Impact of Compressor Flexibility Improvements on Heavy-Duty Gas Turbine for Minimum and Base Load Conditions

Fluctuating consumer energy demand has resulted in the conventional power plant system operating under off-design conditions most of the time. Furthermore, the increasing introduction of renewable energy capacity has increasingly reduced the traditional fossil-fuelled power plant. In order to improve the existing power plant flexibility and the energy surplus or deficit, retrofittable solutions for gas turbine compressors are proposed. Two different operation strategies including variable inlet

guide vanes (IGVs) and blow-off extraction (BO) are illustrated to access the part load and the minimum environmental load performance of gas turbines and power plants systems. A typical 15-stage F-class gas turbine compressor is chosen as the reference one and some energy demand cases are selected to validate the response of the solutions adopted, with different ambient temperatures, ranging from the reference one, at 15°C, to a lower level, at 0°C. The numerical steady state analysis is compared and discussed with an experimental campaign performed by Ansaldo Energia under the framework of the European project Turbo-Reflex in order to identify implementation opportunity in the existing thermal power plant feet. The results show how the proposed 3D CFD model is able to provide reliable performance figures. Additionally, the combined strategies can reduce gas turbine mass flow rate and power plant output, without significantly penalizing the efficiency.