EP3018188A1 - Process for converting petroleum feedstocks comprising a stage of fixed-bed hydrotreatment, a stage of ebullating-bed hydrocracking, a stage of maturation and a stage of separation of the sediments for the production of fuel oils with a low sediment content - Google Patents

Abstract

The invention relates to a method for treating a hydrocarbon feedstock comprising the following steps: a) a step of hydrotreatment in a fixed bed, b) an optional step of separation of the effluent from step a) of hydrotreatment c) a step of hydrocracking at least part of the effluent from step a) or at least a portion of the heavy fraction resulting from step b), d) a separation step effluent from step c), e) a step of maturation of the heavy liquid fraction resulting from step d) of separation, f) a step of separating the sediments from the heavy liquid fraction resulting from the step e) ripening.

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. 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.

According to Annex VI of the MARPOL Convention, a ship may therefore use a sulfur-containing fuel oil if the ship is equipped with a flue gas treatment system that reduces emissions of sulfur oxides.

Methods for refining and converting heavy petroleum feedstocks comprising a first fixed bed hydrotreatment step and then a bubbling bed hydrocracking step have been described in the patent documents. FR 2764300 and EP 0665282 . EP 0665282 describes a hydrotreatment process of heavy oils with the aim of extending the life of the reactors. The process described in FR 2764300 describes a process for obtaining fuels (gasoline and diesel) having in particular a low sulfur content. The fillers treated in this process do not contain asphaltenes.

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. These processes, although known to be suitable for heavy loads loaded with impurities, however, produce hydrocarbon fractions comprising catalyst fines and sediments which must be removed to satisfy a product quality such as bunker fuel oil.

The sediments may be precipitated asphaltenes. Initially in the feed, the conversion 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%.

The applicant in his research has developed a new process incorporating a step of maturation and sediment separation downstream of a fixed bed hydrotreating step and a hydrocracking step. Surprisingly, it has been found that such a method makes it possible to obtain liquid hydrocarbon fractions having a low sediment content after aging, said fractions being advantageously wholly or partly used as fuel oil or as fuel oil base for the future. specifications, namely and a sediment content after aging less than or equal to 0.1% by weight

One of the objectives of the present invention is to propose a process for converting heavy petroleum feedstocks for the production of fuel oils and fuel bases. in particular bunker oil and bunker oil bases with a low sediment content after aging less than or equal to 0.1% by weight.

Another object of the present invention is to jointly produce, by the same method, atmospheric distillates (naphtha, kerosene, diesel), vacuum distillates and / or light gases (C1 to C4). 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.

Brief description of the figures

• The figure 1 represents a schematic view of the process according to the invention, showing a hydrotreatment zone, a zone for separating the effluent from the hydrotreatment zone, a hydrocracking zone and a zone for separating the effluent from the hydrotreatment zone. hydrocracking zone and a zone of ripening and separation of sediments.
• The figure 2 is a schematic view of the process according to the invention in a variant in which the separation zone of the effluent of the hydrotreatment zone is simplified.
• The figure 3 is a schematic view of the process without a zone of separation of the effluent from the hydrotreatment zone.

detailed description Load

The feedstock treated in the process according to the invention is preferably a hydrocarbon feed having an initial boiling point of at least 340 ° C and a final boiling point of at least 440 ° C. Preferably, its initial boiling point is at least 350 ° C., preferably at least 375 ° C., and its final boiling point is at least 450 ° C., preferably at least 450 ° C. at least 460 ° C, more preferably at least 540 ° C, and even more preferably at least 600 ° C.

The hydrocarbon feedstock according to the invention may be chosen from atmospheric residues, vacuum residues resulting from direct distillation, crude oils, crude head oils, deasphalting resins, asphalts or deasphalting pitches, process residues. conversion products, aromatic extracts from lubricant base production lines, oil sands or derivatives thereof, oil shales or their derivatives, source rock oils or their derivatives, whether alone or in combination. In the present invention, the fillers being treated are preferably atmospheric residues or vacuum residues, or mixtures of these residues.

The hydrocarbon feedstock treated in the process may contain, among other things, sulfur-containing impurities. The sulfur content may be at least 0.1% by weight, at least 0.5% by weight, preferably at least 1% by weight, more preferably at least 4% by weight, still more preferably at least 5% by weight. 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.

These charges can advantageously be used as they are. Alternatively, they can be diluted by co-charging. This co-charge may be a hydrocarbon fraction or a lighter hydrocarbon fraction mixture, which may preferably be chosen from the products resulting from a fluid catalytic cracking (FCC) process according to the English terminology. Saxon), 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 FCC residue, a gas oil fraction, especially a fraction obtained by atmospheric distillation or under vacuum, such as vacuum gas oil, or may come from another refining process. The co-charge may also advantageously be one or more cuts resulting from the liquefaction process of the coal or the 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.

The process according to the invention therefore comprises a first step a) of fixed bed hydrotreatment, optionally a step b) of separating the effluent from step a) of hydrotreatment into a light fraction and a heavy fraction, followed by a step c) bubbling bed hydrocracking of at least a portion of the effluent from step a) or at least a portion of the heavy fraction from step b), a step d) of separating the effluent from step c) to obtain at least one gaseous fraction and at least one heavy liquid fraction and finally a curing step e) and a separation step f) carried out on the heavy liquid fraction making it possible to obtain a liquid hydrocarbon fraction having a sediment content after aging less than or equal to 0.1% by weight.

