Heat exchanger, reactor and application thereof, and olefin polymerization method

Abstract

The invention provides a heat exchanger, a reactor and application thereof and an olefin polymerization method.The heat exchanger comprises a shell pass barrel, a heat exchange tube arranged in the shell pass barrel, a first tube plate arranged at the first end of the shell pass barrel and a first end plate connected to the outer side of the first tube plate, and the first end plate is provided with an input through hole and an output through hole; the surface, facing the first tube plate, of the first end plate is provided with a partition located between the input through hole and the output through hole, the partition divides the portion, between the first tube plate and the first end plate, of the first end plate into an input cavity and an output cavity which are communicated with the heat exchange tube, and the through-flow area of the input through hole is larger than that of the output through hole. According to the technical scheme, the space between the first end plate and the first tube plate is divided by the partition piece to form the input cavity and the output cavity, the through-flow area of the output through hole is smaller than that of the input through hole, fluid obtained after heat exchange can flow out at a higher flow speed, and therefore blockage in the output through hole is avoided or reduced.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of Chinese patent application 202311316249.9 filed on October 11, 2023, the contents of which are incorporated herein by reference. Technical Field

[0003] The invention relates to the field of heat exchange, in particular to a heat exchanger, a reactor and application thereof, and an olefin polymerization method. Background Art

[0004] Polyethylene is a product with a relatively high output among polymer materials, and my country's polyethylene production capacity cannot meet actual demand. Different polyethylene varieties usually use different production processes. HDPE and LLDPE are both produced using low-pressure polyethylene processes, and the polymerization pressure is usually less than 6MPa; while LDPE is produced using high-pressure polyethylene processes, and the polymerization pressure is usually higher than 200MPa. The polyethylene produced by the slurry polyethylene process is in a slurry state because it is insoluble in solvents.

[0005] In order to control the production temperature in the polyethylene production process, it is necessary to remove the heat generated in the process in a timely manner. The existing method is usually to add a slurry heat exchanger or a gas phase heat exchanger outside the reactor. When using a slurry heat exchanger, the reaction materials are cooled by the slurry heat exchanger and returned to the polymerization reactor. The heat exchanger is filled with a circulating coolant.

[0006] In the prior art, a shell and tube heat exchanger includes a shell and internal heat exchange tubes and tube sheets, and a tube box is formed between the tube sheet and the spherical heads at both ends. The fluid first enters the tube box and then passes through the heat exchange tubes, and finally is discharged through the tube box at the other end. CN113188352A discloses a high-efficiency compact heat exchanger and a heat exchange amount calculation method. The purpose of the invention is to make the heat exchanger have the advantages of compact structure and high heat exchange efficiency, and to make the heat exchange amount calculation method have the advantages of concise calculation process, simple formula form, strong versatility and high calculation accuracy. CN205580262U discloses a wave point against viscous fluid tube heat exchanger, which adds wave flow plates in the heat exchange tube to achieve disturbance of the viscous fluid. However, when the shell and tube heat exchanger of the prior art is used for slurry heat exchange, its operation cycle is relatively short, and it needs to be shut down for maintenance regularly, which affects the production efficiency. Summary of the invention

[0007] One of the purposes of the present invention is to overcome the problem of short operating cycle of the heat exchanger in the prior art when used for slurry heat exchange.

[0008] In order to achieve the above-mentioned purpose, the present invention provides a heat exchanger on the one hand, wherein the heat exchanger includes a shell-side cylinder, a heat exchange tube arranged in the shell-side cylinder, a first tube sheet arranged at the first end of the shell-side cylinder, and a first end plate connected to the outer side of the first tube sheet, the first end plate is provided with an input through hole and an output through hole, and the surface of the first end plate facing the first tube sheet is provided with a partition located between the input through hole and the output through hole, the partition separates the first tube sheet and the first end plate to form an input cavity and an output cavity connected to the heat exchange tube, and the flow area of ​​the input through hole is larger than the flow area of ​​the output through hole.

[0009] In some embodiments, in the direction from the first end plate to the first tube plate, the thickness of the partition gradually decreases, and two sides of the partition respectively form a first slope surface extending to the edge of the input through hole and a second slope surface extending to the edge of the output through hole, and the first slope surface and the second slope surface extend to the first tube plate.

[0010] In some embodiments, a first recessed portion is provided on a surface of the first end plate facing the first tube plate, the partition is provided in the first recessed portion, and the first recessed portion is formed with a third slope surface extending to an edge of the input through hole and a fourth slope surface extending to an edge of the output through hole.

[0011] In some embodiments, the first slope surface and the third slope surface transition smoothly to form a smooth gradually diverging wall surface defining the input cavity; the second slope surface and the fourth slope surface transition smoothly to form a smooth gradually converging wall surface defining the output cavity.

[0012] In some embodiments, an input tube connected to the input through hole and an output tube connected to the output through hole are disposed on a side of the first end plate facing away from the first tube plate.

[0013] In some embodiments, a first drain pipe connected to the shell-side cylinder is disposed on the first tube sheet.

[0014] In some embodiments, the heat exchanger includes a second tube sheet connected to the second end of the shell cylinder and a second end plate connected to the outside of the second tube sheet, and a return cavity connected to the heat exchange tube is formed between the second end plate and the second tube sheet, and the volume of the return cavity gradually decreases from the center to the edge.

[0015] In some embodiments, a second recessed portion is disposed on a surface of the second end plate facing the second tube plate, and a cross-sectional area of ​​the second recessed portion gradually decreases in a direction away from the second tube plate.

[0016] In some embodiments, the second recessed portion is conical, a first connecting tube and a second connecting tube are arranged on the outer periphery of both ends of the shell-side cylinder, avoidance areas adjacent to the first connecting tube and the second connecting tube are arranged in the shell-side cylinder, the heat exchange tube is not arranged in the avoidance area, and a sealing block axially aligned with the avoidance area is arranged in the second recessed portion.

[0017] In some embodiments, the blocking block is integrally formed on the second end plate; and / or the second recessed portion is provided with two blocking blocks symmetrically arranged about the central axis of the shell-side cylinder.

[0018] In some embodiments, an exhaust pipe communicating with the return cavity is disposed on a side of the second end plate facing away from the second tube plate.

[0019] In some embodiments, a second drain pipe connected to the shell-side cylinder is disposed on the second tube sheet.

[0020] In some embodiments, the arrangement density of the heat exchange tubes is arranged from dense to sparse in the direction from the center of the shell cylinder toward the edge. It should be noted that the inventor of this solution first discovered that when the heat exchanger is used for slurry heat exchange, the peripheral heat exchange tubes are more easily blocked or blocked more seriously than the central heat exchange tubes. Therefore, the distribution density of the heat exchange tubes in the periphery is designed to be smaller than the distribution density of the heat exchange tubes in the central area to ensure that the slurry fluid medium in the peripheral heat exchange tubes has sufficient flow and flow velocity, avoiding or reducing the blockage of the slurry fluid medium in the peripheral heat exchange tubes.

[0021] In some embodiments, a plurality of baffles are disposed inside the shell-side cylinder.

[0022] On the other hand, the present scheme provides a reactor, wherein the reactor includes a main shell and the heat exchanger described in the above scheme, the main shell is provided with a first opening located at the upper part and a second opening located at the lower part, a circulation pipeline is provided between the first opening and the second opening, and the heat exchanger is provided on the circulation pipeline.

[0023] In some embodiments, a cooling jacket is provided on at least a portion of the wall of the main shell.

