An evaluation method for an ethylene and alpha-olefin copolymerization evaluation device

Abstract

This invention discloses an evaluation method for an ethylene-α-olefin copolymerization evaluation test apparatus. The method includes the following steps: mixing ethylene and α-olefins in an olefin mixing and gas distribution device to obtain a mixed gas; adding a dispersant, catalyst, and molecular weight regulator to a polymerization reactor; conveying the mixed gas to a stirring paddle, and discharging the mixed gas from at least one gas outlet on the stirring paddle, thus initiating the polymerization reaction; controlling the reaction temperature and pressure within the polymerization reactor, and stopping the addition of mixed gas after the set reaction time has been reached; cooling the polymerization reactor using a temperature control unit, venting the gas from the polymerization reactor, adding nitrogen for purging, and discharging the reaction products. This invention's evaluation method for the ethylene-α-olefin copolymerization evaluation test apparatus increases the contact amount between ethylene and α-olefins and the catalyst. Using this method to evaluate ethylene polymerization can accurately assess catalyst activity.

Description

Technical Field

[0001] This invention relates to an evaluation method for an ethylene-α-olefin copolymerization evaluation device, and particularly to an ethylene-α-olefin copolymerization evaluation test device and a method for evaluating polyethylene catalysts using the device. It belongs to the field of chemical synthesis resin catalysts and new product technologies, specifically polyethylene catalysts, processes, and new product technologies. Background Technology

[0002] Currently, slurry polymerization, with its lower reaction pressure, easier-to-control operating conditions, and better product performance, is an important HDPE production technology in my country. In 2020, China's polyethylene market demand reached 38 million tons, domestic production capacity reached 23 million tons / year, and imports reached 18 million tons, with high-end products mainly relying on imports. With the rapid growth in demand for high-quality polyethylene products, competition in the polyethylene market is becoming increasingly fierce, and the specialization and high-end development of catalysts have become a trend. Slurry polymerization, with its lower reaction pressure, easier-to-control operating conditions, and better product performance, is one of the important HDPE production technologies in my country. Currently, the domestic slurry process HDPE production capacity is 7.5 million tons / year, requiring 300 tons / year of catalyst. Olefin polymerization involves the polymerization reaction of olefin monomers on solid catalyst particles. The resulting polymer replicates the particle morphology of the catalyst; except for varying degrees of particle size enlargement, its particle shape, particle size distribution, and bulk density are all directly related to the catalyst particle morphology.

[0003] Chinese patent CN201420680172.3 discloses a reaction vessel with a gas stirring mechanism. The technical description includes a reaction vessel body and a motor. The reaction vessel body is equipped with a stirring shaft, a gas chamber, and an exhaust valve. The exhaust valve is located below the gas chamber, and the gas chamber is equipped with an inlet valve. The upper end of the stirring shaft passes through the gas chamber and is connected to the motor. The stirring shaft has a hollow structure and is equipped with multiple inlet pipes, all located inside the gas chamber. The hollow part of the stirring shaft communicates with the gas chamber through the multiple inlet pipes. The lower end of the stirring shaft is equipped with a stirring tube with closed ends, and the stirring tube is equipped with multiple jet nozzles. The hollow part of the stirring shaft communicates with the multiple jet nozzles through the stirring tube. This utility model relates to a reactor with a gas stirring mechanism, which combines gas stirring with mechanical stirring, greatly improving stirring efficiency and allowing the reaction liquid to be mixed more thoroughly, thus significantly improving production reaction efficiency. This utility model relates to the field of chemical equipment technology, and in particular to a reactor with a gas stirring mechanism. However, it does not specify the application of such a reactor in the field of slurry ethylene polymerization evaluation tests, especially how to control the stability of reaction pressure and reaction temperature.

[0004] Chinese patent CN201921680358.8 discloses an olefin polymerization evaluation device. The technical description includes: It can precisely control the reaction temperature and avoid temperature runaway. The device includes a reactor, a heating jacket surrounding the reactor body, a circular lid on top of the reactor body, and the reactor body and lid are tightly fastened together by two semi-sealing jackets. A stirring motor is installed on the lid and connected to a stirring paddle inside the reactor. It also includes a pressure gauge; a thermocouple; a circulating condensate pipeline; three feed inlets; a vacuum pipeline and a vent. A stirring device and a thermocouple are connected to a digital display. The three feed inlets are a catalyst feed inlet, a raw material feed inlet, and a catalyst promoter feed inlet, each connected to a corresponding storage tank. The catalyst feed inlet... A metering valve is installed at the inlet, and a nitrogen pipeline is connected to the top of the raw material storage tank and the catalyst storage tank. A one-way valve is installed on the nitrogen pipeline. A condenser coil is attached to the stirring paddle inside the reactor, and a discharge port is located at the bottom of the reactor. The raw material inlet of this device is designed on the reactor lid. When evaluating ethylene polymerization under slurry process, ethylene monomer is added at the top of the polymerization reactor, and ethylene gas dissolves into the dispersant under certain temperature and pressure conditions. The polymerization process of this evaluation test is different from that of the slurry process industrial production device. In the slurry process industrial production device, ethylene is added from the bottom of the reactor during the polymerization reaction. Therefore, the existing slurry process ethylene polymerization evaluation test device is not accurate in evaluating the activity of the catalyst.

[0005] Fu Wenwen et al., in "Laboratory Evaluation Method for Activity of Slurry-Method Ethylene Polymerization Catalysts" ([J]. Industrial Catalysis, 2020, 28(5): 65-68.), established an activity evaluation device for slurry-method ethylene polymerization catalysts to provide customers with readily available ethylene catalyst activity evaluation data for product sales and after-sales service. Orthogonal experiments were used to determine the experimental parameters suitable for this laboratory device. This evaluation method can be used as a routine quality control inspection method for catalyst production and provide technical data support for downstream users. When evaluating the ethylene polymerization of catalysts using the ethylene polymerization evaluation test device, ethylene monomers are added at the top of the polymerization reactor, and ethylene gas dissolves in the dispersant under certain temperature and pressure conditions. This polymerization process differs from that of the slurry-method industrial production device, where ethylene is added from the bottom of the reactor during the polymerization reaction. Therefore, the existing slurry-method ethylene polymerization evaluation test device is inaccurate in evaluating catalyst activity and has a certain gap with the industrial production device, failing to truly reflect the catalyst's performance.

