Overflow weir stripper discharge buffer system for polyvinyl chloride production

Abstract

This utility model discloses an overflow weir stripping tower discharge buffer system for polyvinyl chloride (PVC) production, comprising an overflow weir stripping tower, an discharge slurry pump, a wide-channel heat exchanger, a slurry tank, and a DCS control system. The overflow weir stripping tower is connected to an discharge buffer tank, with a discharge regulating valve installed on the connecting pipeline. The discharge buffer tank is connected to the discharge slurry pump, which is connected to the wide-channel heat exchanger. The wide-channel heat exchanger is connected to the slurry tank. A level regulating valve is installed on the pipeline connecting the discharge slurry pump and the wide-channel heat exchanger, and the level regulating valve is communicatively connected to the DCS control system. The outlet of this overflow weir stripping tower is connected to the discharge buffer tank, which is equipped with a reflux pipeline. This allows the liquid level in the discharge buffer tank to be controlled within a certain range, ensuring the continuity and stability of the discharged slurry and the liquid level in the overflow weir stripping tower. This achieves continuous heat exchange between the discharged slurry and the incoming material, improving the stability of the system and product quality.

Description

Technical Field

[0001] This utility model relates to the field of polyvinyl chloride (PVC) production technology, and in particular to a PVC production overflow weir stripping tower discharge buffer system. Background Technology

[0002] In the production of polyvinyl chloride (PVC) resin, the slurry after polymerization needs to be stripped to remove residual vinyl chloride. Overflow weir stripping towers are widely used and considered advanced. During operation, the slurry outlet pipeline is typically connected directly to the inlet of the outlet slurry pump. The material passing through the pump exchanges heat with the inlet material via a heat exchanger, and the heat-exchanged material then enters a storage tank. However, when this process is applied to overflow weir stripping towers, the following problems arise: the outflow rate of the material is unstable, leading to inconsistent flow rates at the outlet pump. This makes it difficult to maintain a stable liquid level in the stripping tower, affecting the quality of the stripped material. Furthermore, the flow rate impact can damage heat exchangers and other equipment, increasing maintenance costs and the risk of production interruptions, ultimately impacting product quality. Utility Model Content

[0003] To address the aforementioned technical problems, this utility model provides a buffer system for the overflow weir stripping tower in polyvinyl chloride production. By installing a buffer tank at the discharge end of the overflow weir stripping tower, it can fundamentally solve the problem of unstable control of the material flow rate at the overflow weir and the liquid level in the stripping tower in the existing technology, significantly improving production efficiency and product quality, and has significant advantages in energy conservation, emission reduction, and equipment maintenance.

[0004] To achieve this technical objective, the present invention adopts the following solution: A buffer system for the discharge of a stripping tower in polyvinyl chloride (PVC) production includes a stripping tower, a slurry pump, a wide-channel heat exchanger, a slurry tank, and a DCS control system. The bottom outlet of the stripping tower is connected to a buffer tank. A regulating valve is installed on the pipeline connecting the stripping tower and the buffer tank. The outlet of the buffer tank is connected to the inlet of the slurry pump. The outlet pipeline of the slurry pump is connected to the wide-channel heat exchanger, which is connected to the slurry tank. A level regulating valve is installed on the pipeline connecting the slurry pump and the wide-channel heat exchanger, and the level regulating valve is communicatively connected to the DCS control system.

[0005] Compared with the prior art, the beneficial effects of this utility model are as follows: The slurry outlet of the overflow weir stripper is connected to an outlet buffer tank, which effectively reduces the impact of the hot slurry exiting the overflow weir stripper on the wide-channel heat exchanger. The outlet buffer tank is equipped with a reflux line, and an outlet feed line is installed between the bottom of the overflow weir stripper and the outlet buffer tank. This can control the liquid level in the outlet buffer tank within a certain range, ensuring the continuity and stability of the slurry exiting the tower. This ensures the stability of the liquid level in the overflow weir stripper, realizes continuous heat exchange between the slurry exiting the tower and the material entering the tower, and improves the stability of the system and product quality.

[0006] Furthermore, the outlet buffer tank is a vertical cylindrical structure with dimensions of Φ2300×2400×10mm and a volume of 10m³. 3 It is made of stainless steel.

[0007] Furthermore, a buffer tank agitator is installed on the top of the outlet buffer tank, an exhaust pipe is provided on the top of the outlet buffer tank, and a drain valve is provided at the bottom.

