US1746915A - Apparatus for refining oil - Google Patents

Description

Feb. 11, 1930. G. H. TABER, JR

APPARATUS FOR REFINING OIL Filed Dec. l5, 1928 Mw. um

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ATTORNEYS "Patented Feb. 11, 1930 UNITED STATES PATENT olii-ICE GEORGE H. TABER, JB.; F RYE, NEW YORK, AssIGNoR To SNCLAIR REFNING couramncr NEW Yonx, N. Y., A CORPORATION 0F MAINE APPARATUS FOR BEFINING OIL original application led January 14, i925, Serial No. 2,262. Divided and this application led December 15, 1928. Serial No. 326,218.

This invention relates to improvements in apparatus for the distillation and. refining of lubricating oils. The invention provides an improved apparatus for producing lubricating oils from oils and distillates containing lubricating oil fractions, such as crude petroleum oil, topped crude oil, and crude lubricating oil distillates. This application is a division of an application filed January 14,

1925, Serial No. 2,262. Y

Hitherto, in the art of producing lubricating oils from crude oil, the crude oil has been initially subjected to a'fractional distillation, either by batch operationsor in a series of continuo-us stills, and a broad lubricating oil distillate fractionthereby separated from the crude oil; and this lubricating oil fraction has then beensubjected to redistillation in the presence of caustic alkali introduced directly into the body of oil undergoing distillation for the production of refined lubricating oil distillates, the caustic alkali solu' tion being employed toremove undesirable" constituents such as naphthenic acidsand asphaltic compounds which ifallowed todistill over with the finished lubricating o1l distillates wouldrender them bad colored and,

ditlicult to handle in further treatment. It has been proposed to apply the caustic alkali treatment directly to the crude oil undergoing distillation durin the time in which the broad lubricating oil raction was being produced, but such proposals have not been successful principally because of excessive deposition Within the still due to the accumulation of caustic alkali in the residuum and to the combined effect of such caustic alkali and impurities normally present in the crude oil. The apparatus of the present invention, as applied to the production of lubricating oils, provides for vaporization of the lubricating oil fractions from the crude lubricating oilcontaining oil or distillate, treatment of thel vaporized lubricatingoil constituents with a caustic alkali, and recovery of the treated lubricating oil constituents.

In applying the apparatus of the present invention to the production of lubricating oil, the vaporized lubricating oil constituents 53 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 phase. 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 treatmentv of the lubricating oils with caustic alkali can be eliminated. Moreover, the refining operation, when carried out in this Way, has several other important advantages. Thorough and intimate contact between the caustic alkali andthe lubricating oil can be 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 also may be combined advantageously with fractionating operation for separation ofthe desired lubricating oil fractions. The elimina tion of a distilling operation, particularly the crude distillation as ordinarilycarried out, also assists in eliminating crackedvproducts 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 followlng description. v

n the operation of the apparatus of the present invention, the lubricating oil fraction may be vaporized from the crude oil or crude lubricating oil distillate iI a vaporizing still and this vaporization may be efccted under atmospheric pressure or it may be eiected under a subatmospheric pressure. The va-4 porization may be carried out with or without f the introduction of steam or an inert gas. One advantageous way to carry out the vaporization is with the introduction of steam and under reduced pressure. After vaporizal tion, the vaporiaed lubricating oil constituentsmay be subJected to a fractionatingoperatlon, for example, by passing the vapors without being returned to the still. Where afractionating tower is employed in connection -with the vaporizing still, the crude oil or crude lubricating oil distillate may be introduced into the' tower an'd employed as a reluxing agent therein; and the operation of the tower and vaporizing still may be con'- trolled so that vaporization of the desired lubricating oil fraction from the crude material introduced into the tower is substantially completed in the tower.

From the vaporzing still, or from the fractionating tower connected with the vaporizing still, the vaporized lubricating oil constituents are conducted to a treating tower in which they are subjected to treatment with caustic alkali. In the treating tower, the lubricating oil vapors are thoroughly and intimately contacted with a caustic alkali solution. The treating tower may be ofy conventional bale tower construction arranged for introduction of the vapors into the lower part of the *tower and of the treating solution into the upper part of the tower so that the lubricating oil vapors are contacted in counter current iow with the caustic alkali solution. In the treating tower, a part of the oil vapors are condensed and the condensate mingles with (the used treating solution.

