JPH0552747U - Optical fiber gas sensor for measuring gas concentration in oil - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a compact optical fiber gas sensor for measuring the concentration of gas contained in insulating oil by light. A double tube structure comprising an outer cylinder 1 and an inner cylinder 2 concentrically arranged in the outer cylinder and provided with a gas-liquid separation membrane, wherein both ends of the double tube are annular ends. The gas-liquid separating cylinder portion A, which is sealed by the plates 3a and 3b and has an annular closed space 4 into which the gas concentration measuring oil flows between the outer cylinder 1 and the inner cylinder 2, is
And a porous inner cylinder 8 concentrically arranged in the outer cylinder, which has a double tube structure. One end of the double tube is sealed with an annular end plate 9 to form an outer cylinder 7. Concentration of gas sent from the optical fiber through the inner cylinder of the sensor outer cylinder part B of the gas detection cell enclosed in the annular space of the sensor outer cylinder part B in which an annular space 10 having one end opening is formed between the inner cylinder 8 and the inner cylinder 8. Optical path 11 of measuring light
Optical fiber gas sensor for measuring gas concentration in oil.

Description

[Detailed description of the device]

[0001]

[Industrial application]

 The present invention relates to an optical fiber gas sensor for measuring gas concentration in oil.

[0002]

[Prior Art]

 Insulating oils used in OF cables and oil-in-water transformers generate combustible gases such as methane gas and acetylene gas during use due to thermal deterioration and high-voltage discharge. By measuring the amount of flammable gas, it is possible to monitor the state of insulation deterioration in cables and equipment, so it is necessary to measure the concentration of flammable gas in the insulating oil used.

For example, in the case of an OF cable, after collecting a large amount of insulating oil from the OF cable at the installation site of the OF cable, the collected oil is transported to another place where it can be analyzed, and then the collected oil is collected by a vacuum suction pump. The concentration of combustible gas in insulating oil has been measured by extracting the contained gas from the gas and separating and quantifying the extracted gas with a gas chromatograph. However, this method has a problem in that the work up to the concentration measurement is extremely complicated and requires a long time and a great deal of effort.

On the other hand, as a gas detection sensor for methane gas or the like, a remotely operable gas sensor using an optical fiber has recently been proposed. In this gas sensor, as shown in FIG. 4, light from a light source 13 arranged at a distant place is transmitted through an optical fiber 14, and the light is transmitted through a gas detection cell 15 into which a gas to be measured is introduced. Let it pass. In the gas detection cell 15, the light having the absorption wavelength is absorbed by the gas to be measured.

A beam splitter 16 that transmits only the light having the absorption wavelength of the gas to be measured by the interference filters 21 and 21 ′ of the interference system 20, and the light that has passed through the gas detection cell 15 is not absorbed by the gas to be measured. The light beams pass through the beam splitter 17 that transmits only the wavelength light, respectively. Then, the detector 18 detects the intensity difference between the two, and the detected signal is amplified by the amplifier 19, and the amplified signal is taken out by the computer 22 or recorded by a printer or a recorder.

In this case, according to Lambert-Beer's law, since the absorbance due to the gas to be measured and the concentration of the gas to be measured are in a proportional relationship, the above-mentioned value obtained by calibrating the bull of the optical signal due to mechanical or vibration is obtained. The measured gas concentration can be measured from the detection signal.

[0007]

[Problems to be solved by the device]

 By the way, when measuring the combustible gas concentration of insulating oil such as OF cable and transformer in oil, if the combustible gas extracted from the insulating oil is introduced into the gas detection cell as described above, it can be operated remotely. It becomes possible to measure the gas concentration in oil. In this case, if the extraction of the flammable gas is performed by vacuum suction from the insulating oil as in the conventional case, only the detection means is changed from the conventional gas chromatography device to the above-mentioned gas sensor, and the conventional method has the problem. It is hard to say that we have solved

The present invention is a sensor for measuring a gas concentration in oil by using a gas sensor that can be remotely controlled by an optical fiber as described above. The sensor itself can separate a combustible gas from insulating oil. Therefore, it is an object of the present invention to provide an optical fiber gas sensor for measuring the gas concentration in oil, which can be installed in the installation site such as OF cable and transformer in oil, etc., because the whole is very compact.

[0009]

[Means for Solving the Problems]

 In order to achieve the above-mentioned object, the present invention provides a double tube structure comprising an outer cylinder and an inner cylinder concentrically arranged in the outer cylinder and provided with a gas-liquid separation membrane, The gas-liquid separating cylinder body portion A, which is formed by sealing both ends of the double pipe with annular end plates to form an annular closed space in which the gas for measuring gas concentration flows, is formed between the outer cylinder and the inner cylinder. A double tube structure comprising a tube and a porous inner tube concentrically arranged in the outer tube, wherein one end of the double tube is sealed with an annular end plate to form an inner tube with the outer tube. An optical path of gas concentration measuring light sent from an optical fiber is provided in the inner cylinder of the sensor outer cylinder part of the gas detection cell enclosed in the annular space of the sensor outer cylinder part B in which an annular space with one end opening is formed between the cylinders. An optical fiber gas sensor for measuring a gas concentration in oil is provided.

