CN216204682U

CN216204682U - Structure for low-temperature condensation and recovery of volatile gas

Info

Publication number: CN216204682U
Application number: CN202122388336.8U
Authority: CN
Inventors: 谭宏博; 邵博识; 寇西平; 余立; 查俊
Original assignee: Xian Jiaotong University; High Speed Aerodynamics Research Institute of China Aerodynamics Research and Development Center
Current assignee: Xian Jiaotong University; High Speed Aerodynamics Research Institute of China Aerodynamics Research and Development Center
Priority date: 2021-09-30
Filing date: 2021-09-30
Publication date: 2022-04-05
Anticipated expiration: 2031-09-30

Abstract

A structure for recovering volatile gas by low-temperature condensation is formed by connecting a vacuum pump system, a three-stage compressor system and a low-temperature nitrogen condensation heat exchange system; the mixed waste gas is connected with an evacuation inlet of a vacuum pump system and is pumped into a vacuum pump; the gas exhausted from the vacuum pump is cooled by a cooling fan of the air-cooled cooler and then enters a buffer tank before compression; the inlet of the three-stage compressor system is connected with the outlet of the buffer tank before compression, and the gas cooled in the middle of the three-stage compression enters the cold nitrogen-cooled double-pipe heat exchanger and then is introduced into the high-pressure buffer tank before the cold box; the gas in the high-pressure buffer tank in front of the cold box is sent to a low-temperature nitrogen condensation heat exchange system and passes through heat exchanger groups in two paths, wherein one heat exchanger group is cooled by cold nitrogen; the cold source of the other heat exchanger group is two paths of reflux gas for completing cooling; all the condensed liquid is collected in a liquid storage tank and is gasified by an electric heating gasifier for reuse; the utility model can be used in industrial large-scale waste gas treatment occasions, and has obvious treatment effect.

Description

Structure for low-temperature condensation and recovery of volatile gas

Technical Field

The utility model belongs to the technical field of volatile gas recovery, and particularly relates to a structure for recovering volatile gas through low-temperature condensation.

Background

Air pollution is one of the major environmental problems facing human beings at present, and with the increasing requirements for environmental protection, the treatment of volatile gases in the air, especially Volatile Organic Compounds (VOCs) will be continuously paid attention by various industrial departments. In general, there are two concepts for treating volatile gases: one is to control the generation of volatile gas from a source; and the second step is to recover or destroy the volatile gas discharged in the production process. The first method adopts an environment-friendly production method from the source, has the effect of optimally controlling the discharge of VOCs, but does not have the condition of large-scale environment-friendly modification in the industrial field at the present industrial situation. In recent years, effective technologies for recovering VOCs are adopted in different fields, and considerable economic and social benefits are generated, so that the technology is paid attention.

Among the methods for recovering or destroying volatile gases, the condensation method is more classical, and includes cooling condensation and pressurizing condensation, both of which utilize different components in the exhaust gas to separate by different boiling points under the same pressure. Because the VOCs waste gas is usually composed of organic matters and air, and the atmospheric boiling point of most of the organic matters and inorganic matters such as sulfur dioxide, nitrogen oxides and the like is higher than the air liquefaction temperature (90.3K), the organic matters, the sulfur dioxide, the nitrogen oxides and the like can be separated by adopting a condensation method; the low-temperature liquid nitrogen has the storage temperature of 77.3K under normal pressure, is low in price, wide in source, non-toxic, harmless and pollution-free, can be used on a large scale in the industrial field, and is commonly used as a low-temperature condensation coolant.

Chinese patent (publication No. 104501485B) discloses a method for recovering freon by condensing liquid nitrogen, which blows trapped freon into a cold box pipe by means of nitrogen pressure after gasifying liquid nitrogen, liquefies and collects freon by using cold energy of liquid nitrogen, and discharges the heated and gasified nitrogen to the atmosphere after adsorbing by activated carbon. Although the condensation recovery equipment in the form can well recover Freon, power equipment is not needed, and the investment is small; however, in small equipment, the liquid nitrogen gasification can only meet the requirement of recovering low-content Freon in a small space, and the effective purging of a large amount of Freon in a large space is difficult to complete, for example, the gaseous Freon in equipment such as a large Freon refrigerating system, a large storage tank and the like is recycled; the effects of large-scale factory buildings, paint spray rooms, oil and gas storage, laboratories in which dispersed volatile gas is purified and the like cannot be exerted; furthermore, the simple use of vaporized nitrogen to blow off the exhaust gas requires the target equipment to have at least one pair of inlet and outlet, and the single port equipment commonly used in the industry cannot use this purging method.

