JP2006048987A - Fuel cell device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell device capable of collecting generated water in any optional timing without discharging unreacted fuel gas to the outside of a system even if the amount of generated water is not much when collecting water generated in a fuel cell. <P>SOLUTION: This fuel cell device is equipped with a water storage part 55 which is in communication with a fuel cell discharging passage 32 to pass the unreacted fuel gas discharged from the fuel cell 20 to store moisture contained in the unreacted fuel gas, an isolating means A3 to isolate the water storage part 55 from the fuel cell discharging passage 32 when draining water stored in the water storage part 55, and a discharge means 35 to discharge the unreacted fuel gas contained in the water storage part 55 isolated from the fuel gas discharging passage 32 to a fuel gas discharging passage 33. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fuel cell device, and more particularly to an improved technique for suppressing leakage of unreacted fuel gas during water recovery.

  FIG. 3 shows the main configuration of a conventional fuel cell evaluation apparatus 80. A fuel gas (hydrogen) is supplied to the anode electrode of the fuel cell 20 via the fuel gas channel 31, and an oxidizing gas (oxygen) is supplied to the cathode electrode via the oxidizing gas channel 41. The flow rates of the fuel gas and the oxidant gas are controlled by the mass flow controllers 51 and 61, are appropriately humidified by the humidifiers 52 and 62, and then heated by the heaters 53 and 63. The hydrogen off-gas (anode off-gas) and oxygen off-gas (cathode off-gas) after being subjected to the cell reaction are discharged from the fuel cell 20 through the fuel gas discharge channel 32 and the oxidizing gas discharge channel 42, respectively. Liquid separation. The hydrogen off-gas and oxygen off-gas that have passed through the gas-liquid separator 70 further flow into drain pods (reservoir units) 54 and 64, and after residual moisture is extracted, the fuel off-gas passage 34 and the oxidizing gas discharge passage 43 are passed through. Exhausted. The back pressures of the hydrogen off gas and the oxygen off gas are regulated by back pressure valves A1 and A2. By the way, since the hydrogen off-gas and oxygen off-gas contain moisture generated by the cell reaction, the back-pressure valve A1 directly sends off-gas from the fuel cell 20 without going through the gas-liquid separator 70 and the drain pods 54 and 64. , A 2, moisture gradually begins to accumulate in the orifices of the back pressure valves A 1, A 2 to form a liquid film. If the liquid film grows to some extent, it may be blown away due to the influence of back pressure, causing unexpected back pressure fluctuations. For this reason, a gas-liquid separator 70 and drain pods 54 and 64 for removing moisture from off-gas are installed between the fuel cell 20 and the back pressure valves A1 and A2. The sample water stored in the drain pods 54 and 64 is collected by opening the drain valves A5 and A6 and used for component analysis.

For example, Japanese Patent Application Laid-Open No. 8-195209 and Japanese Patent Application Laid-Open No. 8-195215 are known as other conventional techniques related to a water recovery device for a fuel cell. In JP-A-8-195215, a first tank that branches downward from a reaction gas flow path connected to a fuel cell and communicates therewith, and a second tank that communicates with the lower part of the first tank, and further, A first valve is installed in the flow path connecting these tanks, a second valve is installed on the outlet side of the second tank, and the first valve and the second valve are alternately opened and closed. Thus, a configuration for draining water contained in the reaction gas is disclosed. A water-permeable shielding plate (hydrophilic porous plate) that prevents gas permeation and allows moisture permeation is installed at the inflow port of the first tank. When draining from the second tank, Hydrogen gas is configured not to be exhausted outside the system.
JP-A-8-195209 JP-A-8-195215

  However, in the configuration shown in FIG. 3, since the drain pods 54 and 64 are installed upstream of the back pressure valves A1 and A2, the sample water stored in the drain pods 54 and 64 is being tested (during battery operation). If it is collected, the pressure in the drain pods 54 and 64 changes, causing a pressure fluctuation, which affects the back pressure control. Furthermore, since the drain pod 54 is filled with hydrogen gas, if the sample water stored in the drain pod 54 is completely removed during the test, the hydrogen gas leaks out of the system through the drain valve A5. There is a fear. In order to avoid such inconvenience, it is necessary to stop the test and replace the hydrogen filled in the drain pod 54 with nitrogen, and then open the drain valve A5 to collect the sample water. Test efficiency is reduced.

