CN113883826B - System for low temperature condensation retrieves volatile gas - Google Patents
System for low temperature condensation retrieves volatile gas Download PDFInfo
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- CN113883826B CN113883826B CN202111157908.XA CN202111157908A CN113883826B CN 113883826 B CN113883826 B CN 113883826B CN 202111157908 A CN202111157908 A CN 202111157908A CN 113883826 B CN113883826 B CN 113883826B
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- 238000009833 condensation Methods 0.000 title claims abstract description 29
- 230000005494 condensation Effects 0.000 title claims abstract description 29
- 239000007788 liquid Substances 0.000 claims abstract description 129
- 239000007789 gas Substances 0.000 claims abstract description 113
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims abstract description 90
- 229910052757 nitrogen Inorganic materials 0.000 claims abstract description 45
- 238000007906 compression Methods 0.000 claims abstract description 38
- 230000006835 compression Effects 0.000 claims abstract description 37
- 238000003860 storage Methods 0.000 claims abstract description 32
- 238000001816 cooling Methods 0.000 claims abstract description 28
- 239000002912 waste gas Substances 0.000 claims abstract description 13
- 238000005485 electric heating Methods 0.000 claims abstract description 8
- 239000010812 mixed waste Substances 0.000 claims abstract description 4
- 238000011084 recovery Methods 0.000 claims description 10
- 238000010992 reflux Methods 0.000 claims description 3
- 239000003507 refrigerant Substances 0.000 claims description 3
- 230000000694 effects Effects 0.000 abstract description 5
- 238000004064 recycling Methods 0.000 abstract description 5
- 238000000034 method Methods 0.000 description 11
- 239000012855 volatile organic compound Substances 0.000 description 9
- 230000007613 environmental effect Effects 0.000 description 4
- 238000002309 gasification Methods 0.000 description 3
- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 3
- 239000006200 vaporizer Substances 0.000 description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- RAHZWNYVWXNFOC-UHFFFAOYSA-N Sulphur dioxide Chemical compound O=S=O RAHZWNYVWXNFOC-UHFFFAOYSA-N 0.000 description 2
- 238000009835 boiling Methods 0.000 description 2
- 239000002826 coolant Substances 0.000 description 2
- 230000006837 decompression Effects 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 238000010926 purge Methods 0.000 description 2
- 238000005057 refrigeration Methods 0.000 description 2
- 241000282414 Homo sapiens Species 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
- 238000003915 air pollution Methods 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 238000011010 flushing procedure Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 231100000252 nontoxic Toxicity 0.000 description 1
- 230000003000 nontoxic effect Effects 0.000 description 1
- 239000003973 paint Substances 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 239000007921 spray Substances 0.000 description 1
- 238000000859 sublimation Methods 0.000 description 1
- 230000008022 sublimation Effects 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
- F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
- F25J1/02—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures requiring the use of refrigeration, e.g. of helium or hydrogen ; Details and kind of the refrigeration system used; Integration with other units or processes; Controlling aspects of the process
- F25J1/0203—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures requiring the use of refrigeration, e.g. of helium or hydrogen ; Details and kind of the refrigeration system used; Integration with other units or processes; Controlling aspects of the process using a single-component refrigerant [SCR] fluid in a closed vapor compression cycle
- F25J1/0207—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures requiring the use of refrigeration, e.g. of helium or hydrogen ; Details and kind of the refrigeration system used; Integration with other units or processes; Controlling aspects of the process using a single-component refrigerant [SCR] fluid in a closed vapor compression cycle as at least a three level SCR refrigeration cascade
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
- F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
- F25J1/02—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures requiring the use of refrigeration, e.g. of helium or hydrogen ; Details and kind of the refrigeration system used; Integration with other units or processes; Controlling aspects of the process
- F25J1/0243—Start-up or control of the process; Details of the apparatus used; Details of the refrigerant compression system used
- F25J1/0244—Operation; Control and regulation; Instrumentation
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
- F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
- F25J1/02—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures requiring the use of refrigeration, e.g. of helium or hydrogen ; Details and kind of the refrigeration system used; Integration with other units or processes; Controlling aspects of the process
- F25J1/0243—Start-up or control of the process; Details of the apparatus used; Details of the refrigerant compression system used
- F25J1/0257—Construction and layout of liquefaction equipments, e.g. valves, machines
- F25J1/0262—Details of the cold heat exchange system
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
- F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
- F25J1/02—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures requiring the use of refrigeration, e.g. of helium or hydrogen ; Details and kind of the refrigeration system used; Integration with other units or processes; Controlling aspects of the process
- F25J1/0243—Start-up or control of the process; Details of the apparatus used; Details of the refrigerant compression system used
- F25J1/0279—Compression of refrigerant or internal recycle fluid, e.g. kind of compressor, accumulator, suction drum etc.
