Catalytic cracking secondary light hydrocarbon feed nozzle and method of use thereof

Abstract

This invention provides a catalytic cracking secondary light hydrocarbon feed nozzle and its application method. The catalytic cracking secondary light hydrocarbon feed nozzle includes: an inlet contraction section, a throat section, a mixing expansion section, a mixing chamber, an outlet contraction section, and a branch outlet; the inlet contraction section, throat section, mixing expansion section, mixing chamber, and outlet contraction section are sequentially connected; the mixing chamber, outlet contraction section, and branch outlet are connected. Based on the existing catalytic cracking riser reactor device, this invention eliminates the need for nozzle installation sleeves with openings in the riser wall, providing a convenient industrial modification and application method for catalytic cracking secondary light hydrocarbon feed nozzles and their application. It ensures normal fluidization and transport of catalyst particles in the pre-rise section; it does not generate excessive pressure drop; it has a simple structure, is easy to use, and has good operational flexibility; at the same time, this nozzle also eliminates the safety hazard of traditional atomizing nozzle installation methods that inevitably "span two layers of metal pipe walls".

Description

Technical Field

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

[0002] Existing technologies include patents related to catalytic cracking processes in the oil refining industry. For example, Chinese patent 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 is 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. The steam orifice plate has multiple steam nozzles distributed circumferentially, and the nozzle head has multiple nozzle outlets distributed circumferentially. The nozzle outlet structure is designed as a throat type, consisting of a contraction section, a throat section, and an expansion section. This structure allows for third-stage atomization of the feedstock oil, while simultaneously creating a deceleration zone in the expansion section, effectively solving the problem of excessively high feedstock droplet injection velocity causing severe catalyst breakage. However, this technology has the following drawbacks: it was not specifically developed for secondary light hydrocarbon feed. Its structural characteristics dictate that this type of nozzle can only be installed by inserting a sleeve through an opening in the riser wall, requiring the nozzle or nozzle sleeve to span two layers of metal pipe wall. This installation method cannot guarantee the safe and effective introduction of secondary light hydrocarbon feed, especially considering that many industrial plants currently use a "bottom expansion + center pipe" structure for the bottom pre-lift section, which still falls under the category of traditional nozzle structures. Furthermore, if the nozzle design described in the comparative document is used, the secondary feed cannot quickly reach the center of the riser to cover the entire cross-section, and it cannot solve the problems of rapid vaporization of light hydrocarbons leading to a surge in volumetric flow rate, a large pressure gradient, and operational instability.

[0003] 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 spaced circumferentially. A cyclone separator is installed between the primary steam inner channel and the feed oil channel. The secondary steam orifices are evenly spaced 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 spaced circumferentially on its end face. This technology has the following drawback: it is not specifically developed for secondary light hydrocarbon feedstocks. Its structural characteristics dictate that this type of nozzle can only be installed by setting a sleeve through an opening in the riser wall, and the nozzle or nozzle sleeve must span two layers of metal pipe wall. This installation method cannot guarantee the safe and effective introduction of secondary feed light hydrocarbons, especially since many industrial plants currently use a "bottom expansion + central pipe" structure for the bottom pre-lift section, which still falls under the category of traditional nozzle structures. Furthermore, if the nozzle type described in the comparative document is used, the secondary feed also cannot quickly reach the center of the riser to cover the entire cross-section, and it also cannot solve the problems of rapid vaporization of light hydrocarbons leading to a surge in volumetric flow rate, a large pressure gradient, and operational instability.

[0004] Furthermore, in recent years, feed atomizing nozzles used in catalytic cracking units have not been specifically developed for secondary feed; their sole optimization goal is atomization effect. Domestic feed atomizing nozzles mainly include: CS type (ZL200410010045.3, ZL201210336614.8, ZL201210336937.7) which uses secondary atomizing steam, non-uniform atomization, and a steam curtain; LPC type (ZL90209410.6, ZL201610476268.1) with a throat tube (i.e., composed of a contraction section + throat section + expansion section and its deformation); KH type (ZL89207961.9, ZL200420066089.3) with a supersonic atomizing steam throat tube; and BWJ type (ZL98233035.9) with a swirl structure. There are various types of nozzles, including the UPC-ɑ type (ZL00109776.8) and ZL200620130509.9 with a porous steam distributor; the CCK type (ZL99219391.5) with a combination of secondary atomized steam and a Venturi (throat) structure; and the ZL201620539374.5 with a "secondary atomized steam + Venturi + swirl structure". Foreign nozzles mainly include the target nozzle from S&W, the multi-hole Optimix nozzle with a built-in porous steam distributor developed by UOP, the ATOMAX nozzle with a built-in porous steam distributor and baffle jointly developed by Mobile and Kellogg, the feed nozzle with a nozzle cap developed by ABB Lummus that can form a flat jet, and the nozzle with secondary atomized steam developed by Exxon.

