CN113906120A

CN113906120A - Olefin production process including hydrotreating, deasphalting, hydrocracking and steam cracking

Info

Publication number: CN113906120A
Application number: CN202080042978.8A
Authority: CN
Inventors: W·魏斯; I·梅德里尼亚克
Original assignee: IFP Energies Nouvelles IFPEN
Current assignee: IFP Energies Nouvelles IFPEN
Priority date: 2019-06-12
Filing date: 2020-06-08
Publication date: 2022-01-07
Anticipated expiration: 2040-06-08
Also published as: TW202113047A; KR20220024420A; FR3097229B1; FR3097229A1; CN113906120B; WO2020249498A1

Abstract

The invention relates to a method for producing olefins from a hydrocarbon feedstock 11 having a sulphur content of at least 0.1 wt.%, an initial boiling point of at least 180 ℃ and a final boiling point of at least 600 ℃.

Description

Olefin production process including hydrotreating, deasphalting, hydrocracking and steam cracking

Technical Field

The present invention relates to a process for the production of olefins from a heavy hydrocarbon fraction whose components include sulphur impurities, metals and asphaltenes.

Prior Art

The development of engines and the gradual electrification of a portion of vehicle inventory has driven the demand for petroleum products to change, with the trend of decreasing the demand for engine fuel. In contrast, the demand for primary petrochemicals, particularly olefins, has grown more permanently. Ethylene and propylene, for example, are highly desirable olefins because they are essential intermediates for many petrochemicals, such as polyethylene or polypropylene. It would therefore be advantageous to further integrate existing refinery sites with petrochemical sites, adapt refinery sites to at least partially produce primary petrochemicals, or design new integrated refinery-petrochemical systems, or design sites that convert most or all of the crude oil into primary petrochemicals.

The main process capable of converting heavy hydrocarbon fractions to olefins in high yield is steam cracking. The production of the desired olefins is accompanied by-products, in particular aromatics and pyrolysis oils, which require purification steps. Furthermore, the selectivity to the desired olefins is strongly dependent on the quality of the feedstock introduced into the steam cracking step. It would therefore be advantageous to find a new process that is capable of producing olefins from heavy hydrocarbon fractions in a more efficient, profitable and process independent manner.

Advantageously, the process of the invention enables to optimize the properties of the fraction introduced into the steam cracking step, thus maximizing the yield of the relevant olefins during the steam cracking step.

In a process for treating heavy hydrocarbon fractions, the hydrotreatment of the residual oil in a fixed bed makes it possible to remove some of the contaminants of the feedstock, in particular metals, sulphur and asphaltenes.

It is also known practice to perform deasphalting operations. Deasphalting enables the separation of an asphaltene-rich fraction of bitumen, known as pitch, from a DeAsphalted Oil fraction with greatly reduced asphaltene content, known as DAO, i.e. "DeAsphalted Oil", thus facilitating its exploitation by catalytic or hydrocracking.

The conversion products, more particularly the heavy fractions obtained from the conversion process, such as deasphalted oils and vacuum distillates, are difficult to treat directly in the steam cracking step. The presence of high levels of naphthenes and aromatics results in a sharp decrease in the yield of associated olefins, an increase in the yield of pyrolysis oil, and increased coking of the tubes of the steam cracking furnace, which is detrimental to operability. It is therefore necessary to enhance the operability of the steam cracking step in order to produce olefins in good yields.

The present invention aims to overcome the above problems and in particular to provide a process which enables flexible production of olefins and optimized production from heavy hydrocarbon fillers to enhance the profitability of the olefin production process.

Accordingly, the applicant has developed a new process for the production of olefins comprising a fixed bed residue hydrotreatment step, a deasphalting step for the production of a DAO fraction and a bituminous fraction, a fixed bed hydrocracking step, an extraction step for the production of a raffinate and an aromatics-rich fraction and a steam cracking step of said raffinate.

The method of the invention has the following advantages:

-the use of the heavy fraction for the production of essential petrochemical intermediates,

production of olefins from heavy fractions in good yield,

-the reduction of the cost of the olefin production,

flexibility of the process, ability to handle all heavy fractions, whatever their origin,

-the sequencing of the hydrotreatment step of the residuum and the deasphalting step so as to be able to convert sufficiently the residual fraction, in particular the asphaltenes,

-limiting coking during said steam cracking step.

Summary of The Invention

The subject of the present invention relates to a process for the production of olefins from a hydrocarbon feedstock 1 having a sulphur content of at least 0.1 wt.%, an initial boiling point of at least 180 ℃ and a final boiling point of at least 600 ℃, said process comprising the following steps:

a) a hydrotreating step carried out in a fixed bed reactor, wherein the heavy hydrocarbon feedstock 1 is contacted with a hydrotreating catalyst in the presence of hydrogen, said step producing an effluent 3;

b) a step of separating the effluent 3 obtained from the hydrotreatment step a) into a gaseous fraction 4, a fraction 11 comprising compounds having a boiling point between 350 and 520 ℃ and a liquid vacuum residue fraction 5 comprising compounds having a boiling point of at least 520 ℃,

c) a deasphalting step by liquid-liquid extraction obtained from the fraction 5 of the vacuum residue of the separation step b), said step c) being carried out with the aid of a solvent 6 or a mixture of solvents, capable of producing, on the one hand, a fraction 7 containing bitumen and, on the other hand, a fraction 8 of deasphalted oil,

d) a step of extracting aromatic hydrocarbons from at least a portion of the deasphalted oil fraction 8 obtained from the deasphalting step c), capable of producing an extract fraction 13 and a raffinate fraction 10,

e) a fixed bed hydrocracking step of at least a portion of fraction 11 obtained from separation step b) and of at least a portion of extract fraction 13 obtained from extraction step d) in the presence of a hydrocracking catalyst, capable of producing an effluent 14,

f) a step of separation of the effluent 14 obtained from the fixed bed hydrocracking step e) into at least one gaseous fraction 15 and at least one liquid fraction 16,

g) the steam cracking step of the raffinate fraction 10 obtained from the extraction step d) and the liquid fraction 16 obtained from the separation step f) comprising compounds having a lowest boiling point of less than 350 ℃ is capable of producing an effluent 17,

h) the separation step of the effluent 17 obtained from the steam cracking step g) is capable of producing at least one fraction 18 containing hydrogen, a fraction 19 containing ethylene, a fraction 20 containing propylene and a fraction 21 containing pyrolysis oil.

In a preferred embodiment, the separation step b) comprises a vacuum distillation capable of producing at least one vacuum distillate fraction 11 and at least one vacuum residue fraction 5.

