US1991049A - Process for decolorizing oil - Google Patents

Description

Feb. 12, 1935. I s, E, CAMPBELL l 1,991,049

PROCESS FOR DECOLORIZING OIL Filed oct. 9, i929 rra/ener Patented Feb. '12, 193s M TED] STA-'ras PATENT .por-#Flea `N `This invention relatesto aprocess for Vdecolorizv ing `oils and is particularly applicableto? dis- `tillates derived from crudeoils,` suchaspetroleum,`

`rial`12, adapted topprovide large surfacevfor conshale oil, and the like, in the refining thereof.`v l '5 The principal=object1of the vinventionisto provide aprcess for decolorizingdistillates derived from the operation known `inr the artfastfcrack# ingtyand hereinafter referred to as Foraekd distillates, which distillates will remain stabilized as to color after being subjected to the process and i with minimum losses.` Y i "A further object isi-toprovideljaprocess in which a minimum quantity of acid is" made avail-` tillate. i y l A further object isto "providefa `process by which certain color forming compoundsand other yimpurities are continuously] removed from `dis`v tillates in" such formithatfthey` niaylbere'covered as by-lJroducts of` value. 'l

A further object is to provide a processby'which gasolineand/or-other distillates arev decolorized by the useof acid which is` continuously used until substantially exhausted "in" chemical reactions withthe distillates and/or impurities therein. Y

y In my co-pendingapplication SerialNo4349,606

filed `March 25,l1929 there" is disclosed a process in *which distillates are decoldrizedi `and thereby stabilized as V n orta dilute acid*solution,containing,"for instance,` less` than 93.19% "H2SO4, or less,H than concen-i tratedsulphuric acid of 66"1B;gravity.r f -By the use of weak acid;V through whichy thefdis tillateis passed, provides "for the absorptionby 35 chemical Vreaction of i Vvcolor r forming compounds contained in the `distillates, suchl' as nitrogenous The plurality of towers 11,' `11', `llff, andV 11" are-'connected in seriesV thrbughfvalve 27, pipe 14,' valve128, tower 11', valve 27', pipe 14', valve `28,;tower`11",Hvalv :27", pipe` 14'?, valve"28, towerfll' `and valve 27'f f, to discharge Ithe acid pipe minimally.. e Y y i The construction and-function o feach ofthe able' to 'decolorizeaA maximum lquantityl offdislv `29?y respectively `for n reaction productsto` a storagettank39 forgfurther 351i treated gasoline inacontinuous stream flow-into i y p 'Y t puritiestrst, whilein the last tower.1=1,"`thegacid i solution willjbe substantially fresh, the amount. 66,

towers :are alike` therefore a(v descriptionof towerll will` apply to'all. i l s Tower l1 is filled with acidv resistant inert matei tasting .the distillatmwith the acid,` and each '.55 tower is]y iilled.partially,` tofthe `line ,Xe-X; with i a'dilute acidisolutiorr throughupip'e 13and-valves1l 3,7, 373.37,l and37", which-acid solution is initially `supplied vfrom an exterior source through a valvelw- L f The acidsolution 'may` be any dilute lacid solution, but preferably a dilute sulphuric acid solu` L I tion' is used as one, .-forinstance, less than 1931.9%v H2SO4, orv about 50% H2804. Thestrengthof-the dilute-acid solution,however,` willlvarywiththe 15%* j, nature ,of` thehydrocarbonfdistillate under .treatl u ment; tofobtain. theidesired results.l l l ,Pipelis divided at' a valve to direct'the distillate on one side to a valve 33 and agbyepa'ss jmanifold 32A connectedto towers-11; 11"11'a'nd spectively, and on the other side of -valve 34is a I n l withdrawal by-pass manifold 35vwhich: connects theipipe 15 withextensions ,ofgpipesf 14,314" and"` 14,1fthrou`ghyalves 31, V31',l and 31f;respectively." 2`5`v -Theqobject'ofthe Icy-passing `ofizthe stream `how of distillate around valve 34 4isitobe able tosuby ject the'` distillate to acid treatment-in the plural'- ity of towersin rotationso-that the `acid'inpeachr tower is substantially exhausted,I as will Vbe further" 301` treatments.

