Abstract:
This research studied the emission of NOx and N₂O in circulating fluidized bed combustor for co-combustion of coal and biomass. The sub-bituminous coal and various types of biomass; palm shell, coconut shell, rice husk and sawdust, were used in co-combustion. The riser had a diameter of 10 cm. and its height was 3.0 m. The influence of biomass types, various ratios of biomass to coal ranging from 0 to 70 wt % and secondary air position feeding were studied. Effect of CaO addition on the emission of NOx and N₂O was also investigated. The results showed that the combustion of coal and palm shell gave higher temperature than the combustions of coconut shell, rice husk and sawdust, due to the heating values of this biomass. An increase in mass ratio of biomass and coal was observed to decrease concentration of NOx and N₂O. Feeding secondary air position at 1 m caused the highest amound of NOx and N₂O emission. Furthermore, it was found that the addition of CaO resulted in an increase in NOx emission but a slightly decrease in N₂O emission. The results of this study suggested that co-combustion of coal and biomass could induce more NOx emission compared to N₂O emission.