JP2006066106A - Fuel cell system and starting method of the fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell system capable of appropriately coping with the problem of acceleration in drying for an electrolyte film, local reaction or the like, and to stabilize the performance of a fuel cell. <P>SOLUTION: The fuel cell system is provided with a fuel cell 121 for generating power from fuel gas and an oxidant; a fuel gas supplying piping 161 as a fuel gas supplying means supplying the fuel gas to the anode side of the fuel cell, as well as a first switching valve 129; an oxidizing gas supply piping 162 as an oxidant gas supplying means for supplying an oxidant to a cathode side of the fuel cell, as well as a second shut-off valve 131; a raw gas supplying piping 151 as a raw gas supplying means for supplying a raw material of the fuel gas to the fuel cell, as well as a third switching valve 143; and a control part 127 for controlling the supply of the fuel gas, supply of the oxidant and supply of the raw material. By the control of the control part 127, the cathode side of the fuel cell is purged, at the start of power generation of the fuel cell. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fuel cell system and a startup method thereof.

  The configuration and operation of a conventional general solid polymer electrolyte fuel cell will be described with reference to FIGS. FIG. 1 shows a basic structure of a polymer electrolyte fuel cell (hereinafter referred to as PEFC) among conventional fuel cells. A fuel cell is one that causes a fuel gas such as hydrogen and an oxygen-containing gas such as air to react electrochemically with a gas diffusion electrode, and generates electricity and heat simultaneously. As the electrolyte 1, a polymer electrolyte membrane that selectively transports hydrogen ions is used. A catalyst reaction layer 2 mainly composed of carbon powder carrying a platinum-based metal catalyst is disposed on both surfaces of the electrolyte 1 in close contact with each other. Reactions represented by (Chemical Formula 1) and (Chemical Formula 2) occur in this catalytic reaction layer, and a reaction represented by (Chemical Formula 3) occurs in the fuel cell as a whole.

(Chemical formula 1)
H ₂ → 2H ⁺ + 2e ⁻
(Chemical formula 2)
1 / 2O ₂ + 2H ⁺ + 2e ⁻ → H ₂ O
(Chemical formula 3)
H ₂ + 1 / 2O ₂ → H ₂ O
The fuel gas containing at least hydrogen (hereinafter referred to as anode gas) undergoes the reaction shown in (Chemical Formula 1) (hereinafter referred to as anode reaction), and the hydrogen ions moved through the electrolyte 1 are converted into oxygen-containing gas (hereinafter referred to as cathode). Water is generated by the reaction shown in (Chemical Formula 2) in the catalytic reaction layer 2 (hereinafter referred to as the cathode reaction) and electricity and heat are generated at this time. As shown in (Equation 3), the fuel cell as a whole can use electricity and heat when hydrogen and oxygen react to generate water. The side in which a fuel gas such as hydrogen is involved is called an anode, and a is added in the figure, the side in which an oxygen-containing gas such as air is involved is called a cathode, and c is shown in the figure. Furthermore, diffusion layers 3a and 3c having both gas permeability and conductivity are disposed in close contact with the outer surfaces of the catalyst reaction layers 2a and 2c. The diffusion layers 3a and 3c and the catalyst reaction layers 2a and 2c constitute electrodes 4a and 4c. Reference numeral 5 denotes an electrode electrolyte assembly (hereinafter referred to as MEA), which is formed by the electrode 4 and the electrolyte 1. The MEA 5 is used for mechanically fixing the MEA 5 and electrically connecting adjacent MEAs 5 to each other, supplying a reaction gas to the electrodes, and carrying away a gas generated by the reaction and excess gas. A pair of conductive separators 7a and 7c, in which the gas flow paths 6a and 6c are formed on the surface in contact with the MEA 5, are disposed. A basic fuel cell unit (hereinafter referred to as a cell) includes an electrolyte 1, a pair of catalytic reaction layers 2a and 2c, a pair of diffusion layers 3a and 3c, a pair of electrodes 4a and 4c, and a pair of separators 7a and 7c. Form. The separators 7a and 7c are in contact with the separators 7c and 7a of the adjacent cells on the surface opposite to the MEA 5. The cooling water passage 8 is provided on the side where the separators 7a and 7c are in contact, and the cooling water 9 flows there. The cooling water 9 moves heat so as to adjust the temperature of the MEA 5 through the separators 7a and 7c. The MEA gasket 10 seals the MEA 5 and the separator 7a or 7c, and the separator gasket 11 seals the separators 7a and 7c.

  The electrolyte 1 has a fixed charge, and hydrogen ions exist as counter ions of the fixed charge. The electrolyte 1 is required to have a function of selectively allowing hydrogen ions to permeate. For this purpose, the electrolyte 1 needs to retain moisture. This is because when the electrolyte 1 contains moisture, the fixed charge fixed in the electrolyte 1 is ionized, and hydrogen, which is a counter ion of the fixed charge, is ionized and can move.

  The stack will be described with reference to FIG. Since the voltage of the fuel cell is usually as low as about 0.75 V, a plurality of cells are stacked in series so that the voltage becomes high. The current collecting plate 21 is for taking out current from the stack to the outside, and the insulating plate 22 electrically insulates the cell from the outside. The end plate 23 fastens and stacks a stack of cells.

  A conventional fuel cell system will be described with reference to FIG. A fuel cell system is housed in the outer casing 31. The gas cleaning unit 32 removes a substance that adversely affects the fuel cell from the fuel gas, and guides the fuel gas from the outside through the raw material gas pipe 33. The valve 34 controls the flow of the raw material gas. The fuel generator 35 generates a fuel gas containing at least hydrogen from the raw material gas. The fuel gas is led from the fuel generator 35 to the stack 38 via the fuel gas pipe 37. The blower 39 guides the oxidant gas to the stack 38 through the intake pipe 40. The exhaust pipe 42 discharges the oxidant gas discharged from the stack 38 to the outside of the fuel cell system. The fuel gas that has not been used in the stack 38 flows again into the fuel generator 35 through the off-gas pipe 48. The gas from the off-gas pipe 48 is used for combustion or the like, and is used for an endothermic reaction or the like for generating a fuel gas from the raw material gas. The power circuit unit 43 extracts power from the fuel cell stack 38, and the control unit 44 controls the gas, the power circuit unit, and the like. The pump 45 causes water to flow from the cooling water inlet pipe 46 to the water path of the fuel cell stack 38. The water that has flowed through the fuel cell stack 38 is carried to the outside from the cooling water outlet pipe 47. By flowing water through the stack 38 of the fuel cell, the generated heat can be used outside the fuel cell system while maintaining the heated stack 38 at a constant temperature. The fuel cell system includes a stack 38 composed of fuel cells, a gas cleaning unit 32, a fuel generator 35, a power circuit unit 43, and a control unit 44.

The home fuel cell system includes a fuel cell stack 38 and a fuel generator 35. It is necessary to reduce the performance degradation of the fuel cell system so that the performance can be maintained for a long time. In addition, when source gas such as city gas mainly composed of methane is used for household use, it stops during periods of low electricity and heat consumption in order to increase the utility cost and CO ₂ reduction effect. An operation method that operates in a time zone where consumption of electricity and heat is large is effective.

In general, DSS (Daily Start & Stop or Daily Start-up & Shut-down) operation, which operates in the daytime and stops at midnight, can increase the utility cost and CO ₂ reduction effect. It is desirable to be able to respond flexibly to operation patterns including start and stop. Several reports have been made so far.

For example, as a solution to these problems, a means for consuming electric power is separately connected in the system until starting the external load connection of the system at the start-up, thereby preventing an open circuit potential (see Patent Document 1). Moreover, the discharge means for suppression of an open circuit voltage was installed in the system (refer patent document 2). Further, in order to keep the ion exchange membrane, which is an electrolyte, in a water retaining state during storage, the humidified inert gas is sealed and stored (see Patent Document 3). In order to prevent oxidation of the oxygen electrode or adhesion of impurities, power generation was performed with the supply of the oxygen-containing gas stopped, and oxygen consumption operation was performed to improve durability (see Patent Document 4). Further, hydrogen leaking from the anode to the cathode is used to improve the performance of the cathode electrode (see Patent Document 5).
Japanese Patent Laid-Open No. 5-251101 JP-A-8-222258 JP-A-6-251788 JP 2002-93448 A JP 2000-260454 A

  However, according to the above-described conventional method for stopping and storing the fuel cell, although it is disclosed that the inside of the fuel cell is replaced with a humidified inert gas for the purpose of preventing the drying of the electrolyte membrane from being accelerated, The method has the following items to be improved.

  First, even if the fuel cell is sealed off from the external atmosphere, when the fuel cell is stored for a certain period (for example, about 15 hours to 3 days), air (oxygen gas) is fueled from the sealed portion. There is a possibility of leaking inside the battery and mixing. In particular, in the humidified inert gas introduction method described in Patent Document 3 (introduction immediately after stopping), the water vapor contained in the humidified inert gas is condensed due to the temperature drop inside the fuel cell, and negative pressure is promoted. Concerns about oxygen gas contamination are further increased. Under such circumstances, if hydrogen-rich fuel gas is supplied when the fuel cell is restarted, the local reaction of oxygen gas and fuel gas at the anode of the fuel cell leads to damage of the fuel cell or deterioration of the performance of the fuel cell. It might be.

  The present invention has been made in view of the above circumstances, and its object is to appropriately cope with problems such as acceleration of drying of the electrolyte membrane and local reaction, and a fuel cell system capable of stabilizing the performance of the fuel cell. It is to provide a starting method.

In order to achieve the above object, a first aspect of the present invention provides a fuel cell that generates electric power from a fuel gas and an oxidant gas;
Fuel gas supply means for supplying the fuel gas to the anode side of the fuel cell;
Oxidant gas supply means for supplying the oxidant gas to the cathode side of the fuel cell;
A raw material gas supply means for supplying the raw material gas of the fuel gas to the fuel cell;
Control means for controlling the fuel gas supply means, the oxidant gas supply means and the source gas supply means,
By the control of the control means,
When starting power generation of the fuel cell,
Before the oxidant gas supply means and the fuel gas supply means supply the fuel gas and the oxidant gas to the fuel cell, the source gas supply means uses the source gas at least on the cathode side of the fuel cell. A fuel cell system for purging.

  The second aspect of the present invention is the fuel cell system according to the first aspect of the present invention, wherein the source gas supply means purges the anode side after purging the cathode side in the fuel cell.

The third aspect of the present invention includes a fuel gas pipe provided between the fuel gas supply means and the cathode side of the fuel cell;
A fuel gas on-off valve provided in the middle of the fuel gas pipe;
An oxidant gas pipe provided between the oxidant gas supply means and the anode side of the fuel cell;
An oxidant gas on-off valve provided in the middle of the oxidant gas pipe;
A source gas pipe connected to a part of the oxidant gas pipe between the source gas supply means, the oxidant gas on-off valve and the cathode side of the fuel cell;
A source gas on-off valve provided in the middle of the source gas pipe,
It is a fuel cell system according to the first or second aspect of the present invention.

The fourth aspect of the present invention is a cathode side discharge pipe for discharging off gas discharged from the cathode side of the fuel cell;
A cathode-side off-gas on-off valve provided in the middle of the cathode-side exhaust pipe;
The purge,
Open the cathode side off-gas on-off valve,
The fuel cell system according to a third aspect of the present invention is performed by opening and closing the source gas on-off valve after a predetermined period.

The fifth aspect of the present invention includes the source gas supply means and an additional source gas pipe connected to a portion of the source gas pipe between the fuel gas on-off valve and the anode side of the fuel cell. ,
An additional raw material gas on-off valve provided in the middle of the additional raw material gas pipe;
An anode side discharge pipe for discharging off-gas discharged from the anode side of the fuel cell;
An anode-side off-gas on-off valve provided in the middle of the anode-side exhaust pipe,
The purge,
After opening the source gas on-off valve,
Furthermore, open the anode side off-gas on-off valve,
The fuel cell system according to a fourth aspect of the present invention is performed by opening the additional source gas on-off valve for a predetermined period.

According to a sixth aspect of the present invention, the oxidant gas supply means and the fuel gas supply means supply the fuel gas and the oxidant gas to the fuel cell.
After opening the anode-side off-gas on-off valve, open the fuel gas on-off valve,
Next, the fuel cell system according to the fifth aspect of the present invention is performed by opening the cathode-side off-gas on-off valve and then opening the oxidant gas on-off valve.

A seventh aspect of the present invention is a fuel cell for generating electric power from a fuel gas and an oxidant gas, an oxidant gas supply means for supplying an oxidant gas to the fuel cell, and the fuel gas to the fuel cell. A fuel cell system start-up method comprising fuel supply means for supplying,
When starting power generation of the fuel cell,
Prior to supplying the fuel gas and the oxidant gas to the fuel cell, at least a cathode side of the fuel cell is purged with a raw material gas used to generate the fuel gas, and a method for starting a fuel cell power generation system .

  The eighth aspect of the present invention is the fuel cell system start-up method according to the seventh aspect of the present invention, wherein the anode side is purged after purging the cathode side in the fuel cell.

  According to a ninth aspect of the present invention, there is provided a fuel cell system start-up method according to the seventh aspect of the present invention, prior to supplying the fuel gas and the oxidant gas to the fuel cell when starting the power generation of the fuel cell. And a program for controlling, by a computer, a step of purging at least the cathode side of the fuel cell with the raw material gas used to generate the fuel gas.

  The tenth aspect of the present invention is a recording medium carrying the program of the ninth aspect of the present invention, which can be processed by a computer.

  According to the present invention, by exposing the inside of the fuel cell to the humidified raw material gas atmosphere at an appropriate timing, it is possible to appropriately cope with problems such as accelerated drying of the electrolyte membrane and local reactions, and to stabilize the performance of the fuel cell. You can plan.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(Embodiment 1)
FIG. 1 shows a basic configuration of a polymer electrolyte fuel cell as an example of the fuel cell according to Embodiment 1 of the present invention. In a fuel cell, a fuel gas containing at least hydrogen and an oxidant gas containing oxygen such as air are electrochemically reacted by a gas diffusion electrode, and electricity and heat are generated simultaneously. The electrolyte 1 is used by a polymer electrolyte membrane that selectively transports hydrogen ions. A catalyst reaction layer 2 mainly composed of carbon powder carrying a platinum-based metal catalyst is disposed on both surfaces of the electrolyte 1 in close contact with each other. Reactions represented by (Chemical Formula 1) and (Chemical Formula 2) occur in the catalytic reaction layers 2a and 2c. The fuel gas containing at least hydrogen undergoes the reaction shown in (Equation 1) (hereinafter referred to as an anode reaction), and the hydrogen ions moved through the electrolyte 1 are shown in (Equation 2) in the oxidant gas and the catalytic reaction layer 2. The reaction (hereinafter referred to as the cathodic reaction) produces water, which generates electricity and heat. The side in which fuel gas such as hydrogen is involved is called an anode, and a is added in the figure, the side in which oxidant gas such as air is involved is called a cathode, and C is shown in the figure. Furthermore, diffusion layers 3a and 3c having both gas permeability and conductivity are arranged in close contact with the outer surfaces of the catalyst reaction layers 2a and 2c, respectively. The diffusion layer 3a and the catalyst reaction layer 2a constitute an electrode 4a, and the diffusion layer 3c and the catalyst reaction layer 2c constitute an electrode 4c. A membrane electrode assembly (hereinafter referred to as MEA) 5 is formed of electrodes 4 a and 4 c and an electrolyte 1. The MEA 5 is used for mechanically fixing the MEA 5 and electrically connecting adjacent MEAs 5 to each other, supplying a reaction gas to the electrodes, and carrying away a gas generated by the reaction and excess gas. A pair of conductive separators 7a and 7c, in which the gas flow paths 6a and 6c are formed on the surface in contact with the MEA 5, are disposed. A basic fuel cell (hereinafter referred to as a cell) comprising an electrolyte 1, a pair of catalytic reaction layers 2a and 2c, a pair of diffusion layers 3a and 3c, a pair of electrodes 4a and 4c, and a pair of separators 7a and 7c. Form. The separators 7a and 7c are in contact with the separators 7c and 7a of the adjacent cells on the surface opposite to the MEA 5. A cooling water passage 8 is provided on the side where the separators 7a and 7c are in contact, and the cooling water 9 flows there. The cooling water 9 moves heat so as to adjust the temperature of the MEA 5 through the separators 7a and 7c. The MEA 5 and the separator 7 a or 7 c are sealed with the MEA gasket 10, and the separators 7 a and 7 c are sealed with the separator gasket 11.

  The electrolyte 1 has a fixed charge, and hydrogen ions exist as a counter ion of the fixed charge. The electrolyte 1 is required to have a function of selectively allowing hydrogen ions to permeate. For this purpose, the electrolyte 1 needs to retain moisture. This is because when the electrolyte 1 contains moisture, the fixed charge fixed in the electrolyte 1 is ionized, and hydrogen, which is a counter ion of the fixed charge, is ionized and can move.

  FIG. 2 is a stack of cells and is called a stack. Since the voltage of the fuel cell is usually as low as about 0.75 v, a plurality of cells are stacked in series so as to obtain a high voltage. A current is taken out from the pair of current collecting plates 21 to the outside from the stack, the cell and the outside are electrically insulated by the pair of insulating plates 22, and the stack of the cells stacked is fastened by the pair of end plates 23. Retained.

  FIG. 3 is a configuration diagram of the fuel cell system according to the embodiment of the present invention. The fuel cell system is housed in the outer casing 31. The raw material gas taken in from the raw material gas pipe 33 from the outside is purified by the gas cleaning unit 32 that removes substances that adversely affect the fuel cell, and then guided to the fuel generator 35 through the clean gas pipe 36. An open / close valve 34 is provided in the path of the source gas pipe 33 to control the flow of the source gas. The fuel generator 35 generates a fuel gas containing at least hydrogen from the raw material gas. Reference numeral 38 denotes a stack, which is a fuel cell and a stack whose details are shown in FIGS. Fuel gas is led from the fuel generator 35 to the anode side of the stack 38 through the fuel gas pipe 37.

  The air as the oxidant gas is led from the outside through the intake pipe 40 by the blower 39 to the cathode side of the stack 38 via the distribution valve 56 and the oxidant gas pipe 40 a connected to the intake pipe 40. The oxidant gas that has not been used in the stack 38 is discharged out of the fuel cell system through the exhaust pipe 42. Since the fuel cell needs moisture, the oxidant gas flowing into the stack 38 is humidified by the humidifier 41. The fuel gas that has not been used in the stack 38 flows again into the fuel generator 35 through the off-gas pipe 48. The gas from the off-gas pipe 48 is used for combustion or the like, and is used for an endothermic reaction or the like for generating a fuel gas from the raw material gas. A distribution valve 60 is provided in the clean gas pipe 36, and a distribution valve 56 is also provided in the intake pipe 40. The distribution valve 60 and the distribution valve 56 are connected to the bypass pipe 55. Further, a bypass pipe 61 is provided between the bypass pipe 55 and the fuel gas pipe stack 38 and the distribution valve 60, and the bypass pipe 61 is provided with an on-off valve 62. The distribution valve 60 adjusts the amount of gas that flows to the fuel generator 35 side after the gas purified by the gas cleaning unit 32 and the amount of gas that flows to the side of the bypass pipe 55, and the distribution valve 56 is fed from the blower 39. The purified oxidant gas and the purified raw material gas sent from the bypass pipe 55 can be mixed at an arbitrary ratio and sent to the stack 38. The fuel gas pipe 37 is provided with an on-off valve 49, which shuts off the flow of gas in the fuel gas supply path of the stack 38 or controls the flow rate. The off gas pipe 48 is provided with an open / close valve 54 to block the gas flow in the fuel gas discharge path of the stack 38. The on-off valve 57 is provided in the oxidant gas supply path from the humidifier 41 to the stack 38, and shuts off or controls the flow of gas in the oxidant gas supply path of the stack 38. The on-off valve 58 is provided in the oxidant gas discharge path from the stack 38, and shuts off or controls the flow rate of the gas in the oxidant gas discharge path of the stack 38. A pressure gauge 59 a is provided in the fuel gas supply path of the on-off valve 49 and the stack 38, and the pressures of the fuel gas supply path and the fuel gas path in the stack 38 are measured. A pressure gauge 59 b is provided in the oxidant gas supply path of the on-off valve 57 and the stack 38, and the pressures in the oxidant gas supply path and the oxidant gas path in the stack 38 are measured. The voltage of the fuel cell stack 38 is measured by the voltage measuring unit 52, the electric power is taken out by the power circuit unit 43, and the valves provided in the pipes of the raw material gas, fuel gas, oxidant gas, off gas, and cooling water, and the open / close states Valves, power circuit units, and the like are controlled by the control unit 44. The pump 45 causes water to flow from the cooling water inlet pipe 46 to the water path of the fuel cell stack 38, and the water that has flowed through the fuel cell 38 is carried from the cooling water outlet pipe 47 to the outside. By flowing water through the stack 38 of the fuel cell, the generated heat can be used outside the fuel cell system while maintaining the heated stack 38 at a constant temperature.

  The fuel cell system includes a stack 38 composed of fuel cells, a gas cleaning unit 32, a fuel generator 35, a power circuit unit 43, and a control unit 44.

  The basic operation of the fuel cell system having the above configuration will be described. In FIG. 3, the valve 34 is opened, and the source gas flows from the source gas pipe 33 into the gas cleaning unit 32. Although hydrocarbon gas such as natural gas or propane gas can be used as the source gas, 13A of city gas which is a mixed gas of methane, ethane, propane and butane gas is used in this embodiment. As the gas cleaning part 32, a member for removing gas odorant such as TBM (tertiary butyl mercaptan), DMS (dimethyl sulfide), THT (tetrahydrothiofin) is used. This is because sulfur compounds such as odorants are adsorbed on the catalyst of the fuel cell to become a catalyst poison and inhibit the reaction. In the fuel generator 35, hydrogen is generated by the reaction shown in (Chemical Formula 9) or the like. The simultaneously generated carbon monoxide is removed so as to be 10 ppm or less by a shift or reaction as shown in (Chemical Formula 10) and a carbon monoxide selective oxidation reaction as shown in (Chemical Formula 11).

(Chemical 9)
CH ₃ + H ₂ O → 3H ₂ + CO (−203.0 KJ / mol)
(Chemical formula 10)
CO + nH ₂ O → kCO ₂ + (n−k) CO
(Chemical Formula 11)
CO + O ₂ → CO ₂
Here, when water is added in a minimum amount necessary for the reaction, a fuel gas containing hydrogen and moisture is created and flows into the fuel cell stack 38 via the fuel gas pipe 37. The oxidant gas passes through the humidifier 41 by the blower 39 and then flows into the stack 38. The exhaust gas of the oxidant gas is discharged to the outside through the exhaust pipe 42. As the humidifier 41, one that flows an oxidant gas into warm water, one that blows water into the oxidant gas, or the like can be used. In this embodiment, a total heat exchange type is used. In this case, when water and heat in the exhaust gas pass through the humidifier 41, they are carried from the intake pipe 40 and moved into the oxidant gas as the raw material. The cooling water flows from the cooling water inlet pipe 46 to the water path of the fuel cell stack 38 from the pump 45, and then the water is carried to the outside from the cooling water outlet pipe 47.

  Although not shown in the figure, the cooling water inlet pipe 45 and the cooling water outlet pipe 47 are connected to a device for accumulating or using heat such as a normal water heater. The heat generated in the fuel cell stack 38 is taken out and can be used for hot water supply or the like. In the power generation in the stack 38, the voltage is measured by the voltage measurement unit 52, and when the control unit 44 determines that the power generation is sufficiently performed, the power circuit unit 43 extracts the power. In the power circuit unit 43, the DC power taken out from the stack 38 is converted into AC and connected to a power line used at home or the like by so-called system linkage.

  The operation of the fuel cell in the stack 38 will be described with reference to FIG. An oxygen-containing gas such as air flows through the gas flow path 6C, and a fuel gas containing hydrogen flows through the gas flow path 6a. Hydrogen in the fuel gas diffuses through the diffusion layer 3a and reaches the catalytic reaction layer 2a. In the catalytic reaction layer 2a, hydrogen is divided into hydrogen ions and electrons. The electrons are moved to the cathode side through an external circuit. The hydrogen ions permeate the electrolyte 1 and move to the cathode side and reach the catalytic reaction layer 2C. Oxygen in the oxidant gas such as air diffuses in the diffusion layer 3C and reaches the catalytic reaction layer 2C. In the catalytic reaction layer 2C, oxygen reacts with electrons to form oxygen ions, and the oxygen ions react with hydrogen ions to generate water. That is, oxygen-containing gas and fuel gas react around MEA 5 to generate water, and electrons flow. Further, heat is generated during the reaction, and the temperature of MEA 5 rises. Therefore, the heat generated in the reaction is carried out by water by flowing water or the like through the cooling water paths 8a and 8c. That is, heat and current (electricity) are generated. At this time, it is important to control the humidity of the introduced gas and the amount of water generated by the reaction. When there is little moisture, the electrolyte 1 is dried and the ionization of the fixed charge is reduced, so that the movement of hydrogen is reduced, so that the generation of heat and electricity is reduced. On the other hand, when there is too much moisture, water accumulates around the MEA 5 or around the catalyst reaction layers 2a and 2c, and the gas supply is inhibited and the reaction is suppressed, so that the generation of heat and electricity is reduced ( Hereinafter, this state is referred to as flatting).

  The operation after reacting in the fuel cell will be described with reference to FIG. The exhaust gas, which is an oxidant gas that has not been used in the stack 38, is transferred to the oxidant gas sent from the blower 39 via the humidifier 41 and then discharged to the outside. Off-gas that is fuel gas that has not been used in the stack 38 flows again into the fuel generator 35 through the off-gas pipe 48. The gas from the off gas pipe 48 is used for combustion in the fuel generator 35. Since the reaction for generating the fuel gas from the raw material gas is an endothermic reaction as shown by (Chemical Formula 6), it is used as heat necessary for the reaction. The power circuit 43 serves to draw DC power from the stack 38 after the fuel cell starts generating power. The controller 44 controls the other parts of the fuel cell system so as to keep the control optimal. In order to stop the operation of the fuel cell, the distribution valve 56 and the distribution valve 60 are operated, and the raw material gas purified by the gas purification unit 32 is poured into the stack 38.

  In the present embodiment, in FIG. 1, the MEA 5 is created as follows. In other words, carbon powder acetylene black (Denka Black manufactured by Denki Kagaku Kogyo Co., Ltd., particle size 35 nm) was mixed with an aqueous dispersion of polytetrafluoroethylene (PTFE) (D1 manufactured by Daikin Kogyo Co., Ltd.). A water repellent ink containing 20% by weight of PTFE as a dry weight was prepared. This ink is applied and impregnated on carbon paper (TGPH060H manufactured by Toray Industries, Inc.) serving as a base material for the gas diffusion layer, heat treated at 300 ° C. using a hot air dryer, and the gas diffusion layer (about 200 μm). ) Was formed.

  On the other hand, 66 parts by weight of a catalyst body (50 wt% Pt) obtained by supporting a Pt catalyst on Ketjen Black (Ketjen Black EC, Ketjen Black International Co., Ltd., particle size 30 nm), which is carbon powder. Is mixed with 33 parts by weight (polymer dry weight) of perfluorocarbon sulfonic acid ionomer (5% by weight Nafion dispersion manufactured by Aldrich, USA) which is a hydrogen ion conductive material and a binder, and the resulting mixture is molded. Thus, a catalyst layer (10 to 20 μm) was formed.

  The gas diffusion layer and the catalyst layer obtained as described above were bonded to both surfaces of a polymer electrolyte membrane (Nafion 112 membrane manufactured by DuPont, USA) to produce MEA5.

  Next, a rubber gasket plate was joined to the outer periphery of the electrolyte 1 of the MEA 5 produced as described above, and manifold holes for circulating cooling water, fuel gas, and oxidant gas were formed.

  On the other hand, a conductive separator plate 7 made of a graphite plate impregnated with a phenol resin, having an outer dimension of 20 cm × 32 cm × 1.3 mm and having a gas flow path and a cooling water flow path having a depth of 0.5 mm. Using.

  The operation of the fuel cell system of the present embodiment having the above-described configuration will be described below, and the flowchart of FIG. 4 shows an embodiment of the fuel cell system stop method of the present invention. explain. In the present embodiment, the raw material gas cleaned by the gas cleaning unit 32 is used as the inert gas. Since the main component of the source gas is methane gas, the polymer electrolyte fuel cell used in the present embodiment has almost no reactivity and can be treated as an inert gas.

First, power generation and heat generation (operation process) were performed in the fuel cell system of FIG. In (operation process), 13A gas of city gas was used as the source gas, and air was used as the oxidant gas. The temperature of the fuel cell stack 38 was 70 ° C., the fuel gas utilization rate (Uf) was 70%, and the oxygen utilization rate (Uo) was 40%. The fuel gas and air were humidified so as to have dew points of 65 ° C. and 70 ° C., respectively, and a current of a certain voltage was taken out from the power circuit unit 43 as power. The current was adjusted to a current density of 0.2 A / cm ^{2 with} respect to the apparent area of the electrode. Although not shown in the cooling water inlet pipe 46 and the cooling water outlet pipe 47, the temperature of the water in the cooling water inlet pipe 46 to which the hot water storage tank is attached is 70 ° C., and the temperature of the water in the cooling water outlet pipe 47. The pump 45 was adjusted to 75 ° C.

