Packing Material for Fractional Distillation Columns C. 0.TONGBERG,' S. LAWROSKI, AND M. R. FENSKE The Pennsylvania State College, State College, Pa.
A
the subsequent condensate spreads uniformly over the entire wet surface; on a dry packing the flow of condensate tends to be somewhat agglomerated or coalesced. This effect is usually greater with the more efficient packings but is probably true of all packing materials. Thorough wetting of the packipg is best accomplished by deliberate flooding of the column a t the start of the distillation or test. Pouring the material to be distilled down through the top of the column has not been found as effective. This new packing was tested in two different columns. Each column was made of glass and had an inside diameter of 0.79 inch (20 mm.). The stillheads were the regular type used in the research laboratories here. The height of packed section for the first column was 23.5 inches (60 em.) and for the second 111inches (282 cm.). The test liquid was a binary mixture of n-heptane and methylcyclohexane; alpha = 1.07 (1). All tests were a t total reflux. Whenever possible the original concentrations of the two components were chosen so that neither the distillate nor the still would be too rich in one component when equilibrium was established. Because of the difficulty of analysis, errors of considerable magnitude may develop if the still is too rich in methylcyclohexane or the distillate too lean. The rate of distillation was measured by opening the take-off stopcock and timing the condensate
SINGLE-TURN helix packing material for distillation and extraction work was developed in this laboratory and found to have excellent efficiency and throughput (2, 3, 4, 6). The helixes were usually made of No. 26 B. & S. gage wire in sizes froms',1 to inch (3.2 to 6.4 mm.) i. d. The efficiency increased and the throughput decreased as the inside diameter of the helix was decreased. Helixes made of No. 30 B. & S. gage wire, with an inside diameter of s/3z inch (2.4 mm.), have now been tested. The results show this packing material to be more efficient than any other used in this laboratory and yet to have a good throughput. These S/32-inch diameter helixes exhibit to a marked degree a peculiarity found previously in other packings (5)-namely, a relation between efficiency and dryness of the packing prior to testing. The number of theoretical plates realized is much greater if the test is started with the packing thoroughly wet rather than dry. Apparently when the packing is first wet, Present address, Standard Oil Development Company, Elizabeth, N. J.
1
I. EFFICIENCIES OF '/SZ-~NCH SINGLE HELIXESI N A COLUMN WITH 0.79 INCH INSIDE DIAMETER AND 23.5 INCHES OF PACKED SECTION vn nf __
TABLE:
Test No.
Time ' between Rate of 7-n-HeptaneTests Boiling Distillate Still Hours Ce./hr.a Mole per cent
Theoretical Plates in Column H. E. T. P.6
In.
Cm.
1.7 2.0 1.95 1.9 1.6
4.3 5.1 5.0 4.8 4.1
1.3 1.25 1.05
3.3 3.2 2.7
TABLE11. EFFICIENCIES OF s / s z - I SINQLE ~ ~ ~ HELIXESIN A COLUMN WITH 0.79 INCH INSIDE DIAMETER AND 111 INCHES OF PACKED SECTION
Column Started with Packing Dry 1
2 3 4 5
4 1 2 2 2.5
430 430 690 780 750
6 7 8
2.5 2 2.5
785 720 340
54.2 51.4 50.5 51.4 53.0
31.2 32.3 31.2 31.0
29.5
14.0 11.5 12.0 12.5 14.5
Test No.
