Method for maximum production of propylene through hydrocarbon catalytic cracking and reaction system thereof

Abstract

The invention provides a method for maximum production of propylene through hydrocarbon catalytic cracking and a reaction system thereof, and the method comprises the following steps: in a constant linear velocity fluidized bed reactor, diesel oil and other light petroleum hydrocarbons are contacted with a mesoporous molecular sieve catalyst, and self-heat balance is maintained through regeneration flue gas circulation to realize maximum production of propylene and the like. The method disclosed by the invention can be used for processing heavy oil such as naphtha, wax oil and residual oil while processing light hydrocarbon such as diesel oil, is high in propylene yield, can realize self-heating balance, not only solves the problem of excessive diesel oil production capacity of a refinery plant, but also makes up for the defects of chemical materials.

Description

Technical Field

[0001] The invention relates to the field of catalytic cracking of petroleum hydrocarbons, and in particular to a method and a reaction system for maximally producing propylene 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 gasoline and 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 method for cracking straight-run diesel, that is, 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, while patent CN111718751A discloses a method for preparing a ZSM-5 nanomolecular sieve catalyst modified by a transition metal. As described in the two patents, 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 a moving bed reactor is extended to 78 hours, but the operation is difficult.

[0006] Sinopec's 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 H2+C1-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, in order to meet the growing demand for low-carbon olefins and high-octane clean gasoline and solve the problem of excess diesel, it is necessary to develop a production method for converting diesel into chemical materials such as propylene. Summary of the invention

[0008] The object of the present invention is to provide a method for converting diesel and other light petroleum hydrocarbons into chemical materials such as propylene in maximum amount, with high yield of low-carbon olefins and capable of achieving self-heating balance.

[0009] The first aspect of the present invention provides a method for maximizing the production of propylene by catalytic cracking of hydrocarbons, the method comprising:

[0010] (1) in a constant linear velocity fluidized bed reactor, subjecting a light hydrocarbon feedstock to a first catalytic cracking in the presence of a catalyst to obtain a first oil agent material comprising a first spent catalyst and a first oil gas;

[0011] (2) separating the first oil agent material in a cyclone separator, and the separated oil and gas enter an oil and gas separation system for product separation to obtain products including ethylene, propylene, BTX, and methyl naphthalene oil;

[0012] (3) the separated catalyst to be regenerated enters the regenerator for oxygen-containing regeneration, and the regenerated catalyst is circulated back to the isolinear fluidized bed reactor, wherein part or all of the flue gas after regeneration is circulated back to the regenerator;

[0013] The catalyst comprises a ten-membered ring structure mesoporous molecular sieve with an average pore size of 0.5 to 0.6 nm, and the mesoporous molecular sieve accounts for 30 to 50 weight percent of the total amount of the catalyst.

[0014] According to the method of the first aspect of the present invention, in the isolinear fluidized bed reactor, the reaction temperature is 560-660°C, the reaction pressure is 0.2-0.5MPa, the weight ratio of catalyst to crude oil is 6-12:1, and the reaction time is 4.0-9.0 seconds.

[0015] According to the method of the first aspect of the present invention, the reaction section of the isolinear fluidized bed reactor is a variable diameter whose diameter gradually increases from bottom to top;

[0016] Preferably, in the isolinear fluidized bed reactor, the oil and gas linear velocity is 1.0 to 2.0 m / s, and the catalyst circulation rate is 150 to 200 kg / m 2 ·Second).

[0017] According to the method of the first aspect of the present invention, the atmosphere for oxygen-containing regeneration is an oxygen-rich and / or pure oxygen atmosphere;

[0018] The temperature of the regenerator is 620-760°C and the pressure is 0.3-0.6MPa; and / or

[0019] The flue gas temperature of the circulating regenerator is 420-560°C.

[0020] According to the method of the first aspect of the present invention, the catalyst comprises a mesoporous molecular sieve, an optional mesoporous molecular sieve, an optional inorganic oxide and an optional clay, wherein the mesoporous molecular sieve is a twelve-membered ring structure molecular sieve with an average pore size of 0.55-0.75 nm;

[0021] Preferably, the average particle size of the catalyst is 40 to 150 microns;

[0022] More preferably, the catalyst is modified with one or more metal and / or non-metal oxides selected from Group IA, Group IIA, Group VA, Group VIA, Group VIIA, Group IB, Group IIB or transition metal elements, and the oxide accounts for 0.5 to 5.0 weight % of the total catalyst.

