USRE16679E - And wirt d - Google Patents

Description

July 12 1927. JQ c. BLACK ET AL.

TREATMENT OF PETROLEUM PRODUCTS .Original Filed June l, 1925 INVENTORS ATTORNEY Reissued July 1,2, 1927.

" Re. 15,679l

UNITED STATES PATENTIOFFICE.

JOHN CrBLACK, F DESTREHAN, LOUISIANA? AND WIRT D. RIAL AND RAYMOND HOWES, OF LOS ANGELES COUNTY, CALIFORNIA, .ASSIGNORS TO PAN AME'RCAN PETROLEUM COMPANY, 0F LOS ANGELES, CALIFORNIA, .A CORPORATION OF CALI?- FORNIA.

TREATMENT 0F PETRGLEUM PRODCTS.

Original No. 1,592,329, dated vJuly 13, 1926, Serial No'. 34,024, filed .Tune 1, 1925. Application for reissue filed October 26, 1926.

Our invention relates to the treatment ofhydrocarhons and particularly of petroleum products italia-atingr a high sulfur content and other constituents that forni undesir- '5 able substances or compounds, one ot the1 chiel.' purposes of our invention heing.to' treat Synthetic petroleum products with a View to removing all or the highest percenta e of objectionable suhst anccs and one of the y o of our inventioi-i being to provide a method by which crude petroleum products maybeeconomically treated for the purposel I nated, connected relation Yin which they function to carry out the niethodI either by hatch or in continuous manner.

This invention relates chiefly to the treatnient of the lighter hydrocarbon products ot the petroleum group` con'iprehendcd in the tcrin gasoline, whether of Straight run7 yielded hy ordinary distillation methods, or of synthetic nature, produced hy high teur pcratnre and pressure, and hence, it will he 3o undcretooil that any cracked .stock having the lioiline points of gasoline, or the stock generally known as synthetic naphtha, or pressure distillate, is included in this dis: closure and is wit-hin the spirit of the .inven` tion.A

1t is recognized that certainstoclts or prode ucts of crude oil of the lighter grades contain sulfur con'ipounds` and .also constituents which forni resins and resii1 t1' .gu'rns. 4o This is particularly true of synthetic products falling within the boiling pointl range required for the Stock known as gasoline and producedvhy high temperatures and pressure, or merely hy high temperatures or by What A is' generally termed cracking The product resulting from the decomposition of" `petroleum oils hy high temperature and pressure or by merely high temperatures in a crude gasoline, and. 1s known 1n theart as crude synthetic iggasoline, and this invention is directed chie y to thev treatment of this crude *synthetic stock, though other hydroysuch 'as incssurc distillate above rel'er Serial No. 144,371.

cui-lions responding to the treatmentare ohviously included thereunder, such as crude naphtha or pressure distillate ahove relcrred to.

Since allsynthetic and sonic natural stool; contain sulfur and considerable gione and gum-forming and. other nndc .irahle constituents5 it is the object'. ol'l this invention to rcniove these compounds'or substances, and produce from a distillate containinginterior products a linished gasoline marketable as a first grade product. i

lt is a recognized fact that certain ginas and gum-forming compounds especially the di-oletines, although reactingr with sulfuric acid. are not removed hy it` as the product of `reaction is oil solubles.' There compounds are objectionable in a motor fuel or lamp oil. lVe have also found that although snll'uric acid and other reagents remore sonic sulfur,

-there exists a lpoint beyond 1which the removal of sulfur is no longer cliiectually removed by these agents. n

To eliminate 'the gum and giun-'forming constituents and to reduce the higlrsuli'ur contents ot' low boiling products and especially ot' a cracked or sour inotor iluelv or lamp oil, to within the limits generally specim tied for marketable products and to produce a. tirst grade fuel or lanip oil, ire "hare li-' covered the present' method` the details ot' which shall non' appear7 it. lia-ing undcrsmod thatjehang'cs inthe practice ot' the prmcss Sllll Vtlic aldepart'u'rc from the spirit oi the invention as expressed hcreinal er.

