US1668313A - Manufacture of lubricating oils - Google Patents

Description

Patented May 1, 1928.

UNITED STATES PATENT OFFICE.

FRANK W. HALL, 01 PORT ARTHUR, TEXAS, ASSIGNOR, BY MESNE ASSIGNMENTS, To THE TEXAS COMPANY, OF NEW YORK, N. Y., A CORPORATION OF DELAWARE.

MANUFACTURE OF LUBRICATING OILS.

Ho Drawing.

This invention relates to the treating of hydrocarbon oils for the preparation of lubricating oils and has special reference to the manufacture of cylinder oil.

Cylinder oils are usually manufactured from residual oils resulting from the reduction of crude petroleum by distillation with the aid of fire and steam. Such residual oil is commonly termed cylinder stock or cylinder stock residuum and the term cylinder stock is used herein with that conventional meaning.

In the treatment of cylinder stocks, on account of the viscous nature of these oils as compared with less viscous lubricating oils, the ordinary methods of treating hydrocarbon oils with chemical reagents cannot be successfully employed. It has been found difficult to properly treat cylinder stocks with sulfuric acid largely because of the difficulty in settling out or removing the acid sludge products of the reaction and on account of the refractory emulsions which are formed in the ordinary neutralizing processes.

It has, therefore, been sought to refine cylinder stocks by first diluting the oil with a light petroleum distillate and then subjecting the diluted oil to the action of the acid. This method of treating, however, has been very unsatisfactory due to the fact that there is a heavy loss in acid, since the acid reacts not onlywith the hydrocarbons in the cylinder stock itself but also with the hydrocarbons of the lighter oil. An even more objectionable feature of this method of procedure resides in the character of the sludge products formed in the reaction. When the acid is applied to the mixed heavy oil and distillate the resultant sludge is of a comparatively soft character and is highly soluble in the oil mixture. The result is that the sludge does not readily settle outof the oil.

The customary neutralizing methods in use in treating other kinds of oil are practically useless in treating these heavy oils. In fact the application of the usual alkaline solutions produces emulsions of such a refrac- Application filed October 5, 1923. Serial No. 666,707.

tory nature that it is common practice not to attempt to neutralize the acid-treated oil at all and merely to settle the oil for a time and then subject it to distillation, to remove the light oil. This procedure, however, results in great deterioration of stills and vapor lines due to the presence of the acid in the oil being distilled.

I have found that cylinder stock can be satisfactorily treated and the difliculties above set forth avoided by treating the undiluted oil with acid and then adding a diluent to the oil. When the undiluted viscous oil is treated with acid a comparativel hard and tenacious sludge is formed whic is not readily soluble in a mixture of the cylinder stock and li ht oil so that whenthe light oil is added, a ter the acid treatment, the greater portion of the sludge products readily settle out.

Furthermore, I have discovered that if the cylinder stock, after treatment with acid, be subjected to the action of a concentrated orsaturated alkaline solution that the oil may be satisfactorily neutralized without the formation of the tenacious emulsions which are formed in previous methods of neutralizmg.

In order to fully disclose my invention I will now proceed to outline in detail the complete process of treatment which I have devised, the various novel features of which are set forth in the appended claims.

In practicing the invention a petroleum fraction, preferably a residue of petroleum distillation having a viscous nature suitable for cylinder oil, is subjected to treatment with a mineral acid, preferably sulfuric acid. The treatment may be carried on in an agitator or treating vessel of conventional design which it is unnecessary to describe herein. It is best to add the acid to the oil slowly in order to prevent localized burning of the oil. After the oil has been treated with the acid a diluent comprising a lighter oil, such as a hydrocarbon oil of the nature of naphtha, kerosene, or the like, is added and the oil and diluent blown with air or otherwise thoroughly mixed. The mixed oil is then allowed to stand for a time and the major portion of the acid sludge material is settled out of the oil.v

In the acid treatment a greater or less quantity of sludge material tends to adhere to the walls of the vessel and for this reason it is preferable to remove the oil after settling to another vessel. The oil is then treated with a concentrated or substantially saturated alkaline solution, preferably a ,caustic soda solution. In common practice in treating hydrocarbon oils it has been considered necessary to employ, after the acid treatment, a quantity of neutralizin material considerably in excess of the stoicIiiometric proportion required to neutralize the acid remaining in the oil and a weak or dilute alkaline solution is always employed. I have found that in neutralizing the acid remaining in the oil, after my method of treating involving the treatment of the 011 with acid and the subsequent dilution of the oil, that it is possible to effect neutralization by employing a quantity of alkaline material substantially equivalent to the theoretical amount required for neutralization. After agitating the oil with the alkaline solution the oil is allowed to settle for a time.

