US3020211A

US3020211A - Film-forming and wiping distillation process and apparatus for carrying out the same

Info

Publication number: US3020211A
Application number: US776789A
Authority: US
Inventors: Arthur F Smith
Original assignee: Individual
Current assignee: Individual
Priority date: 1958-11-28
Filing date: 1958-11-28
Publication date: 1962-02-06
Anticipated expiration: 1979-02-06

Description

A. F. SMITH 3,020,211 FILM-FORMING AND WIPING DISTILLATION PROCESS Feb. 6, 1962 AND APPARATUS FOR CARRYING OUT THE SAME 2 Sheets-Sheet 1 Filed NOV. 28, 1958 36 MII!! 62 .IIL

ARTHUR F. SMITH FJ INVENTOR.

6 5 R R R O N E LE R mm mw N m mm MMMI'MAKbI'NLI'TEIVDInE AP EA AD VM HJ X O PW E c c O l 2 M 5 nIU. I.

ATTORNEY Feb. 6, 1962 A. F. SMITH 3,020,211

FILM-FORMING AND WIPING DISTILLATION PROCESS AND APPARATUS RoR CARRYING OUT THE SAME Filed Nov. 28, 1958 2 Sheets-Sheet 2 l 9A` ll INVENTOR. ARTHUR F. SMITH ATTORNEY ttes 3,020,211 FILM-FRMING AND WIPING DISTILLATIN FRDCESS AND APPARATUS FR CARRYING GUT THE SAME Arthur F. Smith, 1516 Lake Road, Webster, N51. Filed Nov. 28, 1953, Ser. No. 776,739 14 Claims. (Cl. 2132-64) Serial No. 571,626, tiled March l5, 1956 and now U.S.

Patent No. 2, 955,990, granted October 1l, 1960i.

For eicient fractional distillation, it is customary to maintain counter-current contact between distilland, that it, the liquid that is being distilled, and the vapor that is formed during distillation. Frequently, this is accoi plished in a tower in which vapors are passed upwardly through packing or bubble caps, while liquid is passed downwardly, and intimate contact is effected between the vapor and liquid at successive levels in the tower.

These expedients are not available, or are not satisfactory, for distillations at reduced pressure, and particularly for distillation under high vacuum, because the packing or bubble caps ofrer resistance to the passage of vapor. Moreover, expedients of this type require that the liquid be maintained at distilling temperature for a relatively long period of time, and thus subject the liquid to increased thermal hazard.

It has been proposed in the past, for example in the United States patent of DYarmett, 2,040,837 and 2,040,- 838, and of Perry et al., 2,539,699, to employ distillation apparatus in which a rotary brushY is mounted coaxially within a cylindrical shell so that the bristles of the brush engage the shell wall at least initially. The brush is mounted on a hollow, cooled shaft. Vapor is passed upwardly through the shell and is condensed on the bristles of the rotating brush, and is returned under centrifugal force to the shell wall, for reheating, and revaporization. Stills of this type effect reasonably good fractionation, but have the mechanical disadvantage that if both brush and shell are made of metal, the brush galls on the metal shell and both wear rapidly. Moreover, if the shell is not formed with a perfectly cylindrical evaporating surface, the engagement of the bristles against the evaporating surface is not uniform; and after some bristle wear, parts of the evaporating surface may not be engaged at all, so that hot spots develop which produce burning and charring. When a metal brush is employed in conjunction with a glass shell, the thermal efficiency of the still is quite low, because of the poor conductivity of the glass.

One object of the present invention is to provide fractional distillation apparatus of relatively simple construction, that has high thermal etliciency, that offers an extremely low thermal hazard, and that is free from hot spots, burning, and charring.

A related object of the invention is to provide frac tional distillation apparatus of the falling lm type, in which the liquid in the tilm is continuously redistributed over dterent portions of the evaporating surface, to maintain a high degree of turbulence and high thermal conductivity.

Another object of the invention is to provide a practical fractionating still for high vacuum distillation, that provides a large number of theoretical plates in a minimum volume.

ECC

Another object of the invention s to provide fractional distillation apparatus that effects intimate and thorough contact betwen vapors and liquid, even at high vacuum, with a minimum space requirement, and with an extremely low throughput time.

A further object of the invention is to provide a more etiicient fractionating process for separating liquids into fractions, and particularly, a process that is useful for the fractionation of viscous liquids of low thermal conductivity.

In the drawings:

FIG. l is a section of a fractionating still, the fractionatng portion of the still being shown by a section taken on the line 1 1 of FIG. 2, looking in the direction of the arrows, the remainder being an axial section, the still being particularly adapted for use at reduced pressures, and constructed according to one embodiment of this invention;

FIG. 2 is a section taken on the line 2-2 of FIG. l, looking in the direction of the arrows;

FIG. 2a is a fragmentary section similar to FIG. 2, but showing a modied construction according to another embodiment of the invention;

FIG. 3 is a fragmentary section taken on the line 3-3 of FIG. 2, looking in the direction of the arrows;

FIG. 4 is aV section similar to the Section of FIG. 2, but showing a fractionating partial condenser structure that is constructed according to another embodiment of the invention;

FIG. 5 is a schematic diagram illustrating the closed thermal circuit that'preferably is employed in conjunction with stills constructed according to this invention;

FIG. 6 is an axial section taken on the line 6-6 of FIG. 7, looking in the direction of the arrows, of a fractionating still that is. particularly adapted for operation at high vacuum, constructed according to another ernbodirnent of the invention;

FIG. 7 is a section taken substantially on the line 7--7 of FIG. 4, looking in the direction of the arrows; and

FIG. 8 is a view in elevation, taken on the line 8 8 of FIG. 7, looking in the direction of the arrows.