[0005] In summary, these nozzles aim to reduce atomized particle size, employing either single / double Venturi (throat) nozzles or swirling structures to achieve liquid film stretching and thinning, or using secondary atomized steam to repeatedly impact and break up the raw materials. However, the structural characteristics of these nozzles dictate that they can only be installed by setting up a sleeve through an opening in the riser wall. This installation method cannot guarantee the safe and effective introduction of secondary feed light hydrocarbons. In particular, for the aforementioned bottom pre-lift section with a "bottom expansion + central tube" structure, it still falls into the category of traditional nozzle structures. In other words, these nozzles cannot solve the problems mentioned above, such as spanning two layers of metal pipe walls, the inability of recycled light hydrocarbons to quickly reach the center of the riser, the surge in light hydrocarbon gasification volume flow leading to a larger pressure gradient, and operational instability.

[0006] However, 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 differs from that of the pre-lifting medium by more than 200 times. This could cause severe impact and breakage of the catalyst in the pre-lifting section due to excessively high local density. Summary of the Invention

[0007] To address the shortcomings of the existing technology, this invention, based on the existing catalytic cracking riser reactor device, eliminates the need for nozzle mounting sleeves with openings in the riser wall. It provides a convenient industrial modification and application of a catalytic cracking secondary light hydrocarbon feed nozzle and its application, ensuring normal fluidization and transport of catalyst particles in the pre-lifting section; it does not generate excessive pressure drop, has a simple structure, is easy to use, and has good operational flexibility; at the same time, this nozzle also eliminates the safety hazard of the traditional atomizing nozzle installation method that inevitably "spans two layers of metal pipe walls".

[0008] To achieve the above objectives, the present invention provides a catalytic cracking secondary light hydrocarbon feed nozzle, the nozzle comprising:

[0009] Inlet constriction section, throat section, mixing expansion section, mixing chamber, outlet constriction section, and branch outlet;

[0010] The inlet constriction section, throat section, mixing expansion section, mixing chamber, and outlet constriction section are connected in sequence.

[0011] The mixing chamber, the outlet contraction section, and the branch outlet are connected.

[0012] In some embodiments, the branch outlet angle is variable, and the number is greater than or equal to one; and the branch outlet penetrates the nozzle sidewall and the mixing chamber.

[0013] In some embodiments, the inlet constriction section is a conical structure with a cone apex angle of 70°-90°; the throat section is a cylindrical structure.

[0014] In some embodiments, the hybrid expansion section is a conical structure with a cone apex angle of 70°-80°.

[0015] In some embodiments, the mixing cavity is a cylindrical structure.

[0016] In some embodiments, the outlet contraction section is a conical structure with a cone apex angle of 50°-60°.

[0017] In some embodiments, there are two branch outlets, designated as a first branch outlet and a second branch outlet; the first branch outlet and the second branch outlet are cylindrical structures, with an angle of 30°-40° between them and the axis of the mixing chamber along the nozzle outlet direction, and 4-6 outlets are evenly distributed along the circumference of the outer wall of the nozzle.

[0018] In some embodiments, the length ratio of each part of the inlet constriction section, throat section, mixing expansion section, mixing cavity and outlet constriction section is I1:I2:I3:I4:I5 = (2-3):(1-2):1:(3-4):(1.5-2.5).

[0019] The present invention also provides an application of the above-described catalytic cracking secondary light hydrocarbon feed nozzle to a matching catalytic cracking riser device, characterized in that: the catalytic cracking riser device includes: a riser feed mixing section and a riser pre-lifting section connected in sequence, and further includes a pre-lifting medium pipeline, the pre-lifting pipeline being disposed within the riser pre-lifting section, the riser pre-lifting section also being provided with a gas distributor, the riser pre-lifting section being externally connected to a regeneration inclined pipe, and the riser feed mixing section being externally connected to a raw material feed pipe;

[0020] The pre-lifting medium pipeline is provided with a secondary feed inlet, and the secondary light hydrocarbon feed nozzle is located at the outlet of the pre-lifting medium pipeline of the lifting pipe.

