Evaluating the efficiency of low pressure part of steam turbines based on probing measurements

A methodology oflow pressure part turbine efficiency evaluation based on measurements of the steam flow parameters in the interspaces between neighbouring stages is described. Specially manufactured probes have been applied carry out such measurements. The efficiencies of the stages operating in the superheated steam zone result directly from experimental values of pressures, temperatures, and flow angles. To complete the efficiency evaluation for the stages operating in the wet steam region, a relevant estimation of blading system losses has been proposed and validated. This evaluation of losses is compatible with the measurement results. Adaptation of a comparative error analysis makes it possible to show the advantages of the methodology over the thermal balance applied during performance tests. The low pressure turbine efficiency evaluation methodology has been applied to numerous steam turbine power units of 200–500 MW output.