High-temperature ethylene glycol flushing system of recycled polyester vacuum device

Abstract

The high-temperature ethylene glycol flushing system comprises an ethylene glycol storage tank and an ethylene glycol conveying pump, a heating medium coil pipe is installed in the ethylene glycol storage tank, and a tank body outlet in the bottom of the ethylene glycol storage tank is connected with an inlet end pipeline of the ethylene glycol conveying pump. A filter is installed on a connecting pipeline of an outlet of the tank body and the ethylene glycol conveying pump, the regenerated polyester vacuum device comprises a gas phase condenser and a cyclone separator, the outlet end of the ethylene glycol conveying pump is respectively connected to the gas phase condenser and the cyclone separator through pipelines, and the bottom of the cyclone separator is connected to the ethylene glycol storage tank through a pipeline. According to the utility model, the heated ethylene glycol is pumped to the gas phase condenser and the demister, the hot ethylene glycol is used for flushing and dissolving attachments such as oligomers in pipelines and parts, and the ethylene glycol finally flows back to the ethylene glycol storage tank, so that the effect of collecting the carried attachments is realized; the utility model can effectively solve the problem of attachment accumulation of the recycled polyester vacuum device.

Description

Technical Field

[0001] This utility model relates to the technical field of auxiliary equipment for recycled polyester production, and more specifically, to a high-temperature ethylene glycol rinsing system for a recycled polyester vacuum device. Background Technology

[0002] In the recycled polyester production process, the polycondensation section consists of only one reactor. Vacuum is a crucial system for recycled PET polyester plants, as its stability directly determines product quality and whether the reaction can be completed within the specified time.

[0003] The polycondensation process generates a large amount of mixed vapor, primarily composed of ethylene glycol vapor, along with other substances including dimethyl terephthalate (DMT), low-polymerization-degree polyethylene terephthalate (PET), and other impurities. DMT has a low flash point and is easily carried out by the ethylene glycol (EG) gas flow during the initial vacuuming stage of polycondensation. After being carried out by the gas flow, some of the low-polymerization-degree PET is cooled and precipitated in the vapor phase condenser, while the rest enters the cyclone separator via the polycondensation vacuum gas phase pipeline. During the process of the gas flow entering the cyclone separator, the entrained materials adhere to the demister and the walls of the vapor phase pipeline, causing a reduction in the inner diameter of the vapor phase condenser and blockage of the demister. This severely affects the vacuuming effect of the polycondensation section's vacuum system. If this cannot be handled promptly and effectively, it can lead to emergency production shutdowns and losses. Therefore, adding a cleaning system to the recycled polyester vacuum unit is an urgent need for stable production, hence this project. Utility Model Content

[0004] The purpose of this invention is to address the needs of the prior art by providing a high-temperature ethylene glycol flushing system for a recycled polyester vacuum device. This invention adds an ethylene glycol circulation loop system to the recycled polyester vacuum device design. Heated ethylene glycol is pumped to the vapor phase condenser and demister via an ethylene glycol transfer pump. Hot ethylene glycol is used to flush and dissolve oligomers and other deposits in the pipelines and components. The ethylene glycol ultimately flows back to the ethylene glycol storage tank, achieving the effect of collecting the deposits. This invention effectively solves the problem of deposit accumulation in recycled polyester vacuum devices.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A high-temperature ethylene glycol flushing system for a recycled polyester vacuum device is applied to the device. It includes an ethylene glycol storage tank and an ethylene glycol transfer pump. The ethylene glycol storage tank contains liquid ethylene glycol and a heat transfer coil is installed inside. An outlet is located on the bottom side wall of the tank, and this outlet is connected to the inlet of the ethylene glycol transfer pump. A filter is installed on the connection between the outlet and the pump. The recycled polyester vacuum device includes a vapor phase condenser and a cyclone separator. The bottom of the vapor phase condenser is connected to the side of the cyclone separator. The outlet of the ethylene glycol transfer pump is connected to both the vapor phase condenser and the cyclone separator via pipelines. The bottom pipeline of the cyclone separator is connected to the ethylene glycol storage tank.

[0007] Furthermore, the ethylene glycol storage tank is equipped with a stirring device, a first pipe is connected between the tank outlet and the filter, and a first valve and a second valve are installed at the tank outlet. Both the first valve and the second valve can be connected to the first pipe. The first valve and the second valve are connected in parallel, and the first valve and the second valve are not opened at the same time.

[0008] Furthermore, the first valve is installed at a higher height than the second valve.

[0009] Furthermore, a second pipe is connected between the filter and the ethylene glycol delivery pump, a demister is installed on the top pipe of the cyclone separator, a third pipe is connected to the outlet end of the ethylene glycol delivery pump, and the other end of the third pipe extends toward the recycled polyester vacuum device and branches off to connect to the top of the gas phase condenser and the top of the demister, respectively.

