Mineral oils: processes and products – Chemical conversion of hydrocarbons – Plural serial stages of chemical conversion
Reexamination Certificate
1999-03-22
2001-08-21
Myers, Helane E. (Department: 1764)
Mineral oils: processes and products
Chemical conversion of hydrocarbons
Plural serial stages of chemical conversion
C208S059000
Reexamination Certificate
active
06277270
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATION
This application is related to applicants concurrently filed application Attorney Docket No. Pet-1745, entitled “Process For Converting Heavy Petroleum Fractions That Comprise A Distillation Stage”, Ebullated-Bed Hydroconversion Stages Of The Vacuum Distillate, And A Vacuum Residue And A Catalytic Cracking Stage, based on French Application 98/03.655 filed Mar. 23, 1998.
This invention relates to the refining and conversion of heavy hydrocarbon fractions that contain, among other things, sulfur-containing impurities. It relates more particularly to a process that makes it possible to convert, at least partly, at relatively low pressure a hydrocarbon feedstock, for example an atmospheric residue that is obtained by direct distillation of a crude into light gasoline and gas oil fractions of good quality and into a heavier product that is used as a feedstock for catalytic cracking in a fluidized-bed catalytic cracking unit that comprises a double regeneration system and optionally a system for cooling the catalyst at the level of regeneration. In one of these aspects, this invention also relates to a process for the production of gasoline and/or gas oil that comprises at least one fluidized-bed catalytic cracking stage.
One of the objectives of this invention consists in producing from a certain special fraction hydrocarbons, which will be specified in the description below, by partial conversion of said fractions of lighter fractions that are easily upgraded, such as engine fuels, gasoline, and gas oil.
Within the framework of this invention, the conversion of the lighter fraction feedstock is usually between 20 and 75% and most often between 25 and 60% and even limited to about 50%.
The feedstocks that are treated within the framework of this invention are atmospheric residues of direct distillation. These feedstocks are usually hydrocarbon fractions that have a sulfur content of at least 0.5%, often at least 1%, and very often at least 2% by weight, and an initial boiling point of at least 300° C., often at least 360° C., and most often at least 370° C., and a final boiling point of at least 500° C., often at least 550° C., and can go beyond 600° C. and even 700° C.
The object of this invention is to obtain a product with a low sulfur content under conditions in particular of relatively low pressure in order to limit the necessary investment cost. This process makes it possible to obtain a gasoline-type engine fuel, a typical engine fuel, and a residue whose initial boiling point is, for example, about 370° C., which is sent as a feedstock or as a portion of feedstock into a catalytic cracking residue stage such as a double regeneration reactor.
In its broader form, this invention is defined as a process for converting a hydrocarbon fraction that contains basically the atmospheric residue of the direct distillation of a crude, characterized in that it comprises the following stages: (the numbers in parentheses refer to the FIGURE):
a) Feedstock (
1
) that contains hydrocarbon is sent to a vacuum distillation zone (
2
) from which a vacuum distillate [DSV(
3
)] and a vacuum residue [RSV(
4
)] are recovered and which most often has an initial boiling point of at least about 300° C. and often at least about 350° C. and even at least about 370° C.
b) At least a portion of the vacuum distillate that is obtained in stage a) is treated in the presence of hydrogen in at least one hydrotreatment section (
5
) that comprises at least one reactor that contains at least one fixed bed of hydrotreatment catalyst that preferably has a strong hydrodesulfurizing activity, under conditions that make it possible to obtain a liquid feedstock (
6
) with low contents of Conradson carbon, metals, sulfur, and most often nitrogen as well.
c) At least a portion of the vacuum residue that is obtained in stage a) is treated in at least one hydroconversion section (
7
) in the presence of hydrogen, whereby said section comprises at least one triphase reactor, contains at least one ebullated-bed hydroconversion catalyst, and operates generally with a rising flow of liquid and gas, whereby said reactor comprises at least one means of drawing off the catalyst to the outside of said reactor that is located close to the bottom of the reactor and at least one means of make-up for fresh catalyst in said reactor that is located close to the top of said reactor, under conditions that make it possible to obtain a liquid feedstock (
8
) with low contents of Conradson carbon, metals, and sulfur.
d) At least a portion of the hydrotreated liquid effluent that is obtained from stage b) is sent to an atmospheric distillation zone from which are recovered an atmospheric distillate (
10
) and an atmospheric residue that most often has an initial boiling point of at least about 300° C. and often at least about 350° C., or at least about 370° C.
e) At least a portion of the hydroconverted liquid effluent that is obtained from stage c) is sent to an atmospheric distillation zone from which are recovered an atmospheric distillate (
12
) and an atmospheric residue (
13
) that most often has an initial boiling point of at least about 300° C. and often at least about 350° C. and even of at least about 370° C., and optionally
f) At least a portion of the atmospheric residue that is obtained in stage d) is mixed with at least a portion of the atmospheric residue that is obtained in stage e), and this mixture (
14
) is sent into a catalytic cracking residue section (
15
) in which it is treated under conditions that make it possible to obtain a gas fraction (
16
), a fuel fraction (
17
) that comprises a gasoline fraction and a gas oil fraction (
18
), and a slurry fraction (
19
). The quantity of atmospheric residue that is obtained in stage d) and that is sent in a mixture with the atmospheric residue of stage e) into catalytic cracking stage f) should be sufficient to ensure that this mixture preferably has a Conradson carbon that is less than or equal to 10 and often less than or equal to 8.
The treatment section of stage c) comprises at least one reactor, but it is often advantageous to use a treatment section that comprises several reactors. In a preferred embodiment, this section will comprise at least two reactors that are arranged in series and often between 2 and 6 reactors that are arranged in series. This section most often comprises two to four reactors that are arranged in series.
The framework of this invention would not be exceeded by including one or more reactors that each comprise, for example, at least one fixed catalyst bed, before the ebullated-bed treatment section of stage c) and before the hydrotreatment section of stage b). Some of these reactors can be arranged in series, while others that form what one skilled in the art calls guard reactors can be arranged in parallel and operate, for example, alternately. Alternate operation is defined here as an operation in which while one or more reactors are operating, the other reactor or series of reactors is isolated, and the catalyst beds that they contain are being regenerated. The use of such an arrangement that comprises at least one reactor that contains at least one fixed catalyst bed before the treatment section of a ebullated bed is not necessarily a preferred embodiment of this invention, however.
The treatment section of stage b) comprises at least one reactor, but it is often advantageous to use a treatment section that comprises several reactors, of which some are arranged in series, whereas others that form what one skilled in the art calls guard reactors can be arranged in parallel and operate, for example, alternately. Alternate operation is defined here as an operation in which while one or more reactors are operating, the other reactor or series of reactors is isolated, and the catalyst beds that they contain are being regenerated.
Hydroconversion section (c) comprises at least one reactor.
In a preferred embodiment, this section will comprise at least two reactors that are arranged in s
Billon Alain
Duplan Jean-Luc
Kressmann Stephane
Morel Frederic
Institut Francais du Pe'trole
Millen White Zelano & Branigan P.C.
Myers Helane E.
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