A process and apparatus for the production of polyolefins

Abstract

The application discloses a polyolefin production method and device, and belongs to the field of olefin polymerization. The method comprises the following steps: taking mother liquor containing low-molecular-weight polymer as a polymerization solvent of a first reactor, then introducing slurry products of the first reactor into a second reactor, and finally performing washing, filtering, drying, granulating and other processes on slurry products discharged from the second reactor, and / or performing washing on the slurry products of the first reactor, and then performing filtering, drying, granulating and other processes on the slurry products of the first reactor together with the slurry products discharged from the second reactor, so that high-performance polyolefin products with ultra-wide molecular weight distribution are obtained, the processing performance and use performance of the polyolefin can be simultaneously improved, and the method has the advantages of simple process flow, large operation flexibility and the like.

Description

Technical Field

[0001] This invention belongs to the field of olefin polymerization, and specifically relates to a method and apparatus for producing polyolefins. Background Technology

[0002] Polyethylene is a thermoplastic resin widely used in agriculture, petrochemicals, construction, and municipal engineering due to its excellent chemical stability, resistance to chemical corrosion, good processing performance, and superior electrical insulation. Polyethylene production processes include slurry processing, gas-phase processing, and solution processing. Compared to other processes, the slurry processing technology was developed earlier and boasts superior overall performance. The slurry polyethylene process primarily uses two or three reactors connected in series to produce high-density polyethylene grades, such as pipes, fibers, and hollow products. With increasingly stringent environmental regulations and a broader market demand for polyolefin products, competition in the polyolefin industry is intensifying, leading to faster technological upgrades and product replacements. High-performance polyolefin grades have become a key research focus for the slurry polyethylene process.

[0003] The rapid development of gas-phase processes and catalysts in recent years has posed a strong challenge to existing slurry process equipment. Therefore, improving the performance of polyethylene produced by slurry process equipment and expanding the production range of the equipment are key focuses for industrial plants. In summary, this invention aims to develop a new slurry process for producing polyolefins, achieving the production of high-performance, high-value-added polyethylene products. Summary of the Invention

[0004] This invention addresses the shortcomings of existing technologies by providing a method and apparatus for producing polyolefins.

[0005] In a first aspect, the present invention provides a method for producing polyolefins: an oligomer is prepared into a mother liquor by mixing an oligomer with a solvent, wherein the oligomer has a molecular weight of 150-10000 g / mol, a molecular weight distribution range of 2-50, and a branching degree of 0.5-100C / 10000C; the mother liquor is introduced into a first reactor, where reactive monomers and a catalyst are introduced to the first reactor to produce a polymerization reaction and generate a first slurry containing a first polymer powder; the first slurry in the first reactor is introduced into a second reactor, where reactive monomers and a catalyst are simultaneously introduced to the second reactor to produce a second slurry containing a second polymer powder; the second slurry in the second reactor is introduced into a scrubber, where a solvent is introduced to the scrubber to dissolve the free low molecular weight polymers on the surface of the second polymer powder and / or the low molecular weight polymers suspended in the second slurry, resulting in a third slurry; the third slurry in the scrubber is introduced into a liquid-solid separator for liquid-solid separation; the liquid separated by the liquid-solid separator is refined by a solvent to obtain a solvent and a low molecular weight polymer; the solid separated by the liquid-solid separator is dried and sent to a granulation system to obtain a high-performance polyolefin product.

[0006] Secondly, the present invention provides another method for producing polyolefins: an oligomer is prepared by mixing an oligomer with a solvent to form a mother liquor, wherein the oligomer has a molecular weight of 150-10000 g / mol, a molecular weight distribution range of 2-50, and a branching degree of 0.5-100C / 10000C; the mother liquor is introduced into a first reactor, and reactive monomers and a catalyst are introduced into the first reactor to undergo a polymerization reaction to generate a first slurry containing a first polymer powder; the first slurry in the first reactor is introduced into a scrubber, and simultaneously a solvent is introduced into the scrubber to remove the free low molecular weight polymers and / or loose polymers on the surface of the first polymer powder. Alternatively, the low molecular weight polymer suspended in the first slurry is dissolved to obtain a third slurry; the third slurry in the washer is introduced into a liquid-solid separator; a reactive monomer and a catalyst are introduced into a second reactor to produce a polymerization reaction and generate a second slurry containing a second polymer powder; the second slurry in the second reactor is introduced into the liquid-solid separator, which mixes the third slurry and the second slurry and performs liquid-solid separation on the mixed slurry; the separated liquid is refined by solvent to obtain solvent and low molecular weight polymer, and the solid separated by the liquid-solid separator is dried and sent to a granulation system to obtain a high-performance polyolefin product.

