Panel Bed Filters for Simultaneous Removal of Fly Ash and Sulfur Dioxide

Abstract

Half-calcined dolomite, [CaCO₂ + MgO], is a candidate solid for use in panel bed filters which can simultaneously remove fly ash and S0₂ from flue gas. Unpublished work by Coke, summarized here, showed that good reactivity is obtained at about 600°C, making the device usable in a boiler ahead of the economizer. We have confirmed Coke’s results. Further, we have demonstrated that the solid can be regenerated by reduction of calcium sulfate to calcium sulfide, followed by release of H₂S from the sulfide by its reaction with steam and carbon dioxide. Three absorptions with intermediate regeneration showed no significant loss of reactivity or capacity. A flowsheet example is presented for the cyclic use of half-calcined dolomite in a process producing elemental sulfur for the market.