EP1505142A1 - Process for upgrading of heavy feeds by deasphalting and hydrocracking in ebullated bed. - Google Patents

Abstract

Treatment of a hydrocarbon charge in which at least 95% comprises compounds of boiling points of at least 340[deg]C by stages of deasphalting, cracking, fractionation and further cracking of a residue, to produce petrols, kerosenes and gasoils. The process comprises stages of (1) (a) contact of the charge with a solvent to obtain a deasphalted effluent having an asphaltene content(insolubles in n-heptane) less than 3000 ppm wt.; (2) (b) cracking of the deasphalted effluent in the presence of hydrogen and a hydrocracking catalyst in a fluidized bed reactor, converting at least 50% wt. of the effluent of the fraction boiling above 500[deg]C into compounds of boiling points below 500[deg]C; (3) (c) fractionation of the effluent from (b) and recovery of petrols, kerosene, gasoils and a primary residue; (4) and(d) catalytic cracking of the residue to obtain an effluent comprising petrols, kerosene, gasoils and a second residue.

Description

The field of the present invention is that of the refining of the slices oil. It relates in particular to the field of heavy loads such as residues from atmospheric distillation or vacuum distillation.

Given the growing demand for fuels, gasoline and diesel, and the decline in consumption of heavy fuels, it becomes more and more important to be able to convert to a very high level the bottom of the barrel.

This is particularly true for some countries where local production in oil consists mainly of so-called heavy crude, such as, for example, the Athabasca crude in Canada, Morichal in Venezuela, containing very few distillates light. Indeed, these heavy crudes contain about 80% by weight of residue under empty. These crudes are also characterized by a low API density, less than 12.

In addition, heavy loads such as atmospheric residues and Vacuum residues contain significant amounts of metals, sediments and asphaltenes. When these charges are used in conversion processes thermally, such as visbreaking, the impurities of these charges lead to rapidly coking and capping of the capacities by flocculation and sedimentation. When these same charges are used in conversion processes catalytic fixed bed, the presence of impurities requires the use of guard bed to protect the refining catalysts and prevent very rapid deactivation, thus increasing the volume of the reactors of these units.

In addition, in fixed bed conversion units, the conversion of the load is limited by thermal levels which are lower than in the conversion units in bubbling bed. When these charges are used in bubbling bed catalytic conversion processes, the presence of of these impurities leads to the increase of the catalyst replacement rate.

French patent FR 2 803 596 describes a process for converting distillates comprising a boiling bed hydroconversion step, a separation step in which a light fraction and a heavy fraction are obtained, and a step of catalytic cracking of the heavy fraction. Such a process can lead to conversion levels, but its implementation is not generally envisaged only for fillers with a final boiling point below 600 ° C. In addition, the described in this patent is, a priori, not suitable for the treatment of a atmospheric residue or a vacuum residue from a heavy crude.

It has been found a method to overcome the disadvantages mentioned above and also allowing to obtain high yields of species, kerosene and gas oils from residues from distillation atmospheric or vacuum distillation of a heavy crude. This process allows also to obtain products of good quality not requiring post-processing or requiring only moderate post-treatments.

a) on met en contact la charge avec un solvant de manière à obtenir un effluent désasphalté ayant une teneur en asphaltènes (insolubles dans le n-heptane selon la norme NF-T-60-115) inférieure à 3000 ppm poids,

b) on craque l'effluent désasphalté en présence d'hydrogène et d'un catalyseur d'hydrocraquage, dans un réacteur à lit bouillonnant, de manière à convertir au moins 50 % en poids de la fraction de l'effluent désasphalté bouillant au dessus de 500°C en composés ayant un point d'ébullition inférieur à 500°C,

c) on fractionne l'effluent de l'étape b) pour récupérer des essences, du kérosène, des gazoles et un premier résidu, et

d) on craque catalytiquement au moins une partie de ce premier résidu de manière à obtenir un effluent comprenant des essences, du kérosène, des gazoles et un second résidu.

The present invention therefore relates to a process for treating a hydrocarbon feedstock of which at least 95% by weight consist of compounds having a boiling point of at least 340 ° C., characterized in that it comprises the following steps, in which:

a) the charge is brought into contact with a solvent so as to obtain a deasphalted effluent having a content of asphaltenes (insoluble in n-heptane according to standard NF-T-60-115) of less than 3000 ppm by weight,

b) the deasphalted effluent in the presence of hydrogen and a hydrocracking catalyst is cracked in a bubbling bed reactor so as to convert at least 50% by weight of the fraction of the deasphalted effluent boiling above 500 ° C in compounds having a boiling point below 500 ° C,

c) the effluent from step b) is fractionated to recover gasolines, kerosene, gas oils and a first residue, and

d) at least a portion of this first residue is catalytically cracked so as to obtain an effluent comprising gasolines, kerosene, gas oils and a second residue.

