Greenhouse gas analysis system and analysis method thereof

Abstract

The invention discloses a greenhouse gas analysis system and an analysis method thereof.The greenhouse gas analysis system comprises a sample injection system, a chromatographic column separation system and a detection system, the chromatographic column separation system comprises a first chromatographic column, a second chromatographic column, a third chromatographic column and a fourth chromatographic column, and the detection system comprises a hydrogen flame ionization detector, a thermal conductivity detector and an electron capture detector; the first chromatographic column, the second chromatographic column and the third chromatographic column are connected in parallel, the third chromatographic column and the fourth chromatographic column are connected in series, the first chromatographic column is connected with the hydrogen flame ionization detector, the second chromatographic column is connected with the electron capture detector, and the fourth chromatographic column is connected with the thermal conductivity detector; according to the invention, detection and analysis of fluorine-containing gases such as methane, carbon dioxide, nitrous oxide and sulfur hexafluoride are realized by using different detectors and different principles, chromatographic signal response is completed through the signal output system, and sample detection and analysis are realized through data analysis and calculation. And accurate and reliable quantity value traceability is provided for monitoring the change characteristics of the concentration of the greenhouse gas in the atmospheric environment.

Description

Technical Field

[0001] The present invention relates to the technical field of greenhouse gas analysis, and in particular to a greenhouse gas analysis system and an analysis method thereof. Background Art

[0002] With the development of the world economy, the problem of global warming has attracted wide attention. The phenomena such as rising temperatures, rising sea levels, and frequent extreme climate events caused by climate warming will pose serious threats and catastrophic consequences to food security, water resource management, ecological systems, disaster prevention systems, and human health. Many scientists believe that the significant increase in greenhouse gas emissions leading to intensified greenhouse effects is an important cause of global warming. The main greenhouse gases in the atmospheric environment include: carbon dioxide, methane, nitrous oxide, ozone, sulfur hexafluoride, carbon tetrafluoride, and hydrofluorochlorocarbons, etc. Among them, the three main greenhouse gases, carbon dioxide, methane, and nitrous oxide, have a significant contribution to the increase in the global average temperature, and the proportion even exceeds 60%. In addition, according to the different potential impacts of different greenhouse gases on global warming, scientists have developed the global warming potential (GWP), a relative index for comparing the potential impacts of different greenhouse gases on global warming. This index takes carbon dioxide as the benchmark and compares the greenhouse effects of other greenhouse gases with that of carbon dioxide. The higher the value of GWP, the stronger the greenhouse effect of the gas and the greater its potential contribution to global warming. Through research, it is found that among numerous greenhouse gases, the global warming potential of sulfur hexafluoride is 24,000 times that of CO2, and since the lifespan of sulfur hexafluoride in the atmosphere can reach 2,300 years, it is also an important gas component causing greenhouse effects. Therefore, the gas components of methane, carbon dioxide, nitrous oxide, sulfur hexafluoride, and carbon tetrafluoride in the atmospheric environment have become the key monitoring objects of greenhouse gases in the field of environmental monitoring. In recent years, the analysis and detection methods and technologies for the above gas components have developed rapidly. The main analysis methods are the spectroscopic method of physical measurement means and the gas chromatography method of chemical composition analysis. The application of cavity ring-down spectroscopy can achieve rapid real-time on-line analysis and is often used for real-time monitoring of atmospheric pollutants at environmental monitoring stations. However, the optical method analysis has the disadvantages of expensive equipment, high operation and maintenance costs, and the need for multiple devices to jointly achieve monitoring for different components. Among them, the chemical method - gas chromatography analysis is a gas analysis method that is widely used, routine, and technically mature in laboratories. Therefore, by using different detectors of gas chromatographs, constructing a multi-type integrated detection gas chromatography analysis method for different types of greenhouse gases, and realizing the simultaneous detection of different types of greenhouse gases in the atmospheric environment, the detection cost can be effectively reduced, providing technical support for the quality control of atmospheric environmental monitoring. Summary of the Invention

[0003] The object of the present invention is to provide a greenhouse gas analysis system and its analysis method, so as to achieve the purpose of providing accurate and reliable value traceability for monitoring the change characteristics of greenhouse gas concentration in the atmospheric environment.

