US1541274A - Process of distillation - Google Patents

Description

June 9, 1925. v 1,541,274

H. F. PERKINS PROCESS OF 'DISTILLATION Filed Jan. 17, 1922 zln'uc nfor Wen/E52 4 9,

Patented do $1, i925 roves HARRY FRANKLIN PER-KENS, 'ZPORJT ARTHUR,

PROCESS F DISTILLATIGN.

Application filed January 17, 1922. Serial No. 529,862.

To all whom it may concern:

Be it known that l, HARRY F. PERKINS, a citizen of the United States, residing at Port Arthur, in the county otileflerson and '5 State of Texas, have invented certain new and useful Improvements in Processes of Distillation, of which the following is a specification. v This invention relatesto processes of distillation; audit comprises a method of distillation particularly adapted to petroleum products, although useful in other relations, wherein vapors coming from a suitable still are passed successively through two or more equilihreting zones of controlled temperature, each successive zone diiiering from its 1 redecessor slightlyin temperature and each eing kept at substantially uniform temperature throughout its length and throughso out its width, and are then condensed; and it also comprises as a new combination of apparatus elements, it suitable still and a suitable condenser with a plurality of jacketed casings acting as temperature stabilizi means lowt/ed hetween the vapor outlet of the still and said condenser, each casing provided interiorly with a heatconductive aching of metallic nature; all as more in" y hereinafter set forth and as claimed.

As is well known, petroleum oils are mixtures of a t number of different oily hydrocarbons, many of which difi'er from.

each other very slightly in composition, hoil- 7 ing point and other characteristics. In any petroleum oil there are oily hydrocarbons, or groups of hydrocerbons, out widely separated boiling points, hut there are also hydrocarbons of intermediate boiling points; and for this reason, under the well known laws governing volatilization of miscible liquids, it is substantially impossible on a commercial scale, or even in a laboratory way, to separate any oneof these individ ual hydrocarbons by distillation, or even to separate them in an. sharply marked groups. The boiling points of the hydrocarhons of the composite mass are so interlinked hy the presence of the intermediate hydrocarbons as to preclude sharp separations. The ordinary lractioneting columns, wnstant temperature stillhcaids, etc. adapted for the separation of two or a few components do not here give clean cut, definite fractions, in commercial refinery practice,

, ZODGS.

petroleum. hydrocarbons are distilled, so to speak, in groups; the crude oil is distilled with steadily rising temperature togive a few fractions or cuts; and these cuts are then generally redistilled to give new cuts boiling Within certain temperature limits gasoline, kerosene, etc, The cuts however always, so to speak, overlap; the kerosene contains oils which might usefully be contained in the gasoline cut and vice versa.

It is an obiect of the present invention to provide a method of distillation which will give at once cuts of more definite end homog-v enous nature than those edorded by the usual methods and with such a, distribution of the various hydrocarhons as will give a large volume of the desired cuts. in so doing, it is necessary to pay careful attention to the details of the operation and this is done in the present invention.

At any point in a refluxing partial condenser handling petroleum vapors, whether an ordinary runback, a constant temperature stillhead or a fractions-ting colun'in, liquid endvapor are in contact and striving to come to an equilibrium at the local temperature. Attainment of equilibrium is not instantaneous, The liquid is (or should'he) that which will just condense at this temperature; the vapor that which will just not condense. The position of the equilibrium is quite sensitive minute tempera-' ture changes; and since the vapor readily dissolves in the'liquid with evolution of heat, or re-evaporates with absorption of heat, ecoording to the composition of the vapor phase, t e equilibrium point is constantly shifting. With any shift in the equilibrium, the volume of vapor and that of liquid undergo reciprocal changes. In order to secure and fix an equilihrium, time is required; and it is necessary to give u large area of contact between vapor and liquid in e, constant temwrature zone of suitable size.

in the present invention in order to fix and maintain the equilibrium the vapors prior to going-to a condenser are sent through a plurality of constant temperature Zones of suitable length with merely a slight difference in temperature hetweenadjacent At least two are used; and more may be employed with advantage. in each zone conditions are maintained so that the equilib rium itself can be relied upon to establish All) and maintain the specific temperature desired; the desired final equilibrium being approached in the zone next before the last and finally definitely set inthe last zone. It is desirable that the temperature drop between zones shall be small but definite. A

temperature drop results in condensation to act as a cooling medium in the sense oflowering the temperature. Distillation conditions are so adjusted as to have the vapors enter the final zone at nearly the temperature therein prevailing, allowing final adjustinent and establishment of equilibrium to take place in the zone itself. Any sudden or violent cooling within the zone, with the attendant copious condensation whether due to air cooling or cooling by circulating liquid would defeat my purpose. 1 customarily use the temperature regulating liqaid in a jacket surrounding the zone. llts temperatureloeing very nearly in the zone itseli it obviates practically any influence oil the air temperature and is, to that extent a sort oil thermal insulating means.

