US1664977A - Art of distilling lubricating oils - Google Patents

Description

April 3, 1928.

R. W. HANNA ART oF DISTILLING LUBRICATING OILS Filed 06%,.4, 1923 4 Sheets-Shea?l l gnvmxfo Gnome? lll Aprila, 192s.

4 SheetsSheet 2 Filed 001:.4, 1923 E Nw R W HANNA ART OF DISTILLING LUBRICATING OILS 4 Sheecs--Sheei'I 3 @N t" lill April 3, 1928.

y R. W. HANNA ART 0F DISTIVLLING LUBRICATING o'ILs Filed mp4, 1923 April 3, 1928.

R. w. HANNAf ART 0F DISTILLING LUBRICATING OILS Filed 0011.4, 1925 4 Sheets-5h66?l 4 gyn/sentez Patented Apr. 3, 1928. l

UNITED STATES PATENT OFFICE.

RICHARD W. HANNA,KOF PIEDMONT, CALIFORNIA, ASSIGNOR, BY MESNE ASSIGN- MENTS, TO STANDARD OIL COMPANY F CALIFORNIA, OF SAN FRANCISCO, CALI- FORNIA, .A CORPORATION 0F DELAWARE.

Amor DISTILLING LUBRICATING oI`Ls.U

Application inea october 4,

This invention relates to improvements in the art of distilling petroleum oils and has to do particularly with the distillation under vacuum of lubricating oils.

In the preparation of lubricating oils, difticulty is frequently encountered by the. formation of emulsions during the treatment of the lubricating oil distillates with acid and alkali.` These diliiculti'es include ineffectual Vneutralization of the organicacidity in the lubricating oils, a material loss in yield sutfcred through the removal or drawing oli of the emulsilied oil, a material drop in color during brightening operations, and a lack of color stability in the finished oil. These troubles are especially pronounced when the stock used to produce the lubricating oils is from an asphaltic or mixed-base crude.

Various causes have been ascribed for these emulsions;' chief of these are: The production of certain reaction compounds during the acid treatment, and the presence inthe oil of solids .in inely-divided state in suspension, or solids in colloidal form or state as distinguished from solidspresent in true solution. lVliileit is undoubtedly true that both of these causes are present, it' has been determined that a partial cause of the more-permanent emulsions encountered in the production of lubricating oils is due to the presence of certain tarry, heavy and asphaltic bodies, particles and constituy ents carried over with the vapors from the distilling equipment in the form of a inistV or spray. The carrying over of these tarry particles or .mist with the vapor is es. pecially lprevalent when the distillation is carried on under a reduced pressure.

Whenthese tarry bodies are carried over into the lubricating oil distillates, not only arev additional emulsion troubles encountered, but the acid treating yield is mate# Arally lowered, required color is more diiticult to obtain, andv greater skill on the part of the treating operators is required in order to produce an oil meeting the required standards. Furthermore, the resulting lubricating oils invariablygive a poor precipitation test.

In the distillation operation for the production of lubricating oil distillates, very materialadvantages are obtained' ivhen the entire composite or crude lubricating oil stock, comprising the light as well as the 1923. Serial No. 666,475.

heavy lubricating oil constituents, is fed into a single distilling unit operated continuously and at a uniformor constant temperature for the vaporization therefrom of all the ditt'erent lubricating oil constituents. When the distillation is thus conducted, so that the vapors from the higher-boiling-point oils are evolved simultaneously and-in a commingled state with the vapors of the xlower-boilingpoint. oils the temperature at which the higher-boiling-point oils can be vaporized is materially reduced. When such distillation is conducted continuously and at reatly re duced pressure and preferably with the use of steam, the temperature at vwhich the.

state?, there will be an increased tendency to q carryover with the evolved vapors a mist comprising the undesirable tarry particles before referred to.

It will also be apparent that when the advantages 0f the single continuous distillation operation under vacuum are employed and the vapors of the high-boiling-point oils and the l'ilovver-boiling-point oils are evolved simultaneously and in a commingled state, a subsequent separation of the evolved products intothe various desired grades of lubri cating o il fractions becomes necessary.