[0010] Furthermore, the bottom outlet of the cyclone separator is connected to a fourth pipe, the other end of which extends to connect to the top of the ethylene glycol storage tank.

[0011] Furthermore, a fifth pipe is connected to the top of the ethylene glycol storage tank, and a tail gas condenser is connected to the end of the fifth pipe.

[0012] Furthermore, a third valve is installed on the bottom side wall of the ethylene glycol storage tank. The installation height of the third valve is lower than that of the second valve. The third valve is connected to a sixth pipe, and the other end of the sixth pipe is connected to the second pipe.

[0013] Furthermore, a first pressure gauge is installed on the first pipe, a second pressure gauge is installed on the second pipe, and a third pressure gauge is installed on the third pipe.

[0014] The beneficial effects of this utility model are:

[0015] 1. This utility model adds an ethylene glycol circulation loop system to the design of a recycled polyester vacuum device. Heated ethylene glycol is pumped to the vapor phase condenser and demister by an ethylene glycol transfer pump. Hot ethylene glycol is used to flush and dissolve oligomers and other adhering substances in the pipelines and components. The dissolved adhering substances are returned to the cyclone separator with the ethylene glycol and finally returned to the ethylene glycol storage tank. Part of the adhering substances are deposited in the ethylene glycol storage tank, and the bottom of the storage tank can be cleaned periodically. The rest is filtered out of the system through a filter.

[0016] 2. This utility model can effectively solve the problem of deposits accumulating in the vacuum device for recycled polyester, and its application can significantly reduce the clogging failure rate of the vacuum device for recycled polyester. Attached Figure Description

[0017] Figure 1 This is a connection diagram of the high-temperature ethylene glycol rinsing system of a recycled polyester vacuum device in this embodiment.

[0018] Figure reference numerals: 1. Polycondensation reactor; 2. Vapor phase condenser; 3. Cyclone separator; 4. Ethylene glycol storage tank; 41. Heat medium coil; 42. Stirring device; 43. Tank outlet; 431. First valve; 432. Second valve; 44. Third valve; 5. Filter; 6. Ethylene glycol transfer pump; 7. Tail gas condenser; 8. Demister; 81. First pipeline; 82. Second pipeline; 83. Third pipeline; 84. Fourth pipeline; 85. Fifth pipeline; 86. First pressure gauge; 87. Second pressure gauge; 88. Third pressure gauge; 89. Sixth pipeline. Detailed Implementation

[0019] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0020] like Figure 1The invention illustrates a high-temperature ethylene glycol flushing system for a recycled polyester vacuum device. This system is connected to the recycled polyester vacuum device, which includes a polycondensation reactor 1, a vapor phase condenser 2, and a cyclone separator 3. The vapor phase condenser 2 is connected to the polycondensation reactor 1 to receive the mixed steam generated during the polycondensation process. The bottom of the vapor phase condenser 2 is connected to the cyclone separator 3. After the mixed steam passes through the vapor phase condenser 2 and the cyclone separator 3, the entrained material in the airflow forms deposits that gradually accumulate in the pipes and equipment, eventually causing blockages and affecting production. This invention addresses this problem by designing a high-temperature ethylene glycol flushing system for a recycled polyester vacuum device. The aforementioned issues include an ethylene glycol storage tank 4 and an ethylene glycol transfer pump 6. The ethylene glycol storage tank 4 stores liquid ethylene glycol and is equipped with a heat transfer coil 41. The heat transfer coil 41 allows the flow of heat transfer medium to heat the liquid ethylene glycol, raising its temperature to approximately 150°C. The bottom side wall of the ethylene glycol storage tank 4 has a tank outlet 43, which is connected to the inlet pipe of the ethylene glycol transfer pump 6. The ethylene glycol transfer pump 6 draws the high-temperature liquid ethylene glycol from the storage tank 4. A filter 5 is installed on the connection pipe between the tank outlet 43 and the pump 6. The filter 5 filters the drawn high-temperature liquid ethylene glycol to ensure the high-temperature ethylene glycol... To ensure the purity of the glycol liquid, in the recycled polyester vacuum device, the vapor phase condenser 2 is installed vertically, with its bottom end connected to the side of the cyclone separator 3. The outlet of the glycol transfer pump 6 is connected to both the vapor phase condenser 2 and the cyclone separator 3 via pipelines. Pure, high-temperature glycol liquid drawn from the glycol storage tank 4 is pumped to the vapor phase condenser 2 and the cyclone separator 3. The high-temperature glycol liquid dissolves deposits in the pipelines and components along the way. The deposits flow with the glycol liquid and first collect in the cyclone separator 3. Since the bottom pipeline of the cyclone separator 3 is connected to the glycol storage tank 4, the deposits eventually collect in the glycol storage tank 4, forming a cleaning loop. The deposits inside tank 4 will accumulate at the bottom of the ethylene glycol storage tank 4. A cleaning manhole is provided at the bottom of the ethylene glycol storage tank 4 for regular cleaning. During the circulation and pumping of high-temperature ethylene glycol liquid, some deposits will still be pumped out with the high-temperature ethylene glycol liquid. Therefore, it is essential to install a filter 5 on the pumping pipeline. The filter 5 can purify the high-temperature ethylene glycol liquid used for cleaning and block the deposits. The filter 5 also needs to be opened and cleaned regularly. The application of this utility model can effectively solve the problem of deposit accumulation in the vacuum device of recycled polyester. The application of this utility model can significantly reduce the clogging failure rate of the vacuum device of recycled polyester, so that the production of recycled polyester can proceed smoothly and stably.

