Reaction device for preparing polyolefin by solution method

Abstract

The invention belongs to the technical field of preparation devices by a solution method, and provides a reaction device for preparing polyolefin by a solution method. The reaction device comprises a barrel and a stirrer, the stirrer is arranged in the axis center of the barrel of the reaction device, at least two sets of first heat exchangers are annularly arranged in the barrel of the reaction device, each first heat exchanger comprises at least two vertical heat exchange pipes, and inlets and outlets of the first heat exchangers are located in the bottom of the reaction device; a second heat exchanger is attached to the outer wall of a barrel of the reaction device, a blocking pipe is axially inserted into a gap between the first heat exchanger and the inner wall of the barrel of the reaction device, and the blocking pipe can damage a flowing boundary layer on the surfaces of the first heat exchanger and the inner wall of the barrel of the reaction device. The invention aims to solve the problems of low mass transfer and heat transfer efficiency, non-uniform mixing, local overheating, wall hanging, scaling and unsmooth discharging of the solution polymer high-viscosity material system, large number of heat exchange components in the reactor and difficulty in structural design of the solution polymer high-viscosity material system.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of chemical production, and provides a reaction device for preparing polyolefin by a solution method. BACKGROUND

[0002] In the preparation of polyolefin by a solution method, the inlet reactant, the reaction catalyst and the outlet product of the reaction kettle are all solutions. The solution polymer has the problems of low mass transfer and heat transfer efficiency, uneven mixing and local overheating; the solution polymer has the problems of wall sticking, fouling and poor discharging; the reactor has the problems of a large number of internal heat exchange components and difficult structure design; and the reactor has the problem of difficult internal cleaning. The polymeric reaction kettle with a dry powder catalyst feeding system in the prior art CN 223096746U comprises a polymeric reaction kettle, a feeding system, a venting system, a nitrogen feeding system, a raw material feeding system and a vacuum pumping system. The feeding system comprises a catalyst sampler and a catalyst feeder which are connected through a first catalyst feeding pipe, the catalyst sampler and the catalyst feeder are both connected with the first catalyst feeding pipe through first pipe joints, the catalyst feeder is connected with the second catalyst feeding pipe through second pipe joints, the polymeric reaction kettle and the catalyst feeder are both connected with the venting system, the nitrogen feeding system is connected with the catalyst feeder and the polymeric reaction kettle, the raw material feeding system is connected with the polymeric reaction kettle and the catalyst feeder, and the vacuum pumping system is connected with the polymeric reaction kettle. The inventor of the prior art catalyst believes that the prior art has a large room for improvement. SUMMARY

[0003] The application aims to solve the problems of low mass transfer and heat transfer efficiency, uneven mixing and local overheating of the solution polymer with high viscosity. Secondly, the problems of wall sticking, fouling and poor discharging of the solution polymer with high viscosity are solved; the problems of a large number of internal heat exchange components and difficult structure design of the reactor are solved, and the problem of difficult internal cleaning of the reactor is solved.

[0004] The application relates to a reaction device for preparing polyolefin by a solution method, which comprises a cylinder and a stirrer, the axis of the cylinder of the reaction device is provided with the stirrer, at least two groups of first heat exchangers are arranged in the cylinder of the reaction device in a ring shape, the first heat exchanger comprises at least two vertical heat exchange pipes, the inlet and outlet of the first heat exchanger are located at the bottom of the reaction device, the outer wall of the cylinder of the reaction device is attached with a second heat exchanger, and the gap between the first heat exchanger and the inner wall of the cylinder of the reaction device is axially inserted with a baffle pipe, the baffle pipe can destroy the flow boundary layer on the surface of the first heat exchanger and the inner wall of the cylinder of the reaction device. Through the above arrangement, the top of the heat exchange pipe of the first heat exchanger is connected by an elbow, the first heat exchanger is a U-shaped pipe, one end of the U-shaped pipe bundle is fixed, and the other end can be freely stretched and contracted, can compensate the thermal expansion difference caused by temperature change below 300 DEG C, eliminate the temperature difference stress generated by the different thermal expansion coefficients of the pipe bundle and the shell, solve the heat compensation problem of the pipe bundle cooling system; the cooling medium in the first heat exchanger is usually desalted water, the heat exchange pipe adopts a high-flux pipe, the surface of the heat exchange pipe has a microporous structure or other structure for increasing the surface area for heat dissipation, and can greatly promote the boiling heat transfer of the solution outside the pipe; the outer portion of the reaction device is provided with the second heat exchanger, different circulating media are input into the second heat exchanger according to different reaction stages, low-pressure steam is input into the second heat exchanger to heat the reaction device before and at the beginning of the reaction, the reaction device reaches the reaction temperature, the circulating medium of the second heat exchanger adopts desalted water after the reaction is stable and after the reaction is finished, and the reaction solution is cooled by the first heat exchanger, the reaction device is cooled simultaneously from the inside and the outside, the heat transfer efficiency is improved, meanwhile, the bottom and the top of the reaction device can be ensured to have no heat transfer dead angle; 4-8 baffle pipes are arranged between the first heat exchanger and the inner wall of the cylinder of the reaction device, at least two finger-shaped rods are arranged on the outer wall of the baffle pipe, the baffle pipe can destroy the flow boundary layer near the surface of the inner wall when rotating, the surface is prevented from forming tiny adhesion, the heat transfer effect of the cylinder is maintained, and the tiny adhesion is prevented from growing into fouling, if the material adheres to the wall of the heat exchange pipe and the inner wall of the reactor, the adhesion thickness is continuously increased, the adhesion grows into fouling, the thermal resistance formed by the adhesion layer is continuously increased, the wall-hanging will cause the heat transfer efficiency to be greatly reduced, and the product of the reaction device is prone to be unqualified due to the high residual monomer content.

