Control of SO_x emissions by in‐furnace sorbent injection: Carbonates vs. hydrates

Enhancement of reactivity in surfactant-modified sorbents for sulfur dioxide control

“…Alternatively, it could be argued that a delay in sintering would allow the sorbent to retain higher specific surface areas and porosities and, therefore, to remain more reactive longer. The relationship of higher calcined surface areas to higher reactivity with S02 is well established (Newton et al, 1985;Harrison et al, 1985;Cole et al, 1985;Beittel et al, 1985;Slaughter et al, 1985;Borgwardt and Bruce, 1986b). Borgwardt and Bruce (1986b) have shown reactivity to vary with square of the specific surface area of the calcined sorbent over the range 2-63 m2/g.…”

Study of Calcium-Based Sorbents for High-Temperature H2S Removal. 3. Comparison of Calcium-Based Sorbents for Coal Gas Desulfurization

“…However, higher temperatures also increase the sintering rate of CaO, especially in the presence of CO2 and H2O, and result in surface area reduction for the sulfur sorbent (Borgwardt, 1989a,b). Hydrated sorbents are more reactive than carbonates (Newton et al, 1986) and dolomites often exhibit better sulfidation and regeneration capability than limestone, probably because the unreactive MgO matrix hinders sintering of CaO and CaS and aids gas diffusion within the solid. This justifies the common use of dolomite rather than limestone, even though MgO, which comprises a substantial fraction of the weight of the sorbent, is inert toward H2S during gasification.…”

Surface area evolution of calcium hydroxide during calcination and sintering

“…More recent work has suggested that calcination, sintering, and sulfation may all occur on the same time scale (Newton and Pershing, 1986;Newton et al, 1985;Mai, 1987). Previous models have not considered that all three processes occur simultaneously.…”

“…Previous models have not considered that all three processes occur simultaneously. In addition, limited studies have suggested the potential for accelerated sintering rates and reduced asymptotic specific surface areas for calcines in the presence of water vapor and carbon dioxide at levels typically found in coal combustors Bortz et al, 1986;Newton et al, 1985). CaSO, has also been shown to accelerate CaO surface area reduction (Glasson, 1967).…”