Ash aerosol particle size distribution, composition, and deposition behavior while co-firing coal and steam-exploded biomass in a 1.5 MWth combustor
Abstract
Five different blends of Utah bituminous coal and steam-exploded pine (100/0, 75/25, 50/50, 25/75, 0/100 by mass) were fired in a 1.5 MWth combustor. Primary objectives were to understand mineral matter behavior by analyzing aerosol size distribution, aerosol size-segregated composition, ash deposition mass, and ash composition. For particle size0.1 μm. During pure biomass combustion, aerosol particles >15 μm contained higher mass fractions of potassium (+126%), calcium (+132%), and iron (+115%) and lower fractions of aluminum (−49%) and silicon (−29%) than pure coal. Ash deposition mass decreased with increasing biomass blends. Downstream ash deposits contained −3% to 55% higher sodium and potassium than the upstream ash, which highlights the dilution effect of the condensation layer by inertial impaction on the upstream side. Submicron ash load and deposited mass for 30-min and 90-min tests showed R2 values of 0.974 and 0.966, indicating that smaller particles' concentration determines the final mass. The results suggest that plant operators should not face any difficulties while co-firing these blends with respect to ash deposition by fouling.