Polymerization reactor and application thereof

Abstract

The invention belongs to the field of high-molecular polymerization reactors, and relates to a polymerization reactor and application thereof, the polymerization reactor comprises a cylinder, an upper seal head and a lower seal head; a flow guide device is arranged in the upper sealing head and is conical, and the tip of the conical flow guide device faces the central flow guide pipe. The conical flow guide device can evenly distribute materials flowing out of the center flow guide pipe, turbulent flow generated when the materials flow to the flow reducing pipe is reduced or even eliminated, the flow speed of the materials in the flow reducing pipe is increased, distribution is balanced, gluing on the pipe wall is greatly slowed down, heat accumulation in the center flow guide pipe is avoided, and production efficiency is improved.

Description

Technical Field

[0001] This invention belongs to the field of polymer polymerization reactors, and relates to a polymerization reactor and its application, specifically to a polymerization reactor for olefin cationic polymerization and its application in olefin cationic polymerization. Background Technology

[0002] Olefin cationic polymerization is one of the important industrial methods for preparing synthetic rubber. For example, isobutylene and a small amount of isoprene copolymerize to form butyl rubber, and butyl rubber combines with halogens to form halogenated butyl rubber. These are important synthetic rubber varieties and are the main raw materials for tire production.

[0003] Cationic polymerization is a vigorous reaction with a large amount of exothermic heat. During the reaction, it is crucial to remove the heat promptly and control the reaction temperature to obtain the desired polymer product. Industrial polymerization reactors for cationic polymerization are designed specifically for this purpose. A representative example is the butyl rubber reactor disclosed in patent document RU2097122. This reactor is a vertical tubular reactor with a multi-layered, multi-bladed agitator at the center. Multiple sets of tubular bundles are arranged inside the reactor, through which liquid ethylene is introduced, and the heat of polymerization is removed by the vaporization of the ethylene. Patent document US5417930 discloses an Exxon butyl rubber tubular reactor. The tube side is the polymerization reaction zone, while the shell side is circulated with a coolant to remove the reaction heat. The tube side consists of equal-diameter tubes divided into two zones: a central tube bundle as an ascending channel and peripheral tube bundles as descending channels. A propeller is located at the bottom of the reactor. The reactants enter the tubular reactor from the bottom and, after being propelled by the propeller, reach the top of the reactor from the central tube bundle. Most of the material then flows back to the bottom of the reactor from the peripheral tube bundles. A discharge pipe is provided at the top of the reactor. Patent document CN103608100 discloses an improved tubular reactor, which improves upon the tubular reactors disclosed in US2999084 and US5417930. The difference between CN1036080 and US5417930 is that the central tube bundle is replaced with a large-diameter single tube as the central guide tube. The reactants rise from the central guide tube. At the same time, in order to ensure the uniformity of the reaction liquid flow rate, guide devices are set at the upper and lower ends of the central guide tube.

[0004] However, existing reactors still suffer from uneven flow rates of reactants. Uneven flow rates lead to unbalanced reactions, resulting in polymer scaling on the reactor walls. This, in turn, affects the heat transfer efficiency of the refrigerant, preventing the timely removal of reaction heat and causing the reaction to become unsustainable, necessitating shutdown and cleaning – an industrial problem.

[0005] Therefore, it is still necessary to find a cationic polymerization reactor that can achieve a uniform flow rate of reactants, thereby extending the polymerization cycle. Summary of the Invention

[0006] This invention provides a polymerization reactor and its application, which has better thermal and hydraulic efficiency compared to traditional tubular reactors.

[0007] Specifically, the present invention provides a polymerization reactor, which includes a cylindrical body, an upper end cap, and a lower end cap, wherein the upper end cap is disposed at the top of the cylindrical body and the lower end cap is disposed at the bottom of the cylindrical body;

[0008] The cylinder is equipped with a tube array, which includes a central guide tube and a downflow tube. The central guide tube serves as an upward channel for the polymer material, catalyst, and polymer material returning from the downflow tube to mix and rise. The downflow tube is located around the central guide tube and is used to return part of the polymer material mixture to the bottom of the reactor.

[0009] The upper end cap is provided with a flow guiding device, which is conical with the tip of the cone facing the central flow guiding pipe.

[0010] According to an embodiment of the present invention, the downflow tubes are evenly distributed around the central guide tube.

[0011] According to an embodiment of the present invention, the central guide pipe is disposed in the middle of the cylinder.

