US2202007A

US2202007A - Distillation of fatty acids

Info

Publication number: US2202007A
Application number: US84626A
Authority: US
Inventors: Ittner Martin Hill
Original assignee: Colgate Palmolive Co
Current assignee: Colgate Palmolive Co
Priority date: 1936-06-11
Filing date: 1936-06-11
Publication date: 1940-05-28
Anticipated expiration: 1957-05-28
Also published as: DE738710C; US2202008A

Description

y 8, 194.0. M. H. ITTNER 2,202,007

DISTILLATION 0F FATTY ACIDS Filed-June 11, 1 956 a Sheets-Sheet 1 TO VACUUM ZNVENTOR BY M v dwnwq ATTORNEYS May 28, 1940, M. H; ITTNER 2,202,007

' DISTILLATION 0F FATTY ACIDS F iled June 11, 1936 s Sheets-Sheet 2 TO VACUUM 7/ INVENTOR uzq" W M BY 22.2% flaw/M ATTORNEYS May 28, 1940. M. H. ITTNER DISTILLATION OF FATTY ACIDS Filed June 11; 1936 3 Sheets-Sheet 5 INVNTOR BY 1 Mi -41 ATTQRNEYS mw W I! h, 255 v NW hm MW .ww MEJJFQQ Patented Ma 28, 1940 UNITED STATES PATENT OFFICE 2,202,007 DlSTlLLATION F FATTY Aoms Martin Hill Ittner, Jersey City, N. J., assignor to Colgate-Palmolive-Peet Company, Jersey City, N. J., a corporation of Delaware Application June 11, 1936, Serial No. 84,626

Claims.

a radically smaller heat consumption than has heretofore been possible, while at the same time the quality of the fattyacids distilled is improved, and the losses in distillation, due to the formation of tars and to decomposition, are substantially lessened.

The process of the present invention, while adapted for, and useful for, the distillation of high boiling liquids generally, particularly such high boiling liquids as are not miscible with water and are advantageously distilled by a vacuumsteam process, such as high boiling petroleum fractions, is particularly adapted for, and particularly designed for, the distillation of fatty acids.

The term fatty acids, as used herein, and as commonly used in industry, includes not only the true fatty acids, which are saturated, but also the related unsaturated acids with varying degrees of unsaturation. These fatty acids are commonly obtained by the saponification of natural fats and oils; which consist of triglycerides of the fatty acids, and are generally obtained as mixtures of various saturated fatty acids and various unsaturated fatty acids. In general, the saturated fatty acids are more stable than the unsaturated fatty acids, and are more resistant to decomposition by heat and to oxidation.

The improved process of the present invention makes it possible to distill fatty acids with a radically loweredheat consumption because it permits the recovery of the heat from condensation of the fatty acid vapors as well as sensible heat of the fatty acid vapors and the hot condensed fatty acids, and, where jet steam is used to aid in the distillation, much of the sensible heat of the water vapor, and the utilization of such heat for preheating the fatty acids'and producing the jet steam used in the distillation, and also increases the economy of the operation by decreasing the losses due to decomposition and tar formation. This process permits the use of much higher vacua, or lower absolute pressures, within the still and in the vapor space over the liquid being distilled and thereby reduces the amount of jet steam required to aid in the distillation and also lowers the temperature at which the distillation may be carried out in a' commercial manner.

Apparatus as a whole advantageously adapted for use in carrying out the process includes a heating zone, in which the fatty acids being distilled are heated and in which the volatilization takes place, a vapor space above the heating zone, a separator, in which the vapors are separated from entrained material and a suitable cooling zone, in which the fatty acid vapors are condensed and the accompanying water vapors cooled, all

within a single air-tight shell similar to the shells of stills now commonly provided. The apparatus is also provided with suitable means for supplying heat to the material being distilled, such as high pressure steam coils, and with ejector jets for mixing the contents of the still with superheated steam if desired, the jets being so located as to insure effective and uniform heating of the still contents by the heating coils; suitable insulating means for preventing the passage of heat from the separating zone, through which the vapors pass directly from the vapor space above thestill contents, to the cooling zone, or zones, which is or are annular and surrounding the separator, the insulating device advantageously defining the separator; and a suitable connection to a vacuum device to permit the flow of water vapor from the still and to insure the maintenance of a low pressure in the still.

The improved process of the invention in its so that the heat from condensation of the fatty acids, and a large part of the sensible heat of the fatty acid vapors and the hot condensed fatty acids and a large part of the sensible heat of the water vapor is used to preheat the fatty acids fed to the still, and to generate and superheat the superheated steam used as jet steam in the still. Thus by the process of the present invention, a very large part of the available heat of the vapors is recovered and used, and the only heat which it is necessary for the high pressure steam to supply is the latent heat of vaporization of the fatty acids, and the heat lost by radiation from the heating zone of the still.

