A method, system for producing chemical feedstocks including ethylene based on an isokinetic fluidized bed reactor

Abstract

This invention relates to a method and system for producing chemical feedstocks including ethylene based on an isotropic fluidized bed reactor. The method includes: (1) contacting and reacting feedstock oil with a shape-selective molecular sieve catalyst in an isotropic fluidized bed reactor to obtain an oil-catalyst mixture; (2) separating the oil-catalyst mixture to obtain reaction oil gas and a catalyst to be generated; and (3) separating the reaction oil gas in an oil-gas separation system to obtain chemical feedstocks including ethylene, C4 olefins, etc. In this invention, light petroleum hydrocarbons such as diesel oil are contacted with a shape-selective molecular sieve catalyst in an isotropic fluidized bed reactor, and ethylene, propylene, etc. are produced by maintaining self-heating equilibrium through regenerated flue gas circulation. This disclosed method can process naphtha, wax oil, residue oil, and other heavy oils while processing light hydrocarbons such as diesel oil. It achieves high yields of ethylene and propylene and can reach self-heating equilibrium, not only solving the problem of excess diesel production capacity in refineries but also compensating for the shortage of chemical feedstocks.

Description

Technical Field

[0001] This invention relates to the technical field of hydrocarbon catalytic cracking, and specifically to a method and system for producing chemical feedstock including ethylene based on a constant linear velocity fluidized bed reactor. Background Technology

[0002] In recent years, the diesel-to-gasoline ratio in the refined oil market has been declining. Diesel consumption peaked at 176 Mt in 2014 and has since experienced zero or negative growth. Statistics show that the emissions per unit mileage of a heavy-duty diesel vehicle are approximately 150 times that of a light-duty gasoline vehicle of the same stage, and the annual emissions are approximately 750 times that of a light-duty gasoline vehicle of the same stage. This pollution situation further restricts the development of diesel vehicles. It is projected that by 2025, diesel consumption will decrease to 168 Mt, and the diesel-to-gasoline ratio will drop from the current 1.4 to less than 1. This will mean a surplus of hundreds of millions of tons of diesel products, and the high particulate matter emissions from diesel engines will further restrict diesel use, resulting in a surplus of millions of tons of diesel fuel for vehicles from refineries with a capacity of tens of millions of tons. Reducing the diesel-to-gasoline ratio of refinery products and finding alternative markets for diesel fuel have become urgent issues to address. Straight-run diesel accounts for about 50% of total diesel production. Reducing straight-run diesel production or converting it into other high-value-added products to adapt to future changes in diesel demand is of great significance for ensuring the supply and demand balance of my country's refined oil market.

[0003] For the conversion of straight-run diesel, light diesel oil of less than 10% can usually be blended into ethylene cracking feedstock. However, compared with other light feedstocks, straight-run diesel oil has a lower olefin yield and a shorter coking cycle after steam cracking. Alternatively, hydrocracking can process straight-run diesel oil with a hydrogen consumption of 2.5%, a naphtha yield of 50%–60%, and a liquefied petroleum gas (LPG) yield of 4%–5%. In recent years, some domestic refineries have also used conventional catalytic cracking units to blend straight-run diesel oil to reduce the diesel-to-gasoline ratio. For example, Sinopec Hainan Refining & Chemical Co., Ltd.'s conventional catalytic cracking unit blends straight-run diesel oil with the Changsanxian line, achieving a gasoline yield of 41%. However, the propylene volume fraction in the LPG decreases by 0.52 percentage points, and the isobutylene volume fraction decreases by 0.12 percentage points, which is not conducive to increasing the production of low-carbon olefins.

[0004] The progress of catalytic cracking of straight-run diesel alone or catalytic cracking technology has been slow. On the one hand, straight-run diesel has always been a high-value vehicle fuel with high cetane number, large consumption, and scarce resources. On the other hand, the yield of gasoline or chemical feedstocks such as ethylene and propylene produced by catalytic cracking of straight-run diesel is low. In addition, the coking rate of catalytic cracking of straight-run diesel is low, which is insufficient to maintain the self-heating balance of conventional fluidized bed catalytic cracking. Moreover, catalytic cracking requires a high temperature.

[0005] Existing research both domestically and internationally has mainly focused on improving conversion rates and compensating for heat imbalances. For example, China National Petroleum Corporation (CNPC) patent CN111607425A discloses a method for cracking straight-run diesel, which involves catalytically cracking straight-run diesel (after removing alkaline nitrogen with dihydrogen phosphate) and inert gases such as nitrogen in a fixed-bed or moving-bed reactor equipped with activated pretreated ZSM-5 nano-molecular sieves. Patent CN111718751A discloses a method for preparing ZSM-5 nano-molecular sieve catalysts modified with transition metals and / or non-metals in this method. As described in these two patents, straight-run diesel achieved a conversion rate of up to 80.16% and a low-carbon olefin yield of 34.13% using a fixed-bed reactor with external heating at a reaction temperature as high as 600℃; however, its single-pass cycle is as short as 47 hours, requiring frequent reactor switching. While a moving-bed reactor extends the single-pass cycle to 78 hours, it is more difficult to operate.

[0006] Both patents CN104418685B and CN104418686A from China Petroleum & Chemical Corporation (Sinopec) disclose a method for catalytic cracking of straight-run diesel in a riser reactor using methane as a diluent and a heat exchanger between the recycled agent and flue gas. Patent CN104418686A also discloses a technology for extracting aromatics from cracked gasoline and steam cracking of H2+C1-C4 alkane. As described in these two patents, the mature fluidized bed technology enables continuous reaction-regeneration, and the heat balance problem is solved by setting up a heat exchanger between the recycled agent and flue gas. At a reaction temperature as high as 630℃ and a recycled agent / oil mass ratio of 18, a diesel conversion rate of up to 83.83% and ethylene and propylene yields of 16.52% and 35.19%, respectively, were achieved through C4 refining. However, the heat exchange between the recycled agent and flue gas requires the addition of a heat exchanger, resulting in a complex process, high equipment investment, low heat exchange efficiency, and the presence of oxygen in the flue gas leading to incomplete combustion of the recycled agent and potential tail-burning hazards.

[0007] Therefore, given the current oversupply of diesel fuel, the urgent technical problem to be solved is how to address the difficulty of diesel cracking, enabling diesel fuel to be better converted into high-value products through catalytic cracking reactions, thereby increasing the yield of ethylene and propylene while reducing the yield of coke. Summary of the Invention

[0008] This invention provides a method and system for producing chemical feedstocks including ethylene based on a constant-velocity fluidized bed reactor. The purpose is to enable light oils such as diesel to be better converted into high-value products such as ethylene and propylene through catalytic cracking reactions in a constant-velocity fluidized bed reactor.

[0009] In a first aspect, the present invention relates to a method for producing a chemical feedstock including ethylene based on a constant linear velocity fluidized bed reactor, the method comprising the following steps:

[0010] (1) The feedstock oil and the shape-selective molecular sieve catalyst are reacted in a constant linear velocity fluidized bed reactor to obtain an oil-catalyst mixture;

[0011] The shape-selective molecular sieve catalyst includes a shape-selective molecular sieve, which is selected from a ten-membered ring structure molecular sieve; the catalyst in the constant linear velocity fluidized bed reactor flows upward, and the inner diameter of the reaction section decreases from top to bottom.

[0012] (2) Separate the oil mixture to obtain the reaction oil gas and the catalyst to be generated;

[0013] The oil-agent mixture is subjected to cyclone separation and sedimentation to obtain a first reactive oil-gas and a precursor catalyst for residual oil-gas; the precursor catalyst for residual oil-gas is stripped to obtain a second reactive oil-gas and the precursor catalyst; the reactive oil-gas includes the first reactive oil-gas and the second reactive oil-gas.

[0014] (3) The reaction oil and gas are separated in an oil and gas separation system to obtain a chemical feedstock including ethylene, C4 olefins, light gasoline fraction, heavy aromatics fraction and oil slurry.

[0015] (4) The catalyst to be generated is introduced into the regenerator and regenerated in an oxygen-containing atmosphere to obtain a regenerated catalyst and flue gas; at least a portion of the regenerated catalyst is returned to the constant linear velocity fluidized bed reactor for recycling, and at least a portion of the flue gas is returned to the regenerator for recycling.

[0016] Optionally, in step (1):

[0017] The ten-membered ring molecular sieve is selected from one or more combinations of ZSM-5, ZSM-11, ZSM-12, ZSM-23, ZSM-35, ZSM-38, ZSM-48, and ZRP-5 molecular sieves, and the average pore size of the ten-membered ring molecular sieve is 0.5-0.6 nm; and / or,

[0018] The shape-selective molecular sieve catalyst further includes oxides and optional clays, wherein the oxides are selected from one or more combinations of alumina, silica, and modified oxides; and the modified oxides are selected from one or more metal oxides and / or non-metal oxides from Group IA, Group IIA, Group VA, Group IIIB, and Group VIII.

[0019] The ten-membered ring structure molecular sieve is a molecular sieve modified by the modified oxide.

[0020] The ten-membered ring molecular sieve accounts for 40-70% of the mass of the shape-selective molecular sieve catalyst, and the modified oxide accounts for 1.0-10.0% of the mass of the shape-selective molecular sieve catalyst.

[0021] And / or,

[0022] The average particle size of the shape-selective molecular sieve catalysts is 40–150 micrometers.