le prefer to usc for thisv 'prot a crude synthetic naphtlnu although a napiitha may he used that has a 'longer boiling' point d to; the crude gasoline in this spccilication we n ish to liai'c understood :i` un unrclined distillate haring' the proper luiilinfi` points for linishcd gasoline and resulting iront crackA ing `or treatment hy high temperature and pressure. This stock is usually treated with sulfuric acid, for purposes ot removal nl sonic, et thc undesirable compounds or constituents. While we prefer to start with said treated synthetic crude gasolinev We would have it understood that. our process is not limited to that practice, ndour invention consists generally in'hsmtn'g the lll) crude syhthetic naphtha with an alkaline solution., mixing the treated low boiling product with heavier liydrocarbonsy and then ilistilling the mixture, and specilieally our invention consists of the steps set out hereinafter, in the sequence in which they occur in an apparatus ofl the type shown. in connection with which the invention will now he described. v

Reference is made to the accompanying drawing which shows diagralnniatically the apparatusy which may be used t'or the process.

By means of a pump l, crude synthetic naphtha, treated in the usual manner with acid, is delivered from pipe line 2 to pipe line 3 into a mixer el, of ordinary battled' construction; and constituting substantiall agitators. This mixer Il is supplied witli once-used, relatively Weak alkaline solution, as caustic soda, through pipe line A5, by means of a pump G, to which the used alltaline agent supplied iroxn a tank 7, through line B. Alkaline solution, once used, as explained, is constantly supplied to the tank 7, as will appear presently. inthe mixer 4, a partial neutralization ot acid treated gasoline is ellected under normal temperatures,

that is, in the ahsence ot any supplied heat,

and such tenil'ieraturc may range troni 70 F. to 90o F., or he ot that degree resulting from storage conditions. Complete :neutralization of a cracked stock, after heavy acid treatment, is extremely dillicult in cold state, and hence the preliminary neutralization is resorted to to render the stock more .sensitive and susceptible to the subsequent treatment, hereinafter detailed, and to reduce the acid content, (Where such acid treatment precedes the present treatment), which requires further neutralization.. Since the alkaline agent does act upon any product in the oil which reacts acid, it will be understood that thealkaline solution used herein` is not confined to neutralizing acids, nor in, fai-t, to thc function ot neutralization.

From the mixer 4, theiniixtin'e of the crude synthetic naphtha and alkaline solution is passed through pipe line 9,=into a settling chamber l0, in which the caustic alkali settles out from the hydrocarbons and is drawn ollI through pipe ll, into a suitable tank l2.

'.lhe stock, being under a pressure above .atmospheric and preferably ot' from 3() to lf3() pounds, then passes through line 13, into :i heat exchanger 14, of any known type, infwliicli sonic ot' the heat of incoming treated hot gasoline, as explained hereinafter, is absorbed hy the cold, crude 'synthetic naphtha, passing through the exchanger let, in the exchanger 14, the temperature ol' Vthe mixture is raised to approximately 150G F. and, leaving the exchanger 14, through pipe .line l5, enters'a mixer 16.l

rlliis miser lil, is supplied with a large excess of relatively stron" alkaline solution from the supply tank 1f, through line 1S, pump 19, and line 20, and the fresh alkaline solution is intimately mixed with the naphtha. The mixture of naphtha and alkalinesolution is then Aforced through pipe 2l, into a steam or other heater 22, of any approved type, in which the mixture is further raised to a ,temperature which will produce the best results from and on the particular distillate undergoing treatment. The

heater 22 is supplied through pipe 22 with a heating medium, which is drawn olf through pipe 22..

In our experience, and for the most beneficial ellect and advantageous results, we lhave found that the temperature to which the mixture, to wit, the synthetic naphtlla and caustic is subjected should preferably not exceed 350C F. The temperature used is maintained on the mixture for a period of time which Willenable the alkaline solution to work uniformly and e-ectively upon the naphtha, in its heated condition, and thereby elect a thorough and complete neutralisation ot' the stock where it has been first acid treated. vWe consider this .hot alkaline treatment of the utmost importance in` o'btaining the satisfactory results which our experience proves, in removing undesirable compounds and especially sulfur and objectionable saltar combinations from the synthetic Acrude naphtha, Whether priorly acid treated or not. `We find also that this hot alkaline action upon the synthetic crude naphtha'operates to eliminate some of the gum-forming constituents .and to affect other gum-forming constituents in a manner to render them readily removable or extractahle by any available-means, as Aexplained later. `We would here have it understood again that this hot alkaline solution used herein is not limited to merely workinur a neutralization of an acid treated stock, Tint performs the other functions mentioned above; l i

