameter piping should be considered last; (3) Convenient operation, maintenance and safe and reliable, economically reasonable should be considered; (4) Each pipeline should be as short as possible according to its starting and ending points, but must meet the requirements of pipeline flexibility; (5) Each pipe should be arranged along the tower as much as possible, and pay attention to have a "good appearance": There are two cases can be considered: First, each pipe is arranged separately; Second, according to the pipeline arranged in groups (this way plus the centralized load of the pipeline is large, should obtain the consent of the equipment designers); On the pipeline side along the outer wall of the tower is a concentric circle arrangement, or along the outer wall of the tower is a tangent arrangement. 20 What are the main points of tower top piping design? (1) Tower top piping generally has tower top oil and gas, venting and safety valve outlet piping. Tower top venting pipeline is generally installed at the top of the tower top oil and gas pipeline at the highest level of the top of the pipe section, and should meet the requirements of the fire code; (2) tower top oil and gas pipeline medium is generally gas-phase, pipe diameter is large, the pipe as short as possible, to be "step by step low", should not appear bag-shaped pipe, and has a certain degree of flexibility; (3) Each pipe along the tower, the need to set up a load-bearing bracket in the upper part, and set up a guide bracket in the appropriate location, so as to avoid excessive force on the nozzle; (4) The oil and gas pipeline at the top of the fractionation tower is generally not insulated, only anti-scald; such as the pipeline to more than one cold exchange equipment, in order to avoid bias flow, should be arranged symmetrically; (5) The top of the tower for two-stage condensation, the piping should be arranged so that the condensate level by level of self-flow, oil and gas piping and condensing road inlet branch should be symmetrically arranged, so that the flow rate is uniform; (6) when the tower top pressure control with thermal bypass, the thermal set of pipes should be insulated, as far as possible the shortest, and its regulating valve should be installed in the reflux tank "on the upper part of the pipeline shall not appear" bag "to avoid the accumulation of liquid; (7) Decompression tower top oil and gas pipeline and tower openings directly welded without flange connection to reduce leakage. 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Heat exchanger can be broadly divided into shell and tube heat exchanger and plate heat exchanger and so on according to the structure. Among them, the shell and tube type has a long history, is the most widely used type of heat exchanger, has the advantages of easy manufacturing, low production cost, wide range of materials, easy to clean, adaptable, large capacity, reliable, adaptable to high temperature and high pressure. I. Fixed tube and plate heat exchanger Fixed tube and plate heat exchanger tube plate at both ends, the use of welding methods and shell connection fixed Advantages: 1. simple and compact structure, in the same shell diameter, the largest number of rows of tubes, the minimum bypass. 2. each heat exchanger tube can be replaced, and easy to clean the tube. 3. Compared with other shell and tube heat exchangers, the tube plate is the thinnest, low cost. Disadvantages. 1. Shell process cannot be mechanically cleaned; 2. when the temperature difference between the heat exchanger tube and the shell is large (greater than 50 ℃) when the temperature stress, the need to set up expansion joints in the shell, and thus the shell pressure by the expansion joints can not be too high strength limitations. Fixed tube and plate heat exchanger for the shell side of the fluid is clean and not easy to scale, the temperature difference between the two fluids is not large or large temperature difference but the shell pressure is not high occasions. Because of such heat exchangers have concentrated the advantages of shell and tube heat exchanger, so it is widely used. II. Floating head type heat exchanger Floating head type heat exchanger for fixed tube and plate heat exchanger defects in the structure of the improvement, the two ends of the tube plate only one end of the tube plate and shell fixed, while the other end of the tube plate can move freely in the shell, the end is called floating head. Advantages: 1. the shell and tube bundle is free of thermal expansion, so when the temperature difference between the two media is large, the temperature difference between the tube bundle and the shell does not produce stress. 2. Floating head end is designed as a detachable structure, so that the tube bundle can be easily inserted or withdrawn (also designed as non-detachable), so as to provide a convenient maintenance, cleaning. Disadvantages: 1. the small cap on the floating head end can not know the leakage situation during operation, so special attention should be paid to its sealing during installation. 2. Complex structure, bulky, the cost is about 20% higher than the fixed tube plate type, material consumption. 3. the gap between the tube bundle and the shell is large, so the harmful E flow path is more serious, in the design should try to avoid this short circuit. 4. The pressure in the shell stroke is limited by the sealing of the sliding contact surfaces. Floating head type heat exchanger is suitable for the temperature difference between the shell and tube wall is large, or easy to corrode and easy to scale the occasion. III. U-tube heat exchanger U-tube heat exchanger has only one tube plate, the tube is bent into a U-shape, and the two ends of the tube are fixed on the same tube plate. Advantages: 1. Because the shell and tube are separated, the tube bundle can be freely expanded and contracted, and will not produce thermal stress due to the temperature difference between the tube wall and shell wall, and has good thermal compensation performance; 2. the tube course is a double-tube course, the process is longer, the flow rate is higher, the heat transfer performance is good, and the pressure capacity is strong; 3. U-tube heat exchanger has only one tube plate, and no floating head, so the structure is simple, the cost is cheaper than other heat exchangers; 4. The tube bundle can be withdrawn from the shell, and the outside of the tube is easy to clean. Disadvantages: 1. it is difficult to clean inside the tube, so the fluid inside the tube must be clean and not easy to scale the material; 2. due to the structure of the heat transfer tube type relationship, the replacement of the tube in addition to the outer tube, most of the internal tube can not be replaced; 3. there is a gap in the center part of the tube bundle, so the fluid is easy to go short-circuit, affecting the heat transfer effect, so there is usually a dummy tube or intermediate baffle to reduce the flow of this dead zone; 4. The tube plate arranged on the tube is less, the structure is not compact; 5. the curvature of the U-tube part of the curvature is different, the length of the tube is not the same, so the distribution of materials is not as uniform as the fixed tube-plate heat exchanger; 6. After the tube is blocked due to leakage, it will cause the loss of heat transfer area; U-tube heat exchanger, generally used in the case of high temperature and high pressure. Especially when used in the case of high pressure, the wall thickness in the bend section should be thicker to make up for the thinning of the tube wall after the bend. Ⅳ. Stuffing box heat exchanger Stuffing box type heat exchanger tube plate also has only one end fixed with the shell, the other end of the packing box seal. Advantages: 1. has the advantages of floating head type heat exchanger, but also to overcome the shortcomings of the fixed heat exchanger, the structure is simpler than the floating head, easy to manufacture, easy to repair and clean. 