JP2005049279A - Device of measuring global warming gas component in liquid - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device of measuring a global warming gas component in liquid capable of using a liquid containing the global warming gas component as a measuring sample, and having excellent accuracy and rapidity. <P>SOLUTION: In this measuring device 1, a test liquid including, for example, methane is supplied, and methane in the test liquid is extracted continuously into, for example, carbon tetrachloride so as to be equilibrated with the methane concentration in the test liquid, and an infrared ray is transmitted through carbon tetrachloride after methane extraction stored in a cell 5, and the infrared ray is filter-processed and detected by a non-dispersive infrared detector 8. Since the methane-containing quantity in the liquid can be measured by the measuring device 1 in this way, in-situ realtime analysis measurement becomes possible. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an apparatus for measuring a global warming gas component in a liquid that measures a global warming gas component such as methane or carbon dioxide contained in the liquid.

Methane (CH ₄ ) and carbon dioxide (CO ₂ ) are known as gas components that warm the earth due to the greenhouse effect when the content in the atmosphere increases. Methane is produced by the decomposition of organic matter by microorganisms, thermal decomposition of organic matter, etc., and the main sources of release to the atmosphere include wetlands, paddy fields, livestock, gas fields and oil fields. The ocean is also one of the sources of methane emission, since microorganisms in the seabed soil and seawater produce methane in an environment where organic matter is supplied and oxygen supply is scarce. In this ocean, most of the produced methane is consumed in the form of oxidative decomposition in seawater, so it has been conventionally considered not as large as a source of methane emission to the atmosphere.

  However, in recent years, in a low-temperature and high-pressure environment such as the deep sea floor, methane is accumulated in a large amount in the form of an inclusion compound called methane hydrate, in which a part of the methane molecule is solidified by combining with water molecules. It became clear. Methane hydrate binds to water molecules in a low-temperature and high-pressure environment without the methane produced by the decomposition of organic matter by microorganisms present in the seabed soil without being transferred to seawater and consumed. Methane produced by the formation and decomposition of organic matter by microorganisms present in seawater settles on the seabed and is formed by combining with water molecules under a low temperature and high pressure environment.

  In order for methane hydrate to exist in the solid state, the aforementioned low temperature and high pressure environment is required. Therefore, when environmental changes occur, methane hydrate is easily decomposed to transfer methane into seawater. If a large amount of methane hydrate accumulated in the ocean breaks down at one time, it cannot consume all the methane in seawater, but releases a large amount of methane into the atmosphere, which can cause rapid warming. Concerned.

  Methane hydrate has not only negative elements such as warming but also beneficial elements. In other words, methane hydrate can be recovered from the sea floor to the ground, decomposed at an appropriate timing, and vaporized methane to be used as fuel. As mentioned above, methane hydrate is present in large quantities on the ocean floor, so it is considered to be an important energy source in the current situation where fossil fuel depletion is a concern. Therefore, accurately grasping the distribution of methane hydrate in the ocean is an extremely important issue in terms of environmental measures and energy supply measures.

  On the other hand, carbon dioxide is produced in large quantities by combustion of fuel accompanying industrial production activities and emissions accompanying life support activities of animals. Since this carbon dioxide dissolves in water to some extent, in the global carbon dioxide circulation system, rivers, lakes and oceans, especially the ocean, absorb a large amount of carbon dioxide and perform a buffer function against the concentration of carbon dioxide in the atmosphere. . Therefore, accurately grasping the concentration distribution of carbon dioxide in the ocean is an important issue for environmental measures.

  By the way, conventionally, methane in water is purged and trapped with methane gas from the water to extract the methane in water into the gas phase, and gas chromatography using the flame ionization detection method (abbreviated as FID method) for the gas phase methane. (For example, refer nonpatent literature 1). In the FID method, an organic gas is sent together with a carrier gas into a hydrogen flame, a weak current generated by the combustion of the organic gas is detected, and the current change is detected to measure the concentration (for example, Non-patent document 2).

  Carbon dioxide is measured by a non-dispersive infrared spectroscopic device after thoroughly mixing water and air (gas-liquid equilibrator), taking out the air and dehumidifying it (for example, see Non-Patent Document 3).

Kunio Nakajo, Yukichi Yoshino, "New Experimental Chemistry Course 9 Analytical Chemistry II", 2nd edition, Maruzen Co., Ltd., March 1979, p69-70 T. Gamo, J. Ishibashi, H. Sakai, B. Tilbrook, “Methane anomalies in seawater above the Loihi submarine summit area, Hawaii.), Geochimica et Cosmochimica Acta, 51, 1987, p28 57-2864 Edited by the Oceanographic Society of Japan, “The Sea and the Environment-When the Sea Changes, the Earth Changes,” First Print, Kodansha, September 10, 2001, p137-147

  However, the conventional methods that have been used for measuring methane and carbon dioxide have the following problems. The conventional methods that have been used for the above-described measurement of methane and carbon dioxide have a limitation that a liquid cannot be used as a measurement sample, and the measurement sample must be a gas. Therefore, when measuring, for example, methane in the ocean, that is, seawater, the gas component such as methane contained in the seawater is once vaporized and then purged and trapped to extract it into the atmosphere, and the vaporized gas is measured. The method of analyzing as a sample must be taken.

  As described above, in the conventional method, an operation for once vaporizing a liquid sample containing methane is performed, so that it is difficult to vaporize on the seabed under high pressure (about 10 MPa at a depth of 1000 m). For this reason, since it cannot measure in the state as it is with the liquid which is a measuring object originally, for example, seawater, what is called in-situ, it must analyze after collecting a sample.