[0021] The present invention also provides a method for applying a catalytic cracking secondary light hydrocarbon feed nozzle to a matching catalytic cracking riser unit, comprising the following steps:

[0022] The secondary light hydrocarbon feed enters from the pre-lifting medium pipeline and moves with the pre-lifting medium to the nozzle;

[0023] Inside the nozzle, the pre-lifting medium crushes and atomizes the secondary light hydrocarbon feed, and the pre-lifting medium and the secondary feed are mixed and atomized before being sprayed out. The nozzle has the dual functions of conveying the pre-lifting medium and atomizing / conveying the secondary feed, ensuring the normal fluidization of catalyst particles in the pre-lifting section while achieving efficient atomization of the light hydrocarbons in the secondary feed.

[0024] The mixture of atomized secondary light 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.

[0025] The reaction products and deactivated catalyst flow out of the riser reactor outlet and enter the separation system;

[0026] 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.

[0027] Compared with the prior art, the present invention has the following advantages:

[0028] By installing the secondary light hydrocarbon feed nozzle at the outlet of the pre-lifting medium pipeline, it avoids the need to drill additional holes on the lifting pipe device to install the nozzle, thus reducing the difficulty of industrial modification; it also eliminates the safety hazards of traditional atomizing nozzle installation methods, has a simple structure, is convenient for industrial modification and application, has low energy consumption, and good operational flexibility.

[0029] By employing a structure with a certain ratio of "contraction-expansion-mixing-recontraction-branch outlet," the mixing and atomization of the secondary feed light hydrocarbons and the pre-lifting medium can be enhanced, which is beneficial to the contact between the secondary feed and the catalyst. The "contraction-expansion-mixing-recontraction" structure and the downstream multi-branch outlet work together and are indispensable. The contraction-throat-expansion section not only has the effect of liquid film stretching and thinning, but its suction effect also helps to increase the nozzle flow rate. While the downstream mixing chamber and outlet contraction section enhance the atomization effect, the porous branch structure connected to them "compensates" for the flow loss caused by the atomization process, maintains the high flow rate generated by the suction of the upstream contraction-throat-expansion section, and keeps the flow coefficient in a high range.

[0030] Multi-branch outlets can effectively increase nozzle flow rate and reduce nozzle pressure drop. On the other hand, since the molecular weight of light hydrocarbon feedstock is not large, its viscosity and density are also lower than those of feedstocks such as diesel and feed oil, which are more difficult to atomize. However, for light hydrocarbons, the flow rate of pre-lifting medium / atomizing medium allowed by the process is usually low. Multi-branch outlets, due to the higher velocity of light hydrocarbons and pre-lifting medium inside, can enhance the atomization of light hydrocarbons and promote the uniform distribution of the pre-lifting mixed phase in the pre-lifter. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying 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.

[0032] Figure 1 This is a cross-sectional view of the catalytic cracking secondary light hydrocarbon feed nozzle shown in an embodiment of the present invention;

[0033] Figure 2 This is a top view of the catalytic cracking secondary light hydrocarbon feed nozzle shown in an embodiment of the present invention;

[0034] Figure 3 This is a schematic diagram of the industrial application of the catalytic cracking secondary light hydrocarbon feed nozzle shown in an embodiment of the present invention;

[0035] Figure 4 This illustrates the effect of the angle of the multi-branch outlet structure on the atomized particle size in this embodiment of the invention.

[0036] in:

[0037] 1-Secondary light hydrocarbon feed nozzle;

[0038] 11-Imported contraction segment;

[0039] 12-Laryngeal segment;

[0040] 13-Mixed expansion segment;

[0041] 14-Mixing chamber;

[0042] 15 - Export contraction section;

[0043] 16 - First branch exit;

[0044] 17 - Second branch exit;

[0045] 2- Feed mixing section via riser;

[0046] 3-Pre-lifting section of the riser pipe;

[0047] 4-Boosting medium pipeline;

[0048] 41 - Secondary feed inlet;

[0049] 5-Gas distributor;

[0050] 6-Regeneration inclined tube;

[0051] 7-Raw material feed pipe;

[0052] I 1 - Length of the inlet contraction section;

[0053] I 2 - Length of the larynx segment;

[0054] I 3 - Length of the mixed expansion segment;

[0055] I4 - Mixing chamber length;

[0056] I5 - Length of the exit contraction section. Detailed Implementation

[0057] 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.

