Reactor

Abstract

The invention belongs to the technical field of macromolecular polymerization reactors, and relates to a reactor, the reactor comprises a cylinder, an upper seal head and a lower seal head, the upper seal head is arranged at the top of the cylinder, and the lower seal head is arranged at the bottom of the cylinder; a tube nest is arranged inside the cylinder body, the tube nest comprises a central flow guide tube and a down-flow tube, the central flow guide tube is used as an ascending channel after a polymer material, a catalyst and a polymer material returned in the down-flow tube are mixed, and the down-flow tube is arranged on the periphery of the central flow guide tube and is used for returning part of the polymer material mixture to the bottom of the reactor; chamfer structures are arranged on the tops and / or the bottoms of at least part of the down-flow pipes. The chamfer structure can enlarge the liquid receiving area of the orifice of the downcomer, reduce the turbulent flow of the reaction material at the tube plate, and balance the flow velocity of the material in each downcomer.

Description

Technical Field

[0001] This invention belongs to the field of polymer polymerization reactor technology, and relates to a reactor, and more particularly to a polymer polymerization reactor. 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 tubular reactor disclosed in patent document US5417930 from Exxon. The tube side is the polymerization reaction zone, while the shell side is circulated with a coolant to remove the reaction heat. A propeller at the bottom of the reactor pushes the reactants upwards through the central tube. Upon reaching the upper head, most of the material flows back down through the surrounding tubes into the bottom head, where it mixes with fresh reactants and continues to flow upwards under the propeller's force. This cycle repeats, with some reactants being removed from the top of the reactor. However, the flow within the upper and lower heads is turbulent, resulting in uneven flow velocity and even dead zones. Patent document CN103608100 discloses an improved tubular reactor that increases the diameter of the central guide tube and incorporates flow guiding devices within the upper and lower heads, significantly improving the problem of uneven circulation velocity. Even so, the reactants still experience flow obstruction as they flow from the central guide tube to the downflow tube. Summary of the Invention

[0004] To overcome the shortcomings of the prior art, the present invention provides a reactor in which the connection between the tubes and the upper tube sheet and / or the lower tube sheet is provided with a chamfer structure. The chamfer structure can increase the liquid contact area of ​​the downcomer inlet, reduce the turbulence of the reactants at the tube sheet, and balance the flow rate of the materials in each downcomer.

[0005] Specifically, the present invention provides the following technical solution:

[0006] A reactor 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;

[0007] 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.

[0008] At least part of the downflow tube has a chamfered structure at the top and / or bottom.

[0009] According to an embodiment of the present invention, the top and / or bottom of the downflow pipe are provided with a chamfered structure.

[0010] According to an embodiment of the present invention, the chamfered structure is flared, with the flared opening facing the upper end cap or the lower end cap.

[0011] According to an embodiment of the present invention, the chamfered structure is disposed inside the upper end cap, at the connection between the upper tube sheet and the downflow pipe; and / or, the chamfered structure is disposed inside the lower end cap, at the connection between the lower tube sheet and the downflow pipe.

[0012] According to an embodiment of the present invention, the top of the chamfered structure is flush with the top of the upper tube sheet or the bottom of the lower tube sheet.

[0013] According to an embodiment of the present invention, the length 'a' of the chamfered structure refers to the length of the chamfered structure along the diameter direction of the downflow pipe, and the depth 'b' of the chamfered structure refers to the length of the chamfered structure along the length direction of the downflow pipe.

[0014] According to an embodiment of the present invention, the length 'a' of the chamfered structure corresponding to the downflow tube is half of the clearance distance between adjacent downflow tubes (pipe bridge, which refers to the distance between the edges of two downflow tubes in the straight line connecting the centers of two adjacent downflow tubes).

[0015] According to an embodiment of the present invention, when the downflow pipe is adjacent to one or more other downflow pipes, but there are multiple different pipe bridge values, the value of a is calculated as half of the minimum pipe bridge value.

[0016] According to an embodiment of the present invention, the depth b of the chamfered structure is 30-40% of the thickness of the corresponding upper tube sheet and / or lower tube sheet.

[0017] According to an embodiment of the present invention, a propeller is provided inside the central guide tube. Specifically, the propeller is located in the lower middle part of the central guide tube. The purpose of providing the propeller is to push the polymerization reaction raw materials at the bottom to flow upward.

[0018] According to an embodiment of the present invention, the propeller is disposed at the bottom of the central guide tube.

[0019] 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.

[0020] According to an embodiment of the present invention, the downflow tubes are evenly distributed around the central guide tube.

[0021] According to an embodiment of the present invention, the central guide pipe is disposed in the middle of the cylinder.

[0022] According to an embodiment of the present invention, the central guide pipe is concentrically arranged with the cylinder.

[0023] According to an embodiment of the present invention, the cylinder, the propeller, and the central guide tube are arranged concentrically.

