An apparatus and method for olefin solution polymerization

Abstract

The application discloses a device and a method for olefin solution polymerization, and the device is a high-pressure polymerization kettle which comprises a shell, a stirring shaft arranged in the shell, a stirring motor connected with the upper end of the stirring shaft and extending out of the shell, and a stirrer connected with the lower end of the stirring shaft; the shell comprises an outer shell and an inner liner, heating coils and cooling coils are arranged on the inner liner, the heating coils and the cooling coils are in double-helix structures and are spirally wound from top to bottom around the inner liner, the heating coils and the cooling coils are cantilever floating coils, the heating coils comprise a heat medium inlet located at the upper portion and a heat medium outlet located at the lower portion, and the cooling coils comprise a cooling medium inlet located at the lower portion and a cooling medium outlet located at the upper portion. The device can realize accurate control of the temperature in the kettle and prevent temperature overshoot and violent polymerization.

Description

Technical Field

[0001] This invention belongs to the field of chemical equipment technology, specifically relating to an apparatus and method for olefin solution polymerization. Background Technology

[0002] Polyolefin elastomers, abbreviated as POE, refer to random copolymer elastomers produced by polymerizing ethylene and high-carbon α-olefins using metallocene catalysts. These elastomers exhibit a certain degree of crystallinity, a narrow molecular weight range, and a relatively low density. POE typically refers to ethylene-octene copolymer elastomers with an octene mass fraction greater than 20%. These elastomers have good compatibility with polyolefins and offer high cost-effectiveness, thus they are widely used in automotive, footwear, wire and cable, packaging, polymer modification, and medical fields.

[0003] Currently, only a handful of companies worldwide possess the complete technology and proprietary catalysts to produce POE, including Dow Chemical, ExxonMobil, Mitsui Chemicals, LG Chem, and SK Chem in the United States. Due to high technological barriers, intellectual property limitations, and raw material constraints, domestic production has not yet been achieved.

[0004] In pilot-scale or intermediate-scale polymerization of POE using the olefin solution polymerization process, as ethylene / 1-octene polymerizes under the action of a metallocene catalyst, the viscosity of the reaction system rapidly increases from 10 cp at the inlet to 1000 cp at the outlet, causing a rapid decrease in the mass and heat transfer rates within the polymerization reactor. Therefore, it is necessary to develop a specially structured polymerization reactor, combined with process control, to enhance the mass and heat transfer rates of the reactor and improve the flow properties of the solution to meet the requirements of the polymerization process. The backmixing process in the reactor offers high operational flexibility, flexible agitator combinations, guaranteed and adjustable input power, and good dispersion of catalyst and monomer within the reactor, making it ideal for high-viscosity system reactions.

[0005] In the polymerization reaction, the pressure inside the reactor is 4.0–4.5 MPa. Pre-dissolved ethylene / 1-octene reaction feedstock is introduced, and when a certain temperature is reached inside the reactor, the catalyst is continuously introduced. Due to the high activity of the metallocene catalyst, as the reaction proceeds, the comonomers polymerize and release a large amount of heat, causing the system temperature to rise rapidly. Traditional batch reactors control the reaction rate and thus the reaction temperature by adjusting the ethylene feed rate and the amount of catalyst added during the reaction. Therefore, it is difficult to control the stability of the reaction temperature, which leads to a deterioration in the product's transparency and other properties. At the same time, it increases the viscosity of the product, making it easy to clog pipelines and hindering the discharge of materials.

[0006] Patent CN107670610A discloses a chemical machinery system with a magnetically torque-adjustable reactor. The first reactor is an electromagnetically driven reactor with adjustable magnetic torque. Its agitator includes a magnetic actuator, a vertical stirring shaft, and a vertical stirring paddle. The vertical stirring paddle is mounted on the vertical stirring shaft, and the magnetic actuator is connected to the vertical stirring shaft to drive its rotation, thereby achieving stirring. This invention patent's chemical machinery system with a magnetically torque-adjustable reactor uses magnetic drive to achieve complete static sealing, zero leakage of the working container, and stable operation of the equipment. It also effectively reduces vibration transmission. Multiple reactors, air inlets, feed inlets, and check valves are used to process various materials. This invention relates to chemical machinery systems, particularly to a reactor with a stirring structure, but it does not explicitly describe the application of such a reactor in the field of solution-based olefin polymerization, especially how to control the stability of reaction pressure and temperature, thus having certain limitations.