[0024] In some embodiments, the reactor also includes a gas phase outlet arranged at the top of the main shell and a gas phase inlet arranged at the lower part of the main shell, and a cooler and a gas-liquid separator are connected in sequence between the gas phase outlet and the gas phase inlet, the gas phase outlet is connected to the inlet of the material to be cooled of the cooler, and the gas phase inlet is connected to the gas phase logistics outlet of the gas-liquid separator.

[0025] In some embodiments, the reactor includes a discharge pipeline connected to the bottom of the main shell and a sampling assembly bypassing the discharge pipeline, the sampling assembly includes a sampling pipeline, a liquid feeding pipeline, a filter container, and a collection container, the two ends of the sampling pipeline are respectively connected to the discharge pipeline and the top inlet of the filter container, and the two ends of the liquid feeding pipeline are respectively connected to the bottom outlet of the filter container and the top inlet of the collection container.

[0026] In some embodiments, a control valve is provided on the discharge pipeline, and the sampling pipeline is connected to the control valve.

[0027] In some embodiments, the sampling assembly includes a test line, one end of which is connected to a compressed air source, and the other end of which is connected to the sampling line.

[0028] In some embodiments, the sampling assembly includes a pre-cleaning pipeline, one end of which is connected to a cleaning solvent container, and the other end of which is connected to the sampling pipeline.

[0029] In some embodiments, the sampling assembly includes a jacket, a heating pipeline and a condensate pipeline arranged outside the filter container, a filter bag is arranged in the filter container, one end of the heating pipeline is connected to the steam pipeline network and the other end is connected to the upper part of the jacket, one end of the condensate pipeline is connected to the lower part of the jacket and the other end is connected to the steam condensate pipeline network.

[0030] In some embodiments, the sampling assembly includes an exhaust line connected to a top outlet of the collection container and a drain line connected to a bottom outlet of the collection container.

[0031] In some embodiments, the sampling assembly includes a heater disposed on the filtration container.

[0032] In some embodiments, the main housing is configured as an autoclave.

[0033] In another aspect, the reactor is used in a slurry reaction, preferably, the slurry reaction is olefin slurry polymerization.

[0034] On the other hand, the present scheme provides an olefin polymerization method, which adopts the reactor described above, including contacting at least one olefin with an olefin polymerization catalyst and a diluent in the main shell of the reactor under slurry polymerization conditions, characterized in that the method also includes drawing out a part of the slurry polymerization product from the main shell of the reactor as a first slurry product, exchanging heat between the first slurry product and a cooling medium in a heat exchanger to obtain a first slurry product after heat exchange, the temperature of the first slurry product after heat exchange is lower than the temperature of the first slurry product, and drawing the first slurry product after heat exchange back into the main shell.

[0035] In some embodiments, the diluent is a C4-C6 alkane, preferably hexane and / or pentane.

[0036] In some embodiments, the temperature of the cooling medium is higher than 40°C, preferably higher than 40°C and not higher than 65°C;

[0037] Preferably, the temperature of the cooling medium at the inlet of the heat exchanger is higher than 40°C and not higher than 55°C;

[0038] Preferably, the residence time of the first slurry product in the heat exchanger is 1-30s;

[0039] Preferably, the temperature of the first slurry product after the heat exchange is 72-85°C.

[0040] In some embodiments, the method further includes introducing a second cooling medium into the cooling jacket to exchange heat with the material inside the main shell.

[0041] In some embodiments, the method further includes drawing out at least a portion of the vapor phase from the main shell through a vapor phase outlet, cooling the vapor phase in a cooler, performing gas-liquid separation on the cooled vapor phase in a gas-liquid separator to obtain a liquid phase and a vapor phase, and introducing at least a portion of the gas phase back into the main shell through a vapor phase inlet.

[0042] Through the above technical scheme, the first end plate and the first tube plate are separated by a partition to form an input cavity and an output cavity. The flow area of ​​the output through-hole is smaller than the flow area of ​​the input through-hole, which can allow the fluid after heat exchange to flow out at a larger flow rate, thereby avoiding or reducing blockage in the output through-hole; slopes are formed on both sides of the partition to directional guide the medium, reasonably allocate the flow space, and reduce the residence time of the medium in the tube box, thereby effectively inhibiting the wax aggregation phenomenon in the heat exchanger; the input cavity and the output cavity are formed into a gradual structure, which can adapt to the characteristics of the smaller distribution density of the heat exchange tubes in the edge part, so that the fluid flows quickly in the edge part of the input cavity and the output cavity, ensuring that the fluid in the heat exchange tube corresponding to the outer edge part has a sufficiently high flow rate, ensuring that the overall flow rate of the fluid medium is stable, and further avoiding or reducing the wax aggregation phenomenon. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the embodiments of the present disclosure or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0044] Figure 1is a schematic structural diagram of a first end of a heat exchanger according to an embodiment of the present invention;

[0045] Figure 2 is a schematic structural diagram of the first end plate described in the implementation mode of this scheme;

[0046] Figure 3 is a cross-sectional view of the first end plate described in the implementation mode of this scheme;

[0047] Figure 4 is a schematic structural diagram of the second end of the heat exchanger described in the implementation scheme of this solution;

[0048] Figure 5 is a schematic structural diagram of the second end plate described in the implementation scheme of this solution;

[0049] Figure 6 is a cross-sectional view of the second end plate described in the implementation mode of this scheme;

[0050] Figure 7 It is a schematic diagram of the structure of the reactor described in the implementation mode of this scheme;

[0051] Figure 8 It is a schematic diagram of the sampling assembly described in the implementation mode of this scheme.

[0052] Description of Reference Numerals

[0053] 100-heat exchanger, 110-shell cylinder, 111-first pipe joint, 112-second pipe joint, 113-baffle, 120-first tube sheet, 121-first liquid discharge pipe, 130-second tube sheet, 131-second liquid discharge pipe, 140-first end plate, 141-input through hole, 142-output through hole, 143-partitioning member, 144-first recessed portion, 145-input pipe, 146-output pipe, 147-input cavity, 148-output cavity, 150-second end plate, 151-return cavity, 152-second recessed portion, 153-exhaust pipe, 154-sealing block, 160-heat exchange pipe, 200-main shell, 201-circulation pipeline, 202-discharge pipeline, 300-sampling assembly, 301-filter container, 302-collection container, 303-sampling pipeline, 304-test pipeline, 305-pre-cleaning pipeline, 306-liquid delivery pipeline, 307-heating pipeline, 308-condensate pipeline, 309-exhaust pipeline, 310-discharge pipeline, 1431-first slope, 1432-second slope, 1441-third slope, 1442-fourth slope. DETAILED DESCRIPTION

[0054] The specific implementation of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the present invention, and is not used to limit the present invention.

[0055] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0056] refer to Figure 1-Figure 6 As shown, the present scheme provides a heat exchanger, wherein the heat exchanger 100 includes a shell-side cylinder 110, a heat exchange tube 160 arranged in the shell-side cylinder 110, a first tube sheet 120 arranged at the first end of the shell-side cylinder 110, and a first end plate 140 connected to the outer side of the first tube sheet 120, the first end plate 140 is provided with an input through hole 141 and an output through hole 142, and the surface of the first end plate 140 facing the first tube sheet 120 is provided with a partition 143 located between the input through hole 141 and the output through hole 142, the partition 143 separates the first tube sheet 120 and the first end plate 140 to form an input cavity 147 and an output cavity 148 connected to the heat exchange tube 160, and the flow area of ​​the input through hole 141 is larger than the flow area of ​​the output through hole 142.

[0057] The heat exchanger is a shell and tube heat exchanger, wherein the shell side cylinder 110 is the main structure, and its cross section can be circular or square, etc., wherein a heat exchange tube 160 is arranged, and the space between the heat exchange tube 160 and the shell side cylinder 110 is the shell side, and the internal space of the heat exchange tube 160 is the tube side.

