Gas-solid parallel flow down-flow fluidized bed reactor with uniform flow

Abstract

Apparatus and method for co-current gas-solid downflow fluid catalytic cracking, comprising / using: a conduit (1) adapted to convey a downflow (4) of catalyst particles; a mixing chamber (2) connected to the conduit (1) and adapted to be fed with a downstream flow through the conduit, the mixing chamber comprising an inner wall, at least one first injector (5) for injecting a hydrocarbon feedstock (6); a co-current gas-solid down-flow fluidized bed reactor (3) connected to the mixing chamber and adapted to be fed through the mixing chamber with a mixture comprising catalyst particles and a hydrocarbon feedstock, the co-current gas-solid down-flow fluidized bed reactor comprising an inner wall, wherein the mixing chamber and / or the inner wall of the co-current gas-solid down-flow fluidized bed reactor comprises one or more obstacles (9).

Description

Technical Field

[0001] The present invention relates to the fields of oil refining and petrochemicals and to a process and an apparatus for chemically converting 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 particularly ethylene and propylene, and aromatics (e.g. BTX), and more particularly paraxylene. Prior art

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

[0003] Ethylene, propylene, butylene, 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 (e.g. naphtha, kerosene or gas oil). These compounds are also obtained by fluid catalytic cracking (FCC) of hydrocarbons, for example vacuum distillates (VD, or vacuum gas oil VGO) and / or hydrocarbons and / or naphtha, gas oil and whole crude oil distillation (vacuum or atmospheric pressure) residues.

[0004] The high severity catalytic cracking (HS-FCC) process aims to increase the yield of propylene and ethylene through high temperature reaction conditions, very short contact time (eg, ~1 second) and a high catalyst mass flow C to feedstock mass flow O ratio (C / O).

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

[0006] To overcome these shortcomings, the HS-FCC process uses a downflow reactor in which the catalyst and feedstock are set to move under gravity, and the flow is close to plug flow. The downward gas-solid flow in the reactor avoids backmixing and over-cracking of the products, while the use of a high C / O ratio ensures the dominance of the catalytic reaction. High temperatures promote the formation of reaction intermediates such as light olefins, while controlled and short contact times avoid side reactions that lead to the consumption of such intermediates.

[0007] However, downflow gas-solid flow presents a number of significant technical challenges, one of which corresponds to the flow and mixing within the established flow cross-section of the reactor. Specifically, catalyst flow in downflow reactors, especially at high solid mass flow rates (e.g., 400-800 kg / m2 s), it is characterized by a flat solid concentration distribution in the central region, while the particle concentration and flow rate are higher in the annular region near the wall. This segregation is due to the low-speed condition (no slip condition) of the gas at the wall, which produces weak resistance to the particles and causes aggregation between the particles. This phenomenon is well described in the literature (Zhu et al., The Canadian Journal of Chemical Engineering, Vol. 73 (1995), pp. 662-677; Sun et al., Powder Technology, Vol. 370 (2020), pp. 184-196). However, this segregation results in a lower catalyst concentration in the center of the reactor, thereby reducing the overall performance obtained at the reaction rate and the reactor outlet.

[0008] Patent FR 2 753 453 B1 describes a downflow cracking reactor comprising a zone for contacting hydrocarbons with a catalyst, the zone consisting of a mixing chamber of maximum cross-section S2 placed in communication with means for supplying regenerated catalyst through an upper opening defining a catalyst flow area S1, and a reaction zone of maximum cross-section S4 placed in communication with the mixing chamber through a middle opening having a cross-section S3, in which reactor the ratios S2 / S1 and S2 / S3 are between 1.5 and 8.

[0009] Patents US 10,889,768 B2 and US 10,767,117 B2 describe systems and processes for producing petrochemical products (such as ethylene and other olefins) from hydrocarbon feedstocks (such as crude oil) in a high severity fluid catalytic cracking (HS-FCC) unit.

[0010] Patent application US2022 / 0016589 A1 describes a downflow reactor comprising annular distribution and mixing baffles. SUMMARY OF THE INVENTION

[0012] Against the above background, a first object of the present invention is to overcome the problems of the prior art and to provide an apparatus for co-current gas-solid downflow fluid catalytic cracking with a uniform catalyst flow, i.e. in which the solids concentration in the cross section of the reactor is substantially uniform. In particular, the apparatus according to the invention makes it possible to obtain a uniform catalyst concentration between the central region and the annular region (i.e. near the wall) of a co-current gas-solid downflow reactor.

[0013] A second object of the present invention is to provide an apparatus for co-current gas-solid downflow catalytic cracking wherein the solids concentration in the feed injection region of the mixing chamber is increased.

[0014] According to a first aspect, the above objects and other advantages are achieved by a device for co-current gas-solid downflow fluid catalytic cracking, the device comprising from top to bottom:

[0015] - a conduit suitable for conveying a downward flow of catalyst particles;

[0016] - a mixing chamber connected to the pipeline and adapted to be fed with a downward flow through the pipeline, the mixing chamber comprising an inner wall and at least one first injector for injecting the hydrocarbon feedstock;

[0017] a co-current gas-solid downflow fluidized bed reactor connected to a mixing chamber and adapted to be fed with a mixture comprising catalyst particles and a hydrocarbon feedstock through the mixing chamber, the co-current gas-solid downflow fluidized bed reactor comprising an inner wall;

[0018] The inner wall of the mixing chamber and / or the co-current gas-solid downflow fluidized bed reactor comprises one or more discontinuous obstacles.