  Such problems are also problematic in that it is impossible to grasp in real time phenomena such as hot water containing methane due to pyrolysis of organic matter due to volcanic activity on the seabed, and methane seepage due to changes in the seabed ground. In addition, since in-situ measurement is not possible and the methane leached from the methane hydrate in the ocean cannot be continuously measured, the deposition distribution cannot be understood as a wide-area map.

  An object of the present invention is to provide a global warming gas component measuring device in liquid that can use a liquid containing a global warming gas component as a measurement sample and is excellent in accuracy and rapidity.

The present invention provides a test solution supply means for supplying a test solution containing a global warming gas component,
An organic solvent supply means for supplying a non-infrared absorbing organic solvent;
An extraction means for continuously extracting the global warming gas component contained in the test liquid into the non-infrared absorbing organic solvent so as to be in equilibrium with the concentration of the global warming gas component in the test liquid;
A cell formed of a translucent material and containing a non-infrared absorbing organic solvent after extraction of a global warming gas component;
A light source that emits infrared rays toward the cell;
An optical filter for filtering the infrared rays transmitted through the cell and the non-infrared absorbing organic solvent contained in the cell;
A non-dispersive infrared detector for detecting infrared light filtered by an optical filter.

In the invention, it is preferable that the extraction unit includes a gas permeable membrane.
The present invention also provides a test liquid supply means for supplying a test liquid containing a global warming gas component,
An organic solvent supply means for supplying a non-infrared absorbing organic solvent;
A packing material (column) that retains the global warming gas component contained in the test solution and can be eluted by the eluent;
A cell formed of a translucent material and containing a non-infrared absorbing organic solvent after elution of a global warming gas component from the column;
A light source that emits infrared rays toward the cell;
An optical filter for filtering the infrared rays transmitted through the cell and the non-infrared absorbing organic solvent contained in the cell;
A non-dispersive infrared detector for detecting infrared light filtered by an optical filter.

In the present invention, the optical filter is configured to be capable of filtering so as to selectively transmit at least two different wavelengths.
Drive means provided in the optical filter, for driving the optical filter so that the optical filter can selectively transmit infrared rays of two wavelengths different from each other;
A calculation means for calculating an infrared detection output having one wavelength and an infrared detection output having the other wavelength to reduce the influence of one interference component and / or compensate for noise or drift; It is characterized by including.

Further, in the present invention, a plurality of the optical filters are provided so as to selectively transmit at least two different wavelengths.
Switching means provided in the optical filter, for switching the optical filter so that the plurality of optical filters can selectively transmit at least two infrared rays having different wavelengths, respectively;
A calculation means for calculating an infrared detection output having one wavelength and an infrared detection output having the other wavelength to reduce the influence of one interference component and / or compensate for noise or drift; It is characterized by including.

In the present invention, the global warming gas component is methane,
The non-infrared absorbing organic solvent is one selected from carbon tetrachloride, tetrachloroethylene, and carbon disulfide.

In the present invention, the global warming gas component is carbon dioxide,
The non-infrared absorbing organic solvent is carbon disulfide.

  According to the present invention, the apparatus for measuring a global warming gas component in a liquid continuously causes the global warming gas component contained in the test liquid to be in equilibrium with the global warming gas component-containing concentration in the test liquid. By extracting to a non-infrared absorbing organic solvent, transmitting infrared light through the non-infrared absorbing organic solvent, and detecting the transmitted infrared with a non-dispersive infrared detector. Can be measured. Thus, the global warming gas component measuring device in the liquid can measure in-situ without performing operations such as once vaporizing the liquid sample, and can continuously measure the liquid sample. Therefore, it is possible to measure and map the global warming gas components in liquids such as oceans, rivers and lakes in real time.

  Further, according to the present invention, by using a gas permeable membrane as the extraction means, the global warming gas component contained in the test liquid is balanced with the global warming gas component content concentration in the test liquid with a simple configuration. Therefore, it is possible to continuously extract into a non-infrared absorbing organic solvent so that the cost of the apparatus can be reduced and the apparatus can be widely used.

  Further, according to the present invention, the global warming gas component measuring device in the liquid is once held on the column after the global warming gas component contained in the test liquid is once adsorbed to the packing material (also referred to as a column). The non-infrared absorbing organic solvent is eluted from the global warming gas component, the infrared ray is transmitted through the non-infrared absorbing organic solvent, and the transmitted infrared ray is detected by a non-dispersive infrared detector. Thus, the global warming gas component concentration can be measured. By this, the same effect as the above-mentioned global warming gas component measuring device in the liquid can be produced.

  Further, according to the present invention, the global warming gas component measuring device in the liquid detects the infrared rays having two different wavelengths selected by the optical filter, respectively, and detects the infrared detection output having one wavelength and the other. Using the infrared detection output having a wavelength, the calculation means can perform calculation so as to reduce the influence of one interfering component that interferes with the measurement accuracy of methane or compensate for noise or drift. This makes it possible to eliminate the influence of substances other than the measurement target substance mixed in the non-infrared absorbing organic solvent, such as water, on the measurement result, and to compensate for noise and drift. It becomes possible.

  Further, according to the present invention, methane can be extracted into one selected from carbon tetrachloride, tetrachloroethylene, and carbon disulfide, which are non-infrared absorbing organic solvents, and non-dispersive infrared analysis can be performed. It becomes possible to measure methane contained in the liquid in-situ.

