Assessment of Inlet Cooling to Enhance Output of a Fleet of Gas Turbines

An analysis was made to assess the potential enhancement of a fleet of 14 small gas turbines' power output by employing an inlet air cooling scheme at a gas process plant. Various gas turbine (GT) inlet air cooling schemes were reviewed. The inlet fogging scheme was selected for detailed studies due to its low installation capital costs. The results indicate a potential of 10% enhancement in power output on a warm, dry day, a 5% enhancement in a typical summer day, but only a 1% enhancement in a hot humid day. It is shown that the relative humidity is the most important factor that affects the impact of inlet fogging. Therefore, the inlet fogging can enhance GT power output not only in the hot summer, but also in other dry days during the year. An annual analysis was also conducted based on New Orleans's annual weather conditions. The results indicate a potential of increased power of 2.34% with inlet fogging to saturated state and additional 5% increased power with 0.5%(wt.) overspray. The total potential power increase for the gas turbine fleet is 7.39% at $265/HP. Since the gas turbine fleet consists of small units, the installation cost is much higher than a typical cost of $34~60/HP for installing an inlet fogging system on a gas turbine larger than 300MW. However, this installation capital cost is 57% cheaper than buying a new gas turbine, which will cost about $608/HP