[0058] At the first end of the heat exchanger, the shell-side cylinder 110 is provided with a first tube sheet 120 and a first end plate 140. The first tube sheet 120 is provided with holes for accommodating the insertion of the heat exchange tube 160 or docking with the heat exchange tube 160 to support the heat exchange tube 160. The edge portions of the surfaces facing each other of the first end plate 140 and the first tube sheet 120 are fitted together to form a seal.

[0059] At least one of the surfaces of the first end plate 140 and the first tube plate 120 facing each other is recessed, so that a cavity for accommodating fluid is formed between the first tube plate 120 and the first end plate 140. The partition 143 divides the cavity into two cavities, namely, an input cavity 147 and an output cavity 148. The input cavity 147 is connected to the input through hole 141 and a part of the heat exchange tube 160, and the output cavity 148 is connected to the output through hole 142 and another part of the heat exchange tube 160. The fluid passes through the input through hole 141, the input cavity 147, and the heat exchange tube 160 in sequence to reach the other end of the heat exchanger, and then returns (for example, through the return cavity described below) to the heat exchange tube 160, and is discharged through the output cavity 148 and the output through hole 142 in sequence. The partition 143 is used to separate the input cavity 147 and the output cavity 148, and it can be a part of the first end plate 140 or a part of the first tube plate 120. Of course, it can also be independent of the first end plate 140 and the tube plate 120 and only be located between the two.

[0060] It can be seen that the first end plate 140 replaces the head having a flat plate-shaped partition in the prior art.

[0061] The flow area of ​​the input through hole 141 is larger than the flow area of ​​the output through hole 142, allowing the flow rate of the input fluid to be larger than the flow rate of the output through hole 142, which is suitable for the case where the volume of the fluid decreases after the temperature decreases, such as partial gas liquefaction. In addition, since the flow area of ​​the output through hole 142 is smaller, it is more conducive to the rapid flow of the medium fluid through the output through hole 142 and the connected output pipe 146, avoiding the formation of wax accumulation or even blockage in the output through hole 142 and the connected output pipe 146.

[0062] The separator 143 is dam-shaped and is preferably arranged in the middle position of the first end plate 140. In the direction from the first end plate 140 to the first tube sheet 120, the thickness of the separator 143 gradually decreases. The two sides of the separator 143 respectively form a first slope 1431 extending to the edge of the input through hole 141 and a second slope 1432 extending to the edge of the output through hole 142. The first slope 1431 and the second slope 1432 extend to the first tube sheet 120.

[0063] The return cavity at the other end of the shell-side cylinder 110 may be formed by a spherical head in the prior art, or by the structure described below in the present solution.

[0064] The first end plate and the first tube plate are separated by a partition to form an input cavity and an output cavity. Slopes are formed on both sides of the partition, which eliminate the medium static area and the turbulent area, and can guide the fluid to flow quickly along the slope. When used for slurry heat exchange, the medium flow can be smoother, so that the fluid medium can flow through the tube box (i.e., the input cavity and the output cavity) more quickly, avoiding wax accumulation or even blockage in the tube box, effectively ensuring the heat exchange effect, and extending the continuous operation cycle of the equipment.

[0065] In the shell and tube heat exchanger in the prior art, wax accumulation and even blockage are prone to occur in the tube box part, so its operating cycle is short and it needs to be shut down for maintenance and cleaning. The present solution optimizes the end plate structure and optimizes the structure of the input cavity 147 and the output cavity 148, so that the fluid can pass through quickly, shortening the flow time and avoiding or reducing wax accumulation and even blockage.

[0066] In addition, the first end plate 140 is made of stainless steel, and its thickness can be set to be smaller, and a pressure plate made of carbon steel is set on its outer side. The pressure plate and the first end plate 140 are connected to the first tube plate 120 by bolts or other connection methods, which can improve the overall strength and reduce material costs.

[0067] Among them, reference Figure 2 As shown, the partition 143 is generally formed on the first end plate 140 and can be located at one of the diameters of the first end plate 140, such as Figure 3 As shown, the thickness of the partition 143 gradually decreases, so that a first slope 1431 extending to the edge of the input through hole 141 and a second slope 1432 extending to the edge of the output through hole 142 are formed on both sides, which makes the axial size of the input cavity 147 or the output cavity 148 aligned with the heat exchange tube 160 in the middle part of the first tube sheet 120 relatively smaller, and compared with a plate structure with uniform thickness (whose thickness corresponds to the thickness at the minimum thickness of the partition 143), the volume of the input cavity 147 and the output cavity 148 is reduced. In addition, the first slope 1431 forms a guide surface between the first tube sheet 120 and the input through hole 141. , so that the fluid flows along the first slope 1431 from the input through hole 141 directly to the first tube sheet 120 to enter the heat exchange tube 160, and the second slope 1432 forms a guiding surface between the first tube sheet 120 and the output through hole 142, so that the fluid flows along the second slope 1432 from the first tube sheet 120 to the output through hole 142. The two guiding surfaces can further eliminate the medium static area and the turbulent area, guide the flow of the medium fluid, make the medium flow smoother, help reduce pressure drop, reduce material aggregation and blockage, ensure that the fluid passes through the input cavity, the output cavity and the heat exchange tube 160 more smoothly, and avoid or reduce wax aggregation or even blockage.

[0068] Among them, reference Figure 2As shown, the surface of the first end plate 140 facing the first tube plate 120 is provided with a first recessed portion 144, the separator 143 is provided in the first recessed portion 144, and the first recessed portion 144 is formed with a third slope 1441 extending to the edge of the input through hole 141 and a fourth slope 1442 extending to the edge of the output through hole 142. In other embodiments, a recessed portion may also be provided on the tube plate. In this solution, the first tube plate 120 adopts a conventional tube plate structure, and the first end plate 140 replacing the conventional spherical head is generally a flat plate, on which the first recessed portion 144 is provided and separated by the separator 143 to form two recessed portions, thereby cooperating with the first tube plate 120 to form an input cavity 147 and an output cavity 148. Among them, the thickness of the first end plate 140 is 160-170 mm, and the depth of the first recessed portion 144 is approximately 70-80 mm. Figure 2 In the figure, the first recessed portion 144 is provided with two third slopes 1441 located on both sides of the first slope 1431 around the input through hole 141, and the two third slopes 1441 form a guide surface between the input through hole 141 and the first tube sheet 120. Similar to the first slope 1431, the third slope 1441 can guide the flow of fluid and reduce the flow dead angle; the first recessed portion 144 is provided with two fourth slopes 1442 located on both sides of the second slope 1432 around the output through hole 142, and the two fourth slopes 1442 form a guide surface between the output through hole 142 and the first tube sheet 120. Similar to the second slope 1432, the fourth slope 1442 can guide the flow of fluid and reduce the flow dead angle.

