Distributed tubular reactor

Abstract

The invention discloses a distributed tubular reactor which comprises a tubular reactor body, a material inlet end seal head and a plurality of heat exchange tubes arranged in the tubular reactor body and used for conveying materials in the material inlet end seal head upwards, and a material guide device is arranged in the material inlet end seal head. Materials entering the material inlet end socket are distributed through the material guiding device and then evenly distributed to the heat exchange pipe ends. The problem that the material collapses when entering the liquid level of the prepolymerization reaction kettle can be solved, so that the stability of the whole polycondensation reaction process and the index of a produced product is ensured.

Description

Technical Field

[0001] The present invention relates to the field of reactors, and particularly to a distributed tube reactor. Background Art

[0002] Polyester (PET), also known as terylene, is a synthetic fiber with extremely wide applications. Its application fields cover textiles, clothing, automotive accessories, industrial products, protective clothing, etc., and it plays a very important role in national economy and people's livelihood. At present, industrial production mainly uses purified terephthalic acid and ethylene glycol to prepare polyester melt through esterification, prepolymerization, and final polymerization reactions, and then forms polyester filament or staple fiber through a series of physical treatment processes such as booster pumps, melt coolers, spinning boxes, ring blowing (side blowing), oiling, winding, etc. At present, the mainstream polyester devices of melt direct spinning enterprises in the chemical fiber industry can be divided into: the four-kettle / five-kettle process device of the China National Textile and Apparel Council, the three-kettle process device of Conti, and the three-kettle process device of Polyunion. Compared with the four-kettle / five-kettle process device of the China National Textile and Apparel Council, the Conti and Polyunion three-kettle process devices are characterized by short reaction time, plug flow of material flow, fewer dynamic equipment used in the material transmission process, more energy-saving, and due to the high efficiency of their reactors, the prepared finished products have strong differentiation, excellent performance, and flexible style, and are deeply favored by the market and consumers.

[0003] In the prepolymerization reaction stage of the Conti and Polyunion three-kettle process devices, the reaction kettle is mainly composed of a tube reactor at the lower part and a tray-type reaction kettle at the upper part. The esterified product (BHET) and additives (catalyst, titanium dioxide, trimonomer, diethylene glycol, etc.) generated in the esterification stage are sent into the lower head of the tube reactor by a gear pump. The material flows through the tube side, and the heat transfer oil flows through the shell side, and a large amount of heat exchange occurs therein to heat the material to above 280 degrees within a short time, and then enters the up-flow tray prepolymerization kettle in a vacuum state from the upper part of the tube reactor. Under the combined action of high temperature, additives and vacuum, intense pre-condensation reactions occur between the esterified products, and ethylene glycol small molecules are removed to form a prepolymer with a polymerization degree of about 12-20, creating a condensation condition for further reaction in the final polymerization. It can be seen that the tube reactor plays a crucial role in the prepolymerization stage.

[0004] In the actual production of the Conti and Juyou three-kettle process units, the liquid level in the prepolymerization kettle often drops abnormally suddenly, accompanied by drastic fluctuations in the temperature of the material at the outlet of the prepolymerization heater. This phenomenon is known as material collapse in the industry. As is well known, in a continuous polyester production unit, the liquid level and temperature are very important parameters, which are the key factors determining the stability of product indicators. The occurrence of the material collapse phenomenon will lead to abnormal prepolymerization reactions, significant changes in the degree of polymerization, and large fluctuations in the prepolymer viscosity. The feeding from prepolymerization to final polymerization is unstable, ultimately resulting in changes in the entire polycondensation reaction process and fluctuations in the material viscosity. In severe cases, it will even lead to changes in product indicators and production accidents of product downgrading, becoming a long-standing problem plaguing the industry.

