Shipborne water-gas interface greenhouse gas flux detection device and method

Abstract

The invention relates to a spectrum technology, and particularly provides a shipborne water-gas interface greenhouse gas flux detection device and method.The detection device comprises a ship and a detector, the detector comprises a first channel, and a first flow cell and a first detector are arranged on the first channel; 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; the second flow cell, 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; the sensor obtains the temperature T and the water vapor pressure e above the water body; the calculation module is used for obtaining carbon dioxide flux and methane flux according to output values of the detector and the sensor. The device has the advantages of simple structure and the like.

Description

Technical Field

[0001] The invention relates to absorption spectroscopy, and in particular to a ship-borne water-air interface greenhouse gas flux detection device and method. Background Art

[0002] Currently, there is little research on carbon exchange at the water-air interface, and there is an even greater lack of fast-moving greenhouse gas flux detection devices, making it impossible to objectively evaluate the greenhouse gas flux at the water-air interface, making it difficult to fully assess the impact of lakes / oceans on the source and sink pattern of atmospheric greenhouse gases, which is not conducive to understanding the characteristics of my country's total greenhouse gas emissions and balances.

[0003] Water has a wide range of absorption peaks in the spectrum technology from microwave to far infrared bands, especially in detection environments with high water content such as lakes / oceans, and will have a more significant impact on the measurement results of the target components. In fixed sites, a dehydration device based on the compressor refrigeration principle is generally added in front of the equipment to effectively remove components in the air, but in ship-borne mobile devices, especially unmanned ships, it is impractical to equip them with high-power dehydration devices.

[0004] Existing greenhouse gas flux measurement technologies at the water-air interface are basically fixed detection technologies, such as the static box method, eddy correlation method, and gradient method. They have strict installation conditions and high requirements for the uniformity of the underlying surface, making it difficult to carry out mobile rapid detection. Greenhouse gas flux at the water-air interface is affected by environmental factors such as wind speed, pH value, water temperature, carbon content, algae and plant content, alkalinity, total nitrogen and total phosphorus, and has large spatial differences, so fixed detection does not cover the entire area.

[0005] Therefore, developing a mobile water-air interface greenhouse gas flux detection device and carrying out accurate mobile flux detection will provide new ideas for the study of carbon emissions in water bodies and will help to fully understand the absorption / emission of greenhouse gases at the water-air interface. Summary of the invention

[0006] In order to solve the deficiencies in the above-mentioned prior art solutions, the present invention provides a ship-borne water-air interface greenhouse gas flux detection device. The purpose of the present invention is achieved through the following technical solutions: A ship-borne water-air interface greenhouse gas flux detection device, comprising a ship 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 the concentration C1 of carbon dioxide in the first flow cell; the detector further comprises: The second channel is arranged in parallel with the first channel, and the second circulation pool, the carbon dioxide removal module, the methane enrichment module and the combustion furnace are respectively arranged on the second channel.

[0007] 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 the water vapor is removed; a sensor that acquires the temperature T and the water vapor pressure e above the body of water; A calculation module, the calculation module is used to calculate the carbon dioxide flux F1 and the methane flux F2 according to the output values ​​of the detector and the sensor; ; ; V1 and S1 are the volume and inner surface area of ​​the first flow cell, V2 and S2 are the volume and inner surface area of ​​the second flow cell, M CO2 is the molar mass of CO2, M CH4 is the molar mass of CH4, P0 is the standard atmospheric pressure, R is the ideal gas constant, C1 ′ is the rate of change of concentration C1 per unit time, (C2-C1) ′ It is the rate of change of (C2-C1) per unit time.

[0008] 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: The boat carries a detector to take samples above the water body; 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 the water vapor is removed; the sensor obtains the temperature T and the water vapor pressure e above the water body; The calculation module obtains the carbon dioxide flux F1 and the methane flux F2 according to the output values ​​of the detector and the sensor; ; ; V1 and S1 are the volume and inner surface area of ​​the first flow cell, V2 and S2 are the volume and inner surface area of ​​the second flow cell, M CO2 is the molar mass of CO2, M CH4is the molar mass of CH4, P0 is the standard atmospheric pressure, R is the ideal gas constant, C1 ′ is the rate of change of concentration C1 per unit time, (C2-C1) ′ It is the rate of change of (C2-C1) per unit time.

[0009] Compared with the prior art, the present invention has the following beneficial effects: 1. Accurate results; Use a wet-bulb manometer to measure the water vapor pressure e above the water body to avoid the problem of inaccurate direct measurement of water vapor concentration by a hygrometer in high temperature, high salt, and high humidity environments such as lakes / oceans; 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 carbon dioxide flux and methane flux; 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

[0010] 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 It is a simplified structural diagram of the ship-borne water-air interface greenhouse gas flux detection device according to the present invention.

