US2029687A - Continuous process for counter current contacting of two liquids - Google Patents

Description

Fb. 4, 1936. R. E. WILSON ,0

;CONTINUOUS PROCESS Fox COUNTER CURRENT CONTACTING OF TWO LIQUIDS.

liled Dec. 178, 1931 @B gmmw Patented Feb. 4, 1936 PATENT orrlcsj CONTINUOUS PRCCESS FOR COUNTER CUB RENT CONTACTING OF TWO LIQUIDS Robert E. Wilson, mm, m., assignor to Standard Oil Company, Chicago, 111., a corporation of Indiana Application December 18, 1931, Serial No. 581,927

10 Claims.

' p This invention is concerned with an improved method for-the counter-current contacting of two immiscible or partially miscible liquids.

One object of my invention is to provide a process wherein oneliquid may be passed over the surface of another liquid moving in the opposite direction, the two liquids being intimately contacted with each other and thereafter con- 1515111611813 and eflicientlyseparated from each er.

Another object of my invention is to provide g a suitable apparatus for carrying out this process.

Further objects of my invention will become apparent as the description thereof proceeds.

The nature of the invention will be made more apparent by reference to the accompanying drawing which illustrates one embodiment of it and in which: 0

Figure 1 is a longitudinal view partially in cross section and Figure 2 is a vertical section taken along th line 2--2 of Figure 1.

In the drawing ll refers to a substantially horizontal casing preferably of approximately U-shaped section having near the bottom of one end an inlet pipe l2 and near the top of the same end an outlet pipe i 3. At the other end, thecasing i I is provided with an upper inlet pipe I! and a lower outlet pipe i5 which may suitably be located at the bottom of a sump l6 formed by an extension of casing I I. The cas-.

ing is equipped to carry a longitudinal shaft il extending throughout the whole or a portion of its length and carried-by suitable bearings or journals l8 and IS. The shaft I1 is equipped to be rotated by suitable means, not shown, operating upon gear or pulley 20. The shaft I'I carries at various points in its length paddles 2 I.

The casing 2| is partially divided into sections by baiiles 22, which in a preferred form extend inwardly from the casing leaving a substantial opening around the shaft l1. Baiiles 22 may suitably be provided with holes or valves, not shown, located near the point at which they join the lower portion of the casing, thereby making ratus, being removed by means of outlet pipe It.

The original liquid having the higher specific gravity is introduced through inlet l2, impinges against baflle 24, flows through the apparatus and out through outlet pipe I5.

Although my process and apparatus will be found useful in a large number of cases in which it is desirable to contact two liquids continuously, it will be found to be of particular value in the selective extraction of lubricating oils by means of special solvents. It is known that when lubricating oil fractions are submitted to the solvent action of such materials as nitrobenzene, phenol, and dichlorethylether, the more naphthenic, and therefore less desirable, portions of the oil are dissolved, whereas the more parafllnic, and therefore more desirable, portions remain undissolved. In the past it has been usual to conduct such processes by raising the temperature of the sol vent and oil until complete miscibility occurs and then lowering the temperature until a separation takes place. This process is time-consuming and requires large and expensive equipment. Furthermore, the extraction accomplished is less complete than when using my counter-current process. Another method of accomplishing these results has been to operate at a single temperature by merely agitating one or more batches of solvent and oil together and then allowingthem to separate. This procedure is also time-consuming and requires unwieldy equipment. Furthermore, it'does not accomplish as satisfactory a separation of the'constituent fractions of the oil as does my method. This fact is quantitatively illustrated in a specific instance described hereinafter.

The process of my invention operates continuously and accomplishes better resultsthan the former methods in less time and at less expense.

Furthermore, my process can be accurately controlled.- For instance, since the equipment is small it is relatively very easy to keep the temperature at the optimum point by lagging or jacketing the casing ll. Fm'thermore, the degree of agitation to' which the two liquids are subjected can be delicately controlled by controlling the rate of rotation of shaft IT, for instance by means of a variable speed motor or variable reduction gears, not shown. I

Furthermore, fresh incoming solvent will first come in contact with the oil which has been" ble of dissolving but the most readily extractable constituents will still dissolve in the nearly spent solvent. This makes certain the maxi- I mumpossible utilization of the solvent power of the solvent and permits economies of time and material. In other words, by the use of my process and apparatus, the oil is extracted quickly, thoroly and efiiciently to give the best possible fractionation into relatively paraflinic and relatively naphthenic constituents.

