JP6225369B2 - Gas detection unit - Google Patents

Description

  The present invention relates to a gas detection unit including a detection unit that detects a gas to be detected inside a casing.

  Conventionally, when measuring a component to be measured in a sample gas having a relatively low concentration, gas concentration treatment by a thermal desorption method is often performed to increase the concentration of the component to be measured. In the thermal desorption method, first, a sample gas is circulated through a concentration tube filled with an adsorbent that mainly adsorbs a component to be measured, and the component to be measured contained in the sample gas is adsorbed to the adsorbent. Then, after the component to be measured is sufficiently adsorbed, the temperature of the adsorbent is rapidly raised while flowing the carrier gas through the concentration tube. As a result, the adsorbed component to be measured is desorbed in a short time and can be introduced into the downstream gas sensor at a high concentration.

  In Patent Document 1, a sample gas is circulated through a collection means so that the sample component is adsorbed on the collection means, and then the flow path switching means is switched to inactivate the sample component adsorbed on the collection means. An odor measuring device is described which is introduced into an odor detecting means after being desorbed into a gas and mixed with oxygen or a gas containing oxygen.

  Further, in Patent Document 2, as an adsorption concentrator used in an exhaust gas treatment apparatus, an adsorption means is constituted by an adsorption part for adsorbing a gas and a desorption part for desorbing the adsorbed gas, and is adsorbed by the desorption part. There is described an adsorption concentrating apparatus that includes a desorption gas supply means for supplying a desorption gas for desorbing the organic solvent, and periodically switches between the adsorption section and the desorption section. This apparatus includes an inlet concentration measuring means for measuring the inlet concentration of the adsorption means and an adsorption / desorption cycle adjusting means for adjusting the adsorption / desorption cycle in response to a signal from the inlet concentration measuring means.

JP-A-11-118744 JP 2006-247595 A

  The odor measuring apparatus of Patent Document 1 requires a gas supply unit that supplies an inert gas, a mixing unit that mixes oxygen gas, and the like. Moreover, the adsorption | suction means in the adsorption concentration apparatus of patent document 2 was comprised with the adsorption tower filled with the adsorbent. As described above, since the apparatus of Patent Documents 1 and 2 has a large-scale configuration, it cannot be applied to a handy-type small-sized gas detector or the like, for example, at a site where a target gas to be detected exists.

  Accordingly, an object of the present invention is to provide a gas detection unit that can detect and concentrate a detection gas on a small scale.

FEATURES configuration of the gas sensing unit according to the present invention for achieving the above object, heating the one surface of the heat resistant substrate, suction means for the gas to be detected are desorbed adsorbed by temperature change, and, on the other side A measurement unit included in the detected gas upstream of the adsorption unit, and provided with an adsorption unit provided with a means and a detection unit for detecting the detected gas desorbed from the adsorption unit An adsorption channel through which the gas to be detected flows when adsorbed on the adsorption unit, and a desorption channel through which the gas to be detected flows when a component to be measured contained in the gas to be detected is desorbed from the adsorption unit. These flow paths can be switched, and the desorption flow path is provided with a removing means for removing the measured component contained in the detected gas .

  In this configuration, by allowing a gas to be detected containing a low concentration component to be measured to flow down in the adsorption portion, it is possible to cause the adsorption component to adsorb and concentrate the component to be measured. In this state, when the heating unit is heated to heat the adsorption unit, the concentrated component to be measured can be desorbed from the adsorption unit. The concentrated component to be measured thus desorbed can be measured by the detector.

  Therefore, according to the present configuration, the adsorption unit and the detection unit can be disposed inside a housing such as a handy type gas detector or an alarm device disposed on the ceiling or wall. With a simple configuration, the gas to be detected can be concentrated and detected.

Gas detection unit according to the present invention, upstream of the suction unit, a suction flow path gas to be detected flows in the measured components contained in gas to be detected is adsorbed to the adsorption unit, the gas to be detected A desorption channel through which a gas to be detected flows when a component to be measured is desorbed from the adsorption unit, and the channels can be switched, and the gas to be detected is disposed in the desorption channel. The removal means which removes the to-be-measured component contained in is provided .

