JPS61158672A - Method for warming up air-cooled fuel cell - Google Patents

Abstract

PURPOSE:To enable a cell to be warmed up fast in a short time, from the temperature under a stopping condition to the assigned starting temperature, by preparing a catalyst on cooling-gas paths and introducing a flammable gas there at the starting time of the cell. CONSTITUTION:Reaction-gas-supplying paths 3 for fuel gas are formed on the upper surface of an upper split plate 2a of separator plates 2, on the other hand, reaction-gas-supplying paths 4 for air are formed under the lower surface of a lower split plate 2b, and tunnel-shaped cooling medium paths 5 are formed on the surface on which both split plates 2a and 2b make contact with each other. In order to warm up the body of a fuel cell 22 from the temperature under a stopping condition to the starting temperature, a part of reformed gas is mixed with air, which is supplied by means of a gas mixer 33, in the assigned concentration, and this mixed gas is introduced to the cooling medium paths 5, which are coated with a catalyst, in the body of the cell. Hence, since the separator plates 2 are directly heated by oxidation heat, which is generated by reaction of platinum, on the catalyst layer 9, which the flammable gas, the body of the cell can be warmed up fast.

Description

[Detailed Description of the Invention] [Technical field to which the invention pertains] The present invention relates to an air-cooled fuel cell in which a cooling gas separated from a reaction gas is supplied to a cooling gas passage isolated from an electrolyte. This invention relates to a temperature raising method for starting a battery.

[Prior art and its problems]

As an example of this type of fuel cell, for example, Japanese Patent Application Laid-Open No. 56-16836
5 (corresponding US Pat. No. 4,276,355) is known. This is achieved by installing manifolds for fuel, oxidizer, and cooling gas on opposite sides of the cell star and controlling the flow of reactant gas and cooling gas independently! This structure is designed to prevent the electrolyte from scattering due to excessive gas supply, and to reduce the pressure drop of the cooling gas to improve the circulation movement of the cooling gas.

In this regard, the applicant had previously filed a U.S. Pat.
1909, proposed a configuration in which the gas passages for the cooling gas and the stored reaction gas were formed in a U-shaped configuration, and the gas supply and discharge ports were provided on the same side of the cell stack. This #4M
, to? What is particularly noteworthy is that a cooling gas passage is provided for each separator interposed between each cell, which increases the heat exchange area with the cells and achieves more effective cooling. can be done. In particular, it is possible to improve temperature variations in the surface direction of the cell, which tend to occur in the UW gas supply system. The configuration will be explained below based on the drawings.

As shown in FIGS. 3 to 6, the unit cell 1 is made up of a matrix, a kusu tgila, an anode electrode 1b and a canard 1i1c stacked on both sides of the matrix and the kusu layer. Separate plates 2 with lips are stacked on top and bottom. Here, the rectangular separate plate 2 has two opposite sides A and B out of its four sides, and a plurality of tunnels arranged in parallel in the middle layer of the plate so as to open between the sides. Cooling medium connoisseur #! R5 is perforated, and the structure is such that air as a cooling medium is forced in from the external cooling air system and the locust system through a manifold 6 shown by a chain link (FIG. 4).

On the other hand, the anode 1 of the cell 1 is placed on both the upper and lower surfaces of the separate plate 2! A reaction gas supply path 3 for fuel gas is formed on the side facing &1b, and a reaction gas supply path 4 for air is formed on the side 1!11 facing the canned electrode IC. Here, each reaction gas supply path 3.4 is a plurality of concave grooves lined up on the surface of the separate plate 2, and the reaction gas supply and discharge ports are connected to the sides A and B where the cooling medium path 5 is opened. It is formed so as to open on the other two sides C and D that are directly opposite to each other.

Further, in the illustrated embodiment, the reactant gas supply path 3 for fuel gas has its supply and discharge ports both on the side surface of the same side C (FIG. 5).
The reactant gas supply port and the discharge port of the other air reactant gas supply path 4 are connected in a U-shape so that the supply and discharge ports of the reactant gas supply path 4 open at the same side (Fig. 6). ,
The structure is such that reactant gases such as fuel gas and air are supplied from the outside through manifolds 7.8 shown by chain lines arranged on the 1W1 side of the fuel cell in correspondence with the respective reactant gas supply paths 3 and 4.

With this configuration, during operation of the fuel cell, reactant gases such as fuel gas and air are distributed and supplied to all the cells 1 constituting the cell star of the fuel cell through the reactant gas supply paths 3 and 4, and are also supplied through the cooling medium path 5. Air as a cooling medium is evenly forced into all of the separate plates 2.