  Further, in the configuration disclosed in Japanese Patent Application Laid-Open No. 8-195215, if the second tank is drained before it is full, hydrogen gas may be discharged out of the system together with water. Further, since the second tank is configured not to drain unless it is full, it cannot be drained at an arbitrary timing. Moreover, in order to prevent gas permeation by the water-permeable shielding plate, it is necessary that all the through holes of the water-permeable shielding plate are closed with moisture, but when the amount of water supplied to each tank is small, There is a possibility that the hydrogen gas is filled in each tank without blocking the through hole of the conductive shielding plate.

  Therefore, the present invention recovers the generated water at an arbitrary timing without discharging unreacted fuel gas outside the system even when the amount of generated water is small in recovering the water generated in the fuel cell. It is an object of the present invention to propose a fuel cell device and a fuel cell evaluation device that can be used.

  In order to solve the above-described problem, the fuel cell device of the present invention stores water contained in unreacted fuel gas in communication with a fuel gas discharge channel for flowing unreacted fuel gas discharged from the fuel cell. A water storage section, a blocking means for blocking the water storage section from the fuel gas discharge flow path when draining water stored in the water storage section, and an unreacted fuel gas contained in the water storage section blocked from the fuel gas discharge flow path. A discharge means for discharging to the fuel gas discharge flow path. When collecting water from the water storage unit, the water storage unit and the fuel gas discharge channel are shut off, and the unreacted fuel gas that fills the water storage unit is discharged to the fuel gas discharge channel. The generated water can be drained at an arbitrary timing without leaking. Further, when the fuel cell device of the present invention is mounted on a vehicle, the amount of water retained in the fuel cell device can be reduced, so that fuel efficiency can be improved.

  Here, as the discharging means, a means for replacing the unreacted fuel gas present in the water reservoir with an inert gas is desirable. Unreacted fuel gas can be easily discharged by purging the inert gas into the water reservoir that is disconnected from the fuel gas discharge channel.

  In the fuel cell device of the present invention, a back pressure valve for regulating the back pressure of the fuel gas is disposed in the fuel gas discharge passage between the fuel cell and the water storage section. By installing the back pressure valve on the upstream side of the water storage section, there is no possibility that the pressure fluctuation in the water storage section accompanying the water recovery from the water storage section will affect the back pressure control of the back pressure valve.

  The fuel cell evaluation apparatus of the present invention includes the fuel cell apparatus of the present invention and analysis means for analyzing a component of water recovered from the water storage unit. By analyzing the components of the water produced in the fuel cell, the characteristics of the fuel cell can be evaluated. In addition, since the generated water can be drained at an arbitrary timing, detailed analysis and evaluation in time series is possible.

  According to the present invention, when collecting water from the water storage unit, the water storage unit and the fuel gas discharge channel are shut off, and the unreacted fuel gas existing in the water storage unit is discharged to the fuel gas discharge channel, thereby allowing unreacted The generated water can be drained at an arbitrary timing without leaking the fuel gas outside the system.

  1 and 2 are configuration diagrams of a fuel cell evaluation apparatus 10 according to the present embodiment. The devices having the same reference numerals as those in FIG. 3 indicate the same devices, and detailed description thereof is omitted. In the drawings, in various piping systems, a solid line indicates a portion where gas (hydrogen gas, oxygen gas, inert gas, etc.) or liquid (sample water, etc.) flows, and a dotted line indicates a portion where gas or liquid does not flow. Show.

