CN111521454A - Enrichment and preseparation system for VOCs in atmosphere - Google Patents

Enrichment and preseparation system for VOCs in atmosphere Download PDF

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Publication number
CN111521454A
CN111521454A CN202010488217.7A CN202010488217A CN111521454A CN 111521454 A CN111521454 A CN 111521454A CN 202010488217 A CN202010488217 A CN 202010488217A CN 111521454 A CN111521454 A CN 111521454A
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control valve
cold trap
flow controller
gas
gas flow
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徐强
余超
宋新
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Suzhou Abies Precision Instruments Co ltd
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Suzhou Abies Precision Instruments Co ltd
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N1/00—Sampling; Preparing specimens for investigation
    • G01N1/02—Devices for withdrawing samples
    • G01N1/22—Devices for withdrawing samples in the gaseous state
    • G01N1/2202—Devices for withdrawing samples in the gaseous state involving separation of sample components during sampling
    • G01N1/2214—Devices for withdrawing samples in the gaseous state involving separation of sample components during sampling by sorption
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N1/00—Sampling; Preparing specimens for investigation
    • G01N1/02—Devices for withdrawing samples
    • G01N1/22—Devices for withdrawing samples in the gaseous state
    • G01N1/2202—Devices for withdrawing samples in the gaseous state involving separation of sample components during sampling
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N1/00—Sampling; Preparing specimens for investigation
    • G01N1/02—Devices for withdrawing samples
    • G01N1/22—Devices for withdrawing samples in the gaseous state
    • G01N1/2273—Atmospheric sampling
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N1/00—Sampling; Preparing specimens for investigation
    • G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
    • G01N1/40—Concentrating samples
    • G01N1/4022—Concentrating samples by thermal techniques; Phase changes
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N1/00—Sampling; Preparing specimens for investigation
    • G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
    • G01N1/40—Concentrating samples
    • G01N1/405—Concentrating samples by adsorption or absorption
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N1/00—Sampling; Preparing specimens for investigation
    • G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
    • G01N1/40—Concentrating samples
    • G01N1/4022—Concentrating samples by thermal techniques; Phase changes
    • G01N2001/4033—Concentrating samples by thermal techniques; Phase changes sample concentrated on a cold spot, e.g. condensation or distillation

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Abstract

The invention discloses an enrichment and preseparation system for VOCs in atmosphere, which comprises a sampling device, a dewatering device, an enrichment and preseparation device and a sampling device; the enrichment and pre-separation device comprises a second cold trap, a third cold trap, a fourth cold trap, a second gas flow controller and a third gas flow controller. The enrichment and pre-separation system for VOCs in the atmosphere provided by the invention can realize synchronous adsorption concentration and preliminary separation of VOCs in the sample gas, and has high adsorption efficiency; the VOCs subjected to preliminary adsorption and separation are respectively classified and collected through different desorption and collection passages, so that the pre-separation of various VOCs is realized; and the self-cleaning of the equipment can be realized, the operation is simple, and no additional auxiliary device is needed.

Description

Enrichment and preseparation system for VOCs in atmosphere
Technical Field
The invention relates to the technical field of atmospheric environment detection equipment, in particular to an enrichment and preseparation system for VOCs in atmosphere.
Background
Volatile Organic Compounds (VOCs) refer to organic compounds with saturated vapor pressure of more than 70Pa at normal temperature and boiling point of 260 ℃ below under normal pressure in China, or all organic compounds with corresponding volatility and vapor pressure of more than or equal to 10Pa at 20 ℃. Generally, the main components thereof include hydrocarbons, oxygen hydrocarbons, halogen-containing hydrocarbons, nitrogen and sulfur hydrocarbons, low-boiling polycyclic aromatic hydrocarbons and the like. VOCs can cause respiratory diseases, acute poisoning can be caused under the action of high-concentration pollutants, and secondary pollutants are generated through photochemical reaction under the action of sunlight to form smoke pollution. VOCs are characterized by lower evaporation temperature than water and are mainly produced from industrial waste gas, automobile exhaust, house decoration, device spray paint and the like.
