MODELING CHAR OXIDATION AS A FUNCTION OF PRESSURE ...

More documents

Recommendations

Info

Table A.7. Elemental Analyses of Middleburg Coal and Chars (1" sampling height) C% H% N% S% Sum O%(dif) H/C Coal dry 75.33 4.92 1.643 0.501 82.4 0.784 daf 82.59 5.40 1.80 0.55 90.3 9.66 Char 1 dry 78.88 1.39 1.568 0.309 82.1 0.214 daf 93.93 1.58 1.79 0.35 93.6 6.40 Char 2 dry 79.84 0.80 1.501 0.310 82.4 0.120 daf 95.77 0.96 1.80 0.37 98.9 1.10 Char 3 dry 78.58 1.78 1.652 0.306 82.3 0.272 daf 93.17 2.11 1.96 0.36 97.6 2.39 Char 4 dry 80.56 0.63 1.535 0.271 83.0 0.094 daf 97.36 0.76 1.85 0.33 100.3 -0.30* *Negative value for oxygen concentration by difference due to errors in CHNS and ash analyses. Table A.8. Elemental Analyses of Koonfontain Coal and Chars (1" sampling height) C% H% N% S% Sum O%(dif) C/H Coal dry 72.02 4.27 1.83 0.56 78.7 0.712 daf 82.07 4.86 2.09 0.64 89.7 10.35 Char 1 dry 75.26 1.47 1.60 0.33 78.7 0.234 daf 92.81 1.81 1.98 0.41 97.0 2.99 Char 2 dry 80.07 0.58 1.52 0.28 82.7 0.087 daf 100 * Char 3 dry 76.23 1.85 1.74 0.31 80.1 0.291 daf 93.75 2.28 2.14 0.39 98.6 1.55 Char 4 dry 78.29 0.55 1.51 0.29 80.6 0.084 * Negative %O. daf 98.65 * 152
Table A.9. Elemental Analyses of Four Coals and Their Chars Prepared at CH 4 Fuel-lean Condition C% H% N% S% Sum O%(dif) C/H Yan Quan coal dry 70.42 4.75 1.24 0.573 0.810 Yuan Quan char #2 daf 78.89 5.32 1.39 0.642 86.24 13.76 dry 83.86 0.99 1.19 1.16 0.142 daf * Cerrejon coal dry 75.73 5.21 1.64 1.14 0.825 Cerrejon char #2 daf 81.26 5.59 1.76 1.22 89.83 10.17 dry 85.97 0.69 1.69 0.70 0.096 daf * Han Cheng coal dry 59.83 3.13 1.16 2.34 0.629 Han Cheng char #2 daf 85.21 4.46 1.65 3.34 94.66 5.34 dry 62.46 0.50 1.00 0.77 64.73 0.096 daf * Pittsburgh coal dry 72.09 4.87 1.55 5.29 0.810 Pittsburgh char #2 * Negative %O by difference. daf 81.01 5.48 1.76 5.94 94.17 5.83 dry 71.80 0.63 1.35 4.24 0.105 daf 94.30 0.825 1.77 5.56 102.5 * 153
Page 1 and 2:
MODELING CHAR OXIDATION AS A FUNCTI
Page 3 and 4:
BRIGHAM YOUNG UNIVERSITY As chair o
Page 5 and 6:
CBK model uses: 1) an intrinsic Lan
Page 7 and 8:
Table of Contents List of Figures..
Page 9:
Appendices.........................
Page 12 and 13:
Figure A.2. Mass releases of the Ko
Page 14 and 15:
Table 7.6. Parameters Used in Model
Page 16 and 17:
Ed activation energy of desorption,
Page 18 and 19:
vc the volume of combustible materi
Page 21 and 22:
Background 1. Introduction The rate
Page 23:
the CBK model developed at Brown Un
Page 26 and 27:
Zone III rate ∝ C og E obs → 0
Page 28 and 29:
coal-general kinetic rate constants
Page 30 and 31:
Boundary Layer Diffusion The molar
Page 32 and 33:
= q obs q max The factor can be use
Page 34 and 35:
where k 1 and K are two kinetic par
Page 36 and 37:
particle can therefore be convenien
Page 38 and 39:
This is the first time that the gen
Page 40 and 41:
Data of Mathias Mathias (1996) perf
Page 42 and 43:
urn with shrinking diameters, and t
Page 45 and 46:
3. Objectives and Approach The obje
Page 47 and 48:
Introduction 4. Analytical Solution
Page 49 and 50:
Task and Methodology Task One of th
Page 51 and 52:
2 [ (i +1) − (i − 1)] i b = −
Page 53 and 54:
Table 4.1. The Relative Error * (%)
Page 55 and 56:
The resulting observations regardin
Page 57 and 58:
correction. The values of functions
Page 59 and 60:
Table 4.6. The Relative Error* (%)
Page 61 and 62:
Table 4.8. The Relative Error* (%)
Page 63 and 64:
general asymptotic solution. An arc
Page 65 and 66:
5. Theoretical Developments The int
Page 67 and 68:
order of a reaction is usually dete
Page 69 and 70:
nobs = 1 (KCs ) 2 2 1 [KCs − ln(1
Page 71 and 72:
The observed reaction order in Zone
Page 73 and 74:
Bulk Diffusion vs. Knudsen Diffusio
Page 75 and 76:
where D K is in cm 2 /sec, r p is t
Page 77 and 78:
where T p is in K, P is in atm. The
Page 79 and 80:
Both of these assumptions are argua
Page 81 and 82:
2 r obs ′ − [kD Pog + k d + kD
Page 83 and 84:
oxygen partial pressure (Suuberg et
Page 85 and 86:
Farrauto and Batholomew (1997) prop
Page 87:
assumes a homogeneous, non-interact
Page 90 and 91:
Single-Film Char Oxidation Submodel
Page 92 and 93:
where and An energy balance is used
Page 94 and 95:
where is the empirical burning mode
Page 96 and 97:
calculation uses a 7 × 7 × 7 matr
Page 98 and 99:
HP-CBK Model Development The HP-CBK
Page 100 and 101:
Effective Diffusivity The major obs
Page 102 and 103:
where r p1 and r p2 are the average
Page 104 and 105:
where r p1 is the macro-pore radius
Page 107 and 108:
7. Model Evaluation and Discussion
Page 109 and 110:
experiments are non-porous, the rat
Page 111 and 112:
and 2850 K). For consistency with t
Page 113 and 114:
The value of the roughness factor w
Page 115 and 116:
= S int S ext D e r p a 2 2M C M O2
Page 117 and 118:
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 and 170: analysis. The char reactivities (in
Page 171: Table A.5. Moisture, Ash and ICP Ma
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
show all

MODELING CHAR OXIDATION AS A FUNCTION OF PRESSURE ...

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?