Method and system for producing low-carbon olefin and light aromatic hydrocarbon through catalytic cracking

Abstract

The invention relates to a method and a system for producing low-carbon olefin and light aromatic hydrocarbon through catalytic cracking. The method comprises the following steps: (1) carrying out contact reaction on raw oil and a catalytic cracking catalyst in a constant linear velocity fluidized bed reactor to obtain an oil agent mixture; (2) separating the oil agent mixture to obtain reaction oil gas and a spent catalyst; and (3) separating the reaction oil gas to obtain a low-carbon olefin component, a gasoline component and an oil slurry component. In a constant-linear-speed fluidized bed reactor, light petroleum hydrocarbons such as diesel oil are contacted with a catalytic cracking catalyst with a high silica-alumina ratio, and self-heat balance is maintained through regeneration flue gas circulation to produce low-carbon olefins, light aromatic hydrocarbons and the like. According to the method disclosed by the invention, heavy oil such as naphtha, wax oil and residual oil can be processed while light hydrocarbon such as diesel oil is processed, the conversion rate of the diesel oil is high, self-heating balance can be realized, the problem of excessive diesel oil production capacity of a refinery plant is solved, and the processing benefit of crude oil is also improved.

Description

Technical Field

[0001] The present invention relates to the technical field of catalytic cracking of hydrocarbons, and in particular to a method and system for producing low-carbon olefins and light aromatics by catalytic cracking. Background Art

[0002] In recent years, the diesel-to-gasoline ratio in the refined oil market has been decreasing. After reaching a peak of 176Mt in 2014, diesel consumption has experienced zero or negative growth. According to statistics, the unit mileage emissions of a heavy-duty diesel vehicle are about 150 times that of a light-duty gasoline vehicle at the same stage, and the annual emissions are about 750 times that of a light-duty gasoline vehicle at the same stage. This pollution situation further restricts the development of diesel vehicles. It is expected that by 2025, diesel consumption will be reduced to 168Mt, and the diesel-to-gasoline ratio will be reduced from the current 1.4 to less than 1. This will mean that there will be a surplus of hundreds of millions of tons of diesel products, and the high particulate matter emissions of diesel engines will further restrict the use of diesel, and there will be a surplus of millions of tons of diesel for vehicles in tens of millions of tons of refineries. Reducing the diesel-to-gasoline ratio of refinery products and finding a way out for diesel have become urgent issues to be solved. Straight-run diesel accounts for about 50% of the total diesel volume. Reducing the output of straight-run diesel or converting it into other high-value-added products to adapt to future changes in diesel demand is of great significance to ensuring the balance of supply and demand in my country's refined oil market.

[0003] For the conversion of straight-run diesel, usually less than 10% of light diesel can be blended into ethylene cracking raw materials. However, compared with other light raw materials, the steam cracking olefin yield of straight-run diesel is lower and the decoking cycle is short. In addition, hydrocracking can process straight-run diesel, with a hydrogen consumption of 2.5%, a naphtha yield of 50% to 60%, and a liquefied gas yield of 4% to 5%. In recent years, domestic refineries have also adopted conventional catalytic cracking units to blend straight-run diesel in order to reduce the diesel-gasoline ratio. For example, the conventional catalytic cracking unit of Sinopec Hainan Refining and Chemical Co., Ltd. blends the three-line straight-run diesel, with a gasoline yield of 41%, but the volume fraction of propylene in the liquefied gas decreases by 0.52 percentage points and the volume fraction of isobutylene decreases by 0.12 percentage points, which is not conducive to increasing the production of low-carbon olefins.

[0004] The catalytic cracking of straight-run diesel alone or the catalytic cracking technology has progressed slowly. On the one hand, straight-run diesel has always been of high value as a high-cetane number vehicle fuel, with large usage and limited resources. On the other hand, the yield of catalytic cracking of straight-run diesel to produce gasoline or chemical materials such as ethylene and propylene is low. In addition, the coke production of straight-run diesel catalytic cracking is low, which is not enough to maintain the conventional fluidized bed catalytic cracking of self-thermal equilibrium, and the catalytic cracking requires a higher temperature.

[0005] Existing research at home and abroad has mainly focused on improving conversion rate and compensating for heat balance. For example, China National Petroleum Corporation's patent CN111607425A discloses a straight-run diesel cracking method, that is, the straight-run diesel with alkaline nitrogen removed by dihydrogen phosphate and inert gases such as nitrogen enter a fixed bed or moving bed reactor equipped with activated pretreated ZSM-5 nanomolecular sieve for catalytic cracking, and patent CN111718751A discloses a method for preparing a transition metal-modified ZSM-5 nanomolecular sieve catalyst in this method. As described in the two patents, the straight-run diesel uses a fixed bed reactor to heat the reaction temperature up to 600°C to achieve a diesel conversion rate of up to 80.16% and a light olefin yield of 34.13%; however, its one-way cycle is as short as 47 hours, and the short reaction cycle requires frequent switching of reactors, while the one-way cycle of the moving bed reactor is extended to 78 hours, but the operation is difficult.

[0006] Sinopec patents CN104418685B and CN104418686A both disclose a method for catalytic cracking of straight-run diesel in a riser reactor with methane as a diluent and the spent agent exchanging heat with flue gas. Patent CN104418686A also discloses a technology for extracting aromatics from cracked gasoline and steam cracking of C2-C4 alkanes. As described in the two patents, the use of mature fluidized bed technology can achieve continuous reaction-regeneration and solve the heat balance problem by setting up a spent agent and flue gas heat exchanger. At a reaction temperature of up to 630°C and a catalyst / oil mass ratio of 18, the diesel conversion rate of up to 83.83% and the ethylene and propylene yields of 16.52% and 35.19% were achieved through C4 recycling; however, the heat exchange between the spent agent and flue gas requires the addition of a heat exchanger, which is complex in process, high in equipment investment, and low in heat exchange efficiency. In addition, the flue gas contains a certain amount of oxygen and the spent agent is not fully burned, which is prone to tail combustion and other hidden dangers.

[0007] Therefore, given the difficulty in cracking light oil and the high severity of the reaction, how to better catalytically crack light oil to reduce the yield of dry gas and coke and increase the yield of high-value products such as low-carbon olefins and light aromatics is a technical problem that needs to be solved urgently. Summary of the invention

[0008] The present invention provides a method and system for producing low-carbon olefins and light aromatics by catalytic cracking, aiming to enable diesel to be better catalytically cracked to obtain high-value products such as low-carbon olefins and light aromatics with high yield.

[0009] In a first aspect, the present invention relates to a method for producing low-carbon olefins and light aromatics by catalytic cracking, the method comprising the following steps:

[0010] (1) contacting and reacting the crude oil with a catalytic cracking catalyst in a constant linear velocity fluidized bed reactor to obtain an oil-agent mixture;

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

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

[0013] (4) extracting aromatics from the gasoline component to obtain a light aromatic component and a raffinate component;

[0014] (5) allowing the regenerated catalyst to enter a regenerator for regeneration to obtain a regenerated catalyst and flue gas; returning at least a portion of the regenerated catalyst to the isolinear fluidized bed reactor for recycling, and returning at least a portion of the flue gas to the regenerator for recycling;

[0015] Wherein, the isolinear 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 zeolite, and the zeolite comprises a mesoporous zeolite with a ten-membered ring structure and an average pore diameter of 0.5 to 0.6 nm. The mass proportion of the mesoporous zeolite in the catalytic cracking catalyst is 10 to 20%.

