JP2006010546A - Gas detector and fuel cell system equipped therewith - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gas detector preventing water from staying around a gas detection element to further enhance its reliability, and to provide a fuel cell system equipped therewith. <P>SOLUTION: This gas detector is equipped with a gas detection chamber 15 connected to an inspecting object gas passage 14 for allowing an inspecting object gas to flow therethrough. The detector is equipped with the gas detection element 1 for detecting the object gas introduced into the detection chamber 15 and opening-to-air devices 16 and 17 provided in the vicinity of the detection element 1 for opening the detection chamber 15 to air. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention includes a gas detection device that includes a gas detection chamber connected to an inspection target gas flow path through which an inspection target gas flows, and includes a gas detection element that detects the inspection target gas introduced into the gas detection chamber, and The present invention relates to a fuel cell system including the same.

In recent years, in a system having a fuel cell including an anode and a cathode, a gas sensor that detects hydrogen is provided in a cathode side pipe and has a configuration that detects whether hydrogen is mixed in the cathode side pipe. Are known.
By the way, the off-gas on the cathode side of the fuel cell contains a lot of moisture (for example, generated water and humidified water) due to its nature, so the gas sensor is exposed to moisture-containing gas and measures against condensation on the gas sensor. It is necessary to do.

As a technique for taking measures against condensation on the gas sensor, a technique for covering the gas detection section with a cover (see Patent Document 1) and a technique for providing a heater for heating the gas to be detected adjacent to the upstream side of the gas sensor (see Patent Document 2). Has been proposed.
Japanese Patent Laid-Open No. 9-5279 JP 2004-69436 A

  However, even if condensation measures are taken in the conventional technology, moisture still remains around the gas detection element and depends on the performance of the heater and cover. It is desirable to do.

  Accordingly, an object of the present invention is to provide a gas detection device and a fuel cell system including the gas detection device that can prevent moisture from staying around the gas detection element and can further improve reliability.

  The invention according to claim 1 is a gas detection chamber (for example, implementation) connected to an inspection target gas flow path (for example, the exhaust pipe 14 in the embodiment) through which the inspection target gas (for example, hydrogen in the embodiment) flows. And a gas detection element (for example, gas sensor 1 in the embodiment) for detecting the inspection target gas introduced into the gas detection chamber, and provided in the vicinity of the gas detection element. An air release device that opens the gas detection chamber to the atmosphere (for example, an air release path 16, an open valve 17, and a discharge fan 18 in the embodiment) is provided.

  According to this invention, when the inspection target gas is introduced into the gas detection chamber, the inspection target gas introduced into the gas detection chamber by opening the gas detection chamber to the atmosphere with the atmosphere release device. Can be released into the atmosphere. Therefore, even when moisture is contained in the inspection target gas, it is possible to cause the moisture to flow out into the atmosphere together with the inspection target gas, and to prevent moisture from staying in the gas detection chamber. it can. Thereby, reliability can further be improved.

  The invention according to claim 2 includes a gas detection chamber connected to an inspection target gas flow path through which an inspection target gas flows, and a gas detection element that detects the inspection target gas introduced into the gas detection chamber; An atmosphere introduction device (for example, the atmosphere introduction path 19 and the introduction fan 20 in the embodiment) provided in the vicinity of the gas detection element and introducing the atmosphere into the gas detection chamber is provided.

  According to the present invention, the inspection target gas can be caused to flow out from the gas detection chamber by introducing the atmosphere into the gas detection chamber by the atmosphere introduction device. Therefore, even when water is contained in the inspection target gas, the water can flow out of the gas detection chamber together with the inspection target gas, and moisture is prevented from staying in the gas detection chamber. be able to. Thereby, reliability can further be improved. In addition, when the atmosphere is introduced into the gas detection chamber, the gas to be inspected can be discharged from the gas detection chamber. At this time, the zero point correction of the gas detection element is performed, thereby detecting the gas. The detection accuracy of the element can be kept high. In this way, it is possible to determine that there is no inspection target gas around the gas detection element without performing the process of measuring the concentration of the inspection target gas. Therefore, it is not necessary to provide a device for measuring the concentration of the gas to be inspected, thereby preventing an increase in cost.

