US1891402A - Method of treating oils - Google Patents

Description

De'c'- 20, 1932- F. L. cRAlsE ETIAI. 1,891,402

METHOD OF TREATING- OILS Filed sept. 5, 41928 En TER. J4

f/L TER SEPAMTHR HEAT Exam/mfr? NEJTEXcf/mn MPHLEEHHTO BRIGHTENEW mmm wgrm Patented Dee 2o, 1932 UNITED c STATES PATENT oFFlcE FRED' L. GRAISE, OF EL SEGUNDO, HOWARD G. VESPEB AND HUBLEY G. GRIFFITH,

OF INGLEWOOD.'CALH'OBNIA, ASSIGNOBS T0 STANDARD OIL COMPANY 0F CALITOB- NIA, OF SAN FRANCISCO, OALIFORNIA, A CORPORATION F DELAWARE mamon or 'riesame ons Application led September 5, 1928. Serial No. 804,090.

This invention relates'to a method of treating animal, vegetable,marine or mineral oils for purifying, decolorizing and brightening such oils. The invention particularly relates 5 to a method of removing cloudiness from oil, and in rendering such oil bright and clear, not only at high temperatures, but also at any predetermined low temperature. The

invention also relates to a continuous method 1o of treating oils with adsorbents and in treating the oil during such process ofA decolorization and purification with adsorbents so that the finished product is clear and bright at low temperatures.

i In treating oils such, as, for example, mineral oils, with adsorbents such as fullers earth, finely divided decolorizing clays, acid treated clays, or other adsorbents, it is customary to mix the oil to be treated with the 2 adsorbent, heat the mixture if so desired, and then remove, or separate, the oil from the adsorbent. The word adsorbent as used herein includes all decolorizing agents such as those listed above, and any others of similar nature and action, and the word adsorption refers to the action of such decolorizing agents on the oil.

In the manufacture of lubricating oils and other mineral oil, it has been found that even "though the oil treated with an adsorbent is clear and bright at the relatively high temperatures used during the adsorption step proper, such oils after having been separated from the adsorbent and cooled, generally become cloudy.

' It has been discovered that the clouding of various oils, upon being reduced in temperature, is caused by the presence of suspended 40 and dissolved moisture in the oil. The solubility of water in the oil increases with increasing temperatures so that'oils which may be bright at elevated temperatures, but which are saturated with water at that tem cloud upon cooling by reason of precipitation rature,

from solution of minute water drops throughout the oil.

An object of this invention is to disclose and provide a method whereby oils may be rendered bright and clear at any predetermined low temperature.

Another object of this inventlon is to provide a simple and effective method of removing cloudiness from oils.

An object of this invention-is. to' disclose and provide a .method -of treating mineral oils whereby the oils may be steam-sweetened and rendered bright and clear when cooled to any predetermined low-tem erature. Another object of'this inventlon is to provide a method whereby oils may be treated with adsorbents, sweetened and brightene in acontinuous manner.

Other objects and advantages of this invention will be apparent from the following detailed decription of one preferred meth of carrying out the invention and the particular sequence and character ofsteps em braced in the body, it bein understood that v the invention is'not limited to the `preferred method described in detail but embraces va- `rious modifications and alternative steps or operations, some of which are hereinafter describedsuch alternative steps or methods being apparent to those skilled in thevart after considering the disclosures made herein. y

For purposes of illustratiomreference shall be made to the appended diagrammatic illustration of a complete process for treating oils, and particularly mineral oils, with an adsorbent and for sweetening and brightening the oil.

The apparatus for carrying out the inven-l tion may comprise, as illustrated in the drawing, a mixing tank 1, preferably rovided with a conical bottom-.2, and a va ved discharge line-3 leading from the lower portion of the tank 1 to a circulating um 4. The tank 1 may be supplied with oil to treated from a suitable source (not shown) by means 9o` of a valved feed -line 5. Adsorbents may be lsupplied to tank 1 in any suitable manner and in any suitable form, for example, in dry,

finely divided condition, or in the form of a 5 thick oil-adsorbent or water-adsorbent suspension, mud, or slime. For purposes of illustration, adsorbent may be supplied to tank 1 from a hopper, or tank, 6, provided with a suitable controllable outlet.. A suitable. mixing device may be provided in tank 1.

The discharge line 7 may be provided with a by-pass line8 and valve 9 whereby all, or a portion, of the oil discharged by the pump 4 may be returned to tank 1 for circulating, mixing, or other purposes. The main pipe line 7 is provided with a valve 10, preferably leading to a'feed pump 11, then leads to a heat exchanger 12 in which the oil, or mixture of oil `and adsorbent, may be preheated. From the heat exchanger 12, the oil-adsorbent mixture may be carried by linel 13 to a heater of any desirable construction and size such, for example, as a heater 14 provided with a bank of tubes 15 and a combustion zone 16.