  The other conditions were as follows. The (operation process) was followed by (stop process 1).

  In (stop process 1), first, power generation of the stack 38 is stopped, and then the on-off valve 49 is closed to stop the supply of fuel gas to the stack 38, or the blower 39 is stopped simultaneously with the stop of supply of fuel gas to the stack. The distribution valve 60 allows all the purified fuel gas to flow to the bypass pipe 55, and the distribution valve 57 adjusts the gas flowing into the stack 38 so that the gas from the bypass pipe 55 is all. As a result, the oxidant gas is replaced with the raw material gas as the inert gas.

  Next, FIG. 7 shows a more specific flowchart of (stop step 1).

  As shown in FIG. 7, first, control is performed so that power from the stack 38 is not supplied to an external load (not shown) (S1), and then the on-off valve 49 is closed so that no more fuel gas is supplied to the stack 38 ( S2). After the on-off valve 49 is closed, the on-off valve 51 is closed (S3). Next, before the blower 39 is stopped, the on-off valve 57 is closed so that the oxidant gas is no longer supplied to the stack 38 (S4).

  Next, the distribution valves 60 and 56 are switched so that the raw material gas pipe 33 is switched from the clean gas pipe 36 side to be connected to the bypass pipe 55 and the oxidant gas pipe 40a, and then the on-off valve 57 is opened (S5). As a result, the raw material gas that has passed through the gas cleaning unit 32 is supplied to the cathode side of the stack 38, and the oxidizing gas in the stack 38 is purged by this raw material gas. Here, the control unit 44 measures the supply amount of the supplied source gas (S6), and determines whether or not the value is equal to or greater than a predetermined value (S7). The supply of the source gas is continued until this value is reached. If it is determined that the value is equal to or greater than the value, the on-off valve 57 is closed (S8), and then the on-off valve 58 is closed (S9). Next, the pump 45 is stopped and the cooling water circulation to the stack 38 is stopped (S10).

  In the operation of S7 described above, as a predetermined value, the supply amount of the source gas to be replaced is 2 to 5 times the volume to be replaced. This is based on the following calculation.

If the volume to be replaced is V (L), the flow rate of the gas to be replaced is v (L / min), the initial concentration of the target component of the oxidant gas is c _o , and the concentration after t (min) time is c, ( As represented by the calculation formula 1), the concentration change dc in the volume V during the minute time dt becomes equal to the amount of the target component pushed out by the replacement gas during the minute time dt.

  After multiplying both sides by −1, taking the logarithm of both sides gives (Calculation Formula 2).

  If it arranges, it will become (calculation formula 3), and it will become (calculation formula 4) if it integrates. Here, x is an integral constant.

  (Calculation Formula 4) can be rewritten as (Calculation Formula 5).

Here, when t = 0, c = _co , so when substituting into (Equation 5), (Equation 6) is obtained.

Therefore, (Calculation Formula 6) is substituted into (Calculation Formula 5) to be (Calculation Formula 7).

  In (Equation 7), v · t / V represents how many times the volume of the gas to be replaced is larger than the volume to be replaced. If double, 86% or more will be replaced, and if 5 times, 99.3% or more will be replaced. This is because if the volume of the replacement gas is 2 times or less, the remaining amount of the oxidant gas increases, and if it exceeds 5 times, the replacement gas is wasted. In (stop step 1), the supply of fuel gas is stopped earlier than or simultaneously with the stop of supply of oxidant gas, so that the power generation efficiency per fuel energy can be increased without wasting fuel gas. .

  After the above (stop process 1) is completed, the process proceeds to (stop process 2). That is, the valve 34 is closed and the supply of the raw material gas is stopped. It should be noted that the extraction of current from the stack 38 may be the same as the stop of the blower 39 in (stop process 1) as described above, but the power circuit unit 43 may be controlled with a predetermined voltage.

  In the present embodiment, when the voltage per unit cell of the stack 38 is 0.5 V or higher, the current is controlled by the power circuit unit 43, and when the voltage is less than 0.5 V, the current is not extracted. If stopped in (stop step 2), the catalytic reaction layer 2a is filled with a gas containing hydrogen, so the potential becomes (hydrogen electrode ratio) 0V. The catalyst reaction layer 2c is filled with a raw material gas which is an inert gas, but since hydrogen diffuses through the electrolyte 1, the potential becomes (hydrogen electrode ratio) 0V. Therefore, both electrodes can be stopped without becoming a high potential at which oxidation or dissolution occurs, so that there is little deterioration and the performance can be maintained for a long time.

  Further, the process proceeds to (stop process 3). That is, the on-off valve 62 that has been closed until the above (operation process) to (stop process 2) is opened, the on-off valve 51 is further opened, and the distribution valves 60 and 57 are connected to the bypass pipe 55 and the oxidant gas pipe. Switch to communicate with 40a. As a result, the raw material gas is supplied to the cathode side of the stack 38 and also supplied to the anode side through the bypass pipe 61. Next, the on-off valve 51 is closed again, and the valve 34 is closed. Thereby, the source gas is sealed inside the entire stack 38.

  In (stop process 3), changes in pressure gauges 59a and 59b are monitored. Since the on-off valves 49, 51, 57 and 58 are closed, the volume of the encapsulated source gas decreases when the humidity component in the encapsulated gas causes dew condensation or the like because the temperature of the stack 38 decreases. Then, the inside of the stack 38 becomes negative pressure. When the internal pressure of the stack 38 becomes negative, not only gas such as air is likely to enter, but the electrolyte 1 and various gaskets may be damaged. Therefore, when the values measured by the pressure gauges 59a and 59b change more than a certain value, the valve 34 is opened and the raw material gas is added. In this embodiment, the operation is performed when the pressure changes by 5 KPa. When the pressure inside the stack 38 becomes a predetermined value or less, the on-off valve 34 is opened and the source gas is filled again. When the raw material gas is added to the fuel gas, the hydrogen concentration decreases, but since the intrusion of a gas having a high potential such as oxygen is eliminated, the potentials of the electrodes 4a and 4c can be kept low. Thereby, not only deterioration due to electrode oxidation or dissolution can be suppressed, but also damage to the constituent material of the stack 38 due to pressure change can be prevented, so that high performance can be maintained for a long period of time.

  In the above description, the pressure gauges 59a and 59b have been described as directly measuring the pressure in the stack 38. However, a means such as a thermometer for measuring the temperature in the stack 38 is provided to obtain the pressure. Based on the measured value, the internal pressure of the stack 38 may be obtained indirectly. That is, when the difference ΔT is about 5 ° C. from the temperature T2 after the purge on the cathode side is completed to the temperature T2 at the time of measurement, it is considered that the pressure has dropped, the on-off valve 34 is opened, and the source gas is stacked again. Enclose in.

  Finally, after (stop process 3) continues for a predetermined time, it is determined whether or not to resume the operation. When the operation is resumed according to the DSS operation cycle, the operation returns to the (operation process) again. However, when the operation is not resumed for a reason such as not being used for a long period of time, the main power supply of the system is turned off.

  In the present embodiment, the raw material gas cleaned by the gas cleaning unit 32 is used as the inert gas. This is convenient because it uses a source gas and can be produced without a special device. However, the same effect can be obtained even if a nitrogen gas cylinder or the like is used and an inert gas such as nitrogen gas is used. Moreover, in this Embodiment, the raw material gas as an inert gas was humidified with the humidifier 41 provided in the passage of oxidant gas and fuel gas. By providing the humidifier 41 in the common passage path of the oxidant gas and the fuel gas, different gases can be humidified with one humidifier, which is more effective. Moreover, the source gas as an inert gas was humidified. Even if there is no humidification, if the volume supplied to the stack 38 is relatively small, the influence is slight. However, if the volume supplied is large, the electrolyte 1 is dried and the permeability of hydrogen ions is reduced. Humidified. Therefore, if the supplied volume is relatively small, humidification may be omitted.

  In the above configuration, the bypass pipe 61 and the on-off valve 62 may be omitted, and the stop process 3 may be omitted, and the stop process 3 may be performed by sealing the source gas only on the cathode side.

(Embodiment 2)
The operation of the fuel cell system according to the second embodiment will be described below, and an embodiment of the fuel cell system stopping method according to the present invention will be described below with reference to the flowchart shown in FIG. The basic configuration and operation are the same as those in the first embodiment. The detailed operation method is shown below. (Operation process) is the same as in the first embodiment.

  Next, (stop process 1) was performed. In (stop step 1), the blower 39 is first stopped, and the fuel gas after purification is caused to flow to both the bypass pipe 55 and the clean gas pipe 36 by the distribution valve 60, and the distribution valve 57 is switched to the stack 38. The gas flowing in is adjusted so that only the gas from the bypass pipe 55 is present.

  As a result, the fuel gas flows into the stack 38 and the oxidant gas in the stack 38 is replaced with the raw material gas as the inert gas. It moves after a predetermined time (stop process 2).

  In (stop process 2), the on-off valves 57 and 58 are closed, and a raw material gas as an inert gas is sealed inside the stack 38. In (stop process 2), since fuel gas is supplied, hydrogen is also supplied. Since the source gas is sealed, the hydrogen that diffuses the electrolyte 1 from the fuel gas and moves to the source gas side stays in the vicinity of the catalyst reaction layer 2c. As a result, the potential of the electrode 4c can be lowered more quickly and reliably, so that deterioration of the electrode can be suppressed more reliably. (Stop process 2) may be performed for a predetermined time, but in the present embodiment, after the voltage per unit cell of the stack becomes 0.1 V or less, the process proceeds to (stop process 3). In the (stop process 2) of the present embodiment, the electrode 4a is always 0 V, so the cell voltage is equal to the potential of the electrode 4c. When the electrode 4c becomes 0.1V, it can be said that the potential of the electrode 4c is surely lowered by the diffused hydrogen, and the fuel gas can be used without excess or deficiency, so that the power generation efficiency per energy is increased.

  In the next (stop process 3), the on-off valves 49 and 51 are closed and the fuel gas is sealed in the stack 38. In the present embodiment, the fuel gas and the raw material gas are sealed in the stack 38 by closing the on-off valves 49 and 51. Therefore, in the state of (stop process 3), gas does not enter or exit by convection or the like. 4c can be maintained at a low potential, and therefore, deterioration due to oxidation and dissolution is less, so that the performance can be maintained for a longer period of time.

  Further, the process proceeds to (stop process 4). The stack 38 does not enter or exit from the outside due to gas convection or the like due to the on-off valves 49, 51, 57 and 58, but oxygen or the like slightly diffuses from the outside. Therefore, the raw material gas cleaned by the gas cleaning unit 32 is caused to flow to both the bypass pipe 55 and the clean gas pipe 36 by the distribution valve 60 at regular intervals. Here, the on-off valves 57 and 58 are slightly opened, the raw material gas that has passed through the bypass building 55 is sent to the stack 38, and is slightly replaced with the sealed gas. The raw material gas that has passed through the clean gas pipe 36 is sent to the fuel generator 35. By selecting a certain time so that the fuel generator 35 does not react with the temperature or temperature, the raw material gas remains as it is. Can be passed. Here, the on-off valves 49 and 51 are slightly opened, and the sealed fuel gas is slightly replaced with the raw material gas. As a result, the gas concentration of oxygen or the like that has entered from the outside during sealing can be reduced, and the potential increase of the electrodes 4a and 4c can be suppressed for a long period of time. Deterioration due to oxidation or dissolution can be suppressed, and long-term performance can be maintained. In the above configuration, the bypass pipe 61 and the on-off valve 62 may be omitted.

(Embodiment 3)
The operation of the fuel cell system according to the third embodiment will be described below, and an embodiment of the method for stopping the fuel cell system according to the present invention will be described below with reference to the flowchart shown in FIG. The basic configuration and operation are the same as those of the first or second embodiment, but the bypass pipe 61 and the on-off valve 62 are omitted.

  The detailed operation method is shown below. The basic conditions for power generation and heat generation (operation process) are the same as those in the first embodiment. Here, the current drawn from the stack 38 by the power circuit unit 43 is controlled by the control unit 44 in accordance with the amount of power consumed at home or the like. When the electric power generated from the fuel cell system is not consumed, the current drawn from the stack 38 decreases, and the voltage rises. When the voltage exceeds the open circuit voltage of 0.88 V, oxidation and dissolution of the electrode 4c occur, and the process proceeds to (stop process 1). That is, the operation in a state where the voltage exceeds the open circuit voltage 0.88 V can be eliminated, so that the performance can be maintained for a long time.

  (Stop process 1) is the same as that of the first embodiment. First, the blower 39 is stopped, and the fuel gas after purification is caused to flow to both the bypass pipe 55 and the clean gas pipe 36 by the distribution valve 60, and distributed. The gas flowing into the stack 38 by the valve 57 is adjusted so that the gas from the bypass pipe 55 is all. As a result, the fuel gas flows into the stack 38 and the oxidant gas in the stack 38 is replaced with the raw material gas as the inert gas.

  It moves after a predetermined time (stop process 2). In (stop process 2), the on-off valves 49 and 51 are closed while the raw material gas is flowing even after the purge is completed, and the fuel gas is sealed in the stack 38. Thereby, the use of fuel gas can be reduced. Further, the process proceeds to (stop process 3). The on-off valves 57 and 58 are closed, and a raw material gas as an inert gas is sealed inside the stack 38. The hydrogen that has diffused the electrolyte 1 from the fuel gas and moved to the raw material gas in the stack 38 stays in the vicinity of the catalytic reaction layer 2c. Thereby, since the electric potential of the electrode 4c can be lowered reliably, the deterioration of the electrode can be reliably suppressed. In the state of (stopping step 3), gas does not enter or exit due to convection, etc., so the potentials of the electrodes 4a and 4c can be kept low, so that deterioration due to oxidation and dissolution is small, so long-term performance can be maintained. is there. Further, the process proceeds to (stop process 4).

  In (stop process 4), changes in pressure gauges 59a and 59b are monitored. Since the on-off valves 49, 51, 57 and 58 are closed, the volume of the encapsulated source gas decreases when the humidity component in the encapsulated gas causes dew condensation or the like because the temperature of the stack 38 decreases. Then, the inside of the stack 38 becomes negative pressure. When the internal pressure of the stack 38 becomes negative, not only gas such as air is likely to enter, but the electrolyte 1 and various gaskets may be damaged. Therefore, when the values measured by the pressure gauges 59a and 59b change more than a certain value, the on-off valve 49 or 57 is opened to add the raw material gas. In this embodiment, the operation is performed when the pressure changes by 5 KPa. The operation of flowing the raw material gas through the stopped stack 38 is the same as in the second embodiment. When the pressure inside the stack 38 reaches a predetermined value, the on-off valve 49 or 57 is opened and the gas is sealed again. When the raw material gas is added to the fuel gas, the hydrogen concentration decreases, but since the intrusion of a gas having a high potential such as oxygen is eliminated, the potentials of the electrodes 4a and 4c can be kept low. Thereby, not only deterioration due to electrode oxidation or dissolution can be suppressed, but also damage to the constituent material of the stack 38 due to pressure change can be prevented, so that high performance can be maintained for a long period of time.

  In the above description, the pressure gauges 59a and 59b have been described as directly measuring the pressure in the stack 38. However, a means such as a thermometer for measuring the temperature in the stack 38 is provided to obtain the pressure. Based on the measured value, the internal pressure of the stack 38 may be obtained indirectly. That is, when the difference ΔT is about 5 ° C. from the temperature T1 after the cathode side purge is completed to the temperature T2 at the time of measurement, it is considered that the pressure has decreased, and the on-off valve 49 or 57 is opened, and the source gas is again supplied. Enclose in the stack 38.

  In the first to third embodiments, the stack 38 corresponds to the fuel cell of the present invention, the fuel gas pipe 37 corresponds to the fuel gas pipe of the present invention, and the on-off valve 49 corresponds to the fuel gas on-off valve of the present invention. These constitute the fuel gas supply means of the present invention. The oxidant gas pipe 40a corresponds to the oxidant gas pipe of the present invention, and the on-off valve 57 corresponds to the oxidant on-off valve of the present invention, and these constitute the oxidant gas supply means of the present invention. The source gas pipe 33 and the bypass pipe 55 correspond to the source gas pipe of the present invention, the distribution valves 56 and 60 correspond to the source gas on / off valve of the present invention, and these correspond to the source gas supply means of the present invention. The control unit 44 corresponds to the control means of the present invention.

  The off-gas pipe 48 corresponds to the anode-side exhaust pipe of the present invention, the on-off valve 51 corresponds to the anode-side off-gas on-off valve of the present invention, and the exhaust pipe 42 corresponds to the cathode-side exhaust pipe of the present invention. 58 corresponds to the anode-side off-gas on-off valve of the present invention. The bypass pipe 61 corresponds to the additional source gas pipe of the present invention, and the on-off valve 62 corresponds to the additional source gas on-off valve of the present invention.

  The above first to third embodiments may correspond to the following embodiments of the invention. That is, as a first invention, a polymer electrolyte membrane, a pair of electrodes sandwiching the polymer electrolyte membrane, and a fuel gas containing at least hydrogen at one of the electrodes is supplied and discharged, and an oxidant gas containing oxygen at the other A fuel cell having a pair of separators having gas flow paths for supplying and discharging gas, a fuel generator for generating fuel gas to be supplied from the source gas to the fuel cell, and components that adversely affect the fuel cell from the source gas In a fuel cell system having a gas cleaning unit to be removed, a power circuit unit that extracts power from the fuel cell, a voltage measurement unit that measures the voltage of the fuel cell, and a control unit that controls the gas and the power circuit unit, etc. When the battery is stopped, the supply of the fuel gas and the oxidant gas is stopped, and the oxidant gas inside the fuel cell is partially or entirely replaced with an inert gas to the fuel cell. As a result, there is no oxygen in the stopped fuel cell or there is little oxygen, so the anode electrode has a hydrogen potential (hydrogen electrode reference of about 0 V), and the cathode electrode also diffuses from the anode. Since the potential of hydrogen is brought about by hydrogen and the potential of both electrodes can be kept low, it is possible to suppress performance degradation due to stoppage.

  Further, as the second invention, in particular, the fuel cell system of the first invention is provided with a shutoff valve in the supply path and the discharge path of the fuel gas and the oxidant gas, and when the fuel cell is stopped, the fuel gas and the oxidant gas The supply is stopped, the oxidant gas inside the fuel cell is partially or completely replaced with a gas inert to the fuel cell, the shut-off valve is closed, and the fuel gas and the gas inert to the fuel cell are fueled. Since the fuel cell system that can be enclosed in the battery shuts off the flow of gas inside and outside the fuel cell while it is stopped, the potential of the electrode of the fuel cell is kept low even if it is stopped for a long time. Therefore, it is possible to suppress the performance degradation due to the stop.

  As the third invention, in particular, the fuel cell system of the first invention or the second invention is provided with a humidifier in the passage of the oxidant gas and the raw material gas, and the humidified oxidant gas and the raw material gas are supplied to the fuel cell. When the raw material gas from which the components that adversely affect the fuel cell are removed in the gas cleaning section is used as an inert gas that replaces part or all of the oxidant gas Since the raw material gas can be flown into the fuel cell and the polymer electrolyte membrane can be prevented from being dried, the deterioration of the performance due to the drying of the polymer electrolyte membrane that occurs during the stop can be suppressed.

  Further, as a fourth invention, a polymer electrolyte membrane, a pair of electrodes sandwiching the polymer electrolyte membrane, and a fuel gas containing at least hydrogen at one of the electrodes is supplied / discharged, and an oxidant gas containing oxygen at the other A fuel cell having a pair of separators having gas flow paths for supplying and discharging gas, a fuel generator for generating fuel gas to be supplied from the source gas to the fuel cell, and components that adversely affect the fuel cell from the source gas In a fuel cell system having a gas cleaning unit to be removed, a power circuit unit that extracts power from the fuel cell, a voltage measurement unit that measures the voltage of the fuel cell, and a control unit that controls the gas and the power circuit unit, etc. When the voltage of the fuel cell exceeds 0.88 V when the battery is stopped, the supply of the fuel gas and the oxidant gas is stopped, and the oxidant gas inside the fuel cell is partially or inactive to the fuel cell. By making the operation method of the fuel cell system to replace the part, the potential of each electrode of the fuel cell can always be 0.88 V or less (on the basis of the hydrogen electrode), thereby preventing oxidation and dissolution of a catalyst such as Pt. Therefore, the performance can be maintained for a long time.

  Further, as a fifth invention, a polymer electrolyte membrane, a pair of electrodes sandwiching the polymer electrolyte membrane, and a fuel gas containing at least hydrogen at one of the electrodes is supplied and discharged, and an oxidant gas containing oxygen at the other A fuel cell having a pair of separators having gas flow paths for supplying and discharging gas, a fuel generator for generating fuel gas to be supplied from the source gas to the fuel cell, and components that adversely affect the fuel cell from the source gas In a fuel cell system having a gas cleaning unit to be removed, a power circuit unit that extracts power from the fuel cell, a voltage measurement unit that measures the voltage of the fuel cell, and a control unit that controls the gas and the power circuit unit, etc. When the battery is stopped, supply of fuel gas and oxidant gas is stopped at the same time, or after the fuel gas is stopped, the oxidant gas is stopped, and the oxidant gas inside the fuel cell is partially inert to the fuel cell. Alternatively, by operating the fuel cell system to replace the whole, the anode electrode is filled with hydrogen (hydrogen reference), so that the cathode electrode has a potential of about 0 V, and the cathode electrode reduces the pressure in the path or the inertia of the blower. Even if there is an oxidant gas supply due to, after replacing with an inert gas, the potential of the cathode electrode becomes about 0 V (on the basis of the hydrogen electrode) due to hydrogen diffusing from the anode. The decrease can be suppressed. Also, by stopping the fuel gas before the oxidant gas, the amount of hydrogen that is not used for power generation can be minimized, and a fuel cell system with higher power generation efficiency per energy can be realized.

  As a sixth invention, a polymer electrolyte membrane, a pair of electrodes sandwiching the polymer electrolyte membrane, and a fuel gas containing at least hydrogen is supplied to and discharged from one of the electrodes, and an oxidant gas containing oxygen is supplied to the other A fuel cell having a pair of separators having gas flow paths for supplying and discharging gas, a fuel generator for generating fuel gas to be supplied from the source gas to the fuel cell, and components that adversely affect the fuel cell from the source gas In a fuel cell system having a gas cleaning unit to be removed, a power circuit unit that extracts power from the fuel cell, a voltage measurement unit that measures the voltage of the fuel cell, and a control unit that controls the gas and the power circuit unit, etc. When the battery is stopped, the supply of the oxidant gas is stopped, and then the supply of the fuel gas is stopped. The oxidant gas inside the fuel cell is partially or completely replaced with a gas inert to the fuel cell. By operating the battery system, hydrogen flows to the anode at least for the first time when the cathode replaces the oxidant gas with an inert gas. Therefore, even if oxygen diffuses from the cathode to the anode, the anode electrode The potential is not changed at all (reference to the hydrogen electrode) and is maintained at about 0 V, and a sufficient amount of hydrogen diffuses to the cathode, so the potential of the cathode electrode should be quickly and reliably reduced to about 0 V (reference to the hydrogen electrode). Therefore, the performance of the cathode electrode can be reliably improved, so that the performance can be suppressed from being lowered even when the operation is stopped.

  Further, as a seventh invention, a polymer electrolyte membrane, a pair of electrodes sandwiching the polymer electrolyte membrane, and a fuel gas containing at least hydrogen at one of the electrodes is supplied and discharged, and an oxidant gas containing oxygen at the other A pair of separators having a gas flow path for supplying and discharging gas, a fuel cell having a shutoff valve in the fuel gas and oxidant gas supply path and discharge path, and a fuel gas to be supplied from the source gas to the fuel cell A fuel generator, a gas cleaning unit that removes components that adversely affect the fuel cell from the raw material gas, a power circuit unit that extracts power from the fuel cell, a voltage measurement unit that measures the voltage of the fuel cell, and a gas and power circuit In a fuel cell system having a control unit that controls the fuel cell, the supply of the fuel gas is stopped when the fuel cell is stopped, and then the fuel gas is sealed inside the fuel cell with a shut-off valve, and the oxidant gas After the supply is stopped and the oxidant gas inside the fuel cell is partially or completely replaced with an inert gas for the fuel cell, the inert gas is sealed with a shut-off valve, and after a certain time, the fuel gas sealing part And the operation method of the fuel cell system in which an inert gas is injected into the inert gas enclosure, the volume of the fuel cell is reduced due to condensation, contraction, or the reaction of oxygen and hydrogen that remains inside the fuel cell during shutdown. Even if the internal pressure is negative or the difference between the pressure of the anode and the cathode occurs, the internal pressure is negative or negative by injecting the inert gas into the fuel gas enclosure or the inert gas enclosure. Since the pressure difference between the anode and the cathode can be eliminated, the stress applied to the polymer electrolyte membrane or the like can be eliminated, so that a decrease in performance can be suppressed even if the operation is stopped. Further, when the inert gas is injected, the sealed gas can be replaced with the inert gas by opening the shutoff valve in the fuel gas or oxidant gas discharge path. Even if the oxygen in the air gradually enters through the gasket or the separator material while the fuel cell is stopped, it can be discharged to the outside of the fuel cell.

  As an eighth invention, a polymer electrolyte membrane, a pair of electrodes sandwiching the polymer electrolyte membrane, and a fuel gas containing at least hydrogen is supplied to and discharged from one of the electrodes, and an oxidant gas containing oxygen is supplied to the other. A pair of separators having a gas flow path for supplying and discharging gas, a fuel cell having a shutoff valve in the fuel gas and oxidant gas supply path and discharge path, and a fuel gas to be supplied from the source gas to the fuel cell A fuel generator, a gas cleaning unit that removes components that adversely affect the fuel cell from the source gas, a power circuit unit that extracts power from the fuel cell, a voltage measurement unit that measures the voltage of the fuel cell, and the interior of the fuel cell In a fuel cell system having a pressure measuring unit for measuring the pressure of the fuel and a control unit for controlling the gas and power circuit unit, the fuel gas is stopped when the fuel cell is stopped, and then the shut-off valve The fuel gas is sealed inside the fuel cell, the supply of the oxidant gas is stopped, and the oxidant gas inside the fuel cell is partially or completely replaced with a gas inert to the fuel cell and then inactivated by the shutoff valve. When the pressure inside the fuel cell changes more than a certain level, an inert gas is injected into the fuel gas enclosure and the inert gas enclosure or the shut-off valve is opened to open the space inside the fuel cell to the outside. By operating the fuel cell system, the gas inside the fuel cell is condensed, contracted, or the volume of the gas is reduced due to the reaction between oxygen and hydrogen during the stoppage, and the internal pressure is negative or Even if there is a difference in the pressure of the cathode, the internal pressure can be reliably eliminated by injecting inert gas into the fuel gas enclosure or inert gas enclosure. Can Since, it is possible to eliminate the stress on the polymer electrolyte membrane or the like, and can suppress a decrease in performance even if the stop. Furthermore, when the inert gas is injected, the sealed gas can be replaced with the inert gas by opening the shutoff valve in the fuel gas or oxidant gas discharge path, and the gasket and separator material can be replaced while the fuel cell is stopped. Even if oxygen in the air gradually enters through the air, it can be discharged to the outside of the fuel cell.

  As a ninth invention, a polymer electrolyte membrane, a pair of electrodes sandwiching the polymer electrolyte membrane, and a fuel gas containing at least hydrogen is supplied to and discharged from one of the electrodes, and an oxidant gas containing oxygen is supplied to the other. A pair of separators having a gas flow path for supplying and discharging gas, a fuel cell having a shutoff valve in the fuel gas and oxidant gas supply path and discharge path, and a fuel gas to be supplied from the source gas to the fuel cell A fuel cell having a fuel generator, a gas cleaning unit that removes components that adversely affect the fuel cell from the raw material gas, a power circuit unit that extracts power from the fuel cell, and a control unit that controls the gas and the power circuit unit In the system, when the fuel cell is stopped, the supply of the fuel gas is stopped, and then the fuel gas is sealed inside the fuel cell by the shutoff valve, the supply of the oxidant gas is stopped, and the oxidant gas inside the fuel cell is stopped. By supplying an inert gas to the fuel cell in the path, and after the fuel cell voltage reaches a predetermined voltage, an anode electrode is provided by operating the fuel cell system by sealing the inert gas with a shut-off valve. Can be reliably maintained at about 0V (on a hydrogen electrode basis), the voltage can detect the cathode potential, and can be reliably replaced with an inert gas until the cathode potential reaches a predetermined potential. Even if the operation is stopped, the performance degradation can be suppressed.

  According to the tenth invention, in particular, any of the first to ninth inventions is used as a gas inert to the fuel cell, and the raw material gas removed by the component gas cleaning unit that adversely affects the fuel cell is removed. By using the fuel cell system to be used or the operation method of the fuel cell system, it is possible to easily replace the oxidant gas with an inert gas without having a special device such as a cylinder. However, the performance degradation can be suppressed.

