Heat recovery method and apparatus in fuel cell system, and fuel cell system including the apparatus

A fuel cell system comprising:

• a fuel processor that reforms a fuel gas into a reformate gas;
• a stack that generates a direct current (DC) using the reformate gas;
• a power converter that converts the DC into an alternating current (AC);
• and
• a heat recovery apparatus comprising:
• a storage tank that stores water heated by the fuel cell system;
• a pump that pumps the water from the storage tank;
• a first heat exchanger that recovers heat from cooling water discharged from the stack;
• a second heat exchanger that recovers heat from an electric heater that uses surplus power generated by the fuel cell system;
• a third heat exchanger that recovers heat from an anode-off gas discharged from the stack and separates liquid from the anode-off gas;
• a fourth heat exchanger that recovers heat from air discharged from the stack;
• a fifth heat exchanger that recovers heat from exhaust gas discharged from the fuel processor;
• an electronic valve that controls water flow to the first heat exchanger;
• a proportionate valve that controls water flow to the second heat exchanger;
• a first thermocouple that measures the temperature of water output from the first heat exchanger;
• a second thermocouple that measures the temperature of water output from the second heat exchanger;
• and
• a third thermocouple that measures the temperature of the third heat exchanger.

A heat recovery method of a fuel cell system comprising a fuel processor, a stack, and a power converter, the heat recovery method comprising:

• determining whether the fuel cell system is completely activated;
• if the fuel cell system is completely activated, closing an electronic valve and completely opening a proportionate valve, in order to control water flow to a second heat exchanger that recovers heat from an electric heater that uses surplus power generated by the fuel cell system;
• supplying cooling water to the stack and opening the electronic valve that controls water flow to a first heat exchanger that recovers heat from the cooling water;
• and
• supplying a predetermined amount of water to the first heat exchanger.