US2176983A - Art of refining - Google Patents

Description

091.24, 1939. 9 G, mAYER 2,116,983 ART oF REFINING AFiled Aug. '6, 1957 2 sneetssneet 1 INVENTOR GEORGE 75ans?? BY fw/m', "www ATTORNEYS 0a. 24, 1939. G, `THAYER y 2,116983 ART OF REFININGv Filed Aug. 6, 1937 i 2 SheetS-Sheelt 2 l 54W Jaz rf/vr JJ Zw/MWM @VM ATTORNEYS Patented Oct. 2.4,v 1939 UNITED STATES vPATENT :OFFICE l Sinclair corporation oi' Maine panyyNew York, N. Y., a

Application August 6, 1937, Serial No. 157,748

3 Claims.

This invention relates to thetreatment oi' hydrocarbon oils and more particularly to the solvent extraction of lubricating oils. The process of this invention provides .an improved and efl iicient method of contacting hydrocarbon lubricating oils with a selective solvent.

Heretofore, solvent extraction of hydrocarbon lubricating oils has been effected by thoroughly agitating the oil and solvent under suitable-conl ditions of temperature and pressure in a mixing chamber and subsequently separating the extract and raiiinate phases in a separate operation. Such a process as this has necessitated?l large amount of apparatus for mixing the oil and solvent and for separating the extract and ramnate phases.

vIt has also beenproposed to eii'ect solvent extraction of lubricating oils by introducing the solvent and untreated oil into the top and bottom, U respectively, of a bailled tower. As a further modification, solvent extraction of the oil has been effeciiedb'yl introducing the oil into the central portion of saivrtical tower and introducing a heavy solvent 'into the top and a light solvent l into the bottom of the tower. In such operation the mixture of oil and solvent or solvents com- `pletely iills the entire space within' the tower, and contact between solvent and oil is effected by countercurrent flow of the solvent or solvents 0 and oil due to their relative diierence in gravity. Where gravity towers such as these have been used it has usually been necessary for satisfactory results that a plurality of towers be arranged in series in order that the nal raflinate be suill- 35 ciently refined. Whenever it has been necessary to repair or to clean any one of the gravity towers the operation of the entire series has been discontinued, thus resulting in an obviously uneconomical use of a large amount of equipment.

40 The process of my invention provides a simple and eiiicient operation whereby satisfactory separation may be effected in a single stage using a simple and extremely compact apparatus as compared with apparatuses heretofore necessary.

45. By the use of the process of my invention, a solvent extraction plant constructed with a number of these compact machines operating in parallel would not have its capacity seriously handicapped if one or even more of the machines were shut 50 down for cleaning.

More particularly, the process of my invention contemplatesv subjecting the oil to be treated and a suitable solvent or solvents to. the action of centrifugal force to produce an extract and a ramnate phase, and withdrawing the extract and l ramnate phases. 'Ihe oil and the solvent or solvents may be separately introduced into a centrifuge. ,The extract and raiinate phases produced within the centrifuge by the contact between the oil and solvent upon subjection to cenl trifugal force may be separately withdrawn from the centrifuge. l

The process of my invention will be more clearly understood by a consideration of the apparatus in which the process iscarried out. A l typical form of apparatus is shown in Figure 1 of the accompanying drawings which comprises a sectional view of a centrifuge in which an oil may be subjected to selective extraction;

Figure 2 comprises a sectional view of a modu ified form of centrifuge; and

Figure 3 comprises a horizontal sectional view of the stationary and revolving bowls of the centrifuges.

