Kettle washing device for washing vertical melt polycondensation reactor

Abstract

The utility model provides a kettle washing device for washing a vertical melt polycondensation reactor, and belongs to the technical field of polymerization equipment. Comprising an ethylene glycol circulation system, a slurry separation system and an ethylene glycol reflux system. The device takes liquid ethylene glycol as a kettle washing liquid, is applied to the cleaning operation of the vertical melt polycondensation reactor, and is beneficial to deeply cleaning the reactor and internal elements, optimizing the state of the reactor and improving the quality of polycondensation products; impurities such as melt residues, coking materials and carbon black remaining on the reactor and internal elements can be efficiently cleaned at low temperature, and cyclic utilization and recovery of ethylene glycol kettle washing liquid are achieved.

Description

Technical Field

[0001] The present application relates to a kettle washing device for cleaning a vertical melt polycondensation reactor, belonging to the technical field of polymerization equipment. Background Art

[0002] Vertical melt polycondensation reactor is a new type of polycondensation reactor developed in recent years. This type of reactor relies on gravity to save energy and protect the environment. The melt has very high heat and mass transfer efficiency during the flow process, which meets the devolatilization behavior of small molecular by-products in the polycondensation process of high viscosity melt, and can achieve very high polycondensation efficiency, thereby shortening production time and reducing production costs. At present, it has been applied to the industrial production of many high molecular weight polyester and polyamide materials, such as polyethylene terephthalate (PET), polypropylene terephthalate (PBT), polybutylene terephthalate (PTT), polyethylene naphthalate (PEN), polycarbonate (PC) and polyamide 6 (PA6).

[0003] The melt polycondensation process requires a higher reaction temperature, usually 20~30℃ higher than the melting point of the material. Higher reaction temperatures will lead to a series of side reactions, such as thermal degradation reactions, branching reactions, cross-linking reactions, etc., producing impurities such as oligomers, gels, and cokes that affect product quality. To solve such problems, during the industrial use of vertical melt polycondensation reactors, the reactors are periodically cleaned to remove impurities adhering to the reactors and internal components. At present, when cleaning vertical melt polycondensation reactors of high-viscosity PET in industry, the ethylene glycol steam washing method is more commonly used. By injecting high-temperature ethylene glycol vapor into the vertical melt polycondensation reactor and maintaining a slightly positive pressure on the reactor, it is evenly dispersed in various parts of the reactor to achieve the cleaning of the entire reactor. However, the ethylene glycol steam washing method has a low washing intensity, and has a weak cleaning effect on gels or cokes that have long been attached to the reactor and internal components, so that the reactor after cleaning still cannot reach the ideal production state. Eventually, the kettle washing cycle becomes shorter and shorter, and the production status gradually deteriorates, which seriously affects the continuity of industrial production, resulting in increased production costs and reduced production efficiency. Summary of the invention

[0004] In view of this, the present application provides a kettle washing device for cleaning a vertical melt polycondensation reactor, which uses liquid ethylene glycol as the kettle washing liquid, can efficiently clean impurities such as melt residues, coke and carbon black remaining on the reactor and internal components at a relatively low temperature, and realize the recycling and recovery of the ethylene glycol kettle washing liquid.

[0005] Specifically, the present application is implemented through the following scheme:

[0006] A kettle washing device for cleaning a vertical melt polycondensation reactor is used in conjunction with the vertical melt polycondensation reactor. The vertical melt polycondensation reactor comprises a feed pipe, a vertical shell and a discharge pipe. The feed pipe is connected to the top of the vertical shell, and the discharge pipe is connected to the bottom of the vertical shell. The vertical melt polycondensation reactor also comprises a slurry separation system, an ethylene glycol circulation system and an ethylene glycol reflux system.

[0007] The circulation pipe inlet of the ethylene glycol circulation system is connected to the bottom of the vertical shell, and the outlet is connected to the feed pipe.

[0008] The slurry separation system comprises a separation pipe, the inlet of the separation pipe is connected to the discharge pipe, and the outlet of the separation pipe is connected to the circulation pipe.

