CN111551677A - System and method for monitoring VOCs in air through pre-enrichment and PID - Google Patents
System and method for monitoring VOCs in air through pre-enrichment and PID Download PDFInfo
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- 239000012855 volatile organic compound Substances 0.000 title claims abstract description 73
- 238000012544 monitoring process Methods 0.000 title claims abstract description 41
- 238000000034 method Methods 0.000 title claims abstract description 19
- 238000001514 detection method Methods 0.000 claims abstract description 37
- 238000010438 heat treatment Methods 0.000 claims abstract description 25
- 239000000126 substance Substances 0.000 claims abstract description 13
- 239000003570 air Substances 0.000 claims description 83
- 238000001179 sorption measurement Methods 0.000 claims description 32
- 239000012080 ambient air Substances 0.000 claims description 19
- 238000007781 pre-processing Methods 0.000 claims description 14
- 238000001035 drying Methods 0.000 claims description 13
- UHOVQNZJYSORNB-UHFFFAOYSA-N Benzene Chemical compound C1=CC=CC=C1 UHOVQNZJYSORNB-UHFFFAOYSA-N 0.000 claims description 9
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 7
- 230000000149 penetrating effect Effects 0.000 claims description 4
- 229920000557 Nafion® Polymers 0.000 claims description 3
- 229910052799 carbon Inorganic materials 0.000 claims description 3
- 238000004140 cleaning Methods 0.000 claims description 3
- 238000004891 communication Methods 0.000 claims description 3
- 238000003795 desorption Methods 0.000 claims description 3
- 239000002808 molecular sieve Substances 0.000 claims description 3
- URGAHOPLAPQHLN-UHFFFAOYSA-N sodium aluminosilicate Chemical compound [Na+].[Al+3].[O-][Si]([O-])=O.[O-][Si]([O-])=O URGAHOPLAPQHLN-UHFFFAOYSA-N 0.000 claims description 3
- 230000000694 effects Effects 0.000 abstract description 5
- 230000007613 environmental effect Effects 0.000 abstract description 5
- 238000010586 diagram Methods 0.000 description 4
- 238000012986 modification Methods 0.000 description 3
- 230000004048 modification Effects 0.000 description 3
- 239000003344 environmental pollutant Substances 0.000 description 2
- 231100000719 pollutant Toxicity 0.000 description 2
- 239000003463 adsorbent Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 150000002894 organic compounds Chemical class 0.000 description 1
- 238000010926 purge Methods 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
- G01N33/0004—Gaseous mixtures, e.g. polluted air
- G01N33/0009—General constructional details of gas analysers, e.g. portable test equipment
- G01N33/0011—Sample conditioning
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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
- G01N1/28—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
- G01N1/44—Sample treatment involving radiation, e.g. heat
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
- G01N33/0004—Gaseous mixtures, e.g. polluted air
- G01N33/0006—Calibrating gas analysers
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
- G01N33/0004—Gaseous mixtures, e.g. polluted air
- G01N33/0009—General constructional details of gas analysers, e.g. portable test equipment
- G01N33/0011—Sample conditioning
- G01N33/0019—Sample conditioning by preconcentration
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
- G01N33/0004—Gaseous mixtures, e.g. polluted air
- G01N33/0009—General constructional details of gas analysers, e.g. portable test equipment
- G01N33/0027—General constructional details of gas analysers, e.g. portable test equipment concerning the detector
- G01N33/0036—General constructional details of gas analysers, e.g. portable test equipment concerning the detector specially adapted to detect a particular component
- G01N33/0047—Organic compounds
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Abstract
The invention provides a system for monitoring VOCs in air by pre-enrichment and PID, which comprises a pre-enrichment system and a PID monitoring system, wherein a pretreatment unit and a pre-enrichment unit are arranged in the pre-enrichment system, a PID detection unit is arranged in the PID monitoring system, factory environment air is introduced into the pre-enrichment unit to collect trace substances to be measured, the concentration is improved, the trace substances are released in a concentrated manner by heating, the factory environment air is adsorbed and dehumidified by the pretreatment unit and then introduced into the pre-enrichment unit, and gas in the pre-enrichment unit is blown to the PID detection unit for detection and analysis, so that the system and the method for monitoring the VOCs in the air by pre-enrichment and PID have the effect of improving the response of a sensor to the VOCs substances under the condition that the environmental concentration of the VOCs is not changed.
