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

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i- s - I 9r 8 7 6 55 D: z y 4 3 2 1 1.0 2.4 3.7 6.0 18 I PARTICLE DIAMETER (10'6fl) 1 2 3 4 5 PARTICLE DIAMETER (10% Flgurs 2. Lilrlclmesr vs. Yorflclr Size. Baaed on Data by BmLt11. Pmg. Energy and Comb. scl.. a. SI (1980). 144
I Coal Ash Sintering Model and the Rate Measurements E. Raask Central Electricity Research Laboratories Kelvin Avenue Leatherhead, Surrey, UK INTRODUCTION In spite of innumerable laboratory investigations and the wealth of practical experience, there remains some enigmatic facets in the formation of sintered ash and slag deposit on heat exchange surfaces in coal-fired boilers. That is, occurrences of massive build-up of ash deposits can take boiler design and operation engineers by surprise. This would suggest that the engineers are receiving incomplete or incorrect information on the deposit-forming propensity of ash in different coals. Traditional methods of assessing the behavior of deposit-forming impurities in high temperature boiler plants are based on ash fusion tests as described in different national standards for coal analysis and testing, e.g., ASTM (1968), British Standard (1970), DIN (1976) and Norme Francaise (1945). These ash fusion tests have been developed from refractory material technology, and are based on observations of the change in shape and size of an ash sample on heating. It has been realized that the results of ash fusion tests are frequently imprecise, and can lead to a mistaken assessment of the likely severity of boiler fouling and slagging. There has been a number of suggestions made for ash fouling and slagging indices to predict more accurately the rate of deposit build-up with different coals as reviewed by Winegartner (1974). The empirical formulae, e.g., silica ratio, basic to acidic oxide ratio, and sodium and sulphur contents of coal, are based on the chemical analysis and have a limitation that they apply to particular coals. That is, there is no universal formula of predicting the severity of boiler fouling based on ash fusion tests and chemical analysis with all types of coal. It is therefore evident that further research is necessary on the mechanism of ash particle-to-particle bonding at high temperatures. This work sets out to redefine an ash sintering model in terms of measurable parameters, surface tension, viscosity, electrical conductance, temperature, particle size and time. In the experimental work, novel methods of measuring the rates of ash sintering were applied, in order to test the validity of the sintering model. SINTERING MODEL Frenkel (1945) has derived an equation relating the growth of the interface between two spherical particles: where x is the radius of the interface, r is the original radius of the spheres, Y is the surface tension and t is the time. Rearranging the equation in terms of x/r and t, it becomes: and it is applicable when < 0.3. 145
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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
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 and 140: \ , species. In fact, combustion ex
Page 141 and 142: 1, It is possible to make a reasona
Page 143: \ i SURFACE AND BULK ENRICHMENT OF
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
Page 157 and 158: 157 18 I I a I
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
Page 173 and 174: NY) m * oa
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
Page 191 and 192: After the fiscal year 1982, the fol
Page 193 and 194: 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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the coking properties of coal at elevated pressures. - Argonne ...

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