Ethylene polymerization continuous production device, production method and application

Abstract

The invention provides a continuous production device for ethylene polymerization, a production method and application, and particularly relates to a polymerization system process for generating a lubricant base oil product by catalytic polymerization in a solvent by taking ethylene as a raw material. Wherein a reactor continuous discharge control system, a reactor external circulation heat removal system, a polymerization product molecular weight control system and an emergency termination system in a reaction out-of-control state of the polymerization reactor are arranged, so that the product quality stability and the operation convenience are improved, and the method is suitable for large-scale industrial production.

Description

Technical Field

[0001] The present invention belongs to the technical field of ethylene polymerization, and particularly relates to a continuous production device, a production method and an application for ethylene polymerization. Background Art

[0002] Lubricating oil is an extremely important oil product in industry and is the fourth largest oil product after gasoline, diesel and kerosene. Base oil is an important component of lubricating oil, accounting for 70-95% of lubricating oil. Lubricating oil is mainly composed of base oil and various additives. Therefore, the properties of lubricating oil are mainly determined by its base oil. Currently, the commonly used base oils internationally include mineral oil (API-III) and synthetic oil (API IV-V). Among them, fully synthetic oil (API-IV, i.e., polyalphaolefin PAO) has characteristics such as a wide operating temperature range, good viscosity-temperature performance, high viscosity index, low pour point, small evaporation loss, good oxidation stability and environmental friendliness, and is a kind of high-quality lubricating oil base oil, which is applied to many high-end fields.

[0003] Chinese Patent CN209985405 U provides an integrated experimental system for measuring the scale-up effect of a stirred reactor. In the chemical process, mass, heat and momentum transfer occur. With the change of scale, the material of production equipment, the specifications of raw materials, the production process conditions, the production mode, the product yield, etc. will all change. Especially, the process conditions are quite different from the product yield and the laboratory results, which is attributed to the "scale-up effect". The outlet of the reactor needs special design, resulting in a high construction cost of the reactor.

[0004] Chinese Patent CN110918018A discloses a combined heat removal method for a stirred slurry polyethylene reactor. The heat removal of the reactor jacket is limited by the outer surface area of the reactor. The larger the reactor is, the smaller the proportion of heat removal is. Therefore, when the production scale of the stirred slurry polyethylene process device expands to a certain extent, the heat removal problem still becomes the bottleneck of the production device, thus restricting the further expansion of the scale of the polyethylene process production device.

[0005] Chinese Patent CN116143576A provides a heat removal process and a heat removal system for the reaction of selective polymerization of ethylene to produce α-olefins. The selective polymerization reaction of ethylene is a strongly exothermic reaction. The over-temperature reaction of the reactor will lead to a poor selectivity of the target product and even deactivation of the catalyst. At the same time, some solid polymers will be generated in this reaction. To prevent the entanglement and retention of solid polymers in the reactor, it is not suitable to set a conventional condensing coil for heat removal in the reactor, and it is very difficult to rely only on the jacket for heat removal, and it is difficult to ensure the effective removal of the reaction heat in the reactor. Summary of the Invention

[0006] To solve the above technical problems, the present invention provides a polymerization system process for catalytic polymerization of ethylene as a raw material in a solvent to produce a lubricating base oil product, in which a continuous discharge control system for the reactor, an external circulation heat removal system for the reactor, a molecular weight control system for the polymerization product, and an emergency termination system in the event of a reaction runaway in the polymerization reactor are provided.

[0007] One object of the present invention is to provide a continuous production device for ethylene polymerization, comprising: a reactor, a flash evaporator and a gas-liquid separator connected in sequence by pipelines, an external circulation heat removal system is provided outside the reactor, and at least one material mixer is provided inside the reactor.

[0008] According to the present invention, in the continuous production device for ethylene polymerization:

[0009] A raw material inlet is provided on the side line of the reactor. The position of the raw material inlet is not particularly limited and can be set according to actual operation. For example, the raw material inlet is set at 1 / 8 to 7 / 8 from the top down on the side line of the reactor;

[0010] A catalyst inlet is provided on the side line of the reactor. The position of the catalyst inlet is not particularly limited and can be set according to actual operation. For example, the catalyst inlet is set at 1 / 8 to 7 / 8 from the top down on the side line of the reactor;

[0011] The external circulation heat removal system is composed of components including a branch connected to an external circulation heat exchanger from the outlet pipeline at the bottom of the reactor to the top of the reactor; preferably,

[0012] The external circulation heat exchanger is a heat exchanger. More preferably, the heat exchanger is a vertical shell-and-tube heat exchanger, and baffles are provided along the periphery of the outermost heat exchange tubes at both ends inside the heat exchanger; the baffles are provided at both ends of the heat exchange tubes, and the shape of the provided baffles is not particularly limited and can be conical, arc-shaped, etc. Its function is to divert all the materials into the heat exchanger for heat exchange to avoid material accumulation at dead corners inside the heat exchanger;

[0013] A circulation pump is provided on the material outlet pipeline at the bottom of the reactor. The material pipeline at the outlet of the circulation pump includes two branches. One branch is connected to the material inlet of the heat exchanger, and the other branch is connected to the flash evaporator.

