Apparatus and method for catalytic cracking

Abstract

The application relates to the field of catalysis technology and discloses a device and a method for catalytic cracking. The device comprises a multistage reaction unit and a cracking reaction unit, the multistage reaction unit comprises a multivariable-diameter riser and a multistage reaction settler, and the cracking reaction unit comprises a cracking riser and a cracking settler; the multivariable-diameter riser comprises a first reaction zone, a second reaction zone and a third reaction zone which are sequentially connected in the length direction of the multivariable-diameter riser, the inner diameter of the second reaction zone is larger than that of the first reaction zone and the third reaction zone, and an inner conveying pipe extending to the inside of the second reaction zone is arranged at the connection position of the third reaction zone and the second reaction zone; the cracking settler comprises a cracking stripping section, a turbulent reaction section and a cracking settling section which are sequentially arranged in the length direction of the cracking settler, the outlet of the cracking riser is located in the turbulent reaction section, and the cracking stripping section is provided with a cracking catalyst outlet communicated with the second reaction zone. The device can improve the reaction efficiency of catalytic cracking of heavy oil and light hydrocarbon and realize the close coupling of heavy oil and light hydrocarbon.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of catalysis, in particular, to a device and method for catalytic cracking. BACKGROUND

[0002] Early catalytic cracking reaction used aluminum silicate beads as catalyst, and the reactor used a dense bed reactor. With the emergence of high-activity and high-selectivity zeolite catalysts, the reaction rate of petroleum hydrocarbons with the catalysts was greatly accelerated, and the reactor used a fast conveying bed riser, which was conducive to improving the liquid product yield and selectivity. The riser reactor has made great progress in structure and operation mode compared with the dense bed reactor, mainly in the mixing of oil gas and catalyst in the feed section, the rapid separation of outlet products, the reduction of temperature gradient on the riser cross section, and the reduction of return, etc. Due to the high activity of zeolite catalysts, which greatly improves the reaction intensity, since the 1960s-1970s, many companies have developed their own fast conveying bed reactors, i.e. riser reactors, which have good flexibility and flexibility, emphasize the primary cracking of heavy oil, and the light oil yield and selectivity are ideal. This type of reactor still has strong vitality to this day. Since the end of the last century, the CNIII gasoline standard has begun to limit the olefin content of gasoline, CN1237477A, CN1245202A, CN1232069A, etc. proposed a variable-diameter riser, which increases a section of the expansion in the middle of the riser, thereby forming a fluidized bed reaction section, and further strengthening the secondary reaction of the generated gasoline. Research has found that such reactors can crack heavy oil at the same time while taking into account the secondary conversion of gasoline.

[0003] The initial variable-diameter riser technology does not consider the need for internal components between the riser section and the fluidized bed section to adjust the gas-solid fluidization state. Since the size of the industrial device is meter-level, without internal components, due to factors such as the high-speed fluid jet of the lower riser into the expansion section, it is difficult to form a stable fluidization of gas-solid fluid in the lower part of the expansion section and further form a stable dense phase region of solid particles. Although during the industrial implementation of the variable-diameter riser, arched (convex) distribution plates, special-shaped (basin-shaped) distribution plates, concave distribution plates, and mushroom head distributors have been successively introduced, which can form a fully uniform and stable fluidization of the high-speed oil gas and catalysts coming out of the riser, and part of the catalysts form a stable fluidized bed; however, the expansion section of the riser is generally connected to the upper riser through a tapered round cone-shaped outer cylinder, and no internal components are installed in this section to adjust the gas-solid fluidization.

[0004] In order to improve the quality of gasoline, reduce the olefin content of gasoline and increase the yield of cracking gas, a large number of technical measures for light hydrocarbon recycling are disclosed at home and abroad, and there are two typical ways: the first way is to recycle gasoline or other light hydrocarbons to the original heavy oil riser, which is generally injected into the upstream of the feed oil nozzle, for example, US 5043522A and US 5846403A disclose that the catalytic cracking gasoline is injected into the upstream of the feed oil nozzle, and the catalytic conversion is carried out by using the high-temperature and high-activity regenerated catalyst; CN1160746A also discloses a method for injecting low-quality gasoline such as straight-run gasoline and coking gasoline into the lower part of the riser reactor to make it contact with the regenerated catalyst preferentially; the second way is to use a separate gasoline or light hydrocarbon riser for recycling, for example, CN1069054A and US3784463A both use a double-riser reactor for reaction, and low-quality gasoline including catalytic cracking gasoline is injected into the gasoline riser reactor to realize catalytic upgrading of the low-quality gasoline by using high-temperature and large catalyst / oil ratio reaction conditions, so as to improve the yield of liquefied gas and the octane number of gasoline; the molecules generated after the light hydrocarbon feedstock contacts with the catalyst are relatively small, and the volume expansion is obvious, which has an impact on the heavy oil feedstock in the upper part of the catalytic cracking riser reactor and the contact between the heavy oil and the catalyst. Among them, the first way has a lower proportion of light hydrocarbon recycling to maintain the negative impact of heavy oil reaction; the second way adds a separate light hydrocarbon riser based on the traditional single-riser reactor, so that the light hydrocarbon can be subjected to secondary cracking reaction, and the different raw materials can be independently optimized, but the traditional riser is not ideal for controlling the reaction depth, for example, if the outlet temperature of the riser is increased to achieve a higher conversion depth, over-cracking reaction is easy to occur; if the outlet reaction temperature of the riser is low, the ideal conversion depth cannot be achieved.

[0005] In addition, "Analysis of the Application of Catalytic Cracking DCC Double-Riser Process (DCC plus)" reports the characteristics of the catalytic cracking DCC double-riser process (DCC plus), the heavy oil reactor includes a riser and a turbulent bed, and the oil gas and catalyst at the end of the light hydrocarbon riser are injected into the main settler; "Analysis of the Operation of the Catalytic Cracking Device of the Combination Process of Heavy Oil MIP and Poor Catalytic Cracking Diesel LTAG" discloses the double-reactor process of the combination of the heavy oil MIP reactor and the poor catalytic cracking diesel LTAG reactor. However, there are still defects that the effects of heavy oil and light hydrocarbon cracking reactions are not ideal, and the product properties and product distribution are not easy to flexibly control. SUMMARY

[0006] The purpose of the present application is to provide a catalytic cracking device and method which can strengthen the gas-solid mixing and contact in the heavy oil cracking process and the light hydrocarbon cracking process, improve the catalytic reaction efficiency, realize the close coupling of the heavy oil reactor and the light hydrocarbon reactor, and improve the operation flexibility of controlling the product properties and product distribution.

[0007] The inventor of the present application accidentally found that, in the research of catalytic cracking, after coupling a heavy oil reactor with a light hydrocarbon cracking reactor in parallel by using an expanded diameter riser, the light hydrocarbon cracked catalyst is reused from the outlet of the cracking catalyst to the expanded diameter section of the heavy oil reactor, which not only can independently carry out the heavy oil cracking process and the light hydrocarbon cracking process to improve the recycling ratio of light hydrocarbon, but also helps to strengthen the catalytic reaction of heavy oil; by arranging an inner conveying pipe inside the expanded diameter section of the heavy oil reactor, the gas-solid fluidization state of the expanded diameter section can be changed and optimized, and the adjustment range of the gas linear velocity and the catalyst bed density in the expanded diameter section is widened; and by arranging a turbulent reaction section in the cracking settler of the light hydrocarbon cracking reactor, it is also beneficial to the full intensive contact of the light hydrocarbon with the cracking catalyst in the reaction section, which can realize the efficient contact reaction of the light hydrocarbon with the catalyst at a lower temperature and a low space velocity, and avoid the over-cracking reaction of the light hydrocarbon caused by the too high reaction temperature; at this time, the coupling of the heavy oil reactor and the light hydrocarbon cracking reactor can simultaneously carry out the separate and efficient cracking / cracking operation control of the heavy oil and the light hydrocarbon, has more operation means, and can realize various flexible operations for regulating and controlling the product properties and product distribution.

[0008] In order to achieve the above-mentioned purpose, the first aspect of the present application provides a catalytic cracking device, which comprises a multi-stage reaction unit and a cracking reaction unit, the multi-stage reaction unit comprises a multi-variable diameter riser and a multi-stage reaction settler, and the cracking reaction unit comprises a cracking riser and a cracking settler; the multi-variable diameter riser comprises a first reaction zone, a second reaction zone and a third reaction zone which are sequentially connected in series along the length direction of the multi-variable diameter riser, the outlet of the third reaction zone is communicated with the multi-stage reaction settler, the inner diameter of the second reaction zone is larger than that of the first reaction zone and the third reaction zone, and an inner conveying pipe extending to the inside of the second reaction zone is arranged at the connection between the third reaction zone and the second reaction zone; the cracking settler comprises a cracking stripping section, a turbulent reaction section and a cracking settling section which are sequentially arranged along the length direction of the cracking settler, and the outlet of the cracking riser is located in the turbulent reaction section, and the cracking stripping section is provided with a cracking catalyst outlet communicated with the second reaction zone.

[0009] Preferably, the ratio of the inner conveying pipe to the inner diameter of the third reaction zone is 0.9-1.2:1, and the ratio of the inner conveying pipe to the length of the second reaction zone is 0.15-0.8:1.

[0010] More preferably, the ratio of the inner diameters of the first reaction zone, the second reaction zone and the third reaction zone is 1:2-5:0.7-1.5, and the ratio of the lengths is 1:0.3-2:0.5-2; the ratio of the inner diameters of the turbulent reaction section, the cracking stripping section and the cracking settling section is 1:0.4-0.8:2.5-5, and the ratio of the lengths is 1:1.5-3:1.5-4; and the ratio of the lengths of the multi-variable diameter riser and the cracking riser is 1:0.5-1.2.

[0011] Further preferably, at least one inner conveying hole is arranged on the side wall of the inner conveying pipe, and the distance between the inner conveying hole and the inlet of the third reaction zone is 0.5-2 m.

[0012] Specifically, the ratio of the total area of the at least one inner conveying hole to the cross-sectional area of the inner conveying pipe is 0.05-0.3:1.

