INTEGRATED METHOD FOR PRODUCING MIDDLE DISTILLATE WITH A RECYCLING LOOP IN HYDROTREATMENT

- IFP Energies Nouvelles

Method of treating petroleum feedstocks comprising the hydrotreatment of said feedstocks followed by hydrocracking of at least one part of the hydrotreatment effluent. Cooling and separating the hydrocracking effluent into a hydrogen-rich gas efflux and a liquid efflux. Fractionating the liquid effluent into converted hydrocarbon products having boiling points lower than 340° C. and an unconverted liquid fraction having a boiling point higher than 340° C. Hydrotreating a diesel-fuel-type liquid hydrocarbon feedstock and separating the effluent into a hydrogen-rich gas efflux and a liquid efflux. Fractionating the liquid efflux into at least one light gas fraction, a naphtha fraction, and a middle distillate fraction having a boiling point higher than 150° C. and compressing the gas efflux in a hydrogen makeup compressor supplying the hydrotreatment and hydrocracking steps comprising at least 2 stages, with said gas efflux being injected and compressed in an intermediate stage of said compressor before being recycled upstream.

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Description
FIELD OF THE INVENTION

This invention relates to a method for treatment of petroleum feedstocks whose objective is to maximize the quantity and the quality of middle distillate fractions that are produced.

The method for hydrocracking vacuum distillates or DSV is a key refining method that makes it possible to produce, from excess heavy feedstocks that cannot be readily upgraded, the lighter fractions such as gasolines, jet fuels, and light diesel fuels that the refiner strives to produce in order to adapt his production to demand. Certain hydrocracking methods make it possible also to obtain a highly purified residue that can constitute excellent bases for oils or an easily upgradable feedstock in a catalytic cracking unit, for example. One of the effluents that is particularly targeted by the hydrocracking method is the middle distillate (fraction that contains the diesel fuel fraction and the kerosene fraction). This catalytic method does not make it possible to transform the DSV in its entirety into light fractions. After fractionation, a more or less large proportion of an unconverted DSV fraction, referred to as UCO or UnConverted Oil according to English terminology, therefore remains. The conversion level and the selectivity of the method can be adjusted with the option of UCO recycling at the inlet of the hydrotreatment reactor or at the inlet of the hydrocracking reactor (so-called 1.5-step mode). The addition of a conversion reactor or hydrocracking reactor to the UCO recycling is another means to adjust the conversion and the selectivity (so-called 2-step mode).

The method for hydrodesulfurization of diesel fuels makes it possible to reduce the amount of sulfur contained in a diesel fuel fraction while minimizing the conversion of the feedstock into lighter products (gas, naphtha). The hydrodesulfurization feedstock can consist of straight-run diesel fuel according to English terminology or diesel fuel obtained from atmospheric fractionation of crude oil, the Light Vacuum Gasoil Oil according to English terminology or light vacuum distillate, the LCO or distillate obtained from a conversion method (FCC, coking . . . ), of a diesel fuel feedstock obtained from biomass conversion (esterification, for example), by themselves or in a mixture, for example.

The partial hydrogen pressure required for this method is lower than the partial hydrogen pressure in the hydrocracking device. It is common practice for these two methods to be present in the same refinery without being integrated. However, they are based on very similar method schemes, constituted by a feedstock furnace, fixed-bed reactors, hydrogen-recycling compressors, and more or less complex high-pressure separation sections.

This invention consists in integrating these two methods so as to reduce investment costs and energy expenditure of the middle distillate production complex. Inter-unit integration is based on a pooling of equipment.

Prior Art

The patent U.S. Pat. No. 7,507,325 B2 describes the integration between a unit for soft hydrocracking or Mild Hydrocracking (MHC) according to English terminology and a unit for hydrotreatment of diesel fuels, both in fixed beds. The integration is based on the recycling of the diesel fuel fraction obtained from MHC to the HDT unit so as to obtain a diesel fuel that complies with the Euro V specification. The hydrogen makeup of the complex is supplied by a common compressor and is advantageously sent in its entirety to the hydrotreatment unit so as to maximize the partial hydrogen pressure. The hydrogen makeup of the mild hydrocracking unit is produced from the separation section of the hydrotreatment unit. This operating mode requires that the units operate at compatible pressure levels. In this method, the entire hydrogen supply is sent into the hydrotreatment step, and the diesel fuel produced in the hydrocracking step is recycled in the step for hydrodesulfurization of the diesel fuels.

The patent U.S. Pat. No. 5,447,621 describes an integrated method for treatment of the middle distillate fraction, in which the diesel fuel fraction obtained from the 1-step fractionation of a hydrocracking device is recycled to a hydrotreatment step for the purpose of improving its properties. The preheating of this diesel fuel fraction is carried out by the heat recovered at the effluent from the hydrocracking step. The separation of the HDT effluent is carried out through the stripper side of the fractionation column of the hydrocracking device. The compression system of the makeup hydrogen is common to the two units and in the first place supplies the HDT step, and then the gaseous effluent from the hydrogen-rich hydrotreatment supplies the HCK step via additional compression stages.

The research work of the applicant led to discovering that a pooling of the makeup hydrogen compression system and an inter-unit thermal integration can be carried out and makes it possible to maximize the partial hydrogen pressure in the unit for hydrodesulfurization of diesel fuel with total iso-pressure, and primarily to limit the operating costs linked to utilities and to reduce the initial investment cost, while maintaining the quality of the products.

SUMMARY OF THE INVENTION

In particular, this invention relates to a complex for hydrotreatment and hydrocracking of petroleum fractions whose purpose is to maximize, in quality and quantity, the production of the middle distillate fraction.

The hydrocracking method treats hydrocarbon feedstocks containing at least 20% by volume and preferably at least 80% by volume of compounds boiling above 340° C., with said method comprising at least the following steps:

  • a) The hydrotreatment of said feedstocks in the presence of hydrogen and at least one hydrotreatment catalyst, at a temperature of between 200 and 450° C., under a pressure of between 2 and 18 MPa, at a volumetric flow rate of between 0.1 and 6 h-1, and with an amount of hydrogen introduced such that the volumetric ratio of liter of hydrogen/liter of hydrocarbon is between 100 and 2,000 L/L,
  • b) The hydrocracking of at least one part of the effluent obtained from step a), with the hydrocracking step b) being carried out, in the presence of hydrogen and at least one hydrocracking catalyst, at a temperature of between 250 and 480° C., under a pressure of between 2 and 25 MPa, at a volumetric flow rate of between 0.1 and 6 h−1, and with an amount of hydrogen introduced such that the volumetric ratio of liter of hydrogen/liter of hydrocarbon is between 100 and 2,000 L/L,
  • c) Passing into at least one heat exchanger of at least said effluent obtained from step b) in which said effluent is cooled by exchanging the liquid hydrocarbon feedstock entering into step f) in at least one exchanger,
  • d) The gas/liquid separation of the cooled effluent obtained from step c) to produce at least one hydrogen-rich gas efflux and at least one liquid efflux,
  • e) The fractionation of said liquid effluent obtained from step d) into at least one fraction comprising the converted hydrocarbon products having boiling points lower than 340° C. and an unconverted liquid fraction having a boiling point higher than 340° C.,
  • f) The hydrotreatment of a liquid hydrocarbon feedstock comprising at least 95% by weight of compounds boiling at a boiling point of between 150 and 400° C., preheated in advance in step c), with said step f) being carried out in the presence of hydrogen and at least one hydrotreatment catalyst, at a temperature of between 200 and 390° C., under a pressure of between 2 and 16 MPa, at a volumetric flow rate of between 0.2 and 5 h-1, and with an amount of hydrogen introduced such that the volumetric ratio of liter of hydrogen/liter of hydrocarbon is between 100 and 2,000 L/L,
  • g) The gas/liquid separation of the effluent obtained from step f) for producing at least one hydrogen-rich gas efflux and at least one liquid efflux,
  • h) The fractionation of the liquid effluent obtained from step g) making possible the separation of at least one light gas fraction, a naphtha fraction, and a middle distillate fraction having a boiling point higher than 150° C.,
  • i) The compression of the hydrogen-rich gas effluent obtained from step g) in a hydrogen makeup compressor supplying steps a), b) and f) and comprising n stages, with n being an integer that is greater than or equal to 2, with said hydrogen-rich gas effluent being injected and compressed in an intermediate stage of said compressor before being recycled upstream from step f).

