A vinyl chloride gas tank water seal pH value monitoring and control system

Abstract

The utility model discloses a kind of vinyl chloride gas cabinet water seal ph monitoring and regulation system, belong to vinyl chloride production equipment technical field, including vinyl chloride gas cabinet, it is characterized in that, further include liquid alkali storage tank and PLC controller, liquid alkali storage tank is equipped with infusion tube between vinyl chloride gas cabinet, infusion tube one end is connected with liquid alkali storage tank, the other end is set in vinyl chloride gas cabinet water seal, be equipped with liquid alkali metering delivery pump on infusion tube, vinyl chloride gas cabinet water seal is equipped with ph sensor, the PLC controller is electrically connected with liquid alkali metering delivery pump and ph sensor respectively.The utility model real-time acquisition water seal liquid pH value signal by ph sensor, the automatic start-stop control of liquid alkali metering delivery pump is combined with PLC controller, the real-time monitoring and accurate regulation and control of water seal liquid ph are realized, to reduce the damage of acidic corrosion to gas cabinet, prolong equipment service life.

Description

Technical Field

[0001] This utility model belongs to the technical field of vinyl chloride production equipment, and specifically relates to a system for monitoring and controlling the acidity and alkalinity of the water seal in a vinyl chloride gas holder. Background Technology

[0002] In vinyl chloride production systems, the vinyl chloride gas holder is a core piece of equipment for ensuring stable system pressure and providing buffered gas storage. It uses a water seal structure to isolate the internal vinyl chloride gas from the external atmosphere, preventing gas leaks or air contamination that could lead to safety risks. However, during long-term operation, the pH value of the water seal fluid gradually shifts towards acidity, primarily due to two key factors: First, the continuous absorption of various acidic substances from the production environment. For example, carbon dioxide in the air entering the gas holder reacts with the water seal fluid to form carbonic acid; if sulfur-containing pollutants are present near the production environment, sulfur dioxide in the air will dissolve to form sulfurous acid. Second, vinyl chloride gas undergoes a hydrolysis reaction in the water seal fluid, generating acidic products. Vinyl chloride (CH2=CHCl) belongs to the halogenated olefin family, and the carbon-chlorine bonds (C-Cl) in its molecular structure undergo a slow hydrolysis reaction in the aqueous environment of the water seal fluid. The core products of the vinyl chloride hydrolysis reaction are hydrochloric acid and acetaldehyde, which, when added to the water seal fluid, affect its pH value.

[0003] When the water seal fluid is in an acidic environment for a long time, it will cause serious corrosion to the gas holder body, pipeline interfaces and related auxiliary equipment. This will not only reduce the structural strength of the equipment, but may also cause safety hazards such as leakage and seal failure, directly affecting the stable operation of the production system and the service life of the equipment.

[0004] Currently, the industry generally uses manual monitoring and control to maintain the pH value of the water seal solution. Employees regularly test the acidity or alkalinity of the water seal solution manually using pH test strips. When the test results show that the solution is too acidic, it is necessary to manually transport the bottled liquid alkali to the gas tank water seal platform for addition.

[0005] Manual monitoring and control methods have at least the following problems: Liquid alkali is a highly corrosive medium. If it is handled improperly during manual handling and pouring, the alkali may splash, posing a high safety risk to the operator. Manual inspection generally has a relatively long cycle, poor timeliness, and low accuracy. Utility Model Content

[0006] The purpose of this invention is to provide a system for monitoring and controlling the acidity and alkalinity of the water seal in a vinyl chloride gas holder, which aims to solve the problems of poor timeliness and low accuracy of manual detection in the above-mentioned background technology, as well as the high safety risks associated with manual addition of liquid alkali.

[0007] To achieve the above objectives, the technical solution adopted by this utility model is as follows: A system for monitoring and controlling the acidity and alkalinity of a vinyl chloride gas holder water seal includes a vinyl chloride gas holder, a liquid alkali storage tank, and a PLC controller. A liquid delivery pipe is provided between the liquid alkali storage tank and the vinyl chloride gas holder. One end of the liquid delivery pipe is connected to the liquid alkali storage tank, and the other end is located in the water seal of the vinyl chloride gas holder. A liquid alkali metering and delivery pump is provided on the liquid delivery pipe. An acidity and alkalinity sensor is provided in the water seal of the vinyl chloride gas holder. The PLC controller is electrically connected to both the liquid alkali metering and delivery pump and the acidity and alkalinity sensor.

[0008] Furthermore, the liquid alkali storage tank is equipped with a liquid level sensor, and an alkali replenishment pipe is connected to the top of the liquid alkali storage tank. The alkali replenishment pipe is equipped with a regulating valve, and the liquid level sensor and the regulating valve are electrically connected to the PLC controller respectively.

