FR3027909A1 - INTEGRATED PROCESS FOR THE PRODUCTION OF HEAVY FUEL TYPE FUELS FROM A HEAVY HYDROCARBONNE LOAD WITHOUT INTERMEDIATE SEPARATION BETWEEN THE HYDROTREATING STEP AND THE HYDROCRACKING STEP - Google Patents

Abstract

The present invention describes a method for producing heavy fuel type fuel, which fuel can optionally become a marine fuel, from a heavy hydrocarbon feedstock having a sulfur content of at least 0.5% by weight, a temperature initial boiling point of at least 350 ° C and a final boiling temperature of at least 450 ° C, integrated process using a fixed bed hydrotreating step and a hydrocracking step comprising at least one type reactor hybrid.

Description

FIELD OF THE INVENTION The present invention relates to the refining and the conversion of heavy hydrocarbon fractions containing, inter alia, sulfur-containing impurities. It relates more particularly to a process for treating heavy petroleum feedstocks for the production of fuel oils and oil bases, in particular bunker oil and bunker oil bases, with low sulfur content and low sediment content. EXAMINATION OF THE PRIOR ART The object of the present invention is to produce fuel oils and fuel bases, in particular bunker oil and bunker oil bases, which comply with the recommendations of the MARPOL convention in terms of equivalent sulfur content. and preferably also following the recommendations for sediment content after aging, as described for marine fuels in IS08217. Fuel oils used in maritime transport generally include atmospheric distillates, vacuum distillates, atmospheric residues and vacuum residues from direct distillation or from refining processes, including hydrotreatment and conversion processes, which may be be used alone or mixed.

Another object of the present invention is to produce jointly, by means of the same process, atmospheric distillates (naphtha, kerosene, diesel), vacuum distillates and / or light (C 1 to C 4) gases. The bases of the naphtha and diesel type can be upgraded to refineries for the production of automotive and aviation fuels, such as, for example, super-fuels, Jet fuels and gas oils.

Among the documents of the relevant prior art include: - US7815870 which describes a hydrocracking process with at least one bubbling bed operating with a supported catalyst and a dispersed cat (hybrid mode). In this document there may be in addition to one or more reactors of fixed bed type or "slurry" upstream or downstream, but in all cases, the bubbling bed operates in hybrid mode. But the cited document does not describe the conditions of a sequence with a prior hydrotreatment step for hydrodesulfurization performance and conversion as presented in this application. The document cited also does not describe the post treatment allowing the reduction of the sediment content so as to meet the quality requirements of the bunker oil. US5358629 / US5622616 / US5868923 which describe the injection of cata dispersed in a bubbling bed. The processes described in these texts do not describe upstream hydrotreatment. None of these documents therefore describes the production of a fuel oil or oil bases with very low sulfur content meeting the new recommendations of the International Maritime Organization, and low sediment content as required by the new version of the ISO 8217: 2012 standard. The present invention makes it possible to improve the conversion processes described in the state of the art for the production of fuel oils and bases of low-sulfur fuel oils. It is based on the following sequence of steps: a hydrotreatment step of which at least one of the reactors operates in a fixed bed, a hydrocracking step of said heavy fraction using reactors, one of which at least is of the hybrid type. a step of separating the effluent from the hydrocracking step making it possible to release a heavy cut; an optional step of treating the sediments of said heavy cut. an optional step for separating the effluent from the sediment treatment stage This process is said to be integrated because the high pressure, fixed bed hydrotreating and bubbling bed hydrocracking stages succeed each other without intermediate separation. SUMMARY DESCRIPTION OF THE FIGURES FIG. 1 represents a schematic view of the process according to the invention, showing a hydrotreatment zone, a hydrocracking zone and a separation zone of the effluent of the hydrocracking zone and a zone treatment / separation of sediments contained in the heavy cut from the separation zone of the hydrocracking effluent. For the sake of clarity, the limits of each step have been symbolically represented in FIG. 1: "A" denotes the hydrotreatment zone, "B" denotes the hydrocracking zone and "C" denotes the separation zone of the effluent from the hydrocracking zone and "D" denotes the sediment treatment zone. SUMMARY DESCRIPTION OF THE INVENTION The present invention can be defined as a process for treating a heavy hydrocarbon feed having a sulfur content of at least 0.5% by weight, an initial boiling temperature of at least 350 ° C, and a final boiling temperature of at least 450 ° C, to obtain at least one liquid hydrocarbon fraction having a sulfur content of less than or equal to 0.5% by weight, the process comprising the following successive steps a) a fixed bed hydrotreatment step, wherein the hydrocarbon feedstock and hydrogen are contacted on a hydrotreatment catalyst; b) a step of hydrocracking at least a portion of the heavy fraction; of the effluent from step (a), taken alone or mixed with other residual or fluxing cuts, in at least one reactor operating in hybrid mode, that is to say operating in a bubbling bed with a supported catalyst associated with a "dispersed" analyzer consisting of very fine catalyst particles constituting a suspension with the hydrocarbon liquid phase to be treated, c) a step of separating the effluent from step (b) of hydrocracking to obtain at least a light fraction and at least one heavy fraction, said heavy fraction constituting the liquid hydrocarbon fraction announced in the preamble, d) an optional step of treating the heavy fraction resulting from step c) making it possible to reduce the sediment content of said heavy fraction, e) an optional step of final separation of the effluent from the treatment step d) to obtain said sediment-reduced liquid hydrocarbon fraction. The process of the present invention is qualified as integrated because it excludes any gas-liquid separation intermediate between the hydrotreatment step a) and the hydrocracking step b). An ebullating bed can be defined as a fluidized solid liquid gas bed in which the catalyst particles have a size of between 0.5 and 1.5 mm, preferably between 0.8 mm and 1.2 mm, and preferably still more preferably between 0.9 mm and 1.1 mm.

A hybrid type of bed corresponds to a bubbling bed in which an additional injection of a dispersed catalyst was made. A dispersed catalyst is a catalyst in the form of very fine particles, that is to say generally of a size of between 1 nanometer (ie 10-9 m) and 150 micrometers, preferably between 0.1 and 100 micrometers, and even more preferably between 10 and 80 microns. A hybrid bed thus comprises two populations of catalyst, a population of bubbling bed catalyst to which is added a population of dispersed type catalyst. The HCAT® technology marketed by the company HTI is an example of implementation of dispersed catalyst injected into a bubbling bed reactor. The process for treating a heavy hydrocarbon feedstock according to the present invention can be broken down into several variants. In a first variant, the hydrocracking step b) comprises a first bubbling bed reactor followed by a second "hybrid" type bed reactor (that is to say of the bubbling bed type with injection of a catalyst). "dispersed" type). In a second variant, the hydrocracking step b) comprises a first hybrid bed type reactor followed by a second hybrid type reactor. In a third variant, the hydrocracking step b) comprises a single hybrid bed type reactor. The process for treating a heavy hydrocarbon feedstock according to the present invention comprises a step a) of hydrotreatment in a fixed bed operated under the following conditions: a temperature of between 300 ° C. and 500 ° C., preferably between 350 ° C. C and 420 ° C, an absolute pressure between 2 MPa and 35 MPa, preferably between 11 MPa and 20 MPa, a space velocity of the hydrocarbon feedstock, commonly called VVH, which is defined as the volumetric flow of the load taken at the conditions of the process divided by the total volume of the reactor, in a range from 0.1 h -1 to 5 h -1, preferably 0.1 h -1 to 2 h -1, and more preferably 0 , 1 h-1 to 0.45 h-1, a quantity of hydrogen mixed with the feedstock of between 100 and 5000 normal cubic meters (Nm3) per cubic meter (m3) of liquid feedstock, preferably between 200 Nm3 / m3 and 2000 Nm3 / m3, and more preferably between 300 Nm3 / m3 and 1500 Nm3 / m3.