One advantage of this invention is to provide a method integrating a hydrocracking method in one or two steps with a method for hydrodesulfurization of diesel fuels making it possible to maximize the partial hydrogen pressure in the diesel fuel hydrotreatment unit at total iso-pressure and to limit the weighted mean temperature of the catalyst in the step for hydrotreatment of diesel fuels thanks to the implementation of a compression step i) in a single compressor for hydrogen makeup in several stages, supplying steps a), b) and f) of the method according to the invention.

Another advantage of this invention is to provide a method that by integration of two methods makes it possible to reduce operating costs linked to utilities and to reduce the initial investment cost.

DETAILED DESCRIPTION OF THE INVENTION Feedstocks

This invention relates to a method for hydrocracking hydrocarbon feedstocks called source feedstocks, containing at least 20% by volume and preferably at least 80% by volume of compounds boiling above 340° C., preferably above 350° C., and in a preferred manner between 340 and 580° C. (i.e., corresponding to compounds containing at least 15 to 20 carbon atoms).

Said hydrocarbon feedstocks can advantageously be selected from among VGO (Vacuum Gas Oil) according to English terminology or vacuum distillates (DSV), such as, for example, the diesel fuels obtained from direct distillation of crude or conversion units, such as FCC, such as LCO or Light Cycle Oil according to English terminology, the coker or the visbreaking as well as feedstocks obtained from units for extraction of aromatic compounds from lubricating oil bases or obtained from dewaxing with solvent of lubricating oil bases, or else distillates coming from desulfurization or hydroconversion of RAT (atmospheric residues) and/or RSV (vacuum residues), or else the feedstock can advantageously be a deasphalted oil, or feedstocks obtained from biomass or else any mixture of the above-cited feedstocks and preferably VGO.

The paraffins obtained from the Fischer-Tropsch method are excluded.

In general, said feedstocks have a boiling point T5 higher than 340° C., and better yet higher than 370° C., i.e., 95% of the compounds present in the feedstock have a boiling point higher than 340° C., and better yet higher than 370° C.

The nitrogen content of the source feedstocks treated in the method according to the invention is usually higher than 500 ppm by weight, preferably between 500 and 10,000 ppm by weight, in a more preferred manner between 700 and 4,000 ppm by weight, and in an even more preferred manner between 1,000 and 4,000 ppm by weight. The sulfur content of the source feedstocks treated in the method according to the invention is usually between 0.01 and 5% by weight, in a preferred manner between 0.2 and 4% by weight, and in an even more preferred manner between 0.5 and 3% by weight.

The feedstock can optionally contain metals. The cumulative content of nickel and vanadium of the feedstocks that are treated in the method according to the invention is preferably less than 1 ppm by weight.

The asphaltene content is generally less than 3,000 ppm by weight, in a preferred manner less than 1,000 ppm by weight, in an even more preferred manner less than 200 ppm by weight.

The feedstock can optionally contain asphaltenes. The asphaltene content is generally less than 3,000 ppm by weight, in a preferred manner less than 1,000 ppm by weight, and in an even more preferred manner less than 200 ppm by weight.

In the case where the feedstock contains resin-type and/or asphaltene-type compounds, it is advantageous first to switch the feedstock to a catalyst bed or adsorbent bed that is different from the hydrocracking or hydrotreatment catalyst.

Step a)

In accordance with the invention, the method comprises a step a) for hydrotreatment of said feedstocks in the presence of hydrogen and at least one hydrotreatment catalyst, at a temperature of between 200 and 450° C., under a pressure of between 2 and 18 MPa, at a volumetric flow rate of between 0.1 and 6 h−1, and with an amount of hydrogen introduced such that the volumetric ratio of liter of hydrogen/liter of hydrocarbon is between 100 and 2,000 L/L.

The operating conditions such as temperature, pressure, hydrogen recycling rate, hourly volumetric flow rate, can be very variable based on the nature of the feedstock, the quality of the desired products, and installations used by the refiner.

Preferably, the hydrotreatment step a) according to the invention is carried out at a temperature of between 250 and 450° C., in a very preferred manner between 300 and 430° C., under a pressure of between 5 and 16 MPa, at a volumetric flow rate of between 0.2 and 5 h−1, and with an amount of hydrogen introduced such that the volumetric ratio of liter of hydrogen/liter of hydrocarbon is between 300 and 1,500 L/L.

Conventional hydrotreatment catalysts can advantageously be used, preferably that contain at least one amorphous substrate and at least one hydro-dehydrogenating element selected from among at least one element of non-noble groups VIB and VIII, and most often at least one element of group VIB and at least one element of the non-noble group VIII.

Preferably, the amorphous substrate is alumina or silica-alumina.

Preferred catalysts are selected from among the catalysts NiMo, NiW or CoMo on alumina and NiMo or NiW on silica-alumina.

An organic compound can be used during the preparation of the catalyst or else can be present in the porosity of the final catalyst.

The effluent obtained from the hydrotreatment step and entering into the hydrocracking step a) generally comprises a nitrogen content that is preferably less than 300 ppm by weight and preferably less than 50 ppm by weight.

In the hydrotreatment step, said feedstocks are advantageously desulfurized and denitrified before the latter is sent to the hydrocracking catalyst of step b) itself, in particular in the case where the latter comprises a zeolite.

This intensive hydrotreatment of the feedstock entrains only a limited conversion of the feedstock, into lighter fractions, which remains insufficient and is therefore to be completed in the more active hydrocracking catalyst.

Step b)

In accordance with the invention, the method comprises a step b) for hydrocracking at least one part of the effluent obtained from step a), and preferably in its entirety, with said step b) being carried out, in the presence of hydrogen and at least one hydrocracking catalyst, at a temperature of between 250 and 480° C., under a pressure of between 2 and 25 MPa, at a volumetric flow rate of between 0.1 and 6 h−1, and with an amount of hydrogen introduced such that the volumetric ratio of liter of hydrogen/liter of hydrocarbon is between 100 and 2,000 L/L.

Preferably, the hydrocracking step a) according to the invention is carried out at a temperature of between 320 and 450° C., in a very preferred manner between 330 and 435° C., under a pressure of between 3 and 20 MPa, at a volumetric flow rate of between 0.2 and 4 h−1, and with an amount of hydrogen that is introduced such that the volumetric ratio of liter of hydrogen/liter of hydrocarbon is between 200 and 2,000 L/L.