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
- F25J2270/00—Refrigeration techniques used
- F25J2270/60—Closed external refrigeration cycle with single component refrigerant [SCR], e.g. C1-, C2- or C3-hydrocarbons
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- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Mechanical Engineering (AREA)
- Thermal Sciences (AREA)
- General Engineering & Computer Science (AREA)
- Separation By Low-Temperature Treatments (AREA)
Abstract
A system for recycling volatile gases through 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 evacuating inlet of the vacuum pump system and is pumped into the vacuum pump; the gas discharged 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 subjected to three-stage compression and intermediate cooling enters the double-pipe heat exchanger cooled by cold nitrogen 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 the heat exchanger groups in two paths, wherein one path of heat exchanger group is cooled by cold nitrogen; the cold source of the other heat exchanger group is two paths of reverse flow gas for completing cooling; all condensed liquid is collected in a liquid storage tank and gasified by an electric heating gasifier for reuse; the invention can be used for the occasion of industrial large-scale waste gas treatment, and has obvious treatment effect.
Description
Technical Field
The invention belongs to the technical field of volatile gas recovery, and particularly relates to a system for recovering volatile gas by low-temperature condensation.
Background
Air pollution is one of the main environmental problems facing human beings at present, and along with the continuous improvement of environmental protection requirements, the treatment of volatile gases in the air, particularly Volatile Organic Compounds (VOCs), is also continuously receiving attention from various industrial departments. In general, there are two approaches to the treatment of volatile gases: firstly, controlling the generation of volatile gas from a source; and secondly, recycling or destroying volatile gases discharged in the production process. The first method adopts an environment-friendly production method from the source, has the effect of optimally controlling the emission of VOCs, but the current industrial state does not have the condition of large-scale environment-friendly reconstruction of the industrial field. In recent years, effective VOCs recovery techniques have been adopted for different fields, and have been attracting attention because of the considerable economic and social benefits that they can produce.
Among the methods for recovering or destroying volatile gases, the condensation method is more classical, which includes cooling condensation and pressurizing condensation, both of which are separated by utilizing the difference in boiling point of different components in the exhaust gas at the same pressure. Because VOCs waste gas is often composed of organic matters and air, and the atmospheric boiling point of most organic matters and inorganic matters such as sulfur dioxide, nitrogen oxides and the like is higher than the air liquefying temperature (90.3K), the VOCs waste gas can be separated by adopting a condensing method; the storage temperature of the low-temperature liquid nitrogen under normal pressure is 77.3K, the low-temperature liquid nitrogen is low in price, wide in source, nontoxic, harmless and pollution-free, and can be used in the industrial field on a large scale, so that the low-temperature liquid nitrogen is often used as a coolant for low-temperature condensation.
Chinese patent (publication No. 104501485B) discloses a method for recovering freon by condensing liquid nitrogen, which blows the trapped freon into a cold box pipeline by means of nitrogen pressure after gasification of liquid nitrogen, then liquefies and collects freon by utilizing cold energy of liquid nitrogen, and the heated and gasified nitrogen is adsorbed by activated carbon and then discharged to the atmosphere. Although the condensation recovery device in the form can well recover freon, power equipment is not needed, and the investment is small; however, in small-sized equipment, the recovery of low-content freon in a small space can only be satisfied by utilizing liquid nitrogen gasification, and effective purging of a large amount of freon in a large space is difficult to complete, for example, the recovery and utilization of gaseous freon in large-sized freon refrigerating systems, large-sized storage tanks and other equipment are difficult to complete; the effect cannot be exerted in occasions such as large-scale factory buildings, paint spray houses, oil and gas reservoirs, laboratory dispersion volatile gas purification and the like; furthermore, the mere use of vaporized nitrogen to blow off the exhaust gas requires that the target device have at least a pair of inlet and outlet ports, and such purging methods cannot be used with single port devices commonly used in the industry.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention aims to provide a system for recycling volatile gases through low-temperature condensation, which is applicable to VOCs and various high-boiling-point volatile gases and has high universality; the method can be used for large-scale waste gas treatment in the industrial field, has the advantages of large waste gas treatment capacity and good waste gas treatment effect, and the recycled liquefied gas can be gasified and recycled, so that the environmental protection performance is outstanding.
