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

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The DTA/TGA studies o so im and potassium benzoate decompo . ition show that these model molecules initially decompose to form condensed ring organic molecules, alkali carbonate, and carbon dioxide. This initial decomposition process occurs over the temperature range of 400 to 600'C and is independent of the gas stream composition. Over this temperature range, there is no loss of alkali into the gas phase. Rather, all of the alkali is converted into the corresponding alkali carbonate. At higher temperature, the alkali carbonate decomposes and the course of this decomposition is determined primarily by the composition of the ambient gas. In an inert gas stream, the alkali carbonate decomposes over the temperature range of 700 to 900°C with release of carbon monoxide and atomic alkali. This decomposition has been confirmed by transporation mass spectrometer studies. l7 However, in a stream containing 20% Cop between 700 and 9OO"C, only carbon monoxide is released and the alkali is converted to alkali carbonate. This rection sequence occurs as long as residual carbon and carbon dioxide are present. Once the excess carbon has been converted to carbon monoxide, the alkali carbonate will decompose at temperatures in excess of 1200°C. Experiments were also performed with a combination of SOp, Cop, and O2 in the gas stream. Here, it was found that the alkali carbonate is converted to the alkali sulfate with no indication of alkali loss over the temperature range studied (< 1300°K). CONCLUSIONS Thus, the results of the measurements and experiments discussed above do provide a plausible way to begin an explanation for the distribution of alkali in che ash particulates. To summarize: 1. Under typical coal combustion conditions in an atmosphere rich in Cop and/or SOp, the alkalis in the organic fraction do not vaporize but remain bound in the ash as stable carbonates or sulfates. 2. The alkalis in the inorganic fraction diffuse to the surface producing enrichment by a factor of about 13 to a depth of about 100A. The results, however, do not provide conclusive evidence about the fate of the alkalis. The effect of water vapor in the combustion stream has not yet been studied. Clearly, water could have an important effect on the vaporization process. Furthermore, the reasoning we have followed to explain the absence of alkali enrichment in the submicron particles requires that the volatilization of the alkalis in both the organic and inorganic fraction not be significant (say less than 20%). 140
1, It is possible to make a reasonably clear statement about the alkalis in the organic fraction under various combustion conditions. Here, the volatilization of the alkalis is primarily determined by the heterogeneous chemical reaction of the alkalis with the gas stream. Such detailed information, however, is not available for the alkalis in the inorganic fraction. Here, experimental data were not obtained under appropriate conditions. Thus, the combustion experiments of Hims et al., which do show significant alkali vaporization, were performed in an O2 atmosphere without CO2 or SO2 enrichment. The experiments of Stinespring and Stewart, with the inorganically bound alkalis, measured only enrichment and did not study vaporization. The results of recent vaporization studies of Hastie et a1.18 were also not performed under conditions directly applicable to coal combustion. Clearly, a wider range of experimental data will have to be obtained. Specifically, the effects of surface chemistry on the alkali in the inorganic fraction will have to be studied before a more conclusive statement can be made about the fate of the alkali in coal combustion. ACKNOWLEDGMENTS This work was supported by the U.S. Department of Energy/Morgantown Energy Technology Center under Contract No. DE-AC21-81NC16244. REFERENCES 1. 2. 3. 4. 5. 6. 7. 8. 9. D.F.S. Natusch and J.R. Wallace, Science 186, 695 (1974). R.L. Davison, D.F.S. Natusch, J.R. Wallace, and C.A. Evans, Jr., Environ. Sci. & Technol. 8, 1107 (1974). J.M. Ondov, R.C. Ragaini, and A.H. Biermann, Environ. Sci. & Technol. 2, 947 (1979). D.G. Coles, R.C. Ragaini, J.M. Ondov, G.L. Fisher, D. Silberman, and B.A. Prentice, Environ. Sci. & Technol. 13, 455 (1979). L.E. Wangen, Environ. Sci. & Technol. 15, 1081 (1981). R.D. Smith, Prog. In Energy & Comb. Sci. 6, 53 (1980). R.W. Linton, A. Loh, and D.S.F. Natusch, Science 191, 852 (1976). J.A. Campbell, R.D. Smith, and L.E. Davis, Appl. Spectrosc. 32, 316 (1978). S.J. Rothenberg, P. Denee, and P. Holloway, Appl. Spectrosc. 2, 549 (1980). 141 - -
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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
Page 89 and 90: t 5360-096pj There is an interactio
Page 91 and 92: 1 I > \ i I 5360-096bw bed data. Be
Page 93 and 94: I 1. I 5360-096bw ranging from atmo
Page 95 and 96: uY.ku ICHlMAlIC OF MINI-FLUID BE0 R
