US2062934A - Method of dehydrating oils - Google Patents

Description

Dec. A1, 1.936. n P. B; RENFREW METHOD 0F DEHYDRATING OILS 5 Sheets-Sheet 2 Original Filed Aug. 29, 1923 Dec. 1, 1936.` P. B. RENFREW 2,062,934

` METHOD oF DEHYDRATING OILS original Filed'Aug. 29, 1923 5 sheets-sheet 3 'A Deci l, 1.936. P. B. RENFREW- *2,062,934 1 METHOD OF DEHYDRATING OILS t original Filed Aug. 29, 192s 5 sheeishei 4 latinmail` Dec. 1,-1936 METHOD or nEnYnaA'rmG ons Paul B. Renfrew, Fort Wayne, Ind., assigner to I S.` F, Bowser & Company, Inc., Fort Wayne, Ind., a corporation of Indiana original application August 29, 192s, serial No. 302,743. Divided and this application January 1l, 1934, Serial N0. 706,311 l 11 Claims.

l `My invention relates to a method for purifying non-aqueous liquids and more particularly to the `aqueous liquids, such as mineral hydro-carbon lmethod of purifying mineral hydro-carbon oils.

`According to my present invention the nontreat'the oils for freeing them of moisture or any jee.

foreign ingredients resultinglfrom oxidation of the oil when in `use.` In the purication of mineral `hydrofcsairbon oils, my present invention is applicable both to the conditioning of new oils, and "the, reconditioning of oils after use. `Mineral hydro-carbon oils are adaptable for manypurposes among which are lubrication purposes and electrical` insulation purposes. In that type of oilsused for electrical` insulation purposes, the oilsareusfed both as a cooling and insulating mediumin the transformers and voltage'regulators, andas aninsulating medium in cable joints and the, like. After considerable use for these purposes, the oils are subjected to oxidation, resultingfrom the combined action of heat absorbed from the apparatus, and the oxygen in the atmospherewhich has access to the oil, resulting in the formation of organic acids, volatile hydro-car- `bons and sludges. In the use of these oils in the circuit breakers, the arcing `action which takes place decomposes the hydro-carbons and considerably reduces the dielectric strength of the insulating medium. concurrently with the partial decomposition of the oil, water or moisture is `iormedl These traces of water may be in true soluticnin the oil and that, with the evolved carbonparticles of colloidal or suspended size, con-` tribute tothe deterioration of the insulating action` of theoil. In accordance with oneaspect or phase of my l process, l'. treat non-aqueous liquids including oils, and particularly including electrical insulating oils to render them moisture free.

In another aspect of my invention I filter these non-aqueous liquids, including oils and particuf larly electrical insulating oil, to render them free of carbon particles or `other suspended foreign matter. In accordance with my improved process, the treatment to render the non-aqueous liquids free from moisture' may be carried out irrespective of the filtering operation, or, if desired,

` q may be carried `on either successively or Similitaneously with the filtering operation,

In accordance with the broad features of my invention for rendering the non-aqueous liquids free from moisture! introduce the non-aqueous liquids under pressure in' very finely divided condition into a vacuum `chamber from which the air` and other gas is excluded, and which is maintained under a relatively high degree of vacuum. The non-aqueous liquid introduced into the vacuum chamber is preferably heated and its pressure is raised considerably prior to and for the purpose of introducing the liquid into a vacuum chamber. The vacuum within the chamber is maintained relativelyhigh and when the liquid is thus forced into the highly rareiled atmosphere in a finely divided form, as for instance, by introducing the liquid into the vacuum in a multiplicity of minute, preferably microscopic, capillary streams of flowing oil, the dissolved water and gases in thel non-aqueous liquid are caused instantly and automatically to burst into vapor, which is immediately carried off, while the oil maintained in the liquid state even though in finely divided or film1ike condition is recovered.

