A C4F7N / CO2 mixed gas liquefaction separation, enrichment, distillation and purification device and method

Abstract

A device and method for liquefying, separating, enriching, rectifying and purifying a C4F7N / CO2 mixed gas belongs to the technical field of insulating gas treatment for electrical equipment, and solves the problem of how to separate and purify C4F7N in a C4F7N / CO2 mixed gas. The technical solution of the present invention first pressurizes and cools the input mixed gas and liquefies it through a first compressor and an air cooling device, and the liquefied C4F7N is transferred to a second temporary storage tank in a distillation unit for storage. The unliquefied mixed gas is input into an organic membrane separation device for enrichment and separation of C4F7N, and then input into a distillation tower for rectification and purification, thereby avoiding the phenomenon that low-temperature distillation is suitable for the separation and purification of high-concentration target objects, but has poor separation effect and high energy consumption for low-concentration mixed gases; the tail gas treatment pipeline neutralizes and absorbs CO2 in the tail gas of the organic membrane separation device and the distillation tower, and the C4F7N in the tail gas is recycled into the pressurization and cooling liquefaction pipeline for re-separation. No tail gas is discharged throughout the process, thereby avoiding air pollution.

Description

Technical Field

[0001] The present invention belongs to the technical field of insulating gas treatment for electrical equipment, and relates to a device and method for liquefying, separating, enriching, rectifying and purifying a C4F7N / CO2 mixed gas. Background Art

[0002] Sulfur hexafluoride (SF6) gas has excellent insulation and arc-extinguishing properties. SF6 electrical equipment has become a core component of urban power supply and ultra-high voltage (UHV) transmission and transformation equipment. However, its strong greenhouse effect has led to its emission ban and use restrictions internationally. Therefore, there is an urgent need to develop new environmentally friendly insulating gases to completely replace SF6, a greenhouse gas used in power grids.

[0003] Perfluoroisobutyronitrile (C4F7N) is the most promising alternative to SF6 gas and has been widely used in power grids. Due to its high liquefaction temperature (at standard atmospheric pressure, C4F7N liquefies at -4.7°C, while CO2 liquefies at -78.5°C, a temperature much lower than that of C4F7N), C4F7N must be mixed with CO2 when used in electrical equipment. The C4F7N / CO2 mixture must be recovered and processed after use. With the large-scale application of C4F7N, its recovery and processing are becoming increasingly important. Summary of the Invention

[0004] The technical problem to be solved by the present invention is how to separate and purify C4F7N in C4F7N / CO2 mixed gas.

[0005] The present invention solves the above technical problems through the following technical solutions:

[0006] A C4F7N / CO2 mixed gas liquefaction, separation, enrichment, rectification and purification device comprises: a pressurizing and cooling liquefaction pipeline (11), an organic membrane enrichment and separation pipeline (12), a transfer pipeline (13), a rectification unit (14), and an exhaust gas treatment pipeline (15); the pressurizing and cooling liquefaction pipeline (11) comprises: a first pressure sensor (P1), a first solenoid valve (V1), a first compressor (K1), a first check valve (111), an air cooling device (112), and a first temporary storage tank (113); the organic membrane enrichment and separation pipeline (12) comprises: a second solenoid valve (V2), a second check valve (121), a gas heater ( 122), an organic membrane separation device (123), and a third solenoid valve (V3); the transfer pipeline (13) includes: a second manual valve (ST2), a third compressor (K3), a third check valve (131), and a third manual valve (ST3); the distillation unit (14) includes: a fourth solenoid valve (V4), a second compressor (K2), a fourth check valve (141), a first manual valve (ST1), a second temporary storage tank (142), a distillation tower (143), and a sixth solenoid valve (V6); the tail gas treatment pipeline (15) includes: an alkali solution neutralization tank (151), a drying tower (152), and a seventh solenoid valve (V7);