Under the common conditions, the VOCs in the ambient air are of various types and low in concentration, and need to be enriched and concentrated firstly, so that the detection requirement of an analytical instrument can be met, but due to the fact that the VOCs are of various types and complex in characteristics, particularly for gases which are difficult to trap, such as olefin, the enrichment and concentration efficiency is low, the obtained sample gas is a mixture of various gases, the gases are difficult to be completely separated only by a chromatographic separation technology, and the requirements on the test range and the precision of a chromatograph are high. At present, no device capable of synchronously enriching and preliminarily separating the sample gas by adopting a physical method for VOCs in the ambient air exists in the market. Therefore, how to perform enrichment concentration and pre-separation on volatile organic compounds is an urgent problem to be solved in the existing atmospheric pollutant detection technology.
Disclosure of Invention
The invention provides an enrichment and pre-separation system for VOCs in atmosphere, which can perform synchronous adsorption concentration and preliminary separation on VOCs in atmosphere, can perform classified collection, has high enrichment efficiency and convenient collection, and can perform self-cleaning of equipment.
The invention provides an enrichment and preseparation system for VOCs in atmosphere, which comprises a sampling device, a dewatering device, an enrichment and preseparation device and a sampling device, wherein the sampling device is used for collecting VOCs in atmosphere;
the sampling device comprises an atmospheric sampler, a first control valve and a first gas flow controller, wherein the atmospheric sampler is communicated with the first gas flow controller, and the first control valve is arranged between the atmospheric sampler and the first gas flow controller;
the water removal device comprises a first cold trap, and the first cold trap is connected with the first gas flow controller;
the enrichment and pre-separation device comprises a second cold trap, a third cold trap, a fourth cold trap, a second gas flow controller and a third gas flow controller, wherein the second cold trap comprises a second condensation pipe, and a second heating wire is wound on the surface of the second condensation pipe; the third cold trap comprises a third condensing pipe, and a third heating wire is wound on the surface of the third condensing pipe; the fourth cold trap comprises a fourth condensation pipe, and a fourth heating wire is wound on the surface of the fourth condensation pipe; the second condensing pipe is connected with the second gas flow controller, the second gas flow controller is connected with one end, far away from the first gas flow controller, of the first cold trap, and a second control valve is arranged between the second gas flow controller and the first cold trap; one end of the third condensing pipe is connected with the third gas flow controller, the other end of the third condensing pipe is connected with the fourth condensing pipe, the third gas flow controller is connected with one end of the first cold trap, which is far away from the first gas flow controller, and a third control valve is arranged between the third gas flow controller and the first cold trap;
the sampling device comprises a sampler and a carrier gas source, the sampler is connected with one end of the first cold trap, which is far away from the first gas flow controller, and a fifth control valve is arranged between the sampler and the first cold trap; the carrier gas source is connected with one end, far away from the second gas flow controller, of the second condensation pipe and one end, far away from the third condensation pipe, of the fourth condensation pipe, and a fourth control valve is arranged between the carrier gas source and the second condensation pipe and between the carrier gas source and the fourth condensation pipe.
In a preferred embodiment, the sampling device further comprises a suction pump, and the suction pump is communicated with the second condensation pipe and the fourth condensation pipe.
In a preferred embodiment, the second condensation pipe, the third condensation pipe and the fourth condensation pipe are arranged in a low-temperature environment box.
In a preferred embodiment, a first condenser pipe through hole and a second condenser pipe through hole are formed in the low-temperature environment tank, the second condenser pipe is arranged in the first condenser pipe through hole, and the third condenser pipe and the fourth condenser pipe are arranged in the second condenser pipe through hole.
