US2451668A

US2451668A - Process and apparatus for reconditioning contaminated oil

Info

Publication number: US2451668A
Application number: US479462A
Authority: US
Inventors: Charles J Egger; Robert H Webster
Original assignee: BUCKEYE LAB CORP
Current assignee: BUCKEYE LAB CORP; BUCKEYE LABORATORIES Corp
Priority date: 1943-03-17
Filing date: 1943-03-17
Publication date: 1948-10-19
Anticipated expiration: 1965-10-19

Description

Oct. 19, 19 48. c E R ET AL 2,451,668

PROCESS AND APPARATUS FOR RECONDITIONING CONTAMINATED v OIL Filed March 17, 1945 iil IIIIIIIIIIIIIIIIIIIIII II III II II Patented Oct. 19, 1948 UNITED 1 Es 93515 i mass AND m EEQQN- DITIQNiNG ooN'rAluiNn'rnn 9 Charles J. Egger and RobentH. Webster, :Gleveland, Ohio, assignors to The-, BuckeyeqLa-boratorieslCorporation, a corporationtqfqhio Ap i a i n Ma 1 1943, $ss el Neease 1 Our invention relates to reconditioning equip ment tor oil and process for treating oil.

' It is a well known' fact that when lubricating oils of predominantly petroleum character are used in internal conibus'tion'engines, their life of service is dependent on the rate at which cont'aminants increase relative to the quantity'of oil used. These contaminants may be introducedfextraneously 'or may occur as products of decomposition or of chemical changein the oil itself. Petroleum-oils are generally comparatively stable, as means'of refining have improved this property,"-but severe operating conditions may cause oxidation, or thermal decomposition, or both, to occur; The products of suchdeterioration include carboxylic acids, alcohols, ketones, esters, and even'aldehydes, of varying molecular wei'ghts and degrees of chemical activity. Thermal decomposition alone will cause the formationof hydrocarbons foreign to the originaloil, some of which are volatile while others may be of'sufiiciently high molecular weight as to be waxes-or solids; in addition there may be' ultimate destructionof some constituents to produce carbon, which -per-' sists as a solid in the lubricant, and hydrogen.

Impurities which frequentlyare'introduced extraneously include water, either from the atmosphere or from the combustion of the fuelused, fuel which is not consumed in the normal operation of the engine or is introduced'otherwise, and solid particles such as road'dust, metallic particles, metallic oxides, carbonaceous matter and the like.

It will thus be' seen that the volatile impurities include the oxidation and thermal decomposition products of" comparatively low momem r weight, unused fuel, and water; Adverse efiects have been shown table-attributable to ea'ch'type.

Water forms'the nucleiaround which sludges accumula'te, the oxidation products are much more active chemically than the hydrocarbons in'that they cause'loss of metal in the endear mechani s'm by corrosion, and the volatile contaminants of hydrocarbon structure, that i-s'; "the fuel and somethermal decomposition products reduce the viscosity and'other physical properties of the oil,

thus affecting the film factors.

In the case ofpetroleurn oils whichare used in the electrical and power *industriesi' theefie'cts or deterioration "insert/ice "have long been known to cause seriously adverse 'results in tl'ie operation of the equipment and apparatus in'which such oils -are utilized;' The "efficiencyof-hydr-ocarbon oils for such purposes isfliependen'flalmost 'complet'ely upor'r'the dielectric properties characteristics and other 11 Claims. (01. 196-316) of these oils, and these qualities are greatly diminished by factors such as'theintroducti'on,

formation; or incidence of water and of oxida tionrproducts. :It has been found that the rate of formation' of oxidation products is greatly influenced' bythe presence of Water and of atmos pheric oxygen andzcarbon dioxide, and that when the 'prese'nce'of these agents can be' eliminated or heldto an exceedingly low ''-proportion, the" useful life of :these'oi-ls can be prolonged for a very rconsiderableperiod of time, and that 'cor= rcsion eifects in the equipment become practically none-existent. I

