Reaction kettle for producing ultra-high molecular weight polyethylene through ethylene polymerization

Abstract

The utility model provides a reaction kettle for producing ultra-high molecular weight polyethylene through ethylene polymerization, and belongs to the technical field of chemical production equipment. The reaction kettle comprises a kettle body, a stirring shaft is arranged in the kettle body, a stirring paddle is horizontally arranged on the stirring shaft, and the stirring paddle is positioned at the middle lower end of the stirring shaft; a liquid separation net is horizontally arranged at the upper part of the stirring shaft; eight ethylene / recycle gas feeding pipes are arranged in the kettle body, during continuous operation, 5-7 ethylene / recycle gas feeding pipes are used for feeding mixed gas of ethylene and recycle gas, meanwhile, 1-3 ethylene / recycle gas feeding pipes are used for feeding liquid, and switching is carried out. A condensate inlet pipe and a discharge pipe are arranged at the top of the kettle body; and a catalyst inlet pipe and a circulating gas outlet pipe are arranged on the kettle body. The reaction kettle provided by the utility model is used for producing ultra-high molecular weight polyethylene through ethylene polymerization, has better gas-liquid mixing capacity, improves the reaction efficiency, and solves the problems that the reaction kettle is easy to stick, hang and cake, an ethylene / recycle gas injection pipeline is blocked and the like when the ultra-high molecular weight polyethylene is produced.

Description

TECHNICAL FIELD

[0001] The utility model belongs to the technical field of chemical production equipment, and particularly relates to a reaction kettle for ethylene polymerization production of ultrahigh molecular weight polyethylene. BACKGROUND

[0002] In the production process of ethylene polymerization production of ultrahigh molecular weight polyethylene and other chemical products, a reaction kettle needs to be used for polymerization reaction, and such a polymerization reaction kettle needs to have strong mass transfer / heat transfer capacity and good dispersion capacity. In the process of ethylene oligomerization or polymerization, raw material ethylene is generally added to the reactor in gaseous form, and is generally fed in the form of kettle bottom feeding or reaction kettle inserted pipe. However, when ethylene is polymerized to produce ultrahigh molecular weight polyethylene, it is found that the reaction kettle is prone to problems such as sticking, material hanging, and ethylene / circulating gas injection pipeline blockage.

[0003] Research has found that the reasons for the problems of reaction kettle sticking, material hanging, and ethylene / circulating gas injection pipeline blockage mainly include the following aspects: ① poor mass transfer / heat transfer capacity of the reaction kettle, and low material backmixing efficiency in the reaction kettle; ② low ethylene / circulating gas feeding rate, which is prone to polymerization and blockage at the gas-liquid contact surface; and ③ local hot spots on the surface of polymer particles in the reaction kettle due to low heat transfer efficiency, which causes sticking and caking.

[0004] In order to improve the reaction rate and strengthen the mass transfer / heat transfer capacity of the reaction kettle, stirring equipment is usually used in the reaction kettle for stirring work. However, the circulation speed of the edge of such a reaction kettle is still slow, the gas-liquid mixing capacity is poor, and the problems of uneven mass transfer / heat transfer of the reaction kettle, easy blockage, and sticking of the reaction kettle are difficult to solve.

[0005] UTILITY MODEL

[0006] The utility model provides a kind of reaction kettle for ethylene polymerization production of ultrahigh molecular weight polyethylene, can be suitable for the heat exchange of cold medium or hot medium, and have better gas-liquid mixing capacity, improve the reaction efficiency of reaction kettle, solve the problems such as sticking, material hanging, caking and ethylene / circulating gas injection pipeline blockage of reaction kettle when producing ultrahigh molecular weight polyethylene.

[0007] The utility model provides a kind of reaction kettle for ethylene polymerization production of ultrahigh molecular weight polyethylene, including kettle body,

[0008] Stirring shaft is equipped in kettle body, and the top of stirring shaft is connected with motor by penetrating kettle body, and stirring paddle is horizontally equipped on stirring shaft, and stirring paddle is located in the middle and lower end of stirring shaft;The upper portion of stirring shaft is horizontally equipped with liquid distribution net, and liquid distribution net is located in kettle body;

[0009] The kettle body is provided with eight ethylene / cycle gas feeding pipes, when continuously operating, five to seven ethylene / cycle gas feeding pipes are used for feeding mixed gas of ethylene and cycle gas, and one to three ethylene / cycle gas feeding pipes are used for feeding liquid, and switching is carried out; the inner wall of the kettle body is provided with at least one support for supporting the eight ethylene / cycle gas feeding pipes;

[0010] The top of the kettle body is provided with a condensate inlet pipe and an adjustable plug-in outlet pipe; the bottom of the kettle body is provided with a mother liquor inlet pipe; the kettle body is further provided with a catalyst inlet pipe and at least one cycle gas outlet pipe; the outer side of the kettle body is provided with a jacket for heating or cooling medium.