[0007] One end of the first solenoid valve (V1) serves as the input end of the device, the other end of the first solenoid valve (V1) is sealedly connected to the input end of the first compressor (K1), the output end of the first compressor (K1) is sealedly connected to the input end of the first one-way valve (111), the output end of the first one-way valve (111) is sealedly connected to the input end of the air cooling device (112), the output end of the air cooling device (112) is sealedly connected to the input end of the first temporary storage tank (113), and the first pressure sensor (P1) is sealedly installed at the input end of the device; one end of the second solenoid valve (V2) is sealedly connected to the top of the first temporary storage tank (113), the other end of the second solenoid valve (V2) is sealedly connected to the input end of the second one-way valve (121), and the second one-way valve (121) is sealedly connected to the input end of the second one-way valve (121). The output end of the second one-way valve (121) is sealed connected to the input end of the gas heater (122), the output end of the gas heater (122) is sealed connected to the input end of the organic membrane separation device (123), the finished gas output end of the organic membrane separation device (123) is sealed connected to the distillation unit (14), and the exhaust gas output end of the organic membrane separation device (123) is sealed connected to the tail gas treatment pipeline (15); one end of the second manual valve (ST2) is sealed connected to the bottom of the first temporary storage tank (113), the other end of the second manual valve (ST2) is sealed connected to the input end of the third compressor (K3), and the output end of the third compressor (K3) is sealed connected to the input end of the third one-way valve (131). The output end of the third one-way valve (131) is sealedly connected to one end of the third manual valve (ST3), and the other end of the third manual valve (ST3) is sealedly connected to the distillation unit (14); one end of the fourth solenoid valve (V4) is sealedly connected to the finished gas output end of the organic membrane separation device (123), the other end of the fourth solenoid valve (V4) is sealedly connected to the input end of the second compressor (K2), the output end of the second compressor (K2) is sealedly connected to the input end of the fourth one-way valve (141), the output end of the fourth one-way valve (141) is sealedly connected to one end of the first manual valve (ST1), the other end of the first manual valve (ST1) is sealedly connected to the bottom of the distillation tower (143), and the top of the distillation tower (143) is sealed to the third one-way valve (131). One end of the sixth solenoid valve (V6) is sealed and connected, the other end of the sixth solenoid valve (V6) is sealed and connected to the tail gas treatment pipeline (15), and the top of the second temporary storage tank (142) is sealed and connected to the bottom of the distillation tower (143); the input end of the alkali solution neutralization tank (151) is sealed and connected to the first output end of the distillation unit (14) and the second output end of the organic membrane enrichment and separation pipeline (12), respectively, the output end of the alkali solution neutralization tank (151) is sealed and connected to the bottom input end of the drying tower (152), the top output end of the drying tower (152) is sealed and connected to one end of the seventh solenoid valve (V7), and the other end of the seventh solenoid valve (V7) is sealed and connected between the first solenoid valve (V1) and the first compressor (K1).

[0008] The device of the present invention first pressurizes and cools down the input C4F7N / CO2 mixed gas and liquefies it through the first compressor (K1) and the air cooling device (112) in the pressurization and cooling liquefaction pipeline (11). The liquefied C4F7N is transferred to the second temporary storage tank (142) in the distillation unit (14) for storage. The unliquefied C4F7N and CO2 mixed gas is input to the organic membrane separation device (123) in the organic membrane enrichment and separation pipeline (12) for enrichment and separation of C4F7N. The enriched and separated C4F7N is then input to the The product is distilled and purified in the distillation tower (143) in the distillation unit (14), which effectively solves the problem that low-temperature distillation is suitable for separation and purification of high-concentration target substances, but has poor separation effect and high energy consumption for low-concentration mixed gases; the device is provided with an exhaust gas treatment pipeline (15) to neutralize and absorb CO2 in the exhaust gas of the organic membrane separation device (123) and the distillation tower (143), and the C4F7N in the exhaust gas is recycled and returned to the pressurization and cooling liquefaction pipeline (11) for further separation, without exhaust gas exhaust in the whole process, thus avoiding air pollution.

[0009] Furthermore, the pressurizing and cooling liquefaction pipeline (11) further comprises a pressure reducing valve (JY), wherein the pressure reducing valve (JY) is sealed and installed between the air cooling device (112) and the first temporary storage tank (113).