, The centrifuge shown in Figure 1 comprises a 20 stationary bowl I provided with a cover divided radially into two non-communicating chambers- 2 and 3. A revolving bowl 4 provided with a cover member 5 is positioned coaxially within the stationary bowl and is rotatably mounted therein.' Two sets of concentric cylinders 6 and 1 are placed within the revolving bowl 4, and these sets of concentric cylinders are positioned so as to alternately overlap each other, thus forming a series of annuluses. One end of one set of 3" cylinders is rigidly mounted in the false bottom 8 of the revolving bowl and one end of the other set of cylinders is rigidly mounted in the false cover I 0 of the cover member 5. Suitable means maybe provided on the inner surface of the false cover I0 and of the false bottom 8 of the revolving bowl for removably holding the unmounted ends of each of the sets of concentric cylinders securely in position. The unmounted ends of the cylinders are provided with suitable perforations 40 I I and I2 to allow the passage of a iiuid therethrough. Perforations I3 and I4 are provided in the false cover and false bottom, respectively,

of the revolving bowl to permit the passage of l a fluid from the interior of the revolving bowl into the space between the false cover and false bottom, respectively, and the outer shell of the revolving bowl, which space is maintained by perforated spacer rings I5 and I6, respectively. 'Ihe centers of the false cover and the false bot- :.0 tom terminate in concentric cylinders I'I and I8, respectively, which extend into the cover portion of the stationary bowl. An additional cylinder I9 extends coaxlally from within the cover portion of the stationary bowl between cylinders Il 25 vIn carrying `out theprocess and I8 to a position well within the interior of the revolving bowl.- Cylinder I1 communicates with the upper section 2 of the cover portion of the stationary bowl while cylinders Il and I9, re- 5 spectively, communicate with suitable supplyv pipes 20 and 2I. The desired space between the concentric cylinders I1 and I8 and between the concentric cylinders I8 and I8 is provided by perforated vspacer rings 22 and 23, respectively. 10 The collar 24 of cover member 5 extends within section 3 of the stationary bowl cover portion and provides a communicat g space, together with cylinder I1, for uid tol ss from thespace maintained by spacer rings Ik into section 8. Discharge spouts 25 and 28 are provided for the removal of fluid from each of sections 2 and'3 ofl the cover portion ofthe stationary bowl. Supply pipes and 2I may be provir'jed withl advantage `with valves (not shown) for'controlling the rate of flow of liquid through these pipes. Suitable means may be provided .with advantage for draining from,l the space between stationary bowl I and revolving bowl l any fluid which may have vleaked thereinto.

A of my invention, inthe apparatus shown in Figure 1, the oil to be treated is introduced linto the centrifuge throughA 35' cylinders I8 and I9- through spacer rings 23 and into the central portion of'the interior of the revolving bowl. 'I'he 'revolving bowl is rotated by means of sha' 21 thus exerting centrifugal force on the oil and solvent. The solvent, being heavier Q0- than the oi displaces the oil at the outer portion of the revolving bowl and forces the oil toward the center of the bowl. As the oil is forced toward the center ofthe bowl, it passes through a tortuous'path as it ows through the annuluses 4,5V and the perforations II and I2 alternatelyposi ltioned at the top and bottom, respectively, of adl.jacent concentric cylinders 8 and 1. Thus, the oil` being forced` toward the center of the bowl "edge ofV thebowlcome intol contact as they pass throughl the; v anuulusea' -The.sclvent,;as it apkl proa'cli'es Ythe outer edge ofthe revolving bowl,

`comprises a solution ofthe extract inthe solvent,4 l while lthe oilforced toward the center of the bowl" comprises-,the rened oil or'raillnatephase. The

-positiorii "of the interface, i ,which `is indicated by j v ,the.fdo'ttedline- 28,.between the oil and theextraetv phasesinftlre outer portion of thev revolving bowlx 1 f isjoontrolled with advantage by the internal-dii.

