Underway system and method for measuring concentration of trace greenhouse gas in water body or atmosphere

Abstract

The invention discloses a sailing system and method for measuring the concentration of trace greenhouse gas in a water body or atmosphere, and relates to the technical field of gas concentration measurement, the sailing system comprises a water-gas balancer, an off-axis integral cavity output spectrum measuring instrument, a standard gas sample introduction assembly and an atmosphere sample introduction assembly, the upper end of the water-gas balancer is communicated with a water inlet pipe, and the lower end of the water-gas balancer is provided with an overflow pipe; a gas inlet pipe of the water-gas balancer is communicated with a gas outlet of the off-axis integral cavity output spectrum measuring instrument, the off-axis integral cavity output spectrum measuring instrument is respectively communicated with a gas outlet pipe of the water-gas balancer, the standard gas sampling assembly and the atmosphere sampling assembly through valves and pipelines, a water inlet pipe is communicated with a water area to be measured, and the atmosphere sampling assembly is communicated with an atmosphere area to be measured. The trace greenhouse gas difficult to measure in a water liquid phase is transferred into a gas phase through a headspace equilibrium method by utilizing the water-gas balancer, and the concentration of the trace greenhouse gas in the water or the atmosphere is accurately and continuously measured by utilizing an off-axis integral cavity output spectrum technology.

Description

Technical Field

[0001] The present invention relates to the technical field of gas concentration measurement, and in particular to a cruise system and method for measuring the concentration of trace greenhouse gases in water or the atmosphere. Background Art

[0002] Greenhouse gases play a vital role in the Earth system and are closely related to climate change. These gases capture heat in the atmosphere and affect the radiative forcing of the Earth-atmosphere system. Taking carbon monoxide as an example, as an indirect greenhouse gas, it is also a key component of the global carbon cycle. By reacting with hydroxyl radicals in the atmosphere, it increases the lifetime of other climate-related greenhouse gases (methane, carbon dioxide, etc.), thereby affecting the oxidation capacity of the Earth's atmosphere and climate change. In addition, it is also involved in the tropospheric ozone cycle and the formation of nitrate aerosols. It is estimated that the emission of 100Tg CO is equivalent to the emission of 5Tg methane. Therefore, it is of great significance to detect the concentration of greenhouse gases in water bodies, including the atmosphere.

[0003] Traditional greenhouse gas concentration detection technologies can be divided into optical and non-optical methods. The most commonly used method for analyzing trace gases in water bodies (or atmosphere) is gas chromatography. Its advantage is high measurement sensitivity, but its disadvantage is that it requires sample preparation and a long measurement time, and it is impossible to complete real-time online precise monitoring and cruise analysis of greenhouse gases in water bodies (or atmosphere). In addition, there is currently no independently developed cruise measurement device for greenhouse gases in water bodies (or atmosphere) in China. Therefore, it is of great research value to realize high-precision cruise monitoring and analysis technology and system for trace greenhouse gases in water bodies (or atmosphere), improve the country's independent establishment of a complete greenhouse gas observation network, and accurately assess the "dual carbon" issue.

[0004] In summary, the current prior art lacks a measuring device that can be used for cruise detection of trace greenhouse gas concentrations in water bodies (or the atmosphere). Summary of the invention

[0005] The purpose of the present invention is to provide a cruise system and method for measuring the concentration of trace greenhouse gases in water bodies or the atmosphere, so as to solve the problems existing in the above-mentioned prior art and enable real-time online accurate monitoring and cruise analysis of the concentration of trace greenhouse gases in water bodies or the atmosphere.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] The present invention provides a cruise system for measuring the concentration of trace greenhouse gases in water bodies or the atmosphere, comprising a water vapor balance, an off-axis integrating cavity output spectrum measuring instrument, a standard gas injection assembly and an atmosphere injection assembly, wherein the upper end of the water vapor balance is connected to a water inlet pipe, and the lower end is provided with an overflow pipe, the air inlet pipe of the water vapor balance is connected to the air outlet of the off-axis integrating cavity output spectrum measuring instrument, the off-axis integrating cavity output spectrum measuring instrument is connected to the air outlet pipe of the water vapor balance, the standard gas injection assembly and the atmosphere injection assembly through valves and pipelines, the water inlet pipe is connected to a water area to be measured, and the atmosphere injection assembly is connected to an atmospheric area to be measured.

