Power generation system, and methods for starting and operating fuel cell in power generation system

A method for starting a fuel cell in a power generation system, comprising the steps of:

• upon the starting of the fuel cell, activating a booster provided before an air electrode of the fuel cell to boost a pressure of a portion of compressed air compressed by a compressor of a gas turbine as well as to circulate the portion of the compressed air from a downstream side to an upstream side of the booster;
• and
• upon at least one of the pressure and a flow rate of the portion of the compressed air compressed by the compressor of the gas turbine reaching a predetermined value, supplying the portion of the compressed air to the air electrode of the fuel cell while boosting the pressure of the portion of the compressed air with the booster, wherein
• the boosting of the pressure is performed while stopping supplying the portion of the compressed air to the fuel cell.

A power generation system comprising:

• a gas turbine having a compressor, a combustor and a turbine;
• a first compressed air supply line supplying a portion of compressed air compressed by the compressor to the combustor;
• a fuel cell having an air electrode and a fuel electrode;
• a second compressed air supply line supplying an other portion of the compressed air compressed by the compressor to the air electrode;
• a booster provided in the second compressed air supply line;
• a pressure control valve provided in the second compressed air supply line;
• a first detector provided on an upstream side of the pressure control valve in the second compressed air supply line, the first detector detecting a first pressure of the other portion of the compressed air supplied to the air electrode;
• a second detector provided on a downstream side of the pressure control valve in the second compressed air supply line, the second detector detecting a second pressure of the other portion of the compressed air supplied to the air electrode;
• a controller controlling an extent of opening of the pressure control valve in response to a fluctuation in the first pressure detected by the first detector and a fluctuation in the second pressure detected by the second detector,
• such that a pressure of the other portion of the compressed air supplied to the air electrode is held constant, in a state where the portion of the compressed air compressed by the compressor is supplied to the combustor via the first compressed air supply line and the turbine starts rotating, and where the other portion of the compressed air is supplied to the air electrode via the second compressed air supply line.

A method for operating a fuel cell in a power generation system, comprising the steps of:

• supplying a portion of a compressed air compressed by a gas turbine to a combustor of the gas turbine;
• supplying an other portion of the compressed air compressed by a compressor of the gas turbine to an air electrode of a fuel cell via a pressure control valve;
• providing a booster in association with the other portion of the compressed air;
• and
• upon (i) a first pressure, on an upstream side of the pressure control valve, of the other portion of the compressed air supplied to the fuel cell fluctuating, and (ii) a second pressure, on a downstream side of the pressure control valve, of the other portion of the compressed air fluctuating, adjusting a flow rate of the other portion of the compressed air such that a pressure of the other portion of the compressed air is held constant.