Method and system for increasing yield of chemicals by direct catalytic cracking of crude oil

Abstract

The invention provides a method and system for increasing the yield of chemicals through direct catalytic cracking of crude oil, and the method comprises the following steps: enabling the crude oil to enter a first riser reactor to be in contact with a first catalytic cracking catalyst for catalytic cracking reaction, and carrying out catalyst regeneration cycle; after a product of the first riser reactor is primarily separated by a primary tower, ethylene and propylene are separated from a gas product, light oil in a liquid product enters a second riser reactor to be in contact with a second catalytic cracking catalyst for a deep catalytic cracking reaction, and catalyst regeneration cycle is performed; and after the product of the second riser reactor is separated by a main fractionating tower, the gas product enters an ethylene and propylene separation device to separate ethylene and propylene, and the heavy oil fraction in the liquid product enters an aromatic hydrocarbon extraction unit to extract benzene, toluene and xylene in the heavy oil fraction. By bypassing the traditional oil refining process, all components of the crude oil are directly cracked into low-carbon olefins, aromatic hydrocarbons and other chemicals, and the purpose of producing ethylene, propylene and light aromatic hydrocarbons to the maximum extent can be achieved.

Description

Technical Field

[0001] The present invention relates to a method and system for directly catalytically cracking crude oil to produce multiple chemicals, and belongs to the technical field of petrochemical industry. Background Art

[0002] Light olefins, especially ethylene and propylene, are the core products in the field of petrochemical industry and important organic chemical raw materials. In recent years, under the impact of the rapid development of new energy vehicles, the resource utilization of petroleum has become increasingly important. Using it to produce chemicals and new materials such as light olefins is an inevitable trend in the development of the petrochemical industry. As one of the most promising technologies for preparing light olefins, how to improve the yields of light olefins such as ethylene and propylene and basic chemicals such as BTX has received increasing attention.

[0003] CN116064097A discloses a method and device for catalytic conversion of crude oil to produce light olefins and aromatics. In this method, the separation of crude oil and catalytic cracking are integrated into one design. The crude oil first enters a pressurized crude oil separation tower and is directly subjected to fluid catalytic cracking to produce olefins under pressure. Essentially, this technology still fractionates crude oil into light and heavy components first and then performs steam cracking, and the cracking reactor needs to be redesigned and processed, resulting in an increase in equipment investment costs.

[0004] CN112708455A discloses a method and system for preparing light olefins from crude oil. The core of this method is to use a fluidized bed reactor combined with a riser and a bed to achieve deep catalytic cracking of crude oil. In the product distribution, the yield of propylene is much greater than that of ethylene. In this prior art, the crude oil undergoes vaporization treatment, distillation treatment, and deep catalytic cracking. The cracking efficiency is improved, and the yield of light olefins is also correspondingly increased. However, there are high energy consumption, the same catalyst is used in the first riser and the second riser, and the range of product distribution adjustment is relatively narrow.

[0005] CN112745914A discloses an integrated method for converting crude oil into petrochemical products. In this method, the raw materials are zone-converted in the same system according to hydrocarbon types. Specifically, the crude oil is first flash-separated, the light components are introduced into a cracking furnace for thermal cracking, and the medium and heavy components are introduced into a catalytic cracking unit for catalytic cracking. The catalytic cracking unit includes a riser and two fluidized reactors. The medium components enter the first fluidized bed reactor, and the heavy components enter the first riser reactor. The preliminary cracking products are mixed and then enter the second fluidized bed reactor for catalytic cracking to obtain an oil-gas mixture. After the oil-gas mixture is separated, it is subjected to hydrogenation, reforming, aromatics extraction, etc. to obtain chemical products such as ethylene, propylene, benzene, toluene, and xylene, as well as products such as hydrogenated gasoline. This technology has a high degree of integration and can reduce consumption to a certain extent. However, the operating temperature of this technology is relatively high and the coke yield is high.

[0006] Crude oil has complex components, and there are significant differences in the ease of activation between large and small molecules. In the direct catalytic cracking of the whole fraction / whole components of crude oil, there are problems such as easy coking of the catalyst and low yields of light olefins.

[0007] Therefore, providing a new method and system for directly catalytically cracking crude oil to produce more chemicals has become an urgent technical problem in this field. Summary of the Invention

[0008] To address the above-mentioned drawbacks and deficiencies, one object of the present invention is to provide a method for directly catalytically cracking crude oil to produce more chemicals.

[0009] Another object of the present invention is also to provide a system for directly catalytically cracking crude oil to produce more chemicals for implementing the above-mentioned method for directly catalytically cracking crude oil to produce more chemicals.

[0010] To achieve the above objects, on the one hand, the present invention provides a method for directly catalytically cracking crude oil to produce more chemicals, wherein the method for directly catalytically cracking crude oil to produce more chemicals includes:

[0011] Step (1): Feed the crude oil, i.e., the whole components of crude oil, into the first riser reactor to contact with the first catalytic cracking catalyst for catalytic cracking reaction, and conduct catalyst regeneration and recycling;

[0012] Step (2): After the products of the first riser reactor, i.e., the catalytic cracking products, are preliminarily separated by a pre-fractionating tower, the gas products enter an ethylene and propylene separation unit to separate ethylene and propylene, and the light oil in the liquid products enters the second riser reactor to contact with the second catalytic cracking catalyst for deep catalytic cracking reaction, and conduct catalyst regeneration and recycling;

[0013] Step (3): After the products of the second riser reactor, i.e., the deep catalytic cracking products, are separated by a main fractionating tower, the gas products enter an ethylene and propylene separation unit to separate ethylene and propylene, and the heavy oil fraction in the liquid products enters an aromatics extraction unit to extract benzene, toluene, and xylene therein.

[0014] As a specific embodiment of the above method of the present invention, the method further includes: first subjecting the crude oil to electro-de-salting, then preheating the electro-de-salted crude oil to 220 - 280 °C, and then feeding it into the first riser reactor.

[0015] As a specific embodiment of the above method of the present invention, the method further includes: returning the gasoline fraction and diesel fraction in the liquid products obtained after separation by the main fractionating tower to the second riser reactor and contacting them with the light oil together with the second catalytic cracking catalyst for deep catalytic cracking reaction.

[0016] As a specific embodiment of the method described above in the present invention, the cut range of the gasoline fraction is from the initial boiling point to 200 °C, and the cut range of the diesel fraction is from 200 to 350 °C.