The objective of hydrotreating is both to refine, that is to say to significantly reduce the content of metals, sulfur and other impurities, while improving the hydrogen to carbon ratio (H / C) and while transforming the hydrocarbon feed more or less partially into lighter cuts. The effluent obtained in the fixed bed hydrotreating step a) can then be sent to the bubbling bed hydrocracking step c) either directly or after being subjected to a light fraction separation step. Step c) allows a partial conversion of the feedstock to produce an effluent comprising in particular catalyst fines and sediments which must be removed to satisfy a product quality such as bunker oil. The process according to the invention is characterized by the fact that it comprises a maturation step e) and a separation step f) carried out under conditions making it possible to improve the sediment separation efficiency and thus to obtain fuel oils. or oil bases having a sediment content after aging less than or equal to 0.1% by weight.

One of the interests of the sequence of a hydrotreatment in a fixed bed and then a bubbling bed hydrocracking resides in the fact that the charge of the bubbling 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, the catalyst consumption in the bubbling bed hydrocracking reactor is greatly reduced compared to a process without prior fixed bed hydrotreatment.

Step a) Hydroprocessing

The filler according to the invention is subjected according to the process of the present invention to a fixed bed hydrotreating step a) in which the filler and hydrogen are contacted on a hydrotreatment catalyst.

Hydrotreatment, commonly known as HDT, is understood to mean the catalytic treatments with hydrogen supply making it possible to refine, that is to say, to reduce substantially the content of metals, sulfur and other impurities, hydrocarbon feedstocks, while improving the ratio hydrogen on the load and transforming the load more or less partially into lighter cuts. Hydrotreatment 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, hydroisomerization, hydrodealkylation, hydrocracking, hydro-deasphalting and Conradson carbon reduction.

According to a preferred variant, the hydrotreatment stage a) comprises a hydrodemetallation first stage (1) (HDM) carried out in one or more hydrodemetallation zones in fixed beds and a second hydrodesulphurization second stage (a2) (HDS). performed in one or more hydrodesulfurization zones in fixed beds. During said first step a1) of hydrodemetallation, the feedstock and hydrogen are brought into contact on a hydrodemetallization catalyst, under hydrodemetallation conditions, and then during said second hydrodesulfurization step a2), the effluent of the first hydrodemetallation step a1) is brought into contact with a hydrodesulphurization catalyst, in hydrodesulfurization conditions. This process, known as HYVAHL-FTM, is for example described in the patent US 5417846 .

The person skilled in the art easily understands that, in the hydrodemetallization step, hydrodemetallation reactions are carried out but also a part of the other hydrotreatment reactions and in particular hydrodesulfurization reactions. Similarly, in the hydrodesulphurization step, hydrodesulphurization reactions are carried out, but also part of the other hydrotreatment reactions and in particular hydrodemetallation reactions. One skilled in the art understands that the hydrodemetallization step begins where the hydrotreatment step begins, where the metal concentration is maximum. Those skilled in the art understand that the hydrodesulfurization step ends where the hydrotreating step ends, where sulfur removal is the most difficult. Between the hydrodemetallation step and the hydrodesulfurization step, the skilled person sometimes defines a transition zone in which all types of hydrotreatment reaction occur.

The hydrotreating step a) according to the invention is carried out under hydrotreatment conditions. It may advantageously be carried out at a temperature of between 300 ° C. and 500 ° C., preferably between 350 ° C. and 420 ° C. and under a hydrogen partial pressure of between 5 MPa and 35 MPa, preferably between MPa and 20 MPa. The temperature is usually adjusted according to the desired level of hydrotreatment and the duration of the targeted treatment. 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 divided by the total volume of the reactor, 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 feed, preferably between 200 Nm3 / m3 and 2000 Nm3 / m3, and more preferably between 300 Nm3 / m3 and 1500 Nm3 / m3. Step a) of hydrotreatment can be carried out industrially in one or more liquid downflow reactors.

The hydrotreatment catalysts used are preferably known catalysts. These may be 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, it is possible to use a catalyst comprising from 0.5% to 10% by weight of nickel, preferably from 1% to 5% by weight of nickel (expressed as nickel oxide NiO), and from 1% to 30% by weight of nickel. weight of molybdenum, preferably from 5% to 20% by weight of molybdenum (expressed as molybdenum oxide MoO3) 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. Advantageously, this support may contain other doping compounds, in particular oxides selected from the group consisting of 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. When phosphorus pentoxide P2O5 is present, its concentration is less than 10% by weight. When B2O5 boron trioxide is present, its concentration is less than 10% by weight. The alumina used may be a gamma (γ) or η (eta) alumina. This catalyst is most often in the form of extrudates. The total content of metal oxides of groups VIB and VIII may be from 5% to 40% by weight and in general from 7% to 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 between 20 and 1, and most often between 10 and 2.

In the case of a hydrotreating step including a hydrodemetallation (HDM) step and then a hydrodesulphurization step (HDS), specific catalysts adapted to each step are preferably used.

Catalysts that can be used in the hydrodemetallation step are, for example, indicated in the patent documents EP 0113297 , EP 0113284 , US 5221656 , US 5827421 , US 7119045 , US 5622616 and US 5089463 . HDM catalysts are preferably used in the reactive reactors.

