Volatile deacidification liquid vapor recovery device and control method thereof

Abstract

The invention relates to the technical field of deacidification liquid vapor recovery, and discloses a volatile deacidification liquid vapor recovery device which comprises a deacidification container, a multi-stage low-temperature cold trap, a low-temperature refrigerating unit, a vacuum unit, a deacidification liquid recovery tank, a tail gas recovery tank, a gas compressor, a medium-temperature cold trap, a medium-temperature refrigerating unit, a pipeline and a control valve. The deacidification container is used for carrying out deacidification treatment on the paper documents; the multi-stage low-temperature cold trap is used for condensing and recycling steam of the deacidification liquid and is connected with the deacidification container through a pipeline, and a heat exchange disc is mounted in the multi-stage low-temperature cold trap; and the low-temperature refrigerating unit is used for providing a circulating refrigerant and refrigerating capacity for the heat exchange coil in the multi-stage low-temperature cold trap. The invention provides a volatile deacidification liquid vapor recovery device and a control method thereof, and condensation recovery of deacidification liquid vapor is realized through a multi-stage low-temperature cold trap device, a medium-temperature cold trap device and a control method matched with the multi-stage low-temperature cold trap device and the medium-temperature cold trap device.

Description

Technical Field

[0001] The invention relates to the technical field of deacidification liquid vapor recovery processing, and in particular to a volatile deacidification liquid vapor recovery device and a control method thereof. Background Art

[0002] At present, there are many technical routes for deacidification of paper documents, including gas phase deacidification, deacidification by immersion in aqueous phase deacidification liquid, deacidification by immersion in anhydrous phase deacidification liquid, and single-page deacidification by manual spraying. However, considering the safety, environmental protection, and deacidification efficiency, the method of deacidification by immersion in organic suspension type anhydrous phase deacidification liquid is adopted. Paper documents have the advantages of not easy deformation, no fading of handwriting, no decrease in paper strength, and good deacidification effect. Volatile deacidification liquid is a chemical substance used to deal with paper acidification problems. It can be used for the protection and restoration of paper cultural relics. Volatile deacidification liquid usually contains ingredients that can neutralize acidic substances in paper, such as diethyl zinc. This substance can react with the acid in the paper and react with cellulose at the same time to inhibit cellulose hydrolysis and deposit zinc oxide on the paper surface, which has a certain corrosion resistance to acid erosion in the environment.

[0003] In the prior art, although the deacidification method using an organic suspension type anhydrous phase deacidification solution has high deacidification efficiency and has prospects for large-scale application, the deacidification cost still needs to be controlled within a reasonable range to achieve large-scale application. The cost of the deacidification solution accounts for the bulk of the deacidification cost. If it cannot be effectively recycled and reused, it will limit its wide application in reality.

[0004] In order to solve the above problems, the present application proposes a volatile deacidification liquid vapor recovery device and a control method thereof. Summary of the invention

[0005] Based on the technical problems existing in the background technology, the present invention proposes a volatile deacidification liquid vapor recovery device and a control method thereof.

[0006] The present invention provides a volatile deacidification liquid vapor recovery device, comprising: a deacidification container, a multi-stage low-temperature cold trap, a low-temperature refrigeration unit, a vacuum unit, a deacidification liquid recovery tank, a tail gas recovery tank, a gas compressor, a medium-temperature cold trap, a medium-temperature refrigeration unit, pipelines and control valves; Deacidification container, used for deacidification of paper documents; The multi-stage low-temperature cold trap is used for condensation and recovery of deacidification liquid vapor, and is connected to the deacidification container through a pipeline. A heat exchange plate is installed in the multi-stage low-temperature cold trap; A low temperature refrigeration unit is used to provide circulating refrigerant and its cooling capacity for the heat exchange coils in the multi-stage low temperature cold trap; A vacuum unit, used for evacuating the deacidification container, connected with the deacidification container and the multi-stage low-temperature cold trap through pipelines; The deacidification liquid recovery tank is used to store the liquid deacidification liquid recovered by condensation of the multi-stage low-temperature cold trap, and is connected to the multi-stage low-temperature cold trap through multiple pipelines; The tail gas recovery tank is used to buffer the gas discharged from the vacuum unit and is connected to the vacuum unit through a pipeline; A gas compressor is used to pressurize the gas in the tail gas recovery tank, and is connected to the tail gas recovery tank through a pipeline. The gas compressor is also connected to the medium-temperature cold trap through a pipeline; The medium temperature cold trap is used to further condense and recover the deacidified liquid vapor mixed in the tail gas recovery tank, and is connected to the tail gas recovery tank through a pipeline. The medium temperature cold trap is also connected to the deacidified liquid recovery tank through a pipeline; A medium temperature refrigeration unit is used to provide circulating refrigerant and its cooling capacity for the heat exchange coil in the medium temperature cold trap; Pipes and control valves are used to connect various devices to form a closed system, and control valves are used to control the flow of gas and liquid during the deacidification process.

