Heat exchanger, reactor and application thereof and olefin polymerization method

Abstract

A heat exchanger, reactor, and application thereof, as well as an olefin polymerization method, wherein the heat exchanger comprises a shell-side cylinder, heat exchange tubes, a first tube sheet, and a first end plate. The first end plate is provided with an input through-hole and an output through-hole. A separator is provided on the surface of the first end plate facing the first tube sheet, located between the input through-hole and the output through-hole. The thickness of the separator gradually decreases, and first and second slopes are formed on either side of the separator, respectively. The first and second slopes extend to the first tube sheet. Through the above-described technical solution, the separator separates the first end plate and the first tube sheet into an input cavity and an output cavity. The slopes formed on either side of the separator provide directional flow guidance for the medium, rationally distribute the circulation space, reduce the residence time of the medium in the tube box, and thus shorten the residence time in the heat exchanger, thereby effectively suppressing wax accumulation in the heat exchanger.

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 present 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 high-volume polymer material, but my country's polyethylene production capacity is still insufficient to meet actual demand. Different polyethylene varieties typically utilize different production processes. HDPE and LLDPE are both produced using a low-pressure polyethylene process, with polymerization pressures typically below 6 MPa; while LDPE is produced using a high-pressure polyethylene process, with polymerization pressures typically exceeding 200 MPa. Polyethylene produced using the slurry polyethylene process, however, is insoluble in solvents and forms a slurry.

[0005] To control the production temperature during polyethylene production, it's necessary to promptly remove the heat generated during the process. Existing methods typically involve installing a slurry heat exchanger or gas-phase heat exchanger outside the reactor. When using a slurry heat exchanger, the reactants are cooled by the slurry heat exchanger and then 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. 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 is finally 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-to-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 operating cycle is relatively short, and it needs to be shut down for maintenance regularly, which affects 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 objectives, the present invention provides a heat exchanger on 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 outside 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, in the direction from the first end plate to the first tube sheet, the thickness of the partition gradually decreases, 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 respectively formed on both sides of the partition, and the first slope surface and the second slope surface extend to the first tube sheet.

[0009] In some embodiments, a first recessed portion is provided on a surface of the first end plate facing the first tube plate, the separator 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.

[0010] 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.

[0011] In some embodiments, a flow area of ​​the input through-hole is larger than a flow area of ​​the output through-hole.

[0012] In some embodiments, an input pipe connected to the input through-hole and an output pipe connected to the output through-hole are provided 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 provided 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-side 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 provided 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 pipe and a second connecting pipe are provided on the outer periphery of both ends of the shell-side cylinder, avoidance areas adjacent to the first connecting pipe and the second connecting pipe are provided in the shell-side cylinder, the heat exchange tube is not provided in the avoidance area, and a sealing block axially aligned with the avoidance area is provided in the second recessed portion.

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

[0018] In some embodiments, an exhaust pipe communicating with the return cavity is provided 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 provided on the second tube sheet.

[0020] In some embodiments, the heat exchange tubes are arranged in a dense to sparse arrangement from the center of the shell-side cylinder toward the edge. It should be noted that the inventors of this solution discovered for the first time that when a heat exchanger is used for slurry heat exchange, peripheral heat exchange tubes are more susceptible to or more severely clogged than central heat exchange tubes. Therefore, the distribution density of the heat exchange tubes in the peripheral area is designed to be smaller than that 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 clogging of the slurry fluid medium in the peripheral heat exchange tubes.

[0021] In some embodiments, a plurality of baffles are provided 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 further 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 pipe connected to the bottom of the main shell and a sampling assembly connected to the discharge pipe, the sampling assembly includes a sampling pipe, a liquid feeding pipe, a filter container, and a collection container, the two ends of the sampling pipe are respectively connected to the discharge pipe and the top inlet of the filter container, and the two ends of the liquid feeding pipe 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 the test line is connected to a compressed air source, and the other end is connected to the sampling line.

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

[0029] In some embodiments, the sampling assembly includes a jacket, a heating line, and a condensate line arranged outside the filter container, a filter bag is provided in the filter container, one end of the heating line is connected to the steam network and the other end is connected to the upper part of the jacket, one end of the condensate line is connected to the lower part of the jacket and the other end is connected to the steam condensate 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, and is characterized in that the method also includes drawing out a portion 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.

[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 gas phase, and drawing at least a portion of the gas phase back into the main shell through a gas phase inlet.