[0004] To achieve the above object, the present invention provides the following solutions: A greenhouse gas analysis system includes a sampling system, a chromatographic column separation system connected to the sampling system, and a detection system connected to the chromatographic column separation system. The chromatographic column separation system includes a first chromatographic column, a second chromatographic column, a third chromatographic column, and a fourth chromatographic column. The detection system includes a flame ionization detector, a thermal conductivity detector, and an electron capture detector. The first chromatographic column, the second chromatographic column, and the third chromatographic column are in parallel, and the fourth chromatographic column and the third chromatographic column are in series. Six-port valves are provided between the first chromatographic column, the second chromatographic column, and the third chromatographic column and the sampling system, and between the third chromatographic column and the fourth chromatographic column. The first chromatographic column is connected to the flame ionization detector, the second chromatographic column is connected to the electron capture detector, and the third chromatographic column and the fourth chromatographic column are connected to the thermal conductivity detector.

[0005] Preferably, the sampling system includes gas pipelines respectively connected to the first chromatographic column, the second chromatographic column, and the third chromatographic column, and a gas sampling valve and a precision gas flow controller provided on the gas pipelines.

[0006] Preferably, the gas pipelines are made of stainless steel.

[0007] Preferably, first quantitative loops, second quantitative loops, and third quantitative loops are respectively provided on the gas pipelines between the precision gas flow controller and the first chromatographic column, the second chromatographic column, and the third chromatographic column.

[0008] Preferably, the first quantitative loop, the second quantitative loop, and the third quantitative loop are all 5 ml quantitative loops.

[0009] Preferably, the parameters of the first chromatographic column are set as Agilent 19095P-M25 HP-PLOT AL2O3 50m; flow rate 7 ml / min; pressure 8.69 pis; average rate 48.8 cm / sec; retention time 1.7 minutes; the set parameters of the second chromatographic column are Agilent 19095P-Q03 PLOT Q; flow rate 7 ml / min; pressure 5.4 pis; average rate 66.5 cm / sec; retention time 0.37 minutes; the parameters of the third chromatographic column and the fourth chromatographic column are set as Agilent HQ+13X; packed column HQ+13X; column temperature: two-stage temperature rise 50°C - 80°C - 180°C.

[0010] Preferably, a forward injection port is provided on the gas pipeline before entering the first chromatographic column. The parameters of the forward injection port are set as follows: the temperature of the forward injection port is 150 °C, the pressure is 8.69 pis, the total flow rate is 80 ml / min, and the septum purge flow rate is 3 ml / min. A rear injection port is provided on the gas pipeline before entering the second chromatographic column. The parameters of the rear injection port are set as follows: the temperature of the rear injection port is 150 °C, the pressure is 5.43 pis, the total flow rate is 150 ml / min, and the septum purge flow rate is 3 ml / min.

[0011] A greenhouse gas analysis method includes the following steps: Step S1: Pass the gas sample through a pipeline and through a precision gas flow controller, and then enter the chromatographic column separation system after passing through the precision gas flow controller. Step S2: The sample gas entering through the forward injection port enters the first quantitative loop; the sample gas entering through the rear injection port enters the second quantitative loop; the sample gas passing through the auxiliary control system enters the third quantitative loop. Step S3: When the first electronic switch is turned on, the state of the six-way valve of the injection unit changes. The gas in the first quantitative loop is driven by the first carrier gas and enters the first chromatographic column for separation. The separated gas sample components enter the hydrogen flame ionization detector for detection. When the second electronic switch is turned on, the state of the six-way valve of the injection unit changes. The gas in the second quantitative loop is driven by the second carrier gas and enters the second chromatographic column for separation. The separated gas sample components enter the electron capture detector for detection. When the third electronic switch is turned on, the gas drive valve controls the switch, and the sample in the third quantitative loop is loaded into the third chromatographic column for pre-separation by the third carrier gas. The gas sample is driven by the carrier gas and enters the fourth chromatographic column, and the separated components enter the thermal conductivity detector for detection. Step S4: Return to the sample loading state and prepare for the analysis of the next sample.