[0019] Advantageously, the plurality of obstacles are adapted to homogenize the concentration of the catalyst particles. Advantageously, the obstacles are adapted to deflect (the trajectory of) the catalyst particles towards the interior of the mixing chamber and / or the co-current gas-solid downflow fluidized bed reactor, and / or towards the feedstock injection zone (i.e., near the first injector for injecting the hydrocarbon feedstock).

[0020] According to one or more embodiments, the obstacles are adapted to distribute the catalyst particles substantially toward the interior of the mixing chamber and / or the co-current gas-solid downflow fluidized bed reactor.

[0021] According to one or more embodiments, the obstacle comprises an inclined upper surface that descends inwardly (ie, toward the center of the reactor).

[0022] According to one or more embodiments, the barrier is adapted to prevent accumulation of catalyst particles on the barrier.

[0023] According to one or more embodiments, the obstacles are adapted to distribute the catalyst particles along the walls of the mixing chamber.

[0024] According to one or more embodiments, the obstacle comprises an upper surface that is inclined and descends laterally.

[0025] According to one or more embodiments, the obstacles are prismatic, cylindrical, pyramidal, conical and / or frustoconical in shape.

[0026] According to one or more embodiments, an obstacle is arranged in the mixing chamber upstream of the at least one first injector.

[0027] According to one or more embodiments, the obstacle is positioned in the downflow reactor at an axial distance Hi of 0*L to 0.9*L from the mixing chamber, L being the length of the co-current gas-solid downflow fluidized bed reactor.

[0028] According to one or more embodiments, the device comprises at least one obstacle row arranged at a predetermined height of the inner wall of the mixing chamber and / or the downflow reactor.

[0029] According to one or more embodiments, the row of obstacles occupies 15% to 80% of the circumference of the inner wall of the mixing chamber and / or downflow reactor.

[0030] According to one or more embodiments, the obstacle row reduces the flow area of ​​the inner wall of the mixing chamber and / or downflow reactor by 1% to 35%, and preferably by 5% to 20%.

[0031] According to one or more embodiments, the row of obstacles in the mixing chamber comprises from 2 to 24 obstacles, and / or the row of obstacles in the downflow reactor comprises from 2 to 24 obstacles.

[0032] According to one or more embodiments, the radial position of an obstacle in one obstacle row is located in a spacing space between the radial positions of two adjacent obstacles in an adjacent obstacle row.

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

[0034] - a downward flow of catalyst particles transported in a conduit;

[0035] - feeding a mixing chamber through a conduit downflow, the mixing chamber comprising an inner wall and at least one first injector for injecting a hydrocarbon feedstock;

[0036] - feeding a mixture comprising catalyst particles and a hydrocarbon feedstock to a co-current gas-solid downflow fluidized bed reactor through a mixing chamber, the co-current gas-solid downflow fluidized bed reactor comprising an inner wall; and - in the co-current 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,

[0037] The inner wall of the mixing chamber and / or the co-current gas-solid downflow fluidized bed reactor comprises a plurality of obstacles.

[0038] Other features and advantages of the invention of the above-described aspects will become apparent upon reading the following description of non-limiting exemplary embodiments and with reference to the accompanying drawings described below.

[0039] List of Figures

[0040] Figure 1 An FCC unit according to one or more embodiments of the present invention is shown that includes obstacles for homogenizing the catalyst flow.

[0041] Figure 2 A 3D view of an FCC unit including multiple rows of obstacles for homogenizing catalyst flow is shown in accordance with one or more embodiments of the present invention.

[0042] Figure 3 A 3D view of layout A of a reference FCC unit and a 3D view of layout B of an FCC unit including three obstacle rows according to one or more embodiments of the present invention are shown.

[0043] Figure 4 They are shown respectively Figure 3 The reference FCC device and Figure 3 3D views of layout A and layout B of the catalyst volume fraction averaged over time in an FCC unit according to the present invention.

[0044] Figure 5 They are shown respectively Figure 3 Radial distribution of solid fraction and solid mass flow rate A at 2.8 m below the injector of the reference FCC unit and Figure 3 Radial distribution B of the solid fraction and solid mass flow rate at 2.8 meters below the injector of the FCC device of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0046] Embodiments according to the above aspects will now be described in detail. The following detailed description discloses many specific details in order to more deeply understand the device and method according to the present invention. However, it will be apparent to those skilled in the art that the device can be implemented without these specific details. In other cases, well-known features are not described in detail to avoid unnecessarily complicating the description.

[0047] In the present specification, the term "comprising" is synonymous with "having", "including" and "containing", 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..." In addition, in the present specification, the term "substantially" or "essentially" or "approximately" corresponds to an approximate value of ±10%, preferably ±5%, and very preferably ±1%.

[0048] The present invention relates to an apparatus and a process for fluid catalytic cracking (FCC) for chemical conversion of petroleum products, for example for high severity catalytic cracking (HS-FCC).

[0049] The FCC unit usually processes the heavy fraction obtained from the 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 lighter fractions, such as gasoline fractions or gas oil fractions, alone or as a mixture. It is also possible to process a mixture of light fractions and heavy fractions, or to process whole crude oil. In order to increase the yield of propylene and ethylene by using highly severe reaction conditions (high temperature, extremely short contact time, high C / O ratio between catalyst flow C and feed flow O), catalytic cracking units and methods generally use co-current gas-solid downflow fluidized bed reactors ("downflow bed" or "downflow reactor"), hereinafter referred to as downflow reactors.

