Dynamic Model of a Circulating Fluidized Bed Boiler

A dynamic model for a solid fuel fired circulating fluidized bed boiler (CFB) is presented. The model consists of the air-flue gas and the water-steam systems combined together. The Air-flue gas system includes a furnace model describing combustion in a circulating fluidized bed and a convection section describing heat transfer from hot flue gases to super heaters and preheaters. The water-steam system model describes evaporation and superheating. The furnace model includes fuel quality parameters so that the effects of moisture, particle size, heat value, attrition rate, and the amount of volatiles can be simulated. The model is based on the first principles mass, energy, and momentum balances and experimental correlations about reaction kinetics and heat transfer. The model is tested against measured process data. The validation showed that the model can describe the dynamics and static gains of the process very well.