In a preferred embodiment, a refrigeration piece is further arranged in the low-temperature environment box, and a cold end surface of the refrigeration piece is close to the first condenser pipe through hole and the second condenser pipe through hole; preferably, the hot end face of the refrigeration sheet is close to the radiator.
In a preferred embodiment, the number of the refrigerating sheets is at least three, and the refrigerating sheets are arranged in a stacked structure.
In a preferred embodiment, the second condensation pipe adopts refrigerant for refrigeration; preferably, the refrigerant is any one or a combination of several of liquid nitrogen, glycol and brine containing ice.
In a preferred embodiment, the fourth condensation pipe adopts refrigerant for refrigeration; preferably, the refrigerant is any one or a combination of several of liquid nitrogen, glycol and brine containing ice.
In a preferred embodiment, an olefin adsorbent is disposed within the second condenser tube.
In a preferred embodiment, a weak adsorbent is arranged in the third condensation pipe, and a strong adsorbent is arranged in the fourth condensation pipe; preferably, the weak adsorbent is a Tenax adsorbent and the strong adsorbent is an activated carbon adsorbent.
Preferably, the weak adsorbent is used for adsorbing hydrocarbons or/and oxygen-containing organic compounds containing 7 or more carbon atoms in a molecule; the strong adsorbent is used for adsorbing hydrocarbons or/and oxygen-containing organic compounds with 6 or less carbon atoms in molecules.
In a preferred embodiment, the trapping temperature of the second condensation pipe is-50 ℃ to-20 ℃, and the releasing temperature is 200 ℃ to 300 ℃.
In a preferred embodiment, the trapping temperature of the third condensing pipe is-40 ℃ to-20 ℃, and the releasing temperature is 200 ℃ to 250 ℃.
In a preferred embodiment, the trapping temperature of the fourth condensing pipe is-45 ℃ to-25 ℃, and the releasing temperature is 250 ℃ to 320 ℃.
In a preferred embodiment, the sampler is a suma tank or a gas chromatograph.
In a preferred embodiment, the first gas flow controller, the second gas flow controller, and the third gas flow controller are bi-directional gas mass flow controllers.
In a preferred embodiment, the system for enriching and pre-separating VOCs in the atmosphere works by the following method:
(1) adsorption and concentration:
the fourth control valve and the fifth control valve are closed; the first control valve, the second control valve, the third control valve and the air pump are opened, the low-temperature state of the low-temperature environment box is opened, the sample gas in the atmosphere sampler is divided into two paths after passing through the first gas flow controller and the first cold trap, one path of the sample gas passes through the second gas flow controller and reaches the second condenser pipe, and the rest gas is discharged by the air pump; the other path of the gas passes through the third gas flow controller, the third condensing pipe and the fourth condensing pipe, and the residual gas is discharged by the air pump;
(2) classifying and trapping:
first type trapping:
the low-temperature state of the low-temperature environment box is closed, the air pump, the first control valve and the third control valve are closed, the second control valve, the fourth control valve and the fifth control valve are opened, the second heating wire is started to heat the second condensation pipe, the adsorbent arranged in the second condensation pipe releases VOCs adsorbed by the adsorbent, and then the VOCs are conveyed to the sampler through the fifth control valve under the action of the back flushing gas in the carrier gas source;
second type trapping:
the low-temperature state of the low-temperature environment box is closed, the air pump, the first control valve and the second control valve are closed, the third control valve, the fourth control valve and the fifth control valve are opened, the third heating wire is started to heat the third condensation pipe, the adsorbent arranged in the third condensation pipe releases adsorbed gas, and then the fifth control valve is connected to the sampler under the action of the back flushing gas in the carrier gas source;
the third type of trapping:
and the low-temperature environment box is closed in a low-temperature state, the air pump, the first control valve and the second control valve are closed, the third control valve, the fourth control valve and the fifth control valve are opened, the fourth heating wire is started to heat the fourth condensation pipe, the adsorbent arranged in the fourth condensation pipe releases gas adsorbed by the adsorbent, and then the gas passes through the third condensation pipe and the fifth control valve to reach the sampler under the action of the back flushing gas in the carrier gas source.