[0058] 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.

[0059] 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.

[0060] like Figure 1-2 As shown, this embodiment of the invention provides a catalytic cracking secondary light hydrocarbon feed nozzle 1. The nozzle 1 includes: an inlet constriction section 11, a throat section 12, a mixing expansion section 13, a mixing chamber 14, an outlet constriction section 15, and a branch outlet. In this embodiment, the number of branch outlets can be set to two, for example, a first branch outlet 16 and a second branch outlet 17. The inlet constriction section 11, the throat section 12, the mixing expansion section 13, the mixing chamber 14, and the outlet constriction section 15 are connected in sequence. The mixing chamber 14, the outlet constriction section 15, the first branch outlet 16, and the second branch outlet 17 are connected in sequence.

[0061] The branch outlet angle is variable, and the number is greater than or equal to one; and the branch outlet penetrates the nozzle sidewall and the mixing chamber.

[0062] Specifically, the inlet contraction section 11 has a conical structure with a cone apex angle of 70°-90°; the throat section 12 has a cylindrical structure; the mixing expansion section 13 has a conical structure with a cone apex angle of 70°-80°; the mixing chamber 14 has a cylindrical structure; and the outlet contraction section 15 has a conical structure with a cone apex angle of 50°-60°.

[0063] The branch outlets are of two types, designated as the first branch outlet 16 and the second branch outlet 17. The first branch outlet 16 and the second branch outlet 17 are cylindrical structures, forming an angle of 30°-40° with the axis of the mixing chamber 14 along the nozzle outlet direction, and are evenly distributed in 4-6 locations along the circumference of the nozzle outer wall. The length ratio of each part of the inlet contraction section 11, throat section 12, mixing expansion section 13, mixing chamber 14, and outlet contraction section 15 is I1:I2:I3:I4:I5 = (2-3):(1-2):1:(3-4):(1.5-2.5).

[0064] Another embodiment of the present invention provides a method for applying the catalytic cracking secondary light hydrocarbon 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.

[0065] 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.

[0066] Furthermore, another embodiment of the present invention provides a method for applying a catalytic cracking secondary light hydrocarbon feed nozzle to a matching catalytic cracking riser unit, comprising the following steps:

[0067] The secondary light hydrocarbon feed enters from the pre-lifting medium pipeline and moves with the pre-lifting medium to the nozzle;

[0068] Inside the nozzle, the pre-lifting medium crushes and atomizes the secondary light hydrocarbon feed, and the pre-lifting medium and the secondary feed are mixed and atomized before being sprayed out. The nozzle has the dual functions of conveying the pre-lifting medium and atomizing / conveying the secondary feed, ensuring the normal fluidization of catalyst particles in the pre-lifting section while achieving efficient atomization of the light hydrocarbons in the secondary feed.

[0069] The mixture of atomized secondary light 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.

[0070] The reaction products and deactivated catalyst flow out of the riser reactor outlet and enter the separation system;

[0071] 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.

[0072] Specifically, the working process of the catalytic cracking secondary light hydrocarbon feed nozzle provided in this embodiment of the invention is as follows: as shown in the attached figure. Figure 3As shown, the nozzle is located at the outlet of the pre-lifting medium pipeline in the riser. Secondary feed light hydrocarbons (gasoline) are injected through the pre-lifting medium (steam + dry gas) pipeline and carried by the pre-lifting medium to the secondary light hydrocarbon feed nozzle. The hydrocarbons then pass through the inlet contraction section 11, throat section 12, mixing expansion section 13, mixing chamber 14, outlet contraction section 15, first branch outlet 16, and second branch outlet 17. Within the nozzle, the pre-lifting medium and secondary feed light hydrocarbons are thoroughly mixed, and the secondary feed light hydrocarbons are atomized and sprayed out together. The "contraction-expansion-mixing-recontraction" structure in the inlet contraction section 11, throat section 12, and mixing expansion section 13 works synergistically with the multi-branch outlets 16 and 17 downstream, located in the mixing chamber 14 and outlet contraction section 15; none of these can be omitted. The contraction-throat-expansion section not only has a liquid film stretching-thinning effect, but its suction effect also helps to increase the nozzle flow rate. Meanwhile, the downstream mixing chamber and outlet contraction section, while enhancing the atomization effect, have a porous branch structure connected to them that "compensates" for the flow loss caused by the atomization process, maintaining the high flow rate generated by the suction of the upstream contraction-throat-expansion section and keeping the flow coefficient within a high range. Because the diameter of the porous branch outlet is significantly smaller than that of the outlet contraction section, the velocity of light hydrocarbons and pre-lifted media is higher within it, which can enhance the atomization of light hydrocarbons and promote the uniform distribution of the pre-lifted mixed phase within the pre-lifter.