[0050] However, downward gas-solid flow may face many technical challenges, including achieving uniform flow and mixing in the established flow section of the downflow reactor.

[0051] In order to overcome these drawbacks, it has been determined to modify the downflow reactor technology described in patent FR 2 753 453 B1 to meet the above challenges by using an obstacle that can be inserted in the mixing chamber or downstream of the mixing chamber, ie in the downflow reactor.

[0052] The device according to the invention

[0053] refer to Figure 1 , the device according to one or more embodiments of the present invention comprises from top to bottom:

[0054] - Pipeline 1;

[0055] - mixing chamber 2; and

[0056] - Downflow reactor 3.

[0057] The pipeline 1 is suitable for feeding solid catalyst (particles) into the mixing chamber 2. The pipeline 1 mainly transports solids and fluidizing gas entrained by the solids flowing downward. The pipeline 1 has a riser-like flow well known to those skilled in the art.

[0058] The mixing chamber 2 is connected to the conduit 1 , comprises side / vertical walls defining a central / vertical axis Z, and is suitable for feeding the downflow reactor 3 with a mixture comprising catalyst particles, hydrocarbon feedstock and optionally a diluent.

[0059] 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 catalyst particles to produce an effluent comprising at least partially coked catalyst and gaseous cracking products and optionally unconverted vaporized feedstock.

[0060] Specifically, refer to Figure 1, a pipe 1 feeds a descending flow 4 of (hot) catalyst particles to a mixing chamber 2, and the mixing chamber 2 comprises a plurality of first injectors 5 for injecting a hydrocarbon feedstock 6. According to one or more embodiments, the (one or more) first injectors 5 are suitable for injecting a diluent (e.g. steam) together with the feedstock. According to one or more embodiments, the mixing chamber 2 comprises one or more second injectors 7 for injecting a diluent 8. In the mixing chamber 2, the descending flow 4 is in contact with the hydrocarbon feedstock 6 atomized by the (one or more) first injectors 5, and optionally with the diluent 8 introduced, for example, by the (one or more) second injectors 7.

[0061] Advantageously, the injection of diluent 8 makes it possible to reduce the partial pressure of the hydrocarbon feedstock and reduce side 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 selected from steam, nitrogen, CO2, light hydrocarbons (e.g. C1-C5 compounds) and combustion flue gases. According to one or more embodiments, the diluent 8 comprises steam or consists of steam.

[0062] According to one or more embodiments, the conduit 1 has a geometric shape with a constant cross section, such as a cylinder, square, rectangle or hexagon, or a geometric shape with a variable cross section, such as a truncated cone or a truncated cone, or a combination of various geometric shapes. According to one or more embodiments, the conduit 1 is cylindrical in shape and optionally has a variable diameter. According to one or more embodiments, the conduit 1 is at least partially truncated conical in shape. According to one or more embodiments, the conduit 1 comprises (in the flow direction of the solid catalyst): a cylindrical portion, the diameter of which is selected, for example, to obtain a flow rate of 100 to 800 kg / (m 2 s) and preferably 300 to 600 kg / (m 2 s) solid flow rate; adjacent to the mixing chamber 2, the frustoconical ("narrowing") portion, the diameter of which is reduced, for example, in order to achieve 400 to 2000 kg / (m 2 s) and preferably 700 to 1500 kg / (m 2 s) solid flow; and an optional second cylindrical portion, the diameter of which is selected, for example, to obtain a solid flow of 400 to 2000 kg / (m 2 s) and preferably 700 to 1500 kg / (m 2 s) of solid flow rate.

[0063] According to one or more embodiments, the mixing chamber 2 has a geometric shape with a constant cross section, such as a cylinder, square, rectangle or hexagon, or a geometric shape with a variable cross section, such as a truncated cone or a truncated cone, or a combination of various geometric shapes. According to one or more embodiments, the mixing chamber 2 is cylindrical in shape and optionally has a variable diameter. According to one or more embodiments, the mixing chamber 2 is at least partially truncated conical in 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 pipeline 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.

[0064] According to one or more embodiments, the mixing chamber 2 comprises 2 to 12 first injectors 5 , preferably 3 to 8 first injectors 5 .

[0065] According to one or more embodiments, the mixing chamber 2 comprises 2 to 12 second injectors 7 , preferably 3 to 8 second injectors 7 .

[0066] According to one or more embodiments, the injectors 5 and / or 7 are arranged inclined upward or downward or substantially horizontally.

[0067] According to one or more embodiments, the injectors 5 and / or 7 are inclined upwards, for example at an angle of 10° to 45° relative to the horizontal.

[0068] refer to Figure 1 According to one or more embodiments, the first injectors 5 and / or the second injectors 7 are arranged in one or more horizontal rows, i.e. rows perpendicular to the center / vertical axis Z of the mixing chamber 2. According to one or more embodiments, the second injectors 7 are arranged below the first injectors 5 (e.g., the first injector row). According to one or more embodiments, the second injectors 7 are arranged between two first injector 5 rows.

[0069] According to one or more embodiments, the radial position of the second injector 7 is located in the interval space between the adjacent radial positions of the two first injectors 5. According to one or more embodiments, the second injector 7 is located at substantially half of the separation angle of the two first injectors 5.

