Gas-solid co-current downflow fluidised bed catalytic cracking process with oriented feed injector

Abstract

The invention relates to a gas-solid co-current downflow fluidised bed catalytic cracking process using: a vertical pipeline (1) carrying a downflow (4) of catalyst particles; a mixing chamber (2) comprising at least one first injector (5) of hydrocarbon feed (6); a gas-solid co-current downflow fluidised bed reactor (3) supplied with a catalyst and a hydrocarbon feed, the first injector having a predetermined angle α with respect to the horizontal so that: the vector of the resulting momentum (Mtot), calculated from the vector sum of the feed momentum (M6) and the catalyst momentum (M4), has an angle λ with respect to a horizontal plane of 70°-80°; and the ratio of the vertical component of the feed momentum (M6v) and the vertical and downflow momentum of the catalyst is between -0.2 and 0.1.

Description

[0001] FALLING GAS-SOLID CO-CURRENT FLUIDIZED BED CATALYTIC CRACKING PROCESS WITH ORIENTED CHARGE INJECTOR

[0002] Technical field

[0003] The invention relates to the field of refining and petrochemistry and to processes and units for the chemical transformation of petroleum products, in particular hydrocarbon cuts, by Fluid Catalytic Cracking (FCC) for the production of light olefins (i.e., olefins comprising between 2 and 4 carbon atoms), and more particularly ethylene and propylene, and also aromatics (e.g. BTX), and more particularly paraxylene.

[0004] Prior art

[0005] The invention is part of the improvement of the design of the established flow zone of downward gas-solid co-current fluidized bed reactors ("downer" or "down flow reactor" according to English terminology), hereinafter called downward flow reactors, used for example for high severity catalytic cracking (HS-FCC).

[0006] Ethylene, Propylene, Butene, Butadiene and aromatics such as Benzene, Toluene and Xylene (BTX) represent the basic products for the petrochemical industry. These products are generally obtained by catalytic reforming and / or thermal cracking (steam cracking) of hydrocarbons such as naphtha, kerosene or diesel. These compounds are also obtained by fluidized catalytic cracking (FCC) of hydrocarbons, such as a Vacuum Gas Oil (VGO) and / or a residue (under vacuum or atmospheric) from the distillation of hydrocarbons and / or naphtha, diesel, and complete crudes.

[0007] The high severity catalytic cracking (HS-FCC) process aims to increase propylene and ethylene yields through high temperature reaction conditions, very short contact times (eg ~1 s), high ratios between the mass flow rate C of catalyst and the mass flow rate O of feedstock (C / O).

[0008] The disadvantages associated with a conventional FCC reactor with a rising gas-solid co-current fluidized bed (riser) such as back-mixing and the accumulation of catalyst near the wall, resulting in over-cracking of hydrocarbons and excessive formation of coke, hydrogen, methane and ethane, do not allow the production of olefins to be promoted under high severity conditions.

[0009] To overcome these drawbacks, the HS-FCC process uses a downflow reactor, where the catalyst and feedstock are moved under gravity with a flow approaching that of a plug flow. The downward gas-solid flow in a reactor avoids backmixing and overcracking of products while the use of high C / O ratios ensures the predominance of catalytic reactions. The high temperature favors the formation of reaction intermediates such as light olefins while a controlled and short contact time avoids side reactions that are responsible for the consumption of such intermediates.

[0010] On the other hand, the downward gas-solid flow presents several major technological challenges, one of which is the flow in the mixing chamber. Indeed, the initial mixing between catalyst and feed determines the vaporization of hydrocarbons and the gas-solid contact throughout the downflow reactor. The initial mixing is generally carried out in a fraction of a second with, for a typical HS-FCC, a flow rate of the order of 400 to 700 t / h of feed and 7000 to 21000 t / h of catalyst, which requires efficient technology to have a mixing chamber that approaches a perfectly stirred zone.

[0011] Patent FR 2 753 453 B1 describes a downflow cracking reactor comprising a contact zone between the hydrocarbons and the catalyst in which the injectors are oriented so as to direct charge droplets counter-current to the downflow of catalyst particles, at an angle to the horizontal equal for example to 15°, but which can be between 2° and 45°.

[0012] Summary of the invention

[0013] In the context described above, a first object of the present invention is to overcome the problems of the prior art and to provide a device for fluidized bed catalytic cracking with descending gas-solid cocurrent with homogeneous catalyst flow, i.e., in which the solid concentration in the cross-section of the reactor is substantially uniform. Indeed, the device according to the invention makes it possible to obtain a homogeneous catalyst concentration between the central zone and the annular zone (i.e., in the proximity of the wall) of the descending gas-solid cocurrent reactor.

[0014] A second object of the present invention is to provide a device for downward gas-solid co-current fluidized bed catalytic cracking in which the catalyst concentration in the central zone is higher with less accumulation near the walls in the mixing chamber, resulting in better contact with the vaporized feedstock.

[0015] A third object of the present invention is to provide a device for descending gas-solid co-current fluidized bed catalytic cracking in which the arrangement of the injectors is optimized according to the C / O ratio. According to a first aspect, the aforementioned objects, as well as other advantages, are obtained by a device for descending gas-solid co-current fluidized bed catalytic cracking comprising, from top to bottom:

[0016] - a pipe suitable for transporting a downward flow of catalyst particles;

[0017] - a mixing chamber connected to the pipe and adapted to be supplied by the pipe in downward flow, the mixing chamber comprising at least a first hydrocarbon feed injector; and

[0018] - a descending gas-solid co-current fluidized bed reactor connected to the mixing chamber and adapted to be supplied by the mixing chamber with a mixture comprising catalyst particles and hydrocarbon feedstock, in which the at least one first injector has a predetermined angle α relative to the horizontal meeting the following two criteria:

[0019] - the resulting momentum vector, calculated from the vector sum of the charge momentum and the catalyst momentum, has an angle λ with respect to a horizontal plane of between 70° and 80°; and

[0020] - the ratio of the vertical component of the charge movement quantity and the catalyst movement quantity is between -0.2 and 0.1.

