A vinyl chloride monomer dehydration regeneration vent air staged pressure relief recovery system

Abstract

The utility model discloses a vinyl chloride monomer dewatering regeneration air release grading pressure relief recovery system belongs to vinyl chloride production equipment technical field, including the monomer dewatering device, gas cooler, booster and three section pressure swing adsorption recovery device through the pipeline connection in proper order, and is equipped with buffer tank group between monomer dewatering device and gas cooler, and buffer tank group includes the buffer tank A, buffer tank B and buffer tank C that are connected in proper order and are equipped with the valve body on the connecting pipeline, and buffer tank C is connected with gas cooler, and the release gas pipeline of monomer dewatering device is connected with buffer tank A and buffer tank B respectively, and the reverse release 2 gas pipeline of monomer dewatering device is connected with buffer tank A, buffer tank B and buffer tank C respectively, and the evacuation 2 gas pipeline of monomer dewatering device is connected with buffer tank C. The utility model discloses a grading pressure relief structure of buffer tank group, forms the ladder type pressure relief and pressure compensation, effectively reduces the gas pressure fluctuation, thereby guarantees the recovery precision of vinyl chloride and acetylene.

Description

Technical Field

[0001] This utility model belongs to the technical field of vinyl chloride production equipment, and specifically relates to a vinyl chloride monomer dehydration, regeneration, air release, pressure relief and recovery system. Background Technology

[0002] In the vinyl chloride production process, the purified and compressed crude vinyl chloride containing water enters a variable temperature and pressure monomer dehydration unit. First, the crude vinyl chloride passes through a gas-liquid separator to remove free water, and then enters a drying tower. Inside the drying tower, the moisture is retained, and qualified product gas is obtained from the top of the drying tower and sent to the distillation system.

[0003] After the drying process has been running for a period of time, the drying tower stops feeding and enters the regeneration stage. The regeneration process includes four steps: depressurization, evacuation, pressurization and hot blowing, and cold blowing. The unit dehydration device has a total of 5 drying towers, and each drying tower undergoes the following steps in sequence at different times: drying (A), reverse discharge 1 (D1), evacuation 1 (V1), displacement flushing (VP), pressurization 1 (R1), hot blowing (H), cold blowing (C), reverse discharge 2 (D2), evacuation 2 (V2), and pressurization 2 (R2).

[0004] In the above process, all the gases discharged during backflow 1 (D1), evacuation 1 (V1), and displacement flushing (VP) are recovered to the gas holder. However, the vent gas generated after hot blowing (H), the backflow gas generated after cold blowing (C), and the gas discharged during evacuation 2 contain 0.1% to 2% vinyl chloride and 0.05% to 2% acetylene. The gases generated in the above three stages flow sequentially through a gas cooler, a booster compressor, and a three-stage pressure swing adsorption recovery device, where vinyl chloride and acetylene are recovered.

[0005] However, the gases produced in the above three stages have different pressure ranges. The pressure of the vent gas produced after hot blowing (H) is about 180 kPa, the pressure range of the reverse gas 2 after cold blowing (C) is about 300 kPa, and the pressure range of the gas produced after evacuation 2 is about 70 kPa. Directly introducing the gas into the pressure swing adsorption tail gas recovery device will result in large pressure fluctuations, which will affect the recovery accuracy of the pressure swing adsorption recovery device. In addition, the recovered gas contains a certain amount of moisture, which can easily cause abnormal operation of the booster. Utility Model Content

[0006] The purpose of this invention is to provide a vinyl chloride monomer dehydration and regeneration air release and pressure recovery system, which aims to solve the problems existing in the prior art mentioned above.

[0007] To achieve the above objectives, the technical solution adopted by this utility model is as follows: A vinyl chloride monomer dehydration and regeneration venting and pressure recovery system includes a monomer dehydration device, a gas cooler, a booster compressor, and a three-stage pressure swing adsorption recovery device connected sequentially by pipelines. A buffer tank group is provided between the monomer dehydration device and the gas cooler. The buffer tank group includes buffer tank A, buffer tank B, and buffer tank C connected sequentially and equipped with valve bodies on the connecting pipelines. Buffer tank C is connected to the gas cooler. The venting gas pipeline of the monomer dehydration device is connected to buffer tank A and buffer tank B respectively. The reverse venting gas pipeline of the monomer dehydration device is connected to buffer tank A, buffer tank B, and buffer tank C respectively. The evacuation gas pipeline of the monomer dehydration device is connected to buffer tank C.