[0009] The inlet and outlet of the reflux pipe of the ethylene glycol reflux system are respectively connected to different positions of the circulation pipe, and the outlet is close to one end of the feed pipe.

[0010] Further, as a preference:

[0011] A gear pump, a settling tank and a first centrifugal pump are sequentially arranged along the separation pipe, the gear pump is close to one end of the discharge pipe, and valves are arranged on the pipelines between the gear pump and the discharge pipe, and between the first centrifugal pump and the circulation pipe. More preferably, the settling tank is connected to a first insoluble material discharge pipe. The gear pump, the settling tank, the first centrifugal pump and the corresponding separation pipe (not limited to a single pipe or a multi-section pipe) constitute a slurry separation system, the gear pump is used to drive the flow of ethylene glycol and polyester material slurry, the settling tank is used to separate the ethylene glycol solution and the insoluble material in the slurry, the first centrifugal pump is used to drive the flow of the ethylene glycol solution, and the valve is used to control the flow state of the ethylene glycol solution to separate the discharge.

[0012] A second centrifugal pump and a filter are arranged in sequence along the circulation pipe, the centrifugal pump is close to the vertical shell, the filter is close to the feed pipe, and valves are arranged on the pipes between the centrifugal pump and the bottom of the vertical shell, the centrifugal pump and the filter, and the filter and the feed pipe. The second centrifugal pump, the filter and the corresponding circulation pipe (not limited to a single pipe or a multi-section pipe) constitute an ethylene glycol circulation system, the second centrifugal pump is used to drive the flow of ethylene glycol solution; the filter is used to remove insoluble substances in ethylene glycol; the valve is used to control the flow state of ethylene glycol liquid and circulate the ethylene glycol that can be directly used.

[0013] The outlet of the slurry separation system is connected to the pipeline of the ethylene glycol circulation system, that is, the ethylene glycol solution separated by the sedimentation tank can enter the ethylene glycol circulation system to continue the cleaning of the reactor, thereby improving the utilization efficiency of the ethylene glycol reactor washing liquid and reducing production costs.

[0014] A third centrifugal pump, a crude ethylene glycol tank, a condenser, a recycled ethylene glycol tank, and a fourth centrifugal pump are sequentially arranged along the reflux pipe, the inlet and outlet of the crude ethylene glycol tank are both located above the tank body; the inlet of the condenser is arranged above; the inlet of the recycled ethylene glycol tank is located above the tank body, and the outlet is located below the tank body; valves are arranged on the circulation pipe between the third centrifugal pump and the circulation pipe, the fourth centrifugal pump and the circulation pipe, and the two interfaces between the third centrifugal pump, the fourth centrifugal pump and the circulation pipe. More preferably, the crude ethylene glycol tank is connected to a second insoluble material discharge pipe. The third centrifugal pump, the crude ethylene glycol tank, the condenser, the recycled ethylene glycol tank, the fourth centrifugal pump and the corresponding reflux pipe (not limited to a single pipe or a multi-section pipe) constitute an ethylene glycol reflux system. The third and fourth centrifugal pumps are used to drive the flow of the ethylene glycol solution; the crude ethylene glycol tank is used to store the ethylene glycol solution containing oligomers and can evaporate the ethylene glycol by heating; the condenser is used to condense the ethylene glycol vapor and convert it into liquid ethylene glycol; the recycled ethylene glycol tank is used to store the ethylene glycol liquid after evaporation and reflux; the valve is used to control the flow state of the ethylene glycol liquid and perform reflux processing on the ethylene glycol that needs to be treated and reused.

[0015] The inlet and outlet of the ethylene glycol reflux system are both connected to the ethylene glycol circulation system, which can recycle and store the ethylene glycol washing kettle liquid. In addition to being used in the kettle washing operation, the condensed ethylene glycol solution can also be used in other production units, such as polymerization slurry tanks, esterification reactors and three-stage ejectors.