[0017] Optionally, the feedstock oil is diesel, and the diesel is fed into the isolinear 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 isolinear fluidized bed reactor from the middle of the variable diameter reaction section.

[0019] Optionally, the feedstock oil is diesel, and the diesel is fed into the isolinear fluidized bed reactor from the lower part of the variable diameter reaction section;

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

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

[0022] In step (2), a portion of the oil mixture is derived from the contact reaction between the diesel and the catalytic cracking catalyst, and another portion is derived from the contact reaction between the heavy oil and the catalytic cracking catalyst; in step (5), a portion of the regenerated catalyst is returned to the isolinear fluidized bed reactor for recycling, and another portion of the regenerated catalyst is returned to the riser reactor for recycling;

[0023] Preferably, at least a portion of the slurry oil component and / or at least a portion of the raffinate oil component is fed into the riser reactor; wherein the feed position of the raffinate oil component is located below the feed position of the heavy oil, and the slurry oil component is fed into the riser reactor via the feed position of the heavy oil.

[0024] Optionally, the feedstock oil includes diesel and heavy oil, the diesel is fed into the isolinear fluidized bed reactor from the lower part of the variable diameter reaction section, and the heavy oil is fed into the isolinear fluidized bed reactor from the middle part of the variable diameter reaction section;

[0025] 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 isolinear fluidized bed reactor; wherein the feed position of the raffinate oil component is located below the feed position of the diesel, and the slurry oil component is fed from the feed position of the heavy oil.

[0026] Optionally, the diesel is selected from a combination of one or more of straight-run diesel, catalytic cracking diesel and hydrogenated diesel; and / or,

[0027] The boiling point of the diesel is 180-380°C and the density is less than or equal to 880kg / m 3 .

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

[0029] Optionally, the catalytic cracking catalyst further comprises large pore zeolite, inorganic oxide, clay and modified oxide;

[0030] The SiO in the medium-pore zeolite and the large-pore zeolite 2 and Al 2 O 3 The molar ratios are all greater than 10;

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

[0032] The inorganic oxide includes aluminum oxide and / or silicon oxide;

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

[0034] The modified oxide is selected from 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 to 150 microns.

[0036] Optionally, in step (1), the conditions for the contact reaction between the diesel and the catalytic cracking catalyst in a constant linear velocity fluidized bed reactor include:

[0037] 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;

[0038] The diesel is fed into the isolinear 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 is (0.10-0.20):1;

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

[0041] Optionally, the conditions for the contact reaction between the heavy oil and the catalytic cracking catalyst in the riser reactor include:

[0042] 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 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 and gas linear velocity of the riser reactor is 2.0-12.0 m / s.

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

[0047] Preheating the feedstock oil to a preheating temperature of 200 to 400° C., preferably 220 to 320° C.;

[0048] The preheating is performed by heating in a heating furnace, or the feedstock oil is subjected to heat exchange with the product obtained from step (3) and / or step (4); and / or,

[0049] In step (2), separating the oil mixture comprises the following steps:

[0050] The oil mixture is subjected to cyclone separation to obtain a first reaction oil gas and a catalyst to be regenerated containing the oil gas; then, the catalyst to be regenerated containing the oil gas is subjected to stripping to obtain the catalyst to be regenerated and a second reaction oil gas;

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

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

[0053] Optionally, in step (5):

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

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

[0056] The regeneration temperature in the regenerator is 600-700°C and the pressure is 0.3-0.6Mpa;

[0057] The flue gas is optionally returned to the regenerator for recycling after heat exchange, and the temperature of the flue gas returned to the regenerator for recycling is 300-600°C.

[0058] In a second aspect, the present invention relates to a system for producing low-carbon olefins and light aromatics by catalytic cracking, the system comprising a constant linear velocity fluidized bed reactor, a cyclone separator, a settler, an oil-gas separation system, an aromatics extraction system and a regenerator;

[0059] The isolinear 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; a light hydrocarbon feedstock oil inlet and a first atomizing steam inlet are arranged at the lower part of the reactor reaction section, and the first atomizing steam inlet is connected to the light hydrocarbon feedstock oil inlet;

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

[0063] The outlet of the settler is connected to the catalyst inlet of the catalyst stripping section, the catalyst outlet of the catalyst stripping section is connected to the catalyst inlet to be regenerated of the regenerator, and the oil and gas outlet of the catalyst stripping section is connected to the oil and gas inlet of the oil and gas separation system;

[0064] The regenerator is provided with an oxygen-containing regeneration gas inlet and a flue gas outlet, the flue gas outlet is connected to the oxygen-containing regeneration gas inlet through a flue gas circulation pipeline, the regeneration catalyst outlet of the regenerator is connected to the catalyst inlet of the reactor pre-lift section through a first regeneration agent delivery pipeline, and the bottom of the reactor pre-lift section is provided with a first fluidizing medium inlet;

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

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

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

[0068] Preferably, the catalyst outlet of the catalyst stripping section is connected to the catalyst inlet to be regenerated of the regenerator through a regenerated catalyst delivery pipeline;

[0069] Preferably, a first heavy feedstock oil inlet and a second atomizing steam inlet are provided in the middle of the reaction section of the reactor, and the first heavy feedstock oil inlet is connected to the second atomizing steam inlet;

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

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

[0072] The regenerated catalyst outlet of the regenerator is connected to the catalyst inlet at the bottom of the riser reactor through a second regeneration agent delivery pipeline, and a second fluidizing medium inlet is also provided at the bottom of the riser reactor;

[0073] The oil agent outlet of the riser reactor is connected to the oil agent inlet of the cyclone separator;

[0074] Preferably, the slurry oil outlet is connected to the second heavy feedstock oil inlet, and / or the riser reactor is provided with a raffinate oil inlet connected to the raffinate oil outlet, and the raffinate oil inlet is located below the second heavy feedstock oil inlet.

[0075] Beneficial effects:

[0076] The present invention allows diesel to contact with a catalytic cracking catalyst with a high silicon-aluminum ratio in a variable diameter reaction section of a constant linear velocity fluidized bed reactor to react, which can reduce the dry gas and coke yields under high reaction severity of diesel, and significantly improve the yields of low-carbon olefins and light aromatics; the high-temperature flue gas part after regeneration is completely returned to the regenerator for recycling, thereby achieving the self-heat balance of the diesel catalytic cracking reaction regeneration and realizing efficient continuous production. BRIEF DESCRIPTION OF THE DRAWINGS

[0077] Figure 1 It is a structural schematic diagram of a specific implementation method of a system for producing low-carbon olefins and light aromatics by catalytic cracking of the present invention;

[0078] Figure 2 It is a structural schematic diagram of another specific embodiment of a system for producing low-carbon olefins and light aromatics by catalytic cracking of the present invention;

[0079] Description of Reference Numerals

[0080] 1 isolinear fluidized bed reactor, 2 light hydrocarbon feedstock inlet, 3 first atomizing steam inlet,

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

[0082] 7 low carbon olefins export, 8 gas alkane export, 9 gasoline export,

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

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

[0085] 16 regenerator, 17 oxygen-containing regeneration gas inlet, 18 first regeneration agent delivery pipeline,

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

[0087] 22 second fluidizing medium inlet, 23 second regeneration agent delivery pipeline, 24 aromatics extraction system,

[0088] 25 light aromatics outlet, 26 raffinate oil outlet, 27 second heavy crude oil inlet,

[0089] 28 third atomizing steam inlet;

[0090] I reactor pre-lifting 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 present application is further described in detail below through the accompanying drawings and embodiments. Through these descriptions, the characteristics and advantages of the present application will become clearer and more specific.

