JPH11176459A - Water supply device for fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water supply device for a fuel cell to achieve continuous and stable power generation by supply of water to a fuel cell main body. SOLUTION: A water supply device for a fuel cell to circulate water for supplying it with fuel to passage to supply fuel to a fuel cell main body 5 is provided with a waster circulation passage, a water pump 3 disposed in the water circulation passage, and a water pump 7 arranged within the water circulation passage and disposed above the fuel cell main body 5, a connection conduit to connect the fuel cell main body 5 to the water sump 7 is extended from a bottom part of the fuel cell main body 5 vertically downward for a specified distance H2, and then extended vertically upward from the bottom part of the fuel cell main body 5 for a specified distance, and relations of expressions H1+H2>P, P>H1 is established among H1, H2, P when pressure (water column height) of fuel in an anode electrode is P.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water supply device for a fuel cell.

[0002]

2. Description of the Related Art Conventionally, a fuel cell, a storage battery, a fuel supply source, a controller, and the like are provided, and surplus power after supplying power generated by the fuel cell to an external load is stored in the storage battery. Fuel cells that supply power to an external load by supplementing power from a storage battery when battery power is insufficient are known, and many expectations are being raised as a power source for civil engineering and construction work, a home emergency power source, and the like.

[0003] There are two types of fuel cells: acidic fuel cells and alkaline fuel cells. The characteristics of a polymer electrolyte fuel cell, one of the acidic fuel cells, will be described below. As shown in FIG. 3, the polymer electrolyte fuel cell uses a polymer ion exchange membrane (for example, a fluororesin type ion exchange membrane having a sulfonic acid group) for the electrolyte 01, and a catalyst electrode (for example, platinum) on both sides thereof. Etc.) and an electrode assembly 06 including current collectors 02 and 03 and current collectors 04 and 05.

[0004] Hydrogen in the humidified fuel supplied to the anode electrode is hydrogen-ionized on the catalyst electrode (anode electrode) 02, and the hydrogen ions pass through the electrolyte 01 with H ^+. _{As 2} O, it moves together with water to the cathode electrode side. The transferred hydrogen ions react with oxygen in the oxidant (for example, air) on the catalyst electrode (cathode electrode) 03 and the electrons flowing through the external circuit 07 to generate water. The generated water is transported from the cathodes 03 and 05 to the remaining oxidant and discharged out of the fuel cell. At this time, the flow of electrons flowing through the external circuit 07 can be used as DC electric energy.

In order to realize the above-mentioned hydrogen ion permeability in the polymer ion exchange membrane serving as the electrolyte 01, it is necessary to keep the polymer ion exchange membrane in a sufficiently water-retaining state at all times. Yes, for example, the fuel or oxidant is made to contain saturated water vapor corresponding to the vicinity of the operating temperature of the fuel cell (normal temperature to about 100 ° C.), that is, humidified to supply the fuel and the oxidant to the electrode assembly 06 to retain the water of the membrane. I try to keep my condition. In addition, the fuel cell generates heat during operation and needs to be cooled.

On the other hand, in the case of an alkaline fuel cell, hydroxyl ions move in the electrolyte and react with fuel gas (hydrogen gas) on the anode electrode to generate water. The generated water is transported from the anode to the remaining fuel gas and discharged out of the fuel cell.

[0007]

As described above, the fuel cell main body supplies water to the polymer ion exchange membrane and other electrolytes of the fuel cell main body and cools the fuel cell in order to continuously and stably generate power. Or need to. The present inventors first,
A water supply system for fuel cells was proposed (Japanese Patent Application No. 9-271).
351), there is still room for improvement. An object of the present invention is to provide a water replenishing device for a fuel cell capable of continuously and stably generating power by supplying water to the fuel cell body.

[0008]

According to a first aspect of the present invention, there is provided a fuel cell system comprising: circulating water together with a fuel or an oxidant in at least one of flow paths for supplying a fuel or an oxidant to a fuel cell body. What is claimed is: 1. A water supply device for a fuel cell, comprising: a water circulation path; a water pump disposed in the water circulation path; and a water pump disposed in the water circulation path and disposed above the fuel cell body. A connection pipe connecting the fuel cell body and the water reservoir extends vertically below the fuel cell body bottom by a predetermined distance H2 and then extends vertically above the fuel cell body bottom by a predetermined distance It has a structure extending by H1, and when the value of the pressure of the fuel or oxidant flowing simultaneously with water expressed by the height of the water column is represented by P, the following equation (1) and the equation (2) Relationship It is characterized in that the hold. Formula (1): H1 + H2> P Formula (2): P> H1