The process according to the present invention also uses a hydrocracking step b) treating at least one heavy fraction resulting from the separation of the effluent from the hydrotreating step. This hydrocracking step comprises at least one hybrid-type reactor, this reactor generally operating under the following conditions: a pressure of 2 to 35 MPa, preferably 10 to 25 MPa, a hydrogen partial pressure ranging from 2 to 35 MPa and preferably from 10 to 25 MPa, a temperature of between 330 ° C. and 550 ° C., preferably from 350 ° C. to 500 ° C., more preferably between 370 ° C. and 480 ° C., an hourly space velocity (VVH). reactor, ie ratio between the volume flow rate of charge and the reactor volume) of between 0.1 and 10 h -1, preferably of 0.1 h to 5 h -1 and more preferably between 0.1 and 2 h -1. h-1, a hourly space velocity "bubbling bed catalysts" for boiling bed or hybrid reactors between 0.1 and 5 h -1, preferably from 0.1 h to 3 h -1 and more preferably between 0 , 1 and 1 h-1, the VVH "bubbling bed catalyst being defined as the ratio between the volumetric flow rate that of load in m3 / h and the volume in m3 of bubbling bed catalyst at rest, that is to say when the expansion rate of the bubbling bed is zero, a content of metal compounds in the catalysts used in hybrid bed between 0 and 10% by weight, preferably between 0 and 1% by weight, said content being expressed as a weight percentage of metal elements of group VIII and / or of the VIE group, a hydrogen / charge ratio of between 50 and 5000 Nm3 / m3, preferably between 100 and 1500 Nm3 / m3 with a still preferred range between 500 and 1300 Nm3 / m3.

In a variant of the process for treating a heavy hydrocarbon feedstock according to the invention, the said liquid hydrocarbon fraction resulting from the separation step c) is furthermore subjected to a treatment step d) making it possible to treat and separate sediments and residues from catalysts, by maturation converting potential sediments into existing sediments, and physical separation allowing the elimination of all existing sediments. In another variant of the process for treating a heavy hydrocarbon feedstock according to the present invention, said liquid hydrocarbon fraction is furthermore subjected to a step of recovering the "dispersed" catalyst in addition to the treatment step d), which makes it possible to treat and separate sediments and catalyst residues. Step c) of separation of the effluent from the hydrocracking step can be carried out either in a summary manner, allowing one or two liquid fractions to be obtained, or in a more complete manner, thus making it possible to obtain at least three liquid fractions. The separation c) carried out in a more complete manner thus makes it possible to obtain well-separated atmospheric and / or vacuum distillate cuts (naphtha, kerosene, gas oil, vacuum gas oil, for example) from the atmospheric residue and / or under vacuum. The manner in which this separation step is performed conditions the sequence of optional steps d) and e). The treatment step d) makes it possible to convert the potential sediments contained in the heavy fraction resulting from the upstream separation c), by maturation, into existing sediments, and then to separate them from the liquid fraction. This treatment step therefore involves a physical separation of the sediments formed. In order not to introduce confusion with respect to the upstream c) and downstream e) separations, we have not given a specific name to this separation which is therefore an integral part of the processing step d). The final optional separation step e) is necessary in the case where the upstream separation c) has been carried out in a summary manner. The final separation step e) then makes it possible to separate the heavy hydrocarbon fraction with reduced sediment content which can thus constitute a marine fuel within the meaning of IS08217. DETAILED DESCRIPTION OF THE INVENTION Throughout the description, the expression that follows the phrase "included (e) between ... and ..." shall be understood to include the cited termini. The process according to the invention therefore comprises: a step (a) of hydrotreating in a fixed bed, then a step (b) of hydrocracking at least a portion of the heavy fraction resulting from step (a) , taken alone or mixed with other residual or fluxing cuts, in at least one reactor operating in hybrid mode, that is to say operating in a bubbling bed with a supported catalyst associated with a "dispersed" catalyst consisting of particles very fine catalyst constituting a suspension with the hydrocarbon liquid phase to be treated; - a step (c) for separating the effluent from the hydrocracking zone b) making it possible to obtain at least one light fraction and at least one heavy fraction; , d) an optional sediment treatment step for reducing the sediment content of the heavy fraction and obtaining said sediment-reduced liquid hydrocarbon fraction (less than 0.1% by weight). e) an optional step of final separation of the effluent from the treatment step d) to obtain distillates and said sediment-reduced liquid hydrocarbon fraction. The scope of the present invention is defined by the fact that one of the reactors of the hydrocracking zone is of the "hybrid" type, the other reactors of the hydrocracking zone may be of a bubbling type, or hybrid". For simplicity in the rest of the text we will speak of hydrocracking zone mode or bed "hybrid". The objective of step a) of fixed bed hydrotreating is both to refine, that is to say substantially reduce the content of metals, sulfur and other impurities, and to improve the hydrogen ratio on carbon (H / C) of the hydrocarbon feed while transforming said hydrocarbon feed at least partially into lighter cuts. The effluent obtained at the end of the fixed bed hydrotreatment step (a) is then sent without intermediate separation to the hybrid bed hydrocracking step (b) which makes it possible to partially convert the said heavy fraction so as to to produce an effluent that can be used totally or partly as fuel oil or as a fuel oil base, especially as bunker oil or as a bunker oil base. The fact of not performing an intermediate separation between step a) of hydrotreating in a fixed bed and step b) of hydrocracking makes it possible to reduce the costs, in particular the investment costs of the separation equipment, but also the costs. the compression costs due to the implementation of a single loop of hydrogen circulation. One of the interests of the sequence of a hydrotreatment in a fixed bed and then a hydrocracking in a "hybrid" bed lies in the fact that the charge of the hybrid bed hydrocracking reactor is already at least partially hydrotreated. In this way, it is possible to obtain equivalent conversion of hydrocarbon effluents of better quality, in particular with lower sulfur contents. In addition, supported and dispersed catalyst consumption in the hybrid bed hydrocracking step is greatly reduced compared to a process without prior fixed bed hydrotreatment. The hydrocarbonaceous charte The hydrocarbon feedstock treated in the process according to the invention can be described as a heavy load. It has an initial boiling point of at least 350 ° C and a final boiling temperature of at least 450 ° C. Preferably, its initial boiling point is at least 375 ° C., and its final boiling point is at least 460 ° C., preferably at least 500 ° C., and even more preferably at least minus 600 ° C. The hydrocarbon feedstock may be chosen from atmospheric residues (RA) obtained from an atmospheric distillation, vacuum residues (RSV) resulting from vacuum distillation, deasphalted oils, deasphalting resins, asphalts or pitching pitches. deasphalting, residues resulting from conversion processes such as coking, aromatic extracts from lubricant base production lines, oil sands or their derivatives, bituminous shales or their derivatives, parent rock oils or their derivatives , taken alone or mixed. In the present invention, the charges which are treated are preferably atmospheric residues (RA) or vacuum residues (RSV), or residues of conversion processes, or any mixtures of these different types of residues. In addition, the hydrocarbon feedstock treated in the process according to the invention is sulfurized. Its sulfur content is at least 0.5% by weight, preferably at least 1% by weight, more preferably at least 2% by weight.

