Reaction characteristics of Ca(OH) 2, HCl and SO 2 at low temperature in a spray dryer integrated with a fabric filter

Abstract

The objective of this research was to evaluate the reaction characteristics of Ca(OH) 2, HCl and SO 2 in the flue gas emitted by a laboratory incinerator. The amount of sulfur retained in the residues (including the spray dryer ash and baghouse ash) was also evaluated in this study. The experimental parameters included HCl concentration (500–2000 ppm), SO 2 concentration (500–2000 ppm), relative humidity (40–80% RH), and the addition of CaCl 2 (30 wt.%). The results indicated that an HCl concentration of 500–2000 ppm did not affect HCl removal efficiency in the spray dryer at 150 °C and 45±5% RH. On the other hand, increase in SO 2 concentration from 500 to 2000 ppm enhanced SO 2 removal at 150 °C and 75±5% RH. Moreover, increase in removal efficiency of SO 2 was more obvious when the relative humidity was greater than 80%. When the flue gas contained both HCl and SO 2 simultaneously, the removal efficiency of SO 2 could increase from 56.7 to 90.33% at HCl concentration of 236 ppm. However, when the concentration of HCl exceeded 535 ppm, the removal efficiency of SO 2 decreased with increasing concentration of HCl. The removal efficiency of SO 2 could be increase to 97.7% with the addition of CaCl 2.