Vacuum suction device for recycled polyester

Abstract

The utility model discloses a recycled polyester vacuum suction device, which comprises a polycondensation kettle, a condenser, a cyclone separator and a three-stage jet pump, a tail gas outlet is arranged at the top of the polycondensation kettle, the inlet end of the condenser is connected with a tail gas outlet pipeline of the polycondensation kettle, and the outlet end of the condenser is connected to the lateral upper part of the cyclone separator. The top of the cyclone separator is provided with a separated gas outlet, the separated gas outlet at the top of the cyclone separator is connected to a three-stage injection pump through a pipeline, vacuum suction force is generated through the three-stage injection pump, and a control valve set is installed on a connecting pipeline of the three-stage injection pump and the cyclone separator. According to the utility model, the structure combining the condenser and the cyclone separator is adopted to replace a spraying system, and the vacuumizing operation of the polycondensation kettle is divided into two stages, namely a low vacuum stage and a high vacuum stage, which are carried out in sequence, so that the device has the advantages of small occupied area, low investment cost, high efficiency and the like. And the blockage failure rate of a vacuum system is low.

Description

Technical Field

[0001] This utility model relates to the field of chemical production equipment technology, and more specifically, to a vacuum suction device for recycled polyester. Background Technology

[0002] The polycondensation vacuum system installed in existing polyester production facilities generally consists of a spray system, a three-stage jet pump, and a liquid ring vacuum pump. The polycondensation vacuum system is used to remove ethylene glycol (EG) and oligomers generated during the polycondensation process. The tail gas from the polycondensation reactor passes through the spray system and is then connected to the first stage jet pump of the three-stage jet pump. The final tail gas generated by the three-stage jet pump is then pumped out by the liquid ring vacuum pump. The main structure of the spray system includes a scraper condenser, which mainly consists of a vertical cylinder and a horizontal cylinder. The horizontal cylinder is connected to the lower end of the vertical cylinder. The inner cavity of the vertical cylinder is equipped with condensing nozzles, which are connected to the spray pipe. The top of the vertical cylinder is equipped with a tail gas extraction port connected to a three-stage jet pump. The inner cavity of the horizontal cylinder is equipped with a scraper rotor, and the scraper is adapted to the inner wall of the horizontal cylinder. The upper part of the front end of the horizontal cylinder is equipped with a scraper air inlet, and the lower part of the rear end of the horizontal cylinder is equipped with a scraper medium outlet. The scraper medium outlet is connected to the hot well through a large air leg. The EG outlet at the bottom of the hot well is connected to the inlet of the spray circulation pump. The outlet of the spray circulation pump is connected to the spray pipe through an ethylene glycol circulation pipe.

[0003] The existing polycondensation vacuum system has the following shortcomings: 1. It adopts a complex and bulky spray system, which not only has high investment costs for the entire system, but also requires a large area; 2. Due to the production characteristics of the recycled intermittent polyester unit, there are a large number of entrained materials in the exhaust gas. These entrained materials can easily cause blockage of the vacuum system, reduce the system's vacuuming capacity, and thus affect product quality. Utility Model Content

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a vacuum suction device for recycled polyester. This invention replaces the spray system by adopting a structure combining a condenser and a cyclone separator. It also divides the vacuuming operation of the polycondensation kettle into two stages: a low vacuum stage and a high vacuum stage, which are carried out sequentially. Under the above design, this invention has a series of advantages such as small equipment footprint, low investment cost, and low blockage failure rate of the vacuum system.

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

[0006] A vacuum suction device for recycled polyester includes a polycondensation reactor, a condenser, a cyclone separator, and a three-stage jet pump. The top of the polycondensation reactor has a tail gas outlet. The inlet end of the condenser is connected to the tail gas outlet pipeline of the polycondensation reactor. The outlet end of the condenser is connected to the upper side of the cyclone separator. The top of the cyclone separator has a separation gas outlet. The separation gas outlet pipeline at the top of the cyclone separator is connected to the three-stage jet pump. The three-stage jet pump generates a vacuum suction force. A control valve assembly is installed on the connecting pipeline between the three-stage jet pump and the cyclone separator.

[0007] Furthermore, the inlet end of the condenser is connected to the tail gas outlet of the polycondensation reactor by a gas phase pipe.

[0008] Furthermore, a demister is installed between the cyclone separator and the three-stage jet pump. A first pipe is installed between the demister inlet and the separated gas outlet at the top of the cyclone separator, and a second pipe is installed between the demister outlet and the three-stage jet pump. The control valve assembly is installed on the second pipe.

