A 1-octene production plant and process with extended production cycle

Abstract

The application discloses a 1-octene production device and process with prolonged production cycle, which comprises a stirring reaction kettle for generating 1-octene through ethylene oligomerization under catalyst conditions; a solid-liquid centrifugal separation device for separating reaction materials into solid-phase oligomer flocculation and liquid-phase reaction materials under temperature and pressure conditions in which reaction activity is inhibited; a circulating pump and a heat exchanger, wherein the liquid-phase reaction materials separated by the centrifugal separation device are introduced into the heat exchanger through the circulating pump for heat removal, the circulating pump is designed with high flow rate and low lift, and the inner surfaces of the equipment and pipelines in contact with the materials in the material circulation loop are all subjected to polishing treatment, with a surface smoothness lower than 0.2 um. The application can effectively avoid the generation of oligomers on the kettle wall, the heat exchanger wall or the blockage of pipelines through the rapid separation of oligomer flocculation by the solid-liquid centrifugal separation device, the high flow rate and low lift design of the circulating pump and the polishing treatment of the material contact surface, thereby effectively guaranteeing the long-period operation of the reaction system.

Description

Technical Field

[0001] This invention relates to equipment and processes for the production of 1-octene, and more specifically, to a 1-octene production apparatus and process that can extend the production cycle. Background Technology

[0002] 1-Octene is an important basic chemical raw material used to prepare various fine chemical products, such as polyethylene, polypropylene, and alcohols. One of the main sources of 1-octene is ethylene oligomerization, which is also one of the main determinants of its production cost. With the increase in global ethylene production capacity, the supply of 1-octene will gradually increase. With the development of the global economy and the prosperity of the chemical industry, the demand for these products will continue to increase. Especially in emerging market countries such as China and India, due to their large populations and rapid industrialization, the demand for these chemical products will be even higher, and the 1-octene market is expected to show a steady growth trend in the coming years. Overall, the 1-octene market outlook is promising. Driven by the increase in global ethylene production capacity and the increasing demand for fine chemical products, the 1-octene market will show a steady growth trend.

[0003] Ethylene oligomerization is one of the main methods for producing high-purity linear α-olefins. Selective ethylene oligomerization, in particular, is characterized by high catalytic activity, high selectivity for the target product, and good economic efficiency, making it the primary method for producing high-purity linear α-olefins. Domestically, 1-octene is largely dependent on imports, and there are currently no mature industrial-scale 1-octene production facilities. The main bottleneck is the generation of oligomers and other byproducts during the synthesis process, which adhere to the catalyst system needed to obtain highly selective 1-octene. These oligomers adhere to the reaction system, causing blockages, low 1-octene content, and low operating rates. Existing industrial-scale 1-octene facilities generally cannot achieve long-term stable and economical operation; production systems require shutdown to clean up blockages caused by oligomers after less than 24 hours of operation.

[0004] The development of the widely used selective oligomerization (SOL) technology for ethylene faces two main challenges. First, it requires improving the catalytic activity of the catalytic system and the selectivity of the target product to reduce production costs. More importantly, it demands the scale-up of the SOL technology for industrial application, achieving economical, stable, and long-term operation of the plant. This is a prerequisite for the large-scale industrial application of this technology. Many researchers and engineers have conducted extensive research and development work on how to achieve long-term, economical, and stable operation of the plant through industrial means, but an ideal solution has yet to be found.

[0005] Furthermore, the selective oligomerization of ethylene is characterized by low reaction temperature and high exothermic activity. Using a reactor jacket and internal coils presents challenges such as low heat removal efficiency, and the tendency for oligomer wax to adhere to the reactor walls, heat exchanger walls, and pipelines, making long-term continuous operation difficult. Moreover, due to the complexity of process control during the reaction, achieving a consistently high yield of 1-octene is challenging. Therefore, given the characteristics and existing problems of the 1-octene reaction system, there is an urgent need in this field to find an effective technical solution to ensure the long-term, economical, and stable operation of 1-octene production facilities. This solution has significant industrial value and a pressing market demand. Summary of the Invention

[0006] To address the aforementioned problems in the prior art, this invention provides a 1-octene production apparatus and process that can extend the production cycle, enabling continuous industrial production of 1-octene.

[0007] According to a first aspect of the present invention, the present invention provides a 1-octene production apparatus with an extended production cycle, comprising:

[0008] A stirred reactor is used to produce 1-octene via ethylene oligomerization under catalytic conditions.