Referring now in detail to the drawings by numerals of reference, and particularly to FIGS. 1, 2, and 3, 10 denotes a casing that is adapted to be supported in an upright position and that has a bottom bulb portion 11 of generally spherical contour. A nipple .12 is secured to the bulb portion 11 at its lowest point, to permit drainage of liquid from the bulb. A valve or stop cock 14 is connected to the nipple 12, to permit this line to be closed off in vacuum tight fashion.

The casing 1t) has a cylindrical portion 15 that is integral with the bulb 11-1 and whose axis is aligned with the center of the bulb. An inlet tube or arm 16 is secured to the cylindrical portion 15 approximately midway between its ends. The tube 1-6 is generally upwardly directed, and a funnel member 17 is secured, in vacuum tight fashion, to the upper end of the tube 16. The lower end of the funnel member 17 is formed with a reduced portion 2t) that projects into the tube 16, in radially spaced relation to the wall of the tube. The funnel member 17 preferably is formed at its upper end with an internal ground female surface 21, in which a male member can be inserted in vacuum tight fashion.

The casing 10 is enlarged at the upper end of the cylinder 15, and is ilared outwardly, and downwardly, and is then continued upwardly again, to provide a head 26 that is of enlarged diameter relative to the cylinder 15, and that drains into a gutter or alembic 22. A generally downwardly directed tube 24 is connected to` the gutter 22, to permit liquid that accumulates in the gutter to be drained. The tube Z4 is formed at its outer end with a 3 ground male surface 25, for vacuum tight connection to a receiver (not shown).

The head 26 is formed at its upper end with an outwardly thickened wall portion to provide a flat base 27 on which a cap Eil is mounted. The cap 36 is formed with a ring-shaped channel in its lower face, and an -ring 31 is seated in the channel and is compressed between the cap 30 and the surface 27, to provide a vacuum tight seal.

A coil 2S is mounted in the head 26, with its inlet and outlet lines passed `through the wall of the head 26 in vacuum-tight fashion. The coil convolutions are disposed closely adjacent the inner surface of the wall of the head 26, to permit condensate to drain into the gutter 22. A nipple 29, of relatively large diameter, is secured to the wall of the head 26 adjacent its upper end. The nipple 29 is formed at its outer end with a ground male surface 32, for vacuum-tight connection to a vacuum pump or other evacuating means.

A bearing is mounted centrally in the cap 30, and a hollow shaft 36 is rotatably journaled in the bearing 35, in vacuum tight fashion. The shaft 36 projects into the casing 10 substantially coaxially with the head 26 and the cylinder 15. A plug 37 is mounted in the bore of the shaft 36 at its -lower end, to close the lower end of the shaft. lA short shaft 4G is secured to the lower face of the plug 37 to project downwardly, coaxially with the shaft 36, and an irnpeller 41 is secured to the lower end of the shaft 40.

A partial or fractionating condenser 42 is mounted on the shaft 36, to rotate upon rotation of the shaft, within the cylindrical portion 15 of the casing 16. The axial length of the condenser 42 corresponds roughly to the axial length of the cylindrical portion 15, and the upper end of Ithe condenser terminates at a level below the gutter 22. The condenser 42 comprises three plates 44 that are equiangularly spaced about the shaft 36. Each of these plates is curved in horizontal section, and its center portion is engaged in an axially-extending groove in the shaft 56, yas shown in FIG. 2. The plates 44 can be secured to the shaft 36 by spot welding, bolts, or other convenient means (not shown). In making the assembly comprising the three plates 44 and the shaft 36, the plates 44 preferably are irst curved to the desired shape, then are pressed with the shaft 36 on a mandrel to be sure that the grooves that are formed in the shaft 36 and the curved center portions of the plates 44 conform. Three axially extending plates 45 are secured between the confronting surfaces of adjacent plates 44, at equally radially inwardly spaced locations from their free ends, to form three generally U-shaped axially extending channels. plates 46, that are curved in substantially-the same manner as the plates 44, are secured to the plates 44, in spaced relation thereto, by end pieces 47 that are welded in vacuum-tight fashion, or otherwise secured, between the adjacent radial ends of the

plates

44, 46 respectively. Other strips 49 (FIG. l) are secured in vacuum-tight fashion across the space between the upper and lower adjacent ends of each pair of

plates

44, 46, respectively, to provide three closed chambers 48 between the three pairs of spaced

plates

44, 46 respectively. Each chamber 48 is bounded at its sides by one of the plates 44, two of the upright strips 47, the plate 46 that is secured to the two strips 47, and the upper and lower end closure strips 49. Apertures Si) are provided, at spaced upper and lower axial locations along the shaft 36, to provide communica.- tion between the bore of the shaft 36 and the three chambers 48, iat the axially upper and lower ends of the chambers. A pair of rings S1, 52, are secured to the upper and lower ends yof the

plates

44, 46 respectively, to rigidity these plates. The lower ring 52 provides a stop at the lower end of the three channels.

