US3153623A - Deashing of residua - Google Patents

Description

Oct. 20, 1964 1. A. ELDlB ETAL DEASHING OF RESIDUA 3 Sheets-Sheet 1 Filed April '7, 1961 GAS ETC.

A H T H P A N INTERMEDIATE CUT DEASHED OIL ASHER a SETTLER WASHED RESIDUE TO DRIER FIGURE l m m m m dmK N b A n .lr 0 w mm N R aw ABWHN mm P a mm m ehhh WHCGC Oct. 20, 1964 l. A. ELDlB ETAL DEASHING OF RESIDUA 3 Sheets-Sheet 2 Filed April 7, 1961 9 x 3 muzfio zoo QEGMEm FIGURE 2 HlGH VOLTAGE POWER SUPPLY H-SHAPE ELECTROPHORESIS APPARATUS PLATINUM ELECTRODE FIGURE 3 INVENTORS Ibrahim A. Eldib Hermon Bieber Clark Edward Adams Glen Porter Homner Charles Newton Kimberlin, Jr. 50' W 27-74 ATTORNEY Oct. 20, 1964 l. A. ELDlB ETAL 3,153,623

DEASHING 0F RESIDUA Filed April 7. 1961 s Sheets-Sheet s STREAM g LLI E $3 I 0. 5:: g0) 05 g 2 g m :2 an

m r 9 u.| O O: :3 o E 5 E O (I) I LIJ o (9 E5 E m (0 E fim l-l-l 2 INVENTORS Q Ibrahim A. Eldib Hermon Bieber Clark Edwards Adams Glen Porter Homner Charles Newton Kimberlin, Jr.

ATTORNEY United States Patent ()fiice 3,153,623 Patented Get. 20, 1964 3,153,623 DEASHING F RESZDUA Ibrahim A. Eldih, Union, and Herman Biehcr, Kenilworth, NJ and (Jlark Edward Adams, Glen Porter Hamner, and Charles Newton Kimberlin, Jru, Baton Rouge, La, assignors to Esso Research and Engineering Company, a corporation of Delaware Filed Apr.,7, 1%1, Ser. No. 101,387

4 Claims. (Cl. 204-184) The present invention relates to the removal of metallic contaminants from petroleum oils and more particularly relates to an improved process for the removal of complex organo-metallic compounds of the porphyrin type from high boiling petroleum gas oils and in particular from residual oils.

The use of residual hydrocarbon oils, either alone or mixed with, for example, oil distillates as fuel for gas turbines is highly economically attractive. However, the ash forming constituents generally occurring in residual hydrocarbon oils constitute a severe drawback to the use of the latter as fuel oil for this purpose. The ash forming constituents, which in all probability are nonvolatile porphyrins associated in particular with vanadium, nickel and iron, have a severe fouling and corrosive effect upon installations in which the oils are used. They attack the refractories used to line boilers and combustion chambers, and corrode turbine blades.

Though numerous methods have been proposed for removing these contaminants from high boiling hydrocarbon oils, they have been largely ineifective, generally resulting in loss of substantial quantities of oil, and in most cases are prohibitively expensive. It has hitherto been suggested to coagulate the metal with a coagulant or a solvent, but separation and filtration are difficult, expensive, time consuming and inefilcient.

It is a principal object of the present invention to provide an improved process for treating metal-contaminated heavy hydrocarbon oils, and in particular residual oils. A further object of the present invention is to provide a process wherein asphaltenes and porphyrins are more economically removed from hydrocarbon oils.

These objects will be more clearly understood and other objects will be evident from the detailed descrip tion hereinafter.

It has previously been found that metals may be removed from heavy oils and residua, in association with asphaltene fractions, by subjecting the oils to an electrophoretic action by means of an applied electrical field. The metal is probably present as a colloidal porphyrinic compound, and it was hoped that these porphyrins could be coagulated by a high voltage electric field. However, it has not been possible to clfect separations of this kind without the initial application of an extended heat soaking treatment at temperatures of 650 to 850 F. for periods up to hours. This treatment served to change the nature of the colloid porphyrin and was accompanied, unavoidably, by some cracking, forming undesirable naphtha and light gases.