[0005] As preferred, the top and the bottom of the cylinder are hemispherical surfaces, the middle part of the cylinder is a cylindrical surface, the second heat exchanger comprises a half-pipe structure, the half-pipe structure is a tubular structure cut along the extending direction, the open surface of the half-pipe structure is a heat conduction surface, and the closed surface of the half-pipe structure is a heat dissipation surface, the heat conduction surface is attached to the outer wall of the cylinder. The circulating medium in the half-pipe structure exchanges heat with the reaction solution in the cylinder through the heat conduction surface, the heat conduction surface of the half-pipe structure has a large heat dissipation area because the open surface has a large heat dissipation area, and the heat conduction surface is only separated from the reaction solution by the cylinder, so the heat transfer efficiency of the half-pipe structure is high, and the heat transfer efficiency between the half-pipe structure and the reaction solution is high.

[0006] As preferred, the half-pipe structure comprises a spiral half-pipe, a collection half-pipe and a vertical half-pipe connected to the collection half-pipe at both ends, the top and bottom of the cylinder body are attached to the heat-conducting surface of the spiral half-pipe, and the middle part of the cylinder body is attached to the heat-conducting surface of the collection half-pipe and the vertical half-pipe. The half-pipe structure coats each surface of the cylinder body of the reaction device, and different shapes of half-pipes cooperate with different flow fields of different parts of the reaction device to avoid dead corners of heat transfer at the bottom and top of the cylinder body.

[0007] As preferred, the outer wall of the baffle pipe is provided with a finger-shaped rod, the included angle between the finger-shaped rod and the outer wall of the baffle pipe is 15-90°, and the end of each finger-shaped rod is provided with a rotating nozzle. Through the above setting, the baffle pipe can input hot solvent which does not participate in the reaction but has a temperature close to the reaction temperature, and the hot solvent is sprayed out by the rotating nozzle. The finger-shaped rod not only acts as a turbulence element, but also can cooperate with the hot solvent to blow, so as to form a sustained fluid shear force to clean the inner wall of the cylinder body and the outer surface of the heat exchange tube of the first heat exchanger. The polymer in the production of polyolefin belongs to a high-viscosity system, and the system has poor fluidity, which is prone to problems such as wall sticking and sticking. The fluid shear force can peel off the material adhesion on the inner wall of the cylinder body and the outer surface of the heat exchange tube of the first heat exchanger, prevent it from growing into scale, solve the problem that the thickness of the material adhesion increases after growing, the thermal resistance of the material adhesion layer also increases, and the heat transfer efficiency decreases, and the product residual single content is high and does not meet the standard. The hot solvent is separated from the reaction product through subsequent processes.