In addition, the hydrocarbon feedstock treated in the process according to the invention may contain asphaltenes. Its asphaltenes content may be at least 1% by weight, preferably at least 2% by weight. These charges can be used as is or diluted by a co-charge. This co-charge may be a hydrocarbon fraction or a mixture of lighter hydrocarbon fractions, which may preferably be chosen from products derived from a fluid-bed catalytic cracking (FCC) process, a light cutting oil (LCO or "Light cycle oil" according to the English terminology), a heavy cutting oil (HCO or "heavy cycle oil" according to the English terminology), a decanted oil, a residue of FCC, a diesel fraction, 10 including a fraction obtained by atmospheric or vacuum distillation, such as, for example, vacuum gas oil, or possibly from another refining process. The co-charge may also consist of one or more cuts from the process of liquefying coal or biomass, aromatic extracts, or any other hydrocarbon cuts or non-petroleum fillers such as pyrolysis oil. The heavy hydrocarbon feedstock according to the invention may represent at least 50%, preferably 70%, more preferably at least 80%, and even more preferably at least 90% by weight of the total hydrocarbon feedstock treated by the process according to the invention. . Hydrotreating Step (a) The heavy hydrocarbon feedstock is subjected according to the process of the present invention to a fixed bed hydrotreatment step (a) in which the feedstock and hydrogen are contacted on a catalyst. hydrotreating. Hydroprocessing, commonly referred to as HDT, is understood to mean catalytic treatments with a hydrogen supply that makes it possible to refine, that is to say substantially reduce the content of metals, sulfur and other impurities contained in the hydrocarbon feed while increasing the hydrogen-to-carbon ratio of the charge. Hydroprocessing is accompanied by the formation of slices lighter than the feedstock. Hydrotreating includes, in particular, hydrodesulfurization reactions (commonly referred to as HDS), hydrodenitrogenation reactions (commonly referred to as HDN), and hydrodemetallation reactions (commonly referred to as HDM), accompanied by hydrogenation, hydrodeoxygenation, hydrogenation, and hydrogenation reactions. hydrodearomatization, hydro-etherification, hydrodealkylation, hydrocracking, hydro-deasphalting and Conradson carbon reduction. According to a preferred variant, the hydrotreatment stage (a) comprises a hydrodemetallation first stage (a1) (HDM) carried out in one or more hydrodemetallation zones in fixed beds, and a second stage (a2) subsequent to hydrodesulfurization (HDS) carried out in one or more hydrodesulfurization zones in fixed beds. According to one preferred embodiment, the fixed bed hydrotreating zone may comprise permutable reactors, for example reactive guards reactors which allow, in a sequence including steps of operation, shutdown, unloading and replacement of the reactor. catalyst, a longer cycle time, especially for loads with high metal contents. During said first hydrodemetallation step (a1), the feedstock and the hydrogen are contacted on a hydrodemetallization catalyst under hydrodemetallation conditions and then during said second step (a2). hydrodesulfurization, the effluent of the first step (a1) of hydrodemetallation is brought into contact with a hydrodesulphurization catalyst, under hydrodesulfurization conditions. This process, known as HYVAHL-FTM, is for example described in US Patent 5,417,846. Between the hydrodemetallation step and the hydrodesulfurization step, the skilled person sometimes defines a transition zone. Whether during the hydrodemetallization stage, during the transition stage, or during the hydrodesulfurization stage, all types of hydrotreatment reaction occur. However, these appellations come in particular from the fact that the majority of the metals are removed during the hydrodemetallization stage, whereas during the hydrodesulfurization stage, the majority of the reactions taking place are of the hydrodesulfurization type. The hydrotreatment step (a) according to the invention may advantageously be carried out at a temperature of between 300 ° C. and 500 ° C., preferably between 350 ° C. and 420 ° C., and under an absolute pressure of between 2 MPa and 35 MPa, preferably between 11 MPa and 20 MPa. Most often, the space velocity of the hydrocarbon feedstock, commonly referred to as VVH, which is defined as the volumetric flow rate of the feedstock taken at the process conditions divided by the total reactor volume, can be in a range from 0 , 1 h-1 to 5 h -1, preferably from 0.1 h -1 to 2 h -1, and more preferably from 0.1 h -1 to 0.45 h -1. The amount of hydrogen mixed with the feedstock may be between 100 and 5000 normal cubic meters (Nm3) per cubic meter (m3) of liquid feedstock, preferably between 200 Nm3 / m3 and 2000 Nm3 / m3, and more preferably between 300 Nm3 / m3 and 1500 Nm3 / m3. The hydrotreating step (a) can be carried out industrially in one or more liquid downflow reactors. The hydrotreatment catalysts used are generally granular catalysts comprising, on a support, at least one metal or metal compound having a hydrodehydrogenating function. These catalysts may advantageously be catalysts comprising at least one Group VIII metal, generally selected from the group consisting of nickel and cobalt, and / or at least one Group VIB metal, preferably molybdenum and / or tungsten. 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% may be employed. by weight of molybdenum, preferably from 5% to 20% by weight of molybdenum (expressed as molybdenum oxide MoO 3) on a mineral support. This support may for example be chosen from the group consisting of alumina, silica, silica-aluminas, magnesia, clays and mixtures of at least two of these minerals. In the case of a hydrotreatment step including a hydrodemetallation step (HDM) and then a hydrodesulphurization step (HDS), specific catalysts adapted to each step are preferably used. Catalysts which can be used in the HDM step are, for example, indicated in patent documents EP 0113297, EP 0113284, US Pat. No. 5,222,056, US Pat. No. 5,827,421, US Pat. No. 7,110,445, US Pat. No. 5,622,616 and US Pat. No. 5,089,463. HDM catalysts are preferably used. in permutable reactors. Catalysts that can be used in the HDS step are, for example, indicated in patent documents EP 0113297, EP 0113284, US Pat. No. 6589908, US Pat. No. 4,818,743 or US Pat. No. 6,332,976. A mixed catalyst, active in HDM and HDS, can also be used. both for the HDM section and for the HDS section as described in FR 2940143. Prior to the injection of the feedstock, the catalysts used in the process according to the present invention are preferably subjected to in-situ or ex-situ sulphurization. Step b) hydrocracking The effluent obtained at the end of step (a) of hydrotreating in a fixed bed does not undergo any intermediate separation and feeds the hybrid bed hydrocracking section. The hybrid bed hydrocracking section may be divided into three variants: a hydrocracking zone comprising a bubbling bed reactor followed by a hybrid bed reactor; a hydrocracking zone comprising a hybrid bed reactor followed by a hybrid bed reactor, - hydrocracking zone comprising a single hybrid bed reactor. In the variants comprising two reactors, between two hydrocracking reactors, at least one inter-stage separator making it possible to separate a gas fraction and a liquid fraction, can be installed so as to send to the second reactor only the liquid fraction resulting from inter-floor separator. The "disperse" catalyst that occurs in the hybrid bed reactor is a sulfide catalyst preferably containing at least one member selected from the group consisting of Mo, Fe, Ni, W, Co, V, Ru. These catalysts are generally monometallic or bimetallic (by combining, for example, an element of the non-noble MME group (Co, Ni, Fe) and a member of the VIE group (Mo, W) .The catalysts used may be heterogeneous solid powders ( such as natural ores, iron sulphate, etc.), dispersed catalysts derived from water-soluble precursors such as phosphomolybdic acid, ammonium molybdate, or a Mo oxide mixture or Neither with aqueous ammonia The catalysts used are preferably derived from soluble precursors in an organic phase (oil-soluble catalysts) The precursors are organometallic compounds such as the naphthenates of Mo, Co, Fe or Ni, or the Mo octoates, or the multi-carbonyl compounds of these metals, for example 2-ethyl hexanoates of Mo or Ni, acetylacetonates of Mo or Ni, C7-C12 fatty acid salts of Mo or W, etc. They can be used in pre the presence of a surfactant to improve the dispersion of the metals, when the catalyst is bimetallic. The catalysts are in the form of dispersed particles, colloidal or otherwise depending on the nature of the catalyst. Such precursors and catalysts that can be used in the process according to the invention are widely described in the literature. In general, the catalysts are prepared before being injected into the feed. The preparation process is adapted according to the state in which the precursor is and of its nature. In all cases, the precursor is sulfided (ex-situ or in-situ) to form the catalyst dispersed in the feedstock. For the preferred case of so-called oil-soluble catalysts, in a typical process, the precursor is mixed with a carbonaceous feedstock (which may be part of the feedstock to be treated, an external feedstock, a recycled fraction, etc.). the mixture is then sulphurized by addition of a sulfur compound (preferred hydrogen sulphide or optionally an organic sulphide such as DMDS in the presence of hydrogen) and heated. The preparations of these catalysts are described in the literature. The "dispersed" catalyst particles as defined above (powders of metallic mineral compounds or of precursors which are soluble in water or in oil) generally have a size of between 1 nanometer and 150 microns, preferably between 0.1 and 100 microns, and even more preferably between 10 and 80 microns. The content of catalytic compounds (expressed as weight percentage of metal elements of group VIII and / or of group VIB) is between 0 and 10% by weight, preferably between 0 and 1% by weight. Additives may be added during the preparation of the dispersed catalyst or dispersed catalyst before it is injected into the reactor. These additives are described in the literature. The preferred solid additives are inorganic oxides such as alumina, silica, mixed Al / Si oxides, supported spent catalysts (for example, on alumina and / or silica) containing at least one group VIII element (such as that Ni, Co) and / or at least one element of the VIE group (such as Mo, W). For example, the catalysts described in the application US2008 / 177124. Carbonaceous solids with a low hydrogen content (for example 4% hydrogen), such as coke or ground activated carbon, optionally pretreated, can also be used. Mixtures of such additives can also be used. The particle size of the additive is generally between 10 and 750 microns, preferably between 100 and 600 microns. The content of any solid additive present at the inlet of the hydrocracking reaction zone in a hybrid bed is between 0 and 10 wt.%, Preferably between 1 and 3 wt.%, And the content of catalytic compounds (expressed as a percentage wt. metal elements of group VIII and / or of the group VIS) is between 0 and 10% by weight, preferably between 0 and 1% by weight.

