Catalytic cracking secondary feed nozzle and method of use thereof

Abstract

The present application relates to the field of catalytic cracking technology in oil refining industry, and particularly relates to a catalytic cracking secondary feed nozzle and an application method thereof. The nozzle comprises: an inlet contraction section, a throat section, a secondary mixing section, a secondary throat section, an outlet secondary atomization section and a bypass channel penetrating through the inlet and outlet of the nozzle; the inlet contraction section, the throat section, the secondary mixing section, the secondary throat section and the outlet secondary atomization section are sequentially communicated; the inlet contraction section, the secondary mixing section and the outlet secondary atomization section are communicated with the bypass channel. The present application provides a catalytic cracking secondary feed nozzle which does not need to set a nozzle mounting sleeve on the opening of the lifting wall and is convenient for industrial reconstruction and application on the basis of the existing catalytic cracking riser reactor device. The nozzle can strengthen the mixing and atomization of the pre-lifting medium and the secondary feed, does not cause excessive pressure drop, has a simple structure, is convenient to use and has good operation flexibility.

Description

Technical Field

[0001] This invention relates to the field of catalytic cracking technology in the oil refining industry, and in particular to a secondary feed nozzle for catalytic cracking and its application method. Background Technology

[0002] Existing technologies include patents related to catalytic cracking in the oil refining industry, including Chinese patents.

[0003] CN201610476268.1, "A Novel Atomizing Feed Nozzle for Catalytic Cracking," discloses a feed nozzle comprising a nozzle head, a throat, an outer tube, an inner tube, a feed oil inlet, a steam inlet, and a steam orifice plate. The steam orifice plate is disposed between the throat and the outer tube, and connected to the inner tube. An annular cavity is formed between the steam orifice plate, the outer tube, and the inner tube to constitute a steam chamber. A steam inlet is disposed on the steam chamber. A mixing atomization chamber is formed between the steam orifice plate, the outlet of the inner tube, and the inlet of the constriction section of the throat. The throat has a contraction-expansion atomization zone, i.e., an expansion section, a throat section, and a contraction section. Multiple steam nozzles are distributed circumferentially on the steam orifice plate, and multiple nozzle outlets are distributed circumferentially on the nozzle head. The nozzle outlet structure is a throat type, consisting of a contraction section, a throat section, and an expansion section. This structure allows for third-stage atomization of the feed oil, while simultaneously forming a deceleration zone in the expansion section, effectively solving the problem of severe catalyst breakage caused by excessively high feed oil droplet injection velocity. However, this technology has shortcomings and defects. It was not specifically developed for secondary heavy hydrocarbon feed and cannot solve the following two problems: First, the pressure gradient is large and the nozzle operation is unstable due to the rapid increase in volumetric flow rate caused by the rapid gasification of heavy hydrocarbons. Second, if the above-mentioned nozzle installation method is adopted, on the one hand, the secondary feed cannot quickly reach the center of the riser to cover the entire cross section, and on the other hand, it also cannot solve the problems of rapid increase in volumetric flow rate, large pressure gradient and unstable operation caused by the rapid gasification of heavy hydrocarbons.

[0004] Chinese patent CN201620539374.5, "A Cyclone Bubble Atomizing Catalytic Cracking Feed Nozzle," discloses a feed nozzle comprising a primary steam inner channel, a feed oil channel, a secondary steam outer ring channel, primary steam orifices, a cyclone separator, a mixing chamber, a contraction section, a throat, an expansion section, secondary steam orifices, a nozzle head, and spray holes. The primary steam inner channel has a ring of primary steam orifices evenly distributed circumferentially. A cyclone separator is installed between the primary steam inner channel and the feed oil channel. The secondary steam orifices are evenly distributed circumferentially on the expansion section, and steam is injected into the feed oil from the secondary steam outer ring channel. The nozzle head is a hemispherical nozzle with three rings of spray holes evenly distributed circumferentially on its end face. However, this technology has the following shortcomings: it is not specifically developed for secondary heavy hydrocarbon feedstocks. The above two problems cannot be solved either. First, the rapid gasification of heavy hydrocarbons leads to a surge in volumetric flow rate, resulting in a large pressure gradient and unstable nozzle operation. Second, if the above nozzle installation method is adopted, on the one hand, the secondary feed cannot quickly reach the center of the riser to cover the entire cross-section, and on the other hand, it also cannot solve the problems of rapid gasification of heavy hydrocarbons leading to a surge in volumetric flow rate, large pressure gradient, and unstable operation.