[0011] Further, the liquid includes at least one of mother liquor, condensate or solvent.

[0012] Further, the stirring shaft and the kettle body are connected through a bearing; the stirring shaft is connected with the motor through a shaft coupling;

[0013] Preferably, the stirring shaft is uniformly provided with at least one layer of stirring paddles from bottom to top;

[0014] Preferably, the stirring shaft is uniformly provided with three layers of stirring paddles from bottom to top, which are respectively a layer of stirring paddles, a layer of stirring paddles and a layer of stirring paddles;

[0015] More preferably, each layer of stirring paddles includes at least one radial flow stirring blade and at least one axial flow stirring blade;

[0016] More preferably, the radial flow stirring blade is fixedly connected with the stirring shaft; the axial flow stirring blade is fixedly arranged at the lower part of the radial flow stirring blade.

[0017] Further, the liquid distribution net is formed by stacking multiple layers of screens;

[0018] The liquid distribution net is located above the stirring paddles, and the condensate inlet pipe is located above the liquid distribution net.

[0019] Further, the outlets of the eight ethylene / cycle gas feeding pipes are located between a layer of stirring paddles and a layer of stirring paddles.

[0020] Further, the number of supports for supporting the eight ethylene / cycle gas feeding pipes is three;

[0021] Preferably, the inner wall of the kettle body is fixedly provided with a layer of supports, a layer of supports and a layer of supports for supporting the eight ethylene / cycle gas feeding pipes from bottom to top;

[0022] More preferably, the supports are square corner structures.

[0023] Further, the jacket is wrapped on the outer side of the middle and lower kettle body.

[0024] The jacket is provided with a jacket water inlet and a jacket water outlet, the jacket water inlet is located at the bottom of the jacket, and the jacket water outlet is located at the upper portion of the jacket.

[0025] Further, the kettle body is provided with two circulating gas outlet pipes, which are located at the top and lower portion of the kettle body respectively.

[0026] Preferably, the outlet of the circulating gas outlet pipe is provided with an expansion section.

[0027] Preferably, the circulating gas outlet pipe is provided with an online condensate flushing function, which is realized by controlling the on-off valve on the circulating gas outlet pipe or the pipeline connected thereto.

[0028] Preferably, the outlet pipe is provided with an online solvent flushing function, which is realized by controlling the on-off valve on the outlet pipe or the pipeline connected thereto.

[0029] Further, the kettle body is provided with at least one remote temperature meter.

[0030] The top of the kettle body is provided with a remote pressure gauge.

[0031] The kettle body is provided with at least one remote liquid level meter.

[0032] Further, the catalyst inlet pipe is located at the lower portion of the kettle body.

[0033] The top of the kettle body is further provided with an emergency discharge pipe, and the emergency discharge pipe is provided with a safety valve interface; the bottom of the kettle body is provided with a kettle bottom discharge pipe.

[0034] The outer side of the kettle body is provided with a manhole; the manhole is located at the middle position of the kettle body.

[0035] The kettle body has the following beneficial effects:

[0036] 1. Eight ethylene / circulating gas inlet pipes can realize the switching of gas and liquid medium. When continuously running, five to seven inlet pipes are used to input ethylene / circulating gas, and one to three inlet pipes are used to input liquid (mother liquor, condensate or solvent), so as to realize the online flushing of the ethylene / circulating gas inlet pipe, and to play a role in forced back mixing and preventing polymer blockage.

[0037] 2. The reaction kettle is provided with a liquid distribution net, which can effectively prevent the problem of blockage of downstream heat exchangers, pipelines and the like caused by the entrainment of ultra-high molecular weight polyethylene powder when the circulating gas evaporates in the reaction kettle. The liquid distribution net is installed on the upper portion of the stirring shaft in the kettle, and when the stirring shaft rotates, the condensate injected into the reaction kettle can be centrifugally dispersed in the kettle, so as to avoid the problem of sudden temperature drop caused by the addition of condensate to the local portion of the kettle.