The concentration of metallic constituents in crude oil varies from 1 to 500 parts per million, and most of this is concentrated in the residual fraction. Heavy gas oils distilled from typical crudes may contain from 1 to 20 pounds of metallic contaminants per 1000 barrels, while residual fractions may contain as much as 200 pounds per 1000 barrels.

In accordance with one embodiment of the present invention there is incorporated in the oil to be treated electrophoretically certain ionizable, oil-soluble additives which are preferentially adsorbed by the metal-containing compound. The complex thus formed between the ionizable additive and the metal-containing compound may then be far more readily removed from the bulk of the oil by migration to one of the electrodes in an electric field or current. Furthermore, it has been found that this migration and separation occurs without the need for a heat soaking step or other thermal treatment.

Additives applicable to this embodiment are very spe cific as they must be (1) ionizable to impart an electric charge to the metal-containing molecules or particles, (2) partially oil-soluble to be able to react with the metalcontaining molecules or particles, and (3) selectively adsorbed by the metal-containing molecules or particles. These additives are preferably of the surface active type of strongly ionic molecules containing sufiicient organic ty-pe substituents to make them oil-soluble. As noted in the examples, it has been found that the additive may be either of the cationic or anionic type. Other materials than those in the examples will be applicable but it is obvious they must have the desired properties noted above. It may be desirable to add the ionic material in a hydrated form or in a solvated form in order to facilitate the introduction of the additive and to enhance its activity.

Turning now to FIGURE 1, which shows a preferred embodiment of the present invention, a crude oil is passed via line 6 to mixing zone 7 Where it is preferably diluted with 0.1 to 10 volumes, preferably 0.5 to 5 volumes of a light hydrocarbon, such as propane, butane or a naphtha fraction boiling in the range of 55 to 300 F. Precipitation of a light, fiocculent precipitate of asphaltenes may occur at this point but this precipitate cannot be migrated in an electric field or current unless the feed has been heat soaked.

To this mixture there is now added, preferably with the solvent, about 0.05 to 5%, preferably 0.2 to 2% (based on oil feed), of the ionizable additive and mixing is continued to cause uniform distribution throughout the mixture.

The mixture of oil, solvent, and precipitate is passed through line 8 to electrical precipitation zone 10, which, though it may be of conventional design, is preferably a direct current precipitator and the mixture subjected to the effects of an electrical field. One or more receiving electrodes are employed, preferably equipped with vibrating means to remove deposited material. The voltage between the electrodes may be varied appreciably and may be in the range of from 1,000 to 50,000 volts. The temperature within the electrical precipitator 10 is in the range of about to 400 F.

The coagulated residue is withdrawn as a semi-fluid or slurry and passed via line 12 to wash-settling vessel 14. Here the residue may be washed with fresh naphtha admitted through line 20 to remove occluded oil. The washed residue may be separated from the wash liquid by settling and the wash liquid recycled via line 18 to dilute the incoming feed. It is understood that other means of separating occluded oil from the precipitated metal residue may be employed. Thus a second electrical precipitation step may be used, or the washing step may be carried out in a filter or other conventional means. The washed residue may be dried, as by spray drying, and employed as fuel or as desired. By operating in the manner described, the oil removed from the precipitate is returned to the process for ultimate recovery.

Returning now to precipitator 10, the oil layer is passed to distillation tower 24 via line 22 where the desired naphtha cut employed as solvent is taken overhead through line 30; light gases are Withdrawn through line 26. Demetallized oil is taken as a bottoms cut, and is found to be substantially improved not only in metals content but also in such important respects as carbonforming constituents, nitrogen compounds, gravity, and

viscosity. Thus the gas oil fraction may be fed directly to the catalytic cracking process without danger of catalyst fouling. The fuel oil fraction is also now a premium fuel.

