US1998765A - Process for neutralizing organic acidity in petroleum lubricating oils - Google Patents

Description

April 23, 1935. w. B, LOGAN 1,998,765

PROCESS FOR NEUTRALIZING ORGANIC ACIDITY IN PETROLEUM LUBRICATING OILS Filed Oct. 8, 1931 fifl/POMETP/C CONDENSER H519 TEE F/POM ST/LL W/LL/fiM B L 066W INVENTOR H/5 ATTO R N EY Patented Apr. 23, 1935 r 1,998,765

UNITED STATES PATENT'OFFICE PROCESS FOR NEUTRALIZING ORGANIC AOIDITY IN PETROLEUM LUBRICATING OILS a William B. Logan, White Plains, N. Y., assignor to The Texas Company, New York, N. Y., a corporation of Delaware Applicationoctober 8, 1931, Serial No. 567,535

'3 Claims. (01. 196 -35) This invention relates to the manufacture of jected to distillation under subatmospheric preslubricating oils and more particularly to aprocess sure conditions, and while still in the presence of obtaining lubricating oils in improved form of the alkali material to produce the desired lufrom' crude petroleum. bricating 'oil fractions free from organic acids.

5 The invention contemplates improvements in The vacuum distillation may be carried out either 5 the manufacture of hydrocarbon lubricating oil in a plurality of shell stills from each of which a from crude petroleum'especially from crudes of desired vapor fraction is removed, or in a dethe naphthene and mixed base types. The inphlegmating or fiash'column from which a pluvention comprises preparing a lubricating oil conrality of liquid streams, each-of desired viscosity taining fraction from the crude, and treating the characteristic, may be withdrawn at successive 10 fraction with an alkaline material during heatpointsin the column. The vacuum distilling sysing in the liquid phase to eifect chemical reactem is maintained under a low absolute pressure, tion between the alkaline material and the acidic preferably not in excess of about four or five constituents of the oil, following which the oil is inches of mercury, while the temperature of the 16- subjected to distillation, p a y nd sub oil may range from around 400 to not greatly atmospheric pressure, for the production of dein excess of about 700 F. or 750 F. sired lubricating oil fractions free from natural- In the prior art where oil has been dist d ly-eeelllring d her aeld e Co ti uents. in the presence of caustic 'or other alkaline ma- Aeeelding to my invention, crude Oil is Cha ed terial s, it has been the practice to introduce the 20 to a p pe s ill or other sui ble distilling m an alkali directly into the still in which'distillation 20 Which may be adapted to op at a p i occurs. When alkali in the form of an aqueous pressures and wh h gasoline, kerosene d solution is introduced into the hot still in-this the larger portion of the s Oil Constituents of way, the aqueous portion thereof is immediately the crude are removed; T remaining or and instantaneously flashed into vapor, where- 25. dua 'p rt n 'f th ud nta n the u iupon the alkali salttends to settle out of the oil at fractions y constitute the fraction on to the. still bottoms. Thus a relatively large d in tr atm nt a di to v v ti proportion of the oil is vaporized within the still On the other hand,adistillate lubricating oil'fracith t akin any appreciable contact with t n i rm d at tw the gas oil a d t the alkali, while the unvaporized portion of the 30. idual r fu l il p t n of t rud ma b oil makes scarcely any more contact with the p pa a va s by subje t g the salt due to the rapidity with which the solid ma- Dp Crude 0 distillation under subatmosphelie terial settles out. The result is that there is pressure scarcely any opportunity afforded for the alkali The resulting lubricating Oil distillate pp to react with the acidic constituents of the oil.