'1n order to insure the most thorough neutralization of an acid treated stock' and to reduce to a minimum the sulfur andsulfur combinations, and also the gums and gumtorlning constituents prevalent in a. cgraked stock, we pass the mixture through pipe 23 into a mixer 24, and from the mixer 24, convey the mixture through ipe 25, through an injector 2G disposed in t e top of a drum or tank 27. By injection of the mixture in the drinn 27, the contact ot the hot alkaline solution with the hot gasoline is as nearly perfect as possible, with the result that the majority o the sulfur and nearly all of the gums and gum-forming constituents are broken down and are hence readily removable from the product as will appear later. It will he observed that the mixture of naphtha and alkaline solution, in order to llo maisv drocarbons and te execute the process in .t ie lliquid phase. The heavier portions of the yniixture settle on the bottoni of, and are forced out from the tank 20, through pipe 30, into the used alkaline solution Storage tank 7, While the lighter port-ion, which includes a mixture of gasoline and a Small percentage of the alkaline agent, is forced outl of the druin 29, through pipe line 31, into the bottom ofthe heat rexchanger 14, and from the top of the heat exchanger 14, through line 32, into a cooler 33. From the cooler'33, the mixture is forced through pipe line 34, into a tankf, a valve 36 being pi-ovided on the pipe 34, to regulate the pressure on the system, including the cooler 33, for the purpose of preventing vapor-ization. From the tank 35,?whatever Vsmall quantity of the heavier solution remains and precipi# taies may be drained oli' through valved plpe 36, to tank 37, from which the solution may be returned through line 38, to the used alkali tank 7, for reuse, as explained at the,

outset.

The treatment thus far described, of the crude synthetic iiaphtha with the caustic alkaline solution, under the temperature condition named, to wit, not exceeding 350 .l*`. and under a pressure above atmospheric` and siiliicient to prevent vaporizatioii or suhstantial vapor-ization, yields a product of straw color and lfood odor, but with the suitiur content not t iini'iiished to a satisfactory v low percentage. 1We have foundalso that Gli this hot treatment of crude synthetic naplitlia breaks down the gum-forming or resinous constituents, which are either held in solution or are cast down after'a period of time, as a viscous precipitate, without however' removing them. To reduce the suliir content to the lowest vpossible niini'inuiii,

4and render the treated stock -gnni free` we mix the treated gasoline with heavier hydrocarbons, preferably, though not necessarily, containing a percentage of gasoline and then subject the mixture to the' process of ordinary distillation. These heavier hydrocarbons, which include the crude petroleums, 'act as a solvent for the' natural gums and altered gums resulting from the liOti caustic or other alkaline treatment.' For the purposeof eecting a thorough mixture, thev treated gasoline is drawn. from the tank 35A. through pipe line 39, by pump 40. `andthe heavier hydrocarbons are drawn from thtl tank41 through pipe line 42 by pump 425. the pipes 30 and 42 being conjoined at A and the l two :fluids thus mixed forced through line 45 toa still not shown,

'e find that by tlie'subsequ'ent distillation of the mixture, the sulfur content of the resulting product is much lower than is the case where the separate stocks, to wi'tytlie Crude synthetic iniphtha-and the Istraighti'nn gasoline ai'e scparably produced and then mixed together.

W'e find also that the distillate resulting from the distillation of the mixture is sul4 stantially free from gum and gum-forming constituents which, as ex lained are extracted by the heavier hy rocaijbons, upon distillation with it, after having been ren dered extractable by the process as outlined.

The distillate obtained, We have found, re-

quires no other treatment than that usually applied to the straight-run stock, and we have found that the straight-run orf natural gasoline in the crude oil (if crude oil were used as the solvent), is mucbvi'm roved by the mixture and subsequent distil ation.

A specific example of results obtained by our process as above described and as being actually practiced by us follows:

VThe crude synthetic naphtha, having a sulfur content of 1.10%, was first acid treated .in the 'usual manner. The acid treated stock was then subjected to'treatment with la. caustic soda solution according to the method as disclosed in tliis'specification reducing the sulfur content to 0,54%.

This treated synthetic naphtlia' was mixed with a. crude oil of known gasoline content in such percentage that the resulting'combineu gasoline produced by subsequent distillation was composed of 77.7% straight run gasolinevand 22.3% synthetic gasoline b Y volume. The sulfur content of the finisher gasoline lio was0.07% and itwas practically free from y gunimyy residues.

