quenched gas were obtained without diluent and as high as 23.8 volume % (diluent-free basis) with 63.6% helium diluent. These acetylene concentrations are two to three times higher than any previously reported in the literature for reactions between the elements. Acetylene concentrations in the quenched gas greater than 147, and the increase in acetylene concentration with a n increase in diluent concentration support the proposal of Plooster and Reed (73) that C2H radicals exist in the hot gas mixture in appreciable concentrations. T h e high-intensity arc reactor proved to be far superior to the plasma jet reactor, induction furnace, resistance furnace, or combustion reactor for studying reactions between carbon and hydrogen a t high temperatures.
literature Cited
(1) Berthelot, M., Comfit. rend. 54, 640-4 (1862). (2) Bone, LV. A.: Jordan, D. C., J . Chem. Sac. 71, 41 (1897); 79, 1042 (1901). (3) Brewer, L., Searcy. A. \V., ilnn. Rer,. Phys. Chem. 7 , 259 (1956).
(4) Drowart, J., Burns, R. P., DeMaria, G., Ingram, M. G., J . Chem. Phys. 31, 1131 (1959). (5) Duff, R . E., Bauer, S. H., “Equilibrium Composition of the C / H System at Elevated Temperatures,” Office of Technical Services, LA-2556 (Sept. 18, 1961). (6) Finkelnberg, W., U. S. Dept. Commerce, Fiat Rept. 1052. (7) Gomi, S., “Direct Synthesis of CIHz from C H2,” S. M. thesis in chemical engineering, Massachusetts Institute of Technology, 1958. (8) Halpern: C., Ruegg, F. \V., J . Research A’atI. Bur. Standards 60, 29-37 (1958) ; Research Paper 2818. (9) Hiester, N.,“High Temperature Technology,” Symposium, Alisomar, Calif., October 1959, sponsored by Stanford Research Institute. (IO) Iwasyk, J. M.. “Carbon-Hydrogen System at Temperatures above 2500 O C.,” Sc. D. thesis in chemical engineering, Massachusetts Institute of Technology, 1960. (11 ) Kroepelin, H., Winter. E., ”Thermodynamic and Transport Properties of Gases, Liquids, and Solids,” ASME Symposium on Thermal Properties, McGraw-Hill, New York, 1959. (12) Margrave, J. L.. Ann. Rez.. Phys. Chem. 10, 459 (1959). (13) Plooster, M. N., Reed, T. B.. J . Chem. Phys. 31, 66-72 (1959). (14) Sheer, C., et al., “Investigation of the High-Intensity Arc Techniaue for Materials Testing.” Office of Technical Services. U. S. h p t . Commerce, WAD% TR 58-142, ASTIA 205,364; PB 161,265 (November 1958).
+
RECEIVED for review October 26, 1961 ACCEPTED March 5, 1962
ROLE OF THE PACKING IN A SCHEIBEL EXTRACTOR J. R. HONEKAMP’ AND L. E. BURKHART Institute Jor Atomic Research and Department oJ Chemical Engineerin,a t each packing height during every run. T h e r e s u l ~arc given in Table 11. From the analysis of variance, Table III? the continuous phase flo~vrate had no significant effect on outlet drop siie. The only significant effect of dispersed phase flow rate occurred Lyith the small inlet drops in Series F. At the high dispersed phase flow rate, inlet drops smaller than the characteristic size \\.ere produced, and these grew only slightly as they passed through the packing. Hence, the outlet drops \yere also smaller. If all of the droplets \\:ere of uniform diameter, the curves in Figure 3 for the 5 inches and 15 inches of packing would intersect on the 45' line shown. Intersection a t this point does not occur because a spectrum of droplet sizes was involved and becausr larger droplets are affected more than smaller droplets as they pass u p through the packing. An intersection could occur a t the theoretical point only in the case of a fortuitous distribution of droplet sizes. Standard deviation fclr the measurements in Series F \vas 0.13 mm. This value rereers to scatter in the average drop
