RU2569849C2 - Method of hydroconversion of oil fractions as per slurry-technology, ensuring extraction of catalyst metals and raw stock including extraction stage - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: invention relates to the method of the hydroconversion of heavy oil fractions, including stage of the raw stock hydroconversion in at least one reactor, containing suspended catalyst, ensuring the ability for metals recuperation from the residual unconverted fraction, in particular used as catalyst. The method includes stage of the hydroconversion, stage of gas/liquid separation, at least one stage of extraction liquid/liquid, combustion stage, stage of metals extraction, and stage of catalytic solutions making, that circulate to stage of the hydroconversion.

EFFECT: recuperation and return to cycle of all metals escaped from catalysts and heavy fractions.

13 cl, 3 dwg

Description

The invention relates to a method for hydroconversion of heavy oil fractions into lighter products that can be used as fuel and / or raw materials for petrochemicals. More specifically, the invention relates to a method for the hydroconversion of heavy oil fractions, comprising the step of hydroconversion of the feed in at least one reactor containing a suspended catalyst, and recovering metals from the residual unconverted fraction, in particular, metals used as catalysts, to reuse them in catalytic solutions and return to the beginning of the cycle of the conversion process on a suspended catalyst. The method comprises a hydroconversion stage, a gas / liquid separation step, at least one liquid / liquid extraction step, a burning step, a metal extraction step, and a step for producing a catalytic solution or solutions that are recycled to the hydroconversion step.

The conversion of heavy petroleum fractions into liquid products can be carried out by heat treatment or hydrogenation treatment, also called hydroconversion. Modern research is focused mainly on hydroconversion, since heat treatment usually gives products of mediocre quality and a fairly noticeable amount of coke.

Hydroconversion of heavy fractions involves the conversion of raw materials in the presence of hydrogen and a catalyst. Industrial methods employ, depending on the feed, fixed bed technology, fluidized bed technology or suspended catalyst technology (slurry technology).

Hydroconversion of heavy fractions in a fixed bed or in a fluidized bed is carried out on catalysts containing one or more transition metals (Mo, W, Ni, Co, Ru) supported on silica / alumina substrates or equivalent.

For the conversion of heavy fractions, in particular, containing heteroatoms, metals, and asphaltenes, the fixed-bed technology is usually limited in use, since the contaminants cause rapid catalyst deactivation, which requires too frequent renewal of the catalyst layer and, therefore, is expensive. In order to process this type of raw material, fluidized bed processes have been developed. However, the conversion level in fluidized bed technologies is usually limited to below 80% due to the used catalyst system and plant design.

Slurry-based hydroconversion technologies provide an attractive solution for eliminating the disadvantages encountered when using a fixed bed or fluidized bed. Indeed, slurry technology makes it possible to process heavy fractions heavily contaminated with metals, asphaltenes and heteroatoms, giving at the same time a degree of conversion of usually more than 85%.

Slurry residual hydroconversion technologies utilize a catalyst dispersed in the form of very fine particles below 1 mm in size, preferably several tens of microns or less (usually from 0.001 to 100 microns). Due to such a small particle size of the catalyst, hydrogenation reactions are facilitated due to uniform distribution throughout the reaction zone, and coke formation is greatly reduced. The catalysts or their precursors are introduced together with the raw materials, the conversion of which must be carried out, at the inlet of the reactors. The catalysts pass through the reactors along with the raw materials and products during the conversion, then they are carried away with the reaction products out of the reactors. After separation, they are in a heavy residual fraction, such as, for example, the unconverted residue of vacuum distillation. The catalysts used in suspension are usually sulfonated catalysts containing preferably at least one element selected from the group consisting of Mo, Fe, Ni, W, Co, V and / or Ru. Typically, molybdenum and tungsten exhibit much more satisfactory characteristics than nickel, cobalt or ruthenium, and more so than vanadium and iron (N. Panariti et al ., Applied Catalysis A: General 204 (2000), 203-213).

Industrial technologies for the conversion of heavy fractions by slurry technology are known. Examples include EST technology patented by ENI, VRSH technology patented by Chevron-Lummus-Global, HDH and HDHPLUS technology patented by Intevep, SRC-Uniflex technology patented by UOP, (HC) 3 technology patented by Headwaters, etc.

Although the small particle size of the suspended catalysts provides a very high degree of conversion, this size is problematic with respect to the separation and recovery of the catalyst or catalysts after the hydroconversion reaction. After separation, the catalysts are in a heavy residual fraction, such as, for example, the unconverted residue of vacuum distillation. In some methods, a portion of the vacuum distillation residue containing the unconverted fraction and catalysts is immediately recycled to the hydroconversion reactor to increase the conversion yield. However, these recovered catalysts usually do not have any activity or have much lower activity than fresh catalyst. In addition, the remainder of vacuum distillation is traditionally used as fuel for the production of heat, electricity and slag. These slags contain metals and are usually sent to landfill. Therefore, in this case, the metals are not recovered.

In addition, the deactivation of the catalysts requires regular replacement, resulting in the need for fresh catalysts. Treated heavy fractions contain metals in high concentration, mainly vanadium and nickel. These metals are mostly removed from the feed, precipitating on the catalysts during the reaction. They are carried away by the catalyst particles leaving the reactor. Similarly, the deactivation of the catalysts is enhanced due to the formation of coke, due in particular to the high concentration of asphaltenes contained in these fractions.

Continuous updating of the catalytic phase, finely distributed in the reaction zone, makes it possible, upon contact with hydrogen dissolved in the liquid phase, to carry out hydrogenation and hydrotreating of the injected heavy fraction. In order to ensure a high level of conversion and maximum hydrotreating of the feedstock, the amount of catalytic solution introduced is rather high, which leads to a sufficiently high operational cost at the industrial level. Thus, the hydroconversion processes on a suspended catalyst usually consume a large number of catalysts, in particular, the molybdenum present in the catalyst, which is the most active, but also the most expensive. The costs of fresh catalyst, catalyst separation and metal recovery have a big impact on the profitability of such processes. The selective recovery of molybdenum and its return to the cycle as a catalyst are two indispensable factors for increasing the industrial value of slurry technology. This extraction is also accompanied by the extraction of other metals, such as nickel (which is introduced and which accumulates in the feed) and vanadium, which collects in the feed, the content of which is comparable to the molybdenum content and which can be resold for use in metallurgy.