[0070] refer to Figure 2 and Figure 3According to one or more embodiments, at least one first injector 5 and / or at least one second injector 7 is rotated by an angle of 0° to 45°, and preferably 10° to 20°, relative to the radial direction of the diameter D of the mixing chamber 2, i.e., the projection of the axis of the injector 7 on the horizontal plane forms the said angle with the radial direction of the diameter D of the mixing chamber 2, and the radial direction of the diameter D of the mixing chamber 2 is perpendicular to the center / vertical axis Z.

[0071] refer to Figure 1 , the mixing chamber 2 feeds a mixture of hydrocarbon feedstock 6, catalyst particles and optional diluent 8 to the downflow reactor 3. Advantageously, the hydrocarbon feedstock 6 and the catalyst particles initiate a cracking reaction, which is completed in the downflow reactor 3 having a length L (along the central / vertical axis Z) to produce a hydrocarbon effluent comprising cracked products, spent catalyst and possibly a portion of unreacted hydrocarbon feedstock. The length L of the downflow reactor 3 is typically 2 m to 25 m.

[0072] According to one or more embodiments, the downflow reactor 3 has a cross-sectional constant geometry, such as cylindrical, square, rectangular or hexagonal, and 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.

[0073] According to the invention, the inner wall of the mixing chamber 2 and / or the downflow reactor 3 comprises one or more obstacles 9. Advantageously, the obstacles 9 are suitable for homogenizing the concentration of catalyst particles. In particular, the obstacles 9 make it possible to redistribute catalyst particles that may accumulate near the walls (e.g., the walls of the mixing chamber 2 and the downflow reactor 3).

[0074] According to the invention, the radial position of at least one obstacle 9 on the inner wall of the mixing chamber 2 and / or the downflow reactor 3 is discontinuous. In the present application, the term "discontinuous obstacle" means that the obstacle 9 occupies less than 90%, preferably less than 80%, very preferably less than 70% of the circumference of the inner wall of the mixing chamber 2 and / or the downflow reactor 3. According to one or more embodiments, the obstacle 9 occupies 15% to 80%, preferably 30% to 70%, very preferably 40% to 60% of the circumference of the inner wall of the mixing chamber 2 and / or the downflow reactor 3. Therefore, at least one obstacle 9 is not a continuous shape, i.e. an annular shape.

[0075] The obstacle 9 can have a variety of geometric shapes. According to one or more embodiments, the obstacle 9 is in the shape of a cube, a tetrahedron, a parallelepiped, a prism (e.g. a prism with a triangular, square, rectangular, hexagonal, circular or elliptical base) or a cone (e.g. a cone with a triangular, square, rectangular, hexagonal, circular or elliptical base) or a frustoconical shape, for example, forming a separate element on the wall of the mixing chamber 2. According to one or more embodiments, the base is substantially perpendicular to the vertical axis Z.

[0076] According to one or more embodiments, the obstacle 9 is arranged to prevent accumulation of catalyst particles on the obstacle 9. According to one or more embodiments, the obstacle 9 includes a lower portion (lower end surface) wider than an upper portion (upper end surface).

[0077] According to one or more embodiments, the obstacle 9 is arranged to distribute the catalyst particles towards the feed injection region of the mixing chamber 2, where the hydrocarbon concentration is higher. According to one or more embodiments, the obstacle 9 comprises an inclined upper surface that descends laterally (ie, along the wall of the mixing chamber 2).

[0078] According to one or more embodiments, the obstacle 9 is arranged to distribute the catalyst particles substantially towards the inside, for example towards the vertical axis Z, where the hydrocarbon concentration is higher. According to one or more embodiments, the obstacle 9 comprises an inclined upper surface descending from the outside to the inside.

[0079] According to one or more embodiments, the obstacle 9 is positioned in the mixing chamber 2 upstream of at least one first injector 5 for injecting the hydrocarbon feedstock 6 and / or at least one second injector 7 for injecting the diluent 8. Advantageously, the obstacle 9 makes it possible to guide the catalyst particles to the injectors and increase the contact, in particular with the hydrocarbon feedstock 6. According to one or more embodiments, the radial position of the obstacle 9 in the mixing chamber 2 is located in the spacing space between adjacent radial positions of two (e.g., first) injectors.

[0080] According to one or more embodiments, the obstacle 9 is positioned downstream of at least one first injector 5 for injecting hydrocarbon feedstock 6 and / or downstream of at least one second injector 7 for injecting diluent 8. According to one or more embodiments, the obstacle 9 is positioned downstream of at least one first or second injector at an axial distance of 0*L to 0.3*L, and preferably 0.01*L to 0.1*L.

[0081] According to one or more embodiments, the obstacle 9 is disposed in the downflow reactor 3 at an axial distance H of 0*L to 0.9*L, preferably 0.01*L to 0.6*L, for example 0.01*L to 0.4*L from the mixing chamber 2. i (For example, H 1 , H2 etc.) positioning.

[0082] According to one or more embodiments, the obstacle rows 11 are spaced apart at a distance of 0.05*L to 0.4*L. Figure 2 According to one or more embodiments, the device according to the invention comprises at least one row of obstacles 9, arranged at a predetermined height of the inner wall of the mixing chamber 2 and / or the downflow reactor 3, relative to the central / vertical axis Z. According to one or more embodiments, the obstacles 9 in the row 11 of obstacles thus arranged in a "string" are positioned substantially equidistant from one another. Advantageously, the row 11 of obstacles comprises (all) the obstacles 9 in a horizontal plane perpendicular to the central / vertical axis Z.

