US1746916A - Manufacture of lubricating oil - Google Patents

Description

Feb. l1, 1930. G. H. TABER, JR 1,746,916

MANUFACTURE OF LUBRICATING OIL Original Filed Jan. 14. 1925 ,(QW'WMM, r ATTORNEY Patented Feb. 1l, 1930 T FIC GEORGE E. TABER, JR., F RYE, NEW YORK, ASSIGNOR TO SINCLAIR BEFINING COMPANY, OF NEW YORK, N. Y., A CORPORATION OF MAINE MANUFACTURE 0F LUBRICATING OIL Original application le January 14, 1925, SeriaLNo. 2.262. Divided and this application led December i5, 192s. vaerial No. 326,219.

This invention relates to improvements in the distillation and refining of lubricating oils. The invention provides an improved method of producinglubricating oils from 5 oils and' distillates containing lubricating oil fractions, such as crude petroleum oil, topped crude oil, and crude lubricating .oil distillates. The invention includes an improved combined distilling and refinl0 ing o ration, improvements in the fractionation of oils and distillates containing lubricating dil for the separation of the desired lubricating oil fraction free from heavier and li hter components, an improved l5 method of re ing lubricating oils, and improvements in continuous distillation processes for the roduction of lubricating oils. This application is a division of an application filed January 14, 1925, Serial No. 2,262.

l0 Hitherto in the methods generally ernployed for the production of lubricating oils from crude oil, the crude oil has been initially subjected to a fractional distillation, either by batch operations or in a series of continuous stills, and a broad lubricating oil distillate `fraction thereby separated from the crude oil; and this lubricating oil fraction has then been subjected to redistillation in the presence of caustic alkali introduced directly into the Y 0 body of oil undergoing distillation for the production of refined lubricating oil distillates, the caustic alkali solution being employed to remove undesirable constituents such as naphthenic acids and asphaltic compounds v'vhich if allowed to distill over with the finished lubricating oil distillates would render them' bad colored and difficult to handle in further treatment. It has been proposed to apply the caustic alkali treatment 0 directly 4to the crude oil undergoing distillation during the time in which the broad lubricating oil fraction was being produced, but such proposals have not been successful principally because of excessive depositionl comprises vaporization of the lubricating oil fractions from the crude lubricating oil-containing oil or distillate, treatment of the vaporized lubricating oil constituents with a treating agent, more particularly caustic al kali, and recovery of the treated lubricating oil constituents.

According to the present invention, the vaporized lubricating oil constituents are subjected to treatment with caustic alkali While primarily in the vapor phase, and any condensate formed in the treating operation is also subjected to treatment in the liquid hase. The alkali treatment of the lubricating oil fraction or fractions is thus effected before or as the lubricating oil constituents are condensed and in this Way redistillation for treatment of the lubricating oils with caustic alkali is eliminated. Moreover, the refining operation, when carried out in this way, has several other important advantages. Thorough and intimate contact between the caustic alkali and the lubricating oil is effected and the refining action advantageously promoted. Likewise, the entire lubricating oil distillate fraction is positively subjected to thorough treatment with the caustic alkali; in the ordinary distillation with alkali the initially distilled components may escape without thorough contact with the alkali. The caustic alkali treatment ofl the present invention also may be combined advan tageously with a fractionating operation for separation of the desired lubricating oil fractions. The elimination of a distilling opera tion, particularly the crude'distillation as i ordinarily carried out, also assists in eliminating cracked products from the finished lubricating oil products. Cracked constituents are usually characterized by low viscosity as compared to their boiling point and are accordingly usually objectionable in lubricating oils of corresponding boiling range. Other advantages of the invention will be apparent from the fol-lowing description.

In carrying out the present invention, the lubricating oil fraction may be vaporized from the crude oil or crude lubricating oil' distillate in a vaporizing still and this vaporization may be eected under atmospheric still may be controlled so that only the desired vapors of the desired lubricating oil fraction are produced. Where a fractionating tower is employed, it may be externally cooled. or it may be cooled by introduction of a refluxing agent s uch as a portion of the distillate produced in the operation; and the fractionating tower may be arranged to discharge reflux backinto the still or the heavier constitutents separated in the tower may be removed from the tower without being returned to the still. Vhere a fractionating tower is employed in connection with the vaporizing still, the crude oil or crude lubricating oil distillate may be introduced into the tower and employed as a refl'uxing agent therein; and the operation of the tower and vaporizing still may be controlled so that vaporization of the desired lubricating oil fraction from the crude-material introduced into the tower is substantially completed in the tower. A