  The invention according to claim 3 is a fuel comprising: a fuel cell that generates power by a chemical reaction by supplying a hydrogen-containing gas and an oxygen-containing gas; and an off-gas flow passage through which off-gas discharged from the fuel cell flows. A battery system comprising the gas detection device according to claim 1 or 2, wherein the gas detection chamber is connected to the off-gas flow passage, and the off-gas is an inspection target gas.

  According to the present invention, in a fuel cell that generates moisture during power generation and discharges the moisture together with off-gas, a large amount of moisture exists in the gas to be inspected, so it is desirable to take measures against condensation on the gas detection element. However, since the reliability of the gas detection device can be improved by providing the gas detection device according to claim 1 or 2, the reliability of the entire system can be further improved.

  According to the first aspect of the present invention, even when the gas to be inspected contains moisture, the water can be discharged into the atmosphere together with the gas to be inspected. Since retention can be prevented, reliability can be further improved.

According to the second aspect of the present invention, even when water is contained in the inspection target gas, the water can be allowed to flow out of the gas detection chamber together with the inspection target gas. Since the moisture can be prevented from staying, the reliability can be further improved. In addition, it is possible to maintain high detection accuracy of the gas detection element while suppressing an increase in cost.
According to the invention which concerns on Claim 3, since the reliability of a gas detection apparatus can be improved, the reliability as the whole system can be improved further.

Hereinafter, a gas detection device and a fuel cell system including the same according to embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram of a fuel cell system according to an embodiment of the present invention.
The fuel cell 5 is composed of a stack formed by stacking a plurality of cells formed by sandwiching a solid polymer electrolyte membrane made of, for example, a solid polymer ion exchange membrane between an anode and a cathode from both sides. When air containing oxygen as an oxidant is supplied to the cathode, hydrogen ions generated by a catalytic reaction at the anode move to the cathode through the solid polymer electrolyte membrane, and electrochemical reaction with oxygen at the cathode To generate electricity and produce water. Since part of the generated water generated on the cathode side is diffused back to the anode side through the solid polymer electrolyte membrane, the generated water is also present on the anode side.

  The air is pressurized to a predetermined pressure by the compressor 12 and supplied to the cathode of the fuel cell 5 through the air supply passage 7. After the air supplied to the fuel cell 5 is used for power generation, it is discharged from the fuel cell 5 together with the produced water on the cathode side into the air discharge passage 9 and introduced into the purge hydrogen dilution device 13.

On the other hand, hydrogen supplied from the hydrogen tank 11 is supplied to the anode of the fuel cell 5 through the hydrogen supply channel 6. Then, the hydrogen discharged from the fuel cell 5 is discharged to the hydrogen discharge flow path 8. The hydrogen discharge flow path 8 is connected to a purge hydrogen dilution device 13.
Hydrogen discharged from the fuel cell 1 is introduced into the purge hydrogen dilution device 13 via the hydrogen discharge flow path 8. Then, the hydrogen is diluted by the air introduced into the purge hydrogen dilution device 13 via the air discharge flow path 9, and the diluted hydrogen is discharged from the discharge pipe 14 as an exhaust gas.

FIG. 2 is a cross-sectional view of a main part of the gas detection device according to the first embodiment. As shown in the figure, a sub pipe 15 is connected to the discharge pipe 14, and the gas sensor 1 is provided in the sub pipe 15. The gas sensor 1 is for detecting the hydrogen concentration of the exhaust gas flowing through the exhaust pipe 14, and the output signal of the gas sensor 1 is input to the control device 2.
For example, the control device 2 determines whether or not an abnormal state of the fuel cell 5 has occurred according to a comparison result between the detection signal output from the gas sensor 1 and a predetermined determination threshold, and is in an abnormal state. When it is determined, an alarm or the like is output by an alarm device (not shown).