[0009] Furthermore, the end of the infusion tube is connected to multiple branch pipes, and the end of each branch pipe is equipped with a nozzle, which is evenly distributed around the water seal of the vinyl chloride gas tank.

[0010] Furthermore, the infusion tubing is equipped with a check valve.

[0011] Compared with the shortcomings and deficiencies of the prior art, the present invention has the following beneficial effects.

[0012] This invention provides a system for monitoring and controlling the pH of the water seal in a vinyl chloride gas holder. It uses a pH sensor to collect the pH signal of the water seal liquid in real time, and combines this with a PLC controller to automatically start and stop the liquid alkali metering pump. This system enables real-time monitoring and precise control of the pH of the water seal liquid, solving the problems of poor timeliness, low accuracy, and safety associated with manual testing. It helps to keep the water seal liquid within a safe pH range, reducing acid corrosion damage to the gas holder and extending the equipment's service life.

[0013] In this invention, the end of the infusion tube is connected to multiple circumferentially evenly distributed nozzles via branch pipes, which can quickly and evenly spray the alkaline solution into the water seal liquid, solving the problems of excessively high local alkaline concentration and uneven mixing, improving the alkaline neutralization efficiency and control precision, and further ensuring the stability of the pH of the water seal liquid.

[0014] The liquid alkali storage tank in this invention is equipped with a liquid level sensor and a regulating valve is installed on the alkali replenishment pipeline. Both are electrically connected to the PLC controller, realizing automatic replenishment and stable liquid level control of liquid alkali. There is no need for manual monitoring of the liquid alkali inventory, which reduces the cost of manual operation and maintenance. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the connection structure of the water seal acidity and alkalinity monitoring and control system for vinyl chloride gas holder in this utility model.

[0016] Figure 2 This is a schematic diagram of the structure of the vinyl chloride gas holder with multiple nozzles arranged in a water seal according to this utility model.

[0017] Figure 3 This is a block diagram of the control relationship of the PLC controller in this utility model.

[0018] In the diagram: 1. Vinyl chloride gas holder; 2. Liquid alkali storage tank; 3. Infusion pipe; 4. Liquid alkali metering and delivery pump; 5. pH sensor; 6. Check valve; 7. Nozzle; 8. Branch pipe; 9. Liquid level sensor; 10. Alkali replenishment pipe; 11. Regulating valve; 12. PLC controller. Detailed Implementation

[0019] 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.

[0020] Reference Figure 1 A system for monitoring and controlling the acidity and alkalinity of a vinyl chloride gas holder with a water seal is disclosed. The system includes a vinyl chloride gas holder 1 and a liquid alkali storage tank 2. The top of the water seal platform of the vinyl chloride gas holder 1 has a circular structure, and the water seal isolates the internal vinyl chloride gas from the external atmosphere. The liquid alkali storage tank 2 stores liquid alkali. A delivery pipe 3 is installed between the liquid alkali storage tank 2 and the water seal platform. One end of the delivery pipe 3 is connected to the liquid alkali storage tank 2, and the other end is located at the water seal of the vinyl chloride gas holder 1. The delivery pipe 3 can be made of DN25-DN50 PVDF-lined steel pipe with an inner lining thickness of 2-3mm to accommodate corrosive media such as hydrochloric acid and liquid alkali. A liquid alkali metering and delivery pump 4 is installed on the delivery pipe 3. The alkali metering and delivery pump can be a J-X20 / 5.4 plunger-type metering pump, with SUS316 material for the flow-through components and PTFE graphite composite material for the seal, supporting 4-20mA signal control. Liquid alkali is drawn from the liquid alkali storage tank 2 by the liquid alkali metering and transfer pump 4. The liquid alkali is then introduced into the water seal through the transfer pipe 3 to adjust the pH of the liquid in the water seal and maintain the stability of the water seal pH value. A check valve 6 is installed on the transfer pipe 3 to effectively prevent backflow of the water seal liquid or alkali solution and ensure the safe operation of the pipeline.

[0021] A pH sensor 5 is installed at the water seal of the vinyl chloride gas holder 1. The pH sensor 5 can be an industrial online pH meter sensor E122T series. The pH sensor 5 is used to monitor the pH of the water seal liquid in real time. The pH sensor 5 and the liquid alkali metering and delivery pump 4 are electrically connected to the PLC controller 12. (Refer to...) Figure 3The pH sensor 5 transmits the real-time collected pH signal to the PLC controller 12. The PLC controller 12 presets a safe pH range for the water seal liquid. When the detected value is lower than the preset lower limit, the PLC controller 12 automatically starts the liquid alkali metering and delivery pump 4 to deliver liquid alkali into the water seal. When the detected value reaches the preset upper limit, the PLC controller 12 automatically shuts down the liquid alkali metering and delivery pump 4, thus achieving precise closed-loop control of pH.

