CN111423904B

CN111423904B - Catalytic cracking process and system

Info

Publication number: CN111423904B
Application number: CN201910020511.2A
Authority: CN
Inventors: 沙有鑫; 朱根权; 杨超; 成晓洁; 马文明
Original assignee: Sinopec Research Institute of Petroleum Processing; China Petroleum and Chemical Corp
Current assignee: Sinopec Research Institute of Petroleum Processing; China Petroleum and Chemical Corp
Priority date: 2019-01-09
Filing date: 2019-01-09
Publication date: 2023-10-13
Anticipated expiration: 2039-01-09
Also published as: CN111423904A

Abstract

The invention relates to the field of catalytic cracking, and discloses a catalytic cracking process and a catalytic cracking system. The process comprises the following steps: in a first downlink tube reactor, the heavy raw material is in contact reaction with a catalytic cracking catalyst to obtain a first reaction product and a spent catalyst; sending the first reaction product and the spent catalyst into a settling section at the upper part of a fluidized bed reactor for gas-solid separation, and sending the spent catalyst obtained by separation into the fluidized bed reactor; in the second downer reactor, the light raw material is contacted and reacted with a catalytic cracking catalyst to obtain a second reaction product and a spent catalyst; feeding the second reaction product and the spent catalyst into a fluidized bed reactor to contact and react with a catalytic cracking catalyst to obtain a third reaction product and the spent catalyst; the spent catalyst from the fluidized bed reactor is regenerated. The process and the system provided by the invention can improve the quality of the diesel oil while improving the yield of the low-carbon olefin and the diesel oil, increase the ratio of the low-carbon olefin to the yield of the dry gas, and optimize the distribution of the products.

Description

Catalytic cracking process and system

Technical Field

The invention relates to a catalytic cracking process and a catalytic cracking system.

Background

Small molecular olefins such as ethylene, propylene and butene are the most basic organic synthetic materials. At present, the main production process of small molecular olefins in the world is a steam cracking process, but high-temperature cracking Jie Lu is easy to coke, so the process basically takes light oil as raw materials, such as natural gas, naphtha and light diesel oil, and can also take hydrocracking tail oil as raw materials. At present, the trend of crude oil heaviness and poor quality in China is more obvious, the yield of light oil such as naphtha is lower, and the contradiction between raw material supply and demand of a steam cracking process and a catalytic reforming process is increasingly serious. Since the mid-eighties of the twentieth century, the institute of petrochemical science, the chinese petrochemical company limited, began to conduct research on the catalytic cracking family technology for producing low-carbon olefins from heavy oil, and successfully developed the catalytic cracking (DCC, USP4980053 and USP 5670037) technology for maximum production of propylene and the catalytic thermal cracking (CPP, USP 6210562) technology for maximum production of ethylene. So far, the two technologies mainly adopt a reactor structure of a single riser reactor or a single riser reactor combined dense phase fluidized bed, and the dry gas and coke yield is higher while the yield of the low-carbon olefin is improved.

In recent years, technologies for heavy oil cracking to produce low-carbon olefins by using multiple reactors have been attracting great attention, and these technologies are all to select different reactors for different raw materials, including an uplink reactor, a downlink reactor and a fluidized bed reactor, and even select different catalysts, so as to ensure that various raw materials react in a reaction environment more suitable for the characteristics of the raw materials.

For example, CN101074392a discloses a method for producing propylene and high-quality gasoline and diesel oil by two-stage catalytic cracking, which mainly uses two-stage riser catalytic cracking technology, adopts a catalyst rich in shape-selective zeolite, uses heavy petroleum hydrocarbon or various animal and vegetable oils rich in hydrocarbon as raw materials, performs optimal combination of feeding modes for reactant materials with different properties, and controls appropriate reaction conditions of different materials, so as to achieve the purposes of improving propylene yield, considering light oil yield and quality, and inhibiting generation of dry gas and coke. The method specifically provides that the feed of the first section of lifting pipe is fresh heavy raw oil, and the lower part or the bottom of the first section of lifting pipe can be fed with light hydrocarbon raw materials; the second stage riser is fed with gasoline and cycle oil with high olefin content, and can be fed in layers or mixed, and the lower part or the bottom of the second stage riser can be fed with other light hydrocarbon raw materials.

In another example, CN101045667a proposes a catalytic conversion method for improving the yield of low-carbon olefins, in which a hydrocarbon oil raw material is injected into a downlink reactor through a raw material nozzle, contacts with a regenerated catalyst and an optional carbon deposition catalyst, separates a cracked product from a spent catalyst, and after the cracked product is separated, the low-carbon olefins are obtained, at least a part of the rest of the products are introduced into a riser reactor to contact with a regenerator for reaction, and the oil gas is separated from the spent catalyst. According to the method, the generated low-carbon olefin is separated from the spent agent in time, so that secondary reaction of the low-carbon olefin is effectively inhibited, and the yield of the low-carbon olefin is improved. However, it is difficult to satisfy the conversion rate of heavy oil and light hydrocarbon by only the down reactor and the riser reactor, and the maximization of the yield of low-carbon olefin is not achieved, and it can be seen from the disclosed examples that the ratio of the yield of low-carbon olefin to the yield of dry gas is below 3, the raw materials are not fully utilized, and the low-value product is high.

For another example, CN101210191a proposes a catalytic cracking method in which a down-flow reactor and a riser reactor are connected in series. The method comprises the steps of enabling preheated raw oil to enter a descending reactor to contact with a high-temperature regenerated catalyst from a regenerator, vaporizing and performing a cracking reaction, enabling oil gas from an outlet of the descending reactor to enter a riser reactor for continuous reaction, introducing another regenerated catalyst from an inlet of the riser reactor, and enabling the oil gas from an outlet of the riser reactor to enter a sedimentation separator for separation. According to different target products, a catalyst different from a downstream reactor can be adopted in the riser reactor, so that the gasoline yield can be improved, and the product quality can be improved. However, the catalytic cracking method employing the downstream reactor and the riser reactor connected in series inevitably causes heavy oil to interfere with the reaction of light oil, so that light hydrocarbon is not further converted, and light olefin may undergo further reaction, thus resulting in a reduction in the yield of low carbon olefin.

For another example, CN102690682a proposes a catalytic cracking process for producing propylene, which comprises: the heavy raw material and a first catalytic cracking catalyst taking Y-type zeolite as a main active component are contacted and reacted in a first riser, oil gas after the reaction is separated from the catalyst, the oil gas is introduced into a product separation system, the catalyst is stripped by a first stripper and then is introduced into a first riser reactor for regeneration in the process of generating gas, and the regenerated catalyst is introduced into the first riser reactor for recycling. The light hydrocarbon and the second catalytic cracking catalyst which takes the shape-selective zeolite with the average pore diameter smaller than 0.7nm as the main active component are in contact reaction in the second riser reactor, the obtained oil gas is introduced into a fluidized bed reactor connected in series with the second riser reactor for reaction, the oil gas after the fluidized bed reaction is introduced into a product separation system, the catalyst is introduced into a second regenerator for regeneration after being stripped by a second stripper, and the regenerated catalyst is introduced into the second riser reactor for recycling. The stripper of the catalytic cracking device is divided into two independent stripping areas by a baffle plate, and the two stripping areas and the two lifting pipes form two independent reaction, stripping and regeneration routes respectively.