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 sutlicient to remove the undesirable constituents from the lubricating oil vapors being treated, but the maximum amount employed may vary widel as will appear hereinafter. For example, t e rate of introduction into the treating tower of the sodium hydroxide solutions just referred to may vary from 1/2% to 15% or more on the weight of vapors entering the treating tower. An excess of the caustic alkali solution, over that required to effect the desired refining operation, does not injure the quality of the lubricating oil distillate fractions produced, but such an excess c of treating solution may produce an increased cooling effect in the tower with the condensation of an increased proportion of the vapors therein. Condensation within the treating tower. may be regulated by controlling the amount of treating solution introduced therein. Where an aqueous solution of caustic alkali is employed Iin the treating tower, part of the water may be evaporated from the solution in the tower 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 caustic alkali in oil in admixture with a more or less concentrated solution of caustic alkali.

By Yappropriately regulating the cooling.

effected in the'treating tower, for example by controlling the amount of treating solution circulated through the tower, la lubricating oil distillate fraction may be separated from the vapors in the treating tower. A lubricating oil fraction may similarly be separatcd 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 oilvfraction, free from the lighter vapors which escape through 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 `trolled fraction can be separated in the treating tower, heavier constituents being removed from the vapors 1n the fractlonating 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 treating tower may be thoroughly lagged to prevent heat loss and the treating solution may he preheatedbefore introduction into the treating tower. In this manner, the treating tower operation can be controlled so that only heavier constituents are condensed therein and so that only a minimum proportion of such heavier constituents are condensed. Any lubricating oil constituents condensed in the treating tower may be separated from the tower condensate mixture and recovered.

The uncondensed vapors escaping from the treating tower are condensed, for example in an ordinary water cooled condenser. Where the mainportion of the lubricating oil frac- Y heavier constituents an tion 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 con dense a minimum proportion of the lubricating oil Jfraction, the condensate from the vapors escaping from the treating tower comprises the lubricating oil distillate fraction. lhere the vaporized constituentsy escaping from the still., or from the ractionating 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 ractionating operation, however, may be controlled so that the final condensate produced from the vapors escaping from the treating tower is the desired lubricating oil distillate fraction.

Before the vapors escaping from the treating tower are condensed, they may be sub- /jected yto a further ractionating operation. They may', for example, be passed through a second fractionating tower in which the desired lubricating oil fractions are condensed and through which the constituents lighter than those desired in the lubricating oil fractions arelallowed to pass uncondensed. Such a second ractionating 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 treatin tower to condense by regulating the operation of the second ractionating tower ltopermit lighter constituents to escape uncondensed therethrough.i Where such a second ractionating tower is employed, a heavier lubricating oil fraction may be separated in the treating tower and a lighter lubricating oilfraction, which tower is free from the lightest undesirable constituents, can be separated in th fractionating tower.

The apparatus of the present invention consists of a series of continuously operating vaporizing stills in which a series of progressively heavier fractions are treated for the separation of progressively heavier distillates, or through which the crude oilor crude lubricating oil distillate is successively passed oseveral distillation stages.

with vaporization therefrom of progressively heavier fractions in successive stills of the series. The oil component of the condensate mixture separated in towers operating on lighter vapors is introduced into treating towers operating on heavier vapors wlthvnnprovement of the fractionation effected in the The caustic alkali associated with the oil in the condensate mixture from preceding treating towers may obe introduced with the oil into successive treating towers and employed for treatment l of the heavier vapors therein, or the caustic alkali component of the condensate mixture may be separated and fresh alkali supplied to successive treating towers.

The invention will be further described in connection with the accompanying drawing which illustrates Yin a diagrammatic and con-- lso comprises three stills, it will be apparent that a greater or lesser number could be employed for the separation of a greater or lesser number of fractions. In the three stills shown, the same parts are designated by the same reference numeral, with c appended in the second still 5, and with d appended in the third still 5d.

The apparatus for the separation of the, j

irst cut or fraction comprises a vaporiz'ing still 5, a fractionating tower 6, a treating tower 7, and a cooler and condenser 8. The still illustrated is of the direct re heated type. The still is provided with a charging'line 11 and a residue draw-oit 12. The ractionating tower 6 is arranged above the still. This tower is provided with a helical balile 13 and the vapors from the still pass upwardly through the helical passage in the tower escaping from the upper end of the tower through the vapor line 14. Connection 15l is arranged near the upper end ofthe tower for .the introduction oi charging stock into the still through the tower.