[0008] As preferred, the cylinder body is provided with at least two discharge ports, the discharge ports include a first discharge port and a second discharge port, the first discharge port is located in the middle of the cylinder body, and the second discharge port is located at the top of the cylinder body. When the reactor is not full, the operator uses the first discharge port provided on the side wall of the cylinder body of the reaction device to discharge, compared with the traditional discharge port located at the bottom, the fluid kinetic energy and gravity are used to guide the smooth discharge of the product while reducing the back mixing phenomenon, that is, reducing the phenomenon that part of the fluid in the reaction device flows upward under the action of the stirrer and then flows backward on the cross section of the flow channel under the influence of the fluid kinetic energy and gravity. When the material height is level with the first discharge port, the back mixing phenomenon almost does not occur, and when the material height is slightly higher than the first discharge port, only the material above the first discharge port part occurs back mixing phenomenon; further, when the reactor is full, the operator uses the second discharge port provided on the top of the cylinder body of the reaction device to discharge, compared with the traditional discharge port located at the bottom and the above discharge port located on the side wall of the cylinder body, the second discharge port is located at the top of the reaction device, which can greatly reduce the back mixing phenomenon, make the reaction more sufficient and uniform, shorten the material residence time distribution, and improve the reaction efficiency.

[0009] As preferred, the center line of the first discharge port has an angle of 15-75° downward with the horizontal plane. Through the above setting, the structure can make full use of the kinetic energy of fluid and gravity to guide the smooth discharge of the product, effectively avoiding the accumulation and blockage of the polymer in the outlet area.

[0010] As preferred, the stirrer comprises a vertical stirring rod and a paddle mechanism sleeved outside the stirring rod, the paddle mechanism comprises radial flow paddles located at the end of the stirring rod and at the bottom of the reaction device, and at least one layer of axial flow paddles arranged along the extension direction of the stirring rod, rotation of the radial flow paddles generates radial turbulent flow perpendicular to the stirring rod, and rotation of the axial flow paddles generates axial flow parallel to the stirring rod. The stirrer is provided with multiple layers of stirring paddles from bottom to top, the bottom layer is a radial flow paddle with large blades perpendicular to the stirring plane, used to generate strong radial turbulent flow at the bottom of the reaction device to realize rapid and uniform mixing of the liquid catalyst and the reactant solution, and the layers above the bottom layer are axial flow paddles with an angle with the stirring plane or with curvature, which can push the polymer in the reaction device to flow upward as a whole along the axial direction, cooperating with the radial turbulent flow at the bottom to form a flow field covering the inside of the reaction device.

[0011] As preferred, the second heat exchanger is matched with the paddle mechanism, and the planes where the radial flow paddles and the axial flow paddles of the paddle mechanism are respectively arranged are provided with collection half-pipes. During stirring of the stirrer, the part of the paddle mechanism directly contacted with the reaction solution has higher heat due to stirring friction and heat generated by the paddle driving the reaction solution than other positions of the flow field. The collection half-pipes are arranged at the plane positions to shorten the heat exchange path, secondly, compared with vertical half-pipes, the open surface of the collection half-pipes surrounds the annular surface of the plane position of the reaction device cylinder, and there is a wall thickness between adjacent vertical half-pipes, while the collection half-pipes do not have discontinuity, and thirdly, although the axial flow paddles mainly generate axial flow, in fact, they also generate part of the radial flow generated by the radial flow paddles, and the open surface of the collection half-pipes can also better adapt to the horizontal flow field. In addition, through the above setting, the vertical half-pipes connected with the collection half-pipes at both ends can also efficiently dissipate heat for the area mainly generated by the axial flow paddles, and the open surface of the vertical half-pipes can better adapt to the axial flow field. The collection half-pipes and the vertical half-pipes of the second heat exchanger can both effectively dissipate heat.

[0012] As preferred, the surfaces of the radial flow paddles and the axial flow paddles of the paddle mechanism are coated with 30-50 μm low-surface-energy fluorine-containing polymers. Further, the fluorine-containing polymers can be selected from polytetrafluoroethylene or Teflon coatings, which have low surface energy and can reduce the adhesion between the paddle mechanism and the polymer, avoid overloading of the paddle mechanism due to excessive resistance of the stirred material, and promote stable flow of the stirred reaction solution to facilitate sufficient reaction.

[0013] Preferably, the roughness Ra of the outer surface of the inner wall of the cylinder of the reaction device and the outer wall of the heat exchange tube in contact with the reaction solution of the solution method is 0.2 μm. The key metal surfaces in contact with the polymer solution, such as the inner wall of the reactor cylinder and the outer wall of the internal column heat exchange tube, are precisely mechanically polished to control the surface roughness Ra at 0.2 μm. High polishing degree can significantly reduce the polymer wall hanging phenomenon.