[0012] According to an embodiment of the present invention, the central guide pipe is concentrically arranged with the cylinder.

[0013] According to an embodiment of the present invention, the flow guiding device is concentrically arranged with the central flow guiding pipe.

[0014] According to an embodiment of the present invention, the ratio of the bottom diameter of the flow guiding device to the diameter of the central flow guiding pipe is (0.2-2.0):1, preferably (0.5-1.5):1, for example 0.2:1, 0.4:1, 0.6:1, 0.8:1, 1.0:1, 1.2:1, 1.4:1, 1.6:1, 1.8:1, 2.0:1.

[0015] According to an embodiment of the present invention, the height ratio of the flow guiding device to the height of the upper end cap is (0.3-1.0):1, preferably (0.5-1.0):1, for example 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1 or 1.0:1.

[0016] According to an embodiment of the present invention, the upper part of the central guide tube extends into the upper end cap, and the ratio of the extended length to the height of the upper end cap is (0.1-0.8):1, for example, 0.1:1, 0.2:1, 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.7:1 or 0.8:1.

[0017] According to an embodiment of the present invention, the diameter of the extension portion of the central guide tube is greater than or equal to the diameter of the central guide tube. Preferably, the diameter of the extension portion of the central guide tube gradually increases, for example, the extension portion of the central guide tube may be trumpet-shaped.

[0018] According to an embodiment of the present invention, the cone tip of the flow guiding device is located on the upper outlet plane of the central flow guiding tube.

[0019] According to an embodiment of the present invention, a propeller is provided inside the central guide tube. The propeller is located in the lower middle part of the central guide tube and its function is to push the polymerization reaction raw materials at the bottom to flow upward.

[0020] According to an embodiment of the present invention, the propeller is disposed at the bottom of the central guide tube.

[0021] According to an embodiment of the present invention, the propeller is, for example, an impeller-type propeller, and the diameter of the propeller is smaller than the inner diameter of the central guide tube.

[0022] According to an embodiment of the present invention, the upper end cap is provided with a reactant outlet.

[0023] According to an embodiment of the present invention, the lower end cap is provided with a reactant inlet and a catalyst inlet.

[0024] According to an embodiment of the present invention, a refrigerant inlet is provided on the lower outer side of the cylinder, and a refrigerant outlet is provided on the upper outer side of the cylinder.

[0025] According to an embodiment of the present invention, the refrigerant is selected from one or more of methane, ethylene, and propylene.

[0026] Secondly, the present invention provides an application of the above-mentioned polymerization reactor in a polymerization reaction.

[0027] According to an embodiment of the present invention, the polymerization reaction is a cationic polymerization reaction, for example, an olefin cationic polymerization reaction.

[0028] According to an embodiment of the present invention, the polymerization reactor is used for olefin cationic polymerization reaction at -110°C to 0°C.

[0029] Beneficial effects

[0030] In the polymerization reactor of the present invention, a conical guide device is provided above the central guide pipe. The conical guide device can evenly divert the material flowing out of the central guide pipe, reduce or even eliminate the turbulence generated when the material flows towards the downflow pipe, thereby increasing the material flow velocity in the downflow pipe and making the distribution more even. This greatly reduces the adhesion of adhesive to the pipe wall, avoids the accumulation of heat in the central guide pipe, improves the heat and mass transfer effect of the reactor, and increases production efficiency. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the polymerization reactor in this invention.

[0032] The components are: 1. cylinder, 2. upper head, 3. lower head, 4. monomer inlet, 5. catalyst inlet, 6. reactant outlet, 7. refrigerant inlet, 8. refrigerant outlet, 9. guide cone, 10. propeller, 11. central guide tube, 12. downflow tube, and 13. tube sheet. Detailed Implementation

[0033] The structure of the present invention will be further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are merely illustrative and explanatory of the present invention and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are covered within the scope of protection intended by the present invention.

[0034] In the description of this invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0035] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0036] Example 1

[0037] See Figure 1As shown, a polymerization reactor includes a cylindrical body 1, with a series of tubes arranged inside the cylindrical body 1. An upper end cap 2 is provided at the top of the cylindrical body 1, and a lower end cap 3 is provided at the bottom of the cylindrical body 1. The tubes are fixed to the cylindrical body 1 via a tube sheet 13. The tubes include a central guide pipe 11 and a downflow pipe 12. The central guide pipe 11 is located in the middle of the cylindrical body 1, and the downflow pipe 12 is located around the central guide pipe 11. The central guide pipe 11 serves as an upward channel for the polymer material, catalyst, and polymer material returning from the downflow pipe after mixing. The downflow pipe 12, located around the central guide pipe 11, is used for partially returning the polymer material mixture to the bottom of the reactor. A propeller 10 is arranged inside the central guide pipe 11, located in the lower middle part of the central guide pipe 11, for example, at the bottom of the central guide pipe 11. The structure of the propeller 10 is selected according to actual needs, and its function is to push the reaction material at the bottom to flow upward. The propeller 10 is, for example, an impeller-type propeller, and the diameter of the propeller 10 is smaller than the inner diameter of the central guide pipe 11.

