Liquid chlorine tail gas recovery equipment and process

Abstract

The invention provides liquid chlorine tail gas recovery equipment and a liquid chlorine tail gas recovery process. The liquid chlorine tail gas recovery equipment comprises liquid chlorine filling equipment and a chlorine gas compressor communicated with the liquid chlorine filling equipment through a tail gas discharge pipe. According to the liquid chlorine tail gas recovery equipment and process, communication of a first liquid discharge pipe, a second liquid discharge pipe and a third liquid discharge pipe can be cut off through an electromagnetic valve, so that liquefied liquid chlorine can be stored in a cooling device, and gas can be isolated to the outer sides of the liquid discharge pipes through the liquid chlorine; the liquid pressure generated by the liquid chlorine can be detected through a pressure sensor, and once the pressure is larger than a set value, an electromagnetic valve can be controlled to be started through a controller, so that the liquid chlorine in the cooling device can be conveyed into a liquid nitrogen storage tank through a collecting pipe to be stored; the liquid level of liquid chlorine is ensured not to touch the snake-shaped heat exchange tube, tail gas blockage is avoided, other gases contained in the liquid chlorine tail gas are not easy to enter the liquid nitrogen storage tank by adopting the structure, and the purity of the liquid chlorine is improved.

Description

Technical Field

[0001] The invention relates to the technical field of liquid chlorine tail gas recovery, and specifically discloses liquid chlorine tail gas recovery equipment and process. Background Art

[0002] During the production of liquid chlorine, the filling process of liquid chlorine will produce some exhaust gas, the main component of which is chlorine. In order to treat the chlorine generated during the packaging process and make it discharged in a qualified manner, the liquid chlorine needs to be subjected to exhaust gas recovery treatment.

[0003] Some existing tail gas recovery equipment uses a chlorine compressor to compress the tail gas, change the boiling point of the chlorine, and then cool it down in a cooling device to liquefy it to form liquid chlorine, and collect the liquid chlorine in a liquid nitrogen storage tank. During this process, other gases contained in the liquid chlorine tail gas easily enter the liquid nitrogen storage tank, which reduces the purity of the liquid chlorine. At the same time, the liquid chlorine tail gas stays in the cooling device for a short time, so that the cooling device cannot effectively cool the compressed chlorine. Summary of the invention

[0004] In view of the above-mentioned defects or deficiencies in the prior art, the present application aims to provide a liquid chlorine tail gas recovery device and process, including a liquid chlorine filling device, a chlorine compressor connected to the liquid chlorine filling device through a tail gas exhaust pipe, and a cooling device connected to the chlorine compressor through an air inlet pipe, wherein a serpentine heat exchange tube is arranged inside the cooling device, and the top end of the serpentine heat exchange tube extending outside the cooling device is connected to a liquid inlet pipe and a reflux pipe, a partition located inside the serpentine heat exchange tube is arranged on the inner side of the cooling device, and an exhaust bin and a fixedly installed heat exchanger between the chlorine compressor and the cooling device are respectively arranged on the side away from the air inlet pipe. A controller for electrical connection, the interior of one side of the exhaust bin is connected with an exhaust pipe, and a cleaning structure connected with the cooling device is installed on the top of the exhaust bin, the exhaust pipe extends to the outside of one end of the exhaust pipe inside the exhaust bin and is connected with a gas-liquid separation mechanism, the interior of the bottom of the cooling device is connected with a first drain pipe, a second drain pipe and a third drain pipe, the bottom ends of the first drain pipe, the second drain pipe and the third drain pipe are commonly connected with a manifold, the manifold is connected with a liquid nitrogen storage tank, and the middle parts of the first drain pipe, the second drain pipe and the third drain pipe are all provided with solenoid valves electrically connected with the controller.

[0005] Preferably, the bottom of the cooling device located on one side of the first drain pipe, the second drain pipe and the third drain pipe is provided with a pressure sensor electrically connected to the controller.

[0006] Preferably, a gas flow meter electrically connected to the controller is provided on the outer side of one end of the exhaust pipe extending out of the exhaust chamber.

