US1833691A - Process for preparing crude oil for distillation into lubricating oils - Google Patents

Description

NOV. 24, 1931. A E PEW, JR

PROCESS FOR PREPARING CRUDE OIL FOR DISTILLATION INTO LUBRCATING OILS W pw Q\ N YN ..U\ w i y W r u e, QS/ MN um ww wm, r MIMT RS@ l|Y f www/w, m lv ww @A Mw Q Av. a f Q, .T wf/ vw Nw All Alm w f W Nov. 24, 1931.

A. E. PEW, JR

PROCESS FOR PREPARING CRUDE OIL FOR DISTILLATION INTO LUBRICATING OILS Filed Dec. ,'22, 1926 2 Sheets-Sheet 2 Patented New. 24, 1931- aan ARTHUR E.- PEW,3JR., OF IBRYN MAWR, PENNSYLVANIA, ASVSIGNOB .T SUN OIL COM- PANY, OF PHILADELPHILA,PENNSYLVANIA5 A CORPORATION' 0F NEW JERSEY PRDCESS FR PREPG- CBUDE OIL FOR DISTILLATION INTO LUBRIGATIDTG OILS Application led December 22. 1926. Serial No. 156,287.

Theobject of this invention is to remove A from crude oil' its lighter fractions, principally gasoline and gas oil, in such manner as to adapt it for distillation into lubricating oils of the highest grade. `A more specilic object of vthe invention is to' so top and otherwise treat crude oil that subsequent redistillation of the residual oil will not yield a fraction 4having a viscosity of less than 100 seconds 1o Saybolt at 100 F. when such fraction is sub- -stantially more than three per cent; of the toppedl crude. Another'object of the invention is to contribute to the accomplishment 'of the general object above mentioned by avoidance ofcracking (this being essential to p a subsequent maximumpyield of high viscosity lubricating oils) andby avoidance of' oxidation (this being necessary to the production of lubricating oils of good colors) The objects are accomplished by the withlin process, which is characterized by topping at high velocities withv short time intervals a and at comparatively low temperatures (essential-to avoidance of cracking) and under `-,conditions that excludev the contact of air with the hotfoil atany stage of the process; with such efficient fractionation and regulation and control of temperatures and pressures as enables the subsequent production. by distillation underproper conditions, of lubricating oils of high viscosities.

The within process is actually a part of a complete process of producing lubricating oils as set forth in an application filed January 8` 1927, Serial No. 159,754, which matured into Patent No. 1,761,153, on June 3,

1930; the production of lubricating oils of the very Vhighest grade involving not merely` novel features in the @process of distilling the lubricating fractions, but also such pre-treatment and distillation of the crude oil as will provide a residual oil that is in the condition required for carrying on the lubricating oil vdistillation process. The complete process. as well as that part of the process which involves the distillation of the lubricating fractions, is

claimcd'in s aid application; the present application being directed to only that part of ,the complete process which involves the topping vand treatment of the crude oil preparatory to the production of lubricating oil.

t will, therefore, be understood that a1- though. the process herein claimed is adapted to the production of topped gasoline of high quality, the process is lnot primarily concerned with the production of asoline or gas oil but withltheir separation om the crude oil in such manner as to produce a residual oil -that is of very high grade and in the best possible condition for distillationinto lubrieating fractions. While it is believed that, in order to produce lubricating oils of the highest grade and of maximum yield, the residual oil produced by-the process hereinclaimed must be processed in accordance with the lubribating oil distillation process Vset forth in said application, it will be understood that the residual oils produced by the process herein claimed may be subjected to any known distillation process and will result in the production of higher grade oils than will be produced by such known process v applied to crude oils that have been topped by other processes than that herein described.

