Reduction of recycled NO over char during oxy-fuel fluidized bed combustion: Effects of operating parameters

To investigate the effects of operating parameters on the recycled NO reduction over char during oxy-fuel fluidized bed combustion, tests with two types of char were carried out in a bubbling fluidized bed system. The reduction ratios of recycled NO were calculated based on the test results. It was found that char combustion obviously affected the recycled NO reduction in the oxy-fuel fluidized bed combustor. The reduction of recycled NO was promoted by the increase of oxygen concentration in the feeding gas. The reduction ratio of recycled NO could be improved by the higher reaction temperature. Although the smaller sizes of char particles were conducive for char combustion, char particle sizes had little effects on the reduction of recycled NO. The prolonging of gas residence time favored the reduction of recycled NO over char. In addition, the effects of various char types on the recycled NO reduction were also evaluated in this study.