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0d- 1, 1946- v Q K. cu D. HICKMAN ' ‘2,403,639 VACUUM DISTILLATION PROCESS AND APPARATUS Filed June 20, 1944 ' ‘2 Sheets-Sheet 1 42' KENNETH C.D. HICIQVAN ‘ ' INVENTOR NW“ A 'ITORNE YS Oct- 1, 1946- ' K. c. ‘D. HICKMAN 2,408,539 VACUUM DISTILLATION PROCESS AND APPARATUS Filed June 20, 1944 74 _ _ I _ 2 Sheets-Sheet 2 FIG. 3. . . . . - . - - - . . . _, ..../ FIG.4. KENNETH C.D.HICMN 184 , v. _ INVENTOR 98 v BYWW ‘ COOLING FLUID _ (gnu-‘M ATTORNEYS Patented Oct. 1, 1946 2,408,639 vumrrrzp I STATES PATENT OFFICE vacuum msmm'non maas'rusmocnss m I Kenneth C. D. Hickman, Rochester, N. vit. assign I or to Distillation Products, Inc., N. Y., a corporation of Delaware Application June 20, 1944, ‘Serial No. 541,253 11 Claims. (clan-52) This invention relates to improved process and vapparatus for vacuum distillation of thermally decomposable substances while in the form of a thin film. ~ under conditions such that it can start to distill as soon‘as it reaches distillation temperature. In the following description I have given several 1 of the preferred embodiments of my invention but It is well known in the vacuum distillation art vit is to be understood that these are set forth for the purpose of illustration and not in limita to subject thermally decomposable substances to vacuum distillation while in the form of a thin tion thereof. film. The decomposable distilland is heated only for the short period of time required during ?ow ' In the accompanying drawings wherein like numbers refer to like parts, I have illustrated sev over the vaporizing surface in a thin ?lm. The 10 eral of the preferred embodiments of my inven undistilled residue can then belcooled and, if tion wherein: desired, the heat content thereof used to preheat I ‘ Fig. P1 is a vertical section of an improved grav the fresh distilland ?owing into the still. ‘One of the problems in the employment of such stills is ity ?ow'still embodying the features of my in bringing the distilland to distillation temperature 15 and rapidly cooling the‘ undistilled residue using ' some system of heat exchange. ’ from mainly in that an auxiliary external heater for economy and to diminish to a minimum the period of time in which the distilland is main tained at a high temperature. The problem in 20 centrifugal vacuum stills, and to a lesser extent in gravity ?ow thin film vacuum stills, is aggravated by structural limitations. Thus, in the centrif ugal vacuum stills it is inconvenient to heat or ‘ Consequently I a heat exchangers are placed outside'the casing. This means that hot liquid has to be piped for } , Fig. 2 is a vertical section of a gravity ?ow still similar to that illustrated in Fig. 1 differing there This is required - cool the distilland inside the still. vention; is used to heat the main portion of the vaporiz ing surface of the still; ' I ‘Fig. 3 is a vertical section of a centrifugal still provided with improved heat interchange in ac cordance with my invention: ' a Fig. 4 is a modi?ed centrifugal ‘vacuum still 25 'provided with a steep conical vaporizing surface, internal condensing surfaces and heat inter change and: ' ' . Fig. 5 is a section taken on line 5-5 of Fig. 4. relatively long distances and the hot pipes must Referring tovFig. 1, numeral I O‘designates a often pass through the relatively co'ld walls of the ?at, base plate integral with a cylinder I! casing. The ultimate exchange of heat is poor 30 whichrigid cylinder is closed at the top by a plate I‘. and thermal decomposition due to unavoidably Numeral l6 designates a cylinder serving as a still ~ long times of heating is increased. casing which is positioned on plate Ill so as to be This invention has for its object to avoid the substantially concentric with cylinder l2. Nu foregoing di?iculties. Another object of my in meral l8 indicates a gas-tight end plate integral vention is to provide improved vacuum distilla 35 with cylinder l6. Numeral 20 designates a gas tion process and apparatus whereby e?icient heat ket serving to form a gas-tight joint between plate interchange in a vacuum thin ?lm still is brought It andi?ange 22 of cylinder l8. Numeral 24 des about without substantial thermal decomposition. ignates a conduit connectedto evacuating pumps 7 A further object is to provide improved high-vac (not shown). Numeral 28 designates an annular uum unobstructed path distillation process and 40 collar mounted upon the inside wall of casing is. apparatus, particularly improved with respect to Numeral 28 designates a conduit connected to the heat losses and thermal ‘decomposition. Another gutter formed by collar Y26 and easing l6. Nu object is to improve the state of the art. Other meral I0 designates a conduit serving towith objects will appear hereinafter. draw liquid collecting on the upper part of base ' These and other objects are accomplished by 45 plate Ill. Numeral 32 indicates a conduit for in troducing liquid onto the top of plate i4. my invention which includes vacuum distillation Numeral 34 designates a coiled pipe which process and apparatus wherein a thermally de makes e?icient thermal contact with the upper in composable organic substance is subjected to dis t?lation under vacuum while in the form of a 50 side wall of cylinder II. This can be accomplished :by soldering or welding. Numeral 36 designates a thin film, heat is recovered from the residue and similar coil which is similarly mounted upon the the recovered heat is transferred to the incoming decomposable organic substance while it is dis lower inside wall of cylinder l2. ’ Numeral 38 des ignates a conduit which connects coil 36 with film. Theorganic substance is thus preheated 65 coil I4.» Numeral 40 designates a conduit‘which connects the top part of coil N to the intake of posed in the vacuum still in the form of a thin 2,408,639 3 . 