INTEGRATED PROCESS FOR PRODUCING ANODE GRADE COKE

Abstract

The invention relates to processes for producing anode grade coke from whole crude oil. The invention is accomplished by first deasphalting a feedstock, followed by processing resulting DAO and asphalt fractions. The DAO fraction is hydrotreated or hydrocracked, resulting in removal of sulfur and hydrocarbons, which boil at temperatures over 370 C., and gasifying the asphalt portion in one embodiment. This embodiment includes subjecting hydrotreated and/or unconverted DAO fractions to delayed coking. In an alternate embodiment, rather than gasifying the asphalt portion, it is subjected to delayed coking in a separate reaction chamber. Any coke produced via delayed coking can be gasified.

Claims

1. A method for producing anode grade coke, comprising: (i) solvent deasphalting a hydrocarbon feedstock to produce an asphalt fraction and a deasphalted oil (DAO) fraction, in a first reaction chamber; (ii) processing said DAO fraction and asphalt fraction in separate, second, third, and fourth reaction chambers; (iii) hydrocracking said DAO fraction in said second reaction chamber to remove sulfur and nitrogen therefrom and to distill any hydrocarbons contained in said DAO which have a boiling point over 370 C. wherein said second reaction chamber is a fixed bed, ebullated bed, or slurry bed chamber; (iv) subjecting any hydrotreated or unconverted DAO fraction to delayed coking in a third chamber, and (v) gasifying said asphalt fraction via combining it with oxygen and steam, in said fourth reaction chamber, to produce hydrogen therefrom.

2. The method of claim 1, further comprising gasifying any coke produced in step (iv).

3. The method of claim 1, comprising introducing any hydrogen produced in said third reaction chamber into said second reaction chamber.

4. The method of claim 1, wherein said hydrocarbon feedstock is crude oil and said solvent deasphalting comprises mixing said crude oil with a paraffinic solvent containing C.sub.3-C.sub.7 carbon atoms, at a temperature and a pressure below critical temperature and critical pressure of said solvent.

5. The method of claim 4, wherein said solvent comprises n-butane and isobutane.

6. The method of claim 1, further comprising contacting said crude oil with a solid adsorbent.

7. The method of claim 4, comprising mixing said crude oil and solvent at a temperature and pressure below the critical temperature and critical pressure of said solvent.

8. The method of claim 4, wherein said crude oil and solvent are combined at a weight ratio of from 10:1 to 200:1 w/w.

9. The method of claim 1, comprising hydrocracking said DAO at a pressure of from 100-200 bars, a temperature of from 350 C. to 450 C., an LHSV of from 0.1 to 4.0 h.sup.1, and a hydrogen:DAO ratio of from 500 to 2,500 SLt/Lt.

10. The method of claim 1, comprising hydrocracking said DAO in a series of multiple chambers.

11. (canceled)

12. The method of claim 1, comprising hydrocracking said DAO in the presence of a catalyst, which contains from 2-40 wt % active metal, a pore volume of from 0.33-1.50 cc/gm, a surface area of 250-450 m.sup.2/g, and an average pore diameter of at least 50 Angstroms.

13. The method of claim 12, wherein said active metal is a Group VI, VII, or VIIIB metal.

14. The method of claim 12, wherein said active metal comprises Co, Ni, W, or Mo.

15. The method of claim 12, wherein said catalyst is presented on a support.

16. The method of claim 15, wherein said support comprises alumina, silica, or a zeolite.

17. The method of claim 16, wherein said support is a zeolite with FAU, MOR, BEA or MFI topology.

18. The method of claim 17, wherein said zeolite has been modified by treatment with at least one of steam, ammonia, or acid, and contains at least one transition metal.

19. The method of claim 18, wherein said at least one transition metal is Zn or Ti.

20. The method of claim 1, comprising gasifying said asphalt fraction at a temperature of from 900 C. to 1700 C., and a pressure of from 20 bars to 100 bars.

21. The method of claim 1, further comprising adjusting the amount of asphalt and at least one of oxygen and steam in said third reaction chamber to provide a stoichiometric balance therebetween which results in partial combustion of said asphalt.

22. The method of claim 20, wherein said stoichiometric ratio based on the oxygen:carbon ratio is from 0.2:1:0 to 10:0.2 by weight.