[0010]

[Action]

 When the insulating oil containing the gas to be measured is introduced into the annular closed space of the gas-liquid separation cylinder portion A, the gas to be measured passes through the gas-liquid separation film and reaches the inner cylinder of the sensor outer cylinder portion B. Since this inner cylinder is porous, the gas to be measured reaches the optical path (inside the inner cylinder) of the measurement light transmitted through the inner cylinder through the optical fiber. Then, here, the measured gas concentration is measured by the measurement light.

Extracting the gas to be measured from the insulating oil is performed by the gas-liquid separation film of the gas-liquid separation cylinder A, so that a conventional vacuum suction device is unnecessary and the sensor is very compact. Can be made into any shape.

[0012]

【Example】

 Hereinafter, embodiments of the gas sensor of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a partially cutaway side view of a gas detection cell, which is an essential part of the gas sensor of the present invention. The gas detection cell has a structure in which a gas-liquid separation cylinder portion A described later is enclosed in an annular space 10 described later of the sensor outer cylinder portion B.

First, FIG. 2 is a perspective view showing an example of a gas-liquid separation cylinder portion A which constitutes a gas detection cell in the gas sensor of the present invention. In FIG. 1, the gas-liquid separating cylinder portion A has a double pipe structure including an outer cylinder 1 and an inner cylinder 2 concentrically arranged in the outer cylinder 1. Both ends of this double pipe structure are sealed by annular end plates 3a and 3b, and an annular closed space 4 is provided between the outer cylinder 1 and the inner cylinder 2 in the longitudinal direction of the cylindrical body portion A. An inner diameter portion of the inner cylinder 2 formed over the entire length is a hollow portion 5 penetrating in the longitudinal direction of the gas-liquid separating cylinder portion A.

Then, for example, two copper pipes 6a and 6b are connected to the one annular end plate 3b, and oil for gas concentration measurement flows into the annular closed space 4 from the copper pipes 6a (or 6b). Thus, the annular closed space 4 is filled and can flow out from the copper pipe 6a (or 6b). Here, the outer cylinder 1 and the end plates 3a and 3b are made of, for example, a metal plate such as a copper plate, a brass plate, or a stainless steel plate, or a resin plate such as an acrylic resin plate or an epoxy resin plate.

The inner cylinder 2 is composed of a gas-liquid separation membrane. Considering the reinforcing effect and the ease of manufacturing, the inner cylinder 2 is formed of a mesh material such as a wire mesh, and the inner surface of the inner cylinder 2 is covered with a gas. It is preferable that the liquid separation membrane is attached. The gas-liquid separation membrane used is made of a material having excellent oil resistance, and the gas that has dissolved in it from the oil that has flowed into the annular closed space 4 (for example, hydrogen, carbon dioxide, carbon monoxide, methane, ethane, propane). , Ethylene, propylene, acetylene, etc.) but not oil.

Examples of such a gas-liquid separation membrane include a film containing a fluororesin as a main component, a cellulose-based film, a polyvinylidene chloride-based film, and the like. A film whose main component is a fluororesin of about 50 to 500 μm is suitable. FIG. 3 is a perspective view showing an example of the sensor outer cylinder portion B of the gas detection cell in the gas sensor of the present invention.

In FIG. 3, the sensor outer cylinder portion B has a double pipe structure of an outer cylinder 7 and an inner cylinder 8 concentrically arranged in the outer cylinder 7, and one of the double tubes is The end portion of is closed by an annular end plate 9. Therefore, an annular space 10 having one end opened is formed between the outer cylinder 7 and the inner cylinder 8, and the inner diameter portion of the inner cylinder 8 is a hollow portion 11 penetrating in the longitudinal direction of the sensor outer cylinder portion B. There is. Then, this hollow portion 11 serves as an optical path of light for measuring gas concentration.

Here, both the outer cylinder 7 and the annular end plate 9 are made of the same material as the outer cylinder 1 and the end plates 3 a, 3 b of the gas-liquid separating cylinder portion A. The inner cylinder 8 is made of, for example, a porous material such as a metal wire mesh or a ceramic porous plate, and has a through hole of about 100 μm to 1 mm formed throughout. The gas detection cell in the gas sensor of the present invention is such that the gas-liquid separating cylinder portion A is inserted into the annular space 10 from one end opening portion of the annular space 10 of the sensor outer cylinder portion B described above, and the gas liquid separation is performed at the one end opening portion. It is manufactured by sealing the oil inflow / outflow pipe side of the separation cylinder portion A and enclosing the gas-liquid separation cylinder A in the sensor outer cylinder portion B 1.