In order to facilitate a description of my improved process,.I have designed anapparatus especially adapted to the carryingout of the process, the drawings l(Fig. 1A andi .'Fig. 1B) comprising a diagrammatic view thereof. The practice of the process is not dependent, however, on the employment of any 'particular apparatus. It should also be understood that many of the hereinafterl de, scribed steps of the process are preferential merely. Y

Crude oil is pumped through pump 61 and line 62 through the tubes in reflux condenser 63. Here the crude'is raised in temperature about 20 F; by heat exchange with the vapors from tower 78. The rise in tem- 00 toV perature will vary with the grade of crude and the amount of vapors ycoming olf the towers. The heated crude, continuing its passage through line 62, goes to reiux condenser 64,A

where'it is heated to (say) 140 F. byheat exchange with the vapors. from tower 90. The crude then passes through heat,exchanger 65, where it is in heat exchange relationship with residual oil, as hereafter described. Leaving this heat exchanger at a temperature of (say) 310" F., the crude then passes to a bathed tank 67 held under a pressure of (say) 100'pounds gauge. This tank is of such a size that the oil flows through at a velocity preferably not exceeding about 25 ft. per hour. At this velocity, and at the last mentioned vtemperature and pressure, the salt water contained in the crude, which may amount to about 'two per cent. or over, settles to the bottom of the tank,'where it is drawn oi through draw-0E pipes 68. By removing the salt water, subsequent troubles due to salt deposit are eliminated, thus. greatlysimplifying the problem of continuously running the process with avoidance of frequent shutdowns for cleaning the tubes of the pipe stills. The removal of the salt also enablesa better grade of asphalt (if the crude has an asphalt base) Vto be obtained at a final stage of the lubricating -oil distillation process; such asphalt having lsuperior solubility tests, i. e., containing a relatively-small percentage of insoluble material. f

Thev oil .from tank 67 lHows through the tubes 70 and 71 of a pipe still and thence into.

a vaporizer 75 at a temperature of (say) approximately 450 F. This pipe still may be of conventional design, fuel oil being burned through burner 137 in space 72, the products of combustion passing upwards over tubes 70, down over tubes 71, into flue 73, and thence up stack 74. In order to keep the gas temperature low in this furnace, the exhaust gases from pipe still 84-85 pass into the tire box 72 and are mixed with the products of combustion from burner 137. This-results in great economy of operation, as it enables the hotter gases from pipe still 84---85V to give up their heat in pipe still 70-71. rlhe flue gasV temperatures in flue 73 a're not above about 400 F.

The pressure in vaporizer 75 being substantially atmospheric, 'vapors are freed from the incoming oil as ittravels down over theV inclined plates. These vapors pass upwards through manifold 76, distributor section 77 :lid packed section 78, and out vapor line 79 into reflux condenserv 63. 'In the latter, the

Yvapors are condensed, the condensate being returned through lin'e 80 to the tower,.or

g through line 81 to storage, in such proportions as the operation of the tower requires', an increased amount being returned through line SO'tvhen a lighter product through line 81 is desired and a decreased amount when a 103 or tank 104, in which tank it is mixed heavier product is desired. The reiux from section 78 is caught in section 77 and passes through line 91 to storage. The product through line 81 is light gasoline and the prodict through line 91 is an intermediate gasoine.

The residual or partially topped oil, which may be said to be a light mazout, leaving the bottom of vaporizer passes through pump 82 and the tubes 84 and 85, Where it is heated to approximately 590 F. At this temperature, it passes into vaporizing tower 88, which operates in a manner similar to vaporizer 75. The product from this vaporizer that Vleaves through line 93 is light gas oil, and that which `escapes through line 92 is heavy gas oil.

The residual oil leaving the bottom of tower 88, Whichmay be said to be an intermediate mazout, passes through pump 96 at a temperature of (say) 580 F. and through a heat exchanger 66, in which it is cooled to (say) 500 F. The mazout at this temperature then goes through heat exchanger 65, where it exchanges heat with crude oil as previously described. The mazout leaves this exchanger at Vabout 360 F. and then goes through exchanger 66, wherein it is heated to about 480 F.

By this arrangement of exchangers, the mazout at its highest temperature does not directly heat the crude oil, but directly heats a more advanced part of the stream of mazout and then, at a reduced temperature (say 500 F.), heats theV crude oil and becomes then, at a still further reduced temperature,

the said more advanced part of the stream of subjected to a temperature in excess of about 500 F., it so locally overheats the lm of oil adjacent the heated surface of the passage through which the crude Hows that a deposit of salt is formed in the exchanger on 'the crude oil side. By the indirect heat transfer described, this highly objectionable condition does not occur.

