Volatile-N Behavior in Oxygen Carrier Aided Solid Waste Combustion Using a Two-Stage Fluidized Bed Reactor

Oxygen carrier aided combustion (OCAC) represents an innovative approach to enhancing the efficiency and stability of solid waste combustion. This technology substitutes traditional inert bed materials with metal oxides, which can significantly influence NOx formation during redox processes. This study investigates the in situ and ex situ effects of both reduced and oxidized ilmenite ore (OC) on the conversion of volatile nitrogen (volatile-N) from four different fuels using a two-stage bubbling fluidized bed reactor. Experimental results show that reduced OC can promote the reduction of NO from pyrolysis gas, with reductions of 2.11% for sawdust (SD), 88.23% for torrefied leather (LT), 25.18% for waste tires (WT), and 92.98% for bituminous coal (BC), while the reduced OC increases the formation of HCN and NH3 in pyrolysis process. Oxidized OC can directly oxidize HCN and NH3, leading to an increase in NO by 2.80% for SD, 21.57% for LT, 15.19% for WT, and 9.92% for BC. These patterns were consistent in both in situ and ex situ experiments. This suggests that OCAC technology is most effective at lower oxygen concentrations. Overall, these insights advance our understanding of the potential pathways for volatile-N conversion in solid waste combustion facilitated by OCAC, highlighting critical operational parameters that influence the chemistry of volatile-N in solid waste combustion.