Modified bottoming cycle for cooling inlet air to a gas turbine combined cycle plant

Abstract

A method for improving the overall power rating and thermodynamic efficiency of a steam and gas turbine combined cycle plant having a conventional heat recovery steam generator (“HRSG”) as part of the bottoming cycle by cooling the inlet air to the gas turbine (particularly under circumstances when the ambient inlet air temperature to the gas turbine exceeds about 60° F.) using an external chiller subsystem. The preferred method includes the steps of initially heating a multi-component working fluid consisting of higher and lower boiling components (such as ammonia and water) by exposing the working fluid to the gas turbine combustion gases inside the HRSG, evaporating part of the working fluid to generate a vapor fraction enriched in the lower boiling point component, separating the enriched vapor fraction from the multi-component working fluid in a vapor-liquid separator, condensing the vapor into an enriched liquid, subcooling a portion of the enriched liquid, and then cooling the inlet air to the gas turbine through heat exchange with a portion of the subcooled and enriched liquid.