Study and Kinetic Modeling of Direct Sulfation of Iranian Limestones by Sulfur Dioxide at High CO2 Partial Pressure

Document Type : Research Article


Faculty of Chemical Engineering, Amirkabir University of Technology, P.O. Box 1587- 4413 Tehran, I.R. IRAN


The direct sulfation of three high purity Iranian limestones and one precipitated calcium carbonate from different sources, containing more than 97 % CaCO3, were studied in a specially designed fixed bed reactor under atmospheric pressure, in the presence of excess CO2 to prevent decomposition of CaCO3. Experiments were carried out over a range of particle sizes from 1.6-2.5  mm at four temperatures (750, 800, 850, 900 °C), and SO2 concentration of 2400 ppm. The particle size and temperature showed a dominant influence on the variation of conversion with time. The results of experiments show that the Shrinking Unreacted Core Model can beused to predict the behavior of sulfation of limestone. This simple model reveals that the reaction rate is the controlling step. The parameter of model, chemical rate constant (Ks), was obtained as: Ks = 0.1 exp (-6.2/RT)  cm/s. Model predictions are in good agreement with expeimental data.


Main Subjects

[1] Ramachandran, P.A., Doraiswamy, L.K., Modeling of Non - Catalytic Gas-Solid Reaction, AIChE J., 28, 881 (1982).
[2] Dennis, J.S., Hayhurst, A.N., A Simplified Analytical Model for the Rate of Reaction of SO2 with Limestone Particle, Chem. Eng. Sci., 41,25 (1986).
[3] Hajaligol, M. R.,  Longwell, J. P.,  Sarofim, A. F., Analysis and Modeling of the Direct Sulfation of CaCO3, Ind. Eng. Chem. Res., 27, 2203 (1988).
[4] Snow, M.J.H., Longwell, J.P., Sarofim, A.F., Direct Sulfation of Calcium Carbonate, Ind. Eng. Chem. Res., 27, 268 (1988).
[5] Fuertes, A.B., Velasco, G., Fuente, E., Alvarez, T., Study of the Direct Sulfation of Limestone Particles at High CO2 Partial Pressure, Fuel Processing Technology, 38, 181 (1994).
[6] Krishnan, S.V., Sotirchos, S.V., A Variable Diffusivity Shrinking Core Model and its Application to the Direct Sulfation of Limestone, Canadian J. Chem. Eng., 71, 734 (1993).
[7] Tullin, C., Ljungstrom, E. , Reaction between Calcium Carbonate and Sulfur Dioxide, Energy & Fuels, 3, 284 (1989).
[8] Zarkanitis, S., Sotrichos, S.V., Pore Structure and Particle Size Effect on Limestone Capacity for SO2 Removal, AIChE J., 821 (1989).
[9] Iisa, K., Hupa, M., Yrjas, P., Product Layer Diffusion in the Sulfation of Calcium Carbonate, Proceeding of 24th Symposium on Combustion, 1349 (1992).
[10] Civrowa,  K.W.,  Application  on  Thermoanalytical Methods to the Study of Limestone Sulfation”,  
J. Thermal Analysis, 43, 193 (1995).
[11] Rahmani, M., Sulfur Dioxide Removal from Flue-Gas by Direct Sulfation of CaCO3, MSc. Thesis, Chem. Eng. Dept., AmirkabirUniversity of Technology, IRAN, (1997).
[12] Brogen, C., Karlsson, H., Modeling the Absorption of SO2 in a Spray Scrubber Using the Penetration Theory”, Chem. Eng. Sci., 52, 3085 (1997).
[13] Nikazar, M., Hallaj, R., Rahmani, M., Dabir, B., Hajaligol, M.R., Direct Sulfation of Limestone by Sulfur Dioxide, Pakistan J. App. Sci., 2, 158 (2002).
[14] Nikazar, M., Hallaj, R., Dabir, B., Thermogravimetric Study of Direct Sulfation of Limestone by SO2,
6th Asia-Pacific International Symp. on Combustion & Energy Utilization, Malaysia, (2002).
[15] Liu,  H.,  Katagiri,  S.,  Kaneko,  U., Okazaki, K., Sulfation Behavior of Limestone under High CO2 Concentration in O2/CO2 Coal Combustion, Fuel, 79, 945  (2000).
[16] Borgwardt, R. H., Bruce, K. R., Blake,  J.,  An Investigation of Product Layer Diffusivity for CaO Sulfation, Ind. Eng. Chem. Res., 26, 1993 (1987).
[17] Spartinos, D.M., Vayenas, C.G., Kinetics of Sulfation of Limestone and Precalcined Imestone, Chem. Eng. Proc., 30, 97 (1991).
[18] Szekely, J., Evans, J.W., Sohn, H.Y., Gas-Solid Reactions, 1st Ed. Academic, Chaps. 3, 4 (1976).
[19] Qiu, K., Lindqvist, O., Direct Sulfation of Limestone at Elevated Pressures, Chemical Engineering Science, 55 (16), 3091 (2000).
[20] Dom-Johanson, K., Ostergaard, K., High Temperature Reaction between Sulfur Dioxide and Limestone, Chem. Eng. Sci., 46, 836 (1993).
[21] Bhatia, S.K., Perlmuter, D.D., The Effect of Pore Structure on Fluid-Solid Reactions: Application to SO2-Lime Reaction, AIChE J., 27, 226 (1981).
[22] Hu, G., Dam-Johansen, K., Wedel, S., Hansen, J.P., Review of the Direct Sulfation Reaction of Limestone”, Progress in Energy and Combustion Science, 32, 386 (2006).
[23] Hu, G., Dam-Johansen, K., Wedel, S., Hansen, J.P., Direct Sulfation of Limestone, AIChE Journal53(4),  948 (2007).