A plurality of wiper elements 54 `are mounted one above the other in each of the three channels. These wiper elements 54 are curved at their upper ends, as shown in FIG. 1, so that they can slide freely one `on the other,

Three other 1 for independent outward radial movement under centrifugal force as the shaft 36 and the condenser 42 are rotated. Each wiper elements 54 is formed with `a plurality of Slots 55 that are milled or molded in its face, to provide a plurality of lands 56 that engage the inner or evaporating surface of the cylindrical portion 15, upon rotation of the condenser. The slots 55 are formed with parallel Walls that are inclined to the horizontal, so that relative to a clockwise direction of rotation of the condenser 42 relative to FlG. 2, the slots are inclined downwardly from the leading edge of the wiper 54 to its trailing edge.

in the modified form of the invention shown in FIG. 2A, the cuter plates 46 yare curved at their lower ends, as denoted at 57, so that the axially-extending spacers 47 are eliminated.

o provide means for rotation of the shaft 36, a pulley wheel 6d is secured to the portion of the shaft 36 that projects upwardly through -the bearing 35.

To permit the circulation of heat exchange fluid to and from the condenser 42, a rotary coupling 61 is connected to the upper end ofthe shaft 36. The coupling 61 is of a standard make, such as, for example, the type described in US. Patent 2,407,745; and it includes a nipple 62 that is threaded, in Vacuum tight fashion, into the upper end of the shaft 36, for rotation upon rotation of the shaft. The nipple 62 is rotatably journaled in a housing 64. A tube 67 depends downwardly from the housing 64 coaxially within the bore of the shaft 36, and the bore of the tube 67 communicates with the fluid outlet 66 within the housing 64, in iiuid tight fashion. The annular space between the tube 67 and the shaft 36 communicates with the inlet 65, within the housing 64, in fluid tight fashion. A metal ring 70 is welded or otherwise secured between the lower end of the tube 67 and the inner surface of the shaft 36, to close the annular lspace to the iiow of heat exchange lluid below the upper set of apertures 50.

To heat the casing 10 during distillation, I prefer to employ .an electrical heating jacket 71 of standard type. However, I may also apply heat directly to the bulb 11 as well as, or instead of, to the wall of the cylinder 15.

While the casing 19 can be supported in substantially any convenient, desired manner, I prefer to support it by a modified pipe coupling 72, that engages the upper end of the head 26, around the outwardly iiared upper portion of the head. The coupling 72 can in turn be supported from a stand or in any other convenient manner. The coupling 72 is secured to the cap 30 by bolts 74.

To use this apparatus for a batch fractional distillation, a quantity of the liquid, that is to be distilled, is introduced into the casing 10 through the funnel member 17. The funnel member 17 is then closed in vacuum tight fashion. The liquid runs down the inner surface of the wall of the cylinder 15 into the bulb 11. A receiver is connected to the nipple 24 that drains the gutter 22, and the nipple 29 is connected to a vacuum pump. The pulley wheel 60 is driven to rotate the shaft 36, and the impeller 41 agitates the liquid in the bulb 11, throwing some of it up into the cylinder 1S, and constantly exposing fresh surfaces of the liquid so that degassing is facilitated as the casing is evacuated. Heat is applied to the casing through the heating jacket 71 and, initially, by a burner that is played directly on the lower surface of the bulb 11. Air is caused to circulate into the heat exchange uid inlet 65, through the annular space between the tube 67 and the shaft 36, through the upper set of apertures 50 and into the three condenser chambers 48, for downward passage through the condenser chambers to their lower ends, thence back through the apertures 50 at the lower ends of the chambers and into the bore of the shaft 36, -to travel upwardly into the bore of the tube 67, thence to be discharged through the outlet 66. Cooling fluid, such as, for example, cold water, is circulated through the condenser coils 28 in the head 26 of the casing.

Instead of circulating air through the chambers 48,

I can connect the coil 28 to discharge into the inlet 65, to circulate water through the chambers 48. In this way, both the condenser 42 and the coil 28 are water cooled, but the coil 28 is always the cooler of the two.

When distilling temperature is reached, vapors are given off by the liquid in the bulb 11, and pass upwardly into the cylinder 15. The vapors condense on the other surface of the cooled plates 46, and the condensate is caused to tlow, by centrifugal force, on the surface of the plates 46 radially outwardly until it ows from the condensing surfaces back onto lthe inner, evaporating surface of the cylinder l5.

The condensate that flows on to the evaporating surface flows downwardly over the evaporating surface in a film, under the influence of gravity, and as it flows downwardly, it is heated by heat from the heating jacket 7l, and also, by some heat transfer that occurs with the ascending vapor. As the liquid ows downwardly over the evaporating surface, the liquid is continuously removed from the evaporating surface by the wipers 54 that are thrown outwardly under the infiuence of centrifugal force as the shaft 36 is rotated, to engage the evaporating surface. The removed liquid passes into the slots 55, and is accelerated downwardly over the evaporating surface and then is discharged back onto the evaporating surface, again to flow downwardly over the evaporating surface in a iilm under the influence of gravity. The wiping action accelerates the ow of liquid over the evaporating surface, so that the liquid in film form is subjected to an extremely low thermal hazard. Moreover, the action of the wipers Se maintains the liquid in the fiim in a highly turbulent state, so that excellent heat transfer is obtained,

even though the liquid may be viscous and characterizedv by low thermal conductivity.

After repeated vaporization and condensation during its upward travel, some vapor passes from the cylinder into the head 26, and is condensed on the coils of the condenser 28. The condensate falls into the gutter 22, and can be collected in a receiver secured to the nipple 24. Distillation is continued until the desired fraction has been collected. To discontinue the distillation, the liquid should be cooled under vacuum, to prevent any charring that might occur upon exposure of the heated liquid to the atmosphere. If desired, several separate fractions can be collected. The performance of even a small column, having a diameter on the order of three to six inches for the cylindrical portion 15, is on the order of several theoretical plates, and sharply defined fractions can be collected easily.

