JP2815690B2 - Startup control device for liquid electrolyte fuel cell - Google Patents

Description

Description: BACKGROUND OF THE INVENTION The present invention relates to a liquid-electrolyte fuel cell power generator, and more particularly, to a fuel cell having a start-up control device that raises the temperature from a storage temperature to an operating temperature when the fuel cell is started. It relates to a power generator.

[Conventional technology]

This type of fuel cell has an electrolyte chamber filled with, for example, a potassium hydroxide aqueous solution as a liquid electrolyte, and a fuel electrode and an oxidant electrode arranged on both sides of the electrolyte chamber so as to face each other. It is well known that power is generated by an electromotive reaction inside an electrode by supplying a fuel gas (hydrogen) and an oxidizing gas (air) to each electrode through each reaction gas chamber. It is on the street. Further, this electromotive reaction is an exothermic reaction, and hydrogen and oxygen react to generate water on the fuel electrode side.

When the generated water accumulates inside the battery as it is and dissolves in the liquid electrolyte, the electrolyte is diluted, and the electromotive reaction gradually decreases. For this purpose, as a management method for maintaining an appropriate concentration of the electrolyte, a suitable amount of the reaction gas is circulated and blown, the generated water is taken out of the fuel cell as water vapor, and is condensed and separated by a condenser installed at the outlet of the fuel cell. Methods are known. The circulation amount of the reaction gas is determined and controlled by an arithmetic and control unit so that the generated water amount and the condensed water amount substantially match.

By the way, a fuel cell has an operating temperature (usually 100 ° C. or lower) suitable for an electromotive reaction, and it is necessary to raise the temperature from a stored state to the operating temperature at the time of startup. Conventionally, as this method, a fuel cell has a built-in electric heater and is heated by supplying current from a power source such as a battery at the time of startup. Alternatively, a load resistance is connected to the electric output side of the fuel cell to energize the fuel cell, and the temperature is raised by the heat generated by the electromotive reaction of the fuel cell itself.

[Problems to be solved by the invention]

By the way, the conventional fuel cell starting method described above has the following problems.

(1) Attached devices such as an electric heater and an auxiliary battery are required as a heating means, and the size of the device is increased due to this.

(2) The generated water is generated even when the power generation temperature rises due to the load resistance. When the temperature of the fuel cell is low, the saturated steam pressure is low, and the amount of removed water that can be separated by the condenser is small. Can not completely remove the generated water,
The dilution of the electrolyte cannot be avoided.

(3) In order to avoid the above problem (2), a method is also known in which the amount of generated water is suppressed by extremely reducing the current flowing to the resistance load. However, this method requires a long time for starting. As a result, the usability of the power generator itself becomes poor.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a start-up control device capable of quickly raising the temperature of a fuel cell without causing dilution of an electrolyte by sufficiently utilizing the capacity of a condenser or a blower.

[Means for solving the problem]

In order to solve the above-described problems, according to the present invention, an electrolyte chamber filled with a liquid electrolyte, a porous fuel electrode and an oxidant electrode disposed opposite to each other with the electrolyte chamber interposed therebetween A stacked body of a plurality of unit cells each having a reaction gas chamber for supplying and discharging hydrogen and an oxidant as a reaction gas to both electrodes, and a forced circulation path of the reaction gas on the fuel electrode side; A short circuit having a current sensor, a variable resistor, and a switch provided on the output side of the fuel cell; and a condenser for separating the power generation water contained in the reaction gas. Sensors for detecting the reaction gas temperatures at the inlet and outlet of the reactor, the amount of generated water generated based on a predetermined formula including the current detected by the current sensor, and the condensation obtained based on the temperatures detected by the pair of temperature sensors Vessel removal An arithmetic control unit for determining an amount and a current value that generates an amount of generated water equal to the amount of the removed water, and detecting a signal for controlling the variable resistor so that the obtained current value flows through the short circuit. It shall be.

[Action]

In the configuration of the present invention, the arithmetic and control unit determines the amount of generated water generated in proportion to the output current, the amount of generated water removed corresponding to the temperature difference between the inlet and outlet of the condenser, and the current value in which both are equal to each other. By controlling the current flowing in the short circuit based on the current value, the generated water corresponding to the power consumption of the variable resistor arranged in the short circuit is always balanced with the amount of water removed from the condenser. As the temperature of the fuel cell increases, the amount of generated water removed also increases, and the power consumption of the variable resistor can be increased accordingly. Thus, the capacity of the condenser and the blower that circulates the reaction gas to the condenser is increased. In addition to the function of efficiently raising the temperature of the fuel cell from its storage temperature to the operating temperature, the liquid electrolyte is diluted by the generated water, and this causes the fuel cell to generate power. Ability can be prevented a situation to decrease.