The hybrid bed reactor (s) used in the hydrocracking zone therefore consist of two populations of catalysts, a first population using supported catalysts in the form of extrudates whose diameter is advantageously between 0.8 and 1.2 mm. , generally equal to 0.9 mm or 1.1 mm and a second population of "dispersed" type catalyst discussed above.

The fluidization of the catalyst particles in the bubbling bed is enabled by the use of a boiling pump which allows a recycle of liquid, generally inside the reactor. The flow rate of liquid recycled by the boiling pump is adjusted so that the catalyst particles are fluidized but not transported, so that these particles remain in the bubbling bed reactor (with the exception of catalysts that can be formed by attrition and entrained with the liquid since these fines are small). For the bubbling bed reactor, use may be made of a conventional granular hydrocracking catalyst, generally an extrudate, comprising, on an amorphous support, at least one metal or metal compound having a hydro-dehydrogenating function.

This catalyst may be a catalyst comprising Group VIII metals, for example nickel and / or cobalt, most often in combination with at least one Group VIB metal, for example molybdenum and / or tungsten. For example, a catalyst comprising from 0.5% to 10% by weight of nickel and preferably from 1% to 5% by weight of nickel (expressed as nickel oxide NiO) and from 1% to 30% by weight may be used. molybdenum, preferably from 5% to 20% by weight of molybdenum (expressed as molybdenum oxide MoO 3) on an amorphous mineral support. This support may for example be chosen from the group consisting of alumina, silica, silica-aluminas, magnesia, clays and mixtures of at least two of these minerals. This support may also contain other compounds and for example oxides selected from the group consisting of boron oxide, zirconia, titanium oxide, phosphoric anhydride. Most often an alumina support is used and very often a support of alumina doped with phosphorus and possibly boron.

When phosphorus pentoxide P205 is present, its concentration is usually less than 20% by weight and most often less than 10% by weight. When B203 boron trioxide is present, its concentration is usually less than 10% by weight. The alumina used is usually y (gamma) or hal (eta) alumina. This catalyst may be in the form of extrudates. The total content of metal oxides of groups VI and VIII may be between 5% and 40% by weight, preferably between 7% and 30% by weight, and the weight ratio expressed as metal oxide between metal (or metals) of group VI on metal (or metals) of group VIII is between 20 and 1, preferably between 10 and 2. The used catalyst can be partly replaced by fresh catalyst, generally by withdrawal at the bottom of the reactor and introduction at the top of the fresh or new catalyst reactor at regular time interval, that is to say for example by puff or continuously or almost continuously. The catalyst can also be introduced from below and withdrawn from the top of the reactor. For example, fresh catalyst can be introduced every day. The replacement rate of spent catalyst with fresh catalyst may be, for example, from about 0.05 kilograms to about 10 kilograms per cubic meter of charge. This withdrawal and this replacement are performed using devices allowing the continuous operation of this hydrocracking step. The hydrocracking reactor usually comprises a recirculation pump for maintaining the catalyst in a bubbling bed by continuous recycling of at least a portion of the liquid withdrawn at the top of the reactor and reinjected at the bottom of the reactor. It is also possible to send the spent catalyst withdrawn from the reactor into a regeneration zone in which the carbon and the sulfur contained therein are eliminated before it is reinjected in the hydrocracking step b). For a reactor operating in a bubbling bed during step b) of hydrocracking, its implementation can be similar to that of the H-OIL® process as described for example in US Pat. No. 6,270,654. Whatever the configuration of the hydrocracking zone, the operating conditions of the hydrocracking zone are in general the following: a pressure of 2 to 35 MPa, preferably 10 to 25 MPa, a hydrogen partial pressure ranging from 2 to 35 MPa and preferably from 10 to 30 MPa, a temperature of between 330 ° C. and 550 ° C., preferably from 350 ° C. to 500 ° C., and still more preferably between 370 ° C. and 480 ° C., a reactor hourly space velocity. (VVH reactor, ie ratio between the flow rate of charge and the reactor volume) of between 0.1 and 10 h -1, preferably of 0.1 h to 5 h 1 and more preferably between 0.1 and 2 h-1, - hourly space velocity "bubbling bed catalysts" for bed reactors Ionic or hybrid (VVH "bubbling bed catalysts", ie the ratio between the flow rate of charge in Sm3 / h and the volume in m3 of bubbling bed catalysts at rest, when the expansion rate of the ebullating bed is zero) between 0.1 and 5 h -1, preferably from 0.1 h to 3 h -1 and more preferably between 0.1 and 1 h -1, a content of catalytic compounds in the "dispersed" catalysts for hybrid bed reactors (expressed as a percentage by weight of metal elements of group VIII and / or of the group VIE) of between 0 and 10% by weight, preferably between 0 and 1% by weight, a hydrogen / charge ratio of between 50 and 5000 Nm3 / m3, most often from about 100 to about 1500 Nm3 / m3, with a preferred range between 500 and 1300 Nm3 / m3. The operating conditions of the hydrocracking zone in at least one reactor containing a "dispersed" catalyst coupled with the fact that the feedstock was previously hydrotreated in step a) of hydrotreatment, make it possible to obtain conversion rates ranging from between 30 and 100%, preferably between 40 and 80% and hydrodesulphurization rates between 70 and 100%, preferably between 85 and 99%. The conversion rate mentioned above is defined as the amount of compounds having a boiling point above 520 ° C in the initial hydrocarbon feed, minus the amount of compounds having a boiling point above 520 ° C. in the hydrocarbon effluent obtained at the end of the hydrocracking step b), all divided by the amount of compounds having a boiling point greater than 520 ° C. in the initial hydrocarbon feedstock. A high conversion rate is advantageous to the extent that this conversion rate illustrates the production of conversion products, mainly atmospheric distillates and / or vacuum distillates of the naphtha, kerosene and diesel type, in a significant amount. The hydrodesulphurization rate mentioned above is defined as the amount of sulfur in the initial hydrocarbon feed, minus the amount of sulfur in the hydrocarbon effluent obtained at the end of the hydrocracking step b). all divided by the amount of sulfur in the initial hydrocarbon feed. Step c) of separating the hydrocracking effluent The process according to the invention comprises a step c) of separation make it possible to obtain at least one gaseous fraction and at least one liquid hydrocarbon fraction. The effluent obtained at the end of the hydrocracking step b) comprises a liquid fraction and a gaseous fraction containing the gases, in particular H 2, H 2 S, NH 3, and C 1 -C 4 hydrocarbons. This gaseous fraction can be separated from the hydrocarbon effluent by means of separating devices well known to those skilled in the art, in particular by means of one or more separator flasks that can operate at different pressures and temperatures, possibly associated with each other. steam or hydrogen stripping means, and generally one or more distillation columns. The effluent obtained at the end of the hydrocracking step b) is advantageously separated in at least one separator flask into at least one gaseous fraction and at least one liquid fraction. These separators may, for example, be high temperature high pressure separators (HPHT) and / or low temperature high pressure separators (HPBT). After possible cooling, this gaseous fraction is preferably treated in a hydrogen purification means so as to recover the hydrogen that is not consumed during the hydrotreatment and hydrocracking reactions. The hydrogen purification means may be an amine wash, a membrane, a PSA (pressure swing adsorption) system, or a plurality of these means arranged in series. The purified hydrogen can then advantageously be recycled in the process according to the invention, after possible recompression. The hydrogen may be introduced at the inlet of the hydrotreatment step (a) and / or at different locations during the hydrotreatment step (a) and / or at the inlet of the (b) step. hydrocracking and / or at different locations during step b) hydrocracking. The separation step c) may also comprise a steam or hydrogen stripping step, generally steam, in order to remove at least one gas fraction rich in hydrogen sulfide (H2S). The separation step c) may also comprise atmospheric distillation and / or vacuum distillation. Advantageously, the separation step (c) further comprises at least one atmospheric distillation, in which the liquid hydrocarbon fraction (s) obtained (s) after separation is (are) fractionated (s) by atmospheric distillation into at least one atmospheric distillate fraction and at least one atmospheric residue fraction. The atmospheric distillate fraction may contain commercially recoverable fuels bases (naphtha, kerosene and / or diesel), for example in the refinery for the production of motor and aviation fuels. In addition, the separation step (c) of the process according to the invention may advantageously also comprise at least one vacuum distillation in which the liquid hydrocarbon fraction (s) obtained (s) after separation and / or the atmospheric residue fraction obtained after atmospheric distillation is (are) fractionated by vacuum distillation into at least one vacuum distillate fraction and at least one vacuum residue fraction. Step c) of separation of the effluent from the hydrocracking step can be carried out either in a summary manner, allowing the production of one or two liquid fractions, or in a more complete manner and allowing the production of at least three liquid fractions. The more complete separation c) 15 thus makes it possible to obtain well-separated atmospheric and / or vacuum distillate cuts (naphtha, kerosene, gas oil, vacuum gas oil, for example) from the atmospheric residue and / or under vacuum. The manner in which this separation step is performed conditions the sequence of optional steps d) and e). According to a first embodiment corresponding to a rather complete separation, the separation step (c) comprises a hot high pressure flask, a high pressure cold flask, a low pressure hot flask, a low pressure cold flask, and then a liquid fraction from separator flasks, an atmospheric distillation, wherein the liquid hydrocarbon fraction (s) obtained after separation is (are) fractionated by atmospheric distillation in at least one atmospheric distillate fraction and at least one atmospheric residue fraction, followed by vacuum distillation in which the atmospheric residue fraction obtained after atmospheric distillation is fractionated by vacuum distillation into at least one vacuum distillate fraction and at least one vacuum residue fraction. The vacuum distillate fraction typically contains vacuum gas oil fractions. At least a portion of the atmospheric residue fraction and / or the vacuum distillate fraction, and / or the vacuum residue fraction, may be recycled to the hydrocracking step b) or step a) hydrotreatment or be sent to product tanks or be treated in another refining unit (catalytic cracking or vacuum distillate hydrocracking, for example). According to a second embodiment corresponding to a summary separation, the separation step (c) comprises a hot high pressure flask, a high pressure cold flask, a low pressure hot flask, a low pressure cold flask and then a liquid fraction. from the separator flasks, a steam stripping column for removing at least one light fraction rich in hydrogen sulfide. This second embodiment may be advantageous during the implementation of the optional steps d) of treatment of sediments and catalyst residues and e) separation of the liquid fraction from step c).

