FR2885134A1 - PROCESS FOR PREFINING RAW OIL WITH MODERATE HYDROCONVERSION IN SEVERAL STEPS OF VIRGIN ASPHALT IN THE PRESENCE OF DILUENT - Google Patents

Abstract

Process for pre-refining a crude oil P in which P is fractionated into several fractions, typically hydrotreated, hydrocracked, or hydroconverted, and then these fractions are recomposed and generally at least 2 pre-refined oils Pa, Pc, Pa being a high quality non-asphaltenic oil, and Pc being a residual oil.The process typically comprises at least one initial distillation and a deasphalting SDA with a solvent of molecular weight at least 50 to separate a deasphalted oil DAO of virgin asphalt stream AS. AS is hydroconverted in at least 2 reactors in series bubbling bed, with a moderate conversion of less than 56%, typically in admixture with a virgin diluent comprising light fractions. DAO is typically hydrocracked with limited conversion of less than 80%.

Description

Field of the invention

  The present invention relates to the petroleum industry, and the use of sulfur heavy refinery residues. Petroleum is traditionally processed in an oil refinery by a set of fractionation and chemical conversion operations to produce a set of commercial end products that meet specific technical standards or specifications, eg distillation intervals, sulfur contents , characteristic technical indices such as the octane number or the diesel index, etc ...

  The main commercial end products are petrochemical naphtha, gasoline, kerosene, diesel (also known as diesel fuel), domestic fuel oil, as well as various categories of more or less sulfur-containing fuel oils, road asphalts and liquefied petroleum gases. , and sometimes other products: lubricating oils, solvents, paraffin, fuel for a gas turbine, etc ... An oil refinery produces a relatively large number of commercial end products, from a number of crude oils , chosen according to their composition and their price.

  The evolution of the markets on the one hand, in particular the increasing competition of natural gas, and specifications on the discharges of combustion plants on the other hand (releases of oxides of sulfur, oxides of nitrogen, particles particularly in Europe) lead to a significant disadvantage for heavy sulfur oil fuels, for example heavy fuel oil with no more than 3.5% or 4% sulfur. Refiners are therefore faced with a very important technical problem, that of the use of refinery sulfur residues, given the regulatory provisions. These sulfur fuels are typically surplus and many countries tend to limit the sulfur content of fuels to 1% sulfur and in the future to 0, 5% or even 0.3%.

  Another trend in the use of petroleum products is a tendency to increase the consumption of middle distillates and petrol to the detriment of fuel oil, the increase in consumption of middle distillates being more significant than that of gasoline.

  The invention relates to a process for the pre-refining of petroleum, typically in the production region, making it possible to obtain, as final products (pre-refining), one or more oils of improved quality. These (pre-refined) oils are typically removed, traded and transferred to refineries for refining.

  The Applicant has already proposed in the patent application FR-04 / 02.088 to use deposit gas, typically inexpensive, to pre-refine a conventional oil, and typically produce on the one hand a petroleum Pa to low sulfur content and substantially free of asphaltenes, and secondly a residual oil Pb (including starting asphaltenes, partly converted by a hydrogenating treatment). Pa oil produced will, after refining, very little or no sulfur fuel, and may have a high content of middle distillates increasingly demanded by the market. It is a high quality oil. The oil Pb typically comprises lower quality fractions, and in particular the residual asphaltenes.

  The process also plans to co-produce eventually commercial petroleum products: naphtha, diesel etc.

  This process of the prior art therefore produces a high quality oil Pa requested by the market. However, there remains a need to further improve the pre-refining process, including reducing the amount of Pb residual oil and / or the sulfur content of its heavy fractions, with low reaction volumes to reduce the investment of the unit of pre-refining. the market suitability and quality of the proposed high quality oil, to meet the needs of the market and increase the value of the proposed product.

  US Pat. No. 10 / 369,869 also discloses a very efficient process for converting residues separately converting pure asphalt (at 65% conversion) and unpaved oil at 90% conversion, in order to obtain overall conversion of the residue by almost 80% weight. This method describes a boiling bed hydroconversion process, typically with two reactors in series (figure and description of this figure). A process for hydroconversion of pure asphalt described in patent FR-2,396,065 is also known. The conversion to products boiling below 524 ° C (or vacuum distillate and lighter) is not known, and the The method described uses only one asphalt hydroconversion reactor.

  SUMMARY OF THE INVENTION The invention provides a conventional, generally conventional, crude oil pre-refining process for producing at least two pre-refined Pa and Pc oils, including Pa 3 2885134 which is a high quality, non-refined oil. asphaltenic (essentially free of asphaltenes), which will give after refining many high value products (naphtha, gasoline, middle distillates). On the contrary, Pc is a residual oil (having a residue containing asphaltenes), and will give after refining significant amounts of fuel.

  According to an essential characteristic of the invention, a bubbling bed conversion of a heavy asphaltenic ASF stream is carried out, which is typically a very high concentration stream of virgin asphaltenes. ASF generally comprises at least 40% and most often at least 50% by weight of virgin asphalt (the term virgin means that these are compounds derived directly from crude oil, which have not been cracked or hydrotreated).

  Unlike the prior art, it has surprisingly been found that a high conversion of asphalt (> 60%, for example 65% or more) was certainly possible and feasible, in particular by using at least two reactors in series. example, 2 or 3 or 4 reactors in series (or more), but that this extensive conversion, naturally sought after by the refiner as it is in line with market developments, was not desirable and that the marginal conversion to from about 56% conversion gives limited benefits in terms of increments of recoverable products and changes in the quality of products (including sulfur, nitrogen and metals in effluents), but requires additional reaction volumes and surprisingly high hydrogen consumption.