In that portion of my invention relating to the process of filtering the non-aqueous liquid, I prefer to force the liquid under considerable pressure through fine openings or capillary passages preferably in hard, non-yielding material such as metal for the elimination of the suspended matters and other solids. In particular, I prefer to force the non-aqueous liquid up- Wardly through the filtering medium whereby sludge or suspended matters entering on the back plate pass through the underside of the filtering medium and will be free from the filtering surface dueto the action of gravity. In another aspect of my invention, by forcing the liquid upwardly through the ltering passages and thence causing it to flow in a generally horizontal direction, while particularly under the action of a relatively high vacuum, I am enabled successively and/or simultaneously to `eiect the-`l evaporation of the moisture content of the nonfiii aqueous liquids to render the liquid anhydrous.

Yet another object of my invention resides in a process for the treatment of electrical insulating oils by forming the same into a liquid film of` porous structure by subjecting the liquid to be purified to a relatively high vacuum at) the point of lm formation and in such a manner that the 'more volatile impurities will change to their vapor phase before being removed and by so` doing will convert `a liquid film during formation into a froth-like or porous structure of greatly increased area of exposure and surface contact,V all of which is carried out under f a high degree of vacuum and with the exclusion of air.

` AYet another object of my invention resides in the provision of a method for the breaking up of electrical insulatingfoils preferably while in a heated condition into a multitude of very fine streams of owing liquid oil while subjecting the same to a relatively high degree of vacuum and also 'in' causing said streams of owing liquid oil to be transformed into film-like condition' while still subjected to the high degree of vacu` um whereby to cause thevaporizationof substantially all of the moisture' and objectionable gases therefrom. Y

These and other objects of my invention will be apparent from a perusal of the following speciiication when taken in connection with the following drawings wherein l Fig. 1 represents an elevationmostly in sections yof one form of apparatus for carrying out one tric properties thereof;

Vform of my improved-process;

f Fig. 2 represents in plan one lof the ltering and moisture-removing elements lcomprisingffa metal tape having spaced cross bars on one side thereof Fig. 3 is a plan view ofthe apparatus'shown in Fig'. 1;

Figure .3*l is a detail of parts of the piping system; l

` Fig.g4 is a side elevation' viewed from theright hand sideof Fig. 1;

Fig. 5 represents a complete circulating system when the apparatusshown in Fig. 1 is connectedto a transformer for the purpose of purifying the oil therein and recovering the dielec- Fig.'6 is an elevational 'view of theY oat-controlled valvel mechanism; i

Fig. 7 is aA plan view partly in section of the `doet-controlled valve.. and

Fig. 8. is a sectional elevation taken'. on the line 8`8 of Fig. "I, looking in the direction of the arrows.

1 The present application is adivisional application of `my co-pending apparatus applicationSerial No. 302,743 filed August 29, 1928.

whichv involves the process of removing mois- In the present application I have selected the described apparatus as one which will accomplish a dual treatment of the non-aqueous liqnids,` towit: an apparatus for rendering the liquidv anhydrous and/or also for filtering the same. These operations are separable anddistinct and my invention includes these l*two treatments as distinct, separable and individual processes and'as not dependent one upon the other. particular, inv carrying out the ltering step ture from the liquid, I force the liquid under substantial pressure through a porous orr perforated structurey wherebyA to sub-divide the liquid `mwa-multitude of relatively ne flowing liquid streams which are suddenly subjectedto a relatively high vacuum, whereby `the moisture and other foreign gases in the liquid are caused vinstantly to vburst intovapor and to be automatically removed from the liquid. The liquid itself 'is by .this action and/or itsy subsequent treatment, transformed into a iilm-like-state, which is continuously subjected-.to this relatively`high vacuum tol carry out the substantially completeremoval of the moisture and foreign gases which are immediately withdrawn.y The thus treated and puried oil is collected for reuse.

By thus forcing the non-aqueous liquid through sufciently small openings and into the presence of a high vacuum I am enabled also eiiiciently to remove objectionable solids from the non-aqueous liquid, thus to effect filtration thereof. vI shall describe the ltering process and the process of rendering non-aqueous liquid anhydrous separately. I shall rst describe the treatment of the non-aqueous liquid whereby itlis forced under pressure through the passages in the porous element which are of size suiciently minute to filter the liquid.