[0008] Furthermore, the outlet buffer tank is equipped with a liquid level sensor, which is communicatively connected to the DCS control system.

[0009] Furthermore, the slurry pump exiting the tower is a centrifugal pump, with one pump in operation and one on standby; the outlet pipeline of the slurry pump exiting the tower is equipped with a return pipeline, which is connected to the outlet buffer tank, and a manual valve is installed on the return pipeline.

[0010] Furthermore, a bottom feed line is installed at the bottom of the overflow weir stripping tower, which is connected to the outlet buffer tank. A branch bottom sewage discharge line is installed on the bottom feed line, and an automatic shut-off valve is installed, which is connected to the DCS control system. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of the overflow weir stripping tower discharge buffer system in a polyvinyl chloride production process according to one embodiment of the present invention.

[0012] Figure 2 This is a structural diagram of the outlet buffer tank in one embodiment of the present invention.

[0013] Figure 3 This is a schematic diagram of the overflow weir stripping tower sewage discharge pipeline and the material conveying pipeline in one embodiment of this utility model.

[0014] The following are marked in the diagram: 1. Overflow weir stripping tower; 2. Outlet regulating valve; 3. Outlet buffer tank; 4. Buffer tank stirring device; 5. Liquid level sensor; 6. Outlet slurry pump; 7. Bottom drain line; 8. Bottom feed line; 9. Return line; 10. Wide flow channel heat exchanger; 11. Slurry tank; 12. Liquid level regulating valve. Detailed Implementation

[0015] To fully understand the purpose, features and effects of this utility model, the following specific embodiments will be used to describe this utility model in detail, but this utility model is not limited thereto.

[0016] See Figures 1 to 3 This utility model provides a buffer system for the discharge of a stripping tower from an overflow weir in the production of polyvinyl chloride, including an overflow weir stripping tower 1, a discharge buffer tank 3, a buffer tank stirring device 4, a discharge slurry pump 6, a wide-channel heat exchanger 10, a slurry tank 11, a bottom feed line 8, a return line 9, and a DCS control system, etc.

[0017] The overflow weir stripping tower 1 is used to remove vinyl chloride from the polyvinyl chloride slurry, and the polyvinyl chloride slurry is discharged from the bottom. The bottom outlet of the overflow weir stripping tower 1 is connected to the inlet of the outlet buffer tank 3 through a pipeline equipped with an outlet regulating valve 2. The outlet buffer tank 3 is fed in the tangential direction.

[0018] The outlet buffer tank 3 is a vertical cylindrical structure with dimensions of Φ2300×2400×10mm and a volume of 10m³. 3 The material is stainless steel, the working temperature is 80~100℃, and the working pressure is atmospheric pressure. The top of the outlet buffer tank 3 is equipped with a buffer tank agitator 4, which includes an agitator motor, agitator shaft, agitator blades, and agitator mechanical seal. The bottom of the outlet buffer tank 3 is equipped with a drain valve, and the top is equipped with an exhaust pipe. The outlet buffer tank 3 is also equipped with a liquid level sensor 5, which is communicatively connected to the DCS control system to transmit data to the DCS control system.

[0019] The outlet of the slurry discharge buffer tank 3 is connected to the inlet of the slurry discharge pump 6. The slurry discharge pump 6 is a centrifugal pump, with one pump operating and one on standby, and an actual flow rate of 90~150 m³ / h. 3 The pump has a flow rate of 60-80 m / h, a head of 60-80 m, and a rated power of 60-90 kW. The outlet pipeline of the slurry pump 6 is equipped with a return pipeline 9, which is connected to the outlet buffer tank 3. A manual valve is installed on the return pipeline 9. The outlet pipeline of the slurry pump 6 is connected to a wide-channel heat exchanger 10, which is used for heat exchange between the PVC slurry entering the tower and the hot slurry exiting the tower. The wide-channel heat exchanger 10 is a wide-channel plate welded heat exchanger with a heat exchange area of ​​150-180 m². 2 A level regulating valve 12 is installed on the pipeline connecting the slurry pump 6 to the wide flow channel heat exchanger 10. The level regulating valve 12 is connected to the DCS control system and uses PID control to regulate the level of the slurry in the outlet buffer tank 3.

[0020] The bottom of the overflow weir stripping tower 1 is equipped with a bottom feed line 8, which is connected to the outlet buffer tank 3. A branch bottom sewage discharge line 7 is installed on the bottom feed line 8, and an automatic shut-off valve is provided. The automatic shut-off valve is connected to the DCS control system and can be controlled by the DCS control system.

