US2110845A - Treatment of heavy hydrocarbon oils with light hydrocarbons - Google Patents

Description

J. M. WHITELEY ET AL ,110,845

March 8, 1938.

TREATMENT OF HEAVY HYDROCARBON OILS WITH LIGHT HYDROCARBONS Original Filed May 23, 1932 4 Shets-$heet l March 8, 1938. J. M. WHlT ELEY ET AL 2,110,845

TREATMENT OF HEAVY HYDROCARBON OILS WITH LIGHT HYDROCARBONS Original Filed May 25, 1932 4 Sheets-Sheet 2 March 8, 1938. J. M. WHITELEY ET AL 4 Sheets-Sheet 3 Original Filed May 25, 1952 x & Q 4 R h TREATMENT OF HEAVY HYDROGARBON OILS WITH LIGHT HYDROCARBONS March 8, 1938. J. M. WHITELEY ET AL v TREATMENT OF HEAVY HYDROCARBON OILS WITH LIGHT HYDROCARBONS Original Filed May 23, 1952 4 Sheets-Sheet 4 g 5w WK 5 k NR g H E Patented Mar. 8, 1938 PATENT OFFICE TREATMENT OF HEAVY HYDROCARBON OILS WITH LIGHT HYDBOCARBONS James M. Whiteley,

Roselle, and Gustav AlBeiswenger, Elizabeth, N. 1., assignors to Standard Oil Development Compan Delaware a corporation of Original application my 23, 1932, Serial No. 612,-

908. Divided and 9 Claim.

This invention relates to hydrocarbon oils, especially petroleum oils, and more particularly relates to the treatment of these oils with light hydrocarbons.

This application is a division of our copending application Serial Number 612,908 filed on May 23, 1932.

The term light hydrocarbons will be understood to mean hydrocarbons or mixtures of hydrocarbons of 1 to carbon atoms in a liquid or liquefied condition.

We have found that light hydrocarbons have, at high temperatures, say within 50 to 100 F. of their critical temperature, a marked selective action on hydrocarbon oils. We have also found that the selective action of these light hydrocarbons may be varied by changing the temperature at which they are used.

In the present invention the light hydrocarbon solvent may comprise either a .single light hydrocarbon or a mixture of light hydrocarbons and instead of changing the composition of the solvent to vary its selectivity, (in accordance with the method described by James M. Whiteley in United States Ser. No. 582,501 filed December 21, 1931) the temperature at which it is used may be changed and the composition may remain substantially constant.

The present invention therefore comprises the treatment of hydrocarbon oils with light hydrocarbon solvents either once at a constant high temperature whereby the oil is separated into two components of dissimilar characteristics, or repeatedly at a progressively changing high temperature whereby each component may be separated further into other components.

The method of carrying out these treatments with the light hydrocarbons will be fully understood from the following description read with reference to the accompanying drawings of which Figure 1 shows in sectional elevation a type of apparatus suitable for carrying out a single treatment at high temperature,

Figure 2 shows in sectional elevation a type of apparatus suited for a counter-current continuous treatment with a solvent of progressively changing temperature,

Figure 3 shows in sectional elevation a type of apparatus suited for an intermittent repeated extraction of the oil with a solvent of progressively changing temperature, and

Figure 4 shows in sectional elevation a type of apparatus suited for a counter-current treatment this application June 10, 1933, Serial No. 675,240

and forces it through line 4 into mixer 5, and

pump 6 draws solvent from tank 2 and forces it through line 1 also into mixer 5, wherein oil and solvent are thoroughly cornmingled. From mixer 5, the thoroughly mixed oil and solvent flow through line 8 into a heating means 9 wherein the mixture is raised to within 50 to 100 F. of the critical temperature of the light hydrocarbon solvent. Heat may be provided by steam, by heat exchange, or by other means. From heating means 9 the hot mixture flows through line I ll into a settling chamber ll provided with insulating means 12 and fitted with steam coils l3 whereby the required temperature can be maintained. The oil will separate into '2 through line I9 by pump l9a.

The light oil freed from solvent is withdrawn from still 15 through line 20 and may be passed to storage or to equipment for further treating.

The bottom layer in separating chamber II is withdrawn therefrom through line, 2| and passed into still 22 fitted with steam coil 23. The solvent vapors pass out of still 22 through line 24, pass through cooler 25 and the condensed solvent is returned to solvent supply tank 2 through line 19.