[0007] As a further optimization scheme of the present invention, the control valve components include valve V1, valve V2, valve V3, valve V4, valve V5 and valve V6. Valve V1 is installed on the pipeline between the deacidification container and the multi-stage low-temperature cold trap, valve V2, valve V3 and valve V4 are respectively installed on multiple pipelines between the multi-stage low-temperature cold trap and the deacidification liquid recovery tank, valve V5 is installed on the pipeline between the vacuum unit and the tail gas recovery tank, and valve V6 is installed on the pipeline between the deacidification liquid recovery tank and the medium-temperature cold trap.

[0008] As a further optimization solution of the present invention, it also includes a control system; The control system includes a pressure sensor and a temperature sensor, a deacidification liquid vapor concentration sensor, and a vacuum unit, a low-temperature refrigeration unit, a medium-temperature refrigeration unit, a gas compressor and the switch status of each control valve on the pipeline to achieve full automatic control of the deacidification liquid recovery process.

[0009] As a further optimization scheme of the present invention, the multi-stage low-temperature cold trap is designed with a three-stage cold trap, and the low temperature below -50°C of the cold trap is used to condense and recover the deacidification liquid vapor.

[0010] As a further optimization scheme of the present invention, the deacidification liquid is an anhydrous liquid phase deacidification liquid, which is mainly composed of a highly volatile organic solvent and nano-scale alkaline deacidification particles.

[0011] As a further optimization scheme of the present invention, the control system can control the opening and closing of the vacuum unit, the low-temperature refrigeration unit, the medium-temperature refrigeration unit, the gas compressor and each control valve component according to the readings of the pressure sensors and temperature sensors in the multi-stage low-temperature cold trap and the medium-temperature cold trap, and the deacidification liquid vapor concentration sensor in the tail gas recovery tank.

[0012] As a further optimization scheme of the present invention, the tail gas recovery tank serves as a buffer between the multi-stage low-temperature cold trap and the medium-temperature cold trap, so that the deacidification container, multi-stage low-temperature cold trap, vacuum unit, tail gas recovery tank, gas compressor, and medium-temperature cold trap are connected in series through pipelines to form a closed system.

[0013] As a further optimization scheme of the present invention, the vacuum unit and the low-temperature refrigeration unit corresponding to the multi-stage low-temperature cold trap automatically shut down after the deacidification liquid vapor recovery process is completed, and the valve V5 between the vacuum unit and the tail gas recovery tank is closed.

[0014] As a further optimization scheme of the present invention, the control system automatically stops the operation of the medium-temperature refrigeration unit corresponding to the gas compressor and the medium-temperature cold trap when the deacidification liquid vapor concentration sensor in the tail gas recovery tank detects that the vapor concentration is lower than a preset value.

