A thermally integrated reformer (10) is located inside the stack furnace (12) housing stacks (14) of solid oxide fuel cells (16). The energy to support the endothermic reformation reaction converting hydrocarbon and water feedstock into hydrogen and carbon monoxide fuel is supplied by heat recovered from the oxidation process in the stack (14) of fuel cells (16). The source of hydrocarbons is desulfurized natural gas. Heat transfers to reformers (10) which may be incrementally shielded packed beds (30, 60) of the reactors (18, 19) of the reformer (10) by radiation from the stacks (14), furnace wall (38), or both and by forced convection from the exhausting airflow exiting the stack furnace (12). Temperature gradients in the reformer (10) may be controlled by selective (or incremented) radiation shielding (20) and by counterflow heat exchange to prevent excessive premature cracking in the reformer. Such an optimized design uses a minimum amount of catalyst, yet prevents carbonization from clogging interstices or otherwise rendering the catalyst or catalyst granules (32) ineffective. Alternatively sufficient catalyst may be provided to render the reformation process a heat-limited reaction. In this circumstance, the stacks (132) configured in a module (106) may transfer heat directly to a reformer (110) surrounding the module (106). The air may pass through a heat exchanger 108 or preheater (200) positioned proximate the module 106 in an insulated enclosure (102).
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