Disclosure of Invention

In order to overcome the defects of the prior art, the utility model aims to provide a structure for recovering volatile gas by low-temperature condensation, which is suitable for VOCs and various volatile gases with high boiling points and has high universality; the device can be used for large-scale waste gas treatment in the industrial field, has large waste gas treatment capacity and good waste gas treatment effect, and the recovered liquefied gas can be recycled after being gasified, so that the device has outstanding environmental protection performance.

In order to achieve the purpose, the utility model adopts the technical scheme that:

a structure for recovering volatile gas by low-temperature condensation is formed by connecting a vacuum pump system, a three-stage compressor system and a low-temperature nitrogen condensation heat exchange system; the mixed waste gas is connected with a pumping inlet of a vacuum pump system, passes through a first ball valve 1 and is pumped into a vacuum pump 2; gas exhausted from the vacuum pump 2 enters an air-cooled cooler 7 provided with fins, is cooled in the air-cooled cooler 7 and then enters a buffer tank 8 before compression; the inlet of the three-stage compressor system is connected with the outlet of the buffer tank before compression 8, and the gas cooled in the middle of the three-stage compression enters the first sleeve type heat exchanger cooled by cold nitrogen and then is introduced into the high-pressure buffer tank before the cold box 22; the gas in the high-pressure buffer tank 22 in front of the cold box is sent to a low-temperature nitrogen condensation heat exchange system and passes through a heat exchanger group consisting of two sleeve type heat exchangers in two ways, wherein the second sleeve type heat exchanger 26-A and the third sleeve type heat exchanger 26-B of one heat exchanger group are cooled by cold nitrogen; cold sources of a fourth sleeve type heat exchanger 30-A and a fifth sleeve type heat exchanger 30-B of the other heat exchanger group are backflow gas for completing cooling; all the condensed liquid is collected in the liquid storage tank 36 through the gas-liquid separator and gasified by the electric heating gasifier 38 connected with the liquid outlet of the liquid storage tank 36 for reuse.

The vacuum pump system comprises a vacuum pump 2, wherein the vacuum pump 2 is connected with two automatic adjusting and compressing front buffer tanks 8 in front and back, and a first proportional valve 3 and a second proportional valve 4 of an electric bypass for maintaining micro-positive pressure are arranged.

And a second ball valve 5 and a third ball valve 6 which are manually opened and used for exhausting are arranged at the front and the back of the vacuum pump 2, and are used for directly discharging gas to a buffer tank 8 before compression to normal pressure when the gauge pressure of the evacuated vacuum pump system is positive.

The three-stage compressor system comprises a first-stage compressor 9, a second-stage compressor 11 and a third-stage compressor 14, wherein the inlet of the first-stage compressor 9 is connected with the outlet of a buffer tank 8 before compression, and a first compressor after-cooling device 10, a second compressor after-cooling device 12 and a third compressor after-cooling device 15 are arranged behind the first-stage compressor 9, the second-stage compressor 11 and the third-stage compressor 14; a first gas-liquid separator 13 and a second gas-liquid separator 16 are arranged behind the second-stage compressor 11 and the third-stage compressor 14; the liquid outlets of the first gas-liquid separator 13 and the second gas-liquid separator 16 are provided with a first one-way check valve 17 and a second one-way check valve 18, and the outlets of the first one-way check valve 17 and the second one-way check valve 18 are connected with a liquid storage tank 36.

And a gas outlet of the second gas-liquid separator 16 is connected with a tube side inlet of the first sleeve type heat exchanger 19, the compressed gas and cold nitrogen entering from the cold nitrogen inlet A are subjected to countercurrent heat exchange and are condensed and then are introduced into a third gas-liquid separator 20, and gas led out from a gas outlet of the third gas-liquid separator 20 is injected into a front high-pressure buffer tank 22 of the cold box through a fifth ball valve 21.