Based on the prior art, a new catalytic cracking process and system capable of improving the yield of the low-carbon olefin and optimizing the distribution of the product are still to be developed.

Disclosure of Invention

The invention aims to provide a novel catalytic cracking process and system, which can improve the quality of diesel oil, increase the ratio of low-carbon olefin to dry gas yield and optimize the product distribution while improving the yield of low-carbon olefin and diesel oil.

The inventor of the invention is based on a combined reactor formed by a first downpipe reactor, a fluidized bed reactor and a second downpipe reactor, adopts the same catalytic cracking catalyst in the first downpipe reactor, the fluidized bed reactor and the second downpipe reactor through optimization of a process scheme, catalytically cracks heavy raw materials into reaction products containing low-carbon olefin in the first downpipe reactor, and continuously reacts in the fluidized bed reactor after the light raw materials react in the second downpipe reactor, so that the catalytic cracking of different feeds in a proper reactor is realized, the heavy oil conversion rate is effectively improved, the light raw materials are promoted to crack again, and the ratio of low-carbon olefin to dry gas yield is remarkably increased.

In order to achieve the above object, the present invention provides, in one aspect, a catalytic cracking process, wherein the process comprises:

(1) In a first downlink tube reactor, contacting heavy raw materials with a catalytic cracking catalyst to perform catalytic cracking reaction to obtain a first reaction product and a spent catalyst;

(2) Sending the first reaction product obtained in the step (1) and the spent catalyst into a settling section at the upper part of a fluidized bed reactor for gas-solid separation, sending the separated first reaction product out of the fluidized bed reactor, and sending the separated spent catalyst into the fluidized bed reactor;

(3) In the second downer reactor, the light raw material contacts with a catalytic cracking catalyst to carry out catalytic cracking reaction to obtain a second reaction product and a spent catalyst;

(4) Sending the second reaction product and the spent catalyst in the step (3) into a fluidized bed reactor, and contacting the fluidized bed reactor with a catalytic cracking catalyst to perform catalytic cracking reaction to obtain a third reaction product and the spent catalyst;

(5) In the regenerator, the spent catalyst from the fluidized bed reactor is regenerated to obtain a regenerated catalyst.

Preferably, the process further comprises: separating the first reaction product from the third reaction product to obtain dry gas, liquefied gas, gasoline, diesel oil and slurry oil; feeding the separated liquefied gas and/or gasoline and/or diesel oil serving as the light raw material into the second downer reactor to be contacted with a catalytic cracking catalyst for catalytic cracking reaction; the method comprises the steps of,

the process further comprises: sending the separated slurry oil into the second downgoing pipe reactor to contact with a catalytic cracking catalyst for catalytic cracking reaction;

Preferably, the weight ratio of gasoline fed to the second downpipe reactor to heavy feedstock fed to the first downpipe reactor is from (0.05 to 0.3): 1, more preferably from (0.1 to 0.2): 1;

preferably, the weight ratio of diesel fuel fed to the second downpipe reactor to heavy feedstock fed to the first downpipe reactor is (0.02-0.3): 1, more preferably (0.05-0.2): 1;

preferably, the weight ratio of slurry oil fed to the second downpipe reactor to heavy feedstock fed to the first downpipe reactor is from (0.01 to 0.2): 1, more preferably from (0.05 to 0.15): 1.

In a second aspect, the present invention provides a catalytic cracking system, wherein the system comprises a first downer reactor, a fluidized bed reactor, a regenerator, and a second downer reactor; the fluidized bed reactor comprises a sedimentation section, a fluidized bed reaction section and a stripping section from top to bottom in sequence; the first downer reactor is communicated with a settling section of the fluidized bed reactor; the second downer reactor is communicated with a fluidized bed reaction section of the fluidized bed reactor; the regenerator is respectively communicated with the first downpipe reactor, the fluidized bed reactor and the second downpipe reactor.

According to the invention, the first downpipe reactor is arranged along the flow direction of the heavy raw material, and then the first reaction product obtained after the reaction in the first downpipe reactor and the spent catalyst of carbon deposit are subjected to high-efficiency gas-solid separation in the settling section of the fluidized bed reactor, so that the heavy raw material can be effectively cracked into propylene and gasoline, and the generated low-carbon olefin can be directly removed from the product separation device without further reaction. In addition, by utilizing the first downer reactor, the back mixing phenomenon of the catalyst in the traditional riser reactor can be avoided to the greatest extent, and the activity of the catalyst is improved. Preferably, after the first reaction product of the heavy raw material reacted in the first downer reactor is subjected to product separation, at least part of separated slurry oil is sent to the second downer reactor and then is continuously reacted in the fluidized bed reactor, so that the reaction process of effectively cracking the heavy raw material (slurry oil) into light olefins and gasoline in the fluidized bed reactor is further enhanced.

The invention leads the gasoline and/or C rich in olefin to be ₄ Hydrocarbon and/or diesel oil is introduced into the second downer reactor as light raw material, the carbon deposit amount of the catalyst in the reaction process of the light raw material is small, the back mixing phenomenon of the catalyst in the traditional riser reactor can be avoided to the greatest extent, and the activity of the catalyst is improved. The spent catalyst after the reaction has higher activity and can be introduced into a fluidized bed reactor to continuously contact with light raw materials and promote lightAnd (3) reacting the raw materials. The high-temperature regenerant from the regenerator is supplemented to the inlet of the fluidized bed reactor to regulate and control the causticity (including reaction temperature and agent-oil ratio) of the fluidized bed reactor.

The invention preferably leads the diesel oil fraction obtained by separating the first reaction product of heavy raw materials after the reaction of the first downer reactor to the second downer reactor together with the light raw materials, and/or leads the liquefied gas/gasoline/diesel oil fraction obtained by separating the third reaction product of the light raw materials after the reaction of the second downer reactor and the fluidized bed reactor to the second downer reactor together with the light raw materials, thereby flexibly controlling the re-catalytic cracking reaction of the diesel oil fraction, further improving the yield of low-carbon olefin and simultaneously improving the quality of diesel oil.

The invention preferably introduces the slurry oil separated from the heavy raw material after the reaction in the second downer reactor into the second downer reactor to contact with the high-activity regenerant, thereby effectively improving the conversion rate of the heavy raw material.

Drawings

FIG. 1 is a schematic flow diagram of one embodiment of the process of the present invention, including a schematic structural diagram of one embodiment of the system of the present invention.