' From the vaporizing still, or from the fractionating tower connected with the vaporizing still, the vaporized lubricating oil constitutents are conducted to a treating tower in which they are subjected to treatment with caustic alkali in accordance with the present invention. In the treating tower, the lubricating oil vapors are thoroughly and intimately contacted with a caustic alkali solution. The treating tower may be of conventional baille tower construction arranged for introduction of the vapors into the lower part of the tower and of the treating solu tion into the upper part of the tower so that the lubricating oil vapors are contacted in counter current flow with the caustic alkali solution. In the treating tower, apart of the oil vapors are condensed and the condensate mingles with the used treating solution. The caustic alkali content of the condensate mixture may be em loyed for recirculation through the tower ihr further treatment of the lubricating oil vapors passing therethrough. v

y The caustic alkali solution employed may, for example, be an aqueous solution of sodium hydroxide of a density of between about 10 and 20 B. The minimum amount of caustic alkali solution employed should be at least suflicient to remove the undesirable constitutents from the lubricating oil tower with the condensation of an increased proportion'of the vapors therein. Condensation within the treating tower may be regulated by controllingthe amount of treating solution introduced therein. lVhere an aqueous solution of caustic alkali is employed in the treating tower, part of the water may be evaporated from the solution in the tower Y with resulting increase in concentration of caustic alkali in the solution, and the condensate mixture, including the used caustic alkali solution and any condensate produced in the treating tower, which accumulates may comprise a suspension of Vcaustic alkali in oil in admixture with a more or less. concentrated solution of caustic alkali. This mixture, with such -additions of fresh caustic alkali solution as are necessary to replace alkali consumed in the treating tower, may

be recycled through the tower for further treatment of the lubricating oil vapors passing therethrough. Before being recycled through the tower, a separation` may be effected between the oil component of the mixture and the caustic alkali-containing component, and the separated caustic alkali .containing component of the mixture returned to the-treating tower.

By appropriately regulating the cooling eifected in the treating tower, for example by controlling the amount olf-,treating solution,

circulated through the tower, a lubricating oil distillate fraction may be separated from the vapors in the treating tower. A lubricating oil fraction may similarly be separated in the treating tower by externally cooling the tower. After discharge from the treating tower, the condensate mixture may be cooled and the lubricating oil fraction separated from the used caustic alkali solution, for example by decantation after allowing the caustic alkali solution to settle. In this Way, a refined lubricating oil fraction, free from the lighter vapors which escape through the treating tower uncondensed, can be produced in the treating tower. In such an operation, additional caustic alkali is employed with advantage for promoting the condensation in the treating tower since the excess of caustic alkali solution facilitates the separation of the used causticalkali solution from the condensed lubricating oil fraction. By

7 Where the vaporize carrying out the operation in this manner, in conjunction vwith a vaporizing still having a fractionating tower thereon, a closely controlled fraction can be separated in the treating tower, heavier constituents being removed from the vapors in the fractionating tower and lighter constituents escaping through the treating tower uncondensed.

The operation of the treating tower may also be regulated so that the main portion of the vaporized lubricating oil constituents pass therethrough without being condensed therein. For carrying out the operation in this way, the treatinor tower may be thoroughlylagged to preventtheat lossand the treating solution may be preheated before introduction into the treating tower. For example, the condensate mixture from the treating tower, or the alkali containing component of the condensate mixture, may be admixed with fresh alkali solution without intermediate cooling and the mixture directly reintroduced into the tower. In thismanner, the treating tower operation can be controlled so that only heavier constituents are condensed therein and so that only a minimum propor-v tion of such heavier constituents are condensed. Any lubricating oil constituents condensed in the treating tower may be separated from thetower condensate mixture and recovered.

The uncondensed vapors escaping from the treating tower are condensed7 for example in an ordinary water cooled condenser. Where the main portion of the lubricating oil fraction is separated in the treating tower, the condensate from the vapors escaping from the treating tower comprises the lighter constituents uncondensed in the treating tower. Where the treating tower is operated to condense a minimum proportion of the lubricating oil fraction, the condensate from the vapors escaping from the treating tower comprises the lubricatin `oil distillate fraction. constituents escaping from the still, or from the fractionating tower on the still, include constituents lighter than those desired in the lubricating oil fraction, this final condensate also includes such lighter constituents and may be subjected to further 'treatment for the separation of these lighter constituents therefrom. The vaporizing operation and the initial fractionating operation, however, may be controlled so that the final condensate produced from the 'vapors escaping from the 'treating tower is the desired`lubricating oildistillate fraction.

