US2554703A

US2554703A - Vacuum still

Info

Publication number: US2554703A
Application number: US656114A
Authority: US
Inventors: Kenneth C D Hickman
Original assignee: Eastman Kodak Co
Current assignee: Eastman Kodak Co
Priority date: 1946-03-21
Filing date: 1946-03-21
Publication date: 1951-05-29
Anticipated expiration: 1968-05-29

Description

May 29, 1951 K. C. D. HICKMAN VACUUM STILL Filed March 21, 1946 T0 maul/M F1 1 f0 VACUUM PUMPS PUMPJ 2 48 34 3; HL ATERs F6 \M/wvvwwwwwvwwvwm/wOvwwwMA/wm/vwmA/ww 9 *5 AMANWVWWMNMMMWVWMMMMNWMMMAMNW] LD/ST/LLAND IN 34 4 \HEATERJ 38 I 44 D/577LLATE 4 24 our D/577LLATE our FIG Z.

o o 34 0 I H54TER$ 0 o REFLECTOR IENNETH. C.D.HIC

INVENTOR 33 ATTORNEY Patented May 29, 1951 VACUUM STILL Kenneth C. D. Hickman, Rochester, N. Y., as-

signor, by mesne assignments, to Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey Application March 21, 1946; Serial No. 656,114

3 Claims.

This invention relates to improvements in vacuum distillation'apparatus, particularly of the type wherein high vacuum exists between the vaporizing and condensing surfaces.

It is known to distill decomposable substances under vacuum conditions such that a relatively high Vacuum exists between the vaporizing and condensing surfaces. This is accomplished by having a relatively unobstructed space for the flow of vapors from the vaporizing to the condensing surface. In constructions heretofore used, this has necessitated the placing of the condensing surface opposite the heated vaporizing surface which resulted in considerable loss of heat from the hot vaporizing surface to the cold condensing surface. Also, it is usual practice in this art to form the distilland into a thin film, supported by a heated vaporizing surface. Since the vaporization takes place only from the surface of the film opposite from the supporting heated surface, the heat of vaporization reached the actual point of vaporization only by passage through the film of distilland. The portion of this film adjacent the vaporizing surface was, therefore, overheated in order to deliver sufficient heat to the portion of the film undergoing vaporization. This results in enhanced thermal decomposition in the layer next to the support.

This invention has for its object to overcome the above difficulties. Another object is to provide improved vacuum distillation apparatus in which the loss of heat is reduced to an important extent. Another object is to provide improved vacuum distillation apparatus which will reduce the thermal gradient in the film of distilland while it is undergoing distillation. A still further object is to reduce the thermal gradient in the distilling film. Other objects will appear hereinafter.

These and other objects are accomplished by my invention which includes a vacuum still having a rotatable approximately cylindrical vaporizing surface with a condensing surface positioned at an open end thereof.

In the following description I have given certain preferred embodiments of my invention but it is to be understood these are set forth by way of illustration and not in limitation thereof.

In the accompanying drawings, Fig. 1 is a vertical section of an improved vacuum still embodying the features of my invention and Fig. 2 is a vertical section taken at right angles to Fig. l and on line 2-2 of Fig. 1.

Referring to'the drawings, numeral 4 designates a cylindrical shell closed at one end by an integral plate 6 and at the opposite end by a removable plate 8 which makes a gas-tight connection with shell 4 by means of a gasket ii) placed between the bolted flanges 22 and I4. Numeral l6 designates a shaft positioned centrally within cylindrical shell 4 and rotatably mounted in bearings l8 and 20. Bearing 2B is provided with a suitable gas-tight packed gland 22. The shaft is rotated by power applied to pulley 24. Numeral 26 designates a cylindrical vaporizing surface mounted upon shaft 29 and concentric therewith. Numeral 2? designates supporting members which maintain the cylindrical vaporizing surface 26 in the position shown and which are integral with shaft It. The ends of cylinder 26 are turned inwardly as indicated by the numerals 28 and 30. I

vaporizing cylinder 26 is surrounded by a plurality of heating elements 32 and by a cylindrical reflector 34 which is preferably highly polished on the inside surface to reflect heat from elements 32 onto the outside of cylinder 26. Numeral 36 designates a conduit for introducing distilland onto the inside surface of vaporizing cylinder 26 and numeral 38 designates a conduit for removing undistilled residue accumulating at the end of vaporizing cylinder 26.

The cylindrical shell 4 is provided with an annular collar All and 42 at each end thereof. These annular collars serve in conjunction with the

end plates

6 and 8 to form gutters at each end of the shell in which distilland is collected.

