A population balance model of sulphur uptake by Ca-based sorbents in fluidized bed combustors

This paper presents a population balance model aiming at the prediction of sorbent inventory and particle size distribution establishing at steady state in the bed of an air-blown circulating fluidized bed combustor fuelled with a sulphur-bearing solid fuel. The core of the model is represented by population balance equations on sorbent particles which embody terms expressing the extent/rate of sorbent attrition/fragmentation. The effect of the progress of sulphation on attrition and fragmentation is taken into account by selection of appropriate constitutive equations. Model results are presented and discussed with the aim of clarifying the influence of particle attrition/fragmentation on sorbent inventory and particle size distribution, partitioning of sorbent between fly and bottom ash, sulphur capture efficiency. A sensitivity analysis is carried out with reference to relevant operational parameters of the combustor.