[0017] As a specific embodiment of the method described above in the present invention, the method further includes: returning the slurry obtained after the preliminary separation in the pre-fractionator and / or the slurry obtained after the separation in the main fractionator to the first riser reactor, and contacting the slurry with the crude oil together with the first catalytic cracking catalyst to continue the catalytic cracking reaction.

[0018] As a specific embodiment of the method described above in the present invention, the method further includes: returning the raffinate oil from the aromatics extraction unit to the first riser reactor, and contacting the raffinate oil with the crude oil or a mixture of the crude oil and the slurry together with the first catalytic cracking catalyst to continue the catalytic cracking reaction.

[0019] The method and system provided by the present invention can directly catalytically crack all components of the crude oil into light olefins and BTX. By returning the gasoline fraction and diesel fraction in the liquid product obtained after the separation in the main fractionator to the second riser reactor for recycling, and returning heavy components such as the slurry (the slurry obtained after the preliminary separation in the pre-fractionator and / or the slurry obtained after the separation in the main fractionator) and / or the raffinate oil to the first riser reactor and contacting them with the crude oil together as the feed of the first riser reactor with the first catalytic cracking catalyst to continue the catalytic cracking reaction, the production of ethylene, propylene and light aromatics can be maximized, that is, the purpose of maximizing the chemical yield can be achieved.

[0020] As a specific embodiment of the method described above in the present invention, the crude oil includes at least one of paraffinic crude oil, intermediate crude oil, naphthenic crude oil, wax oil and atmospheric residue, etc., and a mixed oil obtained by blending at least one of hydrocracking tail oil, coal pyrolysis oil, shale oil and vacuum gas oil into the above at least one crude oil; preferably, the crude oil is paraffinic crude oil.

[0021] As a specific embodiment of the method described above in the present invention, in step (1), the reaction temperature of the catalytic cracking reaction is 550 - 600 °C, the catalyst-to-oil weight ratio is 4 - 20:1, and the temperature of catalyst regeneration is 650 - 750 °C. Preferably, in step (1), the reaction temperature of the catalytic cracking reaction is 580 - 600 °C, and the catalyst-to-oil weight ratio is 10 - 20:1.

[0022] As a specific embodiment of the method described above in the present invention, the first catalytic cracking catalyst includes a matrix and a catalytically active component. Based on the total weight of the first catalytic cracking catalyst being 100%, the content of the catalytically active component is 15 - 35%, and the rest is the matrix;

[0023] The catalytically active components include a mixture of ZSM-5, USY, etc. The present invention does not make specific requirements on the specific substances of the matrix in the first catalytic cracking catalyst, the mass ratio of ZSM-5 to USY, etc., and can be reasonably selected and adjusted according to the actual on-site operation needs. For example, in some embodiments of the present invention, the matrix can be kaolin, etc., and the mass ratio of ZSM-5 to USY can be 3:2, etc.

[0024] As a specific embodiment of the method described above in the present invention, in step (2), the reaction temperature of the deep catalytic cracking reaction is 580 - 650 °C, the catalyst-to-oil weight ratio is 8 - 30:1, and the temperature of catalyst regeneration is 680 - 780 °C. Preferably, in step (2), the reaction temperature of the deep catalytic cracking reaction is 600 - 650 °C, and the catalyst-to-oil weight ratio is 15 - 30:1.

[0025] As a specific embodiment of the method described above in the present invention, the feed rates of the first riser reactor and the second riser reactor are respectively 0.3 - 3 kg / h, and the catalyst inventories are respectively 8 - 10 kg.

[0026] The temperatures in the first riser reactor and the second riser reactor used in the present invention are distributed in a gradient manner, and the present invention takes the reactor outlet temperature as the reaction temperature.

[0027] The method for directly catalytically cracking crude oil to produce more chemicals provided by the present invention can achieve the zonal conversion of all components of crude oil (realize the zonal conversion of different fractions) through appropriate regulation of catalytic cracking reaction conditions such as the reaction temperature and catalyst-to-oil weight ratio of the two-stage riser reactor, maximize the production of chemicals such as light olefins and aromatics, and avoid the dilemma that small molecules do not crack while large molecules undergo condensation and carbon deposition due to the difference in the activation difficulty of large and small molecules in crude oil, making it difficult to achieve both good catalyst activity and anti-carbon deposition performance.

[0028] As a specific embodiment of the method described above in the present invention, the second catalytic cracking catalyst includes a matrix and catalytically active components. Based on the total weight of the second catalytic cracking catalyst being 100%, the content of the catalytically active components is 20 - 40%, and the rest is the matrix;

[0029] The catalytically active components include a mixture of USY, ZSM-5 modified with rare earth metals, etc. The present invention does not make specific requirements on the specific substances of the matrix in the second catalytic cracking catalyst, the mass ratio of USY to ZSM-5 modified with rare earth metals, etc., and can be reasonably selected and adjusted according to the actual on-site operation needs. For example, in some embodiments of the present invention, the matrix can be kaolin, etc., and the mass ratio of the ZSM-5 molecular sieve modified with rare earth metals to the USY molecular sieve is 2:1, etc.

[0030] The first catalytic cracking catalyst and the second catalytic cracking catalyst used in the method for directly catalytic cracking crude oil to produce multiple chemicals provided by the present invention are two catalysts with different catalytic active components. Using two different catalysts can give full play to the advantages of both catalysts.

[0031] As a specific embodiment of the method described above in the present invention, the rare earth metal includes at least one of scandium (Sc), yttrium (Y), lanthanum (La), cerium (Ce), etc. The present invention does not make specific requirements on the content of rare earth metals in the rare earth metal-modified ZSM-5, and its dosage can be reasonably adjusted according to the actual on-site operation needs. For example, in some embodiments of the present invention, calculated by rare earth metal elements, the rare earth metal accounts for 0.5% of the mass of the ZSM-5 molecular sieve.