2; 2. tube bundle can also be free to expand, so do not need to consider due to the tube wall, shell wall temperature difference caused by thermal stress, and the tube and shell process can be cleaned, processing and manufacturing than the floating head is convenient, and less expensive. Disadvantages: 1. packing seal is easy to leak, so the shell process pressure can not be too high, generally less than 4.0MPa; 2. not easy to use in the shell process for volatile, flammable, explosive and toxic media occasions. Packing box type heat exchanger for the tube, shell wall temperature difference or medium easy to scale, need to be cleaned often and the pressure is not high occasions. For some serious corrosion, temperature difference and often have to replace the tube cooler, the use of packing box type heat exchanger than floating head or fixed heat exchanger is much superior. Currently used packing box type heat exchanger are smaller, used in the diameter of 700mm or less, large diameter packing box type heat exchanger used very little, especially in the operation of the pressure and temperature under the conditions of the higher less. Source: Reprint Disclaimer: This article is a network reproduced, the copyright belongs to the original author. 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A distillation column is a tower-type vapor-liquid contact device for distillation. As the main equipment of the distillation process, there are two main types of plate columns and packed columns. According to the operation mode can be divided into continuous distillation column and batch distillation column. Today we will take you to understand the structure and principle of plate column. Plate column Plate towers are usually composed of a cylindrical shell and a number of plates (or plates) set horizontally along the tower height at a certain spacing. Plate tower plate The plates of a plate tower can be divided into two categories: those with drop tubes and those without drop tubes. In general, the liquid with a drop tube is staggered flow, and the liquid without a drop tube is counterflow. Plate tower can be divided into bubble tower, floating valve tower, sieve plate tower, tongue and slant plate and so on. Among them, the bubble tower, floating valve tower and sieve plate tower are the most widely used in industrial production. 1 Blister tower Blister tower plate is the earliest industrial application of the tower plate, it is composed of gas pipe and bubble. Blister is installed on the top of the ascending tube, divided into two kinds of round and strip, the former is more widely used. There are three sizes of blister, f80, f100 and f150mm, which can be selected according to the size of the tower. The lower periphery of the bubblers has a lot of teeth slits, which are generally triangular, rectangular or trapezoidal. Blisters are arranged in triangular shape on the tower plate. The edge of the blister is equipped with longitudinal tooth slits, and the center is equipped with a gas lift tube. The rising gas pipe is directly connected to the tower plate. The gas phase under the tower plate enters into the rising tube, and then blows out from the teeth to contact with the liquid phase on the tower plate for mass transfer. Due to the rising tube, the liquid leakage phenomenon under low gas velocity is avoided. Advantages: the tower plate operation flexibility, tower efficiency is also higher, more widely used. Disadvantages: the structure is complex, the tower pressure is reduced, low production intensity, high cost. 2 sieve plate tower Sieve plate tower plate referred to as the sieve plate, its structure is characterized by a number of uniform holes in the tower plate, aperture is generally 3 ~ 8mm. sieve holes in the tower plate for the positive triangular arrangement. Overflow weir is set on the tower plate, so that the plate can maintain a certain thickness of the liquid layer. The advantages of the sieve plate tower are simple structure, low cost, large production capacity, small drop of liquid surface on the plate, the gas pressure is reduced, while the tower plate efficiency is higher. The disadvantage is that the operating flexibility is small, the sieve holes are easy to clog, and it is not suitable to deal with easy coking, viscous materials. 3 Floating valve tower Float valve is the 20th century after World War II began to study the 50s began to enable a new type of tower plate, and then gradually appeared in a variety of types of float valve Its type has a round, square, strip and umbrella, etc.. More use of circular float valve, and circular float valve is divided into a variety of types. Characterized by the float valve canceled the bubble tower bubble and rising gas pipe, instead of openings in the tower, the valve installed on the limit of the three legs. However, the valve piece is easy to fall off or jammed during operation. Float valve can float freely with the change of gas speed up and down, which improves the operating flexibility of the tower plate, reduces the pressure drop of the tower plate, and has high efficiency of the tower plate, which is widely used in the production. Plate tower overflow device The overflow device of plate tower refers to the overflow weir (outlet weir) and the descending liquid pipe. The liquid is discharged to the bottom of the tower by gravity from the top plate by plate, and forms a flowing liquid layer on the plate surface of each layer of the tower plate; the gas is pushed by the pressure difference, and is discharged from the top of the tower through the openings evenly distributed on the tower plate and spread to each layer of the tower plate in turn. Tower plate on the gas-liquid two-phase contact state is to determine the two-phase flow on the plate hydrodynamics and mass and heat transfer law of the important factors. When the liquid flow rate is certain, with the increase of gas velocity, the following contact states can occur: 1 bubble contact state When the gas velocity is low, the gas passes through the liquid layer in the form of a bubble. Due to the small number of bubbles, the formation of gas-liquid mixture is basically liquid-based, gas-liquid two-phase contact surface area is not large, the mass transfer efficiency is very low 2 honeycomb contact state With the increase in gas velocity, the number of bubbles is increasing. When the bubble formation rate is greater than the bubble floating rate when the bubble accumulation in the liquid layer. Bubbles collide with each other to form a variety of polyhedral bubbles. As the bubble is not easy to rupture, the surface is not renewed, so this state is not conducive to heat and mass transfer. 3 foam contact state When the gas velocity continues to increase, the number of bubbles increased dramatically, bubbles continue to collision and rupture, most of the liquid on the plate at this time in the form of liquid film exists between the bubbles, the formation of a number of small diameter, perturbation is very intense dynamic foam, due to the foam contact state has a large surface area, and constantly updated, is a better contact state. 4 jet contact state When the gas velocity continues to increase, the liquid on the plate upward sprayed into droplets of varying sizes, the larger diameter droplets fall back to the tower plate by gravity, the smaller diameter droplets are taken away by the gas, the formation of liquid foam entrainment. The droplets return to the tower plate and are dispersed, this droplet formation and aggregation repeatedly, so that the mass transfer area increases, the surface is constantly updated, is a better contact state. Industrial production generally want to present foam state and spray state two states. Because the gas velocity of the spray contact state is higher than the foam contact state, so the spray contact state has a larger production capacity, but the spray state liquid foam entrainment is more, if not well controlled, it will destroy the mass transfer process, so most of the tower are controlled in the foam contact state work. Source: reproduced Disclaimer: This article is a network reproduced, the copyright belongs to the original author. If it involves copyright issues, please contact us, we will remove the content of the first time.

