US2603587A - Propane fractionation of lubricating oil stocks - Google Patents

Description

Patented July 15, 1952 PltdPAN E FRACTIONATIO'N LUBRI- CATING OIL STOCKS Russell K.

Simm's, Bartlesville, kla., assignor to Phillips Petroleum Company, a corporation of' Delaware I Application January 4, 1950, Serial No. 136,124

, 16 Claims. (01. ice-14.45)

This invention relates to propane fractionation of lubricating oil stocks. In one aspect, it relates to a method for the treatment of asphaltcontaining lubricating oil stocks for the simultaneous separation of lubricating oil fractions and' the removal of a'sphaltic material. In still a more specific aspect, it relates to a process for the separation and the recovery of lubricating oil fractions from crude lubricating oil stocks containing some asphaltic and resinous material by fractionation withpropane wherein the asphaltic and resinous materials are precipitated and removed from the lubricating oil.

The asphalt content of a crude oil may conveniently be defined as the per cent of residue from the vacuum distillation of a crude oil, said residue having a maximum A. S. T. M. D243-36 penetration of 100 at 'l'l" F. For Oklahoma City crude oils this asphaltic residue constitutes about 2 per cent by weight'of the crude oil.

By the term"'low-asphalt crude oil, I mean crude oils containing'a maximum of about 5'per cent asphalt by weight as determined by the above-mentioned A. S. T. M. method. Such a low-asphalt-containing crude oil maybe distinguished from conventional Lasphaltic crude oils such as California crudes which contain from '12 per cent to 65 per centaSphalt, and from Wyoming and Arkansas crude oils which contain about 30 percent asphalt. f I

Deasphalting petroleum oils and more particularly reduced crude oils from which distillate lubricating oil fractions have been removed is old in the art. Such operations are usually carried out at temperatures between about 70. and 140 F. to take advantage of the precipitating action of propane on the heavy asphaltic constituents of the oil. It has also been recognized for many years that a fractionating effect can be obtained with propaneoil mixtures at temperatures ranging from about 140 F. up to the crtical temperature of propane or higher. Utilizing the unique properties "of liquid propane whereby increasing temperatures result in progressive rejection of hydrocarbons insuch a manner that the higher molecular weight components and the more aromatic and naphthenic components are separated first and the lighter components and more 'paraffinic hydrocarbon last, a combination of low temperature distillation'and solvent ex-. traction is achieved. However, due to the diffrculties involved in workingat high pressures and in close proximity to the .criticaltemperature of propan commercial exploitation-was unknown until quite recently.

It has been found, however, that some low asphalt-content reduced crude lubricating oils may be fractionated continuously by liquid propane under high pressure and at a relatively high temperature, while other such crude oil stocks can be fractionated only for very short periods of time. In this latter case it has been found that the fractionating equipment became plugged with a deposit of asphaltic material. This asphaltic material has apparently been precipi-' tated from the oil upon-contactwith the high temperature propane. It should be mentioned that the oils in queStionwere low asphalt-containing oils and did'not differ significantly from each other in total asphalt content, as conventionally determined. Why some caused plugging trouble and others did not is not clearly understood. 1

An object of my invention is to devise a process in which a low asphalt-containing reduced crude lubricating on stock is fractionated for the separation and recovery of lubricating oil fractions.

Another object of my invention is 'tof'devise a process for the separation and removal of asphaltic resinous materials from crude oil stocks containing these materials and the simultaneous fractionation of the lubricating oil and-constituenm g I Still another object of my invention is to de-' vise a process in which precipitated asphaltic and resinous materials may be removed from a propane lubricating oil fractionation process without precipitating of the asphaltic and resinous material in such a manner as to plug the treating apparatus.

Still other objects and advantages of my process will be obvious to'those skilled in the art upon reading the following disclosure which taken with the attached drawing forms a part of this specification.