[0032] On the other hand, the present invention also provides a system for directly catalytic cracking crude oil to produce multiple chemicals for implementing the method for directly catalytic cracking crude oil to produce multiple chemicals described above. The system includes:

[0033] A first riser reactor-regenerator, a pre-fractionating tower, a second riser reactor-regenerator, a main fractionating tower, an aromatics extraction unit, and an ethylene and propylene separation device; wherein, the first riser reactor-regenerator includes a first riser reactor and a first regenerator, the second riser reactor-regenerator includes a second riser reactor and a second regenerator, and the ethylene and propylene separation device includes a propylene separation device and an ethylene separation device connected in sequence;

[0034] The outlet of the first riser reactor-regenerator is connected to the inlet of the pre-fractionating tower through a pipeline, the gas outlet of the pre-fractionating tower is connected to the inlet of the propylene separation device through a pipeline, the light oil outlet of the pre-fractionating tower is connected to the inlet of the second riser reactor-regenerator through a pipeline, the outlet of the second riser reactor-regenerator is connected to the inlet of the main fractionating tower through a pipeline, the heavy oil fraction outlet of the main fractionating tower is connected to the inlet of the aromatics extraction unit through a pipeline, and the gas outlet of the main fractionating tower is connected to the inlet of the propylene separation device through a pipeline.

[0035] As a specific embodiment of the system described above in the present invention, the gasoline fraction and diesel fraction outlets of the main fractionating tower are connected to the inlet of the second riser reactor-regenerator through a pipeline.

[0036] As a specific embodiment of the system described above in the present invention, the slurry outlet of the pre-fractionating tower and / or the slurry outlet of the main fractionating tower are connected to the inlet of the first riser reactor-regenerator through a pipeline.

[0037] As a specific embodiment of the system described above in the present invention, the outlet of the raffinate oil of the aromatics extraction unit is connected to the inlet of the first riser reactor-regenerator through a pipeline.

[0038] Compared with the prior art, the beneficial technical effects that can be achieved by the present invention include:

[0039] (1) The method and system for directly catalytic cracking of crude oil to produce multiple chemicals provided by the present invention bypass the traditional refining process, directly crack the whole components of crude oil into chemicals such as low-carbon olefins and aromatics, maximize the utilization of the resource properties of crude oil, simplify the process flow, reduce equipment investment and energy consumption. In addition, the present invention transforms the product oil fuel into chemicals, directly reducing carbon emissions from the source.

[0040] (2) The method and system for directly catalytic cracking of crude oil to produce multiple chemicals provided by the present invention adopt a series connection mode of two-stage riser reactors, use different catalysts respectively and regenerate the catalysts separately, which can give full play to the advantages of the two catalysts, so as to realize the partition conversion of the whole components of crude oil (realize the partition conversion of different fractions), maximize the production of chemicals such as low-carbon olefins and aromatics, and avoid the dilemma that small molecules do not crack and large molecules condense and deposit carbon due to the difference in the activation difficulty of large and small molecules in crude oil, making it difficult to achieve both catalyst activity and anti-carbon deposition performance.

[0041] (3) In the method and system for directly catalytic cracking of crude oil to produce multiple chemicals provided by the present invention, the whole components of crude oil are fed and the cracked fraction oils, such as gasoline fraction and diesel fraction, are recycled, which greatly improves the yield of low-carbon olefins. Among them, the sum of the yields of ethylene, propylene and butene can reach more than 50% at most, providing a new strategy for the green, low-carbon and high-quality development of the petrochemical industry. Description of the Drawings

[0042] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0043] Figure 1 It is a schematic structural diagram of the system for directly catalytic cracking of crude oil to produce multiple chemicals provided by the embodiment of the present invention.

[0044] Main reference numeral descriptions:

[0045] 1 - Crude oil, 2 - First riser reactor regeneration unit, 3 - Atmospheric distillation tower, 4 - Light oil, 5 - Second riser reactor regeneration unit, 6 - Main fractionation tower, 7 - Gasoline fraction and diesel fraction, 8 - Heavy oil fraction, 9 - Aromatic extraction unit, 10 - Benzene, toluene and xylene, i.e., BTX, 11 - Raffinate oil, 12 - Slurry oil, 13 - Light hydrocarbon, 14 - Propylene separation device, 15 - Propylene, 16 - Ethylene separation device, 17 - Ethylene and 18 - Dry gas. Detailed implementation manners

[0046] It should be noted that the term "comprising" and any variations thereof in the specification and claims of the present invention and the above-mentioned drawings are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device comprising a series of steps or units does not necessarily limit to those clearly listed steps or units, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0047] The "range" disclosed in the present invention is given in the form of a lower limit and an upper limit. There can be one or more lower limits, and one or more upper limits. A given range is defined by selecting a lower limit and an upper limit. The selected lower limit and upper limit define the boundary of a particular range. All ranges defined in this way are combinable, that is, any lower limit can be combined with any upper limit to form a range. For example, ranges of 60 - 120 and 80 - 110 are listed for a specific parameter, it is understood that ranges of 60 - 110 and 80 - 120 are also anticipated. In addition, if the minimum range values listed are 1 and 2, and the maximum range values listed are 3, 4 and 5, then the following ranges are all anticipated: 1 - 3, 1 - 4, 1 - 5, 2 - 3, 2 - 4 and 2 - 5.

[0048] In the present invention, unless otherwise specified, the numerical range "a - b" represents an abbreviated representation of any real number combination between a and b, where both a and b are real numbers. For example, the numerical range "0 - 5" means that all real numbers between "0 - 5" are fully listed in the present invention, and "0 - 5" is only an abbreviated representation of these numerical combinations.

[0049] In the present invention, if there is no special description, all the implementation manners and preferred implementation manners mentioned in the present invention can be combined with each other to form a new technical solution.

[0050] In the present invention, if there is no special description, all the technical features and preferred features mentioned in the present invention can be combined with each other to form a new technical solution.

[0051] In the present invention, unless otherwise specified, the term "two" used in this specification means "at least two".

[0052] In the present invention, unless otherwise specified, all steps mentioned herein can be carried out in sequence or randomly, but preferably in sequence. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) carried out in sequence, or may also include steps (b) and (a) carried out in sequence. For example, it is mentioned that the method may further include step (c), indicating that step (c) can be added to the method in any order. For example, the method may include steps (a), (b) and (c), or may also include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0053] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the attached tables, drawings and embodiments. The following described embodiments are some, but not all, of the embodiments of the present invention, and are only used to illustrate the present invention and should not be construed as limiting the scope of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts fall within the scope of protection of the present invention. For those conditions not specified in the embodiments, they are carried out according to the conventional conditions or the conditions recommended by the manufacturer. For the reagents or instruments whose manufacturers are not specified, they are all conventional products that can be obtained through commercial purchase.