Description
Technical Field
The invention relates to the technical field of environmental atmosphere monitoring, in particular to a system and a method for monitoring VOCs in air through pre-enrichment and PID.
Background
Volatile Organic Compounds (VOCs) are an important class of gaseous pollutants, and generally refer to organic compounds having a boiling point of 50 to 260 ℃ at normal pressure and a saturated vapor pressure of more than 133.32Pa at room temperature. VOCs, as important gaseous pollutants, have significant effects on both the atmospheric environment and human health.
However, in the factory environment air with unorganized emission, the content of VOCs is often very low, and most sensors have very small response to low-concentration VOCs, so that the sensors cannot be applied to actual life.
Disclosure of Invention
The embodiment of the invention provides a system and a method for monitoring VOCs in air by pre-enrichment and PID, which make up the defects of a sensor by adding a pre-enrichment unit, namely before gas enters a sensor testing cavity, the gas is concentrated and enriched, and then conditions are changed to quickly desorb the VOCs, so that the concentration of a detected object can be improved, and under the condition that the environmental concentration of the VOCs is not changed, the response of the sensor to VOCs substances is improved, so that the problem that the response of the existing sensor to low-concentration VOCs is small is solved.
In view of the above problems, the technical solution proposed by the present invention is:
a system for pre-enrichment + PID monitoring of VOCs in air, comprising: the device comprises a pre-enrichment system, a PID monitoring system, an air pump and a controller.
The pre-enrichment system comprises a first pipeline, a pretreatment unit, a first electromagnetic valve, a first three-way pipe, a pre-enrichment unit, a third three-way pipe, a fifth electromagnetic valve and a fifth three-way pipe;
the first pipeline is sequentially connected with the first pipeline, the pretreatment unit, the first electromagnetic valve, the first three-way pipe, the pre-enrichment unit, the third three-way pipe, the fifth electromagnetic valve and the fifth three-way pipe in a penetrating manner from left to right and is communicated with an air pump, an adsorption element and a drying element are respectively arranged in the pretreatment unit, the adsorption element is arranged on one side of the drying element, the pre-enrichment unit comprises a heating component and an adsorption component, and the heating component is arranged on one side of the adsorption component;
the PID monitoring system comprises a second electromagnetic valve, a second three-way pipe, a third electromagnetic valve, a fourth three-way pipe, a fourth electromagnetic valve, a PID detection unit, a second pipeline, a third pipeline and a fourth pipeline;
the second pipeline is sequentially connected with the second electromagnetic valve, the second three-way pipe, the third electromagnetic valve, the fourth three-way pipe, the fourth electromagnetic valve and the PID detection unit in a penetrating manner from left to right and is communicated with one end of the fifth three-way pipe, one end of the third pipeline is communicated with one end of the first three-way pipe, the other end of the third pipeline is communicated with one end of the second three-way pipe, one end of the fourth pipeline is communicated with one end of the third three-way pipe, and the other end of the fourth pipeline is communicated with one end of the fourth three-way pipe;
the controller is respectively in communication connection with the first electromagnetic valve, the second electromagnetic valve, the third electromagnetic valve, the fourth electromagnetic valve, the fifth electromagnetic valve, the PID detection unit, the air pump and the heating component.
In order to better realize the technical scheme of the invention, the following technical measures are also adopted.
Further, the pre-enrichment unit is any one of an adsorption tube or an MEMS micro-concentrator.
Furthermore, the adsorption element is a pipe fitting loaded with an activated carbon adsorption substance and used for adsorbing VOCs in the air, the drying element is any one of a nafion pipe fitting or a pipe fitting loaded with a molecular sieve, and the drying element is used for absorbing moisture in the air.
Furthermore, the adsorption component is used for adsorbing VOCs in the air, and the heating component is used for heating the adsorption component to release the VOCs adsorbed in the adsorption component.