In preparing to apply the above-mentioned unique properties of liquid propane to actual commercial fractionation of certain grades of lubricating oils from residual stocks, a hitherto unrecognized problem was encountered. Upon fractionating some Mid-Continent reduced crude lubricating-oil stocks with liquid propane in a countercurrent contacting tower at a propaneto-oil volume ratio of about 7:1 with temperatures ranging from about 195 F. at the top to about F. at the. bottom of the tower, an SAE '40 oilflwas continuously separated 'in the overhead product... On the other hand, when a very similar Mid-Continent reduced crude 'lubrithis third phase when first formed was 'suflie ciently fluid to flow nearly to thebottom of the column before the ascending propane had washedit suiflciently to cause it to set'to a hard cake. Upon continued operation, this cake builds up in the column until complete closure of the column occurs. Why one low asphaltcontaining oil should deposit its asphalt while another does not when the two oils contain similar amounts of asphalt is not definitely known. 1

' In a study'of three well-known Mid-Continent crude oils which havet-long'ibeen recognized as excellent sourcesof lubricating-oil stocks-hard deposits were formed when treating two of these stocks with liquid propane while the third was fractionated with propane continuously and without difiiculty. It has alsobeen foundlthat some 'West Texas lo.w asphalt-content reduced crude oils can be. continuously fractionated with propane while others cannot. It isth'erefore real ized that propane-fractionation cannot be'universally'applied togall so-called low asphalt-content reduced crude lubricating oil stocks; In my improved process, I use a vertically .disposed elongated separation zone .fllled with a downwardly moving bed of particulate material which may be used as packing for the separation zone. The. particulate material is preferably spherical-shaped, although irregular shapes may be used, and has a-diameter. in the range of about A" to 1". Hereinafter, this flowable particulate material will be called pebbles. may be formed from refractory material such as alumina or silicon carbide, it will be founddesirableto utilize an-adsorptive material such as silica or adsorptive alumina. Y i In the drawing, the figure represents diagram? matically, partly in section, and partly in ele'vation, oneform of apparatus in which the process of my invention may be practiced. -Referring .now to the drawing, a contacting vessel is an elongated, cylindrical-shaped vessel having ia conical-shaped bottom. This vessel is filled with pebbles 3 and these pebbles .are held :up some distance from the bottom by 'aconical .fllter member 12. From the apex of this conical memher [2 a pipe |3leads to a pebble flow controller apparatus 4. -A'source of power I5 is adapted to operate this pebble flow controller apparatus.-

Pebbles leaving, the apparatus line H into the bottom of a pebble elevator l8 which is adapted to elevate such particulate material from one point to a higher point. :This elevator then can discharge the'elevated material into a conduit l9 which-in turn discharges'the material into the top of .a regeneration vessel 2|.

The regeneration vessel 2| is equipped with numerous inlet and outlet pipe connections. Pipes 23 .and 24 are intendedfor passage of gaseous combustible material from an outside source into' the regeneration zone. Pipe 25 is for removal of combustion products from the .top'of this vessel. Combustion'product's not desired in" 75 These pebbles butin some instances,

gel; activated charcoal,

the process may be vented or otherwise disposed of by passagefrom pipe 25 through pipe and the flow through pipe 35 is controlled by a damper or other suitable valve control means 31. Combustion gases to be used in the process flow from pipe 25 under the influence of a compressor or blower 21 into a pipe2'9.- From this pipe these gases may bepassed into the regeneration zone through one or more inlet pipes 33. These inlet pipes 33 are provided with some valves 34 so that one or more of the pipes may be closed to the l flow of'ga'ses. A pipe 3| is for passage of air or other combustion-supporting gas into the pipe 29. A by-pass line 28'connects with the discharge pipe of blower 21; for passage of combustion gas through a valve 51, cooler 53, a valve 55, and a line 4 linto the bottom outlet pipe 39 to regeneration vessel 2|. Under certain conditions of op- .eration', steam or othercooling material may be desired to be passed through line 4| into the leg 39 50 asto cool the pebbles andserve as seal between zones and 2|,. and under such conditions,-said steam or other cooling material is passed through a pipe 43 through a valve 61 into the pipe 4|. Pipe 421s connected with the body of the regeneration zone 2| at-a point somewhat below the inlet pipes 23.; This pipe 42 is intended for use inwithdrawing a portionor all-of the.

fiue gas or steamintroduced into the regeneration zone 2| through pipe Aland leg 39. I