Before the vapors escaping from the treating tower are condensed,'.they may be subjected to a further lfractionating o eration. They may, forexaniple, he passed t rough a second fractionating tower in which the desired lubrieatin oil fractions are condensed and through which the constituents lighter than those desired in the'lubricating oil fra/etions are allowed to pass uncondensed. Such a second fractionating tower may be employed in conjunction with the treating tower for the production of a closely controlled lubricating oil distillate fraction by regulating the operation of the treating tower to condense heavier constituents and by regu. lating the operation of the second fractionating tower topermit lighter constituents to escape uncondensed therethrough. Where such a second fractionating tower is employed, a heavier lubricating loil fraction may be separated in the treating tower and a lighter lubricating oil fraction, whichhowever is free from the lightest undesirable constituents, can be separated in the fractionating tower. l

The process of the present invention may be carried out in conjunction with awseries of continuously operated vaporizing stills in which a series of progressively heavier fractions are treated Afor the separation of progressivcly heavier distillates, or through which the crude oil or Icrude lubricating oil distillate is successively passed with the vapor-ization therefrom of progressively heavier fractions in successive stills ofthe series. lVhere the vapors from several such stills are passed throughtreating towers in which they are subjected to treatment withl caustic alkali in accordance with the present invention', the oil component of the condeni "sate mixture separated in towers operating on lighter vapors may benintroduced into` treating towers operating on heavier vapors with improvement of the fractionation effected in the several distillation stages. The separated' caustic alkali mixture is .reused in the treat- `ing. tower from which 1t 1s dlscharged.

The invention will be further described in connection with the accompanying drawing which illustrates, in a diagrammatic and conventional way, one formfof apparatus adapted for the practice of the process of the 1n vention; but it will be' understood that this further description and illustration are intended for the purpose of exemplitication and that the invention is'notlimited thereto.

The apparatus illustrated comprises a raporizing still5, a fraetionating tower 6, a treating tower 7, and a cooler and condenser 8. The still illustrated is of the direct fire heated type and is provided with perforated pipes 9 for. the direct introduction of stca'm into the body of oil in the still. The perforated pipes 9 are connected toa lcommon header 10 which is in turn connected to a steam boiler. T he still is also provided with a'char ing line V1l and a residue draw-of`12. The ractionating tower 6 is arranged abovethestill. `This tower is` provided with a helicalfbaiile 13 and the vapors from the still pass upwardly through the helical passage. in the tower escaping from tho upper end of the tower through the vapor line 14. Connections 1.5

f the upper end of the tower.

and 16 are arranged near the up er end of the tower for theintroduction oi) charging stock into the still through the tower or for the introduction of a reluxing medium into the tower.

From the vapor line 14 the vapors enter the treating tower 7, the tower shown being of convent-ional baille construction, and pass up wardly therethrough about the batlles 17 arranged in the tower. A pump 18 is arranged to force caustic alkali solution into the upper end of the treating tower through connection 19 and the spray head -20 arranged in The vapors rising through' the treating tower escape through the vapor line 21 to the condensing coil 22 from which condensate is discharged through the look box as into the receiver 24. The look box is provided with a gas vent 25, and, in operating at approximately atmospheric pressure, the valve 26 is closed and the valve 27 opened, any gases escaping through connection 28. The condensate may be withdrawn from the receiver by means of pump 29 or may be discharged through connection 30. The treating solution 1s supplied to the pump 18 through connection 31, which communicates with tank 32 through connection 33 having valve 34 therein and with tank 35 through connection 36 having valve 37 therein. The condensate mixture collecting in the lower part of the treating tower 7 is dischar ed through connection 38 to the tank 32. onnections are a'rran ed and valves 39 and 40 are provided for is-A char ing the condensate mixture from the treatin tower to the tank 32 either through the coo 'ng coil 41 and the connection 42 or through the bypass connection 43 and the connection 42. The connection 42 may include a pump 44 for returning the condensate mixture to the tank 32. The tank 35 is provided for storing fresh caustic alkali solution and is provided with a charging connection 45.

