US 5,308,456 AGranted

Molten carbonate fuel cell sulfur scrubber and method using same

AssigneeInternational Fuel Cells Corporation

InventorsHarold R. Kunz, Richard A. Sederquist, Ole L. Olesen

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Abstract

Sulfur compounds poison catalysts, such as the anode catalysts and reformer catalysts within molten carbonate fuel cell systems. This poisoning is eliminated using a sulfur scrubber 29 located prior to the inlet of the cathode chamber 13. Anode exhaust 19 which contains water, carbon dioxide and possibly sulfur impurities, is combined with a cathode exhaust recycle stream 22 and an oxidant stream 25 and burned in a burner 33 to produce water, carbon dioxide. If sulfur compounds are present in either the anode exhaust, cathode exhaust stream, or oxidant stream, sulfur trioxide and sulfur dioxide are produced. The combined oxidant-combustion stream 27 from the burner 33 is then directed through a sulfur scrubber 29 prior to entering the cathode chamber 13. The sulfur scrubber 29 absorbs sulfur compounds from the combined oxidant-combustion stream 27. Removal of the sulfur compounds at this point prevents concentration of the sulfur in the molten carbonate fuel cell system. Therefore, neither the reformer catalysts nor the anode 17 experience sulfur poisoning.

Claims18

Dependent claims

A method for removing sulfur from a molten carbonate fuel cell system, said system having a burner, a molten carbonate fuel cell, said molten carbonate fuel cell having an anode, a cathode, a molten carbonate electrolyte disposed therebetween, an anode chamber and a cathode chamber, which comprises the steps of:

a. introducing a fuel stream containing hydrogen to the anode chamber where said fuel system contacts said anode,
b. reacting said hydrogen at said anode with carbonate ions to form carbon dioxide, water and free electrons, where sulfur compounds in said fuel stream and on the anode react with hydrogen to form hydrogen sulfide;
c. removing the fuel stream, including the carbon dioxide, water, and any hydrogen sulfide from the anode chamber as anode exhaust,
d. introducing an oxidant stream to a sulfur scrubber wherein said sulfur scrubber removes sulfur compounds from said oxidant stream to form a scrubbed stream;
e. introducing said scrubbed stream to the cathode chamber where said scrubbed stream contacts said cathode;
f. reacting carbon dioxide and O.sub.2 in said scrubbed stream with said free electrons which passes from the anode to the cathode to produce carbonate ions which migrate across the molten carbonate electrolyte to the anode;
and
g. removing said scrubbed stream from said cathode chamber as a cathode exhaust stream.

5 more elements

Dependencies are inferred from the claim text.