CA2605056C - Deasphalted oil conversion process - Google Patents

Abstract

The invention concerns a conversion process of a heavy load with a boiling temperature greater than 340°C for at least 80 wt% of the load, a Conradson carbon content of at least 5 wt%, an asphaltene content of at least 1 wt%, a sulphur content of at least 0.5 wt%, a metals content of at least 20 ppm, process in which: - the said load is subjected to deasphalting and a deasphalted oil containing less than 1 wt% of asphaltenes is obtained at least a part of the said oil, and preferably its entirety, is directly subjected to hydroconversion in the presence of a supported or dispersed catalyst and the effluent obtained is distilled to separate a residue the entirety of the said residue is recycled with the load during deasphalting.

Description

PROCESS FOR CONVERTING DESASPHALIZED OIL
The invention relates to a process for the hydroconversion of petroleum feeds heavy, by example of residues such as atmospheric residue (AR) or vacuum residue (VR), for produce gasolines, gas oils, vacuum gas oils.
A conventional VR / AR conversion process chain consists of a step solvent deasphalting (SDA) followed by a step of hydroconversion of the DAO (oil deasphalted) then distillation to turn it into high-grade products added value (gasoline, middle distillates, VGO: ie vacuum gas oil, vacuum residue).
The disadvantage of this type of scheme is that it is virtually impossible to complete a total conversion of the DAO into converted products, the residue being discharged out of unit. For increase conversion, it has been recommended to recycle hydroconversion residue hydroconversion which has been separated by distillation. This approach is limited because of the very refractory nature of CAD at total hydroconversion, and more than it is heavy DAO, that is, extracted with solvents ranging from C4 (butane) to C6 (hexane). he It is therefore not possible to arrive at a total conversion of the DAOs into a unit hydroconversion operating in liquid recycling mode.
We have now looked for a process for the production of gasoline and diesel with good yields and good qualities by a simple and economical process, in particular with recycling of the CAD until extinction, which overcomes the disadvantages cited above.
The invention relates to a method in which the DAO is converted completely until his total extinction by recycling the unconverted residue at the very entrance of the unit of deasphalting. The asphaltenes produced in the hydroconversion stage are then to be eliminated in the SDA unit and end up in the asphalt phase, although that the DAO
recycled which is virtually free of asphaltene will enter the unit hydroconversion mixed with the DAO "straight-run" (SR), and will crack in the unit hydroconversion however with a conversion rate slightly lower than the DAO SR.
Thus with a conversion per pass of recycled DAO slightly lower than that of DAO SR, we arrive after a few passages to a total conversion of the DAO
in products with high added value. It appears that the asphalt yield only increases little compared to the pattern without recycling, due to the accumulation of weak quantities asphaltenes formed in the hydroconversion stage.

2 More specifically, the invention relates to a charge conversion method heavy product with a boiling point above 340 C for at least 80% by weight of the load, a Conradson carbon content of at least 5% by weight, an asphaltenes content of at least 1% by weight, a sulfur content of at least 0.5% wt, a metal content of at least 20 ppm, in which process:
- said charge is subjected to a deasphalting and a deasphalted oil containing less than 1% by weight of asphaltenes is obtained, at least a part of said oil is subjected directly to a hydroconversion in the presence of a supported or dispersed catalyst and the effluent obtained is distilled to separate a residue, the step of hydroconversion operating in a bubbling bed with a conversion passes at least 60% wt or in moving bed with a conversion greater than or equal to 20% by weight and less than 50% by weight or in slurry with a conversion of at least 50% wt, and - All of said residue is recycled with the deasphalting load.
The invention is explained with reference to FIG.
The charge is usually of the residue type. It usually has a content Conradson carbon of at least 5%) / opds and generally at least 10% wt.
content asphaltene (standard 1P143 / C7) by at least 1%, often at least 2% and very often from less than 5% wt, and may even equal or exceed 24% wt. Their sulfur content is generally at least 0.5%, often at least 1% and often at least 2% or even up to 4% or even 10% wt. The quantities of metals they contain are generally at least 20 ppm, often at least 50 ppm, and typically at less than 100 ppm or at least 200 ppm wt.

