VCM device purification and deacidification automatic control system

Abstract

The utility model relates to the technical field of chemical production, in particular to an automatic control system for purification and deacidification of a VCM device, and aims to solve the problems that when a falling film absorber of the VCM device for chemical production samples and analyzes at an acid discharging pipeline and judges the acid absorption condition, the operation intensity is relatively high and the working efficiency is relatively high due to the general adoption of a manual operation mode in the prior art. Meanwhile, the problem that the whole purification and deacidification efficiency is low is finally caused by being easily burnt by hydrochloric acid and the like. The system is additionally provided with a flow meter, a regulating valve, a water scrubber acid inlet pump reflux regulating valve, a switch valve, a bypass hand valve, a hydrochloric acid concentration detector and the like which are used for detecting the action of each purification and deacidification device, so that an operator can conveniently and quickly judge the purification, deacidification and acid absorption conditions through automatic control of the deacidification devices; meanwhile, system emergency shutdown caused by misoperation or untimely operation of field operators is effectively avoided, and then the potential safety hazard of acid burn in the acid sampling process of the operators is greatly avoided.

Description

Technical Field

[0001] The utility model relates to the technical field of chemical production, in particular to an automatic control system for purification and deacidification of a VCM device. Background Art

[0002] In the PVC chemical production process, the purification system at the front end of the VCM unit absorbs and purifies all unreacted high mercury, residual hydrogen chloride, and carbon dioxide in the crude vinyl chloride gas to obtain pure crude vinyl chloride gas for supply to the back end system, ultimately obtaining high-purity VCM liquid monomer. The residual hydrogen chloride is absorbed in the purification system - the falling film absorber and water scrubber using dilute acid to absorb the hydrogen chloride, and finally the hydrochloric acid with a concentration of more than 30% is transported to the hydrochloric acid separation unit for hydrogen chloride reuse. During this process, because the dilute acid in the water scrubber is often transported through CPVC pipes, the initial startup of the dynamic equipment creates a significant impact force, which can cause flange fractures in connecting pipelines. Furthermore, during initial operation, the flow and pressure of the equipment must be adjusted, and operations such as starting and stopping the equipment, cutting off pumps, and adjusting reflux must be performed. This often requires the coordinated efforts of multiple on-site operators and central control personnel. Failure to promptly address this can cause an emergency shutdown of the system, thus requiring high operator skills and emergency response capabilities. Furthermore, in the falling film absorber, on-site personnel are often required to promptly sample and analyze the acid downpipe to determine the acid absorption status of the equipment and adjust the dilute acid inlet flow rate to ensure that the acid concentration absorbed by the falling film absorber remains above 30%. However, the sampling process clearly demonstrates the low level of automation in the dynamic equipment control system. This requires high operator skills and adaptability during abnormal operations such as startup and sudden pump failures. Frequent sampling during the deacidification process ultimately increases the workload for operators and increases the risk of hydrochloric acid burns due to operator error. Utility Model Content

[0003] The utility model provides a VCM device purification and deacidification automatic control system to solve the problems existing in the above background.

[0004] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0005] A VCM device purification and deacidification automatic control system comprises a falling film absorber, the falling film absorber is connected to a water scrubber, the water scrubber is connected to a dilute hydrochloric acid tank, the dilute hydrochloric acid tank is connected to a hydrochloric acid desorption device, the hydrochloric acid desorption device is connected to a by-product hydrochloric acid tank, the by-product hydrochloric acid tank is further connected to the falling film absorber, a falling film absorber absorption liquid pipeline flowmeter is provided between the absorber and the water scrubber, the water scrubber inlet is connected to a water scrubber acid feed pump, and the water scrubber acid feed pump is connected to the outlet of the dilute hydrochloric acid tank, and the inlet of the dilute hydrochloric acid tank is also connected to the outlet of the falling film absorber.

[0006] Furthermore, the falling film absorber absorption liquid pipeline flowmeter is connected to the falling film absorber absorption liquid pipeline regulating valve, and the pipeline from the water washing tower to the water washing tower acid inlet pump is sequentially provided with a water washing tower liquid supply pipeline flowmeter, a water washing tower liquid supply pipeline regulating valve, a dilute acid main pipe flowmeter, a dilute acid main pipe remote pressure gauge, a water washing tower acid inlet pump outlet switch valve and a check valve, and a second hand valve is also provided on the pipeline between the dilute acid main pipe remote pressure gauge and the water washing tower acid inlet pump outlet switch valve.

[0007] Furthermore, the pipeline from the water washing tower acid inlet pump to the dilute hydrochloric acid tank is sequentially provided with a water washing tower acid inlet pump inlet switch valve and a second hand valve, and the output end of the dilute acid main pipe remote pressure gauge and the pipeline of the dilute hydrochloric acid tank input end are connected with a pipeline, and the second hand valve and the water washing tower acid inlet pump reflux regulating valve are sequentially provided at the connection of the pipeline.