[0015] A control method for a volatile deacidification liquid vapor recovery device comprises the following steps: Step 1: First, before starting to recover the deacidification liquid vapor, start the low-temperature refrigeration unit and the medium-temperature refrigeration unit in advance to pre-cool the multi-stage low-temperature cold trap and the medium-temperature cold trap; Step 2: When the multi-stage low-temperature cold trap has been precooled to temperature T1 and the medium-temperature cold trap has been precooled to temperature T2, open the valve V1 between the deacidification container and the multi-stage low-temperature cold trap, open the valve V5 between the vacuum unit and the tail gas recovery tank, and start the vacuum unit to start recovering the deacidification liquid vapor; Step 3: In the deacidification vapor recovery process, the vapor undergoes heat exchange with the refrigeration coil in the multi-stage low-temperature cold trap and condenses into liquid. The liquid deacidification liquid is collected at the bottom of the multi-stage low-temperature cold trap and then flows into the deacidification liquid recovery tank through a pipeline; Step 4: Valves V2, V3, and V4 are arranged between the multi-stage low-temperature cold trap and the deacidification liquid recovery tank. The valves V2, V3, and V4 are controlled by the control system to open at a fixed time to return the condensed liquid deacidification liquid to the deacidification liquid recovery tank; Step 5: As the vacuum unit works, when the pressure in the tail gas recovery tank rises to P2, the gas compressor is started to pressurize the gas in the tail gas recovery tank, and the pressurized gas is discharged into the medium-temperature cold trap to further condense and recover the deacidified liquid vapor in the tail gas; Step 6: A valve V6 is provided between the medium-temperature cold trap and the deacidification liquid recovery tank. The valve V6 is controlled by the control system to open at a fixed time to return the liquid deacidification liquid condensed in the medium-temperature cold trap to the deacidification liquid recovery tank; Step 7: In the above deacidification liquid vapor recovery process, when the pressure in the multi-stage low-temperature cold trap drops below P1 for 20 minutes, the vacuum unit and the low-temperature refrigeration unit corresponding to the multi-stage low-temperature cold trap are shut down, and the valve V5 between the vacuum unit and the tail gas recovery tank is closed; Step 8: When the deacidification liquid vapor concentration sensor in the tail gas recovery tank detects that the vapor concentration is lower than N1, the medium-temperature refrigeration unit corresponding to the gas compressor and the medium-temperature cold trap stops working.

[0016] The above technical solution of the present invention has the following beneficial technical effects: 1. Realize the recycling of deacidification liquid and reduce the cost of deacidification; 2. Through the multi-stage low-temperature cold trap, medium-temperature cold trap device and its coordinated control method, the condensation recovery of the deacidification liquid vapor is realized; 3. The tail gas recovery tank is designed as a buffer between the multi-stage low-temperature cold trap and the medium-temperature cold trap, so that the deacidified liquid can be recycled in the device; 4. It reduces the cost of batch deacidification of paper books and documents, making large-scale application possible. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The schematic diagram of a volatile deacidification liquid vapor recovery device proposed by the present invention.

[0018] Figure 2 The present invention provides a flow chart of a control method for a volatile deacidification liquid vapor recovery device. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings. It should be understood that these descriptions are only exemplary and are not intended to limit the scope of the present invention. In addition, in the following description, the description of well-known structures and technologies is omitted to avoid unnecessary confusion of the concept of the present invention.

[0020] like Figure 1 and Figure 2 As shown, a volatile deacidification liquid vapor recovery device proposed by the present invention comprises: a deacidification container, a multi-stage low-temperature cold trap, a low-temperature refrigeration unit, a vacuum unit, a deacidification liquid recovery tank, a tail gas recovery tank, a gas compressor, a medium-temperature cold trap, a medium-temperature refrigeration unit, pipelines and control valves; Deacidification container, used for deacidification of paper documents; The multi-stage low-temperature cold trap is used for condensation and recovery of deacidification liquid vapor, and is connected to the deacidification container through a pipeline. A heat exchange plate is installed in the multi-stage low-temperature cold trap; A low temperature refrigeration unit is used to provide circulating refrigerant and its cooling capacity for the heat exchange coils in the multi-stage low temperature cold trap; A vacuum unit, used for evacuating the deacidification container, connected with the deacidification container and the multi-stage low-temperature cold trap through pipelines; The deacidification liquid recovery tank is used to store the liquid deacidification liquid recovered by condensation of the multi-stage low-temperature cold trap, and is connected to the multi-stage low-temperature cold trap through multiple pipelines; The tail gas recovery tank is used to buffer the gas discharged from the vacuum unit and is connected to the vacuum unit through a pipeline; A gas compressor is used to pressurize the gas in the tail gas recovery tank, and is connected to the tail gas recovery tank through a pipeline. The gas compressor is also connected to the medium-temperature cold trap through a pipeline; The medium temperature cold trap is used to further condense and recover the deacidified liquid vapor mixed in the tail gas recovery tank, and is connected to the tail gas recovery tank through a pipeline. The medium temperature cold trap is also connected to the deacidified liquid recovery tank through a pipeline; A medium temperature refrigeration unit is used to provide circulating refrigerant and its cooling capacity for the heat exchange coil in the medium temperature cold trap; Pipes and control valves are used to connect various devices to form a closed system, and control valves are used to control the flow of gas and liquid during the deacidification process.