Description of the reference numerals

1 first catalyst tank 2 first downer reactor 3 fluidized bed reactor

Inclined tube for spent agent in 4 sedimentation section 5 stripping section 6

7 regenerator 8 first regeneration chute 9 second downer reactor

10 second catalyst tank 11 second regeneration inclined tube 12 product separation device

13 third regeneration chute 14 heavy raw material line 15 first atomized water vapor line

16 stripping steam line 17 first lifting medium line 18 returns to the slurry line

19 second atomized water vapor pipeline 20 light raw material pipeline 21 oil gas pipeline

22 regenerated flue gas pipeline 23 gaseous hydrocarbon pipeline 24 gasoline pipeline

25 diesel oil line 26 light cycle oil line 27 separation slurry oil line

28 second lifting medium line 29 oxygen-containing gas line

Detailed Description

The endpoints and any values of the ranges disclosed herein are not limited to the precise range or value, and are understood to encompass values approaching those ranges or values. For numerical ranges, one or more new numerical ranges may be found between the endpoints of each range, between the endpoint of each range and the individual point value, and between the individual point value, in combination with each other, and are to be considered as specifically disclosed herein.

According to the invention, the catalytic cracking process comprises the following steps:

As shown in fig. 1, the catalytic cracking process includes:

sending heavy raw materials into the upper part of a first downlink tube reactor 2 to contact with a catalytic cracking catalyst from the top of the first downlink tube reactor 2 and carrying out catalytic cracking reaction from top to bottom to obtain a first reaction product and a spent catalyst;

The obtained first reaction product and the spent catalyst are sent into a sedimentation section 4 at the upper part of a fluidized bed reactor 3 for gas-solid separation, and the spent catalyst enters the fluidized bed reactor 3;

the light raw materials are sent to the top of a second downgoing pipe reactor 9 to contact with a catalytic cracking catalyst and carry out cracking reaction from top to bottom to obtain a second reaction product and a spent catalyst;

the obtained second reaction product and the spent catalyst are sent into a fluidized bed reactor 3 to be contacted with a catalytic cracking catalyst and subjected to catalytic cracking reaction, so as to obtain a third reaction product and the spent catalyst;

the spent catalyst from the fluidized bed reactor 3 is fed into a regenerator 7 for regeneration to obtain regenerated catalyst.

In the catalytic cracking process, the same catalytic cracking catalyst is adopted in the first downlink pipe reactor, the fluidized bed reactor and the second downlink pipe reactor, the heavy raw material is catalytically cracked into a reaction product containing low-carbon olefin in the first downlink pipe reactor, and the reaction product containing low-carbon olefin after the light raw material is reacted in the second downlink pipe reactor is continuously reacted in the fluidized bed reactor, so that different feeds are subjected to catalytic cracking in the proper reactors. Preferably, the product of the heavy raw material after the catalytic cracking reaction is separated and then is introduced into a second downer reactor as a light raw material for reaction, so that the heavy oil conversion rate can be effectively improved, the light raw material is promoted to be cracked again, and the ratio of the yield of the low-carbon olefin to the yield of the dry gas is obviously increased.

According to the invention, the light raw materials are subjected to catalytic pyrolysis in the second downer reactor 9 and the fluidized bed reactor 3, and the heavy raw materials are subjected to catalytic pyrolysis in the first downer reactor 2, so that different raw materials can be subjected to catalytic pyrolysis respectively, the selectivity of target products is improved, the second reaction product with lower carbon content obtained by the light raw material pyrolysis reaction can be sent to the fluidized bed reactor 3 again for pyrolysis, and the regenerated catalyst is sent to the fluidized bed reactor to improve the average activity of the catalytic pyrolysis catalyst, and the conversion rate of the catalytic pyrolysis of the fluidized bed reactor 3 is increased.

According to the invention, the process further comprises: and carrying out product separation on the first reaction product and the third reaction product to obtain dry gas, liquefied gas, gasoline, diesel oil and slurry oil. In order to convert light hydrocarbon in the catalytic cracking product, the process further comprises feeding at least part of liquefied gas and/or gasoline and/or diesel oil obtained by separation into the second downpipe reactor as the light raw material to be contacted with a catalytic cracking catalyst for catalytic cracking reaction. The invention preferably leads the diesel oil fraction obtained by separating the first reaction product of heavy raw materials after the reaction of the first downer reactor to the second downer reactor together with the light raw materials, and/or leads the liquefied gas/gasoline/diesel oil fraction obtained by separating the third reaction product of the light raw materials after the reaction of the second downer reactor and the fluidized bed reactor to the second downer reactor together with the light raw materials, thereby flexibly controlling the re-catalytic cracking reaction of the diesel oil fraction and the like, further improving the yield of low-carbon olefin and simultaneously improving the quality of diesel oil.

According to the invention, in order to increase the conversion of heavy oil, the process further comprises: and (3) sending at least part of the separated slurry oil into the second downer reactor to be contacted with a catalytic cracking catalyst for catalytic cracking reaction.

According to the present invention, the spent catalyst from the fluidized bed reactor is derived from the spent catalyst after the contact reaction with the heavy feedstock in the first downpipe reactor, the spent catalyst after the contact reaction with the light feedstock in the second downpipe reactor and after the continuous reaction in the fluidized bed reactor, and the spent catalyst after the reaction of the catalyst entering the fluidized bed reactor and the light feedstock are replenished, respectively.

According to the invention, the regeneration of the spent catalyst is known to the person skilled in the art. Thus, in order to be able to regenerate the spent catalyst from the reaction of the first downpipe reactor, the second downpipe reactor and the fluidized bed reactor together, the catalytic cracking process further comprises: and (3) carrying out gas-solid separation on the third reaction product and the catalyst to be regenerated through a settling section 4 at the upper part of the fluidized bed reactor 3, sending the separated third reaction product out of the settling section 4 of the fluidized bed reactor 3, and allowing the separated catalyst to be regenerated to enter the fluidized bed reactor.

According to the invention, the process further comprises: a step of stripping before regenerating the spent catalyst from the fluidized bed reactor. The step of stripping the spent catalyst is well known to the person skilled in the art, for example, contacting the spent catalyst with atomized water vapor, the specific stripping conditions being well known to the person skilled in the art. Preferably, the stripping is performed in a stripping section in the lower part of the fluidized bed reactor in order not to add additional equipment. As shown in fig. 1, the first reaction product and the spent catalyst in the step (1) are sent to a settling section 4 at the upper part of a fluidized bed reactor 3 for gas-solid separation, the separated first reaction product is sent out of the fluidized bed reactor 3, and the separated spent catalyst is sent to a stripping section 5 at the lower part of the fluidized bed reactor 3 for stripping and then is sent to a regenerator 7; and carrying out gas-solid separation on the third reaction product and the spent catalyst through a settling section 4 at the upper part of the fluidized bed reactor 3, sending the separated third reaction product out of the settling section 4 of the fluidized bed reactor 3, and sending the separated spent catalyst into a stripping section 5 at the lower part of the fluidized bed reactor 3 for stripping and then into a regenerator 7.