In carrying-out my invention I prefer to use the apparatus shown'in the accompanying draw- In Fig. 2 I have shown a type of a. com-- v'bined filtering and dehydrating element in the ings.

form of a ribbon-wound disc 9 comprising a thin metal ribbon Il) wound tightly on a hub II and havingone side smooth and lthe other side provided with spaced-apartV raised vcross ribs I2. This ribbon may be approximately in width, .0036" thickness and the raised cross ribs may be .0004", the total thickness of the ribbon,'including the crossv ribs being .004" in thickness. When the tape is wound compactly, each passage may i be 1A," in width and .0004 in depth between the edges of the ribbon and fromone side of the flat .disc filter element 9 to the other side-thereof.

Such elements may have their dimensions vary,

those lset fortlibeing by way of illustration of the capillary nature of the minute passages. In

lvarying the dimensions 'of the grooves, for instance, by renderingv the passageway slightly larger, the filtering operation may be altered or even eliminated-while preservingl that-portion of my process relating to theelimination of the moisture and objectionable gases in non-aqueous liquid.

In theformation of the elements 9 for use in rthe process of ltrationto accompany the process in Fig. 1.A 'Ihispipe 20 is provided wltha series,

of perforations or ports 2| which are'respectively in communication with the chamber I6 of the individual units. These units are preferably so arranged that their entrance sides face downwardly so that when used for the purpose of filtration the heavier particles of impurities in non-aqueous'liquid may fall by sedimentation to the upper sides of the cups I4. It should be understood that fine particlcsof carbon and other solid impurities may cake on the lower sides during filtration and willact to filter the incoming liquid so long as `such caking remains suiciently porous below the lowermost unit; The iiat disc 22 maybe mounted in position concentric with the units by reason of thehub 23, which iits over vertical tube or pipe 20. This disc 22 may act as a collector for'the impurities which fall by sedimentation from the lower face of the lowermost unit.

When the-multiple unit mechanism shown in Fig. 1 is to be cleaned mechanically, impurities may be scraped from the bottoms of the units for collection on the tops of the cups I4 and on the upper surface of the plate 22. Over the upper end of plate 22 is placed a closed cap 24 so asto iit ontop of the uppermost hub i5. Screw threaded into the top of the cap 24 is a nut 25 which` serves as an abutment adjustable in elevation. A canopy top 26 ls provided with anV interior central downwardlyprojecting cylindrical member 21 which may t over the top of the series of units is rigidly connected to the plate |1 and the latter is bolted by means of the bolts 33 `to an opening'in the top of the reservoir 32. The

" reservoir 32 is vsecured by the bolts 34 to the bed plate `35. It will thus be seen that since the reser voir 32 is secured rigidly to Ythe bed,plate. 3,5 and the casing is rigidly bolted to the reservoir 32, the canopy 26 and the plate-21 rigidly connect the mechanism tothe tank or reservoir` 32.

The chamber 36 is entlrelyenclosed and is sep'- aratefrom the interiorof the tank 32, except through the pores or passageways of the combined dchydrating and filter` elements, the chambers I6. theports 2| and the interior of the pipe 2|L` `It will thereiore be evident` that when oil or other liquid to b `treatediis introduced into the chamber'36 from the pipe 31 in Fig. 1` ln the direction indicated by the arrow 36 the liquid cannot escape. except as indicated by the upf wardly directed arrows under the filter elements I 9 and the downwardly directed arrows in the tube'20. e

When the liquid to be treated is more. or less viscous it may be heated by the heating elements `all. 39; which may be er the `electric typ'ewitn downwardly extending electric heating coils 4c,

as indicated diagrammaticaily by the dotted lines in Fig'. 1. These heating elements may be placed i li back of vertical baille plates 4|, 4| or in such posiltions as to eiect thorough mixing of the heated liquid by convection currents.

I r Fig. 3 I have shown a pump 42 operated by the `electric motor`43. This pump is adapted to .i pump the liquid to be treated from a pipe 44 into 50` i and 49, as shown in Fig. 3*. This check-valve 41 the pipe 45 and out through the pipe 46 to the i pipe; 31. `In a by-pass around the pump 42 is connected a check-valve 41 between` the pipes, 43

is adaptedto open `upwardly from the'pipe 43 to `the `pipe 49 when the pressure in the pipe 31 and `therefore in the chamber 36 exceeds a predetermined maximum. This may occur when the filters and dehydrators become so clogged with impurities that the rate of treatment is slowed down considerably. The check-valve 41 in the by-pass around the pump 42 will circulate the liquid ba'ck to the entrance side of the pump until the pressure in thechamber 36 is reduced. Therefore, neither the pump 42 nor themotor 43 will become stalled when the pressure in the chamber 36` where the units are located reaches a predetermined maximum.

