JP2018091757A - Gas detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable detection of gas in a region in a relatively flexible position to the arrangement of the device.SOLUTION: The gas detector includes: a light emitting unit 113 for emitting detection light; a light receiving unit 114 for receiving detection light passing through a detection gas region; a light emission side light guide body 131 for guiding the detection light emitted from the light emitting unit 113 to the detection gas region; a light reception side light guiding body 132 for guiding detection light passing through the detection gas region to the light receiving unit 114; and a measurement processing unit 116 for detecting gas based on the detection light received by the light receiving unit 114.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a gas detection device capable of detecting a gas at a location away from the device.

  As a conventional gas detection device, a detection light emitting unit that emits detection light, a light receiving unit that receives reflected light reflected from the object when the detection light is applied to the object, and the light receiving unit A column density measurement unit that measures the column density of the gas to be detected from the reflected light, an optical path length measurement unit that measures an optical path length of the detection light from the detection light emitting unit to the object, the column density, and the A gas concentration detection device having a concentration calculation unit that calculates the concentration of the gas to be detected based on the optical path length is known (for example, see Patent Document 1).

  According to this, the density | concentration of the to-be-detected gas distributed spatially can be measured as an average or locally.

JP 2014-055558 A

  However, in the device that emits detection light and receives the reflected light as described above, the gas that exists in the space that linearly connects between the radiation part and the reflection object and between the reflection object and the light reception part Can be detected, but gas in a region away from such a space cannot be detected.

  The present invention has been made in view of the above points, and it is an object of the present invention to be able to detect gas in a region at a relatively flexible position with respect to the arrangement of the apparatus.

To achieve the above objective,
The first invention is
A gas detector,
A light emitting section for emitting detection light;
A light receiving unit that receives the detection light that has passed through the detection gas region;
A light-emitting side light guide that guides detection light emitted from the light-emitting unit to the detection gas region;
A light-receiving-side light guide that guides detection light that has passed through the detection gas region to the light-receiving unit;
A measurement processing unit for detecting gas based on the detection light received by the light receiving unit;
It is provided with.

  Thereby, the light received and emitted by the light receiving unit and the light emitting unit can be guided through the light guide, so that the position of the device including the light receiving unit and the light emitting unit can be remotely and relatively flexible. It is possible to detect the gas in the region.

The second invention is
A gas detection device according to a first invention,
A measuring unit containing the light emitting unit, the light receiving unit, and the measurement processing unit;
An attachment unit detachably provided in the measurement unit, and having a connection unit to which the light emitting side light guide and the light receiving side light guide can be connected;
With
The measurement unit is based on the detection light that is reflected from the object and received by the light receiving unit when the detection light emitted from the light emitting unit is irradiated on the object in a state where the attachment unit is not attached. Thus, the column density of the detection gas can be obtained.

  Thereby, the gas detection device can be easily configured by using a device capable of obtaining the column density of the detection gas as described above and mounting the attachment portion on the device.

The third invention is
A gas detection device according to a second invention,
The attachment unit further includes an attenuation filter that attenuates at least one of the detection light emitted from the light emitting unit and the detection light received by the light receiving unit.

  Thereby, it is possible to easily set the detection sensitivity.

The fourth invention is:
The gas detection device according to any one of the first to third aspects, further comprising:
A detection gas region unit is provided that allows detection light emitted from the light-emitting side light guide to pass through the detection gas region and enter the light-receiving side light guide.

  Accordingly, if the detection gas region unit is installed at a place where gas is to be detected, remote detection can be easily performed even if the installation position of the measurement unit is flexibly set.

The fifth invention is:
A gas detector according to a fourth invention,
The detection gas region unit is
A retro-reflector that reflects the detection light emitted from the light-emitting side light guide and makes it incident on the light-receiving side light guide, or diffusely reflects the detection light emitted from the light-emitting side light guide to the light-receiving side light guide It has a diffuse reflector to make it incident,
The detection gas region is provided between the light-emitting side light guide and the light-receiving side light guide and the retroreflector or the diffuse reflector.

The sixth invention is:
The gas detection device according to any one of the first to fifth aspects,
The light emitting side light guide is configured using a single mode optical fiber,
The light-receiving side light guide is configured using a multimode optical fiber.

  Thus, highly sensitive detection can be easily performed.

  According to the present invention, it is possible to detect gas in a region of a relatively flexible position with respect to the arrangement of the apparatus.

It is a partial section front view showing typically composition of a measurement unit. It is sectional drawing which shows the structure of a detection gas area | region unit typically.

  Hereinafter, as an embodiment of the present invention, an example of a gas detection apparatus including a measurement unit 100 as shown in FIG. 1 and a detection gas region unit 200 as shown in FIG. 2 will be described.

  The measurement unit 100 is configured by attaching an attachment unit 120 to a measurement unit 110.