[0023] According to the method of the first aspect of the present invention, the light hydrocarbon feedstock oil is diesel;

[0024] Preferably, the diesel comprises straight-run diesel, catalytic cracking diesel and / or hydrogenated diesel; the boiling point of the diesel is 180-380°C, and the density is not more than 860kg / m 3 .

[0025] According to the method of the first aspect of the present invention, the light hydrocarbon feedstock oil is preheated before entering the reactor, and the preheating temperature is 200 to 400° C., preferably 240 to 340° C.; and / or

[0026] The fluidizing medium of the isolinear fluidized bed reactor is water vapor. Preferably, the mass ratio of the water vapor to the feedstock oil is 0.15-0.25.

[0027] According to the method of the first aspect of the present invention, the method further comprises feeding heavy oil into the isolinear fluidized bed reactor, wherein the feeding position of the heavy oil is located above the feeding position of the light hydrocarbon feedstock oil;

[0028] The heavy oil is wax oil, residual oil and / or oil slurry separated by the oil-gas separation system in step (2).

[0029] According to the method of the first aspect of the present invention, the method further comprises: subjecting the heavy oil and / or the oil slurry separated by the oil-gas separation system to a second catalytic cracking reaction in a second reactor to obtain a second oil agent material containing second oil and gas and a second spent catalyst;

[0030] Separating the second mixed material in a cyclone separator;

[0031] Preferably, the second reactor is a riser reactor or a variable diameter riser bed reactor.

[0032] A second aspect of the present invention provides a reaction system for catalytic cracking of hydrocarbons to produce propylene in maximum quantity, the reaction system comprising:

[0033] The isolinear fluidized bed reaction system comprises:

[0034] - isolinear fluidized bed reactor,

[0035] - a cyclone separator, and

[0036] - stripper,

[0037] The cyclone separator is arranged at the top of the isolinear fluidized bed reactor and is connected to the stripper, so that the spent catalyst separated by the cyclone separator is stripped in the stripper;

[0038] Regenerator,

[0039] The stripper is connected to the regenerator, so that the catalyst to be regenerated after being stripped by the stripper enters the regenerator for regeneration; the regenerator is also connected to the constant linear velocity fluidized bed reactor, so that the regenerated catalyst after being regenerated by the regenerator is circulated back to the constant linear velocity fluidized bed reactor; the regenerator also includes a flue gas circulation system, and part or all of the regenerated flue gas is circulated back to the regenerator;

[0040] An oil-gas separation system, the oil-gas separation system being in communication with the oil-gas outlet of the isolinear fluidized bed reactor;

[0041] Preferably, the isolinear fluidized bed reactor is provided with a light hydrocarbon feedstock oil inlet and a heavy oil inlet, and the heavy oil inlet is provided above the light hydrocarbon feedstock oil inlet;

[0042] More preferably, the heavy oil inlet is communicated with the oil slurry outlet of the oil-gas separation system.

[0043] According to the reaction system of the second aspect of the present invention, the reaction system further comprises a second reactor, the second reactor is a heavy oil catalytic cracking reactor, the outlet of the second reactor is connected to the outlet section of the isolinear fluidized bed reactor, and the second mixed material containing the second oil gas and the second spent catalyst obtained after the second catalytic cracking reaction in the second reactor is separated in a cyclone separator;

[0044] Preferably, the second reactor is a riser reactor or a variable diameter riser bed reactor;

[0045] More preferably, the inlet of the second reactor is communicated with the oil slurry outlet of the oil-gas separation system.

[0046] Compared with the prior art, the present invention has the following technical effects:

[0047] (1) The present invention uses a constant linear velocity fluidized bed reactor, which does not require external heating and can produce continuously compared with fixed bed and moving bed reactors; compared with conventional riser reactors, the oil agent is fully contacted and is more suitable for volume expansion light hydrocarbon catalytic cracking.

[0048] (2) Regeneration in an oxygen-enriched and / or pure oxygen atmosphere, compared with conventional air regeneration, has less heat to heat up the air, higher charring intensity, and higher regeneration temperature, which can maintain a higher regeneration agent temperature.

[0049] (3) After regeneration, part or all of the high-temperature flue gas is returned to the regenerator, which not only fully utilizes the oxygen in the flue gas, but also solves the problem of the flue gas carrying heat out of the regeneration system, and reduces the emission of waste gases such as carbon dioxide, thus significantly saving energy and reducing emissions.