[0021] An agitator 42 is installed inside the ethylene glycol storage tank 4. The agitator 42 stirs the ethylene glycol liquid inside the tank, ensuring it is fully heated. The agitator 42 should be positioned away from the heat transfer coil 41. A first pipe 81 connects the tank outlet 43 to the filter 5. A first valve 431 and a second valve 432 are installed at the tank outlet 43. Both valves 431 and 432 are connected to the first pipe 81. The first valve 431 and second valve 432 are connected in parallel and do not open simultaneously. The valves are designed with one valve for backup. Because the installation height of the first valve 431 is higher than that of the second valve 432, the first valve 431 is the backup valve. Valve 432 is for normal use. Under normal use, valve 431 is normally closed and valve 432 is open. As the amount of deposits from the cleaning process in ethylene glycol storage tank 4 increases, the amount of deposits carried out through valve 432 will also increase. This will increase the workload of filter 5. At this time, valve 431 can be switched to open and valve 432 closed to temporarily reduce the amount of deposits carried out. Of course, this is only a short-term solution. After batch production is completed, the deposits in ethylene glycol storage tank 4 should be cleaned in a timely manner. In the ethylene glycol storage tank 4 used in our company, valve 431 is installed at a height of 1 meter above the tank height, and valve 432 is installed at a height of 0.5 meters above the tank height, leaving a large sedimentation space below the installation height of valve 432.

[0022] A second pipe 82 connects filter 5 and ethylene glycol transfer pump 6. The filtered clean, high-temperature ethylene glycol liquid is pumped out by ethylene glycol transfer pump 6. A demister 8 is installed on the top pipe of cyclone separator 3. A third pipe 83 is connected to the outlet of ethylene glycol transfer pump 6. The other end of the third pipe 83 extends towards the recycled polyester vacuum device and branches off, connecting to the top of vapor phase condenser 2 and the top of demister 8 respectively. Through the third pipe 83, the clean, high-temperature ethylene glycol liquid is divided into two streams, entering condenser 2 and demister 8 respectively. Because condenser 2 is installed vertically and connected to cyclone separator 3, the liquid enters... The high-temperature ethylene glycol liquid entering the condenser 2 dissolves the adhering substances and flows naturally into the cyclone separator 3. Since the demister 8 is connected to the top of the cyclone separator 3, the high-temperature ethylene glycol liquid entering the demister 8 also flows into the cyclone separator 3 after dissolving the adhering substances. Finally, the ethylene glycol liquid is collected in the cyclone separator 3. The bottom outlet of the cyclone separator 3 is connected to a fourth pipe 84. The other end of the fourth pipe 84 extends to the top of the ethylene glycol storage tank 4. The ethylene glycol liquid collected in the cyclone separator 3 finally flows back into the ethylene glycol storage tank 4 through the fourth pipe 84, forming a flushing circulation line.

[0023] The top of the ethylene glycol storage tank 4 is connected to a fifth pipe 85, and the end of the fifth pipe 85 is connected to a tail gas condenser 7. During the heating of the ethylene glycol liquid, some ethylene glycol vapor will also evaporate. The fifth pipe 85 can lead the evaporated ethylene glycol vapor to the tail gas condenser 7 for condensation, and then condense it into ethylene glycol liquid and return it to the ethylene glycol storage tank 4. This can prevent the unorganized volatilization of ethylene glycol vapor and achieve the purpose of environmental protection and cost saving.

[0024] A third valve 44 is installed on the bottom side wall of the ethylene glycol storage tank 4. The installation height of the third valve 44 is lower than that of the second valve 432. The third valve 44 is connected to a sixth pipe 89, and the other end of the sixth pipe 89 is connected to the second pipe 82. The third valve 44 is a maintenance and cleaning valve. It is normally closed and is only opened during maintenance to clean the entire pipeline. The installation height of the third valve 44 is generally set at 0.2 meters above the tank height.

