EP3018187B1 - Process for converting petroleum feedstocks comprising an ebullating-bed hydrocracking stage, a maturation stage and a stage of separating the sediments for the production of fuel oils with a low sediment content - Google Patents

Description

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 converting heavy petroleum feeds of the atmospheric residue type and / or vacuum residue for the production of heavy fractions that can be used as fuel bases, in particular bunker oil bases, with a low sediment content. The process according to the invention also makes it possible to produce atmospheric distillates (naphtha, kerosene and diesel), vacuum distillates and light gases (C1 to C4).

The quality requirements for marine fuels are described in ISO 8217. The sulfur specification now focuses on SO _x emissions (Annex VI of the MARPOL Convention of the International Maritime Organization) and results in a recommendation for sulfur content not exceeding 0.5% by weight outside the Sulfur Emission Control Areas (ZCES or Emissions Control Areas / ECA) by 2020-2025 and less than or equal to 0,1% in ZCES. According to Annex VI of the MARPOL Convention, the sulfur contents mentioned above are equivalent contents leading to SOx emissions. A ship will therefore be able to use a sulfur fuel oil if the vessel is equipped with a flue gas treatment system that reduces sulfur oxide emissions.

Another very restrictive recommendation is the sediment content after aging according to ISO 10307-2 (also known as IP390) which must be less than or equal to 0.1%.

The sediment content according to ISO 10307-1 (also known as IP375) is different from the sediment content after aging according to ISO 10307-2 (also known as IP390). The sediment content after aging according to ISO 10307-2 is a much more stringent specification and corresponds to the specification for bunker fuels.

On the other hand, terrestrial fuel oils, in particular fuel oils that can be used for the production of heat and / or electricity, may also be subject to specifications of stability, in particular maximum sediment contents, the thresholds of which vary according to the places of production because there is no international harmonization as in the case of maritime transport. There is, however, an interest in reducing the sediment content of terrestrial fuel oils.

Residue hydrocracking processes convert low value residues to higher value added distillates. The resulting heavy fraction corresponding to the unconverted residual cut is generally unstable. It contains sediments that are mainly precipitated asphaltenes. This unstable residual cut can not therefore be valorized as fuel oil, especially as bunker oil without a specific treatment since the hydrocracking is operated under severe conditions leading to a high conversion rate.

The patent US6447671 discloses a process for converting heavy petroleum fractions comprising a first bubbling bed hydrocracking step, a step of removing the catalyst particles contained in the hydrocracking effluent, and then a fixed bed hydrotreating step.

Requirement US2014 / 0034549 discloses a residue conversion process using a bubbling bed hydrocracking step and a step with an upflow reactor associated with a so-called "stripper" reactor. The sediment content of the final effluent is reduced relative to the effluent of the boiling bed stage. However, the sediment content after aging is not less than 0.1% by weight, as required for marketing as a residual type marine fuel.

The patent FR2981659 discloses a petroleum heavy fraction conversion process comprising a first bubbling bed hydrocracking step and a fixed bed hydrotreating step comprising permutable reactors.

The hydrocracking process partially converts heavy feeds to produce atmospheric distillates and / or vacuum distillates. Although ebullated bed technology is known to be suitable for loads The bubbling bed, which is heavy in impurities, is by its nature catalyst fines and sediments that must be removed to satisfy a product quality such as bunker oil. The fines come mainly from the attrition of the catalyst in the bubbling bed.

The sediments may be precipitated asphaltenes. Initially in the feedstock, the hydrocracking conditions and in particular the temperature cause them to undergo reactions (dealkylation, polymerization, etc.) leading to their precipitation. Regardless of the nature of the charge, these phenomena generally occur during the implementation of severe conditions giving rise to conversion rates (for compounds boiling above 540 ° C: 540 + ° C), ie ie greater than 30, 40 or 50% depending on the nature of the load.

The applicant in his research has developed a new process incorporating a step of maturation and separation of sediments downstream of a hydrocracking step. Surprisingly, it has been found that such a method makes it possible to obtain heavy fractions having a low sediment content after aging, said heavy fractions being advantageously able to be used wholly or partly as fuel oil or as a fuel oil base, especially as bunker oil or bun fuel oil to specifications, namely and a sediment content after aging less than or equal to 0.1% by weight.

An advantage of the process according to the invention is to avoid in particular the risk of clogging of the boat engines and in the case of possible processing steps implemented downstream of the hydrocracking step of avoiding clogging of the engine. or catalytic bed (s) used.

1. a) une étape d'hydrocraquage de la charge en présence d'hydrogène dans au moins un réacteur contenant un catalyseur supporté en lit bouillonnant,
2. b) une étape de séparation de l'effluent obtenu à l'issue de l'étape a) en au moins une fraction légère d'hydrocarbures contenant des bases carburants et une fraction lourde contenant des composés bouillant à au moins 350°C,
3. c) une étape de maturation de la fraction lourde issue de l'étape b) de séparation permettant la transformation d'une partie des sédiments potentiels en sédiments existants, réalisée pendant une durée comprise entre 1 et 1500 minutes, à une température comprise entre 50 et 350°C, et une pression inférieure à 20 MPa,
4. d) une étape de séparation des sédiments de la fraction lourde issue de l'étape c) de maturation pour obtenir ladite fraction lourde.

More particularly, the invention relates to a process for converting a hydrocarbon feedstock containing at least one hydrocarbon fraction having a sulfur content of at least 0.1% by weight, an initial boiling temperature of at least 340 ° C and a final boiling temperature of at least 440 ° C to obtain a heavy fraction having a sediment content after aging less than or equal to 0.1% by weight, said process comprising the following steps:

1. a) a step of hydrocracking the feedstock in the presence of hydrogen in at least one reactor containing a catalyst supported in a bubbling bed,
2. b) a step of separating the effluent obtained at the end of step a) into at least a light hydrocarbon fraction containing fuels bases and a heavy fraction containing compounds boiling at least 350 ° C,
3. c) a step of maturation of the heavy fraction resulting from the separation stage b) allowing the transformation of a part of the potential sediments into existing sediments, carried out for a period of between 1 and 1500 minutes, at a temperature of between 50 and and 350 ° C, and a pressure of less than 20 MPa,
4. d) a step of separating the sediments from the heavy fraction resulting from the curing step c) to obtain said heavy fraction.