[0054] System embodiment

[0055] Embodiment 1

[0056] This embodiment provides a system for directly catalytic cracking of crude oil to produce multiple chemicals. Among them, the structural schematic diagram of the system is as Figure 1 shown. It can be seen from Figure 1 that the system includes:

[0057] A first riser reactor-regenerator 2, a pre-fractionating tower 3, a second riser reactor-regenerator 5, a main fractionating tower 6, an aromatics extraction unit 9, and an ethylene and propylene separation device; among them, the first riser reactor-regenerator 2 includes a first riser reactor and a first regenerator, the second riser reactor-regenerator 5 includes a second riser reactor and a second regenerator, and the ethylene and propylene separation device includes a propylene separation device 14 and an ethylene separation device 16 connected in sequence;

[0058] The outlet of the first riser reactor regeneration unit 2 is connected to the inlet of the atmospheric distillation column 3 through a pipeline. The gas outlet of the atmospheric distillation column 3 is connected to the inlet of the propylene separation unit 14 through a pipeline. The light oil outlet of the atmospheric distillation column 3 is connected to the inlet of the second riser reactor regeneration unit 5 through a pipeline. The outlet of the second riser reactor regeneration unit 5 is connected to the inlet of the main fractionation column 6 through a pipeline. The heavy oil fraction outlet of the main fractionation column 6 is connected to the inlet of the aromatics extraction unit 9 through a pipeline. The gas outlet of the main fractionation column 6 is connected to the inlet of the propylene separation unit 14 through a pipeline;

[0059] The gasoline fraction and diesel fraction outlets of the main fractionation column 6 are connected to the inlet of the second riser reactor regeneration unit 5 through a pipeline;

[0060] The slurry oil outlet of the atmospheric distillation column 3 and the slurry oil outlet of the main fractionation column 6 are respectively connected to the inlet of the first riser reactor regeneration unit 2 through a pipeline;

[0061] The outlet of the raffinate oil of the aromatics extraction unit 9 is connected to the inlet of the first riser reactor regeneration unit 2 through a pipeline.

[0062] Method Example

[0063] Example 2

[0064] This example provides a method for directly catalytic cracking of crude oil to produce more chemicals, which is realized by using the system for directly catalytic cracking of crude oil to produce more chemicals provided in Example 1, and includes the following specific steps:

[0065] The whole components of the desalted crude oil 1 (1# crude oil) are preheated to 280 °C, and then enter the first riser reactor through the raw material atomizing nozzle to contact with the first catalytic cracking catalyst for catalytic cracking reaction, and the catalyst regeneration cycle is carried out. Among them, the reaction outlet temperature of the first riser reactor is controlled at 580 °C, and the catalyst-to-oil weight ratio is 10:1. The first catalytic cracking catalyst includes a matrix and a catalytic active component. Based on the total weight of the first catalytic cracking catalyst being 100%, the content of the catalytic active component is 30%, and the rest is the matrix (kaolin). The catalytic active component is a mixture of ZSM-5 molecular sieve and USY molecular sieve, and the mass ratio of the two is 3:2. Both ZSM-5 molecular sieve and USY molecular sieve are purchased from Nankai Catalyst Factory, and the temperature of catalyst regeneration is 700 °C.

[0066] The product of the first riser reactor, i.e., the catalytic cracking product, after being preliminarily separated by the debutanizer 3, the gas product, i.e., the light hydrocarbon 13, enters the ethylene and propylene separation unit to separate ethylene and propylene. The light oil 4 in the liquid product enters the second riser reactor to contact with the second catalytic cracking catalyst for deep catalytic cracking reaction, and catalyst regeneration and recycling are carried out. Among them, the reaction outlet temperature of the second riser reactor is controlled at 600 °C, and the catalyst-to-oil weight ratio is 15:1. The second catalytic cracking catalyst includes a matrix and a catalytic active component. Based on the total weight of the second catalytic cracking catalyst being 100%, the content of the catalytic active component is 35%, and the rest is the matrix (kaolin). The catalytic active component is a mixture of USY zeolite and rare earth metal-modified ZSM-5 zeolite. The mass ratio of the rare earth metal-modified ZSM-5 zeolite to the USY zeolite is 2:1. Among them, the rare earth metal is Ce. Calculated by Ce element, Ce accounts for 0.5% of the mass of the ZSM-5 zeolite, and the temperature of catalyst regeneration is 710 °C.

[0067] In this embodiment, the feed rate of the first riser reactor (the feed rate in the present invention refers to the mass of all raw materials entering the reactor per hour) is 1 kg / h, and the inventory of the first catalytic cracking catalyst is 10 kg; the feed rate of the second riser reactor is 0.3 kg / h, and the inventory of the second catalytic cracking catalyst is 8 kg.

[0068] The product of the second riser reactor, i.e., the deep catalytic cracking product, after being separated by the main fractionator 6, the gas product, i.e., the light hydrocarbon 13, enters the ethylene and propylene separation unit to separate ethylene and propylene. The gasoline fraction and diesel fraction 7 in the liquid product return to the second riser reactor to continue the deep catalytic cracking reaction. Among them, the cut range of the gasoline fraction is initial boiling point - 200 °C, and the cut range of the diesel fraction is 200 - 350 °C. The heavy oil fraction 8 with poor cracking activity in the liquid product enters the aromatics extraction unit 9 to extract benzene, toluene, and xylene therein, i.e., BTX 10, and the raffinate 11 returns to the first riser reactor to be used as a raw material together with the crude oil 1 to continue the catalytic cracking reaction;

[0069] The slurry 12 obtained after the preliminary separation by the debutanizer 3 and the slurry 12 obtained after the separation by the main fractionator 6 return to the first riser reactor and contact with the first catalytic cracking catalyst together with the crude oil for catalytic cracking reaction.

[0070] Among them, the 1# crude oil is paraffin-based crude oil, and its basic physical property data are shown in Table 1 below. The reaction conditions of the first riser reactor and the second riser reactor in this embodiment and the product distribution situation obtained in this embodiment are listed in Table 2.

[0071] Example 3

[0072] This embodiment provides a method for directly catalytically cracking crude oil to produce multiple chemicals, which is realized by using the system for directly catalytically cracking crude oil to produce multiple chemicals provided in Embodiment 1, and includes the following specific steps:

[0073] The whole components of the desalted crude oil 1 (2# crude oil) are preheated to 250°C, and then enter the first riser reactor through the raw material atomizing nozzle to contact with the first catalytic cracking catalyst for catalytic cracking reaction, and catalyst regeneration cycle is carried out. Among them, the reaction outlet temperature of the first riser reactor is controlled at 580°C, and the catalyst-oil weight ratio is 10:1. The first catalytic cracking catalyst includes a matrix and a catalytic active component. Based on the total weight of the first catalytic cracking catalyst being 100%, the content of the catalytic active component is 30%, and the rest is the matrix (kaolin). The catalytic active component is a mixture of ZSM-5 molecular sieve and USY molecular sieve, and the mass ratio of the two is 3:2. Both ZSM-5 molecular sieve and USY molecular sieve are purchased from Nankai Catalyst Factory, and the temperature of catalyst regeneration is 700°C.

