US2083511A - Refining mineral oil - Google Patents

Description

June 8,1937.

'- M. H. TUTTLE 'REFINING MINERAL OIL Filed hov. 20; 19:53 4 Sheets-Sheet 1 INVENTOR. 4 lVa/rdmHM/e MM f ATTORNEYS.

June 8, 1937. "Mn. TUTTLE 2,083,511

REFINING MINERAL on. v

W e 4 \MN a B Q -..0 5 I u l wMN m 2 Wmm m w WWW MM m N mw wn a .w i F INVEN TOR.

A TTORNEYS.

June '8, 1937.

M. H. TUTTLE I mum numann. p11.

4 Sheets-Sheet 3 Filed Nov. 20. 1933- R. W5 m n wr I. fflywA m.

QNN

June 8, 1937 MjH. TUTTLE REFm I-Ns MINERAL on.

Filed Nov. 20, 1955 4 Sheets-Sheet 4 Patented June 8, 1937 REFINING MINERAL oI L Malcolm H. Tuttle, New Rochelle, N. Y., assignor to Max B. Miller & 00., Inc., New York, N. Y., a corporation of Delaware I Application November 20, 1933 Serial No. 698,746

6 Claims.

The present invention has to do with refining mineral oils by means of solvents.

This application is based upon subject-matter divided out of the present inventors copending application Serial No. 623,483, filed July 20, 1932, and also relates to certain modifications of the examples disclosed in that prior application.

Mineral oils consist principally of intimate mixtures of compounds of carbon and hydrogen in 10 varying proportions. Certain of these compounds are especially useful and suitable for lubricating oil, for instance for internal combustion engines and will be referred to as parafllnic. The other compounds are useful for other purposes but un,--

desirable in lubricating oils and will be referred to as naphthenic.

The solubility of pure paraflinic oil compounds in certain solvents differsfrom the solubility of naphthenic oil compounds in those solvents and it has been proposed to utilize this selective action for separating a mixture of parafflnic and naphthcnic oils, as exists in a mineral oil, into fractions. However, asolvent for naphthenic oil, such as nitrobenzene, which has a limited solvent power for pure paraflinic compounds, in the presence of naphthenic compounds forms a mixture in which the paraflinic compounds have a relatively high degree of miscibility or solubility. Further addition of solvent to themineral oil mixture to remove more of the naphthenic compounds carries additional parafiinic material into solution so that an attempt to improve the purity of the paraflinic compounds results in both a loss of paraiilnic material and a contamination of the naphthenic compounds. -In other words the improvement in the quality of one type of compounds can only be obtained where a single type of solvent is employed, by a lowering of the quality of the other type and is accompanied by a loss in yield 'of the high quality compounds of the flrsttype.

In accordance with the present development the quality of each class of constituents, parafiinic or naphthenic, may be improved 'up to the 'point of producing an excellent yield of practically'pure compounds of each type desired, without ail'ecting the quality of the other class; that is, additional naphthenic material may be removed from the mineral oil without loss of parafiinic' oil. It is preferred to employ two solvents having a limited miscibility in each other, one of which is a solvent for the parafllnic compounds and the other for the naphthenic.

Through the present invention it becomes possibe to produce the final extract of each type of oil in equilibrium with the solvent for the opposite type oil: 1. e., the final extract of'the naphthenic fraction is accomplished with fresh paraffinic solvent and the final extract of the paraflinic fraction is accomplished with fresh naphthenic solvent. p

A feature ofthe present invention resides in providing improved apparatus to continuously counterfiow the solvents and feed the oil, which is to be treated, at an intermediate point where it is subjected to the action of the counterfiow- 10 ing solvents. When the initialseparation is made in equilibrium with the charged oil, the composition of each layer is governed to some extent by the composition of the charged oil as well as by the ratio of solvents employed so that the par- 5 aflinic layer then contains an appreciable quantity of naphthenic material and the naphthenlc layer contains some paraflinic material. The present invention provides for separating the oil to be treated and purifying both layers without loss'of 20 oil constituents. i

It is also possible to adapt the counterfiow principle to batch treatment whereby the oil to be treated is brought into contact with both solvents so that a division into naphthenic and paraffinic 25 layers occurs.

In either the continuous or batch treatment, purification of the resulting fractions without loss of oil desired in that fraction may be accomplished by washing the naphthenic layer, includ- 30 ing naphthenic solvent and removed from the other layer, with the paraiiinlc solvent and the paraflinic layer, including paraflinic solvent and removed from the first-mentioned layer, with naphthenic solvent,'and separately recovering the 35 solvents from the washed layers to produce the paraifinic and naphthenic fractions. The relatively fresh solvents used for the final washings, together with the materials taken intosolution, may be used for washing less pure fractions at 40 points preceding the final washings. The extent of washing and the amounts of solvents employed may varywith the quality of each type of oil desired and oil to be treated.

The present development is especially useful with crude, or asphalt containing oils, or oils which have been topped (distilled) to remove low-boiling fractions such as gasoline and kero sene, but which still contain asphalts, although it is also useful in connection with other mineral 50 oils.

A feature of the invention resides in the provision of novel and improved apparatus for the purposes indicated.

A further featureof the invention resides in p naphthenic solvent enters the apparatus adjacent the provision of apparatus in which a given layer may be treated repeatedly with solvent for constituents which are impurities in that layer. the solvent being fresher or stronger in each succeeding treatment, so'that eventually that layer is treated with substantially pure solvent adapted to remove or strip the remainingsmall amountsof impu ities from that layer.

Another feature resides in apparatus for in'- U timatelyf mixing upper and-lower layers from the'layer is passed to a preceding pcintand used as the solvent forthe preceding extraction.

Another feature of the invention resides in the provision of an improved apparatusin which a plurality of solvents for respective constituents of the oil fiow in counter-current relation, or in other words. so that paraffinic solvent is introduced adjacent the end of the apparatus where the naphthenic oil is removed and so that the the end where the parafilnic oil ,is removed. Preferably the' apparatus is so constructed that the oil is introduced into an extracting chamber intermediate the ends of. the system and is separated into fractions which are advanced towards opposite 'ends of the system,.while the solvents fiow from the ends 'of the apparatus in countercurrent relation. v

In one specific form of apparatus in accordance with the invention the solvents fiow through a tower, the parafilnic solvent rising and dissolving parafilnics to form an upper layer and the naphthenic solvent settling and dissolving naphthenics-to form a lower layer, the countercurrent fiow taking place while the constituents are actually in contact with one another;

In another form of countercurrent method and apparatus in accordance with the invention. .a lower layer from a succeeding chamber and an upper layer from a precedingwchamber, containing respective solvents, are intimately intermingled and then fed into a generally horizontal settling chamber, near one end. and permitted to gradually settle out toward the other end of the chamber and form therein an upper and a lower layer. Particular advantages are secured with this type of apparatus as will be hereinafter pointed out. v

A relatively specific feature of the invention resides in apparatus for carrying out the extraction continuously in a series of separate chambers, although it will be understood either a single chamber of considerable length or discontinuous batch type apparatus may be employed within the broad principles of the invention.

