Solid oxide fuel cell systems and methods of operating solid oxide fuel cell systems

A solid oxide fuel cell system comprising:

• a solid oxide fuel cell stack comprising an anode, a cathode, and a solid electrolyte;
• a cathode gas source operable to pass a cathode gas through the cathode of the solid oxide fuel cell stack;
• an anode gas source operable to pass an anode gas through the anode of the solid oxide fuel cell stack, the anode gas source comprising an autothermal reformer operable to produce the anode gas by the autothermal reforming of a hydrocarbon fuel;
• an anode gas regulator operable to regulate the flow of the anode gas through the anode of the solid oxide fuel cell stack by diverting at least a portion of the anode gas to bypass the solid oxide fuel cell stack, where the anode gas regulator comprises an inlet valve disposed on an inlet side of the solid oxide fuel cell stack, an outlet valve disposed on an outlet side of the solid oxide fuel cell stack, and a temperature sensor operable to measure the temperature of the solid oxide fuel cell stack;
• and
• a heat exchanger interposed between the cathode gas source and the cathode as well as a downstream portion of the outlet valve and an upstream portion of the inlet valve, wherein the heat exchanger is configured to
• receive the cathode gas from the cathode gas source, and
• receive an anode discharge from the outlet valve, the anode discharge comprising the portion of the anode gas diverted by the anode gas regulator and an unreacted portion of the anode gas passed through the anode.