[0021] In a specific embodiment, the control valve components include valve V1, valve V2, valve V3, valve V4, valve V5 and valve V6. Valve V1 is installed on the pipeline between the deacidification container and the multi-stage low-temperature cold trap, valve V2, valve V3 and valve V4 are respectively installed on multiple pipelines between the multi-stage low-temperature cold trap and the deacidification liquid recovery tank, valve V5 is installed on the pipeline between the vacuum unit and the tail gas recovery tank, and valve V6 is installed on the pipeline between the deacidification liquid recovery tank and the medium-temperature cold trap.

[0022] In a specific embodiment, a control system is also included; The control system includes a pressure sensor and a temperature sensor, a deacidification liquid vapor concentration sensor, and a vacuum unit, a low-temperature refrigeration unit, a medium-temperature refrigeration unit, a gas compressor and the switch status of each control valve on the pipeline to achieve full automatic control of the deacidification liquid recovery process.

[0023] In a specific embodiment, the multi-stage low-temperature cold trap is designed with a three-stage cold trap, and the low temperature below -50°C of the cold trap is used to condense and recover the deacidification liquid vapor.

[0024] In a specific embodiment, the deacidification liquid is an anhydrous liquid phase deacidification liquid, which is mainly composed of a highly volatile organic solvent and nano-scale alkaline deacidification particles.

[0025] In a specific embodiment, the control system can control the opening and closing of the vacuum unit, the low-temperature refrigeration unit, the medium-temperature refrigeration unit, the gas compressor and each control valve component according to the readings of the pressure sensors and temperature sensors in the multi-stage low-temperature cold trap and the medium-temperature cold trap, and the deacidification liquid vapor concentration sensor in the tail gas recovery tank.

[0026] In a specific embodiment, the tail gas recovery tank serves as a buffer between the multi-stage low-temperature cold trap and the medium-temperature cold trap, so that the deacidification container, multi-stage low-temperature cold trap, vacuum unit, tail gas recovery tank, gas compressor, and medium-temperature cold trap are connected in series through pipelines to form a closed system.

[0027] In a specific embodiment, the vacuum unit and the low-temperature refrigeration unit corresponding to the multi-stage low-temperature cold trap are automatically shut down after the deacidification liquid vapor recovery process is completed, and the valve V5 between the vacuum unit and the tail gas recovery tank is closed.

[0028] In a specific embodiment, when the deacidification liquid vapor concentration sensor in the tail gas recovery tank detects that the vapor concentration is lower than a preset value, the control system automatically stops the operation of the gas compressor and the medium-temperature refrigeration unit corresponding to the medium-temperature cold trap.

[0029] A control method for a volatile deacidification liquid vapor recovery device comprises the following steps: Step 1: First, before starting to recover the deacidification liquid vapor, start the low-temperature refrigeration unit and the medium-temperature refrigeration unit in advance to pre-cool the multi-stage low-temperature cold trap and the medium-temperature cold trap; Step 2: When the multi-stage low-temperature cold trap has been precooled to temperature T1 and the medium-temperature cold trap has been precooled to temperature T2, open the valve V1 between the deacidification container and the multi-stage low-temperature cold trap, open the valve V5 between the vacuum unit and the tail gas recovery tank, and start the vacuum unit to start recovering the deacidification liquid vapor; Step 3: In the deacidification vapor recovery process, the vapor undergoes heat exchange with the refrigeration coil in the multi-stage low-temperature cold trap and condenses into liquid. The liquid deacidification liquid is collected at the bottom of the multi-stage low-temperature cold trap and then flows into the deacidification liquid recovery tank through a pipeline; Step 4: Valves V2, V3, and V4 are arranged between the multi-stage low-temperature cold trap and the deacidification liquid recovery tank. The valves V2, V3, and V4 are controlled by the control system to open at a fixed time to return the condensed liquid deacidification liquid to the deacidification liquid recovery tank; Step 5: As the vacuum unit works, when the pressure in the tail gas recovery tank rises to P2, the gas compressor is started to pressurize the gas in the tail gas recovery tank, and the pressurized gas is discharged into the medium-temperature cold trap to further condense and recover the deacidified liquid vapor in the tail gas; Step 6: A valve V6 is provided between the medium-temperature cold trap and the deacidification liquid recovery tank. The valve V6 is controlled by the control system to open at a fixed time to return the liquid deacidification liquid condensed in the medium-temperature cold trap to the deacidification liquid recovery tank; Step 7: In the above deacidification liquid vapor recovery process, when the pressure in the multi-stage low-temperature cold trap drops below P1 for 20 minutes, the vacuum unit and the low-temperature refrigeration unit corresponding to the multi-stage low-temperature cold trap are shut down, and the valve V5 between the vacuum unit and the tail gas recovery tank is closed; Step 8: When the deacidification liquid vapor concentration sensor in the tail gas recovery tank detects that the vapor concentration is lower than N1, the medium-temperature refrigeration unit corresponding to the gas compressor and the medium-temperature cold trap stops working.