[0023] Optionally, the feedstock is diesel oil, which is fed into the constant linear velocity fluidized bed reactor from the bottom of the reaction section;

[0024] Preferably, at least a portion of the C4 olefins, the light gasoline fraction, the heavy aromatics fraction, and one or more of the slurry are fed through the reaction section into the constant linear velocity fluidized bed reactor for reprocessing;

[0025] The feed points for the C4 olefins, the light gasoline fraction, and the heavy aromatics fraction are located below or via the diesel feed point; the feed point for the slurry is located above the diesel feed point.

[0026] Optionally, the feedstock includes diesel oil and heavy oil, wherein the diesel oil is fed into the constant velocity fluidized bed reactor from the lower part of the reaction section, and the heavy oil is fed into the constant velocity fluidized bed reactor from the middle part of the reaction section;

[0027] Preferably, at least a portion of the C4 olefins, the light gasoline fraction, the heavy aromatics fraction, and one or more of the slurry are fed through the reaction section into the constant linear velocity fluidized bed reactor for reprocessing;

[0028] The feed points for the C4 olefins, the light gasoline fraction, and the heavy aromatics fraction are located below or via the diesel feed point; the slurry is fed via the heavy oil feed point.

[0029] Optionally, the feedstock is diesel oil, which is fed into the constant linear velocity fluidized bed reactor from the bottom of the reaction section;

[0030] Furthermore, step (1) also includes:

[0031] The heavy oil is brought into contact with the shape-selective molecular sieve catalyst in a riser reactor for reaction.

[0032] In step (2), a portion of the oil-catalyst mixture originates from the contact reaction between the diesel oil and the shape-selective molecular sieve catalyst, and another portion originates from the contact reaction between the heavy oil and the shape-selective molecular sieve catalyst; in step (4), a portion of the regenerated catalyst is returned to the constant linear velocity fluidized bed reactor for recycling, and another portion of the regenerated catalyst is returned to the riser reactor for recycling.

[0033] Preferably, at least a portion of one or more of the C4 olefins, the light gasoline fraction, the heavy aromatics fraction, and the slurry are fed into the riser reactor for reprocessing;

[0034] The feed points for the C4 olefins, the light gasoline fraction, and the heavy aromatics fraction are located below the feed point for the heavy oil, and the oil slurry is fed through the feed point for the heavy oil.

[0035] Optionally, the diesel fuel is selected from one or more combinations of straight-run diesel fuel, catalytic cracking diesel fuel, and hydrotreated diesel fuel; and / or,

[0036] The diesel fuel has a boiling point of 180–380°C and a density of less than or equal to 850 kg / m³. 3 .

[0037] Optionally, the heavy oil is wax oil and / or residue oil.

[0038] Optionally, the conditions for the reaction between the diesel fuel and the shape-selective molecular sieve catalyst in step (1) include:

[0039] The reaction temperature is 620-720℃, the reaction pressure is 0.2-0.5MPa, the reaction time is 3.0-7.0 seconds, and the weight ratio of the shape-selective molecular sieve catalyst to the diesel oil is (6-10):1.

[0040] The diesel fuel is fed into the constant linear velocity fluidized bed reactor under fluidized medium conditions.

[0041] The fluidizing medium is atomized water, and the mass ratio of the atomized water to the diesel fuel is (0.20-0.30):1;

[0042] The linear velocity of oil and gas in the reaction section is 1.0-2.0 m / s;

[0043] And / or,

[0044] The method also includes the following steps prior to step (1):

[0045] The raw material oil is preheated to a preheating temperature, which is 200-400°C, preferably 260-360°C.

[0046] The preheating is achieved by heating in a furnace or by exchanging heat between the raw oil and the chemical material obtained from step (3).

[0047] Optionally, the conditions under which the heavy oil and the shape-selective molecular sieve catalyst react in the riser reactor include:

[0048] The reaction temperature is 620–720℃, the reaction pressure is 0.2–0.5 MPa, the weight ratio of the shape-selective molecular sieve catalyst to the heavy oil is (6–10):1, and the reaction time is 3.0–7.0 seconds.

[0049] The heavy oil is fed into the riser reactor under fluidized medium conditions;

[0050] The fluidizing medium is atomized water, and the mass ratio of the atomized water to the heavy oil is (0.20-0.30):1;

[0051] The linear velocity of oil and gas in the riser reactor is 2.0-12.0 m / s.

[0052] Optionally, in step (3), the oil-gas separation system is selected from one or more of the following combined: a fractionation column with a theoretical plate number of more than 20, an absorption stabilization system, and a gas separation system;

[0053] The separation described in step (3) also yields propylene, H2 and C1-C4 alkanes, BTX fraction and methylnaphthalene oil fraction.

[0054] Optionally, in step (4):

[0055] The regeneration temperature of the regenerator is 640-780℃, and the pressure is 0.3-0.6MPa;

[0056] The recycling rate of the regenerated catalyst is 150-200 kg / (m²). 2 ·Second);

[0057] The regeneration atmosphere in the regenerator is selected from air, oxygen-enriched air, and pure oxygen.

[0058] The flue gas is optionally subjected to heat exchange before being returned to the regenerator for recycling, and the temperature of the flue gas returned to the regenerator for recycling is 340-580°C.

[0059] In a second aspect, the present invention relates to a system for producing chemical feedstock including ethylene based on a constant velocity fluidized bed reactor, the system comprising a constant velocity fluidized bed reactor, a cyclone separator, a settling tank, an oil-gas separation system, and a regenerator;

[0060] The constant velocity fluidized bed reactor is provided with a reactor pre-lifting section, a reactor reaction section, a reactor outlet section, and a catalyst stripping section; the catalyst in the constant velocity fluidized bed reactor flows upward; the cyclone separator and the settler are located above the catalyst stripping section; the inner diameter of the reactor outlet section is smaller than that of the reactor reaction section;

[0061] The outlet of the pre-lift section of the reactor is connected to the inlet of the reaction section of the reactor, and the outlet of the reaction section of the reactor is connected to the inlet of the outlet section of the reactor.

[0062] The reactor reaction section is a variable diameter reaction section, and the inner diameter of the reactor reaction section gradually decreases from top to bottom; the lower part of the reactor reaction section is provided with a light hydrocarbon feedstock oil inlet and a first atomizing steam inlet, and the light hydrocarbon feedstock oil inlet and the first atomizing steam inlet are connected.

[0063] The oil outlet of the reactor outlet section is connected to the oil inlet of the cyclone separator, the catalyst outlet of the cyclone separator is connected to the inlet of the settler, and the oil-gas outlet of the cyclone separator is connected to the oil-gas inlet of the oil-gas separation system.

[0064] The outlet of the settling tank is connected to the inlet of the catalyst stripping section, the catalyst outlet of the catalyst stripping section is connected to the inlet of the regenerated catalyst, and the oil and gas outlet of the catalyst stripping section is connected to the oil and gas separation system.

[0065] The regenerator is provided with an oxygen-containing regenerated gas inlet and a flue gas outlet. The flue gas outlet and the oxygen-containing regenerated gas inlet are connected through a flue gas circulation system. The regenerated catalyst outlet of the regenerator is connected to the catalyst inlet of the pre-lift section of the reactor through a first regenerator delivery pipeline. The bottom of the pre-lift section of the reactor is provided with a first fluidizing medium inlet.

[0066] The oil-gas separation system is equipped with an ethylene outlet, a propylene outlet, an H2 and C1-C4 alkane outlet, a C4 olefin outlet, a light gasoline fraction outlet, a BTX fraction outlet, a heavy aromatics fraction outlet, a methylnaphthalene oil fraction outlet, and an oil slurry outlet.

[0067] Preferably, the oil and gas outlet of the cyclone separator is connected to the oil and gas inlet of the oil and gas separation system through a reaction oil and gas pipeline, and the oil and gas outlet of the catalyst stripping section is connected to the oil and gas inlet of the oil and gas separation system through the reaction oil and gas pipeline.

[0068] Preferably, a stripping medium inlet is provided at the lower part of the catalyst stripping section;

[0069] Preferably, the catalyst outlet of the catalyst stripping section is connected to the regenerated catalyst inlet of the regenerator via a regenerated catalyst delivery pipeline;

[0070] Preferably, a first heavy feedstock oil inlet and a second atomizing steam inlet are provided in the middle of the reactor reaction section, and the first heavy feedstock oil inlet and the second atomizing steam inlet are connected.

[0071] Preferably, the reactor reaction section is provided with a first remelting inlet and a second remelting inlet, the first remelting inlet and the second remelting inlet being located below and above the light hydrocarbon feedstock inlet, respectively;

[0072] The C4 olefin outlet, the light gasoline fraction outlet, and the heavy aromatics fraction outlet are respectively connected to the first recycle inlet, or respectively connected to the light hydrocarbon feedstock inlet; the slurry outlet is connected to the second recycle inlet, or connected to the first heavy feedstock inlet.

[0073] Optionally, the system is further provided with a riser reactor, which is provided with a second heavy feedstock oil inlet and a third atomizing steam inlet, the second heavy feedstock oil inlet and the third atomizing steam inlet being connected in communication;

[0074] The regenerated catalyst outlet of the regenerator is connected to the catalyst inlet at the bottom of the riser reactor through a second regenerated agent delivery pipeline. A second fluidizing medium inlet is also provided at the bottom of the riser reactor.

[0075] The oil outlet of the riser reactor is connected to the oil inlet of the cyclone separator;

[0076] Preferably, the riser reactor is provided with a third refining port, which is located below the inlet of the second heavy feedstock oil. The C4 olefin outlet, the light gasoline fraction outlet, and the heavy aromatics fraction outlet are respectively connected to the third refining port, and the slurry outlet is connected to the inlet of the second heavy feedstock oil.

