Ind. Eng. Chem. Process Des. Dev. 1881, 20, 009-615
808
Reaction Model for the Dissolution of Large Particles of Texas Lignite Tuan-Chl Llu and Rayford 0. Anthony' Department of Chemical Engineering, Texas A&M University, College Station, Texas 77843
A model of 4 parameters was developed to predict the conversion of large, dry particles of Texas lignite as a function of pressure, temperature, and time. The same model can also predict the amount of gas produced during dissolution. The experiments were designed to approximate the conditions which might be encountered in solution mining of lignite, and data were obtained by using a 60-mL batch reactor at temperatures of 375, 400, and 425 O C and pressures of 21 to 130 atm. Solvents used for these experiments were tetralin, SRC recycled solvent, and creosote oil. The lignite charge was dried particles with a diameter of approximately 5 mm.
Introduction The kinetics of coal liquefaction have been studied by several investigators. Curran et al. (1967) treated coal liquefaction as two first-order reactions occurring in parallel. However, Gun et d (1979) believed that the reaction should be of a sequential nature. Brunson (1979) studied the kinetics of coal liquefaction in a flow reactor. He suggested a model by considering the coal as being composed of four different fractions. Each fraction reacts differently from the others. Hill et al. (1966) treated the coal liquefaction with first- and second-order kinetic expressions. Wen and Han (1975) fitted the rate data obtained by others with an empirical rate expression of the form r = kCAO(x,- x ) . Han and Wen (1979) considered coal liquefaction as a two-stage reaction. The initial stage requires little time to react, and a first-order reaction is proposed for this stage. In the second stage, hydrogen has to be supplied from the gas phase and the reaction requires long residence times. Other investigators, Given et al. (1975a,b), Cronauer et al. (19781, Shah et al. (19781, Shalabi et al. (1977,1979), Haley et al. (19801, and Anthony et al. (1980), have presented data and models on coal and lignite liquefaction. This study differs from the previous investigations in that the dissolution is conducted for a range of pressures from 21 to 130 atm. Large particles were used because the kinetic model and data were to be used to estimate the extent of dissolution which might occur in solution mining of deep basin lignite (Liu, 1980; Anthony, 1976). In the present study, a reaction model taking into account the pressure, temperature, and time effect on the lignite conversion as well as on the gas production is developed. Experimental Materials and Equipment A. Lignite. The lignite used for this research was furnished by Alcoa Co. at Rockdale, Texas. The freshly mined lignite chunks were stored in water to avoid air oxidation. A typical analysis is given in Table I. Before the experiment, the lignite was removed from the water and crushed to an average size of 5 mm. The lignite was then dried in air to a moisture content less than 1% . The mineral matter content of the lignite was determined by ashing in a furnace and found to be 15% on a dry basis. B. Solvents. The solvents were tetralin, SRC recycled solvent, and creosote oil. The tetralin was 99% pure product. SRC recycled solvent was obtained from the pilot plant at Wilsonville, Ala. The quality of the SRC recycled solvent varies from run to run. It is a mixture of many
Table I. Analysis of a Typical Sample of Texas Lignitea
A R ~ % moisture % ash % volatiles % fixed carbon
heating value, Btullb % carbon % hydrogen % nitrogen % sulfur % oxygen
22.29 12.73 33.95 31.03 8203 47.17 3.64 1.03 0.83 12.31
DB 16.38 43.68 39.94 10557 60.70 4.68 1.32 1.07 16.85
a Anal sis by Lignite Testing and Consulting, Bryan, Texas. AR: as received. DB: dry basis.
Table 11. Composition of SRC Recycled Solvent (Ellington, 1977) fraction low boiling tetralin naphthalene phenanthrenelan thracene high boiling
bp,"C
wt %
< 206
13 3 12 50
20 7 21 1 211-339 340 > 340
7 15
Table 111. Composition of Creosote Oil (Liu, 1980) components naphthalene 2-methylnaphthalene 1-methylnaphthalene biphenyl 2,6-dimethylnaphthalene 2,3-dimethylnaphthalene acenaph thene dibenzofuran fluorene methylfluorene phenanthrenelanthracene carbazole fluoranthene pyrene chrysene others light hydrocarbons (solvent)
wt%
9.9 1.3 0.8 0.5 0.3 0.5 2.7 1.5 3.3 0.6 9.3 2.8 3.5 3.2 0.6 8.1
51.1 100.0
components with most of the components being aromatics. An analysis reported by Ellington (1977) and presented in Table I1 showed that 50% of the solvent had a boiling point between 210 and 340 "C.