The process of the present invention may be further illustrated by the following specific examples.

EXAMPLE 1 A Bachaquero crude topped at 400 F. and containing 400 ppm. of vanadium and 50 ppm. of nickel was mixed with five volumes of n-pentane and one ml. of Cyquest 40 (40% aqueous solution of sodium salt of ethylene diarnine tetraacetic acid) was added with stirring. Approximately 200 cc. of this solution were placed in an electrical precipitator consisting of a metal cylinder of 52 mm. LI). and a concentric metal insert finger of 33 mm. 0.1). A DC. potential of 2,000 volts was applied across the electrodes for about five minutes and resulted in the deposit of dense black material on the cathode (finger). Analysis of the resulting oil after removal of pentane diluent showed 105 ppm. V and 20 ppm. Ni. The feed treated in the same way with n-pentane but in the absence of the Cyquest 40 did not give a deposit in the electric field. Filtration of the precipitate from the feed mixture and removal of diluent gave an oil product containing 128 ppm. V and 21 ppm. Ni.

EXAMPLE 2 The Bachaquero topped crude noted in the example above was treated in the same way with n-pentane, etc., except that the additive added consisted of 0.5 g. of 'I-lymine X (99% paradiisobutyl cresoxy ethoxy ethyl dimethyl benzyl ammonium chloride) and 1 cc. of Arquad 18 (50% isopropanol solution of octadecyl trimethyl ammonium chloride). A similar deposit of dense black material was obtained on the cathode. Analyses of the resulting oil obtained after removal of the pentane diluent showed 98 ppm. V and 21 ppm. Ni.

The process of this embodiment of the present invention may be modified in many respects. Thus, it may be desirable in some cases to carry out the electrical precipitation step without the presence of a solvent; this may be effected at somewhat elevated temperatures in the range of 200 to 500 F. in order to reduce the viscosity of the feed.

In another embodiment of the present invention the solvent added to reduce the viscosity of the oil acts both as a diluent and as an additive. It was found that nitrobenzene has very special properties. When petroleum fractions, asphaltic or non-asphaltic, inclusive, are diluted with nitrobenzene, the solution exhibited a significant electrical conductance (conductance-:reciprocal resistance=l/R), while in benzene or naphtha no or very little conductance could be observed. FIGURE 2 illustrates this point.

Apparently in a medium of low dielectric constant such as benzene (2.28 e. units), the electrostatic attractive forces between positive and negative ions are large. Such solvents would, therefore, be expected to have a small dissociating influence on an electrolyte; a medium of high dielectric constant such as nitrobenzene (34.8 e. units), however, should favor dissociation. With high dissociation, the conductance of the solution is high and migration of charged particles is favored. The nitrobenzene accomplishes this.

It is very important in any type of electrical separation process that the dielectric constants of the medium be as high as possible, i.e., the resistance (R) be as low as possible. This is because the quantities of substance set free at the electrodes are directly proportional to the quantity of electricity which passes through the solution. The quantity of electricity is generally measured in terms of amperes (I). For a given amount of electrical power purchased, watts=l R the smaller the resistance (R), the larger is the amount of current available (I) for electrical deposition or migration.

4: This embodiment of the present invention is shown in the following examples.

EXAMPLE 3 Solutions of 12.5 asphaltenes in nitro benzene were electrophoresed for several hours at 500 volts. The electrophoresis was carried out in an H-shaped electrophoresis apparatus equipped with platinum electrodes. A description of this apparatus and a wiring diagram are shown in FIGURE 3. The asphaltenes were deposited on the cathode and must therefore have been positively charged. Analysis of the asphaltenes solution in the cathode compartment showed that it was richer in vanadium and nickel than the asphaltenes solution remaining in the anode compartment. Analysis of the asphaltenes on the cathode showed that they were richer Solutions of 12.5% asphaltenes in nitro benzene were electrophoresed for several hours at 3000 volts. The electrophoresis was carried out in an apparatus similar to that described in Example 3. In this case, the asphaltenes were deposited on the anode and must therefore have been negatively charged. The asphaltenes in the anode compartment showed that they were richer in vanadium and nickel than the asphaltenes remaining in the cathode cornpartment or the feed asphaltenes. The results of this experiment are shown in Table II.

