US1523497A - Apparatus for fractionation - Google Patents

Description

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H. G. SMITH APPARATUS FOR FRACTIONATION Filed Dec. 18, 1920 Patented Jan. 20, 1925. p a

UNITED STATES PATENT OFFICE.

HERSCHIQL (3-. SMITH, OF SWARTHMORE, PENNSYLVANIA, 'ASSIGNOR TO THE AT- LAN'IIC REFININGCOMPANY, OF PHILADELPHIA, PENNSYLVANIA, A CORPORA- TION OF PENNSYLVANIA.

APPARATUS Fon FRACTIONATION.

- Applicationfiled-December 18, 192a Serial No. 431,552.

To all whom it may concern: 7 fuel and for mixture withlighter naphthas Be it known that I, HERSOHEL G. SMITH, for motor gasolene. My apparatus also finds a citizen of the United States,-residing in application in increasing the yield of gaso- 55 Swarthmore, county of Delaware, and State lene or other fraction of crude petroleum,

of Pennsylvania, have invented new? and having a given dry point or boiling point.

useful Improvements in Apparatus for For an understanding of my invention Fractionation, of which the following is a and an illustration of some of the various ifi ti n. forms my apparatus may take, reference is 60 My invention relates to apparatus for h had th p y g e ga 1h 10 fractional distillation of mineral oils or whlehi hydrocarbons, whereby high selectivity as 1 l e e p y 111 e h, of pbetween diflerentfi'actions or cuts is ob- 'e emhedylhg my 1I1Ve11t10 nt i bl d the by securing i a F1gs. 2 and 3 are vertical sectional views 65 of yield of a fraction or cut of desired charof lhedlfied forms of apparatus Whleh may acteristics. be mp y d. v

In accordance'with my invention, the oil g- 4 1S elehm View, 011 large Scale, f containingthe desired cut or fraction'is y f Pe g e P y subjected to distillation, yielding a mixture g to S represents Stlll 7 of vapors ofoils of various boiling points, Whose contents y he mlsed t0 a l th yapor i t b i Passed upwardly temperature by fire or other source of heat in heat transfermelation with downwardly external thereto, Steam h rged flowing condensate containing largely conf the Perforated P p t Whleh Steam densed vapors'of higher boiling point oils, in eendueted fmgh the plpe 6. Or the 7 subdivided ,form or well distributed condi-' beefing of the stlll contents y be q tion, the extent or duration of the heat Rhshed y hethexterhel fihlhg end PP transfer relation being such as to yield tleh of Steam Wlthln h 111- sharply defined or selected cuts or fractions, The Vapors 0f h St111 are Conducted the degree of sharpness or selection of a cut through t p P p 11118 V, In WhI h or fraction being controlled by maintainy he lheelted a thermometer to the 30 i it bl diff b t th t m chamber an the bottom of the tower structure of the vapor mixture from the still and ture eempnelhg the shell h Sheet' met31 the vapor constituting the selected fraction 9 ether'ehltehle meterleh having edlaeeht or cut, such diflerence in temperature being pp end the manhole, f h e ee 85 procured or controlled by suitably conh upper d at 9- h t fl with trolling diminution of the total heatcontent h hettelh of the ehalhhel' the e a i th Vapor i t pipe or l1ne D extend ng into the interior In accordance with my invention,- the vat the stln: The t e e p e y Covered por mixture is cooled by bringing into con: Wlth heat lhshletlon, lhcheated 90 tact therewith condensate or liquid 'resu-lt- Aheve t ehemhelf d 15 the glflu 40 ing from the condensation of vapors of the g e s above Whleh e filhhg h desired fraction or cut. or a distillate, liquid term? of t tower Sultahle helght, 15 h or condensate ofsimilar, characteristics, and p h 7, efehy Sultable f r. Thls by controlling the quantity or temperature, p e eehetltutes numerous P 95 or both, of thea'coolin'g condensate, the deh as vltlflfied earthenware, fermlhg e gree of sharpness of the desired cut is conmultitude of lhterstlees end Passagestrollable. As an example of various kinds andtypes My apparatus finds application in-the reof packing that may be employed may be fining of petroleum, and particularly in mentioned vitrified tower packing such as 100 producing therefrom any sharply defined used in manufacture or treatment of acid,

cut or fraction, as for example, sharply desuch as sulphuric acid. Such packing may fined fractionscf-n hthaandj kerosene or take any suitable form an example of which burning oil, the former utilizable for motor is indicated in Fig. 4, in which the external e, theliquid being deflected from said walls into the packlng j. I