[0008] Preferably, the outlet pipe of the water vapor balancer and the outlet pipe of the atmospheric sampling assembly are both provided with a drying filter assembly and a flow valve, the absorption cell of the off-axis integrating cavity output spectrum measuring instrument is provided with a temperature sensor and a pressure sensor, and the flow valve and the pressure sensor are both communicatively connected to a control unit.

[0009] Preferably, the drying and filtering assembly comprises a dehydration assembly and a gas filter which are arranged in sequence, the dehydration assembly is used to prevent vapor or liquid from entering the off-axis integrating cavity output spectrum measuring instrument from the system, and the gas filter is used to remove interfering gases in the sample gas to be measured.

[0010] Preferably, the water removal component is a cold trap, and the gas filter is a carbon dioxide absorber; the outlet pipe of the water vapor balancer and the outlet pipe of the atmosphere injection component are connected to the three-way solenoid valve on the air inlet of the off-axis integrating cavity output spectrum measuring instrument through a three-way solenoid valve, a drying tube is arranged between the two three-way solenoid valves, and the other end of the three-way solenoid valve on the air inlet of the off-axis integrating cavity output spectrum measuring instrument is connected to the standard gas injection component.

[0011] Preferably, the atmosphere sampling assembly comprises an air pump with a flow rate of 0.35 L / min, one end of the air pump is connected to the external atmosphere, and the other end is connected to the air inlet of the off-axis integrating cavity output spectrum measuring instrument.

[0012] Preferably, the standard gas injection assembly includes four air inlet pipes, each of which is provided with a solenoid valve and is respectively connected to a gas source of two standard gases of different concentrations, a synthetic air and a nitrogen gas.

[0013] Preferably, the water-gas balancer comprises an outer balancer shell, an inner balancer shell, a water distribution plate and a top cover, the water distribution plate is clamped on the inner side of the top of the outer balancer shell, and the top cover is sealed and clamped on the outer side, a number of water leakage holes are evenly distributed on the water distribution plate, a baffle plate which can manually close the water leakage holes in the outer circle of the connecting cavity is provided below the water distribution plate, a water distribution cavity is formed between the top cover and the water distribution plate, a water inlet pipe is provided on the top cover, the inner balancer shell is hung on the water distribution plate, the upper end of the inner balancer shell is open and located in a connecting cavity, and the lower end of the connecting cavity is open and suspended Inverted on the lower end of the outer balancer shell, the bottom of the outer balancer shell protrudes inwardly to provide an overflow pipe, the top of the connecting cavity is provided with a connecting pipe, the connecting pipe is suspended in the inner balancer shell, the top of the connecting cavity is connected to the bottom of the water distribution plate through a flow cavity, the connecting cavity and the flow cavity are both provided with ventilation pipes connected to the outside atmosphere, the flow cavity is also provided with an air intake pipe, the outer balancer shell is provided with an exhaust pipe, the ventilation pipe, the air intake pipe and the exhaust pipe all pass through the water distribution plate and the top cover.

[0014] Preferably, the exhaust pipe is connected to an air pump with a flow rate of 0.24L / min, and the air pump is connected to the air inlet of the off-axis integrating cavity output spectrum measuring instrument; the water inlet pipe is connected to a water inlet pump with a flow rate of 2L / min, the diameter of the overflow pipe is the same as the diameter of the flow cavity and is 10cm, the top of the overflow pipe is 25cm higher than the bottom of the outer balancer shell, the diameter of the inlet pipe and the exhaust pipe is 2-5cm, and the volume ratio of the inner balancer to the outer balancer is 1:40.

[0015] Preferably, the off-axis integrating cavity output spectrum measuring instrument comprises a laser generator, a beam splitter, a photodetector, an absorption cell and a focusing lens. The laser generator and the beam splitter are sequentially arranged at one end of the absorption cell, and the focusing lens and a photodetector are sequentially arranged at the other end. The reflectivity of the two reflectors in the absorption cell is 99.5%. The beam splitter divides the laser emitted by the laser generator into two beams, one of which enters the absorption cell and the other passes through a laser standard mirror to hit another photodetector. Both of the two photodetectors are communicatively connected to a control unit. An air inlet and an air outlet with valves are arranged on the absorption cell; the air outlet of the absorption cell can be connected to the outside atmosphere and the water vapor balancer respectively through a three-way solenoid valve; the central wavelength emitted by the laser generator is 2330nm.

