CN112345657B - Array sensing gas chromatograph and method for detecting multiple VOCs gases - Google Patents

Array sensing gas chromatograph and method for detecting multiple VOCs gases Download PDF

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CN112345657B
CN112345657B CN201910729991.XA CN201910729991A CN112345657B CN 112345657 B CN112345657 B CN 112345657B CN 201910729991 A CN201910729991 A CN 201910729991A CN 112345657 B CN112345657 B CN 112345657B
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gas
way valve
port
valve
concentration
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CN112345657A (en
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翁小平
王哲刚
诸益霖
陈涛
李尤
汪桢
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Shanghai Ensmax Environmental Protection Technology Co ltd
Baowu Carbon Technology Co ltd
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Shanghai Ensmax Environmental Protection Technology Co ltd
Baowu Carbon Technology Co ltd
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
    • G01N30/02—Column chromatography
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
    • G01N30/02—Column chromatography
    • G01N30/04—Preparation or injection of sample to be analysed
    • G01N30/06—Preparation
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
    • G01N30/02—Column chromatography
    • G01N30/04—Preparation or injection of sample to be analysed
    • G01N30/06—Preparation
    • G01N30/14—Preparation by elimination of some components
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
    • G01N30/02—Column chromatography
    • G01N2030/022—Column chromatography characterised by the kind of separation mechanism
    • G01N2030/025—Gas chromatography
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
    • G01N30/02—Column chromatography
    • G01N30/04—Preparation or injection of sample to be analysed
    • G01N30/06—Preparation
    • G01N2030/062—Preparation extracting sample from raw material
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
    • Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters

Abstract

The invention provides an array sensing gas chromatography detector capable of realizing gas detection of various VOCs (volatile organic compounds) and a detection method, comprising the steps of mixing gas to be detected and N 2 The first pipeline is connected with the first end of the six-way valve, and a gas sampling filter is arranged on the first pipeline; the second end of the six-way valve is connected with the air inlet of the gas preconcentration device, and the air outlet of the six-way valve is connected with the fifth end of the six-way valve; the second pipeline is connected with the first end of the first three-way valve, and the third end of the first three-way valve is connected with the third end of the six-way valve; the second end of the first three-way valve is connected with the second end of the second three-way valve through a switch valve; the third end of the second three-way valve is connected with the fourth end of the six-way valve through a switching valve; the first end of the second three-way valve is connected with a gas chromatographic column, and the gas chromatographic column is connected with an array sensing detector; the sixth end of the six-way valve is connected with a negative pressure pump; the detector is in a sample pre-concentration mode, a first two end of the six-way valve is connected, a third four end is connected, and a fifth six end is connected; and under the analysis mode of the detector, the first six end of the six-way valve is communicated, the second three end is communicated, and the fourth five end is communicated.

Description

Array sensing gas chromatograph and method for detecting multiple VOCs gases
Technical Field
The invention belongs to the technical field of gas detection, and particularly relates to an array sensing gas chromatography detector and a detection method capable of realizing gas detection of multiple VOCs.
Background
At present, for component detection of VOCs gas in air environment or at a chimney exhaust port, a traditional detection method for separating single gas by using a chromatographic analysis method is generally adopted. However, because the components in the environment are complex and various, and there are not only permanent gases but also volatile organic gases, etc., the above methods have great limitations in order to detect the components of the environmental gases.
For gas chromatographic analysis, a gas chromatographic column is divided into nonpolar, weak polar, medium polar, strong polar and the like, and a special chromatographic column can only be used for separating special substances, but cannot separate all gases. Different organic gases cannot be separated by using the same chromatographic column at the same time, for example, a nonpolar chromatographic column can be used for separating hydrocarbons and phenols, but cannot be used for separating alcohols. Therefore, the analysis of all components inevitably leads to the complex peripheral gas circuit system of the chromatographic detector, the complex operation and the long analysis time, and the wide application of the on-line monitoring is limited.
Disclosure of Invention
The technical problem to be solved by the invention is to overcome the defects in the prior art and provide an array sensing chromatographic detector capable of realizing gas detection of various VOCs.