  In addition, according to the present invention, carbon dioxide can be extracted into carbon disulfide, which is a non-infrared absorbing organic solvent, and non-dispersive infrared analysis can be performed. Therefore, carbon dioxide contained in the liquid is in-situ. It becomes possible to measure with.

  FIG. 1 is a system diagram showing a simplified configuration of a measurement device 1 for measuring a global warming gas component in liquid according to an embodiment of the present invention. A global warming gas component measuring device 1 in liquid (hereinafter simply referred to as measuring device 1) includes a test liquid supply means 2 for supplying a test liquid containing a global warming gas component, and a non-infrared absorbing organic solvent. The organic warming gas component contained in the test liquid and the non-infrared absorbing organic solvent so that the concentration of the global warming gas component contained in the test liquid is balanced. Extraction means 4 for continuous extraction, a cell 5 formed of a translucent material and containing a non-infrared absorbing organic solvent after extraction of a global warming gas component, and a light source 6 for emitting infrared rays toward the cell An optical filter 7 that filters the infrared rays that have passed through the cell 5 and the non-infrared absorbing organic solvent contained in the cell 5, and a non-dispersive infrared detector 8 that detects the infrared rays filtered by the optical filter 7. And non-dispersive infrared detector 8 It includes an amplifier 9 is an amplifier for amplifying the detected output signal I, a processing circuit 10 connected to the amplifier 9, and a display unit 11 for displaying the detected output.

In the present embodiment, a case where methane (CH ₄ ), which is one of the global warming gas components, is measured is illustrated.

  The test liquid supply means 2 includes a pump that collects a liquid containing methane such as seawater, a storage tank that temporarily stores the collected test liquid, and a liquid feed pump that supplies the test liquid in the storage tank to the extraction means 4. It is comprised. Further, the test liquid supply means 2 may be composed of only a pump that collects a liquid containing methane.

The organic solvent supply means 3 is an organic material selected from carbon tetrachloride (CCl ₄ ), tetrachloroethylene (Cl ₂ C═CCl ₂ ), and carbon disulfide (CS ₂ ), which are non-infrared absorbing organic solvents. An organic solvent supply source 12 having a storage tank for storing the solvent, a liquid feed pump 13 for feeding the non-infrared absorbing organic solvent stored in the organic solvent supply source 12 to the extraction means 4, and the organic solvent supply source 12 And a first pipe 14 that connects the liquid feed pump 13 and the extraction means 4 to form a transport path for the non-infrared absorbing organic solvent.

In the present specification, the non-infrared absorbing organic solvent is an organic having almost no infrared absorption property in the same wavelength range as the infrared absorption wavelength of methane as a measurement target substance and carbon dioxide (CO ₂ ) described later. It means a solvent.

  FIG. 2 is a cross-sectional view showing a simplified configuration of an example of the extraction unit 4. The extraction means 4 shown as an example in FIG. 2 is an apparatus called a liquid-liquid equilibrator or a continuous solvent extractor. The liquid-liquid equilibrator that is the extraction means 4 has a substantially double-pipe structure. The outer tube 21 is made of stainless steel or hard synthetic resin. A gas permeable membrane made of amorphous fluoropolymer or porous polytetrafluoroethylene is used for the inner tube 22. The gas permeable membrane constituting the inner tube 22 is a porous membrane in which a large number of extremely fine holes 25 are formed, and does not allow liquid to permeate, but allows gas components contained in the liquid to permeate. It is a film that can be used. A first space 23 is formed between the inner wall of the outer tube 21 and the outer wall of the inner tube 22. A second space 24 is formed inside the inner tube 22. The first space 23 and the second space 24 are separated from each other with the inner tube 22 as a partition wall and are not in direct communication.

  The outer tube 21 has a first supply port 26 for supplying the test solution from the test solution supply means 2 to the first space 23 in the direction of arrow 30, and the test solution flowing in the first space 23 in the direction of arrow 31. The first discharge port 27 for discharging to the second space 24, the second supply port 28 for supplying the non-infrared absorbing organic solvent to the second space 24 from the organic solvent supply means 3 in the direction of the arrow 32, and the flow through the second space 24. A second discharge port 29 is formed to discharge the passed non-infrared absorbing organic solvent in the direction of arrow 33, that is, to be sent to the cell 5.

  The test solution supplied from the first supply port 26 and discharged from the first discharge port 27, and the non-infrared absorbing organic solvent supplied from the second supply port 28 and discharged from the second discharge port 29 are: It flows through each space in a state of contact through the inner tube 22. As described above, the inner tube 22 is composed of a gas permeable film that does not transmit liquid but allows only gas components in the liquid to pass. Therefore, the test solution and the non-infrared absorbing organic solvent pass through each space. During the flow, methane contained in the test solution is extracted into the non-infrared absorbing organic solvent that has passed through the inner tube 22 and has flowed through the second space 24.

  The concentration of methane extracted into the non-infrared absorbing organic solvent reaches equilibrium with the methane concentration contained in the test solution while flowing from upstream to downstream in the direction indicated by arrows 32 and 33. . That is, in the cell 5 which is an analytical sample storage container, a non-infrared absorbing organic solvent containing methane having the same concentration as the methane concentration contained in the test solution is connected to the tube connecting the extraction means 4 and the cell 5. It is supplied through the second pipe 34 which is a path.

  As the light source 6, a known light source capable of emitting infrared rays can be used. The wavelength of infrared rays emitted from the light source 6 is, for example, 0.76 to 60 μm. However, the upper and lower limits of the emission infrared wavelength are not particularly strictly defined, and may be in different ranges.