[0050] (4) The high-precision separation system is used to separate the liquid products into light gasoline fraction with an initial boiling point of -60°C, BTX fraction of 60-150°C, heavy aromatic fraction of 150-240°C, methyl naphthalene oil fraction of 240-340°C and slurry oil of >340°C, which can better meet the demand for producing more chemical materials by catalytic cracking of light hydrocarbons. Unlike the conventional catalytic cracking separation system, the liquid products are cut into gasoline fraction (initial boiling point -200°C), diesel fraction (200-360°C) and slurry oil fraction (>360°C). BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 It is a schematic diagram of a process flow of an embodiment of the present invention, used to illustrate the process flow of isolinear fluidized bed catalytic cracking of light hydrocarbon feedstock oil.

[0052] Figure 2 It is a schematic diagram of a process flow of an embodiment of the present invention, used to illustrate the catalytic cracking process of coupling a light hydrocarbon feedstock isolinear fluidized bed with a heavy feedstock riser.

[0053] Description of reference numerals:

[0054] I. Reactor pre-lifting section; II. Reactor reaction section; III. Reactor outlet section; IV. Settler; V. Cyclone separator; VI. Catalyst settling section; 1. Constant linear velocity fluidized bed reactor; 2. Light hydrocarbon feedstock oil; 3. Atomizing steam I; 4. Fluidizing medium I; 5. Reaction oil and gas pipeline; 6. Oil and gas separation system; 7. Ethylene; 8. Propylene; 9. H2+C1-C4 alkane; 10. C4 olefin; 11. Light gasoline fraction ; 12. BTX fraction; 13. Heavy aromatic fraction; 14. Methylnaphthalene oil fraction; 15. Oil slurry; 16. Heavy crude oil; 17. Atomizing steam II; 18. Stripping medium; 19. Regenerated agent delivery pipeline; 20. Regenerator; 21. Oxygen-containing regeneration gas; 22. Regeneration agent delivery pipeline I; 23. Flue gas; 24. Flue gas circulation system; 25. Riser reactor; 26. Fluidizing medium II; 27. Regeneration agent delivery pipeline II. DETAILED DESCRIPTION

[0055] 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.

[0056] 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.

[0057] 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.

[0058] Before describing the technical solution of the present invention, the terms used in this article are defined as follows:

[0059] The term "BTX" refers to: light aromatics, a mixture of benzene, toluene and xylenes.

[0060] The present invention provides a method for maximizing the production of propylene by catalytic cracking of hydrocarbons, comprising:

[0061] (1) in a constant linear velocity fluidized bed reactor, subjecting a light hydrocarbon feedstock to a first catalytic cracking in the presence of a catalyst to obtain a first oil agent material comprising a first spent catalyst and a first oil gas;

[0062] (2) separating the first oil agent material in a cyclone separator, and the separated oil and gas enter an oil and gas separation system for product separation to obtain products including ethylene, propylene, BTX, and methyl naphthalene oil;

[0063] (3) the separated catalyst to be regenerated enters the regenerator for oxygen-containing regeneration, and the regenerated catalyst is circulated back to the isolinear fluidized bed reactor, wherein part or all of the flue gas after regeneration is circulated back to the regenerator;

[0064] The catalyst comprises a ten-membered ring structure mesoporous molecular sieve with an average pore size of 0.5 to 0.6 nm, and the mesoporous molecular sieve accounts for 30 to 50 weight percent of the total amount of the catalyst.

[0065] The constant linear velocity fluidized bed reactor of the present invention is a constant linear velocity fluidized bed reactor, which means that the catalytic cracking reaction oil and gas maintain a relatively uniform linear velocity in the fluidized bed reactor. Because the catalytic cracking reaction is a reaction of rapid volume expansion, the reaction section of the constant linear velocity fluidized bed reactor is a variable diameter with a diameter gradually enlarged from bottom to top; preferably, in the constant linear velocity fluidized bed reactor, the oil and gas linear velocity is 1.0-2.0 m / s, and the catalyst circulation rate is 150-200 kg / (m 2 · seconds). Compared with a common fluidized bed with 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.

