A distributed tubular reactor

Abstract

This invention discloses a distributed tubular reactor, comprising a reactor body and a material inlet head, and several heat exchange tubes disposed within the reactor body for conveying material from the material inlet head upwards. The material inlet head is equipped with a material guiding device, which diverts the material entering the inlet head and distributes it evenly to the ends of each heat exchange tube. This invention solves the problem of material collapse that often occurs when the liquid level enters the prepolymerization reactor, thereby ensuring the stability of the entire polycondensation reaction process and the product indicators.

Description

Technical Field

[0001] This invention relates to the field of reactors, and more specifically to a distributed tubular reactor. Background Technology

[0002] Polyester (PET), also known as polyester fiber, is a widely used synthetic fiber. Its applications span textiles, clothing, automotive accessories, industrial products, protective clothing, and many other areas, playing a vital role in national economy and people's livelihood. Currently, industrial production mainly involves the esterification, prepolymerization, and final polymerization of purified terephthalic acid and ethylene glycol to prepare polyester melt. This melt then undergoes a series of physical processes, including booster pumps, melt coolers, spinning boxes, ring blowing (side blowing), oiling, and winding, to form polyester filaments or staple fibers. Currently, the mainstream polyester plants in the chemical fiber industry that produce melt-spinning products can be categorized as follows: the China Textile Academy's four / five-reactor process plant, the Contex three-reactor process plant, and the Juyou three-reactor process plant. Compared to the China Textile Academy's four / five-reactor process plant, the Contex and Juyou three-reactor process plants are characterized by shorter reaction times, a plug flow material flow, fewer moving parts in the material transport process, and greater energy efficiency. Due to the high efficiency of their reactors, the finished products produced are highly differentiated, have excellent performance, and offer flexible styles, making them popular with the market and consumers.

[0003] In the prepolymerization stage of the three-reactor process units of Contex and Juyou, the reactor mainly consists of a lower tubular reactor and an upper tray reactor. The esterified products (BHET) and additives (catalyst, titanium dioxide, trimonomer, diethylene glycol, etc.) generated in the esterification stage are fed into the lower end of the tubular reactor by a gear pump. The material flows through the tube side and the heat transfer oil flows through the shell side, where a large amount of heat exchange takes place, heating the material to above 280 degrees Celsius in a short time. Then, it enters the vacuum-controlled upflow tray prepolymerization reactor from the upper part of the tubular reactor. Under the combined action of high temperature, additives, and vacuum, the esterified products undergo a violent prepolymerization reaction, releasing small ethylene glycol molecules to form prepolymers with a degree of polymerization of about 12-20. This creates condensation conditions for further reactions in the final polymerization. It can be seen that the tubular reactor plays a crucial role in the prepolymerization stage.

[0004] In actual production at Contex and Juyou's three-reactor process units, abnormal and sudden drops in the prepolymer reactor level frequently occur, accompanied by drastic fluctuations in the material temperature at the prepolymer heater outlet. This phenomenon is known in the industry as "material collapse." As is well known, in continuous polyester production units, liquid level and temperature are crucial parameters, as they are key factors determining the stability of product indicators. The occurrence of material collapse leads to abnormal prepolymerization reactions, significant changes in the degree of polymerization, and large fluctuations in prepolymer viscosity. The feed from prepolymerization to final polymerization becomes unstable, ultimately causing changes in the entire polycondensation reaction process and fluctuations in material viscosity. In severe cases, it can even lead to changes in product indicators and production accidents resulting in product degradation, becoming a long-standing problem plaguing the industry.