In a preferred embodiment, the separation step b) comprises, upstream of the vacuum distillation, an atmospheric distillation capable of producing at least one atmospheric distillate fraction 22 and at least one atmospheric residue fraction, said atmospheric residue fraction being sent to said vacuum distillation capable of producing at least one vacuum distillate fraction 11 and at least one vacuum residue fraction 5.

In a preferred embodiment, the residue fraction 5 obtained from step b) is sent in its entirety to the deasphalting step c).

In a preferred embodiment, the solvent 6 used in step c) is a non-polar solvent consisting to an extent of at least 80% by volume of saturated hydrocarbons comprising a carbon number between 3 and 7.

In a preferred embodiment, a portion of the distillate fraction 22 obtained from separation step b) is introduced into the aromatic extraction step d).

In a preferred embodiment, the fraction boiling above 180 ℃ is subjected to an aromatic extraction step d).

In a preferred embodiment, the boiling point of the compounds extracted during step d) is higher than the boiling point of the solvent 6 used.

In a preferred embodiment, the hydrocracking step e) is operated such that the yield of liquid compounds having a boiling point of less than 220 ℃ is more than 50 wt% of the feedstock entering the hydrocracking step e).

In a preferred embodiment, the separation step f) comprises at least one atmospheric distillation capable of producing at least one atmospheric distillate fraction 16 comprising compounds having a boiling point of less than 350 ℃ and a liquid fraction comprising a vacuum distillate comprising compounds having a boiling point of more than 350 ℃.

In a preferred embodiment, the atmospheric distillate fraction 16 and the fraction comprising vacuum distillate are sent to steam cracking step g).

In a preferred embodiment, a portion of the fraction comprising compounds having a boiling point between 80 and 180 ℃ obtained from the separation step b) is introduced into the steam cracking step g).

In a preferred embodiment, the steam cracking step g) is carried out in at least one pyrolysis furnace at a temperature between 700 and 900 ℃ and a pressure between 0.05 and 0.3 MPa for a residence time of less than or equal to 1.0 second.

In a preferred embodiment, the fraction enriched in saturated compounds obtained from the light gas or pyrolysis gasoline from the separation step h) can be recycled to the steam cracking step g).

In a preferred embodiment, the pyrolysis oil fraction 21 is subjected to an additional separation step to obtain a light pyrolysis oil comprising compounds having a boiling point of less than 350 ℃ and a heavy pyrolysis oil comprising compounds having a boiling point of more than 350 ℃. The light pyrolysis oil is injected upstream of the hydrocracking step e) and the heavy pyrolysis oil is injected upstream of the hydrotreating step a) and/or the deasphalting step c).

List of drawings

FIG. 1 represents the sequence of the process of the present invention.

Fig. 2 is a variant of the implementation of the method of the invention shown in fig. 1, illustrated in the example.

Description of the embodiments

It is to be noted that throughout this specification the expressions "between … and …", "less than" or "greater than" are to be understood as including the mentioned limits.

Within the meaning of the present invention, the various embodiments given can be used alone or in combination with one another, without any restriction to these combinations.

In the remainder of the description, reference is made to fig. 1, which illustrates an embodiment of the process for producing olefins from a heavy hydrocarbon feedstock according to the present invention. The elements labeled in fig. 1 are indicated in the remainder of the description to provide a better understanding of the invention, but the invention is not limited to the specific embodiment shown in fig. 1.

As shown in fig. 1, the method of the present invention comprises the steps of:

-a step a) of hydrotreating a heavy hydrocarbon feedstock 1 in the presence of a hydrogen-rich gas 2 in at least one fixed bed reactor comprising a hydrotreating catalyst;

-a separation step b) of the effluent 3 obtained from the hydrotreatment step a), capable of producing at least one hydrogen-containing fraction 4, a liquid fraction 11 containing compounds having a boiling point between 350 and 520 ℃ and a heavy liquid fraction 5 containing compounds having a boiling point higher than 520 ℃;

a deasphalting step c) of fraction 5 obtained from separation step b) as a mixture with a solvent or combination of solvents 6, capable of producing at least one fraction 8 comprising deasphalted oil (DAO) and a fraction 7 containing bitumen;

a step d) of extraction of the fraction 8 comprising deasphalted oil (DAO) obtained from the deasphalting step c) with a solvent or a combination of solvents 9, capable of producing at least one fraction 10 enriched in saturated compounds (raffinate) and a fraction 13 enriched in aromatic compounds (extract);

-a steam cracking step e) of the liquid fraction 11 obtained from the separation step b) in the presence of a hydrogen-rich gas 12 and of an aromatic-rich fraction 13 obtained from the extraction step d), which is carried out in at least one fixed-bed reactor comprising a hydrocracking catalyst;

-a separation step f) of the effluent 14 obtained from the hydrocracking step e), capable of producing at least one hydrogen-containing fraction 15 and a fraction 16 comprising compounds having a boiling point of less than 350 ℃;

-a steam cracking step g) of the raffinate fraction 10 obtained from the extraction step d) and of the fraction 16 containing compounds having a boiling point of less than 350 ℃ obtained from the separation step f);

a separation step h) of the effluent 17 obtained from the steam cracking step g), capable of recovering at least one fraction 18 containing hydrogen, a fraction 19 containing ethylene, a fraction 20 containing propylene and a fraction 21 containing pyrolysis oil.

Fig. 2 presents a variant of fig. 1, wherein the separation step b) of the effluent 3 obtained from the hydrotreatment step a) is able to additionally produce a fraction 22 comprising compounds having a boiling point between 180 and 350 ℃.

The above description of fig. 1 and 2 is an embodiment of the invention, which is not intended to limit the invention in any way. Only the main steps are shown in the figure, but it is understood that all equipment (drums, pumps, exchangers, furnaces, towers, etc.) required for the operation are present. Only the main stream containing hydrocarbons is shown, but it is understood that a hydrogen-rich gas stream (make-up or recycle) may be injected at the inlet of each catalytic reactor or bed or between two catalytic reactors or beds. Means for purifying and recycling hydrogen, well known to those skilled in the art, are also used. The hydrogen produced during the steam cracking step is advantageously used to supplement the hydrotreating step a) and/or the hydrocracking step d).

According to a variant not shown, at least a portion of the pyrolysis oil fraction 21 obtained from the separation step h) may be injected upstream of the deasphalting step c) and/or the hydrocracking step d). Advantageously, this variant enables elimination of asphaltenes contained in the pyrolysis oil and thus maximises the olefin yield.

According to a variant not shown, the pyrolysis oil fraction 21 obtained from the separation step h) can be separated into at least two fractions, for example into a light pyrolysis oil fraction, which is at least partially sent to the hydrocracking step d), and a heavy pyrolysis oil fraction, which is at least partially sent to the hydrotreating step a) and/or the deasphalting step c). Advantageously, this variant enables further maximization of the olefin yield.