[0007] Patent CN214553409U discloses an olefin polymerization apparatus. The packing box is equipped with multiple circular discharge channels, the depth of which is the same as the thickness of the packing box. A hydraulic push rod is fixedly connected to the packing box inside. A baffle is fixedly connected to the lower end of the hydraulic push rod. A baffle tube is fixedly connected to the baffle tube inside the baffle. A storage tube with a circular discharge trough is located inside the storage tube, the thickness of which is the same as the depth of the discharge trough. The storage tube and the baffle tube are fitted together. This utility model patent solves the problem in the prior art where the material floats on the liquid surface after feeding, hindering polymerization and improving reaction efficiency. The shortcomings of this technology are that the device does not have an air inlet and a spare port on the reactor lid, making it impossible to maintain the polymerization reaction pressure. In addition, the solution olefin polymerization process requires a high reaction temperature, and the device does not have a temperature control system, so it cannot guarantee the reaction temperature. Therefore, the device is not very practical, but it has some reference value.

[0008] Patent CN 213556970U discloses an olefin polymerization evaluation device. The device includes a reactor and a reactor lid. An elastic sealing ring is bonded to the bottom of the lid, and the bottom of the elastic sealing ring is in movable contact with the top of the reactor. Fixing blocks are fixedly connected to both sides of the lid, with the sides of the two fixing blocks facing away from each other having an inclined cross-section and a slot. A sleeve is movably fitted onto the reactor, and the sleeve is threadedly fixed to the reactor. This utility model patent has a reasonable design, is easy to operate, and facilitates quick installation and disassembly of the lid and reactor, improving assembly and disassembly efficiency. It also allows for easy adjustment of the sealing performance between the lid and reactor according to actual needs, improving the sealing performance and extending the service life of the elastic sealing ring, thus meeting usage requirements and being beneficial to use. The shortcomings of this technology are that although the utility model patent has the characteristics of good sealing and strong pressure holding capacity, it does not clearly define the stirring device, temperature control system, and feeding and discharging issues. It does not take into account the reaction parameters during olefin polymerization, including reaction pressure, temperature, stirring method, etc., which are somewhat different from industrial production equipment and cannot reflect the true activity of the catalyst.

[0009] Patent CN1210967A discloses a swirl floating coil heat exchanger, which is a heat exchange device consisting of a heating tank, a coil assembly, a riser, a positioning pin, a swirl inlet, and a resonant spring. The heated medium enters the tank cavity through the swirl inlet, and the cantilevered coil assembly is supported and fixed by the resonant spring. This device only has a coil assembly for introducing hot steam and cannot regulate the temperature of the medium inside the tank. Summary of the Invention

[0010] The purpose of this invention is to provide an apparatus for olefin solution polymerization to solve the problem of untimely temperature control during the polymerization reaction.

[0011] Another object of the present invention is to provide a method for solution polymerization of olefins.

[0012] To achieve the above objectives, the present invention provides an apparatus for olefin solution polymerization. The apparatus is a high-pressure polymerization reactor, which includes a shell, a stirring shaft inside the shell, the upper end of the stirring shaft extending out of the shell and connected to a stirring motor, and a stirrer connected to the lower end of the stirring shaft. The shell includes an outer shell and an inner liner. A heating coil and a cooling coil are provided on the inner side of the liner. The heating coil and the cooling coil are arranged in a double helix structure and spirally wound around the liner from top to bottom. Both the heating coil and the cooling coil are cantilevered floating coils. The heating coil includes a heat medium inlet at the top and a heat medium outlet at the bottom. The cooling coil includes a coolant inlet at the bottom and a coolant outlet at the top.