The fuel cell receives a fuel gas cylinder, a fuel gas such as hydrogen gas and methane gas, and an oxidant such as air, and generates power to generate high-temperature exhaust oxidant and exhaust fuel gas. A power supply unit including a power converter such as a DC / AC inverter for converting DC power generated by the fuel cell into AC, a water replenishing device of the present invention for replenishing the fuel cell body with water, and controlling these components And a control device for performing the operation. The water in the water circulation path in which the water reservoir of the water supply device of the present invention is installed is supplied to the fuel cell body together with the fuel or the oxidant to at least one of the flow paths for supplying the fuel or the oxidant. The water reservoir is disposed in the water circulation path and at a specific position above the fuel cell main body and satisfying both the expressions (1) and (2). When the above equation (1) is satisfied, the fuel or oxidant does not enter the water circuit during operation. When the above equation (2) is satisfied, water in the water reservoir enters the fuel cell body during operation. Since troubles such as inability to generate power due to the stoppage of supply of fuel or oxidant due to water immersion do not occur, power generation can be performed continuously and stably. It is preferable that the gas phase part of the water reservoir is open to the atmosphere.

According to a second aspect of the present invention, in the water supply device for a fuel cell according to the first aspect, water is circulated and supplied together with the fuel to a flow path for supplying the fuel to the fuel cell body, and the fuel is supplied. An opening / closing valve that is closed when fuel supply is stopped is provided on at least one of a connecting pipe connecting the battery body and the water reservoir and a connecting pipe connecting the water reservoir and the water pump. I do. If the on-off valve is closed when supply of fuel to the fuel cell main body is stopped, water in the water reservoir can be prevented from entering the fuel cell main body.

According to a third aspect of the present invention, in the water supply device for a fuel cell according to the first or second aspect, a throttle valve is provided in an exhaust pipe for exhausting exhaust fuel. It is. From the viewpoint of extending the life of the fuel cell body, it is preferable to provide a throttle valve in the exhaust pipe of the exhaust fuel and exhaust the exhaust fuel containing impurities accumulated in the exhaust pipe to the outside through the throttle valve.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is an explanatory side view of one embodiment of a water supply device for a fuel cell according to the present invention, and FIG. 2 is an explanatory diagram illustrating a water supply device for a fuel cell according to the present invention. In FIG. 1, a fuel cell 1 includes a fuel gas cylinder 3 in a case 2.
Is stored in an upright state. A control unit 4 including a secondary battery (not shown) and a DC / DC converter and the like are stored in the upper part of the rear part of the case 2, and hydrogen as fuel and air as an oxidant are supplied to the middle part to perform electrochemical control. A fuel cell main body 5 that generates power by reacting is accommodated, and a DC / AC inverter 6 and a water reservoir 7 are accommodated in a lower stage.

The hydrogen gas supplied from the fuel gas cylinder 3 to the anode of the fuel cell main body 5 via the regulator and the solenoid valve is taken into the case 2 from the outside via the reaction air inlet 9 by the fan 8 and is taken into the fuel cell main body 5. The electrochemical reaction is performed in the fuel cell main body 5 with the air sent to the cathode of the fuel cell 5 to generate electricity, and a small amount of unreacted exhaust hydrogen and exhaust air are exhausted to the outside of the case 2. In addition, the fuel cell 1
The fuel cell body 5 is located in the vicinity of the reaction air intake 9 of the case 2 so that the intake from the outside can be performed smoothly. Reference numeral 10 denotes an exhaust duct for discharging exhaust air from the fuel cell main body 5 to the outside of the case 2. The high-temperature exhaust air flowing as indicated by the white arrow contains moisture (including a part of the generated water and the circulating water) that is condensed on the inner surface of the exhaust duct 10 and the surface of the baffle plate to separate the moisture. Air is discharged out of the case 2. The separated water collects in a drain tank 11 connected to a lower portion by a gradient provided in the exhaust duct 10 as shown by an arrow,
Once stored, the water is drained to the outside via the drain pipe 12.

Reference numeral 13 denotes a water pump for pumping water from the water reservoir 7 and supplying it to the polymer ion exchange membrane of the fuel cell main body 5 to keep the water constantly and to cool the water. To be used.