[0005] Furthermore, from a structural perspective, domestic feed atomizing nozzles are mainly divided into five types: First, the throat type (i.e., composed of a contraction section + throat section + expansion section and its deformation), such as patents ZL89207961.9, ZL90209410.6, and ZL201610476268.1; second, a swirl structure is set inside the nozzle, such as patent ZL98233035.9; third, a porous steam distributor is set inside the nozzle, such as patent Z L00109776.8, ZL200620130509.9; fourth, multi-stage atomized steam, such as ZL99219391.5; fifth, combinations of the above four structures, such as patents ZL200420066089.3 (swirl + throat type), 201120138650.4 (two-stage atomization + throat type), ZL201620539374.5 (swirl + two-stage atomization + throat type), etc. Similar technologies abroad mainly include S&W's target nozzle, UOP's multi-hole Optimix nozzle with built-in multi-hole steam distributor, Mobile and Kellogg's ATOMAX nozzle with built-in multi-hole steam distributor and baffle, ABB Lummus's feed nozzle with nozzle cap capable of forming a flat jet, and Exxon's nozzle with secondary atomized steam.

[0006] The above-mentioned feed atomizing nozzles were not specifically developed for secondary heavy hydrocarbon feed; their sole optimization goal is atomization effect. Therefore, using these nozzles for secondary heavy hydrocarbon feed cannot solve two problems: first, the pressure gradient and nozzle operation instability caused by the rapid gasification and surge in volumetric flow rate of heavy hydrocarbons; second, if the above-mentioned nozzle installation method is adopted, on the one hand, the secondary feed cannot quickly reach the center of the riser pipe to cover the entire cross-section, and on the other hand, it also cannot solve the problems of rapid gasification and surge in volumetric flow rate, large pressure gradient, and unstable operation of heavy hydrocarbons.

[0007] In addition, if the secondary feed is introduced directly from the bottom or simply mixed with the pre-lifting medium before being introduced into the pre-lifting section, the density of the secondary feed and the density of the pre-lifting medium differ by more than 200 times. This may cause severe impact and breakage of the catalyst in the pre-lifting section due to excessively high local density. Summary of the Invention

[0008] To address the shortcomings of the existing technology, this invention provides a secondary feed nozzle for catalytic cracking that eliminates the need for nozzle mounting sleeves with openings in the riser wall and facilitates industrial modification and application, based on the existing catalytic cracking riser reactor device. This nozzle can enhance the mixing and atomization of the pre-rise medium and the secondary feed without generating excessive pressure drop. It has a simple structure, is easy to use, and has good operational flexibility.

[0009] To achieve the above objectives, the present invention provides a catalytic cracking secondary feed nozzle, comprising:

[0010] The nozzle consists of an inlet constriction section, a throat section, a secondary mixing section, a secondary throat section, an outlet secondary atomization section, and a bypass channel that runs through the nozzle inlet and outlet.

[0011] The inlet contraction section, throat section, secondary mixing section, secondary throat section, and outlet secondary atomization section are connected in sequence.

[0012] The inlet shrinkage section, the secondary mixing section, and the outlet secondary atomization section are connected to the bypass channel.

[0013] In some embodiments, the inlet constriction section is a conical structure with a cone apex angle of 80°-90°; the throat section is a cylindrical structure.