[0005] In response to this phenomenon, our R & D personnel and production technology team analyzed from various reasons related to the material collapse phenomenon. After years of production practice for demonstration and using the method of eliminating one by one, it was finally determined that it was caused by the unreasonable design of the current shell-and-tube reactor: when the material enters the head from the straight pipe of the pipeline, due to the short distance of the head and short residence time, the dispersion is limited. Coupled with the unreasonable arrangement design of the internal tubes in the reactor and the relatively small length / diameter ratio design of the shell-and-tube reactor, most of the materials with high pressure preferentially enter the tubes arranged in the center facing each other, and very little or no material is distributed to the tubes near the periphery. Especially when the production capacity of the unit is relatively low, this distribution situation is more common. Such a situation leads to the underutilization of the heat transfer area of the shell-and-tube reactor, poor thermal efficiency, and a higher heat medium temperature is required to reach the reaction temperature. During normal production, especially in the production of cationic polyester units, as the production cycle extends, the fluidity of the material in the central tubes (mainly due to the formation of material deposits on the inner wall of the central tubes at high temperatures) changes, the resistance increases, and gradually accumulates to a certain extent. The materials concentrated in the central tubes suddenly disperse and fill the empty tubes or tubes with less material in the periphery in a short time. Since the flow rate of the esterified product entering the shell-and-tube reactor is constant, this leads to an instant decrease in the amount of material entering the prepolymerization reactor, and the liquid level drops suddenly (material collapse). Under the condition of a fixed heat medium temperature, when the empty tubes are filled with materials, the heat transfer area suddenly increases, and the material temperature rises instantaneously. Due to its suddenness and unpredictability, it causes disorder in the prepolymerization reaction, adjustment lag, and a long recovery time, ultimately resulting in serious product downgrading accidents. After the material pressure is released, as time goes by, in a large-scale continuous polyester unit, the material collapse phenomenon may even occur repeatedly, bringing greater economic losses to the enterprise. Summary of the Invention

[0006] To solve certain technical problems existing in the prior art, the purpose of this application is to provide a distributed tube reactor, which can solve the problem that the liquid level in the prepolymerization reactor often collapses, thus ensuring the stability of the entire polycondensation reaction process and the production product indicators.

[0007] To solve the above-mentioned existing technical problems, the purpose of this application is achieved by adopting the following technical solutions: A distributed tube reactor includes a tube reactor body, a material inlet end head, and a plurality of heat exchange tubes arranged in the tube reactor body for conveying the material in the material inlet end head upward. A material guiding device is arranged in the material inlet end head, and the material entering the material inlet end head is evenly distributed to the ends of each heat exchange tube after being shunted by the material guiding device.

[0008] Preferably, the material inlet of the material inlet end head adopts a stepped expanding pipe structure that gradually becomes larger from bottom to top.

[0009] In the present invention, the material inlet at the bottom of the material inlet end head is changed from a straight pipe to a stepped expanding pipe, so as to facilitate the dispersion and release of the material pressure in the pipeline before entering the material inlet end head, reduce the material flow rate, and thus achieve the preliminary diffusion and distribution of the material, reduce the impact pressure, and effectively solve the problem that the dispersion is limited due to the short distance and short residence time of the material inlet end head after the material enters the material inlet end head from the straight pipe of the existing pipeline.

[0010] Preferably, the material guiding device includes a shunt plate and a guide plate. The guide plate is provided with guide holes. After the material entering from the material inlet end head is shunted by the shunt plate, a part of the material is drained along the annular channel formed between the shunt plate and the inner wall of the material inlet end head to one end of the outer heat exchange tubes, and another part of the material flows upward through the hole in the middle of the shunt plate and is shunted again by the guide plate. A part of the material in the re-shunted material flows upward along the channel formed between the shunt plate and the guide plate, and another part of the material flows upward through the guide holes. The shunt plate and the guide plate evenly distribute the entering material to one end of each heat exchange tube.

[0011] Preferably, the shunt plate is fixed to the inner wall of the material inlet end head by a plurality of support frames, the guide plate is fixed to the shunt plate by a support frame, and the shunt plate adopts a funnel-shaped structure that is close to the internal radian of the material inlet end head.