[0014] According to the present invention, in the continuous production device for ethylene polymerization:

[0015] A material inlet is provided on the side line of the flash evaporator, a reflux material inlet is provided on the upper side line, a liquid phase outlet is provided at the bottom, and a gas phase outlet is provided at the top; among them, the position of the material inlet is not particularly limited and can be set according to actual operation. For example, the material inlet is set at 1 / 10 to 9 / 10 from the top down on the side line of the flash evaporator;

[0016] The side line of the gas-liquid separator is provided with a material inlet, the bottom is provided with a liquid phase outlet, and the top is provided with a gas phase outlet; among them, the position of the material inlet is not particularly limited and can be set according to actual operation. For example, the material inlet is set at 1 / 10 to 9 / 10 from top to bottom of the side line of the gas-liquid separator;

[0017] The gas phase outlet at the top of the flash evaporator is connected to the material inlet on the side line of the gas-liquid separator by a pipeline. Preferably, a discharge pump is provided on the pipeline of the liquid phase outlet at the bottom of the flash evaporator and is connected to the product storage tank or the post-treatment process by a pipeline, and a cooler is provided on the connecting pipeline between the gas phase outlet at the top of the flash evaporator and the material inlet on the side line of the gas-liquid separator;

[0018] The liquid phase outlet at the bottom of the gas-liquid separator is connected to the reflux material inlet on the upper side line of the flash evaporator by a pipeline. The position of the reflux material inlet on the side line can be set according to actual operation. For example, the reflux material inlet on the upper side line of the flash evaporator is set at 1 / 10 to 9 / 10 from top to bottom of the side line of the flash evaporator;

[0019] A compressor is provided on the pipeline of the gas phase outlet at the top of the gas-liquid separator and is connected to the solvent recovery tank by a pipeline.

[0020] According to the present invention, in the continuous production device for ethylene polymerization, a control valve V-01 is provided on the pipeline of the reactor raw material inlet, and a reaction emergency termination system is provided at the top of the reactor. The reaction emergency termination system is electrically connected to the control valve V-01; when the reaction gets out of control due to excessive catalyst addition, failure to strictly control the material ratio, operation errors, cooling failure, etc., or when the reactor temperature is abnormal or the pressure rises above the set value, the termination program of the reaction emergency termination system is immediately started, and the raw material feed valve is interlocked and closed to stop the raw material feed of the reaction kettle.

[0021] According to the present invention, in the continuous production device for ethylene polymerization, a control valve V-02 is provided on the pipeline of the reactor catalyst inlet, and a molecular weight control system is provided on the pipeline of the reactor material outlet. The molecular weight control system is electrically connected to the control valve V-02. The smaller the molecular weight distribution range of the vinyl lubricating oil base oil, the better its product performance. A polymer molecular weight detection device is provided at the reactor outlet. The molecular weight control system controls the catalyst feed amount of the reactor according to the detection result. Specifically, when the molecular weight of the polymerization product is greater than the set range, the catalyst feed amount of the reactor is controlled to decrease, and when the molecular weight of the polymerization product is less than the set range, the catalyst feed amount of the reactor is controlled to increase; and accordingly, the molecular weight distribution range of the polymerization product is controlled according to production needs.

[0022] According to the present invention, in the continuous production device for ethylene polymerization, a control valve V-03 is provided on the pipeline at the flash tank material inlet, and a liquid level controller is provided on the side line of the reactor. The liquid level controller is electrically connected to the control valve V-03 to ensure the stability of the liquid level in the reactor and prevent the medium from overflowing due to overpressure when the liquid level in the reactor is too high or a large amount of ethylene from entering the subsequent system when the liquid level is too low. Specifically, when the liquid level in the reactor is higher than the set range, the control is to increase the amount of flash tank material entering; when the liquid level in the reactor is lower than the set range, the control is to reduce the amount of flash tank material entering.

[0023] According to the present invention, in the continuous production device for ethylene polymerization, a control valve V-04 is provided on the pipeline at the gas-phase outlet at the top of the gas-liquid separator, and a pressure controller is provided on the top of the flash tank. The pressure controller is electrically connected to the control valve V-04 to control the pressure in the flash tank at 0 - 2.0 MPaG. Specifically, when the pressure in the flash tank is higher than the set range, the control is to increase the gas-phase discharge amount of the gas-liquid separator; when the pressure in the flash tank is lower than the set range, the control is to reduce the gas-phase discharge amount of the gas-liquid separator.

