EP3999613A1

EP3999613A1 - Process for the preparation of olefins, comprising hydrotreatment, de-asphalting, hydrocracking and steam cracking

Info

Publication number: EP3999613A1
Application number: EP20735615.5A
Authority: EP
Inventors: Wilfried Weiss; Isabelle MERDRIGNAC
Original assignee: IFP Energies Nouvelles IFPEN
Current assignee: IFP Energies Nouvelles IFPEN
Priority date: 2019-07-17
Filing date: 2020-07-06
Publication date: 2022-05-25
Also published as: WO2021008924A1; CN114072483A; FR3098824A1; FR3098824B1; TW202113048A; CN114072483B; US20220380690A1

Abstract

The present invention relates to a process for the preparation of olefins from a hydrocarbon feedstock (1) having a sulphur content of at least 0.1 wt.%, an initial boiling temperature of at least 180 °C and a final boiling temperature of at least 600 °C.

Description

DOLEFINES PRODUCTION PROCESS INCLUDING HYDRO-TREATMENT, DESASPHALTING, HYDRO-CRACKING AND VAPOCRAQUAGE

TECHNICAL AREA

The present invention relates to a process for the production of olefins from heavy fractions of hydrocarbons containing, inter alia, sulfur impurities, metals and asphaltenes.

PRIOR TECHNIQUE

The improvement of engines and the gradual electrification of some of the vehicles have led to a change in demand for petroleum products with a tendency to reduce the growth in demand for fuels. Conversely, the growth in demand for petrochemical bases and in particular for olefins is more sustained. For example, ethylene and propylene are highly desirable olefins, because they are essential intermediates for many petrochemicals such as polyethylene and polypropylene. There is therefore an interest in further integrating the refining sites and the existing petrochemical sites, in remodeling the refining sites, so as to produce at least part of petrochemical bases, or to design new integrated refining-petrochemical schemes, or even to design sites where most or all of the crude is converted into petrochemical bases.

The main process for converting heavy hydrocarbon fractions into high yield olefins is steam cracking. The production of the desired olefins is accompanied by co-products, in particular aromatic compounds and pyrolysis oil which require purification steps. In addition, the selectivity for the desired olefins is highly dependent on the quality of the feeds introduced in the steam cracking step. There is therefore an interest in identifying new processes allowing the production of olefins from heavy hydrocarbon fractions in a more efficient, profitable manner and independent of the heavy hydrocarbon fraction treated.

Advantageously, the process according to the invention makes it possible to optimize the properties of the fractions which will be introduced in the steam cracking stage and thus to maximize the yields of olefins of interest during the steam cracking stage. In the processes for treating heavy fractions of hydrocarbons, the hydrotreatment of the residue in a fixed bed makes it possible to remove some of the contaminants from the feed, in particular metals, sulfur and asphaltenes.

It is also known to carry out deasphalting operations. Deasphalting separates an asphalt fraction rich in asphaltenes called pitch according to English terminology from a deasphalted oil fraction, called DAO for “DeAsphalted OU” according to English terminology, with a greatly reduced asphaltene content, thus facilitating its upgrading by catalytic cracking or hydrocracking.

The conversion products and more particularly the heavy cuts resulting from the conversion processes such as deasphalted oils and vacuum distillates are difficult to treat directly in a steam cracking step. The presence of high contents of naphthenic and aromatic compounds leads to a sharp drop in the yields of olefins of interest, to an increase in the yield of pyrolysis oil and to increased coking of the tubes of the steam cracking furnaces, which affects the operability. . It is therefore necessary to improve the operability of the steam cracking step in order to produce olefins with good yield.

The present invention aims to overcome the problems set out above, and in particular to provide a process allowing flexible and optimized production of olefins from heavy hydrocarbon feedstocks so as to improve the profitability of the olefin production process.

Thus, the Applicant has developed a new process for the production of olefins comprising a step of hydroconversion of residues in an ebullated bed, a step of deasphalting to produce a DAO fraction and an asphalt fraction, a step of hydrocracking in a fixed bed. , an extraction step to produce a raffinate and a fraction rich in aromatics and a steam cracking step of said raffinate.

The method according to the present invention has the following advantages:

- upgrading of heavy fraction into essential petrochemical intermediates,

- a production of olefins from heavy fractions with a good yield,

- reduction in the cost of olefin production, - flexibility of the process making it possible to treat all heavy hydrocarbon fractions regardless of their origins,

- the sequence of a residue hydroconversion step and a deasphalting step allowing a deep conversion of the residual fraction and in particular asphaltenes, - limitation of the formation of coke during said steam cracking step.

SUMMARY OF THE INVENTION

The object of the present invention relates to a process for the production of olefins from a hydrocarbon feed 1 having a sulfur content of at least 0.1% by weight, an initial boiling temperature of at least 180 ° C and a final boiling temperature of at least 600 ° C, said process comprising the following steps: a) a hydroconversion step carried out in an ebullating bed reactor in which said heavy hydrocarbon feed 1 in the presence of hydrogen 2 are brought into contact in the presence of a hydroconversion catalyst, said step making it possible to obtain an effluent 3; b) a step of separating the effluent 3 from hydroconversion step a) into a gaseous fraction 4, a fraction 1 1 comprising compounds having a boiling point of between 350 and 540 ° C and a fraction vacuum residue liquid 5 comprising compounds having a boiling point of at least 540 ° C, c) a deasphalting step by liquid-liquid extraction of the vacuum residue fraction 5 from separation step b), said step c) being carried out using a solvent 6 or a mixture of solvents making it possible to obtain, on the one hand, a fraction 7 comprising asphalt, and on the other hand a deasphalted oil fraction 8, d) a step of extracting the aromatics from at least part of the deasphalted oil fraction 8 from deasphalting step c) and from at least part of the fraction 11 from step b) from separation, making it possible to obtain an extract fraction 13 and a raffinate fraction 10, e) a hydrocracking stage e) in bed fixes at least part of the extracted fraction 13 resulting from the extraction step d) in the presence of hydrogen 12 and a hydrocracking catalyst, making it possible to obtain an effluent 14, f) a step of separating the effluent 14 from step e) of hydrocracking in a fixed bed into at least one gaseous fraction 15 and at least one liquid fraction 16, g) a step g) of steam cracking of the fraction raffinate 10 from step d) of extraction and from the liquid fraction 16 from step f) of separation comprising compounds having a boiling point of less than or equal to 350 ° C, making it possible to obtain an effluent 17, h) a step of separating the effluent 17 from steam cracking step g) making it possible to obtain at least one fraction 18 comprising hydrogen, from a fraction 19 comprising ethylene, a fraction 20 comprising propylene and a fraction 21 comprising pyrolysis oil.