Another feature of the invention resides in apparatus which accomplishes the treatment of both layers simultaneously in a closed system, the solvents being recovered and recirculated.

Other objects, featin'es and advantages of the invention will appear from the detailed description of the several illustrative embodiments described, although it will be understood that the invention in its broader aspects is not limited'to such embodiments. I I In the drawingsin which like reference'characters indicate similar parts.

11g. 1 shows diagrammatically apparatusembodying .my' invention and whereby my process perature' c'ontrolling and solvent recovery fea"-- 'Pig. 2 shows diagrammatically a modification of apparatus whereby counterfiow of solventsxand extraction of parafilnic and naphthenicfractions may be practiced, such apparatus including temare effected, the apparatus shown in tmfi il'sure Jbeing adaptable to the solvent recovery muted,- perature controlling features shown in Fig. 3 shows diagrammatically apparatu's'fenfi I bodying my invention and whereby my mayxbe practiced as a batch operation continuous features;

Fig. 4 is a diagrammatic view of another of apparatus in accordance with the invention.

In the .practice of this invention, oil which is to be divided into fractions which are respectively more parafilnic and more naphthenlc than the original oil is treated or extracted with a solvent having greater solvent power for naphthenic constituents than for parafiinic constituents, while the oil is in thepresence of a solvent which has" greater solvent power for parafiinic than for naphthenic constituents. Usually the latter solvent comprises one or more hydrocarbons of the parafiin series, and it reduces the viscosityof the more parafiinic fraction and facilitatu a. more rapid and complete separation therefrom b t-gravity of a solution of naphthenic constituents. Also, it is thought that'theadvantagesof' this invention are due in part to a replacement by the parafiinic solvent, which is'a parafiin of such parafilnicconstituents of the oil as may be dissolved in the naphthenic solvent, the parafiinic solvent being readily recoverable from the'more' naphthenic fraction, and thus facilitating more.

complete recovery of the parafiinic constituents of the oil in and 'a's'the more paramnic fraction thereof. In the description herein of apparatus embodying my invention, and whereby my process may be practiced. all of. the above-mentioned are present, but it is to be understood that the separate use of the described features falls within the scope of this invention-although such feafeatures of this invention and additional features tures co-operate when used together to produce the advantages of this invention.

Referring to Fig. 1, a counterfiow of paramnic solvent and naphthenic solvent is maintained through contacting or extracting elements II and Ii and the oil to be separated into fractions is introduced to the counterfiowing solvents at an intermediate point Theoperation will be described in connection with the use of nitro-benzene having sulphur-dioxide absorbed therein as the naphthenic solvent and propane asthe parafiinic solvent,.although it is to be understood that other suitable solvents may be employed. Nitro-ben'zene from tank II, which may be initialiyfilledby make-up inlet ll, is passed bypump ll through'plpe ll, pipe it, and cooler top of absorber 1., which may be of anyconstruction, causing contact of the liquid with gas il, which contains refrigerant coil ll, into-"the therein. Sulphur-dioxide from gas holder II. is

passed by pipe 2i through cooler 22- containing refrigerant coil 23, and pipe 24, to the bottom of V absorber it, from which the residual gas is vented by vent II or returned by pipe it and pump ll -7 pipe I5. By opening valve 30 and closing valve 5 3|, the sulphur-dioxide absorption apparatus and step may be eliminated. Then the naphthenic solvent passes through mixer 32, heat exchanger 33,-pipe 34, cooling coil 35, and pipe 36, into the upper portion of extractor I I.

Propane contained in tanks 31 and 38 ispassed by pumps 39 and 40 through pipe 4| to pipe 42; and propane in tank 43, which may be initially filled by make-up inlet 44, is passed by pump 45 through pipe 46 to pipe passes through heat exchanger 41, pipe 48, heat exchanger 49, pipe 50, cooling coil SI, and pipe 52, to the lower portion of extractor I0.

Oil to be separated into fractions is passed from tank 53, which may be supplied by makeup inlet 54, by means of pump 55, pipe 56, mixer 51, heat exchanger 58, pipe 59, cooling coil 50, and pipe 6|, to the upper portion of extractor I0.

Contacting and extracting towers I0 and II are provided with any type of'packing,62, such as 2 coke, bricks, or raschig rings, suitable for permitting contact of the oil and the solvents; and they are maintained completely filled with liquid. Pumps I4, 39, 40, 45, and 55 maintain such pressure within the extracting towers, and cooling coils 35, 5|, and 60 maintain liquids flowing to the towers I0 and II at such temperature that the liquids in the towers do not vaporize and are at such temperature that separation of a solution of more naphthenicfraction from a solution of more paramnic fraction occurs. From the bottom 01 extractor II there is drawn by pump 63 a quantity 0! the heavy fraction separating out in extractor II, and possibly a part of the lighter layer separating out in extractor I0, depending,

upon the rate of operation of pump 62. Liquid so withdrawn comprises naphthenic constituents, naphthenic solvent, paraflinic constituents, and paraflinic solvent, andit is passed through pipe 64, heat exchanger 58, and pipe 65, into pipe 55, and mixed in mixer 51 with the incoming oil to be separated. The oil tobe separated may contain wax and have a melting point between 85 F.

and 90 F. necessitating the use of a steam coil' 66 in tank 53 in order that-it may be in liquid form; butafter admixture with the liquid withdrawn from the extractor by pump 63, the incoming oil may be chilled in cooling coil 60 to a temperature well below that at which the wax therein solidifies, and then the wax solidifies in par- 55 ticles separate from each other and separate from the oil, leaving the oil free to be acted upon by the selective solvents in-extractors I0 and II.

At the temperature maintained within extractors I0 and II, the solvents have limited mutual solubility, and separation into an upper layer comprising the more parafinic fraction dissolved in the paraflinic solvent and containing some naphthenic solvent, and a lower layer comprising the more naphthenic fraction dissolved in 5 naphthenic solvent and containing some parafflnic solvent, readily occurs. The resulting upper layer passes from the top of extractor II through pressure regulating valve 61 to evaporating tank 68 containing cooling coils 35, 5| and 60. The

-, pressure in tank 68, and therefore the temperature therein, is regulated by withdrawing therefrom vapor of parafiinic solvent by compressor 69, the output of the compressor passing through condenser 10 into tank 43.

The more parafiinic fraction, partly freed of 42. Propane in pipe 42 tractor In vaporizer I00, the heat of coil sulphur-dioxide, which passes by pipe II2 to paraifinic solvent, is passed from-tank 68 by pump H to separator 12. Naphthenic constituents dissolved in naphthenic solvent and collecting in 1 the bottom of separator 12 pass through heat exchanger 33, in which the temperature thereof is raised',.- and then they pass through pipe 13 into pipe- I5 and are mixed with incoming naphthenic solvent in mixer 32. occurs because the temperature and concentration of parafiinic solvent therein are both lower than in the top of tower II. Thus, naphthenic constituents which are undesirable'ingredients, of

the more parafilnic fraction are eliminated there-' from; and the oil added to the incoming naphthenic solvent in pipe I5 permits the reduction of the temperature thereto in cooling coil 35 to a temperature which may be below the crystallization point-of the naphthenic solvent without occurrence of such solidification or crystallization.