[0014] In some embodiments, the secondary mixing section is a spindle-shaped structure with conical ends and a cylindrical middle section, with a front cone apex angle of 80°-90° and a rear cone apex angle of 80°-90°.

[0015] In some embodiments, the secondary throat segment is a cylindrical structure;

[0016] In some embodiments, the outlet secondary atomization section has a conical structure with a cone apex angle of 80°-90°.

[0017] In some embodiments, the length ratio range of each part of the inlet contraction section, throat section, secondary mixing section, secondary throat section and outlet secondary atomization section is I1:I2:(I3+I4+I5):I6:I7=(4-5):(3-4):(7-9):(1-2):(3-4); wherein the length ratio range of the upstream conical structure, the middle cylindrical structure and the downstream conical structure in the secondary mixing section is I3:I4:I5=(3-4):1:(3-4).

[0018] In some embodiments, the bypass channel has branches that communicate with the secondary mixing section and the outlet secondary atomization section, respectively.

[0019] In some embodiments, the number of bypass channels is two or more, and they are arranged symmetrically.

[0020] The present invention further provides an application of the above-described catalytic cracking secondary feed nozzle to a matching catalytic cracking riser device. The catalytic cracking riser device includes: a riser feed mixing section and a riser pre-lifting section connected in sequence, and also includes a pre-lifting medium pipeline. The pre-lifting pipeline is disposed in the riser pre-lifting section. A gas distributor is also provided in the riser pre-lifting section. A regeneration inclined pipe is connected to the outside of the riser pre-lifting section. A raw material feed pipe is connected to the outside of the riser feed mixing section.

[0021] The pre-lifting medium pipeline is provided with a secondary feed inlet, and the secondary feed nozzle is located at the outlet of the pre-lifting medium pipeline of the lifting pipe.

[0022] The present invention also provides a method for applying a secondary feed nozzle for catalytic cracking to a matching catalytic cracking riser unit, comprising the following steps:

[0023] Secondary heavy hydrocarbon feed enters from the pre-lifting medium pipeline and moves with the pre-lifting medium to the nozzle;

[0024] The nozzle mixes and atomizes the secondary heavy hydrocarbon feed with the pre-lifting medium before spraying it out.

[0025] The mixture of atomized secondary heavy hydrocarbon feed and pre-lifting medium reacts with the regenerated catalyst, and the reaction products and catalyst continue to move upward and react with the incoming feed oil.

[0026] The reaction products and deactivated catalyst flow out of the booster reactor outlet and enter the separation system;

[0027] The deactivated catalyst after separation is processed by the stripping unit and then regenerated in the regeneration reactor. The regenerated catalyst is returned to the bottom of the riser for recycling.

[0028] Compared with the prior art, the present invention has the following advantages:

[0029] By installing the secondary heavy hydrocarbon feed nozzle at the outlet of the pre-lifting medium pipeline, it is avoided to open additional holes on the riser reactor to install the nozzle, which reduces the difficulty of industrial modification and expands the applicability of the device.

[0030] By employing a certain proportion of secondary "contraction-expansion" structure, the mixing and atomization of secondary heavy hydrocarbon feed and pre-lifting medium can be further enhanced on the basis of primary atomization. This is beneficial for the contact between the secondary heavy hydrocarbon feed and the catalyst. In the "contraction-expansion" structure, the role of the contraction section is to enhance the mixing of secondary heavy hydrocarbon feed and pre-lifting medium. During the intense mixing process, the pre-lifting medium impacts and breaks up the secondary heavy hydrocarbon feed. The role of the expansion section is to effectively extend and thin the liquid film of the secondary heavy hydrocarbon feed in the sidewall region. Through secondary "contraction-expansion", the atomization effect is further enhanced.