[0012] The material guiding device is composed of a shunt plate, a support frame, and a guide plate with diversion holes. Among them, the shunt plate adopts a funnel-shaped structure that is close to the inner arc of the head at the material inlet end. The shunt plate is fixed on the inner wall of the head heat medium jacket in the head at the material inlet end by the support frame. After the material enters the inside of the head at the material inlet end, the shunt plate can make the material flow more smoothly to the lower ends of the heat exchange tubes at the periphery, thus avoiding the problem of collapse caused by insufficient material supply in the outer heat exchange tubes after being transported to the prepolymerization kettle. The guide plate with diversion holes is located in the middle of the opening end of the shunt plate, forming a certain distance from the feed hole in the middle of the shunt plate through the support frame. After the straight-through material enters the shunt plate, it can be secondarily divided by the shunt plate, so that a part of the material can be directly transported to the lower ends of the heat exchange tubes in the middle area through the diversion holes, while the other part of the material can flow along the channel between the shunt plate and the guide plate to the lower ends of the heat exchange tubes between the middle area and the outer area, thus achieving the purpose of evenly distributing the material entering the head at the material inlet end to the lower ends of each heat exchange tube in different areas after guiding, and avoiding the problem that when the material is transported through the heat exchange tubes, there is an excess in the middle and less supply near the periphery due to the straight-through of the material, and avoiding the occurrence of collapse phenomenon. Especially when the funnel-shaped shunt plate is combined with the bottom material inlet of the head at the material inlet end with a stepped expansion pipe structure, the material pressure in the pipeline can be dispersed and released before entering the head at the material inlet end, and then rapid shunting can be achieved, reducing the impact pressure entering the shunt plate, and making the material flow more evenly and gently along the heat exchange tubes.

[0013] Preferably, there is one head heat medium inlet and two head heat medium outlets on the head at the material inlet end. The head heat medium inlet is arranged on the lower side of the head at the material inlet end, and there are two head heat medium outlets arranged on both upper sides of the head at the material inlet end. A heat medium double-outlet insulation system outer jacket layer is formed inside the side wall of the head at the material inlet end through the head heat medium inlet and the head heat medium outlets.

[0014] The head heat medium outlet of the head at the material inlet end is designed from a single circuit to a double circuit, making the heat distribution of the head at the material inlet end more uniform and the fluidity of the material better.

[0015] Preferably, the heat exchange tubes are arranged in an equilateral triangle distribution.

[0016] The arrangement of the heat exchange tubes is designed from the traditional diamond distribution to an equilateral triangle distribution; it has the advantages of optimizing the internal fluid distribution and heat transfer in the reactor, thereby being able to improve the reaction effect and reduce energy consumption.

[0017] Preferably, on the premise of not reducing the heat exchange area, the area ratio of the heat exchange tubes in the central area is 20%, and the diameter ratio of the heat exchange tubes in the central area to the heat exchange tubes in the outer area is 0.8:1.

[0018] After reducing the diameter of the heat exchange tubes in the central area, the amount of material entering the central area can be restricted, which is convenient for diversion. Especially when the area of the heat exchange tubes in the central area accounts for 20% and the diameter of the heat exchange tubes in the central area is 0.8 times that of the outer area, the amount of material entering the central area can be effectively restricted. On the premise of not having a great impact on the total heat exchange efficiency of the heat exchanger, the purpose of distributing the material to the surrounding can also be achieved, which is convenient for more stable diversion.

[0019] Preferably, the baffle plate is located below the heat exchange tubes in the central area, and the aperture of the diversion hole is 0.5 - 0.6 times the diameter of the heat exchange tubes.

[0020] Preferably, the shell-and-tube reactor body includes a reactor shell, upper and lower tube sheets provided at the upper and lower ends of the reactor shell, a number of spacer tubes, baffle plates and tie rods provided in the reactor shell, a shell-and-tube reactor heat medium inlet and a shell-and-tube reactor heat medium outlet provided on the side of the reactor shell, and both ends of the heat exchange tubes are respectively provided between the lower tube sheet and the upper tube sheet.

[0021] Both ends of the heat exchange tubes penetrate through the lower tube sheet and the upper tube sheet and are fixed by the lower tube sheet and the upper tube sheet. Sealing treatment is carried out between both ends of the heat exchange tubes and the lower tube sheet and the upper tube sheet, so that the material flows from bottom to top along the inside of the heat exchange tubes, and after the heat medium enters the reactor shell, it flows along the outer wall of the heat exchange tubes. Among them, a number of baffle plates in the shell-and-tube reactor body are fixed at equal intervals in the reactor shell by using spacer tubes and tie rods. The upper end of the material inlet end head is connected to the lower tube sheet by studs and sealed by using a spiral wound gasket; heat insulation rings are provided on the outer sides of the reactor shell and the material inlet end head, and the upper tube sheet is connected to the lower flange surface of the prepolymerization kettle by studs.