[0007] Preferably, the cleaning structure includes a first air pipe connected to one side of the top of the cooling device and a second air pipe connected to one side of the top of the exhaust bin. The outer sides of the top ends of the first air pipe and the second air pipe are commonly connected to a vacuum fan fixedly installed above the exhaust bin. The outer sides of the first air pipe and the second air pipe are respectively provided with a first one-way valve and a second one-way valve. The second air pipe extends to the outer side of the bottom end inside the exhaust bin and is connected to a nozzle.

[0008] Preferably, the exhaust holes inside the nozzle are arranged in a rectangular shape.

[0009] Preferably, the gas-liquid separation mechanism comprises an adapter connected to the outside of the exhaust pipe and having an inclined end face on one side, a fixing ring is sleeved on the inner side of the adapter, and the inner thread of the adapter is sleeved with a fixing ring located on the outside of the gas-liquid separation membrane.

[0010] Preferably, the liquid chlorine tail gas recovery equipment comprises the following process steps: S1, the condenser is started by the controller 11, and the cooling water is transported to the inside of the serpentine heat exchange tube 6 through the liquid inlet pipe 7, and the serpentine heat exchange tube 6 is cooled by the cooling water and then refluxed to the inside of the condenser through the reflux pipe 8 for recycling; S2, controlling the chlorine compressor 3 to drive, while the chlorine compressor 3 is driven, the liquid chlorine tail gas generated inside the liquid chlorine filling equipment 1 is compressed through the tail gas exhaust pipe 2 and then transported to the inside of the cooling device 5 through the air intake pipe 4; S3, the chlorine in the liquid chlorine tail gas is cooled and gradually liquefied into liquid chlorine after contacting the serpentine heat exchange tube 6, and the formed liquid chlorine drips into the inside of the liquid chlorine storage bin for collection, and the remaining unliquefied gas is transported to the inside of the exhaust bin 10 along the S-shaped channel. With the continuous transportation of the liquid chlorine tail gas inside the cooling device 5, the remaining gas inside the exhaust bin 10 passes through the gas-liquid separation membrane 142 and the adapter 141 and is discharged through the exhaust pipe 12; S4, when the pressure sensor 21 detects that the pressure generated by the liquid chlorine is greater than the set value, the controller 11 controls the solenoid valve 20 to start, and the passage between the first drain pipe 15, the second drain pipe 16 or the third drain pipe 17 and the manifold 18 is opened by driving the solenoid valve 20. At this time, the liquid chlorine collected in the liquid chlorine storage bin is discharged to the interior of the liquid nitrogen storage tank 19 through the first drain pipe 15, the second drain pipe 16 or the third drain pipe 17 and the manifold 18 for collection and storage. When the pressure sensor 21 detects that the pressure generated by the liquid chlorine is less than the set value, the controller 11 controls the solenoid valve 20 to close, and the passage between the first drain pipe 15, the second drain pipe 16 or the third drain pipe 17 and the manifold 18 is cut off; S5. When the gas flow meter 22 detects that the gas flow discharged from the exhaust pipe 12 is less than the set value, the controller 11 controls the vacuum pump 133 to be driven. While the vacuum pump 133 is driven, the remaining unliquefied gas in the cooling device 5 is extracted through the first air pipe 131. After extraction, the gas is blown to the surface of the gas-liquid separation membrane 142 through the exhaust hole inside the nozzle 136 through the second air pipe 132, and the liquid attached to the surface of the gas-liquid separation membrane 142 is cleaned by the generated airflow. Beneficial Effects

[0011] 1. The liquid chlorine tail gas recovery equipment and process can cut off the connection between the first drain pipe, the second drain pipe and the third drain pipe through the solenoid valve, so that the liquefied liquid chlorine can be stored inside the cooling device, and then the gas can be isolated to the outside of the drain pipe through the liquid chlorine, and the liquid pressure generated by the liquid chlorine can be detected by the pressure sensor. Once the pressure is greater than the set value, the solenoid valve can be controlled by the controller to start, so that the liquid chlorine inside the cooling device can be transported to the inside of the liquid nitrogen storage tank through the manifold for storage, ensuring that the liquid chlorine level will not touch the serpentine heat exchange tube to avoid tail gas blockage. This structure makes it difficult for other gases contained in the liquid chlorine tail gas to enter the liquid nitrogen storage tank, thereby improving the purity of the liquid chlorine.