[0005] In response to this phenomenon, our R&D and production technology teams analyzed various causes related to material collapse. After years of production practice and elimination, they finally identified the cause as an unreasonable design of the current tubular reactor: after the material enters the head through the straight pipe, the short distance and dwell time at the head result in limited dispersion. In addition, the unreasonable arrangement of the tubes inside the reactor and the small length-to-straightness ratio of the tubular reactor cause most high-pressure materials to preferentially enter the tubes directly in the center, while little or no material is distributed in the tubes near the periphery. This distribution is more common when the plant's capacity is relatively low. This situation leads to the heat exchange area of ​​the tubular reactor not being fully utilized, resulting in poor thermal efficiency. To reach the reaction temperature, a higher heat transfer medium temperature is required. During normal production, especially in cationic polyester plants, as the production cycle lengthens, the flowability of the material in the central tubes changes (mainly due to material buildup on the inner wall of the central tubes at high temperatures), increasing resistance. This buildup gradually accumulates to a certain level, causing the material concentrated in the central tubes to suddenly disperse and fill the empty or low-material tubes on the periphery. Since the esterification flow rate into the tube reactor is constant, this results in a sudden decrease in the amount of material entering the prepolymerization reactor, causing a sudden drop in liquid level (material collapse). Under fixed heat transfer medium temperature conditions, when the empty tubes are filled with material, the heat exchange area suddenly increases, and the material temperature rises instantly. Due to its suddenness and unpredictability, this causes prepolymerization reaction disturbances, delayed regulation, and long recovery times, ultimately leading to severe product degradation. After the material pressure is released, the material in the tubes continues to accumulate over time. In large-scale continuous polyester plants, this material collapse phenomenon can even occur repeatedly at a certain point, causing significant economic losses to the company. Summary of the Invention

[0006] In order to solve one or more technical problems existing in the prior art, the purpose of this application is to provide a distributed tubular reactor that can solve the problem of material collapse that often occurs when the liquid level enters the prepolymerization reactor, thereby ensuring the stability of the entire polycondensation reaction process and the indicators of the produced products.

[0007] To address the aforementioned technical problems, the objective of this application is achieved through the following technical solution:

[0008] A distributed tube reactor includes a tube reactor body and a material inlet head, and a plurality of heat exchange tubes disposed in the tube reactor body for conveying material in the material inlet head upward. The material inlet head is provided with a material guiding device, and the material entering the material inlet head is diverted by the material guiding device and evenly distributed to each of the heat exchange tube ends.

[0009] Preferably, the material inlet of the material inlet end cap adopts a variable diameter expansion pipe structure that gradually increases in size from bottom to top.

[0010] This invention changes the material inlet at the bottom of the material inlet end cap from a straight pipe to a variable diameter expansion pipe, which facilitates the dispersion and release of material pressure before it enters the material inlet end cap, thereby reducing the material flow rate and achieving initial diffusion distribution of the material, reducing impact pressure, and effectively solving the problem of limited dispersion of material after it enters the material inlet end cap from the existing straight pipe due to the short distance and short dwell time at the material inlet end cap.

[0011] Preferably, the material guiding device includes a diversion plate and a guide plate. The guide plate is provided with guide holes. After the material entering from the material inlet end cap is diverted by the diversion plate, part of the material is guided to one end of the outer ring heat exchange tube along the annular channel formed between the diversion plate and the inner wall of the material inlet end cap. Another part flows upward from the hole in the middle of the diversion plate and is diverted again by the guide plate. Part of the material in the second diversion flows upward along the channel formed between the diversion plate and the guide plate, and another part flows upward through the guide holes. The diversion plate and the guide plate evenly distribute the incoming material to one end of each of the heat exchange tubes.

[0012] Preferably, the diversion plate is fixed to the inner wall of the material inlet end cap by a plurality of support frames, the guide plate is fixed to the diversion plate by a support frame, and the diversion plate adopts a funnel-shaped structure with an arc similar to that of the material inlet end cap.