[0010] Furthermore, a liquid level observation window is provided on the first temporary storage tank (113) for observing the liquid level inside the first temporary storage tank (113).

[0011] Furthermore, the distillation unit (14) further comprises: a fifth solenoid valve (V5), a refrigerator (144), a fourth manual valve (ST4), and a steel cylinder; one end of the fifth solenoid valve (V5) is sealedly connected to the distillation tower (143), the other end of the fifth solenoid valve (V5) is sealedly connected to a port of the refrigerator (144), and the other port of the refrigerator (144) is sealedly connected to the distillation tower (143).

[0012] Furthermore, the distillation unit (14) further comprises: one end of the fourth manual valve (ST4) is sealedly connected to the bottom of the second temporary storage tank (142), and the other end of the fourth manual valve (ST4) is sealedly connected to the cylinder.

[0013] A method based on the C4F7N / CO2 mixed gas liquefaction separation, enrichment, distillation and purification device comprises the following steps: S1, pressurizing and cooling the C4F7N / CO2 mixed gas to liquefy it, and transferring the liquefied C4F7N; S2, enriching and separating the unliquefied C4F7N and CO2 mixed gas through an organic membrane; S3, distilling and purifying the C4F7N; and S4, treating the tail gas.

[0014] Furthermore, the method for pressurizing, cooling and liquefying the C4F7N / CO2 mixed gas in step S1 is specifically as follows: after the C4F7N / CO2 mixed gas passes through the first solenoid valve (V1), the first compressor (K1), the first one-way valve (111), and the air cooling device (112), the air cooling device (112) cools the C4F7N / CO2 mixed gas, and the first compressor (K1) compresses the C4F7N / CO2 mixed gas into the first temporary storage tank (113), and the C4F7N / CO2 mixed gas is cooled by the air cooling device (112). Due to the increase in pressure, C4F7N in the mixed gas is liquefied and stored at the bottom of the first temporary storage tank (113), and part of the C4F7N and CO2 mixed gas that has not been liquefied is at the top of the first temporary storage tank (113); the method for transferring the liquefied C4F7N is specifically as follows: opening the second manual valve (ST2) and the third manual valve (ST3), starting the third compressor (K3), and transferring the liquid C4F7N at the bottom of the first temporary storage tank (113) to the second temporary storage tank (142).

[0015] Furthermore, the method for organic membrane enrichment and separation of the unliquefied C4F7N and CO2 mixed gas described in step S2 is specifically as follows: the second solenoid valve (V2) is opened, and the unliquefied C4F7N and CO2 mixed gas at the top of the first temporary storage tank (113) passes through the second one-way valve (121) and the gas heater (122) in sequence and then enters the organic membrane separation device (123) for separation, and the gas heater (122) heats the unliquefied C4F7N and CO2 mixed gas.

[0016] Furthermore, the method for rectifying and purifying C4F7N in step S3 is specifically as follows: opening the fourth solenoid valve (V4) and the first manual valve (ST1), starting the second compressor (K2), and inputting the C4F7N separated from the finished gas output end of the organic membrane separation device (123) into the rectifying tower (143) for rectification and purification; the C4F7N gas continuously undergoes a gas-liquid two-phase transition in the rectifying tower (143), gaseous CO2 accumulates at the top of the rectifying tower (143), and liquid C4F7N accumulates at the bottom of the second temporary storage tank (142).

[0017] Furthermore, the tail gas treatment method described in step S4 is specifically as follows:

[0018] S41, opening the third solenoid valve (V3) to input the gas output from the exhaust gas output end of the organic membrane separation device (123) into the alkali solution neutralization tank (151) to neutralize and absorb CO2, and the absorbed gas is dried by the drying tower (152), and then recycled through the seventh solenoid valve (V7) to the pressurization and cooling liquefaction pipeline (11) for further separation;

[0019] S42, open the sixth solenoid valve (V6) to input the gas gathered at the top of the distillation tower (143) into the alkaline solution neutralization tank (151) to neutralize and absorb CO2. The absorbed gas is dried by the drying tower (152) and then recycled by the seventh solenoid valve (V7) to the pressurization and cooling liquefaction pipeline (11) for further separation.

