Online automatic flushing method and device for final polymerization vacuum pipeline

Abstract

The invention discloses an online automatic flushing method for a final polymerization vacuum pipeline, which comprises the following steps of: knocking an ascending section part, connected with a final polymerization vacuum butterfly valve, of the final polymerization vacuum pipeline, so that substances attached to the inner wall of the final polymerization vacuum pipeline fall off through vibration; ethylene glycol is indirectly or continuously sprayed to the inner wall of the final polymerization vacuum pipeline through the ethylene glycol spraying opening, and substances which are knocked and vibrated off are flushed into an ethylene glycol liquid seal groove; filtering through an ethylene glycol filter, and judging whether the final polymerization vacuum pipeline is cleaned or not, so as to ensure that the inner wall of the final polymerization vacuum pipeline is clean and free of material attachment and accumulation. According to the invention, substances adhered in the final polymerization vacuum pipeline can be cleaned and discharged on line under the condition of not influencing normal production, and the inner wall of the final polymerization vacuum pipeline is ensured to be clean and free of substance accumulation, so that gas in a polycondensation reaction kettle can be ensured to be normally pumped out by a vacuum system, a stable vacuum environment is provided for the polycondensation reaction, and the production efficiency is improved. And a powerful guarantee is provided for stable polyester production.

Description

Technical Field

[0001] The present invention relates to the technical field of vacuum pipeline cleaning, and particularly relates to an online automatic flushing method and device for a final polymerization vacuum pipeline. Background Art

[0002] At present, in polyester production, the polycondensation reaction requires a stable vacuum environment, and the vacuum system is one of the important devices affecting the stability of polyester production. In the ContiTech polyester plant, the reaction kettle, ethylene glycol spray condenser and vacuum system are connected together through a vacuum butterfly valve and a vacuum pipeline. The opening degree of the vacuum butterfly valve is generally about 30-40. The smaller the opening degree, the smoother the vacuum pipeline. When the vacuum system extracts vapor-phase substances such as ethylene glycol steam and water vapor in the polycondensation reaction kettle, it will also entrain a part of solid substances such as oligomers and unreacted PTA powder. After being sprayed by the ethylene glycol spray condenser, part of them are carried away by ethylene glycol, and part of them enter the vacuum pipeline connecting the vacuum system. In addition, the vacuum degree before and after the vacuum butterfly valve changes greatly, and the higher vacuum degree behind the butterfly valve causes some oligomers dissolved in ethylene glycol to precipitate. These oligomers and solid substances adhere to the inner wall of the vacuum pipeline. With the long-term operation of the production device, the attachments on the inner wall of the vacuum pipeline accumulate, resulting in the reduction of the inner diameter of the vacuum pipeline or even being blocked, which causes the opening degree of the vacuum butterfly valve to become larger and larger. As a result, ethylene glycol steam, water vapor and non-condensable gas in the polycondensation reaction kettle cannot be normally extracted by the vacuum system, and the vacuum degree of the polycondensation reaction kettle cannot meet the production requirements, and it is necessary to stop the production for cleaning to resume, resulting in losses to the production. At the same time, due to the higher vacuum degree in the final polycondensation reaction kettle, it is easier to extract oligomers, so the final polymerization vacuum pipeline is more likely to be blocked. Therefore, an online automatic flushing method and device for the final polymerization vacuum pipeline are needed to solve the problem of blockage of the final polymerization vacuum pipeline during the production process. Summary of the Invention

[0003] In order to solve certain or some technical problems existing in the prior art, one of the purposes of the present application is to provide an online automatic flushing method for a final polymerization vacuum pipeline, which can clean and discharge oligomers and solid substances adhering to the inner wall of the final polymerization vacuum pipeline online without affecting normal production, ensure that the inner wall of the final polymerization vacuum pipeline is clean without accumulation of oligomers and solid substances, so as to ensure that ethylene glycol steam, water vapor and non-condensable gas in the polycondensation reaction kettle can be normally extracted by the vacuum system, and provide a stable vacuum environment for the progress of the polycondensation reaction, and provide a strong guarantee for the stability of polyester production.

[0004] Another purpose of the present application is to provide an online automatic flushing device for a final polymerization vacuum pipeline, which has a simple structure and is convenient to operate.

[0005] To solve the above-mentioned existing technical problems, one of the purposes of the present application is achieved by adopting the following technical solutions:

[0006] An online automatic flushing method for the final polymerization vacuum pipeline, the method comprising:

[0007] S1. Hammer at the rising section where the final polymerization vacuum pipeline is connected to the final polymerization vacuum butterfly valve to vibrate and shake off the oligomers and solid substances adhering to the inner wall of the final polymerization vacuum pipeline;

[0008] S2. Set an ethylene glycol spray port at the turning position before the final polymerization vacuum pipeline enters the first-stage ethylene glycol steam vacuum ejector, and spray the inner wall of the final polymerization vacuum pipeline indirectly or continuously through the ethylene glycol spray port; flush the oligomers and solid substances shaken off by the hammering with ethylene glycol into the ethylene glycol liquid seal tank;

[0009] S3. Filter the mixture in the ethylene glycol liquid seal tank through an ethylene glycol filter, and judge whether the final polymerization vacuum pipeline is cleaned, ensuring that the inner wall of the final polymerization vacuum pipeline is clean without oligomers and solid substances adhering and accumulating, and avoiding being blocked;

[0010] S4. The method for judging whether the final polymerization vacuum pipeline is cleaned includes:

[0011] Method 1. Judge the cleaning degree through the opening of the vacuum butterfly valve and the vacuum value of the final polymerization vacuum pipeline. When the opening is still too large, perform internal online cleaning of the final polymerization vacuum pipeline by repeating steps S1 and S2;

[0012] Method 2: Perform internal online cleaning of the final polymerization vacuum pipeline by repeating steps S1 and S2 at least once, and judge the wall cleanliness by the replacement frequency of the filter element of the ethylene glycol filter in step S3 after repeated cleaning until the filter element of the ethylene glycol filter reaches the normal replacement frequency.