[0031] Because of the bypass channel, the pressure difference between the inside and outside of the nozzle can be automatically balanced. Due to the large molecular weight of the heavy hydrocarbon secondary feed, the large number of atomized diesel droplets at the nozzle outlet come into contact with the hot catalyst, causing a surge in volumetric flow rate due to vaporization. Theoretically, volumetric flow rate is positively correlated with velocity by the first power, while pressure drop is positively correlated with velocity by the square. This means that a surge in volumetric flow rate can easily lead to a large pressure gradient, affecting the stable operation of the nozzle. The bypass channel's function is to regulate the pressure drop before and after the nozzle, making the pressure drop along the process more stable, and thus reducing nozzle pressure drop and energy consumption.

[0032] The catalytic cracking secondary feed nozzle provided by this invention does not require opening holes in the riser wall to install the nozzle with a sleeve. It has a simple structure, is convenient for industrial application, has low energy consumption, and good operational flexibility. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0034] Figure 1 This is a cross-sectional view of the catalytic cracking secondary feed nozzle shown in an embodiment of the present invention;

[0035] Figure 2 This is a top view of the catalytic cracking secondary feed nozzle shown in an embodiment of the present invention;

[0036] Figure 3 This is a schematic diagram illustrating the industrial application of a secondary feed nozzle for catalytic cracking, as shown in an embodiment of the present invention.

[0037] Figure 4 This is a schematic diagram illustrating the change in nozzle pressure drop before and after setting up the bypass channel, as shown in an embodiment of the present invention.

[0038] in:

[0039] 1-Secondary feed nozzle;

[0040] 11-Imported contraction segment;

[0041] 12-Laryngeal segment;

[0042] 13-Secondary mixing section;

[0043] 14-Secondary larynx segment;

[0044] 15 - Secondary atomization section at the outlet;

[0045] 16-Bypass lane;

[0046] 2- Feed mixing section via riser;

[0047] 3-Pre-lifting section of the riser pipe;

[0048] 4-Boosting medium pipeline;

[0049] 41 - Secondary feed inlet;

[0050] 5-Gas distributor;

[0051] 6-Regeneration inclined tube;

[0052] 7-Raw material feed pipe;

[0053] I1 - Length of the inlet contraction section;

[0054] I2 - Length of the larynx;

[0055] I3 - Length of the upstream conical structure of the secondary mixing section;

[0056] I4 - Length of the intermediate cylindrical structure in the secondary mixing section;

[0057] I5 - Length of the downstream conical structure of the secondary mixing section;

[0058] I6 - Length of the secondary laryngeal segment;

[0059] I7 - Length of the secondary atomization section. Detailed Implementation

[0060] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments to further understand the purpose, solution and effect of the present invention, but it is not intended to limit the scope of protection of the appended claims.

[0061] Certain terms are used in this specification and the following claims to refer to specific components or parts. Those skilled in the art will understand that users or manufacturers may use different names or terms to refer to the same component or part. This specification and the following claims do not distinguish components or parts by differences in name, but rather by differences in function. The terms "comprising" and "including" used throughout this specification and the following claims are open-ended and should be interpreted as "including but not limited to". Furthermore, the term "connection" here includes any direct and indirect electrical connection means. Indirect electrical connection means include connections made through other means.

[0062] It should be noted that in the description of this invention, the terms "lateral", "longitudinal", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and "about", or "approximately", "substantially", "left and right", etc., indicating the orientation or positional relationship or parameters, are all based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, a specific size, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0063] like Figure 1-2 As shown, this embodiment of the invention provides a catalytic cracking secondary feed nozzle 1, which includes: an inlet constriction section 11, a throat section 12, a secondary mixing section 13, a secondary throat section 14, an outlet secondary atomization section 15, and a bypass channel 16 penetrating the nozzle inlet and outlet; the inlet constriction section 11, the throat section 12, the secondary mixing section 13, the secondary throat section 14, and the outlet secondary atomization section 15 are sequentially connected; the inlet constriction section 11, the secondary mixing section 13, and the outlet secondary atomization section 15 are connected to the bypass channel 16.

