Determining compressor wash programmes for fouled gas turbines

Abstract

An assessment on the impact of compressor fouling over gas turbine thermodynamic and economic performance is presented. This operational problem is dependent on engine location as it is caused by airborne particles dragged into the engine by the compressor. For the most hazardous locations, performance deterioration can reach 10 per cent/month for power and 5 per cent/month for efficiency, with respect to rated values. Engine washing is required to compensate for these losses. Different approaches made by relevant authors in the past are analysed, showing big contradictions in predicting sensitivity to fouling of engines with different sizes and specifications. This adds complexity to establishing washing programmes based on engine specifications rather than engine location. The conclusion is that a tailored washing schedule must be developed through a trial and error methodology, which is very dependent on the operator's experience with similar engines. These concepts are applied to evaluate the performance of a running engine with severe fouling. The impact of hourly variation of electricity price and length of washing on the cashflow of a plant incorporating compressor is assessed, along with an evaluation of the effect of adopting a washing schedule which is far from the optimal or close to it.