Communicating with the space or chamit ber 12 at the upper end of the tower is the pors flows through the pi vapor line or pipe V in which may be inserted a thermometer c delivering vapors from the tower to the condenser worm or coil C disposed within a tank or receptacle 1 into-which cooling medium, as water, is introduced through the pipe 1' and carried off by the pipe 8. The condenser worm delivers through the pipe t into the receiving tank or condensate receptacle R from which the distillatemay be drawn off through the pipe it.

Through the pipe *0 controlled by valve w, condensate or distillate may be drawn from the tanlrl R by the pump at and delivered through the meter y to the pipe 2, which extends into the tower and delivers the distillate to any suitable liquid subdividing means or sprayer, an example of which is indicated at (L consisting of a tray receiving the distillate from pipe 2 and havlng notches and openings for allowing escape of the distillate, by gravity, in small streams.

The operationis as follows:

Assuming it be desired to procure sharply defined cuts or fractions of naphtha and kerosene, there ma be charged into the still S petroleum distil ate containing naphtha and kerosene. The still is heated or fired at suchvrate as to raise the charge to suitable temperature, which temperature may be increased at such rate as to effect the de-" sired rate of production of distillate or desired fraction. The mixture of evolved vae V into the chamber d and thence upwar ly through the interstices between and passages of the packingj, the vapors ofoils. of higher boiling points first condensing, and those of progressively lower boiling points condensing at greater heights within the'tower V6, with the result that there is an up-flowingstream of vapors and a downwardly flowing stream of condensed oils of. boiling points higher than that of the desired fraction or final condensate or product of sharply defined fractionation, these heavier oils flowing back into the chamber (1 and thence through the runback D into the still S.

By this upward flow of vapors and counter or downward flow of condensed vapors, dephlegmation takes place, in that heat exchange occurs between the rising vapors and descending oil, with the result that the vapors reaching the upper end of the tower are those of oils having more closely the same boiling'points than the oils of the vapors delivered by "the still through the vapor line V; and the boiling points of the oils whose vapors so reach the upperend of the tower e are lower than the boiling points of all the oils which are condensed within the tower and flow downwardly through the packing j. V

At thebeginning of the distillation the temperatures of thevaporsinthe pipes V and V may notwidely difi'er; in fact, they may be but slightly different, and thempors delivered 1nto the pipe V are those of naphtha, which are condensed in the coil G and delivered to the receiver B. As the distillation continues, the diiierencein temperatures registered by thethermometers c and c willfbe increased, particularly when there is pumped back through 'the pipe 2 to the spraying device a some of the distillate from the receiver R, such" distillate constituting the desired fraction or cut, i. e, the final product or final condensate; ,At the beginning of application of the distillate to the spraying device, the rate of delivery of the distillate may be small, and progressively increased as the distillation proceeds. As the amount of distillate returned to the tower is increased, the difference. between the temperatures registered by the thermometers c and 01 will increase, and at the end of the distillationperiod for procuring the naphtha fraction or cut this temperature difference may amount to about degrees F. i

Thereturned distillate efiects an accentuated coolinglor chilling, in that the distillate in descending through, the packing abstracts heat from the rising vapors, causing condensation therefrom of oils whose boil ing points are higher than that of the desired distillate or cut, the returned distillate by the consequent absorption of heat being vaporized, but the resultant vapors are those of the desired cut; and they'againpass off. through the pipe V to the condenser C and return to the receiver R as distillate along with additional distillate representing part of the vapors affected within the tower e by the distillate returning thereto.