According to the invention, the process further comprises: the regenerated catalyst obtained in the step (5) is used as the catalytic cracking catalyst in the step (1) and/or the step (3) and/or the step (4). The regenerated catalyst is continuously recycled to the steps, so that the whole system can continuously run, the cost can be saved, and additional catalyst regeneration equipment is not required to be built. As shown in fig. 1, the regenerated catalyst obtained is fed to the top of the first downpipe reactor 2 (first catalyst tank 1), to the top of the second downpipe reactor 9 (second catalyst tank 10), and to the bed reactor portion of the fluidized bed reactor 3. In order to promote the catalytic cracking reaction, the regenerated catalyst for high yield of low carbon olefin, which is fed into the first downpipe reactor for catalytic cracking reaction, the second downpipe reactor for catalytic cracking reaction and the fluidized bed reactor for catalytic cracking reaction, is uncooled catalyst, i.e. the temperature is 500-900 deg.c, preferably 600-800 deg.c.

According to the invention, different weights of regenerated catalyst can be fed selectively from said regenerator 7 into the fluidized bed reactor 3, the first downpipe reactor 2 and the second downpipe reactor 9, depending on the different feeds to the different reactors. Preferably, more than 0 to less than 100 wt.%, preferably 10-70 wt.% of regenerated catalyst is fed to the first downer reactor 2 of step (1), more than 0 to less than 100 wt.%, preferably 20-60 wt.% of regenerated catalyst is fed to the fluidized bed reactor 3 of step (4), and 0 to less than 100 wt.%, preferably 10-40 wt.% of regenerated catalyst is fed to the second downer reactor 9 of step (3), based on the total weight of regenerated catalyst exiting the regenerator per unit time, to better meet the catalyst to oil ratio in each reactor.

According to the invention, the yield of the low-carbon olefin can be further improved and the distribution of reaction products can be optimized by combining different feeds of different reactors and preferably further optimizing the reaction conditions of different reactors.

According to the present invention, in the first downpipe reactor, the conditions under which the heavy feedstock is contacted with the catalytic cracking catalyst to perform the catalytic cracking reaction generally include a reaction temperature and a reaction time. In order to allow the heavy raw material to be more fully contacted with the catalyst in the first downlink pipe reactor to carry out catalytic cracking reaction, the conditions of the catalytic cracking reaction include: the reaction temperature (outlet temperature at the bottom of the first downpipe reactor 2) is 510-690 ℃, preferably 520-650 ℃; the ratio of the agent to the oil is 5-20, preferably 7-18; the reaction time is 0.5 to 8 seconds, preferably 1.5 to 4 seconds. Wherein the catalyst-to-oil ratio refers to the mass ratio of the catalytic cracking catalyst to the heavy raw material. The atomized water vapor of the heavy raw material feed accounts for 2-50 wt%, preferably 5-15 wt%, of the total weight of the heavy raw material and the atomized water vapor.

In the second downpipe reactor, the conditions under which the light feedstock is contacted with the catalytic cracking catalyst to perform the catalytic cracking reaction generally include a reaction temperature and a reaction time. In order to allow the light feedstock to more fully contact the catalyst in the second downpipe reactor for a catalytic cracking reaction, the conditions of the catalytic cracking reaction include: the reaction temperature (outlet temperature at the bottom of the second downpipe reactor 9) is 520-720 ℃, preferably 530-700 ℃; the ratio of the agent to the oil is 8-26, preferably 10-24; the reaction time is 1 to 10 seconds, preferably 2 to 7 seconds. Wherein, the catalyst-to-oil ratio refers to the weight ratio of the catalytic cracking catalyst to the light raw material. The light feedstock feed atomized water vapor comprises from 2 to 50 wt%, preferably from 5 to 15 wt%, of the total weight of the light feedstock, optional slurry oil and atomized water vapor.

According to the invention, the second reaction product after the reaction in the second downpipe reactor and the spent catalyst are further reacted in the fluidized bed reactor, so that the further conversion of light hydrocarbons is promoted. In order to make the light hydrocarbon more fully contact with a spent catalyst with certain catalytic cracking activity and a complementary fresh catalytic cracking catalyst in a fluidized bed reactor for carrying out catalytic cracking reaction, the conditions of the catalytic cracking reaction include: the reaction temperature is 480-650 ℃, preferably 500-640 ℃; a weight hourly space velocity of from 1 to 35, preferably from 2 to 33, per hour; the ratio of the agent to the oil is 6-20, preferably 7-18; the reaction pressure (absolute pressure, outlet pressure) is 0.15 to 0.35MPa, preferably 0.2 to 0.35MPa. Wherein the catalyst to oil ratio refers to the weight ratio of the catalytic cracking catalyst to the second reaction product.

The catalytic cracking catalyst provided by the invention is a catalyst capable of producing a reaction product containing low-carbon olefin by catalytic cracking of a heavy raw material and a light raw material. The catalytic cracking catalyst is commercially available or may be prepared according to methods well known to those skilled in the art. In particular, the catalytic cracking catalyst contains zeolite, inorganic oxide and optionally clay. The zeolite is contained in an amount of 1 to 50% by weight, the inorganic oxide is contained in an amount of 5 to 99% by weight, and the clay is contained in an amount of 0 to 70% by weight, based on the weight of the catalytic cracking catalyst. Preferably, in order to increase propylene yield and increase conversion, the zeolite comprises a shape-selective zeolite having an average pore size of less than 0.7 nm and a Y-type zeolite A stone; the shape selective zeolite having an average pore diameter of less than 0.7 nm is present in an amount of 25 to 90 wt% and the Y zeolite is present in an amount of 10 to 75 wt% on a dry basis and based on the total weight of the zeolite. Wherein the shape selective zeolite with average pore diameter less than 0.7 nanometer can be selected from at least one of ZSM series zeolite, ZRP zeolite, ferrierite, chabazite, cyclospar, erionite, A zeolite, column zeolite and turbid zeolite, and one or more than two of the above zeolite obtained by physical and/or chemical treatment. The ZSM series zeolite may be selected from one or more of ZSM-5, ZSM-8, ZSM-11, ZSM-12, ZSM-22, ZSM-23, ZSM-35, ZSM-38, ZSM-48 and other zeolite of similar structure. For a more detailed description of ZSM-5 see USP3702886 and for a more detailed description of ZRP see USP5232675, CN1211470A, CN1611299A. The Y-zeolite may be selected from at least one of rare earth Y-zeolite (REY), rare earth hydrogen Y-zeolite (REHY), ultrastable Y-zeolite (USY), and rare earth ultrastable Y-zeolite (REUSY). The inorganic oxide may be silica (SiO ₂ ) And/or aluminum oxide (Al) ₂ O ₃ ). The clay selected as the matrix, i.e., carrier, may be kaolin and/or halloysite.