[0009] The solid-liquid centrifugal separation equipment is set in the material circulation loop, downstream of the reactor outlet. The reactants are separated into solid oligomeric flocs and liquid reactants under temperature and pressure conditions that inhibit the reaction activity.

[0010] The circulating pump and heat exchanger are used to deheat the liquid-phase reaction material separated by the centrifugal separation equipment. The flow rate of the circulating pump is set to allow the material in the circulation loop to circulate once within 15s-45s.

[0011] All equipment and pipelines that come into contact with materials in the material circulation loop are polished, with a surface finish of less than 0.2 μm.

[0012] In some embodiments of the present invention, the operating temperature of the solid-liquid centrifugal separation device is 1℃-2℃.

[0013] In some embodiments of the present invention, the production apparatus further includes a flocculent separation system, wherein the solid-phase oligomeric flocculents separated by the solid-liquid centrifugal separation equipment are separated from the solvent by the flocculent separation system, and the solvent and flocculents are recovered.

[0014] In some embodiments of the present invention, the production apparatus further includes a termination system connected via pipeline to a solid-liquid centrifugal separation device and a flocculent separation system, and configured as follows:

[0015] When the temperature and / or pressure inside the solid-liquid centrifugal separator exceeds a predetermined value, the system terminates by adding a quencher to the centrifugal separator to control the temperature and / or pressure inside the solid-liquid centrifugal separator, thereby inhibiting the reactivity of the reactants.

[0016] When the oligomeric flocs entering the floc separation system are reactive, the system terminates by adding a quencher to the floc separation system to inhibit the reactivity of the oligomeric flocs.

[0017] In some embodiments of the present invention, the throat diameter of the circulating pump is > DN40.

[0018] In some embodiments of the present invention, the flocculent separation system is provided with a steam inlet and a solvent evaporation outlet, and the solvent is recovered by evaporation.

[0019] In some embodiments of the present invention, the heat exchanger is a fixed tube sheet heat exchanger and is installed longitudinally.

[0020] In some embodiments of the present invention, the termination system employs a 1.8 MPa-2.0 MPa CO gas-phase quencher.

[0021] According to a second aspect of the present invention, the present invention provides a 1-octene production process with an extended production cycle, comprising the following steps:

[0022] The reactants from the reactor are separated into solid oligomeric flocs and liquid reactants by solid-liquid centrifugation. The centrifugation is carried out under temperature and pressure conditions that inhibit the reactivity of the reaction.

[0023] All equipment and pipelines in the material circulation loop that come into contact with the material are polished, with a surface finish of less than 0.2 μm.

[0024] The liquid-phase reactants separated by centrifugation enter the heat exchanger for heat removal via a circulating pump along the material circulation loop. The flow rate of the circulating pump is set such that the material in the circulation loop circulates once within 15s-45s, ensuring that the residence time of the material in the circulation loop is sufficient to meet the heat removal requirements, but without causing adhesion to the inner surfaces of equipment and pipelines in contact with the material in the circulation loop.

[0025] In some embodiments of the present invention, the production process further includes:

[0026] When the operating temperature and / or pressure of solid-liquid centrifugation exceeds the predetermined value, a quencher is added to the centrifugation equipment to control the temperature and / or pressure inside the solid-liquid centrifugation equipment, thereby inhibiting the reactivity of the reactants.

[0027] When the oligomeric flocs entering the floc separation system are reactive, a quencher is added to the floc separation system to inhibit the reactivity of the oligomeric flocs.

[0028] In some embodiments of the present invention, the operating temperature for the solid-liquid centrifugal separation is 1°C-2°C.

[0029] In some embodiments of the present invention, the production process further includes: performing floc separation on the solid oligomeric flocs separated by centrifugation, wherein the floc separation includes evaporating and recovering the solvent by steam heating; and adding a quencher to the reaction material when the temperature and / or pressure of the centrifuged reaction material exceeds a predetermined value.

[0030] In some embodiments of the present invention, the production process further includes: when the reactants contain active oligomeric flocculents, a termination treatment is performed during centrifugation to quench the reaction activity and then evaporate the solvent for recovery; the termination treatment can be performed by CO gas-phase quenching at 1.8-2.0 MPa.