  In other words, it has been found that it is more advantageous, in a given reaction volume, to feed a significantly larger amount of feed, which results in a decrease in conversion and desulfurization (which are yet sought), but a sharp increase in the total amount of distillable products produced (less in concentration but more in quantity) as well as in the total amount of sulfur removed (in the form of H2S).

  It has also been found that it is advantageous to maintain at least 2 and preferably at least 3 series hydroconversion stages although the search for a relatively low conversion makes this option a priori not logical.

  It has also been found that it is more advantageous to carry out a treatment of the typically separated deasphalted oil with a notable hydrotreatment but a mean conversion and not of the order of 90%. According to one of the preferred characteristic variants of the invention, the residual DAO with a low sulfur content (significantly hydrotreated) is then available in sufficient quantity to both provide a low sulfur supplement to the effluent. hydroconversion of ASF (to compensate for its relatively high sulfur content), and on the other hand constitute one of the components of non-asphaltenic oil of high quality Pa.

  Finally, it was found that good hydroconversion results were obtained, and better hydrodynamic behavior of the first reactor, typically not requiring special management of gas fluidization conditions, if a suitable diluent was used to thin the reactor. the asphalt contained in ASF.

  Detailed description of the invention

  The invention proposes a process for the pre-refining of oil, making it possible to produce, from a crude oil P (or from several oils P1, P2, ...) at least 2 oils Pa and Pc, or even 3 pre-refined oils. Pa, Pb, Pc. Pa and Pb are typically high quality oils, i.e. oils substantially free of asphaltenes, while Pc is a residual oil comprising asphaltenes. The process may also possibly produce more than 3 pre-refined oils, for example 3 or more asphaltene-free oils. It can also produce 2 or 3 residual oils (containing asphaltenes) or more. Nor would it be beyond the scope of the invention if the process made it possible to co-produce final or refined products: fuel, naphtha, kerosene, diesel fuel, domestic fuel, oils or oil bases, etc.

  The crude oil (s) P is typically conventional, for example light Arabic, but any type of crude, conventional, heavy, asphaltic oil, and in particular any API oil ranging from 5 to 50 can also be used. .

  The process uses a fractionation of the oil P by at least initial distillation (so-called "atmospheric"), and generally vacuum distillation. The initial distillation preferably separates at least two fractions, one relatively richer in middle distillates and the other relatively richer in naphtha (or at least having different naphtha / middle distillate ratios).

  The process also typically comprises at least one HDT hydrotreating or conversion unit, in particular VGO vacuum distillate hydrocracking.

  It comprises a unit for deasphalting atmospheric residue or vacuum residue and a hydrotreating and / or hydrocracking unit for the DAO deasphalted oil produced.

  Finally, it comprises a hydroconversion unit of a very heavy load, ASF, comprising at least 50% by weight of virgin asphalt, and generally substantially no, or no non-virgin asphalt (already hydroconverted and recycled).

  In general, the invention provides a process for the pre-refining of at least one crude oil P, comprising: at least a first PRE-DIST initial distillation fractionation step F1 to produce a first asphaltenic residue R1 and at least one first (light) non-asphaltenic stream E1; at least a second fractionation step F2 of at least one part or fraction of R1 by deasphalting SDA with a hydrocarbon solvent of average molecular weight typically greater than 50, to produce at least: firstly a second non-asphaltenic stream E2; comprising at least 50% by weight of the virgin deasphalted oil included in the residue R1 (calculated as if all of the residue R1 was deasphalted under the same conditions), and secondly asphalt asphalt AS, in which is fed an ASF heavy asphaltenic current comprising at least 40% by weight, or at least 45% by weight, and typically at least 50% by weight of virgin asphalt AS (and typically at most 95%, or at most 90% virgin asphalt AS or of total asphalt in the case of recycling) in a RHDC unit for hydroconversion of ebullated bed residues comprising at least two stages of series hydroconversion in at least two reactors in series bubbling bed, the flow rate of current asphaltenic heavy being sufficiently high, and these two reactors being dimensioned according to this flow so that the conversion of the ASF load into products boiling below 524 C (by TBP distillation, as well as for all cutting points mentioned in the present application, unless otherwise indicated) is greater than 30% by weight but less than 56% by weight, to obtain an asphaltenic HAS hydroconversion effluent with a sulfur content of the non-distillable fraction at 524 C reduced compared with ASF, and at least one pre-refined asphaltenic Pc oil comprising at least a majority of the residual asphaltenes included in HAS is produced. The term "conversion of filler to products boiling below 524 C" refers to the percentage of these heavy products (524 C and over) that are converted into lighter products, compared to heavy products (524 C and above) initially contained in charge.

  All the cuts from P (typically with hydrotreatment or hydrocracking of the vacuum distillate VGO and optionally hydrotreatment of the middle distillates) can be combined in a single asphaltene residual oil Pc.

  However, preferably, from non-asphaltenic cuts from P, optionally after catalytic treatment (s) hydrogenating (s), at least one non-asphaltenic pre-refined oil Pa Pa is produced. These cuts can be hydrocracked and and / or hydroconverted and / or hydrotreated (each separately optionally being treated according to one of the possible variants of hydrogenating catalytic treatment, this term being explained later).

  ASF is a very heavy load: The solvent used is preferably relatively heavy (noticeably heavier than propane) and therefore produces asphalt concentrated asphaltenes. Suitable solvents include all mainly paraffinic (optionally olefinic) hydrocarbons having from 3 to 7 carbon atoms. But very preferably they include propane-butane mixtures, butane, pentane, hexane, heptane, light gasoline and mixtures obtained from the aforementioned solvents. Preferred solvents include butane, pentane, hexane and mixtures thereof. The most preferred solvents include butane, pentane and mixtures thereof.

