Improving combined cycle power plant performance in arid regions

Abstract

Paper presented at the 6th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, South Africa, 30 June - 2 July, 2008.

In arid regions, where cooling water supplies are limited and highly regulated, combined cycle power plants (CCPPs) are turning to air-cooled condensers instead of water-cooled condensers. However, performance of air-cooled condensers can decline as ambient temperatures increase and result in loss of steam turbine power output. At the same time, as ambient temperature rises, net output of the gas turbine also can decline due to increased power consumption by the compressor and reduced power output by the gas turbine. In this paper, it is proposed to remedy these problems by pre-cooling the inlet air to the air-cooled condenser as well as the compressor, using a low-temperature thermal energy storage (TES) system. The TES is maintained around 5ºC by an absorption refrigeration system driven by the waste heat in the stack gases. A thermodynamic analysis of a 500-MW CCPP incorporating the above concept is presented.