INDUSTRIAL A X D ESGI-YEERI-VG CHEMISTRY
738
distillation have been determined experimentally and are given in Table 11. Values of p for intermediate rates were obtained by interpolation. of M a x i m u m Reflux w i t h Rate of Distillation 0 PRODUCT
Table 11-Variation p
-
7
Gram per second 0 025 0.040 0.065 0.075 0.085 0.100 0.115 0 150
0.85 0.80 0.75 0.70 0.65 0.60 0.55 0.45
p = -
RUN
9 10 11 12 13 14 15 16 17 18 19
Actual measured
0 I'
0.81 0.78 0.77 0.72 0.70 0.67 0.64 0.55 0.44 0.44 0.40
0.644 0.565 0,485 0.406 0.439 0.415 0.344 0.365 0.368 0.204 0.182
2-This height was found to be practically constant for variable reflux between p = 0.53 and p = 0.77, and for distillates up to 92.5 per cent alcohol. It was also found to be independent of the vapor velocity in the few cases where this quantity was varied greatly. 3-The effectiveness of a properly lagged Hempel column 99 cm. long provided with the maximum reflux is 2.4 to 41.5 times as great as that of the same column unlagged and operating a t the same rate of distillation. This improvement factor increases for low alcohol concentrations and high rates of distillation.
1
COMPOSITION
Max. used in calcn.
PRODUCT Product Gram/sec. 0.0354 0.0482 0.0566 0.0708 0.0744 0.0808 0.0894 0.1120 0.1530 0,1544 0 1845
fjq$$
Vapor in still
-
1-The height equivalent to a theoretical plate for alcoholwater mixtures, with a filling of beads 0.213 inch (0.541 cm.) average diameter, was found to be 3.92 inches (9.96 cm.).
-P e..r
I
1.0 4.2 0.2 4.2 3.7 2.9 1.9 0.3 2.2 2.2 n 4
..
r-. ent
10.1 42.2 2.4 42.2 87.2 29.2 19.1 3.3 22.1 22.1 4 1
10.0 2.4 41.5 2.4 2.7 3.4 5.2 29.3 4.5 11 1
,
0.8 3.1 0.2 2.8 2.4 1.9 1.0 0.3 1.0 1.0
nfi
By Marion Hollingsworth THE OHIO STATEUNIVERSITY, COLUMBUS, OHIO
9.95
Summary
SUMBER
RELATIVE IMPROVE- OF EFFECMEN+ PLATES TIVESESS FACTORAT TOTAL REFLUX
Protection of Iron Wire Used for Standardization'
9.95
= 2.7. Values obtained for improvement factor is 3.7 the unlagged column are tabulated in Table 111. The improvement factor reaches a very considerable value in some cases, being highest for low concentrations of alcohol. Other conditions remaining constant, the improoement factor would also vary with the length of the column. However, the authors have not considered it advisable to investigate columns of various lengths, as the object of the investigation is simply to develop a method for obtaining a n approximate estimate of the improvement effected in a laboratory column of average length. The values in the last column give a measure of the separation attained in terms of a common unit. The separation is low for high rates of distillation, as would be expected, although it is rather surprising to note that the range over which distillation takes place has a n even more marked effect on this quantity. It is evident that the separation attained in the short unlagged Hempel columns used in most laboratories would be even less than the figures given, so that in many cases the larger part of the observed separation would be due to simple rectification in the distilling flask alone. ' For sharp cuts such columns as those developed by Leslie3 or Peters4 are recommended. For the purification of quantities of material, however, the experimental column, described herein, suitably modified, would be equally effective. Comparatively large quantities of material might be easily handled by introducing the feed a t an intermediate point on the column and operating as a continuous still.
EQUIV. PLATES Max. REFLUX AT
(nl)
Per cent alcohol bv weight 68.0 32.2 3.9 90.5 77.3 47.9 26.9 14.0 1.9 89.6 74.1 34.0 89.7 80.3 62.5 89.3 82.6 69.6 82.2 69.6 23.0 58.0 46.6 6.2 86.8 82.0 67.4 84.0 74.7 35.1 77.5 69.0 2 1 .i
Taking Run 13 as an example, we have 0.0744 gram of product per second. This corresponds to a maximum p value of 0.70. The vapor entering the column was 80.3 per cent alcohol, and that leaving it 89.7 per cent. Substituting these values in equation (2) we find that this separation corresponds to 3.7 plates of a perfect column. Then the rela37 tire effectiveness is X 100 = 37.2 per cent, while the
Vol. 19, No. 6
T H E annoyance caused by the rusting and entangling of C. P. iron wire used for standardization purposes has led to the development of the apparatus shown in the accompanying sketch. For the ordinary '/d-pound spool of wire a wide-mouth bottle of 1.5 to 2 liters capacity is a convenient size. The metal strip, A , supporting the spool is about an inch wide, and contains holes as shown in the drawing, B being located opposite or, better, a little above the center of the spool. The strip is made so that it can be readily inserted with the spool through the neck of the bottle. A Iayer of lime, D, covers the bottom of the bottle. On top of this is a layer of cotton, E. The cotton and lime are held in position by a wire gauze, F , which in turn is secured by the spring, G. To make the disk of wire gauze easy to insert, imagine two parallel cords that will divide a diameter perpendicular to them into three a l m o s t e q u a l parts. Cut the gauze on either end of these cords, leaving about an inch for support. The gauze can then be folded on these cords, passed through the neck of the bottle, and again straightened. A test spool of wire kept for three years in such a container shows no sign of rusting. 1
Received March 4, 1927