The oil-adsorbent mixture, after passing through the bank of tubes 15, may be discharged by line 17 into asteam separator 18 provided with a valved vapor outlet 19. The mixture of oil and adsorbent maythen be returned by a line 20 from thevsteam separator 18 to a second bank of tubes 21 in the heater 14 (or to a separate heater if desired), and, after being raised in temperature to the desired degree, discharged therefrom by a line 22 through the heat exchanger 12, and by a line 23 into a suitable brightening, steamsweetening, or other, apparatus.

In the form of apparatus shown in the drawing, the mixture of oil and adsorbent is discharged byline 23 into the upperportion of a combined sweetener and brightener 24, which may take the form of a vertical cylindrical tank provided with centrally disposed conical distribution plates 25, and alternate annular plates 26. Means, 27, for introducing steam or substantially inert gas, from a valved supply line 28 into the brightener 24, may be provided.' Vapors from the brightener 24 may be discharged into a dephlegmating or refluxing zone or chamber 29 -provided with a cooler, 30, supplied with cool- 'ing Huid. A vapor discharge line 31 from the7 dephlegmating Vchamber 29 may leadlto suitable condensers and' which are not shown.

The oil discharged from the lower portion of the brightener 24 may be carried by line 32 to a booster pump 33,'` and forced thereby through line 34, through a heat exchanger 35 an line 36 into a suitable separating mechvacuum pumps, 55

anism such as a filter 37. The oil from ilter '37, discharged through line 38, may then be passed through a cooler such as the heat interchanger 39, and discharged therefrom by line 40 to storage, or further treatment. The

heat interchangers 35 and`39 may be supplied with water, or other fluid, so as to establish flow of cooling liquid therethrough counter to the flow lf oil through such coolers. Supply line 41, line 42, and discharge line 43 indicate means for passing cooling fluid through the coolers 35 and 39.

The operation of the process in the above.

described apparatus will now be described.

Oil to be treated may be introduced to the mixing tank 1, either continuously or intermittently, but preferably in a continuous manner, and mixed ,therein with aI suitable adsorbent, such as a decolorizing and adsorbing clay, supplied to the tank 1 from tank or hopper 6. The condition and the quantity of the adsorbent, added to the oil, may differ materially, depending upon operating conditions, type of oil, the effect desired, and other considerations. The mixture of oil and adsorbent is then sent through heat exchanger 12 where its temperature may be raised to 150 to 400 F. The mixture may then be sent through the heater 14, and particularly, bank of tubes 15, where it is raised in temperature to above 250 F.

If the heat exchanger'12 is capable of rais-v adsorbent mixture through the bank of tubes 15 can be eliminated.

The heated mixture of oil and adsorbent may then be passed into a separator 18, preferably maintained at a super-atmospheric pressure, and the major portion of water mechanically held in the oil (in suspension in the oil) and some of the water held by the adsorbent is released and removed from the mixture of oil and adsorbent in the form of steam or vapor. The partly dehydrated oil may then be brought up to a desired adsorption, or contact temperature, by passing the o il through a' heater, say the bank of tubes 21 in heater 14. When lubricating oils are be- ,ing treated, the temperature' of the oil-adsorbent mixture discharged from bank 21 by line 22 may be from about 450 F. to about 750 F., although temperatures appreciably differing from this range'may be used under certain conditions'. The -1 oil may then be cooled somewhat'by passage through the heat exchanger 12 where its heatfis transferred in part to the incoming mixturegthe use ofsuch p cooling step, and of th'e'heat "exchanger-12,

the mixture of oil and adsorbent discharged v from line 23 is then treated to remove a major portion of water dissolved and suspended in the oil. The greater portion of Y suspended Water was removed in separator 18 but an excessive quantity of dissolved water is present in the oil, it being remembered that the solubility of water in oil increases with temperature. The water content of the oil should be reduced to below the saturation content corresponding to any predetermined lower temperature, say 80 F., 40 F., or even lower.

This reduction may be accomplished at any temperature ybetween the maximum and minimum Vtemperatures of the operating cycle (between 150 and 750 F., as stated hereinabove), but it is preferably carried out at a sufiiciently elevated temperature to in-A sure a reasonably high vapor pressure of the water (as above 250 F.) but at a low enough temperature to prevent substantial vaporization of the oil, unless it is desired to also remove the light products of cracking often created' during the contacting period at high temperatures. The latter object, removal of cracked constituents, may be accomplished separatelyas by steam-blowing the oil after contact with adsorbent, but before brightening by removal of water in solution.