[0024] According to an embodiment of the present invention, a flow guiding device is provided inside the upper end cap.

[0025] According to an embodiment of the present invention, a flow guiding device is provided inside the lower end cap.

[0026] According to an embodiment of the present invention, the flow guiding device, by changing the internal spatial structure of the head, guides the fluid in the reactor to circulate in the central flow guiding pipe and the downflow pipe, thereby reducing turbulence and balancing the flow velocity.

[0027] According to an embodiment of the present invention, the structure of the flow guiding device adopts a known flow guiding structure, such as the fluid transmission device in patent document CN103608100.

[0028] According to an embodiment of the present invention, the upper end cap is provided with a reactant outlet.

[0029] According to an embodiment of the present invention, the lower end cap is provided with a reactant inlet and a catalyst inlet.

[0030] 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.

[0031] According to an embodiment of the present invention, the refrigerant is selected from one or more of methane, ethylene, and propylene.

[0032] Secondly, the present invention provides an application of the above-mentioned polymerization reactor in a polymerization reaction.

[0033] According to an embodiment of the present invention, the polymerization reaction is a cationic polymerization reaction, for example, an olefin cationic polymerization reaction.

[0034] According to an embodiment of the present invention, the polymerization reactor is used for olefin cationic polymerization reaction at -110°C to 0°C.

[0035] The beneficial effects achieved by this invention are as follows:

[0036] This invention provides a reactor with a chamfered structure at the connection between the reactor tubes and the upper and / or lower tube sheet. The chamfered structure increases the liquid contact area at the downcomer inlets, reduces turbulence of the reactants at the tube sheet, and balances the flow velocity of the materials in each downcomer. This improves the reactor's hydraulic efficiency, reduces tube wall adhesion, and increases production efficiency. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the reactor structure in Embodiment 1 of the present invention.

[0038] Figure 2 This is a schematic diagram of the chamfered structure of the downflow tube at the upper tube sheet.

[0039] The components are: 1. cylinder, 2. upper head, 3. lower head, 4. reactant inlet, 5. catalyst inlet, 6. reactant outlet, 7. refrigerant inlet, 8. refrigerant outlet, 9. circulating propeller, 10. central guide pipe, 11. downflow pipe, 12. upper tube sheet, 13. lower tube sheet, 14. chamfered structure, a. width of chamfered structure, b. depth of chamfered structure. Detailed Implementation

[0040] 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.

[0041] 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.

[0042] 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.

[0043] Example 1

[0044] See Figure 1As shown, a reactor includes a cylindrical body 1, with tubes arranged inside the cylindrical body 1. The tubes include a central guide pipe 10 and a downcomer 11. 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 through an upper tube sheet 12 and a lower tube sheet 13. A chamfered structure 14 is provided at the connection between the downcomer 11 and the upper tube sheet 12 and the lower tube sheet 13.

[0045] The central guide pipe 10 is located in the middle of the cylinder 1. The propeller 9 is installed inside the central guide pipe 10. The propeller 9 is located in the lower middle part of the central guide pipe 10, for example, at the bottom of the central guide pipe 10. The structure of the propeller 10 is selected according to actual needs. Its function is to push the reaction material at the bottom to flow upward. The propeller 9 is, for example, an impeller-type propeller. The diameter of the propeller is smaller than the inner diameter of the central guide pipe 10.

[0046] The top and / or bottom of the downflow pipe 11 are provided with a chamfered structure 14, see [reference]. Figure 2 As shown, the chamfered structure 14 is horn-shaped with the horn-shaped opening facing the upper end cap 2 or the lower end cap 3. The chamfered structure 14 is disposed inside the upper end cap 2 or the lower end cap 3. At the connection between the upper tube sheet 12 and / or the lower tube sheet 13 and the downflow pipe 11, the top of the chamfered structure 14 is flush with the top of the upper tube sheet 12 or the bottom of the lower tube sheet 13.

[0047] Wherein, the length 'a' of the chamfered structure 14 refers to the length of the chamfered structure 14 along the diameter direction of the downflow pipe 11, and the depth 'b' of the chamfered structure refers to the length of the chamfered structure 14 along the length direction of the downflow pipe 11.

[0048] In this embodiment, the length a of the chamfered structure 11 corresponding to the middle downflow pipe 11 is half of the clearance distance (pipe bridge) between two adjacent downflow pipes 11; when the downflow pipe 11 is adjacent to one or more other downflow pipes 11, if there are multiple different pipe bridge values, the value a is calculated as half of the smallest pipe bridge value.

[0049] The depth b of the chamfered structure 14 is 30-40% of the thickness of the corresponding upper tube sheet 12 and / or lower tube sheet 13.

[0050] 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. The downflow pipes 11 are arranged in an array around the periphery of the central guide pipe 10, for example, four concentric rows of refrigerant inlets 7 from the inside to the outside to introduce refrigerant into the shell side and contact the outer walls of the central guide pipe 10 and the downflow pipes 11 to remove the heat of reaction. After the refrigerant is vaporized, it is discharged from the refrigerant outlet 8.