1
d,,, M m . Continuous Phase Flow R X MI. /Sq. Cm. /hlin. 0 70 20
-
1
I1
c
2 3 10
1
I
3
2 3 20
1
I
I)
3 1
I1
D
2 3 20
1
11
D
2 3 10
1
1
F
2 3 20
1
I
F
1
I1
F
2 3 1
Ir
F
2 3 a
4' 50
2 2 2 2 2 2 2 2
36 98 36 98 95 85 52 31 26 28 92 45 56 48 16 44 79 14 34 37 36 14
2 2 2 2 3 3 2 2 2 2 2 4 2 2 2
44 42 24 27 42 21 52 33 39 16 82 00 66 35 12
2 3 2 2
56 00 52 '2
41
2 3 2 2 2 2
2 3 2 2 2 2 2 2 3 2 2 2 2 3 2 2 2 2 1 1 1 2 1 1 1 1 1 1 1
3
20
2 2 2 2 4
60 50 10
18 72 66
81 14 81 8' 42
1 36
2
10
38 42 18 04 98
2
2
10
2 2 2 2 3
57 40 64 52
1 '8 16 ' 1 96 1 95 1 83 1 48 1 70 1 52 1 77 1 -3 1 33
18
48 62
52 16 25 28 01 07 1 91 1 -6 1 '8 2 10 1 99
1 83 1 42 1 55 1 -4 1 45 1 60 1 -1
09
39 51 00
41 30 25 31 '9 72 27 36 11 08 68 75 l7
1 68 1 94 2 19
1 1 1 1
57
53 59
39
1 94
1 66
1 69 1 '4
1 80
2 26 1 -4 1 '5
1 91 1 85
1 -9
1 83
1 58
1 1 1 1
1 50 1 72 1 53 2 01 1 31
1 72 1 91 53 58 76 59 1 77 1 58
Duplicate runs no' madc.
VOL. 1
NO. 3
JULY
1962
179
Analysis of Variance for Drop Size Data on Packing
Table 111.
Series D Decrees of free.Wean square dom
Series C Decrees of Mean freeComponent dom square
1 2 1 2 5 2
Replicates
r’,
I .d c’l Vd
Error A Packing height Position I’c Position Vd Position
vc l’d
Error B Measurements Total 0
0 0 0 0 0 19
0045 0214 1320 0230 0272 1296‘
Of
0 0410
2 5 2
0 0118 0 0900 0 0089
4 2 4
0 0147 0 0350 0 0142
0 0358
12 36
0 0185 0 0169
12
0 0471
12
35 Signi’cant
h
1 2
0 0 0 0 0
0 0152
Signi’jcant at 7 70 level.
.Mean square
0.160 0 0179 0 0036 0 0254 0 0322 2 llOOa
4 2 4
35
freedam
1 2 1 2 5 2
4 2 4
0 0092 0 1877h
Series F Deqrees
1
0115 9613“ 0031 0165 1924‘1
Interfacial Area in a Four-Stage Scheibel Extractor.
-
71
at ,570 lecel.
Effect of Stirrer Speed o n Dispersed Phase Holdup
Table IV. Continuous Phase Flow Rate, Ml./Sq.
Total Column Holdup, % of I’oid Volume in Dispersed Phase Dispersed Phase Flow Rate. .Ml./Sq. C m /.Win. 6 5 7 7 5 3 5 24 15 32 90 41 50 50 50 R.P.M. Stirrer Speed,
Cm.,fiMin.
Replicate I
10.95
2 2 _2 3 4 2 2 2 3 4
0 400 600 850 1100 0 400 600 8 50 1100
21.80
10 31 87 _ 74 38 23 36 79 82 77
4 87 5 31 6 21 s.5 9 00 5 13 5 54 6 64 8 26 9 69
7
8 8 10 12 14 8 9 10 13 15
28 12 10 77 12 43 00 13 90 21 16 20 15 18 46 46 12 13 18 12 95 95 15 38 18 16 92 18 20 18
16 16 18 21 23 16 17 19 25 32
13 87 67 26 67 41 85 41 31 69
20 20
21 22 26 31 21 23 25 32 44
size from tbvo pictures taken a t the same position and includes errors in measurement, errors in sampling of drops from the pictures, and variations between the t\vo pictures. Five inches is the normal packing height between mixing sections in a commercially constructed 3-inch diameter YorkScheibel extractor. For the system investigated. 5 inches of packing was not sufficient for dispersed phase drops to reach the characteristic size. There was a significant difference between drops leaving 5 inches of packing and drops leaving 15 inches of packing. Drops rvhich entered the packing below the characteristic drop size gre\v a significant amount in passing through 5 inches of packing. However, a statistically significant amount of growth was less than 0.2 mm.
