Airborne gas flux detection device and method

Abstract

The invention provides an airborne gas flux detection device and method.The airborne gas flux detection device comprises an unmanned aerial vehicle and a detector, the detector comprises a first channel, a first flow cell and a first detector are arranged on the first channel, and the first detector is used for obtaining the concentration C1 of carbon dioxide in the first flow cell; the second channel and the first channel are arranged in parallel, and the carbon dioxide removal module, the methane enrichment module and the combustion furnace are respectively arranged on the second channel. The pretreatment unit is communicated with the first channel and the second channel and is used for removing water vapor in the mixed gas; the second detector is used for obtaining the concentration C2 of carbon dioxide in the gas after the water vapor is removed; and the calculation module is used for calculating the flux of carbon dioxide and methane according to the output values of the first detector and the second detector. The device has the advantages of simple structure and the like.

Description

Technical Field

[0001] The present invention relates to absorption spectroscopy, and in particular to an airborne gas flux detection device and method. Background Art

[0002] Due to the special application scenarios of airborne equipment, the weight of the equipment is required to be light, and the concentration of CH4 in the ambient air is low (generally in the range of 1.8-2.2 ppm), so the detection limit and precision of the equipment are required to be high. In the existing CH4 detection methods such as gas chromatography, cavity ring-down spectroscopy and off-axis integral cavity output spectroscopy, the detection equipment of such methods is heavy and costly, which cannot meet the detection needs of airborne equipment.

[0003] Water has a wide range of absorption peaks in the spectrum technology from microwave to far infrared bands, which will affect the measurement results of the target components. In fixed sites, a dehydration device based on the compressor refrigeration principle is usually added in front of the equipment to effectively remove the components in the air, but it is impractical to configure a high-power dehydration device in an airborne situation.

[0004] The existing UAV flux measurement technology is to configure a wind direction and speed analyzer and a concentration analyzer on the UAV, and then obtain the measurement results through an algorithm. However, there is a strong airflow disturbance during the flight of the UAV, which makes the measurement results of the wind direction and speed analyzer subject to significant interference, thereby affecting the final measurement results of the flux. Summary of the invention

[0005] In order to solve the deficiencies in the above-mentioned prior art solutions, the present invention provides an airborne gas flux detection device.

[0006] The objective of the present invention is achieved through the following technical solutions: An airborne gas flux detection device includes a drone and a detector, wherein the detector includes a first channel, a first flow cell and a first detector are arranged on the first channel, and the first detector is used to obtain a concentration C1 of carbon dioxide in the first flow cell; the detector also includes: a second channel, wherein the second channel is arranged in parallel with the first channel, and the carbon dioxide removal module, the methane enrichment module and the combustion furnace are respectively arranged on the second channel; A pre-processing unit, the pre-processing unit is connected to the first channel and the second channel to remove water vapor in the mixed gas; A second detector, the second detector is used to obtain the concentration C2 of carbon dioxide in the gas after water vapor is removed; A calculation module is used to calculate the flux of carbon dioxide and methane according to the output values ​​of the first detector and the second detector.

[0007] The present invention also aims to provide a gas flux detection method using a gas flux detection device, and the present invention aims to be achieved through the following technical solutions: Gas flux detection method, specifically: Drones carry detectors to collect samples in the air; Air enters the first flow cell in the first channel, and the first detector obtains the concentration C1 of carbon dioxide in the first flow cell; The air enters the second flow cell in the second channel, the air in the second flow cell passes through the carbon dioxide removal module and the methane enrichment module, and the enriched methane enters the combustion furnace for combustion; The gases in the first channel and the second channel are mixed and then sent to a pre-treatment unit to remove water vapor in the mixed gas; The second detector obtains the concentration C2 of carbon dioxide in the gas after water vapor is removed; The calculation module obtains the flux of carbon dioxide and methane according to the concentration C1 and the concentration C2.