In the apparatus, all passages through which the vapors must pass, that is, the vapor space above the still contents, the separator, and the cooling zone or zones are of such substantial size that very little resistance to flow of the vapors is offered, and the pressure difference between different parts of the still is very slight, a pressure difference as small as a fraction of a millimeter of mercury between the vapor space just above the still contents and the vacuum device outside of the still used to maintain the vacuum within the still being easily obtainable. Because of this small pressure drop, the apparatus may be operated, and the process carried out, while pressures as low as three millimeters of mercury are maintained within the still while using open jet steam. The low pressure which may be maintained within the still is distinctly advantageous, as it greatly decreases the temperature at which effective and rapid distillation of the fatty acids can take place, and thus reduces to a substantial extent the decomposition and tar formation which ordinarily occurs.

The invention will be further illustrated and explained in connection with the accompanying drawings, which show, in a diagrammatic fashion,

apparatus which is adapted for carrying out the process of the invention, but the invention is not limited thereto.

In the drawings:

Fig. 1 is a vertical section, with parts in elevation, of a suitable still;

Fig. 2 is an elevation showing a suitable arrangement of the various parts of the apparatus;

Fig. 3 is an enlarged section of a suitable device for drawing fatty acids from the still;

Fig. 4 is a vertical section of a portion of a still, showing a modified arrangement of the cooling zones; and

Fig. 5 is a horizontal section Fig. 4.

In Fig. 1 the still I is shown. as provided with an outer shell 2, with a lining 3" of a suitable corrosion-resistant metal, such as stainless steel, attached thereto. The shell is advantageously made in three sections, 2a, 2b, and 2c, bolted together by flanges 4. The interior of the still is divided into several zones or sections in which the operations of the process take place. At the bottom of the still are provided coils 5 which may I be provided with high pressure steam, or other suitable heating medium, to provide the heat necessary for the volatilization of the fatty acids.

The level of the liquid being distilled is normally maintained somewhat above the heating coils. Above the heating coils, and above the liquid, is a vapor space 6 leading directly into the separating zone 1, which is of large diameter and is provided with the helical or spiral fins 8. The vapor space and the separator are defined by the double-walled partition 9 which is advantageously made of relatively thin metal and with polished surfaces. Small holes l0 are provided in the outer sheet of this insulating partition to provide communication between the still and the interior of the partition so that the same pressure exists within the partition as exists within the still proper, these holes communicating with a relatively cool portion of the still, sothat no condensible vapors, which might condense between the walls of the partition, and impair its insulating efficiency, can enter through them into the space between the walls and condense. This partition rests upon the lipped ledge II, which provides a small ledge in which liquid fatty acids collect and form a liquid seal to prevent the transfer of vapors between the still wall and the insulating partition. A few small holes i 2 may be provided at the bottom of the inner wall of this partition to permit the drainage of any maof the still or terial which may get within the partition. The level of the liquid being distilled is normally maintained a little above the ledge ii. A gauge glass i3 is provided to determine the level of the liquid.

The insulating partition defines the separating zone, which is of a diameter approximately onehalf the diameter of the shell, and below the separating zone flares out to the diameter a little less than that of the shell, as shown at l4, forming the vapor space above the liquid, and providing a throat leading the vapors into the separating zone, thus serving not only to insulate the sides of the separating zone, but also to insulate the vapor space and prevent or minimize losses of heat through the sides of the still adjacent to the vapor space. Above and surrounding the upper portion of this insulating partition is a bell-shaped partition l5 which is double-walled, and which serves to deflect the vapors which pass upwardly through the separating zone down past the series of coils I6, I! and I8, which constitute the primary cooling agencies, where the vapors are cooled and a large proportion of the fatty acids condensed. This bell-shaped deflector is supported on brackets i9, and the vapors after passing down between this bell and the insulating partition pass up between the bell and the wall of the still, past the coils 20 and 2| and then pass out through the pipe 22 to a suitable vacuum device.

The deflector bell is advantageously doublewalled, and is made of a suitable corrosion-resistgutters 24 at the top, and the upper section consisting of an inner and an outer dome 25, which rest in the gutters and are held in place by bolts 26. Suitable holes are provided in the bell-deflector for the passage of various tubes leading to the coils which are placed between the insulating partition and the bell-deflector.

Three sets of coils I6, I1 and I8 are provided between the partition and the bell-deflector. Of these, the upper section 16, with an inlet 21 is used forsuper-heating the steam. The steam passes through this coil where it is superheated and then passes down the inner pipe 28 of the double pipe 29 provided in the center of the coil and passes out of this pipe through the jets 30, which are preferably arranged so that the discharging steam and the fatty acids which are intimately admixed with it in the jets have a horizontal path, and are forced into intimate contact with the heating pipes 5 thus insuring the uniform and effective heating of the liquid, and its intimate admixture with the superheated jet steam.

The second set of coils l1 leads from the manifold 3| into which the fatty acids to be distilled are introduced through inlet 32 to the manifold 33, and thence to the outer pipe of the double pipe 29 which runs down the center of the still and discharges the heated fatty acids into the liquid at the bottom of the stillsomewhat below the upper surface.