In order to thus employ the distillation advantages incident to evolving simultaneously and in a commingledk state, all the vapors ofthe various lubricating oil distillates and at the saine operation to obtain clean, well-fractionated and yse arate grades of lubricating oil fractions or distillates, free from the tarry constituents or mist which are' carried over in the vapors during the distilling operation, I extract from the commingled evolved vapors this mist before fractionation or condensation of the vapors.

Furthermore, through use of such mist extraction and tractional condensation, as employed in my invention. l am able to eliminate from the resulting lubricating oil distillates, substantially all of the light oils, such as gas oil, residual lamp oil and other light constituents which have remained in the crude lubricating oil stock from former topping operations and which, it permitted to remain in the lubricating oil fractions, would lower the flash-point ot the oils to such an extent thativhen the desired viscosity is reached in a given lubricating oil fraction the Hash-point would be too low to meet the required specifications and a rcrunning or reducing distillation operation will be necessary to eliminate such light and undesirable oils and bring the Hash-point up to requirements.

My invention thus makes possible the operation of a single continuous dist-illinp; unit under a reduced pressure less than atmospheric. and the simultaneous production ot a number of different grades ot lubricatingr oil distillates Without the necessity .tor condensing the evolved vapors in a eonnningled state and subsequently separat-ing the various stocks by fractional distillation. and also Without the necessity of reducing the separate tract-ions tor the required tlashpoint. in addition to having the required Hash-point corresponding to the viscosity of the respective distillates. these oils are tree from the tarry constituents or mist which promote emulsion troubles during subsequent chemical treatment. Due particularly to the extraction of the tarry constituents, particles or mist trom the commingled vapors before condensation, an increased treating yield and a better precipitation test are obdit "tained on the resulting oils than could be otherwise obtained. l

The invention in its severalaspects may be better understood and comprehended in connection with a description ot' a process comprising a preferred embodiment of the invention, and by reference to the accompanying drawings which illustrate apparatus in which may be performed such a process. The indicated apparatus is given for illustrative purposes only, and it is to be understood that thc arrangement shown and the details oit construction illustrated may be Widely varied Without departing from thescope ot my invention. Furthermore, the invention in its several separate aspects is ot the scope set forth in the appended claims and not necessarily limited in each of its re spective aspects to all of the steps detailedv in the description of a process comprising a preferred embodiment ot the invention.

lln the drawings: lin Fig. 1 l have indi- V:ated an apparatus by means of which a process embodying my invention may be peritormed. ln the apparatus as describedv in this gure, lt haveillustrated means tor pren mais?? -fore its introduction into the vaporizing still. Fig. 3 illustrates a form ot fractionating` condenser which may be employed. Fi 4 illustrates a rc-l'xeating 'tractional condenser which may be employed as a part ot' the apparatus. Fig. 5 is a sectional plan view ot the means employed for extracting the talrlfv particles or mist from the vapor; and Fig. 6 is a ltmgitiulinal vertical Isection thereof.

Referring to Fig. l:

i-represents a storage tank or source ot supply. 3 represents the feed-line ot the s vstem in which is a suitable pump 4. 'tor supplying the. oil to be distilled through the feed-line 3 under suitable pressure and by ivhich the desired velocity ot flou' is maintained. '.lhe feed-line 3 passes through a vapor heat exchanger 5, ot ordinary or any preferred construction. and thence passes through a residuum heat exchanger (i. ot' ordinary or any preferred construction. and thence through the heating coil 7. Thisl heating coil is mounted in a suitable furnace 8 and heated by suitable means. such as, for example. a burner-9. From this heat ing coil 7 the heated oil passes to a still or vaporizing` chamber 10. In line between the coil and the outlet into the vaporizing chamber 10, I intel-pose a. suitable pressure controlling valve l2, which may be set to maintain such pressure as may be desired or required. '.lhe form, shape or design ofthe still 'orevaporating chamber l() may be varied as desired, and its form or shape or construction forms no part of the` present invention. As shown, this stiller evaporator 10 is mounted over a suitable furnace l?) provided with heating means, such as a burner 14. iln p "actiec, the evaporator may be heat-insulated to prevent radiation losses` l5 represents the vapor outlet line which passes troni the evaporator 10 to the mist"` extractor 85. This mist extractor is preterably in drum torin and the interior chamber thereof is provided with a suitable number ot series oit' vertically arranged channels '86. These channels arc preferably formed surfaces @it 'the channel-irons causes 'a pre- Cpitationof the tarry constituents,particles or mist which are' Withdrawn from the mist extractor throughvthe oiitlet 87 and conducted by the pipe or conduit 88 back into the evaporating chamber or still 10, preferably at or near the bottom` thereof. From the outlet .side of the mist chamber .the vapor line 15 extends through the vapor yheat,eiiclianger 5 and thence to the inletchamber 3() of the reeheating fractional condenser31. From this'inlet chamber 30 the vapors pass through the tubes 32 into the outlet chamber 33 and thence by the pipe 34 to a second fractional condenser 3 5.'