Byfcontinuously flowing Vafstrearn yof1 from pipe 10 `'throught ,the lacid' towersand con- -V nectionsas;described, t0 pipe 15, (valves26f,2635",I

a 'dilute 'acidsolution 'jin` `'series relation; to vthe end that the color forming compounds fconpris-l,` ing nitrogenous bases, such as pyridine, quinoline, 41;1 andthe like, and/or otherbasicimpurities, in the distillate-1 `are labsorbedfin decreasing amountsfin each tower in proportion astliestream is denuded I 'l ofsuchcomponds: l I Y. i I'he denudation of the'basic impurities in'the l50f distillate'lstream by `such flow Gin series causes the dilute acid solution in tower 11 to become sub`- j.

stantiallyiexhausted by reactionfwith such imand strengthvof acid in` each tower being regulat- V ed to this end.

Upon the substantially complete saturationV with impurities of the acid in tower 11, valves 26, 27, and 28 are closed and valve 26 is opened to maintain the stream flow through the remaining towers 11', 1l, and 11" serially.

` vValve 29 is now opened to Withdraw the eX- hausted acid and reaction products through pipe 38 to tank 39, whereupon valve 29 is closed and valve 37 opened to rell tower 11 with fresh dilute acid solution.

, Valves 37 and 34 are then closed and valves' 33, 30, 27 and 31 opened, whereby towerv 11 becomes the last in the series and tower 11 the first `in the series.

, In this manner the plurality oitowers are used in rotation to always provide that the stream of cracked distillate shall be subject first to apartially spent acid solution, and last to a substantially fresh acid solution, whereby: substantially all color forming and other basicv impurities are i removed byv such treatment.

Not only doesosuchtreatment with a dilute acid solution insure the removalof the desired impurities, but such is in strongcontrast to known treatments-of distillates for the v.removal of such impurities by the use of concentrated acid, in

whichthere may be as much as'80% of theoriginal concentrated acid drawn 01T in the acid sludge with the impurities and which is generally a total loss.

The dilute acid is substantially completely rused up and the reaction products are in the form from which by-pro'ducts of value may be recovered. The stream ofdistillate thus treated `with dilute Y acid solution is conveyed" through pipe 15 to a settlingl tank 16, from which any. acid carried over is'removed through a pipe 17, the rate of throughput'being so regulated that a minimum quantity of weak acid isthus carried over.

From'tank 16 the vdistillate passes through a pipe `18 and valve 40 to an alkaliv tower v19 which previously beenparti'ally lled to the line Y--Yy with .a relatively strong alkaline `-solution, for.v example, asolution offcaustic soda, .valves-43 and 49'being closed.

Such solution may be, for instance, a' solution containing 30%vr of sodium hydroxide, or other equivalent alkali, which absorbs the acidic impurities in the acid treated distillate with 'avidity, t'c'the' end that the solutionv absorbs "about an equal volume ofVV acidic impurities, or more,4v depending `o'n the 'nature of the hydrocarbonmaterialfoeing treated, before becoming exhausted. Weaker solutions may be used, as well as solutions of 'potassium hydroxide, orsodium plumbite, but-a strong alkaline solution is advantageous to 'coniine the alkaline treatment to va'single'passage through the alkaline solution, whereby themanimumamount 'of acidic impurities maybe con-` centrated thereinin comparativelysmall volume y j and less frequentrenewal of thealkaline solutionrwill be required. Y A V:.l-Ifowever, forconvenience, two or more towers 19.3and 19. areprovided series, primarily.' to maintain continuous operation and secondly if. it is` desired to use dilutealkalisolutions. In the latter case, a plurality of alkali towersmay be arranged in s'eriesrrelation to be used'in rotation as already described for the'dilute acid towers.-f`

Tower- 19t mayjthus `be connected vthrough pipe 21,gand1valves 1-41-and40f j to tower 19'., likewise Prtlyilled with; caustic ksoda 'solution'x the'diswhereupon tillate passing thence through pipe 42 and valve 41 to a settling tank 22, from which any alkaline compounds carried over may be withdrawn through a pipe 43.

