US2095470A - Method and apparatus for purifying liquids - Google Patents

Description

METHOD AND APPARATUS FOR P-URIFY-ING LIQUIDS Filed. 0G12.l 14, 1932 I 2 Sheets-Sheet l Oct. l2, 1937. c. B. FOLEY METHOD AND APPARATUS FOR PURIFYING L IQUIDS 2 Sheets-Sheet 2 Filed Oct. 14, 1932 `Patented Och 12, 1937 LIQUID 2,095,4'10- 4METHOD ANDAPPARATUS FOR PUmFYnG Charles B. Foley, Oak Park, Ill., assgnor to S. F. Bowser-itA Company, Inc., Fort eWayne, Ind., a

corporation of Indiana Application october 14,- 1932, serial No. 637,7'06 s claims. (c1. 19e-16) This invention relates toa method and apparatus for purifyingliquids, and more particularly to the method and apparatus of purifying mineral hydrocarbon. oils'to increase their insulating value .in electrical apparatus.

According to the present invention, the nonaqueous liquids. such as mineral-hydrocarbon oils, are treated to renderthem anhydrous and free from dissolved gases, moisture and volatile hydrocarbons which result from'oxidation of the voil when in use. In the purication of such mineral hydrocarbon oils, my present-invention is applicable `both to the conditioning of new oils and to the reconditioning of electrical oils after use.

Mineral hydrocarbonoils are refined for and` nd a wide application as an insulating medium inV oil submerged electrical apparatus because of the dielectric strength characteristics of the oil. The oils are used both as a. cooling and in sulatng medium in transformers, voltage regulatorsA and as an insulating medium in cable' When hydrocarbon oils are joints and the like. used for these purposes, they are subjected to oxidation reactions resulting from the combined action of heat absorbed from the electrical apparatus, an'd the oxygen in the atmosphere which has ready access to the oil. Complex hydrocarbons are chemically altered'by such oxidation reactions resulting in the formation of organic acids, volatile hydrocarbons, soap and deposits termed sludge, When hydrocarbon mineral oils are used in electrical apparatus such as circuit breakers, the arcing action which takes place results'inv decomposition of the complex hydrocarbons. forming elemental carbon, hydrogen, carbon monoxide, carbon dioxide, methane, and hydrocarbon vapors, all of Whichreduce the dielectric strength of the insulating medium. Concurrently with the decomposition CII due to the combination of hydrogen evolved in thezone of the arc with oxygen dissolved in the oil'. These traces of water may be in true solution in the oil and together with the .evolved 45 carbon particles of colloidal or suspensoid size contribute tothe deterioration of the insulating value of the oil.

In accordance with the present invention, I

of a portion of the oil, water may be formed tical, preferably from `28` to 30 inches' of mercury as referred to' a 30 inch barometer. When the liquid is thus forced into the highly raried atmosphere in a nely -divided form,l as for instance, by introducing the oil into the vacuum in a multiplicity of minute, preferably microscopic streams oi owing oil,- the dissolvedwaterand' gases inthe oil are caused to burst'into vapor while the oil is maintained ina liquid state even though it be in Very iinely divided or lm-like condition. The oil in 'iilmedj or finely divided condition, is then caused to ow in a more or less tortuous pathway while subjected to the highly rarified atmosphere, whereby completely to remove the water and objectionable -gases therefrom. In carrying out the broad principles of my process and apparatus, any desired type of means may be used for the purpose'of finely dividing the oil while subjecting it to a-high de- 'gree of vacuum, and while I have illustrated in myA present invention, lone type of apparatus, I

wish it to be understood that such showing is r merely by way of illustration and not by way of limitation.

In my present invention I have apparatus'which Will not only remove the water and' undesirable-gases, but will also simultaneously lter out solid impurities inthe oil, and

while this is a desirable feature of my improved process and apparatus, I wish it to be'understood that m'y invention is not limited to the simultaprovided an" neous removal of the gases, air and solid imlpurities, but comprehends a process and apparatus which will remove the gases and. water without necessarily ltering.