[0013] The apparatus for olefin solution polymerization according to the present invention has at least two heat medium outlets, one located at the lower part of the heating coil and the other located at the middle part of the heating coil.

[0014] The apparatus for olefin solution polymerization described in this invention has at least two refrigerant outlets, one located at the top of the cooling coil and the other located in the middle of the cooling coil.

[0015] The apparatus for olefin solution polymerization of the present invention has an inner diameter of 10-20 mm for the heating coil and a spacing of 20-30 mm between two adjacent heating coils.

[0016] The apparatus for olefin solution polymerization of the present invention has an inner diameter of 10-15 mm for the cooling coil and a spacing of 10-20 mm between two adjacent cooling coils.

[0017] The apparatus for olefin solution polymerization described in this invention has a spacing of 3 to 5 mm between adjacent cooling coils and heating coils.

[0018] The apparatus for olefin solution polymerization described in this invention includes a high-pressure nitrogen inlet, a catalyst inlet, a raw material inlet, a lamp aperture, a high-pressure sight glass, a temperature detection port, and a high-pressure sealing shut-off valve at the top of the housing. This invention does not specify the exact dimensions and design standards of the high-pressure nitrogen inlet, catalyst inlet, raw material inlet, lamp aperture, high-pressure sight glass, temperature detection port, and high-pressure sealing shut-off valve. Those skilled in the art can adjust these dimensions according to actual conditions. Preferably, the inner diameter of the high-pressure nitrogen inlet is 3–5 mm, the inner diameter of the raw material inlet is 15–20 mm, the inner diameter of the catalyst inlet is 3–5 mm, there are two spare ports with an inner diameter of 15 mm, the lamp aperture is circular and made of stainless steel, and the high-pressure sight glass is a flange sight glass used in conjunction with the lamp aperture. The maximum operating pressure is 25 MPa, and the allowable medium temperature is -30 to 200°C. The sight glass is made of tempered borosilicate glass with a color temperature difference of 180℃. Its dimensions are: nominal diameter 50mm, height 10-15mm, and it is secured with six M12 studs. The lamp hole and high-pressure sight glass facilitate observation of the reaction and stirring of materials inside the vessel, as well as verification of cleanliness after cleaning. The temperature sensing port, with a height of 800mm-2300mm, is used to insert thermocouples.

[0019] In this invention, the stirring motor is a three-phase AC induction motor, employing frequency conversion stirring with a maximum speed of 2500 r / min, a minimum speed of 100 r / min, and a power of 400 W. The stirring shaft has a length of 800 mm to 2300 mm and a diameter of 10 to 15 mm. The stirrer is a three-layer paddle stirrer, composed of blades, a key, a shaft collar, and a vertical shaft. The diameter of the paddle stirrer is taken as 1 / 3 to 2 / 3 of the inner diameter D of the reactor. Each layer of paddles has two blades, which are folded blades with θ = 45° and dimensions of d / D = 0.4 to 0.9, b / d = 0.2 to 0.3, and Bn = 2. The operating conditions are: n = 100 r / min to 600 r / min, v = 1 to 6 m / s, and the commonly used medium viscosity range is 10 to 50 Pa / s. (Where, n - rotational speed; v - blade tip speed; Bn - number of blades; d - inner diameter of the agitator; D - inner diameter of the container; θ - blade angle).

[0020] The apparatus for olefin solution polymerization described in this invention includes a temperature detection port, a high-pressure sealing ball valve, and a discharge port at the bottom of the shell. The specific dimensions of the discharge port are not specifically limited in this invention, but a preferred size is an inner diameter of 15mm-30mm, used for discharging materials after the reaction is complete.