[0013] Preferably, during the flushing process, the vacuum butterfly valve is continuously and intermittently opened and closed to ensure that the liquid in the final polymerization vacuum pipeline can flow downward and will not block the channel;

[0014] Preferably, the minimum opening degree of the vacuum butterfly valve is 10-15%, the maximum opening degree is 80-90%, and the opening and closing time for each time is 5-10 seconds.

[0015] Closing too small easily causes the vacuum value of the final polymerization reactor to be too large, resulting in out-of-control melt viscosity being too small. Opening too large easily causes the vacuum value of the final polymerization reactor to be too small, resulting in out-of-control melt viscosity being too large.

[0016] Preferably, before hammering in step S1, first spray the inner wall of the final polymerization vacuum pipeline wet through the ethylene glycol spray port, then perform automatic hammering, and start spraying again after the hammering ends.

[0017] Preferably, the duration of wetting the inner wall of the final polymerization vacuum pipeline by opening the ethylene glycol spray port is 5 to 10 seconds.

[0018] Preferably, the ethylene glycol spray port is in the shape of a shower head.

[0019] Preferably, the starting time of the knocking and spraying is controlled by a time relay.

[0020] Preferably, when knocking, the upper and lower outer walls of the final polymerization vacuum pipeline are knocked simultaneously at a frequency of once every 3 - 5 seconds, and each knocking process lasts for 5 to 10 minutes to end.

[0021] Preferably, when spraying, the opening is maintained to wash the tank wall with an ethylene glycol flow rate of 2800 kg / h to 3500 kg / h, and each washing process lasts for 1 to 3 minutes to end.

[0022] The second object of the present application is achieved by the following technical solution:

[0023] An on - line automatic flushing device for a final polymerization vacuum pipeline, comprising a final polymerization reactor, a vacuum butterfly valve, a vacuum pipeline, and a vacuum system composed of at least one group of ethylene glycol steam vacuum ejector pumps and ethylene glycol spray condensers. A spray circulation system is connected between the final polymerization reactor and the vacuum butterfly valve through a pipeline. Part of the solid substances such as oligomers and unreacted PTA powder in the gas extracted by the vacuum system are adsorbed by the spray circulation system and then filtered and discharged. A knocking mechanism is provided on the outer wall of the vacuum pipeline, and an ethylene glycol spray mechanism is provided at the turning point before the vacuum pipeline enters the first - stage ethylene glycol steam vacuum ejector pump. The oligomers and solid substances adhering to the inner wall of the vacuum pipeline are loosened and dropped by the knocking mechanism, and the loosened or dropped oligomers and solid substances are flushed by the high - pressure of the ethylene glycol spray mechanism and then flow back into the spray circulation system along the vacuum pipeline for filtration and discharge.

[0024] Preferably, the knocking mechanism includes a plurality of pneumatic knocking hammers provided on the outer wall of the vacuum pipeline and a solenoid valve A for controlling the knocking of the pneumatic knocking hammers.

[0025] Preferably, a copper - made thickened layer is provided on the outer wall of the vacuum pipeline that is knocked by the pneumatic knocking hammers to prevent damage to the outer wall of the vacuum pipeline when the pneumatic knocking hammers knock.

[0026] Preferably, the ethylene glycol spray mechanism includes an ethylene glycol spray pipe provided at the turning position before the vacuum pipeline enters the first - stage ethylene glycol steam vacuum ejector pump, a shower - shaped ethylene glycol spray port provided at one end of the ethylene glycol spray pipe, a solenoid valve B and a flow regulating valve provided on the ethylene glycol pipeline.

[0027] Preferably, the spray circulation system includes a spray condenser disposed between the final polymerization reactor and the vacuum butterfly valve, an ethylene glycol liquid seal tank connected to the spray condenser through a pipeline, a circulation pump disposed 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 through pipelines to form an internal circulation pipeline.

[0028] Preferably, two sets of the spray circulation systems are connected in series between the final polymerization reactor and the vacuum butterfly valve. The two sets of the spray circulation systems are respectively a primary spray circulation and a secondary spray circulation. The secondary spray circulation is disposed adjacent to the vacuum butterfly valve. The oligomers and solid substances removed by the knocking mechanism and the ethylene glycol spraying mechanism are filtered through the secondary spray circulation.

[0029] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0030] During the whole knocking and flushing process, the oligomers and solid substances adhering to the inner wall of the final polymerization vacuum pipeline can be cleaned and discharged online without affecting normal production, ensuring that the inner wall of the final polymerization vacuum pipeline is clean without accumulation of oligomers and solid substances. Thus, it is ensured that the ethylene glycol vapor, water vapor, and non-condensable gas in the polycondensation reactor can be normally extracted by the vacuum system, effectively solving the situation that the ethylene glycol vapor, water vapor, and non-condensable gas cannot be normally extracted by the vacuum system due to the increasing adhesion of more and more oligomers and solid substances in the vacuum pipeline of the final polycondensation reactor, enabling the vacuum degree of the polycondensation reactor to always meet the production requirements, and the cleaning of the adhesion on the pipe wall is also convenient. Through the combination of two judgment methods, it can not only realize the complete cleaning judgment of the oligomers and solid substances that can be cleaned on the vacuum pipe wall, but also achieve the purpose of ensuring the normal opening of the vacuum butterfly valve during online cleaning, with higher flexibility, providing a stable vacuum environment for the progress of the polycondensation reaction, and providing a strong guarantee for the stable production of polyester. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is a process flow schematic diagram of the present invention;