An advantage of the invention is to provide a method for obtaining a better recovery of heavy loads such as atmospheric residues, vacuum residues obtained from any crude oil, particularly from heavy crude oils. These crude oils generally have a API density less than 12.

Another advantage of the invention is to provide a method for targeting a high overall yield of gasoline, kerosene and gas oils.

Another advantage of the invention is to provide a method for to obtain gasolines, kerosene and gas oils with excellent qualities and to limit the number or severity of post-treatments.

For a better understanding, two non-limiting modes of the process of the invention are illustrated by figures.

FIG. 1 represents, by way of example, an embodiment of the method according to the invention chaining a deasphalting step, a step ebullating hydroconversion, a fractionation step by distillation atmospheric and an FCC-type catalytic cracking step.

Figure 2 represents, by way of example, a scheme similar to that of the Figure 1, but wherein the fractionation step comprises a distillation atmospheric and vacuum distillation, the vacuum distillate being sent to a hydrocracking step.

The fillers that can be treated by the process of the invention are hydrocarbons of which at least 95% by weight are composed of compounds having a boiling point of at least 340 ° C and up to 700 ° C or higher, by between 500 ° C and 700 ° C.

The hydrocarbon feedstock has a final boiling point, preferably greater than 600 ° C, more preferably greater than 650 ° C, still more preferred above 700 ° C.

These charges may be atmospheric residues and residues empty. For example, these charges may be residues from distillations processes or conversion processes such as coking, Fixed bed hydroconversion, such as the HYVAHL process or bed processes bubbling like the H-Oil process. Charges can be formed by mixture of these fractions in any proportion or by dilution into petroleum fractions having a boiling point of less than 360 ° C.

The invention is particularly interesting for certain residues of heavy crudes, ie crudes containing few distillates. Typically raw Athabasca and Morichal contain 80% vacuum residues. Their API density is usually close to 10. These heavy crudes contain, compared to others gross, many more impurities such as, for example, metals (nickel, vanadium, silicon, etc.), a high Conradson Carbon, asphaltenes, sulfur and nitrogen.

Thus, according to a preferred embodiment, the hydrocarbon feedstock comprises essentially atmospheric residues, of which at least 95% by weight are consisting of compounds having a boiling point of at least 600 ° C, and vacuum residues of heavy crudes, of which at least 95% by weight consists of compounds having a boiling point of at least 650 ° C.

During step a) of the process of the invention, the charge is brought into contact with a solvent to obtain a desalphalted effluent. This operation is often qualified solvent deasphalting. It makes it possible to extract a large part of asphaltenes and reduce the metal content. During this deasphalting, these The last elements are concentrated in an effluent called asphalt. The deasphalted effluent, often referred to as deasphalted oil, has a reduced to asphaltenes and metals.

One of the objectives of the deasphalting step is, on the one hand, to maximize the quantity of deasphalted oil and, on the other hand, to maintain or even minimize the asphaltenes content. This asphaltene content is generally determined by term of asphaltene content insoluble in heptane, ie measured according to a method described in standard NF-T 60-115 of January 2002.

According to the invention, the asphaltenes content of the unphased effluent is less than 3000 ppm weight.

Preferably, the asphaltene content of the deasphalted effluent is less than 1000 ppm by weight, more preferably less than 500 ppm by weight.

Below an asphaltene content of 500 ppm by weight, the method of NF-T 60-115 is no longer sufficient to measure this content. The applicant has developed an analytical method, covering the analysis quantification of asphaltenes from direct distillation products and heavy products from deasphalting residues. This method can be used for Asphaltene concentrations of less than 3000 ppm by weight and greater than 20 ppm weight. The method in question consists in comparing the absorbance at 750 nm of a sample in solution in toluene with that of a sample in solution in heptane after filtration. The difference between the two measured values is correlated at the concentration of insoluble asphaltenes in heptane using an equation calibration. This method complements the AFNOR T60-115 method and the IP143 standard method that are used for higher concentrations.

The solvent used during step a) of deasphalting is advantageously a paraffinic solvent, a gasoline cutter or condensates containing paraffins.

Preferably, the solvent used in step a) comprises at least 50% by weight. the weight of hydrocarbon compounds having 3 to 7 carbon atoms, more preferred way between 5 and 7 carbon atoms, even more preferred 5 carbon atoms.

Depending on the solvent used, the deasphalted oil yield and the quality of this oil may vary. For example, when we go from a solvent to 3 carbon atoms to a solvent with 7 carbon atoms, the oil yield increases but, in return, the levels of impurities (asphaltenes, metals, Conradson carbon, sulfur, nitrogen ...) also increase.