[0008] Compared with the prior art, the present invention has the following beneficial effects: 1. Accurate results; Multi-stage dehumidification modules with different technologies are used to remove water vapor from the air, eliminating the influence of moisture on the measurement; Use calculation formulas to obtain more accurate fluxes of carbon dioxide and methane; 2. Simple structure and good reliability; The circulation pool, removal module, enrichment module, combustion furnace and water removal module are all mature technologies in this field, with simple structure and good reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The disclosure of the present invention will become easier to understand with reference to the accompanying drawings. It is easy for those skilled in the art to understand that these drawings are only used to illustrate the technical solution of the present invention and are not intended to limit the scope of protection of the present invention. In the drawings: Figure 1 1 is a simplified structural diagram of an airborne gas flux detection device according to the present invention. DETAILED DESCRIPTION

[0010] Figure 1 The following description describes optional specific embodiments of the present invention to teach those skilled in the art how to implement and reproduce the present invention. In order to teach the technical solution of the present invention, some conventional aspects have been simplified or omitted. Those skilled in the art will understand that variations or replacements derived from these specific embodiments will be within the scope of the present invention. Those skilled in the art will understand that the following features can be combined in various ways to form multiple variations of the present invention. Thus, the present invention is not limited to the following optional specific embodiments, but is only limited by the claims and their equivalents.

[0011] Example 1.

[0012] like Figure 1 As shown, the airborne gas flux detection device according to the embodiment of the present invention comprises: A drone and a detector, wherein the detector comprises a first channel, a first circulation pool 31 and a first detector 51 are arranged on the first circulation pool, and the first detector 51 is used to obtain the concentration C1 of carbon dioxide in the first circulation pool 31; The second channel is arranged in parallel with the first channel, and the second circulation pool 32, the carbon dioxide removal module 61, the methane enrichment module 62 and the combustion furnace 63 are respectively arranged on the second channel.

[0013] A pre-processing unit, the pre-processing unit is connected to the first channel and the second channel to remove water vapor in the mixed gas; A second detector 52, the second detector 52 is used to obtain the concentration C2 of carbon dioxide in the gas after the water vapor is removed; A calculation module is used to calculate the flux of carbon dioxide and methane according to the output values ​​of the first detector 51 and the second detector 52.

[0014] In order to accurately obtain the gas flux, the gas flux detection device further includes a height sensor, a temperature sensor and a water vapor sensor. The height sensor outputs the height H of the detector, the temperature sensor outputs the temperature T of the detector, and the water vapor sensor outputs the water vapor concentration C3 in the first circulation pool 31 or the second circulation pool 32; the fluxes of carbon dioxide and methane are: Carbon dioxide flux ; Methane flux ; V1 is the volume of the first flow cell 31, V2 is the volume of the second flow cell 32, S1 is the area of ​​the first flow cell 31, S2 is the area of ​​the second flow cell 32, g is the gravitational acceleration, M is the molecular weight of air, R is the ideal gas constant, is the rate of change of C1 concentration per unit time, is the rate of change per unit time at this concentration value.

[0015] In order to better remove water vapor and enrich methane, the pretreatment unit further includes a multi-stage water removal module 71, and the enrichment module 62 includes an adsorption and desorption module.

[0016] In order to accurately obtain the gas concentration, further, the first detector 51 and the second detector 52 are NDIR detectors.

[0017] The gas flux detection method of the embodiment of the present invention, that is, the working method of the gas flux detection device of the embodiment, is specifically as follows: Drones carry detectors to collect samples in the air; The air enters the first flow cell 31 in the first channel, and the first detector 51 obtains the concentration C1 of carbon dioxide in the first flow cell 31; The air enters the second flow cell 32 in the second channel, and the air in the second flow cell 32 passes through the carbon dioxide removal module 61 and the methane enrichment module 62, and the enriched methane enters the combustion furnace 63 for combustion; The gases in the first channel and the second channel are mixed and then sent to a pre-treatment unit to remove water vapor in the mixed gas; The second detector 52 obtains the concentration C2 of carbon dioxide in the gas after the water vapor is removed; The calculation module obtains the flux of carbon dioxide and methane according to the concentration C1 and the concentration C2.

[0018] In order to accurately obtain the gas flux, further, the flux of carbon dioxide and methane is: Carbon dioxide flux ; Methane flux ; V1 is the volume of the first flow cell 31, V2 is the volume of the second flow cell 32, S1 is the area of ​​the first flow cell 31, S2 is the area of ​​the second flow cell 32, g is the gravitational acceleration, M is the molecular weight of air, R is the ideal gas constant, is the rate of change of C1 concentration per unit time, is the rate of change per unit time at this concentration value.

[0019] Example 2.

[0020] An application example of the airborne gas flux detection device and method in Example 1 of the present invention.

