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.