The working medium gas to be treated in the low-temperature nitrogen condensation heat exchange system passes through a shell pass, the gas for cooling passes through a tube pass, and both paths are countercurrent heat exchange; a cold nitrogen source is connected with the tube side of the third sleeve type heat exchanger 26-B, and nitrogen and treated waste gas which sequentially pass through the third sleeve type heat exchanger 26-B and the second sleeve type heat exchanger 26-A are discharged to the atmosphere; the treated working medium gas is led out from the lower part of a front high-pressure buffer tank 22 of the cold box, passes through a sixth ball valve 23, is divided into two paths, passes through a second needle valve 25 and a first needle valve 24 respectively, and enters a heat exchanger group consisting of a second sleeve type heat exchanger 26-A and a third sleeve type heat exchanger 26-B and a shell side inlet of a heat exchanger group consisting of a fourth sleeve type heat exchanger 30-A and a fifth sleeve type heat exchanger 30-B respectively; the shell-side outlets of the second sleeve-type heat exchanger 26-A and the fourth sleeve-type heat exchanger 30-A are simultaneously connected with a fourth gas-liquid separator 27, the gas outlet of the fourth gas-liquid separator 27 is divided into two paths to be connected with the shell-side inlets of the third sleeve-type heat exchanger 26-B and the fifth sleeve-type heat exchanger 30-B, and a low-temperature valve 31 is arranged on the shell-side inlet pipeline of the fifth sleeve-type heat exchanger 30-B; the shell side outlets of the third sleeve type heat exchanger 26-B and the fifth sleeve type heat exchanger 30-B are simultaneously connected with a fifth gas-liquid separator 28, the gas outlet of the fifth gas-liquid separator 28 passes through a first reducing valve 29 and then is connected with the lower side inlet of the tube side of the fifth sleeve type heat exchanger 30-B, and the low-temperature backflow gas separated by the fifth gas-liquid separator 28 serves as refrigerant gas and sequentially passes through the fifth sleeve type heat exchanger 30-B and the fourth sleeve type heat exchanger 30-A.

The liquid outlets of the third gas-liquid separator 20, the fourth gas-liquid separator 27 and the fifth gas-liquid separator 28 respectively pass through a fourth reducing valve 34, a third reducing valve 33 and a second reducing valve 32 and then enter a liquid storage tank 36.

The exhaust port of the liquid storage tank 36 is connected with the inlet of the buffer tank 8 before compression of the vacuum pump system through a fifth reducing valve 35; the liquid outlet of the liquid storage tank 36 is connected to an electric heating vaporizer 38 via a sixth pressure reducing valve 37.

Compared with the prior art, the utility model has the following advantages:

the whole process of the utility model is a physical process, does not relate to adsorption, absorption and various chemical treatment processes, is suitable for VOCs including Freon and various volatile gases with high boiling points, and has high universality; the device is provided with fluid machines such as a vacuum pump, a compressor and the like, can be used for industrial large-scale waste gas treatment occasions, and has strong working capacity; the waste gas treatment effect is obvious, and the content of R134a in the air can be reduced to 100 ppm; if necessary, the recovered liquefied waste gas can be gasified and reused, and the method has obvious environmental protection significance and economic value.

Drawings

Fig. 1 is a schematic structural view of the present invention.

Detailed Description

The present invention will be described in further detail with reference to the following examples and the accompanying drawings.