[0012] 2. The liquid chlorine tail gas recovery equipment and process can make the liquid chlorine tail gas flow along an S-shaped route through the partition and reduce the flow rate of the liquid chlorine tail gas, so that the compressed liquid chlorine tail gas can fully contact with the serpentine heat exchange tube, ensuring that the cooling device can effectively cool the compressed chlorine gas. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Other features, objects and advantages of the present application will become more apparent by reading the detailed description of non-limiting embodiments made with reference to the following drawings: Figure 1 It is a schematic diagram of the structure of the present invention; Figure 2 A schematic diagram of the partition distribution of the structure of the present invention; Figure 3 for Figure 1 A magnified schematic diagram of the structure at center A; Figure 4 It is a bottom schematic diagram of the nozzle of the present invention; Figure 5 Schematic diagram of the gas-liquid separation mechanism of the present invention.

[0014] In the figure: 1. liquid chlorine filling equipment; 2. tail gas exhaust pipe; 3. chlorine compressor; 4. air inlet pipe; 5. cooling device; 6. serpentine heat exchange tube; 7. liquid inlet pipe; 8. reflux pipe; 9. partition; 10. exhaust bin; 11. controller; 12. exhaust pipe; 13. cleaning structure; 131. first air pipe; 132. second air pipe; 133. vacuum pump; 134. first non-return valve; 135. second non-return valve; 136. nozzle; 14. gas-liquid separation mechanism; 141. adapter; 142. gas-liquid separation membrane; 143. fixing ring; 15. first liquid discharge pipe; 16. second liquid discharge pipe; 17. third liquid discharge pipe; 18. conduit; 19. liquid nitrogen storage tank; 20. solenoid valve; 21. pressure sensor; 22. gas flow meter. DETAILED DESCRIPTION

[0015] The present application will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the relevant inventions, rather than to limit the inventions. It is also necessary to explain that, for ease of description, only the parts related to the invention are shown in the accompanying drawings.

[0016] The accompanying drawings in the embodiments of the present invention: different types of section lines in the drawings are not marked according to national standards, nor do they impose requirements on the materials of the components. Instead, they are used to distinguish the cross-sectional views of the components in the drawings.

[0017] See also Figure 1-5A liquid chlorine tail gas recovery device and process, comprising a liquid chlorine filling device 1, a chlorine compressor 3 connected to the liquid chlorine filling device 1 through a tail gas exhaust pipe 2, and a cooling device 5 connected to the chlorine compressor 3 through an air intake pipe 4, wherein a serpentine heat exchange pipe 6 is arranged inside the cooling device 5, and the top end of the serpentine heat exchange pipe 6 extending outside the cooling device 5 is connected to a liquid inlet pipe 7 and a reflux pipe 8, and the liquid inlet pipe 7 and the reflux pipe 8 are jointly connected to a condenser electrically connected to a controller 11, and the condenser 11 is electrically connected to the controller 11 through the cooler Cooling water can be transported to the inside of the serpentine heat exchange tube 6 through the liquid inlet pipe 7 to cool the serpentine heat exchange tube 6. A partition 9 located on the inside of the serpentine heat exchange tube 6 is provided on the inner side of the cooling device 5. The inner side of the cooling device 5 can be divided into a plurality of continuous S-shaped channels through the partition 9, and the inner side of the cooling device 5 is separately divided into liquid chlorine storage bins respectively connected to the first drain pipe 15, the second drain pipe 16 and the third drain pipe 17, to ensure that the liquefied liquid chlorine can be stored in each liquid chlorine storage bin. An exhaust bin 10 and a controller 11 fixedly installed and electrically connected to the chlorine compressor 3 are respectively provided on the side of the cooling device 5 away from the air inlet pipe 4. An exhaust pipe 12 is connected to the inside of one side of the exhaust bin 10. The gas transported to the inside of the exhaust bin 10 can be discharged to the outside of the cooling device 5 through the exhaust pipe 12. A cleaning structure 13 connected to the cooling device 5 is installed on the top of the exhaust bin 10. The exhaust pipe 12 extends to the outside of one end of the exhaust bin 10 and is connected to The gas-liquid separation mechanism 14 and the interior of the bottom of the cooling device 5 are connected with a first drain pipe 15, a second drain pipe 16 and a third drain pipe 17, the bottom ends of the first drain pipe 15, the second drain pipe 16 and the third drain pipe 17 are commonly connected with a conduit 18, the conduit 18 is connected with a liquid nitrogen storage tank 19, and the middle parts of the first drain pipe 15, the second drain pipe 16 and the third drain pipe 17 are all provided with solenoid valves 20 electrically connected to the controller 11, and the solenoid valves 20 are in a closed state when not powered.