[0020] The advantages of the present invention are:

[0021] The device of the present invention first pressurizes and cools down the input C4F7N / CO2 mixed gas and liquefies it through the first compressor (K1) and the air cooling device (112) in the pressurization and cooling liquefaction pipeline (11). The liquefied C4F7N is transferred to the second temporary storage tank (142) in the distillation unit (14) for storage. The unliquefied C4F7N and CO2 mixed gas is input to the organic membrane separation device (123) in the organic membrane enrichment and separation pipeline (12) for enrichment and separation of C4F7N. The enriched and separated C4F7N is then input to the The product is distilled and purified in the distillation tower (143) in the distillation unit (14), which effectively solves the problem that low-temperature distillation is suitable for separation and purification of high-concentration target substances, but has poor separation effect and high energy consumption for low-concentration mixed gases; the device is provided with an exhaust gas treatment pipeline (15) to neutralize and absorb CO2 in the exhaust gas of the organic membrane separation device (123) and the distillation tower (143), and the C4F7N in the exhaust gas is recycled and returned to the pressurization and cooling liquefaction pipeline (11) for further separation, without exhaust gas exhaust in the whole process, thus avoiding air pollution. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a structural block diagram of the C4F7N / CO2 mixed gas liquefaction separation, enrichment, rectification and purification device of the present invention;

[0023] Figure 2 This is a detailed structural diagram of a C4F7N / CO2 mixed gas liquefaction separation, enrichment, rectification and purification device of the present invention;

[0024] Figure 3 It is a flow chart of the C4F7N / CO2 mixed gas liquefaction separation, enrichment, distillation and purification method of the present invention. DETAILED DESCRIPTION

[0025] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0026] The technical solution of the present invention is further described below with reference to the accompanying drawings and specific embodiments:

[0027] Example 1

[0028] like Figure 1 As shown, a C4F7N / CO2 mixed gas liquefaction separation, enrichment, distillation and purification device includes: a pressurization and cooling liquefaction pipeline 11, an organic membrane enrichment and separation pipeline 12, a transfer pipeline 13, a distillation unit 14, and an exhaust gas treatment pipeline 15.

[0029] like Figure 2 As shown, the pressurization and cooling liquefaction pipeline 11 includes: a first pressure sensor P1, a first solenoid valve V1, a first compressor K1, a first check valve 111, an air cooling device 112, a pressure reducing valve JY, and a first temporary storage tank 113; the organic membrane enrichment and separation pipeline 12 includes: a second solenoid valve V2, a second check valve 121, a gas heater 122, an organic membrane separation device 123, and a third solenoid valve V3; the transfer pipeline 13 includes: a second manual valve ST2, a third compressor K3, a third check valve 131, and a third manual valve ST3; the distillation unit 14 includes: a fourth solenoid valve V4, a second compressor K2, a fourth check valve 141, a first manual valve ST1, a second temporary storage tank 142, a fourth manual valve ST4, a distillation tower 143, a fifth solenoid valve V5, a refrigerator 144, and a sixth solenoid valve V6; the tail gas treatment pipeline 15 includes: an alkali solution neutralization tank 151, a drying tower 152, and a seventh solenoid valve V7.

[0030] One end of the first solenoid valve V1 serves as the input end of the device, and the other end of the first solenoid valve V1 is sealedly connected to the input end of the first compressor K1. The output end of the first compressor K1 is sealedly connected to the input end of the first one-way valve 111, and the output end of the first one-way valve 111 is sealedly connected to the input end of the air cooling device 112. The output end of the air cooling device 112 is sealedly connected to the input end of the first temporary storage tank 113. The first pressure sensor P1 is sealedly installed at the input end of the device, and the pressure reducing valve JY is sealedly installed between the air cooling device 112 and the first temporary storage tank 113. A liquid level observation window is provided on the first temporary storage tank 113 for observing the liquid level inside the first temporary storage tank 113.