[0016] The present invention discloses a method for measuring the concentration of trace greenhouse gases in water or the atmosphere. Based on the above-mentioned cruise system for measuring the concentration of trace greenhouse gases in water or the atmosphere, the method specifically comprises the following steps:

[0017] S1, according to the test requirements, at least one of the standard gas, synthetic air and nitrogen or a certain proportion thereof is introduced into the absorption cell of the off-axis integrating cavity output spectrum measuring instrument and fills the entire absorption cell, and a concentration reference value is obtained by performing analog-to-digital conversion on the data detected by the photoelectric detector of the off-axis integrating cavity output spectrum measuring instrument.

[0018] S2, according to the test requirements, use a three-way solenoid valve to select the use of a water vapor balance to measure the concentration of trace greenhouse gases in the water body, or choose to use an atmospheric sampling assembly to measure the concentration of trace greenhouse gases in the atmosphere; if you choose to use a water vapor balance to measure the concentration of trace greenhouse gases in the water body, turn on the water inlet pump on the water inlet pipe of the water vapor balance and the air pump on the air outlet pipe, and the water sample drips into the outer balancer shell and the inner balancer shell through the water distribution plate, and the air pump continuously extracts the gas to be tested in the outer balancer shell and passes through the cold trap, gas filter and drying tube in turn into the air inlet of the off-axis integrating cavity output spectrum measuring instrument; if you choose to use the atmospheric sampling assembly to measure the concentration of trace greenhouse gases in the atmosphere, you need to turn on the air pump of the atmospheric sampling assembly to allow the sample to be tested to pass through the cold trap, gas filter and drying tube in turn into the air inlet of the off-axis integrating cavity output spectrum measuring instrument;

[0019] S3, the pre-treated sample is measured and converted into analog-to-digital by the off-axis integrating cavity output spectrum measuring instrument, and demodulated and gas concentration inverted by an algorithm, and finally the concentration value of the sample is obtained. By maintaining the set air intake speed, the concentration value of the sample can be continuously and real-time measured during the navigation process.

[0020] Compared with the prior art, the present invention has achieved the following technical effects:

[0021] The present invention utilizes a water vapor balance to transfer trace greenhouse gases that are difficult to measure in the liquid phase of water into the gas phase through the headspace balance method, and then utilizes off-axis integrating cavity output spectroscopy technology with non-contact, fast response, and strong anti-interference optical detection to achieve accurate and continuous measurement of the concentration of trace greenhouse gases in water or the atmosphere. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0023] Figure 1 It is a schematic diagram of the structure of a cruise system for measuring the concentration of trace greenhouse gases in water or the atmosphere in an embodiment of the present invention;

[0024] Figure 2 This is a schematic diagram of the structure of a water-gas balancer in an embodiment of the present invention;

[0025] Figure 3 Schematic diagram of the structure of an off-axis integrating cavity output spectrum measuring instrument in an embodiment of the present invention;

[0026] In the figure: 1-water-gas balancer, 2-off-axis integrating cavity output spectrum measuring instrument, 3-standard gas injection assembly, 4-atmospheric injection assembly, 5-three-way solenoid valve, 6-cold trap, 7-gas filter, 8-flow valve, 9-water inlet pipe, 10-vent pipe, 11-exhaust pipe, 12-inlet pipe, 13-outer balancer shell, 14-flow cavity, 15-connecting cavity, 16-inner balancer shell, 17-overflow pipe, 18-water distribution cavity, 19-laser generator, 20-beam splitter, 21-laser standard mirror, 22-absorption cell, 23-air inlet, 24-temperature sensor, 25-pressure sensor, 26-air outlet, 27-focusing lens, 28-photoelectric detector, 29-control unit. DETAILED DESCRIPTION

[0027] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] The purpose of the present invention is to provide a cruise system and method for measuring the concentration of trace greenhouse gases in water bodies or the atmosphere, so as to solve the problems existing in the prior art and enable real-time online accurate monitoring and cruise analysis of the concentration of trace greenhouse gases in water bodies or the atmosphere.