[0064] The inlet contraction section 11 is a conical structure with a cone apex angle of 80°-90°, which can be 80° or 90°, but is not limited to this range; the throat section 12 is a cylindrical structure. The secondary mixing section 13 is a spindle-shaped structure with conical ends and a cylindrical middle section, with a front cone apex angle of 80°-90° and a rear cone apex angle of 80°-90°. Specifically, it can be set to a front cone apex angle of 80° and a rear cone apex angle of 90°, but is not limited to this. The secondary throat section 14 is a cylindrical structure; the outlet secondary atomization section 15 is a conical structure with a cone apex angle of 80°-90°, which can be 80°, 88°, 90°, etc., but is not limited to this.

[0065] The length ratio range of each part of the inlet contraction section 11, throat section 12, secondary mixing section 13, secondary throat section 14 and outlet secondary atomization section 15 is I1:I2:(I3+I4+I5):I6:I7=(4-5):(3-4):(7-9):(1-2):(3-4); and the length ratio range of the upstream conical structure, the middle cylindrical structure and the downstream conical structure in the secondary mixing section 13 is I3:I4:I5=(3-4):1:(3-4). Specifically, in this embodiment, the length ratio of each part of the upstream conical structure, intermediate cylindrical structure, downstream conical structure, secondary throat section 14, and outlet secondary atomization section 15 in the inlet contraction section 11, throat section 12, and secondary mixing section 13 is I1:I2:I3:I4:I5:I6:I7 = 4.2:3.5:3.5:1:3.3:1.6:3.7, but it is not limited to this, and can be within the aforementioned range.

[0066] The bypass channel 16 has branches that connect to the secondary mixing section 13 and the outlet secondary atomization section 15, respectively. There are two or more bypass channels 16, for example, four, arranged symmetrically. A comparison of pressure drop changes with and without bypass channels is attached. Figure 4 As shown, the bypass channel can effectively reduce the pressure drop value and pressure drop gradient, meaning that the bypass channel has a significant effect on the stable operation of high molecular weight feedstocks such as diesel fuel.

[0067] Another embodiment of the present invention provides a method for applying the catalytic cracking secondary feed nozzle 1 described in the above embodiment to a matching catalytic cracking riser device. The catalytic cracking riser device includes: a riser feed mixing section 2 and a riser pre-lifting section 3 connected in sequence, and also includes a pre-lifting medium pipeline 4. The pre-lifting pipeline 4 is disposed in the riser pre-lifting section 3. The riser pre-lifting section 3 is also provided with a gas distributor 5. The riser pre-lifting section 3 is externally connected to a regeneration inclined pipe 6. The riser feed mixing section 2 is externally connected to a raw material feed pipe 7.

[0068] The pre-lifting medium pipeline 4 is provided with a secondary feed inlet 41, and the secondary feed nozzle 1 is located at the outlet of the pre-lifting medium pipeline 4.

[0069] Another embodiment of the present invention further provides a method for applying a catalytic cracking secondary feed nozzle to a matching catalytic cracking riser unit, characterized by comprising the following steps:

[0070] Secondary heavy hydrocarbon feed enters from the pre-lifting medium pipeline and moves with the pre-lifting medium to the nozzle;

[0071] The nozzle mixes and atomizes the secondary heavy hydrocarbon feed with the pre-lifting medium before spraying it out.

[0072] The mixture of atomized secondary heavy hydrocarbon feed and pre-lifting medium reacts with the regenerated catalyst, and the reaction products and catalyst continue to move upward and react with the incoming feed oil.

[0073] The reaction products and deactivated catalyst flow out of the booster reactor outlet and enter the separation system;

[0074] The deactivated catalyst after separation is processed by the stripping unit and then regenerated in the regeneration reactor. The regenerated catalyst is returned to the bottom of the riser for recycling.

