US1769766A - Method of producing lubricating oils - Google Patents

Description

July 1, 1930. w BRYANT 1,769,766

METHOD OF PRODUCING LUBRICATING OILS Filed Dec. 10, 1926 2 Sheets -Sheet 1 Fig.1

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July 1, 1930. w BRYANT 1,769,766

METHOD OF PRODUClNG LUBRICATING OILS Filed Dec. 10, 1926 2 Sheets-Sheet 2 &

E w 94 w \Z. b '3 51 4,50 EF /it [uh 0/37.L 5 I Patented July 1, 1930 UNITED STATES PATENT OFFICE WILLIAM '1. BRYANT, F HOUSTON, TEXAS, ASSIGNOR 'I'O W. A. WILLIAMS, OF

. HOUSTON, TEXAS METHOD 0]? PRODUCING LUBRICATING OILS Application filed December 10, 1926. Serial No. 153,944.

This invention relates to an improved process of producing lubricating oils from crude mineral oils.

The previously commonly used practice for producing lubricating oils from crude mineraloils is to distill ofi the lower boilin fractions, includin the gas oil fraction, an

i then make sever cuts of higher boiling 1 fractions from which lubricating oils are obm tained by further distillation and refining. These higher cuts may be classified as the light out, the medium cut, and the heavy cut with the final bottoms. Each one of these cuts is generally re-distilled to produce a bot- I tom product and an overhead distillate. The

overhead distillate in each case is then generally refined to produce a lubricating oil. The refining usually consists in treating the oil with sulfuric acid, alkali, and water, as

is well known in the art.

At this point the oil may be bright and may not require any further treatment, except what is known as the blowing bright process to be subsequently described. The product at this state is an unfiltered pale or red oil.

It has also been common practice to decolorize and purify lubricating oils by means of various cla s, as, for example, fullers earth. The lu ricating oil is treated with the cla usually after the acid treatment or after the oil has been subjected to both the acid and alkali treatments. After the acid treatment or after the acid and alkali treatments, the lubricatingoil is transferred from the agitator into a mixing tank where it is agitated in contact with fullers earth or other similar clay. The mixture of clay and oil is then either filtered cold or the mixture is heated by various methods. The clay is then separated from the oil by passing the mixture through a filter of the Sweetland, Kelly, or other form of pressure filter. The oil from the filter is then blown bright, by which is meant that the oil is run into an open top, rathershallow tank, having perforated air pipes "in the bottom, and air is blown through the oil, the purpose of this procedure being to remove the moisture still remaining" in the oil and also remove any low-boll ng fractions which may be mechanically or otherwise held in the oil (the removal of these low-boiling fractions increasing the flash point'of the finished oil). From this tank the oil is delivered to a storage tank for finished oil.

According to this invention, instead of treating each of the high lubricating oil cuts separately, as has been the practice heretofore, the entire lubricatin oil cut, which is taken off after the gas oil action, is treated as a whole. The crude mineral oil is distilled in the usual way, taking oif the usual lighter fractionsincluding the gas oil fraction, the distillation taking place in the presence of steam and inert gas. The distillation is then continued until only the bottomsremain in the still. The amount of the bottoms is usually 5% to 10%. The entire condensate recovered from this continued distillation is the raw material which is treated by the process of the present invention. This condensate is generally of low viscosity and naturally contains some relatively low-boiling fractions. The entire condensate is run into an agitator, where it is treated with sulfuric acid and the sludge is drawn off. The amount and strengthof sulfuric acid varies, depending upon the oil under treatment and the product which is desired.

Due to the fact that the oil under treatment is of relatively low viscosity, the refining thereof with sulfuric acid is very much simplified. This oil contains not only constituents of high viscosity, but also constituents of lower viscosity.

Heretofore, in order to refine the heavy cuts of high viscosity which resulted in the distillation processes heretofore used, it has been necessary to blend these viscous cuts with low-boiling hydrocarbon oils such as naphtha, kerosene, or gas. oil, before it was possible to effectively treat with acid and alkali; Blending is necessary in order to prevent emulsification during the acid and alkali treatment which involves agitation.