[0069] Furthermore, the first slope 1431 and the third slope 1441 are smoothly transitioned to form a smooth gradually expanding wall defining the input cavity 147; the second slope 1432 and the fourth slope 1442 are smoothly transitioned to form a smooth gradually contracting wall defining the output cavity 148. Figure 2, the end of the first recessed portion 144 facing the first tube sheet 120 is a circular interface, the partition 143 divides it into two semicircular interfaces, and the ends of the input cavity 147 and the output cavity 148 facing the first tube sheet 120 are semicircular interfaces. Among them, the first slope 1431 and the third slope 1441 are smoothly transitioned, so that a smooth transition is formed between the input through hole 141 and the semicircular interface, guiding the fluid to flow from the input channel 141 to the first tube sheet 120 more quickly; the second slope 1432 and the fourth slope 1442 are smoothly transitioned, so that a smooth transition is formed between the output through hole 142 and the semicircular interface, guiding the fluid to flow from the first tube sheet 120 to the output through hole 142 more quickly. The input cavity 147 and the output cavity 148 are cavities with a semicircular interface at one end and a smaller circular interface at the other end. The semicircular interface and the circular interface are transitioned by a special-shaped smooth transition surface to form a tapered structure, which can reduce the flow dead angle, reduce the cavity volume, and allow the fluid to pass more quickly, thereby increasing the flow speed. In other words, the input cavity 147 and the output cavity 148 are formed into a special-shaped funnel or trumpet shape. It should be noted that the special-shaped smooth transition surfaces in the input cavity 147 and the output cavity 148 are difficult to process. Therefore, a square flat bottom surface can be set at the bottom of the cavity, and an input through hole 141 or an output through hole 142 can be set on the flat bottom surface. The corresponding slope surface described above is set around the flat bottom surface, and no smooth transition can be formed between adjacent slope surfaces.

[0070] When the input cavity 147 is formed into a gradually expanding type, the axial dimension of the edge portion is smaller, so the volume of the edge portion of the input cavity 147 is smaller. It should be noted that the inventor of this scheme first discovered that when the heat exchanger is used for slurry heat exchange, the peripheral heat exchange tube is more easily blocked or blocked more seriously than the central heat exchange tube. A portion of the edge of the input cavity 147 corresponds to the edge portion of the shell cylinder 110, that is, corresponds to the heat exchange tube 160 of the peripheral portion. Therefore, the smaller edge portion of the input cavity 147 adapts to the smaller flow of the heat exchange tube 160 of the peripheral edge portion of the shell cylinder 110. By reducing the volume of the edge portion of the input cavity 147, the flow rate of the fluid medium in its edge portion is guaranteed, so that the medium fluid can flow quickly in the heat exchange tube 160 of the peripheral edge portion, ensuring the overall flow rate of the medium fluid and avoiding wax aggregation or even blockage. The output cavity 148 has a similar mechanism and will not be described in detail here.

[0071] In addition, an input pipe 145 connected to the input through hole 141 and an output pipe 146 connected to the output through hole 142 are provided on the side of the first end plate 140 facing away from the first tube plate 120. The free ends of the pipe 145 and the output pipe 146 may be provided with flanges for connection with other pipe fittings.

[0072] Among them, the ratio of the flow area of ​​the input through hole 141 to the flow area of ​​the output through hole 142 is 18:10-15, for example, 18:10, 18:10.5, 18:11, 18:11.5, 18:12, 18:12.5, 18:13, 18:13.5, 18:14, 18:14.5, 18:15, etc.

[0073] In addition, refer to Figure 3 As shown, the free end of the partition 143 (ie, the end facing the first tube sheet 120 ) includes a portion with a constant thickness, which can be inserted into the first tube sheet 120 to form a good seal.

[0074] In addition, the first tube sheet 120 is provided with a first drain pipe 121 connected to the shell side cylinder 110. The first drain pipe 121 is connected to the shell side and can be used to discharge the fluid therein. During normal use, it is in a disconnected state.

[0075] In addition, the heat exchanger includes a second tube sheet 130 connected to the second end of the shell-side cylinder 110 and a second end plate 150 connected to the outer side of the second tube sheet 130, and a return cavity 151 connected to the heat exchange tube 160 is formed between the second end plate 150 and the second tube sheet 130, and the volume of the return cavity 151 gradually decreases from the center to the edge. At least one of the surfaces of the second tube sheet 130 and the second end plate 150 facing each other forms a recessed portion to form the return cavity 151 therebetween. The first part of the heat exchange tube 160 connected to the input cavity 147 inputs the fluid into the return cavity 151, and then inputs it into the second part of the heat exchange tube 160 to return to the output cavity 148. It should be noted that the inventor of the present invention discovered for the first time that when the heat exchanger is used for slurry heat exchange, the peripheral heat exchange tubes are more likely to be blocked or blocked more seriously than the central heat exchange tubes. The edge portion of the return cavity 151 has a smaller volume, so that the fluid can flow quickly through the edge portion of the return cavity 151 (to quickly leave or enter the peripheral heat exchange tubes 160), thereby allowing the fluid medium in the peripheral edge portion of the heat exchange tubes 160 to have sufficient flow rate and flow velocity, thereby avoiding blockage in the peripheral heat exchange tubes 160.

[0076] Specifically, refer to Figure 5As shown, the surface of the second end plate 150 facing the second tube sheet 130 is provided with a second recessed portion 152, and the cross-sectional area of ​​the second recessed portion 152 gradually decreases in the direction away from the second tube sheet 130. The number of heat exchange tubes 160 arranged at the center of the second tube sheet 130 is greater, and the number of heat exchange tubes 160 at the edge is less. Therefore, the axial dimension of the edge of the second recessed portion 152 is smaller than the axial dimension of the center, and the space is relatively smaller, that is, the center of the return cavity 151 has a larger space, and the edge has a smaller space, so as to adapt to the flow distribution of the fluid at different positions, and ensure that the fluid has basically the same flow and flow velocity in the peripheral heat exchange tube 160 and the central heat exchange tube 160, thereby avoiding or alleviating the problem of easy blockage in the peripheral heat exchange tube 160. Among them, the maximum depth of the second recessed portion 152 is 12-15mm. Among them, the second recessed portion 152 is conical or truncated cone shaped.

[0077] The second recessed portion 152 is conical, and the first connecting tube 111 and the second connecting tube 112 are arranged on the outer periphery of both ends of the shell-side cylinder 110. The shell-side cylinder 110 is provided with avoidance areas adjacent to the first connecting tube 111 and the second connecting tube 112, respectively, and the heat exchange tube 160 is not arranged in the avoidance area. The second recessed portion 152 is provided with a blocking block 154 axially aligned with the avoidance area. For ease of explanation, the second recessed portion 152 is set to be conical. In fact, after the blocking block 154 is set, the second recessed portion 152 is only approximately conical, which is equivalent to cutting off two parts of the cone at the edge. The blocking block 154 is arched in the cross section perpendicular to the axial direction of the shell-side cylinder 110, such as Figure 5 shown.

[0078] The first connecting tube 111 and the second connecting tube 112 are both connected to the inside of the shell cylinder 110, that is, connected to the shell, and can be used to input and output heat exchange fluids. Flanges can be set at their free ends to facilitate connection with other pipes. Among them, near the connection between the first connecting tube 111 and the second connecting tube 112, no heat exchange tube 160 is set on the tube sheet to form an avoidance area, that is, no heat exchange tube 160 is set to avoid the fluid that is about to flow into or out of the first connecting tube 111 and the second connecting tube 112, so as to ensure the medium flow space at the shell inlet and outlet positions. The area where the heat exchange tube 160 is not set on the second tube sheet 130 is arched, so the blocking block 154 set in the second recessed portion 152 is aligned with the arched area of ​​the second tube sheet 130 where the heat exchange tube 160 is not set, so as to occupy the area on the second tube sheet 130 where the heat exchange tube is not set, and avoid the formation of a medium static area and a turbulent area here.