An operation method of a system for monitoring VOCs in air by pre-enrichment and PID comprises the following steps:
s1, in an adsorption mode, operating the controller to start the air pump, starting the second electromagnetic valve and the fifth electromagnetic valve, closing the first electromagnetic valve, the third electromagnetic valve and the fourth electromagnetic valve, allowing ambient air from a factory to enter from the second pipeline under the suction of the air pump, allowing the ambient air to enter the pre-enrichment unit through the second electromagnetic valve and the first three-way pipe in sequence, and enriching VOCs (volatile organic compounds) to be analyzed in the pre-enrichment unit;
s2, in a desorption mode, the operation controller closes the air pump and closes the first electromagnetic valve, the second electromagnetic valve, the third electromagnetic valve, the fourth electromagnetic valve and the fifth electromagnetic valve, and the heating component of the pre-enrichment unit is started to fully desorb the adsorbed VOCs;
s3, in an analysis mode, operating the controller to start the air pump, opening the first electromagnetic valve, the fourth electromagnetic valve, closing the second electromagnetic valve, the third electromagnetic valve and the fifth electromagnetic valve, allowing ambient air from a factory to enter from the first pipeline under the suction of the air pump, allowing the ambient air to sequentially enter the PID detection unit through the pretreatment unit, the first electromagnetic valve, the pre-enrichment unit, the third three-way pipe, the fourth three-way pipe and the fourth electromagnetic valve, and introducing the desorbed VOCs in the pre-enrichment unit into the PID detection unit for analysis;
s4, in a cleaning mode, the operation controller starts the air pump, the first electromagnetic valve, the fifth electromagnetic valve are opened, the second electromagnetic valve, the third electromagnetic valve and the fourth electromagnetic valve are closed, under the suction of the air pump, factory environment air enters from the first pipeline and sequentially passes through the pretreatment unit, the first electromagnetic valve, the first three-way pipe, the pre-enrichment unit, the third three-way pipe, the fifth electromagnetic valve and the fifth three-way pipe, and the pre-enrichment unit is purged by air;
and S5, looping and repeating the steps S1-S4.
A maintenance and calibration method for a pre-enrichment + PID monitoring system for VOCs in air comprises the following steps:
in the Sa baseline mode, the controller is operated to start the air pump, the first electromagnetic valve, the third electromagnetic valve and the fifth electromagnetic valve are opened, the second electromagnetic valve and the fourth electromagnetic valve are closed, the ambient air in the factory is introduced from the first pipeline and sequentially passes through the preprocessing unit, the first electromagnetic valve, the first three-way pipe, the pre-enrichment unit, the third three-way pipe, the fifth electromagnetic valve and the fifth three-way pipe, the VOCs (volatile organic compounds) components and moisture in the ambient air are removed through the preprocessing unit, and the controller acquires a detection electric signal of the PID detection unit in the hydrocarbon-removed air for data comparison in future monitoring;
and Sb, in the calibration mode, introducing benzene calibration gas with known concentration through a second pipeline, repeating the steps S1-S4, converting the concentration of the calibration gas into carbon, and writing the analyzed data into a PID detection unit to realize the calibration of the VOCs.
Compared with the prior art, the invention has the beneficial effects that: the system and the method for monitoring the VOCs in the air through the pre-enrichment unit have the advantages that the pre-enrichment system and the PID monitoring system are arranged, the pre-processing unit and the pre-enrichment unit are arranged in the pre-enrichment system, the PID detection unit is arranged in the PID monitoring system, the factory boundary ambient air is introduced into the pre-enrichment unit to collect trace substances to be measured, the concentration is improved, the trace substances are released in a heating mode, the factory boundary ambient air is adsorbed and dehumidified through the pre-processing unit, then the pre-enrichment unit is introduced to blow gas in the pre-enrichment unit to the PID detection unit to carry out detection and analysis, and therefore the system and the method for monitoring the VOCs in the air through the pre-enrichment and the PID have the effect of improving the response of a sensor to the VOCs under the.
The foregoing description is only an overview of the technical solutions of the present invention, and the embodiments of the present invention are described below in order to make the technical means of the present invention more clearly understood and to make the above and other objects, features, and advantages of the present invention more clearly understandable.