  The operation of solvent deasphalting SDA can be carried out under conventional conditions: One can thus refer to the article by BILLON et al. Published in 1994 in volume 49, No. 5 of the review of the Institut Français du Pétrole P 495-507, the book "Refining and Conversion of Heavy Oil Products" by J.-F. Page, SG Chatila and M. Davidson, TECHNIP Editions, p 17-32, or to the description given in the patent FR-B-2 480 773 or in the patent FR-B-2 681 871 or in the patent application US Patent 4,715,946. The deasphalting can in particular be carried out at a temperature of between 60 ° C. and 250 ° C. with one of the abovementioned solvents, optionally supplemented with an additive.

  The solvents used and the additives are described in particular in the abovementioned documents and in patent documents US-A-1,948,296; US A2,081,473; US Patent 2,587,643; US Patent 2,882,219; US Pat. No. 3,278,415 and US Pat. No. 3,331,394. The solvent can be recovered by vaporization or distillation or by the opticritic process, that is to say under supercritical conditions. The deasphalting can be carried out in a mixer-settler or in an extraction column.

  As already mentioned, the hrc converting to ASF series bubbling beds is conducted relatively moderately, or even very low, for a multistage and series reactor process, by using a relatively high flow rate of charge and / or a relatively small reaction volume with respect to the feed rate.

  This allows, at the cost of a relatively low loss on the desired objectives (desulphurization in particular) to significantly reduce the reaction volume (therefore investment) and the consumption of hydrogen.

  The pressure used for the hydroconversion of the ASF current is typically between 12 and 26 MPa, in particular between 14 and 21 MPa. The temperature is typically between 340 ° C. and 460 ° C., most often between 390 ° C. and 450 ° C. It should be noted that gentle, but relatively severe operating conditions are not used, typically at a maximum control the reactions and avoid a rate of adverse side reactions (condensation) too high and too fast deactivation of the catalyst by coking. The conversion rate per reactor volume unit is therefore relatively high, and the final conversion is moderate only because the reaction volume is relatively low with respect to the ASF feed rate. The weight introduction rate of the charge per reaction stage (or reactor) is typically at least 0.54 h -1 or even at least 0.7 h -1 and most often at least 1 hr. , 08 hr or even at least 1.4 hr (expressed in kg / h of ASF feed fed to the reactor in question per kg of catalyst in the reactor). This weight speed is chosen sufficiently high for the conversion to be moderate and as desired. It is typically less than 5 hours, for example between 0.7 hours and 5 hours, especially between 1.08 hours and 4 hours, in particular between 4 hours and 3 hours. h- '.

  The unexpected behavior of the ASF feed that is very rich in virgin asphaltenes with respect to hydroconversion at high conversion levels could be explained in several ways, without linking the invention to any of these interpretations. : - On the one hand, after the initial cracking (and beyond conversions of about 50%), the pre-warped asphalt becomes more refractory. On the other hand the relative poverty of the DAO deasphalted oil charge (or the absence of DAO) means that the reaction medium no longer finds, contrary to a typical residue load (atmospheric or vacuum residue), compounds of the type of DAO likely to crack significantly, and to replace the asphalt to continue cracking.

  - On the other hand the absence or the small amount of these compounds of DAO, typically naphthenoaromatic does not provide a sufficient amount of hydrogen donors capturing the free radicals cracking. These hydrogen donors, present in the virgin asphalt, are increasingly rare after a conversion even quite limited. The reaction medium is therefore depleted of hydrogen-donor compounds capable of tempering the side reactions.

  Since the charge is very concentrated in heavy products, the harmful reactions of condensation of heavy polynuclear aromatics are therefore only slightly inhibited. This results in an unfavorable evolution of the yields, the quality of the products (sulfur, H / C ratio, nitrogen) and an increased tendency to deactivate the catalyst by coking.

  Thus it appears that the use of a virgin asphalt concentration in the hydroconversion charge, if it allows the use of small volume reactors for a given amount of asphaltenes (and crude oil), produces effects not expected at the level of hydroconversion.

  These effects are however largely neutralized according to the invention. The typical conversion of ASF feed into compounds boiling below 524 C (relative to the initial products boiling at least 524 C) is therefore according to the invention limited, generally at most 58% by weight, typically at most 56% weight (for example between 30% and 56% by weight) and generally at most 54% by weight (for example between 32% and 54% by weight). Preferred conversions are at most 52% by weight, or even at most 50% by weight or even at most 48% by weight or at most 46% by weight. The typical minimum conversion is about 30% by weight, or 32% by weight or 34% by weight. It may especially be used a conversion of between 34 and 52% by weight, in particular between 36 and 50% by weight. The minimum convention of 30% by weight should not be considered as a threshold or a favorable technical effect, but as a limit considered minimal for hydroconversion. Below this limit, it is considered that the charge is insufficiently transformed. On the other hand, one can not increase indefinitely the flow of load (which would lead to conversions below 30%) because the splitting investments then become predominant.

  The charge rate (or the volume of the reactors) is thus adjusted so that the conversion is in the desired range, taking into account the operating conditions. For a given reaction volume, an increase in the charge rate reduces the conversion.

  Very preferably, and although a low conversion is desired, ASF is hydroconverted in a RHDC residue hydroconversion unit comprising at least 3 hydroconversion steps in series in at least 3 ebullated bed reactors in series, for example 3 to 4 reactors in series. It has been found that for ASF charges with a high asphaltenes content according to the invention, the use of 2, 3 or 4 (or even more) stages and reactors in series makes it possible to effectively combat the loss of desulfurization performance resulting from the use of a low conversion. The average conversion per reactor to compounds boiling below 524 C is typically less than 28% by weight, often 22%, or 19% or even 17% by weight. The average conversion per reactor to compounds boiling below 340 C (gas oil and lighter compounds) is typically less than 15% by weight, often 12%, or 10% or even 8% by weight.

