Industrial Gas Turbine Performance Uprates: Tips, Tricks, and Traps

After industrial gas turbines have been in production for some amount of time, there is often an opportunity to improve or uprate the engine's output power, cycle efficiency, or both. Typically, the manufacturer would like to provide these uprates without compromising the proven reliability and durability of the product. Further, the manufacturer would like the development of this uprate to be low cost, low risk, and result in an improvement in customer value over that of the original design. This paper describes several options available for enhancing the performance of an existing industrial gas turbine engine, and discusses the implications for each option. Advantages and disadvantages of each option are given along with considerations that should be taken into account in selecting one option over another. Specific options discussed include dimensional scaling, improving component efficiencies, increasing massflow compressor zero staging, increasing firing temperature (thermal uprate), adding a recuperator, increasing cycle pressure ratio, and converting to a single shaft design. The implications on output power, cycle efficiency, off-design performance engine life or time between overhaul (TBO), engine cost, development time and cost, auxiliary requirements, and product support issues are discussed. Several examples are provided where these options have been successfully implemented in industrial gas turbine engines.