In commercial specifications of volatile petroleum oils, it is customary to specify the overpoint, or the point at which the first drop distils over and the end point, or the point where all the oil is volatilized. in practicing the resent invention in distilling petroleum oi s to make any particular product, such as gasoline or kerosene the last of the constant temperature zones is maintained as nearly as possible at the end point oi the out to be made; say within a or ,6 degrees ll. above or below, and. the next to the last none a temperature just above "that in the last zone. in the next to the last zone in is the object to set an equilibrium with a little more of the higher boiling oils in the vapor phase than are desired in the final condensate to be made, thereby s curing vapors richer in low boiling oils, and then take out this excess of high boiling oil in the last zone. To aid in preserving even or equalized temperature within each zone it is as stated jacketed for circulating a temperature-controlling fluid, such as water, oil or steam. Coils may be used but the jacket is desirable. And in order to obviate as much as possible local internal temperature diderentials which would interfere with the equilibrium each zone is provided with packing oi some metal with good heat conductivity. The internal temperature should not differ more than, say, 10 F. between any two points; as for example, between periphery and center in any horizontal plane. Iron, copper or nickel may be used. Themetal packing not only provides for transverse and longitudinal equalization of temperature but gives a large area contact between vapors and liquids with the mass of liquid trickling over the metal comparatively small as compared with the mass of such metal; The mass of metal acts as heat-stabilizing means. The packing may be of any shape or arrangement giving good thermal conductivity across the zone with ample contact between liquid and vapor and not too much friction to oppose passage of vapor. Balls, pellets, disks, rings etc. may be used. Balls of nickel or copper may be used. Steel wool makes a good packing but for large apparatus metal of coarser cross-section is better.

Where flat disks, rings, etc. are used, it 15 a desirable that the packing have at leastsome of inclined, say about 1 degree. The packthe horizontal surfaces slightly.

lug should be such as to give a free vapor path of somewhere between 0.1 and 0.2 square inch per gallon per hour capacity; the free path being somewhat greater at the entrance than at the exit end of each constant temperature Zone. I do not desire thatany vapor be more than, say, threethirty seconds or": an inch away from a surface of heat-conductive metal and the packing should be suitably constructed or arranged to ive this result. The speed of passage of the vapors through the zone may be around 250 feet per minute. @perating in the manner just described, vapors are first brought to equilibrium with liquid condensed therefrom (and the liq-' uid, of course, with the vapors) at temperature just above the end point desired, the condensed liquid draining away and the vapors being left with a little more high boiling component thanis desired in the final condensate.

ature with their condensate at the end point desired. After establishment of equilibrium, the equilibrized vapors are sent to the usual type of condensers and condensed to give the cut desired. The result is the production ofa comparatively large volume of the product desired and of out which is more homogeneous than usual. in making a distillate marketable as gasoline under the present invention, good merchantable gasoline may be directly distilled from crude oil in quick operation and the volume of merchantable gasoline thus obtained is greater than that made in other ways even with repeated distillations.

In the continuous distillation of crude oil,

The vapors are then again brought to equilibrium at a lower tempen llll) the oil is sometimes passed from end to end of a long horizontal cylindrical still, vapors being taken d at a plurality of points along .the'length and sent up through de-' hlegmating towers to give successive cuts. n this invention the successive vapor offtakes are provided; with equilibrizing zones of the described character, each being maintained under'conditions to make one particular cut, or several groups-of zones in series may be used in one vaporoutlet-to give desired cuts.

l have so far described the application of my invention only to distillation cuts made other, giving a section which is, so to speak,

' rovided with reflux connections leadwithout the aidof steamr "The process, however, may be applied also to cuts made by distillation withepen steam orgas such as hydrogen, In so doing, however, the temperature maintained in the last equilibrating zone is the end point of the desired fraction in distilling under a vacuum, or reduced prem se equivalent to the proportion of steam orv gases in the vapors in making thecut. Water, of course, is a body boiling at a much lower temperature than the cuts which are made with the aid of steam distillation and}. the presence or absence-of water vapor in the vapor under treatment in the equilibrating zone. makes no difieronce in obtaining the desired type of equilib rium, i 1 v lo the accompanying illustration l have shown, more or less diagrammatically, certain within the describedinvention and capable of use in the performance oi the stated process, ln'tltis showing the figure-is view, partly in elevation and partly in section, of a suitable apparatus, De-

-. passage of vapors tails ct condensing means, tiring means, etca,

have been.