[0006] Zhang Junwei, Li Huashu, et al., in "Preparation of a Novel Catalyst for Ethylene Slurry Polymerization with High Hydrogen Sensitivity" ([J]. Synthetic Resins and Plastics, 2015, 32(1):6-9;), used a 2 L polymerization reactor for ethylene slurry polymerization. After purging with nitrogen, 1 L of n-hexane was added, stirring was started, and the required amount of 1-hexene was added. At the same time, a certain amount of TEAL hexane solution and catalyst were added. The polymerization reactor control program was started, and after the temperature was raised to the specified temperature, hydrogen and ethylene were added sequentially to the reaction pressure to start polymerization. After polymerization was completed, the ethylene supply was stopped and the temperature was lowered. The pressure was released and the material was discharged. The defects of this technology or the shortcomings of this invention are as follows: the comonomers were not mixed and were added all at once from the top of the reactor. The mixing effect of ethylene and 1-hexene was poor. The polymerization process of this evaluation test is different from that of the slurry method industrial production device. In the slurry method industrial production device, ethylene and comonomers are pre-mixed and added from the bottom of the reactor during the polymerization reaction. Therefore, the existing slurry polymerization evaluation test device is not accurate in evaluating the activity of the catalyst.

[0007] In catalyst development, evaluating the polymerization performance of the catalyst is crucial. Existing slurry polymerization evaluation devices for ethylene polymerization involve adding ethylene monomers at the top of the polymerization reactor, with ethylene gas dissolving into a dispersant under specific temperature and pressure conditions. This evaluation process differs from that of industrial slurry polymerization plants, where ethylene is added from the bottom. Furthermore, the existing evaluation devices require time to reach the set reaction pressure after initial ethylene addition, resulting in lower initial catalyst activity. Therefore, the current slurry polymerization evaluation devices are inaccurate in assessing catalyst activity, showing a discrepancy with industrial production facilities and failing to accurately reflect catalyst performance. Consequently, they cannot provide effective data support for pilot-scale polymerization process studies of the catalyst. Summary of the Invention

[0008] To address the problems of existing technologies, this invention provides an evaluation method for an ethylene-α-olefin copolymerization evaluation test apparatus. The monomers are dispersed into the slurry system from the gas outlet on the agitator at the bottom of the reactor, increasing the monomer concentration in the slurry system and enhancing the contact between the monomers and the catalyst. This more closely resembles the polymerization environment of an industrial slurry polymerization plant, allowing for the full release of catalyst activity. Using this evaluation method for ethylene-α-olefin copolymerization can accurately assess catalyst activity, providing technical support for the operation of pilot-scale polymerization plants and overcoming the shortcomings of existing technologies. Furthermore, the reaction temperature control unit of this invention is used to control the stability of the reaction temperature, preventing the high heat generated by the rapid polymerization reaction rate from affecting catalyst activity. The pressure control unit of this invention is used to control the stability of the reaction pressure and enables the rapid addition of monomers and quick adjustment to the reaction pressure at the initial stage of the reaction.

[0009] To achieve the above objectives, the present invention provides an evaluation method for an evaluation test apparatus for copolymerization of ethylene and α-olefins, comprising the following steps:

[0010] Step S1: Mix ethylene and α-olefin in an olefin mixing and gas distribution device to obtain a mixed gas for later use;

[0011] Step S2: Under a nitrogen atmosphere, add the dispersant to the polymerization reactor and use a temperature control unit to raise the temperature of the polymerization reactor to the set reaction temperature;

[0012] Step S3: Add the catalyst and molecular weight regulator to the polymerization reactor and adjust the stirring speed.

[0013] Step S4: The mixed gas obtained in step S1 is input through the gas inlet on the stirring shaft of the stirring device and transported along the hollow pipe inside the stirring shaft to the stirring paddle located at the bottom of the polymerization reactor. The mixed gas is discharged from at least one gas outlet on the stirring paddle, and the polymerization reaction begins.

[0014] Step S5: Control the reaction temperature and pressure inside the polymerization reactor through the pressure control unit and temperature control unit. Stop adding the mixed gas after the set reaction time is reached.

[0015] Step S6: Use the temperature control unit to cool down the polymerization reactor, vent the gas inside the polymerization reactor, add nitrogen to replace it, and discharge the reaction products.

[0016] In one embodiment, the pressure control unit includes at least three pipelines, each of which is equipped with a pressure regulating switch. When the difference between the set pressure and the actual pressure of the polymerization reactor is not less than 0.15 MPa, all three pressure regulating switches of the three pipelines are opened simultaneously. When the difference between the set pressure and the actual pressure of the polymerization reactor is not less than 0.1 MPa, two of the pressure regulating switches of the three pipelines are opened simultaneously. When the difference between the set pressure and the actual pressure of the polymerization reactor is not less than 0.05 MPa, one of the pressure regulating switches of the three pipelines is opened.

[0017] In one embodiment, the temperature control unit includes at least one heat-relief sleeve and a temperature control system; the heat-relief sleeve passes through the reactor lid; the temperature control system is located outside the polymerization reactor, and includes a jacket and a coil. The jacket is located on the outer surface of the polymerization reactor, and a heating medium is provided between the jacket and the outer surface of the polymerization reactor; the coil surrounds the outer surface of the polymerization reactor, and a heat-relief medium flows through the coil; when the difference between the actual temperature inside the polymerization reactor and the set temperature is greater than 2°C, the heat-relief sleeve and the temperature control system are simultaneously activated for heat relief; when the difference between the actual temperature inside the polymerization reactor and the set temperature is not greater than 2°C, the temperature control system is activated for heat relief.

[0018] In one embodiment, the stirring shaft and the stirring paddle are detachably connected; the stirring paddle is at least one of a propeller-type stirring paddle, a turbine-type stirring paddle, a paddle-type stirring paddle, a propeller-type stirring paddle, a ribbon-type stirring paddle, and a folding blade-type stirring paddle.

