Energy & Fuels, Vol.21, No.6, 3709-3717, 2007
A fluidized bed combustion model with discretized population balance. 2. Experimental studies and model validation
The fluidized bed combustion behavior of a Dutch fuel, demolition wood, is of practical interest because of its commercial use for heat generation purposes and has been analyzed by experimental techniques. Experiments with a steady state bubbling fluidized bed combustion boiler at a thermal input scale of 1 MWth were carried out. The effect of different operating parameters (fluidization velocity, bed temperature, etc.) and air-staging (secondary air injection) on gaseous emissions (CO and NO) has been studied. The intention is to increase the use of this type of boiler especially for greenhouse heating, making use of the available residues. One of the unique features of this boiler is a moveable internal heat exchanger, which makes it possible to run it at variable thermal outputs. Experimental data was further analyzed and compared with the simulation results carried out with the fluidized bed model especially developed for solid fuel feedings. The model takes into account devolatilization, fragmentation, and attrition of the solid phase together with heterogeneous and homogenous reactions. A particle size distribution model is also included to calculate the elutriation losses of fine char particles. Experimental and model results indicate that optimization of operating parameters and air-staging ratios can significantly reduce the gaseous emissions.