, Ina widerangerof industrial applications,the useful -'li-fe' of Z'oils'is frequently found to'=be dependent upon the rate *at which extraneous =impurities iareii'ntroduced, andMonsequently upon a criticaliconcentration of these impurities. In quenching-2011s,- the ratea of heat transfer will be greatly afiected by the presen'ce ofiasmall amount of water;- in vacuum pump :oils, air compressor oils," and adsorptibn oils, 'the' "incidence of gases and: wolatile contaminants; either "in solutionor present -as'separate phases is unavoidable from of .volatileliqiiids as' fuels, as in internal combustion' engines. For example, in the operation of steam turbines, it has been found impossible in practice to prevent theintroduction' int'o the lu bri'cating'i-oil' of considerable' amounts *of- "condensate a'nd :g'ases. Removal of such contaminants will decelerate the rate of formation of oxida-'- tion products generally recognized to be unde g.,. .M V.

Solid impurities can be removed from an oil by filtration, and the higher molecular'weight con-' tamin'ants"have not been generally proven to 'be so greatly deleterious to the functioning of the lubricant, but in treating contaminated' oils it is recognized that thetotal and efficient removal of the volatile contaminants has not been yet satisfactorilyiachieved;

Anob'ject'of our invention is to remove volatile contaminants ti om anoilby'heating the oil,-'in I troduoing' it into a chamber in finely dispersed globular partieles, the chamber being kept atsub-atmospheric pressures, and being heated While the oil is in a finelydispersed dorm to a'ssure complete vaporization and removal of diluents and other low-boiling contaminants from the oil being treated.

Another object of our invention is to remove volatile contaminants from an oil by distilling the volatile contaminants at sub-atmospheric pressures while the oil is maintained in the form of finely dispersed particles in a vessel, the walls of which are heated to prevent condensation of the vaporized volatile contaminants within the vessel.

Another object is to supply sufficient additional heat to a previously heated contaminated oil while being distilled at sub-atrnospheric pressures and while in a finely dispersed state to obtain complete vaporization of all volatile contaminants and to prevent condensation of the vaporized volatile contaminants within the distillation chamber.

Another object is to supply sufficient addi tional heat to a contaminated oil which has been heated immediately previous to introduction to a distillation chamber in a finely dispersed state, the chamber being maintained at sub-atmospheric pressures to remove volatile contaminants in a vaporized form and to prevent condensation of the volatile contaminants within the chamber.

Another object of our invention is to remove light volatile contaminants from an oil by subjecting the contaminated oil in a finely dispersed form to a sub-atmospheric pressure at a temperature substantially below the flash point of the original oil before contamination.

Another object is to remove volatile contaminants from a contaminated oil by subjecting the contaminated oil in a finely dispersed form to the action of a sweeping agent at a sub-atmospheric pressure and at relatively low temperatures, that is, temperatures substantially below the normal boiling point of thehighest boiling volatile contaminant.

A further object is to provide means for removing volatile contaminants from a contaminated oil by introducing a sweeping agent into the contaminated oil and subjectingthe mixture of contaminated oil and sweeping agent to a subatmospheric pressure and at a relatively low temperature while the contaminated oil is in a finely dispersed form.

Another object is to remove volatile contaminants from a contaminated oil by introducing a sweeping agent into the oil, and spraying the mixture of contaminated oil and sweeping agent into a vessel maintained at a sub-atmospheric pressure to remove the volatile contaminants and the sweeping agent in the vapor phase, to recover the oil freed from its volatile contaminants.

Another object is to remove volatile contaminants from a contaminated oil by exposing the oil in a finely dispersed form at'a temperature substantially lower than the flash point of the original oil before contamination to a sub-atmospheric. pressure in a vessel, the walls of which are maintained at a temperature substantially at least as high as the temperature of the oil being treated in it.