[0031] One end of the second solenoid valve V2 is sealedly connected to the top of the first temporary storage tank 113, the other end of the second solenoid valve V2 is sealedly connected to the input end of the second one-way valve 121, the output end of the second one-way valve 121 is sealedly connected to the input end of the gas heater 122, the output end of the gas heater 122 is sealedly connected to the input end of the organic membrane separation device 123, the exhaust gas output end of the organic membrane separation device 123 is sealedly connected to one end of the third solenoid valve V3, the other end of the third solenoid valve V3 is sealedly connected to the input end of the alkali solution neutralization tank 151, and the finished gas output end of the organic membrane separation device 123 is sealedly connected to one end of the fourth solenoid valve V4.

[0032] One end of the second manual valve ST2 is sealed to the bottom of the first temporary storage tank 113, the other end of the second manual valve ST2 is sealed to the input end of the third compressor K3, the output end of the third compressor K3 is sealed to the input end of the third one-way valve 131, the output end of the third one-way valve 131 is sealed to one end of the third manual valve ST3, and the other end of the third manual valve ST3 is sealed to the bottom of the distillation tower 143.

[0033] One end of the fourth solenoid valve V4 is sealedly connected to the finished gas output end of the organic membrane separation device 123, the other end of the fourth solenoid valve V4 is sealedly connected to the input end of the second compressor K2, the output end of the second compressor K2 is sealedly connected to the input end of the fourth one-way valve 141, the output end of the fourth one-way valve 141 is sealedly connected to one end of the first manual valve ST1, the other end of the first manual valve ST1 is sealedly connected to the bottom of the distillation tower 143, the top of the distillation tower 143 is sealed to one end of the sixth solenoid valve V6, and the sixth solenoid valve V 6 is sealedly connected to the input end of the alkali solution neutralization tank 151, the top of the second temporary storage tank 142 is sealedly connected to the bottom of the distillation tower 143, one end of the fourth manual valve ST4 is sealedly connected to the bottom of the second temporary storage tank 142, and the other end of the fourth manual valve ST4 is sealedly connected to the cylinder; one end of the fifth solenoid valve V5 is sealedly connected to the distillation tower 143, the other end of the fifth solenoid valve V5 is sealedly connected to one port of the refrigerator 144, and the other port of the refrigerator 144 is sealedly connected to the distillation tower 143.

[0034] The exhaust gas treatment pipeline 15 includes: an alkali liquid neutralization tank 151, a drying tower 152, and a seventh solenoid valve V7; the input end of the alkali liquid neutralization tank 151 is sealedly connected to the third solenoid valve V3 and the sixth solenoid valve V6, respectively, the output end of the alkali liquid neutralization tank 151 is sealedly connected to the bottom input end of the drying tower 152, the top output end of the drying tower 152 is sealedly connected to one end of the seventh solenoid valve V7, and the other end of the seventh solenoid valve V7 is sealedly connected between the first solenoid valve V1 and the first compressor K1.

[0035] The pressurizing and cooling liquefaction pipeline 11 includes: a first pressure sensor P1, a first solenoid valve V1, a first compressor K1, a first check valve 111, an air cooling device 112, a pressure reducing valve JY, and a first temporary storage tank 113; the organic membrane enrichment and separation pipeline 12 includes: a second solenoid valve V2, a second check valve 121, a gas heater 122, an organic membrane separation device 123, and a third solenoid valve V3; the transfer pipeline 13 includes: a second manual valve ST2, a third compressor K3, a third check valve 131, and a third manual valve ST3; the distillation unit 14 includes: a fourth solenoid valve V4, a second compressor K2, a fourth check valve 141, a first manual valve ST1, a second temporary storage tank 142, a fourth manual valve ST4, a distillation tower 143, a fifth solenoid valve V5, a refrigerator 144, and a sixth solenoid valve V6; the tail gas treatment pipeline 15 includes: an alkali neutralization tank 151, a drying tower 152, and a seventh solenoid valve V7.