The third set of coils I8 leads from the manifold 34 to the manifold 35 and these coils are used to vaporize the water and form the steam which is subsequently superheated and used as jet steam in the distillation, water being introduced through inlet 36, and hot water and steam being taken from outlet 31. The vapors thus pass over the three sets of coils in series, superheating the steam, preheating the fatty acids, and producing the, steam which is used in the distillation. These coils are-so arranged that any fatty acids which may be deposited upon them by of the still down into the trough. Between the bell-deflector and the outer wall or shell of the still there are provided cooling coils 20 and 2H, through which cold water or other cooling agent may be circulated to further cool the vapors after they have been partially cooled by 'the other coils, and thus to condense the last traces of fatty acid and to insure that the vapors which pass out of the still are substantially free from fatty acids. In the apparatus illustrated, two such cooling coils are provided; but one cooling coil may .be used if desired, or more than two cooling coils may be used.

An outlet 4| is provided at the side of the still from the trough for the removal of the fatty various sizes, and with wide variations in the proportions of the various zones and parts of the apparatus. 2400 pounds of fatty acids per hour, a still having an-outer shell about 8 feet in diameter may be provided, which may be about 15 feet high. The separating zone, which should be quite large. may be about 4 feet in diameter and about 6 feet high, the vapor space beneath the separator may be about 3 feet high, with the heating zone where the liquid fatty acids are heated being about 3 feet deep. The deflector-bell may be about '7 feet in diameter and about 7 feet high. A still of such dimensions provides adequately large vapor spaces or passages which offer no substantial resistance to the vapor flow. The cooling coils, and the heating coils, may be made of 2 inch tubing, ofa suitable corrosion-resistant metal.

Fig. 2 is a diagrammatic sketch of the exterior of the still, showing the general arrangement of the exterior parts. shown at I with the heating coils connected, by pipes 43a provided with valves 43b, to a suitable manifold 43 connected to a high pressure steam supply to supply the steam required for heating,

I brought into pipe 45 from an outside source, the

flow being controlled by the needle valve 41. Distilled water is preferably used. The water flows through the tube 46 and connection 36 and mamfold 34 into the coils, where a part of it becomes For a still designed to distill about In this figure, the still is.

converted into steam by the heat absorbed from the fatty acid vapors which flow over the coils and the heated cooling water and the steam generated rise through the coil and flow out through the connection 31 and tube. 48. Most of the water returns to tube 46 through connection 50, while the steam and the rest of the water go into separator 49, in which the water may return to tube 46 through connection 5!. The level of thewater in the separator is maintained a little below tube 48 at the level of outlet 54, and is indicated by the gauge glass 52.

A suitable connection 53 is provided at the top of the separator for supplying steam'from an outside source when starting operation, and with a suitable pressure relief valve 54 for the discharge of excess steam and water. Another pressure relief valve 55 may be provided at the top of the separator. A pressure gauge '56 may be provided at the top of the separator to show the pressure maintained within the chamber. The chamber is preferably maintained at a superatmospheric pressure, e. g., 5 pounds gauge or less, to avoid the possibility of air leaking into the, separator and into the still. At the top of the separator is provided an outlet 51 for the separated steam which is connected to tube 58 which leads through connection 2'! to the superheater coil by the parallel tubes 59, each provided with a valve 60, and with an orifice Bl which may be of the same size or of different sizes, and which enable the flow of steam from the separator to the superheater coil to be adjusted to a predetermined, desired amount.

The cooling coils 2B and 2!, between the belldeflector and the outer wall of the still may be supplied with cold water through

inlets

62 and 63 and may discharge through

outlets

64 and 65, the cold water thus flowing concurrently with the outgoing vapors, or the direction may be reversed.

In Fig. 3 is illustrated a suitable connection for the removal of liquid condensed fatty acid from the trough 38. (Fig. 1). As illustrated, a bushing 66 is welded into the lower part of the dam 39 of the trough, and a special nipple 61 is provided to be screwed into this bushing. A flanged nipple 68 with an inner diameter somewhat greater than the outer diameter of nipple .57 iswelded to the shell, so that the nipple 61 when connected to the bushing 66 is centrally located within the flanged nipple 68. Radially slotted bolt holes are provided around the flange of the nipple 6B. The nipple 61 is threaded on each end with standard pipethreads' and along a portion of its outer surface with machine threads having the same pitch as the pipe threads but having a larger outer diameter. A small recess is provided in the face of the flanged nipple 68 for a gasket 59. A smooth-faced flange l0 provided-with radial slots corresponding to those in nipple 68 is provided with an inner hole threaded to match the machine threads on the nipple 61. Nipple 61 is then screwed into bushing 66 and the flange screwed down until it presses upon the gasket. The flanges are then bolted together with bolts H and tightened so as to make a tight joint between them. A follower 12 is also screwed upon the outer part of nipple 51 with a grommet 13 between it and the that air does not leak into the still at these points.

