System and method for continuous production of poly-alpha-olefins

Abstract

The application provides a system and method for continuously producing poly-alpha-olefins, the system comprising a polymerization reaction unit for polymerizing olefins; the polymerization reaction unit comprises at least two polymerization reactors arranged in series; and each polymerization reactor is independently provided with at least one set of heat exchange tube groups for regulating the reaction temperature in the polymerization reactor. By using the technical scheme of the application, the generation amount of dimers and the reaction temperature in the reaction process can be more effectively controlled. Thus, poly-alpha-olefin products with narrower molecular weight distribution and better performance can be obtained on the basis of high yield, and problems such as difficulty in effectively separating dimers in the reaction products, difficulty in controlling the temperature, and low product yield are effectively solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of poly-alpha-olefin preparation, in particular to a system and method for continuously producing poly-alpha-olefin. BACKGROUND

[0002] As a kind of excellent performance base oil, poly-alpha-olefin has the advantages of wide liquid phase range, low pour point, high viscosity index, good viscosity-temperature performance, high flash point, good low-temperature fluidity, good oxidation stability and thermal stability and small evaporation loss, and is widely used in harsh environments such as high-viscosity industrial gear oil, extreme cold hydraulic oil, screw compressor and refrigerator oil. At present, the average annual consumption growth rate of poly-alpha-olefin in China is about 5%. The proportion of high-quality lubricating oil demand in the overall demand for lubricating oil is increasing year by year, and the market demand for high-end lubricating oil products will drive the growth of poly-alpha-olefin demand.

[0003] At present, the medium and low-grade lubricating oils and most high-grade lubricating oils produced by cracking products of wax oil are being eliminated. The raw material base oil of domestic synthetic lubricating oil base oil depends on import, and the catalytic system is mostly AlCl3 as catalyst, which has the problem of large solid waste discharge.

[0004] Chinese invention patent CN104370675 mentions a method and device for preparing poly-alpha-olefin in a continuous manner, using a glassy micro-channel continuous reactor to carry out polymerization reaction in the presence of aluminum compound and co-catalyst to obtain poly-alpha-olefin. The catalyst consumption of this process technology is large, and the reaction needs a higher stable completion. US4045508 mentions a method for continuously preparing poly-alpha-olefin in purple red, which uses stirred tank and tubular reactor to control multi-step polymerization process. Chinese invention patent CN110627603A mentions a device and method for continuously producing poly-alpha-olefin, which adopts multiple reactors connected in series, the first stage is a stirred tank reactor and the second stage is a stirred tank reactor or a tubular reactor. This process is easy to form secondary polymerization reaction, and the content of trimer is greatly reduced. Chinese invention patent CN112299940A mentions a method and device for continuously preparing poly-alpha-olefin, which uses BF3 catalyst and co-catalyst to carry out polymerization reaction in multiple reactors connected in series and parallel. This process fails to separate the heavy components, which return to the reactor, resulting in increased production cost and incomplete separation of BF3 complex in the product. Chinese invention patent CN101054332B mentions a method for synthesizing poly-alpha-olefin oil, which uses BF3 and alcohol initiator in a process route of two-kettle parallel connection and evaporation-adsorption series connection. This process generates a large amount of solid waste. Chinese invention patent CN111939846A mentions a device and method for synthesizing poly-alpha-olefin, which has a constant reaction temperature device in the reactor, which can control the temperature of the reactor from being too high or too low. However, this device cannot well separate gas and liquid phases, and there are problems such as flow deviation.

[0005] In summary, the existing technology has complex process flow, large proportion of dimer in reaction product, poor product quality of polymerization product, incomplete catalyst separation, inability to precisely control reaction temperature, long process flow, inability to effectively separate catalyst and product, large amount of solid waste discharge, and other problems. Therefore, it is necessary to provide a new process for continuously producing poly-alpha-olefin to improve the above problems. SUMMARY

[0006] The main purpose of the present application is to provide a system and method for continuously producing poly-alpha-olefin, to solve the problems of large proportion of dimer in reaction product and difficulty in controlling temperature in the production of poly-alpha-olefin in the prior art.

[0007] In order to achieve the above-mentioned purpose, according to one aspect of the present application, a system for continuously producing poly-alpha-olefin is provided, which comprises a polymerization reaction unit for polymerizing olefins; the polymerization reaction unit comprises at least two polymerization reactors arranged in series; and at least one set of heat exchange pipe groups is independently arranged in each polymerization reactor for regulating the reaction temperature in the polymerization reactor.

[0008] Further, the system comprises a premixer, a first polymerization reactor, a second polymerization reactor, a first flash tank, a hydrogenation reactor and a rectifying column connected in sequence; the premixer has an olefin inlet and an additive inlet for premixing the olefin and the additive.

[0009] Further, the first polymerization reactor has a first feed inlet and a first catalyst inlet, the first feed inlet being connected to the outlet of the premixer; the first polymerization reactor further has a first gas phase outlet, a light component outlet and a first poly-alpha-olefin outlet.

[0010] Further, the second polymerization reactor has a second feed inlet and a second catalyst inlet, the second feed inlet being connected to the light component outlet of the first polymerization reactor; the second polymerization reactor further has a second gas phase outlet and a second poly-alpha-olefin outlet.

