A greenhouse gas analysis system and method of analysis thereof

Abstract

The application discloses a greenhouse gas analysis system and an analysis method thereof, which comprises a sample inlet 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. The detection system comprises a hydrogen flame ion 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 ion detector, the second chromatographic column is connected with the electron capture detector, and the fourth chromatographic column is connected with the thermal conductivity detector. The application realizes the detection and analysis of methane, carbon dioxide, nitrous oxide and fluorine-containing gases such as sulfur hexafluoride by using different principles of different detectors. Finally, the chromatographic signal response is completed through a signal output system, and sample detection and analysis are realized through data analysis and calculation, so that accurate and reliable value traceability is provided for the monitoring of the concentration change characteristics of atmospheric environment greenhouse gases.

Description

TECHNICAL FIELD

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

[0002] With the development of the world economy, global warming has attracted widespread attention. The phenomena caused by global warming, such as rising temperature, rising sea level, and frequent extreme weather events, will pose a serious threat and catastrophic consequences to food security, water resource management, ecological system, disaster prevention system, and human health. Many scientists believe that the intensification of greenhouse effect caused by the massive emission of greenhouse gases is an important reason for global warming. The main greenhouse gases in the atmospheric environment include carbon dioxide, methane, nitrous oxide, ozone, sulfur hexafluoride, carbon tetrafluoride, and hydrofluorochlorocarbon, among which the contribution of the three main greenhouse gases, carbon dioxide, methane, and nitrous oxide, to the increase of global average temperature is obvious, 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) as a relative index to compare the potential impacts of different greenhouse gases on global warming. The index takes carbon dioxide as the benchmark to compare the greenhouse effect of other greenhouse gases with that of carbon dioxide. The higher the value of GWP is, the stronger the greenhouse effect of the gas is, and the greater the potential contribution to global warming is. It is found through research that among many greenhouse gases, the global warming potential of sulfur hexafluoride is 24000 times that of CO2, and because the life of sulfur hexafluoride in the atmosphere can reach 2300 years, it is also an important gas composition that produces greenhouse effect. Therefore, the gas compositions 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-mentioned gas compositions have developed rapidly, among which the main analysis methods are physical measurement means of spectroscopy and chemical composition analysis of gas chromatography. The application of optical cavity ring-down spectroscopy can realize rapid real-time online analysis, and is commonly used for real-time monitoring of atmospheric pollutants in environmental monitoring stations. However, the optical method analysis has the disadvantages of expensive equipment, high operation and maintenance cost, and the need for multiple devices to monitor different components. The chemical method, i.e. gas chromatography analysis method, is a gas analysis method that is widely used in laboratories, conventional, and mature in technology. Therefore, by applying different detectors of gas chromatographs, establishing a multi-type integrated detection gas chromatography analysis method for different types of greenhouse gases, and realizing the simultaneous detection of different types of atmospheric environment greenhouse gases, the detection cost can be effectively reduced, and technical support can be provided for the quality control of atmospheric environment monitoring. SUMMARY

[0003] The greenhouse gas analysis system and the analysis method thereof can provide accurate and reliable value traceability for monitoring the concentration change characteristics of greenhouse gases in the atmospheric environment.

[0004] To achieve the above-mentioned purpose, the present application provides the following solutions.

[0005] A greenhouse gas analysis system comprises a sample injection system, a chromatographic column separation system connected with the sample injection system, and a detection system connected with the chromatographic column separation system, wherein the chromatographic column separation system comprises a first chromatographic column, a second chromatographic column, a third chromatographic column and a fourth chromatographic column, 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 fourth chromatographic column and the third chromatographic column are connected in series, six-way valves are arranged between the first chromatographic column, the second chromatographic column and the third chromatographic column and between the third chromatographic column and the fourth chromatographic column, 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 third chromatographic column and the fourth chromatographic column are connected with the thermal conductivity detector.

[0006] Preferably, the sample injection system comprises gas pipelines respectively connected with the first chromatographic column, the second chromatographic column and the third chromatographic column, and gas injection valves and precise gas flow controllers arranged on the gas pipelines.

[0007] Preferably, the gas pipelines are made of stainless steel.

[0008] Preferably, the precise gas flow controllers are respectively provided with first, second and third dosing rings on the gas pipelines between the first chromatographic column, the second chromatographic column and the third chromatographic column.

[0009] Preferably, the first, second and third dosing rings are all 5ml dosing rings.