From the vapor line 14 Athe va ors enter i the treating tower 7, the tower shown being of conventional baile construction, and pass upwardly therethrough about the bailles 17 arranged in the tower.r -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 2O arranged in thev upper end of the tower. The vapors rising through the treating tower escape through the vapor line 21 to the condensin coil 22 from whichcondensate is discharge into conventional look-boxes and receivers. The treating solution is supplied to the pump 18 through connection 31, which communicates with tank 32 through connection 33 having valve 34 therein. The condensate mixture collecting in thev lower part of the treating tower 7 is discharged through connection 38 to the tank 35. A separation of condensate and treating solution may be ef- V:t'ected in thetank 35. The oil condensate is lighter than the admixed caustic alkali nsolutionand tends to float thereon; and connection 46 is provided for withdrawing separated oil from the upper layer collecting in the tank and connection 47 for withdrawing lused caustic solution from the lower layer. A

separation may thus be eli'ected in the tank 35 between the oil and the used caustic solu- -tion of the condensate mixture, and as much of the used\ caustic solution as may be desired may be employed in the next treating tower together with fresh caustic solution from the tank 76.

The exposed parts of the still 5 and the fractionating tower 6 and the vapor line 14 are advantageously heat insulated or lagged to prevent unnecessary heat loss. Where it is desired to pass the maximum amount of and the ractionating tower 6 and the treating tower 7 are suitably constructed and reinforced to prevent collapse under the excess of atmospheric pressure prevailing o n the 'outside over the reduced pressure w/itlnn the distilling apparatus, and suitable precautions are taken to prevent inleakage of air. The

' several vapor connections andthe passages through the fractionating towers and treating tower are also made of suihcient'crosssectional area so that the desired degree of vacuum can be maintained without excessive consumption of power. For maintenance of subatmospheric pressures within -the distilling system, a vacuum pump is arranged beyond the receiver and look-box and suitable valves and pumps are arranged where needed for pumping liquid against the vacuum. g

A connection 7 0 including a pump 71 1s provided for :withdrawing residual oil from the'still 5 and introducing it into the tower 6 on the still 5, and a connection 7 2 includingy a pump 73 is provided for withdrawing residual oilv from the still 5 and introducing it into the tower 6d on the still 5*". A connection 74 is provided for supplying the treating solution to the treating tower 7 through thev pump 18 and the connection 19-, and a connection 75. is provided for supplymg the `treating solution to the treating tower 7.

The connection 74 is; arranged to withdraw fresh caustic alkali-solution from tank 76 through connection 77 and to withdraw from the tank 35 either condensate mixture through connection 33 or the separated -oil component of the mixture through connection 46. The connection 75 is arranged' to withdraw fresh caustic alkali solutionfrom taining 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. The

supply of additional charging stock throughy connection 15 may be regulated to control the reluxing operation in the fractionating tower. The fractionating operation is regulated Y so that the desired lubricating oil constituents escape fromthe 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 countercurrent 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 is fresh solution from the tank 32.

For the separation of a lubricating oil fraction in the treating tower, the circulation of treating solution through the tower is regulated to effect condensation therein of the desired lubricating oil constituents. The condensation effected by the treating solution, and by evaporation of 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 1the condensate mixture `is circulated through the next treating tower the condensatemixture may be cooled by circulation throughlthe cooling coil 41 on its way to the tank 35. After separation from the used caustic solution in the tank 32, the lubricating oil fraction condensed in the treating tower7 may be withdrawn through connection 46, and may be subjected to further settling or washing treatment or other suitable treatment or the separation of any remaining admixed caustic alkali.

For circulating the main portion of the lubricating oil vapors through the tower with 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 treating solution entering the'treating tower 7 through the nspray-head 20 may be preheated. The lubricating oil vapors escape from the treating tower through the vapor line 21 and are condensed and collected. Where the operation is '6 the feed of additional lubricating oil-conf carried out continuously in this manner, the condensate may include, in addition to the lubricating oil constituents, some lighter constituents which ma be removed by further treatment. Any lubricating oil constituents condensed in the treating tower collect in the tank and may be withdrawn therefrom aftef separation from the caustic alkali solution therein.