[0077] Beneficial effects:

[0078] This invention enables feedstock oil and shape-selective molecular sieve catalyst to react in a constant linear velocity fluidized bed reactor. By controlling the inner diameter of the reaction section to decrease sequentially from top to bottom, the catalyst to flow upwards, and controlling the feedstock oil inlet position, light feedstock oils such as diesel can be better converted into low-carbon olefins, significantly improving the yield of ethylene and propylene. Furthermore, self-heating balance can be achieved by returning the regenerated flue gas to the regenerator for recycling. Attached Figure Description

[0079] Figure 1This is a schematic diagram of a specific embodiment of a system for producing chemical feedstock including ethylene based on a constant linear velocity fluidized bed reactor according to the present invention;

[0080] Figure 2 This is a schematic diagram of another specific embodiment of the system for producing chemical feedstock including ethylene based on a constant linear velocity fluidized bed reactor according to the present invention.

[0081] Explanation of reference numerals in the attached figures

[0082] I. Reactor pre-lifting section; II. Reactor reaction section; III. Reactor outlet section

[0083] IV. Settler; IV-1. Cyclone Separator; IV-2. Catalyst Stripping Section

[0084] 1. Constant velocity fluidized bed reactor; 2. Light hydrocarbon feedstock inlet; 3. First atomizing steam inlet.

[0085] 4 First fluidized medium inlet; 5 Reaction oil and gas pipeline; 6 Oil and gas separation system

[0086] 7. Ethylene export; 8. Propylene export; 9. H2 and C1-C4 alkane export.

[0087] 10C4 olefins outlet, 11 light gasoline fraction outlet, 12BTX fraction outlet

[0088] 13 Heavy Aromatics Fraction Outlet 14 Methylnaphthalene Oil Fraction Outlet 15 Oil Slurry Outlet

[0089] 16 First Heavy Feedstock Inlet 17 Second Atomizing Steam Inlet 18 Stripping Medium Inlet

[0090] 19 Regenerator delivery pipeline; 20 Regenerator; 21 Oxygen-containing regeneration gas inlet.

[0091] 22 First regenerant delivery pipeline 23 Flue gas outlet 24 Flue gas recirculation system

[0092] 25 Riser reactor; 26 Second fluidizing medium inlet; 27 Second regenerant delivery line

[0093] 28 Second heavy feedstock oil inlet 29 Third atomizing steam inlet Detailed Implementation

[0094] The present application will now be described in further detail with reference to the accompanying drawings and embodiments. Through these descriptions, the features and advantages of the present application will become clearer and more apparent.

[0095] The term “exemplary” as used herein means “serving as an example, embodiment, or illustration.” Any embodiment illustrated herein as “exemplary” is not necessarily to be construed as superior to or better than other embodiments. Although various aspects of embodiments are shown in the accompanying drawings, the drawings are not necessarily drawn to scale unless specifically indicated otherwise.

[0096] Furthermore, the technical features involved in the different embodiments of this application described below can be combined with each other as long as they do not conflict with each other.

[0097] In a first aspect, the present invention relates to a method for producing a chemical feedstock including ethylene based on a constant linear velocity fluidized bed reactor, the method comprising the following steps:

[0098] (1) The feedstock oil and the shape-selective molecular sieve catalyst are reacted in a constant linear velocity fluidized bed reactor to obtain an oil-catalyst mixture;

[0099] The shape-selective molecular sieve catalyst includes a shape-selective molecular sieve, which is selected from a ten-membered ring structure molecular sieve; the catalyst in the constant linear velocity fluidized bed reactor flows upward, and the inner diameter of the reaction section decreases from top to bottom.

[0100] (2) Separate the oil mixture to obtain the reaction oil gas and the catalyst to be generated;

[0101] The oil-agent mixture is subjected to cyclone separation and sedimentation to obtain a first reactive oil-gas and a precursor catalyst for residual oil-gas; the precursor catalyst for residual oil-gas is stripped to obtain a second reactive oil-gas and the precursor catalyst; the reactive oil-gas includes the first reactive oil-gas and the second reactive oil-gas.

[0102] (3) The reaction oil and gas are separated in an oil and gas separation system to obtain a chemical feedstock including ethylene, C4 olefins, light gasoline fraction, heavy aromatics fraction and oil slurry.

[0103] (4) The catalyst to be generated is introduced into the regenerator and regenerated in an oxygen-containing atmosphere to obtain a regenerated catalyst and flue gas; at least a portion of the regenerated catalyst is returned to the constant linear velocity fluidized bed reactor for recycling, and at least a portion of the flue gas is returned to the regenerator for recycling.

[0104] It should be noted that the catalyst in the constant velocity fluidized bed reactor can also flow downwards, preferably upwards; in step (2), stripping can remove flammable gases such as oil and gas entrained in the catalyst. In the method of the present invention, the feedstock oil and the shape-selective molecular sieve catalyst are contacted and reacted in the constant velocity fluidized bed reactor. The catalyst flows upwards in the constant velocity fluidized bed reactor, and the inner diameter of the reaction section of the constant velocity fluidized bed reactor decreases from top to bottom. This flow pattern and inner diameter setting enable the feedstock oil to be better catalytically cracked into high-value products such as ethylene and propylene in the constant velocity fluidized bed reactor.

[0105] Furthermore, by maintaining self-heating balance through regenerated flue gas recirculation, it can better produce chemical feedstocks such as ethylene, resulting in high yields of high-value products such as ethylene and propylene. The method of this invention can process light oils such as diesel while also processing heavy oils such as naphtha, wax oil, and residual oil, not only solving the problem of diesel overcapacity in refineries but also compensating for the shortage of chemical feedstocks.

[0106] According to a specific embodiment of the method described in the first aspect of the present invention, in step (1):

[0107] The ten-membered ring molecular sieve is selected from one or more combinations of ZSM-5, ZSM-11, ZSM-12, ZSM-23, ZSM-35, ZSM-38, ZSM-48, and ZRP-5 molecular sieves, and the average pore size of the ten-membered ring molecular sieve is 0.5-0.6 nm; and / or,

[0108] The shape-selective molecular sieve catalyst further includes oxides and optional clays, wherein the oxides are selected from one or more combinations of alumina, silica, and modified oxides; and the modified oxides are selected from one or more metal oxides and / or non-metal oxides from Group IA, Group IIA, Group VA, Group IIIB, and Group VIII.

[0109] The ten-membered ring structure molecular sieve is a molecular sieve modified by the modified oxide.

[0110] The ten-membered ring molecular sieve accounts for 40-70% of the mass of the shape-selective molecular sieve catalyst, and the modified oxide accounts for 1.0-10.0% of the mass of the shape-selective molecular sieve catalyst.

[0111] And / or,

[0112] The average particle size of the shape-selective molecular sieve catalysts is 40–150 micrometers.

[0113] It should be noted that the shape-selective molecular sieve has been modified by the modified oxide; the oxide other than the modified oxide may include heat-resistant alumina, silica, or other binders and / or optional natural porous support materials such as clay. Preferably, the shape-selective molecular sieve catalyst is a composite material composed of metal and / or non-metal modified ZSM-5 series mesoporous molecular sieves with MFI structure, alumina, silica, or other binders, and optional natural porous support materials such as clay.

[0114] It should be noted that when producing ethylene and other chemical feedstocks in a variable-diameter constant-velocity fluidized bed reactor based on the method of the present invention, using a catalyst containing a shape-selective molecular sieve with a ten-membered ring structure, such as an MFI molecular sieve containing a ten-membered ring structure, can further and better catalyze the reaction of feedstock oil into high-value products such as ethylene and propylene, and improve the yield of products such as low-carbon olefins.

[0115] According to a first specific embodiment of the method of the first aspect of the present invention, the feedstock oil is diesel oil, and the diesel oil is fed into the constant linear velocity fluidized bed reactor from the lower part of the reaction section;

[0116] Preferably, at least a portion of the C4 olefins, the light gasoline fraction, the heavy aromatics fraction, and one or more of the slurry are fed through the reaction section into the constant linear velocity fluidized bed reactor for reprocessing;

[0117] The feed points for the C4 olefins, the light gasoline fraction, and the heavy aromatics fraction are located below or via the diesel feed point; the feed point for the slurry is located above the diesel feed point.

[0118] It should be noted that, compared to fixed-bed and moving-bed reactors, constant-velocity fluidized-bed reactors can operate continuously without external heating; compared to conventional riser reactors, the oil-catalyst contact is more complete, making them more suitable for the catalytic cracking of light hydrocarbons such as diesel oil, which expands in volume. During years of research and development, the inventors of this application have innovatively discovered that feeding diesel oil into the lower part of the reaction section facilitates its better conversion into ethylene, propylene, etc. Furthermore, by feeding C4 olefins, light gasoline fractions, and heavy aromatic fractions back into the reactor at the aforementioned locations, the yields of ethylene, propylene, etc., can be further increased. By feeding the oil slurry back into the reactor at these locations, heat can be better utilized and the reactor's thermal balance can be maintained, allowing the reaction to proceed more effectively.

[0119] According to a second specific embodiment of the method of the first aspect of the present invention, the feedstock oil includes diesel oil and heavy oil, wherein the diesel oil is fed into the constant velocity fluidized bed reactor from the lower part of the reaction section, and the heavy oil is fed into the constant velocity fluidized bed reactor from the middle part of the reaction section;

[0120] Preferably, at least a portion of the C4 olefins, the light gasoline fraction, the heavy aromatics fraction, and one or more of the slurry are fed through the reaction section into the constant linear velocity fluidized bed reactor for reprocessing;

[0121] The feed points for the C4 olefins, the light gasoline fraction, and the heavy aromatics fraction are located below or via the diesel feed point; the slurry is fed via the heavy oil feed point.

