Online automatic flushing device for vacuum pipeline

Abstract

The utility model discloses an on-line automatic flushing device for a vacuum pipeline, which comprises a final polymerization reaction kettle, a vacuum butterfly valve, a vacuum pipeline and a vacuum system consisting of at least one group of ethylene glycol steam vacuum jet pump and an ethylene glycol spraying condenser, and a knocking mechanism is arranged on the outer wall of the vacuum pipeline. An ethylene glycol spraying mechanism is arranged in the vacuum pipeline, oligomers and solid substances adhering to the inner wall of the vacuum pipeline are loosened and fall off through the knocking mechanism, and the loosened or falling oligomers and solid substances are filtered and discharged after being subjected to high-pressure washing through the ethylene glycol spraying mechanism and flowing back along the vacuum pipeline. According to the device, substances adhered in the final polymerization vacuum pipeline can be cleaned and discharged on line under the condition that normal production is not influenced, and the inner wall of the final polymerization vacuum pipeline is clean and free of substance accumulation, so that gas in a polycondensation reaction kettle can be normally pumped out by a vacuum system, and a stable vacuum environment is provided for polycondensation reaction.

Description

Technical Field

[0001] This utility model relates to the technical field of vacuum pipeline cleaning, specifically to an online automatic flushing device for vacuum pipelines. Background Technology

[0002] Currently, in polyester production, a stable vacuum environment is required for the polycondensation reaction, making the vacuum system one of the crucial components affecting the stability of polyester production. In the Contex polyester plant, the reactor, ethylene glycol spray condenser, and vacuum system are connected via vacuum butterfly valves and vacuum pipelines. The opening degree of the vacuum butterfly valve is typically around 30-40 degrees; the smaller the opening, the smoother the vacuum pipeline. When the vacuum system extracts vapors such as ethylene glycol vapor and water vapor from the polycondensation reactor, it also carries away some oligomers and unreacted PTA powder. After being sprayed by the ethylene glycol spray condenser, some of these are carried away by the ethylene glycol, while the rest enters the vacuum pipeline connected to the vacuum system. Furthermore, the significant vacuum variation before and after the vacuum butterfly valve, with a higher vacuum after the valve causing some oligomers dissolved in ethylene glycol to precipitate, leads to the accumulation of these oligomers and solid substances on the inner wall of the vacuum pipeline. With prolonged operation of the production unit, this buildup reduces the inner diameter of the vacuum pipeline, sometimes even causing blockage. This necessitates increasingly larger openings of the vacuum butterfly valve, preventing the proper extraction of ethylene glycol vapor, water vapor, and non-condensable gases from the polycondensation reactor. Consequently, the vacuum level in the polycondensation reactor fails to meet production requirements, necessitating shutdown for cleaning and resulting in production losses. Simultaneously, the higher vacuum level in the final polycondensation reactor makes it easier to extract oligomers, making the final polycondensation vacuum pipeline more prone to blockage. Therefore, an online automatic flushing device for the final polycondensation vacuum pipeline is needed to solve the problem of blockage during production. Utility Model Content

[0003] To address certain technical problems existing in the prior art, the purpose of this application is to provide an online automatic cleaning device for vacuum pipelines. This device can clean and remove oligomers and solid substances adhering to the final polymerization vacuum pipeline online without affecting normal production. This ensures that the inner wall of the final polymerization vacuum pipeline is clean and free of oligomers and solid substances, thereby ensuring that ethylene glycol vapor, water vapor, and non-condensable gases in the polycondensation reactor can be normally extracted by the vacuum system. This provides a stable vacuum environment for the polycondensation reaction and provides a strong guarantee for the stable production of polyester.

[0004] To solve the aforementioned technical problems, this application adopts the following technical solution:

[0005] An online automatic flushing device for vacuum pipelines includes a final polymerization reactor, a vacuum butterfly valve, a vacuum pipeline, and a vacuum system consisting of at least one set of ethylene glycol vapor vacuum jet pumps and ethylene glycol spray condensers. The outer wall of the vacuum pipeline is provided with a knocking mechanism, and the vacuum pipeline is provided with an ethylene glycol spraying mechanism. Oligomers and solid substances adhering to the inner wall of the vacuum pipeline are loosened and fall off by the knocking mechanism. The loosened or fallen oligomers and solid substances are flushed under high pressure by the ethylene glycol spraying mechanism and then flow back along the vacuum pipeline and are filtered and discharged.