The apparatus relates more particularly to operations in which fresh oil is supplied to' the vaporizing still and residualI oil withdrawn therefrom and in which a fraction of substantially' uniform character is separated.- The apparatus of the vpresent 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 constitu-l ents 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 ifV the pressure in the receiver is approximately equal to atmospheric pressure the pressure in the still will be somewhat greater due to the resistance 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 inventidn the lubricating oil distillate canbe 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.

A series of progressively heavier charging stocks maybe separately supplied to the several stills either through connections 15, 15c and 15d or through connections- 11, 11, and 11d the latter particularly where no fractionating tower v'is employed; or a lubricating oil-containing charging stock may with advantage be supplied to the vaporizing still 5, after vaporization of lighter components the heavier residual oil pumped to still l.5", and after vaporization of another fraction in still 5 the heavier residual oil pumped to still 5".

In the secondtreating tower the caustic alkali solution may include used alkali from the condensate mixture tank or fresh caustic alkali solution or a 'mixture of the two. In the apparatus illustrated, separate fresh alkali solution tanks are shown for each treating tower, but where vonly a single strength of treating solution is used only a single supply tank is necessary. More concentrated treating solutions may be used in the treatment of the heavier vapors; and, where the used alkali solution from the treatment of lighter vapors is employed in admixture with fresh alkali solution in the successive treatment of heavier vapors, the concentration of the composite alkali solution may be adjusted by regulating the concentration of the fresh i caustic solution admixed therewith. For example, water may be evaporated from the alkali solution in the treating tower and this more concentrated' solution can bebrought to the proper degree of concentration for further use in a following treating tower byv admixing a relatively dilute caustic alkali solution therewith. In successive treating towers, treating solutions similar to v those used in the second may be employed.

The oil component of the condensate mixture separated in the treating towers is introduced into a successive "treating tower through which vapors heavier than those in the treating tower in which it is formed are passing. The treating tower operation is controlled to separate heavier constituents, those heavier than desired in the particular cut, from the lubricatinor oil vapors passing therethrough, and thesezheavier constituents are introduced intoa successive treating tower where heavier lubricating oil vapors areundergoing treatment. In the successive tower the introducedoil is employed to proinote separation of heavier constituents from the vapors therein in a similar way and the introduced oil is itself fractionated, the constituents corresponding to the desired cut being vaporized 'and escaping from the treating towers with the other vapors. The fractionation is thus improved. This is particularly advantageous where no fractionating tower is employed between the ,vaporizing still and the treating tower. y

The oil component of the condensate mixture may thus be separated from the admixed used alkali solution and employed in admixy ture with fresh alkali solution for introductionvintov a successive treating tower, or the condensate mixture itself, including the usedv alkali, may be directly introduced into a successive treatin tower, either alone or with the addition o fresh alkali. The oil component of the treating tower condensate mixture from the last still in the series may be subjected to further simple distillation, advantageously in the presence of an alkali, which alkali may be the used alkali component of the condensate mixture or fresh vcaustic alkali.

The apparatus of the invention is of general application to the production of lubricating oils from lubricating oil-containing oils and distillates. It may be applied to crude pctroleums or to topped crude oils from which lighter constituents, such as gaso- 'l manner.

line, have been stripped. It is also applicable to the treatment of other oils and residues containing lubricating oil constituents, lsuch as crude lubricating oil distillates and fractions. It maybe employed in the treatment of oils of either asphaltic or paraiine base or mixed basey oils. Following the distillation and relining treatment of the present invention, the lubricating oil distillate fractions may be ltered through ullers earth or similar material or subjected to such other treatment as may be desired. Wax containing distillates, for example, may be subjected to suitable dewaxing operations in the usual 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 delined as oils made up of constituents heavier than gas oil,having a gravity lower than about 35 B.` and a viscosity upwards of about 50 at F. Saybolt universal.-

yI claim:

An apparatus for the production of lubricating oils comprising a series of stills'eachy provided with, a fractionating tower adapted to receive the vapors from the still, a treating tower connected to the ractionating tower and adapted to receive the vapors therefrom, a condenser connected to the treating v tower and adapted to receive the vapors therefrom, and a cooler adapted to receive the condensate from the treating tower, means for supplying fresh caustic alkalito at least one treating tower of the series and means connected to the associated cooler for delivering at least a part of the condensate therefrom to a succeeding treating tower of the series.

In testimony whereof I aix my signature.

GEORGE H. TABER, JR.

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