[0036] like Figure 3 As shown, the working process of the device is as follows:

[0037] 1. Pressurization and cooling liquefaction of C4F7N / CO2 mixed gas

[0038] After the C4F7N / CO2 mixed gas passes through the first solenoid valve V1, the first compressor K1, the first one-way valve 111, and the air cooling device 112, the air cooling device 112 cools the C4F7N / CO2 mixed gas. The first compressor K1 compresses the C4F7N / CO2 mixed gas into the first temporary storage tank 113. Due to the increase in pressure, the C4F7N in the mixed gas is liquefied and stored at the bottom of the first temporary storage tank 113. Some of the C4F7N and CO2 mixed gas that has not been liquefied is at the top of the first temporary storage tank 113. At this time, the C4F7N content in the C4F7N and CO2 mixed gas that has not been liquefied at the top of the first temporary storage tank 113 is low and needs to be enriched and separated.

[0039] 2. Organic membrane enrichment and separation of unliquefied C4F7N and CO2 mixed gas

[0040] The second solenoid valve V2 is opened, and the unliquefied C4F7N and CO2 mixed gas at the top of the first temporary storage tank 113 passes through the second one-way valve 121 and the gas heater 122 in sequence before entering the organic membrane separation device 123 for separation. The gas heater 122 heats the unliquefied C4F7N and CO2 mixed gas, maintaining the temperature of the mixed gas at 40°C to 55°C. At this temperature, the organic membrane separation efficiency of the mixed gas is the highest. After separation by the organic membrane separation device 123, the purity of the C4F7N separated from the finished gas output end of the organic membrane separation device 123 reaches over 90%. The gas output from the exhaust gas output end of the organic membrane separation device 123 is mainly CO2, with a small amount of C4F7N also present.

[0041] 3. Transfer of liquefied C4F7N

[0042] The second manual valve ST2 and the third manual valve ST3 are opened, and the third compressor K3 is turned on to transfer the liquid C4F7N at the bottom of the first temporary storage tank 113 to the second temporary storage tank 142.

[0043] 4. Distillation and purification of C4F7N

[0044] Open the fourth solenoid valve V4 and the first manual valve ST1, start the second compressor K2, and input the C4F7N separated from the finished gas output end of the organic membrane separation device 123 into the distillation tower 143 for distillation and purification.

[0045] The C4F7N gas continuously undergoes a gas-liquid phase transition in the distillation tower 143, and the gaseous CO2 gathers at the top of the distillation tower 143. In addition to a large amount of CO2, the gas gathered at the top of the distillation tower 143 also contains a small amount of C4F7N. The liquid C4F7N gathers at the bottom of the second temporary storage tank 142.

[0046] 5. Exhaust gas treatment

[0047] Open the third solenoid valve V3 to input the gas output from the exhaust gas output end of the organic membrane separation device 123 into the alkaline solution neutralization tank 151 to neutralize and absorb CO2. The absorbed gas is dried in the drying tower 152 and then recycled through the seventh solenoid valve V7 to the pressurization and cooling liquefaction pipeline 11 for further separation.

[0048] Open the sixth solenoid valve V6 and input the gas gathered at the top of the distillation tower 143 into the alkaline solution neutralization tank 151 to neutralize and absorb CO2. The absorbed gas is dried by the drying tower 152 and then recycled through the seventh solenoid valve V7 to the pressurization and cooling liquefaction pipeline 11 for further separation.