y Leaving exchanger 66, the intermediate mazout passes through line 99 and into tank with approximately one per cent. of 38 B. soda. The soda is pumped into the tanks 'through line 107 and is thereinthoroughly mixed with the oil by circulation' through pumps 108 and 109. The provision of two tanks arranged as shown-affords a convenient means of avoiding a break in the continuity of the process. The voil Vfrom line 99 run (say) into tank 103 until it is practically full, all the-air in this tank having been expelled by steam. The soda is then admitted through line 107. A. pressure of (say) 360 pounds gauge is immediately generated, due to the vapor pressure of the water in the soda at this temperature. Pump 108 is then started and the mixture of oil and soda circulated through line 105 back to the tank and through line 105 again. This operation should be continued for about ten minutes, or such other and usually longer time as may be required to give an intimate mixture of soda and oil and to enable the soda to neutralize any acidity that may be in the oil. As an excess amount of soda is preferentially used the mixture will be alkaline.

Having Y valve on line 105 is' shut and the mixture is pumped through line 110 to tower 111. The time of pumping out tank 103 is so arranged that the same time interval will enable a fresh charge to be treated in tank 104. There# by acontinuous feed may be obtained in line 110.

The' mixture of soda and oil under pressure goes through 4-line 110 to vaporizing tower 111, whichA is maintained' at ,a substantially reduced-preferably atmospheric-pressure. Due to this reduction in pressure, enough specific heat is converted into latent heat to permit allthe water which is in the soda that will boil at a temperature of 460 F. to be vaporized. It is desirable to remove this water to as great a degree as possible to enable a greater vacuum to be. obtained in the subsequent distillation of the lubricating fractions. Thisobject tower 111 successfully ,accomplishes.V

40 Itis diilicult to get an intimate mixture between the oil and the soda when only a small proportion of the latter is added. However, -in my process, I secure the advantage of a larger amount of liquid caustic soda, as it is mixed, in tanks 103 and 104, under such conditions of pressure and temperature that the water will not vaporize. Then, in tower 111, the water'which wquld be highly objectionable at a later stage bf the process isremoved. I

The-steam generated in tower 111 passes upwards through manifolds 112 into 60ndenser `113. The mazout and soda. mixture passes out through line 114and pump 115 through back-pressure valve 140 into tank 116, where the` oil is flowed over vaporizing pans. This tank is maintained undera substantial Vacuum, say of 28 inches.' Due to the-@reduction in pressure from atmospheric, or'about 15V pounds absolute, to about two pounds absolute, enoughspecific heat is converted into latent heat to enable all the gas oil left in the mazout from the topping process to be vaporized and pass out through line 118 into tower 119.-

thus obtained the mixture, the-` temperature v'when distillation occurs under Due to the great velocities at'which vapors form and leave the surface of theA oil in the va- ,A porizing pans of tank 116, some entrainment of heavier oil may occur. Tle reflux condenser 120 at the top of tower 119 permits, by temperature control, the lighter products to pass out through line 121. and throws the heav products back down into trap 124, from vaghic should the entrainment be particularly objectionable, the heavier products iow back to the vaporizer; or, should the entrainment not be objectionable, such heavier products flow into a cooler 123, where it mixes with vthe overhead distillate flowing through line 121, condenser122 and cooler 123 into re- 80 ceiving tank 125. A vacuum is maintained on this tank by means of vacuum equipment 127. The oil is pumped from tank 125 by means of pump 126.

The oil leaving tank 110 through line 117 vv85 is now in condition to be subjected to fractional distillation for the production of lubricating distillates and .high grade asphalt. The part of the complete rocess carried out in the lubricating oil distillation apparatus, which is shown diagrmmatically. and lettered neednot be herein described, since'it forms no part of the invention herein claimed "and may be replaced by any vsuitable distil-- lation plant. The plant w is fully described in the hereinbefore mentioned application as Vwell as in an earlier applicationA filed by me May 2 9, 1926, Serial No. 112,485 whichma tured into Patent No. 1,761,151, on June 3, 1930.

It will be noted that at no stage of the described process is'the oil raised to a substantial cracking temperature, and that air is excludedthroughout the entire process. There can thus be formed neither those decomposition products that are formed, by cracking, when oil is exposed to high temperatures for a substantial length of timenor those oxidation products that are formed at a lower n conditions that do not exclude the presence of air. The fractionations are efficient, temperature and pressure conditions are carefully and accurately controlled, and the process may be so conductedthat the lightest substantial fraction of oil-that is distilled inthe process followingthat herein claimed will have a viscosityof over 100 seconds Saybolt at 100 F.

