A method, system for catalytic cracking to produce light olefins and light aromatics

Abstract

The present application relates to a kind of catalytic cracking production low carbon olefin and light aromatic hydrocarbon method, system, the method includes: (1) make raw oil and catalytic cracking catalyst contact reaction in isokinetic fluidized bed reactor and obtain oil agent mixture;(2) make oil agent mixture carry out separation, obtain reaction oil gas and spent catalyst;(3) make reaction oil gas carry out separation, obtain low carbon olefin component, gasoline component and oil slurry component.The present application in isokinetic fluidized bed reactor, diesel oil and other light petroleum hydrocarbon with high silicon aluminum ratio catalytic cracking catalyst contact, through regeneration flue gas circulation maintains self-heating balance production low carbon olefin and light aromatic hydrocarbon etc..The method of the present application can process diesel oil and other light hydrocarbon while also processing naphtha and wax oil, residual oil and other heavy oil, diesel oil conversion rate is high, and can realize self-heating balance, not only solve the problem of refinery diesel oil production overcapacity, and also improve the crude oil processing benefit.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of catalytic cracking of hydrocarbons, and in particular to a method and system for catalytic cracking to produce low-carbon olefins and light aromatic hydrocarbons. BACKGROUND

[0002] In recent years, the consumption ratio of diesel to gasoline in the product oil market has been continuously decreasing, and diesel consumption has been zero growth or negative growth since it peaked at 176 Mt in 2014. According to statistics, a heavy-duty diesel vehicle emits about 150 times as much as a light-duty gasoline vehicle of the same stage per unit of mileage, and about 750 times as much as a light-duty gasoline vehicle of the same stage per year. This pollution situation further restricts the development of diesel vehicles. It is predicted that by 2025, diesel consumption will decrease to 168 Mt, and the consumption ratio of diesel to gasoline will decrease from the current 1.4 to less than 1. This will mean that there will be more than 10 million tons of excess diesel product, and the high particulate matter emission of diesel engines will further restrict the use of diesel, with more than a million tons of excess diesel for vehicles in a thousand-ton refinery. Reducing the diesel to gasoline ratio of refinery products and finding a way out for diesel have become urgent problems to be solved. Straight-run diesel accounts for about 50% of the total diesel, and reducing the production of straight-run diesel or converting it into other high-value-added products to adapt to the changing demand for diesel in the future is of great significance to ensure the balance between supply and demand in the product oil market.

[0003] For the conversion of straight-run diesel, light diesel can be blended into ethylene cracking feedstock at 10% or less, but compared with other light feedstocks, the yield of straight-run diesel steam cracking olefins is lower, and the decoking period is short; in addition, straight-run diesel can be processed by hydrocracking, with hydrogen consumption of 2.5%, naphtha yield of 50%-60%, and liquefied gas yield of 4%-5%. In recent years, domestic refineries have also used conventional catalytic cracking units to blend straight-run diesel to reduce the diesel to gasoline ratio, such as the conventional catalytic cracking unit of Sinopec Hainan Refining and Chemical Co., Ltd. blending straight-run diesel from the third line, with a gasoline yield of 41%, but the volume fraction of propylene in liquefied gas decreases by 0.52 percentage points, and the volume fraction of isobutene decreases by 0.12 percentage points, which is not conducive to the production of low-carbon olefins.

[0004] Straight-run diesel catalytic cracking or catalytic cracking technology has been slow, on the one hand, straight-run diesel has been valued as a high-cetane number vehicle fuel, and its use is large, but its resources are scarce, on the other hand, the yield of straight-run diesel catalytic cracking to produce gasoline or ethylene, propylene and other chemical materials is low; in addition, the straight-run diesel catalytic cracking produces less coke, which is not enough to maintain the self-heating balance of the conventional fluidized bed catalytic cracking, and catalytic cracking also requires a higher temperature.

[0005] The existing researches at home and abroad mainly focus on improving the conversion rate and solving the heat balance. For example, the patent CN111607425A discloses a straight-run diesel cracking method, that is, the straight-run diesel oil from which basic nitrogen is removed by phosphoric bishydronium salt and inert gases such as nitrogen are introduced into a fixed bed or moving bed reactor provided with activated pretreated ZSM-5 type nanomolecular sieve for catalytic cracking. The patent CN111718751A discloses a preparation method of the ZSM-5 type nanomolecular sieve catalyst modified by transition metal. As described in the two patents, the straight-run diesel oil is heated to a reaction temperature of 600 DEG C in the fixed bed reactor, and the diesel oil conversion rate is as high as 80.16%, and the low-carbon olefin yield is 34.13%. However, the single-pass cycle is as short as 47 hours, and the reaction cycle is short, so the reactor needs to be frequently switched. The single-pass cycle is extended to 78 hours by using the moving bed reactor, but the operation is difficult.

[0006] The patents CN104418685B and CN104418686A both disclose a catalytic cracking method of straight-run diesel oil in a riser reactor by using methane as a diluent and heat exchange between spent catalyst and flue gas. The patent CN104418686A further discloses a cracking gasoline aromatic extraction and C2-C4 alkane steam cracking technology. As described in the two patents, the mature fluidized bed technology is used to realize continuous reaction-regeneration, and the heat exchange between the spent catalyst and the flue gas is used to solve the heat balance problem. At a reaction temperature of 630 DEG C and a catalyst / oil mass ratio of 18, the diesel oil conversion rate is as high as 83.83% by carbon four recycling, and the ethylene and propylene yields are 16.52% and 35.19%, respectively. However, the heat exchanger needs to be additionally arranged for heat exchange between the spent catalyst and the flue gas, the process is complex, the equipment investment is high, the heat exchange efficiency is low, and the flue gas contains a certain amount of oxygen, so the spent catalyst is not fully combusted, and hidden dangers such as tail combustion are prone to occur.

[0007] Therefore, how to make the light oil better perform catalytic cracking to reduce the dry gas and coke yields and improve the yield of high-value products such as low-carbon olefins and light aromatics is a technical problem to be solved at present. SUMMARY

[0008] The present application provides a method and system for catalytic cracking to produce low-carbon olefins and light aromatics, which aims to make the diesel oil better perform catalytic cracking to obtain high-value products such as low-carbon olefins and light aromatics at a high yield.

[0009] In a first aspect, the present application relates to a method for catalytic cracking to produce low-carbon olefins and light aromatics, which comprises the following steps:

[0010] (1) contacting and reacting a raw oil with a catalytic cracking catalyst in an isokinetic fluidized bed reactor to obtain an oil-catalyst mixture;

[0011] (2) separating the oil mixture to obtain a reaction oil gas and a spent catalyst;

[0012] (3) separating the reaction oil gas to obtain a low carbon olefin component, a gasoline component and an oil slurry component;

[0013] (4) performing aromatic extraction on the gasoline component to obtain a light aromatic component and a raffinate oil component;

[0014] (5) regenerating the spent catalyst in a regenerator to obtain a regenerated catalyst and a flue gas; and recycling at least part of the regenerated catalyst to the isokinetic fluidized bed reactor and recycling at least part of the flue gas to the regenerator;

[0015] The isokinetic fluidized bed reactor is provided with a variable-diameter reaction section, and the inner diameter of the variable-diameter reaction section gradually increases from bottom to top.

[0016] The catalytic cracking catalyst comprises a zeolite, and the zeolite comprises a mesoporous zeolite with a ten-membered ring structure and an average pore size of 0.5-0.6 nm, and the mass fraction of the mesoporous zeolite in the catalytic cracking catalyst is 10-20%.

[0017] Optionally, the raw oil is diesel oil, and the diesel oil is fed into the isokinetic fluidized bed reactor from the lower part of the variable-diameter reaction section.

[0018] Preferably, at least part of the oil slurry component is fed into the isokinetic fluidized bed reactor from the middle part of the variable-diameter reaction section.

[0019] Optionally, the raw oil is diesel oil, and the diesel oil is fed into the isokinetic fluidized bed reactor from the lower part of the variable-diameter reaction section.

[0020] And, step (1) further comprises:

[0021] contacting the heavy oil with the catalytic cracking catalyst in a riser reactor;

[0022] In step (2), part of the oil mixture is derived from the contacting reaction of the diesel oil and the catalytic cracking catalyst, and the other part is derived from the contacting reaction of the heavy oil and the catalytic cracking catalyst; in step (5), part of the regenerated catalyst is recycled to the isokinetic fluidized bed reactor, and the other part of the regenerated catalyst is recycled to the riser reactor;

[0023] Preferably, at least part of the oil slurry component and / or at least part of the raffinate oil component are fed into the riser reactor; wherein the feeding position of the raffinate oil component is below the feeding position of the heavy oil, and the oil slurry component is fed into the riser reactor through the feeding position of the heavy oil.

[0024] Optionally, the raw oil comprises diesel oil and heavy oil, the diesel oil is fed into the isokinetic fluidized bed reactor by the lower part of the variable-diameter reaction section, and the heavy oil is fed into the isokinetic fluidized bed reactor by the middle part of the variable-diameter reaction section.