Column Deliberately Flooded
55.5 56.0 60.3
27.3 27.0 25.5
18.0 18.5 22.0
1 2
Column Shut Down and Let Stand Overnight to Dry Packing; Restarted and Deliberately Flooded
9
lo 11 12 18
3.5 4 2 2 5
13500 800 300 360 1140
54.7 54.9 62.3 61.7 53.6
29.0 27.3 27.0 26.2 24.9
16.0 17.5 22 0 22.5 18.5
1.45 1.35 1.05 1.05 1.25
4 1.5
600 780
55.5 56.8
29.5 28.7
16.0 17.5
1.45 1.35
3 4 5 6
3.5 2
750 750
55.2 58.7
29.2 29.0
16.0 18.5
1.45 1.25
3.7 3.4
5.5
880
60.6
27.6
20.5
1.15
3.7 3.2
2.9
a b c
4
940
50.0
27.6
14.5
1.6
15.5 15.5
58 57
1.9 1.9
4.9 4.9
6 2 5 5
1260 1260 660 280
95.8 97.4 97.2 96.9
7.4 5.0 3.7 3.4
84 97 100 100
1.3 1.1 1.1 1.1
3.4 2.9 2.8 2.8
8 9 10 11 12
1: 6 7
8
13
9
880 900 900 1020
70.4 68.6 67.4 63.0 58.0
14.0 10.5 10.5 6.6 6.6
39 43 42 47 44
2.8 2.6 2.6 2.4 2.5
7.2 6.6 6.7 6.0 6.4
79.9
2.2
77
1.4
3.7
1000 Column Deliberately Flooded
920
Column Shut Down to Allow Packing to Dry; Restarted and Deliberately Flooded
Column Shut Down and Let Stand Oyernight to Dry Packing; Restarted with Packing Dry
20
90.3 89.6
Column Shut Down t o 4110w Packing to Dry. Reetarted with Fresh Binary Solution and Packinh- Dry -
Column Shut Down and Let Stand Overnight to Dry Packing; Restarted and Deliberately Flooded 2.5 800 60.6 27.6 20.5 1.15 2 9
19
1200 120
Column Shut Down to Allow Packing to Dry; Restarted with Packing Dry 7 6 770 60.9 4.8 51 2.2 5.5
Column Shut Down and Let Stand Several Days: Restarted and Deliberately Flooded
16 17
4 5
Column Shut Down and Left Overnight to Dry Packing; Restarted and Deliberately Flooded
3.7 3.4 2.7 2.7 3.2
Column Shut Down and Let Stand Overnight to Dry Packing. Column Restarted and Packing Wet by Pouring Liquid in from Tbp
14 15
No. of Time Theoretical Plates in between Rate of --n-Heptane-Still Column H. E. T. P. Tests Boiling- Distillate Hours C'c./hr.a Mole per cent In. Cm. Column Started with Packing Dry
14 15 16 17 18
4.1
The actual measured rate. Height equivalent to a theoretical plate. A t higher rates the column flooded.
a
957
9 2 7 3 5
960 900 860 1080 1260
Actual measured rate.
99.9 98.8 98.8 95.4 89.0
8.8 6.9 3.8 2.2 0.8
...
103 113 101 102
...
1.1 1.0
1.1 1.1
...
2.7 2.5 2.8 2.8
INDUSTRIAL AND ENGINEERING CHEMISTRY
958
TABLE111. PRESSURE DROPFOR 3 / s 2 - I x ~ SINGLE ~ HELIXES IN -4 COLUMN WITH 0.79 INCH INSIDEDIAMETER AND 111 INCHES OF PACKED SECTIOK Rate of Boiling" Piessure Drop Rate of Roilinga Pressure Drop C'c./hr. Mm. H g . Cc 1hr Mm. H g 11 580 900 18 14 1000 624 22 780 1120b 21 28 810 19 a Actual measured rate for n-heptane-methylcyclohexane mixtures a t total reflux. b This rate is approaching flooding. ~
.
for one minute. This is a minimum value, since the takeoff tube did not catch all the condensate and some condensation took place below this tube. The results (Tables I to 111) are given in some detail so that the effect of preliminary wetting and other variables may be observed. T o ensure constancy of operation, certain of the tests were conducted for as long as 36 hours. The wetting of the packing by flooding was accomplished by raising the still heat so that the rate of distillation was too great for the capacity of the column. As soon as the flood had subsided, by momentarily shutting off the still heat, the latter was set for the desired rate of distillation. The data in the tables represent consecutive time intervals of continuous operation except where otherwise noted.
VOL. 29, NO. 8
These results show high efficiency combined with reasonable throughput and low-pressure drop per theoretical plate (approximately 0.3 mm. of mercury). The maximum measured rate of condensation in the 23.5-inch column was 1350 cc. per hour, and in the 111-inch column, 1260 cc. with n-heptanemethylcyclohexane mixtures. These figures correspond to 0.86 and 0.80 feet per second vapor velocity, respectively. The actual condensation rate is estimated to be 8 to 23 per cent greater. With this packing, columns of the order of 100 theoretical plates can be built in a laboratory of average height. Such columns have the advantages of simple packed columns, including cheapness, ease of operation, simplicity of operation, ruggedness, and low pressure drop per theoretical plate.