[0093] The word "exemplary" is used exclusively herein to mean "serving as an example, embodiment, or illustration." Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments. Although various aspects of the embodiments are shown in the drawings, the drawings are not necessarily drawn to scale unless otherwise noted.

[0094] In addition, the technical features involved in different embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

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

[0096] (1) contacting and reacting the crude oil with a catalytic cracking catalyst in a constant linear velocity fluidized bed reactor to obtain an oil-agent mixture;

[0097] (2) separating the oil mixture to obtain reaction oil gas and a catalyst to be produced;

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

[0099] (4) extracting aromatics from the gasoline component to obtain a light aromatic component and a raffinate component;

[0100] (5) allowing the regenerated catalyst to enter a regenerator for regeneration to obtain a regenerated catalyst and flue gas; returning at least a portion of the regenerated catalyst to the isolinear fluidized bed reactor for recycling, and returning at least a portion of the flue gas to the regenerator for recycling;

[0101] Wherein, the isolinear 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 zeolite, and the zeolite comprises a mesoporous zeolite with a ten-membered ring structure and an average pore diameter of 0.5 to 0.6 nm. The mass proportion of the mesoporous zeolite in the catalytic cracking catalyst is 10 to 20%.

[0103] It should be noted that the method of the present invention is based on a catalytic cracking catalyst containing 10-20% of a medium-pore zeolite with a ten-membered ring structure having an average pore size of 0.5-0.6 nm, and the contact and reaction are carried out in an isolinear fluidized bed reactor, in particular, the inner diameter of the isolinear fluidized bed reactor gradually increases from bottom to top, which is conducive to better production of low-carbon olefins and light aromatics and other products from crude oil. And the flue gas obtained after regeneration in the regenerator is returned to the regenerator for recycling to maintain self-heating balance, and while achieving natural balance, it is also conducive to better production of low-carbon olefins and light aromatics and other products, which can improve the efficiency of crude oil processing.

[0104] According to a first specific implementation of the method of the first aspect of the present invention, the feedstock oil is diesel, and the diesel is fed into the isolinear 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 isolinear fluidized bed reactor from the middle of the variable diameter reaction section.

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

[0107] In particular, as a preferred embodiment, diesel is fed from the lower part of the variable diameter reaction section to the constant linear velocity fluidized bed reactor, so that at least part of the oil slurry component is fed from the middle part of the variable diameter reaction section to the constant linear velocity fluidized bed reactor for recycling, thereby being able to obtain light olefins and light aromatics with a higher yield.

[0108] According to a second specific implementation of the method described in the first aspect of the present invention, the feedstock oil is diesel, and the diesel is fed into the isolinear fluidized bed reactor from the lower part of the variable diameter reaction section;

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

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

[0111] In step (2), a portion of the oil mixture is derived from the contact reaction between the diesel and the catalytic cracking catalyst, and another portion is derived from the contact reaction between the heavy oil and the catalytic cracking catalyst; in step (5), a portion of the regenerated catalyst is returned to the isolinear fluidized bed reactor for recycling, and another portion of the regenerated catalyst is returned to the riser reactor for recycling;

[0112] Preferably, at least a portion of the slurry oil component and / or at least a portion of the raffinate oil component is fed into the riser reactor; wherein the feed position of the raffinate oil component is located below the feed position of the heavy oil, and the slurry oil component is fed into the riser reactor via the feed position of the heavy oil.

[0113] It should be noted that this embodiment is a process method for coupling catalytic cracking of an isolinear fluidized bed reactor with a riser reactor. In the method of this embodiment, while processing light hydrocarbons such as diesel, heavy oils such as naphtha, wax oil, and residual oil can also be processed. The diesel conversion rate is high, which not only solves the problem of excess diesel production capacity in refineries, but also improves the efficiency of crude oil processing.

[0114] Furthermore, as a preferred embodiment, diesel is fed from the lower part of the variable diameter reaction section into the isolinear fluidized bed reactor, and when the slurry oil component and the raffinate oil component are recycled, the slurry oil component is fed into the riser reactor through the feed position of the heavy oil, and the feed position of the raffinate oil component is located below the feed position of the heavy oil, which is conducive to obtaining a higher yield of low-carbon olefins and light aromatics, and better catalytic cracking of diesel and heavy oil.

[0115] According to a third specific implementation of the method according to the first aspect of the present invention, the feedstock oil includes diesel and heavy oil, the diesel is fed into the isolinear fluidized bed reactor from the lower part of the variable diameter reaction section, and the heavy oil is fed into the isolinear 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 isolinear fluidized bed reactor; wherein the feed position of the raffinate oil component is located below the feed position of the diesel, and the slurry oil component is fed from the feed position of the heavy oil.

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

[0118] According to a specific embodiment of the method according to the first aspect of the present invention, the diesel is selected from a combination of one or more of straight-run diesel, catalytic cracking diesel and hydrogenated diesel; and / or,

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

[0120] It should be noted that the method of the present invention has a wide range of applicability. In addition to the above-mentioned diesel, it can also be applied to the catalytic cracking of other light hydrocarbon oils, and the present invention is not limited. Using the above-mentioned diesel as the feedstock oil for catalytic cracking in an isolinear fluidized bed reactor can solve the problem of diesel excess and convert diesel into products such as gasoline and liquefied gas.

[0121] According to a specific implementation of the method described in the first aspect of the present invention, the heavy oil is wax oil and / or residual oil.

[0122] It should be noted that the method of the present invention has wide applicability, and in addition to the above-mentioned wax oil and residual oil, it can also be applied to the catalytic cracking of other heavy oils. Wax oil and / or residual oil are used as heavy oil, and catalytic cracking is carried out together with diesel in an isolinear fluidized bed reactor, or diesel and heavy oil are catalytically cracked in an isolinear fluidized bed reactor and a riser reactor, respectively, and in particular, the feed is carried out according to the feed position in the above-mentioned specific embodiment, and the heavy oil and diesel can be better converted into high-value products such as light olefins and light aromatics through catalytic cracking.