[0025] Preferably, at least part of the oil slurry component and / or at least part of the raffinate oil component are fed into the variable-diameter reaction section of the isokinetic fluidized bed reactor; wherein the feeding position of the raffinate oil component is below the feeding position of the diesel oil, and the oil slurry component is fed by the feeding position of the heavy oil.

[0026] Optionally, the diesel oil is selected from the group consisting of one or more of straight-run diesel oil, catalytically cracked diesel oil and hydrodiesel oil; and / or,

[0027] The diesel oil has a boiling point of 180-380℃ and a density less than or equal to 880 kg / m 3 .

[0028] Optionally, the heavy oil is wax oil and / or residual oil.

[0029] Optionally, the catalytic cracking catalyst further comprises a large-pore zeolite, an inorganic oxide, a clay and a modified oxide.

[0030] The molar ratio of SiO2 and Al2O3 in the mesoporous zeolite and the large-pore zeolite is greater than 10;

[0031] The mass fraction of the large-pore zeolite in the catalytic cracking catalyst is 20-40%;

[0032] The inorganic oxide comprises alumina and / or silicon oxide;

[0033] The mass fraction of the modified oxide in the catalytic cracking catalyst is 1.0-5.0%;

[0034] The modified oxide is selected from the group consisting of one or more metal element oxides and / or non-metal element oxides of Group IA, Group IIA, Group VA, Group VIA, Group VIIA, Group IB, Group IIB, Group IIIB and Group VIII;

[0035] The average particle size of the catalytic cracking catalyst is 40-150 microns.

[0036] Optionally, in step (1), the conditions under which the diesel oil is contacted with the catalytic cracking catalyst in the isokinetic fluidized bed reactor include:

[0037] the reaction temperature is 540-600℃, the reaction pressure is 0.2-0.5 MPa, the reaction time is 3.0-8.0 seconds, and the weight ratio of the catalytic cracking catalyst to the diesel oil is (5-10):1;

[0038] the diesel oil is fed into the isokinetic fluidized bed reactor under fluidization of a fluidizing medium;

[0039] the fluidizing medium is atomized water, and the mass ratio of the atomized water to the diesel oil is (0.10-0.20):1;

[0040] the oil-gas linear velocity in the variable-diameter reaction section is 1.0-2.0 m / s.

[0041] Optionally, the conditions under which the heavy oil is contacted with the catalytic cracking catalyst in the riser reactor include:

[0042] the reaction temperature is 540-600℃, the reaction pressure is 0.2-0.5 MPa, the reaction time is 3.0-8.0 seconds, and the weight ratio of the catalytic cracking catalyst to the heavy oil is (5-10):1;

[0043] the heavy oil is fed into the riser reactor under fluidization of a fluidizing medium;

[0044] the fluidizing medium is atomized water, and the mass ratio of the atomized water to the heavy oil is (0.10-0.20):1;

[0045] the oil-gas linear velocity in the riser reactor is 2.0-12.0 m / s.

[0046] Optionally, the method further comprises the following step before step (1):

[0047] preheating the raw oil to a preheating temperature, the preheating temperature being 200-400℃, preferably 220-320℃;

[0048] the preheating is performed by heating with a heating furnace, or by heat exchange between the raw oil and the product from step (3) and / or step (4); and / or,

[0049] in step (2), separating the oil-agent mixture includes the following steps:

[0050] separating the oil-agent mixture by cyclone separation to obtain a first reaction oil gas and a spent catalyst containing oil gas; then, stripping the spent catalyst containing oil gas to obtain the spent catalyst and a second reaction oil gas;

[0051] The reaction oil gas comprises the first reaction oil gas and the second reaction oil gas; and / or,

[0052] The separation in step (3) further obtains gaseous alkanes and cycle oil.

[0053] Optionally, in step (5):

[0054] The circulation rate of the regenerated catalyst is 150-200 kg / (m 2 ·s);

[0055] The regeneration atmosphere in the regenerator is selected from the group consisting of one or more of air, oxygen-enriched air and pure oxygen;

[0056] The regeneration temperature in the regenerator is 600-700℃, and the pressure is 0.3-0.6 MPa;

[0057] The flue gas is optionally recycled to the regenerator after heat exchange, and the temperature of the flue gas recycled to the regenerator is 300-600℃.

[0058] In a second aspect, the present application relates to a system for catalytically cracking to produce low-carbon olefins and light aromatic hydrocarbons, which comprises an isokinetic fluidized bed reactor, a cyclone separator, a settler, an oil gas separation system, an aromatic hydrocarbon extraction system and a regenerator;

[0059] The isokinetic fluidized bed reactor is provided with a reactor pre-lifting section, a reactor reaction section, a reactor outlet section and a catalyst stripping section;

[0060] The reactor reaction section is connected between the outlet of the reactor pre-lifting section and the inlet of the reactor outlet section;

[0061] The reactor reaction section is a variable-diameter reaction section, and the inner diameter of the reactor reaction section gradually increases from bottom to top; the lower part of the reactor reaction section is provided with a light hydrocarbon raw oil inlet and a first atomized steam inlet, and the first atomized steam inlet is in communication with the light hydrocarbon raw oil inlet;

[0062] The oil agent outlet of the reactor outlet section is in communication with the oil agent inlet of the cyclone separator, the catalyst outlet of the cyclone separator is in communication with the inlet of the settler, and the oil gas outlet of the cyclone separator is in communication with the oil gas inlet of the oil gas separation system;

[0063] The outlet of the settler is in communication with the catalyst inlet of the catalyst stripping section, the catalyst outlet of the catalyst stripping section is in communication with the spent catalyst inlet of the regenerator, and the oil gas outlet of the catalyst stripping section is in communication with the oil gas inlet of the oil gas separation system;

[0064] The regenerator is provided with an oxygen-containing regeneration gas inlet and a flue gas outlet, the flue gas outlet is communicated with the oxygen-containing regeneration gas inlet through a flue gas circulation pipeline, a regenerated catalyst outlet of the regenerator is communicated with a catalyst inlet of the reactor pre-lifting section through a first regenerated catalyst conveying pipeline, and a bottom of the reactor pre-lifting section is provided with a first fluidizing medium inlet;

[0065] The oil-gas separation system is provided with a low-carbon olefin outlet, a gaseous alkane outlet, a gasoline outlet, a circulating oil outlet and an oil slurry outlet; the gasoline outlet is communicated with an inlet of the aromatic extraction system, and the aromatic extraction system is provided with a light aromatic outlet and a raffinate outlet;

[0066] Preferably, an oil-gas outlet of the cyclone separator is communicated with an oil-gas inlet of the oil-gas separation system through a reaction oil-gas pipeline, and an oil-gas outlet of the catalyst stripping section is communicated with the oil-gas inlet of the oil-gas separation system through the reaction oil-gas pipeline;

[0067] Preferably, a lower part of the catalyst stripping section is provided with a stripping medium inlet;

[0068] Preferably, a catalyst outlet of the catalyst stripping section is communicated with a spent catalyst inlet of the regenerator through a spent catalyst conveying pipeline;

[0069] Preferably, a middle part of the reactor reaction section is provided with a first heavy feed oil inlet and a second atomizing steam inlet, and the first heavy feed oil inlet is communicated with the second atomizing steam inlet;

[0070] Preferably, the oil slurry outlet is communicated with the first heavy feed oil inlet, and / or the reactor reaction section is provided with a raffinate back-refining inlet communicated with the raffinate outlet, and the raffinate back-refining inlet is located below the light hydrocarbon feed oil inlet.

[0071] Optionally, the system is further provided with a riser reactor, and the riser reactor is provided with a second heavy feed oil inlet and a third atomizing steam inlet, and the second heavy feed oil inlet is communicated with the third atomizing steam inlet;

[0072] A regenerated catalyst outlet of the regenerator is communicated with a catalyst inlet of a bottom of the riser reactor through a second regenerated catalyst conveying pipeline, and the bottom of the riser reactor is further provided with a second fluidizing medium inlet;

[0073] An oil catalyst outlet of the riser reactor is communicated with an oil catalyst inlet of the cyclone separator;

[0074] Preferably, the oil slurry outlet is in communication with the second heavy feed oil inlet, and / or the riser reactor is provided with a raffinate oil inlet in communication with the raffinate oil outlet, which is located below the second heavy feed oil inlet.