[0021] The apparatus for olefin solution polymerization described in this invention includes a high-pressure polymerization reactor that is an open reactor, comprising a reactor body, an upper head, and a lower head. The reactor body is connected to the upper and lower heads via quick-opening ring flanges. More specifically, the reactor body is cylindrical, made of high-temperature resistant stainless steel (SUS304 or SUS310L), with a volume of 1000–4000 ml, a pressure resistance of 3–10 MPa, and is sealed using a sanitary mechanical seal. The reactor is supported by a lug-type support. The reactor body wall thickness is 10–29 mm, and the height is 1000–2500 mm. The lining material is S30408, with a wall thickness of 5–10 mm and a length-to-diameter ratio of 5–12.5. The inner liner is designed with a maximum thickness of 10mm and a minimum thickness of 5mm, an inner diameter of 150mm, a maximum pressure of 9MPa, and a maximum temperature of 200℃. The inner liner undergoes high-precision polishing to reduce its surface roughness, with a polishing degree of 0.4~0.6μm.

[0022] The apparatus for olefin solution polymerization described in this invention has an insulation layer on the outside of the housing.

[0023] In the apparatus for olefin solution polymerization described in this invention, the heating coil or cooling coil located at the bottom is 120-150 mm from the bottom of the reactor.

[0024] The apparatus for olefin solution polymerization of the present invention includes an internal thermocouple installed inside the temperature detection port. The contacts of the thermocouple tube are located inside the lower part of the high-pressure polymerization reactor.

[0025] To achieve the above objectives, the present invention also provides a method for olefin solution polymerization using the aforementioned apparatus, comprising the following steps: introducing nitrogen gas into a high-pressure reactor, then introducing a heating medium through the heating medium inlet of a heating coil to heat the high-pressure reactor, then introducing reactants and a catalyst, and introducing a cooling medium through the cooling medium inlet of a cooling coil, the cooling medium flowing from bottom to top to deheat the reactants; maintaining a stable temperature of the reaction system by adjusting the flow rates of the heating and cooling medium during the reaction; stopping the flow of the heating medium and increasing the flow rate of the cooling medium after the reaction is completed, and discharging the material after the reaction system has cooled down.

[0026] When the device of this invention is used for olefin solution polymerization, a heat medium (steam, high-temperature hot water, etc.) is introduced into the heating coil. As the heat medium flows into the heating coil, due to the small flow area of ​​the tube, the heat medium flows at a high speed, driving the coil to vibrate at a low amplitude and high frequency, which disrupts the laminar heat transfer layer between the heating coil and the liquid, and enhances convective heat transfer. At the same time, due to the scouring effect of the water flow, the tube can be cantilevered and floats freely, expanding and contracting freely, so it is not easy for scale to form. If a small amount of scale accumulates during long-term use, it can be automatically removed through the expansion of the tube. Therefore, the heat exchange capacity does not decrease with long-term use, and the effect is good. Intelligent flow meters can be installed at the steam inlet and refrigerant inlet to control the stability of the reaction temperature by adjusting the flow rate of the heating and cooling media. To ensure temperature stability, the heating and cooling coils should be divided into at least two sections, or even more. Adjusting the flow rate of the heating and cooling media allows for precise temperature control, achieving stable temperature control during polymerization, rapid heat removal, and improved mass transfer efficiency within the reactor. During the reaction, a stirring motor above the reactor drives the stirring rod and impeller to mix the raw materials, and the polymerization reaction proceeds under the catalysis of the catalyst. External temperature control can be used during the polymerization reaction to control the flow rate of the heating and cooling media in real time, maintaining a stable reaction temperature within the reactor. The high-density distribution of heating and cooling coils and the external intelligent flow program enable precise temperature control within the reactor, preventing temperature runaway and rapid polymerization.

[0027] The solvents required for the polymerization reaction include: Ⅰ: Nonpolar hydrocarbon solvents and haloalkanes (weakly electrophilic solvents): n-hexane, n-octane, cyclohexane, toluene, benzene, carbon tetrachloride, chloroform, chlorobenzene, carbon disulfide, dichloroethane. Ⅱ: Ethers, aldehydes, ketones, esters, amides, and amines (electron-donating solvents): diethyl ether, ethyl acetate, tetrahydrofuran, butyraldehyde, butanone, acetaldehyde, cyclohexanone, acetone, pyridine, dimethylformamide. Ⅲ: Alcohols, phenols, nitro acids, sulfonic acids, and carboxylic acids (strongly electron-donating or strong hydrogen-bonding solvents): hexanol, n-pentanol, n-butanol, n-propanol, m-cresol, acetonitrile, ethanol, acetic acid, formic acid, methanol, phenol, water, sulfuric acid.

