Off Design Performance Prediction of Steam Turbines

Abstract

Steam turbines in coal fired power plants are designed for some fixed operating conditions. When operated at those fixed conditions, the turbines are supposed to give maximum cycle efficiency. But off-design conditions occur several times due to condenser variation, environmental change, plant aging, etc. Performance at those off-design conditions affects economy of operation. Hence prediction of performance at off-design conditions is necessary. In this work a 210 MW steam turbine is designed using available design data. Calculated data matched available data quite satisfactorily. Design condition heat cycle data and other available technical data were used for design. Three off-design conditions, varying steam flow rate, varying condenser pressure, and varying inlet steam parameters were considered for study of off-design performance. These effects were suitably incorporated to recalculate performance of the same turbine at these conditions. Performance characteristics are obtained by varying one off-design condition at a time. Specific examples also are solved by simultaneously considering all three mentioned off-design variables using actual field data. Off-design performance predictions were found to be satisfactory.