These operating conditions used in the method according to the invention generally make it possible to achieve conversions per pass of products having boiling points lower than 340° C., and, better, lower than 370° C., greater than 15% by weight, and in an even more preferred manner between 20 and 95% by weight.

The hydrocracking method according to the invention covers the fields of pressure and conversion ranging from mild hydrocracking to high-pressure hydrocracking. Mild hydrocracking is defined as hydrocracking leading to moderate conversions, generally less than 40%, and operating at low pressure, preferably between 2 MPa and 6 MPa. The high-pressure hydrocracking is generally carried out at higher pressures of between 5 MPa and 20 MPa, in such a way as to obtain conversions higher than 50%.

The hydrocracking method according to the invention can advantageously be carried out in one or two step(s), independently of the pressure at which said method is implemented. It is carried out in the presence of one or more hydrocracking catalyst(s), in one or more reaction unit(s) equipped with one or more reactor(s) in a fixed bed or in a boiling bed, optionally separated by one or more high-pressure and/or low-pressure separation sections.

According to a first embodiment according to the invention, the hydrocracking method according to the invention is implemented according to a so-called one-step mode. In this case, no separation step is implemented between the hydrotreatment step a) and the hydrocracking step b). The entire effluent exiting from the hydrotreatment step a) is injected into said hydrocracking step b) itself, and it is only then that separation of the products formed takes place in the fractionation step c) according to the invention.

According to a second embodiment of said one-step method, a step for incomplete separation of ammonia from the effluent obtained from the hydrotreatment step a) of said source hydrocarbon feedstocks is implemented. Preferably, said separation is advantageously carried out by means of an intermediate hot flash. The hydrocracking step b) according to the invention is then carried out in the presence of ammonia in an amount that is smaller than the amount that is present in said source hydrocarbon feedstocks, preferably less than 1,500 ppm by weight, in a more preferred manner less than 1,000 ppm by weight, and in an even more preferred manner less than 800 ppm by weight of nitrogen.

According to another embodiment according to the invention, the hydrocracking method according to the invention is implemented according to a so-called two-step mode. The second hydrocracking step will be described below.

The hydrotreatment step a) and the hydrocracking step b) can advantageously be carried out in the same reactor or in different reactors. In the case where they are produced in the same reactor, the reactor comprises multiple catalytic beds, with the first catalytic beds comprising the hydrotreatment catalyst(s) and the next catalytic beds comprising the hydrocracking catalyst(s).

Hydrocracking Catalyst of Step b)

The hydrocracking catalyst(s) used in the hydrocracking step b) are conventional hydrocracking catalysts of the bifunctional type combining an acid group with a hydrogenating group and optionally at least one bonding matrix.

Preferably, the hydrocracking catalyst(s) comprise(s) at least one metal of group VIII selected from among iron, cobalt, nickel, ruthenium, rhodium, palladium and platinum, and preferably cobalt and nickel and/or at least one metal of group VIB selected from among chromium, molybdenum, and tungsten, by itself or in a mixture, and preferably from among molybdenum and tungsten.

Hydrogenating groups of the NiMo, NiMoW, NiW type are preferred.

Preferably, the metal content of group VIII in the hydrocracking catalyst(s) is advantageously between 0.5 and 15% by weight and preferably between 2 and 10% by weight, with the percentages being expressed in terms of percentage by weight of oxides.

Preferably, the metal content of group VIB in the hydrocracking catalyst(s) is advantageously between 5 and 25% by weight and preferably between 15 and 22% by weight, with the percentages being expressed in terms of percentage by weight of oxides.

The catalyst(s) can also optionally comprise at least one promoter element deposited on the catalyst and selected from the group formed by phosphorus, boron, and silicon, optionally at least one element of group VIIA (fluorine, chlorine preferred), and optionally at least one element of group VIIB (manganese preferred), optionally at least one element of group VB (niobium preferred).

Preferably, the hydrocracking catalyst(s) comprise(s) a zeolite selected from among the USY zeolites, by itself or in combination, with other zeolites from among the following zeolites: beta, ZSM-12, IZM-2, ZSM-22, ZSM-23, SAPO-11, ZSM-48, ZBM-30, by themselves or in a mixture. In a preferred manner, the zeolite is the USY zeolite by itself.

The hydrocracking catalyst(s) can optionally comprise at least one porous or poorly-crystallized mineral matrix of the oxide type selected from among aluminas, silicas, silica-aluminas, aluminates, alumina-boron oxide, magnesia, silica-magnesia, zirconia, titanium oxide, clay, by themselves or in a mixture, and preferably alumina.

A preferred catalyst comprises and preferably consists of at least one metal of group VI and/or at least one metal of non-noble group VIII, a Y zeolite, and an alumina binder.

An even more preferred catalyst comprises and preferably consists of nickel, molybdenum, phosphorus, a Y zeolite, and alumina.

Another preferred catalyst comprises and preferably consists of nickel, tungsten, a Y zeolite and an alumina, or silica-alumina.

In a general way, the catalyst(s) used in the hydrocracking step b) advantageously contain(s):

  • 0.1 to 60% by weight of zeolite
  • 0.1 to 40% by weight of at least one element of groups VIB and VIII (% oxide)
  • 0.1 to 99.8% by weight of matrix (% oxide)
  • 0 to 20% by weight of at least one element selected from the group formed by P, B, Si (% oxide), preferably 0.1-20%
  • 0 to 20% by weight of at least one element of group VIIA, preferably 0.1 to 20%
  • 0 to 20% by weight of at least one element of group VIIB, preferably 0.1 to 20%
  • 0 to 60% by weight of at least one element of group VB, preferably 0.1 to 60%.

With the percentages being expressed in terms of percentage by weight in relation to the total catalyst mass, the sum of percentages of elements constituting said catalyst being equal to 100% of the total catalyst mass.

The hydrocracking catalyst(s) used according to the invention is (are) preferably subjected to a sulfurization treatment making it possible to transform, at least in part, the metal radicals into sulfide before they are brought into contact with the feedstock to be treated. This activation treatment by sulfurization is well known to one skilled in the art and can be carried out by any method already described in the literature.

Regardless of the embodiment of the hydrocracking method, the method according to the invention comprises a fractionation step c) comprising a fractionation unit placed downstream from the reactors, which makes it possible to separate the various products obtained from the hydrocracking reactor(s) of step b).

Step c)

In accordance with the invention, the method comprises a step c) for passing into at least one heat exchanger of at least said effluent obtained from step b), in which said effluent is cooled by exchanging the liquid hydrocarbon feedstock entering into step f) in at least one exchanger.

Said step c) is advantageously implemented in a number of heat exchangers of between 1 and 10, and preferably between 1 and 4, and in a very preferred manner 3.

In a preferred embodiment, at least one part of the effluent obtained from the hydrotreatment step a) in the case where steps a) and b) are implemented in different reactors, and/or at least one part and preferably the entirety of the effluent obtained from the second hydrocracking step j) in the case where the latter is implemented, can also be cooled by passing into at least one exchanger of said step c) by exchanging the liquid hydrocarbon feedstock entering into step f), preferably mixed with a stream of makeup and recycling hydrogen obtained from step i) and supplying step f), in at least one exchanger. In this case, the exchanges between the various streams may take place in the same exchanger or in different exchangers.