Next, the operation will be described. Oil 12 for gas concentration measurement is introduced from the copper pipe 6a of the gas detection cell to fill the annular closed space 4 of the gas-liquid separation cylinder portion A. The gas dissolved in oil is separated by the gas-liquid separation film forming the inner cylinder 2 of the gas-liquid separation cylinder portion A and moves to the inner cylinder 8 side of the sensor outer cylinder portion B.

Then, the separated gas passes through the porous inner cylinder 8 and fills the hollow part of the sensor outer cylinder part B, that is, the optical path 11 of the gas concentration measuring light sent from the optical fiber. Since light for measuring gas concentration is introduced into the optical path 11 by an optical fiber (not shown) as shown by an arrow, the gas concentration in oil can be measured from its absorbance. For example, the gas-liquid separation cylinder A, the inner cylinder of the sensor outer cylinder B, and the end plates are all made of FRP resin, the gas-liquid separation film is a fluororesin film having a thickness of 100 μm, and the inner cylinder of the sensor outer cylinder is As a metal wire mesh with an average pore diameter of 150 μm, the overall outer diameter is 50 mm. When a gas detection cell with a total length of 300 mm was manufactured and the acetylene concentration in the insulating oil was measured, it was possible to detect up to a sensitivity of 10 ppm.

[0021]

[Effect of the device]

 As is apparent from the above description, the optical fiber gas sensor for measuring gas concentration in oil of the present invention comprises an outer cylinder and an inner cylinder concentrically arranged in the outer cylinder and having a gas-liquid separation membrane. A gas-liquid separation cylinder having a double pipe structure, in which both ends of the double pipe are sealed with annular end plates to form an annular closed space into which the gas for measuring gas concentration flows between an outer cylinder and an inner cylinder. The body A has a double tube structure including an outer cylinder and a porous inner cylinder concentrically arranged in the outer cylinder, and one end of the double tube is sealed with an annular end plate. Then, the inside of the inner cylinder of the sensor outer cylinder part of the gas detection cell enclosed in the annular space of the sensor outer cylinder part B having an annular space with one end opening formed between the outer cylinder and the inner cylinder is sent from the optical fiber. It is characterized in that it is used as the optical path of the gas concentration measurement light that is used, so there is no need to provide a separate device for extracting the gas in the oil. At the same time the body becomes compact, it is possible to measure the gas concentration by measuring light transmitted me by remotely to the optical fiber, its practical value is great.

[Brief description of drawings]

FIG. 1 is a partial perspective view showing an example of a gas detection cell which is a main part of a gas sensor of the present invention.

FIG. 2 is a perspective view showing an example of a gas-liquid separating cylinder portion.

FIG. 3 is a perspective view showing an example of a sensor outer cylinder portion.

FIG. 4 is a schematic view showing a gas concentration detection system using an optical fiber.

[Explanation of symbols]

 A gas-liquid separation cylinder part B sensor outer cylinder part 1 outer cylinder of gas-liquid separation cylinder part A 2 inner cylinder of gas-liquid separation cylinder part A 3a, 3b annular end plate of gas-liquid separation cylinder part 4 gas Sealed annular space of liquid separation cylinder portion A 5 Hollow portion of gas-liquid separation cylinder portion A 6a, 6b Copper pipe 7 Outer cylinder of sensor outer cylinder portion 8 Inner cylinder of sensor outer cylinder portion 9 Sensor outer cylinder portion B End plate of 10 annular space of sensor outer cylinder B 11 optical path (hollow part of sensor outer cylinder B) 12 oil

Claims (1)

[Scope of utility model registration request] 1. A double pipe structure comprising an outer cylinder and an inner cylinder concentrically arranged in the outer cylinder and provided with a gas-liquid separation membrane, wherein both ends of the double tube are annular ends. A gas-liquid separating cylinder portion A, which is sealed with a plate and forms an annular closed space into which the gas concentration measuring oil flows between the outer cylinder and the inner cylinder, is concentrically arranged in the outer cylinder and the outer cylinder. A double-tube structure composed of a porous inner cylinder and a closed inner end formed between the outer cylinder and the inner cylinder by sealing one end of the double-tube with an annular end plate. For gas concentration measurement in oil, characterized in that the inside of the sensor outer cylinder of the gas detection cell enclosed in the annular space of the sensor outer cylinder B is used as an optical path for gas concentration measuring light sent from an optical fiber. Fiber optic gas sensor.