MODELING CHAR OXIDATION AS A FUNCTION OF PRESSURE ...

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Coal Table A.3. Proximate Analysis for All Coals Moisture (wt% as received) 150 Ash (wt% dry) Volatiles (wt% dry) Koonfontain 0.82 12.24 25.79 Middleburg 0.86 8.79 33.67 Han Cheng 0.41 29.79 15.21 Yang Quan 4.39 10.73 36.78 Pittsburgh 1.28 11.01 37.64 Cerrejon 2.11 6.81 38.58 Table A.4. Moisture, Ash and ICP Mass Release Data for Koonfontain and Middleburg Chars at the 1" Sampling Height (14 ms) Koonfontain Middleburg Reactor condition #1 #2 #3 #4 #1 #2 #3 #4 Sampling height 1” 1” 1” 1” 1” 1” 1” 1” Moisture (wt% as rec'd) 0.24 0.17 0.36 0.16 0.89 0.20 0.54 0.30 Ash (wt% dry) 18.91 20.52 18.69 20.63 16.02 16.64 15.66 17.25 Mass release (daf) for different tracers Ti 40.77 47.12 40.75 47.75 49.89 52.02 48.39 53.60 Si 42.35 47.35 40.48 48.80 48.33 50.62 46.88 52.59 Al 41.61 46.68 39.97 47.88 49.32 51.83 47.10 52.94 ash 40.19 45.97 39.32 46.35 49.51 51.76 48.13 53.80 Mass balance* 46.5 49.0 43.7 49.2 54.3 54.1 51.9 55.0 * Mass balance means the mass release of the char is calculated from the amount of char collected and the amount of coal fed.
Table A.5. Moisture, Ash and ICP Mass Release Data for Koonfontain Chars at Greater Sampling Heights Name of coal Koonfontain Reactor condition #2 #2 #2 #4 #4 #4 Sampling height 2” 4” 6” 2” 4” 6” Residence time (ms) 25 44 63 25 44 63 Moisture (wt% as rec'd) 0.483 0.176 0.465 0.317 0.548 0.478 Ash (wt% dry) 20.55 21.72 23.18 20.95 23.94 26.24 Mass release (daf) for different tracers Ti 49.19 51.16 53.95 49.65 57.65 61.95 Si 69.54 † 70.86 † 151 73.01 † 49.32 58.27 62.07 Al 47.04 50.76 54.38 48.13 57.87 61.99 ash 45.76 49.45 53.51 48.11 56.32 61.35 Mass balance* 50.7 58.7 64.3 † Suspect data * Mass balance means the mass release is based on the amount of coal fed and the amount of char collected in the experiment. Table A.6. Moisture, Ash and ICP Mass Release Data for Four Chars Prepared under CH 4 Fuel-lean Condition (at the 1" sampling height) Name of coal Cerrejon Yan Quan Pittsburgh Han Cheng Moisture (wt% as rec'd) 0.27 0.40 0.39 0.00 Ash (wt% dry) 14.03 23.41 23.86 36.68 Mass release (daf) for different tracers Ti 56.52 62.80 61.84 28.98* Si 57.23 63.63 62.17 20.90* Al 58.15 62.55 63.53 28.86* ash 55.18 60.66 60.49 27.38* Mass balance 61.5 63.7 77.0 66.3 * Suspect data
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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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Effective Diffusivity The major obs
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where r p1 and r p2 are the average
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where r p1 is the macro-pore radius
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7. Model Evaluation and Discussion
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experiments are non-porous, the rat
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and 2850 K). For consistency with t
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The value of the roughness factor w
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= S int S ext D e r p a 2 2M C M O2
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Reactor Head Flow Straightener Reac
Page 119 and 120: the large size of the particle, and
Page 121 and 122: taking into account convection, rad
Page 123 and 124: 2.5x10 -4 2 /sec) 2.0 1.5 Rate (g/c
Page 125 and 126: Table 7.5. The Experimental Conditi
Page 127 and 128: The burnout and particle velocity d
Page 129 and 130: The HP-CBK was used to predict the
Page 131 and 132: TGA and FFB Data-This Study The rea
Page 133 and 134: This equation can be derived as fol
Page 135 and 136: q = A 1p e − E 1 p / RT P os 1 +
Page 137 and 138: m obs = 0 at high temperatures) and
Page 139 and 140: Currently the correlations between
Page 141 and 142: 8. Summary and Conclusions The obje
Page 143 and 144: 0.5 due to the contribution from th
Page 145 and 146: Langmuir rate equation, the reactio
Page 147 and 148: II, in agreement with many observat
Page 149 and 150: 9. Recommendations The predictive c
Page 151 and 152: References Ahmed, S., M. H. Back an
Page 153 and 154: Essenhigh, R. H., D. Fortsch and H.
Page 155 and 156: Mehta, B. N. and R. Aris , “Commu
Page 157 and 158: Szekely, J. and M. Propster, "A Str
Page 159 and 160: Appendices 139
Page 161 and 162: Introduction Appendix A: Experiment
Page 163 and 164: detaching the flame from the burner
Page 165 and 166: To study the effects of steam, CO w
Page 167 and 168: times at heights of 1, 2, 4, and 6
Page 169: analysis. The char reactivities (in
Page 173 and 174: Table A.9. Elemental Analyses of Fo
Page 175 and 176: temperature profile of the post-fla
Page 177 and 178: Apparent densities 1.00 0.75 0.50 0
Page 179 and 180: This observation is somewhat surpri
Page 181 and 182: It is interesting to compare Figure
Page 183 and 184: The N 2 BET surfacea areas and H/C
Page 185 and 186: collected in the #4 reactor conditi
Page 187 and 188: Rate (gC /g C remaining /sec) 1.6x1
Page 189 and 190: close to zero, the accumulated erro
Page 191: Appendix B: Errors and Standard Dev
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