Results of the first application of the SwirlFlash™ wet compression system on a 150mw heavy-duty gas turbine

In general, the compressor takes approximately 2/3 of the expansion work delivered by the turbine. Any reduction of compressor work would improve the power output of the gas turbine. One way of doing this is to inject an amount of water in the inlet air. The amount of water that can be absorbed by the air is limited due to the relative humidity. The SwirlFlash(TM) system of Alpha Power Systems is an over-spray injection system, which delivers an over-saturated mixture to the compressor. Adiabatic compression will heat up the mixture and the water will evaporate inside the compressor. The heat required for evaporation will cool down the air, which results in a lower compressor discharge temperature. This lower discharge temperature leads to a reduction of compressor work. The lower compressor work and the increased fuel flow will raise the gas turbine power output. This paper is the result of the evaluation of the SwirlFlash(TM) System installed at the Herdersbrug power plant of Electrabel Belgium. The wet compression system was commissioned in 2003. In this paper, the principle of the wet compression system and the Herdersbrug installation are described as well as the influence of this system on several parameters such as the compressor discharge temperature, the gas flow, the steam production, the power gain and the heat rate, The influence on the emissions, humming and the interference with anti-icing are also discussed. Finally, the material related aspects and the vibration behavior are treated.