The heavy oil remaining in still 22 is withdrawn therefrom through line 26 and passed to storage or to equipment for further treating.

Referring to Figure 2, numeral 30 designates a storage supply tank for oil to be treated. Pump the oil; but if the oil is introduced into the middle of the tower the extraction will be carried out on both the light and the heavy fractions of the oil, the former with a solvent of progressively decreasing density and the latter with a solvent of progressively increasing density all as will be more fully explained below.

Tower 34 is an elongated vertical chamber which provides for counter-current fiow of oil and solvent. It may be packed with contacting means such as chain, jackstones, lumps of clay, or suitably designed plates, or may be without such contacting means. It may be provided with an insulating coating 31, and with heating means such as steam coils 38 placed at intervals along its length by means of which the temperature in the tower may be progressively increased from bottom to top.

Numeral 38 designates a storage supply tank for the light hydrocarbon solvent. Pump 48 draws solvent from tank 38 through line 4I and forces it through line 42 into the base of tower 34 into which it may be discharged through a suitable series of openings'indicated at 43.

In the tower the oil fiows downwardly in counter-current relation to the upwardly rising stream of solvent the temperature of which is progressively increased as it rises by means of steam coils 88. The oil is thereby separated into a lighter soluble fraction and a. heavier insoluble fraction. The former flows out of tower 34 through line 44 and discharges into a still 45 wherein the solvent is separated from the oil by distillation. Vapors of solvent pass out of still 45 through line 48, flow through cooler 41 wherein they are condensed, and the recovered solvent is returned by line ,48, pump 48 and line 58 to solvent storage tank 38.

The heavier fraction of the oil passes out of tower 34 through line SI and discharges into still 52 wherein the solvent is removed by distillation. Vapors of solvent pass out of still 52 through line 53, flow through cooler 54, and the condensed solvent returned to solvent supply tank 38 by lines 55 and 48, pump 48 and line 58.

Referring to Figure 3, numeral 88 designates a storage supply tank for oil to be treated. Pump 8| draws oil from tank 88 through line 82 and forces it through line 83 into a mixing device 84. Numeral 65 designates a solvent supply tank. Pump 86 withdraws solvent from tank 65 through line 81 and forces it through line 68 into mixing device 84 wherein oil and solvent are intimately commingled.

The mixture of oil and solvent then flows other hot gases. The heated mixture discharges into a settling chamber II fitted with an insulating coating 12 and a heating coil I3 wherein the mass is allowed to stand. The oil separates into two layers, the top layer containing the lighter fractions and the bottom layer the heavier.

The bottom layer is withdrawn from settling chamber II through line I4. It passes to a second mixing device 15 wherein it may be commingled with additional solvent supplied thereto 18 and discharges into a second settling chamber I8 provided like the first one with an insulating coating 88 and a heating coil 8|. After standing with the two layers separate, the bottom layer is withdrawn through line 82 and subjected again to another extraction. This time with a solvent of still lower temperature. Additional solvent is supplied through line 83 and the oil and solvent pass through mixing device 84, line 88, heating means 88 and line 81 into a third settling chamber 88, provided with insulating coating 88 and heating coil 88. A rd separation occurs and the bottom layer m y be withdrawn and sub- Jected to as many further extractions with solvent at progressively lower temperatures as desirable.

If settling chamber 88 is taken as the last chamber, the bottom layer will be withdrawn therefrom through line 8| and discharged into a still 82 wherein the solvent may be separated from the oil by distillation. Solvent vapors pass out of the still through line 83, flow through cooler 84, and the condensed solvent returns to solvent supply tank 68 through lines 95 and 88. The heavy oil remaining in the still is withdrawn therefrom through line 81.

The top layers are withdrawn from the several settling chambers through lines 88 and discharge into stills 88 wherein the solvent is separated from the oil by distillation. Solvent vapors pass out of stills 89 through lines I88, and flow through coolers IN. The condensed solvent then returns to solvent supply tank 85 through lines I82, I83, and 86. The light oil remaining in stills 89 is withdrawn therefrom through lines I84. The several fractions of light oil so obtained may be blended in any desired proportions, or may be maintained separate and worked up into several different light oil fractions. It will be understood that in place of using a separate still for the top layer from each settling chamber, a single still into which the top layers from all the settling chambers discharge may be used. Any other arrangement of stills may be made.

