US2396374A - High vacuum distillation apparatus - Google Patents

Description

March 12, 1946. K. c p. HICKMAN 2,396,374

HIGH VACUUM DISTILLATION APPARATUS Filed m. s, 1944 FIG. 1

DIST/LLAND UND/ST/LLED RES/DU our DRAW-0FF I HEATING FLUID IN HEATING FLU/D OUT DISTILLAND IN V KENNETH C.D.HICKMAN INVENTOR (IND/STILL ED REJ/DUE our mm D/J T/LLA TES B Y A TTORNE YS Patented Mar. 12, rate asses-i4 more vacuum/i nrsmmrron APPARATUS Kenneth ill. D. Hickman, Rochester, N. Y., as-

signor to Distillation Products, Inc., Rochester, N. Y a corporations! Delaware Application August 3, 1944, Serial No. 547,891

6 QJlalms. (Cl. 202-205) This invention relates to improved high vacuum distillation apparatus, and particularly to such apparatus wherein the vaporizing surface rotates and causes the distilland to flow thereover in a thin film by centrifugal force.

In all high vacuum, unobstructed path distillation apparatus heretofore used, thedistilland was necessarily heated by conduction through a metal support for the film of distilland. The distilland was, therefore, initially heated from the under side of the film and distillation could not take place until this heat had passed through the film to its upper or free surface. In prior art apparatus of this type, the vaporizing and condensing surfaces were positioned opposite each other and since the vaporizing surface was at high temperature and the condensing surface at low temperature, considerable heat loss took place. The destruction that a 'labile substance undergoes in such a still is a composite of the elements of destruction which occurs in each successive layer of distilland from the hot support to the outside evaporating surface, Since this surface is facing a cold condenser, there must be a very high thermal gradient through the oil and vention, but it is to be understood that these are given byway of illu tration and not in limitation thereof.

In the accompanying drawing wherein like numbers refer to like parts, I have illustrated two preferred forms of my invention wherein like numbers refer to like parts and wherein:

Fig. 1 is a vertical section of centrifugal still having a spiral-shaped vaporizing surface which is electrically heated and which is positioned between two rotatable condensing surfaces.

Fig. 2 is a vertical section of a modification of C the apparatus illustrated in Fig. 1, being provided destruction in the back layers may be abnormally high. a

This invention has for its object to provide highvacuum, unobstructed path distillation apparatus'whereby the foregoing difliculties are largely avoided. Another object is to provide high vacuum, unobstructed path distillation apparatus wherein the distilland film is, to a large extent, heated by application of heatto the distilling or free surface of the film. A further object is to provide high vacuum, unobstructed path distillation apparatus wherein the heat loss between the vaporizing and condensing surfaces is substanwhich distilland is caused to flow in a thin film.

by centrifugal force and condensing surfaces positioned on each side of the spiral vaporizing surface whereby vapors can readily pass to the condensing surface but heat is radiated from one convolution of the spiral to the other instead of being lost by radiation to the condensing surface as heretofore.

with a vaporizing surface having a double wall and with stationary perforated condensing surfaces, and

Fig. 3 is a fragmentary enlargement of the upper portion of the shaft bearing illustrated in Fig. 1. i I

Referring to Fig. 1, numeral I 0 designates a cylindrical still casing provided with an integral base I3 and a removable cover M which forms a gas-tight point with casing in at flange I6. Numeral l8 designates a hollow shaft which is closed at its lower end asindicated by dotted line 20 and which is housed in a rotatable manner in ' bearings 22 and 24.

Numeral 26 designates a spiral-shaped, vaporizing surface the. inner portion of which is rigidly mounted upon shaft 18 and which is rigidl maintained in the' position illustrated by supporting spiders 28 which are constructed of suitable insulating material, Spiral 26 is preferably of thin gauge metal so that it can be heated by its electrical resistance without undue waste of electricity. Spiral 26, is provided with inwardly turnededges 30 and withan inwardly turned end portion 32. The end of the spiral is also provided with a conduit 34 which protrudes into stationary gutter 36 which is connected to withdrawal conduit 38. p Y

Referring especially to Fig. 3', numeral 40 designates a metal ring or commutator mounted upon In the following description I have set forth several of the preferred embodiments of my inshaft l8 but insulated therefrom by insulating material 42. Numeral designates a bolt which is similarly insulated from shaft "land which is connected to electrical conductor 46 or commutator 40. Numeral 48 designates a brush makin electrical contact with insulated commutator 40 and which is connected toa suitable source of electric current by conductor 50. Conductor 46 passes through a suitable insulating and gas-tight bushing 41 in the lower part of the wall of conduit l8 and is then connected to the outer end ofspiral 26 in the manner illustrated. Numeral onto the inner portion of spiral vaporizing surface 26.