43 92
10 33 51 28 46 13 05
Steady state drop size a n d dispersed phase holdup were measured in a four-stage Scheibel extractor using the ketonewater system, with ketone dispersed. .4 factorial experiment with two levels of continuous phase flow rate: six levels of dispersed phase flow rate, and five levels of stirrer speed was used (Table IV). T h e experiment was replicated twice. Continuous phase flow rate. dispersed phase flow rate: and stirrer speed all produced significant effects on total column hold up. Standard deviation of the holdup measurements was 0.47, hold-up. Average drop size was measured in the second mixing section (Table V) immediately before the column was shut off for a holdup measurement. T h e average drop size in the mixing sections was below the characteristic drop size for the system. Since previous experiments had shown that very little gro\vth occurred in 5 inches of packing under these conditions, the average drop size was assumed to be the same in every mixing section.
1 50-
10.95
2 33 5 2 26 5 2 87 6 08 8 4 62 9 2 31 5 2 38 5 3 00 6 4 36 9 5 00 10
0 400 600 850 1100
21.80
4
0
400 600 8 50 1100
Table V.
MI. /Sq. Cm./Min.
8 92 10 51 13 05 1 4 61 8 59 9 28 10 90 13 49 15 41
12 13 16 18 12 12 15 18 20
43 90 05 72 31 95 28 46 77
16 18 21 24 16 17
72 49 28 23 67 44 20 25 25 28 32 64
21 24 27 32 21 23 25 33 44
d , , in M i x i n g Section, M m .
Stirrer Speed,
R.P.M. 0
400 600 850 21 80
8 46 12 05 16 03 20 51
74 15 77 59 97 07 54 15 72
Effect of Stirrer Speed on Average Drop Diameter in Mixing Section
Continuous Phase Flow Rate,
10 95
21 54 61 72 85 10 51 31 23 61
0
400 600 8 50
Dispersed Phase Flow Rate, M1. /Sq. C m . / M i n . 6.57 75.35 24. 15
2 24 2 07 1 27 0 90 2 19 2 08 1 56 0 72
2 10 1 69 1 75 0 59 2 73 2 04 1 36 0 86
2 21 1 76 1 54 0 78 2 39 1 79 1 51 0 92
I
I
I
40t
R.P.M.
dd.I
RP.M.
R.I?M. RP.M.
//
3%
f 3
5
6 7 8 910
I
I
I
I
20
30
40
50
SUPERFICIAL VELOCITY OF DISPERSED PHASE
l&EC PROCESS DESIGN A N D DEVELOPMENT
(cmhid
Figure 4. Total column holdup for continllox phase flow rate of 2 1 3 0 ml./sq. cm./min. Methyl isobutyl ketone dispersed in water
180
I
0 RPM.
400 600 t 850 v I100
A
0
Replicate II
I I l l
0
STANDARD DEVIATION
_J
Figure 5. Average $drop diameter in mixing section STIRRER SPEED
Methyl isobutyl ketone dispersed in water
Figure 6. Specific ircinsfer surface ratio in a four-stage Scheibel extractor
Ol 0
I
I
200
300
I 400
STIRRER
Methyl isobutyl ketone dispersed in water
Total column holdup data for the high continuous phase flow rate (Figure 4) show a sharp change in slope, indicating that loading occurred at high dispersed phase flow rates for stirrer speeds of 850 and 1100 r.p.m. Curves for the low continuous phase flow rate. 10.95 ml. per sq. cm. per minute, were the same shape with all points shifted down several per cent. Average drop size in the mixing sections during hold-up runs is shown in Figurle 5. T h e points are the average over the six different total flow rate combinations. Scatter indicated by the bracketii is inherent to the measurement technique and does not represent any effect of changes in flow rates. T h e specific transfer surface (i.e., interfacial area per unit volume of emulsion) was computed from Equation 2. Average drop size in the column was taken as the drop size in the mixing section because growth of the droplets as they passed through the packing was small. S = bH/d,,
I 100
(2)
These values of the specific transfer surface cannot be considered as the true mass transfer surface because they were obtained from an equilibrated system with no solute present. However, the ratio of specific transfer surface at any stirrer
(RPM.)
I
I
I
I
500
600
700
000
SPEED
(W.M.)