Referring to Figure 4 which illustrates a type of apparatus for carrying out a counter-current treatment of both the lighter and heavier fractions in a series of stages, the apparatus is in general similar to that shown in Figure 3 with these exceptions; the bottom layer formed in the first settler instead of being forwarded to the second mixer and-settler is removed through line II8; the top layer formed in the first settler is withdrawnthrough line III and passed to the second mixer and settler; the bottom layers from the second and third settlers are withdrawn through lines H2 and H3 respectively, and introduced into the mixers ahead of the first and second settlers respectively. In other words, the bottom layers are continuously withdrawn and returned to the next preceding stage instead of being forwarded to the next succeeding stage as in Figure 3, and the top layer in each settler is forwarded to the next succeeding stage instead of being removed as in Figure 3.

' The top layer from the final settler is removed through line I and passed into a still wherein the oil is separated from the solvent. In this method of operation the final top layer comprises an oil of greatly improved color over the original oil. It should be noted that in this method of operation the temperature is progressively increased from stage to stage instead of progressively decreased as is the case in treating the bottom layer in successive stages as in Figure 3. In other respects the apparatus in Figure 4 may be substantially similar to that in Figure 3, allowing for obvious modifications.

In the operation of our process the principal variable factors are the type of material select d as the feed oil, the kindoi light hydrocarbon solvent, the proportion of solvent to oil, the temperature at which the treatment is carried out and the pressure maintained.

In general, our process is applicable to any type of heavy hydrocarbon material, whether obtained from petroleum oil or its products of distillation or cracking, or from the products of the destructive distillation or hydrogenation of petroleum oils, coals, tars, pitches, shales, lignites, bitumens and the like. Our process is also applicable to synthetic hydrocarbon oils, waxes or resins, prepared for example by condensation or polymerization processes. It will be understood that at the temperatures at which the extraction is carried out, most of the normally solid hydrocarbons are above their melting points and therefore have substantially the ,same solubility characteristics as oils. Our process is particularly adapted, however, to the fractionation, purification and decolorization of petroleum oils, especially the lubricating fractions thereof.

The type of light hydrocarbons that may be used as the solvent in our process comprise generally hydrocarbons of 1 to carbon atoms ormixtures of any 2 or more of such hydrocarbons. Thus methane, ethane, propane, butane, pentane, ethylene, propylene, butylene, amylene, and isomers of these may be used. The presence of small quantities oi'higher molecular weight hydrocarbons is not especially harmful but in general it is desirable. to avoid the presence of these higher hydrocarbons. Ethane, propane and bu tane, or mixtures of ethane and propane or propane and butane arev particularly satisfactory solvents for our purposes. The gases obtained in the cracking of petroleum distillates and in the stabilization of gasolines are generally rich in the lighter hydrocarbons such as ethane, propane and butane and they furnish a convenient and readily available source of the solvent hydrocarbons.

The proportion of solvent to oil may be varied within wide limits, but between 3 and 15 volumes of solvent per volume of oil is satisfactory for most purposes. Between 8 and 12 volumes of solvent per volume of oil'is an especially suitable proportion.

The temperatures employed in the operation of the process in general range from the critical temperature to 10, 50, 100, 125 F. or more below the critical temperature of the particular light hydrocarbon selected as the solvent. Thus for propane which has a critical temperature of about 212 F., temperature may be decreased progressively from say 200 F. to 175 to 150 to 100 to 75 F., and so on, the density and consequently the selectivity thereof increasing and decreasing respectively with the decreasing temperature. For butane and pentane the temperatures of operation will be correspondingly higher and may be readily determined from the critical temperature of each.

when using solvents comprising mixtures of two or more light hydrocarbons, temperatures higher than those used with the lighter of the two or more hydrocarbons alone are generally required in order to obtainthe same selectivity. Thus when using a mixture of propane and hutane, the temperature necessary to obtain the same selectivity as exhibited by propane alone at a particular temperature must be near or above the critical temperature of propane but below the critical temperature of butane. For example, a heavy bottoms oil obtained from a Ranger crude is treated with 8 volumes of propane per volume of oil at a temperature of'about 158 F. and an 80% yield of an oil having a Saybolt viscosity at 210 F. of 114 secondsand a, color (Robinson) of 2% (dilute) is obtained. When a solvent comprising 8 parts of propane to 1 part of butane is used it is necessary to treat at a temperature of 180 F. in order to obtain the same yield of the same quality oil.