Referring to fig. 1, a structure for recycling volatile gas by low-temperature condensation is formed by connecting a vacuum pump system, a three-stage compressor system and a low-temperature nitrogen condensation heat exchange system; the mixed waste gas is connected with a pumping inlet of a vacuum pump system, passes through a first ball valve 1 and is pumped into a vacuum pump 2; gas exhausted from the vacuum pump 2 enters an air-cooled cooler 7 provided with fins, and enters a buffer tank 8 before compression after the air-cooled cooler 7 is cooled; the inlet of the three-stage compressor system is connected with the outlet of the buffer tank before compression 8, and the gas cooled in the middle of the three-stage compression enters the first sleeve type heat exchanger cooled by cold nitrogen and then is introduced into the high-pressure buffer tank before the cold box 22; the gas in the high-pressure buffer tank 22 in front of the cold box is sent to a low-temperature nitrogen condensation heat exchange system and passes through a heat exchanger group consisting of two sleeve type heat exchangers in two ways, wherein the second sleeve type heat exchanger 26-A and the third sleeve type heat exchanger 26-B of one heat exchanger group are cooled by cold nitrogen; cold sources of a fourth sleeve type heat exchanger 30-A and a fifth sleeve type heat exchanger 30-B of the other heat exchanger group are two paths of reflux gas for completing cooling; all the condensed liquid passes through the first gas-liquid separator 13, the second gas-liquid separator 16, the third gas-liquid separator 20, the fourth gas-liquid separator 27 and the fifth gas-liquid separator 28, is collected in the liquid storage tank 36, and is gasified by the electric heating gasifier 38 connected with the liquid outlet of the liquid storage tank 36 for reuse.

The vacuum pump system comprises a vacuum pump 2, and two electric bypass first proportional valves 3 and second proportional valves 4 which automatically adjust the pressure of a buffer tank 8 before compression and maintain the pressure at micro-positive pressure are connected in front of and behind the vacuum pump 2; the second ball valve 5 and the third ball valve 6 which are opened manually and used for exhausting are arranged at the front and the back of the vacuum pump 2, and are used for directly discharging gas to a buffer tank 8 before compression to normal pressure when the gauge pressure of the evacuated vacuum pump system is positive.

The three-stage compressor system comprises a first-stage compressor 9, a second-stage compressor 11 and a third-stage compressor 14, wherein the inlet of the first-stage compressor 9 is connected with the outlet of a buffer tank 8 before compression, and a first compressor after-cooling device 10, a second compressor after-cooling device 12 and a third compressor after-cooling device 15 are arranged behind the first-stage compressor 9, the second-stage compressor 11 and the third-stage compressor 14; a first gas-liquid separator 13 and a second gas-liquid separator 16 are arranged behind the second-stage compressor 11 and the third-stage compressor 14 and are used for discharging liquid generated by pressurization condensation in time and preventing the compressors from generating liquid impact, cylinder flushing and the like; the liquid outlets of the first gas-liquid separator 13 and the second gas-liquid separator 16 are provided with a first one-way check valve 17 and a second one-way check valve 18, and the outlets of the first one-way check valve 17 and the second one-way check valve 18 are connected with a liquid storage tank 36, so that condensed liquid flows into the liquid storage tank 36 in one way; the gas outlet of the second gas-liquid separator 16 is connected with the tube side inlet of the first sleeve type heat exchanger 19, the compressed gas and the cold nitrogen gas entering from the cold nitrogen gas inlet A are subjected to countercurrent heat exchange and are condensed and then are introduced into a third gas-liquid separator 20, and the gas led out from the gas outlet of the third gas-liquid separator 20 is injected into a front high-pressure buffer tank 22 of the cold box through a fifth ball valve 21.

