Automatic switching device for liquid chlorine storage tank

Abstract

The invention relates to the technical field of chlorine liquefaction production devices, in particular to a liquid chlorine storage tank automatic switching device which comprises a DCS controller, an in-use storage tank, a standby storage tank, an in-use storage tank discharging pipeline, a standby storage tank discharging pipeline, a discharging main pipeline, a liquid chlorine pipeline, a chlorine pipeline and a waste chlorine main pipeline. A second stop valve is arranged on the standby storage tank discharging pipeline, the in-use storage tank discharging pipeline and the standby storage tank discharging pipeline are connected into a main discharging pipeline, and a third stop valve is arranged on the main discharging pipeline. The system further comprises a process gas pipeline, the process gas pipeline is connected with the top of the in-use storage tank, and a stop valve IV is arranged on the process gas pipeline; the first stop valve, the second stop valve, the third stop valve and the fourth stop valve are connected with the DCS controller. According to the device, medium switching between the in-use storage tank and the standby storage tank is achieved through process gas pressure, the switching process is simplified, operation accidents are reduced, and safety and environmental protection risks are reduced.

Description

Technical Field

[0001] This invention relates to the technical field of chlorine liquefaction production equipment in the chlor-alkali industry, specifically an automatic switching device for liquid chlorine storage tanks. Background Technology

[0002] Currently, the chlor-alkali industry mainly relies on the combined operation of transfer pumps and return pipelines to transfer the medium between in-use and standby tanks for switching liquid chlorine storage tanks. The specific operation process is as follows: First, check the status of relevant pipeline valves of the standby tank, open the return pipeline valve to the standby tank, start the transfer pump to transfer liquid chlorine to the standby tank, and then close the outlet valve of the in-use tank and the return valve of the standby tank after the tank transfer is completed. This traditional operation mode has the following significant problems: During the operation, operators need to enter the site and handle the process manually throughout, and the process needs to be carried out step by step, which is cumbersome and has a low level of automation; Second, liquid chlorine is a highly toxic and hazardous chemical, and there is a significant risk of poisoning during on-site operations. If operators make operational errors or delay emergency response, it can easily lead to serious environmental safety accidents; Third, the production system is usually equipped with multiple tanks, and each tank involves multiple process pipelines such as feed, discharge, pressure balancing, return, and waste chlorine. In an emergency, operating each item one by one can easily lead to misoperation. In addition, the use of liquid chlorine pressurization pumps as power sources may itself be a potential risk point for escalation of accidents. Summary of the Invention

[0003] To address the shortcomings of existing technologies, the purpose of this invention is to provide an automatic switching device for liquid chlorine storage tanks, which can improve the intelligence level of liquid chlorine storage tank switching operations and achieve the safety requirement of unmanned on-site operation.

[0004] The technical solution adopted by this invention to solve its technical problem is: An automatic switching device for liquid chlorine storage tanks includes a DCS controller, a used storage tank, a standby storage tank, a discharge pipeline for the used storage tank, a discharge pipeline for the standby storage tank, a main discharge pipeline, a liquid chlorine pipeline, a chlorine gas pipeline, and a waste chlorine gas main pipeline. A shut-off valve one is installed on the discharge pipeline for the used storage tank, and a shut-off valve two is installed on the discharge pipeline for the standby storage tank. The discharge pipelines for the used and standby storage tanks are respectively connected to the main discharge pipeline, which is equipped with a shut-off valve three. The device also includes a process gas pipeline connected to the top of the used storage tank, and a shut-off valve four is installed on the process gas pipeline. Shut-off valves one, two, three, and four are respectively connected to the DCS controller.

[0005] Compared with the prior art, the beneficial effects of the present invention are: This device, in conjunction with the process flow setup and DCS control, enables the switching of media between in-use and standby storage tanks via process gas pressure. It avoids the drawbacks of requiring on-site confirmation and operation for pump backflow and the need for a liquid chlorine transfer pump to deliver high-pressure liquid chlorine, which could escalate the situation. It improves the intelligence level of liquid chlorine storage tank switching operations, meets the safety requirements of unmanned on-site operation, simplifies the liquid chlorine storage tank switching process, reduces the occurrence of operational accidents, and lowers safety and environmental risks.

[0006] As a preferred embodiment, a further technical solution of the present invention is: Preferably, it also includes a three-way valve and a waste chlorine gas pipeline. The process gas pipeline includes pipeline one and pipeline two. Pipeline one, pipeline two, and waste gas pipeline one are connected by the three-way valve. A check valve is installed on pipeline one, and a shut-off valve four is placed on pipeline two. Waste chlorine gas pipeline one is connected to the main waste chlorine gas pipeline. The check valve and the three-way valve can prevent chlorine gas in the storage tank from flowing back into the process gas pipeline and affecting normal production.