[0019] In one embodiment, the stirring device is further provided with a stirring motor, which is located at the upper end of the stirring shaft, and the stirring speed of the stirring device is 0-800 r / min.

[0020] In one embodiment, the polymerization reactor includes a lid and a body, and a fixing frame is provided on one side of the polymerization reactor. The fixing frame is equipped with a lifting device and a base. When the polymerization reactor is disassembled or installed, the lifting device is used to separate or combine the lid and the body.

[0021] In one embodiment, the vessel lid is further provided with a gas inlet, a venting and vacuuming port, a catalyst inlet, a pressure detection port, and a temperature detection port.

[0022] In one embodiment, the bottom of the polymerization reactor is provided with a discharge port.

[0023] In one embodiment, the ethylene polymerization evaluation test apparatus is used to evaluate the ethylene polymerization reaction catalyzed by a polyethylene catalyst in a slurry system, the slurry system including a dispersant, a catalyst, a molecular weight regulator and a polymerization monomer.

[0024] In one embodiment, the dispersant includes at least one of alkanes, aromatics, and halogenated hydrocarbons, the molecular weight regulator is hydrogen, and the polymerization monomer is ethylene.

[0025] In one embodiment, the olefin mixing and distribution device includes: a gas distribution tank, a guide ring, a distribution plate, a static mixer, an olefin feed inlet, and a circulation power unit. The gas distribution tank has a raw material inlet, a mixed gas outlet, and a circulation outlet at the top, and a circulation inlet at the bottom; the guide ring is located inside the gas distribution tank and connected to the circulation inlet at the bottom of the gas distribution tank; the distribution plate is located inside the gas distribution tank and above the guide ring; the static mixer is connected to the circulation outlet at the top of the gas distribution tank and the circulation inlet at the bottom of the gas distribution tank; the olefin feed inlet is located between the static mixer and the circulation outlet; and the circulation power unit is located between the static mixer and the circulation inlet.

[0026] In one embodiment, a chromatograph is also included, disposed at the top of the gas mixing tank.

[0027] In one embodiment, a heating device is also included, disposed inside the gas distribution tank; the heating device includes at least one of a water bath heating device, a steam heating device, an oil bath heating device, an electric heating device, and a light wave heating device.

[0028] In one embodiment, a heating device is further included, disposed on the outer wall of the gas distribution tank; the heating device includes at least one of an electric heating belt and an electric heating jacket.

[0029] In one embodiment, the system further includes a temperature detection port, a pressure detection port, and a discharge port. The temperature detection port and the pressure detection port are located at the top of the gas distribution tank, and the discharge port is located at the bottom of the gas distribution tank.

[0030] In one embodiment, the circulating power unit is a pump or a compressor.

[0031] In one embodiment, the raw material inlet is a first raw material or a nitrogen inlet, used for adding the first raw material or for nitrogen purging.

[0032] In one embodiment, the olefin inlet is a second feed inlet.

[0033] In one embodiment, the first raw material and the second raw material are α-olefins, including at least one selected from ethylene, propylene, 1-butene, 4-methyl-1-pentene, 1-hexene and 1-octene.

[0034] This invention also provides an evaluation test apparatus for the copolymerization of ethylene and α-olefins. This apparatus includes an olefin mixing and gas distribution device, a polymerization reactor, a temperature control unit, a pressure control unit, and a stirring device. The polymerization reactor is connected to the olefin mixing and gas distribution device; the temperature control unit is connected to the polymerization reactor; the pressure control unit is connected to the polymerization reactor; the stirring device includes a stirring shaft and a stirring paddle; the stirring shaft is a hollow structure with an internal gas flow channel, one end of the stirring shaft passes through the reactor lid and has a gas inlet, and the other end of the stirring shaft is connected to the stirring paddle; the stirring paddle is located at the bottom of the polymerization reactor; the stirring paddle has at least one gas outlet.

[0035] The evaluation method of the ethylene and α-olefin copolymerization evaluation test device of the present invention involves the ethylene and α-olefin comonomers being fully mixed by an olefin mixing and gas distribution device and then dispersed into the slurry system from the gas outlet on the agitator at the bottom of the polymerization reactor. This increases the concentration of the polymer monomers in the slurry system, increases the contact amount between the polymer monomers and the catalyst, and more closely resembles the polymerization environment of an industrial slurry production plant. The catalyst activity is fully released, and the reaction temperature control unit and pressure control unit significantly reduce the fluctuation of the reaction temperature and reaction pressure in the polymerization reactor. Furthermore, it enables the rapid addition of polymer monomers and rapid adjustment to the reaction pressure at the initial stage of the reaction.

[0036] This invention improves the accuracy of catalyst activity evaluation, provides fundamental data for slurry-based pilot-scale polymerization units, and can significantly improve the efficiency and reduce the cost of pilot-scale polymerization units. It has important guiding significance for the operation of slurry-based pilot-scale units, polymerization process development, and technical services for production facilities. This invention can also reduce the risks caused by unclear catalyst activity during polymerization experiments. Therefore, this invention is of great significance for accelerating the research and development of polyethylene catalysts and new products, as well as improving the quality of technical services. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of an embodiment of the ethylene-α-olefin copolymerization evaluation test apparatus of the present invention.

[0038] In the attached figures, the following labels are used:

[0039] Gas distribution tank 1

[0040] Polymerization reactor 2

[0041] Pressure control unit 3

[0042] Cyclic Power Unit 4

[0043] Distribution plate 5

[0044] Flow guide ring 6

[0045] Chromatography 7

[0046] Raw material inlet 8

[0047] Circulation outlet 9

[0048] Temperature detection port 10

[0049] Pressure detection port 11

[0050] Loop entry 12

[0051] Discharge port 13

[0052] Heating device 14

[0053] Static Mixer 15

[0054] Olefin inlet 16

[0055] Mixed gas outlet 17

[0056] Gas inlet 18

[0057] Air outlet 19

[0058] Pressure regulating switches 20, 21, 22

[0059] Stirring shaft 23

[0060] 24-inch agitator

[0061] Gas outlet 25

[0062] Cauldron cover 26

[0063] 27 cauldrons

[0064] Gas inlet 28

[0065] Vent and vacuum port 29

[0066] Catalyst inlet 30

[0067] Heat relief sleeve 31

[0068] Pressure detection port 32

[0069] Temperature detection port 33

[0070] Temperature control system 34

[0071] 35mm discharge port

[0072] Fixture 36

[0073] Lifting device 37

[0074] Base 38 Detailed Implementation

[0075] The ethylene polymerization evaluation test apparatus of the present invention will be further described below with reference to the accompanying drawings.