[0083] According to one or more embodiments, the obstacle row 11 occupies 15% to 80% of the circumference of the inner wall of the mixing chamber 2 and / or downflow reactor 3, and preferably 30% to 70%, such as 40% to 60%.

[0084] According to one or more embodiments, the obstacle row 11 reduces the flow area of ​​the inner wall of the mixing chamber 2 and / or the downflow reactor 3 by 1% to 35%, and preferably by 5% to 20%, such as by 10% to 20%.

[0085] According to one or more embodiments, the obstacle row 11 comprises at least 2 obstacles 9 , for example 2 to 24 obstacles 9 , preferably 4 to 12 obstacles 9 .

[0086] According to one or more embodiments, the obstacle row 11 in the mixing chamber 2 comprises at least 2 obstacles 9 , such as 2 to 24 obstacles 9 , preferably 4 to 12 obstacles 9 , such as 4 obstacles 9 .

[0087] According to one or more embodiments, the number of obstacles 9 in obstacle row 11 in mixing chamber 2 is an integer multiple of the number of first injectors 5. According to one or more embodiments, obstacle row 11 in mixing chamber 2 includes the same number of obstacles as first injectors 5.

[0088] According to one or more embodiments, the obstacle row 11 in the downflow reactor 3 comprises at least 2 obstacles 9 , for example 2 to 24 obstacles 9 , preferably 3 to 12 obstacles 9 , very preferably 4 to 8 obstacles 9 , for example 8 obstacles 9 .

[0089] According to one or more embodiments, the number of obstacles in the obstacle row 11 in the downflow reactor 3 is an integer multiple of the number of first injectors 5. According to one or more embodiments, the obstacle row 11 in the downflow reactor 3 includes the same number of obstacles as the first injectors 5.

[0090] According to one or more embodiments, the mixing chamber 2 comprises 0 to 4 obstacle rows 11, for example 1 obstacle row 11 is preferably positioned above the (eg first) injector.

[0091] According to one or more embodiments, the downflow reactor 3 comprises at least 1 obstacle row 11 , for example 1 to 10 obstacle rows 11 , preferably 2 to 8 obstacle rows 11 , very preferably 3 to 6 obstacle rows 11 , for example 3 obstacle rows 11 .

[0092] According to one or more embodiments, the downflow reactor 3 comprises:

[0093] - at an axial distance H of 0*L to 0.9*L from the mixing chamber 2 1 Positioning the first obstacle row 11;

[0094] - a second row of obstacles 11 preferably positioned at an axial distance of 0.05*L to 0.4*L from the first row of obstacles 11; and

[0095] A third row of obstacles 11 , preferably positioned at an axial distance of 0.05*L to 0.4*L from the previous row of obstacles 11 .

[0096] According to one or more embodiments, the mixing chamber 2 comprises 1 obstacle row 11, which is preferably positioned above the (e.g., first) injector, and the downflow reactor 3 comprises at least 1 obstacle row 11, for example 1 to 10 obstacle rows 11, preferably 2 to 8 obstacle rows 11, very preferably 3 to 6 obstacle rows 11, for example 3 obstacle rows 11, and the distance between the two rows is preferably 0.05*L to 0.4*L.

[0097] According to one or more embodiments, the radial position of an obstacle 9 in an obstacle row 11 is located in the spacing space between the radial positions of two adjacent obstacles 9 in an adjacent obstacle row 11, i.e., each obstacle row 11 has a rotation (about the vertical axis Z) relative to the adjacent obstacle row 11. According to one or more embodiments, the radial position of an obstacle 9 in an obstacle row 11 is rotated by an angle of 10° to 35°, preferably 15° to 30°, and preferably by an angle of 180° / N, wherein N is the number of obstacles in the row. According to one or more embodiments, the obstacle rows 11 are positioned relative to each other so as to together cover the entire circumference of the inner wall of the mixing chamber 2 and / or the downflow reactor 3 when viewed along the vertical axis Z.

[0098] Furthermore, compared to crown-shaped internal components that are capable of significantly reducing the flow area and increasing the gas velocity in the central region of the downflow reactor 3, which is capable of producing a parabolic flow distribution away from plug flow, the (one or more) obstacle rows 11 according to the present invention make it possible to homogenize the catalyst flow without significantly reducing the flow area of ​​the downflow reactor 3.

[0099] refer to Figure 3 According to one or more embodiments, at least a portion of the mixing chamber 2 includes a central plug 12, which is basically arranged along the central / vertical axis Z and defines an annular opening 13 in the mixing chamber 2, through which catalyst particles are discharged and / or flow into the mixing chamber 2.

[0100] catalyst

[0101] The catalyst is a solid catalyst (e.g., particles having a density, size, and shape of particles selected for use in a fluidized bed). The density, size, and shape of catalysts for use in a fluidized bed are known to those skilled in the art and will not be described in detail. The catalyst may be any type of catalytic cracking catalyst.

[0102] According to one or more embodiments, the catalyst is an FCC catalyst containing, for example, a matrix made of clay, silica or silica-alumina, optionally a binder and / or a zeolite, for example containing 15% to 70% by weight of zeolite, preferably zeolite Y and / or zeolite ZSM-5, relative to the weight of the catalyst. According to one or more embodiments, the catalyst comprises zeolite ZSM-5. According to one or more embodiments, the particle density of the catalyst is 1000 kg / m 3 Up to 2000kg / m 3 According to one or more embodiments, the particle density of the catalyst is 1250 kg / m 3 Up to 1750kg / m 3 .