[0014] The present application solves the problems of low mass transfer and heat transfer efficiency, uneven mixing, and local overheating of high viscosity solution polymer system; solves the problems of wall hanging, fouling, and poor discharge of high viscosity solution polymer system; solves the problems of large number of internal heat exchange components of the reactor, difficult structure design, and difficult internal cleaning of the reactor, and has the following beneficial effects: compensating for the thermal expansion difference caused by temperature change below 300℃, eliminating the temperature difference stress generated by the different thermal expansion coefficients of the tube bundle and the shell; maintaining the cleanliness of the inner wall of the reaction device and the outer wall of the first heat exchanger, avoiding incomplete reaction of the reactant monomer due to increased thermal resistance, and avoiding substandard products due to high residual monomer content; reducing the adhesion between the paddle mechanism and the polymer, avoiding overload of the paddle mechanism due to excessive resistance of the stirred material, and forming a stable flow field of the stirred reaction solution to promote full reaction. BRIEF DESCRIPTION OF DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are only exemplary, and those skilled in the art can also obtain other drawings according to the provided drawings without creative labor.

[0016] Figure 1 It is a schematic diagram of the external structure of a reaction device for preparing polyolefin by solution method.

[0017] Figure 2 It is a schematic diagram of the internal structure of a reaction device for preparing polyolefin by solution method.

[0018] Figure 3 It is an expanded view of the connection of the first heat exchanger.

[0019] Figure 4 It is a schematic diagram of the arrangement of the first heat exchanger and its inlet and outlet.

[0020] Figure 5 It is a pipe arrangement diagram of the heat exchange tube of the first heat exchanger.

[0021] Figure 6 It is a schematic diagram of the structure of the second heat exchanger.

[0022] Figure 7It is a local enlarged view of the second heat exchanger.

[0023] Figure 8 It is a schematic view of the connecting structure of the collection half-pipe and the vertical half-pipe.

[0024] Figure 9 It is a local enlarged view of the first discharge port.

[0025] Figure 10 It is a schematic view of the structure of the stirrer of Example 2.

[0026] Legend: 1 second heat exchanger; 11 spiral half-pipe; 12 collection half-pipe; 13 vertical half-pipe; 14 open surface; 15 closed surface; 2 first heat exchanger; 21 elbow; 22 heat exchange pipe; 3 stirrer; 31 axial flow paddle; 32 radial flow paddle; 4 first discharge port; 5 second discharge port; 6 barrel; 7 baffle pipe; 71 finger lever; 72 rotating nozzle. DETAILED DESCRIPTION

[0027] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments.

[0028] Example 1 In combination with Figure 1 and Figure 2 shown, a reaction device for preparing polyolefin by solution method includes a barrel 6 and a stirrer 3, the axis of the barrel 6 of the reaction device is provided with the stirrer 3, five groups of first heat exchangers 2 are arranged annularly inside the barrel 6 of the reaction device, the first heat exchanger 2 includes at least two vertical heat exchange pipes 22, the inlet and outlet of the first heat exchanger 2 are located at the bottom of the reaction device, the outer wall of the barrel 6 of the reaction device is attached with a second heat exchanger 1, a baffle pipe 7 is axially inserted into the gap between the first heat exchanger 2 and the inner wall of the barrel 6 of the reaction device, the baffle pipe 7 can destroy the flow boundary layer of the surface of the first heat exchanger 2 and the inner wall of the barrel 6 of the reaction device.

[0029] Through the above-mentioned arrangement, in combination with Figure 2 , Figure 3 , Figure 4 and Figure 5As shown, the reaction device is internally provided with five groups of first heat exchangers 2, the top of the heat exchange pipe 22 of the first heat exchanger 2 is connected by an elbow 21, the first heat exchanger 2 is a U-shaped pipe, one end of the U-shaped pipe bundle is fixed, and the other end is freely extendable, which can compensate for the thermal expansion difference caused by temperature change below 300°C, eliminate the temperature difference stress generated by the different thermal expansion coefficients of the pipe bundle and the shell, and solve the thermal compensation problem of the pipe bundle cooling system; the cooling medium in the first heat exchanger 2 is usually desalted water, the heat exchange pipe 22 adopts a high-flux pipe, and the surface of the heat exchange pipe 22 has a microporous structure or other structure for increasing the surface area for heat dissipation, which can greatly promote the boiling heat transfer of the solution outside the pipe. Each group of first heat exchangers 2 has one inlet pipe N1 and one outlet pipe N2, N1a corresponds to N2a, N1b corresponds to N2b, N1c corresponds to N2c, N1d corresponds to N2d, and N1e corresponds to N2e. The cooling medium enters the head through the inlet pipe and then uniformly enters the heat exchange pipe 22, and every two first heat exchangers 2 at the top are connected by an elbow 21. The first heat exchanger 2 is internally provided with 36 heat exchange pipes 22, and the central connecting lines of the heat exchange pipes 22 form an angle of 60°.