[0122] It should be noted that in this embodiment, diesel and heavy oil undergo catalytic cracking in the same reactor. During long-term research and development, the inventors of this application have innovatively discovered that feeding diesel and heavy oil separately at the aforementioned positions can increase the proportion of high-value products such as ethylene and propylene in the final chemical feedstock, thus increasing the yield of these high-value products. By feeding C4 olefins, light gasoline fractions, and heavy aromatics fractions back into the reactor at the aforementioned positions, the yield of high-value products such as ethylene and propylene can be further increased. Furthermore, by feeding the oil slurry back into the reactor at the aforementioned positions, heat can be better utilized, the reactor can maintain better thermal balance, and the reaction can proceed more effectively.

[0123] According to a third specific embodiment of the method of the first aspect of the present invention, the feedstock oil is diesel oil, and the diesel oil is fed into the constant linear velocity fluidized bed reactor from the lower part of the reaction section;

[0124] Furthermore, step (1) also includes:

[0125] The heavy oil is brought into contact with the shape-selective molecular sieve catalyst in a riser reactor for reaction.

[0126] In step (2), a portion of the oil-catalyst mixture originates from the contact reaction between the diesel oil and the shape-selective molecular sieve catalyst, and another portion originates from the contact reaction between the heavy oil and the shape-selective molecular sieve catalyst; in step (4), a portion of the regenerated catalyst is returned to the constant linear velocity fluidized bed reactor for recycling, and another portion of the regenerated catalyst is returned to the riser reactor for recycling.

[0127] Preferably, at least a portion of one or more of the C4 olefins, the light gasoline fraction, the heavy aromatics fraction, and the slurry are fed into the riser reactor for reprocessing;

[0128] The feed points for the C4 olefins, the light gasoline fraction, and the heavy aromatics fraction are located below the feed point for the heavy oil, and the oil slurry is fed through the feed point for the heavy oil.

[0129] It should be noted that in this embodiment, diesel and heavy oil undergo catalytic cracking in different reactors. This embodiment is a catalytic cracking process that couples a constant-velocity fluidized bed reactor and a riser reactor. The oil-fuel mixture after the diesel reaction and the oil-fuel mixture after the heavy oil reaction can be separated separately or together. In this embodiment, during reprocessing, C4 olefins, light gasoline fractions, heavy aromatic fractions, and slurry are fed back into the reactors at the positions described above. This allows for better reactions in both reactors, increasing the yield of ethylene and propylene and obtaining more high-value products.

[0130] According to a specific embodiment of the method described in the first aspect of the present invention, the diesel fuel is selected from one or more combinations of straight-run diesel fuel, catalytic cracking diesel fuel, and hydrotreated diesel fuel; and / or,

[0131] The diesel fuel has a boiling point of 180–380°C and a density of less than or equal to 850 kg / m³. 3 .

[0132] It should be noted that the method of the present invention has a wide range of applicability, and can be applied to various other light hydrocarbon feedstocks in addition to the diesel oil mentioned above.

[0133] According to a specific embodiment of the method described in the first aspect of the present invention, the heavy oil is wax oil and / or residue oil.

[0134] It should be noted that the method of the present invention has a wide range of applicability and can be applied to various other heavy oils besides the heavy oils mentioned above.

[0135] According to a specific embodiment of the method described in the first aspect of the present invention, the conditions for the contact reaction between the diesel fuel and the shape-selective molecular sieve catalyst in step (1) include:

[0136] The reaction temperature is 620-720℃, the reaction pressure is 0.2-0.5MPa, the reaction time is 3.0-7.0 seconds, and the weight ratio of the shape-selective molecular sieve catalyst to the diesel oil is (6-10):1.

[0137] The diesel fuel is fed into the constant linear velocity fluidized bed reactor under fluidized medium conditions.

[0138] The fluidizing medium is atomized water, and the mass ratio of the atomized water to the diesel fuel is (0.20-0.30):1;

[0139] The linear velocity of oil and gas in the reaction section is 1.0-2.0 m / s;

[0140] And / or,

[0141] The method also includes the following steps prior to step (1):

[0142] The raw material oil is preheated to a preheating temperature, which is 200-400°C, preferably 260-360°C.

[0143] The preheating is achieved by heating in a furnace or by exchanging heat between the raw oil and the chemical material obtained from step (3).

[0144] It should be noted that the method of the present invention, in a variable-diameter constant-velocity fluidized bed reactor, involves diesel fuel undergoing a high-temperature, high-catalyst-to-oil-ratio catalytic cracking reaction in contact with a highly active catalyst. This converts diesel fuel into gasoline and liquefied petroleum gas (LPG), achieving a high conversion rate at a relatively high reaction temperature and enabling efficient continuous production. Furthermore, by controlling the reaction conditions as described above, the yields of ethylene, propylene, and other products can be further increased in the method of the present invention.

[0145] According to a specific embodiment of the method described in the first aspect of the present invention, the conditions for the contact reaction of the heavy oil and the shape-selective molecular sieve catalyst in the riser reactor include:

[0146] The reaction temperature is 620–720℃, the reaction pressure is 0.2–0.5 MPa, the weight ratio of the shape-selective molecular sieve catalyst to the heavy oil is (6–10):1, and the reaction time is 3.0–7.0 seconds.

[0147] The heavy oil is fed into the riser reactor under fluidized medium conditions;

[0148] The fluidizing medium is atomized water, and the mass ratio of the atomized water to the heavy oil is (0.20-0.30):1;

[0149] The linear velocity of oil and gas in the riser reactor is 2.0-12.0 m / s.

[0150] It should be noted that, in this embodiment, by controlling the reaction conditions of heavy oil as described above, the reaction in the riser reactor can proceed better, thereby converting more heavy oil into high-value products such as ethylene and propylene.

[0151] According to a specific embodiment of the method described in the first aspect of the present invention, in step (3), the oil-gas separation system is selected from one or more of the following combined: a fractionating column with a theoretical plate number of more than 20, an absorption stabilization system, and a gas separation system;

[0152] The separation described in step (3) also yields propylene, H2 and C1-C4 alkanes, BTX fraction and methylnaphthalene oil fraction.

[0153] It should be noted that the oil-gas separation system is a high-precision separation system. Through precise separation by this system, ethylene, propylene, H2, C1-C4 alkanes, C4 olefins, light gasoline fraction, BTX fraction, heavy aromatics fraction, methylnaphthalene oil fraction, and oil slurry can be obtained. The BTX fraction refers to a mixture of benzene, toluene, and xylene, commonly known as light aromatics.

[0154] Specifically, the oil and gas are precisely separated by a high-precision separation system. The gaseous products are separated into ethylene, propylene, C4 olefins, H2, and C1-C4 alkanes. The liquid products are separated into light gasoline fractions with an initial boiling point of -60℃, BTX fractions with a boiling point of 60-150℃, heavy aromatics fractions with a boiling point of 150-240℃, methylnaphthalene oil fractions with a boiling point of 240-340℃, and slurry oil with a boiling point >340℃. The BTX fraction is hydrogenated and then extracted to obtain BTX and light aromatics raffinate. This system better meets the demand for producing more chemical feedstocks from the catalytic cracking of light hydrocarbons, unlike conventional catalytic cracking separation systems that separate liquid products into gasoline fractions (initial boiling point -200℃), diesel fractions (200-360℃), and slurry oil fractions (>360℃). Preferably, the C4 olefins, light gasoline fractions, light aromatics raffinate, heavy aromatics fractions, and slurry oil obtained from the high-precision separation can be returned to the reactor for reprocessing. Ethylene and BTX can be produced better by refining light gasoline fractions, light aromatics raffinate, and heavy aromatics fractions. Refining oil slurry can further supplement the heat required by the reactor.

[0155] According to a specific embodiment of the method described in the first aspect of the present invention, in step (4):

[0156] The regeneration temperature of the regenerator is 640-780℃, and the pressure is 0.3-0.6MPa;

[0157] The recycling rate of the regenerated catalyst is 150-200 kg / (m²). 2 ·Second);

[0158] The regeneration atmosphere in the regenerator is selected from air, oxygen-enriched air, and pure oxygen.

[0159] The flue gas is optionally subjected to heat exchange before being returned to the regenerator for recycling, and the temperature of the flue gas returned to the regenerator for recycling is 340-580°C.

[0160] It should be noted that in the method of this invention, the regeneration atmosphere is preferably an oxygen-rich and / or pure oxygen atmosphere. Compared with conventional air regeneration, the regeneration gas requires less heat to heat up, has higher charring intensity, and a higher regeneration temperature, which can maintain a higher regenerant temperature. The regenerated high-temperature flue gas can be partially or completely recycled back to the regenerator. The oxygen-containing high-temperature flue gas, without heat exchange or after partial heat exchange, can be partially or completely returned to the regenerator for recycling under the above conditions. This can make full use of the oxygen in the flue gas, maintain a higher regeneration temperature and a higher regenerant temperature in the regenerator, solve the problem of the flue gas carrying heat out of the regeneration system, and reduce emissions of carbon dioxide and other waste gases, resulting in significant energy saving and emission reduction.