I Numerals 62 and 64 designate circular condens ing surfaces which are mounted upon shaft I8 and which rotate therewith. Numerals 66 and 6B designate circular gutters into which the periph- V cries of condensing surfaces 62 and 64 respectively protrude; Gutters 68 and 68 are connected 6 to a withdrawal conduit 18 which is in turn connected to-a' cooler 12 and a conduit M through which distillate is withdrawn. Cooler 12 is connected to the intake side of circulating pump 16, the exhaust side of which is connected to filter l8. Numeral 80 designates a conduit for circulating cool, filtered distillate back onto the upper surfaces of condensing surfaces 62 and 5d. Numeral 82 designates evacuating conduits connected to vacuum pumps (not shown).

1 Hot heating fluid is introduced through conduit,

Referring to Fig. 2 it will be noted that spiralshaped, vaporizing surface 2'! which is analogous to element 26 of Fig. 1 is double walled to permit heating by circulation of a heating fluid through the space between the double walls. Numerals 90, 92, and 9d designate annular channels in nected conduits 96, 98, and Hill. Numeral I02 designates a conduit connected at its upper end to an opening in shaft id at a point opposite channel 90 and which is connected at its lower extremity to the space between the double walls of vaporizing surface 21. Numeral E04 designates a conduit which similarly communicates at its upper extremity to channel 92 and which passes through the lower portion of the hollow shaft i8 and is connected at its lower extremity to the outer periphery. of the space between the double walls of the spiral vaporizing surface. Numeral I06 designates a"c9nduit communicating with channel packed gland 24 to which are respectively co'nand is thrown into gutter 36. This residue is then withdrawn from the still through conduit 38.

Condensate from condensing surfaces 62 and 64 is thrown into gutters 8'6 and 68 and flows thence into conduit Ill. This condensate is partially bled oir' through conduit I4 and the re- 7 mainder is cooled in cooler 12, is forced through filter 18 by pump I6 to remove material insoluble at the lower temperature, such as sterols. The

.cool, filtered condensate is then introduced by conduit 80 into the central recessed portion of condensing surfaces 62 and 84 and is then thrown by centrifugal force to the periphery thereof. This cool condensate serves to cool the condens- -ing surfaces to a satisfactory, low, condensing temperature.

In operating the apparatus illustrated in Fig. 2, the system is evacuated as described above in connection with Fig. l and the spiral vaporizing urface 21 is rotated by force applied to shaft it.

96' into channel 90 from which it flows through conduit I02 into the space between the double walls of spiral 2'l. Spent heating fluid passes into conduit ill thence into channel 92 and flows from the still through'conduit 98. Distilland is introduced through conduit it into channel '96 from which it flows through conduit H06 onto the inside part of spiral 2! by way of openings 59. Undistilled residue is caught in gutter 86 and is removed through conduit 38 as previously described. Condensate is condensed on condensers lot and III) which are cooled by conduits int and ill respectively. The condensate flows into gutters ll2and H4 respectively and removed from the still by conduits H6 and H8 respectively. It will these separate portions and can be separately re- 94 and with the inner inside surface'of the spiral vaporizing surface by way of openings 60.

Numerals I08 and H0 designate condensers I constructed in the form of a plurality of nested truncated cones which are spaced to permit the passage of non-condensable gases as described in Hickman and Hecker Patent 2,180,052, November 14, 1939. These condensers are provided respec- ,tively with gutters H2 and I, at their lower portions into which'condensabe drains and is and opening 60 onto the inside ofspiral-shaped,

vaporizing surface 26. This distilland then flows by centrifugal force in a thin film over the inside surface-"ot-spiral 26. During this-passage over 26, the distilland is' heated to distillation temperature. Vapors are generated and pass sideways to condensing surfaces 62 and. Undistilled residue is prevented from being thrown by centrifu= gal force from the spiral 26 by end plate 32, and

- Thus, the heating fluid may be a combined heating.

the distilland is very efllcient.

moved in the individual removal conduits as illustrated. While itmakes little difference in which d'rection the spiral is rotated, it is preferred that the equipment as illustrated be retated in a clockwise direction.