[0024] According to the present invention, in the continuous production device for ethylene polymerization, a control valve V-05 is provided on the pipeline at the product storage tank inlet, and a liquid level controller is provided on the side line of the flash tank. The liquid level controller is electrically connected to the control valve V-05 to control the discharge of the polyethylene product after flashing by observing the liquid level in the flash tank. Specifically, when the liquid level in the flash tank is higher than the set range, the control is to increase the discharge amount of the polyethylene product; when the liquid level in the flash tank is lower than the set range, the control is to reduce the discharge amount of the polyethylene product.

[0025] According to the present invention, in the continuous production device for ethylene polymerization:

[0026] The mixer is columnar with an axially reduced diameter in the middle; preferably, the side wall shape of the longitudinal section of the center line of the mixer is an arc, and the arc bends towards the inner side of the mixer; preferably, the arc is a circular arc and is symmetric up and down with the center horizontal ring line of the mixer as the axis; more preferably, the radius of the circular arc is 1 - 8 times, preferably 2 - 5 times, the diameter of the mixer inlet pipeline.

[0027] The mixer is vertically fixed at the center line position of the reactor;

[0028] A circulating material inlet is provided at the top of the mixer and is connected to the circulating material inlet at the top of the reactor by a pipeline;

[0029] At least 2 openings are evenly distributed on the center horizontal ring line of the side wall of the mixer. Preferably, 2 - 20 openings are evenly distributed, and the diameter of the opening is preferably 1 / 10 - 2 / 3 of the diameter of the mixer material inlet pipeline.

[0030] According to the present invention, in the continuous production device for ethylene polymerization:

[0031] When the recycled material is a gas-phase component, a mixer is provided in the reactor, and the mixer is provided above the liquid level of the reactor; or,

[0032] When the recycled material is a liquid-phase component, a mixer is provided in the reactor, and the mixer is provided below the liquid level of the reactor; or,

[0033] When the recycled material is a gas-liquid mixture, two mixers are vertically provided in the reactor, and the two mixers are fixedly connected along the axial direction. One mixer is provided above the liquid level of the reactor, and a material outlet is provided at its bottom and is connected to the recycled material inlet pipeline at the top of the other mixer; the other mixer is provided below the liquid level of the reactor.

[0034] The second object of the present invention is to provide a continuous production method for ethylene polymerization, and polyethylene is continuously and massively produced by adopting the above device.

[0035] According to the present invention, the continuous production method for ethylene polymerization includes the following steps:

[0036] (1) Feed ethylene, solvent and catalyst into the reactor, and heat for polymerization reaction;

[0037] (2) The product after the polymerization reaction is divided into two parts. One part of the product is cooled by a heat exchanger and then enters the mixer in the reactor, and continues the polymerization reaction after mixing with the raw materials entering the reactor; the other part of the product enters a flash evaporator for flash evaporation treatment to obtain a gas-phase component G1 and a liquid-phase component L1;

[0038] (3) The gas-phase component G1 obtained by the flash evaporation treatment is cooled and then enters a gas-liquid separator for separation to obtain a gas-phase component G2 and a liquid-phase component L2. The liquid-phase component L2 is returned to the flash evaporator, and the gas-phase component G2 is transported to a solvent recovery tank by a compressor;

[0039] (4) The liquid-phase component L1 obtained by the flash evaporation treatment is transported to a product storage tank by a discharge pump.

[0040] According to the present invention, in the continuous production method for ethylene polymerization:

[0041] The operating conditions of the reactor are as follows: the reaction is carried out in a protective gas atmosphere, the operating temperature is 10-60°C; the operating pressure is 0.1-2.0 MPaG; the protective gas can be selected from common nitrogen;

[0042] The operating conditions of the heat exchanger are as follows: the material outlet temperature is -20 to 60 °C, and the material inlet temperature is 1 to 20 °C higher than the outlet temperature; the material outlet operating pressure is 0.1 to 2.0 MPaG, and the material inlet operating pressure is 0 to 2.0 MPaG higher than the outlet pressure; the refrigerant inlet temperature is 0 to 100 °C lower than the material outlet temperature, and the refrigerant inlet pressure is 0.01 to 0.5 MPaG; the refrigerant of the heat exchanger can be water or an ethylene glycol aqueous solution;

[0043] The operating conditions of the flash evaporator are as follows: the temperature is 10 to 200 °C, and the pressure is 0 to 2.0 MPaG;

[0044] The operating conditions of the gas-liquid separator are as follows: the temperature is 10 to 200 °C, and the pressure is 0 to 2.0 MPaG.