The upper layer in separator 12, comprising the more parafiinic fraction and solvents, passes through pipe 14, heat exchanger 41, vaporizer I5,

pipe 16, vaporizer 11, p'pe 18, pipe 16, vaporizer 19, pump 80, and pipe 8|, to parafiinic run-down tank 82, from which it may be withdrawn by pipe 83. In heat exchanger 41, parafiinic solvent is cooled, In vaporizer 15, the heat supplied by coil 84 vaporizes paraflinic solvent, which passes by pipe 85 to liquefying condenser 86, from which liquid paraflinic solvent passes to tank 38. In vaporizer 11, heat supplied by coil 89 drives oil The separation in tank 12 sulphur-dioxide gas, which passesby pipe 92 to gas holder 20. In vaporizer 19, heat supplied by coil 94 vaporizes naphthenic solvent, which.

passes through condenser 95 to tank I2.

Tar collecting in the bottom-of extractor I0 and constituting the more naphthenic fraction dissolved in naphthenic solvent and containing some paraflinicsolvent, is withdrawn from ex- I0 by pump 96 and passed through pipe 91, heat exchanger 49, vaporizer 98, ppe 99, vaporizer I00, pipe I'0I, pipe 99, vaporizer I02, pump I03, and pipe I04, to naphthenic run-down tank I05, from which naphthenic oil or tar may be withdrawn through pipe I05. In heat exchanger 49, paraflinic solvent is cooled preparatory to further cooling in coil 5I, and the extent of cooling of paraflinic solvent may be regulated by adjustment of valve I01 in pipe 50 and by-pass valve I08. In vaporizer 99, the heat of coil I09 vaporizes parafiinic solvent, which passes to liquefying condenser H0 and then to tank 31. III drives off pipe 92.

If sulphur-dioxide or an equivalent ingredient is not employed, Vaporizers 11 and I00 are eliminated by opening valves II4. In vaporizer I02, the heat of coil II5 vaporizes naphthenic solvent, which passes to condenser II6 and then to tank I2.' Pumps 11 and 96 provide the pressure necessary for condensing parafiinic solvent in condensers 86 and H0, and

the pressure on the fractions freed of propane" is released by valves I I1, and vacuum pump H0 insures that naphthenic solvent will be vaporized in Vaporizers 19 and I02 at a temperature which will not alter the same or the oil incontact therewith.

In the extraction step in towers I0 and II, the continuous upward flow of paraiiinic solvent and the continuous downward flow of naphthenic solvent, preferably at temperature at which the mutual solubility of those solvents is limited, carries upward paraflinic constituents of the oil and H3 and closing valves A apparatus naphthenic fraction carries downward naphthenic constituents of the oil. Just prior to flow of paraflinic constituen'ts from the extracting step they are washed with naphthenic solvent, and just prior to flow of naphthenic constituents fromthe extracting washed with -p'araflinic solvent,

stituents of the oil which are solution of naphthenic constituents. Apparently parafllnic solvent entering by pipe 52 takes up naphthenic solvent which is released near the top of the extracting towers because of the lower temperature there; and the released naphthenic solvent moves downward and takes up oil constituents, thus giving a circulation within the extracting towers which aids the freshly supplied naphthenic solvent.

In Fig. 2, there is shown a modiflediorm of apparatus whereby the counterflow of solvents f and contacting thereof with oil is effected, this being more suitable in the case of solvents having a smaller diflerence of specific gravity than nitro-benzene and propane. Through the contacting or extracting tanks I25, I2I, I22, I22, I24 and vents is maintained, and oil to be separated is introduced to such counterflow at an intermediate point thereof. Naphthenic solvent from tank I2 is passed by pump I4, pipe I25, mixer I21, heat exchanger I25, cooler I25, and mixer I24 of tank I25,'and then into that tank. From the bottom of tanks I25, I24, I22, I22 and I2l, naphthenic solvent passes by pipe I2I, pump I22, pipe I22, and mixer I24, intothe next preceding tank. The steam supplied'each pump I22 is regulated by' a valve I25 controlled by a float I25, which floats upon a solution of naphthenic constituents but sinks in a solution of paraflinic-constituents. From the bottom of the first tank I25, the more dissolved in naphthenic solvent and containing some paraiiinic solvent is withdrawn bylpump 252 to tank I25, from which it may be withdrawn for recovery of solvents by pipe, I21. The steam supply to pump 252 is controlled similarly to the steam supply to pumps I22.

Paraiilnic solvent from tank pump 45 to mixer I24 of the 42 is passed by first tank I25.

Parafilnic solvent containing parafllnic oil con- -I4I, cooler I42, and mixer.

. recovery by means of pipe the top 0! each tank to the mixer I24 of the next succeeding tank by means of pipe I25. In passing from tank I24 to tank I25, the upper layer from tank I24 through heat exchanger I25 and then into pipe I25 and is mixed in mixer I2'I with naphthenic solvent, and the mixture through heat exchanger I25, cooler I25, and mixer I24 of tank I25, and then into tank I25.

stituents passes from Oil to be separated passes from tank 52 throiiEh I45,- heat exchanger pump 55 and pipe 55 to mixer I24 into tank I22: and the upper layer of tank I2I, in passing to the tank I22, passes through heat exchanger MI and is mixed in mixer separated, and the oil tank I22 with the upper layer of the lower layer of tank I22.

The more paraihnic fraction in solution in parafllnic solvent and containing some naphthenic solvent passes from the top of tank I25 through pressiue-controlled valve I42 to tank I44, from which it may be withdrawn iorsolvent to be separated enters tank I2I and of pressure-controlled valve I42, liquefied solvents may-be employed; and the evaporation of cooler I25 ratus shown in the construction that upper fore it is passed from the system.

I25, a counteriiow of 501- introduction of oil to I40 wlththe (ill to be I45. By adjustment solvents in tanks I25 and I44, oreither of the may provide refrigeration for cooling coil I45 in and cooling coil I41 in'cooler I42.

-In operation, the relative rates the rate of the respective supply pumps thereoi! that the level of the dividing line between the upper and lower layers in contacting and separatin'g tanks I25 to I25 may be properly maintained by pumps I22 and pump 252. I

The solvent recovery and temperature regulating features of the apparatus shown in Fig. 2 may be employed in connection with the appa- Fig. 1 for those purposes- It will be apparent that from the operation of shown in Fig. 2 the flow of the upper layer in eachtank toward the right causes layer to take up more and more paraiiinic-constituents oi the oil, and that it is thoroughly washed with naphthenic solventbe- It, will also be apparent that the lower layer in being passed through the several tanks toward the left in the of supply of oil 7 and solvents will be so regulated by controlling system. Such thorough washing prior to removal from the system displaces undesirably absorbed constituents; and the presence 0! added paraflin hydrocarbon increases the proportion of parafllns present and assists the iinal separation. As a' result, proper separation is obtained in the treatment of highly naphthenic oils in connection with which separation could not be obtained by the mere use of nitro-benzene alone, at least without the use oi benzene. In the construction'shown in Fig. 3, contacting, extracting, and separation are effected in tank I55, which is provided with means for the be separated, naphthenic solvent, parailinic solvent, and certain naphthenic layers resulting from intermediate separating steps, as hereinafter described. Tank I55 is provided with means for eifecting circulation and agitation of the contents thereof, including pipe Oil may be supplied to tank I55 from tank 52 by pump 55, which discharges the oil through valve I52 into pipe I51.