[0011] Further, the first polymerization reactor and the second polymerization reactor are each independently a bubble reactor or a stirred tank reactor.

[0012] Further, the first polymerization reactor is internally provided with at least one gas distributor connected to the first catalyst inlet through a communication channel for supplying the first catalyst to the interior of the first polymerization reactor; the second polymerization reactor is internally provided with at least one gas distributor connected to the second catalyst inlet through a communication channel for supplying the second catalyst to the interior of the second polymerization reactor; each gas distributor independently comprises a gas phase communication pipe and a plurality of jet nozzles, the gas phase communication pipe is provided with a plurality of gas outlets, the plurality of gas outlets and the plurality of jet nozzles are one-to-one correspondingly arranged, and the diameter of the jet nozzles is 1-5 mm.

[0013] Further, the inlet of the first flash tank is connected to the second poly-alpha-olefin outlet of the second polymerization reactor; the first flash tank further has a first liquid phase outlet and a third gas phase outlet; the first liquid phase outlet is connected to the hydrogenation reactor.

[0014] Further, the system further comprises a second flash tank; the inlet of the second flash tank is connected to the first gas phase outlet of the first polymerization reactor; the second flash tank further has a second liquid phase outlet and a fourth gas phase outlet; the second liquid phase outlet is connected to the second feed inlet of the second polymerization reactor.

[0015] Further, the system further comprises a liquid separation tank; the inlets of the liquid separation tank are respectively connected to the third gas phase outlet of the first flash tank and the fourth gas phase outlet of the second flash tank; the liquid separation tank further has a third liquid phase outlet and a fifth gas phase outlet; the third liquid phase outlet is connected to the second feed inlet of the second polymerization reactor.

[0016] Further, the system further comprises a compressor; an inlet of the compressor is connected with the fifth gas phase outlet of the liquid separator; an outlet of the compressor is connected with the first catalyst inlet of the first polymerization reactor and the second catalyst inlet of the second polymerization reactor respectively; preferably, the compressor is a diaphragm compressor, a piston compressor, a screw compressor or a centrifugal compressor.

[0017] In order to achieve the above-mentioned purpose, according to one aspect of the present application, a method for continuously producing poly-alpha-olefin by using the aforementioned system for continuously producing poly-alpha-olefin is provided, the method comprising the following steps: making the olefin pass through at least two polymerization reactors arranged in series to perform at least two polymerization reactions, so as to obtain poly-alpha-olefin.

[0018] Further, the method further comprises the following steps: making the auxiliary agent and the olefin pre-mix in a pre-mixer, then entering the first polymerization reactor to perform the first polymerization reaction under the action of the first catalyst, so as to obtain the first gas phase, light components and the first poly-alpha-olefin; making the light components enter the second polymerization reactor to perform the second polymerization reaction under the action of the second catalyst, so as to obtain the second gas phase and the second poly-alpha-olefin; making the first poly-alpha-olefin and the second poly-alpha-olefin enter the first flash tank to perform the first flash, so as to obtain the first liquid phase and the third gas phase; making the first liquid phase enter the hydrogenation reactor to perform the hydrogenation reaction, so as to obtain the hydrogenation product; making the hydrogenation product enter the rectifying column to perform the rectification, so as to obtain the poly-alpha-olefin with viscosity between 1.6 and 2.5, the poly-alpha-olefin with viscosity between 2.4 and 3.8 and the poly-alpha-olefin with viscosity between 7.8 and 8.5; preferably, the reaction temperature of the first polymerization reaction is 30-50℃; preferably, the reaction temperature of the second polymerization reaction is 60-80; preferably, the processing temperature of the first flash is 130-140℃; preferably, the processing temperature of the hydrogenation reaction is 240-260℃, the reaction pressure is 4-6 MPa, the hydrogen / oil ratio is 400-600:1, the volume space velocity is 0.5-1.5 h-1, and the hydrogenation product is the poly-alpha-olefin with viscosity between 1.6 and 2.5. -1 .

[0019] Further, the olefin is selected from one or more of C8-C12 olefins; preferably, the auxiliary agent is selected from one or more of isopropyl alcohol, ethanol, butanol, acetic acid or diethyl ether.

[0020] Further, the method further comprises the following steps: making the first gas phase and the second gas phase enter the second flash tank to perform the second flash, so as to obtain the second liquid phase and the fourth gas phase; making the fourth gas phase and the third gas phase enter the liquid separator to perform the liquid separation, so as to obtain the third liquid phase and the fifth gas phase; making the second liquid phase and the third liquid phase enter the second polymerization reactor to participate in the second polymerization reaction; making the fifth gas phase, after being processed by the compressor, participate in the first polymerization reaction and the second polymerization reaction as a catalyst; preferably, the processing temperature of the second flash is 140-150℃.

[0021] Further, the feeding amount of the olefin is 10-100 mL / min; the feeding amount of the auxiliary agent is 0.01-1 mL / min.

[0022] Further, the first catalyst and the second catalyst are each independently selected from a gas catalyst, and the gas catalyst is BF3; further preferably, the feeding amount of the first catalyst in the first polymerization reactor is 0.001-0.1 mL / min; the feeding amount of the second catalyst in the second polymerization reactor is 0.0001-0.01 L / min.