The following table illustrates, by way of example, the impact of the number of carbon atoms of the hydrocarbon compounds of the solvent on the yields of deasphalted oil and on the quality of the oil when deasphalting a residue under vacuum ( RSV) Light Arabic. Solvent C3 C4 C5 Unadapted oil yield relative to the vacuum residue,% by weight based base + 30 base + 45 Characteristics of the oil Density d15 / 4 0.933 0.959 0.974 Sulfur (% by weight) 2.6 3.3 3.7 Conradson Carbon (% by weight) 1.9 5.9 7.9 Asphaltenes C7 (% by weight) <0.05 0.07 0.15 Ni (ppm) 1 3 7 V (ppm) 1.5 2.5 15.5

Moreover, for a given solvent, the choice of operating conditions in particular the temperature and the amount of solvent injected has an impact on the yield of deasphalted oil and the quality of this oil. The skilled person can choose the optimal conditions to obtain a lower asphaltene content at 3000 ppm.

Step a) of deasphalting can be carried out by any known means of the skilled person. Step a) is generally carried out in a mixer decanter or in an extraction column. Preferably, the step of deasphalting is carried out in an extraction column.

In a preferred embodiment, it is introduced into the extraction column a mixture comprising the hydrocarbon feedstock and a first fraction of a solvent charge, the volume ratio between the solvent feed fraction and the hydrocarbon feed being referred to as the rate of solvent injected with the feed. This The purpose of this step is to mix the feed with the solvent extraction column. In the settling zone at the bottom of the extractor, it is possible to introduce a second fraction of the solvent charge, the volume ratio between the second fraction of solvent charge and the hydrocarbon charge being called a rate of solvent injected at the bottom of the extractor. The volume of the hydrocarbon load considered in the settling zone is usually the one introduced into the extraction column. The sum of the two volume ratios between each of the solvent charge fractions and the hydrocarbon charge is called rate of global solvent. The decantation of the asphalt consists of the backwashing of the asphalt emulsion in the solvent + oil mixture with pure solvent. She is favored by an increase in the solvent ratio (it is actually a matter of replacing the solvent + oil environment by a pure solvent environment) and a decrease in temperature.

The overall solvent level is preferably greater than 4/1, more preferably preferred greater than 5/1.

This overall solvent content is decomposed into a level of solvent injected with the charge, preferably between 1/1 and 1.5 / 5, and a level of solvent injected extractor bottom, preferably greater than 3/1, more preferably higher at 4/1.

Moreover, in a preferred mode, a temperature gradient is established between the head and the bottom of the column to create an internal reflux, which improves the separation between the oily medium and the resins. Indeed, the solvent mixture + heated oil at the top of the extractor makes it possible to precipitate a fraction comprising resin which goes down into the extractor. The upstream countercurrent of the mixture makes it possible to dissolve the fractions at a lower temperature. consisting of resin that are the lightest.

The temperature at the extractor head is preferably between 175 and 195 ° C. The temperature at the bottom of the extractor is, for its part, preferably between 135 and 165 ° C.

The pressure inside the extractor is usually adjusted so that all products remain in the liquid state. This pressure is, of preferably between 4 and 5 MPa.

During step b) of the process of the invention, the effluent desalted in presence of hydrogen and a hydrocracking catalyst in a bed reactor bubbling according to the T-Star technology described, for example, in the article "Heavy Oil Hydroprocessing ", published by Aiche, Mar. 19-23, 1995, HOUSTON, Tex., Paper number 42 d, or according to the H-Oil technology described for example, in the published article by NPRA Annual Meeting, Mar. 16-18, 1997, J.J. Colyar and L.I. Wilson, "The H-Oil Process: A Worldwide Leader In Vacuum Residue Hydroprocessing ".

The interest of carrying out such a hydroconversion in a bed reactor ebullient, compared to a fixed bed reactor, is to be able to reach much higher conversion rates due to higher reaction temperatures important. Maximum conversion is useful for reducing the residual converted, to increase yields in gasoline, kerosene and gas oils, and to improve the quality of the products. So high conversion levels at least partially compensate for yield losses in deasphalted effluent caused by the purity constraints of the deasphalted oil of step a) of deasphalting. Thus, despite the greater amount of asphalt produced during of step a), steps a) and b) according to the invention will contribute to increasing the yield of gasoline, kerosene and gas oils.

According to a preferred embodiment of the invention, step b) is conducted with the addition of fresh catalyst and spent catalyst removal. In particular, the presence of asphaltenes reduces the activity of the catalyst in the bubbling bed in terms of hydrodesulfurization, hydrodenitrogenation, Conradson Carbon reduction, hydrogenation of aromatics, demetallisation and leads to an increase in the rate of fresh catalyst replacement.

The treatment of previously desalted effluent with a Asphaltenes (insoluble in heptane) of less than 3000 ppm by weight, allows limit the catalyst replacement rate. Indeed the deasphalted effluent has a higher reactivity and a lower deactivating power compared to the less deasphalted charge.

The conversion into light products of the deasphalted oil is defined by the following formula: 100 * (500+ ch arg e - 500+ product) 500 + ch arg e - wherein 500 ₊ filler represents the mass fraction of the deasphalted oil consisting of boiling components above 500 ° C and 500 ₊ product is the mass fraction of the product consisting of boiling components above 500 ° C.