[0075] Advantages:

[0076] The present application enables diesel to be contacted with a high-silicon-to-aluminum ratio catalytic cracking catalyst in a variable-diameter reaction section of an isokinetic fluidized bed reactor for reaction, which can reduce the dry gas and coke yield of diesel under high reaction severity, and significantly increase the yield of low-carbon olefins and light aromatic hydrocarbons; the high-temperature flue gas after regeneration is all returned to the regenerator for recycling, achieving self-heat balance of the diesel catalytic cracking reaction regeneration, and enabling high-efficiency continuous production. BRIEF DESCRIPTION OF DRAWINGS

[0077] Figure 1 is a structural schematic diagram of one specific embodiment of a system for catalytically cracking to produce low-carbon olefins and light aromatic hydrocarbons according to the present application;

[0078] Figure 2 is a structural schematic diagram of another specific embodiment of a system for catalytically cracking to produce low-carbon olefins and light aromatic hydrocarbons according to the present application;

[0079] REFERENCE SIGNS

[0080] 1 isokinetic fluidized bed reactor, 2 light hydrocarbon feed oil inlet, 3 first atomizing steam inlet,

[0081] 4 first fluidizing medium inlet, 5 reaction oil gas pipeline, 6 oil gas separation system,

[0082] 7 low-carbon olefin outlet, 8 gaseous alkane outlet, 9 gasoline outlet,

[0083] 10 circulating oil outlet, 11 oil slurry outlet, 12 first heavy feed oil inlet,

[0084] 13 second atomizing steam inlet, 14 stripping medium inlet, 15 spent catalyst conveying pipeline,

[0085] 16 regenerator, 17 oxygen-containing regeneration gas inlet, 18 first regenerated catalyst conveying pipeline,

[0086] 19 flue gas outlet, 20 flue gas circulation pipeline, 21 riser reactor,

[0087] 22 second fluidizing medium inlet, 23 second regenerated catalyst conveying pipeline, 24 aromatic hydrocarbon extraction system,

[0088] 25 light aromatic hydrocarbon outlet, 26 raffinate oil outlet, 27 second heavy feed oil inlet,

[0089] 28 third mist vapor inlet

[0090] I reactor pre-lift section, II reactor reaction section, III reactor outlet section,

[0091] IV settler, IV-1 cyclone separator, IV-2 catalyst stripping section. DETAILED DESCRIPTION

[0092] The application will be further described in details by the accompanying drawings and examples. The features and advantages of the application will become more apparent through these descriptions.

[0093] The word "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any implementation described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other implementations. The

[0094] Furthermore, the technical features involved in the different embodiments of the application described below can be combined with each other as long as there is no conflict.

[0095] In a first aspect, the application relates to a method for producing low-carbon olefins and light aromatics by catalytic cracking, which comprises the following steps:

[0096] (1) contacting and reacting a raw oil with a catalytic cracking catalyst in an isokinetic fluidized bed reactor to obtain an oil-agent mixture;

[0097] (2) separating the oil-agent mixture to obtain a reaction oil gas and a spent catalyst;

[0098] (3) separating the reaction oil gas to obtain a low-carbon olefin component, a gasoline component, and an oil slurry component;

[0099] (4) performing aromatics extraction on the gasoline component to obtain a light aromatic component and a raffinate oil component;

[0100] (5) regenerating the spent catalyst in a regenerator to obtain a regenerated catalyst and flue gas; and returning at least part of the regenerated catalyst to the isokinetic fluidized bed reactor for recycling, and returning at least part of the flue gas to the regenerator for recycling;

[0101] wherein the isokinetic fluidized bed reactor is provided with a variable-diameter reaction section, and the inner diameter of the variable-diameter reaction section gradually increases from bottom to top;

[0102] The catalytic cracking catalyst comprises a zeolite, the zeolite comprises a mesoporous zeolite with a ten-membered ring structure and an average pore size of 0.5-0.6 nm, and the mass fraction of the mesoporous zeolite in the catalytic cracking catalyst is 10-20%.

[0103] It should be noted that the method of the present application is based on a catalytic cracking catalyst comprising 10-20% of a mesoporous zeolite with a ten-membered ring structure and an average pore size of 0.5-0.6 nm, and the contacting and reaction are carried out in an isokinetic fluidized bed reactor, especially the inner diameter of the isokinetic fluidized bed reactor gradually increases from bottom to top, which is beneficial to the production of low-carbon olefins, light aromatics and other products from the raw oil. And the flue gas obtained after regeneration in the regenerator is recycled to the regenerator, which can maintain the self-heating balance, achieve natural balance, and is also beneficial to the production of low-carbon olefins, light aromatics and other products, and can improve the processing benefit of crude oil.

[0104] According to the first specific embodiment of the method according to the first aspect of the present application, the raw oil is diesel oil, and the diesel oil is fed into the isokinetic fluidized bed reactor from the lower part of the variable-diameter reaction section.

[0105] Preferably, at least part of the oil slurry component is fed into the isokinetic fluidized bed reactor from the middle part of the variable-diameter reaction section.

[0106] It should be noted that the isokinetic fluidized bed reactor does not require external heating and can produce continuously, and compared with the conventional riser reactor, the oil agent is more fully contacted, and when used for catalytic cracking of light hydrocarbons such as diesel oil for volume expansion, higher low-carbon olefin yield and light aromatics yield can be obtained.

[0107] Especially, as a preferred embodiment, the diesel oil is fed into the isokinetic fluidized bed reactor from the lower part of the variable-diameter reaction section, and at least part of the oil slurry component is fed into the isokinetic fluidized bed reactor from the middle part of the variable-diameter reaction section for back refining, thereby being able to obtain low-carbon olefins, light aromatics and the like with higher yield.

[0108] According to the second specific embodiment of the method according to the first aspect of the present application, the raw oil is diesel oil, and the diesel oil is fed into the isokinetic fluidized bed reactor from the lower part of the variable-diameter reaction section.

[0109] And, step (1) further comprises:

[0110] contacting and reacting the heavy oil with the catalytic cracking catalyst in the riser reactor;

[0111] In step (2), part of the oil agent mixture is derived from the contacting reaction of the diesel oil and the catalytic cracking catalyst, and part of the oil agent mixture is derived from the contacting reaction of the heavy oil and the catalytic cracking catalyst; in step (5), part of the regenerated catalyst is recycled to the isokinetic fluidized bed reactor, and part of the regenerated catalyst is recycled to the riser reactor;

[0112] Preferably, at least part of the slurry oil component and / or at least part of the raffinate oil component is fed into the riser reactor; wherein the feeding position of the raffinate oil component is below the feeding position of the heavy oil, and the slurry oil component is fed into the riser reactor through the feeding position of the heavy oil.

[0113] It should be noted that the process method of the embodiment is a process method of coupling catalytic cracking of the isokinetic fluidized bed reactor and the riser reactor. In the method of the embodiment, the light hydrocarbon such as diesel oil can be processed at the same time as the heavy oil such as naphtha and wax oil, and residual oil. The diesel oil conversion rate is high, which not only solves the problem of excess production capacity of the refinery diesel oil, but also improves the crude oil processing benefit.

[0114] In addition, as a preferred embodiment, the diesel oil is fed into the isokinetic fluidized bed reactor from the lower part of the variable-diameter reaction section. When the slurry oil component and the raffinate oil component are backfired, the slurry oil component is fed into the riser reactor through the feeding position of the heavy oil, and the feeding position of the raffinate oil component is below the feeding position of the heavy oil. This is conducive to obtaining higher low-carbon olefin yield and light aromatic yield, and better catalytic cracking of diesel oil and heavy oil.

[0115] According to a third specific embodiment of the method of the first aspect of the present application, the raw material oil includes diesel oil and heavy oil, the diesel oil is fed into the isokinetic fluidized bed reactor from the lower part of the variable-diameter reaction section, and the heavy oil is fed into the isokinetic fluidized bed reactor from the middle part of the variable-diameter reaction section.

[0116] Preferably, at least part of the slurry oil component and / or at least part of the raffinate oil component is fed into the variable-diameter reaction section of the isokinetic fluidized bed reactor; wherein the feeding position of the raffinate oil component is below the feeding position of the diesel oil, and the slurry oil component is fed from the feeding position of the heavy oil.

[0117] It should be noted that, as described above, the method of the embodiment can also process light hydrocarbons such as diesel oil and heavy oils such as wax oil and residual oil at the same time. The embodiment can better convert diesel oil and heavy oil, and can better produce low-carbon olefins and light aromatics and other products. In particular, as described above, the feeding positions of the diesel oil and the heavy oil are controlled, and the slurry oil component and the raffinate oil component are fed at the positions when backfired, which is conducive to better catalytic cracking of diesel oil and heavy oil into low-carbon olefins and light aromatics and other high-value products.

[0118] According to one specific embodiment of the method of the first aspect of the present application, the diesel oil is selected from a combination of one or more of straight-run diesel oil, catalytically cracked diesel oil, and hydrogenated diesel oil; and / or,

[0119] The diesel has a boiling point of 180-380 DEG C and a density less than or equal to 880 kg / m 3 .

[0120] It should be noted that the method of the present application has wide applicability, and in addition to the diesel described above, it can also be applied to catalytic cracking of other light hydrocarbon oils, and the present application is not limited. Catalytic cracking of the diesel described above as raw oil in the isokinetic fluidized bed reactor can solve the problem of diesel surplus, and can convert the diesel into gasoline and liquefied gas and other products.

[0121] According to a specific embodiment of the method according to the first aspect of the present application, the heavy oil is wax oil and / or residual oil.

[0122] It should be noted that the method of the present application has wide applicability, and in addition to the wax oil and residual oil described above, it can also be applied to catalytic cracking of other heavy oils. Catalytic cracking of the wax oil and / or residual oil as heavy oil in the isokinetic fluidized bed reactor together with the diesel, or catalytic cracking of the diesel and the heavy oil in the isokinetic fluidized bed reactor and the riser reactor, respectively, especially according to the feeding position in the specific embodiment described above, the heavy oil and the diesel can be better converted into low-carbon olefins and light aromatic hydrocarbons and other high-value products by catalytic cracking.

