Towards the modelling and control of NOx emission in a fluidized bed sludge combustor

Sludge incineration is a widely used technology because of its large volume reduction and complete organic destruction. However, incineration does encounter a number of drawbacks, among which are notably carbon monoxide (CO) and nitrogen oxides (NOx) emissions. Carbon monoxide emissions are efficiently avoided by oxygen regulation in the furnace. Nitrogen oxide (NOx) formation, however, is very complex and not well known. This paper proposes a dynamic model of sludge combustion in an industrial fluidized bed combustor mainly focused on NOx formation. The model is tuned with industrial data. A control strategy is proposed to improve on the current industrial regulation, simultaneously ensuring CO and NOx control, yet without decreasing the combustion efficiency. The results are sufficiently acceptable for this process to be carried out in a real incinerator plant.