[0010] Preferably, the first chromatographic column is set to Agilent 19095P-M25 HP-PLOT AL2O350m, the flow rate is 7ml / min, the pressure is 8.69pis, the average rate is 48.8cm / sec, and the residence time is 1.7 minutes, the second chromatographic column is set to Agilent 19095P-Q03 PLOT Q, the flow rate is 7ml / min, the pressure is 5.4pis, the average rate is 66.5cm / sec, and the residence time is 0.37 minutes, and the third chromatographic column and the fourth chromatographic column are set to Agilent HQ+13X, the filled column is HQ+13X, and the column temperature is two-stage temperature rising from 50℃ to 80℃ to 180℃.

[0011] Preferably, a forward injection port is provided on the gas line before entering the first chromatographic column, and the parameters of the forward injection port are set as follows: 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 backward injection port is provided on the gas line before entering the second chromatographic column, and the parameters of the backward injection port are set as follows: backward injection port temperature 150°C, pressure 5.43 pis, total flow rate 150 ml / min, and septum purge flow rate 3 ml / min.

[0012] A method for analyzing greenhouse gases includes the following steps:

[0013] Step S1: Pass the gas sample through a pipeline and through a precision gas flow controller, and then into the chromatographic column separation system;

[0014] 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 entering through the auxiliary control system enters the third quantitative loop.

[0015] Step S3: 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 quantitative loop enters the first chromatographic column under the drive of the first carrier gas to begin separation. The separated gas sample components enter the 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 quantitative loop enters the second chromatographic column under the drive of the second carrier gas to begin 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 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.

[0016] Step S4: Return to sample loading state and prepare for the next sample analysis.

[0017] Preferably, the first carrier gas is nitrogen, the second carrier gas is argon-methane, and the third carrier gas is argon.

[0018] The present invention achieves the following technical effects compared to the prior art:

[0019] This invention addresses existing technological gaps by establishing an integrated routine key greenhouse gas monitoring analysis system and method based on gas chromatography technology using a three-detector gas chromatograph. Its key feature is the ability to achieve single-injection analysis of multiple key greenhouse gases, including CH4, CO2, N2O, and SF6. This is achieved through a multi-position gas control valve and chromatographic column separation system, targeting the different physicochemical properties of various greenhouse gases, and simultaneously detecting and analyzing these gases using three different gas chromatograph detectors: a flame ionization detector, a thermal conductivity detector, and an electron capture detector. This provides technical support for the rapid and accurate detection and analysis of key greenhouse gas concentrations in the atmospheric environment. The analytical method established by this system enables quality control and metrological verification of relevant standard gas samples in the field of greenhouse gas atmospheric environmental monitoring, providing accurate and reliable metrological traceability for monitoring the characteristics of greenhouse gas concentration changes in the atmospheric environment. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Fig. 1 This is a system diagram of the present invention;

[0022] Fig. 2 This is a schematic diagram of the sample introduction system of the present invention;

[0023] Among them, 1. six-way valve; 2. thermal conductivity detector; 3. electron capture detector; 4. hydrogen flame detector; 5. first chromatographic column; 6. second chromatographic column; 7. fourth chromatographic column; 8. third chromatographic column. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] The purpose of this invention is to provide a greenhouse gas analysis system and analysis method, so as to provide accurate and reliable traceability of values ​​for monitoring the characteristics of changes in greenhouse gas concentrations in the atmospheric environment.

[0026] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0027] refer to Figs. 1-2 A greenhouse gas analysis system 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 column, a second column, a third column, and a fourth column. The detection system includes a flame ionization detector, a thermal conductivity detector, and an electron capture detector. The first, second, and third columns are connected in parallel, and the fourth column is connected in series with the third column. Six-way valves are provided between the first, second, and third columns and the injection system, as well as between the third and fourth columns. The first column is connected to the flame ionization detector, the second column is connected to the electron capture detector, and the fourth column is connected to the thermal conductivity detector. This invention addresses a technological gap by applying a three-detector gas chromatograph to establish an integrated routine key monitoring greenhouse gas analysis system and method based on gas chromatography technology. Its key feature is that it enables single-injection analysis of multiple key greenhouse gases, including CH4, CO2, N2O, and SF6, by employing a multi-position gas control valve and chromatographic column separation system. These gases are introduced into three different gas chromatograph detectors: a flame ionization detector, a thermal conductivity detector, and an electron capture detector. This provides technical support for the rapid and accurate detection and analysis of key greenhouse gas concentrations in atmospheric environmental monitoring. The analytical methods established by this system enable quality control and metrological verification of relevant standard gas samples in the field of greenhouse gas atmospheric environmental monitoring, providing accurate and reliable metrological traceability for monitoring the characteristics of changes in atmospheric greenhouse gas concentrations.

[0028] Among them, the hydrogen 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; and the electron capture detector is used to detect the concentration of fluorine-containing gases such as N2O and SF6.