. Having now fully described my invention, what I claim and desire -to protect by. Let- .ters Patent is:

cluding access of ox ygen, subjecting the rfa-'130 perature below that at which substantial cracking occurs, then, adding an alkali solution to the residual oil and then, Without substantial application of heat and at a temperature below that at which substantial cracking occurs, subjecting the oil to sufH- ciently 10W absolute pressure to evaporate off solvent introduced withV the alkali and distil olf higher boiling point constituents of the oil and leave a residual product containing the desired` lubricating fractions, and substantially excluding access of oxygen throughout the process.

3. In the process of preparing crude oil for distillation of lubricating fractions, `subjecting the .oil to a superatmospheric pressure and mixing an alkali solution With the oil, then substantially reducin the absolute pressure on the thus treated oil While evaporating off most of the solvent introduced With the alkali and then subjecting the residual oil to a substantial vacuum While effecting partial vaporization of hydrocarbons leaving a residual product containing the desired lubricating fractions.

4. In the process of preparingcrude oil i for distillation of lubricating fractions, distilling off low boiling constituents at a temperat-ure below that at which substantial cracking occurs, then mixing an alkali solution With the residual oil, then evaporating i off solvent introduced with the alkali and without substantial application of heat subjecting the oil to a suiiiciently low subatmospheric pressure to distil E higher boiling point constituents and leave a residual i product containing the desired lubricating fractions, and substantially excluding access of oxygen throughout the process.

5. In the process of preparing crude oil for distillation of its lubricating fractions, l separating lighter hydrocarbons in a substam Atially uncracked condition, then mixing an alkali solution with the residual oil, then evaporating off solvent introduced with the alkali Without substantial rapplication of heat and at a pressure substantially above that hereinafter specified, and then subjecting! the oil to such substantially reduced subatmospheric vpressure and to such .tem- D perature--as to effect the vaporization of hydrocarbons heavier. than those previously separated, leaving a residual product conf taining the desired lubricating fractions.

6. In the process of preparing crude oil for distillation of lubricating fractions, disdistillation of lubrica tilling oil' low boiling constituents at a temperature below lthat at Which substantial cracking occurs, mixing an alkali solution with the residual oil, evaporating oif solvent introduced with the oil while maintaining the oil under an absolute pressure substantially above that hereafter specified, and then, without substantial application of heat and while subjecting the oil to a substantial vacuum, ei'ecting vaporization of higher` boiling constituents of the oil, leaving a residual product containing the desired lutions, and substantially excluding access of oxygen to the oil during the specified series of operations. y

8, The process of preparing crude oil for distillation of lubricating fractions, which comprises subjecting the oil to a first Vaporizing operation4 by applying extraneous heat to effect vaporization of relatively light hydrocarbons, add-ing to the residual oil an alkali solution and subjecting th'e oil to. such superatmospheric pressure that the later vat porizing operations hereinafter specified may be effected Without substantial application of extraneous heat by successive drops in pressure, subjecting the oil to a second vaporizing operation under a substantially reduced absolute pressure and so distributinghe oil and so regulating said pressure drop :is to effect evaporation of the alkali solvent, and subjecting the residual oil from the second vaporization to a third vaporizing operation under still further reduced absoluter pressure and so regulating the pressure drop and the tempera-ture as to effect evaporation of rela# tively heavy hydrocarbon constituents and leave a residual product containing the desired lubricating fractions.V

9. The process of pieparing crude oil for Eting fractions, which comprises establishing a flowing stream of oil and in the course of its iiow removing salt water from the oil under superatmospheric pressure, applying heat to the so purified oil and distilling off lighter hydrocarbons, transferring heat from the residual oil to the oil flowing toward the locus of salt water re- ,moval, adding an alkali solution to the cooled residual oil, distributing the oil so treated over a surface of large area and under such absolute pressure as to allow evaporation of solvent introduced with the alkali, and then distributing the oil over a surface of large area while subjecting the oil to such reduced and sub-atmospheric pressure as to' effect evaporation of hydrocarbon constituents which are higher boiling than those initially distilled off and leave a residual product conf taining the desired lubricating fractions.