  According to one of the preferred variants of the invention, it is hydrotreated and / or hydrocracked and / or hydroconverted (HDC) E2 under a pressure of at least 8 MPa, with a conversion to products boiling below 52.degree. plus 80% by weight, to obtain an effluent comprising a significant fraction of hydrogenated deasphalted HDAO oil of sulfur content reduced by at least 50% with respect to the sulfur content of the HAS fraction (the hydroconversion effluent of ASF) boiling above 524 C, at least a majority of HAS is mixed with a stream comprising a first fraction F1 of this deasphalted hydrotreated oil HDAO to produce a (pre-refined) asphaltenic oil Pc and a second fraction F2 is mixed. of this HDAO hydrotreated deasphalted oil, optionally after complementary hydrotreatment, with other non asphaltenic streams derived from P, optionally hydrotreated and / or hydroconverted and / or hydrocracked to obtain a pre-refined non-asphaltenic oil Pa.

  The conversion of E2 is generally at most 75%, and preferably at most 70% or at most 60% or at most 50% by weight, to increase the amount of available residual dowel oil HDAO, and generally at least 40% (for example between 45% and 70% by weight). It can be conducted generally in a bubbling bed, typically at a significantly lower pressure than for the hydroconversion of ASF, and generally between 8 and 13 MPa. It is also possible to hydroconversion or hydrotreatment in a fixed bed under a similar pressure, or even to carry out an HDT hydrotreatment sequence in a fixed bed and then HDC hydroconversion in a bubbling bed, or the inverse HDC + HDT sequence.

  The weight introduction rate of the charge per reaction stage (or reactor) is typically at least 0.54 h -1 or even at least 0.7 h -1 and most often at least 1 hr. , 08 h. ' or even at least 1.4 h -1 (expressed in kg / h of feed E 2, or optionally added E 2 supplied to the reactor in question per kg of catalyst in the reactor). This weight speed is chosen sufficiently high for the conversion to be moderate and as desired. It is typically less than 12 hours, for example between 0.7 hours and 10 hours, especially between 1.08 hours and 6 hours, in particular between 4 hours and 5 hours. h- '.

  According to one of the preferred variants of the invention, the ASF heavy asphaltenic stream is not composed of pure asphalt but also comprises other lighter compounds. Typically ASF comprises at most 95% by weight or at most 90% by weight of virgin asphalt AS or total asphalt in case of recycling. Advantageously ASF comprises at least 10% or 2885134 at least 12%, or even at least 15% by weight (and generally less than 50%, or even less than 40% or 35% by weight) of compounds boiling below 524 C (typically virgin). or simply hydrotreated), for example by the presence or the addition of diluent diluent DIL substantially below 565 C, or even below 524 C. Preferably, ASF comprises, in addition to asphalt asphalt AS, at less a liquid DIL diluent at room temperature, and comprising at least 30% by weight of compounds derived from P boiling below 340 C.

  It has indeed been found that this presence or addition of a relatively light and fluid diluent had a favorable effect on the operation of the reactor, in particular on the first reactor, and all the more so as the number of reactors in series is high. (3 or more). The operation of the first reactor becomes more stable, more similar to that of the following reactors, and does not lead to seeking a specific fluidization (increased gas flow to obtain a turbulence intensity and homogeneity of the appropriate bubbling bed). The more stable and homogeneous operation leads to improved yields. With diluent DIL as defined above or below can even increase the conversion and operate up to 60% or even 62% conversion. More moderate conversions, however, remain interesting.

  DIL compounds are usually virgin or simply hydrotreated. More generally, they are typically derived from P, either virgin, or after hydrotreating, and / or hydrocracking, or after hydroconversion of DAO and / or VGO with or without prior or subsequent hydrotreatment. The only possible treatments are therefore catalytic hydrogenation treatments of the group consisting of HDT hydrotreating, HDC hydroconversions of typically non-asphaltenic feedstocks, HDK hydrocracking (mild, medium pressure or high pressure) and the combinations of these treatments.

  The use of such fractions for the diluent may be surprising: Indeed, these, for light fractions are very poor in naphthenoaramatic compounds or polyaromatic precursors naphthenoaramatiques desired by theory (such as those that can result in the reaction medium of the use of catalytic cracking fractions LCO / HCO (light / heavy cyclic oil) It is therefore believed that the observed beneficial effect results mainly from the effect of reducing the viscosity of the liquid in the reaction medium.

  Typically, the diluent DIL (for example essentially comprising fractions boiling below 565 C (distillable) or 524 C) represents between 3% and 40% by weight relative to the asphalt included in ASF. Generally, DIL comprises between 3% and 30% by weight, relative to the asphalt included in ASF, of fractions derived from virgin P or simply hydrotreated boiling below 340 C.

  According to one variant, DIL comprises a fraction of composition substantially identical to petroleum. DIL may in particular comprise, at a rate of 4% to 40% by weight relative to the asphalt included in ASF, a stream consisting essentially of desalinated P oil. This is interesting because it limits the amount of oil to be fractionated, this unfractionated oil being usefully converted.

  DIL could also include a desalted petroleum fraction (for example P freed of fractions C5 (or C6) and lighter or the fraction of P boiling above 150 C), in the same proportions as mentioned above. One could also use the mixture of middle distillates boiling mainly below 340 C and a fraction of P as mentioned above.

  According to the invention, Pa, Pc (and optionally Pb), are oils, end products of the pre-refining process each intended to be used as an initial distillation feedstock of one or more oil refineries: , Pc, (and Pb) are end products of the pre-refining process. But these are conventional oil refinery loads and not end products or intermediate refining products, or end products for direct use. They each typically comprise at least 6% by weight of naphtha N, at least 10% by weight of middle distillates MD (for example at least 4% by weight of kerosene] 170 C / 250 C] and at least 6% by weight of diesel cutter 250 C / 360 C]), and at least 10% by weight of vacuum distillate VGO.