[0006] Preferably, the striking mechanism includes a plurality of pneumatic striking hammers disposed on the outer wall of the vacuum pipeline and a solenoid valve A for controlling the striking of the pneumatic striking hammers.

[0007] Preferably, the outer wall of the vacuum pipeline struck by the pneumatic hammer is provided with a copper thickening layer to prevent damage to the outer wall of the vacuum pipeline when struck by the pneumatic hammer.

[0008] Preferably, the ethylene glycol spraying mechanism includes an ethylene glycol spraying pipe located on the vacuum pipeline near the bend of the vacuum system, a shower-shaped ethylene glycol spraying nozzle located at one end of the ethylene glycol spraying pipe, a solenoid valve B and a flow regulating valve located on the ethylene glycol pipeline.

[0009] Preferably, both the ethylene glycol spraying mechanism and the tapping mechanism are equipped with a time relay, and the start-up time of the ethylene glycol spraying mechanism and the tapping mechanism is controlled by the time relay.

[0010] Preferably, the ethylene glycol spray nozzle is kept open to flush the pipe wall with an ethylene glycol flow rate of 2800 kg / h to 3500 kg / h, and each flushing process lasts for 1 to 3 minutes.

[0011] Preferably, the pneumatic hammer strikes the upper and lower outer walls of the vacuum pipeline simultaneously at a frequency of once every 3-5 seconds, with each striking process lasting 5-10 minutes.

[0012] Preferably, a spray circulation system is connected between the final polymerization reactor and the vacuum butterfly valve via a pipeline. Some of the oligomers and unreacted PTA powder and other solid substances in the gas extracted by the vacuum system are adsorbed by the spray circulation system and then filtered out.

[0013] Preferably, two sets of spray circulation systems are connected in series between the final polymerization reactor and the vacuum butterfly valve. The two sets of spray circulation systems are a primary spray circulation and a secondary spray circulation, respectively. The secondary spray circulation is arranged adjacent to the vacuum butterfly valve. The oligomers and solid substances removed by the tapping mechanism and the ethylene glycol spraying mechanism are filtered through the secondary spray circulation.

[0014] Preferably, the spray circulation system includes a spray condenser located between the final polymerization reactor and the vacuum butterfly valve, an ethylene glycol liquid seal tank connected to the spray condenser via a pipeline, a circulation pump located between the ethylene glycol liquid seal tank and the spray condenser, and a filter. The spray condenser, the ethylene glycol liquid seal tank, the circulation pump, and the filter are connected by pipelines to form an internal circulation pipeline.

[0015] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0016] Throughout the tapping and rinsing process, oligomers and solid substances adhering to the final polymerization vacuum pipeline can be cleaned and discharged online without affecting normal production. This ensures that the inner wall of the final polymerization vacuum pipeline is clean and free of oligomers and solid substances, thereby guaranteeing that ethylene glycol vapor, water vapor, and non-condensable gases in the polycondensation reactor can be normally extracted by the vacuum system. This effectively solves the problem of ethylene glycol vapor, water vapor, and non-condensable gases being unable to be normally extracted by the vacuum system due to the increasing adhesion of oligomers and solid substances in the vacuum pipeline of the final polycondensation reactor. This ensures that the vacuum level of the polycondensation reactor can always meet production needs, and the cleaning of the adhering substances inside the pipeline wall is also convenient. It provides a stable vacuum environment for the polycondensation reaction and provides a strong guarantee for the stable production of polyester. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the process flow of this utility model;

[0018] In the diagram: 1. Final polymerization reactor; 2. Spray circulation system; 21. Spray condenser; 22. Filter; 23. Circulation pump; 24. Ethylene glycol liquid seal tank; 3. Primary spray circulation; 4. Secondary spray circulation; 5. Vacuum pipeline; 6. Copper thickened layer; 7. Striking mechanism; 71. Solenoid valve A; 72. Pneumatic hammer; 8. Vacuum system; 9. Ethylene glycol spraying mechanism; 91. Ethylene glycol spray nozzle; 92. Flow regulating valve; 93. Ethylene glycol spray pipe; 94. Solenoid valve B; 10. Time relay; 11. Remote controller; 12. Vacuum butterfly valve. Detailed Implementation

[0019] The present application will now be further described in conjunction with the accompanying drawings and specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments.