[0007] In some embodiments of the present invention, the molecular weight of the oligomers described in the two optional methods mentioned above is 150-10000 g / mol, and the molecular weight distribution range is 2-50, preferably 200-3000 g / mol, and the molecular weight distribution is 2-10.

[0008] In some embodiments of the present invention, the degree of branching of the oligomers described in the two aforementioned optional methods is 0.01-100C / 10000C, preferably 0.03-50C / 10000C.

[0009] In some embodiments of the present invention, the oligomer may be one or more of polyethylene wax, polypropylene wax, polyamide wax, Fischer-Tropsch wax, paraffin wax, oxidized polyethylene wax, and oxidized polypropylene wax.

[0010] It should be noted that, since oligomers may undergo slight changes in molecular weight, molecular weight distribution, or branching degree during the polymerization of polyolefins, the low molecular weight polymers in the above-described method of this invention refer to both oligomers that do not change during the reaction and those that undergo the aforementioned changes. These low molecular weight polymers may differ from the oligomers used to prepare the mother liquor. If the low molecular weight polymer obtained after solvent purification of the liquid (obtained from solid-liquid separation) in the aforementioned method meets the requirements of this invention for oligomers (molecular weight, molecular weight distribution, or branching degree), it can be reused for mother liquor preparation. However, if the low molecular weight polymer obtained does not meet the requirements of this invention, it cannot be directly reused.

[0011] In some embodiments of the present invention, the oligomers in the mother liquor of the two aforementioned optional methods are completely dissolved in the solvent.

[0012] In some embodiments of the present invention, the oligomers in the mother liquor of the two aforementioned optional methods are partially dissolved in the solvent.

[0013] In some embodiments of the present invention, the mass ratio of the oligomer introduced into the first reactor by the aforementioned two optional methods to the mass ratio of the first polymer powder is 1:100-1:1.

[0014] In some embodiments of the present invention, the reaction monomers in the two optional methods described above are one or more of C2 to C20 olefins, and the reaction monomers in the first reactor and the second reactor may be the same or different.

[0015] In some embodiments of the present invention, the catalyst described in the two aforementioned optional methods consists of a main catalyst and a co-catalyst, wherein the main catalyst is selected from one or more of Ziegler-Natta catalysts, metallocene catalysts, non-metallocene catalysts, chromium-based catalysts, post-transition metal catalysts, and pre-transition metal catalysts, and the co-catalyst is selected from one or more of alkylaluminum, alkylaluminoxanes, modified alkylaluminoxanes, and boranes.

[0016] In some embodiments of the present invention, the reaction temperature of the first reactor in the aforementioned two optional methods is -30 to 200°C, and the reaction pressure is 0.1 to 10 MPa.

[0017] In some embodiments of the present invention, the reaction temperature of the second reactor in the two aforementioned optional methods is 40-150°C, and the reaction pressure is 0.3-5 MPa.

[0018] In some embodiments of the present invention, the solvent in the two aforementioned alternative methods is a saturated hydrocarbon having 3 to 15 carbon atoms.

[0019] Thirdly, the present invention further provides an apparatus for implementing the aforementioned two alternative production methods, specifically comprising:

[0020] A mother liquor preparation tank for preparing mother liquor from oligomers and solvents, wherein the preparation tank is provided with an oligomer inlet, a solvent inlet and a mother liquor outlet;

[0021] A first reactor and a second reactor are used for olefin polymerization. The first reactor is provided with a catalyst inlet, a mother liquor inlet, a reactant monomer inlet, and a slurry outlet. The second reactor is provided with a catalyst inlet, a slurry inlet, a reactant monomer inlet, and a slurry outlet.