[0022] Preferably, the ratio of the length L to the diameter d of the reactor shell is 2.686.

[0023] By increasing the ratio of the length L to the diameter d of the shell-and-tube reactor, without changing the heat exchange area, it is increased from the original 2.31 to 2.686, and the structural shape is changed from "short and fat" to "thin and long", which is more conducive to the uniform distribution of materials.

[0024] Preferably, an impact plate is provided at the shell-and-tube reactor heat medium inlet.

[0025] By designing an impact plate at the shell-and-tube reactor heat medium inlet, after the heat medium enters from the shell-and-tube reactor heat medium inlet, the impact of the high-pressure heat-conducting oil on the tubes can be alleviated.

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows: During the transportation of materials in the prepolymerization reaction stage, after adding a material guiding device inside the material inlet head, the materials entering the material inlet head can be evenly distributed to the ends of each heat exchange tube in the shell-and-tube reactor through the material guiding device for diversion, so that the materials in the material inlet head can be evenly transported by the heat exchange tubes in each area to the tray-type reactor at the upper part of the reaction kettle. This can solve the problem that in the existing reactor, due to the unreasonable arrangement design of the tubes, most of the materials with high pressure preferentially enter the heat exchange tubes arranged in the center, and there is little or no material distributed to the heat exchange tubes near the periphery. Especially when the production capacity of the device is relatively low, the uneven distribution can also be avoided, so that the heat exchange area of the shell-and-tube reactor can be fully utilized, with high thermal efficiency and stable heat medium temperature supply.

[0027] Especially when producing cationic products, it can effectively avoid the problem that the fluidity of the materials in the heat exchange tubes in the central area changes due to increased resistance, avoid the problem that the liquid level suddenly drops due to different feeding pressures of the materials entering the prepolymerization reactor, and also avoid the problem that the material temperature fluctuates too much instantaneously under the condition of a fixed heat medium temperature, ensuring the stability of the entire polycondensation reaction process and the product indexes. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a schematic diagram of the internal structure of the present invention; Figure 2 is a distribution plan view of the heat exchange tubes in the present invention; In the figure: 1. Head heat medium inlet; 2. Material inlet head; 3. Material guiding device; 31. Shunt plate; 32. Deflector; 33. Diversion hole; 34. Support frame; 4. Head heat medium outlet; 5. Winding gasket; 6. Shell-and-tube reactor body; 61. Reactor shell; 62. Baffle plate; 63. Spacer tube; 64. Tie rod; 65. Upper tube sheet; 66. Lower tube sheet; 7. Heat exchange tube; 71. Heat exchange tubes in other areas; 72. Heat exchange tubes in the central area; 8. Shell-and-tube reactor heat medium inlet; 9. Impact plate; 10. Insulation ring; 11. Shell-and-tube reactor heat medium outlet; 12. Material inlet; 13. Central area. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0029] Next, in combination with the drawings and specific embodiments, the present application will be further described. It should be noted that, on the premise of no conflict, the following-described embodiments or technical features can be arbitrarily combined with each other to form new embodiments.

[0030] In the description of the present application, it should be understood that the orientation or positional relationship indicated by terms such as "upper", "lower", "left", "right", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present application.

[0031] The terms "first", "second", etc. in the present application are used to distinguish similar objects, rather than to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances, so that the embodiments of the present application can be implemented in an order other than those illustrated or described herein, and the objects distinguished by "first", "second", etc. are generally of the same type, and do not limit the number of objects. For example, the first object can be one or more. In addition, "and / or" in the specification and claims means at least one of the connected objects, and the character " / ", generally represents an "or" relationship between the associated objects before and after.