The condensate mixture returned to the tank 32 from the treating tower may be recirculated through the treating tower by means of pump'18, or a separation of condensate and treating solution may be eiected in the tank 32. The oil condensate is lighter than the adm ixed caustic alkali solution and tends to iloat thereon; and connection 46 is provided forwithdrawing separated 011 from the upper layer collecting in the tank and connection 47 for withdrawing used .caustic solution from thelowervlayer. A separation may thus Ybe effected in the tank 32 between the oil and the used caustic solution of the condensate mixture,land as much of the used caustic solution as may be desired may be re-em loyedin the treating tower together with resh caustic solution from the tank 35.

The exposed parts of the still 5 and the fractionatingjtower 6 and the vapor line 14v the fractionating` tower 6 and the treating tower 7 are vsuitably constructed .and reinforced to prevent collapse under the excess of atmospheric pressure prevailing on the outside over the reduced pressure within the distilling apparatus, and suitable precautions are taken to prevent inleakage'of air. The several vapor connections and' the passages through the fractionating tower and treating tower are also made of sutlcient crosssectional area so that thedesired degree ofl vacuum can be maintained without excessive consumption of power. For maintenance of subatmospheric pressures within the distil- \l1ng system, the vacuum pump 48 is arranged for exhausting uncondensed vapors and gases and the pump 29 isemployed for removing condensate from the system. "For operation under reduced pressures the valve 49 in the connection 30 and the valve 27 in the connection 28 are closed. The gasesand uncondensed vapors separated in thel look box 23 are withdrawn through vconnection 50 and any gases and uncondensed vapors collecting in the upper part of the receiver l24 are with' drawn through the connection 51 by means of the vacuum'pump.v Where thea paratus is operated under a vacuum, the v ve 52 in connection 42 is closed and thepump 44 is employed for returning the condensate mixture from the treating tower7 to the tank 32.l

In carrying out the processy of the inventionin the apparatus illustrated the still 5 is charged through the charging line 11 with oil or distillate containing the lubricating oil fractions. The still is heated and as vapors from the still rise through the fractionating tower 6 the feed'of additional lubricat-` ing oil-containing .charging stock is begun through connection 15. .The distillation may be promoted, by the introduction of live steam directly'into the body of oil in the still through connection 10. The supply of additional charging stock through connection 15 may be regulated to control the relluxing op eration in the fractionating tower, and this control may be supplemented b the introduction ofa regulated amount o a retluxing agent through connection 16. The reuxin'g agent employed may, for example, be oilV separated from the condensate mixture lco1- lecting in tank 32, or part of the distillate collecting in the receiver 24, or fractions of corresponding character. The fractionating operation is regulated so that the desired. lu-

bricating oiI constituents escape from the upper end of the fractionating tower 6 through the vapor line 14 and these lubricating oil vapors enter the treating tower 7. In the treating tower 7 the lubricating oil vapors are contacted in counter-current flow with a caustic alkali solution supplied to the upper end of the tower through spray head 20 by means of the pump 18. This caustic alkali solution may be fresh solution from the tank 35, or a solution or `a suspension of caustic alkali withdrawn from the tank 32, or a mixture of the two.

For the separation of a lubricating oil fraction in the treating tower, the circulation of treating solution through the tower is regulatedto effect condensation therein of the desired lubricating oil constituents. The condensation effected b the treating solution, and'by evaporation o water from the solution where an aqueous solution is employed, may be supplemented by external cooling of the treating tower. Where the condensate mixture or part of the condensate mixture is recirculated through the treating tower the condensate mixture may be cooled by circulation through the cooling coil 41 on its way to the tank 32. After separation from the used caustic solution in the tank 32, the lubricating oil fraction condensed in the treating tower 7 is withdrawn through connection 46, and may be subjected to further settling or washing treatment or other suitable treatment for the separation of any remaining admixed caustic alkali.