[0031] The present invention has the following advantages over the prior art:

[0032] (1) The 1-octene production device of the present invention adds a low temperature high flow rate solid-liquid centrifugal separation device, which effectively separates the oligomers in the reaction material from the material circulation pipeline. At the same time, the centrifugal separation operation adopts a low temperature control that is much lower than the reaction process temperature, which effectively inhibits the reaction activity, so that the reaction activity of the material in the centrifugal separation device is extremely weakened, which can avoid the risk of system blockage caused by explosive agglomeration in a small space.

[0033] (2) In the 1-octene production device of the present invention, a high-flow-rate, low-head circulating pump is adopted (the flow rate achieves a 15s-45s circulation cycle of the reaction system material based on the design of a low-head pump outlet throat diameter DN>40), and the pipelines in the circulation loop and the material contact surfaces inside the equipment are polished (the surface finish reaches below 0.2μm). This provides power for the high-speed circulation of materials during the reaction process. It can not only match the system material residence time and improve the heat removal efficiency, but also enable the generated oligomers to be quickly separated by solid-liquid centrifugal separation equipment without adhesion. The flocculent matter generated during the reaction process is efficiently and timely separated out of the system. Therefore, it can effectively avoid the generation of oligomers hanging on the reactor wall, heat exchanger wall or blocking pipelines, thereby effectively ensuring the long-term operation of the reaction system.

[0034] (3) The present invention can effectively achieve high yield of 1-octene by controlling the temperature and pressure process range with a narrow distribution, and at the same time by controlling the low temperature and high pressure process; and can effectively achieve the activation termination and recovery of flocculents by CO termination. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of a 1-octene production apparatus according to a specific embodiment of the present invention. Detailed Implementation

[0036] The various aspects of the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. Those skilled in the art should understand that the various embodiments described below are for illustrative purposes only and are not intended to limit the scope of protection of the present invention.

[0037] The following provides a detailed description of the 1-octene production apparatus and production process used in specific embodiments of the present invention.

[0038] like Figure 1 As shown, the 1-octene production apparatus of a specific embodiment of the present invention includes: a stirred reactor 1, a solid-liquid centrifugal separation device 2, a circulating pump 3, a heat exchanger 4, a flocculent separation system 5, a termination system 6, and a flocculent recovery system 7.

[0039] In this embodiment, the reactor 1 used for the preparation of 1-octene by ethylene oligomerization has an effective volume of 1m³. 3 The stirred reactor is 82% filled. The surfaces in contact with the material inside the reactor are mirror-polished, with a surface finish of 0.08μm. The reactor has three layers of agitators, with the lowest agitator point 25mm from the bottom of the reactor. Three layers of distributors, each with eight nozzles, are installed when the liquid level is below 75%. The gap between the feed pipe inlet and the agitator is 8mm. All feed and discharge ports inside the reactor are equipped with solvent flushing lines and plunger valves.

[0040] In this embodiment, the specific steps for preparing 1-octene by ethylene oligomerization using this reactor are as follows:

[0041] The reactor was purged with nitrogen, with oxygen and water content both at 1 ppm. After passing the purging, ethylene was used to purge the nitrogen from the reactor. The reactor's pressure was then 20 kPa and temperature was 6°C. Toluene solvent and triethylaluminum co-catalyst were added to the reactor. The solvent flow rate was controlled at 204 parts / h, and the co-catalyst flow rate at 0.5 parts / h. Once the liquid level reached 3%, the agitator, centrifuge, and external circulation pump were started. At this point, the external circulation pump outlet valve was opened at 5%-15%. One part of hydrogen regulator was added to the reactor at once. Then, 408 parts of ethylene were introduced into the reactor. When the ethylene flow rate is 300 parts by volume / hour, the pressure in the reactor gradually increases, and the temperature rises slightly. When the pressure reaches 5.8 MPa, the ethylene feed circuit regulating valve automatically opens and is cascaded with the reactor pressure. The set value is set to 6.00 MPa, and it automatically follows the changes in reactor pressure to adjust the ethylene feed rate, thereby ensuring that the reactor pressure is stable at 6.1 MPa. When the ethylene feed rate reaches 136 parts by volume, the ethylene feed flow rate automatically decreases to 181 parts by volume / hour, thereby effectively controlling the pressure inside the reactor at the beginning and end of the reaction to be stable at 6.05-6.15 MPa.