[0038] 3. The reaction kettle is externally provided with a jacket for heating or cooling medium, which makes the reaction kettle flexible and convenient when switching cold / heat medium, and can heat or cool the reaction kettle. The reaction kettle is provided with a gas phase circulating gas outlet pipe and a condensate inlet pipe, which can effectively control the temperature of the reaction kettle and solve the problem of heat removal of the reaction kettle. BRIEF DESCRIPTION OF DRAWINGS

[0039] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the drawings needed in the following embodiment or prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0040] Figure 1 The structure diagram of the device according to the embodiment of the present application is shown in the figure.

[0041] Explanation of reference signs:

[0042] Kettle body 100, ethylene / circulating gas feeding pipe 101, support 102, condensate inlet pipe 103, discharge pipe 104, mother liquor inlet pipe 105, circulating gas outlet pipe 106, catalyst inlet pipe 107, remote thermometer 108, remote pressure gauge 109, remote liquid level meter 110, emergency discharge pipe 111, kettle bottom discharge pipe 112, manhole 113, jacket 120, jacket water inlet 121, jacket water outlet 122, stirring shaft 200, stirring paddle 210, radial flow stirring blade 211, axial flow stirring blade 212, liquid distribution net 220, motor 300. DETAILED DESCRIPTION

[0043] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. The embodiments in the present application and the features in the embodiments can be combined with each other in the case of no conflict. In the description of the present application, it should be understood that the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only used for the purpose of facilitating the description of the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. The terms "first", "second" and the like are only used for description purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features limited by "first", "second" and the like can explicitly or implicitly include one or more of the features. The terms "mounting", "connecting", "connection" should be understood broadly, for example, can be fixed connection, can also be detachable connection, or integral connection; can be mechanical connection, can also be electrical connection; can be directly connected, can also be indirectly connected through an intermediate medium, can be the communication between two elements inside. When an element is referred to as "provided on" another element, it can be directly on the other element or there can be a middle element. The specific meanings of the above terms in the present application can be understood by the person skilled in the art according to the specific circumstances.

[0044] The present application will be described in detail below with reference to the drawings.

[0045] Referring to Figure 1 As shown in the drawings, the utility model proposes a kind of reaction kettle for ethylene polymerization production ultrahigh molecular weight polyethylene, including kettle body 100,

[0046] Stirring shaft 200 is equipped in kettle body 100, the top of stirring shaft 200 is connected with motor 300 by being worn out kettle body 100, stirring paddle 210 is horizontally equipped on stirring shaft 200, and stirring paddle 210 is located in the middle lower end of stirring shaft 200;The upper portion of stirring shaft 200 is horizontally equipped with liquid distribution net 220, and liquid distribution net 220 is located in kettle body 100;

[0047] 8 ethylene / cycle gas feed pipes 101 are equipped in kettle body 100, when continuously operating, 5-7 ethylene / cycle gas feed pipes 101 are used to enter the mixed gas of ethylene, cycle gas, while 1-3 ethylene / cycle gas feed pipes 101 are used to enter liquid, switching is carried out;At least one support 102 for supporting 8 ethylene / cycle gas feed pipes 101 is equipped on the inner wall of kettle body 100;

[0048] The top of the kettle body 100 is provided with a condensed liquid inlet pipe 103, an adjustable insertion depth insertion type discharge pipe 104; the bottom of the kettle body is provided with a mother liquor inlet pipe 105; the kettle body 100 is further provided with a catalyst inlet pipe 107, at least one circulating gas outlet pipe 106; the outer side of the kettle body 100 is provided with a jacket 120 for heating or cooling medium.

[0049] Further, the liquid includes at least one of the mother liquor, the condensed liquid or the solvent.

[0050] It should be pointed out that the mother liquor is the liquid obtained after the reaction material leaves the reaction kettle, and the polymer particles are removed by flash evaporation, centrifugal separation and other processes. The main components of the mother liquor include solvent and a small amount of alkyl aluminum.

[0051] The condensed liquid is the liquid obtained by condensing the gas phase in the reaction kettle through the kettle external heat exchanger. The main components of the condensed liquid include the solvent of the reaction.

