Fluidized bed combustion kinetics of spent Nagoorin carbonaceous oil shale

Abstract

The combustion kinetics of Nagoorin carbonaceous spent shale, prepared by Fischer assay, have been measured using a fluidized bed batch technique at 600–700 °C bed temperature. The kinetics were shown to conform to a reaction-controlled, shrinking-core model. The burnout time of a particle in the bed was almost independent of bulk bed temperature. The overall chemical reaction rate constant was only slightly dependent on bulk bed temperature, with a maximum for particles with a diameter close to the bulk bed size, the rate constant reducing for both smaller and larger particles. It was concluded that the particle combustion temperature was also almost independent of bulk bed temperature. An empirical equation was derived to calculate the burnout time for a given particle size between 600 and 700 °C thus enabling the estimation of the time for combustion of a particle to a given burnup.