[0042] Through the above technical solution, the first end plate and the first tube plate are separated by a partition to form an input cavity and an output cavity, and slopes are formed on both sides of the partition to directional guide the medium, reasonably distribute the circulation space, and reduce the residence time of the medium in the tube box, thereby effectively suppressing the wax accumulation 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 lower distribution density of the heat exchange tubes in the edge part, so that the fluid flows rapidly 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, so that the overall flow rate of the fluid medium is stable, further avoiding or reducing the occurrence of wax accumulation. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 is a structural schematic diagram of the first end of the heat exchanger according to the embodiment of this scheme;

[0044] Figure 2 is a schematic structural diagram of the first end plate according to an embodiment of this solution;

[0045] Figure 3 is a cross-sectional view of the first end plate according to an embodiment of the present invention;

[0046] Figure 4 is a schematic structural diagram of the second end of the heat exchanger according to the embodiment of this scheme;

[0047] Figure 5 is a schematic structural diagram of the second end plate according to an embodiment of this solution;

[0048] Figure 6 is a cross-sectional view of the second end plate according to an embodiment of the present invention;

[0049] Figure 7 Schematic diagram of the structure of the reactor described in the embodiment of this scheme;

[0050] Figure 8 Schematic diagram of the sampling assembly described in the embodiment of this scheme.

[0051] Description of Reference Numerals

[0052] 100-heat exchanger, 110-shell-side cylinder, 111-first connecting pipe, 112-second connecting pipe, 113-baffle, 120-first tube sheet, 121-first exhaust pipe, 130-second tube sheet, 131-second exhaust pipe, 140-first end plate, 141-input through-hole, 142-output through-hole, 143-partition, 144-first recess, 145-input pipe, 146-output pipe, 147-input cavity, 148-output cavity, 150-second end plate, 151-return cavity, 152-second recess, 153-exhaust pipe, 154-sealing block, 160-heat exchange pipe, 200-main shell, 201-circulation pipeline, 202-discharge pipeline, 300-sampling assembly, 301-filtration 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-drainage pipeline, 1431-first slope, 1432-second slope, 1441-third slope, 1442-fourth slope. DETAILED DESCRIPTION

[0053] The following describes the specific embodiments of the present invention in detail with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention and are not intended to limit the present invention.

[0054] The endpoints of the ranges and any values ​​disclosed herein 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 endpoints of each range, the endpoints of each range and 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 to be specifically disclosed herein.

[0055] refer to Figures 1-6As shown, this solution 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 outside 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. The surface of the first end plate 140 facing the first tube sheet 120 is provided with a separator 143 located between the input through hole 141 and the output through hole 142. The separator 143 is provided between the first tube sheet 120 and the first end plate. 140 are separated to form an input cavity 147 and an output cavity 148 connected to the heat exchange tube 160. The partition 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 partition 143 gradually decreases. The 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. The first slope surface 1431 and the second slope surface 1432 extend to the first tube sheet 120.

[0056] The heat exchanger is a shell and tube heat exchanger, in which the shell cylinder 110 is the main structure, and its cross-section can be circular or square, etc., and a heat exchange tube 160 is provided therein. The space between the heat exchange tube 160 and the shell cylinder 110 is the shell side, and the internal space of the heat exchange tube 160 is the tube side.

[0057] 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 a hole 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.

[0058] At least one of the opposing surfaces of the first end plate 140 and the first tube plate 120 is recessed, thereby forming a cavity for accommodating fluid 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 portion of the heat exchange tubes 160, and the output cavity 148 is connected to the output through-hole 142 and another portion of the heat exchange tubes 160. The fluid passes through the input through-hole 141, the input cavity 147, and the heat exchange tubes 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 tubes 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. 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 first tube plate 120 and simply located between the two.

[0059] It can be seen that the first end plate 140 replaces the head with a flat plate-shaped partition in the prior art.

[0060] Regarding the return cavity at the other end of the shell-side cylinder 110, it can be formed by a spherical head in the prior art, or by the structure described below in this solution.

[0061] 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, eliminating the medium static area and the turbulent flow 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 the accumulation of wax or even blockage in the tube box, effectively ensuring the heat exchange effect, and extending the continuous operation cycle of the equipment.

[0062] 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. This solution optimizes the end plate structure and the structure of the input cavity 147 and the output cavity 148, so that the fluid can pass through quickly, shorten the flow time, and avoid or reduce wax accumulation and even blockage.

[0063] In addition, the first end plate 140 is made of stainless steel, and its thickness can be set to be relatively small. 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.

