US1685681A - Process and apparatus for reconditioning mineral oils - Google Patents

Description

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PROCESS AND APPARATUS FOR HEGONDITIONING MINERAL OILS Filed Nov. ll, 1925 INVENTOR d .an

MENGE nl'. ltlllDM, 0F WXLKINSBUJR, .MND Mill RECHT, Uh lPJENNSWLVId.

LPMUJES MD @MPPMTWUS FUR RIHEUUMJDITJEONWG milled..

Application led November l1, 1925 Serial No. 66,300.

'llhe present invention relates to the treatment of mineral oils, and particularly to the reconditioning of .oils which, for example, have been taken from electrical equipment, such as transformers, circuit breakers, 'and the like, but the invention is also applicable to the treatment of other used or impure mineral oils. l v

According to the present invention, it is proposed to subject the impure or used oil to a process of'puritication under such conditions as to substantially retard oxidation of the oil during treatment and in suchmanner as to remove Water, dissolved gases and volatilizable impurities, and to then remove other impurities such as unsaturates, resinous compounds, acidic compounds, oxidation products, carbon, sludge, sediment, etc.

According to the present invention, it is proposed also to heat the oil, to a limited extent, under conditions which will prevent overheating thereof and to utilize heat which would otherwise he wasted for preheating the oil prior to its introduction intol the reconditioning apparatus.

'llhe nature and objects of the invention may be readily understood by reference to the accompanying drawings which show more or less diagrammatically a preferred embodiment of our invention, but it will be under.- stood that we do not conne ourselves to the use of the particular apparatus shown or to the specific manner of practicing the invention, as various changes in construction and modes of operation are contemplated within the spirit of our invention.

lin the drawings the figure is a schematic view of the entire apparatus.

ln the drawings, 2 designates an oil supply pipe through which impure or used mineral oils to be reconditioned are introduced into the apparatus. The oilto be treated may, for instance, be an oil which has been used in a transformer or in a circuit breaker or other electrical equipment. @il may be supplied to pipe 2 from any suitable source through any preferred method of feed, either by gravity or otherwise.

Pipe 2 leads through the top 3 of a tank l y having a bottom 5 and having a cylindrical inner wall 6 spaced inside thereof, and having a perforate extension '7 at its lower end. This might, for example, be formed of fine mesh screen. Pipe 2 within the tank t terminates lute, and the temperature is @lill ber of the heater where it rises in thin hlms over the surface of the heating units, which units are in close proximity to each other. llt is preferred that the partitions or heaters are at such distance as to permit a maximum heat absorption without overheating any part ofthe oil, thereby minimizing oxidation or decomposition resulting from heating. llt will be understood, however, that the oil may be heated and the stream of oil broken up in the vacuum chamber to release easily volatile substances, Irases and water, in other ways.

Leading from the upper part of the tank 4l is a pipe 13 which preferably leads into a heat exchanger 14 arranged about the pipe 2. lin the lower part of the heat exchanger 14 is a drain pipe 15 through which condensates may be removed. Leading from the heat exchanger 14C is a pipe 16 that connects with a suitable vacuum pump designated 1'? and driven by a motor 18. The pump 17 maintains the pressure in the tank l at a suitably reduced pressure for the edectual separation. and removal of water, gases, volatiles, etc.. at the desired temperature. the

pressure being preferably maintained at substantially 2.5 pounds per square inch absopreferably maintained at about 150 Fahrenheit.

Suspended from the walls 6 within the tank d and below the heater 9 are a plurality of deflectors 19 which are preferably of the alternately reversed cone type. During the operation of the apparatus, oil, which passes through the heater 9, froths over the top thereof and falls onto the first of the deflectors 19. v

llt Hows successively from one deflector to another in thin films, so that any gases which remain in the oil can be readily released. From the lowermost dedector A19kthe oil falls into the bottom of the tank where it colle.

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litt@ lilith Leading from the bottom of the tank 4 is a pipe 2O connecting with a suitable pump, preferably a centrifugal or other rotary type of pulnp, 21. The pump 21 may also bc driven by motor 18. Leading from the outlet side of the pump 21 is a pipe 22 that connects with the receiving end of a reaction tank 23. The reaction tank 23 is preferably vertically disposed. and has a. conical bottom 24 which may be drained by a sludge cock 25. It may have a removable cover 9.6, and near the top thereof is an outlet pipe 27. Pipe .22 preferably discharges close to the conical bottom of the tank whereby agitation and thorough mixing of an adsorptive compound or substance is secured. At the same time, the tank has sufficient volume so that the flow of oil therethrough is very gradual and quiet in the upper part thereof. This provides for an initial turbulent introduction of the oil with a subsequent quiescent period of reaction. The outlet pipe 27 preferably connects with a manifold 28.