In order to form the fuel oil in accordance with the viscosity recommendations, the heavy fractions obtained by the present process can be mixed with fluxing bases so as to achieve the target viscosity of the desired fuel grade.

Another point of interest of the process is the partial conversion of the feedstock making it possible to produce, particularly by hydrocracking, atmospheric distillates or vacuum distillates (naphtha, kerosene, diesel, vacuum distillate), which can be used as bases in plants. fuel pools directly or after passing through another refining process such as hydrotreating, reforming, isomerization, hydrocracking or catalytic cracking.

Brief description of Figure 1

The figure 1 illustrates a schematic view of the process according to the invention showing a hydrocracking zone, a separation zone, a zone of ripening and separation of sediments.

detailed description Load

The feedstocks treated in the process according to the invention are advantageously chosen from atmospheric residues, vacuum residues from direct distillation, crude oils, crude head oils, deasphalted oils, deasphalting resins, asphalts or pitches. deasphalting, residues resulting from conversion processes, aromatic extracts from lubricant base production lines, oil sands or their derivatives, oil shales or their derivatives, whether alone or as a mixture.

These fillers can advantageously be used as they are or else diluted by a hydrocarbon fraction or a mixture of hydrocarbon fractions which may be chosen from products resulting from a fluid catalytic cracking process (FCC according to the initials of the English name of "Fluid Catalytic Cracking"), a light cutting oil (LCO), a heavy cutting oil (HCO), a decanted oil (OD according to the initials of the English name "Decanted Oil"), a residue of FCC , or which may come from the distillation, gas oil fractions including those obtained by atmospheric or vacuum distillation, such as vacuum gas oil. The heavy charges can also advantageously comprise cuts from the liquefaction process of coal or biomass, aromatic extracts, or any other hydrocarbon cuts or non-petroleum fillers such as pyrolysis oil.

The fillers according to the invention generally have a sulfur content of at least 0.1% by weight, an initial boiling point of at least 340 ° C. and a final boiling point of at least 440 ° C. preferably a final boiling temperature of at least 540 ° C. Advantageously, the feedstock may contain at least 1% C7 asphaltenes and at least 5 ppm metals, preferably at least 2% C7 asphaltenes and at least 25 ppm metals.

The fillers according to the invention are preferably atmospheric residues or residues under vacuum, or mixtures of these residues.

Step a): Hydrocracking

The filler according to the invention is subjected to a hydrocracking step which is carried out in at least one reactor containing a catalyst supported in a bubbling bed and preferably operating with an upward flow of liquid and gas. The objective of the hydrocracking step is to convert the heavy fraction into lighter cuts while partially refining the charge.

The ebullated bed technology being widely known, only the main operating conditions will be repeated here.

Bubbling bed technologies use extruded bed catalysts supported in the form of extrudates with a diameter generally of the order of 1 mm or less than 1 mm. The catalysts remain inside the reactors and are not evacuated with the products. The temperature levels are high in order to obtain high conversions while minimizing the amounts of catalysts used. The catalytic activity can be kept constant by replacing the catalyst in line. It is therefore not necessary to stop the unit to change the spent catalyst, nor to increase the reaction temperatures along the cycle to compensate for the deactivation. In addition, operating at constant operating conditions provides consistent yields and product qualities along the cycle. Also, because the catalyst is kept agitated by a large recycling of liquid, the pressure drop on the reactor remains low and constant.

The conditions of hydrocracking step a) in the presence of hydrogen are usually conventional bubbling bed hydrocracking conditions of a liquid hydrocarbon fraction. It is advantageously carried out under a hydrogen partial pressure of 5 to 35 MPa, often 8 to 25 MPa and usually 12 to 20 MPa at a temperature of 330 to 500 ° C and often 350 to 450 ° C. Hourly space velocity (VVH) and hydrogen partial pressure are factors important that one chooses according to the characteristics of the product to be treated and the desired conversion. The VVH, defined as the volumetric flow rate of the feed divided by the total volume of the reactor, is generally in a range from 0.05 h ^-1 to 5 h ^-1 , preferably from 0.1 h ^-1 to 2 h ^-1 and more preferably from 0.2 h ^-1 to 1 h ^-1 . The amount of hydrogen mixed with the feedstock is usually 50 to 5000 Nm ³ / m ³ (normal cubic meters (Nm ³ ) per cubic meter (m ³ ) of liquid feed) and usually 100 to 1000 Nm ³ / m ³ and preferably from 200 to 500 Nm ³ / m ³ .

It is possible to use a conventional granular hydrocracking catalyst 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 of molybdenum of preferably from 5 to 20% by weight of molybdenum (expressed as MoO ₃ molybdenum oxide) on an amorphous mineral support. This support will for example be chosen from the group formed by 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 chosen from the group formed by boron oxide, zirconia, titanium oxide and 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 P ₂ O ₅ is present, its concentration is usually less than 20% by weight and most often less than 10% by weight. The concentration of boron trioxide B ₂ O ₃ is usually from 0 to 10% by weight. The alumina used is usually a gamma or eta alumina. This catalyst is most often in the form of extrudates. The total content of Group VI and VIII metal oxides is often from 5 to 40% by weight and generally from 7 to 30% by weight and the weight ratio expressed as oxide Group VI metal (or metals) metal on metal (or metals) Group VIII is generally 20 to 1 and most often 10 to 2.

The spent catalyst is partly replaced by fresh catalyst, generally by withdrawal at the bottom of the reactor and introduction to the top of the fresh or new catalyst reactor at a regular time interval, that is to say for example by puff or almost keep on going. 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 unit usually comprises a recirculation pump for maintaining the bubbling bed catalyst by continuously recycling 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 a).

Most often the hydrocracking step a) is carried out under the conditions of the H-OIL® process as described, for example, in US6270654 .