4 circulating pump 42. Numeral 44 designates a conduit connecting the exhaust side of the pump 42 to the lower portion of coil 36. Referring to Fig. 2 numeral 50 designates a cen tral coil making eilicient thermal contact with the central inside wall of cylinder I2. The upper end of this coil connects to the lower end of coil turn is rigidly fastened to the lower portion of by a burner 58. Numeral 80 designates a conduit gutter I48. Numeral I50 designates a conduit for introducing distilland onto the inside upper wall cone I32 by ?ange I40 as illustrated. Plate I38 is provided with a number of holes I42 while the upper portion of cone I32 is provided with a number of perforations I44 to permit the egress of gases. Flange I40 is provided with a plurality of spacers so as to permit'liquid accumulating in side cone I32 to pass between the two elements 38 while the lower end of this coil connects to a of the flange and into gutter I46. Numeral I48 conduit 52 which leads to an external heating coil 54 surrounded by a furnace 56 and heated 10 designates a conduit for withdrawing liquid from which connects the upper portion'of coil 36 to the lower portion of external heating coil 54. Referring to Fig. 3, numerals 1'0 and 12 desig nate respectively a base plate and a drum-shaped cover which cooperate to form a gas-tight casing for a centrifugal vacuum still of well-known type. of cone I32. Numerals I52 and I54 designate heat-exchange coils upon the inside upper and lower walls of conical element I32 respectively. These 'coils are connected together and to cir culating pump 98 as previously described. Numerals I56, I58 and I60 designate superim Numeral 14 designates evacuating conduits lead posed cylindrical condensing surfaces positioned ing evacuating pumps (not shown). Numeral 18 designates an annular gutter integral with the 20 inside cone i52. These surfaces are stationary and are provided at the lower edge of each with upper portion of 12 to which is connected a with gutters I62, I64 and I68 respectively. These con drawal conduit 18. Numeral 80 designates a cir- ‘ densing surfaces are cooled by means of internal cular, shallow cone-shaped vaporizing surface ro cooling coils I68, I10, and I12 through which tatably mounted upon shaft 82 which is rigidly cooling ?uid is circulated by introduction held in the position shown by bearings 84. The through conduit I14 and withdrawal through shaft passes through the base plate ‘10 and is pro conduit i16. Condensate collecting in gutters vided with a gas-tight packed gland 86. Numeral 362, I64 and I66 is withdrawn respectively 88 designates an annular gutter into which the through conduits I18, I80 and I82. periphery of vaporizing plate 80 extends. Nu Numeral I84 designates a gear integral with meral 90 designates a withdrawal conduit con 30 the outwardly turned lip of plate I38. The gear nected to gutter B8. is driven by driving gear I86, which is in turn Numeral 92 designates a helical coil integral driven by shaft I88, which passes through packed with the central part of plate 80 and making effi gland I90. cient thermal contact therewith. Numeral 94 In operating the apparatus illustrated in Fig. designates a helical coil of larger diameter than 35 l, the still is evacuated by means‘ of pumps con coil 92 and integral with the outside portion, of nected to conduit 24. Liquid to be distilled is in plate 80. Numeral 96 designates a conduit con troduced through conduit 32. Heating element necting the inside end of coil 92 to the intake of comprising an electrical resistance wire II is put pump 98. Numeral 91 designates a reservoir or into operation and circulating pump 42 is started. expansion chamber for extra heat exchange liq Distilland collects on plate I4, flows over the up uid which is connected to the intake of pump 98 per edge of I2 and downward in a thin ?lm on by conduit 99 which gradually increases in dis the outside surface of I2. When this thin ?lm tance from shaft 82 as it passes from reservoir 91 reaches the area heated by heater II it is par to the intake of pump 98. Numeral I00 desig tially distilled. . The vapors thus formed con nates a conduit connecting the other end of coil dense on the inside wall of outer casing I6, flow 92 with the inside end of coil 94. Numeral I02 by gravity into gutter 26 and are withdrawn designates a conduit which connects the outside through conduit‘ 28. The hot undistilled residue end of coil 94 with the intake of pump 