〔Example〕

 Hereinafter, the present invention will be described based on examples.

FIG. 1 is a system flow diagram showing a fuel cell power generator according to an embodiment of the present invention. In the figure, reference numeral 1 denotes a liquid electrolyte fuel cell, which includes an electrolyte chamber 2 filled with a liquid electrolyte, a porous hydrogen electrode 3 and an oxidant electrode 4 opposed to both sides of the electrolyte chamber 2 with the electrolyte chamber 2 interposed therebetween. A hydrogen chamber 5 and an oxidant chamber 6 are formed on both sides of each of the electrodes 3 and 4 by, for example, a ribbed separate plate. At the inlet of the hydrogen chamber 5, a fuel gas supply pipe 10 drawn from a gas source such as a hydrogen gas cylinder (not shown) is connected and connected. Further, a blower 11 is provided between the outlet and the inlet of the hydrogen chamber 5. A fuel gas circulation path 12 is provided, and a condenser 13 is installed on the hydrogen chamber outlet side of the circulation path 12. Reference numeral 18 denotes an oxidant, for example, an air supply pipe connected to the oxidant chamber 6, 9 denotes a cooling fan of the fuel cell, and 20 denotes a cooling fan of the condenser 13.

On the other hand, a short circuit 19 including a cutoff switch 29 and a variable resistor 30 is provided between the poles of the output circuits 7 and 8 of the fuel cell, and a current sensor 24 for output detection is provided in the electric output circuit of the fuel cell. Circulator 13 in the fuel gas circuit 12
Before and after, temperature sensors 25 and 26 for detecting the reaction gas temperature are provided, and the detection signals of the current sensor 24 and the temperature sensors 25 and 26 are input to the arithmetic and control unit 27, and the variable resistor disposed on the short circuit 19 side. An operation for obtaining a signal 27S for controlling the resistance value of 30 is performed. That is, the output current of the fuel cell 1 detected by the current sensor 24 I, if the number of stacked unit cells in the fuel cell 1 is N, the generation amount V ₁ of the product water generated by the fuel cell 1 during operation of the Faraday It is obtained by the following equation based on the law.

V ₁ = I × (60/96480) × (18.02 / 2) × N (1) On the other hand, the amount of hydrogen circulated by the blower 11 is Q, the number of moles thereof is m, and the volume of one mole of complete gas is V ₀ , when the saturation of steam at the condenser outlet is K, the steam partial pressure ratio (steam partial pressure / hydrogen partial pressure) in the circulating gas in a saturated state depends on the temperature of the circulating gas. removal amount V ₂ of produced water that is separated is calculated from the following equation.

Therefore, simultaneously with the operation control unit 27 receives the detection signal of the current sensor 24 obtains the amount of produced water V ₁ on the basis of the above (1), based on the temperature detected by the temperature sensor 25 and 26 (2) formula calculating the calculated removal amount of water V ₂ go, and with a water quantity V ₁ and removing water V ₂ is calculated equal such currents I together, in the variable resistor 30 to flow the current I to the short circuit 19 by outputting a signal 27S for controlling the resistance value, the amount of produced water V ₁ generated in the fuel cell 1 during startup condenser 13
In the condensation, it can be started in a state where the amount of water removed V ₂ to be separated is always balanced. Further, if the above calculation is repeatedly performed at predetermined time intervals and the variable resistor 30 is controlled based on the updated control signal, the calculation result is increased in accordance with the temperature rise of the fuel cell 1 and the temperature of the circulating gas. Gradually rises, and the current flowing through the short circuit 19 gradually increases based on this. Therefore, the fuel cell is stored by self-heating by making full use of the circulation gas amount Q by the blower and the condensation performance of the condenser. It is possible to obtain a startup control device capable of raising the temperature from the temperature to the operating temperature in the shortest time.

The switch 29 of the short circuit 19 is configured to be closed by a start command signal generated by the arithmetic control unit 27 and to be opened by a start end signal generated when the fuel cell 1 reaches a predetermined operating temperature.