[0066] The inventors have found through years of research that: (1) Diesel catalytic cracking is different from heavy oil catalytic cracking in that small molecules are difficult to crack, thus requiring a higher reaction severity; (2) The isolinear fluidized bed reactor is adapted to the volume expansion reaction system and reduces the dry gas and coke yields under the high reaction severity of diesel; (3) Diesel catalytic cracking produces low coke, and conventional heavy oil regeneration technology is difficult to maintain the heat required for its own reaction through self-heating balance; (4) The traditional catalytic cracking oil-gas separation system cuts oil products into gasoline fraction (initial distillation point -200°C), diesel fraction (200-360°C), and oil slurry fraction (>360°C), which cannot meet the demand for producing more chemical materials by catalytic cracking of light hydrocarbons.

[0067] The invention not only solves the heat balance problem of catalytic cracking of light hydrocarbons itself, but also realizes a higher conversion rate of catalytic cracking of light hydrocarbons at a higher reaction temperature by using a constant linear velocity fluidized bed reactor and oxygen-enriched and / or pure oxygen regeneration and returning part and / or all of the high-temperature flue gas after regeneration to the regenerator; and the invention also uses a high-precision separation system to accurately separate liquid products to obtain products such as a light gasoline fraction with an initial boiling point of -60°C, a BTX fraction of 60-150°C, a heavy aromatic fraction of 150-240°C, a methyl naphthalene oil fraction of 240-340°C, and an oil slurry of more than 340°C, and recycles the light gasoline fraction, the light aromatic raffinate oil, and the heavy aromatic fraction to produce propylene and BTX in maximum quantity, and further supplements the heat required by the reactor by recycles the oil slurry.

[0068] Based on the above findings, the present invention provides a catalytic cracking method for converting diesel into propylene using a variable diameter constant linear velocity fluidized bed reactor, in which diesel is contacted with a high-activity catalyst to carry out a high-temperature, large catalyst-to-oil ratio catalytic cracking reaction; the coked and deactivated catalyst is regenerated in an oxygen-rich and / or pure oxygen atmosphere and part and / or all of the regenerated high-temperature flue gas is returned to the regenerator; thereby achieving the self-thermal balance of the regeneration of the light hydrocarbon catalytic cracking reaction, achieving a higher conversion rate at a higher reaction temperature, and achieving efficient continuous production.

[0069] According to the method of the present invention, the reaction oil and gas are separated by a high-precision separation system, and the gas product separation obtains ethylene, propylene, C4 olefins and H2+C1-C4 alkanes, and the liquid product separation obtains light gasoline fraction with an initial boiling point of -60°C, 60-150°C BTX fraction, 150-240°C heavy aromatic fraction, 240-340°C methyl naphthalene oil fraction and >340°C slurry oil and other products, and the BTX fraction is hydrogenated and extracted to obtain BTX and light aromatic raffinate oil; preferably, the C4 olefins, light gasoline fraction, light aromatic raffinate oil, heavy aromatic fraction and >340°C slurry oil obtained by high-precision separation are returned to the reactor for refining.

[0070] The present invention uses a constant linear velocity fluidized bed reactor, which does not require external heating and can produce continuously compared with fixed bed and moving bed reactors; compared with conventional riser reactors, the oil agent is fully contacted and is more suitable for volume expansion light hydrocarbon catalytic cracking.

[0071] The high-temperature flue gas after regeneration is partially or completely returned to the regenerator, which not only fully utilizes the oxygen in the flue gas, but also maintains a high regeneration temperature of the regenerator and a high regeneration agent temperature. It not only solves the problem of flue gas carrying heat out of the reaction regeneration system, but also reduces the emission of waste gas such as carbon dioxide, thus significantly saving energy and reducing emissions.

[0072] The reactor and the regenerator can be arranged in parallel or overlapped, and the fluidized bed and the settler can be internal or external; the catalyst is lifted by media such as air and / or water vapor so that it circulates between the reactor and the regenerator.

[0073] In one embodiment, in the isolinear fluidized bed reactor, the reaction temperature is 560-660° C., the reaction pressure is 0.2-0.5 MPa, the weight ratio of catalyst to feedstock oil is 6-12:1, and the reaction time is 4.0-9.0 seconds.

[0074] The catalyst in the reactor may be in an upward flow or a downward flow; preferably, the catalyst is in an upward flow.

[0075] In one embodiment, the reaction section of the isolinear fluidized bed reactor is a variable diameter whose diameter gradually increases from bottom to top;

[0076] Preferably, in the isolinear fluidized bed reactor, the oil and gas linear velocity is 1.0 to 2.0 m / s, and the catalyst circulation rate is 150 to 200 kg / m 2 ·Second).

