US1398856A - Method of fractionate distillation - Google Patents

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F. HANSGIRG. METHOD OF FRACTIONATE DISTILLATION.

APPHCAT'ION FILED NOV-7,1919- I Pa MM. 29, 1921.

F. HANSGIRG.

METHOD OF FRACTIONATE DISTILLATION. APPLICATIOILFILED NOV.7,1919.

1,398,856, I Patented Nov; 29, 1921.

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F. HANSGIRG. METHOD OF FRACTIONATE DISTILLATIONL APPLICATION FILED NOV. 7. 1919- Patented Nov. 29, 1921.,

4 SHEETS-SHEET 3.

F. HANSGIRG.

METHOD OF FRACTIONATE DISTILLATION.

APPLICATION FILED NOV. 7, 1919- Patented Nov. 29, 1921.

4 SHEETS-SHEET 4.

FRITZ HAIN'SGIRG, F GRATZ, ATl'STRIA.

METHOD OF FRACTIONATE DIS'IILLA'IION.

T 0 all whom it may concern:

Be it known that I, Doctor F nrrz HANS- GIRG, chemist, a citizen of the Republic of Austria, residing at Gratz, Korosistrasse 48, Austria, have invented certain new and useful Improvements in Methods of Fractionate Distillation, (Austria, application filed May 28th, 1916, and additional applications filed October th, 1916, and July 30th, 1917; Rumania. appl. filed June th, 1918; Germany, appl. filed October 2nd, 1916; Hungary, three applications filed October 15th,

1918,) of which-the following is a specification.

In the distillation of crude oils, mineral oils, tarry and fatty oils, fatty acids and the like, as at present practised, the material under treatment is usually heated to the required temperature by means of coal or oil fires. Where the liquid is of such a nature as not to mix with water, steam is usually blown into, it during the heating; and in the case of substances which readily decompose and which have a high boiling point, distillation is carried out at low pressure.

All of these methods have the drawback that the heating surface is very small in comparison with the volume of material to be treated; and for that reason, it is necessary to have a great-difference in temperature between the heating surface and the material undergoing distillation. It is due to that fact that pyrogenic decomposition frequently occurs when a decomposable liquid comes in contact with a highly heated surface; and, similarly, that the vapors given off become separated into their constituents on contacting with the hot walls of the still, whereby the quality of the products of distillation is considerably lowered if no destructive distillation wasintended.

According to my invention, the above drawbacks are overcome by keeping as low as possible both of the most important factors involved in decomposition during distillation, namely the temperature at which decompositionis effected, and the time which is necessary for decomposition. With this object in View, there are inserted into the liquid to be distilled heat-transmitting bodies of large surface area which are heated by the passa e of electric current therethrough'. Such bodles enable a large amount of heating energy to be transmitted to the liquid at a slight difference of temperature between ways occur in continuous distillation.

hydrocarbons,

Specification of Letters Patent. I Patented NOV. 29, 1921'. Application filed November 7, 1919. Serial No. 336,526.

the liquid and the bodies, and at a high speed of distillation. As this method further permits the regulation of the current supply to the heating bodies with the greatest nicety, it enables the separation, with an exactness hitherto unknown in practical distillation, of the constituents of the liquid without the constant fluctuations whichTalle present method thus offers a high degree of efliciency with a minimum of current expenditure and with the smallest possible apparatus.

It has been heretofore proposed to utilize electrical resistance heat for distilling liquid but not for the purpose of fractional distillation; nor was there any perception of the advantages offered by the employment of an electric heating current at a low and constant difference of temperature between the liquid and the heat-transmitting body. It is possible to distribute resistances having large surface areas equally throughout the entire body of liquid, and in that way to obtain heating surfaces which may be even a hundred times as great as the outer heating surface of the still. even if the latter is of the fire tube type. Thus, not only can large quantities of heat be transmitted at low temperature difference, but the amount of heating energy which can be supplied instantly is so great that the velocity of distillation may be raised for example, a

hundred times as high as when effected by external heating; this shortening of the time consumed in the operation rendering it possible to utilize all of the heat supplied for evaporating purposes without any pyrogenic decomposition taking place. The technical advantages derived from the use of resistances of large surface area are: (1) sharp speeds, and the fractions obtained therefrom 'will have different boiling points;'and if it is attempted to further fractionate the volamentioned above as necessary to avoid detile products of distillation in each still by fractional condensation, for instance by means of dephlegmators, it will be found that the fractions obtained in the individual dephlegmators will show different compositions, not only on account of the different speeds of the stills but also on account of the fluctuations in the temperature of the outer air. By utilizing an electric current, however, in continuous distillation, it is possible to supply to each still exactly the same amount of heat in each unit of time, thereby obtaining a constant working speed for all of the stills and, hence, constant fractionation; and it is also possible, in like manner, to maintain the dephlegmators independent of atmospheric temperature changes.