98. Nu on column I2 then flows in a thin film over the meral I04 designates a conduit for introducing distilland onto the center of vaporizing plate 80, 50 lower portion of column I2 opposite heat recov while numeral I06 indicates an electrical resist ance wire for heating the center portion of va porizing plate 80, the heat being re?ected toward plate 80 by re?ector I08. Numeral IIO designates a stationary gear rigidly mounted upon support H2 so as to engage with gear II4 which drives pump 98. Referring to Figs. 4 and 5 numeral I20 desig nates a rigid base plate upon which is mounted gas-tight conical still casing I22 which is pro vided with an evacuating conduit I24. Casing I22 is provided with a gas-tight cover or end plate I26 through which passes a stationary hol low shaft I28 which is rigidly mounted in the po sition shown by being integrally fastened to sup I port I30 and to base plate I20. Numeral I32 des ignates a cone of about the same shape as casing I22 but of smaller diameter which is rigid but ro ‘tatably mounted in the position shown by means of bearings I34 and I36. The innerhalf of bear ings I34 and I36 are‘mounted upon the wall of shaft I28 in a stationary manner. The outer half of bearing I34 is integral with the upper wall of ery coil 36. A heat transfer liquid such as di phenyl or “Dowtherm” in coil 36 is then heated to an elevated temperature. This hot liquid then flows upwardly through conduit 38 and preheat ing coil 34 due to the action of circulating pump 42. The distilland as it flows in a thin film over the upward portion of column I2 is thus pre heated while it is subjected to the vacuum dis tillation conditions. If the liquid should be pre heated to distillation temperature while still on the area of the preheater, it could distill and no unusual thermal decomposition, therefore, would take place. The cool heat transfer agent is then circulated downward through conduit 40 and cir culating pump 42 and is again passed through the heat-recovery coil 36. These operations are repeated throughout the distillation process. Undistilled residue accumulates on the upper sur face of I0 and is withdrawn through conduit 30. In operating the apparatus illustrated in Fig. 2, the still is put into operation the same as de scribed in Fig. 1. Burner 58 is put into operation. The heat-exchange fluid is then circulated by pump 42.‘ The ?uid ?rst passes through coil 36 rotating conical element I32 while the outer half of bearing I36 is integral with plate I38, which in 75 where it picks up heat from the undistilled resi 2,‘08,089 due on the lower outside wallof cylinder I2. This. partially heated ?uid then passes through con duit 80 into heater coil “where it is further heated. It then passes through conduit 52 into heater coil 50 where it heats the central portion of cylinder I2 to distillation temperature. The inside surface of I82 are condensed upon the cool outer surfaces of cylinders I88, I58, and I80. Three fractions are separated on these surfaces. These fractions ?ow by gravity respectively into conduits I82, I84, and I88, and are withdrawn respectively through withdrawal conduits I18, liquid is partially cooled by giving up some of its I80, and I82. heat content to the distilland and this partially My invention is of particular importance in cooled heat-exchange liquid then ?ows through connection with the preheating of thermally de coil 84 where it partially preheats the distilland 10 composable substances while in a thin ?lm and at the top of cylinder I2. The cool heat-exchange while under vacuum distillation conditions. The liquid then is returned through the cycle by cir similar treatment of the undistilled residue, 1. e., culating pump 42. while it is in the form of a thin ?lm and under In operating the apparatus illustrated in Fig. 3, vacuum conditions is important only where it is shaft 82 is caused to rotate by force applied out 15 to be further distilled to recoverthermally cle side of the still. Liquid to be distilled is intro composable substances. Obviously if all the de duced through conduit I04 onto the center of rotating plate 80. The system is evacuated through conduits 14 and the vaporizing surface 80 is heated to distillation temperature in the central portion thereof by heater I08. The dis tilland is caused to ?ow from the center to‘ the periphery of 80 in the form of a thin ?lm. Dur ing passage over the central portion it is heated to distillation temperature by heater I08. Va pors given oil’ are condensed on the upper wall, composable substances have been recovered there from or it is not to be further distilled it is not important to avoid thermal decomposition or to handle the undistilled residue carefully. Thereforé, it is to be understood that my inven tion is applicable in such cases only to the pre heating step and that the residue may be col» lected and heat regeneration accomplished in any manner so long as the regenerated heat is circu lated back to the incoming distilland while it is ?ow by gravity into gutter ‘I8, and are with in the form of a thin ?lm and under vacuum con drawn from the still through conduit 18. Un ditions. distilled residue is