.ber 39 are mounted a series of pans 40 preferably circular in cross-section and suitably mounted in the'fcondenser 31, as by suitable brackets or straps (not shown) welded to the inner shell of the condenser 31. Between adjoining pans 40 are interposed horizontal partitions 41 welded to the inner surface of the shell 31. These shells are proextractor i connections as shown in Fig. 2 may be readily connected to. and used in the apparatus indicated in Fig. 1, I have not deemed it necessary to vextend and show the same in` Fig. 1; 50, 51, 52 indicate respectivel the conduits or lines leading from thel ower portions of the condensing chambers of the condcnseis 37,35, 31, respectively. These respective conduit lines 50, 51, 52 are connected (as indicated in Fig. 2) through suitable cooling coils in coolers 46 and thence through suitable look-boxes 47 torcceiving drums 48 and thence to distillate storage tafnksor drums C, B, D, respectively. Each of the receiving drums is connected with the vacuum pump 20. 53 represents a condensate line leading from the chamber of the condenser 31 and is in turn c0nneet-ed through a suitable coolin coil 45 in a cooler 46,A through Va suitable ook-box 47 and to 'a suitable receiving drum 17 and thenee'through a distillate pump andZ line to a-.distillate storage tank A. 54 represents vided at. their centers with flanged openings as shown, of less size ol' diameter than the size or diameter of the pansl 40. The rising vapors from the inlet pipe 38 are thus caused to pass through a curtain of descending con-v densate dropping 'from the lower partition 41 to the lower pan 40 andF through successive curtains of descending condensate in passing around successive pans and up though the openings in successive partitions 41 and into the vapor-line 42. This vaporline 42 is jconnected vvvith'ra final fractional condenser 43, from which condenser the lightest distillate produced is withdrawn. 44 indicates the pipe or liney by Vwhich the said distillate is Withdrawn from the condenser 43. `rIhis pipe or conduit 44 is connected to a suitable storage tank (not shown) passing first through a suitable'cooling coil 45 (see Fig. 2) in a suitable cooler 46 and thence through'look-boxes 47 and a receiving drum 48. This receiving drum is connected by a suitable'line with a distillate storage tank E,.a suitable suction-pump 4Q being interposed in this line. The receivingy drum 48 is connected by a suitable line 21' witlrthe vacuum pump 20. 22 (Fig. 2) represents the exhaust rfronrthe vacuum pump. As this latter and apparatus and nected with a suitable source of supply (not shown). T his cooling medium vis preferably water. As indicated in both Fig. 1 and Fig. 2, the direct line. of this conduit 54 1s Ithrough the valve 55, coil 56 in the chamber 39 of the re-lieating .fractional condenser 31,

and thence back 'to discharge. A ybranch line 57 leads through a valve 58 into the cona cooling medium supplying conduit condenser 43, passing downward through the tubes or pipes 59 thereof and out through the conduit 60 into the return leg of the line 54.- 61 represents a valve in this line. The inlet portion'of the line 54 is connected just. beyond the' branch 57 with a branch line 62 which communicatesL into the discharge conduit 60 below the condenser 43.