According to the invention, the conditions of step b) make it possible to achieve a conversion of at least 50% by weight.

Preferably, the conversion of the deasphalted effluent is at least 70% by weight, more preferably at least 75% by weight, even more preferably at least 80% by weight.

The operating conditions must be chosen so as to achieve this level of performance.

This operates under an absolute pressure ranging from 5 to 35 MPa, preferably from 6 to 25 MPa, more preferably from 8 to 20 MPa. The temperature at which step b) is carried out can range from about 350 to about 550 ° C, preferably from about 380 to about 500 ° C. This temperature is usually adjusted according to the desired level of hydroconversion to light products. The hourly space velocity (VVH) and the hydrogen partial pressure are important factors that are chosen according to the characteristics of the product to be treated and the desired conversion. Most often the VVH can range from about 0.1 h ^-1 to about 10 h ^-1 , preferably from about 0.2 h ^-1 to about 5 h ^-1 . The amount of hydrogen mixed with the feed may be from about 50 to about 5000 Nm ³ / m ³ , preferably from about 100 to about 1000 Nm ³ / m ³ , more preferably from about 200 to about 500 Nm ³ / m ³ , expressed in normal cubic meters (Nm ³ ) per cubic meter (m ³ ) of liquid charge.

The catalyst of step b) is preferably a catalyst hydroconversion process comprising an amorphous support and at least one metal or metal compound having a hydrogenating function.

In general, a catalyst is used whose porous distribution is adapted to the treatment of charges containing metals.

The hydrogenating function may be provided by at least one Group VIII metal, 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 having a nickel content of 0.5 to 10% by weight, preferably 1 to 5% by weight (expressed as nickel oxide NiO) and a molybdenum content of 1 to 30% by weight can be used. weight, preferably from 5 to 20% by weight (expressed as molybdenum oxide MoO ₃ ). The total content of Group VI and VIII metal oxides can range from about 5 to about 40% by weight, preferably from about 7 to 30% by weight. In the case of a catalyst comprising metals of group VI and of group VIII, the weight ratio expressed as metal oxide between metal (or metals) of group VI on metal (or metals) of group VIII can range from about 1 to about 20, preferably from about 2 to about 10.

The catalyst support of step b) can be chosen from the group formed by alumina, silica, silica-aluminas, magnesia, clays and mixtures at least two of these minerals. This support can also contain other compounds such as, for example, oxides selected from the group consisting of boron oxide, zirconia, titanium oxide, phosphoric anhydride. Of preferably, the support is based on alumina. The alumina used is usually a beta or gamma alumina. This support, in particular in the case of alumina, can be doped with phosphorus and possibly boron and / or silicon. In this case, the concentration of phosphorus pentoxide P205 is generally lower than about 20% by weight, preferably less than about 10% by weight and minus 0.001% by weight. The concentration of boron trioxide B203 is generally between 0 and about 10% by weight. This catalyst is the most often in the form of extruded.

Preferably, the catalyst of step b) is based on nickel and molybdenum, doped with phosphorus and supported on alumina

The spent catalyst is usually replaced, in part, by catalyst cool thanks to a drawdown at the bottom of the reactor and a feed at the top of the fresh or new catalyst reactor. Racking and catalyst feed can be performed at regular time intervals, that is, for example by puff, or almost continuously or continuously. For example, we can introduce fresh catalyst every day. The replacement rate of the spent catalyst by fresh catalyst can range from about 0.05 kilogram to about 10 kilograms per cubic meter of charge. The withdrawal and the supply of catalyst are carried out using devices allowing continuous operation of step b) hydroconversion. The device in which step b) is implemented comprises generally a recirculation pump allowing the suspension to remain in suspension catalyst in the bubbling bed, by continuously reinjecting down the reactor at at least a portion of a liquid withdrawn at the top of the reactor. It is also possible to send spent catalyst withdrawn from the reactor into a regeneration zone in which one removes the carbon and the sulfur which it contains then to return this catalyst regenerated in the hydroconversion stage b).

During step c) of the process of the invention, the effluent from the stage is fractionated. b) to recover gasoline, kerosene, diesel and a first residue. This The residue contains compounds with boiling points higher than those of diesel.

The fractionation of step c) can be carried out by any known means of the skilled person such as, for example, by distillation. We can proceed to atmospheric distillation followed by vacuum distillation of the residue recovered during atmospheric distillation. As a result, the first residue can be a residue atmospheric or a vacuum residue.

Preferably, following step c), a separation of solid particles of catalyst. These catalyst particles are most often fines produced by mechanical degradation of the catalyst used in step b) hydroconversion. A rotary filter, a basket filter or still a centrifugation system such as a hydrocyclone associated with filters or a decanter online. This complementary step avoids deactivation the catalyst used in step d) because of the possible presence of molybdenum in the catalyst fines. According to a particular embodiment of this filtration stage, at least two separation means are used in parallel, one is used to carry out the separation while the other is purged from the fines of the selected catalyst.