In a preferred embodiment, step b) of separation comprises a vacuum distillation allowing the production of at least one vacuum distillate fraction 1 1 and at least one vacuum residue fraction 5.

In a preferred embodiment, step b) of separation comprises, upstream of the vacuum distillation, atmospheric distillation making it possible to obtain at least one atmospheric distillate fraction and at least one atmospheric residue fraction, said fraction atmospheric residue being sent to said vacuum distillation, making it possible to obtain at least one vacuum distillate fraction 1 1 and at least one vacuum residue fraction 5. In a preferred embodiment, all of the residue fraction 5 obtained from step b) is sent to step c) for deasphalting.

In a preferred embodiment, the solvent 6 used in step c) is an apolar solvent composed of at least 80% by volume of saturated hydrocarbon (s) comprising a carbon number of between 3 and 7 In a preferred embodiment, at least part of a distillate fraction resulting from stage b) of separation, is introduced into stage d) of extraction of the aromatics.

In a preferred embodiment, step d) for extracting the aromatics is carried out on fractions having a boiling point greater than or equal to 180 ° C. In a preferred embodiment, the compounds extracted during step d) have a boiling point higher than the boiling point of the solvent 6 used.

In a preferred embodiment, hydrocracking step e) is carried out so as to obtain a yield of liquid compounds having a boiling point of less than 220 ° C. greater than 50% by weight of the feed at the inlet of the hydrocracking step e).

In a preferred embodiment, the separation step f) comprises at least one atmospheric distillation making it possible to obtain at least one atmospheric distillate fraction 16 comprising compounds having a boiling point of less than 350 ° C. and a fraction liquid comprising vacuum distillate comprising compounds having a boiling point greater than 350 ° C.

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

In a preferred embodiment, part of a fraction comprising compounds having a boiling point between 80 and 180 ° C resulting from step b) of separation is introduced in step g) of steam cracking.

In a preferred embodiment, step g) of steam cracking is carried out in at least one pyrolysis furnace at a temperature between 700 and 900 ° C, under a pressure between 0.05 and 0.3 MPa for a period of time. stay less than or equal to 1.0 seconds.

In a preferred embodiment, the cuts rich in saturated compounds obtained from the light gases or from the pyrolysis gasoline obtained from stage h) of separation can be recycled to stage g) of steam cracking.

In a preferred embodiment, the pyrolysis oil fraction 21 is subjected to an additional separation step so as to obtain a light pyrolysis oil comprising compounds having a boiling point of less than 350 ° C and a heavy pyrolysis oil. comprising compounds having a boiling point greater than 350 ° C. Said light pyrolysis oil is injected upstream of hydrocracking step e), and said heavy pyrolysis oil is injected upstream of hydroconversion step a) and / or deasphalting step c). LIST OF FIGURES

FIG. 1 represents a sequence of the method according to the invention.

DESCRIPTION OF THE EMBODIMENTS

It is specified that, throughout this description, the expression "between ... and ...", "less than ..." or "greater than" must be understood as including the cited terminals.

In the sense of the present invention, the various embodiments presented can be used alone or in combination with each other, without limitation of combination.

In the remainder of the description, reference is made to FIG. 1, which illustrates an exemplary implementation of the process for producing olefins from heavy hydrocarbon feedstocks according to the invention. The mention of the elements referenced in Figure 1 in the remainder of the description allows a better understanding of the invention, without it being limited to the particular example illustrated in Figure 1.

As represented in FIG. 1, the method according to the invention comprises the following steps:

- a step a) of hydroconversion of the heavy hydrocarbon feed 1, in the presence of a gas rich in hydrogen 2 in at least one ebullating bed reactor comprising a hydroconversion catalyst;

- A step b) of separation of the effluent 3 from step a) of hydroconversion making it possible to obtain at least one fraction 4 comprising hydrogen, a liquid fraction 1 1 containing compounds having a temperature of boiling between 350 and 540 ° C and a heavy liquid fraction containing compounds having a boiling point above 540 ° C;

- a step c) of deasphalting fraction 5 from step b) of separation as a mixture with a solvent or a combination of solvents 6, making it possible to obtain at least one fraction comprising deasphalted oil (DAO) 8 , and a fraction 7 comprising asphalt;

- a step d) of extracting at least part of fraction 8 comprising deasphalted oil (DAO) from step c) of deasphalting and at least part of fraction 11 from step b) separation with a solvent or a combination of solvents 9, makes it possible to obtain at least a fraction 10 rich in saturated compounds (raffinate), and a fraction 13 rich in aromatic compounds (extract);

a hydrocracking step e) in the presence of a hydrogen-rich gas 12 and at least part of the fraction 13 rich in aromatics from the extraction step d), carried out in at least one reactor in fixed bed comprising a hydrocracking catalyst;

a step f) of separating the effluent 14 from hydrocracking step e) making it possible to obtain at least one gaseous fraction 15 comprising hydrogen, a liquid fraction 16 comprising compounds having a temperature of boiling below 350 ° C;

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

a step h) of separating the effluent 17 from steam cracking step g) making it possible to recover at least one fraction 18 comprising hydrogen, a fraction 19 comprising ethylene, a fraction 20 comprising propylene and a fraction 21 comprising pyrolysis oil.

The description of Figure 1 above is an exemplary embodiment of the invention which does not limit the invention in any way. Only the main stages are shown in said figures, it is understood that all the equipment necessary for operation is present (tanks, pumps, exchangers, furnaces, columns, etc.). Only the main streams containing hydrocarbons are shown, but it is understood that streams of gas rich in hydrogen (make-up or recycle) can be injected at the inlet of each reactor or catalytic bed or between two reactors or two catalytic beds. Means well known to those skilled in the art of purifying and recycling hydrogen are also used. The hydrogen produced during the steam cracking step is advantageously used in addition to steps a) hydroconversion and / or d) hydrocracking.

According to a variant not shown, at least part of the pyrolysis oil fraction 21 resulting from the separation step h) can be injected upstream of the deasphalting step c) and / or of the d) step. hydrocracking. Advantageously, this variant eliminates the asphaltenes contained in the pyrolysis oil and thus maximizes the production of olefins.

According to a variant not shown, the pyrolysis oil fraction 21 resulting from separation step h) can be separated into at least two fractions, for example into an oil fraction. of light pyrolysis which is sent at least in part to hydrocracking stage d), and to a heavy pyrolysis oil fraction which is sent at least in part to hydroconversion stage a) and / or stage c) deasphalting. Advantageously, this variant still makes it possible to maximize the production of olefins. According to a variant not shown, step b) of separating the effluent 3 resulting from hydrotreatment step a) also makes it possible to obtain an atmospheric distillate fraction comprising compounds having a boiling point between 180 and 350 ° C. which can be introduced at least in part in stage d) for extracting the aromatics.