[0023] By using the technical scheme of the present application, the generation amount of the dimer and the reaction temperature can be more effectively controlled during the reaction, so that the poly-alpha-olefin product with narrower molecular weight distribution and better performance can be obtained on the basis of high yield, and the problems of large proportion of the dimer in the reaction product, difficulty in effective separation, difficulty in temperature control, and low product yield are effectively solved. BRIEF DESCRIPTION OF DRAWINGS

[0024] The drawings accompanying the specification of the present application form a part thereof, serve to provide further understanding of the present application, and together with the specification explain the present application, and do not constitute an improper limitation on the present application. In the drawings:

[0025] Figure 1 A schematic diagram of a system for continuously producing poly-alpha-olefin in an embodiment of the present application is shown; and

[0026] Figure 2 A schematic diagram of the structure of a polymerization reactor provided in an embodiment of the present application is shown.

[0027] In the above drawings, the following reference signs are used:

[0028] 10, pre-mixer; 20, first polymerization reactor; 30, second polymerization reactor; 40, first flash tank; 50, hydrogenation reactor; 60, rectifying column; 70, second flash tank; 80, liquid separation tank;

[0029] 100, shell; 110, upper cavity; 120, lower cavity; 130, cylindrical body; 140, upper partition; 150, liquid-phase material inlet; 160, catalyst material 1 inlet; 170, catalyst material 2 inlet; 180, lower partition; 190, light component outlet; 200, first heat exchange system; 210, first heat exchange tube group; 300, second heat exchange system; 310, second heat exchange tube group; 400, cyclone separator; 410, main body; 420, downcomer; 500, liquid-phase distributor; 600, No. 1 gas-phase distributor; 700, No. 2 gas-phase distributor; 810, upper head; 811, gas-phase outlet; 820, lower head; 821, liquid outlet. DETAILED DESCRIPTION

[0030] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0031] As described in the background section, the prior art has problems of high proportion of dimers in the reaction product, difficult control of temperature, etc. in the production of poly-alpha-olefins. In order to solve this problem, the present application provides a system for continuously producing poly-alpha-olefins. As shown in Figure 1 the system includes a polymerization reaction unit for polymerizing olefins; the polymerization reaction unit includes at least two polymerization reactors arranged in series; and each polymerization reactor is independently provided with at least one set of heat exchange pipe groups for regulating the reaction temperature in the polymerization reactor.

[0032] Based on this, the present application can more effectively control the amount of dimers generated and the reaction temperature during the reaction process. Thus, poly-alpha-olefin products with narrower molecular weight distribution and better performance can be obtained on the basis of high yield, effectively solving the problems of high proportion of dimers in the reaction product, difficult effective separation, difficult control of temperature, low product yield, etc.

[0033] In order to further improve the conversion rate of the product, in a preferred embodiment, the system includes a premixer 10, a first polymerization reactor 20, a second polymerization reactor 30, a first flash tank 40, a hydrogenation reactor 50, and a rectifying column 60 connected in series. The premixer 10 has an olefin inlet and an additive inlet for premixing olefins and additives. The first polymerization reactor 20 has a first feed inlet and a first catalyst inlet, and the first feed inlet is connected to the outlet of the premixer 10. The first polymerization reactor 20 also has a first gas phase outlet, a light component outlet, and a first poly-alpha-olefin outlet. The second polymerization reactor 30 has a second feed inlet and a second catalyst inlet, and the second feed inlet is connected to the light component outlet of the first polymerization reactor 20. The second polymerization reactor 30 also has a second gas phase outlet and a second poly-alpha-olefin outlet. The inlet of the first flash tank 40 is connected to the second poly-alpha-olefin outlet of the second polymerization reactor 30. The first flash tank 40 also has a first liquid phase outlet and a third gas phase outlet, and the first liquid phase outlet is connected to the hydrogenation reactor 50.

[0034] The olefins and the additives are premixed in the premixer 10, and then enter the first polymerization reactor 20 to perform the first polymerization reaction under the action of the first catalyst, so as to obtain the first gas phase, light components (unreacted components and dimer components) and the first poly-alpha-olefins. The light components continue to enter the second polymerization reactor 30 to perform the second polymerization reaction under the action of the second catalyst, so as to obtain the second gas phase and the second poly-alpha-olefins. The first poly-alpha-olefins and the second poly-alpha-olefins enter the first flash tank 40 to perform the first flash, so as to obtain the first liquid phase and the third gas phase. The first liquid phase continues to enter the hydrogenation reactor 50 to perform the hydrogenation reaction, so as to obtain the hydrogenation product. The hydrogenation product is sent to the rectifying tower 60 to perform the rectification, so as to obtain three viscosity poly-alpha-olefins, i.e., the poly-alpha-olefins with viscosity between 1.6 and 2.5, the poly-alpha-olefins with viscosity between 2.4 and 3.8, and the poly-alpha-olefins with viscosity between 7.8 and 8.5. Based on this, the preparation of poly-alpha-olefins with different viscosities is realized efficiently.