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

[0124] The SiO in the medium-pore zeolite and the large-pore zeolite 2 and Al 2 O 3 The molar ratios are all greater than 10;

[0125] The mass proportion of the large-pore zeolite in the catalytic cracking catalyst is 20-40%;

[0126] The inorganic oxide includes aluminum oxide and / or silicon oxide;

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

[0128] The modified oxide is selected from 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;

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

[0130] It should be noted that in the method for producing low-carbon olefins and light aromatics by catalytic cracking of the present invention, the catalyst used is a high silicon-aluminum ratio catalytic cracking catalyst, which contains both medium-pore zeolite and large-pore zeolite, wherein SiO 2 and Al 2 O 3 The molar ratio of SiO 2 and Al 2 O 3 The molar ratio, i.e., the silicon-to-aluminum ratio, can be 15, 20, 25, 30, or 35 or more.

[0131] The mass proportions of inorganic oxide and clay in the catalytic cracking catalyst may be 15-34% and 20-35% respectively; the large-pore zeolite may be selected from one or more of REY zeolite, HY zeolite, REHY zeolite, ultrastable Y zeolite (USY zeolite), high-silicon Y zeolite and β zeolite, preferably high-silicon-aluminum ratio ultrastable Y zeolite, and its total silicon-aluminum ratio (SiO 2 and Al 2 O 3 The molar ratio of the above-mentioned metal oxides is higher than 10. The medium-pore zeolite is one or more selected from 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 one or more selected from silicon dioxide, kaolin, halloysite, montmorillonite, diatomaceous earth, halloysite, saponite, rectorite, sepiolite, attapulgite, hydrotalcite and bentonite. The modified oxide composed of the metal oxide and / or non-metal oxide can be selected from one or more oxides of elements in Group IA, Group IIA, Group VA, Group VIA, Group VIIA, Group IB, Group IIB, Group IIIB and Group VIII, and can be an oxide of a transition metal element or a non-transition metal element.

[0132] It should be noted that in the method of the present invention, diesel, or diesel and heavy oil, are contacted with the above-mentioned catalytic cracking catalyst in a constant linear velocity fluidized bed reactor, or in a constant linear velocity fluidized bed reactor and a riser reactor to carry out catalytic cracking reaction, which can further improve the conversion rate of the crude oil and better prepare high-value products.

[0133] According to another specific embodiment of the method of the first aspect of the present invention, in step (1), the conditions for the contact reaction between the diesel and the catalytic cracking catalyst in the isolinear 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 isolinear fluidized bed reactor under fluidization of a fluidizing medium;

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

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

[0138] It should be noted that in the method of the present invention, by controlling the conditions of the contact reaction in step (1) as described above, diesel can be better converted into low-carbon olefins and light aromatics under the catalysis of the catalytic cracking catalyst.

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

[0140] 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 heavy oil is (5-10):1;

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

[0142] The fluidizing 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 and gas linear velocity of the riser reactor is 2.0-12.0 m / s.

[0144] It should be noted that controlling the contact reaction conditions between the heavy oil and the catalytic cracking catalyst in the riser reactor as described above can better convert the heavy oil into high-value products such as low-carbon olefins and light aromatics through catalytic cracking.

[0145] According to a specific implementation of the method according to the first aspect of the present invention, the method further comprises the following steps before step (1):

[0146] Preheating the feedstock oil to a preheating temperature of 200 to 400° C., preferably 220 to 320° C.;

[0147] The preheating is performed by heating in a heating furnace, or the feedstock oil is subjected to heat exchange with the product obtained from step (3) and / or step (4); and / or,

[0148] In step (2), separating the oil mixture comprises the following steps:

[0149] The oil mixture is subjected to cyclone separation to obtain a first reaction oil gas and a catalyst to be regenerated containing the oil gas; then, the catalyst to be regenerated containing the oil gas is subjected to stripping to obtain the catalyst to be regenerated 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) also yields gaseous alkanes and cycle oil.

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

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

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

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

[0156] The regeneration temperature in the regenerator is 600-700°C and the pressure is 0.3-0.6Mpa;

[0157] The flue gas is optionally returned to the regenerator for recycling after heat exchange, and the temperature of the flue gas returned to the regenerator for recycling is 300-600°C.

[0158] It should be noted that the oxygen-containing high-temperature flue gas obtained after catalyst regeneration in the regenerator can be returned to the regenerator for recycling without heat exchange or after partial heat exchange, which can make full use of the oxygen in the flue gas and maintain a high regeneration temperature of the regenerator and a high regeneration agent temperature. The regeneration atmosphere in the regenerator is preferably oxygen-enriched and / or pure oxygen. Compared with conventional air regeneration, less heat is required to heat the regeneration gas, the charring intensity is high, the regeneration temperature is also high, and a high regeneration agent temperature can be maintained. The high-temperature flue gas after regeneration is partially and / or completely returned to the regenerator, which not only makes full use of the oxygen in the flue gas, but also solves the problem of the flue gas carrying heat outside the regeneration system, and reduces the emission of waste gases such as carbon dioxide, thereby significantly saving energy and reducing emissions.

[0159] In a second aspect, the present invention relates to a system for catalytic cracking to produce light olefins and light aromatics, such as Figure 1 As shown, the system includes a constant linear velocity fluidized bed reactor 1, a cyclone separator IV-1, a settler IV, an oil-gas separation system 6, an aromatics extraction system 24 and a regenerator 16;

[0160] The isolinear 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-lift 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; a light hydrocarbon feedstock oil inlet 2 and a first atomizing steam inlet 3 are provided at the lower part of the reactor reaction section II, and the first atomizing steam inlet 3 is connected to the light hydrocarbon feedstock oil inlet 2;

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

[0164] The outlet of the settler IV is connected to the catalyst inlet of the catalyst stripping section IV-2, the catalyst outlet of the catalyst stripping section IV-2 is connected to the catalyst inlet to be regenerated of the regenerator 16, and the oil and gas outlet of the catalyst stripping section IV-2 is connected to the oil and gas inlet of the oil and gas separation system 6;

[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 connected to the oxygen-containing regeneration gas inlet 17 through a flue gas circulation pipeline 20, the regeneration catalyst outlet of the regenerator 16 is connected to the catalyst inlet of the reactor pre-lift section I through a first regeneration agent delivery pipeline 18, and the bottom of the reactor pre-lift section I is provided with a first fluidizing medium inlet 4;

[0166] The oil-gas separation system 6 is provided with a light olefin outlet 7, a gas alkane outlet 8, a gasoline outlet 9, a circulating oil outlet 10 and an oil slurry outlet 11; the gasoline outlet 9 is connected to 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 oil outlet 26;

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

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

[0169] Preferably, the catalyst outlet of the catalyst stripping section IV-2 is connected to the catalyst inlet to be regenerated of the regenerator 16 through the catalyst transport pipeline 15;

[0170] Preferably, a first heavy feedstock oil inlet 12 and a second atomizing steam inlet 13 are provided in the middle of the reaction section II of the reactor, and the first heavy feedstock oil inlet 12 is connected to the second atomizing steam inlet 13;

[0171] Preferably, the oil slurry outlet 11 is connected to the first heavy feedstock oil inlet 12, and / or the reactor reaction section II is provided with a raffinate oil recycling inlet connected to the raffinate oil outlet 26, and the raffinate oil recycling inlet is located below the light hydrocarbon feedstock oil inlet 2.

