Dry scrubbing of gaseous HCl and SO2 with hydrated lime in entrained mixing reactor

Abstract

The simultaneous dry scrubbing of gaseous HCl and SO2 by hydrated lime in the entrained mixing reactor has been studied at condition of simulating waste incineration flue gas. The entrained mixing reactor combining a numerical optimized entrained mixing up flow reactor with a rectifier for homogeneous flue gas mixing flow distribution were developed as reaction chambers for the dry scrubbing of gaseous HCl and SO2 with hydrated lime powders. The dry scrubbing performance of this technology was experimented at the pilot scale entrained mixing reactor with 0.3 m in diameter of lower part chamber, 1.29 m in diameter of upper part chamber and 6.0 m in total height. Three kind of hydrated lime powders with different surface area and pore volume were injected with carrier compressed air into the reaction chamber for absorption of acid gaseous. The experimental conditions were the following: reaction temperature 180 °C, gas flow rate 1800Nm3/h and HCl and SO2 concentration in inlet gas 250 ppm, respectively, giving different values for the ratio the amount of fresh hydrated lime and acid gaseous concentration at the inlet of reaction chamber and that corresponding to the stoichiometric molar ratio (SR). The gaseous HCl and SO2 removal efficiencies ranged from 89 to 99% and 87 to 99% respectively. The best performance of dry scrubbing was obtained for high surface area and pore volume of the hydrated lime. Increased the surface area and pore volume of hydrated lime improved the removal performance of the gaseous HCl and SO2 as well as the solid reactant conversion. The concentration of HCl and SO2 at the downstream of bag filter was measured to predict the absorption of gaseous HCl and SO2 on the surface of bag filter.