[0032] In the figure: 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, knocking mechanism; 71, solenoid valve A; 72, pneumatic hammer; 8, vacuum system; 9, ethylene glycol spraying mechanism; 91, shower-shaped ethylene glycol spray port; 92, flow regulating valve; 93, ethylene glycol spray pipe; 94, solenoid valve B; 10, relay; 11, remote controller; 12, vacuum butterfly valve. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0033] Next, in combination with the accompanying drawings and specific embodiments, the present application will be further described. It should be noted that, on the premise of no conflict, the following-described embodiments or technical features can be arbitrarily combined to form new embodiments.

[0034] In the description of the present application, it should be understood that the orientation or positional relationship indicated by terms such as "upper", "lower", "left", "right", etc. is based on the orientation or positional relationship shown in the accompanying drawings. It is only for the convenience of describing the present application 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 should not be construed as a limitation to the present application.

[0035] The terms "first", "second", etc. in the present application are used to distinguish similar objects, rather than to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so that the embodiments of the present application can be implemented in an order other than those illustrated or described herein, and the objects distinguished by "first", "second", etc. are usually of the same category, and the number of objects is not limited. For example, the first object can be one or multiple. In addition, "and / or" in the specification and claims means at least one of the connected objects, and the character " / ", generally represents an "or" relationship between the associated objects before and after.

[0036] Embodiment 1:

[0037] As Figure 1 shown, an on-line automatic flushing method for a final polymerization vacuum pipeline, the method comprising:

[0038] S1. Knock at the rising section where the final polymerization vacuum pipeline 5 is connected to the final polymerization vacuum butterfly valve 12 to vibrate and shake off the oligomers and solid substances adhering to the inner wall of the final polymerization vacuum pipeline 5;

[0039] S2. Provide an ethylene glycol spray port 91 at the turning position before the final polymerization vacuum pipeline 5 enters the first-stage ethylene glycol steam vacuum ejector, and perform intermittent or continuous spraying of ethylene glycol on the inner wall of the final polymerization vacuum pipeline 5 through the ethylene glycol spray port 91; flush the oligomers and solid substances shaken off by knocking with ethylene glycol into the ethylene glycol liquid seal tank 24;

[0040] S3. Filter the mixture in the ethylene glycol liquid seal tank 24 through the ethylene glycol filter 22, and determine whether the final polymerization vacuum pipeline 5 is cleaned, ensuring that the inner wall of the final polymerization vacuum pipeline 5 is clean without oligomers and solid substances adhering and accumulating, and avoiding blockage;

[0041] S4. The method for determining whether the final polymerization vacuum pipeline 5 is cleaned includes:

[0042] Method 1: Judge the cleaning degree by the opening degree of the vacuum butterfly valve 12 and the vacuum value of the final polymerization vacuum pipeline 5. When the opening degree is still too large, realize the internal online cleaning of the final polymerization vacuum pipeline 5 by repeating steps S1 and S2;

[0043] Method 2: Realize the internal online cleaning of the final polymerization vacuum pipeline 5 by repeating the above steps S1 and S2 at least once. Judge the wall cleanliness by the filter element replacement frequency of the ethylene glycol filter 22 in step S3 after repeated cleaning until the filter element of the ethylene glycol filter 22 reaches the normal replacement frequency.