10.'. In the process of preparing crude oil for distillation of lubricating fractions, removing salt water, distilling off low boiling constituents by the application of heat below a temperature adapted to effect cracking, adding an alkali solution to the residual oil, removing the alkali solvent, and then subjecting the residual oil, without substantial application of heat and at a temperature not above that acquired in the first mentioneddistillation, to .a\ subatmospheric absolute pressure sufficiently low, at such temperature 'to distil off higher boiling constituents of the oil and leave a residual roduct containing the desired lubricating actions.`

11. In the rocess of preparing crude oil containing sa t water for `distillation of lubricating fractions, establishing a flowing stream of relatively cool oil containing salt water, heating the oil in said stream by heat exchange at one locus 'with the residual oil stream hereinafter specified, substantially removing the salt water, distilling olf lighter fractions under heat conditions producing a residuum at a temperature substantially in excess of 500 F., establishing a iowing stream of residual oil, cooling the oil in the residual stream at a second locus by heatV exchange with a more advanced part of the residual stream and thereby reducing its temperature to not substantially above 500 F., further cooling said cooled residual oil at the first locus by the hereinbeforefspeciied heat exchange with the oil in the rst stream, and reheating theI thus cooled residual oil at the second locus by the hereinbwefore specified heat exchange with a less advanced part of the residual oill stream; whereby the oil in the rst stream is heated suiiicientl to enable the salt water to be subsequently su stantially removed while it is not hea-ted suiiicientlyl to Voverheat any part of the oil toform a salt deposit in the exchanger.

12. Inl he process of preparing crude oil for distillation of lubricating fractions, distilling off low boiling constituents at a temperature below 'that t which substantial cracking occurs and t en, at a temperature not above that of said distillation of lower boiling fractions, but under a high vacuum, distributing the residual oil over a surface of large 'area and evaporating therefrom higher' boiling-constituents, leaving a residual oil product containing the desired lubricating fractions, and substantially excluding ac- 'cess of.oxygen throughout the process.

13. In the process of preparing crude oil for distillation oflubricating fractions, distilling off low boiling constituents at a temperature below that lat whichI substantial for distillation of lubricating fractions, distilling oif low boiling constituents at a temperature belowthat at which substantial cracking occurs and then, at a temperature substantially below that at which lower boiling fractions a're distilled of, distributing the residual oil over a surfaceof largearea and evaporating therefrom higher boiling constituents, leaving a residual product containing the desired lubricating fractions, the last mentioned distillation being conducted under a vacuum suiiciently high t0 more than compensate for the reduction in temperature and substantially excluding access of oxygen throughout the process.

15.v In the process of preparing crudeoil for distillation of lubricating fractlons, distilling off low boiling hydrocarbons at a temperature v belen7 that at which substantial cracking permits, transferring heat from the constituents which are higher b/QilingI than those initially distilled off, leaving a residual product containing the desired lubricating fractions;

16. In the process of preparing crude oil i for distillation of lubricating fractions, distilling oif low boiling hydrocarbons at a temperature below that at which substantial cracking occurs, then'adding an alkali solu-` tion to the residual oil, and then, while the residual oil is at a temperature not above that of said distillation,distributing the residual oil so treated over a large area and under such absolute pressure as will effect evaporation of solvent introduced with the alkali and leave a residual product containing the desired lubricating fractions.`

17. In the process of preparing crude oilfor distillation of lubricating fractions, distillingof low' boiling hydrocarbons at a temperature below that at which substantial cracking occurs, then adding angalkali solution to the residual oil, then evaporating solvent introduced with the alkali, and then, ata temperature substantially below that of the distillation of said low boiling hydrocarbons, distributing the oil so treated over a surface of large area and under such high vacuum as to cause. evaporation of hydrocarbon constituents which are higher boiling than those initially distilled o and leave a residual product containing the desired lubricating fractions v 18. yIn the process of preparing crude oil for distillation of lubricating fractions, distilling off low boiling hydrocarbons ata temperature below that at which substantial cracking occurs and separating said low boiling hydrocarbons from higher boiling hydrocarbons containing the desired lubricating fractions, then adding an Aalkali solution to th higher boiling hydrocarbons while in liqui phase and at a temperature not above that of said distillation and distributing said higher boiling hydrocarbons so treated over a large ,area under such absolute pressure aswill ef` fect evaporation of solvent introduced with the alkali and leave a residual oil containing the desiredlubricating fractions.

