Gas Measuring Instruments

Abstract

To provide a gas measurement device which offers improved accuracy in detecting a target gas in the atmosphere.SOLUTION: A gas measurement device is provided, comprising a filter for removing miscellaneous gases from a sample gas of the atmosphere, and a gas sensor for detecting a target gas from the sample gas passing through the filter, the miscellaneous gases being at least one selected from nitrogen gas, oxygen gas, and noble gases.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to gas measuring instruments. [Background technology]

[0002] Patent Document 1 discloses a gas measuring instrument that includes a dehumidification cell that dehumidifies a sample gas and removes ethanol from the sample gas, a concentration cell that concentrates a target gas in the dehumidified sample gas by adsorbing and desorbing the target gas, and a MEMS gas sensor that detects the concentrated target gas. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-041833 A Summary of the Invention [Problem to be solved by the invention]

[0004] The gas measuring instrument described in Patent Document 1 cannot remove nitrogen gas, oxygen gas, and rare gases, which are the main gases other than water vapor in the atmosphere. Therefore, there is a risk that it will not be possible to detect a trace amount of a target gas contained in the atmosphere. The present disclosure provides a gas measuring instrument that can improve the detection accuracy of a target gas in the atmosphere. [Means for solving the problem]

[0005] A gas measuring instrument according to one aspect of the present disclosure includes a filter for removing interference gases from a sample gas in the atmosphere, and a gas sensor for detecting a target gas from the sample gas that has passed through the filter. The interference gas is at least one gas selected from the group consisting of nitrogen gas, oxygen gas, and rare gases.

[0006] According to this gas measuring instrument, nitrogen gas, oxygen gas or rare gas is removed from the sample gas in the atmosphere by the filter, and the target gas is detected from the sample gas by the gas sensor. In this way, the main component gas in the atmosphere is removed by the filter, so that the target gas is relatively concentrated. Therefore, this gas measuring instrument can improve the detection accuracy of the target gas in the atmosphere.

[0007] In one embodiment, the filter may be a porous metal complex in which metal ions and organic ligands are bonded. Compared to general adsorption members, porous metal complexes are less likely to be electrically active and can remove low molecular weight gases. By using the porous metal complex as a filter, the gas measuring instrument can appropriately remove nitrogen gas, oxygen gas, and rare gases.

[0008] In one embodiment, the filter may include a breathable bag containing the powdered porous metal complex. In this case, the gas measuring instrument can adjust the amount and the containing form of the porous metal complex according to the flow rate or the shape of the flow path of the passing sample gas, and can reduce the risk of the powdered porous metal complex diffusing into the measurement system or the atmosphere.

[0009] In one embodiment, the filter has a container that contains the powdered porous metal complex, and the container may include an inlet for introducing a sample gas and an outlet for exhausting the sample gas. In this case, the gas measuring instrument can reduce the risk of the powdered porous metal complex diffusing into the measurement system or the atmosphere.

[0010] In one embodiment, the filter may include a first filter made of a porous metal complex that mainly removes oxygen gas, and a second filter made of a porous metal complex that is disposed downstream of the first filter and mainly removes nitrogen gas and rare gases. With this configuration, when filter replacement is required for maintenance, for example, an operator does not need to replace the entire filter, but can replace only the filter that requires maintenance. This improves maintainability of the gas measuring instrument.

[0011] In one embodiment, the first filter may be made of a porous metal complex in which a metal ion is bonded to tetracyanoquinodimethane, and the second filter may be made of a porous metal complex in which a metal ion is bonded to terephthalic acid or methylene. By employing relatively low molecular weight tetracyanoquinodimethane and relatively low molecular weight terephthalic acid or methylene as ligands, the gas measuring device can reduce the gaps in the porous metal complex. Therefore, the gas measuring device can selectively take in only low molecular weight gas from the sample gas. Effect of the Invention

[0012] According to the gas measuring instrument according to the present disclosure, the detection accuracy of the target gas in the atmosphere can be improved. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a schematic diagram illustrating an example of a gas measuring instrument according to an embodiment. [Diagram 2] FIG. 13 is a schematic diagram showing a modified example of the gas measuring instrument according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. In the following description, the same or equivalent elements are given the same reference numerals, and redundant description will not be repeated. The dimensional ratios of the drawings do not necessarily match those in the description. The terms "upper", "lower", "left" and "right" are based on the illustrated state and are for convenience.

