US 7,732,073 B2 · Fuel cell minimum fuel recycle with maximum fuel utilization

Abstract

Recycle fuel gas is provided (36) to an impeller (34, 34a) for application to the input (24) of the anode flow fields of a fuel cell stack (25). The impeller may be an ejector (34) having its primary input (33) connected to a source (11) of hydrogen and its secondary input (35) connected to the outlet (27, 37) of the fuel cells anode flow fields. The ejector outlet provides the minimum fuel flow required at the lowest power rating. The impeller may be an electrochemical hydrogen pump (34a) with a constant current generator (50) providing for a substantially constant recycle flow (the highest not more than double the lowest), and one pressure regulator (20) providing minimum flow of fresh fuel to the fuel inlets of the first stack. Pressure regulators (20, 21) control the amount of fresh fuel to the anode flow fields for power in excess of minimum power.

Claims14

Dependent claims

A method of operating a fuel cell power plant which comprises providing a flow of fuel recycle gas having a substantially constant quantity of recycle fuel therein at all levels of power output, said flow of fuel recycle gas having a sufficient quantity of recycle fuel therein at a minimum level of power output to avoid fuel starvation within said fuel cell power plant at said minimum level of power output.

A fuel cell power plant operable at power output levels between a full rated power output level and a minimum power output level, comprising:

a plurality of fuel cells, each having a fuel inlet and a fuel outlet, said fuel cells arranged in one or more stacks selected from (a) one stack comprising the first and last stack in said fuel cell power plant or (b) a series of stacks arranged in serial fuel flow relationship such that every stack except a last stack in said series provides fuel to a stack next subsequent thereto in said series, and every stack except a first stack in said series receives fuel from a next preceding one of said stacks in said series, each stack having a fuel inlet and a fuel outlet;
a source of fuel for providing fresh fuel to the fuel inlet of at least one of said stacks;
and
a passive fuel recycle gas pump providing recycle fuel gas flow from the fuel outlet of at least one of said stacks to the fuel inlet of one or more of said stacks in substantially constant quantity, at all of said power output levels, said substantially constant quantity being sufficient to prevent fuel starvation of said fuel cells when operating near maximum fuel utilization at minimum power.

1 more element

Dependencies are inferred from the claim text.

Fuel cell minimum fuel recycle with maximum fuel utilization

Life of this patent

Fuel cell minimum fuel recycle with maximum fuel utilization

Life of this patent

Abstract

Claims14