  According to this configuration, the flow path can be switched between when the component to be measured contained in the detected gas is adsorbed by the adsorption unit and when the component to be measured contained in the detected gas is desorbed from the adsorption unit. it can. When the gas to be detected flows down the desorption channel, the component to be measured contained in the gas to be detected can be removed by the removing means. As a result, when the component to be measured contained in the gas to be detected is desorbed by heating, the component to be measured contained in the gas to be detected can be removed by the removing means upstream of the adsorption portion using the desorption channel. . Therefore, in this configuration, since it is possible to prevent detection of the signal of the measured component contained in the detected gas before concentration, the concentration of the measured component contained in the concentrated detected gas can be calculated more accurately. Can do.

It is the schematic which shows the gas detection unit of this invention. 2 is a graph showing results when a peak of diketone A is detected in Example 1. FIG. It is the schematic of the gas detection unit of Example 2. FIG. It is the graph which showed the relationship between the temperature and signal in Example 2 (it uses as a type of alarm device which attaches a gas detection unit to a wall). It is the graph which showed the relationship of the temperature and signal in Example 3 (when performing a cleaning process). FIG. 6 is a schematic diagram of a gas detection unit according to a fourth embodiment. FIG. 10 is a schematic diagram of a gas detection unit according to a fifth embodiment. It is the schematic of another Example of an adsorption | suction part (Example 8). It is the schematic of another Example of an adsorption | suction part (Example 8). It is the schematic of another Example of an adsorption | suction part (Example 9). It is the schematic of another Example of an adsorption | suction part (Example 10).

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
The present invention is a gas detection unit including a detection unit that detects a gas to be detected inside a casing. Examples of the gas detection unit include, but are not limited to, a small handy type gas detector.

  As shown in FIG. 1, the gas detection unit X of the present invention has an adsorption means 21 for adsorbing and desorbing a gas to be detected by temperature change on one surface of a heat-resistant substrate 10, and a heating means on the other surface. The housing 40 is provided with an adsorbing unit 20 having 22 and a detecting unit 30 for detecting a gas to be detected desorbed from the adsorbing unit 20.

  The heat resistant substrate 10 may be any substrate having heat resistance, and for example, a substrate made of ceramic, metal, heat resistant resin, or the like can be used. In the case of a ceramic substrate, an alumina substrate or an aluminum nitride substrate may be used. The size of the heat-resistant substrate 10 is determined by factors such as the amount of adsorption, adsorption efficiency, and power consumption, but is preferably approximately 3 mm × 3 mm × 1 mm or less. However, the shape of the heat resistant substrate 10 is not necessarily rectangular.

  As long as the adsorption | suction means 21 is an aspect which can adsorb / desorb the gas adsorb | sucked by the temperature change, what kind of means is applicable. Specifically, the adsorption means 21 is poor in reactivity with the detected gas at the operating temperature, and is capable of adsorbing the detected gas at room temperature and desorbing the adsorbed detected gas by heating with the heating means 22. I just need it. As such an adsorbing means 21, a porous solid can be used. For example, inorganic materials such as silica, alumina, carbon, and metal oxide, and organic materials such as a synthetic resin can be used.

  As the carbon-based adsorption means 21, Tenax GR (manufactured by GL Science Co., Ltd.) or carbon black can be used. When the surface of carbon black is oxidized to be moderately acidic, alkaline components such as ammonia and amine can be selectively adsorbed well. An acidic substance may be attached to the carbon black. The terminal of the carbon black structure may be chemically modified with an acidic group such as a sulfo group. If the surface of the carbon black is made moderately alkaline, acidic components such as organic acids and mercaptans can be selectively adsorbed well. An alkaline substance may be attached to the carbon black. The terminal of the carbon black structure may be chemically modified with an alkaline group such as an amino group.

  The thickness of the suction means 21 can be appropriately set depending on factors such as the amount of suction and power consumption, but is preferably approximately 20 to 300 μm.

The heating means 22 may be an embodiment that can be disposed on the heat-resistant substrate 10. For example, the heater 22 may be a heater in which a platinum thin film is patterned, but is not limited thereto. The heating means 22 may be connected to a Peltier element for temperature control.
The heating temperature by the heating means 22 is preferably 400 ° C. or lower when using an organic gas or an organic adsorbent, and 500 ° C. or lower when using an inorganic gas and an inorganic adsorbent, in order to prevent the adsorption means 21 from being altered.