In a preferred embodiment, the system for enriching and pre-separating VOCs in the atmosphere further comprises a self-cleaning device: closing the low-temperature state of the low-temperature environment box, starting the first heating wire, the second heating wire and the third heating wire, opening the first control valve, the second control valve, the third control valve and the fourth control valve, and closing the fifth control valve; the gas in the carrier gas source is divided into two paths through the fourth control valve, one path of gas passes through the second cold trap, the first cold trap and the atmosphere sampler, and the other path of gas passes through the fourth cold trap, the third cold trap and the first cold trap and the atmosphere sampler.
In a preferred embodiment, the second type of trapping is performed before the third type of trapping.
In a preferred embodiment, the gas in the carrier gas source is any one or a combination of nitrogen, helium and hydrogen.
The invention discloses an enrichment and pre-separation system for VOCs in atmosphere, which has the following beneficial effects:
(1) the first cold trap realizes the dehydration of the sample gas;
(2) the second, third and fourth cold traps are arranged to synchronously adsorb, concentrate and preliminarily separate VOCs in the sample gas, the adsorption efficiency is high, and the olefin can be trapped under the condition that the olefin adsorbent is arranged in the second condensation pipe;
(3) the VOCs subjected to preliminary adsorption and separation are respectively classified and captured through different capture passages, so that the pre-separation of various VOCs is realized;
(4) the self-cleaning of the equipment can be realized, the operation is simple, and no additional auxiliary device is needed.
Drawings
FIG. 1 is a schematic structural diagram of an atmospheric VOCs enrichment and preseparation system provided in the present invention;
fig. 2 is a schematic structural diagram of the low-temperature environment tank.
Illustration of the drawings:
11. an atmospheric sampler; 12. a first control valve; 13. a first gas flow controller; 14. a first cold trap; 15. an air pump; 2. a second cold trap; 21. a second condenser pipe; 22. a second heating wire; 23. a second gas flow controller; 24. a second control valve; 3. a third cold trap; 31. a third condenser pipe; 32. a third heating wire; 33. a third gas flow controller; 34. a third control valve; 4. a fourth cold trap; 41. a fourth condenser tube; 42. a fourth heating wire; 51. a fifth control valve; 5. a sampler; 61. a fourth control valve; 62. a carrier gas source; 7. a low temperature control box; 71. a first condenser tube through hole; 72. a second condenser tube through hole; 73. a refrigeration plate; 74. a heat sink.
Detailed Description
Example 1
The embodiment provides an enrichment and preseparation system for VOCs in atmosphere, which comprises a sampling device, a water removal device, an enrichment and preseparation device and a sampling device. As shown in fig. 1, the sampling device includes an atmospheric sampler 11, a first control valve 12, and a first gas flow controller 13, wherein the atmospheric sampler 11 is connected to the first gas flow controller 13, and the first control valve 12 is disposed between the atmospheric sampler 11 and the first gas flow controller 12. The water removal device comprises a first cold trap 14, wherein the first cold trap 14 is connected with a first gas flow controller 12.
As shown in fig. 1, the enrichment and pre-separation device comprises a second cold trap 2, a third cold trap 3, a fourth cold trap 4, a second gas flow controller 23, a third gas flow controller 33, a second control valve 24 and a third control valve 34; the second cold trap 2 comprises a second condensation pipe 21 and a second heating wire 22 arranged on the surface of the second condensation pipe 21; the third cold trap 3 includes a third condensation duct 31 and a third heating wire 32 provided on a surface of the third condensation duct 31, and the third cold trap 4 includes a fourth condensation duct 41 and a fourth heating wire 42 provided on a surface of the fourth condensation duct 41. As shown in fig. 1, one end of the first cold trap 14 away from the first gas flow controller 13, the second control valve 24, the second gas flow controller 23, and the second condenser 21 are connected in sequence; one end of the first condenser 14 far away from the first gas flow controller 13, the third control valve 34, the third gas flow controller 33, the third condensation pipe 31 and the fourth condensation pipe 41 are connected in sequence. Namely, the second cold trap 2 is connected with the third cold trap 3 and the fourth cold trap 4 in parallel.