  Generally, at least the majority of Pa and Pb are separately transported by pipelines and oil boats for use as initial distillation feeds of one or typically several oil refineries.

Description of Figure 1

  Referring now to Figure 1 which shows a non-limiting example of an installation scheme for carrying out the method according to the invention.

  A crude oil P, typically conventional (for example light arabic), is supplied by the line 1 in a desalter 2. The desalinated oil feeds via the line 3 a column 12 2885134 preliminary distillation PRE-DIST, referenced 4 ( often referred to as initial distillation or atmospheric distillation) typically operating at a pressure of between 0.1 and 0.5 MPa. This column, which can eventually produce a brief fractionation, produces a light stream, typically of naphtha and lighter compounds, through line 30, a middle distillate stream MD, typically kerosene and diesel cut through line 5, and a stream of intermediate gas oil IGO line 6, which may include fractions boiling mainly between 340 C and 420 C. This intermediate gas, relatively heavy for an atmospheric column can be obtained through a large stripping steam.

  Column 4 also produces an atmospheric residue via line 7, which feeds a VAC-DIST vacuum distillation column referenced 8. This column, which typically operates at a pressure of between 0.004 and 0.04 MPa, produces a distillate stream. VGO vacuum through line 10, and a vacuum residue stream VR through line 9. It can also optionally produce a LVGO light vacuum distillate stream through line 11.

  The vacuum residue VR is fed into a SDA unit referenced 12 of solvent deasphalting (preferably pentane) to produce a deasphalted oil DAO circulating in line 13 and a stream of asphalt AS discharged via line 14.

  The asphalt AS is mixed with a stream of diluent DIL fed through line 15. This stream typically comprises a desalinated petroleum stream fed from line 3 via line 15 and a middle distillate stream MD fed from the line 5 via line 22 and optionally an intermediate fuel gas stream IGO fed from line 6 via lines 23 and 22. DIL may also comprise naphtha N taken from line 30.

  Typically ASF comprises 20% by weight of diluent DIL with respect to virgin asphalt AS separated by deasphalting SDA and consists of the mixture of AS and DIL. A typical composition of DIL is, relative to AS: 10% weight of crude oil P desalted + 10% by weight of middle distillates boiling between 170 C and 340 C (or 360 C).

  The ASF mixture of virgin asphalt AS and diluent (fluxed asphalt) then feeds the hydroconversion unit RHDC boiling bed referenced 16. This unit typically comprises at least 2, and preferably at least 3 bubbling bed reactors arranged in series.

  At the output of the RHDC unit, the hydroconversion effluent is added by several currents flowing in the lines 30c, 31c, 32c, 33c, and 34c. These streams typically include naphtha N (line 30c), hydrotreated middle distillates MD (line 31c), hydrotreated or hydrocracked IGO intermediate gas (generally partially) (line 32c), hydrotreated or hydrocracked VGO vacuum distillate (generally partially) (line 33c), hydrotreated or hydrocracked deasphalted oil (usually partially) (line 34c). A (pre-refined) Pc oil is thus reconstituted from the hydroconversion effluent, which comprises unconverted asphaltenic fractions, and non-asphaltenic fractions that are typically hydrotreated or hydrocracked, and therefore have a reduced sulfur content. This Pc oil has a significantly lower sulfur content than that of the initial oil P. The fractions MD, IGO, VGO, DAO are then hydrotreated and / or hydrocracked (typically partially) in the units H1 referenced 21, H2 referenced 20, H3 referenced 19 and H4 referenced 18. Typically, H1 (and often H2) is a hydrotreatment HDT, and H3 and H4 are mild hydrocracking units: M-HDK, medium pressure: MPHDK, or high pressure: HP-HDK. Preferably, H4 is bubbling bed hydrocracking.

  The light current flowing in line 30 is subdivided into 3 elementary currents 30a, 30b, 30c.

  The effluent of H1 circulating in the line 31 is subdivided into 3 elementary currents 31a, 31b, 31c.

  The H2 effluent circulating in the line 32 is subdivided into 3 elementary currents 32a, 32b, 32c.

  The effluent of H3 circulating in the line 33 is subdivided into 3 elementary currents 33a, 33b, 33c.

  The effluent of H4 flowing in line 34 is subdivided into 3 elementary streams 34a, 34b, 34c.

  From the streams 30a, 31a, 32a, 33a, and 34a is formed by mixing a pre-refined oil Pa Pa is an oil substantially free of asphaltenes since each of its components is also (asphaltenes are only contained in the current AS). It is also a very low sulfur oil since most of its components are desulfurized, and naphtha, fed via line 30a, is typically low in sulfur (it can also be hydrotreated, optional).

  Similarly, from the streams 30b, 31b, 32b, 33b, and 34b, a pre-refined petroleum Pb is formed by mixing. For the same reasons as for Pa, Pb is also an oil substantially free of asphaltenes. at very low sulfur content.

  The conversions of the units and the distribution of the Pa and Pb components are advantageously determined so that Pa is relatively rich in gasoline and naphtha precursors, and relatively poor in middle distillates: kerosene and diesel cut while Pb, on the contrary, is an oil. relatively poorer in petrol precursors and naphtha, and relatively richer in middle distillates.

  The invention can therefore, before recomposing the oils Pa, Pb, Pc, implement one or more catalytic steps using certain methods well known in the state of the art, including desulfurizing treatments, under hydrogen pressure, which consume significant or high amounts of hydrogen.

  According to the invention will be called "hydrogenating catalytic treatment" a treatment comprising at least one of the treatments defined below and symbolized by the following names: HDT, HDC, HDK (which covers MHDK, MP-HDK and HP-HDK) , RHDT, HRSDC. A hydrogenating catalytic treatment may therefore comprise several of these treatments, for example HDT + HDC or HDC + HDT etc ...