Numerals

44 and 46 designate conduits through which liquid is withdrawn from these gutters. Numeral 48 designates conduits to which are connected backing pumps (not shown) for evacuating the still shell. 1

In operating the apparatus, material to be distilled is introduced through conduit 36 onto the inside surface of vaporizing cylinder 25. Shell d is evacuated and shaft it is caused to rotate by force applied to pulley 24 and electric heating elements 32 are actuated to heat surface 26 to distilling temperature. The distilland is caused to flow by centrifugal force in a thin film over the inside surface of cylinder 25. This film is heated to distillation temperature and the vapors which are generated pass toward the ends of the cylinder 26. Since the lowest boiling components would be vaporized first they would pass outwardly through the left hand end of cylinder 26 and would condense on the air cooled end plate 6. The condensate would run to the bottom of the gutter formed by collar to and would be with-- drawn through conduit 44. The higher boiling portions of the distilland would be vaporized toward the right hand end of the cylinder 26 and would pass through the right hand end and into contact with air cooled end plate 8 where they would be condensed, flow to the bottom of the gutter, formed by collar 42, and would be withdrawn as a high boiling fraction through conduit 46. Undistilled residue would be forced into the end of conduit 38 by the direction of rotation, as indicated in Fig. 2 and this undistilled residue would be withdrawn from the still in this manner. Reflector 34 serves to concentrate the heat on the vaporizing surface 26.

Instead of introducing the distilland at one end of the vaporizing cylinder 26 and thus separating two fractions, it would be advisable in some cases to introduce it at other points in the cylinder, in which case there would not be as great a difference in the distilling temperature of the fractions obtained orthey would be identical if introduction took place at the middle of the cylinder.

Since the vaporizing surface is cylindrical and there is no opposing condensing surface, the loss of heat is materially reduced, At the same time substantially unobstructed space for the flow oi vapors to the condensing surface is provided. Each unit of the vaporizing surface is opposite another heated unit of the vaporizing surface so that any radiation of heat which does take place is utilized by the opposite unit of the vaporizing surface. This heat is applied at the outside of the distilling film and this avoids the necessity of introducing excess heat to the portion of the film adjacent the heated support, as in prior constructions. Ihe thermal gradient through the distilling film and its attendant thermal. decomposition is thus reduced.

What I claim is:

1. Vacuum distillation apparatus comprising a gas-tight chamber having a horizontally disposed cylindrical side wall and vertically disposed end walls, evacuating means for said chamber, an open-ended cylindrical evaporating member disposed horizontally in said chamber and generally concentrically therewith, the ends of said evaporating member'being spaced from the end walls of said chamber and being turned inwardly to provide a peripheral lip at each end of said evaporating member, a rotatable shaft extending'axially through said evaporating member and carrying said evaporating member for rotation therewith, means for rotating said shaft, a cylindrical heatrefiecting member positioned around substantially the extent of said evaporating member and generally concentric therewith, radiant heating means disposed about said evaporating member between said evaporating member and said heatrefiecting member, conduit means arranged to introduce material to be distilled onto the inner surface of said evaporating member, secondary conduit means spaced from said first-named condui't means and arranged to withdraw undistilled residue from the inner surface of said evaporating member, projecting members extending inwardly from said side wall adjacent each said end wall of saidchamberand forming with said end walls gutters for collecting distillate condensing on said end walls, and conduit means arranged for withdrawing distillate from said gutters.

2. Vacuum distillation apparatus comprising generally horizontally disposed cylindrical side wall means and generally vertical end wall means forming a gas-tight chamber, evacuating means for said chamber, an open-ended vaporizing cylinder rotatably mounted in said chamber and generally concentric therewith, the ends of said cylinder being spaced from said end wall means, means for rotating said cylinder, heating means positioned around said vaporizing cylinder and arranged to heat said vaporizing cylinder to distilling temperature, said heating means being spaced from said end wall means and out of heating relation therewith, whereby said end wall means form condensing surface means for distilling vapors issuing from said vaporizing cylinder, conduit means arranged to introduce material to be distilled onto the inner surface of said vaporizing cylinder, secondary conduit means spaced from said first-named conduit means and arranged to withdraw undistilled residue from said vaporizing cylinder, gutter means arranged to collect condensate from said end wall means, and conduit means for withdrawing condensate from said gutter means.

3. Vacuum distillation apparatus comprising wall means forming a gas-tight chamber, means for evacuating said chamber, a generally horizontally disposed open-ended vaporizing cylinder rotatably mounted in said chamber, the interior of said cylinder being substantially unobstructed, the ends of said cylinder being spaced from said wall means, means for rotating said cylinder, a heat reflector positioned about substantially the extent of said vaporizing cylinder, heating means disposed between said heat reflector and said vaporizing cylinder, means for introducing distilland on. the inner surface of said vaporizing cylinder, means spaced from said last-named means for removing undistilled residue from the inner surface of said vaporizing cylinder, and gutter means arranged to collect condensate condensing on said wall means.

KENNETH C. D. HICKMAN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 27,503 Willard Mar. 13, 1860 440,752 Borotte Nov. .18, 1890 552,456 'Theisen Dec. 31, 1895 1,286,315 Heuser Dec. 3, 1918 2,220,171 Woaillon Nov. 5, 1940 2,224,621 Voorhees Dec. 10, 1940 2,234,166 Hickman Mar. 11, 1941 2,385,074 Guignard Sept. 18, 1945 2,427,718 Denys Sept. 23, 1947 2,437,594 Denys 1 Mar. 9, 1948 FOREIGN PATENTS Number Country Date 11,350 Great Britain of 1889