[0029] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0030] Embodiment 1

[0031] like Figures 1 to 3As shown, in this embodiment, a navigation system for measuring the concentration of trace greenhouse gases in water bodies or the atmosphere is provided, which includes a water vapor balance 1, an off-axis integrating cavity output spectrum measuring instrument 2, a standard gas injection assembly 3 and an atmosphere injection assembly 4. The upper end of the water vapor balance 1 is connected to a water inlet pipe 9, and an overflow pipe 17 is provided at the lower end. The air inlet pipe 12 of the water vapor balance 1 is connected to an air outlet 26 of the off-axis integrating cavity output spectrum measuring instrument 2. The off-axis integrating cavity output spectrum measuring instrument 2 is connected to the air outlet pipe of the water vapor balance 1, the standard gas injection assembly 3 and the atmosphere injection assembly 4 through valves and pipelines, respectively. The water inlet pipe 9 is connected to the water area to be measured, and the atmosphere injection assembly 4 is connected to the atmospheric area to be measured.

[0032] As an optional solution, in this embodiment, the outlet pipe of the water vapor balancer 1 and the outlet pipe of the atmospheric sampling assembly 4 are both provided with a drying filter assembly and a flow valve 8, and the absorption pool 22 of the off-axis integrating cavity output spectrum measuring instrument 2 is provided with a temperature sensor 24 and a pressure sensor 25, and the flow valve 8 and the pressure sensor 25 are both connected to a control unit 29 for communication. The temperature sensor 24 and the pressure sensor 25 can accurately reflect the temperature and pressure in the absorption pool 22, and the control unit 29 can adjust the flow valve 8 according to the data feedback of the pressure sensor 25, thereby maintaining a relatively stable air pressure in the absorption pool 22 to reduce its influence on the measurement result. The pressure value of the integrating chamber of this device under normal working conditions is about 105mbar.

[0033] As an optional solution, the drying and filtering component in this embodiment includes a dehydration component and a gas filter 7 arranged in sequence. The dehydration component is used to prevent vapor or liquid from entering the off-axis integrating cavity output spectrum measuring instrument 2 from the system, and the gas filter 7 is used to remove interfering gases in the sample gas.

[0034] As an optional solution, the water removal component in this embodiment is a cold trap 6, which can condense most of the water vapor in the air at the top of the water vapor balance 1, and the gas filter 7 is a carbon dioxide absorber to eliminate the influence of the carbon dioxide absorption spectrum; the outlet pipe of the water vapor balance 1 and the outlet pipe of the atmospheric sampling component 4 are connected to the three-way solenoid valve 5 on the air inlet 23 of the off-axis integrating cavity output spectrum measuring instrument 2 through a three-way solenoid valve 5, and a Nafion drying tube is arranged between the two three-way solenoid valves 5 to further remove trace water vapor in the gas to be measured; the other end of the three-way solenoid valve 5 on the air inlet 23 of the off-axis integrating cavity output spectrum measuring instrument 2 is connected to the standard gas sampling component 3.

[0035] As an optional solution, the atmosphere sampling assembly 4 in this embodiment includes an air pump with a flow rate of 0.35 L / min, one end of the air pump is connected to the external atmosphere, and the other end is connected to the air inlet 23 of the off-axis integrating cavity output spectrum measuring instrument 2.

[0036] As an optional solution, the standard gas injection assembly 3 in this embodiment includes four air inlet pipes 12, each of which is provided with a solenoid valve and is respectively connected to two air sources of standard gas with different concentrations, one synthetic air and one nitrogen gas.