Step c) therefore makes possible the inter-unit thermal integration by making possible the preheating of at least the diesel-fuel-type liquid hydrocarbon feedstock of said hydrotreatment step f), by exchange with at least the effluent obtained from the hydrocracking step b) and/or obtained from the hydrotreatment step a), and/or obtained from the second hydrocracking step e).

According to this invention, the use of a furnace dedicated to the preheating of the diesel-fuel-type liquid hydrocarbon feedstock of said hydrotreatment step f) in normal operation is therefore no longer necessary. The result is a reduction in the investment and operating costs linked to the utilities (consumption of fuel gas) of the method.

Step d)

In accordance with the invention, the method comprises a step d) for gas/liquid separation of the cooled effluent obtained from step c) for producing at least one hydrogen-rich gas efflux and at least one liquid efflux. Preferably, step d) is carried out at high pressure.

After cooling in step c), the effluent obtained from the hydrocracking step b) is sent into a gas/liquid separation step d) at high pressure. Said separation step d) is advantageously carried out by means of a hot separator followed by a cold separator or by means of a single cold separator. A series of hot and cold separators at high and medium pressure can also be present.

The hot separator operates at high temperature, high pressure, with a temperature of between 50 and 450° C., preferably between 100 and 400° C., even more preferably between 200 and 300° C., and a pressure corresponding to the output pressure of b) minus the pressure drops. The cold separator operates at low temperature, high pressure, with a temperature of between 0 and 400° C., preferably between 0 and 400° C., even more preferably between 0 and 100° C., and a pressure corresponding to the output pressure of b) minus the pressure drops.

The hydrogen-rich gas efflux can advantageously be recycled in at least the hydrotreatment step a) and/or the hydrocracking step b) and/or in the second hydrocracking step j). Said gas effluent can advantageously be mixed with the makeup hydrogen obtained from step i) before its recycling in said step(s).

Step e)

In accordance with the invention, the method comprises a step e) for fractionation of said liquid effluent obtained from step d) into at least one fraction comprising the converted hydrocarbon products having boiling points lower than 380° C., preferably lower than 370° C., and in a preferred manner lower than 340° C., and an unconverted liquid fraction that has a boiling point higher than 340° C., preferably higher than 370° C., and in a preferred manner higher than 380° C., also called UCO or “unconverted oil” according to English terminology.

Preferably, said fractionation step d) comprises a first separation step comprising a separation means such as, for example, a separator tank or a steam stripper preferably operating at a pressure of between 0.5 and 2 MPa, which has as its object to carry out a separation of hydrogen sulfide (H2S) from at least one hydrocarbon effluent produced during steps a), b) and in an optional manner e). The hydrocarbon effluent, obtained from this first separation, can advantageously undergo atmospheric distillation, and in some cases the combination of atmospheric distillation and vacuum distillation. The distillation has as its object to carry out a separation between the converted hydrocarbon products, i.e., generally having boiling points lower than 380° C., preferably lower than 370° C., and in a preferred manner lower than 340° C., and an unconverted liquid fraction (UCO) (residue).

According to another variant, the fractionation step consists only of an atmospheric distillation column.

According to another variant, the separator (e) preferably consists of at least one distillation column, and in a very preferred manner a steam stripper followed by atmospheric distillation.

The converted hydrocarbon products having boiling points lower than 380° C., preferably lower than 370° C., and in a preferred manner lower than 340° C., are advantageously distilled at atmospheric pressure to obtain multiple converted fractions with a boiling point of at most 380° C., preferably at most 370° C., and in a preferred manner at most 340° C., and preferably a C1-C4 light gas fraction, at least one gasoline fraction, and at least one kerosene and diesel fuel middle-distillate fraction.

The unconverted liquid fraction having a boiling point higher than 340° C. (UCO) can advantageously be recycled entirely or partially, in the hydrotreatment step a) and/or in the hydrocracking step b) and/or in the second hydrocracking step e) in such a way as to adjust the rate of conversion or selectivity of the method according to the invention.

Optional Step j)

In another embodiment of the method according to the invention, said method is implemented according to a so-called two-step hydrocracking method. In this case, at least one part and preferably all of the liquid fraction having a boiling point higher than 340° C. (UCO), which is unconverted during the first hydrocracking step b) and obtained from the fractionation step e), is sent into a second hydrocracking step j).

Preferably, said second hydrocracking step j) is implemented under conditions that are identical to or different from those of said hydrocracking step b) and in the presence of a hydrocracking catalyst that is identical to or different from the one implemented in said step b).

Preferably, said second hydrocracking step j) is implemented, in the presence of hydrogen and at least one hydrocracking catalyst, at a temperature of between 250 and 480° C., preferably between 320 and 450° C., and in a very preferred manner between 330 and 435° C., under a pressure of between 2 and 25 MPa, preferably between 3 and 20 MPa, at a volumetric flow rate of between 0.1 and 6 h-1, and preferably between 0.2 and 3 h-1, and with an amount of hydrogen introduced such that the volumetric ratio of liter of hydrogen/liter of hydrocarbon is between 100 and 2,000 L/L, and preferably between 200 and 2,000 L/L.

The description of the catalyst used in said second hydrocracking step j) is identical to the one of the catalyst used in said first step b).

Preferably, the catalyst used in step j) is different from the one of step b). The effluent produced in the second hydrocracking step j) can advantageously, in its entirety or partially, be sent into the gas/liquid separation step d) and/or into step c) of the method according to the invention.

Step f)

In accordance with the invention, the method comprises a step f) for hydrotreatment of a liquid hydrocarbon feedstock comprising at least 95% by weight of compounds boiling at a boiling point of between 150 and 400° C., preferably between 150 and 380° C., and in a preferred manner between 200 and 380° C., preferably preheated in step c), with said step f) being carried out in the presence of hydrogen and at least one hydrotreatment catalyst, at a temperature of between 200 and 390° C., under a pressure of between 2 and 16 MPa, at a volumetric flow rate of between 0.2 and 5 h-1, and with an amount of hydrogen introduced such that the volumetric ratio of liter of hydrogen/liter of hydrocarbon is between 100 and 2,000 L/L.

Preferably, said liquid hydrocarbon feedstock treated in step f) is advantageously selected from among the liquid hydrocarbon feedstocks obtained from the direct distillation of a crude oil (or straight run according to English terminology) and preferably selected from among the straight-run diesel fuel, the Light Vacuum Gasoil Oil (LVGO) according to English terminology, or the light vacuum distillate, and the liquid hydrocarbon feedstocks obtained from a coking unit (coking according to English terminology), preferably coker diesel fuel, from a visbreaking unit (visbreaking according to English terminology), a steam-cracking unit (steam cracking according to English terminology) and/or from a catalytic cracking unit (Fluid Catalytic Cracking according to English terminology), preferably the LCO (light cycle oil) or light diesel fuels obtained from a catalytic cracking unit, and a diesel fuel feedstock obtained from biomass conversion (esterification, for example); said feedstocks can be taken by themselves or in a mixture.