  The measurement unit 110 includes, for example, an operation unit 111 including a power switch 111a and a measurement start switch 111b, a display unit 112 that displays measurement results, and the like, for example, an emission beam diameter of about 1.2 mm and a wavelength of 1.65 μm. A light emitting unit 113 that emits detection light such as laser light, a light receiving unit 114 that receives detection light that has passed through a detection gas region (a region in which the presence of a detection target gas is assumed), and detection light that is received by the light receiving unit 114 Based on the above, a measurement processing unit 116 that detects gas is housed in a housing 115 and configured. As the measurement unit 110 as described above, for example, a so-called portable small-sized gas detector that can detect a generation source of methane gas or a leakage point from a remote location by irradiating a laser beam emitted from the light emitting unit 113 to the inspection location. Etc. can be applied.

  The attachment unit 120 attached to the measurement unit 110 includes a housing 121 that can be attached to and detached from the housing 115 of the measurement unit 110. The housing 121 is provided with FC receptacles 122 and 123 to which the light emitting side light guide 131 or the light receiving side light guide 132 can be connected, respectively. As the light emitting side light guide 131, for example, a single mode optical fiber can be used, and as the light receiving side light guide 132, for example, a multimode optical fiber can be used. Further, if necessary, a collimating lens such as an aspheric lens 122a is provided between the light emitting unit 113 and the FC receptacle 122, or between the FC receptacle 123 and the light receiving unit 114, for example, within two sheets. A detachable attenuation filter 124 may be provided.

  On the other hand, in the detection gas region unit 200, the light guides 131 and 132 are connected to the housing 210, and the detection gas can flow inside the housing 210. More specifically, for example, the housing 210 is configured by assembling a base plate 211, a body portion 212, and a cover plate 214. Light guides 131 and 132 are connected to the cover plate 214 so that laser light can enter and exit through the lenses 131a and 132a and the window glass 231. The body 212 is provided with, for example, a gas inlet 212a through which detection gas flows in the direction indicated by arrow A and a gas outlet 212b through which detection gas flows out in the direction indicated by arrow B by a pump (not shown). An O-ring 213 is provided at the connection portion between the base plates 211 and 212, while an O-ring 232 and a retainer 234 are provided between the cover plates 214 and 231 so that detection gas leaks at these locations. Is to be prevented. A retro-reflector 222 is provided inside the housing 210 via a holder 221 so that laser light that has entered the housing 210 from the light-emitting side light guide 131 is reflected toward the light-receiving side light guide 132. ing.

  In the gas detection device configured as described above, the laser light emitted from the light emitting unit 113 of the measuring unit 110 is collimated by the aspherical lens 122a, and then detected gas region unit via the light emitting side light guide 131. 200, the diameter of the beam is reduced to about 1.6 mm by the lens 131a, and is introduced into the space (detection gas region) in the detection gas region unit 200. The light that has passed through the detection gas region is reflected by the retroreflector 222, passes through the detection gas region again, and is received by the light receiving unit 114 of the measuring unit 110 via the light receiving side light guide 132 and the attenuation filter 124. In the optical path of the laser light, for example, when methane gas is present when it passes through the detection gas region in the detection gas region unit 200 once by a certain distance, the light is absorbed according to its concentration. Therefore, a predetermined calculation is performed in the measurement processing unit 116 based on the laser beam received by the light receiving unit 114, and thereby the gas flowing in the detection gas region unit 200 is detected. That is, for example, the concentration of the detection gas can be measured to detect whether or not the concentration of the detection gas has reached the lower explosion limit.

  As described above, the detection gas region unit 200 and the measurement unit 100 are connected by the light guides 131 and 132, so that if the detection gas region unit 200 is installed in a place where gas is to be detected, the measurement unit 100 Even if the installation position is set flexibly, it can be easily detected remotely. That is, the detection can be performed without carrying the apparatus to a place where the gas is to be detected, such as a suction type gas concentration analyzer, and the cost required for the apparatus and the detection can be easily reduced. .

  In addition, since it is not necessary to provide an electrical circuit in the detection gas region unit 200, if the measurement unit 100 is installed in a place where explosion prevention is not required or where there are few restrictions, the gas detection device as a whole is provided. The explosion-proof property can be easily increased.

  In addition, since the measurement unit 100 can be easily provided in the thermostatic chamber, or a measure against vibration is taken, it is possible to easily improve detection accuracy.

  Here, in the space in the detection gas region unit 200, not only the gas flows in and out through the gas inlet 212a and the gas outlet 212b, but the optical path of the laser light is positioned in a naturally circulating atmosphere. It may be. Alternatively, the detection gas region unit 200 may be connected to a predetermined gas pipe so that the gas in the gas pipe can be detected. In addition, the detection gas region units 200 are installed at a plurality of locations, the light guides are sequentially connected in a chain shape, and both ends thereof are connected to one measurement unit 100, and the gas is measured at any of the plurality of locations or in total. It is also possible to detect that the concentration has increased. In addition, the detection gas area unit 200 can be fixed to a jig such as a fishing rod, for example, so that local gas in a place where the hand cannot reach such as a ceiling can be easily detected.