The working medium gas to be treated in the low-temperature nitrogen condensation heat exchange system passes through a shell pass, the gas for cooling passes through a tube pass, and both paths are countercurrent heat exchange; a cold nitrogen source is connected with the tube side of the third sleeve type heat exchanger 26-B, and nitrogen and treated waste gas which sequentially pass through the third sleeve type heat exchanger 26-B and the second sleeve type heat exchanger 26-A are discharged to the atmosphere; the treated working medium gas is led out from the lower part of a front high-pressure buffer tank 22 of the cold box, passes through a sixth ball valve 23, is divided into two paths, passes through a second needle valve 25 and a first needle valve 24 respectively, and enters a heat exchanger group consisting of a second sleeve type heat exchanger 26-A and a third sleeve type heat exchanger 26-B and a shell side inlet of a heat exchanger group consisting of a fourth sleeve type heat exchanger 30-A and a fifth sleeve type heat exchanger 30-B respectively; the shell side outlets of the second sleeve type heat exchanger 26-A and the fourth sleeve type heat exchanger 30-A are simultaneously connected with a fourth gas-liquid separator 27, the gas outlet of the fourth gas-liquid separator 27 is divided into two paths to be connected with the shell side inlets of the third sleeve type heat exchanger 26-B and the fifth sleeve type heat exchanger 30-B, wherein a low-temperature valve 31 is arranged on a shell side inlet pipeline of the fifth sleeve type heat exchanger 30-B and used for adjusting the gas proportion distributed to the third sleeve type heat exchanger 26-B and the fifth sleeve type heat exchanger 30-B to be consistent with the flow proportion when the gas enters the second sleeve type heat exchanger 26-A and the fourth sleeve type heat exchanger 30-A; similarly, the shell pass outlets of the third sleeve type heat exchanger 26-B and the fifth sleeve type heat exchanger 30-B are simultaneously connected with a fifth gas-liquid separator 28, a gas outlet of the fifth gas-liquid separator 28 passes through a first pressure reducing valve 29 and then is connected with a lower side inlet of the tube pass of the fifth sleeve type heat exchanger 30-B, and the low-temperature backflow gas separated by the fifth gas-liquid separator 28 serves as refrigerant gas and sequentially passes through the fifth sleeve type heat exchanger 30-B and the fourth sleeve type heat exchanger 30-A; the liquid outlets of the third gas-liquid separator 20, the fourth gas-liquid separator 27, and the fifth gas-liquid separator 28 pass through a fourth pressure reducing valve 34, a third pressure reducing valve 33, and a second pressure reducing valve 32, respectively, and then enter a liquid storage tank 36.

An exhaust port of the liquid storage tank 36 is connected with an inlet of a pre-compression buffer tank 8 of the vacuum pump system through a fifth pressure reducing valve 35, and is used for exhausting gas gasified in the liquid storage tank 36 due to external heat transfer to perform compression condensation and low-temperature condensation recovery again; the liquid outlet of the liquid storage tank 36 is connected with the electric heating vaporizer 38 through a sixth pressure reducing valve 37, and when the recovered working medium needs to be recycled, the recycled waste gas can be recycled through the device.

The following description will be made for the principle of the present invention by taking the treatment of the mixed gas of R134a and air in the storage tank as an example:

firstly, checking the pressure in the storage tank, if the pressure is positive, opening the first ball valve 1 and the second ball valve 5, and directly sending the gas in the storage tank to a buffer tank 8 before compression without passing through the vacuum pump 2; after the pressure in the storage tank is reduced to the normal pressure, the second ball valve 5 is closed, the vacuum pump 2, the air-cooled cooler 7, the first-stage compressor 9, the second-stage compressor 11, the third-stage compressor 14, the first one-way check valve 17 and the second one-way check valve 18 are started, and R134a gas in the storage tank is pumped to the buffer tank 8 before compression; for the pressure of buffer tank 8 before maintaining the compression be the pressure-fired, guarantee follow-up compressor job stabilization, automatic proportional control's first proportional valve 3, second proportional valve 4 begin to act: when the upward fluctuation range of the pressure in the buffer tank 8 before compression is large, in order to ensure the regulation speed, the first proportional valve 3 for large-proportion regulation is opened, and a part of the pumped gas circulates in the loop of the first proportional valve 3 and cannot enter the storage tank, so that the pressure in the buffer tank 8 before compression is reduced; when the pressure is reduced to a smaller fluctuation range, in order to prevent the pressure from being reduced too much, the first proportional valve 3 with large proportion adjustment is closed, the second proportional valve 4 with small proportion adjustment is opened, the amount of gas sent to the buffer tank 8 before compression is finely adjusted by the same principle until the pressure in the buffer tank 8 before compression is stabilized to the set micro positive pressure, the adjustment method is the same when the pressure in the buffer tank 8 before compression is reduced, and the first proportional valve 3 and the second proportional valve 4 with electric proportion adjustment are closed, so that more gas after the vacuum pump 2 is introduced into the buffer tank 8 before compression instead of being circulated at the vacuum pump 2.