[0030] As shown in Figure 1 The outside of the reaction device is provided with a second heat exchanger 1, different circulating media are introduced into the second heat exchanger 1 according to different stages of the reaction, low-pressure steam is introduced to warm up the reaction device before and at the beginning of the reaction, and the reaction device reaches the reaction temperature faster. After the reaction is stable and after the reaction is completed, the circulating medium of the second heat exchanger 1 is desalted water, which is used in combination with the first heat exchanger 2 to remove heat from the reaction solution. The reaction device is cooled simultaneously inside and outside, which improves the heat transfer efficiency and ensures that there is no heat transfer dead angle at the bottom and top of the reaction device.

[0031] As shown in Figure 2As shown, the stirrer 3 comprises a vertical stirring rod and a paddle mechanism sleeved outside the stirring rod, the paddle mechanism comprises radial flow paddles 32 located at the end of the stirring rod and at the bottom of the reaction device, and two layers of axial flow paddles 31, rotation of the radial flow paddles 32 generates radial turbulent flow perpendicular to the stirring rod, and the axial flow paddles 31 are arranged in sequence along the extension direction of the stirring rod, rotation of the axial flow paddles 31 generates axial flow parallel to the stirring rod. The stirrer 3 is provided with multiple layers of stirring paddles from bottom to top, the bottom layer is the radial flow paddle 32 with large blades perpendicular to the stirring plane, for generating strong radial turbulent flow at the bottom of the reaction device to realize rapid and uniform mixing of the liquid catalyst and the reactant solution, and the layers above the bottom layer are the axial flow paddles 31 with an angle with the stirring plane or with curvature, the axial flow paddles 31 can push the polymer in the reaction device to flow upward as a whole along the axial direction, cooperating with the radial turbulent flow at the bottom to form a flow field covering the inside of the reaction device; 4-8 baffle pipes 7 are arranged between the first heat exchanger 2 and the inner wall of the cylinder body 6 of the reaction device, the outer wall of the baffle pipe 7 is arrayed with at least two finger-shaped rods 71, the baffle pipe 7 can destroy the flow boundary layer near the inner wall surface when rotating, avoid the formation of small adhesions on the surface, maintain the heat transfer effect of the cylinder body 6, and prevent the small adhesions from growing into scale, if the material adheres to the wall of the heat exchange pipe 22 and the inner wall of the reactor, as the thickness of the adhered material increases, the adhered material layer grows into scale, the thermal resistance formed by the adhered material layer becomes larger and larger, and wall hanging will cause a significant decrease in heat transfer efficiency, and the product of the reaction device is prone to be unqualified due to high residual monomer content. The residual monomer content refers to the content of residual reactant monomer.

[0032] The surfaces of the radial flow paddles 32 and the axial flow paddles 31 of the paddle mechanism are coated with 40 μm of fluorine-containing polymer with low surface energy. Further, the fluorine-containing polymer can be selected as polytetrafluoroethylene, which utilizes the property of low surface energy to reduce the adhesion between the paddle mechanism and the polymer, avoid overloading of the paddle mechanism due to excessive resistance of the stirred material, and promote stable flow of the flow field of the stirred reaction solution to facilitate sufficient reaction.

[0033] As Figure 2As shown, the barrel 6 is provided with two discharge ports N3 and N4, N3 is the first discharge port 4, N4 is the second discharge port 5, the first discharge port 4 is located in the middle of the barrel 6, and the second discharge port 5 is located at the top of the barrel 6. When the reactor is not full, the operator uses the first discharge port 4 provided on the side wall of the barrel 6 of the reactor to discharge. Compared with the traditional discharge port located at the bottom, the use of fluid kinetic energy and gravity can guide the smooth discharge of the product while reducing the back mixing phenomenon, that is, reducing the phenomenon that part of the fluid in the reactor flows upward under the action of the stirrer 3 and then flows backward on the cross section of the flow channel under the influence of fluid kinetic energy and gravity. When the material height is level with the first discharge port 4, the back mixing phenomenon almost does not occur. When the material height is slightly higher than the first discharge port 4, only the material above the first discharge port 4 part occurs back mixing phenomenon; further, when the reactor is full, the operator uses the second discharge port 5 provided at the top of the barrel 6 of the reactor to discharge. Compared with the traditional discharge port located at the bottom and the above-mentioned discharge port located on the side wall of the barrel 6, the second discharge port 5 is located at the top of the reactor, which can greatly reduce the back mixing phenomenon, make the reaction more sufficient and uniform, shorten the material residence time distribution, and improve the reaction efficiency.