On the other` hand, a mechanical niixtnri. (in the saine proportions as above) consist- -ing -of the treated Asviithetic 'naphtha and from 'the crude independently,l finishes with atsulfur the straight run gasoline distilled content of 0.22% and is otherwise .nii unde-V sirable product, containing a considerable amount of guinniy residue.

lrVhat We claim, is: 1.' The process of synthetic or cracke petroleum .products having the boiling points of .gasoline which consists in treating the products ,with a rela* tively weak alkaline' solution tov partially neutralize the products; in removing 'thel weak alkaline solution; in mixing. with the products thustreated'v a relativelyv strong alkaline solution and subjecting the mixture (purifying acid treated to a temperature not exceeding 350 F. while preventing substantial vaporlzation of the products,.to cause the relatively strong alkaline solution to.break down gums and gum forming bodies, in cooling the mixture, in separating the alkaline solution; in mixing the products .with a heavier hydrocarbon.,

relatively weak alkaline solution from the4 products; in mixing with the products a' relatively strong alkaline solution; in sub jecting the mixture to a temperature not exceeding 350 F. and to continuous agitatmn lo cause the relatively strong alkaline solution to break down thegums and gumjorming constituent,v in' maintaining a. pressure upon the mixture to prevent substantial vaporization, in separating the alkaline solution from the products, in mixing with the products a hydrocarbon heavier than the product treated, and in distilling the mixture to effect the removal of the gums and gum-forming bodies.

3. The process of purifying unrefined acid treated distillates having the proper boiling points for gasoline and resulting from cracking, which consists in ctl'cctiug a partial neutralization of the acid treated dis i tillates with a relatively weak alkaline solution, in the absence of any supplied heat; separating from the distillates then alkaline solution, then mixing with distillates a relatively strong alkaline solution and subjecting 'the mixture to. a temperature not exl'yecding 350 F. and agitating the mixture to break down the. gums and gum-forming constituents in the distillates, in separating the relatively strong alkaline solution 'from the distillates, cooling the distillates. mixing with the distillates a crude oil containing a known percentage o'f gasoline, and then distilling the mixture to cause the crude oil to remove fromthe distillates the gums and gum-forming products broken down byl the relatively strong hot alkaline solution.

4. The process of purifying acid treated products resulting from cracking which con sists. in mixing with the products a Weak alkaline solution and agitating the mixture to'elect a partial neutralization of thel acid treated products in the absence of any supplied heat; in separating the ,relativelyweak alkaline solution; in mixing the partially neutralized products with'a relatively strong alkali and subjecting the xnixture to a temperature not exceeding 350- F. and to constant agitation to break down gums and gum-forming'constituents, while preventing substantial vaporization; in separating vthe relatively strong alkalil` from the products; in cooling products; in mixing the products thus treated with crude oil having a per centage of gasoline, and in then Vdistilling the mixture to cause the crude oil to remove from the treated products,V the gums and gunnfornling constituents. 5. The process of purif ing aciil treated synthetic petroleum pro ucts having the boiling point of gasoline, which'consists in partially neutralizing the..acid treated prod -ucts and separatingthe neutralizing agent perature and pressure and for a period ot' sol llt)

y.treated gasoline by 'distillation to obtain :r

gasoline substantially free ot gum-forming constituents.

7. A process oi removing gum-forming constituents from cracked gasoline vwhich comprises heating a mixture ot' said-gasoline and alkali solution to an elevated temperature and pressure and for a period of time sutil/cient to convert said gu1n-forming constituents, separating the alkali solution from the gasoline and further purifying the thus treated gasoline by distillation to obtain a gasoline substantially free of gumforming i constituents.

8. A lprocess ol rcmoying gums'forming constituents from cracked gasoline `which comprises acid treating said gasoline. ncutralizing the acid treated gasoliiw,` heating a mixture of said neutralized gasoline and alkali solution under pressure to an elevated temperature and pressure and for a .riod of time suflcicnt to cause a, conversion of `said gum-forming constituents, separatin i the alkali solutions from.' the gasoline' an further purifyilur ythe separated gasolineby distillation to olitaiu a`gasoline substan tially free of the gu1n-forming constituents. In testimony -whereof we have set our hands.

.ioHN o. BLAoKi. wmT-D. RIAL. carnose r. HoWES.

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