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Experimental gas-solid reaction kinetics of lime sulfation

Technical Report ·
OSTI ID:5930120
Results from TGA confirmed that sulfation of CaO produces different products at different reaction conditions. In the presence of oxygen, above 740/sup 0/C, the product is all CaSO/sub 4/ and the reaction is first order in SO/sub 2/ concentration. At 836/sup 0/C, the reaction rate constant is 0.076 cm/s with an activation energy of 19.1 kcal/mole. Below 450/sup 0/C, the major product is CaSO/sub 3/ and the reaction is zero order. The zero order reaction rate constant at 450/sup 0/C is 4.2 x 10/sup -8/ cm/s with an activation energy of 15.4 kcal/mole. The grains of CaO obtained by calcining Ca(OH)/sub 2/ contained micropores, with a large number of them around 22 A in radius. The effect of sintering and sulfation on the micropores was studied using mercury porosimetry. At 932/sup 0/C, the solid-state diffusivity was found to be 40 x 10/sup -8/ cm/sup 2//s with an activation energy of 35.6 kcal/mole. Reaction measurements on sintered and unsintered CaO pellets showed that the temperature for maximum conversion increased with either increasing initial porosity or increasing initial grain size. A one-dimensional expanding grain model, applied to the lime pellet sulfation data, fit the data from highly sintered pellets quite well.
Research Organization:
Ames Lab., IA (USA)
DOE Contract Number:
W-7405-ENG-82
OSTI ID:
5930120
Report Number(s):
IS-T-1056; ON: DE83016141
Country of Publication:
United States
Language:
English