[0016] In the above scheme,

[0017] A melt distributor is arranged on the top of the vertical shell, and a discharge pipe is connected to the melt distributor. A film distributor and a falling film element are arranged below the melt distributor for guiding the flow of materials. A conical bottom shell is arranged at the bottom of the vertical shell, and a spiral ribbon agitator is distributed in the conical bottom shell for stirring the melt. The discharge pipe is connected to the bottom outlet of the conical bottom shell.

[0018] The vertical shell is connected with a vacuum gas pipeline for controlling the vacuum degree inside the reactor.

[0019] The new kettle washing method realized by the kettle washing device of the present application is conducive to deep cleaning of the reactor and internal components, optimizing the reactor state, and improving the quality of the polycondensation product; it can maximize the recovery efficiency of ethylene glycol, increase the service life of the reactor, shorten the kettle washing cycle, and reduce production costs, which is of great significance to the industrial production of high molecular weight polyester and polyamide materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0021] Figure 1 This is a schematic diagram of the coordination relationship between the present application and the reactor;

[0022] Figure 2 This is a schematic diagram of the structure of this application;

[0023] Figure 3 This is a schematic diagram of the usage status of this application.

[0024] Numbers in the figure: A. Slurry separation system; B. Ethylene glycol circulation system; C. Ethylene glycol reflux system; 1. Feed pipeline; 2. Melt distributor; 3. Valve; 301. Valve 1; 302. Valve 2; 303. Valve 3; 304. Valve 4; 305. Valve 5; 306. Valve 6; 307. Valve 7; 308. Valve 8; 309. Valve 9; 310. Valve 10; 311. Valve 11; 312. Valve 12; 313. Valve 13; 4. Vacuum gas pipeline; 5. Vertical Type shell; 6. Film distributor; 7. Falling film element; 8. Screw-belt agitator; 9. Conical bottom shell; 10. Discharge pipe; 11. Gear pump; 12. Sedimentation tank; 13. Insoluble material discharge pipe; 1301. First insoluble material discharge pipe; 1302. Second insoluble material discharge pipe; 14. Centrifugal pump; 1401. Centrifugal pump one; 1402. Centrifugal pump two; 1403. Centrifugal pump three; 1404. Centrifugal pump four; 15. Filter; 16. Crude ethylene glycol tank; 17. Condenser; 18. Recycled ethylene glycol tank. DETAILED DESCRIPTION

[0025] In order to make the technical problems, technical solutions and beneficial effects to be solved by this application clearer, the technical solutions in the embodiments of this application will be further described in detail below in conjunction with the drawings in the embodiments of this application. It should be understood that the specific embodiments described herein are only used to explain this application and are not used to limit the technical solutions of this application. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0026] It should be noted that when a component is referred to as being "fixed to" or "disposed on" another component, it may be directly or indirectly located on the other component. When a component is referred to as being "connected to" another component, it may be directly or indirectly connected to the other component. The directions or positions indicated by the terms "upper", "lower", "left", "right", "front", "back", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc. are based on the directions or positions shown in the accompanying drawings and are only for the convenience of description and should not be construed as limitations on the present technical solution.

[0027] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features. "Multiple" means two or more, unless otherwise clearly and specifically defined.

[0028] The device uses liquid ethylene glycol as a kettle cleaning agent, which can efficiently clean impurities such as melt residues, coke, and carbon black remaining on the reactor and internal components at a relatively low temperature, and realize the recycling and recovery of ethylene glycol kettle cleaning liquid.

[0029] Example 1

[0030] This application Figure 1 As shown, the present application provides a kettle washing device for a vertical melt polycondensation reactor, including a reactor system, a slurry separation system A, an ethylene glycol circulation system B, an ethylene glycol reflux system C, a plurality of valves 3, etc. used in conjunction with each other.