[0030] It should be understood that the above specific embodiments of the present invention are only used to illustrate or explain the principles of the present invention, and do not constitute a limitation of the present invention. Therefore, any modifications, equivalent substitutions, improvements, etc. made without departing from the spirit and scope of the present invention should be included in the protection scope of the present invention. In addition, the appended claims of the present invention are intended to cover all changes and modifications that fall within the scope and boundaries of the appended claims, or the equivalent forms of such scope and boundaries.

Claims

1. A volatile deacidification liquid vapor recovery device, characterized in that: include: Deacidification container, multi-stage low-temperature cold trap, low-temperature refrigeration unit, vacuum unit, deacidification liquid recovery tank, tail gas recovery tank, gas compressor, medium-temperature cold trap, medium-temperature refrigeration unit, pipelines and control valves; Deacidification container, used for deacidification of paper documents; The multi-stage low-temperature cold trap is used for condensation and recovery of deacidification liquid vapor, and is connected to the deacidification container through a pipeline. A heat exchange plate is installed in the multi-stage low-temperature cold trap; A low temperature refrigeration unit is used to provide circulating refrigerant and its cooling capacity for the heat exchange coils in the multi-stage low temperature cold trap; A vacuum unit, used for evacuating the deacidification container, connected with the deacidification container and the multi-stage low-temperature cold trap through pipelines; The deacidification liquid recovery tank is used to store the liquid deacidification liquid recovered by condensation of the multi-stage low-temperature cold trap, and is connected to the multi-stage low-temperature cold trap through multiple pipelines; The tail gas recovery tank is used to buffer the gas discharged from the vacuum unit and is connected to the vacuum unit through a pipeline; A gas compressor is used to pressurize the gas in the tail gas recovery tank, and is connected to the tail gas recovery tank through a pipeline. The gas compressor is also connected to the medium-temperature cold trap through a pipeline; The medium temperature cold trap is used to further condense and recover the deacidified liquid vapor mixed in the tail gas recovery tank, and is connected to the tail gas recovery tank through a pipeline. The medium temperature cold trap is also connected to the deacidified liquid recovery tank through a pipeline; A medium temperature refrigeration unit is used to provide circulating refrigerant and its cooling capacity for the heat exchange coil in the medium temperature cold trap; Pipes and control valves are used to connect various devices to form a closed system, and control valves are used to control the flow of gas and liquid during the deacidification process.

2. A volatile deacidification liquid vapor recovery device according to claim 1, characterized in that: The control valve components include valve V1, valve V2, valve V3, valve V4, valve V5 and valve V6. Valve V1 is installed on the pipeline between the deacidification container and the multi-stage low-temperature cold trap. Valves V2, valve V3 and valve V4 are respectively installed on multiple pipelines between the multi-stage low-temperature cold trap and the deacidification liquid recovery tank. Valve V5 is installed on the pipeline between the vacuum unit and the tail gas recovery tank. Valve V6 is installed on the pipeline between the deacidification liquid recovery tank and the medium-temperature cold trap.

3. A volatile deacidification liquid vapor recovery device according to claim 2, characterized in that: Also includes control systems; The control system includes a pressure sensor and a temperature sensor, a deacidification liquid vapor concentration sensor, and a vacuum unit, a low-temperature refrigeration unit, a medium-temperature refrigeration unit, a gas compressor and the switch status of each control valve on the pipeline to achieve full automatic control of the deacidification liquid recovery process.

