Improving steam turbine efficiency

This paper describes the condition of a significant number of fossil steam turbines operating in the United States and the maintenance practices used to improve their performance. Through the use of steam path audits conducted by the authors` company and by several utilities, a large data base of information on turbine heat rate, casing efficiency, and maintenance practices is available to help the power generation industry understand how different maintenance practices and steam path damage impact turbine performance. The data base reveals that turbine cycle heat rate is typically 5.23% poorer than design just prior to major outages. The degraded condition of steam turbines presents an opportunity for utilities to improve heat rate and reduce emissions without increasing fuel costs. The paper describes what losses typically contribute to the 5.23% heat rate degradation and how utilities can recover steam turbine performance through maintenance actions aimed at improving steam path efficiency.