Literature Cited Beatty, H. 8., and Calingaert, G., IND. ENG. CHEM.,26, 504 (1934). Fenske, M. R., U. S. Patent 2,037,317 (April 14, 1936). Fenske, M. R., Quiggle, D., and Tongberg, C. O., IND.EXQ. CHEM., 24, 408 (1932). Fenske, M. R., Tongberg, C. O . , Quiggle, D., and Cryder, D. S., Ibid., 28, 644 (1936). Nickels, J. E., thesis, Pa. State Coll., 1936. Tongberg, C. O., Quiggle, D., and Fenske, M. R., IND. ENG. CHEM.,26, 1213 (1934). RDCEIVDDMay 28, 1937.
Isooctane Production by Simultaneous Polymerization and Hydrogenation V. N. IPATIEFF AND V. I. KOMAREWSKY Universal Oil Products Company, Riverside, Ill.
R
ECENTLY a new simultaneous reaction, hydropolymerieation, of olefinic hydrocarbons was described ( 3 ) . This reaction takes place in the presence of mixed catalysts consisting of a combination of polymerizing and hydrogenating agents. In the presence of such mixed catalysts and hydrogen the simultaneous polymerization and hydrogenation of olefinic hydrocarbons take place, resulting in the formation of hydrogenated polymers; this reaction was therefore called "hydropolymerization." I n the study of different catalysts adaptable for this reaction particular attention was given to phosphoric acid, because of its successful use in the polymerization of olefins (2) and the development of the industrial process of catalytic polymerization of cracked gases ( I ) . The most interesting and important hydrocarbon submitted to hydropolymerization was isobutylene. By hydropolymerizing isobutylene in the presence of a solid phosphoric acid-nickel oxide-iron catalyst under hydrogen pressure, it was possible to obtain direct a mixture of isomeric octanes. The experiments were conducted in a steel rotating autoclave, 1 liter in capacity. The catalyst and the liquid isobutylene were weighed in a steel liner which was afterwards placed in the autoclave. I n each experiment 80 kg. per sq. cm. of hydrogen were used. The liquid products of the experiment were fractionated through a Podbielniak column. The gases were analyzed by a combined Gockel and Podbielniak method. Isobutylene was obtained by catalytic dehydration of isobutyl alcohol over an alumina catalyst a t 350" C. The catalyst was prepared by mixing 1.5 parts of solid phosphoric acid
catalyst (1) with 1 part of reduced iron and 0.5 part of nickeloxide. Twenty grams of this mixed catalyst were used in each experiment. The foPowing table represents the results of two experiments: Temperature C. Reaction tirnk. hours Isobutylene taken grams Liquid product odtained, grama Isobutylene conversion, % Pressure drop during expt., kg./sq. om.
Expt. 1 250 12 108.7 100.0 92 36
Expt. 2 300 6 117.0 112.5 96 35
The results of the investigation of the product of each experiment are as follows: Expt. 1 10
Unsatd content of product yo" Octane'fraction (b. p., 1OO-i25O C , ) , yo of total liquid product Octane No. of octane fraction Gases from the reaction, %: Hydrogen Butane
Expt. 2 9
46 83 b
56 84
95.8 4.2
96 5.0
5 Determined by sulfuric acid method. b The fraction of this product boiling at IOO-llOo C . had an octane number of 100. The comparatively low octane number (83) of the total octane cut is probably due to the formation of isomeric octanes other than 2,2,4-trimethylpentane.
Literature Cited
,
(1) Ipatisff, U. S. Patents 1,993,512, 1,993,513, 2,018,065, 2,018,066, 2,020,649 (1935). (2) Ipatieff and collaborators, IND. ENG. CHEM.,27, 1067 (1935). (3) Ipatieff and Komarewsky, J. Am. Chem. Soc., 59, 720 (1937).
RECEIVED May 10, 1937. Presented under the title of "Hydropolymerization" before the Division of Organic Chemistry at the 92nd Meeting of the American Chemical Society, Pittsburgh, P a . , September 7 to 11, 1937.