[0013] The material guiding device consists of a diversion plate, a support frame, and a guide plate with guide holes. The diversion plate adopts a funnel-shaped structure with an arc similar to the inside curvature of the material inlet end cap. The diversion plate is fixed to the inner wall of the heat medium jacket inside the material inlet end cap using the support frame. This allows the material to flow more smoothly to the lower end of the outer heat exchange tubes after entering the material inlet end cap, thus preventing material collapse due to insufficient material supply in the outer heat exchange tubes before reaching the prepolymerization reactor. The guide plate with guide holes is located in the center of the opening of the diversion plate. A certain distance is formed between the support frame and the feed hole in the center of the diversion plate. After the material enters the diversion plate directly, it undergoes secondary diversion, allowing a portion of the material to be directly conveyed to the middle through the guide holes. The material flows from the lower end of the heat exchange tubes in one area to the lower end of the heat exchange tubes located between the middle and outer areas, while another portion of the material can be guided along the channel between the distribution plate and the guide plate. This effectively guides the material entering the material inlet head and distributes it evenly to the lower ends of the heat exchange tubes in different areas, avoiding the problem of excess material in the middle and less supply closer to the periphery when the material is transported through the heat exchange tubes due to direct material flow. This also prevents material collapse. In particular, when the funnel-shaped distribution plate is combined with the material inlet at the bottom of the material inlet head of the variable diameter expansion pipe structure, the material pressure in the pipe can be dispersed and released before entering the material inlet head, achieving rapid diversion and reducing the impact pressure entering the distribution plate, allowing the material to be transported more evenly and gently along the heat exchange tubes.

[0014] Preferably, the material inlet end cap has one end cap heat medium inlet and two end cap heat medium outlets. The end cap heat medium inlet is located on the lower side of the material inlet end cap, and the end cap heat medium outlets are two in number and located on the upper sides of the material inlet end cap. The side wall of the material inlet end cap forms an outer jacket layer of a heat medium dual-outlet insulation system through the end cap heat medium inlet and the end cap heat medium outlets.

[0015] The heat medium outlet of the material inlet end cap is designed from a single loop to a dual loop, which makes the heat distribution of the material inlet end cap more uniform and the material flow better.

[0016] Preferably, the heat exchange tubes are arranged in an equilateral triangle pattern.

[0017] The heat exchange tubes are designed to be arranged in an equilateral triangle pattern instead of the traditional diamond pattern; this has the advantage of optimizing the fluid distribution and heat transfer inside the reactor, thereby improving the reaction efficiency and reducing energy consumption.

[0018] Preferably, without reducing the heat exchange area, the area ratio of the heat exchange tubes in the central region is 20%, and the ratio of the diameter of the heat exchange tubes in the central region to the diameter of the heat exchange tubes in the outer region is 0.8:1.

[0019] By reducing the diameter of the heat exchange tubes in the central region, the amount of material entering the central region can be limited, facilitating flow distribution. In particular, when the heat exchange tube area in the central region accounts for 20% and the diameter of the heat exchange tubes in the central region is 0.8 times that of the outer region, the amount of material entering the central region can be effectively limited. Without significantly affecting the overall heat exchange efficiency of the heat exchanger, the material can be distributed to the surrounding areas, facilitating more stable flow distribution.

[0020] Preferably, the guide plate is located below the heat exchange tube in the central region, and the diameter of the guide hole is 0.5 to 0.6 times the diameter of the heat exchange tube.

[0021] Preferably, the tube reactor body includes a reactor shell, an upper tube sheet and a lower tube sheet disposed at the upper and lower ends of the reactor shell, a plurality of spaced tubes, baffles and tie rods disposed inside the reactor shell, a tube reactor heat medium inlet and a tube reactor heat medium outlet disposed on the side of the reactor shell, and the two ends of the heat exchange tubes are respectively disposed between the lower tube sheet and the upper tube sheet.

[0022] The heat exchange tubes pass through the lower and upper tube sheets at both ends and are fixed by the lower and upper tube sheets. The ends of the heat exchange tubes are sealed to the lower and upper tube sheets, allowing the material to flow upwards along the inside of the heat exchange tubes. The heat transfer medium, after entering the reactor shell, flows along the outer wall of the heat exchange tubes. Several baffles in the tube reactor body are fixed at equal intervals in the reactor shell using spacer tubes and tie rods. The upper end of the material inlet end cap is connected to the lower tube sheet using studs and sealed with a spiral wound gasket. Insulation rings are provided on the outside of both the reactor shell and the material inlet end cap. The upper tube sheet is connected to the lower flange of the prepolymer reactor using studs.

[0023] Preferably, the length L / diameter d ratio of the reactor shell is 2.686.

