SULFUR RETENTION BY LIMESTONE PARTICLES UNDER PFBC CONDITIONS

The SO2 retention by limestone in a Pressurized Fluidized Bed Combusto r (PFBC) generally occurs by direct reaction between uncalcined limest one particles and sulphur dioxide. A kinetic study of direct sulphatio n reaction of limestone is presented in this paper. A wide particle si ze range (between 26 and 780 mu m), temperatures from 750 to 900 degre es C and reaction times up to 12 hours were tested. It was found that the reaction was mainly diffusionally controlled. The chemical rate co nstant deduced from the conversion-time data at low conversion degrees (<0.05) was found to be: K-p=10.3910(-3) e(-22900/RT), mol/cm(2) s at m.