The technical problem to be solved can be implemented by the following technical scheme.
The utility model provides a can realize gaseous array sensing gas chromatography detector that detects of multiple VOCs which characterized in that includes:
the gas inlet pipeline is connected with a first port of the six-way valve, and a gas sampling filter is arranged on the first gas inlet pipeline; the second port of the six-way valve is connected with the gas inlet of a gas preconcentration device, and the gas outlet of the gas preconcentration device is connected with the fifth port of the six-way valve; and
a will purge N 2 A second air inlet pipeline of the detector is introduced, the second air inlet pipeline is connected with a first port of a first three-way valve, and a third port of the first three-way valve is connected with a third port of the six-way valve; the second port of the first three-way valve is connected with the second port of a second three-way valve through a first switch valve; a third port of the second three-way valve is connected with a fourth port of the six-way valve through a second switch valve; the first port of the second three-way valve is connected with a gas chromatographic column, and the gas chromatography is carried outThe column is connected with an array sensing detector; and
the negative pressure pump is connected with the sixth port of the six-way valve;
wherein the content of the first and second substances,
the detector is in a sample pre-concentration mode, a first port of the six-way valve is communicated with a second port, a third port of the six-way valve is communicated with a fourth port of the six-way valve, and a fifth port of the six-way valve is communicated with a sixth port of the six-way valve;
when the detector is in an analysis mode, the first port of the six-way valve is communicated with the sixth port, the second port of the six-way valve is communicated with the third port of the six-way valve, and the fourth port of the six-way valve is communicated with the fifth port of the six-way valve; the first switch valve is opened, the second switch valve is closed, and the negative pressure pump is closed.
As a further improvement of the technical scheme, the gas pre-concentration device is a three-stage pre-concentration column with a cooling system and a heating system, and the packed adsorbate of each stage of the three-stage pre-concentration column is different.
As a further improvement of the present technical solution, a first flow rate adjusting valve is provided between the second port of the first three-way valve and the second port of the second three-way valve; a second flow regulating valve is arranged between the third port of the first three-way valve and the third port of the second three-way valve; n flowing from the first three-way valve to the second three-way valve to the gas chromatography column through the first flow regulating valve 2 Relative to N flowing to the gas chromatography column through the second flow regulating valve 2 And the flow ratio is 0.
As a further improvement of the technical scheme, the adsorption material filled in the third-stage pre-concentration column concentrator is one or a combination of a plurality of molecular sieves, tenax-TA and activated carbon Carbopack.
As one of the preferred embodiments of the present invention, the desorption temperature of the three-stage preconcentration column is 60 to 300 ℃.
Also as one of the preferred embodiments of the present invention, the array sensing detector is an array sensing detector composed of a semiconductor material VOCs gas sensor processed by MEMS, a chemical sensor, a micro ultraviolet light ion VOCs gas sensor and a micro infrared laser VOCs gas sensor; the array sensor is connected with a sensing signal acquisition card which can convert physical signals into electric signals.
Furthermore, a single group of the array sensing detector consists of six sensors, and the sensing acquisition frequency of the single sensor is more than or equal to 10 times/second.
As a further aspect of the present disclosure, a first pressure maintaining valve and a second pressure maintaining valve are disposed on the first air intake pipeline; and a primary pressure stabilizing valve and a secondary pressure stabilizing valve are arranged on the second air inlet pipeline.
As one of the preferred embodiments of the present invention, the gas chromatography column is a micro MEMS gas chromatography column or a capillary gas chromatography column.
Similarly, an air filter membrane for filtering dust and water vapor in the air is arranged in the gas sampling filter.
Also as a preferred embodiment of the present invention, the negative pressure pump is a sampling diaphragm pump.
