Modelling sorbent conversion and attrition during fluidized bed calcium looping

In this paper we present a population balance model on sorbent particles in a dual fluidized bed calcium looping process for CO2 capture. The model is based on material balances on the sorbent as it is recirculated between the calciner and the carbonator. The carbonation step is modelled by assuming a well-stirred behavior in the carbonator with a suitable expression for the rate of CO2 uptake. Sorbent regeneration is modelled under the assumption of extremely fast calcination. Sorbent attrition is also considered to account for modifications in the particle size distribution during both calcination and carbonation, using purposely-derived constitutive expressions validated against results of a parallel experimental campaign. The influence of the relevant process parameters on the degree of particle carbonation, on the CO2 capture efficiency, on the rate of sorbent elutriation, and on the thermal power demand associated with sorbent regeneration in the calciner is assessed.