In addition to these economic aspects, the recovery of metals is also necessary for environmental reasons. Indeed, the slag generated by burning the residual fraction is considered a hazardous waste in many countries, as the metals contained in the slag located at the waste collection sites pose a hazard to groundwater.

Thus, there is a real need for the recovery and return to the cycle of metals released from the catalysts and heavy fractions during the process of hydroconversion on a suspended catalyst.

State of the art

Methods for the recovery of metals by slurry technology are known in the art.

Thus, US patent application 2008/0156700 describes a process for separating catalysts in the form of ultrafine particles formed during the hydroconversion process on a suspended catalyst, including the step of precipitating or flocculation of the heavy fraction containing the metal parts with heptane solvents, the stage of separation of the heavy fraction from the light fraction by centrifugation and a coking step in the temperature range from 350 ° to 550 ° C in an inert atmosphere, to obtain coke containing a catalyst. This coke can be subjected to a metal extraction step.

U.S. Pat. This catalyst is then subjected to metal extraction steps, and the metals are recycled to the process.

US 4,545,700 describes a process for the hydroconversion of heavy fractions on a suspended catalyst, comprising, after the hydroconversion reaction, a gaseous fraction separation step, a distillation step, washing the remainder of the distillation at atmospheric pressure (650 ° F ⁺ = 343 ° C ⁺ ) with toluene at atmospheric pressure and temperature environment and the stage of combustion or gasification of the solid fraction at temperatures of 427-1093 ° C (800-2000 ° F), to obtain slags containing metals. Metals V and Mo are recovered through an extraction step with oxalic acid, and then recycled to the process.

US 6,511,937 describes a process for the hydroconversion of heavy fractions on a suspended catalyst, comprising, after the hydroconversion reaction, a separation step in a high pressure and low temperature separator, providing a very light fraction to be separated, a step for deasphalting the entire residual fraction with C3-C5 paraffin solvents at ambient temperature medium, a coking step (427-649 ° C, without air) and / or a burning step at temperatures below 649 ° C, to produce slag containing a catalyst. This catalyst can then be subjected to metal extraction steps and returned to the process.

Object of invention

The fact that the specificity of slurry technology is the use of a finely dispersed catalyst, rather than a catalyst deposited on the mineral phase, makes the extraction of metals much more complicated than in the case of traditionally used supported oil refining catalysts. The bet on the industrial development of hydroconversion methods using slurry technology requires the extraction and return to the cycle of metals released from the catalysts.

The present invention is aimed at improving the methods of hydroconversion of heavy fractions according to the known slurry technology, providing reuse of the unconverted residual fraction formed upon conversion on a suspended catalyst, and this fraction has a high concentration of metals and heteroelements, and includes, at the end, the accumulation of these metals in the specified unconverted fraction and obtaining catalyst precursors with the aim of returning them to the initial cycle of the slurry conversion process. The method includes a hydroconversion stage, a gas / liquid separation step, a liquid / liquid extraction step, a combustion step, a metal extraction step, and a step for producing a catalyst solution or solutions that are recycled to the hydroconversion step.

The research work carried out by the author on the hydroconversion of heavy fractions led to the unexpected discovery that this method, including separation, makes it possible to maximize the proportion of the light fraction leaving the hydroconversion reactor and minimize the proportion of the residual fraction, in combination with the high-temperature liquid / the liquid with aromatic and / or naphthenoaromatic and / or polar solvents, and a moderate burning stage that prevents the sublimation of metals, makes it possible It is possible to achieve such an extraction of metals contained in slags that it is possible to obtain a very high degree of extraction of metals that can be returned to the process. Indeed, the critical stages of this extraction are, first of all, the concentration of metals in the carbon matrix (through extraction), then the formation of the mineral phase (through moderate combustion) containing elemental metals precipitated from the catalyst (Mo and Ni), as well as from raw materials (Ni , V and Fe), and not containing carbon.

The benefit of the method proposed by the invention is to enable the reuse of the unconverted residual fraction having a high concentration of metals and heteroelements, which ensures the extraction of these metals and the preparation of catalyst precursors in order to return them to the initial cycle of the conversion process using slurry technology.

Another advantage of the method is to optimize the degree of hydroconversion by gas / liquid separation after hydroconversion, operating in conditions close to the operating conditions in the reactor and enabling efficient separation of the light fraction containing the future base fuel (gases, naphtha, light gas oil and even heavy gas oil) from an unconverted residual fraction containing solids such as metals. Thus, the yield of the light fraction is maximally increased and at the same time the content of the unconverted residual fraction is minimized, which subsequently facilitates a decrease in the concentration of metals in it. Maintaining the operating conditions during the separation also makes it possible to economically integrate further processing, by hydrotreating and / or hydrocracking, of a light fraction without the need for additional compressors.

Another advantage of the method is the liquid / liquid extraction with an aromatic and / or naphthenoaromatic and / or polar solvent of the unconverted fraction containing metals at elevated temperatures, which makes it possible to efficiently extract insoluble compounds (and, therefore, to concentrate metals).

Another advantage of the method is burning at a moderate temperature, which makes it possible to separate the organic phase from the inorganic phase containing metals in order to facilitate subsequent extraction of metals from the inorganic phase, preventing evaporation and / or sublimation (and, consequently, loss) of metals during combustion.

Thus, the method of the present invention makes it possible to optimize the conversion of heavy fractions to base fuel, ensuring the extraction of metals with achieving good degrees of extraction.

DETAILED DESCRIPTION OF THE INVENTION

The invention relates to a method for the hydroconversion of heavy oil fractions on a suspended catalyst, providing extraction and reuse of metals from the residual unconverted fraction, in particular, used as catalysts.

