JP2009123471A - Fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To appropriately suppress breakage of piping or the like in a gas supply passage in a fuel cell system. <P>SOLUTION: A fuel cell system 10 includes: a fuel gas tank 20; a gas supply passage 24 for supplying gas from the fuel gas tank 20 arranged on the upstream side to a fuel cell stack 12 arranged on the downstream side; an upstream-side pressure reducing valve 22 reducing the pressure of high pressure gas; a downstream-side pressure reducing valve 28 more reducing the pressure of gas whose pressure is reduced with the upstream-side pressure reducing valve 22; and a relief valve 30 arranged between the upstream-side pressure reducing valve 22 and the downstream-side pressure reducing valve 28 in the gas supply passage 24, and opening when the pressure in the gas supply passage 24 in the arranged position reached the prescribed threshold value. The relief valve 30 is arranged in the position where the pressure of the gas supply passage 24 in the arranged position does not exceed the withstand pressure value of a passage element on the downstream side than the arranged position. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a fuel cell system, and more particularly to a fuel cell system in which a relief valve is provided in a flow path for supplying gas to a fuel cell stack.

  In a fuel cell system, when power generation is performed, fuel gas and oxidizing gas are supplied to the electrodes of the fuel cell stack. For example, in a system for supplying fuel gas to the fuel cell stack after appropriately reducing the pressure of the fuel gas from the high-pressure fuel gas supply source, a countermeasure when a problem occurs in the mechanism related to the pressure adjustment of the fuel gas. is required. Therefore, in Patent Document 1, a fuel gas flow path for supplying fuel gas to the fuel cell and a fuel gas flow path are provided in the fuel gas flow path, and when the fuel gas in the fuel gas flow path exceeds a predetermined pressure, the fuel gas is externally supplied. In a fuel cell system having a relief valve that discharges to the outside, an external discharge passage provided on the gas release side of the relief valve and a concentration of fuel gas released from the relief valve provided in the external discharge passage What is provided with the gas processing apparatus which performs is disclosed.

JP 2005-332648 A

  By using the configuration of the above-mentioned Patent Document 1, the pressure in the fuel gas channel can be lowered. However, as in Patent Document 1, if a relief valve is simply provided in the fuel gas channel, the pressure in the fuel gas channel increases due to some factor, and the surrounding fuel gas channel in which the relief valve is provided Even if the pressure of the fuel reaches a predetermined pressure or higher and the relief valve starts to open, depending on the relationship between the pressure decrease rate due to the release of the fuel gas and the above-mentioned pressure increase rate, the fuel gas There is a possibility of exceeding the pressure at which piping in the flow path is damaged.

  An object of the present invention is to provide a fuel cell system that can more appropriately suppress breakage of piping or the like of a gas supply channel.

  In the fuel cell system according to the present invention, a high-pressure gas tank filled with a high-pressure gas, and a gas supply channel for supplying gas from the high-pressure gas tank arranged on the upstream side to the fuel cell stack arranged on the downstream side And an upstream pressure reducing valve provided on the upstream side of the gas supply flow path to depressurize the high-pressure gas, and a pressure reducing pressure further reduced by the upstream pressure reducing valve provided on the downstream side of the gas supply flow path. The downstream pressure reducing valve is disposed between the upstream pressure reducing valve and the downstream pressure reducing valve in the gas supply flow path, and the pressure of the gas supply flow path at the arrangement position is equal to or higher than a predetermined threshold value. A relief valve that is sometimes opened, and the relief valve is arranged at a position where the pressure of the gas supply flow path at the arrangement position does not exceed the pressure resistance value of the flow path element downstream from the arrangement position. Is the fact characterized.

  In addition, the fuel cell system according to the present invention includes a volume portion that is provided between the relief valve and the downstream pressure reducing valve in the gas supply channel and has a larger channel diameter than the channel diameter of the gas supply channel. The relief valve is preferably opened when the pressure between the upstream pressure reducing valve and the volume part is equal to or higher than a predetermined threshold in the gas supply flow path.

  In the fuel cell system according to the present invention, it is preferable that the upstream pressure reducing valve and the relief valve have an integral structure.

  In the fuel cell system according to the present invention, it is preferable that the diameter of the gas supply path is larger than the diameter of the relief valve.