The sampling device shown comprises a sampler 5, a fifth control valve 51 connected to the sampler 5, a carrier gas source 62, and a fourth control valve 61 connected to the carrier gas source 62. As shown in fig. 1, a fifth control valve 51 is connected to the end of the first condenser 14 remote from the first gas flow controller 13, the fifth control valve 51 controls whether the sampler 5 is in operation, and the sampler 5 can be replaced when the fifth control valve 51 is closed. The fourth control valve 61 is connected to one end of the second condensation duct 21 away from the second gas flow controller 23 and one end of the fourth condensation duct 41 away from the third condensation duct 31. Whether the blowback gas in the carrier gas source 62 can enter the second condensation duct 21, the fourth condensation duct 41 and the third condensation duct 31 can be controlled by opening and closing the fourth control valve 61.
The first cold trap 14 is provided with a desiccant, and when the gas passes through the first cold trap 14, the water vapor in the gas is adsorbed by the desiccant, so that the purpose of removing water is achieved. The first cold trap 14 can also be made of stainless steel, the inner surface of the first cold trap is passivated, a drying agent is not required to be arranged inside the first cold trap, and water vapor in the first cold trap is condensed on a stainless steel pipe, so that the aim of removing water is fulfilled.
The second condenser 21 is provided with an olefin adsorbent for adsorbing olefins in the sample gas, and the third condenser 31 is provided with a Tenax adsorbent for adsorbing hydrocarbons and oxygen-containing organic compounds containing 7 or more carbon atoms in molecules in the sample gas. The fourth condensation pipe 41 is provided with an activated carbon adsorbent for adsorbing hydrocarbons and oxygen-containing organic compounds containing 6 or less carbon atoms in molecules in the sample gas.
The trapping temperature of the second condensing pipe 21 is-40 ℃, and the releasing temperature is 300 ℃; the trapping temperature of the third condensing pipe 31 is-30 ℃, and the releasing temperature is 200 ℃; the trap temperature of the fourth condensation duct 41 is-30 deg.c and the release temperature is 300 deg.c.
The second condenser pipe 21, the third condenser pipe 31, and the fourth condenser pipe 41 are provided in the low-temperature environment tank 7. The low-temperature environment box 7 is opened when entering a low-temperature state, and the second condensation pipe 21, the third condensation pipe 31 and the fourth condensation pipe 41 are all in a low-temperature state, so that heat exchange between each condensation pipe and the outside is reduced, and the energy utilization efficiency is improved. Each condenser pipe can adopt refrigerants such as liquid nitrogen to carry out independent refrigeration, also can set up the refrigeration piece through low temperature environment case 7 and carry out the refrigeration of whole low temperature environment case 7, or the combination of both to realize when low temperature environment case 7 is in low temperature environment, the different operating temperature of its inside second condenser pipe 21, third condenser pipe 31, fourth condenser pipe 41.
The sampler 5 may be a suma tank for temporarily storing the obtained gas or a chromatograph for directly further separating and detecting the obtained gas.
In another embodiment, as shown in fig. 2, a first condenser pipe through hole 71 and a second condenser pipe through hole 72 are provided in the low-temperature environment tank 7, the second condenser pipe 21 is provided in the first condenser pipe through hole 71, and the third condenser pipe 31 and the fourth condenser pipe 41 are provided in the second condenser pipe 72. The upper side and the lower side of the first condenser pipe through hole 71 and the second condenser pipe 72 are symmetrically provided with a plurality of refrigeration sheets 73, the refrigeration sheets 73 are of a laminated structure, the cold end faces of the refrigeration sheets 73 are close to the first condenser pipe through hole 71 and the second condenser pipe through hole 73, and the hot end faces of the refrigeration sheets are close to the radiator 74. The chilling plates 73 may be semiconductor chilling plates.