More specifically, the invention relates to a method for hydroconversion of heavy oil fractions containing metals, including

a) a step for hydroconversion of the feed in at least one reactor containing a suspended catalyst containing at least one metal and optionally a solid additive,

b) the step of separating the hydroconversion products without reducing the pressure, to obtain a fraction called light, containing compounds boiling at a temperature of not more than 500 ° C, and a residual fraction,

b ') optionally a fractionation step comprising vacuum separating said residual fraction obtained in step b) to obtain a high metal content vacuum distillation residue,

c) a liquid / liquid extraction step of the indicated residual fraction obtained in step b) and / or the indicated vacuum distillation residue obtained in step b ′), at a temperature in the range of 50 to 350 ° C. aromatic and / or naphthenoaromatic, and / or a polar solvent, to obtain an extract with a high content of metals and raffinate,

d) a step of burning said extract at a temperature in the range of 200 to 700 ° C. to obtain high metal content slags,

e) a step for extracting metals from slags obtained in the burning step,

f) a step for producing a solution or solutions of a metal containing at least a catalyst metal that are recycled as a catalyst to a hydroconversion step.

Hydroconversion

The method of the present invention comprises a step for hydroconversion of the feed in at least one reactor comprising a suspended catalyst and optionally a solid additive.

By hydroconversion is understood the reactions of hydrogenation, hydrotreating, hydrodesulfurization, hydrodeazotization, hydrodemetallization and hydrocracking.

The heavy fractions considered are hydrocarbon oil fractions such as oil residues, crude oil, oil with the lightest fractions selected, deasphalted oils, asphalts or bitumen from deasphalting, derivatives of oil conversion processes (such as: HCO, sludge with FCC, heavy GO / VGO from coking, residues of a viscosity reduction process or similar thermal processes, etc.), tar sands or their derivatives, tar tails or their derivatives, or mixtures of such raw materials. More specifically, in this case, the term "heavy fraction" combines hydrocarbon fractions containing at least 50% of the mass. product boiling at a temperature of more than 250 ° C, and at least 25% of the mass. product boiling at temperatures above 350 ° C.

Consider the heavy fractions of the present invention contain metals, mainly V and / or Ni, in an amount of usually at least 50 ppm, usually 100-2000 ppm, at least 0.5% of the mass. sulfur and at least 1% of the mass. asphaltenes (heptane asphaltenes), usually more than 2% of the mass. or 5% wt., and the content of asphaltenes can reach 25% of the mass. or more; they also contain conversion-resistant condensed aromatic structures that may contain hetero elements.

Preferably, the considered heavy fractions are unusual oils such as heavy crude oil (° API in the range of 18 to 25 and viscosity from 10 to 100 cPs), extra heavy crude oil (° API from 7 to 20 and viscosity from 100 to 10,000 cPs) and tar sands (° API from 7 to 12 and viscosity below 10,000 cPs), present in large quantities in the Athabasca Basin area in Canada and Orinoco in Venezuela, where reserves are estimated at 1,700 and 1,300 gigabarrels respectively. These unusual oils are also characterized by a high content of vacuum distillation residues, asphaltenes and heteroelements (sulfur, nitrogen, oxygen, vanadium, nickel, etc.), which requires special stages of conversion into industrial products such as gasoline, gas oil or heavy fuel oil.

The heavy fraction is mixed with a stream of hydrogen and carefully with a distributed catalyst to achieve the most uniform hydrogenation activity in the hydroconversion reaction zone. Preferably, a solid additive that improves the hydrodynamics of the reactor is also added. This mixture is fed to the hydroconversion section on a suspended catalyst. This section consists of a heating furnace for raw materials and hydrogen and a reaction section consisting of one or more reactors installed in series and / or in parallel, depending on the required capacity. In the case of series reactors, one or more flow separators may be in front of each reactor. In the reaction section, hydrogen can feed one, several, or all of the reactors in equal or different proportions. In the reaction section, the catalyst may be supplied in one, several or all reactors in equal or different proportions. The catalyst is held in suspension in the reactor and moves from bottom to top in the reactor along with the gas and feed and is discharged with the effluent. Preferably, at least one (preferably all) of the reactors is equipped with an internal recirculation bed.

The operating conditions in the hydroconversion section on a suspended catalyst are usually as follows: pressure from 2 to 35 MPa, preferably from 10 to 25 MPa, with a partial pressure of hydrogen ranging from 2 to 35 MPa, preferably from 10 to 25 MPa, a temperature in the range of 300 ° C to 500 ° C, preferably from 420 ° C to 480 ° C, contact time from 0.1 h to 10 h with a preferred duration of from 0.5 h to 5 hours

These operating conditions in combination with catalytic activity make it possible to obtain a degree of conversion in one pass of the residue of vacuum distillation of 500 ° C ⁺ , which can be from 20 to 95%, preferably from 70 to 95%. The above conversion is defined as: mass fraction of organic compounds having a boiling point of more than 500 ° C at the inlet of the reaction section, minus the mass fraction of organic compounds with a boiling point of more than 500 ° C at the outlet of the reaction section, the result divided by the mass fraction organic compounds with a boiling point of more than 500 ° C at the entrance to the reaction section.

The suspended catalyst is dispersed in the reaction medium. It can be obtained in situ , but preferably, it is prepared outside the reactor and introduced, usually continuously, together with the feed. The catalyst facilitates the hydrogenation of radicals resulting from thermal cracking and reduces the formation of coke. When coke is formed, it is removed along with the catalyst.

The suspended catalyst is a sulfonated catalyst containing preferably at least one element selected from the group consisting of Mo, Fe, Ni, W, Co, V, Ru. These catalysts are usually monometallic or bimetallic (for example, a combination of a base element of group VIIIB (Co, Ni, Fe) and an element of group VIB (Mo, W)). Preferably, NiMo, Mo or Fe catalysts are used. The catalysts used may be powders of dissimilar solids (such as natural minerals, ferrous sulfate, etc.), dispersed catalysts prepared from water soluble dispersed catalyst precursors, such as phosphoromolybdic acid, ammonium molybdate or a mixture of Mo or Ni oxide with aqueous ammonia. Preferably, the catalysts used are obtained from precursors soluble in the organic phase ("oil soluble dispersed catalyst"). Precursors are organometallic compounds, such as Mo, Co, Fe or Ni naphthenates, or such as polycarbonyl compounds of these metals, for example, Mo or Ni 2-ethylhexanoates, Mo or Ni acetylacetonates, C ₇ -C ₁₂ fatty acid salts of molybdenum or tungsten, and etc. They can be used in the presence of surfactants to improve the dispersion of metals when the catalyst is bimetallic. The catalysts are in the form of dispersed colloidal or non-colloidal particles, depending on the nature of the catalyst. Such precursors and catalysts suitable for the process of the present invention are widely described in the literature.

