Polyester production device

Abstract

The utility model relates to a polyester production device, including an ethylene glycol process tower, a recycled ethylene glycol tank, an ethylene glycol evaporation tank, a slurry recycled ethylene glycol tank, a slurry recycled tank, a first circulation pump, a second circulation pump, a first pipeline, a second pipeline, a third pipeline, a fourth pipeline, a first cleaning pipeline, a second cleaning pipeline, a third cleaning pipeline, and a fourth cleaning pipeline. The ethylene glycol process tower is connected to the recycled ethylene glycol tank through the first pipeline; the ethylene glycol process tower is connected to the ethylene glycol evaporation tank through the second pipeline; the first cleaning pipeline is connected to the first pipeline and the second pipeline; the second cleaning pipeline is connected to the second pipeline and the slurry recycled ethylene glycol tank; one end of the third cleaning pipeline is connected to the first pipeline, and the other end of the third cleaning pipeline is connected to the third pipeline; one end of the fourth cleaning pipeline is connected to the third cleaning pipeline, and the other end of the fourth cleaning pipeline is connected to the fourth pipeline. The device provided by the utility model can effectively clean blocked pipelines, stabilize production, and improve cleaning efficiency.

Description

Technical Field

[0001] The utility model relates to a polyester production device. Background Art

[0002] In the high shrinkage polyester production process, the sources of ethylene glycol in the recycled ethylene glycol tank mainly include the production from the ethylene glycol process tower, the pre-ethylene glycol hot well and the final polyethylene glycol hot well. The process tower is mainly used for the ethylene glycol produced in the distillation system. When the temperature is controlled at about 180°C, a large amount of water and some impurities with low boiling points can be evaporated. The main function is to reduce the water content of ethylene glycol and evaporate impurities with low boiling points. The distilled ethylene glycol and impurities with high boiling points will be sent to the ester reactor 1 and ester reactor 2 for reaction. Part of the distilled ethylene glycol is produced to the slurry reuse ethylene glycol tank to control the liquid level of the process tower.

[0003] During the production process of high-shrinkage semi-dispersible products, a large amount of auxiliary agents are added, and some of them are easily crystallized and attached to the wall of the pipeline after being extracted by the vacuum system. The ethylene glycol extracted from the pre-secondary and final polymerization vacuum systems is captured by the scraper condenser and enters the hot well. There are many impurities and it is mixed with some auxiliary materials that are easy to crystallize. The ethylene glycol is relatively turbid, which makes the pre-secondary and final polymerization hot well production pipelines easy to be blocked; the ethylene glycol impurities in the ethylene glycol slurry tank are affected by its source. The ethylene glycol small particles in the tank have a lot of suspended impurities, and it appears as a slurry white opaque liquid. After the device runs for a long time, the slurry pipeline is gradually blocked. Because there are many elbows and pipe fittings in the above pipelines, it is difficult to disassemble and clean. When the pipeline is steam-purged, the scaling on the pipe wall becomes dry and not easy to peel off, and the purging effect is not good. If the pipeline blockage is not handled in time, the situation will worsen, and there may even be a flow interruption. In order to stabilize production, it needs to be handled in time. Utility Model Content

[0004] The utility model aims to provide an improved polyester production device.

[0005] In order to achieve the above purpose, the technical solution adopted by the utility model is:

[0006] A polyester production device comprises an ethylene glycol process tower, a recycled ethylene glycol tank, an ethylene glycol evaporator, a slurry recycled ethylene glycol tank, a slurry prepared tank, a first circulation pump, a second circulation pump, a first pipeline, a second pipeline, a third pipeline, a fourth pipeline, a first cleaning pipeline, a second cleaning pipeline, a third cleaning pipeline, and a fourth cleaning pipeline. The ethylene glycol process tower is connected to the recycled ethylene glycol tank through the first pipeline, and a first valve and a second valve are arranged on the first pipeline; the ethylene glycol process tower is connected to the ethylene glycol evaporator through the second pipeline, and a third valve and a fourth valve are arranged on the second pipeline; the first cleaning pipeline is connected to the first pipeline and the second pipeline, and a fifth valve is arranged on the first cleaning pipeline; the second cleaning pipeline is connected to the second pipeline and the slurry recycled ethylene glycol tank, and a sixth valve is arranged on the second cleaning pipeline;

[0007] The ethylene glycol tank for slurry recycling is connected to the slurry mixing tank through a third pipeline, the first circulation pump is arranged on the third pipeline, the ethylene glycol tank for slurry recycling is connected to the second circulation pump through a fourth pipeline, the seventh valve is arranged on the fourth pipeline;

[0008] One end of the third cleaning pipeline is connected to the portion between the first valve and the second valve on the first pipeline, and the other end of the third cleaning pipeline is connected to the third pipeline. An eighth valve is arranged on the third cleaning pipeline.