[0123] According to a specific embodiment of the method according to the first aspect of the present application, the catalytic cracking catalyst further comprises a large-pore zeolite, an inorganic oxide, a clay, and a modified oxide;

[0124] The molar ratio of SiO2 and Al2O3 in the mesoporous zeolite and the macroporous zeolite is greater than 10;

[0125] The mass fraction of the macroporous zeolite in the catalytic cracking catalyst is 20-40%;

[0126] The inorganic oxide comprises alumina and / or silicon oxide;

[0127] The mass fraction of the modified oxide in the catalytic cracking catalyst is 1.0-5.0%;

[0128] The modified oxide is selected from one or more metal element oxides and / or non-metal element oxides in Group IA, Group IIA, Group VA, Group VIA, Group VIIA, Group IB, Group IIB, Group IIIB, and Group VIII;

[0129] The average particle size of the catalytic cracking catalyst is 40-150 microns.

[0130] It should be noted that in the method for producing low-carbon olefins and light aromatic hydrocarbons by catalytic cracking according to the present application, the catalyst used is a high-silica catalyst for catalytic cracking, which contains both mesoporous zeolite and macroporous zeolite, and the molar ratio of SiO2 to Al2O3 in each zeolite is greater than 10, specifically, the molar ratio of SiO2 to Al2O3, i.e., the silica-alumina ratio, can be or greater than 15, 20, 25, 30, or 35, etc.

[0131] The mass content of inorganic oxides and clay in the catalytic cracking catalyst can be 15-34% and 20-35%, respectively; the macroporous zeolite can be selected from one or more of REY zeolite, HY zeolite, REHY zeolite, ultra-stable Y zeolite (USY zeolite), high-silica Y zeolite, and beta zeolite, preferably high-silica ultra-stable Y zeolite with a total silica-alumina ratio (molar ratio of SiO2 to Al2O3) higher than 10. The mesoporous zeolite is selected from one or more of ZSM-5 zeolite, ZSM-11 zeolite, ZSM-12 zeolite, ZSM-23 zeolite, ZSM-35 zeolite, ZSM-38 zeolite, ZSM-48 zeolite, and ZRP-1 zeolite. The inorganic oxide is silicon oxide and / or aluminum oxide; the clay is selected from one or more of silicon dioxide, kaolin, halloysite, montmorillonite, diatomite, halloysite, saponite, rectorite, sepiolite, attapulgite, hydrotalcite, and bentonite. The modified oxide composed of metal oxides and / or non-metal oxides can be selected from oxides of one or more elements from Group IA, Group IIA, Group VA, Group VIA, Group VIIA, Group IB, Group IIB, Group IIIB, and Group VIII, and can be oxides of transition metal elements or non-transition metal elements.

[0132] It should be noted that in the method according to the present application, diesel, or diesel and heavy oil, is contacted with the catalytic cracking catalyst described above in the isokinetic fluidized bed reactor, or in the isokinetic fluidized bed reactor and the riser reactor, to further improve the conversion rate of the raw oil and better prepare high-value products.

[0133] According to another specific embodiment of the method according to the first aspect of the present application, in step (1), the conditions for contacting the diesel with the catalytic cracking catalyst in the isokinetic fluidized bed reactor include:

[0134] The reaction temperature is 540-600°C, the reaction pressure is 0.2-0.5 MPa, the reaction time is 3.0-8.0 seconds, and the weight ratio of the catalytic cracking catalyst to the diesel is (5-10):1;

[0135] The diesel is fed into the isokinetic fluidized bed reactor under the fluidization of the fluidizing medium;

[0136] The fluidization medium is atomized water, and the mass ratio of the atomized water to the diesel oil is (0.10-0.20):1;

[0137] The oil-gas linear velocity of the diameter-variable reaction section is 1.0-2.0 m / s.

[0138] It should be noted that, in the method of the present application, the conditions for the contacting reaction of the heavy oil and the catalytic cracking catalyst in step (1) are controlled as described above, so that the diesel oil can be better converted into low-carbon olefins, light aromatics and the like under the catalysis of the catalytic cracking catalyst.

[0139] According to a specific embodiment of the method of the first aspect of the present application, the conditions for the contacting reaction of the heavy oil and the catalytic cracking catalyst in the riser reactor include:

[0140] The reaction temperature is 540-600℃, the reaction pressure is 0.2-0.5 MPa, the reaction time is 3.0-8.0 seconds, and the weight ratio of the catalytic cracking catalyst to the heavy oil is (5-10):1;

[0141] The heavy oil is fed into the riser reactor under the fluidization of a fluidization medium;

[0142] The fluidization medium is atomized water, and the mass ratio of the atomized water to the heavy oil is (0.10-0.20):1;

[0143] The oil-gas linear velocity of the riser reactor is 2.0-12.0 m / s.

[0144] It should be noted that, the conditions for the contacting reaction of the heavy oil and the catalytic cracking catalyst in the riser reactor are controlled as described above, so that the heavy oil can be better converted into low-carbon olefins, light aromatics and the like high-value products through catalytic cracking.

[0145] According to a specific embodiment of the method of the first aspect of the present application, the method further includes the following step before step (1):

[0146] The raw oil is preheated to a preheating temperature, and the preheating temperature is 200-400℃, preferably 220-320℃;

[0147] The preheating is performed by heating with a heating furnace, or the raw oil is heat-exchanged with the product obtained from step (3) and / or step (4); and / or,

[0148] In step (2), the separation of the oil-agent mixture includes the following steps:

[0149] The oil-agent mixture is separated by cyclone separation to obtain a first reaction oil gas and an oil-gas-containing spent catalyst; then, the oil-gas-containing spent catalyst is stripped to obtain the spent catalyst and a second reaction oil gas;

[0150] The reaction oil gas includes the first reaction oil gas and the second reaction oil gas; and / or,

[0151] The separation in step (3) further obtains gaseous alkanes and cycle oil.

[0152] It should be noted that the separation in step (3) obtains low-carbon olefins, gaseous alkanes, gasoline, cycle oil, oil slurry and the like, wherein the low-carbon olefins include ethylene, propylene, butene and the like; and then part or all of the gasoline obtained from step (3) is subjected to aromatic extraction in step (4) to obtain light aromatic components and raffinate components and the like, wherein the light aromatic components include benzene, toluene, ethylbenzene, xylene and the like.

[0153] According to a specific embodiment of the method according to the first aspect of the present application, in step (5):

[0154] The cycle rate of the regenerated catalyst is 150-200 kg / (m 2 ·s);

[0155] The regeneration atmosphere in the regenerator is selected from a combination of one or more of air, oxygen-enriched air and pure oxygen;

[0156] The regeneration temperature in the regenerator is 600-700℃, and the pressure is 0.3-0.6 MPa;

[0157] 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 300-600℃.

[0158] It should be noted that the high-temperature flue gas containing oxygen obtained by catalyst regeneration in the regenerator can be returned to the regenerator for recycling without heat exchange or after partial heat exchange, which can fully utilize the oxygen in the flue gas and maintain a relatively high regeneration temperature and a relatively high regeneration agent temperature in the regenerator. The regeneration atmosphere in the regenerator is preferably oxygen-enriched air and / or pure oxygen, which requires less heat for heating the regeneration gas, has high charring intensity and high regeneration temperature, and can maintain a relatively high regeneration agent temperature. The high-temperature flue gas after regeneration is partially and / or entirely returned to the regenerator, which not only fully utilizes the oxygen in the flue gas, but also solves the problem of heat carried out of the system by the flue gas and reduces the emission of waste gas such as carbon dioxide, thereby achieving significant energy saving and emission reduction.

[0159] In a second aspect, the present application relates to a system for producing low-carbon olefins and light aromatics by catalytic cracking, as shown in Figure 1 The system includes an isokinetic fluidized bed reactor 1, a cyclone separator IV-1, a settler IV, an oil gas separation system 6, an aromatic extraction system 24 and a regenerator 16.