Thus, the distillation columns of step e) are less prone to fouling since they treat a liquid fraction whose sediment content was reduced during step d). It is therefore advantageous to carry out step c) in a summary manner by using a minimum of equipment that processes a hydrocarbon fraction that may contain sediments.

At the end of the separation step (c), at least one liquid hydrocarbon fraction having a sulfur content of less than or equal to 0.5% by weight, preferably less than or equal to 0.3% by weight, is obtained. and more preferably less than or equal to 0.1% by weight. This liquid hydrocarbon fraction can advantageously be used as a base of fuel oil or as fuel oil, especially as a base of bunker oil or as fuel oil, with low sulfur content meeting the new recommendations of the International Maritime Organization. Advantageously, all of the liquid hydrocarbon effluent obtained at the end of the separation step (c) may have a sulfur content of less than or equal to 0.5% by weight, and preferably less than or equal to 0.3. % in weight.

This liquid hydrocarbon effluent may, at least in part, advantageously be used as fuel oil bases or as fuel oil, especially as a base of bunker oil or as fuel oil, with low sulfur content meeting the new recommendations of the International Maritime Organization . By "fuel" is meant in the invention a hydrocarbon feedstock useful as a fuel. By "oil base" is meant in the invention a hydrocarbon feed which, mixed with other bases, constitutes a fuel oil. Depending on the origin of these bases, in particular depending on the type of crude oil and the type of refining, the properties of these bases, in particular their sulfur content and their viscosity, are very diverse. One of the interests of the sequence of a hydrotreatment in a fixed bed and then a hydrocracking in at least one reactor containing a "dispersed" catalyst lies in the fact that the charge of the hybrid bed hydrocracking reactor is already at less partially hydrotreated. In this way, it is possible to obtain equivalent conversion of hydrocarbon effluents of better quality, in particular with lower sulfur contents. In addition, supported and dispersed catalyst consumption in the hybrid bed hydrocracking step is greatly reduced compared to a process without prior fixed bed hydrotreating. Optional step d) of sediment treatment The hydrocarbon effluent obtained at the end of step c) of separation of the hydrocracking effluent, and in particular the heavier liquid fraction obtained, generally a fraction of residual type atmospheric or vacuum residue, may contain sediments and catalyst residues. At least a portion of the sediments may consist of precipitated asphaltenes resulting from a hydrocracking of a petroleum residue feed. The catalyst residues may be fines resulting from the attrition of extruded type catalysts in the implementation of bubbling bed hydrocracking reactor. The phenomenon of attrition of extruded type catalysts can also be in a hybrid bed. Another part of the catalyst residues comes from the "dispersed" catalyst. In order to obtain a fuel oil or a fuel base which meets the recommendations of a sediment content after aging (IP390) less than or equal to 0.1%, the process according to the invention may comprise an additional step of separating the sediments and catalyst residues of the liquid hydrocarbon effluent after the separation step c). Depending on the hydrocracking conditions, the sediment content in the heavy fraction varies. From an analytical point of view, existing sediments (IP375) and sediments after aging (IP390) are distinguished from potential sediments. Depending on the hydrocracking conditions, it may therefore be necessary to carry out, during the sediment treatment stage e), a maturation stage upstream of the solid-liquid separation techniques mentioned above. This maturation step converts potential sediments into existing sediments so that all existing sediments after treatment can be separated more efficiently and thus meet the sediment content after aging (IP390) of 0.1%. max. The maturation step consists in applying a residence time of between 1 and 1500 minutes, preferably between 30 and 300 minutes, more preferably between 60 and 180 minutes, with the heavy fraction previously heated to a temperature between 100 and 500 minutes. ° C, preferably between 150 and 350 ° C, and more preferably between 200 and 300 ° C. The pressure of the maturation stage is less than 200 bar, preferably less than 100 bar, more preferably less than 30 bar, and even more preferably less than 10 bar. This maturation step can be done, for example with an exchanger or a heating furnace and then one or more capacity (s) in series or in parallel such (s) as a horizontal or vertical balloon, optionally with a decanting function for remove some of the heavier solids, and / or a piston reactor. A stirred and heated tank may also be used, and may optionally be bottom tapped to remove some of the heavier solids. Optionally, the maturation step can be carried out in the presence of an inert gas (nitrogen for example) or oxidizing (oxygen, air or air depleted by nitrogen). The use of an oxidizing gas accelerates the maturation process. According to this option, there is therefore introduction of a gas in mixture with the liquid fraction resulting from stage c) before maturation, then separation of this gas after maturation so as to obtain a liquid fraction at the outlet of the maturation stage and send it to the stage of physical separation of sediments. One of the challenges of using "disperse" catalysts in hydrocracking processes is the cost of this "dispersed" catalyst. The present invention limits the cost of hydrocracking catalysts due to the upstream hydrotreating step. It may, however, be advantageous to at least partially recover the "dispersed" catalyst present in the heavy cuts. This step of recovering the "disperse" catalyst can therefore be carried out consecutively, or simultaneously with the step of separating the sediments and the catalyst residues. The method according to the invention may therefore further comprise a treatment step d) allowing the separation of sediments and catalyst residues, optionally coupled simultaneously or consecutively, to a "dispersed" catalyst recovery step.

