US1937782A - Lubricating oil - Google Patents

Description

Dec. 5, 1933. A E FEW, JR 1,937,782

LUBRICATING OIL Filed Jan. 13, 1928 3 Sheets-Sheet 1 Dec. 5, 1933. A. E. Psw, JR

LUBRICATING OIL Filed Jan. 13, 1928 H1 H1 V 3 Sheets-Sheet 2 Dec. 5,'1933. A, E FEW, JR 1,937,782

LUBRICATING OIL Filed Jan. 13, 1928 3 Sheets-Sheet 3 Patented Dec. 5, 1933 UNITED STATES vPATENT OFFICE 1,937,782 LUBRICATING OIL ration ci New Jersey Application January 13,

13 Claims.

, The object of this invention is the production, as distillates, of very high boiling point lubricating oils of fairly wide cuts having a combination of qua1ties,particularly low carbon content, good color, low organic acidity and good demulsibility, that has never heretofore characterized any distillates from petroleum.

The manufacture of low and medium boiling point lubricating oil distillates with hash and iire points characteristic of such oils and having low carbon content, good color, low organic acidity tests, good demulsibillty tests in accordance with the Herschel method, and substantially free of cracked products, presents, in the present advanced state of the art, no serious problems.

It is also possible to produce fairly high boiling point distillates having the desired qualities specified in greater or less degree.` It is also possible to produce such distillates as narrow cuts, but the production of narrow cuts on a commercial scale is not economically practicable.

Some of thc actors that are` necessary or helpful to the production of high boiling point distillates are well understood. Thus, it is well known that by the use of steam,the boiling points of the oil fractionsmay be substantially reduced, thereby substantially reducing the formation of cracked products-cracking being a factor of time and temperature; but even moderately high boiling point oils produced by distillation with steam at atmospheric pressure or a low Vacuum are objectionable because of the resultant discoloration of the oil. This discoloration `is largely the result of the production oi cracked products, 'the reductionin boiling point not being sufficient to avoid substantial cracking. t is also'in part attributable to the formation oi products ci" oxidation, which not only discolor, but unfavorably aiect other qualities of, the oil.

.So far, however, as concerns oxidation products, it is well understocd'that the introduction into the oil ci an acid neutraliser, such as caustic soda orother alkali, tends to prevent their forma- 192s. serial N0."246,446

ing point, with reduction in absolute pressure, be graphically represented by a line intersecting vertical and horizontal lines indicating respectively progressively lower absolute pressures and progressively lower boiling points, the line will be a curve something like that shown in Figs.V 4 and 5 of the drawings. This knowledge has been available to the art, and the consequent advantage of distillation under an extremely high vacuum has been known, since the publication of the work of Weilandt and Krait, Berichte, etc., vol. 29, page 1323 (1896), and vol. 38, page 263 (1904) Those skilled in the art, since the date of these publications, and possibly earlier, have been well aware of this accelerating drop in boiling point as an absolute vacuum is approached, and patentees, in describing processes of distilling oil under vacuum, have expressed the desirability of employing as high a vacuum as possible. Until Within the past eight or ten years, however, engineering diliculties have prevented the maintenance of an extremely high vacuum in the oil circulating system.

There are other factors, however, that have prevented the operativeness of very high vacuum processes in the production of very high boiling point distillates with very high iiash and fire tests and substantially devoid of cracked products. Thus, it has not been appreciated that the absolute pressure to which the oil of an oil body is subjected depends not alone, or even mainly, upon the absolute pressure in the superincumbent vapor space but depends also upon the depth of the body of oil. Thus, if the existence of a body of oil of approximately .8 sp. gr. at 500 F. and two feet in depth, under an absolute vacuum, be assumed, the hydrostatic pressure on the oil at the bottom of the column will be about 33 mm. mercury absolute. Assuming the boiling point of the oil on thersuriace of the body to be about 59D degrees F., the boiling point of the oil at the bottom of the column will be about 600 degrees F. Consequently, the boiling point of a substantial part of the oil body will be greatly above what the boiling point of the oil would be if the factor of hydrostatic pressure could be eliminated. Principally for this reason, although very high vacuum processes, as applied to batch processes, have gone into commercial use and have produced high boiling point distillates of `good quality, they have not successfully produced the very high boiling point distillates that the art demands and which it is the object of this invention to produce.