To use the apparatus illustrated in FIG. 1 for con-Y tinuous distillation, the input liquid is supplied continuously, at a desired feed rate, through the funnel shaped member 17, from which it falls down over the evaporating surface of the cylinder f5. For continuous operation, the impeller 4l. need not be employed, and can be detached. The undistilled residue is withdrawn continuously through the nipple 12 and the opened valve 314. Sufficient heat is applied through the heating jacket 71 to evaporate or distill a fraction of the desired size, that condenses on the coil 28. As the liquid is fed into the cylinder 15, it is immediately subjected to the wiping action, that insures optimum heat transfer and minimum thermal hazard. For a continuous operation, best results are obtained by controlling still operation according to the size of the fraction that it is desired to separate.

Stills of this type are particularly desirable for the recovery of vitamin A from fish oils, and for the recovery of vitamin E from vitamin E concentrates, because unusually high concentrations can be obtained by single pass through the still, because of its fractionating ability. This still is also very valuable for the purification of drugs that have a high intrinsic value and low thermal stability, and which often are particularly difficult or impossible to fractionate and recover by other means. Small laboratory models of the still are valuable research tools for many purposes. For example, when the product recovery (total) condenser is not operated, and the fractionating condenser is operated at equilibrium, valuable equilibrium data can be obtained that is useful for many purposes.

rhose skilled in the art will readily recognize that many variations in the structure and arrangement of the still components are possible, within the scope of my invention. For example, as shown in FIG. 4, to simplify the still structure, I can mount the plates 44' on the shaft 36 as before, with wipers 54 mounted in generally U-shaped channels that are provided between the confronting, radially outer surfaces of the plates 44 and the axiallyextending plates 45. In this simplified embodiment of the invention, the heat exchange uid is circulated downwardly through the annular space between the shaft 36 and the tube 67', and is withdrawn through the bore o-f l `the tube 67'; and for optimum cooling characteristics, I prefer in this embodiment of the invention to extend the tube 67' concentrically downward within the shaft 36 almost to the bottom of the shaft. The plates 44 are coldest where they are secured to the cooled shaft 36', and become progressively warmer in a radially outward direction. While this structure is considerably simplified as compared with the structure shown in FIG. 2, the condensing action may be less complete.

Particularly for larger stills, l prefer to employ a closed thermal circuit in which a single heat exchange fluid is circulated and is caused to heat the distilland to effect Vaporizatio-n, and to effect, while at a cooler temperature, both partial condensation in the fractionating condenser and total or least substantially complete condensation in the final or upper condenser. For this purpose, it is desirable to employ a heating jacket on the still, thro-ugh which the .heat exchange fluid, in the hot phase of its cycle, can be circulated.

A preferred form of closed thermal circuit is illustrated schematically in FIG. 5. A heat exchange fluid, preferably a phase-changing fluid, is compressed in a vapor compressor, to transfer energy to it to make it hot. The hot heat exchange fluid is passed through a heating jacket to effect vaporization of the fluid in my fractionating column. As applied to FIG. 1, for example, the hot heat exchange fluid would be circulated in a jacket about the cylinder 15, to transfer heat to the liquid in the film on the evaporating surface, to cause it to vaporize. In this part of the cycle, the heat exchange fluid loses heat and becomes cooler. The cooled heat exchange fluid is recovered and passed through an expansion valve that reduces its pressure rapidly and that causes self-cooling. The coid fluid is then passed successively through the total condenser, then through the partial condenser. In these condensers, the fluid becomes increasingly warmer. The fluid is withdrawn from the partial condenser at an elevated temperature and is compressed in the vapor cornpressor, to heat it for another cycle. As applied to the apparatus in FIG. l, the cooled Huid would pass from the expansion valve through the coils of the total condenser 28, thence through the inlet to pass downwardly through the annular space between the tube 67 and the wall of the shaft 36, to be passed through the apertures 5t? into the condenser chambers 4S for downward passage in these chambers, thence to return through the lower set of apertures 5t) for passage upwardly through the bore of the tube 67, to be discharged through the outlet 66 and compressed in the vapor compressor.

The horizontal or transverse curvature of the condens ing surfaces can also be moditied, within the scope of the invention. Referring to FIG. 2, it can be seen that as the condenser is rotated, a portion of the condensate that forms on a given condensing surface, of one curved plate 46, is returned to the evaporating surface at the trailing edge of one column of wipers, and the balance, probably slightly more than half, of the condensate is returned to the evaporating surface at the leading edge of the following column of wipers. The condensate that is all returned to the evaporating surface at the leading edge of the column of wipers is immediately spread on the evaporating surface by this column of wipers, so that a high degree of turbulence is maintained and little or no splashing occurs at this point. At the trailing edge of the same column of wipers, the condensate that is returned to the evaporating surface is acted on substantially only by gravity, until it is struck by the following column of wipers. By modifying the transverse curved shape of the condensing surfaces somewhat, to provide a teardrop type of curvature, l can cause a larger percentage of the condensate to be returned to the evaporating surface at the leading edge of each column of wipers. in such a modification, the condensing surface would fall back sharply, that is, radially inwardly, at the trailing edge of each column of wipers, to reach a maximum depth at a location not far angularly spaced from the trailing edge of that column of wipers, and then would curve outwardly toward the leading edge of the following column of wipers, so that a major portion of each condensing surface would be sloped toward the leading edge of one of its associated columns of wipers.