[0009] One end of the fourth cleaning pipeline is connected to the third cleaning pipeline, and the other end of the fourth cleaning pipeline is connected to the fourth pipeline. A ninth valve is arranged on the fourth cleaning pipeline.

[0010] In some embodiments, the device further includes a fifth cleaning pipeline, the fifth cleaning pipeline is connected to the slurry recycling ethylene glycol tank and the third pipeline, and the fifth cleaning pipeline is provided with a tenth valve.

[0011] In some embodiments, the device further comprises a sixth cleaning pipeline, and opposite ends of the sixth cleaning pipeline are connected to the third pipeline.

[0012] In some embodiments, the sixth cleaning pipeline is in a straight U shape.

[0013] In some embodiments, a third circulation pump is further provided on the first pipeline, and the third circulation pump is located between the ethylene glycol process tower and the first valve.

[0014] In some embodiments, a fourth circulation pump is further provided on the second pipeline, and the fourth circulation pump is located between the recycled ethylene glycol tank and the third valve.

[0015] In some embodiments, one end of the first cleaning pipeline is connected to the side of the third valve on the first pipeline away from the fourth circulation pump, and the other end of the first cleaning pipeline is connected to the side of the second valve on the first pipeline away from the ethylene glycol process tower.

[0016] In some embodiments, the third pipeline includes a first section and a second section, the first section is connected to the slurry preparation tank and the first circulation pump, the second section is connected to the first circulation pump and the slurry recycling ethylene glycol tank, and the first section is provided with an eleventh valve, a twelfth valve, a thirteenth valve, and a fourteenth valve.

[0017] In some embodiments, the device also includes a first backup pipeline, one end of the first backup pipeline is connected to the portion between the eleventh valve and the twelfth valve on the third pipeline, the other end of the first backup pipeline is connected to the portion between the first circulation pump and the eleventh valve on the third pipeline, and a fifteenth valve is arranged on the first backup pipeline.

[0018] In some embodiments, the device also includes a second backup pipeline, one end of the second backup pipeline is connected to the portion between the thirteenth valve and the twelfth valve on the third pipeline, the other end of the second backup pipeline is connected to the portion between the fourteenth valve and the slurry mixing tank on the third pipeline, and a sixteenth valve is arranged on the second backup pipeline.

[0019] Due to the application of the above technical solution, the utility model has the following advantages compared with the prior art:

[0020] The polyester production device provided by the utility model can effectively clean blocked pipelines by arranging the first cleaning pipeline, the second cleaning pipeline, the third cleaning pipeline and the fourth cleaning pipeline, thereby avoiding interruption of process medium caused by pipeline blockage and stabilizing production; the cleaning efficiency is improved, and cleaning methods such as disassembly and cleaning, steam purging and pipeline cutting cleaning can be replaced; online product indicators will not be affected, and foreign matter will not be introduced into the production system; the operation process is simple, easy to operate, the pipeline is closed, and the safety factor is low. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Attached Figure 1 A schematic diagram of the structure of a polyester production device provided by the utility model;

[0022] Attached Figure 2 A schematic structural diagram of a hot washing process 1 of a polyester production device provided by the utility model;

[0023] Attached Figure 3 A schematic structural diagram of the second hot washing process of the polyester production device provided by the utility model;

[0024] Attached Figure 4 A schematic diagram of the structure of the hot washing process 3 of the polyester production device provided by the utility model;

[0025] Attached Figure 5 This is a schematic diagram of the overall structure of the polyester production device provided by the utility model.