[0074] The product of the first riser reactor, that is, the catalytic cracking product, after being preliminarily separated by the debutanizer 3, the gas product, that is, the light hydrocarbon 13, enters the ethylene and propylene separation device to separate ethylene and propylene. The light oil 4 in the liquid product enters the second riser reactor to contact with the second catalytic cracking catalyst for deep catalytic cracking reaction, and catalyst regeneration cycle is carried out. Among them, the reaction outlet temperature of the second riser reactor is controlled at 600°C, and the catalyst-oil weight ratio is 15:1. The second catalytic cracking catalyst includes a matrix and a catalytic active component. Based on the total weight of the second catalytic cracking catalyst being 100%, the content of the catalytic active component is 35%, and the rest is the matrix (kaolin). The catalytic active component is a mixture of USY molecular sieve and rare earth metal modified ZSM-5 molecular sieve, and the mass ratio of the rare earth metal modified ZSM-5 molecular sieve to USY molecular sieve is 2:1. Among them, the rare earth metal is Y, and calculated by Y element, Y accounts for 0.5% of the mass of ZSM-5 molecular sieve, and the temperature of catalyst regeneration is 710°C.

[0075] The feed rate of the first riser reactor in this embodiment is 1 kg / h, and the inventory of the first catalytic cracking catalyst is 10 kg; the feed rate of the second riser reactor is 0.3 kg / h, and the inventory of the second catalytic cracking catalyst is 8 kg.

[0076] After the products of the second riser reactor, i.e., the deep catalytic cracking products, are separated by the main fractionating tower 6, the gas products, i.e., the light hydrocarbons 13, enter the ethylene and propylene separation unit to separate ethylene and propylene. The gasoline fraction and diesel fraction 7 in the liquid products are returned to the second riser reactor to continue the deep catalytic cracking reaction. The cut range of the gasoline fraction is from the initial boiling point to 200 °C, and the cut range of the diesel fraction is 200 - 350 °C. The heavy oil fraction 8 with poor cracking activity in the liquid products enters the aromatics extraction unit 9 to extract benzene, toluene, and xylene, i.e., BTX 10. The raffinate oil 11 is returned to the first riser reactor and used as a raw material together with the crude oil 1 to continue the catalytic cracking reaction;

[0077] The slurry 12 obtained after the preliminary separation by the debutanizer 3 and the slurry 12 obtained after the separation by the main fractionating tower 6 are returned to the first riser reactor and contact the first catalytic cracking catalyst together with the crude oil to carry out the catalytic cracking reaction.

[0078] Among them, the 2# crude oil is paraffin-based crude oil, and its basic physical property data are shown in Table 1 below. The reaction conditions of the first riser reactor and the second riser reactor in this example and the product distribution of this example are listed in Table 2.

[0079] Example 4

[0080] This example provides a method for directly catalytic cracking crude oil to produce multiple chemicals, which is realized by using the system for directly catalytic cracking crude oil to produce multiple chemicals provided in Example 1, and includes the following specific steps:

[0081] The desalted crude oil 1 (1# crude oil) is mixed with desalted wax oil for feeding, and the mass ratio of the two is 2:1. The mixture is preheated to 280 °C and enters the first riser reactor through the raw material atomizing nozzle to contact the first catalytic cracking catalyst for catalytic cracking reaction, and the catalyst regeneration cycle is carried out. The reaction outlet temperature of the first riser reactor is controlled at 600 °C, and the catalyst-to-oil weight ratio is 15:1. The first catalytic cracking catalyst includes a matrix and a catalytic active component. Based on the total weight of the first catalytic cracking catalyst being 100%, the content of the catalytic active component is 30%, and the rest is the matrix (kaolin). The catalytic active component is a mixture of ZSM-5 molecular sieve and USY molecular sieve, and the mass ratio of the two is 3:2. Both the ZSM-5 molecular sieve and the USY molecular sieve are purchased from Nankai Catalyst Factory, and the temperature of catalyst regeneration is 710 °C.

[0082] The product of the first riser reactor, i.e., the catalytic cracking product, after being preliminarily separated by the debutanizer 3, the gas product, i.e., the light hydrocarbon 13, enters the ethylene and propylene separation unit to separate ethylene and propylene. The light oil 4 in the liquid product enters the second riser reactor to contact with the second catalytic cracking catalyst for deep catalytic cracking reaction, and the catalyst regeneration cycle is carried out. Among them, the reaction outlet temperature of the second riser reactor is controlled at 620 °C, and the catalyst-to-oil weight ratio is 20:1. The second catalytic cracking catalyst includes a matrix and a catalytic active component. Based on the total weight of the second catalytic cracking catalyst being 100%, the content of the catalytic active component is 35%, and the rest is the matrix. The catalytic active component is a mixture of USY molecular sieve and rare earth metal modified ZSM-5 molecular sieve. The mass ratio of the rare earth metal modified ZSM-5 molecular sieve to the USY molecular sieve is 2:1. Among them, the rare earth metal is Ce. Calculated by Ce element, Ce accounts for 0.5% of the mass of the ZSM-5 molecular sieve, and the temperature of catalyst regeneration is 720 °C.

[0083] In this embodiment, the feed rate of the first riser reactor is 1 kg / h, and the inventory of the first catalytic cracking catalyst is 10 kg; the feed rate of the second riser reactor is 0.3 kg / h, and the inventory of the second catalytic cracking catalyst is 8 kg.

[0084] The product of the second riser reactor, i.e., the deep catalytic cracking product, after being separated by the main fractionator 6, the gas product, i.e., the light hydrocarbon 13, enters the ethylene and propylene separation unit to separate ethylene and propylene. The gasoline fraction and diesel fraction 7 in the liquid product return to the second riser reactor to continue the deep catalytic cracking reaction. Among them, the cutting range of the gasoline fraction is from the initial boiling point to 200 °C, and the cutting range of the diesel fraction is 200 - 350 °C. The heavy oil fraction 8 with poor cracking activity in the liquid product enters the aromatics extraction unit 9 to extract benzene, toluene, and xylene therein, i.e., BTX 10, and the raffinate 11 returns to the first riser reactor to be used as a raw material together with the crude oil 1 to continue the catalytic cracking reaction;

[0085] The slurry 12 obtained after the preliminary separation by the debutanizer 3 and the slurry 12 obtained after the separation by the main fractionator 6 return to the first riser reactor and contact with the first catalytic cracking catalyst together with the crude oil for catalytic cracking reaction.

