• The CO/CO 2 product ratio is a major uncertainty in char oxidation modeling. It likely depends on the total gas pressure and the oxygen partial pressure. More work should be conducted to address this issue. 130
References Ahmed, S., M. H. Back and J. M. Roscoe, “A Kinetic Model for the Low Temperature Oxidation of Carbon: I,” Combustion and Flame, 70, 1 (1987). Aris, R., The Mathematical Theory of Diffusion and Reaction in Permeable Catalysts, Clarendon Press, Oxford, UK (1975). Arthur, J. R., “Reaction Between Carbon and Oxygen,” Trans. Faraday Soc., 47, 164 (1951). Balzhiser, R. E. and K. E. Yeager, "Coal-Fired Power Plants for the Future", Scientific American, 9, 100 (1987). Banin V., R. Moors and B. Veefkind, “Kinetic Study of High-Pressure Pulverized Coal Char Combustion: Experiments and Modeling”, Fuel 76, 945 (1997a). Banin, V. E., F. A. C. M. Commissaris, J. H. J. Moors and A. Veefkind, "Kinetic Study of Pulverized Coal Combustion at High Pressure Using a Shock Tube", Combustion and Flame, 108, 1 (1997b). Bar-Ziv, E., D. B. Jones, R. E. Spjut, D. R. Dudek, A. F. Sarofim and J. P. Longwell, "Measurement of Combustion Kinetic of a Single Char Particle in an Electrodynamic Thermogravimetric Analyser", Combustion and Flame, 75, 81 (1989). Bateman, K. J., “Millimeter Sized Coal Particle Combustion at Elevated Pressures”, M.S. Thesis, Brigham Young University (1993). Bateman, K. J., G. J. Germane, L. D. Smoot and C. N. Eatough, “A Facility for High- Pressure Measurement of Reaction Rates of Millimeter-Sized Coal,” Energy and Fuels, 9, 295 (1995). Bird, R. B., W. R. Stewart and E. N. Lightfoot, Transport Phenomena, John Wiley and Sons, New York (1960). Bischoff, K. B., “Effectiveness Factor for General Reaction Rate Forms,” A.I.Ch.E Journal, 11, 351 (1965). Blyholder G. and H. Eyring, “Kinetics of Graphite Oxidation. II,” J. Phys. Chem., 63, 1004 (1959). 131
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MODELING CHAR OXIDATION AS A FUNCTI
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BRIGHAM YOUNG UNIVERSITY As chair o
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CBK model uses: 1) an intrinsic Lan
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Table of Contents List of Figures..
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Appendices.........................
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Figure A.2. Mass releases of the Ko
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Table 7.6. Parameters Used in Model
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Ed activation energy of desorption,
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vc the volume of combustible materi
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Background 1. Introduction The rate
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the CBK model developed at Brown Un
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Zone III rate ∝ C og E obs → 0
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coal-general kinetic rate constants
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Boundary Layer Diffusion The molar
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= q obs q max The factor can be use
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where k 1 and K are two kinetic par
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particle can therefore be convenien
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This is the first time that the gen
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Data of Mathias Mathias (1996) perf
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urn with shrinking diameters, and t
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3. Objectives and Approach The obje
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Introduction 4. Analytical Solution
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Task and Methodology Task One of th
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2 [ (i +1) − (i − 1)] i b = −
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Table 4.1. The Relative Error * (%)
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The resulting observations regardin
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correction. The values of functions
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Table 4.6. The Relative Error* (%)
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Table 4.8. The Relative Error* (%)
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general asymptotic solution. An arc
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5. Theoretical Developments The int
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order of a reaction is usually dete
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nobs = 1 (KCs ) 2 2 1 [KCs − ln(1
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The observed reaction order in Zone
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Bulk Diffusion vs. Knudsen Diffusio
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where D K is in cm 2 /sec, r p is t
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where T p is in K, P is in atm. The
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Both of these assumptions are argua
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2 r obs ′ − [kD Pog + k d + kD
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oxygen partial pressure (Suuberg et
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Farrauto and Batholomew (1997) prop
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assumes a homogeneous, non-interact
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Single-Film Char Oxidation Submodel
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where and An energy balance is used
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where is the empirical burning mode
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calculation uses a 7 × 7 × 7 matr
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HP-CBK Model Development The HP-CBK
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