For example, as shown in FIG. 2, the gas sensor 1 includes a case 21 having a rectangular shape that is long in the longitudinal direction of the discharge pipe 14 extending in the horizontal direction, that is, in the horizontal direction. The case 21 is made of, for example, polyphenylene sulfide, and includes flange portions 22 at both ends in the longitudinal direction.
Further, a cylindrical portion 26 is formed on the end surface in the thickness direction of the case 21, the inside of the cylindrical portion 26 is formed as a gas detection portion 27, and an inner side surface of the gas detection portion 27 is flanged inward. A portion 28 is formed, and an inner peripheral portion of the flange portion 28 is formed as an opening as a gas introduction portion 29.

  A circuit board 30 sealed with resin is provided in the case 21, and the detection element 31 and the temperature compensation element 32 disposed inside the cylindrical portion 26 are connected to the circuit board 30. Each element 31, 32 is connected to the circuit board 30 by a plurality of, for example, four energizing stays 33 and a platinum wire 33 a as a lead wire, and a base 34 disposed on the bottom surface side of the gas detection unit 27. At a position separated from the metal base material 38 by a predetermined distance in the thickness direction of the gas sensor 1, the gas sensor 1 is disposed so as to form a pair with a predetermined interval. Further, a sealing material 35 is attached to the outer peripheral surface of the cylindrical portion 26, and the sealing material 35 is in close contact with the inner peripheral wall of the through hole 15 a of the sub pipe 15 to ensure airtightness.

The detection element 31 is a catalytic combustion type element, and the surface of the coil of a metal wire containing platinum or the like having a high temperature coefficient for electric resistance is a catalyst made of a noble metal or the like that is active against hydrogen to be detected gas. It is formed by being covered with a carrier such as alumina to be carried.
The temperature compensation element 32 is inactive with respect to the gas to be detected. For example, the surface of the coil equivalent to the detection element 31 is covered with a carrier such as alumina.

  And the detection element 31 which became high temperature by the heat_generation | fever of the combustion reaction which arises when hydrogen which is to-be-detected gas contacts the catalyst of the detection element 31, and the combustion reaction by a to-be-detected gas does not generate | occur | produce, By utilizing the fact that a difference in electrical resistance value occurs between the temperature compensation element 32 and the temperature compensation element 32, it is possible to detect the hydrogen concentration by offsetting the change in the electrical resistance value due to the ambient temperature.

A heater 36 having a substantially rectangular plate shape is disposed in the gas detection unit 27. The heater 36 is composed of a resistor or the like, and heats the inside of the gas detector 27 and the elements 31 and 32 when energized by the circuit board 30.
In addition, a water repellent filter 40 and a filter 41 are disposed in the gas detection unit 27 in order to reduce environmental influences, for example, the degree of influence of moisture and detected gas.

  The sub-pipe 15 is connected to an air release path 16 that is provided in the vicinity of the gas sensor 1 and opens the sub-pipe 15 to the atmosphere. An opening valve 17 is provided at the tip of the atmosphere opening path 16. By leaving the release valve 17 fully open, the exhaust gas in the sub-pipe 15 can flow out to the outside.

  Therefore, when exhaust gas (diluted hydrogen off-gas) flowing through the exhaust pipe 14 is being introduced into the sub-pipe 15, the open valve 17 is fully opened to open to the atmosphere, thereby introducing it into the sub-pipe 15. Exhaust gas discharged to the atmosphere. Therefore, even when the exhaust gas introduced into the sub-pipe 15 contains moisture, the moisture can be discharged into the atmosphere together with the exhaust gas. Therefore, it is possible to prevent moisture from staying in the auxiliary pipe 15. Thereby, the reliability of the gas sensor 1 can further be improved.

  FIG. 3 is a cross-sectional view of the gas detection device according to the second embodiment. As shown in the figure, the present embodiment is different from the above-described embodiment in that a discharge fan 18 is mounted in the atmosphere opening path 16. In this way, when the exhaust gas (diluted hydrogen off-gas) flowing through the exhaust pipe 14 is being introduced into the sub pipe 15, the exhaust fan 18 is operated, so that the sub pipe 15 can be operated. The flow rate of the exhaust gas discharged can be increased. Therefore, it is possible to more effectively prevent moisture from staying in the auxiliary pipe 15. Thereby, the reliability of the gas sensor 1 can further be improved.