[0021] Advantageously, the device makes it possible to homogenize the concentration of catalyst particles along the fluidized bed reactor. Advantageously, the device makes it possible to improve the contact between the catalyst and the vaporized feedstock. Advantageously, the device makes it possible to optimize the arrangement and orientation of the injectors according to the operating conditions envisaged.

[0022] According to one or more embodiments, the mixing chamber comprises between 2 and 12 first injectors, preferably between 3 and 8 first injectors.

[0023] According to one or more embodiments, the resulting momentum vector has an angle λ with respect to a horizontal plane of between 72° and 77°; and / or the ratio of the vertical component of the charge momentum vector and the catalyst momentum is between -0.13 and 0.04.

[0024] According to one or more embodiments, the first injectors are arranged counter-current to the downward flow at an angle α of between 15° and 45° relative to the horizontal. According to one or more embodiments, at least one first injector has an orientation offset from the diameter of the mixing chamber at an angle θ greater than 0° and less than or equal to 45°, and preferably between 10° and 20°.

[0025] According to one or more embodiments, first injectors are arranged in one or more horizontal rows.

[0026] According to one or more embodiments, the mixing chamber comprises at least one second diluent injector.

[0027] According to one or more embodiments, the second injectors have an angle p relative to the horizontal of between 0° and 80°, and preferably between 10° and 45°.

[0028] According to one or more embodiments, second injectors are arranged in one or more horizontal rows.

[0029] According to one or more embodiments, the radial position of second injectors is in a separation space between adjacent radial positions of two first injectors.

[0030] According to one or more embodiments, the radial position of at least one second injector is arranged relative to the radial position of a first adjacent injector at an angle 5 substantially equal to half of the separation angle y between two first adjacent injectors.

[0031] According to one or more embodiments, at least one second injector has an orientation offset from the diameter of the mixing chamber at an angle o greater than 0° and less than or equal to 45°, and preferably between 10° and 20°.

[0032] According to one or more embodiments, at least a portion of the mixing chamber comprises a central spacer disposed substantially along a central / vertical axis of the mixing chamber and defining an annular orifice of the mixing chamber, through which catalyst particles discharge and / or flow into the mixing chamber.

[0033] According to a second aspect, the aforementioned objects, as well as other advantages, are obtained by a process for descending gas-solid co-current fluidized bed catalytic cracking comprising the following steps:

[0034] - transport a downward flow of catalyst particles in a (vertical) pipe;

[0035] - feeding a mixing chamber through the (vertical) pipe with the descending flow, the mixing chamber comprising at least a first hydrocarbon feed injector; - feeding a descending gas-solid co-current fluidized bed reactor through the mixing chamber with a mixture comprising catalyst particles and hydrocarbon feed; and

[0036] - at least partially cracking the hydrocarbon feedstock in the presence of the catalyst particles in the descending gas-solid co-current fluidized bed reactor, to produce an effluent comprising at least partially coked catalyst and gaseous cracking products, in which the at least one first injector has a predetermined angle α relative to the horizontal meeting the following two criteria:

[0037] - the vector of the resulting momentum, calculated from the vector sum of the momentum of the charge and the momentum (vertical and downward) of the catalyst, has an angle λ with respect to a horizontal plane of between 70° and 80°; and

[0038] - the ratio of the vertical component of the quantity of charge movement and the quantity of movement (vertical and downward) of catalyst, is between -0.2 and 0.1.

[0039] According to one or more embodiments, the method comprises at least one of the following operating conditions:

[0040] - The catalyst particles comprise a matrix made of clay, silica or silica alumina, optionally binder, optionally dopant, and / or zeolite, for example from 15% to 70% by weight of zeolite relative to the weight of the catalyst, preferably a Y zeolite and / or a ZSM-5 zeolite, very preferably a ZSM-5 zeolite, optionally doped;

[0041] - the grain density of the catalyst particles is between 1000 kg / m 3 and 2000 kg / m 3 , preferably between 1250 kg / m 3 and 1750 kg / m 3 .

[0042] - the hydrocarbon feedstock is a hydrocarbon feedstock with a boiling point greater than or equal to 340°C or a hydrocarbon feedstock with a boiling point less than or equal to 450°C;

[0043] - the downward flow of catalyst particles in the (vertical) pipe upstream of the mixing chamber is in dense fluidized regime and preferably with a mass flow greater than 200 kg / m 2 s ;

[0044] - reactor outlet temperature between 520°C and 750°C and preferably less than 650°C; absolute total pressure between 0.1 MPa and 0.5 MPa; - mass ratio of the catalyst to the hydrocarbon feedstock C / O between 5°(kg / h) / (kg / h) and 35 (kg / h) / (kg / h) and preferably between 15 (kg / h) / (kg / h) and 30 (kg / h) / (kg / h);

[0045] - contact time te between the hydrocarbon feedstock and the catalyst less than 10 seconds, preferably between 0.5 seconds and 4 seconds;

[0046] - mass flow of catalyst particles between 50 and 850 kg / (m 2 s), preferably between 400 and 750 kg / (m 2 s);

[0047] - gas surface velocity between 2 m / s and 26 m / s, preferably between 6 m / s and 16 m / s;

[0048] - injection of diluent by the first injector and / or at least one second injector at a rate of a quantity representing 0% or 0.1% to 40% by weight, preferably 1% to 35% by weight and preferably between 1% and 30% by weight relative to the mass of the hydrocarbon feedstock.