[0049] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A method for liquefying, separating, enriching, and distilling a C4F7N / CO2 mixed gas, characterized in that: include: A pressurizing and cooling liquefaction pipeline (11), an organic membrane enrichment and separation pipeline (12), a transfer pipeline (13), a distillation unit (14) and an exhaust gas treatment pipeline (15); the pressurizing and cooling liquefaction pipeline (11) includes: a first pressure sensor (P1), a first solenoid valve (V1), a first compressor (K1), a first check valve (111), an air cooling device (112) and a first temporary storage tank (113); the organic membrane enrichment and separation pipeline (12) includes: a second solenoid valve (V2), a second check valve (121), a gas heater (122), an organic membrane separation device (123 ) and a third solenoid valve (V3); the transfer pipeline (13) includes: a second manual valve (ST2), a third compressor (K3), a third one-way valve (131) and a third manual valve (ST3); the distillation unit (14) includes: a fourth solenoid valve (V4), a second compressor (K2), a fourth one-way valve (141), a first manual valve (ST1), a second temporary storage tank (142), a distillation tower (143) and a sixth solenoid valve (V6); the tail gas treatment pipeline (15) includes: an alkali solution neutralization tank (151), a drying tower (152) and a seventh solenoid valve (V7); One end of the first solenoid valve (V1) serves as the input end of the device, the other end of the first solenoid valve (V1) is sealedly connected to the input end of the first compressor (K1), the output end of the first compressor (K1) is sealedly connected to the input end of the first one-way valve (111), the output end of the first one-way valve (111) is sealedly connected to the input end of the air cooling device (112), the output end of the air cooling device (112) is sealedly connected to the input end of the first temporary storage tank (113), and the first pressure sensor (P1) is sealedly installed at the input end of the device; one end of the second solenoid valve (V2) is sealedly connected to the top of the first temporary storage tank (113), and the other end of the second solenoid valve (V2) is sealed to the second one-way valve (121 ), the output end of the second one-way valve (121) is sealed connected to the input end of the gas heater (122), the output end of the gas heater (122) is sealed connected to the input end of the organic membrane separation device (123), the finished gas output end of the organic membrane separation device (123) is sealed connected to the distillation unit (14), the exhaust gas output end of the organic membrane separation device (123) is sealed connected to one end of the third solenoid valve (V3), and the other end of the third solenoid valve (V3) is sealed connected to the input end of the alkali solution neutralization tank (151); one end of the second manual valve (ST2) is sealed connected to the bottom of the first temporary storage tank (113), and the other end of the second manual valve (ST2) is sealed connected to the third compressor (151). The input end of the third compressor (K3) is sealed and connected, the output end of the third one-way valve (131) is sealed and connected, the output end of the third one-way valve (131) is sealed and connected to one end of the third manual valve (ST3), and the other end of the third manual valve (ST3) is sealed and connected to the distillation unit (14); one end of the fourth solenoid valve (V4) is sealed and connected to the finished gas output end of the organic membrane separation device (123), the other end of the fourth solenoid valve (V4) is sealed and connected to the input end of the second compressor (K2), the output end of the second compressor (K2) is sealed and connected to the input end of the fourth one-way valve (141), the output end of the fourth one-way valve (141) is sealed and connected to the output end of the first manual valve (ST1). One end is sealed and connected, the other end of the first manual valve (ST1) is sealed and connected to the bottom of the distillation tower (143), the top of the distillation tower (143) is sealed and connected to one end of the sixth solenoid valve (V6), the other end of the sixth solenoid valve (V6) is sealed and connected to the input end of the alkali solution neutralization tank (151), the top of the second temporary storage tank (142) is sealed and connected to the bottom of the distillation tower (143); the output end of the alkali solution neutralization tank (151) is sealed and connected to the bottom input end of the drying tower (152), the top output end of the drying tower (152) is sealed and connected to one end of the seventh solenoid valve (V7), and the other end of the seventh solenoid valve (V7) is sealed and connected between the first solenoid valve (V1) and the first compressor (K1); The method comprises the following steps: S1, pressurizing and cooling the C4F7N / CO2 mixed gas to liquefy it, and transferring the liquefied C4F7N; the method for pressurizing and cooling the C4F7N / CO2 mixed gas is specifically as follows: after the C4F7N / CO2 mixed gas passes through a first solenoid valve (V1), a first compressor (K1), a first one-way valve (111), and an air cooling device (112), the air cooling device (112) cools the C4F7N / CO2 mixed gas, and the first compressor (K1) compresses the C4F7N / CO2 mixed gas. In the first temporary storage tank (113), due to the increase in pressure, the C4F7N in the mixed gas is liquefied and stored at the bottom of the first temporary storage tank (113), and part of the C4F7N and CO2 mixed gas that has not been liquefied is at the top of the first temporary storage tank (113); the method for transferring the liquefied C4F7N is specifically as follows: opening the second manual valve (ST2) and the third manual valve (ST3), starting the third compressor (K3), and transferring the liquid C4F7N at the bottom of the first temporary storage tank (113) to the second temporary storage tank (142); S2, organic membrane enrichment and separation of the unliquefied C4F7N and CO2 mixed gas, wherein the organic membrane enrichment and separation method of the unliquefied C4F7N and CO2 mixed gas is specifically as follows: opening the second solenoid valve (V2), and the unliquefied C4F7N and CO2 mixed gas at the top of the first temporary storage tank (113) sequentially passes through the second one-way valve (121) and the gas heater (122) and then enters the organic membrane separation device (123) for separation, and the gas heater (122) heats the unliquefied C4F7N and CO2 mixed gas; S3, distillation and purification of C4F7N, the distillation and purification method of C4F7N specifically comprises: opening the fourth solenoid valve (V4) and the first manual valve (ST1), starting the second compressor (K2), and inputting the C4F7N separated from the finished gas output end of the organic membrane separation device (123) into the distillation tower (143) for distillation and purification; the C4F7N gas continuously undergoes a gas-liquid two-phase phase transition in the distillation tower (143), gaseous CO2 accumulates at the top of the distillation tower (143), and liquid C4F7N accumulates at the bottom of the second temporary storage tank (142); S4. Exhaust gas treatment.