[0025] A first pressure gauge 86 is installed on the first pipe 81, a second pressure gauge 87 is installed on the second pipe 82, and a third pressure gauge 88 is installed on the third pipe 83. The first pressure gauge 86, the second pressure gauge 87, and the third pressure gauge 88 correspond to the pressure values ​​of the respective pipes. If the pressure of the third pressure gauge 88 is too high, it indicates that the output end of the third pipe 83 is blocked, that is, the inlet of the vapor phase condenser 2 and the demister 8 is blocked, and timely inspection and maintenance are required. If the pressure of the third pressure gauge 88 is too low, it indicates that there may be a blockage at the filter 5, and the filter 5 needs to be disassembled and cleaned in time. When the filter 5 is operating normally, the pressure difference between the first pressure gauge 86 and the second pressure gauge 87 is not large. When the filter 5 is blocked, there will be a large pressure difference change, which is one of the criteria for judging whether there is a blockage at the filter 5.

[0026] The above description is merely a preferred embodiment of this utility model. The protection scope of this utility model is not limited to the above embodiments. All technical solutions falling within the scope of this utility model's concept are protected. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principle of this utility model should also be considered within the protection scope of this utility model.

Claims

1. A high-temperature ethylene glycol rinsing system for a recycled polyester vacuum device, applied and connected to the recycled polyester vacuum device, characterized in that, The device includes an ethylene glycol storage tank (4) and an ethylene glycol transfer pump (6). The ethylene glycol storage tank (4) stores liquid ethylene glycol and is equipped with a heat transfer coil (41). The bottom side wall of the ethylene glycol storage tank (4) is provided with a tank outlet (43). The tank outlet (43) is connected to the inlet end of the ethylene glycol transfer pump (6) via a pipeline. A filter (5) is installed on the connecting pipeline between the tank outlet (43) and the ethylene glycol transfer pump (6). The recycled polyester vacuum device includes a vapor phase condenser (2) and a cyclone separator (3). The bottom end of the vapor phase condenser (2) is connected to the side of the cyclone separator (3). The outlet end of the ethylene glycol transfer pump (6) is connected to the vapor phase condenser (2) and the cyclone separator (3) via pipelines. The bottom pipeline of the cyclone separator (3) is connected to the ethylene glycol storage tank (4).

2. The high-temperature ethylene glycol rinsing system for a recycled polyester vacuum device according to claim 1, characterized in that, The ethylene glycol storage tank (4) is equipped with a stirring device (42). A first pipe (81) is connected between the tank outlet (43) and the filter (5). A first valve (431) and a second valve (432) are installed at the tank outlet (43). Both the first valve (431) and the second valve (432) are connected to the first pipe (81). The first valve (431) and the second valve (432) are connected in parallel. The first valve (431) and the second valve (432) are not opened at the same time.

3. The high-temperature ethylene glycol rinsing system for a recycled polyester vacuum device according to claim 2, characterized in that, The first valve (431) is installed at a higher height than the second valve (432).

4. The high-temperature ethylene glycol rinsing system for a recycled polyester vacuum device according to claim 2, characterized in that, A second pipe (82) is connected between the filter (5) and the ethylene glycol transfer pump (6). A demister (8) is installed on the top pipe of the cyclone separator (3). A third pipe (83) is connected to the outlet end of the ethylene glycol transfer pump (6). The other end of the third pipe (83) extends toward the recycled polyester vacuum device and branches off to connect to the top of the vapor phase condenser (2) and the top of the demister (8) respectively.

5. The high-temperature ethylene glycol rinsing system for a recycled polyester vacuum device according to claim 1, characterized in that, The bottom outlet of the cyclone separator (3) is connected to a fourth pipe (84), the other end of which extends to connect to the top of the ethylene glycol storage tank (4).

6. The high-temperature ethylene glycol rinsing system for a recycled polyester vacuum device according to claim 1, characterized in that, The top of the ethylene glycol storage tank (4) is connected to a fifth pipe (85), and the end of the fifth pipe (85) is connected to a tail gas condenser (7).

7. The high-temperature ethylene glycol rinsing system for a recycled polyester vacuum device according to claim 2, characterized in that, The bottom side wall of the ethylene glycol storage tank (4) is equipped with a third valve (44), the installation height of the third valve (44) is lower than that of the second valve (432), the third valve (44) is connected to a sixth pipe (89), and the other end of the sixth pipe (89) is connected to the second pipe (82).

8. The high-temperature ethylene glycol rinsing system for a recycled polyester vacuum device according to claim 4, characterized in that, A first pressure gauge (86) is installed on the first pipe (81), a second pressure gauge (87) is installed on the second pipe (82), and a third pressure gauge (88) is installed on the third pipe (83).

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