US3285848A

US3285848A - Preparing dissimilar oils by hydrocracking

Info

Publication number: US3285848A
Application number: US306247A
Authority: US
Inventors: Robert E Donaldson; Robert F Mansfield; Rice Theodore
Original assignee: Gulf Research and Development Co
Current assignee: Gulf Research and Development Co
Priority date: 1963-09-03
Filing date: 1963-09-03
Publication date: 1966-11-15
Anticipated expiration: 1983-11-15
Also published as: DE1271869B; DK113161B; GB1024006A; NL6410274A

Description

Nov. 15, 1966 R. E. DONALDSON ET AL PREPARING DISSIMILAR OILS BY HYDROGRACKING Filed Sept. 5, 1963 b 1, mg \I N 2 Q E a m 0 N Q N g \F a Q L! Q u r "4 Y Q Q; R w E Q Q g N z Q Q m 1 T N 0 INVENTORS.

ROBERT E. DONAL DSON ATTORNEY.

United States Patent 3,285,848 PREPARENG DISSlMILAR oILs BY HYDROCRACKING Robert E. Donaldson, Penn Hills Township, Allegheny This invention relates to the hydrogen treatment of hydrocarbons which include hydrocarbons boiling in the lubricating oil range in order to simultaneously produce high quality lower boiling fractions and high quality lubricating oils.

It is known that lubricating oils of high quality can be prepared by relatively severe hydrogen treatment of lubricating oil stocks. (See for instance Beuther et al. 2,960,- 458, November 15, 19 60, and 3,078,238, February 19, 1963.) These procedures are however primarily directed to the production of lubricating oils and little or no consideration is given to the production of lower boiling products such as jet fuel, furnace oil or the like. It is also known to hydrocrack hydrocarbons in order to obtain jet fuels and naphtha or gasoline. (See for instance Folkins 2,956,002, October 11, 1960.) However, in such procedures, little or no consideration is given to the production of lubricating oils. It is also known to treat lube oil stocks in the presence of a hydrogenation catalyst deposited upon a non-cracking base and recycle unreacted lube oil stock. (See Watkins et al. 2,787,582, April 2, 1957.) However, in this patent hydrocracking and recycling of light lube oil portions of the product are avoided.

This invention has for its object to provide a process whereby high quality gasoline and/ or middle oils as well as lubricating oils can be produced simultaneously by recycle hydrocracking of a hydrocarbon mixture which includes hydrocarbons boiling in the lubricating oil range. A further object is to provide a flexible recycle hydrocracking process whereby petroleum fractions can be simultaneously converted into high quality middle oils and lubricating oils in a variety of proportions. Another object is to provide a hydrogen treatment process in which a high furnace oil-to-naphtha ratio is obtained simultaneously with a distillate lube oil of high viscosity index. Other objects will appear hereinafter.

These and other objects of our invention are accomplished by subjecting a distillate hydrocarbon fraction which boils above furnace oil, i.e., above about 650 F., and which includes hydrocarbons boiling in the lubricating oil range or a mixture of such a distillate with a deasphalted residuum to a hydrocracking treatment in the presence of a two-component catalyst comprising essentially a hydrogenating component composited with a support possessing active cracking properties under hydrocracking conditions of temperature and pressure. The product thus produced is subjected to distillation to separate furnace oil and lighter fractions and a higher boiling fraction which includes lubricating oil components. A part of this higher boiling fraction is subjected to a treatment for preparation of a finished lubricating oil. A portion of this higher boiling fraction which includes distillate lubricating oil components is recycled to the hydrogen treatment. We have discovered that by operating in this manner two different types of hydrogen treatments may be simultaneously carried out in the same reactor. In addition these 3,285,848 Patented Nov. 15, 1966 two reactions simultaneously carried out in this manner can be made to cooperatively form practically any desired proportion of lubricating oil, furnace oil or lighter products such as naphtha. This is of real economic importance not only as regards flexibility in meeting varying market demands for these products but also enables a refiner to produce furnace oils and lower boiling products in its lube oil hydrogen treating unit or vice versa. Thus one unit is made to serve the purpose of two units.