0196-43o51a11i 120-o~o9~1.2510 0 1981 American Chemical Society
610
Ind. Eng. Chem. Process Des. Dev., Vol. 20, No. 4, 1981 TO PRESSURE TRANSDUCER
Lignite
Reactor
Solvent
I Sandbath
I G WELD ED
I
50cm
--
n
-
/I
I 19cm
t
w------t I k--f
I
254cm
GC
I
h I
254cm OD 2 0 6 c m I D-
l4cm I
liquid 8 solvent
X
4.
Figure 2. Mini-reactor experimental procedure.
reaction time
quench In water
Figure 1. Mini-reactor.
The creosote oil used for this study contained 60% coal tar creosote, 38.5% petroleum hydrocarbons, and 1.5% water and free carbon. The hydrocarbons were light material and were used as a solvent for the coal tar creosote. A detailed analysis of the creosote oil is presented in Table I11 (Liu, 1980). C. Mini-Reactor. The reactor for studying the kinetics of the lignite liquefaction was a 60-mL batch reactor (Figure 1). The reactor was made of 2.54 cm 0.d. stainless steel tube with a transducer to record the reaction pressure. A sand bath was used to heat the reactor to reaction temperature. After the reaction, the reactor was quenched in water. The time required for heat-up was only 5 min and quench times were less than 10 s. The fast temperature response of the mini-reactor enabled a better definition of the reaction time at reaction temperature more accurately than the use of conventional autoclaves. The reaction temperature was assumed to be equal to the bath temperature. Previous experiments with thermocouples inserted within the reactor indicated that the reaction temperature was equal to the bath temperature within 5 min. The reaction times reported herein do not include the heating time. D. Experimental Procedures. A schematic diagram of the procedure is shown in Figure 2. Solvent and lignite were weighed and charged into the mini-reactor. After sealing and connecting the pressure transducer, the reactor was lowered into a fluidized sand bath. The bath was maintained at a constant temperature. The sand bath quickly heated the reactor to the reaction temperature. After a predetermined reaction time, the reactor was removed from the bath and then quenched in water. The reactor was not agitated. This could cause the particles to remain on the bottom of the reactor. However, this is the probable environment which would be encountered in solution mining. The gas product was released through a wet test meter where the volume of the gas was measured. The compo-
Time, minutes
Figure 3. Mini-reactor pressure curve.
sition of the gas was determined by a gas chromatograph. The slurry in the reactor after reaction contained the solid residue, the solvent, and the lignite-derived liquid. The slurry was then subjected to Soxhlet extraction with tetrahydrofuran (THF). The solid along with the thimble was air dried and weighed. The weight was later used for the calculation of the conversion.
Results and Discussion A. Experimental Results. The lignite conversions along with the reaction conditions are listed in Table IV. The weight of lignite includes 15% mineral matter and no water. The weight of the solvent charged to the reactor was 5 times that of the lignite charged. The purpose of using the high solventrblignite ratio (51 on dry basis) was to ensure that the lignite was surrounded by liquid solvent during the reaction. A low ratio of solvent to lignite could cause a substantial fraction of the solvent to be in the vapor phase at reaction conditions. Therefore, the reaction environment would be solid-vapor-liquid as opposed to solid-liquid. By subjecting the lignite to a consistent environment (submerged in liquid solvent) during dissolution, consistent results should be obtained. During the course of dissolution, gas was continuously produced. As a result, the reaction pressure, as illustrated in Figure 3, was continuously rising (since the reactor had a fixed volume). The pressures in Table IV are the maximum pressures recorded which were the final pressures. The difference between the maximum and initial pressures was usually less than 20%. The pressures were exerted by solvent vapor pressure, lignite-derived liquid vapor
Ind. Eng. Chem. Process Des. Dev., Vol. 20, No. 4, 1981 611
Table IV. Lignite ConversionsExperimental Data for Kinetic Analysis run no.