[0077] The catalyst in the reactor may be in an upward flow or a downward flow; preferably, the catalyst is in an upward flow.

[0078] In one embodiment, the oxygen-containing regeneration atmosphere is an oxygen-rich and / or pure oxygen atmosphere;

[0079] The temperature of the regenerator is 620-760°C and the pressure is 0.3-0.6MPa; and / or

[0080] The flue gas temperature of the circulating regenerator is 420-560°C.

[0081] In one embodiment, the catalyst comprises a mesoporous molecular sieve, an optional mesoporous molecular sieve, an optional inorganic oxide, and an optional clay, wherein the mesoporous molecular sieve is a twelve-membered ring structure molecular sieve with an average pore size of 0.55-0.75 nm;

[0082] Preferably, the average particle size of the catalyst is 40 to 150 microns;

[0083] More preferably, the catalyst is modified with one or more metal and / or non-metal oxides selected from Group IA, Group IIA, Group VA, Group VIA, Group VIIA, Group IB, Group IIB or transition metal elements, and the oxide accounts for 0.5 to 5.0 weight % of the total catalyst.

[0084] In a specific embodiment, the mesoporous molecular sieve is a ten-membered ring structure molecular sieve with an average pore size of 0.5-0.6 nm, selected from one or more of ZSM-5 molecular sieve, ZSM-11 molecular sieve, ZSM-12 molecular sieve, ZSM-23 molecular sieve, ZSM-35 molecular sieve, ZSM-38 molecular sieve, ZSM-48 molecular sieve, and ZRP molecular sieve; the mesoporous molecular sieve is a twelve-membered ring structure molecular sieve with an average pore size of 0.55-0.75 nm, such as BETA molecular sieve, MCM-22 molecular sieve, etc., selected from one or more of BETA molecular sieve, MCM-22 molecular sieve, and NU-87 molecular sieve; the inorganic oxide is a heat-resistant inorganic oxide, preferably a binder such as aluminum oxide and silicon oxide.

[0085] In a specific embodiment, the catalyst is a composite composed of a ZSM-5 series mesoporous molecular sieve with an MFI structure, a Beta mesoporous molecular sieve, a binder such as alumina, silica, and an optional natural porous carrier material such as clay, wherein the mesoporous molecular sieve accounts for 30 to 50% by weight of the total catalyst, and the mesoporous molecular sieve accounts for 10 to 20% by weight of the total catalyst.

[0086] In one embodiment, the light hydrocarbon feedstock oil is diesel;

[0087] Preferably, the diesel comprises straight-run diesel, catalytic cracking diesel and / or hydrogenated diesel; the boiling point of the diesel is 180-380°C, and the density is not more than 860kg / m 3 .

[0088] In one embodiment, the light hydrocarbon feedstock oil is preheated before entering the reactor, and the preheating temperature is 200-400° C., preferably 240-340° C.; and / or

[0089] The fluidizing medium of the isolinear fluidized bed reactor is water vapor. Preferably, the mass ratio of the water vapor to the feedstock oil is 0.15-0.25.

[0090] The raw materials can be preheated by heating in a heating furnace or by exchanging heat with the product to the preheating temperature.

[0091] In one embodiment, the method further comprises feeding heavy oil into the isolinear fluidized bed reactor, wherein the feeding position of the heavy oil is located above the feeding position of the light hydrocarbon feedstock oil;

[0092] The heavy oil is wax oil, residual oil and / or oil slurry separated by the oil-gas separation system in step (2).

[0093] In one embodiment, the method further comprises: subjecting the heavy oil and / or the oil slurry separated by the oil-gas separation system to a second catalytic cracking reaction in a second reactor to obtain a second mixed material comprising second oil and gas and a second spent catalyst;

[0094] Separating the second mixed material in a cyclone separator;

[0095] Preferably, the second reactor is a riser reactor or a variable diameter riser bed reactor.