  With the above configuration, the fuel cell system includes the relief valve disposed at a position where the pressure of the gas supply flow path at the position where the relief valve is disposed does not exceed the pressure resistance value of the flow path element on the downstream side of the disposed position. Therefore, it is possible to more appropriately suppress damage to the piping of the gas supply flow path.

  Embodiments according to the present invention will be described below in detail with reference to the drawings. Hereinafter, the high-pressure gas will be described as a fuel gas (hydrogen gas), but of course, the high-pressure gas is not limited to the fuel gas and may be, for example, an oxidizing gas.

  FIG. 1 is a diagram showing the configuration of the fuel cell system 10. The fuel cell system 10 includes a fuel cell stack 12 in which a plurality of fuel cells are stacked, each element for supplying fuel gas disposed on the anode side of the fuel cell stack 12, and an oxidizing gas supply disposed on the cathode side. It is comprised including each element of.

  The fuel cell stack 12 is an assembled battery by laminating a plurality of single cells sandwiched by arranging separators on both outer sides of an MEA (Membrane Electrode Assembly) in which catalyst electrode layers are arranged on both sides of an electrolyte membrane. . The fuel cell stack 12 supplies a fuel gas such as hydrogen to the anode side, supplies an oxidizing gas containing oxygen, for example, air, to the cathode side, generates power by an electrochemical reaction through the electrolyte membrane, and takes out necessary power. It has a function.

  The oxidant gas source 40 on the cathode side can actually use the atmosphere. The atmosphere as the oxidizing gas source 40 is supplied to an air compressor (ACP) through a filter. A humidifier is provided in the flow channel on the cathode side, and the humidifier has a function of appropriately moistening the oxidizing gas and efficiently performing the fuel cell reaction in the fuel cell stack 12. The oxidizing gas appropriately moistened by the humidifier is supplied to the cathode side inlet of the fuel cell stack 12 and discharged from the cathode side outlet.

  The cathode-side flow path is provided with an inlet-side air shut valve and an outlet-side air shut valve. The inlet side air shut valve and the outlet side air shut valve are each connected to a humidifier. The inlet side air shut valve and the outlet side air shut valve are normally open. For example, it has a pipe line in which a movable element such as a piston moves back and forth inside, and the inlet side of the pipe line is connected to the flow path on the humidifier side, and the outlet side of the pipe line is the flow path on the fuel cell stack 12 side. Connected to. When the internal pressure of the pressure chamber is changed to allow the mover to enter the pipe, the pipe inside the inlet side air shut valve is closed, so that the flow of the oxidizing gas is blocked. Thus, the internal pressure of the pressure chamber can be controlled to move the mover forward and backward, and the flow of the oxidizing gas in the flow path can be shut off, that is, shut down as necessary.

  In addition, a pressure regulating valve is provided in the flow channel on the cathode side. Although the pressure regulating valve is also called a back pressure valve, it has a function of adjusting the gas pressure at the cathode side outlet and adjusting the flow rate of the oxidizing gas to the fuel cell stack 12. Since the output port of the pressure regulating valve is connected to the humidifier, the gas exiting the pressure regulating valve enters the diluter 50 after supplying water vapor to the humidifier, and is then discharged to the outside.

  The diluter 50 collects hydrogen mixed with impurity gas and moisture from the anode side exhaust valve 38, which will be described later, and water mixed with moisture leaking from the cathode side through the MEA, and discharges it to the outside as an appropriate hydrogen concentration. This is a buffer container.

  The anode-side fuel gas tank 20 is a high-pressure gas tank that is a hydrogen gas source and supplies hydrogen as a fuel gas. Since the hydrogen gas has a high pressure, it is adjusted to an appropriate pressure and flow rate by an upstream pressure reducing valve 22 and a downstream pressure reducing valve 28 provided in a gas supply flow path 24 that communicates the fuel gas tank 20 and the fuel cell stack 12. It is supplied to the fuel cell stack 12.

  The upstream pressure reducing valve 22 is a valve that adjusts the pressure in the gas supply passage 24. The upstream pressure reducing valve 22 is provided on the downstream side of the fuel gas tank 20, and depressurizes the hydrogen gas (for example, 70 MPa) output from the fuel gas tank 20 to a predetermined pressure (for example, 3 MPa).