lignite,O g
solvent, g
T,K
P , atm
t, h
X1
0.25 0.50 0.75 1.00 1.00 1.00 1.00 0.25 1.00 1.00 1.00 1.00 0.75 0.50 0.25 0.25 0.50 0.75 1.00 1.00 0.67 1.00 1.00 0.75
0.406 0.536 0.624 0.624 0.677 0.746 0.814 (0.270) 0.448 0.536 0.550 0.503 0.478 0.435 0.360 0.595 0.754 0.799
0.03 8 (0.015)b 0.06 2 0.083 0.078 0.060 0.075 (0.082) 0.053 0.041 0.061 0.064 0.061 0.0 59 0.048 0.052 (0.094)
__ __ __
__
0.047 (0.027) (0.024) 0.051 0.081 0.056
(0.501) 0.557 0.573 0.599 0.533 (0.468) 0.442 0.349 0.426 0.466 0.439 (0.589) (0.784) 0.522
0.088 0.085 0,082 0.077 0.088 0.080 0.053 0.043 0.064 0.073 (0.081) 0.137 0.103 0.102
(0.300) 0.368 0.426 (0.41 2) 0.336 0.353 0.269 0.23 2 0.314 0.253 0.272 0.436 0.406 0.406 0.420 0.423
0.088 0.085 0.082 (0.106) 0.077 0.0 53 0.051 0.056 (0.055) 0.071 0.066 [0.236] [O. 1061 [O. 1371 [0.199] 10.1591
x,
A. Tetralin T1 T2 T3 T4 T5 T6 T7 T8 T9 T10 T11 T12 T13 T14 T15 T16 T17 T18 T19 T20 T21 T22 T23 T24
2.00 2.00 2.00 2.00 4.00 6.00 8.00 2.20 2.00 4.00 6.00 3.30 3.30 3.60 3.70 1.80 1.50 1.40 2.00 4.00 6.00 6.00 8-00 4.00
10.00 10.00 10.00 10.00 20.00 30.00 40.00 11.00 10.00 20.00 30.00 16.50 16.50 18.00 18.50 9.00 7.50 7.00 10.00 20.00 30.00 30.00 40.00 20.00
s1
2.00 4.00 6.00 8.00 4.00 4.00 4.00 6.00 5.00 4.50 4.80 3.00 3.20 3.00
10.00 20.00 30.00 40.00 20.00 20.00 20.00 30.00 25.00 22.50 24.00 15.00 16.00 15.00
2.00 4.00 6.00 2.00 2.00 2.00 3.90 3.60 3.00 3.30 3.20 1.00 2.00 1.80 1.60 1.70
10.00 20.0 0 30.00 10.00 10.00 10.00 19.50 18.00 15.00 16.50 16.00 5.00 10.00 9.00 8.00 8.50
s2 s3 54 55 S6 57 S8 s9 s10
s11
s12 S13 S14
c1 c2 c3
c4 c5 C6 c7 C8 c9 c10
c11 c12 C13 C14 C15 C16
29.57 30.59 31.61 32.63 4 5.90 65.29 130.59 24.18 25.49 35.69 49.98 30.93 33.65 3 2.29 32.97 35.01 34.67 35.69 25.49 3 8.4 1 39.78 49.98 101.68 49.98
673 673 673 673 6 73 673 673 648 648 648 648 648 648 648 648 698 698 698 673 673 673 673 673 6 73
B. Wilsonville-SRC Recycled Solvent 21.41 6 73 1.00 33.65 673 1.00 52.02 6 73 1.00 70.39 6 73 1.00 35.01 6 73 0.75 32.63 673 0.50 31.61 673 0.25 34.33 648 0.25 33.65 648 0.50 32.29 648 1.00 31.61 648 0.75 32.63 698 1.00 32.63 6 98 0.50 34.33 698 0.25 C. Creosote Oil 30.93 673 44.88 673 69.71 673 31.61 673 29.57 6 73 28.21 6 73 34.67 648 35.69 648 30.25 648 33.65 648 33.65 648 27.53 698 34.33 698 35.69 698 34.33 698 32.29 698
1.00 1.00 1.00 0.75 0.50 0.25 0.25 0.25 1.00 0.50 0.75 1.00 0.25 0.50 1.00 0.75
_-
__
___
a Dry lignite charged; ash content is about 15% of the weight. The data in the parentheses () are considered with large errors and will not be used to determine the model parameter. This treatment is suggested by Himmelblau (1970). The data in the brackets [ 3 are not used to determine the parameters because of the decomposition of creosote oil at 698 K which causes excessive gas production.