[0073] The pre-lifting medium ejected from the outlet contraction section and porous branch structure, together with the secondary light hydrocarbon feed, also performs the function of the pre-lifting medium in the traditional riser pre-lifting section, ensuring normal fluidization and transport of catalyst particles within the pre-lifting section. The mixture is injected into the riser pre-lifting section and reacts with the regenerated catalyst from the regenerator, generating a large number of carbocations. These carbocations move upwards with the catalyst and enter the riser feed mixing section. The catalyst, carbocations, and incoming heavy feed oil mix and react, with the carbocations accelerating the conversion of heavy oil to light oil and increasing the yield of light products. The deactivated catalyst and products continue to move upwards to the riser outlet oil-catalyst separation section. After stripping, the catalyst enters the regenerator for coking and regeneration, then returns to the bottom of the riser pre-lifting section for recycling.

[0074] Furthermore, in the embodiments of the present invention, the angle between the multi-branch outlet and the axis has a significant impact on the atomized particle size. A comparison of the atomized particle sizes obtained under different angle conditions is shown in the attached figure. Figure 4 As shown, the angle of the multi-branch outlet has a significant effect on the atomized particle size. In this embodiment, the preferred angle is 30°.

[0075] In summary, the catalytic cracking secondary refining light hydrocarbon feed nozzle and application method provided by this invention achieve the injection of secondary refining light hydrocarbons such as gasoline into the riser without the need for additional openings in the riser wall for nozzle installation sleeves. The nozzle's "contraction-expansion-mixing-recontraction-branch outlet" structure enhances the mixing and atomization of the secondary feed and pre-lifting medium, and increases the nozzle flow rate; it allows the secondary light hydrocarbon feed to quickly reach the center of the riser, promoting the uniform distribution of the pre-lifted mixed phase within the pre-lifter. The nozzle is positioned upstream of the feedstock nozzle in the pre-lifting section of the riser, where it preferentially contacts and reacts with the catalyst, generating a large number of carbon ions and accelerating the conversion of light hydrocarbons. This gives the invention the characteristic of increasing the production of light oil products; it also eliminates the safety hazards of traditional atomizing nozzle installation methods.

[0076] This invention, based on existing catalytic cracking riser reactor devices, eliminates the need for nozzle mounting sleeves with openings in the riser wall, providing a convenient industrial modification and application for a secondary light hydrocarbon feed nozzle and its application. Inside this nozzle, the mixing of the pre-lifting medium and the secondary light hydrocarbon feed is enhanced, and the pre-lifting medium crushes and atomizes the secondary light hydrocarbon feed. After mixing and atomization, the pre-lifting medium and the secondary feed are sprayed out. At this point, both also jointly perform the function of the pre-lifting medium in the traditional riser pre-lifting section, ensuring normal fluidization and transport of catalyst particles within the pre-lifting section; it does not generate excessive pressure drop, has a simple structure, is easy to use, and has good operational flexibility. Simultaneously, this nozzle eliminates the safety hazard of the traditional atomizing nozzle installation method that inevitably "spans two layers of metal pipe wall."

[0077] By installing the secondary light hydrocarbon feed nozzle at the outlet of the pre-lifting medium pipeline, the need to drill additional holes on the lifting pipe device to install the nozzle is avoided, reducing the difficulty of industrial modification; it also eliminates the safety hazards of traditional atomizing nozzle installation methods and expands the scope of application of the present invention.