Similarly when using a solvent comprising ethane and propane, higher temperatures are necessary than if ethane alone is used in order to obtain the same selectivity in each case.

The pressure in our process should in general be maintained suflicientiy high to retain the light hydrocarbons in liquid phase at the temperature of working, but preferably not substantially greater than the equilibrium vapor pressure of the liquid at that temperature. This pressure will be between say slightly above atmospheric and 50 or more atmospheres depending upon the particular components of the solvent and the temperature at which the treatment is carried out. If the solvent comprises a mixture of light hydrocarbons, the pressure necessary will be close to the equilibrium vapor pressure of the lightest component of the solvent which is present in substantial amount.

The type of operation indicated in Figure 1, that is, a single extraction with solvent at a high temperature is especially adapted for obtaining from a heavy oil a fraction of better quality with respect to viscosity temperature characteristics and gravity. It is also adapted for separating a heavy lubricating fraction into a lighter fraction and a heavier fraction, both of which fractions differ in characteristics from the original oil.

The types of operation indicated by- Figures 2, 3, and 4, that is, counter-current or repeated intermittent extraction, are especially adapted for decolorizing and highly purifying heavy petroleum oil fractions and obtaining therefrom vainable lubricating 0115. By means of the successive treatment with solvent of progressively changing density it is possible to extract from the oil solid impurities which could not be removed in a single extraction. In the case of intermittent extraction it is possible to obtaina plurality of oil fractions of dissimilar characteristics, and these may be blended in any proportions to obtain blended oils of any desired characteristic. It is also possible by intermittent extraction to obtain in the last steps oils of extremely high viscosities, say from 1000 to 5000 seconds Saybolt viscosity at 210 F. Oils of these high viscosities cannot ordinarily be obtained by the usual fractionating means due to the fact that they decompose or break down at the temperatures necessary to vaporize them even when distilled under high vacuum. Moreover, all of the several fractions into which the heavy oil is separated by our process are characterized by much greater stability to heat and oxidation than fractions obtained by distillation.

Prior to treatment according .to this process, the oils may be subjected to preliminary purification treatments. Thus oils initially rich in asphaltic bodies may first be treated to remove a substantial portion of these materials. One

method of removing asphaltic bodies which is especially convenient in connection with the present process is to treat the oil with liquefied hydrocarbons such as propane or propane and ethane at normal temperatures, say around 50 to 100 F. In this way the asphaltic bodies are thrown out of the oil in a hard, granular substantially oil-free condition and the remaining oil is already in solution in the light hydrocarbon used in the high temperature treatment of the process herein described. Other methods of removing asphalt may of course be used.

The oils may also be subjected to hydrogenation, phenol extraction, aluminum chloride digestion, acid and clay treatment and so forth either preceding or following subjection to the light hydrocarbon solvent treatment. Dewaxing also may precede or follow the solvent treating.

and any suitable method of dewaxing may be used.

Following the purification of the material in accordance with the method outlined above, and before removing the solvent therefrom, a still further purification may be conveniently and advantageously effected by filtering the flux while still at the high treating-temperature through a bed of adsorptive material such as clay, charcoal and the like. Filtration of the oil or other hydrocarbon material while in hot light hydrocarbon solutionproceeds at an extremely rapid rate and substantially larger yields of oil per ton of clay are obtained than can be obtained by filtration in naphtha solution. The extent of the additional purification moreover is substantial, and the oils filtered in this manner are comparable in purity. Y and color to oils obtained only after repeated subjection to other methods of purification.

It will be understood of course that the hydrocarbon material may be filtered through the solid adsorptive media while in hot light hydrocarbon solution without a preliminary purification such as described above. This would be particularly advantageous if the initial material contains only a relatively small amount of colored or normally solid bodies.

