Mineral oils: processes and products – Chemical conversion of hydrocarbons – With preliminary treatment of feed
Reexamination Certificate
2000-03-24
2002-09-10
Dang, Thuan D. (Department: 1764)
Mineral oils: processes and products
Chemical conversion of hydrocarbons
With preliminary treatment of feed
C208S058000, C208S210000
Reexamination Certificate
active
06447671
ABSTRACT:
The present invention relates to refining and converting heavy hydrocarbon fractions also comprising sulphur-containing impurities. More particularly, it relates to a process for converting at least a portion of a hydrocarbon feed, for example a vacuum residue obtained from straight run distillation of a crude oil into good quality light gasoline and gas oil fractions and to a heavier product which can be used as a feed for catalytic cracking in a fluidised bed catalytic cracking unit comprising a double regeneration system and optionally a system for cooling the catalyst in the regeneration step. The present invention also relates to a process for producing gasoline and/or gas oil comprising at least one fluidised bed catalytic cracking step.
One aim of the present invention is to produce readily upgradeable lighter fractions such as middle distillates (engine fuel: gasoline and gas oil) and base stock from certain particular hydrocarbon fractions which will be described in more detail below, by partial conversion of those fractions.
Within the context of the present invention, the conversion of the feed to lighter fractions is normally in the range 10% to 75% or even 100% if the unconverted heavy fraction is recycled, usually in the range 25% to 60%, or limited to about 50%.
Feeds which can be treated by the process of the present invention are atmospheric residues or straight run vacuum residues, deasphalted residues, residues from a conversion process such as those from coking, fixed bed hydroconversion such as those from HYVAHL® processes for treating heavy hydrocarbons developed by the Applicant, or heavy hydrocarbon hydrotreatment processes carried out in an ebullated bed such as those from H-OIL® processes, or solvent deasphalted oils, for example using propane, butane or pentane, or asphalts normally originating from deasphalting straight run vacuum residues or vacuum residues from H-OIL® or HYVAHL® processes diluted by hydrocarbon fraction or a mixture of hydrocarbon fractions selected from the group formed by a light cycle oil (LCO), a heavy cycle oil (HCO), a decanted oil (DO), a slurry and gas oil fractions in particular those obtained by vacuum distillation known as vacuum gas oil (VGO). The feeds can also be formed by mixing those various fractions in any proportions, in particular atmospheric residues and vacuum residues. They can also contain gas oil cuts and heavy gas oil cuts originating from catalytic cracking, generally with a distillation range of about 150° C. to about 370° C. or 600° C. or more than 600° C. They can also contain aromatic extracts obtained from manufacturing lubricating oils. In accordance with the present invention, the feeds which can be treated are preferably atmospheric residues or vacuum residues, or mixtures of such residues.
The aim of the present invention is to produce good quality products particularly with a low sulphur content under relatively low pressure conditions, so as to limit the cost of plant. This process can produce a gasoline type engine fuel containing less than 100 ppm by weight of sulphur thus satisfying the most strict regulations governing sulphur content for this type of fuel, from a feed which may contain more than 3% by weight of sulphur. Similarly, and this is of particular importance, a diesel type engine fuel is obtained with a sulphur content of less than 500 ppm and a residue with an initial boiling point of about 370° C., for example, which can be sent as a feed or part of a feed to a residue catalytic cracking step such as a double regeneration step.
The prior art includes descriptions, in particular in United States patents U.S. Pat. Nos. 4,344,840 and 4,457,829, of processes for treating heavy hydrocarbon feeds comprising a first treatment step carried out-in the presence of hydrogen in a reactor containing an ebullated catalyst bed followed by a second fixed bed hydrotreatment step. Those descriptions illustrate the case of fixed bed treatment, in the second step, of a light gas fraction from the product from the first step. It has now been discovered, and this forms one of the aspects of the present invention, that it is possible to use a second step to treat either the whole of the product from the first ebullated bed conversion step or a liquid fraction from this step by recovering the gas fraction converted in the first step under favourable conditions leading to good stability of the system as a whole and to improved middle distillate selectivity. There are other processes for treating heavy hydrocarbon fractions. Thus the Applicant's French, United States and European patents FR-A-2 480 7773, U.S. Pat. No. 4,391,700, FR-A-2 480 774, EP-A-0 113,283, EP-A-0 113 284 and EP-A-0 297 950 describe processes for converting heavy feeds comprising a thermal conversion step, usually termed the hydrovisbreaking step and one or more catalytic steps. Those processes have the disadvantage of forming, in the thermal conversion step, a large quantity of olefinic compounds which then risk clogging the catalyst used in a subsequent step and accelerate its deactivation. A process is also known wherein moving bed treatment is followed by a step for treating the effluent leaving the moving bed in a fixed bed reactor. This type of process is, for example, described by SHELL in the article entitled “The SHELL residue hydroconversion process: development and achievements” presented at the ACS 213
th
National Meeting, San Francisco, Apr. 13-17, 1997, or by the OCR process from CHEVRON using a counter-current moving bed described in the article entitled “On line catalyst replacement, OCR” published in the Oil and Gas Journal, Oct. 12, 1992, pages 52 to 54. Processes from the Institut Francais du Pétrole which were, for example, presented at the NPRA annual meeting, Mar. 17-19, 1991 can also be cited, which use either moving beds or guard reactors in parallel (swing reactors). All of those processes have the drawback of residue conversions which are limited because of the moving bed technology itself whereby the average reaction temperatures reached are not as high as in processes using an ebullated bed.
In its broadest sense, the present invention is defined as a process for converting a hydrocarbon feed containing at least a hydrocarbon fraction with a sulphur content of at least 0.1% by weight, normally at least 2% and usually at least 4% by weight, and an initial boiling point of at least 340° C., normally at least 500° C., and an end point of at least 440° C., usually at least 600° C., and which can be more than 700° C., characterized in that it comprises the following steps:
a) treating said hydrocarbon feed in a section for treatment carried out in the presence of hydrogen, said section comprising at least one three-phase reactor, containing at least one hydroconversion catalyst, wherein the mineral support is at least partially amorphous, in an ebullated bed, operating in liquid and gas upflow mode, said reactor comprising at least one means (
17
) for withdrawing catalyst from said reactor located close to the reactor bottom and at least one means (
16
) for supplying fresh catalyst to said reactor located close to the top of said reactor;
b) sending at least a portion, usually the whole, of the effluent from step a) to a section for eliminating catalyst particles contained in said effluent, said section comprising at least one means for eliminating said solid particles and at least one means for recovering an effluent containing fewer solid particles than the effluent from step a);
c) sending at least a portion, usually the whole, of the effluent from step b) to a treatment section, said treatment being carried out in the presence of hydrogen and optionally a fraction of hydrocarbons added to the effluent from step b), said section comprising at least one reactor containing at least one fixed bed hydrotreatment catalyst wherein the mineral support is at least partially amorphous, under conditions enabling an effluent to be obtained with a reduced sulphur content and a high middle distillate content.
Us
Duplan Jean-Luc
Kressmann Stephane
Morel Frederic
Dang Thuan D.
Institut Francais du Pe'trole
Millen White Zelano & Branigan P.C.
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