[0086] Among them, both the 1# crude oil and the wax oil are paraffin-based crude oils, and their basic physical property data are shown in Table 1 below. The reaction conditions of the first riser reactor and the second riser reactor in this embodiment and the product distribution obtained in this embodiment are listed in Table 2.

[0087] Example 5

[0088] This embodiment provides a method for directly catalytically cracking crude oil to produce multiple chemicals, which is realized by using the system for directly catalytically cracking crude oil to produce multiple chemicals provided in Embodiment 1, and includes the following specific steps:

[0089] The whole components of the desalted crude oil 1 (1# crude oil) are preheated to 220 °C, and then enter the first riser reactor through the raw material atomizing nozzle to contact with the first catalytic cracking catalyst for catalytic cracking reaction, and catalyst regeneration cycle is carried out. The reaction outlet temperature of the first riser reactor is controlled at 550 °C, and the catalyst-to-oil weight ratio is 4:1. The first catalytic cracking catalyst includes a matrix and a catalytic active component. Based on the total weight of the first catalytic cracking catalyst being 100%, the content of the catalytic active component is 30%, and the rest is the matrix. The catalytic active component is a mixture of ZSM-5 molecular sieve and USY molecular sieve, in which the mass ratio of ZSM-5 molecular sieve to USY molecular sieve is 3:2. The matrix is kaolin. Both ZSM-5 molecular sieve and USY molecular sieve are purchased from Nankai Catalyst Factory, and the temperature of catalyst regeneration is 710 °C.

[0090] The product of the first riser reactor, that is, the catalytic cracking product, after being preliminarily separated by the debutanizer 3, the gas product, that is, the light hydrocarbon 13, enters the ethylene and propylene separation device to separate ethylene and propylene. The light oil 4 in the liquid product enters the second riser reactor to contact with the second catalytic cracking catalyst for deep catalytic cracking reaction, and catalyst regeneration cycle is carried out. Among them, the reaction outlet temperature of the second riser reactor is controlled at 580 °C, and the catalyst-to-oil weight ratio is 8:1. The second catalytic cracking catalyst includes a matrix and a catalytic active component. Based on the total weight of the second catalytic cracking catalyst being 100%, the content of the catalytic active component is 35%, and the rest is the matrix. The catalytic active component is a mixture of USY molecular sieve and rare earth metal modified ZSM-5 molecular sieve, in which the mass ratio of rare earth metal modified ZSM-5 molecular sieve to USY molecular sieve is 2:1. The matrix is kaolin, and the rare earth metal is Ce. Calculated by Ce element, Ce accounts for 0.5% of the mass of ZSM-5 molecular sieve, and the temperature of catalyst regeneration is 720 °C.

[0091] The feed rate of the first riser reactor in this embodiment is 1 kg / h, and the inventory of the first catalytic cracking catalyst is 10 kg; the feed rate of the second riser reactor is 0.3 kg / h, and the inventory of the second catalytic cracking catalyst is 8 kg.

[0092] After the products of the second riser reactor, i.e., the deep catalytic cracking products, are separated by the main fractionating tower 6, the gas products, i.e., the light hydrocarbons 13, enter the ethylene and propylene separation unit to separate ethylene and propylene. The gasoline fraction and diesel fraction 7 in the liquid products are returned to the second riser reactor to continue the deep catalytic cracking reaction. The cut range of the gasoline fraction is from the initial boiling point to 200 °C, and the cut range of the diesel fraction is 200 - 350 °C. The heavy oil fraction 8 with poor cracking activity in the liquid products enters the aromatics extraction unit 9 to extract benzene, toluene, and xylene, i.e., BTX 10. The raffinate 11 is returned to the first riser reactor and used as a raw material together with the crude oil 1 to continue the catalytic cracking reaction;

[0093] The slurry 12 obtained after the preliminary separation by the pre-fractionating tower 3 and the slurry 12 obtained after the separation by the main fractionating tower 6 are returned to the first riser reactor and contact the first catalytic cracking catalyst together with the crude oil for catalytic cracking reaction.

[0094] Among them, the 1# crude oil is paraffin-based crude oil, and its basic physical property data are shown in Table 1 below. The reaction conditions of the first riser reactor and the second riser reactor in this example and the product distribution of this example are listed in Table 2.

[0095] Example 6

[0096] This example provides a method for directly catalytic cracking of crude oil to produce multiple chemicals, which is realized by using the system for directly catalytic cracking of crude oil to produce multiple chemicals provided in Example 1, and includes the following specific steps:

[0097] The whole components of the desalted crude oil 1 (1# crude oil) are preheated to 220 °C and enter the first riser reactor through the raw material atomizing nozzle to contact the first catalytic cracking catalyst for catalytic cracking reaction, and the catalyst regeneration cycle is carried out. The reaction outlet temperature of the first riser reactor is controlled at 600 °C, and the catalyst-to-oil weight ratio is 20:1. The first catalytic cracking catalyst includes a matrix and a catalytic active component. Based on the total weight of the first catalytic cracking catalyst being 100%, the content of the catalytic active component is 35%, and the rest is the matrix. The catalytic active component is a mixture of ZSM-5 molecular sieve and USY molecular sieve, in which the mass ratio of ZSM-5 molecular sieve to USY molecular sieve is 3:2. The matrix is kaolin. Both ZSM-5 molecular sieve and USY molecular sieve are purchased from Nankai Catalyst Factory, and the temperature of catalyst regeneration is 710 °C.