  The relief valve 30 is disposed between the upstream pressure reducing valve 22 and the downstream pressure reducing valve 28 in the gas supply flow path 24, and the pressure of the gas supply flow path at the position of the relief valve 30 is a predetermined threshold (for example, 4 MPa). When the pressure reaches the value, the valve is opened to release the gas in the gas supply channel 24 to the outside, and the pressure in the gas supply channel 24 is lowered. The relief valve 30 is disposed downstream of the upstream pressure reducing valve 22 in the gas supply flow path 24 so that the pipe line resistance between the upstream pressure reducing valve 22 and the relief valve 30 is minimized. The Further, the diameter of the relief valve 30 is set to allow a predetermined flow rate to flow, but is set to be equal to or smaller than the diameter of the gas supply flow path 24.

  The volume portion 26 is a container having a diameter larger than the diameter of the gas supply flow path 24 and has a function of suppressing the pressure increase rate of the gas supply flow path 24. The volume portion 26 is disposed between the upstream side pressure reducing valve 22 and the downstream side pressure reducing valve 28 in the gas supply flow path 24 and downstream of the relief valve 30.

  The downstream pressure reducing valve 28 is a valve that adjusts the pressure in the gas supply flow path 24, similarly to the upstream pressure reducing valve 22. The downstream pressure reducing valve 28 is provided in the gas supply flow path 24 on the downstream side of the relief valve 30 and the volume portion 26, and hydrogen gas decompressed by the upstream pressure reducing valve 22 is further supplied to a predetermined pressure (for example, 0.4 MPa). ) Until reduced pressure.

  The fuel gas shut valve 32 is a valve that opens and closes the gas supply passage 24. The fuel gas shut valve 32 is provided on the downstream side of the downstream pressure reducing valve 28 and can supply hydrogen gas to the fuel cell stack 12 or can stop the supply.

  The shunt 36 connected to the anode side outlet of the fuel cell stack 12 is used to flow to the diluter 50 through the exhaust valve 38 when the impurity gas concentration of the exhaust gas from the anode side outlet increases. Further, the circulation booster 34 provided between the flow divider 36 and the anode side inlet further increases the hydrogen partial pressure of the gas returning from the anode side outlet and returns it to the anode side inlet for reuse. It has a hydrogen pump.

  FIG. 2 is a diagram illustrating the pressure increase value of the gas supply passage 24 when the horizontal axis represents time and the vertical axis represents pressure, and the upstream pressure reducing valve 22 malfunctions. A pressure characteristic curve 61 shows a state of pressure increase at the pressure monitoring point 14 in the gas supply flow path 24. The pressure characteristic curve 62 shows a state of pressure increase at the pressure monitoring point 16. Here, when the time of pressure increase at the pressure monitoring point 14 is compared with the time of pressure increase at the pressure monitoring point 16, the pressure monitoring point 14 has a smaller pipe resistance or the like than the pressure monitoring point 16. A predetermined pressure is reached quickly. Further, the pressure drop at the pressure monitoring point 14 is smaller than that at the pressure monitoring point 16.

  From the above, the relief valve 30 starts opening earlier when the relief valve 30 is provided on the upstream side (upstream pressure reducing valve 22 side) in the gas supply passage 24, and the gas in the gas supply passage 24 is discharged. It can be discharged outside to reduce the pressure.

  The operation of the above configuration will be described. FIG. 3 is a graph showing the pressure characteristics of the gas supply flow path 24 when the relief valve 30 is operated with time on the horizontal axis and pressure on the vertical axis. The pressure characteristic curve 71 shows the pressure characteristic when the pressure of the gas supply flow path 24 increases and the relief valve 30 is activated. A boundary line 72 indicates a valve opening pressure (for example, 4 MPa) at which the relief valve 30 starts to open. The boundary line 73 indicates the pressure pressure and the lowest pressure pressure value (for example, 10 MPa) among the pressure pressures that damage the pipes and the downstream pressure reducing valves 28 that are the flow path elements of the gas supply flow path 24. Yes.

  For example, when the upstream pressure reducing valve 22 that depressurizes the high-pressure gas from the fuel gas tank 20 malfunctions, the pressure in the gas supply channel 24 increases toward the pressure value of the high-pressure gas. The relief valve 30 is arranged at a position downstream of the upstream pressure reducing valve 22 so that the pipe line resistance between the upstream pressure reducing valve 22 and the relief valve 30 is the smallest, and in the vicinity of the relief valve 30 When the pressure exceeds the pressure value indicated by the boundary line 72, the relief valve 30 opens. After the relief valve 30 is opened, the gas is discharged to the outside of the gas supply flow path 24, and the pressure is lowered so as not to exceed the pressure value indicated by the boundary line 73.