In the case where step c) comprises a distillation under vacuum, the distillate under vacuum can be sent in a catalytic hydrocracking step.

This hydrocracking step is generally carried out on at least one fraction of the vacuum distillate in the presence of hydrogen to obtain an effluent including gasoline, kerosene, diesel and a residue.

In this hydrocracking step, at least a portion of the first residue obtained in step c) optionally with a direct distillation vacuum distillate are catalytically hydrocracked under conditions well known to man of the craft, to produce a fuel fraction (including a gasoline fraction, a kerosene fraction and a diesel fraction) which is usually sent to less in part to the fuel pools and a residue fraction.

In the context of the present invention, the expression hydrocracking catalytic system includes cracking processes comprising at least one step of conversion of the vacuum distillate fraction using at least one catalyst presence of hydrogen.

The operating conditions used during the hydrocracking step allow to achieve pass conversions, products with boiling points less than 340 ° C, and better still below 370 ° C, greater than 10% by weight and even more preferably greater than 15% by weight, or even greater than 40% in weight.

Therefore, the term catalytic hydrocracking may include Mild hydrocracking, the objective of which is to convert hydrorefining an FCC and conventional hydrocracking.

Conventional hydrocracking includes, for its part, the one-step diagrams primarily involving, in a general way, extensive hydrorefining which has purpose of carrying out extensive hydrodenitrogenation and desulfurization of the charge before the effluent is sent entirely onto the catalyst hydrocracking itself, in particular in the case where it comprises a zeolite. It also includes two-step hydrocracking that includes first step which aims, as in the "one step" process, to achieve hydrorefining the load, but also to achieve a conversion of the latter order in general from 40 to 60%. In the second step of a process two-stage hydrocracking process, only the fraction of the feed that is not converted during the first step is treated.

Conventional hydrorefining catalysts usually contain minus an amorphous support and at least one hydro-dehydrogenating element (usually at least one element of groups VIB and VIII non-noble, and the most often at least one element of group VIB and at least one element of group VIII not noble).

Dies that can be used in the hydrorefining catalyst alone or as a mixture are, by way of example, alumina, halogenated alumina, silica, silica-alumina, clays (chosen for example from clays such as kaolin or bentonite), magnesia, titanium oxide, boron oxide, zirconia, aluminum phosphates, phosphates of titanium, zirconium phosphates, coal, aluminates. We prefer to use matrices containing alumina, in all known forms of human and even more preferably aluminas, for example alumina gamma.

The catalysts described above are generally employed to ensure the cracking of the vacuum distillate fraction in a mild hydrocracking process, hydrorefining and in the hydrorefining step of conventional hydrocracking.

To obtain this cracking, the charge is generally brought into contact, in the presence of hydrogen, with at least one catalyst as described above, at a temperature between 330 and 450 ° C., preferably between 360 and 425 ° C., under a pressure of between 4 and 25 MPa, preferably less than 20 MPa, with a space velocity of between 0.1 and 6 h ^-1 , preferably between 0.2 and 3 h ^-1 , and a quantity of hydrogen introduced. such that the volume ratio in liters of hydrogen per liter of hydrocarbon is between 100 and 2000 I / I.

In the case of a conventional hydrocracking, the vacuum distillate fraction undergoes in the hydrorefining zone, a hydrotreatment pushed on a catalyst such as described above, in order to be hydrodesulfurized and hydrodenitrogenated before being introduced in whole or in part into a second reaction zone containing a hydrocracking catalyst.

The operating conditions used in the reactor (s) of this second reaction zone are generally a temperature greater than 200 ° C., often between 250 ° -480 ° C., advantageously between 320 ° C. and 450 ° C., preferably between 330 ° and 420 ° C. a pressure of between 5 and 25 MPa, preferably less than 20 MPa, a space velocity of between 0.1 and 20 h ^-1 and preferably between 0.1 and 6 h ^-1 , preferably between 0.2 and 3 h ^{- 1} , and a quantity of hydrogen introduced such that the volume ratio in liters of hydrogen per liter of hydrocarbon is between 80 and 5000 I / I, most often between 100 and 2000 I / I.

This reaction zone generally comprises at least one reactor containing at least one fixed bed of hydrocracking catalyst. This fixed bed of hydrocracking catalyst may be preceded by at least one fixed bed of a catalyst hydrorefining as described above. Hydrocracking catalysts used in hydrocracking processes are generally of the bi-functional type associating an acid function with a hydrogenating function. The acid function can be provided by supports having a large surface area (150 to 800 m2.g-1 generally) and having superficial acidity, such as aluminas halogenated (chlorinated or fluorinated in particular), the combinations of boron oxides and of aluminum, amorphous silica-aluminas known as hydrocracking catalysts amorphous and zeolites. The hydrogenating function can be provided either by a or more metals of Group VIII of the Periodic Table of Elements, either by a combination of at least one Group VIB metal of the classification and at least one Group VIII metal.