[0026] In the above attached figure:

[0027] 1-the third valve; 2-the fourth valve; 3-the sixth valve; 4-the fifth valve; 5-the first valve; 6-the seventh valve; 7-the ninth valve; 8-the fifteenth valve; 9-the eleventh valve; 10-the twelfth valve, 11-the sixteenth valve; 12-the thirteenth valve; 13-the fourteenth valve; 14-the eighth valve; 15-the tenth valve; 16-the second valve; 17-the first pipeline; 18-the second pipeline; 19-the third pipeline, 191-the first section, 192-the second section; 20-the fourth pipeline; 21-the first cleaning pipeline; 22-the second cleaning pipeline; 23-the third cleaning pipeline; 24- The fourth cleaning pipeline; 25-the fifth cleaning pipeline; 26-the sixth cleaning pipeline; 27-the fifth pipeline; 28-the first circulation pump; 29-the second circulation pump; 30-the third circulation pump; 31-the fourth circulation pump; 32-ethylene glycol process tower; 33-the recycled ethylene glycol tank; 34-ethylene glycol evaporation tank; 35-the slurry recycling ethylene glycol tank; 36-the slurry tank; 37-ethylene glycol scraper condenser; 38-ethylene glycol hot well; 39-ester reactor one; 40-ester reactor two; 41-the first spare pipeline; 42-the second spare pipeline; 43-ethylene glycol supply unit. DETAILED DESCRIPTION

[0028] The technical solution of the utility model will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0029] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0030] See also Figures 1 to 5 The polyester production device shown includes an ethylene glycol process tower 32, a recycled ethylene glycol tank 33, an ethylene glycol evaporation tank 34, a slurry recycled ethylene glycol tank 35, a slurry tank 36, a first circulation pump 28, a second circulation pump 29, an ethylene glycol scraper condenser 37, an ethylene glycol hot well 38 (prepolymerization, final polymerization), an ester reactor 1, an ester reactor 2, a first pipeline 17, a second pipeline 18, a third pipeline 19, a fourth pipeline 20, a first cleaning pipeline 21, a second cleaning pipeline 22, a third cleaning pipeline 23, and a fourth cleaning pipeline 24, wherein:

[0031] The ethylene glycol process tower 32 is connected to the recycled ethylene glycol tank 33 through the first pipeline 17, and the first pipeline 17 is provided with a first valve 5 and a second valve 16; the ethylene glycol process tower 32 is connected to the ethylene glycol evaporation tank 34 through the second pipeline 18, and the second pipeline 18 is provided with a third valve 1 and a fourth valve 2. The ethylene glycol distilled by the ethylene glycol process tower 32 enters the slurry preparation recycled ethylene glycol tank 35, and can be directly pumped into the production system for slurry preparation. Ethylene glycol will not bring in impurities when entering the production system, and the temperature is as high as 180°C, with a good hot washing effect.

[0032] The first cleaning pipeline 21 is connected to the first pipeline 17 and the second pipeline 18, wherein one end of the first cleaning pipeline 21 is connected to a side of the third valve 1 on the first pipeline 17 away from the fourth circulation pump 31, and the other end of the first cleaning pipeline 21 is connected to a side of the second valve 16 on the first pipeline 17 away from the ethylene glycol process tower 32; a fifth valve 4 is provided on the first cleaning pipeline 21.

[0033] The second cleaning pipeline 22 is connected to the second pipeline 18 and the ethylene glycol tank 35 for pulp recycling. The second cleaning pipeline 22 is provided with a sixth valve 3, see Figure 1 One end of the second cleaning pipeline 22 is connected to the side of the fourth valve 2 on the second pipeline 18 away from the ethylene glycol evaporation tank 34, and the other end of the second cleaning pipeline 22 is connected to the slurry recycling ethylene glycol tank 35.

[0034] The slurry recycling glycol tank 35 is connected to the slurry recycling tank 36 through the third pipeline 19, and the third pipeline 19 is provided with a first circulation pump 281. Referring to the figure, the third pipeline 19 includes a first section 191 and a second section 192. The first section is connected to the slurry recycling tank 36 and the first circulation pump 28, and the second section 192 is connected to the first circulation pump 28 and the slurry recycling glycol tank 35. The first section 191 is provided with an eleventh valve 9, a twelfth valve 10, a thirteenth valve 12, and a fourteenth valve 13.

[0035] The high-temperature material is ethylene glycol, which is evaporated from the esterification reactor under high temperature and enters the ethylene glycol process tower 32, which provides the distilled high-temperature material.

[0036] The device also includes a first backup pipeline 41, one end of the first backup pipeline 41 is connected to the portion between the eleventh valve 9 and the twelfth valve 10 set on the third pipeline 19, and the other end of the first backup pipeline 41 is connected to the portion between the first circulation pump 28 and the eleventh valve 9 on the third pipeline 19, and the fifteenth valve 8 is set on the first backup pipeline 41.

