Mineral oils: processes and products – Chemical conversion of hydrocarbons – Plural serial stages of chemical conversion
Reexamination Certificate
1999-08-05
2001-05-22
Myers, Helane (Department: 1764)
Mineral oils: processes and products
Chemical conversion of hydrocarbons
Plural serial stages of chemical conversion
C208S058000, C208S089000
Reexamination Certificate
active
06235190
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a novel hydrocarbon conversion process. Specifically the invention relates to an integrated petroleum refining process comprising sequential feed hydrotreating and hydrocracking reaction zones.
RELATED ART
Hydrotreating processes are used commercially in a large number of petroleum refineries. They are used to process a variety of feeds ranging from naphthas to very heavy residual crude oil fractions. In general a hydrotreating process improves the quality of the hydrocarbonaceous feed by increasing the hydrogen to carbon ratio of the feed compounds and/or by removing sulfur and nitrogen. The significant economic utility of hydrotreating processes has resulted in a large amount of developmental effort being devoted to the improvement of these processes and to the development of highly stable and active catalysts for use in these processes.
Hydroprocessing to effect the hydrogenation of aromatic compounds boiling in the diesel fuel or kerosene boiling ranges is a well established commercial process. A study of the conditions useful in the saturation of diesel fuel aromatics, the effects of varying these conditions on product properties and other factors in using a specific commercially available hydrogenation catalyst are presented in an article at page 47 of the May 29, 1989 edition of the
Oil and Gas Journal.
A second article on the production of low aromatic hydrocarbon diesel fuel is presented at page 109 of the May 7, 1990 edition of the
Oil and Gas Journal
. These articles are incorporated herein by reference for their teaching in regard to hydrogenation practices.
U.S. Pat. No. 5,389,595 issued to H. D. Simpson et al. describes a modern hydrotreating catalyst suitable for the denitrogenation and desulfurization of a gas oil feed stream to a hydrocracking process.
The very significant economic utility of the hydrocracking process has also resulted in a large developmental effort being devoted to the improvement of the process and to the development of better catalysts for use in the process. A general review and classification of different hydrocracking process flow schemes and a description of hydrocracking catalysts is provided at pages 174-183 of the book entitled,
Hydrocracking Science and Technology
authored by Julius Scherzer and A. J. Gruia published in 1996 by Marcel Dekker, Inc.
FIGS. 10.2
,
10
.
3
and
10
.
5
show hydrotreating reactors upstream of the hydrocracking reactor.
U.S. Pat. No. 3,505,208 issued to R. P. Vaell describes an integrated hydrotreating/hydrocracking process. The process flow illustrates hydrotreating the feed to the two downstream hydrocracking reaction zones. The hydrotreating reactor contains two beds of hydrotreating catalyst. This reference illustrates a two-stage hydrocracking arrangement with only recycled unconverted hydrocarbons and recycle hydrogen-rich gas being charged to the second reactor.
BRIEF SUMMARY OF THE INVENTION
The subject invention is the discovery that a unique arrangement of hydrotreating catalysts in an upstream hydrotreating zone results in improved product quality for specific distillate products recovered from a downstream hydrocracking zone. Specifically, changing to a stacked configuration of hydrotreating catalysts having a more active catalyst located after a less active catalyst results in an improvement in the smoke point of the jet fuel recovered from the hydrocracking zone.
One broad embodiment of the invention may be characterized as a hydrocracking process which comprises passing hydrogen and a feed stream comprising hydrocarbonaceous compounds into a first hydrotreating zone containing a first hydrotreating catalyst and operated at hydrotreating conditions and producing a first hydrotreating zone effluent stream; passing the first hydrotreating zone effluent into a second hydrotreating zone operated at hydrotreating conditions and containing a second hydrotreating catalyst, which second hydrotreating catalyst has a relative activity at least five percent greater than the first hydrotreating catalyst; and producing a second hydrotreating zone effluent stream; passing the second hydrotreating effluent stream and additional hydrogen into a hydrocracking zone containing a hydrocracking catalyst and maintained at hydrocracking conditions, and producing a hydrocracking zone effluent stream; passing the hydrocracking zone effluent stream into a vapor-liquid separation zone which separates the entering compounds into a hydrogen rich recycle gas stream and a first liquid process stream; and, passing the first liquid process stream into a product recovery zone comprising a fractionation column, and recovering a jet fuel boiling range product distillate hydrocarbon stream from the first liquid stream.
REFERENCES:
patent: 3505208 (1970-04-01), Vaell
patent: 5389595 (1995-02-01), Simpson et al.
Nash, Richard M. “Refining/Gas Processing Technology”.Oil and Gas JournalMay 29, 1989:47-56.
Suchanek, Arthur J. “Catalytic routes to low-aromatics diesel look promising.”Oil and Gas JournalMay 7, 1990: 109-119.
Scherzer, Julius and A.J. Gruia.Hydrocracking Science and Technology. New York: Marcel Dekker, Inc., 1996: 174-183.
J. Scherzer,et al, pp174-, 1996.
Myers Helane
Spears, Jr. John F.
Tolomei John G.
UOP LLC
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