[0064] Among them, reference Figure 2As 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 separator 143 gradually decreases, thereby forming 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 on both sides. This 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. Compared with a plate structure with uniform thickness (whose thickness corresponds to the thickness of the separator 143 at the minimum thickness), 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 , allowing the fluid to flow 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. The second slope 1432 forms a guiding surface between the first tube sheet 120 and the output through-hole 142, allowing the fluid to flow 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 turbulent area, guide the flow of the medium fluid, make the medium flow smoother, help reduce pressure drop, reduce material accumulation and blockage, ensure that the fluid passes through the input cavity, output cavity and heat exchange tube 160 more smoothly, and avoid or reduce wax accumulation or even blockage.

[0065] Among them, reference Figure 2 As shown, the surface of the first end plate 140 facing the first tube sheet 120 is provided with a first recessed portion 144. The separator 143 is disposed in the first recessed portion 144. The first recessed portion 144 is formed with a third sloped surface 1441 extending to the edge of the input through-hole 141 and a fourth sloped surface 1442 extending to the edge of the output through-hole 142. In other embodiments, recessed portions may also be provided on the tube sheet. In this embodiment, the first tube sheet 120 adopts a conventional tube sheet structure. Instead of a conventional spherical end cap, the first end plate 140 is a generally flat plate. The first recessed portion 144 is provided thereon and separated by the separator 143 to form two recessed portions, thereby forming an input cavity 147 and an output cavity 148 in conjunction with the first tube sheet 120. 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 2In the figure, the first recessed portion 144 is provided with two third slope surfaces 1441 located on both sides of the first slope surface 1431 around the input through-hole 141. The two third slope surfaces 1441 form guide surfaces between the input through-hole 141 and the first tube sheet 120. Similar to the first slope surface 1431, the third slope surfaces 1441 can guide fluid flow and reduce flow dead angles. The first recessed portion 144 is provided with two fourth slope surfaces 1442 located on both sides of the second slope surface 1432 around the output through-hole 142. The two fourth slope surfaces 1442 form guide surfaces between the output through-hole 142 and the first tube sheet 120. Similar to the second slope surface 1432, the fourth slope surface 1442 can guide fluid flow and reduce flow dead angles.

[0066] Furthermore, the first slope 1431 and the third slope 1441 transition smoothly to form a smooth, gradually expanding wall defining the input cavity 147; the second slope 1432 and the fourth slope 1442 transition smoothly 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, which is divided into two semicircular interfaces by the divider 143. The ends of the input cavity 147 and the output cavity 148 facing the first tube sheet 120 are also semicircular interfaces. The first slope 1431 and the third slope 1441 form a smooth transition between the input through-hole 141 and the semicircular interface, guiding fluid to flow more quickly from the input through-hole 141 to the first tube sheet 120. The second slope 1432 and the fourth slope 1442 also form a smooth transition between the output through-hole 142 and the semicircular interface, guiding fluid to flow more quickly from the first tube sheet 120 to the output through-hole 142. The input cavity 147 and the output cavity 148 are both 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, forming a tapered structure, which can reduce flow dead angles, reduce the cavity volume, and allow the fluid to pass through more quickly, thereby increasing the flow rate. 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 the input through hole 141 or the output through hole 142 can be set on the flat bottom surface. The corresponding slope surfaces described above are set around the flat bottom surface, and a smooth transition does not need to be formed between adjacent slope surfaces.

[0067] When the input cavity 147 is formed into a gradually expanding shape, the axial dimension of the edge portion is smaller, and thus the volume of the edge portion of the input cavity 147 is smaller. It should be noted that the inventors of this solution discovered for the first time that when the heat exchanger is used for slurry heat exchange, the peripheral heat exchange tubes are more susceptible to clogging or more severe clogging than the central heat exchange tubes. A portion of the edge of the input cavity 147 corresponds to the edge portion of the shell-side cylinder 110, that is, to the heat exchange tubes 160 in the peripheral portion. Therefore, the smaller edge portion of the input cavity 147 adapts to the smaller flow rate of the heat exchange tubes 160 in the peripheral edge portion of the shell-side 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, allowing the medium fluid to flow rapidly in the heat exchange tubes 160 in the peripheral edge portion, ensuring the overall flow rate of the medium fluid and avoiding wax accumulation or even clogging. The output cavity 148 has a similar mechanism and will not be described in detail here.

[0068] 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 can be provided with flanges to facilitate connection with other pipe fittings.

[0069] refer to Figure 2 and Figure 3 As shown, the flow area of ​​input through-hole 141 is larger than the flow area of ​​output through-hole 142. This allows the flow rate of the input fluid to be greater than the flow rate of output through-hole 142. This is suitable for situations where the volume of the fluid decreases after the fluid temperature decreases, such as partial gas liquefaction. The ratio of the flow area of ​​input through-hole 141 to the flow area of ​​output through-hole 142 is 18:10 to 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. Furthermore, the smaller flow area of ​​output through-hole 142 facilitates faster flow of the medium fluid through output tube 146, preventing wax accumulation or even blockage in output tube 146. Correspondingly, the slopes on both sides of the partition 143 are also different. The slope of the first slope 1431 is greater than the slope of the second slope 1432 , and the slope of the third slope 1441 is also greater than the slope of the fourth slope 1442 .