  As described above, in the gas supply flow path 24, the pressure in the vicinity of the relief valve 30 decreases without exceeding the pressure resistance. Further, the pressure on the downstream side of the relief valve 30 does not exceed the pressure resistance because the pressure increase rate is slower. Therefore, the pressure of the gas supply flow path 24 can be reduced without damaging the piping or the downstream pressure reducing valve 28 which are flow path elements of the gas supply flow path 24.

  A volume portion 26 is provided on the downstream side of the relief valve 30. The volume part 26 can suppress the pressure increase rate of the gas supply flow path 24 as described above. Therefore, the pressure increase rate when the upstream pressure reducing valve 22 is malfunctioning can be slower than the pressure decreasing rate caused by the gas discharge by the relief valve 30. Therefore, the piping of the gas supply flow path 24 and the downstream pressure reducing valve can be more appropriately performed. Damage to the valve 28 can be suppressed.

  Further, since the channel diameter of the gas supply channel 24 is equal to or larger than the valve diameter of the relief valve 30, the relief valve 30 is opened before reaching the pressure at which the gas supply channel 24 is damaged. This improves the reliability of the function.

  As described above, according to the present invention, the pressure of the gas supply passage 24 can be reduced without damaging the piping of the gas supply passage 24 or the downstream pressure reducing valve 28. In the above description, the relief valve 30 has been described as being disposed at a position where the pipe resistance between the upstream pressure reducing valve 22 and the relief valve 30 is minimized. The valve 30 has the same effect as an integrated structure. Further, the upstream pressure reducing valve 22, the relief valve 30 and the volume portion 26 are integrated, and the pressure of the gas supply flow path 24 is more appropriately damaged without damaging the piping of the gas supply flow path 24 and the downstream pressure reducing valve 28. Can be lowered.

It is a figure which shows the structure of the fuel cell system of embodiment of this invention. It is a figure which shows the pressure rise value of the gas supply flow path when time is taken on a horizontal axis and an upstream pressure-reduction valve malfunctions when pressure is taken on a vertical axis | shaft. It is a figure which shows the characteristic of the pressure of the arrangement position of a relief valve in a gas supply flow path when time is taken on a horizontal axis and pressure is taken on a vertical axis and a relief valve is operated.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Fuel cell system, 12 Fuel cell stack, 14, 16 Pressure monitoring point, 20 Fuel gas tank, 22 Upstream pressure reducing valve, 24 Gas supply flow path, 26 Volume part, 28 Downstream pressure reducing valve, 30 Relief valve, 32 Fuel gas Shut valve, 34 circulation booster, 36 shunt, 38 exhaust valve, 40 oxidizing gas source, 50 diluter, 61, 62, 71 pressure characteristic curve, 72, 73 boundary line.

Claims (4)

A high-pressure gas tank filled with high-pressure gas;
A gas supply channel for supplying gas from a high-pressure gas tank disposed on the upstream side to a fuel cell stack disposed on the downstream side;
An upstream pressure reducing valve provided on the upstream side of the gas supply flow path to depressurize the high pressure gas;
A downstream pressure reducing valve that is provided on the downstream side of the gas supply flow path and further depressurizes the gas after being decompressed by the upstream pressure reducing valve;
A relief valve that is disposed between the upstream side pressure reducing valve and the downstream side pressure reducing valve in the gas supply flow path and opens when the pressure of the gas supply flow path at the arrangement position exceeds a predetermined threshold value. When,
With
The relief valve
A fuel cell system, wherein the pressure of the gas supply flow path at the arrangement position is arranged at a position that does not exceed the pressure resistance value of the flow path element downstream from the arrangement position. The fuel cell system according to claim 1,
A volume supply section provided between the relief valve and the downstream pressure reducing valve in the gas supply flow path and having a flow path diameter larger than the flow path diameter of the gas supply flow path;
With
The relief valve
A fuel cell system that opens when a pressure between an upstream pressure reducing valve and a volume part exceeds a predetermined threshold in a gas supply flow path. The fuel cell system according to claim 1 or 2,
A fuel cell system, wherein an upstream pressure reducing valve and a relief valve are integrated. In the fuel cell system according to any one of claims 1 to 3,
A fuel cell system, wherein a gas supply channel has a larger diameter than a relief valve.

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