Fuel cell system and method for purging and draining water during shutdown and starting of fuel cell system

Abstract

The invention relates to a fuel cell system and a method for purging and draining water during shutdown and starting of the fuel cell system. The system comprises a fuel cell stack (1), an air compressor (2), an air inlet pipeline (3), an air exhaust line (4), a hydrogen supply system comprises a hydrogen storage tank, a hydrogen inlet pipeline (5) and a hydrogen exhaust pipeline; the air exhaustpipeline (4) is connected with a low-oxygen-concentration gas storage tank (7) through a branch pipeline (6); the low-oxygen-concentration gas storage tank (7) is in return connection with the hydrogen inlet pipeline (5) through a circulating pipeline (8); the power is continuously generated after the fuel cell is shut down; hydrogen remaining in the fuel cell stack (1) consumes oxygen in air on the cathode side, generated low-oxygen-concentration gas is used for purging residual hydrogen in the anode of the fuel cell stack, oxygen-containing gas on the anode side is purged during startup, safety is improved, and water in a flow channel on the anode side can be safely and efficiently discharged during shutdown.

Description

technical field [0001] The invention relates to a fuel cell, in particular to a fuel cell system and a method for purging and draining the fuel cell system when it is shut down and started. Background technique [0002] A fuel cell is a power generating device that directly converts the chemical energy of fuel into electrical energy. Its working principle is to convert the chemical energy in the material into electrical energy through electrochemical reaction, and the material required for the chemical reaction of the fuel cell is provided from the outside. As long as the fuel and oxidant are continuously supplied, the fuel cell will continuously output electrical energy and heat energy. . In short, a fuel cell is an energy conversion device. [0003] The proton exchange membrane fuel cell is an electrochemical power generation device that uses hydrogen as the fuel and oxygen as the oxidant. The hydrogen and air are passed into the anode and cathode respectively, and the g...

AI Technical Summary

Problems solved by technology

Therefore, the shutdown time of the fuel cell is long, especially, the remaining fuel gas and oxidant gas can permeate the electrolyte membrane, damage the electrode catalyst and the catalyst support, thereby shortening the service life of the fuel cell

Moreover, the fuel gas is generally flammable and explosive hydrogen. After the fuel cell is shut down, the residual hydrogen in the stack may easily cause safety accidents such as fire or explosion. Therefore, it is generally necessary to purge the stack after shutting down. The method is to use high-purity nitrogen for purging after shutdown, which wastes energy and takes up additional N 2 resource

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