[0161] Secondly, the present invention relates to a system for producing chemical feedstocks including ethylene based on a constant-velocity fluidized bed reactor, such as... Figure 1 As shown, the system includes a constant linear velocity fluidized bed reactor 1, a cyclone separator IV-1, a settling tank IV, an oil-gas separation system 6, and a regenerator 20;

[0162] The constant velocity fluidized bed reactor 1 is provided with a reactor pre-lifting section I, a reactor reaction section II, a reactor outlet section III, and a catalyst stripping section IV-2; the catalyst in the constant velocity fluidized bed reactor 1 flows upward; the cyclone separator IV-1 and the settler IV are located above the catalyst stripping section IV-2; the inner diameter of the reactor outlet section III is smaller than that of the reactor reaction section II;

[0163] The outlet of the pre-lift section I of the reactor is connected to the inlet of the reaction section II of the reactor, and the outlet of the reaction section II of the reactor is connected to the inlet of the outlet section III of the reactor.

[0164] The reactor reaction section II is a variable diameter reaction section, and the inner diameter of the reactor reaction section II gradually decreases from top to bottom; the lower part of the reactor reaction section II is provided with a light hydrocarbon feedstock oil inlet 2 and a first atomizing steam inlet 3, and the light hydrocarbon feedstock oil inlet 2 and the first atomizing steam inlet 3 are connected.

[0165] The oil outlet of reactor outlet section III is connected to the oil inlet of cyclone separator IV-1, the catalyst outlet of cyclone separator IV-1 is connected to the inlet of settler IV, and the oil and gas outlet of cyclone separator IV-1 is connected to the oil and gas inlet of oil and gas separation system 6.

[0166] The outlet of the settling tank IV is connected to the inlet of the catalyst stripping section IV-2, the catalyst outlet of the catalyst stripping section IV-2 is connected to the inlet of the regenerator 20, and the oil and gas outlet of the catalyst stripping section IV-2 is connected to the oil and gas separation system 6.

[0167] The regenerator 20 is provided with an oxygen-containing regenerated gas inlet 21 and a flue gas outlet 23. The flue gas outlet 23 and the oxygen-containing regenerated gas inlet 21 are connected through a flue gas circulation system 24. The regenerated catalyst outlet of the regenerator 20 is connected to the catalyst inlet of the pre-lifting section I of the reactor through a first regenerator delivery pipeline 22. The bottom of the pre-lifting section I of the reactor is provided with a first fluidizing medium inlet 4.

[0168] The oil-gas separation system 6 is equipped with an ethylene outlet 7, a propylene outlet 8, an H2 and C1-C4 alkane outlet 9, a C4 olefin outlet 10, a light gasoline fraction outlet 11, a BTX fraction outlet 12, a heavy aromatics fraction outlet 13, a methylnaphthalene oil fraction outlet 14, and an oil slurry outlet 15.

[0169] Preferably, the oil and gas outlet of the cyclone separator IV-1 is connected to the oil and gas inlet of the oil and gas separation system 6 through the reaction oil and gas pipeline 5, and the oil and gas outlet of the catalyst stripping section IV-2 is connected to the oil and gas inlet of the oil and gas separation system 6 through the reaction oil and gas pipeline 5.

[0170] Preferably, a stripping medium inlet 18 is provided at the lower part of the catalyst stripping section IV-2;

[0171] Preferably, the catalyst outlet of the catalyst stripping section IV-2 is connected to the inlet of the regenerated catalyst of the regenerator 20 through the regenerated catalyst delivery pipeline 19;

[0172] Preferably, the middle part of the reactor reaction section II is provided with a first heavy feedstock oil inlet 16 and a second atomizing steam inlet 17, and the first heavy feedstock oil inlet 16 and the second atomizing steam inlet 17 are connected.

[0173] Preferably, the reactor reaction section II is provided with a first remelting inlet and a second remelting inlet, the first remelting inlet and the second remelting inlet being located below and above the light hydrocarbon feedstock inlet 2, respectively;

[0174] The C4 olefin outlet 10, the light gasoline fraction outlet 11, and the heavy aromatics fraction outlet 13 are respectively connected to the first recycle inlet or to the light hydrocarbon feedstock inlet 2; the slurry outlet 15 is connected to the second recycle inlet or to the first heavy feedstock inlet 16.

[0175] It should be noted that in the system of the present invention, the constant linear velocity fluidized bed reactor 1 and the regenerator 20 can be arranged in parallel or overlapping, and the constant linear velocity fluidized bed reactor 1 and the settling tank IV can be built-in or external; the catalyst is lifted by media such as air and / or water vapor, so that it circulates between the reactor and the regenerator.

[0176] The constant linear velocity fluidized bed reactor described in this invention refers to a fluidized bed reactor in which the oil and gas in catalytic cracking reaction maintain a relatively uniform linear velocity. Compared with a conventional fluidized bed with a uniform diameter, the oil and gas in the constant linear velocity fluidized bed reactor contact the catalyst in a plug flow state with a uniform linear velocity. The catalyst density is high, and the oil and gas contact is more complete.

[0177] It should be noted that light hydrocarbon feedstocks such as diesel can be fed into the lower part of reactor reaction section II through light hydrocarbon feedstock inlet 2 and atomized by atomized steam entering through the first atomized steam inlet 3. The reacted oil-fuel mixture flows into cyclone separator IV-1 through reactor outlet section III for cyclone separation to obtain first reacted oil gas and residual oil gas as a catalyst to be generated. The first reacted oil gas flows into oil-gas separation system 6 through reacted oil gas pipeline 5 for separation. The residual oil gas as a catalyst to be generated flows into settling tank IV for settling. The settled residual oil gas as a catalyst to be generated enters catalyst stripping section IV-2 for stripping to obtain second reacted oil gas and the catalyst to be generated. The obtained second reacted oil gas enters oil-gas separation system 6 through reacted oil gas pipeline 5 for separation. The obtained catalyst to be generated enters regenerator 20 through catalyst delivery pipeline 19 for regeneration. The obtained regenerated catalyst enters reactor pre-lift section I through first regenerator delivery pipeline 22. The regenerated flue gas can be partially or completely returned to regenerator 20 for recycling after heat exchange or without heat exchange.

[0178] Heavy oil can enter the middle of the reactor reaction section II through the first heavy feed oil inlet 16 and the atomized steam entering through the second atomized steam inlet 17, where it comes into contact with the catalyst to react. The oil-catalyst mixture after the reaction enters the cyclone separator IV-1 for cyclone separation, and then undergoes catalyst sedimentation, stripping, regeneration of the catalyst to be produced, and oil-gas separation in sequence.

[0179] The system of the present invention is based on a constant linear velocity fluidized bed reactor for diesel fuel, or for the catalytic reaction of diesel fuel and heavy oil. In particular, by setting the feed inlets for diesel fuel, heavy oil and recycled oil as described above, the diesel fuel and heavy oil can react better, which can significantly improve the yield of high-value products such as ethylene and propylene.

[0180] According to a specific embodiment of the system described in the second aspect of the present invention, such as Figure 2 As shown, the system is also provided with a riser reactor 25, which is provided with a second heavy feedstock oil inlet 28 and a third atomizing steam inlet 29, and the second heavy feedstock oil inlet 28 and the third atomizing steam inlet 29 are connected.

[0181] The regenerated catalyst outlet of the regenerator 20 is connected to the catalyst inlet at the bottom of the riser reactor 25 through a second regenerator delivery pipeline 27. A second fluidizing medium inlet 26 is also provided at the bottom of the riser reactor 25.

[0182] The oil outlet of the riser reactor 25 is connected to the oil inlet of the cyclone separator IV-1;

[0183] Preferably, the riser reactor 25 is provided with a third refining port, which is located below the second heavy feedstock inlet 28. The C4 olefin outlet 10, the light gasoline fraction outlet 11, and the heavy aromatics fraction outlet 13 are respectively connected to the third refining port, and the slurry outlet 15 is connected to the second heavy feedstock inlet 28.

[0184] It should be noted that in this embodiment, light hydrocarbon feedstocks such as diesel oil are reacted in a constant-velocity fluidized bed reactor 1, while heavy oil is reacted in a riser reactor 25. Heavy oil enters the riser reactor 25 through a second heavy feedstock inlet 28, and the regenerated catalyst enters the bottom of the riser reactor 25 through a second regenerator delivery line 27. The heavy oil contacts the catalyst to undergo a catalytic reaction, and the resulting oil-catalyst mixture enters a cyclone separator IV-1 for oil-catalyst separation, followed by sedimentation, stripping, and oil-gas separation. By having the two feedstocks undergo catalytic reactions in the two reactors described above, and especially by controlling the feedstock and recycled oil positions as described above, the reaction can proceed more effectively, resulting in the production of higher-value products such as ethylene and propylene.

[0185] It should be noted that the system described in the second aspect of the present invention can be used to produce chemical feedstocks including ethylene by catalytic cracking of feedstock oil based on the method described in the first aspect of the present invention, and the method of the first aspect of the present invention can be implemented based on the system described in the second aspect.

[0186] One specific implementation of this disclosure is as follows: Figure 1 As shown, in this embodiment, an upward-flowing, variable-diameter, constant-velocity fluidized bed reactor 1 is used. Light hydrocarbon feedstock oil enters the reactor via the bottom feed inlet 2 to contact the regenerator for catalytic cracking. The regenerator is then separated from the oil and gas and regenerated, while a portion of the regenerated flue gas is recycled back to the regenerator. The process flow is as follows:

[0187] Light hydrocarbon feedstock enters the bottom or lower part of reactor reaction section II in constant velocity fluidized bed reactor 1 through light hydrocarbon feedstock inlet 2 and atomization by atomized steam flowing in through the first atomized steam inlet 3. Meanwhile, hot regenerator is introduced into reactor pre-lift section I of constant velocity fluidized bed reactor through the first regenerator delivery pipeline 22. Under the fluidization of fluidizing medium entering through the first fluidizing medium inlet 4, it rises into reactor reaction section II. Light hydrocarbon feedstock comes into contact with hot regenerator to undergo catalytic cracking reaction.