Thus, in operation, the acid treated distillate is passed through a plurality of towers containing relatively strong caustic soda solutions, in the first of which substantially all impurities of an acid nature are absorbed, the second tower, in the use of strong alkali,merely assuring that no acidic compounds remain in the distillate.

The passage of distillate through tower 19 continues until the caustic soda therein becomes substantially completely exhausted byreaction with acidic impurities, which include such compounds as phenols, cresols, and the like, and/or organic compounds such as naphthenic acids and the like,

tinued by closing valves 40 and 41 and opening valve 43.

The caustic 4solution in` tower |19 being substantially'iresh, insures the continuous removal of acidic impurities as previously Adescribed for tower 19. i c Y. w

Valve n44 is -now opened and the Vexhausted caustic solution and reaction products lare re,-V moved therethrough to line 45 and storage tank 46whence they may be withdrawnth'rough pipe 47 andthe acidic impurities recovered asy byproducts of value in many ways;

Valve 44 is now closed and valve 48j opened` to partly refill tower 19with freshgcaustic solution through a supply pipe 20l torbe lready for use upon exhaustion of the caustic solution in Vtower 19', at which time valves 43, 40,' and 41fare closed and valves V40, 41, and a valve49 in; a bypass line 50 are opened, to permit the recharging lof tower- 19,7l with fresh alkali solution.`

By thestepsgofV the processthus described, the selective treatment of a stream` of Ydistillate is provided to --rstremove basic impurities,and then remove acidic impurities, in avcontinuous manner in which the Vacid and alkali used'are substantially completely exhausted, the vvfreaction productsand color kforming compounds being recoverable as 'by-products of value, p

f The nitrogenousbases and otherbasic impurities removed by the dilute acid treatment and collectedin tank 39 mayberejcoveredby ya` treatment such as` is described in United States vPatent No.y 1,686,136,the strengthof the dilute acidisolutions employed being such` as to convert the basic compounds Yinto l sulphates .without material polymerization, or Vwithout reacting materially on acidic impurities tochange, or possiblyidestroy; such asy are desired to` be collected inv the, alkali treatment for recovery asproducts of value.

Such change, or destruction, may `be ,accom-l plished by the use of concentrated-acid;in towers such as'gasoline. J n Y The distillate, after acidand` alkali treatments,

in settling tank 22 mayL still contain' certain other` unsaturated and gum formingconstituents which cause turbidity andV affect they'desired brilliance of thernishedvr distillate.

The partially treated racked y:distillate therefore transferred throughfa, .pipe 51 and valve 52 toan inlet pipe lacontrolled by a valve` the stream flow of distillates is con- `tation .whereby.:thecgdistillatef` is.` rst `contacted concentrated sulphuric` acid inthe neighborhood of 66..B. gravity andy-inasmuch `asithe .modelzof l' operation of the concentrated acid towerseisf-likei and alkali `treatments of cracked 'distillate there are .1arge` losses in acid and in products.,comet` prising Valuable ,gasoline `fractions 'y whichjhave been polymerized land further thecoloriofsuch che with partially spentyconcentrated. acidK and last,- .y ly .i withV substantially fresh l strongA acid to the end .that all-the strong) acid .isi substantially .sat-

uratediwith impurities, on exhausted. The tconcentrated` .acid preferably, used 'sisma that already described-for: the ydilute acid towers,

a .descriptionY of such "involves needless 'repeti i tion `to one skilledin the artt .1

However, the functionof the `concentrated treatment and ,the resultsachieved thereby .cornprise animportant step in my process;

L ,While concentratedacid decolorizes a. cracked distillate to :the required icolor,v *in ordinary acid treated :cracked distillate does not? remain,` stable. Likewise,v ,ont treatinga V'distillate primarily withA concentratedacid, the y oxidizing andgcther ceptible of easy recovery.