  The water recovery system on the anode side of the fuel cell evaluation apparatus 10 has a two-stage configuration in which a sample pod (water storage unit) 55 and a drain pod 54 are connected in multiple stages (cascade connection). A three-way valve A3 is installed in the discharge path of hydrogen off gas (unreacted fuel gas), and the discharge path of hydrogen off gas can be switched. The port P1 of the three-way valve A3 communicates with the fuel gas discharge passage 32, the port P2 communicates with the sample pod 55, and the port P3 communicates with the fuel gas discharge passage 34. The fuel gas discharge flow path 34 connects the port P3 and the drain pod 54, and is configured to exhaust the hydrogen off gas existing in the drain pod 54 to the outside of the system. The fuel gas discharge channel 33 is a gas channel for exhausting the hydrogen off-gas introduced into the sample pod 55 to the outside of the system, and merges with the fuel gas discharge channel 34 downstream thereof. Downstream of the fuel gas discharge passages 33 and 34 are check valves A7 and A8 for suppressing the backflow of hydrogen offgas, and further on the downstream side for dilution to dilute the hydrogen offgas to a sufficiently low concentration. A vessel (not shown) is installed. Further, the sample pod 55 communicates with an inert gas flow path 35 for replacing the hydrogen off gas in the pod with an inert gas (nitrogen gas, argon gas, etc.) and discharging the hydrogen off gas to the fuel gas discharge flow path 33. is doing.

  Next, a sample water recovery operation will be described. During normal operation, as shown in FIG. 1, by connecting ports P1 and P2 and closing port P3, hydrogen offgas is introduced into the sample pod 55, and moisture contained in the hydrogen offgas is removed from the sample pod. Store in 55. The hydrogen off-gas introduced into the sample pod 55 through the fuel gas discharge channel 32 is discharged out of the system through the fuel gas discharge channel 33. In order to recover the sample water stored in the sample pod 55 in this way, as shown in FIG. 2, the port P1 and the port P3 are communicated and the port P2 is closed, so that the hydrogen off-gas is drained from the drain pod. Then, the hydrogen off-gas is stored in the drain pod 55. The hydrogen off-gas introduced into the drain pod 54 through the fuel gas discharge passage 32 is discharged out of the system through the fuel gas discharge passage 34. In this way, when the hydrogen off-gas discharge path is switched, the shutoff valve A4 is opened to introduce the inert gas into the sample pod 55, and the hydrogen off-gas present in the sample pod 55 is converted into the inert gas. Replace with. As a result, the hydrogen off-gas existing in the sample pod 55 is pushed away to the fuel gas discharge passage 33 and exhausted outside the system. When the hydrogen off-gas in the sample pod 55 is replaced with an inert gas, the drain valve A5 is opened to collect the sample water. The collected sample water is subjected to component analysis by the analyzing means 71 and used for characteristic evaluation of the fuel cell 20. As described above, the three-way valve A3 functions as a blocking unit that blocks communication between the sample pod 55 and the fuel gas discharge channel 32, and the inert gas channel 35 and the cutoff valve A4 discharge hydrogen off-gas from the sample pod 55. Functions as a discharging means.

  In addition to the above-described configuration, the fuel cell evaluation apparatus 10 includes a back pressure valve A1 that adjusts the back pressure of the fuel gas between the anode outlet of the fuel cell 20 and the sample pod 55 (before or upstream of the sample pod 55). A back pressure valve A2 for adjusting and adjusting the back pressure of the oxidizing gas is disposed between the cathode side outlet of the fuel cell 20 and the drain pod 64 (before or upstream of the drain pod 64). With this configuration, when sample water is collected from each of the sample pod 55 and the drain pod 64, a pressure change caused by a decrease in the water level of the sample pod 55 and the drain pod 64 does not affect the back pressure valves A1 and A2.

