US2374870A - Vacuum distillation apparatus - Google Patents

Description

Patented May 11, 1945 VACUUM DISTILLA'HON APPARATUS Charles v. Litton, Redwood City, Calif.,- assignor of one-fourth to Jesse L. Markel and onefourth to Alexander M. Poniatoff, both of San Francisco, Calif.

Original application July 31, 1939, Serial No.

287,525. Divided and this application September 15, 1941, Serial No. 410,855

2 Claims.

This invention relates generally to high vacuum distillation apparatus such as is useful for the fractional distillation of a wide variety of materials. By high vacuum, I have reference to vacuums of the order of -5 mm. of mercury or higher.

It is an object of the invention to provide an apparatus of the above character which will be relatively simple in construction and operation, and which will make possible the separation of fractions having a high degreeof purity.

Another object of the invention is to make possible progressive fractionation and reflux action in connection with distillation at high vacuums.

Additional objects of the invention will appear from the following description in which the preferred embodiment of the invention has been set surrounding the passage forth in detail in conjunction with the accom- Fig. 2 is a side elevational view, in cross-section,

showing another embodiment of the invention.

Fig. 3 is a side elevational view, illustrating a plurality of units constructed somewhat as' illustrated in Fig. l, and connected together to form a continuously operating series.

Referring first to Figure 1 of the drawing, I have illustrated apparatus comprising the fractionating column "I, having a connection II to a vacuum pump or other form of evacuating equipment capable of maintaining a high vacuum. Communicating withthe lower end of the fractionating column there is a vessel l2 adapted to. contain a charge of material l3, and which under normal conditions receives 'heat from a suitable source during the distillation cycle. An

inlet pipe M is, indicated for introducing material into the vessel I 2.

The fractionating column I includes the series of fractionating cups I6. These cups can be in the form of rings as illustrated, and they are formed so that when filled with a condensed fraction, the fraction can overflow the inner lip into the next lower cup. The uppermost fractionating cup I6 is shown provided with a pipe connection l1, whereby the lightest ii-action collected in this cup can be withdrawn.

-sel l2.

The throat or passage l8 which connects the vessel I 2 with the interior of the fractionating column 10, is preferably provided with meansto prevent a washing up of any of the mother liquor I into the fractionating column. This means is preferably in the formof a downturnedlip l9,

I8. The space surrounding the region of lip l9 can form an additional fractionating cup 2|, as illustrated. A tube 22 can be provided to draw off the liquid accumulating in cup 2|, which in a typical instance represents material from which light ends have been removed, and which does not contain waxes, color components, and miscellaneous contaminants that "are caused to remain in the ves- Above the throat l8 the fractionating column I0 is provided with a substantially unobstructed passage 23, for free movement of molecules of the vaporized material leaving the charge of material undergoing treatment.

Use of the apparatus described above can be described as follows: A charge of the material undergoing treatment, which can be termed a mother liquid, is introduced into the vessel l2. The vacuum pump connected with tube II is placed in operatiomwhereby the interior of the apparatus is subjected to a high vacuum of the order of say 105 mm. of mercury. The charge I3 is maintained at a suitable temperature consistent with the character of the fraction or fractions to be removed'by applying heat to the same. Assuming maintenance of proper vacuum and temperature conditions, and also assuming that the exterior of the fractionating' column I0 is suitably heat insulated, as by means of heat insulating .materialor an evacuated space, various fractions are vaporized from the charge It The vacuum is such that the mean free path of movement of the molecules is at least as great as the distance between the lower fractioning.

cups and the surface of the mother liquid. Because of the slightly different temperature and pressure conditions existing at the various levels fractionating cup. This progressive fractionating and reflux action makes for utmost purity of the separated fractions, particularly with respect to. the lightest fraction removed from the uppermost fractionating cup.

The lip I9 serves the useful purpose of preventing contamination of the condensed fractions with mother liquid. Without this lip there is a tendency for the mother liquid to be washed upwardly to intermingle with the collected fractions. However, with this lip such mother liquid is returned back to the charge l3.

. ing an evacuated heat insulating jacket about the fractionating column. Thus in this instance I the walls of the column are surrounded by a sealed jacket which is in direct communication with the upper end of the column. Pipe ll connects to the jacket and the lightest fraction can be withdrawn from pipe l'la, instead of from the top cup of the column. Also liquid can be withdrawn from the cup 2| through pipe 22a,

. as for example where one desires a liquid from which the light ends have been removed, and which does not contain waxes, color components and miscellaneous contaminants remaining in i2.

Figure 2 represents a plurality of units similar to that'shown in Figure 1, connected in series.

.Pipe 26 in this instance represents introduction of the material undergoing treatment into an intermediate one of the fractionating rings of the first unit A. The lower vessel l2 of the unit A is shown connected to the drain pipe 27, which in turn leads to an intermediate one of the fractionating cups of the sec and 29 are shown for r the light fractions from the uppermost of'wiits A and B. Material from. the lower end of unit B can be drained through the pipe 39.

d unit B. Pipes '28 the overflow liquid passes into the next lower tinual or continuous removal of a lightfraction through Pipe 28. The same is also true of the material in the vessel I: of unit B, assuming of course that the volume of material in this receiver is maintained constant by continual drainage through pipe 30. v

With'reference to Figure 2, one of the units illustrated can be operated continuously in place of batch operation as described for Figures 1 and 3. For such operation it is desirable to introduce the liquid into an intermediate fractionating cup as indicated by lines 26 or 21 and to continually drain liquid from the lower vessel H to maintain a substantially constant liquid level.

The apparatus described above is capable of producing fractions of extreme purity. It can be used in connection with the distillation treatment or refining of a wide variety of products, including various mineral oils or petroleum products, and vegetable or animal oils. It can also be used to advantage to remove fractions such as vitamins or vitamin-like substances, from materials such as vegetable or animal oils.

I claim: 1. In high vacuum molecular distillation apparatus of the character described, a vertically disposed fractionatin'g column of the reflux type, said column including a plurality of vertically spaced collecting cups arranged whereby a con- 30' densed fraction in one cup may reflux into the cup below the same, said cups surrounding a substantially unobstructed column like vertical path for free-movement of vaporized molecules, means for introducing molecules of the vaporized material into the fractionating column, a jacket surrounding the column and having its upper end communicating with the upper end of said space above the uppermost cup of the column, and means for subjecting the fractionating column and said jacket to a high vacuum, the lower portion of said jacket serving to collect a fraction from a region above the uppermost cup of the column.

2. In high vacuum molecular distillation apparatus, a chamber serving to retain mother liquor undergoing distillation, a vertically disposed fractionating column comprising a plurality of vertically spaced cups arranged one above the other and each arranged for refluxing-collected In operating the apparatus of Figure 2, the I material undergoing treatment can be continuously bled into unit A through pipe 26, and

material can be continuously drained from vessel l2 of unit A, into the unit B, through pipe 21. The material in the lower vessel H of unit B can be mantained at a slightly" higher tempera- 'ture than the temperature of material in the.

vessel I 2 of unit A. It will be apparent that with such continuous operation the collected material in the receiver I2 of unit A will maintain constant characteristics, thus making possible conmaterial into the next lower cup, said cups being formed to surround and freely communicate with a substantially unobstructed column like space of substantial cross sectional area extending upwardly from the surface of liquid undergoing 7 treatment, means for subjecting the interior of the fractionating column to a relatively high vacuum, and a depending lip surrounding said space at a level intermediate the lowermost fractionating cup and the surface ofv the liquid, to prevent entrainment of mother liquor in the lowermost.

fractionating cup.

\ CHARLES V. LITTON.

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