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

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

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 b) optional separation

The step of separating the effluent from step a) of hydrotreatment is optional.

In the case where the step of separating the effluent from step a) of hydrotreatment is not implemented, at least part of the effluent from step a) of hydrotreatment is introduced in the section allowing the implementation of step c) bubbling bed hydrocracking without changing chemical composition and without significant pressure loss. "Significant loss of pressure" means a loss of pressure caused by a valve or expansion turbine, which could be estimated at a pressure loss of more than 10% of the total pressure. Those skilled in the art generally use these pressure losses or relaxations during the separation steps.

When the separation step is carried out on the effluent from step a) of hydrotreatment, this is optionally supplemented by further additional separation steps, making it possible to separate at least one light fraction and at least one less a heavy fraction.

By "light fraction" is meant a fraction in which at least 90% of the compounds have a boiling point below 350 ° C.

By "heavy fraction" is meant a fraction in which at least 90% of the compounds have a boiling point greater than or equal to 350 ° C. Preferably, the light fraction obtained during the separation step b) comprises a gaseous phase and at least a light fraction of hydrocarbons of the naphtha, kerosene and / or diesel type. The heavy fraction preferably comprises a vacuum distillate fraction and a vacuum residue fraction and / or an atmospheric residue fraction.

The separation step b) can be implemented by any method known to those skilled in the art. This method can be selected from high or low pressure separation, high or low pressure distillation, high or low pressure stripping, and combinations of these different methods that can operate at different pressures and temperatures.

According to a first embodiment of the present invention, the effluent from step a) hydrotreatment undergoes a step b) separation with decompression. According to this embodiment, the separation is preferably carried out in a fractionation section which may firstly comprise a high temperature high pressure separator (HPHT), and possibly a low temperature high pressure separator (HPBT), followed optionally afterwards. an atmospheric distillation section and / or a vacuum distillation section. The effluent of step a) can be sent to a fractionation section, generally in an HPHT separator making it possible to obtain a light fraction and a heavy fraction containing predominantly boiling compounds at at least 350 ° C. In general, the separation is preferably not made according to a precise cutting point, it is rather like a separation of instantaneous type (or flash according to the Anglo-Saxon terminology). The cutting point of the separation is advantageously between 200 and 400 ° C.

Preferably, said heavy fraction can then be fractionated by atmospheric distillation into at least one atmospheric distillate fraction, preferably containing at least a light fraction of naphtha, kerosene and / or diesel type hydrocarbons, and an atmospheric residue fraction. At least a portion of the atmospheric residue fraction can also be fractionated by vacuum distillation into a vacuum distillate fraction, preferably containing vacuum gas oil, and a vacuum residue fraction. At least a portion of the vacuum residue fraction and / or the atmospheric residue fraction are advantageously sent to the hydrocracking step c). Part of the vacuum residue may also be recycled in the hydrotreating step a).

According to a second embodiment, the effluent from step a) hydrotreatment undergoes a step b) separation without decompression. According to this embodiment, the effluent of the hydrotreatment step a) is sent to a fractionation section, generally in an HPHT separator, having a cutting point between 200 and 400 ° C. making it possible to obtain at least one light fraction and at least one heavy fraction. In general, the separation is preferably not made according to a precise cutting point, it is rather like a separation of the instantaneous type (or flash according to the English terminology). The heavy fraction can then be directly sent to the hydrocracking step c).

The light fraction may undergo other separation steps. Advantageously, it may be subjected to atmospheric distillation to obtain a gaseous fraction, at least a light fraction of liquid hydrocarbons of the naphtha, kerosene and / or diesel type and a vacuum distillate fraction, the last fraction possibly being at least part sent in step c) hydrocracking. Another part of the vacuum distillate can be used as a fluxing agent for a fuel oil. Another part of the vacuum distillate can be upgraded by being subjected to a hydrocracking step and / or catalytic cracking in a fluidized bed.

No-decompression separation provides better thermal integration and saves energy and equipment. In addition, this embodiment has technical and economic advantages since it is not necessary to increase the flow pressure after separation before the subsequent hydrocracking step. Intermediate fractionation without decompression being simpler than fractionation with decompression, the investment cost is therefore advantageously reduced.

The gaseous fractions resulting from the separation step preferably undergo a purification treatment to recover the hydrogen and recycle it to the hydrotreatment and / or hydrocracking reactors. The presence of the separation step between the hydrotreatment step a) and the hydrocracking step c) advantageously makes it possible to have two independent hydrogen circuits, one connected to the hydrotreatment, the hydrocracking, and which, if necessary, can be connected to each other. The addition of hydrogen can be done at the hydrotreatment section or at the level of the hydrocracking section or at both. The recycle hydrogen can supply the hydrotreatment section or the hydrocracking section or both. A compressor may possibly be common to both hydrogen circuits. The fact of being able to connect the two hydrogen circuits makes it possible to optimize the management of hydrogen and to limit the investments in terms of compressors and / or purification units of the gaseous effluents. The various embodiments of the hydrogen management that can be used in the present invention are described in the patent application. FR 2957607 .