Chemical separation technology is an important branch of chemical engineering, whether it is petroleum refining, plastics chemical fiber, hydrometallurgy, isotope separation, or the refining of biological products, the preparation of nano-materials, desulfurization of flue gas and fertilizer pesticide production, and so on can not be separated from the chemical separation technology. Chemical production of raw materials and products in the vast majority of mixtures, the need to use the system of differences in the physical properties of the components or with the help of the separator to make the mixture to be separated and purified. It is often a key step to obtain qualified products, fully utilize resources and control environmental pollution. Along with the rapid development of the chemical industry, separation technology has also gained high speed development. On the one hand, the research and application of traditional separation technology has been progressing continuously, the separation efficiency has been improved, the processing capacity has been increased, the engineering enlargement problem has been solved gradually, and new separation devices have been appearing continuously; on the other hand, in order to adapt to the technological progress and put forward new separation requirements, the development, research and application of membrane separation technology, supercritical extraction technology, adsorption technology and other existing separation technologies have become the frontiers of the separation engineering research. The topic. The importance of chemical separation process Chemical separation process is the operation of separating a mixture into two (or several) products of different compositions. A standard chemical production plant consists of a reactor and a number of separators for the purification of raw materials, intermediates and products. Firstly, the separation process supplies the chemical reaction with raw materials of the right quality, removes hazardous substances and improves yields; secondly, the reactants are separated and purified to obtain the right products and to recycle unreacted products; furthermore, it plays an invaluable role in the full utilization of resources and in the protection of the environment. In addition, the separation process in the full utilization of resources and protection of the environment to play an indispensable role, so the separation process in the chemical industry production occupies a very obvious position. Classification and Characteristics of Separation Process Separation processes commonly used in chemical production can be divided into two categories: mechanical separation and mass transfer separation. The separation object of mechanical separation process is a mixture composed of more than two phases. The purpose is simply to separate the phases, as long as a simple mechanical method can be separated from the two phases, and there is no material transfer phenomenon between the two phases; for example, filtration, sedimentation, centrifugal separation, cyclone separation and electrostatic precipitation and so on. The mass transfer separation process for the separation of various homogeneous mixtures, which is characterized by the phenomenon of mass transfer occurs, according to the different physicochemical principles based on the mass transfer separation process commonly used in industry is divided into equilibrium separation process and the rate of separation process, that is, the process of separation of energy and matter. 1. Equilibrium separation process The process is to make the homogeneous mixture system into a two-phase system with the help of a separation medium, and then the components of the mixture in the phase equilibrium of the two phases in different distribution based on the realization of the separation. Examples are: evaporation, distillation, absorption, adsorption, extraction, leaching, drying, crystallization, ion exchange, etc. For example, in the process of traditional extraction, its energy is transferred to the extractant without rules, and then the extractant diffuses into the substrate material, and finally the substrate is dissolved or entrapped with a variety of components diffuse out. Microwave extraction is a new technology to improve the efficiency of microwave energy extraction, due to the existence of substances with different dielectric constants, the degree of absorption in the microwave energy will be different, so the heat generated and the heat transferred to the surrounding environment are also different. In the microwave field, the size of the absorption capacity of the substrate material part of the region to be selectively heated, from which the extracted material through the substrate to separate, and then into the microwave absorption capacity is relatively weak, the dielectric constant is relatively small extractant. Microwave extraction process: Microwave extraction process is roughly as follows: raw material pretreatment (cleaning, crushing or slicing) → material mixing and solvent → microwave extraction → filtration → concentration → separation → extraction of components Balanced separation process has experienced a long period of application practice, with the progress of science and technology and the rise of high-tech industries, increasingly perfect and constantly developing, evolved a variety of new separation technology with characteristics. In the traditional separation process, distillation is still listed as the first petroleum and chemical separation process, so strengthen the method in the continuous research and development. 2. Rate separation process Rate separation process is in some kind of driving force (concentration difference, pressure difference, temperature difference, potential difference, etc.) under the action, sometimes in the selective permeability of the membrane with the use of the components of the diffusion rate of the difference between the components to achieve the separation of components. The raw materials and products handled by this type of process usually belong to the same phase, with only compositional differences. The principle of membrane separation technology is a unit operation that utilizes the difference in permeation rates of each component in the fluid to the membrane to achieve separation of components. The membrane can be solid or liquid, the fluid being processed can be liquid or gas, and the driving force for the process can be a pressure difference, concentration difference, or potential difference. Microfiltration, ultrafiltration, reverse osmosis, dialysis and electrodialysis are the more mature membrane separation technologies with large-scale industrial applications and markets. Among them, the common point of the first four is used to separate the liquid containing dissolved solute or suspension material, solvent or small molecule solute through the membrane, solute or macromolecule solute is retained by the membrane, the different membrane process of solute particles of different sizes of retention. Electrodialysis is the use of charged membrane, driven by the electric field force, from the aqueous solution or electrolyte enrichment. Gas separation and osmotic evaporation are two membrane technologies that are being developed and applied. Gas separation is more mature, with industrial-scale applications such as separation of oxygen and nitrogen in air, separation of hydrogen from ammonia plant mixtures, and separation of carbon dioxide from methane in natural gas. Osmotic evaporation is a membrane separation process with phase change, which utilizes the difference in dissolution and diffusion properties of different components of the mixed liquid in the membrane to achieve separation. Because it can be used to remove trace water in organic matter, trace organic matter in water, as well as to realize the separation between organic matter, the application is promising. Emulsion membrane is a branch of liquid membrane separation technology, which is a membrane separation operation with liquid membrane as the separation medium and concentration difference as the driving force. Liquid membrane separation involves three phases of liquid, the raw material phase containing the separated components, the product phase receiving the separated components, and the membrane phase between the above two phases. Liquid membrane separation is mainly used