[0076] Please refer to Figure 1 , Figure 1 This is a schematic diagram of an embodiment of the ethylene-α-olefin copolymerization evaluation test device of the present invention. The ethylene-α-olefin copolymerization evaluation test device of the present invention includes an olefin mixing and gas distribution device, a polymerization reactor 2, a temperature control unit, a pressure control unit 3, and a stirring device.

[0077] The olefin mixing and gas distribution device of the present invention includes a gas distribution tank 1, a guide ring 6, a distribution plate 5, a static mixer 15, an olefin feed inlet 16, and a circulating power unit 4.

[0078] Gas mixing tank 1 is used to mix and distribute raw materials, including ethylene and at least one α-olefin, such as, but not limited to, propylene, 1-butene, 4-methyl-1-pentene, 1-hexene, and 1-octene. The top of gas mixing tank 1 is equipped with a gas chromatograph 7, a raw material inlet 8, a mixed gas outlet 17, a circulation outlet 9, a temperature detection port 10, and a pressure detection port 11. The bottom of gas mixing tank 1 is equipped with a circulation inlet 12 and a discharge port 13.

[0079] Raw material inlet 8 is either the first raw material or a nitrogen inlet, used for adding the first raw material or for nitrogen purging. The first raw material can be a single substance or a mixture. For example, the first raw material can be at least one of ethylene, propylene, 1-butene, 4-methyl-1-pentene, 1-hexene, and 1-octene, or it can be a mixture of at least two of ethylene, propylene, 1-butene, 4-methyl-1-pentene, 1-hexene, and 1-octene.

[0080] Mixed gas outlet 17 is the outlet for the prepared mixed gas, used to transport the mixed gas to the downstream olefin copolymerization unit or for sampling.

[0081] The circulation outlet 9 is used to output the recycled olefins to the circulation pipeline. Preferably, the circulation pipeline is provided with insulation material on the outside.

[0082] Temperature detection port 10 is used to detect the temperature of gas mixing tank 1, so as to facilitate the complete conversion of liquid olefins into gaseous state.

[0083] The pressure detection port 11 is used to detect the pressure of the gas distribution tank 1, which facilitates the control of the complete conversion of liquid olefins into gaseous state, while also meeting the pressure range of the downstream olefin copolymerization unit.

[0084] Chromatography 7 is used to measure the gas components and their content in gas mixing tank 1 online, ensuring that the obtained mixed gas meets the test requirements.

[0085] Preferably, the gas distribution tank 1 is further provided with a heating device 14, which can be disposed inside or on the outer wall of the gas distribution tank 1. When the heating device 14 is disposed inside the gas distribution tank 1, the heating device 14 includes at least one of a water bath heating device, a steam heating device, an oil bath heating device, an electric heating device, and a light wave heating device. When the heating device 14 is disposed on the outer wall of the gas distribution tank 1, the heating device 14 includes at least one of an electric heating belt and an electric heating sleeve.

[0086] The olefin inlet 16 is located between the static mixer 15 and the circulation outlet 9. The olefin inlet 16 is a second raw material inlet, which is used to add the second raw material to be mixed. The second raw material can be at least one of ethylene, propylene, 1-butene, 4-methyl-1-pentene, 1-hexene and 1-octene, and is most preferably liquid olefin.

[0087] The static mixer 15 is located between the olefin inlet 16 and the circulating power unit 4, and is used to mix the first raw material from the gas distribution tank 1 and the second raw material added by the olefin inlet 16 for the first time to obtain the first mixture.

[0088] The circulating power unit 4 is located between the static mixer 15 and the circulating inlet 12 to provide circulating power for the circulating mixed olefins. The circulating power unit 4 is, for example, but not limited to, a pump or compressor.

[0089] The circulation inlet 12 is used to input the first mixture into the gas distribution tank 1.

[0090] The discharge port 13 is used to remove residual materials or purge the gas distribution tank 1.

[0091] The guide ring 6 is located inside the gas distribution tank 1 and is connected to the circulation inlet 12 at the bottom of the gas distribution tank 1; the guide ring 6 is used to disperse the first mixture delivered by the circulation power unit 4, which can improve the mixing effect.

[0092] The distribution plate 5 is located inside the gas distribution tank 1 and above the guide ring 6. The distribution plate 5 is used to mix the first mixture dispersed by the guide ring 6. The structure of the distribution plate 5 is preferably such that the mixture is distributed in a more disordered manner to improve the mixing effect. The first mixture is dispersed by the guide ring 6 and then mixed a second time by the distribution plate 5 to obtain the second mixture.

[0093] In use, the olefin mixing and gas distribution device of the present invention first sets the temperature and pressure according to the physical properties of the raw materials. The first raw material is input into the olefin mixing and gas distribution device through the raw material inlet 8 at the top of the gas distribution tank 1. The heating device 14 heats the raw material to the set temperature. The second raw material is input into the static mixer 15 through the olefin inlet 16. The first raw material in the olefin mixing and gas distribution device is output from the circulation outlet 9 and enters the static mixer 15. The first raw material and the second raw material are mixed for the first time in the static mixer 15 to obtain a first mixture. The first mixture is input into the olefin mixing and gas distribution device through the circulation inlet 12 via the circulation power unit 4. The first mixture is dispersed by the guide ring 6 and mixed for the second time by the distribution plate 5 to obtain a second mixture. The second mixture is analyzed by chromatography 7 to test the mixing result. If the mixing result is qualified, the second mixture is output from the mixed gas outlet 17 and enters the downstream olefin polymerization device for copolymerization reaction. If the mixing result is unqualified, the second mixture is output from the circulation outlet 9 and input into the static mixer 15 for re-mixing. The circulation power unit 4 provides power for the circulation of materials.