2a Such feedstocks are crude oils that are partially topped, e.g.
unencumbered, atmospheric residues, vacuum residues, atmospheric residues or under vacuum derived from the distillation of crude oils (SR), or from a process of primary conversion atmospheric or vacuum residues (such as visbreaking, hydroconversion ...), or still atmospheric or vacuum residues from crude oils conventional light to medium to heavy (eg Middle East, Urals, West African, ..) or extra gross heavy having eg. an API less than 15 (raw from Venezuela, Canada ...).
It may also include coals or cokes advantageously introduced in suspension.

3 The charges are usually characterized by a boiling temperature better than 340 C for at least 80% by weight of the filler, and preferably for at least less 90%
the load. The method is particularly applicable to heavy loads having a boiling point above 500 ° C or 540 ° C for at least 80%
wd of the charge or, preferably for at least 90% of the charge. They present generally (fresh charges) a viscosity of less than 100,000 cSt at 100 C, even less than 40000cSt and preferably less than 20,000 cSt at 100 C.
have to typically be converted to produce finished products such as the diesel, gasoline and LPG, lower boiling temperature.
The load arriving via line 1 is sent to the deasphalting unit 2. At this charge is added by the conduct 111th residue from the distillation which will be described later.
The step of deasphalting with a solvent is carried out in conditions well known to those skilled in the art.
For example, methods such as Solvahl, Rose, etc. can be used.
Deasphalting is usually carried out at a temperature of 60 to 250 ° C
with at less a hydrocarbon solvent having from 3 to 7 carbon atoms added with at least one additive. Usable solvents and additives are widely described.
These are as previously indicated, for example, 04 to 06, and more especially 05 or 06. It is also possible and advantageous to perform the recovery of solvent according to the opticritic process that is to say using a solvent under conditions no Supercritical. This process makes it possible in particular to improve significantly the global economy of the process. This deasphalting can be done in a mixer-settler or in extraction column.
In the context of the present invention, the technique using least one extraction column and preferably one. Advantageously, as in the Solvahl process with a single extraction column, the ratios solvent / incoming charge into SDA are low, between 4/1 and 6/1. This allows for excellent metal mining and asphaltenes, to have only very small amounts of solvent in the DAO. The unit of

4 deasphalting produces a virtually free DAO (deasphalted oil) asphaltenes and an asphalt (pipe 13) concentrating most of the impurities of the residue and who is withdrawn. We have not shown the management of the solvent which is known to man business. The CAD yield can range from less than 50 wt% to more than 90 wt%.
DAO has an asphaltenes content reduced to minus 1% by weight in general (measured C7), preferably less than 0.5%, most often less than 0.05% (process Solvent by ex) and even more preferably less than 0.3% wt measured in C5 insoluble and less than 0.05% by weight measured in insoluble C7 (Solvahl process for example).
At least a portion of the DAO, and preferably all, is sent in a unit hydroconversion 3.
The hydroconversion stage therefore allows a partial conversion of the residue into more products light as the load (gas, gasoline, middle distillates, vacuum distillates VGO) leaving a certain amount of unconverted residue; it can be implemented according to various processes, such as the following commercial processes:
- hydroconversion processes in fixed bed preferably followed by a unit of visbreaking (Hyvahl, preferably followed by a visbreaking ("visbreaking"), Unibon ..,) that operate with conversions by pass typically less than 50 wt.% but at least 20 wt.
at least 30% wt - hydroconversion processes in a moving bed with semi-continuous catalyst supported which operate with moderate pass conversions typically of less than 50% by weight but at least 20% by weight or at least 30% by weight.
- Bubbling bed processes advantageously operating with semi-booster continued of catalyst (H-Ou, LC-Fining ...) that operate with pass conversions strong, generally at least 60% wt. This type of process is preferred.
- hydroconversion processes in slurry (HDHPLUS, EST ...) which operate with of the generally high pass conversions of at least 50% or more 60% and preferably at least 80% wt.
or their associations.
Bubbling bed processes are preferred.

