US2364360A - High vacuum distillation process and apparatus - Google Patents

Description

. 5, 1944. K. c. D; HICKMAN HIGH VACUUM DISTILLATION PROCESS .AND APPARATUS Filed March 23, 1942 2 Sheets-Sheet 1 INgOR A 'I'TO RNE YS KENRIETH ab. HICKMAN 1944- K. c. D. HICKMAN 2,364,350

HIGH VACUUM DISTILLATION PROCESS AND APPARATUS Filed March 28, 1942 2 Sheets-Sheet 2 150 14 11o 1 142134 14 12 m I ($1 15 '"'"'""""':z:::'"::g"' ////A I A 112 1Z6 IIEMVE T H 'C.D.HICIQ1AN INVENT OR W. W BY 64W ATTORNEYS Patented Dec. 5, 1944 HIGH VACUUM DISTILLATION PROCESS AND APPARATUS I Kenneth C. D. Hickman, Rochester, N. Y., as-

signor to Distillation Products, Inc., Rochester, N. Y., a corporation of Delaware Application March 28, 1942, Serial No 436,646

v 4 Claims.

This invention relates to improved high vacuum centrifugal stills and in particular high vacuum stills in which the condensing and vaporizing surfaces both rotate.

High vacuum centrifugal stills are described and are well known in the prior art; see, for instance, my Patent 2,210,927, August 13, 1940. In such stills the distilland is introduced onto the approximate center of a rotating plate and is caused to flow thereover in a thin film by centrifugal force. The vapors are condensed upon the condensing surface which likewise may rotate in which case the condensate on the rotating condensing surfaceis thrown to the periphery by centrifugal force. It has been proposed to heat such stills by radiation from electrically heated resistance units or by circulation of a heated liquid in contact with the vaporizing surface. It will be realized that heating of a rapidly rotating disc in a high vacuum is a rather difllcult problem to solve. The above-mentioned heating expedients have not been completely satisfactory for various reasons. Electricity is a good heating means but it is very expensive; also, the heating resistance units are expensive. When heating with a low vapor pressure liquid forth for the purpose ofillustration and not in limitation thereof,

In the accompanying drawings wherein like numbers refer to like parts, I have illustrated two of the preferred embodiments of my invention wherein:

Fig. 1 is a vertical section of a centrifugal still provided with a single vaporizing and condensing surface embodying the principles of my invention.

Fig. 2 is a vertical section ofsa multl-unit still embodying the improved construction of my invention and v it hasbeen found that certain dilficlllties are encountered due to vapors given off by the heated liquid. They not only tend to lower the pressure in the stills, but also contaminate the materials being distilled.

This invention has for its object to provide a cheap and eflicient method of heating high vacuum centrifugal stills. Another object is to provide improved high vacuum centrifugal process and apparatus. A still further object is'to provide high vacuum centrifugal stills which can be heated by combustion. Other objects will appear hereinafter.

These and other objects are accomplished by my invention which includes high vacuum distillation process and apparatus in which the condensing and vaporizing surfaces form an integral rotatable unit and are both exposed to approximately atmospheric or higher pressure On one,

side and a high vacuum on the other side, heat being applied to the vaporizing surface on the Fig. 3 is a vertical section of a multi-unit still similar to that shown in Fig. 2 but illustrating alternative methods for removal of liquids from the still.

Referring. to Fig. 1, numeral 4 designates a circular vaporizing plate the center of which protrudes outwardly at 6. Numeral 8 designates a similarly shaped-condensing surface which is integral with vaporizing plate 4 and makes gastight connection therewith at flange ill. Numerall2 designates a conduit which is connected to the approximate center of condenser 8 and integral therewith. Conduit I2 is rigidly mounted in bearing l4 and supporting bearing IS in the manner illustrated. Numeral I8 designates a pulley integral with conduit l2 through which power is applied to rotate the conduit I2, condensing plate 8 and vaporizing plate 4 as an integral unit. Numeral 20 designates a stationary conduit which connects to a backing pump (not shown). Numeral 22 designates a flange at the end of conduit l2 which is provided with a ground joint 24. Stationary conduit 20 is likewise provided with a similar ground joint also indicated by numeral 24. Numeral 26 designates a stationary collar fixed to conduit 20 in a gastight manner at joint 21 and is provided with a sealed packing 28. The space between the collar 26 and flange 22 is fllled with a low vapor pressure sealing compound.

sation pump. Numeral 32 designates the working fluid and the boiler. Numeral 34 designates side exposed to the atmospheric or like pressure.

My invention also includes a rotating high vacuum distillation process and apparatus in which the rotation causes removal of liquids therein against atmospheric pressure.