Example 2
The working method of the atmospheric VOCs enriching and pre-separating system provided by the embodiment comprises the following steps: adsorption concentration, classification and trapping and self-cleaning of the equipment.
(1) Adsorption and concentration:
as shown in fig. 1, the fourth control valve 61 and the fifth control valve 51 are closed; the first control valve 12, the second control valve 24, the third control valve 34 and the air pump 15 are opened, the low-temperature state of the low-temperature environment box 7 is opened, the sample gas in the atmosphere sampler 1 enters the first cold trap 14 through the first control valve 12 and the first gas flow controller 13, and the water vapor in the sample gas is condensed on the stainless steel pipe of the first cold trap, so that the purpose of removing the water vapor is realized. The sample gas after the water vapor removal is divided into two paths, one path sequentially passes through the second control valve 24, the second gas flow controller 23 and the second condensation pipe 21, the olefin adsorbent in the second condensation pipe 21 can adsorb olefin volatile organic compounds in the sample gas, and then the residual gas is discharged by the air suction pump 15. The other sample gas passes through a third control valve 34, a third gas flow controller 33 and a third condensation pipe 31 in sequence, a Tenax adsorbent in the third condensation pipe 31 can adsorb hydrocarbons and oxygen-containing organic compounds containing 7 or more carbon atoms in the molecules of the sample gas, the rest of the sample gas is moved to a fourth condensation pipe 41 under the action of an air suction pump 15, activated carbon in the fourth condensation pipe 41 can adsorb hydrocarbons and oxygen-containing organic compounds containing 6 or less carbon atoms in the molecules of the sample gas, and the rest of the sample gas is discharged through the air suction pump 15.
This embodiment is through three condenser pipe and inside different adsorbents, with the volatile organic compounds adsorption of different categories to realized that the enrichment of volatile organic compounds is concentrated and preliminary separation, especially can carry out effectual entrapment to the olefin type gas that is difficult with the entrapment.
The classification trapping process comprises three trapping processes:
olefin capture:
closing the low-temperature state of the low-temperature environment box 7, closing the air pump 15, the first control valve 12 and the third control valve 34, opening the second control valve 24, the fourth control valve 61 and the fifth control valve 51, starting the second heating wire 22 to heat the second condensation pipe 21, releasing the olefin VOCs adsorbed in the second condensation pipe 21, back blowing the gas in the carrier gas source 62, releasing the olefin VOCs adsorbed by the olefin adsorbent in the second condensation pipe 22, and finally reaching the sampler 5 through the second gas flow controller 23, the second control valve 24 and the fifth control valve 51 under the action of the back blowing gas, thereby realizing the trapping of the olefin VOCs.
Macromolecule trapping:
closing the low-temperature state of the low-temperature environment box 7, closing the air pump 15, the first control valve 12 and the second control valve 24, opening the third control valve 34, the fourth control valve 61 and the fifth control valve 51, starting the third heating wire 32 to heat the third condensation pipe 31, adsorbing the Tenax agent in the third condensation pipe 31 to release the adsorbed macromolecular VOCs, and carrying out back flushing on the gas in the carrier gas source 62, so that the released macromolecular VOCs gas passes through the third gas flow controller 33, the third control valve 34 and reaches the sampler 5, thereby realizing the trapping of hydrocarbons and oxygen-containing organic compounds containing 7 or more carbon atoms in the molecules in the sample gas.
