Process for operating a hydrogen production apparatus and apparatus for producing hydrogen for fuel cells

Process for operating an apparatus for producing hydrogen for operating fuel cells comprises supplying a defined quantity of process heat from a heat source (2) designed as a burner to a reformer (1) having downstream catalyst stages (3) for converting hydrocarbon gas and water into hydrogen and other reformer products. When required, additional heat is released which is removed from the apparatus for a separate use. In this case an additional exhaust gas flue (4) is opened to remove the heat unaffected by the reformer process using a heat exchanger (5) arranged in the exhaust gas flue. An Independent claim is also included for an apparatus for producing hydrogen for operating fuel cells.