Gas-solid parallel flow down-flow fluidized bed catalytic cracking method adopting directional feeding injector

Abstract

The invention relates to a method for parallel flow gas-solid downward flow type fluid catalytic cracking, which adopts a vertical pipeline (1) for conveying a downward flow (4) of catalyst particles; a mixing chamber (2) comprising at least one first injector (5) for injecting a hydrocarbon feedstock (6); a co-current gas-solid down-flow fluidized bed reactor (3) fed with a catalyst and a hydrocarbon feedstock, said first injector having a predetermined angle [alpha] with respect to the horizontal plane such that: the vector of the resultant momentum (Mtot) (the vector sum of the momentum of the feedstock (M6) and the momentum of the catalyst (M4)) has an angle [lambda] of 70 DEG-80 DEG with respect to the horizontal plane; and the ratio of the vertical component (M6v) of the momentum vector of the feedstock to the vertical and downward momentum of the catalyst is-0.2 to 0.1.

Description

Technical Field

[0001] The present invention relates to the fields of oil refining and petrochemistry, and to methods and apparatuses for the chemical conversion of petroleum products, in particular hydrocarbon fractions, by fluid catalytic cracking (FCC) to produce light olefins (i.e., olefins containing 2 to 4 carbon atoms), and more specifically ethylene and propylene, as well as aromatic hydrocarbons (such as BTX), and more specifically p-xylene. Prior Art

[0002] The present invention consists in improving the design of the established flow regime in a co-current gas-solid downflow fluidized bed reactor ("downflow bed" or "downflow reactor") (hereinafter referred to as the downflow reactor), for example for high severity fluid catalytic cracking (HS-FCC).

[0003] Ethylene, propylene, butene, butadiene and aromatic hydrocarbons such as benzene, toluene and xylene (BTX) represent the basic products of the petrochemical industry. These products are usually obtained by catalytic reforming and / or thermal cracking (steam cracking) of hydrocarbons such as naphtha, kerosene or gas oil. These compounds are also obtained by fluid catalytic cracking (FCC) of hydrocarbons such as vacuum distillate (VD, or vacuum gas oil VGO) and / or hydrocarbons and / or (vacuum or atmospheric) residues resulting from the distillation of naphtha, gas oil and whole crude oil.

[0004] The high severity fluid catalytic cracking (HS-FCC) process aims to increase the yields of propylene and ethylene by means of high temperature reaction conditions, extremely short contact times (e.g., ~1 s), and a high catalyst mass flow rate C to feedstock mass flow rate O ratio (C / O).

[0005] Regarding the drawbacks of conventional co-current gas-solid upflow fluidized bed FCC reactors (or "risers"), such as backmixing and catalyst accumulation near the walls, leading to excessive cracking of hydrocarbons and the excessive formation of coke, hydrogen, methane and ethane, it is impossible to promote olefin production under high severity conditions.

[0006] To overcome these drawbacks, the HS-FCC process employs a downflow reactor in which the catalyst and the feedstock are set to move under the action of gravity, with a flow approximating plug flow. The downward gas-solid flow inside the reactor avoids backmixing and excessive cracking of the products, while the use of a high C / O ratio ensures the predominance of the catalytic reaction. The high temperature promotes the formation of reaction intermediates such as light olefins, while the controlled and short contact time avoids side reactions leading to the consumption of such intermediates.

[0007] However, the downward gas-solid flow presents many significant technical challenges, one of which corresponds to the flow in the mixing chamber. This is because the initial mixing between the catalyst and the feedstock determines the vaporization of hydrocarbons and the gas-solid contact throughout the downflow reactor. The initial mixing is typically completed within a fraction of a second, and for a typical HS-FCC, the feedstock flow rate is about 400 to 700 tons per hour and the catalyst flow rate is about 7000 to 21000 tons per hour, which requires efficient technology to obtain a mixing chamber close to a perfectly stirred zone.

[0008] Patent FR 2 753 453 B1 describes a downflow cracking reactor that includes a zone for contacting hydrocarbons with a catalyst, where the injector is oriented to direct the feedstock droplets countercurrent to the downward flow of the catalyst particles, at an angle of 15° with respect to the horizontal plane, but can be from 2° to 45°. Summary of the Invention

[0010] In the above context, a first object of the present invention is to overcome the problems of the prior art and provide a device for co-current gas-solid downflow fluidized catalytic cracking with a uniform catalyst flow, i.e., where the solid concentration in the reactor cross-section is substantially uniform. Specifically, the device according to the present invention enables a uniform catalyst concentration to be obtained between the central region and the annular region (i.e., near the wall) of the co-current gas-solid downflow reactor.

[0011] A second object of the present invention is to provide a device for co-current gas-solid downflow fluidized catalytic cracking, where the catalyst concentration in the central region is higher and there is less accumulation near the wall in the mixing chamber, resulting in better contact with the vaporized feedstock.

[0012] A third object of the present invention is to provide a device for co-current gas-solid downflow fluidized catalytic cracking, where the arrangement of the injector is optimized according to the C / O ratio.

[0013] According to a first aspect, the above object and other advantages are achieved by a device for co-current gas-solid downflow fluidized catalytic cracking, which comprises, from top to bottom:

[0014] - a pipe adapted to convey a downward flow of catalyst particles;

[0015] - a mixing chamber connected to the pipe and adapted to be fed with a downward flow through the pipe, the mixing chamber including at least one first injector for injecting a hydrocarbon feedstock; and

[0016] - a co-current gas-solid downflow fluidized bed reactor connected to the mixing chamber and adapted to be fed with a mixture comprising catalyst particles and a hydrocarbon feedstock,

[0017] where at least one first injector has a predetermined angle α with respect to the horizontal plane, and the predetermined angle α satisfies the following two criteria:

[0018] - The vector of the resultant momentum calculated from the vector sum of the raw material momentum and the catalyst momentum has an angle λ of 70° to 80° relative to the horizontal plane; and

[0019] - The ratio of the vertical component of the raw material momentum to the catalyst momentum is from -0.2 to 0.1.

