A METHOD OF EVALUATING LIMESTONE REACTIVITY WITH SO2 UNDER FLUIDIZED-BED COMBUSTION CONDITIONS

The reactivity of limestone with sulphur dioxide has been evaluated du ring conditions similar to those existing in a fluidized bed combustor using a fixed-bed quartz reactor. The reactivity of up to 11 particle sizes of 2 limestones were evaluated, and an exponential decay functi on was found to best describe the rate behaviour versus conversion of CaO to CaSO4. The two constants in the exponential decay approximation could both be expressed as functions of particle size. Subsequently, the limestone reactivity as a function of both size and conversion cou ld be reasonably well described by a total of 4 to 6 constants. An ana lytical sulphur capture model for fluidized bed boilers (FBB) that inc orporates this type of reactivity function is proposed.