[0008] Furthermore, the pipeline between the venting pipe and the buffer tank A is equipped with valve A1, and the pipeline between the venting pipe and the buffer tank B is equipped with valve B1. The pipeline between the reverse release gas pipeline 2 and the buffer tank A is equipped with valve A2, the pipeline between the reverse release gas pipeline 2 and the buffer tank B is equipped with valve B2, and the pipeline between the reverse release gas pipeline 2 and the buffer tank C is equipped with valve C1. The pipeline between the evacuation gas pipeline 2 and the buffer tank C is equipped with valve C2.

[0009] Furthermore, the air inlet of the buffer tank A is equipped with a first remote pressure transmitter, the pipeline between the buffer tank A and the buffer tank B is equipped with a second remote pressure transmitter, and the pipeline between the buffer tank B and the buffer tank C is equipped with a third remote pressure transmitter. The pipe between buffer tank A and buffer tank B, and the valve body between buffer tank B and buffer tank C are respectively the first pressure regulating valve and the second pressure regulating valve.

[0010] Furthermore, it also includes a PLC controller, which is electrically connected to valves A1, A2, B1, B2, C1, C2, a first remote pressure transmitter, a second remote pressure transmitter, a third remote pressure transmitter, a first pressure regulating valve, and a second pressure regulating valve, respectively. When the pressure monitored by the second remote pressure transmitter is greater than 30 kPa, the first pressure regulating valve opens; When the pressure monitored by the third remote pressure transmitter is greater than 25 kPa, the second pressure regulating valve opens.

[0011] Furthermore, the bottom of buffer tanks A, B, and C are all provided with drain outlets.

[0012] Compared with the shortcomings and deficiencies of existing technologies, this utility model has the following beneficial effects: This invention provides a graded decompression and recovery system for vinyl chloride monomer dehydration and regeneration vent gas. Through a graded decompression structure consisting of buffer tanks A, B, and C, combined with the linkage control of a PLC controller, pressure transmitter, and pressure regulating valve, it provides step-by-step decompression and pressure compensation for vent gas at approximately 180 kPa, reverse vent gas at approximately 300 kPa, and evacuated gas at approximately 70 kPa. The pressure is more balanced before the gas enters the three-stage pressure swing adsorption recovery device 22, effectively reducing gas pressure fluctuations and thus ensuring the accuracy of vinyl chloride and acetylene recovery.

[0013] Buffer tanks A, B, and C are all equipped with drain outlets at the bottom. The liquid formed by the natural cooling of the three types of hot gas after entering the buffer tanks can be discharged periodically through drain outlet 23, reducing the risk of moisture entering the booster compressor with the gas, helping to reduce abnormal operation of the booster compressor, and ensuring the continuous and stable operation of the recovery system. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the pipeline connection structure of the graded pressure relief and recovery system of this utility model.

[0015] In the diagram: 1. Venting gas pipeline; 2. Backflow gas pipeline; 3. Evacuation gas pipeline; 4. Buffer tank A; 5. Buffer tank B; 6. Buffer tank C; 7. First programmable valve; 8. Second programmable valve; 9. Third programmable valve; 10. Valve A1; 11. Valve B1; 12. Valve A2; 13. Valve B2; 14. Valve C1; 15. First pressure transmitter; 16. Second remote pressure transmitter; 17. Third remote pressure transmitter; 18. First pressure regulating valve; 19. Second pressure regulating valve; 20. Gas cooler; 21. Booster compressor; 22. Three-stage pressure swing adsorption recovery device; 23. Shower port; 24. Valve C2. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present utility model and are not intended to limit the present utility model.