[0012] Preferably, the first carrier gas is nitrogen, the second carrier gas is methane in argon, and the third carrier gas is argon.

[0013] The present invention has achieved the following technical effects compared with the prior art: In view of the existing technological gap, the present invention applies a triple-detector gas chromatograph to establish an integrated conventional key monitoring greenhouse gas analysis system and method based on gas chromatography technology. It is characterized in that it can achieve a single injection. According to the different physical and chemical properties of greenhouse gases, through a multi-position gas control valve and a chromatographic column separation system, it is introduced into three different detectors of a gas chromatograph, namely a flame ionization detector, a thermal conductivity detector, and an electron capture detector, to complete the simultaneous detection and analysis of multiple key greenhouse gases such as CH4, CO2, N2O, SF6, etc., providing technical support for the rapid and accurate detection and analysis of the concentrations of key monitored greenhouse gases in the atmospheric environment. Relying on the analysis method established by this system, the quality control and value verification of relevant standard gas samples in the field of greenhouse gas atmospheric environment monitoring can be achieved, providing accurate and reliable value traceability for monitoring the variation characteristics of greenhouse gas concentrations in the atmospheric environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0015] Figure 1 is the system diagram of the present invention; Figure 2 is the schematic diagram of the injection system of the present invention; Among them, 1, six-way valve; 2, thermal conductivity detector; 3, electron capture detector; 4, flame ionization detector; 5, first chromatographic column; 6, second chromatographic column; 7, fourth chromatographic column; 8, third chromatographic column. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0016] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the protection scope of the present invention.

[0017] The object of the present invention is to provide a greenhouse gas analysis system and its analysis method to achieve the purpose of providing accurate and reliable value traceability for monitoring the variation characteristics of greenhouse gas concentrations in the atmospheric environment.

[0018] In order to make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below with reference to the drawings and specific embodiments.

[0019] Reference Figures 1 to 2, a greenhouse gas analysis system, comprising a sampling system, a chromatographic column separation system connected to the sampling system, and a detection system connected to the chromatographic column separation system. The chromatographic column separation system includes a first chromatographic column, a second chromatographic column, a third chromatographic column, and a fourth chromatographic column. The detection system includes a flame ionization detector, a thermal conductivity detector, and an electron capture detector. The first chromatographic column, the second chromatographic column, and the third chromatographic column are in parallel, and the fourth chromatographic column and the third chromatographic column are in series. Six-port valves are provided between the first chromatographic column, the second chromatographic column, and the third chromatographic column and the sampling system, and between the third chromatographic column and the fourth chromatographic column. The first chromatographic column is connected to the flame ionization detector, the second chromatographic column is connected to the electron capture detector, and the fourth chromatographic column is connected to the thermal conductivity detector. In view of the existing technical blank, the present invention applies a triple-detector gas chromatograph to establish an integrated conventional key monitoring greenhouse gas analysis system and method based on gas chromatography technology. It is characterized in that it can achieve one-time sampling. According to the different physical and chemical properties of greenhouse gases, through a multi-position gas control valve and a chromatographic column separation system, the gas is introduced into three different detectors of a gas chromatograph, namely a flame ionization detector, a thermal conductivity detector, and an electron capture detector, to complete the simultaneous detection and analysis of multiple key greenhouse gases such as CH4, CO2, N2O, and SF6, providing technical support for the rapid and accurate detection and analysis of the concentrations of key greenhouse gases in the atmospheric environment. Relying on the analysis method established by this system, the quality control and value verification of relevant standard gas samples in the field of greenhouse gas atmospheric environment monitoring can be realized, providing accurate and reliable value traceability for monitoring the change characteristics of greenhouse gas concentrations in the atmospheric environment.