thrown from the periphery of What I claim is: 80 into gutter 88 and is withdrawn through con 30 1. High-vacuum distillation apparatus com~ duit 90. Coils 82 and 94, contain heat-exchange prising in combination a vaporizing surface, a liquid. During rotation pump 88 rotates with condensing surface, means for heating the va plate 80. Since gear H8 is stationary, gear H4 porizing surface, means for distributing distilland is caused to rotate and this actuates pump 88. onto the vaporizing surface in a thin ?lm, means Heat-exchange liquid is caused to ?ow by the 35 for removing undistilled residue from the va action of the pump 88 from coil 94 into coil 92 porizing surface, means for recovering heat from and thence by way of conduit I00 back into coil the undistilled residue while it remains in the 84. Heat is taken up from the undistilled residue form of a thin ?lm in the still, means for trans by coil 94 and is conveyed to coil 82 where the ferring this recovered heat to the incoming dis heat is given up to the distilland when it is ?rst 40 tilland while it is in the still, while it is in the introduced onto the vaporizing plate 80 in order form of a, thin ?lm and immediately previous to to preheat it, The distilland is thus preheated its passage onto the vaporizing surface, and while subjected to the vacuum and while it can distill as soon as it becomes preheated to distilla means for removing condensate from the con densing surface. tion temperature. There is, therefore, no lag 45 2. High-vacuum distillation apparatus com between preheating and distillation. prising in combination a vaporizing surface, a In operating the apparatus illustrated in Figs, condensing ‘surface, means for heating the va 4 and 5, the system is evacuated through con porizing surface, means for distributing distilland duit I24. Cone ‘I32 and integral pump 88 and onto the vaporizing surface in a thin ?lm, means heat-exchange coils I52 and I54, are rotated as 50 for removing undistilled residue from the vapor an integral unit by force applied through shaft I88, gear I88 and gear I84. Liquid to be dis tilled is introduced through conduit I58 onto the izing surface, means for recovering heat from the undistilled residue, means for transferring this recovered heat to the incoming distilland while inside upper surface I32. The liquid flows in a it is in the still, while it is in the form of a thin thin ?lm by a combination of gravitational and 65 ?lm while it is exposed to the high vacuum in centrifugal force to the bottom of cone I32, and the still and immediately previous to its passage is then thrown between the elements of ?ange onto the vaporizing surface in the form of a thin I40 into gutter I48, and is withdrawn as undis ?lm, and means for removing condensate from tilled residue through conduit I48. Gases pres the condensing surface. ent in the distillation chamber,.i. e., gases inside 60 3. High-vacuum unobstructed path distillation cone I32, pass through holes I 42 ‘at the base and apparatus comprising in combination a vaporiz perforations I44 at the top are then withdrawn ing surface, a condensing surface, separated from , the vaporizing surface by substantially unob Undistilled residue heats coil I54, as previously structed space, means for heating the vaporizing explained. This coil contains heat-exchange ?uid 65 surface, means for distributing distilland on the which then is forced by circulating pump 88 up vaporizing surface in a thin ?lm, means for re into preheating coil I 52, where the distilland is moving undistilled residue from the vaporizing preheated. The somewhat cool heat-exchange surface, means for recovering heat from the un ?uid is then returned by circulating pump 88 distilled residue while it remains in the form of to coil I54 as previously described. The central 70 a thin ?lm in the still, means for transferring portion of vaporizing surface I32 is heated by this recovered heat to the incoming distilland electrical coil I08 and re?ector I08 as described while it is in the form of a thin ?lm in the still, in connection with Fig. 3. and‘ immediately previous to its passage onto the Cooling ?uid is circulated through coils I68, vaporizing surface, and means for removing con I10 and I12. Therefore, vapors generated on the 75 densate from the condensing surface. through conduit I24. ' 2,408,689 8 surface. means constituting a continuation of the vaporizing surface for recovering heat from the undistilled residue while it is in the form of a ing surface, a condensing surface separated from thin ?lm and while it is exposed to the vacuum the vaporizing surface by substantially unob conditions prevailing in the still, means constitut structed space, means for heating the vaporizing GI ing a preheating portion of the vaporizing sur surface, means for distributing distilland onto face for transferring this recovered heat to the the vaporizing surface in a thin ?lm, means for incoming distilland while the distilland is spread removing undistilled residue from the vaporizing thereon in the form of a thin ?lm, and while it surface, means for recovering heat from the un-' is exposed to the vacuum conditions