[0045] According to the present invention, in the continuous production method of ethylene polymerization:

[0046] The solvent is selected from at least one of alkanes having 6 to 12 carbon atoms, white oil, toluene, xylene, and halogenated alkanes having 1 to 12 carbon atoms;

[0047] The catalyst is selected from at least one of triethylaluminum, trimethylaluminum, diethylaluminum chloride, ethylaluminum dichloride, triethylaluminum chloride, ethyl sesquialuminum chloride, and triisobutylaluminum;

[0048] The mass ratio of ethylene to the solvent is 1:(0.5 to 10);

[0049] The dosage of the catalyst is 0.001 to 0.1 wt% of ethylene;

[0050] The product entering the flash evaporator in step (2) is 80 to 95% of the total amount of the post-polymerization reaction product.

[0051] According to the present invention, in the continuous production method of ethylene polymerization, the conversion rate of ethylene in the polymerization reaction is 95 to 97%, and the product yield is 92 to 94%.

[0052] The third object of the present invention is to provide an application of the above-mentioned continuous production device for ethylene polymerization or the above-mentioned continuous production method for ethylene polymerization in the production of vinyl lubricant base oil.

[0053] The present invention provides a polymerization system process and method for catalytically polymerizing ethylene as a raw material in a solvent to produce a lubricating base oil product. The polymerization system includes a polymerization reactor, an emergency termination system, a continuous discharge control system, and a polymerization product molecular weight control system, and can achieve commercial continuous production of LPE products on an industrial scale with a nominal scale of 200 tons / year to 50,000 tons / year. The polymerization reactor uses external circulation to remove heat. In the polymerization reaction, the conversion rate of the ethylene raw material is 95-97%, and the yield of the primary product is 92-94%. The termination system is simple and reliable, achieving good technical effects.

[0054] Compared with the prior art, the advantages of the present invention are as follows:

[0055] (1) The present invention provides a continuous production process for catalytically polymerizing ethylene as a raw material in a solvent. Compared with batch reactions, the product quality stability and operation convenience are improved;

[0056] (2) The present invention uses external circulation to remove heat, which is beneficial to a stable polymerization reaction process in large-scale production;

[0057] (3) A mixer is installed inside the reactor to ensure uniform mixing of the freshly added supplementary materials and the original materials in the reaction kettle. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 It is a schematic diagram of a continuous production device for ethylene polymerization. Figure 1 In it, A - Mixer A; B - Mixer B; R-01 - Reactor; D-01 - Flash evaporator; D-02 - Gas-liquid separator; C-01 - Compressor; E-01 - External circulation heat removal device; E-02 - Cooler; P-01 - Circulation pump; P-02 - Discharge pump.

[0059] Figure 2 It is a schematic diagram of the external circulation heat removal system of the reactor. Figure 2 In it, 1-1 - Raw material logistics, 1-2 - Catalyst logistics, 2 - Reactor, 3 - Outlet logistics of the reaction kettle, 4 - Circulation pump, 5 - Outlet logistics of the circulation pump, 6 - Heat exchanger, 7 - Outlet logistics of the heat exchanger, 8 - Baffle of the heat exchanger, 9 - Inlet of the circulating material of Mixer A, 10 - Opening of Mixer A, 11 - Inlet of the circulating material of Mixer B, 12 - Opening of Mixer B.

[0060] Figure 3 It is a schematic diagram of the emergency killing system of the reactor. Figure 3 In it, 1 - Raw material logistics, 2 - Reactor, 3 - Outlet logistics of the reaction kettle.

[0061] Figure 4 It is a schematic diagram of the polymerization product molecular weight control system. Figure 4 In it, 1 - Catalyst logistics, 2 - Reactor, 3 - Outlet logistics of the reaction kettle. Detailed implementation manners

[0062] The present invention will be specifically described below in conjunction with specific embodiments. It is necessary to point out here that the following embodiments are only used for further illustration of the present invention and cannot be construed as limiting the protection scope of the present invention. Some non-essential improvements and adjustments made by those skilled in the art to the present invention based on the content of the present invention still fall within the protection scope of the present invention.

[0063] For the raw materials used in the examples and comparative examples, if not specifically limited, they are all disclosed in the prior art. For example, they can be directly purchased or prepared according to the preparation methods disclosed in the prior art.

[0064] Example 1

[0065] The following will be combined with Figures 1 to 4 to illustrate the continuous production device for ethylene polymerization provided in Example 1.