[0013] As a preferred embodiment, a distribution inner member is arranged in the second reaction zone and connected with the first reaction zone, and the distribution inner member is provided with a plurality of distribution holes.

[0014] Preferably, the distribution inner member comprises a distribution cylinder connected with the first reaction zone and an end distribution plate connected with the distribution cylinder, and the distribution holes are arranged on the distribution cylinder and the end distribution plate, and the end distribution plate is located at the end of the distribution cylinder away from the first reaction zone.

[0015] More preferably, the ratio of the sum of the areas of the distribution holes on the distribution cylinder to the cross-sectional area of the first reaction zone is 0.6-4:1, and the ratio of the sum of the areas of the distribution holes on the end distribution plate to the vertical projection area of the end distribution plate is 0.1-0.3:1.

[0016] More preferably, a side channel extending to the outside of the distribution cylinder is arranged at the distribution hole on the distribution cylinder, and the opening section of the side channel away from the distribution cylinder is a slope facing the first reaction zone.

[0017] Further preferably, the ratio of the area of the end distribution plate to the cross-sectional area of the second reaction zone is 0.7-0.85:1.

[0018] Specifically, the first reaction zone, the second reaction zone, the third reaction zone and the inner conveying pipe are coaxially arranged, and the outlet of the cracking catalyst is located at the bottom of the cracking stripping section and communicates with the bottom of the second reaction zone.

[0019] More specifically, the multi-diameter riser further comprises a multi-stage reaction pre-lifting section connected with the inlet of the first reaction zone, the cracking riser comprises a cracking pre-lifting section and a cracking reaction section connected in series along the length direction of the cracking riser, the outlet of the cracking reaction section is located at one end of the turbulent reaction section close to the cracking stripping section, the transition section between the multi-stage reaction pre-lifting section and the first reaction zone communicates with a multi-stage reaction feeding unit, and the transition section between the cracking pre-lifting section and the cracking reaction section communicates with a cracking feeding unit.

[0020] Further specifically, a cracking distributor is arranged at the outlet of the cracking reaction section, and the gas phase outlet of the cracking settling section communicates with the multi-stage reaction settler.

[0021] Typically, the device further comprises a regeneration unit, the multi-stage reaction settler is provided with a multi-stage reaction catalyst outlet in communication with an inlet of the regeneration unit, and a regenerated catalyst outlet of the regeneration unit is in communication with the multi-diameter riser and / or the cracking riser.

[0022] The second aspect of the present application provides a method for catalytic cracking, which uses the device described above, and the method comprises the following steps:

[0023] The multi-stage reaction mixture formed by mixing the heavy feedstock with the multi-stage reaction catalyst is input from the inlet of the first reaction zone, sequentially enters the first reaction zone, the second reaction zone, and then enters the third reaction zone from the inner conveying pipe to perform multi-stage catalytic reaction to obtain a multi-stage reaction product, and the multi-stage reaction product is subjected to multi-stage reaction separation by the multi-stage reaction settler to obtain a multi-stage reaction oil and gas product and a multi-stage reaction spent catalyst;

[0024] The cracking mixture formed by mixing the light feedstock with the cracking catalyst is input from the inlet of the cracking riser, and is subjected to cracking catalytic reaction by the cracking riser to obtain a cracking reaction product, which is subjected to turbulent flow reaction after entering the turbulent flow reaction section, and then is subjected to cracking separation by the cracking settler and cracking stripping by the cracking stripping section to obtain a cracking oil and gas product and a cracking spent catalyst;

[0025] The cracking spent catalyst is input from the cracking catalyst outlet to the second reaction zone to mix with the multi-stage reaction mixture.

[0026] Preferably, the inlet temperature of the inner conveying pipe is 510-540°C, and the outlet temperature of the cracking riser is 540-620°C.

[0027] Preferably, the inlet temperature of the inner conveying pipe is 550-640°C, and the outlet temperature of the cracking riser is 560-660°C.

[0028] More preferably, the residence time of the multi-stage reaction mixture in the first reaction zone is 0.8-2s, the residence time in the second reaction zone is 5-15s, and the residence time in the third reaction zone is 0.5-1.5s; the residence time of the cracking mixture in the cracking riser is 0.8-3.5s, and the residence time in the turbulent flow reaction section is 3-13s.

[0029] By the technical scheme, the device for catalytic cracking provided by the application can independently perform heavy oil cracking process and light hydrocarbon cracking process through the parallelly arranged multi-stage reaction unit and cracking reaction unit, improve the recycling ratio of light hydrocarbon, and recycle the catalyst after light hydrocarbon cracking from the cracking catalyst outlet to the second reaction area, which helps to improve the flow and activity of the catalyst in the second reaction area, strengthen the catalytic reaction of heavy oil, and realize the close coupling of the heavy oil cracking process and the light hydrocarbon cracking process; by arranging the inner conveying pipe inside the multi-diameter riser of the multi-stage reaction unit, the gas-solid fluidization state of the second reaction area can be changed and optimized, the adjustment range of the gas linear velocity and the catalyst bed density in the second reaction area is widened, and the turbulent reaction section is arranged in the cracking settler of the cracking reaction unit, the cracking catalyst density of the turbulent reaction section is large, which is beneficial to the full intensive contact of light hydrocarbon with the cracking catalyst in the reaction section, can realize the efficient contact reaction of light hydrocarbon with the catalyst at a low temperature and a low space velocity, and avoid the over-cracking reaction of light hydrocarbon caused by too high reaction temperature; the coupling of the two reaction units in the device provided by the application can simultaneously control the separate cracking / cracking operation of heavy oil and light hydrocarbon, has more operation means, and realizes various flexible operations for regulating and controlling the product properties and product distribution.

[0030] Other advantages of the application and technical effects of the preferred embodiments will be further described in the specific embodiments below. BRIEF DESCRIPTION OF DRAWINGS

[0031] The accompanying drawings, which form a part of the present application, are used to provide further understanding of the present application, and serve as an explanation of the illustrative embodiments of the present application, and do not constitute improper limitations to the present application. In the drawings:

[0032] Figure 1 is a structural schematic diagram of one specific embodiment of the device for catalytic cracking in the application;

[0033] Figure 2 is a structural schematic diagram of one specific embodiment of the inner conveying pipe and distribution inner member in the application.

[0034] Explanation of reference signs

[0035] 1-multi-stage reaction unit, 11-multi-diameter riser, 11a-first reaction area, 11b-second reaction area, 11c-third reaction area, 11d-multi-stage reaction pre-lifting section, 12-multi-stage reaction settler, 12a-multi-stage reaction stripping section, 12b-multi-stage reaction settling section, 12c-multi-stage reaction cyclone, 13-inner conveying pipe, 13a-inner conveying hole, 14-distribution inner member, 14a-distribution hole, 14b-distribution cylinder, 14c-end distribution plate, 14d-side passage, 15-multi-stage reaction catalyst outlet;

[0036] 2 - cracking reaction unit, 21 - cracking riser, 21a - cracking pre-lift section, 21b - cracking reaction section, 22 - cracking distributor, 23 - cracking settler, 23a - cracking stripping section, 23b - turbulent reaction section, 23c - cracking settling section, 23d - cracking cyclone, 24 - cracking gas phase transfer line, 25 - cracking catalyst outlet;

[0037] 3 - regeneration unit, 31 - regenerated catalyst outlet, 32 - regeneration cyclone, 33 - regeneration air inlet, 34 - regeneration flue gas outlet;

[0038] 4 - catalyst heat remover; 5 - spent catalyst line; 6 - regenerated catalyst line; 7 - multi-stage reaction feed unit; 8 - cracking feed unit; 9 - quench oil gas unit; 10 - stripping steam unit;

[0039] A - multi-stage reaction pre-lift gas; B - cracking pre-lift gas; C - regeneration air; D - regeneration flue gas; E - post-reaction oil gas; F - multi-stage reaction stripping steam; G - low-temperature water vapor; H - high-temperature water vapor. DETAILED DESCRIPTION

[0040] The specific embodiments of the present application will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are merely intended to illustrate and explain the present application, and are not intended to limit the present application.

[0041] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "connected", "connected" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrally connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be abutted, or it can be the internal communication or mutual interaction relationship of two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0042] It should be understood that the terms "upper", "lower", "front", "rear", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated, therefore, the features limited by "first", "second" can explicitly or implicitly include one or more of the features.

[0043] In one basic embodiment of the present application, see Figure 1The device for catalytic cracking comprises a multi-stage reaction unit 1 and a cracking reaction unit 2, the multi-stage reaction unit 1 comprises a multi-diameter riser 11 and a multi-stage reaction settler 12, and the cracking reaction unit 2 comprises a cracking riser 21 and a cracking settler 23; the multi-diameter riser 11 comprises a first reaction zone 11a, a second reaction zone 11b and a third reaction zone 11c which are sequentially connected in series along the length direction of the multi-diameter riser 11, the outlet of the third reaction zone 11c is communicated with the multi-stage reaction settler 12, the inner diameter of the second reaction zone 11b is larger than the inner diameters of the first reaction zone 11a and the third reaction zone 11c, and an inner conveying pipe 13 extending to the inside of the second reaction zone 11b is arranged at the connection position of the third reaction zone 11c and the second reaction zone 11b; the cracking settler 23 comprises a cracking stripping section 23a, a turbulent reaction section 23b and a cracking settling section 23c which are sequentially arranged along the length direction of the cracking settler 23, and the outlet of the cracking riser 21 is located in the turbulent reaction section 23b, and the cracking stripping section 23a is provided with a cracking catalyst outlet 25 communicated with the second reaction zone 11b.