[0049] Other characteristics and advantages of the invention of the aforementioned aspects will appear on reading the description below and non-limiting examples of embodiments, with reference to the figures appended and described below.

[0050] List of figures

[0051] Figure 1 shows a sectional diagram of an FCC device according to one or more embodiments of the present invention comprising injectors for homogenizing the catalyst flow.

[0052] Figure 2 shows a schematic and cross-sectional view showing the fluid flow in the mixing chamber of an FCC device according to one or more embodiments of the present invention.

[0053] Figure 3 shows a schematic top view of the mixing chamber of an FCC device according to one or more embodiments of the present invention.

[0054] Figure 4 shows 3D views of an FCC device according to one or more embodiments of the present invention.

[0055] Figure 5 shows 3D views of a schematic A of a reference FCC device, and a schematic B of an FCC device according to one or more embodiments of the present invention.

[0056] Figure 6 shows 3D views of diagrams A and B of the time-averaged catalyst volume fraction in the reference FCC device of Figure 5, and in the inventive FCC device of Figure 5, respectively. Figure 7 shows the radial profiles A and B of the solid fraction and solid mass flux at 2.8 m below the injectors of the reference FCC device of Figure 5, and of the inventive FCC device of Figure 5, respectively.

[0057] Detailed description of the invention

[0058] Embodiments according to the foregoing aspects will now be described in detail. In the following detailed description, numerous specific details are set forth in order to provide a more thorough understanding of the device and method according to the present invention. However, it will be apparent to those skilled in the art that the device may be implemented without these specific details. In other instances, well-known features have not been described in detail to avoid unnecessarily complicating the description.

[0059] In this specification, the term "comprise" is synonymous with (means the same as) "comprise", "include" and "contain", and is inclusive or open and does not exclude other elements not recited. It is understood that the term "comprise" includes the exclusive and closed term "consist". Furthermore, in this specification, the terms "essentially" or "substantially" or "about" correspond to an approximation of ± 10%, preferably ± 5%, very preferably ± 1%.

[0060] The invention relates to a fluidized bed catalytic cracking device and method for the chemical transformation of petroleum products (FCC), used for example for high severity catalytic cracking (HS-FCC).

[0061] An FCC unit generally processes a hydrocarbon cut (called heavy) from the vacuum distillation unit such as a vacuum gas oil or a vacuum residue, or an atmospheric residue, alone or in a mixture. An FCC unit can also process a hydrocarbon cut (called light) such as a gasoline cut or a diesel cut, alone or in a mixture. It is also possible to process a mixture of light and heavy hydrocarbon cuts, or even a complete crude. In order to increase propylene and ethylene yields by using high severity reaction conditions (high temperature, very short contact times, high C / O ratios between the catalyst flow C and the feed O flow), catalytic cracking devices and processes generally use a downflow reactor with a gas-solid cocurrent flow (downer or downflow reactor according to English terminology), hereinafter referred to as a downflow reactor.

[0062] However, the downward gas-solid flow presents several technological challenges, including achieving homogeneous flow and mixing in the established flow section of the downflow reactor. In order to overcome these drawbacks, improvements to the downflow reactor technology described in patent FR 2 753 453 B1 have been identified, to address the challenge presented above through a specific arrangement of hydrocarbon feedstock injectors, and optionally diluent injectors, to improve the contact between the catalyst and the hydrocarbons in the mixing chamber.

[0063] The device according to the invention

[0064] Referring to Figure 1, the device according to one or more embodiments of the present invention comprises from top to bottom:

[0065] - a pipe 1 (substantially vertical);

[0066] - a mixing chamber 2; and

[0067] - a downward flow reactor 3 (substantially vertical).

[0068] Line 1 is adapted to supply mixing chamber 2 with solid catalyst (particles). Line 1 mainly transports solid, as well as a fluidization gas entrained by the descending solid. Line 1 has a flow like a feed column ("standpipe" according to English terminology) well known to those skilled in the art.

[0069] The mixing chamber 2 is connected to the line 1 and is adapted to feed the downflow reactor 3 with a mixture comprising catalyst particles, a hydrocarbon feedstock and optionally a diluent.

[0070] The downflow reactor 3 is connected to the mixing chamber 2 and is adapted to at least partially crack the hydrocarbon feedstock in the presence of the catalyst particles to produce an effluent comprising at least partially coked catalyst and gaseous cracking products, and optionally unconverted vaporized feedstock.

[0071] Specifically, with reference to Figure 1, the pipe 1 feeds the mixing chamber 2 with a downward flow 4 of (hot) catalyst particles, the mixing chamber 2 comprising one or more first injectors 5 of hydrocarbon feedstock 6. According to one or more embodiments, the first injector(s) 5 is adapted to inject diluent (e.g. water vapor) with the feedstock. According to one or more embodiments, the mixing chamber 2 comprises one or more second injectors 7 of diluent 8. In the mixing chamber 2, the downward flow 4 comes into contact with the hydrocarbon feedstock 6 atomized using the first injector(s) 5 and optionally with diluent 8, introduced for example by the second injector(s) 7. Advantageously, the injection of diluent 8 makes it possible to reduce the partial pressure of the hydrocarbon feedstock and to reduce secondary reactions.Advantageously, the injection of diluent 8 makes it possible to improve the atomization of the hydrocarbon feedstock 6. According to one or more embodiments, the diluent 8 is chosen from the group consisting of water vapor, nitrogen, CO2, light hydrocarbons (e.g. C1-C5 compounds), combustion fumes. According to one or more embodiments, the diluent 8 comprises or consists of water vapor.