63 represents a suitable valve in this line. Freni the feed-line 3 leads a branch pipe 64, by means of which the. relatively cool oil to be treated lnay be used as a cooling medium for the condensers f 35, 37. 'By using such feed-oil as a lcooling medium in such condensing operation, heat economy is effectedand the feed-oil after passing through the condenser 37 and thence thel condenser 35,

is returned to the line 3, at raised telnperature, by the return leg '65 of such conduit. 66 and 67 represents suitable valves controlling this conduit. The branchconduit 64'is connected directl' with the con` denser 37, and the feed-oi after passing downward through the tubes thereof, `passes into the returnv leg 65 through the pipe' 68. A-branehl 69.1eads from `the line 64 to the condenser 35, and `the condenser 35 is connected-at its bottom by a pipe270 with the return leg 65'. '71 represents a branch pipe orl conduit connected with the line 64 between the branch, 69tl1ereof and the con.- denser 37. 'This branch line 71. is connected with the outlet line 68 of the condenser .37.

lll)

' all essentials similar' to that illustrated in Fig. 1, excep't that the apparatus and con- y lill 72, 73, 74, 75, 76 and 77 indicate suitable valves by which the ilow ofcooling medium through this cooling systeln may be controlled and regulated as desired. 78 indicates a valve interposed in the line 3 between the branch 64 and the return le v65 thereof 'so that by suitable regulation o the valves 66, 67, 7 8, the circulation'of44 feed-'oil for this cooling system may be controlled and directed. 27 represents a steam-line leading into the still or eva-porating chamber 10, the end 28 of such steam-line being preferably in the form vof al perforated pipe located near the bottom ofthe evaporating chamber. 29 indicates a valve controlling such steam-line. The steam-line 27 is connected tb :a suitable source of steam supply (not shown).- 23 represents a residuum draw-oli' line which passes through the residnum `heat exchanger 6 and through aocooler 25 to the i'esiduum storage 26. If desired,

the oil to be treated may be discharged into a suitablc'evaporating pan -11 inthe upper portion of' the still or evaporating chamberv 10. 8a indicates a steam-line or source`of supply by which, if desired, steam may be introduced into the condensing chamber 39 of the re-heating condenser 31. This steamline 84 is connected with any suitable source of steam'supply (not shown).

Referring to Fig. 2: The-apparatus as illustrated in this figure of the drawings is innections for` high iire pre-heating of the feed-oil are omitted. I have, therefore, in these two figures of the drawings used the same reference numerals as indicating-corresponding parts. In Fig. 2 the oil-cooling and pre-heating branch line 64 is shown as provided with a branch line 7 9 connecting to the feed-line 3 beyond the residuum heat exchanger 6, and the return leg 65 is shown asv provided with a branch line connected with the feed-line 3 beyond the residuum lheat exchanger 6.4 A valve 81 is interposed in thefeed-line 3 between the connections of the lines 79'and 8O therewith, and the lines 79 and 80 arei'espectively provided with valves 82, 83.y lThe oil to be treated, after passing through the feed-line 3 and. residuum heat exchanger 6, may by means ofre'gulation ofthe valves 81, 82, 83, be passed into the cooling branch line 64 and back into the ,line 3`by the return leg 80, thus utilizing the partially heated oil when so desired.-

In the preferred embodiment of my invention in a process of distilling the composite lbasic stock containing all ,the diderent'lubi'icating oil fractions to produce lubricating distillates ready for treating and finishing as lubricating oils, the first step is the pre-heating of such stock to be treated to a muchl higher degree than can economically be obtained by the use of heatl exchangers .tional heat after the' high recaer? by which the waste heat of the system is utilized, i. e. :at temperatures below 400o F. I have found that a material increase inthe ,rate of evolution ofthe commingled vapors from this composite stock is obtained, giving an increased yield for the same charging creased charging rate, when the stock Vfeddnto the distilling chamber is pre-heated to temperatures higher than can leconomically be obtained by the use of such waste heatfl 'rate orfor the saine yield, permitting an iiivaporizing chamber held at pressuresless than atmospheric.. This pre-heating mayor may not be carrled on in the presence of steam or water vapor, the vaporizing chamber may or may not be supplied ilvlith iddi'i y preeate oi is injected therein, and the vaporization may or may not be carried 'on in the resence of steam. 4I, therefore,'pass thebo y of' oil to be distilled through the'heating element 7 in relatively small streams-v and maintain as high a velocity of theoil passing therethrough as is consistent'with the heat'trans.-

fer from such heating element'to the oil and the"mechan`ical conditionsand adaptations of the particular apparatus and discharge the heated oil into the va'porizing chamber as quickly as possible after it has been raised to such temperature. I maintain such a pressure of the evolved vapors in the heatingcoil and rlconduit to the vaporizing chamber as maybe required under the conditions of operation to substantially maintain the oil as it is bein heated, and when heated, substantially al in liquid phase. Vapori'zation of such heated oil is effected in .a single vaporizing chamber under a reduced pressure less than latmospheric. Under certain conditions of operation I have distilled oil in accordance with myprocess with as high as`26 inches ofvacuum in the vaporizmg chamber.