A heavier layer comprising more naphthenic constituents, naphthenic solvent, and some paramnic solvent may be passed from tank I55 to evaporator I52 by closing valve I55, opening valve I52, and operating pump I52 to pass that layer through valve I54, pipe I55, valve I55, and pipe I51. Volatile paraiiinic solvent'is removed-from the contents of tank I52 by passing through pipe I55, cooler I55, pipe I15, valve Ill, and pipe I12, to tank I12, in which paramnic solvent is collected and which may be initially supplied through pipe I14. Valve I1I controls the release of pressure upon the contents of evaporator I52. By opening valve I15, liquid solvent may be passedthrough pipe I15 on to bubble decks I11 in evaporator I52 to assist in the separationoi the solvent vapors an excesdve amount of nitro I5I containing valve I52, pump I52,pipe I54, 7

I55, to which from the liquids. When removal of parafllnic solvent is completed, pressure on the evaporator is reduced to permit vaporization of the naphthenic solvent at a temperature low'enough to avoid alteration of either the oil or the solvent. To this end, valve "I is closed and valve I16 is gradually opened in pipe I19 leading to tank I60, in which naphthenic solvent is accumulated and which may be initially filled by pipe I6I. During 10 the evaporation of naphthenic solvent in tank I63, the contents thereof is heated by circulation through heater I02 by means of pump I64, liquid being withdrawn from tank I63 by pipe I65 and returned thereto by pipe I66; and reduced pressure is maintained in tank I63 by means of compressor I61 connected to tank I00 by pipe I66 and discharging by pipe I69 through cooler I90 into separator I9I, from which naphthenic solvent flows by pipe I92 containing valve I93 back to tank I60, and non-condensable vapors pass by pipe I94 to compressor I95, which discharges into pipe I 6I Upper layers containing .the more parafilnic fraction dissolved in paraflinic solvent and con-' taining naphthenic solvent, which are formed and separated in tank I50, may be passed to evaporator I96 by closing valve I66 and passing the layer through pipe. I65, valve I91. andpipe I96. Volatile solvent is recovered from the contents of evaporator I 96 by passing through pipe I99, cooler 200, and pipe 20I, valve 202, and pipe 203, to paraillnic solvent tank I13, the evaporation being controlled by valve 202. As in evaporator I63, separation of liquid from vaporsis assisted by reflux liquid passed through valve I15 and pipe I16 to bubble decks I11. After completion of the separation of volatile solvent from the contents of evaporator I 96, valve 202 is closed, and the pressure in evaporator I96 is reduced by opening valve 204 in pipe 20I, which leads to naphthenic solvent tank I60, in which reduced pressure is maintained as above described. The volatile solvent under high pressure in pipe I6I passes through cooler 205 and pipe 206 to volatile solvent tank I13. 7

Non-condensable gases in tank I13 may be vented by means of pipe 201 containing valve 206. Paramnic solvent may be introduced into tank I50 through pipe 209, valve 2I0, pipe 2, valve 2I2, pump I53, and pipes I54, I55, and I51, valve I52 being closed and valve I56 being open. Similarly, naphthenic solvent may be introduced to tank I50 by l ising that solvent from tank I60 through pipe 2J3 and valve 2I4 to pipe 2I I.

The more naphthenic fraction, freed of solvents, is w'ithdrawn from evaporator I63 through pipe 2I5 by pump 2I6 and passed to tank I05.

The more paraflinic fraction, freed of solvents, is withdrawn from evaporator I96 through pipe 2" by pump 2I6 and passed to tank 62.

The coolers or condensers, I69, I90, 200, and 205, are cooled by water coils 2I9.

In order to obtain the beneficial effects of counterflow of solvents during the treatment of successive batches of oil to be separated, in the apparatus shown in Fig. 3, partially treated or extracted heavier layers produced in tank I50 in successive operations are held in a plurality of tanks, which may vary in number, but of which four are shown in Fig. 3, namely, tanks 220, 22I, 222, and 223, the contents of these tanks being held at the pressure existing in tank I13 by means of pipe 224 leading from pipe 201 7 and connected to each of said tanks by a valve and the naphthenic 22I while the paraflinic layer is retained in tank naphthenic layers As the result of the treatment of successive batches of oil from tank .53, tank 223 will contain a heavy layer least rich in naphthenic constituents, tank 222 will contain a layer richer in naphthenic, constituents, tank 22I will .contain a layer still richer in naphthenic constituents, and

tank 220 will contain thenic constituents.

Assuming that a lighter or paraflinic layer a layer very rich in naphformed in tank I50 after discontinuance of the circulation of the contents of that tank has been transferred to evaporator I96 for the removal of solvents, as above described, then the contents of tank 220 will be transferred to tank I50, and there will also be transferred to that tankfrom tank I13 the amount of parafiinic solvent necessary for the treatment of a new batch of oil to be separated. Then the contents of tank I50 is circulated by pump I53, as described,'and the necessary cooling of the circulating liquid is accomplished by adjustment of valve I59 and operationof compressor I60, as above described. Circulation is discontinued after sufilcient contacting of the ingredients of the mixture has occurred, and there forms in tank I50 a heavy naphthenic layer and a lighter parafiinic layer. The heavier layer is transferred to evaporator I63 for removal of solvents, as above described; and the parafllnic layer is retained in tank I50. Then the naphthenic contents-of tank 22I is transferred to tank I50 and circulated by pump I53, and during such circulation there is added to the contents of tank I50 by pump 'a-batch of oil to be separated. drawn from tank 53. Circulation is continued until the added oil is put into solution in the naphthenic and parafiinio solvents'in tank I50; and upon cessation ofcirculation, two., lay e rs form and the naphthenic layer is transferred to tank 220 and the paraflinic layer is retained in tank I50. It is. to be understood that cooling is maintained during each circulation, in the manner described.

Then the naphthenic contents of tank 222 is transferred to tank I50, and the contents of tank I50 is again circulated and separated into layers, layer is transferred to tank I50. Then the contents of tank 223 is similarly treated, the resultant naphthenic layer being transferred to tank 222.