[0022] A scrubber for washing dissolved and free low molecular weight polymers, the scrubber having a slurry inlet, a solvent inlet, and a slurry outlet;

[0023] A liquid-solid separator for liquid-solid separation of slurry, the liquid-solid separator having a first slurry inlet, a second slurry inlet, a liquid outlet, and a solid outlet;

[0024] A dryer for drying polymer powders, the dryer having a solid inlet and a solid outlet;

[0025] A granulator for granulating polymer powders, the granulator being equipped with a solid feed inlet and a product outlet;

[0026] Solvent refining systems for solvent refining and separation;

[0027] The mother liquor outlet of the mother liquor preparation tank is connected to the mother liquor inlet of the first reactor;

[0028] The slurry outlet of the first reactor is connected to the slurry inlet of the second reactor and / or to the slurry inlet of the scrubber;

[0029] The slurry outlet of the second reactor is connected to the slurry inlet of the scrubber and / or to the first slurry inlet of the liquid-solid separator;

[0030] The slurry outlet of the scrubber is connected to the second slurry inlet of the liquid-solid separator;

[0031] The liquid outlet of the liquid-solid separator is connected to the solvent refining system, and the solid outlet of the liquid-solid separator is connected to the solid inlet of the dryer.

[0032] The solid outlet of the dryer is connected to the solid feed port of the granulator;

[0033] The solvent purification system is connected to the oligomer inlet and / or the solvent inlet of the scrubber.

[0034] In some embodiments of the present invention, the device operates continuously by controlling the valve.

[0035] In some embodiments of the present invention, the device operates intermittently by controlling the valve.

[0036] In some embodiments of the present invention, the first reactor is a batch reactor or a loop reactor.

[0037] In some embodiments of the present invention, the second reactor is a batch reactor or a loop reactor.

[0038] In some embodiments of the present invention, the combination of the first reactor and the second reactor is any combination of a batch reactor and a loop reactor.

[0039] In some embodiments of the present invention, the loading coefficient of the batch reactor is 0.4-1.

[0040] In some embodiments of the present invention, the liquid-solid separator is selected from a belt press filter, a plate and frame filter press, or a centrifuge.

[0041] This invention uses a mother liquor containing oligomers as the polymerization solvent in a first reactor, then introduces the slurry product from the first reactor into a second reactor. The slurry product discharged from the second reactor undergoes washing, filtration, drying, and granulation processes, and / or the slurry product from the first reactor is washed and then combined with the slurry product discharged from the second reactor for filtration, drying, and granulation processes to obtain a high-performance polyolefin product with an ultra-wide molecular weight distribution, thereby achieving a simultaneous improvement in the processing and performance of polyolefins. Attached Figure Description

[0042] Figure 1 This is a schematic diagram of a polyolefin production apparatus provided by the present invention.

[0043] Figure 2 This is a schematic diagram of another polyolefin production apparatus provided by the present invention.

[0044] Wherein: 1-Mother liquor preparation tank; 2-First reactor; 3-Second reactor; 4-Washer; 5-Liquid-solid separator; 6-Dryer; 7-Granulator. Detailed Implementation

[0045] The present invention will be further described below with reference to embodiments and accompanying drawings, but the scope of protection of the present invention is not limited thereto:

[0046] like Figures 1-2 As shown, the polyolefin production apparatus provided by the present invention includes: a mother liquor preparation tank 1 for preparing mother liquor from oligomers and solvents, the preparation tank having an oligomer inlet, a solvent inlet, and a mother liquor outlet; a first reactor 2 and a second reactor 3 for olefin polymerization, the first reactor having a catalyst inlet, a mother liquor inlet, a reactant monomer inlet, and a slurry outlet, and the second reactor having a catalyst inlet, a slurry inlet, a reactant monomer inlet, and a slurry outlet; a washer 4 for washing dissolved free low molecular weight polymers, the washer having a slurry inlet, a solvent inlet, and a slurry outlet; a liquid-solid separator 5 for liquid-solid separation of the slurry, the liquid-solid separator having a first slurry inlet, a second slurry inlet, a liquid outlet, and a solid outlet; a dryer 6 for drying polymer powder, the dryer having a solid inlet and a solid outlet; a granulator 7 for granulating polymer powder, the granulator having a solid feed port and a product outlet; a solvent refining system for solvent refining and separation; and the mother liquor preparation tank... The mother liquor outlet is connected to the mother liquor inlet of the first reactor; the slurry outlet of the first reactor is connected to the slurry inlet of the second reactor and / or to the slurry inlet of the scrubber; the slurry outlet of the second reactor is connected to the slurry inlet of the scrubber and / or to the first slurry inlet of the liquid-solid separator; the slurry outlet of the scrubber is connected to the second slurry inlet of the liquid-solid separator; the liquid outlet of the liquid-solid separator is connected to the solvent refining system; the solid outlet of the liquid-solid separator is connected to the solid inlet of the dryer; the solid outlet of the dryer is connected to the solid feed port of the granulator; a portion of the solvent and low molecular weight polymer separated by the solvent refining system (the separated low molecular weight polymer is required to meet the requirements of the present invention regarding oligomer molecular weight, molecular weight distribution, or branching degree) are respectively injected into the mother liquor preparation tank through the solvent inlet and oligomer inlet of the mother liquor preparation tank; a portion of the solvent separated by the solvent refining system is injected into the scrubber through the solvent inlet of the scrubber.