[0072] According to one or more embodiments, the pipe 1 has a constant cross-section geometry, such as cylindrical, square, rectangular or hexagonal, or a variable cross-section geometry, such as a truncated pyramid or cone, or a combination of the different geometric shapes. According to one or more embodiments, the pipe 1 has a cylindrical shape and optionally a variable diameter. According to one or more embodiments, the pipe 1 has an at least partially frustoconical shape. According to one or more embodiments, the pipe 1 comprises (in the direction of flow of the solid catalyst): a cylindrical section, for example the diameter of which is chosen to obtain a solid flow of 100 to 800 kg / (m 2 s) and preferably between 300 and 600 kg / (m 2s); a truncated section (called a narrowing section) adjacent to the mixing chamber 2, the diameter of which decreases, for example in order to achieve a solid flow, without taking into account the internals, between 400 and 2000 kg / (m 2 s) and preferably between 700 and 1500 kg / (m 2 s); and optionally a second cylindrical section, for example whose diameter is chosen to obtain a solid flow, without taking into account the internals, between 400 and 2000 kg / (m 2 s) and preferably between 700 and 1500 kg / (m 2 s).

[0073] According to one or more embodiments, the mixing chamber 2 is of constant cross-section geometry, such as cylindrical, square, rectangular or hexagonal, or of variable cross-section, such as a truncated pyramid or cone, or a combination of the different geometric shapes. The mixing chamber may be provided with central internals, such as a central space-saving part described below with reference to Figure 5. According to one or more embodiments, the mixing chamber 2 is of cylindrical shape and optionally of variable diameter. According to one or more embodiments, the mixing chamber 2 is of at least partially truncated cone shape.According to one or more embodiments, the mixing chamber 2 comprises an upper limit of section S1 connecting the mixing chamber 2 to the conduit 1 and a lower limit of section S2 connecting the mixing chamber 2 to the downflow reactor 3, the ratio S1 / S2 being less than 0.9 and preferably less than 0.7. According to one or more embodiments, the ratio S1 / S2 is between 0.4 and 0.9, preferably between 0.5 and 0.7.

[0074] According to one or more embodiments, the mixing chamber 2 comprises between 2 and 12 first injectors 5, preferably between 3 and 8 first injectors 5. With reference to Figures 1 and 2, the applicant has identified that the axial direction of the first injectors 5 is a key element for properly dispersing the catalyst. Specifically according to the invention, the first injectors 5 have a predetermined angle a (alpha) relative to the horizontal meeting the following two criteria:

[0075] - the vector of the quantity of the resulting movement M tot , calculated from the vector sum of the momentum (defined as mass (or mass flow rate) * velocity) of charge M6 and the momentum of catalyst M4, has an angle λ (lambda) relative to the horizontal between 70° and 80° and preferably between 72° and 77°; and

[0076] - the ratio of the vertical component of the vector of the quantity of charge movement Mev and the quantity of catalyst movement M4, is between -0.2 and 0.1 and preferably between -0.13 and 0.04.

[0077] Compliance with the two criteria mainly gives axial directions of the first injectors 5 in counter-current to the descending flow 4, for example at an angle α between 0° and 80°, or slightly in co-current to the descending flow 4, for example at an angle α between -20° and 0°. According to one or more embodiments, the first injectors 5 are arranged counter-current to the descending flow 4 at an angle α between 15° and 45° relative to the horizontal.

[0078] Furthermore, with reference to Figure 3, to promote turbulence in the mixing chamber 2 and direct the feed to areas with higher catalyst concentration, at least one first injector 5 may have an orientation (according to a projection on a horizontal plane) offset relative to the diameter of the mixing chamber 2 at an angle θ (theta) greater than 0° and less than or equal to 45°, and preferably between 10° and 20°. According to one or more embodiments, adjacent first offset injectors 5 have respectively positive and negative angles θ, in particular to improve turbulence.

[0079] With reference to Figure 4, according to one or more embodiments, first injectors 5 are arranged in one or more horizontal rows, i.e., perpendicular to the central / vertical axis Z of the pipe 1, of the mixing chamber 2 and of the downflow reactor 3. According to one or more embodiments, the adjacent first injectors 5 of a row of first injectors 5 are arranged on the wall of the mixing chamber 2 according to a separation angle y (gamma) being substantially equal to 360° divided by the number of first injectors 5 of said row.

[0080] According to one or more embodiments, the mixing chamber 2 comprises between 2 and 12 second injectors 7, preferably between 3 and 8 second injectors 7. With reference to FIG. 1, the second injectors 7 have an angle p (beta) relative to the horizontal of between 0° and 80°, and preferably between 10° and 45°.

[0081] With reference to Figure 4, according to one or more embodiments, second injectors 7 are arranged in one or more horizontal rows (perpendicular to the central / vertical axis Z).

[0082] With reference to figure 4, according to one or more embodiments, second injectors 7 are arranged below (eg a row) first injectors 5. According to one or more embodiments, second injectors 7 are arranged between two rows of first injectors 5.

[0083] With reference to figures 3 and 4, according to one or more embodiments, the radial position of second injectors 7 is in a separation space between the adjacent radial positions of two first injectors 5. According to one or more embodiments, the radial position of at least one second injector 7 is arranged relative to the radial position of a first injector 5 adjacent to a second injector 7 (according to a projection on a horizontal plane) at an angle 5 (delta) substantially equal to half the separation angle y between two adjacent first injectors 5.

[0084] With reference to Figures 3 and 4, to promote turbulence in the mixing chamber 2 and direct the catalyst towards areas with higher charge concentration, the second injectors 7 may have an orientation (according to a projection on a horizontal plane) offset from the diameter of the mixing chamber by an angle o (sigma) greater than 0° and less than or equal to 45°, and preferably between 10° and 20°. To make the top view of Figure 4 clearer, one row of injectors 5 has been removed.