Table II P.p.m. of Metals- Feed Asphaltenes Asphal- Voltage and Temp. tenes,

ppm. Anode Cathode Compart- Compartment ment v 2,130 a, 030 1, 869 Ni 258 402 21 It must be noted here that the metals were concentrated in the anode rather than the cathode compartment. It is conceivable that at high voltages the electrical charges on the asphaltenes are reversed so that they becom positively rather than negatively charged. The important thing that the experiment points out is that the asphaltenes migrate under the influence of an applied potential.

EMMPLE 5 In this case, nit-r0 benzene was added to a petroleum oil residuum and the mixturewas electrophoresed at 500 volts in the same apparatus as that described in Example 3. Here again, at the low voltage range, the vanadium and nickel were richer in the cathode than the anode compartment, because the asphaltenes with which these metals are associated migrated under the influence of the applied potential. Since an oil rather than asphaltenes were electrophoresed, no deposition of asphaltenes on the cathode was noted. The results of this electrophoresis experiment are shown in Table III.

In this case, nitro benzene was added to a petroleum residuum and the mixture was electrophoresed at 3000 volts in the same apparatus as that described in Example 3. Again, at this high voltage vanadium and nickel, like in Example 4, were richer in the anode than the cathode because the asphaltenes with which these metals are associated migrated under the influence of the applied potential. Since an oil rather than asphaltenes was electrphoresed, no deposition of asphaltenes on the anode was noted. The results of this electrophoresis experiment are shown in Table IV.

Table IV P.p.m. oi Vanadium (V) Separation Factor, System in Voltage V in Nitrobenzene and Temp. Anode Cath- Anode/ Feed Soluode in tion Solu- Cathode tion 25% Residuum. 1,500, 80 F 100 105. 91.3 1.16 50% Residuum- 6,000, 200 F... 200 218 191 1. 14

It was observed again in the case of the electrophoresis of the residuum that at high voltages the asphal-tcnes rich in vanadium and nickel must become negatively charged and therefore migrate to the anode.

These results show that it is possible to separate the asphaltenes which are rich in vanadium (and nickel) from petroleum. With the use of nitrobenzene it is not necessary to heat soak the oil for extended periods of time. Heat soaking is undesirable because it creates a large amount of asphaltenes which have no use. Also, due to the thermal effects the oil is cracked, and low boiling distillates are obtained.

The separation factor (concentration of vanadium at one electrode/vanadium at opposite electrode) can be multiplied severalfold by making a countercurrent system consisting of a number of stages, a few of which are indicated in the attached FIGURE 4. The feed (oil plus nitrobenzene) enters at about the middle of the cascade. The electrophoresis cells (referred to here as stages) to the right of the feed stage are referred to as the stripping section and those to the left of the feed stage, as the enriching section. These terms imply that the oil moving into the stages to the right of the deed stage is stripped of metals, while that moving to the left of the feed stage is enriched in metals.

Considering the stage marked B, the feed enters at the middle of the stage, shown dripping to assure that stages are electrically insulated from each other. Assuming that a high voltage operation will be undertaken, as in Examples 4 and 6, and that the metal-rich asphaltenes will migrate to the anode, the following operation can be visualized. A metals and asphaltenes-rich oil migrates to the anode through a porous partition. The oil poor in metals migrates also through the partition, to the cathode. The oil poor in metals then flows to stage A. Here, it undergoes further electrophoresis, so that the metal-poor oil becomes poorer in metals content. Turning once again to stage B, it is seen that the oil rich in metals, which has migrated to the anode, is pumped to stage C where it joins the metalspoor oil from stage D. This mixture'plus the feed then undergo electrophoresis in stage C. The metals-poor oil goes to stage B, while the metals-rich oil returns to stage D to be recycled. In this way the oil moving right toward stage A becomes increasingly poor in metals, while the oil moving toward stage E becomes increasingly rich in metals.

