Heat transfer mechanisms in steam turbines during warm-keeping operation

A gentle warm-keeping of steam turbines enables a significant reduction of the start time of thermal power plants. As a result, the residual load can be generated more flexibly and resources can be used more sustainably. Keeping a steam turbine warm for extended periods of power plant standstill avoids high thermal stresses during a subsequent conventional start-up process, which also reduces the lifetime consumption of heavily loaded components. In this thesis, heat transfer mechanisms during steam turbine warm-keeping were investigated. Such a warm-keeping process with air differs significantly from conventional steam operation. Therefore, the aim of this work was to develop an accurate and efficient calculation model with which the thermal state of a steam turbine can be predicted and improved. A warm-keeping scenario with varying operating parameters was investigated in detail based on the calculation model developed. The results show that the thermal state and the temperature distribution of the steam turbine can be controlled as required. Thus, steam turbines can be kept at hot start conditions for any period of time and contribute to an improved grid stability and reduced emissions.