INDUSTRIAL AND ENGINEERING CHEMISTRY
May 1949
TABLE11. MATERIAL BALANCE FOR GASES
TABLE I. HYDROGENATION OF B R U C ~ T O COAL N IN HYDROGEN AND IN COKEOVENGAS (1 hour a t temperature, 1.0% Sn Total ' Initial Pressure. Calcd ' Run Temp., Lb./Si. No. Vehicle C. Gas Inch C.0.G.a 2120 450 639 None Ha 1000 481 None 450 C.O.G. 1630 450 734 None 736 None Hz 830 450 C.O.G. 1650 H.0.b 450 657 C.O.G. 1610 658 H.O. 465 C.O.G. 1160 H.O. 450 659 C.O.G. 1120 H.O. 465 660 733 H.O. 450 Hz 870 H.O. 465 H.2 850 732 450 Ha 680 737 H.O. H.2 660 H.O. 465 736 a Coke oven gas. b Heavy oil.
+ 0.55% NH4C1) Initial Pressure of HI. Calcd., Lb./Sq. Inch 1170 1000 900 830 910 890 640 620 870 850 680 660
%
Liquefaction 86.3 86.1 75.2 86.0 73.5 51.7 62.3 25.8 85.4 75.1 79.2 54.8
Asphalt uer Unit Liquefaction 0.34 0.28 0.44 0.48 0.91 0.85 1.07 2.02 0.76 0.70 1.28 1.18
charged and bled were calculated; these weights, for runs 639 and 481, are listed in Table 11. The following items may be noted: The total weight of gas bled, as calculated from the volume and analysis of the gas, agrees well with that determined by direct wei hing of the bomb before and after bleeding. T%e decrease in carbon monoxide and increase in carbon dioxide in run 639 indicate that some of the carbon monoxide in coke oven gas undergoes the water-gas shift during the hydrogenation. The reaction CO 3Hz + CHI HzO does not occur appreciabl when coke oven gas is used. Etxylene in coke oven gas is hydrogenated to ethane.
+
Gas
Constituent H2 CHI CzH4 ClHS CaHa CaHs C4Hs CiHio CsHio CsHie N2
co coz
Air Total Total (direct weighing) Total hydrocarbon gases
Weight of Constituent, Calculated from Gas Analysis Run 639 Run 481 Charged, Bled, Change, Charged, Bled, Change, g. g. 8. g. g. g. 6.2 4.0 -2.2 5.5 4.2 -1.3 27.5 28.6 $1.1 0 2.1 +2.1 -0.Y 0 -0.9 0 0 0 3.9 +4.8 0 8.7 1.6 +l.6 0.2 '0.2 0 0 0 0 1.9 3.7 +1.8 0 1.5 +1.5 0.3 0.7 $0.4 0 0.2 +0.2 0.7 1.3 +0.6 0 1.0 +l.O 0 0.3 +0.3 0 0.3 +0.3 +0.3 0 0 0.3 0.2 +0.2 5.0 5.0 0 0 0 0 9.5 8.0 -1.5 . 0 0 0 +1.9 0 0.2 2.1 0.3 $0.3 0.8 0.8 0 0 0 0 57.i 63.7 +6.6 5 3 11.4 $.5.9 (57.1) 64.2 +7.1 (5.5) 11.2 +5.7 35.4
43.8
+8 . 4
0
6.9
$6.9
sure from 1630 to 1140 pounds per square inch does not appreciably influence gaseous hydrocarbon formation, increase in temperature from 450' t o 465' C. ( a t 1140 pounds per square nch initial pressure) almost doubles the gasification. ACKNOWLEDGMENT
Thanks are due to R. A. Friedel and his group for providing tho mass-spectrometric analyses of gases.
+
Similar gas balances have been made for runs 657, 659, and 660. The results are in agreement with the conclusions listed above. I n addition, i t appears that (1) the consumption of hydrogen is about the same in all the experiments (approximately 2 grams), and (2) although change in initial coke oven gas pres-
973
LITERATURE CITED
(1) Fisher, C. H., Sprunk, G. C.,Eisner, A., O'Donnell, H. J., Clarke, L., and Storch, 13. H., U. S. Bur. Mines, Tech. Paper 642 (1942). (2) Holroyd, R.,U. S. Bur. Mines, Information Circ. 7370 (1946). (3) Pott, A.,and Rroche, H., U. S. Patent 1,881,927 (Oct. 11, 1932), RECEIVED January 12, 1949. Presented before the Division of Industrial CHEMICAL and Engineering Chemistry at the 113th Meeting of the AMERICAN BOCIETY, Chicago, Ill. Published by permission of the Director, Bureau of Mines, U. S.Department of the Interior.
Mass Transfer in Liquid-Liquid Agitation Systems ARTHUR W. HIXSON AND MELVIN I. SMITH' Columbia University, New York 27, N . Y .
A procedure is developed which may be used to predict the quantitative performance of an agitator in a liquidliquid extraction system. An equation relating the weight of solute transferred from one liquid to a second immiscible liquid is derived; it is verified experimentally on the almost Ideal system water-iodine-carbon tetrachloride in a series of geometrically similar vessels. The numerical effect of speed of agitation upon rate of solute transfer is given.
T
HIS research is intended to extend the earlier work of Hixson and co-workers (1-4) into the realm of two-phase
liquid-liquid systems in which mass transfer occurs. The cube root law and its modifications, developed to describe the behavior "of solid-liquid systems in agitation vessels, are useful in the design -ofsuch agitators and as an index of the efficiency of such a vessel 1 Present
address, Socony-Vacuum Oil Qompany, Brooklyn, N . Y.
already in use. The purpose of this investigation is to derive a workable equation from theoretical considerations, to establish its validity experimentally, and to correlate the data obtained under various conditions in such a manner as to make feasible the design of an agitation vessel which will efficiently transfer a solute from one liquid to another. I n their work with solid-liquid systems, Hixson and eo-workers found the "dissolution constant" t o be a convenient index of the efficiency of agitation. This constant is a mass transfer coefficient in the true sense and is readily measurable. In this investigation of a liquid-liquid system, a hybrid coefficient is evolved which includes two mass transfer coefficients and the interfacial area of contact; none of these quantities lends itself to measurement. This new coefficient, easily determined, is a measure of transfer rate. I n the following derivation, the usual assumption of the existence of two films is made. I n addition, the interfacial area is
INDUSTRIAL AND ENGINEERING CHEMISTRY
974
assumed to be constant uridcr a given set of conditions. I n most systems the coefficient of the distribution of solute between the two liquid phases varies with concent,ration. If this variation m r e t,aken into considerat,ion, a mathematical approach to the problrm would be virtually precluded. I t is here treated as a, constant (or taken as a mean value). Finally, the liquids are taken to be immiscible, and equilibrium is assumed to ob,tain a t the interface. In ot’hcr words, an ideal system is assumed. The following derivation, starting with the usual rate equations, aims t o obtain a final form free of ina3s transfer coefficients and interfacial values. Considering transfer from R to E:
h‘n =
--
1
- + - Dkc 1
1 kR
--
+ DkL’
kR
Vol. 41, No. 5
W E ( I C ” - I
