On dynamic modeling of industrial gas turbines based on low calorific value (LCV) gaseous fuels

Global energy demand is expected to increase in the following two decades. Operational flexibility of power generation systems is a key aspect when assessing potential solutions seeking to help meeting this expected increase in global energy demand. In low calorific value (LCV) gaseous fuels-fired power plants, it is paramount to consider the effects of the employed LCV/lean-gases-based fuels on the associated gas turbine systems and surrounding equipment. Moreover, because of the industrial processes usually occurring upstream these power plants, the fuel supply conditions change significantly during their normal operation. Gas turbines based on LCV gaseous fuels thus present a quite distinct engine behavior, and their modeling is therefore challenging. The dynamic modeling of such engines is the main focus of this work. Accordingly, the gas turbine dynamic model developed here is initially discussed, along with topics, such as gas turbine mass flow rates, cooling systems effectiveness and gas turbine component characteristics, relevant to the dynamic modeling of LCV fuels-based power plants. The use of the developed model for the simulation of an actual combined cycle power plant with cogeneration based on a LCV fuel is next highlighted. The main results show that overall acceptable agreements between computed parameters and actual power plant operating data are obtained. The corresponding average discrepancies range from 1 to 6%. In spite of the large number of factors directly influencing the numerical results obtained from the real-time simulations carried out, the power plant operating data trends are in general well reproduced by the computed results. The obtained results highlight in particular both the model applicability to operating scenarios presenting significant gradients in gas turbine characteristic parameters, and the need of including in the modeling key processes present in power plants actual operation.