[0037] As an optional solution, the water-gas balancer 1 in this embodiment includes an outer balancer shell 13, an inner balancer shell 16, a water distribution plate and a top cover. The top inner side of the outer balancer shell 13 is clamped with a water distribution plate, and the outer side is sealed with a top cover. A number of water leakage holes are evenly distributed on the water distribution plate. A baffle that can manually close the water leakage holes in the outer circle of the connecting cavity 15 is provided under the water distribution plate. A baffle structure similar to a shutter can be selected. A water distribution cavity 18 is provided between the top cover and the water distribution plate. A water inlet pipe 9 is provided (connected) on the top cover. The inner balancer shell 16 is hung on the water distribution plate. The upper end of the inner balancer shell 16 is open and located in a connecting cavity 15. The lower end of the connecting cavity 15 is open and suspended upside down on the lower end of the outer balancer shell 13. An overflow pipe 17 is protruding inward from the bottom of the outer balancer shell 13. After the water fills the balancer, the overflowing water sample is discharged to the external area through the overflow pipe 17. The top of the connecting cavity 15 A connecting pipe is provided in the inner balancer shell 16, and the connecting pipe is suspended in the inner balancer shell 16. The top of the connecting cavity 15 is connected (connected) with the bottom of the water distribution plate through a flow cavity 14. The connecting cavity 15 and the flow cavity 14 are both provided with a vent pipe 10 connected to the outside atmosphere to ensure smooth liquid inflow. The flow cavity 14 is also provided with an air inlet pipe 12. The head space balance gas sample enters the off-axis integrating cavity through the exhaust pipe 11 and returns to the balance chamber after the output spectrum measurement, forming an air circuit closed loop to reduce the balance time of the device. When the continuous measurement results are relatively stable, it is necessary to manually close the baffle under the water distribution plate so that the water sample enters the auxiliary balance chamber only through the connecting cavity 15, which not only reduces the influence of external air, but also ensures that the air pressure in the main balancer is the same as the external atmospheric pressure. An exhaust pipe 11 is provided in the outer balancer shell 13, and the vent pipe 10, the air inlet pipe 12 and the exhaust pipe 11 all pass through the water distribution plate and the top cover. The outer balancer housing 13 and the inner balancer housing 16 are preferably made of transparent acrylic material to facilitate viewing of the internal state of the balancer.

[0038] As an optional solution, in this embodiment, an air pump with a flow rate of 0.24L / min is connected to the exhaust pipe 11, and the air pump is connected to the air inlet 23 of the off-axis integrating cavity output spectrum measuring instrument 2; the front end of the water inlet pipe 9 is connected to the water inlet pump with a flow rate of 2L / min, the diameter of the overflow pipe 17 is the same as the diameter of the flow chamber 14, and is preferably 10cm, the top of the overflow pipe 17 is at least 5cm higher than the bottom of the outer balancer shell 13, the diameter of the air inlet pipe 12 and the exhaust pipe 11 is 2-5cm, the top of the overflow pipe 17 is 25cm higher than the bottom of the outer balancer shell 13, the diameter of the ventilation pipe 10 is 1-2cm, the capacity of the outer balancer shell 13 is at least 7L, the head space after the internal water filling is 3L-5L, and the capacity of the inner balancer shell 16 is 100mL. In this embodiment, the diameter of the connecting pipe is preferably 15 cm, the top of the overflow pipe 17 is 25 cm higher than the bottom of the outer balancer shell 13, and the volume ratio of the inner balancer to the outer balancer is preferably 1:40.

[0039] As an optional solution, the off-axis integrating cavity output spectrum measuring instrument 2 in this embodiment includes a laser generator 19, a beam splitter 20, a photodetector 28, an absorption cell 22 and a focusing lens 27. The laser generator 19 and the beam splitter 20 are arranged in sequence at one end of the absorption cell 22, and a focusing lens 27 and a photodetector 28 are arranged in sequence at the other end. The reflectivity of the two reflectors in the absorption cell 22 is 99.5%. The beam splitter 20 divides the laser emitted by the laser generator 19 into two beams, one of which enters the absorption cell 22 and the other passes through the laser standard mirror 21 to hit the other photodetector 28. Both photodetectors 28 are communicatively connected to the control unit 29. The absorption cell 22 is provided with an air inlet 23 and an air outlet 26 with a valve; the air outlet 26 of the absorption cell 22 can be connected to the external atmosphere and the water vapor balancer 1 respectively through a three-way solenoid valve 5; the central wavelength of the laser emitted by the laser generator 19 is 2330nm. The sample to be measured is measured and converted into analog-to-digital by the off-axis integrating cavity output spectrum measuring instrument 2, and demodulated and gas concentration inverted by an algorithm, and finally the concentration value of the gas to be measured is obtained.

[0040] Embodiment 2

[0041] like Figure 1 As shown, this embodiment discloses a method for measuring the concentration of trace greenhouse gases in water or the atmosphere, based on the cruise system for measuring the concentration of trace greenhouse gases in water or the atmosphere in the above embodiment 1, specifically comprising the following steps:

[0042] S1, according to the test requirements, at least one of the two standard gases, synthetic air and nitrogen or a certain proportion thereof is configured to enter the absorption cell 22 of the off-axis integrating cavity output spectrum measuring instrument 2 and fill the entire absorption cell 22, and a concentration reference value is obtained by performing analog-to-digital conversion on the data detected by the photoelectric detector 28 of the off-axis integrating cavity output spectrum measuring instrument 2. Among them, the two standard gases and nitrogen with different concentrations can be configured with concentration gradient gas samples, and the device is calibrated by measuring the background value determined by synthetic air, and nitrogen alone can also be used to flush the gas pipeline.