[0094] The olefin mixing and gas distribution method of the present invention uses the above-mentioned olefin mixing and gas distribution device, and the method includes the following steps:

[0095] Step S1: Input the first raw material into the olefin mixing and gas distribution device through the raw material inlet at the top of the gas distribution tank;

[0096] Step S2: The second raw material is fed into the static mixer through the olefin feed port; the first raw material in the olefin mixing and gas distribution device is output from the circulation outlet and enters the static mixer. The first raw material and the second raw material are mixed for the first time in the static mixer to obtain the first mixture.

[0097] Step S3: The first mixture is fed into the olefin mixing and gas distribution device through the circulation inlet of the circulating power unit. The first mixture is dispersed by the guide ring and mixed a second time by the distribution plate to obtain the second mixture.

[0098] Step S4: The second mixture is tested by chromatographic analysis to determine the mixing result; if the mixing result is qualified, the second mixture is output from the mixed gas outlet and enters the downstream process; if the mixing result is unqualified, return to step S2, the second mixture is output from the circulation outlet and input into the static mixer for remixing.

[0099] The polymerization reactor 2 includes a lid 26 and a body 27. A fixing frame 36 is also provided on one side of the polymerization reactor 2. The fixing frame 36 is equipped with a lifting device 37 and a base 38. When the polymerization reactor 2 is disassembled or installed according to production needs, the lifting device 37 can be used to separate or combine the lid 26 and the body 27.

[0100] The reactor lid 26 is equipped with a gas inlet 28, a vent and vacuum port 29, a catalyst inlet 30, a pressure detection port 32, and a temperature detection port 33. The gas inlet 28 is used to add ethylene, nitrogen, and hydrogen to the polymerization reactor 2, forming the nitrogen atmosphere required for the reaction. The vent and vacuum port 29 is used for venting the gas and for vacuuming the polymerization reactor 2 during purification. The catalyst inlet 30 is used to add dispersants and catalysts for olefin polymerization. The pressure detection port 32 is used to measure the pressure of the reaction system and for pressure control; preferably, the polymerization reaction pressure is 0.5-2.0 MPa. The temperature detection port 33 is used to measure the temperature of the polymerization reaction; preferably, the polymerization reaction temperature is 70-100°C.

[0101] A temperature control unit, used to control the temperature stability inside the polymerization reactor, includes at least one heat-relief jacket 31 and a temperature control system 34. The heat-relief jacket 31 passes through the reactor lid 26 to remove heat generated during polymerization. A heat-relief medium is provided inside the jacket 31, entering from the inner tube and flowing out from the outer tube. The temperature control system 34 is located outside the polymerization reactor 2. The temperature control system 34 includes a jacket and a coil. The jacket is located on the outer surface of the polymerization reactor 2, and a heating medium is provided between the jacket and the outer surface of the polymerization reactor 2 to provide the heat required for the initial stage of the polymerization reaction. The coil surrounds the outer surface of the polymerization reactor 2, and a heat-relief medium flows through the coil.

[0102] When the difference between the actual temperature inside the polymerization reactor 2 and the set temperature is greater than 2°C, the heat dissipation sleeve 31 and the temperature control system 34 are simultaneously activated for heat dissipation. When the difference between the actual temperature inside the polymerization reactor 2 and the set temperature is not greater than 2°C, the temperature control system 34 is activated for heat dissipation. Using the ethylene polymerization evaluation test apparatus of this invention, the polymerization temperature can be controlled stably within ±2°C.

[0103] The pressure control unit 3 is used to control the pressure stability inside the polymerization reactor. It includes at least three pipelines, all of which are connected to the mixed gas outlet 17 of the olefin mixing and gas distribution device. Each of the three pipelines is equipped with a pressure regulating switch 20, 21, and 22. In this embodiment, pressure regulating switch 20 is connected to the gas outlet 19, which is connected to the gas inlet 28. Pressure regulating switches 21 and 22 are both connected to the gas inlet 18 of the stirring device.

[0104] When the difference between the set pressure and the actual pressure of the polymerization reactor 2 is not less than 0.15 MPa, the three pressure regulating switches 20, 21, and 22 of the three pipelines are opened simultaneously to quickly add reaction gas to the set pressure; when the difference between the set pressure and the actual pressure of the polymerization reactor 2 is not less than 0.1 MPa, two of the pressure regulating switches of the three pipelines are opened simultaneously, for example, pressure regulating switches 21 and 22; when the difference between the set pressure and the actual pressure of the polymerization reactor 2 is not less than 0.05 MPa, one of the pressure regulating switches of the three pipelines is opened, for example, pressure regulating switch 22.

[0105] The stirring device includes a stirring shaft 23 and a stirring paddle 24. The stirring shaft 23 is a hollow structure with an internal gas flow channel. One end of the stirring shaft 23 passes through the lid 26 of the polymerization reactor 2 and has a gas inlet 18. The other end of the stirring shaft 23 is connected to the stirring paddle 24. The stirring paddle 24 is located at the bottom of the polymerization reactor 2. The stirring paddle 24 has at least one gas outlet 25. The present invention does not particularly limit the number of gas outlets 25. The number of gas outlets 25 can be, for example, but not limited to, 2-6 or 7-15. Ethylene enters through the gas inlet 18 and is uniformly dispersed into the slurry system through the gas outlets 25 on the stirring paddle 24 at the bottom of the polymerization reactor 2, making the movement state of the ethylene monomer in the polymerization reactor 2 closer to the movement state of ethylene in the polymerization process of industrial production equipment.

[0106] Preferably, the stirring shaft 23 and the stirring paddle 24 are designed to be detachably connected for easy cleaning; the stirring paddle 4 is at least one of the following: a propeller-type stirring paddle, a turbine-type stirring paddle, a paddle-type stirring paddle, a propeller-type stirring paddle, a ribbon-type stirring paddle, and a folding blade-type stirring paddle.