In order to achieve the above purpose, the invention adopts the following technical scheme:
A system for recycling volatile gases through 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 evacuating inlet of the vacuum pump system and is pumped into the vacuum pump 2 after passing through the first ball valve 1; the gas discharged from the vacuum pump 2 enters an air-cooled cooler 7 with ribs, and enters a buffer tank 8 before compression after being cooled in the air-cooled cooler 7; the inlet of the three-stage compressor system is connected with the outlet of the pre-compression buffer tank 8, and the gas subjected to three-stage compression and intermediate cooling enters the first double-pipe heat exchanger 19 cooled by cold nitrogen and then is introduced into the pre-cold-box high-pressure buffer tank 22; the gas in the high-pressure buffer tank 22 before the cold box is sent to a low-temperature nitrogen condensation heat exchange system, and the gas is divided into two paths to pass through a heat exchanger group consisting of two double-pipe heat exchangers, wherein the second double-pipe heat exchanger 26-A and the third double-pipe heat exchanger 26-B of one path of heat exchanger group are cooled by cold nitrogen; the cold sources of the fourth sleeve heat exchanger 30-A and the fifth sleeve heat exchanger 30-B of the other heat exchanger group are reflux gas for completing cooling; all condensed liquid is collected in the liquid storage tank 36 through the gas-liquid separator and gasified for reuse by the electric heating gasifier 38 connected to the liquid discharge port of the liquid storage tank 36.
The vacuum pump system comprises a vacuum pump 2, and the front and the back of the vacuum pump 2 are connected with a first proportional valve 3 and a second proportional valve 4 which are used for automatically adjusting the pressure of a buffer tank 8 before compression and maintaining the electric bypass of micro positive pressure.
The front and the back of the vacuum pump 2 are respectively provided with a second ball valve 5 and a third ball valve 6 which are manually opened for exhausting, and the second ball valve and the third ball valve are used for directly exhausting gas to the 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 an inlet of the first-stage compressor 9 is connected with an outlet of a pre-compression buffer tank 8, and a first compressor post-cooling device 10, a second compressor post-cooling device 12 and a third compressor post-cooling device 15 are arranged behind the first-stage compressor 9, the second-stage compressor 11 and the third-stage compressor 14; the first gas-liquid separator 13 and the 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.
The gas outlet of the second gas-liquid separator 16 is connected with the tube side inlet of the first double pipe heat exchanger 19, the compressed gas and the cold nitrogen entering from the cold nitrogen inlet A are subjected to countercurrent heat exchange and condensation, then are introduced into the third gas-liquid separator 20, and the gas led out from the gas outlet of the third gas-liquid separator 20 is injected into the front high-pressure buffer tank 22 of the cold box through the fifth ball valve 21.
Working medium gas processed in the low-temperature nitrogen condensation heat exchange system passes through a shell side and is used for cooling a gas passing tube side, and the two paths are countercurrent heat exchange; the cold nitrogen source is connected with the tube side of the third double-pipe heat exchanger 26-B, and the nitrogen and the treated waste gas which sequentially pass through the third double-pipe heat exchanger 26-B and the second double-pipe heat exchanger 26-A are discharged to the atmosphere; the processed working medium gas is led out from the lower part of the cold box front high-pressure buffer tank 22, is divided into two paths by a sixth ball valve 23, and respectively 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 through a second needle valve 25 and a first needle valve 24; the shell side outlets of the second sleeve heat exchanger 26-A and the fourth sleeve heat exchanger 30-A are simultaneously connected with the fourth gas-liquid separator 27, the gas outlet of the fourth gas-liquid separator 27 is connected with the shell side inlets of the third sleeve heat exchanger 26-B and the fifth sleeve heat exchanger 30-B in two ways, and a low temperature valve 31 is arranged on the shell side inlet pipeline of the fifth sleeve heat exchanger 30-B; the shell side outlets of the third sleeve heat exchanger 26-B and the fifth sleeve heat exchanger 30-B are simultaneously connected with the fifth gas-liquid separator 28, the gas outlet of the fifth gas-liquid separator 28 is connected with the inlet at the lower side of the tube side of the fifth sleeve heat exchanger 30-B after passing through the first pressure reducing valve 29, and the low Wen Fanliu gas separated by the fifth gas-liquid separator 28 is used as refrigerant gas to pass through the fifth sleeve heat exchanger 30-B and the fourth sleeve heat exchanger 30-A in sequence.