[0029] Furthermore, the sample to be tested (bottled gas requires a gas pressure reducing valve for connection) is connected to the gas injection valve and precision gas flow controller via a stainless steel gas pipeline. The precision gas flow controller enables control of the injection gas flow rate, achieving dynamic equilibrium of the injection gas over a short period. The gas exiting the precision gas flow controller is then connected to the injection port via a four-way valve.

[0030] refer to Fig. 2 The precision gas flow controller is provided with a first metering loop, a second metering loop, and a third metering loop on the gas pipeline between the first chromatographic column, the second chromatographic column, and the third chromatographic column, respectively.

[0031] Furthermore, the first, second, and third quantitative loops are all 5 ml quantitative loops.

[0032] Furthermore, the parameters of the first chromatographic column were set as follows: Agilent 19095P-M25 HP-PLOT AL2O3 50m; flow rate 7ml / min; pressure 8.69pis; average velocity 48.8cm / sec; residence time 1.7min; the parameters of the second chromatographic column were set as follows: Agilent 19095P-Q03 PLOT Q; flow rate 7ml / min; pressure 5.4pis; average velocity 66.5cm / sec; residence time 0.37min; the parameters of the third and fourth chromatographic columns were set as follows: Agilent HQ+13X; packed column HQ+13X; column temperature: second-stage temperature ramp 50℃-80℃-180℃.

[0033] Furthermore, a forward injection port is provided on the gas line before entering the first chromatographic column. The parameters of the forward injection port are set as follows: forward injection port temperature 150℃, pressure 8.69 pis, total flow rate 80 ml / min, and septum purge flow rate 3 ml / min. A backward injection port is provided on the gas line before entering the second chromatographic column. The parameters of the backward injection port are set as follows: backward injection port temperature 150℃, pressure 5.43 pis, total flow rate 150 ml / min, and septum purge flow rate 3 ml / min.

[0034] refer to Fig. 2 The forward sample port is connected to the A1 valve port of the six-way valve through a stainless steel pipeline. The first quantitative tube is connected to the A3 and A6 valve ports of the six-way valve through a stainless steel pipeline. The A2 valve port of the six-way valve is connected to the outside atmosphere through a stainless steel pipeline. The first carrier gas enters the A5 valve port of the six-way valve through a stainless steel pipeline. The first gas sample is output from the A4 valve port of the six-way valve A.

[0035] The rear injection port is connected to the B1 valve port of the six-way valve through a stainless steel pipeline. The second quantitative tube is connected to the B3 and B6 valve ports of the six-way valve through a stainless steel pipeline. The B2 valve port of the six-way valve is connected to the outside atmosphere through a stainless steel pipeline. The second carrier gas enters the B5 valve port of the six-way valve through a stainless steel pipeline. The second gas sample is output from the B4 valve port of the six-way valve.

[0036] The third injection port is connected to the C1 port of the six-way valve via a stainless steel pipeline. The third quantitative tube is connected to the C3 and C6 ports of the six-way valve via a stainless steel pipeline. The third carrier gas is connected to the C5 port of the six-way valve via a stainless steel pipeline. The C4 port of the six-way valve is connected to the PQ packed column. The gas enters the 13X column via the six-way valve and is connected to the D5 and D4 ports of the six-way valve via a stainless steel pipeline. The gas then enters the thermal conductivity detector.

[0037] The gas sample to be tested enters different chromatographic columns through the injection port, multi-position pneumatic valve and stainless steel pipeline. Based on the chemical properties and boiling point of the greenhouse gas being analyzed, appropriate capillary columns and packed columns are selected to establish a multi-position chromatographic column combination for separation, and then the gas enters three different types of detectors.

[0038] One end of the first chromatographic column is connected to the A4 valve port of the six-way valve. After receiving the gas sample through the first capillary chromatographic column and separating the gas sample, the gas sample is output to the hydrogen flame detector.

[0039] One end of the second chromatographic column is connected to the B4 valve port of the six-way valve. The gas sample is received through the second capillary column and separated, and then output to the electron capture detector.

[0040] One end of the third chromatographic column is connected to the C4 valve port of the six-way valve, and then connected to the D5 valve port of the six-way valve through a stainless steel pipeline.

[0041] The fourth chromatographic column is connected to the D4 and D3 valve ports of the six-way valve, and then outputs to the thermal conductivity detector through the D2 valve port of the six-way valve and a stainless steel pipeline.