[0043] S2, according to the test requirements, use the three-way solenoid valve 5 to select the use of the water vapor balance 1 to measure the concentration of trace greenhouse gases in the water body, or select the use of the atmospheric sampling assembly 4 to measure the concentration of trace greenhouse gases in the atmosphere; if the water vapor balance 1 is selected to measure the concentration of trace greenhouse gases in the water body, the water inlet pump on the water inlet pipe 9 of the water vapor balance 1 and the air pump on the air outlet pipe are turned on, and the water flows through the water distribution plate and drips into the outer balancer shell 13 and the inner balancer shell 16, and the air pump continuously extracts the gas to be tested in the outer balancer shell 13 and passes through the cold trap 6, the gas filter 7 and the drying tube in turn into the air inlet 23 of the off-axis integrating cavity output spectrum measuring instrument 2; if the atmospheric sampling assembly 4 is selected to measure the concentration of trace greenhouse gases in the atmosphere, it is necessary to open the air pump of the atmospheric sampling assembly 4 so that the atmospheric sample passes through the cold trap 6, the gas filter 7 and the drying tube in turn into the air inlet 23 of the off-axis integrating cavity output spectrum measuring instrument 2;

[0044] S3, the pre-treated sample is measured and converted into analog-to-digital by the off-axis integrating cavity output spectrum measuring instrument 2, and demodulated and gas concentration inverted by the algorithm, and finally the concentration value of the gas to be measured is obtained. If the gas to be measured maintains the set intake speed, the concentration value of the gas to be measured can be continuously and real-time measured during the navigation process.

[0045] Among them, trace greenhouse gases can be gases such as carbon monoxide and methane. The following takes the measurement of carbon monoxide concentration as an example to deduce its concentration calculation process. Specifically, the balance gas in the upper headspace of the water vapor balance device 1 follows the first-order kinetic equation, and its balance process can be described by the following equation:

[0046]

[0047] Where P gas P is the equilibrium gas concentration of the gas to be tested discharged from the outlet pipe of the water-gas balancer 1 at the recorded time t. water is the concentration of the gas to be tested in the water sample, To balance the equilibrium gas concentration of the gas to be measured in the room, τ can be calculated based on the slope of the change in trace greenhouse gas concentration over time.

[0048] Under the setting of the control unit 29, the laser emitted by the laser transmitter is divided into two beams by the beam splitter 20. One part is hit by a photodetector 28 through the Etalon laser standard mirror 21, and the other beam leaves the absorption cell 22 through the light exit hole after multiple reflections in the absorption cell 22, and hits another photodetector 28 through the focusing lens 27. The two photodetectors 28 are converted to digital by the analog-to-digital converter in the high-performance workstation unit, and demodulated and inverted by the algorithm. The temperature sensor 24 and the pressure sensor 25 accurately reflect the temperature and pressure in the cavity, and the control system is used to reduce the influence of pressure changes on the measurement results;

[0049] The high-performance workstation unit 11 calculates the spectrum measurement result α according to the Lambert-Beer law:

[0050]

[0051] Where d is the cavity length, R is the reflectivity of the cavity mirror, I0 is the incident laser intensity, I t is the intensity of transmitted light. The concentration m of the greenhouse gas component to be measured in the equilibrium gas is obtained by the integral area of ​​the absorption spectrum, and then the greenhouse gas concentration data in the water body is inverted by the following formula:

[0052]

[0053] Where P g is atmospheric pressure, P w is the saturated vapor pressure under known temperature and salinity conditions during measurement, β is the Benson solubility coefficient of greenhouse gases, T k is the Kelvin temperature. The concentration m of carbon monoxide in the atmospheric sample is obtained by the integral area of ​​the absorption spectrum.