[0044] The device for catalytic cracking can be applied to catalytic cracking or catalytic cracking process in various chemical production fields, and is especially suitable for catalytic cracking / catalytic cracking of heavy oil and light hydrocarbon, for example, production of ultra-low olefin gasoline and high-yield cracking gas; the reaction unit 1 is used for catalytic cracking / catalytic cracking of heavy raw materials (heavy oil), and the cracking reaction unit 2 is used for catalytic cracking / catalytic cracking of light raw materials (light hydrocarbon). It should be emphasized that the device for catalytic cracking in the present application is based on the parallel arrangement of the multi-stage reaction unit 1 and the cracking reaction unit 2, and the switching between the two operation modes of ultra-low olefin gasoline and high-yield cracking gas can be realized by replacing the catalyst and adjusting the operation conditions, and the adjustment depth and change range of the two modes can be increased, and the processing amount of light hydrocarbon with a large proportion relative to heavy oil can be realized; wherein the light hydrocarbon can come from outside the multi-stage reaction unit 1 in the device or even outside the workshop or factory. In addition, while the multi-stage reaction unit 1 and the cracking reaction unit 2 are connected in parallel, the catalyst after cracking of the light hydrocarbon is reused to the second reaction zone 11b from the cracking catalyst outlet 25, so that the high-temperature spent catalyst after reaction of the light hydrocarbon has high cracking activity, and is supplemented to the second reaction zone 11b of the multi-stage reaction unit 1, so as to effectively improve the catalyst concentration and catalyst activity in the multi-stage reaction unit 1, and realize the close coupling of the multi-stage reaction unit 1 and the cracking reaction unit 2.

[0045] The inventor found in the research process that the superficial gas velocity in the diameter expansion section of the conventional MIP-CGP reactor is too low, which is not enough to take the catalyst to the third reaction zone 11c, and is prone to choking and even accumulation of catalyst in the diameter expansion section, causing device accidents; if the superficial gas velocity is too high, the catalyst dense phase section cannot be formed in the diameter expansion section, which cannot meet the process requirements. By arranging the inner conveying pipe 13 in the second reaction zone 11b (i.e. the diameter expansion section) with a larger inner diameter in the multi-diameter riser 11, the above-mentioned defects can be effectively overcome, and the following effects can be achieved: first, when the superficial gas velocity in the second reaction zone 11b is reduced to form a turbulent bed, when the upper interface of the turbulent bed submerges the bottom port of the inner conveying pipe 13, the catalyst at the top of the turbulent bed can be sucked away, that is, the height of the turbulent bed in the second reaction zone 11b can be controlled. Second, the upper part of the diameter expansion section coaxial with the inner conveying pipe 13 at the upper part of the second reaction zone 11b can be used as the dilute phase section of the turbulent bed, and a large amount of particles carried by the gas are thrown to the dilute phase section above the turbulent bed. Due to the decrease of gas flow velocity, a free space for solid particle sedimentation is formed, and the catalyst particles carried by the turbulent bed will fall into the lower part of the second reaction zone 11b again, thereby strengthening the backmixing of the catalyst. Since a considerable amount of gas is stored in the free space, it can provide a buffer space for the gas pulsation in the multi-diameter riser 11. The above two effects can to some extent avoid the large and rapid accumulation of catalyst in the multi-diameter riser 11 and the rapid and sharp fluctuation of gas pressure, thereby widening the range of the best operating gas linear velocity in the second reaction zone 11b. Third, the gas-solid fluidization in the second reaction zone 11b is in a turbulent bed, and at the bottom of the turbulent bed, the solid phase is turbulent and continuous, the solid-gas ratio in the unit space is large, the bubble diameter of the solid particles in the turbulent bed is small, and the gas-solid contact efficiency is enhanced. Generally, the gas-solid contact efficiency is higher than that of various forms of conveying bed, which is suitable for some fields that require further enhancement of gas-solid contact efficiency. Fourth, if a gas velocity greater than 2 m / s is used, the gas velocity in the diameter expansion section which is the same height as the inner conveying pipe 13 can be small, so that the catalyst thrown up by the high-speed gas below can fall into the second reaction zone 11b at the bottom, thereby increasing the catalyst density at the bottom of the second reaction zone 11b and strengthening the gas-solid mixing and contact.

[0046] Compared with the conventional MIP-CGP reactor, the inner conveying pipe 13 provided by the application changes the flow state of the gas and the catalyst in the second reaction zone 11b to some extent. The gas superficial velocity range in the second reaction zone 11b is wider, the conventional MIP-CGP reactor has a diameter expansion section, the superficial gas velocity is 1.4-2.8 m / s, and the industrial operation device is generally preferred to be 1.5-2.0 m / s; in the multi-stage reaction unit 1 provided by the application, the superficial gas velocity in the second reaction zone 11b is 0.7-3.5 m / s, which can form a dense phase section at the bottom of the second reaction zone 11b, and the preferred operating range of the superficial gas velocity is 0.9-2.5 m / s; correspondingly, the ratio of the inner diameter of the second reaction zone 11b to the inner diameter of the first reaction zone 11a is larger in the application, and in the preferred case, the ratio of the inner diameter of the second reaction zone 11b to the inner diameter of the first reaction zone 11a is 2-5:1, and more preferably 1.7-3.5:1.

[0047] In the application, the device for catalytic cracking is generally vertically arranged when in use, the length direction of the multi-diameter riser 11 is vertical, the first reaction zone 11a, the second reaction zone 11b and the third reaction zone 11c are sequentially connected from bottom to top, the length direction of the cracking settler 23 is also vertical, and the cracking stripping section 23a, the turbulent reaction section 23b and the cracking settling section 23c are sequentially connected from bottom to top; the multi-stage reaction settler 12 and the multi-diameter riser 11 can be coaxially arranged or arranged side by side.

[0048] In the application, the multi-stage reaction settler 12 generally includes a multi-stage reaction stripping section 12a and a multi-stage reaction settling section 12b arranged from bottom to top, and one or more multi-stage reaction cyclone separators 12c are arranged in the multi-stage reaction settling section 12b, so that the material of the multi-diameter riser 11 can enter the multi-stage reaction settling section 12b and be separated by the multi-stage reaction cyclone separator 12c, so that the separated spent catalyst can enter the multi-stage reaction stripping section 12a, be stripped by the multi-stage reaction stripping steam F, and then be discharged, and can be returned to the multi-stage reaction unit 1 after being treated by air coking regeneration in the catalyst regenerator for recycling.

[0049] The basic embodiment of the device for catalytic cracking provided above is applied to catalytic cracking, and includes the following steps:

[0050] The heavy feedstock is mixed with the multi-stage reaction catalyst at the bottom of the first reaction zone 11a after being atomized by steam to form a multi-stage reaction mixture, which is input from the inlet of the first reaction zone 11a and sequentially enters the first reaction zone 11a and the second reaction zone 11b in an upward direction. The diameter of the second reaction zone 11b is expanded to increase the residence time of the multi-stage reaction mixture and allow sufficient mixing and contact, so that the secondary reactions of the heavy oil and the intermediate fraction are fully completed. The multi-stage reaction mixture then enters the third reaction zone 11c from the inner conveying pipe 13 to perform multi-stage catalytic reactions and obtain a multi-stage reaction product. The diameter of the inner conveying pipe 13 and the riser of the third reaction zone 11c are reduced to increase the flow rate of the mixture, so that the mixture quickly enters the multi-stage reaction settler 12 for multi-stage reaction separation to obtain a multi-stage reaction oil and gas product and a multi-stage reaction spent catalyst. The spent multi-stage reaction catalyst with carbon after the reaction is discharged after being subjected to or not subjected to steam stripping;

[0051] The cracking mixture formed by mixing the light feedstock with the cracking catalyst is input from the inlet of the cracking riser 21, performs cracking catalytic reactions in the cracking riser 21 to obtain a cracking reaction product, and then enters the turbulent reaction section 23b to perform turbulent reactions. After that, the cracking reaction product is separated in the cracking settling section 23c and subjected to cracking stripping in the cracking stripping section 23a to obtain a cracking oil and gas product and a cracking spent catalyst.

[0052] The cracking spent catalyst is input from the cracking catalyst outlet 25 into the second reaction zone 11b, and is mixed with the multi-stage reaction mixture to increase the activity and density of the multi-stage reaction catalyst in the second reaction zone 11b.

[0053] In the present application, the heavy feedstock is petroleum hydrocarbon and / or other mineral oil. The petroleum hydrocarbon is selected from at least one of vacuum gas oil (VGO), atmospheric gas oil (AGO), coking gas oil (CGO), deasphalted oil (DAO), vacuum residue (VR), atmospheric residue (AR), and hydrocracking heavy oil. The other mineral oil is selected from at least one of coal liquefaction oil, oil sand oil, and shale oil. Preferably, the heavy feedstock is selected from at least one of vacuum gas oil, atmospheric gas oil, coking gas oil, deasphalted oil, vacuum residue, atmospheric residue, and hydrocracking heavy oil. The VGO, AGO, CGO, DAO, VR, and AR are full or partial fractions before hydrogenation, or full or partial fractions after hydrogenation.

[0054] In the present invention, the light feedstock is selected from at least one of olefin-rich gasoline, diesel, and light hydrocarbon not rich in olefin or rich in olefin having 4-8 carbon atoms, wherein the olefin-rich gasoline can be one or more than one of gasoline obtained by catalytic cracking using the apparatus provided in the present invention, conventional catalytic cracking gasoline, other catalytic cracking gasoline, coking gasoline, thermal cracking gasoline, thermal cracking gasoline, or a mixture of one or more than one thereof; and the light hydrocarbon not rich in olefin can be selected from one or more than one of straight-run naphtha, straight-run gasoline, hydrogenated naphtha, alkane having 4-8 carbon atoms, and raffinate.

[0055] In the present invention, the multi-stage reaction catalyst and the cracking catalyst in the method can use all types of catalytic cracking or catalytic cracking catalysts, and the active component thereof is selected from one or more of catalysts containing or not containing rare earth Y or HY type zeolite, containing or not containing rare earth Y type zeolite, ZSM-5 series zeolite, or high-silicon zeolite with a five-membered ring structure prepared by other methods, and amorphous silicon aluminum catalyst. Among them, the multi-stage reaction catalyst and the cracking catalyst can use the same catalyst, or different catalysts.

[0056] In the use of the above apparatus, in order to control the reaction temperature of the multi-stage reaction unit 1, a quenching agent can be injected at any position of the upper part of the first reaction zone 11a and the middle part of the second reaction zone 11b of the multi-stage reaction unit 1, and preferably, a quenching oil gas unit 9 is provided at the top of the first reaction zone 11a to the bottom of the second reaction zone 11b. The quenching agent can be selected from at least one of water, raffinate oil, gasoline, diesel, and waste oil, and the injection amount is 1-10 wt% of the amount of the catalytic feedstock (heavy feedstock), and the temperature of the quenching agent is 10-200℃, preferably 10-30℃.