The treated feedstock and the various steps of the process of the present invention are described in more detail below.

Raw materials

The heavy hydrocarbon feedstock 1 treated in the process of the invention is advantageously a hydrocarbon feedstock containing asphaltenes, and in particular having a C7 asphaltene content of at least 1.0 wt%, preferably at least 2.0 wt%, relative to the weight of the feedstock.

Feed 1 has an initial boiling point of at least 180 ℃, preferably at least 350 ℃, and more preferably at least 520 ℃ and a final boiling point of at least 600 ℃.

The hydrocarbon feedstock 1 according to the present invention may be selected from atmospheric residues, vacuum residues obtained from direct distillation, crude oil, topped crude oil, tar sands or derivatives thereof, bitumen schists or derivatives thereof, and source rock oils or derivatives thereof, alone or in combination. In the present invention, the feedstock to be treated is preferably an atmospheric residue or a vacuum residue, or a mixture of these residues, and more preferably a vacuum residue.

The heavy hydrocarbon feedstock treated in the process may contain, inter alia, sulfur impurities. The sulphur content may be at least 0.1 wt%, at least 0.5 wt%, preferably at least 1.0 wt%, more preferably at least 2.0 wt%, relative to the weight of the feedstock.

The heavy hydrocarbon feedstock treated in the process may contain, inter alia, metals. The nickel and vanadium content may be at least 10 ppm, preferably at least 30 ppm, relative to the weight of the feedstock.

The heavy hydrocarbon feedstock treated in the process may contain, inter alia, conradson carbon residue. The conradson carbon residue content may be at least 2.0 wt.%, preferably at least 5.0 wt.%, relative to the weight of the feedstock.

These starting materials can advantageously be used as such. Alternatively, the feedstock may be blended with at least one co-feed stock.

Preferably, a plurality of co-feeds may be used in the various steps of the process of the present invention to adjust the viscosity of the feed introduced at each step. The combined feed may be introduced upstream of the at least one reactor of the hydrotreatment step a). Such co-feed may be a mixture of hydrocarbon fractions or lighter hydrocarbon fractions, which may preferably be selected from the products obtained from fluid bed catalytic cracking (FCC or fluid catalytic cracking) processes, in particular light fractions (LCO or light cycle oil), heavy fractions (HCO or heavy cycle oil), decant oil, FCC residual oil. Such co-feed may also be an atmospheric or vacuum diesel fraction, obtained by atmospheric or vacuum distillation of crude oil or of effluents from conversion processes, such as coking or visbreaking, or obtained from separation steps c) and/or e). This combined feed constitutes no more than 20 wt% of the heavy hydrocarbon feed 1.

Hydrotreating step a)

According to the invention, the hydrotreating step a) is carried out in a fixed bed reactor, wherein the heavy hydrocarbon feedstock 1 or feedstock mixture is contacted with a hydrotreating catalyst in the presence of hydrogen. Advantageously, the feedstock or mixture of feedstocks is introduced into step a) in the presence of a combined feedstock.

The term "hydrotreatment", often referred to as HDT, refers to a catalytic treatment under hydrogen supply capable of refining a hydrocarbon feedstock, in other words, of significantly reducing the content of metals, sulphur and other impurities, while improving the hydrogen-to-carbon ratio in the feedstock and while converting the feedstock more or less partially into lighter fractions. Hydrotreating includes in particular hydrodesulfurization (often referred to as HDS) reactions, hydrodenitrogenation (often referred to as HDN) reactions and hydrodemetallization (often referred to as HDM) reactions, accompanied by hydrogenation, hydrodeoxygenation, hydrodearomatization, hydroisomerization, hydrodealkylation, hydrocracking or hydrodeasphalting reactions and by a reduction in conradson carbon residue.

According to one variant of the invention, the hydrotreatment step a) comprises a first Hydrodemetallization (HDM) step a1) carried out in one or more hydrodemetallization zones in a fixed bed and a subsequent second Hydrodesulfurization (HDS) step a2) carried out in one or more hydrodemetallization zones in a fixed bed. During the first hydrodemetallization step a1), the feedstock and hydrogen are contacted over a hydrodemetallization catalyst under hydrodemetallization conditions, and then during the second hydrodesulphurization step a2), the effluent from the first hydrodemetallization step a1) is contacted with a hydrodesulphurization catalyst under hydrodesulphurization conditions. This process, called HYVAHL-F^TMFor example, described in patent US 5417846.

According to another variant of the invention, when the raw material contains more than 70 ppm, or even more than 150 ppm, of metals and/or when the raw material contains impurities that easily cause blockages, such as iron derivatives, it is advantageous to use interchangeable protective reactors (PRS technology, i.e. permeable Reactor System) as described in patent FR 2681871. These interchangeable guard reactors are typically fixed beds located upstream of a fixed bed hydrodemetallization section.

The hydrotreatment step a) according to the invention is carried out under hydrotreatment conditions. It can advantageously be carried out at a temperature of between 300 and 450 ℃, preferably between 350 and 420 ℃ and at an absolute pressure of between 5 and 35 MPa, preferably between 11 and 20 MPa. The temperature is typically adjusted depending on the desired level of hydroprocessing and the desired duration of the treatment. Most commonly, the space velocity of the hydrocarbon feedstock, often referred to as HSV, which is defined as the volumetric flow rate of the feedstock divided by the total volume of the catalyst, can be in the range of 0.1 to 5.0 h^-1Preferably 0.1 to 2.0 h^-1And more preferably 0.1 to 1.0 h^-1Within the range of (1). Mixing with raw materialsThe amount of hydrogen may be in the range of 100 to 5000 standard cubic meters (Nm)³) Per cubic meter (m)³) Between liquid raw materials, preferably between 200 and 2000 Nm³/m³And more preferably between 300 and 1500 Nm³/m³In the meantime. The hydrotreating step a) can be carried out industrially in one or more fixed-bed reactors with a liquid descending stream.

The hydrotreating catalyst used is preferably a particulate catalyst comprising at least one metal or metal compound having a hydrodehydrogenating function on a support. These catalysts may advantageously be catalysts comprising at least one group VIII metal and/or at least one group VIB metal, preferably molybdenum and/or tungsten, generally selected from nickel and cobalt. It is possible to use, for example, a catalyst comprising from 0.5 to 10% by weight of nickel, preferably from 1 to 5% by weight of 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 MoO) on an inorganic support₃) The catalyst of (1). Such a support can be selected, for example, from the group consisting of alumina, silica-alumina, magnesia, clay and mixtures of at least two of these minerals. Advantageously, the support may contain other doping compounds, in particular oxides selected from the group consisting of boron oxide, zirconium oxide, cerium oxide, titanium oxide, phosphoric anhydride and mixtures of these oxides. Alumina supports are most commonly used, and very often alumina supports doped with phosphorus and optionally boron are used. When phosphoric anhydride P is present₂O₅When the concentration is less than 10% by weight. When boron trioxide B is present₂O₅When the concentration is less than 10% by weight. The alumina used may be gamma (gamma) or eta (eta) alumina. Such catalysts are most often in the form of extrudates. The total content of oxides of group VIB and VIII metals may be from 5 to 40 wt.%, and typically from 7 to 30 wt.%, and the weight ratio of group VIB to group VIII metals, calculated as metal oxides, is typically between 20 and 1, and most typically between 10 and 2.