Then, the amount of naphthenic solvent necessary for the treatment of a batch of oil to be separated is transferred from tank I to tank I50, and the resulting mixture is circulated and the resulting naphthenic layer is transferred to tank 223. During these operations there has been completed in evaporator I96 the removal,

of solvents from the more parafllnic fraction produced in the preceding cycle of operations, and the solvent-freed more parafllnic fraction so produced is passed to tank 62. Accordingly, the parafiinic layer remaining in tank I50 after the transfer of the naphthenic layer therefrom to chamber 246 is withdrawn from near the bottom of this chamber through valve 262 and pipe-263,

2,088,611 proper or desired rate of flow. The flow oi'upper 7 It will be understood that the number of chambers may be varied, or that a layer may be passed into a chamber further along than the one next to the chamber from which thelayer is withdrawn: Y

The upper or paraiilnic layer. from end chamber '25l is withdrawnthrough valve 260 and pipe Ni and treated as hereafter described for .removal of solvents, while the lower layer from and treated for removal of solvents.

The present apparatus is particularly adapted for handling a normally gaseous solvent, suchas propane, and maintaining it in a liquid state without the need for refrigerationor for the conduct of operations at temperatures at which wax in the oil'would precipitate. The apparatus provides for maintaining the materials in each of the chambers 243-25| under adequate pressure, for instance, by pumping the oil and solvents into the system under pressure and limiting the withdrawal of the paraflinic and naphthenic .layers to such a rate as to maintain the desired pressure, which may vary considerably depending onthe solvent employed: 160 pounds per square inch is satisfactory for propane. In order to prevent vaporization of solvent in chamber 25!, the valve 260 is preferably of any known back pressure type, arranged so that the desired pressure is maintained in chamber 25| regardless; of the pressure in line (26L Extraction chambers 243-25i and the connecting pipes for circulating liquid are all maintained full of liquid, so that there will not be air spaces inwhich a solvent may volatilize to bring about an ineflicient .operation or the need for unduly large apparatus.

At the same time, it has been found desirable to circulate liquids in the chambers near the center of the apparatus, particularly chambers 243, 244 and 241, at a considerably higher rate than the rate at which the final layers are withdrawn from, the end chambers. That is to say, where a relatively pure solvent, to constituents present in relatively small proportions in the liquid in an end'chainber, is contacted with such liquid, the constituents are readily stripped from the mixture by the solvent liquid back into the same which is hungry for them. On the other hand,

where the oil is initially treated with solvents.

already containing substantial amounts of dissolved constituents, the circulation of the liquids is advantageously much greater in order to provide a more intimate contact between all portions of the liquids. Preferably, an equilibrium is established between the solvents and dissolved constituents in each chamber, the recirculation aiding in accomplishing this.

The present apparatus provides for maintaining the desired circulation at various points, by employing a pump 25! for each of the extraction chambers from which a lower layer is withdrawn,

and by providing a valve 259 for controlling the rate of flow of each pump. It has been found that advantageous results are secured where the liquid from the bottom of chamber 243 is pumped into the chamber 244 at a rate two to four times as fast as the rate at which layers are withdrawn from the ends of the apparatus, although the invention in its broader aspects is not restricted to any particular rate of recirculation. If desired, it is possible to by-pass a portion of the chamber from which it was withdrawn in order to aid in maintaining the which is partial with fresh naphthenic solvent.

solvent removed from each treatment and con-. taining some non-lubricant constituents is preflayer from each chamber is thus controlled by therate at which pumps 25'! circulate fluids from. the bottom of the chambers, so that by adjusting the flow of thelower layers the flow of upper layers is automatically controlled. The present apparatus is thus capable of establishing condi-.

tions of equilibrium in eachof the given chambers so that with a given grade of oil the conditionsof treatment and quality of the product may be maintained substantially uniform.

The temperature may be around 60 F. in the chamber 243 and possibly slightly higher in the end chambers Lowering the temperature in the end chambers may increase the recirculation slightly. It has been found advantageous to keep the temperatures throughout at such a degree as to' promote the immiscibility of the solvents, and coolers or heaters may be provided if necessary for maintainingthe proper, determinable conditions for given solvents.

The present apparatus is particularly simple to construct and efficient to operate where a countercurrent flow of large volumes of liquid is required, and where the solvents are several times the amount of oil under er'ally desirable. At the same time, the provisions for intimate mixing and subsequent settling in a generally horizontal concurrent flow in the individual chambers appears to produce a superior and more rapid separation of the oil into-fractions distributed in the respective solvents. Es

treatment, as is genpecial advantages are secured by the construction of the apparatus in such manner that each 4 successive upper chamber 243 to layer from the initial layer in the final layer in chamber 25l grows richer in paraflinic pcrtions of the oil, while Similarly, the lower layer passing from chamber,

243 to the preceding chamber 246 is counterflowed with respect to solvent for the paramnic or lubricating oil constituents, so that the practically fresh solvent in chamber 246 has to strip but relatively small amounts of paraiflnlc oil from materials from which most of the paraflinic oil has alreadybeen removed.

Excellent results may be secured by separating from the oil a parafiinic layer which may contain some other constituents ofthe oil, treating the lower with a fluid including a naphthenic solvent, removing the solution thus formed from the paraflinic layer, repeating the solvent treatment and removal to produce successively a more pure layer, and ultimately washing the parafllnic oil The naphthenic erably employed as the fluid for the next preceding treatment, where it will dissolve more of said constituents. It will thus be appreciated that as the parafilnic oil contains less impurities the solvent for impurities is stronger in each succeeding step. At the same time, it will be appreciated that the paraflinic oil is dissolved in a paraflinic solvent which in each stage acts to dissolve parafiinic oil carried over by the naphthenic solvent from another stage. There is thus a countercurrent flow in the sense that the less the other constituents mixed with the more concentrated is the naphthenic solvent; there is also a countercurrent flow in the sense g combustion en ines.

' c solvent and naphthenic solvent 7 flow in opposite directions to one another.

on the other hand, there is se from the stock alayer relatively rich in non-lubricant sconstituents and also containing some lubricants, which layer is treated with parafllnic solvent in a system operating upon the principles set forth in connection with the treatment or the para!- flnic traction. A

The separation may be promoted by adding waterto the crude oil in .the apparatus to reduce the solubility oi the upper layer in the lower lay , Apparatus or the following character may ad- 7 l vantageously be employed ior recovering the solvents from the extracted oil fractions.

The parafllnic oil, c solvent and some entrapped naphthenic solvent discharged irom chamber "I and passing valve 2" is carried by line "I .to a suitable evaporator ill in which only the paraflinic solvent is vaporized by heating the mixture to a suitable temperature, say 350 1''. where the solvent is propane. The vapor is carried by pipe ill to condenser 21!, where and the liquefied solvent is passed nk will. The liquid paraflinic a rate controlled by a valve ill operatlvely connected 'to a float!" in the evaporator, and is cooled in cooler I'll to a suitable temperature, say 'l40 It, where cresylic acid is employed as naphthenic solvent.- Upon passing the cooled mixture into a receiver Ill, a substantial portion oi the naphthenic solvent forms a lower layer, in which some small be carried, while the balance of the naph thenic solvent c oil and the form anupp r be separated from the mist and may be drawn oil .trom the bottom of the receiver Ill and passed into line I by-steam pump 21!, controlled by valve will and float Ill, connected in any convenient manner so that the operation of the pump iscontrolled by the level 01' naphthenic solvent in the receiver 21}.