I can use one or more columns of wipers. For mechanical reasons, I prefer to use two or more columns of wipers in an equiangularly-spaced arrangement, to distribute evenly the load on the bearings. For large stills, for example, six or eight columns of wipers may be employed.

Referring now to the modied embodiment of the invention shown in FGS. 6, 75 denotes a generally cupshaped base that is adapted to be supported on a plurality of legs 76. A bearing '77 is secured to project through the lower part of the base 75, and a shaft 73 is journalcd in this bearing 77. A pulley wheel '79 is mounted on the lower end of the shaft 78, to permit the shaft 7S to be rotated by a suitable drive belt and motor (not shown). A rotor gli, that is generally shaped like a flower pot, is secured to the upper end of the shaft for rotation within the base 75. A plurality of electrical heaters 81 are disposed in the space between the confronting surface of the rotor 30 and the base 75, A generally U-shaped gutter 82 is mounted adjacent the upper end of the rotor, and a splash ring 84 is seated in the gutter 32, and is formed with a generally radially inwardly projecting flange that extends over the upper edge of the rotor.

To supply heated feed liquid to the rotor Si?, a heat exchanger 85 is mounted adjacent the base 75, and feed liquid from a pump 86 is forced through coils S7, within the heat exchanger y8S, thence outwardly through a pipe S8 that is bent over upon itself, within the still, and that has a free lower end 90 that is bent laterally, to direct the feed liquid onto the lower surface of the rotor t), in the direction o-f rotation of the rotor.

The splash ring S4 is disposed to catch liquid residue as it leaves the rotor 80, and to direct it into the gutter 82. To remove the residue from the gutter 82, a line 91 is connected from the gutter S2 to a pump 92, that forces it through the heat exchanger 85, in which it transfers some of its heat to the input liquid in the coils 87.

A dome 94, that is generally shaped like an inverted cup, is mounted in vacuum tight fashion over the base 75. The dome is provided with an internal jacket 95 through which cooling fluid may be admitted thro-ugh a line 98, to cause condensation on the dome, and a ringr 96 is mounted in the dome, beneath the jacket 95, to recover the condensate.

A fractionating condenser 97 is suspended on struts 99 from the dome. This condenser is formed with a lower, generally horizontal disc 11G and an upper, generally horizontal disc 111. A plurality of curved metal members 112 are secured between these two discs to provide a plurality of generally vertically extending condensing surfaces 11d (FIGS. 7 and 8) that lare curved7 in horizontal section, so that they are concave relative to the evaporating surface, which is the inner, generally conical surface of the rotor St). A plurality of plates 116 are secured, respectively, between the confronting surface of the metal members 112, adjacent their radially outward, free ends, to provide six generally axially extending, U-shaped channels. A pipe 117 is secured at its upper end to the dome to communicate with the jacket remote from the cold water inlet 98, and is extended downwardly and, adjacent its lower end, is connected to a ring-shaped manifold pipe 12d. Six risers 122 (FIG. 6) are disposed in contact with the plates 116 and with the adjacent portions of the confronting surfaces of the members 112. The lower manifold ring 120 is connected to the lower ends of these risers 122 through restricted openings that provide uniform flow of cooling lluid into the risers. The risers 122 are connected at their upper ends to an upper manifold ring 124i, which in turn is connected to a discharge pipe 125. This pipe 125 is connected at its upper end to a central compartment 126 of the jacket 95, that is separated from the rest of the jacket by a baille 127. Water is discharged from the compartment 126 through a line 13h. Cooling water thus can be caused to circulate from the dome jacket 95 through a line 117 into the lower manifold ring 120, up the risers 122 into the upper manifold ring 124, through the line 125 into the compartment 126, thence out the discharge line 130, at the upper center part of the dome.

Columns of wipers 131 are mounted in the U-shaped channels of the condenser 97, and preferably are spring pressed outwardly by springs 132 in the channels, for engagement against the surface of the rotor 80 under the influence of gravity and under the spring pressure. Each column of wipers is supported at its lower end on the disc 110. Each wiper in each column is free to move outwardly, independently of the other wipers in the column, to engage the surface of the rotor 80'.

As shown in PPG. 8, the condensing surfaces 114 have a plurality of small gutters 134 welded or Otherwise secured to their faces, to receive condensate as it ows downwardly on the condensing surfaces, collect it, and return it, under the inlluence of gravity, to the evaporating surface of the rotor. These gutters 134 are inclined, to return the condensate to the evaporating surface immediately in advance of a column of wipers 131.

A large manifold 138 is connected in vacuum-tight fashion to the still, for connection to a diffusion pump for evacuation of the still.

To operate a still constructed according to this embodiment of the invention, the still is evacuated, and current is passed through the electrical heaters S1 to heat the rotor Si?. The rotor 80' is rotated, and feed is pumped into the still, by the pump 86, through the line 88, to the lower end of the rotor. Centrifugal force causes the liquid to spread rapidly over the rotor surface in a thin film, and to climb upwardly to be discharged from the upper end of the rotor onto the splash ring 84, for collection in the gutter S2. As the liquid travels over the inner surface of the rotor 80, it is heated, and at the same time, is repeatedly removed from the rotor surface by the wipers 131, and reapplied thereto, to produce a kturbulent film. In this embodiment of the invention, the inclination of the slots in the wiper elements can be moditied to direct the removed liquid downwardly or upwardly, as desired, to prolong or to shorten the throughput time for the liquid in the still, as desired. For example7 if it is desired to increase the throughput time of the still, the wiper slots would 'be inclined to direct the removed liquid downwardly on the rotor. Some of the liquid vaporizes and condenses on the condensing surfaces 114. The condensate falls downwardly in a thin film over` these surfaces under the iniluence of gravity, collects in the gutters 134, and is returned to the rotor surface, where it is reheated and spread in a turbulent lm over the rotor surface by the wipers. Vapor that passes upwardly to the dome is condensed on the cooled inner surface of the dome, and the condensate 9 collects in the ring 96, and is recovered as a product fraction.