[0032] Example 1: Due to the design defects in the lower tube reactor of the polyester device of melt direct spinning enterprises in the current chemical fiber industry, the liquid level of the prepolymerization kettle often drops abnormally suddenly, accompanied by a drastic fluctuation in the temperature of the material at the outlet of the prepolymerization heater, thus forming a problem called the collapse phenomenon in the industry. The structure of the tube reactor was redesigned. The improved distributed tube reactor is generally composed of a tube reactor body 6 and a material inlet end head 2. As Figure 1As shown in the figure, the shell-and-tube reactor body 6 is composed of a cylindrical reactor shell 61, upper and lower tube sheets 65 and 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 multi-piece parallel baffle plates 62 installed inside the reactor shell 61. The several baffle plates 62 in the shell-and-tube reactor body 6 are fixed at equal intervals in the reactor shell 61 by using spacer pipes 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 upward along the inside of the heat exchange tubes 7. On the side of the reactor shell 61, there are a shell-and-tube reactor hot medium inlet 8 and a shell-and-tube reactor hot medium outlet 11. The hot medium flows into the reactor shell 61 from the shell-and-tube reactor hot medium inlet 8 at the upper end on the side of the reactor shell 61, surrounds the heat exchange tubes 7, and then flows out from the shell-and-tube reactor hot medium outlet 11, thus realizing heat exchange. When the material enters the material inlet end head 2, it is in a state of straight upward impact. This will inevitably cause the impact pressure on the heat exchange tubes in the middle area to be large after the incoming material impacts straight upward. The material preferentially flows upward through the heat exchange tubes in the middle area, and the upward pressure of the material closer to the periphery is smaller. The remaining material will preferentially enter the heat exchange tubes 7 with a large pressure, and finally flow into the heat exchange tubes 7 on the periphery. In this case, it will cause the pressure of the material entering the tray reactor through the heat exchange tubes in the middle area to be greater than that in the peripheral area, resulting in a phenomenon of material collapse due to the difference in flow pressure when entering the tray reactor; especially when the production capacity of the device is relatively low, the situation of uneven material distribution will occur, which will make the heat exchange efficiency of the shell-and-tube reactor unstable, resulting in low thermal efficiency and unstable supply temperature of the hot medium. Therefore, a material guiding device 3 is added in the material inlet end head 2. Through the material guiding device 3, the material that directly enters the material inlet end head 2 can be shunted and evenly distributed to the ends of each heat exchange tube 7 in the shell-and-tube reactor, so that the material in the material inlet end head 2 can be evenly transported by the heat exchange tubes 7 in each area to the tray reactor at the upper part of the reactor, and it can solve the problem that most of the materials with high pressure preferentially enter the heat exchange tubes 7 arranged in the center and facing each other due to the unreasonable arrangement design of the tubes in the existing reactor, and there is very little or no material distributed to the heat exchange tubes 7 near the periphery. Especially when the production capacity of the device is relatively low, the situation of uneven distribution can also be avoided, so that the heat exchange area of the shell-and-tube reactor can be fully utilized, the thermal efficiency is high, and the supply temperature of the hot medium is stable. Especially when producing cationic products, it can effectively avoid the problem that the fluidity of the material in the heat exchange tubes 72 in the central area changes due to the increase in resistance, avoid the problem that the liquid level suddenly drops due to the different feeding pressures of the material entering the prepolymerization reactor, and also avoid the problem that the material temperature fluctuates too much instantaneously under the condition of a fixed hot medium temperature, ensuring the stability of the entire polycondensation reaction process and the production product indicators.

[0033] Further improvement is made as follows: the baffle plate 62 is fixed in the reactor shell 61 through a combination of a plurality of fixed-distance pipes and tie rods 64, so that the baffle plates 62 are arranged in a staggered and parallel manner. After the heat transfer medium flows in from the heat transfer medium inlet 8 of the tubular reactor, it is limited and guided by a plurality of baffle plates 62 and then flows slowly downward, making the heat transfer medium stay longer above each baffle plate 62, with higher heat exchange efficiency, and avoiding the problem that the heat transfer temperature is reduced due to the fact that the cooled heat transfer medium stays in the reactor shell 61 for too long after quickly filling the whole reactor shell 61. The upper tube sheet 65 and the lower flange surface of the prepolymerization kettle are connected by studs. The upper end of the material inlet end head 2 and the lower tube sheet 66 are connected by studs and sealed with a spiral wound gasket 5, and the connection method is simpler; heat insulation rings 10 are provided on the outer sides of the reactor shell 61 and the material inlet end head 2, which can ensure higher heat exchange efficiency of the heat transfer medium, avoid too high temperature in the production environment, and also avoid scalding the staff by the outer shell of the tubular reactor.