Leading from the manifold 28 are branch. pipes Q9 connecting with dfilters 30. Each pipe 29 preferably has a valve 31 therein, so that the flow of oil from the manifold to any filter may be controlled at will.

Filters 30 preferably include an outer casing 32, a base 33 and an inner porous shell 84, the inner shell 34 being spaced from the outer shell 32. Pipes 29 lead to the space 35 between the inner porous shell and the outer casing'. Leading from the central chamber 36 within the porous shell 34 of each filter is a pipe 37. Each of the pipes 37 has a valve -38 therein and these pipes connect with a manifold 39. From manifold 39 the oil is preferablyT conducted through a heat exchanger 40 also located about the pipe 2. From the heat exchanger 40 the o-il may be conducted through pipe 41 to a suitable collecting or storage reservoir. v

While we have described one form of filter, we are not necessarily confined to the particular form shown, as any device for this purpose which may be found suitable, may be substituted. wWe do prefer, however, that the filter plate, such as the shell 34, be of a baked porous material whose porosity may be determined by the character of the material used. Vith such a material there can be no danger of contamination of the oil with particles of lint, suspended or soluble filter material, or other substance, as might result with the use of other types of filters.

As the oil is withdrawn from the bottom of tank 4 through pipe 20, it is desirable to in t'roduce a` compound into the oil. For this .purpose we have shown a container 43 having 2a proportional feeder 44 of any preferred type at thebottom thereof, this feeder being suitably driven, preferably by a drive connection, such as belt 45 from the motor 18. With such l an arrangement the speed of the feed device may be in accordance with the speed of the pump 21. The proportional feeder introduces dry partially evacuated adsorptive material down a pipe 46 into the pipe 20. A deflector 46 is preferably provided in pipe 2() adjacent the terminal of pipe 46 so as to agitate the oil in the pipe 20 at this point to canse it to more readily mix and carry away the dry adsorptive compound or substance.

The air-tight container 43 may have a pipe at 47 terminating within the tank at 48 so that the contents of the 'container 43 will be subjected to the same partial vacuum maintained in the tank 48. This prevents any appreciable amount of air from being introduced into the o il through the proportional feeding device, and tends to remove any contained gases or air from the adsorbent material.

In the practice of the invention, the partially warmed or preheated oil enters the heatmg means for the initial stage of its puriication. It is Well known that if the oil is overheated, especially in the presence of oxygen, undesirable decomposition will result. During the practice of the present invention, any such undesirable results are eliminated.

The incoming oil, in passing through the heater, is maintained in a state of agitation, a turbulent motion being imparted thereto by the heating of oil by the parallel heaters under the maintenance of conditions of partial vacuum in the tank 4. This agitation is increased by the combined ebullition, dcgasification and vaporization of contained impurities. The effective heating of the oil is thus effected without chemical reactions of a destruct-ive or harmful nature.

Under the conditions in which the oil is heated, moisture mechanically held or dissolved in the oil, dissolved gases, such as air, oxygen, nitrogen, light hydro-carbon gases and volatiles, are continuously eliminated from the oil. These vapors and gases are continuously removed by the vacuum pump 17, so that the oil is thoroughly evacuated at this stage of the process. Some of these vapors condense in the heat exchanger 14 from which they may be removed.

The purpose of the perfor-ate screen 7 is to reduce, to a minimum, the loss of finely divided or atomized oil, this screen serving to obstruct the passage of such oil particles to the vacuum pump.

The deflectors 19 are of such a length and number as to eect a thorough dehydration and degasification, and volatilization of undesirable constituents before the oil finally drains into the bottom of the tank As the evacuated or dehydrated oil from which the undesirable volatiles have been removed passes out the pipe 20, a dryy adsorptive compound or substance is supplied thereto from the container 43 as-previously described, and is also evacuated as hereinbefore explained by the withdrawal of conlltl aaaaaai tained gases therelt'rom throu h the pipe di'. hn evacuated adsorbent is t us introduced into an evacuated oil.. This dry material is a desiccated adsorptive compound or substance having a high capacity or adinity tor impurities contained in the oil. This compound or substance may consist oi an activated or prepared charcoal, a iilter clay, silica gel, or a suitable combination ot these or similar substances in suitable proportions.. We preter to use an earth substance such as bentonite,

or a char, particularly a char especially intitl tltl

tended tor hlter ot' the tvvo.