In Figs. 4 and 5 there is illustrated the upper part of a still showing a modified arrangement of the cooling zone, with a modified vapor passage, which may be used. In the modification of the apparatus illustrated in these figures, there is provided a separating zone 14, defined by an insulating partition 15 of the same construction as that shown in Fig. 1, within which are the helical or spiral vanes 16, two in number, which serve to remove entrained matter from the vapors. In this modification, no deflector-bell is used, the vapors passing from the top of the separating zone and being deflected by the top of the still. Three sets of cooling coils, l1, l8 and 19, are provided in the zone between the insulating partition and the wall of the still, the vapors after being deflected from the top of the still passing over these coils. These coils are used for much the same purposes as those provided in the apparatus described in Fig. 1, the upper coil being used to superheat jet steam, the central coil to preheat fatty acids, and the lower coil to generate steam. There are also provided two

helical baffles

80 and 80a having about the same pitch as the cooling coils and each extending a little more than one-half of the Way around the insulating partition 15, which deflect the vapors so that instead of flowing downwardly over the cooling coils, they flow downwardly and around the insulating partition in a helical or spiral path,

finally passing out of the still through the opening 8| to the vacuum devices.

In the arrangement shown in Figs. 4 and 5, care should be taken that the cooling coils have an adequatearea to cool the vapors to an extent sufficient in insure that-substantially all of the fatty acids are condensed within the still, so that no substantial amount passes on to the vacuum devices. The fatty acids condense on the cooling coils, and drop down into a collecting trough, which is of the same construction as shown in Fig. 1.

In the arrangement shown in these figures, instead of a single superheating coil being used, a plurality of coils is provided, the saturated steam entering through inlet ,82, into manifold 83 passing through the coils H to be superheated and into manifold 84 and then into the inner pipe 85 of double pipe 86 and to the jets. The fatty acids enter the coils 18 through inlet 88 and manifold 89, and pass spirally upward through the coils into manifold 90 and.then pass into the outer pipe of the central double pipe. Cooling water is supplied through inlet 9| to manifold 92 from where it passes spirally upward throughcoils 19 into manifold 93 and then passes into a separator such as described in connection with Fig. 2 through outlet 94.

In the apparatus illustrated in Fig. 1, no insulation is provided on the still. It will be understood that insulation is provided at the lower part of the still, that is, around the portion of the still where the liquid material is maintained and somewhat up the sides of the still at the vapor space. It is not necessary to provide much insulation at the level of the vapor space, as the insulating partition effectively serves to insulate this portion of the still and to prevent any substantial loss of heat by radiation. 'Above the vapor space, no exterior insulation need be provided, and in fact, such insulation is generally undesirable. At this portion of the still, it is desirable to cool the vapors, and provision is even made for the introduction of cold water to provide for the complete cooling of the vapors. The walls of the still above the vapor space normally are quite cool, and, in any case, any heat which might be lost by radiation from these portions of the still does not rob heat from the heating zone, and does not lessen the thermal efiiciency of the still but may add to its condensing efficiency.

In operating the still illustrated in Fig. 1, a body of liquid fatty acids is maintained in the bottom of the still at a level somewhat above the top of the heating coils, and is heated by the high pressure steam in the coils. A high vacuum is produced in the still by a suitable vacuum device (not shown). superheated jet steam is introduced through the jets into the liquid material, insuring the intimate contact of the liquid material with the heating coils and insuring the effective and uniform heating of'the material. The vapors of the fatty acids, admixed with the water vapor, pass up from the liquid material into the vapor space 6 and then through the throat into the separating zone i. Here the vapors are deflected by the helical vanes 8. The attenuated fatty acid vapors and water vapor are defiected readily by the vanes, and no substantial resistance to the flow of these vapors through the separating zone is offered. Any entrained liquid or non-voiatilized material which is carried along with the vapors through the vapor space into the separating zone, being many times heavier than the vapors, is not diverted from its path and comes into contact either with the vanes of the separator or the insulating partition and flows down and drips back into the liquid in the bottom of the still. Any material which is so deposited on the vanes will flow downward along the line of greatest slope, which is toward the center and down the center of the vanes. This separator may be provided with any suitable number of vanes, four vanes being suitable, as the size of the passageway for the vapors is so great that no substantial resistance to their flow is offered. The vapors after passing up through the separating zone are deflected by the bell-deflector i5 and pass down over the three sets of coils between this bell and the insulating partition 9. In the lower set of coils, cooling water enters through tube 36 into the manifold 34 and passes upwardly through the spiral coils into the upper manifold 35, a large part of the water being converted into saturated steam, and the admixed water and steam being separated by connection 50 and separator 49, the water being returned to the coils and part of the steam being passed through one or the other, or both, of the orifices 6| in controlled amounts, and then passing through the upper coil IS in which it is superheated. The saturated steam to be superheated thus comes into indirect contact with the hottest fatty acid vapors coming from the separating zone and is superheated to a temperature approximating the temperature of the liquid material in the still. The steam after being superheated passes from the coil downwardly through the inner pipe of the double pipe and is conducted by suitable connections to a plurality of steam jets in the lower part of the still where it is discharged as jet steam to assist in the distillation.