For the mixed gas of R134a and air, a reciprocating compressor is used, and the mixed gas is compressed to 4MPa in three stages; if the compression ratio is set to 3.42 according to the principle that the compression ratio of each stage is the same, the liquid condensed by the second compressor after-cooling device 12 and the third compressor after-cooling device 15 of the stages due to the pressure rise is discharged to the liquid storage tank 36 through the liquid discharge ports of the first gas-liquid separator 13 and the second gas-liquid separator 16 respectively, so that the link of pressurization and condensation is realized.

The 4MPa gas which is compressed and passes through the second gas-liquid separator 16 is introduced into the first sleeve type heat exchanger 19, is continuously condensed by cold nitrogen gas, and the condensed liquid is decompressed from 4MPa to 1MPa through a fourth decompression valve 34 and is sent into a liquid storage tank 36; the gas is filled into the high-pressure buffer tank 22 before the cold box under the condition that the sixth ball valve 23 is kept closed and the fifth ball valve 21 is kept open; when the R134a in the storage tank to be treated reaches the qualified concentration, the vacuum pump 2, the first-stage compressor 9, the second-stage compressor 11, the third-stage compressor 14 and the fifth ball valve 21 are closed, and the sixth ball valve 23 is opened, so that the gas in the high-pressure buffer tank 22 before the cold box enters the low-temperature nitrogen condensation heat exchange system.

Closing the first needle valve 24 and the low-temperature valve 31, opening the second needle valve 25 and the first pressure reducing valve 29, and introducing cold nitrogen into a cold nitrogen inlet B as shown in FIG. 1, so that the waste gas is condensed in a sleeve type heat exchanger group consisting of the second sleeve type heat exchanger 26-A and the third sleeve type heat exchanger 26-B; for the mixed gas of R134a and air, most of R134a is condensed after heat exchange of the second double pipe heat exchanger 26-A; relatively less R134a condenses out after passing through the third double pipe heat exchanger 26-B, so the fourth gas-liquid separator 27 following the second double pipe heat exchanger 26-a is larger than the fifth gas-liquid separator 28 following the third double pipe heat exchanger 26-B; meanwhile, when the temperature in the third sleeve type heat exchanger 26-B is relatively low, the R134a gas will be desublimated, but if the temperature is not enough to desublimate, the working medium entering the fifth gas-liquid separator 28 still has a small amount of liquid drops, which requires that the fifth gas-liquid separator 28 has strong gas-liquid separation capability to separate out the possible micro liquid drops therein, so as to prevent the liquid accumulation from causing flow problems after long-time operation; the liquid outlets of the fourth gas-liquid separator 27 and the fifth gas-liquid separator 28 are respectively connected with a third reducing valve 33 and a second reducing valve 32, so that the liquid pressure is reduced from 4MPa to 1MPa and then the liquid is sent to a liquid storage tank 36.

The cooled low-temperature gas discharged from the exhaust port of the fifth gas-liquid separator 28 is decompressed from 4MPa to 1atm by a first decompression valve 29, enters a tube pass of a double-tube heat exchanger group consisting of a fourth double-tube heat exchanger 30-a and a fifth double-tube heat exchanger 30-B, and serves as a cooling working medium of the fourth double-tube heat exchanger 30-a and the fifth double-tube heat exchanger 30-B; at this time, the first needle valve 24 can be opened to allow the exhaust gas to enter the fourth double pipe heat exchanger 30-A and the fifth double pipe heat exchanger 30-B; the gas condensed by the fourth shell and tube heat exchanger 30-A also enters the fourth gas-liquid separator 27; the gas outlet of the fourth gas-liquid separator 27 is divided into two parts, one of which is introduced into the third tubular heat exchanger 26-B; the other group is introduced into the fifth double pipe heat exchanger 30-B after passing through the low temperature valve 31, and at the moment, the low temperature valve 31 is adjusted to ensure that the proportion of the gas introduced into the third double pipe heat exchanger 26-B and the fifth double pipe heat exchanger 30-B is the same as the proportion of the gas introduced into the two double pipe heat exchanger groups; the gas-liquid mixture discharged from the shell side of the fifth double pipe heat exchanger 30-B is also introduced into the fifth gas-liquid separator 28, and the obtained gas is returned to the tube side of the fifth double pipe heat exchanger 30-B to be used as a coolant for the next wave of exhaust gas to circulate, so that the link of temperature reduction and condensation is realized.