in hydrocarbon separation, wastewater treatment, and extraction and recovery of metal ions. Mass transfer separation process of distillation, absorption, extraction and some other unit operations with a long history has been widely used, membrane separation and field separation and other new separation technologies in product separation, energy saving and environmental protection has shown their superiority. Types of separation methods and principles of selection 1. Types of separation methods There are many different types of material separation methods, that is because there are a variety of chemical production materials, and in the process of selecting the separation method, often in accordance with the separation of various components of the material is separated in accordance with the different chemical and physical properties to determine the choice; in accordance with the chemical and physical properties to distinguish between, there are the following five types of common separation methods: ① solid mixtures of separation methods, ② gas-solid-phase mixtures of separation methods, ③ liquid mixtures of separation methods, ③ liquid mixtures of separation methods, separation methods, separation methods, separation methods, separation methods, separation methods, separation methods, separation methods ③ liquid mixture separation method, ④ liquid-solid phase mixture separation method, ⑤ gas mixture separation method. 2. Principle of separation method selection In the selection of separation methods, the degree of refinement of the product and the production value of the product to be considered, for a high degree of refinement and high production value of the product, do not need to consider the cost of separation, you can choose some of the high efficiency separation methods, for some relatively low production value and a large number of products, you need to consider the cost of separation, you can choose those separation steps less or relatively simple separation methods. Try to avoid the presence of solid-containing logistics in the production process, should be as far as possible in advance to remove the solids in the logistics, due to their relatively large energy consumption in the transportation, and the liquid or gas-containing logistics is quite easy to form pipeline blockage. In the separation of materials mixed with many different substances, the separation order should be considered as follows: in order to avoid the process being affected, should try to separate the substances that are easy to lead to extremely harmful and side reactions, and at the same time, the substances that need to be separated under high pressure should also be considered to be separated first; in addition, the first to be separated out of the easiest to separate the components, and left to the last to be separated is the most difficult to separate the components. Selection of separation methods or the main principles of economic rationality and technical reliability to consider. For example, distillation and extraction are both methods of separating liquid mixtures, according to the degree of technological maturity, distillation lies above the extraction, if you can take the distillation of separated materials, should avoid using extraction, if the boiling point of the mixture of large deviations, the use of distillation can be simple to carry out the separation, there is no need to use distillation, so that the operating costs and selection of investment are relatively low. The selection of separation method must be targeted, because it is a technical work, only to be separated from the chemical and physical properties of the material, as well as the separation requirements are clearly grasp the best choice. Wide range of chemical applications, the needs of the environment are illustrated in the chemical separation process in the national economy and people's livelihood in the status and role, and demonstrates the broad prospects for the separation process, modern society can not be separated from the separation technology, the separation of technology development in the modern society. Source: Reprint Disclaimer: This article is reprinted on the Internet, the copyright belongs to the original author. If it involves copyright issues, please contact us, we will remove the content at the first time.

First, the principle and role of reboiler Reboiler is a heat exchanger that can reboil the fluid in the heat exchange process. Its main principle is to flow in the heat exchanger through the pipeline inside the low-pressure steam or other liquids, in the process of heating to produce a one-time boiling, and then in the process of continuing to heat the process of reboiling, thereby improving the efficiency of heat transfer. Reboiler is mainly used in chemical, petroleum, food, pharmaceutical and other industries, in the steam generator, air conditioning systems, distillation equipment and other fields play an important role. Among them, it is most widely used in the evaporator, which can greatly improve the heat exchange efficiency and also save energy consumption. In addition, the reboiler can also be used to heat low-quality fluids, such as oil, water, sewage and chemicals. Second, the advantages and disadvantages of reboiler Compared with other types of heat exchangers, reboiler has the following advantages: 1. energy efficient: reboiler can be released in the heat transfer process to make full use of latent heat, improve the efficiency of heat transfer, but also to save energy consumption. 2. High-speed heat transfer: In the process of heat transfer in the reboiler, due to the one-time boiling and reboiling, so the heat will be transferred quickly, so that high-speed heat transfer can be carried out. 3. Wide range of applications: reboilers are widely used in many industries, such as chemical, petroleum, pharmaceuticals and so on. However, the reboiler also has certain disadvantages: 1. easy to produce oscillation: due to the presence of a large number of bubbles in the reboiler fluid, so in the process of heat transfer is prone to oscillation, thus causing some damage to the equipment. 2. susceptible to scaling and corrosion: in the process of using the reboiler, due to the presence of high temperature and high pressure fluid, so it is susceptible to scaling and corrosion, thus affecting the heat transfer efficiency. Third, the types of reboiler Reboiler according to its internal structure, can be divided into the following categories: 1. shell and tube type reboiler: shell and tube type reboiler is the heating medium flow in the tube, while the cooled medium flows in the shell of the heat exchanger. Its structure is simple, easy to make, but also to meet the needs of large flow. 2. straight tube type reboiler: straight tube type reboiler is the heated medium and the heating medium flow in two separate pipelines, so as to achieve the process of heat transfer. Compared with shell and tube reboiler, its structure is more compact, but also can achieve higher heat transfer efficiency. Fourth, the reboiler repair and maintenance In the process of using the reboiler, it is necessary to carry out regular repair and maintenance to ensure its normal operation. Specifically include the following aspects: 1. Regular cleaning: regular cleaning of the reboiler internal, you can avoid scaling and corrosion, so as to ensure the efficiency of heat transfer. 2. Regular inspection: Regularly inspect the internal and external structure of the reboiler to ensure that it is in good operating condition and avoid equipment damage. 3. Installation of safety valves: In the process of using the reboiler, it is necessary to install safety valves to ensure that the equipment in the event of abnormalities can be automatically discharged pressure to ensure the safety of the operator. Through the introduction of this article, we understand that the reboiler is a highly efficient heat exchanger, which can be widely used in the chemical industry, petroleum, food, medicine and other fields. At the same time, through regular repair and maintenance, can ensure the normal operation of the reboiler, to ensure the safety and reliability of the equipment. Source: Reprint Disclaimer: This article is reproduced on the Internet, the copyright belongs to the original author. If it involves copyright issues, please contact us, we will remove the content at the first time.

