Part-load versus downrated industrial gas turbine performance

Abstract

For distributed power generation, sometimes the available gas turbines cannot match the power demands. It has been usual to uprate an existing gas turbine in the lower power range by increasing the firing temperature and speeding it up. The development costs are high and the time to make it operational is large. In the other hand, de-rating an existing gas turbine in the upper power range may be more convenient since it is expected to cut significantly the time for development and costs. In addition, the experience achieved with this engine may be easily extrapolated to the new engine. This paper deals with the performance analysis of an existing gas turbine, in the range of 25 MW, de-rated to the range of 18 MW, concerning the compressor modifications that could be more easily implemented. Analysis is performed for the base engine, running at part-load of 18 MW. A variable geometry compressor is derived from the existing one. Search for optimized performance is carried out for new firing temperatures. A variable geometry turbine analysis is performed for new NGV settings, aiming at better cycle performance.

Keywords