US2578086A - High-vacuum fractionating distillation apparatus - Google Patents

Description

Dec. 11, 1951 E, s PERRY 2,578,086

HIGH-VACUUM FRCTIONATNG DISTILLATION APPARATUS Filed June 9, 1948 2 SHEETS-SHEET 2 VA GUUM RES/DUE Ely/WON@ s. PERRY IN1/ENT@ /1 TTORNE YS Patented Dec. 11, 1951 HIGH-VACUUM FRACTIONATING DISTILLA- TION APPARATUS Edmond S. Perry, Rochester, N. Y., assignor, by

mesne assignments, to Eastman Kodak Com-4v pany, Rochester, N. Y., a. corporation of New Jersey Application June 9, 1948, Serial No. 31,885

3 Claims.

This invention relates to fractional distillation under vacuum.

It is an object of this invention to provide simple, economical and effective methods and apparatus for high-vacuum fractional distillation. Another object is to provide a method of highvacuum fractional distillation in which the thermal hazard to the distilland is reduced to a minimum. A further object is to provide a highvacuum fractionating distillation method and apparatus in which a centrifugal vaporizing surface is combined with a fractionating column which allows substantially unobstructed passage of the distilling vapors. Other objects will appear hereinafter.

These and other objects are accomplished by this invention which, in a preferred embodiment, comprises a gas-tight receptacle, the upper part of which is substantially cylindrical and substantially vertical, means for evacuating said receptacle, a rotatable and heatable vaporizing surface located at the lower end of said receptacle, means for introducing distilland onto said vaporizing surface, a rotatable coaxial shaft in the upper cylindrical portion of said receptacle, a brush associated with said rotatable shaft, the bristles of said brush desirably being long enough to make contact with the surface of said receptacle, means for heating said surface, and a condensing surface located at the upper end of said receptacle. Optionally, the rotatable shaft with which the brush is associated may be cooled.

In the accompanying drawings, Figure l is a view partly in section showing apparatus embodying the present invention and including a rotatable plate vaporizing surface, a rotatable brush fractionating column in which the shaft to which the brush is connected is cooled, and a condensing surface at the top of said fractionating column.

Figure 2 is a view partly in section showing a modified form of apparatus embodying the invention and being substantially similar to Figure 1 except that the vaporizing surface is in the shape of a truncated cone, the shaft to which the brush is fastened is cooled, the condenser is separated somewhat from the fractionating column,

2 I6 extends through gas-tight bearing I8 into the lower part of vacuum chamber I5. Vaporizing surface 20 is fastened to the upper part of rotatable shaft I6. Vaporizing surface 2l)l may be rotated by means of force applied through pulley 22 on shaft I6. Vaporizing surface 20 may be heated by means of an electric current passed through heating element 24 at slip rings 25. Distilland enters the system through conduct 26 by means of which it is introduced approximately onto the center of vaporizing surface 20. Unvaporized residue collects in the bottom of the apparatus and is drawn olf the system through conduit 30. Brushes 34 are fastened to rotatable shaft 36 which passes through gas-tight bearing 38 into chamber I5 and whichis held in position at its lower end by means of spider 40, which holds bearing 42 in the center of fractionating section I2. Shaft 36 is rotated by force applied at pulley 46. An electric current may be passed through heating element 44 to maintain the sides of fractionating column 32 at an elevated temperature. Material which has vaporized upon plate 20 passes upward through brushes 34 and is condensed on the upper part of fractionating section I2, which is cooled by cooling coils 48. Condensate ows by gravity into alembic 50 and is drawn off by means of conduit 52. Shaft 36 may be cooled by forcing fluid through conduit In the embodiment shown in Figure 2, shaft 36 is cooled by means of air blown through shaft 54. Condenser 56 is separated from fractionating tower 32 by conduit 58, which is preferably of considerable cross-sectional area. Condenser 56 is cooled by water introduced through conduit 60 and drawn off through conduit 62. Distilland is introduced to the center of column 32 through conduit 26. A portion of the distilland is vaporized upon coming into contact with the heated interior surface of column 32. An undistilled portion collects in gutter 64, from whence it passes through conduit 66 to vaporizing surface 20. A portion of the distilland residue is here vaporized.v Annular skirt 29 guides the vapors toward the fractionating column. The undistilled portion collects in gutter 28 and is drawn off through conduit 30. Conduit 66 is vconnected with conduits '26 and 30 and when operated in conjunction with pump 68 serves as a means of reintroducing a portion of the residue to the in coming distilland. Distillate is withdrawn from the bottom of condenser 56 by means of conduit 52.

In the embodiment shown in Figure l, the

condensing surface is cooled by cooling coil 48 but for many distillations a blast of air blown at the cooling surface is sufcient. In Figure 2 shaft 36 was cooled by means of air blown through shaft 64, which extends to a point near the bottom of shaft 36 andwhich has' an outside diameter smaller than the inside diameter of shaft 36. Water or other cooling fluid may be substituted for air if operating conditions necessitate.