[0188] After the reaction, the oil-gas mixture with the catalyst enters the cyclone separator IV-1 through reactor outlet section III for oil-catalyst separation. The separated catalyst is settled in settling tank IV to catalyst stripping section IV-2. After stripping, the stripping medium enters through stripping medium inlet 18 and enters regenerator 20 through regenerator delivery pipeline 19.

[0189] The catalyst is regenerated in an oxygen-containing atmosphere inside the regenerator. The oxygen-containing regeneration gas entering through the oxygen-containing regeneration gas inlet 21 includes air, oxygen, etc., and the regeneration temperature is 640-780℃. The regenerated catalyst is recycled. The regenerated flue gas flows out through the flue gas outlet 23 and can be partially recycled back to the regenerator through the flue gas circulation system 24.

[0190] The separated reaction oil and gas enter the oil and gas separation system 6 through the reaction oil and gas pipeline 5, and are separated into ethylene flowing out of ethylene outlet 7, propylene flowing out of propylene outlet 8, H2 and C1-C4 alkanes flowing out of H2 and C1-C4 alkanes flowing out of H2 and C1-C4 alkanes flowing out of H2 and C4 olefins flowing out of ...

[0191] C4 olefins, light gasoline fractions, heavy aromatics fractions, and slurry oil can be recycled or not, depending on production needs. To maximize the production of chemical feedstocks, recycling of C4 olefins, light gasoline, and heavy aromatics fractions is preferred. This recycled material can be mixed with light feedstock oil and then fed into the constant-velocity fluidized bed reactor 1 via the light hydrocarbon feedstock oil inlet 2. More preferably, it should enter the bottom of reactor reaction section II, i.e., below the light hydrocarbon feedstock oil nozzle. To meet the unit's self-heating balance requirements, slurry oil recycling is preferred. The slurry oil and / or heavy feedstock oil are atomized by atomizing steam and then fed into the reactor, preferably into the middle of reactor reaction section II, i.e., above the light hydrocarbon feedstock oil nozzle.

[0192] Figure 2This is a schematic diagram of the process flow for another embodiment of this disclosure. Similar to the embodiment described above, the light hydrocarbon feedstock uses a variable-diameter, constant-velocity fluidized bed reactor 1. The difference is that the oil slurry is recycled and / or the heavy feedstock enters a conventional riser reactor 25. The two reactors can each use a separate settling tank or share a single settling tank; in this embodiment, both use a single settling tank. The process flow is as follows:

[0193] The light hydrocarbon feedstock oil fed into the reactor at inlet 2 is atomized by the atomized steam entering through the first atomized steam inlet 3 and enters the bottom of reactor reaction section II in the constant velocity fluidized bed reactor 1. Meanwhile, the hot regenerator is introduced into the reactor pre-lift section I of the constant velocity fluidized bed reactor through the first regenerator delivery line 22, and rises into reactor reaction section II under the fluidization of the fluidizing medium entering through the first fluidizing medium inlet 4. The light hydrocarbon feedstock oil then contacts the hot regenerator to undergo a catalytic cracking reaction.

[0194] The heavy feedstock oil enters the lower part of the riser reactor 25 after being atomized by the atomizing steam entering through the second heavy feedstock oil inlet 28 and the third atomizing steam inlet 29. Meanwhile, the hot regenerator is introduced into the bottom of the riser reactor through the second regenerator delivery pipeline 27 and rises under the fluidization of the fluidizing medium entering through the second fluidizing medium inlet 26. The heavy feedstock oil contacts the hot regenerator to carry out a catalytic cracking reaction.

[0195] The oil-catalyst mixture after the reaction of light hydrocarbon feedstock and heavy feedstock enters the cyclone separator IV-1 for oil-catalyst separation; the oil-catalyst mixture formed by the reaction oil and gas and the catalyst enters the cyclone separator IV-1 through the reactor outlet section III for oil-catalyst separation; the separated catalyst settles through the settler IV to the catalyst stripping section IV-2, and after being stripped by the stripping medium entering through the stripping medium inlet 18, it enters the regenerator 20 through the regenerator transport pipeline 19.

[0196] The catalyst is regenerated in an oxygen-containing atmosphere inside the regenerator. The oxygen-containing regeneration gas entering through the oxygen-containing regeneration gas inlet 21 includes air, oxygen, etc., and the regeneration temperature is 640-780℃. The regenerated catalyst is recycled. Part of the regenerated flue gas is circulated back to the regenerator through the flue gas circulation system 24.

[0197] The separated reaction oil and gas enter the oil and gas separation system 6 through the reaction oil and gas pipeline 5, and are separated into ethylene flowing out of ethylene outlet 7, propylene flowing out of propylene outlet 8, H2 and C1-C4 alkanes flowing out of H2 and C1-C4 alkanes flowing out of H2 and C1-C4 alkanes flowing out of H2 and C4 olefins flowing out of ...

[0198] C4 olefins, light gasoline fractions, heavy aromatics fractions, and slurry oil can be recycled or not, depending on production needs. For slurry oil recycling, priority is given to using heavy feedstock via the second heavy feedstock inlet 28 and the third atomizing steam inlet 29, which is then atomized before entering the riser reactor 25. To maximize chemical feedstock production, C4 olefins, light gasoline, and heavy aromatics fractions are preferentially recycled. These recycled fractions can be fed into the bottom of the riser reactor 25, specifically below the second heavy feedstock inlet 28, for catalytic cracking.

[0199] The present invention will be further described in detail below through embodiments, but these embodiments are not intended to limit the invention. All raw materials used in the embodiments are commercially available.

[0200] The light hydrocarbon feedstock used in the examples is hydrotreated diesel A, which is obtained by hydrorefining straight-run diesel from a certain refinery, and the heavy feedstock oil is cracked tail oil B, which is obtained by hydrocracking wax oil from a certain refinery. The properties of the two are shown in Table 1.

[0201] Table 1

[0202]

[0203]

[0204] The catalysts used in the examples are the same, and their preparation methods are briefly described below:

[0205] 1) Use 150kg of decationized water to slurry 22.6kg of hydrous kaolin (an industrial product of Suzhou Porcelain Clay Company, solid content 71.6m%), then add 16.4kg of pseudoboehmite (an industrial product of Shandong Aluminum Plant, solid content 63m%), adjust the pH to 2-4 with hydrochloric acid, stir evenly, let it stand and age at 60-70℃ for 1 hour, keeping the pH at 2-4, then lower the temperature to below 60℃, add 12.5Kg of aluminum sol (a product of Sinopec Catalyst Qilu Branch, Al2O3 content 21.7m%), stir for 40 minutes to obtain a mixed slurry.

[0206] 2) Add the ZRP-5 molecular sieve with MFI structure (an industrial product of Sinopec Catalyst Qilu Branch, SiO2 / Al2O3 = 39, phosphorus content P2O5 = 4.6 wt%, iron content Fe2O3 = 0.5 wt%, dry basis 35.8 kg) to the mixed slurry obtained in step 2), stir evenly, place in a bonding machine, add an appropriate amount of water, stir evenly, place in the air for 4 hours, and spray dry to form.

[0207] 3) The catalyst obtained by spray drying in step 2) is dried in a drying oven at 120°C for 3 hours, and then washed with ammonium dihydrogen phosphate solution (phosphorus content 1 m%) to remove free Na.+ Washing removes free Na + The catalyst, CAT-4, is obtained by drying it again.

[0208] The catalyst consists of 55.1 wt% phosphorus / iron modified shape-selective molecular sieve ZRP-5, 15.9 wt% pseudoboehmite, 4.2 wt% alumina sol, and 24.8% kaolin. Its properties are listed in Table 2.

[0209] Table 2

[0210]

[0211]

[0212] Example 1

[0213] This embodiment follows Figure 1 The process was tested using hydrotreated straight-run diesel A (as listed in Table 1) as feedstock in a constant-velocity fluidized bed reactor with CAT-4 catalyst. Hydrotreated straight-run diesel A, preheated to 360℃, entered the bottom of the reaction section of the constant-velocity fluidized bed reactor. At a reaction pressure of 0.35 MPa, water vapor was used as the fluidizing medium, with a vapor-to-feedstock mass ratio of 0.30. As the fluidizing medium flowed upwards, catalytic cracking was carried out at a reaction temperature (at the reactor outlet, the same below) of 680℃, a catalyst-to-feedstock weight ratio of 9.0, and a reaction time of 5.0 seconds. After the reaction, oil-catalyst separation was performed. The separated reaction gas was further separated by an oil-gas separation system to obtain products H2, ethylene, and... Propylene, C1-C4 alkanes, BTX, methylnaphthalene oil and C4 olefins, light gasoline fraction, heavy aromatics fraction and slurry oil; C4 olefins, light gasoline fraction, heavy aromatics fraction and slurry oil are recycled; the catalyst after oil-catalyst separation is stripped with steam to remove internally adsorbed oil and gas and then sent to a regenerator, where oxygen is used as the regeneration gas, and regeneration is carried out in contact with the catalyst at a regeneration temperature of 680-730℃; the regenerated catalyst is recycled, 40% of the regenerated flue gas is recycled, the circulating flue gas temperature is 500℃, and the regeneration dense phase temperature is maintained at 730℃. Operating conditions and product distribution are listed in Table 3.

