A SULFUR CAPTURE MODEL FOR CIRCULATING FLUIDIZED-BED BOILERS

A sulphur capture model is presented that incorporates detailed labora tory data of limestone reactivity together with boiler data of particl e-size distribution as well as residence times for the various particl e sizes. The reactivity of limestone as a function of conversion is de scribed by an exponential decay approximation and a total of four cons tants are used to describe the rate as a function of particle size and conversion. The residence time for the different particle sizes and t he particle-size distribution are determined from data of three utilit y circulating fluidized-bed boilers (CFBB) with thermal outputs of 12, 40, and 165 MW. The model was validated by sulphur and calcium analys is of sieved fly-ash and bed-ash samples whereby the degree of sorbent conversion as a function of particle size was determined. (C) 1998 Pu blished by Elsevier Science Ltd. All rights reserved.