In a modification of my preferred process,

the oil, instead of being heated in the heat-` ing element to the highest degree of tempe-rizing chamber 10 so that the heated oilis not' subjected to such cracking temperature for a sufficient time to permit'of the cracking reaction. ln such case, if the insulation of the vaporizing chamber 10 is sufficient, it may not be necessary to supply any exterior heat whatever to the vaporizing chamber to vaporize the desired fractions. Heat may be supplied to such vaporizing chamber lO'byv means of external heat, as, for example, the furnace 13 and burner 14, to impart to the oil loss of heat by radiation or evaporization or to impart additional heat so long as the heat demand upon the shell of the evaporating chamber is not sufficient to cause substant-ial cracking ofportions ofthe oil undergoing distillation. With such fired pre-heating-of the oil, where using certain California oils, I have found by raising such oil in the heating element to the temperature of T500-800 F., and retainingthe same in liquid phase, immediately injecting such heated oil into a. vaporizing chamber under vacuum, vaporization of the desired frac- -tions of the oil takes place without cracking. If, however, it is desired tovaporize a higher-boiling-point or more viscous fraction. or fractions, some additional .heating may be required in the vaporizing chamber. \Vithout such 4additional heat supply in the vaporizing chamber, the resultant liquid oil may be maintained therein at substantially 630 F. Temperatures even above 630 F.

have been thus attained in the liquid body inv such vaporizing chamber. If only the heat lost byi radiation is supplied to the vaporizing chamber, this temperature ofthe oil in the vaporizing chamber is held uniform, i. c.,there is no differential temperature between the body of such oil and the shell of the vaporizing chamber; Furthermore, by applying additional heat to the vaporizing chamber 1nany degree less than sufficient to cause cracking or decomposition at the Contact between the shell of the vaporizing chamber and the oil therein, a still higher temperature may be maintained in such oil body. By thus delivering the oil to be distilled into the vaporizing chambeijat such increased tempera-ture,

I am able trikv attain a marked increase inthe charging rate/ and, therefore, en increased capacity for the production of highboiling-pomt and high-viscosity'oils. Also I am able to cut deeper and produce more high-boiling-point and high-viscosity oil from a given stock. In certain runs the rate of charging must be properly proportioned to permit the vaporization'of such higherboiling-point and higher-viscosity oil. The lubricating oil thus produced is of a marked superior quality. Aside from having a high boiling point and a higher viscosity, dueto higher temperatures' and deeper cuts employed, I produce .a higher-viscosity oil due to the absence of cracking compounds. A better color is also maintained andthe treating loss will be found to be reduced.

- If, however, it be not desired to utilize t is feature of high lired pre-heat and maintaining the oil in liquid phase by pressure during such pre-heat and the=immediate discharge of the highly pre-heated oil into the vacuum chamber before cracking takes place, I have found that the oil can be subiected to a progressively increasing heat materially higher than that obtained by the use i of waste heat exchangers, but to a lower temperature than that .obtainable inthe heating element 7 as heretofore set forth. For example, utilization of the waste heat of the operation lcannot economically be utilized ,to raise the oil to be distilled to above 400. 'F. Additional heat may be supplied to the oil by means of the heating element 7 to raise the temperature thereof to any desired degree below the crackin temperature 4of 'any appreciable portion t ereof, and if such temperature is not sullicient for the vaporization of the desired liigli-boiling-point, high-viscosity fractions desired to be distilled, the required'additional heat can then jrs besupplied in the vaporizing chamber without danger of cracking,.inasmuch as the temperature of theoil has been rals'ed to such an approximation of the temperature of l L the desired distilling operation that the heat differential between the body of oil to be distilled as injected into such vaporizing chamberv and the -shell temperature required for the required heat transfer from the vaporizer 10 to the oil is not suiiicient to cause such an abrupt' and excessive raise in the temperature of the-oil particles in contact with the heated metallic surface as will cause cracking thereof. I am, therefore, in this modified embodiment of this pre-heatinlg step of my invention, able to conduct suc distillingoperation at ahigher temperature without cracking than has heretofore been possible. Increased capacity, increased charging rate,- or deeper cut, is thus rendered possible.