The types of heavy and light feedstock are well known to those skilled in the art in accordance with the present invention.

The heavy raw material is heavy hydrocarbon and/or various animal and vegetable oil raw materials rich in hydrocarbon, and the heavy hydrocarbon can be one or more than one mixture selected from petroleum hydrocarbon, mineral oil and synthetic oil. The petroleum hydrocarbon may be vacuum wax oil, atmospheric residuum, vacuum residuum of a vacuum wax oil blending portion or other hydrocarbon oils obtained by secondary processing, such as one or more of coker wax oil, deasphalted oil, and furfural refined raffinate oil. The mineral oil may be one or more selected from coal liquefied oil, oil sand oil and shale oil. The synthetic oil can be distillate oil obtained by F-T synthesis of coal, natural gas or asphalt. The hydrocarbon-rich animal and vegetable oils can be various animal and vegetable oils. The heavy raw material is preferably at least one selected from the group consisting of vacuum wax oil, normal pressure wax oil, coking wax oil, deasphalted oil, furfural refined raffinate oil, coal liquefied oil, oil sand oil, shale oil, fischer-Tropsch synthetic oil and animal and vegetable oil.

The light feedstock is preferably an olefin-rich gasoline and/or C ₄ Hydrocarbon and/or diesel, said olefin-rich gasoline being selected from the gasoline fraction produced by the process and/or the gasoline fraction produced by other means. The gasoline fraction produced by other devices can be selected from one or more of catalytic pyrolysis crude gasoline, catalytic pyrolysis stable gasoline, coker gasoline, visbreaker gasoline and other gasoline fractions produced by oil refining or chemical processes, and preferably the gasoline fraction produced by the process. The olefin content of the olefin-rich gasoline may be 25 to 95 wt%, preferably 35 to 90 wt%, and more preferably 50 wt% or more. The final point of the olefin-rich gasoline is not more than 204 ℃, for example, the full range gasoline fraction having a distillation range of 35-204 ℃, or the narrow fraction thereof, for example, the gasoline fraction having a final point of not more than 85 ℃, preferably the gasoline fraction having a distillation range of 40-85 ℃. The C is ₄ The hydrocarbon is C ₄ The fraction is mainly composed of low molecular hydrocarbon in gas form at normal temperature and pressure, including C4 alkane, alkene and alkyne, and can be self-produced C-enriched ₄ The gaseous hydrocarbon product of the fraction, which may also be C-rich produced by other plant processes ₄ The fraction of gaseous hydrocarbons, preferably C, being self-produced by the process ₄ And (3) fraction. The C is ₄ The content of olefins in the hydrocarbon is more than 50 wt%, preferably more than 60 wt%, and most preferably more than 70 wt%. The diesel oil refers to the diesel oil fraction produced by the process and/or the diesel oil fraction produced by other devices. The gasoline fraction produced by other devices can be selected from one or more of catalytic pyrolysis diesel, straight-run diesel, hydrofined diesel, hydrocracking diesel, biodiesel, coker diesel, visbreaker diesel and other diesel fractions produced by oil refining or chemical processes, preferably the diesel fraction produced by the process. The oil slurry is oil slurry produced by the process. The end point of the diesel oil is not more than 3The temperature of 50℃may be, for example, a full range Chai Liufen having a distillation range of 205 to 350℃or a narrow fraction thereof. C in the light raw material ₄ The weight ratio of hydrocarbon to gasoline may be (0-2): 1, preferably (0-1.2): 1, more preferably (0-0.8): 1; the weight ratio of diesel to gasoline may be (0-2): 1, preferably (0-1.2): 1, more preferably (0-0.8): 1. Preferably, the weight ratio of the olefin-rich gasoline fed to the second downcomer reactor to the heavy feedstock fed to the first downcomer reactor is from (0.05 to 0.3): 1, more preferably from (0.1 to 0.2): 1. Preferably, the weight ratio of the diesel fraction fed to the second downpipe reactor to the heavy feedstock fed to the first downpipe reactor. (0.02-0.3): 1, more preferably (0.05-0.2): 1. Preferably, the weight ratio of slurry oil fed to the second downpipe reactor to heavy feedstock fed to the first downpipe reactor is from (0.01 to 0.2): 1, more preferably from (0.05 to 0.15): 1.

According to the invention, the catalytic cracking system comprises: a first downpipe reactor 2, a fluidized bed reactor 3, a regenerator 7 and a second downpipe reactor 9. The fluidized bed reactor 3 comprises a sedimentation section 4, a fluidized bed reaction section and a stripping section 5 from top to bottom. The first downpipe reactor 2 is in communication with a settling section 4 of the fluidized bed reactor 3. The second downpipe reactor 9 is in communication with the fluidized bed reaction section of the fluidized bed reactor 3. The regenerator 7 is in communication with the first downpipe reactor 2, the fluidized bed reactor 3 and the second downpipe reactor 9, respectively.

According to the invention, the first downpipe reactor 2 is provided with a catalyst inlet at the top, a heavy feed inlet at the upper part and a feed outlet at the bottom, as shown in fig. 1. In order to facilitate separation of the product and regeneration of the spent catalyst, the fluidized bed reactor 3 comprises a fluidized bed reaction section, a stripping section 5 arranged below the fluidized bed reaction section, and a settling section 4 arranged above the fluidized bed reaction section, wherein the fluidized bed reaction section, the stripping section 5 and the settling section 4 can be coaxially arranged and are in fluid communication. The fluidized bed reactor 3 is provided with a catalyst inlet, a first material inlet, a second material inlet, a catalyst outlet and a product outlet; the catalyst inlet and the second material inlet are located in the fluidized bed reaction section of the fluidized bed reactor 3, the first material inlet is located in the settling section 4 of the fluidized bed reactor 3, and the product outlet is located in the settling section 4 of the fluidized bed reactor 3, preferably at the top of the settling section 4. The catalyst outlet of the fluidized bed reactor 3 is located in the lower part of the stripping section 5. Preferably, steam and oil gas obtained by the reaction are stripped by the stripping section 5, are introduced into the bottom of the fluidized bed reactor, pass through the fluidized bed reactor and then are discharged out of the reactor, so that the partial pressure of the oil gas can be reduced, the residence time of the oil gas in the settling section is shortened, and the yield of the low-carbon olefin is increased. The second downer reactor 9 is provided with a catalyst inlet at the top, a light raw material inlet at the upper part and a material outlet at the bottom; preferably, the second downer reactor 9 is also provided with a slurry inlet located in the upper part. The material outlet of the first downpipe reactor 2 is communicated with the first material inlet of the sedimentation section 4 of the fluidized bed reactor 3. The material outlet of the second downer reactor 9 is communicated with the second material inlet of the fluidized bed reaction section of the fluidized bed reactor 3.

According to the present invention, the first downpipe reactor and the second downpipe reactor may each be independently selected from one or a combination of two of an equal diameter downpipe, an equal linear velocity downpipe and a variable diameter downpipe.