[0017] Reference Figure 1A graded depressurization and recovery system for vented air during the dehydration and regeneration of vinyl chloride monomer includes a monomer dehydration unit, a buffer tank group, a gas cooler 20, a booster compressor 21, and a three-stage pressure swing adsorption recovery unit 22, connected sequentially by pipelines. This graded depressurization and recovery system is used to handle the vented air from the three stages of the monomer dehydration unit's regeneration process: the vented air generated after hot blowing (H), the reverse vented air (D2) after cold blowing (C), and the gas discharged from evacuation 2 (V2). The buffer tank group enables refined graded depressurization to reduce gas pressure fluctuations introduced into the three-stage pressure swing adsorption recovery unit 22, thereby ensuring the recovery efficiency of vinyl chloride and acetylene in the gas and the stability of the equipment.

[0018] The individual dehydration unit is connected to a venting gas pipe 1, a reverse venting gas pipe 2, and an evacuation gas pipe 3. Venting gas pipe 1 is used to discharge the venting gas generated after the hot blowing (H) process is completed; reverse venting gas pipe 2 is used to discharge the reverse venting gas after the cold blowing (C) process is completed; and evacuation gas pipe 3 is used to discharge the gas discharged from evacuation 2 (V2). Venting gas pipe 1, reverse venting gas pipe 2, and evacuation gas pipe 3 are respectively equipped with a first control valve 7, a second control valve 8, and a third control valve 9.

[0019] The buffer tank assembly includes buffer tanks A4, B5, and C6 connected by pipelines. Buffer tank C6 is sealed to the gas cooler 20, forming a continuous channel for gas flow. The three-stage pressure swing adsorption recovery unit 22 is connected to a finished product recovery pipeline and a tail gas emission pipeline, respectively. The finished product recovery pipeline is used to discharge the recovered vinyl chloride and acetylene, and the tail gas emission pipeline is used to discharge qualified tail gas.

[0020] The venting pipe 1 is connected to buffer tank A4 and buffer tank B5 respectively, and valve A1 10 is installed between venting pipe 1 and buffer tank A4, and valve B1 11 is installed on the pipe between venting pipe 1 and buffer tank B5.

[0021] The reverse release gas pipeline 2 is connected to buffer tanks A4, B5, and C6 respectively. A valve A2 12 is installed between the reverse release gas pipeline 2 and buffer tank A4, a valve B2 13 is installed between the reverse release gas pipeline 2 and buffer tank B5, and a valve C1 14 is installed on the pipeline between the reverse release gas pipeline 2 and buffer tank C6.

[0022] The evacuation gas pipeline 3 is connected to the buffer tank C6, and valve C2 24 is installed on the pipeline between the evacuation gas pipeline 3 and the buffer tank C6.

[0023] Valve A1 (10), A2 (12), B1 (11), B2 (13), C1 (14), C2 (24), the first programmable valve (7), the second programmable valve (8), and the third programmable valve (9) are electrically connected to an external PLC controller, enabling remote and precise control of the on / off status of each pipeline and improving the system's automation level. All of the above valves can be electrically operated programmable ball valves, specifically the commercially available Q941F-25P series, with a nominal pressure of 2.5MPa, meeting the system's maximum working pressure requirement of 300kPa. These valves support 4-20mA analog signal control and can be linked with the PLC controller.

[0024] A first pressure transmitter 15 is installed at the air inlet of buffer tank A4 to monitor the air pressure in the pipeline before entering buffer tank A4 in real time; a second remote pressure transmitter 16 is installed in the pipeline between buffer tank A4 and buffer tank B5 to monitor the air pressure inside buffer tank A4 in real time; a third remote pressure transmitter 17 is installed in the pipeline between buffer tank B5 and buffer tank C6 to monitor the air pressure inside buffer tank B5 in real time.

[0025] The first remote pressure transmitter 15, the second remote pressure transmitter 16, and the third remote pressure transmitter 17 are of the same model and can be intelligent diffused silicon remote pressure transmitters. The specific model can be the commercially available Rosemount 3051GP, which can cover the actual pressure range of 70-300kPa in the system to ensure measurement accuracy. With an accuracy class of 0.075, it can capture subtle changes such as pressure fluctuations in the buffer tank in real time, providing accurate data support for PLC controller control, and outputting a 4-20mA standard current signal.

