Kinetic Analysis of Sulfation of Fe-Ca Based Sorbent for FGD

Abstract:

Sulfation performance of a Fe-Ca based sorbent prepared from iron oxide-rich metallurgical dust and lime is investigated using thermogravimetric analysis (TGA) in the temperature range of 300-550°C, and the kinetics of the sulfation reaction is analyzed using the grain model. Comparison between the model simulation results and experimental data demonstrates that the grain model can give a relatively satisfactory description of the experimental results. In detail, the overall rate of the sulfation reaction is mainly controlled by diffusion, despite by chemical kinetics at a very low degree of conversion (lower than 0.056), and that the higher diffusion activation energy (E _D, 25460J/mol) and smaller diffusion frequency factor (D _e0,4.42×10^–2 cm²/min), in relative to those of the sulfation reaction (13008J/mol for E a and 1.65 cm/min for k _s0), may account for the shift in control mechanism, the role of diffusion in the sorbent conversion, and consequently the flat-convex conversion vs. time curves obtained by TGA.

• Periodical: Key Engineering Materials (Volumes 512-515)
• Pages: 1093-1097
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.512-515.1093
• Online since: June 2012
• Authors: Rong Fang Zhao, You Liang Shen, Cheng Xiang Ruan, Wei Min Gao
• Keywords: Grain Model, Solid Waste, Sorbent, Sulfation

References

[1] J.M. Hao, S.X. Wang, Y.Q. Lu, Handbook on Control Technologies of Sulfur Dioxide Emitted from Coal Combustion, Chemical Industry Press, Beijing, 2001.

[2] P.S. Lowell, K. Schwitzgebel, T.B. Parsons and K.J. Sladek, Selection of metal oxides for removing SO2 from flue gas, Ind. Eng. Chem. Process Des. Develop. 10 (1971) 384-390.

DOI: 10.1021/i260039a018

[3] Z.U. Bekir, I. Aksahin, Y. Hayrettin, Sorption of SO2 on metal oxides in a fluidized bed, Ind. Eng. Chem. Res. 27 (1988) 434-439.

DOI: 10.1021/ie00075a012

[4] R.F. Zhao, S.F. Ye, Y.F. Chen and Y.S. Xie, Characteristics and reactivities of solid wastes sorbents for medium-temperature flue gas desulfurization, Energy Sources, Part A 29 (2007) 769-780.

DOI: 10.1080/009083190965532

[5] J. Szekely, J.W. Evans, H.Y. Sohn, Gas-Solid Reaction, Academic Press, NewYork, 1976.

[6] H.Y. Sohn, J. Szekely, A structural model for gas-solid reactions with a moving boundary: III. General dimensionless representation of the irreversible reaction between a porous solid and a reactant gas, Chem. Eng. Sci. 27 (1972) 763-778.

DOI: 10.1016/0009-2509(72)85011-5

[7] K.Nilgum, E.M. Aysegul, Y. Reha and K. Sadrive, Kinetic model for desulfurization at low temperature using hydrated sorbent, Thermochimica Acta 335 (1999) 127-134.

DOI: 10.1016/s0040-6031(99)00175-6

[8] Y. Suyadal, H.Oguz, Dry desulfurization of simulated flue gas in a fluidized-bed reactior for a broad range of SO2 concentration and temperature: A comparison of models, Ind. Eng. Chem. Res. 38 (1999) 2932-2939.

DOI: 10.1021/ie9805077

[9] K.T. Lee, O.W. Koon, Modified shrinking unreacted-core model for the reaction between sulfur dioxide and coal fly ash/CaO/CaSO4 sorbent, Chem. Eng. J. 146 (2009) 57-62.

DOI: 10.1016/j.cej.2008.05.012

[10] H.L. Fan, Y.X. Li, C.H. Li, H.X. Guo and K.C. Xie, The apparent kinetics of H2S removal by zinc oxide in the presence of hydrogen, Fuel 81 (2002) 91-96.

DOI: 10.1016/s0016-2361(01)00111-9

[11] J. Szekely, J.W. Evans, A structural model for gas-solid reactions with a moving boundary. II. Effect of grain size, porosity and temperature on the reaction of porous pellets, Chem. Eng. Sci. 26 (1971) 1901-1913.

DOI: 10.1016/0009-2509(71)86033-5