[0018] Among them, the cooling device 5 is provided with a pressure sensor 21 electrically connected to the controller 11 at the bottom of the first drain pipe 15, the second drain pipe 16 and the third drain pipe 17. The pressure sensor 21 can detect the pressure of the liquid chlorine inside each liquid chlorine storage bin separately to ensure that the liquid chlorine level inside each liquid chlorine storage bin will not touch the serpentine heat exchange tube 6, so that the liquid chlorine tail gas can be connected along the S-shaped channel.

[0019] Among them, a gas flow meter 22 electrically connected to the controller 11 is provided on the outer side of one end of the exhaust pipe 12 extending out of the exhaust bin 10. The gas flow meter 22 can detect the gas flow discharged from the inside of the exhaust pipe 12. Once the gas flow meter 22 detects that the gas flow is less than the set value, it is determined that the gas-liquid separation membrane 142 is blocked. At this time, the controller 11 can control the vacuum pump 133 to drive it, so that the gas discharged through the nozzle 136 blows the surface of the gas-liquid separation membrane 142 to blow off the liquid accumulated on the surface of the gas-liquid separation membrane 142, thereby realizing automatic cleaning of the surface of the gas-liquid separation membrane 142 and avoiding blockage of the gas-liquid separation membrane 142.

[0020] The cleaning structure 13 includes a first air pipe 131 connected to one side of the top of the cooling device 5 and a second air pipe 132 connected to one side of the top of the exhaust bin 10. The outer sides of the tops of the first air pipe 131 and the second air pipe 132 are connected to a vacuum pump 133 fixedly installed above the exhaust bin 10. The outer sides of the first air pipe 131 and the second air pipe 132 are respectively provided with a first one-way valve 134 and a second one-way valve 135. The first one-way valve 134 and the second one-way valve 135 make the first air pipe 131 and the second one-way valve 135 The gas inside the air pipe 132 can only flow in one direction to prevent the exhaust gas inside the cooling device 5 from leaking out. The second air pipe 132 extends to the bottom end of the inner side of the exhaust bin 10 and is connected to a nozzle 136 on the outer side. The vacuum pump 133 drives the gas inside the cooling device 5 through the first air pipe 131, and transports the gas to the inside of the nozzle 136 through the second air pipe 132, while blowing air on the surface of the gas-liquid separation membrane 142, thereby cleaning the surface of the gas-liquid separation membrane 142 through the flow of air.

[0021] The exhaust holes inside the nozzle 136 are arranged in a rectangular shape, and the gas can be evenly blown to the surface of the gas-liquid separation membrane 142 through the rectangular arrangement of the exhaust holes, thereby ensuring that the generated airflow can effectively clean the surface of the gas-liquid separation membrane 142.

[0022] Among them, the gas-liquid separation mechanism 14 includes an adapter 141 which is connected to the outside of the exhaust pipe 12 and has an inclined end face on one side. By inclining the end face on one side of the adapter 141, the gas discharged from the inside of the nozzle 136 can be blown to the surface of the gas-liquid separation membrane 142. The inner side of the adapter 141 is provided with a fixing ring 143, and the inner side thread of the adapter 141 is provided with a fixing ring 143 located on the outside of the gas-liquid separation membrane 142. The fixing ring 143 can be pressed and fixed by the gas-liquid separation membrane 142, and the gas-liquid separation membrane 142 can be easily disassembled and assembled.