The feed stock may be any distillate which boils above about the furnace oil range (i.e., above about 650 F.) which contains components boiling in the lube oil range, or it may be a mixture of any such distillate with a deasphalted residuum. It is advantageous to employ a feed which has a relatively wide boiling range. An example of a satisfactory distillate of this wide boiling type would be a high boiling gas oil having a boiling range in the range between about 650 and 10 50 F, or a vacuum gas oil. Another example of a satisfactory feed is a mixture of catalytic cycle stock and any lube oil base stock or any fraction which contains such a lube oil base stock. Residual feed stocks are usually employed as additions to the feed stock when it is desired to obtain lube oil products having a high viscosity such as the heavier automotive lube oils and/or cylinder stock. In the event that a feed containing residual stocks is used the residuum should be relatively free of asphaltic materials. Any known deasphalting procedure can be used for preparing the residual feed stock. Our invention is not limited to the use of any particular proportions of distillate lube oil or residual lube oil components in the feed stock. These proportions will depend entirely upon the relative proportions of furnace oil and/ or lighter products which are desired as compared with the amount of lube oil products desired. If larger amounts of high viscosity lube oils are desired, larger amounts of deasphalted residuum should be present in the feed. If larger amounts of distillate lube oils are desired, the feed will ordinarily contain larger amounts of distillate lube oil components, and may be composed entirely of components boiling in the distillate lube oil range. If smaller amounts of lube oils of all types are desired, the feed will contain relatively small amounts of lube oil components, particularly higher boiling components. It will be evident that the recycled portions of the product, which will always include lube oil components, must be taken into consideration in determining the amount of lube components to be present in the fresh feed.

The recycle rate is maintained in the range between about 15 percent and 250 percent and is preferable in the range of 33 to 230 percent based on the gas oil portion of the fresh feed. The recycle is obtained by subjecting the product from the hydrogen treatment to distillation to separate one or more distillate lube oil base fractions. A portion of any one or more of these fractions is recycled. The recycled gas oil contains components which correspond in boiling range to that of the desired distillate lube oil products. The remainder, i.e., the unrecycled portion boiling in the lube oil range, is subjected to conventional procedures, such as dewaxing, etc. for preparation of finished lubricating oils. Of course the furnace oil and lighter portions of the product are subjected to distillation to separate the desired products such as furnace oil, jet and diesel fuel, naphtha, etc.

The catalyst employed in our process is a two-component catalyst comprising a hydrogenating component and a support having substantial cracking activity. These hydrogenating components may be in the form of a metal,

0.) the sulfide or the oxide or mixtures thereof. A mixed Group VIa metal sulfide with an iron group metal sulfide such as a mixture of nickel and tungsten sulfides or chemical combinations such as nickel thiotungstate are especially advantageous. However, other satisfactory hydrogenating components include nickel, cobalt, platinum, palladium, oxides thereof and/or sulfides thereof. The catalyst may contain a halogen such as fluorine. The active cracking carrier or support for the hydrogenating component may be any carrier having substantial cracking activity such as a conventional silica-alumina cracking catalyst whether prepared synthetically or by acid treatment of various clays. A particularly advantageous support is a silica-magnesia cracking catalyst since it has been found that such a support increases the yield of furnace oil and lubricating oil yields with relatively minor amounts of naphtha or gasoline being formed. Also an alumina the fresh feed and the amount of distillate lube oil recycle,

In the accompanying drawing we have illustrated diagrammatically equipment in which one embodiment of our invention may be carried out. This specific embodiderived from the hydrous alumina described in US. application Serial No. 189,985, filed April 25, 1962, may be used. In general any carrier having a cracking activity of above 25 and preferably above 35 on the Kellogg cracking activity scale may be used. Further details on satisfactory catalysts and supports will be found in the above mentioned Beuther et a1. patents.

The hydrocracking process is carried out utilizing a hydrogenpartial pressure between about 1500 and 3500 p.s.i. and preferably between about 2000 and 2500 psi. Although higher hydrogen partial pressures than 3500 p.s.i. may be employed, usually there is no advantage in using them. The temperature may be from about 650 to about 350 F. and is preferably from about 700 to about 825 F. The fresh catalyst or a freshly regenerated catalyst has relatively high activity and it is therefore desirable to employ a temperature in the lower portion of the above mentioned ranges during the initial stages of the reaction and to increase the temperature during the processing cycle in order to maintain the reaction more or less at a constant rate. The space velocity may vary from about 0.2 to 10 volumes of charge per volume of catalyst per hour and preferably is maintained between about 0.5 and 3.0. The hydrogen rate should be above about 500 s.c.f./bbl. and is preferably between about 4000 and 20,000 s.c.f./bbl.