[0028] The comonomers required for the polymerization reaction are ethylene and α-olefins (1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, etc.).

[0029] The polymerization reaction conditions are as follows: reaction pressure: 2-6 MPa, reaction temperature: 80-200℃, feeding method: continuous feeding, and feeding rate: 3000ml-20000ml per hour.

[0030] The catalyst required for the polymerization reaction is a Ziegler-Natta catalyst or a metallocene catalyst (with a group IVB transition metal (such as Ti, Zr, Hf) element complex as the main catalyst and an alkylaluminoxane (such as MAO) or organoboronide as the co-catalyst).

[0031] Beneficial effects of this invention:

[0032] This invention can effectively reduce the technical difficulties related to polymerization reactions in high-viscosity systems, improve polymerization efficiency, reduce the reaction risks of high-pressure, high-temperature, and high-viscosity systems, solve the technical problems of poor heat removal and easy temperature runaway in existing polymerization reactors in high-viscosity reaction systems, and reduce the fluctuation of reaction temperature and reaction pressure in solution polymerization reaction systems. Attached Figure Description

[0033] Figure 1 A schematic diagram of a high-pressure polymerization reactor with two heat medium outlets and one cold medium outlet;

[0034] Figure 2 This is a schematic diagram of a high-pressure polymerization reactor with three heat medium outlets and three cold medium outlets.

[0035] In the attached figures, the following labels are used:

[0036] 1. High-pressure nitrogen inlet;

[0037] 2. Catalyst inlet;

[0038] 3. Stirring shaft;

[0039] 4. Stirrer;

[0040] M1. Stirring motor;

[0041] N1. Raw material inlet;

[0042] N2. Discharge port;

[0043] L1. Lamp hole;

[0044] T1, T2, T3. Temperature detection ports;

[0045] J1. High-voltage sight glass;

[0046] F1. High-pressure sealed shut-off valve;

[0047] F2. High-pressure sealed ball valve;

[0048] L1. Insulation layer;

[0049] P1. Cooling coil;

[0050] P2. Heating coil;

[0051] S1. Heat medium import;

[0052] S2, S3, S4. Heat medium outlet;

[0053] C1. Refrigerant inlet;

[0054] C2, C3, C4. Refrigerant outlet Detailed Implementation

[0055] The present invention will now be described in detail through embodiments. It should be noted that the following embodiments are only for further illustration of the present invention and should not be construed as limiting the scope of protection of the present invention. Those skilled in the art can make some non-essential improvements and adjustments to the present invention based on the above description.

[0056] Please refer to Figure 1 and Figure 2 This invention provides an apparatus for olefin solution polymerization, the apparatus being a high-pressure polymerization reactor. The high-pressure polymerization reactor includes a shell, within which a stirring shaft 3 is installed. The upper end of the stirring shaft 3 extends out of the shell and is connected to a stirring motor M1, while the lower end of the stirring shaft 3 is connected to a stirrer 4. The shell includes an outer shell and an inner liner. A heating coil P2 and a cooling coil P1 are provided inside the inner liner. The heating coil P2 and the cooling coil P1 are arranged in a counter-rotating double helix structure, spirally wound around the inner liner from top to bottom. Both the heating coil P2 and the cooling coil P1 are cantilevered floating coils. The heating coil P2 includes a heat medium inlet S1 located at the top and two heat medium outlets S2 and S3. One heat medium outlet S2 is located at the bottom of the heating coil P2, and the other heat medium outlet S3 is located in the middle of the heating coil P2. Figure 2 As shown, the heating coil P2 may also include another heat medium outlet S4 in the middle; the cooling coil P1 includes a refrigerant inlet C1 located at the bottom, and at least two other refrigerant outlets C2 and C3, wherein one refrigerant outlet C2 is located at the top of the cooling coil P1, and the other refrigerant outlet C3 is located in the middle of the cooling coil P1, as shown. Figure 2 As shown, the middle part of the refrigerant coil P1 may also include another refrigerant outlet C4.