Still another object is to provide means for removing volatile contaminants from a contaminated oil by exposing it to the combined action of a sweeping agent and a sub-atmospheric pressure while the contaminated oil is in a finely dispersed form in a vessel, the walls of which are maintained at a temperature substantially at least as high asthe temperature of the oil, being introduced into it., j v

Other objects and a fuller understanding: of our ,of undesirable low boiling contaminants 4 invention may be had by referring to the following description and claims, taken in conjunction with the accompanying drawing, in which:

Figure 1 is a cross-sectional view of an apparatus embodying the features of our invention and capable of carrying out our process;

Figure 2 is a modification of Figure 1, in that an arrangement for adding a sweeping agent is added to the equipment; and

- Figure 3 is a further modification wherein the spray means for the sweeping agent surrounds the spray means for the oil.

To achieve separation of volatile contaminants from a petroleum oil, it is necessary to use some convenient form of distillation, and all known methods of re-refining oils contemplate the use of this type of physical action. Many means have been devised to accomplish this separation rapidly, completely, and efficiently, but all have comprehended the separation being done by distillation of considerable quantities of the contaminated oil. Consequently, an appreciable time interval elapses between the introduction of heat and pressure change and completion of the removal of the volatile contaminants, and to accomplish final removal of the last traces of volatile contaminant from a quantity of oil, thermal energy is applied at an increasing rate. While this is being done, conditions exist in the oil frequently favorable to breakdown of some of the normal constituents, with formation of additional products of lower molecular weight, and consequently of lower boiling point, usually sufiicient in degree and amount to cause them also to be classified as volatile contaminants, and contaminants which should therefore also be removed. Before a completely desirable result is achieved it is frequently found that the final yield of oil freed from its volatile contaminants has been unsatisfactory from an economical standpoint. If the distillation be not carried on with this degree of thoroughness, the presence of constant boiling mixtures will frequentlycause'the final product to be considered not totally satisfactory in regard to flash point,

the characteristic most usually employed in evaluating the freedom or otherwise of an oil from low boiling components. This inturn is considered to be indicative qualitatively of increased con sumption in service.

If, however, a comparatively small amount of oil be subjected to a distillation proces as described at sub-atmospheric pressure, and if this quantity be extendedto present the greatest possible surface to this action, it is found that the removal is achieved with a degree of completeness not previously possible, and in a period of time which does not permit any observable degradation of the normal constituents of the oil. In order to present maximum surface, it is necessary either to present a continuous film of negligible thickness, or to disperse the oil in exceedingly fine globules The existence of either of these forms must persist for a period of time sufficient to assure the removal in vapor form of the low boiling point impurities. From the standpoint of control of operating conditions, it has been found to be more satisfactory to present discrete globular particles to the combined action of heat and reduced pressure than to extend a continuous film, only one surface of which can be presented to the sub-atmospheric pressures and spaces.

One of the features of our invention is the provision of heat for the walls of the chamber independently of the heating of the contaminated 7, at temperatures very substantially lower than those which are necessary when batch vacuum distillation is used and which are below the critical temperatures for thermal decomposition. Thus,- we have found that diluents which had been introduced into aircraft engine oils in service to the extent of approximately six per cent of the total volume, and which consisted of volatile hydrocarbons, such as are present in gasoline, together with some low molecular weight oxidation products and water were apparently totally removed by spraying the contaminated oil which had previously been heated: to 300 F; into the distillation chamber, which was maintained at a vacuum of approximately 29.6 inches of mercury as referred to a 30-inch barometer,v the walls of the chamber also being maintained at 300 F. r

The flash point of the aircraft engine oil was 480 F. when new and the contaminated oil contained a sufficiently high proportion of very volatile hydrocarbons that the flash point was approximately 115 F., and sustained combustion occurred at 155 F. After subjecting the contaminated oil to the process described above, the product had a flash point of 495F. Similarly, the viscosity of the contaminated oil was very much less than that of the new oil, while the viscosity of the product after treatment was substantially identical with that of the new oil.

Determination of the value for the physical properties usually accepted for evaluation of an oil showed that after the contaminated oil had been fractionally distilled by the process which we have discovered, .the product met the requirements outlined in the specifications for new aircraft oil.

A series of experiments was made with the same aircraft engine oil in which sweeping agents were used, and in which the direction in which the oil was caused to travel after introduction into the distillation chamber was changed, to determine if changes in the path of travel of the finely dispersed particles in relation to the liquid outlet and the vapor outlet were significant. We have discovered that no appreciable differences were obtained, the flnal product in every case possessing physical properties closely paralleling those demanded for new oil. 1.

