Efficient use of recuperation in CHP gas turbine plants designed for flexible operation

摘要

During the last years the economic importance of gas turbines for simultaneous generation of power and steam has risen significantly. The importance of the utilisation of waste heat from the combined process follows this development very quickly. For a given plant, however, the ratio of generated power and the steam quantity varies within very narrow limits only. The heat shifting systems with variable admission of the steam turbine known hitherto only enable an operating mode which is independent in the relatively narrow range of the demand for power and heat. Innovative heat shifting systems (recuperators) can extend the width of this range considerably and increase at the same time the power ratio and the efficiency of the plant. Here, the old recuperation principle becomes relevant again. This innovative technology also presents itself for REKU gas turbines with external firing for the generation of power from fuels depending on process conditions (such as natural gas) Thereby it is basically possible to substitute rare fuels (such as natural gas) for low-caloric waste fuels. This paper shows basic thermodynamic interrelations and possible applications.