Presumably; also; certain of thejriysr'ocapoi compounds jare loxidizedby concentrated acid treatment, forming "complex reactionl mixtures, and fare withdrawn inl the body of the partly ex`" hausted concentrated acid, .thereasonfforthi's being the effect of4 the .heat of reaction resulte. ingfrom;theimixture,ofrconcentrated acid and y crackeddistillate...

The furtherobjects of my `1ir'1`vi`ention bythe succeeding enumerated steps include the treatment `oi? cracked hydrocarbon with a dilute; acid ina plurality of treatments whereby `the dilute acid is substantially exhausted,` the recovery of by-products from the exhausted 'dilute acid, the

thenfurther'treatment of the cracked hydrocarbons with a concentrated acid vin a plurality of y treatments whereby the concentrated acid is substantially exhaustedand the loss of concentrated acid and polymerized Valuable fractions is minif late is mized, the treatment of the exhausted 4concentrated acid to recover valuable by-productsand a dilute acid suitable forthe initial steps of the process, `tlie final decolorizationof the cracked distillate to acolor of 30+ on the Saybolt color-` ,imeten and the stabilization cracked distillate.

To these ends the partially decolorized passed by pipes 51A and 10a ,through the 11a, 11b, llc, and 11d, having respective towers temperature control coils, or Jackets, 67, 68, `69,

f and 70,..wherein it is subjected to the actionof Lio " other suitablefmeans concentrated acid, whereby it is nally cleared of certain remainingv chromogenic and unstable substances to f gain` its `colorV and brilliancy and l 'whereby f certain hydrocarbon sulphatesr are` `formed by the, chemical action ofthe concen-v "trated acid.

r ylllponexhaustion ofthe `concentrated'acid in any of the'towers 11a, 1lb, 11c,`and"11d,"the reaction `products are withdrawn through line 38a 'i toa ystorage tank` 39a. The treatedA distillate passes through pipe 15a to a settling tank y16a or calu eifects thereof may changeQthe "basic, impnritie'sinto 'compounds `which arettoo, .corne ple'XQtfo recover. in appreciable q'antitie's,T,inas``A of the color of ,the`

, l `of Iseparating acid and disey i tillate, whence any concentrated acid carried over is `withdrawn througha .pipe 17a.` y 0.337%to 0.042%.

Fiom sealing tank .nieu the distillate passes `thronghapipellfidtoneutralizingztanks21917, and l 19b1contaming a suitable. aikanne soiutioniofA sufficient .strength .top take care` of any acidity. in the .distillate e and thence throught `a.fpipe- 42a1.to

awash tank 56to which water is suppliedthrou'gh a line `5'47,.whereby any alkali is-.removedandwith;J

`1 The distillatew thus :purifiecLLidecolorized,`

brilliant`,1.aftenzremoval of iwaten' xpasses. from thence to storageorlotheruses; i.

` .4 ."rheexnausted ,alkaiimay .be wiihdrawiiff'roi either; of thetowers 19a;org19bthrough;a `line 45a Lto ,a i storage.. taiil'syla,v from'lwhichtankfit maybe taken, through a `pipe 47a for any desired vWhilejthese novelresults are obtained; it must notbeoverlooke'd;thatjthewastaof.strong acid; "L

as` normally fused, is `substantially eliminated;v

aswell :itstheloss, of;polymerizedwaluableframej The'processasdescribed is adaptableltofandise tillate `obtainedfromv cracking a straight Iun' gas oil,` a cracked `gas oi1, -a,v crackedgffuel oil, orma. cracked kerosene, 1variations.A in.: the strength :of the acid used being. permissible# iii-accordance `with.tl1eY characteristics of fthe Ndistillate being treatedj The` effective results of the strong acidtreat--` ment on arcrackedfydistillateare due tothetexn-A f perature4 controls exercised` byithe coils 67;. 68, 69; and 10` which conveyga cooling,- or- -refrigerating,`

is effective Aperature vbycarryingaway theexothermic lheat fio of polymerized valuable fractions is minimized.

