US2006407A - Process of preparing stock for distillation of lubricating oil - Google Patents

Description

July 2, 1935. A. E. PEw, JR

PROCESS `OIF PREPARING STOCK FORDISTILLATION OF LUBRICTING OIL Filed July 29, 1952 Patented July 2, 1935 UNITED STA-Tas ration of New IJersey ,Application'July 29, 1932, fserialnafczegose J The present invention` relates toajprocess for chemically treating topped crude oil to prepare it for distillation `into its various lubricating fractions. s e

In the distillation of lubricating oils from topped crude oil it is of the utmost importance to free the stock charged to the lubricating oil still from any impurities which may be therein contained and which are the results of cracking or oxidizing a portion of the crude while topping the same.

'Such cracked' or oxidized compounds, -if permitted to remain inthe charging stock, willultimately Vaporize with the lubricating oil fractions during distillation,l thereby making such lubricating oils t unfit for sale without extensive chemical treatment, as, the crackedpor oxidized compounds greatly impair the color, odor., etc., ofthe-dis-V tilledoil. It is,v also vof the greatest importance to remove any water, whethery naturally present in the crude or added thereto inv processes for 'treating it to prepare it for distillation. l v As some crudes are received 4from thewells they contain, among other impurities, sodium, magnesium, and other chlorides. Some of these u chlorides `are removed in solution when the water originally containedin kthe crude is settled out, but a small propo-rtion of them will remain in the crude.l When the toppedHcrude/is subsequently treated with alkali solution to remove cracked and oxidation products, the alkali used is a commercial form containing impurities'in the form of chlorides.` ,If the toppedcrude is not thoroughly dehydrated after the alkali treatment, serious harm is likely to'result, *as the Water-tochlorides react, at the temperatures requiredl to fdistill lubricating oils, to form hydrochloric acid. This acid is extremely corrosive to the metal of the stills and for this reason all water must be removed, for without it the chlorides cannot form hydrochloric acid and rhave no deleterious action on the stills. It is necessary to treat the topped crude with an aqueous solution of alkali in order to get a complete mixture and contact between 'f the oil and alkali. If alkali in solid or lfeoinminuted form is addedto the oil,-a complete mixturecannot be effectedand the alkalisettles out `onto the heating surfaces or" thestills, ythereby-in a short time impairing heat'exchangeto such an gether with the naturally 4, present and` added Y rected. more 'speciilcally.y to A)an improved method for treating the topped `crude with sodium hydrox-l ide or other alkali solution; u

" An lobj-ect l of", the: `present .invention j is to 'Spro-v -videfa processifor treating the toppedcrude lor mazoct by. `thoroughly 'mix-ing `th'e same with'fs dium hydroxide' solution to -convert 'some ofthe cracked or oxidation .products present intol complexfmgh :boi-1mg compounds, `mainly soaps, which Willnot vvaporize atf'sub'sequent `distillation temperatures'fand'to 'precipitate other cracked `or oxidation productsfas sodium salts.`

Another., object- `is,. toy remove. watery which? is introducedas afs'olvent for the .sodiumhydioxide',` from 'i the fmazoot:7 beforey distillation. ofl the lcontained lubrcating'ifractions. v Affurther. object istofremo-ve from the alkali treated crude" all decomposition products which are-precipitated icyh the alkali treatment and sub sequent dehydration; r y -.'Ihe process" setforth herein kmay be carried out nxanyzsuitable apparatus'but- I have found that .the lspecic apparatus .shown herein 'gives the-,bestresults.V i

l"In thedrawing':

- Fig: 1 is 5a front elevation withia section ofthe tower. cut away; y v''1gz`2 a v'section'of Fig-f1 S'v f f v Theheated topped crude or mazoct is continuously pumped to the mixing and-evaporating tower'throughlinei: The crude, owliich this' mazoot is a: residuum, is rst subjected to treatmentanddistillation'as described in said Pew Patent No. 11,833,691# that is, it isrst freed of its 'contained salt water.- by. heating and settlingv under 1 pressureafter-` which it is: further heated m-apipesuu, and the lighter constitu`V ents,such ,asA gasoline, kerosene, and gas oil, vaporizedin a distillation'tower'. y The bottoms from thisudistillat-ion tower, which comprise-the mazoot to be treated y by g-the' ypresent invention, leave-'the "distillation towerand are pumped Vto the .apparatus herein described ata temperature of 5009 to 5'75. F.