[0020] In the description of this application, it should be understood that the terms "upper", "lower", "left", "right", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0021] The terms "first," "second," etc., used in this application are used to distinguish similar objects and not to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that embodiments of this application can be implemented in orders other than those illustrated or described herein, and the objects distinguished by "first," "second," etc., are generally of the same class, without limiting the number of objects; for example, a first object can be one or more. Furthermore, in the specification and claims, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0022] like Figure 1 As shown, an online automatic flushing device for vacuum pipelines includes a final polymerization reactor 1, a vacuum butterfly valve 12, a vacuum pipeline 5, and a vacuum system 8 consisting of at least one set of ethylene glycol vapor vacuum jet pumps and an ethylene glycol spray condenser 21. The outer wall of the vacuum pipeline 5 is provided with a knocking mechanism 7, and the bend of the vacuum pipeline 5 before entering the first-stage ethylene glycol vapor vacuum jet pump is provided with an ethylene glycol spraying mechanism 9. Oligomers and solid substances adhering to the inner wall of the vacuum pipeline 5 are loosened and fall off by the knocking mechanism 7. The loosened or fallen oligomers and solid substances are flushed by the high pressure of the ethylene glycol spraying mechanism 9 and then flow back along the vacuum pipeline 5 and are filtered and discharged.

[0023] In actual production, the vacuum system 8 typically consists of four sets of ethylene glycol vapor vacuum jet pumps and ethylene glycol spray condensers 21. The vacuum pipeline 5 is arranged in an S-shape or Z-shape with an upward inclination. The vacuum level inside the final polymerization reactor 1 is evacuated by the vacuum system 8, which consists of the ethylene glycol vapor vacuum jet pumps and ethylene glycol spray condensers 21. The vacuum value is controlled by a vacuum butterfly valve 12. Although some oligomers and unreacted PTA powder and other solid substances in the gas before entering the vacuum pipeline 5 can be carried out by the spray circulation system 2, there is still some... As the oligomers and unreacted PTA powder enter the vacuum line 5, they adhere to the tube wall. Over time, this adhesion thickens. Therefore, to facilitate the removal of these adhered oligomers and unreacted PTA powder without shutting down the system, a tapping mechanism 7 is installed on the outer wall of the vacuum line 5. Simultaneously, an ethylene glycol spraying mechanism 9 is installed at the bend in the upper part of the vacuum line 5 before entering the first-stage ethylene glycol vapor vacuum jet pump. When the adhered oligomers and unreacted PTA powder need to be removed, cleaning can be performed without shutting down the system. The wall of the vacuum pipeline 5 can be tapped by the tapping mechanism 7, causing vibration that detaches adhering oligomers and unreacted PTA powder from the inside of the pipeline, thus expanding the internal diameter. Simultaneously, the ethylene glycol spraying mechanism 9 provides high-pressure washing of the inner wall of the vacuum pipeline 5 from top to bottom, directly flushing away loosely adhered oligomers and unreacted PTA powder that have fallen into the pipeline after tapping, allowing them to be filtered out of the vacuum pipeline 5. This allows for online cleaning without disrupting normal production. The oligomers and solid substances adhering to the final polymerization vacuum line 5 are cleaned and discharged, ensuring that the inner wall of the final polymerization vacuum line 5 is clean and free of oligomers and solid substances. This ensures that the ethylene glycol vapor, water vapor and non-condensable gases in the polycondensation reactor can be normally extracted by the vacuum system 8. This effectively solves the problem that the ethylene glycol vapor, water vapor and non-condensable gases in the vacuum line 5 of the final polymerization reactor cannot be normally extracted by the vacuum system 8 due to the adhesion of more and more oligomers and solid substances. This ensures that the vacuum level of the polycondensation reactor can always meet the production needs, and the cleaning of the adhering substances inside the pipe wall is also convenient.