The hydrocracking can be carried out in a single reactor or in several (generally two) reactors arranged in series. The use of at least two ebullated bed reactors in series makes it possible to obtain products of better quality and with a better yield, thus limiting the energy and hydrogen needs in possible post-treatments. In addition, the hydrocracking into two reactors makes it possible to have improved operability in terms of the flexibility of the operating conditions and of the catalytic system. Generally, the temperature of the second reactor is preferably at least 5 ° C higher than that of the first bubbling bed reactor. The pressure of the second reactor is 0.1 to 1 MPa lower than for the first reactor to allow the flow of at least a portion of the effluent from the first step without pumping is necessary. The Different temperature operating conditions in the two hydrocracking reactors are selected to control hydrogenation and feed conversion to the desired products in each reactor. Optionally, the effluent obtained at the end of the first hydrocracking reactor is subjected to a separation of the light fraction and at least a portion, preferably all, of the residual effluent is treated in the second hydrocracking reactor .

This separation can be performed in an inter-floor separator as described in the patent US 6270654 and in particular makes it possible to avoid excessive hydrocracking of the light fraction in the second hydrocracking reactor.

It is also possible to transfer all or part of the used catalyst withdrawn from the first hydrocracking reactor, operating at a lower temperature, directly into the second hydrocracking reactor, operating at a higher temperature or to transfer in whole or in part the used catalyst withdrawn from the second hydrocracking reactor directly to the first hydrocracking reactor. This cascade system is described in the patent US4816841 .

The hydrocracking step may also be carried out in at least one reactor operating in a hybrid bed mode, that is to say operating in a bubbling bed with a supported catalyst associated with a dispersed catalyst consisting of very fine catalyst particles. forming a suspension with the charge to be treated.

A hybrid bed has two populations of catalyst, a population of bubbling bed catalyst to which is added a population of "dispersed" type catalyst. The term "dispersed" refers to an implementation of the reactor in which the catalyst is in the form of very fine particles, that is to say generally a size of between 1 nanometer (ie 10 ^-9 m) and 150 microns, preferably between 0.1 and 100 microns, and even more preferably between 10 and 80 microns.

In a first variant, the hydrocracking stage may comprise a first bubbling bed reactor followed by a second hybrid bed type reactor (that is to say bubbling bed type with "dispersed" type catalyst injection). .

In a second variant, the hydrocracking step may comprise a first hybrid bed type reactor followed by a second hybrid type reactor

In a third variant, the hydrocracking step may comprise a single hybrid bed type reactor.

The "disperse" catalyst used in the hybrid bed reactor may be 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, a non-noble group VIIIB element (Co, Ni, Fe) and a group VIB element (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 mixture of Mo or Ni oxide. With aqueous ammonia, the catalysts used are preferably derived from soluble precursors in an organic phase (oil-soluble catalysts).

The precursors are generally 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 , Mo or Ni acetylacetonates, C7-C12 fatty acid salts of Mo or W, etc. They can be used in the presence of a surfactant to improve the dispersion of 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 and its nature. In all cases, the precursor is sulfided (ex-situ or in-situ) to form the catalyst dispersed in the feedstock.

For the case of so-called oil-soluble catalysts, the precursor is advantageously mixed with a carbonaceous feedstock (which may be a 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 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 catalyst or to the "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 Ni, Co) and / or at least one group VIB element (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 reaction zone of the "dispersed" hydrocracking process is between 0 and 10 wt.%, Preferably between 1 and 3 wt.%, And 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.

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 supported catalyst particles are fluidized but not transported, so that these particles remain in the bubbling bed reactor (with the exception of catalyst fines that can be formed by attrition and entrained with the liquid since these fines are small). In the case of a hybrid bed, the "dispersed" type catalyst is also entrained with the liquid since the "dispersed" type catalyst consists of particles of very small size.

Step b): Separation of the hydrocracking effluent

The effluent obtained at the end of the hydrocracking step a) undergoes at least one separation step, optionally supplemented by further additional separation steps, making it possible to separate at least one light hydrocarbon fraction containing bases. fuels and a heavy fraction containing boiling compounds at least 350 ° C.

The separation step may advantageously be carried out by any method known to those skilled in the art such as, for example, the combination of one or more high and / or low pressure separators, and / or distillation stages and / or or high and / or low pressure stripping. Preferably, the separation step b) makes it possible to obtain a gaseous phase, at least a light fraction of hydrocarbons of the type naphtha, kerosene and / or diesel, a vacuum distillate fraction and a vacuum residue fraction and / or an atmospheric residue fraction.

The separation may be carried out in a fractionation section which may first comprise a high temperature high pressure separator (HPHT), and optionally a low temperature high pressure separator (HPBT), and / or atmospheric distillation and / or distillation under empty. The effluent obtained at the end of step a) is separated (generally in an HPHT separator) into a light fraction and a heavy fraction containing predominantly boiling compounds at least 350 ° C. The cutting point of the separation is advantageously between 200 and 400 ° C.

In a variant of the process of the invention, during step b), the effluent from the hydrocracking may also undergo a succession of flashes comprising at least one high temperature high pressure balloon (HPHT) and a low pressure balloon high temperature (BPHT) for separating a heavy fraction which is sent in a steam stripping step for removing from said heavy fraction at least a light fraction rich in hydrogen sulfide. The heavy fraction recovered at the bottom of the stripping column contains compounds boiling at least 350 ° C. but also atmospheric distillates. According to the process of the invention, said heavy fraction separated from the light fraction rich in hydrogen sulphide is then sent to the maturation step c) and then to the sediment separation step d).

In a variant, at least a portion of the so-called heavy fraction from step b) is fractionated by atmospheric distillation into at least one atmospheric distillate fraction containing at least one light fraction of naphtha, kerosene and / or diesel type hydrocarbons. and an atmospheric residue fraction. At least a part of the atmospheric residue fraction can be sent in the maturation step c) and then in the sediment separation step d).

The atmospheric residue can also be at least partially fractionated by vacuum distillation into a vacuum distillate fraction containing vacuum gas oil. and a residue fraction under vacuum. Said fraction vacuum residue is advantageously sent at least partly in the maturation step c) and then in the sediment separation step d).

At least a portion of the vacuum distillate and / or the vacuum residue may also be recycled to the hydrocracking step a).

Irrespective of the separation method used, the light fraction (s) obtained may (may) undergo further separation steps, possibly in the presence of the light fraction obtained from the internal separator. stage between the two hydrocracking reactors. Advantageously, it (s) is (are) subject (s) to atmospheric distillation to obtain a gaseous fraction, at least a light fraction of naphtha, kerosene and / or diesel type hydrocarbons and a vacuum distillate fraction.