pressure, and pressure of the gas product. Since the amount of gas being produced is a function of the amount of lignite charged, the reaction pressures can be controlled by the amount of lignite charged. All the experiments were controlled at pressures below 130.59atm, with most of the runs between 20 and 70 atm. Three temperatures were used and there were four different reaction times (except run T21). The conversions were calculated on a moisture and mineral matter free basis and are generally referred to as moisture ash free
basis (MAF). The lignite conversion was calculated by using the equation x1 =
lignite charged - residue lignite charged X 0.85
(1)
The 0.85 factor is to correct for the mineral matter present in the lignite charge. Hence, the denominator is the weight of lignite charge excluding the moisture and mineral matter. Both terms in the numerator contain mineral
812
Ind. Eng. Chem. Process Des. Dev., Vol. 20, No. 4, 1981
Table V. Composition of Mini-Reactor Gas Product
v, H,S
n-C,b
mLc
Md
ge
0.00
0.00 0.00 0.10
0.00 0.00 0.00 0.11 0.13 0.00
1.18 1.17 0.78 1.38 0.81 0.75 0.84 0.24 4.94 0.48 0.55 0.79 0.94 0.30 0.57 1.42 1.85 1.77 0.92
0.00 0.00 0.11 0.33 0.35 0.20
46 17 76 108 198 227 368 85 57 85 198 113 102 110 91 57 99 424 76
40 37 34 32 33 33 34 40 22 39 38 40 40 41 41 35 29 28 25
0.07 0.03 0.11 0.14 0.26 0.31 0.51 0.14 0.05 0.14 0.31 0.18 0.17 0.18 0.15 0.08 0.12 0.49 0.08
9.56 8.95 7.76 0.00 7.64 7.43 0.00 5.68 0.00 3.55 0.00 0.00 0.00 1.72 0.00 0.00 3.23 0.00 2.38 0.18 13.93 0.39 11.73 8.23 0.54
B. Solvent: SRC Recycled Solvent 23.08 7.14 5.31 1.20 0.53 22.18 6.49 4.89 0.82 0.48 22.64 6.15 3.54 0.44 0.33 24.68 6.25 2.00 0.20 0.16 19.41 6.57 3.79 0.69 0.37 16.23 7.32 2.95 0.66 0.27 12.09 8.30 1.85 0.56 0.14 6.69 8.45 0.57 0.21 0.00 8.15 7.30 0.88 0.24 0.06 7.06 11.52 1.79 0.40 0.13 9.94 6.91 1.37 0.33 0.09 31.01 4.78 8.16 1.01 0.86 27.60 6.25 5.69 1.22 0.57 20.60 7.89 4.03 0.92 0.38
0.85 1.15 1.01 0.31 1.55 1.51 1.59 0.92 0.95 1.59 1.09 1.81 1.22 1.27
1.26 1.05 0.65 0.29 0.82 0.58 0.32 0.00 0.10 0.27 0.20 2.14 1.36 0.86
108 207 309 382 212 184 113 133 164 176 207 292 218 190
33 34 33 33 35 36 38 41 40 39 39 29 31 34
0.15 0.29 0.4 2 0.52 0.30 0.27 0.18 0.22 0.27 0.28 0.33 0.3 5 0.28 0.26
1.04 5.33 0.62 5.74 5.59 0.00 4.73 1.43 3.53 0.79 1.35 0.00 0.00 0.00 1.18 0.00 1.62 1.89 0.00 1.09 0.00 0.00 2.06 10.38 2.29 9.60 1.66 8.56 1.38 10.25 1.95 12.54