To the bottom ofthe leg 39 is attached a heat exchanger: apparatus 45 which in. turn is con: nected by conduit to. the, .top of: the separation vessel Thisheat exchanger v may contain tubes through which a.v heat exchange fluid may pass in indirect heat exchan'geiwith the-particulate materlal flowing by' 'gravity through the. spaces between the tubes; Pipe Sis-connected for passage of .fluid from the'separation vessel.

through a pipe:9,'avalve' 'llyand va pipe |0 into the tubes .of' the exchangerwAipipe 4'! which is equipped witha back. pressure regulator 49 is intended for passage 10f cooling fluid fromjthe tube section of the-exchanger 45. In case fluid from the top of the: separation zone I1 is notipassed through the exchanger.45;;a pipe,;'|3.is provided for removal, ofthis productfromthe system.; In

case extraneous, coolingfluid is desired to, be

passed through the tube-section of the exchanger 45, such cooling fluid is passed from-pipe 69' through pipe |0 into, the exchanger. Whenan extraneous cooling fluid is used at this point, the back pressure regulator 49*may or may not be used.

Apparatus 5| is a temperature difierential controller recorder assembly having a connection leading to a thermocouple 52 in the top of the vessel and a connection leading to a thermocouple 54in the bottom of the vesselyli This temperature differential controller regulates the.

power supplied to prime mover l5 and thus regulat'e's the speed of the pebblesflow controller; i

In the operationfofi my process-the apparatus is filled with a desiredhparticulate material such as diameter alumina pebbles through a pebble makeup inlet line '20i Sufficient pebbles'are' added through the pipe 20. to? fill the separation vessel the heat-exchanger 45, andthe regeneration vessel" 2|. Whenthese several vessel and connected conduits are filled'with pebbles, the elevator I8 is started and the pebble flow cone troller apparatus I4 is also started so: that peb'-- l3, flow'controller' bles may flow through con'duit 4, conduit |1,'and flll'the elevatori 8. Additional pebbles will of course be added through-pip'e '20 5. to fill the pebble-containing system with. the desired amount of pebbles. I

An inert gas, such as nitrogen, an. oxygen-free flue gas, or steam, may be introduced into the system through pipe 43, valve 61, and pipe 4| to. serve as sealing fluid between chambers 2l' and. l' and a cooling medium for the pebbles.

Liquid propane is introduced into the separation vessel, through a propane inlet pipe I. Sullicient propane is added that thelevel of the liquid propane will rise in the exchanger 45 to the point at which. pipe 41' is connected and that the propane-to-oil'feed stock ratio is between thelimits of 4:1 to 14:1. The propane may also flow through the conduit l3", M, and through conduit l1 into the elevator column. In some cases, it may be desirable to inject a sealing fluid into conduit l3, ll, or elevator i8-,to prevent or reduce the flow of hydrocarbon materials from the separation zone. Such a szaling fluid may be steam added through line A combustible mixture of a gas and air may be injectedinto the regeneration zone through the pipes 24 for heating of the pebbles in the zone to a temperature such that when an excess of oxygen is added, the asphaltic material on the pebbles will burn. Additional gas and air are introduced into the regeneration zone through the pipes 23 for further heating of the pebbles.

The gases of combustion then leave the regeneration zone through pipe 25 and are circulated by the blower 21 through pipes 28 and29. That flue gas passing, through. pipe 23 passes on through valv 51, cooler 53', valve the leg 39. In this leg 39 hot pebbles from the regeneration zone are flowing downward and the pebbles are then cooled by countercurrent contact with the upward flowing cool combustion gases. These gases after cooling the pebbles may be removed from the regeneration zone through pipe 42'.