[0044] In the production of polyester, when the vacuum pipeline 5 is unobstructed, the opening degree of the vacuum butterfly valve 12 is generally around 35. However, over time, due to the relatively high vacuum degree in the final polycondensation reactor, it is easier to extract oligomers and solid substances. Therefore, the final polymerization vacuum pipeline 5 is more likely to adhere to an increasing amount of oligomers and solid substances, resulting in a smaller inner diameter of the vacuum pipeline 5. Consequently, the opening degree of the vacuum butterfly valve 12 becomes larger and larger. In the past, until the opening degree reached 60%, the vacuum regulation ability would be greatly reduced. If it continued to develop, it would lead to the inability of the ethylene glycol steam, water vapor, and non-condensable gas in the polycondensation reactor to be normally extracted by the vacuum system 8, and the vacuum degree of the polycondensation reactor could not meet the production requirements, and it was necessary to stop the machine for cleaning to resume, causing losses to production. Therefore, in order to solve the technical problem of needing to stop the machine to clean the adherents, a set of online automatic flushing method for the final polymerization vacuum pipeline 5 is designed. First, when the opening degree of the vacuum valve is greater than a certain value or after a certain period of time, for example, when the opening degree of the vacuum butterfly valve 12 reaches 45% or the continuous working time reaches 3 months, intermittent continuous knocking is carried out at various parts of the rising section vacuum pipeline 5 where the final polymerization vacuum pipeline 5 is connected to the final polymerization vacuum butterfly valve 12 for a period of time, so that the oligomers and solid substances adhering to the inner wall of the final polymerization vacuum pipeline 5 vibrate and fall into the vacuum pipeline through vibration, significantly increasing the inner diameter of the vacuum pipeline. At this time, part of it directly falls into the ethylene glycol liquid seal tank 24 from the opening direction of the vacuum butterfly valve 12, while part is blocked by the vacuum butterfly valve 12. Then, an ethylene glycol spray port 91 is set at the turning position before the final polymerization vacuum pipeline 5 enters the first-stage ethylene glycol steam vacuum ejector, and the inner wall of the final polymerization vacuum pipeline 5 is sprayed and flushed indirectly or continuously with ethylene glycol through the ethylene glycol spray port 91. While the loosened oligomers and solid substances on the pipe wall fall off, the oligomers and solid substances accumulated on the pipe wall are flushed into the ethylene glycol liquid seal tank 24 along the opening of the vacuum butterfly valve 12, thus completing the automatic cleaning of the adhered oligomers and solid substances. The oligomers and ethylene glycol mixture located in the ethylene glycol liquid seal tank 24 are filtered out by the ethylene glycol filter 22. During the entire knocking and flushing process, cleaning can be achieved under the normal operation of the vacuum pipeline, effectively solving the situation that the ethylene glycol steam, water vapor, and non-condensable gas in the final polycondensation reactor cannot be normally extracted by the vacuum system 8 due to the adhesion of an increasing amount of oligomers and solid substances to the vacuum pipeline 5, enabling the vacuum degree of the polycondensation reactor to always meet the production requirements and facilitating the cleaning of the adherents on the pipe wall.After a primary cleaning, the operator can judge whether secondary dredging is needed according to different situations, and judge whether the end polymerization vacuum pipeline 5 is cleaned by the data of the production equipment, so as to ensure that the inner wall of the end polymerization vacuum pipeline 5 is clean without oligomers and solid substances adhering and accumulating. Among them, the methods for judging whether the end polymerization vacuum pipeline 5 is cleaned are mainly divided into two types: First, judge by the opening degree of the vacuum butterfly valve 12 and the vacuum value of the end polymerization vacuum pipeline 5. For example, when the opening degree of the vacuum butterfly valve 12 shrinks from 45% before cleaning to 40%, and the vacuum value of the end polymerization reactor 1 still shows too large, it means that it is not cleaned and needs to be knocked and rinsed again. After multiple knocks and rinses until the pressure value reaches the requirement when the opening degree reaches about 35%, it means that the cleaning is completed; Second, on the basis of the first type, at least repeat steps S1 and S2 once to realize the online cleaning of the inside of the end polymerization vacuum pipeline 5. The mixture washed down will enter the ethylene glycol liquid seal tank 24 and be filtered by the ethylene glycol filter 22. When the ethylene glycol filter 22 in the ethylene glycol liquid seal tank 24 often needs to replace the cleaning filter element after each cleaning, it means that it is not yet clean. Until the frequency of filter element replacement is close to the normal state frequency after the liquid washed down for the last time is filtered, it means that the oligomers and solid substances that can be cleaned on the inner wall of the vacuum pipeline 5 have been completely cleaned. Through the combination of the two methods, it is possible to realize the complete cleaning judgment of the oligomers and solid substances that can be cleaned on the vacuum pipe wall, and at the same time, the purpose of ensuring the normal operation of the vacuum butterfly valve 12 under normal opening degree can be achieved, with higher flexibility.

[0045] Furthermore, it is improved that during the rinsing process, the vacuum butterfly valve 12 is continuously and intermittently opened and closed to ensure that the liquid in the end polymerization vacuum pipeline 5 can flow downward and will not block the channel.

[0046] When the oligomers and solid substances are knocked off and fall onto the upper side of the vacuum butterfly valve 12, since the opening degree of the vacuum butterfly valve 12 is not fully open, it will inevitably block some of the fallen oligomers and solid substances. Especially during the cleaning process when the opening degree reaches about 45%, a large amount of oligomers and solid substances will accumulate on the upper side of the vacuum butterfly valve 12. At the same time, because the internal diameter of the vacuum pipeline 5 becomes larger after knocking, at this time, the internal vacuum degree will be unbalanced. That is, if the accumulation is too much, it is easy to cause the opening and closing degree of the vacuum butterfly valve 12 to become smaller instead, resulting in an excessive vacuum value in the final polymerization reactor 1, and the vacuum butterfly valve 12 needs to be opened further; if the opening degree is not affected after accumulation, it is easy to cause the vacuum value in the final polymerization reactor 1 to be too small, and the vacuum butterfly valve 12 needs to be closed. In either case, it will inevitably lead to the situation that the cleaning is not clean. Therefore, during the flushing 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 operated to open and close, so as to ensure that the flushing liquid mixture in the final polymerization vacuum pipeline 5 can flow downward quickly after opening and will not block the channel, and after closing, it is used to maintain the loss of the vacuum degree in the final polymerization reactor 1 during the opening process, so that the oligomers and solid substances adhered to the inner wall of the vacuum pipeline 5 will not accumulate near the vacuum butterfly valve 12 during the thorough cleaning process.

[0047] Further improvement is that the minimum opening and closing degree of the vacuum butterfly valve 12 is 10 - 15%, the maximum is 80 - 90%, and the opening and closing time each time is 5 - 10 seconds.

[0048] During the opening and closing process of the vacuum butterfly valve 12, if it is closed too small, it is easy to cause an excessive vacuum value in the final polymerization reactor 1, resulting in out-of-control of the melt viscosity being too small, and if it is opened too large, it is easy to cause an excessive vacuum value in the final polymerization reactor 1, resulting in out-of-control of the melt viscosity being too large. Therefore, during the flushing process, the opening and closing degree of the vacuum butterfly valve 12 is cycled between closing and the minimum of 10 - 15% to the maximum of 80 - 90%, and the opening and closing time each time is 5 - 10 seconds. By controlling the opening and closing degree, it can not only meet the requirement of the vacuum value of the final polymerization reactor 1, but also achieve the thorough cleaning of the deposits on the inner wall of the pipeline through continuous opening and closing.

