Effect of various inlet air cooling methods on gas turbine performance

Turbine air inlet cooling is one of many available commercial methods to improve the efficiency of an existing gas turbine. The method has various configurations which could be utilized for almost all installed gas turbines. This paper presents a comparison between two commons and one novel inlet air cooling method using turbo-expanders to improve performance of a gas turbine located at the Khangiran refinery in Iran. These methods have been applied to one of the refinery gas turbines located at the Khangiran refinery in Iran. Two common air cooling methods use evaporative media or a mechanical chiller. The idea behind the novel method is to utilize the potential cooling and power capacity of the refinery natural gas pressure drop station by replacing throttling valves with a turbo-expander. The study is part of a comprehensive program with the goal of enhancing gas turbine performance at the Khangiran gas refinery. Based on the results, it is found that using turbo-expanders is the most economically feasible option and so is recommended to be utilized for improving gas turbine performance at the Khangiran refinery.

Research highlights
► 3 inlet air cooling methods to improve performance of a gas turbine are studied.
► Evaporative media, EM, mechanical chiller, MC, and turbo-expander, TE, are the methods.
► The idea of TE is to utilize cooling and power capacity of the natural gas pressure drop station by a TE.
► The efficiency enhancement in MC, EM and TE systems are 5%, 3% and 4% respectively.
► The payback period for TE method is lower than the other methods.