` arneter'of ' replaceableringidams 28 and 29?." The "'positifon' ofthe interface isv moved towardtlie -'ameteiL-of ring` dam 29; or, conversely; is-'moved f ff"-towdtheiouterportion,of-.the bowl-.by increase yingfthe-intermal-diameter'of ring 29.V Varia-U tiouln-fthe. -internai'uiameter or ring-damas'. has

- a diametrically lopposite eifectuponthe position ofthe irrtferface toithatl of ringdam` 28.] The l l positionfo the interface' may, therefore. beson-j* 10 trolledbychanging. the internaldiameter of 'ring dani-zsjgrzs'., bythe ombmed enel-.t o! both.l

Theoil beingforcedltoward-the center.` by the yextract phase tends to fill thergreater portion of the-bowl.` The heavier solvent, or' extract phase" L u as it becomes, fiowingcounter-cmrentlyoutf ,the apparatus.

and thesolvent, being forcedtoward the outerv` mumble supply pipe' 35 WhtcIrJmw bg prow-laA r with a. suitable valvinotshownl".

icehterf ofthe bowl by decreasing. the internal" di ward with respect to the voil flows upward or downward, as the case may be, .on'the outer edge of each annular space seeking .its yway to the outer portion of the bowl.' At the lip 'of each cylinder, formed by the perforations II and I2, the out- 6 flowing solvent (or extract) phase and the inflowing oil (or ralnate) phase Vundergo instantaneous mixing and are separated again by centrifugal force in 'the next succeeding annular space. and instantaneous mixing, each annular space with the lip of the cylinders within the revolving bowl comprises a stage in a counter-current system. The extract phase collected' at the outer portion of the revolving bowl passes through per- 15 forations I3 through spacer rings I5 into section 3 f of the cover portion of the stationary bowl. The

extract and raiiinate phases are discharged fromA The modined form of apparatus .shown in Figure 2 is adapted for use in aprocess wherein the oil to be treated is subjected to-the actiongof two individual selective solvents. The apparatus itself is substantially the sameas that shown in n Figure 1. The modified apparatus, however, is provided with an additionalcylinder extending coaxially within cylinder t8 and conforming generally to the shape of cylinder I8 and false bottom 8 of the revolving bowl. The lower extension 35 3l of the cylinder 80 engages at its outermost end the false bottom 8 at a point substantially half way between the center and outer portion of the revolving bowl. The false bottom is further provided with perforations 82 to permit the o passage of a i'luid into the interioil of the vre.. volving bowl from the space between the lowerextension 8| and false bottom"8.'"This space'be- .tween lower extension 8I and false bottom 8fis maintained by perforated spacerrings 33, while `In outthe processavofmyiinvention in v -the'vmodied' form of'apparatus shcwnin Figure a, v.the-.011m be treated isintrodued mtdthe centrifuge. through supply pipe- 28'.' into vthe-fs'r'iacef "between-fv cylinders l" I8 and 1,88, thence? 55a spacerrings .34 and fandiperforations.32into the bowl substantiallypmalfway. between the center and outergportionfthereoh-*A'heavy sol- .Y

`vents'uch, for example;as phenol. may be introe. f

f duced through supplypipe2l Aandspacer rings 28. 60.

- .into the l{center portion of` `.the 1' -revolving bowl.

A suitableV light solventgsucijnasj valighff -Iiaphtha "or' tli'e like iszintroducedthroughsupply. pipe "85.8.

f intojcylinderll, lthence.through spacerrings-Il` l and perforationsll into'ithe'outermt portion of 55 f therevolving bowl. r` Uponrotationofthe revolvf l' 'ingbowl by means of martina centrifugal fpre g of considerable magnitude; maybe "exerted upo'n.k

thegcill and solvents withinlth'e bowl.' The heavy 'solvent is'forced toward the outerportion of the 70 revoli'rin'g-bowl vtogether 'withither heavy ,extractl i obtained from the oilbyccntactlbetween the o ilVv and the solvents.' Theflighter solvent .isdislj placed from' theouterfportion 'of the-revolving` l .bowl and is toward'the' center-of thefbowl w As' a result of this counter-current flow 10v together with the ramnate tional speed of the revolving bowl.

produced by contact of the oil and solvents-#The extract ows through perforations I3 and spacer rings I5 into section 3 of the cover portion of the stationary bowl, while the raffinate is forced upwardly through spacer rings 22 into section 2 of the cover portion. If desired, the entire apparatus may be maintained under a superatmosphericl pressure by enclosing the apparatus in a4 suitable pressure chamber. Thus, the modied operation carried out in the apparatus shown in Figure 2 comprises a process in which the oil to be treated and'two individual solvents are introduced separately into a centrifuge and separate extract and raffinate phases are discharged from the apparatus.