Typically, the catalysts are prepared prior to introduction into the feed. The production method is selected depending on the state in which the precursor is located, and on its nature. In all cases, the precursor is sulfonated ( ex-situ or in-situ ) to obtain a catalyst suspended in the feed. For preferred catalysts called oil soluble, in the conventional method, the precursor is mixed with the oil fraction (which may be part of the processed feed, external fraction, recycled fraction, etc.), the mixture is dried (optionally), at least partially, then or simultaneously sulfonated by adding a sulfur-containing compound (preferably H ₂ S) and heated. The preparation of such catalysts is described in the art.

Preferred solid additives are inorganic oxides such as alumina, silica, mixed Al / Si oxides, spent supported catalysts (e.g., supported on alumina and / or silica) containing at least one element of group VIII (such as Ni, Co) and / or at least one element of the VIB group (such as Mo, W). Call, for example, the catalysts described in application US 2008/77124. Solid carbides with a low hydrogen content (e.g., 4% hydrogen), optionally pretreated, can also be used. Mixtures of such additives may also be used. The sizes of these particles are preferably below 1 mm. The content of the optional solid additive present at the entrance to the reaction zone of the hydroconversion process on the suspended catalyst is from 0 to 10% by weight, preferably from 1 to 3% by weight, and the content of catalytic solutions is from 0 to 10% by weight, preferably , from 0 to 1% of the mass.

Known methods for the hydroconversion of heavy fractions by slurry technology are the EST method of the ENI concern, operating at temperatures of about 400-420 ° C and a pressure of 10-16 MPa with a suspended catalyst (molybdenum); Headwaters method (HC) 3, operating at temperatures of the order of 400-450 ° C and pressures of 10-15 MPa with iron pentacarbonyl or molybdenum 2-ethylhexanoate, the catalyst being dispersed in the form of colloidal particles; HDH and HDHPLUS methods, patented by Intevep / PDVSA, operating at temperatures of the order of 420-480 ° C and pressures of 7-20 MPa, using a dispersed metal catalyst; a Chevron CASH method using a sulfonated Mo or W based catalyst prepared in an aqueous manner; UOP SRC-Uniflex method operating at temperatures of the order of 430-480 ° C and pressures of 10-15 MPa; the VCC method, developed by Veba (owned by BP), operating at temperatures of the order of 400-480 ° C and pressures of 15-30 MPa, using an iron-based catalyst; Exxonmobil microcat method, etc.

All of these slurry technologies are applicable in the method of the present invention.

Separation

The entire stream leaving the hydroconversion is directed to a separation section, usually to a high pressure and high temperature (HPHT) separator, which makes it possible to separate a converted fraction in a gaseous state called a light fraction and an unconverted liquid fraction containing solids called a residual fraction . This separation section preferably operates in conditions close to the operating conditions in the reactor, which are usually the following: pressure from 2 to 35 MPa with a preferred pressure of 10 to 25 MPa, and the partial pressure of hydrogen varies from 2 to 35 MPa, preferably from 10 up to 25 MPa, and the temperature is in the range from 300 ° C to 500 ° C, preferably from 380 ° C to 460 ° C. The residence time of the stream in this separation section is from 0.5 to 60 minutes, preferably from 1 to 5 minutes. The light fraction contains in the vast majority of compounds boiling at temperatures above 300 ° C, even 400 ° C or 500 ° C; they correspond to compounds present in gases, naphtha, light gas oil, and even heavy gas oil. It should be noted that this fraction contains the vast majority of these compounds, since the separation is not carried out in accordance with a specific cut-off point, it is usually carried out by equilibrium flash distillation. If it were required to speak in terms of the cut-off point, then we can say that it is in the range from 200 ° to 400 °, even 450 ° C.

Recycling of the light fraction is not an object of the present invention, and these methods are well known to those skilled in the art. The light fraction obtained after separation can be sent to at least one stage of hydrotreating and / or hydrocracking, and the goal is to bring different shoulder straps to meet technical requirements (sulfur content, soot formation point, cetane number, aromatic content, etc.). The light fraction can also be mixed with other raw materials before being sent to the hydrotreating and / or hydrocracking section. Before hydrotreating and / or hydrocracking, an external fraction can be added, usually coming from another process carried out at the refinery or optionally outside the refinery, preferably the external fraction is, for example, VGO (vacuum gas oil) from crude oil fractionation (straight run VGO), VGO from conversion, LCO (light recycle gas oil) or HCO (heavy recycle gas oil) from FCC (cracking with a fluidized catalyst).

Typically, hydrotreating and / or hydrocracking after hydroconversion can be carried out traditionally through the classic intermediate separation section (with pressure reduction) used after the high pressure and high temperature separator, for example, in the high pressure and low temperature separator, and / or by distillation at atmospheric pressure and / or vacuum distillation. Preferably, the hydrotreating and / or hydrocracking section is directly integrated into the intermediate hydroconversion section without pressure reduction. In this case, the light fraction is sent immediately, without additional separation steps and without pressure reduction, to the hydrotreating and / or hydrocracking section. This last embodiment makes it possible to optimize pressure and temperature conditions, dispense with additional compressors and, as a result, minimize the cost of additional equipment.

The residual fraction obtained after separation (for example, in an HPHT separator) and containing metals and a fraction of solid particles, used as an optional additive and / or formed during the reaction, can be sent to the fractionation step. This fractionation is an optional step and includes vacuum separation, for example, one or more cubes of instant distillation and / or, preferably, vacuum distillation, making it possible to concentrate the metal-rich vacuum distillation residue at the bottom of the cube or column and take one or multiple product streams. Preferably, the residual fraction obtained from the separation step without pressure reduction is separated by vacuum distillation into at least one fraction of the vacuum distillate and the fraction of the vacuum distillation residue, with at least a portion, preferably, all of the indicated fraction of the vacuum distillation residue being sent to the extraction step liquid-liquid, and at least a portion, preferably all of said vacuum distillate fraction, is preferably subjected to at least one hydrotreating step and / or hydrocracking.