[0107] Preferably, the stirring device is also equipped with a stirring motor, which is located at the upper end of the stirring shaft 23, and the stirring speed of the stirring device is 0-800 r / min.

[0108] The ethylene polymerization evaluation test apparatus of the present invention is used to evaluate the ethylene polymerization reaction catalyzed by polyethylene catalyst in a slurry system. The slurry system includes a dispersant, a catalyst, a molecular weight regulator, and a monomer.

[0109] Preferably, the dispersant includes at least one of alkanes, aromatics, and halogenated hydrocarbons, the molecular weight regulator is hydrogen, and the polymerization monomer is ethylene.

[0110] The evaluation method of the ethylene polymerization evaluation test apparatus of the present invention includes the following steps:

[0111] Step S1: Under a nitrogen atmosphere, add the dispersant to the polymerization reactor and use a temperature control unit to raise the temperature of the polymerization reactor to the set reaction temperature;

[0112] Step S2: Add the catalyst and molecular weight regulator to the polymerization reactor and adjust the speed of the stirring device;

[0113] Step S3: The mixed gas is input through the gas inlet on the stirring shaft of the stirring device and transported along the hollow pipe inside the stirring shaft to the stirring paddle located at the bottom of the polymerization reactor. The mixed gas is discharged from at least one gas outlet on the stirring paddle, and the polymerization reaction begins.

[0114] Step S4: Control the reaction temperature and pressure inside the polymerization reactor through the pressure control unit and temperature control unit. Stop adding mixed gas after the set reaction time is reached.

[0115] Step S5: Use the temperature control unit to cool down the polymerization reactor, vent the gas inside the polymerization reactor, add nitrogen to replace it, and discharge the reaction products.

[0116] The evaluation method of the ethylene polymerization evaluation test device of the present invention can also be described in detail as follows: Nitrogen gas is added to the polymerization reactor 2 through the gas inlet 28 until the pressure is 0.3 MPa; the polymerization reactor 2 is evacuated through the vent and vacuum port 29, and the evacuation is repeated 8 to 10 times; then nitrogen gas is introduced until the pressure is 0 MPa; the vent and vacuum port 29 is opened, and the dispersant is added to the polymerization reactor 2 through the catalyst inlet 30; the vent and vacuum port 29 is closed, and the temperature of the polymerization reactor 2 is raised to the set reaction temperature using the temperature control system 34; a certain amount of co-catalyst alkylaluminum and main catalyst are added to the polymerization reactor 2 through the catalyst inlet 30; the speed of the stirring device is adjusted to 100-400 rpm. r / min; add the required hydrogen gas through the gas inlet 28, and add the mixed gas to the set reaction pressure through the pressure control unit 3 to start the polymerization reaction; use the pressure control unit 3 and the temperature control unit to control the reaction temperature and reaction pressure in the polymerization reactor 2, and stop adding the mixed gas after the set reaction time is reached; use the temperature control system 34 and the heat removal sleeve 31 to reduce the temperature in the polymerization reactor 2 to 20°C, open the venting and vacuum port 29 to vent the gas in the polymerization reactor 2, add nitrogen gas to replace it 3-5 times, open the discharge port 35 to discharge the reaction product.

[0117] The evaluation method of the ethylene-α-olefin copolymerization evaluation test apparatus of the present invention includes the following steps:

[0118] Step S1: Mix ethylene and α-olefin in an olefin mixing and gas distribution device to obtain a mixed gas for later use;

[0119] Step S2: Under a nitrogen atmosphere, add the dispersant to the polymerization reactor and use a temperature control unit to raise the temperature of the polymerization reactor to the set reaction temperature;

[0120] Step S3: Add the catalyst and molecular weight regulator to the polymerization reactor and adjust the stirring speed.

[0121] Step S4: The mixed gas obtained in step S1 is input through the gas inlet on the stirring shaft of the stirring device and transported along the hollow pipe inside the stirring shaft to the stirring paddle located at the bottom of the polymerization reactor. The mixed gas is discharged from at least one gas outlet on the stirring paddle, and the polymerization reaction begins.

[0122] Step S5: Control the reaction temperature and pressure inside the polymerization reactor through the pressure control unit and temperature control unit. Stop adding the mixed gas after the set reaction time is reached.

[0123] Step S6: Use the temperature control unit to cool down the polymerization reactor, vent the gas inside the polymerization reactor, add nitrogen to replace it, and discharge the reaction products.

[0124] The following provides a detailed description of the embodiments of the present invention: These embodiments are implemented based on the technical solution of the present invention, and provide detailed implementation methods and processes. However, the scope of protection of the present invention is not limited to the following embodiments. Experimental methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions.

[0125] Source of raw materials or equipment:

[0126]

[0127] Evaluation and analysis methods:

[0128] Polymerization activity was calculated using the following method:

[0129]

[0130] The unit of polymerization activity is g PE / (g Cat•h).

[0131] Example 1:

[0132] Ethylene and propylene are added to the gas mixing tank through the raw material inlet and olefin inlet, respectively. A mixed gas is prepared at 30°C according to the molar ratio of ethylene to propylene of 49 / 1. The mixed gas is then ready for use.

[0133] Nitrogen gas was added to the 2L polymerization reactor through the gas inlet until the gauge pressure reached 0.3 MPa. The reactor was then evacuated through the vent and vacuum ports, repeating this process eight times. Nitrogen gas was then introduced until the gauge pressure reached 0 MPa. The vent was opened, and 0.8 L of hexane (dispersant) was added to the polymerization reactor through the catalyst inlet. The vent was closed, and the stirring speed was adjusted to 200 rpm. The temperature of the polymerization reactor was raised to 80°C using the temperature control system. The stirring speed was reduced to 50 rpm, and 0.2 L of hexane (dispersant) was used to inject the co-catalyst triethylaluminum and 10 mg of Zn catalyst into the polymerization reactor through the catalyst feed port. The triethylaluminum addition ratio was Al / Ti (molar) = 100. The stirring speed was then adjusted to 200 rpm. The reaction rate was increased by r / min. Hydrogen gas at 0.2 MPa was added through the gas inlet, followed by a mixture of ethylene and propylene gas at 1.0 MPa to reach the reaction pressure, initiating the polymerization reaction. After reacting for 2 hours under the reaction pressure, the addition of ethylene was stopped. The polymerization reactor was cooled to 20°C using a temperature control system. The vent was opened to release the gas inside the reactor, and nitrogen was added to purge five times. The reaction product was then released through the outlet. After separating the dispersant hexane, the polymer product was obtained. The experimental results are shown in Table 1.