The severity of the reaction is controlled by selection of appropriate temperatures and/or space velocities. Of course the temperature and space velocity are maintained within the limits indicated above. The amount and type of product produced can be controlled by controlling the severity of the reaction conditions. The severity is increased by increasing the temperature or employing a lower space velocity. The amount and type of product produced can also be varied by varying the amount of recycle. The amount and type of product can also be controlled by the type of catalyst carrier employed. Thus a silica-alumina carrier of high cracking activity will decrease the furnace oil-to-naphtha ratio while a silica-magnesia carrier will increase the furnace oil-to-naphtha ratio. Thus by selection of temperature and space velocity, by variations in the components of the feed and by using an appropriate catalyst carrier it is feasible to obtain the desired product 'or products in practically any desired ratio. For instance, if naphtha is to be maximized and furnace oil reduced, a more severe type of operation would be employed and probably a lower boiling type of feed stock would be used. Also a silica-alumina catalyst carrier could be employed to increase the yield of naphtha versus furnace oil. On the other hand, if furnace oil is to be maximized, a less severe type of operation as regards temperature and/or space velocity would be employed. Also a somewhat higher boiling point feed stock and/or a silica-magnesia catalyst carrier would be used. Lube oils can also be simultaneously maximized or reduced by the same expedients and particularly by arying the amount of heavy or light lube components in ment is the treatment of a mixture of a gas oil and a deasphalted residuum. Referring to the drawing, this feed stock together with distillate lubricating oil recycle and hydrogen are fed via lines 1, 2 and 3 respectively to heater 4- where they are brought to reaction temperature and transferred via line 5 to combination hydrotreaterhydrocracker 6. Hydrogenated efiluent is fed via line 7 to high pressure separator 8 from which hydrogen recycle gas is withdrawn through line 9, scrubbed, if desired, in a scrubbing unit (not shown) and mixed with make-up hydrogen fed through line 10. Efiluent from separator 8 is fed through line 11 to low pressure separator 12 whence wet gas is withdrawn through line 13 and flared or otherwise disposed of. Efiluent from the separator 12 is fed via line 14 to atmospheric fractionator 15. Naphtha and lighter fractions are taken off overhead from fractionator 15, through line 16 for further fractionation. A side stream 17 from fractionator 15 is a furnace oil product. The bottoms from fractionator 15 are fed via line 18 to a vacuum fractionator 19 where a very heavy gas oil or a light lubricating oil fraction is taken overhead through line 20. This overhead from tower 19 is withdrawn through line 20 and in part recycled via line 2 and in part fed through line 21 to dewaxing unt 22, from which a light lubricating oil blending stock of very high viscosity index is withdrawn via line 23.

The bottoms from tower 19 comprising heavy lubricating oil stock is fed via line 24 to dewaxing unit 25. Dewaxed heavy oils withdrawn through line 26 may be further fractionated to provide blending stocks of moderately high viscosity index and high viscosity. Alternatively, the heavy lubricating oil stock withdrawn from tower 19 via line 24 may be further fractionated prior to dewaxing. Any portions of the heavy lube oil stock not required for lube oil products can be recycled to produce additional amounts of lube oils and/or furnace oil, as described above.

It is obvious that the light stock (after removing the recycle) and the heavy lube stock withdrawn from tower 19 could be combined and dewaxed in a single unit. The combined dewaxed stream could then be further fractionated to produce several lube oil blending stocks of the desired viscosities. Regardless of the dewaxing scheme employed, the wax produced is of high quality and can be further processed for direct sales or can be recycled to produce lower boiling products (naphtha and/or gasoline, furnace oil, etc.) and some additional high viscosity index distillate lube oil base stock.

Similar equipment to that illustrated in the drawing would be used when the feed stock is composed entirely of distillate. However, the product separation would be carried out somewhat differently. Thus fractionator 15 would be constructed and operated to separate a bottoms fraction heavier than furnace oil. A part of this fraction, which would comprise distillate lube base stock,

would be recycled and part would be subjected to treatment to prepare a finished lube oil, such as by dewaxing, fractionation and blending to form lubricating oils such as SAElO, SAEZO, etc. grade oils.

