Reactions of acid gases with calcium hydroxide

Abstract

Abstract Sulphur and Chlorine containing fuels form SO2 and HCl during combustion. They have to be removed from the flue gas with means as optimized as possible both economically and technically. In order to do so maximum utilisation of the sorbent is necessary. In this work the removal of SO2 and HCl, by the use of Ca(OH)2 at industrial conditions, is investigated in a laboratory by means of thermo gravimetric analysis, Fourier transform infrared spectroscopy-analysis and offline analysis. The SO2 or HCl uptake by the sorbent is found for different settings with varying relative humidity, temperature and acid concentrations. Especially the removal of HCl by the sorbent at low concentrations is emphasised. A dependency on the relative humidity is found with respect to HCl uptake, as increased relative humidity increases the HCl uptake by the sorbent. It is also found that the HCl concentration plays a role for the uptake. For HCl concentrations of 250 ppm or above the uptake is considerably higher than for HCl concentrations of 50 ppm or below. Indications are found that CaCl2 might be a product from the reaction between HCl and Ca(OH)2.