The light fraction obtained at the end of the separation step b), which comprises hydrocarbons of the naphtha, kerosene and / or diesel or other type, in particular LPG and vacuum gas oil, can be recovered according to the methods which are well known in the art. the skilled person. The products obtained can be incorporated into fuel formulations (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, for example hydrotreatment, hydrocracking, alkylation, isomerization, reforming. catalytic, catalytic cracking or thermal, to bring them separately or in mixture with the required specifications which may relate to the sulfur content, the smoke point, the octane number, cetane, and others.

Step c) bubbling bed hydrocracking

At least a portion of the effluent from step a) of hydrotreatment or at least a portion of the heavy fraction from step b) is sent according to the process of the present invention in a step c) of hydrocracking which is carried out in at least one reactor, advantageously two reactors, containing at least one catalyst supported in a bubbling bed. Said reactor can operate at an upward flow of liquid and gas. The main objective of hydrocracking is to convert the heavy hydrocarbon feedstock into lighter cuts while partially refining it.

According to one embodiment of the present invention, part of the initial hydrocarbon feedstock can be injected directly into the bubbling bed hydrocracking section c), mixed with the effluent of the hydrotreatment section a) in fixed bed or the heavy fraction from step b), without this portion of the hydrocarbon feedstock being treated in the hydrotreatment section a) in a fixed bed. This embodiment can be likened to a partial short circuit of the hydrotreatment section a) in a fixed bed.

According to one variant, a co-charge may be introduced at the inlet of the hydrocracking section c) in a bubbling bed with the effluent of the hydrotreatment section a) in fixed bed or the heavy fraction resulting from step b) . 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 fluid-bed catalytic cracking process, in particular a light cutting oil (LCO), a heavy cutting oil (HCO), a decanted oil, or possibly derived from distillation, the gas oil fractions including those obtained by atmospheric or vacuum distillation, such as, for example, vacuum gas oil. According to another variant and in the case where the hydrocracking section has several bubbling bed reactors, this co-charge may be partially or totally injected into one of the reactors downstream of the first reactor.

The hydrogen necessary for the hydrocracking reaction may already be present in sufficient quantity in the effluent resulting from the hydrotreatment stage a) injected at the inlet of the hydrocracking section c) in a bubbling bed. However, it is preferable to provide an additional supply of hydrogen at the inlet of the hydrocracking section c). In the case where the hydrocracking section has several bubbling bed reactors, hydrogen can be injected at the inlet of each reactor. The injected hydrogen may be a make-up stream and / or a recycle stream.

Bubbling bed technology is well known to those skilled in the art. Only the main operating conditions will be described here. Bubbling bed technologies conventionally use supported catalysts in the form of extrudates whose diameter is generally of the order of 1 millimeter or less. The catalysts remain inside the reactors and are not evacuated with the products, except during the makeup and catalyst withdrawal phases necessary to maintain the catalytic activity. The temperature levels can be 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, working at constant operating conditions advantageously 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. Because of the attrition of the catalysts in the reactors, the products leaving the reactors may contain fine particles of catalyst.

The conditions of the bubbling bed hydrocracking step c) can be conventional bubbling bed hydrocracking conditions of a feedstock. hydrocarbon. It can be operated under an absolute pressure of between 2.5 MPa and 35 MPa, preferably between 5 MPa and 25 MPa, more preferably between 6 MPa and 20 MPa, and even more preferably between 11 MPa and 20 MPa at a temperature between 330 ° C and 550 ° C, preferably between 350 ° C and 500 ° C. The space velocity (WH) and the hydrogen partial pressure are parameters that are set according to the characteristics of the product to be treated and the desired conversion. The WH is generally in a range from 0.1 h ^-1 to 10 h ^-1 , preferably from 0.2 h ^-1 to 5 h ^-1 and more preferably from 0.2 h ^-1 to 1 h ^-1 . The amount of hydrogen mixed with the feedstock is usually from 50 to 5000 normal cubic meters (Nm3) per cubic meter (m3) of liquid feed, most often from 100 Nm3 / m3 to 1500 Nm3 / m3 and preferably 200 Nm3 / m3 at 1200 Nm3 / m3.

It is possible to use a conventional granular hydrocracking catalyst comprising, on an amorphous support, at least one metal or metal compound having a hydrodehydrogenating 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 MoO3) 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 P2O5 is present, its concentration is usually less than 20% by weight and most often less than 10% by weight. When B2O3 boron trioxide is present, its concentration is usually less than 10% by weight. The alumina used is usually an γ (gamma) or η (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 spent catalyst may be partly replaced by fresh catalyst, generally by withdrawing from the bottom of the reactor and introducing the fresh or new catalyst at the top of the reactor at a 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).

The hydrocracking step c) according to the process of the invention can be carried out under the conditions of the H-OIL® process as described, for example, in the patent US 6270654 .

The bubbling bed hydrocracking can be carried out in a single reactor or in several reactors, preferably two, arranged in series. The fact of using at least two bubbling bed reactors in series makes it possible to obtain products of better quality and with better performance. In addition, the hydrocracking into two reactors makes it possible to have an improved operability with regard to the flexibility of the conditions operating and catalytic system. Preferably, the temperature of the second bubbling bed reactor is at least 5 ° C higher than that of the first bubbling bed reactor. The pressure of the second reactor may be 0.1 MPa 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 operating conditions in terms of temperature in the two hydrocracking reactors are selected to be able to control the hydrogenation and the conversion of the feedstock into the desired products in each reactor.