EXAMPLE I A Kuwait gas oil having the properties shown in column 1 of Table I was treated with hydrogen in the presence of a sulfided nickel-tungsten catalyst composited with a silica-magnesia cracking catalyst support which contained fluorine. The catalyst contained 25 percent nickel and tungsten and 2 percent fluorine. The reaction conditions (other than hydrogen ratio which was 10,000 s.c.f./bbl. of feed) are given in Table II. The results of these treatments are given in Table II. In column 1 of Table II no recycling of the product was carried out. In column 2 a bottoms fraction of the product boiling above 6 Table II 725 F. was recycled in the amount shown in the table.

Column No.

Table I 5 1 2 CHARGE STOCKS Sin le Rec cle (3011111111 N0. Fags y 1 2 3 Hydrocracking Conditions:

Temperature (Fresh Catalyst, F. 760 760 Pressure, p.s.i.g 2, 500 2, 500 Stock Space Velocity, Total Feed, v./h./v 1.0 1.0 Recycle Liquid Rate, Percent of Fresh Feed None 76 70.5% Yields, Percent by Volume of Fresh Feed: Kuwa t Kuwait 3 and C 2. 2 4. 4 Gas 11 s Oi Naphtha (Debutanized)- 12.3 22.5 Kuwa t plus plus Furnace Oil 50. 2 84. 5 Gas 011 29.5% Fractionator Bottoms 45. 4 4. 2 Kuwait Kuwait Dewaxed Light Lube Oil 725" F.) 7. 4 e 1.1

Deas- Deas- Dewaxed Lube Oil Base Stock 725" phaltcd phalted F 23.0 I 2.0 011 Oil 15. 0 l 1. 1 20 Ratio of Furnac aphth 4.1 3.8 Inspections-Dewaxed Lube Oil Base Stock: Inspection Date: Viscosity, SUV:Sec.'

Gravity, API 22. 6 22. 2 21. 8 155 89. 6 Viscosity. SUV: Se 210 F 45. 0 39.4 130", F... 158 Viscosity Ind 124 141 150 F. 117 141 210 F... 47. 4 56. 0 61. 7 Sulfur, Percent 2. 71 2. 81 2. 83 11 Obtained from small stream bled from recycle liquid. Nitrogen, Total, Percent 0.081 0. 066 0. 085 Carbon Residue, Ramsbottom, 4 6 0 56 It will be evident from the data presented in Table 11 Percent 0. 8 0. Distillation Vacuum Corrected to that a high quality lubricating oilproduct in. addition to 760 mm. Hg. at F.: furnace oil and naphtha can be simultaneously prepared 5 23% 35 "5% by the process of our invention. It is also to be noted 740 72 7 3; that when a part of the lubricating 011 product is recycled, 2%,? g 978 the furnace oil-to-naphtha ratio remains at substantially 984 the same high level even though a large amount of the product is recycled.

Table III Column No.

Charge Stock Kuwait Gas 70.5% Kuwait Gas Oil Plus 20% Oil Plus 29.5%

Kuwait uwa' Deasphalted Oil Deasphalted Oil Gas Oil Recycle Hydrocracking Conditions:

Temperature (Fresh Catalyst), F 731 751 729 750 Pressure, p.s.i.g 2, 500 2, 500 2, 500 2, 500 Space Velocity, Total Feed, v./h./v 1. 0 1.0 1. 0 1. 0 Recycle Liquid Rate, Percent of Fresh Feed 84 49 60 Yields, Percent by V01. of Fresh Feed:

2. 2 2. 9 1. 7 2. 5 5. 4 8. 6 4. 8 7. 4 49. 2 57. 4 44. 8 55. 5 50. 5 41. 2 55. 7 45. 2 Dewaxed Light Lube Oil Base Stock 5. 9 6. 3 6. 0 7. 3 Dewaxed Heavy Lube Oil Base Stock- 27. 2 17. 2 30. 4 22. 6 Wax 17.4 17.7 19.3 15.3 Ratio of Furnace Oil-to-Naphtha 9.1 6. 7 9.3 7. 5 Inspections:

Dewaxed Light Lube Oil Base Stock:

Viscosity, SUV:Sec.:

100 F--- 129 102 111 210 F 42. 3 40. 1 41. 7 40. 9 Viscosity Index 116 120 119 121 Dewaxed Heavy Lube Oil Base Stock:

Viscosity, SUV:Sec.:

100 F 450 376 678 451 210 F 62. 4 60. 0 74. 5 64. 6 Viscosity Index. 104 114 102 112 7 EXAMPLE 11 Two Kuwait gas oils blended with deasphalted residuum and having the properties shown in Table I, columns 2 and 3, were treated with hydrogen in the pres ence of a sulfided nickel-tungsten catalyst composited with a silica-magnesia cracking catalyst support which contained fluorine. The catalyst contained 25 percent nickel and tungsten and 2 percent fluorine. The results of these treatments are given in Table III (columns 1 and 2 showing treatment of the feed described in column 2 of Table I and columns 3 and 4 showing treatment of the feed of column 3 of Table I). The reaction conditions employed in all of these runs (with the exception of hydrogen rate which was 10,000 s.c.f./bbl. of feed) are given in Table III, including the rates at which components of the product boiling between about 725 and 850 F. were recycled.

It will be evident from the data presented in Table III that high quality lubricating oils of high viscosity index in addition to furnace oil, naphtha, etc., can be simultaneously prepared by the process of our invention. It will also be noted that this is accomplished while simultaneously obtaining a high furnace oil-to-naphtha ratio. Furthermore from a comparison of Tables II and III it will be noted that by treating a mixture of gas oil and deasphalted residuum in accordance with our invention, a marked increase in the furnace oil-to-naphtha ratio is obtained.

We claim:

1. The process for simultaneously producing a lubricating oil and a hydrocarbon fraction selected from the group consisting of furnace oil and lower boiling hydrocarbons by hydrogen treatment of a feed stock selected from the group consisting of a distillate hydrocarbon fraction which boils above about furnace oil (i.e., above about 650 F.) and which contains components boiling in the lubricating oil range and gas oil range and mixtures thereof with deasphalted residuum, said process being carried out by contacting the feed stock with hydrogen in the presence of a two-component catalyst comprising essentially a hydrogenating component composited with a cracking base having an activity above 25 on the Kellogg scale at a temperature between about 650 and 850 F., at a hydrogen partial pressure above about 1500 p.s.i., at a space velocity between about 0.2 and 10, thereby producing a hydrogen treated stock having substantial components boiling in the range of furnace oil and lower boiling hydrocarbons (i.e., below about 650 F.) and boiling above the furnace oil range (i.e., above about 650 F.), fractionating this hydrogen treated stock to obtain a fraction boiling below about 650 F. and another fraction boiling above about 650 F., which fraction contains lubricating oil components, recycling a portion of the fraction boiling above about 650 F. to the hydrogen treatment, recovering another portion of the fraction boiling above about 650 F. as lubricating oil base stock product and recovering the fraction boiling below about 650F. as furnace oil and lower boiling hydrocarbon product.

2. The process of claim 1 wherein the lubricating oil base stock product is further subjected to treatment for preparation of a finished lubricating oil.

3. The process of claim 2 in which the treatment for the preparation of a finished lubricating oil includes dewaxing.

4. The process of claim 1 wherein the cracking base is a siliceous cracking base.

5. The process of claim 4 wherein the siliceous cracking base has an activity above 35 on the Kellogg scale.

6. The process of claim 1 wherein the portion of the fraction boiling above 650 F. which is recycled to the hydrogen treatment is recycled at a rate of between about 15 and 250 percent based upon the gas oil portion of the fresh feed. 7. The process of claim 6 wherein the recycle rate is between about 33 and 230 percent based upon the gas oil portion of the fresh feed.

8. The process of claim 1 wherein the hydrogen partial pressure is between about 1500 and 3500 p.s.i.

9. The process of claim 1 wherein the cracking base is a silica-magnesia cracking base.

10. The process of claim 1 wherein the catalyst is comprised essentially of a sulfided-nickel-tungsten-halogen hydrogenating component composited with a silica-magnesia cracking base.

11. The process of claim 1 wherein the temperature is between about 700 and 825 F., the hydrogen partial pressure is between about 2000 and 2500 p.s.i. and the space velocity is between about 0.5 and 3.0.