[0020] Advantageously, the device enables the homogenization of the concentration of catalyst particles along the fluidized bed reactor. Advantageously, the device enables the improvement of the contact between the catalyst and the vaporized raw material. Advantageously, the device enables the optimization of the arrangement and orientation of the injector according to the expected operating conditions.

[0021] According to one or more embodiments, the mixing chamber includes 2 to 12 first injectors, preferably 3 to 8 first injectors.

[0022] According to one or more embodiments, the vector of the resultant momentum has an angle λ of 72° to 77° relative to the horizontal plane; and / or the ratio of the vertical component of the raw material momentum to the catalyst momentum is from -0.13 to 0.04.

[0023] According to one or more embodiments, the first injectors are arranged countercurrent to the downward flow at an angle α of 15° to 45° relative to the horizontal plane.

[0024] According to one or more embodiments, the orientation of at least one first injector is offset from the diameter of the mixing chamber by an angle θ greater than 0° and less than or equal to 45°, and preferably 10° to 20°.

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

[0026] According to one or more embodiments, the mixing chamber includes at least one second injector for injecting a diluent.

[0027] According to one or more embodiments, the second injector has an angle β of 0° to 80°, and preferably 10° to 45°, relative to the horizontal plane.

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

[0029] According to one or more embodiments, the radial position of the second injector is located in the spaced-apart space between the 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 at an angle δ relative to the radial position of the adjacent first injector, and the angle δ is substantially equal to half of the separation angle γ between two adjacent first injectors.

[0031] According to one or more embodiments, the orientation of at least one second injector is off-axis with respect to the diameter of the mixing chamber by more than 0° and less than or equal to 45°, and preferably an angle σ of 10° to 20°.

[0032] According to one or more embodiments, at least a portion of the mixing chamber includes a central plug that is disposed substantially along the central / vertical axis of the mixing chamber and defines an annular orifice in the mixing chamber through which catalyst particles are discharged and / or flow into the mixing chamber.

[0033] According to a second aspect, the above object and other advantages are achieved by a method for cocurrent gas-solid downflow fluid catalytic cracking, the method comprising the steps of:

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

[0035] - feeding a downward flow through the (vertical) pipe to a mixing chamber that includes at least one first injector for injecting a hydrocarbon feedstock;

[0036] - feeding a mixture comprising catalyst particles and a hydrocarbon feedstock through the mixing chamber to a cocurrent gas-solid downflow fluidized bed reactor; and

[0037] - in the cocurrent gas-solid downflow fluidized bed reactor, at least partially cracking the hydrocarbon feedstock in the presence of the catalyst particles to produce an effluent comprising at least partially coked catalyst and gaseous cracking products,

[0038] wherein at least one first injector has a predetermined angle α with respect to the horizontal plane, and the predetermined angle α satisfies the following two criteria:

[0039] - the resultant momentum vector calculated from the vector sum of the feedstock momentum and the catalyst (vertical and downward) momentum has an angle λ of 70° to 80° with respect to the horizontal plane; and

[0040] - the ratio of the vertical component of the feedstock momentum to the catalyst (vertical and downward) momentum is from -0.2 to 0.1. According to one or more embodiments, the method includes at least one of the following operating conditions:

[0041] - the catalyst particles comprise a matrix made of clay, silica or silica-alumina, an optional binder, an optional dopant and / or zeolite, for example comprising 15 wt% to 70 wt% of zeolite, preferably zeolite Y and / or zeolite ZSM-5, very preferably zeolite ZSM-5, which is optionally doped, based on the weight of the catalyst;

[0042] - the particle density of the catalyst particles is 1000 kg / m 3 to 2000 kg / m 3, preferably 1250 kg / m 3 to 1750 kg / m 3 ;

[0043] - The hydrocarbon feedstock is a hydrocarbon feedstock with an initial boiling point higher than or equal to 340 °C or a hydrocarbon feedstock with a final boiling point lower than or equal to 450 °C;

[0044] - The downward flow of catalyst particles in the (vertical) pipe upstream of the mixing chamber is in a dense-phase fluidization state, preferably with a mass flow rate greater than 200 kg / m 2 s;

[0045] - The reactor outlet temperature is from 520 °C to 750 °C, and preferably lower than 650 °C;

[0046] - The absolute total pressure is from 0.1 MPa to 0.5 MPa;

[0047] - The mass ratio C / O of the catalyst to the hydrocarbon feedstock is from 5 (kg / h) / (kg / h) to 35 (kg / h) / (kg / h), and preferably from 15 (kg / h) / (kg / h) to 30 (kg / h) / (kg / h);

[0048] - The contact time tc between the hydrocarbon feedstock and the catalyst is less than 10 seconds, preferably from 0.5 seconds to 4 seconds;

[0049] - The mass flow rate of the catalyst particles is from 50 to 850 kg / (m 2 s), preferably from 400 to 750 kg / (m 2 s);

[0050] - The superficial gas velocity is from 2 m / s to 26 m / s, preferably from 6 m / s to 16 m / s;

[0051] - Diluent is injected through the first injector and / or at least one second injector, and the amount thereof accounts for 0% or 0.1 wt% to 40 wt% relative to the mass of the hydrocarbon feedstock, preferably 1 wt% to 35 wt%, and preferably 1 wt% to 30 wt%.