The conversion is defined as the ratio (/ 0 wt.
charge -% residue in the product) /% residue in the load, for the same load-cutting point product;
typically this cutting point is between 450 and 550 C, and often about 500 VS; in this definition, the residue being the fraction boiling from this point cutting (as

5,500 C +, for example).
For ebullated bed processes, generally at least one catalyst classic hydroconversion. This catalyst is usually a catalyst including a support, generally amorphous, which is preferably an alumina, and at least a metal of the group VIII (eg nickel and / or cobalt), most often in association with at minus a group VIB metal (for example molybdenum). One can for example to employ a catalyst comprising from 0.5 to 10% by weight of nickel and preferably from 1 to at 5% in nickel (expressed as nickel oxide NiO) and from 1 to 30% by weight of molybdenum preferably from 5 to 20% by weight of molybdenum (expressed as molybdenum oxide Mo03) on a support, for example an alumina support. This catalyst is the most often in form extrusion or ball.The mechanical strength of the supports is high for the operating in a bubbling bed.
This stage is usually carried out under an absolute pressure of 5 to 35.degree.
MPa and the more often 10 to 25 MPa at a temperature of about 300 to about 500 C and often approximately 350 to 450 C. The liquid VVH and the hydrogen partial pressure are chosen depending on the characteristics of the load to be processed and the conversion desired. most often the VVH of the liquid is from about 0.1 to about 5 h -1 and preferably from about 0.15 to about 2 h -1. The used catalyst is partly replaced by a catalyst fees according to methods known to those skilled in the art.
In this stage, a catalyst is advantageously used, ensuring at the same time the demetallization and desulphurisation, under conditions allowing to obtain a charge reduced metal, carbon Conradson and sulfur and allowing to get a strong conversion.
This type of bubbling bed process associated with the SDA is therefore particularly advantageous to treat DAOs often containing more than 30 ppm metals.
In fixed bed processes, generally, at least one fixed bed is used of catalyst classic hydroconversion. We usually operate under absolute pressure from 5 to 35

6 MPa and most often 10 to 20 MPa at a temperature of about 300 to 500 C
and often approximately 350 to 450 C. The VVH and the hydrogen partial pressure are chosen according characteristics of the charge to be treated and the desired conversion. The more often the VVH is in the range of about 0.1 to about 5h-1 and preferably about 0.15 to about 2. The amount of hydrogen mixed with the feed is usually about 100 to about 500 normal cubic meters (Nm3) per cubic meter (m3) of load liquid and the more often from about 500 to about 3000 Nm3 / m3.
The ideal catalyst must have a high hydrogenating power so as to achieve a refining deep, and to obtain a substantial lowering of sulfur, Conradson carbon and some asphaltenes content. For example, one of the catalysts described by the applicant in patents EP-B-113297 and EP-B-113284.
Regarding processes operating in slurry, ie in the presence of a phase circulating dispersed catalytic, they usually operate under pressure total of 1--50MPa, preferably 2-30 MPa, with a hydrogen partial pressure ranging from 1 to 50 MPa, preferably 2 to 30 MPa, with a temperature of 300 to 600 C, preference of 400 to 470 C, the contact taking place for a certain time necessary for the conversion of residue, ranging from 5 minutes to 20 hours, preferably between 1 and 10 hours.
The catalysts are well known to those skilled in the art, and are obtained at from the thermal decomposition of catalytic precursors (eg naphthenate molybdenum etc ...).
The effluent obtained at the end of the hydroconversion stage (leaving the driving 4) is distilled in the atmospheric column 5 and it is obtained from gasoline (line 6), from diesel (line 7) and an atmospheric residue (line 8 of fig.1).
Advantageously, the residue is distilled under vacuum (column 9) and is obtained from VGO
(vacuum gas oil by line 10) and a vacuum residue (line 11).
In zone 5 of atmospheric distillation, the conditions are generally chosen from so that the cutting point for the residue is from about 300 to about 400 C and preferably from about 340 to about 380 C. Distillates [petrol fraction (conduct 8), and diesel fraction (line 9)] thus obtained are usually sent to fuel pools correspondents. Before being sent, the diesel produced by the process according to the invention is hydrotreated in a subsequent unit 12, under the operating conditions and with the

