Combined cycle system for optimizing cycle efficiency having varying sulfur content fuels

摘要

This disclosure is directed toward combined cycle power plants which include at least one gas turbine and one steam turbine thermally coupled through a heat recovery steam generator (HRSG). Exhaust gas from the gas turbine is used to heat feedwater into steam for the steam turbine. One optimum criterion is to design the HRSG so that the exit temperature of the exhaust gas is at a minimum without the occurrence of sulfur condensation on the economizer tube bundles. The allowable minimum temperature varies with the sulfur content of the fuel and, hence, it would be desirable to be able to adjust the tube surface temperature as necessary in accordance with the sulfur content of the gas turbine fuel.