[0075] In the application of the catalytic cracking secondary feed heavy hydrocarbon nozzle described in this embodiment, the catalyst is a catalytic cracking catalyst, and the heavy hydrocarbon is a reclaimed feedstock with a molecular weight greater than 180, rather than a catalytic cracking feedstock oil, such as heavy diesel oil.

[0076] The working process of the catalytic cracking secondary feed nozzle provided in this embodiment of the invention is as follows: Figure 3 As shown, secondary feed heavy hydrocarbons (diesel feedstock) are injected through a pre-lifting medium (steam) pipeline and carried by the pre-lifting medium to the secondary heavy hydrocarbon feed nozzle. After passing through the inlet contraction section 11, throat section 12, secondary mixing section 13, secondary throat section 14, and outlet secondary atomization section 15, the pre-lifting medium (steam) and secondary feed heavy hydrocarbons (diesel) are fully mixed and atomized. The mixture is sprayed into the pre-lifting section of the riser and reacts with the regenerated catalyst from the regenerator, generating a large number of carbocations. These carbocations move upward with the catalyst and enter the feed mixing section of the riser. The catalyst, carbocations, and heavy feedstock oil introduced by the feed nozzle react with each other. The carbocations accelerate the conversion of heavy oil to light oil, increasing the yield of light products. The deactivated catalyst and products continue to move upward to the oil-catalyst separation section at the riser outlet. After stripping, the catalyst enters the regenerator for coking and regeneration, and then returns to the bottom of the pre-lifting section of the riser for recycling.

[0077] In summary, by installing the secondary heavy hydrocarbon feed nozzle at the outlet of the pre-lifting medium pipeline, it avoids the need to drill additional holes on the riser reactor to install the nozzle, thus reducing the difficulty of industrial modification and expanding the applicability of the device.

[0078] By employing a certain proportion of secondary "contraction-expansion" structure, the mixing and atomization of secondary heavy hydrocarbon feed and pre-lifting medium can be further enhanced on the basis of primary atomization. This is beneficial for the contact between the secondary heavy hydrocarbon feed and the catalyst. In the "contraction-expansion" structure, the role of the contraction section is to enhance the mixing of secondary heavy hydrocarbon feed and pre-lifting medium. During the intense mixing process, the pre-lifting medium impacts and breaks up the secondary heavy hydrocarbon feed. The role of the expansion section is to effectively extend and thin the liquid film of the secondary heavy hydrocarbon feed in the sidewall region. Through secondary "contraction-expansion", the atomization effect is further enhanced.

[0079] Because of the bypass channel, the pressure difference between the inside and outside of the nozzle can be automatically balanced. Due to the large molecular weight of the heavy hydrocarbon secondary feed, the large number of atomized diesel droplets at the nozzle outlet come into contact with the hot catalyst, causing a surge in volumetric flow rate due to vaporization. Theoretically, volumetric flow rate is positively correlated with velocity by the first power, while pressure drop is positively correlated with velocity by the square. This means that a surge in volumetric flow rate can easily lead to a large pressure gradient, affecting the stable operation of the nozzle. The bypass channel's function is to regulate the pressure drop before and after the nozzle, making the pressure drop along the process more stable, and thus reducing nozzle pressure drop and energy consumption.

[0080] The catalytic cracking secondary feed nozzle provided by this invention does not require opening holes in the riser wall to install the nozzle with a sleeve. It has a simple structure, is convenient for industrial application, has low energy consumption, and good operational flexibility.

[0081] The catalytic cracking secondary reprocessing heavy hydrocarbon feed nozzle and application method provided by this invention enable the injection of secondary reprocessing heavy hydrocarbons such as diesel into the riser without the need for additional openings in the riser wall for nozzle mounting sleeves. The nozzle's "secondary contraction-expansion combined bypass channel" structure enhances the mixing and atomization of the secondary heavy hydrocarbon feed with the pre-rise medium, balances the pressure difference during secondary heavy hydrocarbon vaporization, and reduces pressure drop. It also allows the secondary heavy hydrocarbon feed to quickly reach the center of the riser, covering the entire cross-section. The nozzle is positioned upstream of the feedstock nozzle in the pre-rise section of the riser. The secondary heavy hydrocarbon feed ejected from the nozzle preferentially contacts and reacts with the catalyst, generating a large number of carbon ions, accelerating feedstock conversion. Therefore, this invention has the effect of increasing the production of light oil products and regulating product distribution.