When designing steam piping in a chemical plant, in order to ensure the quality and efficiency of the design, the pipe diameter should also be reasonably selected, and the piping should be arranged to meet the requirements of the stress, in addition to paying attention to a number of other details to avoid the phenomenon of water hammer. 01 Design of steam piping Many different pipelines are set up in the chemical plant, generally arranged outside the plant or along the plant, supported in the air with a bracket, becoming a pipe corridor. There are specific requirements for the configuration of the pipe corridor, generally the process material pipes are arranged in the first layer and the first layer of the corridor, the utility piping is arranged in the third layer, and the instrumentation cable trough plate is arranged in the fourth layer. Among them, the steam pipes are arranged in the third layer. In order to facilitate the setting of π-shaped compensator, generally the steam pipeline should be arranged on the side of the corridor. At high temperatures, the steam pipes will expand, and the π-compensator can be used to absorb the thermal expansion of the pipes. Because bellows expansion joints are more expensive and do not have a long service life, they are generally not used to absorb the thermal expansion of steam pipes. When determining the installation position of the compensator, the pipeline should first be analysed strictly so that the compensator can be set centrally. The pipelines with high temperature and large compensation capacity are usually set up on the outside, while the pipelines with low temperature and small compensation capacity are set up on the inside. pi-shaped compensators are usually set up in the middle, and guiding frames are set up on both sides of the compensators to determine the distance between the guiding frames and the compensators according to the stress of the pipelines. When calculating the thrust of the bracket and the stress of the steam piping, the stress of the entire steam piping is calculated. Generally, there are multi-layer pipe galleries in chemical plants, and steam pipes are installed in the upper layer of multi-layer pipe galleries, so that cryogenic pipes and liquid hydrocarbon pipes are not adjacent to each other. On the same layer, steam piping and electronic instrumentation cables can be arranged simultaneously, but to ensure that the interval between the two is not less than 200 mm, or steam piping can be arranged in the electronic instrumentation cables in the lower layer, but the interval is not less than 500 mm. 02 Steam piping liquid discharge facilities design In general, the special liquid discharge is set in the steam pipe in the warming stage. In the driving time because it will produce a large amount of condensate, so it is also necessary to set up special liquid discharge facilities. The setting of the drain facility is selected according to the steam pressure level. UHP piping does not produce condensate under normal conditions, and there is no condensate piping of the corresponding specifications on UHP steam piping, so there are generally no hydrophobic facilities installed on UHP piping. UHP piping is characterised by thick walls, difficult openings, and high pressures, so generally there are no liquid separation packages installed either. Under normal circumstances, condensate is not normally generated in high-, medium- and low-pressure piping. However, in order to prevent a large amount of condensate from being generated in steam piping during the warm-up or start-up phases, it is necessary to install trapping facilities such as drain valves and liquid separation packages on these steam piping. When installing steam piping, a manifold should be installed at the end of the steam main, and the interval between manifolds on the steam main is also subject to certain regulations: if in a saturated state, the interval between manifolds inside the unit is 80 mkm; if in a state of overheating, the interval between manifolds should be 160 mkm; if in a state of downhill, the interval between manifolds outside the unit should be 300 mkm; if in a state of downhill, the interval between manifolds outside the unit should be 300 mkm; if in a state of overheating, the interval between manifolds should be 160 mkm. In the case of a downhill condition, the interval between the manifolds outside the unit should be 300 mkm, and in the case of a downhill condition, the interval between the manifolds outside the unit should be 200 mkm. The steam separator is normally installed near the boundary of the side of the unit when the saturated steam main enters the unit. In addition, the lower part of the distributor should be equipped with a measure for frequent dewatering. If a superheated steam main enters the unit, there is no need to install a water separator. A drain hole should be provided at the lower end of the steam vent pipe for the steam vent pipe to be discharged directly to the atmosphere, and a DN 15 pipe should be connected to the drain, funnel, etc., wherever appropriate. Guiding and load-bearing brackets should also be set up on the steam vent pipe. Because the flooded steam pipe is often discharged or connected to discharge, it should be led to the main operating area or to a place where there are not too many operators. 03 Design of Steam Branch Pipes Steam mains are set up at the top of the steam branch, generally set up with a shut-off valve in the steam branch, in order to avoid liquid storage, the shut-off valve should be set in the horizontal piping, close to the main. Some steam piping requirements are more stringent than others, so steam branch pipes should not be connected to such piping, and branch pipes should not be connected to the π-compensator of the steam piping. If the branch pipe is connected to the main pipe at both ends of the π-compensator, the branch pipe should not be affected by the displacement of the steam main. In the case of thermal expansion, the steam main will cause displacement at the branch connection point, and the branch will not be subjected to excessive pressure or displacement. Normally, a two-valve manifold is used when the branch is connected to the steam main, but in order to allow leaks to be readily detected, the two-valve manifold should not be used to connect to other process piping from the steam branch or the steam main, but rather a three-valve manifold should be installed. Depending on the situation, traps, such as drain valves or traps, should be installed at the low point of the steam branch pipe. When installing traps on the pipeline, the pressure should be set according to the different levels of pressure in the pipeline corridor. 04 Design of Steam Condensate Piping Generally, steam piping and steam condensate piping are arranged on the same level on the pipe corridor. In order to prevent water hammer, a π-shaped compensator can be set up on the steam condensate piping. This π-row compensator is to be set in a horizontal direction, or the riser is designed as an inclined section. Condensate from steam traps with different pressures should be connected to their respective recovery mains. When the nominal diameter of the standpipe is not less than 50 mm, it can be connected directly to the top of the steam condensate recovery main. The printing plate selects a flange connection as the trap set in the steam condensate recovery system, and should not have a bag shape on the piping at the inlet of the trap. If the trap is lower than the steam condensate recovery main, a check valve should also be set behind the trap. When installing check valves, they should be installed on horizontal piping, near the steam condensate main. A flange connection should also be used for the check valve so that the steam piping can be easily blown out to remove the check valve. 05 Points to note when designing steam piping 1 Reasonable selection of pipe diameter When choosing the pipe diameter, according to the demand for steam. When the pipe diameter is too large, it will increase the investment, increase the heat loss, and also increase the condensate. When the pipe diameter is too small, it will cause the pressure of the steam use point, the steam flow is insufficient, and finally make the phenomenon of water hammer and erosion. Therefore, when selecting the pipe diameter, not too large or too small. 2 Stress requirements When arranging the pipeline, it must meet the requirements of stress and strictly carry out the calculation of stress. The setting of π-shaped compensator on the pipeline, the thrust of the compensator fixed point and the piping of the steam pipeline connected to the equipment should meet the requirements of stress, so that the efficiency of the design work can be improved. 3 to avoid water hammer phenomenon When the high-speed flow of water particles touch the pipeline installation, equipment or valves, will produce a certain amount of vibration and noise, which is known as the water hammer phenomenon. In order to avoid the phenomenon of water hammer, pay attention to the setup of the hydrophobic system, in addition to the sub ah connecting the branch pipe to take the steam, to be above the main pipe. The pipeline can not use too many branch pipes, shrinkage bends, etc.. In order to make the phenomenon of local sinking of the pipeline does not occur, set the pipeline support settings must be reasonable. The filter screen should be installed horizontally. All these details should be paid attention to so that the phenomenon of water hammer can be avoided and the quality and efficiency of steam piping design in chemical plants can be improved. Summary Chemical plant steam piping setup is a lot of strict requirements, but also pay attention to a lot of details, so as to ensure that the design is scientific and reasonable, improve the efficiency of the steam piping, when the steam piping function properly. Source: Reprint Disclaimer: This article is a network reproduced, the copyright belongs to the original author. If it involves copyright issues, please contact us, we will remove the content of the first time.

