Absorption behavior of chlorine and sulfur by Ca(OH)2 under simulated conditions with a fluidized bed combustor

This study was carried out to investigate the absorption reaction of chlorine and sulfur with Ca(OH)2 under simulated conditions related to the co-combustion of refuse-derived fuel and sewage sludge in the fluidized bed combustor, such as high temperature, moisture and a mixing of samples. The combustion experiments were carried out in an electrical furnace with PVC and sulfur powders as the waste samples. High-purity slaked lime powder was used to capture the chlorine and sulfur. The experimental results showed that the removal efficiencies of both chlorine and sulfur were over 90% when the mole ratios of Ca on Cl and S were over 2.5. Furthermore, simultaneous absorption was helpful in improving the removal efficiency of chlorine and sulfur. The presence of chlorine markedly increased the removal efficiency of sulfur. The removal efficiency of chlorine was the highest at 700°C in both independent and simultaneous absorption. The removal efficiency of sulfur increased as the temperature increased, but the removal efficiency of chlorine sharply decreased from 95 to 83% when the moisture content in gases increased from 0 to 20 vol%. These results were confirmed by the combustion test of granular CaCl2.