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 pressure reducing valve 34, a third pressure reducing valve 33 and a second pressure 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 pressure reducing valve 35; the drain port of the liquid tank 36 is connected to an electric heating vaporizer 38 via a sixth pressure reducing valve 37.
Compared with the prior art, the invention has the following advantages:
the whole process is a physical process, does not involve adsorption, absorption and various chemical treatment processes, is suitable for VOCs (volatile organic compounds) including freon and various high-boiling-point volatile gases, and has high universality; the fluid machinery with a vacuum pump, a compressor and the like can be used for the occasion of industrial large-scale waste gas treatment, and has strong working capacity; the waste gas treatment effect is obvious, and the content of R134a in the air can be reduced to 100ppm; if necessary, the recovered liquefied waste gas can be gasified and reused, and has obvious environmental protection significance and economic value.
Drawings
Fig. 1 is a schematic diagram of the system of the present invention.
Detailed Description
The present invention will be described in further detail with reference to examples and drawings.
Referring to fig. 1, a system for recycling volatile gases 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 evacuating inlet of the vacuum pump system and is pumped into the vacuum pump 2 after passing through the first ball valve 1; the gas discharged from the vacuum pump 2 enters an air-cooled cooler 7 with ribs, 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 pre-compression buffer tank 8, and the gas subjected to three-stage compression and intermediate cooling enters the first double-pipe heat exchanger 19 cooled by cold nitrogen and then is introduced into the pre-cold-box high-pressure buffer tank 22; the gas in the high-pressure buffer tank 22 before the cold box is sent to a low-temperature nitrogen condensation heat exchange system, and the gas is divided into two paths to pass through a heat exchanger group consisting of two double-pipe heat exchangers, wherein the second double-pipe heat exchanger 26-A and the third double-pipe heat exchanger 26-B of one path of heat exchanger group are cooled by cold nitrogen; the cold sources of the fourth sleeve heat exchanger 30-A and the fifth sleeve heat exchanger 30-B of the other heat exchanger group are two paths of reflux gases for completing cooling; all 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 for reuse by the electric heating gasifier 38 connected with the liquid discharge port of the liquid storage tank 36.
The vacuum pump system comprises a vacuum pump 2, and the front and the back of the vacuum pump 2 are connected with a first proportional valve 3 and a second proportional valve 4 which are used for automatically adjusting the pressure of a buffer tank 8 before compression and maintaining the electric bypass of micro positive pressure; the front and the back of the vacuum pump 2 are respectively provided with a second ball valve 5 and a third ball valve 6 which are manually opened for exhausting gas, and the second ball valve and the third ball valve are used for directly exhausting gas to the 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 an inlet of the first-stage compressor 9 is connected with an outlet of a pre-compression buffer tank 8, and a first compressor post-cooling device 10, a second compressor post-cooling device 12 and a third compressor post-cooling device 15 are arranged behind the first-stage compressor 9, the second-stage compressor 11 and the third-stage compressor 14; the first gas-liquid separator 13 and the second gas-liquid separator 16 are arranged behind the second-stage compressor 11 and the third-stage compressor 14 and are used for timely discharging liquid generated by pressurizing and condensing so as to prevent the compressor from generating phenomena such as liquid impact, cylinder flushing and the like; 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 the liquid storage tank 36 so that condensed liquid flows into the liquid storage tank 36 unidirectionally; the gas outlet of the second gas-liquid separator 16 is connected with the tube side inlet of the first double pipe heat exchanger 19, the compressed gas and cold nitrogen entering from the cold nitrogen inlet A are subjected to countercurrent heat exchange and condensation, then the compressed gas is introduced into the third gas-liquid separator 20, and the gas led out from the gas outlet of the third gas-liquid separator 20 is injected into the high-pressure buffer tank 22 before the cold box through the fifth ball valve 21.