The hydrocracking catalyst may comprise at least one acid function crystallized such as a zeolite Y, or an amorphous acid function such as a silica-alumina, at least one matrix and a hydro-dehydrogenating function. Optionally, it may also comprise at least one element chosen from boron, phosphorus and silicon, at least one element of group VIIA (chlorine, fluorine for example), at least one element of group VIIB (manganese for example), least one element of the group VB (niobium for example).

During step d) of the process of the invention, a cracking is carried out catalytically at least a part of the first residue to obtain an effluent comprising gasolines, kerosene, gas oils and a second residue.

The specific deasphalting conditions of step a) of the process of the invention are such that the first residue from the effluent of step b) hydroconversion has a level of purity sufficient to allow cracking performing well in step d). In particular, step a) according to the invention allows to obtain an effluent at the outlet of step b) preferably having a content of Conradson carbon less than 10% by weight, more preferably less than 5% by weight and a nitrogen content of less than 3000 ppm, which is favorable for obtaining a high conversion of the residue of step b) associated with obtaining yields of gasoline, kerosene and high diesel. So the conditions of severity of step a) of deasphalting combined with the conditions of step b) hydroconversion and step d) cracking contribute to increase the yield of gasolines, kerosene and gas oils of the process of the invention and improve the quality of these products. Note also that in the case where the step d) hydrocracking, the products from catalytic cracking and catalytic hydrocracking are of sufficient quality to be exploitable directly or with few post-treatments.

At least a portion of the first residue obtained in step c) is cracked catalytically under conditions well known to those skilled in the art for produce on the one hand a fuel fraction (comprising a gasoline fraction and a diesel fraction) that is usually sent at least partly to the pools fuels and on the other hand, a slurry fraction which may be, at least in part, even entirely, sent to the heavy fuel pool or recycled at least in part, or even all, in step d) of catalytic cracking. In the context of the present invention the conventional catalytic cracking term includes cracking processes comprising at least one partial combustion regeneration step and those comprising at least one full combustion regeneration step and / or those comprising at least one partial combustion step and at least one total combustion stage.

This catalytic cracking may be as described in Ullmans Encyclopedia of Industrial Chemistry Volume A 18, 1991, pages 61 to 64. usually a conventional catalyst comprising a matrix, optionally a additive and at least one zeolite. The amount of zeolite is variable but usually from about 3 to 60% by weight, often from about 6 to 50% by weight and most often from about 10 to 45% by weight. Zeolite is usually dispersed in the matrix. The amount of additive is usually about 0 to 30% by weight and often from about 0 to 20% by weight. The amount of matrix represents the complement at 100% by weight. The additive is usually selected from the group formed by the oxides of metals in group IIA of the periodic table of such as, for example, magnesium oxide or calcium oxide, rare earth oxides and titanates of Group IIA metals. The matrix is the more often a silica, an alumina, a silica-alumina, a silica-magnesia, a clay or a mixture of two or more of these products. The most zeolite commonly used is zeolite Y.

Cracking is carried out in a substantially vertical reactor either in ascending (riser) or in descending mode (dropper). The choice of catalyst and operating conditions depends on the products sought according to the load treated as is for example described in the article by M. Marcilly pages 990-991 published in the review of the Institut Français du Pétrole November-December 1975 pages 969-1006. It is usually carried out at a temperature of about 450 to about 600 ° C and residence times in the reactor less than 1 minute, often about 0.1 to about 50 seconds.

The catalytic cracking may also be catalytic cracking in a fluidized bed, for example according to the process developed by the Applicant called R2R. This catalytic cracking in a fluidized bed can be carried out conventionally those skilled in the art under the appropriate conditions of cracking with a view to to produce hydrocarbon products of lower molecular weight. The reactor catalytic cracking in a fluidized bed can operate with updraft or current descending. Although this is not a preferred form of realization of the the present invention, it is also conceivable to carry out catalytic cracking in a moving bed reactor. Catalytic cracking catalysts particularly preferred are those containing at least one zeolite usually mixed with a suitable matrix such as for example alumina, silica, silica-alumina.

The effluent obtained in step d) is generally fractionated to recover at least one gasoline fraction, a kerosene fraction, diesel fuel and a second residue. This fractionation can be achieved by any means known to the man of the such as, for example, by distillation. Generally, we proceed to a atmospheric distillation followed by vacuum distillation of the residue recovered during atmospheric distillation.

Figures 1 and 2 show schematically the main variants for carrying out the method according to the present invention.