[0034] In combination Figure 1 and Figure 2 As shown, the second heat exchanger 1 is matched with the paddle mechanism, and the flat surface of the radial flow paddle 32 and the axial flow paddle 31 in the paddle mechanism is provided with the collection half pipe 12. In the stirring process of the stirrer 3, the part of the paddle mechanism directly contacted with the reaction solution has higher heat due to stirring friction and heat generated by the paddle driving the reaction solution than other positions of the flow field. The collection half pipe 12 is arranged at the plane position to shorten the heat exchange path. Secondly, compared with the vertical half pipe 13, the open surface 14 of the collection half pipe 12 surrounds the annular surface of the plane position of the barrel 6 of the reactor, and there is a gap between adjacent vertical half pipes 13, but there is no discontinuity in the collection half pipe 12. Thirdly, although the axial flow paddle 31 mainly generates axial fluid, it actually also generates part of the radial fluid rotating in the same plane as the radial flow paddle 32, and the open surface 14 of the collection half pipe 12 can also better adapt to the horizontal flow field. In addition, through the above arrangement, the vertical half pipe 13 is connected with the collection half pipe 12 at both ends, and the vertical half pipe 13 can also correspondingly generate high-efficiency heat dissipation to the axial flow area generated by the axial flow paddle 31. The open surface 14 of the vertical half pipe 13 can better adapt to the axial flow field. The collection half pipe 12 and the vertical half pipe 13 of the second heat exchanger 1 can effectively dissipate heat.

[0035] In combination Figure 1 and Figure 8As shown in the drawings, the top and bottom of the cylinder body 6 are hemispherical, the middle part of the cylinder body 6 is cylindrical, the second heat exchanger 1 comprises a half-pipe structure, the half-pipe structure is a tubular structure cut along the extension direction, the open surface 14 of the half-pipe structure is a heat-conducting surface, and the closed surface 15 of the half-pipe structure is a heat-dissipating surface. The heat-conducting surface is attached to the outer wall of the cylinder body 6. The circulating medium inside the half-pipe structure exchanges heat with the reaction solution inside the cylinder body 6 through the heat-conducting surface. Since the heat-conducting surface of the half-pipe structure is the open surface 14 with a large heat-dissipating area, and the reaction solution is only separated from the cylinder body 6, the heat transfer efficiency of the half-pipe structure is high, and the heat transfer efficiency between the reaction solution is high.

[0036] In combination Figure 6 and Figure 7 As shown in the drawings, the half-pipe structure comprises a spiral half-pipe 11, a collection half-pipe 12, and vertical half-pipes 13 connected to the two ends of the collection half-pipe 12. The top and bottom of the cylinder body 6 are attached to the heat-conducting surface of the spiral half-pipe 11, and the middle part of the cylinder body 6 is attached to the heat-conducting surface of the collection half-pipe 12 and the vertical half-pipes 13. The half-pipe structure covers each surface of the cylinder body 6 of the reaction device, avoiding the heat transfer dead angle at the bottom and top of the cylinder body 6. The size of the collection half-pipe 12 is DN50~DN100, and the size of the vertical half-pipe 13 is DN25~DN50. In this embodiment, the sizes of the collection half-pipe 12 and the vertical half-pipe 13 are DN50 and DN25, respectively.