Another technical problem to be solved by the present invention is to provide a detection method capable of detecting multiple VOCs, which is characterized in that the array sensing gas chromatography detector is adopted, and the method comprises the following steps:
(1) The gas to be detected sequentially enters a gas sample introduction filter, a primary pressure stabilizing device and a secondary pressure stabilizing device through the pumping force of a negative pressure pump, and then enters a pre-concentration device to concentrate the VOCs components to be detected in the sample gas; controlling sampling time through a prefabricated program, wherein the sampling time is in direct proportion to the concentration multiple and the detection precision;
(2) After the pre-concentration of the analysis sample gas is finished, entering an analysis mode through the switching of a six-way valve; in an analysis mode, a negative pressure pump serving as a sampling pump stops sampling, a temperature control system of the pre-concentration device is rapidly heated to a specified desorption temperature, the temperature interval is 60-300 ℃, and the second switch valve is in a closed state during the period;
(3) After reaching a prescribed temperature, N 2 The component of the gas to be measured is purged and desorbed from the pre-concentration device as the purging carrier gas, and the purging desorption process is continuousThe time can be adjusted; n is a radical of hydrogen 2 The carrier gas carries gas to enter the gas chromatographic column for component separation; the working temperature of the gas chromatographic column is 50-180 ℃;
(4) And finally, the gas to be detected enters the array sensing detector with controllable temperature, and is analyzed in a form of a chromatographic chart after being collected according to the set collection frequency.
Further, step (4) of the method includes the step of determining the concentration and composition of gaseous VOCs species by comparison to a library of spectra.
Still further, the method may further comprise setting and adjusting bypass N 2 And a gas path, and mixing the gas path with a sample gas path to be analyzed and then feeding the mixture into the gas chromatographic column.
The array sensing gas chromatography detector and the detection method adopting the technical scheme have the following beneficial effects:
1. analysis of all gas components of the ambient gas can be achieved by the combination of the chromatographic columns with the array VOCs sensing units, without the need for multiple chromatographic columns.
2. The detection time is shortened, and the requirements on chromatographic columns are lower.
3. By adopting MEMS array sensing and micro-chromatography, the instrument has simpler design structure and low cost, can realize portable/handheld type and is easy to be widely used in multiple fields.
4. The integrated pre-concentration column can realize the detection of trace environmental gas, the detection limit can reach 0.01ppb, and the application range of the detector is improved.
Drawings
FIG. 1 is a schematic diagram of a multi-sensor chromatographic detector in a pre-concentration mode;
FIG. 2 is a schematic diagram of a multisensor chromatography detector in an analysis mode according to an embodiment of the present invention;
fig. 3 is a schematic view of the structure of the deletion control section in fig. 1;
fig. 4 is a schematic view of the structure of the deletion control section in fig. 2;
in the figure: 1-gas sample introduction filter; 2/7/19/20-flow regulating valve; 3/8/30/31-flow meter; 4/9-primary pressure-stabilizing valve; 5/10-secondary pressure-stabilizing valve; 6-six-way valve; 12/13-pre-concentration column cooling fan; 14-three-stage pre-concentration column; 32-pre-concentration heater; 17/24-three-way valve; 16/18-on-off valve; 21-column heater; 22-chromatographic column cooling temperature-regulating fan; 23-gas chromatography column; 25-sensor temperature control device; 26-array sensing detector; 27-sensing signal acquisition card; 28-check valve; 11-flow display module; 15-temperature control display module; 29-control Module; 33-sampling diaphragm pump.
Detailed Description
The following describes embodiments of the present invention in further detail with reference to the accompanying drawings.
Referring to fig. 1 to 4, the invention discloses an array sensing chromatographic detector capable of detecting various gases, which is divided into 4 subsystems, namely an online enrichment preconcentration system, a front-end micro chromatographic separation system, a micro sensor array detector system and a data acquisition and analysis system.
The array sensing chromatographic detector mainly comprises a gas sampling filter 1, a flow regulating valve 2/7/19/20, a primary pressure stabilizing valve 4/9, a secondary pressure stabilizing valve 5/10 and a six-way valve 6; the system comprises a pre-concentration column cooling system (a pre-concentration column cooling fan 12/13), a three-stage pre-concentration column 14, a pre-concentration heating system (a pre-concentration heater 32), three-way valves 17/24, switching valves 16/18, a chromatographic column temperature control system (a chromatographic column heater 21 and a chromatographic column cooling temperature-adjusting fan 22), a gas chromatographic column 23, an array sensing detector 26, a sensing signal acquisition card 27, a check valve 28, a flow display module 11, a temperature control display module 15, a control module 29 and a sampling diaphragm pump 33.