[0082] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments for application in other fields. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A secondary feed nozzle for catalytic cracking, characterized in that: The nozzle includes: The nozzle consists of an inlet constriction section, a throat section, a secondary mixing section, a secondary throat section, an outlet secondary atomization section, and a bypass channel that runs through the nozzle inlet and outlet. The inlet contraction section, throat section, secondary mixing section, secondary throat section, and outlet secondary atomization section are connected in sequence. The inlet shrinkage section, the secondary mixing section, and the outlet secondary atomization section are connected to the bypass channel; The length ratio range of each part of the inlet contraction section, throat section, secondary mixing section, secondary throat section and outlet secondary atomization section is I1:I2:(I3+I4+I5):I6:I7=(4-5):(3-4):(7-9):(1-2):(3-4); among which, the length ratio range of the upstream conical structure, the middle cylindrical structure and the downstream conical structure in the secondary mixing section is I3:I4:I5=(3-4):1:(3-4); The bypass channel has branches that connect to the secondary mixing section and the outlet secondary atomization section, respectively; The number of bypass channels is two or more, and they are arranged symmetrically. The secondary mixing section is a spindle-shaped structure with conical ends and a cylindrical middle section, with a front cone apex angle of 80°-90° and a rear cone apex angle of 80°-90°. The outlet secondary atomization section has a conical structure with a cone apex angle of 80°-90°; I1: Length of the inlet contraction section; I2: Length of the larynx; I3: Length of the upstream conical structure of the secondary mixing section; I4: Length of the intermediate cylindrical structure in the secondary mixing section; I5: Length of the downstream conical structure of the secondary mixing section; I6: Length of the secondary laryngeal segment; I7: Length of the secondary atomization section.

2. The catalytic cracking secondary feed nozzle according to claim 1, characterized in that: The inlet constriction section has a conical structure with a cone apex angle of 80°-90°; the throat section has a cylindrical structure.

3. The catalytic cracking secondary feed nozzle according to claim 1, characterized in that: The secondary throat segment is a cylindrical structure.

4. A catalytic cracking riser device equipped with a catalytic cracking secondary feed nozzle as described in any one of claims 1-3, characterized in that: The catalytic cracking riser unit includes: a riser feed mixing section and a riser pre-rise section connected in sequence, and also includes a pre-rise medium pipeline. The pre-rise medium pipeline is located in the riser pre-rise section. A gas distributor is also provided in the riser pre-rise section. A regeneration inclined pipe is connected to the outside of the riser pre-rise section. A raw material feed pipe is connected to the outside of the riser feed mixing section. The pre-lifting medium pipeline is provided with a secondary feed inlet, and the secondary feed nozzle is located at the outlet of the pre-lifting medium pipeline.

5. A catalytic cracking method using the catalytic cracking riser unit as described in claim 4, characterized in that: Includes the following steps: Secondary heavy hydrocarbon feed enters from the pre-lifting medium pipeline and moves with the pre-lifting medium to the nozzle; The nozzle mixes and atomizes the secondary heavy hydrocarbon feed with the pre-lifting medium before spraying it out. The mixture of the ejected secondary heavy hydrocarbon feed and the pre-lifting medium reacts with the regenerated catalyst, and the reaction products and catalyst continue to move upward and react with the incoming feed oil. The reaction products and deactivated catalyst flow out of the riser reactor outlet and enter the separation system; The deactivated catalyst after separation is processed by the stripping unit and then regenerated in the regeneration reactor. The regenerated catalyst is returned to the bottom of the riser for recycling.

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