While the invention has been described in connection with several specific embodiments thereof, it will be understood that it is capable of further modification, and that this application is intended to cover any variations, uses, or adaptations of the invention following, in general, the principles of the invention and including such departures from the present disclosure as come within known or customary practice in the art to which the invention pertains and as may be applied to the essential features herein before set forth, and as fall within the scope of the invention or the limits of the appended claims.

Having thus described my invention, what I claim is:

1. Apparatus for the distillation of liquid comprising a body having a chamber that is formed with an internal surface of revolution having an upright axis, means for supplying liquid to said surface to flow downwardly thereover in a film under the influence of gravity, means for heating the liquid in said film to vaporize at least a part thereof, a frame mounted for rotary relative movement with respect to said surface of revolution about an axis that is within said surface, said frame being formed with a plurality of condensing surfaces that extend generally axially of said surface of revolution and that are characterized by substantially uniformly shaped sections in transverse planes and that are formed to return condensate that forms on a condensing surface to said surface of revolution by liquid iiow on said condensing surface, guide means mounted on said frame intermediate said condensing surfaces respectively, and an elongate wiper element mounted for sliding, guided engagement of substantial radial extent with said guide means for radial movement relative to said surface of revolution through a radially-extending path at a constant orientation to said surface of revolution, constantly to present thereto one radially outer face, said element being mounted to e gage said surface of revolution upon rotary relative movement between said frame and said surface of revolution and being formed at its said face with radially projecting lands and with recesses between said lands, said element and its said lands and recesses having substantial angular extent relative to said surface of revolution thereby upon relative rotary movement between said frame and said surface of revolution to engage said surface of revolution over broad bearing areas and to provide elongate chambers between said lands, whereby said wiper element can operate to remove said iilm at the leading edges of said lands, pass the removed liquid into said chambers to mix it therein, and discharge it from said chambers respectively at a plurality of axially spaced locations on said surface of revolution again to form a film to flow downwardly under the inliuence of gravity.

2. Apparatus in accordance with claim l wherein said condensing surfaces are angularly spaced relative to each other and are characterized by substantially uniform curvilinear sections and are generally concave in transverse section relative to said surface of revolution.

3. Apparatus in accordance with claim l wherein said condensing surfaces are curved and are characterized by substantially uniformly curvilinear sections and are generally concave in transverse section relative to said surface of revolution in planes that are perpendicular to the axis of said surface of revolution at successive points along said axis, and are generated about axes that are equally radially-spaced respectively from the axis of said surface of revolution and that are equiangularly spaced from each other.

4. Apparatus in accordance with claim l wherein said frame is mounted for rotation relative to said surface of revolution and said wiper element is mounted to engage said surface of revolution under centrifugal force upon rotation of said frame. y

5. Apparatus for the distillation of liquid comprising a body having a chamber that is formed with an internal surface of revolution having an upright axis, means for supplying liquid to said surface to flow downwardly thereover in a film under the influence of gravity, means for heating the liquid in said film to vaporize at least a part thereof, a frame mounted within said chamber for rotary movement relative to said surface of revolution about an axis that is generally co-axial with the axis of said surface of revolution, said frame being formed with a plurality of axially-extending angularly spaced curved condensing surfaces that are characterized by substantially uniformly shaped sections and that are generally concave in planes that are perpendicular relative to the axis Vof said surface of revolution at successive points along said axis, and that have axially-extending radial extremities that are disposed substantially uniformly closely adjacent said surface of revolution, and said condensing surfaces being formed to return condensate that is formed on a condensing surface to said surface of revolution by liquid iiow over said condensing surface, a plurality of channel members mounted in generally axially-extending relation on said frame between adjacent condensing surfaces respectively, with the open mouths of said channels confronting said surface of revolution, and a column of wiper elements mounted in each of said channels, each column comprising a plurality of Wiper elements that are mounted one above the other and each of which has an axial length that is less than the axial length of said surface of revolution, each of said wiper elements being free to move radially independently of said other elements, and having axially-extending side faces that are disposed in sliding engagement with the side faces of the channel member in which it is mounted for presentation of said wiper element to said surface of revolution at a constant orientation, each said element being mounted to engage said surface of revolution upon rotary relative movement between said frame and said surface of revolution and being founed with radially outwardly projecting lands and with recesses between said lands, each element and its said lands and recesses having substantial angular extent thereby upon rotary relative movement between said frame and said surface of revolution to engage said surface of revolution over broad bearing areas and to provide elongate chambers between said lands, Whereby said wiper elements can operate to remove the film from said surface of revolution at the leading edges of said lands, pass the removed liquid into said chambers to mix it therein, and

discharge it from said chambers respectively at a plurality` of axially spaced locations on said surface of revolution again to form a film to flow downwardly under the iniiuence of gravity.

6. Apparatus in accordance with claim 5 wherein said frame is mounted for rotation relative to said surface of revolution and said wiper elements are mounted for radial movement independently of each other under centrifugal force to engage said surface of revolution upon rotation of said frame.

