Reduction of pulverized coal boiler's emissions through ReEngineered Feedstock™ co-combustion

This paper presents an experimental study of ReEF™ co-firing with coal in a pilot-scale PCB (pulverized coal boiler). ReEF™, or ReEngineered Feedstock™, is a novel fuel composed of both waste and alkaline sorbent, combining therefore the PCB emission control techniques of waste derived fuel co-firing and that of sorbent blending. The results show that ReEF™ co-firing resulted in a higher sorbent utilization and a higher sulfur emissions reduction than sorbent alone. Several combinations of calcium-based and sodium-based sorbents were tested at different stoichiometric ratios. Emissions of SO2, NOx and HCl at different feed compositions, furnace temperatures and air injection patterns were measured. SO2 emission reductions of up to 55% were observed during experiments at gas residence time 4 times lower than that of pulverized coal boiler. The slagging propensity of the ashes in the reactor was also studied. Finally, a model was developed that satisfactorily predicted the experimental SO2 emissions. It was further applied to conditions typical of existing PCB.