[0051] The reactor in this embodiment is also equipped with a flow guiding device. The structure of the flow guiding device is the same as that of the fluid transmission device 15 in patent document CN103608100. It is used to guide the fluid to flow along its curve to reduce vortex and turbulence dissipation and obtain better performance.

[0052] The refrigerant is selected from one or more of methane, ethylene, and propylene.

[0053] Example 2

[0054] The 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.

[0055] The downflow pipe 11 comprises four rows of pipes arranged concentrically with the central guide pipe 10 from the inside out (the rows are numbered sequentially from the central guide pipe 10 to the outside). The upper end cap 2 and the lower end cap 3 are selected from standard semi-elliptical end caps. The tube sheet thickness is 130 mm, the pipe bridge distance is 86 mm, and the chamfer width 'a' at the top and bottom of the downflow pipe is 43 mm, while the chamfer depth 'b' is 50 mm.

[0056] Butyl rubber is obtained by copolymerizing a mixture of isobutylene (greater than or equal to 95 wt%) and isoprene (no more than 5 wt%) with chloromethane as solvent, and using dichloroethylaluminum as catalyst at -110℃ to -85℃.

[0057] 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.

[0058] This embodiment uses Fluent's commercial software to simulate the changes in material flow rate within the reactor.

[0059] The simulation results are as follows:

[0060] In the downflow pipe 11, the average flow velocity of the reactants is 3.34 m / s; among which,

[0061] The average flow velocity of the reactants in the first pipeline is 3.28 m / s;

[0062] The average flow velocity of the reactants in the second pipeline is 3.35 m / s;

[0063] The average flow velocity of the reactants in the third pipeline is 3.34 m / s;

[0064] The average flow velocity of the reactants in the fourth pipeline is 3.40 m / s.

[0065] The total pressure drop of the reactor is 17 kPa.

[0066] Comparative Example 1

[0067] The reactor used in this comparative example is identical to that in Example 1 except for the absence of the chamfered structure 14, and the reaction conditions are identical to those in Example 2.

[0068] This embodiment uses Fluent's commercial software to simulate the changes in material flow rate within the reactor.

[0069] The simulation results are as follows:

[0070] In the downflow pipe 11, the average flow velocity of the reactants is 3.33 m / s; among which,

[0071] The average flow velocity of the reactants in the first pipeline is 3.23 m / s;

[0072] The average flow velocity of the reactants in the second pipeline is 3.30 m / s;

[0073] The average flow velocity of the reactants in the third pipeline is 3.32 m / s;

[0074] The average flow velocity of the reactants in the fourth pipeline is 3.47 m / s.

[0075] The total pressure drop of the reactor is 21 kPa.

[0076] The comparative examples show that the use of a chamfered structure improves the material flow rate in the tube and reduces the total pressure drop of the reactor.

[0077] 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 reactor, characterized in that, The reactor includes a cylindrical body, an upper end cap, and a lower end cap, with the upper end cap disposed at the top of the cylindrical body and the lower end cap disposed at the bottom of the cylindrical body; 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. At least part of the downflow tube has a chamfered structure at the top and / or bottom.

2. The reactor according to claim 1, characterized in that, The chamfered structure is trumpet-shaped, with the trumpet-shaped opening facing the upper or lower end cap.

3. The reactor according to claim 1 or 2, characterized in that, The chamfered structure is disposed inside the upper head, at the connection between the upper tube sheet and the downflow pipe; and / or, the chamfered structure is disposed inside the lower head, at the connection between the lower tube sheet and the downflow pipe; Preferably, the top of the chamfered structure is flush with the top of the upper tube sheet or the bottom of the lower tube sheet.

4. The reactor according to any one of claims 1-3, characterized in that, The length 'a' of the chamfered structure corresponding to the downflow tube is half the clearance distance between adjacent downflow tubes; Preferably, when the downflow pipe is adjacent to one or more other downflow pipes, but there are multiple different pipe bridge values, the value of a is calculated as half of the smallest pipe bridge value.

5. The reactor according to any one of claims 1-4, characterized in that, The depth b of the chamfered structure is 30-40% of the thickness of the corresponding upper tube sheet and / or lower tube sheet.

6. The reactor according to any one of claims 1-5, characterized in that, The central guide tube is equipped with a propeller.

7. The reactor according to any one of claims 1-6, characterized in that, The upper and / or lower end caps contain flow guiding devices.

8. The application of the polymerization reactor according to any one of claims 1-7 in a polymerization reaction.

9. The application according to claim 8, characterized in that, The polymerization reaction is a cationic polymerization reaction, such as an olefin cationic polymerization reaction.

10. The application according to claim 9, characterized in that, The polymerization reactor is used for olefin cationic polymerization reactions at -110℃ to 0℃.

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