[0070] In addition, reference 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.

[0071] 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.

[0072] The heat exchanger also 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 outside of the second tube sheet 130. A return cavity 151, which is connected to the heat exchange tubes 160, is formed between the second end plate 150 and the second tube sheet 130. The volume of the return cavity 151 gradually decreases from the center to the edge. A recess is formed on at least one of the opposing surfaces of the second tube sheet 130 and the second end plate 150, forming the return cavity 151 therebetween. A first portion of the heat exchange tubes 160 connected to the input cavity 147 inputs fluid into the return cavity 151, which is then fed into the second portion of the heat exchange tubes 160 and returned to the output cavity 148. It should be noted that the inventor of this solution discovered for the first time that when the heat exchanger is used for slurry heat exchange, the peripheral heat exchange tube is more likely to be clogged or the degree of clog is more serious than that of the central heat exchange tube. The volume of the edge part of the return cavity 151 is smaller, so that the fluid can flow quickly through the edge part of the return cavity 151 (to quickly leave or enter the peripheral heat exchange tube 160), thereby allowing the fluid medium in the heat exchange tube 160 at the peripheral edge part to have sufficient flow rate and flow velocity, thereby avoiding blockage in the peripheral heat exchange tube 160.

[0073] Specifically, refer to Figure 5 As shown, the surface of the second end plate 150 facing the second tube sheet 130 is provided with a second recessed portion 152. The cross-sectional area of ​​the second recessed portion 152 gradually decreases as it moves away from the second tube sheet 130. The second tube sheet 130 has a larger number of heat exchange tubes 160 arranged in the center and a smaller number of heat exchange tubes 160 arranged at the edges. Therefore, the axial dimension of the edge portion of the second recessed portion 152 is smaller than that of the center portion, and the space is also relatively smaller. That is, the center portion of the return cavity 151 has a larger space, while the edge portion has a smaller space. This adapts to the flow distribution of the fluid at different locations, ensuring that the fluid has essentially the same flow rate and flow velocity in the peripheral heat exchange tubes 160 and the central heat exchange tube 160, thereby avoiding or alleviating the problem of blockage in the peripheral heat exchange tubes 160. The maximum depth of the second recessed portion 152 is 12-15 mm. The second recessed portion 152 is conical or frustum-shaped.

[0074] Among them, the second recessed portion 152 is conical, and the first connecting pipe 111 and the second connecting pipe 112 are provided 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 pipe 111 and the second connecting pipe 112, respectively. The heat exchange tube 160 is not provided in the avoidance area, and 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 provided, 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, as shown in FIG. Figure 5 shown.

[0075] The first connecting tube 111 and the second connecting tube 112 are both connected to the interior of the shell-side cylinder 110, that is, connected to the shell side, and can be used to input and output heat exchange fluids. Their free ends can be provided with flanges to facilitate connection with other pipe fittings. In particular, no heat exchange tube 160 is provided on the tube sheet near the connection point between the first connecting tube 111 and the second connecting tube 112, forming an avoidance area. That is, no heat exchange tube 160 is provided to avoid the fluid about to flow into or out of the first connecting tube 111 and the second connecting tube 112, thereby ensuring medium flow space at the shell-side inlet and outlet positions. The area of ​​the second tube sheet 130 where the heat exchange tube 160 is not provided is arched. Therefore, the blocking block 154 provided 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 provided, thereby occupying the area of ​​the second tube sheet 130 where the heat exchange tube is not provided, avoiding the formation of a medium stagnation zone and turbulent flow zone there.

[0076] Wherein, 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 arranged symmetrically about the central axis of the shell-side cylinder 110. Since the second recessed portion 152 does not extend to the arched area occupied by the blocking block 154, it forms an approximate conical shape, which is equivalent to a cone with the arched portion cut off. In other words, a conical recessed area with the arched 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 5In addition, the first connecting pipe 111 and the second connecting pipe 112 are located at both ends of the shell-side 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-side cylinder 110. Accordingly, the circumferential angle between 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 between 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.

[0077] An exhaust pipe 153 communicating with the return chamber 151 is provided on one side of the second end plate 150 facing away from the second tube plate 130. The exhaust pipe 153 can discharge gas or liquid in the return chamber. The exhaust pipe 153 remains disconnected during normal use and can be opened for maintenance.