[0079] The blocking block 154 is integrally formed on the second end plate 150; and / or, the second recessed portion 152 is provided with two blocking blocks 154 symmetrically arranged about the central axis of the shell-side cylinder 110. Since the second recessed portion 152 does not extend to the arcuate area occupied by the blocking block 154, it forms an approximate cone shape, which is equivalent to a cone shape with the arcuate portion cut off. In other words, a conical recessed area with the arcuate portion cut off is machined in the second end plate 150 to form the second recessed portion 152. The introduction of the blocking block 154 structure is to more clearly describe the irregular shape of the second recessed portion 152, such as Figure 5 In addition, the first connecting pipe 111 and the second connecting pipe 112 are located at both ends of the shell cylinder 110, and the circumferential angle between the two positions is 180 degrees, for example, they are respectively located on the upper side and the lower side of the horizontally extended shell cylinder 110, and accordingly, the circumferential angle of the two blocking blocks 154 is also 180 degrees, that is, symmetrical about the central axis, ensuring the symmetry of the second recessed portion 152, so that the distribution of the fluid is also symmetrical; of course, the first connecting pipe 111 and the second connecting pipe 112 can also be set to be axially aligned, and the circumferential angle of the two blocking blocks 154 is still 180 degrees, which is also to ensure the symmetry of the second recessed portion 152, so that the distribution of the fluid is symmetrical.

[0080] The side of the second end plate 150 facing away from the second tube plate 130 is provided with an exhaust pipe 153 connected to the return cavity 151. The exhaust pipe 153 can discharge gas or liquid in the return cavity, and it remains disconnected in normal use and can be opened during maintenance.

[0081] In addition, the second tube sheet 130 is provided with a second row of clean pipes 131 connected to the shell-side cylinder 110. The second row of clean pipes 131 has a similar function to the first row of clean pipes 121, and will not be described again.

[0082] The arrangement density of the heat exchange tubes 160 is arranged from dense to sparse in the direction from the center of the shell-side cylinder 110 toward the edge. For example, the shell-side cylinder 110 may be a circular cylinder, in which the density of the heat exchange tubes 160 at the center is higher and the density at the edge is lower. It should be noted that the inventor of the present solution discovered for the first time that when the heat exchanger is used for slurry heat exchange, the peripheral heat exchange tubes are more easily blocked or blocked more seriously than the central heat exchange tubes. Therefore, the distribution density of the heat exchange tubes in the periphery is designed to be smaller than the distribution density of the heat exchange tubes in the central area to ensure that the slurry fluid medium in the peripheral heat exchange tubes has sufficient flow rate and flow velocity, thereby avoiding or reducing the blockage of the slurry fluid medium in the peripheral heat exchange tubes.

[0083] This solution is specifically designed to address the problem of easy or more serious blockage in the peripheral heat exchange tubes. On the one hand, it reduces the volume of the edge portions of the input cavity 147, the output cavity 148, and the return cavity 151, so that the fluid can quickly flow through and enter the peripheral heat exchange tubes. On the other hand, it makes the distribution density of the peripheral heat exchange tubes smaller than the distribution density of the heat exchange tubes in the central area. The two aspects are combined to ensure the flow rate and flow velocity of the medium fluid in the peripheral heat exchange tubes, thereby avoiding or reducing the blockage problem.

[0084] Wherein, a plurality of baffles 113 are arranged inside the shell-side cylinder 110. Figure 1 and Figure 4 As shown, the baffles 113 are alternately arranged on both sides of the shell-side cylinder 110 to form a tortuous channel, so that the fluid forms a deflection therein, extending the flow path of the fluid to more fully exchange heat with the heat exchange tubes 160.

[0085] On the other hand, reference Figure 7 As shown, the present scheme provides a reactor, wherein the reactor includes a main shell 200 and the heat exchanger 100 described in the above scheme, the main shell 200 is provided with a first opening located at the upper part and a second opening located at the lower part, a circulation pipeline 201 is provided between the first opening and the second opening, and the heat exchanger 100 is arranged on the circulation pipeline 201.

[0086] The main shell 200 can be used as a carrier for the reaction, and the circulation pipeline 201 can export the material therein and remove heat through the heat exchanger 100, and then introduce the cooled material into the main shell 200 to achieve heat removal of the internal environment.

[0087] In addition, refer to Figure 8 As shown, the reactor includes a discharge pipeline 202 connected to the bottom of the main housing 200 and a sampling assembly 300 connected to the discharge pipeline 202. The sampling assembly 300 includes a sampling pipeline 303, a liquid delivery pipeline 306, a filter container 301, and a collection container 302. The two ends of the sampling pipeline 303 are respectively connected to the discharge pipeline 202 and the top inlet of the filter container 301, and the two ends of the liquid delivery pipeline 306 are respectively connected to the bottom outlet of the filter container 301 and the top inlet of the collection container 302. The discharge pipeline 202 can discharge the reaction product in the main housing 200; the sampling assembly 300 is used to take out part of the material in the discharge pipeline 202 to perform sampling operations, so as to facilitate the detection of reaction products.

[0088] Among them, the sampling pipeline 303 is connected to the discharge pipeline 202 to extract part of the reaction product and transport it to the filter container 301. The filter container 301 can filter the reaction product to achieve solid-liquid separation; the collection container 302 is connected to the filter container 301 and can collect the separated solution.

[0089] In addition, a control valve is provided on the discharge pipeline 202, and the sampling pipeline 303 is connected to the control valve. A control valve, such as a plunger valve, is provided on the discharge pipeline 202 to control the connection and disconnection of the sampling pipeline 303. When disconnected, the reaction product in the discharge pipeline 202 will not enter the sampling pipeline 303, thereby preventing the reaction product from being retained in the sampling pipeline 303. In other embodiments, a three-way valve may also be provided on the discharge pipeline 202, and its main purpose is also to prevent the material from entering the sampling pipeline 303 when no sampling operation is performed.

[0090] In addition, refer to Figure 8 As shown, the sampling assembly 300 includes a test pipeline 304, one end of which is connected to a compressed gas source, and the other end is connected to the sampling pipeline 303. Before the sampling operation is performed, when the sampling pipeline 303 is disconnected from the discharge pipeline 202, compressed gas (such as nitrogen, etc.) can be passed to each pipeline, the filter container 301, and the collection container 302 through the test pipeline 304 to check the air tightness of the pipeline.

[0091] In addition, the sampling assembly 300 includes a pre-cleaning pipeline 305, one end of which is connected to a cleaning solvent container, and the other end is connected to the sampling pipeline 303. The cleaning solvent can be introduced into the sampling pipeline 303 through the pre-cleaning pipeline 305, and the residual reaction product can be cleaned to avoid affecting the sampling detection. The pre-cleaning operation can be performed before the sampling operation to ensure the accuracy of the sampling detection.

[0092] In addition, the sampling assembly 300 includes a jacket, a heating pipeline 307 and a condensate pipeline 308 arranged outside the filter container 301. A filter bag is arranged in the filter container 301. One end of the heating pipeline 307 is connected to the steam network and the other end is connected to the upper part of the jacket. One end of the condensate pipeline 308 is connected to the lower part of the jacket and the other end is connected to the steam condensate network. The filter bag is used to filter the reaction product to achieve solid-liquid separation; steam can be introduced into the jacket through the heating pipeline 307 to heat the filter container 301, so that the liquid remaining on the filter container 301 after filtering evaporates, so as to discharge the hydrocarbons in the sampling system and safely open the filter; the steam in the jacket condenses to form condensate, and the condensate returns to the steam condensate network through the condensate pipeline 308. In other embodiments, an electric heater can also be used to heat the filter container 301.

[0093] In addition, reference Figure 8 As shown, the sampling assembly 300 includes an exhaust pipeline 309 connected to the top outlet of the collection container 302 and a drain pipeline 310 connected to the bottom outlet of the collection container 302. The exhaust pipeline 309 can exhaust the gas replaced by nitrogen (for example, introduced by the test pipeline 304 during testing) to avoid residual hydrocarbon gas inside. When a large amount of solution is stored in the collection container 302, the drain pipeline 310 at the bottom can be opened to discharge the solution.