[0172] The constant linear velocity fluidized bed reactor described in the present invention refers to a fluidized bed reactor in which the oil and gas in the catalytic cracking reaction maintain a relatively uniform linear velocity. Compared with an ordinary fluidized bed with a uniform diameter, the oil and gas in the constant linear velocity fluidized bed reactor contact the catalyst in a plug flow state at a uniform linear velocity, the catalyst density is high, and the oil and gas contact is more complete.

[0173] It should be noted that the catalyst in the constant linear velocity fluidized bed reactor 1 can flow in an upward manner or in a downward manner; preferably, the catalyst flows in an upward manner. The constant linear velocity fluidized bed reactor 1 and the regenerator 16 can be arranged in parallel or overlapped, and the constant linear velocity fluidized bed reactor 1 and the settler IV can be built-in or external; the catalyst is lifted by a medium such as air and / or water vapor, so that it circulates between the reactor and the regenerator.

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

[0175] In these two specific embodiments, the oil mixture after the reaction flows upward to the reactor outlet section III, and then enters the cyclone separator IV-1 for cyclone separation, the separated reaction oil and gas flow to the oil-gas separation system 6 for oil-gas separation, the separated regenerated catalyst containing reaction oil and gas enters the settler IV, and after sedimentation, enters the catalyst stripping section IV-2 for stripping, and the regenerated catalyst and reaction oil and gas are obtained through stripping. The obtained regenerated catalyst enters the regenerator 16 for regeneration, and the obtained reaction oil and 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 regenerated catalyst is regenerated in the oxygen-containing atmosphere. The obtained regenerated catalyst can be returned to the isolinear fluidized bed reactor 1 through the first regeneration agent delivery pipeline 18 for recycling. The obtained high-temperature flue gas flows out through the flue gas outlet 19, and then can be partially or completely returned to the regenerator 16 for recycling through the flue gas circulation pipeline 20.

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

[0178] According to another specific implementation of the system according to the second aspect of the present invention, Figure 2 As shown, the system is further provided with a riser reactor 21, and the riser reactor 21 is provided with a second heavy feedstock oil inlet 27 and a third atomizing steam inlet 28, and the second heavy feedstock oil inlet 27 is connected to the third atomizing steam inlet 28;

[0179] The regenerated catalyst outlet of the regenerator 16 is connected to the catalyst inlet at the bottom of the riser reactor 21 through a second regeneration agent delivery pipeline 23. The bottom of the riser reactor 21 is also provided with a second fluidizing medium inlet 22;

[0180] The oil agent outlet of the riser reactor 21 is connected to the oil agent inlet of the cyclone separator IV-1;

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

[0182] It should be noted that, in this embodiment, diesel is fed to the reactor reaction section II of the isolinear fluidized bed reactor 1 through the light hydrocarbon feedstock inlet 2, and heavy oil is fed to the riser reactor 21 through the second heavy feedstock inlet 27; diesel and the catalytic cracking catalyst are contacted and reacted in the isolinear fluidized bed reactor 1, and the heavy oil and the catalytic cracking catalyst are contacted and reacted in the riser reactor 21. The oil mixture 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 mixtures are separated in one cyclone separator, and the reaction oil gas and the catalyst to be produced are separated through separation, sedimentation and extraction.

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

[0184] A specific implementation of the present disclosure is as follows: Figure 1 As shown, in this embodiment, an upward variable diameter constant linear velocity fluidized bed reactor 1 is used, and light hydrocarbon feedstock oil enters the reactor through a light hydrocarbon feedstock oil inlet 2 by downward feeding to contact the regeneration agent for catalytic cracking reaction, and the spent agent after the reaction is separated from the oil and gas and then regenerated, and the regenerated flue gas is partially circulated back to the regenerator. The process flow is as follows:

[0185] The light hydrocarbon feedstock oil fed through the light hydrocarbon feedstock 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 isolinear fluidized bed reactor 1, while the hot regenerated agent is introduced into the reactor pre-lifting section I of the isolinear fluidized bed reactor 1 through the first regenerated agent delivery pipeline 18, and ascends 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 feedstock oil contacts the hot regenerated agent to undergo catalytic cracking reaction.

[0186] After the reaction, the oil gas and the catalyst enter the cyclone separator IV-1 through the reactor outlet section III for oil-agent separation. The separated catalyst is settled to the catalyst stripping section IV-2 through the settler IV. The regenerated catalyst is stripped by the stripping medium entering through the stripping medium inlet 14 and enters the regenerator 16 through the regenerated catalyst delivery pipeline 15.

[0187] The regenerated catalyst is regenerated in an oxygen-containing atmosphere in the regenerator. The oxygen-containing regeneration gas entering through the oxygen-containing regeneration gas inlet 17 includes air, oxygen, etc. The regeneration temperature is 600-700°C. The regenerated catalyst is recycled; the regenerated flue gas part is circulated back to the regenerator through the flue gas circulation pipeline 20.

[0188] The separated reaction oil and gas enter the oil and gas separation system 6 through the reaction oil and gas pipeline 5. After oil and gas separation, the light olefins are obtained at the light olefin outlet 7, the gas alkane outlet 8 is obtained at the gas alkane outlet 8, the gasoline is obtained at the gasoline outlet 9, the circulating oil outlet 10 is obtained at the circulating oil outlet 11, and the oil slurry outlet 11 is obtained at the oil slurry; and the gasoline is further extracted through the aromatics extraction system 24, the light aromatics are obtained at the light aromatics outlet 25, and the raffinate oil outlet 26 is obtained at the raffinate oil outlet; wherein the circulating oil, the oil slurry and the raffinate oil can be recycled and / or not recycled according to production needs. In order to meet the needs of the device's self-heating balance, the oil slurry and / or circulating oil recycling is preferred; the oil slurry is recycled, and / or the heavy feedstock oil is atomized by the atomizing steam 13 entering through the first heavy feedstock oil inlet 12 and the second atomizing steam inlet 13 and then enters the reactor, preferably entering the middle of the reactor reaction section II, that is, feeding at the upper part of the light hydrocarbon feedstock oil inlet 2. Due to the demand for more chemical materials, the raffinate oil is preferably recycled; the raffinate oil can be mixed with light crude oil and then enter the reactor, preferably enter the bottom of the reactor reaction section II, that is, it can be fed at the lower part of the light hydrocarbon crude oil inlet 2.

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

[0190] The light hydrocarbon feedstock oil entering through the light hydrocarbon feedstock oil 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 reactor reaction section II of the isolinear fluidized bed reactor 1, while the hot regeneration agent is introduced into the reactor pre-lifting section I of the isolinear fluidized bed reactor through the first regeneration agent delivery pipeline 18, and ascends into the reactor reaction section II under the fluidization of the fluidizing medium entering through the first fluidizing medium inlet 4, and the light hydrocarbon feedstock oil contacts the hot regeneration agent to undergo catalytic cracking reaction.

[0191] The heavy crude oil is fed through the second heavy crude oil 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, while the hot regenerated agent is introduced into the bottom of the riser reactor through the second regenerated agent delivery pipeline 23, and moves upward under the fluidization of the fluidizing medium fed through the second fluidizing medium inlet 22, and the heavy crude oil contacts the hot regenerated agent to undergo catalytic cracking reaction.