[0035] In a preferred embodiment, the first polymerization reactor 20 is internally provided with at least one gas distributor connected with the first catalyst inlet through a communication channel for supplying the first catalyst to the interior of the first polymerization reactor 20; the second polymerization reactor 30 is internally provided with at least one gas distributor connected with the second catalyst inlet through a communication channel for supplying the second catalyst to the interior of the second polymerization reactor 30; each gas distributor independently comprises a gas phase communication pipe and a plurality of jet nozzles, the gas phase communication pipe is provided with a plurality of gas outlets, the plurality of gas outlets and the plurality of jet nozzles are one-to-one arranged, and the diameter of the jet nozzles is 1-5 mm. Based on this, the action of the catalyst can be more effectively exerted, so as to make the polymerization reaction more efficient.

[0036] Specifically, the first polymerization reactor 20 and the second polymerization reactor 30 are independently a bubble reactor or a stirred tank reactor. In a preferred embodiment, a reactor as shown in FIG. 2 can be used. Figure 2The illustrated polymerization reactor (kettle-type stirring reactor) is used as a first polymerization reactor and a second polymerization reactor. The polymerization reactor comprises: a shell 100 having an upper cavity 110 and a lower cavity 120 in communication with each other; a first heat exchange system 200, the first heat exchange system 200 comprising a first temperature adjusting device and a first heat exchange pipe group 210, the first heat exchange pipe group 210 being arranged in the upper cavity 110 to exchange heat with the fluid in the upper cavity 110, the first temperature adjusting device being used to control the coolant entering the first heat exchange pipe group 210; a second heat exchange system 300, the second heat exchange system 300 comprising a second temperature adjusting device and a second heat exchange pipe group 310, the second heat exchange pipe group 310 being arranged in the lower cavity 120 to exchange heat with the fluid in the lower cavity 120, the second temperature adjusting device being used to control the coolant entering the second heat exchange pipe group 310, the number of the second heat exchange pipe group 310 being greater than the number of the first heat exchange pipe group 210; and a cyclone separator 400 arranged above the first heat exchange pipe group 210, the cyclone separator 400 being used to separate the gaseous phase product generated after the reaction into gas and liquid.

[0037] The cyclone separator 400 is arranged above the first heat exchange pipe group 210, so that the gaseous phase product generated after the reaction can enter the cyclone separator 400, the cyclone separator 400 separates the gaseous phase product into gas and liquid, and then the separated product is transported to the subsequent process; and the first heat exchange system 200 is arranged in the upper cavity 110, and the second heat exchange system 300 is arranged in the lower cavity 120, the temperature of the upper cavity 110 can be controlled by the first temperature adjusting device and the first heat exchange pipe group 210, and the temperature of the lower cavity can be controlled by the second temperature adjusting device and the second heat exchange pipe group 310, so as to control the reaction temperature in the whole reactor, thereby improving the reaction effect of the material during the reaction.

[0038] Specifically, the first temperature adjusting device comprises a first adjusting valve, a first temperature sensor and a first control part, the first adjusting valve is arranged on the input pipeline of the first heat exchange pipe group 210, the first temperature sensor is used to detect the temperature of the upper cavity 110, the first adjusting valve and the first temperature sensor are electrically connected with the first control part, the first control part is used to receive the temperature detected by the first temperature sensor, and the first control part controls the opening and closing of the first adjusting valve. The temperature signal of the upper cavity 110 detected by the first temperature sensor is transmitted to the first control part, and then the first control part controls the opening and closing of the first adjusting valve according to the received temperature, so as to realize the accurate control of the temperature of the upper cavity 110 and improve the reaction effect in the upper cavity 110.

[0039] Specifically, the second temperature adjusting device comprises a second adjusting valve, a second temperature sensor and a second control unit, the second adjusting valve is arranged on the input pipeline of the second heat exchange pipe group 310, the second temperature sensor is used for detecting the temperature of the lower cavity 120, and the second adjusting valve and the second temperature sensor are electrically connected with the second control unit, the second control unit is used for receiving the temperature detected by the second temperature sensor, and the second control unit controls the opening and closing of the second adjusting valve. The temperature signal of the lower cavity 120 detected by the second temperature sensor is transmitted to the second control unit, and then the second control unit controls the opening and closing of the second adjusting valve according to the received temperature, so as to realize the accurate control of the temperature of the lower cavity 120 and improve the reaction effect in the lower cavity 120. Through the above setting mode, the accurate control of the temperature of the inner cavity of the whole shell 100 is realized, and the problems of deflection and stock flow in the inner cavity of the shell 100 are prevented, so that the reaction is more sufficient.

[0040] Further, the shell 100 comprises a cylindrical body 130 and an upper partition plate 140 connected to the top of the cylindrical body 130, and the cyclone separator 400 comprises a main body 410 and a downcomer 420 in communication with the bottom of the main body 410, the top of the main body 410 is provided with a gas outlet, the sidewall of the main body 410 is provided with a gas inlet, at least a part of the main body 410 passes through the upper partition plate 140, the gas outlet is in communication with the gas phase outlet 811 at the top of the polyalphaolefin reactor, the gas inlet is in communication with the upper cavity 110, and the outlet of the downcomer 420 is located in the lower cavity 120. By adopting the above setting mode, the gas phase product generated after the reaction in the cylindrical body 130 enters through the gas inlet of the main body 410, and then is separated, the separated gas phase product enters the gas phase outlet of the polyalphaolefin reactor through the gas outlet of the main body 410 to enter the subsequent process, and the separated liquid phase product enters the lower cavity 120 through the downcomer 420 to continue the reaction.