Small molecule trapping:
closing the low-temperature state of the low-temperature environment box 7, closing the air pump 15, the first control valve 12 and the second control valve 24, opening the third control valve 34, the fourth control valve 61 and the fifth control valve 51, starting the fourth heating wire 42 to heat the fourth condensing pipe 41, releasing the adsorbed small-molecule VOCs by the activated carbon adsorbent in the fourth condensing pipe 42, and finally reaching the sampler 5 through the third condensing pipe 31, the third gas flow controller 33 and the third control valve 34 under the back flushing action of the gas in the carrier gas source 62, so that the capture of hydrocarbons and oxygen-containing organic compounds containing 6 or less carbon atoms in the molecules is realized.
In the classified trapping process, a new sampler is replaced after each trapping process, and the olefin trapping process, the macromolecule trapping process and the micromolecule trapping process can be arranged in sequence according to actual needs. The macromolecule trapping process is carried out before the micromolecule trapping process, so that the hot gas in the fourth condensing pipe enters the third condensing pipe in the micromolecule trapping process, and the adsorbed macromolecule gas in the third condensing pipe is released to cause the mixing of the adsorbed different gas types.
Self-cleaning of the equipment:
closing the low-temperature state of the low-temperature environment box 7, starting the second heating wire 22, the third heating wire 32 and the fourth heating wire 42, opening the first control valve 12, the second control valve 24, the third control valve 34 and the fourth control valve 61, and closing the fifth control valve 51; the gas in the carrier gas source 62 is divided into two paths by the fourth control valve 61, one path is discharged after passing through the second condensation pipe 21, the first cold trap 14 and reaching the atmosphere sampler 11, and the other path is discharged after passing through the fourth condensation pipe 41, the third condensation pipe 31, the first cold trap 14 and reaching the atmosphere sampler 11. To remove impurities and some residual volatile materials in each apparatus.
The embodiments of the present invention have been described in detail, but the embodiments are merely examples, and the present invention is not limited to the embodiments described above. Any equivalent modifications and substitutions to those skilled in the art are also within the scope of the present invention. Accordingly, equivalent changes and modifications made without departing from the spirit and scope of the present invention should be covered by the present invention.

Claims (8)

1. An enrichment and preseparation system for VOCs in atmosphere is characterized by comprising a sampling device, a dewatering device, an enrichment and preseparation device and a sampling device;
the sampling device comprises an atmospheric sampler, a first control valve and a first gas flow controller, wherein the atmospheric sampler is communicated with the first gas flow controller, and the first control valve is arranged between the atmospheric sampler and the first gas flow controller;
the water removal device comprises a first cold trap, and the first cold trap is connected with the first gas flow controller;
the enrichment and pre-separation device comprises a second cold trap, a third cold trap, a fourth cold trap, a second gas flow controller and a third gas flow controller, wherein the second cold trap comprises a second condensation pipe, and a second heating wire is wound on the surface of the second condensation pipe; the third cold trap comprises a third condensing pipe, and a third heating wire is wound on the surface of the third condensing pipe; the fourth cold trap comprises a fourth condensation pipe, and a fourth heating wire is wound on the surface of the fourth condensation pipe; the second condensing pipe is connected with the second gas flow controller, the second gas flow controller is connected with one end, far away from the first gas flow controller, of the first cold trap, and a second control valve is arranged between the second gas flow controller and the first cold trap; one end of the third condensing pipe is connected with the third gas flow controller, the other end of the third condensing pipe is connected with the fourth condensing pipe, the third gas flow controller is connected with one end of the first cold trap, which is far away from the first gas flow controller, and a third control valve is arranged between the third gas flow controller and the first cold trap;
the sampling device comprises a sampler and a carrier gas source, the sampler is connected with one end of the first cold trap, which is far away from the first gas flow controller, and a fifth control valve is arranged between the sampler and the first cold trap; the carrier gas source is connected with one end, far away from the second gas flow controller, of the second condensation pipe and one end, far away from the third condensation pipe, of the fourth condensation pipe, and a fourth control valve is arranged between the carrier gas source and the second condensation pipe and between the carrier gas source and the fourth condensation pipe.