The bell-deflector l5 serves not only to deflect the vapors downwardly and over the cooling coils but also serves to prevent loss of heat from the vapors into the space abovethe bell-deflector and close to the top of the still. The vapors in this upper space are cool, and any heat supplied to them from the hot vapors from the separating zone would, of course, be wasted and lessen the efliciency of the condensation in the space between the bell-deflector and the outer still shell. -The double-walled deflector-bell, which is advantageously made of polished metal, and which is highly evacuated, being indirect communication with the still, serves effectively as an insulating agent to prevent the transfer of heat from the hot vapors to the cooler vapors above, so that the vapors which come into contact with the superheater coils, and with the preheating coils, are substantially at the temperature of the liquid contents of the still.

The fatty acids which are fed to the still are preheated, in the second set of coils it by the fatty acid vapors and the water vapor that accompanies them. The fatty acids, preferably dry, are introduced into the coils it by the .tube

32 connecting with manifold 36 which distributes the fatty acids through the coils whence they pass spirally upward and discharge into the manifold 33. The fatty acids are thus preheated by heat exchange with countercurrent flow of the the temperature or the fatty acid vapors to any substantial degree. The preheated fatty acids,

substantially at the temperature of the still con tents,'are led down between the inner pipe and 'the outer pipe of the double pipe to a point below the level of the liquid in the heating zone and near its center. The amount of feed is regulated by the rate of distillation and is such as to maintain the liquid level in thestill at its most eifective point, the gauge glass indicating this level.

The heat exchange-coils which condense fatty acids and cool the liquid condensed fatty acids and cool the fatty acid vapors and the water vapor and generate and superheat thesteam used as jet steam and preheat the fatty acids fed to the still are so placed that none of the fatty acids which may condense on their surfaces may drop into the separating zone and thence into the bottom of the still but all must run downward betweenthe insulating partition and the bell and be collected in the trough. If desired, instead of collecting all of the condensed material in a single collector, separate collectors may be placed at various locations within this cooling zone to permit fractionation or fractional condensation of the hot vapors. For example, if fractional condensation of hot fatty acid vapors is desired, or if the still is used for the dis tillation of high boiling petroleum fractions where fractional condensation is desired, the still may be provided with a series of collectors along the coolingzone, so that as the vapors become progressively cooled, and as the condensate becomes more and more volatile, the more volatile constituents may be separated from the less volatile constituents.

The preheating which takes place' After the vapors have passed down between the space between the insulating partition and the bell-deflector, they pass upwardly between the bell-deflector and the wall of the still, the supplementary cooling coils 20 and 2| being provided here to insure the complete condensation of fatty acid vapors before removing the water vapor from the still through the upper outlet which leads to the vacuum device.

Thus the fatty acids condense within the cooling zone with substantial completeness and run down into the collecting trough 38 from which they are removed through the outlet M, which may be constructed as described above, by a pump or drop-leg or other suitable means.

The amount of heat which is available for accomplishing the preheating operation, when the still is properly constructed and the process is properly carried out, is considerably in excess of that required. Thus in condensing the fatty acid vapors and in cooling the resulting liquid fatty acids and cooling the water vapor considerably more heat is given off than is necessary to generate and superheat the open jet steam employed and to preheat the fatty acid feed. This excess .heat is absorbed in part by the supplementary cooling coils located between the bell-deflector and the wall of the still and is partly radiated from the outer part of the shell. Advantage is taken of the fact that there is excess heat available in the construction of the still, and in its operation. In the preheating operation, about vide each set of coils with a reasonable excess of surface over and above that required to enable the transmission to the material being heated in the coils the amount of heat required to accomplish the heating operation for which the coil is designed. The excess of coil surface provided in each set of coils cannot operate to cause one set of coils to absorb more heat than to superheat the steam to about theistill temperaturecan be absorbed. Similarly, in the coils provided for the preheating of the fatty acid feed, only sumcient heat can be absorbed to heat the fatty acids to about still temperature, and, as the coils used for the generation of steam are preferably located for absorbing heat after the vapors have passed the superheating and proheating coils, any heat absorbed by these steamgenerating coils cannot deprive the others of heat. These last coils absorb more heat, and thus generate more steam than is necessary for the supply of superheated jet steam to the still, and this excess steam can of course be used for other purposes. Similarly, the area of the surface of the cooling coils provided between the bell-deflector and the outer shell of the still does not have to be carefully proportioned, as it is merely necessary to insure that these coils sufliciently cool the outgoing vapors to insure the condensation of'all of the fatty acids.