[0066] As Figure 1 shown, the continuous production device for ethylene polymerization includes a reactor R-01, a flash separator D-01, and a gas-liquid separator D-02 connected in sequence by pipelines. A pipeline branch is provided at the bottom of the reactor R-01 to connect the external circulation heat exchanger E-01 to the top of the reactor R-01 to form an external circulation heat removal reaction system. The external circulation heat exchanger E-01 is a vertical shell-and-tube heat exchanger. A circulation pump P-01 is provided on the pipeline of the material outlet at the bottom of the reactor R-01. The pipeline of the material outlet of the circulation pump includes two branches. One branch is connected to the material inlet of the heat exchanger E-01, and the other branch is connected to the material inlet of the flash separator D-01. The gas-phase outlet at the top of the flash separator D-01 is connected by a pipeline to the side-line material inlet of the gas-liquid separator D-02. A discharge pump P-02 is provided on the pipeline of the liquid-phase outlet at the bottom of the flash separator D-01 and is connected by a pipeline to the product storage tank or the post-treatment process; a cooler E-02 is provided on the connecting pipeline between the gas-phase outlet at the top of the flash separator D-01 and the side-line material inlet of the gas-liquid separator D-02. The liquid-phase outlet at the bottom of the gas-liquid separator D-02 is connected by a pipeline to the upper side-line inlet of the flash separator D-01. A compressor C-01 is provided on the pipeline of the gas-phase outlet at the top of the gas-liquid separator D-02 and is connected by a pipeline to the solvent recovery tank.

[0067] A control valve V-03 is provided on the pipeline of the material inlet of the flash separator D-01. A liquid level controller is provided on the side line of the reactor. The liquid level controller is electrically connected to the control valve V-03. A control valve V-04 is provided on the pipeline of the gas-phase outlet at the top of the gas-liquid separator D-02. A pressure controller is provided on the top of the flash separator. The pressure controller is electrically connected to the control valve V-04. A control valve V-05 is provided on the pipeline of the product storage tank inlet. A liquid level controller is provided on the side line of the flash separator. The liquid level controller is electrically connected to the control valve V-05.

[0068] In the above device, the radius of the arc-shaped structure on the side walls of mixers A and B is 5 times the diameter of the inlet pipeline of the mixer, and 20 openings are evenly distributed at the positions of the central circular lines 10 and 12 on the side walls of mixers A and B. The diameter of the openings is 1 / 10 of the pipeline diameter at the material inlets 9 or 11 of the mixer.

[0069] In the above device, the side-line raw material inlet of reactor R-01 is set at the 3 / 5 position from top to bottom of the reactor side line; the side-line catalyst inlet of reactor R-01 is set at the 1 / 5 position from top to bottom of the reactor side line; the material inlet of the polymer product in flash separator D-01 is set at the 3 / 5 position from top to bottom of the flash separator side line; the side-line material inlet of gas-liquid separator D-02 is set at the 3 / 5 position from top to bottom of the gas-liquid separator side line; the upper side-line inlet of the flash separator is set at the 1 / 5 position from top to bottom of the flash separator side line.

[0070] As Figure 2 shown, reactor 2 is internally provided with mixer A and mixer B, and mixers A and B are columnar structures with a reduced diameter in the axial middle. The side walls of mixers A and B are arc-shaped structures, and the arc-shaped structures bend towards the inner side of the mixer; mixers A and B are vertically fixed on the reactor center line; a circulating material inlet is provided at the top of mixer A, and is connected to the top circulating material inlet of reactor 2 by a pipeline. Mixer A is arranged above the liquid level of reactor 2, and mixer B is arranged below the liquid level of reactor 2. Baffles 8 are arranged along the periphery of the outermost heat exchange tubes at both ends inside heat exchanger 6.

[0071] As Figure 3 shown, a control valve V-01 is arranged on the pipeline of the raw material inlet of reactor R-01, and a reaction emergency termination system is arranged at the top of the reactor. The reaction emergency termination system is electrically connected to control valve V-01.

[0072] As Figure 4 shown, a control valve V-02 is arranged on the pipeline of the catalyst inlet of reactor R-01, and a molecular weight control system is arranged on the pipeline of the reactor material outlet. The molecular weight control system is electrically connected to control valve V-02.

[0073] Using Figures 1 to 4 the device, a continuous production method for ethylene polymerization is specifically described, including:

[0074] (1) Feed ethylene (1373 kg / h), solvent dichloromethane (5000 kg / h), and catalyst triethylaluminum chloride (0.5 kg / h) into the reactor through the reactor raw material inlet, and heat for polymerization reaction; the operating conditions of the reactor are: the reaction is carried out in a nitrogen atmosphere, the operating temperature: 40 °C; the operating pressure: 1.0 - 1.2 MPaG.

