Abstract

OGENGA, D. O.; SIAGI, Z. O.; ONYANGO, M.S.  and  MBARAWA, M.. An Overview of the Use of Ca(OH)₂/Fly Ash in Flue Gas Desulphurization. R&D j. (Matieland, Online) [online]. 2008, vol.24, pp.4-8. ISSN 2309-8988.

Most of the SO₂ emission removal techniques have been based on the use of calcium-based materials. For instance, limestone has been used in the wet scrubbing while lime in the dry flue gas desulphurization (FGD) processes. Recent research efforts have prioritized on the semi-dry and dry FGD whose major sorbent, hydrated lime faces the problem of low utilization. Improving sorbent utilization thus posses a challenge in the dry FGD processes. Sorbents obtained by conditioning of lime with different sources of silica lead to a significantly higher calcium conversion compared to those obtained using hydrated lime only. Coal fly ash has a high content of silica and is viable for improving the sorbent utilization. This paper assesses the use of various sorbents and gives an overview of fly ash as one of the conditioners used to improve the sorbent utilization. It further focuses on the hydration process and the conditions that are likely to affect the performance of the resultant conditioned sorbent material during hydration and sulfation processes. The paper further explores the future challenges facing dry and semi-dry FGD processes.

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