[0008] Furthermore, a hydrochloric acid concentration detector, a lower acid regulating valve and a first manual valve are sequentially provided on the pipeline from the outlet of the falling film absorber to the by-product hydrochloric acid tank. The output end of the hydrochloric acid concentration detector is connected to the dilute hydrochloric acid tank, and a second bypass manual valve, a bypass switch valve and a first bypass manual valve are sequentially provided on the connecting pipeline, and an acid switch valve is also provided on the pipeline between the second bypass manual valve and the first bypass manual valve.

[0009] Furthermore, a by-product hydrochloric acid pump is provided between the hydrochloric acid desorption device and the by-product hydrochloric acid tank.

[0010] The utility model has the following beneficial effects:

[0011] The utility model provides an automatic control system for purification and deacidification of a VCM device. By adding structures such as a flow meter, a regulating valve, a water washing tower acid inlet pump reflux regulating valve, an on-off valve, a bypass manual valve, and a hydrochloric acid concentration detector for detecting the function of each purification and deacidification device, the operator can conveniently realize a rapid judgment of the acid absorption status of the purification and deacidification through the automatic control of the deacidification device. At the same time, it effectively avoids the emergency shutdown of the system caused by the operator's misoperation or untimely operation, thereby greatly avoiding the safety hazard of acid burns in the process of the operator taking acid samples. The utility model solves the current problem that when sampling and analyzing the acid absorption status of the falling film absorber of the chemical production VCM device at the lower acid pipeline, the common manual operation method is usually used, which usually leads to high work intensity and is very easy to be burned by hydrochloric acid, etc., which ultimately leads to low overall efficiency of purification and deacidification. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a schematic diagram of the overall structure of the utility model.

[0013] The meanings of the reference numerals are as follows:

[0014] 1. Falling film absorber; 2. Flowmeter for the absorption liquid pipeline of the falling film absorber; 3. Regulating valve for the absorption liquid pipeline of the falling film absorber; 4. Water scrubber; 5. Flowmeter for the liquid supply pipeline of the water scrubber; 6. Regulating valve for the liquid supply pipeline of the water scrubber; 7. Flowmeter for the dilute acid main pipe; 8. Remote pressure gauge for the dilute acid main pipe; 9. Reflux regulating valve for the acid feed pump of the water scrubber; 10. Outlet switching valve for the acid feed pump of the water scrubber; 11. Inlet switching valve for the acid feed pump of the water scrubber; 12. Check valve; 13. Acid feed pump of the water scrubber; 14. By-product hydrochloric acid pump; 15. By-product hydrochloric acid tank; 16. Dilute hydrochloric acid tank; 17. First bypass manual valve; 18. Bypass switching valve; 19. Lower acid switching valve; 20. Second bypass manual valve; 21. Lower acid regulating valve; 22. Hydrochloric acid concentration detector; 23. First manual valve; 24. Second manual valve; 25. Hydrochloric acid desorption device. DETAILED DESCRIPTION

[0015] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0016] like Figure 1 As shown, a VCM device purification and deacidification automatic control system includes a falling film absorber 1, the falling film absorber 1 is connected to a water scrubber 4, the water scrubber 4 is connected to a dilute hydrochloric acid tank 16, the dilute hydrochloric acid tank 16 is connected to a hydrochloric acid desorption device 25, the hydrochloric acid desorption device 25 is connected to a by-product hydrochloric acid tank 15, and the by-product hydrochloric acid tank 15 is further connected to the falling film absorber 1, and a falling film absorber absorption liquid pipeline flowmeter 2 is provided between the absorber 1 and the water scrubber 4, the inlet of the water scrubber 4 is connected to a water scrubber acid feed pump 13, and the water scrubber acid feed pump 13 is connected to the outlet of the dilute hydrochloric acid tank 16, and the inlet of the dilute hydrochloric acid tank 16 is also connected to the outlet of the falling film absorber 1.

[0017] The falling film absorber absorption liquid pipeline flowmeter 2 is connected to the falling film absorber absorption liquid pipeline regulating valve 3, and the pipeline from the water washing tower 4 to the water washing tower acid inlet pump 13 is sequentially provided with a water washing tower liquid supply pipeline flowmeter 5, a water washing tower liquid supply pipeline regulating valve 6, a dilute acid main pipe flowmeter 7, a dilute acid main pipe remote pressure gauge 8, a water washing tower acid inlet pump outlet switch valve 10 and a check valve 12, and a second hand valve 24 is also provided on the pipeline between the dilute acid main pipe remote pressure gauge 8 and the water washing tower acid inlet pump outlet switch valve 10.