In the case of a hydrotreating step comprising a Hydrodemetallization (HDM) step and then a Hydrodesulfurization (HDS) step, it is preferable to use a specific catalyst suitable for each step.

Catalysts which can be used in the hydrodemetallization step are indicated, for example, in patent documents EP 0113297, EP 0113284, US 5221656, US 5827421, US 7119045, US 5622616 and US 5089463. Preferably, the HDM catalyst is used in an interchangeable guard reactor.

Catalysts which can be used in the hydrodesulphurization step are indicated, for example, in patent documents EP 0113297, EP 0113284, US 6589908, US 4818743 or US 6332976.

It is also possible to use a mixed catalyst active in hydrodemetallization and hydrodesulfurization for both the hydrodemetallization and hydrodesulfurization sections, as described in patent document FR 2940143.

The catalyst used in the process of the invention is preferably subjected to an in situ (in situ) or ex situ (ex situ) sulphidation treatment prior to injection of the feedstock.

The effluent 3 obtained at the end of the hydrotreatment step a) comprises at least one heavy liquid fraction 5, also called residual liquid fraction, and gas-containing, in particular H₂、H₂S、NH₃And C₁-C₄A gaseous fraction 4 of hydrocarbons, in other words those containing 1 to 4 carbon atoms.

Separation step b)

According to the invention, the process comprises a step b) of separating the effluent 3 obtained from the hydrotreatment step a) into a gaseous fraction 4, a fraction 11 comprising compounds having a boiling point between 350 and 520 ℃ and at least one liquid residue fraction 5 comprising compounds having a boiling point of at least 520 ℃.

The separation of the gaseous fraction 4 from the effluent 3 can be carried out using separation devices known to those skilled in the art, in particular using one or more settlers (disengagers) which can be operated at different pressures and temperatures, optionally in combination with hydrogen or steam stripping devices and with one or more distillation columns. After optional cooling, this gas fraction 4 is preferably treated in a hydrogen purification unit to recover hydrogen not consumed during the hydrotreating reaction.

The purified hydrogen can then advantageously be recycled into the process of the invention. The hydrogen can be recycled at the inlet and/or various locations of the hydrotreating step a) and/or the fixed bed hydrocracking step d).

The separation step b) comprises a vacuum distillation wherein the effluent 3 obtained from step a) is fractionated by vacuum distillation into at least one vacuum distillate fraction 11 and at least one vacuum residue fraction 5. Vacuum distillate fraction 11 comprises vacuum gas oil fractions, these being compounds having a boiling point between 350 and 520 ℃. The heavy liquid fraction 5 is preferably a liquid hydrocarbon fraction containing at least 80% of compounds having a boiling point greater than or equal to 520 ℃.

The separation step b) preferably comprises first an atmospheric distillation, meaning upstream of the vacuum distillation, in which the liquid hydrocarbon fraction obtained after the separation is fractionated by atmospheric distillation into at least one atmospheric distillate fraction 22 and at least one atmospheric residue fraction, and then a vacuum distillation in which the atmospheric residue fraction obtained after the atmospheric distillation is fractionated by vacuum distillation into at least one vacuum distillate fraction 11 and at least one vacuum residue fraction 5.

Advantageously, the separation step b) further comprises at least one atmospheric distillation upstream of the vacuum distillation, in which the effluent 3 is fractionated by atmospheric distillation into at least one distillate fraction containing naphtha, in other words comprising compounds having a boiling point between 80 and 180 ℃, and a distillate fraction 22 containing diesel, in other words comprising compounds having a boiling point between 180 and 350 ℃.

Advantageously, the naphtha-containing distillate fraction is at least partially, preferably completely, sent to steam cracking step g). The diesel-containing distillate fraction 22 is at least partially, preferably completely, passed to the extraction step d). The diesel containing distillate fraction 22 may optionally be partly sent to hydrocracking step e).

The vacuum residue fraction 5 is at least partially, preferably completely, sent to the deasphalting step c).

The vacuum distillate fraction 11 is at least partially, preferably completely, sent to the fixed bed hydrocracking step d) and/or the aromatics extraction step f).

Deasphalting step c)

According to the invention, the process comprises a deasphalting step c) by liquid-liquid extraction obtained from the residual fraction 5 of the separation step b). Said step c) is carried out by liquid-liquid extraction using a solvent or a mixture of solvents 6, capable of producing on the one hand a fraction 7 containing bitumen and on the other hand a fraction 8 of deasphalted oil (DAO).

The deasphalting step c) is preferably carried out under specific conditions capable of producing DAO 8 of good quality, preferably DAO 8 with a low asphaltene content.

The deasphalting step c) is preferably carried out in a single step with the aid of a nonpolar solvent or a mixture of nonpolar solvents.

Step c) may be carried out in an extraction column or extractor, or in a mixer-settler. Step c) is preferably carried out in an extraction column comprising liquid-liquid contactors (packing elements and/or plates etc.) arranged in one or more zones. The solvent or solvent mixture 6 is preferably introduced into the extraction column at two different levels. The deasphalted feedstock is preferably introduced into the extraction column at only one introduction level, generally as a mixture with at least a portion of the solvent or solvent mixture 6, and generally below the first zone of the liquid-liquid contactor. Preferably, another portion of the solvent or solvent mixture 6 is injected below the deasphalted feedstock, typically below the second zone of the liquid-liquid contactor, and the deasphalted feedstock is injected above the second zone of the contactor.

Step c) is carried out under subcritical conditions of said solvent or solvent mixture 6, in other words below the critical point. Step c) is carried out at a temperature advantageously between 50 and 350 ℃, preferably between 80 and 320 ℃, more preferably between 120 and 310 ℃ and still more preferably between 150 and 300 ℃ and at a pressure advantageously between 0.1 and 6 MPa, preferably between 1 and 6 MPa, more preferably between 2 and 5 MPa.

The ratio of the volume of solvent or solvent mixture 6 to the mass of residue fraction 5 obtained from step b) is generally between 1/1 and 12/1, preferably between 2/1 and 9/1, expressed in litres per kilogram. This ratio includes the entire solvent or solvent mixture, which may be divided over several injection points.