(Embodiment 4)
FIG. 8 is a configuration diagram of a fuel cell system according to Embodiment 4 of the present invention.

  A fuel cell system according to a fourth embodiment of the present invention includes a solid polymer fuel cell 81 that generates power using fuel gas and oxidant gas, and reforms the raw material gas by adding water to hydrogen. Combustion generator 82 that generates a rich fuel gas, water supply means 83 that supplies water to the fuel generator 82, a combustor 84 that combusts the fuel gas discharged from the fuel cell 81, and air as an oxidant gas Is supplied to the cathode of the fuel cell 81, purge air supply means 86, a fuel gas supply channel for supplying the fluid sent from the fuel generator 82 to the anode of the fuel cell 81, and the fuel generator 82. And a flow path switching means 88 for switching to a bypass pipe 87 for guiding the fluid delivered from the fuel cell to a path for supplying exhaust combustion gas to the combustor by bypassing the fuel cell, and residual fuel from the fuel cell 81 On-off valve 89 on the path through which gas is discharged, raw material cathode supply means 810 for supplying the raw material to the cathode of the fuel cell 81, the air inlet side from the blower 85 to the fuel cell 81, and the fuel cell 1. And cathode closing means 811 having an on-off valve for opening and closing the air outlet side. Here, the raw material is not limited to natural gas, but includes a compound composed of at least carbon and hydrogen, exemplified by city gas, hydrocarbons such as methane and propane, and alcohols such as methane and ethanol. Any material can be used. However, the liquid raw material such as alcohol is preferably a vaporized raw material gas.

  In addition, when the flow path switching unit 88 forms a bypass flow path and is set to supply the fluid sent from the fuel generator 82 to the bypass pipe 87, the fuel gas inlet side to the fuel cell 81 is closed. Therefore, the flow path switching means 88 and the on-off valve 89 constitute an anode closing means 812. The internal configuration of the fuel cell 81 is the same as that shown in FIGS.

  The operation of the fuel cell system according to the present embodiment having the above-described configuration will be described below, and an embodiment of the method for stopping the fuel cell system according to the present invention will be described.

  During the operation of the fuel cell system, the fuel generator 82 is maintained at a temperature of about 640 ° C. to generate a fuel gas rich in hydrogen from natural gas and water, and the fuel gas is a channel switching that forms a supply channel. It is sent to the fuel cell 81 via the means 88. In the fuel cell 81, power generation is performed using hydrogen in the fuel gas and oxygen in the air supplied from the blower 85 via the open cathode closing means, and the remaining fuel gas not consumed in the power generation is released. It is sent to the combustor 84 through the open / close valve 89 and burned, and used as a heat source for maintaining the temperature of the fuel generator 82.

  When the fuel cell system stops power generation, the blower 85 is stopped to stop air supply to the cathode of the fuel cell 81, and before the voltage of the fuel cell 81 becomes an open circuit voltage, the raw material cathode supply means 810 Starts supplying the raw material to the cathode of the fuel cell 81. When the raw material expels almost all the air in the cathode of the fuel cell 81, the cathode closing means 811 is closed, and the raw material cathode supply means 810 stops supplying the raw material to the cathode of the fuel cell 81.

  Further, the flow path switching means 88 is switched to the bypass pipe 87 side to form a bypass flow path and close the on-off valve 89, thereby sealing the fuel gas present at the anode of the fuel cell 81 and generating fuel. The supply of the raw material to the vessel 82 is stopped.

  On the other hand, the supply of water to the fuel generator 82 by the water supply means 83 is continued. The water supplied to the fuel generator 82 is converted into water vapor by the heat of the fuel generator 82, and the hydrogen-rich fuel gas remaining in the fuel generator 82 is pushed out via the flow path switching means 88 and the bypass pipe 87. Combustion is performed by the combustor 84. Thereafter, the amount of the fuel gas rich in hydrogen gradually decreases, so that the combustion in the combustor 84 is stopped, but the generation of water vapor is continued by the residual heat of the fuel generator 82.

  When the amount of water vapor generated in the fuel generator 82 reaches the amount enough to drive out the hydrogen-rich fuel gas in the fuel generator 82, and the temperature of the fuel generator 82 has dropped to about 400 ° C., water supply Water supply by the means 83 is stopped and air is supplied by the purge air supply means 86 to push out water vapor in the fuel generator 82 from the combustor 84 via the flow path switching means 88 and the bypass pipe 87. Discharge. When the water vapor in the fuel generator 82 and each part of the pipe is driven out, the purge air supply means 86 stops the supply of air and completes the stop process of the fuel cell system.

  The temperature of 400 ° C. assumes that the catalyst used in the fuel generator 82 is mainly composed of ruthenium. In order to prevent the catalyst from being oxidized by touching air at a high temperature, a certain degree of deterioration is caused. The temperature is set in anticipation of the safety factor. Therefore, it is natural that the temperature changes depending on the setting of the safety factor, and the temperature should naturally be set differently if the type of the catalyst is different.

  Next, when starting the fuel cell system, the flow path switching means 88 supplies the raw material to the combustor 84 via the fuel generator 82, the flow path switching means 88, and the bypass pipe 87 while the bypass flow path is formed. And burn. At the same time, the water supply means 3 supplies water to the fuel generator 82. Then, the fuel generator 82 is heated to about 640 ° C. by the combustor 84, and the raw material is converted into a fuel gas rich in hydrogen. The temperature of the carbon monoxide removal unit (not shown) included in the fuel generator 82 is stabilized and the concentration of carbon monoxide included in the fuel gas does not deteriorate the anode electrode of the fuel cell 81 (about 20 ppm). When the voltage drops, the on-off valve 89 is opened, the flow path switching means 88 is switched to the fuel gas supply flow path side, and the fuel gas is passed to the combustor 84 via the flow path switching means 88, the fuel cell 81, and the on-off valve 89. Supply.

  At the same time, the cathode closing means 811 is opened, and the blower 85 starts supplying air to the cathode of the fuel cell 81 and starts power generation in the fuel cell 81.

  As described above, according to the present embodiment, when the fuel cell system is stopped, the flow path switching means 88 forms the bypass flow path and closes the on-off valve 89, as in the first to third embodiments. By enclosing the fuel gas in the anode of the fuel cell 1, even when nitrogen is not used, the fuel cell 81 can be safely stopped without flowing air into the cathode of the fuel cell 1. Never be exposed to. Further, since the raw material cathode supply means 810 supplies the raw material to the cathode of the fuel cell 1 and expels cathode air and then stops, gas diffusion from the cathode to the anode occurs through the polymer electrolyte membrane in the fuel cell 81. However, since air does not enter the anode, the anode potential is kept low, the anode catalyst is not eluted, and the durability of the fuel cell system is not reduced.

  In addition, since the cathode air discharge operation with the above-described raw material is started before the fuel cell 81 reaches the open circuit voltage, the cathode catalyst is not eluted due to the high cathode potential, and the durability of the fuel cell system is lowered. No.

  Further, by closing the cathode closing means 811, the raw material supplied to the cathode of the fuel cell 81 by the raw material cathode supply means 810 is sealed, so that air from the outside to the fuel cell 81 even if the stop period becomes longer. There is no risk that the fuel cell system will be lowered in durability, including during long-term shutdown.

  On the other hand, the fuel generator 82 first pushes out the internal fuel gas with water vapor and expels the water vapor with air after the temperature has dropped sufficiently, so there is no danger of flammable gas staying inside under high temperature conditions, and it stops Sometimes water does not stay inside, so that the water does not accumulate in the piping at the next start-up, and the fuel gas supply does not become unstable.

  At the time of start-up, after the combustion in the combustor 84 is started, the flow path switching means 88 is switched to the fuel gas supply flow path side, the on-off valve 89 is opened, and the fuel gas sealed in the fuel cell 1 is removed by the combustor 84. By burning, the fuel gas enclosed in the fuel cell 81 is not released to the outside, and there is no risk of the fuel gas being discharged to the outside.

(Embodiment 5)
FIG. 9 is a configuration diagram of a fuel cell system according to Embodiment 5 of the present invention. The same components as those in the conventional example or the fourth embodiment of the present invention are given the same numbers.

  The fuel cell system according to Embodiment 5 of the present invention is different from Embodiment 4 in that it further includes a material anode supply means 813 for supplying a material to the anode of the fuel cell 1.

  The operation of the fuel system of the present embodiment having the above-described configuration will be described below, and an embodiment of the fuel cell system stop method of the present invention will be described.

  During the operation of the fuel cell system, the fuel generator 82 is maintained at a temperature of about 640 ° C. to generate a fuel gas rich in hydrogen from natural gas and water, and the fuel gas is a channel switching that forms a supply channel. It is sent to the fuel cell 81 via the means 88. In the fuel cell 81, power generation is performed using hydrogen in the fuel gas and oxygen in the air supplied from the blower 85 via the open cathode closing means, and the remaining fuel gas not consumed in the power generation is released. It is sent to the combustor 84 through the open / close valve 89 and burned, and used as a heat source for maintaining the temperature of the fuel generator 82.

  When the fuel cell system stops power generation, first, the blower 85 is stopped to stop the air supply to the cathode of the fuel cell 81, and the raw material cathode supply is performed before the voltage of the fuel cell 81 becomes an open circuit voltage. The means 810 starts supplying the raw material to the cathode of the fuel cell 81. When the raw material expels almost all the air in the cathode of the fuel cell 81, the cathode closing means 811 is closed, and the raw material cathode supply means 810 stops supplying the raw material to the cathode of the fuel cell 81.

  Next, the flow path switching means 88 is switched to the bypass pipe 87 side to form a bypass flow path and keep the on-off valve 89 open, and the anode closing means 812 supplies the raw material to the anode of the fuel cell 1. . When the raw material expels almost all the fuel gas in the anode of the fuel cell 81, the on-off valve 89 is closed, and the raw material anode supply means 813 stops supplying the raw material to the anode of the fuel cell 81.

  On the other hand, the supply of the raw material to the fuel generator 82 is stopped, and the supply of water to the fuel generator 82 by the water supply means 83 is continued. The water supplied to the fuel generator 82 is converted into water vapor by the heat of the fuel generator 82, and the hydrogen-rich fuel gas remaining in the fuel generator 82 is pushed out via the flow path switching means 88 and the bypass pipe 87. Combustion is performed by the combustor 84. After that, the amount of the fuel gas rich in hydrogen gradually decreases, so that the combustion in the combustor 84 is stopped, but the generation of water vapor is continued by the residual heat of the fuel generator 82.

  When the amount of water vapor generated in the fuel generator 82 reaches the amount enough to expel the hydrogen-rich fuel gas in the fuel generator 2 and the temperature of the fuel generator 82 drops to about 400 ° C., water supply Water supply by the means 83 is stopped and air is supplied by the purge air supply means 86 to push out water vapor in the fuel generator 82 from the combustor 84 via the flow path switching means 88 and the bypass pipe 87. Discharge. When the water vapor in the fuel generator 82 and each part of the pipe is driven out, the purge air supply means 86 stops the supply of air and completes the stop generation of the fuel cell system.

  The temperature of 400 ° C. assumes that the catalyst used in the fuel generator 82 is mainly composed of ruthenium. In order to prevent the catalyst from being oxidized by touching air at a high temperature, a certain degree of deterioration is caused. The temperature is set in anticipation of the safety factor. Therefore, it is natural that the temperature changes depending on the setting of the safety factor, and the temperature should naturally be set differently if the type of the catalyst is different.

  Next, when starting the fuel cell system, the flow path switching means 88 supplies the raw material to the combustor 84 via the fuel generator 82, the flow path switching means 88, and the bypass pipe 87 while the bypass flow path is formed. Burn. At the same time, the water supply means 83 supplies water to the fuel generator 82. Then, the fuel generator 82 is heated to about 640 ° C. by the combustor 84, and the raw material is converted into a fuel gas rich in hydrogen. The temperature of the carbon monoxide removal section (not shown) included in the fuel generator 82 is stabilized, and the concentration of carbon monoxide included in the fuel gas does not deteriorate the anode electricity of the fuel cell 1 (about 20 ppm). When the voltage drops, the on-off valve 89 is opened, the flow path switching means 8 is switched to the fuel gas supply flow path side, and the fuel gas is transferred to the combustor 84 via the flow path switching means 88, the fuel cell 81, and the on-off valve 89. Supply.

  At the same time, the cathode closing means 811 is opened, and the blower 85 starts supplying air to the cathode of the fuel cell 81 and starts power generation in the fuel cell 81.

  As described above, when the fuel cell system is stopped, the anode closing means 812 supplies the raw material to the anode of the fuel cell 81, and when the raw material expels almost all the fuel gas in the anode of the fuel cell 81, the on-off valve 89 By sealing the raw material in a closed state, even when nitrogen is not used, air can be safely stopped without flowing into the cathode of the fuel cell 1, so that the anode of the fuel cell 1 is exposed to an oxygen-containing oxidizing atmosphere. There is nothing.

  Furthermore, since the raw material cathode supply means 810 supplies the raw material to the cathode of the fuel cell 81 at the beginning when power generation is stopped and drives off the cathode air, the fuel cell 81 is in a solid polymer form and is made of a solid polymer. Even if gas diffusion from the cathode to the anode occurs through the electromembrane, air is not mixed into the anode, so that the durability of the fuel cell system is not lowered. In addition, since the cathode air discharge operation by the above-described raw material is started before the fuel cell 81 reaches the open circuit voltage, a high potential difference is generated between the cathode and the anode of the fuel cell 1, and the electrode due to the weak current flowing. Elution does not occur, and the durability of the fuel cell system is not reduced.

  Further, by closing the cathode closing means 811, the raw material supplied to the cathode of the fuel cell 81 by the raw material cathode supply means 810 is sealed, so that air from the outside to the fuel cell 81 even if the stop period becomes longer. There is no risk that the fuel cell system will be lowered in durability, including during long-term shutdown.

  On the other hand, the fuel generator 82 first pushes out the internal fuel gas with water vapor and expels the water vapor with air after the temperature has dropped sufficiently, so there is no danger of flammable gas staying inside under high temperature conditions, and it stops Sometimes water does not stay inside, so that the water does not accumulate in the piping at the next start-up, and the fuel gas supply does not become unstable.

  At the time of start-up, after the combustion in the combustor 84 is started, the flow path switching means 88 forms a fuel gas supply flow path and opens the on-off valve 89 so that the fuel gas sealed in the fuel cell 1 is removed by the combustor 84. By burning, the fuel gas enclosed in the fuel cell 81 is not released to the outside, and there is no risk of the fuel gas being discharged to the outside.

  In the above fourth to fifth embodiments, the fuel cell 81 corresponds to the fuel cell of the present invention, and the fuel generator 82 corresponds to the fuel generator of the present invention. The pipe connecting the fuel generator 82 and the fuel cell 81 corresponds to the fuel gas pipe of the present invention, the flow path switching means corresponds to the fuel gas on-off valve of the present invention, and these are the fuel gas supply means of the present invention. Configure. The on-off valve on the air inlet side of the cathode closing means 811 corresponds to the oxidant gas on-off valve of the present invention, and the pipe connecting this to the fuel cell corresponds to the oxidant gas pipe of the present invention. The oxidant gas supply means of the invention is constituted.

  The raw material cathode supply means corresponds to the raw material gas on-off valve of the present invention, and the pipe connecting this to the fuel cell 81 corresponds to the raw material gas pipe of the present invention, and these constitute the raw material gas supply means of the present invention. .

  The on / off valve 89 on the fuel gas outlet side of the anode closing means 812 corresponds to the anode off-gas on / off valve of the present invention, and the pipe connecting this to the fuel cell corresponds to the anode discharge pipe of the present invention. The on-off valve 89 on the air outlet side of the cathode closing means 811 corresponds to the cathode-side off-gas on-off valve of the present invention, and the pipe connecting this to the fuel cell corresponds to the cathode-side exhaust pipe of the present invention.

  The bypass pipe 87 corresponds to the bypass means of the present invention, and the combustor 84 corresponds to the combustor of the present invention.

  It is to be noted that, by using the raw material anode supply means 813 as the additional raw material gas on-off valve of the present invention and the pipe connecting the raw material anode supply means 813 and the fuel cell 81 as the additional raw material gas pipe of the present invention, Embodiment 4 In the configuration of 5, the stop step 3 of the first embodiment may be performed.

  Further, the above fourth and fifth embodiments correspond to the following embodiments of the invention. That is, as a first invention, a fuel cell that generates power from a fuel gas containing hydrogen and an oxidant gas, a fuel generator that generates the fuel gas from a raw material, and a purge that supplies air to the fuel generator Air supply means, raw material cathode supply means for supplying raw materials to the cathode of the fuel cell, bypass means for bypassing the fuel cell on a fuel gas path from the fuel generation means to the fuel cell, and the fuel generator And a switching means for switching the path of the gas discharged from the fuel gas path or the Pibus means, and an anode closing means for closing the inlet and the outlet of the anode of the fuel cell, and stops the power generation of the fuel cell In this case, the raw material cathode supply means supplies the raw material to the cathode of the fuel cell, and the anode closing means has an inlet and an outlet of the anode. Sealed, and the switching to the bypass means side by the switching means, after supplying water by the water supply means, to supply the air may be a fuel cell system characterized by the purge air supply means.

  Further, as a second invention, a fuel cell that generates electric power from a fuel gas containing hydrogen and an oxidant gas, a fuel generator that generates the fuel gas from a raw material, and water that supplies water to the fuel generator Supply means; purge air supply means for supplying air to the fuel generator; raw material cathode supply means for supplying raw material to the cathode of the fuel cell; and raw material anode supply means for supplying raw material to the anode of the fuel cell; The bypass means for bypassing the fuel cell on the fuel gas path from the fuel generating means to the fuel cell, and the path of the gas discharged from the fuel generator is switched to either the fuel gas path or the pie bus means. Switching means, and when the power generation of the fuel cell is stopped, the raw material cathode supply means supplies the raw material to the cathode of the fuel cell, and A supply means for supplying a raw material to the anode of the fuel cell, switching to the bypass means side by the switching means, supplying water by the water supply means, and then supplying air by the purge air supply means. The fuel cell system may be a feature.

  According to a third aspect of the invention, there is provided the fuel cell system according to the first or second aspect, wherein the fuel cell stop operation is started before the voltage of the fuel cell reaches the open circuit voltage at the latest. Also good.

  According to a fourth aspect of the present invention, the raw material anode supply means starts supplying the raw material to the anode of the fuel cell after the raw material cathode supply means starts supplying the raw material to the cathode of the fuel cell. The fuel cell system according to the second aspect of the present invention may be used.

  Further, as a fifth aspect of the invention, there is provided anode closing means for closing an inlet and an outlet of the anode of the fuel cell, and the anode closing means is configured such that after the raw material anode supply means supplies the raw material to the anode of the fuel cell, The fuel cell system according to any one of the second to fourth aspects of the invention may be configured such that the inlet and the outlet of the anode of the fuel cell are closed.

  Further, as a sixth aspect of the invention, there is provided a cathode closing means for closing an inlet and an outlet of the cathode of the fuel cell, the cathode closing means after the raw material cathode supply means supplies the raw material to the cathode of the fuel cell, A fuel cell system according to any one of the first to fifth aspects of the present invention, wherein the inlet and the outlet of the cathode of the fuel cell are closed.

  Further, as a seventh aspect of the present invention, combustion for burning at least one of a raw material, residual fuel discharged from the anode of the fuel cell, and fuel supplied from the fuel generator via the bypass means The anode closing means opens the inlet and the outlet of the anode of the fuel cell after combustion is started in the combustor at the start-up of the apparatus. It is good also as a fuel cell system of either invention of 6.

(Embodiment 6)
Prior to the description of the fuel cell system of the present invention and the method for stopping the fuel cell system, the basic power generation principle of the solid polymer electrolyte fuel cell will be outlined again, and the purpose of preventing drying of the electrolyte membrane by the humidified raw material gas will be understood. Therefore, the necessity of water retention management of the electrolyte membrane will be explained.

In a fuel cell, a fuel gas such as hydrogen gas is supplied to an anode and an oxidant gas such as air is supplied to a cathode to cause them to react electrochemically to generate electricity and heat simultaneously.

  A polymer electrolyte membrane that selectively transports hydrogen ions is used as the electrolyte membrane, and the porous catalytic reaction layers disposed on both sides of the electrolyte membrane are mainly composed of carbon powder carrying a platinum-based metal catalyst. The reaction of the following formula (12) occurs in the catalytic reaction layer of the anode, the reaction of the following formula (13) occurs in the catalytic reaction layer of the cathode, and the fuel cell as a whole has the following formula (14). A reaction occurs.

(Chemical formula 12)
H ₂ → 2H + 2e ^-
(Chemical Formula 13)
1 / 2O ₂ + 2H ⁺ + 2e ⁻ → H ₂ O
(Chemical Formula 14)
H ₂ + 1 / 2O ₂ → H ₂ O
That is, hydrogen ions generated by the reaction of the formula (12) are transported from the anode to the cathode through the electrolyte membrane, and electrons are moved from the anode to the cathode through the external circuit. At the cathode, oxygen gas and hydrogen ions and Electrons react as shown in formula (13) to generate water, and heat of reaction due to catalytic reaction can be obtained.

  As described above, the electrolyte membrane needs to have a function of selectively transporting hydrogen ions. By holding water in the electrolyte membrane, ions that can transport hydrogen ions from the anode to the cathode using the water contained in the electrolyte membrane as a movement path. It is thought that conductivity develops.

  Therefore, in order to secure hydrogen ion transport capability, it is essential to retain the electrolyte membrane. Proper management of the electrolyte membrane water retention by preventing the electrolyte membrane from drying is important for the basic performance of the electrolyte membrane. Technical matter.

  Next, the configuration of an existing polymer electrolyte fuel cell will be described with reference to the drawings.

  FIG. 10 shows a cross-sectional view of a solid polymer electrolyte type fuel cell equipped with an electrolyte assembly (MEA).

  An anode 114a and a cathode 114c are arranged on both surfaces of a polymer electrolyte membrane 111 made of perfluorocarbon sulfonic acid having hydrogen ion conductivity so as to sandwich the electrolyte membrane 111. Note that the subscript a of the reference number indicates that related to the anode 114a on the side of the fuel gas such as hydrogen gas, and the subscript c indicates that related to the cathode 114c on the side of the oxidant gas such as air. ing.

  Both the anode 114a and the cathode 114c have a two-layer film structure, and the first layer film in contact with the electrolyte film 111 is a polymer having a hydrogen ion conductivity and a catalyst in which a noble metal such as platinum is supported on porous carbon. A catalyst reaction layer 112a (hereinafter referred to as catalyst reaction layer 112a) of the anode 114a and a catalyst reaction layer 112c (hereinafter referred to as catalyst reaction layer 112c) of the cathode 114c, which are made of a mixture with an electrolyte, and these catalyst reaction layers 112a and 112c. The second layer film laminated in close contact with the outer surface of the gas diffusion layer 113a of the anode 114a (hereinafter referred to as the gas diffusion layer 113a) and the gas diffusion layer 113c (hereinafter referred to as the gas diffusion layer 113c) of the cathode 114c having both air permeability and electrical conductivity. Gas diffusion layer 113c).

  The MEA 117 includes an electrolyte membrane 111, an anode 114a, and a cathode 114c. The MEA 117 is mechanically fixed, and adjacent MEAs 117 are electrically connected in series.

  Further, a conductive separator plate 116a (hereinafter referred to as a conductive separator plate 116a) for the anode 114a is disposed in contact with the outer surface of the anode 114a. , Referred to as a conductive separator plate 116c).

  Further, a fuel for the anode 114a comprising a groove (depth: 0.5 mm) for supplying a reaction gas to the anode 114a and the cathode 114c and carrying away a reaction product gas after the reaction and an excess reaction gas that did not contribute to the reaction. A gas flow path 18a (hereinafter referred to as gas flow path 18a) and an oxidant gas flow path 18c (hereinafter referred to as gas flow path 18c) for the cathode 114c are formed on the contact surfaces of the conductive separator plates 116a and 116c with the MEA 117. Yes.

  Thus, a fuel cell (single cell) 20 composed of the MEA 117 and the separator plates 116a and 116c is formed.

  For example, about 160 fuel cells 120 are stacked inside the fuel cell 121, and more specifically, the outer surface of the conductive separator plate 116a of one fuel cell 120 and the other fuel cell. The fuel cells 120 are stacked such that the outer surfaces of the conductive separator plates 116c of the cells 120 are adjacent to each other in contact with each other.

  Further, a groove (depth: 0.5 mm) 119a formed in the conductive separator plate 116a and a conductive separator plate 116c are formed on the contact surface of the conductive separator plate 116a and the conductive separator 116c adjacent thereto. A cooling water passage 19 including a groove (depth: 0.5 mm) 119c is provided.

  Thus, the temperature of the conductive separator plates 116a and 116c is adjusted by the cooling water flowing through the cooling water passage 119, and the temperature of the MEA 117 can be adjusted via these conductive separators 116a and 116c.

  As the conductive separator plates 116a and 116c, for example, graphite plates having an outer size of 20 cm × 32 cm × 1.3 mm and impregnated with a phenol resin are used.

  On the other hand, an MEA gasket 115a (hereinafter referred to as MEA gasket 115a) on the annular rubber anode 114a side and an MEA gasket 115c on the cathode 114c side on the anode side main surface and cathode side main surface of the outer peripheral portion of the MEA 117, respectively. (Hereinafter referred to as MEA gasket 115c) is provided, and the gap between the conductive separator plates 116a and 116c and the MEA 117 is sealed by the MEA gaskets 115a and 115c. Thus, gas mixing and gas leakage of the gas flowing through the gas flow paths 118a and 118c are prevented by the MEA gaskets 115a and 115c. Further, manifold holes (not shown) for cooling water flow, fuel gas flow, and oxidant gas flow are formed outside the MEA gaskets 115a and 115c.

  The configuration and operation of the gas supply system of the fuel cell power generator using the fuel cell as described above will be described with reference to the drawings. FIG. 11 is a block diagram showing a basic configuration of the fuel cell power generator.

  First, the basic configuration of the fuel cell power generator 1100 according to Embodiment 6 of the present invention will be described with reference to FIGS. 11 and 12.

  The fuel cell power generator 1100 mainly includes a raw material gas supply unit 122 for supplying a raw material gas to the fuel generator 123, a second water supply unit 175 for supplying water to the fuel generator 123, and a raw material gas supply unit 122. An oxidant gas (air) is supplied to the fuel generator 123 and the humidifier 123 that generate a hydrogen-rich fuel gas by a reforming reaction from the raw material gas supplied from the water and the water supplied from the second water supply means 175. A blower 128 serving as an air supply means, a first water supply means 174 for supplying water to the humidifier 124, the air supplied from the blower 128, the heat supplied from the fuel generator 123 and the first Humidifier 134 for humidifying with water supplied from water supply means 174, fuel gas supplied from fuel generator 123 to anode 114a, and humidifier The fuel cell 121, the raw material gas supply means 122, the first and second water supply means 174, 175, and the fuel generator 123 that generate electric power and generate heat using the humidified oxidant gas supplied from the cathode 24c to the cathode 114c. And a control unit 127 that controls appropriate control of the blower 128 and the fuel cell 121, a circuit unit 125 that extracts power generated by the fuel cell 121, a measurement unit 126 that measures the voltage (power generation voltage) of the circuit unit 125, and the like. It is configured.

  Further, the fuel cell power generation device 1100 is provided with a first switching valve 129 and first, second, and third shut-off valves 130, 131, and 132, which will be described in detail later, and are controlled by the control unit 127. In addition, the dotted line in FIG. 11 has shown the control signal.

  Next, the gas supply operation during normal operation (power generation) of the fuel cell power generator will be described.

  In the gas cleaning unit 122p of the source gas supply means 122, the performance deterioration material of the fuel cell contained in the source gas is removed to purify the source gas, and then the purified source gas is supplied to the fuel via the source gas supply pipe 163. It is supplied to the generator 123. In this case, since the city gas 13A containing methane gas, ethane gas, propane gas and butane gas is used as the raw material gas, the odorant tertiary butyl mercaptan (TBM) and dimethyl contained in the city gas 13A in the gas cleaning unit 22p. Impurities such as sulfide (DMS) and tetrahydrothiophine (THT) are adsorbed and removed.

  On the other hand, water is supplied into the fuel generator 23 from the second water supply means 175 (for example, a water supply pump).

  Thus, a hydrogen gas-rich fuel gas (reformed gas) is generated from the raw material gas and water vapor by the reforming reaction in the reforming section 123e of the fuel generator 123. The fuel gas delivered from the fuel generator 123 is communicated between the fuel gas supply pipe 161 and the anode side inlet 121a by the first switching valve 129, and then the anode side of the fuel cell 121 through the fuel gas supply pipe 161. It is supplied to the inlet 121a and used for the reaction of the formula (1) at the anode 114a. The first switching valve 129 is disposed in the middle of the fuel gas supply pipe 161 between the anode side inlet 121a and the fuel generator 123.