[0052] The solvent is the solvent required for the reaction.

[0053] Further, the stirring shaft 200 and the kettle body 100 are connected through bearings; the stirring shaft 200 is connected with the motor 300 through a shaft coupling.

[0054] Further, the stirring shaft 200 is uniformly provided with at least one layer of stirring paddles 210 from bottom to top. Preferably, the stirring shaft 200 is uniformly provided with three layers of stirring paddles 210 from bottom to top, which are a layer of stirring paddles, a second layer of stirring paddles and a third layer of stirring paddles.

[0055] Further, each layer of stirring paddles 210 includes at least one radial flow stirring blade 211 and at least one axial flow stirring blade 212.

[0056] Further, the radial flow stirring blade 211 is fixedly connected with the stirring shaft 200; the axial flow stirring blade 212 is fixedly arranged at the lower portion of the radial flow stirring blade 211.

[0057] In the utility model, three layers of propelling type stirring paddles are arranged in the reaction kettle, the rotation of the stirring blades brings the material to stir, so that the material is continuously mixed in the stirring process, and the purpose of uniform mixing is achieved. The three groups of stirring blades can rotate in different directions to form three-dimensional stirring, so that the stirring effect is better.

[0058] Further, the liquid distribution net 220 is formed by stacking multiple layers of screen meshes. In the utility model, the liquid distribution net can effectively prevent the problem of blockage of downstream heat exchangers, pipelines and the like caused by entrainment of ultra-high molecular weight polyethylene powder when the circulating gas in the reaction kettle evaporates.

[0059] Further, the liquid distribution net 220 is located above the stirring paddle 210, and the condensate inlet pipe 103 is located above the liquid distribution net 220. In the utility model, the liquid distribution net is installed on the upper portion of the stirring shaft in the kettle, and when the stirring is rotated, the condensate injected into the reaction kettle can be centrifugally dispersed into the kettle body, so that the problem that the condensate is added into the kettle to cause a sudden temperature drop in the local portion can be avoided.

[0060] In the utility model, the reaction kettle ethylene / circulating gas feed pipe is provided with 8 roots, and the switching of gas and liquid medium can be realized. Preferably, when continuously operating, 5-7 roots of the feed pipe simultaneously feed ethylene / circulating gas, and 1-3 roots of the feed pipe feed liquid.

[0061] When continuously operating, 5-7 roots of the ethylene / circulating gas feed pipe 101 are used for feeding the mixed gas of ethylene and circulating gas, and simultaneously 1-3 roots of the ethylene / circulating gas feed pipe are used for feeding liquid, and the switching is carried out. For example, when continuously operating, 5 roots of the ethylene / circulating gas feed pipe 101 are used for feeding the mixed gas of ethylene and circulating gas, and simultaneously 3 roots of the ethylene / circulating gas feed pipe are used for feeding liquid, and after a period of time, the other 3 roots of the ethylene / circulating gas feed pipe are used for feeding liquid, and the remaining 5 roots are used for feeding the mixed gas of ethylene and circulating gas, and the switching is carried out, so that the ethylene / circulating gas feed pipe can realize online flushing, and further prevent the polymer from blocking the ethylene / circulating gas feed pipe.

[0062] Specifically, the pipeline connected with each ethylene / circulating gas feed pipe 101 is provided with a pipeline for conveying gas (ethylene / circulating gas), mother liquor, condensate or solvent, and the pipeline is provided with a switch valve, so that the online switching is realized.

[0063] Further, the outlets of the 8 ethylene / circulating gas feed pipes 101 are located between the first layer of stirring paddles and the second layer of stirring paddles. The position has the strongest back mixing area.

[0064] Further, the number of the supports for supporting the 8 ethylene / circulating gas feed pipes 101 can be 1, 2, 3, 4, 5, 6, 7, 8 or 9. Preferably, the number of the supports for supporting the 8 ethylene / circulating gas feed pipes is 3. More preferably, the inner wall of the kettle body 100 is fixedly provided with a first layer of supports, a second layer of supports and a third layer of supports from bottom to top for supporting the 8 ethylene / circulating gas feed pipes 101. In the utility model, the reaction kettle ethylene / circulating gas feed pipe is provided with 8 roots, and the multiple layers of supports are used to fix the ethylene / circulating gas feed pipe, so that the supports can play the role of baffle and can forcibly mix the materials in the kettle.