It is obvious that this highly pre-heated oil maybe injected into the vacuum vaporizing chamber either above or into the liquid therein.

onto a spreading-pan, as indicated at 11 in the drawings, o1"other-spreading or distributing means. From the foregoing it is seen that this step of high red pre-heating of the stock to be distilled comprehends in lts several aspects the continuous distillation at a pres?y without the presence of water vapors or steam and to a temperature higher than can be economically obtained by' the use of heat exchangers utilizing the waste heat of the system, i. e.: to temperatures between 400 F. and 800 F., injecting Vsuch heated oil into a chamber maintained at a pressure less than atmospheric, which chamber may or may not be supplied with additional heat, depending upon the degree to which the oil has been heated before interjection therein, and in which chamber additional steam may or; may not be injected,as preferred,-the manner of injecting the highly heated oil into the vacuum vaporizing chamber being preferably above the surface of the liquid therein in such a manner as to expose the maximum vaporization surface to facilitate distillation, although if desired such injection may be below the surface of the liquid therein. Also the step comprehends a continuous feed, a continuous vaporization and continuous withdrawal of the evolved vapors, and the withdrawal of the residual unvaporized product either continuously or intermittently, as desired.

Preferably, all of the vapors to be distilled from the stock are vaporized and pass olf the oil together. 'Ihe mixture of relatively higher and relatively lower-boiling-point oils all vaporized simultaneously will be found to have the effect of vaporizing relatively higher-boiling-point fractions than would be vaporized at the given temperatures were such higher-boiling-point fractions vapor# ized alo-'ie after the vaporization of such l relatively lower-boiling-point fractions. All

porizing c amber intermingled and pass to of such va ors are withdrawn from the vathe condensing apparatus. It is obvious that after these vapors have been so produced, the tarry particles, constituents or mist may be separated therefrom by a' mist extraction as by the mist extractor at any preferred time before passing to condensation. For example, while I have shown such mist extractor 85 as arranged i in the vapor-line 15, the mist extractor may be arranged Within the vaporizing chamber or still 10 or as a dome thereof or in any other suitable relation'to the Withdrawal of the vapors from the chamber 10,

and prior to condensation of such vapors.

rlfhe next step of my invention is to se arate and segregate the intermingled re atively lower-boiling-point and relatively higher-boiling-point oils Y contained in the intermiingled y vapors withdrawn from the recaer? vaporizing chamber. It is highly advantageous to effect this separation in such manner-and under such conditions that the producedl condensates will be distillates of the desired boiling points and viscosities and not require re-running or reducing to provide a stock ready for treating and finishing as lubricating oil; also to remove from the respective distillates those lighter and lowerboiling-point constituents which Aserve A t( contaminate the distillates produced byv lowering the flash-point thereof.