  The optical filter 7 is a band-pass filter that transmits only infrared rays in a specific wavelength range. When measuring methane, the optical filter 7 selectively transmits a band around a wavelength of 3.32 μm, which is the infrared absorption wavelength of methane. Used.

  A known one can be used for the non-dispersive infrared detector 8. The processing circuit 10 is realized by, for example, a microcomputer equipped with a central processing unit (abbreviated as CPU). The processing circuit 10 includes a memory (not shown). Absorbance information of a reference sample containing methane at various concentrations, a so-called calibration curve, is stored in advance in the memory, and the non-dispersed red input via the amplifier 9 is stored. Based on the detection output from the external detector 8 and the information read from the memory, the analytical measurement result of methane is obtained and output to the display means 11 together with the image display control signal.

  The display means 11 is an image display device including a liquid crystal or a cathode ray tube, for example, and displays a detection signal detected by the non-dispersive infrared detector 8 and amplified by the amplifier 9, that is, an analysis measurement result of methane. The display unit 11 preferably includes a recording device such as a printer or an XY plotter.

  Hereinafter, the operation of the measuring apparatus 1 will be described. First, the test liquid supply means 2 collects, for example, seawater containing methane in the vicinity of the sea bottom as a test liquid, and supplies it from the first supply port 26 to the liquid-liquid equilibrator that is the extraction means 4. On the other hand, from the organic solvent supply means 3, for example, carbon tetrachloride stored in the organic solvent supply source 12 is supplied from the second supply port 28 to the liquid-liquid equilibrator 4. By flowing through the second space 24 of the liquid-liquid equilibrator 4, methane is extracted from the seawater, and the carbon tetrachloride that has reached a concentration that balances with the methane concentration contained in the seawater is supplied to the second outlet 29. To cell 5.

  Infrared light from the light source 6 is transmitted so as to transmit the carbon tetrachloride in the cell 5 and the carbon tetrachloride in the cell 5 in a state in which the carbon tetrachloride having reached a concentration balanced with the methane concentration contained in the sea water is accommodated in the cell 5. Is emitted. Infrared light that has passed through carbon tetrachloride, which is an analytical measurement sample, is selectively transmitted only through the band around 3.32 μm, which is the infrared absorption wavelength of methane, when passing through the optical filter 7.

  FIG. 3 is a diagram showing an infrared absorption spectrum by FTIR. In FIG. 3, in order to confirm the infrared absorption wavelength of methane and carbon tetrachloride, the result of having calculated | required the infrared absorption spectrum by the Fourier-transform infrared spectrophotometer (FTIR) is shown. A line 35 in FIG. 3 is an infrared absorption spectrum of carbon tetrachloride containing methane, a line 36 is an infrared absorption spectrum of only methane gas, and a line 37 is an infrared absorption spectrum of only carbon tetrachloride. is there.

  As seen in the line 36 showing the infrared absorption spectrum of methane only, methane has an infrared absorption characteristic specific to a wavelength of 3.32 μm. On the other hand, as seen in the line 37 showing the infrared absorption spectrum of only carbon tetrachloride, carbon tetrachloride has almost no infrared absorption characteristic in the band near 3.32 μm which is the infrared absorption wavelength of methane. . Thus, carbon tetrachloride, tetrachloroethylene, and carbon disulfide have almost no infrared absorption characteristics in the vicinity of the infrared absorption wavelength of methane, and thus are defined as non-infrared absorbing organic solvents as described above. Therefore, the infrared absorption spectrum shape of carbon tetrachloride containing methane is obtained as the sum of the infrared absorption spectrum of methane and the infrared absorption spectrum of carbon tetrachloride, as seen in line 35 in FIG. .

  As described above, carbon tetrachloride has almost no infrared absorption characteristics near the wavelength of 3.32 μm. Therefore, the change in the infrared intensity at the wavelength of 3.32 μm transmitted through the carbon tetrachloride containing methane is the same as the methane content. Based on differences. Accordingly, when only the band around 3.32 μm, which is the infrared absorption wavelength of methane, is selectively transmitted by the optical filter 7 and the transmitted infrared light is measured by the non-dispersive infrared detector 8, the infrared detection is performed. The change in intensity (absorbance by the analytical measurement sample in the cell 5) can be measured as the concentration of methane contained in carbon tetrachloride, that is, the concentration of methane contained in seawater.

  The detection output from the non-dispersive infrared detector 8 is amplified by the amplifier 9 and sent to the processing circuit 10. The processing circuit 10 obtains the methane concentration based on the calibration curve read from the memory, and outputs it to the display means 11 together with the image display control signal of the obtained result. In the display means 11, the methane concentration in the seawater as a measurement result is displayed in the form of a graph or a table, and a series of measurement operations is completed.

  Although the measuring apparatus according to the second embodiment of the present invention is used for measuring carbon dioxide in a liquid, the overall configuration is the same as that of the first embodiment, and therefore only different points are listed below. The drawings and detailed description are omitted.

  As the test liquid, a liquid sample containing carbon dioxide instead of methane is used. As the non-infrared absorbing organic solvent, carbon disulfide having almost no infrared absorption property is used in the vicinity of 15 μm which is the infrared absorption wavelength of carbon dioxide. As the optical filter 7, an optical filter that selectively transmits a band around a wavelength of 15 μm is used. The non-dispersive infrared detector 8 is an infrared detector having an infrared detection ability near a wavelength of 15 μm. A calibration curve relating to carbon dioxide is stored in advance in the memory of the processing circuit 10.