The non-polar solvent used is preferably a solvent consisting of saturated hydrocarbons containing a carbon number greater than or equal to 3, preferably between 3 and 5. These solvents may be, for example, propane, butane or pentane. These solvents are used in pure form or as mixtures.

The solvent 6 used in step c) is preferably a non-polar solvent consisting to at least 80% by volume of saturated hydrocarbons containing a carbon number between 3 and 7, preferably between 4 and 5, in order to maximize the yield of the DAO fraction 8.

The choice of temperature and pressure conditions for the extraction, combined with the choice of the nature of the solvent 6 in the deasphalting step c), enables the extraction performance to be adjusted. With these specific deasphalting conditions, step c) makes it possible to precipitate from the bituminous fraction 7 a regulated amount of heavy resins and polar structures of the asphaltene type, thus enabling bituminous fraction 7 to be obtained in moderate yields, generally less than 40% or even less than 30% with respect to the amount of compounds having a boiling point higher than 520 ℃ entering the deasphalting step c). The high yield of DAO 8 enables the production of more cracked products at the outlet of the steam cracking step g). The resulting DAO fraction 8 contains less than 2000 ppm C7 asphaltenes, typically less than 1000 ppm C7 asphaltenes, or even less than 500 ppm C7 asphaltenes.

A fraction comprising DAO 8 and a portion of the solvent or solvent mixture is recovered at the top of the extraction column or mixer-settler, preferably above the uppermost liquid-liquid contactor region.

At the bottom of the extraction column or mixer-settler, preferably below the lowest located contactor zone, a fraction 7 comprising bitumen and some solvent or solvent mixture is recovered.

The solvent or solvent mixture 6 may consist of make-up (top-up) and/or a portion recycled during the separation step. These make-ups are advantageously able to compensate for the loss of solvent in the bitumen fraction 7 and/or the DAO fraction 8 caused by the separation step.

The deasphalting step c) comprises an integrated sub-step of separating a fraction 8 comprising DAO and a solvent or a mixture of solvents. The recovered solvent or solvent mixture may be recycled in the deasphalting step c). Such integrated separation sub-step, which makes it possible to separate DAO 8 and the solvent or solvent mixture, can use all the necessary equipment known to the person skilled in the art (settling drums, distillation or stripping columns, heat exchangers, furnaces, pumps, compressors, etc.).

At least a portion, preferably all, of the DAO 8 is sent to the aromatic extraction step d).

Aromatic extraction step d)

According to the invention, the process comprises a step d) of extracting aromatic hydrocarbons from at least a portion of the deasphalted oil fraction 8 obtained from the deasphalting step c). This step can yield an extract fraction 13 and a raffinate fraction 10.

Advantageously, a portion of the distillate fraction 22 obtained from separation step b) comprising compounds having a boiling point between 180 and 350 ℃ is also introduced into the aromatic extraction step d).

Optionally, a portion of the fraction obtained from separation step b) and comprising compounds having a boiling point between 350 and 520 ℃ may be introduced into extraction step d).

The purpose of the aromatic extraction step is to extract at least partially the aromatic compounds, as well as the resins contained in the DAO fraction, by liquid-liquid extraction with the aid of a polar solvent 9.

The extraction of aromatics is preferably performed on fractions having boiling points above 180 ℃ and preferably above 350 ℃ to prevent yield loss of light fractions during solvent recovery after extraction.

The boiling point of the extracted compounds during step d) is preferably higher than the boiling point of the solvent, thereby advantageously enabling to maximize the yield in the separation of the solvent from the raffinate after extraction. In addition, solvent recovery is more efficient and economical.

The solvent used may be furfural, N-methyl-2-pyrrolidone (NMP), sulfolane, Dimethylformamide (DMF), dimethyl sulfoxide (DMSO), phenol or mixtures of these solvents in equal or different proportions. The solvent is preferably furfural.

The operating conditions are, in general, a ratio of solvent/starting material of step d) of from 1/2 to 3/1, preferably from 1/1 to 2/1, a temperature profile between ambient temperature and 150 ℃, preferably between 50 and 150 ℃. The pressure lies between atmospheric pressure and 2.0 MPa, preferably between 0.1 and 1.0 MPa.

Liquid-liquid extraction can be carried out generally in a mixer-settler or in an extraction column operated in countercurrent mode. The extraction is preferably carried out in an extraction column.

The solvent selected has a sufficiently high boiling point to fluidize the feedstock of step d) without evaporating.

After having brought the solvent into contact with the effluent introduced in step d), two fractions are obtained at the end of step d): extract fraction 13, consisting of the portion of the heavy fraction that is insoluble in the solvent (and highly concentrated in aromatics), and raffinate fraction 10, consisting of the solvent and the soluble portion of the heavy fraction. The solvent is separated from the soluble fraction by distillation and internally recycled to the liquid-liquid extraction process. The separation of the extract from the raffinate and the recovery of the solvent are carried out in a separation substep integrated into the aromatic extraction step d).

Fixed bed hydrocracking step e)

According to the invention, the process comprises a fixed bed hydrocracking step e) of at least a portion of the fraction 11 obtained from the separation step b) and of at least a portion of the extract fraction 13 obtained from the extraction step d) in the presence of a hydrocracking catalyst.

The hydrogen 12 can also be injected upstream of the various catalytic beds constituting the hydrocracking reactor. In parallel with the hydrocracking reactions required in this step, any type of hydrotreating reaction (HDM, HDS, HDN, etc.) also takes place. Hydrocracking reactions occur that result in the formation of atmospheric distillates, with the degree of conversion of vacuum distillates to atmospheric distillates typically being greater than 30%, typically between 30% and 50% for mild hydrocracking, and greater than 80% for higher hydrocracking. The use of specific conditions, in particular temperature conditions and/or one or more specific catalysts, makes it possible to promote the desired hydrocracking reactions.

The hydrocracking step e) according to the invention is carried out under hydrocracking conditions. It can advantageously be carried out at a temperature of between 340 and 480 ℃, preferably between 350 and 430 ℃ and at an absolute pressure of between 5 and 25 MPa, preferably between 8 and 20 MPa, more preferably between 10 and 18 MPa. The temperature is typically adjusted depending on the desired level of hydroprocessing and the desired duration of the treatment. Most commonly, the space velocity of a hydrocarbon feedstock, often referred to as HSV, is defined as the volumetric flow rate of the feedstock divided by the catalystThe total volume can be 0.1-3.0 h^-1Preferably 0.2 to 2.0 h^-1And more preferably 0.25 to 1.0 h^-1Within the range of (1). The amount of hydrogen mixed with the feedstock may range from 100 to 5000 standard cubic meters (Nm)³) Per cubic meter (m)³) Between liquid raw materials, preferably between 200 and 2000 Nm³/m³And more preferably between 300 and 1500 Nm³/m³In the meantime. The hydrocracking step e) can be carried out industrially in at least one reactor having a liquid descending stream.