The outletpipe through which the water vapor is conducted after the fatty acid vapors have been condensed and which leads to the vacuum devices does not have to be as large as the other vapor passages in the still, as the vapor which passes through this pipe has avolume which is much less than the volume of the vapors which pass, for example, through the separating zone. In the separating zone, and at the upper portions of the primary cooling zone, the vapors consist of a mixture of fatty acid vapors and water vapor, and if, as in a typical case, the amount of superheated jet steam used is about 10% of the Weight of the fatty acids distilled,

the ratio of the volumes of water vapor and fatty acid vapors is about 3 to 2. Thus when the fatty acid vapors are removed, the volume of the vapors which must flow through the apparatus is reduced by about two-fifths, and with the concomitant cooling of the water vapor, the volume is still more reduced, so that the volume of vapor which passes through the outlet is much less than that which passes through the separating zone.

In carrying out the process as described, and in apparatus as described, I find that it is possible to carry nut the distillation with pressures in the still ranging from 3 mm. to 6 mm. of mercury, or even less. These low pressures within the still are made possible because the resistance to flow of the vapors oifered in the various parts of the apparatus is extremely small, large passageways being provided for the vapors, so that the difi'erence in pressure between the vapor space, for example, in the still and the portion of the outlet pipe adjacent to the-vacuum devices may be as small as a fraction of a millimeter. Thus with a vacuum device capable of reducing the pressure in the outlet pipe to about 3 mm. of mercury, the amount of pressure required to force the vapors from the vapor space through the various parts of the apparatus and up to the vacuum devices may be as small as a fraction of a millimeter, with the result that the distillation itself is carried out within the apparatus and at a pressure of 4 mm. of mercury or less. This lowered pressure which is maintained within the still enables the use of considerably lower temperatures in the distillation, with consequent decrease in the de-' composition of the fatty acids, particularly the unsaturated fatty acids which are always present in commercial fatty acids, and increases the yield of distilled acids and improves the quality of the distilled acids.

v The only source of outside or external heat which need be used in carrying out the process and in operating the apparatus is the high pressure steam supplied to the heating coils at the bottom of the still. The amount of heat which is required to be supplied by these heating coils is radically less than the amount of heat required to be supplied tocarry out a similar distilling operation in such stills as have heretofore been provided, being about 30% of the heat heretofore.

required, or even less. The only heat required to be supplied is the heat to vaporize the fatty acids at about the temperature at which they are vaporized, in other words, the latent heat of vaporization of the fatty acids, and the small amount of heat which is lost by radiation from the lower portion of the still, that is, the portion of the still below the vapor space. This radiation loss is only about one-fourth, or possibly a little less. than one-fourth, of the radiation loss ordinarily encountered in stills of similar capacity.

In similar distillation operations as heretofore carried out, it has been necessary to preheat the fatty acids and to generate the steam and superheat the steam by outside sources of heat; the heat content of the vapors has never been made available for these purposes before. The amount of heat which has heretofore been required for preheating and for generating steam and superheating it has been about twice the amount of heat required to supply the latent heat of vaporization of the fatty acids or somewhat more, and as the radiation losses from such stills as have heretofore been provided have been about four times the radiation loss from the still of the present invention, it is apparent that in carrying out the process of the present invention, the amount of heat which must be supplied to carry out the distillation is about one-third, or less, of the amount of heat which has heretofore been required. This substantial saving in the amount of heat required, coupled with the greater yield and improved quality of the distilled acids are advantages which flow from the present invention.

As an illustration of the heat economy which can be obtained by the present invention, the following comparison of the heat consumption of a still operated in accordance with the present invention, and a still constructed and operated in accordance with common practice, is given. This heat balance is based upon the assumption that both stills are operating on the same material and are distilling it at equal rates, and the further assumptions that the stills are operated at such a rate that 2400 pounds of distillate per hour, from a feed containing 99% free fatty acids, are obtained; that the average still temperature is 428 F.; that the specific heat of the feed and fatty acids is 0.6; that the latent heat of vaporization of the fatty acids is B. t. u. per pound; that thefatty acids are fed to the stills at 200 F.; that the distillate leaves the still at F.; that the water supplied is at 122 F.; and that the superheated jet steam used is 240 pounds per 1 hour, or 10% of the weight of the fatty acids distilled. It is also assumed that the still constructed and operated according to common practice is insulated in accordance with accepted practice over its entire surface, over the gooseneck, and over the separator, and that the still operated in accordance with the present invention is insulated over the-bottom and up the sides to a point slightly over the level of liquid within the still. All of the assumptions made above are well within the range of actual practice, and any variations in these assumptions will effect the results but slightly provided theassumptions are properly applied to both types of stills alike, with the actual advantages of operating according to the present invention being taken into account.

Based upon these assumptions, the following table shows the heat required for the operation of a still constructed and operated as in common The following table shows the amount of heat required for operating a still adapted for use in carrying out the process of this invention and operating in accordance with the present invention and distilling atthe same rate for a period of one hour.