[0085] With reference to Figure 1, the mixing chamber 2 feeds the downflow reactor 3 with a mixture of hydrocarbon feedstock 6, catalyst particles and optionally diluent 8. Advantageously, the hydrocarbon feedstock 6 and the catalyst particles give rise to the cracking reactions which complete each other in the downflow reactor 3 of a height L (along the central / vertical axis Z) to produce a hydrocarbon effluent 9 comprising cracking products, spent catalyst and potentially a portion of the unreacted hydrocarbon feedstock.

[0086] With reference to Figure 5, according to one or more embodiments, at least a portion of the mixing chamber 2 comprises a central spacer piece 10 ("plug" according to English terminology) arranged substantially along the central / vertical axis Z and defining an annular orifice 11 of the mixing chamber 2, through which the catalyst particles pour and / or flow into the mixing chamber 2. According to one or more embodiments, the vertical position of the first injectors 5 and / or the second injectors 7 is between the upper end and the lower end of the central spacer piece 10, i.e., the feedstock 6 and optionally the diluent 8 are introduced into the annular orifice 11 of the mixing chamber 2.

[0087] According to one or more embodiments, the downflow reactor 3 is of constant cross-section geometry, such as cylindrical, square, rectangular or hexagonal, preferably cylindrical. According to one or more embodiments, the downflow reactor 3 is of cylindrical shape and optionally of variable diameter. According to one or more embodiments, the diameter of the downflow reactor 3 is defined such that the superficial velocity of the gas passing through it is between 2 m / s and 26 m / s, preferably between 6 m / s and 16 m / s.

[0088] The catalyst

[0089] The catalyst is a solid catalyst (e.g. particles of density, size and grain shape chosen for use in a fluidized bed). The densities, sizes and shapes of fluidized bed catalysts are known to those skilled in the art and will not be described further. The catalyst may be any type of catalytic cracking catalyst.

[0090] According to one or more embodiments, the catalyst is an FCC type catalyst, containing for example what is commonly called a matrix made of clay, silica or silica alumina, optionally binder, and / or zeolite, for example from 15% to 70% by weight of zeolite relative to the weight of the catalyst, preferably a Y zeolite and / or a ZSM-5 zeolite. According to one or more embodiments, the catalyst comprises a ZSM-5 zeolite. According to one or more embodiments, the grain density of the catalyst is between 1000 kg / m 3 and 2000 kg / m 3 . According to one or more embodiments, the grain density of the catalyst is between 1250 kg / m 3 and 1750 kg / m 3 .

[0091] According to one or more embodiments, the catalyst comprises at least one binder (eg from 30% to 85% by weight) chosen from alumina, silica, silica-alumina, magnesia, titanium oxide, zirconia, clays and boron oxide, alone or as a mixture and preferably from silica, silica-alumina and clays, alone or as a mixture.

[0092] According to one or more embodiments, the catalyst comprises at least one doping element (eg from 0 to 10% by weight) chosen from phosphorus, magnesium, sodium, potassium, calcium, iron, boron, manganese, lanthanum, cerium, titanium, tungsten, molybdenum, copper, zirconium and gallium, alone or as a mixture.

[0093] According to one or more embodiments, the catalyst comprises and / or consists of zeolite, such as ZSM-5, optionally doped. The feedstock

[0094] According to one or more embodiments, the hydrocarbon feedstock 6 is a hydrocarbon feedstock (called heavy), characterized by a boiling onset temperature of substantially 340°C, or even greater than 340°C, often greater than 380°C, such as a heavy hydrocarbon cut, for example from a vacuum distillation unit, such as vacuum gas oil / distillate (“vacuum gas oil” or “VGO” according to English terminology) or a vacuum residue, an atmospheric residue, a vacuum gas oil from a conversion unit, such as a coker gas oil (“Heavy Coker Gas Oil” or “HCGO” according to English terminology) or a heavy hydrocarbon cut from an ebullated bed or entrained bed hydroconversion unit (such as the H-Oil, LC-Fining, EST, VCC or Uniflex processes), a recycle from a hydrocracking step, alone or in mixture.

[0095] According to one or more embodiments, the hydrocarbon feedstock 6 is a so-called light feedstock, characterized by an end-of-boiling temperature of less than or equal to 450°C, often less than 400°C, such as a gasoline cut or a diesel cut, for example from an atmospheric distillation unit, or from a conversion unit, such as a gasoline or a diesel from a hydrocracking unit, or a gasoline or a diesel from a coking unit or a gasoline or a diesel from an ebullated bed or entrained bed hydroconversion unit (such as the H-Oil, LC-Fining, EST, VCC or Uniflex processes), or a gasoline or a diesel from an FCC unit, or a recycle from the FCC unit in question, alone or as a mixture. According to one or more embodiments, it is also possible to process a mixture of light and heavy hydrocarbon cuts, or even a complete crude.

[0096] Upon contact with the descending flow 4 of hot catalyst particles, the pulverized hydrocarbon feedstock 6 vaporizes and endothermic cracking reactions occur along the descending flow reactor 3, thus reducing the temperature and producing:

[0097] - recoverable products (e.g. C1-C4 gas including olefins; a gasoline cut including aromatics);

[0098] - optionally a light diesel cut (“Light Cycle Oil” or LCO in Anglo-Saxon terminology) 0 ;

[0099] - optionally a heavy diesel cut (“Heavy Cycle Oil” or HCO in Anglo-Saxon terminology);

[0100] - optionally an oil in the form of slurry; and optionally a solid residue (coke) adsorbed on the catalyst. The process according to the invention

[0101] The process according to the present invention comprises a catalytic cracking step for the production of light olefins (and in particular ethylene and propylene), aromatics (and in particular benzene, toluene and xylenes), and gasoline (and optionally LCO, HCO and slurry), by catalytic cracking of the hydrocarbon feedstock 6 (fed by the first injector 5) by contacting with the descending flow 4 of hot catalyst particles (fed by the line 1), and optionally the diluent 8 (fed by the second injector 7) in the mixing chamber 2 then in the descending flow reactor 3.