- u a the Case may is mixed With strong These acidic constituents, particularly the natu- 35 k i s u o in suitable miXiilg Contacting rally-occurring constituents, such as naphthenic means p to n ly disperse the so u acids and the like, require prolonged and intimate throughout the y of O and-the mixture then contact'with the alkali at elevated temperatures p s through heating Cells wherein it is in order to completely react therewith. The

40, gested while maintained in substantially the necessary t t t e alkali and 11 is 40 qu phase du n at up to t peratur s alized only when it is maintained in contact with corresponding substantially t the d s n t mthe oil in the form of an aqueous solution; other- D a 0f the Oil at Pressures less than wise, as has been the case hitherto, the reaction m sp a. The p a u s prevailing duri is far from complete and the resulting vaporized pass f h ixtu th u h t h at il oil has contained large amounts of undesired 45 may range from 100 F. to around 700 F. or even a idi material.

higher, depending upon the nature of the oil un- In certain instances, the treatment of hydrodergoing treatment, While pressures of around 100 carbon oils with caustic or alkali has, in'the past, pounds 1 at least sufficient to prevent t nbeen restricted to a rather secondary or final op- 50, tial vaporization of the oil as well as of the alkali eration, usually following acid treatment of the s u y be p ed upon the mixture while oil. The alkali material has been immediately P s through a able portion of the separated from the oil and the oil then usually coil so as to maintain suitable and effective condiwashed with Water to remove last traces of the tions of digest during a sufficient period of time. caustic before undergoing any further treatment.

o5. The digested and heated mixture is then sub- I have discovered that by digesting lubricating oil distillate with caustic soda or other suitable alkali material in aqueous solution at substantially the distilling temperature of the oil but while maintaining the oil in liquid phase and then without removing the caustic or caustic reaction products, immediately subjecting the oil to distillation into desired fractions or cuts, and while still in the presence of the caustic an improved product results. The resulting product is of such quality that acid treatment may be entirely omitted if desired.

The operation of the invention will now'be described in connection with the accompanying flow diagram showing one form of apparatus suitable for carrying out the invention.

Lubricating distillate or topped crude, as the case may be, is drawn either from a storage tank I or directly from distilling means and delivered through a pipe 2 to a mixer 3 wherein the oil is brought into intimate contact with alkali solution. The alkali solution, which may comprise caustic soda of from 30 to 40 B. gravity, is introduced to the mixer from a storage tank 4 by a suitable proportioningpump 5. The mixer may consist of a. closed drum containing packing material jet or baffles, or may comprise any other suitable type of mixing means adapted touniformly and finely disperse the alkali solution throughout the body of the oil.

The mixture of oil and alkali solution is passed from the mixer through a pipe 6 to a pipe coil heater 1 advantageously of the single continuous tubular type wherein the oilis maintained in turbulent flow during passage therethrough so as to maintain the alkali solution and oil in an intimate state of admixture and thus avoid the separation of the alkali from the oil. The coil is preferably of such type that the mixture may traverse a distance of several thousand feet under highly turbulent conditions of flow and under conditions of pressure and temperature such that the alkali solution is advantageously maintained in substantially a liquid phase so as to facilitate more effective contact with the oil. During flow through the remaining portion of the coil, the mixture is subjected to still higher temperatures and passes through a zone wherein it may be largely vaporized.

In the case of a lubricating distillate fraction, the oil and alkali mixture may be heated to temperatures up to from 500 to about 700 F. while in the case of a heavier residual fraction, the temperatures may be around 750 F. or even higher. Thus, the mixture of oil and alkali is subjected to heating at elevated temperatures to effect reaction between the alkali and the acidic constituents of the oil, preferably while maintaining the oil in a substantially liquid phase condition. By maintaining rapid and turbulent flow of the liquid through the heating coil, subjection of the oil to cracking conditions for appreciable periods of time is avoided.

The pressure at the outlet of the coil maybe maintained at atmospheric pressure or thereabouts but may be less than atmospheric at this point as already set forth, the extent of such pressure being controlled by means of a control valve 8 located in the discharge pipe 9 from the heater 7. The heated mixture of oil and alkali, after passage through the valve 5, is introduced to a dephlegmating column I!) maintained under a low absolute pressure, preferably not in excess of about two or three inches of mercury.

The oil is flashed into vapor in the lower portion of the column and the vapors as they rise towards the top of the column are subjected to fractionation and partial condensation into desired fractions which are withdrawn as side streams from the column.