2. The method according to claim 1 for the liquefaction, separation, enrichment, and distillation purification of a C4F7N / CO2 mixed gas, characterized in that: The pressurizing and cooling liquefaction pipeline (11) further comprises a pressure reducing valve (JY), wherein the pressure reducing valve (JY) is sealed and installed between the air cooling device (112) and the first temporary storage tank (113).

3. The method for liquefying, separating, enriching, and distilling and purifying a C4F7N / CO2 mixed gas according to claim 1, characterized in that: The first temporary storage tank (113) is provided with a liquid level observation window for observing the liquid level inside the first temporary storage tank (113).

4. The method for liquefying, separating, enriching, and distilling and purifying a C4F7N / CO2 mixed gas according to claim 1, characterized in that: The distillation unit (14) further includes: a fifth solenoid valve (V5) and a refrigerator (144); one end of the fifth solenoid valve (V5) is sealedly connected to the distillation tower (143), the other end of the fifth solenoid valve (V5) is sealedly connected to a port of the refrigerator (144), and the other port of the refrigerator (144) is sealedly connected to the distillation tower (143).

5. The method for liquefying, separating, enriching, and distilling and purifying a C4F7N / CO2 mixed gas according to claim 4, characterized in that: The distillation unit (14) further comprises: a fourth manual valve (ST4) and a steel cylinder, one end of the fourth manual valve (ST4) being sealedly connected to the bottom of the second temporary storage tank (142), and the other end of the fourth manual valve (ST4) being sealedly connected to the steel cylinder.

6. The method for liquefying, separating, enriching, and distilling and purifying a C4F7N / CO2 mixed gas according to claim 1, characterized in that: The tail gas treatment method is specifically as follows: S41, opening the third solenoid valve (V3) to input the gas output from the exhaust gas output end of the organic membrane separation device (123) into the alkaline solution neutralization tank (151) to neutralize and absorb CO2. The absorbed gas is dried by the drying tower (152) and then recycled by the seventh solenoid valve (V7) to the pressurization and cooling liquefaction pipeline (11) for further separation; S42, open the sixth solenoid valve (V6) to input the gas gathered at the top of the distillation tower (143) into the alkaline solution neutralization tank (151) to neutralize and absorb CO2. The absorbed gas is dried by the drying tower (152) and then recycled by the seventh solenoid valve (V7) to the pressurization and cooling liquefaction pipeline (11) for further separation.

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