One ofthe objects of `my .present invention' with the purication of electrical oils whereby lthe electrical oil is converted or formed into a .porous liquid lm to which alhigh degree of vacuum is applied, whereby to cause the undesirl able water and gases to vaporize while maintaining the liquid state of the oil. Y l

invention resides in Yet another object of my electrical oils into a liquid Iiilm of porous structure by subjecting the liquid to be puriiled to a. relatively high vacuum at the point of nlm is the provision of an improved method and apl the process and apparatus for the formation of'.

provision of a method and apparatus-for thev breaking up oil electrical oils preferably while in a heated condition into a multitude of Very ne f streams of flowing liquid oil while subjecting the same to a relatively high degree of vacuum, and

also in causing said streams of flowing liquid oil to be transformed into a film-like condition whilel still Asubjected. 'to' the high degree of vacuum whereby to cause the vaporization of substantially all ofthe moisture and objectionable gases therefrom. o

Yet another object of my invention is thev provision of a portable apparatus and process for suflicientlyl rremoving* impurities from transformer and other electrical oils, andr which ap-f paratus may be easily transported from'place to place' andA attached to transformers already installed and in use and whereby the oil inthe transformer may be treated locally to remove the'impurites therefrom.

When completely refined oils are yplaced in use in Various industries certain forms of deterioration ysometimes takes place,r such as the accumulation of Water in -steam turbine lubricating oil.A f 'f Minute particles of water condensed from atmosof high voltage transformers. instance; even when` the water particles are of microscopic size and less thanl one pattini fty thousand by volume, the dielectric strength of the transformer oil will be so reduced that the apparatus will be in constant danger of being destroyed should any unusual electrical surges occur on the high tension lines or in the high tension system connected toor embodying such transformer. In transforinlgi1 practice, it seldom happens that transformers may be shut down and disconnected from the high tension system while the oil is being treated to restore its dielectric strength and seldom is a reserve amount of transformer oil .carried on handrso that the used or dirty oil may be removed.

One of the objects of my invention therefore, is the provision of means for removing impurities from transformer oil in a continuously circulating system without interfering with the o'peration of the transformer and while thetransformer remains in operation in a high tension vtransmission system.

Other objects of the invention will appear hereinafter, the novel features,^processes and combinations being set forth in the -appended claims.`

-In the accompanying drawings,

Fig. 1 shows the preferred form 'of multiple unit for use in my lm forming apparatus;

Fig. 2 illustrates one of the active elements of the multiple unit shown in 1; and

Fig. 3 illustrates more or less diagrammatically the application of my improved method of lm forming apparatus, to the restoration of the dielectric strength of transformenoil in a continuous circulating system while the transformer is in operation and' without interfering with its function.

Referring now to the drawings which disclose f one form of apparatus for carrying out my process for removing ythe kmoisture and undesirable gases from .electrical oils such, for instance, as y transformer oil, Fig. 1 shows a casing 4 having a removable cover plate 5 and provided with a liquid inlet 6 and a liquid discharge'l. The casf ing v4 may take any size or shape convenient.

Internally it is provided with means for changing or converting the liquid, such as the relectrical oil into a finely divided condition. I prefer to nely subdivide theoil by forcingit to ow in a multitude vof, very ne liquid streams while at the same time subjecting it to a high degree of vacuum. I also prefer to cause this multitude of flowing streams of oil of rvery minute crosszsection to take on a lm-like-formation while subjecting yit tothe .relatively high vacuum k whereby to cause the moisture andundesirable gases in the liquidoil to vaporize and also to burst ythrough. the oillm so that such undesirable constituents can be removed, preferably by suction, so as to leave the oil in a purified condition.y In this condition kI---prefer to cause the oil during its purification, and while subit-:etsiiA to the high degree of vacuum, to travel in an extended path of more or less tortuous nature so as to extend the time to which the oil in liquid,y k

and preferably in filmed condition, is subjected yto this high degree of vacuum, whereby substan-A tially completely toeliminate the moisture and other undesirable constituents.