Acid mist purification tower, also known as: acid gas purification tower, acid mist purification tower, acid mist absorption tower, waste gas purification tower, and fiberglass acid mist purification tower. As an important waste gas treatment equipment, acid mist purification tower is already essential in industrial production. The following introduces the basic knowledge of acid mist absorption tower, mainly including its working principle, structural composition, and pH value. Working principle of acid mist absorption tower The acid mist absorption tower uses sodium hydroxide alkali solution to neutralize the hydrochloric acid mist. After the gas outside the tower body enters the tower body, it enters the packing layer through the perforated plate. There is spray liquid (sodium hydroxide solution) from the nozzle distribution on the packing layer, and a layer of liquid film is formed on the packing. When the gas flows through the packing gap, it contacts with the packing liquid film for absorption or neutralization reaction, and the gas continues to walk upward, After several absorption or neutralization, the gas is collected by the mist eliminator and discharged outside the tower through the air outlet. After treatment, the discharge amount of hydrochloric acid mist is 0.0069t/a (0.00144kg/h), and the emission concentration is 0.288mg/m3, which can meet the secondary standard in the "Comprehensive Emission Standard for Air Pollutants" (GB16297-1996). The measures taken are reasonable and feasible. Workflow: 1. After being compressed, the raw gas enters the condenser for cooling to around 50 ° C, and then enters the absorption tower for spray washing; 2. The washed gas passes through a degreasing filter to remove oil and impurities; 3. Then, after being pressurized by a fan, it is sent to a dryer for heating and dehydration to form dry gas (at a temperature of 100 ° C), and then sent to an absorbent storage tank for uniform mixing; 4. The evenly mixed liquid is pumped to the spraying device to form a liquid film and flows down the surface of the packing layer; 5. The organic matter in the liquid is adsorbed by activated carbon and removed; 6. The acid gas after desorption is neutralized with sodium hydroxide aqueous solution in the alkali washing section to a ph value of 7~9 (i.e. alkaline) and discharged out of the system. What is the appropriate pH value to control for the acid mist absorption tower? When the pH value is 7 to 7.5, it indicates that the purification capacity of the spray tower is good. When the pH value is 7.5, it indicates that the alkali solution in the spray tower is sufficient to neutralize the acidic gas in the tail gas. At this time, record the inspection date and the pH value of the spray solution in the tower. From a structural perspective, the absorption tower is generally divided into a cylinder, a flue gas inlet, and a flue gas outlet. Generally, the flue gas inlet is arranged in the middle of the absorption tower, and the flue gas outlet is arranged at the top of the absorption tower. From the perspective of functional zoning, the absorption tower cylinder can be divided into a slurry tank area, a spray area, and a demister area: the slurry tank area is generally located at the lower part of the absorption tower inlet, and the spray area and demister are located between the flue gas inlet and outlet. The flue gas outlet of the absorption tower can be of the top straight out type or the horizontal side out type. The conventional spray area is equipped with spray layers and nozzles, and depending on the desulfurization process, some absorption towers also have trays, Venturi bars, and other devices in the spray area. Source: Xianji Network Disclaimer: This article is reproduced online, and the copyright belongs to the original author. If there are copyright issues involved, please contact us and we will delete the content as soon as possible.

A, two media string each other (internal leakage) 1 Generate causes ① heat exchanger tube corrosion perforation, cracking. ② heat exchanger tube and tube plate expansion mouth (weld mouth) cracked. ③ floating head type heat exchanger floating head flange seal leakage. 2 processing methods ① replace or plug the leaky heat exchanger tube. ② heat exchanger tube and tube plate re-expansion (welding) or plugging. ③ tighten the bolts or replace the sealing gasket. Second, the flange at the seal leakage 1 Cause ① gasket under pressure, corrosion, deterioration. ② Insufficient bolt strength, loosening or corrosion. ③ flange rigidity and sealing surface defects. ④ flange is not flat or misaligned, gasket quality is not good. 2 Processing method ①Tighten the bolts and replace the gaskets. ②Upgrade the bolt material, tighten the bolt or replace the bolt. ③Replace the flange or deal with the defect. ④Reassemble or replace the flange and replace the gasket. Poor heat transfer 1 Causes ①Heat exchange tube scaling. ②Bad water quality, oil and microorganisms. ③Separator short circuit 2 Treatment method ①Chemical cleaning or jet cleaning of dirt and grime. ②Strengthen filtration, purify media and strengthen water quality management. ③Replace the tube box gasket or replace the bulkhead. Fourth, the resistance drop exceeds the allowable value 1 Cause Scaling inside the shell, inside and outside the tube 2 Treatment method Use jet or chemical cleaning scale V. Serious vibration 1 Generated by ① Resonance caused by the frequency of the medium. ② Resonance caused by external pipe vibration. 2 Treatment method ①Change the flow rate or change the inherent frequency of the pipe bundle. ② Reinforce the pipe to reduce vibration. Plate heat exchanger common failure causes analysis and processing methods Plate heat exchanger common failures are string liquid, external leakage, excessive pressure drop, the heating temperature can not meet the requirements of four aspects. A series of liquid 1 cause ① due to improper selection of plates resulting in plate corrosion cracks or perforations. ②The operating conditions do not meet the design requirements. ③ the residual stress of the plate after cold stamping and forming and the assembly of the clamping size is too small to cause stress corrosion. ④ Slight leakage at the leakage groove of the plate, resulting in the concentration of harmful substances in the medium corrodes the plate and forms a string of liquid. 