[0042] When the pressure inside the reactor reaches 6.0 MPa, a chromium-based main catalyst is added dropwise at a flow rate of 2.5 L / h, initiating the ethylene oligomerization reaction. When the reactor temperature reaches 17°C, the main catalyst flow rate automatically decreases to 58%-64% of the initial flow rate. After the ethylene feed reaches 136 parts by volume of the total ethylene, the ethylene flow rate decreases to 181 parts by volume / hour. When the reactor temperature is ≤14°C, the external circulating chilled water valve is automatically closed. The reactor pressure is controlled by the ethylene feed flow rate. When the reactor temperature reaches 16°C, the external circulating chilled water valve automatically opens. The material circulation temperature setpoint of heat exchanger 4 automatically follows the reactor temperature change and is controlled by the external circulating chilled water valve, thereby effectively controlling the reactor temperature to remain stable at 17.5-18.5°C during the reaction process.

[0043] When the reactor reaches a certain liquid level, under the same conditions, the liquid level difference per unit time in the reactor decreases significantly, indicating that the reaction activity has decreased. The reactor is then unloaded to the next stage to terminate the process and obtain reaction material containing 1-octene, solvent, and oligomeric flocculants.

[0044] The reactants enter the solid-liquid centrifugal separator 2 from the reactor outlet along the material circulation pipeline, and the chilled water cooling pipeline is put into operation to control the temperature of the centrifugal separator 2 at a low temperature of 1℃-2℃. In this embodiment, the temperature of the centrifugal separator 2 is controlled at 1.2℃ to inhibit the reactivity of the materials and avoid polymerization reactions that could cause blockages in the confined space of the centrifugal separator. To effectively control the temperature of the centrifugal separation operation, the production device in this embodiment also includes a termination system 6. When the temperature and / or pressure of the centrifugal separator 2 rises, the termination system 6 adds quencher to the solid-liquid centrifugal separator 2 through the quencher inlet provided with the solid-liquid centrifugal separator 2 to control the rise in temperature and / or pressure and inhibit the reactivity of the reactants. The amount of quencher added can be determined as needed, and automatic quantitative feeding and instantaneous quenching can be achieved. In this embodiment, a 1.8-2.0 MPa CO gas phase quencher is used.

[0045] The 1-octene production apparatus of this embodiment also includes a flocculent separation system 5, which comprises a 1m 3 In the atmospheric pressure tank with a stirrer, when the solid-liquid centrifugal separator 2 is started, the flocculent separation system is also started simultaneously. The flocculent separation system is equipped with a steam inlet and a steam outlet. The solid-phase oligomeric flocculents separated in real time by the solid-liquid centrifugal separator 2 are received by opening the inlet valve. When the oligomeric flocculents entering the flocculent separation system are reactive, the system 6 is terminated and a quencher is added to the flocculent separation system 5 to quench the reactivity of the oligomeric flocculents. In this example, CO quencher is used. When the liquid level of the flocculent separation system reaches 30% and the reactivity is quenched, 1.2 MPa steam is introduced into the flocculent separation vessel, and the temperature is controlled at 117.5℃. The bottom scraper agitator is started for stirring, and the steam outlet valve is opened to continuously recover the solvent in the material through steam. When the solvent content is less than 0.1%, the steam outlet valve is closed, and the solvent-free flocculents are introduced into the demineralized water inlet to cool to 40℃-45℃, and then discharged to the flocculent recovery system 7 for centralized collection.

[0046] The liquid phase reactant separated by the solid-liquid centrifugal separator 2 enters the circulating pump 3 and heat exchanger 4 sequentially along the circulation pipeline. The circulating pump 3 is set with a high flow rate and low head. The flow rate and head settings of the circulating pump not only need to match the system material residence time to meet the heat removal efficiency requirements, but also enable the oligomer flocs to be quickly separated by the solid-liquid centrifugal separator, avoiding the oligomers from adhering to the reactor wall, heat exchanger wall, or clogging the pipeline. In this embodiment, the circulating pump flow rate is 120 m / s. 3 / h, head is 25m, pump outlet throat diameter is DN50.

[0047] In this embodiment, heat exchanger 4 is a fixed tube sheet heat exchanger, installed vertically, with a heat exchange area of ​​120㎡; the total length of the circulation pipeline is 20m, and the material circulation cycle is 15s-25s.

[0048] The flocculent recovery system 7 in this embodiment includes a set of ton bag receiving devices with holes on both sides. The upper end of the ton bag is suspended and covers the discharge pipeline of the flocculent separation system 5, and the lower end is placed on a plastic base connected to a water tank. The water-laden flocculents generated by the flocculent separation system 5 enter the ton bag of the flocculent recovery system 7, the water is automatically separated and collected in the water tank, and the naturally dried flocculents are uniformly recovered.