[0049] Further improvement is that before the knocking in step S1, first wet the inner wall of the final polymerization vacuum pipeline 5 by opening the ethylene glycol spray port 91, then perform automatic knocking, and start spraying again after the knocking ends; when knocking, knock on the upper and lower outer walls of the final polymerization vacuum pipeline 5 at a frequency of 3 - 5 seconds each time, and each knocking process lasts for 5 - 10 minutes to end.

[0050] Before the first knocking on the inner wall of the vacuum pipeline 5, first wet the inner wall of the final polymerization vacuum pipeline 5 by opening the ethylene glycol spray nozzle 91, and then perform automatic knocking. After the knocking is completed, start spraying again. This can not only wash and clean the oligomers and solid substances that are easy to fall off through the wetting step, but also humidify and bond the oligomers and solid substances on the surface into a whole, so that during the knocking process, the oligomers and solid substances that fall off through local vibration can drive the surrounding oligomers and solid substances to fall off as a whole, thus avoiding the problem that the oligomers and solid substances form powdery detachment during the knocking process due to being independent of each other, and having a better separation effect on the oligomers and solid substances. When knocking, knock on the upper and lower outer walls of the final polymerization vacuum pipeline 5 at a frequency of once every 3 - 5 seconds, and each knocking process lasts for 5 - 10 minutes to end, which can better achieve the detachment of the oligomers and solid substances and avoid the situation that the inner-layer oligomers and solid substances cannot effectively fall off due to insufficient vibration force.

[0051] Furthermore, it is further improved that the ethylene glycol spray nozzle 91 is in the shape of a shower head; the duration of wetting the inner wall of the final polymerization vacuum pipeline 5 by opening the ethylene glycol spray nozzle 91 is 5 - 10 seconds; when spraying, keep the opening degree and wash the tank wall with an ethylene glycol flow rate of 2800 kg / h - 3500 kg / h, and each washing process lasts for 1 - 3 minutes to end.

[0052] The inner diameter of the vacuum pipeline 5 can reach about half a meter or even larger. Conventional structures are difficult to achieve the flushing and cleaning of the entire pipe wall. Therefore, the ethylene glycol spray nozzle 91 in the shape of a shower head can achieve 360-degree all-round flushing during the flushing process, and can achieve the flushing and cleaning of the entire pipeline interior with a smaller spraying diameter; and the opened ethylene glycol spray nozzle 91 is a high-pressure water outlet structure. After spraying the inner wall of the final polymerization vacuum pipeline 5 for 5 - 10 seconds, an effective wetting effect of the entire section of the vacuum pipeline 5 can be achieved. When spraying, keep the opening degree and wash the tank wall with an ethylene glycol flow rate of 2800 kg / h - 3500 kg / h, and each washing process lasts for 1 - 3 minutes to end, which can achieve a sufficient high-pressure flushing effect and avoid the situation that the oligomers and solid substances on the pipe wall cannot be washed off after being loosened.

[0053] Even further, it is improved that the starting timing of the knocking and spraying is controlled by a time relay 10.

[0054] Through the time relay 10, remote automatic control can be realized, thus realizing automated operation. During the cleaning process of the entire vacuum pipe wall, manual operation is no longer required, and the labor intensity is lower.

[0055] Example 2:

[0056] As shown Figure 1 in the figure, an on-line automatic flushing device for the final polymerization vacuum pipeline 5 includes a final polymerization reactor 1, a vacuum butterfly valve 12, a vacuum pipeline 5, and a vacuum system 8 composed of at least one group of ethylene glycol steam vacuum ejector pumps and ethylene glycol spray condensers 21. A spray circulation system 2 is connected between the final polymerization reactor 1 and the vacuum butterfly valve 12 through a pipeline. Part of the oligomers and solid substances such as unreacted PTA powder in the gas extracted by the vacuum system 8 are adsorbed by the spray circulation system 2 and then filtered and discharged. A knocking mechanism 7 is provided on the outer wall of the vacuum pipeline 5, and an ethylene glycol spraying mechanism 9 is provided at the turning point before the vacuum pipeline 5 enters the first-stage ethylene glycol steam vacuum ejector pump. The oligomers and solid substances adhering 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 high pressure of the ethylene glycol spraying mechanism 9 and then flow back into the spray circulation system 2 along the vacuum pipeline 5 for filtration and discharge.