According to the present invention, the fluidized bed reactor may be selected from one of a fixed fluidized bed, a bulk fluidized bed, a bubbling bed, a turbulent bed, a fast bed, a transport bed and a dense bed reactor.

According to the invention, as shown in fig. 1, the regenerator 7 is provided with a catalyst inlet and a catalyst outlet; the catalyst inlet of the regenerator 7 is in communication with the stripping section 5 of the fluidized bed reactor 3. The catalyst outlet of the regenerator 7 is respectively communicated with the catalyst inlet of the fluidized bed reactor 3, the catalyst inlet of the first downpipe reactor 2 and the catalyst inlet of the second downpipe reactor 9. Preferably, the catalyst outlet of the regenerator 7 is respectively connected to the catalyst inlet of the fluidized bed reactor 3 via a second regeneration chute 11, to the catalyst inlet of the first downpipe reactor 2 via a third regeneration chute 11, and to the catalyst inlet of the second downpipe reactor 9 via a first regeneration chute 8.

According to the invention, the first reaction product and the spent catalyst leaving the first downpipe reactor 2 and the third reaction product and the spent catalyst leaving the fluidized bed reactor 3 enter a settling section 4, after which the spent catalyst carried therein is separated by settling, the first reaction product and the third reaction product can be subjected to subsequent product separation. And separating the first reaction product and the third reaction product to obtain dry gas, liquefied gas, gasoline, diesel oil and slurry oil. The product separation may be performed in a product separation device. The product separation device may be of the prior art, such as a fractionation column, and the invention is not particularly limited. According to the invention, the system further comprises a product separation device 12, as shown in fig. 1, said product separation device 12 being provided with a product inlet, a dry gas outlet, a liquefied gas outlet, a gasoline outlet, a diesel outlet and a slurry outlet. The inlet of the product separation device 12 communicates with the product outlet located in the settling section 4 of the fluidized bed reactor 3. In order to further increase the yield of light olefins, the liquefied gas outlet and/or the gasoline outlet and/or the diesel outlet of the product separation device 12 are in communication with the light feed inlet of the second downpipe reactor 9. The slurry outlet of the product separation device 12 is in communication with the light feed inlet of the second downpipe reactor 9, preferably the slurry outlet of the product separation device 12 is in communication with the slurry inlet of the second downpipe reactor 9.

The process and system provided by the present invention are further described below with reference to the accompanying drawings:

as shown in fig. 1, the high temperature regenerated catalyst is introduced into the second catalyst tank 10 at the top of the second downer reactor 9, the fluidized bed reactor 3 and the first catalyst tank 1 at the top of the first downer reactor 2 through the first regeneration inclined pipe 8, the second regeneration inclined pipe 11 and the third regeneration inclined pipe 13, respectively. Preheated or non-preheated olefin-rich gasoline fraction and/or C4 hydrocarbons and/or diesel is injected into the second downcomer reactor 9 via light feed line 20, and preheated slurry oil is introduced into the second downcomer reactor via return slurry oil line 18 with the second hydrocarbon feedstock via return slurry oil line 18The atomized water vapor of the atomized water vapor line 19 is mixed according to a certain proportion, injected into the second downlink tube reactor 9, mixed with the high-temperature catalyst from the second catalyst tank 10 and reacted, the reacted oil gas and the catalyst mixture are introduced into the fluidized bed reactor 3 for continuous reaction through an outlet distributor (not shown in the figure) of the second downlink tube reactor 9, and finally enter the sedimentation section 4 for separation of the oil gas and the catalyst; the separated oil gas (first reaction product/third reaction product) enters the subsequent product separation device 12 via oil gas line 21, and the separated spent catalyst preferably enters the regenerator 7 via spent inclined tube 6 after stripping in stripping section 5. The preheated heavy raw materials are mixed with atomized steam from a first atomized steam pipeline 15 according to a certain proportion through a heavy raw material pipeline 14, then injected into a first downlink pipe reactor 2 to be contacted and reacted with a high-temperature mixture (comprising fresh catalyst and regenerated catalyst) from a first catalyst tank 1, and reaction oil gas (first reaction product) and catalyst mixture enter a sedimentation section 4 through an outlet distributor (not shown) of the first downlink pipe reactor 2 to be separated from the catalyst; the separated oil and gas (first reaction product/third reaction product) enters the subsequent product separation device 12 through the oil and gas line 21. In the product separation device 12, the reaction product is separated into gaseous hydrocarbon (drawn off via a gaseous hydrocarbon line 23), gasoline (drawn off via a gasoline line 24), diesel (drawn off via a diesel line 25), light cycle oil (drawn off via a light cycle oil line 26), and slurry oil (drawn off via a separated slurry oil line 27). The cracked gaseous hydrocarbon withdrawn from gaseous hydrocarbon line 23 is separated and refined in subsequent stages to produce a polymerization grade propylene product and an olefin-rich C4 fraction, wherein the olefin-rich C4 fraction may be returned to the second downcomer reactor 9 for reconversion to ethylene and propylene. The gasoline led out by the gasoline pipeline 24 can be partially or completely returned to the reaction system for reconversion, or the gasoline can be firstly cut into light and heavy gasoline fraction segments, and the light gasoline is partially or completely returned to the reaction system for reconversion, preferably, the light gasoline is returned to the second downpipe reactor 9 for reconversion; the diesel oil led out from the diesel oil pipeline 25 can be partially or completely returned to the second downer reactor 9 for reconversion; the separated slurry oil from the slurry oil line 27 may be partially or completely returned to the second downer reactor 9 for reconversion. Separated by settling section 4 The obtained catalyst enters the fluidized bed reactor 3 and then enters the stripping section 5, stripping steam is injected through a stripping steam pipeline 16 and contacts with the carbon deposition catalyst in a countercurrent way, reaction oil gas carried by the carbon deposition catalyst is stripped out as much as possible, and then is introduced into the settling section 4 through the fluidized bed reactor 3 and is led out of the reactor together with other oil gas through an oil gas pipeline 21. The stripped catalyst is sent into a regenerator 7 through a spent agent inclined tube 6 to be burnt and regenerated. Oxygen-containing gas is injected into the regenerator 7 through an oxygen-containing gas line 29, and regeneration flue gas is led out through a regeneration flue gas line 22. The regenerated catalyst enters different reactors through a first regeneration inclined pipe 8, a second regeneration inclined pipe 11 and a third regeneration inclined pipe 13 for recycling. During the above embodiments, the lifting medium introduced to the second lifting medium line 28 and the first lifting medium line 17 to lift the regenerant into the first catalyst tank 1 and the second catalyst tank 10 may be selected from the group consisting of steam, C1-C4 hydrocarbons, N ₂ Or conventional catalytic cracking dry gas, preferably dry gas according to the invention.

The present invention will be described in detail by examples.

