An Optimal Maintenance Policy for Compressor of a Gas Turbine Power Plant

Abstract

This paper proposes a condition based maintenance policy for compressors of industrial gas turbine. Compressor blade fouling contributes a major performance loss in the operation of gas turbine. Water washing is usually done for recovery of the blade fouling problem. There exist two different washing methods, namely, online and offline washings. Many researchers suggested that performing a combined program of regular online washing plus periodic offline washing would give fruitful results with respect to economy. However, such studies are of empirical nature or have considered only deterministic treatment. Considering the rate of fouling as discrete state random process, we propose a condition based maintenance policy with periodic online washing and inspection directed offline washing. According to this policy, the compressor undergoes regular online washes for every 1∕λm operating hours, and also undergoes inspections at constant rate λI. If the observed condition at an inspection is worse than threshold deterioration state, then perform offline washing. Otherwise, continue with online washing. The proposed algorithm gives optimum schedules for both online washing and inspections considering minimization of total cost per operating hour as objective. It also gives optimum threshold deterioration level for performing offline washing. A comparison of the results for a hypothetical gas turbine compressor is presented as illustration.