MODELING CHAR OXIDATION AS A FUNCTION OF PRESSURE ...
MODELING CHAR OXIDATION AS A FUNCTION OF PRESSURE ... MODELING CHAR OXIDATION AS A FUNCTION OF PRESSURE ...
experiments (and reported by many researchers as true activation energies) are actually still coupled with mass diffusion effects in the micropores. TGA Reactivities: Effects of Coal Types Chars were prepared from all six parent coals (Koonfontain, Middleburg, Cerrejon, Yang Quan, Pittsburgh, and Han Cheng coals) under CH 4 fuel-lean condition at 1” sampling height. The TGA reactivities of these chars were measured at 550 °C in 10 mole- % O 2 and plotted in Figure A.8. 2.4x10 -3 Rate (g C /g C remaining /sec) 2.2 2.0 1.8 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0.0 0 Cerrejon 20 Middleburg 40 162 Yang Quan %Burnout Pittsburgh 60 Koonfontain Han Cheng Figure A.8. TGA reactivities of all chars (prepared under CH 4 fuel-lean condition, collected at 1” sampling height) measured at 550 C in 10 mole-% oxygen. 80 100
The N 2 BET surfacea areas and H/C ratios of these chars are plotted in Figure A.9. The chars are in the order of decreasing TGA reactivity from left to right in Figure A.9. It can be seen that the N 2 surface areas and H/C ratios tend to decrease from left to right with a few exceptions. This means TGA reactivities are correlated with N 2 surface areas and H/C ratios even for chars of different parent coals. N 2 surface area and 1000*H/C ratio 160 140 120 100 80 60 40 20 0 Yang Quan Pittsburgh Middleburg Cerrejon Koonfontain Han Cheng N2 surface area 1000x H/C Figure A.9. N 2 surface areas and H/C ratios of six chars (at condition #2 and 1” sampling height) High Temperature Reactivity The percent of the daf mass remaining (m/m 0) of Koonfontain chars #2 and #4 from high temperature FFB experiments are plotted as functions of residence time in Figure A.10. The reactivities based on (a) the amount of carbon available in the particles, and (b) the external surface area of a representative particle (which has an average particle size), are shown in Figures A.11 and A.12. From Figures A.11 and A.12 it can be seen that the average (i.e., last set of bars) high temperature reactivity of char #4 is about twice 163
- 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 and 172: Table A.5. Moisture, Ash and ICP Ma
- 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: It is interesting to compare Figure
- 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
The N 2 BET surfacea areas and H/C ratios of these chars are plotted in Figure A.9.<br />
The chars are in the order of decreasing TGA reactivity from left to right in Figure A.9. It<br />
can be seen that the N 2 surface areas and H/C ratios tend to decrease from left to right<br />
with a few exceptions. This means TGA reactivities are correlated with N 2 surface areas<br />
and H/C ratios even for chars of different parent coals.<br />
N 2 surface area and 1000*H/C ratio<br />
160<br />
140<br />
120<br />
100<br />
80<br />
60<br />
40<br />
20<br />
0<br />
Yang Quan<br />
Pittsburgh<br />
Middleburg<br />
Cerrejon<br />
Koonfontain<br />
Han Cheng<br />
N2 surface area 1000x H/C<br />
Figure A.9. N 2 surface areas and H/C ratios of six chars (at condition #2 and 1”<br />
sampling height)<br />
High Temperature Reactivity<br />
The percent of the daf mass remaining (m/m 0) of Koonfontain chars #2 and #4<br />
from high temperature FFB experiments are plotted as functions of residence time in<br />
Figure A.10. The reactivities based on (a) the amount of carbon available in the particles,<br />
and (b) the external surface area of a representative particle (which has an average particle<br />
size), are shown in Figures A.11 and A.12. From Figures A.11 and A.12 it can be seen<br />
that the average (i.e., last set of bars) high temperature reactivity of char #4 is about twice<br />
163
Change language