prevailing ii) distilled residue while it remains in the form of a in the still, and means for removing condensate thin ?lm in. the still, means for transferring re from the condensing surface. covered heat to a liquid, means for conveying this 8. The process of high-vacuum distillation heated liquid into thermal contact with the in comprising subjecting an organic substance coming distilland while it is in the form of a thin ?lm in the still and immediately previous to its 15 which tends to decompose at a temperature nec essary for distillation to high-vacuum distillation passage onto the vaporizing surface, and means while in the form of a thin ?lm, recovering heat for removing condensate from the condensing from the undistilled residue while it remains in surface. the still, while it is exposed to the vacuum there 5. High-vacuum unobstructed path distillation and while it is in the form of a thin ?lm, and apparatus comprising in combination a vaporiz 20 in, conveying the recovered heat to the incoming ing surface adapted to cause distilland to ?ow organic substance while it is in the form of a thin thereover in a thin ?lm by centrifugal force, a ?lm and while it is exposed to the vacuum condi condensing surface separated from the vaporizing tions prevailing duringthe vacuum distillation. surface by substantially unobstructed space, 9. The process of high-vacuum distillation 25 means for heating the vaporizing surface, means , comprising subjecting a thin ?lm of an organic for introducing distilland onto the vaporizing substance which tends to decompose at a tem surface, means for removing undistilled residue perature necessary for distillation to high-vacu 4. High-vacuum unobstructed path distillation apparatus comprising in combination a. vaporiz from the vaporizing surface, means for recover ing heat from the undistilled residue while it re um distillation by causing it to ?ow over a heated vaporizing surface in the form of a thin ?lm, re mains in the form ofa thin ?lm in the still and 30 covering heat from the undistilled residue as it for transferring it to a liquid, means for adding ?ows in a thin ?lm over the last part of the va additional heat to this partially heated liquid, means for circulating this heated liquid into thermal contact with the vaporizing surface and then into thermal contact with incoming dis porizing surface and conveying the recovered heat to the incoming organic substance while it tilland while it is in the form of a thin ?lm in 10. The process of high-vacuum distillation comprising subjecting a thin ?lm of an organic the still and immediately previous to its passage onto the vaporizing surface, and means for re moving condensate from the condensing surface. is in the form of a thin ?lm on the ?rst part of the vaporizing surface. _ - substance which tends to decompose at a tem perature necessary for distillation to high-vacu 40 6. High-vacuum unobstructed path distillation um distillation by causing it to ‘?ow over a heated apparatus comprising in combination a vaporiz ing surface adapted to cause distilland to ?ow thereover in a thin ?lm by centrifugal force, a condensing surface separated from the vaporizing surface by substantially unobstructed space, means for introducing distilland onto the vapor izing surface, means for removing undistilled residue from the vaporizing surface, means for recovering heat from the undistilled residue while it remains in the form of a thin ?lm 0n the out ermost part of the centrifugal vaporizing surface, vaporizing surface in the form of a thin ?lm, recovering heat from the undistilled residue, con veying the recovered heat to the incoming or ganic substance while it is in the form of a thin ?lm within the still and while it is exposed to the high vacuum in the still and then immediately heating this preheated thin ?lm to distillation temperature. 11. The process of high-vacuum distillation comprising subjecting an organic substance which tends to decompose at a temperature necessary means for transferring this recovered heat to the for distillation to high-vacuum distillation by incoming distilland while it is in the form of a causing it to ?ow in the form of a thin ?lm by thin ?lm on the innermost part of the centrifugal centrifugal force over a heated vaporizing sur 55 vaporizing surface, and means for removing con face, recovering heat from the undistilled residue densate from the condensing surface. at the outermost portion of the vaporizing sur 7. High-vacuum unobstructed path distillation face and while the undistilled residue from which apparatus comprising in combination a vaporiz the heat is recovered is still in the form of a thin ing surface, a condensing surface separated from and conveying this recovered heat to the the vaporizing surface by substantially unob 60 ?lm, innermost portion of the centrifugal surface upon structed space, means for heating the vaporizing which the incoming distilland is disposed in the surface, means for distributing distilland onto the vaporizing surface in a thin ?lm, means for removing undistilled residue from the vaporizing form of a thin ?lm by centrifugal force. KENNETH C. D. HICKMAN.