According to the invention, the diesel-fuel-type liquid hydrocarbon feedstock treated in step f) is advantageously preheated, preferably in a mixture with a stream of makeup and recycling hydrogen obtained from step i), by passing into step c) according to the invention. Said feedstock is advantageously preheated at the temperature that makes it possible to reach the WABT or weighted mean temperature in the catalyst beds of the hydrotreatment reactor of step f).

According to a preferred embodiment, said feedstock is preheated by passing into at least one exchanger of step c) by heat exchange with at least the effluent obtained from the hydrocracking step b) and/or obtained from the hydrotreatment step a) in the case where steps a) and b) are implemented in different reactors, and/or obtained from the second hydrocracking step j) in the case where the latter is implemented.

In a very preferred embodiment, a first heat exchange is carried out for all or part of the effluent obtained from the hydrotreatment step a), a second exchange can be carried out for at least one part and preferably all of the effluent obtained from the hydrocracking step b), and a last exchange can be carried out for all or part of the effluent obtained from the second hydrocracking step j).

Preferably, the hydrotreatment step f) according to the invention is carried out at a temperature of between 230 and 350° C., in a very preferred manner between 250 and 350° C., under a pressure of between 5 and 16 MPa, at a volumetric flow rate of between 0.2 and 4 h−1, and with an amount of hydrogen introduced such that the volumetric ratio of liter of hydrogen/liter of hydrocarbon is between 300 and 1,500 L/L.

The description of the hydrotreatment catalysts used in step f) is identical to those used in step a). They can be identical to or different from those used in step a).

Step g)

In accordance with the invention, the method comprises a step g) for gas/liquid separation of the effluent obtained from step f) for producing at least one hydrogen-rich gas efflux and at least one liquid efflux.

Preferably, step g) is carried out at high pressure.

Said separation step g) is advantageously carried out by means of a hot separator followed by a cold separator or by means of a single cold separator. A series of hot and cold separators at high and medium pressure can also be present.

The hot separator operates at high temperature, high pressure, with a temperature of between 50 and 450° C., preferably between 100 and 400° C., even more preferably between 200 and 300° C., and a pressure corresponding to the output pressure of f) minus the pressure drops. The cold separator operates at low temperature, high pressure, with a temperature of between 0 and 400° C., preferably between 0 and 400° C., even more preferably between 0 and 100° C., and a pressure corresponding to the output pressure of f) minus the pressure drops.

According to the invention, the hydrogen-rich gas efflux obtained from step g) is sent into a compression step i).

According to the invention, the liquid effluent obtained from step g) is sent into a fractionation step h).

Step h)

In accordance with the invention, the method comprises a step h) for fractionation of the liquid effluent obtained from step g) making it possible to separate at least one light gas fraction, a naphtha fraction, and a middle distillate fraction having a boiling point higher than 150° C.

Preferably, said fractionation step h) comprises a separation step comprising a separation means, such as, for example, a separator tank or a steam stripper operating preferably at a pressure of between 0.5 and 2 MPa, which has as its object to carry out a separation of hydrogen sulfide (H2S) from at least one hydrocarbon effluent produced in the hydrotreatment step f). Preferably, said step h) produces a stream of light gases (C1-C4), a naphtha stream with a boiling point lower than 150° C., and a middle distillate stream with a boiling point higher than 150° C. and preferably boiling between 150 and 370° C.

Step i)

In accordance with the invention, the method comprises a step i) for compression of the hydrogen-rich gas effluent obtained from step g) in a hydrogen makeup compressor supplying steps a), b) and f), and optionally j), and comprising n stages, with n being an integer that is greater than or equal to 2, said hydrogen-rich gas effluent being injected and compressed in an intermediate stage of said compressor before being recycled upstream from the hydrotreatment step f), preferably upstream from step c).

Preferably, the compressor comprises a number of stages n of between 2 and 5, preferably between 2 and 4, and in a particularly preferred way equal to 3.

The steps for hydrotreatment of diesel fuel f) and the steps for hydrocracking vacuum distillate implemented in steps a), b) and optionally j) of this invention are conducted at distinct pressures. The implementation of said compression step i) in a single hydrogen makeup compressor in several stages, supplying steps a), b) and optionally j) and step f), makes it possible to use different pressures for each of said steps a), b) and optionally j) and step f).

Thus, the hydrotreatment step a) and the hydrocracking step b) and optionally j) are advantageously supplied by hydrogen coming from the outlet of the last compression stage of said step i), and the hydrotreatment step f) is advantageously supplied by the outlet from an intermediate compression stage of said step i), i.e., at a lower pressure.

In the particular embodiment where n is equal to 3, the hydrogen obtained from the outlet of the second compression stage supplies the hydrotreatment step of f) and is mixed with the diesel-fuel-type liquid hydrocarbon feedstock entering into said step f).

According to a particular embodiment, the partial hydrogen pressure in the hydrotreatment reactor of step f), PH2, is between 3.0 and 8.0 MPa.

These optimized partial hydrogen pressure values are made possible by the mode of operation of the compression step i) of this invention. The gas effluent comprising the recycling hydrogen produced in the hydrotreatment step f) and separated in step g) is not picked up here by a dedicated compressor but by the common compression system implemented in step i).

According to the invention, said hydrogen-rich gas effluent obtained from step g) is injected and compressed in an intermediate stage of said compressor before being recycled upstream from the hydrotreatment step f). In the preferred mode where n is equal to 3, said gas effluent is injected between the first and second compression stages and compressed in the second compression step.

Said hydrogen-rich gas effluent obtained from step g) is advantageously mixed with the makeup hydrogen of the method according to the invention at the intake of an intermediate compression stage, and preferably between the first and second compression steps in the case where n is equal to 3, which has the effect of diluting it and increasing its hydrogen purity.

Said hydrogen-rich gas effluent obtained from step g) is then compressed by this intermediate stage and preferably the second stage, before being recycled upstream from the hydrotreatment step f).

The hydrogen stream supplying the hydrotreatment step f) from the outlet of the intermediate stage, and preferably from the second step in the case where n is equal to 3, therefore consists of a mixture of makeup hydrogen and recycling gas coming from the hydrotreatment step f) and separated in step g).

This mode of operation makes it possible to dilute the recycling gas with the makeup hydrogen of the method with high purity, therefore an increase of the partial hydrogen pressure of the hydrotreatment step f). It primarily makes possible a reduction in the overall investment thanks to the elimination of the dedicated recycling compressor.

DESCRIPTION OF THE FIGURES

FIG. 1 illustrates the invention and its preferred embodiments.

The vacuum distillate feedstock (1), optionally in a mixture with the unconverted fraction (34) obtained from the fractionation step e), is sent into a first hydrotreatment step a) with a hydrogen makeup stream (2), completed by the recycled hydrogen (3) obtained from a gas/liquid separation step d). The effluent of the first hydrotreatment step a) supplies the first hydrocracking step b) via the line (4) or via the line (5) that once cooled by passing into an exchanger of step c) is sent back to the hydrocracking step b) via the line (6). Optionally, a part of the unconverted fraction is recycled in step b) via the pipe (35). The monitoring of the weighted mean temperature (WABT) of the hydrocracking reactor can thus be carried out in two ways: either by a quenching of recycled hydrogen-rich gas effluent (31) mixed with the line (4), or by an energy recovery step c) that makes it possible to preheat the diesel-fuel-type feedstock of the hydrotreatment step f).