  The carbon dioxide measuring operation by the measuring device of the second embodiment is executed in the same manner as the methane measurement in the measuring device 1 of the first embodiment.

  FIG. 4 is a system diagram schematically showing the configuration of the measuring apparatus 41 according to the third embodiment of the present invention. The measurement apparatus 41 of the present embodiment is similar to the measurement apparatus 1 of the first embodiment, and corresponding portions are denoted by the same reference numerals and description thereof is omitted.

  The measuring apparatus 41 of the present embodiment is configured such that the optical filter 42 provided is capable of filtering so as to selectively transmit at least two different wavelengths, and is provided in the optical filter 42. The optical filter 42 is at least Driving means 43 for driving the optical filter 42 so that infrared rays having two different wavelengths can be selectively transmitted, an infrared detection output having one wavelength, and an infrared detection output having the other wavelength And calculating means 44 for calculating so as to reduce the influence of one interfering component that interferes with the measurement accuracy of methane and compensate for noise or drift.

  FIG. 5 is a diagram illustrating a configuration of the optical filter 42 that can selectively transmit infrared rays having two different wavelengths. FIG. 5 shows an optical filter 42 in which the inclination angle of the filter disposed on the infrared path 51 with respect to the infrared path 51 is variable. The optical filter 42 shown in FIG. 5 is an optical filter 42 formed so that the wavelength to be transmitted differs according to the incident angle of infrared rays. The driving means 43 includes a motor 52 and a gear box 54 that is a reduction mechanism to which the output shaft 53 of the motor 52 is connected. The output shaft 54 a of the gear box 54 is provided in a direction orthogonal to the infrared path 51. The output shaft 54 a is connected to the side surface of the optical filter 42. Accordingly, the driving force of the motor 52 is transmitted to the optical filter 42, and the optical filter 42 can be angularly displaced reversibly in the direction of the arrow 56. Accordingly, the optical filter 42 can selectively transmit infrared rays having different wavelengths by changing the inclination angle with respect to the infrared path 51. The measuring device 41 also includes a power source for supplying power to the motor 52 of the driving unit 43 and a controller for controlling the operation thereof, but the illustration thereof is omitted.

  FIG. 6 is a diagram illustrating two different wavelengths of infrared rays that are selectively transmitted using the optical filter 42 having the configuration shown in FIG. FIG. 6 is a result of obtaining an infrared absorption spectrum by FTIR by setting the inclination angle of the optical filter 42 having the configuration shown in FIG. 5 with respect to the infrared path 51 to zero (0) degree and plus / minus (±) 45 degrees. Indicates. In FIG. 6, a line 57 indicated by a solid line is an infrared absorption spectrum at an inclination angle of 0 degrees, a line 58 indicated by a one-dot chain line is an infrared absorption spectrum at an inclination angle of 45 degrees, and a line 59 indicated by a broken line is It is an infrared absorption spectrum at an inclination angle of −45 degrees. In the measurement whose result is shown in FIG. 6, since the infrared absorbing object is not interposed on the infrared path 51, the infrared intensity of the wavelength transmitted through the optical filter 42 set at each inclination angle is infrared. Obtained as an absorption spectrum.

  As shown in FIG. 6, the optical filter 42 shown in FIG. 5 selectively transmits infrared light having a wavelength of 3.32 μm at an inclination angle of 0 °, and tilts it to + 45 ° or −45 °, thereby making infrared light having a wavelength of 3.10 μm. Is configured to be selectively transparent.

  The wavelength of 3.10 μm is a wavelength at which water has infrared absorption characteristics. Moreover, water has an infrared absorption characteristic with an absorption coefficient equivalent to that of a wavelength of 3.10 μm at the same wavelength of 3.32 μm as methane. Therefore, by selectively transmitting infrared rays having two wavelengths of 3.32 μm and 3.10 μm and measuring infrared detection outputs (absorbance: abbreviated ABS) at both wavelengths, methane as a measurement target sample is extracted. Even when carbon chloride is mixed with water, it is possible to eliminate the influence of this water on the analytical measurement of methane.

FIG. 7 is a diagram showing absorbance detected at two different wavelengths (λ ₀ , λ ₁ ). With reference to FIG. 7, a method for eliminating the influence of water on the analytical measurement of methane will be described.

Here, one wavelength of 3.32 μm is λ ₁ , and the other wavelength of 3.10 μm is λ ₀ . The absorption coefficient of methane at _one wavelength λ ₁ is εMλ ₁ , the absorption coefficient of water is εWλ ₁ , the absorption coefficient of methane at the other wavelength λ ₀ is εMλ _0, and the absorption coefficient of water is εWλ ₀ . The density | concentration of the methane contained in the carbon tetrachloride which is a measurement sample is set to CM, and the density | concentration of the mixing water contained in the carbon tetrachloride which is a measurement sample is set to CW.

At this time, the infrared intensity of _one wavelength λ ₁ detected by the non-dispersive infrared detector 8, that is, ABS _{λ 1} is given by equation (1). The infrared intensity of the other wavelength lambda ₀ which is detected by the non-dispersive infrared detector 8, i.e. ABS _.lambda.0 is given by equation (2).
ABS _λ1 = εMλ ₁ · CM + εWλ ₁ · CW (1)
ABS _λ0 = εMλ ₀ · CM + εWλ ₀ · CW (2)

At the other wavelength λ ₀ = 3.10 μm, water has infrared absorption characteristics, but methane does not have infrared absorption characteristics, so its absorption coefficient εMλ ₀ is zero. Also, as described above, the other wavelength λ ₀ = 3.10 μm is selected as the wavelength having the same absorption coefficient as that of water at one wavelength λ ₀ = 3.32 μm, so that λ ₁ and λ The absorption coefficient of water at ₀ is equal, and εWλ ₁ = εWλ ₀ .