[0078] The adoption of a specific "contraction-expansion-mixing-recontraction-branch outlet" structure enhances the mixing and atomization of the secondary feed light hydrocarbons and the pre-lifting medium, facilitating contact between the secondary feed and the catalyst. The "contraction-expansion-mixing-recontraction" structure and the downstream multi-branch outlet work synergistically, and neither can be dispensed with. The contraction-throat-expansion section not only has a liquid film stretching and thinning effect, but its suction effect also helps to increase the nozzle flow rate. Meanwhile, the downstream mixing chamber and outlet contraction section, while enhancing the atomization effect, are connected to a porous branch structure that "compensates" for the flow losses caused by the atomization process, maintaining the high flow rate generated by the suction of the upstream contraction-throat-expansion section and keeping the flow coefficient within a high range.

[0079] Multi-branch outlets can effectively increase nozzle flow rate and reduce nozzle pressure drop. On the other hand, since light hydrocarbon feedstocks have low molecular weight, their viscosity and density are also lower than those of feedstocks such as diesel and feed oil, which are more difficult to atomize. However, for light hydrocarbons, the flow rate of the pre-lifting medium / atomizing medium allowed by the process is usually low. Multi-branch outlets, due to the higher velocity of light hydrocarbons and pre-lifting medium inside, can enhance the atomization of light hydrocarbons and promote the uniform distribution of the pre-lifting mixed phase in the pre-lifter.

[0080] The catalytic cracking secondary light hydrocarbon feed nozzle and its application described in this invention do not require opening holes in the riser wall to install the nozzle with a sleeve. The structure is simple, easy to apply in industrial transformation, has low energy consumption, and good operational flexibility.

[0081] 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 catalytic cracking riser apparatus, fitted with a catalytic cracking secondary light hydrocarbon feed nozzle, 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 light hydrocarbon inlet, and the secondary light hydrocarbon inlet nozzle is located at the outlet of the pre-lifting medium pipeline. The catalytic cracking secondary light hydrocarbon feed nozzle includes: Inlet constriction section, throat section, mixing expansion section, mixing chamber, outlet constriction section, and branch outlet; The inlet constriction section, throat section, mixing expansion section, mixing chamber, and outlet constriction section are connected in sequence. The mixing chamber, the outlet contraction section, and the branch outlet are connected; Furthermore, the branch outlet penetrates the nozzle sidewall and communicates with the mixing chamber; The length ratio of each part of the structure, including the inlet constriction section, throat section, mixing expansion section, mixing chamber, and outlet constriction section, is I1:I2:I3:I4:I5 = (2-3):(1-2):1:(3-4):(1.5-2.5); I1: Length of the inlet contraction section; I2: Length of the larynx; I3: Length of the mixed expansion segment; I4: Mixing chamber length; I5: Length of the exit contraction section; The branch outlet is divided into a first branch outlet and a second branch outlet; the first branch outlet and the second branch outlet are cylindrical structures, and the angle between each branch outlet and the axis of the mixing chamber along the nozzle outlet direction is 30°. The first branch outlet and the second branch outlet are evenly distributed in 4-6 circumferentially along the outer wall of the nozzle.

2. The catalytic cracking riser unit according to claim 1, characterized in that: The inlet contraction section has a conical structure with a cone apex angle of 70°-90°; the throat section has a cylindrical structure.

3. The catalytic cracking riser unit according to claim 1, characterized in that: The hybrid expansion section has a conical structure with a cone apex angle of 70°-80°.

4. The catalytic cracking riser unit according to claim 1, characterized in that: The mixing chamber has a cylindrical structure.

5. The catalytic cracking riser unit according to claim 1, characterized in that: The outlet contraction section has a conical structure with a cone apex angle of 50°-60°.

6. A catalytic cracking method using a catalytic cracking riser unit as described in any one of claims 1-5, characterized in that: Includes the following steps: The secondary light hydrocarbon feed enters from the pre-lifting medium pipeline and moves with the pre-lifting medium to the nozzle; Inside the nozzle, the pre-lifting medium crushes and atomizes the secondary light hydrocarbon feed. After the pre-lifting medium and the secondary light hydrocarbon feed are mixed and atomized, they are sprayed out. The nozzle has the dual function of conveying the pre-lifting medium and atomizing / conveying the secondary light hydrocarbon feed, ensuring the normal fluidization of catalyst particles in the pre-lifting section while atomizing the light hydrocarbons of the secondary feed. The mixture of the sprayed secondary light 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.

Images