However, distilling apparatus in which the oil was widely distributed over a heated surface lil() (with resultant elimination of the factor of hydrostatic pressure) while the oil was subjected to a vacuum was disclosed as early as the date (December l0, 186'?) of the Tweddle Patent No. 72,125; but no practical use has ever been made of such an apparatus to eiect the distillation of high boiling point distillates of the desired characteristics and qualities. Indeed, it is questionable whether the process can be successfully practiced in such an apparatus; there being other factors that must coexist with an extremely high vacuum and the dispersal of the liquid oil over the heating surface, in order to successfully produce such boiling point distillates. The principal of these other factors is probably the selection of a heating agent having a high rate of heat transfer in order to maintain the smallest practicable temperature difference between the oil and the heating medium. Ordinary heating media, such as furnace gases and condensible or superheated steam, having a comparatively low rate of heat transfer, must have a temperature so far exceeding the desired boiling point of the oil to be distilled that local overheating of the oil occurs, resulting in cracking and the consequent production of a distillate having so nigh a content of products of decomposition as to render the Whole process unworkable to produce high boiling point distillates of the desired characteristics and qualities. It has been found that the use of inercr y vapor as a heating medium, provided it transfers its latent heat of condensation, meets the requirements if other necessary factors are present. Thereby a temperature difference between the oil to be distilled and the temperature of condensation of the mercury vapor may be maintained well under 50O F., thus avoiding local overheating. For mercury vapor1 it may be possible, in some cases, to substitute another vaporizable metal, or perhaps a Vaporizable metallic compound or alloy, or some other substance, such as diphenyl oxide, benzophencne, or sufur.

Still other conditions must or should coexist with those named in order to successfully produce the high boiling distillates hereinafter described.

Heat should be applied only to the liquid oil and not to the vapors. if no heat is app ied to the vapors, they tend to cool immediately a' ter leaving the surface of the oil body. lf, on the other hand, they are directly heated by the heating medium, conditions rnost favorable to cracking, if cracking is possible at the temperature to which the vapors are subjected, are produced; it having been demonstrated that oil a vapor state is more readily cracked than oil in a liquid state, s me authorities holding that the cracking or oil can proceed only when the oil is in a vapor state.

Slightly prolonged contact between the liquid oil being heated and the oil vapors should be avoided, this also being a condition productive oi cracking of the oil vapors.

The oil vapors, when condensed, produce a distillate containing iiXed gases that produce an objectionable odor. The distillate should be subn jected to a deodorizing process in order to r-move these xed gases.

The oil to be distilled must not be subjected to any preliminary processes, such as the driving oif of benzine, gasoline, kerosene, gas oil, fuel oil, or lower boiling lubricating distillates, that crack the oil, since the high boiling oils whose production is the object of the invention cannot be produced even though a substantial cracking temperature is avoided in their distillation, if the oil contains the cracked products to begin with. All such preliminary operations should be conducted, as far as possible, under non-cracking and non-oxidizing conditions. If, however, the crude oil contains cracked products, or a limited amount of cracked products are produced in preliminary operations, the use of an acid neutralizing agent, such as caustic soda, is necessary, even where all the other conditions required for successful operation are present.

Unless all, or most, of the conditions hereinbefore recited coexist in the process, the production of the oils forming the subject-matter of this invention is impossible. It is, therefore, important that the conditions required to produce them should be recapitulated, as follows:

l. The subjection of the oil, while it is being vaporized, to a very high vacuum, which should preferably be equivalent to a pressure of from one to seven millimeters mercury absolute, although this absolute pressure may be exceeded in the production of high. boiling point oils within the lower parts of the ranges of the boiling points, fiash tests and lire tests hereinafter specified.

2. The subjection of the oil to the vaporiaing operation for the shortest practicable time.

3. The avoidance of a column of oil of any substantial height, thereby making the factor of hydrostatic pressure negligible.

4l. The use of a heating agent that will make possible a small temperature difference between it and the oil, say not exceeding, and preferably substantially less than, about 50 F., so as to avoid local overheating.

5. The application of heat, principally, if not wholly, to the liquid oil, and the avoidance of conditions whereby vthe vapors, when formed, are subjected to the temperature conditions required to form then.

6. The avoidance of prolonged contact between the liquid oil being heated and the vapors that have escaped from the liquid oil body.

"l, Treatment of the crude oil in suolL manner as to insure the absence, or elimination, of cracked or oxidized products from the stock from which the very high boiling point oils are to be distilled.