Heated pebbles pass through. leg 39, thence 45' wherein the found necessary so that the pebbles entering separation zone I will supply; the desired amount of heat to this zone. Under certain conditions of operation, the temperature to be maintained in from regeneration zone 2! through heat exchanger the top of this zone maybe of the order of from 190-200" F. Propane for continuous operation may then be introduced into the column through the propane inlet line 1. Th entrance of the hot pebbles continuously into the top of the column then continuously heats the propane as it rises upward in the column, and the propane in the top of the column is maintained at about 190-200 F. The warmed propane then leaves the column through line 8 and out through pipe 13 or through lines 9, l0, exchanger 45, and pipe 41. The asphalt-containing lubricating oil stock may be introduced through inlet line 5. When the lubricating oil contacts the propane in. the column, the lower molecular weight oily hydrocarbons andthe more paraifinic hydrocarbons dissolve in the propane as an oil-in-propane phase. Since the hot pebbles lose their heat progressively on descending in the column, the propane is heated progressively less and less at points successively nearer the bottom of. the column. At the point oi highest temperature in the column, the propane possesses the greatest precipitating tendency for the asphaltic and resinous material. However, at the point of inlet of the crude lubricating oil stock, the above-menpebble flow controller 55, and pipe 4! into temperature may be adjusted as p tioned third, or asphaltic phase usually precipi tates. upon contact the propane at the temperature' of the. column at that point. In my process. this asphaltic and resinous. material preci'pitates upon the. surface of the. pebbles. the lower portion of the column, which is operated at relatively lower temperatures, the propane is a better solvent for oil, and thus the ascending propane washes this more oily material from the. surface of the pebbles. In like manner, at points higher up the column. and at progressively higher temperatures, the. precipitating, action. of the. higher temperature. propane tends. to throw out of solution the lessparaiiinic and more aromatic resins and asphaltic materials. At least. some of this precipitated material is re.- tained on the surface of the pebbles and as they flow downward in the, column is washed by the ascending propane. 7

In case only a small amount of asphaltic mate.- rial is present in the oil stock, ing of asphalt acquired by the pebbles. is rela'-' tively small, and some of the asphalticmaterial may be retained in an oily solutioninsoluble in propane. This oil-rich liquid then flows downward in the column along with the pebbles. Upon reaching the conical member I2, this liquid then drains through perforations: IS in the cone l2 andaccumulates in the vicinity of the apex of the vessel 1 as an oil-rich liquid phase. This oil-rich phase containing at least somepropane in solution is withdrawnv through a line I I and is conducted to a propane; recovery step, not shown, or to another propane fractionation step similar to that explained as occurring in column. 1.

In such. a subsequent step, the temperature,

pressure, and. propane to oil ratio conditions will be varied in'such, a manner as to remove overhead a desired fraction of the bottoms product from line I l.

The pebbles with their asphalt coating flow from the bottom of the conicalmember [2 through the conduit l3, the pebble flow controlling apparatus M, pipe l1, and into the elevator 8. The elevator raises or lifts the asphaltcoated pebbles and discharges them through conduit l9 into the top of the regeneration vessel 2|.

In. some cases, burning of combustible fuel from inlets. is desirable in order. to raise the temperature of the pebbles to such a temperature. that the free oxygen entering the vessel through, one or more lines 33 will consume the asphaltic and resinous matter'irom the pebbles. In order that all of the combustion of the asphaltic. and the. resinous material will. not occur at one point in the column, with possible overheating of the pebbles, several points, of inlet of combustion-supporting gas 33 are provided. Gases of combustion leave. the regeneration zone. through the pipe 25. and at least a portion is transferred by blower 121 into line29, in which some air through pipe: 31 is introduced. The proportion of air added at. this point is so controlled that the oxygen content is maintained at 2. sufiiciently low level that overheating of the pebbles in the regeneration zone will not occur. If sufiicient heat is generated in the upperportion of the regeneration zone and in the. combustion section to maintain the pebbles at a combustion temperature relative to the oxygen content of the combustion-supporting gas entering through lines 33, the pebbles do not need to be heated further in the region of lines 23. Under such conditions, the combustible gas mixture may be introducedinto this column through the the layer, or coat-' lines 23 only during such times as is required for the system to acquire an operational equilibrium and then, as mentioned, if combustion is complete at about the center of this column, the combustiongas mixtures from lines 23 may be closed off. V

The bottom portion of the regeneration zone and the leg 39, are used as a pebble cooling section. Pebbles in this section may be cooled by an inert gasor by steam. Since the entire apparatusis maintained under a relatively high operating pressure, it may be preferable to pass a portion of the combustion gases from line 25 through pump 21, line 28, valve 51, cooler 53, valve'55, and on through pipe M into this cooling section. In case steam or cooling gas from an extraneous source is used as a cooling medium, valve 55 may be closed and the cooling medium may be introduced into the leg 39 through the pipe 43, valve 61, and the pipe 4I. All or a portion of the steam or gases of combustion used for cooling, may be removed from the regenerator through the outlet 42. The regeneration operation taking place in the top of this vessel is not interfered with.