I
I
900
speed and flow rates to specific transfer surface a t zero stirrer speed and the same flow rates should be nearly the same with or without a solute present for many liquid systems. This statement is based on the assumptions that the only effect of the solute is to decrease the interfacial tension and that this decrease in interfacial tension would affect the drop size by the same amount a t all operating conditions. Figure 6 is a plot of the specific surface ratio for all flow rates and most stirrer speeds investigated. The ratio was independent of flow rates at stirrer speeds less than 600 r.p.m. At 850 r.p.m., it increased slightly with increased dispersed phase flow rate. T h e upper point in Figure 6 was the average value of the ratio for the three lower dispersed phase flow rates; the lower point was the average value of the ratio for the three higher dispersed phase flow rates. Concentration Profiles Along a Four-Stage Scheibel Extractor. Concentrations of both phases a t various points along a four-stage Scheibd extractor were measured using the sampling techniques described earlier. For all of these runs, a n aqueous feed of 20 wt. % acetic acid was used. T h e entering solvent was 0.20 wt. % acetic acid in methyl isobutyl ketone. T h e ketone was dispersed. Sample tubes, inserted into the packing 0.5 inch above and below each mixing section (Figure 7), protruded about 0.75 inch inside the column wall. VOL. 1
NO. 3 JULY 1 9 6 2
181
Column with sample tubes in place
Figure 7.
Thr column was operated for 30 minutes after the interface had become stationary before the sample tubes were opened. T h e sampling rate was approximately 0.5 ml. per minute through each tube. O n e hour after the interface had become stationary, the sample collection battles were changed and samples collected for the next 15 to 20 minutes. Product samples were taken again near the end of a run to be sure the column had remained near steady state while the internal samples were being collected. A typical concentration profile along the column is shown in Figure 8. Original data on concentration profdes are also available ( 4 ) . T h e points on this plot are the results of two identical runs. In most cases agreement was within 0.1 wt. %. At one time the column was completely disassembled, sample tubes removed, and new packing installed. T h e largest difference between the Concentration profiles before and after the column was disassembled was 0.60 wt. %. T h e irregular shape of the concentration profile in Figure 8, showing a large concentration change across the packing and a small Concentration change across the mixing section, is a result of axial mixing. Since the sample tubes were only 0.5 inch over and under the mixing sections, axial flow from the mixers reduced the concentration gradient across the mixing section. Channeling occurred at zero stirrer speed. New packing., installed in a n attempt to rectify this, merely shifted the channeling and did not correct it. When interpreting the concentration profiles, the points on these plots cannot be considered as the concentratiom of passing streams (i.e., operating points), since there is no indication of the direction of flow. Most probably, the streams a t the end of each pair of sample tubes were both flowing in the same direction because of the action of the mixers. The profiles do indicate the average concentration in the mixing section, This average Concentration was used to calculate the efficiency of the mixing sections from the following correlation developed by K a r r and Scheibel (7), in which the same liquid system was used in a geometrically similar mixing section:
T h e number of equilibrium contacts in the mixing sections Nas calculated from the concentration profiles and Equation 3 and converted to the number of transfer units by Equation 4. I n using Equation 4, the operating and equilibrium lines
...
L
2
-
4 6 8 10 IZ 14 10 WEIGHT PERCENT ACETIC ACID
1U
Figure 8. Concentration profile along a four-stage Scheibel extractor a t 400 r.p.m. with aqueous to organic flow rate ratio of 500/700 Methyl isobutyl ketone-acetic acid-woter system
182
I&EC PROCESS DESIGN AND DEVELOPMENT
0
400 600 850
_.
Wholecolumn Mixing section Packingsection Wholecolumn Mixing section Packingsection Wholecolumn Mixingsection Packingsection Wholecolumn Mixingsection Packing section
_r___
4.92 0 4.92 5.79 2.20 3.59 7.14 3 55 3.59 Flooded Flooded Flooded
2.20 0 2.20 4.13 2.24 1.89 4.72 3.73 0.99 5.65 4.18 1.47
2.72 0 2.72 3.66 1.71 1.95 4.23 3.15 1.07 5.05 3.65 1.40
4.19 0 4.19 4.52 1.60 2.92 5.12 3.00 2.12 6.15 3.50 2.65
1.47 0 1.47 2.11 1.64 0.47 3.15 3.02 0.13 3.67 3.55 0.12
40
-
20
-
0
Figure 9. Effect of stirrer speed on muss transfer in packed sections
0
I
I
I
I
I
I
100
200
300
I
I
0 COMBINED A COMBINED 0 COMBINED 0 COMBINED t COMBINED
400
500
I
FLOW FLOW FLOW FLOW FLOW
I
RATE RATE RATE RATE RATE
600
I
‘
I
700
000
+
I 900
STIRRER SPEED (R.PM.)
t COMBINED FLOW RATE COMBINED FLOW RATE
A
of Figure 10. Effect f stirrer SD ed on numb transfer units in packing (coriected for increased transfer area)
I
2000ml/mln 1666ml/rnln 1200ml/min. l000ml/min 8 3 3 mllrnin.