The effluent (7) of the first hydrocracking step b) is first cooled in step c) by passing into an exchanger, which makes possible the transfer of calories to the diesel fuel feedstock entering into the hydrotreatment step (f) via the pipe (18) in a mixture with the recycling and makeup hydrogen via the pipe (19). The cooled effluent (8) exiting from the exchanger is sent to a separation step d). The latter makes it possible to obtain at least one hydrogen-rich gas efflux (3) and a liquid efflux (9) that contains for the most part converted fractions and a smaller proportion of unconverted fractions. The liquid stream (9) is then sent into a fractionation step e) that makes it possible to obtain a middle-distillate-type fraction (12) and a heavier fraction than the diesel fuel (13), an acid gas stream containing H2S (10), and a naphtha-type fraction (11).

The unconverted fraction obtained from the fractionation step e) can optionally constitute the vacuum distillate feedstock (14) sent to the second hydrocracking step (j). The feedstock (14) is optionally mixed with a recycled hydrogen-rich gas effluent (32) and obtained from the separation step (d) and with a makeup hydrogen effluent (33). After cooling by passing into an exchanger of step c) via the line (16), the effluent of the second hydrocracking step j) can optionally be sent to the separation step (d) at high pressure via the line (15). The calories available at the outlet of step (j) can therefore be used in step (c) for passing by an exchanger making possible thermal integration between units so as to preheat the feedstock of the hydrotreatment step (f). The cooled effluent (17) is directed toward the separation step (d) in a mixture with the effluent of the first hydrocracking step (8).

The diesel fuel feedstock (18) is sent with a stream of recycling and makeup hydrogen (19) into a preheating step at high temperature by passing into an exchanger (c) making it possible to reach the WABT required in the hydrotreatment step (f). This step (c) takes place within heat exchangers operating with, on the one hand, the feedstock (18) of the HDT and, on the other hand, the effluents (7) and/or (5) produced in steps (a) and (b), and in an optional manner the effluent (16) of step (e). The preheated feedstock (20) is treated in the hydrotreatment reactor of step (f). Its effluent (21) is, after cooling, sent to the separation step (g) at high pressure. The latter makes it possible to obtain at least one hydrogen-rich gas effluent (22) and at least one liquid effluent (23). The liquid effluent (23) is then sent to a fractionation step h) making it possible to obtain at least one middle distillate fraction (26) and a stream of acid gas containing H2S (24). A naphtha fraction (25) can also be separated. The fractionation step (h) is carried out in a preferred manner within a steam stripping column.

The single compression system of step (i), and common to two hydrocracking and hydrotreatment units, is supplied by the gas stream (27) containing all of the makeup hydrogen necessary to the method. According to a preferred variant shown in the figure, the compression is carried out via 3 stages. The hydrogen stream (29) recovered at the outlet from the 1st compression stage is mixed with the recycling gas (22) of the diesel fuel HDT unit produced in step (g). The mixture (28) is sent to the intake of the 2nd compression stage. The pressure level obtained at the outlet from the 2nd stage is compatible with the pressure level required in the hydrotreatment step (f). The gas stream (19) thus supplies the diesel fuel hydrotreatment unit with the necessary makeup and recycling hydrogen. The hydrogen contained in the stream (30) is compressed in a3rd stage. At the outlet, the pressure level obtained makes it possible to supply steps a) and b) with the makeup hydrogen that is necessary (2) to the hydrotreatment and hydrocracking reactions of vacuum distillates. A stream of makeup hydrogen (33) is sent to the 2nd hydrocracking step j).

Without further elaboration, it is believed that one skilled in the art can, using the preceding description, utilize the present invention to its fullest extent. The preceding preferred specific embodiments are, therefore, to be construed as merely illustrative, and not limitative of the remainder of the disclosure in any way whatsoever.

In the foregoing and in the examples, all temperatures are set forth uncorrected in degrees Celsius and, all parts and percentages are by weight, unless otherwise indicated.

The entire disclosures of all applications, patents and publications, cited herein and of corresponding application No. FR 1759088, filed Sep. 29, 2017 are incorporated by reference herein.

The examples illustrate the invention without limiting its scope.

EXAMPLES Example 1 Not in Accordance With the Invention

The complex for production of middle distillates consists of two units: one unit for hydrotreatment of diesel fuel and one unit for hydrocracking of vacuum distillates in two steps.

According to Example 1, the two units follow a standard scheme and are operated independently from one another. Only the hydrogen makeup compressor is common to the two units.

Feedstocks

The hydrotreatment unit treats a diesel fuel feedstock described in Table 1:

TABLE 1 Properties of the Diesel Fuel Feedstock Properties Unit Diesel Fuel Mixture Flow Rate t/h 319.9 d15 4 t/m3 0.8628 PI TBP ° C. 143 PF TBP ° C. 383 S % by weight 0.82 N wtppm 632

The hydrotreatment unit treats a vacuum distillate feedstock (DSV) described in Table 2:

TABLE 2 Properties of the DSV Feedstock Properties Unit DSV Mixture Flow Rate t/h 478.7 d15 4 t/m3 0.955 PI TBP ° C. 350 PF TBP ° C. 760 S % by weight 2.08 N wtppm 2,142

Hydrotreatment of Diesel Fuels

The diesel fuel feedstock described in Table 1 is injected into a preheating step comprising a furnace dedicated to the hydrotreatment unit and then sent to the hydrotreatment reactor under the following conditions:

TABLE 3 Operating Conditions of the Reactor - Diesel Fuel HDT Unit Unit Operating Conditions WABT SOR ° C. 340 Catalyst — HR 1248 H2/HC Nm3/Sm3 800 Partial H2 Pressure MPa 78.0 VVH h−1 0.95

The catalyst used is a NiMo alumina catalyst marketed by the Axens Company. The effluent is sent into a separation step consisting of a heat recovery train and then separation at high pressure including a recycling compressor dedicated to the diesel fuel HDT unit. This section makes it possible to separate, on the one hand, hydrogen, hydrogen sulfide and ammonia, and, on the other hand, the effluent supplying a stripper. The stripping step makes it possible to fractionate the effluent into a gas stream containing H2S and light ends, a naphtha stream, and a stream of middle distillates at the desired specification.

Two-Step DSV Hydrocracking Device

The DSV feedstock is injected into a preheating step and then into a hydrotreatment reactor under the following conditions:

TABLE 4 Operating Conditions of the Reactor 1 - DSV HCK Unit Unit Operating Conditions WABT SOR ° C. 384 Catalyst — HRK 1448 H2/HC Nm3/Sm3 1,200 Partial H2 Pressure MPa >14.5 VVH h−1 0.60

The catalyst used is a NiMo alumina catalyst marketed by the Axens Company.

