Evaluation of sorbents and additives for dry SO₂ removal

Abstract

Abstract Bench scale studies of the reaction between sulfur dioxide and alkaline sorbents were performed in an integrated fixed bed reactor at low temperature, simulating the fabric filter dust layer of dry FGD systems with SO 2 laden gas passing through it. Three major groups of sorbent were tested: calcitic and dolomitic hydrated lime, sodium bicarbonate, and limestone (calcite aragonite) with salt additives such as CaCl 2 , Ca(NO 3 ) 2 , and NaNO 3 . Relative humidity significantly affected SO 2 absorption by lime and limestone plus additives, but had less impact on NaHCO 3 reactivity. Different reaction patterns for various sorbents were observed: the SO 2 /hydrated lime reaction rate was reduced with conversion of the sorbent, resulting in limited lime utilization, whereas the reactions between SO 2 and NaHCO 3 and SO 2 and CaCO 3 plus additives seem to proceed a constant rate, potentially leading to high sorbent utilizations. Results are discussed relating to sorbent screening for dry FGD systems.