[0054] The cruise system for measuring the carbon monoxide concentration in water or the atmosphere in this embodiment is based on the off-axis integrating cavity output spectral technology and a water-gas balancer 1 with dual balance chambers, wherein the water-gas balancer 1 can transfer the carbon monoxide in the liquid phase of the water body, which is difficult to measure, to the gas phase for measurement. The system has a simple structure, is applicable to water bodies with different turbidities, and has little biological fouling. It can be applied to the determination of various dissolved gases in water bodies, including but not limited to carbon monoxide and methane. The off-axis integrating cavity output spectral technology has the advantages of non-contact, fast response speed, and strong anti-interference optical detection. It also has the advantages of low optical interference noise, shortened optical path adjustment time, and simple structure, and can accurately and continuously measure the concentration of the gas to be measured in the water body or the atmosphere.

[0055] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the method and core ideas of the present invention. At the same time, for those skilled in the art, according to the ideas of the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A cruise system for measuring the concentration of trace greenhouse gases in water or atmosphere, characterized by: It includes a water vapor balance, an off-axis integrating cavity output spectrum measuring instrument, a standard gas injection assembly and an atmosphere injection assembly. The upper end of the water vapor balance is connected to a water inlet pipe, and the lower end is provided with an overflow pipe. The air inlet pipe of the water vapor balance is connected to the air outlet of the off-axis integrating cavity output spectrum measuring instrument. The off-axis integrating cavity output spectrum measuring instrument is connected to the air outlet pipe of the water vapor balance, the standard gas injection assembly and the atmosphere injection assembly through valves and pipelines respectively. The water inlet pipe is connected to the water area to be measured, and the atmosphere injection assembly is connected to the atmospheric area to be measured.

2. The cruise system for measuring the concentration of trace greenhouse gases in water or atmosphere according to claim 1, characterized in that: The outlet pipe of the water vapor balancer and the outlet pipe of the atmosphere sampling assembly are both provided with a drying filter assembly and a flow valve, the absorption cell of the off-axis integrating cavity output spectrum measuring instrument is provided with a temperature sensor and a pressure sensor, and the flow valve and the pressure sensor are both communicatively connected to a control unit.

3. The cruise system for measuring the concentration of trace greenhouse gases in water or atmosphere according to claim 1, characterized in that: The drying and filtering component comprises a dehydration component and a gas filter which are arranged in sequence. The dehydration component is used to prevent steam or liquid from entering the off-axis integrating cavity output spectrum measuring instrument, and the gas filter is used to remove interfering gas in the sample gas to be measured.

4. The cruise system for measuring the concentration of trace greenhouse gases in water or atmosphere according to claim 3, characterized in that: The dehydration component is a cold trap, and the gas filter is a carbon dioxide absorber; the outlet pipe of the water vapor balancer and the outlet pipe of the atmosphere injection component are connected to the three-way solenoid valve on the air inlet of the off-axis integrating cavity output spectrum measuring instrument through a three-way solenoid valve, and the other end of the three-way solenoid valve on the air inlet of the off-axis integrating cavity output spectrum measuring instrument is connected to the standard gas injection component; a drying tube is arranged between the two three-way solenoid valves.

5. The cruise system for measuring the concentration of trace greenhouse gases in water or atmosphere according to claim 1, characterized in that: The atmospheric sampling assembly comprises an air pump with a flow rate of 0.35 L / min, one end of the air pump is connected to the external atmosphere, and the other end is connected to the air inlet of the off-axis integrating cavity output spectrum measuring instrument.

6. The cruise system for measuring the concentration of trace greenhouse gases in water or atmosphere according to claim 1, characterized in that: The standard gas injection assembly comprises four air inlet pipes, each of which is provided with a solenoid valve and is respectively connected to two air sources of standard gas with different concentrations, a synthetic air and a nitrogen gas.