C. Solvent: Creosote Oil 13.83 10.99 3.55 1.41 16.43 9.84 3.55 0.91 17.60 7.29 2.78 0.45 14.40 15.96 2.11 0.85 12.85 19.26 2.08 0.93 9.41 15.67 1.64 1.68 6.13 12.61 0.00 0.00 6.17 13.40 0.45 0.40 8.32 14.93 0.93 0.55 8.33 15.48 0.81 0.55 8.72 13.26 1.33 0.81 18.14 10.39 6.79 2.67 17.55 12.29 5.80 2.43 15.58 9.53 4.61 1.67 16.86 6.83 7.89 2.59 21.44 9.82 7.85 2.68
0.76 1.10 0.69 0.48 0.85 1.26 0.00 0.15 0.17 0.55 1.15 0.64 0.77 0.21 1.07 0.68
0.70 0.66 0.45 0.36 0.31 0.26 0.00 0.00 0.12 0.00 0.00 1.72 1.46 0.98 2.19 2.14
96 198 283 113 85 57 102 105 85 125 113 142 127 142 184 170
37 36 36 36 36 38 40 40 39 39 39 34 34 36 36 33
0.15 0.29 0.4 2 0.17 0.13 0.09 0.17 0.17 0.14 0.20 0.18 0.20 0.18 0.21 0.27 0.23
H,
CO,
C,H,
C,H,
T1 T2 T3 T4 T5 T6 T7 T8 T9 T10 T11 T12 T13 T14 T15 T16 T17 T18 T19
0.20 5.30 10.34 15.50 13.88 11.99 9.81 0.00 3.50 2.74 3.63 1.51 0.88 0.17 0.00 7.08 18.89 22.86 29.03
77.28 68.79 59.43 57.15 58.73 59.60 62.27 78.70 0.00 78.43 77.11 79.94 80.30 82.80 8 2.90 62.61 44.65 42.87 38.47
0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
0.00 0.00 2.48 2.70 3.15 3.25 3.72 0.00 0.00 0.23 1.06 0.00 0.00 0.00 0.00 3.08 4.75 5.08 4.72
4.11 4.44 5.06 4.68 3.65 2.18 0.37 0.00 0.06 0.26 0.12 7.59 5.97 3.87
46.96 49.55 52.42 53.79 55.72 62.62 71.23 83.16 80.54 73.75 77.57 28.53 38.00 51.85
0.21 1.64 1.60 0.37 0.28 0.00 0.00 0.00 0.00 0.00 0.00 3.01 2.84 1.06 2.50 2.75
61.86 59.48 63.29 59.15 58.99 68.73 81.26 78.25 71.42 73.19 74.73 43.54 44.41 55.77 47.59 37.27
s1
s2 s3 s4 s5 S6 s7 S8 s9 s10
s11 s12 S13 S14
c1
c2 c3 c4 c5 C6 c7 C8 c9 c10
c11
c12 C13 C14 C15 C16
w,
i-C4=
run
0.00 0.00 0.00 0.19 0.00 0.00 0.00 0.00 0.00
CH,
CO C,H, C,H, A. Solvent: Tetralin 8.17 12.18 0.73 0.26 11.20 11.97 1.04 0.35 11.60 13.86 1.10 0.31 11.75 10.41 0.90 0.21 9.05 1.12 0.14 12.98 14.11 9.00 1.09 0.08 6.55 15.55 1.09 0.05 5.80 12.47 1.51 0.89 42.19 45.78 3.05 0.54 7.90 9.70 0.42 0.10 8.06 9.06 0.46 0.07 7.53 9.64 0.48 0.11 7.16 10.18 0.41 0.13 6.06 10.26 0.31 0.10 5.03 11.27 0.18 0.05 12.06 11.59 1.52 0.53 15.51 10.85 2.25 0.62 2.29 0.55 15.06 9.04 15.72 8.54 1.93 0.47
0.00 0.00 0.00 0.04 0.04 0.04 0.07 0.00 0.00 0.00 0.00 0.00
0.32 0.33 0.26 0.16 0.13 0.00 0.00 0.00 0.05 0.00 0.00 0.66 0.56 0.37 0.85 0.88
0.00 0.10 0.09 0.08 0.32 0.00 0.00 0.00 0.00 0.00
Isobutane. n-Butane. Volume of gas production measured by wet test meter at 1 atm and 298 K. molecular weight. e Weight of gas production.
