the coking properties of coal at elevated pressures. - Argonne ...

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from Figure 5, due to the scale, is that the time for total burnaway is the same for each distribution since they all have the same maximum particle size of 3m. Evaluation of C P Equation 27) was numericatly integrated to give the particulate oxygen concentration C for the three distributions. The results are shown in Figure 6. An igteresting feature of these results is the value of Cp at t=o. According to Avedesian and Davidson 17) the value of 5 should be almost zero for the batch fed system but it is clear from Figure 6 that this is not the case. Equations 25), 26) and 27) are valid only for constant temperature and pressure. These conditions are usually met in FBC's except that the particle temperature Tp can vary during burnaway and can be appreciably higher than the bed temperature (4,5,6). The effect of increasing Tp would be to increase the value of k2 relative to kl and the controlling mechanism would tend towards that of diffusion. Increasing the pressure of the system would only have a significant effect if the combustion rate was initially dominated by chemical kinetics. Conclusions A theoretical model has been developed which predicts the change in size distribution during burnaway, burn-out times and particulate phase oxygen concentrations as a function of original particle size distribution in a batch fed fluidised bed. batch fed experiment could be devised to determine the role of chemical kinetics for a given type of coal and would thus be an aid to modelling of fluidised bed combus tion. Acknowledgements If the original size distribution is accurately known a The work described here form part of the activities of the Sheffield Coal Research Unit sponsored by Shell Coal International and the N.C.B.. The authors are grateful for the financial assistance of the Sponsors and wish to point out that the views expressed here are those of the authors and not necessarily those of the Sponsors. We are also grateful to Dr. R.G. Siddall and Dr. P.J. Foster for many illuminating discussions. Nomenclature Constant defined by equation 24) Area of fluidised bed (m2) Rosin-Rammler constant - equation 21) Oxygen exchange parameter - equation 12) Oxygen concentration of fluidising air (mole/m 3 ) 3 Particulate phase oxygen concentration (mole/rn ) Gas diffusion coefficient (m2/s) constant (= l/k2) constant (= l/kl) Defined by equation 12) Function of Oxygen concentration (= 2M C /~p) O P 302
kl k2 k' KC KD m m. m P N P R R g t T Tb T. T P 'mf '0 W X - X. 1 X P Xt X YO Y Z Z Constant defined by equation 2) Constant defined by equation 3) Constant defined by equation 31) Chemical rate constant Diffusional rate constant Mass of char in bed at time t (kg) Initial mass of batch (kg) Mass of single char particle (kg) Function of particle size - equation 25) Pressure (a Em) Reaction rate of single particle (kg/s) Gas constant Burnaway time (S) Temper at ure (0 Bed temperature (0 Reference temperature - equation 30) (K) Particle surface temperature (K) Minimum f luidising velocity (4s) Superficial fluidising velocity (m/s) Weight fraction of coal (kg) Particle diameter (mm) Initial weighted mean particle size (mm) Particle diameter (mm) Particle diameter (m) Dimensionless particle diameter (= x/xi) Particle diameter (mm) Dimensionless particle diameter (= yo/;;) Particle diameter (lower limit of integration) mm Dimensionless particle diameter (= z/xi) 303 J
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I / The Coking Properties of Coal a
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Procedure : Hand picked lunips of c
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Apparatus: The equipment for this t
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the total pressure on the swelling
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A comparison of the results obtaine
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was used, however, general trends a
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1 D 13 3 G
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Table 8 L_ Effect os FaeO Compo.lrl
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i-l SPARE SAblPLE Plortlc 209 Figur
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- z c 100,000 50,000 10,000 0 n 5,0
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Flnure 9 SWELLltlG PROPERTIES OF PI
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Fi ure 13 EFFECT OF TOTAL PRESSQRE,
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TABLE 1. OPERATING CONDITIONS Opera
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1. . 2. 3. 4. 5. 6. 7. 8. 9. REFERE
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Figure 4. SCANNING ELECTRON MICROGR
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Turkgodan et al. (18) studied the p
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Materidl balance on packed bed Boun
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These phenomena iiiay be described
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Walker, P. L., Rusinko, F., and Aus
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-""I- *I,".. I Dlrf".,on Co.1flcl.n
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After a variable residence time, th
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Changes in Char Chemistry The infra
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20. 21. 22. 23. 24. 25. 26. 27. 28.
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0s-a 00-a OS'S 00-E os-2 00-2 02.1
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COAL PYROLYSIS AT HIGH TEMPERATURES
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actions, decreasing the secondary c
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01 40 60 TI MEISeC) 80 100 120 140
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Reaction Temperature OC In-situ Ini
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and the gas velocity is often repre
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The mathematical model developed he
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si sio Fraction of solid species i
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Table 2. Differential Equations Mod
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1 60 I I RUN KE-5 50 T.1121K(1557'F
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to condense excess steam, the press
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conversion-time data.* The integrat
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catalyzed and uncatalyzed runs were
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CATALYTIC EFFECTS OF ALKALI METAL S
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%me thermogravimetric measurements
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than in steam. Figure 9 shows data
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C - C02 REACTION C - H20 REACTION L
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1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11.