[0037] The device also includes a second backup pipeline 42, one end of the second backup pipeline 42 is connected to the portion between the thirteenth valve 12 and the twelfth valve 10 on the third pipeline 19, the other end of the second backup pipeline 42 is connected to the portion between the fourteenth valve 13 and the slurry mixing tank 36 on the third pipeline 19, and the sixteenth valve 11 is arranged on the second backup pipeline 42.

[0038] One end of the third cleaning pipeline 23 is connected to the portion between the first valve 5 and the second valve 16 on the first pipeline 17 (a three-way connection is provided at the connection point), and the other end of the third cleaning pipeline 23 is connected to the portion between the eleventh valve 9 and the twelfth valve 10 on the third pipeline 19 (a three-way connection is provided at the connection point), and the eighth valve 14 is provided on the third cleaning pipeline 23, and the eighth valve 14 is close to the eleventh valve 9.

[0039] The slurry recycling ethylene glycol tank 35 is connected to the second circulation pump 29 through the fourth pipeline 20 (a tee is set at the connection point), and the fourth pipeline 20 is provided with a seventh valve 6. The second circulation pump 29 is connected to the ethylene glycol hot well 38 (prepolymerization, final polymerization), and the ethylene glycol hot well 38 (prepolymerization, final polymerization) is connected to the ethylene glycol scraper condenser 37.

[0040] One end of the fourth cleaning pipeline 24 is connected to the third cleaning pipeline 23 (a tee is set at the connection point), and the other end of the fourth cleaning pipeline 24 is connected to the fourth pipeline 20 (a tee is set at the connection point). The fourth cleaning pipeline 24 is provided with a ninth valve 7, and the other end of the fourth cleaning pipeline 24 is close to the seventh valve 6.

[0041] The device also includes a fifth cleaning pipeline 25, one end of the fifth cleaning pipeline 25 is connected to the slurry recycling ethylene glycol tank 35 (a tee is set at the connection point), and the other end of the fifth cleaning pipeline 25 is connected to the part between the thirteenth valve 12 and the fourteenth valve 13 on the third pipeline 19 (a tee is set at the connection point), and the fifth cleaning pipeline 25 is provided with a tenth valve 15, and the tenth valve 15 is close to the sixth valve 3.

[0042] The device also includes a sixth cleaning pipeline 26, both ends of which are connected to the third pipeline 19, and the sixth cleaning pipeline 26 is in a straight U shape. Referring to the figure, one end of the sixth cleaning pipeline 26 is connected to the portion between the thirteenth valve 12 and the fourteenth valve 13 on the third pipeline 19, and the other end of the sixth cleaning pipeline 26 is connected to the portion between the eleventh valve 9 and the twelfth valve 10 on the third pipeline 19. One end of the sixth cleaning pipeline 26 is close to the thirteenth valve 12, and the other end of the fifth cleaning pipeline 25 is close to the fourteenth valve 13.

[0043] The first pipeline 17 is also provided with a third circulation pump 30, which is located between the ethylene glycol process tower 32 and the first valve 5. The second pipeline 18 is also provided with a fourth circulation pump 31, which is located between the recycled ethylene glycol tank 33 and the third valve 1. The first valve 5 is close to the third circulation pump 30, and the third valve 1 is close to the fourth circulation pump 31.

[0044] The device further includes a fifth pipeline 27 , one end of which is connected to the first pipeline 17 , and the other end of which is connected to the ethylene glycol supply unit 43 . A seventeenth valve is disposed on the fifth pipeline 27 .

[0045] See also Figure 2 When there are impurities in the first pipeline 17 and the second pipeline 18 that need to be cleaned, the specific operation steps of the hot washing process 1 are as follows:

[0046] The third valve 1 and the fourth valve 2 are closed, and then the first valve 5, the second valve 16, the fifth valve 4, and the sixth valve 3 are opened in sequence to access the pipeline between the third valve 1 and the fourth valve 2 (i.e., the first pipeline 17 and the second pipeline 18); during the operation, the tenth valve 15, the eighth valve 14, the ninth valve 7, the fifteenth valve 8, and the sixteenth valve 11 are closed, and the seventh valve 6, the eleventh valve 9, the twelfth valve 10, the thirteenth valve 12, and the fourteenth valve 13 are opened. The flow direction is: the high-temperature ethylene glycol heat medium flow starts from the ethylene glycol process tower 32, and the power provided by the third circulating pump 30 makes the high-temperature ethylene glycol flow through the first valve 5, the second valve 16, the fifth valve 4, and the sixth valve 3 in sequence, and then flows into the ethylene glycol tank 35 for slurry reuse (the high-temperature ethylene glycol after hot washing enters the ethylene glycol tank 35 for slurry reuse). During the hot washing process, pay attention to the temperature and liquid level changes of the ethylene glycol tank 35 for slurry reuse.

