Theoretical analysis of combustion and gasification of various fuels in fluidized bed systems

Modern power plant concepts including fluidized bed technology offer high efficiency and low emissions for combustion and gasification of coals, biomass and wastes. The design of new power plants and the optimisation of existing processes is more often supported by applying mathematical models. The mathematical model for fluidized bed systems which has been developed at the Institut fur Energietechnik, Universtat Siegen, allows the simulation of steady state or dynamic operation behaviour, the examination of the interactions between the components of the overall plant, e.g. a complete combined cycle power plant, as well as a detailed investigation of various components. In this paper the influence of different fuels on the operation behaviour of combined cycle power plants based on pressurized circulating fluidized bed combustion and of fluidized bed gasification reactors is described applying the presented simulation model. In case of pressurized circulating fluidized bed combustion the effects of fuel variation including variation of coal type and moisture content on emissions and on process reaction of water/steam cycle and on gas turbine is analysed. The submodel for bubbling fluidized bed reactors is used to simulate the air/steam gas fraction of brown coal, peat and sawdust. The influence of fuel type and operating parameters on the product gas quality is discussed in detail.