Part of the atmospheric distillate and / or the vacuum distillate from the separation step b) may constitute a part of a fuel oil as a fluxing agent. These cuts can also be marine fuels with low viscosity (MGO or MGO, Marine Diesel Oil or Marine Gas Oil according to English terminology). Another part of the vacuum distillate can still be upgraded by hydrocracking and / or catalytic cracking in a fluidized bed.

The gaseous fractions resulting from the separation step preferably undergo a purification treatment to recover the hydrogen and recycle it to the hydrocracking reactors (step a)).

The recovery of different fuel base cuts (LPG, naphtha, kerosene, diesel and / or vacuum gas oil) obtained from the present invention is well known to those skilled in the art. The products obtained can be integrated in fuel tanks (also called "pools" fuels according to the English terminology) or undergo additional refining steps. The fraction (s) naphtha, kerosene, gas oil and vacuum gas oil may be subjected to one or more treatments (hydrotreatment, hydrocracking, alkylation, isomerization, catalytic reforming, catalytic cracking or thermal or other) to bring them to the specifications. required (sulfur content, smoke point, octane, cetane, etc ...) separately or in mixture.

Advantageously, the vacuum distillate leaving the bubbling bed after separation can be hydrotreated. This hydrotreated vacuum distillate may be used as a fluxing agent for the fuel oil pool having a sulfur content of less than or equal to 0.5% by weight or may be used directly as oil with a sulfur content of less than or equal to 0.1% by weight.

Part of the atmospheric residue, vacuum distillate and / or vacuum residue may undergo further refining steps, such as hydrotreatment, hydrocracking, or fluidized catalytic cracking.

Step c): Maturation of the sediments

The heavy fraction obtained at the end of the separation step b) contains organic sediments which result from the hydrocracking conditions and the catalyst residues. Part of the sediments consist of asphaltenes precipitated under hydrocracking conditions and are analyzed as existing sediments (IP375).

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. However, high hydrocracking conditions, that is to say when the conversion rate is for example greater than 30, 40 or 50% depending on the load, cause the formation of existing sediments and potential sediments.

In order to obtain a fuel oil or base of reduced sediment fuel oil, in particular bunker oil or bunker oil base meeting the recommendations for a sediment content after aging (IP390) less than or equal to 0.1 %, the method according to the invention comprises a maturation step making it possible to improve the sediment separation efficiency and thus to obtain fuels or bases of stable fuels, that is to say a sediment content after aging less than or equal to 0.1% by weight.

The maturation step according to the invention makes it possible to form all the existing and potential sediments (by converting the potential sediments into existing sediments) so as to separate them more efficiently and thus respect the sediment content after aging (IP390) of 0.1% maximum weight.

The curing stage according to the invention is advantageously carried out for a residence time of between 1 and 1500 minutes, preferably between 25 and 300 minutes, more preferably between 60 and 240 minutes, at a temperature between 50 and 350 ° C, preferably between 75 and 300 ° C and more preferably between 100 and 250 ° C, a pressure advantageously less than 20 MPa, preferably less than 10 MPa, more preferably less than 3 MPa and even more preferentially lower at 1.5 MPa.

The ripening step may be carried out using an exchanger or a heating furnace followed by one or more capacity (s) in series or in parallel such (s) as a horizontal or vertical balloon, optionally with a settling function to remove some of the heavier solids, and / or a piston reactor. A stirred and heated tank may also be used, and may be provided with a bottom draw to remove some of the heavier solids.

Advantageously, step c) of maturation of the heavy fraction resulting from step b) is carried out in the presence of an inert gas and / or an oxidizing gas.

The c) maturation step is carried out in the presence of an inert gas such as nitrogen, or in the presence of an oxidizing gas such as oxygen, or in the presence of a mixture containing an inert gas and a gas oxidant such as air or air depleted by nitrogen. The use of an oxidizing gas accelerates the maturation process.

In the case where the maturation stage is carried out in the presence of an inert and / or oxidizing gas, said gas is mixed with the heavy fraction resulting from stage b) before the stage of maturation and separation of this gas after the maturation of to obtain a liquid fraction at the end of the c) stage of maturation. Such a gas / liquid implementation can for example be carried out in a bubble column. According to another embodiment, the inert and / or oxidizing gas may also be introduced during the d) stage of maturation, for example by means of a bubbling (injection of gas from below) in a stirred tank which allows to promote gas / liquid contact.

At the end of the curing step c), at least one hydrocarbon fraction with an enriched content of existing sediments is obtained which is sent to step d) of separation of the sediments.

Step d) : Separation sediment

The method according to the invention further comprises a step d) of separating sediments and catalyst residues.

The heavy fraction obtained at the end of the curing step c) contains precipitated asphaltene-type organic sediments which result from the hydrocracking and maturation conditions. This heavy fraction may also contain catalyst fines resulting from the attrition of extruded type catalysts in the implementation of hydrocracking reactor. This heavy fraction may optionally contain "dispersed" catalyst residues in the case of the implementation of a hybrid reactor.

Thus, at least a portion of the heavy fraction resulting from the curing step c) is subjected to a separation of the sediments and the catalyst residues, by means of at least one physical separation means chosen from a filter, a membrane separation, a bed of organic or inorganic type filtering solids, electrostatic precipitation, a centrifugation system, decantation, auger withdrawal. A combination, in series and / or in parallel, of several separation means of the same type or different type can be used during this step d) separation of sediments and catalyst residues. One of these solid-liquid separation techniques may require the periodic use of a light rinsing fraction, resulting from the process or not, allowing for example the cleaning of a filter and the evacuation of sediments.

The heavy fraction resulting from step d) with a reduced sediment content can advantageously be used as a base for fuel oil or as fuel oil, in particular as a bunker oil or bunker oil base, having a sediment content after aging of less than 0, 1% weight Advantageously, said heavy fraction is mixed with one or more fluxing bases selected from the group consisting of catalytic cracking light cutting oils, catalytic cracking heavy cutting oils, catalytic cracking residue, kerosene, a gas oil, a vacuum distillate and / or a decanted oil.

Step e) optional : optional separation step,

The effluent obtained at the end of step d) of separation of the sediments can undergo an optional separation step making it possible to separate at least a light fraction of hydrocarbons containing fuels bases and a heavy fraction containing predominantly at least 350 ° C.