[0020] Among them, the flame ionization detector is used to detect the concentration of alkane gases such as CH4; the thermal conductivity detector is used to detect the concentration of inorganic gases such as CO2; the electron capture detector is used to detect the concentration of fluorine-containing gases such as N2O and SF6.

[0021] Furthermore, the sample to be measured (bottled gas needs to be connected using a gas pressure reducing valve) is connected to a gas sampling valve and a precision gas flow controller through a stainless steel gas pipeline. The precision gas flow controller can control the flow rate of the sampling gas to achieve the dynamic balance of the sampling gas in a short time. The gas flowing out of the precision gas flow controller passes through a four-port valve and is connected to the injection port.

[0022] Reference Figure 2 , first quantitative loops, second quantitative loops, and third quantitative loops are respectively provided on the gas pipelines between the precision gas flow controller and the first chromatographic column, the second chromatographic column, and the third chromatographic column.

[0023] Furthermore, the first quantitative loop, the second quantitative loop, and the third quantitative loop are all 5 ml quantitative loops.

[0024] Further, the parameters of the first chromatographic column are set as Agilent 19095P-M25 HP-PLOT AL2O3 50m; flow rate 7 ml / min; pressure 8.69 pis; average rate 48.8 cm / sec; retention time 1.7 minutes; the set parameters of the second chromatographic column are Agilent 19095P-Q03 PLOT Q; flow rate 7 ml / min; pressure 5.4 pis; average rate 66.5 cm / sec; retention time 0.37 minutes; the parameters of the third chromatographic column and the fourth chromatographic column are set as Agilent HQ+13X; packed column HQ+13X; column temperature: two-stage temperature rise 50°C - 80°C - 180°C.

[0025] Further, a forward injection port is provided on the gas pipeline before entering the first chromatographic column, and the parameters of the forward injection port are set as forward injection port temperature 150°C, pressure 8.69 pis, total flow rate 80 ml / min, septum purge flow rate 3 ml / min; a rear injection port is provided on the gas pipeline before entering the second chromatographic column, and the parameters of the rear injection port are set as rear injection port temperature 150°C, pressure 5.43 pis, total flow rate 150 ml / min, septum purge flow rate 3 ml / min.

[0026] Reference Figure 2 , the forward injection port is connected to the A1 valve hole of the six-port valve through a stainless steel pipeline, the first quantitative tube is connected to the A3 valve hole and A6 valve hole of the six-port valve through a stainless steel pipeline, the A2 valve hole of the six-port valve is connected to the outside atmosphere through a stainless steel pipeline, the first carrier gas enters the A5 valve hole of the six-port valve through a stainless steel pipeline, and the A4 valve hole of the six-port valve A outputs the first gas sample; The rear injection port is connected to the B1 valve hole of the six-port valve through a stainless steel pipeline, the second quantitative tube is connected to the B3 valve hole and B6 valve hole of the six-port valve through a stainless steel pipeline, the B2 valve hole of the six-port valve is connected to the outside atmosphere through a stainless steel pipeline, the second carrier gas enters the B5 valve hole of the six-port valve through a stainless steel pipeline, and the B4 valve hole of the six-port valve B outputs the second gas sample; The third injection port is connected to the C1 valve hole of the six-port valve through a stainless steel pipeline, the third quantitative tube is connected to the C3 valve hole and C6 valve hole of the six-port valve through a stainless steel pipeline, the third carrier gas is connected to the C5 valve hole of the six-port valve through a stainless steel pipeline, the six-port valve C4 is connected to the PQ packed column, and through the six-port valve, it is connected to the D5 valve hole and D4 valve hole of the six-port valve, enters the 13X chromatographic column, and is connected to the D3 valve hole and D2 valve hole of the six-port valve through a stainless steel pipeline, and enters the thermal conductivity detector.