F or circulating the main portion of the lubricating oil vapors through the tower withy a minimum of condensation therein, the treating tower is lagged and the circulation of treating solution through the tower is maintained at the minimum necessary to effect the desired refining operation. The condensate mixture from the treating tower 7 may also be run to the tank 32 through the by-pass connection 43 without intermediate cooling, and caustic alkali solution for circulation through the treating tower made up of caustic alkali withdrawn from the heated contents of the tank 32, alone or in admixture with fresh solution from the tank 35, so that the treating solution entering the treating tower 7 throu h the spray-head 2() is in effect preheate The lubricating oil vapors escape from the treating tower through the vapor line 21 and are condensed and collected in the receiver 24. Where the operation is carried out continuously in. this manner, the' condensate collecting in the receiver 24 may include, in addition to the lubricating oil constituents, some lighter constituents which may be removed by further treatment. Any lubricating oil constituents condensed in the treating tower collect in the tank 32 and may be withdrawn therefrom after separation rom the caustic alkali solution therein.

The invention relates more particularly to operations in which fresh oil is supplied to the vaporizing still and residual oil withdrawn therefrom and in which a fraction of substantially uniform character is separated. The process of the present invention is also applicable where the distillation is carried out upon successive charges of oil with the successive separation of progressively heavier cuts either in the treating tower or in the condenser or in both. The operation, for example, may be carried out by charging the still with oil and progressively distilling oil therefrom, permitting lighter constituents undesirable as lubricating oil constituents to escape through the treating tower, beginning the introduction of caustic alkali solution into the treating tower as lubricating oil constituents begin to come over, and separating the distillate into the desired cuts.

The operation may be carried out under substantially atmospheric pressure. It will be understood, however, that if the pressure in the receiver 24, for example, is approximately equal to atmospheric pressure the pressure in the still will be somewhat greater due to the resistance of flow of the vapors through the apparatus, but by suitably proportioning the cross sectional area of vapor passages through the apparatus to rovide for free vapor flow this resistance an the consequent increase in pressure may be made substantially negligible. The still ltself may be operated at atmospheric pressure, or at much lower pressures, by maintaining a suit ably reduced pressure in the receiver 24. For this purpose the vacuum pump 48 and the condensate pump 49 are provided for exhausting uncondensed vapors and gases and condensed distillate respectively, from the distilling system. Where the operation 1s carri-ed out as a batch operation upon successive charges of oil with separation of the distillate into progressively heavier cuts, reduced pressures may be employed' with advantage for eliminating light undesirable constituents from the lubricating oil fractions, and'in carrying out the process of the invention the lubricating oil distillate can be separated into narrow fractions by regulating the operation of the still, of the fractionating tower, and of the treating tower in accordance with the invention.

The process of the invention is of general application to lubricatin oil-containing oils and distillates. It may ie applied to crude petroleums or to topped crude oils from which lighter constituents, such as asoline, have been stripped. It is also applicable to the treatment of other oils and residues containing lubricating oil constituents, such as crude lubricating oil distillates and fractions.

It may be employed in the treatment of oils of either asphaltic or parafiine base or mixed base oils. Following the distillation and relining treatment of the present invention, the lubricating oil distillate fractions may be ltered through fuller-s earth or similar material or subjected to such other treatment ,is may be desired. lVax containing distillates, for example, may be subjected to suitable de- Waxing operations in the usual manner. In referring to lubricating oils herein, reference is made to the petroleum oils characterized by oiliness and high viscosity'. In general these oils may be defined as oils made up of constituents heavier than gas oil, having a gravity lower than about 35 Be. and a Viscosity upwards of about 50 at 100o F. Saybolt universal.

I claim:

1. An improved method of distilling and refining lubricating oils, which comprises vaporizing lubricating oil constituents from a body of oil containing lubricating oil constituents, subjecting the lubricating oil vapors to treatment with alkali solution withdrawn from an extraneous supply of caustic alkali solution, withdrawing condensate and associated alkali from the alkali treatment, returning condensate and associated alkali from the alkali treatment together with fresh caustic alkali solution from the extraneous supply of caustic alkali solution to the alkali treatment, and condensing the vapors from the alkali treatment to obtain a lubricating oil condensate.

2. An improved method of distilling and refining lubricating oils, which comprises vaporizing lubricating oil constituents from a body of oil containing lubricating oil constituents, subjecting the lubricating oil vapors to treatment with a caustic alkali solution, withdrawing condensate and associated alkali from the alkali treatment, returning condensate and associated alkali from the alkali treatment together with fresh caustic alkali solution to the alkali treatment, and condensing the vapors from the alkali treatment to obtain a lubricating oil condensate.

In testimony whereof I aflix my signature.

GEORGE H. TABER, JR.

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