As shown in Fig. 3, the bed plate 35 is of suillcient area to have mounted thereon not only the reservoir 32 'and the closed casing 30but also the electric motor 43 and the pump 42. By referring to Fig. 5 it will be seen that the pump 42 may be connected by the pipe 44 `to the oil ressuiilcient pressure the oil will be -illtered by the filter elements 9. These ilter elements are mounted in` multiple. there being ten shown in Fig. 1. Y The filter elements are immersed `in the oil in the chamber .36 and therefore the hydraulic pressure` is substantially equal over al1 of the vlower or entrance sides ofthe lter elements.

at the discharge sides of the lter elements andthenceinto the tubev 20 and down the latter into the reservoir 32.

The same electric motor 43 which drives the pump 42 may also be connected to drive the pump 52 to pumpthe filtered oil from thereservoir 32 -lnto the pipe 53 andthence into' the top of the transformer reservoir when the valve 54 `is open. The arrows in Fig. 5 indicate the ow of the oil from .the transformer and back to the i transformer.

As shown in Fig. 3," the pump 52 is not connected directly to the'pipe A53. The dirty `oil pump `i2 and the clean oil pump 52 may both be` mounted to be driven by the motor 43. 'This low position is particularly desirable for the clean oil pump 52 so that its suction connectionthrough the pipe 55 may always receive priming liquid from the Voil in the reservoir 32. `In fact the depth of the oil in the reservoir 32 should not fall below that necessary for keeping the clean oil pump 52 primed with oil. This is particularly true when the vacuum apparatus hereinafter described is employed in the oil purification system. The minimum level of the oil in the chamber 32 is indicated by the dotted lines 56 in Figs. l and 4. The section pipe 55 will then always be below the minimum level of the liquid in the reservoir 32 and the pump 52 may be continuously .operated with the assurance that lt will always pump oil from the reservoir 32. as indicated by the dotted arrows in Fig. 4.

I'he float controlled valve shown in Figs. 1, 6, '1

er. whereas when it falls to the depth indicated by the level 56. the oil will be automatically directed back into the reservoir 32.

The clean oil pump 52 is mounted in a pan bracket 51 which is secured to the vertical plate 58 attached to an opening in one side of the reservoir 32.` Whether the oil is pumped to the transi former or back into the reservoir 32. it first passes fromthe pumpq52 `into the Vpipe 59 and thence through the opening 60 in the plate 6| which is bolted to theplate 53. Secured tothe plate 5| is a manifold 52 having passageways for the `ow of the oil, as indicated by the arrows 63, 64 and 65. The port 66 isin communication with the port 60 through the manifold 62. The port 66 is connected directly to the pipe 53.

.At the center ofthe manifold 62, `midway between the ports 60 and 66, is a cylindrical valve 1 Connected'to-.the stern 69 'of"thel"cylin'drica1 valve 61 isa rod 10 at the :upper outer end of `which, is a float ball 1 I which; isadapted to foat in the Yoil in the reservoir 32. Whentlis float is at the elevation indicated by the dotted lines "'in'Fig.

f ltby reason of the high oil levelfindicated'by'the 10k dotted "lines 12,'fthevalveports lifwill'be inthe positions shown'in Fig. 8. In the lowerfportion 'of the valve 61is an elongated port13 and in the .bottom ofthe manifold is aosimilanport 14.

When the depth of the oil inthe reservoir falls below the level indicated bythe dotted lines 12,

v `the valve'l3, -14'tendsv to open and when the level 58'is reached, vthe'float 1 I drops'to such a `low positionfthat the valvel port 13 Awill bev in full registry with 'the port 14 in the manifold. Then the maximum amount of oil will `lay-pass from the fpurnp 52 throughthe pipev5il, port 60,'manifold 62,` port 68 and ports 13 and 1llmfbackl intothe reservoir 32, because the port 13 'communicates z vdirectlywith the interior'of the reservoir 32.