When the R134a liquid in the liquid storage tank 36 is gasified due to heat leakage or the like, the fifth pressure reducing valve 35 is opened to reduce the gas pressure generated by the gasification from 1MPa to 1atm, and the gas enters the pre-compression buffer tank 8, and is subsequently re-condensed into liquid; when the recovered R134a is to be reused, the sixth pressure reducing valve 37 is opened, and the liquid is fed into the electric heating vaporizer 38 to obtain R134a gas, which is then put into use.

The present embodiment is a further detailed description of the present invention, and it should not be considered that the specific embodiments of the present invention are limited thereto, and a person skilled in the art of the present invention can make several simple deductions or replacements without departing from the concept of the present invention, for example, other cooling working mediums such as liquefied natural gas are used, or a manual refrigeration mode is used to obtain cold energy, such as a steam compression type refrigeration cooling working medium; or different stages of compression, different compression ratios or different forms of compressors, such as centrifugal type, screw type and the like, are adopted in the compression process; or other forms of vacuum pumps or multi-stage parallel evacuation and the like are adopted in the evacuation system; or other heat exchangers such as shell-and-tube heat exchangers, plate heat exchangers, regenerative heat exchangers and the like are adopted in the heat exchange system; or other types of heating equipment, such as water baths, etc., in post-tank liquefaction heating equipment, should be considered within the scope of the utility model as determined by the claims as filed.

Claims

1. The utility model provides a structure of volatile gas is retrieved in low temperature condensation which characterized in that: the system is formed by connecting a vacuum pump system, a three-stage compressor system and a low-temperature nitrogen condensation heat exchange system; the mixed waste gas is connected with a pumping inlet of a vacuum pump system, passes through a first ball valve (1) and is pumped into a vacuum pump (2); gas exhausted from the vacuum pump (2) enters an air-cooled cooler (7) provided with fins, is cooled in the air-cooled cooler (7) and then enters a buffer tank (8) before compression; an inlet of the three-stage compressor system is connected with an outlet of a buffer tank (8) before compression, and gas cooled in the middle of three-stage compression enters a first sleeve type heat exchanger (19) cooled by cold nitrogen and then is introduced into a high-pressure buffer tank (22) before a cold box; gas in a high-pressure buffer tank (22) in front of the cold box is sent to a low-temperature nitrogen condensation heat exchange system and passes through a heat exchanger group consisting of two sleeve type heat exchangers in each path in two paths, wherein a second sleeve type heat exchanger (26-A) and a third sleeve type heat exchanger (26-B) of the heat exchanger group in one path are cooled by cold nitrogen; cold sources of a fourth sleeve type heat exchanger (30-A) and a fifth sleeve type heat exchanger (30-B) of the other heat exchanger group are two paths of reflux gas for completing cooling; all the condensed liquid is collected in a liquid storage tank (36) through a gas-liquid separator and is gasified for reuse through an electric heating gasifier (38) connected with a liquid outlet of the liquid storage tank (36).

2. The structure for low-temperature condensation recovery of volatile gases according to claim 1, characterized in that: the vacuum pump system comprises a vacuum pump (2), wherein the front and the back of the vacuum pump (2) are connected with two automatic adjusting and compressing front buffer tanks (8) for pressure, and a first proportional valve (3) and a second proportional valve (4) of an electric bypass of micro-positive pressure are maintained.

3. The structure for low-temperature condensation recovery of volatile gases according to claim 1, characterized in that: and a second ball valve (5) and a third ball valve (6) which are manually opened and used for exhausting are arranged in front of and behind the vacuum pump (2) and used for directly discharging gas to a buffer tank (8) before compression to normal pressure when the gauge pressure of the evacuated vacuum pump system is positive.