During this step d), at least a portion of the atmospheric residue and / or vacuum residue fractions are separated from the sediments and catalyst residues, optionally coupled simultaneously or consecutively, to a catalyst recovery step " dispersed ", using in step d), after the maturation for converting the potential sediments into existing sediments, at least one filter, a separation on membranes, a bed of organic or inorganic type filtering solids, an electrostatic precipitation , a centrifuge system, in-line decantation, auger withdrawal. Step d) of sediment treatment is therefore a clever coupling of a first stage of maturation for converting the potential sediments into existing sediments and then a second step of solid-liquid physical separation making it possible to remove at least part of the sediment. all existing sediments. At the end of step d) of sediment treatment, at least one liquid hydrocarbon fraction having a sulfur content of less than or equal to 0.5% by weight, preferably less than or equal to 0.3% by weight, is obtained. weight, and more preferably less than or equal to 0.1% by weight. In addition, the liquid hydrocarbon fraction resulting from step d) of sediment treatment is characterized by a sediment content after aging (IP390) of less than 0.1% by weight. This liquid hydrocarbon fraction may advantageously be used as a base for fuel oil or as fuel oil, especially as a bunker oil or bunker oil base, with a low sulfur content and with a low sediment content after aging in accordance with the new recommendations of the Organization. International Maritime and IS08217 standard for marine fuels. Advantageously, all of the liquid hydrocarbon effluent obtained at the end of step d) of treatment of the sediments has a sulfur content less than or equal to 0.5% by weight, and preferably less than or equal to 0, 3% by weight. Advantageously, all of the liquid hydrocarbon effluent obtained at the end of step d) of sediment treatment has a sediment content after aging (IP390) of less than 0.1% by weight. Optional Step e) Separating the effluent from the sediment treatment step The method according to the invention comprises a step e) of separation make it possible to obtain at least one liquid hydrocarbon fraction. The effluent obtained at the end of the sediment treatment step d) comprises at least one liquid fraction. The composition of this liquid fraction depends on the manner in which step c) of separation of the hydrocracking effluent has been carried out. If step c) was carried out in a summary manner, the effluent resulting from step c) thus contains a mixture of distillates and residues that must be separated in order to valorize each of the cuts, by putting at least one distillation column. If step c) was conducted more completely, only a liquid fraction of the vacuum residue type and / or atmospheric residue was sent to the sediment treatment step d). In the case of a more complete separation c), the liquid fraction resulting from step d) may therefore not require optional step e). We will not take over all separation equipment that can be implemented 15 during the step e) of separation since they are well known to those skilled in the art and already mentioned during the steps c) of separation ( separating flasks, columns, etc.) At the end of the separation step (e), at least one liquid hydrocarbon fraction having a sulfur content of less than or equal to 0.5% by weight, preferably less than or equal to equal to 0.3% by weight, and more preferably less than or equal to 0.1% by weight. In addition, the liquid hydrocarbon fraction from the separation step e) is characterized by a sediment content after aging (IP390) of less than 0.1% by weight. This liquid hydrocarbon fraction can advantageously be used as a base of fuel oil or as fuel oil, especially as a base of bunker oil or as fuel oil, with low sulfur content and low sediment content after aging in accordance with the new recommendations of the Organization. International Maritime and IS08217 standard for marine fuels. By "fuel" is meant in the invention a hydrocarbon feedstock used as fuel. By "oil base" is meant in the invention a hydrocarbon feed which, when mixed with other bases, constitutes a fuel oil. Depending on the origin of these bases, in particular depending on the type of crude oil and the type of refining, the properties of these bases, in particular their sulfur content and their viscosity, are very diverse.

DETAILED DESCRIPTION OF FIG. 1 FIG. 1 represents a process according to the invention without intermediate separation. The introduction of the feedstock (10) to the outlet of the effluent (42) represents the hydrotreatment zone and this zone is described briefly because it can know many variants known to those skilled in the art. In FIG. 1, the charge (10), preheated in the enclosure (12), mixed with recycled hydrogen (14) and additional hydrogen (24) preheated in the enclosure (16) , is introduced via the pipe (18) into the guard zone represented by the two reactors Ra and Rb. These reactors are generally reactive reactors in the sense that they operate according to a series of cycles each comprising four successive stages: a first step (step i) during which the charge passes successively through the reactor Ra and then the reactor Rb; a second step (step ii) in which the charge passes only through the reactor Rb, the reactor Ra being short-circuited for regeneration and / or replacement of the catalyst, - a third step (step iii) during which the load passes through successively the reactor Rb, then the reactor Ra, 20 - a fourth step (step iv) during which the feed passes only through the reactor Ra, the reactor Rb being short-circuited for regeneration and / or replacement of the catalyst. The cycle can then start again. Returning to FIG. 1, the effluent exiting the at least one guard reactor (Ra, Rb) is optionally remixed with hydrogen arriving via line (65) into an HDM reactor (32) which encloses a bed fixed catalyst. For readability reasons, a single HDM reactor (32) and a single HDS reactor (38) are shown in the figure, but the HDM and HDS section may include multiple HDM and HDM reactors. 'HDS in series. The effluent from the HDM reactor is withdrawn through line (34) and sent to the first HDS reactor (38) where it passes through a fixed bed of catalyst. The effluent from the hydrotreatment stage is sent via line (42) into an exchanger (43) for adjusting the temperature and thus controlling the temperature at the inlet of the furnace (92). Optionally, a co-charge (94) may be introduced.

The stream (44) is mixed with recycled hydrogen (88) optionally supplemented with makeup hydrogen (90) preheated in the furnace (91). It optionally passes through an oven (92). The heavy fraction is then introduced via line (96) into the hydrocracking step at the bottom of the first hybrid bed reactor (98) operating at an upward flow of liquid and gas and containing at least one type hydrocracking catalyst. "Dispersed" and a supported catalyst. Recall that in the context of the present invention, a hybrid bed is a bubbling bed which contains a supported catalyst which has been added a "dispersed" catalyst.

The "dispersed" type catalyst is introduced via line (100) upstream of the first hydrocracking reactor (98). Optionally, the converted effluent (104) from the reactor (98) may be separated from the light fraction (106) in an inter-stage separator (108). All or part of the effluent (110) from the inter-stage separator (108) is advantageously mixed with additional hydrogen (157), if necessary preheated (not shown). This mixture is then injected by the pipe (112) into a second hydrocracking reactor (102) also in a hybrid bed operating at an upward flow of liquid and gas containing at least one "dispersed" hydrocracking catalyst and a catalyst. 20 supported. This "dispersed" type catalyst was injected upstream of the first reactor (98), but a booster upstream of the second reactor (102) could also be achieved via a conduit not shown. The operating conditions, especially the temperature, in this reactor are chosen to reach the desired conversion level, as previously described. The hydrocracking reactor effluent is fed through line (134) into a high temperature high pressure (HPHT) separator (136) from which a gaseous fraction (138) and a liquid fraction (140) are recovered. The gaseous fraction (138) is sent generally via an exchanger (not shown) or an air cooler (142) for cooling to a low temperature high pressure separator (HPBT) (144) from which a gaseous fraction (146) containing gases (H2, H2S, NH3, C1-C4 hydrocarbons ...) and a liquid fraction (148).

The gaseous fraction (146) of the low temperature high pressure separator (HPBT) (144) is treated in the hydrogen purification unit (150) from which hydrogen (152) is recovered for recycling via the compressor. (154) and line (156) and / or line (157) to the hydrocracking section.