As an illustration of the type of operation shown in Figure 1, a heavy dark-colored residuum obtained from a Ranger crude is first partial ly purified by treatment with propane at F. By this treatment a large proportion of the asphaltic material is precipitated from the residuum. The partially purified oil then has the following characteristics:

Gravity, A. P. I degrees 22.5 Saybolt viscosity 210 F seconds 133.4 Conradson carbon 2.48 Color, Robinson (dilute) 3/4 This oil is then diluted with 8 volumes of propane and the mixture heated to 183 F. whereupon two layers form. After allowing the mixture to stand at this same temperature the two layers are separated and the propane distilled oil from each. The two oil fractions so obtained have the following characteristics:

The following table illustrates the eflect of varying the temperature on the selectivity of the light hydrocarbon. The oil used is the same Ranger residuum as was used in the above example. The light hydrocarbon comprises propane and is used in the proportion of 8 volumes of propane to 1 volume of oil. The pressures maintained at each temperature are substantially the saturated vapor pressures of propane at those temperatures:

This invention is not limited by any theories of its mechanism nor by any details or data which have been given merely for purposes of illustration, but is limited only in and by the following claims in which we wish to claim all novelty inherent in the invention.

We claim:

1. The method of treating heavy hydrocarbon oils which comprises flowing a stream of such oil counter-current to and in intimate contact with a stream of a light hydrocarbon solvent the temperature of which is progressively increased in the direction of its flow from a temperature substantially above the wax separation temperature to a temperature near the critical temperature of the solvent, removing a stream of oil and solvent and recovering the oil therefrom.

2. Method according to claim 1 in which the initial temperature is from 75 to 125 F. below the critical temperature of the light hydrocarbon solvent and the final temperature is within 10 to 50 F. of the critical temperature of the solvent.

3.' Method according to claim 1 in which the light hydrocarbon solvent comprises a hydrocarbon of 3 carbon atoms.

4. Method according to claim 1 in which the light hydrocarbon solvent comprises hydrocarbons of 2 and 3 carbon atoms.

5. The method of purifying and decolorizing a lubricating oil fraction of petroleum which comprises causing a stream of the oil to flow in counter-current relation to and in intimate contact with a stream of alight hydrocarbon solvent comprising propane, progressively increasing the temperature of the solvent in the direction of its flow from a point about F. below to a point within a few degrees of the critical temperature of propane, removing a stream of oil and solvent, and recovering the oil therefrom.

6. In the process of fractionating heavy mineral oils by means of light hydrocarbons such as ethane, propane and butane at temperatures within about 50 F. of the critical temperature of the light hydrocarbon, the method which comprises eifecting separation at temperatures successively increasing from about 50 F. below the critical temperature of said light hydrocarbon to temperatures near said critical temperature.

7. The method of treating a heavy hydrocarbon oil which comprises diluting the oil with several volumes of a liquefied normally gaseous hydrocarbon, heating the mixture to a temperature about 50 F. below the critical temperature of the liquefied hydrocarbon at which the oil is caused to separate into two liquid fractions, separating,

the two fractions, subjecting the lighter of the two fractions to treatment with additional liquefied hydrocarbons in a series of stages at temperatures increasing to near the critical temperature of the liquefied hydrocarbon in the last stage, returning the heavier fraction from each stage to the next preceding stage, and removing the liquefied hydrocarbon from the lighter fraction obtained in the last stage.

. 8. The method of treating a heavy asphalt containing hydrocarbon oil which comprises diluting the oil with several volumes of a liquefied normally gaseous hydrocarbon, heating the mixture to a temperature about 50 F. below the critical temperature of the liquefied hydrocarbon, removing the heavy asphalt-containing layer thereby caused to precipitate, heating the remaining solution to a temperature about 10 F. higher than that at which the asphalt-containing layer was caused to separate whereby the oil is separated into a soluble liquid fraction and an insoluble liquid fraction, subjecting the soluble fraction to treatment with additional liquefied hydrocarbon in a series of successive stages at increasing temperature, the temperature in the-last stage being close to the critical temperature of the liquefied hydrocarbon, removing the insoluble fraction from each stage and returning it to the next preceding stage, and recovering oil from the soluble fraction obtained in the last stage.

9.' Process according to claim 8 in which pressure is maintained throughout the treatment sufficient to retain the liquefied hydrocarbon in liquid phase. I

JAMES M. WHI'I'ELEY. GUSTAV A. BEISWENGER.

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