[0075] (2) The product after the polymerization reaction is divided into two parts. One part of the product enters the mixer in the reactor after being cooled by the heat exchanger, and then continues the polymerization reaction after being mixed with the raw materials entering the reactor; the other part of the product enters the flash evaporator for flash evaporation treatment to obtain a gas-phase component and a liquid-phase component. Among them, the product entering the flash evaporator is 82-83% of the total amount of the product after the polymerization reaction; the operating conditions of the heat exchanger are: the outlet temperature of the material is 35°C, and the inlet temperature of the material is 40°C; the operating pressure at the outlet of the material is 1.2 MPaG, and the operating pressure at the inlet of the material is 1.2 MPaG; the refrigerant is 20 wt% ethanol aqueous solution, the inlet temperature is -10°C, and the refrigerant inlet pressure is 0.5 MPaG; the operating conditions of the flash evaporator are: the temperature is 40°C, and the pressure is 0.8 MPaG.

[0076] (3) The gas-phase component obtained by the flash evaporation treatment is cooled and then enters the gas-liquid separator for separation. The separated liquid phase returns to the flash evaporator, and the separated gas phase is transported to the solvent recovery tank by a compressor; the operating conditions of the gas-liquid separator are: the temperature is 40°C, and the pressure is 0.8 MPaG.

[0077] (4) The liquid-phase component obtained by the flash evaporation treatment is transported to the product storage tank by a discharge pump.

[0078] Using the production method of Example 1, the flow rate of the product polyethylene is 1250 kg / h, the yield is 91%, and the ethylene conversion rate is 98.5%. The molecular weight of the product is measured by GPC to be 980 g / mol, and the molecular weight distribution is 1.3.

[0079] Example 2

[0080] Using Figures 1 to 4 the device, the continuous production method of ethylene polymerization is specifically described, including:

[0081] (1) Ethylene (1413 kg / h), solvent dichloromethane (5000 kg / h), and catalyst triethylaluminum chloride (0.08 kg / h) are fed into the reactor through the reactor raw material inlet, and heated for polymerization reaction; the operating conditions of the reactor are: the reaction is carried out under a nitrogen atmosphere, the operating temperature: 60°C; the operating pressure: 1.5 MPaG;

[0082] (2) The product after the polymerization reaction is divided into two parts. One part of the product enters the mixer in the reactor after being cooled by the heat exchanger, and then is mixed with the raw materials entering the reactor and continues the polymerization reaction; the other part of the product enters the flash evaporator for flash treatment to obtain a gas-phase component and a liquid-phase component. Among them, the product entering the flash evaporator is 86-87% of the total amount of the product after the polymerization reaction; the operating conditions of the heat exchanger are: the outlet temperature of the material is 55 °C, and the inlet temperature of the material is 60 °C; the operating pressure at the outlet of the material is 1.5 MPaG, and the operating pressure at the inlet of the material is 1.8 MPaG; the refrigerant is 20 wt% ethanol aqueous solution, the inlet temperature is -20 °C, and the refrigerant inlet pressure is 0.5 MPaG; the operating conditions of the flash evaporator are: the temperature is 60 °C, and the pressure is 1.1 MPaG.

[0083] (3) Emergency shutdown system: When the reactor pressure rises to 1.8 MPaG, the raw material feed valve controlled by the top pressure of the reactor is closed, there is no raw material feed in the reactor, the reaction stops, and the pressure gradually decreases.

[0084] Molecular weight control system: A product molecular weight detection instrument is set at the reactor outlet, and the catalyst feed rate of the reactor is dynamically adjusted according to the detection results. In this example, the molecular weight of the product is controlled to be 1250 g / mol, the molecular weight distribution is 1.6, and the corresponding feed rate of the catalyst triethylaluminum chloride is controlled to be 50 kg / h.

[0085] (4) The gas-phase component obtained by the flash treatment is cooled and then enters the gas-liquid separator for separation. The separated liquid phase returns to the flash evaporator, and the separated gas phase is transported to the solvent recovery tank by a compressor; the operating conditions of the gas-liquid separator are: the temperature is 60 °C, and the pressure is 1.1 MPaG.

[0086] (5) The liquid-phase component obtained by the flash treatment is transported to the product storage tank by a discharge pump.

[0087] Using the production method of Example 2, the flow rate of the product polyethylene is 1300 kg / h, the yield is 92%, and the ethylene conversion rate is 99%. The molecular weight of the product measured by GPC is 1250 g / mol, and the molecular weight distribution is 1.6.

[0088] Example 3

[0089] Using Figures 1 to 4 the device, a continuous production method for ethylene polymerization is specifically described, including:

[0090] (1) Ethylene (1254 kg / h), solvent 1,1,2,2-tetrachloroethane (5000 kg / h), and catalyst diethylaluminum chloride (0.02 kg / h) are fed into the reactor through the reactor raw material inlet and heated for polymerization reaction; the operating conditions of the reactor are: the reaction is carried out in a nitrogen atmosphere, the operating temperature: 20 °C; the operating pressure: 0.5 MPaG.