[0057] As a specific embodiment, the inner diameter of the heating coil P2 is 10-20mm, and the distance between two adjacent heating coils P2 is 20-30mm.

[0058] As a specific embodiment, the inner diameter of the cooling coil P1 is 10-15mm, and the distance between two adjacent cooling coils P1 is 10-20mm.

[0059] As a specific embodiment, the distance between adjacent cooling coil P1 and heating coil P2 is 3-5 mm.

[0060] As a specific embodiment, the top of the housing is provided with a high-pressure nitrogen inlet 1, a catalyst inlet 2, a raw material inlet N1, a lamp hole L1, a high-pressure sight glass J1, a temperature detection port T3, and a high-pressure sealing shut-off valve F1.

[0061] As a specific embodiment, the bottom of the housing is provided with temperature detection ports T2 and T3, a high-pressure sealing ball valve F2, and a discharge port N2.

[0062] As a specific embodiment, the high-pressure polymerization reactor is an open reactor, including a reactor body, an upper head and a lower head, wherein the reactor body and the upper and lower heads are connected by a quick-opening ring flange.

[0063] As a specific embodiment, the outer side of the shell is provided with a heat insulation layer L1.

[0064] As a specific embodiment, the heating coil P2 or cooling coil P1 located at the bottom is 120-150mm from the bottom of the vessel.

[0065] As a specific embodiment, the temperature detection port is equipped with an internal thermocouple.

[0066] Source of raw materials or equipment: including raw material name, specifications, manufacturer, etc.

[0067]

[0068] Evaluation and analysis methods:

[0069] Polymerization activity was calculated using the following method:

[0070]

[0071] Polymerization activity unit: gCat·h

[0072] The detailed description and technical content of the present invention are explained below with reference to the accompanying drawings: The present invention will be further described below with reference to the accompanying drawings and embodiments. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention, and should not be used to limit the scope of protection of the present invention.

[0073] A method of using an olefin solution polymerization apparatus includes the following steps:

[0074] Step S1: The experiment is a full-bottle operation. Before the reaction, high-pressure nitrogen gas is introduced into the reactor through high-pressure nitrogen inlet 1 and the pressure is maintained at 2-6 MPa (the spare port can be connected to a ball valve for venting and balancing pressure).

[0075] Step S2: After the pressure inside the vessel stabilizes, heating steam is introduced through the heat medium inlet S1 into the heating coil (P2) to heat the vessel lining, and the temperature inside the vessel is slowly and continuously increased.

[0076] Step S3: Open the raw material inlet N1 and pass the pre-dissolved ethylene and α-olefin blend into the reactor liner.

[0077] Step S4: Turn on the stirring motor M1 to drive the stirring shaft 3 to stir. The stirring speed is 100-2500 r / min (adjust the speed according to the viscosity difference of the system).

[0078] Step S5: When the temperature rises to 50-100℃, open catalyst inlet 2 and pump the catalyst in through the catalyst feed pump. The feeding method is continuous feeding, and the catalyst input rate is 1-10 ml / min. Then the polymerization reaction begins.

[0079] Step S6: Since the reaction system is exothermic, in order to control the reaction temperature to be stable, the condensate is introduced into the cooling coil P1 from the cooling coil C1 and flows out from the refrigerant outlet C2. The condensate circulates in the coil. At the same time, the heating steam flow is reduced by the external intelligent flow meter to control the temperature of the reaction system to be stable until the required reaction temperature for the experiment is reached.

[0080] Step S7: Open the raw material inlet N1 and add the pre-dissolved comonomer during the reaction to supplement the raw material. The feed rate is 50ml / min to 300ml / min.

[0081] Step S8: After the catalyst is consumed, close the catalyst inlet 2.

[0082] Step S9: Close the raw material inlet N1 and stop feeding.

[0083] Step S10: Close the heat medium inlet S1 and stop the supply of heating steam.