The resulting liquid stream or the vacuum distillate fraction stream (s) are typically sent (a small fraction) to a suspended catalyst hydroconversion unit, where the distillate can be returned directly to the reaction zone, or it can then be used to prepare catalyst precursors before being introduced into the feed. The other part of the stream or streams is sent to the hydrotreating and / or hydrocracking section, optionally in a mixture with other fractions, such as, for example, the light fraction leaving the HPHT separator or the vacuum distillate coming from another installation, in equal or different proportions depending on quality of the products received. The purpose of vacuum distillation is to increase the yield of liquid streams for subsequent hydrotreating and / or hydrocracking and, thus, increasing the yield of base fuel. At the same time, the amount of residual fraction containing metals is reduced, which facilitates the concentration of metals.

Liquid / Liquid Extraction

The residual fraction obtained by separation without pressure reduction (for example, in an HPHT separator) and / or the vacuum distillation fraction from the vacuum separation (for example, taken from the bottom of the vacuum distillation column) then goes to the liquid / liquid extraction stage. The aim of this stage is to concentrate the metals in the effluent for further processing by burning, reducing its amount, and maximize the yield of liquid streams for their processing through hydrotreating and / or hydrocracking.

The extraction is carried out at high temperature and with a solvent of aromatic and / or naphthenoaromatic and / or polar type, alone or in a mixture, in equal or different proportions, said solvents preferably having high boiling points. Liquid / liquid extraction can be carried out in a decanter or in an extraction column. This extraction is distinguished by deasphalting known in the art by using aromatic and / or naphthenoaromatic and / or polar solvents, which provide better separation of insoluble compounds (containing metals) as compared to paraffin solvents, as well as using a higher extraction temperature necessary for retention of the fraction in the liquid phase.

The extraction step may be carried out in one step or, preferably, in two steps.

According to a one-stage liquid / liquid extraction embodiment, the operating conditions are usually as follows: solvent / feed ratio from 0.5 / 1 to 20/1, preferably from 1/1 to 5/1, temperature profile from 50 ° C to 350 ° C, preferably from 150 ° C to 300 ° C. The solvent used in the case of one-stage extraction is preferably aromatic and / or naphthenoaromatic and / or polar. As an aromatic solvent, you can use toluene, xylene, a mixture of BTX, phenol, cresols or their methyl derivatives, or a mixture of these solvents, or a diaromatic solvent, such as alpha-methylnaphthalene, as well as fractions rich in aromatics, such as LCO, HCO, aromatic extracts or a fraction of GO or heavy GO, individually or in a mixture, in equal or different proportions. The solvent can also come directly from this process or from any other oil refining process, such as catalytic cracking in a fluidized bed (solvent type LCO / HCO) or aromatics extraction units from lubricating oil production lines. As a naphthenoaromatic solvent, tetraline, indane, indene or a mixture of these solvents, as well as GO or heavy GO fractions from this process or from any other oil refining process, individually or in a mixture, in equal or different proportions, can be used. As a polar solvent, furfural, NMP (N-methyl-2-pyrrolidone), sulfolane, DMF (dimethylformamide), quinolein, THF (tetrahydrofuran) or a mixture of these solvents in equal or different proportions can be used.

It is necessary to choose a solvent having a sufficiently high boiling point so that the residual fraction leaving the HPHT separator and / or the vacuum distillation residue can be converted into liquid without evaporation, the residual fraction and / or the vacuum distillation residue usually being transferred to solution at temperatures in the range of 200 to 300 ° C. After the solvent contacts the residual fraction and / or the vacuum distillation residue, two phases are formed, the extract consisting of parts of the residue insoluble in the solvent (and having a high metal content), and the raffinate consists of the solvent and soluble parts of the residue. The solvent is separated from the soluble parts by distillation and recycled to a liquid / liquid extraction process; Solvent handling procedures are known to those skilled in the art.

At least a portion, preferably the entire soluble fraction, after distillation of the solvent, is preferably mixed with the heavy hydrocarbon fraction before the hydroconversion section on the suspended catalyst. A smaller portion can also be mixed with the light fraction from the HPHT separator for subsequent treatment by hydrotreating and / or hydrocracking.

According to a two-stage embodiment of the liquid / liquid extraction, the first extraction stage is carried out with a solvent of aromatic and / or naphthenoaromatic and / or polar type, then it is directed to the second stage of extraction with a paraffin type solvent. In the case of two-stage liquid / liquid extraction, the first extraction stage is strictly identical to the one-stage extraction described above. After the aromatic and / or naphthenoaromatic and / or polar solvent contacts the residual fraction and / or the vacuum distillation residue, two phases are formed, the extract consisting of parts of the residue which are insoluble in the solvent (and having a high metal content), and the raffinate consists of a solvent and soluble parts of the residue. This soluble phase after distillation of the solvent is directed to the second liquid-liquid extraction stage. This extraction is carried out with a paraffin type solvent, such as propane, butane, pentane, hexane, heptane, light naphtha from the present process (for example, after hydrotreating and / or hydrocracking) or from any other oil refining process, with one or in a mixture, equal to or different proportions. Operating conditions are usually as follows: solvent / feed ratio from 1/1 to 10/1, preferably from 2/1 to 7/1, temperature profile in the range from 50 ° C to 300 ° C, preferably from 120 ° C to 250 ° C, depending on the solvent in question. After contact with a paraffin solvent, two phases form. The extract consists of solvent-insoluble residue containing highly polar resins and asphaltenes, and the raffinate contains soluble parts that do not have or have very few asphaltenes. Due to the low concentration of asphaltenes in them, at least part of the raffinate, preferably all raffinate, can be mixed after separation of the solvent with a light fraction from the HPHT separator for treatment by hydrotreating and / or hydrocracking.

At least part of the fraction, preferably the entire extract, containing highly polar resins and asphaltenes, is preferably returned to the initial cycle of the hydroconversion section on the suspended catalyst.