[0098] The product of the first riser reactor, i.e., the catalytic cracking product, after being preliminarily separated by the debutanizer 3, the gas product, i.e., the light hydrocarbon 13, enters the ethylene and propylene separation unit to separate ethylene and propylene. The light oil 4 in the liquid product enters the second riser reactor to contact with the second catalytic cracking catalyst for deep catalytic cracking reaction, and catalyst regeneration and recycling are carried out. Among them, the reaction outlet temperature of the second riser reactor is controlled at 650 °C, and the catalyst-to-oil weight ratio is 30:1. The second catalytic cracking catalyst includes a matrix and a catalytic active component. Based on the total weight of the second catalytic cracking catalyst being 100%, the content of the catalytic active component is 40%, and the rest is the matrix. The catalytic active component is a mixture of USY molecular sieve and rare earth metal modified ZSM-5 molecular sieve. Among them, the mass ratio of the rare earth metal modified ZSM-5 molecular sieve to the USY molecular sieve is 2:1. The matrix is kaolin, and the rare earth metal is La. Calculated by La element, La accounts for 0.5% of the mass of the ZSM-5 molecular sieve, and the temperature of catalyst regeneration is 720 °C.

[0099] In this example, the feed rate of the first riser reactor is 1 kg / h, and the inventory of the first catalytic cracking catalyst is 10 kg; the feed rate of the second riser reactor is 0.3 kg / h, and the inventory of the second catalytic cracking catalyst is 8 kg.

[0100] The product of the second riser reactor, i.e., the deep catalytic cracking product, after being separated by the main fractionator 6, the gas product, i.e., the light hydrocarbon 13, enters the ethylene and propylene separation unit to separate ethylene and propylene. The gasoline fraction and diesel fraction 7 in the liquid product return to the second riser reactor to continue the deep catalytic cracking reaction. Among them, the cut range of the gasoline fraction is initial boiling point - 200 °C, and the cut range of the diesel fraction is 200 - 350 °C. The heavy oil fraction 8 with poor cracking activity in the liquid product enters the aromatics extraction unit 9 to extract benzene, toluene, and xylene therein, i.e., BTX 10, and the raffinate 11 returns to the first riser reactor to continue the catalytic cracking reaction with the crude oil 1 as the raw material;

[0101] The slurry 12 obtained after the preliminary separation by the debutanizer 3 and the slurry 12 obtained after the separation by the main fractionator 6 return to the first riser reactor and contact with the first catalytic cracking catalyst together with the crude oil for catalytic cracking reaction.

[0102] Among them, the 1# crude oil is paraffin-based crude oil, and its basic physical property data is shown in Table 1 below. The reaction conditions of the first riser reactor and the second riser reactor in this example and the product distribution of this example are listed in Table 2.

[0103] Comparative Example 1

[0104] This comparative example provides a method for directly catalytically cracking crude oil to produce multiple chemicals. In this method, the crude oil passes through the first riser reactor once, and the light components of the main fractionation tower are not recycled. The method includes the following specific steps:

[0105] The whole components of the desalted crude oil (1# crude oil) are preheated to 280 °C, and then enter the first riser reactor through the raw material atomizing nozzle to contact with the first catalytic cracking catalyst for catalytic cracking reaction, and the catalyst regeneration cycle is carried out. The reaction outlet temperature of the first riser reactor is controlled at 600 °C, and the catalyst-to-oil weight ratio is 20:1. The first catalytic cracking catalyst includes a matrix and a catalytic active component. Based on the total weight of the first catalytic cracking catalyst being 100%, the content of the catalytic active component is 30%, and the rest is the matrix (kaolin). The catalytic active component is a mixture of ZSM-5 molecular sieve and USY molecular sieve, and the mass ratio of the two is 3:2. Both ZSM-5 molecular sieve and USY molecular sieve are purchased from Nankai Catalyst Factory, and the temperature of catalyst regeneration is 700 °C.

[0106] The products of the first riser reactor, that is, the catalytic cracking products, are preliminarily separated by the pre-fractionating tower. The gas products, that is, the light hydrocarbons, enter the ethylene and propylene separation unit to separate ethylene and propylene. After the light oil in the liquid products enters the main fractionating tower for separation, the gas products, that is, the light hydrocarbons, also enter the ethylene and propylene separation unit to separate ethylene and propylene. All the liquid products enter the aromatics extraction unit together to extract benzene, toluene and xylene, that is, BTX, therein.

[0107] In this comparative example, the feed rate of the first riser reactor is 1 kg / h, and the inventory of the first catalytic cracking catalyst is 10 kg.

[0108] Among them, 1# crude oil is paraffin-based crude oil, and its basic physical property data is shown in Table 1 below. The reaction conditions of the first riser reactor in this comparative example and the product distribution obtained in this comparative example are listed in Table 2.

[0109] Table 1 Basic physical property data of catalytic cracking raw materials

[0110] Analysis item 1# Crude oil 2# Crude oil Wax oil API gravity 31.6 30.1 -- <![CDATA[Density (20 °C, g / cm 3 )]]> 0.87 0.86 0.87 Distillation range (℃) IBP 158.0 158.1 -- 10％ 267.3 256.7 -- 30％ 397.6 355.4 449.3 50％ 524.5 449.6 463.4 70％ 605.4 548.6 478.6 90％ 701.1 661.6 504.5 FBP 825.9 816.1 544.9

[0111] Table 2 Catalytic cracking process parameters and product distribution

[0112]

[0113]

[0114] As can be seen from Table 2, in the embodiments of the present invention, the whole components of crude oil are directly subjected to catalytic cracking, and by recycling the cracked liquid products, that is, the gasoline fraction and diesel fraction in the liquid products separated by the main fractionation column, the chemical yield can be effectively improved. In addition, by optimizing the operating conditions such as the reaction temperature and catalyst-to-oil weight ratio of the first riser reactor and the second riser reactor and matching a suitable catalyst (specifically, taking Example 6 as an example, wherein the reactants in the second riser reactor are the light oil obtained by catalytic cracking of the whole components of crude oil in the first riser reactor, the recycled gasoline fraction and diesel fraction. These reactants have relatively small molecular weights and high activation energies, and require more ZSM-5 molecular sieves with high cracking activity. Correspondingly, the content of rare earth metal modified ZSM-5 molecular sieve in the second catalytic cracking catalyst is 26.7%; compared with the second riser reactor, the raw material in the first riser reactor is the whole components of crude oil, and the molecular weight distribution of the whole components of crude oil is wide, and the macromolecules in it are prone to coking. Correspondingly, the content of ZSM-5 molecular sieve in the catalyst used, that is, the first catalytic cracking catalyst, is correspondingly reduced, and the content of ZSM-5 molecular sieve is 21%), the chemical yield such as light olefins can also be effectively improved.