19. In the process of preparing crude'oil for distillation of lubricating fractions, dis# tilling off low boiling hydrocarbons at a temperature below that at' which substantial cracking occurs and separating said low boiling hydrocarbons from higher boiling hydrocarbons containing the desired lubricating fractions, then adding an alkali solution to the higher` boiling hydrocarbons lwhile in liquid phase and at a temperature not above that of said distillation-and distri utin said higher boiling hydrocarbons so t ate over a large area under such labsolute ressure asv will effect evaporation of solvent introduced with the alkali and then distributing the re sidual oil overa surface of lar e area under such reduced and subatmospherlc pressure as will 'effect evaporation of lower boiling constituents of the residual oil and leave a residual product constituting eating Qil stock. Y

20. The method of distillingV petroleum which comprises' subjecting it to distillation continuously by passing it through a pipe ycoil and heating it therein to a temperature sufficient to vaporize considerable proportions `of the oil contained in the petroleum, discharging the resultingproduet into a vapor separating chamber at approximately at-x mospheric pressure with resulting production of distillate oils `and-a residual oil, withdrawing the residual oil and reducing the pressure onthe residual oilbysubj ecting it to a high vacuum while it is still at a suiiclently high temperature to eliectdistillation of additional oils therefrom. i 1

'21. The method of distilling petroleum which comprises forcing the petroleum con.

'ing the resulting product into a vapor sepa- Y therefrom, withdrawing the residual oil from the desired 1ub1i-`collect1ng.and condensin .ing hy tinuously under pressure through a pipe coil and heating it therein to a temperature suiiicient to vaporize considerable proportions of the oil contained in the petroleum, dischargrating chamber .at approximately atmospheric pressure and thereby effecting separation of oil vapors from residual oil, drawing off the oil vapors and subjecting them to condensation to recover distillate oils therefrom, drawing oif the hot residual oil and subjecting it to a high vacuum while'it is j still at a high temperature and thereby effecting further distillation of oils therefrom with reduction of temperature, condensing the distillates produced by such vacuum distillation, and separately drawing off the residual oil from such vacuum distillation.

22. The method of distilling petroleum which comprises subjecting petroleum to distillation continuously by passing the petroleum through a pipe coil and heating it therein to approximately the maximum temperature towhich it can be heated without objectionable decomposition and discharging the heated product into a vapor separating chamber at approximately atmospheric pressure, withdrawing the vapors produced by such distillation and condenslng the oils such ldistillation and subjecting it to. a high vacuum while it is still at a high temperature and thereby eecting further distillation of oils therefrom without objectionable decomposition of the residual oil, and separately condensing the distillates so produced.

23. The method of distilling! petroleum which comprises first subjecting petroleum to distillation at substantially atmospheric' pressure to produce distillate oils and a residual oil by heating it in a pipe coil to a temperature sufficient to vaporize considerable proportions of the oil L)contained in the petroleum, discharging the resulting product into a vapor separating chamber at approximately atmospheric pressure, separately the oil vapors thus produced and withdrawlng the residual 011 continuously while it is still at approximately the temperature of the first distillation and subsequently subjectin I it -to a high vacuum to effect further-distil ation of high boiling Vpoint oils therefrom by the'self-contained Yheat of the hot residual oil. 24. In thevv process of preparing crude oil for distillation of lubricating fractions, distilling o# low boiling hydrocarbons at a temperature Abelow that at which substantial crackin occurs and separating said' low boilrocarbons from higher boiling hydrocarbons containing-the desired lubricating fractions, then `adding an alkali solution to the higher boiling hydrocarbons while in liquid hase and at a temperature not above that o aiddistiuauon and distributing Said 1'30' higher boiling hydrocarbons so treated over a arge area under such absolute pressure as will ei'eot evaporation of solvent lntroduced with the alkali and of such oil fractions as evaporate at such pressure and temperature and leave a residual oil containing the desired. v lubricating fractions. In testimony of Which invention, I have hereunto set my hand, at Philadelphia, Penna., on this 15th day of December, 1926. ARTHUR E. PEW,JR.

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