The load treated and the various steps of the process according to the invention are now described in more detail below.

Load

The heavy hydrocarbon feed 1 treated in the process according to the invention is advantageously a hydrocarbon feed containing asphaltenes, and in particular having a C7 asphaltenes content of at least 1.0% by weight, preferably of at least 2.0%. weight in relation to the weight of the load.

Charge 1 has an initial boiling temperature of at least 180 ° C, preferably at least 350 ° C and more preferably at least 540 ° C and a final boiling temperature of at least 600 ° C.

The hydrocarbon feedstock 1 according to the invention can be chosen from atmospheric residues, vacuum residues from direct distillation, crude oils, topped crude oils, tar sands or their derivatives, bituminous shales or their derivatives, oils. of parent rock or their derivatives, taken alone or as a mixture. In the present invention, the feeds treated are preferably atmospheric residues or vacuum residues, or mixtures of these residues, and more preferably vacuum residues.

The heavy hydrocarbon feed treated in the process may contain, among other things, sulfur impurities. The sulfur content can be at least 0.1% by weight, at least 0.5% by weight, preferably at least 1.0% by weight, more preferably at least 2.0% by weight relative to the weight of the load. The heavy hydrocarbon feed treated in the process may contain, inter alia, metals. The nickel and vanadium content may be at least 20 ppm, preferably at least 50 ppm based on the weight of the feed.

The heavy hydrocarbon feed treated in the process may contain, inter alia, Conradson carbon. The Conradson carbon content can be at least 2.0% by weight, preferably at least 5.0% by weight based on the weight of the filler.

These fillers can advantageously be used as they are. Alternatively, said charges can be mixed with at least one co-charge.

Preferably, several co-fillers can be used at different stages of the process according to the invention in order to modulate the viscosity of the charge introduced at each of the stages. A co-charge can be introduced upstream of at least one reactor of hydroconversion stage a). This co-charge can be a hydrocarbon fraction or a mixture of lighter hydrocarbon fractions, which can preferably be chosen from the products resulting from a fluid bed catalytic cracking process (FCC or “Fluid Catalytic Cracking” according to the English terminology). Saxon), in particular a light cut (LCO or "light cycle oil" according to Anglo-Saxon terminology), a heavy cut (FICO or "heavy cycle oil" according to Anglo-Saxon terminology), a decanted oil, a residue of FCC . This co-charge can also be an atmospheric gas oil fraction or a vacuum gas oil fraction obtained by atmospheric or vacuum distillation of a crude oil or of an effluent from a conversion process such as coking or visbreaking or resulting from stages c) and / or e) of separation. This co-charge does not represent more than 20% by weight of the heavy hydrocarbon feed 1.

In accordance with the invention, a hydroconversion step a) is carried out in an ebullating bed reactor in which the heavy hydrocarbon feed 1 or the feed mixture, in the presence of hydrogen, are brought into contact with a hydroconversion catalyst. Advantageously, the load or the mixture of loads is introduced in step a) in the presence of a co-load.

By hydroconversion is meant all the reactions carried out making it possible to reduce the size of the molecules, mainly by cleavage of carbon-carbon bonds, by the action of hydrogen in the presence of a catalyst. During the hydroconversion step, hydrotreatment and hydrocracking reactions take place in particular.

Preferably, the hydroconversion stage comprises one or more three-phase reactors with an upward flow of liquid and gas containing at least one hydroconversion catalyst, the ebullating bed reactors possibly being arranged in series and / or in parallel, typically operating using the technology and under the conditions of the H-Oil ™ process as described for example in US Patents 4,521, 295 or US 4,495,060 or US 4,457,831 or US 4,354,852, or in the article AlChE, March 19-23 , 1995, Houston, Texas, paper number 46d, "Second generation ebullated bed technology", or in chapter 3.5 "Hydroprocessing and Hydroconversion of Residue Fractions" of the book "Catalysis by Transition Métal Sulphides", edited by Éditions Technip in 2013. Each reactor advantageously comprises a recirculation pump allowing the catalyst to be maintained in an ebullating bed by continuous recycling of at least part of a liquid fraction advantageously withdrawn at the head of the re actor and reinjected at the bottom of the reactor.

The hydroconversion step a) is carried out under conditions making it possible to obtain a liquid effluent with a reduced content of sulfur, Conradson carbon, metals, and nitrogen.

Advantageously, step a) is preferably carried out under an absolute pressure of between 2 MPa and 38 MPa, more preferably between 5 MPa and 25 MPa and even more preferably between 6 MPa and 20 MPa, at a temperature of between 300 ° C and 550 ° C, more preferably between 350 ° C and 500 ° C and in a preferred manner between 370 ° C and 450 ° C. The hourly space velocity (WH) relative to the volume of each three-phase reactor is preferably between 0.05 h ¹ and 10 h ¹ . According to a preferred implementation, the WH is between 0.1 h ¹ and 10 h ¹ , more preferably between 0.1 h ¹ and 5.0 h ¹ and even more preferably between 0.15 h ¹ and 2.0 hrs ¹ . According to another implementation, the WH is between 0.05 h ¹ and 0.09 h ¹ . The quantity of hydrogen mixed with the feed is preferably between 50 and 5000 normal cubic meters (Nm ³ ) per cubic meter (m ³ ) of liquid feed, preferably between 100 and 2000 Nm ³ / m ³ and preferably very preferred between 200 and 1000 Nm ³ / m ³ .

The hydroconversion catalyst used in the hydroconversion step a) of the process according to the invention may contain one or more elements from groups 4 to 12 of the periodic table of the elements, which may or may not be deposited on a support. One can advantageously use a catalyst comprising a support, preferably amorphous, such as silica, alumina, silica-alumina, titanium dioxide or combinations of these structures, and very preferably alumina.

The catalyst may contain at least one non-noble group VIII metal chosen from nickel and cobalt, and preferably nickel, said group VIII element being preferably used in combination with at least one group VIB metal chosen from group VIII. molybdenum and tungsten, and preferably the group VIB metal is molybdenum.

In the present description, the groups of chemical elements are given according to the CAS classification (CRC Handbook of Chemistry and Physics, editor CRC press, editor-in-chief D.R. Lide, 81 st edition, 2000-2001). For example, group VIII according to the CAS classification corresponds to the metals of columns 8, 9 and 10 according to the new IUPAC classification.