[0018] The pipeline from the water washing tower acid inlet pump 13 to the dilute hydrochloric acid tank 16 is sequentially provided with a water washing tower acid inlet pump inlet switch valve 11 and a second hand valve 24. The output end of the dilute acid main pipe remote pressure gauge 8 and the pipeline of the dilute hydrochloric acid tank 16 are connected with a pipeline, and the second hand valve 24 and the water washing tower acid inlet pump reflux regulating valve 9 are sequentially provided at the connection of the pipeline.

[0019] A hydrochloric acid concentration detector 22, a lower acid regulating valve 21 and a first hand valve 23 are sequentially provided on the pipeline from the outlet of the falling film absorber 1 to the by-product hydrochloric acid tank 15. The output end of the hydrochloric acid concentration detector 22 is connected to the dilute hydrochloric acid tank 16, and a second bypass hand valve 20, a bypass switch valve 18 and a first bypass hand valve 17 are sequentially provided on the connecting pipeline, and an acid switch valve 19 is also provided on the pipeline between the second bypass hand valve 20 and the first bypass hand valve 17.

[0020] A by-product hydrochloric acid pump 14 is further provided between the hydrochloric acid desorption device 25 and the by-product hydrochloric acid tank 15 .

[0021] During the specific application of the present invention, the operator starts the acid inlet pump 13 of the water washing tower, and the equipment startup electrical signal is fed back to the water washing tower acid inlet pump inlet switch valve 11. When the valve is opened, the opening signal is transmitted to the water washing tower acid inlet pump outlet switch valve 10. The outlet valve starts to open with a delay of more than 5 seconds, and the water washing tower acid inlet pump 13 starts to run and transport dilute acid. At this time, the first bypass manual valve 17, the second bypass manual valve 20, the first manual valve 23 and the second manual valve 24 belonging to the equipment are all in the open state. Then, if the water washing tower acid inlet pump inlet switch valve 11 fails to open, the signal is fed back to the water washing tower acid inlet pump 13 control box, the water washing tower acid inlet pump 13 automatically stops running, and at the same time, the central control background appears an alarm of equipment startup failure and water washing tower acid inlet pump inlet switch valve 11 failure to open; if the water washing tower acid inlet pump outlet switch valve 10 fails to open, the signal is fed back to the water washing tower acid inlet pump 13 control box, the water washing tower acid inlet pump 13 automatically stops running, and at the same time, the central control background appears an alarm of equipment startup failure and water washing tower acid inlet pump outlet switch valve 10 failure to open. After the device is operating normally, the flow interlock is put into use. When the hydrochloric acid main pipe flow meter 7 shows a flow value of 0 for more than 3s, the interlock water washing tower acid inlet pump 13 automatically stops running, and the central control background appears an alarm of equipment flow interruption. The central control can promptly restart the equipment or switch to the standby pump, and at the same time notify the on-site personnel to check the operating status of the on-site manual valve and check valve. During normal operation, the central control personnel set the values ​​of the water washing tower liquid supply pipeline flowmeter 5 and the falling film absorber absorption liquid pipeline flowmeter 2 according to the system load demand, and then the water washing tower liquid supply pipeline regulating valve 6 and the falling film absorber absorption liquid pipeline regulating valve 3 automatically control the valve opening according to the control logic.

[0022] Furthermore, when the system load changes, the central control personnel promptly adjust the flow rate of the water washing tower 4 and the falling film absorber 1 required for acid absorption, and the signals of the water washing tower liquid supply pipeline flow meter 5 and the falling film absorber absorption liquid pipeline flow meter 2 are fed back to the water washing tower liquid supply pipeline regulating valve 6, and the opening of the falling film absorber absorption liquid pipeline regulating valve 3 changes. After the change, the pressure of the dilute acid main pipe will fluctuate. At this time, the pressure of the dilute acid main pipe remote pressure gauge 8 will change. When it is lower than the background setting value of the control system, the opening of the water washing tower acid inlet pump reflux regulating valve 9 becomes smaller; when it is higher than the background setting value of the control system, the opening of the water washing tower acid inlet pump reflux regulating valve 9 becomes larger.

[0023] At the same time, a hydrochloric acid concentration detector 22 is installed at the lower acid pipe of the purification device to detect the concentration of by-product hydrochloric acid and upload it to the central control, so that the operating personnel can adjust the falling film absorber absorption liquid pipeline flowmeter 2 in time according to the acid concentration, instead of frequent sampling by on-site operators, thereby avoiding the safety risk of acid burns.