[0057] During the actual production process, the general vacuum system 8 is generally composed of four groups of ethylene glycol vapor vacuum ejector pumps and an ethylene glycol spray condenser 21. The vacuum pipeline 5 is arranged in an S shape or a Z shape and slopes upward. The vacuum degree in the final polymerization reactor 1 is evacuated through the vacuum system 8 composed of the ethylene glycol vapor vacuum ejector pumps and the ethylene glycol spray condenser 21. Among them, the vacuum value is controlled by a vacuum butterfly valve 12. Although some solid substances such as partial oligomers and unreacted PTA powder in the gas before entering the vacuum pipeline 5 can be sprayed out through the spray circulation system 2, still, a part of them will enter the vacuum pipeline 5, resulting in adhesion to the pipe wall. As time goes by, the thickness of the adhesion will become larger and larger. Therefore, in order to facilitate the cleaning of these adhered oligomers and unreacted PTA powder and other solid substances without stopping the machine, a knocking mechanism 7 is installed on the outer wall of the vacuum pipeline 5. At the same time, an ethylene glycol spray mechanism 9 is installed at the bend before the upper end of the vacuum pipeline 5 enters the first-stage ethylene glycol vapor vacuum ejector pump. When the adhered oligomers and unreacted PTA powder and other solid substances need to be cleaned, without stopping the machine, the pipe wall of the vacuum pipeline 5 can be knocked by the knocking mechanism 7. After the pipe wall forms vibration, the adhered oligomers and unreacted PTA powder and other solid substances will fall off from the inside of the pipe wall, thereby expanding the internal diameter. At the same time, the ethylene glycol spray mechanism 9 can carry out high-pressure flushing on the inner wall of the vacuum pipeline 5 that can be sprayed from top to bottom, so that some of the oligomers and unreacted PTA powder and other solid substances that are not firmly adhered and fall into the pipe wall after knocking are directly flushed and then enter the spray circulation system 2 for filtration, so as to realize the on-line cleaning and discharge of the oligomers and solid substances adhered in the final polymerization vacuum pipeline 5 without affecting normal production, ensure that the inner wall of the final polymerization vacuum pipeline 5 is clean without accumulation of oligomers and solid substances, so as to ensure that the ethylene glycol vapor, water vapor and non-condensable gas in the polycondensation reactor can be normally extracted by the vacuum system 8, effectively solve the situation that the ethylene glycol vapor, water vapor and non-condensable gas in the vacuum pipeline 5 of the final polycondensation reactor cannot be normally extracted due to the increasing adhesion of oligomers and solid substances, make the vacuum degree of the polycondensation reactor always meet the production requirements, and it is also convenient to clean the adhesion inside the pipe wall.

[0058] Further improved, the knocking mechanism 7 includes a plurality of pneumatic knocking hammers 72 arranged on the outer wall of the vacuum pipeline 5 and a solenoid valve A71 for controlling the knocking of the pneumatic knocking hammers 72.

[0059] The knocking mechanism 7 is composed of a plurality of pneumatic hammers 72 installed on the outer wall of the vacuum pipeline 5 and a solenoid valve A71 for controlling the knocking of the pneumatic hammers 72. Among them, pneumatic hammers 72 are installed at both the upper and lower positions of the rising section of the vacuum pipeline 5. At least two of them are arranged staggeredly. After installing the pneumatic hammers 72 at appropriate positions, during the knocking process, the vacuum pipeline 5 can be better detached. And by installing pneumatic hammers 72 at both the upper and lower positions of the vacuum pipeline 5, it can ensure that the entire vacuum pipeline 5 generates a sufficient vibration frequency. The compressed air sources of the pneumatic hammers 72 are jointly controlled by the solenoid valve A71. The opening and closing action of the solenoid valve A71 is controlled by a time relay 10, so as to control the pneumatic hammers 72 to knock on the upper and lower outer walls of the final polymerization vacuum pipeline 5 at a frequency of once every 3 - 5 seconds, and vibrate and shake off the oligomers adhering to the inner wall of the final polymerization vacuum pipeline 5. The operation is more convenient and it is more convenient to achieve automatic precise regulation with other structures.

[0060] Furthermore, it is further improved that a copper - made thickened layer 6 is provided on the outer wall of the vacuum pipeline 5 that is knocked by the pneumatic hammer 72, and the copper - made thickened layer 6 is used to prevent damage to the outer wall of the vacuum pipeline 5 when the pneumatic hammer 72 knocks.

[0061] In order to avoid damage to the outer wall of the vacuum pipeline 5 caused by the pneumatic hammer 72 during the knocking process, a part of the copper - made thickened layer 6 is added to the outer wall of the vacuum pipeline 5 that is knocked by the pneumatic hammer 72. The copper - made thickened layer 6 can prevent damage to the outer wall of the vacuum pipeline 5 caused by knocking.

[0062] Furthermore, it is further improved that the ethylene glycol spraying mechanism 9 includes an ethylene glycol spray pipe 93 arranged at the turning position of the vacuum pipeline 5 near the first - stage ethylene glycol steam vacuum ejector, a flower - shaped ethylene glycol spray port 91 arranged at one end of the ethylene glycol spray pipe 93, a solenoid valve B94 arranged on the ethylene glycol pipeline, and a flow regulating valve 92.

[0063] The ethylene glycol spraying mechanism 9 is composed of an ethylene glycol spray pipe 93, a flower - shaped ethylene glycol spray port 91, a solenoid valve B94, and a flow regulating valve 92 installed at the turning position of the vacuum pipeline 5 near the first - stage ethylene glycol steam vacuum ejector. The flow regulating valve 92 can set the passing amount of ethylene glycol, so as to control the spraying distance and intensity of the flower - shaped ethylene glycol spray port 91. By controlling the opening and closing actions of the time relay 10 and the solenoid valve B94, the intermittent or continuous spraying of ethylene glycol can be realized. The operation is more convenient and it is more convenient to achieve automatic precise regulation with other structures. Generally, after setting the flow of ethylene glycol to 3000 kg / h, the opening remains unchanged.

[0064] A time relay 10 is provided on each of the ethylene glycol spraying mechanism 9 and the knocking mechanism 7. The start times of the ethylene glycol spraying mechanism 9 and the knocking mechanism 7 are controlled by the time relay 10. After the control circuit of the time relay 10 is connected to the remote controller 11, when production is required, the operator can start the automatic knocking and flushing procedures through the remote controller 11 in the control room, thus realizing automatic operation. Among them, each flushing and knocking process lasts for 5 minutes. After one or multiple repeated operations, it is ensured that the inner wall of the end polymerization vacuum pipeline 5 is clean without the attachment and accumulation of oligomers, avoiding blockage.