[0023] Among them, the liquid chlorine tail gas recovery equipment includes the following process steps: S1, the condenser is started by the controller 11, and the cooling water is transported to the inside of the serpentine heat exchange tube 6 through the liquid inlet pipe 7, and the serpentine heat exchange tube 6 is cooled by the cooling water and then refluxed to the inside of the condenser through the reflux pipe 8 for recycling; S2, controlling the chlorine compressor 3 to drive, while the chlorine compressor 3 is driven, the liquid chlorine tail gas generated inside the liquid chlorine filling equipment 1 is compressed through the tail gas exhaust pipe 2 and then transported to the inside of the cooling device 5 through the air intake pipe 4; S3, the chlorine in the liquid chlorine tail gas is cooled and gradually liquefied into liquid chlorine after contacting the serpentine heat exchange tube 6, and the formed liquid chlorine drips into the inside of the liquid chlorine storage bin for collection, and the remaining unliquefied gas is transported to the inside of the exhaust bin 10 along the S-shaped channel. With the continuous transportation of the liquid chlorine tail gas inside the cooling device 5, the remaining gas inside the exhaust bin 10 is filtered through the gas-liquid separation membrane 142 to filter the liquid contained in the gas, and the filtered gas is discharged through the exhaust pipe 12 through the adapter 141; S4, when the pressure sensor 21 detects that the pressure generated by the liquid chlorine is greater than the set value, the controller 11 controls the solenoid valve 20 to start, and the channel between the first drain pipe 15, the second drain pipe 16 or the third drain pipe 17 and the manifold 18 is opened by driving the solenoid valve 20. At this time, the liquid chlorine collected in the liquid chlorine storage bin is discharged to the inside of the liquid nitrogen storage tank 19 through the first drain pipe 15, the second drain pipe 16 or the third drain pipe 17 and the manifold 18 for collection and storage. The liquid chlorine in the liquid nitrogen storage tank 19 is recycled after being vaporized. When the pressure sensor 21 detects that the pressure generated by the liquid chlorine is less than the set value, the controller 11 controls the solenoid valve 20 to close, and the channel between the first drain pipe 15, the second drain pipe 16 or the third drain pipe 17 and the manifold 18 is cut off to ensure that each liquid chlorine storage bin reserves enough liquid chlorine to seal the first drain pipe 15, the second drain pipe 16 or the third drain pipe 17; S5. When the gas flow meter 22 detects that the gas flow discharged from the exhaust pipe 12 is less than the set value, the controller 11 controls the vacuum pump 133 to be driven. While the vacuum pump 133 is driven, the remaining unliquefied gas in the cooling device 5 is extracted through the first air pipe 131. After extraction, the gas is blown to the surface of the gas-liquid separation membrane 142 through the exhaust hole inside the nozzle 136 through the second air pipe 132, and the liquid attached to the surface of the gas-liquid separation membrane 142 is cleaned by the generated airflow.

[0024] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0025] The above description is only a preferred embodiment of the present application and an explanation of the technical principles used. Those skilled in the art should understand that the scope of the invention involved in the present application is not limited to the technical solution formed by a specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the inventive concept. For example, the above features are replaced with (but not limited to) technical features with similar functions disclosed in the present application.

Claims

1. A liquid chlorine tail gas recovery device and process, comprising a liquid chlorine filling device (1), a chlorine compressor (3) connected to the liquid chlorine filling device (1) through a tail gas exhaust pipe (2), and a cooling device (5) connected to the chlorine compressor (3) through an air inlet pipe (4), characterized in that: A serpentine heat exchange tube (6) is arranged inside the cooling device (5); the top end of the serpentine heat exchange tube (6) extending outside the cooling device (5) is connected to a liquid inlet tube (7) and a return tube (8); a partition plate (9) located inside the serpentine heat exchange tube (6) is arranged inside the cooling device (5); and an exhaust bin (10) and a controller (11) fixedly installed and electrically connected to the chlorine compressor (3) are respectively arranged on a side of the cooling device (5) away from the air inlet tube (4); an exhaust pipe (12) is connected to the inside of one side of the exhaust bin (10); and a cleaning structure (11) connected to the cooling device (5) is installed on the top of the exhaust bin (10). 13), the exhaust pipe (12) extends to one end of the exhaust chamber (10) and is connected to a gas-liquid separation mechanism (14) on the outside; the interior of the bottom of the cooling device (5) is connected to a first drain pipe (15), a second drain pipe (16) and a third drain pipe (17); the bottom ends of the first drain pipe (15), the second drain pipe (16) and the third drain pipe (17) are connected to a manifold (18); the manifold (18) is connected to a liquid nitrogen storage tank (19); and electromagnetic valves (20) electrically connected to the controller (11) are provided in the middle of the first drain pipe (15), the second drain pipe (16) and the third drain pipe (17).

2. A liquid chlorine tail gas recovery equipment and process according to claim 1, characterized in that: The bottom of the cooling device (5) located on one side of the first liquid discharge pipe (15), the second liquid discharge pipe (16) and the third liquid discharge pipe (17) is provided with a pressure sensor (21) electrically connected to the controller (11).