[0052] Other features and advantages of the invention in the above aspects will become apparent by reading the following description of non-limiting exemplary embodiments and referring to the accompanying drawings described below.

[0053] List of Drawings

[0054] Figure 1 A cross-sectional view of an FCC unit including an injector for equalizing the catalyst flow according to one or more embodiments of the present invention.

[0055] Figure 2A diagram and a cross-sectional view showing the fluid flow in the mixing chamber of an FCC unit according to one or more embodiments of the present invention.

[0056] Figure 3 A schematic top view of the mixing chamber of an FCC unit according to one or more embodiments of the present invention is shown.

[0057] Figure 4 A 3D view of an FCC unit according to one or more embodiments of the present invention is shown.

[0058] Figure 5 A 3D view showing the layout A of a reference FCC unit and the layout B of an FCC unit according to one or more embodiments of the present invention is shown.

[0059] Figure 6 Respectively shown Figure 5 in the reference FCC unit and Figure 5 3D views of layouts A and B of the catalyst volume fraction averaged over time in the FCC unit according to the present invention.

[0060] Figure 7 Respectively shown Figure 5 the reference FCC unit and Figure 5 radial distributions A and B of the solid fraction and the solid mass flow rate at 2.8 meters below the injector of the FCC unit of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0062] Embodiments according to the above aspects will now be described in detail. The following detailed description discloses many specific details in order to provide a deeper understanding of the apparatus and method according to the present invention. However, it will be apparent to those skilled in the art that the apparatus can be implemented without these specific details. In other cases, well-known features have not been described in detail to avoid unnecessarily complicating the description.

[0063] In this specification, the term "comprising" is synonymous with "having", "containing", and "including" (having the same meaning), and is inclusive or open-ended and does not exclude other elements not mentioned. It should be understood that the term "comprising" includes the exclusive and closed term "consisting of". Further, in this specification, the term "substantially" or "essentially" or "about" corresponds to an approximation of ±10%, preferably ±5%, and very preferably ±1%.

[0064] The present invention relates to an apparatus and method for fluid catalytic cracking (FCC) for the chemical conversion of petroleum products, such as for high severity fluid catalytic cracking (HS-FCC).

[0065] The FCC unit generally processes (so-called heavy) hydrocarbon fractions obtained from a vacuum distillation unit, such as vacuum gas oil or vacuum residue, alone or as a mixture, or atmospheric residue. The FCC unit can also process (so-called light) hydrocarbon fractions, such as gasoline fractions or gas oil fractions, alone or as a mixture. Mixtures of light and heavy fractions can also be processed, or the whole crude oil can be processed. In order to increase the yields of propylene and ethylene by using highly severe reaction conditions (high temperature, extremely short contact time, high C / O ratio between catalyst flow rate C and feedstock flow rate O), catalytic cracking units and methods generally employ a co-current gas-solid downflow fluidized bed reactor ("downflow bed" or "downflow reactor"), hereinafter referred to as the downflow reactor.

[0066] However, the downward gas-solid flow may face many technical challenges, including achieving uniform flow and mixing in the established flow section of the downflow reactor.

[0067] To overcome these drawbacks, it has been determined to improve the downflow reactor technology described in patent FR 2 753 453 B1 to address the above challenges, through a specific arrangement of the hydrocarbon feed injector and an optional diluent injector, to improve the contact between the catalyst and the hydrocarbon in the mixing chamber.

[0068] The device according to the invention

[0069] Reference Figure 1 , the device according to one or more embodiments of the invention comprises, from top to bottom:

[0070] -(substantially vertical) pipe 1;

[0071] -mixing chamber 2; and

[0072] -(substantially vertical) downflow reactor 3.

[0073] Pipe 1 is adapted to feed solid catalyst (particles) to the mixing chamber 2. Pipe 1 mainly conveys solids, as well as the fluidizing gas entrained by the downward-flowing solids. Pipe 1 has a riser-like flow well-known to those skilled in the art.

[0074] Mixing chamber 2 is connected to pipe 1 and is adapted to feed a mixture comprising catalyst particles, hydrocarbon feedstock and optionally diluent to the downflow reactor 3.

[0075] Downflow reactor 3 is connected to mixing chamber 2 and is adapted to at least partially crack the hydrocarbon feedstock in the presence of catalyst particles to produce an effluent comprising at least partially coked catalyst and gaseous cracking products and optionally un-converted vaporized feedstock.

[0076] Specifically, reference Figure 1, Pipe 1 feeds a downward flow 4 of (hot) catalyst particles into mixing chamber 2, which includes one or more first injectors 5 for injecting hydrocarbon feedstock 6. According to one or more embodiments, the (one or more) first injectors 5 are adapted to inject a diluent (such as steam) together with the feedstock. According to one or more embodiments, mixing chamber 2 includes one or more second injectors 7 for injecting diluent 8. In mixing chamber 2, the downward flow 4 contacts the hydrocarbon feedstock 6 atomized by the (one or more) first injectors 5 and optionally contacts the diluent 8 introduced, for example, by the (one or more) second injectors 7.

[0077] Advantageously, the injection of diluent 8 enables the reduction of the partial pressure of the hydrocarbon feedstock and the reduction of side reactions. Advantageously, the injection of diluent 8 enables the improvement of the atomization of hydrocarbon feedstock 6. According to one or more embodiments, diluent 8 is selected from steam, nitrogen, CO 2 , light hydrocarbons (such as C1-C5 compounds), and flue gas. According to one or more embodiments, diluent 8 comprises steam or consists of steam.