threading into a portion of the Aoutlet port "I, with 7a pipe .8 rwhich, is preferably screw-threaded to i that part of the pipef'l forming: apart rofthe plate 5. In addition, I have mounted one or more shallow cups, two of the same being shown as 49--9 and each provided with a hub yll---Ni' tting on the pipe 8. 'I'he vertical, cylindrical` pora multitude of liquid owing streams of very fine cross section and preferably almost microscopic cross section.` In the form illustrated Il have shown a plurality of metallic discs I2I-l2 which are mounted in grooves I 3-I3' in the hubs M---MC When the hubs III-I0 and hubs |4-I4' are assembled on the pipe 8, they may be clamped in adjusted position by the screwthreaded cap I5 which is screw-threaded into the upper end of the pipe 8. The disc I2-I2, with those secured in the annular seats II-I I and to the grooves l 3-13' are positioned at a sufdcient space above the bottoms of the cups 9--9' to provide intervening chambers llli-46'. These 'chambers arel in communication with the passageways I1-I1' in the hubs lll-I4' with passageways or ports |8-I8' in the tubular meinber 8.

These metallic discs lZ--I2' are preferably constructed to provide a multitude of openings, holes or passages of very small cross section. I prefer to form the disc l2 in the manner illustrated .in Fig. 2 wherein it is shown as preferably composed of two metal ribbon tapes woundtightly on the hub I4 and each being provided with preferably diagonally arranged transverse grooves. 'Ihe metal ribbon I9 is provided with spaced apart transverse grooves 20 and spaced-apart raised cross bars 2| which are integral with the tape. In the present instance two of such tapes are used. The tape 22 is likewise provided with diag- In` the form illustrated, I have provided the. casing 4 at the 'center of the bottom plate 5 and.

onal transverse grooves 23 and spaced apart, raised cross-bars 24 integral with the tape. These diagonally arranged cross bars extend in opposite directions so that when the pair of tapes is wound tightly into the form of a at disc, the cross bars will be in criss-crossed relation with respect to .adjacent laminations.

Although the sectional area and shape of the passageways extending from one face of the disc tothe other, i. e., from top to bottom are preferthe naturesuch as viscosity, et cetera, of the insulating oil, or insulating liquid to be ltered, and with the nature of-the impurities of the liquid to be removed by filtering, and while I have shown these pvassageways of some length, it will be understood that any construction may be utilized for the purpose intended, of causing the liquid to flow in liquid streams of very'ne cross section, and for the purpose intended.

In the constructiond shown in Fig. 3 of the drawings, which relates to an apparatus and process for restoring the insulating properties of transformerand other electrical oils to its high dielectric strength, the amount of solid impurities in the oil, such as carbon, dust, et cetera, is very small, and the main purpose of the device shown in Fig. 1 is to sub-divide the liquid into a multitude of flowing streams of very fine cross section and to cause these cwing streams to form a liquid lm of relatively great surface exposure while at the. same time applying a relatively high degree of VVacuumthereto for thepurpose of removing water or other volatile impurities from` the flowing streams of liquid and the film ofliquid.

With reference to the device shown in Fig. 1 of the drawings, the device will also act as a ltering unit to remove solid impurities from the oil after the oil has been used in the transformer, but as hereinbefore stated, the concurrent removal or filtering oif of these impurities is not necessary to the manner of removing the moisture and other volatile impurities.

The ribbon or tape i9 and 22 shown in Fig. 2 v

vnot to. be'considered as limitative to the invention.

Referring now more particularly to Fig. 3 of the drawings which show a complete type of apparatus for removing moisture and other undesirf.

able volatile impurities from electrical oils, I have shown the manner in which one form of my inventionand in the present instance that form as shown in Fig. 1 of the drawings-may be utilized in a continuous circulating system connected to a device having electrical oil to be purified, as, for instance, to an `electrical transformer. .if

In Fig. 3, the device shown in Fig. 1, o'a device made in accordance with the teachings ofmy in- Vention, is illustrated, as at 25. A rotary pump 21A is connected by means of a pipe 28 and by means of a valve 29 to the oil-containing chamber in the transformer 26. is shown connected to the rotary pump 21 to An electric motor 30 f operate the latter whereby to pump the dirty or used transformer oil from the transformer 26 when the valve 29 has been opened. The pump 21 functions to force the oil under pressure upwardly along the pipe 3| to pipe 32 as indicated by the arrow 33. In this manner the oil is pumped under pressure into the inlet pipe 6 of the casing 4. By referring to Fig. 1, it will be seen that the oil under pressure will flow into this casing and will be forcedinto the openings formed between the tapes i9 and 22 at the tops or upper surfaces of the device, providing a multitude of oil openings or passages.