In the case where the hydrocracking step c) is carried out in two substeps c1) and c2) in two reactors arranged in series, the effluent obtained at the end of the first substep c1) can optionally be subjected to a separation step of the light fraction and the heavy fraction, and at least a portion, preferably all, of said heavy fraction can be treated in the second hydrocracking sub-step c2). This separation is advantageously made in an inter-floor separator, as described for example in the patent US 6270654 , and in particular makes it possible to avoid over cracking 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 reactor of the first sub-stage (b1) of hydrocracking, operating at a lower temperature, directly to the reactor of the second substep (b2), operating at higher temperature, or to transfer all or part of the used catalyst withdrawn from the reactor of the second substep (b2) directly to the reactor of the first substep (b1). This cascade system is for example described in the patent US 4816841 .

The hydrocracking stage can also be done with several reactors in parallel (generally two) in the case of large capacity. The hydrocracking step may thus comprise several stages in series, possibly separated from an inter-stage separator, each stage being constituted by one or more reactors in parallel.

Step d) separating the hydrocracking effluent

The process according to the invention may furthermore comprise a step d) of separation which makes it possible to obtain at least one gaseous fraction and at least one heavy liquid fraction.

The effluent obtained at the end of the hydrocracking step c) 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 effluent by means of separation devices well known to those skilled in the art, in particular with the aid of one or more separator tanks that can operate at different pressures and temperatures, possibly associated with steam or hydrogen stripping means and one or more distillation columns. The effluent obtained at the end of the hydrocracking step c) is advantageously separated in at least one separator flask into at least one gaseous fraction and at least one heavy liquid fraction. These separators may for example be high temperature high pressure separators (HPHT) and / or high temperature low pressure separators (HPBT).

After a 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 type system, or a plurality of such 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 hydrocracking step c) and / or at different locations during step c) hydrocracking.

The separation step d) may also comprise atmospheric distillation and / or vacuum distillation. Advantageously, the separation step d) further comprises at least one atmospheric distillation, in which the fraction (s) liquid hydrocarbon (s) obtained after separation is (are) fractionated 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 d) 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. Preferably, the separation step d) comprises, first of all, an atmospheric distillation, in which the liquid hydrocarbon fraction (s) obtained after separation is (are) fractionated (s). ) by atmospheric distillation into 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 minus a fraction residue under vacuum. The vacuum distillate fraction typically contains vacuum gas oil fractions.

At least a portion of the vacuum residue fraction can be recycled to the hydrocracking step c).

Step e) : Maturation of the sediments

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

Depending on the hydrocracking conditions, the sediment content in the heavy liquid 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 40 or 50%, cause the formation of existing sediments and potential sediments.

In order to obtain a fuel oil or a fuel base that meets the recommendations for a sediment content after aging (IP390) of less than or equal to 0.1%, the process according to the invention comprises a maturation stage making it possible to improve the sediment separation efficiency and thus to obtain stable oil or fuel bases, 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 of less than 20 MPa, preferably less than 10 MPa, more preferably less than 3 MPa and even more preferably less than 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 e) of maturation of the heavy liquid fraction resulting from step d) is carried out in the presence of an inert gas and / or an oxidizing gas.

The aging step e) can be 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 oxidizing gas 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 liquid fraction resulting from stage d) before the stage of maturation then separation of this gas after maturation so as to obtain a liquid fraction at the end of the stage e) 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 maturation step e), for example by means of bubbling (injection of gas from below) into a stirred tank which allows to promote gas / liquid contact.

At the end of the maturation step e), at least one hydrocarbon fraction with an enriched content of existing sediments is obtained which is sent to the sediment separation step f).

Step f): Separation of sediments

The method according to the invention further comprises a step f) of separating sediments and catalyst residues to obtain a liquid hydrocarbon fraction having a sediment content after aging less than or equal to 0.1% by weight.

The heavy liquid fraction obtained at the end of the maturation step e) contains precipitated asphaltene-type organic sediments which result from the hydrocracking and maturation conditions. This heavy fraction may also contain fines catalysts resulting from the attrition of extruded type catalysts in the implementation of hydrocracking reactor.

Thus, at least a part of the heavy liquid fraction resulting from the maturation stage e) 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 separation membrane, 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 f) 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 liquid fraction resulting from stage f) with a reduced sediment content may 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 liquid fraction is mixed with one or more fluxing bases selected from the group consisting of catalytically cracked light cutting oils, catalytic cracked heavy cutting oils, catalytic cracking residue, a kerosene, a gas oil, a vacuum distillate and / or a decanted oil.

fluxing

The liquid hydrocarbon fractions may, at least in part, advantageously be used as fuel oil bases or as fuel oil, especially as a bunker oil base or as a bunker oil with a sediment content after aging less than or equal to 0.1% by weight .

By "fuel oil" is meant in the invention a hydrocarbon fraction that can be used as a fuel. By "oil base" is meant in the invention a hydrocarbon fraction which, mixed with other bases, is a fuel oil.

To obtain a fuel oil, the liquid hydrocarbon fractions from step f) may be mixed with one or more fluxing bases selected from the group consisting of light-cutting oils of a catalytic cracking, heavy cutting oils of a catalytic cracking, the residue of a catalytic cracking, a kerosene, a gas oil, a vacuum distillate and / or a decanted oil. Preferably, kerosene, gas oil and / or vacuum distillate produced in the process of the invention will be used.