[0057] In the present application, most of the catalysts in the cracking reaction unit 2 fall into the turbulent reaction section 23b, so that the catalyst density of the turbulent reaction section 23b and the cracking stripping section 23a is large. By controlling the catalyst output at the bottom of the cracking settler 23, the catalyst in the middle and top of the cracking settler 23 gradually falls into the bottom cracking stripping section 23a, and the catalyst falling into the cracking stripping section 23a can be output from the cracking catalyst outlet 25 after being stripped by steam or not. The cracking catalyst outlet 25 is connected to any position from the end of the first reaction zone 11a to the middle of the second reaction zone 11b through a pipeline, so as to input the cracking spent catalyst into the second reaction zone 11b of the multi-diameter riser 11. In addition, a pipeline can be additionally provided to connect the cracking catalyst outlet 25 with the catalyst regenerator for recycling. Preferably, the cracking catalyst outlet 25 is located at the bottom of the cracking stripping section 23a and is connected to the bottom of the second reaction zone 11b (close to one end of the first reaction zone 11a) through a pipeline. A slide valve can be provided on the pipeline to adjust the amount of cracking spent catalyst input into the second reaction zone 11b by controlling the opening degree of the slide valve, and the catalyst inventory in the cracking settler 23 can also be adjusted.

[0058] Since the cracking catalyst has low coke content and high temperature after reacting with light hydrocarbons, it still has high catalytic activity. When input into the second reaction zone 11b, the flow rate of the catalyst in the second reaction zone 11b and the catalytic activity of the catalyst are improved, which is beneficial to strengthening the catalytic reaction in the multi-diameter riser 11. The light hydrocarbon reaction oil gas separated by the cracking settler 23 does not enter the multi-diameter riser 11 for heavy oil reaction, which does not affect the flow rate and flow velocity of the oil gas in the second reaction zone 11b, and further does not affect the gas-solid fluidization in the second reaction zone 11b. At the same time, the residence time of the light hydrocarbons in the high-temperature reaction zone in the cracking reaction unit 2 is shortened, and the degree of thermal cracking reaction is reduced.

[0059] In the present application, the inner diameter of the inner conveying pipe 13 is smaller than that of the second reaction zone 11b. Preferably, the ratio of the inner diameter of the inner conveying pipe 13 to that of the third reaction zone 11c is 0.9-1.2:1, more preferably, the ratio of the inner diameter of the inner conveying pipe 13 to that of the third reaction zone 11c is 0.95-1.05:1, so that the inner diameters of the two are equivalent, so as to further widen the adjustment range of the gas superficial linear velocity in the second reaction zone 11b, and make the reaction oil gas flow rate (representing the processing capacity of the device) that the multi-stage reaction unit 1 can withstand be adjusted or fluctuate in a larger range.

[0060] In the present application, the length of the inner conveying pipe 13 is less than the length of the second reaction zone 11b, preferably, the ratio of the length of the inner conveying pipe 13 to the length of the second reaction zone 11b is 0.15-0.8:1, more preferably 0.2-0.6:1, which can better make the gas-solid fluidization state in the second reaction zone 11b and the turbulent flow effect better. It should be noted that the second reaction zone 11b can be cylindrical, or can be a circular truncated cone shape gradually expanding from bottom to top, or can be a two-stage or three-stage expanding cylindrical shape; the height of the second reaction zone 11b refers to the height sum of the region segment itself, the transition segment between the first reaction zone 11a and the second reaction zone 11b, and the transition segment between the second reaction zone 11b and the third reaction zone 11c.

[0061] In the present application, as a preferred embodiment of the inner conveying pipe 13, the distance between the bottom port of the inner conveying pipe 13 and the bottom of the second reaction zone 11b (i.e. the outlet of the first reaction zone 11a) is 2-8m, preferably 3-6m; the length of the inner conveying pipe 13 is 2-7m, preferably 3-5m; at this time, the height of the turbulent bed in the second reaction zone 11b can be better controlled.

[0062] The inventor of the present application found that, from the axial distribution, the axial density of the catalyst particles in the expansion section is in an "S-shaped" distribution with a high concentration in the lower part. The height of the dense phase section is affected by the gas velocity and the particle conveying capacity, but is concentrated in the lower part of the expansion section below 60% of the height. From the radial distribution of the catalyst particles, the maximum particle velocity is in the center of the riser, the particle velocity in the central region maintains a relatively constant value, and the particle velocity decreases slowly from the center to the wall. When r / R (r represents the distance from the central axis, and R is the pipe radius) reaches a certain value, the particle velocity suddenly decreases and is almost zero near the edge wall. The edge wall effect exists in the entire variable-diameter riser. In the lower part of the pneumatic conveying riser, the gas velocity is above 10 m / s, and the axial velocity of the catalyst particles is high in the region where r / R<0.8. However, in the expansion section, the gas superficial velocity is 1.5-3 m / s, and the edge wall effect is more obvious. In the lower part of the expansion section, the axial velocity of the catalyst particles is high in the region where r / R<0.7, but the axial velocity of the catalyst particles near the edge wall is zero or even negative. In the upper part of the expansion section, the axial velocity of the catalyst particles is high in the region where r / R<0.6, but the axial velocity of the catalyst particles near the edge wall is maintained at about 0, that is, a large part of the catalyst is in suspension in this section, which may stay in the expansion section for too long, affecting the optimal process effect. Based on this, at least one inner conveying hole 13a is preferably arranged on the side wall of the inner conveying pipe 13, and the distance between the inner conveying hole 13a and the inlet of the third reaction zone 11c is 0.5-2 m. The arrangement of the inner conveying hole 13a can make the gas in the upper part of the second reaction zone 11b in the expansion section and the coaxial part of the inner conveying pipe 13 in a flowing state, so as to prevent the occurrence of a dead zone without gas flow in the upper part of the second reaction zone 11b, and further improve the turbulent flow effect and catalytic reaction efficiency in the second reaction zone 11b.

[0063] In the present application, the inner conveying hole 13a is preferably arranged in multiple numbers and can be uniformly distributed in the circumferential direction on the inner conveying pipe 13. Further preferably, the ratio of the total area of the at least one inner conveying hole 13a to the cross-sectional area of the inner conveying pipe 13 is 0.05-0.3:1. The cross-sectional area of the inner conveying pipe 13 refers to the area of the cross section perpendicular to the length direction of the inner conveying pipe 13.

[0064] In the present application, the transition section between the first reaction zone 11a and the second reaction zone 11b and the transition section between the second reaction zone 11b and the third reaction zone 11c are in a dome or circular truncated cone shape and are coaxially arranged with the entire multi-stage reaction unit 1. Preferably, the first reaction zone 11a, the second reaction zone 11b, the third reaction zone 11c and the inner conveying pipe 13 are coaxially arranged.

[0065] As a preferred embodiment, the ratio of the inner diameters of the first reaction zone 11a, the second reaction zone 11b and the third reaction zone 11c is 1:2-5:0.7-1.5, and the ratio of the lengths is 1:0.3-2:0.5-2. At this time, it is more advantageous to prolong the residence time of the oil agent in the second reaction zone 11b and can fully mix the contact, and fully complete the secondary reaction of the heavy oil and the intermediate fraction thereof.

[0066] In the present application, the cracking settler 23 is in a two-stage expanding diameter structure, the outer diameters of the cracking stripping section 23a, the turbulent reaction section 23b and the cracking settling section 23c are sequentially increased, and the cracking riser 21 is located in the turbulent reaction section 23b or the transition section between the turbulent reaction section 23b and the cracking settling section 23c. As a preferred embodiment of the cracking settler 23, the ratio of the inner diameters of the turbulent reaction section 23b, the cracking stripping section 23a and the cracking settling section 23c is 1:0.4-0.8:2.5-5, and the ratio of the lengths is 1:1.5-3:1.5-4. At this time, it is more advantageous to efficiently and fully react the light hydrocarbon with the catalyst in the turbulent reaction section 23b, and to realize the efficient contact reaction of the light hydrocarbon with the catalyst at a lower temperature and a low space velocity.

[0067] In the present application, the cracking riser 21 and the cracking settler 23 of the cracking reaction unit 2 are preferably coaxially arranged.

[0068] As a preferred embodiment of the present application, the ratio of the lengths of the multi-diameter riser 11 and the cracking riser 21 is 1:0.5-1.2, and more preferably 1:0.6-1. The ratio of the inner diameter of the first reaction zone 11a in the multi-diameter riser 11 to the inner diameter of the cracking riser 21 is 1:0.2-1. At this time, the coupling effect between the multi-stage reaction unit 1 and the cracking reaction unit 2 can be better realized. Generally, the height of the multi-diameter riser 11 in a laboratory medium-sized device is about 20 meters, and the height of the multi-diameter riser 11 in industrial production is about 40 meters.

[0069] As another preferred embodiment of the present application, referring to Figure 2 , a distribution inner member 14 connected with the first reaction zone 11a is arranged in the second reaction zone 11b, and a plurality of distribution holes 14a are arranged on the distribution inner member 14, that is, the distribution inner member 14 is an open distribution member. The main body of the distribution inner member 14 is located in the transition section between the first reaction zone 11a and the second reaction zone 11b, and its function is to rapidly reduce the high-speed gas-solid particles in the first reaction zone 11a to the gas-solid fluidization state required by the second reaction zone 11b.

[0070] In this invention, the distribution internal component 14 can be an open distribution plate with an opening ratio of 8-35%; it can also be a cap-type distributor with a mushroom-shaped, conical, or umbrella-shaped top that outputs oil and gas from a side channel. The cap-type distributor can be a conventional umbrella-type distributor, mushroom-shaped distributor, or conical cap-type distributor. Specifically, the distribution internal component 14 includes a distribution cylinder 14b connected to the first reaction zone 11a and an end distribution plate 14c connected to the distribution cylinder 14b. Both the distribution cylinder 14b and the end distribution plate 14c are provided with distribution holes 14a. The end distribution plate 14c is located at the end of the distribution cylinder 14b away from the first reaction zone 11a. The end distribution plate 14c can be umbrella-shaped or dome-shaped, for example, an arched (convex) distribution plate, an irregular (basin) distribution plate, or a concave distribution plate.