The hydrogen purification unit may consist of an amine wash, a membrane, a PSA type system. The gases containing undesirable nitrogen and sulfur compounds are removed from the installation (stream (158) which may represent several streams, in particular a flow rich in H2S and one or more purges containing light hydrocarbons (Cl and C2) which can (can ) be used in refinery fuel gas). The liquid fraction (148) of the low temperature high pressure separator (HPBT) (144) is expanded in the device (160) and sent to the fractionation system (172). Optionally, a medium pressure separator (not shown) after the expander (160) can be installed to recover a vapor phase that is sent to the purification unit (150) and / or a dedicated medium pressure purification unit (no shown), and a liquid phase which is fed to the fractionation section (172). The liquid fraction (140) from the high temperature high pressure separation (HPHT) (136) is expanded in the device (174) and sent to the fractionation system (172). Optionally, a medium pressure separator (not shown) after the expander (174) can be installed to recover a vapor phase that is sent to the purification unit (150) and / or a dedicated medium pressure purification unit (no shown), and a liquid phase which is fed to the fractionation section (172). Of course, the fractions (148) and (140) can be sent together, after expansion, to the system (172). The fractionation system (172) comprises an atmospheric distillation system for producing a gaseous effluent (176), at least a so-called light fraction (178), containing in particular naphtha, kerosene and diesel, and an atmospheric residue ( 180). Part of the atmospheric residue fraction (180) can be withdrawn via line (182) to form a desired fuel oil base. All or part of the atmospheric residue fraction (180) can be sent to a vacuum distillation column (184) to recover a fraction containing the vacuum residue (186) and a vacuum distillate fraction (188) containing gas oil under empty. Optionally, the atmospheric residue fraction (182) and / or the vacuum residue fraction (186) may be subjected to a step of treatment and separation of sediments and catalyst residues. A heavy fraction of the atmospheric residue type (182) is optionally preheated in an oven or exchanger (205) so as to reach the temperature necessary for the maturation (conversion of the potential sediments into existing sediments) which takes place in the capacity (207). ). The purpose of the capacity (207) is to provide a residence time necessary for maturation, it can therefore be a horizontal or vertical flask, a buffer tank, a stirred tank or a reactor piston. The heating function can be integrated with the capacity in the case of a stirred stirred tank according to an embodiment not shown. The capacity (207) may also allow settling so as to evacuate a portion of the solids (208). The maturing stream (209) is then subjected to solid-liquid separation (191) to obtain a sediment-reduced fraction (212) and a sediment-rich fraction (211). Similarly, a vacuum residue heavy fraction (186) is optionally preheated in an oven or exchanger (213) so as to reach the temperature necessary for the maturation which takes place in the capacity (215). The purpose of the capacity (215) is to provide a residence time necessary for maturation, it can therefore be a horizontal or vertical flask, a buffer tank, a stirred tank or a reactor piston. The heating function can be integrated with the capacity in the case of a heated stirred tank according to a not shown embodiment. The capacity (215) may also allow settling so as to evacuate a portion of the solids (216). The maturation stream (217) is then subjected to a solid-liquid separation (192) to obtain a sediment-reduced fraction (219) and a sediment-rich fraction (218). According to a mode not shown, the maturation devices (207) and (215) can operate in the presence of a gas, in particular an oxidizing gas. According to a mode not shown, it is also possible to perform a step of treatment and separation of sediments and catalyst residues on a heavy fraction from the effluent separation step, for example on a heavy cut out of a separator, for example on the flow (140) before or after the expansion (174). An advantageous mode not shown may consist in operating the sediment treatment and separation step on the stream recovered at the bottom of a stripping column. When the step of treatment and separation of sediments and catalyst residues is operated upstream of a distillation column, this column is less prone to fouling. At least a portion of the streams (188) and / or (212) and / or (219) constitutes one or more desired oil bases, in particular bases for low-sulfur bunker fuels. Some of the streams (188) and / or (212) and / or (219), before or after the optional sediment treatment and separation step, may be recycled via line (190) to step hydrocracking, or upstream of the hydrotreating step (line not shown). The recycling of a vacuum-type gas oil section (188) upstream of the hydrotreatment can make it possible to lower the viscosity of the charge and thus facilitate pumping. Recycling an atmospheric residue (212) or vacuum residue type (219) cutoff upstream of the hydrotreatment or hydrocracking can increase the overall conversion. The variations of the invention include, in particular for the hydrocracking section instead of the two reactors in a hybrid bed (98) and (102): a bubbling-bed hydrocracking reactor followed by a reactor of hybrid bed hydrocracking - a hybrid bed type hydrocracking reactor followed by a hybrid bed type hydrocracking reactor a hybrid bed type hydrocracking reactor alone. In the variants relating to the type of hydrocracking reactor described above, it is also possible to intercalate an inter-stage separator allowing the elimination of at least one gas fraction between two hydrocracking reactors. COMPARATIVE EXAMPLE ACCORDING TO THE PRIOR ART AND ACCORDING TO THE INVENTION The following example illustrates the invention without, however, limiting its scope. A vacuum residue (RSV Safaniya) containing 88.6% by weight of compounds boiling at a temperature above 520 ° C was treated, having a density at 15 ° C of 1.063 and a sulfur content of 5.62%. in weight. The feedstock was subjected to a fixed bed hydrotreating step a) including two permutable reactors. The operating conditions are given in Table 1.

HDM and HDS NiCoMo catalysts on alumina Temperature (° C) 370 H2 partial pressure (MPa) 15 VVH (h-1, Sm3 / h fresh load / m3 of fixed bed catalyst) 0.12 H2 / HC fixed bed section entrance excluding consumption H2 (Nm3 / m3 fresh feed) 1000 Table 1: Operating conditions of stage a) of hydrotreatment in fixed bed The effluent of the hydrotreatment is then treated according to two schemes: a) in a hydrocracking step b ) comprising two successive bubbling bed reactors (non-compliant, according to the prior art). b) in a hydrocracking step b) comprising two successive bubbling bed reactors with addition of a dispersed catalyst operating in a "hybrid" mode (in accordance with the invention).

The operating conditions of the hydrocracking step b) are given in Table 2. (Non-Compliant) (Compliant) 2 beds 2 hybrid bubbling ebullated beds NiMo catalysts on NiMo on alumina alumina + Naphthalate Mo Temperature R1 (° C) 423 423 Temperature R2 (° C) 431 431 Partial pressure H2 (MPa) 13.5 13.5 VVH "reactors" (h-1, Sm3 / h charge 0.3 0.3 fresh / m3 of reactors) VVH "catalysts bubbling bed "(h-1, Sm3 / h fresh load / m3 of bubbling bed catalysts) 0.6 0.6 Catalyst concentration 100" dispersed "(ppm of precursor in feed input" hybrid "beds) H2 / HC inlet section 1000 1000 hydrocracking excluding consumption H2 (Nm3 / m3 fresh feed) Table 2: Operational conditions of the hydrocracking section b) in both schemes (a) two bubbling beds, (a) two hybrid bubbling beds Effluents hydrocracking step were then subjected to a separation step c) to separate the gases and liquids by means of separators and atmospheric and vacuum distillation columns. In addition, prior to the vacuum distillation step, the atmospheric residue fraction undergoes treatment according to 2 variants: a step of separation of the sediments and catalyst residues comprising a metallic porous filter of brand Pan® (according to the prior art a step of treatment of the sediments and catalyst residues comprising a maturation step (4 h at 150 ° C. carried out in a stirred tank heated in the presence of a 50/50 air / nitrogen mixture under a total pressure of 0.5 MPa) ) and physical separation of the sediments and catalyst residues comprising a filter (in accordance with the invention) The yields and the sulfur contents of each fraction obtained in the effluents leaving the overall chains are given in Table 3 below: (Not compliant) (Complies) (a) Hydrotreating bed a) Hydrotreatment fixed bed + b) fixed + b) Hydrocracking 2 hydrocracking beds 2 bubbling bubbling beds (423/431 ° C) hybrids (423 / 431 ° C) Products Yield S (% wt) Yield S (% wt) (% wt) (wt%) NH3 0.5 0.5 H2S 5.3 94.12 4.5 94.12 C1-C4 (gas) ) 5.8 5.9 Naphtha (PI - 150 ° C) 11.1 0.003 11.5 0.003 Diesel (150 ° C - 350 ° C) 28.7 0.019 28.9 0.019 Vacuum distillate 29.1 0.27 29.5 0.28 (350 ° C - 520 ° C) Vacuum Residue 22.8 0.56 21.6 0.55 (520 ° C +) Table 3: Yields and Sulfur Content of the Section Effluent hydrocracking (% w / w) It is possible to calculate the conversion rates (difference between the amount of components boiling above 520 ° C in the feed and that in the effluent, divided by that of the feed) and the rate of hydrodesulfurization (difference between the amount of sulfur in the feedstock and that in the liquid effluent, divided by that of the feedstock). Finally, the operating conditions of the hydrocracking step coupled with the different treatment variants (sediment separation with or without treatment) of the heavy phase resulting from the atmospheric distillation have an impact on the stability of the effluents obtained. This is illustrated by the post-aging sediment concentrations measured in the atmospheric residues (350 ° C + cut) after separation or after the sediment treatment step.