In operating the apparatus of Figure 1, the system is rst evacuated by means of vacuum pumps (not shown) attached to conduit I4. Distilland enters the vacuum chamber through conduit 26, from which it is fed to the approximate center of rotating plate 20. Rotating plate is heated by heating element 24 anda portion of the distilland is thus vaporized and passes upward toward rotating brushes 34, the undistilled residue passing to the bottom of the apparatus from which it is collected and withdrawn through conduit 30. Brushes 34 occupy a relatively small portion of the space in the fractionating column and thus the space therein is relatively unobstructed. As the brushes rotate, a portion of the vaporized distilland is condensed on cooled shaft 36 and flung outward'onto brushes 34 to the wall of the fractionating column. Since this wall is heated by element 44, the condensate is revaporized and the vapor molecules given a directional velocity in a manner substantially crosscurrent to the distilland vapors passing upn ward from plate 20. A portion of the vapors is condensed on shaft 36 and again conducted to the wall of fractionating section I2. With alternate condensation and vaporization of vapors together with a crosscurrent contact among vapors, there is a tendency for the heavier components to pass downward and the lighter components to pass upward. The lighter components are condensed on condensing surface 48, collect in alembic 60, and are withdrawn through conduit 62. In the apparatus illustrated in Fi.,- ure 2 the operation is similar to that of the apparatus in Figure 1, except that incoming distilland is fed to the center of the fractionating column, where a portion is vaporized and another portion passes downward to be picked up by gutter 64. This undistilled residue then passes through conduit 60 to rotating vaporizing surface 20. A portion of the distilland is here vaporized while a residue portion is collected in gutter 26 and withdrawn through conduit 30. Conduit 66 connects residue conduit 30 with feed conduit 26 and when operated in conjunction with pump 66 a portion of the residue may be recycled through the still with the feed mixture. Vapors from condensing surface 20 pass upward through brushes 34 as in the apparatus of Figure 1. Rotating shaft 36 is cooled as in the apparatus of Figure 1. The constant crosscurrent contact of the molecules confers considerable fractionating efficiency on this apparatus. The lighter fraction of the vapor molecules which finally rises to the top of the column passes through conduit 66 into condenser 66. Condenser 66 is cooled by a gas or liquid pumped through conduit 60 and out conduit 62. Condensate collects in the bottom of condenser v46, from which it is withdrawn through conduit 62.

4 without departing from the spirit and scope of the invention as it is defined by the appended claims.

What I claim is:

1. Fractlonating apparatus comprising in combination a generally vertical fractionating column having a closed lower end, a centrifugal vaporizer rotatably mounted in said column adjacent said closed lower end, said vaporizer having a continuous dished vaporizing surface facing upwardly into said column, heating means for said vaporizer, means for rotating said vaporizer, conduit means arranged for introducing distilland onto the inner surface of said column at a zone spaced from the lower end of said column, means for conducting distilland from a lower zone of said column onto said vaporizing surface,'means for withdrawing residue from the lower end of said column, heating means for said column arranged about substantially the extent of said column, a rotatable shaft mounted in said column and generally concentric therewith. means for positively abstracting heat from said shaft, brush means secured along said shaft and extending radially outwardly from said shaft at a plurality of axially spaced positions along said shaft into sweeping contact with said column, means for evacuating said column, and condensing means communicating with an upper zone of said column for condensing vapors ascending said column.

2. Fractionating apparatus comprising in combination a generally vertical tubular fractionating column, a vaporizer housing secured to and closing the lower end of said fractionating column, a centrifugal vaporizer rotatably mounted in said housing and having a continuous dished vaporizing surface facing upwardly into the mouth of said fractionating column, heating elements arranged to directly heat said vaporizer, means for rotating said vaporizer, means for progressively introducing distilland onto a. central portion of said vaporizing surface and including conduit means arranged for initially introducing distilland on the inner surface of said fractionating column at a zone spaced from the lower end of said column and means for conducting distilland from the lower end of said column onto said vaporizing surface, means for progressively withdrawing undistilled residue from said vaporizer housing, heating elements arranged about substantially the extent of said fractionating column, a hollow shaft rotatably mounted in said fractionating column and generally concentric therewith, means for circulating cooling fluid in said shaft, means for rotating said shaft, brush means secured along said shaft and extending radially outwardly from said shaft at a plurality of axially spaced positions along said shaft into sweeping contact with said fractionating column, means communicating with an upper portion of said column for evacuating said column and said housing, and condensing means adjacent the upper end of said column for condensing vapors ascending said column.

3. Fractionating apparatus comprising in combination a generally vertical tubular fractionating column, a vaporizer housing secured to and closing the lower end of said column, evacuating means communicating with an upper zone of said column for evacuating said column and said housing, a hollow shaft rotatably mounted in said column and generally concentric with said column, means for heating said column, means for cooling said shaft. a plurality of bristles secured to said shaft at a multiplicity of axially spaced positions along said shaft, said bristles extending radially outwardly from said shaft into sweeping contact with the inner surface of said column. means -for rotating said shaft and bristles, a centrifugal vaporizer rotatably mounted in said vaporir housing and having a continuous dished vaporizing surface directed upwardly toward the lower end of said fractionating column, means for rotating said vaporizer, heating elements arranged in direct heating relation to said vaporizer, a distilland feed conduit opening into said column at a point spaced from the lower end of said column for progressively introducing distilland on the inner surface of said column, means at the lower end of said column for progressively directing distilland flowing down said colunn from said feed .n

conduit onto a central zone of said vaporizing surface, conduit means for progressively withdrawing from said vaporizer housing undistilled REFERENCES CITED The following references are of record in the file Voi' this patent:

UNITED STATES PATENTS Number Name Date '2,343,667 Hickman Mar. 7, 1944 2,403,978 Hickman et al. July 16. 1946 is. 2.460.602 Semon Feb. 1, '1949 .2,500,900 Madlen Mar. 14. 1950 2,539,699 Perry et al Jan. 30. 1951 FOREIGN PATENTS Number Country Date 595,096 Great Britain Nov. 26, 1947 595,142 Great Britain Nov. 27. 1947 596.392 Great Britain Jan. 2. 1948

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