After the blended mixture has been refined with acid and alkali, it is necessary to remove by distillation prior to the clay treatment, the oil which has been used for blending.

The oil remaining after the lighter portions acidtreatment has been separated, the oilmay then be treated with alkali in the usual way; Preferably, however, no alkali is used.

The oil is then treated with a clarifying and decolorizing agent. such as fullers earth, diatomaceous earth, or a similar clay. The clays used are preferably such as have been ground to ap roximately 200 mesh, although a coarser or ner clav may be used. The oil and clay are preferably mixed in continuous flow as the oil passes from an agitator or a source of supply into a suitable still. In this still, which is heated externally, the oil and clay are continually agitated by means of an inert gas such as steam which is injected at the bottom. In this still a considerable portion of the lower boiling fractions is removed by distillation, the distillation being continued until a lubricating oil of the desired quality and of the desired flash, the and viscosity tests has been obtained.

This process of distilling lubricating oils in the presence of a decolorizing agent while agitating the mixture with aninert gas such as'steam, results in a much better decolorization and purification of the oil, and a much greater lowerin in acidity of the finished oil, than is obtainable by methods which do not involve distillation but merely heat the mixture of oil and decolorizing agent. Any

excess acid which has not been absorbed by the decolorizing agent is removed by the distillation.

The overhead distillate from the still is condensed and made use of as may be desired. The temperature of distillation depends upon the viscosit flash and fire tests of the products desire and the method of controlling these factors is well known in the art. From this still the mixture of reduced oil and clay is run through a filter press in which the oil is separated from the clay. The filter press is preferably one which will permit of a continuous treatment of the batch although it may be any other pressure type such as the Sweetland and Ke 1y presses. I preferably employ a filter which may be flushed with water and therefore will allow the entire batch to be assed through without interrupting the tering operation.

Where a filter of this type is capable of separating the clay from the oil in a single continuous operation is employed, it has been I found that as much as 750 barrels more or less of oil can be passed through the filter without the necessit for flushing out. The filter is of a type w ich is provided with means for flushing the deposits inthe filter out of the chambers by a flow ofwater. By the use of this type filter, the process is practically continuous, since the entire charge of a 1000 barrel still will amount to about 750 barrels, and experience has shown that this quantit' of oil can be passed through this type of lter without flushing out.

Filter presses in whichwater is used to flush out the deposits have not heretofore been i used for separating decolorizing agents (fullers earth, etc.) from oils, presumably because the water remaining in the filterpress after the flushim operation would be introduced into the 011.

, According tot-he process of the present in- I vention the introduction of water into the oil does not in anyway impair the final product, since all of the water may be easily removed by the vacuum treatment.

This type of filter press, which enables the deposit to be quickly and easilv removed. is thus made available by my invention.

The process of this invention described above is more economical than processes heretofore used in that the entire lubricating oil cut is refined as a whole and not in several parts. In this manner the distillation operatreatment with acid and alkali andlosses due to redistillation are diminished. Furthermore, the time consumed by these operations is shortened to a considerable extent and much less equipment and apparatus are required.

My invention is also applicable to the refining of any relatively heavy cut of lubricating oils, which it has been customary to refine after first blending them with low-boiling fractions such as naphtha, kerosene or gas oil, as described above. Instead of distilling off the low fractions before the clay treatment, as is commonly done, the mixture is distilled in the presence of a decolorizing clay. During the process of distillation, an inert gas such as steam'is used to agitate the .mixture, and the low-boiling fractions are removed and some of the lubricating oil may also be carried over. The mixture of reduced oil and clay remaining in the still is run through a filter press in which the oil is separated from the clay. As stated above, this filter press is preferably of the Merrill type,

but any other type of pressure filter, such as the Sweetland and Kelly filters, may be used.