[0078] According to one or more embodiments, pipe 1 has a geometry with a constant cross-section, such as cylindrical, square, rectangular, or hexagonal, or has a geometry with a variable cross-section, such as a truncated cone or a frustum of a cone, or a combination of various geometries. According to one or more embodiments, pipe 1 is of a cylindrical shape and optionally has a variable diameter. According to one or more embodiments, pipe 1 is at least partially of a frustum-of-a-cone shape. According to one or more embodiments, pipe 1 includes (in the flow direction of the solid catalyst): a cylindrical section, the diameter of which is, for example, selected to obtain a solid flow rate of 100 to 800 kg / (m 2 s) and preferably 300 to 600 kg / (m 2 s); a frustum-of-a-cone (“narrowing”) section adjacent to mixing chamber 2, the diameter of which decreases, for example, in order to achieve a solid flow rate of 400 to 2000 kg / (m 2 s) and preferably 700 to 1500 kg / (m 2 s) without considering the internal components; and an optional second cylindrical section, the diameter of which is, for example, selected to obtain a solid flow rate of 400 to 2000 kg / (m 2 s) and preferably 700 to 1500 kg / (m 2 s) without considering the internal components.

[0079] According to one or more embodiments, the mixing chamber 2 has a geometric shape with a constant cross-section, such as cylindrical, square, rectangular or hexagonal, or a geometric shape with a variable cross-section, such as a frustum or a truncated cone, or a combination of various geometric shapes. The mixing chamber 2 may be provided with a central internal member, such as the central plug described below with reference to Figure 5 the central plug. According to one or more embodiments, the mixing chamber 2 is of a cylindrical shape and optionally has a variable diameter. According to one or more embodiments, the mixing chamber 2 is at least partially of a truncated conical shape. According to one or more embodiments, the mixing chamber 2 includes an upper cross-sectional boundary S1 connecting the mixing chamber 2 to the duct 1 and a lower cross-sectional boundary S2 connecting the mixing chamber 2 to the downflow reactor 3, and the ratio S1 / S2 is less than 0.9, and preferably less than 0.7. According to one or more embodiments, the ratio S1 / S2 is from 0.4 to 0.9, preferably from 0.5 to 0.7.

[0080] According to one or more embodiments, the mixing chamber 2 includes 2 to 12 first injectors 5, preferably 3 to 8 first injectors 5.

[0081] Reference Figure 1 and Figure 2 the applicant has determined that the axial direction of the first injector 5 is a key factor for good dispersion of the catalyst. Specifically, according to the present invention, the first injector 5 has a predetermined angle α (alpha) with respect to the horizontal plane, and this predetermined angle α satisfies the following two criteria:

[0082] - The resultant momentum M 6 calculated from the vector sum of the raw material momentum (defined as mass (or mass flow rate) * velocity) M 4 and the catalyst momentum M tot has an angle λ (lambda) of 70° to 80°, and preferably 72° to 77°, with respect to the horizontal plane; and

[0083] - The ratio of the vertical component M 6v of the vector of the raw material momentum to the catalyst momentum M 4 is from -0.2 to 0.1, and preferably from -0.13 to 0.04.

[0084] Meeting these two criteria mainly causes the axial direction of the first injector 5 to be countercurrent to the downflow 4, for example, at an angle α of 0° to 80°, or slightly cocurrent with the downflow 4, for example, at an angle α of -20° to 0°. According to one or more embodiments, the first injector 5 is arranged at an angle α of 15° to 45° with respect to the horizontal plane and countercurrent to the downflow 4.

[0085] Furthermore, reference Figure 3, to promote turbulence in the mixing chamber 2 and direct the raw materials towards areas with a higher catalyst concentration, the orientation of at least one first injector 5 (in the projection on the horizontal plane) can be offset from the diameter of the mixing chamber 2 by an angle θ (theta) greater than 0° and less than or equal to 45°, and preferably 10° to 20°. According to one or more embodiments, adjacent offset first injectors 5 have positive and negative θ angles respectively, especially to improve turbulence.

[0086] Reference Figure 4 , according to one or more embodiments, the first injectors 5 are arranged in one or more horizontal rows, i.e., perpendicular to the central / vertical axis Z of the pipe 1, the mixing chamber 2, and the downflow reactor 3. According to one or more embodiments, adjacent first injectors 5 in a row of first injectors 5 are arranged on the wall of the mixing chamber 2 at a separation angle γ (gamma), which is substantially equal to 360° divided by the number of first injectors 5 in that row.

[0087] According to one or more embodiments, the mixing chamber 2 includes 2 to 12 second injectors 7, preferably 3 to 8 second injectors 7.

[0088] Reference Figure 1 , the second injectors 7 have an angle β (beta) of 0° to 80° with respect to the horizontal plane, and preferably 10° to 45°.

[0089] Reference Figure 4 , according to one or more embodiments, the second injectors 7 are arranged in one or more horizontal rows (perpendicular to the central / vertical axis Z).

[0090] Reference Figure 4 , according to one or more embodiments, the second injectors 7 are arranged below the first injectors 5 (e.g., rows of first injectors 5). According to one or more embodiments, the second injectors 7 are arranged between two rows of first injectors 5.

[0091] Reference Figure 3 and Figure 4 , according to one or more embodiments, the radial position of the second injectors 7 is located within the 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 at an angle δ (delta) with respect to the radial position of the first injector 5 adjacent to the second injector 7 (in the projection on the horizontal plane), and this angle δ is substantially equal to half of the separation angle γ between two adjacent first injectors 5.