[0160] The isokinetic 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;

[0161] The reactor reaction section II is connected between the outlet of the reactor pre-lifting section I and the inlet of the reactor outlet section III;

[0162] The reactor reaction section II is a variable-diameter reaction section, and the inner diameter of the reactor reaction section II gradually increases from bottom to top; the lower part of the reactor reaction section II is provided with a light hydrocarbon raw oil inlet 2 and a first atomizing steam inlet 3, and the first atomizing steam inlet 3 is in communication with the light hydrocarbon raw oil inlet 2;

[0163] The oil agent outlet of the reactor outlet section III is in communication with the oil agent inlet of the cyclone separator IV-1, the catalyst outlet of the cyclone separator IV-1 is in communication with the inlet of the settler IV, and the oil gas outlet of the cyclone separator IV-1 is in communication with the oil gas inlet of the oil gas separation system 6;

[0164] The outlet of the settler IV is in communication with the catalyst inlet of the catalyst stripping section IV-2, the catalyst outlet of the catalyst stripping section IV-2 is in communication with the spent catalyst inlet of the regenerator 16, and the oil gas outlet of the catalyst stripping section IV-2 is in communication with the oil gas inlet of the oil gas separation system 6;

[0165] The regenerator 16 is provided with an oxygen-containing regeneration gas inlet 17 and a flue gas outlet 19, the flue gas outlet 19 is in communication with the oxygen-containing regeneration gas inlet 17 through a flue gas circulation pipeline 20, the regenerated catalyst outlet of the regenerator 16 is in communication with the catalyst inlet of the reactor pre-lifting section I through a first regenerated catalyst conveying pipeline 18, and the bottom of the reactor pre-lifting section I is provided with a first fluidizing medium inlet 4;

[0166] The oil gas separation system 6 is provided with a low-carbon olefin outlet 7, a gaseous alkane outlet 8, a gasoline outlet 9, a circulating oil outlet 10 and an oil slurry outlet 11; the gasoline outlet 9 is in communication with the inlet of the aromatic hydrocarbon extraction system 24, and the aromatic hydrocarbon extraction system 24 is provided with a light aromatic hydrocarbon outlet 25 and a raffinate oil outlet 26;

[0167] Preferably, the oil gas outlet of the cyclone separator IV-1 is in communication with the oil gas inlet of the oil gas separation system 6 through a reaction oil gas pipeline 5, and the oil gas outlet of the catalyst stripping section IV-2 is in communication with the oil gas inlet of the oil gas separation system 6 through the reaction oil gas pipeline 5;

[0168] Preferably, the lower part of the catalyst stripping section IV-2 is provided with a stripping medium inlet 14;

[0169] Preferably, the catalyst outlet of the catalyst stripping section IV-2 is connected in communication with the spent catalyst inlet of the regenerator 16 through a spent catalyst delivery pipeline 15.

[0170] Preferably, the middle part of the reactor reaction section II is provided with a first heavy feed oil inlet 12 and a second atomized steam inlet 13, and the first heavy feed oil inlet 12 is connected in communication with the second atomized steam inlet 13.

[0171] Preferably, the oil slurry outlet 11 is connected in communication with the first heavy feed oil inlet 12, and / or the reactor reaction section II is provided with a raffinate oil back-refining inlet connected in communication with the raffinate oil outlet 26, which is located below the light hydrocarbon feed oil inlet 2.

[0172] The isokinetic fluidized bed reactor of the present application refers to the relative uniform linear velocity of the catalytic cracking reaction oil gas maintained in the fluidized bed reactor. Compared with the ordinary fluidized bed with uniform diameter, the oil gas in the isokinetic fluidized bed reactor contacts the catalyst in a uniform linear velocity and flat flow state, the catalyst has high density, and the oil gas contact is more sufficient.

[0173] It should be noted that the catalyst in the isokinetic fluidized bed reactor 1 can flow upwards or downwards; preferably, the catalyst flows upwards. The isokinetic fluidized bed reactor 1 and the regenerator 16 can be arranged in parallel or overlapped, and the isokinetic fluidized bed reactor 1 and the settler IV can be built-in or built-out; air and / or water vapor and other media are used to lift the catalyst to make it circulate between the reactor and the regenerator.

[0174] As a first specific embodiment, diesel is fed through the light hydrocarbon feed oil inlet 2 and enters the lower part of the reactor reaction section II under the atomization of the atomized steam entering through the first atomized steam inlet 3. As a second specific embodiment, diesel is fed through the light hydrocarbon feed oil inlet 2 and enters the lower part of the reactor reaction section under the atomization of the atomized steam entering through the first atomized steam inlet 3; heavy oil enters the middle part of the reactor reaction section II through the first heavy feed oil inlet 12.

[0175] In the two specific embodiments, the reacted oil agent mixture flows upwards to the reactor outlet section III, and then enters the cyclone separator IV-1 for cyclone separation. The separated reaction oil gas flows to the oil gas separation system 6 for oil gas separation, and the spent catalyst containing the reaction oil gas enters the settler IV for settlement and then enters the catalyst stripping section IV-2 for stripping. The obtained spent catalyst enters the regenerator 16 for regeneration, and the obtained reaction oil gas enters the oil gas separation system 6 for oil gas separation.

[0176] The oxygen-containing gas enters the regenerator 16 through the oxygen-containing regeneration gas inlet 17, and the spent catalyst is regenerated in the oxygen-containing atmosphere. The regenerated catalyst can be returned to the isokinetic fluidized bed reactor 1 through the first regenerated catalyst delivery pipeline 18 for recycling. The high-temperature flue gas flows out through the flue gas outlet 19 and can be partially or completely returned to the regenerator 16 through the flue gas circulation pipeline 20 for recycling.

[0177] As a preferred embodiment, the slurry flows out through the slurry outlet 11 and enters the reactor reaction section II through the first heavy oil inlet 12 for back-fining. The raffinate flows out through the raffinate outlet 26 and enters the reactor reaction section II through the raffinate back-fining inlet for back-fining.

[0178] According to another specific embodiment of the system according to the second aspect of the present application, as shown in Figure 2 The system is further provided with a riser reactor 21, which is provided with a second heavy oil inlet 27 and a third atomized steam inlet 28, and the second heavy oil inlet 27 is in communication with the third atomized steam inlet 28.

[0179] The regenerated catalyst outlet of the regenerator 16 is in communication with the catalyst inlet at the bottom of the riser reactor 21 through the second regenerated catalyst delivery pipeline 23, and the bottom of the riser reactor 21 is further provided with a second fluidizing medium inlet 22.

[0180] The oil product outlet of the riser reactor 21 is in communication with the oil product inlet of the cyclone separator IV-1.

[0181] Preferably, the slurry outlet 11 is in communication with the second heavy oil inlet 27, and / or the riser reactor 21 is provided with a raffinate inlet in communication with the raffinate outlet 26, which is located below the second heavy oil inlet 27.

[0182] It should be noted that in this embodiment, diesel is fed to the reactor reaction section II of the isokinetic fluidized bed reactor 1 through the light oil inlet 2, and heavy oil is fed to the riser reactor 21 through the second heavy oil inlet 27. Diesel and catalytic cracking catalyst are contacted and reacted in the isokinetic fluidized bed reactor 1, and heavy oil and catalytic cracking catalyst are contacted and reacted in the riser reactor 21. The oil product mixtures produced in the two reactors can be separated in one cyclone separator or can be separated in two cyclone separators respectively. In this embodiment, the two groups of oil product mixtures are separated in one cyclone separator, and the reaction oil gas and spent catalyst are separated through separation, sedimentation and extraction.

[0183] As a preferred embodiment, the slurry oil enters the riser reactor through the second heavy oil inlet 27 for back-fining, and the raffinate oil enters the riser reactor through the raffinate oil inlet for back-fining.

[0184] As shown in the embodiment, an upflowing variable-diameter isokinetic fluidized bed reactor 1 is used, the light hydrocarbon oil enters the reactor through the light hydrocarbon oil inlet 2 for catalytic cracking reaction with the regenerant, the spent catalyst is separated from the oil gas after reaction and then regenerated, and the flue gas after regeneration is partially recycled back to the regenerator. Figure 1

[0185] The light hydrocarbon oil fed through the light hydrocarbon oil inlet 2 is atomized by the atomizing steam fed through the first atomizing steam inlet 3 and enters the bottom or lower part of the reactor reaction section II of the isokinetic fluidized bed reactor 1, and the hot regenerant is introduced into the reactor pre-lifting section I of the isokinetic fluidized bed reactor 1 through the first regenerant conveying pipeline 18 and then upflows into the reactor reaction section II under the fluidization of the fluidizing medium fed through the first fluidizing medium inlet 4, and the light hydrocarbon oil contacts the hot regenerant for catalytic cracking reaction.

[0186] The oil gas and catalyst after reaction enter the cyclone separator IV-1 through the reactor outlet section III for oil catalyst separation, the separated catalyst is settled in the settler IV to the catalyst stripping section IV-2, and the spent catalyst is stripped by the stripping medium fed through the stripping medium inlet 14 and then enters the regenerator 16 through the spent catalyst conveying pipeline 15.

[0187] The spent catalyst is regenerated in the regenerator under an oxygen-containing atmosphere, the oxygen-containing regeneration gas fed through the oxygen-containing regeneration gas inlet 17 includes air, oxygen, etc., the regeneration temperature is 600-700℃, and the regenerated catalyst is recycled; and the flue gas after regeneration is partially recycled back to the regenerator through the flue gas recycling pipeline 20.