matter. Assume that the mineral matter cannot pass through the pores of the thimble during the Soxhlet extraction; then both terms of the numerator contain the same amount of mineral matter. The difference, therefore, is the amount converted (MAF). The lignite conversion calculated by eq 1 includes the lignite converted to both gas and liquid products. Also, the lignite conversions in Table IV are for using THF to extract the residue. The product gas composition determined by gas chromatography and reported in Table V was used to calculate the average molecular weight as N
M = CMiyi i=l
(2)
where yi = mole fraction of component i and Mi = molecular weight of component i. With the measured volume
Average
of the gas, V , and the average molecular weight, M,the weight of the gas product is calculated by MPV = (3) RT where R = gas constant, P = 1 atm, and T = 298 K. The conversion of lignite to gas, x,, is calculated by
w,
xg =
~
w,
(4) lignite charged X 0.85 B. Kinetic Modeling. Following the equation proposed by Wen and Han (1975),the rate equation is expressed as dx1 - = k(xl, - XI) dt
Ind. Eng. Chem. Process Des. Dev., Vol. 20,No. 4, 1981 613
Table VI. Estimated Parameters solvent x b o" A', atm-' tetralin SRC creosote
A. For the 0.65 0.55 0.34
10
B, K
Conversion of Lignite 4547 2 . 6 3 ~10-3 3476 2.25X 4.80X 3873
k,h-' -0.8
4.4 7 6.18 11.77
B. For the Conversion of Lignite to Gas 2863 tetralin 0.070 5.07 X -4.31 X 5713 SRC 0.096 2394 -6.34 X creosote 0.086
4.28 3.52 4.51
/I
c
I
c
._ ? 06
z
8 0
a 04
4-
.-0
e
Lz
Maximum conversion at 673 K and 32 atm.
Where xh is the maximum conversion that can be obtained at a given set of pressures and temperatures. The above equation assumes a first-order reaction with k as the reaction constant. Upon careful examination of the data in Table IV, the dependence of x h on P and T can be adequately represented by
(+)
0 crcrotc 011
02
, AT T
(7) Equations 6 and 7 are similar to those used to expressed the pressure and temperature effects on equilibrium quantities (Denbigh, 1971). By integrating eq 6 and 7, substituting the result into eq 5, then integrating and rearranging eq 5, eq 8 is obtained x1 = x d e [A'(P-PO)-B((~/T)-(~/TO))I)(~ - e-kt) (8) where xho = maximum lignite conversion at (Po,To), A' = A/To, Po = reference pressure = 32 atm, and To = reference temperature = 673 K. There are four parameters, xho, A', B, and k, in eq 8. These parameters are to be determined from the experimental data (Table IV). A Statistical Analysis System (SAS) nonlinear regression program was used for this purpose. A common practice of selecting Po is that Po is the most frequently occurring pressure in the experimental data. Similarly, Tois also selected. In our case, Po= 32 atm and To= 673 K. The rate equation for the conversion of lignite to gas was assumed to be of the same form as eq 8 and the parameters were fit by using the SAS analysis. The parameters are shown in Table VI. The value of xho is the maximum lignite conversion at the reference state-32 atm and 673 K. From the estimated xho, tetralin appears to be the best solvent, followed by SRC and creosote oil. However, for the amount of gas generated during the liquefaction, the order becomes SRC > creosote oil > tetralin. Therefore, the conclusion is that using tetralin as a solvent for liquefaction results in the highest lignite conversion and the lowest gas production when compared to the other two solvents. This result is
0
0
02
04
06
08
10
Experimental Conversion, XA
Figure 4. Scatter plot of lignite conversion.