[0037] As shown in the drawings, Figure 2 and Figure 9 The outer wall of the baffle pipe 7 is provided with a finger-shaped rod 71, the included angle α between the finger-shaped rod 71 and the outer wall of the baffle pipe 7 is 15-90°, and the end of each finger-shaped rod 71 is provided with a rotating nozzle 72. In this embodiment, the included angle α between the finger-shaped rod 71 and the outer wall of the baffle pipe 7 is 45°. Through the above arrangement, the baffle pipe 7 can input a hot solvent which does not participate in the reaction but has a temperature close to the reaction temperature, and the hot solvent is sprayed out by the rotating nozzle 72. The finger-shaped rod 71 not only acts as a turbulence element, but also can cooperate with the hot solvent to perform purging, can form a sustained fluid shear force, and can clean the inner wall of the cylinder body 6 and the outer surface of the heat exchange pipe 22 of the first heat exchanger 2. The polymer in the reaction for producing polyolefin belongs to a high-viscosity system, and the system has poor fluidity, which is prone to problems such as wall sticking and pot sticking. The fluid shear force can peel off the material adhesion of the reaction on the inner wall of the cylinder body 6 and the outer surface of the heat exchange pipe 22 of the first heat exchanger 2, prevent the material adhesion from growing into scale, solve the problem that the thickness of the material adhesion increases after growing, the thermal resistance of the material adhesion layer also increases, and the heat transfer efficiency decreases, and the product residual monomer content is high and does not meet the standard. The hot solvent is separated from the reaction product through subsequent processes.

[0038] As shown in the drawings, Figure 9As shown, the centerline of the first discharge port 4 forms a downward angle β with the horizontal plane of 15-75°. In this embodiment, the angle β between the centerline of the first discharge port 4 and the horizontal plane is 30°. With the above configuration, this structure can fully utilize fluid kinetic energy and gravity to guide the product to discharge smoothly, effectively avoiding the accumulation and blockage of polymer in the outlet area.

[0039] The surface roughness Ra of the outer surfaces of the reactor cylinder 6 and the heat exchange tube 22 that come into contact with the reaction solution in the solution method is 0.2 μm. All key metal surfaces in contact with the polymer solution, such as the inner wall of the reactor cylinder 6 and the outer wall of the internal tube heat exchange tube 22, are precision mechanically polished to control the surface roughness Ra at 0.2 μm. The high polishing degree can significantly reduce polymer adhesion to the walls.

[0040] Example 2 like Figure 10 As shown, in this embodiment, unlike Embodiment 1, the stirring rod of the stirrer 3 is provided with finger-shaped rods 71. The finger-shaped rods 71 ​​form an angle with the outer wall of the stirring rod, causing the finger-shaped rods 71 ​​to rotate and generate a cone angle γ. The spatial projection of the finger-shaped rods 71 ​​covers the impeller mechanism below. The stirring rod of the stirrer 3 has a hollow structure, allowing the input of hot solvent that does not participate in the reaction but has a temperature close to the reaction temperature. Similar to Embodiment 1, the finger-shaped rods 71 ​​can output this hot solvent, which is sprayed out using a rotating nozzle 72. The finger-shaped rods 71 ​​not only cooperate with the hot solvent for purging but also form a continuous fluid shear force on the outer surface of the impeller mechanism. The polymers in the reaction producing polyolefins are high-viscosity systems with poor fluidity, easily leading to problems such as wall adhesion and vessel sticking. The fluid shear force can peel off the material adhering to the impeller mechanism, avoiding increased rotational load on the impeller mechanism and preventing the impeller gaps from being filled with material, thus reducing the stirring effect of the impeller mechanism.

[0041] In another embodiment, to avoid the influence of the finger rod 71 on the stirring rod and the hot solvent purging on the axial flow field generated by the stirring of the axial flow blade 31, the finger rod 71 is adjusted to an inclined nozzle on the stirring rod. The included angle of the inclined nozzle is the same as that of the finger rod 71 in Embodiment 2. The hot solvent sprayed from the inclined nozzle has a weaker purging effect on the blade mechanism than the finger rod 71. However, at a lower stirring speed, the inclined nozzle has a weaker influence on the axial flow field generated by the stirring of the axial flow blade 31, which is beneficial to the fluid flow inside the reaction device.

[0042] The present application solves the problems of low mass transfer and heat transfer efficiency, uneven mixing, local overheating of high viscosity solution polymer system; solves the problems of wall hanging, fouling, poor discharge of high viscosity solution polymer system; solves the problems of many heat exchange components in the reactor, difficult structure design, difficult cleaning of the reactor, and has the following beneficial effects: compensating for the thermal expansion difference caused by temperature change below 300 DEG C, eliminating the temperature difference stress generated by the different thermal expansion coefficients of the tube bundle and the shell; maintaining the cleanliness of the inner wall of the reaction device and the outer wall of the first heat exchanger 2, avoiding incomplete reaction of the reactant monomer due to the increase of thermal resistance, avoiding the product of the reaction device being out of standard due to the high residual monomer content; reducing the adhesion between the paddle mechanism and the polymer, avoiding the overload of the paddle mechanism due to the excessive resistance of the stirred material, and forming a stable flow field of the stirred reaction solution to promote sufficient reaction.