[0027] The gas sample to be measured passes through the injection port and enters different chromatographic columns through a multi-position pneumatic valve and a stainless-steel pipeline. According to the chemical properties and boiling points of the greenhouse gases to be analyzed, appropriate capillary columns and packed columns are selected. After establishing the separation of the multi-position chromatographic column combination, the gas enters three different detectors.

[0028] One end of the first chromatographic column is connected to the A4 valve hole of the six-port valve. After receiving the gas sample through the first capillary chromatographic column and separating the gas sample, it is output to the flame ionization detector. One end of the second chromatographic column is connected to the B4 valve hole of the six-port valve. After receiving the gas sample through the second capillary column and separating the second gas sample, it is output to the electron capture detector. One end of the third chromatographic column is respectively connected to the C4 valve hole of the six-port valve and is connected to the D5 valve hole of the six-port valve through a stainless-steel pipeline. The fourth chromatographic column is connected to the D4 and D3 valve holes of the six-port valve, and then passes through the D2 valve hole of the six-port valve through a stainless-steel pipeline and is output to the thermal conductivity detector.

[0029] The determination method and operation for simultaneously measuring atmospheric carbon dioxide, methane, and nitrous oxide are as follows: The system for simultaneously measuring atmospheric carbon dioxide, methane, and nitrous oxide has the following determination conditions: The column temperature is a two-stage programmed temperature rise. The initial temperature is 50 °C, it rises to 80 °C, and then rises to 180 °C again; the temperature of the flame ionization detector is 250 °C, the temperature of the electron capture detector is 300 °C, and the temperature of the thermal conductivity detector is 200 °C. The fuel gas for the flame ionization detector is high-purity hydrogen with a flow rate of 40 ml / min; the combustion-supporting gas is air with a flow rate of 400 ml / min; the carrier gas is high-purity nitrogen; the carrier gas for the electron capture detector is a methane-in-argon mixed gas, and the tail gas blow flow rate is 30 ml / min; the carrier gas for the thermal conductivity detector is argon, and the reference flow rate and tail gas blow flow rate are 45 ml / min.

[0030] It includes the following steps: Step S1: Pass the gas sample through a pipeline and through a precision gas flow controller, and then enter the chromatographic column separation system after the precision gas flow controller. Step S2: The sample gas entering through the front injection port enters the first quantitative loop; the sample gas entering through the rear injection port enters the second quantitative loop; the sample gas entering through the auxiliary control system enters the third quantitative loop. Step S3: When the first electronic switch is turned on, the state of the six-way valve in the sampling unit changes. The gas in the first quantitative loop enters the first chromatographic column under the drive of the first carrier gas and starts to separate. The separated gas sample components enter the hydrogen flame ionization detector for detection. When the second electronic switch is turned on, the state of the six-way valve in the sampling unit changes. The gas in the second quantitative loop enters the second chromatographic column under the drive of the second carrier gas and starts to separate. The separated gas sample components enter the electron capture detector for detection. When the third electronic switch is turned on, the gas drive valve controls the switch, and the sample in the third quantitative loop is loaded into the third chromatographic column for pre-separation by the third carrier gas. The gas sample enters the fourth chromatographic column under the drive of the carrier gas, and the separated components enter the thermal conductivity detector for detection. Step S4: Return to the sample loading state and prepare for the analysis of the next sample.

[0031] Further, the first carrier gas is nitrogen, the second carrier gas is methane in argon, and the third carrier gas is argon.

[0032] In the present invention, specific examples are used to elaborate on the principle and implementation manner of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention. At the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. A greenhouse gas analysis system, characterized in that, It includes an injection system, a chromatographic column separation system connected to the injection system, and a detection system connected to the chromatographic column separation system. The chromatographic column separation system includes a first chromatographic column, a second chromatographic column, a third chromatographic column, and a fourth chromatographic column. The detection system includes a flame ionization detector, a thermal conductivity detector, and an electron capture detector. The first chromatographic column, the second chromatographic column, and the third chromatographic column are in parallel, and the fourth chromatographic column and the third chromatographic column are in series. Six-port valves are provided between the first chromatographic column, the second chromatographic column, and the third chromatographic column and the injection system, and between the third chromatographic column and the fourth chromatographic column. The first chromatographic column is connected to the flame ionization detector, the second chromatographic column is connected to the electron capture detector, and the fourth chromatographic column is connected to the thermal conductivity detector.

