US2443970A - Refining of lubricating oils - Google Patents

Description

June 22, 1948. P. M. wADDlLL REFINING OF' LUBRICATING OILS 2 Sheets-sneer 1 Filed Jan. 3, 1944 INVENToR June Z2, 1948. P. M. wuaDlLl.v

REFINING 0F LUBRICATING GILS Filed Jan. 3, 1944 2 Sheets-Sheet 2 INVENTOR P. M. WADDILL Patentedl `lune 22, 1948 Sy PATENT ori-'ica j REFINING oF LUBRIcA'rJINGoms: f Paul M. Waddill, Bartlesville, Okla., assignor to Phillips Petroleum Company, a corporation ofv Delaware Application January 3,1944, Serial No.` 516,894 3 claims. (ci. 19e-17) This invention relates to a method for distilling oils and more particularly it relates to a method for the vacuum distillation of lubricating oils.

The conventional rectification or fractionation tower, in which .vapor is fractionatedl by repeated countercurrent contacts with liquid reflux, usually the color and color stability are markedly imimposes an appreciable back pressure on the source of the vapor. Inorder to maintain constant or uniform flow through a given fractionator acertain minimum inlet pressure must be maintained. This pressure', of course, depends upon many factors, such as the number of trays, the tower throughput, outlet pressure, and others. Appreoiable reflux liquid is carried on each tray and a certain pressure frequently as high as one half pound or even more per square inch per tray ,is consumed in forcing the upward ilow of the vapors being fractionated. Thus a 30 tray tower may consume approximately 1 atmosphere of pressure, and in view of this consideration, one atmosphere of vacuum on a fractionator outlet will be fully dissipated at the fractionator inlet. Thus, the futility of bubble tray fractionation in high vacuum systems is obvious.

Lubricating oil types of hydrocarbons have very high boiling points, -so high, in fact, that such oils frequently cannot be distilled without decomposition. By the use of steam, the distillation te'mperature of some lubricating oils can be lowered sufficiently to avoid thermal decomposition. Large amounts .of steam are required in such distillation hence steam costs are high. In addition, the steam distilled oils must be separated from the condensed steam and dried before marketing. Thus, vacuum distillation in some form offers many advantages over steam methods. Some refiners use combined steam-vacuum processes, and such methods offer definite advantage over` the use of steam alone.

I have found 'a method of heavy oil distillation wherein vacuum alone is used, and my DIOCESS has many advantages over processes in which "steam is used.

O'ne object of .my invention is to provide a lubricating oil distillation method.

Another object of my invention is to provide a method of lubricating oil distillation by vacuum and in the absence of steam.

Still another object of my invention is to provide a process for the fractionation of lubricating oil stocks by vaporization under high'vacuum in the absence'of steam followed byfractional condensation of the vapors.

Yet another object of my invention is to provide a process for the separation of neutral oils from bright stocks by lvacuum distillation wherein proved, which advantage is reflected in 'considerable saving in decolorizing clay costs.

Still other objects and advantages. will be apparent to those skilled in the art from a careful study of the following disclosure, which in conjunction withthe attached drawing, forms a part of this specification.

Figure 1 shows, diagrammatically, one form of apparatus in which. the process of my invention may be practiced, and

Figure 2 shows, diagrammatically, another form of apparatus in which the process of my invention may be carried out.

Ordinary, commercially available vacuum producing steam jets do not give sufficient vacuum for best lubricating oil distillation. I have found that neutral oils condensed in the chambers of my apparatus make excellent circulating media, and when used with properly designed vacuum producing jets, very lcw vacua can be produced. In apreferred embodiment of my invention, I use .the conventional 3--stage steam jet to obtain a vacuum of approximately 757 millimeters of mercury, that is, a residual absolute pressure of 3 millimeters of mercury, and supplement this with a series of properly ldesigned oil operated jets wherein pressures of l, millimeter of mercury or lower can be obtained. I have found that by using pressures as low as 1/6 to 1/10 millimeter that neutral oil constituents can be distilled from bright stocks at a temperature sufficiently low as to avoid much of the thermal decomposition `or color formation usually obtained when lthe distillation is obtained at higher pressures.