7. The cruise system for measuring the concentration of trace greenhouse gases in water or atmosphere according to claim 1, characterized in that: The water-gas balancer comprises an outer balancer shell, an inner balancer shell, a water distribution plate and a top cover. The water distribution plate is clamped on the inner side of the top of the outer balancer shell, and the top cover is sealed and clamped on the outer side. A number of water leakage holes are evenly distributed on the water distribution plate. A baffle that can manually close the water leakage holes in the outer circle of the connecting cavity is provided below the water distribution plate. A water distribution cavity is between the top cover and the water distribution plate. A water inlet pipe is provided on the top cover. The inner balancer shell is hung on the water distribution plate. The upper end of the inner balancer shell is open and located in a connecting cavity. The lower end of the connecting cavity is open and suspended upside down. At the lower end of the outer balancer shell, an overflow pipe is protruding inward from the bottom of the outer balancer shell, and a connecting pipe is arranged on the top of the connecting cavity. The connecting pipe is suspended in the inner balancer shell, and the top of the connecting cavity is connected to the bottom of the water distribution plate through a flow cavity. The connecting cavity and the flow cavity are both provided with ventilation pipes connected to the outside atmosphere, and the flow cavity is also provided with an intake pipe. An exhaust pipe is arranged in the outer balancer shell, and the ventilation pipe, the intake pipe and the exhaust pipe all pass through the water distribution plate and the top cover.

8. The cruise system for measuring the concentration of trace greenhouse gases in water or atmosphere according to claim 7, characterized in that: The exhaust pipe is connected to an air pump with a flow rate of 0.24L / min, and the air pump is connected to the air inlet of the off-axis integrating cavity output spectrum measuring instrument; the water inlet pipe is connected to a water inlet pump with a flow rate of 2L / min, the diameter of the overflow pipe is the same as the diameter of the flow cavity and is 10cm, the top of the overflow pipe is 25cm higher than the bottom of the outer balancer shell, the diameters of the inlet pipe and the exhaust pipe are 2-5cm, and the volume ratio of the inner balancer to the outer balancer is 1:

40.

9. The cruise system for measuring the concentration of trace greenhouse gases in water or atmosphere according to claim 1, characterized in that: The off-axis integrating cavity output spectrum measuring instrument comprises a laser generator, a beam splitter, a photodetector, an absorption cell and a focusing lens. The laser generator and the beam splitter are arranged in sequence at one end of the absorption cell, and the focusing lens and a photodetector are arranged in sequence at the other end. The reflectivity of two reflectors in the absorption cell is 99.5%. The beam splitter splits the laser emitted by the laser generator into two beams, one of which enters the absorption cell and the other passes through a laser standard mirror and hits another photodetector. Both of the two photodetectors are connected to a control unit for communication. An air inlet and an air outlet with valves are arranged on the absorption cell; the air outlet of the absorption cell can be connected to the outside atmosphere and the water vapor balancer respectively through a three-way electromagnetic valve; the central wavelength of the laser emitted by the laser generator is 2330nm.

10. A method for measuring the concentration of trace greenhouse gases in water or the atmosphere, based on the cruise system for measuring the concentration of trace greenhouse gases in water or the atmosphere according to any one of claims 1 to 9, characterized in that: The specific steps include: S1, according to the test requirements, at least one of the standard gas, synthetic air and nitrogen or a certain proportion thereof is introduced into the absorption cell of the off-axis integrating cavity output spectrum measuring instrument and fills the entire absorption cell, and the concentration gradient reference value is obtained by performing analog-to-digital conversion on the data detected by the photoelectric detector of the off-axis integrating cavity output spectrum measuring instrument. S2, according to the test requirements, use a three-way solenoid valve to select the use of a water vapor balance to measure the concentration of trace greenhouse gases in the water body, or choose to use an atmospheric sampling assembly to measure the concentration of trace greenhouse gases in the atmosphere; if you choose to use a water vapor balance to measure the concentration of trace greenhouse gases in the water body, turn on the water inlet pump on the water inlet pipe of the water vapor balance and the air pump on the air outlet pipe, and the water sample drips into the outer balancer shell and the inner balancer shell through the water distribution plate, and the air pump continuously extracts the gas to be tested in the outer balancer shell and passes through the cold trap, gas filter and drying tube in turn into the air inlet of the off-axis integrating cavity output spectrum measuring instrument; if you choose to use the atmospheric sampling assembly to measure the concentration of trace greenhouse gases in the atmosphere, you need to turn on the air pump of the atmospheric sampling assembly to allow the sample to be tested to pass through the cold trap, gas filter and drying tube in turn into the air inlet of the off-axis integrating cavity output spectrum measuring instrument; S3, the pre-treated sample is measured and converted into analog-to-digital by the off-axis integrating cavity output spectrum measuring instrument, and demodulated and gas concentration inverted by an algorithm, and finally the concentration value of the sample is obtained. By maintaining the set air intake speed, the concentration value of the sample can be continuously and real-time measured during the navigation process.

Images