On-line compressor washing has shown to relatively improve engine performance by decelerating the rate of engine degradation due to fouling during operation. There is a number of influencing parameters that determine the economic benefit, some of which includes the frequency of washing, the effectiveness of washing liquid and the size of the engine or power output produced.
This study, unlike others, explores the cost-benefit analysis, focusing on the viability of compressor washing for various gas turbine engines or rated capacities, ranging from a 5MW single machine to a 300MW unit. Fouling degradation trend obtained from actual machine operation have been implemented and the application of different washing frequencies and recoveries of lost power shows the significantly higher return on investment for the larger engines in comparison to the smaller engines. This is partly due to the fact that the washing equipment cost, though increases with engine size, does not increase proportionally. Another contributing factor is the cost penalty per MW when the same level of degradation is implemented for all the engines.
Some of the key aspects captured in this study are the capital and maintenance cost used, that relates to the different engine sizes, therefore ensuring a more indicative basis for comparing the viability of the different engines. This also includes the estimation of washing liquid utilised based on their respective typical mass flows.
When the number of engines increases to 4 for a given operations, the return on investment increases by a factor of 3.5. This is possible as one wash unit can be applied to more than one engine within proximity. Higher return on investment is achieved when more than one relatively small engine is used to obtain a higher total power output. This is about 1.7 times higher for four 63MW engines versus one 255MW, as relatively cheaper washing equipment is implemented for the same total operational capacity. The study also shows that on-line washing is not always viable for electric power generation. This is observed for smaller light-duty engines, especially in situations when the level of fouling is relatively low.