[0041] Further, the cyclone separator 400 is a plurality of cyclone separators 400, and the plurality of cyclone separators 400 are uniformly distributed on the upper partition plate 140 along the circumference of the cylindrical body 130. By arranging the cyclone separator 400 as a plurality of cyclone separators 400, the separation effect of the gas phase product generated after the reaction is further improved.

[0042] In the embodiment, the polymerization reactor further comprises a liquid phase distributor 500, a first gas phase distributor 600 and a second gas phase distributor 700, the first gas phase distributor 600 divides the inner cavity of the shell 100 into an upper cavity 110 and a lower cavity 120, the liquid phase distributor 500 and the second gas phase distributor 700 are both located in the lower cavity 120, the side wall of the shell 100 further comprises a liquid material inlet 150, a catalyst material inlet 160 and a catalyst material inlet 170, the liquid material inlet 150 is communicated with the liquid phase distributor 500, the catalyst material inlet 160 is communicated with the first gas phase distributor 600, and the catalyst material inlet 170 is communicated with the second gas phase distributor 700. By arranging the liquid phase distributor 500, the liquid phase material entering through the liquid material inlet 150 is more uniformly distributed, and the reaction is more complete; by arranging the first gas phase distributor 600 and the second gas phase distributor 700, the gas phase material entering through the catalyst material inlet 160 and the catalyst material inlet 170 is more uniformly distributed, and the reaction effect is further improved.

[0043] The liquid phase distributor 500 has a liquid phase communication pipe and a plurality of discharge holes arranged on the liquid phase communication pipe, and the diameter of the discharge hole is 2mm-100mm. By setting the diameter of the discharge hole to 2mm-100mm, the liquid phase material can meet the reaction requirements. Specifically, the pipe arrangement mode of the liquid phase communication pipe is a concentric circle or a fishbone-shaped arrangement structure.

[0044] The shell 100 comprises a cylindrical body 130 and a lower partition plate 180 connected to the bottom of the cylindrical body 130, the first gas phase distributor 600 comprises a gas phase communication pipe and a plurality of gas injection nozzles, the gas phase communication pipe is provided with a plurality of gas discharge holes, the plurality of gas discharge holes and the plurality of gas injection nozzles are one-to-one corresponding, the diameter of the gas injection nozzle is 1mm-5mm, the gas injection direction of the gas injection nozzle is towards the lower partition plate 180, the structure of the second gas phase distributor 700 is the same as that of the first gas phase distributor 600, and the distance between the gas injection nozzle of the second gas phase distributor 700 and the lower partition plate 180 is 2mm-100mm. By arranging a plurality of gas discharge holes, and one-to-one corresponding the plurality of gas discharge holes and the plurality of gas injection nozzles, and by arranging the gas injection direction of the gas injection nozzle towards the lower partition plate 180, the gas phase material sprayed by the gas injection nozzle of the second gas phase distributor 700 towards the lower partition plate 180 bounces after impacting the lower partition plate 180, and uniformly contacts and reacts with the liquid phase material from bottom to top in the lower cavity 120, at the same time, the gas phase material sprayed by the gas injection nozzle of the first gas phase distributor 600 towards the lower partition plate 180 can form a convection with the gas phase material sprayed by the gas injection nozzle of the second gas phase distributor 700, so that the gas phase material is more uniformly distributed, and the reaction is more complete. The gas phase communication pipe is a concentric circle arrangement structure.

[0045] Further, the polymerization reactor further comprises an upper head 810 and a lower head 820, the upper head 810 is connected to the top of the shell 100, the upper head 810 and the upper partition plate 140 form a separation cavity, the gas outlet is communicated with the separation cavity, and the upper head 810 is provided with a gas phase outlet 811; the lower head 820 is connected to the bottom of the shell 100, and the lower head 820 is provided with a liquid discharge port 821 for discharging the accumulated liquid in the shell 100. The upper head 810 is arranged to form a separation cavity with the upper partition plate 140, so that the gas phase product separated by the cyclone separator 400 can be discharged; the liquid discharge port 821 is arranged to prevent the lower partition plate 180 from leaking and causing the accumulation of liquid in the lower head 820 and corroding the polymerization reactor after the polymerization reactor works for a long time.

[0046] In the embodiment, the side wall of the shell 100 further comprises a light component outlet 190, the light component outlet 190 is communicated with the upper cavity 110, and the light component outlet 190 is used for discharging the light components (unreacted components and dimer components) generated after the reaction.