[0065] Further, the support 102 is a square round corner structure. The support 102 can increase the impact of gas-liquid two-phase materials and reduce stress concentration.

[0066] Further, the jacket 120 is wrapped on the outer side of the middle and lower kettle body.

[0067] Further, the jacket 120 is provided with a jacket water inlet 121 and a jacket water outlet 122, the jacket water inlet 121 is located at the bottom of the jacket 120, and the jacket water outlet 122 is located at the upper part of the jacket 120. In the utility model, the heat removal mode of the reaction kettle mainly has a reaction kettle jacket. Preferably, the gas phase evaporation latent heat of the material in the kettle is utilized, the gas phase circulation of the components in the kettle is circulated to the kettle external condenser for condensation, the obtained condensate is returned to the reaction kettle, the evaporation latent heat of the gas phase in the kettle reaches the purpose of high-efficiency heat removal, the problems of low heat removal efficiency of the conventional kettle coil and blockage, wall hanging and other problems caused by the external circulation of the liquid phase suspended material in the kettle are solved.

[0068] Further, the kettle body is provided with two circulating gas outlet pipes 106, which are located at the top and lower part of the kettle body 100.

[0069] Further, the outlet of the circulating gas outlet pipe 106 has an expansion section. The outlet is provided with an expansion section, which can effectively settle the ultra-high molecular weight polyethylene powder.

[0070] Preferably, the circulating gas outlet pipe has an online condensate flushing function, and the function is realized by controlling the on-off valve on the circulating gas outlet pipe or the connected pipeline. The problem that the ultra-high molecular weight polyethylene powder in the reaction kettle is entrained by the circulating gas to cause the blockage of the downstream heat exchanger and pipeline can be prevented.

[0071] In the utility model, the insertion type discharge pipe 104 with adjustable insertion depth can adjust the depth of insertion into the reaction kettle. Preferably, the discharge pipe 104 has an online solvent flushing function, and the function is realized by controlling the on-off valve on the discharge pipe 104 or the connected pipeline. The concentration distribution of the material in the reaction kettle can be effectively adjusted, and the blockage problem of the discharge pipeline can be solved.

[0072] Further, the catalyst inlet pipe 107 is located at the lower part of the kettle body.

[0073] Further, the top of the kettle body 100 is also provided with an emergency discharge pipe 111, and the emergency discharge pipe 111 is provided with a safety valve interface; the bottom of the kettle body 100 is provided with a kettle bottom discharge pipe 112.

[0074] Further, the outer side of the kettle body 100 is provided with a manhole 113; the manhole 113 is located at the middle position of the kettle body 100.

[0075] Further, at least one remote thermometer 108 is arranged on the kettle body 100. Preferably, at least four remote thermometers 108 are arranged on the kettle body 100, and the remote thermometers 108 are respectively located at the lower part, the middle-lower part, the circulating gas outlet pipe 106 (not shown) and the emergency discharge pipe 111 (not shown) of the kettle body 100.

[0076] Further, the top of the kettle body 100 is provided with a remote pressure gauge 109.

[0077] Further, the kettle body 100 is provided with at least one remote liquid level gauge 110. Preferably, two remote liquid level gauges 110 are provided in the kettle body 100, which are respectively located in the lower part and the middle-lower part of the kettle body 100.

[0078] Further, the kettle body 100 is in the shape of a cylinder, and the longitudinal section of the bottom of the cylinder is in the shape of a circular arc. Herein, the axial direction of the stirring shaft is the longitudinal direction, and the radial direction is the transverse direction.

[0079] Further, the inner wall of the kettle body 100 and all the internal parts in the kettle body 100 are polished. After polishing, the sticking and hanging of the polymer materials on the inner wall of the kettle body can be effectively prevented. More preferably, the polishing of the inside of the kettle body reaches 0.4 μm, and preferably 0.2 μm.