The oil is then agitated with pulverulent material which serves to remove the comparatively small quantity of entrained alkaline matter that may remain in the oil. In thisstep of the process I prefer to use an inert material, such as fullers earth or the like. The most economical material that I have used is fine fullers earth which has been prepared by burning and grinding spent fullers earth that had previously been used in filtering oils. After agitation with the fine clay the clay is settled out of the oil;

The treated oil is then removed to a still and distilled, preferably with fire and steam, to remove the diluent and reduce the oil to the proper test. If a filtered cylinder oil be desired the oil may, prior to the distillation, be filtered either by the percolation method or by agitating with fine clay and filtering through a filter press.

In order to more fully describe my invention a t pical instance thereof may be given:,l000 barrelsof 600 fire cylinder stock is treated with about 40 pounds per barrel of 98% sulfuric acid. The treated oil is then cut with a substantially equal volume of naphtha, the mixture blown with air and the acid sludge permitted to settle. The oil is then removed to another vessel and agitated with about 3 barrels of concentrated caustic soda solution. After settling the oil is agitated with a small quantity of fine fullers earth. After settling out the earth the oil is removed to a still and distilled with fire and steam to bring it up to 600 F. fire test. It is to be understood that the the particular type of oil employed and the particular product desired.

The process of my invention is greatly superior to other methods of treating cylinder stock. A number of comparative experiments have demonstrated that in treating oil in accordance with my invention about 15 pounds of sulfuric acid will accomplish the same results as are obtained b about 40 pounds under prior methods of operation. The cylinder oil produced is of a superior nature. For exam Ie, the carbon residue as determined by the S. T. M. carbon residue test is much lower than is the case with cylinder stock treated by prior methods. The comparatively low carbon residue may be accounted for by the fact that in my process of treatment the tarry products of the acid reaction are practicall insoluble in the viscous oil and readily sett e out when the diluent is added, whereas when the mixed heavy oil and diluent are treated with the acid, in accordance with prior methods, the sludge materials formed are of a comparatively soft nature and are so freely soluble in the mixed oil that they are not removed by any subsequent treatment.

In many cases the acid products of the reaction are so completely removed by my process in which a diluent is added after the acid treatment that it is possible to omit the treatment with the alkaline solution and at the same time avoid in the final distillation treatment the excessive deterioration of the still equipment that is characteristic of present methods of operation. Thus the cylinder stock may be treated with acid, then diluted with a lighter oil and the mixture allowed to stand for a time so that substantially all 'of the acid products of the reaction are settled out. The oil is then subjected to distillation, the acid content in the oil being so small that no material convepience or deterioration of equipment resu ts.

Obviously many modifications and variations of the invention, as hereinbefore set forth, may be made without departing from the spirit and scope thereof, and therefore, only such limitations should be imposed as are indicated in the appended claims.

What I claim is:

1. The process of manufacturing cylinder oil which comprises treating cylinder stock with sulphuric acid, adding a lighter petroleum oil to the treated oil, permitting sludge materials to settle out from the oil, and treating the oil with a neutralizin material.

2. In the manufacture of cylin er oil the process which comprises treating cylinder stock with sulfuric acid, diluting the treated oil with a lighter h drocarbon oil and treatin the mixture wit a concentrated alkaline so u'tion in quantity substantially equivalent a to the stoichiometric proportion required to neutralize the acid remaining in the oil.

3. In the manufacture of cylinder oil the process which comprises treating cylinder stock with sulfuric acid, mixing the treated oil with a lighter petroleum oil and then 10 allowing the acid sludge materials to settle out from the mixture.

In witness whereof, I have hereunto set my hand this 26th day of Sept. 1923.

FRANK W. HALL.