[0092] Reference Figure 3 and Figure 4, To promote turbulence in the mixing chamber 2 and direct the catalyst towards regions of higher raw material concentration, the orientation of the second injector 7 (in the projection on the horizontal plane) can be off-axis with respect to the diameter of the mixing chamber by more than 0° and less than or equal to 45°, and preferably an angle σ (sigma) of 10° to 20°. To make Figure 4 the top view clearer, one row of injectors 5 was removed.

[0093] Reference Figure 1 , The mixing chamber 2 feeds a mixture of hydrocarbon raw material 6, catalyst particles, and optionally diluent 8 to the downflow reactor 3. Advantageously, the hydrocarbon raw material 6 and the catalyst particles cause a cracking reaction, which is completed in the downflow reactor 3 having a height L (along the central / vertical axis Z) to produce a hydrocarbon effluent 9 containing cracked products, spent catalyst, and possibly a portion of the unreacted hydrocarbon raw material.

[0094] Reference Figure 5 , According to one or more embodiments, at least a portion of the mixing chamber 2 includes a central plug 10, which is arranged substantially along the central / vertical axis Z and defines an annular opening 11 in the mixing chamber 2 through which the catalyst particles are discharged and / or flow into the mixing chamber 2.

[0095] According to one or more embodiments, the vertical position of the first injector 5 and / or the second injector 7 is between the top and bottom ends of the central plug 10, i.e., the raw material 6 and optionally the diluent 8 are introduced into the annular opening 11 of the mixing chamber 2.

[0096] According to one or more embodiments, the downflow reactor 3 has a geometric shape with a constant cross-section, such as cylindrical, square, rectangular, or hexagonal, and is preferably cylindrical. According to one or more embodiments, the downflow reactor 3 is cylindrical in shape and optionally has a 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 2 m / s to 26 m / s, preferably 6 m / s to 16 m / s.

[0097] Catalyst

[0098] The catalyst is a solid catalyst (e.g., particles having a density, size, and shape selected for a fluidized bed). The density, size, and shape of the catalyst for a fluidized bed are known to those skilled in the art and will not be elaborated further. The catalyst can be any type of catalytic cracking catalyst.

[0099] According to one or more embodiments, the catalyst is an FCC catalyst, which contains a matrix made of, for example, what is commonly referred to as clay, silica or silica-alumina, an optional binder and / or zeolite, for example containing 15 wt% to 70 wt% of zeolite, preferably zeolite Y and / or zeolite ZSM-5, based on the weight of the catalyst. According to one or more embodiments, the catalyst includes zeolite ZSM-5. According to one or more embodiments, the particle density of the catalyst is 1000 kg / m 3 to 2000 kg / m 3 According to one or more embodiments, the particle density of the catalyst is 1250 kg / m 3 to 1750 kg / m 3 .

[0100] According to one or more embodiments, the catalyst contains at least one binder (e.g., 30 wt% to 85 wt%), the binder being selected from alumina, silica, silica-alumina, magnesia, titania, zirconia, clay and boron oxide, individually or in a mixture, and preferably selected from silica, silica-alumina and clay, individually or in a mixture.

[0101] According to one or more embodiments, the catalyst contains at least one doping element (e.g., 0 to 10 wt%), the doping element being selected from phosphorus, magnesium, sodium, potassium, calcium, iron, boron, manganese, lanthanum, cerium, titanium, tungsten, molybdenum, copper, zirconium and gallium, individually or in a mixture.

[0102] According to one or more embodiments, the catalyst includes an optionally doped zeolite such as ZSM-5 and / or consists of the same.

[0103] Feedstock

[0104] According to one or more embodiments, the hydrocarbon feedstock 6 is a (so-called heavy) hydrocarbon feedstock, which is characterized by an initial boiling point of at least 340 °C, or even higher than 340 °C, typically higher than 380 °C, such as a heavy hydrocarbon fraction, such as obtained from a vacuum distillation unit, such as vacuum gas oil (VGO) / vacuum distillate or vacuum residue, atmospheric residue, vacuum gas oil obtained from a conversion unit, such as coker gas oil (heavy coker gas oil (HCGO)) or a heavy hydrocarbon fraction obtained from a ebullated bed or entrained flow hydroconversion unit (e.g., H-Oil, LC-Fining, EST, VCC or Uniflex process), recycle streams from a hydrocracking step, alone or as a mixture.

[0105] According to one or more embodiments, the hydrocarbon feedstock 6 is a so-called light feedstock, characterized by an end boiling point lower than or equal to 450 °C, typically lower than 400 °C, such as a gasoline fraction or a gas oil fraction, for example obtained from an atmospheric distillation unit, or from a conversion unit, such as gasoline or gas oil from a hydrocracking unit, or gasoline or gas oil from a coking unit, or gasoline or gas oil from a ebullated bed or entrained flow hydroconversion unit (such as the H-Oil, LC-Fining, EST, VCC or Uniflex processes), or gasoline or gas oil obtained from an FCC unit, or a recycle stream from a related FCC unit, alone or as a mixture. According to one or more embodiments, it is also possible to process a mixture of light and heavy hydrocarbon fractions or whole crude oil.

[0106] Once in contact with the downward flow 4 of hot catalyst particles, the atomized hydrocarbon feedstock 6 vaporizes and undergoes an endothermic cracking reaction along the downflow reactor 3, thereby reducing the temperature and producing:

[0107] - Upgradable products (e.g., C1-C4 gases containing olefins; gasoline fractions containing aromatics);

[0108] - Optionally, a light gas oil fraction (light cycle oil (LCO));

[0109] - Optionally, a heavy gas oil fraction (heavy cycle oil (HCO));

[0110] - Optionally, oil in the form of slurry; and

[0111] - Optionally, solid residues (residue) (coke) adsorbed on the catalyst.