' The upper layer irom receiver ill may be passed through line 202 into an evaporator "I in which the liquid may be heated by high presout of direct contact with the liquid,

5 cs by means or a iractionating tower having a lower flash evaporator portion in which the lighter fractions 0! the materials are vaporized, and an upperstripping deck portion, in which the non-paraflinic vapors are condensed. the heat of condensation being employed-to aid in heating the mixture entering the flash section. Suitable arrangements may be employed (or heat exchange between relatively hot and relatively cool materials atdesired points. in the solvent recovery system. The naphthenic solvent vapors' may be liquefied in condenser I and passed to storage tank I" through line I". The parafllnic oil irom the evaporator or'still It! may be passed through line 201 by steam pump 2 controlled by valve "I and float ill, and into tank I"; g

Thls'oil constitutes a highly superior lubricating oil which may be employed, after dewaxing if it has not previously been dewaxed, for internal without further treatment,

, able to subject pass into tank naphthenic oil irom the bottom or evaporator 8.!

layer. In this manner, a portion of the naphthenic solvent may I a .but substantiallwall o! the oil constituentsiwhlch In some, specialcases. however. it, may be ,desirthe oilto other treatment, for instance, for removing speciiic impurities, which I may' occur in certain crudes.. Such additional treatment, 1! desirable for any reason, will be is minimised where lubricating is produced in accordance with the present invention.

The naphthenic oil, naphthenic solvent, and some c solvent leaving chamber 2 under the control otvalve "Lpassee through line I" into an evaporator seam which'par ailinic solvent is volatilised; The 30!- vent-vapors pass through line iii intoa condenser III, where they are liquefied, and then ill. The naphthenic solvent and maybe assed throughline I" into an evaporator IN. A valve "I controlled in any convenient manner by a float It. serves to regulate the newer naphthenic solvent and oil from the bottom of evaporatortll.

In the evaporator l, which'iunctions-similarly tothe evaporator I, the naphthenic solvent is driven oi! from the mixture and is condensed in condenser 1 and then passed through line Ills into storage tank I, where it mingles with the naphthenic solvent removed from the 0 oil. The naphthenic oil or tar from the bottom oi the evaporator I is conveyed by line I and pump 8 into storage tank Ill Thepumplll maybeasteampumpsimilarto-. pump 2 and may be similarly controlled by a valve Iii operativelyvconnected to float Ill.

A high yield of naphthenic oil, which may be more or less tarry, depending upon the crude treated, is thus recovered and is useiul for many In order to return the the receiver 213 into the solvent may be pumped into line 252, and-this steam pump may be controlled by a constant flow controller lit, in order to supply the paraflinic solvent to the extraction desirparaflinic solvent from extraction system. the by a steam pump lit 46 tinuous operation in the apparatus 0! Fig. 4. 'I'heconstant flow controller may be of any known construction. In order to make upior solvent losses, additional solvent may be led into receiver 213 irom any'suitable source of supply (not shown) f The naphthenic solvent from the receiver 2 is pumped by steam pump!!! into the line I where it mingles with a naphthenic solvent from the receiver 210. The pump III is, controlled by a constant flow controller "I connected so that it regulates the total flow oi naphthenic solvent into the chamber 2. Additional naphthenic solvent may be supplied to' receiver 2" as required, from a source of supply (not shown).

The present apparatus nts a number of advantages, among which is its simplicity of construction. Moreover, the construction is such that an eflicient and intimate mixture oi the oil constituents and solvents is eilective, while 'at the same time a rapid and eihcient separation of the liquids into layers is accomplished. Thus, a sharp separation is achieved between the constituents which are desired in the lubricating oil traction, and the other constituents, so that not only is a high yield of lubricating oil procured,

are desirable in the lubricants are found in the lubricating oil fraction which, on the other hand, is substantially free of undesirable constituents I.

where the oil is to be used for'lubricating an automobile engine. At the same time, the apparatus is reasonably inexpensive to build.

Where the terms parafllnic solvent and naphthenic solvent are employed herein, they refer to thesolvent action rather than to the chemical constitution of the fluids employed as solvents. Moreover, while it is believed thatthe action of such fluids is really one of dissolving oil constituents, the invention is not to be restricted to this theory of operation, for, it may be that the fluids simply carry along the oil constituents by some action which may not be at present entirely understood. Accordingly, the term solvents is employed with this thought in mind.

Where the term lubricating oil is employed it refers primarily to a fraction suitable for use in internal combustion engines, although the term is not intended to exclude oils with shades of difference in their properties. Moreover, the other constituents removed from; certain stock may possess lubricating properties for certain purposes, but these constituents are, nevertheless, referred to herein at certain points as non-lubricant constituents because they are much less desirable for the former purposes.

It will beunderstood that wax may be removed from the products of the present process, either before commencement of the process, or at some suitable point after the extraction and before or after the removal of solvents from the extracted oil fractions.

In the practice of this invention, the oils treated'will preferably be viscous oils, i. e., oils having a Saybolt universal viscosity of upwards of 50 seconds at F., including distillates and residues and mixtures thereof. By treatment in accordance with this invention, oils having characteristics comparable to or better than the characteristics of similar oils produced from Pennsylvania crude petroleum may be readily produced from oils from almost any field, including particularly Mid-Continent and coastal fields, it being animportant feature of this invention that oils having such desirable characteristics can be produced from oils having a high content of asphalt, in some cases so high that treatment thereof with a single solvent is impracticable.

In the production of oils in accordance with this invention, preliminary acid treatment is not necessary, although such a step may be performed; and the acid treatment ultimately required is markedly milder and more economical than acid treatment required to attain the same degree of purification without treatment in accordance withthis invention. For example, 011 treated in accordance with this invention may be brought to desired color bythe use of five to ten pounds of 98% sulphuric acid and five per cent of palm clay;' whereas the attainment of the same degree of purity without treatment in accordance with this invention requires as much as fifty pounds of suchacid, and also a heavy treatment of clay, per barrel of oil.

Oils constituting the more paraflinic fraction obtained by the practice of this invention are dewaxable by known methods to produce oil of any commercially desirable A. S. T. M. pour test, the type of wax-removal employed, 1. e., filter. pressingor bydiflerenceof specific gravity, beingso chosen as to be well suited to removal of the wax precipitated by chilling. Moreover, -when the solvents employed in the treatment of oil in accordance with this invention include sulphur dioxide, the upper layer of the separation, con

taining oil,. naphthenic solvent, and paramnic solvent, is well adapted to dewaxing processes, the sulphur dioxide acting to limit the wax remaining in solution after chilling and acting to prevent crystallization of the naphthenic solvent, relatively mild chilling to obtain oil of 0 F. pour test.