[0009] Furthermore, the demister is filled with Pall ring packing.

[0010] Furthermore, the control valve group includes a first electric valve and a second electric valve, which are connected in parallel and open alternately.

[0011] Furthermore, the first electric valve is an electric valve with a diameter not greater than DN50, and the second electric valve is an electric valve with a diameter not less than DN200.

[0012] Furthermore, the first electric valve opens before the second electric valve.

[0013] The beneficial effects of this utility model are:

[0014] 1. This utility model replaces the spray system by adopting a structure that combines a condenser and a cyclone separator, which can not only meet production needs, but also reduce equipment investment costs and workshop space requirements.

[0015] 2. This utility model designs a control valve group to control the vacuuming operation of the polycondensation reactor. The vacuuming of the polycondensation reactor can be divided into two stages. The first stage is the low vacuum stage, where the vacuum level drops to 7-8 kPa. The second stage is the high vacuum stage, where the vacuum level drops to 100-200 Pa. The two stages are carried out sequentially. The two-stage vacuum control not only meets the system's requirements for vacuum control, but also effectively reduces material entrainment in the exhaust gas, thus greatly reducing the blockage failure rate of the vacuum system. Attached Figure Description

[0016] Figure 1This is a connection principle diagram of a recycled polyester vacuum suction device in this embodiment.

[0017] Figure reference numerals: 1. Polycondensation reactor; 2. Gas phase pipe; 3. Condenser; 4. Cyclone separator; 41. First pipe; 42. Second pipe; 5. Demister; 6. Three-stage jet pump; 7. Control valve group; 71. First electric valve; 72. Second electric valve. Detailed Implementation

[0018] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0019] like Figure 1 The illustrated regenerated polyester vacuum suction device includes a polycondensation reactor 1, a condenser 3, a cyclone separator 4, and a three-stage jet pump 6. The polycondensation reactor 1 has a tail gas outlet at its top. The polycondensation reactor 1 is used for polyester chemical production. The tail gas generated by the polyester chemical reaction is extracted through the tail gas outlet at the top of the polycondensation reactor 1. The three-stage jet pump 6 generates vacuum suction force to form a tail gas vacuum extraction path within the entire device. The inlet end of the condenser 3 is connected to the tail gas outlet pipeline of the polycondensation reactor 1. The extracted tail gas is first cooled by the condenser 3, and the outlet end of the condenser 3 is connected to... The cyclone separator 4 is located on the upper side and below the condenser 3. The cooled gas naturally enters the cyclone separator 4, which achieves gas-solid separation. Most of the entrained material in the gas (a small amount of material is also carried away with the exhaust gas from the condensation reactor 1, which is the main cause of vacuum system blockage) falls and accumulates at the bottom of the cyclone separator 4. The top of the cyclone separator 4 has a separated gas outlet, which is connected to a three-stage jet pump 6. The separated gas is discharged through the pipeline to the three-stage jet pump 6. Figure 1As shown, a demister 5 is installed between the cyclone separator 4 and the three-stage jet pump 6. A first pipe 41 connects the inlet of the demister 5 to the separated gas outlet at the top of the cyclone separator 4, and a second pipe 42 connects the outlet of the demister 5 to the three-stage jet pump 6. The demister 5 is installed in the middle section of the connecting pipe between the cyclone separator 4 and the three-stage jet pump 6, dividing the connecting pipe into two parts: the first pipe 41 and the second pipe 42. Although the cyclone separator 4 can achieve gas-solid separation, non-condensable gases and a small amount of entrained matter will still continue to be discharged through the separated gas outlet at the top of the cyclone separator 4. The demister 5 plays a secondary role in intercepting entrained matter, and finally only non-condensable gases enter the three-stage jet pump 6. The new system replaces the traditional spray system with a combination of condenser 3 and cyclone separator 4. Compared with the traditional spray system, the purchase and installation costs of condenser 3 and cyclone separator 4 are lower, the equipment occupies less space, and there is no need to invest a large space for installation. Moreover, after adding demister 5, the removal rate of entrained materials in the system is greatly improved, which is conducive to the stable operation of the vacuum suction device. In order to reduce the blockage failure rate of the vacuum system, this invention installs a control valve group 7 on the connecting pipeline between the three-stage jet pump 6 and the cyclone separator 4. The control valve group 7 is installed on the second pipeline 42. The control valve group 7 can accurately and stably control the system vacuum degree, and control the content of entrained materials in the exhaust gas by changing the system vacuum degree.