[0047] Figures 1-2 The diagrams show two polyolefin production methods based on the above-mentioned apparatus, which are formed by opening and closing valves on the pipeline. Both processes can be implemented based on the same set of production equipment and can produce high-performance polyolefins with ultra-wide molecular weight distribution.

[0048] Figures 1-2In the production method, the common parts are as follows: oligomers are added from the oligomer inlet of the mother liquor preparation tank, solvents are added from the solvent inlet of the mother liquor preparation tank, the mother liquor prepared in the mother liquor preparation tank is introduced into the first reactor, the slurry discharged from the slurry outlet of the scrubber is introduced into the liquid-solid separator through the second slurry inlet of the liquid-solid separator, the liquid discharged from the liquid outlet of the liquid-solid separator is introduced into the solvent refining system, a portion of the solvent and low molecular weight polymer (the low molecular weight polymer obtained by separation is required to meet the requirements of the present invention for oligomer molecular weight, molecular weight distribution or branching degree) separated from the solvent refining system are respectively introduced into the mother liquor preparation tank through the oligomer inlet and the solvent inlet of the mother liquor preparation tank, a portion of the solvent separated from the solvent refining system is introduced into the scrubber through the solvent inlet on the scrubber, the polymer discharged from the solid outlet of the liquid-solid separator is introduced into the dryer through the solid inlet of the dryer, the solid discharged from the solid outlet of the dryer enters the granulator through the solid feed port of the granulator, and the product is obtained at the product outlet of the granulator.

[0049] in, Figure 1 In the process, the slurry discharged from the outlet of the first reactor is introduced into the second reactor through the slurry inlet of the second reactor by means of valve control, and the slurry discharged from the outlet of the second reactor is introduced into the scrubber through the slurry inlet of the scrubber.

[0050] Figure 2 In the process, the slurry discharged from the outlet of the first reactor is introduced into the scrubber through the slurry inlet of the scrubber by the control of the valve, and the slurry discharged from the outlet of the second reactor is introduced into the liquid-solid separator through the first slurry inlet of the liquid-solid separator.

[0051] The oligomer has a molecular weight of 150-10000 g / mol, a molecular weight distribution range of 2-50, and a branching degree of 0.5-100C / 10000C.

[0052] Example 1

[0053] Adopting such Figure 1The apparatus shown is used for olefin polymerization with heptane as the solvent. Polyethylene wax with a molecular weight of 1200 g / mol, a molecular weight distribution range of 10, and a branching degree of 15C / 10000C is added to the mother liquor preparation tank. The polymer is completely dissolved in the solvent. The prepared mother liquor is introduced into the first reactor. Simultaneously, Zigler-Natta catalyst and triisobutylaluminum are added to both the first and second reactors. Ethylene is introduced from the bottom of the first reactor, while ethylene and 1-hexene are introduced from the bottom of the second reactor. The slurry discharged from the bottom of the first reactor is introduced into the second reactor. The slurry discharged from the second reactor undergoes washing, drying, and granulation processes to obtain the polymer product, the properties of which are shown in Table 1. The mass ratio of the oligomer introduced into the first reactor to the polymer powder generated in the first reactor is 1:10. The reaction temperature in the first reactor is 80℃ and the pressure is 0.4 MPa, while the reaction temperature in the second reactor is 85℃ and the pressure is 0.6 MPa. Both the first and second reactors are batch reactors with loading coefficients of 0.5 and 0.75, respectively. The liquid-solid separator is a centrifuge.