This desiccated adsorptive substancev is thoroughly mined into the oil hy the action oi the centrifugal pump 2i., As the oil dovvs through the react-ion chamber 23, the desiccated substance vvill combine vvith the impurities, These impurities are recognized as unsatnrates, resinous compounds, acidic compounds, omdat-ion products, etc. its previously suggested the oil is thoroughly agitated in the bottom et the reaction chamber, vvhile it later passes through a aone ot quiescent reaction, The time ot reaction is suhicient to hilly enable the desiccated adsorptive substance to combine 1a'ith impurities. The reaction is more rapid due to the evacuation ot gases trom the adsorbent prior to its introduction into the oil Both condensed moisture and gases are removed :trom the cell spaces, and the total area oi the surtaces are 'thereby available tor the reactions vvhich ensue. The adsorbent reactions are both more rapid and complete due to the greater athnity oit such treated adsorbent vvith oil which has been hrst heated in a vacuum..

purposes, or a combination The oil derving trom the reaction tanlr then passes through the hlters. The hlters serve to remove the tinely divided suspended particles ot desiccated adsorptive substance, together vvith such impurities as they have collected, vvhile the reconditioned oil flows through the tilters and into the pipe 39. lltrom pipe 39 the oil, vvhich is still heated, llovvs through the heat exchanger l@ to turther heatthe used or impure oil passing 'through pipe 2 and then the reconditioned oil may he conveyed through pipe ll to any suitable collecting vessel.

.ds the oil containing the linely divided desiccated adsorptive substance passes through the tlter, the particles ct earthy material in the oil collect on the tilter plate 3l and produce a mat which serves to edectively remove hnely divided particles in the oil. lin

other vvords the desiccated adsorptive sub stance also aids the emciency ot the lilter.

With the arrangement ot filter shown, one

or more tilters can be idle by the closing ot the hill valves leading thereto, while the other iilters remain active.. This permits ot the cleaning or repair oit one or more tilters vvhile the other hlters are in operation, adapting the process removing Water and contained gases trom the to a continuous method et operation. @briously, hovvever, vve are not conlined to any particular arrangement or ty e ot hltersm Tt vvill he apparent that t e, operation is carried out under conditions vvhich reclude im onidation ot the oil as air is eaclu ed until the oil has heen completely reconditioned and cooled By reason oi the adsorptive material having heen evacuated prior to its introduction into the oil, it has a greater athnit-y 'it :tor the im urities in the oil. Because ot the tact that t e oilhas heen evacuated and the vvater and the light volatiles removed theretrom, the evacuated adsorptive material vvill have a greater attnity 'tor the impurities remaining in the oil, auch as resinous compunds, unsatnrates, etc., andthe adsorptive is not spent in removing vvater or light hydrocarbone. Therefore, less adsorptive material need be used and the time tor reaction is reduced to the minimum.. This permits the Siae ot the apparatus to be reduced and makes it particularly adaptable lor small installa, tions.

The term 66desiccated 4adsorptive suhstance99 as herein used denotes any vvell linovvn -or suitable iinely-divided desiccated substance or compound that may be intro duced into the oil and which has an adsorp tive athnity -lor the recognized impurities in the oil, but which is not dissolved thereby. The term dehydrated as used in the present specihcation and claims vvith reference to the oil, means anhydrous, as do the terms dry and desiccated, as used in connection with the adsorptive compounds.

lille claim as our invention:

l. it method ot reconditioning electric insulating mineral oil vvhich comprises first evacuating the oil, lthen introducing an "5 evacuated adsorbent into the oil and While maintaining the oil out ot contact with atmosdll `pheric gases and then tiltering the oil to remove the adsorbent While lmaintaining it out of contact with atmospheric gases.

2., all method ot treating mineral oil used tor electrical insulation purposes which comprises evacuating the oil, introducing into the oil after `it has been evacuated an anhydrous adsorbent Which has also been partially evacuated and While maintaining the oil out oit" contact `With atmospheric gases and Water, and then filtering the oil vto remove the adsorbent, the oil being filtered substantially out oit contact With atmospheric gases.