Advantageously, the hydroconversion catalyst used in the hydroconversion step a) comprises an alumina support and at least one metal from group VIII chosen from nickel and cobalt, preferably nickel, and at least one metal from group VIB chosen from molybdenum and tungsten, preferably molybdenum. Preferably, the hydroconversion catalyst comprises nickel as a group VIII element and molybdenum as a group VIB element.

The content of non-noble group VIII metal, in particular nickel, is advantageously between 0.5% to 10.0% expressed by weight of metal oxide (in particular of NiO), and preferably between 1, 0% to 6.0% by weight, and the content of metal from group VIB, in particular molybdenum, is advantageously between 1.0% and 30% expressed by weight of metal oxide (in particular of molybdenum trioxide Mo0 ₃ ), and preferably between 4% and 20% by weight. The metal contents are expressed as a percentage by weight of metal oxide relative to the weight of the catalyst.

This catalyst is advantageously used in the form of extrudates or beads. The balls have for example a diameter of between 0.4 mm and 4.0 mm. The extrudates have for example a cylindrical shape with a diameter of between 0.5 and 4.0 mm and a length of between 1.0 and 5.0 mm. The extrudates can also be objects of a different shape such as trilobes, regular or irregular tetralobes, or other multilobes. Catalysts of other forms can also be used. The size of these different forms of catalyst can be characterized using the equivalent diameter. The equivalent diameter is defined by 6 times the ratio between the volume of the particle and the outer surface of the particle. The catalyst used in the form of extrudates, beads or other forms therefore has an equivalent diameter of between 0.4 mm and 4.4 mm. These catalysts are well known to those skilled in the art.

In one of the implementations of the process according to the invention, a different hydroconversion catalyst is used in each reactor of this initial hydroconversion stage (a ^, the catalyst offered to each reactor being adapted to the load sent to this reactor.

In one of the implementations of the process according to the invention, several types of catalyst are used in each reactor.

In one of the implementations of the process according to the invention, each reactor contains one or more catalysts suitable for ebullating bed operation.

As is known, and for example described in patent FR 3 033 797, the hydroconversion catalyst, when it is used, can be partly replaced by fresh catalyst, and / or used catalyst but with catalytic activity. greater than the used catalyst to be replaced, and / or regenerated catalyst, and / or rejuvenated catalyst (catalyst from a rejuvenation zone in which most of the deposited metals are removed, before sending the spent and rejuvenated catalyst to a regeneration zone in which the carbon and sulfur which it contains are removed, thus increasing the activity of the catalyst), by withdrawing the used catalyst preferably at the bottom of the reactor, and by introducing the replacement catalyst either at the top or at the bottom of the reactor. This replacement of used catalyst is preferably carried out at regular time intervals, and preferably by puff or almost continuously. The replacement of spent catalyst can be done in whole or in part with used and / or regenerated and / or rejuvenated catalyst obtained from the same reactor and / or from another reactor of any hydroconversion stage. The catalyst can be added with the metals in the form of metal oxides, with the metals in the form of metal sulfides, or after preconditioning. For each reactor, the rate of replacement of the spent hydroconversion catalyst with fresh catalyst is advantageously between 0.01 kg and 10 kg per cubic meter of feed treated, and preferably between 0.1 kg and 3 kg per cubic meter. load processed. This racking and this replacement are carried out using devices advantageously allowing the continuous operation of this hydroconversion step.

As regards the replacement at least in part by regenerated catalyst, it is possible to send the spent catalyst withdrawn from the reactor to a regeneration zone in which the carbon and sulfur which it contains are removed, then this catalyst can be returned. regenerated in the hydroconversion step. With regard to the replacement at least in part by rejuvenated catalyst, it is possible to send the spent catalyst withdrawn from the reactor to a rejuvenation zone in which most of the deposited metals are removed, before sending the spent catalyst. and rejuvenated in a regeneration zone in which the carbon and sulfur which it contains are removed, and then this regenerated catalyst is returned to hydroconversion stage a).

Hydroconversion step a) is characterized by a degree of conversion of the compounds boiling above 540 ° C greater than 50% by mass, preferably greater than 70% by mass.

The effluent 3 obtained at the end of hydroconversion step a) comprises at least one heavy liquid fraction 5 also called the residue liquid fraction and a gaseous fraction 4 containing the gases, in particular H ₂ , H ₂ S, NH ₃ , and hydrocarbons in CC ₄ (that is to say comprising from 1 to 4 carbon atoms).

In accordance with the invention, the process comprises a step b) of separation of the effluent 3 resulting from the hydroconversion step a) into a gas fraction 4, a fraction 1 1 comprising compounds having a boiling point included between 350 and 540 ° C and at least one residual liquid fraction comprising compounds having a boiling point of at least 540 ° C.

The gas fraction 4 can be separated from the effluent 3 using separation devices well known to those skilled in the art, in particular using one or more separator flasks which can operate at different pressures and temperatures, optionally. associated with a steam or hydrogen stripping means and one or more distillation columns. After optional cooling, this gas fraction 4 is preferably treated in a means for purifying hydrogen so as to recover the hydrogen not consumed during the hydroconversion reactions. The purified hydrogen can then advantageously be recycled in the process according to the invention. The hydrogen can be recycled to the inlet and / or to different places of stage a) of hydroconversion and / or of stage d) of hydrocracking in an ebullating bed.

Step b) of separation comprises a vacuum distillation in which the effluent 3 from step a) is fractionated by vacuum distillation into at least one vacuum distillate fraction 1 1 and at least one vacuum residue fraction 5 The vacuum distillate fraction 1 1 comprises fractions of the vacuum gas oil type, that is to say compounds having a boiling point between 350 and 540 ° C. 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 540 ° C.

Preferably, step b) of separation firstly comprises atmospheric distillation, that is to say upstream of vacuum distillation, in which the liquid hydrocarbon fraction (s) ( s) obtained after separation is (are) fractionated by atmospheric distillation into at least one atmospheric distillate fraction and at least one atmospheric residue fraction, then vacuum distillation in which the atmospheric residue fraction obtained after atmospheric distillation is fractionated by vacuum distillation into at least one vacuum distillate fraction 1 1 and at least one vacuum residue fraction 5.

Advantageously, the separation step b) further comprises at least one atmospheric distillation upstream from the vacuum distillation, in which the effluent 3 is fractionated by atmospheric distillation into at least one distillate fraction containing naphtha, that is - ie comprising compounds having a boiling point between 80 and 180 ° C, and a distillate fraction containing diesel, ie comprising compounds having a boiling point between 180 and 350 ° vs.