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n 'm L u. t m - L 84
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i 5360-096bw \ KINETICS OF POTASSIU
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t 5360-096pj There is an interactio
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1 I > \ i I 5360-096bw bed data. Be
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I 1. I 5360-096bw ranging from atmo
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uY.ku ICHlMAlIC OF MINI-FLUID BE0 R
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800-12-1133 -9 FIGURE IO CALCULATED
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Mexico coal. Table 1 shows an analy
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', Complete results from all runs c
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I the methanol down to atmospheric
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TABLE 3 -----______________________
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\ "I N z 107 c. . 0 0
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I. INTRODUCTION DIRECT METHANATION
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The catalyst development program fo
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Preparing process flow diagrams and
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\ \ i 1. 2,000 4,000 6,000 8,000 10
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(JMS-OlBM-2). The mass spectra were
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I I Fairbridge, R.W. (ed.) 1972, En
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v- W V z d 3 z m 4 ? P m W c3 W m N
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e. \ I , W 2 m 4 t- CI 99-79 noooo
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L Table I: Compositions of High Tem
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\ " \ I For all three coals, the pr
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4 , 1024 1024 3a 3b J Mineral Parti
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The Determination of Mineral Distri
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pyrite crystals in framboids locate
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FIG. 1. TEM MICROGRAPH OF A HIGH VO
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\ \ FIG. 5. SEM MICROGRAPH SHOWING
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\ , species. In fact, combustion ex
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1, It is possible to make a reasona
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\ i SURFACE AND BULK ENRICHMENT OF
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I Coal Ash Sintering Model and the
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5 carried out such sintering measur
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I this ash and other bituminous coa
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forming propensity. However, none o
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t I 153
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CENTRAL ELECTRICIN RESEARCH LABORAT
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157 18 I I a I
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temperature, sulfur species concent
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The facility is fired with coal usi
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Tests have been carried out to dete
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under which conditions sulfur speci
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I TITANIUM L Corn AS A TRACER FOR D
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E 6 i i h \ 1 1 \ on the XRF is cau
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\ ? CONCLUSIONS Titanium can accura
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NY) m * oa
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GFETC constructed a 0.2 square mete
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\: Stage 3. Sulfated ash-cemented a
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I FIG. 1. Initial ash coating on qu
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FIG 9. Limestone bed material alter
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(4) Since the operating temperature
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I I maximum particle diameter leavi
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! suspension chambers and cyclone f
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Pilot Plant of a Coal Fired Fluidiz
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After the fiscal year 1982, the fol
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MBC CBC Fig. 1 Boiler Structure 193
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\ i Table 2. Coal Properties Planne
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-2- more than 3 years, since 1977.
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, I B. 2 which temporarily raised t
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-6- abrasion rate at the bottom of
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\if F3.3 - Particulate Circulation
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\' I/O. analog 1/13. industrial I/O
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ACQUISITION DATA UNIT < I L- J (T)
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SAMPLING SYSTEM FOR FLUIDIZED BED A
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GAS SAMPLING WITH ORIGINAL PROBE-FI
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Remove the quartz tube (gas sample
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' ' The modifications have been com
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n n D 217
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With regard to the similarity parti
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i \ ' 2.2. soz Emission and NOx Emi
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223
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Figure 9: Sulphur captLTre as 0 fun
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P SUMMARY OF TESTS Testing complete
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I Table 1 Comparison of Sulfur Capt
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, NITROGEN OXIDE REDUCTION Single-S
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0 The addition of air at the 96-inc
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m- Y i? 4: BO n 8 c Y l0- Bo- I I I
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E! w 2 z e Y 100 - 3 t 5 80- 0, 40
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0 f 0.so o'm: 0.300 0.zo - - A 5m 4
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&e- -A \ \ \ : ERCENT OVERBED AIR I
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PARTICLE ENTRAINMENT AND NITRIC OXI
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i 1' 1 ! I. i Chaung (15) showed th
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The maximum height that a large par
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3.0 Nitric Oxide Reduction in the F
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Page 253 and 254: Nomenclature A *t cD ‘NO $3 _ _ _
Page 255 and 256: TABLE 2. OPERATING CONDITIONS AND E
Page 257 and 258: i 1 \ ', References 1. 2. ( 3. 1 4.
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Page 261 and 262: t I 100 - - I I ] , I , I , I 'ii 9
Page 263 and 264: Feeding of the carbonaceous materia
Page 265 and 266: ! Table 2 Proximate and ultimate an
Page 267 and 268: lb, , --pp---p-- 4 p? CHAR 1 Tu-IWO
Page 269 and 270: I CHAR Y Y /I TIME O i ' ' ' ' 1 '
Page 271 and 272: could not be assumed constant. Thus
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Page 275 and 276: constructed and operated to demonst
Page 277 and 278: The experimental procedure for the
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Page 281 and 282: 1' TABLE 2 Screen Analysis of Sand
Page 283 and 284: n RECORDER I Ill I ’ NO. NOX THER
Page 285 and 286: \ 285 Y 0 I- 5 B 5 3 m "9 E5 3 uz 0
Page 287 and 288: CHAR1 TOC 0.85 M3/k 600 0 700 V 750
Page 289 and 290: f Durin all the experimental runs t
Page 291 and 292: Assuming that large coal particles
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Page 295 and 296: The influence of particle size dist
Page 297 and 298: all the initial values of x for whi
Page 299 and 300: \ - + 1) x. = 1 bL/n YO Defining di
Page 301: $ m. 1 Results and Discussion Evalu
Page 305 and 306: UNBURNT FRACTION UNBURNT FRACTION m
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