[0015] [Gas measuring device configuration] FIG. 1 is a schematic diagram showing an example of a gas measuring instrument according to an embodiment. The gas measuring instrument 1 shown in FIG. 1 is a device for detecting a target gas from a sample gas 100. The sample gas 100 is a gas in the atmosphere, and mainly contains nitrogen (N 2 ) gas, oxygen (O 2The sample gas 100 includes at least one gas selected from the group consisting of water vapor, hydrogen (H 2 ) gas. The sample gas 100 may be obtained from a closed space.

[0016] As shown in FIG. 1, the gas measuring instrument 1 includes a gas sensor 2. The gas sensor 2 may be any gas sensor such as a semiconductor type, an electrochemical type, or a quartz crystal type. The gas sensor 2 is configured to be capable of detecting a target gas contained in a sample gas 100. As an example of the target gas, acetic acid (CH 3 COOH), but is not limited to this.

[0017] The gas sensor 2 is housed inside a chamber 3. The chamber 3 is connected to a vacuum pump 5 via an exhaust pipe 4, and the internal space is depressurized. An intake pipe 6 is connected to the chamber 3. When the internal space of the chamber 3 is depressurized by the vacuum pump 5, a sample gas 100 is drawn from the intake pipe 6 into the internal space of the chamber 3. The gas sensor 2 detects a target gas from the sample gas 100 drawn into the internal space of the chamber 3.

[0018] A filter 7 is disposed upstream of the gas sensor 2, here inside the intake pipe 6. The filter 7 removes interference gases from the sample gas 100. The filter 7 may remove interference gases from the sample gas 100 without adsorbing the target gas. The interference gases are gases other than the target gas. The interference gases include nitrogen (N 2 ) gas, oxygen (O 2 ) gas and at least one gas selected from rare gases.

[0019] The filter 7 includes a first filter 8 and a second filter 9. The first filter 8 includes a bag 8a having air permeability. The bag 8a is made of a nonwoven fabric, for example. The shape of the bag 8a can be adjusted so as to be in close contact with the inner wall of the intake pipe 6. The bag 8a accommodates a powdery porous metal complex 8b inside. The porous metal complex 8b is a compound in which a metal ion is bonded to an organic ligand. The porous metal complex 8b is a metal organic framework (MOF) or a porous coordination polymer (PCP). The porous metal complex 8b may be zeolite or porous silica. The porous metal complex 8b mainly removes oxygen gas and water vapor, for example. Such a porous metal complex 8b is, for example, a porous metal complex in which a metal ion is bonded to tetracyanoquinodimethane (TCNQ). The metal ion may be selected from a variety of ions that are coordinatively unsaturated.

[0020] The second filter 9 is disposed downstream of the first filter 8. The second filter 9 has a bag body 9a having air permeability. The bag body 9a is, for example, made of a nonwoven fabric. The shape of the bag body 9a can be adjusted so as to adhere closely to the inner wall of the intake pipe 6. The bag body 9a accommodates a powdery porous metal complex 9b inside. The porous metal complex 9b is a compound in which a metal ion and an organic ligand are bonded. The porous metal complex 9b is a metal-organic framework or a porous coordination polymer. The porous metal complex 9b mainly removes nitrogen gas and rare gases, for example. Such a porous metal complex 9b is, for example, a porous metal complex in which a metal ion is bonded to terephthalic acid or methylene. The metal ion may be selected from a type of ion that is coordinatively unsaturated. The intake pipe 6 may be made of a soft tube. In this case, the first filter 8 and the second filter 9 can be easily arranged and removed.

[0021] A partition member 10 may be provided between the chamber 3 and the filter 7. The partition member 10 is, for example, a member disposed at the connection port between the chamber 3 and the intake pipe 6, and having an inner diameter smaller than the inner diameter of the intake pipe 6. By providing the partition member 10, the filter 7 is prevented from being pushed into the chamber 3 by the air pressure in the intake pipe 6.

[0022] The gas measuring instrument 1 may include a temperature regulator 11 that adjusts the temperature of the filter 7. The temperature regulator 11 is, for example, a heater provided in the intake piping 6. When the temperature regulator 11 applies heat to the intake piping 6, the miscellaneous gases adsorbed to the porous metal complexes 8b, 9b can be removed from the porous metal complexes 8b, 9b.