[0103] According to one or more embodiments, the catalyst comprises at least one binder (e.g., 30 to 85 wt %) selected from alumina, silica, silica-alumina, magnesia, titania, zirconia, clay and boria, alone or in a mixture, and preferably selected from silica, silica-alumina and clay, alone or in a mixture.

[0104] According to one or more embodiments, the catalyst comprises at least one doping element (e.g., 0 to 10 wt %) selected from phosphorus, magnesium, sodium, potassium, calcium, iron, boron, manganese, lanthanum, cerium, titanium, tungsten, molybdenum, copper, zirconium and gallium, alone or in a mixture.

[0105] According to one or more embodiments, the catalyst comprises and / or consists of an optionally doped zeolite such as ZSM-5.

[0106] raw material

[0107] According to one or more embodiments, the hydrocarbon feedstock 6 is a heavy feedstock characterized by an initial boiling point close to 340° C., typically above 380° C., such as a heavy fraction, for example obtained from a vacuum distillation unit, such as vacuum gas oil (VGO) / vacuum distillate or vacuum residue, atmospheric residue, a vacuum gas oil obtained from a conversion unit, such as coker gas oil (heavy coker gas oil (HCGO)) or a heavy fraction obtained from an ebullated-bed or entrained-bed hydroconversion unit, such as H-Oil, LC-Fining, EST, VCC or Uniflex processes, a recycle stream from a hydrocracking step, alone or as a mixture.

[0108] According to one or more embodiments, the hydrocarbon feedstock 6 is a light feedstock characterized by a final boiling point below 450° C., typically below 400° C., such as a gasoline fraction or a gas oil fraction, such as obtained from an atmospheric distillation unit, or obtained 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 an ebullating bed or entrained bed hydroconversion unit (such as H-Oil, LC-Fining, EST, VCC or Uniflex processes), or gasoline or gas oil obtained from an FCC unit, or a recycle stream from an associated FCC unit, alone or as a mixture. According to one or more embodiments, a mixture of light and heavy fractions or whole crude oil can also be processed.

[0109] Upon contact with the descending flow 4 of hot catalyst particles, the atomized hydrocarbon feedstock 6 is vaporized and undergoes endothermic cracking reactions along the downflow reactor 3, thereby reducing the temperature and producing:

[0110] - Upgradable products (e.g., C1-C4 gas containing olefins; gasoline fraction containing aromatics);

[0111] - optionally a light gas oil fraction (light cycle oil (LCO));

[0112] - optionally a heavy gas oil fraction (heavy cycle oil (HCO));

[0113] - optionally oil in the form of a slurry; and

[0114] - Optional solid residue (coke) adsorbed on the catalyst.

[0115] Method according to the invention

[0116] The process according to the invention comprises a catalytic cracking stage for catalytically cracking a hydrocarbon feedstock 6 (fed via a first injector 5) by contacting it in a mixing chamber 2 and then in a downflow reactor 3 with a descending flow 4 of hot catalyst particles (fed via a conduit 1) and optionally a diluent 8 (fed via a second injector 7) to produce light olefins (and in particular ethylene and propylene), aromatics (and in particular benzene, toluene and xylenes) and gasoline (and optionally LCO, HCO and slurry oil).

[0117] 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 fluidization state, preferably with a flow rate of more than 200 kg / m 2 s mass flow rate, so as to preferably achieve a state with descending bubbles, for example.

[0118] 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.

[0119] In the present patent application, the term "homogeneous fluidized bed" refers to 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, shape of the particles, etc.). 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).

[0120] In the present patent application, the term "bubbling fluidized bed" refers to a gas-solid fluidized bed whose gas velocity is between the minimum bubbling velocity and the velocity of transition to the turbulent state. These velocities depend on the properties of the solid catalyst (density, size, shape of the particles, etc.). The volume fraction of solids is between a value close to 0.35 and a value close to 0.45.

[0121] In the present patent application, the term "turbulent fluidized bed" refers to a gas-solid fluidized bed whose gas velocity is between the velocity of transition to the turbulent state and the transport velocity. The solid volume fraction is between a value close to 0.25 and a value close to 0.35.

[0122] In this patent application, the term "transport fluidized bed" refers to a gas-solid fluidized bed whose gas velocity is greater than the transport velocity. The volume fraction of solids is less than a value close to 0.25. In this patent application, the term "transport velocity" corresponds to the velocity at which substantially all solids are entrained by the gas.

[0123] According to one or more embodiments, the injector 5 is adapted to atomize the hydrocarbon feedstock 6 (liquid) and penetrate the catalyst stream.

[0124] According to one or more embodiments, the operating conditions of pipeline 1 and / or downflow reactor 3 are selected from the following conditions:

[0125] - the temperature (at the reactor outlet) is from 520°C to 750°C, and preferably below 650°C;

[0126] - Absolute total pressure is 0.1MPa to 0.5MPa;

[0127] - 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);

[0128] -Contact time t of hydrocarbon feedstock 6 and catalyst c Less than 10 seconds, preferably 0.5 to 4 seconds;

[0129] - The mass flow rate of catalyst particles is 50 to 850 kg / (m 2 s), preferably 400 to 750 kg / (m 2 s); and

[0130] - The superficial gas velocity is 2 to 26 m / s, preferably 6 to 16 m / s.