[0096] The present invention also provides a reaction system for catalytic cracking of hydrocarbons to produce propylene in maximum quantity, comprising:

[0097] The isolinear fluidized bed reaction system comprises:

[0098] - isolinear fluidized bed reactor,

[0099] - a cyclone separator, and

[0100] - stripper,

[0101] The cyclone separator is arranged at the top of the isolinear fluidized bed reactor and is connected to the stripper, so that the spent catalyst separated by the cyclone separator is stripped in the stripper;

[0102] Regenerator,

[0103] The stripper is connected to the regenerator, so that the catalyst to be regenerated after being stripped by the stripper enters the regenerator for regeneration; the regenerator is also connected to the constant linear velocity fluidized bed reactor, so that the regenerated catalyst after being regenerated by the regenerator is circulated back to the constant linear velocity fluidized bed reactor; the regenerator also includes a flue gas circulation system, and part or all of the regenerated flue gas is circulated back to the regenerator;

[0104] A separation system, the separation system being in communication with the oil and gas outlet of the isolinear fluidized bed reactor;

[0105] Preferably, the isolinear fluidized bed reactor is provided with a light hydrocarbon feedstock oil inlet and a heavy oil inlet, and the heavy oil inlet is provided above the light hydrocarbon feedstock oil inlet;

[0106] More preferably, the heavy oil inlet is communicated with the oil slurry outlet of the oil-gas separation system.

[0107] In one embodiment, the reaction system further comprises a second reactor, the second reactor is a heavy oil catalytic cracking reactor, the outlet of the second reactor is connected to the outlet section of the isolinear fluidized bed reactor, and the second mixed material containing the second oil gas and the second spent catalyst obtained after the second catalytic cracking reaction in the second reactor is separated in a cyclone separator;

[0108] Preferably, the second reactor is a riser reactor or a variable diameter riser bed reactor;

[0109] More preferably, the inlet of the second reactor is communicated with the oil slurry outlet of the oil-gas separation system.

[0110] In one embodiment, the reaction section of the isolinear fluidized bed reactor has a variable diameter with the diameter gradually increasing from bottom to top.

[0111] A specific embodiment of the present invention is as follows Figure 1 As shown, in this embodiment, an upward variable diameter constant linear velocity fluidized bed reactor 1 is used, and the light hydrocarbon feedstock oil 2 enters the reactor by bottom feeding to contact the regeneration agent for catalytic cracking reaction, and the spent catalyst is separated from the oil and gas after the reaction and then regenerated, and the flue gas after regeneration is partially circulated back to the regenerator. The process flow is as follows:

[0112] The light hydrocarbon feedstock oil 2 is atomized by atomizing steam I3 and enters the bottom of the variable diameter reactor reaction section II in the constant linear velocity fluidized bed reactor 1, and the hot regenerated agent is introduced into the pre-lifting section I of the fluidized bed reactor through the regenerated agent delivery pipeline 18, and enters the reactor reaction section II upward under the fluidization of the fluidizing medium I4, and the light hydrocarbon feedstock oil 2 contacts the hot regenerated agent for catalytic cracking reaction; after the reaction, the oil gas and the catalyst enter the cyclone separator V through the reactor outlet section III for oil-agent separation, and the separated catalyst settles to the reactor stripping section, and enters the regenerator 20 through the regenerated agent delivery pipeline 19 after stripping by the stripping medium 18; the regenerated agent is regenerated in the oxygen-containing atmosphere in the regenerator 20, The oxygen-containing regeneration gas 21 includes air, oxygen, etc., and the regeneration temperature is 620-720°C. The regenerated catalyst is recycled; part of the regenerated flue gas 23 is recycled back to the regenerator 20 through the flue gas circulation system 24; the separated reaction oil and gas enter the high-precision oil and gas separation system 6 through the reaction oil and gas pipeline 5, and the products ethylene 7, propylene 8, H2+C1-C4 alkanes 9, C4 olefins 10, light gasoline fraction 11, BTX fraction 12, heavy aromatic fraction 13, methyl naphthalene oil fraction 14 and oil slurry 15 are separated; and the C4 olefins 10, light gasoline fraction 11 and heavy aromatic fraction 13 as well as oil slurry 15 can be recycled and / or not recycled according to production needs. In order to meet the demand for more chemical materials, C4 olefins 10, light gasoline 11 and heavy aromatic fractions 13 are preferably recycled, which can be mixed with light hydrocarbon feedstock 2 and then enter the isolinear fluidized bed reactor 1, and further preferably enter the bottom of the variable diameter reactor reaction section II, that is, feed at the lower part of the light hydrocarbon feedstock nozzle. In order to meet the need for self-heating balance of the device, oil slurry recycling is preferred, that is, oil slurry and / or heavy feedstock 16 are atomized by atomizing steam II17 and then enter the reactor, preferably enter the middle of the variable diameter reactor reaction section II, that is, feed at the upper part of the light hydrocarbon feedstock nozzle.