  Of the fuel gas supplied to the fuel cell 121, one that is not used for the power generation reaction in the fuel cell 121 is sent from the anode side outlet 121 b and is opened through the anode exhaust pipe 147 to be in the opened state. It is guided to the outside of the fuel cell 121 through 130.

  The first shut-off valve 130 is disposed in the middle of the anode exhaust pipe 147 between the anode side outlet 121b and the water removal unit 133. The remaining fuel gas led to the outside passes through the second check valve 148 (the direction in which the second check valve 148 allows the flow) in the middle of the anode exhaust pipe 147 and the first check valve. 141 prevents backflow in the direction of the first connecting pipe 164. Then, after the water is removed by the water removal unit 133 disposed in the anode exhaust pipe 147, the remaining fuel gas is sent to the combustion unit (not shown) of the fuel generator 123, and inside the combustion unit Burned. The heat generated by this combustion is used as heat for endothermic reaction such as reforming reaction.

  On the other hand, the oxidant gas (air) supplied from the blower 128 serving as the oxidant gas supply means to the humidifier 124 via the oxidant gas supply pipe 162 is humidified in the humidifier 124 and then opened. It is supplied to the cathode side inlet 121c of the fuel cell 121 through the oxidant gas supply pipe 162 through the second shutoff valve 131, and used for the reaction of the formula (2) at the cathode 114c. The second shut-off valve 131 is disposed in the middle of the oxidant gas supply pipe 162 between the humidifier 124 and the cathode side inlet 121c.

  Water necessary for humidification is supplied to the inside of the humidifier 124 from the first water supply means 174 (for example, a water supply pump), and the heat necessary for humidification is the fuel indicated by a double line in FIG. It is supplied from the generator 123 to the humidifier 124. Of the humidified oxidant gas supplied to the fuel cell 121, the one not used for the power generation reaction in the fuel cell 121 passes through the third shut-off valve 132 in the open state from the cathode-side outlet 121d to the outside of the fuel cell 121. The remaining oxidant gas is recirculated to the humidifier 124 again via the cathode exhaust pipe 160, and water and heat contained in the recirculated oxidant gas are sent from the blower 128 inside the humidifier 124. Give to the oxidant gas. The third shut-off valve 132 is disposed in the middle of the cathode exhaust pipe 160 between the cathode side outlet 121d and the humidifier 124. Further, as the humidifying unit 124, a total heat exchange humidifier 134 using an ion exchange membrane and a hot water humidifier 135 are used in combination.

  Here, the operation of the source gas supply means 122 and the blower 128, the first and second water supply means 174 and 175, the fuel generator 123 and the fuel cell 121, the switching operation of the first switching valve 129, and the first, The opening and closing operations of the second and third shut-off valves 130, 131, 132 are controlled by the control unit 127 based on detection signals (for example, temperature signals) of various devices, and appropriate DSS operation is performed.

  Thus, the circuit unit 125 is connected to the output terminal 172a (hereinafter referred to as the output terminal 172a) of the anode 114a and the output terminal 172c (hereinafter referred to as the output terminal 172c) of the cathode 114c, and is connected to the circuit unit 125 inside the fuel cell 121. The generated power is taken out, and the generated voltage of the circuit unit 125 is monitored by the measuring unit 126.

  Here, in the fuel generator 123, the monoxide contained in the fuel gas sent from the reforming unit 123e, in addition to the reforming unit 123e that reforms the raw material gas such as methane gas using water vapor. A CO shift section 123f that removes part of the carbon gas (CO gas) by a shift reaction and a CO removal section 123g that can reduce the CO gas concentration in the fuel gas sent from the CO shift section 123f to 10 ppm or less are provided. ing. By reducing the CO gas concentration below a predetermined concentration level, poisoning of platinum contained in the anode 114a by the CO gas in the operating temperature range of the fuel cell 121 can be prevented, and deterioration of its catalytic activity can be avoided. Of course, the anode 114a uses a catalyst having resistance to CO gas, such as platinum-ruthenium, and measures against poisoning of CO gas are taken in terms of the catalyst material.

  When the reaction transition in the fuel generator 123 is described more specifically by using methane gas as an example of the raw material gas, the following reaction is performed.

  In the reforming unit 123e, hydrogen gas (about 90%) and CO gas (about 10%) are generated by the steam reforming reaction shown in the equation (4).

CH ₄ + H ₂ O → CO + 3H ₂ (4)
Subsequently, the CO gas is oxidized into carbon dioxide at the CO shift section 123f, and the concentration thereof is reduced to about 5000 ppm (see the formula (5)). CO gas can also be removed by oxidation in the CO removal unit 123g on the downstream side of the shift unit 123f. However, since the CO removal unit 123g oxidizes not only CO gas but also useful hydrogen gas, it is possible in the CO shift unit 123f. It is desirable to reduce the CO gas concentration as much as possible.

CO + H ₂ O → CO ₂ + H ₂ (5)
Residual CO gas that could not be removed by the metamorphic portion 123f is oxidized and removed by the CO removing portion 123g, and the concentration thereof is reduced to about 10 ppm or less (see the equation (6)). In this way, it is possible to reach a CO gas concentration level that can be used as the fuel gas used in the fuel cell 121. Incidentally, the total reaction formula of the fuel generator 123 is shown in the formula (7).

CO + 1 / 2O ₂ → CO ₂ (6)
CH ₄ + 2H ₂ O → CO ₂ + 4H ₂ (7)
Next, the operation at the start of startup of the fuel cell power generation apparatus 100 will be described.

  If the temperature of the fuel generator 123 (reforming part 123e) is 640 ° C. or lower, the reforming reaction of the formula (4) is not generated in the fuel generator 123 (reforming part 123e). For this reason, at the start of startup, the gas delivered from the fuel gas is not led to the anode side inlet 121a, and the fuel gas supply pipe 161 is switched to the anode exhaust pipe 147 by the switching operation of the first switching valve 129. The connecting pipe 164 is communicated with the first check valve 141 provided in the middle thereof, and the gas sent from the fuel generator 123 is sent to the first check valve 141 (the first check valve is The direction of allowing flow) to the anode exhaust pipe 147. Thereafter, this gas is prevented from flowing back in the direction of the anode side outlet 121 b by the second check valve 148, and is removed by the water removal unit 133 and then supplied to the combustor of the fuel generator 123. It is burned inside the combustor. As a result, the temperature of the fuel generator 123 (the reforming unit 123e) can be quickly increased, and the time from the start to the power generation can be shortened.

  Furthermore, the operation | movement at the time of starting stop of the fuel cell power generation device 1100 is demonstrated.

  When starting and stopping the fuel cell power generation device 1100, the first switching valve 129 is operated to connect the fuel gas supply pipe 161 to the anode exhaust pipe 147, and the fuel gas supply pipe 161 and the anode side inlet 121a are shut off. Further, the first, second and third shut-off valves 130, 131 and 132 are closed, respectively. Thus, after starting and stopping, the fuel gas can be sealed in the anode 114a of the fuel cell 121, and the oxidant gas can be sealed in the cathode 14c of the fuel cell 121.

  As described above, the operation of the gas supply system of the basic configuration of the fuel cell power generator is outlined during normal operation (power generation), start-up, and operation stop. In a fuel cell power generation apparatus (for example, a household fuel cell power generation apparatus) that alternately repeats, the inside of the fuel cell is brought to a humidified source gas atmosphere during the transition period from the stop period of the fuel cell to the power generation period. The exposure eliminates the technical problem related to repeated operation of starting and stopping of the fuel cell, such as drying of the electrolyte membrane when the fuel cell is stopped and local combustion of the fuel cell due to oxygen gas mixing caused by long-term storage. be able to.

  Here, the humidification of the raw material gas refers to maintaining the atmosphere of the raw material gas so that the dew point of the raw material gas becomes equal to or higher than the operating temperature of the fuel cell.

  Hereinafter, a configuration example and an operation example of the gas supply system of the fuel cell power generation apparatus, in which the inside of the fuel cell is exposed to the humidified raw material gas during the transition period, will be described, and thereby the fuel cell of the present invention will be described. An embodiment of a system activation method will be described.

  FIG. 12 is a block diagram showing the configuration of the fuel cell power generator according to Embodiment 1, and FIGS. 13 and 14 are flowcharts for explaining the gas supply operation of the fuel cell power generator of FIG.

  Fuel cell 121, first water supply means 174, second water supply means 175, raw material gas supply means 122, fuel generator 123, humidifier 124, impedance measuring instrument 173, circuit part 125, measurement part 126 and control part The configuration of 127 is the same as that described in the basic configuration (see FIGS. 10 and 11).

  However, the fuel cell power generator described below has a basic configuration in that the input sensor of the control unit 127 such as a piping for introducing humidified raw material gas into the fuel cell 121, a switching valve, a shutoff valve, and a mass flow meter is as follows. Here, the description will focus on the changes in the input sensors such as the piping, the switching valve, the shutoff valve, and the mass flow meter.

  In FIG. 12, a mass flow meter 170a (hereinafter referred to as a mass flow meter 170a) of an anode 114a for measuring a gas flow rate is disposed in the middle of the fuel gas supply pipe 161 immediately after the outlet of the fuel generator 123. The first switching valve 129 downstream of the mass flow meter 170a and upstream of the anode inlet 121a of the fuel cell 121 extends from the fuel generator 123 and communicates with the anode inlet 121a. It is arranged in the middle.

  Further, the first switching valve 129 is communicated with the anode exhaust pipe 147 through the first connection pipe 164 in which the first check valve 141 is arranged as in FIG. In addition, the position of the connection site | part of the 1st connection piping 164 and the anode exhaust piping 147 exists between the water removal part 133 and the 2nd non-return valve 148. FIG.

  A second switching valve 142 is disposed in the middle of the anode exhaust pipe 147 extending from the anode outlet side 121b to the fuel generator 123, and is downstream of the second switching valve 142 and upstream of the water removal unit 133. The first shut-off valve 130 and the second check valve 148 are disposed in the order of the anode exhaust pipe 147 in this order.

  Further, in the middle of the oxidant gas supply pipe 162 extending from the humidifier 124 to the cathode side inlet 121c, a second shut-off valve 131 and a third switching valve 143 are provided in this order, and the humidifier from the cathode side outlet 121d is provided. A fourth switching valve 144 and a third shut-off valve 132 are provided in this order in the middle of the cathode exhaust pipe 160 extending to 121.

  In addition, the third switching valve 143 is connected to the middle of the anode exhaust pipe 147 through the first circulation pipe 145, and the fourth switching valve 144 is connected to the second switching valve 146 through the second circulation pipe 146. A switching valve 142 is connected. In addition, the position of the connection site | part of the 1st circulation piping 145 and the anode exhaust piping 147 exists between the water removal part 133 and the 2nd non-return valve 148. FIG.

  Further, a temperature detection means (preferably a thermocouple of a Pt resistor) 171 for detecting the temperature inside the fuel cell 121 is disposed in the vicinity of the center of the fuel cell 21 as shown in FIG. Embedded in the conductive separator plate 116c of the cathode 114c (see FIG. 10).

  Further, in order to obtain the membrane resistance (conductivity) of the electrolyte membrane 111 of the fuel cell 121 described in detail later, an impedance measuring device 173 connected to the output terminals 172a and 172c is provided.

  The circuit unit 125 is connected to the output terminals 172a and 172c, the electric power generated inside the fuel cell 121 in the circuit unit 125 is taken out, and the voltage (generated voltage) of the circuit unit 125 is monitored by the measuring unit 126. Is done.

  Here, the output signal of the mass flow meter 170a, the output signal of the temperature detection means 171 (via the measurement unit 126), and the output signals of the output terminals 172a and 172c (via the impedance measuring device 173) are input to the control unit 127. Is done. In this way, the flow rate of the raw material gas is monitored by the control unit 127 based on the output signal of the mass flow meter 170a, and the internal temperature of the fuel cell 121 is controlled by the control unit based on the processing signal processed by the measurement unit 126. 127, and the membrane resistance of the electrolyte membrane 111 is monitored by the control unit 127 based on the processed signal obtained by processing the output signals of the output terminals 172 a and 172 c by the impedance measuring device 173. In addition, the switching operation of the first, second, third, and fourth switching valves 129, 142, 143, and 144 described below by the control unit 127 and the first, second, and third shielding valves 130, 131, The opening / closing operation of 132 is controlled.

  Hereinafter, the fuel gas and oxidant gas supply operations are divided into the storage and stop operation and the start start operation of the fuel cell power generation device, the operation for confirming whether or not to start power generation, and the power generation operation. This will be described in detail with reference to FIG.

[Stopping storage operation of fuel cell power generator]
After the fuel cell power generation device 1100 is stopped, the fuel cell power generation device 1100 is stored for a long period of time by keeping the inside of the fuel cell 121 filled and sealed with the raw material gas. Here, in order to stop and store the fuel cell power generation device 1100, the switching valve and the shutoff valve are operated as follows (step S401).

  The first cutoff valve 130 connected to the second switching valve 142, the second cutoff valve 131 connected to the third switching valve 143, and the third cutoff valve 132 connected to the fourth switching valve 144 are closed. .

  In this state, the first switching valve 129 is operated to connect the fuel gas supply pipe 161 to the anode exhaust pipe 147, while the fuel gas supply pipe 161 is disconnected from the anode side inlet 121a. Further, the second switching valve 142 is operated to connect the anode side outlet 121b to the first shutoff valve 130, while the anode side outlet 121b is shut off from the second circulation pipe 146. Further, the third switching valve 143 is operated to connect the cathode side inlet 121c to the second shutoff valve 131, while the cathode side inlet 121c is shut off from the first circulation pipe 145. Furthermore, the fourth switching valve 144 is operated to connect the cathode side outlet 121d with the third shut-off valve 132, while the cathode side outlet 121d is shut off from the second circulation pipe 146.

  In this way, the fuel gas and the oxidant gas can be reliably sealed inside the fuel cell 21. Note that the inside of the fuel cell 21 is maintained at a fuel cell operating temperature (70 ° C.) or lower, and is usually kept near room temperature (about 20 ° C. to 30 ° C.).

[Starting operation of fuel cell generator]
In order to purge the inside of the fuel cell 121 with the humidified raw material gas, which will be described later, first, the raw material gas is selected and the raw material gas is cleaned so as not to adversely affect the catalyst of the fuel cell 121 (step S402).

  Specifically, for the purpose of preventing the hydrogen overvoltage from being increased by adsorbing the platinum catalyst of the fuel cell 121 on the surface, removal of impurities in the raw material gas, especially removal of sulfur components is indispensable cleaning treatment. It is. Further, as the selection of the raw material gas itself, it is necessary to select a gas that does not cause inhibition of the platinum catalyst activity of the fuel cell 121. From this viewpoint, methane gas, propane gas, butane gas, and ethane gas (or a mixed gas thereof) are selected. It is desirable to use any gas.

  Next, the temperature inside the fuel cell 121 is raised to the operating temperature (70 ° C.) (step S403).

  As a specific temperature raising method, for example, a heater (not shown) or hot water stored in a cogeneration water heater (not shown) of the fuel cell power generator 1100 is used. Note that the internal temperature of the fuel cell 121 is monitored by the control unit 27 based on the detection signal of the temperature detection means 171 to control an appropriate temperature raising operation of the fuel cell 121.

  Here, it is determined whether or not the internal temperature of the fuel cell 121 has reached the operating temperature (70 ° C.) or more (step S404). If the temperature rise is insufficient (No in S404), the temperature raising operation of S403 is performed. If the temperature reaches 70 ° C. or higher (Yes in S404), the process proceeds to the next step.

  Subsequently, in order to preheat the inside of the fuel generator 123, the switching valve and the shutoff valve are operated as follows (step S405).

  The first cutoff valve 130 connected to the second switching valve 142, the second cutoff valve 131 connected to the third switching valve 143, and the third cutoff valve 132 connected to the fourth switching valve 144 are closed. .

  In this state, the first switching valve 129 is operated to connect the fuel gas supply pipe 161 to the anode exhaust pipe 147, while the fuel gas supply pipe 161 is disconnected from the anode side inlet 121a. Further, the second switching valve 142 is operated to connect the anode side outlet 121b to the first shutoff valve 130, while the anode side outlet 121b is shut off from the second circulation pipe 146. Further, the third switching valve 143 is operated to connect the cathode side inlet 121c to the second shutoff valve 131, while the cathode side inlet 121c is shut off from the first circulation pipe 145. Furthermore, the fourth switching valve 144 is operated to connect the cathode side outlet 121d with the third shut-off valve 132, while the cathode side outlet 121d is shut off from the second circulation pipe 146.

  Thus, the gas sent from the fuel generator 123 and flowing through the fuel gas supply pipe 161 passes through the first connection pipe 164 (the direction in which the first check valve 141 allows the flow) and the anode exhaust pipe 147 and the fuel generator 123. It is made to recirculate | reflux to the combustion part of this, and it burns inside a combustion part.

  As a result, the fuel generator 123 is preheated to a predetermined temperature range (a temperature range in which CO gas is not generated from the raw material gas and water vapor in the fuel generator 123 (reforming section 123e) and carbon of the raw material gas is not precipitated). (Step S406).

  The specific temperature range of the fuel generator 123 is 300 ° C. or lower for the following reason. The range of the temperature rise temperature is preferably 250 ° C. or more from the viewpoint of heating and humidifying the raw material gas most efficiently.

  When the temperature of the fuel generator 23 exceeds 640 ° C., hydrogen gas is generated from the raw material gas and the water vapor by the reforming reaction of the fuel generator 123 (the reforming unit 123e). Is purged, there is a possibility that local combustion may occur inside the fuel cell 21 due to the hydrogen gas as soon as power generation is started.

  When the temperature of the fuel generator 123 (reforming part 123e) is 640 ° C. or lower, hydrogen gas is not generated by the reforming reaction, but within the temperature range of 500 ° C. or higher and 640 ° C. or lower, the fuel generator 123 (reforming part). In 123e), there is a possibility that the raw material gas is carbonized and carbon is deposited from the raw material gas, and it is not preferable to keep the temperature of the fuel generator 123 (reforming portion 123e) at 500 ° C. or higher. In addition, if the temperature of the fuel generator 123 (reformer 123e) is 300 ° C. or less, the carbon monoxide gas having the catalytic poisoning action of the MEA 117 in the fuel generator 123 (reformer 123e) is the raw material gas and water vapor. Will not occur.

  For the above reasons, it is preferable to keep the temperature of the fuel generator 123 (reformer 123e) at 300 ° C. or lower and use the raw material gas humidified in this temperature range as the purge processing gas.

  The temperature of the fuel generator 123 (reforming unit 123e) is monitored by the control unit 127 based on a detection signal of a reforming temperature measuring unit (not shown), and the fuel generator 123 (reforming unit 123e). The appropriate temperature rising operation is achieved.

  Here, it is determined whether or not the temperature of the fuel generator 123 (the reforming unit 123e) has been raised to a range of 250 ° C. to 300 ° C. (step S407), and if the temperature rise is insufficient (No in S407). When the preheating operation of the fuel generator 123 in S406 is continued and the temperature is raised to a range of 250 ° C. to 300 ° C. (Yes in S407), the process proceeds to the next step.

  After the preheating of the fuel generator 123, the raw material gas is maintained in the fuel generator 123 so that the dew point of the raw material gas supplied from the raw material gas supply means 122 can be maintained above the operating temperature (70 ° C.) of the fuel cell 121. The state is shifted to a state where the humidification process can be performed (step S408). The fuel generator 123 has already been heated to around 300 ° C., and water required for humidification can be supplied from the second water supply means 175 to the fuel generator 123. It is possible to humidify the source gas.

  Subsequently, the switching valve and the shutoff valve are operated as follows for supplying the humidified raw material gas (step S409).

  The first cutoff valve 130 connected to the second switching valve 142, the second cutoff valve 131 connected to the third switching valve 143, and the third cutoff valve 132 connected to the fourth switching valve 144 are closed. .

  In this state, the first switching valve 129 is operated to cut off the fuel gas supply pipe 161 from the anode exhaust pipe 147, while the fuel gas supply pipe 161 is communicated with the anode side inlet 121a. Further, the second switching valve 142 is operated to shut off the anode side outlet 121b from the first shut-off valve 130, while the anode side outlet 121b is connected to the second circulation pipe 146. Furthermore, the third switching valve 143 is operated to shut off the cathode side inlet 121c from the second shutoff valve 131, while the cathode side inlet 121c is communicated with the first circulation pipe 145. Furthermore, the fourth switching valve 144 is operated to shut off the cathode-side outlet 121d from the third shut-off valve 132, while allowing the cathode-side outlet 121d to communicate with the second circulation pipe 146.

  After performing the above valve operation, the humidified raw material gas sent from the fuel generator 123 humidifies the inside of the fuel cell 121 and is guided to the outside as follows. The purge process of replacing the atmosphere is performed (step S410).

  After the raw material gas supplied from the raw material gas supply means 122 is purified in the gas cleaning unit 122p, it is sent to the fuel generator 123 via the raw material gas supply pipe 163 and is humidified inside the fuel generator 123. . Thereafter, the humidified raw material gas is sent from the fuel generator 123 and flows into the fuel cell 121 from the anode side inlet 121a of the fuel cell 121 via the fuel gas supply pipe 161, so that the anode 114a has an atmosphere of the humidified raw material gas. Then, the humidified raw material gas is sent from the anode side outlet 121d and flows out of the fuel cell 121. Subsequently, the humidified source gas is switched in the direction of the second circulation pipe 146 by the second switching valve 142, passes through the second circulation pipe 146, and is fuel cell cathode side by the fourth switching valve 144. The direction is changed in the direction of the outlet 121d, and the fuel cell 121 flows again into the fuel cell 121 again. Thus, the cathode 114c is exposed to the atmosphere of the humidified raw material gas, and the raw material gas is sent out from the cathode side inlet 121c and flows out of the fuel cell 121 again.

  Thereafter, the direction of the raw material gas is switched by the third switching valve 143, flows in the direction of the first circulation pipe 145, and reaches the anode exhaust pipe 147. The raw material gas that has reached the anode exhaust pipe 147 is prevented from flowing back by the first and second check valves 141, 148, and is guided in the direction of the water removing unit 133, and is supplied from the humidified raw material gas in the water removing unit 133. After the water is removed, the fuel is sent to the combustion section of the fuel generator 123.

  That is, the humidified raw material gas passes through the periphery of the fuel cell 121 in the order of the anode side inlet 121a, the anode side outlet 121b, the cathode side outlet 121d, and the cathode side inlet 121c of the fuel cell 121 as shown by thick dotted lines in FIG. It flows in an annular shape and reaches the anode exhaust pipe 147. The fuel gas supplied to the combustion section is combusted inside the combustion section, and the heat generated by this combustion is used for heating the fuel generator 123.

  The total supply amount of the humidified raw material gas needs to be at least three times the gas filling capacity of the internal space of the fuel cell 121. For example, if the gas filling capacity is about 1.0 L, the flow rate 1 of the humidifying raw material gas is 1 This may be supplied to the inside of the fuel cell 121 for about 5 minutes at 5 L / min, and this total supply amount is monitored by the control unit 127 based on the output signal of the mass flow meter 170a.

  Thus, the inside of the fuel cell 121 can be exposed to the humidified raw material gas during the transition period from the stop period of the fuel cell 121 to the power generation period, and the electrolyte membrane 111 of the fuel cell 121 dried during the stop storage can be humidified. If oxygen gas is mixed into the fuel cell 121 during stopped storage, local combustion with the fuel gas caused by the oxygen gas can be prevented beforehand.

  Further, since the humidified raw material gas is introduced into the fuel cell 121 during the transition period from the stop period of the fuel cell 121 to the power generation period, the inside of the fuel cell 121 is exposed to the humidified raw material gas atmosphere for a long period of time. And the water repellency of the fuel cell electrode is not impaired.

  In addition, if oxygen gas mixed in the anode 114a during the storage stop of the fuel cell 121 remains, ruthenium elution occurs and the catalytic function is lost, so that the humidified raw material gas that is led to the cathode 114c after passing through the anode 114a The raw material gas supply method that preferentially excludes the oxygen gas of the anode 114a that is easily oxidized and deteriorated by adopting the introduction path makes sense from the viewpoint of preventing catalyst deterioration.

  Further, both the anode 114a and the cathode 114c can be humidified by a single humidified raw material gas supply path indicated by a thick dotted line in FIG. 12, and the gas supply piping can be simplified.

  After sufficiently supplying the humidified raw material gas into the fuel cell 121, the switching valve and the shutoff valve are operated as follows (step S411) to promote the heating of the fuel generator 123 of the fuel cell power generation device 1100. Then, the internal temperature of the fuel generator 123 (the reforming part 123e) is rapidly raised to a temperature (about 640 ° C. or higher) at which the reforming reaction of the formula (4) is possible.

  The first cutoff valve 130 connected to the second switching valve 142, the second cutoff valve 131 connected to the third switching valve 143, and the third cutoff valve 132 connected to the fourth switching valve 144 are closed. .

  In this state, the first switching valve 129 is operated to connect the fuel gas supply pipe 161 to the anode exhaust pipe 147, while the fuel gas supply pipe 161 is disconnected from the anode side inlet 121a. Further, the second switching valve 142 is operated to connect the anode side outlet 121b to the first shutoff valve 130, while the anode side outlet 121b is shut off from the second circulation pipe 146. Further, the third switching valve 143 is operated to connect the cathode side inlet 121c to the second shutoff valve 131, while the cathode side inlet 121c is shut off from the first circulation pipe 145. Furthermore, the fourth switching valve 144 is operated to connect the cathode side outlet 121d with the third shut-off valve 132, while the cathode side outlet 121d is shut off from the second circulation pipe 146.

  In this way, the gas sent from the fuel generator 123 to the fuel gas supply pipe 161 passes through the first connecting pipe 164 (the direction in which the first check valve 141 allows the flow) and the anode exhaust pipe 147 and the fuel generator 123. It is made to recirculate | reflux to the combustion part of this, and it burns inside a combustion part. Thereby, the fuel generator 123 is heated to a predetermined temperature range (temperature range in which hydrogen gas is generated from the raw material gas and water vapor by the reforming reaction; 640 ° C. or more) (step S412).

  Here, it is determined whether or not the temperature of the fuel generator 123 (the reforming unit 123e) has increased to 640 ° C. or more (step S413). If the temperature has not been increased sufficiently (No in S413), the heating in S412 is performed. When the operation is continued and the temperature reaches 640 ° C. or higher (Yes in S413), the process proceeds to the next step.

[Operation to confirm whether fuel cell generator can start power generation]
After the temperature inside the fuel generator 123 is raised to 640 ° C. or higher, the internal temperature of the fuel cell 121 and the conductivity of the electrolyte membrane 11 of the fuel cell 21 are checked, and the power generation of the fuel cell power generator 1100 is performed. Determine if it is okay to start.

  As a first confirmation operation, it is determined whether or not the internal temperature of the fuel cell 121 is equal to or higher than the operating temperature (70 ° C.) (step S414). If the temperature rise is insufficient (No in S414), the increase in S404 is performed. When the temperature operation is re-executed and the temperature is raised to 70 ° C. or higher (Yes in S414), the process proceeds to the next step.

As a second confirmation operation, the conductivity of the electrolyte membrane 111 of the fuel cell 121 is obtained to determine whether or not this conductivity: σ = 1.93 × 10 ⁻² Scm ⁻¹ or more (step S416). = 1.93 × 10 ⁻² Scm ⁻¹ (No in S416), it is determined that the electrolyte membrane 11 is insufficiently humidified, and the operations of S409 and S410 are re-executed (step S417), and σ = 1 .93 × 10 ⁻² Scm ⁻¹ or more (Yes in S416), the process proceeds to the next step.

  Here, the calculation method of the conductivity of the electrolyte membrane and the relationship between the conductivity of the electrolyte membrane and the relative humidity will be described with reference to the drawings.

In FIG. 15, the horizontal axis represents the actual resistance component Z ′, the vertical axis represents the reactance component Z ″, and the frequency of the alternating current applied to the fuel cell 121 (electrode area: 144 cm ² ) is 0.1 Hz to 1 kHz. An AC impedance profile diagram of the fuel cell 121 measured by varying the range is shown (impedance measurement by the AC method) According to Fig. 15, the AC impedance profile is represented by an abscissa (Z ') in an AC current having a frequency of 1 kHz. Therefore, it is presumed that the impedance at an alternating current with a frequency of 1 kHz indicates the resistance Rs of the electrolyte membrane 111. That is, Fig. 15 is a schematic diagram of a so-called Cole-Cole plot in which the alternating current impedance is measured. In this case, the one having a small resistance value at the intersection of the semicircle and the horizontal axis (see FIG. 15). Been Rs) means a membrane resistance of the electrolyte membrane 11.

  An AC voltage for measurement (1 kHz) is applied from the impedance measuring device 173 to the output terminals 172a and 172c of the fuel cell 121 connected to the impedance measuring device 173 (see FIG. 12) controlled by the control unit 127. The conductivity of the electrolyte membrane 111 can be estimated based on the alternating current impedance of the electrolyte membrane 111 of the fuel cell 121 obtained as a result. Specifically, for example, an alternating current voltage (1 kHz) is applied to each fuel cell 120 by measuring an alternating current impedance (110 kHz), and the conductivity of the electrolyte membrane 11 is determined from the measured value and the thickness and area of the electrolyte membrane 111. The rate is calculated.

