Shape and operation optimisation of a supercritical steam turbine rotor

Abstract

The presented study discusses the problem of shape optimisation of selected areas of the rotor of the high pressure part of an ultra-supercritical steam turbine together with the optimisation of the turbine start-up method, using the maximum stress objective. The analysis relates to the rotor of a conceptual ultra-supercritical turbine which is characterised by high parameters of operation. The consequence is that the machinery components are subjected to significant stress, which further results in a substantial reduction in its life and reliability. These adverse effects can be contained in two ways, i.e. by optimising the shape of the rotor areas characterised by high stress values and by optimising the method of the turbine start-up. In the case of the rotor under analysis, it is the thermal stress caused by large temperature gradients occurring in unsteady states of operation that has a predominant impact on the stress level.The performed research prove that the manner in which the power unit start-up is initiated and carried out depends largely on the limitations of the materials used to make the machinery components. This, in turn, has an impact on the assessment of the power unit in terms of energy and economy. The obtained optimisation results translate directly into the power unit energy effectiveness.