[0023] [Gas measuring device operation] The vacuum pump 5 operates to reduce the pressure in the internal space of the chamber 3. As a result, the sample gas 100 is drawn into the intake pipe 6. The drawn sample gas 100 passes through the first filter 8. At this time, oxygen gas and water vapor contained in the sample gas 100 are removed by the porous metal complex 8b of the first filter 8. Next, the sample gas 100 passes through the second filter 9. At this time, nitrogen gas and rare gases contained in the sample gas 100 are removed by the porous metal complex 9b of the second filter 9. As a result, the main components of the atmosphere in the sample gas 100 are removed, and the concentration of the target gas in the sample gas 100 increases. The target gas concentrated in the chamber 3 is detected by the gas sensor 2.

[0024] When the removal function of the filter 7 is to be restored, the operation of the gas sensor 2 is stopped and the vacuum pump 5 and the temperature regulator 11 are operated. As the temperature of the intake pipe 6 rises, the miscellaneous gases adsorbed on the porous metal complexes 8b and 9b are desorbed and exhausted through the chamber 3. In this way, the removal function of the filter 7 can be restored without removing the intake pipe 6.

[0025] [Summary of the embodiment] According to the gas measuring instrument 1, the filter 7 does not adsorb the target gas contained in the sample gas 100 in the atmosphere, and nitrogen gas, oxygen gas, or rare gas is removed from the sample gas 100, and the target gas is detected from the sample gas 100 by the gas sensor 2. Nitrogen gas, oxygen gas, or rare gas is contained in large amounts in the atmosphere and is a factor that reduces the detection sensitivity of the gas sensor 2. By removing the main component gas in the atmosphere by the filter 7, gas that reduces the detection sensitivity is removed and the target gas is relatively concentrated. Therefore, the gas measuring instrument 1 can improve the detection accuracy of the target gas in the atmosphere. In addition, according to the gas measuring instrument 1, since the target gas is relatively concentrated, there is no need to prepare a dedicated concentrator for each type of target gas, and the detection accuracy of the target gas can be simply improved. In other words, the gas measuring instrument 1 can provide a concentration function that can be used universally regardless of the type of gas sensor.

[0026] The gas measuring instrument 1 employs a filter 7 containing porous metal complexes 8b, 9b, which is less electrically active than general adsorption materials and can remove low molecular weight gases, thereby enabling the appropriate removal of nitrogen gas, oxygen gas, and rare gases.

[0027] In the gas measuring instrument 1, the filter 7 includes breathable bags 8a, 9a that contain the powdered porous metal complexes 8b, 9b. This makes it possible to adjust the amount and containment form of the porous metal complexes 8b, 9b according to the flow rate of the sample gas 100 or the internal shape of the intake piping 6, and reduces the risk of the powdered porous metal complexes 8b, 9b diffusing into the measurement system or the atmosphere.

[0028] In the gas measuring instrument 1, the filter 7 has a double filter structure consisting of the first filter 8 and the second filter 9. Therefore, when maintenance is required to restore the oxygen gas removal function, for example, an operator can replace only the first filter 8 requiring maintenance, without having to replace the entire filter 7. This enables the gas measuring instrument 1 to have improved maintainability.

[0029] [Variations] Although various exemplary embodiments have been described above, various omissions, substitutions, and modifications may be made without being limited to the above exemplary embodiments.

[0030] A plurality of gas sensors including the gas sensor 2 and a gas sensor of a different type from the gas sensor 2 may be disposed inside the chamber 3. The porous metal complexes 8b and 9b may be provided as adsorption members rather than powders. In this case, the gas measuring instrument 1 may not include the bags 8a and 9a. The porous metal complexes 8b and 9b may be disposed in any manner as long as they are disposed upstream of the gas sensor 2. The filter 7 may be constituted by a single filter or by three or more filters.

[0031] Fig. 2 is a schematic diagram showing a modified example of a gas measuring instrument according to a modified example. The gas measuring instrument 1A shown in Fig. 2 is different from the gas measuring instrument 1 shown in Fig. 1 in that the porous metal complexes 8b and 9b constituting the filter 7 are each stored in a container, but otherwise are the same. The following description will focus on the differences and omit redundant description.