to be expected since the hydrogen donor capability of the solvents is tetralin > SRC > creosote. The value of A'represents the effect of pressure on the conversion. A negative value means that a higher pressure yields a smaller conversion. A positive value means the opposite. The magnitude of the pressure effect is determined by the absolute value of A'. The values in Table VI suggest that the lignite conversion increases with increasing pressures for all three solvents. For SRC or creosote oil, increasing pressure decreases xr However, when tetralin is used, gas production increases with increasing pressure. The temperature effect is expressed by the value of B. Since the estimated values of B are all positive, increasing temperature increases conversion. As in the case for pressure, the magnitude of the effect is determined by the magnitude of B. The rate constant, k, was found to be temperature independent in this investigation. Physically, this suggests that the lignite dissolution is controlled by mass transfer (Holland and Anthony, 1979). This phenomenon could be a result of not agitating the reactor and using dry and large (5 mm) lignite particles (Anthony et al., 1980). However, the solvents exert a definite influence on this parameter which would not necessarily be expected for rates controlled by mass transfer. The special k (= 11.77) for the conversion of lignite when using creosote oil as solvent is worth noticing. The miscellaneous experiments with and without solvents that are listed in Table VI1 indicate that conversions obtained by using creosote are approximately equal to conversions obtained without solvent. Hence, when using creosote oil as a solvent for dissolution, only a devolatization of lignite occurs. That is, creosote oil as suspected does not show any solvent power. C. Goodness of Fit. Equation 8 and the parameters in Table VI are used to predict the conversion a t a given
Table VII. Miscellaneous Mini-Reactor Experiments lignite,c g solvent solvents, g P,atm T,K 27.5 648 1.0 0.368 0.071 4.00 d 39.13 0.360 0.065" 0.00 1.0 90.8 6 73 20.00 none 1.0 0.318 0.090 32.6 6 73 5.00 none 0.00 0.435 0.094 86.0 700 1.0 12.75 none 0.00 0.320 0.078 33.7 6 73 5.00 water 0.75 1.0 0.344 0.097 5.00 50.7 6 73 1.0 water 1.50 __1.0 298 5.00 0.031 0.000 e 0.00 0.4 24 0.130 1.00 40.5 673 f 10.60b 2.00 Dry lignite particles ( 5 mm diameter) were charged to Slight leak observed. Creosote oil ( 1 0 g) and water (0.6 9). the reactor. Anthracene oil. e Soxhlet extraction. f Creosote-water. run no. A1 B1 B2 B3 w1 w2 BB1 CW1
614
Ind. Eng. Chem. Process Des. Dev., Vol. 20, No. 4, 1981
Table VIII. run eb % T1 -6.7 T2 -7.5 T3 -0.6 T4 -3.1 T5 1.4 T6 6.2 T7 -2.4 T8 T9 -8.1 T10 7.1 T11 5.8 T12 1.7 T13 -1.7 T14 -3.0 T15 6.4 T16 5.8 T17 1.1 T18 -1.1 4.1
(6)
Errors of Estimated Conversions run el, % eg, % run -17.6 91 -9.4 c1 - 91 1.2 -7.7 c2 - 53 -0.1 -3.7 c 3 -8.1 54 0.2 -2.1 c4 19.7 S5 -2.7 0.4 c 5 -14.9 S6 1.4 C6 2.8 57 2.4 -5.4 c 7 - 58 -2.0 7.8 C8 -9.6 S9 -1.2 13.0 c 9 -30.5 S10 3.6 9.3 c 1 0 2.7 S11 -1.5 - c11 8.9 512 9.3 c12 6.5 S13 - -3.7 C13 - - C14 12.1 S14 -0.1 1.5 6.1 C15 22.4 (Z1) ( F g ) C16 -3.2 eg, %
-
el, %
eg,%
-
3.8 0.1 1.1 2.9 -0.9
-
-
-1.3 0.2 9.9 -8.8 1.3 1.1 -13.1 11.1 14.4 -9.2 2.7 -2.5 -8.4 5.0 -0.1 -5.8 -2.1 -0.5 4.9 4.2
12.2
(e,) 0 12
/I
0 10 m