[0065] Further improved, the spraying circulation system 2 includes a spraying condenser 21 provided between the end polymerization reactor 1 and the vacuum butterfly valve 12, an ethylene glycol liquid seal tank 24 connected to the spraying condenser 21 through a pipeline, a circulation pump 23 provided between the ethylene glycol liquid seal tank 24 and the spraying condenser 21, and a filter 22. The spraying 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.

[0066] The spraying circulation system 2 is composed of a spraying condenser 21, an ethylene glycol liquid seal tank 24, a circulation pump 23, and a filter 22. The spraying 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. The spraying condenser 21 is installed on the vacuum pipeline. The oligomers and solid substances such as unreacted PTA powder that fall off in the vacuum pipeline 5 can fall into the spraying condenser 21 by their own weight, then enter the ethylene glycol liquid seal tank 24 through the spraying condenser 21, and finally be transported to the filter 22 by the circulation pump 23 for filtration. Through circulating spraying, it can not only remove some oligomers and solid substances such as unreacted PTA powder in the gas, but also filter and discharge the oligomers and solid substances such as unreacted PTA powder cleaned from the vacuum pipeline 5, so that shutdown operation is not required.

[0067] Even further improved, two sets of the spraying circulation systems 2 are connected in series between the end polymerization reactor 1 and the vacuum butterfly valve 12. The two sets of the spraying circulation systems 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. The oligomers and solid substances removed by the knocking mechanism 7 and the ethylene glycol spraying mechanism 9 are filtered by the secondary spraying circulation 4.

[0068] Two sets of the spray circulation systems 2 are connected in series between the final polymerization reactor 1 and the vacuum butterfly valve 12, which can better ensure the cleanliness of the gas and avoid the problem of too fast adhesion caused by solid substances such as oligomers and unreacted PTA powder entering the vacuum pipeline 5. At the same time, the secondary spray 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 ethylene glycol spray mechanism 9 are filtered through the secondary spray circulation 4, which can effectively avoid the retention of solid substances such as shed oligomers and unreacted PTA powder in the pipeline.

[0069] Through the improvement of the above structure, during the daily production process, the final polymerization vacuum pipeline 5 can be knocked regularly or at any time according to production needs with a pneumatic hammer 72 and flushed with ethylene glycol at the same time. The oligomers and powder falling off the inner wall of the vacuum pipeline 5 due to knocking are flushed into the ethylene glycol liquid seal tank 24 and then cleaned out of the production system, ensuring that the inner wall of the final polymerization vacuum pipeline 5 is clean without oligomer accumulation, so as to ensure that the ethylene glycol vapor, water vapor and non-condensable gas in the polycondensation reactor can be normally extracted by the vacuum system 8, providing a stable vacuum environment for the progress of the polycondensation reaction and providing a strong guarantee for the stable polyester production.

[0070] The structure is relatively simple, easy to operate and has a low cost; it can be remotely operated with a high degree of automation; the duration of each flushing and knocking process can be adjusted with high flexibility; it can be operated online and the operation frequency can be adjusted according to the production situation, which is convenient to use; the pneumatic hammer 72 is arranged outside the vacuum pipeline 5, and pneumatic hammers 72 with different impact forces can be replaced according to needs to adapt to different working conditions; the flow rate of the flushing ethylene glycol can be adjusted according to needs, and the source of the flushing ethylene glycol can also be replaced according to needs to cope with blockages in different situations; a copper thickened layer 6 is arranged at the knocking position of the pneumatic hammer 72 to protect the outer wall of the vacuum pipeline 5 from being damaged by knocking; the whole flushing and knocking process is automatic, which can avoid the hidden danger of misoperation in manual operation and also avoid the damage to the vacuum pipeline 5 caused by improper knocking tools or force during manual knocking, protecting the safety of the equipment; the device has a compact structure and simple operation and can also be applied to other similar pipeline devices.

[0071] The specific operation is as follows:

[0072] Such as Figure 1As shown in the figure: The final polymerization vacuum pipeline 5 is in an S shape. One end is connected to the spray condenser 21 of the secondary spray circulation 4 through the vacuum butterfly valve 12, and the other end is connected to the ethylene glycol steam vacuum ejector pump, connecting the final polymerization reactor 1 and the vacuum system 8 together. The vacuum degree 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 Set the ethylene glycol flow rate entering the ethylene glycol spray pipe 93 to be about 3000 kg / h and keep it unchanged through the flow regulating valve 92. ② Set the switching frequency of the solenoid valve B94 to be on for 5 seconds and off for 2 seconds through the time relay 10. ③ Set the switching frequency of the solenoid valve A71 to open once every 3 seconds through the time relay 10, so as to control the knocking frequency of the pneumatic hammer 72 to be once every 3 seconds. ④ After setting the solenoid valve B94 to open for ethylene glycol flushing for 5 seconds through the remote controller 11, the time relay 10 controls the solenoid valve A71 to start the switching action, and the pneumatic hammers 72A / B start to automatically knock at a frequency of once every 3 seconds. ⑤ The production operator pays attention to the vacuum degree of the final polymerization reactor 1 and the residue situation in the ethylene glycol liquid seal tank 24. ⑥ Five minutes after starting the timing from the first opening of the solenoid valve B94, the solenoid valve A71 is closed and no longer opened, and the pneumatic hammer 72 stops working and the knocking ends. At this time, the solenoid valve B94 is opened again to control the ethylene glycol to continue flushing for 1 - 2 minutes, and then the solenoid valve B94 is closed to stop the ethylene glycol flushing, and an automatic knocking and flushing ends.