It will be noted that in the second table, no heat input is required for generating the steam or for superheating it or for preheating the feed, because, as pointed out above, there is more heat available from the vapors than is required for these purposes. It might be'pointed out that the amount of steam required to carry out the distillation is somewhat less when the improved process and apparatus of the present invention are used than has heretofore been required, and that less jet steam can be used with equally eflicient distillation, largely because of the fact that the apparatus offers almost no resistance to flow of the vapors and allows the use of a smaller pressure differential between the vapor space and the vacuum device, and a higher vacuum within the still. However, this decreased amount of steam which may be used in carrying out the process would not affect the heat balance givenabove, as there is more than enough heat avail able to generate and superheat 10% of steam based upon the weight of the fatty acids, or even more. In any event, less'jet steam is required when operating in accordance with the present invention and the still may be operated with less jet steam than other types of stills, while giving equivalent performance. The resulting lesser amount of'water vapor produces an important economy and improvement in vacuum in the operation of the vacuum device.

Where desired, the cooling space provided may be separated into variouszones for the fractional condensation of the hot vapors, thus permitting the fractionation of the distillate. Also, the invention in its broader aspects is advantageous for the dry distillation of fattyacids.

Where the invention is used for the dry distillation of fatty acids, and no. supply of superheated jet steam is required, the heat given up by the hot vapors in the cooling zone may be used to preheat the feed, and also may be used to supply steam toother apparatus, or may be used for heating other liquids as desired. Nevertheless, the invention is particularly applicable to the vacuum-steam distillation of fatty acids. For example, in the distillation of fatty acids from cocoanut oil, the use of jet steam enables the distillation to be carried out at a temperature as much as 25 F. or more, lower than the temperature required if the jet steam is not used, and simple dry distillation is used, and the drop in the temperature when distilling fatty acids derived from 'tallow is even greater. Furthermore, the steam aids in bringing about intimate contact of the liquid being distilled with the heating coils and insures the intimate and effective contact of the liquid with the heating coils, thus greatly increasing the rapidity of the distillation.

I do not in this application claim the new apparatus described, as this is claimed in my divisional application Serial No. 145,126, filed May 27, 1937.

I claim:

1. The process of distilling fatty acids from a body of liquid undergoing distillation in the lower portion of a still provided with indirect heating means to supply the latent heat of vaporization which comprises vaporizing such fatty acids with the aid of indirect heat and a high vacuum, separating entrained unvolatilized material from the resulting hot vapors without substantially reducing their temperature,- and preheating the' fatty acid feed to substantially" the temperature of the still by subsequent indirect generally countercurrent contact with the hot vapors freed from entrained and unvolatilized material, the hot vapors being brought from said body of liquid in the lower portion of the still into such contact with the feed before undergoing any substantial reduction in temperature below the temperature. of said body of boiling liquid.

2. The process of distilling fatty acids from a body of liquid undergoing distillation which comprises vaporizing such fatty acids with the aid of heat, direct steam and a high vacuum, separating entrained unvolatilized material from the resulting hot vapors without substantially reducing their temperature, and subsequently passing the hot vapors over cooling means in indirect heat exchange relationship therewith for condensation of fatty acid vapors, and to'generate said direct steam from water supplied to a portion of said cooling means and to heat the fatty acid feed and generated direct steam separately with heat recovered from said hot vapors to substantially the temperature of the still, the hot vapors being brought into contact with said cooling means before undergoing any substantial reduction in temperature, and contacting said.

heated direct steam and said heated fatty acid feed within said body of liquid undergoing distillation for the volatilization of fatty acids.

3. The process of claim 2, in which the hot vapors, after the removal of entrained material, are brought successively into indirect generally countercurrent contact with steam, fatty acid feed, and water, to superheat the steam and preheat the feed to substantially the temperature of the still, and to generate said steam.

4. The process as in claim 2, in which all of the direct steam used for volatilizing fatty acids is generated and brought to substantially still temperature by means of heat recovered and absorbed from the hot vapors in. cooling and condensing therefrom distilled fatty acids.

5. The process of distilling fatty acids which comprises vaporizing such fatty acids with the aid of heat and a high vacuum, separating entrained unvolatilized material from the hot vapors by contacting all of such vapors with hot deflecting surfaces without substantially reducing their temperature; and preheating the fatty acid feed to substantially the temperature ofthe still by subsequent indirect generally countercurrent contact with the hot vapors free from entrained unvolatilized material, the various steps of said process being performed in chambers provided with in a single common outer shell.

6. The process of distilling fatty acids which comprises vaporizing such fatty acids with the aid of heat, direct steam and a high vacuum, separating entrained unvolatilized material from the resulting vapors by contacting all of such vapors with hot deflecting surfaces without substantially reducing their temperature, and passing the hot vapors over cooling means in indirect heat-exchange relationship to generate said direct steam from water supplied to a portion of said cooling means and to heat the fatty acid feed to substantially the temperature of the still, and contacting within the still the steam so generated and the heated feed for the volatilization of fatty acids, the various steps of said process being performed in zones provided Within a single common outer shell.