The brightening operation may, in accordance with our invention, be preferably accomplished by theyk use of vacuum, although it may 'be accomplished by any means for reducing. the partial pressure of the water vapor` below the vapor pressure ofthe water in solution, as by blowing with air, inert gas such as carbon dioxide, or application of vacuum. If the separator 18 is maintained at super-atmospheric pressure (as notedabove) then the oil in line 23 will be under pressure and at a high temperature, and such oil entering brightener 24 will have its pressure materially -reduced, thus facilitating vaporization of contained water, even though the brightener 24 is not maintained under vacuum. Furthermore, the brightening operation can also be carried out by cooling the oil to a low temperature so as to precipitate the water from the solution, and then filtering, the adsorbent being removed either at that time or by a preceding filtration. The latter filtration method is not particularly desirable, however, and the process will be described as carriedl out by the application of vacuum in conjunction with a sweetening operation to remove odors and light constituents resulting from a high temperature contacting. Blowing with air is somewhatundesirable for some oils owin to a chemical action of the oxygen upon theot oil. Blowing with inert gases is slightly more expensive owing to the cost of supplying the inert gas and of dehydrating andpreparing the wet gas for recirculation.

In operating by the use of the apparatus disclosed in the drawing, the mixture of oil 4and adsorbent is discharged into a vacuum tank or brightener 24, preferably equip ed with suitable baiiie plates or the like so t at a large surface area of the mixture of adsorbent and oil is exposed. Steam may be supplied to the lower portion of the brightener 24 for sweetening purposes so as ,to re` move odoriferous constituents created during a high temperature contacting in the bank of tubes 2l of heater 14. v

The brightener 24 is maintained under a suitable vacuum, the degree ofvacuum` depending u on the temperature of the mixture of oil an adsorbent being supplied. to the brightener and upon the degree to which the water content of the oil must be reduced. The water vis removed from solution in the oil and discharged from the brightener 24 into a dephlegmator 29 wherein petroleum oil constituents vaporized during this operation -may be recondensed and return to the brightener 24.

The steam, undesirable constituents resulting from the effect of the adsorbent upon the oil, and the water vapors, pass through the dephlegmator 29 and are discharged through the vapor .outlet 31 which leads to suitable condensers and vacuum pumps utilized in maintaining a desired vacuum upon the brightener. The oil, after such sweetening and brightening process, may then be immediately filtered, or otherwise treated, so as to separate the adsorbent therefrom, or Y as shown in the drawing, the oil may be first cooled partially, then filtered and lthen cooled to a suiiiciently low temperature to enable it to be sent to storage.

This invention is not to be limited to aprocess such as is described in detail hereinabove, it being understood that numerous changes and modifications may be made without departing from the invention. It is to .be distinctly understood, for example, that the brightening operation need not vbe carried out in conjunction with a. sweetening operation as numerous oils may not need a sweetening operation to be performed thereon. Furthermore, the process isnot t', be limited to the exact sequence or steps of operations described as the particular process hereinabove described is merelyy illustrative of a complete contacting proces'sitof treating` oils in which the brightening operation forms a single step. For example, the voil may-'be treated with an adsorbent, the adsorbent removed, and the water content of the oil then reduced to below the saturation content of water which would exist in the oil at a, predetermined low temperature.

Obviously the brightening process may be made a part of numerous other processes of 5 treating oil where it is desired to produce a clear, bright oil which will remain clear when cooled to a low' temperature. The removal of dissolved water from the il need only be carried out to a suiicient extent t0 reduce .the water content -below saturation' conditions at'a predetermined low temperature.

1. In a process of producing bright oils,

the steps of mixing an 'oil to be treated with an adsorbent, heating the mixture under pressure, partially releasing the pressure on said heated oil mixture to permit vaporization of a portion of water contained in said mixture, removing such vaporized Water,

again heating said mixture to above 250 F,

and reducing the Water content of the heated oil to below the saturation content of water which would exist in said oil at a prede- ,termined low temperature by reducing the pressure to subatmospheric to reduce the partial pressure of the water vapor below the vapor tension of the water in solution in the oil being treated.

2. In a process of producing bright loils,

the steps of mixing an oil with an adsorbent,

heating the mixture to above/250 F. under pressure, partially releasing the pressure on said heated oil mixture to permit vaporization of a portion of water contained in said 1 mixture, f removing such vaporized water,

again heating said mixture to above 250 F.,

then subjec-tlng the mixture of oil and adsorbent to subatmospheric pressure to reduce the water content of the oil to below the wav4,0 ter content' which would exist in said oil at saturation condition at a predetermined low pressure, and finally separating the adsorbent from the treated oil and cooling the oil.

Signed` at El` Segundo, California, this 22nd day of August, 1928.

FRED L. CRAISE. HOWARD G. VESPER. 5o i HURLEY G. GRIFFITH.

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