Feasibility of using red mud as bed material for treating N2O in fluidized bed combustion

•The use of red mud to reduce N2O produced in combustion was proposed.•Coal-fired experiments were conducted to explore the effects of red mud on N2O.•Red mud can reduce the original N2O emission in the bubbling bed.•Red mud can remove N2O in the flue gas of fluidized bed combustion.•CO enhances the N2O and NO reduction performance of red mud. Red mud, a type of industrial waste, currently can’t be utilized effectively, and there are no efficient methods for controlling N2O emissions in circulating fluidized bed (CFB) boilers. Based on characteristics of N2O and the components of the red mud, the red mud was used in this study as bed materials of fluidized bed to treat N2O produced by coal combustion. The decomposition effect of red mud on N2O under various operating conditions during the coal combustion process was quantified in a bubbling fluidized bed, and the decomposition of N2O and NO after the flue gas passed through the bed material was investigated. In a variety of operational conditions, the presence of red mud has been observed to exert a pronounced inhibitory effect on the formation of N2O, while concurrently exhibiting the capacity to diminish the nitrogen conversion rate of N2O to varying degrees. Comparative analysis of N2O and NO emissions from char and coal revealed different levels of reduction, with the combination of CO and red mud being the most effective method. Red mud demonstrated superior N2O removal capabilities, while CO was more effective for NO removal. The issue of increasing NO can be resolved by balancing the iron-aluminum ratio of red mud, allowing the flue gas to pass through the red mud in the CFB’s low-temperature zone, and focusing on N2O removal in the furnace.