[0007] Preferably, a self-regulating valve is also installed on the pipeline, which is positioned between the check valve and the three-way valve.

[0008] Preferably, the main discharge pipeline is connected to the discharge pipelines of the in-use storage tank and the standby storage tank via a three-way valve.

[0009] Preferably, a waste chlorine gas pipeline 2 is installed on the top of the storage tank in use, and a waste chlorine gas pipeline 3 is installed on the top of the standby storage tank. Waste chlorine gas pipeline 2 and waste chlorine gas pipeline 3 are respectively connected to the main waste chlorine gas pipeline. A shut-off valve 5 is installed on waste chlorine gas pipeline 2, and a pressure relief valve is installed on waste chlorine gas pipeline 3. The shut-off valve 5 and the pressure relief valve are respectively connected to the DCS controller. Attached Figure Description

[0010] Figure 1 This is a schematic diagram of the existing process flow; Figure 2 This is a schematic diagram of the process flow of the present invention; Explanation of reference numerals in the attached diagram: 1. Discharge pipeline of the in-use storage tank; 2. Discharge pipeline of the standby storage tank; 3. Main discharge pipeline; 4. Liquid chlorine pipeline; 5. Chlorine gas pipeline; 6. Main waste chlorine gas pipeline; 7. Three-way valve 2; 8. Shut-off valve 1; 9. Shut-off valve 2; 10. Shut-off valve 3; 11. Liquid chlorine transfer pump; 12. Pipeline 1; 13. Pipeline 2; 14. Check valve; 15. Shut-off valve 4; 16. Three-way valve 1; 17. Self-regulating valve; 18. Waste chlorine gas pipeline 2; 19. Waste chlorine gas pipeline 3; 20. Shut-off valve 5; 21. Pressure relief valve; 22. Waste chlorine gas pipeline 1. Detailed Implementation

[0011] The present invention will be further illustrated below with reference to specific embodiments. The purpose of this illustration is solely to provide a better understanding of the invention. Therefore, the examples given do not limit the scope of protection of the present invention.

[0012] An automatic switching device for liquid chlorine storage tanks comprises a DCS controller, a used storage tank, a standby storage tank, a discharge pipeline 1 for the used storage tank, a discharge pipeline 2 for the standby storage tank, a main discharge pipeline 3, a liquid chlorine pipeline 4, a chlorine gas pipeline 5, a waste chlorine gas main pipeline 6, a three-way valve 16, and a waste chlorine gas pipeline 22.

[0013] The tops of the active storage tank and the standby storage tank are respectively connected to liquid chlorine pipeline 4, and the tops of the active storage tank and the standby storage tank are respectively connected to chlorine gas pipeline 5.

[0014] The discharge pipeline 1 of the in-use storage tank is located at the bottom of the in-use storage tank, and the discharge pipeline 2 of the standby storage tank is located at the bottom of the standby storage tank. The in-use storage tank pipeline and the standby storage tank pipeline are connected to one end of the main discharge pipeline 3 via a three-way valve 2 7. A shut-off valve 1 8 is installed on the discharge pipeline 1 of the in-use storage tank, a shut-off valve 2 9 is installed on the discharge pipeline 2 of the standby storage tank, and a shut-off valve 3 10 is installed on the main discharge pipeline 3. The other end of the main discharge pipeline 3 is connected to a liquid chlorine transfer pump 11, which transports the liquid chlorine in the storage tank to the cylinder, tank truck loading / unloading, or return pipeline.

[0015] The top of the storage tank is also connected to a process gas pipeline 12, which consists of pipeline 12 and pipeline 23. Pipeline 12, pipeline 23 and waste chlorine pipeline 22 are connected by a three-way valve 16. A one-way valve 14 is installed on pipeline 12, and a shut-off valve 4 15 is installed on pipeline 23. Waste chlorine pipeline 22 is connected to the main waste chlorine pipeline 6, and a ball valve is installed on waste chlorine pipeline 22 (the ball valve is normally open).

[0016] In this embodiment, a self-regulating valve 17 is also installed on pipeline 12. The self-regulating valve 17 is placed between the check valve 14 and the three-way valve to facilitate stable control of the pressure in the process gas pipeline 12.

[0017] Waste chlorine gas pipeline 218 is connected to the top of the storage tank in use, and waste chlorine gas pipeline 319 is connected to the top of the standby storage tank. Waste chlorine gas pipeline 218 and waste chlorine gas pipeline 319 are respectively connected to the main waste chlorine gas pipeline 6. A shut-off valve 520 is installed on waste chlorine gas pipeline 218 and a pressure relief valve 21 is installed on waste chlorine gas pipeline 319.

[0018] In this embodiment, a pressure transmitter (a commercially available product) is installed on the spare storage tank. The pressure transmitter, shut-off valve 1 8, shut-off valve 2 9, shut-off valve 3 10, shut-off valve 4 15, shut-off valve 5 20 and pressure relief valve 21 are respectively connected to the DCS controller.

