Gas Turbine Degradation
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There is a strong incentive for gas turbine operators to minimize and control performance degradation, as this directly affects profitability. The area of gas turbine recoverable and non-recoverable performance degradation will be comprehensively treated in this tutorial. Deterioration mechanisms including compressor and turbine fouling, erosion, increased clearances, and seal distress will be covered along with their manifestations, rules of thumb, and mitigation approaches. The treatment will deal with simple cycle gas turbines in power generation and mechanical drive applications and will also address the impact of performance deterioration on combined and cogeneration cycles. The goal of this tutorial is to provide a nonmathematical treatment of performance deterioration to help plant operators grasp the underlying causes, effects, and measurement of gas turbine performance degradation. Topics covered will include fouling, effect of blade surface roughness, erosion, corrosion, losses of ancillary systems (inlet/ outlet), clearances effects, and the impact of fuels on GT combustion and degradation. To understand the impact of degradation, basic concepts of gas turbine matching and off design operation will be addressed first. The three major sources of performance deterioration will be discussed: Recoverable Deterioration- can be removed by actions during operation of the gas turbine; Unrecoverable Deterioration- can be recovered by an overhaul but not during operation; Permanent Deterioration- residual deterioration present even after a major overhaul. Control aspects and their interaction with performance deterioration mechanisms will also be covered. Lastly, condition monitoring approaches focused on the detection of deterioration will be reviewed.
Kurz, Rainer; Brun, Klaus; Meher-Homji, Cyrus (2014). Gas Turbine Degradation. Texas A&M University. Turbomachinery Laboratories. Available electronically from