The cooling medium which, enters through line ll is of such temperature and volume that the pebblesare cooled to such an extent that the final cooling may be properly carried out in the exchanger 45. In case the overhead product from the separation zone I is to be separated into its propane and oil components, this material is passed through lines 8, 9, and I and into the heat exchanger 45. The heated overhead product then leaves the exchanger through line 41 and is passed through a back pressure regulator valve 49, and at this point the propane may be flashed from the oily material to effect the separation. The propane may be condensed and returned to the system, while the oil may be passed to storage or to a subsequent treating step, as desired. 7 V p The oil-rich phase is withdrawn from the bottom of the separation zone I at such a rate as to maintain therein a relatively low level of this materiaL- This oil-rich phase is identified in the drawing byreference numeral 59. Reference numeral BI identifies the propane phase containing dissolved oil which floats on top of the oil-rich phase 59. Some oil-rich phase from the bottom of the separation zone I fills the conduits I3 and I1, and the pebble flow control apparatus I4, and the lower portion of the elevator I8. Reference numeral 63 is intended to identify the level of the oil-rich'phase in the elevator.

The temperature differential in the separation zone I may be controlled automatically at a predetermined value by meansof a temperature difierential controller recorder. For example, if a 30 temperature differential between th'etop and bottom is desired and this differential increases by a temperature increase in the top of the column occasioned by too hot pebbles, this recorder control apparatus operates to slow down the'fiow of pebbles. In like manner, if the difierential decreases for somereason, this controller operates to increase the flow of pebbles so that more pebbles will be introduced into the top of the separation zone.

Example about 800 F. is introduced into .the separation zone through line. 5. Liquid propane is introduced into this zone through line I. The ratio of the liquid propane to the lubricating oil stock is between 6:1 and 7:1. The top'of the column is maintained at atemperature between 19 0 and 200 F. while the bottom of the column is-maintained at a temperature between and F. The temperature of the propane introduced into the column through pipe Tis maintained. at such a value that the bottom of the columnwill have the temperature between 145 and 175 F. and the charge oil is fed at such a' temperature that the feed point may be maintained at a temperature between column top and bottom. Pressure on the entire system is maintained between 600 and 700 p. s. i. When'operating under these conditions; an oil having the viscosity characteristics of an SAE 40 50 and dissolved in propane is taken off through line 4! as overhead product. This propane oil solution is flashed on passage through valve 49 and final traces of propane may be stripped from the oil if desired, to produce an oil having the above-mentioned SAE viscosity characteristics, Sufiicient air or other free oxygen-containing gas is added to the gases of combustion through line 3I for regeneration purposes that the oxygen content of the gas entering the regeneration column through lines 33 is from 2-5 per cent.

The elevator I8 may be a conventional bucket elevator or any other type of elevator which may be entirely enclosed and is suitable under the required operating conditions. The pebble feeder or flow controller apparatus I4 may be any suitable type of apparatus desired.

While my process has been so far described with pebbles flowing downward by gravity contacting gases or liquids countercurrently and flowing upward, these directions of travel are not necessarily critical. For example, in the regeneration zone, the pebbles may fiow downward by gravity, while the oxygen-containing combustion gas may pass through the pebble bed in a horizontal direction in the well-known cross-flow type of chamber.

Under some conditions, it may be desirable to remove the asphaltic deposit from the surface of the pebbles at as low a temperature as possible. Oxidation catalysts, such as vanadium pentoxide, may be incorporated in the pebble composition, and under such conditions the asphaltic and resinous material may be burned from the surface of the pebbles at a lower temperature than when such a catalyst is not used.