The heated-mazoot continuously enters the mixing pan 4'in-,tower 3, tangentially thereoLiso as 'to give it a whirling motion and is therein' mixed,ffor example, with v1% of 38 B. sodium hydroxide so1ution, which'is pumped through linev 2 andyjforced downwardlyfinto .the whirling mazooft. As the mazoot-soda mixture overflows the *tower on line 2 2 of to preparey the. crude 'oil with the water. Due to the high temperature of the mazoot (500-575 FJ, the tower 3 nay be maintained under a pressure above or below at; .A mospheric or may be maintained at atmospheric* pressure. However, since it is usually desired to evaporate .as much of the water (soda solvent) and as little oil as possible in the tower, the best working pressure can be determinedfrom these factors. The water and oil vapors pass upwardly through the tower 3 and then through line 8 to a condenser and separator (not shown) f. l Safety valve 9 is provided at the top of the tower to prevent the pressure from rising above any predetermined point.

TheV soda-treated mazoot passes. downwardly from the bottom of the tower through throatlll to one end of a settling chamber through which it flows to the opposite end whence it passes through cross-over line I2 to one. endof settling chamber I3. Atthe opposite end, settling chamber I3 is 'connected toa third settling chamber I5 by cross-over I4. .After' flowing through lchamber I5 ythe treated mazoot passes outof the system through vline I6. Vapors are formed within the'three .settling tanks which, if permitted to accumulatewithin the tanks, would by their pressure lowenthe level of the liquid within the tanks jtoa point below c the cross-overlines I2 and I4, thereby preventing equalizing line 2| by pipes I9/ and 2|| respectively.

Any difference in pressure within the three tanks is. equalized by the line 2|. Connections` 22fand 23 are placed between line 2| and vapor line,24, which conveys any vapors generated within the tanks to the top ofthe tower 3. 'I'he provision of vapor line 24 obviates the necessityof the vapor passing into the throat between tower/3l and tank yand then up against the downwardly flowing soda treated mazoot. At times the settling mazoot may foam due to thefrapid forma-I tion of vapors in the. settling tanks, in'whi'ch case the foam passes over pipe 2| to the throat between tower 3 and tank :and isfbeatendown by-the fallingmazoot. 1 i

, During the passage of the soda treated mazoot through the settling tanks II, I3 andc|5 certain sodium salts, formed by the action of the caustic soda on the cracked and oxidationV compounds present inthe topped crude, are precipitated. These sodium salts settle to the bottoms of the tanks and are drawn off at' intervals through valved outlets 25, 26 and 21, .atthe'center of the' respective tanks. Each of these outlets is` connected` to a manifold 28, which in turn is con-'- nected to pump 40 by line 39. These sodium compounds are of such a nature that they" are liable to pack solidly in the bottoms of the tanks II, I3 and I5 and thereby stop up'the outlets 25, 26 and 2'I. For this reason there are provided two other draw-oil.V pipes in each tank, one draw-off being positioned'at each end of the tank. 'I'hese draw-offsA entend downwardly from near .the top of the tankto within a `few inches of the bottom so that there is no 'likelihood of their .being stopped up by tightly'packed sludge.