The performances of the three treatment schemes are summarized in table 4 below: (Non compliant) Hydrotreatment fixed bed + Hydrocracking 2 bubbling beds (423/431 ° C) (Complies) Hydrotreatment fixed bed + Hydrocracking 2 hybrid bubbling beds (423/431 ° C) / 431 ° C) H2 consumption 3.2 3.2 (% w / w) Hydrodesulfurization rate (%) 95.9 95.9 Conversion rate (%) 74 76 Treatment No No Yes Sediment separation Yes Yes Yes Sediment content after aging (1P390) in the 350 ° C + cup resulting from the separation of the sediments 0.5 0.6 <0.1 Table 4: Summary of the performances according to the prior art and according to the invention The results show the significant gain obtained in conversion in the case of the two schemes according to the invention (2 hybrid bubbling beds). These particularly high conversion rates illustrate the production of conversion products (mainly distillates) in a significant amount.

The sediment treatment step e) involving maturation prior to the physical separation of the sediments is essential to form all potential sediments and thus allow their effective separation. Without treatment, beyond a certain conversion level that leads to a lot of potential sediment, the sediment separation step is not efficient enough for the sediment content after aging (1P390) to be less than 0.1% by weight, which is the maximum level required for residual type bunkers. On the other hand, in the case of a less noble application (fuel oil for producing refinery utilities for example), the sediment treatment step e) may be optional, the sediment content will then be greater than 0.1% by weight. . Subsequently, a mixture is prepared from sections 350 ° C-520 ° C and 520 ° C + from the sequence a) hydrotreatment in fixed bed + b) hydrocracking with 2 hybrid bubbling beds + c) separation of the effluent + d) treatment of sediments from the heavy cut, in the following proportions: cut 150 ° C-350 ° C: 2.5% by weight of the mixture, and cut 350 ° C-520 ° C: 42.5% by weight of the mixture, and cut 520 ° C +: 55% by weight of the mixture. There was thus obtained a fuel oil having a sulfur content of 0.42% by weight, and having a viscosity of 378 cSt at 50 ° C. In addition, its sediment content after aging is less than 0.1% by weight. In view of these analyzes, this fuel oil is particularly suitable for forming a residual type of fuel oil related to the RMG 380 grade as recommended by the IMO outside the ZESCs by 2020-2025. In addition to the first mixture leading to a 0.42% sulfur fuel oil, a second mixture consisting of 80% by weight of a fraction obtained from the diesel cut and 20% by weight of a fraction produced by of the vacuum distillate cut. In these proportions, the mixture has a sulfur content of 0.07% and a viscosity of 4 cSt at 40 ° C. This mixture thus constitutes a marine fuel of the distillate type ("marine gas oil" or "marine diesel" in the English terminology) which can be likened to the DMB grade (whose viscosity specification is between 2 cSt and 11 cSt at 40 ° C) for example.

Due to its sulfur content of less than 0.1%, this mixture is a fuel of choice for ZCESs by 2015. 30

Claims (8)

CLAIMS 1-Process for the treatment of a heavy hydrocarbon feedstock having a sulfur content of at least 0.5% by weight, an initial boiling point of at least 350 ° C. and a final boiling point of from 0.degree. at least 450 ° C in order to obtain heavy fuel type fuels, which may possibly become a marine fuel, making it possible to obtain at least one liquid hydrocarbon fraction having a sulfur content of less than or equal to 0.5% by weight, comprising the following successive stages: a) a fixed bed hydrotreatment stage, in which the hydrocarbon feedstock and hydrogen are contacted on a hydrotreatment catalyst, b) a step of hydrocracking the effluent obtained at the end of step (a) of hydrotreating, taken alone or mixed with other residual or fluxing cuts, in at least one reactor operating in hybrid mode, that is to say operating in a bubbling bed with a support catalyst associated with a "dispersed" catalyst consisting of very fine catalyst particles constituting a suspension with the hydrocarbon liquid phase to be treated, c) a step of separating the effluent from step (b) to obtain at least a fraction light and at least one heavy fraction; d) an optional sediment treatment step for reducing the sediment content of the heavy fraction from the separation step c); e) an optional final separation step of the effluent from the treatment step d) to obtain said sediment-reduced liquid hydrocarbon fraction (i.e., less than 0.1% by weight). 25 2-Process for treating a heavy hydrocarbon feedstock according to claim 1, wherein the hydrocracking step is carried out with the following operating conditions: a hydrogen partial pressure ranging from 2 to 35 MPa, and preferably from 10 to 25 MPa, a temperature between 330 ° C and 550 ° C, preferably 350 ° C to 500 ° C, even more preferably between 370 ° C and 480 ° C, - a space velocity hourly (VVH reactor, or ratio between the charge volume flow rate and the reactor volume) between 0.1 and 10 h -1, preferably from 0.1 h to 5 h -1, and more preferably between 0.1 and 2 h -1, a hourly space velocity "bubbling bed catalysts" for bubbling or hybrid bed reactors between 0.1 and 5 h -1, preferably from 0.1 h to 3 h -1 and more preferably between 0.1 and 1 h-1, the VVH "bubbling bed catalyst being defined as the ratio between the flow rate of charge in m 3 / h and the volume in m3 of bubbling bed catalyst at rest, that is to say when the expansion rate of the bubbling bed is zero, - a content of metal compounds in the catalysts used in a hybrid bed of between 0 and 10 % wt, preferably between 0 and 1 wt.%, said content being expressed as a weight percentage of metal elements of group VIII and / or of group VIB, a hydrogen / charge ratio of between 50 and 5000 Nm3 / m3, preferably included between 100 and 1500 Nm3 / m3 with a still preferred range between 500 and 1300 Nm3 / m3. 3-process for treating a heavy hydrocarbon feedstock according to claim 1, wherein the hydrocracking step comprises two reactors, one operating as a bubbling bed, the other in a hybrid bed. 4- Process for treating a heavy hydrocarbon feedstock according to claim 1, wherein the hydrocracking step comprises two reactors, the two reactors operating in a hybrid bed. 5. Process for treating a heavy hydrocarbon feedstock according to claim 1, wherein the hydrocracking step comprises a single reactor operating in a hybrid bed. 6. Process for treating a heavy hydrocarbon feedstock according to claim 1, wherein the particles constituting the "disperse" catalyst of the hybrid bed have a size of between 10 and 80 microns. 7- A method for treating a heavy hydrocarbon feedstock according to claim 1, wherein the step d) sediment treatment is performed on the heavy effluent from the separation step c), said separation step c) being completed by a final separation step e) placed downstream of the treatment step d). 8- A method for treating a heavy hydrocarbon feedstock according to claim 1, wherein the step d) sediment treatment is performed on the heavy effluent from the separation step c) the said separation step c) being a complete separation, and the heavy cut resulting from the treatment step d) constituting a marine fuel.