8. The deodorization of the distillate.

It will be understood that all these conditions advantageously may, but need not, coexist in the production of oils having average boiling points, and flash and fire tests, below those rnbodying the present invention; and that such oils, having substantially the other desirable qualities and characteristics hereinbefore enumerated, may be process, is necessary to enable those the art to produce the new distillato. this brief description of such proc aparatus is advisable, and drawings, in which ich apparatus is set forth in detail, herewith a pended.

is a diagram, in sectional elevation, of a part of a distilling plant in which the improved distillates may be produced, showing particularly the means for heating the lubricating stock.

Fig. 2 is a diagram, in sectional elevation, of that part of the plant in' which lubricating stock `is distilled and the distillate refined.

"Fig 3 is a longitudinal section through one of the stills of Fig. 2. l

i Figs. 4 and 5 are diagrams illustrating the fall of the `boiling point with reduction in absolute pressure'.

Acomplete apparatus, including means for preparing `the lubricating stockfrom crude oil in order to` prepare a lubricating stock free of cracked or oxidized products, and for distilling on lubricating fractions, is set forth in an application filed by me January 8, 1927, Serial No. 159,754. Thepresent apparatus constitutes a part of the apparatus therein disclosed.

It may be assumedthat the oil which is tov be subjected to the treatment required to produce the high boiling distillates which form the subject of the present invention is a'high boiling residue of Texas asphalt base crude, which has been de` prived of all its (relatively) lower boiling constituents, including all` the low boiling and medium boiling lubricating fractions and, indeed, including also what the art recognizes as high boiling lubricating fractions. What is-left is com- .posed,`either wholly or `in large part, of a residue 3o that has never before been distilled without such substantial cracking as to make the distillate un fit for use as a lubricating oil unless reduced with steam and fire, and subsequently treated, at

a comparatively high cost, and which resultant m lubricating oil is inferior in fire andflash tests and lacks also the combination ofother qualities Vwhichit is the object of `this invention to pro` duce. -It should,`also, be understood that these oil fractions from which inferior distillates have been heretofore produced at highcost comprise the most valuable lubricating constituents of the crude, and which, when isolated as a distillate, command prices much higher than that of any other heretofore known lubricating oil distillate. From a mercury boiler a extends a mercury vapor line b having branches extending to the mercury chambers d of two vaporizers 9 and 10. In the production ofnew oils,'the use of two vaporizers, in which successively higher boiling point fractions are evaporated, is advisable, in

that a satisfactory commercial product can be made `from a mixture of the two distillates. Each branch pipe is equipped with avalve c, by means of which the ow of mercuryvapor into the mercury vapor chamber d of either vaporizer, 9 or l0, may be independently regulated. Extending from the mercury chamber d of each vaporizer isla mercury condensate return e;

communicatingwith a pressure control valve g, which opens when the boiler pressure exceeds a predetermined maximum and allows mercury vapor to flow past the valve into a condenser h,

i which communicates, through a pipe h', with the boiler a either director through the mercury asphalt, which may be sold as such, or further From the 1 mercury vapor supply line b extends a pipe f into vaporizer 9 and if the temperatures are properly regulated, `the fraction vaporized in vaporizer 10 is of so high a boiling point that the residue constitutes practically nothing but refined to improve its quality. There need be no. waste intermediate product.

For the two vaporizers may be substituted, as above stated, a single long vaporizer, and if two or more distillates of progressively higher boiling points are desired, progressively higher boiling point vapors may be taken off at different points along the length of the vaporizer, and fractionally condensed. It is preferred to use two vaporizers in `order to provide a minimum effective temperature difference between the oil `in each vaporizer and the mercury vapor in each vaporizer. It is also permissible to use more than two vaporizers. In any case, however, it is desirable tQpIOvide a number of vapor exit pipes k along i the length of each vaporizer so as to allow the vapors to freely and quickly escape as soon as they leave the surface of the liquid oil body.

Connected with the oil vaporizing chamber of each vaporizer is a condensing, refluxing and deodorizing apparatus, which will now be described.

The vapor from pipes 7c flows into a header m and thence throughpipe 1L to the lower part of a tower o. Above the discharge mouth of pipe n is a grid p, which supports chemical tiles, such 195 as Raschig rings, r. Above and spaced from tiles 1" is another grid s, which supports another pile of tiles t.