[0084] Step S11: Increase the flow rate of condensate to slowly cool the entire system until the temperature drops to 20-50°C.

[0085] Step S12: Discharge the remaining material and blended solution through the bottom outlet N2 of the reactor, and observe whether the material in the reactor has been completely discharged through the high-pressure sight glass J1.

[0086] Example 1: High-pressure nitrogen gas was introduced into the reactor through high-pressure nitrogen inlet 1 until the gauge pressure reached 0.5 MPa. The vent was then opened to release the gas. This purging process was repeated three times, with the final venting cycle bringing the gauge pressure to 0 MPa. 1 L of a pre-dissolved ethylene-butene blend with a molar ratio of 1:1 was introduced into the reaction apparatus through feed inlet N1. High-pressure nitrogen gas was then introduced again until the gauge pressure reached 3.5 MPa.

[0087] Once the pressure inside the reactor stabilizes, set the steam flow rate to 80% in the control platform program, activate the heating structure, open the heat medium inlet S1, and heat the reaction device to 80°C via the heating coil P2. Start the stirring, setting the stirring speed to 400 r / min, and continue heating the reaction device to 90°C. Once the reactor temperature reaches 90°C, use 0.2 L of dispersant cyclohexane to flush 10 ml of co-catalyst MAO and 2 mg of metallocene catalyst into the reactor through catalyst inlet 2. The feeding method is continuous, with a feed rate of 5 ml. At the same time, increase the stirring speed to 500 r / min, and introduce ethylene gas through the high-pressure nitrogen inlet N1 based on the pressure inside the reactor, maintaining the pressure inside the reactor between 4.0-4.5. After the reaction stabilizes and the temperature rises to 120℃, set the condensate flow rate to 30% in the control platform program, open the refrigerant inlet C1 to introduce condensate, and set the steam flow rate to 10%. If the temperature fluctuates, the steam and condensate flow rates can be adjusted in real time to maintain the reaction temperature inside the reactor between 120℃ and 130℃, and the polymerization reaction begins.

[0088] Under this reaction pressure, the reaction continues until the catalyst is completely consumed. Then, the catalyst inlet 2 and the raw material inlet N1 are closed. On the control platform, the steam flow rate is set to 0%, the heat medium inlet S1 is closed, and heating is stopped. At the same time, the condensate flow rate is increased to 70% to cool the reaction device. When the temperature drops to 80-90°C, the condensate flow rate is increased to 90% until the temperature inside the reactor reaches 20-30°C. The condensate flow rate is then set to 0%, the condensate inlet valve is closed, the vent is opened to release the gas in the device, and the discharge port is opened to release the reaction products.

[0089] Example 2: The metallocene catalyst was evaluated using the same method as in Example 1, except that the raw material was changed to a blend of ethylene and octene with a molar ratio of ethylene:octene = 1 / 1.5.

[0090] Example 3: The metallocene catalyst was evaluated using the same method as in Example 1, except that the polymerization temperature was increased to between 140 and 150 °C.

[0091] Of course, the present invention may have other various embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications according to the present invention, but these corresponding changes and modifications should all fall within the protection scope of the claims of the present invention.

