Combined calcination, sintering and sulfation model for CaCO{sub 3}-SO{sub 2} reaction
- Ohio State Univ., Columbus, OH (United States). Dept. of Chemical Engineering
A mathematical model developed accounts for the multiple rate processes involved in the reaction of solid CaCO{sub 3} or Ca(OH){sub 2} with SO{sub 2} at high temperatures in the combustion environment. The model, based on the grain-subgrain concept, considers the concomitantly occurring calcination, sintering and sulfation reactions and their interactive effects on pore structure and reaction kinetics. It incorporates internal diffusion, reaction, and product layer diffusion in simulating the calcination of the CaCO{sub 3} grain and subsequent sintering and sulfation occurring on the CaO subgrains. It is the first sulfation model to incorporate the true mechanism of diffusion through the solid product phase: the solid-state ionic diffusion of Ca{sup 2+} and O{sup 2{minus}} ions in a coupled manner through the nonporous CaSO{sub 4}. Its predictions are compared with the random pore model and the grain model using experimental CaO sulfation data from the literature as well as short-contact-time CaCO{sub 3} and Co(OH){sub 2} sulfation data reported previously. Mahuli et al. (1997) discussed a high reactivity modified calcium carbonate synthesized by optimizing the pore structural properties. This modified CaCO{sub 3} can convert 70--75% of sulfation within 0.5 s, which is substantially higher than any other sorbents reported for similar particle size and reaction conditions. The model is used to predict the calcination and sulfation kinetics, as well as to simulate the surface area evolution of the modified CaCO{sub 3}, which provides further insights into its exceptional reactivity.
- OSTI ID:
- 329248
- Journal Information:
- AIChE Journal, Journal Name: AIChE Journal Journal Issue: 2 Vol. 45; ISSN 0001-1541; ISSN AICEAC
- Country of Publication:
- United States
- Language:
- English
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