Apparatus and method for operation of a high temperature fuel cell system using recycled anode exhaust

摘要

A method for improving the efficiency of a hydrocarbon catalytic reformer and close-coupled fuel cell system by recycling a percentage of the anode exhaust syngas directly into the reformer in a range between about 20% and about 60%. Oxygen is supplied to the reformer (12) at start-up. Under equilibrium conditions, oxygen required for reforming of hydrocarbon fuel is derived entirely from endothermic reforming of water and carbon dioxide in the recycled syngas. Recycling of anode syngas into the reformer increases fuel efficiency, adds excess water to the reformate to increase protection against anode coking, and protects the fuel cell stack (16) against air- and water-borne contaminants. A method for producing an excess amount of syngas for exporting for other purposes is also provided.