The feedstock oil and the catalytic cracking catalyst used in the following examples and comparative examples were the same. The raw material A used is a cracking raw material, and the specific properties are shown in Table 1. The catalytic cracking catalyst adopted is MMC-2 produced by China petrochemical Qilu catalyst factory, contains shape-selective zeolite with average pore diameter smaller than 0.7 nanometer and Y-type molecular sieve, and the specific properties are shown in Table 2.

Example 1

The embodiment is used for explaining the catalytic cracking process provided by the invention.

The test was performed in a medium catalytic cracker. The catalytic cracking process is carried out in a catalytic cracking system, and the system comprises a set of independent reaction regeneration systems: a first downpipe reactor, a second downpipe reactor, and a fluidized bed reactor. The fluidized bed reactor comprises a fluidized bed reaction section and a steam stripping section arranged below the fluidized bed reaction section. The inner diameter of the first downer reactor is 16 mm, the length of the first downer reactor is 3200 mm, and the outlet at the bottom of the first downer reactor is connected with the settling section at the upper part of the fluidized bed reactor. The catalyst is MMC-2 catalyst, the raw materials shown in Table 1 are cracked, the first reaction product obtained by the reaction and the catalyst are separated in a settling section of a fluidized bed reactor, the first reaction product enters a product separation device for separation, and the catalyst enters the fluidized bed reactor. The inner diameter of the second downer reactor is 12 mm, the length of the second downer reactor is 2200 mm, and the bottom of the second downer reactor is connected with the fluidized bed reactor in series. The catalyst is MMC-2 catalyst, light gasoline (distillation range is 30-85 ℃, the mass fraction of olefin is 52%, the mass ratio of olefin to heavy raw material is 0.15:1) and slurry oil (distillation range is 350-finishing point, the mass ratio of olefin to heavy raw material is 0.05:1) which are rich in olefin from a product separation device are used as light raw materials for cracking, the obtained mixture of oil gas (second reaction product) and catalyst enters a fluidized bed reactor for cracking reaction again, and the diameter (inner diameter) of the fluidized bed reactor is 64 mm, and the height is 600 mm; oil gas (third reaction product) obtained by the reaction of the fluidized bed reactor is separated from the catalyst in a settling section of the fluidized bed reactor, and the catalyst enters the fluidized bed reactor. All spent catalyst from the fluidized bed reactor enters a stripper at the lower part of the fluidized bed reactor for stripping and then enters a regenerator for regeneration, and the obtained regenerant enters the second downer reactor, the first downer reactor and the fluidized bed reactor again for reaction. And (3) enabling the oil gas (third reaction product) obtained after the reaction in the fluidized bed reactor to enter a product separation device for separation. The reaction operating conditions and the reaction results are shown in tables 3 and 4.

Comparative example 1

This comparative example is used to illustrate a reference catalytic cracking process.

The test was performed in a medium catalytic cracker. The catalytic cracking process is carried out in a catalytic cracking system, and the system comprises a set of independent reaction regeneration systems: a first downpipe reactor, a second downpipe reactor, and a fluidized bed reactor. The fluidized bed reactor comprises a fluidized bed reaction section and a steam stripping section arranged below the fluidized bed reaction section. The inner diameter of the first downpipe is 16 mm, the length is 3200 mm, the outlet of the bottom of the first downpipe reactor is connected with the fluidized bed reactor in series, the diameter (inner diameter) of the fluidized bed reactor is 64 mm, and the height of the fluidized bed reactor is 600 mm. The catalyst used was an MMC-2 catalyst and the feedstock shown in Table 1 was cracked. The reacted oil gas and the catalyst enter a fluidized bed reactor to carry out cracking reaction again. The second downer reactor has an inner diameter of 12 mm and a length of 2200 mm, adopts an MMC-2 catalyst as the catalyst, and is used for cracking light gasoline (the distillation range is 30-85 ℃, the mass fraction of olefin is 52 percent and the mass ratio of the olefin to heavy raw materials is 0.15:1) which is rich in olefin and comes from a product separation device as light raw materials, and the obtained oil gas and catalyst mixture enters a fluidized bed reactor for cracking reaction again. Separating the product obtained by the fluidized bed reaction from the catalyst in a settling section of the fluidized bed reactor (comprising the reaction product and the catalyst obtained by introducing the product obtained by the reaction of the first downer reactor into the fluidized bed reactor for reaction and the reaction product and the catalyst obtained by introducing the product obtained by the reaction of the second downer reactor into the fluidized bed reactor for reaction), stripping the separated catalyst in a stripping section at the lower part of the fluidized bed reactor, regenerating in a regenerator, and reacting the obtained regenerated agent in the first downer reactor, the second downer reactor and the fluidized bed reactor again. And (5) separating the obtained oil gas product and feeding the oil gas product into a product separation device. The reaction operating conditions and the reaction results are shown in tables 3 and 4.

Example 2

Referring to example 1, except that light olefin-rich gasoline (distillation range: 30 to 85 ℃, mass fraction of olefin: 52%, mass ratio to heavy feedstock: 0.15:1) and slurry oil (distillation range: 350 ℃ to end point, mass ratio to heavy feedstock: 0.05:1) from the product separation device were cracked as light feedstock, a diesel fraction obtained from the product separation device was returned to the second downpipe reactor (mass ratio of diesel to heavy feedstock: 0.1:1) was also included. The reaction operating conditions and the reaction results are shown in tables 3 and 4.

TABLE 1

TABLE 2

TABLE 3 Table 3

TABLE 4 Table 4

From the results in tables 3 and 4, it is understood that the first downpipe reactor of example 1 was introduced into the settling section above the fluidized bed reactor, the diesel yield was significantly increased, the diesel cetane number was significantly increased, and the diesel quality was improved, as compared with the first downpipe reactor of comparative example 1 in which the outlet was introduced into the bed reaction section of the fluidized bed reactor. Meanwhile, the ratio of the yield of the low-carbon olefin to the yield of the dry gas is obviously increased, and the distribution of the product is improved. In example 2, when a part of the diesel fraction was introduced into the light feed inlet of the second downer reactor, the yields of ethylene, propylene and butene were increased, but the diesel yield was lowered and the quality of diesel was also deteriorated, as compared with example 1. Recycling the slurry oil back to the second downer reactor in examples 1-2 reduced slurry oil yield, but increased the conversion of heavy oil.

The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, a number of simple variants of the technical solution of the invention are possible, including combinations of the individual technical features in any other suitable way, which simple variants and combinations should likewise be regarded as being disclosed by the invention, all falling within the scope of protection of the invention.