[0026] The pipeline between buffer tank A4 and buffer tank B5 is equipped with a first pressure regulating valve 18, and the pipeline between buffer tank B5 and buffer tank C6 is equipped with a second pressure regulating valve 19.

[0027] The first pressure transmitter 15, the second remote pressure transmitter 16, the third remote pressure transmitter 17, the first pressure regulating valve 18, and the second pressure regulating valve 19 are electrically connected to the PLC controller, and the control logic is preset by the PLC controller. When the air pressure in buffer tank A4 is greater than 30 kPa, the first pressure regulating valve 18 automatically opens; when the air pressure in buffer tank B5 is greater than 25 kPa, the second pressure regulating valve 19 automatically opens, realizing pressure compensation regulation.

[0028] The first pressure regulating valve 18 and the second pressure regulating valve 19 are of the same model. Specifically, the commercially available ZJHP-16P / 25P pneumatic diaphragm single-seat regulating valve can be used, with a nominal pressure of 1.6 MPa / 2.5 MPa, a leakage class of VI, and the ability to accept 4–20mA signals. It can form a closed-loop control system with a PLC controller and a pressure transmitter.

[0029] In one embodiment, the bottom of buffer tanks A4, B5, and C6 are all equipped with drain ports 23. Since the three types of exhaust gases generated by the individual dehydration unit are all hot gases, they will form liquid and settle at the bottom of the tank after natural cooling upon entering the buffer tank. The drain ports 23 are used to periodically drain the liquid to prevent moisture from affecting the operation of subsequent equipment.

[0030] When using this vinyl chloride monomer dehydration and regeneration air release staged pressure relief and recovery system: 1. During the regeneration process of the monomer dehydration device, the vent gas generated after the hot blowing (H) is completed has a gas pressure of 180 kPa inside the monomer dehydration device.

[0031] First, open valve A1 10 to connect the venting pipe 1 to buffer tank A 4. The first pressure transmitter 15 monitors the gas pressure in the venting pipe in real time. When the gas pressure drops to 140 kPa, close valve A1 10 to complete the first stage of pressure relief.

[0032] The second step is to open valve B11, which switches the venting pipe 1 to connect with buffer tank B5, and continuously vent pressure.

[0033] During the aforementioned depressurization process, the second remote pressure transmitter 16 monitors the gas pressure inside buffer tank A4 in real time. When the gas pressure exceeds 30 kPa, the first pressure regulating valve 18 automatically opens, connecting buffer tank A4 with buffer tank B5 to achieve pressure compensation. The third remote pressure transmitter 17 monitors the gas pressure inside buffer tank B5 in real time. When the gas pressure exceeds 25 kPa, the second pressure regulating valve 19 automatically opens, connecting buffer tank B5 with buffer tank C6 to further equalize the pressure. The released gas after multi-stage depressurization flows sequentially through gas cooler 20 and booster compressor 21, and finally enters the three-stage pressure swing adsorption recovery device 22 to complete the recovery of vinyl chloride and acetylene.

[0034] 2. During the regeneration process of the monomer dehydration device, after the cold blowing (C) is completed, the gas is released in reverse. At this time, the gas pressure inside the monomer dehydration device is 300 kPa.

[0035] First, open valve A2 12 to connect gas pipeline 2 of reverse release 2 to buffer tank A 4. The first pressure transmitter 15 monitors the gas pressure in the pipeline in real time. When the gas pressure drops to 200 kPa, close valve A2 12 to complete the first stage of pressure relief.

[0036] The second step is to open valve B2 13 to switch the reverse release gas pipeline 2 to connect with buffer tank B 5 for continuous pressure relief. When the gas pressure drops to 100 kPa, close valve B2 13 to complete the second stage of pressure relief.

[0037] The third step is to open valve C1 14, which switches the reverse release gas pipeline 2 to connect with buffer tank C 6, thus completing the final depressurization.