7. Apparatus in accordance with claim 6 wherein said slots of said wiper elements are downwardly and rearwardly inclined relative to said surface of revolution and to the direction of movement of said frame respectively, to impart to the removed liquid in said elongate chambers a velocity having a component in an axially downward direction on said surface of revolution, thereby to accelerate movement of liquid axially over said surface of revolution.

8. Apparatus for the fractional distillation of liquid comprising a body having a chamber that includes a fractionating zone and a product recovery zone, said fractionating zone including at least a part of said chamber that is formed with an internal surface of revolution having an upright axis, means for supplying liquid to said surface to liow downwardly thereover in a film under the influence of gravity, means for heating the liquid in said lm to vaporize at least a part thereof, a frame mounted in said fractionating zone for rotary movement relative to said surface .of revolution about an axis that is within said surface, said frame being formed -with a plurality of condensing surfaces for condensing partially the vapor in s-aid fractionating zone, said condensing surfaces extending axially of said surface of revolution and being characterized by substantially uniformly shaped sections in transverse planes and that are disposed to return condensate that forms on a condensing surface to said surface of revolution by liquid flow of said condensate over said condensing surface, to provide for repeated condensation and vaporization in said fractionating zone, guide means mounted on said frame intermediate said condensing surfaces respectively, elongate Wiper elements mounted intermediate said condensing surfaces respectively for sliding, guided engagement of substantial radial extent with said guide means for radial movement relative to said surface of revolution at a constant orientation to said surface of revolution, constantly to present thereto one radially outer face, each of said elements being formed to engage said surface of revolution upon rotary relative movement between said frame and said surface of revolution and being formed at its said radially outer face with radially projecting lands and with recesses 4between said lands, said element and its said lands and recesses having substantial f angular extent thereby upon rotary relative movement between said frame and said surface of revolution to engage said surface of revolution over broad bearing areas and to provide elongate chambers between said lands, whereby said wiper elements can operate to remove said film at the leading edges of said lands, pass the removed liquid into said chambers to mix it therein, and discharge it from said chambers respectively at a plurality of axially spaced locations on said surface of revolution, again to form a film to flow downwardly under the influence of gravity, a second condenser disposed in said recovery zone and spaced from said first condenser for condensing vapor from said fractionating zone, and means for recovering the condensate that is condensed on said second condenser.

9. Apparatus for the fractional distillation of liquid comprising a body having a chamber that includes a fractionating zone and a product recovery zone, said fractionating zone including at least a part of said chamber that is formed with an internal surface of revolution having an upright axis, means for supplying liquid to said surface to flow downwardly thereover in a film under the infiuence of gravity, means for heating the liquid in said film to vaporize at least a part thereof, a frame mounted within said fractionating zone for rotary movement relative to said surface of revolution about an axis that is generally 1 co-axial with the axis of said surface of revolution, said frame being formed with a plurality of condensing surfaces that extend generally axially of said surface of revolution and that are characterized by substantially uniformly shaped sections in transverse planes and to return con; densate that forms on a condensing surface to said surface of revolution by liquid flow over said condensing surface, channel mem-bers mounted on said frame intermediate said condensing surfaces respectively to extend generally axially relative to said surface of revolution, said channel members being disposed with the open portions of their channels respectively confronting said surface of revolution, columns of wiper blades mounted in said channel members respectively, each of said columns comprising a vertically arranged series of superposed wiper blades each o-f which has an axial extent less than the axial length of said surface of revolution, the blades in each column having opposite sides engaging the sides of the associated channel member in sliding relation over areas of substantial radial extent and being mounted for radial movement independently of each other to engage that surface of revolution at a constant orientation upon relative rotary movement between said frame and said surface of revolution, each of said blades being formed with radially projecting lands and with recesses between said lands, said lands and said recesses having substantial angular extent to engage said surface of revolution over broad bearing areas and to provide elongate chambers between said lands, whereby said wiper blades can operate to remove said film at the leading edges of said lands, pass the removed liquid into said chambers to mix it therein, and discharge it from said chambers respectively at a plurality of axially spaced locations on said surface of revolution again to form a film to fiow downwardly under the influence of gravity, a second condenser disposed in said recovery zone above said first condenser for condensing vapor from said fractionating zone, and means for recovering the condensate that is condensed on said second condenser.

l0. Apparatus in accordance with claim 9 in which said frame is'mounted for rotation relative to said surface of revolution and said wiper blades are mounted to engage said surface of revolution under centrifugal force upon rotation of said frame.

11. Apparatus in accordance with claim 9 wherein said condensing surfaces vare curved and are characterized by substantially uniformly curvilinear transverse sections that are generally concave relative to said surface of revolution in planes that are perpendicular to the axis of rotation of said frame at successive points along said axis and that are generated about axes that are equally radially-spaced from said axis of rotation and that are equiangularly spaced from each other.

l2. A method for the fractional distillation of liquid comprising applying said liquid to at least a part of an internal surface of drevolution having an upright axis to flow downwardly thereover in a film under the infiuence of gravity, heating the liquid in said film -to vaporize at least a part thereof, partially condensing the vapor, returning the condensate to said surface for reheating thereof, continuously positively mechanically engaging on said surface o-f revolution axially-spaced bearing areas that have substantial axial extent and that have an angular extent that is substantial but that represents but a fraction of the angular extent of said surface of revolution, with the slotted faces of a column of independently radiallymovable wiping blades, rotating said column relative to said surface to remove the film from said surface at the leading edges of said blades, continuously collecting the removed material in the slots in said blade faces, continuously reapplying the removed material from said slots onto said surface of revolution, again to fiow downwardly over l said surface in film form, condensing the evolved vapor in an upperzone, and recovering as a product fraction `the vapor that is condensed in said upper zone.