[0102] According to one or more embodiments, the downward flow 4 of the catalyst particles in the pipe 1 upstream of the mixing chamber 2 is in a dense fluidized regime and preferably with a mass flow greater than 200 kg / m 2 s, for example to preferably allow a regime with descending bubbles.

[0103] In this application, the term "dense fluidized bed" means a gas-solid fluidized bed operating in a homogeneous regime, in a bubbling regime or in a turbulent regime.

[0104] In this application, the term "homogeneous fluidized bed" means a gas-solid fluidized bed whose gas velocity is between the minimum fluidization velocity and the minimum bubbling velocity. These velocities depend on the properties of the solid catalyst (density, size, grain shape, etc.). The solid volume fraction is between a value close to 0.45 and the maximum solid volume fraction corresponding to a fixed, non-fluidized bed, generally close to 0.6.

[0105] In this application, the term "bubbling fluidized bed" means a gas-solid fluidized bed whose gas velocity is between the minimum bubbling velocity and the transition velocity to the turbulent regime. These velocities depend on the properties of the solid catalyst (density, size, grain shape, etc.). The volume fraction of solid is between a value close to 0.35 and a value close to 0.45.

[0106] In this application, the term "turbulent fluidized bed" means a gas-solid fluidized bed whose gas velocity is between the transition velocity to the turbulent regime and the transport velocity. The volume fraction of solid is between a value close to 0.25 and a value close to 0.35.

[0107] In this application, the term "transported fluidized bed" means a gas-solid fluidized bed whose gas velocity is greater than the transport velocity. The solid volume fraction is less than a value close to 0.25. In this application, the term "transport velocity" corresponds to the velocity with which essentially all of the solid is entrained by the gas.

[0108] According to one or more embodiments, the injectors 5 are adapted to atomize the hydrocarbon feedstock 6 (liquid) and penetrate the catalyst flow.

[0109] According to one or more embodiments, the operating conditions of the pipe 1 and / or the downflow reactor 3 are chosen from the following conditions:

[0110] - temperature (reactor outlet) between 520°C and 750°C and preferably less than 650°C;

[0111] - absolute total pressure between 0.1 MPa and 0.5 MPa;

[0112] - mass ratio of catalyst 4 to hydrocarbon feedstock 6 C / O between 5 (kg / h) / (kg / h) and 35 (kg / h) / (kg / h) and preferably between 15 (kg / h) / (kg / h) and 30 (kg / h) / (kg / h);

[0113] - contact time t c between the hydrocarbon feedstock 6 and the catalyst less than 10 seconds, preferably between 0.5 seconds and 4 seconds;

[0114] - mass flow of catalyst particles between 50 and 850 kg / (m 2 s), preferably between 400 and 750 kg / (m 2 s); and

[0115] - gas surface velocity between 2 m / s and 26 m / s, preferably between 6 m / s and 16 m / s.

[0116] In this description, the contact time t c is defined as the product of the solid volume fraction E S by bed height H s(eg reactor height L), divided by the superficial gas velocity vsg, this integrated throughout the bed height, as defined below in the mathematical formula Math 1.

[0117] Math 1

[0118] According to one or more embodiments, a quantity of diluent 8 (e.g. nitrogen and / or water vapor) is added to the feedstock to reduce the partial pressure of hydrocarbons in the feedstock and the diluent is introduced in an amount representing 0% or 0.1% to 40% by weight, preferably 1% to 35% by weight and preferably between 1% and 30% by weight relative to the mass of the hydrocarbon feedstock 6.

[0119] According to one or more embodiments, at the end of the catalytic cracking step in the downflow reactor 3, the gaseous products and the catalyst, and optionally the unconverted vaporized feedstock, are separated in the gas / solid separator (not shown) containing a dense fluidized bed where the cracking reactions can continue.

[0120] According to one or more embodiments, the operating conditions of the separator are chosen from the following conditions:

[0121] - temperature (reactor outlet) between 500°C and 750°C, preferably between 550°C and 700°C, even more preferably between 580°C and 685°C;

[0122] - absolute total pressure between 0.1 MPa and 0.5 MPa and preferably between 0.1 MPa and 0.4 MPa and more preferably between 0.1 MPa and 0.3 MPa;

[0123] - mass ratio of catalyst to feedstock (unconverted vaporized feedstock and gaseous products) C / O between 5 (kg / h) / (kg / h) and 40 (kg / h) / (kg / h);

[0124] - contact time t c between the charge and the catalyst between 500 milliseconds (ms) and 10 seconds; and

[0125] - partial pressure of the hydrocarbons in the charge (PPHcharge) between 0.01 MPa and 0.3 MPa, preferably between 0.02 MPa and 0.2 MPa and more preferably between 0.05 MPa and 0.15 MPa.

[0126] According to one or more embodiments, at the outlet of the separator the coked catalyst is sent to an optional stripper (not shown) to strip the hydrocarbons remaining adsorbed on the surface of the catalyst using a second diluent.