Below grid s and above tiles r is provided a deector u and an oriced pan u through which 119. oil vapors can flow upwardly and which `is adapted to receive reflux condensate, which is carried off through pipe 20;

The bottom of the tower communicates, through pipe 1u, with the oil feed end of one 115 of the vaporizers, 9 or 10, preferably the same vaporizer as that from which the oil vapors pass into the bottom of the tower.

The top of the tower communicates, through a pipe rc, with a stink oil receiver y, to which is connected a pipe e connected with vacuum.

. Any vapors carried into tower o that are heavier than the fraction which it is desired to segregate will condense while going through tiles rand flow down to the bottom of the tower. Any particles `of oil that may be entrained with the vapors will also flow to the bottom of the tower.

, The uncondensed vapors will flow up through plan v, grid s and tiles t, wherein the vapors are cooled and most of them condensed. Uncondensible gases escape through pipe o: into receiver y.' The condensateflows back through tiles t and grid s into receiver o, whence it flows through pipe 20 into a deodorizer 21.

Deodorizer 2l comprises a chamber provided withstaggered flow plates 22 over which the distillate is thinly distributed and down which it flows at a speed sufficient to create a substantial turbulence. Outlet pipes 23 connect with a header 24, which connects with vacuum. The bottom of chamber 2l connects, through a pipe 26, with a receiver 27, which connects, through a pipe 28, with vacuum.

In `the deodoriaer, odoriferous gases are removed from the oil on each plate 22 and are withdrawn through pipes 23; the arrangement being such that there can be no reabsorption of gases in the oil.

The oil passing into receiver 27 is ready for the n market without further treatment. luc

.operation of the The vapors leaving the vaporizer 9 or 10 are thus subjected to partial reuxcondensation and to dcodorization, by removal of odor producing gases, rst, in the tower o and iinally in the deodorizer 21.

The nal residue from the oil vaporizer chamber y' of vaporizer l0 flows into a tank 39, which maybe connected to Vacuum through pipe 3l.

The highest degree of vacuum, which may be equal to an absolute pressure of (say) one to live millimeters mercury, is that operative on the deodorizer 2l, and receivers 30, y and 27, particularly on the deodoriser. Without obiectionably large connecting pipes, there is some drop in vacuum between the vacuum pumps and the oil vaporizing chambers of the Vaporizers, particularly if a reiiuxing and condensing tower is used. It is quite possible, however, to maintain a pressure in the oil Vaporizers of from two to ten millimeters mercury absolute. If a very wide range of cut is desired, the tower o may be eliminated and a fractional condenser substituted and the heavier condensate passed to the deodorizer, thence to storage. It is possible to maintain, in the vaperizers, if desired, a degree of vacuum more nearly egual to that at the vacuum pumps than where a tower o -is employed.

The importance ci maintaining in the vaporizers a degree of vacuum as near as possible to an .absolute vacuum may be appreciated by reference in boiling points in the very low pressure range.

Fig. fr shows more clearly the accelerated rate at which the boiling point falls as an absolute vacuum is approached. l

Fromlthis diagram it will be clear that in 'the described apparatus, if it is desired to produce the very highest boiling distillates, a reduction in absolute pressure to substantially below ten mm. mercury is quite necessary, and a reduction, if possible, to, or even below, one or two inm. mercury is desirable.

In producing distillates embodying this invention, it is essential that the lubricating; stock fed to vaporizer 9 should be stock that has been divested of its lower and medium boiling lubricatingv fractions` Preferably, such lubricating fractions are removed by passage through a series of vaporizers (whichv may be, for example, eight in number) like vaporizers 9 and l0, wherein, however, the establishment of a very high vacuum is not essential, because, even in the last vaporizer of the series preceding vaporizers 9 and l0, the temperature to which the oil is raised does not exceed the temperature at which, with the absolute pressure maintained therein, substantial. cracking begins. It should also be understood that l do not necessarily contemplate the production of the new oil in vaporizer 9. The new oil is preferably the product of vaporizer 10, or is a blend of the products of vaporizers 9 and l0. g

As an example of one way of producing the new oils, let it be assumed that an asphalt base oil, such as Texas crude, has been subjected to a succession of distillation processes under such conditions as prevent the substantial production of cracked products, and that the oil has beendeprived of all its lighter constituents and of the" major part of its lubricating fractions, leaving a residue containing, in addition to asphalt, only the higher boiling fractions which it is desired to separate as distillates. Thus, it may be assumed that, before the introduction of residual oil to vaporizer 9, the distillation process has involved the subjection of the oil, in the immediately preceding vaporizer, to a temperature of G-650 F. at some pressure between atmospheric and one inch mercury absolute, that all or most of the fractions that distil off at that temperature and pressure have been distilled ofi, and that the residual oil is free of coke and other cracked residues. Or it may be assumedthat the residual oil contains high boiling fractions which, if isolated as a composite distillate, will have, as an example, a gravity of 17.8, a flash point of 510- 515 a re point of 595-600o F., and a viscosity oi 149/2102 In other words, all that it is necessary to assume is that the residual oil entering vapcrizer 9 contains high boiling fractions all or a large part of which are those which it is the object of 'this invention to separate out as distillates.