[0078] In addition, a second exhaust pipe 131 is provided on the second tube sheet 130 and is connected to the shell-side cylinder 110. The second exhaust pipe 131 has similar functions to the first exhaust pipe 121 and will not be described again here.

[0079] 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 can be a circular cylinder, and 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 inventors of this solution 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 clogged or the degree of clog is more serious 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, so as 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 clogging of the slurry fluid medium in the peripheral heat exchange tubes.

[0080] This solution is specifically designed to address the problem of clogging or more serious clogging 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, allowing the fluid to 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. These two aspects, combined with each other, ensure the flow rate and flow velocity of the medium fluid in the peripheral heat exchange tubes, thereby avoiding or reducing clogging problems.

[0081] Wherein, a plurality of baffles 113 are provided inside the shell-side cylinder 110. Figure 1 and Figure 4As 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 tube 160.

[0082] On the other hand, reference Figure 7 As shown, the present solution provides a reactor, wherein the reactor includes a main shell 200 and the heat exchanger 100 described in the above solution, 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 provided on the circulation pipeline 201.

[0083] The main shell 200 can serve as a reaction carrier, and the circulation pipeline 201 can discharge 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.

[0084] In addition, reference Figure 8 As shown, the reactor includes a discharge pipe 202 connected to the bottom of the main housing 200 and a sampling assembly 300 connected to the discharge pipe 202. The sampling assembly 300 includes a sampling pipe 303, a liquid feeding pipe 306, a filter container 301, and a collection container 302. The two ends of the sampling pipe 303 are respectively connected to the discharge pipe 202 and the top inlet of the filter container 301, while the two ends of the liquid feeding pipe 306 are respectively connected to the bottom outlet of the filter container 301 and the top inlet of the collection container 302. The discharge pipe 202 can discharge the reaction products in the main housing 200; the sampling assembly 300 is used to remove some of the material in the discharge pipe 202 for sampling and detection of the reaction products.

[0085] 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.

[0086] In addition, a control valve is provided on the discharge line 202, and the sampling line 303 is connected to the control valve. The control valve, such as a plunger valve, is provided on the discharge line 202 to control the connection and disconnection of the sampling line 303. When disconnected, the reaction products in the discharge line 202 will not enter the sampling line 303, thereby preventing the reaction products from being retained in the sampling line 303. In other embodiments, a three-way valve may also be provided on the discharge line 202, the main purpose of which is to prevent material from entering the sampling line 303 when sampling is not in progress.

[0087] In addition, reference Figure 8 As shown, the sampling assembly 300 includes a test line 304, one end of which is connected to a compressed air source and the other end is connected to the sampling line 303. Before sampling, when the sampling line 303 is disconnected from the discharge line 202, compressed gas (e.g., nitrogen) can be passed through the test line 304 to the various lines, the filter container 301, and the collection container 302 to check the airtightness of the lines.

[0088] In addition, the sampling assembly 300 includes a pre-cleaning line 305, one end of which is connected to a cleaning solvent container and the other end is connected to the sampling line 303. The cleaning solvent can be introduced into the sampling line 303 through the pre-cleaning line 305 to clean residual reaction products to avoid affecting the sampling and detection. The pre-cleaning operation can be performed before the sampling operation to ensure the accuracy of the sampling and detection.

[0089] In addition, the sampling assembly 300 includes a jacket disposed outside the filter container 301, a heating line 307, and a condensate line 308. A filter bag is disposed within the filter container 301. One end of the heating line 307 is connected to the steam network and the other end is connected to the upper portion of the jacket. One end of the condensate line 308 is connected to the lower portion of the jacket and the other end is connected to the steam-condensate network. The filter bag is used to filter the reaction products to achieve solid-liquid separation. Steam can be introduced into the jacket via the heating line 307 to heat the filter container 301, evaporating any liquid remaining in the filter container 301 after filtration, thereby discharging hydrocarbons from the sampling system and safely opening the filter. The steam in the jacket condenses to form condensate, which is returned to the steam-condensate network via the condensate line 308. In other embodiments, an electric heater can also be used to heat the filter container 301.

[0090] In addition, reference Figure 8 As shown, the sampling assembly 300 includes an exhaust line 309 connected to the top outlet of the collection container 302 and a drain line 310 connected to the bottom outlet of the collection container 302. The exhaust line 309 can exhaust nitrogen (e.g., introduced from the test line 304 during testing) during replacement to prevent residual hydrocarbon gas inside. When a large amount of solution is stored in the collection container 302, the bottom drain line 310 can be opened to drain the solution.