  The following hydrogenation catalytic treatments are thus distinguished: a) Hydrotreatments (symbolically designated by the HDT siqle) of asphaltene-free feeds: Hydrotreatments of hydrocarbon distillates or deasphalted oil (fillers substantially free of asphaltenes) are well-known processes of the state of the art. Their main purpose is the at least partial elimination of undesirable compounds, typically sulfur, nitrogen, possibly metals such as iron, nickel or vanadium, etc. They are also often used for the hydrogenation of aromatics, usually simultaneously with the desulfurization of the feedstock.

  Conventionally, for those of the abovementioned fillers which comprise compounds boiling above 371 C, the term "hydrotreatment" refers to a process in which the conversion of these compounds to compounds with a boiling point below 371 C is less than or equal to 20% by weight. . For processes treating the same feedstocks, but with a conversion greater than 20% by weight, it will be called hydroconversion (symbolically designated by the acronym HDC), or hydrocracking (symbolically denoted HDK), these processes being presented below.

  2885134 Hydrotreatment processes operate under hydrogen pressure, and use supported solid catalysts, typically granular solids or feature-size extrudates (diameter for balls or equivalent diameter (corresponding to the same section) for extrudates) included between 0.4 and 5 mm, in particular between 1 and 3 mm, the operating conditions, and in particular the space velocity (VVH) and the molar ratio hydrogen on hydrocarbon (H2 / HC) vary according to the cuts treated, the impurities present and the final specifications sought.

  Typical and non-limiting examples of operating conditions are given in the following Table 10: Cup Point Speed Pressio Temperature Report Spatial Consumption n of H2 e start of H2 / HC n of H2 petroleum cut (h-1) (bar) cycle (C) (Nm3 / m3) (wt%) (C) Naphtha 70-180 4-10 5260-300 100 0.05-0.01 Kerosene 160-240 2-4 15-30 300-340 150 0, 01-0.02 Diesel and Gas oil 230-371 1-3 20-40 320-350 150-300 0.3-0.8 Vacuum gas oil 371-565 1-2 40-70 360-380 300-500 0, 4-0.9 Oil> 565 0.5-1.5 50110 360-380 500-1000 0.5-1 Deasphalted Hydrotreating catalysts typically comprise a metal, or a Group VIB metal compound and a metal or compound of a Group VIII metal, on a support.

  The most common catalysts are composed of an oxide carrier and an active phase in the form of molybdenum sulfide or tungsten promoted by cobalt or nickel. The commonly used formulas are the CoMo, NiMo and NiW combinations for the active phase, and the high surface area alumina for the support. The metal contents are often of the order of 9 to 15% by weight of molybdenum and 2.5 to 5% by weight of cobalt or nickel.

  Some of these catalytic formulas are sometimes doped with phosphorus. Other oxide supports are employed, such as mixed oxides of silica-alumina or titanium-alumina type.

  These carriers are typically of low acidity, to obtain acceptable catalytic cycle times.

  Typical examples of catalysts and hydrotreatment, particularly diesel, gasoil or gas oil cuts under vacuum are the catalysts HR448 and HR426 of the French company AXENS.

  When traces of metals, in particular nickel and vanadium, are present in the feedstock, a catalytic support comprising a porosity adapted to the deposition of these metals is advantageously used.

  An example of such a catalyst is HMC 841 from AXENS.

  For the hydrotreatment of a deasphalted oil (DAO) comprising metals, it will be possible, for example, to use a first bed with an HMC 841 catalyst, for the demetallization, then a second bed of HR 448 for the desulfurization and denitrogenation.

  Other technical elements relating to hydrotreating can be found in the reference work: "Conversion processes", P. Leprince, 15 Editions Technip, Paris 15th, pages 533-574.

  b) Hydrocracking Processes (Symbolically Required by the Abbreviation HDK) of Asphaltene-Free Loads: Hydrocracking processes are also methods well known in the state of the art. They apply exclusively to charges substantially free of asphaltenes or metals such as nickel or vanadium.

  The hydrocracking feedstock is typically composed of vacuum gas oil, sometimes supplemented with gas oil and / or deasphalted oil (deasphalted vacuum residue, typically with a solvent from the group formed by propane, butane, pentane and mixtures thereof, and preferably propane and butane).

  It is also possible to hydrocrack DAO deasphalted oil. The DAO must then be of sufficient quality: typically, a hydrocracking feedstock comprises less than 400 ppm (parts per million by weight) of asphaltenes, preferably less than 200 ppm and most preferably less than 100 ppm. The metal contents (typically nickel + vanadium) of a hydrocracking feedstock are typically less than 10 ppm, preferably less than 5 ppm, and most preferably less than 3 ppm.

  Conventionally, it is considered that a load is substantially without asphaltenes if its asphaltenes content is less than 400 ppm. (For a pre-refined oil, it is considered in a similar way that it is asphaltenes-free, or non-asphaltenic, if the fraction boiling above 524 C contains less than 400 ppm of asphaltenes).

  Typically the hydrocracking feedstock is first pre-refined on a hydrotreatment catalyst, typically different from the hydrocracking catalyst. This catalyst, typically of acidity lower than that of the hycrocracking catalyst, is chosen to substantially eliminate the metals, reduce the traces of asphaltenes, and reduce the organic nitrogen, which inhibits the hydrocracking reactions, to a value of typically less than 100 ppm, preferably 50 ppm and very preferably less than 20 ppm.