Therefore, subtracting ABS _λ0 , which is the infrared detection output having the other wavelength λ ₀ , from ABS _λ1, which is the infrared detection output having _one wavelength λ ₁ , that is, subtracting formula (2) from formula (1). Thus, it becomes possible to obtain a highly accurate measurement result of methane by eliminating the influence of water, which is one disturbing component that disturbs the measurement accuracy of methane. This calculation is executed by the calculation means 44 described above.

  As described above, this embodiment exemplifies removing the influence of water mixed in carbon tetrachloride containing methane as a measurement sample. However, the detection outputs related to two different wavelengths are obtained respectively, and both detection outputs are obtained. It is possible to compensate for noise or drift by providing a configuration for calculating the difference between the two.

  FIG. 8 is a system diagram showing a simplified configuration of the measurement apparatus 61 according to the fourth embodiment of the present invention. The measuring device 61 of the present embodiment is similar to the measuring device 41 of the third embodiment, and corresponding portions are denoted by the same reference numerals and description thereof is omitted.

FIG. 9 is a diagram illustrating a configuration of the optical filter 62 provided in the measurement device 61.
It should be noted in the measuring apparatus 61 that the optical filter 62 is provided with two first and second filters 46 and 47 so that two different wavelengths can be selectively transmitted, By providing a switching means 63 for switching between the first filter 46 and the second filter 47 so that the first and second filters 46 and 47 can selectively transmit at least two infrared rays having different wavelengths, respectively. is there.

  The optical filter 62 includes a circular substrate 45 made of a material capable of shielding infrared rays, a first filter 46 that selectively transmits a band around 3.32 μm that is an infrared absorption wavelength of methane, And a second filter 47 that selectively transmits a band in the vicinity of 3.10 μm that is an infrared absorption wavelength. In the substrate 45, circular first and second openings 49 and 50 are formed at positions equidistant from the center 48 of the substrate 45 so as to have respective centers. First and second filters 46 and 47 are attached to the first and second openings 49 and 50, respectively. When the substrate 45 is rotated around its center 48, the centers of the first and second openings 49, 50, that is, the centers of the first and second filters 46, 47 are positioned on the infrared path 51, and An optical filter 62 is provided so as to be able to pass through the first filter 46 and the second filter 47, respectively.

  The switching means 63 is configured similarly to the driving means 43 of the third embodiment described above, but is arranged so that the output shaft 54a of the gear box 54 is parallel to the direction in which the infrared path 51 extends, and the output Since the shaft 54 a is connected to the center 48 of the substrate 45 described above, the rotational driving force of the motor 52 is transmitted to the optical filter 62, and the optical filter 62 is reversibly moved in any direction as indicated by an arrow 55. Can rotate. As a result, the optical filter 62 can selectively switch infrared rays having two different wavelengths by alternately switching filters on the infrared path 51, and the measurement according to the third embodiment described above. The same effect as the device 41 can be obtained.

  FIG. 10 is a system diagram showing a simplified configuration of the measuring apparatus 65 according to the fifth embodiment of the present invention. The measuring device 65 of the present embodiment is similar to the measuring device 1 of the first embodiment, and corresponding portions are denoted by the same reference numerals and description thereof is omitted.

  The measuring device 65 of the present embodiment has a dehumidifying means 66 for removing moisture in the non-infrared absorbing organic solvent in the second pipe line 34 connecting the liquid-liquid equilibrator 4 and the cell 5 as extraction means. In addition, an organic solvent circulation pipe 67 is provided, which is a pipe for refluxing the non-infrared absorbing organic solvent after measurement of methane discharged from the cell 5 to the liquid feeding pump 13.

  The dehumidifying means 66 may be a dehumidifying material such as sodium sulfate, calcium chloride, magnesium sulfate, or molecular sieves, or may be a semipermeable membrane dehumidifier such as a hollow fiber membrane dryer. It may be a polymer having an octadecyl group or an ion exchange group used for lithography, a column based on silica gel, carbon or the like.

  By providing the organic solvent circulation pipe 67 in the measuring device 65, the non-infrared absorbing organic solvent can be reused without being discarded. Further, when the efficiency of the extraction means 4 for continuously extracting methane from the test solution is lowered, the efficiency can be increased by providing the organic solvent circulation pipe 67.

  In addition, in the measuring apparatus 65 of this Embodiment and the measuring apparatus of the 1st-4th Embodiment mentioned above, without providing the outer tube | pipe 21 of the liquid-liquid equilibrator 4 which is an extraction means, the liquid-liquid equilibrator 4 is equipped. The inner tube 22 may be in direct contact with the test solution, and the global warming gas component in the test solution may be extracted into a non-infrared absorbing organic solvent that flows through the inner tube 22. Various modifications are also included in the scope of the present invention.

  FIG. 11 is a system diagram schematically showing the configuration of the measuring apparatus 71 according to the sixth embodiment of the present invention. The measuring apparatus 71 of the present embodiment is similar to the measuring apparatus 1 of the first embodiment, and corresponding portions are denoted by the same reference numerals and description thereof is omitted.

