Large Eddy Simulation and CO Prediction of Reheat Burner Switch-Off Concept

The reduction of the Minimum Environmental Load (MEL) is a key requirement for increased operational flexibility of Combined Cycle Power Plants (CCPP). In reheat combustors, the MEL is in general limited by CO emissions. The sequential combustion system used in Alstom GT24/GT26 gas turbines [1, 2] offers a unique operation concept, namely Low Part Load operation concept with switched off SEV burner (LPL). This concept is able to significantly reduce CO and thus MEL. Details of the CO formation mechanisms for this concept are analyzed via unsteady CFD calculations. These results are used to predict CO emissions for the full engine. Results are validated against experiments on full engine scale. Field implementation of the LPL concept and validation experience collected during long term commercial operation is described in a separate paper [4].