As shown in FIG. 2, water is supplied together with hydrogen to a flow path 14 for supplying hydrogen to the fuel cell main body 5. The water supply device for the fuel cell 1 of the present invention includes a water circulation path 15, a water pump 13 disposed in the water circulation path 15, and a specific position disposed in the water circulation path 15 and above the fuel cell main body 5. Is provided with a water reservoir 7 arranged at the bottom. A connecting pipe line 16 connecting the fuel cell main body 5 and the water reservoir 7 has a predetermined distance H2 (m) vertically below the bottom L1 of the fuel cell main body 5.
m), and then extends vertically above the bottom L1 of the fuel cell body 5 by a predetermined distance H1 (mm) (from the bottom L1 of the fuel cell body 5 vertically to the liquid level in the reservoir 7). It has the following structure. When the pressure of hydrogen flowing at the same time as the water, that is, the value of the hydrogen pressure at the anode electrode represented by the height of the water column is represented by P (mm), the above equation (1) and the equation It is important that the relationship (2) be established. The pressure of hydrogen at the anode electrode is, for example, about 500 mmH ₂ O when represented by the height of a water column. In this case, the above P is about 500 mm.

Reference numeral 17 denotes an atmosphere opening pipe for opening the gas phase portion of the water reservoir 7 to the atmosphere, and reference numeral 18 denotes a throttle valve for adjusting the pressure of exhaust hydrogen accumulated in the exhaust pipe 19 to the outside and exhausting the same. When the equation (1) is satisfied as described above, hydrogen does not enter the water circulation path 16 during operation. When the equation (2) is satisfied, water in the water reservoir 7 is supplied to the fuel cell body 5 during operation. No troubles such as water immersion, stopping supply of fuel or oxidizing agent, and no longer being able to generate power are prevented.

Reference numeral 20 denotes an opening / closing valve 1 provided in a connecting pipe 16 connecting the fuel cell body 5 and the water reservoir 7, and 21 denotes an opening / closing valve provided in a connecting pipe 22 connecting the water reservoir 7 and the water pump 13. Valve 2. If the on-off valves 20 and 21 are closed when the supply of fuel to the fuel cell body 5 is stopped, water in the water reservoir 7 can be prevented from entering the fuel cell body 5.

Since the present invention is not limited to the above embodiment, various modifications can be made without departing from the spirit of the present invention.

[0019]

According to the fuel cell water replenishing device of the present invention, water can be replenished to the fuel cell main body to continuously and stably generate power. If the on-off valve is closed when supply of fuel to the fuel cell main body is stopped, water in the water reservoir can be prevented from entering the fuel cell main body. By providing a throttle valve in the exhaust pipe of the exhaust fuel and exhausting the exhaust fuel containing impurities accumulated in the exhaust pipe to the outside through the throttle valve, the life of the fuel cell body can be extended.

[Brief description of the drawings]

FIG. 1 is an explanatory side view of an embodiment of a water supply device for a fuel cell according to the present invention.

FIG. 2 is an explanatory view illustrating the water supply device for a fuel cell of the present invention shown in FIG. 1;

FIG. 3 is an explanatory diagram showing characteristics of a polymer electrolyte fuel cell.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fuel cell 2 Case 3 Fuel gas cylinder 4 Control device 5 Fuel cell main body 6 DC / AC inverter 7 Water reservoir 8 Fan 13 Water pump 14 Flow path 15 Water circulation path 16, 22 Connection pipe line 17 Open air pipe 18 Throttle valve 19 Exhaust pipe Road 20 On-off valve 1 21 On-off valve 2

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Akio Kawakami 2-5-5-Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd.

Claims (3)

[Claims] 1. A water replenishing device for a fuel cell, wherein water is circulated and supplied together with a fuel or an oxidant to at least one of flow paths for supplying a fuel or an oxidant to a fuel cell body. A water pump disposed in the water circulation path, and a water reservoir disposed in the water circulation path and disposed above the fuel cell main body, and a connecting pipe connecting the fuel cell main body and the water reservoir. The path extends vertically below the bottom of the fuel cell body by a predetermined distance H2, and then extends vertically above the bottom of the fuel cell body by a predetermined distance H2.
It has a structure extending by one and the value of the pressure of the fuel or oxidant flowing simultaneously with the water expressed by the height of the water column is P
Where H1, H2, and P satisfy the following equations (1) and (2). Formula (1): H1 + H2> P Formula (2): P> H1 2. A fuel supply system according to claim 1, wherein water is circulated and supplied to a flow path for supplying fuel to the fuel cell main body, and a connection pipe connecting the fuel cell main body and the water reservoir and the water reservoir and the water pump are provided. 2. The water supply device for a fuel cell according to claim 1, wherein an on-off valve that closes when fuel supply is stopped is provided in at least one of the connecting pipe lines to be connected. 3. The water replenishing device for a fuel cell according to claim 1, wherein a throttle valve is provided in an exhaust pipe for exhausting exhaust fuel.