EXPERIMENTAL INVESTIGATION ON IMPROVING THE CALCIUM CONVERSION RATE OF ABSORBENT BY STEAM

The Calcium-based (Ca-based) spent absorbent was reactivated by steam at the temperature of 150 - 600℃ using the laboratory-scale fluidized bed. The effect of steam reactivation on the conversion was studied according to the weight gain after steam absorption and the second sulphation process. The mechanism of steam reactivation was discussed according to the results of composite analysis and the data of XRD (X-ray diffraction). It was found that under the conditions of this experiment, absorbent weight change during the second sulphation process is the comprehensive process of dehydration and sulphation, steam reactivation can increase the conversion of absorbent and the capacity to capture SO2; at lower temperatures, the enhanced CaO utilization is ascribed to the formation of Ca(OH)2 after reactivation; the steam temperature had effect on the absorbent's physical adsorption of steam which is the reason of conversion increase at higher temperatures; there was probably an optimum reactivation time corresponding to a maximum conversion.