The solvents employed are preferably so chosen that their boiling ranges do not overlap each other or overlap the boiling range of the oil treated. Thus, a mixture of oil to be treated and parafiinic solvent is not to be confused with crude oil containing both naphtha and lubricating oil and comprising constituents of gradually increasing boiling point. Preferably, the solvents are separable from one another and from the oil by distillation. In the practice of is a feature that the solvent having greater solvent power for naphthenic than for parafllnic constituen of the oil is employed in conjunction with another solvent for the oil which preferably has limited solvent power for the naphthenic solvent. Thus, while preferred paraflinic solvents have been identified heretofore, there may also be used in conjunction with the naphthenic solvent a solvent which has a higher final boiling point than the solvents mentioned or is less parafflnic in composition or is not wholly composed of hydrocarbons or is not possessed of as marked selectively for solvents'above mentioned.

While the foregoing description makes reference to the liquefying or maintaining liquidity of solvents or the distillation or driving mi of solvents, by maintaining temperatures and pressures suitable to such conditions or effects, and such temperature and pressure conditions are readily ascertainabie by reference to handbooks or by-simple test, it is desirable to maintain in the contacting or extracting steps, and preferably throughout portions of the apparatus in which volatile solvents are transferred or used in liquid form, a pressure much higher than is necessary to maintain liquidity. For example, in the'contacting and extracting zones or elements of the apparatus pressures as high as 160 pounds may be maintained in connection with the use of propane. Thus, in the apparatus referred to in the drawings, successful operation has been efl'ected by maintaining the pressure in the neighborhood of 160 pounds in the contacting or extracting elements. In Fig. 1, such pressure may be maintained in towers l0 and H while tower I0 is at 75 F. and tower is at about 50 F., while the pressure in receiver 43 is about pounds, all pressures being gauge pressures unless otherwise specified. Wax-containing oil may be maintained at such "temperature as will insure complete fluidity thereof, e. g., 135 F. to F., prior to introduction into the system. .Subatmospheric pressure may be maintained, with or without simultaneous use of neutral substances acting to increase vapor pressure ofthe solvents, for the purpose of effecting the driving off or evaporation of solvents without decomposition of the solvents or of the oil; for example, evaporation of nitro- (10 F.) being required this invention, it

parafiine hydrocarbons as are the benzene may be effected by maintaining in tank I of more naphthenic fraction be effected. at a temperature conducive to layer formation at which the solvents have mutual limitedsolubility. In connection with the use of propane with nitrobenzene, an effective separation temperature is between 25 F. and 40 l t, for example, a temperature of 30 .1. may be maintained in separator II. when propane is used in conjunction with benzaldehyde, an efl'ective 0 separation temperature is F. when use with nitrobenzene containing absorbed sulphurdioxide. an effective separation temperature is 0 lit-10 F. When used with nitrotoluene, an effective separation temperature is F. when 15 using aniline with Pennsylvania gasoline having an end point of 300 F., separation may be effected-at temperatures as high as 150 1?. When usingfuriural with that gasoline, separation may be effected in the neighborhood of 80 When using pyridine with propane, F}. will effect separation. When using more volatile solvents than those mentioned, suitable pressures I 'and temperatures may diifer from the foregoing temperatures and pressures, but they are 25 readily ascertainable.

Procedure in accordance with this'invention produces a" fraction more paraflinic than the ori al; oil and'whichds an oil having more'desirable characteristi'csthan theoriginal oil, and a fraction which-is more naphthenic than the original oil and which contains the asphalt occurring in the original oil and is an asphalt having valuable commercial properties. The oil obtainedrepresents a substantially greater yield than the yield res'ulting friwm the mere use or a naphthenic solvent. and the oil possesses'equal or better characteristics than an oil produced by the mere use 'of a naphthenic solvent.

For the purpose of illustrating the effect and 40 results of procedure in accordance with 1 vention, various specific eramples are herein de scribed, with the understanding that this invention is not in any respect limited thereto but is amplified thereby. i p

Employing as the oil to be treated a stock compriisng a residue obtained from Santa Fe Springs California. crude oil and having the characteristics given below, that stock was sub-- jected to treatments as follows:

A. The stock was subjected to acid treatment in accordance with good refinery practice, using fifty pounds of 98% sulphuric acid per barrel of stock. and the resulting acid sludge (hereinafter referred to as asphaltum loss) was drawn off and the oil was treated with pound of palm clay per gallon by the so-called contact method. a

B. The stock. without acid treatment, was treatedin accordance with this invention with four pounds of propane per pound of stock and was separated into a more parafilnic fraction hereinafter referred to as the oil fraction and a more naphthenic fraction hereinafter referred to as asphalt and loss. The separation tem- 5 perature was 15F. under 120 pounds pressure. C. Thestockwas treatedwiththree pounds of nitrobenzene per pound of stock, but no separation was obtained'at any temperature down to 30 R, presumably Wokthe high asphalt content of the stock. a v f D. The stock was treated with 'one pound of nitrobenzene and two poundsof propane per pound of stock. the-separation of the solution) of more naphthenic fraction being eifectedat 76 1!, and the separation of the more paratilnic this infraction being efiected at 35 2!, under 60 pounds pressure.

E. The stock was treated with one pound of nitrobenzene and four pounds of propane per pound'of stock, the separation conditions being as described in test D". I

F. The stock was treated with'two pounds of nitrobenzene and four pounds of propane per pound of stock, the separation conditions being as stated in test D.

G. The stock was treated with two pounds of nitrobenzene and two pounds of propane per as in test D". a

In order to compare the effect of treatment in accordance with this invention with other treatment. in connection with a less asphaltic stock. tests were made with a stock of reduced asphaltic content consisting oi the oil resulting from test B, substantially freed of asphalt by propane treatment. as iollows:

H. The stock of reduced asphalt content was treated with one pound of nitrobenzene perpound of such stock, the separation temperature being 50 F. 7 v

J. The stock of reduced, asphalt content was treated with one pound of nitrobenzene and two pounds of propane per pound of such stock, the separation of the more paraiiinic fraction being eifected at 35 1''. and; the separation of the naphthenic fraction being eil'ected at 75 F.

K. The stock of reduced asphalt content was treated'with one pound of nitrobenzene and two pounds 'of petroleum ether per pound of such stock, the separation being effected at 50 F.

L. The stock of reduced asphalt content was treated with one pound of nitrobenzene saturated with sulphur-dioxide at 45 F. and two pounds of petroleum ether per pound oi su'ch'stock, the separation being effected at 0 F.

M. The stock of reduced asphaltlcontent was treated with two pounds of nitrobenzene and four pounds of propane per pound of such stock. the separation temperature being as stated in test .1.

An example of the treatment of an overhead distillate of Mid-Continent petroleum, said dis-- tillate having a specific gravity of- 225 A. P. 1., a flash point of 560 1''., a Saybolt universal viscosity of 153 seconds at 210 F. and 1125 seconds at F., a viscosity gravity constant of .838, and a viscosity index of 64,is as follows: i

N. The Mid-Continent distillate was treated with one pound of nitrobenzene and two pounds of Pennsylvania gasoline having an end point of 300 7., the separation being eifected at 50 F.