[0022] The PLC controller 12 can be model S7-200 SMART SR40, equipped with analog input module EM AI04, supporting 4-20mA signal acquisition, and relay output to control pump and valve start and stop.

[0023] In one embodiment, refer to Figure 2 Multiple nozzles 7 are spaced out along the circumference of the water seal platform of the vinyl chloride gas holder 1. Each nozzle 7 is connected to a branch pipe 8, and the other end of the branch pipe 8 is connected to the infusion pipe 3. By using the circumferentially evenly distributed nozzles 7, the alkali solution can be sprayed into the water seal liquid quickly and evenly, avoiding the problem of excessively high local alkali concentration or uneven mixing, and improving the neutralization efficiency and control accuracy of the alkali solution.

[0024] In one embodiment, an alkali replenishment pipe is connected to the upper part of the liquid alkali storage tank. The alkali replenishment pipe is used to replenish alkali solution into the liquid alkali storage tank. A liquid level sensor is installed inside the liquid alkali storage tank, and a regulating valve is installed on the alkali replenishment pipe. The regulating valve and the liquid level sensor are electrically connected to the PLC controller.

[0025] In one embodiment, a replenishment pipe 10 is connected to the upper part of the liquid alkali storage tank 2. The replenishment pipe 10 is used to replenish liquid alkali into the liquid alkali storage tank 2. A liquid level sensor 9 is installed inside the liquid alkali storage tank 2. The liquid level sensor 9 can be a DBYG-600 submersible level gauge with a measurement range of 0-5m, an output of 4-20mA signal, and a probe material of 316L stainless steel. A regulating valve 11 is installed on the replenishment pipe 10. The regulating valve 11 can be a ZJHP-16C, DN40, with a valve body of SUS304, a valve core of PTFE, linear flow characteristics, and support for PLC control. The liquid level sensor 9 monitors the liquid alkali level in the liquid alkali storage tank 2 in real time and transmits the liquid level signal to the PLC controller 12. When the liquid level is lower than the preset lower limit, the PLC controller 12 automatically controls the regulating valve 11 to open and replenish alkali to the liquid alkali storage tank 2 through the alkali replenishment pipeline 10. When the liquid level reaches the preset upper limit, the PLC controller 12 automatically controls the regulating valve 11 to close, thereby realizing automatic alkali replenishment and liquid level stabilization in the liquid alkali storage tank 2.

[0026] When using the vinyl chloride gas holder water seal pH monitoring and control system, the upper and lower limits of the pH value of the water seal liquid and the upper and lower limits of the liquid level of the liquid alkali storage tank 2 are first set through the PLC controller 12. After the system is started, the pH sensor 5 continuously collects the pH value of the water seal liquid in the vinyl chloride gas holder, and the liquid level sensor 9 continuously collects the liquid level in the liquid alkali storage tank. The pH sensor 5 and the liquid level sensor 9 transmit the collected data to the PLC controller 12. According to the received signals, the PLC controller 12 automatically controls the start and stop of the liquid alkali metering and delivery pump 4 and the regulating valve 11 to complete the automated operation of pH control and liquid alkali replenishment.

[0027] 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 system for monitoring and controlling the acidity and alkalinity of a water seal in a vinyl chloride gas holder, comprising a vinyl chloride gas holder (1), characterized in that, It also includes a liquid alkali storage tank (2) and a PLC controller (12). A liquid delivery pipe (3) is provided between the liquid alkali storage tank (2) and the vinyl chloride gas holder (1). One end of the liquid delivery pipe (3) is connected to the liquid alkali storage tank (2), and the other end is set in the water seal of the vinyl chloride gas holder (1). A liquid alkali metering and delivery pump (4) is provided on the liquid delivery pipe (3). An acid-base sensor (5) is provided in the water seal of the vinyl chloride gas holder (1). The PLC controller (12) is electrically connected to the liquid alkali metering and delivery pump (4) and the acid-base sensor (5) respectively.

2. The pH monitoring and control system as described in claim 1, characterized in that, The liquid alkali storage tank (2) is equipped with a liquid level sensor (9), and the top of the liquid alkali storage tank (2) is connected to an alkali replenishment pipe (10). The alkali replenishment pipe (10) is equipped with a regulating valve (11). The liquid level sensor (9) and the regulating valve (11) are electrically connected to the PLC controller (12) respectively.

3. The pH monitoring and control system as described in claim 1, characterized in that, The infusion tube (3) is connected to a plurality of branch tubes (8), and the end of the branch tube (8) is provided with a nozzle (7), which is evenly distributed along the circumference of the water seal of the vinyl chloride gas tank (1).

4. The pH monitoring and control system as described in claim 1, characterized in that, The infusion tube (3) is equipped with a check valve (6).

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