[0214] As can be seen from Table 3, in Example 1, the hydrotreated straight-run diesel fuel underwent catalytic cracking in a constant-speed fluidized bed reactor, with an ethylene yield of 17.26 wt%, a propylene yield of 18.40 wt%, a light aromatic hydrocarbon (BTX: benzene + toluene + xylene) yield of 14.51 wt%, and a coke yield of 12.70 wt%.

[0215] Comparative Example 1

[0216] The catalytic cracking reaction was carried out using the same feedstock, catalyst, and process conditions as in Example 1, with the following differences: 1) Comparative Example 1 used a riser reactor; 2) Air was used as the regeneration gas, and the flue gas was not recirculated; 3) To maintain the same process conditions as in Example 1, combustion oil was injected into the regenerator to provide heat. The operating conditions and product distribution are listed in Table 3.

[0217] As can be seen from Table 3, compared with Comparative Example 1 (Riser Reactor), Example 1 (Isolinear Velocity Fluidized Bed Reactor) increased the ethylene yield by 1.40 percentage points, the propylene yield by 1.61 percentage points, and the light aromatic hydrocarbon (BTX: benzene + toluene + xylene) yield by 1.15 percentage points, while the coke yield decreased by 1.81 percentage points.

[0218] Example 2

[0219] This embodiment follows Figure 2 The process was tested using 70% hydrotreated straight-run diesel A and 30% cracked tail oil B as feedstocks, as shown in Table 1. The tests were conducted in a constant-velocity fluidized bed reactor and a riser reactor, respectively, using CAT-4 catalyst. Hydrotreated straight-run diesel A, preheated to 260℃, entered the bottom of the reaction section of the constant-velocity fluidized bed reactor, while cracked tail oil B, preheated to 260℃, entered the bottom of the conventional riser reactor. Both were tested at a reaction pressure of 0.30 MPa, with steam as the fluidizing medium and a steam-to-feedstock mass ratio of 0.20. As the fluidizing medium flowed upwards in the different reactors, catalytic cracking was carried out at a reaction temperature (at the reactor outlet) of 640℃, a catalyst-to-feedstock weight ratio of 7.5, and a reaction time of 6.5 seconds. The oil and gas from the cracked tail oil B reaction in the riser reactor, along with the catalyst, flowed into the constant-velocity fluidized bed reactor, where they were separated from the oil from the hydrotreated straight-run diesel A reaction. The reaction oil and gas after oil-gas separation are further separated by an oil-gas separation system to obtain products H2, ethylene, propylene, C1-C4 alkanes, BTX, methylnaphthalene oil and C4 olefins, light gasoline fraction, heavy aromatics fraction, and slurry oil. The C4 olefins, light gasoline fraction, heavy aromatics fraction, and slurry oil are then recycled. The catalyst awaiting regeneration after oil-gas separation is stripped with steam to remove internally adsorbed oil and gas before being sent to a regenerator. Oxygen-enriched air (20% oxygen and 80% air) is used as the regeneration gas, and regeneration is performed at a regeneration temperature of 680–710°C. The regenerated catalyst is recycled, and part of the regenerated flue gas is circulated at a temperature of 400°C, maintaining the regeneration dense phase temperature at 710°C. Operating conditions and product distribution are listed in Table 3.

[0220] As can be seen from Table 3, in Example 2, the hydrotreated straight-run diesel oil underwent catalytic cracking in a constant-velocity fluidized bed reactor while the cracked tail oil underwent catalytic cracking in a riser reactor. The yields were 16.45 wt% ethylene, 19.83 wt% propylene, 16.61 wt% light aromatics (BTX: benzene + toluene + xylene), and 7.49 wt% coke.

[0221] Comparative Example 2

[0222] The catalytic cracking reaction was carried out using the same feedstock, catalyst, and process conditions as in Example 2, with the following differences: 1) Both hydrotreated straight-run diesel A and cracked tail oil B in Comparative Example 2 used riser reactors; 2) Air was used as the regeneration gas, and the flue gas was not recirculated; 3) To maintain the same process conditions as in Example 2, combustion oil was injected into the regenerator to provide heat. The operating conditions and product distribution are listed in Table 3.

[0223] As can be seen from Table 3, compared with Comparative Example 2 (riser reactor), Example 2 (constant linear velocity fluidized bed reactor + riser reactor) increased the ethylene yield by 1.72 percentage points, the propylene yield by 0.85 percentage points, and the light aromatic hydrocarbon (BTX: benzene + toluene + xylene) yield by 0.36 percentage points, while the coke yield decreased by 1.69 percentage points.

[0224] Table 3

[0225]

[0226]

[0227] Through years of research, the inventors of this application have discovered that: (1) Diesel catalytic cracking differs from heavy oil catalytic cracking, as small molecules are difficult to crack, thus requiring a higher reaction severity; (2) The constant-velocity fluidized bed reactor adapts to the volume expansion reaction system and reduces the yield of dry gas and coke under high reaction severity of diesel; (3) Diesel catalytic cracking produces low levels of coke, and conventional heavy oil regeneration technology cannot maintain the heat required for its own reaction through self-heating balance; (4) The traditional catalytic cracking oil-gas separation system, which cuts oil products according to gasoline fraction (initial boiling point -200℃), diesel fraction (200-360℃), and slurry fraction (>360℃), cannot meet the demand for high-yield chemical feedstocks from light hydrocarbon catalytic cracking. This application solves the problem of heat balance in light hydrocarbon catalytic cracking by using a constant-velocity fluidized bed reactor with oxygen-enriched and / or pure oxygen regeneration, and by returning part and / or all of the high-temperature flue gas after regeneration to the regenerator. It also achieves a higher conversion rate of light hydrocarbon catalytic cracking at higher reaction temperatures, enabling better conversion of feedstocks such as diesel into high-value products such as ethylene and propylene.

[0228] In the description of this application, it should be noted that the terms "upper", "lower", "inner", "outer", "front", "rear", "left", "right", etc., indicate the orientation or positional relationship based on the orientation or positional relationship in the working state of this application. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0229] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0230] The present application has been described above with reference to preferred embodiments; however, these embodiments are merely exemplary and illustrative. Various substitutions and modifications can be made to the present application based on these embodiments, all of which fall within the protection scope of the present application.

Claims

1. A method for producing chemical feedstock including ethylene based on a constant-velocity fluidized bed reactor, characterized in that, The method includes the following steps: (1) The feedstock oil and the shape-selective molecular sieve catalyst are contacted and reacted in a constant linear velocity fluidized bed reactor to obtain an oil-catalyst mixture, wherein the feedstock oil is diesel oil, or the feedstock oil includes diesel oil and heavy oil; The shape-selective molecular sieve catalyst includes a shape-selective molecular sieve, which is selected from a ten-membered ring structure molecular sieve; the catalyst in the constant linear velocity fluidized bed reactor flows upward, and the inner diameter of the reaction section decreases from top to bottom. (2) Separate the oil mixture to obtain the reaction oil gas and the catalyst to be generated; The oil-agent mixture is subjected to cyclone separation and sedimentation to obtain a first reactive oil-gas and a precursor catalyst for residual oil-gas; the precursor catalyst for residual oil-gas is stripped to obtain a second reactive oil-gas and the precursor catalyst; the reactive oil-gas includes the first reactive oil-gas and the second reactive oil-gas. (3) The reaction oil and gas are separated in an oil and gas separation system to obtain a chemical feedstock including ethylene, C4 olefins, light gasoline fraction, heavy aromatic fraction and oil slurry; (4) The catalyst to be recycled is introduced into a regenerator for regeneration in an oxygen-containing atmosphere to obtain a regenerated catalyst and flue gas; at least a portion of the regenerated catalyst is returned to the constant-velocity fluidized bed reactor for recycling, and at least a portion of the flue gas is returned to the regenerator for recycling. The conditions for the reaction between the diesel fuel and the shape-selective molecular sieve catalyst in step (1) include: The reaction temperature is 620~720℃, the reaction pressure is 0.2~0.5MPa, the reaction time is 3.0-7.0 seconds, and the weight ratio of the shape-selective molecular sieve catalyst to the diesel oil is (6-10):

1. The diesel fuel is fed into the constant linear velocity fluidized bed reactor under fluidized medium conditions. The fluidizing medium is atomized water, and the mass ratio of the atomized water to the diesel fuel is (0.20-0.30):1; The linear velocity of oil and gas in the reaction section is 1.0-2.0 m / s. The feedstock oil is diesel oil, which is fed into the constant velocity fluidized bed reactor from the bottom of the reaction section. Furthermore, step (1) also includes: The heavy oil is brought into contact with the shape-selective molecular sieve catalyst in a riser reactor for reaction. In step (2), a portion of the oil-catalyst mixture originates from the contact reaction between the diesel oil and the shape-selective molecular sieve catalyst, and another portion originates from the contact reaction between the heavy oil and the shape-selective molecular sieve catalyst; in step (4), a portion of the regenerated catalyst is returned to the constant-velocity fluidized bed reactor for recycling, and another portion of the regenerated catalyst is returned to the riser reactor for recycling. The conditions under which the heavy oil and the shape-selective molecular sieve catalyst react in the riser reactor include: The reaction temperature is 620~720℃, the reaction pressure is 0.2~0.5MPa, the weight ratio of the shape-selective molecular sieve catalyst to the heavy oil is (6-10):1, and the reaction time is 3.0-7.0 seconds; The heavy oil is fed into the riser reactor under fluidized medium conditions; The fluidizing medium is atomized water, and the mass ratio of the atomized water to the heavy oil is (0.20-0.30):1; The linear velocity of oil and gas in the riser reactor is 2.0-12.0 m / s. The diesel fuel is reacted in the constant velocity fluidized bed reactor, and the heavy oil is reacted in the riser reactor. The constant velocity fluidized bed reactor (1) is provided with a reactor pre-lifting section (I), a reactor reaction section (II), a reactor outlet section (III), and a catalyst stripping section (IV-2); the catalyst in the constant velocity fluidized bed reactor (1) flows upward; the cyclone separator (IV-1) and the settler (IV) are located above the catalyst stripping section (IV-2); The oil outlet of the riser reactor (25) is connected to the oil inlet of the cyclone separator (IV-1).