[0080] The specific implementation process is as follows:

[0081] The raw material ethylene is mixed with the circulating gas and injected into the reaction kettle through 5-7 ethylene / circulating gas feeding pipes 101 between the bottom stirring paddle and the second stirring paddle. The catalyst is introduced into the reaction kettle through the catalyst inlet pipe 107, and the solvent is introduced into the reaction kettle through 1-3 ethylene / circulating gas feeding pipes 101. The motor 300 is started to drive the stirring shaft 200 and the stirring paddle 210 to rotate. After the polymerization reaction, the reaction product flows out through the discharge pipe 104, and the obtained mother liquor (the liquid obtained after the polymer particles are removed from the reaction product leaving the discharge pipe 104 through flash evaporation, centrifugal separation and other processes) enters the reaction kettle from the mother liquor inlet pipe 105 at the bottom of the reaction kettle or is injected from 1-3 ethylene / circulating gas feeding pipes 101. That is, 5-7 ethylene / circulating gas feeding pipes 101 are used for the mixed gas of ethylene and circulating gas to enter, and 1-3 ethylene / circulating gas feeding pipes 101 are used for the liquid such as mother liquor or solvent to enter. After a period of time, 1-3 ethylene / circulating gas feeding pipes are selected for the liquid such as mother liquor or solvent to enter, and the remaining 5-7 ethylene / circulating gas feeding pipes are used for the mixed gas of ethylene and circulating gas to enter. The switching is carried out in this way, so that the ethylene / circulating gas feeding pipes can be online washed, thereby preventing the polymer from blocking the ethylene / circulating gas feeding pipes, and achieving the purpose of long-period operation of the production device.

[0082] The outer wall of the reaction kettle is provided with a jacket 120, cold or hot medium can be introduced into the jacket 120, so that the device can be heated when starting, and the purpose of removing heat during normal production can be achieved. The circulating gas discharged from the circulating gas outlet pipe 106 is condensed through the kettle outer heat exchanger, and then the gas phase is returned to the reaction kettle through the ethylene / circulating gas inlet pipe 101, and the liquid phase is returned to the reaction kettle through the condensate inlet pipe 103 or the ethylene / circulating gas inlet pipe 101. Through the jacket 120 and the outer circulating heat exchange of the gas phase, the stable control of the polymerization reaction temperature can be realized.

[0083] Example 1

[0084] Referring to Figure 1 The reaction kettle for synthesizing ultra-high molecular weight polyethylene provided by the utility model is used for ethylene polymerization to produce ultra-high molecular weight polyethylene. When the polymerization kettle is used for ethylene polymerization to produce ultra-high molecular weight polyethylene with a molecular weight of 700-800 million, 8 ethylene / circulating gas inlet pipes 101, wherein 6 pipes are used for ethylene and circulating gas in the gas phase, and 2 pipes are used for mother liquor and solvent, and the 2 inlet pipes for mother liquor and solvent are switched once every 6 hours, so that each inlet pipe is washed online for 6 hours every 24 hours. After such online washing, there is no blockage at the bottom of the inlet pipe, and the continuous long-period operation of the production device can be ensured.

[0085] Comparative Example 1

[0086] Referring to Figure 1 The reaction kettle for synthesizing ultra-high molecular weight polyethylene provided by the utility model is used for ethylene polymerization to produce ultra-high molecular weight polyethylene. When the polymerization kettle is used for ethylene polymerization to produce ultra-high molecular weight polyethylene with a molecular weight of 700-800 million, 8 ethylene / circulating gas inlet pipes 101, all of which are used for ethylene and circulating gas in the gas phase, after the production device is operated for 72 hours, blockage occurs at the bottom of the inlet pipe, and the blockage becomes more and more serious as the production continues. After the production device is operated for 200 hours, the circulating gas fan is over-pressured due to the blockage at the bottom of the inlet pipe, and the production device is forced to stop.

[0087] In summary, the utility model has the beneficial effects that: the reaction kettle adopts a combined stirring paddle, strengthens the radial circulation flow in the reaction kettle according to the reaction characteristics, and improves the mass transfer effect; the online switching and online washing of the ethylene / circulating gas injection pipe can solve the problem of polymer blockage at the bottom of the injection pipe.

