Open AccessREMOVAL OF H{sub 2}S AND SO{sub 2} BY CaCO{sub 3}-BASED SORBENTS AT HIGH PRESSURES
Author(s) -
Stratis V Sotirchos
Publication year - 1999
Language(s) - English
Resource type - Reports
DOI - 10.2172/786381
Subject(s) - sulfidation , calcination , carbonation , thermogravimetric analysis , chemistry , mineralogy , atmospheric pressure , particle size , analytical chemistry (journal) , calcium carbonate , diffusion , decomposition , thermodynamics , geology , environmental chemistry , biochemistry , sulfur , oceanography , physics , organic chemistry , catalysis
The effects of various operating and process parameters on the direct sulfidation of limestones, that is, their reaction with H{sub 2}S in the presence of CO{sub 2} at concentrations large enough to prevent the decomposition of CaCO{sub 3} to CaO. Two calcitic solids of high calcium carbonate content (over 97%) were employed in the experiments, and the reaction was studied in a thermogravimetric analysis system that can operate at pressures above atmospheric. Pressures in the 1-4 atm range were employed. The results showed that the pressure influenced the behavior of the process mainly through its effects on the concentration of H{sub 2}S, and the rate of the reaction was found to be of first order with respect to this variable. The behavior of the process could be described satisfactorily by a shrinking core model with a product layer diffusivity that depended only on the temperature and did not vary with the distance from the external surface of the particles. The results on the effects of particle size, temperature, limestone sample, and concentration of H{sub 2}S were in agreement with those in a past investigation of the direct sulfidation reaction of limestones in our laboratory at atmospheric pressure. For the next six-month period, we plan to conduct experiments on the effects of the effects of carbonation reaction on the sulfation of calcined limestones. As explained in the introductory section of this report, this situation may occur as calcined particles move into areas of the combustor where the concentration of CO{sub 2} is above the equilibrium value for the calcination reaction at the prevailing temperature