[0034] Further improved, the main body of the material guiding device 3 is composed of a shunt plate 31 and a guiding plate 32 with guiding holes 33. Among them, the shunt plate 31 adopts a funnel-shaped structure close to the inner arc of the material inlet end head 2. There is a certain distance between the top of the shunt plate 31 and the lower tube sheet 66. The guiding plate 32 with guiding holes 33 is generally flush with the upper end opening of the shunt plate 31. The shunt plate 31 is suspended and fixed in the material inlet end head 2 by 3-4 support frames 34, and the guiding plate 32 is suspended and fixed in the shunt plate 31 by 3-4 support frames 34. Thus, after the material enters from the material inlet end head 2, a part of the material is shunted through the lower end of the shunt plate 31, so that a part of the material that rushes straight up continues to rush straight up and then enters the shunt plate 31. Another part of the material can be shunted through the shunt plate 31 and then diverted along the annular channel space formed between the shunt plate 31 and the inner wall of the material inlet end head 2 to one end of the heat exchange tubes 7 in a certain range of the outer circle, thereby avoiding the problem that there is not enough material for the heat exchange tubes 7 in the outer circle during material transportation. For the material that rushes straight into the shunt plate 31, a part of the outer periphery flows upward along the inner wall of the shunt plate 31, and a part of the middle part rushes straight up and continues to flow upward. After a part of the straight-rushing material impacts the guiding plate 32, a part is directly transported to the heat exchange tube 7 openings in the middle area through the guiding holes 33, and a part is blocked by the guiding plate 32, fills the inside of the shunt plate 31, and then continues to flow upward along the channel formed between the guiding plate 32 and the shunt plate 31, thereby providing targeted feeding for the heat exchange tubes 7 between the middle area and the outer area. When the straight-rushing material feeds the heat exchange tubes 7, the material can be reasonably distributed to the lower ends of the heat exchange tubes 7 in different areas, avoiding the problem that there is too much pressure in the middle when the material enters the heat exchange tubes 7, and the material supply is insufficient in the outer area due to insufficient pressure, thereby avoiding the abnormal sudden drop of the prepolymerization kettle liquid level in the prepolymerization kettle caused by insufficient material feeding of the heat exchange tubes 7 in the outer circle during upward transportation, and also avoiding the problem of low heat exchange efficiency due to uneven heat exchange.

[0035] Example 2: Due to the unreasonable design of the shell-and-tube reactor, after the material enters the material inlet end head 2 from the straight pipe of the pipeline, due to the short distance and short residence time of the material inlet end head 2, the dispersion is limited, resulting in difficulty in transporting the material to the lower ends of the heat exchange tubes 7 in the outer circle in the first time. Even if the material guiding device 3 is added, it is impossible to flow along the inner wall of the material inlet end head 2 to the outermost heat exchange tubes 7 in time after the material enters the material inlet end head 2. Therefore, to solve this problem, the material inlet 12 of the material inlet end head 2 adopts a stepped expansion pipe structure that gradually increases from bottom to top.

[0036] Thus, in the present invention, the material inlet 12 at the bottom of the material inlet end head 2 is changed from a straight pipe to a stepped expansion pipe. When the material enters, it can be drained through the stepped expansion pipe, causing part of the material to directly impact and flow through the channel formed by the inner wall of the material inlet end head 2 and the flow dividing plate 31, so that the material under pressure flows towards the outer heat exchange tubes 7, which helps to disperse and release the pressure of the material in the pipeline before entering the material inlet end head 2, reduce the flow rate of the material, and thus achieve the preliminary diffusion and distribution of the material, reduce the impact pressure, and effectively solve the problem that the dispersion is limited due to the short distance and short residence time of the material inlet end head 2 when the material enters the material inlet end head 2 from the straight pipe of the existing pipeline. Among them, the lower opening of the flow dividing plate 31 extends arcuately into the material inlet 12, and the diameter of the lower port of the flow dividing plate 31 is smaller than the inner diameter of the material inlet 12. When the funnel-shaped flow dividing plate 31 is combined with the material inlet 12 at the bottom of the material inlet end head 2 with a stepped expansion pipe structure, it can disperse and release the pressure of the material in the pipeline before entering the material inlet end head 2 and then achieve rapid flow division, reduce the impact pressure entering the flow dividing plate 31, increase the pressure of the material flowing along the outside of the flow dividing plate 31, and make the material more evenly and gently transported under pressure along the heat exchange tubes 7 in different regions.

