NO Emission Control during the Decoupling Combustion of Industrial Biomass Wastes with a High Nitrogen Content

Most industrial biomass wastes (IBW) are of high nitrogen content and likely to release high levels of NOx during the thermal utilization process. In the present study, two typical IBWs (sewage sludge and mycelia wastes) with a high nitrogen content were chosen as fuels to investigate the feasibility of applying a new combustion technology known as decoupling combustion (DC) to control NO emissions from the combustion of high nitrogen content LBW. A small-scale quartz dual-bed reactor was used to simulate DC, in which the combustion process was separated into pyrolysis gas and char combustion, and the pyrolysis gas was burned out when passing through the burning-char bed. The results indicated that except for one type of mycylial waste sample, DC could greatly reduce the NO emissions for other biomass wastes at a higher temperature (above 873 K) with an O-2-fuel ratio of less than 11 L/g as compared to conventional combustion (CC). A high combustion temperature favored NO reduction in DC before the optimum temperature for NO reduction was reached. Moreover, the effects of the gas velocity and O-2-fuel ratio on NO emissions and the reduction in DC were also discussed, and the results demonstrated that DC presented good stability versus the operating conditions.