Working medium gas processed in the low-temperature nitrogen condensation heat exchange system passes through a shell side and is used for cooling a gas passing tube side, and the two paths are countercurrent heat exchange; the cold nitrogen source is connected with the tube side of the third double-pipe heat exchanger 26-B, and the nitrogen and the treated waste gas which sequentially pass through the third double-pipe heat exchanger 26-B and the second double-pipe heat exchanger 26-A are discharged to the atmosphere; the processed working medium gas is led out from the lower part of the cold box front high-pressure buffer tank 22, is divided into two paths by a sixth ball valve 23, and respectively 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 through a second needle valve 25 and a first needle valve 24; the shell side outlets of the second sleeve heat exchanger 26-A and the fourth sleeve heat exchanger 30-A are simultaneously connected with the fourth gas-liquid separator 27, the gas outlet of the fourth gas-liquid separator 27 is connected with the shell side inlets of the third sleeve heat exchanger 26-B and the fifth sleeve heat exchanger 30-B in two paths, wherein a low temperature valve 31 is arranged on the shell side inlet pipeline of the fifth sleeve heat exchanger 30-B and is used for adjusting the proportion of gas distributed to the third sleeve heat exchanger 26-B and the fifth sleeve heat exchanger 30-B to be consistent with the proportion of flow entering the second sleeve heat exchanger 26-A and the fourth sleeve heat exchanger 30-A; similarly, the outlets of the shell passes of the third double-pipe heat exchanger 26-B and the fifth double-pipe heat exchanger 30-B are simultaneously connected with the fifth gas-liquid separator 28, the gas outlet of the fifth gas-liquid separator 28 is connected with the inlet at the lower side of the tube pass of the fifth double-pipe heat exchanger 30-B after passing through the first pressure reducing valve 29, and the low Wen Fanliu gas separated by the fifth gas-liquid separator 28 is used as refrigerant gas to pass through the fifth double-pipe heat exchanger 30-B and the fourth double-pipe heat exchanger 30-A in sequence; 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.
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 pressure reducing valve 35, and is used for exhausting the gasified gas in the liquid storage tank 36 due to the external heat transfer to perform compression condensation and low-temperature condensation recovery again; the liquid discharge port of the liquid storage tank 36 is connected to an electric heating vaporizer 38 via a sixth pressure reducing valve 37, and when the recovered working medium needs to be reused, the recovered exhaust gas can be reused by the apparatus.
The principle of the present invention will be described below by taking the example of treating a mixed gas of R134a and air in a tank:
Firstly, checking the pressure in a storage tank, if the pressure is positive, opening a first ball valve 1 and a second ball valve 5, and directly sending the gas in the storage tank to a buffer tank 8 before compression without a vacuum pump 2; after the pressure in the storage tank is reduced to 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; in order to maintain the pressure of the buffer tank 8 to be micro positive pressure before compression, the working stability of the subsequent compressor is ensured, and the first proportional valve 3 and the second proportional valve 4 with automatic proportional adjustment start to act: when the upward fluctuation range of the pressure in the pre-compression buffer tank 8 is large, the first proportional valve 3 for large proportion adjustment is opened to ensure the adjustment speed, and a part of the pumped gas circulates in the loop where the first proportional valve 3 is located and does not enter the storage tank, so that the pressure in the pre-compression buffer tank 8 is reduced; when the pressure in the buffer tank 8 is reduced, the first proportional valve 3 and the second proportional valve 4 which are adjusted in an electric mode are closed, so that more gas after the vacuum pump 2 is introduced into the buffer tank 8 before compression rather than circulated at the vacuum pump 2.
For the mixed gas of R134a and air, a reciprocating compressor is used to compress the mixed gas 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 due to the pressure rise between stages 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 step of pressurizing and condensing is realized.