Drawings
FIG. 1 is a schematic structural diagram of a system for monitoring VOCs in air by pre-enrichment and PID according to an embodiment of the present invention;
FIG. 2 is a schematic structural diagram of a pre-processing unit according to an embodiment of the present invention;
FIG. 3 is a schematic structural diagram of a pre-enrichment unit disclosed in an embodiment of the present invention;
FIG. 4 is a schematic flow chart of a method for operating a pre-enrichment + PID system for monitoring VOCs in air according to an embodiment of the present invention;
FIG. 5 is a schematic flow chart illustrating a method for maintaining and calibrating a pre-enrichment + PID system for monitoring VOCs in air according to an embodiment of the present invention;
fig. 6 is a communication flow diagram of a system for monitoring VOCs in air by pre-enrichment and PID, which is disclosed in the embodiment of the present invention.
Reference numerals:
1-a pre-enrichment system; 101-a first conduit; 102-a pre-processing unit; 10201-an adsorption element; 10202-drying element; 103-a first solenoid valve; 104-a first tee; 105-a pre-enrichment unit; 10501-a heating means; 10502-an adsorbent member; 106-third tee; 107-fifth solenoid valve; 108-a fifth tee; 2-a PID monitoring system; 201-a second solenoid valve; 202-a second tee; 203-third electromagnetic valve; 204-a fourth tee; 205-a fourth solenoid valve; 206-PID detection unit; 207-a second conduit; 208-a third conduit; 209-a fourth conduit; 3, an air pump; 4-a controller.
DETAILED DESCRIPTION OF EMBODIMENT (S) OF INVENTION
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments.
Referring to fig. 1-6, a system for pre-enriching + PID monitoring VOCs in air includes a pre-enriching system 1, the pre-enriching system 1 includes a first pipe 101, a pre-processing unit 102, a first electromagnetic valve 103, a first three-way pipe 104, a pre-enriching unit 105, a third three-way pipe 106, a fifth electromagnetic valve 107 and a fifth three-way pipe 108, the first pipe 101 is sequentially connected from left to right through the first pipe 101, the pre-processing unit 102, the first electromagnetic valve 103, the first three-way pipe 104, the pre-enriching unit 105, the third three-way pipe 106, the fifth electromagnetic valve 107 and the fifth three-way pipe 108 and is communicated with an air pump 3, an adsorption element 10201 and a drying element 10202 are respectively disposed in the pre-processing unit 102, the adsorption element 10201 is disposed on one side of the drying element 10202 for adsorbing VOCs in air, the drying element 10202 is any one of a nafion pipe or a pipe carrying molecular sieve, the drying element 10202 for absorbing moisture in air, the pre-enrichment unit 105 comprises a heating component 10501 and an adsorption component 10502, the heating component 10501 is arranged on one side of the adsorption component 10502, the pre-enrichment unit 105 is any one of an adsorption pipe or an MEMS micro-concentrator, the adsorption component 10502 is used for adsorbing VOCs in air, the heating component 10501 is used for heating the adsorption component 10502 to release the VOCs adsorbed in the adsorption component 10502, the PID monitoring system 2 comprises a second electromagnetic valve 201, a second three-way pipe 202, a third electromagnetic valve 203, a fourth three-way pipe 204, a fourth electromagnetic valve 205, a PID detection unit 206, a second pipeline 207, a third pipeline 208 and a fourth pipeline 209, the second pipeline 207 is sequentially connected with the second electromagnetic valve 201, the second three-way pipe 202, the third electromagnetic valve 203, the fourth three-way pipe 204, the fourth electromagnetic valve 205 and the PID detection unit 206 from left to right and is communicated with one end of a fifth three-way pipe 108, one end of the third pipeline 208 is communicated with one end of the first three-way pipe 104, the other end of the third pipeline 208 is communicated with one end of the second three-way pipe 202, one end of the fourth pipeline 209 is communicated with one end of the third three-way pipe 106, the other end of the fourth pipeline 209 is communicated with one end of the fourth three-way pipe 204, the controller 4 is respectively communicated with the first electromagnetic valve 103, the second electromagnetic valve 201, the third electromagnetic valve 203, the fourth electromagnetic valve 205, the fifth electromagnetic valve 107, the PID detection unit 206, the air pump 3 and the heating component 10501, the pre-enrichment system 1 is provided with the pre-processing unit 102 and the pre-enrichment unit 105, the PID detection unit 206 is provided in the PID monitoring system 2, the plant ambient air is introduced into the pre-enrichment unit 105 to collect trace substances to be measured in a centralized manner, the concentration is increased, the trace substances are released in a centralized manner by heating, and the gas in the pre-enrichment unit 105 is purged by the pre-processing unit 105 after the plant ambient air is adsorbed and dehumidified by the pre-processing unit 102 The PID detection unit 206 performs detection and analysis, so that the system and the method for monitoring VOCs in air by pre-enrichment and PID have the effect of improving the response of the sensor to VOCs substances under the condition that the environmental concentration of VOCs is not changed.