By providing the start-up control device according to the above-described embodiment, the temperature rises due to self-heating while always balancing the amount of generated water and the amount of generated water removed to the outside of the cell in accordance with the temperature condition of the fuel cell. Therefore, it is possible to maintain the concentration of the electrolyte constant regardless of the number of times of starting / stopping, and therefore, it is possible to almost completely avoid a decrease in the power generation performance of the fuel cell caused by diluting the electrolyte with the produced water. be able to.

Also, unlike the conventional method of controlling the amount of circulating gas in the gas circulation path so that the amount of water generated by the fuel cell and the amount of water removed by the condenser substantially match, the amount of generated water itself is controlled by controlling the current flowing through the short circuit. Since the control is performed in accordance with the amount of water removed, the concentration of the electrolyte solution can be controlled with high accuracy.
There is also an advantage that it becomes possible to control the concentration of the electrolyte solution itself by the method of selecting.

〔The invention's effect〕

According to the present invention, as described above, based on the detection signals of the current sensor and the temperature sensor, the arithmetic and control unit obtains a current value that generates water equivalent to the amount of water removed by the condenser, and calculates a current value flowing through the short circuit as a calculation result. A control signal is output to the variable resistor. As a result, it is possible to raise the temperature of the fuel cell from its storage temperature to the operating temperature by self-heating while always balancing the amount of generated water at the time of starting the fuel cell and the amount of water removed by the condenser, and increase as the temperature rises It is possible to control to increase the current value in accordance with the amount of water to be removed, to make full use of the capacity of the condenser and the circulating blower to efficiently raise the temperature of the battery, and to dilute the liquid electrolyte with the generated water. It is possible to provide a liquid electrolyte fuel cell provided with a start-up control device that can be performed without any problem.

In addition, the adverse effect of generated water at the time of low temperature at the beginning of start-up, which has been a problem in the prior art for controlling the circulation amount of the reaction gas so that the generated water amount and the removed water amount substantially match, always balances generation and removal. Can be avoided almost completely. Furthermore, in comparison with the conventional technology in which an electric heater is embedded in a fuel cell and power is supplied from a battery power source to heat the fuel cell, the present invention uses a built-in electric heater and a battery power source to perform heating by self-heating. No equipment is required, so the structure of the device can be simplified, and maintenance work can be simplified because there is no need to charge the battery, and the temperature can be raised in a short time regardless of the repeated start and stop operations. And other advantages.

[Brief description of the drawings]

FIG. 1 is a simplified system flow diagram showing a startup control device for a liquid electrolyte fuel cell according to an embodiment of the present invention. 1: fuel cell, 2: electrolyte chamber, 3, 4: electrode, 5, 6: reaction gas chamber,
7, 8: output circuit, 9, 11, 20: blower, 10, 18: reaction gas supply system, 12: gas circulation path, 13: condenser, 19: short circuit, 24: current sensor, 25, 26: Temperature sensor, 27: arithmetic control unit, 29: switch, 30: variable resistor, 27S: control signal, I: output current.

Continuation of the front page (72) Inventor Akira Nitta 2-1-1-11 Tagawa, Yodogawa-ku, Osaka-shi, Osaka Daihen Co., Ltd. (58) Field surveyed (Int. Cl. ⁶ , DB name) H01M 8/00- 8/24

Claims (1)

(57) [Claims] An electrolyte chamber filled with a liquid electrolyte, a porous fuel electrode and an oxidant electrode disposed on opposite sides of the electrolyte chamber, and hydrogen as a reaction gas And a reaction gas chamber for supplying and discharging an oxidant. The reaction cell chamber is composed of a plurality of unit cells each having a reaction gas chamber for supplying and discharging an oxidant. A condenser for separating generated water, a current sensor provided on the output side of the fuel cell, a short circuit having a variable resistor and a switch, and a reaction gas temperature at the inlet and outlet of the condenser. A detection sensor, an amount of generated water generated based on a predetermined formula including a current detected by the current sensor, an amount of water removed from the condenser obtained in accordance with a temperature detected by the pair of temperature sensors, and an amount of water removed from the condenser. Generating Equivalents And a calculation control unit for detecting a signal for controlling the variable resistor so that the obtained current value flows through the short circuit. Startup control device.