[0112] The method according to the invention

[0113] The method according to the invention comprises a catalytic cracking stage for catalytically cracking the hydrocarbon feedstock 6 (fed through the first injector 5) by contacting it in the mixing chamber 2 and then in the downflow reactor 3 with the downward flow 4 of hot catalyst particles (fed through the pipe 1) and optionally a diluent 8 (fed through the second injector 7) to produce light olefins (and in particular ethylene and propylene), aromatics (and in particular benzene, toluene and xylene) and gasoline (and optionally LCO, HCO and slurry).

[0114] According to one or more embodiments, the downward flow 4 of catalyst particles in the pipe 1 upstream of the mixing chamber 2 is in a dense phase fluidized state, preferably having a mass flow rate greater than 200 kg / m 2 s to preferably achieve a state with descending bubbles, for example.

[0115] In the present patent application, the term "dense phase fluidized bed" refers to a gas-solid fluidized bed operating in a homogeneous state, a bubbling state, or a turbulent state.

[0116] In the present patent application, the term "homogeneous fluidized bed" refers to a gas-solid fluidized bed in which the 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, shape, etc. of the particles). The solid volume fraction is between a value close to 0.45 and the maximum solid volume fraction corresponding to a non-fluidized fixed bed (generally close to 0.6).

[0117] In the present patent application, the term "bubbling fluidized bed" refers to a gas-solid fluidized bed in which the gas velocity is between the minimum bubbling velocity and the velocity at which transition to the turbulent state occurs. These velocities depend on the properties of the solid catalyst (density, size, shape, etc. of the particles). The volume fraction of the solid is between a value close to 0.35 and a value close to 0.45.

[0118] In the present patent application, the term "turbulent fluidized bed" refers to a gas-solid fluidized bed in which the gas velocity is between the velocity at which transition to the turbulent state occurs and the transport velocity. The solid volume fraction is between a value close to 0.25 and a value close to 0.35.

[0119] In the present patent application, the term "transport fluidized bed" refers to a gas-solid fluidized bed in which the gas velocity is greater than the transport velocity. The volume fraction of the solid is less than a value close to 0.25. In the present patent application, the term "transport velocity" corresponds to the velocity at which substantially all of the solid is entrained by the gas.

[0120] According to one or more embodiments, the injector 5 is adapted to atomize the hydrocarbon feedstock 6 (liquid) and penetrate the catalyst stream.

[0121] According to one or more embodiments, the operating conditions of the pipe 1 and / or the downflow reactor 3 are selected from the following conditions:

[0122] - The temperature (at the reactor outlet) is from 520 °C to 750 °C, and preferably less than 650 °C;

[0123] - The absolute total pressure is from 0.1 MPa to 0.5 MPa;

[0124] - The weight ratio C / O of the catalyst 4 to the hydrocarbon feedstock 6 is from 5 (kg / h) / (kg / h) to 35 (kg / h) / (kg / h), and preferably from 15 (kg / h) / (kg / h) to 30 (kg / h) / (kg / h);

[0125] - The contact time t of the hydrocarbon feedstock 6 with the catalyst c is less than 10 seconds, preferably from 0.5 second to 4 seconds;

[0126] - The mass flow rate of the catalyst particles is 50 to 850 kg / (m 2 s), preferably 400 to 750 kg / (m 2 s); and

[0127] - The superficial gas velocity is 2 m / s to 26 m / s, preferably 6 m / s to 16 m / s.

[0128] In this specification, the contact time t c is defined as the product of the solid volume fraction ε s and the bed height H s (e.g., the reactor height L), divided by the superficial gas velocity sgv, and integrated along the bed height, as defined by the following mathematical formula Math 1.

[0129] Math 1

[0130]

[0131] According to one or more embodiments, a certain amount of diluent 8 (e.g., nitrogen and / or steam) is added to the feedstock to reduce the partial pressure of the hydrocarbons in the feedstock, and the diluent is introduced in an amount of 0% or 0.1% to 40% by weight, preferably 1% to 35% by weight, and preferably 1% to 30% by weight, based on the mass of the hydrocarbon feedstock 6.

[0132] According to one or more embodiments, at the end of the catalytic cracking step in the downflow reactor 3, the gaseous products, the catalyst, and optionally the unreacted vaporized feedstock are separated in a gas / solid separator (not shown) containing a dense-phase fluidized bed, where the cracking reaction can continue.

[0133] According to one or more embodiments, the operating conditions of the separator are selected from the following conditions:

[0134] - The temperature (at the reactor outlet) is 500 °C to 750 °C, preferably 550 °C to 700 °C, and even more preferably 580 °C to 685 °C;

[0135] - The absolute total pressure is 0.1 MPa to 0.5 MPa, and preferably 0.1 MPa to 0.4 MPa, and preferably 0.1 MPa to 0.3 MPa;

[0136] - The weight ratio C / O of the catalyst to the feedstock (unreacted vaporized feedstock and gaseous products) is 5 (kg / h) / (kg / h) to 40 (kg / h) / (kg / h);

[0137] - The contact time t c between the feedstock and the catalyst is 500 milliseconds (ms) to 10 seconds; and

[0138] - The partial pressure of hydrocarbons in the feedstock (PPH feedstock) is from 0.01 MPa to 0.3 MPa, preferably from 0.02 MPa to 0.2 MPa, and more preferably from 0.05 MPa to 0.15 MPa.

[0139] According to one or more embodiments, at the outlet of the separator, the coked catalyst is sent to an optional stripping column (not shown) to strip the hydrocarbons still adsorbed on the catalyst surface with a second diluent.