The embodiment of the invention is also realized by the following technical scheme.
Referring to fig. 1-4, a method of operating a system for pre-enrichment + PID monitoring of VOCs in air, comprising the steps of:
s1, in an adsorption mode, the air pump 3 is started by the operation controller 4, the second electromagnetic valve 201 and the fifth electromagnetic valve 107 are opened, the first electromagnetic valve 103, the third electromagnetic valve 203 and the fourth electromagnetic valve 205 are closed, under the suction of the air pump 3, the factory environment air enters from the second pipeline 207, sequentially passes through the second electromagnetic valve 201 and the first three-way pipe 104 and enters the pre-enrichment unit 105, and VOCs to be analyzed are enriched in the pre-enrichment unit 105;
s2, in the desorption mode, the operation controller 4 closes the air pump 3 and the first solenoid valve 103, the second solenoid valve 201, the third solenoid valve 203, the fourth solenoid valve 205, and the fifth solenoid valve 107, and the pre-enrichment unit 105 starts the heating element 10501 to fully desorb the adsorbed VOCs;
s3, in an analysis mode, the controller 4 is operated to start the air pump 3, the first electromagnetic valve 103 and the fourth electromagnetic valve 205 are opened, the second electromagnetic valve 201, the third electromagnetic valve 203 and the fifth electromagnetic valve 107 are closed, ambient air from the factory environment enters from the first pipeline 101 under the suction of the air pump 3, and sequentially enters the PID detection unit 206 through the pretreatment unit 102, the first electromagnetic valve 103, the pre-enrichment unit 105, the third three-way pipe 106, the fourth three-way pipe 204 and the fourth electromagnetic valve 205, and the desorbed VOCs in the pre-enrichment unit 105 are introduced into the PID detection unit 206 for analysis, so as to obtain analysis data;
s4, in a cleaning mode, the operation controller 4 starts the air pump 3, the first electromagnetic valve 103 and the fifth electromagnetic valve 107 are opened, the second electromagnetic valve 201, the third electromagnetic valve 203 and the fourth electromagnetic valve 205 are closed, and under the suction of the air pump 3, the factory environment air enters from the first pipeline 101, sequentially passes through the pretreatment unit 102, the first electromagnetic valve 103, the first three-way pipe 104, the pre-enrichment unit 105, the third three-way pipe 106, the fifth electromagnetic valve 107 and the fifth three-way pipe 108, and purges the pre-enrichment unit 105, so that the next monitoring period can be conveniently started;
and S5, looping and repeating the steps S1-S4.
Referring to fig. 1-5, a method for maintaining and calibrating a system for monitoring VOCs in air by pre-enrichment + PID, comprising the steps of:
in Sa, in the baseline mode, the controller 4 is operated to start the air pump 3, the first electromagnetic valve 103, the third electromagnetic valve 203 and the fifth electromagnetic valve 107 are opened, the second electromagnetic valve 201 and the fourth electromagnetic valve 205 are closed, the ambient air in the factory environment enters from the first pipeline 101, sequentially passes through the pretreatment unit 102, the first electromagnetic valve 103, the first three-way pipe 104, the pre-enrichment unit 105, the third three-way pipe 106, the fifth electromagnetic valve 107 and the fifth three-way pipe 108, and is subjected to removal of VOCs and moisture in the air by the pretreatment unit 102, and the controller 4 obtains a detection electric signal of the PID detection unit 206 in the hydrocarbon-removed air for data comparison in future monitoring;
sb, calibration mode, in which a benzene calibration gas with a known concentration is introduced through the second pipe 207, steps S1 to S4 are repeated, the concentration of the calibration gas is converted into carbon, and the analyzed data is written into the PID detection unit 206, thereby realizing calibration of VOCs.
