JPH07169493A - Combustible gas purge device for fuel cell power plant - Google Patents

Abstract

PURPOSE:To purge a combustible gas in a system without using nitrogen gas by providing an exhaust gas purge line for purging a plant internal combustible gas with the plant exhaust gas in a fuel cell power plant. CONSTITUTION:The exhaust gas of a fuel cell power plant 1 is sucked by the exhaust cylinder 2 of the plant 1. The exhaust gas is passed through an oxygen adsorber 3, whereby the concentration of the oxygen in the exhaust gas is reduced to zero or a low concentration lower than the ignition concentration. To confirm this, an oxygen densitometer 4 is set on the outlet port of the oxygen adsorber 3 for monitoring and protection. The inactivated exhaust gas is raised in pressure by a booster 5, and stored in a reservoir tank 7 after the moisture is removed by a dehumidifier 6. When the plant is stopped, the exhaust gas stored in the reservoir tank 7 is used to purge the combustible gas in the plant. This combustible gas purge device allows to set a fuel cell power plant in a place difficult to supply nitrogen gas.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustible gas purging device for a fuel cell power plant.

[0002]

2. Description of the Related Art A fuel cell power plant is used not only as an electric power source for private power generation but also as a hot water supply, cooling and heating, and other heat utilization by taking advantage of the fact that it is close to the place of demand.

A power plant using a fuel cell is highly efficient even in a small size, can diversify fuels, and can effectively utilize exhaust heat. It has some excellent features such as being able to be installed near the site. Therefore, the introduction is planned actively in each field, and the installation of demonstration plants is also active.

It is also promising as a future power generator that NOX, SOX, dust and the like in the exhaust gas have extremely low values as compared with other power generation facilities. Gas that can be used as fuel is also retained in the fuel cell. Although it is consumed by the battery main body during operation, unreacted combustible gas remains in the equipment and the pipes when stopped. In order to ensure safety, this flammable gas is released from the inside of the system to the outside of the system by using an inert gas.

[0005]

Nitrogen gas is usually used as the inert gas. Therefore, the fuel cell power generation plant has a nitrogen gas cylinder or a liquefied nitrogen storage device regardless of its size. An object of the present invention is to provide a fuel cell power plant having a device for reducing the nitrogen gas storage device and for purging combustible gas in the system without using N ₂ gas (nitrogen gas).

[0006]

Exhaust gas from a fuel cell power plant is the gas with the lowest oxygen concentration of all the gases handled. The oxygen content in the exhaust gas is reduced to zero or a low concentration without fear of ignition, and is used for purging as a substitute for nitrogen gas as an inert gas.

[0007]

[Function] Oxygen in the exhaust gas is removed by an adsorber to form an inert gas.

[0008]

FIG. 1 shows an embodiment of the present invention. The exhaust gas of the plant is sucked from the exhaust stack 2 of the fuel cell power generation plant 1. By passing the exhaust gas through the oxygen adsorber 3,
Oxygen in the exhaust gas is reduced to zero or a low concentration below the ignition concentration. For confirmation, an oxygen concentration meter 4 is installed at the outlet of the oxygen adsorber 3 for monitoring and protection. The inactivated exhaust gas is boosted by the booster 5, has its moisture removed by the dehumidifier 6, and is then stored in the reservoir tank 7. The exhaust gas stored in the reservoir tank 7 when the plant is stopped is used to purge the combustible gas in the plant.

The nitrogen gas used as the inert gas is no longer needed, and the storage facility for it becomes unnecessary. A combustible gas such as hydrogen gas is injected into the exhaust gas and is oxidized by the catalytic oxidizer 8 to reduce the oxygen concentration. Further, the recycle blower 9 is used to recirculate to the inlet to further reduce the oxygen concentration. For monitoring, the oxygen concentration meter 4 and the combustible gas meter 10 provide monitoring protection.

[0010]

According to the present invention, a fuel cell power plant can be installed even in a place where it is difficult to supply nitrogen gas.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a flammable gas purging device according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of a flammable gas purging device according to another embodiment of the present invention.

[Explanation of symbols]

 1 ... Fuel cell power plant 2 ... Exhaust stack 3 ... Oxygen adsorber 4 ... Oxygen concentration meter 5 ... Booster 6 ... Dehumidifier 7 ... Reservoir tank 8 ... Catalytic oxidizer 9 ... Reservoir tank 10 ... Combustible gas meter

Claims (2)

[Claims] 1. A combustible gas purge device for a fuel cell power plant, comprising an exhaust gas purge line for purging the combustible gas in the plant with the plant exhaust gas in the fuel cell power plant. 2. The flammable gas purging apparatus for a fuel cell power plant according to claim 1, wherein a flammable gas remover, a booster, a dehumidifier, and a reservoir tank are provided in the exhaust gas purge line.