0
were assumed to be straight over the concentration range of one mixing section. This was a good assumption for the system investigated. 1 - 17,m (4)
T h e total number of transfer units in the whole column and in each section is listed in Table V I , for runs in Ivhich the concentration profile was measured. T h e total number of transfer units in the whole column was obtained from the customary yraphical integration based on the product concentrations, the curvature of the operating line being determined from a ternary concentration diagram. T h e total number of transfer units in the mixing sections was calculated as described above and the number of transfer units in the packing obtained by difference. I n Table \-I and Figure 9, no mass transfer is indicated in the mixing sections a t zero stirrer speed. A small amount probably did occur in the quiescent mixing sections, and this would tend to produce a y-intercept somewhat below loo’$& in Figure 9. T h e actual amount of transfer Lvhich did occur was not measured and hence not reported.
Discussion Drops below the characteristic size do not grow appreciably in 5 inches of packing height. Consequently, the average drop size in a n operating Schiebel extractor should be nearly
100
200
400 500 STIRRER SPEED
300
600
1000 r n l / r n i n 8 3 3 rnl/mln
700
000
900
(RPM)
constant after the first few mixing sections if the nonwetting phase is dispersed. LVith mass transfer taking place, a concentration gradient would exist from the top to the bottom of the column. This concentration gradient may affect the interfacial tension sufficiently in some systems to produce a changing drop size along the column. Under these conditions, the drop size a t any point along the column would be determinrd by the drop size in the adjacent mixing sections. T h e results of drop size measurements in Yorkmesh packing and hold-up measurements on the four-stage Scheibel extractor were compared with work on packed extraction columns (3, 8 ) . Drop size and hold-up in the Scheibel extractor a t constant stirrer speed closely paralleled a packed extraction column. Extraction data were compared M ith data of Trey bal ( 7 4 ) on a 3.55-inch diameter column packed with 0.5-inch Raschig rings. T h e packed column data were for the same liquid system with the nonivetting ketone phase dispersed and the solute transferred to this phase. T h e Scheibel extractor was more efficient than the packed column with this qstern. At \pry low flow rates and low stirrer speeds, the packed column was more efficient than the Scheibel extractor. However, there would be no advantage in operating a Scheibel extractor under these conditions. Figure 9 shows the per cent of mass transfer taking place in the packing. T h e initial decrease in packing performance from 0 to 600 r.p.m. was caused by increased axial mixing. VOL. 1
NO. 3
JULY
1962
183
Above 600 r.p.m., the transfer area increased faster than the axial mixing and the curves bent upward. T h e effect of the axial flow from the mixing section on the performance of the packing can be seen easily if the effect of increasing transfer surface is removed. T h e number of transfer units in the packing (Table VI) was divided by the appropriate value of the specific transfer surface ratio from Figure 6 and plotted in Figure 10. Thus, the values of NTU,, in Figure 10 a t any constant flow rate are all based on the same transfer area. T h e decrease in these numbers with increased stirrer speed must be attributed to a decrease in the transfer coefficient or the driving force. Since the increased stirrer speed would tend to increase the transfer coefficient, this over-all decrease in the NTU,, for the packed section must be d u e to a large decrease in driving force, the result of axial flow from the mixing section. Based on the results of this investigation, the following equation might be proposed as a basis for further work relating the number of transfer units i n a Scheibel extractor a t any stirrer speed and flow rates to its performance a t zero stirrer speed and the same flow rates. (NTUoL)v= (NTUm)oFaFmFk
(3)
This proposed equation would have two main advantages over correlations based on the performance of each section alone : T h e correlation techniques developed for packed extraction columns could be used to correlate the performance of the Scheibel extractor a t zero stirrer speed, and the errors involved in estimating the interactions between the two sections would be eliminated. A procedure for determining the specific transfer surface ratio (Fa)has been indicated in this report. T h e axial mixing factor (F,) could be expressed as a function of axial mass transfer Peclet numbers, as indicated by Miyauchi ( 9 ) . One method for evaluating this factor would be to employ a transient analysis such as that used by Jacqurs and Yermeulen (6) on packed extraction columns. Conclusions
With the equilibrated system of methyl isobutyl ketone and water, drops of the ketone phase below the characteristic size pass through 5 inches of Yorkmesh packing with very little increase in their average size. T h e behabior of a four-stage Scheibel extractor a t constant stirrer speed \vith respect to drop size and hold-up closel>parallels a packed extraction column. Approximately 25 to 50YGof the extraction, depending upon the operating conditions. takes place in the packing of a fourstage, 3-inch diameter Scheibel extractor with the system of methyl isobutyl ketone-acetic acid-water. I n the normal operating range, the mixers increased the transfer area and decreased the concentration gradient in the packed sections. T h e effect of increased transfer area M’ZS usually less than the effect of decreased concentration gradient, resulting in a n over-all decrease in the packing efficiency with increased stirrer speed.