[0011] In the accompanying drawings, 11-a first flow controller, 12-a second flow controller, 21-a first switching module, 22-a second switching module, 31-a first circulation pool, 32-a second circulation pool, 41-a first valve, 42-a second valve, 43-a third valve, 51-a first detector, 52-a second detector, 53-a sensor, 54-a calculation module, 61-a carbon dioxide removal module, 62-a methane enrichment module, 63-a combustion furnace, 64-a mixing pool, 71-a multi-stage water removal module, 72-a first stage, 73-a second stage, 74-a third stage, 75-a fourth stage, 81-a first pump, 82-a second pump, and 91-a flow control device. DETAILED DESCRIPTION

[0012] Figure 1The 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.

[0013] Example 1.

[0014] like Figure 1 As shown, a ship-borne water-air interface greenhouse gas flux detection device according to an embodiment of the present invention includes the following parts.

[0015] A ship and a detector, wherein the detector comprises a first channel, on which a first circulation pool 31 and a first detector 51 are arranged, and the first detector 51 is used to obtain the concentration C1 of carbon dioxide in the first circulation pool 31.

[0016] 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.

[0017] The pre-processing unit is connected to the first channel and the second channel to remove water vapor in the mixed gas.

[0018] The second detector 52 is used to obtain the concentration C2 of carbon dioxide in the gas after water vapor is removed.

[0019] The sensor 53 acquires the temperature T and the water vapor pressure e above the body of water.

[0020] The calculation module 54 is used to calculate the carbon dioxide flux F1 and the methane flux F2 according to the output values ​​of the first detector 51 , the second detector 52 and the sensor 53 .

[0021] .

[0022] .

[0023] V1 and S1 are the volume and inner surface area of ​​the first flow cell 31, V2 and S2 are the volume and inner surface area of ​​the second flow cell 32, M CO2 is the molar mass of CO2, M CH4 is the molar mass of CH4, P0 is the standard atmospheric pressure, R is the ideal gas constant, C1 ′ is the rate of change of concentration C1 per unit time, (C2-C1) ′ It is the rate of change of (C2-C1) per unit time.

[0024] In order to better remove water vapor and enrich methane, the pretreatment unit further includes a multi-stage water removal module 71, and the methane enrichment module 62 includes an adsorption and desorption module.

[0025] In order to accurately obtain the gas concentration, further, the first detector 51 and the second detector 52 are NDIR detectors.

[0026] The method for detecting greenhouse gas flux at a water-air interface according to an embodiment of the present invention, that is, the working method of the flux detection device according to this embodiment, is specifically as follows.

[0027] A manned ship (or unmanned ship) carries a detector to collect samples above the water area.

[0028] Air enters the first circulation cell 31 in the first channel, and the first detector 51 obtains the concentration C1 of carbon dioxide in the first circulation cell 31 .

[0029] The air enters the second circulation pool 32 in the second channel, and the air in the second circulation pool 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.

[0030] The gases in the first channel and the second channel are mixed and then sent to a pre-treatment unit to remove water vapor from the mixed gas.

[0031] The second detector 52 obtains the concentration C2 of carbon dioxide in the gas after the water vapor is removed, and the sensor 53 obtains the temperature T and the water vapor pressure e above the water body.

[0032] The calculation module 54 calculates the carbon dioxide flux F1 and the methane flux F2 according to the output values ​​of the detector and the sensor 53 .

[0033] .

[0034] .

[0035] V1 and S1 are the volume and inner surface area of ​​the first flow cell, V2 and S2 are the volume and inner surface area of ​​the second flow cell, M CO2 is the molar mass of CO2, M CH4 is the molar mass of CH4, P0 is the standard atmospheric pressure, R is the ideal gas constant, C1 ′ is the rate of change of concentration C1 per unit time, (C2-C1) ′ It is the rate of change of (C2-C1) per unit time.

[0036] Example 2.

[0037] An application example of the shipborne water-air interface greenhouse gas flux detection device and method according to Example 1 of the present invention.

[0038] In this application example, an unmanned boat is used. The sensor 53 uses a thermometer and a wet-bulb manometer to obtain the temperature T of the detector and the water vapor pressure e above the water body. The first circulation pool 31 and the second circulation pool 32 are the same, S1=S2=10cm 2 , V1=V2=20cm 3 The first detector 51 and the second detector 52 are both NDIR detectors.

[0039] 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.

[0040] The first flow cell 31 , the first valve 41 and the first detector 51 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.

[0041] The second channel is provided with a second circulation pool 32, 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.

[0042] 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 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.

[0043] In the multi-stage dehydration module 71, the first stage 72 adopts the air-cooled dehydration principle. A fan is designed on the surface of the dehydration module. The fan is surrounded by a multi-layer curved aluminum thin-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 dehydration effect. The second stage 73 uses a chemical desiccant, the third stage 74 uses a physical desiccant, and the fourth stage 75 uses a Nafion permeation tube. The multi-stage dehydration 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.

[0044] The second detector 52 obtains the concentration C2 of carbon dioxide in the mixed gas downstream of the first pump 81 by using NDIR technology.