' vacuum chamber vaporizatlon, the lower boiling hydrocarbon con- V 3 v sented by numerals I4, 23, 35, 46 and 14, by partitiOnS 56, 51, 58 and 59. Partitions 55, 51 and 58 carry Venturi jets I3, 34 andv 45, respectively.

These jets are the above referred to jets, which are operated by condensed oils." Each compartment is equipped with'a liquid level controller,

as represented by numerals I8, 25, 31, 48 and 68, which are intended to controlthe amount of liquid in the respective chambers, the liquid in the said chambers being identified by numerals I1, 24, 36, 41 and 6I. .y

In the operation of the process, when using the apparatus represented in'Figure 1, longresiduum D bright stock from a bright stock still, not shown, passes through line II, a heat transfer means I2 in which the oil stock is heated or cooled, as required, through a spray nozzle I into the compartment I4, which is the rst of the series. A iinal vapor outlet 13 is connected to a 3-st`age steamoperated vacuum producing jet, not shown. This jet produces a vacuum of the order of 3 mm. absolute pressure which is communicated to the final chambers 14 and 46. The oil jet 45 oper ating to reduce'the pressure in compartment 35 to' approximately l mm. residual pressure dis` charges into the compartment 46. Similarly, oil jet 34, taires suction on compartment 23 andreduces the pressure therein to about 1/3 mm., while the oil jet I3 reduces the pressure in compartment I4 to the very low pressure of about 'l/t millimeter of mercury. The above mentioned bright stock feed at a temperature of approximately 500u to 700 F. is fed into said compartment I4 through spray nozzle I5. The oil at the temperature of 500 to 700 upon being sprayedinto the high I4 undergoes considerable 'stituents being vaporized. These lower boiling hydrocarbon constitutents are the type ofv oily Vcompounds normally contained in theso'called "neutral oils. While the neutral oil hydrocarbons vaporize under these conditions, the higher molecular weight, higher boiling hydrocarbons remain as a liquid and settle tothe bottom of this chamber and remain as liquid I1. This liquid, termed D bright stock, is discharged through a line 22, cooled in'a cooler I9, the ow being controlled by a pump 20 and a valve 2I, the operation of the latter being controlled by the liquid level controller I8. The stock passes from line 22 to a storage vessel, not shown. This stock is of good color, good color vstability and of generally excellent quality, since the oil has been maintained at a relatively low distillation temperature for a veryshort period of time.

Since the charge oil is sprayed by nozzlev I5 at a high velocity a splash plate or vbailie I6 is necesy valve 3I compartment 23, the circulating liquid oil settling as liquid along with additional condensate oil. A baille plate 26 prevents the high velocity disk charge from jet I3 from interfering with the operation of jet assembly 34. Excess liquid condensate not needed for the effective operation of Venturi-jet I3 operatesv the liquid level controller device 25,which in turn opens an outlet and permits removal `of condensate through a line 32 to individual condensate storage, not shown, or through a manifold line 58 containing valves 33, 15 and 16 and a line 61 to a composite neutral oil storage, not shown.

The oil vapors not condensed by compression from 1,6 mm. to 1A; mm. in chamber 23 are further compressed toabout 1 mm. pressure von passage through Venturi jet 34 into compartment 36. Compartment 35 operatesin a manner similar to that of compartment 23, that is, -by an increase of pressure and a decrease of temperature to. say, about 300 to' 400 F. Condensate oil passes through a line 39 and is pumped by a pump 4B through an exchanger 4I, a line `42 to the nozzle or jet of venturi 34. A baille 38 prevents liquid oil being carried into the next successive chamber 46. Excess condensate oil not needed for the operation of the venturi 34 and accumulating ,inl chamber 35 is removed therefroml through the and 16 and line 61 to composite neutral oil storage, n

not shown.

