Reformer and fuel cell system having the same

A reformer of a fuel cell system of the type where a reformer feed is preheated in a reformer feed preheat section and then introduced to a reforming reaction space in which the reformer feed is reacted to generate a reformed gas, the reformer comprising:

• a reforming reaction section comprising:
• a first pipeline defining an inlet to the reforming reaction space and an outlet from the reforming reaction space;
• a second pipeline having a cross sectional area smaller than the first pipeline, the second pipeline disposed within the first pipeline wherein the space between the first and second pipelines defines the reforming reaction space;
• an oxidation catalyst disposed in an internal space of the second pipeline;
• and
• a reforming catalyst disposed in the reforming reaction space;
• and
• a housing surrounding the reforming space and defining the reformer feed preheat section in which the reformer feed is preheated by direct contact with an outer wall of the first pipeline and from which the preheated reformer feed enters the inlet to the reforming reaction space.