- The temperaturey to which the cracked' distillate in towers 11a,` 11b,111c, and 11d is reduced and vheld should preferably be` below 32 F.`

The process herein describedisfof course, ap-

plicable to mixtures of straight run distillate with f cracked` distillate, the concentrated acid treat# mentv serving not only to remove chromogenic bodies, but also unsaturated andgum forming` compounds. i

`In this respect the term substantiallyexhausted as applied toconcentrated acid, initially of v.from about to 93.19% H2504, may include n any degree of exhaustion by reaction down to the "point Where the acid properties 'of the mixture `frorntank 39aiszero. l

yThe degree of exhaustion of the vconcentrated acid will, however, be somewhat governed by the i type of compoundsremovable by reaction theref" witln it being readily understood-that a con-f centrated acid, as such, may be substantially ex- In general, (however, the concentrated acid used in treating the cracked distillate will be re vduced toabout 20% acid or less, which of hausted when its strength hasl been reduced to .u

course, recovered from the treatment in tank 61 l and used as make-up'weak acid supplied to the tillatef ForV instance, sulphur.` content of weakacid towers 11, 11', 11"., and'11",and` the concentrated acid treatment is found to materially reduce the sulphur content of the dis- `Iihavethus ireduced'the J a crackedfdistillate from l@ washitank 56 throughqline 59 to a=lteri66a `and l [prises: continuously passing'a streamfo-ffcracked hydrocarbon. distillate V'upwardly in succession t t. y naar a -I inventionz'. f7? t f it 1; 'A .process ,'for decolorizing oils which coni# through av plurality `of zones.' containing 'pools Vof dilute sulphuric acid 'of azstrengtl suiiicient to reiiove Vthe bas-icimpuritiesvin the distillate but insufficient to remove unsaturated. hydrocarbons and until the. dilute. acidis. 'substantially exhausted A'successively in each zone,V 'passing Athe stream out of zthe `last Zone .through a mass-.of contact material to provide that substantially no free acidsolution isicarried from said Zone with said streamfthen passing said stream through chf-alkaline 'solution whereby the acidic impurities linthe distillate areremovedthen subjecting the stream to an extended passage through 'zones containing pools offconcentrated.sulphuric Aacid ata flow `temperature vwherebyasaid `'concentrated'acid substantially exhaustedv in r'each y zone? inlsucc'ession, :then through an alkaline soluN alkaline solution whereby the-"acidic impurities in the distillate areremoved, then subjectingfth 4stream 'to lan .extended passagethrough "zones l containing; lpools of concentrated sulphuric .acid

at a-loW temperature Whereby'said' concentrated acid substantially exhausted in'eachzonet'in succession, thenthrough anlalkaline solution', re' covering the exhausted concentrated acid from eachof saidv Zones' and treatingi'said exhausted concentrated .acid 'to recover Vsaid vdilute :acid therefrom. j t l L .1.1

o z3.` A process for decolorizingoils which comprises: continuously passing a stream ofcracked hydrocarbon distillate upwardly in `'succession through a plurality of zone `containingpoolsof clilutesulphuricv acid ofa strength sufficient to remove the basic impurities in the distillatebutv is suli'cientlto remove unsaturated hydrocarbons and until the dilute acid is substantially ex'- hausted-successively ineach zoneppassing the stream out of the last zone through a'massfof contact material to provide that substantially no ireefacid solution is carried from said zone 4with `said stream, then passingsaid stream "through analkalineV solution whereby the acidic impurities inthe distillate are removed, then 4subjecting the stream to an extended passage'through zones containing pools of concentrated 'sulphuric 'acid at a low temperature Wher'ebysaid vc'ifoncen-V trated acid is substantially exhausted each zone in succession, thenthrough an alkaline solu@ tion, recovering the exhaustedconcentrated acid from each oi' said zones, treating said exhausted concentrated acid to recover a dilute acid therefrom, and returning such dilute acid to saiddilute acid zones. l

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