The rate ofreturn of distillate to the tower is controlled, as by the valve w, and by so controlling therate of supply of distillate to the tower, the distillation and shar fractionation are controlled. A ter the aforesaid naphtha cut has been taken, a similarly sharply I defined cut of kerosene or burning oil of desired characteristics may be taken in similar way. After taking the kerosene out, there Will be left in the still a residuum which is principally gas oil which may be utilized for other purposes.

The naphtha obtained in accordance with the above described method may be employed as motor fuel, or may be mixed or blended with lighter naphthas, as casing head naphtha or gasolene, for producing motor gasolene.

In practicing the method as above described, the cost of fractionation, as measured in terms of heat units required or employed, is relatively low, the only heat losses being those occasioned by radiation from the apparatus, as the tower, and the heat delivered to its cooling medium by the condenser C. The heat loss in the condenser may be greatly reduced by using as the cooling medium delivered through the pipe 7' the oil to be charged into the still S when such still is used in a. continuous distillation process, as for example, when the still S is one of a 1 series of two or more interconnected by pipes through which there is delivered from one still, engaged in producing cuts of lower boiling point, oil or residuum to another still'of the series engaged in producing a fraction of higher boiling point.

In Fig. 2 the arrangement is similar to that described in connection with Fig. 1. However, the lower end only of the tower e is covered by heat insulation h, and for the remainder of its height it is enclosed in a stack or shell A, spaced from the tower 6, air being admitted to the space between the tower and shell through the inlet openings 6 Above the tower the stack is provided with a damper (1 whose position i 'con trollable at will by the member e The upper end of the stack may be provided with a removable cover 7.

The mode of operation is similar to that described in connection with Fig. 1, though in this instance heat is abstracted from-the tower into the air passing upwardly between the stack and tower 0. Control is effected as described in connection with Fig. 1, by return of distillate through the pipe 2 into the tower, the distillate being returned preferably at least during part of the operation.

In Fig. 3 the tower e is open at its upper end,- whereby uncondensed vapors pass upwardly through the tubes 9 disposed within the shell B into which air is admitted through the air doors h the air circulating around the tubes and passing upwardly through the hole 2' in the circular header with which the upper ends of the aforesaid tubes 9 communicate. The vapors of the desired fraction pass off from the header through the vapor line V as before.

The air after contact with the tubes 9 passes oil' through the stack 76, the air'draft elng controllable by the damper m The mode of operation is similar to that described in connection with Fig. 1, the vapors, however, being further differentiated or fractionated by the condensation taking place in the air cooled tubes distillate being returned as before through the pipe 2, at least during some stage of the operation.

By employment of the apparatus of Fig. 1, dephlegmation in addition to that by the higher boiling condensate from the vapor mixture is secured entirely by re-introduction of distillate into the tower. In Fig. 2 the additional dephlegmation is secured partly by the returned distillate and partly by radiation from the sides and upper part of the tower. In Fig. 3 the additional dephlegmation is secured partly by returning distillate, and partly by radiation from an air-cooled structure other than the tower.

While in the foregoing description reference has been made to return to the dephlegmator of distillate constituting the desired fraction or cut, it will be understood that other suitable material or oil may be employed, provided its characteristics are substantially similar to those of the desired distillate.

The above described method and apparatus make easily attainable great flexibility of control of conditions of distillation for a desired sharply defined fraction; and the method and apparatus lend themselves readily to large capacity operations, since the. apparatus may be constructed of any suitable or desired capacity.

lVhat I claim is:

Apparatus for producing a sharply defined fraction of petroleum comprising a still, a dephlegmating tower, deflector members spaced vertically from each other in said tower and having their peripheries in liquid-tight contact with said tower, said deflector members extending downwardly and inwardly to openings, packing material in said tower vertically continuous through said openings, a condenser, a vapor line extendin from said tower above said packing to sai condenser, and means for returning from the outlet of said condenser to said tower above said packing condensate discharged by said condenser.

In testimony whereof I have hereunto affixed my signature this 16 day of December, 1920.

HERSCHEL G. SMITH.

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