This separation step can advantageously be carried out by any method known to those skilled in the art such as, for example, the combination of one or more high and / or low pressure separators, and / or distillation and / or distillation stages. high and / or low pressure stripping. This optional step e) of separation is similar to the separation step b) and will not be further described.

Preferably, this separation step makes it possible to obtain at least a light fraction of hydrocarbons of the naphtha, kerosene and / or diesel type, a vacuum distillate fraction and a vacuum residue fraction and / or an atmospheric residue fraction.

Part of the atmospheric residue and / or the vacuum residue can also be recycled to the hydrocracking step a).

Step f) : Optional hydrotreatment step

The sulfur content of the heavy fraction resulting from step d) or e) when the latter is used, and containing predominantly compounds boiling at least 350 ° C, depends on the operating conditions of the step of hydrocracking but also the sulfur content of the original charge.

Thus, for low sulfur feeds, generally less than 1.5% by weight, it is possible to directly obtain a heavy fraction with less than 0.5% by weight sulfur as required for vessels without treatment. fumes and operating outside the ZCSEs by 2020-2025.

For more sulfurous feedstocks, whose sulfur content is generally greater than 1.5% by weight, the sulfur content of the heavy fraction may exceed 0.5% by weight. In such a case, a step f) of hydrotreatment in a fixed bed is made necessary in the case where the refiner wishes to reduce the sulfur content, in particular for a bunker oil base or a bunker oil intended to be burned on a ship without smoke treatment.

The f) fixed bed hydrotreatment step is carried out on at least a portion of the heavy fraction resulting from step d) or e) when step e) is implemented. The heavy fraction from step f) can advantageously be used as a base of fuel oil or as fuel oil, especially as a base of bunker oil or as bunker oil, having a sediment content after aging less than 0.1% by weight. Advantageously, said heavy fraction is mixed with one or more fluxing bases selected from the group consisting of catalytically cracked light cutting oils, catalytically cracked heavy cutting oils, catalytic cracking residue, kerosene, a gas oil, a vacuum distillate and / or a decanted oil.

The heavy fraction resulting from the sediment separation step d) or e) when step e) is carried out is sent to the hydrotreatment step f) comprising one or more hydrotreatment zones in fixed beds. The sending in a fixed bed of a heavy fraction devoid of sediments constitutes an advantage of the the present invention since the fixed bed will be less subject to clogging and increased pressure drop.

Hydroprocessing (HDT) is understood to mean, in particular, hydrodesulphurization (HDS) reactions, hydrodenitrogenation (HDN) reactions and hydrodemetallation (HDM) reactions, but also hydrogenation, hydrodeoxygenation, hydrodearomatization, hydrodenetration, hydroisomerization, hydrodealkylation, hydrocracking, hydro-deasphalting and Conradson carbon reduction.

Such a method of hydrotreating heavy cuts is widely known and can be related to the process known as HYVAHL-F ™ described in US Pat. US5417846 .

The person skilled in the art easily understands that in the hydrodemetallization stage, hydrodemetallation reactions are mainly carried out but also part of the hydrodesulfurization reactions. Similarly, in the hydrodesulfurization step, hydrodesulphurization reactions are mainly carried out but also part of the hydrodemetallation reactions.

According to one variant, a co-charge may be introduced with the heavy fraction in the hydrotreatment step f). This co-charge can be chosen from atmospheric residues, vacuum residues from direct distillation, deasphalted oils, aromatic extracts from lubricant base production lines, hydrocarbon fractions or a mixture of hydrocarbon fractions that can be chosen. Among the products resulting from a process of fluid catalytic cracking in a fluid bed: a light cutting oil (LCO), a heavy cutting oil (HCO), a decanted oil, or possibly derived from distillation, the gasoil fractions in particular those obtained by atmospheric or vacuum distillation, such as, for example, vacuum gas oil.

The hydrotreatment step can advantageously be carried out at a temperature of between 300 and 500 ° C., preferably 350 ° C. to 420 ° C. and under a hydrogen partial pressure advantageously between 2 MPa and 25 MPa, preferably between 10 and 20 MPa, an overall hourly space velocity (VVH) is ranging from 0.1 h -1 to 5 h -1 and preferably from 0.1 h -1 to 2 h -1, a quantity of hydrogen mixed with the feed usually of 100 to 5000 Nm 3 / m 3 (normal cubic meters (Nm3) per cubic meter (m3) of liquid charge), most often from 200 to 2000 Nm3 / m3 and preferably from 300 to 1500 Nm3 / m3.

Usually, the hydrotreating step is carried out industrially in one or more liquid downflow reactors. The hydrotreatment temperature is generally adjusted according to the desired level of hydrotreatment.

The hydrotreatment catalysts used are preferably known catalysts and are generally granular catalysts comprising, on a support, at least one metal or metal compound having a hydrodehydrogenating function. These catalysts are advantageously catalysts comprising at least one Group VIII metal, generally selected from the group consisting of nickel and / or 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 and preferably from 1 to 5% by weight of nickel (expressed as nickel oxide NiO) and from 1 to 30% by weight of molybdenum, preferably from 5 to 20% by weight of molybdenum (expressed as molybdenum oxide MoO ₃ ) on a mineral support. This support will, for example, be selected from the group formed by alumina, silica, silica-aluminas, magnesia, clays and mixtures of at least two of these minerals. Advantageously, this support contains other doping compounds, in particular oxides chosen from the group formed by boron oxide, zirconia, ceria, titanium oxide, phosphoric anhydride and a mixture of these oxides. Most often an alumina support is used and very often a support of alumina doped with phosphorus and possibly boron. The concentration of phosphorus pentoxide P ₂ O ₅ is usually between 0 or 0.1% and 10% by weight. The concentration of boron trioxide B ₂ O ₅ is usually between 0 or 0.1% and 10% by weight. The alumina used is usually a γ or η alumina. This catalyst is most often in the form of extrudates. The total content of Group VIB and VIII metal oxides is often 5 to 40% by weight and in general 7 at 30% by weight and the weight ratio expressed as metal oxide between metal (or metals) of group VIB on metal (or metals) of group VIII is generally from 20 to 1 and most often from 10 to 2.