[0024] A further improvement is made to the striking mechanism 7, which includes a plurality of pneumatic striking hammers 72 disposed on the outer wall of the vacuum line 5 and a solenoid valve A71 for controlling the striking of the pneumatic striking hammers 72.

[0025] The striking mechanism 7 consists of multiple pneumatic hammers 72 installed on the outer wall of the vacuum pipeline 5 and a solenoid valve A71 for controlling the striking of the pneumatic hammers 72. At least two pneumatic hammers 72 are installed at both the upper and lower positions of the rising section of the vacuum pipeline 5, arranged in an alternating pattern. Installing the pneumatic hammers 72 at appropriate positions allows for better detachment of the vacuum pipeline 5 during the striking process. The installation of pneumatic hammers 72 at both the upper and lower positions of the vacuum pipeline 5 ensures sufficient vibration frequency throughout the entire pipeline. The compressed air source for the pneumatic hammers 72 is controlled by the solenoid valve A71, and the opening and closing action of the solenoid valve A71 is controlled by the time relay 10. This controls the pneumatic hammers 72 to simultaneously strike the upper and lower outer walls of the finalized polymerization vacuum pipeline 5 at a frequency of once every 3-5 seconds, dislodging the oligomers adhering to the inner wall of the finalized polymerization vacuum pipeline 5 through vibration. This makes operation more convenient and facilitates automated and precise control with other structures.

[0026] A further improvement is that a copper thickening layer 6 is provided on the outer wall of the vacuum pipeline 5 that is struck by the pneumatic hammer 72, so as to prevent damage to the outer wall of the vacuum pipeline 5 when the pneumatic hammer 72 strikes.

[0027] To prevent the pneumatic hammer 72 from damaging the outer wall of the vacuum line 5 during the hammering process, a copper thickening layer 6 is added to the outer wall of the vacuum line 5 that is being hammered by the pneumatic hammer 72. The copper thickening layer 6 can prevent the hammering from damaging the outer wall of the vacuum line 5.

[0028] A further improvement is made to the ethylene glycol spraying mechanism 9, which includes an ethylene glycol spraying pipe 93 located at a bend in the vacuum pipeline 5 near the first-stage vacuum system 8, a shower-shaped ethylene glycol spraying nozzle 91 located at one end of the ethylene glycol spraying pipe 93, a solenoid valve B94 and a flow regulating valve 92 located on the ethylene glycol pipeline.

[0029] The ethylene glycol spraying mechanism 9 consists of an ethylene glycol spraying pipe 93 installed on the vacuum pipeline 5 near the bend before the first-stage ethylene glycol vapor vacuum jet pump, a sprinkler-shaped ethylene glycol spray nozzle 91, a solenoid valve B94, and a flow regulating valve 92. The flow regulating valve 92 allows setting the ethylene glycol flow rate, thereby controlling the spray distance and intensity of the sprinkler-shaped ethylene glycol spray nozzle 91. By controlling the switching action of the time relay 10 and the solenoid valve B94, intermittent or continuous ethylene glycol spraying can be achieved, making operation more convenient and facilitating automated and precise control with other structures. Generally, after setting the ethylene glycol flow rate to 3000 kg / h, the opening is kept constant.

[0030] A further improvement is made in that both the ethylene glycol spraying mechanism 9 and the tapping mechanism 7 are equipped with a time relay 10, and the start-up time of the ethylene glycol spraying mechanism 9 and the tapping mechanism 7 is controlled by the time relay 10.

[0031] After the control line of the time relay 10 is connected to the remote controller 11, when production is required, the controller can start the automatic tapping and rinsing program in the control room through the remote controller 11 to realize automated operation. Each rinsing and tapping process lasts for 5 minutes. After one or more repeated operations, the inner wall of the final polymerization vacuum pipeline 5 is kept clean and free of oligomers to avoid blockage.