If the conductivity obtained by such a calculation method is σ = 1.93 × 10 ⁻² Scm ⁻¹ or more, the fuel cell 121 is in a state in which power generation can be started for the following reason based on FIG. Can be determined.

  In FIG. 16, when the temperature of the electrolyte membrane 11 is kept at 80 ° C., the horizontal axis represents the relative humidity of the polymer electrolyte membrane (Nafion 112 electrolyte membrane of DuPont USA, film thickness is 50 μm), and the vertical axis represents The correlation between the electrolyte membranes is shown by taking the conductivity of the electrolyte membrane, and it is for explaining how the conductivity of the electrolyte membrane depends on the relative humidity of the electrolyte membrane.

According to FIG. 16, as the electrolyte membrane is dried, the conductivity of the electrolyte membrane gradually approaches zero (relative humidity: near 20%), but as the electrolyte membrane increases in humidity, the conductivity also increases monotonously. A trend is observed. Here, in view of the performance of the electrolyte membrane, assuming that the sufficiently maintained relative humidity is 50% or more, the conductivity corresponding to this relative humidity is σ = 1.93 × 10 ⁻² Scm ⁻¹ .

Therefore, the conductivity of the electrolyte membrane (for example, σ = 1.93 × 10 ⁻² Scm ^{−1 in the} case of the Nafion 112 electrolyte membrane) can be used as a simple index for obtaining the water retention state of the electrolyte membrane. In other words, it can be said that whether or not the fuel cell 121 can start power generation can be predicted based on the conductivity.

  In this way, in addition to the determination based on the temperature of the fuel cell, the generation start timing of the fuel cell having the stop period and the power generation period is determined based on the conductivity of the electrolyte membrane of the fuel cell, so that the water retention state of the electrolyte membrane is accurately determined. Thus, the reliability of the determination of the power generation start time of the fuel cell power generator can be improved.

[Power generation operation of fuel cell power generator]
After the numerical value of the confirmation operation reaches a predetermined value (specifically, the temperature of the fuel cell 121 is 70 ° C. or higher, the conductivity of the electrolyte membrane σ = 1.93 × 10 ⁻² Scm ⁻¹ or higher), the switching valve And the shut-off valve is operated as follows to generate power in the fuel cell 21 (steps S418 and S419).

  The first cutoff valve 130 connected to the second switching valve 142, the second cutoff valve 131 connected to the third switching valve 143, and the third cutoff valve 132 connected to the fourth switching valve 144 are all opened. Plug.

  In this state, the first switching valve 129 is operated to disconnect the fuel gas supply pipe 161 from the anode exhaust pipe 147, while the fuel gas supply pipe 161 is communicated with the anode side inlet 121a. Further, the second switching valve 142 is operated to connect the anode side outlet 121b to the first shutoff valve 130, while the anode side outlet 121b is shut off from the second circulation pipe 146. Then, the third switching valve 143 is operated to connect the cathode side inlet 121 c with the second shutoff valve 131, while the cathode side inlet 121 c is shut off from the first circulation pipe 145. Further, the fourth switching valve 144 is operated to connect the cathode side outlet 121d with the third shutoff valve 132, while the cathode side outlet 121d is shut off from the second circulation pipe 146.

  By operating the switching valve and the shutoff valve, the hydrogen gas-rich fuel gas sent from the fuel generator 123 via the fuel gas supply pipe 161 is introduced into the anode side inlet 121a of the fuel cell 121, and the anode side outlet 121b. The remaining fuel gas that has been discharged from the fuel and not consumed by the anode 114 a is recirculated to the fuel generator 123 of the fuel cell 121 via the anode exhaust pipe 147.

  On the other hand, humidified air (humidified oxidant gas) sent from the humidifier 123 through the oxidant gas supply pipe 162 is introduced into the cathode side inlet 121c of the fuel cell 121, and sent out from the cathode side outlet 121d to be supplied to the cathode 114c. The remaining oxidant gas that has not been consumed in the step is recirculated to the humidifier 124 of the fuel cell 121 via the cathode exhaust pipe 160.

  Thus, the fuel gas is supplied to the anode 114a, the oxidant gas is supplied to the cathode 114c, hydrogen ions and electrons are generated inside the fuel cell 121, and the current is supplied to the circuit unit 125 via the output terminals 172a and 172c. And the generated voltage is monitored in the measuring unit 126.

(Embodiment 7)
Hereinafter, while describing another configuration example of the gas supply system of the fuel cell power generation apparatus 1100 in which the inside of the fuel cell 121 is exposed to the humidified raw material gas during the transition period from the stop period to the power generation period, An embodiment of a fuel cell starting method of the present invention will be described.

  FIG. 17 is a block diagram showing the configuration of the fuel cell power generator according to Embodiment 7. In FIG.

  Fuel cell 121, first water supply means 174, second water supply means 175, raw material gas supply means 122, fuel generator 123, humidifier 124, impedance measuring instrument 173, circuit part 125, measurement part 126 and control part The configuration of 127 is the same as that described in the sixth embodiment.

  However, the seventh embodiment differs from the sixth embodiment (FIG. 12) in that the arrangement of the piping for introducing humidified raw material gas into the fuel cell 121, the switching valve, the shutoff valve, and the mass flow meter is changed as follows. Here, the description will focus on the changes in the piping, the switching valve, the shutoff valve, and the mass flow meter.

  The first circulation pipe 145 connecting the third switching valve 143 and the anode exhaust pipe 147 shown in FIG. 12 is removed. In addition, a sixth switching valve 154 is disposed immediately after the outlet of the gas cleaning unit 122p, whereby the purified raw material gas is sent to the humidifier 124 (the raw material gas branch pipe 151) and to the fuel generator 123. Perform the switching operation. In addition, a raw material gas branch pipe 151 that connects the third switching valve 143 and the sixth switching valve 154 through the inside of the humidifying unit 124 is provided. Further, a fifth switching valve 152 is added in the middle of the fuel gas supply pipe 161 connecting the downstream side of the first switching valve 129 and the upstream side of the anode side inlet 121a of the fuel cell 121. The second connecting pipe 153 that connects the switching valve 152 and the anode exhaust pipe 147 is provided. Note that the position of the connection portion between the second connection pipe 153 and the anode exhaust pipe 147 is between the second check valve 148 and the water removal unit 133. Further, the mass flow meter 170a (see FIG. 12) is removed, and the mass flow meter 170c (hereinafter referred to as the mass flow meter 170c) of the cathode 114c for measuring the gas flow rate is interposed between the humidifier 124 and the third switching valve 143. And disposed in the middle of the source gas branch pipe 151.

  Hereinafter, the supply operation of the fuel gas and the oxidant gas will be divided into a stop storage operation, a start start operation, a power generation start availability confirmation operation and a power generation operation, with reference to the block diagram of FIG. 17 and the flowcharts of FIGS. However, it explains in detail.

[Stopping storage operation of fuel cell power generator]
After the fuel cell power generator is stopped, the inside of the fuel cell 121 is kept in a state of being filled and sealed with the raw material gas and stored for a long time. Here, in order to stop and store the fuel cell power generator 1100, the switching valve and the shutoff valve are operated as follows (step S801).

  The first cutoff valve 130 connected to the second switching valve 142, the second cutoff valve 131 connected to the third switching valve 143, and the third cutoff valve 132 connected to the fourth switching valve 144 are closed. .

  In this state, the first switching valve 129 is operated to connect the fuel gas supply pipe 161 to the fifth switching valve 152, while the fuel gas supply pipe 161 is disconnected from the anode exhaust pipe 147. Further, the second switching valve 142 is operated to connect the anode side outlet 121b to the first shutoff valve 130, while the anode side outlet 121b is shut off from the second circulation pipe 146. Further, the third switching valve 143 is operated to connect the cathode side inlet 121c with the second shutoff valve 131, while the cathode side inlet 121c is shut off from the source gas branch pipe 151. Further, the fourth switching valve 144 is operated to connect the cathode side outlet 121d and the third shutoff valve 132, while the cathode side outlet 121d and the second circulation pipe 146 are shut off. In addition, the fifth switching valve 152 is operated to connect the anode side inlet 121a with the first switching valve 129, while the anode side inlet 121a is disconnected from the anode exhaust pipe 127.

  In this way, the fuel gas and the oxidant gas can be reliably sealed inside the fuel cell 121. The temperature inside the fuel cell 121 is usually near room temperature (about 20 ° C. to 30 ° C.), which is kept lower than the fuel cell operating temperature (70 ° C.).

[Starting operation of fuel cell generator]
First, the raw material gas is selected and the raw material gas is cleaned so as not to adversely affect the catalyst of the fuel cell 121 (step S802). The method of cleaning the source gas and the content of source gas selection are the same as in the sixth embodiment.

  Next, the temperature inside the fuel cell 121 is raised to the operating temperature (70 ° C.) (step S803). The temperature raising method inside the fuel cell 121 is the same as that described in the sixth embodiment.

  Here, it is determined whether or not the internal temperature of the fuel cell 121 has reached the operating temperature (70 ° C.) or more (step S804), and if the temperature rise is insufficient (No in S804), the temperature rise in S803. If the operation is continued and the temperature reaches 70 ° C. or higher (Yes in S804), the process proceeds to the next step.

  Subsequently, the raw material gas can be humidified inside the humidifier 124 using the water supplied from the first water supply means 174 to the humidifier 124 and the heat supplied from the fuel generator 123 to the humidifier 124. The state is shifted (step S805).

  Specifically, warm water is required to humidify the source gas, but the humidifier 124 does not have a combustor as a heat source, and accordingly, it is necessary to receive heat appropriately from the outside of the humidifier 124. In the seventh embodiment, the heat generated in the combustor of the fuel generator 123 is supplied to the humidifier 124 as shown in FIG. The temperature of the humidifier 124 is increased by giving.

  Subsequently, in order to supply the humidified raw material gas into the fuel cell 121, various shutoff valves and switching valves are operated as follows (step S806).

  The first cutoff valve 130 connected to the second switching valve 142, the second cutoff valve 131 connected to the third switching valve 143, and the third cutoff valve 132 connected to the fourth switching valve 144 are closed. .

  In this state, the second switching valve 142 is operated to shut off the anode-side outlet 121b from the first shut-off valve 130, while the anode-side outlet 121b and the second circulation pipe 146 are communicated. Further, the third switching valve 143 is operated to connect the cathode side inlet 121 c with the source gas branch pipe 151, while the cathode side inlet 21 c is shut off from the cutoff valve 131. Further, the fourth switching valve 144 is operated to shut off the cathode side outlet 121d from the second shutoff valve 131, while the cathode side outlet 121d is communicated with the second circulation pipe 146. In addition, the fifth switching valve 152 is operated to block the anode side inlet 121a from the first switching valve 129, while the anode side inlet 121a is connected to the anode exhaust pipe 147. Furthermore, the sixth switching valve 154 is operated to connect the gas cleaning unit 122p and the raw material gas branch pipe 151, while the gas cleaning unit 122p is disconnected from the fuel generator 123.

  In this way, the cleaning raw material gas is supplied into the fuel cell 121 through the following path (step S807), and a purge process is performed in which the inside of the fuel cell 121 is replaced with the humidified raw material gas atmosphere.

  The source gas supplied from the source gas supply means 122 and purified by the gas cleaning unit 122p is directed to the source gas branch pipe 151 by the sixth switching valve 154 through the source gas supply pipe 163 and supplied to the source gas. It flows into the humidifier 124 via the branch pipe 151 and is humidified inside the humidifier 124 (more precisely, a hot water humidifier).

  Subsequently, the humidified source gas is switched in the direction of the cathode side inlet 121 c of the fuel cell 121 by the third switching valve 143 and flows into the fuel cell 121. Thus, the cathode 114c is exposed to the atmosphere of the humidified source gas, and this humidified source gas flows out from the cathode side outlet 121d.

  The humidified source gas is then switched in the direction of the second circulation pipe 146 by the fourth switching valve 144, and the source gas passes through the second circulation pipe 146 along one side of the fuel cell 121, The switching valve 142 switches the direction in the direction of the anode-side outlet 121b of the fuel cell 121 and flows again into the fuel cell 121. Thus, the anode 114a is exposed to the atmosphere of the humidified raw material gas, and this humidified raw material gas flows out again from the anode side inlet 121a.

  The humidified raw material gas after the re-flow is switched in the direction of the second connection pipe 153 by the fifth switching valve 152 and reaches the anode exhaust pipe 147 through the second connection pipe 153. The raw material gas that has reached the anode exhaust pipe 147 is prevented from flowing back by the first and second check valves 141, 148, and is guided in the direction of the water removing unit 133, and is supplied from the humidified raw material gas in the water removing unit 133. After the water is removed, it is sent to the combustion section of the fuel generator 123 and burned inside the combustor.

  That is, the humidified raw material gas passes in the order of the cathode side inlet 121c and the cathode side outlet 121d, the anode side outlet 121b and the anode side inlet 121a of the fuel cell 121 as shown by the thick dotted line in FIG. It flows in a conical shape and reaches the anode exhaust pipe 471. The total supply amount of the humidified raw material gas needs to be at least three times the gas filling capacity of the internal space of the fuel cell 121. For example, if the gas filling capacity is about 1.0 L, the flow rate 1 of the humidifying raw material gas is 1 This may be supplied to the inside of the fuel cell 121 at about 5 L / min for about 5 minutes, and this total supply amount is monitored by the control unit 127 based on the output signal of the mass flow meter 70c.

  In this way, the inside of the fuel cell 121 can be exposed to the humidified raw material gas during the transition period from the stop period of the fuel cell 121 to the power generation period, and the electrolyte membrane 111 of the fuel cell 21 dried during stop storage can be humidified. If oxygen gas is mixed into the fuel cell 121 during stopped storage, local combustion with the fuel gas caused by the oxygen gas can be prevented.

  Further, since the humidified raw material gas is introduced into the fuel cell 121 during the transition period from the stop period of the fuel cell 121 to the power generation period, the inside of the fuel cell 121 is exposed to the humidified raw material gas atmosphere for a long period of time. And the water repellency of the electrode of the fuel cell 121 is not impaired.

  In addition, as shown by the thick dotted line in FIG. 17, both the one anode 14a and the cathode 114c can be humidified by a single path, and the gas supply piping can be simplified.

  After sufficiently supplying the humidified raw material gas into the fuel cell 121, the switching valve and the shutoff valve are operated as follows for heating the fuel generator 123 (step S808).

  The first cutoff valve 130 connected to the second switching valve 142, the second cutoff valve 131 connected to the third switching valve 143, and the third cutoff valve 132 connected to the fourth switching valve 144 are closed. .

  In this state, the first switching valve 129 is operated to connect the fuel gas supply pipe 161 to the anode exhaust pipe 147, while the fuel gas supply pipe 161 is shut off from the fifth switching valve 152. Further, the second switching valve 142 is operated to connect the anode side outlet 121b to the first shutoff valve 130, while the anode side outlet 121b is shut off from the second circulation pipe 146. Further, the third switching valve 143 is operated to connect the cathode side inlet 121c with the second shutoff valve 131, while the cathode side inlet 121c is shut off from the source gas branch pipe 151. In addition, the fourth switching valve 144 is operated to connect the cathode side outlet 121d with the third shutoff valve 132, while the cathode side outlet 121d is shut off from the second circulation pipe 146. Further, the fifth switching valve 152 is operated to connect the anode side inlet 121a with the first switching valve 129, while the anode side inlet 121a is shut off from the anode exhaust pipe 147.

  Further, the sixth switching valve 154 is operated to connect the gas cleaning unit 122p with the fuel generator 123, while the gas cleaning unit 122p is disconnected from the source gas branch pipe 151.

  After performing the above valve operation, the gas sent from the fuel generator 123 is switched by the first switching valve 129 and passes through the first connection pipe 164 and the anode exhaust pipe 147 (first reverse). The stop valve 141 permits flow), and after the water is removed by the water removal unit 133, the fuel generator 123 can be refluxed and combusted in the combustion unit of the fuel generator 123. If possible (step S809), the internal temperature of the fuel generator 123 (the reforming unit 123e) can be raised to a temperature (about 640 ° C. or higher) at which the reforming reaction of the equation (4) is possible.

  Here, it is determined whether or not the temperature of the fuel generator 123 has been raised to 640 ° C. or more (step S810). If the temperature has not been raised sufficiently (No in S810), the heating operation in S809 is continued, and 640 is obtained. When the temperature reaches or exceeds ° C. (Yes in S810), the process proceeds to the next step.

[Operation to confirm whether fuel cell generator can start power generation]
After raising the temperature of the fuel generator 123 to 640 ° C. or more, the internal temperature of the fuel cell 121 and the conductivity of the electrolyte membrane 111 of the fuel cell 121 are confirmed, and the power generation of the fuel cell power generator 1100 is started. Determine whether or not

  As a first confirmation operation, it is determined whether or not the internal temperature of the fuel cell 121 is equal to or higher than the operating temperature (70 ° C.) (step S811). If the temperature rise is insufficient (No in S811), the increase in S803 is performed. When the temperature operation is re-executed (step S812) and the temperature is raised to 70 ° C. or higher (Yes in S811), the process proceeds to the next step.

As a second confirmation operation, the conductivity of the electrolyte membrane 111 of the fuel cell 121 is obtained to determine whether or not this conductivity: σ = 1.93 × 10 ⁻² Scm ⁻¹ (step S813). = 1.93 × 10 ⁻² Scm ⁻¹ (No in S813), it is determined that the electrolyte membrane 111 is insufficiently humidified, and the operations of S806 and S807 are re-executed (step S814), and σ = 1 .93 × 10 ⁻² Scm ⁻¹ or more (Yes in S813), the process proceeds to the next step. The method for measuring the conductivity of the electrolyte membrane and the relationship between the conductivity of the electrolyte membrane and the relative humidity are the same as those described in the sixth embodiment.

  In this way, in addition to the determination based on the temperature of the fuel cell, the generation start timing of the fuel cell having the stop period and the power generation period is determined based on the conductivity of the electrolyte membrane of the fuel cell, so the water retention state of the electrolyte membrane is accurately Thus, the reliability of the determination of the power generation start time of the fuel cell power generator can be improved.

[Power generation operation of fuel cell power generator]
After the numerical value of the confirmation operation reaches a predetermined value (specifically, the temperature of the fuel cell 121 is 70 ° C. or higher, the conductivity of the electrolyte membrane σ = 1.93 × 10 ⁻² Scm ⁻¹ or higher), the switching valve Then, the fuel cell 121 is caused to generate electric power by operating the shut-off valve as follows (steps S815 and S816).

  The first cutoff valve 130 connected to the second switching valve 142, the second cutoff valve 131 connected to the third switching valve 143, and the third cutoff valve 132 connected to the fourth switching valve 144 are all opened. Plug.

  In this state, the first switching valve 129 is operated to disconnect the fuel gas supply pipe 161 from the anode exhaust pipe 147, while the fuel gas supply pipe 161 is communicated with the fifth switching valve 152. Further, the second switching valve 142 is operated to connect the anode side outlet 121b to the first shutoff valve 130, while the anode side outlet 121b is shut off from the second circulation pipe 146. Further, the third switching valve 143 is operated to cause the cathode side inlet 121c to communicate with the second shutoff valve 131, while the cathode side inlet 121c is shut off from the source gas branch pipe 151. Further, the fourth switching valve 144 is operated to connect the cathode side outlet 121d with the third shutoff valve 132, while the cathode side outlet 121d is shut off from the second circulation pipe 146. In addition, the fifth switching valve 152 is operated to connect the anode side inlet 121a with the first switching valve 129, while the anode side inlet 121a is disconnected from the anode exhaust pipe 147. Further, the sixth switching valve 154 is operated to connect the gas cleaning unit 122p with the fuel generator 123, while the gas cleaning unit 122p is disconnected from the source gas branch pipe 151.

  In this way, the operation of the switching valve and the shutoff valve introduces the hydrogen gas-rich fuel gas from the fuel generator 123 to the anode side inlet 121a of the fuel cell 121 via the fuel gas supply pipe 161 and sends it out from the anode side outlet 121b. The remaining fuel gas that has not been consumed in 114 a is recirculated to the fuel generator 123 of the fuel cell 121 via the anode exhaust pipe 147.

  On the other hand, the humidified air (oxidant gas) sent from the humidifier 123 via the oxidant gas supply pipe 162 is introduced into the cathode side inlet 121c of the fuel cell 121, and sent out from the cathode side outlet 121d, and is sent from the cathode 114c. The remaining oxidant gas that has not been consumed is recirculated to the humidifier 124 of the fuel cell 121 via the cathode exhaust pipe 160.

  As a result, fuel gas is supplied to the anode 114a, oxidant gas is supplied to the cathode 114c, hydrogen ions and electrons are generated inside the fuel cell 121, and are supplied to the circuit unit 125 via the output terminals 172a and 72c. The current can be taken out, and the generated voltage is monitored in the measuring unit 126.

(Embodiment 8)
Hereinafter, another configuration example of the gas supply system of the fuel cell power generation apparatus, in which the inside of the fuel cell 121 is exposed to the humidified raw material gas during the transition period from the stop period to the power generation period, will be described.

  FIG. 20 is a block diagram showing the configuration of the fuel cell power generator according to Embodiment 3. Fuel cell 121, first water supply means 174, second water supply means 175, raw material gas supply means 122, fuel generator 123, humidifier 124, impedance measuring instrument 173, circuit part 125, measurement part 126 and control part The configuration of 127 is the same as that described in the sixth embodiment.

  The eighth embodiment is different from the sixth embodiment in that the arrangement of the piping for introducing the humidified raw material gas into the fuel cell 121, the switching valve, the shutoff valve, and the mass flow meter is changed. Here, the sixth embodiment is different from the sixth embodiment. On the other hand, the description will focus on the changes in the introduction piping, the switching valve, the shutoff valve, and the mass flow meter.

  The second and fourth switching valves 142 and 144 and the first and second circulation pipes 145 and 146 used in the sixth embodiment (FIG. 12) are removed. In addition, a diverter valve 155 is disposed immediately after the outlet of the gas cleaning unit 122p, and the diverter valve 155 determines the ratio of the flow rate of the raw material gas flowing in the direction of the humidifier 123 and the flow rate of the raw material gas flowing in the direction of the fuel generator 123. be able to. In addition, a raw material gas branch pipe 151 that connects the third switching valve 143 and the diversion valve 155 through the inside of the humidifying unit 124 is provided. Further, in addition to the mass flow meter 170 a, a mass flow meter 170 c is provided between the humidifier 124 and the third switching valve 143 and in the middle of the raw material gas branch pipe 151.

  Hereinafter, the supply operation of the fuel gas and the oxidant gas is divided into the stop storage operation, the start start operation, the power generation start availability confirmation operation and the power generation operation, with reference to the block diagram of FIG. 20 and the flowcharts of FIGS. I will explain in detail.

[Stopping storage operation of fuel cell power generator]
After the fuel cell power generation device 1100 is stopped, the inside of the fuel cell 121 is kept in a state of being filled and sealed with the raw material gas and stored for a long time. Here, in order to stop and store the fuel cell power generator 1100, the switching valve and the shutoff valve are operated as follows (step S1001).

  The first cutoff valve 130 connected to the anode side outlet 121b, the second cutoff valve 131 connected to the third switching valve 143, and the third cutoff valve 132 connected to the cathode side outlet 121d are closed.

  In this state, the first switching valve 129 is operated to connect the fuel gas supply pipe 161 to the anode exhaust pipe 147, while the fuel gas supply pipe 161 is disconnected from the anode side inlet 121a. Further, the third switching valve 143 is operated to cause the cathode side inlet 121c to communicate with the second shutoff valve 131, while the cathode side inlet 121c is shut off from the source gas branch pipe 151.

  In this way, the fuel gas and the oxidant gas can be reliably sealed inside the fuel cell 121. Note that the inside of the fuel cell 121 is maintained at a fuel cell operating temperature (70 ° C.) or lower, and is kept near room temperature (about 20 ° C. to 30 ° C.).

[Starting operation of fuel cell generator]
A raw material gas is selected and a raw material gas is cleaned so as not to adversely affect the catalyst of the fuel cell 121 (step S1002). The method of cleaning the source gas and the content of source gas selection are the same as in the sixth embodiment.

  Subsequently, the temperature inside the fuel cell 121 is raised to the operating temperature (70 ° C.) (step S1003). The temperature raising method inside the fuel cell 121 is the same as that described in the sixth embodiment.

  Here, it is determined whether or not the internal temperature of the fuel cell 121 has reached the operating temperature (70 ° C.) or more (step S1004). If the temperature rise is insufficient (No in S1004), the temperature rise in S1003. If the operation is continued and the temperature reaches 70 ° C. or higher (Yes in S1004), the process proceeds to the next step.

  Next, in order to preheat the inside of the fuel generator 123, the switching valve and the shutoff valve are operated as follows (step S1005).

  The first cutoff valve 130 connected to the anode side outlet 121b, the second cutoff valve 131 connected to the third switching valve 143, and the third cutoff valve 132 connected to the cathode side outlet 121d are closed.

  In this state, the first switching valve 129 is operated to connect the fuel gas supply pipe 161 to the anode exhaust pipe 147, while the fuel gas supply pipe 161 is disconnected from the anode side inlet 121a. Further, the third switching valve 143 is operated to cause the cathode side inlet 121c to communicate with the second shutoff valve 131, while the cathode side inlet 121c is shut off from the source gas branch pipe 151. Further, the raw material gas flowing through the fuel gas supply pipe 161 with respect to the flow rate of the raw material gas flowing through the raw material gas supply pipe 163 so as to guide the entire amount of the raw material gas flowing through the raw material gas supply pipe 163 to the fuel generator 123 by operating the diversion valve 155. Set the flow diversion ratio to 1.

  Thus, the gas sent from the fuel generator 123 passes through the first connecting pipe 164 by the switching operation of the first switching valve 129 (the direction in which the first check valve 141 allows the flow), and the anode exhaust pipe 147. Then, the backflow is prevented by the second check valve 148 and is returned to the combustion part of the fuel generator 23 and burned in the combustion part to preheat the fuel generator 123 (step S1006).

  The temperature increase range of the preheating of the fuel generator 123 is the same as that described in the sixth embodiment (the temperature of the fuel generator 123 (reforming portion 123e) is increased to a range of 250 ° C. to 300 ° C.) It is.

  Here, it is determined whether or not the temperature of the fuel generator 123 (the reforming unit 123e) has been raised to a range of 250 ° C. to 300 ° C. (step S1007), and if the temperature rise is insufficient (No in S1007). When the preheating operation of the fuel generator 123 in S1006 is continued and the temperature is raised to a range of 250 ° C. to 300 ° C. (Yes in S1007), the process proceeds to the next step.

  After the fuel generator 123 is preheated, the source gas is supplied so that the dew point of the source gas supplied from the source gas supply means 122 in the fuel generator 123 and the humidifier 124 can be maintained at or above the operating temperature (70 ° C.) of the fuel cell 121. Is moved to a state where the humidification process can be performed (step S1008). The fuel generator 123 has been heated to around 300 ° C., and water necessary for humidification is supplied from the second water supply means 175 to the fuel generator 123, whereby the source gas is humidified inside the fuel generator 123. it can. At the same time, the source gas can be humidified inside the humidifier 124 by the water supplied from the first water supply means 174 to the inside of the humidifier 124 and the heat supplied from the fuel generator 123 to the humidifier 124.

Subsequently, the switching valve and the shutoff valve are operated as follows for supplying the humidified raw material gas (step S1009).

  The first cutoff valve 130 connected to the second switching valve 142 and the third cutoff valve 132 connected to the fourth switching valve 144 are opened.

  In this state, the first switching valve 129 is operated to connect the anode side inlet 121a with the fuel gas supply pipe 161, while the anode side inlet 121a is shut off from the anode exhaust pipe 147. Further, the third switching valve 143 is operated to connect the cathode side inlet 121 c to the source gas branch pipe 151, while the cathode side inlet 121 c is shut off from the cutoff valve 131. Further, the flow dividing valve 155 is operated, and the flow dividing ratio is set to 0.5 so that the purified raw material gas delivered from the gas cleaning unit 122p can be led almost uniformly to both the humidifier 123 and the fuel generator 123. .

  Thus, the humidified raw material gas sent from the gas cleaning unit 122p humidifies the inside of the fuel cell 121 and is guided to the outside as follows, and purges the inside of the fuel cell 121 with the humidified raw material gas atmosphere. Processing is performed (step S1010).

  The source gas purified by the gas cleaning unit 122p and sent through the source gas supply pipe 163 is almost the same as the first source gas flowing through the source gas branch pipe 151 and the second source gas flowing through the fuel gas supply pipe 161. The flow is divided evenly (diversion ratio: 0.5).