  In the above example, the aspherical lens 122a, the lenses 131a and 132a, the attenuation filter 124, and the like are used as the components of the optical system. It may be set according to the required light receiving and emitting intensity, gas detection sensitivity, and the like. For example, as described above, as the measurement unit 110, a portable small gas detector, that is, a laser beam emitted from the light emitting unit 113 is irradiated to an inspection location, thereby detecting a source of methane gas or a leakage location from a remote location. In the case of applying a detector or the like that can be used, such a detector usually has a relatively large light emission intensity, but is often set to receive weak light. By providing 124, it is possible to easily adjust the light receiving sensitivity of the light receiving unit 114.

  However, by using the attachment unit 120 that can be attached to and detached from the measurement unit 110 as described above, a portable small gas detector or the like can be easily applied as the measurement unit 110. However, as the measurement unit 100, Not only, but also in the case where a measuring unit 110 and an attachment unit 120 are provided integrally, remote sensing is possible by connecting the sensing gas region unit 200 via the light guides 131 and 132. The effect that can be easily performed is obtained similarly.

  In the above example, the laser beam is reflected by using the retro-reflector 222. However, the present invention is not limited to this. If sufficient light-receiving sensitivity is obtained, the laser beam is coarsely substituted instead of the retro-reflector 222. It may be irregularly reflected on the surface. In this case, the attenuation filter 124 may be easily omitted. Further, for example, the emission part of the light-emitting side light guide 131 and the incident part of the light-receiving side light guide 132 are opposed to each other with the optical axis aligned so that the laser light passes through the atmosphere between the light guides 131 and 132. Or you may.

  Moreover, the use of the above gas detection apparatus is not specifically limited, For example, you may apply to the driving | running state monitoring by the detection of methane gas in a biogas generation plant etc. Here, when applied to such a plant, in order to reduce or prevent contamination of the optical system components, a filter for removing impurities in the circulating gas may be installed. In addition, for example, in detecting abnormalities such as gas leaks in a marine natural gas engine, it is useful to apply a gas detector that can be remotely measured as described above. Further, the type of gas to be detected is not limited to methane, and can be variously set by appropriately selecting the wavelength of the laser beam.

DESCRIPTION OF SYMBOLS 100 Measurement unit 110 Measurement part 111 Operation part 111a Power switch 111b Measurement start switch 112 Display part 113 Light emission part 114 Light reception part 115 Case 116 Measurement processing part 120 Attachment part 121 Housing 122 FC receptacle 122a Aspherical lens 123 FC receptacle 124 Attenuation filter 131 Light-Emitting Light Guide 131a Lens 132 Light-Receiving Light Guide 131b Lens 200 Detection Gas Area Unit 210 Housing 211 Base Plate 212 Body 212a Gas Inlet 212b Gas Outlet 213 O-ring 214 Cover Plate 221 Holder 222 Retroreflector 231 Window Glass 232 O Ring 234 retainer

Claims (6)

A light emitting section for emitting detection light;
A light receiving unit that receives the detection light that has passed through the detection gas region;
A light-emitting side light guide that guides detection light emitted from the light-emitting unit to the detection gas region;
A light-receiving-side light guide that guides detection light that has passed through the detection gas region to the light-receiving unit;
A measurement processing unit for detecting gas based on the detection light received by the light receiving unit;
A gas detection device comprising: The gas detection device according to claim 1,
A measuring unit containing the light emitting unit, the light receiving unit, and the measurement processing unit;
An attachment unit detachably provided in the measurement unit, and having a connection unit to which the light emitting side light guide and the light receiving side light guide can be connected;
With
The measurement unit is based on the detection light that is reflected from the object and received by the light receiving unit when the detection light emitted from the light emitting unit is irradiated on the object in a state where the attachment unit is not attached. The gas detector is configured to obtain the column density of the detection gas. The gas detection device according to claim 2,
The attachment unit further includes an attenuation filter that attenuates at least one of the detection light emitted from the light emitting unit and the detection light received by the light receiving unit. The gas detection device according to any one of claims 1 to 3, further comprising:
A gas detection device comprising: a detection gas region unit that causes detection light emitted from the light emitting side light guide to pass through a detection gas region and enter the light receiving side light guide. The gas detection device according to claim 4,
The detection gas region unit is
A retro-reflector that reflects the detection light emitted from the light-emitting side light guide and makes it incident on the light-receiving side light guide, or diffusely reflects the detection light emitted from the light-emitting side light guide to the light-receiving side light guide It has a diffuse reflector to make it incident,
A gas detection device, wherein the detection gas region is provided between the light-emitting side light guide and the light-receiving side light guide and the retroreflector or the irregular reflector. A gas detection device according to any one of claims 1 to 5,
The light emitting side light guide is configured using a single mode optical fiber,
The gas detector according to claim 1, wherein the light-receiving side light guide is configured using a multimode optical fiber.

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