JPS6011426B2 - Fuel cell - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel cell capable of replacing a reactive gas in at least one gas chamber with an inert gas by supplying an inert gas from the outside.

In a fuel cell power generation system that combines a fuel cell with an inverter to supply power to an AC system, the method of cutting off the DC circuit to protect against overcurrent in the event of an inverter commutation failure is a technological challenge for large-capacity systems. This requires low-voltage, high-current, high-speed direct current and disconnection, which is extremely difficult.

As a result of various studies to overcome this problem, we decided to stop the discharge of the fuel cell by replacing the reactive gas in the gas chamber on either the oxidizer side or the fuel side of the fuel cell with an inert gas. We discovered that this method was extremely effective and developed it. There are two ways to replace the reactive gas in the gas chamber with an inert gas: supplying an inert gas source from outside, and in fuel cells that use air as an oxidizer, replacing the gas from the gas chamber. One possible method is to accumulate nitrogen, which is an inert gas in the air, in the gas chamber by stopping the fuel cell, but the present invention is directed to a fuel cell in which the power supply can be stopped using the former method. The purpose of this invention is to provide a fuel cell that takes into consideration the distant replacement of reactant gas and inert gas and the constant maintenance of the cell internal pressure during and after direct exchange. This object is achieved according to the invention by the features described in the claims. Hereinafter, the present invention will be explained in detail with reference to embodiments shown in the drawings.

The figure only schematically shows the gas circuit system for one of the reactant gases of the fuel cell according to the invention.

In this figure, the cell indicated at 6 is supplied with both reactant gases, fuel and oxidizer, but the reactant gases guided by the gas circuit system according to the invention may be one of them and therefore the other. The gas circuit system for the reaction gas may have exactly the same configuration as the conventional one. For example, air or oxygen, which is an oxidizing agent, is supplied as one of the reaction gases into the cell 6 by opening the supply valve 1 and the discharge valve 2, and unreacted gas and reaction products are discharged from the cell. A reaction gas pressure regulator 3 is disposed between the supply valve 1 and the gas inlet of the cell 6 . This pressure regulator 3 functions to adjust the pressure within the cell to be substantially constant. For this purpose, for example, the pressure near the cell inlet is fed back. Further, in order to stop the power generation of the fuel cell, in accordance with the present invention, inert gas is supplied from an inert gas source (not shown) to the cell 6 side with respect to the reaction gas pressure regulator 3 via the inert gas supply valve 4. A pipe is provided, which is connected to the inert gas supply valve 4 via another pressure regulator 5. The pressure regulator 5 also serves to maintain the pressure on its outlet side, and therefore the pressure inside the cell, approximately constant. 'Both pressure regulators 3 and 5 are provided with a backflow prevention function as usual. The pressure of the inert gas pressure regulator 5 can also be set higher than that of the reaction gas pressure regulator 3. The reaction gas supply valve is activated by a control device (not shown) based on a power generation stop command issued when an overcurrent due to some kind of failure is detected in the electrical system of the fuel cell (not shown) or in the load circuit that receives power from the fuel cell. 1 is closed, and at the same time, the inert gas supply valve 4 is opened.

As a result, inert gas is supplied into the cell 6.
As the inert gas concentration in the gas chamber within the cell increases, the fuel cell voltage decreases, and power generation eventually stops.
Therefore, the power supply can be stopped without interrupting the direct current circuit on the output side of the fuel cell, and without allowing the overcurrent to reach the alarm level. According to the fuel cell according to the present invention, the structure is such that switching between the reactive gas and the inert gas is performed not at the inlet side of the reactive gas pressure regulator 3 but at the outlet side, so that the replacement operation with the inert gas within the cell is performed. The delay in the rise of can be minimized.

Further, by providing the inert gas pressure regulator 5, the pressure inside the cell can be kept almost constant during the replacement operation and after the replacement operation is completed, and characteristic deterioration due to deformation of the electrodes inside the cell can be prevented. Moreover, by providing separate pressure regulators for the reaction gas and the inert gas, different pressure settings can be given to each other. In other words, the pressure setting of the inert gas pressure regulator can be increased in order to further reduce the time required to replace the reaction gas in the gas chamber with inert gas. The discharge valve 2 should be closed by a power generation stop command signal in order to reduce the amount of inert gas required each time.

However, instead of closing the discharge valve 2 at the same time as the reaction gas supply valve 1 and the inert gas supply valve 4, if the discharge valve 2 is delayed by a suitable time element, it is possible to The residual reaction gas in the piping can be forcibly pushed out by supplying an inert gas, and therefore the replacement rate can be increased.

[Brief explanation of the drawing]

The figure is a schematic diagram of the main parts of a fuel cell according to the present invention. 1...Reaction gas supply valve, 2...Discharge valve, 3...Reaction gas pressure regulator, 4...Inert gas supply valve, 5... ...Inert gas pressure regulator, 6.
…··cell.

Claims (1)

[Scope of Claims] 1. A fuel in which a pressure regulating element is disposed between a reaction gas supply valve and a gas inlet of the cell in order to supply the reaction gas into the cell while keeping the internal pressure of the cell substantially constant. In the battery, an inert gas supply valve that is opened when the reaction gas supply valve is closed by a signal instructing to stop power supply to the fuel cell;
A fuel cell characterized in that another pressure regulating element is provided between the inert gas supply valve and the gas inlet of the cell and guides the inert gas into the cell while keeping the cell internal pressure substantially constant. 2. In the fuel cell according to claim 1, the cell internal pressure adjusted by the inert gas side pressure regulating element is set higher than the cell internal pressure adjusted by the reactant gas side pressure regulating element. Characteristic fuel cells.