[0188] ​The separated reaction oil gas enters the oil gas separation system 6 through the reaction oil gas pipeline 5, and after oil gas separation, low carbon olefins are obtained at the low carbon olefin outlet 7, gaseous alkanes are obtained at the gaseous alkane outlet 8, gasoline is obtained at the gasoline outlet 9, cycle oil is obtained at the cycle oil outlet 10, and oil slurry is obtained at the oil slurry outlet 11; and the gasoline is further extracted by the aromatic extraction system 24, light aromatics are obtained at the light aromatic outlet 25, and raffinate is obtained at the raffinate outlet 26; wherein the cycle oil and the oil slurry and the raffinate can be selected to be recycled and / or not recycled according to production needs. In order to meet the needs of self-heating balance of the device, the oil slurry and / or the cycle oil are preferentially selected to be recycled; the oil slurry is recycled, and / or the heavy oil feedstock enters the reactor after being atomized by the atomizing steam 13 entering through the second atomizing steam inlet 13 and the first heavy oil feedstock inlet 12, and is preferentially introduced into the middle of the reaction section II of the reactor, i.e. the light hydrocarbon feedstock is fed at the upper part of the light hydrocarbon feedstock inlet 2. In order to meet the demand for producing chemical materials, the raffinate is preferentially selected to be recycled; the raffinate can be mixed with the light oil feedstock and then introduced into the reactor, and is preferentially introduced into the bottom of the reaction section II of the reactor, i.e. the light hydrocarbon feedstock can be fed at the lower part of the light hydrocarbon feedstock inlet 2.

[0189] Figure 2 The process flow diagram of another embodiment of the present disclosure is the same as that of Example 1, and the light hydrocarbon feedstock uses a variable-diameter isokinetic fluidized bed reactor 1, and the difference is that the oil slurry is recycled and / or the heavy oil feedstock enters the conventional riser reactor 21 through the second heavy oil feedstock inlet 27, and the conventional riser reactor 21 and the isokinetic fluidized bed reactor 1 can each use a separate settler or share one settler, and in this embodiment, both use one settler. The process flow is as follows:

[0190] The light hydrocarbon feedstock entering through the light hydrocarbon feedstock inlet 2 is atomized by the atomizing steam entering through the first atomizing steam inlet 3 and then enters the bottom or lower part of the reaction section II of the isokinetic fluidized bed reactor 1, and the hot regenerant is introduced into the reactor pre-lifting section I of the isokinetic fluidized bed reactor through the first regenerant conveying pipeline 18, and under the fluidization of the fluidizing medium entering through the first fluidizing medium inlet 4, it goes up to the reaction section II, and the light hydrocarbon feedstock contacts the hot regenerant to perform catalytic cracking reaction.

[0191] The heavy oil feedstock is fed through the second heavy oil feedstock inlet 27 and atomized by the atomizing steam entering through the third atomizing steam inlet 28, and then enters the lower part of the riser reactor 21, and the hot regenerant is introduced into the bottom of the riser reactor through the second regenerant conveying pipeline 23, and under the fluidization of the fluidizing medium fed through the second fluidizing medium inlet 22, it goes up, and the heavy oil feedstock contacts the hot regenerant to perform catalytic cracking reaction.

[0192] The oil agent after reaction of the light hydrocarbon raw material oil and the heavy raw material oil enters the cyclone separator IV-1 for oil agent separation; in the isokinetic fluidized bed reactor, the oil gas after reaction and the catalyst enter the cyclone separator IV-1 through the reactor outlet section III for oil agent separation, the separated catalyst is settled in the settler IV to the catalyst stripping section IV-2, after stripping by the stripping medium fed through the stripping medium inlet, the catalyst enters the regenerator 16 through the spent catalyst conveying pipeline 15; the spent catalyst is regenerated in the regenerator in an oxygen-containing atmosphere, the oxygen-containing regeneration gas fed through the oxygen-containing regeneration gas inlet 17 includes air, oxygen and the like, the regeneration temperature is 600-700℃, and the regenerated catalyst is recycled; part of the flue gas after regeneration is recycled back to the regenerator through the flue gas circulation pipeline 20.

[0193] The separated reaction oil gas enters the oil gas separation system 6 through the oil gas pipeline 5, after oil gas separation, the low carbon olefin outlet 7 obtains the low carbon olefin, the gaseous alkane outlet 8 obtains the gaseous alkane, the gasoline outlet 9 obtains the gasoline, the cycle oil outlet 10 obtains the cycle oil, and the oil slurry outlet 11 obtains the oil slurry; the gasoline is further extracted through the aromatic extraction system 24, the light aromatic outlet 25 obtains the light aromatic, and the raffinate outlet 26 obtains the raffinate; the cycle oil, the oil slurry and the raffinate can be selected to be reprocessed and / or not reprocessed according to production needs. The oil slurry can be reprocessed to enter the riser reactor, and the heavy raw material oil fed through the second heavy raw material oil inlet 27 is preferentially selected and / or atomized by the atomizing steam fed through the third atomizing steam inlet 28 to enter the riser reactor 21. In order to meet the demand for producing chemical materials, the raffinate is preferentially selected to be reprocessed, and can enter the riser reactor, and is preferentially selected to enter the bottom of the riser reactor 21, i.e. the lower part of the second heavy raw material oil inlet 27 for catalytic cracking reaction.

[0194] The application is further described in detail through the following examples, but the application is not limited thereto.

[0195] The light hydrocarbon raw material used in the examples is a certain refinery straight-run diesel and catalytic cracking diesel after hydrogenation in a mass ratio of 4:1 to produce hydrogenated diesel, and the heavy raw material oil is a certain refinery residual oil after hydrogenation to produce hydrogenated residual oil, and the properties of the two are shown in Table 1.

[0196] Table 1

[0197]

[0198]

[0199] The catalyst used in the examples is the same, and the preparation method is briefly described as follows:

[0200] 1) Dissolve 10 kg of NH4Cl in 500 kg of water, add 50 kg (dry basis) of the crystalline product DASY zeolite (produced by SINOPEC Qilu Catalyst Branch, cell constant 2.445-2.455 nm, rare earth content RE2O3 = 8.0 wt%) to the solution, exchange for 0.5 h at 90°C, filter to obtain a filter cake, add 1.6 kg of Fe(NO3)3.9H2O dissolved in 3.3 kg of water, impregnate the filter cake, dry, then calcine at 550°C for 2 h to obtain a large pore zeolite containing iron, having an elemental analysis chemical composition of 0.1 Na2O.5.1 Al2O3.1.5 Fe2O3.7.6 RE2O3.88.1 SiO2.

[0201] 2) Slurry 18.8 kg of high water content kaolin (industrial product of Suzhou Kaolin Co., solid content 71.6 wt%) with 125 kg of de-cationized water, then add 13.7 kg of pseudo-boehmite (industrial product of Shandong Aluminum Co., solid content 63 wt%), adjust the pH to 2-4 with hydrochloric acid, stir to uniform, stand and age at 60-70°C for 1 h, maintain the pH at 2-4, reduce the temperature to below 60°C, add 10.4 kg of aluminum sol (product of SINOPEC Qilu Catalyst Branch, Al2O3 content 21.7 wt%), stir for 40 min to obtain a mixed slurry.

[0202] 3) Add the large pore zeolite containing iron prepared in step 1) (8.5 kg dry basis) and the MFI structure mesopore ZRP-1 zeolite (industrial product of SINOPEC Qilu Catalyst Branch, SiO2 / Al2O3 = 30, phosphorus content P2O5 = 3.5 wt%, 5.3 kg dry basis) to the mixed slurry obtained in step 2), stir to uniform, mix, add an appropriate amount of water, stir to uniform, stand in air for 4 h, spray dry to form, dry in a drying oven at 120°C for 3 h, wash with ammonium dihydrogen phosphate solution (phosphorus content 1 wt%), wash to remove free Na + , wash to remove free Na + , dry again to obtain a catalyst, designated as CAT-2. The composition of the catalyst is 22.0 wt% DASY zeolite, 0.4 wt% iron oxide, 13.7 wt% MFI structure mesopore zeolite, 22.6 wt% pseudo-boehmite, 6.0 wt% aluminum sol and 35.3 wt% kaolin. The properties are listed in Table 2.

[0203] Table 2

[0204]

[0205]

[0206] Example 1

[0207] This example was carried out according toFigure 1 The system (flow) of Example 1 was tested using the hydrotreated diesel A in Table 1 as the raw material, and the test was carried out in an isokinetic fluidized bed reactor using the CAT-2 catalyst.

[0208] The hydrotreated diesel A was preheated to 300°C and then entered the bottom of the reaction section of the isokinetic fluidized bed reactor from the light hydrocarbon raw oil inlet 2. Under the reaction pressure of 0.25 MPa, water vapor was used as the fluidizing medium, the mass ratio of atomized steam to raw oil was 0.20, and the catalytic cracking reaction was carried out under the conditions of reaction temperature (measured at the outlet of the reactor, the same below) 600°C, weight ratio of catalyst to raw oil 10.0, and reaction time 4.0 seconds as the fluidizing medium flowed from bottom to top.

[0209] After the reaction, oil agent separation was carried out, and the separated reaction oil gas was subjected to product separation through the oil gas separation system 6 and the aromatic extraction system 24 to obtain dry gas, liquefied gas, gasoline, circulating oil, and oil slurry, etc. products, and the oil slurry part was recycled.

[0210] The spent catalyst after oil agent separation was sent to the regenerator after removing the oil gas adsorbed inside by steam stripping, and oxygen was used as the regeneration gas to contact with the spent catalyst at the regeneration temperature of 600-650°C for regeneration; the regenerated catalyst was recycled, and 60% of the flue gas after regeneration was recycled, and the circulating flue gas temperature was 600°C, and the dense phase temperature during regeneration was maintained at 650°C. The operating conditions and product distribution are listed in Table 3.