A vacuum pump- 34 operated by an electric motor 35 is connected to the upper portion of an enclosed oil reservoir 36 which, in turn, is in communication through pipe 31 and port 1 with the pipe 8 as shown in Fig. 1. It will therefore be seen that by means of the vacuum pump 34 a high vacuum may be produced in the upper portion of the oil reservoir V36 and through the center of pipe 8, the passages i1, and into the in` termediate chamber lli-I6', so as to be eective on the under surfaces of the openings or pasv sages formed in the tapes I9 and 22.

In this manner, the oil is forced under pressure through a multitude of passages of minute cross section, and as the oil thus flows in liquid condition, it will be subjected to the action ofthe high degree of vacuum in the chamber these openings or passages will tend to pull the liquid oil therethrough or cut down the frictional resistance of the walls\to the passage of the oil therethrough. In effect, the vacuum will penetrate a considerable distance along the passage formed in the tape. and will operate as a means for volatilizing or Vaporizing the moisture and the volatile. impurities. As these minute flowing streams of liquid arrive at the o uter surface of the disc and while under the influence of the high degree of vacuum, and to the exclusion of air, the streams of oil will form continuously in `film-like formation' on thelower surfaces of these porous elements l2-I2 in such a manner that the water, moisture and other undesirable volatile impurities will be extracted from the liquid oil. The water and volatile impurities are removed by means of the vacuum pump 34 directly through pipe 38 and are discharged to atmosphere through the pipe 39 as indicated by the arrow 40. If desirable, I may place in the pipe -'38, a Water absorbing" device 38' comprising acasing having Vtherein two spaced apart screens 45 and 46 with the water-absorbing chemical 41,

vsuch as granular calcium chloride between them.

When the device' is employed, the vacuum pump 34 must actithroughl the/calcium chloride. It will be understood that the porous, pervious, or reticulated elements i2--I2 constitute means for forming the liquid oil into spaced-apart owing streams of liquid very fine cross section, and also constitute mans for` forming even; reticulated, and regular filmsv of liquid oil for-'the purpose of subjecting oil in such state to the action of the relatively high degree of yacuum.

As above described, theporous bodyfof 'each' element I2-I2 embodies a multiplicity or multitude of minute, almost microscopic passages distributed throughout so that when oil is applied to" the upper surfaces or faces of the discs I2-I2', the voil is forced on one hand by the force pump the maximum effect Aof the highly rariiied atmosphere while still maintaining the oil in liquidl condition. The conversion of the oil into finely l divided condition in the manner herein described is accomplished by a substantial differential in pressure at the entrance and exit sides of these relatively small openings. For instance, on the exit side I maintain a relatively high degree of vacuum and at the entrance side the oil is subjected to varying degrees' of pressure up to a pressure substantially above atmospheric pressure. For instance, I preferably arrange the force pump 21 whereby it forces the oil through the openings at a maintained constant pressure of approximately 100 pounds per square inch more or less, it being understood, of course, that such pressures may vary in accordance with the types of oil'under treatment and the conditions connected therewith. I prefer, however, to use pressure substantially above atmospheric pressure so that the oil first has its pressure raised substantially above atmospheric pressure and is nely subdivided andis then subjected to a high degree of vacuum'sov that the moisture and gases are automatically liberated from the liquid oil.

'I'he pressure-on the oil exerted by the pump 21 may be regulated by the check valve 38 in the v.by-pass pipe 39. The check valve 38 may be set to open when the pressure per square inch on clog the passages through the elements I2-I2',

the high vacuum produced in the chambers IG- IS is useful because such volatile liquids boil while within the passages at temperatures great- 1y reduced and far below those of the normal boiling points of such volatile liquids, and form steam or vapours at a very rapid rate, which steam or` vapors will cause the dirt particles to be blown out of the passages, the whole action effecting continuousp or intermittent cleaning of the passages of the film forming means.