  The measuring device 71 according to the present embodiment includes a branching unit 72 provided between the liquid feed pump 13 and the liquid-liquid equilibrator 4 in the first pipe line 14, that is, on the entry side of the liquid-liquid equilibrator 4, and the second pipe. And a flow path switching valve 73 provided on the outlet side of the liquid-liquid equilibrator 4 in the passage 34, so that the non-infrared absorbing organic solvent does not flow through the liquid-liquid equilibrator 4 from the organic solvent supply means 3. A branch line 74 that can be directly fed to the cell 5 is formed.

  The branching means 72 may be a simple T-shaped tube or may be constituted by another flow path switching valve. By operating the flow path switching valve 73 and switching the flow path of the non-infrared absorbing organic solvent, measurement of the non-infrared absorbing organic solvent that has passed through the liquid-liquid equilibrator 4 and extracted methane from the test solution; Measurement of a so-called blank non-infrared absorbing organic solvent in which methane is not extracted without passing through the liquid-liquid equilibrator 4 can be performed alternately. Thus, since the measurement of the methane content in the target test solution and the measurement of the blank sample with a methane content of zero (0) can be performed alternately, the light source 6 and the non-dispersive infrared detection It is possible to compensate for noise or drift of the device 8.

  FIG. 12 is a system diagram schematically showing the configuration of the measuring apparatus 75 according to the seventh embodiment of the present invention. The measuring apparatus 75 of the present embodiment is substantially similar to the measuring apparatus 1 of the first embodiment, and corresponding portions are denoted by the same reference numerals and description thereof is omitted.

  The measurement device 75 of the present embodiment is configured to be able to sink in the deep sea of, for example, 1000 m or more and measure methane contained in seawater in-situ. In the measuring device 75, the light source 6, the optical filter 7, the non-dispersive infrared detector 8, the amplifier 9, the processing circuit 10, and the recording means 76 for recording the measurement result of methane (the display means 11 of the first embodiment are also provided. However, the light is emitted from the light source 6 through the first optical fiber 78 and is incident on the measurement cell 5. The light transmitted through the non-infrared absorbing organic solvent is guided by the second optical fiber 79 and is incident on the optical filter 7.

  Further, the liquid feed pump 13 of the organic solvent supply means 3 provided in the measuring device 75 and another liquid feed pump 80 for supplying the test liquid to the liquid-liquid equilibrator 4 are stored in, for example, a metal pressure vessel 81. It is immersed in the oil 82 and accommodated in the pressurized container 81. The liquid-liquid equilibrator 4, the cell 5, and the pipe line are accommodated in a tub or casing that directly touches seawater as a test liquid. According to the measuring apparatus 75 configured as described above, the apparatus can be submerged in the deep sea having a depth of 1000 m or more as described above, and the methane content in the seawater can be measured in-situ.

  FIG. 13 is a system diagram schematically showing the configuration of the measuring apparatus 85 according to the eighth embodiment of the present invention. The measuring device 85 of the present embodiment is similar to the measuring device 1 of the first embodiment, and corresponding portions are denoted by the same reference numerals and description thereof is omitted.

  The measuring device 85 includes a test liquid supply pipe 86 that is a pipe for supplying a test liquid from the test liquid supply means 2, and a pipe for supplying a non-infrared absorbing organic solvent used as an eluent in the present embodiment. For example, methane, which is a global warming gas component contained in the test liquid, is provided downstream of the first flow path switching valve 87 for switching the flow path to the first pipe line 14 and the liquid feed pump 13. And a column 88 that can be eluted by the eluent, a pipe that is provided on the outlet side of the column 88 and that discharges the liquid from the column 88 to the cell 5 and a pipe that discharges the liquid out of the system. A second flow path switching valve 89 for switching the flow path is provided.

  The column 88 is, for example, a column or a capillary column based on a polymer having an octadecyl group or an ion exchange group used in liquid chromatography, silica gel, carbon, or the like. When the test liquid containing methane is supplied to the column 88, the column 88 adsorbs and holds methane in the test liquid on the column 88, and the flow path is switched by the first flow path switching valve 87, so that the test liquid becomes the test liquid. Instead, when the non-infrared absorbing organic solvent as the eluent is supplied to the column 88, methane can be eluted by the eluent.

  In this measuring device 85, first, the flow path of the first flow path switching valve 87 is switched to the test liquid supply means 2 side, and the test liquid containing methane is sent to the column 88 by the liquid feed pump 13, and the methane is supplied to the column. Adsorb to 88. The test liquid after methane is adsorbed in the column 88 is discharged out of the system by switching the flow path of the second flow path switching valve 89 to the external discharge flow path side.

  After a certain amount of test solution is fed and methane is adsorbed to the column 88, the first flow path switching valve 87 is switched to the organic solvent supply source 12 side, and the non-infrared absorbing organic solvent as the eluent is removed. The liquid is fed to the column 88 by the liquid feed pump 13. The non-infrared absorbing organic solvent eluting methane in the column 88 is supplied to the cell 5 by switching the flow path of the second flow path switching valve 89 to the supply flow path side to the cell 5. The non-infrared absorbing organic solvent eluting methane passes through the cell 5, and at this time, the methane concentration is quantified by measuring the infrared absorption.

(Example)
Examples of the present invention will be described below. Carbon tetrachloride containing no methane and a sample solution in which methane having a concentration of 0 to 80 μmol / L is dissolved are prepared and contained in carbon tetrachloride using the measuring device 41 according to the third embodiment of the present invention. Methane was analyzed and measured to verify its accuracy.