[0115] Specifically, under the same or similar operating conditions, compared with Comparative Example 1, the chemical yield (triolefins + BTX) in the embodiments of the present invention is higher. By comparing Example 5 with other examples, it can be seen that the reaction temperature and catalyst-to-oil ratio of the first riser reactor and the second riser reactor affect the product yield. Specifically, when the reaction temperature and catalyst-to-oil ratio of the first riser reactor and the second riser reactor are relatively high, it is beneficial to improve the chemical yield (triolefins + BTX).

[0116] As described above, the above are only specific embodiments of the present invention, and the scope of the invention implementation cannot be limited by them. Therefore, the replacement of equivalent components or equivalent changes and modifications made according to the scope of the present invention patent protection should still fall within the scope covered by this patent. In addition, the technical features in the present invention can be freely combined with each other between technical features, between technical features and technical inventions, and between technical inventions.

Claims

1. A method for directly catalytic cracking of crude oil to produce multiple chemicals, characterized in that, the method for directly catalytic cracking of crude oil to produce multiple chemicals includes: Step (1): Feed the crude oil into a first riser reactor to contact with a first catalytic cracking catalyst for catalytic cracking reaction, and conduct catalyst regeneration cycle; Step (2): After the products of the first riser reactor are preliminarily separated by a pre-fractionating tower, the gas products enter an ethylene and propylene separation unit to separate ethylene and propylene, and the light oil in the liquid products enters a second riser reactor to contact with a second catalytic cracking catalyst for deep catalytic cracking reaction, and conduct catalyst regeneration cycle; Step (3): After the products of the second riser reactor are separated by a main fractionating tower, the gas products enter an ethylene and propylene separation unit to separate ethylene and propylene, and the heavy oil fraction in the liquid products enters an aromatics extraction unit to extract benzene, toluene and xylene therein.

2. The method according to claim 1, characterized in that, the method further includes: first desalt the crude oil electrically, then preheat the electrically desalted crude oil to 220 - 280 °C, and then feed it into the first riser reactor.

3. The method according to claim 1 or 2, characterized in that, the method further includes: return the gasoline fraction and diesel fraction in the liquid products obtained after separation by the main fractionating tower to the second riser reactor and contact with the light oil together with the second catalytic cracking catalyst for deep catalytic cracking reaction.

4. The method according to claim 3, characterized in that, the cut range of the gasoline fraction is initial boiling point - 200 °C, and the cut range of the diesel fraction is 200 - 350 °C.

5. The method according to claim 1, characterized in that, the method further includes: return the slurry obtained after preliminary separation by the pre-fractionating tower and / or the slurry obtained after separation by the main fractionating tower to the first riser reactor and contact with the crude oil together with the first catalytic cracking catalyst for catalytic cracking reaction.

6. The method according to claim 1 or 5, characterized in that, the method further includes: return the raffinate oil of the aromatics extraction unit to the first riser reactor and contact with the crude oil or a mixture of the crude oil and the slurry together with the first catalytic cracking catalyst for catalytic cracking reaction.

7. The method according to claim 1 or 2, characterized in that, the crude oil includes at least one of paraffinic crude oil, intermediate crude oil, naphthenic crude oil, wax oil and atmospheric residue, and a mixed oil obtained by blending at least one of hydrocracking tail oil, coal pyrolysis oil, shale oil and vacuum gas oil into the above at least one crude oil.

8. The method according to claim 1, characterized in that, in step (1), the reaction temperature of the catalytic cracking reaction is 550 - 600 °C, the catalyst-to-oil weight ratio is 4 - 20:1, and the temperature of catalyst regeneration is 650 - 750 °C; Preferably, the feed rates of the first riser reactor and the second riser reactor are 0.3 - 3 kg / h respectively, and the catalyst inventories are 8 - 10 kg respectively.

9. The method according to claim 1 or 8, characterized in that, The first catalytic cracking catalyst comprises a matrix and a catalytically active component. Based on 100% of the total weight of the first catalytic cracking catalyst, the content of the catalytically active component is 15-35%, and the balance is the matrix; The catalytically active component comprises a mixture of ZSM-5 and USY.

10. According to the method described in claim 1, characterized in that, in step (2), the reaction temperature of the deep catalytic cracking reaction is 580-650 °C, the weight ratio of catalyst to oil is 8-30:1, and the temperature of catalyst regeneration is 680-780 °C.

11. According to the method described in claim 1 or 10, characterized in that, The second catalytic cracking catalyst comprises a matrix and a catalytically active component. Based on 100% of the total weight of the second catalytic cracking catalyst, the content of the catalytically active component is 20-40%, and the balance is the matrix; The catalytically active component comprises a mixture of USY and rare earth metal-modified ZSM-5.

12. According to the method described in claim 11, characterized in that, The rare earth metal comprises at least one of scandium, yttrium, lanthanum and cerium.

13. A system for directly catalytically cracking crude oil to produce multiple chemicals for implementing the method for directly catalytically cracking crude oil to produce multiple chemicals according to any one of claims 1-12, characterized in that, The system comprises: A first riser reactor-regenerator, a pre-fractionating tower, a second riser reactor-regenerator, a main fractionating tower, an aromatics extraction unit, and an ethylene and propylene separation unit; wherein, the first riser reactor-regenerator comprises a first riser reactor and a first regenerator, the second riser reactor-regenerator comprises a second riser reactor and a second regenerator, and the ethylene and propylene separation unit comprises a propylene separation device and an ethylene separation device connected in sequence; The outlet of the first riser reactor-regenerator is connected to the inlet of the pre-fractionating tower through a pipeline, the gas outlet of the pre-fractionating tower is connected to the inlet of the propylene separation device through a pipeline, the light oil outlet of the pre-fractionating tower is connected to the inlet of the second riser reactor-regenerator through a pipeline, the outlet of the second riser reactor-regenerator is connected to the inlet of the main fractionating tower through a pipeline, the heavy oil fraction outlet of the main fractionating tower is connected to the inlet of the aromatics extraction unit through a pipeline, and the gas outlet of the main fractionating tower is connected to the inlet of the propylene separation device through a pipeline.

14. According to the system described in claim 13, characterized in that, The gasoline fraction and diesel fraction outlets of the main fractionating tower are connected to the inlet of the second riser reactor-regenerator through a pipeline.

15. According to the system described in claim 13 or 14, characterized in that, The slurry outlet of the pre-fractionating tower and / or the slurry outlet of the main fractionating tower are connected to the inlet of the first riser reactor-regenerator through a pipeline; Preferably, the outlet of the raffinate oil of the aromatics extraction unit is connected to the inlet of the first riser reactor-regenerator through a pipeline.

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