In the case of a hydrotreatment step including a hydrodemetallation step (HDM), then a hydrodesulfurization step (HDS), it is most often used specific catalysts adapted to each step.

Catalysts that can be used in the hydrodemetallation (HDM) stage are for example indicated in the patents EP113297 , EP113284 , US5221656 , US5827421 , US7119045 , US5622616 and US5089463 . Hydrodemetallation (HDM) catalysts are preferably used in the reactive reactors. Catalysts that can be used in the hydrodesulfurization (HDS) step are, for example, indicated in the patents EP113297 , EP113284 , US6589908 , US4818743 or US6332976 . It is also possible to use a mixed catalyst that is active in hydrodemetallization and in hydrodesulfurization for both the hydrodemetallation (HDM) section and the hydrodesulfurization (HDS) section as described in the patent. FR2940143 .

Prior to the injection of the feed, the catalysts used in the process according to the present invention are preferably subjected to an in-situ or ex-situ sulphurization treatment .

Step g): Optional step of separation of the hydrotreatment effluent

The optional separation step g) may advantageously be carried out by any method known to those skilled in the art such as, for example, the combination of one or more high and / or low pressure separators, and / or distillation and / or high and / or low pressure stripping. This optional separation step g) is similar to the separation step b) and will not be further described.

In an alternative embodiment of the invention, the effluent obtained in step f) may be at least partly, and often entirely, sent to a separation step g), comprising atmospheric distillation and / or distillation under empty. The effluent of the hydrotreatment stage is fractionated by atmospheric distillation into a gaseous fraction, at least one atmospheric distillate fraction containing the fuels bases (naphtha, kerosene and / or diesel) and an atmospheric residue fraction. At least a portion of the atmospheric residue can then be fractionated by vacuum distillation into a vacuum distillate fraction containing vacuum gas oil and a vacuum residue fraction.

The vacuum residue fraction and / or the vacuum distillate fraction and / or the atmospheric residue fraction may be at least partly the bases of low-sulfur fuel oils having a sulfur content of less than or equal to 0.5% by weight and a sediment content after aging less than or equal to 0.1%. The vacuum distillate fraction can constitute a fuel oil base having a sulfur content of less than or equal to 0.1% by weight.

Part of the vacuum residue and / or the atmospheric residue can also be recycled to the hydrocracking step a).

fluxing

To obtain a fuel oil, the heavy fractions resulting from steps d) and / or e) and / or f) and / or g) can be mixed with one or more fluxing bases chosen from the group consisting of light cutting oils. catalytic cracking, catalytically cracked heavy cutting oils, catalytic cracking residue, kerosene, gas oil, vacuum distillate and / or decanted oil. Preferably, kerosene, gas oil and / or vacuum distillate produced in the process of the invention will be used. Advantageously, kerosene, gas oil and / or vacuum distillate obtained in process separation steps b) or g) will be used.

Detailed description of Figure 1

The figure 1 represents an example of implementation according to the invention without limiting the scope thereof.

In the figure 1 the charge (10), preheated in the enclosure (92), mixed with recycled hydrogen (14) and makeup hydrogen (90) preheated in the enclosure (91), is introduced by the pipe (96) in the hydrocracking step at the bottom of the first bubbling bed reactor (98) operating at an upward flow of liquid and gas and containing at least one supported hydrocracking catalyst. Advantageously, a co-charge (94) can be introduced. Advantageously, the first bubbling bed reactor operates in hybrid mode, the "dispersed" type catalyst is then introduced via line (100) upstream of the first hydrocracking reactor (98).

Advantageously, 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 from (110) 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 bubbling bed operating at an upward flow of liquid and gas containing at least one hydrocracking catalyst of the supported type. Advantageously, the second bubbling bed reactor operates in hybrid mode, the "dispersed" type catalyst is then injected upstream of the first reactor (98) in the case of two hybrid reactors in series, or the "dispersed" type catalyst. is injected upstream of the second reactor (102) via a pipe not shown in the case of a first bubbling bed reactor followed in the second hybrid reactor.

The operating conditions, in particular the temperature, in this reactor are chosen to reach the desired conversion level, as previously described.

The effluent from the hydrocracking reactors is sent via line (134) into a high temperature high pressure (HPHT) separator (136) from which a gaseous fraction (138) and a heavy fraction (140) are recovered. Fraction gas (138) is generally supplied 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 the gases is recovered ( H2, H2S, NH3, C1-C4 hydrocarbons ...) and a liquid fraction (148).

The gaseous fraction (146) of the low temperature high pressure separator (HPBT) (144) can be processed in a 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. Gases containing undesirable nitrogen and sulfur compounds are removed from the plant (flow (158) which may represent a plurality of streams, in particular a flow rich in H 2 S and one or more purges containing light hydrocarbons) The liquid fraction (148) of the separator High temperature low pressure (HPBT) (144) is advantageously relaxed in the device (160) to be sent to the fractionation system (172).

The heavy fraction (140) resulting from the high temperature high pressure separation (HPHT) (136) is advantageously relaxed in the device (174) and then 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 (not shown ), and a liquid phase which is fed to the fractionation section (172).

Fractions (148) and (140) may 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 fraction (180). ). 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 vacuum gas oil .

The atmospheric residue fraction (182) and / or the vacuum residue fraction (186) are subjected to a stage of maturation and separation of sediments and catalyst residues in order to constitute desired oil bases.

An atmospheric residue (182) fraction is optionally preheated in an oven or exchanger (205) to achieve the temperature necessary for maturation (conversion of potential sediments into existing sediments) that occurs 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 type fraction (186) is optionally preheated in an oven or exchanger (213) so as to reach the temperature necessary for the maturation that 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 stirred stirred tank according to an embodiment not shown.

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 inert or oxidizing gas, or a mixture inert gas and oxidizing gas. In case of use of gas during maturation, a device not shown will separate the gas from the liquid. According to a mode not shown, it is also possible to carry out a step of maturation and separation of the sediments and catalyst residues on a heavy fraction resulting from the hydrocracking effluent separation step, for example on a heavy cut from a separator, for example on the flow (140) before or after the expansion (174). An advantageous mode not shown may consist in operating the stage of maturation and separation of the sediments on the stream recovered at the bottom of a stripping column. When the stage of maturation 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-sediment fuels. Some of the streams (188) and / or (212) and / or (219), before or after the optional sediment ripening and separation step, may be recycled via line (190) to step hydrocracking.