The effluent from this reactor is then mixed with a hydrogen stream to be cooled and then injected into a second so-called hydrocracking reactor R2 operating under the conditions of Table 5:

TABLE 5 Operating Conditions of Reactor 2 - DSV HCK Unit Unit Operating Conditions WABT SOR ° C. 393 Catalyst — HYK 743 H2/HC Nm3/Sm3 1,200 Partial H2 Pressure MPa >14.5 VVH h−1 2.70

The catalyst used is a metal zeolite catalyst marketed by the Axens Company. R1 and R2 constitute the first step of the hydrocracking device; the effluent of R2 is then sent into a separation step that consists of a train of heat recovery and then separation at high pressure including a recycling compressor and making it possible to separate, on the one hand, hydrogen, hydrogen sulfide, and ammonia, and, on the other hand, the effluent that supplies a stripper and then an atmospheric fractionation column so as to separate the streams concentrated in H2S, naphtha, kerosene, diesel fuel at the desired specification, and an unconverted heavy stream. This unconverted heavy stream is injected into a preheating step and then into a hydrocracking reactor R3 constituting the second hydrocracking step. This reactor R3 is implemented under conditions set forth in Table 6:

TABLE 6 Operating Conditions of Reactor 3 - DSV HCK Unit Unit Operating Conditions WABT SOR ° C. 370 Catalyst — HDK 766 H2/HC Nm3/Sm3 1,000 Partial H2 Pressure MPa >12.5 VVH h−1 1.50

The catalyst used is a metal catalyst on amorphous silica-alumina marketed by the Axens Company.

The effluent of R3 is then injected into a separation step at high pressure, and the hydrogen-rich gas stream is recycled.

The middle distillate fraction produced in the hydrocracking device and recovered in the fractionation column complies with the Euro V specifications; in particular, it has less than 10 ppm by weight of sulfur.

Investment Costs Hydrotreatment of Diesel Fuel

An estimation of the cost of the diesel fuel HDT unit (reference year 2015 and Europe zone) and the distribution of this investment by type of equipment is provided in Table 7.

TABLE 7 Estimation of the Investment - Diesel Fuel HDT Unit Number Setup Costs Type of Equipment of Items (thousands of USD) Furnaces 1 4,054 Reactors 1 12,143 Columns 2 3,067 Tanks 8 3,782 Heat Exchangers 18 9,977 Cooling Towers 3 5,033 Pumps and Driving Machines 10 8,416 Compressors and Driving Machines 1 8,497 Storage Units 0 0 Miscellaneous 5 1,534 Method's Margin of Error 0 5,650 Total Unit Cost 49 62,153

Two-Step DSV Hydrocracking Device

An estimation of the cost of the DSV HCK unit (reference year 2015 and Europe zone) and the distribution of this investment by type of equipment is provided in Table 8.

TABLE 8 Estimation of the Investment - DSV HCK Unit Number Setup Costs Type of Equipment of Items (thousands of USD) Furnaces 3 14,531 Reactors 5 65,518 Columns 13 20,735 Tanks 27 24,915 Heat Exchangers 47 37,442 Cooling Towers 23 22,454 Pumps and Driving Machines 56 31,637 Compressors and Driving Machines 13 66,849 Storage Units 0 0 Miscellaneous 2 1,108 Method's Margin of Error 0 28,519 Total Unit Cost 189 313,707

Example 2 In Accordance With the Invention

In the example in accordance with the invention, the integration of units is more advanced. A common compression system is installed: the recycling gas of the diesel fuel HDT unit is compressed by the 2nd stage of the hydrogen makeup compressor. The feedstock preheating furnace dedicated to the diesel fuel HDT unit is replaced by exchanger calendars recovering the energy available to the inter-reactor of the DSV HCK unit.

Feedstocks

The method according to Example 2 is carried out with the same feedstocks as in Example 1.

Primary Operating Conditions Hydrotreatment of Diesel Fuel

The method according to Example 2 is carried out according to the same operating conditions as in Example 1.

The pooling of the compression system makes possible, however, an improvement in the partial hydrogen pressure of the diesel fuel HDT unit: the latter, by a dilution effect of the recycling gas with the H2 makeup of the complex, observes a rise of +2 points (8 MPa), which is beneficial for the service life of the catalyst.

Two-Step DSV Hydrocracking Device

The method according to Example 2 is carried out according to the same operating conditions as in Example 1.

Investment Costs Hydrotreatment of Diesel Fuel

An estimation of the cost of the diesel fuel HDT unit (reference year 2015 and Europe zone) according to the invention and the distribution of this investment by type of equipment is provided in Table 9.

TABLE 9 Estimation of the Investment According to the Invention - Diesel Fuel HDT Unit Number Setup Costs Type of Equipment of Items (thousands of USD) Furnaces 0 0 Reactors 1 12,143 Columns 2 3,067 Tanks 8 3,782 Heat Exchangers 20 12,384 Cooling Towers 3 5,033 Pumps and Driving Machines 10 8,416 Compressors and Driving Machines 0 0 Storage Units 0 0 Miscellaneous 5 1,534 Method's Margin of Error 0 4,636 Total Unit Cost 49 50,995

The invention makes it possible to eliminate the furnace and the recycling compressor, which constitute significant cost items in a diesel fuel HDT unit. The increase in investment cost amounts to $11.2 million, or a relative reduction of 18%.

The visible increase in the exchangers item (+$2.4 million) reflects the replacement of the furnace by a heat exchanger for the HCK effluent. The additional cost is less than the price of the furnace in question.

Two-Step DSV Hydrocracking Device

An estimation of the cost of the DSV HCK unit (reference year 2015 and Europe zone) according to the invention and the distribution of this investment by type of equipment is provided in Table 10.

TABLE 10 Estimation of the Investment According to the Invention - DSV HCK Unit Number Setup Costs Type of Equipment of Items (thousands of USD) Furnaces 3 14,531 Reactors 5 65,518 Columns 13 20,735 Tanks 27 24,915 Heat Exchangers 46 37,050 Cooling Towers 23 22,454 Pumps and Driving Machines 56 31,637 Compressors and Driving Machines 13 72,361 Storage Units 0 0 Miscellaneous 2 1,108 Method's Margin of Error 0 29,031 Total Unit Cost 188 319,339

The reduction in investment cost noted on the HDT side of diesel fuels is reflected on the HCK side as increases in the compressor items and the HCK investment (+$5.6 M). The relative increase is very small since it is less than 2%.

The 2nd stage is resized to be able to recycle the hydrogen-rich gas of the diesel fuel HDT unit. The additional cost (+$5.5 M) remains well below that of the cost of the recycling compressor.

Overall, the invention therefore makes possible an improvement in the investment in the complex.

To this improvement in investment cost, we should add increases in operating costs linked to utilities. The consumption in fuel gas of the furnace dedicated to diesel fuel HDT is canceled according to the invention. The same holds true for the consumption of high-pressure steam, making possible the driving of the recycling compressor dedicated to said unit. An estimation of the annual reductions on these two items for a Europe zone and a reference year 2015 is proposed in Table 11.

TABLE 11 Reduction in Outlays Linked to Utilities, According to the Invention Hourly Reduction in Utility Price Consumption Annual Outlays Fuel Gas 33.73 Gcal/h  9.9 Gcal/h $2.80 M/year High-Pressure Steam $41.30/ton 21.2 ton/h $7.38 M/year

The preceding examples can be repeated with similar success by substituting the generically or specifically described reactants and/or operating conditions of this invention for those used in the preceding examples.

From the foregoing description, one skilled in the art can easily ascertain the essential characteristics of this invention and, without departing from the spirit and scope thereof, can make various changes and modifications of the invention to adapt it to various usages and conditions.

