US2113010A - Reactivation of oil decolorizing mediums - Google Patents

Description

Apnl 5,` 1938. c, F. TEARS REACTIVATION OF OIL DECOLORIZING MEDIUMS Filed Aug. 4. 193e CLAUDE Ff TEARS' mvEN-roR AT ORNEY Patented Apr. 5, 1938 I uNlrl-:oysrATEs PATENT OFFICE REACTIVATION F OIL DECOLORIZING MEDIUMS` Claude F. Tears, Warren, Pa., assignor to The Petroleum yProcesses Corporation, Wichita, Kans., a corporation ofi'Kansas Application August 4, 1936, Serial No. 94,161

8 Claims. (Cl. 252-2) This invention relates to the reactivation 0f solution of oil in the solvent the mixture is the mediums employed for the deoolorizing 0f shown as passing through line 8 to a heater 9. lubricating oils and is a continuation in part of The heated solution may then be passed through the Tears application, Serial No. 679,073, Patent line I0 direct to the iilter II or it may iirst be 2,067,802, Jan. 12, 1937. passd by line Ill-I2 through cooler I3 and The conventional method of reactivating thence by line I4-I0 to the filter, the cooling fullers earth and like decolorizing mediums is by thus effected enabling operation at lower presroasting. The expense incurred in the transfer s'ure. Valves I5, I6, I1 in the lines connecting to and from the roaster and the resultant losses the heater and cooler and the lines'connecting lo are considerable. with the ilter enable such control to be exercised 10 Special objects of this invention are to avoid and, if desired, the sending of the llow partly such expenses and lcsses and to get a greater through the heater and partly through the cooler eiiciency in the reactivated material than has in series with the heater. been possible by such prior methods. It has been found that the most desirable These particular objects and other desirable filtering temperature is in the neighborhood of 15 objects are attained in the present invention by v 125 F., but acceptable results can be obtained the novel features of invention hereinafter dewithin the temperature range of 60 F. to 200 F.' scribed, illustrated and broadly covered in th Since the solvent is normally gaseous, it is ClaimS- necessary to maintain pressure on the entire 'The drawing accompanying and forming part mixing and filtering system suflicient to keep 20 of the specication illustrates diagrammatically the solvent in the liquid state. 'I'his is effectedv one preferred embodiment of the invention, but it in the illustration by a regulatable valve 49 in will be understood that structure and steps of the flow line I0 leading to the lter, which maint-he process may be modied, as conditions retains a desired back pressure on the mixing, quire, all within the true intent and broad scope heating and cooling system and valve 44 in the 2'5 of the invention. discharge lino la from the bottom of the nner The invention involves reactivation of the demaintains a desired pressure in the illter.

colorizing medium by color removing solvent. In The ltered or decolorized oil solution passes the prior Tears application No. 679,073, above through line I8 to the still I9 through a heater referred to, trichlorethylene was disclosed as be- 20 where it is heated to vapor'ize` the solvent. 30 ing particularly eiective in vremoving coloring The major portion of the solvent is vdistilled off matter, oil, or carbon from a propane treated in still I9 and leaving at the top by line 23 is conl clay and' for reactivating such clay. It has been densed in condenser 24 and under control of found that methylene chloride (dichlor-methane valve' 25 returned through line 26 to the storagel CHzClz'is especially effective as a color removtank 2. 35

ing solvent and reactivating agent. Chloroform Pressure of approximately 200 pounds per (CHCla) also has been used with success. These, square inch is maintained on the still by control as well as the general class, of the chlorinated of valve 25 and heat for distillation is shown as hydrocarbon compounds, are peculiarly eiective applied by means of a heating coil 41 inthe base solvents for color-removal and reactivation. of the still. From thebottom of the still the 40 To illustrate the process, reference is made to partially denuded, decolorized oil ows by line 2| the accompanying diagram, which is in the nato a stripper 48, which is provided with a heatture of a ow sheet showing basically the pering coil 50 and is operated at low pressure, for cclation method of decolorizing first ydisclosed in instance on the order of 15 pounds per square 45 the above-identified earlier Tears application inch. At this pressure all the remaining solvent 45 and involving the ltering of lubricating oil in may be distilled ofi through line 5I, connected solution in a normally gaseous, liquefied hydroto the suction side of the compressor 32, which carbon. latter serves to compress the-solvent vapor for In this particular illustration, the oil to be recovery by condensation in the condenser 33.