One of the most important requirements for the distillation of decomposable substances is the transmission of the necessary amount of heat at as small a difference of temperature as possible time. Toefiect this, it has been proposed to use apparatus equipped with coils of tubing, or with analogous devices, through which steam is caused to pass in order to obtain the desired large heating area. Such devices may, however, be employed only in the distillation of substances having a very low boiling point. lfit should be attempted to utilize steam coils for the distillation of an oil having a boiling point of 350 (3., such method would prove most uneconomical because it would be necessary to use superheated. steam at a temperature of at least 370 0., having a low specific superheating heat which could only be utilized fora drop of 20, while the greatest part of the heat which is contained in the steam as evaporating heat could not be made useful for the process. Moreover, it is impossible to transmit large quantities of heat by means of superheated steam in steam coils at a low difference of temperature, because the superheated steam flowing through the coils at a high velocity is a poor heat transmitter and is incapable of transmitting a great amount of heat to the coils (even if they have a large surface area) excepting when sufficiently high temperature-differences are present. Hence it will be apparent that the use of steam coils for distilling liquids having a high boiling point, renders a rapid distillation at low temperature-differences either impossible or very uneconomical. On the other hand, rapid distillation can be obtained without superheating the liquid by distributing electric resistances havin large heating surfaces throughout the liquid, since that method enables any desired amount of heat, almost without limit, to be transmitted at low temperaturediflerences and so fares I know that is the only way ef'febtaining the two conditions possible and in the shortest aseaeee composition.

Exact tests show that the number of-watts radiated pg a resistance submerged in a liquid' is W. AT in which K is the radiationconstant of the resistance and AT is the difference in temperature between the resistance and the liquid. Obviously K can be made very great if T is very small, and W can be great, so that the liquid can be evaporated without bringing it' into contact with any surfaces having a temperature greatly in exgess of that of the boiling point of the li ui he great economy of the electric method of distillation resides in the fact that nearly 100% of the energy supplied is consumed in the form of evaporating heat as a result of are; sufficiently protected by heat-insulating material against external radiation and heat-transmission. Furthermore there is the possibility of very exact regulation of the current supply, and of pre-heating the cool liquid by means of dephlegmators, which latter can be kept at a constant temperature by an additional electric heating means of suitable character; and in that way the highest heating economy possible and the sharpest fractionation may be obtained by pre-heating the liquid step by-step. For example, 7000 kilograms of mineral oil can be distilled in 24 hours in a still having a capacity of about 500 liters, a quantity which would ordinarily require a still having a capacity of about 20 tons.

The electric resistances may have the form of bodies constructed of suitable resistance material and-immersed in the liquid so as to be in direct contact therewith, or of bodies in whose walls the resistances are inclosed; and it is also possible to utilize hollow ra diators'through which an electrically heated liquid or fluid is caused to pass, in which case the heating of the liquid to be distilled will take place in an indirect manner, instead of by direct contact. In the latter instance, coils of tubing may be employed, or double-walled or double-bottomed containers.

Another way in which the invention may be carried out is to utilize a non-conducting, electrically-heated liquid to vaporize the liquid to be distilled; but in such case it is fixed temperature by means of additional liquid to be distilled which flows. against it;

According to the same method, it is equally possible to let thel-liquid flow over surfaces which are heated step by step by electrical resistances, each to a certain temperature, and in this way separate the components in the quickest possible manner. 'So, also, it

is possible to let the liquid flow over an elec-.

trically-heated surface or resistance to an empty receptacle, and to maintain the resistance body at a temperature such that a fractional vaporization will take place upon its surface, the remainder of the liquid being allowed to accumulate in the receptacle. From the latter, the liquid is caused to flow over a second resistance element which is arranged in a second receptacle where the same action takes place at a higher temperature, and so on, thereby obtaining perfect fractionationin a continuous manner. Normal pressure or vacuum may be maintained in the several receptacles.

The heating elements arranged in the receptacles may be of different constructions;

they may be in the form of hollow-conduits provided with perforations through which the liquid or gaseous heating agent may escape into the liquid to be distilled. The resistances arecalculated in such a manner that a difference of only a few degrees exists between the resistance heat and the boiling point of the liquid, or its fictitious boiling point when the pressure of the injected gases or vapors is taken into account. Saturated or superheated liquid vapors, such as steam, gasolene vapors, and hydrogen, nitrogen, methane and other gases may in this way be blown into the liquid under treatment; and the vapors and gases may either be preheated before use, or may be heated by their passage through the resistance bodies.

The invention may be still further uti-.

lized to eflect distillation without decomposition by means of dehydrating substances.

It is already knownthat highly dried and clean distillation products would be obtainable by distilling mineral oils in the presence of dehydrating substances such as akali metals, were it not for the necessity of injecting steam to lower the boiling point.

(By employing the. present method of distillation, however, according to which liquids having a high boiling point may be distilled without requiring the injection of steam, it is possible to effect distillation in the direct presence of sodium, potassium and other dehydrating substances. Byadding such substances to the liquid under treatment, distillates can be obtained which are free both of water and of the added chemicals themselves and their reaction products. As a result of the distillation of mineral oils in this manner, not only is every trace of water driven oil", but also all sulfur, all substances of a sour or phenolic character and all resinous substances which incline to a later polymerization are bound in such a manner as to remain during distillation as parts which do not become volatilized at the highest temperatures. In that way, oils of light gold-yellow color even at the highest viscosities are obtained, thereby rendering wholly unnecessary-any subsequent refining with sulfuric acid and sodium hydroxid. These oils are most suitable for use in electric transformers and switches, as their insulating property is such that they are pervious only to very high voltages. They can be heated to temperatures of from 200 to 300 C. for hours, and they may remain in direct sunlight for days without showing the slightest change in color.