[0031] The reactor system includes a melt distributor 2 at the top, a vertical shell 5 in the middle and a conical bottom shell 9 at the bottom. A film distributor 6 and a falling film element 7 are arranged inside the top of the vertical shell 5, a ribbon stirrer 8 is arranged in the conical bottom shell 9, and a discharge pipe 10 is connected to the bottom of the conical bottom shell 9. The melt distributor 2 is connected to the feed pipe 1, and a valve 1 301 is arranged on the feed pipe 1; a melt pipe is arranged in the melt distributor 2, which is connected to the film distributor 6 at the top of the vertical shell 5, and the film distributor 6 is arranged around the falling film element 7 in a ring-shaped distribution; a vacuum gas pipe 4 and a valve 303 are arranged outside the three-dimensional shell 5 near the top; a valve 4 304 is arranged on the discharge pipe 10.

[0032] Combination Figure 2 and Figure 3 , the specific settings of each system and its coordination relationship are as follows:

[0033] The feed pipe between valve one 301 and melt distributor 2 is connected to the circulation pipe at position a, and valve two 302 is arranged near this position (position a); the discharge pipe between valve four 304 and conical bottom shell 9 is connected to the separation pipe at position b, and valve five 305 is arranged near this position (position b).

[0034] The inlet of the separation tube is connected to the discharge pipe 10 at position b through valve five 305, and then connected to the gear pump 11, the precipitation tank 12, the first centrifugal pump 1401, and the valve seven 307 in sequence; the outlet is connected to the circulation pipe at position e, and then connected to the ethylene glycol circulation system. The bottom of the precipitation tank 12 is provided with a first insoluble material discharge pipe 1301 and a valve six 306.

[0035] The inlet of the circulation pipe is connected to position d at the bottom of the middle vertical shell 5, and is subsequently connected to valve eight 308, the second centrifugal pump 1402, valve nine 309, the filter 15, and valve thirteen 313 in sequence, and finally connected to the feed pipe 1 at position a through valve two 302 at the outlet.

[0036] The ethylene glycol reflux system C includes a valve 10 310, a third centrifugal pump 1403, a crude ethylene glycol tank 16, a condenser 17, a recycled ethylene glycol tank 18 and an ethylene glycol reflux pipe.

[0037] The inlet of the reflux pipe is connected to the circulation pipe at position f, and is subsequently connected in sequence to the third centrifugal pump 1403, the crude ethylene glycol tank 16, the condenser 17, the recycled ethylene glycol tank 18, the fourth centrifugal pump 1404, and the valve twelve 312. The outlet is connected to the circulation pipe at position i and is subsequently connected to the ethylene glycol circulation system.

[0038] The inlet pipe and the outlet pipe of the crude ethylene glycol tank 16 are both arranged above the tank body, and a second insoluble material discharge pipe 1302 and a valve 11 311 are arranged at the bottom.

[0039] The inlet pipe of the ethylene glycol vapor of the condenser 17 is arranged at the top, and the outlet pipe of the ethylene glycol liquid is arranged at the bottom.

[0040] The inlet pipe of the recycled ethylene glycol tank 18 is arranged at the top, and the outlet pipe is arranged at the bottom.

[0041] The above device can realize operations in the following multiple states.

[0042] (1) Ethylene glycol circulation kettle washing:

[0043] Close the inlet valve 1 301 and the outlet valve 4 304, open the valve 2 302 and the valve 12 312, open the fourth centrifugal pump 1404, inject the ethylene glycol in the recycled ethylene glycol tank 18 into the reactor system, make the ethylene glycol liquid level higher than the bottom of the vertical shell 5 (position d), and stabilize the pressure in the reactor system by regulating the valve 3 303. After the ethylene glycol liquid level is stabilized, close the valve 12 312 and the fourth centrifugal pump 1404 to stop the injection of recycled ethylene glycol, open the valve 8 308, the valve 9 309 and the valve 13 313, and open the second centrifugal pump 1402 to start the circulation of the ethylene glycol solution to wash the kettle.

[0044] During the circulating kettle washing process, ethylene glycol flows from the feed pipe 1 of the reactor system through the melt distributor 2, the film distributor 6, and the falling film element 7 in sequence. Under the combined effects of physical scouring and chemical alcoholysis, the polyester material adhering to the inner wall of the pipe, the reactor and the internal components is cleaned.