[0021] In this application example, the drone is a multi-rotor drone. The detector, thermometer and altimeter are installed on the drone. The altimeter outputs the height H of the detector in the air, and the thermometer outputs the temperature T (in K) of the detector in the air. The first flow pool 31 and the second flow pool 32 are of the same size, with an area of ​​S and a volume of V respectively. like Figure 1 As shown, the first channel and the second channel are arranged in parallel, and the first switching module 21 uses a four-way valve. When it is switched, the air passes through the first flow controller 11 and selectively connects to the first channel or the second channel.

[0022] The first flow cell 31 and the first valve 41 are sequentially arranged on the first channel. The first detector 51 obtains the concentration C1 of carbon dioxide in the first flow cell 31 by using NDIR technology. The moisture sensor obtains the concentration C3 of water vapor in the first flow cell 31 .

[0023] The second channel is provided with a second circulation pool 32 (same as the first circulation pool 31), a second valve 42, a carbon dioxide removal module 61, a methane enrichment module 62 and a combustion furnace 63 in sequence. The methane enrichment module 62 enriches methane in the air by adsorption and desorption.

[0024] The pretreatment unit includes a third valve 43, a mixing tank 64, a second switching module 22, a multi-stage water removal module 71, a second flow controller 12 and a first pump 81 arranged in sequence. The third valve 43 connects the first channel and the second channel, and the second switching module 22 adopts a four-way valve, so that the outlet of the mixing tank 64 selectively connects to the outside or the multi-stage water removal module 71. In the multi-stage water removal module 71, the first stage 72 adopts the air-cooled water removal principle, and a fan is designed on the surface of the water removal module. The fan is surrounded by a multi-layer curved aluminum fine-diameter pipe. The sample gas passes through the pipe, and the fan blades rotate at high speed driven by the air flow disturbance, thereby achieving the cooling and water removal effect; the second stage 73 adopts a chemical desiccant, the third stage 74 adopts a physical desiccant, and the fourth stage 75 adopts a Nafion permeation tube. The multi-stage water removal module with different technical principles reduces the water content to below 0.05%, avoiding the influence of moisture on the measurement results. The baffle 91 and the second pump 82 are connected to the fourth stage 75.

[0025] The second detector 52 uses NDIR technology to obtain the concentration C2 of carbon dioxide in the mixed gas downstream of the pump.

[0026] Calculation module for obtaining carbon dioxide flux ; Methane flux ; V is the volume of the first flow cell 31 (or the second flow cell 32), S is the area of ​​the first flow cell 31 (or the second flow cell 32), g is the gravitational acceleration, M is the molecular weight of air, R is the ideal gas constant, is the rate of change of C1 concentration per unit time, is the rate of change per unit time at this concentration value.

[0027] The gas flux detection method of the embodiment of the present invention, that is, the working method of the gas flux detection device of the embodiment, is specifically as follows: The drone carries a detector for sampling in the air. The detector, thermometer and altimeter are installed on the drone. The altimeter outputs the height H of the detector in the air, which is 30 m. The thermometer outputs the temperature T of the detector in the air, which is 303.15 K. The first flow cell 31 and the second flow cell 32 are of the same size, with an area and volume of 10 cm respectively. 2 and 20 cm 3 ; The first flow controller 11 is turned on, the first switching module 21 is switched to state A, and the air enters the first circulation pool 31 through the first flow controller 11. After 0.5 seconds, the first switching module 21 is switched to state B, the first valve 41 is opened, and the concentration C1 of carbon dioxide in the first circulation pool 31 is obtained by the first detector 51, and the measured value is 470.2 µmol / mol. The moisture sensor obtains the concentration C3 of water vapor in the first circulation pool 31, and the measured value is 40.1 mmol / mol.

[0028] The first switching module 21 switches to the B state, and the air enters the second circulation pool 32. After 0.5 seconds, the first flow controller 11 is closed, the second valve 42 is opened, and the air passes through the carbon dioxide removal module 61, the methane enrichment module 62 and the combustion furnace 63 respectively, and the third valve 43 is opened. The first channel and the second channel enter the mixing pool 64 to be fully mixed, and then the second switching module 22 switches to the B state, and the mixed gas passes through the multi-stage water removal module 71, and after the first-stage water removal, the second-stage water removal, the third-stage water removal and the fourth-stage water removal, the water content of the gas is reduced to less than 0.05%.

[0029] The second flow controller 12 is opened, and the gas enters the second detector 52 to obtain the concentration C2 of carbon dioxide, which is measured to be 472.1 µmol / mol.