The amount of air blown to the cooling medium passage 5 is set separately from the amount of air supplied to the reaction gas, and is controlled to a flow rate that maintains the operating temperature of the battery at an appropriate temperature in response to the heat generated by the battery. Supplied. As a result, while the fuel cell performs a predetermined power generation action, the heat of reaction is removed by the air flowing through the cooling medium passage.

By the way, in order to operate the above-mentioned air-cooled fuel cell efficiently, for example, in the case of a phosphoric acid type fuel cell, the operating temperature of the cell is usually reduced to 1.
Although the battery is operated at a temperature maintained at about 90° C., when starting the battery from a stopped state, the battery must be heated to a temperature of 9, for example, 140° C. or higher, which does not adversely affect the characteristics of the battery. Up to now, two methods have been known for heating an air-cooled fuel cell having the above structure.

The first method is to use a heater part (
The hot air heated by this heater is introduced into the cooling medium passage and heated to the desired temperature. The second method is a fuel cell power generation plant consisting of a fuel cell main body and a fuel reformer, in which combustion exhaust gas from a burner for heating the reforming catalyst in the reformer is passed into the cooling medium passage of the cell main body. In this method, the sample is introduced and heated to the desired temperature. In the conventional battery heating method described above, the temperature is raised by heat exchange between a solid cooling plate and a gaseous cooling medium, but in heat exchange between a solid and a gas, the gas heat transfer straw is replaced by a liquid This is because it is extremely low compared to solids.

In order to raise the temperature of the battery to the desired temperature in a short period of time (for example, a few minutes to several minutes), a large amount of high-temperature air of several hundred degrees Celsius must be introduced into the cooling medium passage on a floor with a large output capacity. Not necessarily,
In practical use, there are restrictions on the temperature of the heated air and the capacity of the blower used, taking into consideration the heat resistance of the battery constituent materials and the efficiency of the power generation plant, so it takes a long time to raise the temperature of the battery to the desired temperature. It took a long time (2 to 3 hours).

[Purpose of the invention]

The present invention has been made in view of the above, and an object of the present invention is to provide a method for quickly raising the temperature of an air-cooled fuel cell from a stopped state to a desired starting temperature in a short time.

[Key points of the invention]

According to the present invention, in an air-cooled fuel cell in which a cooling gas separate from a reaction gas is supplied to a cooling gas passage separated from an electrolyte, a catalyst is provided in the cooling gas passage, and the This is achieved by introducing flammable gas into the cooling gas passage and directly heating the battery using the heat of oxidation caused by the reaction between the catalyst and the flammable gas.

In a fuel cell to which the present invention is applied, it is important that the cooling gas is separated from the reaction gas and that the cooling gas passage is isolated from the electrolyte. In other words, since the electrodes usually use a catalyst mainly composed of platinum, when the battery starts up,
If a cooling gas containing a flammable gas is introduced into the reaction gas chamber before the battery is sufficiently warmed up, there is a risk that the flammable gas will react with the platinum of the electrode and lose its catalytic activity. Therefore, a digas type battery in which the gas chamber is simply separated by a corrugated plate is insufficient.

Furthermore, in air-cooled fuel cells that use air as a reactant gas also as a cooling gas, water produced by the oxidation reaction comes into contact with the electrolyte, causing changes in the electrolyte concentration Hiratani product within the cell and local heating of the electrodes. -This may lead to deterioration of the catalyst.

[Embodiments of the invention]

FIG. 2 shows an embodiment of the present invention, in which the present invention is applied to the fuel cell shown in FIG. 3 described above.

In the figure, the separate plate 2 is a combination of upper and lower divided plates 2a and 2b superimposed, and the upper divided plate 2a of each divided plate 2a and 2b has an upper surface similar to that shown in FIG. A reactive gas supply passage 3 for fuel gas is formed on the lower surface of the lower dividing plate 2b, and a reactive gas supply passage 4 for air similar to that shown in FIG. 6 is formed on the lower surface of the lower dividing plate 2b.
(b) Concave grooves 5a and 5b are formed correspondingly on the mutual joint surfaces so as to merge with each other to form a tunnel-shaped cooling medium passage 5. The heat medium passage of the present invention is formed in this. A catalyst layer 9 made of platinum is uniformly formed on the P'[i-plane of the grooves 5a and 5b.