[0032] As shown in Fig. 2, a first container 12a and a second container 12b are provided in the intake pipe 6 located upstream of the gas sensor 2. The first container 12a and the second container 12b are hollow. The first container 12a stores therein a porous metal complex 8b. The second container 12b stores therein a porous metal complex 9b.

[0033] The first container 12a and the second container 12b have an inlet and an exhaust port. The inlet of the first container 12a is configured to allow the introduction of a sample gas 100 from the atmosphere. The exhaust port of the first container 12a is connected to the inlet of the second container 12b. The exhaust port of the second container 12b is connected to the chamber 3. In this manner, the first container 12a and the second container 12b are connected in series and communicate with each other.

[0034] A first valve 13a is provided at the inlet of the first container 12a. The flow rate of the sample gas 100 flowing into the first container 12a is adjusted by controlling the first valve 13a. A second valve 13b is provided at the exhaust port of the first container 12a. The flow rate of the sample gas 100 exhausted from the first container 12a, that is, the flow rate of the sample gas 100 flowing into the second container 12b, is adjusted by controlling the second valve 13b. A third valve 13c is provided at the exhaust port of the second container 12b. The flow rate of the sample gas 100 exhausted from the second container 12b, that is, the flow rate of the sample gas 100 flowing into the chamber 3, is adjusted by controlling the third valve 13c. Note that some or all of the first valve 13a, the second valve 13b, and the third valve 13c may be mass flow controllers.

[0035] The first container 12a and the second container 12b are provided with temperature regulators 11a and 11b for adjusting the temperature. The temperature regulators 11a and 11b have the same configuration as the temperature regulator 11, and can remove miscellaneous gases adsorbed in the porous metal complexes 8b and 9b from the porous metal complexes 8b and 9b.

[0036] In the gas measuring instrument 1A configured as described above, the sample gas 100 flows into the first container 12a, and oxygen gas is removed from the sample gas 100 by the porous metal complex 8b, and the sample gas is sent to the second container 12b. Then, in the second container 12b, nitrogen gas or rare gas is removed from the sample gas 100 by the porous metal complex 9b, and the sample gas is sent to the chamber 3. In addition, since the first container 12a and the second container 12b have a structure in which their inlet and exhaust ports can be opened and closed, the powdered porous metal complexes 8b, 9b can reduce the risk that the powdered porous metal complex diffuses into the measurement system or the atmosphere. In this way, the first container 12a and the porous metal complex 8b constitute the first filter 8, the second container 12b and the porous metal complex 9b constitute the second filter 9, and the first container 12a, the porous metal complex 8b, the second container 12b, and the porous metal complex 9b constitute the filter 7 in the gas measuring instrument 1. Therefore, gas measuring instrument 1A has the same effects as gas measuring instrument 1. [Explanation of symbols]

[0037] 1, 1A...gas measuring instrument, 2...gas sensor, 7...filter, 8...first filter, 9...second filter, 8a, 9a...bag body, 8b, 9b...porous metal complex, 12a...first container, 12b...second container, 100...sample gas.

Claims

1. A filter comprising a porous metal complex in which a metal ion and an organic ligand are bonded, for removing interfering gases from a sample gas in the atmosphere; a gas sensor for detecting a target gas from the sample gas that has passed through the filter; Equipped with The miscellaneous gas is at least one gas selected from nitrogen gas, oxygen gas, and rare gas, The filter includes a first filter made of the porous metal complex that mainly removes oxygen gas, and a second filter made of the porous metal complex that is disposed downstream of the first filter and mainly removes nitrogen gas and rare gases. Gas measuring instrument.

2. The gas measuring instrument according to claim 1 , wherein the first filter and the second filter each have a breathable bag that contains the porous metal complex in powder form.

3. 2. The gas measuring instrument of claim 1, wherein the first filter and the second filter have a container that contains the porous metal complex in powder form, the container including an inlet for introducing the sample gas and an exhaust port for exhausting the sample gas.

4. the first filter is made of the porous metal complex in which a metal ion and tetracyanoquinodimethane are bonded, 2. The gas measuring device according to claim 1, wherein the second filter is made of the porous metal complex in which a metal ion is bonded to terephthalic acid or methylene.

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