[0042] Methods and procedures for simultaneously determining atmospheric carbon dioxide, methane, and nitrous oxide:

[0043] Simultaneous determination of atmospheric carbon dioxide, methane, and nitrous oxide under the following conditions: chromatographic column temperature was programmed in two stages, starting at 50°C, increasing to 80°C, and then further increasing to 180°C; the flame ionization detector (FID) temperature was 250°C, the electron capture detector (ECD) temperature was 300°C, and the thermal conductivity detector (TCD) temperature was 200°C. The FID was powered by high-purity hydrogen at a flow rate of 40 ml / min; the oxidant was air at a flow rate of 400 ml / min; and the carrier gas was high-purity nitrogen. The ECD carrier gas was an argon-methane mixture at a make-up flow rate of 30 ml / min. The TCD carrier gas was argon, with a reference flow rate and a make-up flow rate of 45 ml / min.

[0044] Includes the following steps:

[0045] Step S1: Pass the gas sample through a pipeline and through a precision gas flow controller, and then into the chromatographic column separation system;

[0046] 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 entering through the auxiliary control system enters the third quantitative loop.

[0047] Step S3: 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 quantitative loop enters the first chromatographic column under the drive of the first carrier gas to begin separation. The separated gas sample components enter the 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 quantitative loop enters the second chromatographic column under the drive of the second carrier gas to begin 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 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.

[0048] Step S4: Return to sample loading state and prepare for the next sample analysis.

[0049] Furthermore, the first carrier gas is nitrogen, the second carrier gas is argon-methane, and the third carrier gas is argon.

[0050] Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. Furthermore, those skilled in the art will recognize that, based on the ideas of this invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. A greenhouse gas analysis system, characterized in that, The system 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 column, a second column, a third column, and a fourth column. The detection system includes a flame ionization detector, a thermal conductivity detector, and an electron capture detector. The first, second, and third columns are connected in parallel, and the fourth column is connected in series with the third column. A six-way valve is provided between the first, second, and third columns and the injection system, as well as between the third and fourth columns. The first column is connected to the flame ionization detector, the second column is connected to the electron capture detector, and the fourth column is connected to the thermal conductivity detector. The injection system includes gas lines connected to the first chromatographic column, the second chromatographic column, and the third chromatographic column, respectively, as well as a gas injection valve and a precision gas flow controller disposed on the gas lines; a first quantitative loop, a second quantitative loop, and a third quantitative loop are respectively disposed on the gas lines between the precision gas flow controller and the first chromatographic column, the second chromatographic column, and the third chromatographic column. The first, second, and third quantitative loops are all 5 ml quantitative loops.

2. The greenhouse gas analysis system according to claim 1, characterized in that, The gas pipeline is made of stainless steel.

3. The greenhouse gas analysis system according to claim 1, characterized in that, The parameters for the first chromatographic column were set as follows: Agilent 19095P-M25HP-PLOTAL2O350m; flow rate 7ml / min; pressure 8.69pis; average velocity 48.8cm / sec; residence time 1.7min; and the parameters for the second chromatographic column were set as follows: Agilent 19095P-Q03PLOTQ; flow rate 7ml / min; pressure 5.4pis; average velocity 66.5cm / sec. The residence time was 0.37 minutes; the parameters of the third and fourth columns were set to Agilent HQ+13X; the packed column was HQ+13X. Column temperature: Second-stage heating from 50℃ to 80℃ to 180℃.

4. The greenhouse gas analysis system according to claim 3, characterized in that, A forward injection port is provided on the gas line before the first chromatographic column. The parameters of the forward injection port are set as follows: forward injection port temperature 150℃, pressure 8.69 pis, total flow rate 80 ml / min, and septum purge flow rate 3 ml / min. A backward injection port is provided on the gas line before the second chromatographic column. The parameters of the backward injection port are set as follows: backward injection port temperature 150℃, pressure 5.43 pis, total flow rate 150 ml / min, and septum purge flow rate 3 ml / min.

5. A method for analyzing greenhouse gases, characterized in that, The greenhouse gas analysis system according to any one of claims 1 to 4 includes the following steps: Step S1: Pass the gas sample through a pipeline and through a precision gas flow controller, and then into the chromatographic column separation system; Step S2: Sample gas entering through the inlet enters the first quantitative loop; sample gas entering through the outlet enters the second quantitative loop; sample gas entering through the auxiliary control system enters the third quantitative 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 quantitative loop enters the first chromatographic column under the drive of the first carrier gas to begin separation, and the separated gas sample components enter the 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 quantitative loop enters the second chromatographic column under the drive of the second carrier gas to begin 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 quantitative 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 sample loading state and prepare for the next sample analysis.

6. The greenhouse gas analysis method according to claim 5, characterized in that, The first carrier gas is nitrogen, the second carrier gas is argon-methane, and the third carrier gas is argon.

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