Claims

1. A catalytic cracking process, comprising:

(5) In a regenerator, regenerating a catalyst to be regenerated from a fluidized bed reactor to obtain a regenerated catalyst;

the process further comprises: separating the first reaction product from the third reaction product to obtain dry gas, liquefied gas, gasoline, diesel oil and slurry oil; at least part of separated gasoline is taken as the light raw material to be sent into the second downer reactor to be contacted with a catalytic cracking catalyst for catalytic cracking reaction; the weight ratio of the gasoline fed into the second downer reactor to the heavy raw material fed into the first downer reactor is (0.05-0.3): 1; at least part of the separated oil slurry is sent into the second downer reactor to be contacted with a catalytic cracking catalyst for catalytic cracking reaction; the weight ratio of the slurry oil fed into the second downer reactor to the heavy raw material fed into the first downer reactor is (0.01-0.2): 1;

the process further comprises the following steps: using the regenerated catalyst obtained in the step (5) as a catalytic cracking catalyst of the step (1), the step (3) and the step (4);

the same catalytic cracking catalyst is used in the first downpipe reactor, the fluidized bed reactor and the second downpipe reactor.

2. The process of claim 1, wherein the process further comprises: and (3) carrying out gas-solid separation on the third reaction product and the catalyst to be regenerated through a settling section at the upper part of the fluidized bed reactor, sending the third reaction product obtained by separation out of the fluidized bed reactor, and allowing the catalyst to be regenerated obtained by separation to enter the fluidized bed reactor.

3. The process according to claim 1 or 2, wherein the process further comprises: a step of stripping before regenerating the spent catalyst from the fluidized bed reactor.

4. A process according to claim 3, wherein the stripping is carried out in a stripper in the lower part of the fluidized bed reactor.

5. The process according to claim 1 or 2, wherein the process further comprises: and (3) taking the separated liquefied gas and/or diesel oil as the light raw material to be sent into the second downer reactor to be contacted with a catalytic cracking catalyst for catalytic cracking reaction.

6. The process of claim 1 wherein the weight ratio of gasoline fed to the second downpipe reactor to heavy feedstock fed to the first downpipe reactor is (0.10-0.2): 1.

7. A process according to claim 5, wherein the weight ratio of diesel fed to the second downpipe reactor to heavy feedstock fed to the first downpipe reactor is from (0.02 to 0.3): 1.

8. The process according to claim 7, wherein the weight ratio of diesel oil fed to the second downpipe reactor to heavy feedstock fed to the first downpipe reactor is (0.05-0.2): 1.

9. The process according to claim 1, wherein the weight ratio of slurry oil fed to the second downpipe reactor to heavy feedstock fed to the first downpipe reactor is from (0.05 to 0.15): 1.

10. The process of claim 1, wherein,

in the step (1), the conditions of the catalytic cracking reaction include: the temperature is 510-690 ℃; the ratio of the agent to the oil is 5-20; the reaction time is 0.5-8 seconds;

in the step (3), the conditions of the catalytic cracking reaction include: the temperature is 520-720 ℃; the agent-oil ratio is 8-26; the reaction time is 1-10 seconds;

in the step (4), the conditions of the catalytic cracking reaction include: the temperature is 480-650 ℃; weight hourly space velocity of 1-35 hours ^-1 The method comprises the steps of carrying out a first treatment on the surface of the The ratio of the agent to the oil is 6-20; the reaction pressure is 0.15-0.35MPa.

11. The process of claim 10, wherein in step (1), the conditions of the catalytic cracking reaction comprise: the temperature is 520-650 ℃; the agent-oil ratio is 7-18; the reaction time is 1.5-4 seconds.

12. The process of claim 10, wherein in step (3), the conditions of the catalytic cracking reaction comprise: the temperature is 530-700 ℃; the agent-oil ratio is 10-24; the reaction time is 2-7 seconds.

13. The process of claim 10, wherein in step (4), the conditions of the catalytic cracking reaction comprise: the temperature is 500-640 ℃; weight hourly space velocity of 2-33 hours ^-1 The method comprises the steps of carrying out a first treatment on the surface of the The agent-oil ratio is 7-18; the reaction pressure is 0.2-0.35MPa.

14. The process of claim 1 wherein 10 to 70 wt.% of the regenerated catalyst is fed to the first downer reactor of step (1), 20 to 60 wt.% of the regenerated catalyst is fed to the fluidized bed reactor of step (4), and 10 to 40 wt.% of the regenerated catalyst is fed to the second downer reactor of step (3), based on the total weight of regenerated catalyst exiting the regenerator per unit time.

15. The process of any one of claims 1, 10-13, wherein the catalytic cracking catalyst comprises zeolite, inorganic oxide, and optionally clay; the content of the zeolite is 1-50 wt%, the content of the inorganic oxide is 5-99 wt% and the content of the clay is 0-70 wt% based on the total weight of the catalytic cracking catalyst;

the zeolite comprises shape selective zeolite and Y-type zeolite with average pore diameter less than 0.7 nanometer; the shape selective zeolite having an average pore size of less than 0.7 nm is present in an amount of 25 to 90 wt.% and the Y-zeolite is present in an amount of 10 to 75 wt.% on a dry basis and based on the total weight of the zeolite; the shape selective zeolite with the average pore diameter smaller than 0.7 nanometer is selected from ZSM series zeolite, ZRP zeolite, ferrierite, chabazite, cyclospar, erionite, A zeolite, column zeolite and turbid zeolite, and one or more than two of the above zeolite obtained by physical and/or chemical treatment; the Y-type zeolite is at least one selected from rare earth Y-type zeolite, rare earth hydrogen Y-type zeolite and ultrastable Y-type zeolite;

The inorganic oxide is silicon dioxide and/or aluminum oxide.

16. The process of any one of claims 1, 10-13, wherein the catalytic cracking catalyst comprises zeolite, inorganic oxide, and optionally clay; the content of the zeolite is 1-50 wt%, the content of the inorganic oxide is 5-99 wt% and the content of the clay is 0-70 wt% based on the total weight of the catalytic cracking catalyst;

the zeolite comprises shape selective zeolite and Y-type zeolite with average pore diameter less than 0.7 nanometer; the shape selective zeolite having an average pore size of less than 0.7 nm is present in an amount of 25 to 90 wt.% and the Y-zeolite is present in an amount of 10 to 75 wt.% on a dry basis and based on the total weight of the zeolite; the shape selective zeolite with the average pore diameter smaller than 0.7 nanometer is selected from ZSM series zeolite, ZRP zeolite, ferrierite, chabazite, cyclospar, erionite, A zeolite, column zeolite and turbid zeolite, and one or more than two of the above zeolite obtained by physical and/or chemical treatment; the Y-type zeolite is selected from rare earth ultrastable Y-type zeolite;

the inorganic oxide is silicon dioxide and/or aluminum oxide.

17. The process of claim 1, wherein the heavy feedstock is selected from at least one of reduced pressure wax oil, atmospheric pressure wax oil, coker wax oil, deasphalted oil, furfural refined raffinate oil, coal liquefaction oil, oil sand oil, shale oil, fischer-tropsch synthetic oil, and animal and vegetable oils; the light raw material is gasoline and/or C rich in olefin ₄ Hydrocarbons and/or diesel.