Detailed description of the figures

The following figures describe examples of implementation of the invention without limiting the scope thereof.

The figure 1 represents a process according to the invention with separation of the effluent from the hydrotreating zone with decompression. 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.

• une première étape (étape i) au cours de laquelle la charge traverse successivement le réacteur Ra, puis le réacteur Rb,
• une deuxième étape (étape ii) au cours de laquelle la charge traverse uniquement le réacteur Rb, le réacteur Ra étant court-circuité pour régénération et/ou remplacement du catalyseur,
• une troisième étape (étape iii) au cours de laquelle la charge traverse successivement le réacteur Rb, puis le réacteur Ra,
• une quatrième étape (étape iv) au cours de laquelle la charge traverse uniquement le réacteur Ra, le réacteur Rb étant court-circuité pour régénération et/ou remplacement du catalyseur. Le cycle peut ensuite recommencer.

In the figure 1 the charge (10), preheated in the chamber (12), mixed with recycled hydrogen (14) and makeup hydrogen (24) preheated in the chamber (16), is introduced by the conduct (18) in 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) during which the feed 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 charge passes successively through the reactor Rb and then the reactor Ra,
• a fourth step (step iv) in 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.

The effluent leaving the at least one guard reactor (Ra, Rb) is optionally re-mixed with hydrogen arriving via line (65) in an HDM reactor (32) containing a fixed bed of 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 can be sent via line (42) into a high temperature high pressure separator (HPHT) (44) from which a gaseous fraction (46) and a liquid fraction (48) are recovered. ). The gaseous fraction (46) is sent, generally via an exchanger (not shown) or an air cooler (50) for cooling to a low temperature high pressure separator (HPBT) (52) from which a gaseous fraction (54) containing gases (H2, H2S, NH3, C1-C4 hydrocarbons, ...) and a liquid fraction (56). The gaseous fraction (54) from the low temperature high pressure separator (HPBT) (52) can be treated in a hydrogen purification unit (58) from which hydrogen (60) is recovered for recycling via the compressor (62) and the line (65) to the reactors (32) and / or (38) or via the line (14) to the permutable reactors (Ra, Rb). The liquid fraction (56) from the low temperature high pressure separator (HPBT) (52) is expanded in the device (68) and sent to the fractionation system (70). The liquid fraction (48) from the high temperature high pressure separator (HPHT) (44) is advantageously expanded in the device (72) and then sent to the fractionation system (70). Fractions (56) and (48) can be sent together, after expansion, to the fractionation (70).

The fractionation system (70) advantageously comprises an atmospheric distillation system for producing a gaseous effluent (74), at least one so-called light fraction (76) and containing in particular naphtha, kerosene and diesel and an atmospheric residue fraction (78). ).

Part of the atmospheric residue fraction can be sent via the line (80) into the hydrocracking reactors (98, 102). All or part of the atmospheric residue fraction (78) is sent to a vacuum distillation column (82) to recover a fraction (84) containing the vacuum residue and a vacuum distillate fraction (86) containing vacuum gas oil.

The vacuum residue fraction (84), optionally mixed with a portion of the atmospheric residue fraction (80) and / or with a portion of the vacuum distillate fraction (86), is mixed with optionally recycled hydrogen (88). supplemented with makeup hydrogen (90) preheated in the furnace (91). It optionally passes through an oven (92). Optionally, a co-charge (94) may be introduced.

The heavy fraction is then introduced via the line (96) in the hydrocracking step at the bottom of the first bubbling bed reactor operating at an upflow of liquid and gas and containing a supported hydrocracking catalyst. 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 bubbling bed operating with an upward flow of liquid and gas containing a hydrocracking catalyst of the supported type.

The operating conditions, in particular 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 heavy liquid fraction (140) are recovered.

The gaseous fraction (138) is sent generally via an exchanger (not shown) or a dry cooler (142) for cooling to a low temperature high pressure separator (HPBT) (144) from which a gaseous fraction (146) containing the gaseous fraction (146) is recovered. gas (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 advantageously 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 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 (not shown). ), and a liquid phase which is fed to the fractionation section (172).

The heavy 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 (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 into the capacity in the case of a tank agitated heated 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 curing devices (207) and (215) can operate in the presence of a gas, in particular an inert or oxidizing gas, or a mixture of 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 stage of maturation and separation of the sediments and catalyst residues on a fraction resulting from the step of separating the hydrocracking effluent, for example on a section heavy output 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 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-sulfur and low-sediment bunker fuels. Part of the streams (188) and / or (212) and / or (219), before or after the sediment ripening and separation step, can be recycled via line (190) to the hydrocracking step 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 type (212) or vacuum residue type (219) cutoff upstream of the hydrotreatment or hydrocracking may make it possible to increase the overall conversion.

The figure 2 represents another process according to the invention with separation of the effluent from the zone of hydrotreatment without decompression. It will be described below essentially only the differences between the process according to the figure 2 and the method according to figure 1 the hydrotreating, hydrocracking and separation stages after hydrocracking (and their reference signs) being moreover strictly identical.

The effluent treated in the hydrotreatment reactors is sent via line (42) into a high temperature high pressure separator (HPHT) (44) from which a lighter fraction (46) and a residual fraction (48) are recovered. .

The residual fraction (48) is sent directly after a possible passage through an oven (92) in the hydrocracking section.