The hydrocracking step e) preferably comprises two catalytic stages in series, with an upstream hydrotreating catalytic stage to limit deactivation of the downstream hydrocracking catalytic stage. Such a hydrotreatment stage is particularly intended to significantly reduce the nitrogen content of the feedstock, nitrogen being an inhibitor of the acid functionality of the bifunctional catalyst of the hydrocracking catalytic stage. The hydrocracking step e) may also comprise a second hydrocracking catalytic section for treating at least one heavy fraction (cut) coming from the separation step.

The catalyst used in hydrocracking step e) may be a hydrotreating and hydrocracking catalyst.

The hydrotreating catalyst used may be a hydrotreating catalyst consisting of a support of the inorganic oxide type, preferably alumina, and an active phase containing chemical elements of group VIII (Ni, Co, etc.) and group VI (Mo, etc.) of the periodic table.

The hydrocracking catalyst may advantageously be a bifunctional catalyst having a hydrogenation phase to enable the hydrogenation of aromatics and the production of an equilibrium between saturated compounds and the corresponding olefins, and an acid phase capable of promoting the hydroisomerization and hydrocracking reactions. The acid function is advantageously composed of a high surface area (typically 100 to 800 m) exhibiting surface acidity².g^-1) Supports such as halogenated (especially chlorinated or fluorinated) alumina, combinations of boron and aluminum oxides, amorphous silica-alumina and zeolites are provided. The hydrogenating function is advantageously formed from one or more metals from group VIII of the periodic Table of the elements, such as iron, cobalt, nickel, ruthenium, rhodium, palladium, osmium, iridium and platinum, or from at least one metal from group VIB of the periodic Table, such as molybdenum and tungsten, and at least one non-noble metal from group VIII, such as nickel and cobaltAre provided. Preferably, the bifunctional catalyst used comprises at least one metal selected from the group consisting of group VIII and VIB metals, used alone or in mixture, and a support comprising from 10 to 90% by weight of zeolite and from 90 to 10% by weight of inorganic oxide. The group VIB metal used is preferably selected from tungsten and molybdenum, and the group VIII metal is preferably selected from nickel and cobalt. According to another preferred variant, the monofunctional and bifunctional catalysts of the alumina, amorphous silica-alumina or zeolite type can be used as a mixture or in successive layers.

Preferably, the volume of catalyst used during the second hydrocracking step e) consists of at least 30% of the hydrocracking catalyst of the bifunctional type.

Optionally, a co-feed (not shown) may be injected upstream of any catalytic bed of the hydrocracking section d). Such co-feeds are typically vacuum distillates, obtained from direct distillation or from conversion processes, or deasphalted oils.

The hydrocracking step e) is preferably operated in "maximum naphtha (maxi naphtha)" mode, meaning that the yield of liquid compounds having a boiling point of less than 220 ℃ is greater than 50% by weight of the feedstock entering the hydrocracking step e).

The effluent 14 obtained from the fixed bed hydrocracking step e) is sent to the separation step f).

Separation step f) of the effluent of fixed bed hydrocracking

According to the invention, the process further comprises a step f) of separating the effluent 14 obtained from the fixed bed hydrocracking step e) into at least one gaseous fraction 15 and at least one liquid fraction 16.

Said effluent 14 is advantageously separated in at least one settling drum into at least one gaseous fraction 15 and at least one liquid fraction 16. The step of separating said effluent 14 can be carried out by means of any separation device known to the skilled person, such as one or more settling drums which can be operated at different pressures and temperatures, optionally in combination with a hydrogen or steam stripping device and with one or more distillation columns. These separators may for example be High Pressure High Temperature (HPHT) separators and/or High Pressure Low Temperature (HPLT) separators.

The gas fraction 15 obtained at the end of the separation step e) contains gases, such as H₂、H₂S、NH₃And C1-C4 hydrocarbons (e.g., methane, ethane, propane, and butane). The hydrogen contained in the gas fraction 15 is advantageously purified and recycled to any fixed bed hydrocracking and/or hydrotreating step. In a particular embodiment, the hydrogen contained in the gas fraction 15 can be purified while treating the separated gas fractions obtained from the effluents of the hydrotreating step a) and the hydrocracking step e). Hydrogen can be purified by amine washing, by membranes, by PSA (pressure swing adsorption) systems, or by two or more of these means arranged in series.

In a preferred embodiment, the separation step f), in addition to the gas-liquid separation or continuous separation device, also comprises at least one atmospheric distillation, wherein the liquid hydrocarbon fraction obtained after the separation is fractionated by atmospheric distillation into at least one atmospheric distillate fraction 16 comprising compounds having a boiling point of less than 350 ℃, and optionally a liquid fraction comprising vacuum distillate comprising compounds having a boiling point of more than 350 ℃. At least a portion, preferably all, of the atmospheric distillate fraction 16 and optionally the fraction comprising vacuum distillate is advantageously sent to steam cracking step g).

Optionally, at least a portion of the vacuum distillate fraction is recycled to hydrocracking step e), and according to this variant, it may be necessary to perform a purge (purge) of the unconverted vacuum distillate fraction to reduce the concentration of polycyclic aromatic species and limit the deactivation of the hydrocracking catalyst of step e). In order to limit this purge (purge) and increase the overall conversion, it may be advantageous to optionally perform this purge (purge) by sending at least a portion of the unconverted vacuum distillate fraction to the inlet of the deasphalting step c) to at least partially remove the polycyclic aromatic hydrocarbon species in the asphaltic fraction 7.

Steam cracking step g)

According to the invention, the process comprises a raffinate fraction 10 obtained from the extraction step d) and a liquid fraction 16 obtained from the separation step f) comprising compounds having a boiling point of less than 350 ℃ and preferably a fraction comprising compounds having a boiling point of more than 350 ℃ obtained from the separation step f).

A portion of the fraction comprising compounds having a boiling point between 80 and 180 ℃ obtained from separation step b) may optionally be introduced into steam cracking step g).

The steam cracking step g) is advantageously carried out in at least one pyrolysis furnace at a temperature between 700 and 900 ℃, preferably between 750 and 850 ℃, at a relative pressure between 0.05 and 0.3 MPa. The residence time of the hydrocarbons is generally less than or equal to 1.0 second (abbreviated to s), preferably between 0.1 and 0.5 s. Steam is advantageously introduced upstream of steam cracking step g). The amount of water introduced is between 0.3 and 3.0 kg of water per kg of hydrocarbon entering step g). Step g) is preferably carried out in a plurality of pyrolysis furnaces connected in parallel, to adapt the operating conditions to the various streams supplied to step g) and obtained from steps b), e), f) and h), and also to manage the tube decoking time. The furnace comprises one or more tubes arranged in parallel. A furnace may also refer to a group of furnaces operating in parallel. Accordingly, one furnace may be dedicated to the cracking of an ethane-rich fraction, another for a propane-and butane-rich fraction, another for a fraction containing compounds having a boiling point between 80 and 180 ℃, another for a fraction containing compounds having a boiling point between 180 and 350 ℃, and another for a fraction of compounds having a boiling point greater than 350 ℃.