While these results show that the limiting conditions for removal of volatile contaminants had been met in every case, to extend theresults in the general field of'oil contamination, particularly petroleum oil contamination, series of tests were made with an electrical oil, specifically a transformer oil, and with an oil used in the heat treatment of steel.

In the case of the contaminated transformer oil, it was found that the oil before treatment was dark in color, possessed a neutralization value of 0.53 milligram KO-I-I per gram of oil, and a dielectric strength of '7 kilovolts when tested by the standard method of test described by the g A. S. T. M. Some .sludgev was present, and the this treats ment was then analyzed and the neutralization value was found to be 0.21 mg. KOH per gram of oil, the moisture content was nil by the same method of distillation from xylene, and the dielectric strength'was 24 kilovolts. In addition, the product was substantially lighter in color than the contaminated oil before treatment.

The utilization of the process had therefore resulted in the elimination of water and in reduction of the neutralization value of the oil,-

which can only be ascribed to removal of volatile oxidation products such as carboxylic acids and esters, compounds which are sufficiently active, in a chemical sense, to cause deterioration of the equipment in which'they may'come in contact. The increase in dielectric strength 'is likewise ascribed to removal of these volatile contaminants, since it is well known that mechanical dispersions of water and the presence in solution of substances relatively rich in oxygen will materially decrease the eiliciency of transformer oils and of hydrocarbon dielectrics in general.

With regard to the oil which was used for the heat treatment of steel, it .had been discovered in the commercial application for industrial production, that after a certain degree of contaminationhadoccurred, the rate of heat dissipation had been accelerated to the point where surface hardening or brinelling was prevalent, and persisted to an extent which either militated against subsequent machine finishing operations, or resulted in the rejection of the steel, because of failure to meet manufacturing specifications.

The rate of heat transfer is analogous to the rate of transfer of electrical energy in that the same contaminants, and degree of concentration of these contaminants, will affect these properties in like manner, although there may be a difference in the final permissible limits.

The heat transfer oil,;or quenching oil, which Was used for the experiments herein described, had been rejected as unfit for further use in industry. On analysis, it was found'to contain a' small amount of free water, and the neutralization-value was very much higher than that of the oil originally.

This contaminated oil was heated to a temperature of approximately 250 F., and sprayed into the evacuated distillation chamber, the

:walls of which were maintained at substantially the sametemperature as the oil being treated, and the volatile contaminants vaporized and removed in the vapor form. In some of the experiments, steam Was used as a sweeping agent,

and itwas found that by the use of this sweeping agent, the rate of treatment could be increased to some extent without deleteriously affecting thequality of the treated oil. In all cases, it was possible to produce an oil which possessed physical properties equal to or approximating those demanded in purchase specifications for new'oil for the designed application. More significantly, when oil which had been contaminated in service and subsequently subjected to our process as described above was replaced into commercial use, it was found to function in a completely satisfactory manner. While the scientific study of service contamination of quenching oils is not nearly as complete or thorough as, similar studies made for electrical and lubricating oil deterioration, a broad survey of the results so far available shows that the progressive formation or incidence of volatile oxidation products and of Water, and of extraneously introduced contaminates or catalysts for the stantialn rtio i modueti ncostsiom ptedu tiorieot:coniamin t nsmro ucts mealtime parallel deterionati nlafle ne th sue- ,meta productsltreated th reincandethetia; lim cached.imaeomaratmem Short cost oflrenlacement,th retore. cont ibute a sube metal mmductswhichrhaveto esubie t dtolthisltreat- ,menteg when means for; treating suchloi s-iby; o