[0091] (2) The product after the polymerization reaction is divided into two parts. One part of the product enters the mixer in the reactor after being cooled by the heat exchanger, and then continues the polymerization reaction after being mixed with the raw materials entering the reactor. The other part of the product enters the flash evaporator for flash evaporation treatment to obtain a gas-phase component and a liquid-phase component. Among them, the product entering the flash evaporator is 91-92% of the total amount of the product after the polymerization reaction. The operating conditions of the heat exchanger are: the outlet temperature of the material is 10°C, and the inlet temperature of the material is 20°C; the outlet operating pressure of the material is 0.5 MPaG, and the inlet operating pressure of the material is 0.8 MPaG; the refrigerant is 20 wt% ethanol aqueous solution, the inlet temperature is 0°C, and the refrigerant inlet pressure is 0.5 MPaG; the operating conditions of the flash evaporator are: the temperature is 20°C, and the pressure is 0.2 MPaG.

[0092] (3) The gas-phase component obtained by the flash evaporation treatment enters the gas-liquid separator for separation after being cooled. The separated liquid phase returns to the flash evaporator, and the separated gas phase is transported to the solvent recovery tank by a compressor. The operating conditions of the gas-liquid separator are: the temperature is 20°C, and the pressure is 0.2 MPaG.

[0093] (4) The liquid-phase component obtained by the flash evaporation treatment is transported to the product storage tank by a discharge pump.

[0094] Using the production method of Example 3, the flow rate of the product polyethylene is 1150 kg / h, the yield is 91.4%, and the ethylene conversion rate is 98%. The molecular weight of the product is measured to be 2000 g / mol by GPC, and the molecular weight distribution is 1.8.

Claims

1. A continuous production device for ethylene polymerization, comprising: A reactor, a flash evaporator and a gas-liquid separator connected in sequence by pipelines. An external circulation heat removal system is provided outside the reactor, and at least one material mixer is provided inside the reactor.

2. The device according to claim 1, wherein a raw material inlet is provided on the side line of the reactor; and / or, a catalyst inlet is provided on the side line of the reactor; and / or, the external circulation heat removal system is composed of components including a branch pipeline connected to an external circulation heat exchanger from the outlet pipeline at the bottom of the reactor to the top of the reactor; preferably, the external circulation heat exchanger is a heat exchanger, and more preferably, the heat exchanger is a vertical shell-and-tube heat exchanger, and baffles are provided along the periphery of the outermost heat exchange tubes at both ends inside the heat exchanger; and / or, a circulation pump is provided on the material outlet pipeline at the bottom of the reactor, and the material pipeline at the outlet of the circulation pump includes two branch pipelines, one of which is connected to the material inlet of the heat exchanger, and the other is connected to the flash evaporator.

3. The device according to claim 1, wherein a material inlet is provided on the side line of the flash evaporator, a reflux material inlet is provided on the upper side line, a liquid phase outlet is provided at the bottom, and a gas phase outlet is provided at the top; and / or, a material inlet is provided on the side line of the gas-liquid separator, a liquid phase outlet is provided at the bottom, and a gas phase outlet is provided at the top; preferably, the gas phase outlet at the top of the flash evaporator is connected to the material inlet on the side line of the gas-liquid separator by a pipeline, and more preferably, a cooler is provided on the connecting pipeline between the gas phase outlet at the top of the flash evaporator and the material inlet on the side line of the gas-liquid separator; and / or, a discharge pump is provided on the liquid phase outlet pipeline at the bottom of the flash evaporator and is connected to a product storage tank or a post-treatment process by a pipeline; and / or, the liquid phase outlet at the bottom of the gas-liquid separator is connected to the reflux material inlet on the upper side line of the flash evaporator by a pipeline; and / or, a compressor is provided on the gas phase outlet pipeline at the top of the gas-liquid separator and is connected to a solvent recovery tank by a pipeline.

4. The device according to claim 2 or 3, wherein a control valve V-01 is provided on the pipeline of the raw material inlet of the reactor, and a reaction emergency termination system is provided at the top of the reactor, and the reaction emergency termination system is electrically connected to the control valve V-01; and / or, a control valve V-02 is provided on the pipeline of the catalyst inlet of the reactor, and a molecular weight control system is provided on the material outlet pipeline of the reactor, and the molecular weight control system is electrically connected to the control valve V-02; and / or, a control valve V-03 is provided on the pipeline of the material inlet of the flash evaporator, and a liquid level controller is provided on the side line of the reactor, and the liquid level controller is electrically connected to the control valve V-03; and / or, a control valve V-04 is provided on the pipeline of the gas phase outlet at the top of the gas-liquid separator, and a pressure controller is provided at the top of the flash evaporator, and the pressure controller is electrically connected to the control valve V-04; and / or, a control valve V-05 is provided on the pipeline of the inlet of the product storage tank, and a liquid level controller is provided on the side line of the flash evaporator, and the liquid level controller is electrically connected to the control valve V-05.