The process of this invention is applicable to the production of lubricating oils of relatively high viscosity from any lubricating oil mixtures which contain lubricating oils of relatively high viscosity and lubricating oils of relatively low viscosity. The mixture is distilled in the presence of the decolorizing agent while it is agitated by introducing an inert gas such as steam, as described above, until the desired relatively highly viscous oil remains in the still. I

The oils leaving the filter press, produced by either of the above described methods, are then subjected to a brightening operation for the purpose of removing turbidity, which is due to the presence of moisture in the oil. All traces of moisture and any high vapor pressure fractions, which may be'mechanically or otherwise held in the oil, are removed by this operation. The brightening operation may be the blowing bright treatment which is commonly used and which is described above, or preferably the oils are treated in a partial vacuum by the method described below which is a part of the present invention.

The commonly used brightening process consists in blowing air through the oil. The disadvantages of such a process are numerous. The oil must be blown at a markedly low temperature which usually ranges from 120 to 1 80 F. v This low temperature must be maintained due to the fact that at higher temperatures in the presence of air the oil undergoes changes which impair its quality due to unknown causes, possibly 'due to oxidation. Even at these low temperatures, blowing with air, while it removes the turbidity, may impair the quality of the oil. An especially deep darkening in color is produced when the blowing bright process is applied to oils containing large amounts of moisture. Oils containing large amounts of moisture must be allowed to stand for long periods, especially if they are very viscous, in order to allow the greater part of the water to settle before they can be blown bright. A darkening in the color of lubricating oils is undesirable as dark lubricating oils are less marketable than lubricating oils of lighter I color. fLubricating oils are graded by color be treated in batches;--the process cannot be carried out continuously.

The brightening process of the present invention is an improvement on the blowing bright method in that it removes the turbidity without darkenin the oil.

Figure l is a iagrammatic view of the filter and brightening means, and

Figure 2 is a flow sheet of the invention.

The method of carrying out the bri htening operation consists in subjecting t e oil in a heated state to the action of a partial vacuum in any suitable apparatus, as, for example, in a tower. A suitable tower is illustrated diagrammatically in the accompanying drawing. From the filter press A the oil is drawn' by suction to atower 1 in which a vacuum of preferably from 27 to 28 inches is maintained by means of a vacuum pump 2. A hi her or lower vacuum may be used. The oil ows in at the top of the tower over a series of inclined shelves or plates 3 on which it is distributed as a film in order that as great a surface may be provided as ossible for the liberation of the water and ight vapors or gases. The oil collects in the bottom of the'tank and is then delivered by any suitable means, which may include a suitable pump 4, to a storage tank B.

The oil coming from the filter press may be still at a temperature of from 200 to 500 F., depending upon the previous treatment, so that in the vacuum tower the temperature is still high enough to permit of the ready separation of the water by vaporization at the reduced pressure. The temperature of the oil delivered to the tower and the vacuum conditions in the tower are such that at the reduced pressure there is no volatilization of any of the lubricating oil passing throughthe tower.

This brightening processis applicable to the treatment of any lubricating oil which contains moisture in any amount, such as finished pale or red lubricating oil stocks which have absorbed moisture on standing or otherwise. The process may, in fact, be used wherever blowing bright processes have been used heretofore. It may be used on high or low viscosity lubricating oils obtained by any refining operation. It may be applied to the brightening of a lubricatin oil which has been subjected to the usual aci and alkali treatments immediately after these treatments and without any subsequent treatment with clay, or it may be used after a clay treatment and after the clay has been removed from the oil.

The oil to be treated by the vacuum method may come from the filter, agitator or other operations at a temperature sufficient for the vacuum process and in such cases it does not need to be heated. Other oils which are to be subjected to the vacuum treatment may not be at a sufficient temperature or they may be cold, as in the case of lubricating oil stocks and in these cases the oil is preheated and then subjected to the vacuum operation.

Furthermore, the present process is more treatment of oils.

thcgas oil p containing lubricants, distillin and collecting the latter economical and effects a saving in time, especially in the case of very viscous lubricating oils and in the case of oils which contain large amounts of moisture. The present process may be carried out directly in connection with oils which contain large amounts of moisture without it being necessary to preliminarily settle out the water. Furthermore, the present process is more flexible in that it is appli cable to batch, semi-continuous or continuous The ability to treat oil continuously is obviously a very important advantage. I

The temperature of the oil undergoing vacuum treatment may vary within wide limits provided only that the temperature is high enough to cause vaporization of the moisture contained in the oil at the pressure which obtains in'the vacuum tower.