[0032] A further improvement is made whereby the ethylene glycol spray nozzle 91 is kept open to flush the pipe wall at an ethylene glycol flow rate of 2800 kg / h to 3500 kg / h, with each flushing process lasting 1 to 3 minutes; the ethylene glycol spray nozzle 91 is in the shape of a shower head; the duration of spraying the inner wall of the vacuum pipeline 5 with the ethylene glycol spray nozzle 91 is 5 to 10 seconds; during spraying, the opening is maintained at an ethylene glycol flow rate of 2800 kg / h to 3500 kg / h to flush the pipe wall, with each flushing process lasting 1 to 3 minutes.

[0033] Vacuum pipeline 5 has an inner diameter of about half a meter or even larger. Conventional structures cannot effectively clean the entire pipe wall. Therefore, the ethylene glycol spray nozzle 91 is designed like a shower head, allowing for 360-degree omnidirectional rinsing during the rinsing process. This enables the entire pipe to be cleaned even with a smaller spray diameter. The ethylene glycol spray nozzle 91 is a high-pressure water outlet structure. After spraying the inner wall of the final polymerized vacuum pipeline 5 for 5-10 seconds, an effective wetting effect is achieved on the entire section of the vacuum pipeline 5. During spraying, the opening is maintained at an ethylene glycol flow rate of 2800 kg / h to 3500 kg / h to rinse the pipe wall. Each rinsing process lasts 1-3 minutes to achieve sufficient high-pressure rinsing, preventing the loss of loosened oligomers and solid substances on the pipe wall.

[0034] A further improvement is made by first spraying the inner wall of the vacuum pipeline 5 with water by opening the ethylene glycol spray port 91 before the automatic knocking is performed, and then spraying is started again after the knocking is finished. During the knocking, the upper and lower outer walls of the vacuum pipeline 5 are knocked at a frequency of once every 3-5 seconds, and each knocking process lasts for 5-10 minutes.

[0035] Before the first tapping of the inner wall of vacuum pipeline 5, the inner wall of the final polymerization vacuum pipeline 5 is first sprayed with moisture by opening the ethylene glycol spray nozzle 91, followed by automatic tapping. After the tapping is completed, spraying is resumed. This process of spraying and wetting not only washes away easily detachable oligomers and solids, but also humidifies the surface oligomers and solids, causing them to adhere together. During the tapping process, the local vibration causes the detached oligomers and solids to detach in bulk, thus avoiding the problem of powdery detachment caused by the oligomers and solids being isolated. This results in better separation of oligomers and solids. During tapping, the upper and lower outer walls of the vacuum pipeline 5 are tapped simultaneously at a frequency of once every 3-5 seconds. Each tapping cycle lasts for 5-10 minutes, which better facilitates the detachment of oligomers and solids and prevents the inner layer of oligomers and solids from failing to detach effectively due to insufficient vibration.

[0036] A further improvement is that a spray circulation system 2 is connected between the final polymerization reactor 1 and the vacuum butterfly valve 12 via a pipeline. Some oligomers and unreacted PTA powder and other solid substances in the gas extracted by the vacuum system 8 are adsorbed by the spray circulation system 2 and then filtered out. The spray circulation system 2 includes a spray condenser 21 located between the final polymerization reactor 1 and the vacuum butterfly valve 12, an ethylene glycol liquid seal tank 24 connected to the spray condenser 21 via a pipeline, a circulation pump 23 located between the ethylene glycol liquid seal tank 24 and the spray condenser 21, and a filter 22. The spray condenser 21, the ethylene glycol liquid seal tank 24, the circulation pump 23, and the filter 22 are connected by pipelines to form an internal circulation pipeline.