[0054] Example 2

[0055] Adopting such Figure 1 The apparatus shown was used for olefin polymerization under the same temperature, pressure, catalytic system and polymerization reactor type as in Example 1. The only difference from Example 1 was that hexane was used as the solvent. In this case, some undissolved oligomers (accounting for 20% of the total oligomer mass fraction) were suspended in the mother liquor. The properties of the polymer produced are shown in Table 1.

[0056] Comparative Example 1

[0057] Under the same temperature, pressure, catalytic system and polymerization reactor type as in Example 1, the only difference from Example 1 is that no oligomers are added to the mother liquor preparation tank, i.e. the mother liquor is a pure solvent. The properties of the obtained polymer are shown in Table 1.

[0058] Example 3

[0059] Adopting such Figure 2The apparatus shown performs olefin polymerization using heptane as a solvent. Polyethylene wax with a molecular weight of 5000 g / mol, a molecular weight distribution range of 30, and a branching degree of 40C / 10000C is added to the mother liquor preparation tank. At this point, some undissolved oligomers (accounting for 40% of the total oligomer mass fraction) are suspended in the mother liquor. The prepared mother liquor is introduced into the first reactor. Simultaneously, Zigler-Natta catalyst and methylaluminoxane are added to both the first and second reactors. Ethylene is introduced from the bottom of the first reactor, while ethylene and 1-butene are introduced from the bottom of the second reactor. The slurry discharged from the bottom of the first reactor is treated by a scrubber and then introduced into a liquid-solid separator. The slurry discharged from the second reactor is also introduced into the liquid-solid separator. The solids separated by the liquid-solid separator are dried and granulated to obtain the polymer product, the properties of which are shown in Table 1. The ratio of the mass of oligomer introduced into the first reactor to the mass of polymer powder generated in the first reactor is 1:3. The reaction temperature in the first reactor is 65℃ and the pressure is 3MPa. The reaction temperature in the second reactor is 75℃ and the pressure is 6MPa. The first reactor is a batch reactor with a loading coefficient of 0.6. The second reactor is a tubular reactor. The liquid-solid separator is a centrifuge.

[0060] Example 4

[0061] Under the same temperature, pressure, catalytic system, and polymerization reactor type as in Example 3, the only difference from Example 3 was the addition of polyethylene wax with a molecular weight of 2000 g / mol, a molecular weight distribution range of 20, and a branching degree of 18C / 10000C to the mother liquor. The properties of the resulting polymer are shown in Table 1.

[0062] Table 1 shows the performance test results of the polymer products in the examples.

[0063] Melt index (g / 10min) 2.6 2.3 0.5 1.8 2.0 Tensile strength (MPa) 97.9 88.6 29.1 64.5 72.7 Elongation at break (%) 31.2 23.9 82.9 35.6 30.4 Young's modulus (MPa) 720.4 615.7 432.8 550.3 654.6 <![CDATA[Impact strength (kJ / m 2 )]]> 82.3 70.6 11.4 53.8 68.4

[0064] The melt flow index test temperature was 190℃, and the load was 10kg.

[0065] As can be seen from the polymer performance test results in Table 1, the olefin polymers prepared by the apparatus and method provided by the present invention have both good flowability and excellent mechanical properties.

[0066] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention. The technical content for which protection is sought in the present invention has been fully described in the claims.

Claims

1. A method for producing polyolefins, characterized in that, An oligomer is prepared into a mother liquor by mixing an oligomer with a solvent. The oligomer is polyethylene wax with a molecular weight of 1200-5000 g / mol, a molecular weight distribution range of 10-30, and a branching degree of 15-40C / 10000C. The oligomer in the mother liquor is partially dissolved in the solvent. The mother liquor is introduced into a first reactor, and a reactive monomer and a catalyst are introduced into the first reactor to undergo a polymerization reaction to generate a first slurry containing a first polymer powder. The mass ratio of the oligomer introduced into the first reactor to the mass of the first polymer powder is 1:100-1:

1. The first slurry from the first reactor is introduced into the second reactor, where a monomer and a catalyst are simultaneously introduced to produce a second slurry containing a second polymer powder. The second slurry from the second reactor is then introduced into a scrubber, where a solvent is introduced to dissolve the free low-molecular-weight polymer on the surface of the second polymer powder and / or the low-molecular-weight polymer suspended in the second slurry, yielding a third slurry. The third slurry from the scrubber is then introduced into a liquid-solid separator for liquid-solid separation. The liquid separated by the liquid-solid separator is refined with a solvent to obtain the solvent and low-molecular-weight polymer. The solid separated by the liquid-solid separator is dried and sent to a granulation system to obtain a high-performance polyolefin product. The reaction temperature of the first reactor is -30 to 200°C, and the reaction pressure is 0.1 to 10 MPa. The reaction temperature of the second reactor is 40 to 150°C, and the reaction pressure is 0.3 to 5 MPa.