The catalyst layer 9 formed on the inner surface a of the grooves 5a and 5b is formed in the grooves tit 5a of the reaction gas supply passage 3 and the cooling medium passage 5, and the reaction gas supply passage separately on each dividing plate 2a + 2b. After forming the grooves 4 and 5b by cutting or molding, the concentration is adjusted so that the amount of oxidation catalyst is supported on the inner wall surfaces of the grooves 5a and 5b from 0.05 to 0.1 per unit area of the wall surface. The platinum salt aqueous solution was coated and impregnated, dried, and then reduced in a hydrogen atmosphere at 200 to 300°C for 2 to 4 hours.

FIG. 1 shows an embodiment of the present invention for raising the temperature at the time of starting up a fuel cell in which a large number of such separate plates are assembled and stacked. In the figure, a fuel cell power generation plant 21 includes a fuel cell body n, a fuel reformer n, and piping for supplying natural gas such as methane or fuel such as methanol to the reformer.

A fuel reforming system 40 consisting of a pipe δ that guides a part of the fuel to the reforming burner, a pipe addition for supplying reformed gas to the fuel cell, a blower n that supplies air to the fuel cell, and a blower n that supplies cooling air. Between the air supply system including a blower for supplying air and piping 4, 30 for guiding each air to the fuel cell, an orthogonal conversion device t31 that converts the DC current generated by the battery into an AC current, and the reaction flow rate, It consists of an illD device 32 that controls pressure, temperature 2, etc.

In a fuel cell power generation plant having such a configuration, in order to raise the temperature of the fuel cell main body from a stopped state to the starting temperature, a part of the reformed gas reformed in the fuel reformer n is transferred to the gas mixer. g! is supplied from the cooling air blower. This mixed gas is introduced into the cooling medium passage of the fuel cell body covered with a catalyst, and the platinum in the catalyst layer 9 reacts with the flammable gas and the heat of oxidation causes the separation plate to 2, the temperature of the main body tube can be raised quickly. In addition, to prevent excessive heating, the temperature of the separate plate 2 should be constantly monitored while the temperature of the battery is rising, and the mixing ratio of reformed gas and air in the gas mixer should be controlled to a constant value. Bye.

In the above embodiment, a method was described in which the reformed gas reformed in the reformer n is mixed with air and guided to the cooling medium passage, and the temperature of the battery body is raised by the oxidation heat of the reformed gas.
If the inner wall of the cooling medium passage is covered with a catalyst that can directly oxidize natural gas such as methane, ethane, propane, or methanol, the mixed gas of these flammable gases and air can be directly oxidized as a cooling medium. It is also possible to raise the temperature of the fuel cell body by guiding it to the passage. In addition to platinum, palladium or a complex of platinum and palladium can be used as the combustible oxidation catalyst.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, a catalyst is provided in a heating medium passage isolated from the electrolyte of a battery, and a flammable gas is introduced into this heating medium passage when the battery is started up, and the catalyst and combustible gas are introduced into the heating medium passage. Since the battery body is directly heated by the heat of oxidation caused by the reaction with the oxidizing gas, the temperature of the battery body can be quickly raised when the battery is started.

[Brief explanation of drawings]

Fig. 1 is a system configuration diagram of a fuel cell power generation plant showing an embodiment of the present invention, Fig. 2 is a partially exploded perspective view of a separate plate showing an embodiment of a heat medium passage according to the invention, and Fig. 3 is a system configuration diagram of a fuel cell power generation plant showing an embodiment of the present invention. FIG. 4 is a partially cross-sectional side view showing the configuration of one cell of a fuel cell. FIG. 4 is a cross-sectional view taken along the arrow ■-■ in FIG. It is a top view of a lower surface. 2: Separate plate, 3.4: Reaction gas supply path, 5: Cooling medium passage %9: Catalyst skin, 21: Fuel cell power generation plant,
22: Fuel cell body, 23: Reformer, Sae, 25, 26,
29, 30: Piping, 27, 28 Niblower, 31:
Orthogonal transformation device, 32: Control device, A: Gas mixer, 40
:Fuel reforming system, two-way air supply system. 2 years old 4 figures

Claims (1)

[Claims] 1) In an air-cooled fuel cell in which a heat medium independent of the reactant gas is supplied to a heat medium path isolated from the electrolyte, a catalyst is provided in the heat medium path, and this heat is removed when the cell is started. A method for increasing the temperature of an air-cooled fuel cell, characterized by introducing flammable gas into a medium passage. 2) A method for starting an air-cooled fuel cell according to claim 1, characterized in that part of the fuel gas is used as the combustible gas. 3) A method for increasing the temperature of an air-cooled fuel cell according to claim 1, characterized in that a catalyst layer is uniformly formed in the heat medium passage.