[0113] Figure 2 This is a process flow diagram of another embodiment of the present invention. The light hydrocarbon feedstock uses a variable diameter constant linear velocity fluidized bed reactor 1 as in Example 1. The difference is that the oil slurry is recycled and / or the heavy feedstock 12 enters a conventional riser reactor 25. The two reactors can each use a separate settler or share a settler. In this embodiment, the two reactors use a single settler. The process flow is as follows:

[0114] The light hydrocarbon feedstock oil 2 is atomized by atomizing steam I3 and enters the bottom of the variable diameter reaction section II in the isolinear fluidized bed reactor 1, while the hot regenerated agent is introduced into the pre-lift section I of the fluidized bed reactor through the regenerated agent delivery pipeline 18, and enters the reactor reaction section II under the fluidization of the fluidized medium 4, and the light hydrocarbon feedstock oil 2 contacts the hot regenerated agent for catalytic cracking reaction; the heavy feedstock oil 16 is atomized by atomizing steam II17 and enters the lower part of the riser reactor 25, while the hot regenerated agent is introduced into the bottom of the riser reactor 25 through the regenerated agent delivery pipeline II27, and ascends under the fluidization of the fluidized medium II26, and the heavy feedstock oil 16 contacts the hot regenerated agent for catalytic cracking reaction; after the reaction of the light hydrocarbon feedstock oil 2 and the heavy feedstock oil 16, the oil and gas both enter the cyclone separator V for oil-agent separation; after the reaction, the oil and gas and the catalyst enter the cyclone separator V through the reactor outlet section III for oil separation. The catalyst is separated from the catalyst, and the separated catalyst settles to the stripping section of the reactor, and enters the regenerator 20 through the regenerator conveying pipeline 19 after being stripped by the stripping medium 18; the regenerator is regenerated in the oxygen-containing atmosphere in the regenerator 20, and the oxygen-containing regeneration gas 21 includes air, oxygen, etc., and the regeneration temperature is 620-720°C, and the regenerated catalyst is recycled; part of the regenerated flue gas 23 is recycled back to the regenerator 20 through the flue gas circulation system 24; the separated reaction oil and gas enters the high-precision oil and gas separation system 6 through the reaction oil and gas pipeline 5, and the products ethylene 7, propylene 8, H2+C1-C4 alkanes 9, C4 olefins 10, light gasoline fraction 11, BTX fraction 12, heavy aromatic fraction 13, methyl naphthalene oil fraction 14 and oil slurry 15 are separated; and the C4 olefins 10, light gasoline fraction 11 and heavy aromatic fraction 13 as well as oil slurry 15 can be recycled and / or not recycled according to production needs. The oil slurry 15 is recycled and can enter the middle of the variable diameter reaction section II of the constant linear velocity fluidized bed reactor 1, and is preferably selected and / or the heavy crude oil 16 is atomized by the atomizing steam II17 and enters the riser reactor 25. In order to meet the demand for more chemical materials, C4 olefins 10, light gasoline 11 and heavy aromatic fractions 13 are preferably recycled, and the recycled C4 olefins 10, light gasoline 11 and heavy aromatic fractions 13 can enter the constant linear velocity fluidized bed reactor 1, and are preferably selected to enter the bottom of the riser reactor 25, that is, the heavy crude oil 16 is fed at the bottom of the nozzle for catalytic cracking reaction.

[0115] The present invention is further described in detail by way of examples. The raw materials used in the examples can be obtained through commercial sources.

[0116] The following examples will further illustrate the method, but are not intended to limit the method.

[0117] The light hydrocarbon feedstock used in the examples is straight-run diesel from a refinery, and the heavy feedstock oil is hydrogenated wax oil after hydrogenation refining of wax oil from a refinery. The properties of the two are shown in Table 1.

[0118] The catalysts used in the examples are the same, and their preparation methods are briefly described as follows:

[0119] 1) 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 its pH to 2-4 with hydrochloric acid, stir evenly, stand and age at 60-70°C for 1 hour, keep the pH at 2-4, reduce the temperature to below 60°C, add 10.4Kg of aluminum sol (product of Sinopec Catalyst Qilu Branch, Al2O3 content is 21.7m%), stir for 40 minutes, and obtain a mixed slurry.