2. The method according to claim 1, characterized in that, In step (1): The ten-membered ring molecular sieve is selected from one or more combinations of ZSM-5, ZSM-11, ZSM-12, ZSM-23, ZSM-35, ZSM-38, ZSM-48, and ZRP-5 molecular sieves, and the average pore size of the ten-membered ring molecular sieve is 0.5-0.6 nm; and / or, The shape-selective molecular sieve catalyst further includes oxides and optional clays, wherein the oxides are selected from one or more combinations of alumina, silica, and modified oxides; and the modified oxides are selected from one or more metal oxides and / or non-metal oxides from Group IA, Group IIA, Group VA, Group IIIB, and Group VIII. The ten-membered ring structure molecular sieve is a molecular sieve modified by the modified oxide. The ten-membered ring molecular sieve accounts for 40-70% of the mass of the shape-selective molecular sieve catalyst, and the modified oxide accounts for 1.0-10.0% of the mass of the shape-selective molecular sieve catalyst. And / or, The average particle size of the shape-selective molecular sieve catalysts is 40-150 micrometers.

3. The method according to claim 1, characterized in that, The feedstock is diesel oil, which is fed into the constant velocity fluidized bed reactor from the bottom of the reaction section.

4. The method according to claim 3, characterized in that, At least a portion of the C4 olefins, the light gasoline fraction, the heavy aromatics fraction, and one or more of the slurry are fed through the reaction section into the constant linear velocity fluidized bed reactor for reprocessing. The feed points for the C4 olefins, the light gasoline fraction, and the heavy aromatics fraction are located below or via the diesel feed point; the feed point for the slurry is located above the diesel feed point.

5. The method according to claim 1, characterized in that, The feedstock includes diesel oil and heavy oil. The diesel oil is fed into the constant velocity fluidized bed reactor from the bottom of the reaction section, and the heavy oil is fed into the constant velocity fluidized bed reactor from the middle of the reaction section.

6. The method according to claim 5, characterized in that, At least a portion of the C4 olefins, the light gasoline fraction, the heavy aromatics fraction, and one or more of the slurry are fed through the reaction section into the constant linear velocity fluidized bed reactor for reprocessing. The feed points for the C4 olefins, the light gasoline fraction, and the heavy aromatics fraction are located below or via the diesel feed point; the slurry is fed via the heavy oil feed point.

7. The method according to claim 1, characterized in that, At least a portion of the C4 olefins, the light gasoline fraction, the heavy aromatics fraction, and one or more of the slurry are fed into the riser reactor for reprocessing; The feed points for the C4 olefins, the light gasoline fraction, and the heavy aromatics fraction are located below the feed point for the heavy oil, and the oil slurry is fed through the feed point for the heavy oil.

8. The method according to any one of claims 3-7, characterized in that, The diesel fuel is selected from one or more combinations of straight-run diesel fuel, catalytic cracking diesel fuel, and hydrotreated diesel fuel; and / or, The diesel fuel has a boiling point of 180~380℃ and a density of less than or equal to 850 kg / m³. 3 .

9. The method according to any one of claims 5 to 7, characterized in that, The heavy oil is wax oil and / or residue oil.

10. The method according to claim 1, characterized in that, The method also includes the following steps prior to step (1): The raw material oil is preheated to a preheating temperature of 200~400℃; The preheating is achieved by heating in a furnace or by exchanging heat between the raw oil and the chemical material obtained from step (3).

11. The method according to claim 10, characterized in that, The preheating temperature is 260~360℃.

12. The method according to any one of claims 1-7, characterized in that, In step (3), the oil-gas separation system is selected from one or more of the following combined: a fractionation column with a theoretical plate number of more than 20, an absorption stabilization system, and a gas separation system; The separation described in step (3) also yields propylene, H2 and C1-C4 alkanes, BTX fraction and methylnaphthalene oil fraction.

13. The method according to any one of claims 1-7, characterized in that, In step (4): The regeneration temperature of the regenerator is 640-780℃, and the pressure is 0.3-0.6MPa; The recycling rate of the regenerated catalyst is 150-200 kg / (m²). 2 ·Second); The regeneration atmosphere in the regenerator is selected from air, oxygen-enriched air, and pure oxygen. The flue gas is returned to the regenerator for recycling after heat exchange, and the temperature of the flue gas returned to the regenerator for recycling is 340-580℃.

14. A system for implementing the method according to any one of claims 1 to 13, characterized in that, The system includes a constant linear velocity fluidized bed reactor (1), a cyclone separator (IV-1), a settling tank (IV), an oil-gas separation system (6), and a regenerator (20). The inner diameter of the reactor outlet section (III) is smaller than that of the reactor reaction section (II). The outlet of the pre-lifting section (I) of the reactor is connected to the inlet of the reaction section (II) of the reactor, and the outlet of the reaction section (II) of the reactor is connected to the inlet of the outlet section (III) of the reactor. The reactor reaction section (II) is a variable diameter reaction section, and the inner diameter of the reactor reaction section (II) gradually decreases from top to bottom; the lower part of the reactor reaction section (II) is provided with a light hydrocarbon feedstock oil inlet (2) and a first atomized steam inlet (3), and the light hydrocarbon feedstock oil inlet (2) and the first atomized steam inlet (3) are connected. The oil outlet of the reactor outlet section (III) is connected to the oil inlet of the cyclone separator (IV-1), the catalyst outlet of the cyclone separator (IV-1) is connected to the inlet of the settler (IV), and the oil and gas outlet of the cyclone separator (IV-1) is connected to the oil and gas inlet of the oil and gas separation system (6). The outlet of the settling tank (IV) is connected to the inlet of the catalyst stripping section (IV-2), the catalyst outlet of the catalyst stripping section (IV-2) is connected to the inlet of the regenerator (20), and the oil and gas outlet of the catalyst stripping section (IV-2) is connected to the oil and gas separation system (6). The regenerator (20) is provided with an oxygen-containing regenerated gas inlet (21) and a flue gas outlet (23). The flue gas outlet (23) and the oxygen-containing regenerated gas inlet (21) are connected through a flue gas circulation system (24). The regenerated catalyst outlet of the regenerator (20) is connected to the catalyst inlet of the pre-lifting section (I) of the reactor through a first regenerator delivery pipeline (22). The bottom of the pre-lifting section (I) of the reactor is provided with a first fluidizing medium inlet (4). The oil-gas separation system (6) is provided with an ethylene outlet (7), a propylene outlet (8), an H2 and C1-C4 alkane outlet (9), a C4 olefin outlet (10), a light gasoline fraction outlet (11), a BTX fraction outlet (12), a heavy aromatics fraction outlet (13), a methylnaphthalene oil fraction outlet (14), and an oil slurry outlet (15). The reactor reaction section (II) is provided with a first heavy feedstock oil inlet (16) and a second atomized steam inlet (17) in the middle, and the reactor reaction section (II) is provided with a first remelting inlet and a second remelting inlet. The C4 olefin outlet (10), the light gasoline fraction outlet (11), and the heavy aromatics fraction outlet (13) are respectively connected to the first recycle inlet or to the light hydrocarbon feedstock inlet (2); the slurry outlet (15) is connected to the second recycle inlet or to the first heavy feedstock inlet (16).

15. The system according to claim 14, characterized in that, The oil and gas outlet of the cyclone separator (IV-1) is connected to the oil and gas inlet of the oil and gas separation system (6) through the reaction oil and gas pipeline (5), and the oil and gas outlet of the catalyst stripping section (IV-2) is connected to the oil and gas inlet of the oil and gas separation system (6) through the reaction oil and gas pipeline (5).

16. The system according to claim 14, characterized in that, The lower part of the catalyst stripping section (IV-2) is provided with a stripping medium inlet (18).

17. The system according to claim 14, characterized in that, The catalyst outlet of the catalyst stripping section (IV-2) is connected to the inlet of the regenerated catalyst of the regenerator (20) through the regenerated catalyst delivery pipeline (19).

18. The system according to claim 14, characterized in that, The first heavy feedstock oil inlet (16) is connected to the second atomizing steam inlet (17).

19. The system according to claim 16, characterized in that, The first refining inlet and the second refining inlet are located below and above the light hydrocarbon feedstock inlet (2), respectively.

20. The system according to any one of claims 14-19, characterized in that, The system is also provided with a riser reactor (25), which is provided with a second heavy feedstock oil inlet (28) and a third atomizing steam inlet (29), and the second heavy feedstock oil inlet (28) and the third atomizing steam inlet (29) are connected. The regenerated catalyst outlet of the regenerator (20) is connected to the catalyst inlet at the bottom of the riser reactor (25) via a second regenerator delivery pipeline (27). The bottom of the riser reactor (25) is also provided with a second fluidizing medium inlet (26).

21. The system according to claim 20, characterized in that, The riser reactor (25) is provided with a third refining port, which is located below the second heavy feedstock inlet (28). The C4 olefin outlet (10), the light gasoline fraction outlet (11), and the heavy aromatics fraction outlet (13) are respectively connected to the third refining port. The slurry outlet (15) is connected to the second heavy feedstock inlet (28).

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