4. The structure for low-temperature condensation recovery of volatile gases according to claim 1, characterized in that: the three-stage compressor system comprises a first-stage compressor (9), a second-stage compressor (11) and a third-stage compressor (14), wherein an inlet of the first-stage compressor (9) is connected with an outlet of a buffer tank (8) before compression, and a first-compressor after-cooling device (10), a second-compressor after-cooling device (12) and a third-compressor after-cooling device (15) are arranged behind the first-stage compressor (9), the second-stage compressor (11) and the third-stage compressor (14); a first gas-liquid separator (13) and a second gas-liquid separator (16) are arranged behind the second-stage compressor (11) and the third-stage compressor (14); the liquid discharge ports of the first gas-liquid separator (13) and the second gas-liquid separator (16) are provided with a first one-way check valve (17) and a second one-way check valve (18), and the outlets of the first one-way check valve (17) and the second one-way check valve (18) are connected with a liquid storage tank (36).

5. The structure for low-temperature condensation recovery of volatile gases according to claim 4, characterized in that: and a gas outlet of the second gas-liquid separator (16) is connected with a tube pass inlet of the first sleeve type heat exchanger (19), compressed gas and cold nitrogen entering from the cold nitrogen inlet A are subjected to countercurrent heat exchange and are condensed and then are introduced into a third gas-liquid separator (20), and gas led out from a gas outlet of the third gas-liquid separator (20) is injected into a front high-pressure buffer tank (22) of the cold box through a fifth ball valve (21).

6. The structure for low-temperature condensation recovery of volatile gases according to claim 5, wherein: the working medium gas to be treated in the low-temperature nitrogen condensation heat exchange system passes through a shell pass, the gas for cooling passes through a tube pass, and both paths are countercurrent heat exchange; a cold nitrogen source is connected with the tube side of the third sleeve type heat exchanger (26-B), and nitrogen and treated waste gas which sequentially pass through the third sleeve type heat exchanger (26-B) and the second sleeve type heat exchanger (26-A) are discharged to the atmosphere; the treated working medium gas is led out from the lower part of a front high-pressure buffer tank (22) of the cold box, passes through a sixth ball valve (23), is divided into two paths, passes through a second needle valve (25) and a first needle valve (24), and enters a shell pass inlet of a heat exchanger group consisting of a second sleeve type heat exchanger (26-A) and a third sleeve type heat exchanger (26-B) and a shell pass inlet of a heat exchanger group consisting of a fourth sleeve type heat exchanger (30-A) and a fifth sleeve type heat exchanger (30-B); the shell-side outlets of the second sleeve-type heat exchanger (26-A) and the fourth sleeve-type heat exchanger (30-A) are simultaneously connected with a fourth gas-liquid separator (27), the gas outlet of the fourth gas-liquid separator (27) is divided into two paths to be connected with the shell-side inlets of the third sleeve-type heat exchanger (26-B) and the fifth sleeve-type heat exchanger (30-B), and a low-temperature valve (31) is arranged on the shell-side inlet pipeline of the fifth sleeve-type heat exchanger (30-B); similarly, the shell pass outlets of the third sleeve type heat exchanger (26-B) and the fifth sleeve type heat exchanger (30-B) are simultaneously connected with a fifth gas-liquid separator (28), the gas outlet of the fifth gas-liquid separator (28) is connected with the lower side inlet of the tube pass of the fifth sleeve type heat exchanger (30-B) after passing through a first reducing valve (29), and the low-temperature backflow gas separated by the fifth gas-liquid separator (28) is used as refrigerant gas and sequentially passes through the fifth sleeve type heat exchanger (30-B) and the fourth sleeve type heat exchanger (30-A).

7. The structure for low-temperature condensation recovery of volatile gases according to claim 6, characterized in that: liquid outlets of the third gas-liquid separator (20), the fourth gas-liquid separator (27) and the fifth gas-liquid separator (28) respectively pass through a fourth reducing valve (34), a third reducing valve (33) and a second reducing valve (32) and then enter a liquid storage tank (36).

8. The structure for low-temperature condensation recovery of volatile gases according to claim 1, characterized in that: an exhaust port of the liquid storage tank (36) is connected with an inlet of a buffer tank (8) before compression of the vacuum pump system through a fifth pressure reducing valve (35); the liquid outlet of the liquid storage tank (36) is connected with the electric heating vaporizer (38) through a sixth pressure reducing valve (37).