EXAMPLES:

The following example illustrates the invention without limiting its scope. The treated feed is a vacuum residue (RSV Ural) whose characteristics are shown in Table 1. <u> Table 1: Characteristics of the load </ u> Chopped off RSV Urals Density 15/4 1,018 Sulfur% mass 2.60 Conradson Carbon 14 Asphalenes C7 (% by mass) 4.1 NI + V ppm 172 350 ° C + (% mass of compounds boiling above 350 ° C) 97.5 540 ° C + (% mass of compounds boiling above 540 ° C) 70.3

The feed is subjected to a hydrocracking step in two successive bubbling bed reactors.

According to a variant made in a second experiment, the two boiling bed reactors are operated in hybrid mode, that is to say using a dispersed catalyst injected at the inlet of the first reactor in addition to the supported catalysts. The operating conditions of the hydrocracking section are given in Table 2.

The NiMo catalyst on Alumina used is sold by the company Axens under the reference HOC458. <u> Table 2: Operating conditions hydrocracking section </ u> 2 bubbling beds 2 hybrid bubbling beds Catalyst NiMo on Alumina NiMo on Alumina + Mo Naphenate Bubbling bed temperature R1 (° C) 420 420 Boiling bed temperature R2 (° C) 425 425 Partial hydrogen pressure, MPa 15 15 VVH _C (Sm ³ / h load / m ³ supported catalysts), h ^-1 0.55 0.55 VVH _R (Sm ³ / h charge / m ³ reactors), h ^-1 0.3 0.3 Dispersed Catalyst Concentration (ppm precursor in charge input hybrid beds) 0 100 H ₂ input (Nm ³ / m ³ load) 600 600 VVH _C : ratio between the hourly volume flow rate of charge and the volume of catalysts supported without boiling
WH _R : ratio between the hourly volume flow rate of charge and the volume of reactors

1. A) Pas de traitement supplémentaire (non-conforme à l'invention)
2. B) Une étape de maturation des sédiments (4h à 150°C réalisée dans une cuve agitée chauffée en présence d'un mélange air/azote 50/50 sous une pression de 0,5 MPa) puis une étape de séparation physique des sédiments à l'aide d'un filtre (conforme à l'invention)

The hydrocracking effluents are then subjected to a separation comprising an atmospheric distillation and making it possible to recover a gaseous fraction and a heavy fraction. The heavy fraction (350 ° C + fraction) is then treated according to two variants:

1. A) No additional treatment (not in accordance with the invention)
2. B) A stage of sediment maturation (4 hours at 150 ° C. carried out in a stirred tank heated in the presence of a 50/50 air / nitrogen mixture at a pressure of 0.5 MPa) and then a stage of physical separation of the sediments at using a filter (according to the invention)

According to the two preceding variants A) and B), the 350 ° C + fractions are distilled in the laboratory in order to know the qualities and yields of vacuum distillate and vacuum residue. The yields as well as the sulfur content and the viscosity (for heavy cuts) according to the two embodiments of the hydrocracking stage (bubbling beds or hybrid beds) are indicated in Table 3. <u> Table 3: Yields, Sulfur Content and Bubbling Chamber Viscosity (% w / w) </ u> 2 bubbling beds 2 hybrid bubbling beds products Yield (% wt) S (% wt) Viscosity at 100 ° C (Cst) Yield (% wt) S (% wt) Viscosity at 100 ° C (Cst) NH ₃ 0.08 0.08 H ₂ S 2.29 2.30 C1-C4 (gas) 3.94 4.62 Naphtha (PI-180 ° C) 9.53 0.07 11,70 0.12 Diesel (180-350 ° C) 24.81 0.17 28.87 0.20 Vacuum distillates (350-540 ° C) 39,73 0.45 7.4 36.12 0.51 7.2 Vacuum residue (540 + ° C) 21.13 0.76 277 17.93 0.88 579 Sum 101.51 101.61 H ₂ consumed (% w / w) 1.51 1.61 Charge stage of ripening: sum of the yields Distillates under vacuum (350-540 ° C) and Residue under vacuum (540 + ° C) 60.86 0.56 54.05 0.63 Yield = Yield, wt = weight

$$\mathrm{Taux\; de\; Hydrodésulfuration}=\left(\left(\mathrm{quantité\; de\; soufre\; de\; la\; charge}-\mathrm{quantité\; de\; soufre\; de\; l}\prime \mathrm{éffluent}\right)/\mathrm{quantité\; de\; soufre\; de\; la\; charge}\right)$$

The operating conditions of the hydrocracking stage coupled with a stage of maturation and separation of the sediments according to the invention carried out on the heavy fraction resulting from atmospheric distillation have an impact on the stability of the effluents obtained. This is illustrated by the post-aging sediment contents measured in the atmospheric residues (350 ° C + cut). The performance is summarized in Table 4 below. <u> Table 4: Summary of performance with or without sediment ripening and separation </ u> Hydrocracking 2 bubbling beds (420/425 ° C) Hydrocracking 2 hybrid bubbling beds (420/425 ° C) Hydrodesulfurization rate (%) 78.5 75.8 Conversion rate (%) 70 74.5 Maturation No Yes No Yes Separation of sediments No Yes No Yes Sediment content after aging (IP390) in the 350 ° C + section 0.8 <0.1 0.7 <0.1 $$\mathrm{Conversion\; rate}=\left(\left(\mathrm{amount\; of\; cut}540\mathrm{°\; C}+\mathrm{of\; charge}-\mathrm{amount\; of\; cut}540\mathrm{°\; C}+\mathrm{of\; the}\text{'}\mathrm{effluent}\right)/\left(\mathrm{amount\; of\; cut}540\mathrm{°\; C}+\mathrm{of\; charge}\right)\right)$$

$$\mathrm{Hydrodesulfurization\; rate}=\left(\left(\mathrm{amount\; of\; sulfur\; from\; the\; load}-\mathrm{amount\; of\; sulfur\; from\; the}\text{'}\mathrm{effluent}\right)/\mathrm{amount\; of\; sulfur\; from\; the\; load}\right)$$

According to the invention, whether the hydrocracking step is carried out with two bubbling beds or two hybrid beds, it is possible to obtain stable effluents with a low sediment content as soon as a maturation step and then a step of separation of sediments are implemented.