[0024] Increasing the length-to-straightness ratio (L / d) of the tube reactor, without changing the heat exchange area, from the original 2.31 to 2.686, and changing the structural shape from "short and stout" to "slender and long", is more conducive to the uniform distribution of materials.

[0025] Preferably, the inlet of the tubular reactor for the heat medium is provided with an anti-impact plate.

[0026] An anti-impact plate is designed at the heat medium inlet of the tube reactor to mitigate the impact of high-pressure heat transfer oil on the tubes after the heat medium enters the tube reactor.

[0027] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0028] During the material transport process in the prepolymerization stage, by adding a material guiding device inside the material inlet end cap, the material entering the material inlet end cap can be diverted by the material guiding device and evenly distributed to each heat exchange tube end in the tube reactor. This allows the material in the material inlet end cap to be evenly transported by the heat exchange tubes in each area to the tray reactor at the top of the reactor. This solves the problem in existing reactors where, due to unreasonable tube arrangement design, most of the high-pressure material preferentially enters the heat exchange tubes directly in the center, while little or no material is distributed to the heat exchange tubes near the periphery. Especially when the plant capacity is relatively low, it can also avoid uneven distribution, thus making full use of the heat exchange area of ​​the tube reactor, resulting in high thermal efficiency and stable temperature of the supplied heat medium.

[0029] Especially when producing cationic products, it can effectively avoid the problem of changes in the fluidity of materials due to increased resistance in the heat exchange tubes in the central area, avoid the problem of sudden drop in liquid level due to different feeding pressures of materials entering the prepolymerization reactor, and also avoid the problem of excessive instantaneous temperature fluctuations of materials under fixed heat medium temperature conditions, thus ensuring the stability of the entire polycondensation reaction process and the indicators of the produced products. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the internal structure of the present invention;

[0031] Figure 2 This is a plan view showing the distribution of heat exchange tubes in this invention;

[0032] In the diagram: 1. Heating medium inlet of the end cap; 2. Material inlet end cap; 3. Material guiding device; 31. Diverter plate; 32. Guide plate; 33. Guide hole; 34. Support frame; 4. Heating medium outlet of the end cap; 5. Spiral wound gasket; 6. Tube reactor body; 61. Reactor shell; 62. Baffle plate; 63. Spacing tube; 64. Tie rod; 65. Upper tube sheet; 66. Lower tube sheet; 7. Heat exchange tube; 71. Heat exchange tube in other areas; 72. Heat exchange tube in the central area; 8. Heating medium inlet of the tube reactor; 9. Anti-impact plate; 10. Insulation ring; 11. Heating medium outlet of the tube reactor; 12. Material inlet; 13. Central area. Detailed Implementation

[0033] The present application will now be further described in conjunction with the accompanying drawings and specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments.