23. The method of claim 20, comprising introducing asphalt and steam to said fourth reaction chamber in a ratio of from 0.1 to 1.0 to 10:0.1 based upon weight of carbon in said crude oil.

24. (canceled)

Description

BRIEF DESCRIPTION OF THE DRAWING

[0019] FIG. 1 shows a schematic depiction of the process of the invention, using a single reactor embodiment to reduce hydrocarbon containing feedstock.

[0020] FIG. 2 shows an embodiment of the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0021] The invention may be best understood by referring to FIGS. 1 and 2, which illustrates the general method of the invention as well as a system used in its practice.

[0022] Referring to FIG. 1, a feedstream of crude oil 10 is added to a reaction chamber 11, so as to solvent deasphaltize (SDA) it, thereby producing an asphalt fraction 12, and a fraction of deasphalted oil, or DAO 13 as referred to supra. The manner in which this fractionation can be accomplished is described, supra i.e., a paraffinic solvent containing one or more carbon atoms containing from 3-8, more preferably 3-7 carbons, is used. No catalyst or adsorbent is necessary; however, see U.S. Pat. No. 7,566,394, incorporated by reference, supra, teaching an improved deasphalting process using a sorbent. No distillation is used, nor are the light components separated.

[0023] The DAO 13 is transferred to a hydrocracking/hydrotreating zone 14. It is to be understood that, while FIG. 1 describes a single reactor, the various methods for hydrocracking, including once through, series flow, and two-stage reactions, may all be used. The reactor contains one or more catalysts which remove heteroatoms, such as sulfur and nitrogen from the DAO. Such catalysts are well known to the art, and are not repeated herein. Exemplary of such are catalysts described in, e.g., PCT/US11/46272 filed Aug. 2, 2011 and incorporated by reference herein. The cracking reaction takes place in the presence of hydrogen, which is supplied as explained infra.

[0024] It will be recalled that in addition to the DAO, solvent deasphalting of the crude oil produces an asphalt fraction 12. This asphalt fraction is transferred to a gasification chamber 15, together with oxygen and steam, which are not shown. These components, i.e., the oxygen and steam, may be supplied in pure form, or via, e.g., atmospheric air. The asphalt, oxygen and steam are combined, at temperatures and pressures which result in production of hydrogen. In the depicted embodiment, this hydrogen 18, is channeled to the DAO hydrocracking unit 14, to supply the hydrogen necessary for the hydrocracking process to take place. (It should be noted that the gasification of asphalt is an optional step, and may be replaced via, e.g., supplying an independent source of hydrogen). Various products, e.g., gases 19, and upgraded crude oil (distillates) 20, result, as well as unconverted DAO 21. This unconverted DAO is transmitted to a delayed coking chamber 22, and converted to anode grade coke 23, gases 24, and further distillates 25.

[0025] Turning to FIG. 2, as with FIG. 1, a source of crude oil 31 is provided to a solvent deasphalting unit 32. Following standard methods, deasphalted oil (DAO) 33, and asphalt 34 are produced. The DAO is transmitted to a hydrocracking or hydrotreating chamber 35, supplied with hydrogen 36, which can be provided as per the description supra. The products of standard hydrocracking are gases 37, distillates 38, and unconverted DAO 39, which moves to a delayed coking unit 40, where it is processed to gases 41, distillates 42, and anode grade coke 43.

[0026] Further processing of asphalt 34 takes place in a further chamber an asphalt oxidation chamber 44, where the asphalt can be oxidized with, e.g., air to produce higher grade asphalt, or it too may be subjected to delayed coking to produce fuel grade coke. The asphalt 45 can be sent to an asphalt pool.

[0027] By separating the asphalt component of the crude oil from the DAO, one eliminates problems such as the failing of catalysts by metals that are present in the asphalt fraction. Catalyst life cycles are increased, and the need for shut downs of reactors, and replacement of materials, are decreased.

[0028] In the process as described herein, the hydrocracking process takes place at standard hydrocracking conditions, i.e., pressures ranging from about 100 to about 200 bars, temperatures ranging from about 350 C. to about 450 C., LHSVs of between 0.1 and 4.0 h.sup.1, and hydrogen oil ratios of from about 500 to about 2,500 SLt/Lt.