In the following description I have given several of the preferred embodiments of my invention, but it is to be understood that these are set the high pressure jet of the condensation pump, and numeral 36 the openings in the chimney 30 through which pump fluid flows into jet 34.. Numeral 38 designates the low pressure jet of the condensation pump and numeral 40 the openings through which pump fluid vapors pass from the chimney into the jet 38. Numeral 42' desi nates an annular gutter mounted upon the inside wall of conduit l2. Numeral 44 designates designates a liquid seal conduit which communicates at one end with the inside of the still at a point immediately below flange 48,'the other end of which terminates in gutter 58. Numeral 60 designates a conduit for withdrawing liquid from conduit 58. Letter a designates the head of liquid which accumulates in the withdrawal conduit-50 and which would be required to force liquid from the still during operation. Numeral 66 designates a plurality of gas burners supplied with gas through conduit 68, the flames impinging upon the outside surface of vaporizing plate 4. Numeral I designates a combustion chamber or chimney serving to conserve the heat generated by burners 66 and to remove combustion products.

Referring to Fig. 2, numeral 90 designates an annular collar which joins still units A and B into one integral unit. Stills A and B are constructed in a manner very similar to that illustrated in Fig. 1. Numeral 92 designates an annular gas burner which surrounds collar 90. Numeral 94 designates a furnace or chimney structure of rectangular cross section the walls of which come into close proximity with the outside'periphcry of stills A and B. Numeral 96 designates a relatively low vapor pressure heating fluid such as mercury.

Referring to Fig. 3, numeral I02 designates a withdrawal conduit to remove undistilled residue from the space between the periphery of the vaporizing surface 44 and the separating collar 48. Numeral I04 designates a withdrawal conduit for removing condensate from the periphery of condensing surface 8. This condensate collects at the periphery and is prevented from mixing with undistilled residue by separating collar 48.

Numeral I06 designates a reciprocating pump,

connected to conduit I02 and numeral I08 desi nates a conduit connected to the exhaust side of said pump. Conduit I08 terminates in an annular gutter IIO which is stationary. -Numeral II2 designates a withdrawal conduit to remote liquid from gutter IIO. Numeral I I4 designates a stationary eccentric cam and numeral I I6 des ignates a shaft which is reciprocated by revolving around the stationary eccentric cam II4. This reciprocation actuates pump I06. Numeral II8v designates a reciprocating pump similar to I06, which is similarly actuated by shaft I20 and stationary cam II4. Numeral I22 designates a conduit connecting to the exhaust side of. pump H8 and terminating inside stationary gutter I24. Numeral I26 designates a withdrawal conduit for removing liquid from stationary gutter I24.-

Numeral I30 designates a rotary pump the intake side of which is connected to conduit I04 and the exhaust side of which is connected to conduit I32. Conduit I32 terminates inside stationary gutter I34 to which gutter is connected a withdrawal conduit I36. Numeral I38 designates a shaft which actuates rotary pump I 30.

opposite pump I30 which meshes with stationary gear l42. During rotation of the still, gear I42 remains stationary and thus gear I40 is caused to rotate shaft I38 and in turn actuate pump I30. Numeral I46 designates a rotary pump similar to pump I30. The intake side of this pump is connected to conduit I02 and the exhaust side is connected to conduit I48 which terminates inside stationary gutter I50. Numeral I52 designates a withdrawal conduit connected to gutter I50. Numeral I54 designates a shaft which during operation actuates pump I46 by gear I58 meshing with stationary gear I42.

In operating the apparatus illustrated in Fig. 1 it is first necessary to introduce sufficient liquid into the still on each side of partition 48 to fill the liquid seal in conduits 50 and 56. The entire still unit is then rotated by force applied to pulley I8. Rotation causes the liquid introduced into the still to fill the liquid lock or sealed portions of conduits 50 and 56. The evacuating pumps are then put into operation. The backing pump (not shown) connected to conduit 20 is first startel and then the working fluid 32 in the boiler is vaporized by heat from resistance heater 3|. The vapors pass upward through openings 36 and 40 and are then deflected downward through jets 38 and 34. Gases in the still are entrained in these vaporjets and are pushed downward and are eventually removed by the backing pump connected to conduit 20. Condensed vapor from these jets flows into gutter 42 through conduit 44 and thence back into boiler 30.

Liquid to be distilled is introduced through conduit 46 into depressed portion 6 of vaporizing plate 4. The entire surface of plate 4 is then heated by burners 66 to distillation temperature. The liquid flowing through conduit 46 is thrown by centrifugal force in the form of a thin film over the surface of vaporizing plate 4. Undistilled resdue flows into conduit 50 and is then flung into conduit 52, the speed of rotation being suflicient to throw the liquid out of the still as explained in detail below. Vapors derived from the film of distilland condense on the inside surface of condenser 8, which is air cooled. This condensate is then flung by centrifugal force to the periphery of plate 8 and is compelled to flow by flange 48 into conduit 56 from which the condensate is thrown into gutter 58 and removed therefrom by way oLconduit 60. Undistilled residue accumulates in gutter 52 and is withdrawn by way of conduit 54.