Thus, the two-stage liquid / liquid extraction makes it possible, due to the choice of different solvents, to separate the raffinate from the first extraction stage into a fraction containing less asphaltenes and therefore suitable for direct treatment by hydrotreating and / or hydrocracking (i.e., to optimize the method with respect to the yield of base fuel), and a fraction containing more asphaltenes, which is preferably required to be returned to the slurry reactor.

Burning

The extract obtained as a result of a single-stage liquid / liquid extraction or after the first stage of a two-stage extraction has a high metal content. This extract is sent to the stage of burning at a moderate temperature. Indeed, in order to be able to extract metals by classical metal extraction methods, it is first necessary to carry out a preliminary step in order to separate the organic phase from the inorganic phase containing metals. Thus, the purpose of the combustion step is to obtain slags containing metals that are easily recoverable in subsequent metal recovery plants by burning the organic phase or carbon phase of the extract at temperature and pressure, which limit the evaporation and / or sublimation of metals, in particular molybdenum (sublimation temperature is approximately 700 ° C for MoO ₃ ). Thus, the stage of decreasing the content of the organic phase consists in burning at a moderate temperature in order to concentrate the metals without a noticeable loss of evaporation and / or sublimation into flue gases, in the inorganic phase, which may have an organic phase fraction of from 0 to 100% by weight, preferably , from 0% of the mass. up to 40% of the mass. The operating conditions at this stage of combustion are usually the following: pressure from -0.1 to 1 MPa, preferably from -0.1 to 0.5 MPa, temperature from 200 to 700 ° C, preferably from 400 to 550 ° C. Burning is carried out in the presence of air.

The gas stream leaving the combustion requires purification to reduce emissions of sulfur and nitrogen compounds into the atmosphere. The methods classically used by specialists in the field of air purification use the working conditions necessary to meet current standards in countries using such processing of hydrocarbon raw materials.

The solid phase obtained after combustion is an inorganic phase containing all or substantially all of the metals contained in the extract, in the form of slags.

Direct treatment of the extract from liquid / liquid extraction by a metal extraction method without burning, as described below, results in insufficient metal recovery.

Metal recovery

Slag obtained during combustion is sent to the stage of metal extraction, where the metals are separated from each other for one or more substages. This metal recovery is necessary since a simple return of the slag to the hydroconversion stage reveals a very low catalytic activity. Typically, the metal extraction step makes it possible to obtain several product streams, each stream containing a particular metal, for example, Mo, Ni or V, usually in the form of a salt or oxide. Each stream containing the catalyst metal is directed to the stage of preparing an aqueous or organic solution based on a metal identical to the catalyst or its precursor used in the hydroconversion stage. An effluent containing metal released from a feed that cannot be used as a catalyst (such as vanadium) can be used outside this process.

The operating conditions, fluids and / or extraction methods used for various metals are considered to be well-known to those skilled in the art and are already used in industry as described, for example, in Marafi et al ., Resources, Conservation and Recycling 53 (2008) 1- 26, US 4432949, US 4514369, US 4544533, US 4670229 or US 2007/0025899. Various known methods of metal extraction typically include washing with solutions of acids and / or bases, ammonia or ammonium salts, bio-washing with microorganisms, heat treatment at low temperature (firing) with sodium or potassium salts, chlorination or electrolysis of metals. Acid washing can be carried out with inorganic acids (HCl, H ₂ SO ₄ , HNO ₃ ) or organic acids (oxalic acid, lactic acid, citric acid, glycolic acid, phthalic acid, malonic acid, succinic acid, salicylic acid, tartaric acid, etc. d.). For washing with bases, ammonia, ammonium salts, sodium hydroxide or Na ₂ CO ₃ are usually used. In both cases, oxidizing agents (H ₂ O ₂ , Fe (NO ₃ ) ₃ , Al (NO ₃ ) ₃ , etc.) may be present to facilitate extraction. After dissolution of metals, they can be distinguished by selective precipitation (at different pH and / or with different agents) and / or extracting substances (oximes, beta-diketone, etc.).

Preferably, the metal extraction step of the present invention comprises washing with at least one acidic and / or basic solution.

Preparation of catalytic solutions

Metals recovered after extraction are usually in the form of a salt or oxide. The preparation of catalytic solutions for the preparation of organic or aqueous solutions is known to the person skilled in the art and is described in the Hydroconversion section. The preparation of catalytic solutions relates, in particular, to molybdenum and nickel metals, but vanadium, usually reused as vanadium pentoxide or in combination with iron to produce ferrovanadium, does not apply to this method.

The recovery of metals reused as a catalyst for the hydroconversion process on a suspended catalyst, or in the case of vanadium, is at least 50% by weight, preferably at least 65% by weight. and more preferably 70% of the mass.

Description of figures

The following figures represent preferred embodiments of the invention. Described mainly installation and method of the present invention. The operating conditions described above are not reiterated.

Figure 1 shows a method of hydroconversion of heavy oil fractions, including slurry technology without metal recovery.

Figure 2 describes a method for hydroconversion of heavy oil fractions of the present invention, including the extraction of liquid / liquid in one stage.

Figure 3 describes a method for the hydroconversion of heavy oil fractions of the present invention, comprising liquid / liquid extraction in two stages.