Such a residual oil is now run through Vaporizers 9 and l0, under the conditions prescribed: namely, the use of a heatinfr agent which, like ercury vapor, is capable of transferring its latent heat ci condensation at a temperature not greatly exceeding the boiling point, at a very high vacuum, of the highest boiling fraction that is to be vaporized; the maintenance on the oil being vaporized of a very high vacuum equivalent to an absolute pressure of (say) two to ten millimeters hmercury, and preferably as low as possible, especially in vaporizer l0; the avoidance of hydrostatic pressure; the subjection of the oil to the heatin'T agent for only the limited time required for the oil to traverse the length of the pan; the direct transfer ci heat (through the pan) only to the liquid oil; and the free escape of the Vapor; all as hereinbefore described.

The distillate obtained from vaporizer 9 may or may not be an oil embodying this invention; that is, it or may not have all the characteristics, hereinafter described, of the new oil. Thus, it may have a ilash point of 470 F. or somewhat less, a iire point of 550 F. or somewhat less, and a viscosity of 120 at 210 E.; or the flash and fire points and viscosity may be much higher. yThe distillate obtained from vaporizer 10, however, does have all these characteristics in such maximum degree that, when blended with the distillate from vapori/cer 9 in (say) about equal proportions, it produces an oil which has such novel characteristics in a less pronounced degree and which is more readily marketable than the distillate from vaporizer l0.

Bearing in mind that the oil in vaporizer l0 is distilled so as to leave a residue comprised mainly or wholly of asphalt, the following are examples of different distillates obtained from vaporizer 10.

It shouldbe stated that the viscosity characteristics of the distillate are subject to wide variation and depend primarily on the kind' of crude which is run through the plant.

ist

It should also be understood that suchcharacteristics as the-gravity, and the flash and fire points, of a distillate from the final vaporizer depend on the proportion of the highest boiling any distillates heretofore produced from mineral oil. They are, indeed, so much higher than is required for any ordinary purposes that they can advantageously be blended with a lower boiling fractions that have beenabstracted from the oil distillate, such as, for example, the distillate before it enters the final vaporizer. Thus, by from vaporizer 9. The following' is a distillaincreasing the number of vaporizers, so as to detion analysis of a blend of the latter distillate crease the amount of the highest boiling oil that with the three distillates I, II and III from is vaporized in the last vaporizer, the distillate .vaporizer 10: therefrom may be made to have ash and fire Gravity 17.0 flash 510; fire 600; viscosity 85 tests even higher than those characterizing dis- 149/210. tillate IV; and the same result may be accom- Charge 1200 cc. No soda. plished by careful fractional condensation of the Initial l---566 at 2 mm.

Temp. out Pres. Amm. chg. ggg? riash rire viscosity cfr. ,ggg

Vap. `Liq.`

520 55s 2mm.` 12o ce. 470 540 115/210 33/1 95 535 570 2mm. 120 0c. 485 550 12s/210 3% 54s 582 2mm. 120 ce. 400 570 120/210 4+ 550 58a `2 mm. 120 ce. 500 575 137/210 ai 551 59s 2mm. 120 ce. 510 595 13s/210 41,5 572` 015 2mm. 120 0e. 525 010` 141/210 414+ 584 020 2mm. 120 ce. 550 530 155/210 (+2) 454 500 550 2mm. 120 00. 560 040 159/210 (+0) 51,5 100 044 vso 2mm. 12o ce. 575 6:10 152/210 (+20) su distillate from thelast one or more vaporizers. It will be noted that even the blended dis- On the other hand, the production of distillates tillate has very high flash and re tests with exhaving the extremely high flash and re tests of cellent color; and that the first 10% fraction has 105 distillate IV is not ordinarily required. a flash point not lower than 470 F. and a nre The following is a distillation analysis of dispoint not lower than 540 F. and that the ninth tillate II. Cuts were made equaling ten per cent. 10% fraction has a flash point not lower than fractions. The vapor temperature is recorded 575 F. and a fire point not lower than 640 F. in the first column and the liquid temperature It will also be noted that even the blended disin the second "column these temperatures tillate has nre and flash points so high that the being those at the ends of the distillation of proportion of the lower boiling blended distillate the respective fractions. The oil started to distil may be increased and yet produce an oil having at a liquid temperature of 600 F. and at a vapor characteristics heretofore unknown in mineral temperature of 500 F. under two millimeters lubricating oil distillates. 115