[0140] According to one or more embodiments, the operating conditions of the stripping column are selected from the following conditions:

[0141] - Residence time of the catalyst in the stripping column: 10 seconds to 180 seconds, preferably 30 seconds to 120 seconds;

[0142] - The superficial gas velocity is between the minimum fluidization velocity and the velocity at which transition to the turbulent state occurs, for example, from 0.01 m / s to 0.5 m / s, preferably from 0.15 m / s to 0.4 m / s;

[0143] - The solid flow rate is 25 kg / m 2 s to 200 kg / m 2 s, preferably 50 kg / m 2 s to 150 kg / m 2 s, and more preferably 50 kg / m 2 s to 100 kg / m 2 s;

[0144] - The temperature is from 500 °C to 750 °C, preferably from 550 °C to 650 °C;

[0145] - The absolute total pressure is from 0.1 MPa to 0.5 MPa, and preferably from 0.1 MPa to 0.4 MPa, and more preferably from 0.1 MPa to 0.3 MPa;

[0146] - The solid volume fraction is from 0.25 to 0.6, preferably from 0.4 to 0.6.

[0147] According to one or more embodiments, at the outlet of the separator or the stripping column, the coked solid is transported to a regenerator (not shown), where the air supply burns the coke on the catalyst to produce a hot regenerated catalyst and combustion gas, and the hot regenerated catalyst can feed the hot catalyst particles in the downflow 4.

[0148] According to one or more embodiments, the operating conditions of the regenerator are selected from the following conditions:

[0149] - The superficial gas velocity is from 0.1 m / s to 2 m / s, preferably from 0.2 m / s to 1.5 m / s;

[0150] - The residence time of the catalyst is from 30 seconds to 20 minutes, preferably from 1 minute to 10 minutes;

[0151] - The temperature is from 500 °C to 840 °C, preferably from 650 °C to 750 °C. Examples

[0152] Reference Figure 5 , to study the hydrodynamics, the flow in a reference device A operated under non-reacting conditions and in a device B according to the invention was compared.

[0153] The reference device A comprises:

[0154] - A pipe 1, which consists of a cylindrical part, a narrowing cone and a cylindrical part;

[0155] - A frustoconical mixing chamber 2 (S1 / S2 less than 1), which comprises a central plug 10 defining an annular orifice 11;

[0156] - A cylindrical downflow reactor 3, which has a length of 4.07 m and an inner diameter of 0.42 m;

[0157] - Four first injectors 5 for injecting a hydrocarbon feedstock 6, which are positioned at a downward angle of 45° relative to the horizontal direction in co-current with the downward flow 4 of catalyst particles, which generates a resultant momentum M tot of a vector at an angle λ. The vertical component M 6v of the feedstock momentum and the catalyst momentum M 4 have a ratio of 0.23, which exceeds the recommended range; and

[0158] - Four second injectors 7 for injecting a diluent 8 (steam), which are positioned at a downward angle of 45° relative to the horizontal direction in co-current with the downward flow 4 of catalyst particles.

[0159] The device B according to the invention comprises:

[0160] - A pipe 1, which consists of a cylindrical part, a narrowing cone and a cylindrical part;

[0161] - A frustoconical mixing chamber 2 (S1 / S2 less than 1), which comprises a central plug 10 defining an annular orifice 11;

[0162] - A cylindrical downflow reactor 3, which has a length of 4.07 m and an inner diameter of 0.42 m;

[0163] - Four first injectors 5 for injecting a hydrocarbon feedstock 6, which are positioned at an upward angle α of 30° relative to the horizontal direction in counter-current with the downward flow 3 of catalyst particles, which generates a resultant momentum M totThe angle λ of the vector. The vertical component M of the raw material momentum 6v and the catalyst momentum M 4 The ratio is -0.16; and

[0164] - Four second injectors 7 for injecting a diluent 8 (steam), which are positioned at an upward angle β of 30° relative to the horizontal direction and countercurrent to the downward flow 3 of the catalyst particles.

[0165] Used in CFD The tool simulates the configurations of the reference device A and the device B according to the present invention under the following operating conditions:

[0166] - The catalyst flow rate is 607 kg / m 2 s;

[0167] - The catalyst has a diameter d of 73 μm 50 and a particle density of 1418 kg / m 3 (i.e., Group A of Geldart classification);

[0168] - An air flow rate of 1.85 kg / s shows a ratio of the first injector 5 to the second injector 7 of 70 / 30;

[0169] - The first injector 5 is located 0.2 m above the second injector 7;

[0170] - The rotation angle δ between the first injector 5 and the second injector 7 is 45°;

[0171] - The gas velocity at the injector outlet of the first injector 5 is 90 m / s, while the gas velocity at the injector outlet of the second injector 7 is 76 m / s;

[0172] - The flow is under ambient non-reactive conditions;

[0173] - The central plug 10 is located at the center of the mixing chamber 2.

[0174] Figure 6 Shows the particle volume fractions (expressed as VFP) of the two configurations A and B of the reference device A and the device B according to the present invention at 13 cross-sections. The first two cross-sections are respectively located at the heights of the first injector 5 and the second injector 7, and the subsequent cross-sections are spaced 0.35 m apart.

[0175] Advantageously, compared with the reference device A, for the device B according to the present invention, the radial distribution of the solid is always more uniform throughout the downflow reactor 3. In addition, compared with the device B according to the present invention, a higher solid concentration near the wall can be noticed for the reference device A.