In Fig. 1, feedstock 1 is fed to the catalytic hydroconversion section A on a suspended catalyst. This suspended catalyst catalytic hydroconversion section consists of a heating furnace for feedstock 1 and hydrogen 2 and a reaction section consisting of one or more reactors arranged in series and / or in parallel, depending on the required capacity. Catalyst 4 or its precursor is also introduced, as well as optional additive 3. Catalyst 4 is held in suspension in the reactor and moves from bottom to top of the reactor together with the feed and is discharged with the product stream. The hydroconversion stream 5 is sent to separation section B at high pressure and high temperature, which makes it possible to separate the converted fraction 6 in the gaseous state, called the light fraction, and the unconverted residual liquid / solid fraction 8. The light fraction 6 can be sent to the section C hydrotreating and / or hydrocracking. At the beginning of hydrotreating and / or hydrocracking, an external fraction 7, usually obtained from another process available at the refinery or optionally outside the refinery, can be fed. The unconverted residual fraction 8 containing the catalyst and the solid fraction used as an optional additive and / or formed during the reaction is sent to fractionation step D. The fractionation step D is preferably vacuum distillation, which makes it possible to concentrate the metal-rich vacuum distillation residue 10 at the bottom of the column and to extract one or more streams 9 in the column head. In the heavy fraction valorization scheme using the conventionally used hydroconversion method on a suspended catalyst, the vacuum residue distillation 10, enriched with metals, reused as fuel with a very high viscosity or as solid fuel after gran lyatsii, for example, to provide heat and electricity locally or outside the installation or as fuel in cement plants. A priori, metals are not extracted. The resulting effluent or streams 9 thus obtained are usually sent via line 24 (a small part) to a suspended catalyst hydroconversion unit A , where the stream can be directly recycled to the reaction zone or can be used to prepare catalyst precursors before entering the feed 1, and another a portion is sent via line 25 to a hydrotreating and / or hydrocracking unit C in a mixture with streams 6 and / or 7, in equal or different proportions depending on the quality of the products obtained.

In FIG. 2, the stages (and references) of hydroconversion, separation of HPHT, hydrotreating and / or hydrocracking and vacuum distillation are the same as in FIG. The remainder of the vacuum distillation 10, taken at the bottom of the vacuum distillation unit D, is sent to a liquid / liquid extraction step E to concentrate the stream 10. This extraction step E is carried out in one step and carried out using an aromatic and / or naphthenic aromatic solvent 11, and / or polar type. The raffinate 12 exiting the extraction unit, after evaporation of the solvent, is preferably mixed in line 27 with hydrocarbon feed 1 before the hydroconversion section A on the suspended catalyst, or mixed in line 28 with stream 6 and / or 7 before the hydrotreating and / or hydrocracking section C. The high metal content extract 13 is sent to stage F of the reduction of the organic phase by burning at a moderate temperature, for a very strong concentration of metals, without noticeable loss of evaporation and / or sublimation into flue gases. The gas stream 14 from the combustion requires purification steps (not shown) to reduce emissions of sulfur and nitrogen compounds into the atmosphere. Product 15 obtained by burning F is an inorganic phase containing all or substantially all of the metals contained in extract 13, in the form of slags. The product 15 described above enters the metal extraction stage G , in which the metals are separated from each other in one or more stages. Stream 16 exiting extraction G consists of a metal such as molybdenum in the form of a salt or oxide. This stream 16 is then directed to a step H for preparing an organic or aqueous molybdenum-based solution 18 identical to the catalyst 4 or its precursor, which is recirculated through line 40, partially or completely, to the hydroconversion stage A on the suspended catalyst. Stream 17 exiting extraction G consists of a metal such as nickel in the form of a salt or oxide. This stream 17 is then sent to stage I of the preparation of an organic or aqueous solution 19 based on nickel identical to catalyst 4 or its precursor, which is partially or completely recycled to stage A of the hydroconversion on the suspended catalyst through line 41. Stream 20 leaving extraction G consists of from a metal such as vanadium in the form of a salt or oxide. This stream 20 can be reused, for example, in the form of vanadium pentoxide or in combination with iron, to obtain ferrovanadium.

In Fig. 3, the stages (and positions for reference) of hydroconversion, separation of HPHT, hydrotreating and / or hydrocracking and vacuum distillation are identical to those shown in Fig. 1. The residue of vacuum distillation 10 withdrawn from the bottom of the vacuum distillation D, is directed to step E1 extraction liquid / liquid, for concentrating the vacuum residue 10. According to this embodiment, the extraction step is carried out in two stages E1 and E2. The first step E1 is carried out with a solvent 11, preferably aromatic and / or naphthenoaromatic and / or polar. The raffinate 12 enters the second stage E2 liquid-liquid extraction. Stage E2 is carried out with a solvent of 21 paraffin type. The raffinate 22, leaving the second extraction stage and not containing asphaltenes, can then be mixed along line 30 with stream 6 and / or 7 before the hydrotreating and / or hydrocracking section C , while extract 23 containing highly polar resins and asphaltenes is recycled through the line 32 to the suspended hydroconversion section A , mixed with feed 1. Extract 13, leaving the first liquid-liquid extraction stage E1 and having a high metal content, is sent to stage F of reducing the organic phase by burning at low temperature, for very strong concentration of metals, without a noticeable loss of evaporation and / or sublimation into flue gases. The gas stream 14 from the combustion requires purification steps (not shown) to reduce emissions of sulfur and nitrogen compounds into the atmosphere. Product 15 obtained by burning F is an inorganic phase containing all or substantially all of the metals contained in extract 13, in the form of slags. The product 15 described above enters the metal extraction stage G , in which the metals are separated from each other in one or more stages. Stream 16 exiting extraction G consists of a metal such as molybdenum in the form of a salt or oxide. This stream 16 is then directed to stage H for the preparation of an organic or aqueous solution of molybdenum 18 identical to catalyst 4 or its precursor, which is partially or completely recycled to stage A of the hydroconversion on the suspended catalyst through line 40. Stream 17 leaving extraction G consists of from a metal such as nickel in the form of a salt or oxide. This stream 17 then passes to stage I of the preparation of an organic or aqueous solution 19 of nickel, identical to catalyst 4 or its precursor, which is partially or completely recycled to stage A of the hydroconversion on the suspended catalyst through line 41. Stream 20 leaving extraction G consists of from a metal such as vanadium in the form of a salt or oxide.

Preferably, the suspended catalyst hydroconversion using a molybdenum and nickel-based catalyst is carried out under hydrogen pressure on a finely dispersed catalyst such as nickel and molybdenum at a concentration of respectively 160 ppm. and 600 ppm Considering that an industrial installation has a capacity of 50,000 barrels per day and a degree of exploitation of 90% per year, it turns out that the amount of nickel and molybdenum consumed per year is 0.4 and 1.6 ct / year, respectively. Taking the cost of nickel of 25 thousand dollars per ton and molybdenum of 60 thousand dollars per ton, which represents the average cost observed on the market over the past 5 years, we get that operating costs are equal to 100 million dollars a year.