In FIG. 1, the hydrocarbon feedstock to be treated enters the line 1 in the deasphalting section 2 in the presence of a solvent, said solvent being introduced by line 3. The asphalt fraction plus some of the solvent injected in Section 2 is withdrawn via line 4 and directed to a separation section 5 of the solvent and asphalt. The asphalt is drawn off by line 6. The solvent is drawn off by line 7 and reinjected in section 2 by lines 8, 1 and 3. The deasphalted fraction, called commonly deasphalted oil, plus some of the solvent injected into section 2 is withdrawn through line 9 and directed to a section 10 of solvent separation and unadapted oil. The solvent is withdrawn from line 8 and reinjected into the section 2 by lines 8, 1 and 3. The deasphalted oil to be hydrocracked enters line 11 in the boiling bed hydroconversion section 12. The catalyst booster made by the line 13 and the withdrawal line 14. The hydrogen is introduced by the line 15. The effluent treated in section 12 is sent via line 16 to a section 17 separation from which, after relaxation, the line 18 effluent that is sent to distillation section 19 from which one recovers a gas fraction by the line 20, a gasoline fraction by the line 21, a kerosene fraction by line 22 and a diesel fraction by line 23. The residual atmospheric is sent through line 24 in section 25 cracking Catalytic. The effluent from the catalytic cracking section is sent through the line 24 to a distillation section 27 from which we retrieve via line 28 a gaseous fraction, by line 29 a gasoline fraction, by line 30 a diesel fraction and by line 31 a slurry fraction which is partly sent to the pool heavy fuel oil from the refinery, another part of this slurry fraction being possibly sent via line 32 into the catalytic cracking section 25, another part possibly being sent to the processing section 12 in bed bubbly. Part of the diesel fraction of line 23 is possibly sent with the residue of line 24 in the catalytic cracking section 25. Part of the gasoline fraction of line 21 or 22 is eventually sent with the residue of line 24 in the catalytic cracking section 25.

In the particular embodiment of the invention shown diagrammatically in FIG. obtained in section 19 is sent via line 24 to distillation under vacuum 50 where a vacuum distillate fraction is recovered via line 51 and a fraction vacuum residue by line 52. The vacuum distillate fraction is sent to a catalytic hydrocracking zone. The vacuum residue fraction is sent by line 52 to a catalytic cracking zone 25 according to the described process in Figure 1.

The following examples, from experiments conducted in units pilots, illustrate the present invention.

Example

A vacuum residue (RSV) of heavy crude oil is deasphalted with pentane: The vacuum residue has the following properties: Properties of the Vacuumed Residue D15 / 4 1.06 Sulfur,% by weight 5.7 Ni + V, ppm weight 500 Nitrogen, ppm by weight 6800 Insoluble Asphaltenes C7,% by weight 17 Carbon Conradson,% weight 25

The operating conditions of the deasphalting step are as follows: Overall dilution rate, v / v 5/1 Solvent content injected with the charge, v / v 1/1 Solvent content in bottom of extractor, v / v 4/1 Extractor head temperature, ° C 188 Extractor bottom temperature, ° C 158 Extractor pressure, MPa 4.2

A deasphalted oil is produced with a yield of 62% by weight and an asphalt is produced with a yield of 38% by weight. All returns are calculated from a base 100 (by mass) of vacuum residue.

The deasphalted oil has the following properties: Deasphalted oil Specific density 1.01 Nickel + Vanadium content, ppm by weight 130 Sulfur content,% by weight 4.6 Nitrogen content,% by weight 0.42 Conradson Carbon,% by weight 12.0 Asphaltenes content (insoluble in heptane) NF-T 60-115,% by weight <0.05

Disaspahalated oil is mainly characterized by its asphaltenes (insoluble in heptane) according to standard NF-T 60-115 lower than 0.05% by weight which makes it a clean, unadulterated oil of very high quality.

This deasphalted oil is then introduced, in the presence of hydrogen, in a pilot reactor in a bubbling bed in order to obtain a conversion of 85% weight of fraction 524 ° C +.

This reactor contains 1 liter of a specific catalyst for the T-STAR® application manufactured by AXENS under the reference HTS-458 which is specific to bubbling bed treatment of heavy loads containing metals.

• VVH par rapport au lit catalytique tassé : 0.8 h-1
• Pression d'hydrogène : 13,5 MPa
• Recyclage d'hydrogène : 600 litres d'hydrogène par litre de charge
• Température dans le réacteur : 435°C
• Age du catalyseur: 29 jours

The operating conditions of implementation are as follows:

• VVH compared to packed catalytic bed: 0.8 h-1
• Hydrogen pressure: 13.5 MPa
• Hydrogen recycling: 600 liters of hydrogen per liter of charge
• Temperature in the reactor: 435 ° C
• Catalyst age: 29 days

The overall performance of the catalyst is as follows: HDS desulfurization rate,% 96.7 HDN denitration rate,% 71 Carbon conversion rate Conradson HDCCR,% 90 HDM demetallization rate,% 99.9

The degree of purification of an impurity X is defined as follows: 100 * (Xch arg e - Xproduit) Xcharge where Xcharge represents the impurity content of the charge
and Xproduct represents the impurity content of the liquid product