The lighter fraction (46) is sent, generally via an exchanger (not shown) or an air cooler (50) for cooling to a low temperature high pressure separator (HPBT) (52) from which a gaseous fraction is recovered (54). containing the gases (H2, H2S, NH3, C1-C4 hydrocarbons ...) and a liquid fraction (56).

The gaseous fraction (54) of the low temperature high pressure separator (HPBT) (52) is treated in the hydrogen purification unit (58) from which hydrogen (60) is recovered for recycling via the compressor. (154) and lines (64) and (156) to the hydrotreatment section and / or the hydrocracking section.

Gases containing undesirable nitrogen, sulfur and oxygen compounds are advantageously removed from the plant (stream (66)). In this configuration, a single compressor (154) is used to supply all the reactors requiring hydrogen.

The liquid fraction (56) from the low temperature high pressure separator (HPBT) (52) is expanded in the device (68) and sent to the fractionation system (70).

The fractionation system (70) comprises an atmospheric distillation system for producing a gaseous effluent (74), at least a so-called light fraction (76) and containing in particular naphtha, kerosene and diesel and an atmospheric residue fraction (195). .

Part of the atmospheric residue fraction can be sent, by means of a pump, not represented, via the line (195) in the hydrocracking reactors (98, 102), whereas another part of the atmospheric residue fraction ( 194) can be sent to another process (hydrocracking or FCC or hydrotreatment).

A variant not shown but close to the diagram of the figure 2 may consist of not using a fractionation system (70) nor to relax the liquid fraction (56) from the cold separator (52). The liquid fraction (56) is then sent to the hydrocracking section optionally by means of a pump mixed with the heavy fraction (48) issuing from the separator (44).

The figure 3 represents another process according to the invention without a step of separation of the hydrotreatment effluent. It will be described below essentially only the differences between the process according to the figure 3 and the processes according to figures 1 and 2 the hydrotreatment, hydrocracking and separation stages after hydrocracking (and their reference signs) being moreover strictly identical. In the embodiment without the hydrotreatment effluent separation step, the effluent (42) of the fixed bed hydrotreatment reactor (38) is injected without separation and without decompression into the hydrocracking reactor (98). , via optional thermal equipment (43), (92) for adjusting the inlet temperature of the hydrocracking reactor. Upon separation of the effluent from the hydrocracking section (134), a hydrogen-rich gas is recovered and recycled to the hydrotreating section and the hydrocracking section.

EXAMPLES COMPARATIVE EXAMPLE AND ACCORDING TO THE INVENTION

The following example illustrates the invention without limiting its scope. A vacuum residue (RSV Ural) containing 87.0% by weight of compounds boiling at a temperature above 520 ° C, having a density of 9.5 ° API and a sulfur content of 2.72% by weight was treated. weight.

The feedstock was subjected to a hydrotreatment step including two permutable reactors. The operating conditions are given in Table 1. <u> Table 1: Operating conditions fixed bed step of hydrotreatment </ u> HDM and HDS catalysts NiMo on alumina Temperature (° C) 370 H2 partial pressure (MPa) 15 VVH (h-1, Sm3 / h fresh load / m3 fixed bed catalyst) 0.18 H2 / HC inlet section fixed bed excluding H2 consumption (Nm3 / m3 fresh load) 1000

The effluent from the hydrotreatment is then subjected to a separation step making it possible to recover a light fraction (gas) and a heavy fraction containing a majority of compounds boiling at more than 350 ° C (350 ° C + fraction).

The heavy fraction (350 ° C + fraction) is then treated in a hydrocracking step comprising two successive bubbling bed reactors with two sets of temperatures.

The operating conditions of the hydrocracking step are given in Table 2. <u> Table 2: Operating conditions of the hydrocracking section </ u> 2 bubbling beds 2 bubbling beds catalysts NiMo on alumina NiMo on alumina Temperature R1 (° C) 418 423 Temperature R2 (° C) 428 431 H2 partial pressure (MPa) 13.5 13.5 VVH "reactors" (h-1, Sm3 / h fresh load / m3 of reactors) 0.3 0.3 WH "bubbling bed catalysts" (h-1, Sm3 / h fresh load / m3 bubbling bed catalysts) 0.6 0.6 Slurry catalyst concentration (ppm of precursor in the slurry feedstock) - - H2 / HC entry hydrocracking section excluding H2 consumption (Nm3 / m3 fresh load) 600 600

• une étape de séparation des sédiments et résidus de catalyseurs comportant un filtre poreux métallique de marque Pall® (non-conforme, selon l'art antérieur),
• une étape de maturation réalisée pendant 4h à 150°C et de séparation des sédiments et résidus de catalyseurs comportant un filtre (conforme à l'invention).

The effluents of the hydrocracking step were then subjected to a separation step for separating a gaseous fraction and a heavy liquid fraction by means of separators and atmospheric and vacuum distillation columns. In addition, prior to the vacuum distillation step, the heavy liquid fraction undergoes a treatment according to 2 variants:

• a step of separation of sediments and catalyst residues comprising a Pall® brand porous metal filter (non-compliant, according to the prior art),
• a maturation step carried out for 4 hours at 150 ° C. and separation of the sediments and catalyst residues comprising a filter (according to the invention).