upr cess arer vidediing' oniunction withithe h at" t eatin ;,bath,--the;ilifeeoftthe eatltransienmeadmin hassheen prol nged-to,-aeperiodeexceeding zeser ral times :that: iofdmediumsmsed. in identical a pl at ns dh tnwhere theatre -.heen mad'eavailable: q .-m.ayethe 0. eibe,statedithat; app icati ns, ;.:hydrocarbonteeilsamtapredomiina t y -.p tro emn originsthe :u1 .a1l.,i fe,i0f ,sueh soil iv rie idirectly-with the raters-accumulation f:;servi. centaminantsaandathatea seriousipro- ,p tion cof, these, ont -minantsuarie productsliof atmentu hasanot ta W e n -'1 e k e l We filesmfib a ur ntion-with a 'ce-rtairf deg stood that the p only by way of eXarnple,,:-.and that numerous chanfge's {in the details.,;ofi-; constructioncandil the combination and arrangement of parts may be resorted to without departing from the spirit and the scope of the invention as hereinafter claimed.

We claim as our invention:

1. Apparatus for treating oil comprising, a vessel, means for evacuating the vessel, spray means for spraying the oil in the vessel, a container having a heat transfer liquid, means for heating the said liquid, conduit means for conveying the oil to the spray means, said conduit means and said vessel being immersed in the said heat transfer liquid.

2. Apparatus for treating oil comprising, a vessel, means for evacuating the vessel, spray means for spraying the oil in the vessel, a container having a heat transfer liquid, means for heating the said liquid, conduit means for conveying the oil to the spray means, said conduit means and said vessel being immersed in the said heat transfer liquid, and second conduit means including a nozzle for introducing a sweeping agent in the vessel, and means for heating the second conduit means by the heat transfer liquid.

3. Apparatus for treating oil comprising, a vessel, means for evacuating the vessel, spray means for spraying the oil in the vessel, a container having a heat transfer liquid, means for heating nterrupti for ,oreduction an greatly afmammal -lea- ,ithesaid; liquid conduit means for, conveying the .0il-,-to ,the spray, means, saiduconduitgmearis and saidlvesselheing immersedin thels'aid heat='trans- ,uler. liquid, fiHCILSEQODdMCOIidUitQ means' including I a nozzle tor -.-intro'ducing,;-. a ,sweeping; agent I i'in'l the Messel and means for. heating the second conduit means by the ,heat jtransf er liquid, said sweeping eagentenozzleisurroundingcsaid spray :means' and reintroducing the;,sweeping;,agent inztheoilspray.

,.4.,'iI he1process ,iOrtreating.;oi1;comprisingithe cstepslofrlleating and sprayingsame into an evac- .a tedlcha rnber;,while,,.the said chamber is,-'sub- .tstantially completely s rounded in albedy f h at, transiereflui'd, which, heats .andmaintai'ns .15 55 1. chamber toaat; leastgthe, boilingzxpoint jtemtl lellatll el lofstheeimpllrityr. toabe removed having the highest,boilin zpoint temperature at, the. pres- 5111 fethe .eYaQuated. Vessel, andyremovingihe .yo zedimpurities, and drawingnthe treatedloil 7,1 0E mmit eiehamber.

DD rntreating i, oil, eicomprising ca first-clo ed. :vesse1, asecond, closed zvessel' posiiionedgyvithinihefirst vVesselto.loroviclesspace .be-

, tw eemthen terior surface of.,the; .first yessekand the,-,e 5terior,; surface.;,oi,rthev second vesseL. and marine; che t. ltransfer medium..: between said faces, ;,spray,.;means ,ior .sprayingthe. oil iin th second elosedvesselsfirstconduitmeans-for me ing t tofl to :t snraycmeans, throu hfi tz ansfer;;medium, said conduitmeans 1 6 b tween other first clo'se'd; vessel on ieclosedw,vessel,, second conduit i beinerosit qnedbetweent e fir and sed ,vessel s;,,;means iior heating; the. heat e. rsmedium;,tocsupp ylheat to,,..the..w,alls of e; second,closedvessehand ,to .thesaidfirst-and iseqmdcondu t-me ns means; forlevacuatingith M V, v I ed, -yes s el,;and conduit means for. .r'e-

moving h treated, oilzjfrom,the-secondecl0sed Apparatus, fo ll lfi ttingnoil, comprisin a d vessel, alsecondlclosed v.vesseijrpos fir tet ss lto providetspac i resurfa eh f fthefirst evessel .urfa e.. f these eccnd. vessel; and