5. The device according to claim 1, wherein The mixer is columnar with a reduced diameter in the axial middle; preferably, the side wall shape of the longitudinal section of the center line of the mixer is an arc, and the arc bends towards the inner side of the mixer; preferably, the arc is a circular arc and is vertically symmetric about the horizontal circular line at the center of the mixer; more preferably, the radius of the circular arc is 1 to 8 times, preferably 2 to 5 times, the diameter of the inlet pipeline of the mixer; and / or, The mixer is vertically fixed at the center line position of the reactor; and / or, A circulating material inlet is arranged at the top of the mixer and is connected to the circulating material inlet at the top of the reactor by a pipeline; and / or, At least 2 openings are evenly distributed on the horizontal circular line at the center of the side wall of the mixer. Preferably, 2 to 20 openings are evenly distributed, and / or, the diameter of the opening is 1 / 10 to 2 / 3 of the diameter of the material inlet pipeline of the mixer.

6. The device according to claim 5, wherein, When the circulating material is a gas component, one mixer is arranged in the reactor, and the mixer is arranged above the liquid level of the reactor; or, When the circulating material is a liquid component, one mixer is arranged in the reactor, and the mixer is arranged below the liquid level of the reactor; or, When the circulating material is a gas-liquid mixture, two mixers are vertically arranged in the reactor. The two mixers are fixedly connected along the axis. One mixer is arranged above the liquid level of the reactor, and a material outlet is arranged at its bottom and is connected to the circulating material inlet pipeline at the top of the other mixer; the other mixer is arranged below the liquid level of the reactor.

7. A continuous production method for ethylene polymerization, which is used for continuous large-scale production of polyethylene by adopting the device according to any one of claims 1 to 6.

8. The production method according to claim 7, characterized in that, It includes the following steps: (1) Feed ethylene, solvent and catalyst into the reactor and heat for polymerization reaction; (2) The product after the polymerization reaction is divided into two parts. One part of the product is cooled by a heat exchanger and then enters the mixer in the reactor, and after mixing with the raw materials entering the reactor, continues the polymerization reaction; the other part of the product enters a flash evaporator for flash evaporation treatment to obtain a gas component G1 and a liquid component L1; (3) The gas component G1 obtained by the flash evaporation treatment is cooled and then enters a gas-liquid separator for separation to obtain a gas component G2 and a liquid component L2. The liquid component L2 returns to the flash evaporator, and the gas component G2 is transported to a solvent recovery tank by a compressor; (4) The liquid component L1 obtained by the flash evaporation treatment is transported to a product storage tank by a discharge pump.

9. The production method according to claim 8, wherein, The operating conditions of the reactor are: the reaction is carried out in an inert gas atmosphere, temperature: 10 to 60 °C; Pressure: 0.1 to 2.0 MPaG; and / or, The operating conditions of the heat exchanger are: the outlet temperature of the material is -20 to 60 °C, and the inlet temperature of the material is 1 to 20 °C higher than the outlet temperature; the outlet operating pressure of the material is 0.1 to 2.0 MPaG, and the inlet operating pressure of the material is 0 to 2.0 MPaG higher than the outlet; the inlet temperature of the refrigerant is 0 to 100 °C lower than the outlet temperature of the material, and the inlet pressure of the refrigerant is 0.01 to 0.5 MPaG; and / or, The operating conditions of the flash evaporator are: temperature is 10 to 200 °C, pressure is 0 to 2.0 MPaG; and / or, The operating conditions of the gas-liquid separator are as follows: the temperature is 10 to 200 °C, and the pressure is 0 to 2.0 MPaG.

10. The production method according to claim 8, wherein the solvent is selected from at least one of alkanes having 6 to 12 carbon atoms, white oil, toluene, xylene, and halogenated alkanes having 1 to 12 carbon atoms; and / or the catalyst is selected from at least one of triethylaluminum, trimethylaluminum, diethylaluminum chloride, ethylaluminum dichloride, triethylaluminum chloride, ethyl sesquialuminum chloride, and triisobutylaluminum; and / or the mass ratio of ethylene to the solvent is 1:(0.5 to 10); and / or the dosage of the catalyst is 0.001 to 0.1 wt% of ethylene; and / or the product entering the flash evaporator in step (2) is 80 to 95% of the total amount of the post-polymerization product.

11. The production method according to any one of claims 7 to 10, characterized in that, The conversion rate of ethylene in the polymerization reaction is 95 to 97%, and the product yield is 92 to 94%.

12. Use of a continuous production device for ethylene polymerization according to any one of claims 1 to 6 or a continuous production method for ethylene polymerization according to any one of claims 7 to 11 in the production of vinyl lubricant base oil.

Images