[0047] See also Figure 3 When there are impurities in the fourth pipeline 20 between the seventh valve 6 and the ethylene glycol tank 35 for pulp recycling and need to be cleaned, the specific operation steps of the hot washing process 2 are as follows:

[0048] The seventh valve 6 is closed, and then the first valve 5 and the ninth valve 7 are opened in sequence, wherein the second valve 16, the fifth valve 4, the sixth valve 3, the tenth valve 15, the eighth valve 14, the fifteenth valve 8, and the sixteenth valve 11 are closed, and the third valve 1, the fourth valve 2, the eleventh valve 9, the twelfth valve 10, the thirteenth valve 12, and the fourteenth valve 13 are opened, and the flow direction is: the high-temperature ethylene glycol heat medium flow starts from the ethylene glycol process tower 32, and the power provided by the third circulating pump 30 makes the high-temperature ethylene glycol flow through the third cleaning pipeline 23, the fourth cleaning pipeline 24, and the fourth pipeline 20 to the slurry recycling ethylene glycol tank 35 (wherein it flows through the first valve 5 and the ninth valve 7), see the figure. The hot wash process 2 and the hot wash process 1 cannot be operated at the same time.

[0049] During normal operation, the fifteenth valve 8 and the sixteenth valve 11 are closed.

[0050] See also Figure 4 When there are impurities in the pipeline between the eleventh valve 9 and the twelfth valve 10 and the pipeline between the thirteenth valve 12 and the fourteenth valve 13 and they need to be cleaned, the specific operation steps of the hot washing process three are as follows:

[0051] First, open the fifteenth valve 8, close the eleventh valve 9 and the twelfth valve 10; then open the sixteenth valve 11, close the thirteenth valve 12 and the fourteenth valve 13; then, open the first valve 5, the eighth valve 14, and the tenth valve 15, and conduct the pipelines at the rear end of the eleventh valve 9, the front end of the twelfth valve 10, and the rear end of the thirteenth valve 12, wherein the sixth valve 3, the fifth valve 4, the ninth valve 7, and the second valve 16 are closed, and the third valve 1, the fourth valve 2, and the seventh valve 6 are opened. The high-temperature ethylene glycol heat medium flow starts from the ethylene glycol process tower 32, and the power provided by the third circulating pump 30 makes the high-temperature ethylene glycol flow through the third cleaning pipeline 23, the eighth valve 14, the pipeline between the eighth valve 14 and the twelfth valve 10, the sixth cleaning pipeline 26, the pipeline between one end of the sixth cleaning pipeline 26 and the fourteenth valve 13, and the fifth cleaning pipeline 25, and flows into the ethylene glycol tank 35 for slurry reuse.

[0052] Figure 1 In the figure, a represents the pre-gas phase line 1, b represents the pre-gas phase line 2, c represents the pre-gas phase line 3, and d represents the ethylene glycol injection pump. Figure 5 The middle circle indicates that a tee is required.

[0053] In the polyester production device in this example, the valves involved are not pneumatic valves. The anti-mistook measures of the interlocking of the pneumatic valves can prevent people from accidentally discharging high-temperature ethylene glycol and scalding people. The high-temperature ethylene glycol is discharged after being cooled, which reduces the risk of scalding caused by direct sampling of high-temperature materials and ensures personal safety.

[0054] In the polyester production device of this example, high-temperature ethylene glycol with a temperature of up to 180°C is used as the cleaning medium for hot washing of the pipeline. The auxiliary agent crystals will melt, and the wall-hanging materials will become soft, which can completely peel off and wash away the wall-hanging scale in the pipeline, thereby improving the cleaning efficiency. The polyester production device of this example can handle pipeline blockage through hot washing, which can replace manual disassembly and cleaning, and can effectively clean the wall-hanging materials in the pipeline wall, reducing the workload of manual disassembly and cleaning.