2. A method for producing polyolefins, characterized in that, An oligomer is prepared into a mother liquor by mixing an oligomer with a solvent. The oligomer is polyethylene wax with a molecular weight of 1200-5000 g / mol, a molecular weight distribution range of 10-30, and a branching degree of 15-40C / 10000C. The oligomer in the mother liquor is partially dissolved in the solvent. The mother liquor is introduced into a first reactor, and a reactive monomer and a catalyst are introduced into the first reactor to undergo a polymerization reaction to generate a first slurry containing a first polymer powder. The mass ratio of the oligomer introduced into the first reactor to the mass of the first polymer powder is 1:100-1:

1. The first slurry in the first reactor is introduced into a scrubber, and a solvent is introduced into the scrubber to dissolve the free low molecular weight polymer on the surface of the first polymer powder and / or the low molecular weight polymer suspended in the first slurry, to obtain a third slurry; the third slurry in the scrubber is introduced into a liquid-solid separator; reactive monomers and catalysts are introduced into a second reactor to undergo a polymerization reaction to generate a second slurry containing the second polymer powder, and the second slurry in the second reactor is introduced into the liquid-solid separator, where the third slurry and the second slurry are mixed and the mixed slurry is separated into liquid and solid; the separated liquid is refined by solvent to obtain solvent and low molecular weight polymer, and the solid separated by the liquid-solid separator is dried and sent to a granulation system to obtain a high-performance polyolefin product; the reaction temperature of the first reactor is -30-200℃, and the reaction pressure is 0.1-10 MPa; the reaction temperature of the second reactor is 40-150℃, and the reaction pressure is 0.3-5 MPa.

3. An apparatus for implementing the polyolefin production method according to claim 1 or 2, characterized in that, include: A mother liquor preparation tank (1) for preparing mother liquor from oligomers and solvents, wherein the preparation tank is provided with an oligomer inlet, a solvent inlet and a mother liquor outlet; A first reactor (2) and a second reactor (3) for olefin polymerization, wherein the first reactor is provided with a catalyst inlet, a mother liquor inlet, a reactant monomer inlet and a slurry outlet, and the second reactor is provided with a catalyst inlet, a slurry inlet and a reactant monomer inlet and a slurry outlet; A washer (4) for washing dissolved free low molecular weight polymers, the washer being provided with a slurry inlet, a solvent inlet, and a slurry outlet; A liquid-solid separator (5) for liquid-solid separation of slurry, wherein the liquid-solid separator is provided with a first slurry inlet, a second slurry inlet, a liquid outlet, and a solid outlet; A dryer (6) for drying polymer powder, the dryer having a solid inlet and a solid outlet; A granulator (7) for granulating polymer powder, wherein the granulator is provided with a solid feed port and a product outlet; Solvent refining systems for solvent refining and separation; The mother liquor outlet of the mother liquor preparation tank is connected to the mother liquor inlet of the first reactor; The slurry outlet of the first reactor is connected to the slurry inlet of the second reactor and / or to the slurry inlet of the scrubber; The slurry outlet of the second reactor is connected to the slurry inlet of the scrubber and / or to the first slurry inlet of the liquid-solid separator; The slurry outlet of the scrubber is connected to the second slurry inlet of the liquid-solid separator; The liquid outlet of the liquid-solid separator is connected to the solvent refining system, and the solid outlet of the liquid-solid separator is connected to the solid inlet of the dryer. The solid outlet of the dryer is connected to the solid feed port of the granulator; The solvent purification system is connected to the oligomer inlet and / or the solvent inlet of the scrubber.

4. The apparatus according to claim 3, characterized in that, Continuous and / or intermittent operation can be achieved through valve control.

5. The apparatus according to claim 3, characterized in that, The first reactor is a batch reactor or a loop reactor; and / or, the second reactor is a batch reactor or a loop reactor.

6. The apparatus according to claim 3, characterized in that, The liquid-solid separator is selected from belt press filter, plate and frame filter press or centrifuge.

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