[0034] In the description of this application, it should be understood that the terms "upper", "lower", "left", "right", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0035] The terms "first," "second," etc., used in this application are used to distinguish similar objects and not to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that embodiments of this application can be implemented in orders other than those illustrated or described herein, and the objects distinguished by "first," "second," etc., are generally of the same class, without limiting the number of objects; for example, a first object can be one or more. Furthermore, in the specification and claims, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0036] Example 1: Due to design flaws in the lower tubular reactor of the polyester unit in melt spinning enterprises in the chemical fiber industry, abnormal sudden drops in the prepolymer reactor level frequently occur, accompanied by drastic fluctuations in the material temperature at the prepolymer heater outlet, resulting in a problem known in the industry as material collapse. The structure of the tubular reactor was redesigned. The improved distributed tubular reactor consists of a tubular reactor body 6 and a material inlet end cap 2. For example... Figure 1As shown, the tubular reactor body 6 consists of a cylindrical reactor shell 61, an upper tube sheet 65 and a lower tube sheet 66 installed at the upper and lower ends of the reactor shell 61, heat exchange tubes 7 vertically installed between the lower tube sheet 66 and the upper tube sheet 65, and several parallel baffles 62 installed inside the reactor shell 61. The baffles 62 in the tubular reactor body 6 are fixed at equal intervals in the reactor shell 61 by spacer tubes 63 and tie rods 64. The two ends of the heat exchange tubes 7 pass through the lower tube sheet 66 and the upper tube sheet 65 respectively and are sealed and fixed, so that the material flows from bottom to top along the inside of the heat exchange tubes 7. On the side of the reactor shell 61, there are a tubular reactor heat medium inlet 8 and a tubular reactor heat medium outlet 11. The heat medium flows into the reactor shell 61 from the tubular reactor heat medium inlet 8 located at the upper end of the side of the reactor shell 61, surrounds the heat exchange tubes 7, and then flows out from the tubular reactor heat medium outlet 11, thereby realizing heat exchange. When the material enters the material inlet head 2, it is in an upward rushing state. This inevitably leads to a situation where the heat exchange tubes in the middle region experience a higher impact pressure, causing the material to preferentially flow upwards from the middle region. The upward pressure decreases as the material moves closer to the periphery, and the remaining material preferentially enters the heat exchange tubes 7 with higher pressure, eventually flowing into the outer heat exchange tubes 7. Under these circumstances, the pressure of the material entering the tray reactor through the heat exchange tubes in the middle region is also higher than that in the outer region. This causes the material to collapse due to the pressure difference. Especially when the unit's capacity is relatively low, uneven material distribution will occur, resulting in unstable heat exchange efficiency in the tubular reactor, leading to low thermal efficiency and unstable temperature of the supplied heat medium. Therefore, a material guiding device 3 was added inside the material inlet head 2. The material guiding device 3 can divert the material that rushes into the material inlet head 2 and distribute it evenly to the ends of each heat exchange tube 7 in the tube reactor. This allows the material in the material inlet head 2 to be evenly transported by the heat exchange tubes 7 in each area to the tray reactor at the top of the reactor. This solves the problem that in existing reactors, due to the unreasonable arrangement of the tubes, most of the high-pressure material preferentially enters the heat exchange tubes 7 that are arranged in the center, while little or no material is distributed to the heat exchange tubes 7 near the periphery. Especially when the production capacity of the device is relatively low, it can also avoid uneven distribution, so that the heat exchange area of ​​the tube reactor can be fully utilized, the thermal efficiency is high, and the temperature of the supplied heat medium is stable. Especially when producing cationic products, it can effectively avoid the problem of changes in the fluidity of materials due to increased resistance in the heat exchange tube 72 in the central area, avoid the problem of sudden drop in liquid level due to different feeding pressures of materials entering the prepolymerization reactor, and also avoid the problem of excessive instantaneous temperature fluctuations of materials under fixed heat medium temperature conditions, thus ensuring the stability of the entire polycondensation reaction process and the indicators of the produced products.

[0037] A further improvement involves fixing the baffles 62 within the reactor shell 61 using a combination of fixed-distance tubes and tie rods 64. This creates a staggered and parallel distribution of the baffles 62, allowing the heat medium to flow slowly downwards after entering the tube reactor from the heat medium inlet 8, where it is limited and guided by multiple baffles 62. This results in a longer residence time of the heat medium above each baffle 62, leading to higher heat exchange efficiency and preventing the problem of reduced heat exchange temperature caused by excessive residence time of cooled heat medium after rapid filling of the entire reactor shell 61. The upper tube sheet 65 is connected to the lower flange of the prepolymerization vessel using studs, and the upper end of the material inlet head 2 is connected to the lower tube sheet 66 using studs and sealed with a spiral wound gasket 5, simplifying the connection process. Insulation rings 10 are installed on the outer sides of both the reactor shell 61 and the material inlet head 2, ensuring higher heat exchange efficiency, preventing excessively high temperatures in the production environment, and avoiding burns to personnel from the outer shell of the tube reactor.