It is to be understood that many modifications can be made in the equipment illustrated without departing from the spirit or-scope of my invention. Thus, the spiral convolutions may be widely or closely spaced. It,is preferred for high vacuum, unobstructed path distillation that'the convolutions be widely spaced. Also, the spiral may be a single lead spiral or multi-lead. The number of convolutions can, of course, be increased or decreased. The manner of circulating heating fluid shown in- Fig. 2 can be modifled'considerably.

and heat exchange fluid as described in my copending patent application Serial No. 541,253, filed June 20, 1944. Other modifications will be obvious to those skilled in the art.

The invention has the outstanding advantage that heat loss between the vaporizing and condensing surfaces of a high-vacuum, unobstructed path still is greatly reduced. Another important advantage is that the distilland is not only heated by the supporting metal surface. as heretofore.

but is also heated by radiation from the inner convolutions so that the application of heat to Also, by partly obstructing the: exit off vapor by placing a hot object near, although wev raise the temperature ot the surface by an amount necessary to comthe residue, therefore. flows through conduit 34 pensate for the molecules. returned, we may so lower the thermal gradient that the fall in temperature and thus decomposition in the back layers of oil more than compensates for the rise of the front layers. The long spiral also gives the opportunity of much renewal'of the distilling surface of turbulence.

-What I claim is:

l. High-vacuum, unobstructed path distillation apparatus adapted to cause distilland to flow in a thin film by centrifugal force over a heated vaporizing surface, said apparatus comprising in combination a spiral-shaped, rotatable, vaporizing surface positioned between two condensing surfaces, and within a closed casing, means for maintaining a, vacuum between the spiral-shaped, vaporizing surface and the condensing surfaces. means for introducing distilland onto the surface of the spiral vaporizing surface at a point near its center, means for removing undistilled residue from the outer portion of the spiral vaporizing surface, means for heating the spiral vaporizing surface, means for cooling the condensing surfaces, and means for removing the condensate from said condensing surfaces.

2. High-vacuum, unobstructed path distillation apparatus adapted to cause distilland to flow in a thin film by centrifugal force over a heated vaporizing surface, said apparatus comprising in combination a spiral-shaped. rotatable, vaporizing surface having a wide space between the convolutions of the spiral, which spiral is positioned between two condensing surfaces, and within a closed casing, means for maintaining a vacuum between the spiral-shaped vaporizing surface and the condensing surfaces, means for introducing distilland onto the surface of the spiral vaporizing surface at a point near its center, means for removing undistilled residue from the outer portion of the spiral vaporizing surface, means for heating the spiral vaporizing surface, means for cooling the condensing surfaces, and means for removing the condensate from said condensing surface.

4. High-vacuum, unobstructed path distillation apparatus adapted to cause distilland to flow in within a closed casing, means for maintaining a vacuum between the spiral-shaped vaporizing surface and the condensing surfaces, means for introducing distilland onto the surface of the spiral vaporizing surface at a point near its center, means for removing undistilled residue from the outer portion of the spiral vaporizing surface,

means for circulating heating fluid between the vaporizing surface, said apparatus comprising in combination a spiral-shaped, rotatable, vaporizing surface, having a wide space between the convolutions of the spiral which is positioned between two perforated condensing surfaces, and within a closed casing, means for'maintaining a vacuum between'the spiral-shaped, vaporizing surface and the perforated condensing surfaces, means for introducing distilland onto the surface of the spiral vaporizing surface at a point near its center, means for removing undistilled residue from the outer portion of the spiral vaporizing surface, means for heating the spiral vaporizing surface, means for cooling the condensing surfaces, and

means, for removing the condensate from said condensing surfaces.

6. High-vacuum, unobstructed path distillation apparatus adapted to cause distilland to flow in volutions of the spiral, which spiral is positioned between two rotatable condensing surfaces, and

within a closed casing, means for maintaining a vacuum between the spiral-shaped vaporizing spiral vaporizing surface, means for returning cooled condensate to the condensing surfaces, and means for removing the condensate from said condensing surfaces.

a thin film by centrifugal force over a heated, vaporizing surface, said apparatus comprising in combination a plurality of spiral-shaped rotating vaporizing surfaces havinga wide space between the convolutions of each spiral which are mounted upon a single rotatable shaft, and each of which is positioned between two condensing surfaces, and within a closed casing, means for-maintain: ing the vacuum between the spiral-shaped, vaporizing' surfaces and the condensing surfaces, means for introducing distilland onto each of the spiral surfaces near the center thereof, means for removing undistilled residue from the outer portion of the spiral surfaces, means for heating the spiral surfaces, means'for cooling the'condensing surfaces, and means for removing condensate from said condensing surfaces.

' KENNETH C. D. HICKMAN.

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