13. A method for the fractional distillation of liquid comprising applying said liquid to at least a part of a surface of revolution having an upright axis to ow downwardly thereover in a film under the influence of gravity, heating liquid in said film to vaporize at lea-st a part thereof and to cause the vapor vto travel ifrom said film with a component in an upward direction relative to said surface of revolution in a generally upward path between said surface of revolution and a curved condensing surface that extends axially of said surface of revolution and that is generally concave in transverse section relative to said surface of revolution and that has axially extending radial extremities that are disposed closely adjacent said surface of revolution, partially condensing the vapor on said condensing surface, rotating said condensing surface about an axis that is generally coaxial with the axis `of said surface of revolution to cause said condensing surface to move relative to said surface of revolution thereby centrifugally to impel the condensate on said condensing surface to flow over said condensing surface to said surface of revolution, continuously positively mechanically engaging on said surface of revolution axially-spaced bearing areas that have substantial axial extent and that have an angular extent that is substantial but that represents but a fraction of the angular extent of said surface i i l l revolution, with the faces of a column of rotary, independently radially-movable wiping blades, whose said faces are formed with slots that are uniformly downwardly inclined relative to the surface of revolution and to the direction of rotation thereof, rotating said column relative to said surface of revolution to remove the film from said surface of revolution at the leading edges of said blades, continuously collecting the removed material in the slots in said blade faces, continuously reapplying at least a portion of the removed material from said slots onto said surface of revolution, againt to flow downwardly in iilm form, condensing the vapor in an upper Zone above said condensing surface, and recovering as a product fraction the vapor that is condensed in said upper zone.

14. Apparatus for the disillation of liquid comprising a body having a wall that is formed to dene an internal surface of revolution, means for supplying liquid to said surface to ow downwardly thereover in a tilm under the influence of gravity, a heating jacket secured to the external surface of said wall to heat the liquid in said lrn to vaporize at least a part thereof, a frame mounted for rotary relative movement with respect to said surface of revolution about an axis that is generally coaxial with the axis of said surface, said frame being formed with a plurality of condensing surfaces that extend generally axially of said surface of revolution and that are characterized by substantially uniformly shaped sections in transverse planes and that can function together as a condenser to condense vapor evolved from said film and to return condensate that forms on a condensing surface to said surface of revolution by liquid ow over said condensing surface, means mounted on said frame intermediate said condensing surfaces respectively, an elongate wiper element mounted for sliding, guided engagement of substantial radial extent with said guide means for radial movement relative to said surface of revolution at a constant orientation to said surface of revolution, constantly to present thereto one radially outer face, said wiper element being formed to engage said surface of revolution upon relative rotary movement between said frame and said surface of revolution and being formed at its said face with radially projecting lands and with recesses between said lands, said element and its said lands and recesses having substantial angular extent thereby upon relative rotary movement between said frame and said surface oi revolution to engage surface or' revolution over broad bearing areas and to provide enlongate chambers between said lands, whereby said Wiper element can operate to remove said film at the leading edges of said lands, pass the removed liquid into said chambers to mix it therein, and discharge it from said chambers respectively at a plurality of axially spaced locations on said surface of revolution again to form a film to flow downwardly under the influence of gravity, and means connecting said heating jacket and said condenser in a closed thermal circuit for circulating a heat exchange fluid therethrough to release heat in said heating jacket and to absorb heat in said condenser.

References Cited in the le of this patent UNlTED STATES PATENTS 2,306,265 Heald Dec. 22,1942 2,500,900 Madlen Mar. 14, 1950 2,546,381 Zahrn Mar. 27, 1951 2,562,153 Taylor July 24, 1951 2,619,814 Kniel Dec. 2, 1952 2,749,292 Perry et al June 5, 1956 2,766,193 Schneider Oct. 9, 1956 2,848,388 Beuche Aug. 19, 1958 FOREIGN PATENTS 330,805 Great Britain June 19, 1930 710,158 Great Britain June 9, 1954

Claims

12. A METHOD FOR THE FRACTIONAL DISTILLATION OF LIQUID COMPRISING APPLYING SAID LIQUID TO AT LEAST A PART OF AN INTERNAL SURFACE OF REVOLUTION HAVING AN UPRIGHT AXIS TO FLOW DOWNWARDLY THEREOVER IN A FILM UNDER THE INFLUENCE OF GRAVITY, HEATING THE LIQUID IN SAID FILM TO VAPORIZE AT LEAST A PART THEREOF, PARTIALLY CONDENSING THE VAPOR, RETURNING THE CONDENSATE TO SAID SURFACE FOR REHEATING THEREOF, CONTINUOUSLY POSITIVELY MECHANICALLY ENGAGING ON SAID SURFACE OF REVOLUTION AXIALLY-SPACED BEARING AREAS THAT HAVE SUBSTANTIAL AXIAL EXTENT AND THAT HAVE AN ANGULAR EXTENT THAT IS SUBSTANTIAL BUT THAT REPRESENTS BUT A FRACTION OF THE ANGULAR EXTENT OF SIAD SURFACE OF REVOLUTION, WITH THE SLOTTED FACES OF A COLUMN OF INDEPENDENTLY RADIALLYMOVABLE WIPING BLADES, ROTATING SAID COLUMN RELATIVE TO SAID SURFACE TO REMOVE THE FILM FROM SAID SURFACE AT THE LEADING EDGES OF SAID BLADES, CONTINUOUSLY COLLECTING THE