[0071] In a preferred embodiment of the end distribution plate 14c, the ratio of the sum of the areas of the plurality of distribution holes 14a on the end distribution plate 14c (i.e., the total hole area) to the vertical projected area of ​​the end distribution plate 14c is 0.1-0.3:1. This allows the gas above the end distribution plate 14c to flow smoothly and prevents catalyst from accumulating on the end distribution plate 14c. The vertical projected area of ​​the end distribution plate 14c refers to the area occupied by the shadow of the outer contour of the end distribution plate 14c on the vertical plane after horizontal parallel light rays illuminate the end distribution plate 14c.

[0072] In this invention, the distribution holes 14a on the distribution cylinder 14b can be rectangular or elliptical. Preferably, the ratio of the sum of the areas of the distribution holes 14a on the distribution cylinder 14b to the cross-sectional area of ​​the first reaction zone 11a is 0.6-4:1; this can better improve the deceleration and distribution effect on high-speed gas-solid particles in the first reaction zone 11a. The cross-sectional area of ​​the first reaction zone 11a refers to the area of ​​the cross-section perpendicular to the length direction of the first reaction zone 11a.

[0073] In a preferred embodiment of the distribution cylinder 14b, a side channel 14d extending outward from the distribution hole 14a on the distribution cylinder 14b is provided. The opening section of the side channel 14d away from the distribution cylinder 14b is an inclined surface facing the first reaction zone 11a. The cross-sectional shape of the side channel 14d (the section perpendicular to the length direction of the side channel 14d) corresponds to the distribution hole 14a on the distribution cylinder 14b and can be rectangular or elliptical. The opening section of the side channel 14d away from the distribution cylinder 14b is generally not perpendicular to the axis of the side channel 14d. This opening section is an inclined surface facing the first reaction zone 11a, that is, its extended section forms a certain upward angle with the axis of the multi-stage reaction unit 1. The upper part of this opening section is part of the side channel 14d to avoid the outlet of the side channel 14d being blocked by the catalyst as much as possible, ensuring the unobstructed flow of the outlet of the side channel 14d.

[0074] As another preferred embodiment of the distribution cylinder 14b, the ratio of the area of the end distribution plate 14c to the cross-sectional area of the second reaction zone 11b is 0.7-0.85:1, so that the gas velocity at the edge of the end distribution plate 14c is above 2.5 m / s, preferably above 3.5 m / s, to ensure that no catalyst accumulation occurs at the bottom of the second reaction zone 11b or even in the transition section, causing an operating accident of the device. Here, the area of the end distribution plate 14c is the projected area of the outer contour of the end distribution plate 14c, and the cross-sectional area of the second reaction zone 11b is the area of the cross section perpendicular to the length direction of the second reaction zone 11b.

[0075] In the present application, a wear-resistant lining, such as a ceramic wear-resistant lining, is installed or applied in the inner conveying hole 13a and / or the distribution hole 14a.

[0076] In the present application, in order to fully mix the raw materials and the catalyst, preferably, the multi-diameter riser 11 further comprises a multi-stage reaction pre-lifting section 11d connected to the inlet of the first reaction zone 11a, the cracking riser 21 comprises a cracking pre-lifting section 21b and a cracking reaction section 21a connected in series along the length direction thereof, the outlet of the cracking reaction section 21a is located at one end of the turbulent reaction section 23b close to the cracking stripping section 23a, the transition section between the multi-stage reaction pre-lifting section 11d and the first reaction zone 11a is in communication with the multi-stage reaction feeding unit 7, and the transition section between the cracking pre-lifting section 21b and the cracking reaction section 21a is in communication with the cracking feeding unit 8. The multi-stage reaction pre-lifting gas A is injected through the multi-stage reaction pre-lifting section 11d, mixed with the multi-stage reaction catalyst, and then goes up, the heavy raw materials atomized by steam enter the multi-diameter riser 11 from the multi-stage reaction feeding unit 7, so that the heavy raw materials contact and react with the multi-stage reaction catalyst in the first reaction zone 11a; the cracking pre-lifting gas B is injected through the cracking pre-lifting section 21b, mixed with the cracking catalyst, and then goes up, the light raw materials atomized by steam enter the cracking riser 21 from the cracking feeding unit 8, so that the light raw materials contact and react with the cracking catalyst in the cracking reaction section 21a.

[0077] In the present application, in order to improve the contact effect of the light hydrocarbon reaction mixture entering the turbulent reaction section 23b with the catalyst and improve the catalytic reaction efficiency, preferably, a cracking distributor 22 is arranged at the outlet of the cracking reaction section 21a.

[0078] In the present application, the gas phase outlet of the cracking settling section 23c can be merged into the main oil and gas pipeline, or can be communicated with the multi-stage reaction settler 12, for example, the multi-stage reaction settler 12 is provided with a gas collecting chamber at the top, and the gas phase outlet of the cracking settling section 23c is communicated with the gas collecting chamber through the cracking gas phase conveying pipe 24, so that the oil and gas E (including the heavy feedstock oil and gas after reaction and the light feedstock oil and gas after reaction) after reaction is discharged from the gas collecting chamber. The bottom of the cracking stripping section 23a can be provided with a stripping steam unit 10 to introduce steam to strip the catalyst in the cracking stripping section 23a.

[0079] The device for catalytic cracking provided by the present application can be used in combination with a corresponding catalyst regenerator for the multi-stage reaction unit 1 and the cracking reaction unit, and when the multi-stage reaction catalyst and the cracking catalyst are the same, they can share one catalyst regenerator. As a preferred embodiment of the present application, the device further comprises a regeneration unit 3, the multi-stage reaction settler 12 is provided with a multi-stage reaction catalyst outlet 15 communicated with the inlet of the regeneration unit 3, and the regenerated catalyst outlet 31 of the regeneration unit 3 is communicated with the multi-diameter riser 11 and / or the cracking riser 21. The cracking catalyst outlet 25 is not only communicated with the second reaction zone 11b, but also communicated with the inlet of the regeneration unit 3, so as to directly input part of the spent catalyst of the cracking reaction unit 2 into the regeneration unit 3.

[0080] In the present application, the regeneration unit 3 is provided with a regeneration cyclone 32, and the bottom is provided with a regeneration air inlet 33 and the top is provided with a regeneration flue gas outlet 34. The spent catalyst enters the regeneration unit 3 through the spent catalyst pipeline 5, and is in contact with the regeneration air C entering the regeneration air inlet 33 to generate an oxidation reaction, and the regeneration flue gas D is output from the regeneration flue gas outlet 34 to enter the flue gas turbine and the like for further energy recovery and treatment; the high-temperature regenerated catalyst generated by burning the coke enters the catalyst heat extractor 4 through the regeneration pipeline 6, and the low-temperature water vapor G enters the catalyst heat extractor 4 from the heat extraction steam inlet, and becomes high-temperature water vapor H after heat extraction from the regenerated catalyst, and is output from the heat extraction steam outlet. The cooled regenerated catalyst is circulated to the bottom of the first reaction zone 11a and the bottom of the cracking riser 21 through the regeneration pipeline 6 for recycling.

[0081] In the present application, part or all of the multi-stage reaction catalyst and part or all of the cracking catalyst use the regenerated catalyst output from the regenerated catalyst outlet 31.

[0082] Based on the device for catalytic cracking provided above, the second aspect of the present application provides a method for applying the device to catalytic cracking, which comprises the following steps:

[0083] The multi-stage reaction mixture formed by mixing the heavy feedstock and the multi-stage reaction catalyst is input from the inlet of the first reaction zone 11a, sequentially enters the first reaction zone 11a, the second reaction zone 11b, and then enters the third reaction zone 11c from the inner conveying pipe 13 to perform multi-stage catalytic reaction to obtain a multi-stage reaction product, and the multi-stage reaction product is separated by the multi-stage reaction settler 12 to obtain a multi-stage reaction oil gas product and a multi-stage reaction spent catalyst;

[0084] The cracking mixture formed by mixing the light feedstock and the cracking catalyst is input from the inlet of the cracking riser 21, and the cracking catalytic reaction is performed in the cracking riser 21 to obtain a cracking reaction product, and after the cracking reaction product enters the turbulent reaction section 23b to perform turbulent reaction, the cracking separation is performed in the cracking settling section 23c and the cracking stripping is performed in the cracking stripping section 23a to obtain a cracking oil gas product and a cracking spent catalyst;

[0085] The cracking spent catalyst is input from the cracking catalyst outlet 25 into the second reaction zone 11b and mixed with the multi-stage reaction mixture.

[0086] The device and method provided by the application have multiple operation modes. For example, in the ultra-low olefin gasoline operation mode, the multi-stage reaction unit 1 adopts a catalyst for producing more gasoline and having the function of reducing olefins, the amount of catalyst circulating, the amount of quenching agent injected into the quenching oil gas unit 9, and the amount of regenerated catalyst or cooled regenerated catalyst (generally at a temperature of 560-660 DEG C) or carbon-containing spent catalyst with a carbon content of less than 0.5% are not supplemented or supplemented at the bottom or middle part of the second reaction zone 11b, the temperature in the second reaction zone 11b is controlled at 510-540 DEG C, the optimization range is 515-530 DEG C, the inlet temperature of the inner conveying pipe 13 is controlled at 510-540 DEG C, and the optimization range is 515-530 DEG C, and the ultra-low olefin gasoline production mode can be realized.

[0087] At the same time, the cracking reaction unit 2 cracks various catalytic light gasoline rich in olefins, coking gasoline, etc., which can further reduce the amount of high-olefin gasoline in the whole plant and reduce the olefin content in the whole plant gasoline pool, and the outlet temperature of the cracking riser 21 is controlled at 540-620 DEG C, and preferably at 560-600 DEG C.