Page 97 and 98: 800-12-1133 -9 FIGURE IO CALCULATED
Page 99 and 100: Mexico coal. Table 1 shows an analy
Page 101 and 102: ', Complete results from all runs c
Page 103 and 104: I the methanol down to atmospheric
Page 105 and 106: TABLE 3 -----______________________
Page 107 and 108: \ "I N z 107 c. . 0 0
Page 109 and 110: I. INTRODUCTION DIRECT METHANATION
Page 111 and 112: The catalyst development program fo
Page 113 and 114: Preparing process flow diagrams and
Page 115 and 116: \ \ i 1. 2,000 4,000 6,000 8,000 10
Page 117 and 118: (JMS-OlBM-2). The mass spectra were
Page 119 and 120: I I Fairbridge, R.W. (ed.) 1972, En
Page 121 and 122: v- W V z d 3 z m 4 ? P m W c3 W m N
Page 123 and 124: e. \ I , W 2 m 4 t- CI 99-79 noooo
Page 125 and 126: L Table I: Compositions of High Tem
Page 127 and 128: \ " \ I For all three coals, the pr
Page 129 and 130: 4 , 1024 1024 3a 3b J Mineral Parti
Page 131 and 132: The Determination of Mineral Distri
Page 133 and 134: pyrite crystals in framboids locate
Page 135 and 136: FIG. 1. TEM MICROGRAPH OF A HIGH VO
Page 137 and 138: \ \ FIG. 5. SEM MICROGRAPH SHOWING
Page 139: \ , species. In fact, combustion ex
Page 143 and 144: \ i SURFACE AND BULK ENRICHMENT OF
Page 145 and 146: I Coal Ash Sintering Model and the
Page 147 and 148: 5 carried out such sintering measur
Page 149 and 150: I this ash and other bituminous coa
Page 151 and 152: forming propensity. However, none o
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Page 155 and 156: CENTRAL ELECTRICIN RESEARCH LABORAT
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Page 159 and 160: temperature, sulfur species concent
Page 161 and 162: The facility is fired with coal usi
Page 163 and 164: Tests have been carried out to dete
Page 165 and 166: under which conditions sulfur speci
Page 167 and 168: I TITANIUM L Corn AS A TRACER FOR D
Page 169 and 170: E 6 i i h \ 1 1 \ on the XRF is cau
Page 171 and 172: \ ? CONCLUSIONS Titanium can accura
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Page 175 and 176: GFETC constructed a 0.2 square mete
Page 177 and 178: \: Stage 3. Sulfated ash-cemented a
Page 179 and 180: I FIG. 1. Initial ash coating on qu
Page 181 and 182: FIG 9. Limestone bed material alter
Page 183 and 184: (4) Since the operating temperature
Page 185 and 186: I I maximum particle diameter leavi
Page 187 and 188: ! suspension chambers and cyclone f
Page 189 and 190: 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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assumed to be identical to that of
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Nomenclature A *t cD ‘NO $3 _ _ _
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TABLE 2. OPERATING CONDITIONS AND E
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i 1 \ ', References 1. 2. ( 3. 1 4.
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\ ” Y) I 259
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t I 100 - - I I ] , I , I , I 'ii 9
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Feeding of the carbonaceous materia
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! Table 2 Proximate and ultimate an
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lb, , --pp---p-- 4 p? CHAR 1 Tu-IWO
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I CHAR Y Y /I TIME O i ' ' ' ' 1 '
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could not be assumed constant. Thus
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\ greatly acknowledged. Literature
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constructed and operated to demonst
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The experimental procedure for the
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atmospheric pressure fluidized bed
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1' TABLE 2 Screen Analysis of Sand
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n RECORDER I Ill I ’ NO. NOX THER
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\ 285 Y 0 I- 5 B 5 3 m "9 E5 3 uz 0
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CHAR1 TOC 0.85 M3/k 600 0 700 V 750
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f Durin all the experimental runs t
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Assuming that large coal particles
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i 7 -_ 0 m\o --n 0 W i 293 a\o 0
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The influence of particle size dist
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all the initial values of x for whi
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\ - + 1) x. = 1 bL/n YO Defining di
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$ m. 1 Results and Discussion Evalu
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kl k2 k' KC KD m m. m P N P R R g t
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UNBURNT FRACTION UNBURNT FRACTION m
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