3. A liquid chlorine tail gas recovery device and process according to claim 1, characterized in that: A gas flow meter (22) electrically connected to the controller (11) is provided on the outer side of one end of the exhaust pipe (12) extending outside the exhaust bin (10).

4. A liquid chlorine tail gas recovery device and process according to claim 1, characterized in that: The cleaning structure (13) comprises a first air pipe (131) connected to one side of the top of the cooling device (5) and a second air pipe (132) connected to one side of the top of the exhaust bin (10); the outer sides of the top ends of the first air pipe (131) and the second air pipe (132) are connected to a vacuum pump (133) fixedly mounted above the exhaust bin (10); the outer sides of the first air pipe (131) and the second air pipe (132) are respectively provided with a first one-way valve (134) and a second one-way valve (135); the outer sides of the bottom end of the second air pipe (132) extending to the inner side of the exhaust bin (10) are connected to a nozzle (136).

5. A liquid chlorine tail gas recovery device and process according to claim 4, characterized in that: The exhaust holes inside the nozzle (136) are arranged in a rectangular shape.

6. A liquid chlorine tail gas recovery equipment and process according to claim 1, characterized in that: The gas-liquid separation mechanism (14) comprises an adapter (141) connected to the outside of the exhaust pipe (12) and having an end face with an inclined design on one side, a fixing ring (143) being sleeved on the inside of the adapter (141), and a fixing ring (143) located on the outside of the gas-liquid separation membrane (142) being sleeved on the inside thread of the adapter (141).

7. The liquid chlorine tail gas recovery equipment and process according to claim 1 are characterized in that: the liquid chlorine tail gas recovery equipment comprises the following process steps: S1, the condenser is started by the controller 11, and the cooling water is transported to the inside of the serpentine heat exchange tube 6 through the liquid inlet pipe 7, and the serpentine heat exchange tube 6 is cooled by the cooling water and then refluxed to the inside of the condenser through the reflux pipe 8 for recycling; S2, controlling the chlorine compressor 3 to drive, while the chlorine compressor 3 is driven, the liquid chlorine tail gas generated inside the liquid chlorine filling equipment 1 is compressed through the tail gas exhaust pipe 2 and then transported to the inside of the cooling device 5 through the air intake pipe 4; S3, the chlorine in the liquid chlorine tail gas is cooled and gradually liquefied into liquid chlorine after contacting the serpentine heat exchange tube 6, and the formed liquid chlorine drips into the inside of the liquid chlorine storage bin for collection, and the remaining unliquefied gas is transported to the inside of the exhaust bin 10 along the S-shaped channel. With the continuous transportation of the liquid chlorine tail gas inside the cooling device 5, the remaining gas inside the exhaust bin 10 passes through the gas-liquid separation membrane 142 and the adapter 141 and is discharged through the exhaust pipe 12; S4, when the pressure sensor 21 detects that the pressure generated by the liquid chlorine is greater than the set value, the controller 11 controls the solenoid valve 20 to start, and the passage between the first drain pipe 15, the second drain pipe 16 or the third drain pipe 17 and the manifold 18 is opened by driving the solenoid valve 20. At this time, the liquid chlorine collected in the liquid chlorine storage bin is discharged to the interior of the liquid nitrogen storage tank 19 through the first drain pipe 15, the second drain pipe 16 or the third drain pipe 17 and the manifold 18 for collection and storage. When the pressure sensor 21 detects that the pressure generated by the liquid chlorine is less than the set value, the controller 11 controls the solenoid valve 20 to close, and the passage between the first drain pipe 15, the second drain pipe 16 or the third drain pipe 17 and the manifold 18 is cut off; S5. When the gas flow meter 22 detects that the gas flow discharged from the exhaust pipe 12 is less than the set value, the controller 11 controls the vacuum pump 133 to be driven. While the vacuum pump 133 is driven, the remaining unliquefied gas in the cooling device 5 is extracted through the first air pipe 131. After extraction, the gas is blown to the surface of the gas-liquid separation membrane 142 through the exhaust hole inside the nozzle 136 through the second air pipe 132, and the liquid attached to the surface of the gas-liquid separation membrane 142 is cleaned by the generated airflow.

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