Specifically, the operation controller 4 starts the air pump 3, the second electromagnetic valve 201 and the fifth electromagnetic valve 107 are opened, the first electromagnetic valve 103, the third electromagnetic valve 203 and the fourth electromagnetic valve 205 are closed, under the suction of the air pump 3, the factory environment air enters from the second pipeline 207, sequentially enters the pre-enrichment unit 105 through the second electromagnetic valve 201 and the first three-way pipe 104, the VOCs to be analyzed are enriched in the pre-enrichment unit 105, the operation controller 4 closes the air pump 3, the first electromagnetic valve 103, the second electromagnetic valve 201, the third electromagnetic valve 203, the fourth electromagnetic valve 205 and the fifth electromagnetic valve 107, the heating part 10501 of the pre-enrichment unit 105 is started, so that the adsorbed VOCs are fully desorbed, the operation controller 4 starts the air pump 3, the first electromagnetic valve 103 and the fourth electromagnetic valve 205 are opened, the second electromagnetic valve 201, the third electromagnetic valve 203 and the fifth electromagnetic valve 107 are closed, under the suction of the air pump 3, ambient air of a factory boundary enters from the first pipeline 101, sequentially passes through the pretreatment unit 102, the first electromagnetic valve 103, the pre-enrichment unit 105, the third three-way pipe 106, the fourth three-way pipe 204 and the fourth electromagnetic valve 205, enters the PID detection unit 206, and the VOCs substances desorbed in the pre-enrichment unit 105 are introduced into the PID detection unit 206 to be analyzed to obtain analysis data, so that the system and the method for monitoring VOCs in air by pre-enrichment and PID have the effect of improving the response of a sensor to the VOCs substances under the condition that the environmental concentration of the VOCs is not changed.
It should be noted that the specific model specifications of the controller 4, the first electromagnetic valve 103, the second electromagnetic valve 201, the third electromagnetic valve 203, the fourth electromagnetic valve 205, the fifth electromagnetic valve 107, the PID detection unit 206, the air pump 3, and the heating component 10501 need to be determined according to the actual specification of the device, and the specific model selection calculation method adopts the prior art in the field, and therefore, detailed description is omitted.
The power supply of the controller 4, the first solenoid valve 103, the second solenoid valve 201, the third solenoid valve 203, the fourth solenoid valve 205, the fifth solenoid valve 107, the PID detecting unit 206, the air pump 3, and the heating part 10501, and the principle thereof will be apparent to those skilled in the art, and will not be described in detail herein.
It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.
Claims (6)
1. A system for pre-enrichment + PID monitoring of VOCs in air, comprising:
the pre-enrichment system comprises a first pipeline, a pretreatment unit, a first electromagnetic valve, a first three-way pipe, a pre-enrichment unit, a third three-way pipe, a fifth electromagnetic valve and a fifth three-way pipe;
the first pipeline is sequentially connected with the first pipeline, the pretreatment unit, the first electromagnetic valve, the first three-way pipe, the pre-enrichment unit, the third three-way pipe, the fifth electromagnetic valve and the fifth three-way pipe in a penetrating manner from left to right and is communicated with an air pump, an adsorption element and a drying element are respectively arranged in the pretreatment unit, the adsorption element is arranged on one side of the drying element, the pre-enrichment unit comprises a heating component and an adsorption component, and the heating component is arranged on one side of the adsorption component;
the PID monitoring system comprises a second electromagnetic valve, a second three-way pipe, a third electromagnetic valve, a fourth three-way pipe, a fourth electromagnetic valve, a PID detection unit, a second pipeline, a third pipeline and a fourth pipeline;
the second pipeline is sequentially connected with the second electromagnetic valve, the second three-way pipe, the third electromagnetic valve, the fourth three-way pipe, the fourth electromagnetic valve and the PID detection unit in a penetrating manner from left to right and is communicated with one end of the fifth three-way pipe, one end of the third pipeline is communicated with one end of the first three-way pipe, the other end of the third pipeline is communicated with one end of the second three-way pipe, one end of the fourth pipeline is communicated with one end of the third three-way pipe, and the other end of the fourth pipeline is communicated with one end of the fourth three-way pipe;
and the controller is respectively in communication connection with the first electromagnetic valve, the second electromagnetic valve, the third electromagnetic valve, the fourth electromagnetic valve, the fifth electromagnetic valve, the PID detection unit, the air pump and the heating part.