[0088] For another example, in the multi-cracking gas production mode, the multi-stage reaction unit 1 adopts a catalytic cracking catalyst for producing more cracking gas, and the regenerated catalyst or the cooled regenerated catalyst (generally at a temperature of 580-680 DEG C) or the carbon-containing spent catalyst with a carbon content of less than 0.5% (generally at a temperature of 580-680 DEG C) is not supplemented or supplemented at the bottom or middle part of the second reaction zone 11b, the temperature in the second reaction zone 11b is controlled at 560-660 DEG C, the optimization range is 560-600 DEG C, the inlet temperature of the inner conveying pipe 13 is controlled at 550-640 DEG C, and the optimization range is 560-600 DEG C, and the multi-cracking gas production operation mode can be realized.

[0089] Meanwhile, the cracking reaction unit 2 recycles light hydrocarbon, such as gasoline or diesel, rich in C4-C8 olefins, and the outlet temperature of the cracking riser 21 is controlled at 560-660 ℃, preferably 580-640 ℃; in this way, the yield of cracking gas in the whole plant can be further increased, i.e. the yield of raw materials required by light hydrocarbon processing devices such as MTBE, light gasoline etherification, and polypropylene can be increased, and the structure of refining products in the whole plant can be regulated and controlled.

[0090] In the present application, the temperature of the regenerated catalyst before the heavy feedstock or the light feedstock is contacted with the catalyst (i.e. oil agent) is 660-760 ℃.

[0091] Based on the device and method provided by the present application, the apparent residence time of the multi-stage reaction mixture in the first reaction zone 11a is 0.8-2 s, the apparent residence time of the oil gas in the second reaction zone 11b is 5-15 s, and the apparent residence time of the oil gas in the third reaction zone 11c is 0.5-1.5 s; the residence time of the cracking mixture in the cracking riser 21 is 0.8-3.5 s, more preferably 1-2.5 s; and the residence time in the turbulent flow reaction section 23b is 3-13 s.

[0092] As a relatively preferred embodiment of the catalytic cracking device in the application, the catalytic cracking device comprises a multi-stage reaction unit 1, a cracking reaction unit 2 and a regeneration unit 3, the multi-stage reaction unit 1 comprises a multi-diameter riser 11 and a multi-stage reaction settler 12; the multi-diameter riser 11 comprises a multi-stage reaction pre-lifting section 11d, a first reaction zone 11a, a second reaction zone 11b and a third reaction zone 11c which are sequentially and coaxially connected along the length direction of the multi-diameter riser 11, the outlet of the third reaction zone 11c is communicated with the multi-stage reaction settler 12, a quenching oil gas unit 9 is arranged at the top of the first reaction zone 11a to the bottom of the second reaction zone 11b, the ratio of the inner diameters of the first reaction zone 11a, the second reaction zone 11b and the third reaction zone 11c is 1:2-5:0.7-1.5, the ratio of the lengths of the first reaction zone 11a, the second reaction zone 11b and the third reaction zone 11c is 1:0.3-2:0.5-2, an inner conveying pipe 13 extending to the inside of the second reaction zone 11b is arranged at the connection position of the third reaction zone 11c and the second reaction zone 11b, the ratio of the inner diameter of the inner conveying pipe 13 to the third reaction zone 11c is 0.9-1.2:1, the ratio of the length of the inner conveying pipe 13 to the second reaction zone 11b is 0.15-0.8:1, a plurality of inner conveying holes 13a are arranged on the side wall of the inner conveying pipe 13, the distance between the inner conveying holes 13a and the inlet of the third reaction zone 11c is 0.5-2 m, the ratio of the total area of the plurality of inner conveying holes 13a to the cross-sectional area of the inner conveying pipe 13 is 0.05-0.3:1, a distribution inner member 14 connected with the first reaction zone 11a is arranged in the second reaction zone 11b, the distribution inner member 14 comprises a distribution cylinder 14b connected with the first reaction zone 11a and an end distribution plate 14c connected with the distribution cylinder 14b, a plurality of distribution holes 14a are arranged on the distribution cylinder 14b and the end distribution plate 14c, the end distribution plate 14c is located at the end of the distribution cylinder 14b away from the first reaction zone 11a, the ratio of the area of the end distribution plate 14c to the cross-sectional area of the second reaction zone 11b is 0.7-0.85:1, the ratio of the sum of the areas of the plurality of distribution holes 14a arranged on the end distribution plate 14c to the vertical projection area of the end distribution plate 14c is 0.1-0.3:1, the ratio of the sum of the areas of the distribution holes 14a on the distribution cylinder 14b to the cross-sectional area of the first reaction zone 11a is 0.6-4:1, a side passage 14d extending to the outside of the distribution cylinder 14b is arranged at the distribution hole 14a on the distribution cylinder 14b, the opening cross section of the side passage 14d away from the distribution cylinder 14b is a slope surface facing the first reaction zone 11a, a transition section between the multi-stage reaction pre-lifting section 11d and the first reaction zone 11a is communicated with the multi-stage reaction feeding unit 7, the multi-stage reaction settler 12 comprises a multi-stage reaction stripping section 12a and a multi-stage reaction settling section 12b arranged from bottom to top, one or more multi-stage reaction cyclone separators 12c are arranged in the multi-stage reaction settling section 12b, a multi-stage reaction catalyst outlet 15 is arranged at the bottom of the multi-stage reaction stripping section 12a;

[0093] The cracking reaction unit 2 comprises a coaxially arranged cracking riser 21 and a cracking settler 23, the cracking riser 21 comprises a cracking pre-lifting section 21b and a cracking reaction section 21a connected in series along the length direction of the cracking riser 21, the transition section between the cracking pre-lifting section 21b and the cracking reaction section 21a is communicated with the cracking feed unit 8, the cracking settler 23 comprises a cracking stripping section 23a, a turbulent reaction section 23b and a cracking settling section 23c arranged in series along the length direction of the cracking settler 23, the outlet of the cracking reaction section 21a is located at one end of the turbulent reaction section 23b close to the cracking stripping section 23a, a cracking distributor 22 is arranged at the outlet of the cracking reaction section 21a, the bottom of the cracking stripping section 23a is provided with a cracking catalyst outlet 25 communicated with the bottom of the second reaction zone 11b, the ratio of the inner diameters of the turbulent reaction section 23b, the cracking stripping section 23a and the cracking settling section 23c is 1:0.4-0.8:2.5-5, the ratio of the lengths of the turbulent reaction section 23b, the cracking stripping section 23a and the cracking settling section 23c is 1:1.5-3:1.5-4, one or two stages of cracking cyclone separators 23d are arranged in the cracking settling section 23c, the gas phase outlet of the cracking settling section 23c is communicated with the gas collecting chamber at the top of the multi-stage reaction settler 12 through a cracking gas phase conveying pipe 24, and the bottom of the cracking stripping section 23a is provided with a stripping steam unit 10.

[0094] The regeneration unit 3 is provided with a regeneration cyclone separator 32, and the regeneration catalyst outlet 31 is arranged on the side wall, the regeneration air inlet 33 is arranged at the bottom, and the regeneration flue gas outlet 34 is arranged at the top, the multi-stage reaction catalyst outlet 15 and the cracking catalyst outlet 25 are both communicated with the feeding inlet of the regeneration unit 3 through the spent pipe 5, the regeneration catalyst outlet 31 is communicated with the multi-stage reaction pre-lifting section 11d and the cracking pre-lifting section 21b through the regeneration pipe 6, and the catalyst heat extractor 4 is arranged on the regeneration pipe 6.

[0095] The length ratio of the multi-diameter riser 11 to the cracking riser 21 is 1:0.5-1.2, and wear-resistant liners are installed or smeared in the inner conveying holes 13a and the distribution holes 14a.

[0096] The application will be described in detail through the following examples.

[0097] In the following examples, the heavy feedstock (heavy oil), light hydrocarbon I and light hydrocarbon II are provided by a refinery of China Petroleum Chemical Group Co., Ltd., the catalyst I and the catalyst II are provided by Sinopec Catalyst Co., Ltd., the product distribution and the gasoline composition are detected by chromatography, and the remaining raw materials are all conventional commercial products under the condition of no special instructions, and the parameters involved are all obtained by using the corresponding existing methods.

[0098] Example 1

[0099] The process conditions for producing ultra-low olefin gasoline using the above-described catalytic cracking device according to the relatively preferred embodiment, and using Catalyst I in Table 2 to process the heavy feed oil in Table 1. The feedstock properties in Example 1 are shown in Table 1, and the light hydrocarbon A is used as the light hydrocarbon feedstock for the recycle light gasoline, which accounts for 30% of the heavy feedstock, half of which is the light gasoline produced by the device itself, and the other half is from other devices outside the device.

[0100] In the device provided in Example 1, the total length of the multi-diameter riser 11 is about 18 meters, the diameter of the multi-stage reaction pre-lifting section 11d is 0.25 meters, and the height is 1.5 meters, the diameter of the first reaction zone 11a is 0.30 meters, and the height is 4 meters; the diameter of the second reaction zone 11b is 1.2 meters, and the height is 7.6 meters, the diameter of the inner conveying pipe 13 is 0.30 meters, and the height is 2.5 meters; the diameter of the third reaction zone 11c is 0.30 meters, and the height is 4 meters, the longitudinal section of the joint part of the first reaction zone 11a and the second reaction zone 11b is an isosceles trapezoid, the angle between the side line of the isosceles trapezoid and the axis is 45°, and the height of the isosceles trapezoid is 0.45 meters; the longitudinal section of the joint part of the second reaction zone 11b and the third reaction zone 11c is an isosceles trapezoid, the angle between the side line of the isosceles trapezoid and the axis is 45°, and the height of the isosceles trapezoid is 0.45 meters; the distance between the inner conveying hole 13a and the inlet of the third reaction zone 11c is 1 meter, the ratio of the total area of the plurality of inner conveying holes 13a to the cross-sectional area of the inner conveying pipe 13 is 0.2:1, the distribution inner member 14 forms a cap-shaped distribution inner member, the ratio of the area of the end distribution plate 14c to the cross-sectional area of the second reaction zone 11b is 0.8:1, the ratio of the sum of the areas of the plurality of distribution holes 14a on the end distribution plate 14c to the vertical projection area of the end distribution plate 14c is 0.2:1, and the ratio of the sum of the areas of the distribution holes 14a on the distribution cylinder 14b to the cross-sectional area of the first reaction zone 11a is 2:1;

[0101] The total height of the cracking riser 21 is 13 meters, wherein the height of the cracking pre-lifting section 21b is 2 meters and the diameter is 0.12 meters, the height of the cracking reaction section 21a is 11 meters and the diameter is 0.15 meters, the height of the cracking stripping section 23a is 3 meters and the diameter is 0.35 meters, the height of the turbulent reaction section 23b is 1.5 meters and the diameter is 0.5 meters, the height of the cracking settling section 23c is 2.5 meters and the diameter is 1.3 meters, and the diameter of the cracking gas phase conveying pipe 24 is 0.2 meters.