[0024] When setting the lower limit of the by-product hydrochloric acid concentration process requirement, when the by-product hydrochloric acid concentration detected by the hydrochloric acid concentration detector 22 does not reach the lower limit of the process requirement, the signal is transmitted to the lower acid regulating valve 21 and closed; when the lower acid regulating valve 21 is closed, the closing signal is transmitted to the lower acid switch valve 19 and opened, so that the hydrochloric acid that does not meet the requirements of the hydrochloric acid desorption device 25 is re-transported to the dilute hydrochloric acid tank 16, and hydrogen chloride is absorbed again in the water washing tower 4, thereby effectively preventing low-concentration hydrochloric acid from entering the hydrochloric acid desorption device 25, causing useless operation of the hydrochloric acid desorption device 25 and waste of steam. When the acid lowering regulating valve 21 fails to close, an alarm of a failure to close the acid lowering regulating valve 21 appears on the central control background; when the acid lowering switch valve 19 fails to open, the bypass switch valve 18 is started by interlocking, and the first bypass manual valve 17 and the second bypass manual valve 20 remain normally open. At the same time, an alarm of a failure to open the acid lowering switch valve 19 appears on the central control background. After the bypass switch valve 18 fails to open again, an alarm of a failure to open the acid lowering switch valve 19 and the bypass switch valve 18 and a fault alarm of the acid lowering pipeline transportation of the falling film absorber 1 appear on the central control background. The entire automatic control and adjustment process enables the operating personnel to quickly judge the purification, deacidification and acid absorption status, and effectively avoids the emergency shutdown of the system caused by the on-site operator's misoperation or untimely operation, thereby greatly avoiding the safety hazard of acid burns in the process of the operator taking the acid sample. Therefore, the automatic control system has good practicality.

Claims

1. A VCM device purification and deacidification automatic control system, comprising a falling film absorber (1), the falling film absorber (1) being connected to a water washing tower (4), the water washing tower (4) being connected to a dilute hydrochloric acid tank (16), the dilute hydrochloric acid tank (16) being connected to a hydrochloric acid desorption device (25), the hydrochloric acid desorption device (25) being connected to a by-product hydrochloric acid tank (15), and the by-product hydrochloric acid tank (15) being further connected to the falling film absorber (1), wherein: A falling film absorber absorption liquid pipeline flowmeter (2) is provided between the absorber (1) and the water scrubber (4). The inlet of the water scrubber (4) is connected to a water scrubber acid inlet pump (13), and the water scrubber acid inlet pump (13) is connected to the outlet of the dilute hydrochloric acid tank (16). The inlet of the dilute hydrochloric acid tank (16) is also connected to the outlet of the falling film absorber (1).

2. The VCM device purification and deacidification automatic control system according to claim 1, characterized in that: The falling film absorber absorption liquid pipeline flowmeter (2) is connected to the falling film absorber absorption liquid pipeline regulating valve (3), and the pipeline from the water scrubber (4) to the water scrubber acid feed pump (13) is provided with a water scrubber liquid supply pipeline flowmeter (5), a water scrubber liquid supply pipeline regulating valve (6), a dilute acid main pipe flowmeter (7), a dilute acid main pipe remote pressure gauge (8), a water scrubber acid feed pump outlet switch valve (10) and a check valve (12) in sequence, and a second hand valve (24) is further provided on the pipeline between the dilute acid main pipe remote pressure gauge (8) and the water scrubber acid feed pump outlet switch valve (10).

3. The VCM device purification and deacidification automatic control system according to claim 2 is characterized in that: The pipeline from the water scrubber acid inlet pump (13) to the dilute hydrochloric acid tank (16) is provided with an inlet switch valve (11) of the water scrubber acid inlet pump and a second manual valve (24) in sequence. The pipeline from the output end of the dilute acid main pipe remote pressure gauge (8) and the input end of the dilute hydrochloric acid tank (16) is connected to a pipeline, and the second manual valve (24) and the water scrubber acid inlet pump reflux regulating valve (9) are provided in sequence at the connection of the pipeline.

4. The automatic control system for purification and deacidification of a VCM device according to claim 1, characterized in that: A hydrochloric acid concentration detector (22), a lower acid regulating valve (21) and a first manual valve (23) are sequentially provided on a connecting pipe from the outlet of the falling film absorber (1) to the by-product hydrochloric acid tank (15); an output end of the hydrochloric acid concentration detector (22) is connected to the dilute hydrochloric acid tank (16); a second bypass manual valve (20), a bypass switch valve (18) and a first bypass manual valve (17) are sequentially provided on the connecting pipe; and a lower acid switch valve (19) is further provided on the pipe between the second bypass manual valve (20) and the first bypass manual valve (17).

5. The VCM device purification and deacidification automatic control system according to claim 1 is characterized by: A by-product hydrochloric acid pump (14) is further provided between the hydrochloric acid desorption device (25) and the by-product hydrochloric acid tank (15).

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