[0043] The above examples and / or embodiments are only used to illustrate the preferred examples and / or embodiments of the present application, and do not limit the embodiments of the present application in any form, and any person skilled in the art can make some changes without departing from the scope of the technical means disclosed in the present application, but still should be regarded as the same technology or embodiment as the present application.

Claims

1. A reaction apparatus for the solution polymerization of polyolefins comprising a cylinder (6) and a stirrer (3), characterized in that, The axis of the barrel (6) of the reaction device is provided with a stirrer (3), the inside of the barrel (6) of the reaction device is provided with at least two groups of first heat exchangers (2) in a ring shape, the first heat exchanger (2) comprises at least two vertical heat exchange pipes (22), the inlet and outlet of the first heat exchanger (2) are located at the bottom of the reaction device, the outer wall of the barrel (6) of the reaction device is attached with a second heat exchanger (1), the gap between the first heat exchanger (2) and the inner wall of the barrel (6) of the reaction device is axially inserted with a baffle tube (7), the baffle tube (7) can destroy the flow boundary layer of the surface of the first heat exchanger (2) and the barrel (6) of the reaction device.

2. A solution process for producing polyolefins according to claim 1, characterized in that, The top and bottom of the barrel (6) are hemispherical surfaces, the middle part of the barrel (6) is a cylindrical surface, the second heat exchanger (1) comprises a half-pipe structure, the half-pipe structure is a tubular structure cut along the extension direction, the open surface (14) of the half-pipe structure is a heat conduction surface, the closed surface (15) of the half-pipe structure is a heat dissipation surface, and the heat conduction surface is attached to the outer wall of the barrel (6).

3. A solution process for producing polyolefins according to claim 2, characterized in that, The half-pipe structure comprises a spiral half-pipe (11), a collection half-pipe (12), and vertical half-pipes (13) connected to the two ends of the collection half-pipe (12), the heat conduction surface of the spiral half-pipe (11) is attached to the top and bottom of the barrel (6), and the heat conduction surfaces of the collection half-pipe (12) and the vertical half-pipes (13) are attached to the middle part of the barrel (6).

4. The solution process for producing polyolefin according to claim 1, wherein, The outer wall of the baffle tube (7) is provided with a finger-shaped rod (71), the included angle between the finger-shaped rod (71) and the outer wall of the baffle tube (7) is 15-90°, and the end of each finger-shaped rod (71) is provided with a rotating nozzle (72).

5. The solution process for producing polyolefin according to claim 1, wherein, The barrel (6) is provided with at least two discharge ports, the discharge ports comprise a first discharge port (4) and a second discharge port (5), the first discharge port (4) is located in the middle part of the barrel (6), and the second discharge port (5) is located in the top of the barrel (6).

6. A solution process for producing polyolefins according to claim 5, characterized in that, The central line of the first discharge port (4) has an included angle of 15-75° downward with the horizontal plane.

7. A solution process for producing polyolefins as claimed in claim 3, wherein, The stirrer (3) comprises a vertical stirring rod and a paddle mechanism sleeved outside the stirring rod, the paddle mechanism comprises radial flow paddles (32) and at least one layer of axial flow paddles (31), the radial flow paddles (32) are located at the end of the stirring rod and at the bottom of the reaction device, the rotation of the radial flow paddles (32) generates radial turbulent flow perpendicular to the stirring rod, and the axial flow paddles (31) are arranged in sequence along the extension direction of the stirring rod.

8. A solution process for producing polyolefins according to claim 7, characterized in that, The second heat exchanger (1) is matched with the paddle mechanism, and the plane where the radial flow paddles (32) and the axial flow paddles (31) in the paddle mechanism are arranged is provided with the collection half-pipe (12).

9. A solution process for producing polyolefins according to claim 7, characterized in that, The surfaces of the radial flow paddles (32) and the axial flow paddles (31) of the paddle mechanism are coated with a low-surface-energy fluorine-containing polymer with a thickness of 30-50 μm.

10. The solution process for producing polyolefin according to claim 1, wherein, The roughness Ra of the outer surface of the inner wall of the barrel (6) of the reaction device and the outer wall of the heat exchange pipe (22) in contact with the reaction solution of the solution method is less than 0.2 μm.

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