The apparatus shown on the drawing and described hereinabove comprises only a fractionation zone and a pebble regeneration zone, with interconnecting apparatus. However, when the crude lubricating oil feed contains an appreciable quantity of aromatic hydrocarbons, it-may be highly advantageous to use an adsorptive type of pebble such as silica gel, to remove by adsorption at least a portion of the aromatic content of the feed as well as removing the resinous and asphaltic materials. By this means it is possible to increase the parafilnicity ofthe overhead product. When this modification is employed, a third chamber positioned below separation zone I is employed. In this third chamber the adsorbed aromatic materials may be stripped from the pebbles prior to their passage to the regeneration zone for removal of the asphaltic and resinous matter by oxidation.-

It will be obvious to those skilled in the art "and variations.' Such variatio The apparatus must be constructed towithstandsafely an operating pressure of at least 600-700 p. s. i.

I-Iaving disclosed my invention, I claim:

I. In the propane fractionation of lubricating oil constituents from low asphalt-content reduced.

crude lubricating oil stocks with liquid propane wherein solid asphaltic material precipitates upon initial contact with the propane and adheres to and plugs the fractionating apparatus in the region adjacent and below the raw feed entry point, a process for continuously carrying out this fractionation operation without precipitating said asphalt and plugging said apparatus comprising maintaining a moving bed of particulate material in a first, zone, said particulate matter being within the size range of A inch to 1 inch in diameter, maintaining a body of liquid propane containing dissolved oil in said zone, maintaining a body of an oil-rich phase below said body of propane containing dissolved oil in said zone, said bodies meeting at a common interface, introducing'a stream of liquid propane into said body' of propane containing dissolved oil at a point near said common interface, introducing a stream of said low asphalt-content reduced crude lubricating oil stock into said body of propane containing dissolved oil at a point above said point of introduction of propane, maintaining the top of said body of propane containing dissolved oil at a higher temperature than that of the oil-rich phase, removing propane containing dissolved oil from and recovering the oil therefrom, removing the oil-rich phase from the bottom of said zone and removing particulate material containing adhering asphalt from the bottom of said zone.

2. In the process of claim 1 introducing the particulate material to the top of said .bed at a temperature higher than the temperature of the stream of liquid propane introduced into said body of propane containing dissolved oil.

3. In the process of claim 2, maintaining the top of said body of propanecontaining dissolved oil at a temperature between the limits of 190 to 200 F. and the bottom thereof at a temperature between the limits of 145 to 175? F. at a pressure between the limits of 600 to 700 pounds per square inch.

a. In the process of claim 3, introducing the liquid propane and the lubricating oil stock into said propane containing dissolved oil in the ratio between the limits of 4 to l and 14 to l by volume.

5. In the process of claim 3 introducing the liquid propane and the lubricating oil stock into said propane containing dissolved. oil in the ratio between the limits of 6 to l and 7 to l by volume.

6. In the propane fractionation of lubricatin oil constituents from low asphalt-content reduced crude lubricating oil stocks with liquid propane wherein solid asphaltic material precipitates upon initial contact with the propane and adheres to and plugs the fractionating apparatus in the region adjacent .andhbe'low the a w feed entry point, a process for continuously carrying but this fractionation operation without precipitat ing said asphalt and zplugging said apparatus comprising maintaining a;downwardFmoving bed of particulate 'material; in a treating zone, said particulate'matter being within the size range of inch to 1 inch in diameter, maintaining a body of liquid propane containing dissolved oil in said zone, maintaining a body of an oil-rich phase below said body of propane containing dissolved oil in said zone, said bodies meeting at a common interface, introducing, a stream of liquid propane into saidbody of propane containing dissolved oil at a point near said interface, introducing a stream of said low asphalt-content reduced crude lubricating oil stock into said body of propane containing dissolved oil at a point above said point of introduction of propane, maintaining the top of said body of propane containing dis: solved oil at a temperature between the limits of 190 to 200 F. by the introduction of heatedparticulate material into the top of said body of propane containing dissolved oil, withdrawing particulate material with adhering asphalt from v the bottom of said downward moving bed at a temperature between the limits of to F., removing propane containing dissolved oil from the top of said zone and recovering the oil, removing oil-rich phase from the bottom of said zone and recovering the oil; burning said adhering asphalt from said particulate material, cooling the hot particulate material and recycling as said heated particulate mterial.