In a similar manner compartment 46 operates. The pressure is raised therein to 'about 3 mm. mercury pressure by Venturi jet 45, while the temperature is lowered to from approximately 150 to 250 F., and the condensate thus produced is used for the operation o the jet by passage through aline L5I), a pump 5I, an exchanger 52 and a line 53 to the jet. Excess oil accumulating in this chamber is removed by the operation of liquid level controller mechanism 48 and an outlet valve 54. Excess condensate oil may pass to individual storage, not shown, through a line 55 or through a line 68, valve 16 y and line 61 to composite neutral oil storage, not

of mercury, and the pressure in compartment 23 is about 1A, mm. This latter pressure is higher than the $6 millimeterfand amounts to compression, thus the highest boiling constituents of the vapors entering compartment 23 are condensed by compression and temperature reduction since temperature therein is maintained at about 400 to 600 F. Condensate formed therein settles to form the liquid 24. This liquid is withdrawn by a pump 28 through a line 21, a cooler 29 and passes through a line 30 to operate the said oil jet I3 which assists in evacuation of chamber I4. The oil with the entrained vapors'issuing from the Venturi-jet assembly I3 discharge into the shown. A splashplate 49 prevents liquid oil from jet 45 from passing into the final spray compartment 14.

Oil vapors, uncondensed in compartment 46, pass between baille plate 49 and partition plate 59 into spray compartment 14 in whichl most or substantially all of the remaining oil vapors are removed by absorption in oil issuing from sprays 69.- Excess oil accumulating in this scrubbing chamber is removed through the operation of a valve 86, which is actuated by the float controller mechanism 68, the oil passing through a line 62. a pump 63, a heat exchanger 64, the said valve 66 and line 61 neutral oil storage, not shown, while the main volume of the oil is continuously circulated through line 62 and a line 65 which latter leads directly tothe scrubbing sprays.

The temperature of oil spray 89 is adjusted` by heat exchanger 64 to cause. condensation of ythe desired neutral oil in chamber 11 and yet permit the undesired water vapor and light hydrocarbon vapor traces to be ejected through line 18.

A partition plate 1| contains a mist remover 1l for removal of oil mist which fails to settle in chamber 14. A small opening 12 permits liquid accumulating in a small chamber 11 free access to the spray chamber from which it may be removed as explained hereinbefore.

In summarizing the above detailed operation it might be mentioned that in normal operation the amount of bright stock oil remaining in the ilrst of the sequence of chambers is relatively large, while the several intermediate fractions accumulating in chambers 23, 35 and 48 are relatively small in'volume. `The output from the scrubbing compartment constitutes by far the l major portion of the neutral oil production.

The several heat exchange means mentioned above may be used as heaters, or coolers, or some as heaters and the remaining as coolers, all depending upon the particular operation desired. For example, exchanger |2 may operate as a heater to impart to the feed stock sufcient sensible heat to evaporate all of a desired portion of the oil on passage through sprayer I5 into the,

vacuum compartment I4. yIn case the said` feed stock comes from a still tower or other apparatus employing a relatively high temperature, the temperature of the oil may be such that heater I2 may not be needed, in which case it may be bypassed or said apparatus may serve to cool the feed oil in case temperature-is higher than desired. Similarly, the several heat exchange means 29, 4|, 52 and 84 may be operated in a manner as dictated by the product desired from each of the respective chambers. These heat exchange means are, of course, operated in cooperation with the degree of vacuum in said respective chambers, as will be understood by those skilled in the vacuum distillation art. For example, a light neutral oil may be produced in the scrubber chamber, while a neutral oil having a slightlyv greater viscosity will come from the next successive chamber 46. A still more viscous oil will come from chamber 35 while the most viscous of the oils vaporized in .vaporizing chamber I4 will be produced in chamber 23. The relatively heavy bright stock will be removed from the vaporizer chamber I4. The apparatus may be s0 operated as to produce oils having substantially S. A. E. vlscosities, 'for example, neutral oil being produced in spray chamber 14, S. A. E. in chamber 45, S. A. E. 20 in chamber 85, and S. A. E. 30 in chamber 23. My process, as mentioned, is variable in nature, and with the proper design and construction of the apparatus many products of good quality can be made. It might be mentioned that the drawings are merely diagrammatic in form, as for example, the size and number of chambers. The chambers even need not be the same size, but may be made in approximate proportion to relative amount of each fraction to be removed. The amount or volume of oil carried in the sump portion of each chamber may be at least somewhat separate and independent vessels while in Figure 1 the chambers are portions or compartments of one large vessel.

mercury absolute pressure.