8. A method of treating electrical insulating mineral oil which consists in introducing partially evacuated adsorbent into an evacuated oil and then filtering the oil, the process being effected out ot contact vvith water and atmospheric gases.

l.' A method of reconditioning electric in sulating mineral oil, vvhich consists in hrst Hill ldd

oil, then introducing an evacuated adsorptive wm l ing the oil to remove t e spent adsorptive material, the oil being kept free of contact with atmospheric gases and moisture during the process.

5. A method of reconditioning .electric inl sulating mineral oil, which comprises heating the oil while under a partial vacuum and out of contact' with atmospheric gases, whereby dissolved moisture, gases and low boiling impurities are driven ofi from the oil, 1ntrol5 ducing a desiccated adsorbent into the oil So treated and while maintaining the oil out of Contact with atmospheric gases, and then filtering the oil to remove the adsorbent while maintaining it, out of contact With atmoseO pheric gases.

6. A method of reconditioning oils used for electrical insulating purposes, which consists in rendering the oil anhydrous and free of gases by heating it in a partial vacuum,

then adding a dry adsorptive substance having an affinity for unsaturates, resinous constituents, acidic compounds and oxidation products, and then filtering the oil, the process being effected under conditions which preclude oxidation of the oil or prevent moisture from coming into contact therewith.

7. A method of reconditioning electrical insulating oil, which consists in dehydrating the oil by heating the same at sub-atmospheric pressure in a confined chamber which precludes oxidation of the oil or the absorption of atmospheric moisture, then mixing a dry adsorptive compound therewith and allowing the same to combine with impurities in the oil, and then filtering the oil, these steps also being effected While maintaining the oil free of Contact with atmospheric gases.

8. A method of reconditioning electrical insulating oil, which consists in heating divided streams of oil in a partial vacuum, fiowing the heated oil over a defiector plate while under a partial vacuum, collecting the oil so treated, then introducing an evacuated adsorptive substance into the oil, and thereafter filtering the oil, the oil being excluded from contact'with air and water during the process.

9. A method of reconditioning electrical insulating oil, which consists in heating the `oil in a chamber from which air is excluded,

fiowing the heated oil over defiectors within the chamber, withdrawing vapors and gases from the chamber, removing the heated oil from the chamber, mixing an evacuated adsorbent substance therewith, and filtering the o0 oil, the oil being confined against exposure to atmospheric gases and moisture during the entire recess.

10. method of reconditioning electrical insulating oil, which consists in introducing the oil into a heater within a chamber from which air is excluded, heating the oil in the I heater, flowing the hot oil over a deflector in said chamber, withdrawing gases and vapors from said chamber, circulating such gases and vapors about the incomin supply of oil to thereby preheat the oil be ore it passes into the heater, withdrawing the heated oil from the bottom of the chamber, mixing a desiccated adsorptive with the oil, filtering the oil, and passing the filtered oil through a heut exchanger associated with the incoming oil supply, whereby the treated oil also serves to partially preheat the untreated oil entering the heater, the oil being confined against exposure to atmospheric gases during the entire recess.

. 11. pparatus for reconditioning electrical insulating oil, including a tank, means for withdrawing gases from the tank, a heater within the tank, an oil supply for delivering oil to the heater, defiectors in the tank below the heater for receiving the oil therefrom, means for withdrawing oil from the bottom of the tank, enclosed means for introducing an evacuated adsorbent substance into .the oil upon its removal from said tank, and enclosed means for filtering the oil.

l2. Apparatus for reconditioning electrical insulating oil including means for dehydrating and degasifying the oil and removing volatilizable impurities therefrom, means for supplying a desiccated adsorptive substance to the oil after it flows from the first named means, and means for filtering the oil to which the desiccated adsorbent substance has been supplied, the apparatus being closed against exposure of the oil to the atmosphere.

13. Apparatus for reconditioning electrical insulating oil, including means for heating, degasifying and dehydrating the oil, a reaction tank, means for `removing dehydrated oil from the first named means into the reaction tank, means for introducing an evacuated adsorbent material into the oil before it flows into the' reaction tank and after it leaves the first named means, and filtering means connected with the reaction chamber, said apparatus being substantially air-tight to prevent the oil being treated from coming into contact with air. A

In testimony whereof we have hereunto set our hands.

CLARENCE J. RODMAN. MAX HECHT.

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