The online enrichment pre-concentration system is mainly characterized in that the concentration of VOCs gas in the environment is low, but the precision of the sensor cannot reach the lower limit of gas detection at the same time, and the pre-concentration of the sample gas is required to be carried out to reach the lower limit of detection, so that the multiple of the concentration of the VOCs of the sample gas is improved.
The front-end micro-chromatographic separation system is used for quickly separating certain characteristic gases of VOCs.
The micro sensor array detector system is a gas detector based on combination of a plurality of different micro gas sensors, and can be used for distinguishing and identifying gas types and concentrations simultaneously.
The data acquisition and analysis system is a software and hardware system for analyzing the acquired data.
The detector is divided into two working modes in the working process. The first is a sample pre-concentration mode, and the second is an analysis mode.
Each filtering, drying and purifying device is positioned in front of the quantitative ring and the chromatographic column and is used for filtering particles, moisture and other impurities in the sample gas, so that the stability and the dryness of the sample gas are ensured, and the main components of the sample gas are not damaged.
Each pressure stabilizing valve can be provided with an air pressure sensor for detecting the air pressure of the carrier gas so as to ensure that the carrier gas is stable and consistent.
The working principle is as follows: first, the sampling diaphragm pump 33 is turned on, and the sample pre-concentration mode is entered. At the moment, the sample gas sequentially enters a sample filter 1, a flow regulating valve 2, pressure stabilizing valves 4 and 5, and then enters a preconcentration system (a system consisting of various components with index numbers of 12, 13, 14 and 32) through a six-way valve 6. All of the above regulating devices, voltage stabilizing devices and temperature control devices are equipped with associated sensors and are programmed via control module 29. In particular, the preconcentration heater 32 of the preconcentration column is required to have a fast heating rate, which is controlled to be between 10-50 ℃/s. After passing through the three-stage pre-concentration column 14, the sample gas is discharged out of the system through a sampling pump (i.e., a sampling diaphragm pump 33). The time of sampling can be set by a program. Generally, between 10s-5min is recommended.
When the sample pre-concentration mode is completed, the six-way valve 6 is automatically switched to the analysis mode. In the analysis mode, the sampling pump is stopped and the pre-concentration heater 32 of the pre-concentration column is rapidly warmed up to the prescribed desorption temperature of 300 ℃, during which the on-off valve 18 is closed. After reaching the specified temperature, N 2 The carrier gas passes through the flow regulating valve 7, the first-stage pressure stabilizing valve 9 and the second-stage pressure stabilizing valve 10 in sequence, enters the third-stage pre-concentration column 14 at fixed flow and pressure, and is the same as the carrier gasTime-on-off valve 18 is opened, N 2 And the component of the VOCs to be detected is blown and desorbed from the pre-concentration column as the blowing carrier gas, and the duration of the process can be adjusted by a program. The preconcentration column is filled with three materials, which are respectively as follows: a grade 1 adsorbing material Carbopack B, a grade 2 adsorbing material Carbopack X, and a grade 3 adsorbing material carbopen 1000. The pre-concentration tube is designed to have an inner diameter<5mm; the length is 8-15cm; the stainless steel shell ensures good temperature resistance and thermal conductivity.
N 2 The carrier gas carries the VOCs gas into the gas chromatography column 23 for separation of the components. The chromatographic column used in the method is a benzene series capillary chromatographic column, and the working temperature is between 50 and 180 ℃. The temperature for this example was 80 ℃. To better separate each peak, we designed a bypass N 2 The gas circuit can be mixed with a gas circuit of a sample gas to be analyzed and then enters the chromatographic column together, so that the separation degree is improved, and the flow and the pressure of the gas circuit can be adjusted. The specific adjustment method is to adjust the flow control valves 19 and 20 to change the flow, and the flow ratio of this embodiment is 1. The gas to be detected finally enters an array sensing detector, and the temperature of the detector is controlled at 40 ℃. The array sensing detector consists of a photoion VOCs gas sensor, an EtOH chemical gas sensor, an ETO chemical gas sensor and 3 MOS gas sensors. The sensing acquisition frequency is acquired at least 10 times per second for a total of>60 times/s. And after the sensed data is acquired, the data enters an analysis system for analysis, a related map is drawn, and finally the identification of concentration and components is realized.