12. The process for simultaneously producing a lubricating oil and a hydrocarbon fraction selected from the group consisting of furnace oil and lower boiling hydrocarbons by hydrogen treatment of a feed stock comprising a distillate hydrocarbon fraction which boils above about furnace oil (i.e., above about 650 F.) and which contains components boiling in the lubricating oil range and gas oil range mixed with deasphalted residuum, said process being carried out by contacting the feed stock with hydrogen in the presence of a two-component cata-lyst comprising essentially a sulfided-nickel-tungstenhalogen hydrogenating component composited with a silica-magnesia cracking base having an activity above 35 on the Kellogg scale at a temperature between about 700 and 825 F., at a hydrogen partial pressure between about 2000 and 2500 p.s.i., at a space velocity between about 0.5 and 3.0, thereby producing a hydrogen treated stock having substantial components boiling within the range of furnace oil and lower boiling hydrocarbons (i.e., boiling below 650 F.), and boiling above the furnace oil range (i.e., above about 650 F.), fractionating this hydrogen treated stock to obtain a frac tion boiling below about 650 F. and another fraction boiling above about 650 R, which fraction includes lubricating oil components, recycling a portion of the fraction boiling above about 650 F. to the hydrogen treatment at a recycle rate of between about 33 and 230 percent based upon the gas oil portion of the fresh feed, subjecting another portion of the fraction boiling above 650 F. to dewaxing treatment for preparation of a finished lubricating oil, recovering the finished lubricating oil as product and recovering the fraction boiling below 650 F. as furnace oil and lower boiling hydrocarbon product.

References Cited by the Examiner UNITED STATES PATENTS 2,923,680 2/1960 Bushnell 208264 2,944,014 6/1960 Hoffman 208264 3,078,221 2/1963 Beuther et a1. 208264 3,142,635 7/1964 Coonradt et al 208211 ,DELBERT E. GANTZ, Primary Examiner.

S. P. JONES, Assistant Examiner.

Claims

1. THE PROCESS FOR SIMULTANEOUSLY PRODUCING A LUBRICATING OIL AND A HYDROCARBON FRACTION SELECTED FROM THE GROUP CONSISTING OF FURNACE OIL AND LOWER BOILING HYDROCARBONS BY HYDROGEN TREATMENT OF A FEED STOCK SELECTED FROM THE GROUP CONSISTING OF A DISTILLATE HYDROCARBON FRACTION WHICH BOILS ABOVE ABOUT FURNACE OIL (I.E., ABOVE ABOUT 650*F.) AND WHICH CONTAINS COMPONENTS BOILING IN THE LUBRICATING OIL RANGE AND GAS OIL RANGE AND MIXTURES THEREOF WITH DEASPHALTED RESIDUUM, SAID PROCESS BEING CARRIED OUT BY CONTACTING THE FEED STOCK WITH HYDROGEN IN THE PRESENCE OF A TWO-COMPONENT CATALYST COMPRISING ESSENTIALLY A HYDROGENATING COMPONENT COMPOSITED WITH A CRACKING BASE HAVING AN ACTIVITY ABOVE 25 ON THE KELLOGG SCALE AT A TEMPERATURE BETWEEN ABOUT 650* AND 850*F., AT A HYDROGEN PARTIAL PRESSURE ABOVE ABOUT 1500 P.S.I., AT A SPACE VELOCITY BETWEEN ABOUT 0.2 AND 10, THEREBY PRODUCING A HYDROGEN TREATED STOCK HAVING SUBSTANTIAL COMPONENTS BOILING IN THE RANGE OF FURNACE OIL AND LOWER BOILING HYDROCARBONS (I.E., BELOW ABOUT 650*F.) AND BOILING ABOVE THE FURNACE OIL RANGE (I.E., ABOVE ABOUT 650*F.), FRACTIONATING THIS HYDROGEN TREATED STOCK TO OBTAIN A FRACTION BOILING BELOW ABOUT 650*F. AND ANOTHER FRACTION BOILING ABOVE ABOUT 650*F., WHICH FRACTION CONTAINS LUBRICATING OIL COMPONENTS, RECYCLING A PORTION OF THE FRACTION BOILING ABOVE ABOUT 650*F. TO THE HYDROGEN TREATMENT, RECOVERING ANOTHER PORTION OF THE FRACTION BOILING ABOVE ABOUR 650*F. AS LUBRICATING OIL BASE STOCK PRODUCT AND RECOVERING THE FRACTION BOILING BELOW ABOUT 650*F. AS FURNACE OIL AND LOWER BOILING HYDROCARBON PRODUCT.