[0102] The multi-stage reaction pre-lift gas A from the bottom of the multi-stage reaction pre-lift section 11d is mixed with the regenerated catalyst (catalyst I) directly from the catalyst heat remover 4 or the regenerated pipeline 6 of the regeneration unit 3 to go up. At the top of the multi-stage reaction pre-lift section 11d and the connection of the main body of the first reaction zone 11a, the heavy feedstock atomized by water vapor is fed into the multi-diameter lift pipe 11 through the heavy oil feeding system 7. The oil agent contacts and reacts in the first reaction zone 11a, goes up along the multi-diameter lift pipe 11, enters the second reaction zone 11b through the distribution inner member 14; due to the factors such as the decrease of the apparent velocity of the oil gas and the turning of the oil gas, the catalyst in the second reaction zone 11b is in the state of turbulent bed or dense phase conveying bed, which strengthens the contact of the oil agent; in the transition section of the second reaction zone 11b and the first reaction zone 11a, the quenching agent can be injected from the quenching oil gas unit 9, and the spent catalyst output from the catalyst outlet 25 at the bottom of the second reaction zone 11b is injected to supplement the catalyst activity in the second reaction zone 11b;

[0103] The pyrolysis pre-lift gas B is injected from the bottom of the pyrolysis pre-lift section 21b and mixed with the regenerated catalyst (catalyst I) directly from the catalyst heat exchanger 4 or the regeneration unit 3 to go up. The light feedstock (light hydrocarbon I) atomized by water vapor or directly mechanically atomized is introduced into the pyrolysis riser 21 through the pyrolysis feed unit 8 at the connection between the top of the pyrolysis pre-lift section 21b and the pyrolysis reaction section 21a. The light feedstock is contacted with the catalyst in the pyrolysis reaction section 21a and goes up. The reacted oil gas and the catalyst are separated at the bottom of the turbulent reaction section 23b through the pyrolysis distributor 22 at the top end of the pyrolysis reaction section 21a. The catalyst is stripped by steam from the steam stripping unit 10 at the bottom of the pyrolysis stripping section 23a and then sent into the second reaction zone 11b through the pyrolysis catalyst outlet 25. The reacted light hydrocarbon oil gas is introduced into the gas collection chamber at the top of the multi-stage reaction settling section 12 through the light hydrocarbon conveying pipe on the pyrolysis settling section 23c or directly into the multi-stage reaction settling section 12. The multi-stage reaction mixture in the second reaction zone 11b and the reacted spent catalyst in the pyrolysis riser 21 are fully mixed, contacted and redistributed, and then introduced into the third reaction zone 11c through the inner conveying pipe 13 which is reduced in diameter relative to the second reaction zone 11b. The reacted heavy feedstock oil gas is output from the top of the multi-stage reaction cyclone separator 12c and then introduced into the oil gas fractionating tower through the large transfer line at the bottom of the multi-stage reaction settling section 12. The catalyst containing coke after the reaction of the heavy feedstock is introduced into the multi-stage reaction stripping section 12a at the bottom of the multi-stage reaction settling section 12 through the conveying pipe at the lower part of the multi-stage reaction cyclone separator 12c. The spent catalyst after stripping by the multi-stage reaction stripping steam F is introduced into the regeneration unit 3 through the spent catalyst pipeline 5, contacted with the regeneration air C introduced into the bottom of the regeneration unit 3 to have an oxidation reaction, and then output from the top of the regeneration unit 3 as the regeneration flue gas D to further recover energy and be treated in the flue gas turbine. The high-temperature regenerated catalyst generated by burning off the coke is introduced into the catalyst heat exchanger 4 through the regenerated catalyst pipeline 6, and the low-temperature water vapor G is heated to become the high-temperature water vapor H. The regenerated catalyst after cooling is returned to the first reaction zone 11a and the bottom of the pyrolysis riser 21 through the regenerated catalyst pipeline 6 from the catalyst heat exchanger 4 for recycling.

[0104] The remaining operating conditions, the product distribution and the main properties of the gasoline are shown in Table 3.

[0105] Comparative Example 1

[0106] The catalytic cracking unit includes the multi-stage reaction unit 1 used in Example 1 and a conventional cracking unit, which uses a conventional riser, does not contain a cracking settler, and has a riser directly connected to a cyclone separator. The process conditions for producing an ultra-low olefin gasoline using Catalyst I in Table 2 to process the heavy feed oil in Table 1 are as follows. The parameters of the multi-stage reaction unit 1 are the same as those in Example 1, and the outlet temperature of the riser of the cracking unit is the same as the outlet temperature of the cracking riser 21 in Example 1.

[0107] The remaining operating conditions, the obtained product distribution, and the main properties of the gasoline are shown in Table 3.

[0108] Comparative Example 2

[0109] The catalytic cracking unit includes the multi-stage reaction unit 1 described in Example 1, does not have the cracking reaction unit 2, does not recycle light hydrocarbons, and uses Catalyst I in Table 2 to process the heavy feed oil in Table 1 to produce a low-olefin gasoline. The parameters of the multi-stage reaction unit 1 are the same as those in Example 1.

[0110] The remaining operating conditions, the obtained product distribution, and the main properties of the gasoline are shown in Table 3.

[0111] Comparative Example 3

[0112] The catalytic cracking unit includes the multi-stage reaction unit 1 used in Example 1, does not have the cracking reaction unit 2, does not recycle light hydrocarbons, and the diameter of the second reaction zone 11b is 0.9 meters. The multi-stage reaction unit 1 does not have the internal transport pipe 13 in the second reaction zone 11b, and the remaining parameters of the multi-stage reaction unit 1 are the same as those in Comparative Example 2. Catalyst I is used to process the heavy feed oil in Table 1 to produce a low-olefin gasoline.

[0113] The remaining operating conditions, the obtained product distribution, and the main properties of the gasoline are shown in Table 3.

[0114] Example 2

[0115] Compared with Example 1, the catalytic cracking unit used in this example has the same structure and parameters as those in Example 1, except that the distribution internal member 14 connecting the first reaction zone 11a and the second reaction zone 11b is a mushroom head distributor, Catalyst II in Table 2 is used, and the operating conditions are different. The properties of the feedstock in this example are shown in Table 1, wherein the light gasoline recycled as a light hydrocarbon II is used as a light feedstock, and the light gasoline accounts for 30% of the heavy feedstock, half of which is self-produced light gasoline from the device, and the other half is from other devices outside the device.

[0116] The remaining operating conditions, the obtained product distribution, and the main properties of the gasoline are shown in Table 3.

[0117] Comparative Example 4

[0118] The catalytic cracking unit included the multi-stage reaction unit 1 employed in Example 1 and a conventional cracking unit, which employed a conventional riser, did not contain a cracking disengager, and had the riser directly connected to a cyclone separator, and processed the heavy feed oil in Table 1 using Catalyst II in Table 2 in a mode for maximizing the production of cracking gas. The parameters of the multi-stage reaction unit 1 were the same as in Example 2, and the outlet temperature of the riser of the cracking unit was the same as the outlet temperature of the cracking riser 21 in Example 1.

[0119] The remaining operating conditions, the product distribution obtained, and the main properties of the gasoline are shown in Table 3.

[0120] Comparative Example 5

[0121] The catalytic cracking unit included the multi-stage reaction unit 1 employed in Example 1, did not have the cracking reaction unit 2, did not recycle light hydrocarbons, and processed the heavy feed oil in Table 1 using Catalyst II in Table 2 in a mode for maximizing the production of cracking gas. The parameters of the multi-stage reaction unit 1 were the same as in Example 2.

[0122] The remaining operating conditions, the product distribution obtained, and the main properties of the gasoline are shown in Table 3.

[0123] Comparative Example 6

[0124] The catalytic cracking unit included the multi-stage reaction unit 1 employed in Example 1, did not have the cracking reaction unit 2, did not recycle light hydrocarbons, and the diameter of the second reaction zone 11b was 0.9 m, and the second reaction zone 11b did not have the internal transport pipe 13, and the remaining parameters of the multi-stage reaction unit 1 were the same as in Comparative Example 5.

[0125] The remaining operating conditions, the product distribution obtained, and the main properties of the gasoline are shown in Table 3.

[0126] Table 1 Feed Properties

[0127] Item Heavy feedstock Light hydrocarbons I Light hydrocarbons II Density (20°C) kg / m 3 ]] 0.8954 0.7121 0.7243 Carbon residue, wt% 2 —— —— Elemental analysis Carbon content, wt% 86.85 86.46 86.67 Hydrogen content, wt% 12.58 13.46 13.22 Sulfur content, wt% 0.37 —— —— Nitrogen content, wt% 0.27 —— —— Hydrocarbon group composition analysis Saturates, wt% 68.24 —— —— Aromatics, wt% 20.09 —— —— Gel, wt% 10.72 —— —— Asphaltene, wt% 0.95 —— —— Ni content, pg / g 4.3 —— —— V content, pg / g 0.3 —— —— PONA, wt% P —— 6 4 I —— 26 13 O —— 49 62 N —— 4 3 A —— 15 18

[0128] Table 2 Catalyst Properties

[0129] Primary catalyst Catalyst I Catalyst II Zeolite type ReHY primary ZSM-5 primary Chemical composition, wt% Alumina 46.4 52.1 Sodium oxide 0.22 0.15 Screening composition, wt% 0-40 pm 20.23 25.54 40-80 pm 52.12 48.05 > 110 pm —— 26.41 Specific surface area / m 2 .g -1 ]]> 165 210 Deposition density / g.cm -3 ]] 0.76 0.79 Apparent density / g.cm -3 ]] 0.71 0.75 Micro-activity, % 68 58 Screening composition, wt% 0.38 0.28

[0130] Table 3 Operating Conditions and Product Distribution

[0131]

[0132] As can be seen from Table 3, the four of Example 1, Comparative Example 1, Comparative Example 2 and Comparative Example 3 are all production of ultra-low olefin gasoline mode, Example 1 and Comparative Example 1 recycle 30% of light hydrocarbon I, half of which comes from the outside of the device of light gasoline rich in olefins; Comparative Example 2 and Comparative Example 3 do not recycle gasoline; the gasoline olefin of Example 1 is reduced by 2.6, 3.6 and 6.4 percentage points respectively relative to Comparative Example 1, Comparative Example 2 and Comparative Example 3, and the propylene yield is increased by 0.5, 0.7 and 1.1 percentage points respectively; indicating that the device and method provided by the application can significantly reduce the content of gasoline olefin and moderately increase the propylene yield.

