A control method and arrangement (48, 50, 150, I, T, P, FFL) are provided
in a fuel cell power plant (10) for regulating (48, FC) fuel flow to a
steam-based fuel processing system (FPS) (14) associated with a
low-temperature fuel cell stack assembly (12). A portion of the fuel
provided by the FPS (14) is used to provide steam for the FPS. The fuel
flow to the FPS is regulated as a function of the power demand (I) on the
fuel cell (12) and at least the enthalpy of the steam (P, T), such that
the steam enthalpy is regulated to meet increases and decreases in power
demand without exceeding steam pressure limits. In addition to reliance
on-steam pressure (P) as a fundamental measure of steam enthalpy, the
control may additionally use reaction temperature (T) at, or in, a
reformer, such as a catalytic steam reformer (132), to regulate fuel flow
and thus, steam enthalpy.
