Combined gas and steam cycles - A thermodynamic analysis at full load and part load

摘要

This report deals with the combined gas and steam cycle. The main topics are full load and part load simulations of the combined cycle. Special focus has been put upon the simulation of the heat recovery steam generator. The author has chosen to examine the influence of the gas side pressure drop in the heat recovery steam generator on the combined cycle performance, for full load and part load simulations. The calculations of the combined cycle in this study are based on a model where the inlet gas velocity into the heat recovery steam generator is used as a design parameter. The importance of the method used in the study is of special interest at part load operation of the combined cycle. Three different gas turbine part load regulation systems are studied, inlet guide vane regulation, mass fuel rate regulation and one regulation system where one or several topping gas turbines, of a set of gas turbines, are shut down. The simulations of the gas turbine cycle are based on a model using entropy calculations. This report shows some new equations for a cooled turbine expressed in the same terms as an uncooled turbine. Results from different assumptions made on the gas turbine cooling model are shown. The radiative part of the heat transfer in the heat recovery steam generator is studied. (ERA citation 19:032998)