Advantageously, the distillate fraction containing naphtha is at least partially and preferably entirely sent to step g) of steam cracking. The diesel-containing distillate fraction can be at least in part and preferably in full sent to step d) of extraction. The diesel-containing distillate fraction can optionally be sent in part to hydrocracking step e).

At least part, and preferably all, of the vacuum residue fraction 5 is sent to deasphalting step c). At least part, and preferably all, of the vacuum distillate fraction 11 is sent to step d) for extracting the aromatics.

According to the invention, the process comprises a step c) of deasphalting by liquid-liquid extraction of the residue fraction 5 from step b) of separation. Said step c) is carried out by liquid-liquid extraction using a solvent or a mixture of solvents 6 making it possible to obtain on the one hand a fraction 7 comprising asphalt, and on the other hand a deasphalted oil fraction (DAO) 8.

Step c) of deasphalting is preferably carried out under specific conditions making it possible to obtain a quality DAO 8, preferably with a low asphaltene content.

Step c) of deasphalting is preferably carried out in a single step using an apolar solvent or a mixture of apolar solvents.

Step c) can be carried out in an extraction column or extractor, or in a mixer-settler. Step c) is preferably carried out in an extraction column containing liquid-liquid contactors (packing elements and / or trays, etc.) placed in one or more zones. Preferably, the solvent or the mixture of solvents 6 is introduced into the extraction column at two different levels. Preferably, the deasphalting feedstock is introduced into an extraction column at a single introduction level, generally mixed with at least part of the solvent or mixture of solvents 6 and generally below a first contactor zone. liquid-liquid. Preferably, the other part of the solvent or mixture of solvents 6 is injected lower than the deasphalting charge, generally below a second zone of liquid-liquid contactors, the deasphalting charge being injected above this second. contactors area.

Step c) is carried out under subcritical conditions, that is to say below the critical point, for said solvent or mixture of solvents 6. Step c) is carried out at a temperature advantageously between 50 and 350 ° C, preferably between 80 and 320 ° C, more preferably between 120 and 310 ° C, even more preferably between 150 and 300 ° C, 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 volume ratio of the solvent or of the mixture of solvents 6 to the mass of residue fraction 5 resulting from step b) is generally between 1/1 and 12/1, preferably between 2/1 and 9/1 expressed in liters per kilograms. This ratio includes all of the solvent or mixture of solvents which can be divided into several injection points.

The apolar solvent used is preferably a solvent composed of saturated hydrocarbon (s) comprising a number of carbons greater than or equal to 3, preferably between 3 and 5. These solvents can be for example propane, butane. or pentane. These solvents are used pure or as a mixture.

Preferably, the solvent 6 used in step c) is an apolar solvent composed of at least 80% by volume of saturated hydrocarbon (s) comprising a number of carbons of between 3 and 7, preferably of between between 4 and 5, so as to maximize the yield of DAO fraction 8.

The choice of the temperature and pressure conditions of the extraction combined with the choice of the nature of the solvents 6 in deasphalting step c) make it possible to adjust the extraction performance. Step c) can make it possible, thanks to these specific deasphalting conditions, to precipitate in the asphalt fraction 7 an adjusted amount of polar structures of heavy resin and asphaltene type, which makes it possible to obtain an asphalt fraction 7 with a moderate yield. , generally less than 40%, or even less than 30% relative to the amount of compounds having a boiling point greater than 540 ° C. at the inlet of deasphalting step c). The high yield of DAO 8 makes it possible to obtain more cracked products at the outlet of step g) of steam cracking. The DAO 8 fraction obtained comprises less than 2000 ppm of C7 asphaltenes, generally less than 1000 ppm of C7 asphaltenes, or even less than 500 ppm of C7 asphaltenes.

At the head of the extraction column or of the mixer-settler, preferably above the liquid-liquid contactor (s) zone located at the highest position, a fraction is recovered which comprises the DAO 8 and a part solvent or mixture of solvents.

At the bottom of the extraction column or of the mixer-settler, preferably below the contactor zone (s) located at the lowest position, a fraction 7 is recovered which comprises asphalt and part of the solvent. or mixture of solvents.

The solvent or mixture of solvents 6 may consist of an makeup and / or a part recycled during separation steps. These additions advantageously allow compensate for the losses of solvent in the asphalt fraction 7 and / or in the DAO fraction 8, due to the separation steps.

Step c) of deasphalting comprises an integrated sub-step of separation of fraction 8 comprising the DAO and the solvent or mixture of solvents. The solvent or mixture of solvents recovered can be recycled in step c) of deasphalting. This integrated separation sub-step making it possible to separate the DAO 8 and the solvent or the mixture of solvents can use all the necessary equipment known to those skilled in the art (separator flasks, distillation or stripping columns, heat exchangers, etc. furnaces, pumps, compressors, etc.). At least part, and preferably all, of the DAO 8 is sent to step d) of extracting aromatics.

Step d) of extracting the aromatics

According to the invention, the process comprises a step d) of extracting the aromatics from at least a part of the deasphalted oil fraction 8 from step c) of deasphalting. Said step making it possible to obtain an extract fraction 13 and a raffinate fraction 10.

Advantageously, at least part, preferably all, of the distillate fraction comprising compounds having a boiling point of between 180 and 350 ° C resulting from stage b) of separation, is also introduced in stage d ) extraction of aromatics.

Optionally, part of fraction 11 from step b) of separation and comprising compounds having a boiling point of between 350 and 540 ° C can be introduced in step d) of extraction.

The objective of the aromatics extraction step is to extract at least part of the aromatic compounds, by liquid-liquid extraction using a polar solvent 9, as well as the resins contained in the DAO fraction 8.

Preferably, the extraction of the aromatics is carried out on fractions having a boiling point higher than 180 ° C and preferably higher than 350 ° C, in order to avoid losses of yield of light fractions during the recovery of the solvent after extraction.

The compounds extracted during step d) preferably have a boiling point greater than the boiling point of the solvent, which advantageously makes it possible to maximize the yield during the separation of the solvent from the raffinate after the extraction. In addition, the recovery of the solvent is also more efficient and economical.

As a solvent, furfural, N-methyl-2-pyrrolidone (NMP), sulfolane, dimethylformamide (DMF), dimethylsulfoxide (DMSO), phenol, or a mixture of these solvents in equal proportions or different. Preferably, the solvent is furfural. The operating conditions are generally a solvent / feed ratio of step d) of 1/2 to 6/1, preferably from 1/1 to 4/1, a temperature profile between ambient temperature and 150 ° C, preferably between 50 and 150 ° C. The pressure is between atmospheric pressure and 2.0 MPa, preferably between 0.1 and 1.0 MPa.