  In the first source gas, the purified source gas sent from the gas cleaning unit 122p through the source gas supply pipe 163 is divided by the diversion valve 155 and led to the humidifier 124 through the source gas branch pipe 151. And humidified in the humidifier 124. Thereafter, the humidified source gas is switched to the cathode side inlet 121c of the fuel cell 121 by the third switching valve 143 and is supplied to the cathode 114c via the source gas branch pipe 151. Thus, after the cathode 114c of the fuel cell 121 is exposed to the atmosphere of the humidified raw material gas, the humidified raw material gas flows out from the cathode side outlet 121d. The humidified raw material gas after flowing out returns to the humidifying section 124 through the cathode exhaust pipe 160, is processed in the humidifying section 124, and is appropriately diluted and discharged to the atmosphere.

  In the second raw material gas, the purified raw material gas sent from the gas cleaning unit 122p through the raw material gas supply pipe 163 is diverted by the diversion valve 155 and led to the fuel generator 123. Humidified inside. Thereafter, the humidified raw material gas sent from the fuel generator 123 is switched to the anode side inlet 121a of the fuel cell by the first switching valve 129 and supplied to the anode 114a of the fuel cell 121 via the fuel gas supply pipe 161. Is done. Thus, after the anode 114a is exposed to the atmosphere of the humidified raw material gas, the humidified raw material gas flows out of the fuel cell 121 from the anode outlet 121b. After the outflow, the humidified raw material gas is removed by the water removal unit 133 through the anode exhaust pipe 147 and then returned to the combustion unit of the fuel generator 123 and burned in the combustion unit to heat the fuel generator 123. Used.

  Here, the total supply amount of the humidified raw material gas needs to be at least three times the gas fillable volume of the internal space of the fuel cell 121. For example, if the gas fillable volume is about 1.0 L, the humidified raw material gas The flow rate of 1.5 L / min for about 5 minutes may be supplied to the inside of the fuel cell 121. The total supply amount is monitored by the control unit 127 based on the output signals of the mass flow meter 170a and the mass flow meter 170c. The

  Thus, the inside of the fuel cell 121 can be exposed to the humidified raw material gas during the transition period from the stop period of the fuel cell 121 to the power generation period, and the electrolyte membrane 111 of the fuel cell 121 dried during the stop storage can be humidified. If oxygen gas is mixed inside the fuel cell during stopped storage, local combustion with the fuel gas caused by the oxygen gas can be prevented beforehand. Further, since the humidified raw material gas is introduced into the fuel cell 121 during the transition period from the stop period of the fuel cell 121 to the power generation period, the inside of the fuel cell 121 is exposed to the humidified raw material gas atmosphere for a long period of time. And the water repellency of the fuel cell electrode is not impaired. In addition, the first source gas and the second source gas are separately mixed without being mixed with each other, and the first source gas is passed through the cathode 114c of the fuel cell 121, and the second source gas is passed through the anode 114a of the fuel cell 121. Therefore, it is possible to reliably humidify both the anode 114a and the cathode 114c.

  After sufficiently supplying the humidified raw material gas into the fuel cell 121, the switching valve and the shut-off valve are operated as follows in order to heat the fuel generator 123 (step S1011).

  The first cutoff valve 130 connected to the anode side outlet 121b, the second cutoff valve 131 connected to the third switching valve 143, and the third cutoff valve 132 connected to the cathode side outlet 121d are closed.

  In this state, the first switching valve 129 is operated to connect the fuel gas supply pipe 161 to the anode exhaust pipe 147, while the fuel gas supply pipe 161 is disconnected from the anode side inlet 121a. Further, the third switching valve 143 is operated to cause the cathode side inlet 121c to communicate with the second shutoff valve 131, while the cathode side inlet 121c is shut off from the source gas branch pipe 151. The flow rate of the raw material gas flowing through the fuel gas supply pipe 161 with respect to the flow rate of the raw material gas flowing through the raw material gas supply pipe 163 is controlled so as to guide the entire amount of the raw material gas flowing through the raw material gas supply pipe 163 to the fuel generator 123 by operating the shunt valve 155. Set the diversion ratio to 1.

  Thus, the gas sent from the fuel generator 123 passes through the first connecting pipe 164 by the switching operation of the first switching valve 129 (the direction in which the first check valve 141 allows the flow), and the anode exhaust pipe 147. Then, the second check valve 148 prevents the back flow in the direction of the anode side outlet 121b, and recirculates to the combustion part of the fuel generator 123 and burns it in the combustion part to heat the fuel generator 123 ( Step S1012).

  Here, it is determined whether or not the temperature of the fuel generator 123 has been raised to 640 ° C. or more (step S1013). If the temperature has not been raised sufficiently (No in S1013), the heating operation in S1012 is continued, and 640 is obtained. If the temperature reaches or exceeds ° C. (Yes in S1013), the process proceeds to the next step.

[Operation to confirm whether fuel cell generator can start power generation]
After the completion of the temperature increase of the fuel generator 123, whether or not the internal temperature of the fuel cell 121 and the conductivity of the electrolyte membrane 111 of the fuel cell 121 are confirmed to start the power generation of the fuel cell power generator 1100. Determine whether.

  As a first confirmation operation, it is determined whether or not the internal temperature of the fuel cell 121 is equal to or higher than the operating temperature (70 ° C.) (step S1014). If the temperature rise is insufficient (No in S1014), the process proceeds to step S1003. When the temperature raising operation is performed again (step S1015) and the temperature is raised to 70 ° C. or higher (Yes in S1014), the process proceeds to the next step.

As a second confirmation operation, the conductivity of the electrolyte membrane 111 of the fuel cell 121 is measured to determine whether or not this conductivity: σ = 1.93 × 10 ⁻² Scm ⁻¹ or more (step S1016). If σ = 1.93 × 10 ⁻² Scm ⁻¹ (No in S1016), it is determined that the electrolyte membrane 111 is insufficiently humidified, and the operations of S1009 and S1010 are re-executed (step S1017). If 1.93 × 10 ⁻² Scm ⁻¹ or more (Yes in S1017), the process proceeds to the next step.

  The method for measuring the conductivity of the electrolyte membrane and the relationship between the conductivity of the electrolyte membrane and the relative humidity are the same as those described in the sixth embodiment.

  In this way, in addition to the determination based on the temperature of the fuel cell, the generation start timing of the fuel cell having the stop period and the power generation period is determined based on the conductivity of the electrolyte membrane of the fuel cell, so that the water retention state of the electrolyte membrane is accurately determined. Thus, the reliability of the determination of the power generation start time of the fuel cell power generator can be improved.

[Power generation operation of fuel cell power generator]
After the above confirmation operation reaches a predetermined value (specifically, the internal temperature of the fuel cell 121 is 70 ° C. or higher and the electrolyte membrane conductivity σ = 1.93 × 10 ⁻² Scm ⁻¹ or higher), the switching valve and The shut-off valve is operated as follows to generate power in the fuel cell 21 (steps S1018 and S1019).

  All of the first cutoff valve 130 connected to the anode side outlet 121b, the second cutoff valve 131 connected to the third switching valve 143, and the third cutoff valve 132 connected to the cathode side outlet 121d are opened.

  In this state, the first switching valve 129 is operated to cut off the fuel gas supply pipe 161 from the anode exhaust pipe 147, while the fuel gas supply pipe 161 is communicated with the anode side inlet 121a. Further, the third switching valve 143 is operated to cause the cathode side inlet 121c to communicate with the second shutoff valve 131, while the cathode side inlet 121c is shut off from the source gas branch pipe 151. In addition, the raw material flowing through the fuel gas supply pipe 161 with respect to the flow rate of the raw material gas flowing through the raw material gas supply pipe 163 is such that all the raw material gas flowing through the raw material gas supply pipe 163 is guided to the fuel generator 123 by operating the diversion valve 155. Set the gas flow diversion ratio to 1.

  By the operation of the switching valve and the shutoff valve, the hydrogen gas-rich fuel gas sent from the fuel generator 123 via the fuel gas supply pipe 161 is introduced into the anode side inlet 121a of the fuel cell 121 and sent out from the anode side outlet 121b. Then, the remaining fuel gas that has not been consumed by the anode 114 a is recirculated to the fuel generator 123 of the fuel cell 121 via the anode exhaust pipe 147. Further, humidified air (oxidant gas) is introduced from the humidifier 123 into the cathode side inlet 121c of the fuel cell 121 via the oxidant gas supply pipe 162, and is sent from the cathode side outlet 121d and is not consumed at the cathode 114c. The remaining oxidant gas is recirculated to the humidifier 124 of the fuel cell 121 via the cathode exhaust pipe 160.

  As a result, fuel gas is supplied to the anode 114a, oxidant gas is supplied to the cathode 114c, hydrogen ions and electrons are generated inside the fuel cell 121, and are supplied to the circuit unit 125 via the output terminals 172a and 72c. The current can be taken out, and the generated voltage is monitored in the measuring unit 126.

(Example)
The effect of fuel cell performance stabilization brought about by the humidified raw material gas purging process described in the sixth to eighth embodiments was verified by the following characteristic evaluation of the fuel cell 121 (voltage evaluation of the MEA 17). In the characteristic evaluation of the fuel cell 121, the following materials are used as the catalyst material of the fuel cell power generator 1100.

Zeolite is used as an example of the material of the desulfurization catalyst body, Ru / Al ₂ O ₃ is used as an example of the reforming catalyst body of the reforming portion 23e, and Pt / CeZrOx (Pt = 2 wt) as an example of the transformation catalyst body of the transformation portion 23f. %, Ce: Zr = 1: 1, x = 3 or 4), and as an example of a CO removal catalyst body of the CO removal portion 23g, Pt / Al ₂ O ₃ and Ru / zeolite are used as a honeycomb and Pt / Al ₂ O ₃ (upstream) and Ru / zeolite are used 1: 1.

  Further, the MEA 117 of the fuel cell 121 is manufactured by the following manufacturing method.

  66 parts by weight of a catalyst body (50% by weight of Pt) obtained by supporting a Pt catalyst on Ketjen Black (Ketjen Black EC manufactured by Ketjen Black International Co., Ltd., particle size 30 nm), which is carbon powder, Catalytic reaction by molding a mixture obtained by mixing 33 parts by weight (polymer dry weight) of perfluorocarbon sulfonate ionomer (5% by weight Nafion dispersion manufactured by Aldrich, USA) as a conductive material and binder Layers 12a and 12c (10 to 20 μm) are formed.

  Carbon powder acetylene black (Denka Black manufactured by Denki Kagaku Kogyo Co., Ltd., particle size 35 nm) is mixed with an aqueous dispersion of polytetrafluoroethylene (PTFE) (D1 manufactured by Daikin Kogyo Co., Ltd.) as a dry weight A water repellent ink containing 20% by weight of PTFE is prepared. This ink is applied and impregnated on carbon paper (TGPH060H manufactured by Toray Industries, Inc.) serving as a base material for the gas diffusion layers 113a and 113c, and heat-treated at 300 ° C. using a hot air drier to form the gas diffusion layer 13a. , 13c (about 200 μm).

  The gas diffusion layers 13a and 13c and the catalytic reaction layers 12a and 12c thus manufactured are joined to both surfaces of the polymer electrolyte membrane 111 (Nafion 112 electrolyte membrane manufactured by DuPont, USA) to complete the MEA 117.

  In such a catalyst material system of the fuel cell power generation device 1100, the fuel cell 121 is started (power generation) stopped up to 4000 times and described in Embodiments 6 to 8 together with a comparative example in which the humidification raw material purge process is not performed. The changes in the MEA voltage in the example of the purging process of the humidified raw material gas are summarized in the following table. In FIG. 23, the horizontal axis indicates the number of start and stop of the fuel cell, and the vertical axis indicates the voltage of the MEA 117, and the state of the voltage change of the MEA 17 in the humidified raw material purge processing example (Eighth Embodiment) and the comparative example is shown. It is shown.

  According to the purging process using the humidified raw material gas in the sixth to eighth embodiments, local combustion or the like based on repeated operations of power generation and stop can be prevented, so that the deterioration of the MEA 117 is suppressed and long-term without depending on the number of start / stop times. The voltage of the fuel cell 121 is stably maintained.

  On the other hand, in the comparative example, the catalyst deterioration of the MEA 117 proceeds due to local combustion or the like, and a slight decrease in the voltage of the MEA 117 is observed after the number of start / stops is 1000 times or more. As a result of destruction (perforation), the voltage of the MEA 117 sharply decreases.

  In each of the above embodiments, the fuel cell power generator 1100 corresponds to the fuel cell system of the present invention, the fuel cell 121 corresponds to the fuel cell of the present invention, and the fuel gas supply pipe 161 corresponds to the fuel gas of the present invention. The first switching valve 129 corresponds to a pipe and corresponds to the fuel gas on-off valve of the present invention, and these constitute the fuel gas supply means of the present invention.

  The oxidant gas supply pipe 162 corresponds to the oxidant gas pipe of the present invention, the second shut-off valve 131 corresponds to the oxidant gas on / off valve of the present invention, and these constitute the oxidant gas supply means of the present invention. To do.

  The source gas supply pipe 151 and the pipe connecting the third switching valve 143 and the cathode side inlet of the fuel cell 121 correspond to the source gas pipe of the present invention, and the third switching valve 143 is It corresponds to the raw material gas on-off valve of the present invention, and these constitute the raw material gas supply means of the present invention.

  The second switching valve 152 corresponds to the anode-side off-gas on / off valve of the present invention, and the second connection pipe 153 corresponds to the anode-side exhaust pipe of the present invention. The fourth switching valve 144 corresponds to the cathode-side off-gas on / off valve of the present invention, and the second circulation pipe 146 corresponds to the cathode-side exhaust pipe of the present invention.

  Further, the second circulation pipe 146 corresponds to the additional raw material gas pipe of the present invention, and the fourth switching valve 144 and the second switching valve 142 correspond to the additional raw material gas on / off valve of the present invention. The control unit 127 corresponds to the control means of the present invention.

  The above sixth to eighth embodiments may correspond to the following embodiments of the invention. That is, as a first invention, a fuel cell having a fuel gas channel and a source gas supply means for supplying a source gas are provided, and during the power generation period of the fuel cell, the source gas is introduced into the fuel gas channel. In the fuel cell transition period between the stop period and the power generation period in the fuel cell in which the fuel cell is generated by supplying the generated fuel gas and alternately stops and generates power, the raw material gas supply is performed. The fuel cell power generator may be configured to humidify the raw material gas sent from the means and expose the inside of the fuel cell to the humidified raw material gas atmosphere.

  As a second invention, the fuel cell power generator according to the first invention may be configured such that the electrolyte gas inside the fuel cell is exposed to the atmosphere of the source gas by circulating the source gas through the fuel gas passage. .

  As a third aspect of the invention, the fuel cell power generator according to the second aspect of the invention may humidify the source gas so that the dew point of the source gas can be maintained at or above the operating temperature of the fuel cell.

  According to a fourth aspect of the present invention, the source gas supply means includes a gas cleaning unit, and after the sulfur component in the source gas is removed by the gas cleaning unit, the inside of the fuel cell is exposed to the atmosphere of the source gas. The fuel cell power generator according to any one of the first to third aspects may be used.

  As a fifth invention, the raw material gas may be a fuel cell power generator according to the fourth invention, which is any one of methane gas, propane gas, butane gas, and ethane gas.

  Further, as a sixth aspect of the invention, a fuel generator that generates fuel gas to be supplied to the fuel cell from the source gas and water vapor supplied from the source gas supply means is provided, and the source gas supply means is provided during the transition period. In the first aspect of the present invention, the temperature of the fuel generator is maintained lower than the lower limit temperature at which the raw material gas is carbonized in the fuel generator when the raw material gas sent from is humidified inside the fuel generator. The fuel cell power generator may be used.

  As a seventh aspect of the invention, the fuel cell power generator according to the sixth aspect of the invention may be configured such that the temperature of the fuel generator is maintained at 300 ° C. or lower.

  As an eighth aspect of the invention, an anode and a cathode sandwiching an electrolyte membrane are disposed inside the fuel cell, and after exposing the anode to the source gas atmosphere, the cathode is exposed to the source gas atmosphere. The fuel cell power generator according to the invention may be used.

  Further, as a ninth aspect of the invention, a fuel generator that generates fuel gas to be supplied to the fuel cell from the source gas and water vapor supplied from the source gas supply means is provided, and the source gas is supplied to the fuel generator. The fuel cell power generator according to the eighth aspect of the present invention may be humidified internally.

  According to a tenth aspect of the invention, an anode and a cathode sandwiching an electrolyte membrane are disposed inside the fuel cell, and the cathode is exposed to the source gas atmosphere, and then the anode is exposed to the source gas atmosphere. The fuel cell power generator according to the invention may be used.

  Further, as an eleventh aspect of the invention, a fuel according to the tenth aspect of the invention is provided with a humidifier that humidifies an oxidant gas for power generation reaction with the fuel gas supplied to the cathode, and the source gas is humidified by the humidifier. It is good also as a battery power generation device.

  According to a twelfth aspect of the invention, an anode and a cathode sandwiching an electrolyte membrane are disposed inside the fuel cell, and the cathode is exposed to an atmosphere of the first source gas that is diverted from the source gas, and the anode is The fuel cell power generator according to the first aspect of the present invention may be exposed to the atmosphere of the second source gas that is diverted from the source gas.

  According to a thirteenth aspect of the invention, a fuel generator for generating fuel gas to be supplied to the fuel cell from the source gas and water vapor supplied from the source gas supply means, and an oxidant gas to be supplied to the cathode are humidified. A fuel cell power generator according to a twelfth aspect of the invention may further include a humidifier, wherein the first source gas is humidified inside the humidifier, and the second source gas is humidified inside the fuel generator.

  Further, as a fourteenth aspect of the invention, the fuel cell power generation device according to the first aspect of the present invention may include an electrolyte membrane inside the fuel cell, and start the power generation period based on the conductivity of the electrolyte membrane.

  The fifteenth aspect of the invention may be the fuel cell power generation apparatus of the fourteenth aspect of the invention in which the power generation period is started based on the conductivity of the electrolyte membrane corresponding to a predetermined relative humidity inside the fuel cell.

(Embodiment 9)
A fuel cell system according to Embodiment 9 of the present invention will be described with reference to FIG. FIG. 24 is a configuration diagram of the fuel cell system of the present embodiment.

  The fuel cell stack 201 is configured by stacking a plurality (n) of single cells (C1 to Cn). The unit cell includes a hydrogen ion conductive polymer electrolyte membrane, a pair of electrodes sandwiching the electrolyte membrane, and a pair of separator plates each having a gas flow path for supplying fuel gas and oxidant gas to the pair of electrodes.

  On the air electrode side of the fuel cell stack, an oxidant gas control device 202 that controls the supply amount of the oxidant gas based on the voltage and internal resistance of the fuel cell stack, and a total heat exchange type humidification as a humidifier for humidifying the oxidant gas An oxidant gas supply pipe 2013 in which a vessel 209 and a hot water humidifier 2010 are installed is connected.

  On the other hand, the fuel electrode side is connected to a fuel gas supply pipe 2012 provided with a fuel generator 203 that generates fuel gas from the source gas and a gas cleaning unit 208 that cleans the source gas.

  The fuel gas supply pipe 2012 and the oxidant gas supply pipe 2013 are provided with solenoid valves 2071 to 2079 for switching gas flow paths. A power circuit unit 6 is connected to a current collecting plate (not shown) of the fuel cell stack 1, the voltage of each cell (C1 to Cn) is detected by the voltage detector 204, and the internal resistance of the cell is a high frequency resistance. It is measured by a measuring unit such as 2011. The control unit 205 controls the fuel cell stack, the fuel generator, the gas cleaning unit, the humidification unit, the power circuit unit, and the measurement unit, and in particular, is output from the power circuit unit 206 based on the detected voltage and internal resistance. The amount of electric power generated, the amount of fuel gas generated by the fuel generator 203, and the opening / closing of the valves in the electromagnetic valves 2071 to 2079 are controlled.

  Next, an operation method of the fuel cell system of the present embodiment described above will be described with reference to Table 2 and FIGS. Table 2 shows a process (sequence) of the operation method of the fuel cell system of the present embodiment, and FIGS. 25 to 29 respectively show the average value of the internal resistance of the unit cell and the temperature of the fuel cell stack in each step of Table 2. The transition of the average value of the generated power and the voltage of the unit cell is shown. Here, a case where 70 unit cells are stacked (when n = 70) is shown.

  First, during normal operation (step 1), humidified air is supplied to the air electrode, and humidified reformed gas (SRG) is supplied to the fuel electrode to generate power. At this time, the battery temperature is 70 ° C., the average voltage of each unit cell is about 0.75 V, and the generated power is 1 kW.

When stopping the operation of the fuel cell system, the process includes a step (1) of supplying the inert gas dried before the stop to the fuel cell stack and setting the internal resistance of the unit cell to 1.0 Ω · cm ² or more. Perform the operation.

  By this operation, the formation of the local battery in the electrode can be suppressed at the time of stopping. Even when oxygen is introduced from the outside during shutdown, the proton conductivity of the polymer electrolyte membrane is low and the reactivity is low. Therefore, oxidation of the air electrode, adsorption of impurities to the air electrode, and elution of catalyst components at the fuel electrode It is possible to suppress electrode deterioration due to.

The internal resistance of the unit cell in step (1) is preferably 1.0 to 3.0 Ω · cm ² . If it exceeds 3.0 Ω · cm ² , the change in water content will increase and the volume change due to repeated swelling and shrinkage of the polymer electrolyte membrane will increase when drying at stop and humidification at startup are repeated. , The electrode is easily damaged.

  First, in step 2, the gas supplied to the air electrode is switched to a dry inert gas, and external output is stopped. At this time, the battery voltage gradually decreases, and the average voltage of the unit cells is about 0.10 to 0.15V. This is because the inside of the air electrode is replaced with an inert gas, and hydrogen in the fuel electrode naturally diffuses into the air electrode, so that the potentials of both electrodes approach each other. Note that in the configuration of a normal fuel cell, the flow volume of the air electrode and the flow volume of the fuel electrode are almost the same, and when hydrogen and oxygen diffuse and react, there is an excess of hydrogen. It approaches 0V with respect to the standard hydrogen electrode.

Next, in step 3, dry inert gas is supplied to both electrodes until the internal resistance of the unit cell in the fuel cell stack becomes 1.0 Ω · cm ² or more. In steps 2 and 3, the temperature of the fuel cell stack is maintained at 70 ° C.

  That is, in Table 1, step (1) described above corresponds to step 3.

In Step 4 where the internal resistance of the unit cell in the fuel cell stack is 1.0 Ω · cm ² or more, the gas flow paths of the fuel electrode and the air electrode are sealed, the gas flow is stopped, the battery temperature is lowered, and the operation is performed. To stop.

When starting the operation of the fuel cell system, an operation including the step (2) of supplying a humidified inert gas to the fuel cell stack before starting the power generation and setting the internal resistance of the unit cell to 0.3 Ω · cm ² or less. I do. By this operation, an increase in internal resistance due to heat generation can be suppressed during startup.

The internal resistance of the unit cell in step (2) is preferably 0.1 to 0.3 Ω · cm ² . The internal resistance of the cell during operation is about 0.1 Ω · cm ² .

In step 5, the humidified inert gas is supplied to the air electrode and the fuel electrode while the temperature of the fuel cell stack is increased until the internal resistance of the single cell in the fuel cell stack becomes 0.3 Ω · cm ² or less. By this step 5, the polymer electrolyte membrane which was in a dry state during the stop is humidified, and the fuel cell stack returns to a state where power generation is possible.

  That is, in Table 1, step (2) described above corresponds to step 5.

  In step 6, the gas supplied to the fuel electrode is switched to humidified reformed gas (SRG), and the unit cell is operated for a while with the average voltage of the cell being about 0.10 to 0.15V. At this time, hydrogen moves from the fuel electrode to the air electrode by natural diffusion, whereby the electrode catalyst is reduced and cleaned.

  In step 7, the gas supplied to the air electrode is switched to humidified air to generate 1 kW of power.

  When operated by the above method, it is possible to suppress deterioration of the fuel cell stack due to repeated start / stop of operation.

  As the inert gas used above, the raw material gas cleaned by the gas cleaning unit 208 can be used. For example, when a city gas containing methane, propane, or the like is used as a source gas, a purified gas obtained by removing an odorant (S component) contained in the city gas as an impurity is used as an inert gas. This removal of impurities is performed to prevent poisoning of Pt contained in the catalyst layer.

  As the dry inert gas used in Steps 2 and 3, for example, the raw material gas that has passed through the bypass 203b provided between the fuel generators 203 via the gas cleaning unit 208 is used.

  The humidified inert gas used in steps 5 and 6 is, for example, a raw material gas that has passed through the fuel generator 203 at 300 ° C. or lower via the gas cleaning unit 208. When the temperature of the fuel generator 203 is 300 ° C. or lower, the raw material gas is not reformed into a hydrogen-containing gas, and only the raw material gas is humidified.

  In addition, in the humidified inert gas, for example, the raw material gas that has passed through the connecting pipe 2012a that connects the fuel gas supply pipe and the air supply pipe after being passed through the gas cleaning unit 208 is generated in the fuel generator 203. What was humidified with the hot water humidifier 2010 using heat and water can be used.

  Further, the raw material gas supplied to the fuel cell stack 201 as an inert gas can be reused as a combustion fuel in the fuel generator 203.

  Since the source gas can be used as the inert gas in this way, it is not necessary to separately provide an apparatus for supplying an inert gas such as a nitrogen gas cylinder. Therefore, deterioration of the fuel cell stack can be easily suppressed without complicating the fuel cell system and without cost.

  Examples of the present invention will be specifically described below, but the present invention is not limited to them.

(Example)
A fuel cell stack having the configuration shown in FIG. 29 was produced by the following method. FIG. 29 is a schematic longitudinal sectional view showing a part of the fuel cell stack.
(1) Production of membrane / electrode assembly Acetylene black (Denka Black manufactured by Denki Kagaku Kogyo Co., Ltd., particle size: 35 nm) as carbon powder and aqueous dispersion of polytetrafluoroethylene (PTFE) (Daikin Kogyo Co., Ltd.) A water repellent ink containing 20% by weight of PTFE as a dry weight was obtained by mixing with D1). This ink was applied and impregnated on carbon paper (TGPH060H manufactured by Toray Industries, Inc.) as a base material for a gas diffusion layer, and then heat-treated at 300 ° C. with a hot air dryer, and a gas diffusion having a thickness of about 200 μm. Layers 2023a and 2023b were obtained.

  On the other hand, Pt was supported as a catalyst on Ketjen Black (Ketjen Black EC manufactured by Ketjen Black International Co., Ltd., particle size 30 nm) as carbon powder to obtain a catalyst powder containing 50% by weight of Pt. This catalyst powder was mixed with hydrogen ion conductive polymer electrolyte and binder perfluorocarbon sulfonic acid ionomer (Aldrich, USA, 5 wt% Nafion dispersion) in a weight ratio of 2: 1. The mixture was molded to form catalyst layers 2022a and 2022b having a thickness of 10 to 20 μm.

  The catalyst layers 2022a and 2022b and the gas diffusion layers 2023a and 2023b obtained above were bonded to both surfaces of the hydrogen ion conductive polymer electrolyte membrane 21 (manufactured by DuPont, Nafion 112 membrane). The membrane is composed of the polymer electrolyte membrane 21, the anode 2024a composed of the catalyst layer 2022a and the gas diffusion layer 2023a, and the cathode 2024b composed of the catalyst layer 2022b and the gas diffusion layer 2023b, which sandwich the polymer electrolyte membrane 21. An electrode assembly (hereinafter referred to as MEA) 2027 was obtained.

At this time, a rubber gasket 2025 was joined to the outer peripheral edge portion of the polymer electrolyte membrane 2021 in the MEA 2027. The gasket 2025 has a manifold hole through which fuel gas, oxidant gas, and cooling water flow.
(2) Assembly of fuel cell stack An anode side separator plate 2026a having a gas flow path 2028a having a depth of 0.5 mm for supplying fuel gas to the anode 2024a, and a depth of 0.5 mm for supplying oxidant gas to the cathode 2024b A cathode separator plate 2026b having a gas flow path 2028b was prepared. As the separator plates 2026a and 2026b, graphite plates impregnated with a phenol resin having an outer size of 20 cm × 32 cm × 1.3 mm were used. Further, a cooling water channel 2029 having a depth of 0.5 mm is formed on the surface opposite to the surface having the gas channel.

  The surface of the anode separator plate 2026a having the gas flow path 2028a is superimposed on the surface of the anode 2024a in the MEA 2027, and the surface of the cathode separator plate 2026b having the gas flow path 2028b is superimposed on the surface of the cathode 2024b of the MEA 2027. A battery was obtained. 70 unit cells were stacked to obtain a battery stack. At this time, the surface of the separator 2026a having the cooling water flow path 2029 and the surface of the separator 2026b having the cooling water flow path 2029 were overlapped to form a cooling unit for each single cell. In addition, a rubber seal portion 2030 is provided on the surface of the separator plate having the cooling portion so as to surround the cooling water flow path in order to prevent the cooling water from flowing out.

Then, a stainless steel current collector plate, an insulating plate made of an electrically insulating material, and an end plate were disposed at both ends of the battery stack, and the whole was fixed with a fastening rod, thereby producing a fuel cell stack. The fastening pressure at this time was 15 kgf / cm ² per area of the separator plate.