[0030] Calculation module for obtaining carbon dioxide flux ; Methane flux ; V is the volume of the first flow cell 31 (or the second flow cell 32), S is the area of ​​the first flow cell 31 (or the second flow cell 32), and g is the gravitational acceleration, 9.80 m / s 2 , M is the molecular weight of air, calculated as 29, P0 is the standard atmospheric pressure, calculated as 101.325 kPa, and R is the ideal gas constant, calculated as 8.314 Pa·m 3 ·K -1 ·mol -1 , is the rate of change of C1 concentration per unit time, is the rate of change per unit time at this concentration value.

[0031] The measured actual values ​​are substituted into the above calculation formula to obtain the carbon dioxide flux F1 and methane flux F2 respectively: F1 = 12.32 μmol m -2 s -1 .

[0032] F2 = 0.8 μmol m -2 s -1 .

[0033] Example 3.

[0034] According to the application example of the airborne gas flux detection device and method in Example 1 of the present invention, the difference from Example 2 is that: there is no need to use the first switching module, and the volumes of the first circulation cell 31 and the second circulation cell 32 are different.

[0035] In this application example, air enters the first channel and the second channel simultaneously after passing through the first flow controller 11 .

[0036] In the first channel, air flows through the first circulation pool 31 and the first valve 41 in sequence. The first detector 51 obtains the concentration C1 of carbon dioxide in the first circulation pool 31 by using NDIR technology. The moisture sensor obtains the concentration C3 of water vapor in the first circulation pool 31 .

[0037] The second channel flows through the second circulation pool 32, the second valve 42, the carbon dioxide removal module 61, the methane enrichment module 62 and the combustion furnace 63 in sequence. The methane enrichment module 62 enriches the methane in the air by adsorption and desorption.

[0038] The pretreatment unit includes a third valve 43, a mixing tank 64, a second switching module 22, a multi-stage water removal module 71, a second flow controller 12 and a first pump 81 which are arranged in sequence. The third valve 43 connects the first channel and the second channel, and the second switching module 22 switches so that the mixing tank 64 is connected to the multi-stage water removal module 71. In the multi-stage water removal module 71, the first stage 72 adopts the air cooling water removal principle, the second stage 73 adopts a chemical desiccant, the third stage 74 adopts a physical desiccant, and the fourth stage 75 adopts a Nafion permeation tube. The multi-stage water removal module with different technical principles reduces the water content to below 0.05%, thereby avoiding the influence of water on the measurement results. The baffle 91 and the second pump 82 are connected to the fourth stage 75.

[0039] The second detector 52 uses NDIR technology to obtain the concentration C2 of carbon dioxide in the mixed gas downstream of the pump.

[0040] Calculation module for obtaining carbon dioxide flux ; Methane flux ; V1 is the volume of the first flow cell 31, V2 is the volume of the second flow cell 32, S1 is the area of ​​the first flow cell 31, S2 is the area of ​​the second flow cell 32, g is the gravitational acceleration, M is the molecular weight of air, R is the ideal gas constant, is the rate of change of C1 concentration per unit time, is the rate of change per unit time at this concentration value.

[0041] The gas flux detection method of the embodiment of the present invention, that is, the working method of the gas flux detection device of the embodiment, is specifically as follows: The drone carries the detector to collect samples in the air. The altimeter outputs the height H of the detector in the air, which is 30 m. The thermometer outputs the temperature of the flow cell 31 and the flow cell 32, which is 303.15 K. The area and volume of the first flow cell 31 are 10 cm 2 and 20 cm 3 The area and volume of the second flow cell 32 are 15 cm 2 and 30 cm 3 ; The first flow controller 11 is opened, and the air enters the first circulation cell 31 and the second circulation cell 32 through the first flow controller 11 at the same time. The first valve 41 is opened, and the concentration C1 of carbon dioxide in the first circulation cell 31 is obtained by the first detector 51, and the measured value is 470.2 µmol / mol. The moisture sensor obtains the concentration C3 of water vapor in the first circulation cell 31, and the measured value is 40.1 mmol / mol.

[0042] The second valve 42 is opened, and the air passes through the carbon dioxide removal module 61, the methane enrichment module 62 and the combustion furnace 63 respectively, and the third valve 43 is opened. The first channel and the second channel enter the mixing pool 64 for full mixing, and then the second switching module 22 is switched to the B state, and the mixed gas passes through the multi-stage water removal module 71, and after the first-stage water removal, the second-stage water removal, the third-stage water removal and the fourth-stage water removal, the water content of the gas is reduced to less than 0.05%.