  The detection unit 30 may be in any form as long as it detects the gas to be detected, and a known semiconductor sensor element, catalytic combustion sensor element, electrochemical sensor element, or the like can be used. For example, the semiconductor gas detection element includes a hot-wire semiconductor gas detection element and a substrate type semiconductor gas detection element, but is not limited thereto. In a semiconductor gas detection element, for example, tin oxide or indium oxide may be used as a main component of the gas sensitive part, and molybdenum oxide, lead oxide, or the like may be added so that a low concentration odor component can be detected. . Further, the gas sensitive layer may be configured to have tungsten oxide as a main component and have VOC selectivity so that a low concentration VOC (volatile organic compound) gas can be detected.

  The shape of the casing 40 of the gas detection unit X is not particularly limited as long as the suction unit 20 and the detection unit 30 are accommodated therein. However, in the present embodiment, the casing 40 is rectangular in top view. And an example of a thick plate-like shape. Examples of the usage form of the gas detection unit X include an aspect in which the gas detection unit X is installed on a ceiling or a wall, or an aspect of a handy type.

  The gas detection unit X of the present invention includes a gas suction port 1, a gas discharge port 2, a gas flow path 3, a three-way valve 4, and a pump P in addition to the above configuration.

  In this embodiment, the three-way valve 4 is set so that the gas to be detected containing a low concentration component to be measured (for example, an odor component) flows down to the gas outlet 2 side, and the gas to be detected is allowed to flow by a certain amount. The component to be measured can be adsorbed on the adsorption means 21 of the unit 20 and concentrated. Next, when the heating unit 22 is heated to heat the adsorption unit 21, the three-way valve 4 is set so that the concentrated odor component is desorbed from the adsorption unit 21 and the desorbed gas flows down to the detection unit 30 side. Then, a small amount of carrier gas (air, helium, nitrogen, etc.) is caused to flow down from the pump P for a certain time. At this time, it is possible to provide a flow rate control means (not shown) for controlling the flow rate.

  With such a configuration, the gas detection unit X of the present invention has the adsorption unit 20 and the detection unit 30 arranged inside a housing such as a handy type gas detector or an alarm device arranged on the ceiling or wall. Therefore, the gas to be detected can be concentrated and detected with a small configuration.

As shown in FIG. 7, the gas flow path 3 includes an adsorption flow path 3 a through which the gas to be detected flows when the component to be measured contained in the gas to be detected is adsorbed by the adsorption section 20 upstream of the adsorption unit 20. the desorption passage 3b to be measured component contained in the gas to be detected is to be detected gas flows during the desorption from the adsorption unit, Ru comprising a. In this case, it is preferable to provide a switching control means (not shown) for switching between the adsorption channel 3a and the desorption channel 3b. In this configuration, the flow path of the gas to be detected in the case where the measurement component contained in the detection gas is adsorbed by the adsorption unit 20 and the case where the measurement component contained in the detection gas is desorbed from the adsorption unit 20 Can be switched.

Further, the desorption channel 3b is provided with a removing means 60 for removing the component to be measured contained in the gas to be detected . In the present configuration, the measured component contained in the detected gas can be removed by the removing means 60 as the detected gas flows down the desorption channel 3b. Thus, when the component to be measured contained in the gas to be detected is desorbed by heating, the component to be measured contained in the gas to be detected by the removing means 60 upstream of the adsorption unit 20 using the desorption channel 3b. Can be removed. Therefore, in this configuration, since it is possible to prevent detection of the signal of the measured component contained in the detected gas before concentration, the concentration of the measured component contained in the concentrated detected gas can be calculated more accurately. Can do.

[Example 1]
Examples of the present invention will be described.
In order to test the performance of the adsorption unit 20 in the gas detection unit X of the present invention, a gas to be detected containing diketone A (a kind of odor component; 1 ppm) as a component to be measured was brought into contact with the adsorption unit 20.

  The adsorbing unit 20 applies 1.4 mg of carbon material adsorbent Tenax GR (manufactured by GL Science Co., Ltd.) to one surface of an alumina substrate 10 (3 mm × 3 mm × 1 mm) to form an adsorbing means 21, and platinum on the other surface Was patterned to form a meander pattern to form a heating means 22.