[0029] Following this step, any hydrotreated, or unconverted DAO fraction moves to a third reaction chamber where it is subjected to delayed coking.

Example 1

[0030] This example describes an embodiment of the invention in which gasification of the SDA fraction was used to produce hydrogen, which was then used in the hydrocracking of the DAO fraction. It will be understood that the H.sub.2 may be supplied via other means.

[0031] A 1000 kg sample of crude oil was solvent deasphalted, using art known techniques, with butane solvents and adsorbents, in a reaction chamber, such as is depicted by 11 in FIG. 1. Prior to deasphalting, the crude oil was analyzed, and the results of this analysis are presented in the Table, column 1, which follows.

[0032] Following deasphalting, the asphalt fraction and deasphalted oil, or DAO, were also analyzed, and these results are presented in columns 2 and 3 of the Table.

[0033] The asphalt fraction was gasified by oxygen and steam combining it into membrane wall reactor or gasification chamber, depicted at 15 in FIG. 1. The mixture was heated to 1045 C., with a water to carbon ratio of 0.6 (in terms of weight), and an oxygen:pitch ratio of 1.0.

[0034] After gasification was completed, the raw syngas product was combined with steam that was produced by either a boiler or process heat exchanger to a water gas shift (WGS) reactor, which was operated at 318 C., one bar of pressure, and a water to hydrogen ratio of 3. This increased hydrogen yield.

[0035] All analyses and results are presented in the table which follows and which is elaborated upon infra:

TABLE-US-00001 TABLE 1 Summary of Components Column # 1 2 3 4 5 6 7 8 Stream Name Arab Deasphalted Upgraded Heavy CO Crude Oil Asphalt C1-C4 Crude Oil Oxygen Steam Hydrogen Feedrate kg 1000 922 78 4.8 930 78 46.8 13 Density Kg/Lt 0.8904 0.876 1.210 0.825 API Gravity * 27.4 30.0 14.6 40.1 Carbon W % 84.8233 85.04 78.36 Hydrogen W % 12.18 12.83 6.43 Sulfur W % 2.837 1.99 10.79 <20 Nitrogen ppmw 1670 535 9575 <20 MCR W % 8.2 2.55 61.3 Nickel ppmw 16.4 1 582 <1 Vanadium ppmw 56.4 1 172 <1 C5-Asphaltenes W % 7.8 C7-Asphaltenes W % 4.2 Toulene W % 0.0008 insolubles Ashes W % 0.014 H2 W % 99.5 H2S W % 2.47 NH3 W % 0.11 C1-C4 W % 100 36-190 W % 17.4 20.6 21.5 190-370 W % 25.8 29.0 36.0 370-490 W % 17.9 19.1 21.2 490+- W % 39.0 31.3 21.2

[0036] While gasification was taking place, the DAO portion was introduced to a standard, hydrocracking unit, shown in 14, and hydrocracked at 360 C., 115 bars of hydrogen partial pressure, with an overall liquid hourly space velocity of 0.3 h.sup.1, with a NiMo promoted, amorphous VGO hydrocracking catalyst and a zeolite catalyst designed for heavy oils, at a loading ratio of 3:1. See PCT/US 11/46272, incorporated supra, for the catalyst used herein.

[0037] Also encompassed are compositions where catalysts are presented on a supper, such as an alumina, silica, or zeolite support. Exemplary zeolite supports have FAU, MOR, BEA, OR MFI topology. See, e.g., U.S. Pat. Nos. 3,875,290; 3,948,760; and 4,346,067, all of which are incorporated by reference.

[0038] The products which left the hydrocracking chamber were analyzed for content of low molecular weight hydrocarbons (C.sub.1-C.sub.4), upgraded crude oil, oxygen, steam, and hydrogen. These values are presented in columns 4-5 in Table 1. The upgraded crude oil was also analyzed for various minor components, as well as boiling fractions, in the same way the crude oil, and DAO were analyzed. To elaborate upon Table 1, Column 1 presents the analysis of the crude oil (CO) used in the reaction. Column 2 is the analysis of the resulting DAO and Column 3, the asphalt fraction. Column 4 presents the information on the gas produced in the hydrocracking step, with Column 5, the upgraded crude oil. Finally, Columns 6, 7, and 8 refer to the reactants added to the reactors, as discussed supra.