  Hydrocracking catalysts are typically bifunctional catalysts having a dual function: acid on the one hand and hydrogenating / dehydrogenating on the other hand. Typically, the support has a relatively high acidity such that the ratio of hydrogenating activity on isomerizing activity H / A as defined in French Patent No. 2,805,276 pages 1 line 24 to page 3 line 5, is greater than 8, or preferably greater than 10 or very preferably greater than 12, or even greater than 15. Typically, a hydrotreatment is carried out upstream of the reactor or the hydrocracking zone with a hydrotreatment catalyst whose aforementioned H / A ratio is less than 8, especially less than 7.

  The hydrocracking catalysts typically comprise at least one Group VIB metal or metal compound (such as Mo, W) and a metal or Group VIII metal compound (such as Ni ...) deposited on a support. The atomic ratio of the Group VIII metal (Mv ,,,) to the sum of the metals of Groups VIII and VI B, ie the atomic ratio Mv ,,, / (Mv ,,, + MV, B ), especially for the NiMo and NiW pairs, is often close to 0.25, for example between 0.22 and 0.28.

  The metal content is often between 10 and 30% by weight.

  The metal of group VIII may also be a noble metal such as palladium or platinum, at levels of the order of 0.5 to 1% by weight.

  The acidic support may comprise a halogen-doped alumina, or a silica-alumina having a sufficient acidity, or a zeolite, for example a dealuminated Y or USY zeolite, often having a double pore distribution with a double porosity network comprising in particular micropores of size mainly between 4 to 10 Å and mesopores of size mainly between 60 and 500Â. The silica / alumina ratio of the structure of the zeolite is often between 6.5 and 12. By way of example, it is possible to use a hydrotreatment and hydrocracking sequence with the catalysts HR 448 (HDT) and then HYC 642 (HDK) marketed by the French company AXENS. If the feedstock comprises metals, one can use upstream of these two catalytic beds a bed of demetallization catalyst such as the catalyst HMC 841 also marketed by AXENS.

  Examples of operating conditions for hydrocracking are typically: - space velocity VVH between 0.3 and 2 h -1, - temperature between 360 and 440 ° C., - recycling of hydrogen between 400 and 2000 Nm3 per cubic meter of charge, - Hydrogen partial pressure and total pressure can vary significantly depending on the charge and conversion desired. By convention, a conversion greater than or equal to 20% by weight and less than 42% by weight corresponds to a mild hydrocracking (symbolically denoted M-HDK); a conversion greater than or equal to 42% by weight and less than 60% by weight corresponds to a medium pressure hydrocracking (symbolically noted MPHDK); a conversion greater than or equal to 60% by weight (and typically less than 95% by weight corresponds to a high-pressure hydrocracking (symbolically denoted HP-HDK).

  By definition, the conversion is that of products with a boiling point greater than 371 C, products boiling below 371 C.

  Typically, the hydrogen partial pressure is, depending on the feedstock, often between about 2 MPa and 6 MPa for mild hydrocracking, between about 5 MPa and 10 MPa for medium pressure hydrocracking, and between about 9 MPa and 17 MPa. MPa for high pressure hydrocracking. The total pressure is often between 2.6 and 8 MPa for mild hydrocracking, between about 7 and 12 MPa for medium pressure hydrocracking, and between 12 and 20 MPa for high pressure hydrocracking.

  The hydrocracking processes are typically operated in a fixed bed with granular solids or extrudates of characteristic dimension (diameter for balls or equivalent diameter (corresponding to the same section) for extrusions) of between 0.4 and 5 mm, in particular between 1 and 3 mm. It would not be departing from the scope of the invention if the hydrocracking was carried out in a moving bed (granular catalyst bed typically in the form of extrudates or, preferably, beads, of dimensions similar to those described for a fixed bed.

  Other technical elements related to hydrocracking can be found in the reference book: "Hydrocracking Science and Technology", J Scherzer and AJ Gruia, Publisher Marcel Dekker, New York, and in the reference work: "Conversion processes", P. Leprince, Technip Publishing, Paris 15th, pages 334-364.

  (C) Hydroconversion processes (symbolically designated by the abbreviation HDC) of a charge without asphaltenes (for example of the DAO type) but comprising significant quantities of metals (Ni, V): Such processes are known for achieve conversions (with the same definition as for hydrocracking) greater than 20% by weight and often much higher (for example from 20% to 50%, or from 50% to 85% by weight, for example ebullated bed processes These processes may use variable hydrogen partial pressures, for example between 4 and 12 MPa, temperatures between 380 and 450 ° C., and hydrogen recycling for example between 300 and 1000 Nm3 per cubic meter of feedstock. are similar or similar to that of hydrotreating catalysts or hydroconversion of residues, defined below, and have a porosity to have a significant capacity for demetallization.

  One can for example use a catalyst of the HTS 358 type, marketed by the French company AXENS.

  d) Hydrotreatments of residues (symbolically designated by the RHDT symbol) or hydroconversions of residues (symbolically designated by the acronym RHDC): The processes of hydrotreatment of residues (and hydroconversion of residues are well known processes of the state of the technique.

  The operating conditions of these processes are typically: hourly space velocity (or VVH) of between 0.1 and 0.5. H2 partial pressure between 1 and 1.7 MPa. Hydrogen recycling between 600 and 1600 Nm3 per m3 of load. Temperature between 340 and 450 C. The catalysts of the fixed-bed, mobile or bubbling methods are most often supported macroscopic solids, for example beads or extrudates with a mean diameter of between 0.4 and 5 millimeters. Typically they are supported catalysts comprising a metal or metal compound of group VIB (Cr, Mo, W) and a metal or metal compound of group VIII (Fe, Co, Ni, ...) on a mineral support, by example catalysts based on cobalt and molybdenum on alumina, or nickel and molybdenum on alumina.