[0038] The upper part of the central guide tube 11 extends into the upper end cap 2, and the ratio of the length extending into the upper end cap 2 to the height of the upper end cap 2 is (0.1-0.8):1. The diameter of the extended part of the central guide tube 11 is greater than or equal to the diameter of the central guide tube 11. In this embodiment, the diameter of the extended part of the central guide tube 11 gradually increases, for example, in the shape of a trumpet.

[0039] Tube sheet 13 is set at the bottom of upper head 2 and the top of lower head 3, wherein the central guide pipe 11 is concentrically set with cylinder 1.

[0040] A flow guiding device 9 is provided on the inner top of the upper end cap 2. The flow guiding device 9 is conical, with the tip of the cone facing the central flow guiding pipe 11. The flow guiding device 9 and the central flow guiding pipe 11 are concentrically arranged, with the tip of the cone facing the center of the central flow guiding pipe 11. In this embodiment, the ratio of the bottom diameter of the flow guiding device 9 to the diameter of the central flow guiding pipe 11 is (0.2-2.0):1, and the ratio of the height of the flow guiding device 9 to the height of the upper end cap 1 is (0.3-1.0):1. Preferably, the cone tip of the flow guiding device is located on the upper outlet plane of the central flow guiding pipe 11.

[0041] The upper head 2 is provided with a reactant outlet 6, the lower head 3 is provided with a reactant inlet 4 and a catalyst inlet 5, the lower outer side of the cylinder 1 is provided with a refrigerant inlet 7, and the upper outer side of the cylinder 1 is provided with a refrigerant outlet 8.

[0042] The downflow pipes 12 are arranged in an array around the central guide pipe 11, for example, four concentric circles from the inside to the outside. The refrigerant inlet 7 introduces refrigerant into the shell side and contacts the outer wall of the central guide pipe 11 and the downflow pipe 12 to remove the heat of reaction. After the refrigerant is vaporized, it is discharged from the refrigerant outlet 8.

[0043] The refrigerant is selected from one or more of methane, ethylene, and propylene.

[0044] Example 2

[0045] The polymerization reactor from Example 1 was used for the production of butyl rubber with a Mooney degree of 55 at a rate of 3.3 t / h.

[0046] The downflow pipe 12 comprises four rows of pipes arranged concentrically with the central guide pipe 11 from the inside out (the rows are numbered sequentially from the central guide pipe 11 outwards as the first, second, third, and fourth rows). The upper end cap 2 and the lower end cap 3 are selected from standard semi-elliptical end caps. A conical guide device 9 is installed in the upper end cap 2. The ratio of the bottom diameter of the guide device 9 to the diameter of the central guide pipe 11 is 1.5, and the ratio of the height of the guide device 9 to the height of the upper end cap 1 is 0.5.

[0047] Butyl rubber is obtained by copolymerizing a mixture of isobutylene (greater than or equal to 95 wt%) and isoprene (not exceeding 5 wt%) with chloromethane as solvent to prepare a polymer material with a monomer concentration of 30-42 wt%. The copolymer is then copolymerized at -110℃ to -85℃ using dichloroethylaluminum as catalyst.

[0048] In this embodiment, the refrigerant is liquid ethylene, which is used to remove the heat of reaction by evaporation and vaporization, thereby controlling the reaction temperature.

[0049] This embodiment uses Fluent's commercial software to simulate the changes in material flow rate within the reactor.

[0050] The simulation results are as follows:

[0051] In the downflow pipe 12, the average flow velocity of the reactants is 3.14 m / s; among which,

[0052] The average flow velocity of the refrigerant in the first set of pipes is 2.86 m / s;

[0053] The average flow velocity of the refrigerant in the second set of pipes is 3.10 m / s;

[0054] The average flow velocity of the refrigerant in the third set of pipes is 3.08 m / s;

[0055] The average flow velocity of the refrigerant in the fourth column of pipes is 3.52 m / s.

