Off-Design Analysis of a MCFC-Gas Turbine Hybrid Plant

The paper presents a model for the off-design analysis of a hybrid plant based on a MCFC and a gas-turbine. The model is used to define a possible regulation strategy for the power plant, minimizing the performance decay at partial load and allowing investigation of the interaction issues among the different plant components. The hybrid plant reflects at nominal conditions the expected performances for the 500 kW-class MCFC plant proposed by Ansaldo Fuel Cells. The simulation is carried out respecting the matching of the gas-turbine and the part-load behavior of the fuel cell and the heat exchangers. The gas-turbine is modeled through compressor and turbine performance maps, and the FC is modeled through a finite volume code. The results indicate the possibility to regulate effectively the plant power output acting on the turbine shaft speed, the air-to-fuel ratio, the bypass of cathode air, and the fuel utilization, achieving very high part-load efficiency and respecting constraints on the admitted operating range for the plant components.