[0094] The present solution also provides the use of the above-mentioned reactor in a slurry reaction. Preferably, the slurry reaction is olefin slurry polymerization.

[0095] On the other hand, the present scheme provides an olefin polymerization method, which adopts the reactor described above, including contacting at least one olefin with an olefin polymerization catalyst and a diluent in the main shell of the reactor under slurry polymerization conditions, wherein the method also includes drawing out a part of the slurry polymerization product from the main shell of the reactor as a first slurry product, exchanging heat with a cooling medium in a heat exchanger to obtain a first slurry product after heat exchange, the temperature of the first slurry product after heat exchange is lower than the temperature of the first slurry product, and drawing the first slurry product after heat exchange back into the main shell.

[0096] In one embodiment, the diluent is a C4-C6 alkane, preferably hexane and / or pentane, the hexane is n-hexane, and the pentane is n-pentane.

[0097] In a particularly preferred embodiment, the diluent is n-pentane. The inventors have found through research that in the slurry polymerization process of polyethylene, when n-pentane is used as a diluent, the reaction conditions are mild and the solvent recovery process can be carried out at significantly lower energy consumption, thereby making the solution of this solution suitable for industrial large-scale production. The low solubility of n-pentane solvent for oligomers is conducive to establishing a new balance between the mechanical properties and processing properties of high-density polyethylene.

[0098] In a preferred embodiment, the temperature of the cooling medium is higher than 40°C, preferably higher than 40°C and not higher than 65°C. This preferred embodiment can effectively inhibit the wax in the polymer slurry from precipitating and accumulating on the wall of the heat exchanger. In this preferred embodiment, the temperature of the cooling medium at the inlet of the heat exchanger is higher than 40°C and not higher than 55°C. In this preferred embodiment, the residence time of the first slurry product in the heat exchanger can be 1-30s. The temperature of the cooling medium can be 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65°C, preferably 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55°C.

[0099] In a preferred embodiment, the temperature of the first slurry product after the heat exchange is 72-85°C.

[0100] In a preferred embodiment, a jacket is provided on at least a portion of the wall of the reactor, and the method further comprises introducing a second cooling medium into the cooling jacket to exchange heat with the material inside the main shell.

[0101] In a preferred embodiment, the method further comprises drawing out at least part of the vapor phase from the main shell through the vapor phase outlet, cooling the vapor phase in a cooler, separating the cooled vapor phase into a gas-liquid separator to obtain a liquid phase and a vapor phase, and drawing at least part of the vapor phase back into the main shell through the vapor phase inlet. The inventors have found that in this preferred embodiment, the method of this scheme rarely or never reduces production capacity due to the formation of a film on the wall of the polymerization reactor; and, in this method, ordinary cooling water involved in the aforementioned heat exchanger of the present invention can be used instead of chilled water; and in this preferred case, the heat removal efficiency per unit volume of the polymerization reactor is high, and even all the heat of the polymerization reactor can be removed.

[0102] Preferably, the olefin is ethylene, or a combination of ethylene and at least one monomer selected from 1-hexene, 1-butene and 1-octene.

[0103] According to a preferred embodiment, the olefin is ethylene.

[0104] According to another preferred embodiment, the olefin is a combination of ethylene and at least one monomer selected from 1-hexene and 1-butene.

[0105] Preferably, the olefin polymerization catalyst is one or more selected from Ziegler-Natta catalyst (ZN), metallocene catalyst and non-metal catalyst.

[0106] The present scheme has no special requirements on the introduction form of the olefin polymerization catalyst, which can be supplied in the form of slurry or dry powder. For example, it can be diluted to a certain concentration with a diluent and then added to the polymerization reactor with a metering pump.

[0107] Preferably, the conditions in the polymerization reactor include: a polymerization temperature of 60-90° C. and a polymerization pressure of 0.4-2.8 MPa.

[0108] Preferably, in the polymerization reactor of the scheme, the weight ratio of the olefin to the hydrogen is 800-1500:1.

[0109] Preferably, in the polymerization reactor of the present embodiment, the amount of the catalyst used is 0.01 g to 0.1 g per 1 kg of olefin.

[0110] Preferably, the diluent is used in an amount such that the concentration of the slurry at the bottom of the polymerization reactor is 35-42 wt%, preferably 37-40 wt%.

[0111] The method of the present scheme has no special requirements on the heat exchange area of ​​the heat exchanger and the flow rate of the slurry in the heat exchanger. Those skilled in the art can determine the reasonable heat exchange area of ​​the heat exchanger and the flow rate of the slurry in the heat exchanger according to the designed temperature difference requirements and the temperature of the cooling medium. The specific data values ​​are exemplarily provided in the examples below of the present invention, which should not be construed as limitations on the present invention by those skilled in the art.

[0112] The method of this scheme has no special requirements for the post-processing operation of the slurry polymerization product, and can be carried out in an operation method known in the art. Taking the polymerization process of ethylene as an example, the slurry polymerization product obtained in the method of the present invention can be partially extracted through the slurry external circulation pump, and then the unreacted ethylene monomer and hydrogen can be separated by flash evaporation. The separated slurry can enter the next polymerization kettle system according to the brand or be combined with the slurry of another polymerization kettle system to enter the centrifugal separation system. The flash gas is recovered by condensation compression. The slurry is continuously added to the high-speed rotating horizontal centrifuge through the slurry delivery pump, and separated into polymer wet cake and mother liquor. Part of the mother liquor is recycled, and part is recycled in the solvent recovery unit. The wet cake enters the dryer for drying and then enters the degassing bin for further drying, and then is sent to the blending system through the air delivery system for blending, and then sent to the packaging system.

[0113] The method of the present invention has no special requirements on the ratio of raw materials (such as olefins, olefin polymerization catalysts, diluents, hydrogen, etc.) involved in the polymerization reaction, and can be carried out using parameter conditions known in the art. Several dosage relationships are exemplified as examples in the following text of the present invention, which should not be construed as limitations on the present invention by those skilled in the art.

[0114] The polymerization reactor of the present invention is preferably at least three reactors arranged in parallel.

[0115] The present invention will be described in detail below by way of examples. In the following examples, unless otherwise specified, the raw materials used are all common commercially available products.

[0116] Unless otherwise specified, the following examples and comparative examples all adopt the pentane slurry polyethylene process to produce polyethylene, which involves three reactors connected in parallel (each reactor is provided with a heat exchanger, and the connection between the reactor and the heat exchanger is as follows: Figure 7 The specific process includes:

[0117] Ethylene (the introduction rate of ethylene in each reactor is 60.63 kg / h) and hydrogen (the introduction rate of hydrogen in each reactor is 0.048 g / h) are introduced into the polymerization reactor and dispersed in pentane. At the same time, catalyst is introduced (3.7 g / h of BCE catalyst (purchased from Beijing Aoda Branch of Sinopec Catalyst Co., Ltd.) is introduced into each reactor). The concentration of the slurry at the bottom of the polymerization reactor is 38.8 wt%, and the temperature of the polymerization reactor is controlled in the range of 75-78°C.

[0118] Example 1

[0119] This embodiment applies the present invention Figures 1 to 6 The heat exchanger shown in is carried out, wherein a partition is provided, such as Figure 3 As shown, in the direction from the first end plate to the first tube plate, the thickness of the partition gradually decreases; a first slope extending to the edge of the input through hole and a second slope extending to the edge of the output through hole are formed on both sides of the partition, the first end plate is provided with a first recessed portion, the partition is arranged in the first recessed portion to separate the input cavity and the output cavity, the first recessed portion is formed with a third slope extending to the edge of the input through hole and a fourth slope extending to the edge of the output through hole; wherein the ratio of the flow area of ​​the input through hole to the flow area of ​​the output through hole is 18:10, and the arrangement density of the heat exchange tubes is arranged from dense to sparse in the direction from the center of the shell side cylinder toward the edge; the return cavity formed in the second end plate is conical and is provided with a blocking block (such as Figure 6 shown).