2 Treatment methods ①Replace the cracked or perforated plate, and find the cracked plate in the field with the light transmission method. ② adjust the operating parameters so that they reach the design conditions. ③ heat exchanger maintenance assembly clamping size should meet the requirements, and not the smaller the better. ④ plate material reasonable match. Second, external leakage 1 cause ① clamping size is not in place, the size of each uneven (the size of each deviation should not be greater than 3 mm) or loose clamping bolts. ② Part of the gasket is out of the sealing groove, the main sealing surface of the gasket is dirty, the gasket is damaged or the gasket is aging. ③ Plate deformation, assembly misalignment caused by running gasket. ④ Cracks in the sealing groove area of the plate or the second sealing area. 2 Treatment method ① In a non-pressure state, re-clamp the equipment according to the clamping size provided by the manufacturer, the size should be uniform and the deviation of the clamping size should be no more than ±0.2N (mm) (N is the total number of plates), the parallelism between the two clamping plates should be kept within 2 mm. ② mark on the external leakage parts, and then the heat exchanger disassembly one by one to solve, reassemble or replace the gasket and plate. ③ Dismantle the heat exchanger and repair the deformed parts of the plates or replace them. In the absence of spare parts for the plates, the deformed parts can be temporarily removed and reassembled for use. ④ When reassembling the disassembled plates, the plate surface should be cleaned to prevent dirt from adhering to the gasket sealing surface. 3. Excessive pressure drop 1 Causes ① operation system pipeline is not normal blowing, especially the new installation system pipeline in many dirty things (such as welding slag, etc.) into the internal plate heat exchanger, due to the plate heat exchanger flow channel cross-sectional area is narrow, the heat exchanger within the sediment and suspended matter gathered in the corner hole and guide flow area, resulting in the flow channel area is greatly reduced, resulting in the main loss of pressure in this part. ② The plate heat exchanger is selected for the first time when the area is small, resulting in a high flow rate between the plates and the pressure drop is large. ③ plate heat exchanger running after a period of time, due to plate surface fouling caused by excessive pressure drop. 2 processing methods ① Clear the heat exchanger runners in the dirt or plate scaling, for the new operation of the system, according to the actual situation once a week cleaning. ② secondary circulation water is best used after softening treatment of soft water, the general requirements of the water quality concentration of suspended matter is not greater than 5 mg / L, impurity diameter is not greater than 3 mm, pH ≥ 7. When the water temperature is not greater than 95 ℃, Ca, Mg concentration should not be greater than 2 mmol / L; When the water temperature is greater than 95 ℃, Ca, Mg concentration should not be greater than 0.3 mmol / L, dissolved oxygen quality concentration should not be greater than 0.1 mg / L. ③ For the centralized heating system, the method of primary to secondary water replenishment can be used. Fourth, the heating temperature can not meet the requirements 1 Causes ①Insufficient flow of medium on the primary side, resulting in large temperature difference and small pressure drop on the hot side. ②Low temperature on the cold side, and low temperature at the cold and hot end. ③Multiple plate heat exchangers operating in parallel with uneven flow distribution. ④ internal scaling of the heat exchanger is serious. 2 Treatment methods ① Increase the flow rate of the heat source or increase the diameter of the heat source media pipeline. ② Balance the flow of multiple plate heat exchangers running in parallel. ③ disassemble the plate heat exchanger to clean the plate surface scale. I. Tube bundle failure 1, the corrosion of the tube bundle, wear caused by tube bundle leakage or blockage caused by scaling in the tube bundle failure Cooling water contains iron, calcium, magnesium and other metal ions and anions and organic matter, active ions will make the cooling water corrosion enhanced, the presence of metal ions cause hydrogen or oxygen depolarization reaction thus leading to tube bundle corrosion. At the same time, as the cooling water contains Ca2+ and Mg2+ ions, it is easy to scale at high temperatures for a long time and block the tube bundle. In order to improve the heat transfer effect and prevent the tube bundle from corrosion or blockage, the following methods are adopted: (1) Add scale inhibitor to the cooling water and clean it regularly. For example, the cooling water of the gas cooler uses an ion electrostatic processor or adds scale and corrosion inhibitor and algaecide to remove dirt and reduce the hardness of the cooling water, thus reducing the degree of tube bundle scaling. (2) Keep the fluid flow rate in the tube stable. If the flow rate increases, the thermal conductivity becomes larger, but the wear and tear will also increase accordingly. Minsheng Coal Chemical has modified the groundwater pump with frequency conversion, so that the pressure of the groundwater network is more stable, which improves the heat exchange effect of the heat exchanger and reduces the corrosion of the tube bundle. (3) Choose corrosion-resistant materials (stainless steel, copper) or increase the wall thickness of the tube bundle. (4) When the end of the tube is worn, the tube bundle can be protected by accessing synthetic resin etc. in the 200mm length of the inlet. 2.Vibration caused by the failure Causes of vibration include Vibration of the tube bundle caused by the vibration of pumps and compressors; pulsations generated by rotating machinery; The impact of high speed fluids (high pressure water, steam etc.) flowing into the bundle on the bundle. The following methods are often used to reduce the vibration of the tube bundle: (1) Minimising the number of starts and stops. (2) At the inlet of the fluid, install adjustment slots to reduce the vibration of the bundle. (3) Reduce the baffle spacing to reduce the amplitude of the bundle. (4) Minimise the aperture of the bundle through the baffle. Flange leakage into Flange leakage is due to the rise in temperature, fastening bolts heat elongation, in the fastening parts of the gap caused by. Therefore, after the heat exchanger is put into use, the flange bolts need to be re-fastened. The fluid in the heat exchanger is mostly toxic, high-pressure, high-temperature substances, once the leakage is easy to cause poisoning and fire accidents. Special attention should be paid to the following points in the daily work: Minimise the number of gaskets used and the use of metal gaskets; The use of methods of tightening gaskets under internal pressure; Use of easy fastening methods. Source: Reproduced Disclaimers: This article is reproduced on the internet and is the copyright of the original author. If copyright is involved, please contact us and we will remove the content as soon as possible.