[0020] The inlet of the condenser 3 is connected to the tail gas outlet of the polycondensation kettle 1 by a gas phase pipe 2. The gas phase pipe 2 plays a role in the stable transmission of chemical gases and is widely used in chemical equipment. The first pipeline 41 and the second pipeline 42 can also be gas phase pipes.

[0021] The demister 5 is filled with Pall ring packing, which gives the demister 5 a good effect in removing entrained materials.

[0022] The control valve assembly 7 includes a first electric valve 71 and a second electric valve 72, which are connected in parallel. The opening of either valve does not affect the flow of the pipeline. The first electric valve 71 is a valve with a diameter no greater than DN50, and the second electric valve 72 is a valve with a diameter no less than DN200. When the first electric valve 71 is open, it is in the low vacuum stage, with the vacuum level gradually decreasing and maintained at 7-8 kPa. When the second electric valve 72 is open, it is in the high vacuum stage, with the vacuum level decreasing and maintained at 100-200 Pa. The first electric valve 71 and the second electric valve 72 are designed to open alternately. In actual use, the first electric valve 71 opens before the second electric valve 72, and the system enters the low vacuum stage first. Because the opening of the first electric valve 71 is relatively small, the suction volume is not large, resulting in a relatively flat vacuum drop curve. This helps to reduce the amount of material entrained in the exhaust gas. After the first electric valve 71 is open for a period of time, the system switches to the second electric valve 72, and the system enters the high vacuum stage. Although the vacuum suction volume increases as the opening of the second electric valve 72 increases, the amount of material entrained in the exhaust gas does not increase significantly (because a large amount of material has already reacted and polymerized during the low vacuum stage, the amount of material that can be entrained in the exhaust gas has been significantly reduced). This design of alternating opening of the first electric valve 71 and the second electric valve 72 can effectively reduce the amount of material entrained in the exhaust gas. With a significant drop in the amount of material entrained, the amount of material entering the vacuum system is significantly reduced, and the blockage failure rate of the vacuum system will be significantly lower.

[0023] Both the cyclone separator 4 and the condenser 3 of this invention have pipes for introducing steam and cooling water. When switching production varieties or periodically cleaning the reactor, steam can be connected to the pipes to facilitate cleaning of the cyclone separator 4 and the condenser 3. This can effectively reduce the generation of transition material and improve product quality.

[0024] The above description is merely a preferred embodiment of this utility model. The protection scope of this utility model is not limited to the above embodiments. All technical solutions falling within the scope of this utility model's concept are protected. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principle of this utility model should also be considered within the protection scope of this utility model.

Claims

1. A regenerative polyester vacuum suction device, characterized by The polycondensation kettle (1) is provided with a tail gas outlet at the top, the inlet end of the condenser (3) is connected with the tail gas outlet pipeline of the polycondensation kettle (1), the outlet end of the condenser (3) is connected to the upper side of the cyclone separator (4), the cyclone separator (4) is provided with a separated gas outlet at the top, the separated gas outlet pipeline at the top of the cyclone separator (4) is connected to the three-stage jet pump (6), the vacuum suction force is generated through the three-stage jet pump (6), and the control valve group (7) is installed on the connecting pipeline between the three-stage jet pump (6) and the cyclone separator (4).

2. The regenerated polyester vacuum suction device according to claim 1, wherein The inlet end of the condenser (3) is connected with the tail gas outlet of the polycondensation kettle (1) through a gas phase pipeline (2).

3. The regenerated polyester vacuum suction device according to claim 1, wherein The mist eliminator (5) is installed between the cyclone separator (4) and the three-stage jet pump (6), the first pipeline (41) is installed between the inlet of the mist eliminator (5) and the separated gas outlet at the top of the cyclone separator (4), the second pipeline (42) is installed between the outlet of the mist eliminator (5) and the three-stage jet pump (6), and the control valve group (7) is installed on the second pipeline (42).

4. The regenerated polyester vacuum suction device according to claim 3, wherein The mist eliminator (5) is filled with Pall ring fillers.

5. The regenerated polyester vacuum suction device according to claim 1, wherein The control valve group (7) comprises a first electric valve (71) and a second electric valve (72), the first electric valve (71) and the second electric valve (72) are connected in parallel, and the first electric valve (71) and the second electric valve (72) are alternately opened.

6. The regenerated polyester vacuum suction device according to claim 5, wherein The first electric valve (71) is an electric valve with a caliber not greater than DN50, and the second electric valve (72) is an electric valve with a caliber not less than DN200.

7. The regenerated polyester vacuum suction device according to claim 5, wherein The first electric valve (71) is opened before the second electric valve (72).

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