7 catalysts usually used and known to those skilled in the art, so as to bring the sulfur content to market specifications, which is less than 10 ppm of sulfur, and to improve the cetane number. Before being sent to the gasoline pool, the essence fraction is usually processed by reforming (not shown in the figure).
Preferably, the atmospheric residue (line 8) is sent for distillation under vacuum.
In zone 9 of vacuum distillation, the conditions are generally chosen from so that the cutting point for the residue is about 450 to 600 C
and the most often about 500 to 550 C. The vacuum distillate (VGO) fraction obtained come out by the line (s) 10 and the vacuum residue through line 11.
The VGO is advantageously sent at least partly in a unit of cracking catalytic 13.
According to the invention, the atmospheric residue or preferably the residue under empty is recycled at least in part, and preferably in whole, in the feed entering into deasphalting.
Thus the total conversion is at least 20% or at least 30% wt, and in the case of the beds at least 60% or even 80%, and in the case of slurry, most often at least 80%.
Example The filler is an extra-heavy vacuum residue of Candian origin. Table below reports the properties of this residue as well as those of the DAO obtained by deasphalting pentane of this residue (Solvahl process):
tab.1 VR DAO
Density 1.07 0.994 Viscosity at 100 C cSt 30640 192.2 Conradson Carbon weight% 21.9 8.5 C7 Asphaltene wt% 14.9 Nickel ppm 137 20 Vanadium ppm 337 35

8 Nitrogen ppm 6000 3249 Sulfur wt / 0 5.4 4.05 This DAO is treated on the one hand in the conventional hydroconversion scheme in bed bubbling followed by atmospheric distillation and distillation vacuum without recycling of the residue under vacuum, and secondly in the scheme according to the invention with recycling all the residue under vacuum to the deasphalting.
Hydroconversion is under the same conditions in the two cases: 10 MPa of hydrogen and 440 ° C.
presence of a NiMo / alumina catalyst. Returns are shown in% wt compared at a starting base 100 of VR (Tab.2).
Tab.2 % Vs. VR feed SDA + HCK SDA + HCK
Without Recycle Recycling Schematic diagram of conventional ______________________ the invention H2S + NH3 3.0 3.0 Gas: 3.6 4.3 Essence: 9.7 11.5 Diesel: 18.5 22.3 VGO: 18.8 22.7 VR 13.0 0.0 DAO
SDA purge 35.0 38.0 Total 101.5 101.8 H2 consumption 1.5 1.8 With the conventional scheme, we obtain interesting yields in converted products but there remains however 13 A vacuum residue which has a very low value. asphalt product represents 35% by weight of the starting vacuum residue.
With the scheme according to the invention with recycling of the unconverted residue in the unit of the amount of asphalt increases slightly to 38% compared to 35%
in the conventional scheme, but on the other hand the yields of light products increase significantly, especially the diesel cut goes from 18.5 "Yopds in the diagram

9 conventional 22.3% yield in the scheme according to the invention. The cup VGO
from 18.8 to 22.7% wt.
This example demonstrates that it is possible, contrary to the preconception what was the man of the trade, to recycle all of the residue under hydroconversion vacuum deasphalted increasing diesel and gasoline yields while maintaining products suitable and without reducing the life of the catalyst, and without it being produces significant amounts of asphalt.
It has been shown here that refractory compounds are eliminated at deasphalting.
The invention thus makes it possible to obtain gasoline and diesel fractions with very high good yields with good qualities of products with an economical process.
Moreover, with the process according to the invention, it has been found that could produce a very good charge for catalytic cracking (FOC) which is the VGO does not not containing of catalytic cracked refractory asphaltenes. So the VGO can be sent directly to the FOC and without pre-treatment.

Claims (5)

1. Process for converting heavy feedstock having a boiling temperature greater than 340 ° C for at least 80% of the carbon Conradson of at least 5 wt%, an asphaltenes content of at least 1 wt%, a sulfur content of at least 0.5% by weight, a metal content of at least 20 ppm, process in which:
- said charge is subjected to a deasphalting and a deasphalted oil containing less than 1% by weight of asphaltenes is obtained, at least a part of said oil is subjected directly to a hydroconversion in the presence of a supported or dispersed catalyst and the effluent obtained is distilled to separate a residue, the step of hydroconversion operating in a bubbling bed with a conversion passes at least 60% wt or in moving bed with a conversion greater than or equal to 20% by weight and less than 50% by weight or in slurry with a conversion of at least 50% wt, and - All of said residue is recycled with the deasphalting load. The process according to claim 1, wherein all of the oil deasphalted is subjected to hydroconversion. 3. A process according to any one of claims 1 and 2, wherein the charge has a boiling point above 540 ° C for less 80% wt. Of the charge and a viscosity of less than 100,000 cSt at 100 ° C. 4. The method of claim 1, wherein the hydroconversion step operates in slurry at a temperature of 400-470 ° C and with a conversion of less 80% wt. The method of claim 1, wherein said charge is directly subject to deasphalting.