That is, in the sample pre-concentration mode, the gas to be measured (for example, the ambient air containing a small amount of VOCs) is pumped by the sampling diaphragm pump 33 to enter the gas sample filter 1 (for filtering a small amount of water vapor and fine particles), the first-stage pressure-stabilizing valve 4, and the second-stage pressure-stabilizing valve 5 in sequence, and then the components of the VOCs to be measured in the sample gas are concentrated in the third-stage pre-concentration column 14. The two-stage pressure stabilizing valve is mainly suitable for ensuring that gas enters the pre-concentration column to maintain a certain pressure, and the flow regulating valve in the gas path is used for regulating, controlling and collecting the flow of the gas path for subsequent calculation and analysis. The pre-concentration column adopts three-stage pre-concentration, and filling and adsorbing materials of each stage have difference and are used for ensuring that all effective components to be detected can be enriched. The temperature of the inlet air during concentration can be adjusted and controlled, and enrichment is generally carried out under normal temperature adjustment.
The pre-concentration mode is switched to the analysis mode by switching the six-way valve 6. In the analysis mode, the sampling pump stops sampling, and the temperature control system (pre-concentration heater 32) of the pre-concentration column is rapidly heated to a specified desorption temperature, wherein the temperature interval is 60-300 ℃, and the switch valve 18 is closed during the period. After reaching the specified temperature, N 2 And the component of the VOCs to be detected is blown and desorbed from the pre-concentration column as the blowing carrier gas, and the duration of the process can be adjusted by a program. N is a radical of hydrogen 2 The carrier gas carries the VOCs gas into the chromatography column for separation of the components. To better separate each peak, we designed a bypass N 2 The gas path (i.e. the path from the three-way valve 17 to the three-way valve 24 via the on-off valve 16, the flow regulating valve 20 and the flow meter 30) can be mixed with the sample gas path to be analyzed and then enter the gas chromatographic column 23, so that the separation degree is improved, and the flow rate and the pressure of the gas path can be adjusted. Accordingly, the gas chromatography column 23 is provided with a column heater 21 for adjusting the temperature and a column cooling tempering fan 22.
The gas to be detected finally enters an array sensing detector 26, the temperature of the detector can be controlled through a sensor temperature control device 25, 6 sensors are preliminarily designed, and the sensing acquisition frequency is acquired at least 10 times per second, and the total time is more than 60 times/s. The sensed data is collected by the sensing signal acquisition card 27 and then enters an analysis system for analysis, and a related spectrum is drawn, so that the identification of concentration and components is finally realized. In which an array sensing detector 26 is connected to a check valve 28.
Preferably, the array sensing detector 26 is an array sensing integration composed of several micro-VOCs gas sensors, including a semiconductor material VOCs gas sensor processed by MEMS, a chemical sensor, a micro-uv light ion VOCs gas sensor, a micro-infrared laser VOCs gas sensor, and the like, and particularly, the MEMS structure ensures a small volume of the array sensing detector.
An air filter membrane is arranged in the gas sampling filter 1 and used for filtering dust and water vapor in air and preventing pollution to a chromatographic column and a detector.
The flow regulating valve is used for controlling the subsequent airflow speed to be constant and consistent, and the stability and the test precision of the detector are improved.
The gas chromatography column 23 is preferably a micro-MEMS gas chromatography column or a capillary gas chromatography column.
The three-stage pre-concentration column 14 is a traditional concentrator or an MEMS micro concentrator, and the adsorbent material filled in the concentrator is a combination of a molecular sieve, tenax-TA and activated carbon Carbopack, which are single or multiple.
Wherein the bypass N 2 The flow ratio of the gas path and the analysis sample gas path can be adjusted to optimize the chromatographic peak separation degree. The method of adjustment is specifically to effect a change in flow by adjusting the flow regulating valves 19 and 20. The optimal flow ratio is between 0 and 5.