[0019] The process flow of this unit is as follows: Liquid chlorine produced in the chlorine liquefaction process enters the in-use storage tank via the liquid chlorine pipeline. The liquid chlorine in the in-use storage tank is then transported to cylinders, tank trucks for filling, or the return pipeline via the liquid chlorine transfer pump 11. The gas phase pressure of different in-use storage tanks is balanced through the chlorine pipeline. When an abnormality occurs in an in-use storage tank or when a tank transfer is required, an action command is issued through the DCS controller to introduce process gas pipeline 12 into the in-use storage tank and transfer the liquid chlorine to the standby storage tank. The specific transfer process is as follows: The DCS controller issues an action command to close the shut-off valve 10 on the main discharge pipeline 3, open the shut-off valve 9 on the standby storage tank discharge pipeline 2 and the shut-off valve 8 on the in-use storage tank discharge pipeline 1, and simultaneously open the shut-off valve 15 on the process gas pipeline 12. The three-way valve 16 closes the waste chlorine gas pipeline 22, keeping pipelines 12 and 2 13 unobstructed. The process gas enters the in-use storage tank through the process gas pipeline 12, and the pressure forces the liquid in the in-use storage tank into the standby storage tank. The liquid enters the standby storage tank, realizing remote tank transfer within the main control.

[0020] During the tank transfer process, the pressure transmitter monitors the internal pressure of the backup tank in real time and transmits the signal to the DCS controller. The DCS controller adjusts the pressure relief valve 21 according to the internal pressure of the backup tank.

[0021] In this embodiment, a one-way valve and a three-way valve are installed on the process gas pipeline to ensure smooth gas flow between the process gas source and the in-use storage tank under the condition of liquid chlorine tank switching; under the condition of non-liquid chlorine storage tank switching, it is avoided that chlorine gas in the normal production process will backflow into the process gas system due to the failure of shut-off valve four, which will affect normal production.

[0022] This invention, in conjunction with process flow settings and DCS control, enables medium switching between in-use and standby storage tanks through process gas pressure. This avoids the drawbacks of requiring on-site confirmation and operation for pump backflow and the need for a liquid chlorine transfer pump to deliver high-pressure liquid chlorine, which could escalate the situation. It simplifies the switching process and reduces the occurrence of accidents.

[0023] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the present invention. All equivalent changes made based on the description and drawings of the present invention are included within the scope of the present invention.

Claims

1. An automatic switching device for liquid chlorine storage tanks, comprising a DCS controller, a used storage tank, a standby storage tank, a discharge pipeline for the used storage tank, a discharge pipeline for the standby storage tank, a main discharge pipeline, a liquid chlorine pipeline, a chlorine gas pipeline, and a waste chlorine gas main pipeline, characterized in that: A shut-off valve 1 is installed on the discharge pipeline of the in-use storage tank, and a shut-off valve 2 is installed on the discharge pipeline of the standby storage tank. The discharge pipelines of the in-use storage tank and the standby storage tank are respectively connected to the main discharge pipeline, and a shut-off valve 3 is installed on the main discharge pipeline. It also includes a process gas pipeline, which is connected to the top of the in-use storage tank, and a shut-off valve 4 is installed on the process gas pipeline. Shut-off valves 1, 2, 3, and 4 are respectively connected to the DCS controller.

2. The automatic switching device for liquid chlorine storage tank according to claim 1, characterized in that: It also includes a three-way valve and a waste chlorine gas pipeline. The process gas pipeline includes pipeline one and pipeline two. Pipeline one, pipeline two and waste gas pipeline one are connected by a three-way valve. A one-way valve is installed on pipeline one, and shut-off valve four is placed on pipeline two. Waste chlorine gas pipeline one is connected to the main waste chlorine gas pipeline.

3. The automatic switching device for liquid chlorine storage tank according to claim 2, characterized in that: A self-regulating valve is also installed on the pipeline, which is located between the check valve and the three-way valve.

4. The automatic switching device for liquid chlorine storage tanks according to claim 1, characterized in that: The main discharge pipeline is connected to the discharge pipelines of the in-use storage tank and the standby storage tank via a three-way valve.

5. The automatic switching device for liquid chlorine storage tanks according to claim 1, characterized in that: Waste chlorine gas pipeline 2 is installed on the top of the storage tank in use, and waste chlorine gas pipeline 3 is installed on the top of the standby storage tank. Waste chlorine gas pipeline 2 and waste chlorine gas pipeline 3 are respectively connected to the main waste chlorine gas pipeline. Waste chlorine gas pipeline 2 is equipped with shut-off valve 5, and waste chlorine gas pipeline 3 is equipped with pressure relief valve. Shut-off valve 5 and pressure relief valve are respectively connected to the DCS controller.

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