`42 jto'regulate the outflow of sludge. Vdraw-offs are located directly to the rear of the 'I'he draw-offs just described, ywhich are placed in the front of the settling tanks, are numbered 29, 3| and 33. vDraw- offs 29 and 3| are connected to pipe 4|, which is provided with valves for controlling the flow from each tank. Pipe 4| is connected to pump 40 by lines 35, 31 and 39. The front draw-off 33 in tank I5 is connected to pump 40 by lines 42, 43, 35, 3T and 39. This draw-01T is also provided with a valve in line The rear front draw-offs and are numbered 30, 32 and 34. These draw-offs are also provided with control valves and connectingflines to pump 40. Line `36 corresponds to line 35 in the front draw-ofi system andA connects through lines 3l and 39 to pump 40 while lines 45 and 46 correspond to lines 42 and 43 inthe front of the tank. It is readily seen that with the arrangement just described, any one sludge draw-01T may be used if -morefsludgevshould collect in any one tank than in the others, or all sludge draw-offs may be used at once.- 4

By the foregoing process, the oil is thoroughly dehydrated, thereby preventing' the formation of hydrochloric acid, the destructive effects of which have been hereinbefore explained. l

A It has been specified, herein, by way of an example, that 1% of 38 B. caustic soda solution is admixed with the mazoot. The necessary amountof 'the soda, however, varies with dif-A ferent crudes. The caustic soda is not added to treat the maz'oot solely infthestep of preparev ing mazoot for distillation into lubricating oils herein described, but is also added so that there will lbe a surplus-of free alkali left in the oil to react with any cracked or oxidation compounds which may form during the actual distillation. For' this reason enough caustic soda is added, in the process herein described, so that about .2% of free alkali remains in the asphalt bottoms after the lubricating fractions havebeen removed or distilled off. I therefore do not wish to be limitedto-the addition of 1% of 38 B.' caustic soda, since the desirable percentage and degree -of `concentration are variable factors. The free alkali left in the topped crude is so finely divided, dueto the intimate mixture possible when it is added in aqueous solution, that it will not settle out onto the heating surfaces of the stills.

It-is ordinarily desirable, in tower 3, to vapori'zev only the solvent (water) of the alkali. However, some light oil fractions are likely to evaporate with the water; and it may be desirable,`under some conditions, to vaporize in the tower,` in addition to the water, an intermediate or fl'nal'cut of gas oil or a light fraction of lubricating oil. This can be done without departure from the invention.

The apparatus herein disclosed for carrying outl theV described process is not herein claimed, the same forming the subject-matter of a divisional application filed June 27, 1933, Serial No.

677,798. Having now fully described my invention, what I claim and desire to protect by Letters Patent is:

`1.',The processof preparing stock for distilla-l tion of lubricating oils, which comprises distilling from crude petroleum oil low boiling constituents at a temperature approximating but below that at which substantial cracking occurs and thereby separating a residual oil containing the lubricating fractions which it is desired to subsequently distil, continuously flowing a stream of the hot 2;O"o6,`4o7 l `precipitate impurities contained therein flowing oilglevaporation of solventi' continuously flowing the dehydrated oil to a zone of a'settlement'and thereinsettling' outA` sludge, and withdrawing precipitated sludge from the bottom of the settling zone and from a level above the bottom Y of the settling zone.

l residual oil tangentially,

2. The process of preparing stock for distillation of lubricating oils, which comprises distilling from crude petroleum oil low boiling constituents at a temperature approximating but below that at which substantial cracking occurs and thereby separating a residual oil containing the lubricating fractions which it is desired to subsequently distil, continuously flowing a stream of the hot residual oil, and'also a stream of an alkali solution, into a mixing and dehydrating zone and therein both mixing .the same and` distributing the mixture lover a large area under such absolute pressure as to effect, at the temperature of the oil, evaporation of solvent, continuously flowing the oil from the tower to a Zone of settlement and therein settling out sludge, and removing from the zone of settlement substantially dehydrated and sludge-free oil containing free alkali.