[0038] A further improvement is made to the material guiding device 3, which is mainly composed of a diversion plate 31 and a guide plate 32 with guide holes 33. The diversion plate 31 adopts a funnel-shaped structure with an arc similar to that of the material inlet end cap 2. The top of the diversion plate 31 has a certain height gap with the lower tube plate 66. The guide plate 32 with guide holes 33 is generally flush with the upper opening of the diversion plate 31. The diversion plate 31 is suspended and fixed inside the material inlet end cap 2 by 3-4 support frames 34, and the guide plate 32 is suspended and fixed inside the material inlet end cap 2 by 3-4 support frames 34. The frame 34 is suspended and fixed inside the distribution plate 31, so that after the material enters from the material inlet end cap 2, a portion of the material is diverted through the lower end of the distribution plate 31. Some of the upward-flowing material continues upward into the distribution plate 31, while the remaining material is diverted through the distribution plate 31 and guided along the annular channel space formed between the distribution plate 31 and the inner wall of the material inlet end cap 2 to one end of the outer ring heat exchange tube 7. This prevents the outer ring heat exchange tube 7 from being unable to transport the material. The material is fed directly into the distribution plate 31. A portion of the material flows upward along the inner wall of the distribution plate 31, while a portion continues to flow upward. The material impacting the guide plate 32 is partially transported through the guide holes 33 to the heat exchange tube 7 in the middle area, while the remaining portion, blocked by the guide plate 32, fills the interior of the distribution plate 31 and continues to flow upward along the channel formed between the guide plate 32 and the distribution plate 31. This provides targeted feeding to the heat exchange tube 7 between the middle and outer areas, ensuring that the material is rationally distributed to the lower end of the heat exchange tube 7 in different areas. This avoids excessive pressure in the middle of the heat exchange tube 7 while insufficient pressure in the outer areas leads to insufficient material supply. It also prevents abnormal drops in the prepolymer tank level due to insufficient material supply from the outer heat exchange tube 7, and avoids low heat exchange efficiency caused by uneven heat exchange.

[0039] Example 2: Due to the unreasonable design of the tubular reactor, after the material enters the material inlet head 2 through the straight pipe, the short distance and short dwell time of the material inlet head 2 result in limited dispersion, making it difficult for the material to be transported to the lower end of the outer heat exchange tube 7 in a timely manner. Even with the addition of the material guiding device 3, it is still impossible for the material to flow along the inner wall of the material inlet head 2 to the outermost heat exchange tube 7 in a timely manner after entering the material inlet head 2. Therefore, in order to solve this problem, the material inlet 12 of the material inlet head 2 adopts a variable diameter expansion pipe structure that gradually increases in size from bottom to top.

[0040] This invention changes the material inlet 12 at the bottom of the material inlet end cap 2 from a straight pipe to a variable diameter expansion pipe. When the material enters, it can be guided through the variable diameter expansion pipe, allowing some of the material to directly impact the channel formed by the inner wall of the material inlet end cap 2 and the distribution plate 31. This allows the material to flow towards the outer heat exchange tube 7 under pressure, facilitating the dispersion and release of material pressure before entering the material inlet end cap 2, reducing the material flow velocity, and thus achieving initial diffusion and distribution of the material. This reduces the impact pressure and effectively solves the problem of limited dispersion caused by the short distance and short dwell time of the material entering the material inlet end cap 2 from the existing straight pipe. The lower opening of the diversion plate 31 extends in an arc shape into the material inlet 12, and the diameter of the lower port of the diversion plate 31 is smaller than the inner diameter of the material inlet 12. When the funnel-shaped diversion plate 31 is combined with the material inlet 12 at the bottom of the material inlet end cap 2 of the variable diameter expansion pipe structure, the material pressure in the pipeline can be dispersed and released before entering the material inlet end cap 2 to achieve rapid diversion, reduce the impact pressure entering the diversion plate 31, increase the material pressure flowing along the outside of the diversion plate 31, and make the material more uniform and gentle to be pressurized and transported along the heat exchange tubes 7 in different areas.