It is also possible to subject the effluents from the ripening and sediment separation stages to a fixed bed hydrotreatment stage. The operating conditions of the hydrotreatment step are shown in Table 5.

The CoMoNi catalysts on Alumina used are sold by the company Axens under the references HF858, HM848 and HT438. Table 5: Operating conditions of the hydrotreatment stage carried out on sections 350+ from the hydrocracking step after their passage to the stage of maturation and separation of sediments </ u> HDM and HDS catalysts CoMoNi on alumina Cycle start temperature (° C) 370 H2 partial pressure (MPa) 15 VVH (h-1, Sm3 / h fresh load / m3 fixed bed catalyst) 0.21 H2 / HC inlet section fixed bed excluding H2 consumption (Nm3 / m3 fresh load) 1000

The effluents from the hydrotreating step are then separated and analyzed. The vacuum distillate fractions contain less than 0.2% by weight of sulfur. The fractions under vacuum contain less than 0.5% by weight of sulfur. Thus, vacuum distillate fractions and vacuum residues (or atmospheric residue fractions) with low sulfur content and low sediment content after aging are obtained. These fractions thus constitute excellent fuel oil bases and in particular excellent fuel oil bases.

Claims (15)

1. Process for converting a hydrocarbon-containing feedstock containing at least one hydrocarbon fraction having a sulphur content of at least 0.1% by weight, an initial boiling temperature of at least 340°C and a final boiling temperature of at least 440°C, making it possible to obtain a heavy fraction having a sediment content after ageing of less than or equal to 0.1 % by weight, said process comprising the following stages:

   a) a stage of hydrocracking the feedstock in the presence of hydrogen in at least one reactor containing a supported catalyst in an ebullating bed,

   b) a stage of separating the effluent obtained at the end of stage a) into at least one light hydrocarbon fraction containing fuel bases and a heavy fraction containing compounds boiling at at least 350°C,

   c) a stage of maturation of the heavy fraction originating from the separation stage b) making it possible to convert a part of the potential sediments to existing sediments, carried out for a duration comprised between 1 and 1500 minutes, at a temperature comprised between 50 and 350°C, and at a pressure of less than 20 MPa,

   d) a stage of separating the sediments from the heavy fraction originating from the maturation stage c) in order to obtain said heavy fraction.
2. Process according to claim 1 in which the hydrocracking stage a) is carried out at a partial pressure of hydrogen of 5 to 35 MPa, at a temperature of 330 to 500°C, a space velocity ranging from 0.05 h-1 to 5 h-1 and the quantity of hydrogen mixed with the feedstock is from 50 to 5000 Nm3/m3.
3. Process according to claim 1 or 2 in which the hydrocracking stage is carried out in at least one reactor operating in hybrid bed mode, i.e. operating using an ebullating bed with a supported catalyst combined with a dispersed catalyst constituted by very fine particles of catalyst, all forming a suspension with the feedstock to be treated.
4. Process according to one of the preceding claims in which the stage of maturation of the heavy fraction originating from stage b) is carried out in the presence of an inert gas and/or an oxidizing gas.
5. Process according to one of the preceding claims in which the separation stage d) is carried out by means of at least one separation means selected from a filter, a separation membrane, a filtering bed of solids of the organic or inorganic type, an electrostatic precipitation, a centrifugation system, decantation, drawing-off by means of an endless screw.
6. Process according to one of the preceding claims in which at least a part of the fraction known as heavy originating from stage b) is fractionated by atmospheric distillation into at least one atmospheric distillate fraction containing at least one light hydrocarbon fraction of the naphtha, kerosene and/or diesel type and an atmospheric residue fraction.
7. Process according to one of the preceding claims in which the effluent obtained at the end of the stage d) of separating the sediments undergoes a separation stage e) making it possible to separate at least one light hydrocarbon fraction containing fuel bases and a heavy fraction containing mainly compounds boiling at at least 350°C.
8. Process according to claim 7 also comprising a fixed-bed hydrotreatment stage f) implemented on at least a part of the heavy fraction originating from stage e) in which the heavy fraction and hydrogen are passed over a hydrotreatment catalyst under hydrotreatment conditions.
9. Process according to claim 8 in which the hydrotreatment stage is carried out at a temperature comprised between 300 and 500°C, a partial pressure of hydrogen comprised between 2 MPa and 25 MPa, an overall hourly space velocity (HSV) situated in a range from 0.1 h^-1 to 5 h^-1, a quantity of hydrogen mixed with the feedstock of 100 to 5000 Nm³/m³.
10. Process according to claim 8 or 9 in which a co-feedstock is introduced with the heavy fraction to the hydrotreatment stage f).
11. Process according to claim 10 in which the co-feedstock is selected from atmospheric residues, vacuum residues originating from direct distillation, deasphalted oils, aromatic extracts originating from lubricant base production chains, hydrocarbon-containing fractions or a mixture of hydrocarbon-containing fractions able to be selected from the products originating from a fluid catalytic cracking process: a light cycle oil (LCO), a heavy cycle oil (HCO), a decanted oil, or can come from distillation, gas oil fractions, in particular those obtained by atmospheric or vacuum distillation, such as for example vacuum gas oil.
12. Process according to one of the preceding claims in which the feedstock treated is selected from atmospheric residues, vacuum residues originating from direct distillation, crude oils, topped crude oils, deasphalted oils, deasphalting resins, asphalts or deasphalting pitches, residues originating from conversion processes, aromatic extracts originating from lubricant base production chains, bituminous sands or derivatives thereof, oil shales or derivatives thereof, alone or in a mixture.
13. Process according to one of the preceding claims in which the final boiling temperature of the feedstock is at least 540°C.
14. Process according to one of the preceding claims in which the feedstock contains at least 1 % C7 asphaltenes and at least 5 ppm of metals.
15. Process according to one of claims 8 to 14 in which the heavy fractions originating from stages d) and/or e) and/or f) are mixed with one or more fluxing bases selected from the group constituted by the light cycle oils of a catalytic cracking, the heavy cycle oils of a catalytic cracking, the residue of a catalytic cracking, a kerosene, a gas oil, a vacuum distillate and/or a decanted oil.

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