  FIG. 4 is a cross-sectional view of a gas detection device according to the third embodiment. As shown in the figure, in the present embodiment, an atmospheric introduction path 19 is connected to the sub-pipe 15, and an introduction fan 20 is mounted in the atmospheric introduction path 19. Further, a shutter valve 14 a that can allow or block the flow of exhaust gas is provided in the exhaust pipe 14. These points are different from the above-described embodiment.

  In this way, the introduction fan 20 is operated to introduce the atmosphere into the auxiliary pipe 15 via the atmosphere introduction path 19, so that the exhaust gas flows out from the auxiliary pipe 15 into the discharge pipe 14 by the atmosphere. Can be made. Therefore, even when the exhaust gas contains moisture, it is possible to cause the moisture to flow out of the auxiliary pipe 15 together with the exhaust gas, and to prevent moisture from staying in the auxiliary pipe 15. Can do. Thereby, the reliability of the gas sensor 1 can further be improved.

  In addition, when the atmosphere is introduced into the sub-pipe 15, exhaust gas can be discharged from the sub-pipe 15. At this time, by correcting the zero point of the gas sensor 1, High detection accuracy can be maintained. In this way, since it can be determined that there is no hydrogen around the gas sensor 1 without performing the process of measuring the hydrogen concentration in the exhaust gas, It is not necessary to provide a device for measuring the concentration of the liquid, and an increase in cost can be prevented.

  At this time, if the shutter valve 14a in the discharge pipe 14 is operated to close the flow path in the discharge pipe 14, the exhaust gas flowing out from the sub pipe 15 is quickly moved to the downstream side of the shutter valve 14a in the discharge pipe 14. It is preferable in that it can be guided to.

  Of course, the contents of the present invention are not limited to the above-described embodiments. For example, in the embodiment, the case where the inspection target gas is hydrogen has been described. However, the present invention is not limited to this, and other gases (such as methanol) may be used. In the embodiment, the case where the gas detection device is applied to the fuel cell system has been described. However, the gas detection device can also be applied to other systems. Further, in the embodiment, as the gas detection element, a gas contact combustion type gas sensor, that is, a difference in electric resistance between the detection element and the temperature compensation element using heat that is burned when the detection target gas contacts the catalyst. The gas sensor for detecting the gas concentration of the detection target gas is described above, but is not limited thereto. For example, a semiconductor gas sensor that detects the gas concentration of the detection target gas by changing an element resistance value that occurs when the detection target gas comes into contact with and leaves oxygen on the surface of the detection element may be used.

It is a whole block diagram of the fuel cell system which has a gas detection apparatus in the 1st to 3rd embodiment of this invention. It is sectional drawing of the gas detection apparatus in 1st Embodiment. It is sectional drawing of the gas detection apparatus in 2nd Embodiment. It is sectional drawing of the gas detection apparatus in 3rd Embodiment.

Explanation of symbols

1. Gas sensor (gas detection element)
14 ... Drain pipe (inspection gas flow path)
15 ... Sub piping (gas detection chamber)
16 ... Air release path (atmosphere release device)
17 ... Open valve (atmospheric release device)
18 ... Discharge fan (atmospheric release device)
19 ... Air introduction path (atmosphere introduction device)
20 ... Introduction fan (atmospheric introduction device)

Claims (3)

A gas detection element that includes a gas detection chamber connected to the inspection target gas flow path through which the inspection target gas flows, and that detects the inspection target gas introduced into the gas detection chamber;
A gas detection device comprising: an air release device that is provided in the vicinity of the gas detection element and opens the gas detection chamber to the atmosphere. A gas detection element that includes a gas detection chamber connected to the inspection target gas flow path through which the inspection target gas flows, and that detects the inspection target gas introduced into the gas detection chamber;
A gas detection device comprising: an air introduction device that is provided in the vicinity of the gas detection element and introduces air into the gas detection chamber. A fuel cell that generates electricity by a chemical reaction by supplying a hydrogen-containing gas and an oxygen-containing gas;
An off-gas flow passage through which off-gas discharged from the fuel cell circulates, and a fuel cell system comprising:
A gas detection device according to claim 1 or 2, comprising:
A fuel cell system, wherein the gas detection chamber is connected to the off-gas flow passage, and the off-gas is an inspection target gas.

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