4MPa gas which is compressed and passes through the second gas-liquid separator 16 is introduced into the first double-pipe heat exchanger 19, is continuously condensed by cold nitrogen, and condensed liquid is decompressed from 4MPa to 1MPa through the fourth decompression valve 34 and is sent into the liquid storage tank 36; the gas is filled into the cold box front high-pressure buffer tank 22 under the condition that the sixth ball valve 23 is kept closed and the fifth ball valve 21 is opened; when R134a in the storage tank to be treated reaches the acceptable 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, the sixth ball valve 23 is opened, and 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 the cold nitrogen inlet B as shown in figure 1, so that the waste gas is condensed in a double pipe heat exchanger group consisting of the second double pipe heat exchanger 26-A and the third double pipe heat exchanger 26-B; for the mixed gas of R134a and air, most of R134a condenses out after passing through the 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 that 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 double pipe heat exchanger 26-B is relatively low, the R134a gas will be sublimated, but if the temperature is insufficient to enable the sublimation to occur, the working medium entering the fifth gas-liquid separator 28 will still have a small amount of liquid drops, which requires the fifth gas-liquid separator 28 to have a strong gas-liquid separation capability so as to separate the micro liquid drops possibly carried in the fifth gas-liquid separator, so that the problem of flow caused by long-time running liquid accumulation is prevented; the liquid outlets of the fourth gas-liquid separator 27 and the fifth gas-liquid separator 28 are respectively connected with a third pressure reducing valve 33 and a second pressure reducing valve 32, so that the liquid pressure is reduced from 4MPa to 1MPa and then 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 to 1atm from 4MPa through the first decompression valve 29, enters the tube pass of the double-pipe heat exchanger group consisting of the fourth double-pipe heat exchanger 30-A and the fifth double-pipe heat exchanger 30-B, and serves as cooling working media of the fourth double-pipe heat exchanger 30-A and the fifth double-pipe heat exchanger 30-B; at this time, the first needle valve 24 may be opened to allow the exhaust gas to enter the fourth and fifth double pipe heat exchangers 30-a and 30-B; the gas condensed from the fourth double pipe 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, wherein one part is led into the third double pipe heat exchanger 26-B; the other group is introduced into the fifth double pipe heat exchanger 30-B through the low temperature valve 31, and at this time, the low temperature valve 31 should be adjusted so that the ratio of the gas introduced into the third double pipe heat exchanger 26-B to the fifth double pipe heat exchanger 30-B is the same as the ratio 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 as the coolant circulation of the next wave exhaust gas, thus realizing the link of cooling and condensing.
When the R134a liquid in the liquid storage tank 36 is gasified due to factors such as heat leakage, the fifth pressure reducing valve 35 is opened to reduce the pressure of the gas 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 for use.
The present embodiment is further described in detail, and it is not to be construed that the specific embodiments of the present invention are limited thereto, and it is possible for those skilled in the art to make several simple deductions or substitutions without departing from the spirit of the present invention, for example, using other cooling working media such as lng, or obtaining cold energy by manual refrigeration, such as using vapor compression refrigeration cooling working media; or compression with different stages, different compression ratios, or compressors with different forms, such as centrifugal type, screw type, etc. are adopted in the compression process; or the other forms of vacuum pumps are adopted in the evacuation system or the forms of multistage parallel evacuation and the like are adopted; or other heat exchangers are adopted in the heat exchange system, such as a shell-and-tube heat exchanger, a plate heat exchanger, a heat accumulating type heat exchanger and the like; or other types of heating devices, such as water baths, etc., may be used in the post-tank liquefaction heating device and are considered to be within the scope of the invention as defined by the claims that issue.
Claims (6)
1. A system for cryocondensing and recovering volatile gases, characterized by: the system consists of a vacuum pump system, a three-stage compressor system and a low-temperature nitrogen condensation heat exchange system which are connected; the mixed waste gas is connected with an evacuating inlet of the vacuum pump system and is pumped into the vacuum pump (2) after passing through the first ball valve (1); the gas discharged from the vacuum pump (2) enters an air-cooled cooler (7) with ribs, and enters a buffer tank (8) before compression after being cooled in the air-cooled cooler (7); the inlet of the three-stage compressor system is connected with the outlet of the pre-compression buffer tank (8), and gas subjected to three-stage compression intermediate cooling enters the first double-pipe heat exchanger (19) cooled by cold nitrogen and then is introduced into the pre-cold-box high-pressure buffer tank (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 the gas passes through two heat exchanger groups formed by two double-pipe heat exchangers in each path, wherein the second double-pipe heat exchanger (26-A) and the third double-pipe heat exchanger (26-B) of one heat exchanger group are cooled by cold nitrogen; the cold sources of the fourth double-pipe heat exchanger (30-A) and the fifth double-pipe heat exchanger (30-B) of the other heat exchanger group are two paths of reflux gases for completing cooling; all condensed liquid is collected in a liquid storage tank (36) through a gas-liquid separator and gasified for reuse through an electric heating gasifier (38) connected with a liquid outlet of the liquid storage tank (36);
The vacuum pump system comprises a vacuum pump (2), and the front and the back of the vacuum pump (2) are connected with a first proportional valve (3) and a second proportional valve (4) which are used for automatically adjusting the pressure of a buffer tank (8) before compression and maintaining the electric bypass at micro positive pressure;
The vacuum pump (2) is provided with a second ball valve (5) and a third ball valve (6) which are manually opened before and after exhausting, and the second ball valve and the third ball valve are used for directly exhausting gas to the buffer tank (8) before compression to normal pressure when the gauge pressure of the evacuated vacuum pump system is positive.