[0037] Embodiment 3: Since there is only one head hot medium inlet 1 and one head hot medium outlet 4 in the existing material inlet end head 2, the flow of the hot medium in the interlayer is restricted, resulting in sufficient heating in some areas where the hot medium flows along the direction of the head hot medium inlet 1 and the head hot medium outlet 4, while there is a problem of relatively lower temperature in the areas with low hot medium replacement efficiency, leading to uneven heating, and the side with lower temperature is prone to cause a problem of reduced fluidity of the material. Therefore, the flow path of the hot medium is redesigned. One head hot medium inlet 1 and two head hot medium outlets 4 are provided on the material inlet end head 2. The head hot medium inlet 1 is provided on the lower side surface of the material inlet end head 2, and two head hot medium outlets 4 are provided on both upper sides of the material inlet end head 2. An outer jacket layer of a heat medium double-outlet insulation system is formed in the side wall of the material inlet end head 2 through the head hot medium inlet 1 and the head hot medium outlets 4.

[0038] Through the design of the head hot medium inlet 1 and the two head hot medium outlets 4, the flow of the hot medium is changed from a single loop design to a double loop design. By symmetrically designing one head hot medium outlet 4 on both sides, more uniform and rapid replacement of the hot medium in the interlayer can be achieved, avoiding the problem of reduced heating temperature caused by untimely replacement of some hot medium, making the heat distribution of the material inlet end head 2 more uniform and the fluidity of the material better.

[0039] Example 4: In existing shell-and-tube reactors, the ratio of length L to diameter d is generally 2.31, and the heat exchange tubes 7 are arranged in a diamond pattern, with each heat exchange tube 7 having the same diameter. Most of the materials with high pressure will preferentially enter the heat exchange tubes 7 arranged in the center of the front row, resulting in very little or no material distributed to the heat exchange tubes 7 near the periphery. Even after the improvements in Examples 1 to 3, it is difficult to avoid the problem that the flow rate of materials flowing through the heat exchange tubes 7 in the middle is slightly greater than that of the materials in the periphery. Especially when the production capacity of the device is relatively low, this distribution situation is more common. Such a situation leads to the underutilization of the heat exchange area of the shell-and-tube reactor, and it is difficult to achieve the best thermal efficiency. The heat exchange tubes 7 are arranged in an equilateral triangle pattern instead of the traditional diamond pattern; as Figure 2 shown, it has the advantages of optimizing the internal fluid distribution and heat transfer in the reactor, thereby improving the reaction effect and reducing energy consumption. At the same time, without reducing the heat exchange area, by reducing the diameter of the heat exchange tubes 72 in the central area, the amount of materials entering the central area 13 can be restricted, facilitating the diversion. Especially when the area of the heat exchange tubes 72 in the central area accounts for about 20%, and the diameter of the heat exchange tubes 72 in the central area is about 0.8 times the diameter of the heat exchange tubes 71 in other areas, the amount of materials entering the central area 13 can be effectively restricted, making the materials transported into the prepolymerization kettle more uniform whether in the middle or the periphery, and it is not easy to have the situation where the material supply in the middle is significantly greater than that in the periphery. Without significantly affecting the overall heat exchange efficiency of the heat exchanger, the purpose of material distribution to the surroundings can also be achieved, facilitating more stable diversion. At the same time, the flow guide plate 32 is located below the heat exchange tubes 72 in the central area. If the aperture of the flow guide hole 33 is too large, it is easy to cause the direct impact of the material on the heat exchange tubes 7, resulting in the problem that a certain heat exchange tube 7 is subjected to excessive impact pressure from the material. Therefore, when designing the aperture of the flow guide hole 33, its diameter is set to be 0.5 to 0.6 times the diameter of the heat exchange tubes 7, so that even if the flow guide hole 33 is directly opposite the lower port of the heat exchange tubes 7, it can ensure that a 100% impact feeding situation does not occur, effectively stabilizing the material pressure in the heat exchange tubes 7.