In chemical plant production, the distillation tower is the most common and typical separation equipment, any person engaged in chemical production will not be unfamiliar with the distillation tower, but the common outstanding problems in the operation of the distillation tower, such as: liquid flooding, flooding tower, flushing tower phenomenon, the reasons are not very clear, the problem occurs when the response to the tower parameters changes are not sensitive, so often delay the solution to the problem, affecting the production of the device. A detailed analysis of the causes of the above mentioned problems, plus examples to show the parameter changes and incorrect operation when problems occur in production! Firstly, let's look at the most familiar phenomenon of liquid flooding ► What is liquid flooding? In a distillation column, the accumulation of liquid phase beyond the space in which it is located for various reasons is called liquid flooding. Liquid flooding can be divided into liquid flooding of the drop tube, liquid flooding of the mist entrainment, etc. Liquid flooding refers to the accumulation of liquid phase in the descending tube to the last layer of the tower plate. Mist entrainment liquid flooding refers to the open space on the tower plate of the gas phase flow rate reaches a certain speed, so that the liquid phase on the tower plate along with the rising gas phase into the upper layer of the tower plate. The operating condition when liquid flooding occurs is called the liquid flooding point. When designing a distillation tower, the liquid flooding rate must be maintained within a certain range to ensure the stable operation of the distillation tower. When liquid flooding begins, the pressure drop of the column rises sharply and the efficiency drops dramatically. Subsequently, the operation of the column is disrupted. ► What causes the liquid flooding phenomenon? 1. Liquid in the descending tube flows backwards back to the upper plate As the tower plate has resistance to the rising airflow, the pressure above the lower plate is higher than the pressure above the upper plate, and the height of the foam in the descending tube is equivalent to the static pressure head to overcome this pressure difference, the liquid can flow downwards. When the liquid flow rate remains the same and the gas flow rate increases, the pressure difference between the lower plate and the upper plate increases and the liquid level in the descending tube rises. If the gas flow rate increases to make the liquid in the descending tube rise to the top of the weir, the liquid in the tube will not only not flow down, but begin to backflow back to the upper plate, the plate will begin to accumulate liquid; to operate when the liquid is constantly sent from the tower, and finally will make the whole tower full of liquid. On the formation of the liquid flood. If the gas flow rate is certain and the liquid flow rate is increased, the resistance of the liquid through the descending tube increases, as well as the plate on the liquid layer thickening, so that the pressure difference between the plate up and down increases, will make the liquid level in the descending tube rise, thus leading to liquid flooding. 2.Excess liquid foam entrained to the upper plate Air entrainment to the upper plate of liquid foam, can make the plate on the liquid layer thickening, normal increase to a certain extent, the thickening of the liquid layer will be significant up (the amount of liquid on the plate increased, bubbles add more, increase). Air flow through the thickened liquid layer of the liquid foam brought out and further increase. This excess liquid foam entrainment so that the top of the foam layer and the distance between the bottom of the upper plate is reduced, liquid foam entrainment continues to increase, large droplets are easy to spray directly to the upper plate, foam can also be bubbled to the upper plate, and finally the whole tower is filled with liquid. ► Liquid flooding phenomenon is divided into several kinds? 1, the bottom of the tower and the top of the tower pressure difference increases; 2, the temperature difference between the bottom of the tower and the top of the tower is reduced; 3.The level of the reflux tank at the top of the tower decreases; 4, the product yield at the bottom of the tower is reduced; 5.The product quality at both the top and bottom of the tower is not satisfactory. ► What methods are used to deal with it? 1.Refurbishing the bottom gap of the lowering plate; 2.Reducing the amount of rising steam; 3.Reduce the amount of feed; 4.Reduce the amount of steam, return flow. Note: Of the above two causes of liquid flooding, the more common one is excessive liquid foam entrainment. The second common outstanding problem is flooding the tower In the distillation process, from a certain tower plate up the liquid gradually accumulated, to fill part of the tower section, so that the rising gas is blocked, gas, liquid two-phase heat transfer process can not be carried out properly, this is called flooding tower. ► The phenomenon of flooding tower is: tower top temperature drop; reflux tank liquid level drop; tower bottom liquid level and pressure increase. ► The causes of the flooding of the tower occur for several reasons: 1.Sinker tube blocked, reflux liquid can not flow down. Start iron chips, welding slag and other debris, the normal production of equipment corrosion deposits, or solid precipitation in the liquid, the solution of the self-polymer, are prone to cause the descending liquid tube blockage. 2, the amount of liquid is too large, so that the descending liquid tube overload. ► The treatment methods are these two: 1, appropriate to reduce the amount of feed and return flow. 2, such as equipment failure, then shut down to deal with. The last common problem is the flushing tower In normal operation of a distillation tower, the gas-liquid phase load is relatively stable. When the gas-liquid phase load are too large, the gas through the tower plate pressure drop increases, will make the descending liquid tube in the liquid surface height increases; liquid phase load increases, the liquid surface height on the exit weir increases. When the liquid is filled with the whole descending tube, the upper and lower tower plate is connected into one, fractionation is completely destroyed, there will be a flushing tower. ► The reason for flushing tower is: all the factors that form the tower gas-liquid phase load is too large can cause flushing tower, such as the processing volume of crude oil, the nature of the raw material is too light, crude oil into the tower water content, tower bottom blowing steam volume, into the material temperature is too high, reflux interruption or uneven distribution, etc.. ► Phenomenon: the occurrence of flushing tower, because of the tower fractionation effect becomes bad, destroy the normal mass transfer heat transfer, resulting in the tower top temperature, pressure, side line distillation outlet temperature, reflux temperature are rising, tower low liquid level suddenly drop, distillation oil colour becomes black. ► The principle of processing is to reduce the vapour-liquid load, that is, to reduce the return flow and the amount of steam heated at the bottom of the tower, if the processing volume is too large, can reduce the amount of feed. If necessary, you can interrupt the feed, turn off the bottom heating steam and wait for the temperature of each layer of the tower tray to fall back to below the normal value, then reheat and feed. ► Data analysis As seen by the changes in the stabilisation tower parameters: a) The separation effect of the tower has deteriorated and the purity of the product at the bottom of the tower has decreased, resulting in the sensitive plate temperature remaining below the normal production index with increased steam volume; (b) With the same pressure at the top of the tower, the return flow rate is increased and the temperature of the tower plate under the return flow is still higher than the normal index value, indicating that the purity of the product at the top of the tower has decreased and the separation effect has become worse; (c) sensitive plate (the third layer of the tower plate) and the 21st layer of the tower plate temperature difference is significantly smaller, indicating that the lower tower plate light components increase, the upper tower plate regrouping increased, while the bottom of the tower level can still be controlled normally, the tower can be judged to have a serious liquid flooding phenomenon. If the tower is flushed, the level at the bottom of the tower will decrease rapidly, which is the obvious difference between flushing and liquid flooding. ► What causes it? For a distillation tower that has been designed and is in normal operation, with little change in the composition of the raw material, when a washout or liquid flooding occurs, it should be analysed primarily from an operational point of view. As can be seen from the comparative data in the above graph when the tower is stabilised with liquid flooding, the stabilised tower return flow and the amount of steam heated at the bottom of the tower are both higher than normal, which is the most common operation leading to liquid flooding. Operators are not experienced and do not have a deep understanding of distillation tower operation, when the sensitive plate temperature is low, increase the amount of heating steam at the bottom of the tower, when the tower top temperature is high and increase the return flow, so repeatedly, resulting in the amount of heating steam and return flow are too large, the gas-liquid phase load are significantly more than the design load of the tower, resulting in liquid flooding, the tower gas-liquid balance is damaged. After the liquid flooding phenomenon in this stabilised tower, the return flow rate and the amount of steam at the bottom of the tower were readjusted, but after 16 hours the stabilised tower still did not reach a normal equilibrium. Finally, measures were taken to turn off the heating steam, stop feeding and reduce the temperature, and the tower was put back into operation to adjust properly. Source: Reprint Disclaimers. 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