In the preferred embodiment of a process embodying my invention, therefore, I prefe] to utilize the high heat of the interminglei vapors as withdrawn from the vaporizing chamber as a means for re-heating the con densate of the'relatively loweiboiling-poi1n oils. I, therefore, pass these intermingler vapors through closed conduits centaine( within a chamber, to which chamber is re turned the vapors of the lighter or lower boiling-point fractions, said returned vapor; being brought to a lower temperature by z controllable cooling means located within sai( chamber whereby a refiux results from sah returned vapors, and re-heating this reflu: through the meansl of the heat of the total in teri'ningled evolved vapors passing from th evaporating chamber orestill through sah passages of said chamber, thereby revaporiz 'ing and separating from such reflux thos light fractions which are low in fiaslrpoinl This step of the process may he more read ily understood in connection with the de tailed explanation of such preferred embodi ment. I will, therefore, trace the course o passage of the withdrawn inter-mingle vapors of the distilling operation throng the steps of condensation and segregatior The highly heated vapors first pass into th chamber 30 of the re-hcating fractional con denser 3l and pass through the tubes 3 thereof into the chamber 33. 'lhe descend ing condensate from the upper chamber 3 contacts with the tubes 32 highly heated b; the passage of the vapors therethrough, an this condensate or reflux is thus re-heate and those light fractions which are low i: Haslrpoint are revaporized and the result ing condensate from Which they are sepa rated is withdrawn through the pipe or cor duit 52 to the distillate storage tank D. Th effect of this heat transfer is to cause eert-.1in condensation of the highest-boiling point vapors in the'chamber 33. rlihis cor densate is drawn off from the chamber 3 by the pipe 53 to the storage tank A. 'Ih vapors passing from the chamber 33 throng the conduit 34a and into the condenser 3 are further cooled therein and the-eender sate forming therein iswithdrawn throng the pipe 5l to the distillate storage tank I rIhe vapors passing from the condenser 3 through the pipe 36 to the condenser 37 ai ily be seen that by this controllable fractional condensation of the ,intermingled `vapors of distillation I am able to produce distillates-of the desired boiling point range substantially free from low-flash-point oil, and that each of these distillates isl coinpletely distilled and forms an oil ready for treatment and finishing as .a lubricating oil. Re-running or reducing is obviated.

While in the preferred process forming a preferred embodiment of my invention I prefer to utilize the relatively 'cold fresh feed of the oil to be distilled as the cooling medium for the condensers, (such as condensers 35, 37,) of the intermediate distillates, and to use-.Water circulation as fthe cooling medium for controlled regulation of the condensation in the initial or final condensers, it is obvious that any controllable cooling medium may be used for these pur-g poses, and the invention is not necessarily limited to the use of either water or of the fresh feed stock as the cooling medium.

I claim: y 1. In the art of petroleum distillation, 'heating the oil to be distilled to the temper ature at Awhich portions thereof would crack if maintained at such temperature fora period of time sufficient to ermit the cracking reaction to take place w ile maintaining the same in substantially a liquid phase, passing `the heated oil before substantial lcracking thereof takes place to a vaporizi'ng chamber maintained under a reduced pressure less than atmospheric wherein the temperature of the oil is permitted to drop below the temperature at which port-ions thereof would crack, withdrawing'vapors from said" chamber, extract-ing from the vapors the tarry mist without substantial scrubbing of vapors in said step, and thereafter fractionally condensing the vapors into a num .ber of distillates of different boiling points.

2. In the art of petroleum distillation, heating the oil to` be distilled to a vtemperature at which portions thereof would crack if maintained at such temperature for period of time sufficient to permit the cracking reaction to take place, while maintaining the same in substantially liquid phase, immediately pgassing the heated oil before substantial cracking thereof takes place to a vaporizing chamber, maintained under' a re'- duced pressure lessthan atmospheric, Wherein the temperature of the oil isi-dropped below the temperature at which portions would crack, extracting .from thevapors the tarry mist without substantial scrubbing of vapors in said step, and .thereafter fractionally condensing the vapors. into a .number of distillates ofdiiferent boiling points.

3. In -the art of petroleum distillation, rapidly passing the oil in a relatively small stream through a heating element, thereby raising the temperature thereof tothe tem,- perature at which portions ofsaid oil would 4crack if maintained at suchteniperature for a period .of time ,suicient .to permit the cracking reaction to 4 take p1ace,.while maintaining such oil in substantially liquid phase by suitable pressure, immediately discharging the heated oil vbefore substantial cracking thereof occurs, into a vaporizing chamber maintainedl under a reduced pressure less than atmospheric, wherein portions of t-he oil vaporize, thereby'causing the temperature of the .oil to drop below the ,temperature at which portions thereof 'would' crack,

withdrawing they resultant vapors, suitably Withdrawing` the resultant unvaporlzed product, yextracting from the vapors the -t'arry mist Without substantial scrubbing of-vapors in said step, and thereafter fractionally condensing the vapors 1nto a number of distillates of different boiling points.

Signed at Richmond, California, this 25th day of Sept., 1923.

RICHARD W; misiva`

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