The liquid / liquid extraction can generally be carried out in a mixer-settler or in an extraction column operating in counter-current. Preferably, the extraction is carried out in an extraction column.

The chosen solvent has a sufficiently high boiling point to be able to fluidify the charge of step d) without vaporizing.

After contact of the solvent, with the effluent introduced in step d), two fractions are obtained at the end of step d), an extract fraction 13, consisting of parts of the heavy fraction not soluble in the solvent ( and highly concentrated in aromatics) and a raffinate fraction 10, consisting of the solvent and the soluble parts of the heavy fraction. The solvent is separated from the soluble parts by distillation and recycled internally to the liquid / liquid extraction process. The separation of the extract and the raffinate and the recovery of the solvent are carried out in a separation sub-step integrated in step d) of extracting the aromatics.

Stage e) of hvdrocraquaqe in a fixed bed

According to the invention, the process comprises a stage e) of hydrocracking in a fixed bed of at least part of the fraction 11 resulting from stage b) of separation and at least one part of the extracted fraction 13 from extraction step d) in the presence of a hydrocracking catalyst.

Hydrogen 12 can also be injected upstream of the various catalytic beds making up the hydrocracking reactor (s). Along with the hydrocracking reactions desired in this step, any type of hydrotreatment reaction (HDM, HDS, HDN, etc.) also occurs. Hydrocracking reactions leading to the formation of atmospheric distillates take place with a degree of conversion of the vacuum distillate to atmospheric distillate which is generally greater than 30%, typically between 30 and 50% for mild hydrocracking and greater than 80% for extensive hydrocracking. Specific conditions, particularly temperature, and / or the use of one or more specific catalysts, promote the desired hydrocracking reactions.

Hydrocracking step e) according to the invention is carried out under hydrocracking conditions. It can advantageously be carried out at a temperature between 340 and 480 ° C, preferably between 350 and 430 ° C and under an absolute pressure between 5 and 25 MPa, preferably between 8 and 20 MPa, preferably between 10 and 18 MPa. The temperature is usually adjusted depending on the desired level of hydrotreatment and the duration of the intended treatment. Most often, the space velocity of the hydrocarbon feed, commonly called WH, and which is defined as being the volumetric flow rate of the feed divided by the total volume of the catalyst, can be in a range from 0.1 to 3, 0 h ¹ , preferably from 0.2 to 2.0 h ¹ , and more preferably from 0.25 to 1.0 h ¹ . The quantity of hydrogen mixed with the feed can be between 100 and 5000 normal cubic meters (Nm ³ ) per cubic meter (m ³ ) of liquid feed, preferably between 200 and 2000 Nm ³ / m ³ , and more preferably between 300 and 1500 Nm ³ / m ³ . Hydrocracking step e) can be carried out industrially in at least one reactor with a downward flow of liquid.

Hydrocracking stage e) preferably comprises two catalytic sections in series, with an upstream hydrotreatment catalytic section so as to limit the deactivation of the downstream hydrocracking catalytic section. This hydrotreatment section aims in particular to significantly reduce the nitrogen content of the feed, the nitrogen being an inhibitor of the acid function of the bifunctional catalysts of the hydrocracking catalytic section. Hydrocracking stage e) can also comprise a second catalytic hydrocracking section treating at least one heavy cut resulting from a separation stage. The catalysts in hydrocracking step e) used can be hydrotreatment and hydrocracking catalysts.

The hydrotreatment catalysts used can be hydrotreatment catalysts consisting of a support of inorganic oxide type (preferably an alumina) and of an active phase comprising chemical elements from group VIII (Ni, Co, etc.) and group VI (Mo, etc.).

The hydrocracking catalysts can advantageously be bifunctional catalysts, having a hydrogenating phase in order to be able to hydrogenate the aromatics and to achieve the equilibrium between the saturated compounds and the corresponding olefins and an acid phase which makes it possible to promote the hydroisomerization reactions. and hydrocracking. The acid function is advantageously provided by supports with large surfaces (generally 100 to 800 m ² .g ¹ ) having a surface acidity, such as halogenated aluminas (chlorinated or fluorinated in particular), combinations of oxides of boron and of aluminum, amorphous silica-aluminas and zeolites. The hydrogenating function is advantageously provided either by 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 by a combination of 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 cobalt). Preferably, the bifunctional catalyst used comprises at least one metal chosen from the group formed by the metals of groups VIII and VIB, taken alone or as a mixture, and a support comprising 10 to 90% by weight of a zeolite and 90 to 10% weight of inorganic oxides. The metal from group VIB used is preferably chosen from tungsten and molybdenum and the metal from group VIII is preferably chosen from nickel and cobalt. According to another preferred variant, monofunctional catalysts and bifunctional catalysts of the alumina, silica-amorphous or zeolitic alumina type can be used as a mixture or in successive layers.

Preferably, the catalytic volume used during the second stage e) of hydrocracking consists of at least 30% of hydrocracking catalysts of the bifunctional type.

Optionally, a co-feed (not shown) can be injected upstream of any catalytic bed of hydrocracking section d). This co-charge is typically a vacuum distillate resulting from direct distillation or resulting from a conversion process, or a deasphalted oil.

Preferably, hydrocracking step e) is carried out in "maxi naphtha" mode, that is to say it makes it possible to obtain a yield of liquid compounds having a boiling point of less than 220 ° C. greater than 50% by weight of the feedstock at the inlet of hydrocracking stage e).

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

Step f) separation of the hydrocraquaqe effluent in a fixed bed

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

Said effluent 14 is advantageously separated in at least one separating flask 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 using any known separation devices of the invention. a person skilled in the art, such as one or more separator flasks which can operate at different pressures and temperatures, optionally associated with a means for stripping with steam or with hydrogen and with one or more distillation columns. These separators can for example be high pressure high temperature (HPHT) separators and / or high pressure low temperature (HPBT) separators.