Steam may be introduced to the bottom of the column l through a spray H for the purpose of facilitating the vaporization of the oil. Reflux or cooling liquid may be introduced to the top of the fractionator through a spray I2 to supply the necessary cooling thereto so as to control the degree of condensation. The desired lubricating oil fractions are removed as side streams from the fractionator through pipes I3, 14, etc.

The remaining uncondensed and gaseous material, including water vapor, is removed from the top of the fractionator through pipe 55 to a barometric condenser l6 wherein it is contacted with cooling water admitted to the barometric condenser through a pipe H. The fixed gases and other incondensable material accumulating in the barometric condenser are removed therefrom through a pipe 18 to a vacuum pump $9 from which they may be exhausted to the atmosphere and by which means the desired (16-- greeof vacuum is maintained on the column 2|.

The residual matter collecting in the bottom of the column l0, composed of tarry constituents together with the caustic reaction products, is withdrawn therefrom through a cooling worm 20 from which it may be conducted .to tankage.

It is contemplated that the temperatures and pressures described in connection with the foregoing example may be varied as desired, depending on the nature of the oil undergoing treatment. The invention maybe readily adapted to the treatment of various distillates or residual fractions derived from different crude sources, such-as naphthene or mixed base crudes, as may be obtained from Gulf Coastal and 'Midcontinent fields. i

Obviously many modifications and variations of the invention, as hereinbefore set forth, may be made without departing from the spirit and scope thereof, and therefore .only such limitations should be imposed as are indicated in the appended claims.

Iclaim:

1. The method of simultaneously separating heavy residual petroleum lubricating oil stock into lubricant distillate fractions while removing the naturally occurring acids therefrom, which comprises admixing the oil stock with a concentrated aqueous caustic soda solution, flowing the mixture in a confined turbulent stream through a heating coil and rapidly heating it to a temperature of'around 750 F. or higher while under sufficient pressure to maintain in substantially the liquid phase, flashing the heated mixture withoutprevious removal of water vapor directly into an intermediate portion of a fractionating zone maintained under high vacuum, passing unvaporized oil downwardly through a lower portion of the fractionating zone and subjecting it therein to further distillation, fractionating the vapors to condense a lubricant fraction in the fractionating zone, removing such lubricant fraction as a side stream from the fractionating zone, and removing water vapor and remaining vaporized constituents overhead from the fractionating zone.

2. The method of simultaneously separating heavy residual petroleum lubricating oil stock into lubricant distillate fractions while removing the naturally occurring acids therefrom, which comprises admixing the hydrocarbon oil with an excess of a concentrated aqueous caustic soda solution, fiowing the mixture rapidly in a confined turbulent stream through a heating coil and rapidly heating it to a temperature of around 750 F. or higher while under sufiicient pressure to maintain in substantially the liquid phase, flashing the heated mixture without previous removal of water vapor directly into an intermediate portion of a fractionating zone maintained under high vacuum, passing unvaporized oil downwardly through a lower portion of the fractionating zone countercurrent to steam to effect further distillation thereof, fractionating the vapors to condense lubricant fractions in the fractionating zone, removing such lubricant fractions as side stream from the fractionating zone, removing water vapor and unvaporized constituents overhead from the fractionating zone, and removing residuum from the lower portion of the fractionating zone.

3. The method of simultaneously separating heavy residual petroleum lubricating oil stock into lubricant distillate fractions while removing the naturally occurring acids therefrom, which comprises admixing the oil stock with a concentrated aqueous caustic soda solution, flowing the mixture in a confined turbulent stream through a heating coil and rapidly heating it to a temperature of around 750 F. or higher while under suflicient pressure to maintain in substantially the liquid phase, flashing the heated mixture without previous removal of water vapor immediately into a fractionating zone maintained under high vacuum, passing unvaporized oil downwardly through a lower portion of the fractionating zone and subjecting'it therein to further distillation, and fractionating the vapors to condense a lubricant distillate fraction substantially free from organic acidity.

WILLIAM'B. LOGAN.

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