[0127] According to one or more embodiments, the operating conditions of the stripper are chosen from the following conditions:

[0128] - residence time of the catalyst in the stripper: between 10 seconds and 180 seconds, preferably between 30 seconds and 120 seconds;

[0129] - superficial gas velocity between the minimum fluidization velocity and the transition velocity to turbulent regime, for example between 0.01 m / s and 0.5 m / s, preferably between 0.15 m / s and 0.4 m / s;

[0130] - solid flow between 25 kg / m 2 s and 200 kg / m 2 s, preferably between 50 kg / m 2 s and 150 kg / m 2 s and preferably between 50 kg / m 2 s and 100 kg / m 2 s ;

[0131] - temperature between 500°C and 750°C, preferably between 550°C and 650°C;

[0132] - absolute total pressure between 0.1 MPa and 0.5 MPa and preferably between 0.1 MPa and 0.4 MPa and more preferably between 0.1 MPa and 0.3 MPa;

[0133] - solid volume fraction between 0.25 and 0.6, preferably between 0.4 and 0.6. According to one or more embodiments, at the outlet of the separator or stripper, the coked solid is transported into a regenerator (not shown) in which an air supply burns the coke of the catalyst to produce a hot regenerated catalyst and combustion gases, the hot regenerated catalyst being able to supply the descending flow 4 with hot catalyst particles.

[0134] According to one or more embodiments, the operating conditions of the regenerator are chosen from the following conditions:

[0135] - gas surface velocity between 0.1 m / s and 2 m / s, preferably 0.2 m / s and 1.5 m / s;

[0136] - catalyst residence time between 30 seconds and 20 minutes, preferably between 1 minute and 10 minutes;

[0137] - temperature between 500°C and 840°C, preferably between 650°C and 750°C.

[0138] Examples

[0139] With reference to Figure 5, the flows in a reference device A and a device according to the invention B operating under reaction-free conditions were compared in order to study the hydrodynamics.

[0140] Reference device A includes:

[0141] - a pipe 1, composed of a cylindrical section, a narrowing cone and a cylindrical section;

[0142] - a truncated mixing chamber 2 (S1 / S2 being less than 1) comprising a central space-saving part 10 defining an annular orifice 11;

[0143] - a cylindrical downflow reactor 3 with a length of 4.07 m and an internal diameter of 0.42 m;

[0144] - four first injectors 5 of hydrocarbon charge 6 positioned in co-current with the descending flow 4 of catalyst particles with an angle of 45° downwards relative to the horizontal direction, which produces an angle Δ of the vector of the quantity of the resulting movement M tot 79° to the horizontal. The ratio of the vertical component of the amount of charge movement M 6v and the catalyst movement quantity M4 is 0.23 which is outside the recommended range; and four second injectors 7 of diluent 8 (water vapor) positioned in co-current with the descending flow 4 of catalyst particles with an angle of 45° downwards relative to the horizontal direction. The device according to the invention B comprises:

[0145] - a pipe 1, composed of a cylindrical section, a narrowing cone and a cylindrical section;

[0146] - a truncated mixing chamber 2 (S1 / S2 being less than 1) comprising a central space-saving part 10 defining an annular orifice 11;

[0147] - a cylindrical downflow reactor 3 with a length of 4.07 m and an internal diameter of 0.42 m;

[0148] - four first injectors 5 of hydrocarbon charge 6 positioned in counter-current to the descending flow 3 of catalyst particles with an angle a of 30° upwards relative to the horizontal direction, which produces an angle A of the vector of the quantity of the resulting movement M tot 72° to the horizontal. The ratio of the vertical component of the charge momentum Mev and the catalyst momentum M4 is -0.16; and

[0149] - four second injectors 7 of diluent 8 (water vapor) positioned counter-current to the descending flow 3 of catalyst particles with an angle p of 30° upwards relative to the horizontal direction.

[0150] The configurations of the reference device A and the device according to the invention B were simulated in CFD with the Barracuda© tool under the following operating conditions:

[0151] - the catalyst flow of 607 kg / m 2 s ;

[0152] - the catalyst has a diameter dso of 73 pm and a grain density of 1418 kg / m 3 (ie, group A of the Geldart classification);

[0153] - the air flow of 1.85 kg / s has a ratio between the first injectors 5 and the second injectors 7 of 70 / 30;

[0154] - the first injectors 5 are positioned 0.2 m above the second injectors 7;

[0155] - the angle 5 of rotation between the first injectors 5 and the second injectors 7 is 45°;

[0156] - the gas speed at the outlet of the injectors is 90 m / s for the first injectors 5 and 76 m / s for the second injectors 7;

[0157] - the flow is under ambient conditions without reaction;

[0158] - a central spacer 10 is positioned in the center of the mixing chamber 2.

[0159] Figure 6 shows the Particle Volume Fraction, denoted FVP, for the two configurations A and B of the reference device A and the device according to the invention B, respectively, over 13 sections. The first two sections are respectively at the height of the first and second injectors 5 and 7, and the following sections are spaced 0.35 m apart. Advantageously, the radial distribution of the solid throughout the downflow reactor 3 is always more homogeneous for the device according to the invention B compared to the reference device A. In addition, a significant concentration of the solid should be noted near the wall for the reference device A compared to the device according to the invention B. Figure 7 shows the radial profiles A and B of the particle volume fraction FVP, and of the Particle Mass Flux, denoted FM P, of the reference device A and the device according to the invention B of Figure 5, respectively.The radial profiles A and B are made in an x ​​direction (perpendicular to the central / vertical axis Z) at a height of 2.8 m below the first injectors 5. It can be noted that the device according to the invention B produces a more homogeneous radial profile B with a better distribution of the phases. The coefficient of variation of the volume fraction values ​​of the FVP particles on these radial profiles A and B is 40% for the reference device A and 15% for the device according to the invention B. Equivalently, the coefficient of variation of the mass flux values ​​of the FMP particles for the profiles A and B is 59% for the reference device A and 16% for the device according to the invention B, which indicates a better dispersion of the catalyst on the section for the device according to the invention B.