184
I & E C PROCESS D E S I G N A N D D E V E L O P M E N T
A sampling technique was developed which can be used to obtain the concentration of solute in each phase of a dispersion. Nomenclature
- activity concentration, wt. 5; D = diameter of stirrer, in. d = diameter of sphere of equal volume of droplet, mm. d!, = Sauter mean diameter, mm. E = Murphree efficiency. 7G F = correction factor H = yG of column void volume occupied by dispersed phase m = slope of equilibrium line .v = stirrer speed, r.p.m. N T S = number of equilibrium contacts K T L = number of transfer units s = specific transfer surface, sq. cm./ml. flow rate, ml./sq. cm. min. height of mixing section, ft. ‘ip = average density difference in mixing section, grams/ ml u - interfacial tension, dvnes k m .
a
c
=
v z
= =
.
Subscripts a
= specific transfer surface ratio
C
=
d e k
= = = =
m S
= =
0
=
r
= =
1
o
continuous phase dispersed phase extract phase phase upon which N T C is based ratio of mass transfer coefficient a t .V stirrer speed to mass transfer coefficient a t zero stirrer axial mixing stirrer speed over-all raffinate phase zero stirrer speed
literature Cited (1) Bresee, J. C.. Chester, C. V., Proc. U. N. Intern. Conf. Peaceful Uses At, Energy, 2nd. Geneva, 1958. 20, 168-72. (2). Dallavalle. J. M.. “Micromeritics.” 2nd ed.. Pitman Publishing Co.. New York. 1948. (3) Gayler. P... Pratt, H . R . C., U. S. At. Energy Commission Rept. AERE CE/R-593,1951. (4) Honekamp. J. R., Research Notebook No. 60-42 HON-2, Ames Laboratory Document Library. ;\ma. Iowa. 1960. (5) Honekamp. J. R.. Ph.D. dissertation. Iowa State University. Ames, Iowa. 1960. (6) Jacques. G. L.. Vermeulen. T.. U. S. At. Energy Commission Rept. UCRL-8029, 1957. ( 7 ) Karr. A. E.. Scheibel. E. G.. ChPm. Eng. Prozr. .Ycmposiun2 Ser. 50, No. 10, 73-92 (1954). (8) Lewis, J. B., Jones, I.. Pratt. H. R. C.. U , S. A t . Energy Commission Rept. AERE CE/R-594,1951. (9) Miyauchi. T.. Ibid.;UCRL-3911, 1957. (10) Rodger. \V. A , . Ibid.,ANL-5575, 1956. ( 1 1 ) Scheibel. E. G., Chem. Eng. Progr. 44, 681 -90 (1948). (12) Scheibcl. E. G. (to Hoffman-La Roche Co.). U. S. Patent 2,493,265 (Jan. 3, 1950). (13) Treybal, R. E.. IXD.ENG.CHEM.47, 2435-6 (1935). (14) Treybal, R. E., “Liquid Extraction.” McGraw-Hill. Kew York, 1951.
RECEIVED for review August 17. 1961 ACCEPTEDJanuary 15. 1962. Contribution No. 948. M’ork was performed in t h e Ames Laboratory of the U. S. Atomic Energy Commission.