2. The greenhouse gas analysis system according to claim 1, characterized in that, The injection system includes gas pipelines respectively connected to the first chromatographic column, the second chromatographic column, and the third chromatographic column, and a gas injection valve and a precision gas flow controller provided on the gas pipelines.

3. The greenhouse gas analysis system according to claim 2, wherein The gas pipelines are made of stainless steel.

4. The greenhouse gas analysis system according to claim 2, characterized in that, First quantitative loops, second quantitative loops, and third quantitative loops are respectively provided on the gas pipelines between the precision gas flow controller and the first chromatographic column, the second chromatographic column, and the third chromatographic column.

5. The greenhouse gas analysis system according to claim 4, wherein The first quantitative loop, the second quantitative loop, and the third quantitative loop are all 5 ml quantitative loops.

6. The greenhouse gas analysis system according to claim 1, wherein The parameters of the first chromatographic column are set as Agilent 19095P-M25 HP-PLOT AL2O3 50m; flow rate 7 ml / min; pressure 8.69 pis; average rate 48.8 cm / sec; residence time 1.7 minutes; the set parameters of the second chromatographic column are Agilent 19095P-Q03 PLOTQ; flow rate 7 ml / min; pressure 5.4 pis; average rate 66.5 cm / sec; residence time 0.37 minutes; the parameters of the third chromatographic column and the fourth chromatographic column are set as Agilent HQ+13X; packed column HQ+13X; column temperature: two-stage temperature rise 50°C - 80°C - 180°C.

7. The greenhouse gas analysis system according to claim 6, wherein, A forward injection port is provided on the gas pipeline before entering the first chromatographic column. The parameters of the forward injection port are set as forward injection port temperature 150°C, pressure 8.69 pis, total flow rate 80 ml / min, and septum purge flow rate 3 ml / min; a rear injection port is provided on the gas pipeline before entering the second chromatographic column. The parameters of the rear injection port are set as rear injection port temperature 150°C, pressure 5.43 pis, total flow rate 150 ml / min, and septum purge flow rate 3 ml / min.

8. A greenhouse gas analysis method, characterized in that, Applying the greenhouse gas analysis system according to any one of claims 1 to 7, comprising the following steps: Step S1: Pass the gas sample through a pipeline and through the precision gas flow controller, and enter the chromatographic column separation system after passing through the precision gas flow controller; Step S2: The sample gas entering through the forward injection port enters the first sampling loop; the sample gas entering through the rear injection port enters the second sampling loop; the sample gas passing through the auxiliary control system enters the third sampling loop; when the first electronic switch is turned on, the state of the six-way valve of the injection unit changes, and the gas in the first sampling loop enters the first chromatographic column under the drive of the first carrier gas for separation, and the separated gas sample components enter the hydrogen flame ionization detector for detection; when the second electronic switch is turned on, the state of the six-way valve of the injection unit changes, and the gas in the second sampling loop enters the second chromatographic column under the drive of the second carrier gas for separation, and the separated gas sample components enter the electron capture detector for detection; when the third electronic switch is turned on, the gas drive valve controls the switch, and the sample in the third sampling loop is loaded into the third chromatographic column for pre-separation through the third carrier gas; the gas sample enters the fourth chromatographic column under the drive of the carrier gas, and the separated components enter the thermal conductivity detector for detection; Step S3: Return to the sample loading state to prepare for the analysis of the next sample.

9. The greenhouse gas analysis method according to claim 8, wherein The first carrier gas is nitrogen, the second carrier gas is argon with methane, and the third carrier gas is argon.

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