[0134] Example 2:

[0135] The ZN catalyst was evaluated using the same method as in Example 1, except that the mixed gas was prepared at 30°C with an ethylene to propylene molar ratio of 48 / 2. The specific experimental conditions and results are shown in Table 1.

[0136] Example 3:

[0137] The ZN catalyst was evaluated using the same method as in Example 1, except that the mixed gas was prepared at 60°C with a molar ratio of ethylene to 1-butene of 49 / 1. The specific experimental conditions and results are shown in Table 1.

[0138] Example 4:

[0139] The ZN catalyst was evaluated using the same method as in Example 1, except that the mixed gas was prepared at 60°C with a molar ratio of ethylene to 1-butene of 48 / 2. The specific experimental conditions and results are shown in Table 1.

[0140] Example 5:

[0141] The ZN catalyst was evaluated using the same method as in Example 1, except that the mixed gas was prepared at 80°C with a molar ratio of ethylene to 1-hexene of 49 / 1. The specific experimental conditions and results are shown in Table 1.

[0142] Example 6:

[0143] The ZN catalyst was evaluated using the same method as in Example 1, except that the mixed gas was prepared at 80°C with a molar ratio of ethylene to 1-hexene of 48 / 2. The specific experimental conditions and results are shown in Table 1.

[0144] Comparative Example 1:

[0145] The ZN catalyst was evaluated using the same method as in Example 1, except that the polymerization reactor structure of the existing slurry polymerization evaluation test apparatus was different. The stirring shaft in this comparative example's polymerization reactor did not have a hollow structure, and the stirring paddle did not have a gas outlet. The catalyst was added from the top of the polymerization reactor and dissolved in the dispersant under the set reaction temperature and pressure conditions before contacting the catalyst. The comonomer was added all at once through the monomer inlet. Furthermore, the pressure control unit of this polymerization reactor used a single pipeline. Unmixed ethylene and propylene were added separately from the top of the polymerization reactor. Specific experimental conditions and results are shown in Table 1.

[0146] Comparative Example 2:

[0147] The ZN catalyst was evaluated using the same method as in Comparative Example 1, except that the molar ratio of ethylene to propylene was 48 / 2. Specific experimental conditions and results are shown in Table 1.

[0148] Comparative Example 3:

[0149] The ZN catalyst was evaluated using the same method as in Comparative Example 1, except that ethylene and 1-butene were used. The specific experimental conditions and results are shown in Table 1.

[0150] Comparative Example 4:

[0151] The ZN catalyst was evaluated using the same method as in Comparative Example 1, except that ethylene and 1-butene were used, with a molar ratio of ethylene to 1-butene of 48 / 2. The specific experimental conditions and results are shown in Table 1.

[0152] Comparative Example 5:

[0153] The ZN catalyst was evaluated using the same method as in Comparative Example 1, except that ethylene and 1-hexene were used. The specific experimental conditions and results are shown in Table 1.

[0154] Comparative Example 6:

[0155] The ZN catalyst was evaluated using the same method as in Comparative Example 1, except that ethylene and 1-hexene were used, with a molar ratio of 48 / 2. The specific experimental conditions and results are shown in Table 1.

[0156] Table 1. Experimental conditions and results of the examples and comparative examples.

[0157]

[0158] As shown in Table 1, compared with the evaluation method of the existing ethylene slurry polymerization evaluation test device, the mixed gas of the present invention is input from the bottom of the polymerization reactor. Under the same ethylene to α-olefin molar ratio, the polymerization activity of the catalyst of the present invention is improved. The evaluation method of the ethylene and α-olefin copolymerization evaluation test device of the present invention more accurately evaluates the polymerization activity of polyethylene catalyst, which can provide basic data for the operation of slurry polyethylene pilot-scale polymerization device, and can effectively improve the utilization efficiency and operation safety of pilot-scale polymerization device.

[0159] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements without departing from the present invention, and these improvements should also be considered within the scope of protection of the present invention.

Claims

1. An evaluation method for an ethylene and α-olefin copolymerization evaluation test apparatus, characterized by, Includes the following steps: Step S1: Mix ethylene and α-olefin in an olefin mixing and gas distribution device to obtain a mixed gas for later use; Step S2: Under a nitrogen atmosphere, add the dispersant to the polymerization reactor and use a temperature control unit to raise the temperature of the polymerization reactor to the set reaction temperature; Step S3: Add the catalyst and molecular weight regulator to the polymerization reactor and adjust the stirring speed. Step S4: The mixed gas obtained in step S1 is input through the gas inlet on the stirring shaft of the stirring device and transported along the hollow pipe inside the stirring shaft to the stirring paddle located at the bottom of the polymerization reactor. The mixed gas is discharged from at least one gas outlet on the stirring paddle, and the polymerization reaction begins. Step S5: Control the reaction temperature and pressure inside the polymerization reactor through the pressure control unit and temperature control unit. Stop adding the mixed gas after the set reaction time is reached. Step S6: Use the temperature control unit to cool down the polymerization reactor, vent the gas inside the polymerization reactor, add nitrogen to replace it, and discharge the reaction products; The olefin mixing and gas distribution device includes: a gas distribution tank, a guide ring, a distribution plate, a static mixer, an olefin feed inlet, a circulating power unit, and a heating device. The top of the gas mixing tank is provided with a raw material inlet, a mixed gas outlet, a circulation outlet, and a chromatograph, and the bottom is provided with a circulation inlet. The first raw material is input into the olefin mixing gas mixing device through the raw material inlet at the top of the gas mixing tank. The flow guide ring is located inside the gas distribution tank and is connected to the circulation inlet at the bottom of the gas distribution tank; The distribution plate is disposed inside the gas distribution tank and located above the flow guide ring; The static mixer is connected to the circulation outlet at the top of the gas distribution tank and the circulation inlet at the bottom of the gas distribution tank; The olefin inlet is located between the static mixer and the circulation outlet. The second raw material is fed into the static mixer through the olefin inlet. The first raw material is output from the circulation outlet and enters the static mixer. The first raw material and the second raw material are mixed for the first time in the static mixer to obtain a first mixture. The circulating power unit is located between the static mixer and the circulating inlet; The heating device is located inside or on the outer wall of the gas distribution tank; The first mixture is fed into the olefin mixing and distribution device through the circulation inlet via the circulation power unit. The first mixture is dispersed by the guide ring and mixed a second time by the distribution plate to obtain the second mixture. The second mixture is tested by chromatographic analysis to determine the mixing result. If the mixing result is qualified, the second mixture is output from the mixed gas outlet and enters the downstream process. If the mixing result is unqualified, the second mixture is output from the circulation outlet and input into the static mixer for re-mixing.