[0045] The calculation module 54 is used to obtain the carbon dioxide flux F1 and the methane flux F2.

[0046] .

[0047] .

[0048] M CO2 is the molar mass of CO2, M CH4 is the molar mass of CH4, P0 is the standard atmospheric pressure, R is the ideal gas constant, C1 ′ is the rate of change of concentration C1 per unit time, (C2-C1) ′ It is the rate of change of (C2-C1) per unit time.

[0049] 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 of the present invention, is specifically as follows.

[0050] The unmanned boat carries a detector to sample in the water body. The thermometer outputs the temperature of the detector in the air as T=303.15 K, and the wet-bulb pressure gauge outputs the water vapor pressure above the water body as e=31.8 hPa.

[0051] The first flow controller 11 is opened, 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 of carbon dioxide C1=420.1 µmol / mol in the first circulation pool 31 is obtained through the first detector 51.

[0052] 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%.

[0053] The second flow controller 12 is opened, and the gas enters the second detector 52, and the concentration of carbon dioxide is obtained as C2 = 422.0 µmol / mol.

[0054] The calculation module obtains the carbon dioxide flux F1 and the methane flux F2.

[0055] .

[0056] .

[0057] M CO2 =44 g / mol,MCH4 =16g / mol.

[0058] Substituting the measured actual value into the above calculation formula, the carbon dioxide flux F1=3.23 μmol m -2 s -1 , F2 = 0.24 μmol m -2 s -1 .

[0059] Example 3.

[0060] According to the application example of the ship-borne water-air interface greenhouse gas flux detection device and method in Example 1 of the present invention, the difference from Example 2 is that: 1. The first flow cell 31 and the second flow cell 32 are different. V1=20cm 3 , V2=30cm 3 , S1=10cm 2 , S2=15cm 2 .

[0061] 2. There is no need to use the first switching module, so that the air enters the first channel and the second channel at the same time after passing through the first flow controller 11.

[0062] 3. Use manned ships.

[0063] 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: A manned ship carrying a detector took samples in the water. The thermometer measured T = 303.15 K, and the wet-bulb pressure gauge output the water vapor pressure above the water body as e = 31.8 hPa.

[0064] The first flow controller 11 is opened, and air passes through the first flow controller 11 and enters the first circulation cell 31 and the second circulation cell 32 at the same time. The first valve 41 is opened, and the concentration of carbon dioxide C1=429.8 µmol / mol in the first circulation cell 31 is obtained through the first detector 51.

[0065] 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%.

[0066] The second flow controller 12 is opened, and the gas enters the second detector 52, and the concentration of carbon dioxide C2 = 431.8 µmol / mol is obtained.

[0067] The calculation module is used to obtain the carbon dioxide flux F1 and the methane flux F2.

[0068] .

[0069] .

[0070] Substituting each parameter into the above formula, we can obtain the carbon dioxide flux F1 = 3.3 μmol m -2 s -1 , methane flux F2 = 0.25 μmol m -2 s -1 .

Claims

1. A ship-borne water-air interface greenhouse gas flux detection device, comprising a ship 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 the 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 a second circulation pool, a carbon dioxide removal module, a methane enrichment module and a 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 sensor that acquires the temperature T and the water vapor pressure e above the body of water; A calculation module, the calculation module is used to calculate the carbon dioxide flux F1 and the methane flux F2 according to the output values ​​of the detector and the sensor; ； ； V1 and S1 are the volume and inner surface area of ​​the first flow cell, V2 and S2 are the volume and inner surface area of ​​the second flow cell, M CO2 is the molar mass of CO2, M CH4 is the molar mass of CH4, P0 is the standard atmospheric pressure, R is the ideal gas constant, C1 ′ is the rate of change of concentration C1 per unit time, (C2-C1) ′ It is the rate of change of (C2-C1) per unit time.

2. The detection device according to claim 1, characterized in that: The water vapor pressure e was obtained using a wet-bulb manometer.

3. The detection device according to claim 1, characterized in that: The 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 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 detection device according to claim 1, characterized in that: The detector is a NDIR detector.

6. A greenhouse gas flux detection method based on the detection device of claim 1, specifically: The ship carries a detector to conduct mobile sampling and testing above the water-air interface; 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 the water vapor is removed, and the sensor obtains the temperature T and the water vapor pressure e above the water body; The calculation module obtains the carbon dioxide flux F1 and the methane flux F2 according to the output values ​​of the detector and the sensor; ； ； V1 and S1 are the volume and inner surface area of ​​the first flow cell, V2 and S2 are the volume and inner surface area of ​​the second flow cell, M CO2 is the molar mass of CO2, M CH4 is the molar mass of CH4, P0 is the standard atmospheric pressure, R is the ideal gas constant, C1 ′ is the rate of change of concentration C1 per unit time, (C2-C1) ′ It is the rate of change of (C2-C1) per unit time.

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