[0211] As can be seen from Table 3, in Example 1, the hydrotreated diesel was catalytically cracked in the isokinetic fluidized bed reactor, the liquefied gas yield was 37.69 wt%, the low-carbon olefin (ethylene + propylene + butene) yield was 35.63 wt%, the light aromatic hydrocarbon (benzene + toluene + xylene) yield was 10.19 wt%, the dry gas yield was 13.12 wt%, and the coke yield was 2.74 wt%.

[0212] Comparative Example 1

[0213] The same raw material oil and catalyst as in Example 1 and the same process conditions were used for catalytic cracking reaction, and the differences were as follows: 1) the riser reactor was used in Comparative Example 1; 2) air was used as the regeneration gas, and the flue gas was not recycled; 3) in order to maintain the same process conditions as in Example 1 for the reaction-regeneration system operation, it was necessary to spray combustion oil to provide heat in the regenerator. The operating conditions and product distribution are listed in Table 3.

[0214] As can be seen from Table 3, the liquefied gas yield and the low carbon olefin yield of Example 1 (isokinetic fluidized bed reactor) are higher than those of Comparative Example 1 (riser reactor), the liquefied gas yield is 4.17 percentage points higher than that of Comparative Example 1, and the low carbon olefin yield is 3.31 percentage points higher than that of Comparative Example 1; and the dry gas yield and the coke yield are lower, the dry gas yield is 2.05 percentage points lower than that of Comparative Example 1, and the coke yield is 1.21 percentage points lower than that of Comparative Example 1.

[0215] Example 2

[0216] This example is tested according to the system (flow) of Figure 2 , using hydrocracked diesel A and hydrocracked residue B in Table 1 as raw materials, which are respectively tested on the isokinetic fluidized bed reactor and the riser reactor, and CAT-2 catalyst is used.

[0217] The hydrocracked diesel A preheated to 240℃ enters the isokinetic fluidized bed reactor reaction section bottom from the light hydrocarbon raw material oil inlet 2, and the hydrocracked residue B preheated to 240℃ enters the conventional riser reactor bottom from the second heavy raw material oil inlet 27; both are under the reaction pressure of 0.32 MPa, water vapor as the fluidizing medium, the mass ratio of atomized steam to raw material oil is 0.15, and the catalytic cracking reaction is carried out with the fluidizing medium flowing from bottom to top in different reactors under the conditions of reaction temperature (based on the reactor outlet) 560℃, weight ratio of catalyst to raw material oil 7.7, and reaction time 8.0 seconds.

[0218] The oil-agent mixture (oil gas and catalyst) after the reaction of the hydrocracked residue B in the riser reactor is merged into the isokinetic fluidized bed reactor, and the oil-agent mixture after the reaction of the hydrocracked diesel A is separated together; the reaction oil gas after the oil-agent separation is subjected to product separation through the separation system and the aromatic extraction system to obtain dry gas, liquefied gas, gasoline, circulating oil and oil slurry, etc., and the oil slurry part is recycled.

[0219] The spent catalyst after the oil-agent separation is sent into the regenerator after the removal of the oil gas adsorbed inside by water vapor stripping, and the oxygen-enriched air with 25% oxygen and 75% air is used as the regeneration gas to contact with the spent catalyst at the regeneration temperature of 600-672℃ for regeneration; the regenerated catalyst is recycled, and part of the flue gas after the regeneration is recycled, the circulating flue gas temperature is 450℃, and the dense phase temperature of the regeneration is maintained at 672℃. The operating conditions and product distribution are listed in Table 3.

[0220] As can be seen from Table 3, in Example 2, the hydrocracking diesel oil is subjected to catalytic cracking reaction in the isokinetic fluidized bed reactor, and the hydrocracking residue is subjected to catalytic cracking reaction in the riser reactor, the liquefied gas yield is 34.02 wt%, the low carbon olefin (ethylene + propylene + butene) yield is 27.21 wt%, the light aromatic hydrocarbon (benzene + toluene + xylene) yield is 8.53 wt%, the dry gas yield is 5.38 wt%, and the coke yield is 4.61 wt%.

[0221] Comparative Example 2

[0222] The catalytic cracking reaction is carried out by using the same raw oil and catalyst as in Example 2 and the same process conditions, except that: 1) in Comparative Example 2, the hydrocracking diesel oil A and the hydrocracking residue B are both subjected to catalytic cracking reaction in the riser reactor; 2) air is used as the regeneration gas, and the flue gas is not recycled; 3) in order to maintain the same process conditions as in Example 2, it is necessary to provide heat in the regenerator by spraying combustion oil. 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), in Example 2 (isokinetic fluidized bed reactor + riser), the liquefied gas yield and the low carbon olefin yield are higher, the liquefied gas yield is 3.27 percentage points higher than that of Comparative Example 2, and the low carbon olefin yield is 2.39 percentage points higher than that of Comparative Example 2; and the dry gas yield and the coke yield are lower, the dry gas yield is 1.98 percentage points lower than that of Comparative Example 2, and the coke yield is 0.95 percentage points lower than that of Comparative Example 2.

[0224] Table 3

[0225]

[0226]

[0227] The inventors have found in the process of years of research and development that diesel catalytic cracking is different from heavy oil catalytic cracking, small molecules are difficult to crack, and therefore a higher reaction severity is required; the isokinetic fluidized bed reactor is suitable for a volume expansion reaction system and can reduce the dry gas and coke yields under high reaction severity of diesel; and the coke formation during diesel catalytic cracking is low, and it is difficult to maintain the heat required for the reaction by using conventional heavy oil regeneration technology.

[0228] In the variable-diameter isokinetic fluidized bed reactor, the diesel oil is subjected to catalytic cracking reaction at high temperature and a large catalyst / oil ratio by contacting with a high-activity catalyst, the coked catalyst is regenerated in an oxygen-rich and / or pure oxygen atmosphere, and part and / or all of the high-temperature flue gas after regeneration is returned to the regenerator, thereby achieving self-heat balance of the light hydrocarbon catalytic cracking reaction and regeneration, and achieving high conversion of light hydrocarbon catalytic cracking at a relatively high reaction temperature, and high-efficiency continuous production can be achieved.

[0229] In the description of the present application, it needs to be explained that the terms "upper", "lower", "inner", "outer", "front", "back", "left", "right" and the like indicate the orientation or positional relationship based on the working state of the present application, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0230] In the description of the present application, it needs to be explained that the terms "installation", "connection", "connection" should be understood broadly unless otherwise explicitly specified and limited. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0231] The above describes the present application in combination with the preferred embodiments, but these embodiments are only exemplary and serve only to illustrate. On this basis, various substitutions and improvements can be made to the present application, which all fall within the scope of protection of the present application.

Claims

1. A process for the catalytic cracking production of lower olefins and light aromatic hydrocarbons, characterized in that, The method comprises the following steps: (1) contacting raw oil with catalytic cracking catalyst in an isokinetic fluidized bed reactor to obtain an oil agent mixture; (2) separating the oil agent mixture to obtain a reaction oil gas and spent catalyst; (3) separating the reaction oil gas to obtain a low-carbon olefin component, a gasoline component and an oil slurry component; (4) performing aromatic extraction on the gasoline component to obtain a light aromatic component and a raffinate oil component; (5) regenerating the spent catalyst in a regenerator to obtain regenerated catalyst and flue gas; At least part of the regenerated catalyst is returned to the isokinetic fluidized bed reactor for recycling, and at least part of the flue gas is returned to the regenerator for recycling; The isokinetic fluidized bed reactor is provided with a variable-diameter reaction section, the inner diameter of the variable-diameter reaction section gradually increases from bottom to top, and the oil gas linear velocity of the variable-diameter reaction section is 1.0-2.0 m / s; The catalytic cracking catalyst comprises zeolite, the zeolite comprises mesoporous zeolite with an average pore size of 0.5-0.6 nm, the mass fraction of the mesoporous zeolite in the catalytic cracking catalyst is 10-20%, and the catalytic cracking catalyst further comprises macroporous zeolite, the mass fraction of the macroporous zeolite in the catalytic cracking catalyst is 20-40%.

2. The method of claim 1, wherein, The raw oil is diesel oil, and the diesel oil is fed into the isokinetic fluidized bed reactor from the lower part of the variable-diameter reaction section.

3. The method of claim 1, wherein, The raw oil is diesel oil, and the diesel oil is fed into the isokinetic fluidized bed reactor from the lower part of the variable-diameter reaction section; Furthermore, step (1) further comprises: contacting heavy oil with catalytic cracking catalyst in a riser reactor; In step (2), part of the oil agent mixture is derived from the contact reaction of the diesel oil and the catalytic cracking catalyst, and the other part is derived from the contact reaction of the heavy oil and the catalytic cracking catalyst; in step (5), part of the regenerated catalyst is returned to the isokinetic fluidized bed reactor for recycling, and the other part of the regenerated catalyst is returned to the riser reactor for recycling.