In other words, in addition to the' elimination of the more volatile ingredient of the mixture of liquids, such as water in oil, they application of the vacuum to the lower surfaces of lthe discs. I2-I2, also has the iect of forming at reduced temperatures vapor theelements I2 an I2'., which ywhen `emerging from the passages burst through the thin oil film covering the lower surfaces of the porous elements I2 and I2 in the form of minute bubbles,

vthereby causing the lm to become very vporous with the result that the' surface area o f the oil film exposed toA the. action of vacuum is greatly increased. .'Ihat is to say, the application of the high vacuum has the effect of' continually cleaning the passages of particlesI and greatly increasing the 111m surface.

In this 'manner the more volatile-constituent olumes in the passages-r in such as water in oil may be removed at a much greater rate and much more thoroughly than could be accomplished where vacuum is applied to the` surface of oil in a reservoir. 'The vacuum producing means show n in Fig. 3 causes the volatile vapors to accumulatein the upper portion of the reservoir 36 and to be expelled through thepipes 38 and 39 to the atmosphere. If desired, the volatile vapors may be drawn by the vacuum pump 34 through a suitable absorbent 41 such as calcium chloride between the screens 45 and 46 in the container 38', thereby preventing such vapors from re-entering the oil o r recondensing and re-entering the oil, or lowering the vacuum.

The limits of temperature within which my improved process is adapted to operate is between thevfreezing point of the water in the oils and .such high temperatures as would tend to injure the oil. .Preferably the temperature of the oils being treated should be suiciently high to decrease the viscosity of the liquid so as to cause it to iiow freely. I also find that when the oils to be thus treated are heated below such high temperature as would tendto injure the same, the

process is more satisfactory. For instance, in

the treatment of transformer oil, the temperature of 150 degrees Fahrenheit to `180 degrees Fahrenheit has been found to be satisfactory. Such temperatures are often found in the transformers while in use by reason of the electrical heat produced in the transformer windings. Furthermore, when the vacuum is applied to the liquid oil i'llm at the lower surfaces of the discs I2-I2, the boiling point of the moisture in the oil is greatly reduced. the oil to be treated has been heated, i. e., when the temperature of the incoming oil has been raised, the boiling point of the water in the oil It will thus be seen that when will be reached sooner whenthe high degree of vacuum is applied, and such boiling begins to take place in the form of minute explosions while the oil is still in the passageways, with the result of forcing back dirt particles which may tend to enter these passageways.

With further reference to Fig. 3 of the drawings, the purified or cleaned oil, after passing into' the bottom of the reservoir 36 may be pumped therefrom by means of therotary pump 40 through the pipe 4I, back into the upper portion of the transformer 2B. "The pump 40 may be operated by an electric motor 42.I A check valve 43 -opening toward the left, as indicated by the arrow 44 is preferably placed in the pipe 4I so as to prevent back-flow. Motors 30, and 42 may each be controlled by the usual and well known starting and regulating electrical devices. All three of the pumps 21, 34 and 40 may be operated at the same time so that the system may be operated for as long a period as may be desired with little or no attention from the engineer or attendant. Each motor may beregulated as to speed, depending upon the desired operation of kthe pumps to which the motors are connected.

While, for the sake of clearness, the pumping units and reservoir 36' with lter and lm forming unit 25 on top of the same are shown mounted at `different locations, the whole system may beV mounted on altruck platform so as to be portable and adapted tol be connected by means of thepipes 28 and 4I to .the lower portion and upper portion 'the film produced on the lower surfaces of the discs |2|2' are very porous and cellular; the

films are of a porous or honeycomb structure having a very great surface in contact with a partial vacuum maintained in the upper portion of the reservoir 36 and in the chambers I6--l6 below the discs l 2|2'. The Vacuum acts upon the film of transformer oil appearing on the lower ordischarge sides of `the lm forming'means thereby causing the removal of water therefrom. By maintaining a desirable high degree of vacuum such as 20 millimeters or less of mercury whenthe barometer is standing at '760 millimeters absolute pressure, the lowered atmospheric pressure on the discharge sides of the discs penetrates deeply into the pores of the filter body. This desirable high degree of vacuum is preferably from 28 to 30 inches of mercury as referred to a 30 inch barometer.

