Patent ID: 7846594

Claim:
A fuel cell system comprising: a stack adapted to generate electric energy through a reaction between a hydrogen gas stream and oxygen; and a reformer adapted to generate the hydrogen gas stream from a fuel, wherein the reformer comprises: a first reaction section configured to receive a first portion of the fuel and to promote an oxidation reaction of the first portion of the fuel during start-up of the fuel cell system, thereby generating thermal energy, wherein the first reaction section comprises an oxidation catalyst for a catalytic oxidation reaction of carbon monoxide contained in the hydrogen gas stream during normal operation of the fuel cell system to thereby reduce the concentration of carbon monoxide in the hydrogen gas stream; a second reaction section which communicates with the first reaction section, and which is adapted to receive a remaining portion of the fuel other than the first portion and to promote a reforming reaction using the thermal energy, thereby producing the hydrogen gas stream from the remaining portion of the fuel; a third reaction section which communicates with the first and second reaction sections, and which is adapted to promote a catalytic oxidation reaction of carbon monoxide contained in the hydrogen gas stream to thereby reduce the concentration of carbon monoxide in the hydrogen gas stream, and a first vessel, a second vessel, and a housing, wherein the second vessel is disposed within the first vessel and the first vessel is disposed within the housing and the second vessel forms the first reaction section, the space between the first and second vessels forms the second reaction section, and the space between the first vessel and the housing forms the third reaction section, and wherein the second reaction section communicates with the first reaction section via a conduit, and an outer side wall portion of the second vessel extends beyond the first vessel to define a space between the outer side wall portion of the second vessel and the housing.