Mineral oils: processes and products – Chemical conversion of hydrocarbons – Cracking
Reexamination Certificate
1999-07-16
2001-02-20
Griffin, Walter D. (Department: 1764)
Mineral oils: processes and products
Chemical conversion of hydrocarbons
Cracking
C208S126000, C208S127000
Reexamination Certificate
active
06190537
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to oil refinement and more particularly to methods for producing fuel distillates from oil residual stock by hydrogen or thermal cracking using donor solvent processes.
The evolution of oil processing technology poses a problem of a more profound oil refinement, which cannot be solved without extensively implementing the methods for secondary treatment of the oil residual stock, such as black oil, tar and heavy hydrocarbon oils (malthas), containing large concentrations of heavy metals, primarily vanadium and nickel.
BACKGROUND OF THE INVENTION
As for now, one of the most prospective ways of solving the above problem is to carry out simultaneous thermal cracking of oil residues mixed with coal, wherein coal is taken in the amount of 5-30 percent with respect to oil mass (U.S. Pat. No. 4,544,479, 1985; RU, A, 2009166, 1994).
The prior art method includes subjecting the mixture to a light thermal cracking (visbreaking), the main product of which is heavy oil stock with a reduced concentration of metals.
The stock and its distillates can be converted to light oil by catalytic cracking.
The prior art method, however, suffers a number of problems. A relatively low demetalization level provided by this method does not entirely eliminate the problems which arise at further catalytic cracking of the process product, as even in the case of employment of modern metal-resistant catalysts their consumption should be high which adversely affects the cost efficiency of the prior art method.
Another prior art used to solve the aforementioned problem is a method of thermal hydrogen cracking of heavy oil residues, which is referred to in literature as the Aurabon-process (Edward G. Haude, Gregory G. Ionompson, and Robert E. Denny, The Aurabon process: a valuable tool for heavy oil conversion, presented at the AOSTRA Conference, Edmonton, Alberta, Canada, Jun. 6-7, 1985). The advantage of this process is its technological flexibility: modification of the process conditions (temperature, pressure, contact time, etc.) allows the conversion degree and the yield to be varied. Under the most stringent conditions of the Aurabon process, the treatment of black oil from Voskan oil yields, in percentage by mass: gas 5.6, gasoline 4, diesel distillate 14, vacuum gas oil 65, residue 13. Gasoline and diesel distillate are used for further refinement to produce fuel components.
A complicated and yet unsolved problem with the thermal hydrogen cracking is the possibility of coke deposition on the apparatus walls, requiring a periodic stopping of the process and adversely affecting its technical and economical properties.
Most closely approaching the present invention is a method of producing fuel distillates from oil residual stock, including mixing the oil residual stock with sapropelite and a liquid aromatic additive, subjecting the resulting mixture to hydrogen or thermal cracking, and extracting desired products. (RU, A, 2057786, 1996; RU, A, 2076891, 1997). In the prior art method, the thermal or hydrogen cracking is carried out on a mixture containing a heavy oil stock (tars, mixtures of West-Siberian oils, oils from Romashka and Ukhta fields and heavy oil from Bouzatchi field in Mangyshlak), sapropelite (Leningrad or Baltic sulfurous shale or Kuzbass sapromixite) in the amount of 1 to 10 percent by mass, and shale oil or its fraction boiling at 220-340° C. in the amount of 1 to 10 percent by mass at increased temperature and pressure, with subsequent extraction of fuel distillates. The yield of fuel distillates is 56-60 percent by mass with respect to the feed stock after being subjected to thermal cracking and 90 percent after being subjected to hydrogen cracking. Using the hydrofining process, the thermal and hydrogen cracking distillates may be refined to light motor fuels, including motor gasoline and diesel fuel.
The problem with the prior art method is the employment of tetralin or alkyl derivatives thereof as the aromatic additive. Liquid products containing tetralin or alkyl derivatives thereof and their mixtures with other hydrocarbons are produced by hydrogenating technical products containing condensed aromatic hydrocarbons, mainly naphthalene and alkyl derivatives thereof. The process of producing tetralin and its alkyl derivatives is quite costly, consequently, the final product is relatively expensive also. The high price of tetralin hinders the employment of the prior art processes in the oil processing industry.
SUMMARY OF THE INVENTION
It is an object of the present invention to improve efficiency of a method for producing fuel distillates and to reduce the final product cost.
The present invention allows the elimination of employing tetralin or its alkyl derivatives in the process, while the yield of fuel distillates is maintained and even increased.
The above technical result is attained by a method for producing fuel distillates from oil residual stock, including mixing the oil residual stock with sapropelite and a liquid aromatic additive, subjecting the resulting mixture to hydrogen or thermal cracking, and extracting desired products, wherein prior to the hydrogen or thermal cracking the mixture is subjected to at least double-stage homogenization in an activator at a temperature between 85 and 105° C., the liquid aromatic additive being a fraction of hydrogenated thermal or hydrogen cracking products boiling at 300-400° C., taken in the amount of 1-5 percent by mass with respect to the oil residual stock.
At the double-stage homogenization in the activator, the mixture can be maintained at a temperature of 85-95° C. at a first stage and 95-105° C. at a second stage.
The mixture can be also subjected to a three-stage homogenization in the activator at a temperature of 85-95° C. at the first stage, 95-105° C. at the second stage and 105-135° C. at the third stage.
In accordance with the invention, a heavy oil stock (black oil, tar) is sequentially mixed with a liquid product and sapropelite. Sapropelite is pre-crushed to particles of a size under 0.1 mm, preferably less than 0.8 mm. Sapropelite can be crushed even to the finer particles as small as 50 to 100 &mgr;m. The resulting mixture is subjected to a single-, double- or three-stage homogenization in an activator at a temperature between 85 and 135° C. In the homogenization process, the feed stock is partially activated both mechanically and chemically, the additives being evenly distributed throughout the feed stock volume. The size of additive particles (0.3-0.5 nm) matches the size of oil stock molecules (0.4-0.7 nm). This circumstance is of paramount importance in provision of the optimum contact between the additives and the oil stock molecules. After being subjected to the above treatment, the feed stock forms the stable mixture which does not segregate for a long time.
When the homogenization is carried out in an activator at a temperature under 85° C., the efficiency of mechanical and chemical activation of the feed stock noticeably worsens and necessitates the extension of the treatment stages to attain the comparable results. It is inadvisable to raise the homogenization temperature above 135° C. as this requires the considerable increase of power consumption and makes the final product produced by this method more expensive.
An activator in the present invention is a conventional apparatus used in petrochemical industry for similar purposes.
The concept of thermal cracking or hydrogen cracking is used herein in its conventional meaning and refers to contacting a feed stock to be cracked with hydrogen in the amount of 500 to 2000 volumes of hydrogen or hydrogen-containing gas under the normal conditions (T=0° C., P=0.1013 MPa) per a volume of liquid stock at a pressure of 4.0-15.0 MPa, a space velocity of 1-3 h
−1
(conditional contact time—20-90 min) and a temperature between 390 and 440° C.
The reaction equipment generally used in industry includes pipe kilns or pipe kilns with an extension reaction chamber. In the laboratory conditions, the
Efimenkov Valentin Dmitrievich
Julin Mikhail Konstantinovich
Kanataev Juri Alekseevich
Ruzhnikov Evgeny Aleksandrovich
Graybeal Jackson Hale LLP
Griffin Walter D.
Zakrytoe Aktsionernoye Obschestove “Panjsher- Holding”
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