Separation of the steam cracking effluent h)

The process preferably comprises a step h) of separating the effluent 17 obtained from the steam cracking step g), capable of producing at least one fraction 18 comprising hydrogen, preferably consisting of hydrogen, a fraction 19 comprising ethylene, preferably consisting of ethylene, a fraction 20 comprising propylene, preferably consisting of propylene, and a fraction 21 comprising pyrolysis oil, preferably consisting of pyrolysis oil. Optionally, the separation step h) also enables the recovery of a fraction comprising, preferably consisting of, butenes and a fraction comprising, preferably consisting of, pyrolysis gasoline.

The fraction enriched in saturated compounds obtained from the light gases or pyrolysis gasolines from the separation step h) can preferably be recycled to the steam cracking step g), in particular ethane and propane, in order to increase the yields of ethylene and propylene.

The pyrolysis oil fraction 21 may optionally be subjected to additional separation steps to produce a number of fractions, for example a light pyrolysis oil comprising compounds having a boiling point of less than 350 ℃ and a heavy pyrolysis oil comprising compounds having a boiling point of greater than 350 ℃. The light pyrolysis oil may advantageously be injected upstream of the hydrocracking step d). The heavy pyrolysis oil may advantageously be injected upstream of the hydrotreating step a) and/or the deasphalting step c). Advantageously, the separation of fraction 21 into two fractions and the recycling of these fractions to one of steps a), c) or e) of the process enables the maximum formation of olefins from the heavy hydrocarbon feedstock.

Examples

The following examples illustrate specific implementations of the method of the present invention, but do not limit its scope.

The heavy hydrocarbon feedstock 1 treated in this process is an atmospheric residuum originating from the middle east and having the properties shown in table 1.

[ Table 1]

Sulfur content	% m/m	4.08
			Mass per unit volume	kg/m³	979
C7 asphaltene content	% m/m	4.2
			Ni + V content	ppm	81
Content of compounds having a boiling point of greater than 520 DEG C	% m/m	55

TABLE 1 raw material properties.

[ Table 2]

Temperature of	℃	370
			Partial pressure of hydrogen	MPa abs	16
H₂/HC (hydrogen cover volume/feedstock volume)	Nm³/m³	1000
			HSV hydrogenation demetalization catalyst	h^-1	0.7
HSV hydrodesulfurization catalyst	h^-1	0.5

TABLE 2 conditions of the hydrotreatment step a).

The feedstock was subjected to a fixed bed hydrotreating step a) under the conditions shown in table 2. The effluent 3 obtained from the hydrotreatment step is subjected to a separation step b) comprising a separation drum and an atmospheric distillation column and a vacuum distillation column. The yields of the various fractions obtained after the separation are shown in table 3 (mass% relative to the feedstock upstream of the hydrotreatment step, abbreviated to% m/m):

[ Table 3]

NH3+H2S	% m/m	4.0
			Fraction 4 (C1-C4)	% m/m	0.6
Fraction 22 (PI-350 ℃ C.)	% m/m	12.0
			Fraction 11 (350-520 ℃ C.)	% m/m	42.1
Fraction 5 (520 ℃ C. +)	% m/m	42.6

TABLE 3 yield after separation in step b) of the hydrotreatment step a).

Fraction 5 (520 ℃ +) of the vacuum residue type is sent to a deasphalting step c), carried out in an extraction column operating continuously, with the conditions listed in table 4:

[ Table 4]

Nature of the solvent	-	n-pentane
			Volume of solvent/volume of deasphalted feedstock	v/v	8/1
Temperature at the top of the extractor	℃	180
			Temperature at the bottom of the extractor	℃	130
Pressure at the top of the extractor	MPa abs	3.7

TABLE 4 conditions of the deasphalting step c).

At the end of the deasphalting step c), a DAO fraction 8 was obtained in a yield of 91.5% and a pitch fraction (pitch fraction) was obtained in a yield of 8.5%; these yields, based on the feedstock of the deasphalting step, correspond to fraction 5 (520 ℃ C. +) of the separation step b) of the effluent obtained from the hydrotreatment step a).

The DAO fraction 8 obtained from the deasphalting step c) and the fraction 22 obtained from the separation step b) (PI-350 ℃) are sent to an aromatic extraction step d), which is carried out in a mixer-settler, with the conditions listed in table 5:

[ Table 5]

Nature of the solvent	-	Furfural
			Volume of solvent/volume of extraction feedstock	v/v	1.5/1.0
Temperature of extraction	℃	110
			Pressure of extraction	MPa abs	0.5

TABLE 5 conditions for the extraction step d).

At the end of the aromatic extraction step, a dearomatized raffinate fraction 10 was obtained in 44.4% yield and an aromatic-rich extract fraction 13 was obtained in 55.6% yield; these yields are based on the total feed introduced into the aromatic extraction step d) (fraction 8 + fraction 22).

Fraction 11 of the vacuum distillate type (350-:

[ Table 6]

Temperature of hydrotreatment	℃	377
			Hydrocracking temperature	℃	375
Partial pressure of hydrogen	MPa abs	16
			H₂/HC (hydrogen cover volume/feedstock volume)	Nm³/m³	1000
HSV hydrotreating catalyst	h^-1	0.85
			HSV hydrocracking catalyst	h^-1	0.90

TABLE 6 conditions for the hydrocracking step e).

The effluent 14 obtained from the hydrocracking step is subjected to a separation step f) comprising a separation drum and an atmospheric distillation column. The yields of the various fractions obtained after the separation are shown in table 7 (mass% relative to the feedstock upstream of the hydrotreatment step, abbreviated to% m/m):

[ Table 7]

NH₃+H₂S	% m/m	0.6
			C1-C4	% m/m	4.9
PI-220℃	% m/m	65.5
			220-350℃	% m/m	22.4
350℃	% m/m	8.7

TABLE 7 yield of hydrocracking step e) after isolation in step f).

The liquid fractions PI-220 ℃, 220-350 ℃ and 350 ℃ of the separation step of the effluent from the hydrocracking step and the raffinate fraction 10 from the aromatics extraction step d) were sent to the steam cracking step g), wherein each liquid fraction was cracked under various conditions (Table 8).