[0056] The total pressure drop of the reactor (the pressure difference between the top and bottom of the reactants) is 22 kPa.

[0057] Comparative Example 1

[0058] The polymerization reactor used in this comparative example is identical to that in Example 2, except that it does not have the conical flow guide device 9.

[0059] This embodiment uses Fluent's commercial software to simulate the changes in material flow rate within the reactor.

[0060] The simulation results are as follows:

[0061] In the downflow pipe 12, the average flow velocity of the reactants is 2.92 m / s; among which,

[0062] The average flow velocity of the refrigerant in the first set of pipes is 2.25 m / s;

[0063] The average flow velocity of the refrigerant in the second set of pipes is 2.00 m / s;

[0064] The average flow velocity of the refrigerant in the third set of pipes is 2.85 m / s;

[0065] The average flow velocity of the refrigerant in the fourth column of pipes is 4.05 m / s.

[0066] The total pressure drop of the reactor is 29 kPa.

[0067] As can be seen from the comparative example, in the reactor, the material flow velocity in the downflow pipe 12 is uneven, and the flow velocity in the downflow pipe 12 near the central guide pipe 11 is low. The low flow velocity results in less cooling heat being carried away, which easily causes the butyl rubber particles generated in the reaction in the central guide pipe 11 to agglomerate and adhere to the inner wall of the central guide pipe 11. After the rubber adheres to the inner wall of the pipe, it forms a heat insulation layer, affecting the heat transfer and heat dissipation of the downflow pipe 12, resulting in heat accumulation in the central guide pipe 11 and causing reaction failure. In contrast, in the polymerization reactor of the present invention, the conical guide device 9 can evenly distribute the material flowing out of the central guide pipe, reduce or even eliminate the turbulence generated when the material flows to the downflow pipe, so that the material flow velocity in the downflow pipe 12 is faster and the distribution is more even, which greatly reduces the adhesion of rubber to the pipe wall, avoids heat accumulation in the central guide pipe 11, improves the heat and mass transfer effect of the reactor, and increases production efficiency.

[0068] The specific embodiments of the present invention have been described above by way of example. However, the scope of protection of the present invention is not limited to the above exemplary embodiments. Any modifications, equivalent substitutions, improvements, etc., made by those skilled in the art within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A polymerization reactor, the reactor comprising a cylindrical body, an upper end cap, and a lower end cap, the upper end cap being disposed at the top of the cylindrical body, and the lower end cap being disposed at the bottom of the cylindrical body; a series of tubes are disposed inside the cylindrical body, the series of tubes comprising a central guide tube and a downflow tube, the central guide tube serving as an upward channel for the polymer material, catalyst, and polymer material returning from the downflow tube after mixing, the downflow tube being disposed around the central guide tube for returning a portion of the polymer material mixture to the bottom of the reactor; characterized in that, The upper end cap is provided with a flow guiding device, which is conical in shape, with the tip of the cone facing the central flow guiding pipe.

2. The polymerization reactor according to claim 1, characterized in that, The downflow pipes are evenly distributed around the central guide pipe, which is located in the middle of the cylinder.

3. The polymerization reactor according to claim 1 or 2, characterized in that, The ratio of the bottom diameter of the flow guiding device to the diameter of the central flow guiding pipe is (0.2-2.0):

1.

4. The polymerization reactor according to any one of claims 1-3, characterized in that, The ratio of the height of the flow guiding device to the height of the upper end cap is (0.3-1.0):

1.

5. The polymerization reactor according to any one of claims 1-4, characterized in that, The upper part of the central guide tube extends into the upper end cap, and the ratio of its extension length to the height of the upper end cap is (0.1-0.8):

1.

6. The polymerization reactor according to any one of claims 1-5, characterized in that, The diameter of the extended portion of the central guide tube is larger than the diameter of the central guide tube.

7. The polymerization reactor according to any one of claims 1-6, characterized in that, The diameter of the extended portion of the central guide tube gradually increases.

8. The polymerization reactor according to any one of claims 1-7, characterized in that, The cone tip of the flow guiding device is located on the upper outlet plane of the central flow guiding pipe.

9. The polymerization reactor according to any one of claims 1-8, characterized in that, An actuator is installed inside the central guide tube. The actuator is located in the lower middle part of the central guide tube and its function is to push the polymerization reaction raw materials at the bottom to flow upward.

10. The use of the polymerization reactor according to any one of claims 1-9 in a polymerization reaction.

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