[0133] The four of Example 2, Comparative Example 4, Comparative Example 5 and Comparative Example 6 are all production of cracked gas operation mode, Example 2 and Comparative Example 4 recycle 30% of light hydrocarbon II, half of which comes from the outside of the device of light gasoline rich in olefins; Comparative Example 5 and Comparative Example 6 do not recycle gasoline; the gasoline olefin of Example 2 is reduced by 3.3, 11.2 and 13.8 percentage points respectively relative to Comparative Example 4, Comparative Example 5 and Comparative Example 6, and the propylene yield is increased by 1.3, 2.6 and 4.5 percentage points respectively; indicating that the device and method provided by the application can significantly reduce the content of gasoline olefin and increase the propylene yield.

[0134] The device and method provided by the application can promote the reduction of gasoline olefin of the entire refinery gasoline pool, and the cracked gas yield is significantly improved, but the cracked gas yield or output is significantly improved for the entire refinery.

[0135] The preferred embodiments of the application are described in detail above with reference to the drawings, but the application is not limited to the specific details in the above-described embodiments, and various simple modifications can be made to the technical solutions of the application within the technical concept of the application, and these simple modifications all belong to the protection scope of the application.

[0136] In addition, it should be noted that the various specific technical features described in the above specific embodiments can be combined in any appropriate manner without contradiction, and in order to avoid unnecessary repetition, the application will not further describe various possible combinations. In addition, various different embodiments of the application can also be combined in any manner, as long as it does not deviate from the technical concept of the application, it should also be considered as disclosed by the application.

Claims

1. An apparatus for catalytic cracking, characterized in that, The device comprises a multi-stage reaction unit (1) and a cracking reaction unit (2), the multi-stage reaction unit (1) comprises a multi-diameter riser (11) and a multi-stage reaction settler (12), and the cracking reaction unit (2) comprises a cracking riser (21) and a cracking settler (23); the multi-diameter riser (11) comprises a first reaction zone (11a), a second reaction zone (11b) and a third reaction zone (11c) connected in series along the length direction of the multi-diameter riser (11), the outlet of the third reaction zone (11c) is communicated with the multi-stage reaction settler (12), the inner diameter of the second reaction zone (11b) is larger than that of the first reaction zone (11a) and the third reaction zone (11c), and an inner conveying pipe (13) extending to the inside of the second reaction zone (11b) is arranged at the connection between the third reaction zone (11c) and the second reaction zone (11b); The cracking settler (23) comprises a cracking stripping section (23a), a turbulent reaction section (23b) and a cracking settling section (23c) arranged in series along the length direction of the cracking settler (23), and the outlet of the cracking riser (21) is located in the turbulent reaction section (23b); the cracking stripping section (23a) is provided with a cracking catalyst outlet (25) communicated with the second reaction zone (11b); The second reaction zone (11b) is provided with a distribution inner member (14) connected with the first reaction zone (11a), and a plurality of distribution holes (14a) are arranged on the distribution inner member (14); the distribution inner member (14) comprises a distribution cylinder (14b) connected with the first reaction zone (11a) and an end distribution plate (14c) connected with the distribution cylinder (14b), and the distribution holes (14a) are arranged on the distribution cylinder (14b) and the end distribution plate (14c); and the end distribution plate (14c) is located at one end of the distribution cylinder (14b) away from the first reaction zone (11a).

2. The apparatus of claim 1, wherein, The ratio of the inner conveying pipe (13) to the inner diameter of the third reaction zone (11c) is 0.9-1.2:1, and the ratio of the inner conveying pipe (13) to the length of the second reaction zone (11b) is 0.15-0.8:

1.

3. The apparatus of claim 1, wherein, The ratio of the inner diameters of the first reaction zone (11a), the second reaction zone (11b) and the third reaction zone (11c) is 1:2-5:0.7-1.5, and the ratio of the lengths is 1:0.3-2:0.5-2; The ratio of the inner diameters of the turbulent reaction section (23b), the cracking stripping section (23a) and the cracking settling section (23c) is 1:0.4-0.8:2.5-5, and the ratio of the lengths is 1:1.5-3:1.5-4; The ratio of the lengths of the multi-diameter riser (11) and the cracking riser (21) is 1:0.5-1.

2.

4. The apparatus of claim 1, wherein, At least one inner conveying hole (13a) is arranged on the side wall of the inner conveying pipe (13), and the distance between the inner conveying hole (13a) and the inlet of the third reaction zone (11c) is 0.5-2 m.

5. The apparatus of claim 4, wherein, The ratio of the total area of the at least one inner delivery hole (13a) to the cross-sectional area of the inner delivery pipe (13) is 0.05-0.3:

1.

6. The apparatus of claim 1, wherein, The ratio of the sum of the areas of the distribution holes (14a) on the distribution cylinder (14b) to the cross-sectional area of the first reaction zone (11a) is 0.6-4:

1. The ratio of the sum of the areas of the distribution holes (14a) on the end distribution plate (14c) to the vertical projection area of the end distribution plate (14c) is 0.1-0.3:

1.

7. The apparatus of claim 1, wherein, The side channel (14d) extending outward from the distribution cylinder (14b) is provided at the distribution hole (14a) on the distribution cylinder (14b), and the opening cross section of the side channel (14d) away from the distribution cylinder (14b) is a slope towards the first reaction zone (11a).

8. The apparatus of claim 1, wherein, The ratio of the area of the end distribution plate (14c) to the cross-sectional area of the second reaction zone (11b) is 0.7-0.85:

1.

9. The apparatus of any one of claims 1 to 5, wherein, The first reaction zone (11a), the second reaction zone (11b), the third reaction zone (11c), and the inner delivery pipe (13) are coaxially arranged, and the cracking catalyst outlet (25) is located at the bottom of the cracking stripping section (23a) and communicates with the bottom of the second reaction zone (11b).

10. The apparatus of any one of claims 1 to 5, wherein, The multi-diameter riser (11) further comprises a multi-stage reaction pre-lifting section (11d) connected to the inlet of the first reaction zone (11a), the cracking riser (21) comprises a cracking pre-lifting section (21b) and a cracking reaction section (21a) connected in series along the length direction, the outlet of the cracking reaction section (21a) is located at one end of the turbulent reaction section (23b) close to the cracking stripping section (23a), the transition section between the multi-stage reaction pre-lifting section (11d) and the first reaction zone (11a) communicates with the multi-stage reaction feeding unit (7), and the transition section between the cracking pre-lifting section (21b) and the cracking reaction section (21a) communicates with the cracking feeding unit (8).

11. The apparatus of claim 10, wherein, The outlet of the cracking reaction section (21a) is provided with a cracking distributor (22), and the gas phase outlet of the cracking settling section (23c) communicates with the multi-stage reaction settler (12).

12. The apparatus of any one of claims 1 to 5, wherein, The device further comprises a regeneration unit (3), and the multi-stage reaction settler (12) is provided with a multi-stage reaction catalyst outlet (15) communicating with the inlet of the regeneration unit (3), and the regeneration catalyst outlet (31) of the regeneration unit (3) communicates with the multi-diameter riser (11) and / or the cracking riser (21).

13. A process for catalytic cracking, characterized by The device of any one of claims 1-12 is used, and the method comprises the following steps: The device of any one of claims 1-12 is used, and the method comprises the following steps: The multi-stage reaction mixture of the heavy feedstock mixed with the multi-stage reaction catalyst is input from the inlet of the first reaction zone (11a) and sequentially enters the first reaction zone (11a), the second reaction zone (11b), and then the third reaction zone (11c) from the inner conveying pipe (13) to perform multi-stage catalytic reaction to obtain a multi-stage reaction product, which is separated by the multi-stage reaction settler (12) to obtain a multi-stage reaction oil and gas product and a multi-stage reaction spent catalyst; The cracking mixture of the light feedstock mixed with the cracking catalyst is input from the inlet of the cracking riser (21), and the cracking catalytic reaction is performed in the cracking riser (21) to obtain a cracking reaction product, which is subjected to turbulent reaction in the turbulent reaction section (23b) and then subjected to cracking separation in the cracking settling section (23c) and cracking stripping in the cracking stripping section (23a) to obtain a cracking oil and gas product and a cracking spent catalyst; The cracking spent catalyst is input from the cracking catalyst outlet (25) into the second reaction zone (11b) and mixed with the multi-stage reaction mixture.

14. The method of claim 13, wherein, The inlet temperature of the inner conveying pipe (13) is 510-540℃, and the outlet temperature of the cracking riser (21) is 540-620℃.

15. The method of claim 13, wherein, The inlet temperature of the inner conveying pipe (13) is 550-640℃, and the outlet temperature of the cracking riser (21) is 560-660℃.

16. The method according to any one of claims 13 to 15, characterized in that, The residence time of the multi-stage reaction mixture in the first reaction zone (11a) is 0.8-2s, in the second reaction zone (11b) is 5-15s, and in the third reaction zone (11c) is 0.5-1.5s; The residence time of the cracking mixture in the cracking riser (21) is 0.8-3.5s, and in the turbulent reaction section (23b) is 3-13s.

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