THE INFLUENCE OF HCL ON SO2 ABSORPTION IN THE SPRAY DRY SCRUBBING PROCESS

摘要

To examine the influence of HCl on SO2 removal in the spray dry scrubbing process,rnpreliminary experiments on the effect of adding CaCl2 to the lime slurry on SO2rnabsorption efficiency were performed in a laboratory scale spray dryer. It was foundrnthat the SO2 removal efficiency is augmented at CaCl2 concentrations up to 1.2 g/l inrnthe lime slurry. This is ascribed to the influence of the prolonged drying process.rnHowever, SO2 absorption efficiency can not be improved further at higher CaCl2rnconcentrations. A simple estimation shows that this cannot be ascribed solely to therninfluence of the drying behavior of the droplets and more complex explanations have tornbe found. Subsequently, experiments on the simultaneous absorption of SO2 and HClrnwere performed. It was found that the SO2 removal efficiency is enhanced at low HClrnconcentrations in the flue gas. This is ascribed to the formation of CaCl2 in the droplets,rnresulting in a prolonged drying process. After reaching a maximum the SO2 removalrnefficiency falls again at higher HCl concentrations. This can be explained with therncompeting absorption process in which HCl is thermodynamically favored.