Example 2

[0039] A 1000 kg sample of crude oil was solvent deasphalted using butane solvents and adsorbents, and techniques known to the art. Prior to this, the crude oil was analyzed, and the results are shown in column 1 of Table 2, which follows.

[0040] Following the deasphalting, both the asphalt fraction and the DAO were analyzed, and these results are also set forth in Table 2 as columns 2 and 3.

[0041] The DAO portion was introduced to a standard hydrocracking unit, and hydrocracked at 360 C., 115 bars hydrogen partial pressure, and an overall liquid hourly space velocity of 0.3 h.sup.1. As catalysts, a NiMo promoted, amorphous VGO hydrocracking catalyst, and a zeolite catalyst designed for heavy oils were used, at a loading ratio of 3:1.

[0042] Products leaving the hydrocracking chamber were analyzed for each of: (i) low molecular weight hydrocarbons (C.sub.1-C.sub.4), upgraded crude oil, oxygen, steam and hydrogen. All values are presented in Table 2.

[0043] The resulting upgraded fuel oil was then fractionated, using standard techniques, to secure gas distillates, and unconverted DAO. The unconverted DAO was then transmitted to a delayed coking unit, and subjected to standard processes to secure anode grade coke, distillates, and gases. Again, values are given in Table 2.

TABLE-US-00002 Stream# 1 2 3 4 5 6 7 8 9 10 Stream Name Arab Deasphalted Upgraded Unconverted Anode Heavy CO Crude Oil Asphalt C1-C4 Crude Oil Hydrogen DAO Grade Coke Gases Distillates Feedrate kg 1000 922 78 9.5 934 21 148 13 12 126 Density Kg/Lt 0.8904 0.876 1.210 0.811 API Gravity * 27.4 30.0 14.6 43.0 Carbon W % 84.8233 85.04 78.36 Hydrogen W % 12.18 12.83 6.43 Sulfur W % 2.8297 1.99 10.79 <20 <1 Nitrogen ppmw 1670 535 9575 <20 MCR W % 8.2 2.55 61.3 Nickel ppmw 16.4 1 582 <1 <1 Vanadium ppmw 56.4 1 172 <1 <1 C5-Asphaltenes W % 7.8 C7-Asphaltenes W % 4.2 Toluene W % 0.0008 insolubles Ashes W % 0.014 Composition W % H2 Kg/h 0.00 0.00 0.00 0.00 0.00 21.03 0.00 0.00 0.00 H2S Kg/h 0.00 0.00 0.00 0.00 23.01 0.00 0.00 0.00 0.00 NH3 Kg/h 0.00 0.00 0.00 0.00 1.01 0.00 0.00 0.00 0.00 C1-C4 Kg/h 0.00 0.00 0.00 9.47 0.00 0.00 0.00 9.18 0.00 36-190 Kg/h 17.4 20.6 0.00 0.00 224.59 0.00 0.00 0.00 18.72 190-370 Kg/h 25.8 29.0 0.00 0.00 371.80 0.00 0.00 0.00 55.86 370-490 Kg/h 17.9 19.1 0.00 0.00 189.46 0.00 0.00 0.00 51.40 490+- Kg/h 39.0 31.3 0.00 0.00 147.82 0.00 147.82 0.00 125.98

[0044] The foregoing disclosure sets forth the features of the invention, which is a simplified methodology for delayed coking of hydrotreated and/or unconverted DAO fractions produced when eliminating impurities in hydrocarbon containing feedstocks, such as crude oil, which does not involve distillation. To summarize, the crude oil is solvent deasphalted, resulting in DAO and asphalt. The DAO is then hydrocracked in the presence of a catalyst so as to desulfurize and denitrogenize it, and to convert any hydrocarbons, which have a boiling point over 370 C. into distillates. Any hydrotreated or unconverted DAO fractions are then subjected to delayed coking. Concurrently, the asphalt fraction is gasified so as to produce hydrogen. In one embodiment, the hydrogen is channeled back into the hydrocracking reactor and used in that process. The nature of the gasification feedstock will, of course vary and may include ash in an amount ranging from about 2% to about 10% of the total feedstock. The feedstock may be liquid or solid. Liquid feedstocks having components with boiling points of from about 36 C. to about 2000 C. are preferred. The feedstock may be, e.g., crude oil bituminous, oil, sand, shale oil, coal, or a bio liquid.