FIG. 14 is a diagram illustrating the methane content measurement result. As shown in FIG. 14, the measurement result of the methane content by the measuring device 41 of the present invention shows an extremely high first-order correlation of the true value of the methane content and the correlation coefficient R ² = 0.9958, which is highly accurate. It can be seen that the methane content can be measured.

It is a systematic diagram which simplifies and shows the structure of the global warming gas component measuring apparatus 1 in the liquid which is one Embodiment of this invention. It is sectional drawing which simplifies and shows a structure about an example of the extraction means. It is a figure which shows the infrared absorption spectrum by FTIR. It is a systematic diagram which simplifies and shows the structure of the measuring apparatus 41 which is the 3rd Embodiment of this invention. It is a figure which illustrates the structure of the optical filter 42 which can selectively permeate | transmit infrared rays of two different wavelengths. It is a figure which illustrates the infrared rays of two different wavelengths selectively permeate | transmitted using the optical filter of the structure shown in FIG. It is a figure which shows the light absorbency detected in two different wavelengths ((lambda) ₀ , (lambda) ₁ ). It is a systematic diagram which simplifies and shows the structure of the measuring apparatus 61 which is the 4th Embodiment of this invention. It is a figure which shows the structure of the optical filter 62 with which the measuring apparatus 61 is equipped. It is a systematic diagram which simplifies and shows the structure of the measuring apparatus 65 which is the 5th Embodiment of this invention. It is a systematic diagram which simplifies and shows the structure of the measuring apparatus 71 which is the 6th Embodiment of this invention. It is a systematic diagram which simplifies and shows the structure of the measuring apparatus 75 which is the 7th Embodiment of this invention. It is a systematic diagram which simplifies and shows the structure of the measuring apparatus 85 which is the 8th Embodiment of this invention. It is a figure showing a methane content measurement result.

Explanation of symbols

1, 41, 61, 65, 71, 75, 85 Global warming gas component measuring device in liquid 2 Test liquid supply means 3 Organic solvent supply means 4 Extraction means 5 Cell 6 Light source 7, 42, 62 Optical filter 8 Non-dispersion Infrared detector 9 Amplifier 10 Processing circuit 11 Display means 12 Organic solvent supply source 13, 80 Liquid feed pump 43 Drive means 44 Calculation means 63 Switching means 66 Dehumidifying means 67 Organic solvent circulation pipe 72 Branch means 73, 87, 89 Flow Path switching valve 74 Branch pipe 76 Recording means 77 Pressure-resistant container 78 First optical fiber 79 Second optical fiber 81 Pressurized container 82 Oil

Claims (7)

A test solution supply means for supplying a test solution containing a global warming gas component;
An organic solvent supply means for supplying a non-infrared absorbing organic solvent;
An extraction means for continuously extracting the global warming gas component contained in the test liquid into the non-infrared absorbing organic solvent so as to be in equilibrium with the concentration of the global warming gas component in the test liquid;
A cell formed of a translucent material and containing a non-infrared absorbing organic solvent after extraction of a global warming gas component;
A light source that emits infrared rays toward the cell;
An optical filter for filtering the infrared rays transmitted through the cell and the non-infrared absorbing organic solvent contained in the cell;
An apparatus for measuring a global warming gas component in liquid, comprising: a non-dispersive infrared detector that detects infrared light filtered by an optical filter.   The said extraction means contains a gas permeable film, The global warming gas component measuring apparatus in a liquid of Claim 1 characterized by the above-mentioned. A test solution supply means for supplying a test solution containing a global warming gas component;
An organic solvent supply means for supplying a non-infrared absorbing organic solvent;
A packing material (column) that retains the global warming gas component contained in the test solution and can be eluted by the eluent;
A cell formed of a translucent material and containing a non-infrared absorbing organic solvent after elution of a global warming gas component from the column;
A light source that emits infrared rays toward the cell;
An optical filter for filtering the infrared rays transmitted through the cell and the non-infrared absorbing organic solvent contained in the cell;
An apparatus for measuring a global warming gas component in a liquid, comprising: a non-dispersive infrared detector that detects infrared light filtered by an optical filter. The optical filter is configured to be filterable so as to selectively transmit at least two different wavelengths.
Drive means provided in the optical filter, for driving the optical filter so that the optical filter can selectively transmit infrared rays of two wavelengths different from each other;
A calculation means for calculating an infrared detection output having one wavelength and an infrared detection output having the other wavelength to reduce the influence of one interference component and / or compensate for noise or drift; The global warming gas component measuring apparatus in the liquid according to any one of claims 1 to 3, comprising: A plurality of the optical filters are provided so as to selectively transmit at least two different wavelengths.
Switching means provided in the optical filter, for switching the optical filter so that the plurality of optical filters can selectively transmit at least two infrared rays having different wavelengths, respectively;
A calculation means for calculating an infrared detection output having one wavelength and an infrared detection output having the other wavelength to reduce the influence of one interference component and / or compensate for noise or drift; The global warming gas component measuring apparatus in the liquid according to any one of claims 1 to 3, comprising: The global warming gas component is methane,
The global warming gas component measurement according to claim 1, wherein the non-infrared absorbing organic solvent is one selected from carbon tetrachloride, tetrachloroethylene, and carbon disulfide. apparatus. The global warming gas component is carbon dioxide,
The said non-infrared absorptive organic solvent is carbon disulfide, The global warming gas component measuring apparatus in the liquid in any one of Claims 1-5 characterized by the above-mentioned.

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