[0131] In this specification, the contact time t c Limited to the solid volume fraction ε s With bed height H s The product of (e.g., reactor height L) divided by the superficial gas velocity sgv is integrated along the bed height as defined by the following mathematical formula Math 1.

[0132] Math 1

[0133]

[0134] 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 hydrocarbons in the feedstock, and the diluent is introduced in an amount of 0% or 0.1 wt. % to 40 wt. %, preferably 1 wt. % to 35 wt. %, and preferably 1 wt. % to 30 wt. %, relative to the mass of the hydrocarbon feedstock 6.

[0135] According to one or more embodiments, at the end of the catalytic cracking stage in the downflow reactor 3, the gaseous products and catalyst and optionally unconverted vaporized feedstock are separated in a gas / solid separator (not shown) containing a dense fluidized bed, where the cracking reaction can continue.

[0136] According to one or more embodiments, the operating conditions of the separator are selected from the following conditions:

[0137] - the temperature (at the reactor outlet) is from 500° C. to 750° C., preferably from 550° C. to 700° C., and even more preferably from 580° C. to 685° C.;

[0138] - 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;

[0139] - the weight ratio C / O of catalyst to feedstock (unconverted vaporized feedstock to gaseous products) is from 5 (kg / h) / (kg / h) to 40 (kg / h) / (kg / h);

[0140] - Contact time t between feedstock and catalyst c 500 milliseconds (ms) to 10 seconds; and

[0141] - 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 preferably from 0.05 MPa to 0.15 MPa.

[0142] According to one or more embodiments, at the outlet of the separator, the coked catalyst is sent to an optional stripping column (not shown) in order to strip the hydrocarbons still adsorbed on the catalyst surface by means of a second diluent.

[0143] According to one or more embodiments, the operating conditions of the stripping column are selected from the following conditions:

[0144] - Catalyst residence time in the stripping tower: 10 seconds to 180 seconds, preferably 30 seconds to 120 seconds;

[0145] - the superficial gas velocity is between the minimum fluidization velocity and the transition velocity to the turbulent state, for example, 0.01 m / s to 0.5 m / s, preferably 0.15 m / s to 0.4 m / s;

[0146] -Solid flow rate is 25kg / m 2 s to 200kg / m 2 s, preferably 50kg / m 2 s to 150kg / m 2 s, and preferably 50kg / m 2 s to 100kg / m 2 s;

[0147] - a temperature of 500°C to 750°C, preferably 550°C to 650°C;

[0148] - 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;

[0149] - Solid volume fraction is from 0.25 to 0.6, preferably from 0.4 to 0.6.

[0150] According to one or more embodiments, at the outlet of the separator or stripper, the coked solids are conveyed to a regenerator (not shown) where an air supply burns the coke off the catalyst to produce hot regenerated catalyst and combustion gases which can feed hot catalyst particles downstream 4 .

[0151] According to one or more embodiments, the operating conditions of the regenerator are selected from the following conditions:

[0152] - superficial gas velocity is 0.1m / s to 2m / s, preferably 0.2m / s to 1.5m / s;

[0153] - the residence time of the catalyst is from 30 seconds to 20 minutes, preferably from 1 minute to 10 minutes;

[0154] - The temperature is from 500°C to 840°C, preferably from 650°C to 750°C. Example

[0155] refer to Figure 3 , in order to study the fluid dynamics, the flows in a reference apparatus A operated under non-reactive conditions and an apparatus B according to the invention were compared.

[0156] The reference device A and the device B according to the invention comprise:

[0157] - a pipe 1 consisting of a cylindrical section, a narrowing cone and a cylindrical section;

[0158] - a frustoconical mixing chamber 2 (S1 / S2 less than 1) comprising a central plug 12 defining an annular orifice 13;

[0159] - a cylindrical downflow reactor 3 having a length of 4.07 m and an internal diameter of 0.42 m;

[0160] - four first injectors 5 for injecting hydrocarbon feedstock 6, positioned countercurrently to the downward flow 3 of catalyst particles at an upward angle of 30° with respect to the horizontal; and

[0161] - Four second injectors 7 for injecting diluent 8 (steam), positioned countercurrently to the downward flow 3 of the catalyst particles, at an upward angle of 30° with respect to the horizontal.

[0162] Reference device A has no obstacles positioned on the inner wall.

[0163] The device according to the invention has three obstacle rows 11, which are positioned on the wall of the downflow reactor 3. Each obstacle row 11 comprises 8 prisms of isosceles triangular cross section, whose base is 0.07 m and whose height is 0.096 m. In the present embodiment, the base of the prism is perpendicular to the vertical axis Z. The circumference occupied by the obstacles 9 in the obstacle row 11 is 46% of the total circumference of the downflow reactor 3. The cross section occupied by the obstacles 9 in the obstacle row 11 is 16% of the cross section of the downflow reactor 3.

[0164] The first, second and third obstacle rows 11, 11 are located at distances of 0.4 m, 0.6 m and 1.4 m, respectively, from the first injector 5 for injecting the hydrocarbon feedstock 6. Each obstacle row 11 is rotated 22.5° relative to the previous obstacle row 11, in order in particular to direct the catalyst particles flowing between the two obstacles 9 to a more dilute region.

[0165] Use in CFD The tool simulates the configuration of a reference device A and a device B according to the invention under the following operating conditions:

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

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

[0168] - The air flow rate of 1.85 kg / s indicates that the ratio of the first injector 5 to the second injector 7 is 70 / 30;

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

[0170] - The rotation angle 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, and 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] A central plug 12 is positioned in the centre of the mixing chamber 2 .