[0049] In addition, the surfaces inside the circulation pipeline that come into contact with the material in this embodiment have all been mirror-polished, and their surface finish is controlled at 0.18 μm. In other words, the surfaces inside the equipment in the circulation loop, such as the reactor 1, the solid-liquid centrifugal separation device 2, the circulation pump 3, and the heat exchanger 4, that come into contact with the material have all been mirror-polished.

[0050] According to the 1-octene production apparatus and method of the present invention, oligomeric flocculants in the reactants can be separated in real time, effectively avoiding equipment and pipeline blockage problems, and enabling long-term operation for more than six months; at the same time, due to the high flow rate system, heat exchange efficiency is improved, process control is more stable, and the conversion rate of 1-octene can be effectively improved while reducing operating costs, with catalyst selectivity reaching as high as 5.2*10. 6 g(product) / g(catalyst).

[0051] To further demonstrate the technical effects of the present invention, three comparative examples are provided below for comparison.

[0052] 1. Comparative Example 1

[0053] The difference between Comparative Example 1 and the 1-octene production apparatus used in the embodiments of the present invention is that it does not include a solid-liquid centrifuge, a flocculant separation system, or a recovery system; all other settings are the same as in the embodiments of the present invention. Experiments revealed that in Comparative Example 1, the oligomeric flocculants produced by the reaction accumulate and adhere within the system. Even though all surfaces in contact with the materials in the production apparatus were polished, their surface finish was consistent with that in the embodiments of the present invention. The prolonged accumulation of flocculants in Comparative Example 1 led to the adhesion and blockage of the reactants, severely affecting catalyst activity. The apparatus operating cycle was less than one week, and the catalyst activity was 4.8*10⁻⁶. 4 Therefore, compared to Comparative Example 1, the operating cycle of the production apparatus in this embodiment of the invention is significantly extended, and the catalyst activity is increased by two orders of magnitude.

[0054] 2. Comparative Example 2

[0055] The difference between Comparative Example 2 and the 1-octene production apparatus used in the embodiments of the present invention is that the surfaces in contact with the materials in the production apparatus were not polished, and their surface finish was 1.0 μm. All other settings were the same as in the embodiments of the present invention. Experiments revealed that in Comparative Example 2, the flocculent material produced by the reaction rapidly adhered within the system. Even with a solid-liquid centrifugal separation device and a flocculent separation system, the flocculent material could not be effectively separated, severely affecting catalyst activity. The apparatus operating cycle was less than two weeks, and the catalyst activity was 2.8 × 10⁻⁶. 4 Therefore, compared to Comparative Example 2, the operating cycle of the production apparatus in this embodiment of the invention is significantly extended, and the catalyst activity is increased by two orders of magnitude.

[0056] 3. Comparative Example 3

[0057] The difference between Comparative Example 3 and the 1-octene production apparatus used in the embodiments of the present invention is that the circulating pump in the production apparatus is replaced with one with a flow rate of 20 m / s. 3 The pump head is 100m, the outlet throat size is DN15, and other settings are the same as in the embodiment of the present invention. Experiments revealed that in Comparative Example 3, the flocculent material generated by the reaction accumulates and adheres within the system. Even with a solid-liquid centrifugal separation device and a flocculent separation system, and polishing of the material contact surfaces inside the device, the flocculent material remains in the system for a long time and still adheres. Simultaneously, the increased head of the circulating pump inevitably reduces the outlet throat size, causing most of the flocculent material to accumulate at the throat outlet and become increasingly clogged, leading to the entire device becoming inoperable. This also severely affects catalyst activity, reducing the operating cycle to less than 12 hours, and the catalyst activity to 2.1*10⁻⁶. 4 g(product) / g(catalyst). Therefore, compared to Comparative Example 3, the operating cycle of the production apparatus in this embodiment of the invention is significantly extended, and the catalyst activity is increased by two orders of magnitude.

[0058] The comparison shows that the present invention, by setting a solid-liquid centrifugal separation device in the 1-octene production unit, separates solid-phase oligomeric flocs from the reactants under low-temperature conditions. At the same time, by setting the high flow rate and low head of the circulating pump, and polishing the material contact surfaces inside the device, the centrifuged liquid-phase reactants in the circulation loop can not only match the system material residence time to meet the heat removal efficiency requirements, but also enable the oligomeric flocs to be quickly separated by the solid-liquid centrifugal separation device, avoiding the oligomers from adhering to the reactor wall, heat exchanger wall, or clogging the pipeline, thereby avoiding the blockage of the circulation pipeline and extending the production cycle.