3. 'I'he process of preparing stock for distillation of lubricating oil, which comprises distilling from crude petroleum oil low boiling constituents at a temperature approximating but below that -at which substantial cracking occurs and thereby separating a residual oil containing the lubricating fractions which it is desired to subsequently distil, continuously ilowing a stream of the hot and simultaneously flowing an alkali solution, into a pool of a mixture of oil and alkali solution, whereby the oil and alkali solution are intimately mixed, overflowing the mixture from the pool and at a lower level distributing the oil over large areas under such absolute pressure as to effect evaporation of solvent, and continuously removing residual oil containing free alkali. l

4. A process for preparing heated topped crude oil for distillation into its contained lubricating fractions comprising distilling from crude petroleum oil low boiling constituents at a temperature approximating but below that at which substantial cracking occurs and thereby separating a residual oil containing the lubricating fractionsv which it is desired to subsequently distil, mixing a flowing stream of alkali solution with a flowing stream of said hot residual oil and evaporating solvent of the alkali therefrom by the contained heat of the oil; then passing the alkali treated oil to a settling zone wherein impurities precipitated by the alkali are settled out and further vaporization of alkali solvent takes place, andv separately removing settled impurities, vaporized solvent and treatedv oil.

5. A continuous process for preparing heated topped crude oil for distillation into its contained lubricating fractions comprising distilling from crude petroleum oil low boiling constituents at a temperature approximating but below that at which substantial cracking occurs and thereby separating a residual oil containing the lubricating fractions which it is desired to subsequently ,distil, flowing such residual oil into a mixing zone; conveying alkali solutio-n into said mixingv zone and intimately mixing it with said oil to the Yalkali treatedfoilfrom said :mixing zonev to' a settling `zone .and evaporating and removing *y solventyof "the alkali,` while yso ilowing, by .the icon*- taineclxheat ofthe oilg" the oil'flowing. through f said'fsettlirig zone-:at la greatly reduced. speed and n; therein f settling;V alkali precipitated impurities ;v fand. lcontinuously Y and separately removing evaporated solvent of the alkali and alkalitreated and settled oil from said settling zone.` Y

6. A continuous process for preparing heated topped crude oil for distillation into its contained lubricating fractions comprising distilling from` .crude petroleum oil low boiling constituents ata temperature. approximating but below that at which substantial cracking occurs and thereby separating a residual oil containing the lubricat-r ing fractions which 'it is desired to subsequently distil, flowing such residual oil into a mixing zone;

-leased therefrom.

7. The process of preparing stockv for distillation of lubricating oils, which comprises distilling from crude petroleum oil low boiling constituents ata temperature approximating but below that at which substantial cracking occurs and thereby separating therefrom a residual oil containing the lubricating fractions which it is desired to subsequently distil, continuously flowing a stream of the hot residual oil, together with an alkali solution, into a zone of mixing and evaporation and therein mixing the same and distributing the mixture overa large area under such absolute pressure as to effect, .at the temperature of the oil,evaporation of solvent, continuously flowing the dehydrated oil to a zone of ksettlement and therein settling out sludge, vwithdrawing sludgefree oil from the zone of settlement, and conveying vapors from the zone of settlement to the zoneof mixing and evaporation.

8. A continuous process for preparing heated y topped crude oil for distillation into its contained lubricating fractions comprising distilling from crude petroleum oillow boiling constituents at a temperature approximating but below that at which substantial cracking occurs' and thereby separating a residual oil containing the lubricating fractions which itis desired to subsequently `distil, intimately mixing with such residual oil an alkali solution adapted to precipitate impurities contained in the oil; then flowing said oil and alkali mixture in a` dispersed state to vaporize solvent of thealkali by the contained heat of the oil, and removing the evolved solvent vapors; then passing the alkali-treated oil to a series of settling zones wherein impuritiesprecipitated by the alkali are settled out and more alkali solvent vaporizes; removing the solvent vapors from each of said settling zones and equalizing the vapor pressures on said settling zones; removing settled impurities from said settling zones; and continuonsly removing dehydrated, alkalitreated oil from the final settling Zone.

9. The process of preparing stock for distillation into its contained lubricating fractions comprising' distilling from crude petroleum low boiling constituents at a temperature approximating butbelowthat .at which substantial cracking occurs, mixing alkali solution with the residual oil, and evaporating therefrom solvent of the alkali by the contained heat of the oil in a. plurality of zones in the first of which the oil is distributed continuously removing alkali-treated and settled oilfrom the second zone and alkali solvent vapors from both zones.

n. n ARTH. E. PEW, JR.

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