The cells, each representing a stage, can be connected in series to a high voltage power supply. The electrical Wiring is shown in FIGURE 4.

If the voltage used is low (500 volts) then the asphaltene-rioh metals will migrate to the cathode in the presence of nitrobenzene as a solvent. The concept described in FIGURE 4 not be changed except that the metalsrich asphaltenes will come out from stage A at the cathode compartment, while the metals-poor asphaltenes will come out from stage E at the anode compartment.

What is claimed is:

1. An improved process for upgrading a metal contaminated petroleum residual oil fraction which comprises adding a sodium salt of ethylene diamine tetraacetic acid to said fraction, passing said mixture to an electrical precipitation zone, applying a DC. voltage to said mixture and separating as a sludge metallic contaminants from said oil.

2. An improved process for upgrading a metal contaminated petroleum residual oil fraction which comprises adding to said fraction a mixture of paradiisobutyl cresoxy ethoxy ethyldimethyl benzyl ammonium chloride and an isopropanol solution of octadecyl trimethyl ammonium chloride, passing said mixture to an electrical precipitation zone, applying a DC. voltage to said mixture and separating as a sludge metallic contaminants from said oil.

3. An improved process for upgrading a metallic contaminated petroleum fraction including constituents boiling above about 950 P. which comprises adding to said fraction an oil-soluble additive, selected from the group consisting of paradiisobutyl cresoxy ethoxy ethyl dimethyl benzyl ammonium chloride, octadecyl dimethyl ammonium chloride and the sodium salt of ethylene diamine tetraacetic acid and mixtures thereof, subjecting said fraction at elevated temperature to a direct current electrical field, and recovering an oil product depleted in metallic constituents.

4. An improved process for upgrading a metal contaminated petroleum residual oil fraction which comprises diluting said fraction with 0.3 to 3 volumes of a low dielectric constant solvent, adding 0.05 to 5% based on oil, an oil-soluble additive, selected from a group consisting of paradiisobutyl cresoxy ethoxy ethyl dimethyl benzyl ammonium chloride, octadecyl dirnethyl ammonium chloride and the sodium salt of ethylene diamine tetraacetic acid and mixtures thereof, passing said mixture to an electrical precipitation zone, applying a DC. voltage of about 1,000 to 50,000 volts to said mixture, maintaining a temperature of about 200 to 400 F. Within said zone, ant:1 selparating as a sludge metallic contaminants from sa1 o1 References Cited in the file of this patent UNITED STATES PATENTS 2,395,011 Perkins Feb. 19, 1946 2,474,411 Bersworth June 28, 1949 2,530,366 Gray Nov. 21, 1950 2,778,777 Powell Jan. 22, 1957 2,818,374 Certa Dec. 31, 1957 2,870,081 Frey Jan. 20, 1959 2,884,375 Seelig et a1 Apr. 28, 1959 2,996,442 Eberly et a1 Aug. 15, 1961 OTHER REFERENCES Versenes, Bersworth Chemical Co., Framingham, Mass, February 1952, pp. 53, 54 (Sec. 2).

Pink: The Electrochemical Society, Deposition of Synthetic Resins, pages 325-326, volume 94, December 1948.

Claims (1)

1. AN IMPROVED PROCESS FOR UPGRADING A METAL CONTAMINATED PETROLEUM RESIDUAL OIL FRACTION WHICH COMPRISES ADDING A SODIUM SALT OF ETHYLENE DIAMINE TETRAACETIC ACID TO SAID FRACTION, PASSING SAID MIXTURE TO AN ELECTRICAL PRECIPITATION ZONE, APPLYING A D.C. VOLTAGE TO SAID MIXTURE AND SEPARATING AS A SLUDGE METALLIC CONTAMINANTS FROM SAID OIL.

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