Claims

Claims 1. Process for fluidized bed catalytic cracking with descending gas-solid cocurrent comprising the following steps: - transport a downward flow (4) of catalyst particles in a vertical pipe (1); - feed a mixing chamber (2) through the vertical pipe (1) with the downward flow (4), the mixing chamber (2) comprising at least one first injector (5) of hydrocarbon feedstock (6); - feeding a descending gas-solid co-current fluidized bed reactor (3) through the mixing chamber (2) with a mixture comprising catalyst particles and hydrocarbon feedstock; and - at least partially cracking the hydrocarbon feedstock (6) in the presence of the catalyst particles in the descending gas-solid co-current fluidized bed reactor (3), to produce an effluent (9) comprising at least partially coked catalyst and gaseous cracking products, in which the at least one first injector (5) has a predetermined angle a relative to the horizontal meeting the following two criteria: - the vector of the quantity of the resulting movement (M tot ), calculated from the vector sum of the charge momentum (Me) and the vertical and downward catalyst momentum (M4), has an angle λ with respect to a horizontal plane of between 70° and 80°; and - the ratio of the vertical component of the quantity of charge movement (Mev) and the quantity of vertical and downward movement of catalyst (M4), is between -0.2 and 0.

1.

2. Method according to claim 1, wherein the mixing chamber (2) comprises between 2 and 12 first injectors (5), preferably between 3 and 8 first injectors (5).

3. A method according to claim 1 or claim 2, wherein the resulting momentum vector (M tot ) has an angle Δ with respect to a horizontal plane of between 72° and 77°; and / or the ratio of the vertical component of the vector of the quantity of charge movement (Mev) and the quantity of vertical and downward movement of catalyst (M4), is between -0.13 and 0.

04.

4. Method according to any one of the preceding claims, in which the first injectors (5) are arranged counter-current to the downward flow (4) at an angle α of between 15° and 45° relative to the horizontal.

5. Method according to any one of the preceding claims, in which at least one first injector (5) has an orientation offset from the diameter of the mixing chamber (2) at an angle 0 greater than 0° and less than or equal to 45°, and preferably between 10° and 20°.

6. Method according to any one of the preceding claims, in which first injectors (5) are arranged in one or more horizontal rows.

7. Method according to any one of the preceding claims, wherein the mixing chamber (2) comprises at least one second injector (7) of diluent (8).

8. Method according to claim 7, in which the second injectors (7) are arranged counter-current to the downward flow (4) and have an angle p relative to the horizontal of between 0° and 80°, and preferably between 10° and 45°.

9. Method according to claim 7 or claim 8, in which second injectors (7) are arranged in one or more horizontal rows.

10. Method according to any one of claims 7 to 9, wherein the radial position of second injectors (7) is in a separation space between adjacent radial positions of two first injectors (5).

11. Method according to any one of claims 7 to 10, in which the radial position of at least one second injector (7) is arranged relative to the radial position of an adjacent first injector (5) at an angle 5 substantially equal to half of the separation angle y between two adjacent first injectors (5).

12. Method according to any one of claims 7 to 11, in which at least one second injector (5) has an orientation offset from the diameter of the mixing chamber (2) at an angle o greater than 0° and less than or equal to 45°, and preferably between 10° and 20°.

13. A method according to any one of the preceding claims, wherein at least a portion of the mixing chamber (2) comprises a central spacer (10) arranged substantially along a central / vertical axis (Z) of the mixing chamber (2) and defining an annular orifice (11) of the mixing chamber (2), through which the catalyst particles discharge and / or flow into the mixing chamber (2).

14. Method according to claim 1, comprising at least one of the following operating conditions: - the catalyst particles comprise a matrix made of clay, silica or silica alumina, optionally binder, optionally dopant, and / or zeolite, for example from 15% to 70% by weight of zeolite relative to the weight of the catalyst, preferably a Y zeolite and / or a ZSM-5 zeolite, very preferably a ZSM-5 zeolite, optionally doped; - the grain density of the catalyst particles is between 1000 kg / m 3 and 2000 kg / m 3 , preferably between 1250 kg / m 3 and 1750 kg / m 3 ; - the hydrocarbon feedstock (6) is a hydrocarbon feedstock with a boiling start temperature greater than or equal to 340°C or a hydrocarbon feedstock with a boiling end temperature less than or equal to 450°C; - the downward flow (4) of catalyst particles in the vertical pipe (1) upstream of the mixing chamber (2) is in dense fluidized mode and preferably with a mass flow greater than 200 kg / m 2 s ; - reactor outlet temperature between 520°C and 750°C and preferably less than 650°C; - absolute total pressure between 0.1 MPa and 0.5 MPa; - mass ratio of catalyst (4) to hydrocarbon feedstock (6) C / O between 5 (kg / h) / (kg / h) and 35 (kg / h) / (kg / h) and preferably between 15 (kg / h) / (kg / h) and 30 (kg / h) / (kg / h); contact time te between the hydrocarbon feedstock (6) and the catalyst less than 10 seconds, preferably between 0.5 seconds and 4 seconds; - mass flow of catalyst particles between 50 and 850 kg / (m 2 s), preferably between 400 and 750 kg / (m 2 s); - gas surface velocity between 2 m / s and 26 m / s, preferably between 6 m / s and 16 m / s; - injection of diluent (8) by the first injector (5) and / or at least one second injector (7) in an amount representing 0% or 0.1% to 40% by weight, preferably 1% to 35% by weight and preferably between 1% and 30% by weight relative to the mass of the hydrocarbon feedstock (6).

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