f mercury absolute pressure.` The last ten per cent. fraction could not be distilled Gravity 17.7; flash 540; fire 640; viscosity 196/210.

Charge 1200 cc. Initial 500-600 at 2 mm.

The characteristic features of the improved oil may be enumerated as follows: An oil having a flash point within the range 480 575 F. and preferably over 500 F., a fire point Within the range 560-660 F. and preferably over 580 F. 120 and being further characterized by the fact that Temp. 1 Cut Pres. Am't. Chg. (giggle Flash Fire Viscosity C.T. 125

v Vap. Liq.

58s 052 2mm 120 ce. 450 540 143/210 534 59e 542 2mm 120 00. 510 500 162/210 s 500 04s 2mm 120 ce. 530 515 l1511/210 6 610 055 2mm 120 cc. i 5% 130 614 672 2mm 120 cc. 5% 51s 57e 2mm 120 00. 0 622 672 1mm l20 cc. 6% G35 08s 2mm 120 ce. 51.5 555 71s 2mm 120 ce. 624 v oc. `1,200cc.

It will be noted that all the distilled oils I, II, its Conradson carbon content does not exceed III and IV have a flash point not less than 535 seven-tenths of one per cent. (.007), that its F. and a fire point not less than 625 F. Distillate color is not more than 71/2 N. P. A., that the oil IV merely illustrates how much higher it isV posis neutral, that is, its organic acidity as tested sible, in my process, to carry the flash and fire by the A. T. M. methodv does not exceed twopoints. Distillation analyses of distillates I, II hundredths and that it has a good demulsibility and III show that the first ten per cent. is charactest in accordance with the Herschel method, terized by having a flash point not lower than e., between 1550 and 1620. `480 F; and a fire point not lower than 540 F. The Conradson carbon content will vary with 145 and that the ninth 10% fraction has a flash the crude. Oils of the ash and fire points herepoint not lower than 580 F. and a re point not in described, produced as herein described, vary lower than 680 F. in their Conradson carbon content, from .4 to

The flash and fire points of these oils are, it is less than one percent. In the case of the parbeleved, far higher than those characterizi,11i-2. tlllal' GrlldGS. herein mentioned the Conradson 150 carbon content of the oils produced as herein described is between .5 and .7 percent.

It is known to produce distillates of low flash, fire and viscosity having a Cornadson carbon content substantially less than one percent. It is also known to produce distillates having low flash, fire and viscosity that have low organic acidity. It is also known to produce residual (cylinderoils having a high lash and fire (but lower, it is believed, than the minimum characterizing the oils herein described), which are neutral. t is, however, believe, unknown to produce distillates of the high flash, lire and (or) viscosity characterizing the oils herein described, or to produce distillates of high flash, fire and (or) viscosity which are neutral, or to produce distillates or residual oils of high flash, re and (or) viscosity which have a Conradson carbon content under one percent, and it is certainly unknown to produce distillates having all of the qualities specified.

It will be observed that certain of the characteristic features of the new oil are those possessed by high grade bright stock, which is a final, highly refined and expensive residue from paraflin base oils; but bright stock is a residual oil and lacks important and valuable characteristics of the new distillates. Thus it is impossible to reduce the carbon content of a residual oil much below one per cent. (Conradson test); nor is it possible, with a residual oil, to obtain a color comparable to that hereinbefore specified for the new distillate, except by filtration at an excessive cost. It is one of the pronounced advantages of the improved distillate that it possesses the required and desirable qualities of the best and much more expensive cylinder oil or bright stock and at the saine time possesses other superiorities. Thus, a low carbon content is in itself a desideratum, while the good color is indicative of the comparative absence of undesirable products of decomposition.