The gas fraction 15 obtained at the end of stage e) of separation comprises gases, such as H ₂ , H ₂ S, NH ₃ , and C1 -C4 hydrocarbons (such as methane, ethane, propane, etc. butane). Advantageously, the hydrogen contained in the gas fraction 15 is purified and recycled in any one of the steps a) of hydroconversion in an ebullating bed and / or e) of hydrocracking in a fixed bed. In a particular embodiment, the purification of the hydrogen contained in the gaseous fraction 15 can be carried out simultaneously with the treatments of the gaseous fractions resulting from the separation of the effluents from stages a) of hydroconversion in an ebullating bed and e) of hydrocracking. in a fixed bed. The purification of the hydrogen can be carried out by washing with amines, a membrane, a PSA (Pressure Swing Adsorption) type system, or several of these means arranged in series. In a preferred embodiment, the separation step f) further comprises gas-liquid separation or the succession of separation devices, at least one atmospheric distillation, in which the hydrocarbon fraction (s) ) liquid (s) obtained after separation is (are) fractionated by atmospheric distillation into at least one atmospheric distillate fraction 16 comprising compounds having a boiling point of less than 350 ° C and optionally a liquid fraction comprising vacuum distillate comprising compounds having a boiling point greater than 350 ° C. At least a part, and preferably all, of the atmospheric distillate fraction 16 and optionally of the fraction comprising vacuum distillate is advantageously sent to step g) of steam cracking.

Optionally, at least part of the vacuum distillate type fraction is recycled to hydrocracking step e), and according to this variant it may be necessary to perform a purge consisting of unconverted fractions of the vacuum distillate type of so as to deconcentrate the polyaromatic species and to limit the deactivation of the hydrocracking catalyst of step e). In order to limit the purge and thus increase the overall conversion, it may be advantageous to optionally carry out this purge by sending at least part of the unconverted fraction of vacuum distillate type at the input of step c) of deasphalting of so as to at least partly eliminate the polyaromatic species in the asphalt fraction 7.

According to the invention, the process comprises a step g) of steam cracking of the raffinate fraction 10 resulting from the extraction step d) and of the liquid fraction 16 resulting from the separation step f) comprising compounds having a boiling point lower than 350 ° C, and preferably a fraction comprising compounds having a boiling point higher than 350 ° C resulting from stage f) of separation.

Optionally, part of the fraction comprising compounds having a boiling point between 80 and 180 ° C resulting from step b) of separation can be introduced in step g) of steam cracking.

Step g) of steam cracking is advantageously carried out in at least one pyrolysis furnace at a temperature between 700 and 900 ° C, preferably between 750 and 850 ° C, and under a pressure between 0.05 and 0.3 Relative MPa. The residence time of hydrocarbons is generally less than or equal to 1.0 seconds (denoted s), preferably between 0.1 and 0.5 s. Advantageously, water vapor is 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 hydrocarbons entering step g). Preferably, step g) is carried out in several pyrolysis ovens in parallel so as to adapt the operating conditions to the different flows feeding step g) and resulting from steps b), e), f) and h), and also to manage the decoking times of the tubes. A furnace comprises one or more tubes arranged in parallel. A furnace can also refer to a group of furnaces operating in parallel. Thus one furnace can be dedicated to cracking fractions rich in ethane, another furnace dedicated to cuts rich in propane and butane, another furnace dedicated to cuts comprising compounds having a boiling point between 80 and 180 ° C, a another oven dedicated to cuts comprising compounds having a boiling point of between 180 and 350 ° C, and another oven dedicated to cuts comprising compounds having a boiling point greater than 350 ° C.

Preferably, the method comprises a step h) of separating the effluent 17 from steam cracking step g) making it possible to obtain at least one fraction 18 comprising, preferably consisting of, hydrogen, a fraction 19 comprising, preferably consisting of ethylene, a fraction 20 comprising, preferably consisting of, propylene and a fraction 21 comprising, preferably consisting, and pyrolysis oil. Optionally, step h) of separation also makes it possible to recover a fraction comprising, preferably consisting of butenes and a fraction comprising, preferably consisting of pyrolysis gasoline.

Preferably, the cuts rich in saturated compounds resulting from the light gases or from the pyrolysis gasoline resulting from the separation stage h) can be recycled to the steam cracking stage g), in particular ethane and propane, of so as to increase the yield of ethylene and propylene.

The pyrolysis oil fraction 21 can optionally be subjected to an additional separation step so as to obtain several fractions, for example a light pyrolysis oil comprising compounds having a boiling point of less than 350 ° C. and a heavy pyrolysis oil. comprising compounds having a boiling point greater than 350 ° C. The light pyrolysis oil can advantageously be injected upstream of hydrocracking step d). The heavy pyrolysis oil can advantageously be injected upstream of stage a) of hydroconversion and / or of stage c) of deasphalting. Advantageously, the separation of fraction 21 into two fractions and their recycling in one of steps a), c) or e) of the process making it possible to maximize the formation of olefins from heavy hydrocarbon feedstocks.

EXAMPLE

The example below illustrates a particular implementation of the method according to the invention without limiting its scope.

The heavy hydrocarbon feedstock 1 treated in the process is a vacuum residue originating from the Middle East and having the properties shown in Table 1.

Table 1: properties of the load

The feed is subjected to a hydroconversion step a) in two ebullating bed reactors in series and in the presence of an ebullating bed hydroconversion catalyst of NiMo type on alumina under the conditions indicated in Table 2.

Table 2: conditions of step a) of ebullated bed hydroconversion

The effluent 3 from step a) of ebullated bed hydroconversion is subjected to a step b) of separation comprising separator flasks as well as an atmospheric distillation column and a vacuum distillation column. The yields of the different fractions obtained after separation are shown in Table 3 (% mass relative to the feed upstream of step a) of ebullating bed hydrocracking, noted% m / m):

Table 3: Yields of hydroconversion step a) after separation in step b)

Fraction 5 (540 ° C +) of vacuum residue type is sent to a deasphalting step c) carried out in an extraction column operating continuously under the conditions presented in Table 4:

Table 4: conditions of the deasphalting step

At the end of deasphalting step c), a DAO 8 fraction is obtained with a yield of 62% and a pitch fraction is obtained with a yield of 38%; these yields are related to the charge of the deasphalting step corresponding to fraction 5 (540 ° C +) from step b) of separation of the effluent from step a) from hydrocracking.

The DAO fraction 8 from step c) of deasphalting, the fraction (180-350 ° C) and the fraction 11 (350-540 ° C) from step b) of separation are sent to a step d ) extraction of aromatics carried out in a mixer-settler, the conditions of which are presented in Table 5:

Table 5: conditions of extraction step d) At the end of the aromatics extraction step, a raffinate fraction 10 depleted in aromatics is obtained with a yield of 56.2% and an extract fraction 13 enriched in aromatics is obtained with a yield of 43.8%; these yields are related to the total charge, that is to say all the fractions introduced in stage d) of extraction of the aromatics

The extracted fraction 13 from step d) of extracting the aromatics is sent to a step e) of fixed bed hydrocracking carried out under the conditions presented in Table 6:

Table 6: conditions of stage e) of fixed bed hydrocracking

The effluent 14 resulting from fixed-bed hydrocracking stage e) is subjected to a separation stage comprising separator flasks and an atmospheric distillation column. The yields of the different fractions obtained after separation are shown in Table 7 (% mass relative to the feedstock upstream of the fixed bed hydrocracking stage, noted% m / m):

Table 7: yields of fixed bed hydrocracking step e)

after separation in step f).