[0176] Figure 7 Respectively show Figure 5Radial distributions A and B of the particle volume fraction VFP and the particle mass flow rate (expressed as MFP) for the reference apparatus A and the apparatus B according to the present invention. The radial distributions A and B are generated in the x-direction (perpendicular to the center / vertical axis Z) at a height of 2.8 m below the first injector 5. It is notable that the apparatus B according to the present invention produces a more uniform radial distribution B with a better phase distribution. The coefficient of variation of the particle volume fraction VFP values on these radial distributions A and B is 40% for the reference apparatus A and 15% for the apparatus B according to the present invention. Similarly, the coefficient of variation of the particle mass flow rate MFP values on the distributions A and B is 59% for the reference apparatus A and 16% for the apparatus B according to the present invention, indicating that for the apparatus B according to the present invention, the catalyst has better dispersion across the cross-section.

Claims

1. A method for concurrent gas-solid downflow fluid catalytic cracking, which comprises the following steps: - Conveying a downward flow (4) of catalyst particles in a vertical pipe (1); - Feeding the downward flow (4) through the vertical pipe (1) into a mixing chamber (2), the mixing chamber (2) comprising at least one first injector (5) for injecting a hydrocarbon feedstock (6); - Feeding a mixture comprising catalyst particles and a hydrocarbon feedstock through the mixing chamber (2) into a concurrent gas-solid downflow fluidized bed reactor (3); and - In the concurrent gas-solid downflow fluidized bed reactor (3), at least partially cracking the hydrocarbon feedstock (6) in the presence of the catalyst particles to produce an effluent (9) comprising at least partially coked catalyst and gaseous cracking products; wherein at least one first injector (5) has a predetermined angle α with respect to the horizontal plane, and the predetermined angle α satisfies the following two criteria: - The resultant momentum (M 6 ) calculated from the vector sum of the raw material momentum (M 4 ) and the catalyst momentum (M tot ) that is perpendicular and downward has an angle λ of 70° to 80° with respect to the horizontal plane; and - The ratio of the vertical component of the raw material momentum (M 6v ) to the vertically downward momentum of the catalyst (M 4 ) is from -0.2 to 0.

1.

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

3. The method according to claim 1 or claim 2, wherein the vector of the synthetic momentum (M tot ) has an angle λ of 72° to 77° relative to the horizontal plane; and / or the ratio of the vertical component of the raw material momentum (M 6v ) to the vertically downward momentum of the catalyst (M 4 ) is from -0.13 to 0.

04.

4. The method according to any one of the preceding claims, wherein the first injector (5) is arranged at an angle α of 15° to 45° with respect to the horizontal plane and countercurrent to the downward flow (4).

5. The method according to any one of the preceding claims, wherein the orientation of at least one first injector (5) is offset from the diameter of the mixing chamber (2) by an angle θ greater than 0° and less than or equal to 45°, and preferably 10° to 20°.

6. The method according to any one of the preceding claims, wherein the first injector (5) is arranged in one or more horizontal rows.

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

8. The method according to claim 7, wherein the second injector (7) is arranged countercurrent to the downward flow (4) and has an angle β of 0° to 80°, and preferably 10° to 45° with respect to the horizontal plane.

9. The method according to claim 7 or 8, wherein the second injector (7) is arranged in one or more horizontal rows.

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

11. The method according to any one of claims 7 to 10, wherein the radial position of at least one second injector (7) is arranged at an angle δ with respect to the radial position of an adjacent first injector (5), and the angle δ is substantially equal to half of the separation angle γ between two adjacent first injectors (5).

12. The method according to any one of claims 7 to 11, wherein the orientation of at least one second injector (5) is offset from the diameter of the mixing chamber (2) by an angle σ greater than 0° and less than or equal to 45°, and preferably 10° to 20°.

13. The method according to any one of the preceding claims, wherein at least a part of the mixing chamber (2) comprises a central plug (10), which is arranged substantially along the central / vertical axis (Z) of the mixing chamber (2) and defines an annular orifice (11) in the mixing chamber (2), through which the catalyst particles are discharged and / or flow into the mixing chamber (2).

14. The 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, an optional binder, an optional dopant and / or zeolite, for example comprising 15% to 70% by weight of zeolite, preferably zeolite Y and / or zeolite ZSM-5, very preferably zeolite ZSM-5, relative to the weight of the catalyst, which is optionally doped; - The particle density of the catalyst particles is 1000 kg / m 3 to 2000 kg / m 3 , preferably 1250 kg / m 3 to 1750 kg / m 3 ; - The hydrocarbon feedstock (6) is a hydrocarbon feedstock having an initial boiling point higher than or equal to 340 °C or a final boiling point lower 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 a dense-phase fluidized state, preferably with a mass flow rate greater than 200 kg / m 2 s; - The reactor outlet temperature is from 520 °C to 750 °C, and preferably lower than 650 °C; - The absolute total pressure is from 0.1 MPa to 0.5 MPa; - The mass ratio C / O of the catalyst (4) to the hydrocarbon feedstock (6) is from 5 (kg / h) / (kg / h) to 35 (kg / h) / (kg / h), and preferably from 15 (kg / h) / (kg / h) to 30 (kg / h) / (kg / h); - The contact time tc between the hydrocarbon feedstock (6) and the catalyst is less than 10 seconds, preferably from 0.5 second to 4 seconds; - The mass flow rate of the catalyst particles is 50 to 850 kg / (m 2 s), preferably 400 to 750 kg / (m 2 s); - The superficial gas velocity is from 2 m / s to 26 m / s, preferably from 6 m / s to 16 m / s; - Diluent (8) is injected through the first injector (5) and / or at least one second injector (7) in an amount of 0% or from 0.1% to 40% by weight, preferably from 1% to 35% by weight, and preferably from 1% to 30% by weight, relative to the mass of the hydrocarbon feedstock (6).

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