The method of the present invention makes it possible to reuse most of the metals: nickel and molybdenum present in the unreacted fraction of the stream exiting the hydroconversion on the suspended catalyst. The recovery of metals reused as a catalyst for the hydroconversion process on a suspended catalyst is at least 50% by weight, preferably at least 65% by weight, and more preferably 70% by weight. Thus, metal recycling makes it possible to reduce operating costs from $ 100 million per year to $ 30 million per year. Thus, the resulting savings is $ 70 million and makes it possible to first pay for the additional investments necessary to extract these metals. On the other hand, vanadium present in the heavy fraction in an amount of 400 ppm can be reused as ferrovanadium. Taking the degree of extraction of at least 50 wt. -%, preferably at least 65 wt. -%, and more preferably 70 wt. -%, the sale of vanadium can be estimated by taking the average cost observed in the metal market over the past five years, 40 thousand dollars per ton, at 12 million dollars a year. This sale will also allow for the first time to pay the additional investments necessary to extract these metals.

Extraction of these metals from the residual unreacted fraction makes it possible to reduce the total amount of spent nickel and molybdenum and, consequently, to reduce the environmental impact of the hydroconversion process on the suspended catalyst. Taking the degree of extraction of metals available at the inlet of the reaction zone as 70% by mass, it is obtained that the amount of auxiliary catalyst is reduced to 0.1 t / g. for nickel and 0.5 t / g. for molybdenum, compared with 0.4 t / g. and 1.6 t / g. without recycling.

Claims (13)

1. The method of hydroconversion of a heavy oil fraction containing metals fraction, including:
a) the step of hydroconversion of the feed in at least one reactor containing a suspended catalyst containing at least one catalyst metal and optionally a solid additive,
b) a step for separating the hydroconversion products without reducing the pressure, to obtain a fraction called light, containing compounds boiling at a temperature not exceeding 500 ° C, and a residual fraction,
b ′) optionally a fractionation step comprising vacuum separating said residual fraction obtained in step b) to obtain a high metal content vacuum distillation residue,
c) a liquid / liquid extraction step of the indicated residual fraction obtained in step b) and / or the indicated vacuum distillation residue obtained in step b ′), at a temperature in the range of 50 to 350 ° C. aromatic and / or naphthenic-aromatic , and / or a polar solvent, to obtain an extract with a high content of metal fractions, metal catalyst and raffinate,
d) a step of burning said extract at a temperature in the range from 200 to 700 ° C, to obtain slag with a high content of metal fractions and catalyst metal,
e) a step for extracting the metals of the fraction and the metal of the catalyst from slag obtained in the burning step,
f) a step for producing a solution or solutions of a metal or metals containing at least a catalyst metal that are recycled as a catalyst to a hydroconversion step a),
in which the specified fraction, called light, obtained in stage b), is subjected to at least one stage of hydrotreating and / or hydrocracking. 2. The method of claim 1, wherein the liquid / liquid extraction step is carried out at a temperature in the range of 150 ° to 350 ° C. 3. The method according to any one of the preceding paragraphs, in which the stage of extraction of the liquid / liquid is carried out at a ratio of solvent / raw material from 0.5 / 1 to 20/1, preferably from 1/1 to 5/1. 4. The method according to claim 1 or 2, in which the raffinate obtained in the liquid / liquid extraction step is subjected to a second liquid / liquid extraction step with a paraffin solvent at a temperature of from 50 to 300 ° C. 5. The method according to the preceding paragraph, in which the second stage of extraction of the liquid / liquid is carried out at a ratio of solvent / raw material from 1/1 to 10/1, preferably from 2/1 to 7/1, and at a temperature in the range from 50 to 300 ° C, preferably from 120 to 250 ° C. 6. The method according to p. 1 or 2, in which the specified residual fraction obtained in the separation stage without pressure reduction, is subjected to vacuum distillation, to obtain at least one fraction of a vacuum distillate and one fraction of a residue of vacuum distillation, and at least a portion, preferably all of the indicated fraction of the vacuum distillation residue enters the liquid / liquid extraction step, and at least a portion, preferably all of the specified fraction of the vacuum distillate, enters at least one hydro cleaning and / or hydrocracking. 7. The method according to p. 1 or 2, in which the stage of combustion is carried out at a pressure of from -0.1 to 1 MPa, preferably from -0.1 to 0.5 MPa, and at a temperature of from 200 to 700 ° C, preferably from 400 to 550 ° C, in the presence of air. 8. The method according to p. 1 or 2, in which the stage of metal extraction includes washing with at least one acidic and / or basic solution. 9. The method according to p. 1 or 2, in which the heavy oil fraction is a hydrocarbon fraction containing at least 50% wt. a product boiling at a temperature of more than 250 ° C, and at least 25% wt., boiling at a temperature of more than 350 ° C, and contains at least 50 ppm metals, at least 0.5% wt. sulfur and at least 1% wt. asphaltenes (heptane asphaltenes). 10. The method according to p. 1 or 2, in which the heavy oil fraction is selected from oil residues, crude oil, oil with the selected lightest fractions, deasphalted oils, asphalts after deasphalting isolated from the conversion of oil, tar sands or their derivatives, tar tails or their derivatives or mixtures of such raw materials. 11. The method according to p. 1 or 2, in which the hydroconversion stage is carried out at a pressure of from 2 to 35 MPa, preferably from 10 to 25 MPa, a partial pressure of hydrogen from 2 to 35 MPa, preferably from 10 to 25 MPa, a temperature in the range from 300 ° C to 500 ° C, preferably from 420 ° C to 480 ° C, and contact time from 0.1 h to 10 h, preferably from 0.5 h to 5 hours 12. The method according to p. 1 or 2, in which the suspended catalyst is a sulfonated catalyst containing at least one element selected from the group consisting of Mo, Fe, Ni, W, Co, V, Ru. 13. The method according to p. 1 or 2, in which the additive is selected from the group consisting of mineral oxides, spent supported catalysts containing at least one element of group VIII and / or at least one element of group VIB, low carb carbides hydrogen or from mixtures of such additives, wherein said additive has a particle size of less than 1 mm.

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