2. The evaluation method of the ethylene and α-olefin copolymerization evaluation test apparatus according to claim 1, characterized by, When the heating device is located inside the gas distribution tank, the heating device includes at least one of a water bath heating device, a steam heating device, an oil bath heating device, an electric heating device, and a light wave heating device.

3. The evaluation method of the ethylene and α-olefin copolymerization evaluation test apparatus according to claim 1, characterized by, When the heating device is located on the outer wall of the gas distribution tank, the heating device includes at least one of an electric heating belt and an electric heating sleeve.

4. The evaluation method for the ethylene-α-olefin copolymerization evaluation test apparatus according to claim 1, characterized in that, It also includes a temperature detection port, a pressure detection port, and a discharge port. The temperature detection port and the pressure detection port are located at the top of the gas distribution tank, and the discharge port is located at the bottom of the gas distribution tank.

5. The evaluation method for the ethylene-α-olefin copolymerization evaluation test apparatus according to claim 1, characterized in that, The circulating power unit is a pump or a compressor.

6. The evaluation method for the ethylene-α-olefin copolymerization evaluation test apparatus according to claim 1, characterized in that, The raw material inlet is either the first raw material inlet or the nitrogen inlet, used for adding the first raw material or for nitrogen purging.

7. The evaluation method for the ethylene-α-olefin copolymerization evaluation test apparatus according to claim 1, characterized in that, The olefin inlet is the second raw material inlet.

8. The evaluation method for the ethylene-α-olefin copolymerization evaluation test apparatus according to claim 1, characterized in that, The pressure control unit includes at least three pipelines, each equipped with a pressure regulating switch. When the difference between the set pressure and the actual pressure of the polymerization reactor is not less than 0.15 MPa, all three pressure regulating switches of the three pipelines are activated simultaneously. When the difference between the set pressure and the actual pressure of the polymerization reactor is not less than 0.1 MPa, two of the pressure regulating switches of the three pipelines are activated simultaneously. When the difference between the set pressure and the actual pressure of the polymerization reactor is not less than 0.05 MPa, one of the pressure regulating switches of the three pipelines is activated.

9. The evaluation method for the ethylene-α-olefin copolymerization evaluation test apparatus according to claim 1, characterized in that, The polymerization reactor includes a lid and a body; the temperature control unit includes at least one heat-relief sleeve and a temperature control system; the heat-relief sleeve passes through the lid; the temperature control system is located outside the polymerization reactor, and includes a jacket and a coil; the jacket is located on the outer surface of the polymerization reactor, and a heating medium is provided between the jacket and the outer surface of the polymerization reactor; the coil surrounds the outer surface of the polymerization reactor, and a heat-relief medium flows through the coil; when the difference between the actual temperature inside the polymerization reactor and the set temperature is greater than 2°C, the heat-relief sleeve and the temperature control system are simultaneously activated for heat relief; when the difference between the actual temperature inside the polymerization reactor and the set temperature is not greater than 2°C, the temperature control system is activated for heat relief.

10. The evaluation method of the ethylene-α-olefin copolymerization evaluation test apparatus according to claim 1, characterized in that, The stirring shaft and the stirring blade are detachably connected; the stirring blade is at least one of the following: a propeller-type stirring blade, a turbine-type stirring blade, a paddle-type stirring blade, a propeller-type stirring blade, a ribbon-type stirring blade, and a folding blade stirring blade.

11. The evaluation method of the ethylene-α-olefin copolymerization evaluation test apparatus according to claim 1, characterized in that, The stirring device is also equipped with a stirring motor, which is located at the upper end of the stirring shaft, and the stirring speed of the stirring device is 0-800 r / min.

12. The evaluation method of the ethylene-α-olefin copolymerization evaluation test apparatus according to claim 9, characterized in that, The polymerization reactor is also provided with a fixed frame on one side, and the fixed frame is provided with a lifting device and a base; when the polymerization reactor is disassembled or installed, the lifting device is used to separate or merge the reactor cover with the reactor body.

13. The evaluation method of the ethylene-α-olefin copolymerization evaluation test apparatus according to claim 12, characterized in that, The reactor lid is also equipped with a gas inlet, a venting and vacuuming port, a catalyst inlet, a pressure detection port, and a temperature detection port.

14. The evaluation method for the ethylene-α-olefin copolymerization evaluation test apparatus according to claim 1, characterized in that, The bottom of the polymerization reactor is provided with a discharge port.

15. The evaluation method for the ethylene-α-olefin copolymerization evaluation test apparatus according to claim 1, characterized in that, The ethylene-α-olefin copolymerization evaluation test device is used to evaluate the polyethylene catalyst-catalyzed ethylene polymerization reaction in a slurry system, wherein the slurry system includes a dispersant, a catalyst, a molecular weight regulator, and a polymerization monomer.

16. The evaluation method for the ethylene-α-olefin copolymerization evaluation test apparatus according to claim 15, characterized in that, The dispersant includes at least one of alkanes, aromatics, and halogenated hydrocarbons, the molecular weight regulator is hydrogen, and the polymerization monomer is ethylene.

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