It will be understood that in the intermediate portion of my apparatus: that is, in the com-- partments formed by baiiies 22 and containing the paddles 2|, the two liquids will be agitated together in order to assure good contact and to bring about eflicient extraction. However, the rate of rotation of shaft I! must not be suffi ciently high to produce thoro emulsification, since this would prevent the counter-current flow of the two liquids. The rate of rotation of shaft I! will therefore be as high as is consistent with satisfactory operation. Any emulsion which may be formed in the intermediate portions of the apparatus will separate out in the end portions prior to withdrawal of the final liquids. to enhance this separation process, the casing II ispreferably tilted at a slight angle from the horizontal, thereby causing the'interface 25 of the two liquids to assume a slight angle to the axis of. the casing. This has the effect of providing a relatively deep layer of the heavy extracted liquid at the end where that liquid is being withdrawn 7 be gradually admitted to my apparatus thru pipe I! while one hundred barrels of an acid-treated mixed base lubricating fraction having an S. A. E. number of 20 are being admitted thru pipe I. The paddles 21 may be rotated at a moderate speed and the dichlorethylether together with extracted oil may be withdrawn thru pipe l5 while the residual .oil together with some dissolved dichlorethylether is withdrawn thru pipe I3. The solvent may be removed from each of-these two products by distillation. On examination it will be found that the original oil hasbeen fractionated into two very diiferent materials having the following properties as compared with the original oil:

Illl order temperature with the same amount of dichlorethylether, allowed to settle and the solvent removed, the properties of the residual oil would compare as follows with the properties of the residual oil produced by my process:

My new .fifiiit.

Viscosity at 100 265 Viscosity at 210 F 48' 48 Resistance to sludging Excellent. Fair.

Although my invention has been described in conjunction with a specific embodiment thereof,

it is to be recognized that many modifications can be made without departing from the spirit thereof. For instance, casing ll maybe of any desired form and may be provided with other types of baflle equipment to suit the exigencies of the particular case.

As an example of another possible modification it is to be understood that outlet pipe I 3 could conveniently be replaced by a weir. 'It will furthermore be readily comprehended that in the event serious emulsification .difliculties are encountered the end sections of the apparatus may be suitably enlarged or extended. Under other circumstances itmay be desirable to elongate the central portion of the apparatus in order to achieve more thoro contacting and greater utilization of the counter-current features of the process.

Baflles 22 may be of other forms. The form shown is highly suitable in many cases, since the liquids passing from one section to the next must pass near the shaft at intervals, thereby assuring that only the most thoroly contacted portions are'passed on to the next compartment.- Other forms of baflie including perforated plates, may be'suitably used, in some cases. Additional baflles may be added.

Altho the present invention has been described in connection with the details of a.speciflc embodiment thereof, it is not intended that such details shall be regarded as limitations upon the scope of the invention, except insofar as included in the. accompanying claims.

I claim:

1. A process for the solvent extraction of lubricating oils in a series of zones arranged in an approximately horizontal lineal relationship to each other and comprising two end zones and a plurality of intermediate zones, said process comprising admitting a stream of lubricating oil at a point near the end of one of said end zones, flowing said stream thru all of said zones. in succession, admitting a stream of solvent near the end of the Original 011 Residual oil Extracted oil Yield- 10Q 30%. Nature"; Mixed base Relatively pal-amnion Relativelynaphthenic. Viscosity at 100 F 306 sec. Saybolt 228 sec. Saybolt Highly ;viscous and Viscosity at 210 F 50 sec. Saybolt 48 sec. Saybolt sticky. Resistance to sludging Poor Excellent Notflsnuitailile as lubrica g o It will thus be seen that by the use of my process a poor lubricating oil may be made to yield 70% of an excellent lubricating oil, resistant to sludging and having a very low temperature coeificient of viscosity. This process is much more efficient than simple agitation and settling. To illustrate this: if the same amount of this same original oil is thoroly agitated at the same end zone opposite said last-mentioned end zone, flowing said stream of solvent thru all of said zones in succession in a direction. opposed to the direction of flow 'of said stream of lubricating oil, and in continuous contact therewith, continuously partially commingling said stream of solvent and said stream of lubricating oil throughout said intermediate zones as thoroly as possible without producing substantial permanent emulsification, separating said partially commingled streams in each 01' said end zones and separately removing the two resultant liquids from opposite 5- end zones.

2. A process for the solvent extraction of a mixed baselubricating oil fraction with a solvent comprising dichlorethylether, said process comprising flowing a stream of said solvent. thru a 1o plurality of contact zones. flowing a stream of said of lubricating oil in the contact zones intermediate oi the end contact zones and separately withdrawing from opposite end contact zones, a resultant liquid comprising the major portion of said solvent containing in solution a minor portion of said lubricating oil,said minor portion comprising the relatively naphthenic constituents of said lubricating oil, and removing from the end zone opposite said last-mentioned end zone a re- 'sultant liquid comprising a minor portion of said solvent and a major portion of said lubricating oil,

said major portion comprising the relatively paraflnic constituents of .said lubricating oil.