If it is found desirable to maintain a substantially uniformrevplving speed of i'luid within the apparatus shown in Figures l and 2, the rotatable bowl may be provided with a plurality of vertical radial partitions 36 These vertical radial partitions may extendsub'- stantially the entire distance between false bottom 8 and false cover I0 of the rotatable bowl and also extend substantially the entire distance between cylinder IS and the outer shell 4 of the revolving bowl.

-While the -process of my invention has been described above With respect to the treatment of unrened oil, it must be emphasized that my invention is also applicable to the treatment of an oil which issaturated or partially saturated with a solvent. Y" For example, if a plurality of centrifugal machines are to be connected in series so that the raiiinate from the flrst machine is introand subsequent machines will comprise a reiined or partially refined oil containing a substantial quantity of solvent or solvents. Moreover, it may be desirable, under certain conditions such as the relative densities of the oil to be treatedv and the solvent or solvents, to mix the raw oil with one or more of the treating solvents, or even a diiierent solvent, before introducing the raw oil into the machine. In such a case, the mixture of raw oil and solvent or solvents charged into the machine as stock to be treated would have a substantially higherfdensity than that of the raw oil alone, power consumption required to maintain the rota- Therefore, the expressions oilj and. oil to be treated appearing in the specification and claims should be interpreted as including an oil saturated or partially saturated with one ormore solvents. I As a further modification,

the heavyA solvent COmDrises phenol or nitrobenzene, for example.

Many advantages are realized from the use of the process of my invention. complete separation of the extract and raiiinate if l as shown in Figure 3.

thus effecting a decrease in.

Y mediate that of the the apparatus shown An elcient and produce a highly eiiicient mixing of the oil and solvent.

The compactness and simplicity of the centrifuge conserves space and simpliiies the opera.- tion as well as cleaning of the apparatus.

Moreover, inasmuch as the process of this invention thoroughly mixes the oil and solvent and eiliciently separates the extract and raiiinate phases, the treatment with a single machine may constitute with advantage the complete treatment of the oil. A solvent plant using the process of this invention carried out in a number of centrifuges operating in parallel, therefore, wouldA not be seriously handicapped With respect to its overall capacity if one or even several machines were shut down for cleaning or repairs.

I claim:

1. In the solvent extraction of hydrocarbon lubricating oils, the improvement which comprises introducing a selective solvent into the central portion of a centrifuge, introducing an additional selective solvent into the outer portion of the centrifuge, introducing the oil to be treated into the trifugal force to produce an extract and a ramnate phase, and separately withdrawing the extract and raiinate phases.

2. In the solvent extraction of hydrocarbon lubricating oils, the improvement which comprises introducing a relatively heavy selective solvent into the'central portion of a centrifuge, introducing a relatively light selective solvent into the outer portion of the centrifuge, introducing the oil to be treated into the centrifuge at a point intermediate the points of introduction of the selective solvents, subjecting the oil and solvents to the action of centrifugal force to produce an extract and a raiiinate phase, and separately withdrawing the extractfand raffinate phases.

3. The method of securing counter-currentcontact between a relatively heavy duid, a relatively light-duid, and a fluid having a density interheavier` and lighter fluids which comprisesintroducing the heavier iiuid into the innermost of a plurality of laterally closed passagewaysfof increasing radius, said passageways having non-aligned openings, introducing the lighter :duid into the introducing the uid of intermediate density'into a passageway intermediate the innermost and loutermost passageways, and rotating the passage- Inasmuch as the outermost passageway,y

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