[0038] During the aforementioned pressure relief process, the second remote pressure transmitter 16 monitors the gas pressure of buffer tank A4. When it exceeds 30 kPa, the first pressure regulating valve 18 automatically opens. The third remote pressure transmitter 17 monitors the gas pressure of buffer tank B5. When it exceeds 25 kPa, the second pressure regulating valve 19 automatically opens. Pressure equalization is achieved through the connection between the buffer tanks. After the pressure stabilizes, the reverse-released gas flows sequentially through the gas cooler 20 and the booster 21, and then enters the three-stage pressure swing adsorption recovery device 22 to recover vinyl chloride and acetylene.

[0039] 3. During the regeneration process of the monomer dehydration device, the gas discharged from evacuation unit 2 (V2) is evacuated. At this time, the gas pressure inside the monomer dehydration device is 70 kPa.

[0040] Open valve C2 24. At this time, the evacuation gas pipeline 3 is connected to the buffer tank C 6. The pressure is released and stabilized through the buffer tank C 6. The stabilized gas flows through the gas cooler 20 and the booster 21 in sequence, and enters the three-stage pressure swing adsorption recovery device 22 to recover vinyl chloride and acetylene.

[0041] During daily use, the accumulated liquid needs to be drained periodically through the drain outlet 23 at the bottom of buffer tanks A4, B5, and C6 to ensure the continuous and stable operation of the system. The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A vinyl chloride monomer dehydration and regeneration air release staged depressurization and recovery system, comprising a monomer dehydration device, a gas cooler (20), a booster compressor (21), and a three-stage pressure swing adsorption recovery device (22) connected sequentially by pipelines, characterized in that, A buffer tank group is provided between the unit dehydration device and the gas cooler (20). The buffer tank group includes buffer tank A (4), buffer tank B (5) and buffer tank C (6) connected in sequence and equipped with valve bodies on the connecting pipeline. The buffer tank C (6) is connected to the gas cooler (20). The gas venting pipe (1) of the unit dehydration device is connected to buffer tank A (4) and buffer tank B (5) respectively. The gas venting pipe (2) of the unit dehydration device is connected to buffer tank A (4), buffer tank B (5) and buffer tank C (6) respectively. The gas evacuation pipe (3) of the unit dehydration device is connected to buffer tank C (6).

2. The staged pressure relief and recovery system as described in claim 1, characterized in that, The pipeline between the venting gas pipeline (1) and the buffer tank A (4) is equipped with valve A1 (10), and the pipeline between the venting gas pipeline (1) and the buffer tank B (5) is equipped with valve B1 (11); the pipeline between the reverse venting gas pipeline (2) and the buffer tank A (4) is equipped with valve A2 (12), the pipeline between the reverse venting gas pipeline (2) and the buffer tank B (5) is equipped with valve B2 (13), the pipeline between the reverse venting gas pipeline (2) and the buffer tank C (6) is equipped with valve C1 (14); the pipeline between the evacuation gas pipeline (3) and the buffer tank C (6) is equipped with valve C2 (24).

3. The staged pressure relief and recovery system as described in claim 2, characterized in that, The air inlet of the buffer tank A (4) is equipped with a first remote pressure transmitter (15), the pipeline between the buffer tank A (4) and the buffer tank B (5) is equipped with a second remote pressure transmitter (16), and the pipeline between the buffer tank B (5) and the buffer tank C (6) is equipped with a third remote pressure transmitter (17); the pipeline between the buffer tank A (4) and the buffer tank B (5), and the valve body between the buffer tank B (5) and the buffer tank C (6) are respectively a first pressure regulating valve (18) and a second pressure regulating valve (19).

4. The staged pressure relief and recovery system as described in claim 3, characterized in that, It also includes a PLC controller, which is electrically connected to valves A1 (10), A2 (12), B1 (11), B2 (13), C1 (14), C2 (24), a first remote pressure transmitter (15), a second remote pressure transmitter (16), a third remote pressure transmitter (17), a first pressure regulating valve (18), and a second pressure regulating valve (19), respectively; when the second remote pressure transmitter (16) monitors a pressure greater than 30 kPa, the first pressure regulating valve (18) opens; when the third remote pressure transmitter (17) monitors a pressure greater than 25 kPa, the second pressure regulating valve (19) opens.

5. The staged pressure relief and recovery system as described in claim 1, characterized in that, The bottom of buffer tanks A (4), B (5) and C (6) are all provided with drain outlets (23).

Images