[0091] This solution also provides the use of the above-mentioned reactor in a slurry reaction. Preferably, the slurry reaction is olefin slurry polymerization.

[0092] On the other hand, the present embodiment provides an olefin polymerization method, which adopts the reactor described above, and includes 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 portion 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 being lower than the temperature of the first slurry product, and drawing the first slurry product after heat exchange back into the main shell.

[0093] 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.

[0094] In a particularly preferred embodiment, the diluent is n-pentane. The inventors have discovered that using n-pentane as a diluent in polyethylene slurry polymerization processes results in mild reaction conditions and enables solvent recovery with significantly lower energy consumption, making this solution suitable for large-scale industrial production. The low solubility of n-pentane in oligomers helps achieve a new balance between the mechanical properties and processing performance of high-density polyethylene.

[0095] 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 precipitation and accumulation of wax in the polymer slurry 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 1-30 seconds. 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.

[0096] In a preferred embodiment, the temperature of the first slurry product after the heat exchange is 72-85°C.

[0097] 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.

[0098] In a preferred embodiment, the method further includes withdrawing at least a portion of the vapor phase from the main housing through a vapor phase outlet, cooling the vapor phase in a cooler, subjecting the cooled vapor phase to gas-liquid separation in a gas-liquid separator to produce a liquid phase and a vapor phase, and returning at least a portion of the vapor phase to the main housing through a vapor phase inlet. The inventors have discovered that in this preferred embodiment, the method of this solution rarely or never reduces production capacity due to film formation on the walls of the polymerization reactor. Furthermore, this method can utilize conventional cooling water, as described in the aforementioned heat exchanger of the present invention, rather than chilled water. Furthermore, in this preferred embodiment, the heat removal efficiency per unit volume of the polymerization reactor is high, and can even remove all heat from the polymerization reactor.

[0099] Preferably, the olefin is ethylene, or a combination of ethylene and at least one monomer selected from 1-hexene, 1-butene, and 1-octene.

[0100] According to a preferred embodiment, the olefin is ethylene.

[0101] According to another preferred embodiment, the olefin is a combination of ethylene and at least one monomer selected from 1-hexene and 1-butene.

[0102] Preferably, the olefin polymerization catalyst is one or more selected from Ziegler-Natta catalyst (ZN), metallocene catalyst and non-metallic catalyst.

[0103] This solution 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 with a diluent to a certain concentration and then added to the polymerization reactor using a metering pump.

[0104] 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.

[0105] Preferably, in the polymerization reactor of the scheme, the weight ratio of the olefin to the hydrogen is 800-1500:1.

[0106] Preferably, in the polymerization reactor of this embodiment, the amount of the catalyst used is 0.01 g to 0.1 g per 1 kg of olefin.

[0107] Preferably, the amount of the diluent is such that the concentration of the slurry at the bottom of the polymerization reactor is 35-42 wt%, preferably 37-40 wt%.

[0108] The method of this 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 based on the designed temperature difference requirements and the temperature of the cooling medium. Specific data values ​​are provided as examples in the examples below of the present invention, which should not be understood by those skilled in the art as limiting the present invention.

[0109] The method of this scheme has no special requirements for the post-processing operation of the slurry polymerization product, and can be carried out using the operation methods 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 a slurry external circulation pump, and then the unreacted ethylene monomer and hydrogen can be separated by flash distillation. 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 a high-speed rotating horizontal centrifuge through a slurry delivery pump and separated into polymer wet cake and mother liquor. Part of the mother liquor is recycled, and part is recovered in the solvent recovery unit. The wet cake enters the dryer for drying and then enters the degassing bin for further drying. It is then sent to the blending system through the air conveying system for blending and then sent to the packaging system.

[0110] The method of the present invention has no particular requirements for the ratio of the raw materials involved in the polymerization reaction (e.g., olefins, olefin polymerization catalysts, diluents, hydrogen, etc.), and can be carried out using parameters and conditions known in the art. Several dosage relationships are exemplified below in the present invention, which should not be construed as limiting the present invention by those skilled in the art.

[0111] The polymerization reactor of the present invention is preferably at least three reactors arranged in parallel.

[0112] 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.

[0113] 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:

[0114] Ethylene (the ethylene introduction rate of each reactor was 60.63 kg / h) and hydrogen (the hydrogen introduction rate of each reactor was 0.048 g / h) were introduced into the polymerization reactor and dispersed in pentane. At the same time, a catalyst was introduced (3.7 g / h of BCE catalyst (purchased from Sinopec Catalyst Co., Ltd. Beijing Aoda Branch) was introduced into each reactor). The concentration of the slurry at the bottom of the polymerization reactor was 38.8 wt%, and the temperature of the polymerization reactor was controlled in the range of 75-78°C.