[0037] The spray circulation system 2 consists of a spray condenser 21, an ethylene glycol liquid seal tank 24, a circulation pump 23, and a filter 22. The spray condenser 21, the ethylene glycol liquid seal tank 24, the circulation pump 23, and the filter 22 are connected by pipes to form an internal circulation pipeline. The spray condenser 21 is installed on the vacuum pipeline. The oligomers and unreacted PTA powder and other solid substances that fall off in the vacuum pipeline 5 can fall into the spray condenser 21 by their own weight, and then enter the ethylene glycol liquid seal tank 24 through the spray condenser 21. Finally, they are transported to the filter 22 by the circulation pump 23 for filtration. Through the circulating spray, some of the oligomers and unreacted PTA powder and other solid substances in the gas can be removed, and the oligomers and unreacted PTA powder and other solid substances cleaned from the vacuum pipeline 5 can be filtered and discharged, so that there is no need to stop the operation.

[0038] A further improvement is made in that two sets of spray circulation systems 2 are connected in series between the final polymerization reactor 1 and the vacuum butterfly valve 12. The two sets of spray circulation systems 2 are a primary spray circulation 3 and a secondary spray circulation 4, respectively. The secondary spray circulation 4 is arranged adjacent to the vacuum butterfly valve 12. The oligomers and solid substances removed by the tapping mechanism 7 and the ethylene glycol spraying mechanism 9 are filtered through the secondary spray circulation 4.

[0039] Two sets of spray circulation systems 2 are connected in series between the final polymerization reactor 1 and the vacuum butterfly valve 12. This can better ensure the cleanliness of the gas and prevent oligomers and unreacted PTA powder and other solids from entering the vacuum pipeline 5 and causing excessive adhesion. At the same time, the secondary spray circulation 4 is set adjacent to the vacuum butterfly valve 12. The oligomers and solids removed by the tapping mechanism 7 and the ethylene glycol spraying mechanism 9 are filtered through the secondary spray circulation 4, which can effectively prevent the detached oligomers and unreacted PTA powder and other solids from remaining in the pipeline.

[0040] Through the above structural improvements, during daily production, the final polymerization vacuum pipeline 5 can be periodically or at any time struck with a pneumatic hammer 72 and simultaneously flushed with ethylene glycol as needed. This flushes the oligomers and powder that fall off the inner wall of the vacuum pipeline 5 due to the striking into the ethylene glycol liquid seal tank 24, thus cleaning it out of the production system. This ensures that the inner wall of the final polymerization vacuum pipeline 5 is clean and free of oligomer accumulation, thereby ensuring that the ethylene glycol vapor, water vapor, and non-condensable gases in the polycondensation reactor can be normally extracted by the vacuum system 8, providing a stable vacuum environment for the polycondensation reaction and providing a strong guarantee for the stable production of polyester.

[0041] The device features a simple structure, ease of operation, and low cost; it can be operated remotely with a high degree of automation; the duration of each flushing and tapping process is adjustable, offering high flexibility; it can be operated online, allowing for adjustments to the operation frequency based on production conditions, making it convenient to use; the pneumatic tapping hammer 72 is located outside the vacuum pipeline 5, and different impact hammers 72 can be replaced as needed to adapt to different working conditions; the flushing glycol flow rate can be adjusted as needed, and the source of flushing glycol can also be changed to cope with different types of blockages; a thickened copper layer 6 is installed at the tapping point of the pneumatic tapping hammer 72 to protect the outer wall of the vacuum pipeline 5 from damage; the entire flushing and tapping process is automated, avoiding the risk of human error and preventing damage to the vacuum pipeline 5 due to improper tools or force during manual tapping, thus protecting equipment safety; this device has a compact structure, is easy to operate, and can also be applied to other similar pipeline devices.

[0042] The specific steps are as follows:

[0043] like Figure 1As shown: The final polymerization vacuum pipeline 5 is S-shaped, with one end connected to the spray condenser 21 of the secondary spray circulation 4 via a vacuum butterfly valve 12, and the other end connected to the ethylene glycol vapor vacuum jet pump, connecting the final polymerization reactor 1 and the vacuum system 8 together. The vacuum level of the final polymerization reactor 1 is controlled by the opening degree of the final polymerization vacuum butterfly valve 12. The implementation process is as follows: ① The flow rate of ethylene glycol entering the ethylene glycol spray pipe 93 is set to remain constant at around 3000 kg / h via the flow regulating valve 92. ② The switching frequency of the solenoid valve B94 is set to 5 seconds on and 2 seconds off via the time relay 10. ③ The switching frequency of the solenoid valve A71 is set to open once every 3 seconds via the time relay 10, thereby controlling the striking frequency of the pneumatic hammer 72 to once every 3 seconds. ④ After the solenoid valve B94 opens and the ethylene glycol flushing is completed for 5 seconds via the remote controller 11, the time relay 10 controls the solenoid valve A71 to start its switching action, and the pneumatic hammers 72A / B begin to automatically strike at a frequency of once every 3 seconds. ⑤ Production operators should monitor the vacuum level of the final polymerization reactor 1 and the residue level in the ethylene glycol liquid seal tank 24. ⑥ Five minutes after the first opening of solenoid valve B94, solenoid valve A71 will close and not open again, and the pneumatic hammer 72 will stop working, ending the rinsing process. At this time, solenoid valve B94 will reopen to control ethylene glycol rinsing for another 1-2 minutes, after which solenoid valve B94 will close to stop the ethylene glycol rinsing, completing one automatic rinsing cycle.

[0044] A further improvement is made by continuously and intermittently opening and closing the vacuum butterfly valve 12 during the flushing process to ensure that the liquid in the final polymerization vacuum pipeline 5 can flow downwards and will not block the channel.

[0045] When oligomers and solids are knocked down onto the upper side of vacuum butterfly valve 12, since the opening of vacuum butterfly valve 12 is not fully open, it will inevitably block some of the fallen oligomers and solids. Especially when the cleaning process begins when the opening reaches about 45%, a large amount of oligomers and solids will accumulate on the upper side of vacuum butterfly valve 12. At the same time, since the internal diameter of vacuum pipeline 5 increases after being knocked down, the internal vacuum level will become unbalanced. That is, if too much accumulates, the opening degree of vacuum butterfly valve 12 may actually decrease, resulting in an excessively high vacuum value in the final polymerization reactor 1, requiring the vacuum butterfly valve 12 to be opened further. If the opening degree is not affected after accumulation, it may easily lead to a vacuum imbalance in the final polymerization reactor 1. If the vacuum value is too small, the vacuum butterfly valve 12 needs to be reduced. In either case, incomplete cleaning will inevitably occur. Therefore, during the rinsing process, to ensure that the vacuum value of the final polymerization reactor 1 is within a controllable range, the vacuum butterfly valve 12 needs to be continuously and intermittently opened and closed. That is, the opening degree is repeatedly opened and closed to ensure that the liquid mixture being rinsed in the final polymerization vacuum pipeline 5 can flow downward quickly after the opening is large, without blocking the channel. The reduction is used to maintain the vacuum degree of the final polymerization reactor 1 to prevent the loss caused by the opening process. This ensures that the oligomers and solid substances adhering in the vacuum pipeline 5 will not accumulate near the vacuum butterfly valve 12 during the thorough cleaning process.

[0046] A further improvement is made to the vacuum butterfly valve 12, wherein the minimum opening degree is 10-15%, the maximum is 80-90%, and the opening and closing time is 5-10 seconds each time.

[0047] During the opening and closing of the vacuum butterfly valve 12, closing it too slightly can easily lead to an excessively high vacuum value in the final polymerization reactor 1, resulting in an uncontrolled melt viscosity. Conversely, opening it too much can easily lead to an excessively low vacuum value in the final polymerization reactor 1, resulting in an uncontrolled melt viscosity. Therefore, during the flushing process, the opening degree of the vacuum butterfly valve 12 is cyclically operated from 10-15% of the minimum value to 80-90% of the maximum value, with each opening and closing lasting 5-10 seconds. By controlling the opening degree, the vacuum value requirement of the final polymerization reactor 1 can be guaranteed, and the accumulation of substances on the inner wall of the pipeline can be thoroughly cleaned through continuous opening and closing.

[0048] The above embodiments are merely preferred embodiments of this application and should not be construed as limiting the scope of protection of this application. Any non-substantial changes and substitutions made by those skilled in the art based on this application shall fall within the scope of protection claimed by this application.