2. A system for cryocondensing recovery of volatile gases in accordance with claim 1 wherein: 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 pre-compression buffer tank (8), and a first compressor post-cooling device (10), a second compressor post-cooling device (12) and a third compressor post-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 draining 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).
3. A system for cryocondensing recovery of volatile gases in accordance with claim 2 wherein: the gas outlet of the second gas-liquid separator (16) is connected with the tube side inlet of the first double-tube heat exchanger (19), the compressed gas and cold nitrogen entering from the cold nitrogen inlet A are subjected to countercurrent heat exchange and condensation, then the compressed gas is introduced into the third gas-liquid separator (20), and the gas led out from the gas outlet of the third gas-liquid separator (20) is injected into the high-pressure buffer tank (22) in front of the cold box through the fifth ball valve (21).
4. A system for cryocondensing recovery of volatile gases as in claim 3 wherein: working medium gas processed in the low-temperature nitrogen condensation heat exchange system passes through a shell side and is used for cooling a gas passing tube side, and the two paths are countercurrent heat exchange; the cold nitrogen source is connected with the tube side of the third double-pipe heat exchanger (26-B), and the nitrogen and the treated waste gas which sequentially pass through the third double-pipe heat exchanger (26-B) and the second double-pipe heat exchanger (26-A) are discharged to the atmosphere; the processed working medium gas is led out from the lower part of a high-pressure buffer tank (22) in front of the cold box, is divided into two paths through a sixth ball valve (23), and respectively enters a heat exchanger group consisting of a second double-pipe heat exchanger (26-A) and a third double-pipe heat exchanger (26-B) and a shell side inlet of a heat exchanger group consisting of a fourth double-pipe heat exchanger (30-A) and a fifth double-pipe heat exchanger (30-B) through a second needle valve (25) and a first needle valve (24); the shell side outlets of the second double-pipe heat exchanger (26-A) and the fourth double-pipe heat exchanger (30-A) are simultaneously connected with a fourth gas-liquid separator (27), and the gas outlet of the fourth gas-liquid separator (27) is connected with the shell side inlets of the third double-pipe heat exchanger (26-B) and the fifth double-pipe heat exchanger (30-B) in two ways, wherein a low temperature valve (31) is arranged on the shell side inlet pipeline of the fifth double-pipe heat exchanger (30-B); the third double pipe heat exchanger (26-B) and the shell side outlet of the fifth double pipe heat exchanger (30-B) are connected with the fifth gas-liquid separator (28) at the same time, the gas outlet of the fifth gas-liquid separator (28) is connected with the inlet at the lower side of the tube side of the fifth double pipe heat exchanger (30-B) after passing through the first pressure reducing valve (29), and the low Wen Fanliu gas separated by the fifth gas-liquid separator (28) is used as refrigerant gas to pass through the fifth double pipe heat exchanger (30-B) and the fourth double pipe heat exchanger (30-A) in sequence.
5. A system for cryocondensing a recovered volatile gas as in claim 4, wherein: 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 pressure reducing valve (34), a third pressure reducing valve (33) and a second pressure reducing valve (32) and then enter a liquid storage tank (36).
6. A system for cryocondensing recovery of volatile gases in accordance with claim 1 wherein: 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 pressure reducing valve (35); the liquid outlet of the liquid storage tank (36) is connected with an electric heating gasifier (38) through a sixth pressure reducing valve (37).
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