[0045] In practice, it is desirable to subject the crude oil to a paraffinic solvent to separate DAO and asphalt. The solvent comprises one or more C.sub.3-C.sub.7 alkanes, which may be straight chained or branched. Preferably, the solvent comprises one or, most preferably, a mixture of butanes. Solvation takes place at temperatures and pressures, which are below the critical values for both of these.

[0046] It is especially preferred to carry out the deasphalting step, discussed, in the presence of a solid adsorbent, preferably added in an amount sufficient to provide a hydrocarbon:adsorbent ratio of from 20:0.1 to 10:1, expressed in terms of W/W.

[0047] After separation, the DAO is transmitted to a hydrocracking unit, where hydrocracking is carried out at conditions which may vary, but are preferably a pressure of from about 100 to about 200 bars, a temperature of from about 350 C. to about 450 C., an LHSV of from about 0.1 to about 4.0 h.sup.1, and a hydrogen:oil ratio of from about 500 to about 2500 SLt/Lt. Any standard hydrocracking system may be used including single reactors, multiple reactors operated in series, fixed bed reactors, ebullated bed reactors, and so forth.

[0048] A catalyst is used in the hydrocracking process, preferably the catalyst incorporated by reference supra. Preferably, the catalyst contains from about 2% to about 40% by weight of active metal, a total pore volume of from about 0.3 to about 1.5 cc/g, a total surface area of from about 200 to about 450 m.sup.2/g, and an average pore diameter of at least 50 angstroms.

[0049] With respect to the active metal, referred to supra, metals from Group VI, VII or VIIIB are preferred, and may include one or more of Co, Ni, W, and Mo. While it is not required to do so, the catalysts are generally incorporated on a support, such as alumina, silica, a zeolite or a zeolite modified by, e.g., steam, ammonia, acid washing and/or insertion of transition metals into its structure. The zeolite, if used, may have FAU, MOR, BEA, or MFI topology.

[0050] Concurrent with the hydrocracking of the DAO and the delayed coking, the asphalt portion of the crude oil is gasified in a gasification chamber, e.g., a membrane wall type reactor, preferably at a temperature of from about 900 C. to about 1700 C., and a pressure of from about 20 bars to about 100 bars. Gasification takes place in the presence of an O.sub.2 containing gas, which may be, e.g., pure O.sub.2 or more preferably, air. Means may be provided to control the amounts of asphalt and oxygen entering the gasification reactor. Such means are well known to the skilled artisan and need not reiterated here. It is preferred to control the amounts of asphalt and O.sub.2, so that a stoichiometric balance permitting partial combustion ensues. This can be determined via determining the hydrocarbon content of the crude oil, such as was done in the example, supra. Preferably, the amounts are selected such that the oxygen:carbon ratio ranges from about 0.2:1.0 to about 5:0.1 by weight. Any coke produced in the delayed coking step discussed above may be gasified to produce hydrogen.

[0051] Optionally, steam may be added to the gasification chamber. When it is, it too is added in an amount based upon the carbon content of the crude oil, and is preferably presented at a ratio of from about 0.1:1.0 to about 100:1.0 by weight. Gasification results in a product sometimes referred to as syngas consisting essentially of hydrogen and carbon monoxide. In one embodiment of the invention, the syngas produced by gasification is transmitted to a water gas shift reaction chamber and treated to produce H.sub.2 and CO.sub.2, after which H.sub.2 is separated. The resulting, pure H.sub.2 may be channeled to the hydrocracking reaction.

[0052] The process by which the syngas is treated may include treatment at a temperature of from about 150 C. to about 400 C., and a pressure of from about 1 to about 60 bars.

[0053] As was seen, supra, gas content can be measured at any point in the process described here. Hence, following measurement of CO content in the syngas, water can be added to the reaction chamber, preferably at a molar ratio with CO of from about 3:1 to about 5:1.

[0054] Other facets of the invention will be clear to the skilled artisan and need not be reiterated here.

[0055] The terms and expression which have been employed are used as terms of description and not of limitation, and there is no intention in the use of such terms and expression of excluding any equivalents of the features shown and described or portions thereof, it being recognized that various modifications are possible within the scope of the invention.