Reactivation of FBC Ash as Sulphur Sorbent: Hydration and Sulphation Studies

The efficiency of limestone utilization for in situ sulphur capture in fluidized bed combustors is low due to incomplete sulphation of CaO. Reutilization of the partially sulphated limestone sorbent for SO₂ emission control is highly desirable both on economic and environmental grounds. Hydration of the FBC ash can reactivate the spent limestone so that the hydrated ash will take up SO₂ effectively when reinjected into the combustors as SO₂ sorbent. In this work hydration of ashes from a large fluidized bed combustor was studied with special focus on the hydration rate. Factors, which affect the rate and efficiency of the reactivation process, such as temperature, particle size, and hydration time, were examined and the effect of hydration on sulphation was also discussed.