2. The system according to claim 1, wherein the second condenser tube, the third condenser tube and the fourth condenser tube are disposed in a low temperature environment tank.
3. The system according to claim 2, wherein a first condenser through hole and a second condenser through hole are formed in the low-temperature environment tank, the second condenser is arranged in the first condenser through hole, and the third condenser and the fourth condenser are arranged in the second condenser through hole.
4. The system according to claim 2, wherein the sampling device further comprises a suction pump, and the suction pump is in communication with the second condenser pipe and the fourth condenser pipe.
5. The system according to claim 4, wherein an olefin adsorbent is disposed in the second condenser tube.
6. The system according to claim 4, wherein the third condenser tube contains Tenax adsorbent, and the fourth condenser tube contains activated carbon adsorbent.
7. The system according to any one of claims 1 to 6, wherein the method comprises:
(1) adsorption and concentration:
the fourth control valve and the fifth control valve are closed; the first control valve, the second control valve, the third control valve and the air pump are opened, the low-temperature state of the low-temperature environment box is opened, the sample gas in the atmosphere sampler is divided into two paths after passing through the first gas flow controller and the first cold trap, one path of the sample gas passes through the second gas flow controller and reaches the second condenser pipe, and the rest gas is discharged by the air pump; the other path of the gas passes through the third gas flow controller, the third condensing pipe and the fourth condensing pipe, and the residual gas is discharged by the air pump;
(2) classifying and trapping:
first type trapping:
the low-temperature state of the low-temperature environment box is closed, the air pump, the first control valve and the third control valve are closed, the second control valve, the fourth control valve and the fifth control valve are opened, the second heating wire is started to heat the second condensation pipe, the adsorbent arranged in the second condensation pipe releases VOCs adsorbed by the adsorbent, and then the fifth control valve is connected to the sampler under the action of the back flushing gas in the carrier gas source;
second type trapping:
the low-temperature state of the low-temperature environment box is closed, the air pump, the first control valve and the second control valve are closed, the third control valve, the fourth control valve and the fifth control valve are opened, the third heating wire is started to heat the third condensation pipe, the adsorbent arranged in the third condensation pipe releases adsorbed gas, and then the gas passes through the fifth control valve under the action of the back flushing gas in the carrier gas source and reaches the sampler;
the third type of trapping:
and the low-temperature environment box is closed in a low-temperature state, the air pump, the first control valve and the second control valve are closed, the third control valve, the fourth control valve and the fifth control valve are opened, the fourth heating wire is started to heat the fourth condensation pipe, the adsorbent arranged in the fourth condensation pipe releases gas adsorbed by the adsorbent, and then the gas passes through the third condensation pipe, the fifth control valve and the sampler under the action of the back flushing gas in the carrier gas source.
8. The system according to claim 7, wherein the method further comprises self-cleaning of the apparatus: closing the low-temperature state of the low-temperature environment box, starting the first heating wire, the second heating wire and the third heating wire, opening the first control valve, the second control valve, the third control valve and the fourth control valve, and closing the fifth control valve; the gas in the carrier gas source is divided into two paths through the fourth control valve, one path of gas passes through the second cold trap, the first cold trap and the atmosphere sampler, and the other path of gas passes through the fourth cold trap, the third cold trap and the first cold trap and the atmosphere sampler.
CN202010488217.7A 2020-06-02 2020-06-02 Enrichment and preseparation system for VOCs in atmosphere Pending CN111521454A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP4345441A1 (en) * 2022-09-27 2024-04-03 Thermo Fisher Scientific (Shanghai) Instruments Co., Ltd. Gas detection device and method for detecting volatile organic compounds in sample gas

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP4345441A1 (en) * 2022-09-27 2024-04-03 Thermo Fisher Scientific (Shanghai) Instruments Co., Ltd. Gas detection device and method for detecting volatile organic compounds in sample gas

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