decolorized is taken from storage tank I and the Back pressure is maintained in the condenser by 60 normally gaseous liquefied hydrocarbon, such as manipulation of vvalve 53 and the recovered solpropane, under pressure, and in the liquid state, vent in liquid form returns to the solvent storis taken from a suitable holder 2, pumps 3 and 4 age tank 2 through lines I4-26.' A valve 'I0 is conveying the same under pressure through lines shown provided in a bypass 'Il about the com- 55 5 and 6 into a mixer l. To promotecomplete presser. 55

When the decolorizing clay becomes exhausted and therefore useless as a decolorizing medium, the oil is rst washed out of the clay by pumping fresh solvent under pressure from pump 4 through line 29, with valve 28 open and valve 21 closed, directly into the top of the iilter. This fresh solvent passes down through the clay and washes out the oil retained by the clay. This filter Wash is passed over through line I8 to the still I9 for recovery of the solvent.

'Ihe next step is to remove the solvent from the clay for recovery. This may be accomplished by heating the bed of clay by means of the internal heater 30 and vaporizing the solvent through line 3| directly to the condenser 33 by opening the compressor bypass 1l at the valve 10. This distillation may be continued so long as solvent can bev thus removed and at the end of such timethe compressor bypass is closed at valve 10 and valve 50a is opened to vent the lter to the suction side of the compressor. In this operation all solvent is removed from the clay by low pressure distillation. After all the solvent has been thus removed, the clay is ready for reactivation by Washing ,with the color-removing solvent.

The color-removing solvent is transferred by pump 62 from tank 35 through line 36 to the filter. Valve 44 at the bottom of the filter is closed and valve 31 in the line 45 leading to the still 38 is opened so that the solution of coloring matter in the color-removing solvent passes to still 38, vbeing heated on the way by heater 46. Additional heat is supplied in the illustration by heater 46a in the base of the still. As the colorremoving solvent is distilled off, the color-bearing constituents are removed at the bottom.through line 39 and cooler 40. Such material may be diverted to a storage tank, not shown.

The overhead vapor from still 38 may be directed through line 63 to condenser 56 to be condensed and returned through line 64 to tank 35, or it may be passed through the reflux condenser 51 to be condensed and returned hot to the lter for the removal of additional coloring matter. When the reiiux condenser is used in this way it is preferable tohave a portion of the vapor stream passing through the nal condenser 56 and back to the color-removing solvent storage tank 35.

Washing with the color-removing solvent is continued until the stream from the base of the filter is colorless, indicating complete removal of the color-bearing constituents from the decolorizing medium. It then becomes necessary to recover the color-removing solvent. This may be accomplished by dlstilling it from the decolorizing medium directly to condenser 56 through the valved bypass 59 around the reflux condenser 51, heat for such distillation being supplied by heating coil in the filter.

Distillation of the color-removing solvent is continued until all such solvent is removed from the decolorizing medium. In some cases it may be desirable to remove .the last traces of colorremoving solvent from the decolorizing medium by Washing such medium with fresh, normally gaseous liqueed hydrocarbon from tank 2. When this washing step is employed the liquefied hydrocarbon solvent is passed on into still 38 from which it is distilled overhead through line 63-58 directly to condenser 33 by opening valve 60 and closing valve 6l. Experience has shown that only a relatively small amount of the colorremoving solvent is Washed out of the decolorizing medium by'this normally gaseous, liquefied hydrocarbon wash. The small amount thus removed may be accumulated in the base of still 38 and removed by distillation through condenser 56 when the still 38 is next used for recovery of color-removing solvent.

Decolorizing medium, such as 30-60 mesh fullers earth may bereactivated at least six times using methylene chloride in the manner described and the reactivated clay has a relative eiiiciency of above as compared' with new fullers earth. This is considerably higher than the efficiency of fullers earth reactivated under the present methods of roasting.

After about six reactivations under this invention the eiciency of the decolorizing medium decreases rather rapidly. Apparently such sudden drop in decolorizing efliciency is due to failure of the methylene chloride to completely re- Amove all the color-'bearing compounds retained by the decolorizing medium. To furthenuse the medium it then becomes necessary to employ a second color-removing solvent which will remove those compounds not removed by the methylene chloride. A desirable second solvent for such purpose is a mixture of 50% benzol and 50% methanol.