4. The method of claim 1, wherein, The raw oil comprises diesel oil and heavy oil, the diesel oil is fed into the isokinetic fluidized bed reactor from the lower part of the variable-diameter reaction section, and the heavy oil is fed into the isokinetic fluidized bed reactor from the middle part of the variable-diameter reaction section.

5. The method according to any one of claims 2-4, characterized in that, The diesel oil is selected from the group consisting of one or more combinations of straight-run diesel oil, catalytically cracked diesel oil and hydrogenated diesel oil; and / or, The diesel has a boiling point of 180 to 380°C and a density of less than or equal to 880 kg / m 3 .

6. The method according to claim 3 or 4, characterized in that, The heavy oil is wax oil and / or residual oil.

7. The method according to any one of claims 1 to 4, characterized in that, The catalytic cracking catalyst further comprises inorganic oxide, clay and modified oxide; The molar ratio of SiO2 and Al2O3 in the mesoporous zeolite and the macroporous zeolite is greater than 10; The inorganic oxide comprises alumina and / or silica; The mass fraction of the modified oxide in the catalytic cracking catalyst is 1.0-5.0%; The modified oxide is selected from the group consisting of one or more metal element oxides and / or non-metal element oxides of group IA, group IIA, group VA, group VIA, group VIIA, group IB, group IIB, group IIIB and group VIII; The average particle size of the catalytic cracking catalyst is 40-150 microns.

8. The method according to any one of claims 2-4, characterized in that, In step (1), the contacting reaction conditions of the diesel oil and the catalytic cracking catalyst in the isokinetic fluidized bed reactor include: The reaction temperature is 540-600℃, the reaction pressure is 0.2-0.5 MPa, the reaction time is 3.0-8.0 seconds, and the weight ratio of the catalytic cracking catalyst to the diesel oil is (5-10):1; The diesel oil is fed into the isokinetic fluidized bed reactor under the fluidization of a fluidizing medium; The fluidizing medium is atomized water, and the mass ratio of the atomized water to the diesel oil is (0.10-0.20):

1.

9. The method of claim 3, wherein, The contacting reaction conditions of the heavy oil and the catalytic cracking catalyst in the riser reactor include: The reaction temperature is 540-600℃, the reaction pressure is 0.2-0.5 MPa, the reaction time is 3.0-8.0 seconds, and the weight ratio of the catalytic cracking catalyst to the heavy oil is (5-10):1; The heavy oil is fed into the riser reactor under the fluidization of a fluidizing medium; The fluidizing medium is atomized water, and the mass ratio of the atomized water to the heavy oil is (0.10-0.20):1; The oil gas linear velocity of the riser reactor is 2.0-12.0 meters / second.

10. The method of claim 1, wherein, The method further includes the following steps before step (1): The raw oil is preheated to a preheating temperature, and the preheating temperature is 200-400℃; The preheating is heated by a heating furnace, or the raw oil is heat-exchanged with the product obtained from step (3) and / or step (4); and / or, In step (2), the separation of the oil agent mixture includes the following steps: The oil agent mixture is subjected to cyclone separation to obtain a first reaction oil gas and a spent catalyst containing oil gas; then, the spent catalyst containing oil gas is subjected to stripping to obtain the spent catalyst and a second reaction oil gas; The reaction oil gas includes the first reaction oil gas and the second reaction oil gas; and / or, The separation in step (3) further obtains gaseous alkanes and a cycle oil.

11. The method of claim 1, wherein, In step (5): The regeneration catalyst has a circulation rate of 150-200 kg / (m 2 ·sec). The regeneration atmosphere in the regenerator is selected from one or more combinations of air, oxygen-enriched air, and pure oxygen; The regeneration temperature in the regenerator is 600-700℃, and the pressure is 0.3-0.6 MPa; The flue gas is recycled to the regenerator after heat exchange, and the temperature of the flue gas recycled to the regenerator is 300-600℃.

12. The method of claim 1, wherein, At least part of the oil slurry component is fed into the isokinetic fluidized bed reactor from the middle part of the variable-diameter reaction section.

13. The method of claim 3, wherein, At least part of the oil slurry component and / or at least part of the raffinate oil component are fed into the riser reactor; wherein the feeding position of the raffinate oil component is below the feeding position of the heavy oil, and the oil slurry component is fed into the riser reactor through the feeding position of the heavy oil.

14. The method of claim 4, wherein, feeding at least part of the slurry component and / or at least part of the raffinate component into a variable-diameter reaction section of the isokinetic fluidized bed reactor; wherein the feeding position of the raffinate component is below the feeding position of the diesel, and the slurry component is fed from the feeding position of the heavy oil.

15. The method of claim 10, wherein, The preheating temperature is 220-320℃.

16. A system for catalytic cracking to produce lower olefins and light aromatic hydrocarbons, characterized by, The system comprises an isokinetic fluidized bed reactor (1), a cyclone separator (IV-1), a settler (IV), an oil-gas separation system (6), an aromatic extraction system (24) and a regenerator (16); The isokinetic 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 reactor reaction section (II) is connected between the outlet of the reactor pre-lifting section (I) and the inlet of the reactor outlet section (III); The reactor reaction section (II) is a variable-diameter reaction section, and the inner diameter of the reactor reaction section (II) gradually increases from bottom to top; the lower part of the reactor reaction section (II) is provided with a light hydrocarbon raw oil inlet (2) and a first atomizing steam inlet (3), and the first atomizing steam inlet (3) is in communication with the light hydrocarbon raw oil inlet (2); The oil agent outlet of the reactor outlet section (III) is in communication with the oil agent inlet of the cyclone separator (IV-1), the catalyst outlet of the cyclone separator (IV-1) is in communication with the inlet of the settler (IV), and the oil-gas outlet of the cyclone separator (IV-1) is in communication with the oil-gas inlet of the oil-gas separation system (6); The outlet of the settler (IV) is in communication with the catalyst inlet of the catalyst stripping section (IV-2), the catalyst outlet of the catalyst stripping section (IV-2) is in communication with the spent catalyst inlet of the regenerator (16), and the oil-gas outlet of the catalyst stripping section (IV-2) is in communication with the oil-gas inlet of the oil-gas separation system (6); The regenerator (16) is provided with an oxygen-containing regeneration gas inlet (17) and a flue gas outlet (19), the flue gas outlet (19) is in communication with the oxygen-containing regeneration gas inlet (17) through a flue gas circulation pipeline (20), the regenerated catalyst outlet of the regenerator (16) is in communication with the catalyst inlet of the reactor pre-lifting section (I) through a first regenerated agent conveying pipeline (18), and the bottom of the reactor pre-lifting section (I) is provided with a first fluidizing medium inlet (4); The oil-gas separation system (6) is provided with a low-carbon olefin outlet (7), a gaseous alkane outlet (8), a gasoline outlet (9), a circulating oil outlet (10) and a slurry outlet (11); the gasoline outlet (9) is in communication with the inlet of the aromatic extraction system (24), and the aromatic extraction system (24) is provided with a light aromatic outlet (25) and a raffinate outlet (26).

17. The system of claim 16, wherein, The system is also provided with a riser reactor (21) provided with a second heavy feed oil inlet (27) and a third atomizing steam inlet (28), the second heavy feed oil inlet (27) being in communication with the third atomizing steam inlet (28); The regenerated catalyst outlet of the regenerator (16) is in communication with the catalyst inlet at the bottom of the riser reactor (21) through a second regenerated catalyst conveying pipeline (23), and the bottom of the riser reactor (21) is also provided with a second fluidizing medium inlet (22); The oil catalyst outlet of the riser reactor (21) is in communication with the oil catalyst inlet of the cyclone separator (IV-1).

18. The system of claim 16, wherein, The oil gas outlet of the cyclone separator (IV-1) is in communication with the oil gas inlet of the oil gas separation system (6) through a reaction oil gas pipeline (5), and the oil gas outlet of the catalyst stripping section (IV-2) is in communication with the oil gas inlet of the oil gas separation system (6) through the reaction oil gas pipeline (5).

19. The system of claim 16, wherein, The lower part of the catalyst stripping section (IV-2) is provided with a stripping medium inlet (14).

20. The system of claim 16, wherein, The catalyst outlet of the catalyst stripping section (IV-2) is in communication with the spent catalyst inlet of the regenerator (16) through a spent catalyst conveying pipeline (15).

21. The system of claim 16, wherein, The middle part of the reactor reaction section (II) is provided with a first heavy feed oil inlet (12) and a second atomizing steam inlet (13), the first heavy feed oil inlet (12) being in communication with the second atomizing steam inlet (13).

22. The system of claim 21, wherein, The oil slurry outlet (11) is in communication with the first heavy feed oil inlet (12), and / or the reactor reaction section (II) is provided with a raffinate oil back-refining inlet in communication with the raffinate oil outlet (26), which is located below the light hydrocarbon feed oil inlet (2).

23. The system of claim 17, wherein, The oil slurry outlet (11) is in communication with the second heavy feed oil inlet (27), and / or the riser reactor (21) is provided with a raffinate oil inlet in communication with the raffinate oil outlet (26), which is located below the second heavy feed oil inlet (27).

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