. '7. In the process of claim 1, maintaining the volumeratio of propane to oil introduced into said zone between the limits of 4 to 1 and 14 to 1. 8. In the process of claim '7, maintaining the pressure in said first zone and in said asphalt burning operation between the limits of 600 to 700 pounds per square inch.

9. In the process of claim 8, stripping the hot particulate material of combustion-supporting to and plugs the fractionating apparatus in the region adjacent and below the raw feed entry point, a process for continuously carrying out this fractionation operation without precipitating said asphalt and plugging said apparatus comprising maintaining a downwardly moving stream of solid particulate material in a treating zone, said particulate matter being within the size range of inch to 1 inch in diameter,

introducing liquid propane into the lower partof said zone and said low asphalt-content oil into a higher part of said zone, maintaining progressively lower temperatures from the top to the bottom of said zone, removing a liquid comprising propane containing dissolved oil from the top of said zone, withdrawing particulate material vith adhering asphalt fromthe bottom of said treating zone, and separately removing a liquid oil-rich phase from the bottom of said zone.

11. The process of claim 3 wherein the particulate material is non-hydrocarbonaceous matter.

12. The process of claim 11 wherein the particulate material is refractory alumina.

13. The process of'claim 11 wherein the particulate material is silicon carbide.

14. The process of claim 9 wherein the particulatematerial is nonhydrocarbonaeeous matter.

- 15 The process oficlaimiiwherein the particulate material is alumina. v

16. The process of c1aim'14 wherein the particulate material is silicon carbide. V

RUSSELL K. SIMMS.

12 REFERENCES CITED The following referenoee ai-eof record in the me of this patent: 7

Number UNITED s 'rEgPA NTs Name 1 I Date Weeks etal; Jan. 16, 1945

Claims (1)

1. IN THE PROPANE FRACTIONATION OF LUBRICATING OIL CONSTITUENTS FROM LOW ASPHALT-CONTENT REDUCED CRUDE LUBRICATING OIL STOCKS WITH LIQUID PROPANE WHEREIN SOLID ASPHALTIC MATERIAL PRECIPITATES UPON INITIAL CONTACT WITH THE PROPANE AND ADHERES TO AND PLUGS THE FRACTIONATING APPARATUS IN THE REGION ADJACENT AND BELOW THE RAW FEED ENTRY POINT, A PROCESS FOR CONTINUOUSLY CARRYING OUT THIS FRACTIONATION OPERATION WITHOUT PRECIPITATING SAID ASPHALT AND PLUGGING SAID APPARATUS COMPRISING MAINTAINING A MOVING BED OF PARTICULATE MATERIAL IN A FIRST ZONE, SAID PARTICULATE MATTER BEING WITHIN THE SIZE RANGE OF 1/4 INCH TO 1 INCH IN DIAMETER, MAINTAINING A BODY OF LIQUID PROPANE CONTAINING DISSOLVED OIL IN SAID ZONE, MAINTAINING A BODY OF AN OIL-RICH PHASE BELOW SAID BODY OF PROPANE CONTAINING DISSOLVED OIL IN SAID ZONE, SAID BODIES MEETING AT A COMMON INTERFACE, INTRODUCING A STREAM OF LIQUID PROPANE INTO SAID BODY OF PROPANE CONTAINING DISSOLVED OIL AT A POINT NEAR SAID COMMON INTERFACE, INTRODUCING STREAM OF SAID LOW ASPHALT-CONTENT REDUCED CRUDE LUBRICATING OIL STOCK INTO SAID BODY OF PROPANE CONTAINING DISSOLVED OIL AT A POINT ABOVE SAID POINT OF INTRODUCTION OF PROPANE, MAINTAINING THE TOP OF SAID BODY OF PROPANE CONTAINING DISSOLVED OIL AT A HIGHER TEMPERATURE THAN THAT OF THE OIL-RICH PHASE, REMOVING PROPANE CONTAINING DISSOLVED OIL FROM AND RECOVERING THE OIL THEREFROM, REMOVING THE OIL-RICH PHASE FROM THE BOTTOM OF SAID ZONE AND REMOVING PARTICULATE MATERIAL CONTAINING ADHERING ASPHALT FROM THE BOTTOM OF SAID ZONE.

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