The detection method comprises the following steps:
1. gas to be detected (such as ambient air containing a small amount of VOCs) sequentially enters a gas sample introduction filter 1 (for filtering a small amount of water vapor and fine particles), a flow regulating valve 2, a flow meter 3, a first-stage pressure stabilizing valve 4 and a second-stage pressure stabilizing valve 5 through the pumping force of a sampling diaphragm pump 33, and then enters a three-stage pre-concentration column 14 through a six-way valve 6 to concentrate the components of the VOCs to be detected in the sample gas. The timing of the sampling can be controlled by a pre-programmed program. The longer the time, the greater the corresponding subsequent concentration factor, which also means that the detection accuracy can be higher.
2. After the pre-concentration of the analysis sample gas is completed, the detector enters an analysis mode through the switching of the six-way valve 6. In the analysis mode, the sampling pump stops sampling, the temperature control system of the pre-concentration column rapidly rises to the specified desorption temperature, the temperature interval is 60-300 ℃, and the switch valve 18 is closed during the period.
3. After reaching the specified temperature, N 2 The gas component to be detected is purged and desorbed from the pre-concentration column as a purging carrier gas, and the duration of the process can be adjusted. N is a radical of 2 The carrier gas carries the gas into the gas chromatography column 23Separation of the components is carried out. To better separate each peak, we designed a bypass N 2 And the gas circuit can be mixed with a sample gas circuit to be analyzed and then enters the chromatogram together, so that the separation degree is improved.
4. The gas to be detected finally enters the array sensing detector 26, the temperature of the detector can be controlled, 6 sensors are preliminarily designed, and the sensing acquisition frequency is acquired at least 10 times per second, and the total time is more than 60 times/s. And the sensed data enters an analysis workstation for analysis after being collected. Six chromatograms will appear in the analysis results. Because the sensors of each VOCs have certain differences, response spectrums measured by different sensors in the same time period can be learned by a machine to form a set of spectrum library. Through the difference of six chromatograms, the concentration and the component of VOCs substances can be finally judged.
The array sensing chromatographic detector capable of realizing the detection of various VOCs gases and the detection method thereof greatly reduce the number of chromatographic columns when various qualitative and quantitative gases need to be measured. The concentration of various gases is detected, and the separated VOCs gases can be qualitatively and quantitatively measured by adopting the array type sensor unit without independently separating each gas. The quantity of chromatographic columns is reduced, and qualitative and quantitative measurement of various VOCs gases can be realized.
The above-mentioned embodiments, objects, technical solutions and advantages of the present invention are further described in detail, it should be understood that the above-mentioned embodiments are only specific embodiments of the present invention, and are not intended to limit the present invention, and any modifications, equivalent substitutions, improvements and the like made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (12)

1. An array-sensing gas chromatograph for detecting a plurality of VOCs, comprising:
the gas inlet pipeline is used for introducing gas to be detected into the detector and is connected with a first port of the six-way valve (6), and a gas sample injection filter (1) is arranged on the first gas inlet pipeline; the second port of the six-way valve (6) is connected with the gas inlet of a gas preconcentration device, and the gas outlet of the gas preconcentration device is connected with the fifth port of the six-way valve; and
a will purge N 2 A second air inlet pipeline of the detector is introduced, the second air inlet pipeline is connected with a first port of a first three-way valve, and a third port of the first three-way valve is connected with a third port of the six-way valve; the second port of the first three-way valve is connected with the second port of the second three-way valve through a first switch valve; a third port of the second three-way valve is connected with a fourth port of the six-way valve through a second switch valve; a first port of the second three-way valve is connected with a gas chromatographic column (23), and the gas chromatographic column is connected with an array sensing detector; and
the negative pressure pump is connected with the sixth port of the six-way valve;
wherein, the first and the second end of the pipe are connected with each other,
the gas pre-concentration device is a three-stage pre-concentration column with a cooling system and a heating system, and the filling adsorbates of each stage of the three-stage pre-concentration column are different; the adsorption material filled in the third-stage pre-concentration column enricher is one or a combination of a plurality of molecular sieves, tenax-TA and activated carbon Carbopack;
the single group of array sensing detector consists of six sensors including a photoion VOCs gas sensor, an EtOH chemical gas sensor, an ETO chemical gas sensor and 3 MOS gas sensors;
the detector is in a sample pre-concentration mode, a first port and a second port of the six-way valve are communicated, a third port and a fourth port are communicated, and a fifth port and a sixth port are communicated;
when the detector is in an analysis mode, a first port of the six-way valve is communicated with a sixth port, a second port of the six-way valve is communicated with a third port of the six-way valve, and a fourth port of the six-way valve is communicated with a fifth port of the six-way valve; the first switch valve is opened, the second switch valve is closed, and the negative pressure pump is closed.