  For a hydrotreatment or a hydroconversion in a fixed bed, it is possible to use, for example, a hydrodemetallization catalyst HMC 841, and then hydroconversion and hydrocracking catalysts: HT 318 and then HT 328 marketed by the French company AXENS. For a bubbling bed, it is possible to use a catalyst of the HOC 458 type, also marketed by the French company AXENS.

  The catalysts for the slurry processes are more diverse and may include particles of ground coal or lignite impregnated with iron sulfate or other metals, ground spent hydrotreating catalyst, molybdenum sulfide particles associated with a matrix. hydrocarbon-based, obtained by in situ decomposition of precursors such as molybdenum naphthenate, etc. The particle sizes are typically less than 100 microns, or even much smaller.

  Other characteristics of the processes and catalysts for hydroconversion of residues are given in the general work referenced A: "Refining and conversion of heavy oil products", by JF Le Page, SG Chatila, M Davidson, Technip Publishing, Paris , 1990, in Chapter 4 (Catalytic Conversion under Hydrogen Pressure), and Chapter 3, paragraph 3.2.3. Reference may also be made to the general work referenced B: "Conversion processes", P. Leprince, Technip Publishing, Paris 15th, pages 411-450., In Chapter 13 (hydroconversion of residues), and and in the general work: "upgrading petroleum residues and heavy oils" which means improving the quality of petroleum residues and heavy oils, by Murray R. Gray, publisher Marcel Dekker inc. New York, Chapter 5.

  The production of hydrogen, for the implementation of these catalytic hydrogenation treatments can be carried out from purified gas for example by steam reforming on nickel catalyst and then conversion of CO to steam and purification is a well-known process, described in US Pat. book reference B cited above, p 451-502, or in the reference work: "The desulphurization of heavy oils and residua", J Speight, Publisher Marcel Dekker, Inc. New -York.

21 2885134

Claims (13)

  A process for pre-refining at least one crude oil P, comprising: at least a first PRE-DIST initial distillation fractionation step F1 to produce a first asphaltenic residue R1 and at least a first non-asphaltenic stream E1; at least one second fractionation step F2 of at least one part or fraction resulting from R1, by deasphalting SDA with a hydrocarbon solvent of average molecular weight greater than 50, to produce at least: firstly a second non-asphaltenic stream; E2 comprising at least 50% by weight of the virgin deasphalted oil included in the residue R1, and secondly of the virgin asphalt AS, in which a heavy asphaltenic stream ASF comprising at least 50% by weight of virgin asphalt is supplied; AS in a RHDC unit for hydroconversion of ebullated bed residues comprising at least two hydroconversion stages in series in at least two reactors in series bubbling bed, the heavy asphaltenic flow rate being sufficiently high, and these two reactors being dimensioned according to this flow rate so that the conversion of the ASF load into products boiling below 524 C is greater than 30% weight but less than 56% weight, to obtain an asphaltenic HAS hydroconversion effluent whose sulfur content of the non-distillable fraction at 524 C is reduced relative to ASF, and at least one pre-refined asphaltenic Pc oil comprising the major part is produced at least residual asphaltenes included in HAS.   2. Method according to claim 1 wherein from non-asphaltenic cuts from P, optionally after catalytic treatment (s) hydrogenating (s), at least one pre-refined non-asphaltenic oil Pa.   3. The process as claimed in claim 2, in which the hydrotreatment and / or hydrocracking and / or hydroconverting E2 are carried out under a pressure of at least 8 MPa, with a conversion to products boiling below 524 ° C. for at most 80% by weight, for obtaining an effluent HE2 comprising a significant fraction of hydrogenated deasphalted oil HDAO with a sulfur content reduced by at least 50% relative to the sulfur content of the HAS fraction boiling above 524 C, in particular mixing with at least the major part of HAS a stream comprising a first fraction F1 of this deasphalted oil hydrotreated HDAO to produce said pre-refined asphaltenic oil Pc and a second fraction F2 of this hydrotreated deasphalted oil HDAO is mixed, optionally after further hydrotreating, with d other non-asphaltenic streams from P, optionally hydrotreated and / or hydrocracked and / or hydroconverted to obtain said pre-raff oil non-asphaltenic iné Pa.   4. Method according to one of the preceding claims wherein ASF is hydroconverted in a hydroconversion unit of residues RHDC comprising at least 3 hydroconversion stages in series in at least 3 reactors in a series of bubbling beds.   5. Method according to one of claims 1 to 4 wherein the ASF heavy asphaltenic current comprises, in addition to virgin asphalt AS, at least one liquid DIL diluent at room temperature, and comprising at least 30% by weight of compounds derived from P boiling below 340 C.   The process of claim 5 wherein said DIL diluent is from 3% to 40% by weight based on asphalt included in ASF.   7 Process according to one of claims 5 and 6 wherein DIL comprises between 3% and 30% by weight, relative to the asphalt included in ASF, virgin fractions or simply hydrotreated from P, boiling below 340 C.   8. Method according to one of claims 5 and 6 wherein DIL comprises a virgin fraction derived from P and substantially identical composition of petroleum P. 9. A process according to claim 8 wherein DIL comprises at a rate of 4% to 40% by weight, based on the asphalt included in ASF, a stream consisting essentially of desalinated P oil.   23 2885134 10. The method of claim 3, wherein F1 is between 15% and 85% by weight of (F1 + F2).   11. The method according to one of the preceding claims wherein Pa and Pc, are two oils, each being a final product of the pre-refining for use as an initial distillation feed of one or more several petroleum refineries.   12. Method according to one of the preceding claims wherein is transported separately the greater part at least Pa and / or Pc by pipelines and oil boats for use as initial distillation charges of one or more refineries several of oil.   13. Process according to one of the preceding claims, in which Pa and Pc each comprise at least 6% by weight of naphtha N, at least 10% by weight of middle distillates MD, and at least 10% by weight of vacuum distillate VGO.