  After bringing the sample gas into contact with the adsorbing unit 20, the heating means 22 is heated to 280 ° C. and introduced into gas chromatography (model number XG-100V, manufactured by Shin Cosmos Electric Co., Ltd.) as a 10 mL concentrated gas. When measured continuously, a large peak of diketone A was obtained (FIG. 2 (a)).

As a result, it was recognized that even a low-concentration odor component can be introduced into the detection unit 30 in a state of being concentrated to a level sufficient for gas detection by being adsorbed and desorbed by the adsorption unit 20.
In addition, after obtaining a large peak of diketone A, the heating means 22 was heated again to detect diketone A. As a result, no peak of diketone A was detected (FIG. 2B). Therefore, it was recognized that even the small heating means 22 disposed in the small adsorption unit 20 as in the present configuration can sufficiently desorb the gas to be detected.

[Example 2]
The gas detection unit X of the present invention was used as a type of alarm attached to a wall (FIG. 3).

  The components to be measured were allowed to stand at room temperature for about 30 hours to be adsorbed by the adsorption means 21 of the adsorption unit 20, and then the heating means 22 was heated to 300 ° C. to desorb the components to be measured from the adsorption means 21. At this time, the signal of the component under measurement could be obtained by the detection unit 30 (FIG. 4). Accordingly, it was recognized that the gas detection unit X of the present invention can be used as an alarm device of a type attached to a wall and used for monitoring low concentration components to be measured, for example, VOC and odor components.

Example 3
In the gas detection unit X according to the second embodiment, the component to be measured is adsorbed by the adsorption unit 21 of the adsorption unit 20, and then the heating unit 22 is heated so that the adsorption unit 21 is also cleaned. However, there may be cases where the component to be measured is weak against heat or it is difficult to remove the interfering component. In such a case, in order to clean the adsorption means 21, the timing for heating the heating means 22 may be set separately. In FIG. 5, before the component to be measured is adsorbed by the adsorption unit 21, the heating unit 22 is heated to 350 ° C. to clean the adsorption unit 21 (first cleaning step). The case where the heating means 22 was heated to 350 ° C. after desorption at 250 ° C. to clean the adsorption means 21 (second cleaning step) was shown.

  As a result, the adsorption unit 21 can be cleaned at a temperature higher than the temperature at which the component to be measured is desorbed from the adsorption unit 21, so that the adsorption unit 21 can be reliably cleaned without denaturing the component to be measured. Can do.

  During heating in the cleaning process, a signal of the measured component before concentration of the measured component is detected. If the detected signal level is below the detection lower limit, it can be ignored, but if it is expected to be above the detection lower limit, the signal before heating in the cleaning process is subtracted or multiplied by a certain coefficient (for example, 0.9). Thus, the concentration of the component to be measured included in the gas to be detected can be calculated.

Example 4
The gas detection unit X of the present invention was used as a handy type gas detector (FIG. 6).

Atmospheric gas is sucked by the pump P for a predetermined time to cause the component to be measured to be adsorbed to the adsorption means 21 of the adsorption unit 20, and then the heating means 22 is heated to 300 ° C. to cause the component to be measured to be desorbed from the adsorption means 21 It was. At this time, the signal of the component under measurement could be obtained by the detection unit 30 (results are not shown). Accordingly, it was recognized that the gas detection unit X of the present invention can be used as a handy type gas detector and used for applications such as monitoring of low concentration components to be measured.
By using it as a handy type gas detector as in this embodiment, for example, the total amount of hydrocarbons (THC) in a relatively low concentration environment is measured on site, and if the value is high, it is measured while moving. Therefore, it is possible to search for the generation source.

Example 5
The gas detection unit X of the present invention was used as a handy type gas detector (FIG. 7). In the present embodiment, upstream of the adsorption unit 20, the adsorption flow path 3 a through which the gas to be detected flows when the component to be measured contained in the gas to be detected is adsorbed by the adsorption unit 20, and the object to be contained in the gas to be detected. A desorption channel 3b through which the gas to be detected flows when the measurement component is desorbed from the adsorption unit is provided. The desorption channel 3b is provided with a removing means 60 for removing the component to be measured contained in the gas to be detected.