[0040] Furthermore, it is further improved that the ratio of the length L to the diameter d of the reactor shell 61 is 2.686; increasing the ratio of the length L to the diameter d of the shell-and-tube reactor, without changing the heat exchange area, from the original 2.31 to 2.686, the structural shape changes from "short and fat" to "thin and long", which is more conducive to the uniform distribution of materials. A shock-proof plate 9 is provided at the heat medium inlet 8 of the shell-and-tube reactor, so that after the heat medium enters from the heat medium inlet 8 of the shell-and-tube reactor, it can relieve the impact of the high-pressure heat-conducting oil on the tubes, ensuring that the heat exchange efficiency of the heat medium in the entire reactor shell 61 is more stable and avoiding the occurrence of local overheating. The shock-proof plate 9 can adopt a honeycomb plate structure and is generally fixed at a certain distance interval from the heat medium inlet 8 of the shell-and-tube reactor through a bracket.

[0041] After the above improvements, it can effectively solve the problem that the liquid level and temperature, two parameters of the existing tubular reactor, are uncontrollably fluctuating due to unreasonable design, stabilize the degree of polymerization during the production process of the product, and ensure the stability of the pre-polymerization viscosity and the feeding from pre-polymerization to final polymerization, thus ensuring the stability of the product indicators of the produced products and preventing production accidents such as product downgrading.

[0042] The above embodiments are only the preferred embodiments of the present application and cannot be used to limit the scope of protection of the present application. Any non-substantive changes and substitutions made by those skilled in the art based on the present application belong to the scope of protection required by the present application.

Claims

1. A distributed tube reactor, comprising a tube reactor body (6), a material inlet end head (2), and a plurality of heat exchange tubes (7) disposed in the tube reactor body (6) for conveying the material in the material inlet end head (2) upward, characterized in that: A material guiding device (3) is provided inside the material inlet end head (2). The material entering the material inlet end head (2) is shunted by the material guiding device (3) and then evenly distributed to the ends of each heat exchange tube (7).

2. The distributed tube reactor according to claim 1, wherein: The material inlet (12) of the material inlet end head (2) adopts a reducing expansion pipe structure that gradually increases from bottom to top.

3. A distributed tubular reactor according to claim 2, characterized in that: The material guiding device (3) includes a shunt plate (31) and a guide plate (32). The guide plate (32) is provided with guide holes (33). After the material entering from the material inlet end head (2) is shunted by the shunt plate (31), a part of the material is drained along the annular channel formed between the shunt plate (31) and the inner wall of the material inlet end head (2) to one end of the outer heat exchange tubes (7), and the other part flows upward through the hole in the middle of the shunt plate (31) and is shunted again by the guide plate (32). Among the materials shunted again, a part of the material flows upward along the channel formed between the shunt plate (31) and the guide plate (32), and the other part flows upward through the guide holes (33). The shunt plate (31) and the guide plate (32) evenly distribute the entering material to one end of each heat exchange tube (7).

4. A distributed tube reactor according to claim 3, characterized in that: The shunt plate (31) is fixed to the inner wall of the material inlet end head (2) through a plurality of support frames (34). The guide plate (32) is fixed to the shunt plate (31) through the support frames (34). The shunt plate (31) adopts a funnel-shaped structure that is close to the internal radian of the material inlet end head (2).

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

6. A distributed tube reactor according to claim 5, wherein: On the premise of not reducing the heat exchange area, the area ratio of the heat exchange tubes (7) in the central area (13) is 20%, and the diameter ratio of the heat exchange tubes (7) in the central area (13) to the heat exchange tubes (7) in the external area is 0.8:

1.

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

8. A distributed tube reactor according to claim 1, characterized in that: One heat medium inlet (1) and two heat medium outlets (4) are provided on the material inlet end head (2). The heat medium inlet (1) is arranged on the lower side surface of the material inlet end head (2), and there are two heat medium outlets (4) which are arranged on both upper sides of the material inlet end head (2). A heat medium double-outlet heat preservation system outer jacket layer is formed inside the side wall of the material inlet end head (2) through the heat medium inlet (1) and the heat medium outlets (4).

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

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

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