Abstract: An autothermal reformer or a catalytic partial oxidizer (19) receives flow of desulfurized hydrocarbon fuel from a hydrogen desulfurizer (HDS) (15) through an orifice (13a). A differential pressure transducer (13b) provides a signal (24a) to a fuel-flow differential-pressure schedule (13c) to provide a fuel flow signal (24b) which is (25) subtracted from fuel command (26), to provide a valve position signal 30a from a proportional/integral gain (29), being linearized (58) to control the fuel valve (12). The minimum (59) of actual fuel flow (24b) and fuel flow command (59) is applied to an air/fuel schedule (33). The resulting air flow command is compared with actual air flow (41b) to provide an air flow control signal 48a which is linearized (60) after proportional/integral gain (47) to provide air flow command (48b) to a blower (49). Differential pressure (42b) across an orifice (42a) is provided to a schedule (42c) which converts to the actual air flow feedback (41b).