In the present configuration, the measured component contained in the detected gas can be removed by the removing means 60 as the detected gas flows down the desorption channel 3b. As a result, when the gas to be detected is desorbed by heating, the component to be measured contained in the gas to be detected is removed by the removing means 60 upstream of the adsorption unit 20, and the component to be measured contained in the gas to be detected before concentration. Therefore, it is possible to calculate the concentration of the component to be measured more accurately.
Also in the present embodiment, it is possible to search for a source of the total hydrocarbon amount (THC) by measuring while moving the handy type gas detector.

Example 6
In the embodiment described above, it is possible to provide between the adsorption unit 20 and the detection unit 30 a filter unit that can eliminate the influence of interference components, or a column unit that can measure the concentration of a plurality of components to be measured (FIG. Outside). The column portion may be either a packed column (packed column) or a capillary column, and may be combined with a porous membrane.

  By providing the filter unit, it is possible to more accurately calculate the concentration of the component to be measured contained in the gas to be detected in a state where the influence of the disturbing component is eliminated. Further, by providing the column part, it is possible to separate a plurality of components to be measured and measure their concentrations, so that the concentration of each component to be measured can be calculated more accurately.

Example 7
In the embodiment described above, a plurality of detection units 30 having different characteristics may be provided. Thereby, when the gas to be detected contains a plurality of components to be measured, the plurality of components to be measured can be measured by each of the plurality of detection units 30.

Example 8
In the embodiment described above, the adsorbing portion 20 (adsorbing means 21) may be arranged so as to be orthogonal to the gas flow path 3 (FIG. 8). In this configuration, the gas to be detected can be adsorbed at an angle orthogonal to the adsorbing means 21, so that the adsorption efficiency is improved.

  Moreover, it is good also as an aspect which provides two adsorption | suction parts 20 (FIG. 9). In this configuration, the heating means 22 of the pair of adsorption portions 20 are arranged in a so-called V shape with the facing portions and the ends of the pair of adsorption portions 20 in contact with each other. By providing two adsorption portions 20, the opportunity for the component to be measured contained in the gas to be detected to be adsorbed by the adsorption means 21 can be increased, so that the adsorption efficiency is improved.

Example 9
In the suction part 20 of the embodiment described above, the suction means 21 may be sandwiched between the heat-resistant substrates 10 and the heating means 22 may be provided on each outer surface side of the suction part 20 (FIG. 10). In this configuration, since the heat transfer efficiency to the adsorption unit 21 is improved, the detected gas adsorbed by heating by the heating unit 22 can be desorbed more quickly.

Example 10
In the suction unit 20 of the above-described embodiment, the two heat-resistant substrates 10 may be combined to form the multilayer substrate 11, and the suction means 21 may be provided on each outer surface side of the multilayer substrate 11 (FIG. 11). In this configuration, the heating unit 22 is provided on the opposing surfaces of the two heat resistant substrates 10, so that the heating unit 22 is provided inside the multilayer substrate 11. The multilayer substrate 11 can be formed by laminating and pressing a green sheet including the heating means 22 and firing.

  In this configuration, by providing two adsorption means 21, it is possible to increase the chance that the component to be measured contained in the gas to be detected is adsorbed by the adsorption means 21, so that the adsorption efficiency is improved.

  The gas detection unit of the present invention can be used for a gas detection unit that includes a detection unit that detects a gas to be detected inside the casing.

X Gas detection unit 10 Heat-resistant substrate 20 Adsorption part 21 Adsorption means 22 Heating means 30 Detection part 40 Case

Claims (1)

An adsorbing means for adsorbing and desorbing a gas to be detected by temperature change on one surface of the heat-resistant substrate, and an adsorbing section having a heating means on the other surface
A detection unit that detects a gas to be detected desorbed from the adsorption unit, and a housing ,
Upstream of the adsorption unit, an adsorption flow path through which the gas to be detected flows when the component to be measured contained in the gas to be detected is adsorbed to the adsorption unit, and a component to be measured contained in the gas to be measured are supplied from the adsorption unit. And a desorption channel through which the gas to be detected flows when desorbing, and these channels can be switched, and the desorption channel removes the component to be measured contained in the gas to be detected. Gas detection unit with means .

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