While'therefore the valve 61 maintains communiv` cation lbetween the ports 160 a-nd'66'atall times,`

` `the opening o rfthefports 13,71Qmwill establish a byi-"passbaclrtoy the reservoir 32 whenv the depth t of the oil in thelatter fallsbe'low a predetermined 1 level.I When noi-"oil isftbf4 be pumped into the transformer, the ,valve 54 Amay vbe A:closed and q nevertheless the clean oil pump may continue its )operation whenK the by-pas'sfis open through the L ports v13 andld. ySo Valsowi'nnzthe valve'54is closed,the .by-pass illustrated in" Fig. 3F lwill perf. A mit continued operation of 'thedirty oil pump' `'62- j without: ,stalling fthe' same.l When,j` however, k filtering operations continuer with the valve 5I open andthe valve 54 "closed, the closing of the Vports 13 and 14 by the level of Vthe liquid reaching that designated12 inFig.'r 1 will* automatically stall thepump 52 and stop theelectric motor t3 fwhich'is protectedA by the'usual electric circuit `breaking devices.'It will also be seenthat jeven g 'when the valve`g54'iskept openyther depth in the v transformerreaches thefpoint where no more oil can be pumped into the same the cleanoil pump r52. will be stalledv when the depth of the oil in the reservoir 32 reaches 'the lefvelv12 where the valve e 13,114 will be closed. However, itis intended that the amount of* oil in the reservoir and in thev transformer 5l)v shall be proportioned so that the pumping system mayrgo on continuously to `co`n I kstantly circulate the oil sojlong as the electric current'is supplied'to the motor 43 vto operate ,the

samer;V The nature ofy the liquid being filtered will Y f largely determine the'rate of filtration and where there are-fconsiderablefsolid 4impurities in` vthe liquid being filtered,` the filterr elements will tend` to clog graduallyand therate offltration dev crease, which will tendto decrease the amount to -fall toward the 'minimum permissible depth inofffilter'ed oil supplied tothe reservoir 32.l lIt Atherefore becomes desirable to provide the auto-` maticr float control valve to byu-pass they oil from theclean oil pump 52 backtothe reservoir l32 whenthe depth of the liquid in the reservoir tends dicated bythe dotted lin'e 56.1 r A .Whendesirei the box 16 maybedetached and removed and the vacuum pumpremoved therefrom iso as yto permit renewal ofthe calcium chloride. As shown in Figs. 1 `and 4, the suction l a 1port11 is Yat the upper end of the vertical passage- ,Y Y way 90 at one side of the box'16 so that the water 7 5` vapor, may becompelled to pass down` through a 2,062,934 f L81 having diametrical ports 68, 88 for maintaining the port 9| and then up through the calcium chloride inthe box 1'6.

The vacuum pump may alsovbe operated as a blower by closing the valve 83 and opening the ,valve 84 so as topermit the pipe v92 which is open tothe atmosphere to act as a suction pipe. When the valve 8j is closedY andthe valve B2 is open, air maybe-drawn by the pump v15, as indicated by the arrows 93,'94 and 95, from they atmosphere and blown into the chamber above the liquid'in trie reservoir 32 and thence upwardly through the pipe intothe various chambers I6 to produce soufcient pneumatic pressurethrough the multiplicity of pores,or` passageways in the laminated elements to force the caked solid impurities from the bottoms of the filter elements from which Vsuch impurities `will drop on the top's of the cups i4. At intervals, depending upon the amount of solid impurities. filtered Vfrom the liquid being treated, the pump 15m`ay be operated to flush the filter units with compressed air to ,forcethe solid cakedimpuritis from the entrance sides of the lter elements and. thus restore the eiiiciency of the filtering rapparatus until such time` as it may become desirable to remove the canopy 26 and the housing 30 to vpermit mechanical cleaning of the ltering units.

The process whereby moisture and other deleterious gasesl are' automatically, removedV from theliquid to be treated is accomplished, in-principal, by vforcing the liquid to lflow underrpres- VVs ureiinrelatively vii'nehstreams or in sub-divided condition, and while ,in such statenlsubjecting it tothe action of relativelyhigh vacuum whereby the moisture will burst into` vapor and be re-` leased from the liquid.