[0047] In order to further effectively utilize the first gas phase and the second gas phase, in a preferred embodiment, the system further comprises a second flash tank 70; the inlet of the second flash tank 70 is communicated with the first gas phase outlet of the first polymerization reactor 20; the second flash tank 70 is further provided with a second liquid phase outlet and a fourth gas phase outlet; the second liquid phase outlet is communicated with the second feeding port of the second polymerization reactor 30. The system further comprises a separation tank 80; the inlets of the separation tank 80 are respectively communicated with the third gas phase outlet of the first flash tank 40 and the fourth gas phase outlet of the second flash tank 70; the separation tank 80 is further provided with a third liquid phase outlet and a fifth gas phase outlet; the third liquid phase outlet is communicated with the second feeding port of the second polymerization reactor 30. The system further comprises a compressor 90; the inlet of the compressor 90 is communicated with the fifth gas phase outlet of the separation tank 80; the outlet of the compressor 90 is respectively communicated with the first catalyst inlet of the first polymerization reactor 20 and the second catalyst inlet of the second polymerization reactor 30. Based on this, the fifth gas phase can participate in the first polymerization reaction and the second polymerization reaction after being treated by the compressor 90; at the same time, the second liquid phase and the third liquid phase can enter the second polymerization reactor 30 to participate in the second polymerization reaction, so that the material utilization rate is higher.

[0048] The application further provides a method for continuously producing poly-alpha-olefins by using the system for continuously producing poly-alpha-olefins, and the method comprises the following steps: making the olefins pass through at least two polymerization reactors arranged in series to perform at least two polymerization reactions, so as to obtain poly-alpha-olefins.

[0049] Based on the foregoing reasons, the present application can more effectively control the amount of dimer generated in the reaction process and the reaction temperature. Thus, a poly-alpha-olefin product with narrower molecular weight distribution and better performance can be obtained on the basis of high yield, effectively solving the problems of large proportion of dimer in the reaction product, difficult effective separation, difficult temperature control, and low product yield.

[0050] In a preferred embodiment, the method comprises the following steps: the adjuvant and the olefin are premixed in the premixer 10, then enter the first polymerization reactor 20 to perform the first polymerization reaction under the action of the first catalyst, to obtain the first gas phase, light components and the first poly-alpha-olefin; the light components enter the second polymerization reactor 30 to perform the second polymerization reaction under the action of the second catalyst, to obtain the second gas phase and the second poly-alpha-olefin; the first poly-alpha-olefin and the second poly-alpha-olefin enter the first flash tank 40 to perform the first flash, to obtain the first liquid phase and the third gas phase; the first liquid phase enters the hydrogenation reactor 50 to perform the hydrogenation reaction, to obtain the hydrogenation product; the hydrogenation product enters the rectifying column 60 to perform the rectification, to obtain the poly-alpha-olefin with viscosity between 1.6 and 2.5, the poly-alpha-olefin with viscosity between 2.4 and 3.8, and the poly-alpha-olefin with viscosity between 7.8 and 8.5. Preferably, the olefin is selected from one or more of C8 olefin, C9 olefin, C10 olefin, C11 olefin or C12 olefin; preferably, the adjuvant is selected from one or more of isopropyl alcohol, ethanol, butanol, acetic acid or diethyl ether. Additionally, the above-mentioned olefin can be a liquid mixed olefin, and the above-mentioned light components are also a liquid mixture.

[0051] Preferably, the reaction temperature of the first polymerization reaction is 30-50°C, for example, it can be 30°C, 35°C, 40°C, 45°C or 50°C; the reaction temperature of the second polymerization reaction is 60-80°C, for example, it can be 60°C, 65°C, 70°C, 75°C or 80°C; the processing temperature of the first flash is 130-140°C; the processing temperature during the hydrogenation reaction is 240-260°C, the reaction pressure is 4-6 MPa, the hydrogen / oil ratio is 400-600:1, and the volume space velocity is 0.5-1.5 h -1 .

[0052] In a preferred embodiment, the method further comprises the following steps: the first gas phase and the second gas phase enter the second flash tank 70 to perform the second flash, to obtain the second liquid phase and the fourth gas phase; the fourth gas phase and the third gas phase enter the liquid separator 80 to perform the liquid separation, to obtain the third liquid phase and the fifth gas phase; the second liquid phase and the third liquid phase enter the second polymerization reactor 30 to participate in the second polymerization reaction; the fifth gas phase is processed by the compressor 90, and then participates in the first polymerization reaction and the second polymerization reaction as a catalyst. Preferably, the processing temperature of the second flash is 140-150°C.

[0053] In a preferred embodiment, the feeding amount of the olefin is 10-100 mL / min; the feeding amount of the auxiliary agent is 0.01-1 mL / min. The first catalyst and the second catalyst are each independently a gas catalyst, preferably the BF3 gas catalyst is selected from one or more of the group consisting of BF3 gas catalysts with purity of 99.7%, 99.9% or 99.99%; further preferably, in the first polymerization reactor 20, the feeding amount of the first catalyst is 0.001-0.1 mL / min; in the second polymerization reactor 30, the feeding amount of the second catalyst is 0.0001-0.01 mL / min.

[0054] The application will be further described in detail below in connection with specific embodiments, which should not be construed as limiting the scope of the application.

[0055] Example 1

[0056] The system shown in Figure 1 is used to continuously produce poly-α-olefins. The polymerization reactor shown in Figure 2 is used as the first polymerization reactor and the second polymerization reactor.