[0120] The conditions of the three polymerization reactors in this embodiment are the same. The conditions of one of the polymerization reactors are listed as follows: the temperature of the cooling medium in the heat exchanger at the heat exchanger inlet is 47°C, the temperature at the outlet is 57.1°C, and the heat exchange area of ​​the heat exchanger is 0.94m 2 The flow rate of the slurry in the heat exchange tube is 5.07m / s; the temperature of the slurry entering the heat exchanger is 85℃, the temperature of the slurry at the outlet of the heat exchanger is 83℃, and the average residence time of the slurry in the heat exchanger is 1.2s.

[0121] The performance indexes of the polyethylene product obtained in this example are distributed in the following ranges: melt index (2.16 kg, 190 ° C) is in the range of 12-17 (determined according to GB / T3682.1-2018, the same below), density is 0.960-0.964 g / cm 3 It can be seen that the product obtained in this embodiment has excellent processability.

[0122] The device scale of this embodiment is a test device of 14,400 t / year, and no wax accumulation occurs during the continuous operation of the device for 48 months.

[0123] Example 2

[0124] The difference between this embodiment and embodiment 1 is that a cylindrical cavity (the same as the maximum inner diameter of the first recessed portion) is formed between the first end plate and the first tube plate, and the cylindrical cavity is divided into an input cavity and an output cavity by using the same partition as in embodiment 1, and a first slope surface extending to the edge of the input through hole and a second slope surface extending to the edge of the output through hole are formed on both sides of the partition.

[0125] The performance indexes of the polyethylene product obtained in this example are distributed in the following ranges: melt index (2.16 kg, 190° C.) is in the range of 12-17, density is in the range of 0.960-0.964 g / cm 3 It can be seen that the product obtained in this embodiment has excellent processability.

[0126] The device scale of this embodiment is a test device of 14,400 t / year, and no wax accumulation phenomenon occurred during the continuous operation of the device for 27 months.

[0127] Example 3

[0128] The difference between this embodiment and embodiment 1 is that the return cavity is cylindrical and no blocking block is provided, and the inner diameter of the return cavity is the same as the maximum inner diameter of the conical return cavity in embodiment 1.

[0129] The performance indexes of the polyethylene product obtained in this example are distributed in the following ranges: melt index (2.16 kg, 190° C.) is in the range of 12-17, density is in the range of 0.960-0.964 g / cm 3 It can be seen that the product obtained in this embodiment has excellent processability.

[0130] The device scale of this embodiment is a test device of 14,400 t / year, and no wax accumulation occurs during the continuous operation of the device for 30 months.

[0131] Example 4

[0132] The differences between this embodiment and embodiment 1 are as follows: (1) a cylindrical cavity (the same as the maximum inner diameter of the first recessed portion) is formed between the first end plate and the first tube plate, and the cylindrical cavity is divided into an input cavity and an output cavity by a partition same as that in embodiment 1, and a first slope extending to the edge of the input through hole and a second slope extending to the edge of the output through hole are formed on both sides of the partition; (2) the return cavity is cylindrical and no blocking block is provided, and the inner diameter of the return cavity is the same as the maximum inner diameter of the conical return cavity in embodiment 1; (3) the arrangement density of the heat exchange tubes is the same in the direction from the center of the shell side cylinder toward the edge; (4) the partition is a partition with uniform thickness, and the thickness of the partition is the smallest thickness among the partitions in the heat exchanger in embodiment 1.

[0133] The performance indexes of the polyethylene product obtained in this example are distributed in the following ranges: melt index (2.16 kg, 190° C.) is in the range of 12-17, density is in the range of 0.960-0.964 g / cm 3 It can be seen that the product obtained in this embodiment has excellent processability.

[0134] The device scale of this embodiment is a test device of 14,400 t / year, and no wax accumulation occurs during the continuous operation of the device for 24 months.

[0135] Example 5

[0136] The difference between this embodiment and embodiment 4 is that the temperature of the cooling medium in the heat exchanger at the inlet and outlet of the heat exchanger is different. In embodiment 5, the temperature of the cooling medium at the inlet of the heat exchanger is 41°C, and the temperature at the outlet is 51°C.

[0137] The performance indexes of the polyethylene product obtained in this example are distributed in the following ranges: melt index (2.16 kg, 190° C.) is in the range of 12-17, density is in the range of 0.960-0.964 g / cm 3 It can be seen that the product obtained in this embodiment has excellent processability.

[0138] The device scale of this embodiment is a test device of 14,400 t / year, and no wax accumulation occurs during the continuous operation of the device for 21 months.

[0139] Comparative Example 1

[0140] The heat exchanger used in Comparative Example 1 is slightly different in structure from the heat exchanger in Example 4, the difference being that the flow area of ​​the input through hole in the heat exchanger of Comparative Example 1 is the same as the flow area of ​​the output through hole.

[0141] The conditions of the three polymerization reactors in Comparative Example 1 are the same, and the conditions of one of the polymerization reactors are listed as follows: the temperature of the cooling medium in the heat exchanger in Comparative Example 1 is 48°C at the inlet of the heat exchanger, the temperature at the outlet is 60°C, and the heat exchange area of ​​the heat exchanger is 0.94m 2 The flow rate of the slurry in the heat exchange tube is 5.07m / s; the temperature of the slurry entering the heat exchanger is 85℃, the temperature of the slurry at the outlet of the heat exchanger is 83℃, and the average residence time of the slurry in the heat exchanger is 1.2s.

[0142] The performance indexes of the polyethylene product obtained in Comparative Example 1 are distributed in the following ranges: melt index (2.16 kg) is in the range of 10-15, density is in the range of 0.956-0.961 g / cm 3 within the range.

[0143] Results: The device scale of comparative example 1 is a test device with an annual capacity of 14,400 t. After 22 months of continuous operation, wax accumulation occurred.

[0144] Moreover, compared with Example 1, material deposition is more likely to occur at the head tube box of the heat exchanger of Comparative Example 1.

[0145] Comparative Example 2

[0146] Comparative Example 2 was carried out using the same heat exchanger as in Comparative Example 1.

[0147] The conditions of the three polymerization reactors in Comparative Example 2 are the same, and the conditions of one of the polymerization reactors are listed as follows: the temperature of the cooling medium in the heat exchanger in Comparative Example 2 is 41°C at the inlet of the heat exchanger, and the temperature at the outlet is 51°C. The heat exchange area of ​​the heat exchanger is 0.94m 2 The flow rate of the slurry in the heat exchange tube is 5.07m / s; the temperature of the slurry entering the heat exchanger is 85℃, the temperature of the slurry at the outlet of the heat exchanger is 83℃, and the average residence time of the slurry in the heat exchanger is 1.2s.

[0148] The performance indexes of the polyethylene product obtained in Comparative Example 2 are distributed in the following ranges: melt index (2.16 kg) is in the range of 10-15, density is in the range of 0.954-0.958 g / cm 3 within the range.

[0149] Results: The device scale of Comparative Example 2 is a test device with an annual capacity of 14,400 t. After 16 months of continuous operation, wax accumulation occurred.

[0150] Moreover, compared with Example 1, material deposition is more likely to occur at the head tube box of the heat exchanger of Comparative Example 2.