s rm iumbetweensaidsurtiaee msnra means; .iers raymg ,fthei,oil.-in, ,the second closed vessel, first conduit means for conveying the oil to the spray means through said heat transfer medium, said conduitmeans be ing positioned between the first closed Vessel and the second closed vessel, second conduit means including a nozzle for introducing a sweeping agent, said second conduit being positioned between the first and second closed vessels, said sweeping agent nozzle surrounding said spray means and introducing the sweeping agent in the oil spray, means for heating the heat transfer medium to supply heat to the walls of the sec- 0nd closed vessel and to the said first and second conduit means, means for evacuating the second closed vessel and conduit means for removing the treated oil from the second vessel.

7. The process of treating oil having volatile constituents therein, comprising the steps of heating the oil, thereafter atomizing the oil to produce a mist atmosphere of the oil and volatile constituents by spraying the oil in an evacuated chamber, said chamber having chamber wall surfaces toward which the spray is directed, and supplying heat energy to substantially all of the wall surfaces of the chamber independently of the heating of the oil to be treated to substantially maintain said chamber wall surfaces at a temperature at least as high as the boiling point,

' 11 at the reduced pressure of the evacuated vessel, of. the highest boiling point constituent to be removed, and'removing the volatilizedco'nstituents and the treated oil through difierent outlets.

8. The process of treating oil having volatile constituents therein,'-comprising the steps of heatingthe oil, thereafter atomizing the oil to produce a mist atmosphere of the oil and volatile constituents by putting the heated oil under pressure and spraying the oil in an evacuated chamber, said chamber having chamber wall surfaces toward which the spray is directed, and supplying heat energy to substantially all of the wall surfacesOI' the .chamber independently of the heating of the oil to be treated to substantially maintain said chamber Wall surfaces at a temperature at least as high as the boiling point, at the reduced pressure of the evacuated vessel, of the highest boiling point constituent to be removed, and removing the volatilized constituents and the treated oil through different outlets.

9. The process of treating oil to remove volatile.

constituents contained therein, comprising the steps of putting the oil under a pressure of more than at least one atmosphere, thereafter spraying said oil into a chamber maintained at a pressure of at least less than one atmosphere, said chamber having'chamber wall surfaces toward which the spray is directed, said at least less than one atmosphere of pressure being a composite pressure of the partial pressures of at least one other gas besides the volatilized constituents of the said oil, and supplying heat energy to substantially all of the chamber wall surfaces to substantially maintain said chamber wall surfaces at a tem-- perature at least as high as the volatilizingtemperature of the constituent to be removedfrom the oil havin the highest boiling point'in the partial pressure credited to saidconstituent.

10. The process of treating oil having volatile" constituents therein, comprising the steps of heating the oil, thereafter spray atomizing the oil in an evacuated chamber to produce a mist atmosphere of the oil and volatile'constituents, and supplying thermal energy to substantially all of the wall surfaces of the chamber independently of the heating of the oil to be treated to substantially 1'12 maintain said chamber wall surfaces at a temperature at least as high as the boiling point, at

the reduced pressure'of the evacuated vessel, of

the 1 highest boiling point constituent to be removed, and removing the volatilizedc'onstituent and treated oil through different outlets.

11. Apparatus for treating oil, comprising a first closed vessel, aps'econd closed vessel positioned within the first vessel to provide space between the interior surface of the first vessel and the exterior surface of the second" vessel, and means to provide heat 'between said surfaces, spray means for spraying the oil in the second closed vessel, conduit means for conveying the oil to the spray means, said conduit means bein positioned between the first closed vessel and the secondclosed vessel, said means for providing heat between said surfaces serving to supply heat both to the walls of the second closed vessel and to the said conduit means, means for evacuating the second closed vessel and conduit means for removing the treated oil from the second closed vessel.

' 1 CHARLES J. EGGER.

ROBERT I-I. WEBSTER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number 524,209 Great Britain Aug.1,1940