Patent ID: 6033794
Filing Date: 2000-03-07
Classification: H01M,Y02E

Abstract:
A method for operating a multi-stage fuel cell system, comprising the steps of:providing a plurality of fuel cell stages, each fuel cell stage having fuel and oxidant process stream inlets and outlets for conducting process streams through the fuel cell stage, and each fuel cell stage containing at least one fuel cell;designing each fuel cell stage to operate within a desired temperature range, such that the multi-stage fuel cell system is comprised of fuel cell stages that operate at non-uniform temperatures;assembling the plurality of fuel stages into the multi-stage fuel cell system by arranging the fuel cell stages in a series according to their operating temperature ranges, wherein downstream fuel cell stages accommodate progressively higher temperature fuel and oxidant streams than upstream stages, and connecting the process stream outlets of an upstream stage with the process stream inlets of an adjacent downstream stage;supplying a fuel process stream and an oxidant process stream to the multi-stage fuel cell system; andunderutilizing the fuel process stream in each fuel cell stage, such that the fuel process stream flowing through a fuel cell stage has an excess amount of fuel than the amount of fuel consumed by that fuel cell stage.