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

[0193] The separated reaction oil and gas enter the oil and gas separation system 6 through the reaction oil and gas pipeline 5. After oil and gas separation, the low-carbon olefin outlet 7 obtains low-carbon olefins, the gas alkane outlet 8 obtains gas alkane, the gasoline outlet 9 obtains gasoline, the circulating oil outlet 10 obtains circulating oil, and the oil slurry outlet 11 obtains oil slurry; and the gasoline is further extracted through the aromatics extraction system 24, the light aromatics outlet 25 obtains light aromatics, and the raffinate oil outlet 26 obtains raffinate oil; wherein the circulating oil, slurry oil and raffinate oil can be recycled and / or not recycled according to production needs. The oil slurry is recycled and can enter the riser reactor, and the heavy raw material oil fed by the second heavy raw material oil inlet 27 is preferentially selected and / or the atomizing steam entering through the third atomizing steam inlet 28 enters the riser reactor 21 after being atomized. In order to produce more chemical materials, the raffinate oil is preferentially recycled and can enter the riser reactor, and preferentially enters the bottom of the riser reactor 21, that is, the feed at the lower part of the second heavy raw material oil inlet 27 is fed for catalytic cracking reaction.

[0194] The present invention is further described in detail below by way of examples, but the present invention is not limited thereto.

[0195] The light hydrocarbon feedstock used in the embodiment is hydrogenated diesel produced by hydrogenating straight-run diesel and catalytic cracking diesel in a refinery at a mass ratio of 4:1, and the heavy feedstock oil is hydrogenated residue oil after hydrogenation of residue oil in a refinery. The properties of the two are shown in Table 1.

[0196] Table 1

[0197]

[0198]

[0199] The catalysts used in the examples are the same, and their preparation methods are briefly described as follows:

[0200] 1) 10kgNH 4 Cl was dissolved in 500 kg of water, and 50 kg (dry basis) of crystallized DASY zeolite (produced by Sinopec Catalyst Qilu Branch, unit cell constant 2.445-2.455 nm, rare earth content RE 2 O 3 =8.0 wt%), exchanged at 90°C for 0.5h, filtered to obtain a filter cake; added 1.6 kgFe(NO 3 ) 3 9H 2 O was dissolved in 3.3 kg of water, mixed with the filter cake, impregnated and dried; then calcined at 550 ° C for 2 hours to obtain an iron-containing macroporous zeolite, whose elemental analysis chemical composition is 0.1 Na 2 O.5.1Al 2 O 3 1.5Fe 2 O 3 7.6RE 2 O 3 88.1SiO 2 .

[0201] 2) Use 125kg of decationized water to slurry 18.8kg of halloysite (industrial product of Suzhou Clay Company, solid content 71.6m%), then add 13.7kg of pseudo-boehmite (industrial product of Shandong Aluminum Plant, solid content 63m%), adjust the pH to 2-4 with hydrochloric acid, stir evenly, stand and age at 60-70℃ for 1 hour, keep the pH at 2-4, lower the temperature to below 60℃, add 10.4kg of aluminum sol (product of Sinopec Catalyst Qilu Branch, Al 2 O 3 The content is 21.7m%), stirred for 40 minutes to obtain a mixed slurry.

[0202] 3) The iron-containing macroporous zeolite (8.5 kg on a dry basis) prepared in step 1) and the medium-pore ZRP-1 zeolite with MFI structure (industrial product of Sinopec Catalyst Qilu Branch, SiO 2 / Al 2 O 3 =30, phosphorus content P 2 O 5 =3.5 wt%, dry basis 5.3 kg) was added to the mixed slurry obtained in step 2), stirred evenly, put into a bonding machine after mixing, added appropriate amount of water, stirred evenly, placed in the air for 4 hours, spray dried to form, dried in a drying oven at 120°C for 3 hours, and washed with ammonium dihydrogen phosphate solution (phosphorus content 1m%) to wash away free Na + , washing to remove free Na + The catalyst was dried again and recorded as CAT-2. The composition of the catalyst was 22.0 wt% DASY zeolite, 0.4 wt% iron oxide, 13.7 wt% MFI structure medium pore zeolite, 22.6 wt% pseudo-boehmite, 6.0 wt% aluminum sol and 35.3% kaolin. Its properties are listed in Table 2.

[0203] Table 2

[0204]

[0205]

[0206] Example 1

[0207] This embodiment follows Figure 1 The system (process) was tested, using the hydrogenated diesel A in Table 1 as the raw material, and the test was carried out in an isolinear fluidized bed reactor using a CAT-2 catalyst.

[0208] Hydrogenated diesel A was preheated at 300°C and then entered the bottom of the reaction section of the isolinear fluidized bed reactor from the light hydrocarbon feedstock inlet 2. At a reaction pressure of 0.25 MPa, water vapor was used as the fluidizing medium, and the mass ratio of atomized steam to feedstock was 0.20. As the fluidizing medium flowed from bottom to top, a catalytic cracking reaction was carried out at a reaction temperature (based on the reactor outlet, the same below) of 600°C, a weight ratio of catalyst to feedstock of 10.0, and a reaction time of 4.0 seconds.

[0209] After the reaction, the oil agent is separated, and the separated reaction oil and gas are separated into products such as dry gas, liquefied gas, gasoline, circulating oil and oil slurry through the oil and gas separation system 6 and the aromatics extraction system 24, and the oil slurry is partially recycled.

[0210] After the oil and agent are separated, the catalyst to be regenerated is stripped by steam to remove the oil and gas adsorbed inside it, and then sent to the regenerator. Oxygen is used as the regeneration gas, and it is regenerated at a regeneration temperature of 600-650℃ in contact with the catalyst to be regenerated; the regenerated regenerated agent is recycled, 60% of the flue gas after regeneration is recycled, the circulating flue gas temperature is 600℃, and the regeneration dense phase temperature is maintained at 650℃. The operating conditions and product distribution are listed in Table 3.

[0211] As can be seen from Table 3, in Example 1, the hydrogenated diesel was subjected to catalytic cracking reaction in a constant linear velocity fluidized bed reactor, and the yield of liquefied gas was 37.69% by weight, the yield of light olefins (ethylene + propylene + butene) was 35.63% by weight, and the yield of light aromatics (benzene + toluene + xylene) was 10.19% by weight; while the dry gas yield was 13.12% by weight and the coke yield was 2.74% by weight.

[0212] Comparative Example 1

[0213] The catalytic cracking reaction was carried out by using the same feedstock oil, catalyst and process conditions as in Example 1, except that: 1) the riser reactor was used in Example 1; 2) air was used as the regeneration gas, and the flue gas was not circulated; 3) in order to maintain the same process conditions as in Example 1, it was necessary to spray combustion oil in the regenerator to provide heat. The operating conditions and product distribution are listed in Table 3.

[0214] As can be seen from Table 3, compared with Comparative Example 1 (riser reactor), Example 1 (constant linear velocity fluidized bed reactor) has high liquefied gas yield and low carbon olefin yield, 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 and coke yields are low, 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 embodiment follows Figure 2 The system (process) was tested, using hydrogenated diesel A and hydrogenated residue B in Table 1 as raw materials. The two were tested in an isolinear fluidized bed reactor and a riser reactor respectively, using CAT-2 catalyst.