[0045] During the circulating kettle washing process, the ribbon agitator 8 does not operate, and the conical bottom shell 9 is used as a primary precipitation tank. Under certain conditions, the ethylene glycol solution can dissolve the small molecular polyester material and bring it to the conical bottom shell 9, and can also wash the gel and carbon black solid impurities adhering to the inner wall of the pipeline, the reactor and the internal components to the conical bottom shell 9. Therefore, the initial stratification is completed in the conical bottom shell 9, including the ethylene glycol solution on the upper layer and the insoluble materials at the bottom.

[0046] During the circulating kettle washing process, the ethylene glycol solution on the top of the conical bottom shell 9 begins to circulate through the pipeline, passes through the valve eight 308, the second centrifuge 1402 and the valve nine 309, and passes through the filter 15 under the driving action of the centrifuge to separate the insoluble materials, gel and carbon black in the ethylene glycol solution. The ethylene glycol solution flowing out of the filter 15 passes through the valve thirteen 313 and the valve two 302 in turn, and enters the reactor again for the kettle washing operation.

[0047] During the cycle tank washing process, ethylene glycol flows into the reactor from the reactor feed pipe (position a), and after the reactor undergoes the tank washing process, it flows out from the bottom of the vertical shell (position d). Figure 1 , Figure 3 As shown, the circulation path of ethylene glycol is: defikad.

[0048] In the process of circulating kettle washing, in order to ensure the liquid state and efficiency of ethylene glycol kettle washing liquid, it is kept in a high-temperature liquid state. The kettle washing temperature is preferably controlled at 150~200℃.

[0049] In the process of circulating kettle washing, in order to ensure that the ethylene glycol washing liquid has a certain physical flushing effect on the reactor structure during the flow process, the circulation flow rate of ethylene glycol should be guaranteed. The circulation flow rate of ethylene glycol is set to 30~100kg / min.

[0050] In the circulating kettle washing process, in order to ensure the cleaning efficiency of the ethylene glycol kettle washing solution, an appropriate amount of catalyst can be added to the ethylene glycol solution to promote alcoholysis. Preferably, zinc acetate, sodium carbonate and other catalysts that are conducive to polyester alcoholysis can be added.

[0051] During the circulating kettle washing process, when the ethylene glycol liquid level in the reactor is low, the valve twelve 312 and the fourth centrifugal pump 1404 should be opened in time to replenish the ethylene glycol in the circulating system.

[0052] (2) Slurry separation:

[0053] After the kettle washing operation begins, when some insoluble materials begin to accumulate in the conical bottom shell 9, the slurry separation system is turned on. The ribbon agitator 8 is turned on, and the valve five 305 and the valve seven 307, the gear pump 11, and the first centrifugal pump 1401 are opened at the same time. The ethylene glycol solution and insoluble materials discharged from the conical bottom shell 9 pass through the valve five 305 and flow into the sedimentation tank 12 for separation under the action of the gear pump 11. The upper layer of ethylene glycol solution separated in the sedimentation tank 12 is connected to the ethylene glycol circulation system through a pipeline.

[0054] During the slurry separation process, the ethylene glycol solution and insoluble materials flow out from the bottom of the reactor conical bottom shell 9 (position b), and flow into the ethylene glycol circulation system pipeline (position e) after passing through valve five 305, gear pump 11, sedimentation tank 12, first centrifugal pump 1401 and valve seven 307. Then the ethylene glycol solution enters the circulation system to continue the kettle washing operation. Figure 1 , Figure 3 As shown, the circulation path of ethylene glycol is: bcefikab.

[0055] During the slurry separation process, the ribbon agitator 8 needs to be opened to clean the conical bottom shell 9 and the screw agitator 8, and at the same time, it is also beneficial to discharge the insoluble materials in the conical bottom shell out of the reactor.