[0057] The diameter of the gas outlet of the second gas distributor 700 is 5 mm, the diameter of the gas nozzle of the second gas distributor 700 is 3 mm, the distance between the gas nozzle of the second gas distributor 700 and the lower baffle plate 18 is 10 mm; the diameter of the gas outlet of the first gas distributor 600 is 8 mm, the diameter of the gas nozzle of the first gas distributor 600 is 5 mm; the diameter of the liquid outlet of the liquid distributor 500 is 10 mm, the number of the first heat exchange tube group 210 is 6, and the number of the second heat exchange tube group 310 is 10.

[0058] The method for continuously producing poly-α-olefins using the above device comprises the following steps:

[0059] The olefin (coal-derived olefin, the components of which are shown in Table 1) is pre-mixed in the pre-mixer 10 and then enters the first polymerization reactor 20 to perform the first polymerization reaction (50°C, 1 h) under the action of the first catalyst, to obtain the first gas phase, the light component and the first poly-α-olefin;

[0060] The light component enters the second polymerization reactor 30 to perform the second polymerization reaction (70°C, 1 h) under the action of the second catalyst, to obtain the second gas phase and the second poly-α-olefin;

[0061] The first poly-α-olefin and the second poly-α-olefin enter the first flash tank 40 to perform the first flash (135°C, 1 h), to obtain the first liquid phase and the third gas phase;

[0062] The first liquid phase is introduced into a hydrogenation reactor 50 to perform a hydrogenation reaction (hydrogenation temperature: 240 to 260°C, reaction pressure: 4 to 6 MPa, hydrogen / oil ratio: 500:1, volume space velocity: 1 h -1 ), to obtain a hydrogenation product;

[0063] The hydrogenation product is introduced into a rectifying column 60 to perform rectification (atmospheric distillation);

[0064] The first gas phase and the second gas phase are introduced into a second flash tank 70 to perform a second flash (150°C, 1 h), to obtain a second liquid phase and a fourth gas phase;

[0065] The fourth gas phase and the third gas phase are introduced into a liquid separator 80 to perform liquid separation, to obtain a third liquid phase and a fifth gas phase;

[0066] The second liquid phase and the third liquid phase are introduced into a second polymerization reactor 30 to participate in a second polymerization reaction;

[0067] The fifth gas phase is processed by a screw compressor 90, and is used as a catalyst to participate in the first polymerization reaction and the second polymerization reaction.

[0068] The conversion rate of the olefins is 98%. The trimer and the tetramer account for 85 wt%.

[0069] Table 1

[0070] Component Content / wt% C9 21 C10 53 C11 20 Oxygenate 4.2

[0071] Example 2

[0072] The difference from Example 1 is that the reaction temperature of the first polymerization reaction is 30°C.

[0073] The conversion rate of the olefins is 97.5%. The trimer and the tetramer account for 83.2 wt%

[0074] Example 3

[0075] The difference from Example 1 is that the reaction temperature of the first polymerization reaction is 60°C.

[0076] The conversion rate of the olefins is 94.8%. The trimer and the tetramer account for 70.2 wt%.

[0077] Example 4

[0078] The difference from Example 1 is that the reaction temperature of the second polymerization reaction is 80°C.

[0079] The conversion rate of the olefins is 96.2%. The trimer and the tetramer account for 83.5 wt%.

[0080] Example 5

[0081] The difference from Example 1 is that the reaction temperature of the second polymerization is 90°C.

[0082] The conversion of the olefin is 95.2%. The trimer and tetramer account for 68.4wt%.

[0083] Comparative Example 1

[0084] The difference from Example 1 is that no heat exchange tube set is arranged in the two polymerization reactors.

[0085] The conversion of the olefin is 94.0%. The trimer and tetramer account for 63.7wt%.

[0086] Comparative Example 2

[0087] The difference from Example 1 is that the reaction system does not include the second polymerization reactor.

[0088] The conversion of the olefin is 91.8%. The trimer and tetramer account for 61.7wt%.

[0089] The above merely describes the preferred embodiments of the present application and is not used to limit the present application. Any modification, equivalent replacement, improvement, etc. within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A system for the continuous production of polyα-olefins, said system comprising a polymerization reaction unit for polymerizing the olefins; characterized in that, The polymerization reaction unit includes at least two polymerization reactors connected in series; and each polymerization reactor is independently equipped with at least one set of heat exchange tubes for regulating the reaction temperature within the polymerization reactor. The system includes a premixer (10), a first polymerization reactor (20), a second polymerization reactor (30), a first flash tank (40), a hydrogenation reactor (50), and a distillation column (60) connected in sequence. The premixer (10) has an olefin inlet and an additive inlet for premixing olefins and additives; The first polymerization reactor (20) has a first feed inlet and a first catalyst inlet, and the first feed inlet is connected to the outlet of the premixer (10); The first polymerization reactor (20) also has a first gas phase outlet, a light component outlet and a first polyα-olefin outlet; the second polymerization reactor (30) has a second feed inlet and a second catalyst inlet, the second feed inlet being connected to the light component outlet of the first polymerization reactor (20); The second polymerization reactor (30) also has a second gas phase outlet and a second poly-α-olefin outlet; The inlet of the first flash tank (40) is connected to the second poly-α-olefin outlet of the second polymerization reactor (30); The first flash tank (40) also has a first liquid phase outlet and a third gas phase outlet; the first liquid phase outlet is connected to the hydrogenation reactor (50); The system also includes a second flash tank (70); The inlet of the second flash tank (70) is connected to the first gas phase outlet of the first polymerization reactor (20); The second flash tank (70) also has a second liquid phase outlet and a fourth gas phase outlet; the second liquid phase outlet is connected to the second feed inlet of the second polymerization reactor (30).