In the operation of the process when using the apparatus illustrated in, Figure 2, the long reslduum bright stock enters the apparatus by Way of aline having been previously heated in a still or heater, not shown. At the proper temperature the charge oil enters a vessel 81 through a spraynozzle 8|. Sufficient sensible heat contained in the oil causes the desired amount of distillation as the oil is sprayed into the vacuum of said vessel 81, `for example, 1/n 'millimeter of The residual, unevaporated oil accumulates in the bottom of said distillation vessel, the level of which oil is represented by numeral 82, and is controlled by a liquid level control apparatus 83 which operates to openand close a valve 84 for discharge of the accumulated oil 82, for example, a. D bright stock oil, as mentioned hereinbefore. This oil is prefer-ably cooled in a cooler 96. on passage through a line 85 on its way to storage, not shown.

The distilled oil `vapors originating in vesselv 81 are removed therefrom by passage through a Venturi'jet 86. This jet maintains the above `'mentioned 1/9` mm. pressure in vessel 81 by discharge into a next successive vessel 88 in which a total pressure of about 1/3 mm. may exist.` At this greater pressure some condensation of vapors occurs yielding a condensed, liquid, neutral type oil, represented by numeral 89. This condensate oil is withdrawn through a line 92 by a pump 93, heated or cooled as required by a means 94 and transferred through a line 95 to Venturi jet 88 for its operation. The excess liquid accumulated in vessel 88 and not needed for the operation of venturi 86 is removed through line 92, a manifold line 91 through a valve 98, the operation of which is actuated by a oat controller device disposed in vessel 88. This excess oil or make may be removedl from the system through an individual productv line 99 or passed on through manifold lines |00, |23 and |34 to storage, not shown. A baille plate 9| prevents liquid passing from vessel 89 through the vapor line to the next successive vacuum jet.

A next vessel, in sequence, |02, is operated by a venturi |0| maintaining a'pressure of approximately l mm. which pressure is a-threefold increase and causes condensation of another fraction of neutral oil from ther vapors from the previous vessel 88. Condensate |04 accumulates, a portion being recirculated through a line |08,

by a'pump |01, and through a. line ||0 for the manifold line |00, lines |23 and |34 to composite neutral oil storage, not shown, as desired. A baille plate |03 prevents exit of liquid oil through the vapor line to the next successive vessel.

The vapors issuing from vessel|02 pass through another venturi I2 and are discharged therefrom into a vacuum vessel ||3 at a higher pressure of -about 3 mm. and at this pressure additional liquid oilris condensed. This oil identified by numeral ||5 is used for vacuum producing purposes by circulation through a line H1, by a pump H8, through a heat exchanger H9 and von through a line to the jet ||2. Excess oil not needed for vacuumproducing purposes passes v from line Ill through avalve |2| and a neutral oil line |22 to individual storage, not shown, or

may be passed through valve |2l, lines |23 and |34 to composite storage, also not shown. A float controller device ||6 operates to control the opening and closing ofvalvek |2|. A splash plate |I4 prevents liquid passing from vessel |13 through 1a vapor line |24 to a next successive vessel |25.

. In the nal vessel is mounted a liquid spray device |26 for extracting oily constituents from the residual vapors entering from vapor line |24. The absorption oil or washing oil as it-may be termed, is the extracted oil itself, the washing cycle being passage of the oil represented by numeral |21 through a line |3| by a pump |32,

. through an exchanger |33 on to the spray nozzles |26. The oil not needed for circulating is withdrawn from the vessel by operation of a float controller |29 which actuates a valve Hillv permitting the said oil to pass through line |3I, pump |32 and line |34 to a neutral oil storage which is not shown in the drawing. A baie plate |28 prevents passage of mist, etc., through a final suction line |35 to a primary 3-stage steam vacuum jet apparatus, not shown.