4. A volatile deacidification liquid vapor recovery device according to claim 3, characterized in that: The multi-stage low-temperature cold trap is designed with a three-stage cold trap, and the low temperature below -50°C of the cold trap is used to condense and recover the deacidification liquid vapor.

5. A volatile deacidification liquid vapor recovery device according to claim 4, characterized in that: The deacidification liquid is an anhydrous liquid phase deacidification liquid, which is mainly composed of a highly volatile organic solvent and nanometer-level alkaline deacidification particles.

6. A volatile deacidification liquid vapor recovery device according to claim 5, characterized in that: The control system can control the opening and closing of the vacuum unit, the low-temperature refrigeration unit, the medium-temperature refrigeration unit, the gas compressor and various control valves according to the readings of the pressure sensors and temperature sensors in the multi-stage low-temperature cold trap and the medium-temperature cold trap and the deacidification liquid vapor concentration sensor in the tail gas recovery tank.

7. A volatile deacidification liquid vapor recovery device according to claim 6, characterized in that: The tail gas recovery tank serves as a buffer between the multi-stage low-temperature cold trap and the medium-temperature cold trap, so that the deacidification container, the multi-stage low-temperature cold trap, the vacuum unit, the tail gas recovery tank, the gas compressor, and the medium-temperature cold trap are connected in series through pipelines to form a closed system.

8. A volatile deacidification liquid vapor recovery device according to claim 7, characterized in that: The vacuum unit and the low-temperature refrigeration unit corresponding to the multi-stage low-temperature cold trap automatically shut down after the deacidification liquid vapor recovery process is completed, and the valve V5 between the vacuum unit and the tail gas recovery tank is closed.

9. A volatile deacidification liquid vapor recovery device according to claim 8, characterized in that: The control system automatically stops the operation of the medium-temperature refrigeration unit corresponding to the gas compressor and the medium-temperature cold trap when the deacidification liquid vapor concentration sensor in the tail gas recovery tank detects that the vapor concentration is lower than a preset value.

10. A control method for a volatile deacidification liquid vapor recovery device, characterized in that: The following steps are involved: Step 1: First, before starting to recover the deacidification liquid vapor, start the low-temperature refrigeration unit and the medium-temperature refrigeration unit in advance to pre-cool the multi-stage low-temperature cold trap and the medium-temperature cold trap; Step 2: When the multi-stage low-temperature cold trap has been precooled to temperature T1 and the medium-temperature cold trap has been precooled to temperature T2, open the valve V1 between the deacidification container and the multi-stage low-temperature cold trap, open the valve V5 between the vacuum unit and the tail gas recovery tank, and start the vacuum unit to start recovering the deacidification liquid vapor; Step 3: In the deacidification vapor recovery process, the vapor undergoes heat exchange with the refrigeration coil in the multi-stage low-temperature cold trap and condenses into liquid. The liquid deacidification liquid is collected at the bottom of the multi-stage low-temperature cold trap and then flows into the deacidification liquid recovery tank through a pipeline; Step 4: Valves V2, V3, and V4 are arranged between the multi-stage low-temperature cold trap and the deacidification liquid recovery tank. The valves V2, V3, and V4 are controlled by the control system to open at a fixed time to return the condensed liquid deacidification liquid to the deacidification liquid recovery tank; Step 5: As the vacuum unit works, when the pressure in the tail gas recovery tank rises to P2, the gas compressor is started to pressurize the gas in the tail gas recovery tank, and the pressurized gas is discharged into the medium-temperature cold trap to further condense and recover the deacidified liquid vapor in the tail gas; Step 6: A valve V6 is provided between the medium-temperature cold trap and the deacidification liquid recovery tank. The valve V6 is controlled by the control system to open at a fixed time to return the liquid deacidification liquid condensed in the medium-temperature cold trap to the deacidification liquid recovery tank; Step 7: In the above deacidification liquid vapor recovery process, when the pressure in the multi-stage low-temperature cold trap drops below P1 for 20 minutes, the vacuum unit and the low-temperature refrigeration unit corresponding to the multi-stage low-temperature cold trap are shut down, and the valve V5 between the vacuum unit and the tail gas recovery tank is closed; Step 8: When the deacidification liquid vapor concentration sensor in the tail gas recovery tank detects that the vapor concentration is lower than N1, the medium-temperature refrigeration unit corresponding to the gas compressor and the medium-temperature cold trap stops working.

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