[Evaluation of fuel cell system]
Then, the fuel cell stack 201 obtained above was connected to the fuel cell system having the same configuration as in FIG. 24 described above, and the following operation test was performed in the same process as in Table 2 described above.

  As Step 1, 13A gas as source gas and air as oxidant gas were supplied to the fuel gas supply pipe and oxidant gas supply pipe in the fuel cell system obtained above. At this time, the cell temperature in the fuel cell stack was 70 ° C., the fuel gas utilization rate (Uf) was 70%, and the air utilization rate (Uo) was 40%. The fuel gas and air were humidified so as to have dew points of 65 ° C. and 70 ° C., respectively. As the purge gas, 13A gas that passed through the gas cleaning unit 8 was used.

  Then, the times of Steps 1 to 6 in Table 2 described above are respectively set to Step 1:80 minutes, Step 2:20 minutes, Step 3:30 minutes, Step 4:48 hours, Step 5:30 minutes, and Step 6: Steps 1-6 were performed 100 cycles for 20 minutes. The operation test was performed at room temperature (27 ° C.) (Experiment No. 1).

  In addition, the raw material gas cleaned in the gas purification part was used for the dry inert gas. Moreover, the raw material gas which passed the fuel generator below 300 degreeC was used for the humidified inert gas.

  An operation test was performed in the same manner as in Experiment No. 1 except that the time of Steps 1 to 6 was changed to the conditions shown in Table 3.

During normal operation (step 1), the internal resistance of the unit cell was 0.1 Ω · cm ² in any of the execution numbers 1 to 12.

  First, Table 3 shows the results of the operation test in execution numbers 1, 2, and 6 to 8 in which the time of step 3 is changed. In addition, the internal resistance in Table 4 shows the average value of the internal resistance of each unit cell at the end of Steps 3 and 5. Moreover, a deterioration rate shows the average value of the fall of the voltage of each single cell per cycle (steps 1-6) when starting and a stop are repeated alternately.

  Under these conditions where the time of step 3 is different, different results were obtained for internal resistance during shutdown.

Here, in order for the generated power of the fuel cell stack to have a merit as a running cost with respect to the power of a general large power plant, deterioration due to repeated start and stop, that is, the voltage drop is about 80 mV or less in about 4000 cycles, that is, The allowable range is 20 μV / cycle or less. In execution numbers 1 and 2 in which the internal resistance at the time of stop was 1.0 to 3.0 Ω · cm ² , the voltage drop of the fuel cell stack was suppressed.

On the other hand, in Experiment Nos. 6 and 7 in which the internal resistance at the time of stop was 1.0 Ω · cm ² or less, the voltage drop was large. This is presumably because the dry state at the time of stoppage was insufficient, so that pores were clogged by humidified water inside the electrode, a local battery was formed, and the electrode was deteriorated. In Experiment No. 8 where the internal resistance at the time of stop was 10 Ω · cm ² , the voltage was significantly reduced.
This is thought to be because the volume change due to repeated swelling and shrinkage of the polymer electrolyte membrane was large and the electrode was damaged because the change in the amount of water due to repeated drying at stop and humidification at startup was too large. It is done.

  Next, Table 5 shows the results of the operation tests of execution numbers 1, 3, 9 and 10.

Under these conditions in which the temperature raising / wetting time in Step 5 was different, the results of different internal resistance values at the start were obtained. In implementation numbers 1 and 3 in which the internal resistance at startup was 0.3 Ω · cm ² or less, the voltage drop was suppressed.

  On the other hand, in the experiment numbers 9 and 10 in which the internal resistance at the start exceeds 0.3, the voltage drop was large. This is considered to be because the proton conductivity of the polymer electrolyte membrane is low, the reaction resistance is increased, and the polymer electrolyte membrane is deteriorated by starting power generation with a high internal resistance at the time of startup.

  Next, Table 6 shows the results of the operation test of execution numbers 1, 2, 4 to 8, 11, and 12.

Run numbers 1 and 4 and experiment numbers 2 and 5 differed in the stop time of step 4, but the voltage drop was small regardless of the length of the stop time, and the deterioration of the fuel cell stack was suppressed.

  In contrast, in Experiment Nos. 6 and 11 and Experiment Nos. 7 and 12, the stop time was longer, and in Experiment Nos. 11 and 12, the voltage drop was larger. This is presumably because, under these drying conditions in Step 3, the drying before the stop was insufficient, a local battery was formed inside the electrode, and the deterioration of the electrode progressed as the stop time increased.

  In this example, Nafion 112 was used as the polymer electrolyte membrane, but the same effect was obtained with other materials used as the polymer electrolyte membrane. Further, in this example, the test temperature was set to room temperature of 27 ° C. However, even at other temperatures, for example, Reference 1 (Handbook of Fuel Cell, vol. 3, p567, Fundamentals, Technology and Applications) described in Nafion 112 The effective internal resistance range according to the present invention can be calculated from the conductive Arrhenius plot.

The ninth embodiment may correspond to the following embodiment of the invention. That is, as a first invention, a pair of separators having a hydrogen ion conductive polymer electrolyte membrane, a pair of electrodes sandwiching the electrolyte membrane, and a flow path for supplying fuel gas and oxidant gas to the pair of electrodes, respectively A fuel cell stack in which a plurality of single cells made of plates are stacked;
A fuel generator for generating the fuel gas from the raw material gas;
A gas cleaning unit for cleaning the source gas;
A humidifying section for humidifying the oxidant gas;
A power circuit unit for extracting power from the fuel cell stack;
A measurement unit that measures the voltage and resistance of the unit cell; and a control unit that controls the fuel cell stack, a fuel generator, a gas cleaning unit, a humidification unit, a power circuit unit, and a measurement unit,
The fuel cell system may have an internal resistance of 1.0 Ω · cm ² or more when the operation of the fuel cell system is stopped.

  As a second invention, the measurement unit may be the fuel cell system according to the first aspect provided with a high frequency resistance meter.

According to a third aspect of the present invention, the control unit supplies dry inert gas to the fuel cell stack while maintaining the temperature of the operation before stopping the operation of the fuel cell system. The fuel cell system according to the first aspect of the present invention may control the internal resistance of the unit cell to 1.0 Ω · cm ² or more.

  As a fourth invention, the control unit may be a fuel cell system according to a third invention that supplies a dry inert gas to the fuel cell stack while maintaining the temperature of the operation.

As a fifth aspect of the invention, the control unit supplies the humidified inert gas to the fuel cell stack before starting the operation of the fuel cell system, thereby reducing the internal resistance of the unit cell to 0. The fuel cell system of the first invention may be controlled to 3 Ω · cm ² or less.

  Further, as a sixth invention, the fuel cell system according to any one of the third to fifth inventions, wherein the inert gas is a raw material gas purified by the gas cleaning unit.

  As a seventh invention, the fuel cell system according to the fifth invention may be configured such that the inert gas is a humidified raw material gas generated at a temperature of 300 ° C. or lower in the fuel generator at the time of startup.

  According to an eighth aspect of the invention, there is provided the fuel cell system according to the fifth aspect, wherein the inert gas is a raw material gas humidified in the humidifying section using heat and water generated in the fuel generator at the time of startup. Also good.

  Further, as a ninth invention, the fuel cell system according to any one of the sixth to eighth inventions is used as a fuel for combustion of the fuel generator after the source gas is supplied to the fuel cell stack. Good.

Further, as a tenth invention, a pair of hydrogen ion conductive polymer electrolyte membranes, a pair of electrodes sandwiching the electrolyte membrane, and a pair of gas flow paths for supplying fuel gas and oxidant gas to the pair of electrodes, respectively. A method of operating a fuel cell system comprising a fuel cell stack in which a plurality of single cells made of separator plates are laminated,
Before stopping the operation of the fuel cell system, including a step (1) of supplying a dry inert gas to the fuel cell stack so that the internal resistance of the unit cell is 1.0 Ω · cm ² or more. A method of operating a fuel cell system characterized by the above.

  As an eleventh aspect of the invention, in the step (1), the fuel cell system may be operated at the operating temperature in the tenth aspect of the invention.

As a twelfth aspect of the invention, before starting the operation of the fuel cell system, humidified inert gas is supplied to the fuel cell stack so that the internal resistance of the unit cell is 0.3 Ω · cm ² or less. A method for operating the fuel cell system according to the tenth aspect including the step (2) may be employed.

  The thirteenth invention includes a step (3) for purifying the source gas, and in the steps (1) and (2), the purified source gas is used as the inert gas in the tenth or twelfth aspect. It is good also as the operating method of the fuel cell system of invention.

  The fourteenth invention includes a step (4) of generating the fuel gas from a source gas and a step (5) of humidifying the source gas. In the step (2), the humidified source gas is converted into the inert gas. It is good also as an operating method of the fuel cell system of the 12th invention used as gas.

  The fifteenth aspect of the invention may be the operating method of the fuel cell system of the fourteenth aspect of the invention in which the heat and water generated in the step (4) are used to humidify the source gas in the step (5).

(Embodiment 10)
First, the configuration of the fuel cell power generator according to the present embodiment will be described with reference mainly to FIGS.

  FIG. 30 shows a basic configuration of a polymer electrolyte fuel cell (hereinafter referred to as PEFC) among the fuel cells according to Embodiment 10 of the present invention.

  In a fuel cell, a fuel gas such as hydrogen and an oxidant gas such as air are electrochemically reacted by a gas diffusion electrode, and electricity and heat are generated simultaneously.

  The side involving a fuel gas such as hydrogen is referred to as the anode, and the sign of the related means is a, the side involving the oxidant gas such as air is called the cathode, and the sign of the related means is c.

  Reference numeral 301 denotes an electrolyte, which is used by a polymer electrolyte membrane or the like that selectively transports hydrogen ions. Catalytic reaction layers 302a and 302c mainly composed of carbon powder carrying a platinum-based metal catalyst are disposed in close contact with both surfaces of the electrolyte 1 (hereinafter also referred to as a membrane). In the catalytic reaction layer, the reactions shown in the above (Chemical Formula 1) and (Chemical Formula 2) occur.

  The fuel gas containing at least hydrogen (hereinafter referred to as anode gas) performs the reaction shown in (Chemical Formula 1) (hereinafter referred to as anode reaction).

  The hydrogen ions moved through the electrolyte 1 undergo a reaction shown in (Chemical Formula 2) (hereinafter referred to as a cathode reaction) in an oxidant gas (hereinafter referred to as a cathode gas) and a catalytic reaction layer 302c to generate water. At this time, electricity and heat are generated.

  Furthermore, diffusion layers 303a and 303c having both gas permeability and conductivity are disposed in close contact with the outer surfaces of the catalyst reaction layers 302a and 302c. The diffusion layers 303a and 303c and the catalyst reaction layers 302a and 302c constitute electrodes 304a and 304c.

  Reference numeral 305 denotes a membrane electrode assembly (hereinafter referred to as MEA), which is formed by electrodes 304 a and 304 c and an electrolyte 301.

  A gas flow path for mechanically fixing the MEA 305, electrically connecting adjacent MEAs 305 to each other in series, supplying a reactive gas to the electrode, and carrying away a gas generated by the reaction or surplus gas A pair of conductive separators 307a and 307c formed on the surface in contact with the MEA 5 with 306a and 306c are disposed.

  A basic fuel cell (hereinafter referred to as a cell) includes a membrane 301, a pair of catalytic reaction layers 302a and 302c, a pair of diffusion layers 303a and 303c, a pair of electrodes 304a and 304c, and a pair of separators 307a and 307c. Form.

  The separators 307a and 307c are in contact with the separator 307c or the separator 307a of the adjacent cell on the surface opposite to the MEA 305.

  308a and 308c are cooling water passages provided on the side where the separators 307a and 307c are in contact with each other, and the cooling water flows there. The cooling water moves heat so as to adjust the temperature of the MEA 305 through the separators 307a and 307c.

  Reference numeral 309 denotes an MEA gasket that seals the MEA 305 and the separators 307a and 307c.

  The membrane 301 has a fixed charge, and hydrogen ions exist as a counter ion of the fixed charge. The membrane 301 is required to have a function of selectively permeating hydrogen ions. For this purpose, the membrane 301 needs to retain moisture. This is because when the film 301 contains moisture, the fixed charge fixed in the film 301 is ionized, and hydrogen, which is a counter ion of the fixed charge, is ionized and can move.

  FIG. 31 is a perspective view of a stack in which cells are stacked.

  Since the voltage of the fuel battery cell is usually as low as about 0.75 V, a plurality of cells are stacked in series so as to obtain a high voltage.

  Reference numeral 3021 denotes a current collecting plate for taking out current from the stack, and reference numeral 3022 denotes an insulating plate for electrically insulating the cell from the outside. Reference numeral 3023 denotes an end plate that fastens and mechanically holds a stack of stacked cells.

  FIG. 32 is a diagram illustrating the fuel cell power generator according to Embodiment 1 of the present invention.

  Reference numeral 3031 denotes an outer casing of the fuel cell system.

  A cleaning unit 3032 removes substances that adversely affect the fuel cell from the fuel gas, and guides the fuel gas from the raw material gas pipe.

  A gate valve 3033 controls the flow of the source gas.

  A fuel generator 3034 generates a fuel gas containing at least hydrogen from the raw material gas.

  During the operation of the fuel cell, the raw material gas is led to the fuel generator 3034 through the raw material gas pipe and the gate valve 3035.

  Reference numeral 3036 denotes a stack, which is shown in detail in FIGS. The fuel gas is led from the fuel generator 3034 to the fuel cell stack 3036 through the fuel gas pipe.

  A gate valve 3037 controls the flow of fuel gas to the fuel cell stack 3036. Further, the gate valve 3037 functions to purge and seal the inert gas in the stack during stop storage. Further, the gate valve 3037 functions to purge and seal the inert gas in the stack during stop storage.

  The inert gas is not necessarily a so-called noble gas such as helium or neon or nitrogen, but may be a gas inert to the fuel cell such as a raw material gas cleaned in the gas cleaning section. In short, it is a predetermined purge gas (the same applies hereinafter).

  3039 is a blower, and the oxidant gas is introduced into the fuel cell stack 3036 through the intake pipe.

  Reference numeral 3041 denotes a gate valve that controls the flow of fuel gas to the fuel cell stack 3036.

  The oxidant gas that has not been used in the fuel cell stack 3036 is exhausted through the gate valve 3042. In addition, the gate valve 3042 functions to purge and seal the inert gas in the stack during stop storage.

  Reference numeral 3040 denotes a humidifier. Since the fuel cell needs moisture, the oxidant gas flowing into the fuel cell stack 3036 is humidified here.

  The fuel gas not used in the fuel cell stack 3036 flows again into the fuel generator 3034 through the off-gas pipe. The gas from the off-gas pipe is used for combustion or the like, and is used for an endothermic reaction or the like for generating a fuel gas from the raw material gas.

  During stop storage, the gate valve 3042 serves to purge and seal the inert gas in the stack.

  Reference numeral 3043 denotes a gate valve, which controls off-gas flowing from the fuel cell stack 3036 to the fuel generator 3034.

  3044 is a power circuit unit that extracts power from the fuel cell stack 3036, and 3045 is a control unit that controls the gas, the power circuit unit, the gate valve, and the like.

  Reference numeral 3046 denotes a pump that allows water to flow from the cooling water inlet pipe to the water path of the fuel cell stack 3036. The water that has flowed through the fuel cell stack 3036 is transported to the outside from the cooling water outlet pipe. By flowing water through the fuel cell stack 3036, the generated heat can be used outside the fuel cell system while keeping the heated fuel cell stack 303036 at a constant temperature.

  The oxygen concentration detectors 3050 and 3051 detect a change in the oxygen concentration of the inert gas filled in the fuel cell stack 3036. When an oxygen concentration exceeding a predetermined concentration is detected, a signal is transmitted to the control unit 3045 to operate the gate valve. I do.

  The fuel cell power generator according to the tenth embodiment includes a fuel cell stack 3036 composed of fuel cells, a gas cleaning unit 3032, a fuel generator 3034, a power circuit unit 3044, a control unit 3045, and an oxygen concentration detector. Has been.

  The means including the oxygen concentration detectors 3050 and 3051 corresponds to the oxygen concentration detection means of the present invention, the control unit 3045 corresponds to the purge gas injection means of the present invention, and the fuel cell power generator of the present embodiment is This corresponds to the fuel cell operating device of the present invention.

  The gas cleaning unit 3032 corresponds to the fuel gas cleaning means of the present invention.

  The gate valve 3041 corresponds to the oxidant gas flow path upstream valve of the present invention, the gate valve 3042 corresponds to the oxidant gas flow path downstream valve of the present invention, and the gate valve 3037 corresponds to the fuel gas flow path upstream of the present invention. Corresponding to the valve, the gate valve 3043 corresponds to the fuel gas flow path downstream valve of the present invention.

  Next, the operation of the fuel cell power generator of this embodiment will be described. While describing the operation of the fuel cell power generator of the present embodiment, an embodiment of the fuel cell operation method of the present invention will also be described (the same applies hereinafter).

  First, a basic operation will be described, and an operation related to storage, which is a point of the fuel cell power generation device of the present embodiment, will be described later.

  In FIG. 32, the valve 3033 is opened, and the source gas flows from the source gas pipe into the gas cleaning unit 3032.

  As the raw material gas, a hydrocarbon-based gas such as natural gas or propane gas can be used. In this embodiment, 13A, which is a mixed gas of methane, ethane, propane, and butane gas, is used.

  As the gas cleaning part 32, a member for removing gas odorant such as TBM (tertiary butyl mercaptan), DMS (dimethyl sulfide), THT (tetrahydrothiofin) is used. This is because sulfur compounds such as odorants are adsorbed on the catalyst of the fuel cell to become a catalyst poison and inhibit the reaction.

  In the fuel generator 34, hydrogen is generated by the reaction shown in (Chemical Formula 9).

(Chemical 9)
CH ₃ + H ₂ O → 3H ₂ + CO (−203.0 KJ / mol)
Here, a fuel gas containing hydrogen and moisture is created and flows into the fuel cell stack 3036 of the fuel cell via the fuel gas pipe.

  The oxidant gas passes through the humidifier 3040 by the blower 3039 and then flows into the fuel cell stack 3036. The exhaust gas of the oxidant gas is discharged outside through the exhaust pipe.

  As the humidifier 3040, one that flows an oxidant gas into warm water, one that blows water into the oxidant gas, or the like can be used. In this embodiment, a total heat exchange type is used. This is to move water and heat in the exhaust gas into an oxidant gas as a raw material carried from the intake pipe when passing through the humidifier 3040.

  The cooling water is flowed from the cooling water inlet pipe to the water path of the fuel cell stack 3036 from the pump 3046, and then water is carried to the outside from the cooling water outlet pipe. Although not shown in FIG. 32, a normal water heater or the like is piped in the cooling water inlet pipe or the cooling water outlet pipe. The heat generated in the fuel cell stack 3036 of the fuel cell is taken out and can be used for hot water supply or the like.

  The operation of the fuel cell in the fuel cell stack 3036 will be described with reference to FIG.

  An oxidant gas such as air is supplied to the gas flow path 306c, and a fuel gas containing hydrogen is supplied to the gas flow path 306a.

  Hydrogen in the fuel gas diffuses through the diffusion layer 303a and reaches the catalytic reaction layer 302a. In the catalytic reaction layer 302a, hydrogen is divided into hydrogen ions and electrons. The electrons are moved to the cathode side through an external circuit. Hydrogen ions permeate the membrane 301, move to the cathode side, and reach the catalytic reaction layer 302c.

  Oxygen in an oxidant gas such as air diffuses through the diffusion layer 303c and reaches the catalytic reaction layer 302c. In the catalyst reaction layer 302c, oxygen reacts with electrons to form oxygen ions, and the oxygen ions react with hydrogen ions to generate water. That is, the oxidant gas and the fuel gas react around the MEA 305 to generate water, and electrons flow.

  Further, heat is generated during the reaction, and the temperature of the MEA 305 increases.

  Therefore, the heat generated by the reaction is carried out by water by flowing water or the like through the cooling water paths 308a and 308c. That is, heat and current (electricity) are generated.

At this time, it is important to control the humidity of the introduced gas and the amount of water generated by the reaction. When there is little moisture, the membrane 301 is dried and the ionization of the fixed electrification is reduced, so that the movement of hydrogen is reduced, so that the generation of heat and electricity is reduced. On the other hand, if there is too much water, water accumulates around the MEA 305 or around the catalytic reaction layers 302a and 302c, and the supply of gas is hindered and the reaction is suppressed, so that the generation of heat and electricity is reduced. (Hereafter, this state is called flatting.)
The operation after the reaction in the fuel cell is described with reference to FIG.

  Exhaust gas in which the oxidant gas is not used is passed through a humidifier 3040 to transfer heat and moisture to the oxidant gas sent from the blower 3039 and then discharged to the outside.

  The off gas that has not been used for the fuel gas flows again into the fuel generator 3034 through the off gas pipe. The gas from the off gas pipe is used for combustion or the like in the fuel generator 3034. Since the reaction for generating the fuel gas from the raw material gas is an endothermic reaction as shown in (Chemical Formula 4), it is used as heat necessary for the reaction.

  The power circuit unit 44 serves to draw DC power from the fuel cell stack 36 after the fuel cell starts generating power.

  The control unit 3045 performs control so as to keep the control of other parts of the fuel cell system optimal.

  Next, the operation related to storage, which is a point of the fuel cell power generation device of the present embodiment, will be described more specifically.

  The source gas was city gas 13A, and the oxidant gas was air.

  The temperature of the fuel cell was 70 ° C., the fuel gas utilization rate (Uf) was 70%, and the oxygen utilization rate (Uo) was 40%.

  The fuel gas and air were each humidified to have a dew point of 70 ° C.

A current was taken out from the power circuit unit 3044. The current was adjusted to 0.2 A / cm ² per apparent area of the electrode.

  A hot water storage tank (not shown) is attached to the cooling water inlet pipe and the cooling water outlet pipe.

  The pump 3046 was adjusted so that the temperature of water in the cooling water inlet pipe was 70 ° C. and the temperature of water in the cooling water outlet pipe was 75 ° C.

  The start / stop and storage conditions were as follows.

  FIG. 34 shows changes in stack voltage and oxygen concentration.

  In the operation condition A, after performing a steady operation process, it moved to the stop process 1.

  The current from the stack is taken out by the power circuit unit 3044. When the voltage of a typical single cell of the fuel cell stack 3036 falls below 0.5V, the current take-out is stopped, and when the voltage exceeds 0.7V, the current is again drawn. Was controlled by the control unit 3045.

  In the stop process 1, the blower 3039 is stopped to stop the supply of air to the fuel cell stack 3036, the gate valve 3048 is opened, and a sulfur compound such as an odorant and a nitrogen compound such as ammonia and an amine substance are formed in the gas cleaning unit 3032. A raw material gas from which substances that adversely affect the fuel cell such as carbon monoxide were removed was fed from a pump 3049.

  Next, stop process 2 was performed.

  The gate valve 3035 is closed, the supply of the fuel gas from the fuel generator 3034 to the fuel cell stack 3036 is stopped, the gate valve 3047 is opened, and the gas purifier 3032 is used for sulfur compounds such as odorants, ammonia, amine substances, etc. A raw material gas from which substances that adversely affect the fuel cell such as nitrogen compounds and carbon monoxide were removed was flowed into the fuel cell stack 3036. The fuel gas pushed out from the fuel cell stack 3036 by the raw material gas from the fuel cell stack 3036 was returned to the fuel generator 3034 from the off-gas pipe, and the fuel gas in the fuel cell stack 3036 was replaced with the raw material gas.

  Next, stop process 3 was performed.

  In the stop step 3, the gate valve 3037 and the gate valve 3043 on the anode side are closed, the gate valve 3041 and the gate valve 3042 on the cathode side are closed, the fuel cell stack 3036 is filled and sealed with the raw material gas, and the pump 3049 is stopped. did. In addition, the pump 3046 was stopped and cooling water movement from the outside was eliminated.

  Next, it becomes the storage process 1. In the storage process 1, the temperature of the fuel generator 3034 and the fuel cell stack 3036 that are at a high temperature gradually decreases, and finally becomes the same as the external temperature.

  In the storage step 2, the oxygen concentration detectors 3050 and 3051 both detect an oxygen concentration of 10 ppm (corresponding to the lower limit value of the oxygen concentration that can be detected by a normal measurement method). The gate valve 3037 and the gate valve 3043 on the side are opened, the gate valve 3041 and the gate valve 3042 on the cathode side are opened, the pump 3049 is operated, and the raw material gas is reinjected into the fuel cell stack 3036 again. The gate valve 3037 and gate valve 3043 and the gate valve 3041 and gate valve 3042 on the cathode side were closed and sealed.

  In short, a sluice valve is installed upstream and downstream of the oxidant gas and fuel electrode in the oxidant gas and fuel gas supply passage, an oxygen concentration detector is disposed between both poles and the downstream sluice valve, and the oxygen concentration detector is predetermined. By detecting the concentration, the gate valves arranged upstream and downstream of both electrodes are opened and closed, and the inert gas is reinjected again.

  More specifically, by setting the oxygen concentration at which the oxygen concentration detector operates the gate valve to 10 ppm or more, it is possible to realize a fuel cell power generator excellent in durability that does not cause catalyst deterioration due to oxygen.

  Next, it becomes the starting process 1.

  In the start-up process 1, the gate valve 3035 is opened, the raw material gas is flowed to the fuel generator 3034, and processing is performed so that the concentration of the substance that contains hydrogen and is not fuel, such as carbon monoxide, is below a certain level. 3047 was closed, the pump 3049 was stopped, the gate valve 3037 and the gate valve 3043 on the anode side were opened, and the raw material gas was supplied to the fuel cell stack 3036.

  The fuel cell stack 3036 may operate the pump 3046 to circulate water having a temperature higher than that of the fuel cell stack 3036 to increase the temperature.

  Next, the startup process 2 is entered.

  In the starting process 2, the blower 3039 was operated, the gate valve 3041 and the gate valve 3042 on the cathode side were opened, and air was sent into the fuel cell stack 3036.

  Next, the fuel and current are controlled, and after the conditions for the steady operation process are reached, the operation is performed as a steady operation process.

  In the present embodiment, an example in which the source gas is reinjected once has been shown. However, the present invention is not limited to this, and the same effect can be obtained even if the same operation is performed several times when the oxygen concentration detector detects a predetermined concentration. Obtained.

  Thus, by stopping the fuel electrode and oxidant electrode of the fuel cell power generation apparatus with an inert gas and sealing, the catalyst is prevented from being deteriorated by oxygen, and the oxygen concentration at both electrodes is measured during storage. Is detected again, the deterioration of the catalyst is suppressed by reinjecting the inert gas again, and a fuel cell power generator excellent in durability that does not cause the catalyst deterioration even during long-term storage can be realized.

  Here, by using the raw material gas cleaned in the gas cleaning section as an inert gas for the fuel cell, deterioration due to start-stop and storage can be reduced easily.

  In the present embodiment described above, the detection of the oxidant gas flow path oxygen concentration in the portion between the gate valve 3041 and the gate valve 3042, and (b) the portion between the gate valve 3037 and the gate valve 3043. Both the detection of the oxygen concentration in the fuel gas flow path was performed. However, the present invention is not limited to this, and detection of the oxidant gas flow path oxygen concentration in the portion between the gate valve 3041 and the gate valve 3042, or (b) the fuel gas flow in the portion between the gate valve 3037 and the gate valve 3043. One of the detection of the road oxygen concentration may be performed.

  Further, in the present embodiment described above, (a) injection of a predetermined purge gas into the portion between the gate valve 3041 and the gate valve 3042, and (b) between the gate valve 3037 and the gate valve 3043. Both injections of a predetermined purge gas to the part were performed. However, the present invention is not limited to this, and (a) a predetermined purge gas is injected into a portion between the gate valve 3041 and the gate valve 3042, or (b) a predetermined portion is applied to the portion between the gate valve 3037 and the gate valve 3043. One of the purge gas injections may be performed.

  Note that such predetermined purge gas injection is performed in the above-described embodiment in which both the detected oxidant gas flow path oxygen concentration and the detected fuel gas flow path oxygen concentration are equal to or greater than a predetermined value. Was done in some cases. However, the present invention is not limited to this, and such predetermined purge gas injection is performed when one of the detected oxidant gas flow path oxygen concentration or the detected fuel gas flow path oxygen concentration is equal to or higher than a predetermined value. It may be broken.

(Embodiment 11)
First, the configuration of the fuel cell power generator according to the present embodiment will be described with reference mainly to FIG.

  FIG. 33 is a diagram showing a fuel cell power generator according to Embodiment 11 of the present invention.

  The fuel cell power generation device according to the present embodiment is basically the same as the fuel cell power generation device according to the tenth embodiment shown in FIG. 32, except that the anode and cathode of the fuel cell stack 3036 are used instead of the oxygen concentration detector. This is a fuel cell power generator in which a voltage detector 3052 for observing a change in potential of the fuel cell is disposed. In short, the principle of the present embodiment is that the potential increase due to the adsorption potential caused by the adsorption of oxygen to the electrode is observed.

  In the present embodiment, MEA 305 (see FIG. 30) is created as follows.