This shaft is provided with a gear I 40 at the end The amount of liquid head which must accumulate in conduit 50 or analogous conduit 56 will depend upon the speed of rotation and the diameter' of the still. It is necessary that the centrifugal force applied to the head, i. e., the liquid between the points indicated by the letter a Fig. 1 be slightly in excess of the atmospheric pressure. This can be determined in a simple manner by any skilled physicist. For a plate having a diameter of about 32 inches and a speed of rota-j tion of about 1000 R. P. M. a head of about 6cm. would be desirable although a slightly smaller' head could be used.

In operating the apparatus illustrated in Fig;

2, the still unit A and B is rotated by force applied through pulley I8 and the Withdrawal conduits 50 and 56 are filled with liquid as described in connection with Fig. 1. Liquid to be distilled is introduced through conduit 46 and burners 82 are put into operation. 8 The stills are evacuated.

by suitable pumps connected to conduits 20. Distillation takes place as described in connection .with Fig. 1 in both stills A and B. Heating of method of Withdrawing distillate and undistilled residue from the still. In Fig. 3 the undistilled of gutter H and is withdrawn through conduit H2. Rotary Withdrawal pump I46 is actuated through conduit I48 into stationary gutter I50 from which it is withdrawn through conduit I52.

Pumps H8 and I30 serve to withdraw condensate from stills A and B respectively. Pump 0 withdraws the condensate through conduit I04 and forces it through conduit I22 into stationary gutter I24 from which it is withdrawn through conduit I26. Pump H8 is actuated by reciprocation of shaft I which is caused to reciprocate by traveling over the outside surface of eccentric cam II4 which is stationary. Rotary pump I30 is actuated by rotation of shaft I38 which is caused t g rotate by gear I40 meshing with stationary gear rflr The liquid pumped out of the still by pump I30 is forced through conduit I32 into stationary gutter I32. The liquid collecting in gutter I32 is withdrawn through conduit It will thus be seen that I have provided a high vacuum centrifugal still in which the centrifugal surface is exposed to pressures approximately the same as or greater than atmospheric and in which heating is a simple problem. Application of combustion gases or other cheap heating media can be made without encountering problems heretofore encountered in connection with the supplying of heat to a rotating surface in a h gh vacuum. The stills can be disposed in series in a tall furnace one above the other; the distilland first being introduced into the top still of the series. This still would naturally be at the lowest temperature and would remove the lowest boiling fraction. The undistilled residue would then flow in sequence down through the stills and would eventually be withdrawn from the still positioned at the lowest point in the furnace which still would be at the highest temperature.

What I claim is:

1. High vacuum centrifugal distillationappa' means for introducing distilland onto the approximate center of and means for removing residue from the periphery of that side of the vaporizing surface which is not exposed to approximately atmospheric pressure and means for removing distillate from that side of the condensing surface which is not exposed toatmospheric pressure. I

2. High vacuum unobstructed path centrifugal distillation apparatus comprising vaporizing and condensing surfaces of circular shape, co-operating to form approximately parallel walls of a vacuum tight unobstructed casing and adapted to be rotated about a common axis, means for rotating the surfaces in an environment which is at approximately atmospheric pressure, means for applying heat to thatside of the vaporizing surface exposed to atmospheric pressure, an evacuating port surrounding the axis of rotation for maintaining a high vacuum in the space between sides of the condensing and vaporizing surfaces not exposed to atmospheric pressure, means for introducing distilland onto the approximate center of and means for removing residue from the periphery of that side ofthe vaporizing surface which is not exposed to atmospheric pressure, and means for removing distillate from that side of the condensing surface which is not exposed to atmospheric pressure. I

3. High vacuum unobstructed path distillation apparatus comprising vaporizing and condensing surfaces of circular shape co-operating to form the walls of a vacuum tight still casing and adapted to be rotated about a common axis,

means for rotating the surfaces in an environment which is at approximately atmospheric pressure, means for applying hot gases to that side of the vaporizing surface exposed to atmospheric pressure, an evacuating portat the axis of rotation for maintaining a high vacuum in the space between those sides of the condensing and vaporizing surfaces not exposed to' atmospheric pressure, means for introducing distilland onto the approximate center of and means for removing residue from the periphery of that side of the vaporizing surface which is not exposed to atmospheric pressure, means for removing lll'1- distilled residue from the periphery of the vaporizing surface and means for removing distillate from that side of the condensing surface which is not exposed to atmospheric pressure.

4. A vacuum centrifugal still having a vaporizing surface and condensing surface, means for maintaining a vacuum between said surfaces, means for heating the vaporizing surface, means for cooling the condensing surface, means for introducing distilland onto the vaporizing surface, and means for removing condensate from the condensing surface said still being characterized by rotatable condensing and vaporizing surfaces which co-operate to form the walls of the casing of the still, which surfaces are exposed to substantially atmospheric pressure on one side, and during operation, to a vacuum on the other side and over which distillate and distilland respectively are caused to flow as a fllm by centrifugal force and further characterized by means for applying heat to the side of the vaporizing surface which is at atmospheric pressure.

KENNETH C. D. HICKMAN.

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