[0021] The bottom material pipeline 8 at the bottom of the overflow weir stripping tower 1 can prevent material from accumulating inside the overflow weir stripping tower 1, and the bottom sewage pipeline 7 can perform sewage discharge operation when needed, with the shut-off valve switch controlled by the DCS control system.

[0022] The working process of the overflow weir stripping tower discharge buffer system for polyvinyl chloride production of this utility model is as follows: In the production process of polyvinyl chloride, the slurry after polymerization reaction enters the overflow weir stripping tower 1 for stripping treatment to remove residual vinyl chloride. The treated slurry flows out from the bottom outlet of the overflow weir stripping tower 1 and enters the outlet buffer tank 3 by controlling the flow rate through the outlet regulating valve 2.

[0023] In the outlet buffer tank 3, the agitator 4 stirs the slurry to prevent sedimentation. The level sensor 5 monitors the liquid level in the outlet buffer tank 3 in real time and transmits the data to the DCS control system. When the liquid level in the outlet buffer tank 3 is within the set value range of 65~75%, the system operates normally; when the liquid level drops to 40% (settable), the outlet valve of the outlet slurry pump 6 provides a minimum fixed opening to prevent the liquid level in the outlet buffer tank 3 from becoming too low.

[0024] The slurry in the outlet buffer tank 3 is pumped out by the outlet slurry pump 6. Part of it flows back to the outlet buffer tank 3 through the return pipeline 9 to ensure a certain return flow rate. The other part enters the wide flow channel heat exchanger 10 to exchange heat with the PVC slurry before entering the tower, thereby increasing the temperature of the slurry entering the tower and reducing the steam consumption during the stripping process. The slurry after heat exchange enters the subsequent slurry tank 11.

[0025] Finally, it should be noted that the above-listed embodiments are merely preferred embodiments of the present invention. Of course, those skilled in the art can make modifications and variations to the present invention. If such modifications and variations fall within the scope of the claims of the present invention and their equivalents, they should be considered as being within the protection scope of the present invention.

Claims

1. A buffer system for the discharge of a stripping tower from an overflow weir in polyvinyl chloride (PVC) production, comprising a stripping tower (1), a slurry pump (6), a wide-channel heat exchanger (10), a slurry tank (11), and a DCS control system, characterized in that, The bottom outlet of the overflow weir stripping tower (1) is connected to the outlet buffer tank (3). An outlet regulating valve (2) is installed on the pipeline connecting the overflow weir stripping tower (1) and the outlet buffer tank (3). The outlet of the outlet buffer tank (3) is connected to the inlet of the outlet slurry pump (6). The outlet pipeline of the outlet slurry pump (6) is connected to the wide flow channel heat exchanger (10). The wide flow channel heat exchanger (10) is connected to the slurry tank (11). A liquid level regulating valve (12) is installed on the pipeline connecting the outlet slurry pump (6) and the wide flow channel heat exchanger (10). The liquid level regulating valve (12) is connected to the DCS control system.

2. The overflow weir stripping tower discharge buffer system for polyvinyl chloride production according to claim 1, characterized in that, The outlet buffer tank (3) is a vertical cylindrical structure.

3. The overflow weir stripping tower discharge buffer system for polyvinyl chloride production according to claim 1, characterized in that, The top of the outlet buffer tank (3) is equipped with a buffer tank stirring device (4), the top of the outlet buffer tank (3) is equipped with an exhaust pipe, and the bottom is equipped with a drain valve.

4. The overflow weir stripping tower discharge buffer system for polyvinyl chloride production according to claim 1, characterized in that, The outlet buffer tank (3) is equipped with a liquid level sensor (5), which is connected to the DCS control system.

5. The overflow weir stripping tower discharge buffer system for polyvinyl chloride production according to claim 1, characterized in that, The slurry pump (6) is a centrifugal pump, with one pump in operation and one on standby. The outlet pipeline of the slurry pump (6) is equipped with a return pipeline (9), which is connected to the outlet buffer tank (3). A manual valve is installed on the return pipeline (9).

6. The overflow weir stripping tower discharge buffer system for polyvinyl chloride production according to claim 1, characterized in that, The bottom of the overflow weir stripping tower (1) is equipped with a bottom material pipeline (8), which is connected to the outlet buffer tank (3). A branch bottom sewage pipeline (7) is installed on the bottom material pipeline (8), and an automatic shut-off valve is provided. The automatic shut-off valve is connected to the DCS control system.

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