It should also be understood that the filtering and lm forming operations above described are not intended for the refining of petroleum. It is also obvious that operations used in the refining of petroleum are not adapted to the restoration of' dielectric properties of electrically insulatingoils such as oils used`ln or while in use in transformers.

The system shown in the accompanying drawings includes improved iilm producing means which, with the aid of vacuum, quickly restores thedielectric properties of transformer oils to a very high degree. For instance, transformer oil used in practice may deteriorate and break down below seven thousand five hundred volts strain when using a one tenth inch jump gap as found in a standard General Electric Company dielectric testing machine, whereas after receiving treatment for a period of but one second of time with the system and apparatus above described the oil may be cleaned sumciently to withstand a dielectric strain without breakdown of approximately thirty ive thousand volts. That this is more than ample is evident from the fact that the United States Government specications for-transformerv oils .of this type require the application of twenty three thousand volts without breakdown when ,using a one-tenth inch gap.

Such penetration causes the approaching water particles to change to their vapor phase and as this vapor passes out from the porous body it bubbles through the film of oil on the lower or discharge surface causing it to froth and thereby exposea very large surface of liquid oil to the action of' vacuum in the container for the final rapid removal of very minute traces of water.

Obviously those skilled in the art may make various changes in the details and arrangement of parts without departing from the spirit and scope of the invention as dened by the claims hereto appended, and I wish therefore not to be restricted to the precise construction herein, disclosed. This application is a continuation in part of application,- Serial No. 302,415, led August 27,-

WhatI Iclaim asnew and desire to obtain e United States is:

1 In apparatus for removing froma mixture of liquids a volatileingredient comprising ra multihlicity of closelyadjacent-capillary passageways, means for forcing liquid'therethrough, and means for forming the liquid into a multitude of liquid iilms, means for applying a vacuum to effect volatilization of the volatile ingredient while preventing evaporation of the liquid,vand means for directing the remaining liquid from said film forming means. I

2. In apparatus forremoving a volatile constituentfrom a liquid, the combination with a porous metal device having a multiplicity of substantially microscopic passages therethrough witha film forming surface on the discharge side,

of means for directing the liquid to the top of thel -sc'opic cross-sectional area and causing .said

streamsl to exude to a liquid film-forming discharge surface to 4form a film thereon, applying a vacuum to thefilm formed on such surface to vaporize the water in the oil without vaporization of the oil, and-continually removing the dehydrated liquid while supplying additional hydrated liquid to the-iilm on said surface by exuding the same from said minute streams to said surface. y i' 4. 'Ihe methodv of dehydrating viscous liquid, which consists in separating liquid not directly affected by vacuum but containing traces of water into a multiplicity of minute elongated streams each of microscopic dimensions in crosssectional area, and, exuding the liquid therefrom to spread the same into a thin liquid film, applying a vacuum to such film to Ieffect vaporization the vacuum without vaporization of the oil, and

continually removing the liquid after it has been4 dehydrated and ,supplying dehydrated liquid continuously to said lm by causing the same to exude from said streams into said film to maintain the liquid film to be dehydrated.

i 5. In apparatus for removing from mixtures of liquids a volatile ingredient, the combination with a body of relatively hard material having a multiplicity of closely adjacent straight capillary passageways extending therethrough with the spaces surrounding said passageways entirely closed by the solid material of said body, the surface of said body Where the oil exudes from said passage'waysl serving-asa means for forming a thin film of liquid, means for applying a vacuum to such thin film of liquid to eiect volatilization of the volatile ingredient, and means for directing the liquids to and from said passageways from which the liquid exudes to said film.

6. 'I'he process of removing entrapped matterl from a Viscous iiuidwlzich comprises subjecting said contaminated fluid under pressure to a degree of heat which will render it nuentlwithout deterioration, passingsaid contaminated fluid through filtering means, 'forming a film of the

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