  Further, heaters 53 and 63 are installed between the anode-side outlet or cathode-side outlet of the fuel cell 20 and the back pressure valves A1 and A2, and the hydrogen off-gas or oxygen off-gas is kept at an appropriate temperature so that the back-pressure valves A1 and A2 are transferred. The water supply can be suppressed. When moisture is supplied to the back pressure valves A1 and A2, moisture begins to accumulate in the orifices of the back pressure valves A1 and A2, and a liquid film is formed. When the liquid film grows to a certain extent, it is blown away due to the back pressure, Since unexpected back pressure fluctuations may occur, it is preferable to suppress water supply to the back pressure valves A1 and A2 as much as possible. The heating capacity of the heaters 53 and 63 is preferably one that can keep offgas moderately and raise the temperature to a temperature at which offgas-containing water does not condense. As the off-gas temperature, for example, around 90 ° C. is suitable. The heaters 53 and 63 are installed as evenly as possible between the fuel cell 20 and the back pressure valves A1 and A2 (and between the humidifiers 52 and 62 and the fuel cell 20). It is desirable that the temperature distribution is not generated. As the heaters 53 and 63, for example, by using a ribbon heater, the heaters 53 and 63 can be easily attached by being wound around the fuel gas discharge passage 32 and the oxidizing gas discharge passage 42, for example. As the fuel gas discharge channel 32 and the oxidant gas discharge channel 42, those excellent in thermal conductivity suitable for heater heating are suitable.

  According to the present embodiment, the configuration is such that the sample water is recovered after replacing the hydrogen offgas present in the sample pod 55 with an inert gas, and therefore there is no possibility that the hydrogen offgas leaks out of the system when the sample water is recovered. . Further, when the fuel cell device of the present invention is mounted on a vehicle, the amount of water retained in the fuel cell device can be reduced, so that fuel efficiency can be improved. Furthermore, as a condition for collecting the sample water, the sample pod 55 does not need to be full, so the sample water can be collected at an arbitrary timing. Further, when the sample water is subjected to component analysis by the analyzing means 71, detailed evaluation in time series becomes possible. Further, by arranging the back pressure valves A1 and A2 on the upstream side of the sample pod 55 or the drain pod 64, the back pressure control of the back pressure valves A1 and A2 is not affected during sample water recovery.

It is a block diagram of the fuel cell evaluation apparatus of this embodiment. It is a block diagram of the fuel cell evaluation apparatus of this embodiment. It is a block diagram of the conventional fuel cell evaluation apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Fuel cell evaluation apparatus 20 ... Fuel cell 32, 33, 34 ... Fuel gas discharge flow path 42 ... Oxidation gas discharge flow path 54 ... Drain pod 55 ... Sample pod 64 ... Drain pod 71 ... Analytical means A1, A2 ... Back pressure valve A3 ... Three-way valve A4 ... Shut-off valve A5, A6 ... Drain valve

Claims (4)

  A water storage part that stores water contained in the unreacted fuel gas in communication with a fuel gas discharge passage for flowing unreacted fuel gas discharged from the fuel cell, and drains water stored in the water storage part A shutoff means for shutting off the water storage section from the fuel gas discharge flow path, and a discharge for discharging unreacted fuel gas contained in the water storage section cut off from the fuel gas discharge flow path to the fuel gas discharge flow path. And a fuel cell device.   2. The fuel cell device according to claim 1, wherein the discharge unit is a unit that replaces an unreacted fuel gas existing in the water storage unit with an inert gas. 3.   3. The fuel cell device according to claim 1, wherein a back pressure valve for adjusting a back pressure of the fuel gas is disposed in a fuel gas discharge passage between the fuel cell and the water storage unit. The fuel cell device. A fuel cell evaluation device comprising: the fuel cell device according to any one of claims 1 to 3; and an analysis unit that analyzes a component of moisture recovered from the water storage unit.

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