[0059] It should be noted that the specific embodiments described above are merely illustrative examples and do not constitute any limitation on the scope of protection of this application. Without departing from the basic concept of this invention, those skilled in the art can make various modifications and substitutions to the details involved in the above embodiments, and all such modifications and substitutions will fall within the scope of protection of this invention.

Claims

1. A 1-octene production apparatus capable of extending a production cycle, characterized by, The device comprises: a stirred reactor for producing 1-octene by ethylene oligomerization under catalyst conditions; a solid-liquid centrifugal separation device arranged in a material circulation loop downstream of the reactor outlet, through which the reaction material is separated into solid-phase oligomer flocculate and liquid-phase reaction material under temperature and pressure conditions in which the reaction activity is inhibited; a circulating pump and a heat exchanger, through which the liquid-phase reaction material separated by the centrifugal separation device is pumped into the heat exchanger for heat removal, the flow rate of the circulating pump being set so that the material in the circulation loop circulates once in 15-45 s; the inner surfaces of the equipment and pipelines in contact with the material in the material circulation loop are polished to a surface finish of less than 0.2 um.

2. The production apparatus according to claim 1, wherein The operating temperature of the solid-liquid centrifugal separation device is 1-2°C.

3. The production apparatus according to claim 1, wherein The device further comprises: a flocculate separation system through which the solid-phase oligomer flocculate separated by the solid-liquid centrifugal separation device is separated from the solvent, and the solvent and flocculate are recovered.

4. The production apparatus according to claim 3, wherein The device further comprises a termination system connected to the solid-liquid centrifugal separation device and the flocculate separation system through pipelines and arranged to: when the temperature and / or pressure in the solid-liquid centrifugal separation device exceeds a predetermined value, the termination system adds a quenching agent to the solid-liquid centrifugal separation device to control the temperature and / or pressure in the solid-liquid centrifugal separation device, thereby inhibiting the reaction activity of the reaction material; when the oligomer flocculate entering the flocculate separation system has reaction activity, the termination system adds a quenching agent to the flocculate separation system to inhibit the reaction activity of the oligomer flocculate.

5. The production device according to claim 1, wherein: the throat diameter of the circulating pump is greater than DN40.

6. The production apparatus according to claim 3, wherein The flocculate separation system is provided with a steam inlet and a solvent vapor outlet, and the solvent is recovered by evaporation.

7. The production apparatus according to claim 1, wherein The heat exchanger is a fixed tube sheet heat exchanger installed in the longitudinal direction.

8. The production apparatus according to claim 4, wherein The termination system uses a 1.8-2.0 MPa CO gas-phase quenching agent.

9. A process for the production of 1-octene with an extendable production cycle, characterized in that, The production process comprises the following steps: the reaction material from the reactor is separated into solid-phase oligomer flocculate and liquid-phase reaction material by solid-liquid centrifugal separation, and the centrifugal separation is performed under temperature and / or pressure conditions in which the reaction activity is inhibited; the inner surfaces of the equipment and pipelines in contact with the material in the material circulation loop are polished to a surface finish of less than 0.2 um; the liquid-phase reaction material separated by centrifugation is pumped into the heat exchanger along the material circulation loop by a circulating pump for heat removal, and the flow rate of the circulating pump is set so that the material in the circulation loop circulates once in 15-45 s, so that the residence time of the material in the circulation loop is sufficient to meet the heat removal requirement, but the material does not adhere to the inner surfaces of the equipment and pipelines in contact with the material in the circulation loop.

10. The production process according to claim 9, characterized in that, The production process further comprises: when the operating temperature and / or pressure of the solid-liquid centrifugal separation exceeds a predetermined value, a quenching agent is added to the solid-liquid centrifugal separation device to control the temperature and / or pressure in the solid-liquid centrifugal separation device, thereby inhibiting the reaction activity of the reaction material; when the oligomer flocculate entering the flocculate separation system has reaction activity, a quenching agent is added to the flocculate separation system to inhibit the reaction activity of the oligomer flocculate.

11. The production process according to claim 9, wherein The operating temperature of the solid-liquid centrifugal separation is 1-2℃.

12. The production process according to claim 9, wherein The production process further comprises: The centrifugally separated solid phase oligomeric flocculate is subjected to flocculate separation, which comprises evaporative recovery of the solvent using steam heating.

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