Patent ID: 7691512

Claim:
A method of operating a fuel-cell power-generation system comprising the steps of: (i) circulating a first heating medium in a closed cooling-circulation system, which is different from pathways for a fuel and an oxidant to pass through a fuel cell, by operating a first heating-medium circulation means so that the first heating medium passes through the fuel cell and carries heat produced while the fuel cell generates power, (ii) circulating a second heating medium in a pipe by operating a second heating-medium circulation means so that the second heating medium recovers the heat, which is retained by the first heating medium, via a heat exchanger, (iii) continuing to operate the first heating-medium circulation means after generating of power by the fuel cell has stopped, (iv) continuing to circulate the first heating medium in the cooling circulation system through the fuel cell and the heat exchanger, which has been closed, until operation of the first heating-medium circulation means is stopped, and (v) circulating the second heating medium, while the step (iv) continues to circulate the first heating medium, by operating the second heating-medium circulation means so that the second heating medium recovers the heat, which is retained by the first heating medium, via the heat exchanger.