The yields and the sulfur contents of each fraction obtained in the effluents leaving the global chains are given in Table 3 below: <u> Table 3: Yield and Sulfur Content of the Hydrocracking Section Effluent (% w / w) </ u> Hydrotreatment fixed bed + separation + Hydrocracking 2 bubbling beds (418/428 ° C) Hydrotreatment fixed bed + separation + Hydrocracking 2 bubbling beds (423/431 ° C) products Yield (% wt) S (% wt) Yield (% wt) S (% wt) NH3 0.7 0 0.7 0 H2S 2.7 94.12 2.7 94.12 C1-C4 (gas) 3.8 0 4.0 0 Naphtha (PI - 150 ° C) 8.0 0.02 9.3 0.02 Diesel (150 ° C - 350 ° C) 22.7 0.05 24.6 0.05 Vacuum distillate (350 ° C - 520 ° C) 29.5 0.26 31.5 0.28 Vacuum residue (520 ° C +) 34.3 0.43 29.3 0.47

The operating conditions of the hydrocracking step coupled with the different treatment variants (separation of sediments with or without a maturation stage) of the heavy liquid fraction resulting from atmospheric distillation have an impact on the stability of the effluents obtained. This is illustrated by the levels in post-aging sediment measured in atmospheric residues (350 ° C + cut) after the sediment separation step.

The performances of the three treatment schemes are summarized in Table 4 below: <u> Table 4: Summary of Performance </ u> Hydrotreatment fixed bed + separation + Hydrocracking 2 bubbling beds (418/428 ° C) Hydrotreatment fixed bed + separation + Hydrocracking 2 bubbling beds (423/431 ° C) H2 consumption (% w / w) 1.7 1.8 Hydrodesulfurization rate (%) 91 91 Conversion rate (%) 61 66 Maturation No No Yes Separation of sediments Yes Yes Yes Sediment content after aging (IP390) in the 350 ° C + cut from sediment separation <0.1 0.4 <0.1

The stage of maturation prior to the separation of the sediments makes it possible to form all the potential sediments and thus allow their effective separation. Without maturation, beyond a certain conversion level that leads to many potential sediments, the sediment separation step is not efficient enough for the sediment content after aging (IP390) to be lower than 0.1% by weight, the maximum level required for bunker fuels.

Claims (8)

A process for treating 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 temperature of boiling at least 440 ° C to obtain a liquid hydrocarbon fraction having a sediment content after aging less than or equal to 0.1% by weight, said process comprising the following steps: a) a fixed bed hydrotreatment step, wherein the hydrocarbon feedstock and hydrogen are contacted on a hydrotreatment catalyst, b) an optional step of separating the effluent from step a) of hydrotreating into at least a light hydrocarbon fraction containing fuels bases and a heavy fraction containing compounds boiling at least 350 ° C, c) a step of hydrocracking at least a portion of the effluent from step a) or at least a portion of the heavy fraction resulting from step b), in at least one reactor containing a catalyst supported in bubbling bed, d) a step of separating the effluent from step c) to obtain at least one gaseous fraction and at least one heavy liquid fraction, e) a step of maturation of the heavy liquid fraction resulting from the separation step d) 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 between 50 and 350 ° C, and a pressure below 20 MPa, f) a sediment separation step of the heavy liquid fraction from the maturation step e) to obtain a liquid hydrocarbon fraction having a sediment content after aging less than or equal to 0.1% by weight. A process according to claim 1 wherein the hydrotreatment step a) comprises a first hydrodemetallization step a1) carried out in one or more fixed bed hydrodemetallation zones and a second hydrodesulfurization second step a2) carried out in one or more several hydrodesulfurization zones in fixed beds. Process according to either of Claims 1 and 2, in which the hydrotreatment step a) is carried out at a temperature of between 300 ° C. and 500 ° C. under a hydrogen partial pressure of between MPa and 35 MPa, with a space velocity of the hydrocarbon feedstock in a range of 0.1 hr-1 to 5 hr-1, and the amount of hydrogen blended with the feed is between 100 Nm3 / m3 and 5000 Nm3 / m3. Process according to any one of claims 1 to 3, in which the hydrocracking step c) is carried out under an absolute pressure of between 5 MPa and 35 MPa, at a temperature of between 330 ° C. and 550 ° C., with a space velocity in a range of 0.1 h ^-1 to 10 h ^-1 , and the amount of hydrogen mixed with the feed is 50 Nm 3 / m3 to 5000 Nm 3 / m3. Method according to one of the preceding claims wherein the step of maturation of the heavy liquid fraction from step d) is carried out in the presence of an inert gas and / or an oxidizing gas. Process according to one of the preceding claims in the separation step f) is carried out by means of at least one separation means chosen from a filter, a separation membrane, a bed of organic or inorganic type filtering solids, a electrostatic precipitation, a centrifugation system, decantation, auger withdrawal. Process according to one of the preceding claims, in which the treated filler is chosen from atmospheric residues, vacuum residues resulting from direct distillation, crude oils, crude head oils, deasphalted oils, deasphalting resins, asphalts or deasphalting pitches, 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 in combination. Method according to one of the preceding claims wherein the liquid hydrocarbon fractions from step f) are mixed with one or more fluxing bases selected from the group consisting of light cutting oils of a catalytic cracking, cutting oils catalytically cracked, the residue of a catalytic cracking, a kerosene, a gas oil, a vacuum distillate and / or a decanted oil.

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