For certain restricted uses the distillate from vaporizer 10 should not be blended, or should be blended with but a small proportion of oil from vaporizer 9; and an oil having a flash point of not less than 525 F. and a nre point of not less than 605 F., and with the other qualities specified, is a specinc example of a very high boiling point oil that is within the broader scope of the invention.

No specific viscosity range characterizes the new distillates, inasmuch as various kinds of crudes will produce oils all having the essential qualities hereinbefore enumerated but varying greatly in viscosity. The flash and fire tests of lubricating oils of similar viscosity from different crudes will vary within rather wide limits. Thus, Vinton crude yields a fraction having a viscosity of 200 210 F. with a flash point of 515 F. and nre point of 610 F. Mirando crude yields a fraction of the same viscosity having a flash point of only 470 F. and a re point of only 510 F. The average boiling point of the fraction of Vinton crude oil at 2 mm. absolute pressure is approximately 610 F., while the average boiling point of the fraction of Mirando crude oil at the same pressure is approximately 510 F.

Now it is well understood that a distillate having high fire and ilash tests with a relatively low viscosity is much more desirable valuable than a distillate having the saine fire and hash tests with a relatively high viscosity. 1t is a characteristic feature of the process herein described that, with a given crude oil, a distillate can be obtained that, for a given viscosity, has much higher ilash and re points than any heretofore known; but the viscosity characteristic cannot be expressed in the claims, because it necessarily varies within a wide range dependent on the crude.

Another pronounced advantage of the process by which the new distillates are produced is that it is possible to produce low viscosity and high dash and fire test distillates from crudes that heretofore could not be commercially used to produce high boiling distillates because of the too high viscosity by which they were inevitably characterized.

It should be stated that it may be possible to produce, from certain crudes, by processes heretofore known, lubricating distillates having nre and flash tests approximating the lower limit of the ranges heretofore specied as characterizing the new distillates; but such distillates, aside from hash and fire tests, are either cuts too narrow to be commercially practicable or do not have the combination of characteristics and qualities herein specified as characterizing the new distillates.

In different claims among those appended, the minimum ash and fire points are differently 10() stated: first, because while the lower limits of the flash and fire ranges specified distinguish from all distillates known to me, they may not of themselves distinguish from distillates unknown to me; and second, one of the main objects or advantages of the invention is the production of a distillate that will possess the desirable qualities of known residual oils such as the best bright stocks; and such distillates, to meet the exacting requirements of many uses, must possess fiash and hre points rauch higher than those within the lower part of the broadest range specified, and clairnrJ limited to distillates that are competitive with, and at the same time superior to, such residual oils are necessary in order to define the more radically novel, as well as the most cornmercially valuable, embodiments of this invention.

1t should be understood that if a narrow cut of the new distillate is desired, this presents no difliculties, since in the process described, as many fractions as desired may be obtained by increasing the numberof vaporizers, or by separately condensing the vapors escaping from diiferent points along the length. of a vaporizer, or by fractional condensation of the vapors. The higher boiling of such narrow cuts have extraordinarily high ilash and nre points, but their production is not usually commercially practicable, because their abstraction necessarily reduces the flash and fire points of a blend of the remaining fractions.

Having now fully described my invention, what I claim and desire to protect by Letters Patent is:

1. A lubricating oil which is a distillate of petroleum and which has a flash point about the range 550 to 675 and a higher fire point 135 within about the range 625 to 730 F. and which is further characterized by the fact that its organic acidity as tested by the A. S. T. method does not exceed two-hundredths neutralization number and that its Conradson carbon content is between four-tenths percent and one percer 2. A lubricating oil which is a distillate of petroleum and which has a flash point within about the range 575 to 675 and a higher fire 145 point within about the range 650 to 730 F. and which is further characterized by the fact that its organic acidity as tested by the A. S. T. M. method does not exceed two-hundredths neutralization number and that its Conradson carbon content is between four-tenths percent and one percent.

3. A lubricating oil which is a distillate of petroleum and whosecomponents are such that when fractionally distilled its iirst ten per cent. fraction `has a flash point within about the range 460 to 550 F. `and a :tire point within about the range 530 to 650 and that its ninth ten per cent. fraction has a higher ilash point within about the range 560 to 675 F. and a higher iire point within about the range 625 to '730 F. and which is further characterized by the fact that its organic acidity as tested by the A. S. T. M. method does not exceed two-hundredths neutralization number and that its Conradson carbon content is between four-tenths percent and one percent.