[0088] The above is only a preferred embodiment of the present application, and is not intended to limit the present application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A reactor for the polymerization of ethylene to produce ultra-high molecular weight polyethylene, characterized in that, The kettle body (100) comprises a kettle body (100), The kettle body (100) is provided with a stirring shaft (200), the stirring shaft (200) penetrates the top of the kettle body (100) and is connected with a motor (300), a stirring paddle (210) is horizontally arranged on the stirring shaft (200), and the stirring paddle (210) is located at the middle and lower end of the stirring shaft (200); a liquid distribution net (220) is horizontally arranged on the upper portion of the stirring shaft (200), and the liquid distribution net (220) is located in the kettle body (100); The kettle body (100) is provided with eight ethylene / circulating gas feeding pipes (101), when continuously operating, five to seven ethylene / circulating gas feeding pipes (101) are used for feeding mixed gas of ethylene and circulating gas, and one to three ethylene / circulating gas feeding pipes (101) are used for feeding liquid, and switching is carried out; the inner wall of the kettle body (100) is provided with at least one support (102) for supporting the eight ethylene / circulating gas feeding pipes (101); The top of the kettle body (100) is provided with a condensate inlet pipe (103), an insertion type discharge pipe (104) with adjustable insertion depth; the bottom of the kettle body (100) is provided with a mother liquor inlet pipe (105); the kettle body (100) is further provided with a catalyst inlet pipe (107) and at least one circulating gas outlet pipe (106); the outer side of the kettle body (100) is provided with a jacket (120) for heating or cooling medium.

2. The reaction kettle according to claim 1, wherein, The stirring shaft (200) and the kettle body (100) are connected through a bearing; and the stirring shaft (200) is connected with the motor (300) through a shaft coupling. The stirring shaft (200) is uniformly provided with at least one layer of stirring paddles (210) from bottom to top.

3. The reaction kettle according to claim 2, wherein, The stirring shaft (200) is uniformly provided with three layers of stirring paddles (210) from bottom to top, which are respectively a first layer of stirring paddles, a second layer of stirring paddles and a third layer of stirring paddles.

4. The reaction kettle according to claim 3, wherein, Each layer of stirring paddles (210) comprises at least one radial flow stirring blade (211) and at least one axial flow stirring blade (212); the radial flow stirring blade (211) is fixedly connected with the stirring shaft (200); and the axial flow stirring blade (212) is fixedly arranged at the lower portion of the radial flow stirring blade (211).

5. The reaction kettle according to claim 1, wherein, The liquid distribution net (220) is formed by stacking multiple layers of screens; The liquid distribution net (220) is located above the stirring paddles (210), and the condensate inlet pipe (103) is located above the liquid distribution net (220).

6. The reaction kettle according to claim 1, wherein, The outlets of the eight ethylene / circulating gas feeding pipes (101) are located between the first layer of stirring paddles and the second layer of stirring paddles.

7. The reaction kettle according to claim 1, wherein, The number of supports for supporting the eight ethylene / circulating gas feeding pipes (101) is three.

8. The reaction kettle according to claim 7, wherein, The inner wall of the kettle body (100) is fixed from bottom to top with a layer of support for supporting 8 ethylene / cycle gas feed pipes (101), a second layer of support, and a third layer of support.

9. The reaction kettle of claim 7, wherein, The support (102) is a square with rounded corners structure.

10. The reaction kettle of claim 1, wherein, The jacket (120) is wrapped on the outside of the middle and lower kettle body (100). The jacket (120) is provided with a jacket water inlet (121) and a jacket water outlet (122), the jacket water inlet (121) is located at the bottom of the jacket (120), and the jacket water outlet (122) is located at the upper part of the jacket (120).

11. The reaction kettle of claim 1, wherein, The kettle body is provided with two cycle gas outlets (106) located at the top of the kettle body (100) and the lower part of the kettle body (100). The cycle gas outlet (106) has an expansion section at the outlet. The cycle gas outlet (106) has an online condensate flushing function, which is realized by controlling the on-off valve on the cycle gas outlet or its connected pipeline. The discharge pipe (104) has an online solvent flushing function, which is realized by controlling the on-off valve on the discharge pipe (104) or its connected pipeline.

12. The reaction kettle of claim 1, wherein, The kettle body (100) is provided with at least one remote thermometer (108); The top of the kettle body (100) is provided with a remote pressure gauge (109); The kettle body (100) is provided with at least one remote liquid level meter (110).

13. The reaction kettle of claim 1, wherein, The catalyst inlet pipe (107) is located at the lower part of the kettle body; The top of the kettle body (100) is also provided with an emergency discharge pipe (111) provided with a safety valve interface; the bottom of the kettle body (100) is provided with a kettle bottom discharge pipe (112); The outside of the kettle body (100) is provided with a manhole (113); the manhole (113) is located at the middle position of the kettle body (100).

Images