Claims

1. An online automatic flushing device for vacuum pipelines, comprising a final polymerization reactor (1), a vacuum butterfly valve (12), a vacuum pipeline (5), and a vacuum system (8) consisting of at least one set of ethylene glycol vapor vacuum jet pumps and ethylene glycol spray condensers, characterized in that: The vacuum pipeline (5) is provided with a knocking mechanism (7) on the outer wall, and a glycol spraying mechanism (9) is arranged in the vacuum pipeline (5); the oligomers and solid substances adhered to the inner wall of the vacuum pipeline (5) are loosened and dropped by the knocking mechanism (7), and the loosened or dropped oligomers and solid substances are washed by the glycol spraying mechanism (9) and then filtered and discharged along the vacuum pipeline (5).

2. The vacuum line online automatic flushing device according to claim 1, characterized in that: The knocking mechanism (7) comprises a plurality of pneumatic knocking hammers (72) arranged on the outer wall of the vacuum pipeline (5) and an electromagnetic valve A (71) for controlling the knocking of the pneumatic knocking hammers (72).

3. The vacuum line on-line automatic flushing device according to claim 2, characterized in that: The outer wall of the vacuum pipeline (5) subjected to the knocking of the pneumatic knocking hammers (72) is provided with a copper thickening layer (6) to prevent damage to the outer wall of the vacuum pipeline (5) caused by the knocking of the pneumatic knocking hammers (72).

4. The vacuum line online automatic flushing device according to claim 2, characterized in that: The glycol spraying mechanism (9) comprises a glycol spraying pipe (93) arranged on the vacuum pipeline (5) near a bending position of the vacuum system (8), a shower-shaped glycol spraying opening (91) arranged at one end of the glycol spraying pipe (93), an electromagnetic valve B (94) arranged on the glycol pipeline, and a flow regulating valve (92).

5. The vacuum line on-line automatic purging device according to claim 4, characterized in that: Both the glycol spraying mechanism (9) and the knocking mechanism (7) are provided with a time relay (10), and the starting time of the glycol spraying mechanism (9) and the knocking mechanism (7) is controlled by the time relay (10).

6. The vacuum line online automatic purging device according to claim 5, characterized in that: The glycol spraying opening (91) is kept open to flush the pipe wall with a glycol flow of 2800-3500 kg / h, and each flushing process lasts for 1-3 minutes.

7. The vacuum line online automatic purging device according to claim 6, characterized in that: The pneumatic knocking hammers (72) simultaneously knock the upper and lower outer walls of the vacuum pipeline (5) at a frequency of 3-5 times per second, and each knocking process lasts for 5-10 minutes.

8. The vacuum line online automatic purging device according to claim 4, characterized in that: A spraying circulation system (2) is connected by a pipeline between the final polymerization reactor (1) and the vacuum butterfly valve (12), and part of the oligomers and unreacted PTA powder and other solid substances in the gas drawn by the vacuum system (8) are adsorbed by the spraying circulation system (2) and then filtered and discharged.

9. The vacuum line online automatic purging device according to claim 8, characterized in that: Two groups of the spraying circulation system (2) are arranged in series between the final polymerization reactor (1) and the vacuum butterfly valve (12), and the two groups of the spraying circulation system (2) are respectively a primary spraying circulation (3) and a secondary spraying circulation (4); the secondary spraying circulation (4) is arranged adjacent to the vacuum butterfly valve (12), and the oligomers and solid substances removed by the knocking mechanism (7) and the glycol spraying mechanism (9) are filtered by the secondary spraying circulation (4).

10. The vacuum line online automatic purging device according to claim 9, characterized in that: The spray circulating system (2) comprises a spray condenser (21) arranged between the final polymerization reactor (1) and the vacuum butterfly valve (12), a glycol liquid seal groove (24) connected with the spray condenser (21) through a pipeline, a circulating pump (23) arranged between the glycol liquid seal groove (24) and the spray condenser (21), and a filter (22), and the spray condenser (21), the glycol liquid seal groove (24), the circulating pump (23) and the filter (22) are connected through pipelines to form an internal circulating pipeline.

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