[0041] Example 3: Because the existing material inlet end cap 2 only has one end cap heat medium inlet 1 and one end cap heat medium outlet 4, the flow of heat medium in the jacket is restricted. This results in areas where the heat medium flows along the direction of the end cap heat medium inlet 1 and the end cap heat medium outlet 4 being fully heated, while areas with low heat medium replacement efficiency have relatively lower temperatures, leading to uneven heating. The side with lower temperature is prone to reducing material flowability. Therefore, the flow trajectory of the heat medium is redesigned. The material inlet end cap 2 has one end cap heat medium inlet 1 and two end cap heat medium outlets 4. The end cap heat medium inlet 1 is located on the lower side of the material inlet end cap 2, and the end cap heat medium outlets 4 are two and located on the upper sides of the material inlet end cap 2. The side wall of the material inlet end cap 2 forms an outer jacket layer of a heat medium dual-outlet insulation system through the end cap heat medium inlet 1 and the end cap heat medium outlets 4.

[0042] By designing the head heat medium inlet 1 and two head heat medium outlets 4, the heat medium flow is transformed from a single loop to a double loop. With a head heat medium outlet 4 symmetrically designed on both sides, the heat medium in the interlayer can be replaced more evenly and quickly, avoiding the problem of the heating temperature dropping due to untimely replacement of some heat medium. This makes the heat distribution of the material inlet head 2 more uniform and the material flow better.

[0043] Example 4: Existing tube reactors typically have a length (L) / straightness (d) ratio of 2.31, and the heat exchange tubes 7 are arranged in a rhomboid pattern with equal diameters for each tube. Most high-pressure materials preferentially enter the centrally located heat exchange tubes 7, leaving little or no material in the outermost tubes. Even after improvements in Examples 1-3, it's difficult to avoid the problem of slightly higher material flow rates in the central tubes 7 compared to the outer ones, especially at lower plant capacities. This distribution pattern leads to insufficient utilization of the heat exchange area in the tube reactor, hindering optimal thermal efficiency. The solution is to change the traditional rhomboid arrangement of the heat exchange tubes 7 to an equilateral triangular arrangement. Figure 2 As shown, this design optimizes the fluid distribution and heat transfer within the reactor, thereby improving reaction efficiency and reducing energy consumption. Simultaneously, without reducing the heat exchange area, reducing the diameter of the heat exchange tube 72 in the central region limits the amount of material entering the central region 13, facilitating flow distribution. Specifically, when the area of ​​the heat exchange tube 72 in the central region accounts for approximately 20%, and its diameter is about 0.8 times that of the heat exchange tubes 71 in other regions, the amount of material entering the central region 13 is effectively limited. This ensures that the material delivered to the prepolymerization reactor is more uniform, both in the center and at the periphery, preventing situations where the material supply in the center is significantly greater than that in the periphery. Without significantly impacting the overall heat exchange efficiency of the heat exchanger, this design also achieves the goal of distributing material to the surrounding areas, facilitating more stable flow distribution. Meanwhile, the guide plate 32 is located below the heat exchange tube 72 in the central area. If the diameter of the guide hole 33 is too large, it is easy for the material to directly impact the heat exchange tube 7, resulting in excessive impact pressure on a certain heat exchange tube 7. Therefore, when designing the diameter of the guide hole 33, its diameter is set to 0.5 to 0.6 times the diameter of the heat exchange tube 7. This ensures that even if the guide hole 33 is directly facing the lower end of the heat exchange tube 7, it will not cause a 100% impact feeding situation, and the material pressure in the heat exchange tube 7 can be effectively and stably controlled.

[0044] A further improvement is made by increasing the length L / diameter d ratio of the reactor shell 61 to 2.686; increasing the length L / diameter d ratio of the tube reactor from 2.31 to 2.686 without changing the heat exchange area, and changing the structural shape from a "short and stout" type to a "slender and long" type, which is more conducive to the uniform distribution of materials. Furthermore, an anti-impact plate 9 is installed at the heat medium inlet 8 of the tube reactor to mitigate the impact of high-pressure heat transfer oil on the tubes after the heat medium enters from the heat medium inlet 8, ensuring a more stable heat exchange efficiency of the heat medium within the entire reactor shell 61 and preventing localized overheating. The anti-impact plate 9 can be a honeycomb plate structure, generally fixed at certain intervals by a bracket at the heat medium inlet 8 of the tube reactor.