Claims

1. A process for the solution polymerization of olefins characterized in that, The device used is a high-pressure polymerization kettle, which comprises a shell, a stirring shaft arranged in the shell, an upper end of the stirring shaft extending out of the shell and connected with a stirring motor, and a stirrer connected with a lower end of the stirring shaft; the shell comprises an outer shell and an inner liner, a heating coil and a cooling coil are arranged on the inner liner, the heating coil and the cooling coil are double-helical structures and are helically wound from top to bottom around the inner liner, the heating coil and the cooling coil are cantilever floating coils, the heating coil comprises a heat medium inlet at the upper portion and a heat medium outlet at the lower portion, and the cooling coil comprises a cooling medium inlet at the lower portion and a cooling medium outlet at the upper portion; The heat medium outlet is at least two, one is located at the lower portion of the heating coil, and the other heat medium outlets are located at the middle portion of the heating coil; The cooling medium outlet is at least two, one is located at the upper portion of the cooling coil, and the other cooling medium outlets are located at the middle portion of the cooling coil; The inner diameter of the heating coil is 10-20 mm, and the spacing between adjacent two turns of the heating coil is 20-30 mm; The inner diameter of the cooling coil is 10-15 mm, and the spacing between adjacent two turns of the cooling coil is 10-20 mm; The method for polymerization comprises the following steps: nitrogen is introduced into the high-pressure reaction kettle, then the heat medium is introduced into the high-pressure reaction kettle through the heat medium inlet of the heating coil to heat the high-pressure reaction kettle, then the reaction raw material and the catalyst are introduced, and the cooling medium is introduced into the cooling medium inlet of the cooling coil, the cooling medium flows from bottom to top to remove heat from the reaction material, the amount of the heat medium and the cooling medium introduced is adjusted to maintain the stability of the reaction system temperature during the reaction, after the reaction is completed, the introduction of the heat medium is stopped and the flow of the cooling medium is increased, and the reaction system is discharged after cooling; The specific steps are as follows: Step S1: The experiment is full-kettle operation, before the reaction, high-pressure nitrogen is introduced into the reaction kettle through the high-pressure nitrogen inlet, and the pressure is maintained at 2-6 MPa; Step S2: After the pressure in the kettle is stabilized, heating steam is introduced into the heating coil through the heat medium inlet to heat the inner liner of the kettle, and the temperature in the kettle is slowly and continuously increased; Step S3: Open the raw material inlet, and introduce the pre-solved ethylene and α-olefin blend into the inner liner of the reaction kettle; Step S4: Start the stirring motor to drive the stirring shaft to stir, and the stirring speed is 100-2500 r / min; Step S5: After the temperature is increased to 50-100℃, open the catalyst inlet, and introduce the catalyst through the catalyst feeding pump, the feeding mode is continuous feeding, the catalyst feeding amount is 1-10 ml / min, and the polymerization reaction is started; Step S6: Since the reaction system generates heat, in order to control the stability of the reaction temperature, the condensate is introduced into the cooling coil from the cooling coil, and flows out from the cooling medium outlet, the condensate circulates in the coil, and at the same time, the heating steam flow is reduced by the intelligent flow meter outside the kettle to control the stability of the reaction system temperature, and the required reaction temperature is reached; Step S7: Open the raw material inlet, and supplement the pre-solved comonomer during the reaction, and the feeding amount is 50-300 ml / min; Step S8: After the catalyst is consumed, close the catalyst inlet; Step S9: Close the raw material inlet and stop feeding. Step S10: close the heat medium inlet, stop the heating steam; Step S11: increase the condensate flux, slowly cool the whole system, and reduce the temperature to 20-50℃; Step S12: discharge the remaining material and the blended solution through the bottom outlet, and observe the material in the kettle through the high-pressure sight glass.

2. The process for the solution polymerization of olefins according to claim 1, characterized in that, The distance between the adjacent cooling coil and the heating coil is 3-5mm.

3. The process for the solution polymerization of olefins according to claim 1, characterized in that, The top of the shell is provided with a high-pressure nitrogen inlet, a catalyst inlet, a raw material inlet, a lamp hole, a high-pressure sight glass, a temperature detection port, and a high-pressure sealing stop valve.

4. The process for the solution polymerization of olefins according to claim 1, characterized in that, The bottom of the shell is provided with a temperature detection port, a high-pressure sealing ball valve, and a discharge port.

5. The process for the solution polymerization of olefins according to claim 1, characterized in that, The high-pressure polymerization kettle is an open kettle, which comprises a kettle body, an upper head, and a lower head.

6. The process for the solution polymerization of olefins according to claim 1, characterized in that, The shell is provided with an insulating layer on the outside.

7. The process for the solution polymerization of olefins according to claim 1, characterized in that, The heating coil or the cooling coil located at the lowermost part is 120-150mm away from the kettle bottom.

8. The process for the solution polymerization of olefins according to claim 3, characterized in that, The temperature detection port is provided with a kettle thermocouple.

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