[0115] Example 1

[0116] This embodiment applies the present invention Figures 1 to 6 The heat exchanger shown in FIG 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 separator 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 separator, the first end plate is provided with a first recessed portion, the separator is provided 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).

[0117] The conditions of the three polymerization reactors in this embodiment are the same. The conditions of one polymerization reactor are listed as follows: the temperature of the cooling medium in the heat exchanger is 47°C at the inlet and 57.1°C at the outlet. 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 heat exchanger outlet is 83℃, and the average residence time of the slurry in the heat exchanger is 1.2s.

[0118] The performance indexes of the polyethylene product obtained in this example are distributed within 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 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.

[0119] The plant scale of this embodiment is a pilot plant of 14,400 t / year, and no wax accumulation occurred during the 48-month continuous operation of the plant.

[0120] Example 2

[0121] 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 using the same separator as in embodiment 1. 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 separator.

[0122] 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.

[0123] The plant scale of this embodiment is a pilot plant of 14,400 t / year, and no wax accumulation occurred during the 27 months of continuous operation of the plant.

[0124] Example 3

[0125] The difference between this embodiment and embodiment 1 is that the return cavity is cylindrical and no blocking block is provided. The inner diameter of the return cavity is the same as the maximum inner diameter of the conical return cavity in embodiment 1.

[0126] 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.

[0127] The device scale of this embodiment is a pilot device of 14,400 t / year, and no wax accumulation occurred during the 30 months of continuous operation of the device.

[0128] Example 4

[0129] 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 using the same partition as in embodiment 1. 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. 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 flow area of ​​the input through-hole is the same as the flow area of ​​the output through-hole; and (4) 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.

[0130] 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.

[0131] The plant scale of this embodiment is a pilot plant of 14,400 t / year, and no wax accumulation occurred during the 23 months of continuous operation of the plant.

[0132] Example 5

[0133] 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.

[0134] 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.

[0135] The device scale of this embodiment is a pilot device of 14,400 t / year, and no wax accumulation occurred during the 20 months of continuous operation of the device.

[0136] Comparative Example 1

[0137] The heat exchanger used in Comparative Example 1 has a slightly different structure from the heat exchanger in Example 4. The difference is that the heat exchanger in Comparative Example 1 does not have a special-shaped partition, the partition in the heat exchanger is a partition with uniform thickness, and the thickness of the partition is the smallest thickness among the partitions in the heat exchanger in Example 4.

[0138] The conditions of the three polymerization reactors in Comparative Example 1 are the same. The conditions of one polymerization reactor 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 and 60°C at the outlet. 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 heat exchanger outlet is 83℃, and the average residence time of the slurry in the heat exchanger is 1.2s.

[0139] 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 / cm3 within the range.

[0140] Results: The device scale of comparative example 1 is a pilot device with a capacity of 14,400 t / year. Wax accumulation occurred after the device was in continuous operation for 21 months.

[0141] 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.

[0142] Comparative Example 2

[0143] Comparative Example 2 was carried out using the same heat exchanger as in Comparative Example 1.

[0144] The conditions of the three polymerization reactors in Comparative Example 2 are the same. The conditions of one polymerization reactor 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 51°C at the outlet. 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 heat exchanger outlet is 83℃, and the average residence time of the slurry in the heat exchanger is 1.2s.

[0145] 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.

[0146] Results: The device scale of comparative example 2 is a pilot device with a capacity of 14,400 t / year. Wax accumulation occurred after the device was in continuous operation for 17 months.

[0147] 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.

[0148] It can be seen from the experimental results of Examples 1-5 and Comparative Examples 1-2 that, when polyethylene is prepared using the device using the heat exchanger of the present invention, while obtaining a product with good processing performance, the device has a long continuous operation cycle. By optimizing the heat exchanger structure, 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, especially ensuring that the fluid in the heat exchange tube corresponding to the outer edge portion has a sufficiently high flow rate, avoiding or reducing the wax accumulation phenomenon in the heat exchanger, and effectively extending the stability time of the heat exchanger.

[0149] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, the technical solution of the present invention may be subjected to a variety of simple modifications, including combining the various specific technical features in any suitable manner. 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 disclosed in the present invention and fall within the scope of protection 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 a first end of the shell-side cylinder (110), and a first end plate (140) connected to the outside 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 provided on the first tube sheet. An input cavity (147) and an output cavity (148) communicating with the heat exchange tube (160) are formed between the plate (120) and the first end plate (140); in a direction from the first end plate (140) to the first tube plate (120), the thickness of the partition (143) gradually decreases; 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) are respectively formed on both sides of the partition (143); the first slope surface (1431) and the second slope surface (1432) extend to the first tube plate (120); A first recessed portion (144) is provided on a surface of the first end plate (140) facing the first tube plate (120), 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 an edge of the input through hole (141) and a fourth slope (1442) extending to an edge of the output through hole (142); 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); and 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).