In connection with these tests, there is given below values which are the average of a number of values obtained by repetition of the tests, with respect to the stocktreated and the oil recovered;

as follows: 4

1. Percentage,

pound of stock, the separation conditions being 7 based uponthe stock treated. a

yield of oil, this being the oil obtainedby acid treating and clay treating or the more'paramnic fraction freed of solvent.

2. Percentage. based upon the stock. of loss of acid-treated oil or more naphthenic fraction freed of solvent.

- 3. A. P. I. gravity of the'resulting oil.

4. Saybolt universal viscosity at 130 F.

5. Saybolt universal viscosity at 210 1".

6. Flash point in degrees 1".

7. Fire test in degrees I".

8. Lovibond color, quarter inch cell.-

9. Conradson carbon.

10. Viscosity gravity constant. 11. Viscosity index. With respect to the asphalt or more naphthenic fraction, there are given below:- 5 12. Specific gravity. 8

13. Melting point. 14. Ductility. The average yields and characteristics of products obtained in tests A" to 6", employing 10 Santa Fe Springs residuum, and the characteristic of the charging stock, as-explained above, were as follows: I

15 Stock .4 B D E F G 1.100%.-- 30% 82.1% Notsiepa- 01.5% 70.5% 00.5% 55.8%

IS on 2. 01% 17.0% do. 38.5% 20.5% 33.5%4s.2% a. 10.8 25.4 21.0 0 20.3 25.1 20.7 28.4 4.143o- 207 505 .45.--- 282 257 232 200 20 5.158- 72 80 m 71 05 02 0. 445%--- 450 450 n 450 450 450 450 7. 505"- 510 510 do 510 510 510 510 8. B1110 Dark Dark -00.--. 50 5o 45 30 8113611 green 0. 0.0 0.7 do 0.30 0.40 0.30 0.38 10. .831 .801 do .827 .834 .824 .813 25 11.42 80 00 do .103 110 103 102 12. Notre- 1.074 "410---- 1.048 1.078 1.072 1.040

covered 13. -410.-- 150 do. 113 141 1:17 105 14. .415..- Brittle -do. 100+ 100+ 100+ 100+ 30 The average yields and characteristics of products having a flash test of 450 F. and a fire test of 510 F. obtained in tests H and J to N, employ-- ing oil of lower asphalt content, and the characteristics of the charging stocks, as explained above, were as follows:

Stock 11 1 x L M Stock N While the foregoing specific examples of charging stocks and final products relate -to- Santa Fe residue, to such residue treated with propane for 5 the removal of asphalt, and to a Mid-Continent distillate, it is to be understood that this invention relates to all oils having a viscosity upward of 50 seconds at 100 F. and containing both naphthenic and paraflinic constituents.

55 From the foregoing, it appears that by the practice of this invention products of highly desirable characteristics are obtainable from oils not separable by the use alone of a practicable proportion of a naphthenic solvent and that this 3 invention yields products having marked superiority over products obtained by use of naphthenic solvent alone. From the foregoing results, the effects of increasing and decreasingthe proportion of the solvents to the oil and to each other is indicated suillciently to enable the operator to achieve the desired results; and it is demonstrated that the use of a parafilnic solvent as herein described results in marked increase of yield and marked improvement of viscosity index.

7 In the practice of this invention, the proportions of solvents may be extensively varied and the above results indicate the'efl'ects of such variations and enable the operator to obtain whatever results he may desire, and commercial con- 75 ditions will impose some limitation upon those 8 heavy liquid fromone chamber to said first-named means,

proportions. Also, the operator may vary the duration of treatment and may repeat the treatliquid mixture, a series of successive chambers in which the lower layer removed from the firstnamed chamber is treated, and a series of successive chambers in which the upper layer removed from the first-named chamber is treated, and means to cause an upper layer to fiow from a chamber in the first-named series to a chamber in the second-named series.

2. In 011 refining apparatus, a chamber adapted to eflect a preliminary Stratification of a liquid mixture, 2. series of successive chambers in which the lower layer removed from the firstnamed chamber is treated, and a series of successive chambers in which the upper layer removed from the first-named chamber is treated, and means to cause an upper layer to flow from a chamber in the first-named series to a chamher in the second-named series and to cause a lower layer to flow from a chamber in the second-named series to a chamber in the flrstnamed series.

3. In oil refining. apparatus, means comprising a plurality of chambers adapted to cause intermediate chamber, means for withdrawing the relatively light solvent and materials dissolved therein from near the top of the secondnamed end chamber, means for withdrawingthe relatively heavy solvent and materials dissolved therein near the bottom of the first-named end chamber, and means for pumping the relatively another.

4. In oil refining apparatus, means adapted to cause contact between counterflowing liquids,

means near the bottom of said first-named means for admitting a relatively lightlsolvent thereto, means at a higher point for admitting a relatively heavy solvent, means at a point intermediate the point of admission of said counterflowing liquids for admitting oil means, means for withdrawing the relatively light solvent and materials dissolved therein near the top of said'first-named means, means for withdrawing the relatively heavy solvent and materials dissolved therein near the bottom of means for removing lighter solvent from the mixture withdrawn from near the top of the first-named means, meansfor cooling the remainder and separating heavy solvent therefrom, and means for returning the separated heavy solvent and any oil contained therein to the first-named means.

5. In oil refining apparatus of the character described, a series of chambers, means to introduce a aolventintooneend chamber, means to introduce a solvent into the other end chamber, means to introduce oil to be refined into an intermediate chamber, means to introduce material containing solvent withdrawn from each of said end chambers into said intermediate chamber, said intermediate chamber being constructed and arranged to enable the mixture to separate into layers, means to pump the lower layer from to first-named 12 4 said intermediate-chamber into a chamber be-. tween said intermediate chamber and an end chamber, means to causethe upper layer from said intermediate chamber to flow into a chamber between said intermediate chamber and the other end chamber by a diflerentiai pressure,

means whereby alower layer may be withdrawn from an end chamber and whereby an upper stantlaliy full of liquid;

layer may be withdrawn from the other end chamber at a combined rate substantially equal to the rateoi' feed of oil and solvents into the end chambers and intermediate chamber, wherebyallo'f said chambers may be maintained sub- 6. Method of separating oil into raflinate and .extract-!ractions by means of solvents, which.

comprises-admitting a solvent for rafilnate type oi constituents present in the oil into one end chamber of a series-o1 extraction chambers, admitting a solvent for extract type of constituents present in the oil intothe opposite end chamber, admitting the oil to be reflnedinto an intermediate chamber, passing mixtures containing said solvents into said intermediate chamber to cause the oil to separate intoraflinate and extract layers therein, passing the extract layer from said intermediate chamber into an adjacent chamber and toward the first-named end chamber, passing the rafllnate layer from said intermediate chamber into an. adjacent chamber substantiaily'higherrate 0! flow of oil and solvents between said intermediate chamber and said chambers thereadjacent, than the rate of withdrawal of rafllnate and extract iractions from the end chambers.

MA COLM H. TU'I'I'LE.

Images