2. The array sensing gas chromatograph of claim 1, wherein the first three-way valve is configured to open when the first three-way valve is openA first flow regulating valve is arranged between the second port and the second port of the second three-way valve; a second flow regulating valve is arranged between the third port of the first three-way valve and the third port of the second three-way valve; n flowing from the first three-way valve to the second three-way valve to the gas chromatography column through the first flow regulating valve 2 Relative to N flowing to the gas chromatography column through the second flow regulating valve 2 The flow ratio is 0.
3. The array sensing gas chromatograph for detecting multiple VOCs according to claim 1, wherein said three-stage pre-concentration column has a desorption temperature of 60-300 ℃.
4. The array sensing gas chromatograph for detecting multiple gases with VOCs of claim 1, wherein said array sensing detector is coupled to a sensing signal acquisition card that converts physical signals to electrical signals.
5. The array sensing gas chromatograph for detecting multiple VOCs gases of claim 1, wherein the sensing acquisition frequency of a single sensor is greater than or equal to 10 times/second.
6. The array sensing gas chromatograph for detecting multiple VOCs gases of claim 1, wherein a primary pressure maintaining valve and a secondary pressure maintaining valve are arranged on the first gas inlet pipeline; and a primary pressure stabilizing valve and a secondary pressure stabilizing valve are arranged on the second air inlet pipeline.
7. The array sensing gas chromatograph of claim 1, wherein the gas chromatograph is a micro-MEMS gas chromatograph or a capillary gas chromatograph.
8. The array-sensor gas chromatograph for detecting multiple gases of VOCs according to claim 1, wherein an air filter membrane is disposed in the gas injection filter for filtering out dust and water vapor in the air.
9. The array-sensing gas chromatograph of claim 1, wherein the negative pressure pump is a sampling diaphragm pump.
10. A method for detecting a plurality of VOCs using the array-sensing gas chromatograph of any of claims 1-9, comprising the steps of:
(1) Pumping the gas to be detected through a negative pressure pump, sequentially entering a gas sample injection filter, a primary pressure stabilizing device and a secondary pressure stabilizing device, and then entering a pre-concentration device to concentrate the VOCs components to be detected in the sample gas; controlling sampling time through a prefabricated program, wherein the sampling time is in direct proportion to the concentration multiple and the detection precision; (2) After the pre-concentration of the analysis sample gas is finished, entering an analysis mode through the switching of a six-way valve; in an analysis mode, a negative pressure pump serving as a sampling pump stops sampling, a temperature control system of the pre-concentration device is rapidly heated to a specified desorption temperature, the temperature interval is 60-300 ℃, and the second switch valve is in a closed state during the period;
(3) After reaching a prescribed temperature, N 2 The gas component to be detected is swept and desorbed from the pre-concentration device as sweeping carrier gas, and the duration of the sweeping and desorbing process can be adjusted; n is a radical of hydrogen 2 The carrier gas carries gas to enter the gas chromatographic column for component separation; the working temperature of the gas chromatographic column is 50-180 ℃;
(4) And finally, the gas to be detected enters the array sensing detector with controllable temperature, and is analyzed in a form of a chromatographic chart after being collected according to the set collection frequency.
11. The method according to claim 10, wherein step (4) further comprises the step of determining the concentration and composition of the VOCs species by reference to a library of spectra.
12. The method of claim 10 for detecting multiple VOCsThe method is characterized by further comprising the step of setting and adjusting the bypass N 2 And a gas path, and mixing the gas path with a sample gas path to be analyzed and then feeding the mixture into the gas chromatographic column.
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