[0073] The above-mentioned implementation manner is only the preferred implementation manner of the present application, and cannot be used to limit the protection scope of the present application. Any non-substantial changes and substitutions made by those skilled in the art based on the present application belong to the protection scope required by the present application.

Claims

1. A method for online automatic flushing of a final polymerization vacuum pipeline, characterized in that: The method comprises: S1, tapping the ascending section where the final vacuum pipeline (5) is connected to the final vacuum butterfly valve (12), so that the oligomers and solid substances attached to the inner wall of the final vacuum pipeline (5) are shaken off by vibration; S2, setting an ethylene glycol spray port at the turning position before the final polymerization vacuum pipeline (5) enters the first-stage ethylene glycol steam vacuum jet pump, and spraying ethylene glycol indirectly or continuously on the inner wall of the final polymerization vacuum pipeline (5) through the ethylene glycol spray port; flushing the knocked-off oligomers and solid substances into the ethylene glycol liquid sealing tank (24) through the ethylene glycol; S3, the mixture in the ethylene glycol liquid seal tank (24) is filtered out through the ethylene glycol filter (22), and it is determined whether the final polymerization vacuum pipeline (5) is cleaned, so as to ensure that the inner wall of the final polymerization vacuum pipeline (5) is clean without oligomers and solid substances attached and accumulated, and avoid being blocked; S4, a method for judging whether the final polymerization vacuum pipeline (5) is clean comprises: Method 1: judging the cleaning degree by the opening of the vacuum butterfly valve (12) and the vacuum value of the final vacuum pipeline (5); when the opening is still too large, online cleaning of the interior of the final vacuum pipeline (5) is achieved by repeating steps S1 and S2; Method 2: The internal part of the final polymerization vacuum pipeline (5) is cleaned online by repeating steps S1 and S2 at least once, and the cleanliness of the pipe wall is judged by the replacement frequency of the filter element of the ethylene glycol filter (22) in step S3 after repeated cleaning, until the filter element of the ethylene glycol filter (22) reaches the normal replacement frequency.

2. A method for online automatic flushing of a final polymerization vacuum pipeline according to claim 1, characterized in that: During the flushing process, the vacuum butterfly valve (12) is continuously opened and closed intermittently to ensure that the liquid in the final vacuum pipeline (5) can flow downward.

3. The method for online automatic flushing of a final polymerization vacuum pipeline according to claim 1, characterized in that: Before the tapping in step S1, the inner wall of the final polymerization vacuum pipeline (5) is first wetted by opening the ethylene glycol spray port, and then the automatic tapping is performed. After the tapping is completed, the spraying is started again.

4. The method for online automatic flushing of a final polymerization vacuum pipeline according to claim 1, characterized in that: The start timing of the knocking and spraying is controlled by a time relay (10).

5. A method for online automatic flushing of a final polymerization vacuum pipeline according to claim 4, characterized in that: When the knocking is performed, the upper and lower outer walls of the final polymerization vacuum pipeline (5) are knocked at the same time at a frequency of once every 3 to 5 seconds, and each knocking process lasts for 5 to 10 minutes.

6. A device for online automatic flushing of a final polymerization vacuum pipeline by the online automatic flushing method of a final polymerization vacuum pipeline as claimed in any one of claims 1 to 5, 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 group of ethylene glycol steam vacuum jet pumps and ethylene glycol spray condensers, wherein a spray circulation system (2) is connected between the final polymerization reactor (1) and the vacuum butterfly valve (12) through a pipeline, and part of the 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 and discharged, characterized in that: A knocking mechanism (7) is provided on the outer wall of the vacuum pipeline (5), and an ethylene glycol spraying mechanism (9) is provided at the turning point before the vacuum pipeline (5) enters the first-stage ethylene glycol steam vacuum jet pump. The oligomers and solid substances adhering to the inner wall of the vacuum pipeline (5) are loosened and dropped by the knocking mechanism (7). The loosened or dropped oligomers and solid substances are washed under high pressure by the ethylene glycol spraying mechanism (9) and then flow back along the vacuum pipeline (5) into the spraying circulation system (2) for filtration and discharge.

7. The online automatic flushing device for the final polymerization vacuum pipeline according to claim 6 is 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 a solenoid valve A (71) for controlling the knocking of the pneumatic knocking hammers (72).

8. The online automatic flushing device for the final polymerization vacuum pipeline according to claim 7 is characterized in that: A copper thickening layer (6) is provided on the outer wall of the vacuum pipeline (5) struck by the pneumatic striking hammer (72), and the copper thickening layer (6) prevents the pneumatic striking hammer (72) from causing damage to the outer wall of the vacuum pipeline (5) when striking.

9. The online automatic flushing device for the final polymerization vacuum pipeline according to claim 6 is characterized in that: The ethylene glycol spraying mechanism (9) comprises an ethylene glycol spraying pipe (93) arranged on the vacuum pipeline (5) at a turning position before the first-stage ethylene glycol steam vacuum jet pump, a shower-shaped ethylene glycol spraying port (91) arranged at one end of the ethylene glycol spraying pipe (93), an electromagnetic valve B (94) and a flow regulating valve (92) arranged on the ethylene glycol pipeline.

10. The online automatic flushing device for the final polymerization vacuum pipeline according to claim 9, characterized in that: The spray circulation system (2) comprises a spray condenser (21) arranged 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) and a filter (22) arranged between the ethylene glycol liquid seal tank (24) and the spray condenser (21); the spray condenser (21), the ethylene glycol liquid seal tank (24), the circulation pump (23) and the filter (22) are connected via a pipeline to form an internal circulation pipeline.

Images