7. The process of claim 6, in which the hot vapors, after the removal, of entrained material,

are brought successively into indirect generally countercurrent contact with steam, fatty acid feed, and water, to superheat the steam and preheat the feed to substantially the temperature of the still, and to generate said steam.

8. The process of vacuum-steam distilling fatty acids which comprises vaporizing such fatty acids while intimately contacting them with a stream of water vapor, separating entrained andunvolatilized material from the resulting hot vapors by contacting all of such vapors with hot deflecting surfaces, passing the hot vapors over cooling means in indirect heatexchange relationship to generate and superheat steam and to preheat the fatty acid feed to substantially the temperature of the still, and bringing the steam so superheated and in controlled amount into intimate contact with the liquid fatty acids being distilled, the various steps of said process being performed in zones provided within a single, common outer. shell.

9. The process as in claim 6, in which all of the direct steam used for volatilizing fatty acids is generated and brought to substantially still temperature by means of heat recovered and absorbed from the hot vaporsin cooling and condensing therefrom distilled fatty acids.

10. .The process of distilling fatty acids which comprises vaporizing such fatty acids from a body of liquid undergoing distillation with the aid of heat and a high vacuum, separating entrained unvolatilized material from the resulting hot vapors by contacting them with hot defleeting surfaces without substantially reducing their temperature, and passing the hot vapors in indirect heat exchange relationship successively and countercurrently with fatty acid feed and coolingwater, whereby the fatty acid vapors are condensed and the fatty acid feed is heatedlto substantially the temperature maintained within the still, and steam is generated from said cooling water by said condensing fatty acid vapors, adding said heated feed to the liquid undergoing distillation and supplying additional heat thereto while at still temperature and pressure to provide the latent heat necessary to volatilize the fatty acids.

11. The process of vacuum-steam distilling fatty acids which comprises maintaining a body of fatty acids undergoing distillation at a substantially uniform temperature, continuously supplying to the body of fatty acids undergoing distilla tion, at substantially. the same temperature, the latent heat necessary to convert said fatty acids into fatty acid vapors, contacting said fatty acids undergoing distillation with a stream of water vapor in controlled amounts preheated to substantially the same temperature, the water vapor so used being generated by indirect contact, in heat exchange relationship, of cooling water and the hot fatty acid vapors by heat recovered from and absorbed from such fatty acid vapors in hot deflecting surfaces and subsequently condensing the fatty acid vapors thus freed from unvolatilized material, both the separation of entrained unvolatilized material and the subsequent condensation of the fatty acid vapors being performed in zones provided within a single com mon outer shell.

13. The process of distilling fatty acids which comprises vaporizing such fatty acids from a body of liquid undergoing distillation with the aid of heat, direct steam and a high vacuum, separating entrained unvolatilized material from the resulting hot vapors without substantially reducing their temperature or pressure, passing the resulting hot vapors before any substantial reduction in temperature in indirect contact, in heat-exchange relationship, with water, fatty acid feed, and steam, whereby the said fatty acid vapors are condensed and steam is generated, and the steam so generated, in controlled amounts, and the fatty acid feed are heated with heat recovered from said fatty acid vapors to substantially the temperature maintained within the still, and after being so heated are brought into direct contact with one another within said body of liquid for the volatilization of fatty acids therefrom, the various steps of said process being performed in chambers provided within a single common outer shell.

v 14. In the distillation of fatty acids by volatilizing the fatty acids from a body of liquid undergoing distillation with the aid of heat and a vacuum with subsequent condensation of the volatilized fatty acids, the steps of separating entrained unvolatilized material from the fatty acid' vapors rising from a body of fatty acids undergoing distillation without substantial drop in temperature or pressure or substantial condensation of volatilized fatty acids and fractionally condensing fatty acid fractions having different boiling points by passing the vapors through chambers maintained at substantially uniform pressure and at progressively lower temperatures for the separation of fatty acid fractions having different boiling points, the various steps of said process being performed in chambers. provided within a single common outer shell.

15. The process as in claim 1, in which the fatty acids are vaporized While contacting them with a controlled stream of superheated direct steam, and in which such steam is generated and superheated by indirect contact of water and steam generated therefrom with the hot vapors.

MARTIN HILL ITTNER.

CERTIFICATE OF CCRRECTION.

Patent No. 2,202,007. May 28, 191 0.

MARTIN HILL ITTNERQ It is hereby certified that error appears in the printed specification of the above numbered patent requiring correetioneus follows: Page 1 first column, line 58, for "in" read --to; page 6, first col umn, line 214., for

the word "nut" read --out page 7, first column, line l for "214.0" re ad 214009; second column, line 65, elaim5, for "with in" rea d --within--; and that the said Letters Petent should be read with this correction therein thatthe same mey conform to the record of the case in the Patent Office.

Signed and sealed this 50thday of July, A. D. 191m.

t Henry Van Arsdale, '(Seel) Acting Commissioner of Patents.