- in this l is a conventional representation of furnace chamber provided with suitable tiringmeans, Waste gas outlets,

etc, (not shown) and 2 isa conveuitional showing of? one end of an ordinary cylindrical still mounted therein. This still may be one of stated continuous type stills having a olurelit of successive va or oil-'- t it takes clot-1g its length Vapors leave the still through vaporoutlet 3, having the usual sloping runbaclr portion 4:. The vapors pass successively through a plurality of zones. Two, A and B, are shown, but more may be employed. As shown, A is composed of an inner steel or iron casing 5, provided with temperature maintaining jacket 6 having an inlet 7 andoutlet 8 for a suitable fluid oi suitable temperature, such as steam,

oil, hot water, etc. Within, this casing is provided Will! a metallic pack ng 9. As

abown. this packing is composed of metal disks in staggered horizontal arrangernent The disks may be circular, hexagonal, octagonal. square. etc. As shown, the disks are somewhat thicker on one side than the F. higher,

mg condensate back into the still. As a rule-the condensed oils are sent back to the still though they may of coursebe directed elsewhere. It is best to-carry the refluxed liquidv through conduit 11 to a point near the bottom of the still. Zone A. at its top opens into B giving opportunity for unrestricted rem A into B. B is provided with an individual jacket 12 having supply .13 and outlet i l for a temperature maintaining fluid. In B, as in A, occurs the metalpacking 9, the packing as shown being continuous through A and B. Purified va pors leave B through vapor outlet 15, lead mg to'a suitable condenser, not shown. The temperature controlling fluid may pass as shown from the outlet of the jacket 05B...-

to the inlet of the jacket of A by connections,

In certain cases, the jacket of one of these sections may be omitted and air coolin relied upon, but this it do not recommend lin use. oi this apparatus, presuming that a gasoline cut with an end boiling point of,-

suitable say, 410 F, is to be obtained from crude oil, still. 2 is charged with the crude oil I and firing resorted to in the usualw waye- Zone B is then kept at its top at about 4-10.

Fr, or within the stated limits of tolerance,

and zone A. at a tem erature l or 5 degrees lotion with the production of grouped hydrocarbons in clearly cut groups becomes very efficient and a larger yield than ,usual eta gasoline with the desired end point is obtained. 'lnstead of using crude oil, naturally, a distillate, such as naphtha or other oil mixtures may be used in 2. The apparatus may be used in exactly the same Way for giving large yields ct uniform kerosene or of any other usual fraction or out.

While I have designed this invention more particularly for use with petroleum oil and other mineral oils, such as the shale oils, it may be of course used in other connections, as in obtaining fractions of coal Under t ese conditions distilloo tar of'greater' uniformity with fewer dis- 1 tillations than is usual,

What ll claim is I I ,1. lo the distillation 0t" fractions or cuts of petroleum oils the process which. comprises producing vapors of the oils to be distilled, transmitting said vapors in a tortuous pathway through a metallic packing of material freely conducting heat and postuai vapors to eiiord such cut.

.2. In the prccess of claim 1, the method which consists in positively controilin the temperature in each body of packing Within IOdegrees Fahrenheit es a maximum (tifference between any two points in such hcdy.

3. In the process cf claim the improvement "which comprises transmitting said' vapors in said tortuous pathway at a distance net greater at any point than about teezeeve three thirty-seconds of an inch time said metallic packing.

4. 1n the process of claim 1, the improvement which (3011113315 35 transmitting said vapors through a, tcrtucus pathway cf some whet larger cross section at the entrance end then at the exit end 5. In the process of claim 1, the improvement which comprises giving e free total Vapor path to the material having a cross sectional area amounting to between onetenth square inch and two-tenths square inch per gallon of distiilate delivered per hour.

In testimony whereof, I have hereunto affixed my signature.

HARRY FRANKLIN

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