2. The system for continuous production of polyα-olefins according to claim 1, characterized in that, The first polymerization reactor (20) and the second polymerization reactor (30) are each independently a bubble reactor or a stirred tank reactor.

3. The system for continuous production of polyα-olefins according to claim 1, characterized in that, The first polymerization reactor (20) is provided with at least one gas distributor, which is connected to the first catalyst inlet through a connecting channel, for supplying the first catalyst to the interior of the first polymerization reactor (20); The second polymerization reactor (30) is provided with at least one gas distributor, which is connected to the second catalyst inlet through a connecting channel for supplying the second catalyst to the interior of the second polymerization reactor (30); Each of the gas distributors independently includes a gas connecting pipe and multiple jet nozzles. The gas connecting pipe is provided with multiple air outlets, and the multiple air outlets and multiple jet nozzles are arranged in a one-to-one correspondence. The diameter of the jet nozzles is 1~5mm.

4. The system for continuous production of polyα-olefins according to claim 1, characterized in that, The system also includes a liquid separator (80); The inlet of the separator (80) is connected to the third gas phase outlet of the first flash tank (40) and the fourth gas phase outlet of the second flash tank (70), respectively. The separator (80) also has a third liquid phase outlet and a fifth gas phase outlet; the third liquid phase outlet is connected to the second feed inlet of the second polymerization reactor (30).

5. The system for continuous production of polyα-olefins according to claim 4, characterized in that, The system also includes a compressor (90); The inlet of the compressor (90) is connected to the fifth gas phase outlet of the separator (80); The outlet of the compressor (90) is connected to the first catalyst inlet of the first polymerization reactor (20) and the second catalyst inlet of the second polymerization reactor (30), respectively; The compressor (90) is a diaphragm compressor, piston compressor, screw compressor, or centrifugal compressor.

6. A method for continuously producing polyalphaolefins using the system for continuous production of polyalphaolefins according to any one of claims 1 to 5, characterized in that, The method includes the following steps: The olefin is passed through at least two polymerization reactors arranged in series to undergo at least two polymerization reactions to obtain the polyα-olefin.

7. The method according to claim 6, characterized in that, The method includes the following steps: After the additives and olefins are premixed in the premixer (10), they enter the first polymerization reactor (20) and undergo the first polymerization reaction under the action of the first catalyst to obtain the first gas phase, light components and the first polyα-olefin; The light component is introduced into the second polymerization reactor (30), and a second polymerization reaction is carried out under the action of the second catalyst to obtain a second gas phase and a second polyα-olefin. The first polyα-olefin and the second polyα-olefin are introduced into the first flash tank (40) for first flash evaporation to obtain a first liquid phase and a third gas phase; The first liquid phase is introduced into the hydrogenation reactor (50) to carry out the hydrogenation reaction and obtain the hydrogenation product; The hydrogenated product is fed into a distillation column (60) for distillation to obtain poly-α-olefins with a viscosity between 1.6 and 2.5, poly-α-olefins with a viscosity between 2.4 and 3.8, and poly-α-olefins with a viscosity between 7.8 and 8.

5.

8. The method according to claim 7, characterized in that, The reaction temperature of the first polymerization reaction is 30~50℃; The reaction temperature for the second polymerization reaction is 60-80°C; The first flash evaporation process is carried out at a temperature of 130~140℃; The hydrogenation reaction process is carried out at a temperature of 240-260℃, a reaction pressure of 4-6 MPa, a hydrogen-to-oil ratio of 400-600:1, and a volume hourly space velocity of 0.5-1.5 h⁻¹. -1 .

9. The method according to claim 7, characterized in that, The olefin is selected from one or more of C8-C12 olefins; The adjuvant is selected from one or more of isopropanol, ethanol, butanol, acetic acid, or diethyl ether.

10. The method according to claim 9, characterized in that, The method further includes the following steps: The first gas phase and the second gas phase are introduced into the second flash tank (70) for second flash evaporation to obtain the second liquid phase and the fourth gas phase; The fourth gas phase and the third gas phase are introduced into the separator (80) for separation to obtain the third liquid phase and the fifth gas phase; The second liquid phase and the third liquid phase are introduced into the second polymerization reactor (30) to participate in the second polymerization reaction; The fifth gas phase is processed by a compressor (90) and then used as a catalyst in the first polymerization reaction and the second polymerization reaction.

11. The method according to claim 10, characterized in that, The second flash evaporation process is carried out at a temperature of 140~150℃.

12. The method according to claim 7, characterized in that, The olefin feed rate is 10~100 mL / min; the auxiliary agent feed rate is 0.01~1 mL / min.

13. The method according to claim 7, characterized in that, The first catalyst and the second catalyst are each independently selected from gaseous catalysts, wherein the gaseous catalyst is BF3; In the first polymerization reactor (20), the gas flow rate of the first catalyst is 0.001~0.1 mL / min; in the second polymerization reactor (30), the gas flow rate of the second catalyst is 0.0001~0.01 L / min.

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