I have updated the kinetic model with information from the following sources-
coke oxidation: Kanervo et al.
These reactions will vary with the catalyst.
homogeneous CO oxidation: Howard et al.
catalyst promoted CO oxidation: Tone et al.
This reaction will vary with the presence and activity of oxidation promoter on the catalyst.
For oxidation of the hydrogen in the coke, I include it in the carbon oxidation reactions. This assumption is based on my belief that the coke consists of hydrocarbons and the breakup of a hydrocarbon molecule results in oxidation of both the carbon and hydrogen. This assumption also means I don't have to maintain an adsorbed hydrogen balance or have a separate reaction for the formation of water.
What has changed?
The major change is that increasing the value of "f", the fraction of air to the bubble phase determined by the tracer study, no longer increases the afterburn temperature difference. The reason for this change appears to be the higher activation energies for the reactions involving the catalyst than what I had previously assumed.
Impact on the analysis of the reactor in the CFD study (see previous post)
The catalyst size and fluidization behavior and the short bed height remain as a prime candidates for the high amount of afterburn. Also, increasing the air flow well beyond the onset of bubble flow results in higher afterburn. Because of the poor fluidization in the dense bed, the air flow rate probably has been raised to achieve the coke level desired. The additional coke burn occurs in the freeboard region.
Howard, J.B., Williams, G.C., Fine, D.H. (1973). Kinetics of Carbon Monoxide Oxidation in Post Flame Gases. In 14th Symposium (International) on Combustion, Pittsburgh, The Combustion Institute
Kanervo, J. M., a. O I Krause, J. R. Aittamaa, P. H. Hagelberg, K. J T Lipiäinen, I. H. Eilos, J. S. Hiltunen, and V. M. Niemi. “Kinetics of the Regeneration of a Cracking Catalyst Derived from TPO Measurements.” Chemical Engineering Science 56 (2001): 1221–27
Tone, S., Miura, S.I., Otake, T., (1972). Kinetics of oxidation of coke on silica-alumina catalysts. Bull. Jap. Petrol. Inst., 14(1), 76