4. A lubricating oil which is a distillate of petroleum and which has a flash point within about the range 500 to 640 F. and a higher iire point within about the range 590 to 710 F. and which is further characterized by the fact that the boiling point range `between the initial boiling point and the boiling point at the end of the ninth ten per cent. fraction is not less than about F., that its organic acidity as tested by the A. S. T. M. method `does not exceed twohundredths neutralization number and that itsV Conradson carbon content is between four-tenths percent and one percent.

5. A lubricating oil which is a distillate or petroleum and which has a ash point within about the range 500 to 600 F. and a higher re point Within about the range 590 to 700 F. and which` is further characterized by the fact that the boiling point range between the initial boiling point and the boiling point at the end of the ninth ten percent fraction is not less than about 100 F., that its organic acidity as tested by the A. S. T. M. method does not exceed two-hundredths neutralization number and that its VConradson carboncontent is between` fourtenths percent and one percent.

6. A lubricating oil which `isa distillate of petroleum and which a hash point within about the range 500 te 640 F. and a higher fire point within about the range 590 lto 710 F. and which is further characterized by the fact that the boiling point range between the initial boiling point and the boilinrr point at the end of the ninth ten per cent. fraction is not less than about 60 F., thatits Conradson carbon content isY be` tween four-tenths percent and one percent and that its organic acidity es tested by the A. S. T. M. method does not exceed twohundredths neutralization number. l

7. A lubricating oil which is a distillate of petroleum and which `has a flash point within.

about the range 510 to 640 F. and a higher re point within about the range 595 to 710 F. and which is further characterized by the fact that the boiling point range betwen the initial boiling point and the boiling point at the end of the ninth ten percent fraction is not less` than about 60 F., `that its organic acidity as tested by the A. S. T. M. method does not exceed Vtwo-hundredths neutralization number and that which is further, characterized by the iactthat .l

the boiling point range between the initial boiling point and the boiling point at the end of the ninth ten percent fraction is not less than about 100 F., that its organic acidity as tested by the A. S. T. M. method does not exceed twohundredths neutralization number and that its Conradson carbon content is between four-tenths percent and one percent.

9. A lubricating oil which is a distillate of petroleum and which has a flash point within about the range 510 to 600 F. and a higher re point within about the range 595 to '700 F. and which is further characterized by the fact that the boiling point range between the initial boil--Y ing point and the boiling at the end of the ninth ten per cent. fraction is not less thanY about 100 F., that its Conradson carbon content is between four-tenths percent and one percent and that its organic acidity as tested by the A. S. T. M. method does not exceed two-hundredths, neutralization number.

l0. A lubricating oil which is a distillate of petroleum and which has a ilash point within about the range 525 to 640 F. and a higher fire point within about the range 610 to 710 F. and which is further characterized by the fact that the boiling range between the initial boiling point and the boiling point at the end of the ninth ten per cent. fraction is not less than about 60 F., that its organic acidity as tested by the A. S. T. M. method does not exceed two-hundredths neutralization number and that its Conradson carbon content is between four-tenths percent and one percent.

11. A lubricating oil which is a distillate of petroleum and which has a flash point within about the range 525 to 600 F. and a higher nre Vpoint within about the range 610 to 700 F. and

which is further characterized by the fact that the boiling range between the initial boiling point and the boiling point at the end of the ninth ten per cent. fraction is not less than about 100 F., that its organic acidity as tested by the A. S. T. M. method does not exceed twoehundredths neutralization number and that its Conradson carbon content is between four-tenths percent and one percent. Y l

12. A lubricating oil which is a distillate of petroleum and which has a flash point within the range 550 to 640 F. and a higher nre point within about the range 6.25 to 710 F. and which is further characterized by the :tact that the boiling range betwen the initial boiling point and the boiling point at the end of `the ninth ten per cent. .A

fraction is not less than about 60 F., that its organic acidity as tested by the A. S. T. M. method does not exceed two-hundredths neutralization number and that its Conradson carbon content is between fourth-tenthe percent and one percent.v

13; A lubricating oil which is a distillate of petroleum and which has a ash point within the range 575 to 640 F. and a higher fire point Within about the range 650 tc ill" F. and which a fis further characterized by the that the boiling range between the initial boiling point and the boiling point at the end ci' the ninth ten per cent. fraction not less than about 60 F., that its organic acidity as tested by the A. S. T. M. method does not exceed two-hundredths neu tralization number and that its Conradson carbon content is between four-tenths percent and one percent.

ARTHUR E. PEW, JR.

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