Uncontrolled Pollutant Emissions from Biomass Combustion Under Simulation Boiler Furnace Conditions

Uncontrolled NOx, S02, CO, and total hydrocarbon emission factors were determined for five types of biomass fuels burned in a laboratory furnace a t varying stoichiometry without combustion air staging. The finely divided fuels were burned in a down-flow, electrically heated furnace under conditions simulating in part the furnace conditions in commercially operating biomass-fueled power plants. Fuel nitrogen and sulfur concentrations ranged from 0.1 - 1.3% and 0.01 - 0.39% by weight, respectively. NOx emissions were observed to decline as equivalence ratio was increased from about 0.3 to 1. S02 emissions were observed to increase over the same range. CO and total hydrocarbon emissions increased sharply for most fuels beginning a t about 0.7 equivalence ratio. Fuel N conversion to NOx was not determined, but the majority of the NOx is thought to derive from fuel-bound nitrogen under the conditions maintained in the furnace. Generally, total uncontrolled NOx production at similar fuel N concentration appeared to be reduced with the biomass fuels compared to coal, but the trend is only weakly supported because of the limited available data.