[ Table 8]

Pressure at furnace outlet	MPa abs	0.2
			Furnace exit temperature, fraction PI-220 deg.C	℃	800
Temperature at furnace exit, fraction 220-	℃	790
			Temperature at furnace exit, fraction 350 ℃ + and raffinate	℃	780
Steam/fraction PI-220 ℃ ratio	kg/kg	0.6
			Steam/fraction 220 ℃ ratio of 350 ℃	kg/kg	0.8
Steam/fraction (350 ℃ + and raffinate) ratio	kg/kg	1.0
			Furnace residence time, fraction PI-220 deg.C	s	0.3
Furnace residence time, fraction 220-	s	0.3
			Furnace residence time, fraction 350 ℃ + and raffinate	s	0.3

TABLE 8 conditions for steam cracking step g).

The effluents from the various steam cracking furnaces are subjected to a separation step h) which enables recycling of the saturated compounds and yields (mass% relative to the total feedstock upstream of the steam cracking step) shown in table 9.

[ Table 9]

H2、CO、C1	% m/m	8.2
			Ethylene	% m/m	35.5
Propylene (PA)	% m/m	19.3
			C4 fraction	% m/m	15.4
Pyrolysis gasoline	% m/m	18.2
			Pyrolysis oil	% m/m	3.3

TABLE 9 yields after steam cracking step g) isolation in step h).

Table 9 shows the yields of steam cracked products. The process of the invention enables yields by mass of ethylene and propylene of 31.8% and 17.3%, respectively, with respect to the atmospheric residue feed introduced into the hydrotreatment step a). Furthermore, the particular sequence of steps upstream of the steam cracking step can limit coking.

Claims

1. A process for the production of olefins from a hydrocarbon feedstock (1) having a sulphur content of at least 0.1 wt%, an initial boiling point of at least 180 ℃ and a final boiling point of at least 600 ℃, the process comprising the steps of:

a) a hydroprocessing step carried out in a fixed bed reactor, wherein said heavy hydrocarbon feedstock (1) is contacted with a hydroprocessing catalyst in the presence of hydrogen, said step producing an effluent (3),

b) a step of separating the effluent (3) obtained from the hydrotreatment step a) into a gaseous fraction (4), a fraction (11) comprising compounds having a boiling point between 350 and 520 ℃ and a liquid vacuum residue fraction (5) comprising compounds having a boiling point of at least 520 ℃,

c) a step of deasphalting by liquid-liquid extraction the fraction of the vacuum residue (5) obtained from the separation step b), said step c) being carried out with the aid of a solvent (6) or a mixture of solvents, capable of producing, on the one hand, a fraction (7) containing bitumen and, on the other hand, a fraction of deasphalted oil (8),

d) a step of extracting aromatic hydrocarbons from at least a portion of the deasphalted oil fraction (8) obtained from the deasphalting step c), capable of producing an extract fraction (13) and a raffinate fraction (10),

e) a step of subjecting at least a portion of the fraction (11) obtained from the separation step b) and at least a portion of the extract fraction (13) obtained from the extraction step d) to fixed bed hydrocracking in the presence of a hydrocracking catalyst capable of producing an effluent (14),

f) a step of separating the effluent (14) obtained from the fixed bed hydrocracking step e) into at least one gaseous fraction (15) and at least one liquid fraction (16),

g) a step of steam cracking the raffinate fraction (10) obtained from the extraction step d) and the liquid fraction (16) obtained from the separation step f) comprising compounds having a minimum boiling point of less than 350 ℃, capable of producing an effluent (17),

h) a step of separating the effluent (17) obtained from the steam cracking step g) capable of producing at least one fraction (18) containing hydrogen, a fraction (19) containing ethylene, a fraction (20) containing propylene and a fraction (21) containing pyrolysis oil.

2. The process according to claim 1, wherein the separation step b) comprises vacuum distillation capable of producing at least one vacuum distillate fraction (11) and at least one vacuum residue fraction (5).

3. The process according to claim 2, wherein the separation step b) comprises, upstream of the vacuum distillation, an atmospheric distillation capable of producing at least one atmospheric distillate fraction (22) and at least one atmospheric residue fraction, said atmospheric residue fraction being fed to said vacuum distillation capable of producing at least one vacuum distillate fraction (11) and at least one vacuum residue fraction (5).

4. The process according to any of the preceding claims, wherein the residue fraction (5) obtained from step b) is sent in its entirety to the deasphalting step c).

5. The process according to any one of the preceding claims, wherein the solvent (6) used in step c) is a non-polar solvent consisting to an extent of at least 80% by volume of saturated hydrocarbons comprising a carbon number between 3 and 7.

6. A process according to claim 3, wherein a portion of the distillate fraction (22) obtained from separation step b) is introduced into the aromatic extraction step d).

7. The process according to any of the preceding claims, wherein the fraction boiling above 180 ℃ is subjected to an aromatic extraction step d).

8. The process according to any of the preceding claims, wherein the boiling point of the extracted compounds during step d) is higher than the boiling point of the solvent (6) used.

9. The process according to any one of the preceding claims, wherein the hydrocracking step e) is operated such that the yield of liquid compounds having a boiling point of less than 220 ℃ is more than 50 wt% of the feedstock entering the hydrocracking step e).

10. The process according to any one of the preceding claims, wherein the separation step f) comprises at least one atmospheric distillation capable of producing at least one atmospheric distillate fraction (16) comprising compounds having a boiling point of less than 350 ℃, and a liquid fraction comprising a vacuum distillate comprising compounds having a boiling point of more than 350 ℃.

11. The process according to claim 10, wherein the atmospheric distillate fraction (16) and the fraction comprising vacuum distillate are sent to steam cracking step g).

12. The process according to any one of the preceding claims, wherein a portion of the fraction comprising compounds having a boiling point between 80 and 180 ℃ obtained from separation step b) is introduced into steam cracking step g).

13. The process according to any one of the preceding claims, wherein the steam cracking step g) is carried out in at least one pyrolysis furnace at a temperature between 700 and 900 ℃, at a pressure between 0.05 and 0.3 MPa, for a residence time of less than or equal to 1.0 second.

14. The process according to any one of the preceding claims, wherein the fraction enriched in saturated compounds obtained from the light gas or pyrolysis gasoline from separation step h) can be recycled to steam cracking step g).

15. The process according to any one of the preceding claims, wherein the pyrolysis oil fraction (21) is subjected to an additional separation step to obtain a light pyrolysis oil comprising compounds having a boiling point of less than 350 ℃ and a heavy pyrolysis oil comprising compounds having a boiling point of more than 350 ℃, the light pyrolysis oil being injected upstream of the hydrocracking step e) and the heavy pyrolysis oil being injected upstream of the hydrotreating step a) and/or the deasphalting step c).