[0174] Figure 4The particle volume fraction (denoted as VFP) of two configurations A and B of a reference device A and a device B according to the invention is shown on 13 cross sections. The first two cross sections are at the level of the first injector 5, the second injector 7 respectively, while the following cross sections are spaced 0.35 m apart.

[0175] Advantageously, the radial distribution of solids throughout the downflow reactor 3 is always more uniform for the device B according to the invention than for the reference device A. Furthermore, a higher solids concentration near the wall can be noted for the reference device A than for the device B according to the invention.

[0176] Figure 5 They are shown respectively Figure 3 Radial distributions A and B of the particle volume fraction VFP and the particle mass flow rate (expressed as MFP) of the reference device A and the device B according to the invention in the figure. The radial distributions A and B are produced in the x-direction (perpendicular to the vertical axis Z) at a height of 2.8 meters below the first injector 5. It is worth noting that the device B according to the 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 15% for the reference device A and 5% for the device B according to the invention. Similarly, the coefficient of variation of the particle mass flow rate MFP values ​​on the distributions A and B is 16% for the reference device A and 5% for the device B according to the invention, which shows that for the device B according to the invention, the dispersion of the catalyst in the cross section is better.

Claims

1. A device for co-current gas-solid downflow fluidized catalytic cracking, from top to bottom include: - a conduit (1) suitable for conveying a downward flow (4) of catalyst particles; a mixing chamber (2) connected to the pipeline (1) and adapted to be fed with a descending flow (4) through the pipeline (1), the mixing chamber (2) comprising an inner wall, at least one first injector (5) for injecting a hydrocarbon feedstock (6); and a co-current gas-solid downflow fluidized bed reactor (3) connected to the mixing chamber (2) and adapted to be fed with a mixture comprising catalyst particles and a hydrocarbon feedstock through the mixing chamber (2), the co-current gas-solid downflow fluidized bed reactor (3) comprising an inner wall; The inner wall of the mixing chamber (2) and / or the co-current gas-solid downflow fluidized bed reactor (3) comprises one or more discontinuous obstacles (9).

2. The apparatus according to claim 1, wherein the obstacles (9) are adapted to distribute the catalyst particles substantially towards the interior of the mixing chamber (2) and / or the co-current gas-solid downflow fluidized bed reactor (3).

3. An apparatus according to claim 1 or claim 2, wherein the obstacle (9) comprises an upper surface which is inclined and descends inwardly.

4. The device according to any of the preceding claims, wherein the obstacle (9) is adapted to prevent accumulation of catalyst particles on said obstacle (9).

5. Device according to any of the preceding claims, wherein the obstacles (9) are adapted to distribute the catalyst particles along the walls of the mixing chamber (2).

6. Device according to any of the preceding claims, wherein the obstacle (9) comprises an inclined and laterally descending upper surface.

7. Device according to any of the preceding claims, wherein the obstacle (9) is prismatic, cylindrical, pyramidal, conical and / or frustoconical in shape.

8. Device according to any of the preceding claims, wherein an obstacle (9) is arranged in the mixing chamber (2) upstream of the at least one first injector (5).

9. An apparatus according to any of the preceding claims, wherein the obstacle (9) is positioned in the downflow reactor (3) at an axial distance Hi of 0*L to 0.9*L from the mixing chamber (2), L being the length of the co-current gas-solid downflow fluidized bed reactor (3).

10. The device according to any of the preceding claims, comprising at least one obstacle row (11) arranged at a predetermined height of the inner wall of the mixing chamber (2) and / or the downflow reactor (3).

11. The device according to claim 10, wherein the circumference of the inner wall of the mixing chamber (2) and / or the downflow reactor (3) is occupied by the obstacle row (11) by 15% to 80%.

12. Apparatus according to claim 10 or claim 11, wherein the row of obstacles (11) reduces the flow area of ​​the inner wall of the mixing chamber (2) and / or the downflow reactor (3) by 1% to 35%.

13. The device according to any one of claims 10 to 12, wherein the obstacle row (11) in the mixing chamber (2) comprises 2 to 24 obstacles (9), and / or the obstacle row (11) in the downflow reactor (3) comprises 2 to 24 obstacles (9).

14. The device according to any one of claims 10 to 13, wherein the radial position of an obstacle (9) in one obstacle row (11) is located in the interval between the radial positions of two adjacent obstacles (9) of an adjacent obstacle row (11).

15. A method for co-current gas-solid downflow catalytic cracking, The following steps are involved: - a downward flow (4) of catalyst particles conveying a dense phase in the pipeline (1); - feeding a mixing chamber (2) through a conduit (1) with a downflow (4), the mixing chamber (2) comprising an inner wall and at least one first injector (5) for injecting a hydrocarbon feedstock (6); - feeding a mixture comprising catalyst particles and a hydrocarbon feedstock into a co-current gas-solid downflow fluidized bed reactor (3) through a mixing chamber (2), the co-current gas-solid downflow fluidized bed reactor (3) comprising an inner wall; and - at least partially cracking a hydrocarbon feedstock (6) in the presence of catalyst particles in a co-current gas-solid downflow fluidized bed reactor (3) to produce an effluent (10) comprising at least partially coked catalyst and gaseous cracking products; The inner wall of the mixing chamber (2) and / or the co-current gas-solid downflow fluidized bed reactor (3) includes a plurality of obstacles (9).

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