3. A process for contacting a liquid with a second liquid partially miscible with said first-menao tioned liquid in a series of zones arranged in an approximately horizontal lineal relationship to each other and comprising two relatively quiescent end zones and a plurality of intermediate zones, said process comprising admitting a stream ,of said first-mentioned liquid into one of said end zones, flowing said stream through all of said zones, in succession, admitting a stream of said second liquid into the end zone opposite said lastmentioned end zone, flowing said stream of said 40 second liquid through all of said zones in succession in a direction opposed to the direction of flow of said stream of said first-mentioned liquid and in continuous contact therewith, continuously partially commingling said stream of said flrst mentioned liquid and said stream of said second liquid in said intermediate zones as thoroughly as possible without producing substantial permanent emulsilflcation, separating said partially commingled streams in each of said end zones and separately removing the two resultant liquids from opposite end zones.

4. In a process for the continuous counter-current contacting of a lubricating oil stock and a solvent selected from the class comprising nitrobenzene, phenol and dichlorethylether in a series of partially segregated contact zones, the steps which comprise coagitating said stock and said solvent in each of said contact-zones intermediate the end contact zones but not in said end contact zones and restraining the passage of the 55 said stock and said solvent in each of said contact zones to pass to the next successive contact zone;

5. A process for the continuous countercurrent contacting of two liquids in a series of zones arranged in an approximately horizontal lineal relationship to each other and comprising two end zones and a plurality of intermediate zones, said process comprising admitting a stream of one of said liquids into one of said end zones, flowing said stream through all of said zones in succession,

admitting a stream of the other of said liquids into the end zone opposite said last-mentioned end zone, flowing said stream of said first-mentioned liquid through all 01 said zones in succession in a direction opposed to the direction of flow of said stream of said second-mentioned liquid and in continuous uninterrupted contact therewith, continuouslymartially commingling said two streams throughout said intermediate zones as thoroly as possible without producing such thoro emulsification as to interfere with countercurrent flow, separating said partially commingled streams in each of said end zones and separately removing the two resultant liquids from opposite end zones restraining the passage of all but the most thoroly commingled portions of said two streams from passing from zone to zone.

6. A process according to claim 5 in which said two liquids are an oil and a selective solvent.

7. A process according to claim 5 in which said two liquids are a lubricating oil stock and a selective solvent for the relatively naphthenic portions of said stock. I

8. A process according to claim 5 in which said two liquids are a lubricating oil stock and dir chlorcthylether.

9. A process for the continuous counter-current treatment of a lubricating oil stock comprising relatively parafllnic constituents and relatively naphthenic constituents in a series of contact zones arranged in substantially horizontal linear relationship to each other and comprising twoend contact zones and a plurality of intermediate contact zones, said process comprising admitting a stream of said lubricating oil stock. to one 01' said end contact zones, flowing said lubricating oil stock through all of said contact zones in succession, admitting a selective solvent for said relatively naphthenic constituents to the end contact zone opposite said flrst mentioned end contact zone, flowing said selective solvent through all of said contact zones in succession in a direction opposed to the direction of flow of saidlubricating oil stock and in continuous contact with said lu bricating oil stock, continuously partially commingling said selective solvent and said lubricating oil stock throughout at least some of said intermediate contact zones substantially as thoroughly as possible without producing substantial emulsiflcation in the topmost and bottom-most strata, and separately removing the two resultant liquids from opposite end contact zones.

10. A process for the continuous counter-current treatment of a mineral lubricating oil stock comprising 'relativel" paraflinic and relatively naphthenic constituents with a selective solvent comprising dichlorethylether, said process comprising flowing a stream of said selective solvent through a series of contact zones comprising two end contact zones and a plurality of intermediate contact zones, flowing a stream of said lubricating oil stock through the same series of contact zones in a direction opposed to the direction of flow of said stream of said selective solvent, partially commingling said two streams in said intermediate contact zones, .and separately withdrawing from opposite end contact zones two resultant liquid phases comprises respectively the bulk of said selective solvent together with said relatively naphthenic constituents and the remainder of said selective solvent together with said relatively parainnic constituents.

ROBERT E.-WILSON.

CERTIFICATE OF CORRECTION.

Patent No. 2,029.687. February 4, 1956.

ROBERT E. WILSON.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 5, first column, strike out lines 28 to 51 inclusive comprising claim 3; same page, second column, line 12,, claim 5, before the word "separating" insert the words and comma restraining the passage of all but the most thoroly commingled portions of said two streams from passing from zone to zone, and in line 15, same claim, beginning with the word "restraining" strike out all to and including the word "zone", line 18; same page and column, line 69, claim 10, for "comprises" read comprising. I I

The claims now appearing in the patent as numbers 4, 5, 6, 7, 8, 9 and 10 should bear the numbers 3, 4, 5, 6, 7, 8 and 9 respectively; and that the said Letters Patent should. be read with these corrections therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 7th day of April A.. D. 1936.

Leslie Frazer I v Acting Commissioner of Patents.

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