Claims

1. A hydrocracking method for treating hydrocarbon feedstocks containing at least 20% by volume and preferably at least 80% by volume of compounds boiling above 340° C., said method comprising:

a) hydrotreatment of said feedstocks in the presence of hydrogen and at least one hydrotreatment catalyst, at a temperature of between 200 and 450° C., under a pressure of between 2 and 18 MPa, at a volumetric flow rate of between 0.1 and 6 h−1, and with an amount of hydrogen introduced such that the volumetric ratio of liter of hydrogen/liter of hydrocarbon is between 100 and 2,000 L/L,
b) hydrocracking of at least one part of the effluent obtained from step a), with the hydrocracking step b) being carried out, in the presence of hydrogen and at least one hydrocracking catalyst, at a temperature of between 250 and 480° C., under a pressure of between 2 and 25 MPa, at a volumetric flow rate of between 0.1 and 6 h−1, and with an amount of hydrogen introduced such that the volumetric ratio of liter of hydrogen/liter of hydrocarbon is between 100 and 2,000 L/L,
c) passing into at least one heat exchanger of at least said effluent obtained from step b) in which said effluent is cooled by exchanging the liquid hydrocarbon feedstock entering into step f) in at least one exchanger,
d) gas/liquid separation of the cooled effluent obtained from step c) to produce at least one hydrogen-rich gas efflux and at least one liquid efflux,
e) fractionation of said liquid effluent obtained from step d) into at least one fraction comprising the converted hydrocarbon products having boiling points lower than 340° C. and an unconverted liquid fraction having a boiling point higher than 340° C.,
f) hydrotreatment of a liquid hydrocarbon feedstock comprising at least 95% by weight of compounds boiling at a boiling point of between 150 and 400° C., preheated in advance in step c), with said step f) being carried out in the presence of hydrogen and at least one hydrotreatment catalyst, at a temperature of between 200 and 390° C., under a pressure of between 2 and 16 MPa, at a volumetric flow rate of between 0.2 and 5 h−1, and with an amount of hydrogen introduced such that the volumetric ratio of liter of hydrogen/liter of hydrocarbon is between 100 and 2,000 L/L,
g) gas/liquid separation of the effluent obtained from step f) for producing at least one hydrogen-rich gas efflux and at least one liquid efflux,
h) fractionation of the liquid effluent obtained from step g) making possible the separation of at least one light gas fraction, a naphtha fraction, and a middle distillate fraction having a boiling point higher than 150° C.,
i) compression of the hydrogen-rich gas effluent obtained from step g) in a hydrogen makeup compressor supplying steps a), b) and f) and comprising n stages, with n being an integer that is greater than or equal to 2, with said hydrogen-rich gas effluent being injected and compressed in an intermediate stage of said compressor before being recycled upstream from step f),
j) hydrocracking of at least one part of the liquid fraction having a boiling point higher than 340° C. that is unconverted during the first hydrocracking step b) and obtained from the fractionation step e), with said second hydrocracking step j) being carried out in the presence of hydrogen and at least one hydrocracking catalyst, at a temperature of between 250 and 480° C., under a pressure of between 2 and 25 MPa, at a volumetric flow rate of between 0.1 and 6 h-1, and with an amount of hydrogen introduced such that the volumetric ratio of liter of hydrogen/liter of hydrocarbon is between 100 and 2,000 L/L.

2. Method according to claim 1, in which the hydrocarbon feedstocks treated in said method and sent into step a) are selected from among the hydrocarbon feedstocks containing at least 80% by volume of compounds boiling between 340-580° C.

3. Method according to claim 1, in which the hydrocarbon feedstocks treated in said method and sent into step a) are selected from among the vacuum distillates (DSV) selected from among the diesel fuels obtained from direct distillation of crude or conversion units and the distillates coming from the desulfurization or hydroconversion of atmospheric residues and/or vacuum residues, deasphalted oils, and the feedstocks obtained from biomass or else any mixture of the feedstocks cited above.

4. Method according to claim 1, in which the hydrocracking catalyst(s) used in step b) comprise(s) at least one metal of group VIII selected from among iron, cobalt, nickel, ruthenium, rhodium, palladium and platinum, and/or at least one metal of group VIB selected from among chromium, molybdenum, and tungsten, by itself or in a mixture, and a zeolite selected from among the USY zeolites, by itself or in combination, with other zeolites from among the following zeolites: beta, ZSM-12, IZM-2, ZSM-22, ZSM-23, SAPO-11, ZSM-48, ZBM-30, by themselves or in a mixture.

5. Method according to claim 1, in which at least one part of the effluent obtained from the hydrotreatment step a) and/or at least one part of the effluent obtained from the second hydrocracking step j) is/are cooled by passing into at least one exchanger of said step c) by exchanging the liquid hydrocarbon feedstock entering into step f), mixed with a stream of makeup and recycling hydrogen obtained from step i) and supplying step f), in the same exchanger or in different exchangers.

6. Method according to claim 1, in which said step c) is implemented in a number of heat exchangers of between 1 and 10.

7. Method according to claim 1, in which said liquid hydrocarbon feedstock treated in the hydrotreatment step f) is selected from among the diesel fuel obtained from atmospheric fractionation of crude oil, the Light Vacuum Gasoil Oil (LVGO) according to English terminology or light vacuum distillate, and the liquid hydrocarbon feedstocks obtained from a coking unit (coking according to English terminology), preferably coker diesel fuel, from a visbreaking unit (visbreaking according to English terminology), a steam-cracking unit (steam cracking according to English terminology) and/or from a catalytic cracking unit (Fluid Catalytic Cracking according to English terminology), preferably the LCO (light cycle oil) or light diesel fuels obtained from a catalytic cracking unit, and a diesel fuel feedstock obtained from biomass conversion.

8. Method according to claim 1, in which the hydrotreatment step f) according to the invention is carried out at a temperature of between 230 and 350° C., in a very preferred manner between 250 and 350° C., under a pressure of between 5 and 16 MPa, at a volumetric flow rate of between 0.2 and 4 h−1, and with an amount of hydrogen introduced such that the volumetric ratio of liter of hydrogen/liter of hydrocarbon is between 300 and 1,500 L/L.

9. Method according to claim 1, in which the compressor of step i) comprises a number of stages n of between 2 and 4.

10. Method according to claim 9, in which said compressor comprises 3 stages.

11. Method according to claim 1, in which the hydrotreatment step a) and the hydrocracking step b) are supplied by hydrogen coming from the outlet of the last compression stage of said step i), and the hydrotreatment step f) is supplied by the outlet of an intermediate compression stage of said step i).

12. Method according to claim 10, where n is equal to 3, wherein the hydrogen coming from the outlet of the second compression stage which supplies the hydrotreatment step f is mixed with the liquid hydrocarbon feedstock entering into said step f).

13. Method according to claim 10, in which said hydrogen-rich gas effluent obtained from step g) is injected between the first and second compression stages and compressed in the second compression stage.

14. Method according to claim 10, in which said hydrogen-rich gas effluent obtained from step g) is mixed with the makeup hydrogen at the intake between the first and second compression stages and then compressed by the second stage, before being recycled upstream from the hydrotreatment step f).

Patent History
Publication number: 20190100706
Type: Application
Filed: Sep 28, 2018
Publication Date: Apr 4, 2019
Applicant: IFP Energies Nouvelles (Rueil-Malmaison Cedex)
Inventors: Elodie TELLIER (Lyon), Jerome BONNARDOT (Le Chesnay)
Application Number: 16/145,397
Classifications
International Classification: C10G 69/04 (20060101); C10L 1/08 (20060101);