  Carbon powder acetylene black (Denka Black manufactured by Denki Kagaku Kogyo Co., Ltd., particle size 35 nm) was mixed with an aqueous dispersion of polytetrafluoroethylene (PTFE) (D1 manufactured by Daikin Industries, Ltd.) and dried. A water repellent ink containing 20% by weight of PTFE was prepared.

  This ink is applied and impregnated on carbon paper (TGPH060H manufactured by Toray Industries, Inc.) serving as a base material for the gas diffusion layer, heat treated at 300 ° C. using a hot air dryer, and the gas diffusion layer (about 200 μm). ) Was formed.

On the other hand, 66 parts by weight of a catalyst body (50 wt% Pt) obtained by supporting a Pt catalyst on Ketjen Black (Ketjen Black EC, Ketjen Black International Co., Ltd., particle size 30 nm), which is carbon powder. Is mixed with 33 parts by weight (polymer dry weight) of perfluorocarbon sulfonic acid ionomer (5% by weight Nafion dispersion manufactured by Aldrich, USA) which is a hydrogen ion conductive material and a binder, and the resulting mixture is molded. Thus, a catalyst layer (10 to 20 μm) was formed.

  The gas diffusion layer and the catalyst layer obtained as described above were joined to both surfaces of a polymer electrolyte membrane (Nafion 112 membrane manufactured by DuPont, USA) to produce MEA305.

  Next, a rubber gasket plate was joined to the outer peripheral portion of the membrane 301 of the MEA 305 produced as described above, and manifold holes for circulating cooling water, fuel gas, and oxidant gas were formed.

  On the other hand, conductive separators 307a and 307c made of a graphite plate impregnated with a phenolic resin having an outer dimension of 20 cm × 32 cm × 1.3 mm and a gas channel and a cooling water channel having a depth of 0.5 mm. Was used.

  The controller 3045 corresponds to means including the first purge gas injection means and the second purge gas injection means of the present invention, and the voltage detector 52 corresponds to the potential difference detection means of the present invention. The fuel cell power generator of the form corresponds to the fuel cell operating device of the present invention.

  The gas cleaning unit 3032 corresponds to the fuel gas cleaning means of the present invention.

  Next, the operation of the fuel cell power generator of this embodiment will be described.

  Basic operations other than the storage step 2 of the fuel cell stack 3036 are the same as those in the tenth embodiment.

  In the storage step 2 of the eleventh embodiment, after the storage step 1, the gate valve 3041 and the gate valve 3042 on the cathode side are temporarily opened, and the source gas is injected only into the cathode.

  At this time, the potential difference between the anode and the cathode of the voltage detector 3052 is 10 mV relative to the value before the raw material gas is temporarily injected (corresponding to the above-mentioned 10 ppm, which roughly corresponds to the lower limit value of the oxygen concentration that can be detected by a normal measuring method). When the above change is detected, the gate valve 3037 and the gate valve 3043 on the anode side are opened by a signal from the control unit 3045. Then, the gate valve 3041 and the gate valve 3042 on the cathode side are opened, the pump 3049 is operated, the raw material gas is reinjected into the fuel cell stack 3036 again, and the gate valve 3037 and gate valve 3043 on the anode side are moved to the cathode side. Some gate valve 3041 and gate valve 3042 were closed and sealed.

  FIG. 35 shows the change in the stack voltage and the change in the potential of the anode different from the cathode into which the source gas was injected.

  In the present embodiment, the temporary raw material gas injection is performed on the cathode side. However, the present invention is not limited to this, and similar results were obtained even when the temporary injection operation was performed on the anode side.

  It should be noted that the source gas is first injected into only one of the cathode and the anode in this way because oxygen penetrates from the sealing portion of the fuel cell stack 3036 to the entire fuel cell stack 3036, so that the potentials at both electrodes are almost equal. This is because it often changes.

  In this way, during inactive storage, inert gas is temporarily purged to one of the fuel electrode or oxidant electrode, changes in the potential difference between both electrodes are detected, and inert gas is reinjected again to suppress catalyst deterioration. In addition, it is possible to realize a fuel cell power generator excellent in durability that does not cause catalyst deterioration even during long-term storage.

  In short, a gate valve is installed upstream and downstream of the oxidant electrode and fuel electrode in the oxidant gas and fuel gas supply passages, a voltage detection device for detecting the potential difference between the oxidant electrode and the fuel electrode is arranged, and inert gas is collected. When the potential difference between the two electrodes at the time of additional purge shows a predetermined value or more, the gate valve disposed upstream and downstream of both electrodes is opened and closed, and the inert gas is reinjected again.

  More specifically, the voltage detector activates the gate valve and reinjects the inert gas, and the change in potential difference between the two electrodes is set to 10 mV or more so that the catalyst does not deteriorate due to intrusion gas from the outside or trace gas leak. An excellent fuel cell power generator can be realized.

(Comparative example)
The comparative example is similar to the tenth embodiment and the eleventh embodiment. However, the oxygen concentration detector and the voltage detector are not provided, and the re-injection of the raw material gas in the storage process 2 detects a predetermined potential difference. This is a start / stop and storage method that is performed only when

  FIG. 36 shows the voltage change of the stack and the potential change of the anode of the comparative example.

  From the change in the stack voltage shown in FIG. 34, even if oxygen has entered the fuel cell stack 36 during the storage process, no change is seen in the voltage of the fuel cell stack 3036 (as described above, oxygen is the fuel In order to penetrate the entire battery stack 3036, the potentials of both electrodes change substantially equally, and the voltage of the fuel cell stack 36, which is the difference between these potentials, does not change). Therefore, by providing the outer casing 3031 with oxygen concentration detectors 3050 and 3051, the influence of oxygen in the fuel cell stack 36 can be observed.

  That is, by performing the operation of the tenth embodiment, it is possible to prevent catalyst deterioration, and it is possible to provide a fuel cell power generator that is excellent in durability even when the start / stop operation is performed.

  From the change in the stack voltage shown in FIG. 35, a change is observed in the potential difference between the two electrodes by temporarily injecting the source gas into the cathode or anode. This is considered to be a potential change caused by oxygen entering from the outside.

  In many cases, even if the potential difference between the two electrodes is zero, the potential itself is increasing (for the above-described reason, even if oxygen has entered the fuel cell stack 3036, zero potential difference is observed between the two electrodes). When the anode is affected by the potential increase, Ru elution occurs. In the eleventh embodiment, this change in potential can be observed with a voltage detector using the change in potential of each cell when the source gas is temporarily flowed to one electrode side.

  That is, by performing the operation of the eleventh embodiment, it is possible to prevent not only catalyst deterioration due to oxygen but also catalyst deterioration due to potential rise, and provide a fuel cell power generator excellent in durability even when starting and stopping operation is performed. be able to.

  FIG. 37 shows the results of durability of the stacks subjected to the start / stop method of the tenth embodiment, the eleventh embodiment and the comparative example.

  As shown in FIG. 37, the tenth embodiment and the eleventh embodiment in which the source gas is reinjected in the storage process have a very low value of the durability deterioration rate at the number of start / stop times of 10,000 as compared with the comparative example. Can be maintained.

  As described above, this indicates that catalyst deterioration due to oxygen and catalyst deterioration due to potential increase could be prevented by reinjecting the raw material gas when storage was stopped.

  According to the present embodiment, it is possible to provide a fuel cell power generator capable of exhibiting high durability performance without causing catalyst deterioration even when the fuel cell power generator is stopped and stored for a long period of time.

Further, the above tenth and eleventh embodiments may correspond to the following embodiments of the invention. That is, as a first invention, during the storage period of the fuel cell, (1) the oxidant electrode in the oxidant gas flow path for supplying and discharging a predetermined oxidant gas to the oxidant electrode of the fuel cell An oxidant gas in a portion between an oxidant gas flow path upstream valve provided upstream and an oxidant gas flow path downstream valve provided downstream of the oxidant electrode in the oxidant gas flow path Detection of flow path oxygen concentration and / or (2) fuel gas flow provided upstream of the fuel electrode in the fuel gas flow path for supplying and discharging a predetermined fuel gas to the fuel electrode of the fuel cell Oxygen concentration detecting means for detecting the oxygen concentration of the fuel gas channel in a portion between the upstream valve of the channel and the fuel gas channel downstream valve provided downstream of the fuel electrode in the fuel gas supply channel) ,
When the detected oxidant gas flow path oxygen concentration and / or the detected fuel gas flow path oxygen concentration is equal to or greater than a predetermined value, (a) the oxidant gas flow path upstream valve and the oxidant gas flow Injection of a predetermined purge gas into a portion between the downstream valve and / or (b) a predetermined purge gas into the portion between the fuel gas flow path upstream valve and the fuel gas flow path downstream valve It is good also as a fuel cell operating device provided with the gas injection means for purge which performs injection.

Further, as a second invention, further comprising a fuel gas cleaning means for cleaning the predetermined fuel gas,
The predetermined purge gas may be the fuel cell operating device according to the first aspect of the invention, which is the purified fuel gas.

  As a third invention, the predetermined value may be 10 ppm as the fuel cell operating device of the first invention.

As a fourth invention, during the storage period of the fuel cell, (1) the oxidant electrode in an oxidant gas flow path for supplying and discharging a predetermined oxidant gas to the oxidant electrode of the fuel cell. An oxidant gas in a portion between an oxidant gas flow path upstream valve provided upstream and an oxidant gas flow path downstream valve provided downstream of the oxidant electrode in the oxidant gas flow path Detection of flow path oxygen concentration and / or (2) fuel gas flow provided upstream of the fuel electrode in the fuel gas flow path for supplying and discharging a predetermined fuel gas to the fuel electrode of the fuel cell An oxygen concentration detection step of detecting a fuel gas flow path oxygen concentration in a portion between a road upstream valve and a fuel gas flow path downstream valve provided downstream of the fuel electrode in the fuel gas supply flow path;
When the detected oxidant gas flow path oxygen concentration and / or the detected fuel gas flow path oxygen concentration is equal to or greater than a predetermined value, (a) the oxidant gas flow path upstream valve and the oxidant gas flow Injection of a predetermined purge gas into a portion between the downstream valve and / or (b) a predetermined purge gas into the portion between the fuel gas flow path upstream valve and the fuel gas flow path downstream valve It is good also as a fuel cell operating method provided with the gas injection step for purge which performs injection.

  Further, as a fifth invention, when the detected oxidant gas flow path oxygen concentration and / or the detected fuel gas flow path oxygen concentration of the fuel cell operating method of the fourth invention is greater than or equal to a predetermined value. (A) injection of a predetermined purge gas into a portion between the oxidant gas flow path upstream valve and the oxidant gas flow path downstream valve, and / or (b) the fuel gas flow path upstream valve It is good also as a program for making a computer perform the purge gas injection | pouring step which inject | pours the predetermined purge gas with respect to the part between the said fuel gas flow path downstream valves.

As a sixth invention, during the storage period of the fuel cell, (1) the oxidant electrode in the oxidant gas flow path for supplying and discharging a predetermined oxidant gas to the oxidant electrode of the fuel cell. A predetermined purge for a portion between an oxidant gas flow path upstream valve provided upstream and an oxidant gas flow path downstream valve provided downstream of the oxidant electrode in the oxidant gas flow path Or (2) a fuel gas flow path upstream valve provided upstream of the fuel electrode in the fuel gas flow path for supplying and discharging a predetermined fuel gas to and from the fuel electrode of the fuel cell; A first purge gas injection means for injecting a predetermined purge gas into a portion between the fuel gas supply flow path and a fuel gas flow path downstream valve provided downstream of the fuel electrode;
A potential difference detecting means for detecting a potential difference between the potential of the oxidant electrode and the potential of the fuel electrode;
Injection of a predetermined purge gas into a portion between the oxidant gas flow path upstream valve and the oxidant gas flow path downstream valve, or between the fuel gas flow path upstream valve and the fuel gas flow path downstream valve When the change in the detected potential difference before and after the injection of the predetermined purge gas to the portion is greater than or equal to a predetermined value, (a) the oxidant gas flow path upstream valve and the oxidant gas flow Injection of a predetermined purge gas into the portion between the downstream valve and (b) injection of a predetermined purge gas into the portion between the fuel gas flow path upstream valve and the fuel gas flow path downstream valve. It is good also as a fuel cell operating device provided with the gas injection means for the 2nd purge performed again.

In addition, as a seventh invention, further comprising a fuel gas cleaning means for cleaning the predetermined fuel gas,
The predetermined purge gas may be the fuel cell operating device according to the sixth aspect of the invention, which is the purified fuel gas.

  As an eighth invention, the predetermined value may be 10 mV, which is the fuel cell operating device of the sixth invention.

As a ninth aspect of the invention, during the storage period of the fuel cell, (1) the oxidant electrode in an oxidant gas flow path for supplying and discharging a predetermined oxidant gas to the oxidant electrode of the fuel cell. A predetermined purge for a portion between an oxidant gas flow path upstream valve provided upstream and an oxidant gas flow path downstream valve provided downstream of the oxidant electrode in the oxidant gas flow path Or (2) a fuel gas flow path upstream valve provided upstream of the fuel electrode in the fuel gas flow path for supplying and discharging a predetermined fuel gas to and from the fuel electrode of the fuel cell; A first purge gas injection step for injecting a predetermined purge gas into a portion between the fuel gas supply flow path and a fuel gas flow path downstream valve provided downstream of the fuel electrode;
A potential difference detection step for detecting a potential difference between the potential of the oxidant electrode and the potential of the fuel electrode;
Injection of a predetermined purge gas into a portion between the oxidant gas flow path upstream valve and the oxidant gas flow path downstream valve, or between the fuel gas flow path upstream valve and the fuel gas flow path downstream valve When the change in the detected potential difference before and after the injection of the predetermined purge gas to the portion is greater than or equal to a predetermined value, (a) the oxidant gas flow path upstream valve and the oxidant gas flow Injection of a predetermined purge gas into the portion between the downstream valve and (b) injection of a predetermined purge gas into the portion between the fuel gas flow path upstream valve and the fuel gas flow path downstream valve. It is good also as a fuel cell operating method provided with the 2nd purge gas injection | pouring step performed again.

  According to a tenth aspect of the present invention, in the fuel cell operating method of the ninth aspect, during the storage period of the fuel cell, (1) To supply and discharge a predetermined oxidant gas to the oxidant electrode of the fuel cell An oxidant gas flow path upstream valve provided upstream of the oxidant electrode in the oxidant gas flow path, and an oxidant gas flow path provided downstream of the oxidant electrode in the oxidant gas flow path. Injection of a predetermined purge gas into the portion between the downstream valve or (2) upstream of the fuel electrode in the fuel gas flow path for supplying and discharging a predetermined fuel gas to the fuel electrode of the fuel cell A predetermined purge gas is injected into a portion between the fuel gas flow path upstream valve provided in the fuel gas flow path and the fuel gas flow path downstream valve provided downstream of the fuel electrode in the fuel gas supply flow path First purge gas inlet And injection of a predetermined purge gas into a portion between the oxidant gas flow path upstream valve and the oxidant gas flow path downstream valve, or the fuel gas flow path upstream valve and the fuel gas flow path downstream When the change in the detected potential difference before and after the injection of the predetermined purge gas to the portion between the valve and the valve is greater than or equal to a predetermined value, (a) the oxidant gas flow path upstream valve and the Injection of a predetermined purge gas into a portion between the oxidant gas flow path downstream valve and (b) a predetermined purge with respect to a portion between the fuel gas flow path upstream valve and the fuel gas flow path downstream valve It is good also as a program for making a computer perform the 2nd gas injection step for purging which injects gas again.

  The eleventh invention may be a recording medium carrying the program of the fifth or tenth invention, which can be processed by a computer.

  The program according to the present invention is a program for causing a computer to execute the functions of all or part of the above-described fuel cell system of the present invention (or apparatus, element, circuit, unit, etc.). It may be a program that operates in cooperation with a computer.

  The present invention is a medium carrying a program for causing a computer to execute all or part of the functions of all or part of the above-described fuel cell power generation system of the present invention, and is readable by a computer; The read program may be a medium that executes the function in cooperation with the computer.

  The “part of means (or apparatus, element, circuit, part, etc.)” of the present invention and the “part of step (or process, operation, action, etc.)” of the present invention are those It means several means or steps among a plurality of means or steps, or means some function or part of operation within one means or step.

  In addition, some devices (or elements, circuits, parts, and the like) of the present invention mean some devices among the plurality of devices, or some devices within one device. Means (or an element, a circuit, a part, etc.), or a part of the functions of one means.

  Further, the present invention includes a computer-readable recording medium that records the program of the present invention.

  Further, one usage form of the program of the present invention may be an aspect in which the program is recorded on a computer-readable recording medium and operates in cooperation with the computer.

  Further, one usage form of the program of the present invention may be an aspect in which the program is transmitted through a transmission medium, read by a computer, and operated in cooperation with the computer.

  The data structure of the present invention includes a database, data format, data table, data list, data type, and the like.

  The recording medium includes a ROM and the like, and the transmission medium includes a transmission mechanism such as the Internet, light, radio waves, sound waves, and the like.

  The computer of the present invention described above is not limited to pure hardware such as a CPU, and may include firmware, an OS, and peripheral devices.

  As described above, the configuration of the present invention may be realized by software or hardware.

  The fuel cell system according to the present invention can appropriately cope with problems such as acceleration of drying of the electrolyte membrane and local reaction, and can stabilize the performance of the fuel cell even if the fuel cell is stopped and generated repeatedly. It is useful as a power source, a power source for portable devices, a power source for electric vehicles, and a household fuel cell system.

The structure of a part of the unit cell of the polymer electrolyte fuel cell in Embodiments 1 to 3 of the present invention and the conventional example is shown. The structure of the stack which laminated | stacked the polymer electrolyte fuel cell in Embodiment 1-3 of this invention and a prior art example is shown. It is a block diagram which shows the polymer electrolyte fuel cell system in Embodiment 1-3 of this invention. It is a figure which shows the flowchart for demonstrating operation | movement of the polymer electrolyte fuel cell system in Embodiment 1 of this invention. It is a figure which shows the flowchart for demonstrating operation | movement of the polymer electrolyte fuel cell system in Embodiment 2 of this invention. It is a figure which shows the flowchart for demonstrating operation | movement of the polymer electrolyte fuel cell system in Embodiment 3 of this invention. It is a figure which shows the flowchart for demonstrating the detail of the stop process 1 of the polymer electrolyte fuel cell system in Embodiment 1 of this invention. It is a block diagram which shows the fuel cell system in Embodiment 4 of this invention. It is a block diagram which shows the fuel cell system in Embodiment 5 of this invention. 1 is a cross-sectional view of a solid polymer electrolyte fuel cell equipped with an electrolyte assembly (MEA). It is the block diagram which showed the basic composition of the fuel cell power generation device. It is the block diagram which showed the structure of the fuel cell power generation apparatus which concerns on Embodiment 6 of this invention. It is a figure of the first half part of the flowchart explaining the gas supply operation | movement which concerns on Embodiment 6 of this invention. It is a figure of the second half part of the flowchart explaining the gas supply operation | movement which concerns on Embodiment 6 of this invention. It is the alternating current impedance profile figure of the fuel cell measured by varying the applied frequency with respect to the fuel cell in the range of 0.1 Hz to 1 kHz. It is a figure which shows the relationship between the relative humidity of an electrolyte membrane, and electrical conductivity. It is the block diagram which showed the structure of the fuel cell power generation apparatus which concerns on Embodiment 7 of this invention. It is a figure of the first half part of the flowchart explaining the gas supply operation | movement which concerns on Embodiment 7 of this invention. It is a figure of the second half part of the flowchart explaining the gas supply operation | movement which concerns on Embodiment 7 of this invention. It is the block diagram which showed the structure of the fuel cell power generation apparatus which concerns on Embodiment 8 of this invention. It is a figure of the first half part of the flowchart explaining the gas supply operation | movement which concerns on Embodiment 8 of this invention. It is a figure of the second half part of the flowchart explaining the gas supply operation | movement which concerns on Embodiment 8 of this invention. It is a figure of the characteristic evaluation result of MEA voltage based on the number of times of starting and stopping. It is a figure which shows the structure of the fuel cell system of Embodiment 9 of this invention. It is a figure which shows transition of the average value of the internal resistance of the single cell in the operating method of the fuel cell system of Embodiment 9 of this invention. It is a figure which shows transition of the battery temperature in the operating method of the fuel cell system of Embodiment 9 of this invention. It is a figure which shows transition of the electric power generation amount in the operating method of the fuel cell system of Embodiment 9 of this invention. It is a figure which shows transition of the average value of the voltage of the single cell in the operating method of the fuel cell system of Embodiment 9 of this invention. It is a schematic longitudinal cross-sectional view which shows a part of fuel cell stack in the fuel cell system of Embodiment 9 of this invention. It is a schematic sectional drawing for demonstrating the structure of a part of unit cell of the polymer electrolyte fuel cell in Embodiment 10 of this invention. It is the schematic for demonstrating the structure of the stack which laminated | stacked the polymer electrolyte fuel cell in Embodiment 10 of this invention. It is the schematic of the fuel cell power generator in Embodiment 10 of this invention. It is the schematic of the fuel cell power generator in Embodiment 11 of this invention. It is explanatory drawing which showed the relationship between the voltage change and oxygen concentration in the start-stop operation of the fuel cell power generation device in Embodiment 10 of this invention. It is explanatory drawing which showed the relationship between the voltage change in the starting stop operation of the fuel cell power generation device in Embodiment 11 of this invention, and the electric potential change between both poles of an anode and a cathode. It is explanatory drawing which showed the voltage change in the start-stop operation of the fuel cell power generator in the comparative example of this invention. It is explanatory drawing which showed the relationship between the frequency | count of starting / stopping of the fuel cell power generator in Embodiment 10, Embodiment 11, and a comparative example of this invention, and durability. It is a block diagram of the fuel cell system by a prior art.

Explanation of symbols

1 Electrolyte 2a Catalytic reaction layer (anode side)
2c Catalytic reaction layer (cathode side)
3a Diffusion layer (anode side)
3c Diffusion layer (cathode side)
4a Electrode (Anode side)
4c electrode (cathode side)
7a Separator (Anode side)
7c Separator (cathode side)
32 Cleaner 35 Fuel Generator 41 Humidifier 43 Power Circuit Unit 44 Control Unit 52 Voltage Measurement Unit 34 49, 51, 57, 58 On-off Valve 59, 60 Pressure Measurement Unit 81 Fuel Cell 82 Combustion Generator 83 Water Supply Means 84 Combustion 85 Blower 86 Purge air supply means 87 Bypass pipe 88 Flow path switching means 89 On-off valve 810 Raw material cathode supply means 811 Cathode closing means 812 Anode closing means 111 Electrolyte membrane 112a Anode catalytic reaction layer 112c Cathode catalytic reaction layer 113a Anode Gas diffusion layer 113c Gas diffusion layer of cathode 114a Anode 114c Cathode 115a MEA gasket on anode side 115c MEA gasket on cathode side 116a Conductive separator plate for anode 116c Conductivity for cathode Separator plate 117 MEA
118a Fuel gas flow path 118c Oxidant gas flow path 119a Groove formed in the conductive separator plate 116a 119c Groove formed in the conductive separator plate 116c 120 Fuel cell 121 Fuel cell 122 Raw material gas supply means 122p Gas cleaning unit 123 Fuel generator 123e Reformer 123f Transformer 123g CO removal unit 124 Humidification unit 125 Circuit unit 126 Measurement unit 127 Control unit 128 Blower 129 First switching valve 130 First cutoff valve 131 Second cutoff valve 132 Third Shut-off valve 133 Water removal unit 134 Total heat exchange humidifier 135 Hot water humidifier 141 First check valve 142 Second switching valve 143 Third switching valve 144 Fourth switching valve 145 First circulation piping 146 Second Circulating piping 147 Anode exhaust piping 148 Second check valve 1 51 Source gas branch piping 152 Fifth switching valve 153 Second connection piping 154 Sixth switching valve 155 Split valve 160 Cathode exhaust piping 161 Fuel gas supply piping 162 Oxidant gas supply piping 163 Source gas supply piping 164 First Connecting pipe 170a Anode mass flow meter 170c Cathode mass flow meter 171 Temperature detection means 172a Anode output terminal 172c Cathode output terminal 173 Impedance measuring instrument 174 First water supply means 175 Second water supply means 201 Fuel cell stack 202 Oxidation Agent gas control device 203 Fuel generator 203b Bypass 204 Voltage detection device 205 Control unit 206 Power circuit unit 2071 to 79 Solenoid valve 208 Gas cleaning unit 209 Total heat exchange type humidifier 2010 Hot water type humidifier 2011 High Wave resistance meter 2012 Fuel gas supply pipe 2012a Connecting pipe 2013 Oxidant gas supply pipe 2021 Hydrogen ion conductive polymer electrolyte membrane 2022a, 22b Catalyst layer 2023a, 23b Gas diffusion layer 2024a Anode 2024b Cathode 2025 Gasket 2026a Anode side separator plate 2026b Cathode Side separator plate 2027 Membrane / electrode assembly 2028a, 28b Gas flow channel 2029 Cooling water flow channel 2030 Sealing portion 301 Electrolyte membrane 302a, 302c Catalytic reaction layer 303a, 303c Diffusion layer 307a, 307c Separator 3021 Current collector plate 3022 Insulating plate 3031 Outer casing Body 3032 Cleaning unit 3034 Fuel generator 3036 Fuel cell stack 3040 Humidifier 3044 Power circuit unit 3045 Control unit 3050, 3051 Oxygen concentration Detector 3052 voltage detector

Claims (10)

A fuel cell that generates power from fuel gas and oxidant gas;
Fuel gas supply means for supplying the fuel gas to the anode side of the fuel cell;
Oxidant gas supply means for supplying the oxidant gas to the cathode side of the fuel cell;
A raw material gas supply means for supplying the raw material gas of the fuel gas to the fuel cell;
Control means for controlling the fuel gas supply means, the oxidant gas supply means and the source gas supply means,
By the control of the control means,
When starting power generation of the fuel cell,
Before the oxidant gas supply means and the fuel gas supply means supply the fuel gas and the oxidant gas to the fuel cell, the source gas supply means uses the source gas at least on the cathode side of the fuel cell. A fuel cell system to be purged.   The fuel cell system according to claim 1, wherein the source gas supply means purges the anode side after purging the cathode side in the fuel cell. A fuel gas pipe provided between the fuel gas supply means and the cathode side of the fuel cell;
A fuel gas on-off valve provided in the middle of the fuel gas pipe;
An oxidant gas pipe provided between the oxidant gas supply means and the anode side of the fuel cell;
An oxidant gas on-off valve provided in the middle of the oxidant gas pipe;
A source gas pipe connected to a part of the oxidant gas pipe between the source gas supply means, the oxidant gas on-off valve and the cathode side of the fuel cell;
A source gas on-off valve provided in the middle of the source gas pipe,
The fuel cell system according to claim 1 or 2. A cathode side discharge pipe for discharging off-gas discharged from the cathode side of the fuel cell;
A cathode-side off-gas on-off valve provided in the middle of the cathode-side exhaust pipe;
The purge,
Open the cathode side off-gas on-off valve,
The fuel cell system according to claim 3, wherein the raw material gas on-off valve is opened after being opened for a predetermined period and then closed. An additional source gas pipe connected to a part of the source gas pipe between the source gas supply means and between the fuel gas on-off valve and the anode side of the fuel cell;
An additional raw material gas on-off valve provided in the middle of the additional raw material gas pipe;
An anode side discharge pipe for discharging off-gas discharged from the anode side of the fuel cell;
An anode-side off-gas on-off valve provided in the middle of the anode-side exhaust pipe,
The purge,
After opening the source gas on-off valve,
Furthermore, open the anode side off-gas on-off valve,
5. The fuel cell system according to claim 4, wherein the additional source gas on-off valve is opened for a predetermined period. The operation in which the oxidant gas supply means and the fuel gas supply means supply the fuel gas and the oxidant gas to the fuel cell,
After opening the anode-side off-gas on-off valve, open the fuel gas on-off valve,
The fuel cell system according to claim 5, which is performed by opening the cathode-side off-gas on-off valve and then opening the oxidant gas on-off valve. A fuel cell for generating electric power from a fuel gas and an oxidant gas, an oxidant gas supply means for supplying an oxidant gas to the fuel cell, and a fuel supply means for supplying the fuel gas to the fuel cell A method for starting a fuel cell system, comprising:
When starting power generation of the fuel cell,
Prior to supplying the fuel gas and the oxidant gas to the fuel cell, at least a cathode side of the fuel cell is purged with a raw material gas used to generate the fuel gas, and a method for starting a fuel cell power generation system .   The start method of the fuel cell system according to claim 7, wherein the anode side is purged after purging the cathode side in the fuel cell.   8. The fuel cell system start-up method according to claim 7, wherein at least the cathode of the fuel cell is supplied before the fuel gas and the oxidant gas are supplied to the fuel cell when power generation of the fuel cell is started. A program for controlling, by a computer, a step of purging the side with a raw material gas used to generate the fuel gas.   A recording medium carrying the program according to claim 9, which can be processed by a computer.

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