[0151] It can be seen from the experimental results of Examples 1-5 and Comparative Examples 1-2 that, when polyethylene is prepared by a device using the heat exchanger of the present invention, the continuous operation period of the device is long while obtaining a product with good processing performance, wherein the heat exchanger structure is optimized so that the medium fluid can be quickly discharged from the output through hole and the output pipe, ensuring that the medium fluid in the heat exchanger has a sufficient flow rate, avoiding or reducing the wax accumulation phenomenon in the heat exchanger, and effectively extending the stability time of the heat exchanger.

[0152] The preferred embodiments of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various specific technical features in any suitable manner. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations. However, these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A heat exchanger, characterized in that: The heat exchanger (100) comprises a shell-side cylinder (110), a heat exchange tube (160) arranged in the shell-side cylinder (110), a first tube sheet (120) arranged at the first end of the shell-side cylinder (110), and a first end plate (140) connected to the outer side of the first tube sheet (120), wherein the first end plate (140) is provided with an input through hole (141) and an output through hole (142), and a partition (143) located between the input through hole (141) and the output through hole (142) is provided on a surface of the first end plate (140) facing the first tube sheet (120), wherein the partition (143) is used to separate an input cavity (147) and an output cavity (148) that are in communication with the heat exchange tube (160) between the first tube sheet (120) and the first end plate (140), wherein a flow area of ​​the input through hole (141) is greater than a flow area of ​​the output through hole (142).

2. The heat exchanger according to claim 1, wherein: In the direction from the first end plate (140) to the first tube plate (120), the thickness of the partition (143) gradually decreases, and two sides of the partition (143) respectively form a first slope surface (1431) extending to the edge of the input through hole (141) and a second slope surface (1432) extending to the edge of the output through hole (142), and the first slope surface (1431) and the second slope surface (1432) extend to the first tube plate (120).

3. The heat exchanger according to claim 2, wherein: A first recessed portion (144) is provided on a surface of the first end plate (140) facing the first tube plate (120), the partition (143) is arranged in the first recessed portion (144), and the first recessed portion (144) is formed with a third slope surface (1441) extending to the edge of the input through hole (141) and a fourth slope surface (1442) extending to the edge of the output through hole (142).

4. The heat exchanger according to claim 3, wherein: The first slope surface (1431) and the third slope surface (1441) transition smoothly to form a smooth gradually expanding wall surface defining the input cavity (147); the second slope surface (1432) and the fourth slope surface (1442) transition smoothly to form a smooth gradually contracting wall surface defining the output cavity (148).

5. A heat exchanger according to any one of the preceding claims, wherein: An input pipe (145) connected to the input through hole (141) and an output pipe (146) connected to the output through hole (142) are provided on a side of the first end plate (140) facing away from the first tube plate (120).

6. A heat exchanger according to any one of the preceding claims, wherein: The first tube sheet (120) is provided with a first row of clean tubes (121) connected to the shell-side cylinder (110).

7. A heat exchanger according to any one of the preceding claims, wherein: The heat exchanger further comprises a second tube sheet (130) connected to the second end of the shell-side cylinder (110) and a second end plate (150) connected to the outer side of the second tube sheet (130); a return cavity (151) connected to the heat exchange tube (160) is formed between the second end plate (150) and the second tube sheet (130); and the volume of the return cavity (151) gradually decreases from the center to the edge.

8. The heat exchanger according to claim 7, wherein: A second recessed portion (152) is provided on the surface of the second end plate (150) facing the second tube plate (130), and the cross-sectional area of ​​the second recessed portion (152) gradually decreases in a direction away from the second tube plate (130).

9. The heat exchanger according to claim 8, wherein: The second recessed portion (152) is conical, and a first connecting tube (111) and a second connecting tube (112) are arranged on the outer periphery of both ends of the shell-side cylinder (110). The shell-side cylinder (110) is provided with avoidance areas respectively adjacent to the first connecting tube (111) and the second connecting tube (112), and the heat exchange tube (160) is not arranged in the avoidance area. The second recessed portion (152) is provided with a sealing block (154) axially aligned with the avoidance area.

10. The heat exchanger according to claim 9, wherein: The blocking block (154) is integrally formed on the second end plate (150); and / or, two blocking blocks (154) are provided in the second recessed portion (152) and are symmetrically arranged about the central axis of the shell-side cylinder (110).

11. The heat exchanger according to claim 7, wherein: An exhaust pipe (153) communicating with the return cavity (151) is provided on a side of the second end plate (150) facing away from the second tube plate (130).

12. The heat exchanger according to claim 7, wherein: The second tube sheet (130) is provided with a second clean pipe (131) connected to the shell-side cylinder (110).

13. A heat exchanger according to any one of the preceding claims, wherein: The arrangement density of the heat exchange tubes is arranged from dense to sparse in the direction from the center of the shell-side cylinder (110) toward the edge.

14. A heat exchanger according to any one of the preceding claims, wherein: A plurality of baffles (113) are arranged inside the shell-side cylinder (110).

15. A reactor, characterized in that: The reactor comprises a main shell (200) and a heat exchanger (100) according to any one of claims 1 to 14, wherein the main shell (200) is provided with a first opening at the top and a second opening at the bottom, a circulation pipeline (201) is provided between the first opening and the second opening, and the heat exchanger (100) is provided on the circulation pipeline (201).

16. The reactor according to claim 15, wherein A cooling jacket is provided on at least part of the wall of the main shell (200).

17. The reactor according to claim 15 or 16, wherein The reactor also includes a gas phase outlet arranged at the top of the main shell (200) and a gas phase inlet arranged at the bottom of the main shell (200), and a cooler and a gas-liquid separator are connected in sequence between the gas phase outlet and the gas phase inlet, the gas phase outlet is connected to the inlet of the material to be cooled of the cooler, and the gas phase inlet is connected to the gas phase flow outlet of the gas-liquid separator.

18. The reactor according to any one of claims 15 to 17, wherein: The main housing (200) is constructed in a kettle type.

19. Use of the reactor according to any one of claims 15 to 18 in a slurry reaction, preferably, the slurry reaction is olefin slurry polymerization.

20. An olefin polymerization method, characterized in that: The method adopts the reactor described in any one of claims 15-18.

21. The method according to claim 20, wherein: The method comprises: contacting at least one olefin with an olefin polymerization catalyst and a diluent in a main shell (200) of a reactor under slurry polymerization conditions, and drawing out a portion of the slurry polymerization product from the main shell (200) of the reactor as a first slurry product; exchanging heat between the first slurry product and a cooling medium in a heat exchanger (100) to obtain a first slurry product after heat exchange, wherein the temperature of the first slurry product after heat exchange is lower than that of the first slurry product; and drawing the first slurry product after heat exchange back into the main shell (200); Preferably, the diluent is a C4-C6 alkane, preferably n-hexane and / or n-pentane.

22. The method according to claim 21, wherein: The temperature of the cooling medium is higher than 40°C, preferably higher than 40°C and not higher than 65°C; Preferably, the temperature of the cooling medium at the inlet of the heat exchanger (100) is higher than 40°C and not higher than 55°C; Preferably, the temperature of the first slurry product after the heat exchange is 72-85°C.

23. The method according to claim 21 or 22, wherein: The residence time of the first slurry product in the heat exchanger (100) is 1-30 seconds.

24. The method according to any one of claims 21 to 23, wherein: The method further comprises introducing a second cooling medium into the cooling jacket to exchange heat with the material inside the main shell; and / or At least a portion of the vapor phase is drawn out from the main shell through the vapor phase outlet, the vapor phase is cooled in a cooler, the cooled vapor phase is subjected to gas-liquid separation in a gas-liquid separator to obtain a liquid phase and a vapor phase, and at least a portion of the gas phase is introduced back into the main shell through the gas phase inlet.

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