Improved fuel conversion through oxygen carrier aided combustion during incineration of biomass-based solid waste in a rotary kiln

Abstract

Solid waste (SW) incineration in a rotary kiln (RK) faces great CO fluctuations due to the batch-fired nature, resulting in incomplete SW combustion, which makes its optimization challenging. A method introducing an oxygen carrier (OC) material into the RK has been first proposed to improve SW conversion, lower the CO emission and reduce the fluctuation of emitted CO during the combustion. In this work, manganese and ilmenite ores have been investigated as OCs, and introduced into a lab-scale RK during the combustion of biomass-based SW. Results show that both the introduction of manganese and ilmenite ores have lowered the CO emission and alleviated the fluctuation of emitted CO under reduced oxygen supply. It has been demonstrated that the OC can increase the available oxygen for effective biomass-based SW combustion in the RK since it can continuously transfer lattice oxygen from the active layer to the passive layer with the bed rolling. Besides, the unconverted CO can be burnt more completely and evenly through the gas–solid redox reaction attributed to the reactivity of OCs over CO. In addition, the OCs can also react with the char through a solid–solid reaction at a high temperature over 1073 K. As a result, the carbon conversion can be increased in the presence of OCs.