The distillation temperatures held Within the several vacuum chambers of Figure 2 may be substantially those given in connection with the discussion of Figure 1, or may be varied to meet the conditions presented by a given oil stock.

This second apparatus embodiment, as mentioned hereinbefore, operates substantially as doesthe apparatus of Figure 1. Exact operating temperatures and pressures will be determined at least in part by the type of feed stock to be processed, the grade of oils to be evaporated and subsequently condensed in each stage and other factors too numerous -to mention, all of which are readily understood by one versed in the vacuum distillation art.

The oils produced herein are of good color and -good color stability on account of the relatively low distillation temperatures possible and the low distillation temperatures are possible because of the use of the oil operated vacuum jets. The production of the oils with good color characteristics markedly decreases clay decolorizing costs, and these costs in conventional high temperature operations are high.

It might also be mentioned that the process steps may be easily operated and controlled since each vacuum jet operates independently of the valuable and herein is one important advantage of my process.

For .purposes of simplicity many valves, automatic controlling devices, etc., have been omitted from the iigures and from the descriptions. This apparatus is of standard design and readily obtainable from manufacturers,v and the operation of which is understood by those skilled in the oil refining art.

This second embodiment of apparatus (Figure V2) maybe used to produce a D bright stock and a series of neutral oils, or a bright stock and series of oils of standard S. A. E. viscosities, as well as is the apparatus of Figure l. All product streams from either apparatus will be bright"`since they are produced under high vacuum and low temperatures such as 50W-700 F. for compartments I4 and 81 of Figures l and 2, respectively, temperatures of 400-60 F. for the next successive compartment in each figure, while the third compartment of each may operate at temperatures as low as 300-500 F. The final washing compartments operate at about 150- 250? F. It willbe readily appreciated by those skilled in the art that these said temperatures are exceptionally low for lubricating oil distillation operations.

My process is not intended to be limited to the distillation of lubricating oil but may be applied to the distillation of any oil or oil stock wherein vacuum or vacuum and steam distillation are ad-4 vantageous.

I claim:

`1. A process for the'subatmospheric distillation of lubricating oil stocks, comprising discharging the lubricating oil stock in aheated condition into the rst of a series of serially connected containers the interior of which is maintained at subatmospheric pressure to vap-orize a portion thereof, the liquid residue therein forming one product of the process, discharging the vapor portion into the next container to condense a portion thereof,- causing discharge of the vapor into the second container by aspirating it by a portion of the condensate of that container, progressively introducing the vapor fraction in each container into the succeeding container byv aspiration with a part of the liquid portion of the succeeding container, and withdrawing the liquid portions from each container as products of the process, the vaporl portion discharged into each container being discharged into the space thereof above the collected liquid condensate therein.

2. A distillation apparatus of the type described comprising a plurality of containers forming isolated spaces, injector connections for connecting said containers in series, means for main- .taining an all over subatmospheric condition in said spaces, means for discharging a heated lubricating oil stock into the lrst of said spaces and connections from each of several of said spaces to the injector discharging thereinto for delivering a portion of the condensate of the space to the injector, each injector discharging the vapors of one associated space into the other associated space at a higher pressure, and means for withdrawing the condensates injected in each container therefrom as .products of the process, said injectors discharging into the spaces above the condensate bodies collected therein.

3. An apparatus of the character described comprising'in combination ka series of at least three chambers, said chambers being adapted to contain liquids and vapors, each of said chambers having a liquid outlet, means connecting said chambers in series for vapor transfer consisting of liquid actuated vapor injectors, each of said injectors providing a vapor outlet for the first of said chambers and a vapor inlet for the REFERENCES CITED The following references are of record in the file of this patent:

Number y 10 UNITED STATES PATENTS Name Date Forward Apr. 8, 1919 Isom et al Oct. 27, 1925 Isom et al. Feb. 16, 1926 Subkow July 22, 1930 Halle Apr, 5, 1932 Subkow Apr. 12, 1932 Subkow June 7, 1932 'Erving et al Apr. 18; 1933 Youker Aug. 2, 1938 Rude Mar. 28, 1939 Schulze et al. Oct. 8, 1940

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