[0055] The above embodiments are only for illustrating the technical concept and features of the utility model, and their purpose is to enable people familiar with the technology to understand the content of the utility model and implement it accordingly, and they cannot be used to limit the protection scope of the utility model. Any equivalent changes or modifications made according to the spirit of the utility model should be included in the protection scope of the utility model.

Claims

1. A polyester production device, characterized in that: It includes an ethylene glycol process tower, a recycled ethylene glycol tank, an ethylene glycol evaporator, a slurry recycled ethylene glycol tank, a slurry prepared tank, a first circulating pump, a second circulating pump, a first pipeline, a second pipeline, a third pipeline, a fourth pipeline, a first cleaning pipeline, a second cleaning pipeline, a third cleaning pipeline, and a fourth cleaning pipeline. The ethylene glycol process tower is connected to the recycled ethylene glycol tank through the first pipeline, and a first valve and a second valve are arranged on the first pipeline; the ethylene glycol process tower is connected to the ethylene glycol evaporator through the second pipeline, and a third valve and a fourth valve are arranged on the second pipeline; the first cleaning pipeline is connected to the first pipeline and the second pipeline, and a fifth valve is arranged on the first cleaning pipeline; the second cleaning pipeline is connected to the second pipeline and the slurry recycled ethylene glycol tank, and a sixth valve is arranged on the second cleaning pipeline; The ethylene glycol tank for slurry recycling is connected to the slurry mixing tank through a third pipeline, the first circulation pump is arranged on the third pipeline, the ethylene glycol tank for slurry recycling is connected to the second circulation pump through a fourth pipeline, the seventh valve is arranged on the fourth pipeline; One end of the third cleaning pipeline is connected to the portion between the first valve and the second valve on the first pipeline, and the other end of the third cleaning pipeline is connected to the third pipeline. An eighth valve is arranged on the third cleaning pipeline. One end of the fourth cleaning pipeline is connected to the third cleaning pipeline, and the other end of the fourth cleaning pipeline is connected to the fourth pipeline. A ninth valve is arranged on the fourth cleaning pipeline.

2. The polyester production device according to claim 1, characterized in that: The device also includes a fifth cleaning pipeline, which is connected to the slurry recycling ethylene glycol tank and the third pipeline, and a tenth valve is arranged on the fifth cleaning pipeline.

3. The polyester production device according to claim 2, characterized in that: The device further comprises a sixth cleaning pipeline, and opposite ends of the sixth cleaning pipeline are connected to the third pipeline.

4. The polyester production device according to claim 3, characterized in that: The sixth cleaning pipeline is in a straight U shape.

5. The polyester production device according to claim 1, characterized in that: The first pipeline is also provided with a third circulation pump, and the third circulation pump is located between the ethylene glycol process tower and the first valve.

6. The polyester production device according to claim 5, characterized in that: The second pipeline is also provided with a fourth circulation pump, and the fourth circulation pump is located between the recycled ethylene glycol tank and the third valve.

7. The polyester production device according to claim 6, characterized in that: One end of the first cleaning pipeline is connected to the side of the third valve on the first pipeline away from the fourth circulation pump, and the other end of the first cleaning pipeline is connected to the side of the second valve on the first pipeline away from the ethylene glycol process tower.

8. The polyester production device according to claim 1, characterized in that: The third pipeline includes a first section and a second section. The first section is connected to the slurry preparation tank and the first circulation pump, and the second section is connected to the first circulation pump and the slurry preparation recycling ethylene glycol tank. The first section is provided with an eleventh valve, a twelfth valve, a thirteenth valve, and a fourteenth valve.

9. The polyester production device according to claim 8, characterized in that: The device also includes a first backup pipeline, one end of which is connected to the portion between the eleventh valve and the twelfth valve on the third pipeline, and the other end of which is connected to the portion between the first circulation pump and the eleventh valve on the third pipeline. A fifteenth valve is arranged on the first backup pipeline.

10. The polyester production device according to claim 9, characterized in that: The device also includes a second backup pipeline, one end of which is connected to the portion between the thirteenth valve and the twelfth valve on the third pipeline, and the other end of the second backup pipeline is connected to the portion between the fourteenth valve and the slurry mixing tank on the third pipeline, and a sixteenth valve is arranged on the second backup pipeline.

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