In the accompanying drawing, Figure 1 shows by way of example a plan view of a distilling plant for carrying out the invention; I

' gig. 2 is a vertical sectional view of the sti s; v

Fig. 3 is an enlar ed vertical cross-section on the line A-B -D of Fig. 1;

Fig. 4 is a detail view of one form of resistance element;

Fig. 5 is a cross-section of Fig. 4; and I Fig. 6 is a detail sectionalview showing a coupling which may be employed in connection With the resistance element.

The oil is forced by a pump 1 through the piping 2 into the oil reservoir 8, wh'ence it flows through pipe 4 into the heater 5 where it is subjected to a preliminary heating. From the pro-heater it passes through piping 8 into and through the successive stills 6 6, 6 and 0, each of which contains the electrical resistance units 7, the latter being distributed throughout the entire stills and having sufficiently large heat-trans mitting surfaces to obtain a low temperaturediflerence between the liquid undergoing distillationand the heating body or unit, as previously explained. The form of still illustrated in the drawing is more or less diagrammatic and is given by way of example only; and the number of stills comprised in the apparatus (four in the present instance) may be increased or decreased according to conditions. Each still is equipped with an inlet valve 8 and, also, with some suitable device for regulating the current supplied to the resistances, the regulating devices being omitted from the'drawing-as forming per 86 no part of the actual inventlon'. From thelast still, the residuum is Serial No. @7,195.

returned by piping 9 to a counter-current device 10 which is located in the pie-heater 5 and may be of any preferred type, the preheater having a resistance unit or body 7 therein. The residues are drawn ofl from the pre-heater by a pipe 12.

The respective stills have coolers 13, 13", 13 and 13 connected to them; and between each still and its cooler there may be interposed a suitable air-cooling device or dephlegmator. The products of distillation pass from the stills throu h piping 14 into receptacles 15, 15", 15 an 15, all of which are connected by'piping 16 with a common vacuum tank 17; and the cooling water passes through inlet and outlet pipes 18 and 19, which communicate with the coolers.

The resistance units may be in the form of hollow conducting bodies, as indicated at 20 (Fig. 4:), which may be arranged in zigzag relation and may be constructed of flattened tubing, the walls of which may have perforations 21 for the escape of the liquid or gaseous heating medium therethrough into the liquid to be distilled. In order to assure more efiective operation and quicker distillation, the heating medium may be led from two or more sides to the stills by exteriorly-located mains 22 which are insulated from the conductive resistances, to which the cables 23 are attached, by means of stufling boxes 24 and 25, both constructed of china clay or other insulating material (see Fig. 6).

The arrangement shown in Fig. 3 may be utilized for non-continuous distillation, it being merely necessary to interpose a controlling valve between the cooler and the receptacle 15 in order to separately collect the single fractions. Cooling may be partly effected by the liquid itself, and in that way it is possible to make use of part of the heat of vaporization. Each of the stills may, if desired, be covered with a covering of heatinsulating material so as to be protected against losses by heat-radiation.

No claim is made herein for the apparatus disclosed in the drawings, since such apparatus forms the subset of a divisional application filed on or a out November .29, 1920,

naeaeee I claim as my invention: L'A method of fractional distillation, comprising the steps of supplying an electric current to electrical resistances having.

large heat-transmitting surfaces, and maintaining a constant, low temperature-difference between said surfaces and the liquid undergoing distillation.

2. A method of fractional distillation, comprising the steps of passing an electrically-heated, non-conducting fluid through a hollow body immersed in the liquid to be distilled and having relatively large heattransmitting surfaces, and maintaining a constant, low temperature-difference between said surfaces and the liquid undergoing distillation.

3. The herein-described method of fractional distillation, comprisin the steps of subjecting the liquid to be i'stilled to the action of an electrically-heated, non-conducting fluid at a constant, low temperaturedifi erence.

4:. A method of fractional distillation, consisting in forcing an electrically-heated, non-' conducting fluid through perforated, hollow resistance elements into the material undergoing distillation.

5 A method of fractionating liquids the constituents of which have difierent boiling points, consisting in flowing such liqui over a plurality of separate electrical resistance elements each of which is heated to a difl'erent but constant temperature so as to vaporize a certain fraction by contact with the heated surface of each of said elements. I

6. The herein-described method of fractional distillation, comprising the ste s of adding a dehydrating substance to the iquid to be distilled, and subjecting the resultant liquid to the action of electrically-heated resistance means at a constant, low temperature-difference.

In testimony whereof I afiix my signature in presence of two witnesses. 1

DR. FRITT'HANSGIRG.

Witnesses Lnorom SGHALLER, WILmLM KARNER.

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