[0045] The above improvements effectively solve the problem of uncontrollable fluctuations in liquid level and temperature caused by unreasonable design in existing tubular reactors. This stabilizes the degree of polymerization, prepolymer viscosity, and the feed from prepolymer to final polymerization during the production process, thereby ensuring stable product specifications and preventing production accidents that could lead to product degradation.

[0046] The above embodiments are merely preferred embodiments of this application and should not be construed as limiting the scope of protection of this application. Any non-substantial changes and substitutions made by those skilled in the art based on this application shall fall within the scope of protection claimed by this application.

Claims

1. A distributed tubular reactor, comprising a tubular reactor body (6) and a material inlet head (2), and a plurality of heat exchange tubes (7) disposed within the tubular reactor body (6) for conveying material from the material inlet head (2) upwards, wherein the material enters a prepolymerization reactor via the heat exchange tubes (7), characterized in that: The material inlet end cap (2) is provided with a head heat medium inlet (1) and two head heat medium outlets (4). The head heat medium inlet (1) is located on the lower side of the material inlet end cap (2). The head heat medium outlets (4) are two and located on both sides of the upper end of the material inlet end cap (2). The side wall of the material inlet end cap (2) forms a heat medium double outlet insulation system outer jacket layer through the head heat medium inlet (1) and the head heat medium outlets (4). The material inlet end cap (2) is provided with a material guiding device (3). The material entering the material inlet end cap (2) is diverted by the material guiding device (3) and evenly distributed to each of the heat exchange tubes (7). Without reducing the heat exchange area, the area of ​​the heat exchange tubes (7) in the central region (13) accounts for 20%.

2. A distributed tube reactor according to claim 1, characterized in that: The material inlet (12) of the material inlet end cap (2) adopts a variable diameter expansion pipe structure that gradually increases from bottom to top.

3. A distributed tube reactor according to claim 2, characterized in that: The material guiding device (3) includes a diversion plate (31) and a guide plate (32). The guide plate (32) is provided with a guide hole (33). After the material entering from the material inlet end cap (2) is diverted by the diversion plate (31), part of it is guided along the annular channel formed between the diversion plate (31) and the inner wall of the material inlet end cap (2) to one end of the outer ring heat exchange tube (7). Another part flows upward from the hole in the middle of the diversion plate (31) and is diverted again by the guide plate (32). Part of the material in the second diversion flows upward along the channel formed between the diversion plate (31) and the guide plate (32), and another part flows upward through the guide hole (33). The diversion plate (31) and the guide plate (32) evenly distribute the incoming material to one end of each heat exchange tube (7).

4. A distributed tube reactor according to claim 3, characterized in that: The diversion plate (31) is fixed to the inner wall of the material inlet end cap (2) by a number of support frames (34), and the guide plate (32) is fixed to the diversion plate (31) by support frames (34). The diversion plate (31) adopts a funnel-shaped structure with an arc similar to that of the material inlet end cap (2).

5. A distributed tube reactor according to claim 4, characterized in that: The heat exchange tubes (7) are arranged in an equilateral triangle pattern.

6. A distributed tube reactor according to claim 5, characterized in that: The diameter of the heat exchange tube (7) in the central region (13) is 0.8:1 compared to the diameter of the heat exchange tube (7) in the outer region.

7. A distributed tube reactor according to claim 6, characterized in that: The guide plate (32) is located below the heat exchange tube (7) in the central region (13), and the diameter of the guide hole (33) is 0.5 to 0.6 times the diameter of the heat exchange tube (7).

8. A distributed tube reactor according to claim 1, characterized in that: The tube reactor body (6) includes a reactor shell (61), an upper tube sheet (65) and a lower tube sheet (66) located at the upper and lower ends of the reactor shell (61), a plurality of spaced tubes (63), baffles (62) and tie rods (64) located inside the reactor shell (61), a tube reactor heat medium inlet (8) and a tube reactor heat medium outlet (11) located on the side of the reactor shell (61), and the two ends of the heat exchange tube (7) are respectively located between the lower tube sheet (66) and the upper tube sheet (65).

9. A distributed tube reactor according to claim 8, characterized in that: An anti-impact plate (9) is provided at the heat medium inlet (8) of the tubular reactor.

Images