Referring more in particular to a method forv I have,A therefore, provided'an improved method for so treating the oil by applying a vacuumy to the discharge side of the porous elements 9 through which the oil is forced. in minute flowing streams under pressure, so as to remove the Water from the oil and preferably without interfering with the operation of the transformer, and without necessitating its lbeing shut down or disconnectedV from. a high tension system'` In other words,the oil in the transformer may be treated torestore its dielectric strength without shutting down a transformer, or disconnecting it from the system in which it is being used. Y l

For this purpose a vacuum pump 15 is mounted on the box 16, which in `turn is mounted in an opening in the reservoir 32 and connected thereto so as to be hermetically sealed. The box 16 'the upper interior portion of the reservoir 32.

A' pipe' `18 is connected between the top of the vacuumjpump 15,to the atmosphere'jas indicated by the arrow 19. A by-pass pipe 80 is connected betweenthe pipe 18 Aand the interior upper portion of the reservoir 32. When the,l valve 8| is open and the valve 82 is closed and the valve i l moved fromthe oil with the result that when it 83 `is also` open and the valve 84 `'is closed, the

y vacuum pump maybe operated to applyV the vacuum, asindicatedby the downwardly curved arrowsin` the tube 2l and the arrows indicated by? the reference numbers 86, 81 and 88. 'I'he vacuum pump may be operated by the electric i motor 89 shownin Fig. 4. While the vacuum 1in `the elements 9 will force the liquid oil therethrough 'andthe high degree Yof vacuum acting onthe other end of these openings or passages will tend to pull the liquidY oil therethrough or cut down the frictionalreslstance of` th'e walls 'to the passage lof `theoil or liquid therethrough. In

`eect, the vacuum will penetrate a considerable distancefalong the passage formed in elements 9and will operate as a means for volatilizing or `vaporizing the moisture and the volatile impurities.` As these minute flowing streams of liquid q i arrive at the` outer surface of the elements, and f while under the influence of the high degree of ents of the oil to burstv into vapor.

vacuum and to the exclusion of air, the streams vacuum pump. In particular, when the liquid oil emerges from the porous elements, it spreads in `a thin lm and it is the application of the vacuumin the chamber i6 that is most effective in causing the water and other volatile constitu- When `a high vacuum is produced and the temperature of the q oil has been raised bythe heating elements 39 the boiling point of the microscopic traces of moisture and water has been so lowered by the application of the vacuum that all of the small traces of water in the oil, as soon as` it emerges `from the passages vof the porous element into the chamber `I6 will Vaporize and cause frothing `so as to `greatly increase the film surface of the l 50 oilY and decrease the thickness thereof, thus'exposing a maximum area and quantity of oil to the vacuum to remove even microscopic traces of the water from the oil and thus restore the in- `sulating properties ofthe oil or its high dielectric les strength. Thus the water traces will be reis pumped back to the transformer it will be in very excellent condition as to its desirable qualities andparticularly as to its insulating proper- `ties and high dielectric strength.

It should be noted that while the` method above described is particularly adapted for dehydrating `electrical insulating oils, such as those used in electrical transformers, to restore the electric `insulating and dielectric properties thereof, it may have a general application in that a more volatile ingredient may be removed from a mixture of liquids by the application of the vacuum producing apparatus.

'Ihe multiplicity of minute frs 20. By application of the vacuum to the dis-4 charge sides of the elements the smallest traces of Water maybe removed from the insulating oil, and as before stated, the preheating` by the four electric heaters 39 shown in Fig. 3 facilitates not only the removal of the solid impurities, but lalso all of the water 'from the oil.

Obviously those skilled in the art -may make various changesin the details and arrangement of parts without departing from the spirit and scope of the invention as defined by the claims hereto appended 'and I wish therefore not to be restricted to the precise arrangement herein disclosed.