2. The system for pre-enriching + PID monitoring of VOCs in air according to claim 1, wherein: the pre-enrichment unit is any one of an adsorption tube or an MEMS micro-concentrator.
3. The system for pre-enriching + PID monitoring of VOCs in air according to claim 1, wherein: the adsorption element is a pipe fitting loaded with an activated carbon adsorption substance and used for adsorbing VOCs in air, the drying element is any one of a nafion pipe fitting or a pipe fitting loaded with a molecular sieve, and the drying element is used for absorbing moisture in air.
4. The system for pre-enriching + PID monitoring of VOCs in air according to claim 1, wherein: the adsorption component is used for adsorbing VOCs in the air, and the heating component is used for heating the adsorption component to release the VOCs adsorbed in the adsorption component.
5. A method of operating a system for monitoring VOCs in air using the pre-enrichment + PID as claimed in claims 1-4, wherein: the method comprises the following steps:
s1, in an adsorption mode, operating the controller to start the air pump, starting the second electromagnetic valve and the fifth electromagnetic valve, closing the first electromagnetic valve, the third electromagnetic valve and the fourth electromagnetic valve, allowing ambient air from a factory to enter from the second pipeline under the suction of the air pump, allowing the ambient air to enter the pre-enrichment unit through the second electromagnetic valve and the first three-way pipe in sequence, and enriching VOCs (volatile organic compounds) to be analyzed in the pre-enrichment unit;
s2, in a desorption mode, the controller is operated to close the air pump and the first electromagnetic valve, the second electromagnetic valve, the third electromagnetic valve, the fourth electromagnetic valve and the fifth electromagnetic valve, and the heating component of the pre-enrichment unit is started to fully desorb the adsorbed VOCs;
s3, in an analysis mode, operating the controller to start the air pump, opening the first electromagnetic valve, the fourth electromagnetic valve, closing the second electromagnetic valve, the third electromagnetic valve and the fifth electromagnetic valve, allowing ambient air from a factory to enter from the first pipeline under the suction of the air pump, allowing the ambient air to sequentially enter the PID detection unit through the pretreatment unit, the first electromagnetic valve, the pre-enrichment unit, the third three-way pipe, the fourth three-way pipe and the fourth electromagnetic valve, and introducing the desorbed VOCs in the pre-enrichment unit into the PID detection unit for analysis;
s4, in a cleaning mode, the operation controller starts the air pump, the first electromagnetic valve, the fifth electromagnetic valve are opened, the second electromagnetic valve, the third electromagnetic valve and the fourth electromagnetic valve are closed, under the suction of the air pump, factory environment air enters from the first pipeline and sequentially passes through the pretreatment unit, the first electromagnetic valve, the first three-way pipe, the pre-enrichment unit, the third three-way pipe, the fifth electromagnetic valve and the fifth three-way pipe, and the pre-enrichment unit is purged by air;
and S5, looping and repeating the steps S1-S4.
6. A method of maintaining and calibrating a system for monitoring VOCs in air using the pre-enrichment + pid of claims 1-5, wherein: the method comprises the following steps:
in the Sa baseline mode, the controller is operated to start the air pump, the first electromagnetic valve, the third electromagnetic valve and the fifth electromagnetic valve are opened, the second electromagnetic valve and the fourth electromagnetic valve are closed, the ambient air in the factory is introduced from the first pipeline and sequentially passes through the preprocessing unit, the first electromagnetic valve, the first three-way pipe, the pre-enrichment unit, the third three-way pipe, the fifth electromagnetic valve and the fifth three-way pipe, the VOCs (volatile organic compounds) components and moisture in the ambient air are removed through the preprocessing unit, and the controller acquires a detection electric signal of the PID detection unit in the hydrocarbon-removed air for data comparison in future monitoring;
and Sb, in the calibration mode, introducing benzene calibration gas with known concentration through a second pipeline, repeating the steps S1-S4, converting the concentration of the calibration gas into carbon, and writing the analyzed data into a PID detection unit to realize the calibration of the VOCs.
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