[0217] Hydrogenated diesel A is preheated at 240° C. and enters the bottom of the reaction section of the isolinear fluidized bed reactor from the light hydrocarbon feedstock inlet 2. Hydrogenated residue B is preheated at 240° C. and enters the bottom of the conventional riser reactor from the second heavy feedstock inlet 27. Both are at a reaction pressure of 0.32 MPa, with water vapor as the fluidizing medium, and a mass ratio of atomized steam to feedstock of 0.15. As the fluidizing medium flows from bottom to top in different reactors, catalytic cracking reactions are carried out at a reaction temperature (based on the reactor outlet) of 560° C., a weight ratio of catalyst to feedstock of 7.7, and a reaction time of 8.0 seconds.

[0218] The oil-agent mixture (oil gas and catalyst) after the reaction of the hydrogenated residue oil B in the riser reactor is introduced into the isolinear fluidized bed reactor and separated from the oil-agent mixture after the reaction of the hydrogenated diesel A; the reaction oil and gas after the oil-agent separation are separated into products through the separation system and the aromatic extraction system to obtain dry gas, liquefied gas, gasoline, circulating oil, oil slurry and other products, and the oil slurry is partially recycled.

[0219] The catalyst to be regenerated after oil separation is sent to the regenerator after steam stripping to remove the oil and gas adsorbed inside. The oxygen-enriched air with 25% oxygen and 75% air is used as the regeneration gas, and the catalyst is regenerated at a regeneration temperature of 600-672°C. The regenerated regenerated agent is recycled, and the flue gas after regeneration is partially recycled. The circulating flue gas temperature is 450°C, and the regeneration dense phase temperature is maintained at 672°C. The operating conditions and product distribution are listed in Table 3.

[0220] As can be seen from Table 3, in Example 2, the hydrogenated diesel was subjected to catalytic cracking reactions in a constant linear velocity fluidized bed reactor and the hydrogenated residue was subjected to catalytic cracking reactions in a riser reactor at the same time, and the liquefied gas yield of the two was 34.02% by weight, the light olefins (ethylene + propylene + butene) yield was 27.21% by weight, and the light aromatics (benzene + toluene + xylene) yield was 8.53% by weight; while the dry gas yield was 5.38% by weight and the coke yield was 4.61% by weight.

[0221] Comparative Example 2

[0222] The catalytic cracking reaction was carried out by using the same feedstock oil, catalyst and process conditions as in Example 2, except that: 1) both hydrogenated diesel A and hydrogenated residue B in Example 2 used riser reactors; 2) air was used as the regeneration gas, and the flue gas was not circulated; 3) in order to maintain the same process conditions as in Example 2 for the operation of the reverse regeneration system, it was necessary to spray combustion oil in the regenerator to provide heat. The operating conditions and product distribution are listed in Table 3.

[0223] As can be seen from Table 3, compared with Comparative Example 2 (riser reactor), Example 2 (constant linear velocity fluidized bed reactor + riser) has high liquefied gas yield and low carbon olefin yield, 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 and coke yields are low, 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 of this application innovatively discovered during many years of research and development that diesel catalytic cracking is different from heavy oil catalytic cracking. Small molecules are difficult to crack, which requires a higher reaction severity. The isolinear fluidized bed reactor is suitable for volume expansion reaction systems and can reduce the dry gas and coke yields under high reaction severity of diesel. The catalytic cracking of diesel has low coke production, and it is difficult to maintain the heat required for its own reaction through self-heating balance using conventional heavy oil regeneration technology.

[0228] In the present application, in a variable diameter equal linear velocity fluidized bed reactor, diesel is contacted with a high-activity catalyst to carry out a catalytic cracking reaction at a high temperature and a large dose-to-oil ratio, the coked and deactivated catalyst is regenerated in an oxygen-rich and / or pure oxygen atmosphere, and part or all of the high-temperature flue gas after regeneration is returned to the regenerator, thereby achieving the self-heat balance of the regeneration of the catalytic cracking reaction of light hydrocarbons, and achieving a higher conversion rate of the catalytic cracking of light hydrocarbons at a higher reaction temperature, and realizing efficient continuous production.

[0229] In the description of the present application, it should be noted that the terms "upper", "lower", "inside", "outside", "front", "back", "left", "right", etc. indicate directions or positional relationships based on the directions or positional relationships in the working state of the present application. They are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they should not be understood as limitations on the present application.

[0230] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "install", "connect" and "connect" should be understood in a broad sense. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0231] The present application has been described above in conjunction with preferred embodiments, but these embodiments are only exemplary and serve only as an illustration. On this basis, various replacements and improvements may be made to the present application, all of which fall within the scope of protection of the present application.

Claims

1. A method for producing low-carbon olefins and light aromatics by catalytic cracking, characterized in that: The method comprises the following steps: (1) contacting and reacting the crude oil with a catalytic cracking catalyst in a constant linear velocity fluidized bed reactor to obtain an oil-agent mixture; (2) separating the oil mixture to obtain reaction oil gas and a catalyst to be produced; (3) separating the reaction oil and gas to obtain a light olefin component, a gasoline component and an oil slurry component; (4) extracting aromatics from the gasoline component to obtain a light aromatic component and a raffinate component; (5) allowing the catalyst to be regenerated to enter a regenerator for regeneration to obtain a regenerated catalyst and flue gas; Returning at least part of the regenerated catalyst to the isolinear fluidized bed reactor for recycling, and returning at least part of the flue gas to the regenerator for recycling; Wherein, the isolinear 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; The catalytic cracking catalyst comprises zeolite, and the zeolite comprises a mesoporous zeolite with a ten-membered ring structure and an average pore diameter of 0.5 to 0.6 nm. The mass proportion of the mesoporous zeolite in the catalytic cracking catalyst is 10 to 20%.

2. The method according to claim 1, characterized in that The raw oil is diesel, and the diesel is fed into the isolinear fluidized bed reactor from the lower part of the variable diameter reaction section; Preferably, at least part of the oil slurry component is fed into the isolinear fluidized bed reactor from the middle of the variable diameter reaction section.

3. The method according to claim 1, characterized in that The raw oil is diesel, and the diesel is fed into the isolinear fluidized bed reactor from the lower part of the variable diameter reaction section; Furthermore, step (1) further comprises: contacting and reacting the heavy oil with a catalytic cracking catalyst in a riser reactor; In step (2), a portion of the oil mixture is derived from the contact reaction between the diesel and the catalytic cracking catalyst, and another portion is derived from the contact reaction between the heavy oil and the catalytic cracking catalyst; in step (5), a portion of the regenerated catalyst is returned to the isolinear fluidized bed reactor for recycling, and another portion of the regenerated catalyst is returned to the riser reactor for recycling; Preferably, at least a portion of the slurry oil component and / or at least a portion of the raffinate oil component is fed into the riser reactor; wherein the feed position of the raffinate oil component is located below the feed position of the heavy oil, and the slurry oil component is fed into the riser reactor via the feed position of the heavy oil.

