Gas turbine engines ingest large quantities of air from the surrounding
atmosphere that often contains contaminants of different concentrations
depending on the type of environment, atmospheric condition, seasonal changes,
and wind direction. Deposition of contaminants and build-up on the compressor
blades lead to compressor fouling. On-line and off-line compressor washing have
been shown to relatively improve engine performance by decelerating or
eliminating (in the case of off-line) the rate of engine degradation due to fouling
during operation. There are a number of influencing parameters that determine
the economic benefits of washing, some of which include the frequency of
washing, effectiveness of washing liquid, and the power output produced.
This research explores the cost-benefit analysis for on-line washing from
72hrs to 480hrs frequency, 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 trends obtained from actual
machine operation have been implemented in this study. The application of
different washing frequencies and time-based recoveries of lost power shows a
significantly higher return on investment for the larger engines in comparison to
the smaller engines. This is partly because the washing equipment cost, though
increases with engine size, does not increase proportionally. Some of the key
aspects captured in this study are the capital and maintenance costs used for
washing, relating to the different engine sizes, thus ensuring a more indicative
basis for comparing the viability of the different engines. This also includes the
estimation of washing liquids utilized based on their respective typical mass flows.
The study also presents an economic benefit for off-line washing from
720hrs to 4320hrs, focusing on costs that are related with off-line washing,
specific cost of energy produced and net profit after deducting washing cost for
different engines, related to their rated capacity. The result shows that at higher
losses, off-line or on-line washing should be directly proportional to deposition or
rate of degradation, and as the degradation rate increases, off-line or on-line
washing is more frequent. However, when the degradation rate decreases, off-
line or on-line washing should be less frequent. When off-line and on-line washing
at different combinations are incorporated, the study shows that adopting the
least possible off-line washing case combined with a fair amount of on-line
washing case of 36 times a year provides higher net profit after deducting
washing cost compared to other washing combinations.
The study also presents an optimization method for on-line and off-line
washing capable of evaluating compressor washing performance and economics
using non-dominated sorting genetic algorithms approach. The result shows an
optimum on-line washing frequency ranging from 90hrs to 110hrs for all the
engine sizes at 7.2% power drop except for light-duty engine that was found to
be not viable.PhD in Aerospac