The methods of treatment above described are particularly applicable to the mixed base and asphalt base 0115. I

My process has the further advantage that it enables the production-of oils of any desired viscosity, includin lubricating oils of much higher viscosity t an have heretofore been obtained in commercial practice.

For example, I have produced from Texas crude, lubricating oil having a viscosity as high as 8000 viscosity (Saybolt universal at 100 F.) substantially acid-free, lighter than 3 color on the N. P. A. color scale, and giving a substantially perfect emulsion test.

While I have described my invention in more or less detail for the purpose of illustration of actual ractice', it is to be understood that modifications may be made without departing from the spirit thereof.

I claim 1. The process of producin lubricating oils of any desired viscosity w ich consists in distilling the lighter fractions including raction from acrudemineral oil ing the remaining portions 0 the oil as a whole until only the bottoms remain, agitatremoving the sludge, mixing the acidulate oil with a clarifying and decolorizing clay, distilling the oil to lower its acidity and remove any free acid in the resence of the clarifying and decolorizing c ay while agitating with an inert gas until a lubricating oil] of desired viscosity, flash, and fire-test ,remains in the still, continuously filtering the oil from the decolorizing clay while in heated condition, and subjecting the oil while in its heated state to the action of a partial vacuum, removing moisture by volatilization, the temperature of the oil being sufliciently high to cause vaporization of water atlthe particular pressure which is utilized. 2. The process of .move any free acid in the istillate with sulphuric acid,*

the gas oil fraction from a crude mineral oil containing lubricants, distillin and collecting the remaining portions o the oil as a whole until onl the bottoms remain, agitating the latter istillate with sulphuric acid, removing the sludge, mixing the-acidulated oil with a clarifyin distilling the oil to lower its acidity and reresence of the clarifying and decolorizing c a while agitating with an inert gas until a ubricating oil of desired viscosity, flash, and fire-test remains in the still, filtering the oil from the decolorizingclay while in heated condition,

and subjecting the oil while in its heated state to the action of a partial vacuum, removing moisture by volatilization, the temperature ofthe oil being suificiently high to cause vaporization of water at the particular pressure which is utilized.

3. The process of refining lubricating oils containing higher and lower boiling point. hydrocarbons which consists in agitating the mixture with sul huric acid, removing the sludge, mixin t e acidulated oil with a clarifying an decolorizing clay, distilling the oil to lower its acidity and remove any free acid in the presence of the clarif ing and decolorizing clay while agitating wit an inert gas until a lubricating oil of desired viscosity, flash, and fire-test remains in 'the still, continuously filtering the oil from the decolorizin cla while in heated condition, and subjecting t e oil while in its heated state to the action of a artial vacuum, removing moisture by volatilization, the temperature of the oil being sufliciently high to cause vaporization of water at the particular pressure which is utilized.

, 4; The process of refining lubricating oil containing higher and lower boiling point and decolorizing clay,

hydrocarbons which consists in agitating the mixture with sulphuric acid, removing the 1,

sludge, mixing the acidulated oil with a clari-- tying and decolorizing clay, distilling the oil to lower its acidity and remove any free acid in the presence of the clarifying and ,decolorizing clay while agitating with an inert gas until a lubricating oil of desired viscosity, flash, and fire-test remains in the still,

7 filtering the oil from the decolorizing clay while in heated condition,and subjecting the oil while in its heated state to the action of a partial vacuum, removing moisture by vola tilization, the temperature of the oil being sufliciently high to cause vaporization of water at the particular pressure which is utilized.

In testimony whereof, I afiix my signature.

- WILLIAM T. BRYANT.

roducing lubricating oils of any desired viscosity which consists in distillingthe lighter fractions including 7 isa

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