I do not herein claim the novel apparatus for treating liquids in the manner `disclosed herein since the same forms the subject matter of my application Ser. No. 302,743pfiled August 29, 1928,

of which this application is a division. Said application wasissuedY as Patent No. 1,951,809, Vdated March 20, 1934.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States'is:

1. The process of removing moisture and gases `from oil which comprises forcing the-oil under super-atmospheric pressure upwardly through capillary passages in a tank maintained at subatm'ospheric pressure to release the moisture and gases from the oil, collecting the oil and separating the gases therefrom, and flowing the oil toward the bottom of the tank while exposed to the reduced pressure in the tank.

2. The process of removing moisture and gases from oils comprising raising the pressure of the oil substantially above atmospheric pressure and utilizing said pressure for forcing it upwardly in very ne streams through capillary passages at a temperature below 160 degrees Fahrenheit into a rareed atmosphere maintained constantly under a high vacuum to release the moisture and gases from the oil, and separating the moisture and gases from the oil. Y 1

3. The method of dehydrating oils which consists in forming a multiplicity of minute streams of liquid oil and directing the same upwardly while subjecting the same to arelatively high degree of vacuum, flowing said streams laterally into film-like form while subjected to said vacuum, causing the dehydrated oil to ow from such surface films by gravity while removing the released moisture. l

4. The method of dehydrating oil which consists in forming a multiplicity of minute streams of liquid oil and directing the same upwardly to a plurality of superposed spaced-apart surface lms, applying a vacuum simultaneously to all of such surface lms to vaporize the water in the liquid and effect frothing thereof, and continuously permitting the dehydrated liquid to iiow from such surface films by gravity while supplying additional hydrated liquid to the bottoms of said surface iilms.

5. The method of increasing dielectric strength of insulating oil, which consists in filtering the oil by means of a multiplicity of pores through which the oil ows upwardly and spreading the oil into a thin film at the upper limit of said ow, and applying a vacuum to such upper lm to re- `move microscopic traces of water from the oil by volatllization and evaporation of the water in the oil as it emerges from such pores into said thin film and thereby increase the dielectric strength and insulating properties of such oil.

6. The method of dehydrating oils used for electrical insulation, which consists in forming a thin oil film on a horizontal supporting surfacel by feeding the same with a multiplicity of closely adjacent minute streams of oil of microscopic ldimensions in. cross-section andowing upwardly to continually replenish the film with oil to be Y dehydrated,v andapplying. a; vacuum 'to such' coni-K tinually forming thin lm to effect volatilization ofthe water in the oil andthefrothingv of the oil in the film toeffectdehydration ofthe oil.

electrical insulating oils'which consists in filtering the voil while causingit to ow'upwardly ina multiplicityof closely adjacent "n'iirrutel streams,v f spreading out the oil at theupper ends of said afthin Vfilm on ahorizront'al s' supporting surface,farid applying a 'vacuun'r vm' 1 minute streams into such film to effect volatilizatio'n Of-the'waterin ftheqoil to remove such water simultaneously with-the continuation of such filtration of the oil.

8. The method of treating oils. which com# prises forcing the'liquidoilunder` pressure upwardly `throughcapillaryv passages of sumciently minute cross section tovremove solidl impurities,

applying a relatively .high vacuum tothe discharge end of such capillarypassages to cause '1. The method of. removing'` impurities' from moisture in' the the vapor and collecting the oil.

9. The herein 'described' process oftreating oils which comprises forcing the ,heated liquid oil under substantial pressure upwardly through capillary passages to remove suspended solids', and subjecting the oilA at the discharge 'side of y said passages to relativelyY high vacuum to releaseY moisture therefrom.

oils which comprises forcing liquid upwardly through passagesof such smallrcross section so asto sub-divide the oil into microscopic-flowing liquid streamsv while subjecting the; flowing streamstotheaction of avhigh vacuum. l

11. The process of treatingroils which comprises forcing` the oil under super-atmospheric pressure upwardly through Vcapillary'passages of 'sufliciently minute'crosssection' toVv remove solid impurities, intov a vacuum chamber` where .moisy ture vapor .is withdrawn from the oil,` and foreing cleaning fluid through said passageways downwardly in'theopposite direction whereby to clean s -aid passageways.l I

- PAUL B. RENFREW.

oil ,to'burst'i'nto vapon'removing 10. 'The herein describedA processl of .treating

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