[0043] The second flow controller 12 is opened, and the gas enters the second detector 52 to obtain the concentration C2 of carbon dioxide, which is measured to be 472.1 µmol / mol.

[0044] Calculation module for obtaining carbon dioxide flux ; Methane flux ; V1 is the volume of the first flow cell 31, V2 is the volume of the second flow cell 32, S1 is the area of ​​the first flow cell 31, S2 is the area of ​​the second flow cell 32, g is the gravitational acceleration, M is the molecular weight of air, R is the ideal gas constant, is the rate of change of C1 concentration per unit time, is the rate of change per unit time at this concentration value.

[0045] Substituting the above test results into the above formula, the carbon dioxide flux F1 and methane flux F2 are obtained respectively: F1 = 12.32 μmol m -2 s -1 .

[0046] F2 = 0.8 μmol m -2 s -1 .

Claims

1. An airborne gas flux detection device, comprising a drone and a detector, wherein the detector comprises a first channel, a first flow cell and a first detector are arranged on the first channel, and the first detector is used to obtain a concentration C1 of carbon dioxide in the first flow cell; characterized in that: The detector also includes: a second channel, wherein the second channel is arranged in parallel with the first channel, and the carbon dioxide removal module, the methane enrichment module and the combustion furnace are respectively arranged on the second channel; A pre-processing unit, the pre-processing unit is connected to the first channel and the second channel to remove water vapor in the mixed gas; A second detector, the second detector is used to obtain the concentration C2 of carbon dioxide in the gas after water vapor is removed; A calculation module is used to calculate the flux of carbon dioxide and methane according to the output values ​​of the first detector and the second detector.

2. The airborne gas flux detection device according to claim 1, characterized in that: The gas flux detection device also includes a height sensor, a temperature sensor and a water vapor sensor. The height sensor outputs the height H of the detector, the temperature sensor outputs the temperature T of the detector, and the water vapor sensor outputs the water vapor concentration C3 in the first flow cell or the second flow cell. The fluxes of carbon dioxide and methane are: Carbon dioxide flux ; Methane flux ; V1 is the volume of the first flow cell, V2 is the volume of the second flow cell, S1 is the area of ​​the first flow cell, S2 is the area of ​​the second flow cell, P0 is the standard atmospheric pressure, g is the acceleration of gravity, M is the molecular weight of air, R is the ideal gas constant, is the rate of change of C1 concentration per unit time, is the rate of change per unit time at this concentration value.

3. The airborne gas flux detection device according to claim 2, characterized in that: The gas flux detection device also includes: A first switching module, the first switching module is used to make the sample gas selectively connect to the first channel or the second channel; A second switching module and a mixing pool, the mixing pool is connected to the first channel and the second channel, and the second switching module is used to make the outlet of the mixing pool selectively connected to the outside world or the pretreatment unit.

4. The airborne gas flux detection device according to claim 1, characterized in that: The pretreatment unit includes a multi-stage water removal module, and the enrichment module includes an adsorption and desorption module.

5. The airborne gas flux detection device according to claim 1, characterized in that: The first detector and the second detector are NDIR detectors.

6. The gas flux detection method of the gas flux detection device according to claim 1, specifically comprising: Drones carry detectors to collect samples in the air; Air enters the first flow cell in the first channel, and the first detector obtains the concentration C1 of carbon dioxide in the first flow cell; The air enters the second flow cell in the second channel, the air in the second flow cell passes through the carbon dioxide removal module and the methane enrichment module, and the enriched methane enters the combustion furnace for combustion; The gases in the first channel and the second channel are mixed and then sent to a pre-treatment unit to remove water vapor in the mixed gas; The second detector obtains the concentration C2 of carbon dioxide in the gas after water vapor is removed; The calculation module obtains the flux of carbon dioxide and methane according to the concentration C1 and the concentration C2.

7. The gas flux detection method according to claim 6, characterized in that: The fluxes of carbon dioxide and methane are: Carbon dioxide flux ; Methane flux ; V1 is the volume of the first flow cell, V2 is the volume of the second flow cell, S1 is the area of ​​the first flow cell, S2 is the area of ​​the second flow cell, P0 is the standard atmospheric pressure, g is the acceleration of gravity, M is the molecular weight of air, R is the ideal gas constant, is the rate of change of C1 concentration per unit time, is the rate of change per unit time at this concentration value.

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