4. The method according to claim 1, characterized in that: The raw oil includes diesel and heavy oil, the diesel is fed into the isolinear fluidized bed reactor from the lower part of the variable diameter reaction section, and the heavy oil is fed into the isolinear fluidized bed reactor from the middle part of the variable diameter reaction section; 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 isolinear fluidized bed reactor; wherein the feed position of the raffinate oil component is located below the feed position of the diesel, and the slurry oil component is fed from the feed position of the heavy oil.

5. The method according to any one of claims 2 to 4, characterized in that: The diesel is selected from a combination of one or more of straight-run diesel, catalytic cracking diesel and hydrogenated diesel; and / or, The boiling point of the diesel is 180-380°C and the density is less than or equal to 880kg / 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 also includes large pore zeolite, inorganic oxide, clay and modified oxide; The molar ratio of SiO2 to Al2O3 in the medium-pore zeolite and the large-pore zeolite is greater than 10; The mass proportion of the large-pore zeolite in the catalytic cracking catalyst is 20-40%; The inorganic oxide includes aluminum oxide and / or silicon oxide; The mass proportion of the modified oxide in the catalytic cracking catalyst is 1.0 to 5.0%; The modified oxide is selected from 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 to 150 microns.

8. The method according to any one of claims 2 to 4, characterized in that: In step (1), the conditions for the contact reaction between the diesel and the catalytic cracking catalyst in the isolinear fluidized bed reactor include: 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; The diesel is fed into the isolinear fluidized bed reactor under fluidization of a fluidizing medium; The fluidizing medium is atomized water, and the mass ratio of the atomized water to the diesel is (0.10-0.20):1; The oil and gas linear velocity of the variable diameter reaction section is 1.0-2.0 m / s.

9. The method according to claim 3, characterized in that: The conditions for the contact reaction between the heavy oil and the catalytic cracking catalyst in the riser reactor include: 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 heavy oil is (5-10):1; The heavy oil is fed into the riser reactor under 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 and gas linear velocity of the riser reactor is 2.0-12.0 m / s.

10. The method according to claim 1, characterized in that The method further comprises the following steps before step (1): Preheating the feedstock oil to a preheating temperature of 200 to 400° C., preferably 220 to 320° C.; The preheating is performed by heating in a heating furnace, or the feedstock oil is subjected to heat exchange with the product obtained from step (3) and / or step (4); and / or, In step (2), separating the oil mixture comprises the following steps: The oil mixture is subjected to cyclone separation to obtain a first reaction oil gas and a catalyst to be regenerated containing the oil gas; then, the catalyst to be regenerated containing the oil gas is subjected to stripping to obtain the catalyst to be regenerated 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) also yields gaseous alkanes and cycle oil.

11. The method according to claim 1, characterized in that: In step (5): The circulation rate of the regenerated catalyst is 150-200 kg / (m 2 ·Second); The regeneration atmosphere in the regenerator is selected from a combination of one or more of air, oxygen-enriched oxygen and pure oxygen; The regeneration temperature in the regenerator is 600-700°C and the pressure is 0.3-0.6Mpa; The flue gas is optionally returned to the regenerator for recycling after heat exchange, and the temperature of the flue gas returned to the regenerator for recycling is 300-600°C.

12. A system for producing low-carbon olefins and light aromatics by catalytic cracking, characterized in that: The system comprises an isolinear fluidized bed reactor (1), a cyclone separator (IV-1), a settler (IV), an oil-gas separation system (6), an aromatics extraction system (24) and a regenerator (16); The isolinear 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-lift 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; a light hydrocarbon feedstock oil inlet (2) and a first atomizing steam inlet (3) are arranged at the lower part of the reactor reaction section (II), and the first atomizing steam inlet (3) is connected to the light hydrocarbon feedstock oil inlet (2); The oil agent outlet of the reactor outlet section (III) is connected to the oil agent inlet of the cyclone separator (IV-1), the catalyst outlet of the cyclone separator (IV-1) is connected to the inlet of the settler (IV), and the oil and gas outlet of the cyclone separator (IV-1) is connected to the oil and gas inlet of the oil and gas separation system (6); The outlet of the settler (IV) is connected to the catalyst inlet of the catalyst stripping section (IV-2), the catalyst outlet of the catalyst stripping section (IV-2) is connected to the catalyst inlet to be regenerated of the regenerator (16), and the oil and gas outlet of the catalyst stripping section (IV-2) is connected to the oil and gas inlet of the oil and gas separation system (6); 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 connected to the oxygen-containing regeneration gas inlet (17) via a flue gas circulation pipeline (20), the regenerated catalyst outlet of the regenerator (16) is connected to the catalyst inlet of the reactor pre-lift section (I) via a first regeneration agent delivery pipeline (18), and the bottom of the reactor pre-lift section (I) is provided with a first fluidizing medium inlet (4); The oil-gas separation system (6) is provided with a light olefin outlet (7), a gas alkane outlet (8), a gasoline outlet (9), a circulating oil outlet (10) and an oil slurry outlet (11); the gasoline outlet (9) is connected to 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 oil outlet (26); Preferably, the oil and gas outlet of the cyclone separator (IV-1) is connected to the oil and gas inlet of the oil and gas separation system (6) through a reaction oil and gas pipeline (5), and the oil and gas outlet of the catalyst stripping section (IV-2) is connected to the oil and gas inlet of the oil and gas separation system (6) through the reaction oil and gas pipeline (5); Preferably, a stripping medium inlet (14) is provided at the lower portion of the catalyst stripping section (IV-2); Preferably, the catalyst outlet of the catalyst stripping section (IV-2) is connected to the catalyst inlet to be regenerated of the regenerator (16) via a regenerated catalyst delivery pipeline (15); Preferably, a first heavy feedstock oil inlet (12) and a second atomizing steam inlet (13) are provided in the middle of the reaction section (II) of the reactor, and the first heavy feedstock oil inlet (12) is connected to the second atomizing steam inlet (13); Preferably, the oil slurry outlet (11) is connected to the first heavy feedstock oil inlet (12), and / or the reactor reaction section (II) is provided with a raffinate oil recycling inlet connected to the raffinate oil outlet (26), and the raffinate oil recycling inlet is located below the light hydrocarbon feedstock oil inlet (2).

13. The system according to claim 12, characterized in that The system is further provided with a riser reactor (21), wherein the riser reactor (21) is provided with a second heavy feedstock oil inlet (27) and a third atomizing steam inlet (28), wherein the second heavy feedstock oil inlet (27) is connected to the third atomizing steam inlet (28); The regenerated catalyst outlet of the regenerator (16) is connected to the catalyst inlet at the bottom of the riser reactor (21) through a second regeneration agent delivery pipeline (23), and a second fluidizing medium inlet (22) is also provided at the bottom of the riser reactor (21); The oil agent outlet of the riser reactor (21) is connected to the oil agent inlet of the cyclone separator (IV-1); Preferably, the oil slurry outlet (11) is connected to the second heavy feedstock oil inlet (27), and / or the riser reactor (21) is provided with a raffinate oil inlet connected to the raffinate oil outlet (26), and the raffinate oil inlet is located below the second heavy feedstock oil inlet (27).

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