Alfter reactivating the decolorizing medium some five or six times with methylene chloride, it may be washed with this second, benzolmethanol mixture to reactivate it for use again. In the illustration, the benzol-methanol mixture is supplied from tank 65 and line (i6- 36, by pump 62 to, the filter and returned after recovery to the tank by line 64-61.

The process has been described above in connection with `percolation filtration of a solution of lubricating oil in normally gaseous liquefied hydrocarbon. While the use of normally gaseous liqueed hydrocarbon solvent is highly desirable ln the operation of the present process, it isv not entirely essential and the reactivation need not necessarily involve the Washing with normally gaseous liquefied hydrocarbon solvent before and after washing with the, color-removing solvent. Other oil solvents may be used for removal of oil from the fullers `earth and for the removal of the color-removing solvent from the fullers earth.

The present solvent reactivating process may be employed also for reactivation of contact ltering mediums, such as iine fullers earth, or some of the chemically treated decolorizing clays. Such contact filtering operations may be conducted With the oil in solution in a normally gaseous liqueed hydrocarbon solvent, in naphtha as a solvent, or the oil may be contacted hot without the use of any solvent. In all such contacting operations it is usual to filter out the contact clay in `a iilter press, the clay being retained on the lter plates. A convenient means of reactivating such contact clay under the present invention is to Wash it in place on the filter plates with the color-removing solvents here disclosed. The clay can then be dried in place in the filter, or may be removed from the filter and dried elsewhere, being then ready for use again.

As an example of the effectiveness of the present method, ordinary, ne fullers earth was used .for contactfiltering a solution of Pennsylvania steam-retined stock in naphtha at a temperature of F. with three pounds of the ne fullers earth per gallon of steam-reiincd stock in the solution. This resulted ina color of 8 N. P. A. after the naphtha was removed from the deform until the color of the chloroform indicated removal of no more color constituents. vThis same clay was used ve times after such reactivation and under the same filtering conditions it was found that there was no distinguishable differences in the color of the nished oil from the ve fltrations.

'I'he present invention avoids the costly handling and transfer between the filter and roaster and saves the losses heretofore occasioned by such handling. Furthermore, the emciency of the medium reactivated by this solvent washing is much higher than the same medium reactivated by the roasting. The invention may be practiced by relatively simple additions to and modification of present equipment. r

I claim:

1. 'I'he herein disclosed process of reactivatlng adsorbent decolorizing medium, which comprises washing the same with methylene chloride.

2. The herein disclosed process of reactivating adsorbent decolorizing medium,l which comprises washing the same with' methylene chloride and 'thereafter washing said medium with a mixture 'washing the same with a color-removing solvent of the chlorinated hydrocarbon class and then washing the medium with normally gaseous liqueed hydrocarbon while maintaining sufficient pressure to hold the normally gaseous liquefiedhydrocarbon in a liquid state.

5. The process of reactivating decolorizing medium, which comprises washing the same with a color-removing solvent of the chlorinated hydrocarbon class, then washing with a mixture of benzol and methanol and finally washing with a normally gaseous liquefied hydrocarbon under pressure suifcient to maintain the solvent in the liquid state.

6. 'Ihe process of reactivating decolorizing medium, which-comprises washing the same with methylene chloride, washing with a benzolmethanol mixture, and then washing with a liquefied normally gaseous hydrocarbon under pressure sufficient to maintain the solvent in the liquid state to remove traces of both previous washes.

7. The process of repeatedly reactivating adsorbent decolorizing medium, which comprises washing said decolorizing medium after each use with chlorinated hydrocarbon solvent until such washing fails'to restore the decolo'rizing eiliciency of the adsorbent medium and then washing said medium with'a mixture of methanol and benzol, which will remove the color compounds irremovable by'the chlorinated hydrocarbon and thereafter washing with a liquefied normally gaseous hydrocarbon under suflicient `pressure to maintain the same in a liquid state.

8. The process of reactivating decolorizing medium which comprises washing it rst with a liqueed normally gaseous hydrocarbon under pressure suflicient to maintain the same in a liquid state, then washing with a chlorinated hydrocarbon and thereafter washing with a liquefied normally gaseous hydrocarbon under pressure suiiicient to maintain the same in a liquid state.

' v CLAUDE F. TEARS.

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