The liquid fractions PI-220 ° C, 220-350 ° C and 350 ° C + from step f) of separation of the effluent from the fixed bed hydrocracking step, the PI-180 ° C fraction from of stage a) of hydrocracking in an ebullating bed and the raffinate fraction 10 resulting from stage d) of extraction of the aromatics are sent to a stage g) of steam cracking where each of the liquid fraction is cracked under different conditions ( table 8).

Table 8: conditions of the steam cracking step The effluents from the various steam cracking furnaces are subjected to a separation step making it possible to recycle the saturated compounds and to obtain the yields presented in Table 9 (% by mass relative to the total load upstream of step g) of steam cracking , noted% m / m).

Table 9: yields of the steam cracking step

Table 9 shows the yields of steam cracking products. Compared to the atmospheric residue type feed introduced in hydroconversion step a), the process according to the invention makes it possible to achieve mass yields of ethylene and propylene of 29.4% and 16.0% respectively. In addition, the specific sequence of steps upstream of the steam cracking step helps limit the formation of coke.

Claims

1. Process for producing olefins from a hydrocarbon feed (1) having a sulfur content of at least 0.1% by weight, an initial boiling point of at least

180 ° C and a final boiling point of at least 600 ° C, said process comprising the following steps:

a) a hydroconversion step carried out in an ebullating bed reactor in which said heavy hydrocarbon feed (1) in the presence of hydrogen (2) is brought into contact with a hydroconversion catalyst, said step making it possible to obtain d an effluent (3);

b) a step of separating the effluent (3) from step a) hydroconversion into a gas fraction (4), a fraction (1 1) comprising compounds having a boiling point between 350 and 540 ° C and a residual liquid fraction under vacuum (5) comprising compounds having a boiling point of at least 540 ° C,

c) a deasphalting step by liquid-liquid extraction of the residue fraction under vacuum (5) resulting from the separation step b), said step c) being carried out by means of a solvent (6) or of a mixture of solvents making it possible to obtain on the one hand a fraction (7) comprising asphalt, and on the other hand a deasphalted oil fraction (8),

d) a step of extracting the aromatics from at least part of the deasphalted oil fraction (8) from step c) of deasphalting and at least part of the fraction (1 1) from the step b) of separation, making it possible to obtain an extract fraction (13) and a raffinate fraction (10),

e) a step e) of hydrocracking in a fixed bed of at least part of the extracted fraction (13) resulting from the extraction step d) in the presence of hydrogen (12) of a hydrocracking catalyst , making it possible to obtain an effluent (14),

f) a step of separating the effluent (14) from step e) of hydrocracking in a fixed bed into at least one gaseous fraction (15) and at least one liquid fraction (16), g) a step of steam cracking of the raffinate fraction (10) resulting from extraction step d) and of the liquid fraction (16) resulting from separation step f) comprising compounds at a boiling point below 350 ° C, allowing an effluent (17) to be obtained, h) a step of separating the effluent (17) from step g) of steam cracking making it possible to obtain at least one fraction (18) comprising hydrogen, from a fraction (19) comprising ethylene, a fraction (20) comprising propylene and a fraction (21) comprising pyrolysis oil.

2. The method of claim 1 wherein step b) of separation comprises vacuum distillation to obtain at least one vacuum distillate fraction (1 1) and at least one vacuum residue fraction (5).

3. The method of claim 2 wherein step b) of separation comprises upstream of the vacuum distillation, atmospheric distillation to obtain at least one atmospheric distillate fraction and at least one atmospheric residue fraction, said fraction. atmospheric residue being sent to said vacuum distillation making it possible to obtain at least one vacuum distillate fraction (1 1) and at least one vacuum residue fraction (5).

4. Method according to any one of the preceding claims, in which all of the residue fraction (5) from step b) is sent to step c) for deasphalting.

5. Method according to any one of the preceding claims wherein the solvent (6) used in step c) is an apolar solvent composed of at least 80% by volume of saturated hydrocarbon (s) comprising a number of carbon between 3 and 7.

6. The method of claim 3 wherein at least part of a distillate fraction (1 1) from step b) of separation, is introduced in step d) of extraction of aromatics.

7. Process according to any one of the preceding claims, in which step d) of extracting the aromatics is carried out on fractions (8, 1 1) having a boiling point greater than 180 ° C.

8. Process according to any one of the preceding claims, in which the compounds extracted (10, 13) in step d) have a boiling point higher than the boiling point of the solvent (6) used.

9. Process according to any one of the preceding claims, in which step e) of hydrocracking is carried out so as to obtain a yield of liquid compounds having a boiling point of less than 220 ° C greater than 50% by weight of the feedstock at the inlet of hydrocracking stage e).

10. Process according to any one of the preceding claims, in which the separation step f) comprises at least one atmospheric distillation making it possible to obtain at least one atmospheric distillate fraction (16) comprising compounds having a boiling point. lower than 350 ° C and a liquid fraction comprising vacuum distillate comprising compounds having a boiling point higher than 350 ° C.

1 1. The method of claim 10 wherein the atmospheric distillate fraction (16) and the fraction comprising vacuum distillate are sent to step g) of steam cracking.

12. Process according to any one of the preceding claims, in which part of a fraction comprising compounds having a boiling point between 80 and 180 ° C resulting from step b) of separation is introduced in step g ) steam cracking.

13. Process according to any one of the preceding claims, in which step g) of steam cracking is carried out in at least one pyrolysis furnace at a temperature of between 700 and 900 ° C, under a pressure of between 0.05 and 0 , 3 MPa during a residence time less than or equal to 1.0 seconds.

14. Process according to any one of the preceding claims, in which the cuts rich in saturated compounds originating from the light gases or from the pyrolysis gasoline obtained from stage h) of separation are recycled to stage g) of steam cracking.

15. Process according to any one of the preceding claims, in which the pyrolysis oil fraction (21) is subjected to an additional separation step so as to obtain a light pyrolysis oil comprising compounds having a boiling point of less than 350. ° C and a heavy pyrolysis oil comprising compounds having a boiling point greater than 350 ° C, said light pyrolysis oil is injected upstream of hydrocracking step e), and said heavy pyrolysis oil is injected upstream of hydroconversion step a) and / or of deasphalting step c).