The yield structure obtained after laboratory TBP distillation of the liquid effluent at atmospheric flash at the outlet of the bubbling bed reactor is as follows: Chopped off Yield weight compared to deasphalted oil Essence1 16 Kérosène1 13 Gazole1 18 Atmospheric residue1 42

At this stage, the yields of gasoline, kerosene and diesel relative to the non-deasphalted vacuum residue are as follows: Chopped off Yield weight relative to the undissued vacuum residue Essence1 16 * 0.62 = 9.9 Kérosène1 13 * 0.62 = 8.1 Gazole1 18 * 0.62 = 11.2 Résidu1 42 * 0.62 = 26.0

The qualities of the associated products are as follows: Essence1 Sulfur / nitrogen, ppm weight <50/10 Density 0.737 Kerosene 1 Sulfur / nitrogen, ppm weight 210/175 Density 0.824 Gazole1 Sulfur / nitrogen, ppm weight 280/500 Density 0.866 Number of cetane, ASTM D613 46 Atmospheric residue1 Sulfur / nitrogen, ppm weight 2950/2320 Density 0.932 NMR hydrogen,% by weight 11.8 Ni + V, ppm weight <1 CCR,% weight 2.5

The distillates produced at the end of this stage, in particular diesel, possess qualities which make it possible to envisage a moderate hydrotreatment in order to to meet current specifications.

The atmospheric residue1, called the first residue in the present invention, is processed in a conventional catalytic cracking unit. The residue thus prepared has, in fact surprisingly, properties of purity and remarkable hydrogenation. In particular this residue is characterized by a carbon Conradson weak that limits the formation of coke.

The conversion of this residue in a unit of this FCC to 74% by weight of the 360 ° C + fraction in a maxi-gasoline step gives the following yields: Gas and LPG % weight of the atmospheric residue 18.6 Essence2 % weight of the atmospheric residue 47.6 Sulfur content, ppm weight 90 Diesel 2 (LCO) % weight of the atmospheric residue 14.8 Sulfur content,% by weight 0.390 Slurry (second residue according to the invention) % weight of the atmospheric residue 11.6 Coke % weight of the atmospheric residue 7.4

Finally, after the steps of deasphalting, bubbling bed hydroconversion and catalytic cracking, the overall yields of gasoline, kerosene and diesel relative to the non-deasphalted vacuum residue are as follows: Chopped off Yield weight relative to the undissued vacuum residue Essence1 + Essence2 9.9 + 12.4 = 22.3 Kérosène1 8.1 Gazole1 + Gazole2 11.2 + 3.8 = 15.0 Résidu2 3.0 Asphalt 38

The distillates produced are furthermore characterized by levels of low impurities (eg diesel sulfur) which will require moderate additional hydrotreatments in order to reach the specifications in force. These distillates can therefore be valued commercially so individual.

Claims (11)

A process for treating a hydrocarbon feedstock of which at least 95% by weight consists of compounds having a boiling point of at least 340 ° C, characterized in that it comprises the following steps, in which: a) the charge is brought into contact with a solvent so as to obtain a deasphalted effluent having a content of asphaltenes (insoluble in n-heptane according to standard NF-T-60-115) of less than 3000 ppm by weight, b) the deasphalted effluent in the presence of hydrogen and a hydrocracking catalyst is cracked in a bubbling bed reactor so as to convert at least 50% by weight of the fraction of the deasphalted effluent boiling above 500 ° C in compounds having a boiling point below 500 ° C, c) the effluent from step b) is fractionated to recover gasolines, kerosene, gas oils and a first residue, and d) at least a portion of this first residue is catalytically cracked so as to obtain an effluent comprising gasolines, kerosene, gas oils and a second residue. Process according to Claim 1, characterized in that the hydrocarbon feedstock has a final boiling point above 600 ° C. Process according to either of Claims 1 and 2, characterized in that the hydrocarbon feedstock essentially comprises atmospheric residues and vacuum residues of heavy crudes. Process according to any one of Claims 1 to 3, characterized in that the asphaltene content of the deasphalted effluent is less than 1000 ppm by weight. Process according to any one of Claims 1 to 3, characterized in that the asphaltene content of the deasphalted effluent is less than 500 ppm by weight. Process according to any one of Claims 1 to 5, characterized in that the solvent used in stage a) comprises at least 50% by weight of hydrocarbon compounds having 3 to 7 carbon atoms. Process according to any one of Claims 1 to 6, characterized in that the deasphalting step is carried out in an extraction column. Process according to any one of claims 1 to 7, characterized in that the catalyst of step b) is a hydroconversion catalyst comprising an amorphous support and at least one metal or metal compound having a hydrogenating function. Process according to any one of Claims 1 to 8, characterized in that a separation of the solid catalyst particles is carried out in step c). The method of any one of claims 1 to 9, wherein the step c) comprises atmospheric distillation followed by vacuum distillation. Process according to claim 10, wherein the vacuum distillate is sent in a hydrocracking step.

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