[0056] In the slurry separation process, in order to ensure the flow efficiency of the ethylene glycol solution and the insoluble material, a gear pump 11 is used to drive them. Preferably, a spur gear, helical gear or herringbone gear melt pump is selected.

[0057] (3) Ethylene glycol reflux:

[0058] When the melt distributor 2, the film distributor 6, the falling film element 7 and the ribbon stirrer 8 are fully cleaned and the kettle cleaning operation is nearly completed, the ethylene glycol reflux system is opened. The valve 13 313 is closed, and the valve 10 310 and the third centrifuge 1403 are opened at the same time to transfer the ethylene glycol solution to the crude ethylene glycol tank 16; the crude ethylene glycol tank 16 allows the ethylene glycol vapor to enter the condenser 17 along the pipeline through the ethylene glycol in the evaporation tank, and condenses into ethylene glycol liquid under the action of the condenser, and flows into the recycled ethylene glycol tank 18.

[0059] During the ethylene glycol reflux process, in order to ensure the kettle washing effect, the fourth centrifugal pump 1404 and the valve twelve 312 are opened to inject the ethylene glycol liquid in the recycled ethylene glycol tank 18 into the reactor system again for washing.

[0060] During the ethylene glycol reflux process, ethylene glycol has two circulation paths: (1) ethylene glycol flows out from the vertical shell, and its circulation path is: defghmjikad. (2) ethylene glycol flows out from the conical bottom shell, and its circulation path is: bcefghmjikab.

[0061] During the ethylene glycol reflux process, the ethylene glycol solution pipeline enters the crude ethylene glycol tank 16 from above, and the ethylene glycol vapor leaves the crude ethylene glycol tank 16 from above.

[0062] The crude ethylene glycol tank 16 is equipped with an ethylene glycol evaporator, which can heat the ethylene glycol solution to above the boiling point and leave the crude ethylene glycol tank 16 in the form of ethylene glycol vapor.

[0063] An insoluble material discharge pipeline 17 and a valve 12 312 are provided below the crude ethylene glycol tank 16 for periodically discharging the insoluble material produced during the evaporation of the crude ethylene glycol solution.

[0064] During the ethylene glycol reflux process, the ethylene glycol liquid condensed by the condenser 19 enters the recycled ethylene glycol tank 18 from the top through a pipeline, and the ethylene glycol liquid leaves the recycled ethylene glycol tank 18 from the bottom through a pipeline.

[0065] The liquid levels of the crude ethylene glycol tank 16 and the recycling tank 18 are flexibly set to ensure the collection and replenishment of ethylene glycol during the reflux process. Preferably, the liquid levels of the crude ethylene glycol tank 16 and the recycling ethylene glycol tank 18 are maintained between 1 / 3 and 2 / 3.

[0066] (4) Ethylene glycol discharge:

[0067] When the solution flowing into the sedimentation tank 12 is clear and not turbid, the kettle washing operation is completed and the ethylene glycol needs to be discharged from the reactor system. Close the fourth centrifugal pump 1404, valve 12 312 and valve 2 302 to stop the ethylene glycol liquid from flowing into the reactor. Close valve 8 308, the second centrifuge 1402 and valve 9 309 to stop the ethylene glycol liquid from flowing out of the vertical shell 5. Turn on the ribbon agitator 8 to allow the ethylene glycol solution in the conical bottom shell 9 of the reactor to completely flow out from the bottom outlet.

[0068] During the ethylene glycol discharge process, the ethylene glycol is stored in the crude ethylene glycol tank 16 and the recycled ethylene glycol tank 18 for later use. Figure 1 , 3 As shown, the flow path of ethylene glycol is: bcefghm.

[0069] After the ethylene glycol solution in the conical bottom shell 9 is completely discharged, the valve 5 305 is closed to keep the reactor airtight, and the temperature of the reactor is increased to evaporate the residual ethylene glycol in the reactor, and the vacuum pipe is opened to keep the reactor in a negative pressure state, and the ethylene glycol vapor is extracted, and an airtightness test is performed. The temperature of the reactor system is maintained between 200 and 260°C, and the vacuum degree is maintained within 100Pa.