2. The heat exchanger according to claim 1, 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).

3. The heat exchanger according to claim 1, wherein The first tube sheet (120) is provided with a first drain pipe (121) connected to the shell-side cylinder (110).

4. The heat exchanger according to claim 1, 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 outside 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.

5. The heat exchanger according to claim 4, 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).

6. The heat exchanger according to claim 5, wherein: The second recessed portion (152) is conical, and a first connecting pipe (111) and a second connecting pipe (112) are provided 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 pipe (111) and the second connecting pipe (112), respectively. The heat exchange tube (160) is not provided in the avoidance area, and a blocking block (154) axially aligned with the avoidance area is provided in the second recessed portion (152).

7. The heat exchanger according to claim 6, 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 recess (152) and are symmetrically arranged about the central axis of the shell-side cylinder (110).

8. The heat exchanger according to claim 4, 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).

9. The heat exchanger according to claim 4, wherein: The second tube sheet (130) is provided with a second drain pipe (131) connected to the shell-side cylinder (110).

10. The heat exchanger according to claim 1, wherein The arrangement density of the heat exchange tubes is arranged from dense to sparse in a direction from the center toward the edge of the shell-side cylinder (110).

11. The heat exchanger according to claim 1, wherein A plurality of baffles (113) are provided inside the shell-side cylinder (110).

12. 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 11, wherein the main shell (200) is provided with a first opening at an upper portion and a second opening at a lower portion, 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).

13. The reactor according to claim 12, wherein A cooling jacket is provided on at least part of the wall of the main shell (200).

14. The reactor according to claim 12 or 13, wherein The reactor further comprises 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), 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 communicated with the inlet of the material to be cooled of the cooler, and the gas phase inlet is communicated with the gas phase flow outlet of the gas-liquid separator.

15. The reactor according to claim 12, wherein The reactor further comprises a discharge pipeline (202) connected to the bottom of the main shell and a sampling assembly (300) connected to the discharge pipeline (202). The sampling assembly (300) comprises a sampling pipeline (303), a liquid feeding 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). The two ends of the liquid feeding pipeline (306) are respectively connected to the bottom outlet of the filter container (301) and the top inlet of the collection container (302).

16. The reactor according to claim 15, wherein A control valve is provided on the discharge pipeline (202), and the sampling pipeline (303) is connected to the control valve.

17. The reactor according to claim 15, wherein The sampling assembly (300) further comprises a test pipeline (304), one end of the test pipeline (304) being connected to a compressed air source, and the other end being connected to the sampling pipeline (303).

18. The reactor according to claim 15, wherein The sampling assembly (300) further comprises a pre-cleaning pipeline (305), one end of which is connected to a cleaning solvent container, and the other end of which is connected to the sampling pipeline (303).

19. The reactor according to claim 15, wherein The sampling assembly (300) further comprises 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.

20. The reactor according to claim 15, wherein The sampling assembly (300) further comprises an exhaust pipe (309) connected to the top outlet of the collection container (302) and a drain pipe (310) connected to the bottom outlet of the collection container (302).

21. The reactor according to claim 15, wherein The sampling assembly (300) further comprises a heater disposed on the filter container (301).

22. The reactor according to claim 12, wherein The main housing (200) is constructed in a kettle type.

23. Use of the reactor according to claim 12 in a slurry reaction.

24. Use of the reactor according to claim 23 in a slurry reaction, wherein the slurry reaction is olefin slurry polymerization.

25. A method for olefin polymerization, characterized in that: The method adopts the reactor described in any one of claims 12 to 22.

26. The method according to claim 25, 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).

27. The method according to claim 26, wherein The diluent is a C4-C6 alkane.

28. The method according to claim 27, wherein The diluent is n-hexane and / or n-pentane.

29. The method according to claim 28, wherein The temperature of the cooling medium is higher than 40°C.

30. The method according to claim 29, wherein The temperature of the cooling medium is higher than 40°C and not higher than 65°C.

31. The method according to claim 30, wherein 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; and / or, The temperature of the first slurry product after the heat exchange is 72-85°C.

32. The method of claim 26, wherein: The residence time of the first slurry product in the heat exchanger (100) is 1-30 seconds.

33. The method according to any one of claims 26 to 32, 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 vapor phase is introduced back into the main shell through the vapor phase inlet.

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