[0070] When the vacuum degree remains stable, it indicates that the ethylene glycol in the reactor has been completely extracted and the air tightness is good, that is, the kettle cleaning is completed and the melt polycondensation production of polyester materials can be carried out.

[0071] The above-mentioned embodiments only express several feasible implementation methods of the present invention, and the description is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention, and the embodiments are not used to limit the scope of protection in the claims of the present invention. For ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, and all equivalent implementations or changes that do not depart from the present invention should be included in the technology of the present invention.

Claims

1. A kettle washing device for cleaning a vertical melt polycondensation reactor, used in conjunction with a vertical melt polycondensation reactor, the vertical melt polycondensation reactor comprising a feed pipe, a vertical shell and a discharge pipe, the feed pipe is connected from the top of the vertical shell, and the discharge pipe is connected from the bottom of the vertical shell, characterized in that: It also includes a slurry separation system, an ethylene glycol circulation system and an ethylene glycol reflux system. The circulation pipe inlet of the ethylene glycol circulation system is connected to the bottom of the vertical shell, and the outlet is connected to the feed pipe. The slurry separation system comprises a separation pipe, the inlet of the separation pipe is connected to the discharge pipe, and the outlet of the separation pipe is connected to the circulation pipe. The inlet and outlet of the reflux pipe of the ethylene glycol reflux system are respectively connected to different positions of the circulation pipe, and the outlet is close to one end of the feed pipe.

2. The kettle washing device for cleaning a vertical melt polycondensation reactor according to claim 1, characterized in that: A gear pump, a sedimentation tank and a first centrifugal pump are arranged in sequence along the separation pipe. The gear pump is close to one end of the discharge pipe. Valves are arranged on the pipelines between the gear pump and the discharge pipe, and between the first centrifugal pump and the circulation pipe.

3. The kettle washing device for cleaning a vertical melt polycondensation reactor according to claim 2, characterized in that: The precipitation tank is connected with a first insoluble matter discharge pipe.

4. The kettle washing device for cleaning a vertical melt polycondensation reactor according to claim 1, characterized in that: A second centrifugal pump and a filter are arranged in sequence along the circulation pipe. The centrifugal pump is close to the vertical shell, and the filter is close to the feed pipe. Valves are arranged on the pipelines between the centrifugal pump and the bottom of the vertical shell, the centrifugal pump and the filter, and the filter and the feed pipe.

5. The kettle washing device for cleaning a vertical melt polycondensation reactor according to claim 1, characterized in that: A third centrifugal pump, a crude ethylene glycol tank, a condenser, a recycled ethylene glycol tank, and a fourth centrifugal pump are sequentially arranged along the reflux pipe. The inlet and outlet of the crude ethylene glycol tank are both located above the tank body; the inlet of the condenser is arranged at the top; the inlet of the recycled ethylene glycol tank is located above the tank body, and the outlet is located below the tank body; valves are arranged on the circulation pipe between the third centrifugal pump and the circulation pipe, the fourth centrifugal pump and the circulation pipe, and the two interfaces between the third centrifugal pump, the fourth centrifugal pump and the circulation pipe.

6. A kettle washing device for cleaning a vertical melt polycondensation reactor according to claim 5, characterized in that: The crude ethylene glycol tank is connected with a second insoluble matter discharge pipe.

7. A kettle washing device for cleaning a vertical melt polycondensation reactor according to any one of claims 1 to 6, characterized in that: A melt distributor is arranged on the top of the vertical shell, a feed pipe is connected to the melt distributor, a film distributor and a falling film element are arranged below the melt distributor; a conical bottom shell is arranged at the bottom of the vertical shell, a spiral ribbon agitator is distributed in the conical bottom shell, and a discharge pipe is connected to the bottom outlet of the conical bottom shell.

8. The kettle washing device for cleaning a vertical melt polycondensation reactor according to claim 7, characterized in that: The vertical shell is connected with a vacuum gas pipeline.

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