[0120] 2) Add the mesoporous ZRP-2 molecular sieve with MFI structure (industrial product of Sinopec Catalyst Qilu Branch, SiO2 / Al2O3=39, phosphorus content P2O5=2.1% by weight, iron content Fe2O3=3.1% by weight, dry basis 18.5kg) and β molecular sieve (industrial product of Sinopec Catalyst Qilu Branch, SiO2 / Al2O3=52, dry basis 6.3kg) to the mixed slurry obtained in step 1), stir evenly, put it in a bonding machine, add appropriate amount of water, stir well, place it in the air for 4 hours, and spray dry it into shape.

[0121] 3) The catalyst obtained by spray drying in step 2) was dried in a drying oven at 120°C for 3 hours, and then washed with diammonium phosphate solution (phosphorus content of 1m%) to remove free Na + The catalyst was dried again at 120°C for 3 hours and was named CAT-3.

[0122] The composition of the catalyst is 37.6 wt% of mesoporous ZRP-2 molecular sieve, 12.8 wt% of mesoporous β molecular sieve, 17.6 wt% of pseudo-boehmite, 4.6 wt% of aluminum sol and 27.4% of kaolin. Its properties are listed in Table 2.

[0123] Example 1

[0124] This embodiment follows Figure 1The process was tested, using the straight-run diesel A in Table 1 as the raw material, and the test was carried out on an isolinear fluidized bed reactor, using a CAT-3 catalyst. The raw oil A was preheated at 340°C and entered the bottom of the reaction section of the isolinear fluidized bed reactor. At a reaction pressure of 0.40MPa, water vapor was used as the fluidizing medium, and the mass ratio of atomized steam to raw oil was 0.20. As the fluidizing medium flowed from bottom to top, the catalytic cracking reaction was carried out under the conditions of a reaction temperature (based on the reactor outlet, the same below) of 640°C, a weight ratio of catalyst to raw oil of 7.5, and a reaction time of 5.0 seconds; after the reaction, the oil agent was separated, and the separated reaction oil and gas were separated by a high-precision oil and gas separation system to obtain the products H2, ethylene, Propylene, C1-C4 alkanes, BTX, methyl naphthalene oil and C4 olefins, light gasoline fractions, heavy aromatic fractions and oil slurry, C4 olefins, light gasoline fractions, heavy aromatic fractions and oil slurry recycling; the spent catalyst after oil separation is stripped by steam to remove the oil and gas adsorbed inside, and then sent to the regenerator, using oxygen as the regeneration gas, and regenerating it at a regeneration temperature of 660-690℃; the regenerated regenerated agent is recycled, 50% of the flue gas after regeneration is recycled, the circulating flue gas temperature is 500℃, and the regeneration dense phase temperature is maintained at 690℃. The operating conditions and product distribution are listed in Table 3.

[0125] As can be seen from Table 3, in Example 1, the catalytic cracking reaction of straight-run diesel in a constant linear velocity fluidized bed reactor has a propylene yield of 27.63% by weight, an ethylene yield of 10.74% by weight, a light aromatics (benzene + toluene + xylene) yield of 12.60% by weight, and a coke yield of 6.35% by weight.

[0126] Comparative Example 1

[0127] 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.

[0128] As can be seen from Table 3, compared with Comparative Example 1 (riser reactor), Example 1 (constant linear velocity fluidized bed reactor) has a propylene yield increased by 9.11 percentage points, an ethylene yield increased by 3.23 percentage points, a light aromatics (benzene + toluene + xylene) yield increased by 1.18 percentage points, and a coke yield decreased by 1.63 percentage points.

[0129] Example 2

[0130] This embodiment follows Figure 2The process was tested, using 70% straight-run diesel A and 30% hydrogenated wax oil B in Table 1 as raw materials. The two were tested in an isolinear fluidized bed reactor and a riser reactor, respectively, using a CAT-3 catalyst. The crude oil A was preheated at 300°C and entered the bottom of the reaction section of the isolinear fluidized bed reactor, and the crude oil B was preheated at 300°C and entered the bottom of the conventional riser reactor; both were at a reaction pressure of 0.30MPa, with water vapor as the fluidizing medium, and a mass ratio of atomized steam to crude oil of 0.15. As the fluidizing medium flows from bottom to top in different reactors, catalytic cracking reactions are carried out under the conditions of a reaction temperature (based on the reactor outlet) of 600°C, a weight ratio of catalyst to crude oil of 9.0, and a reaction time of 8.0 seconds; the oil gas and catalyst after the reaction of crude oil B in the riser reactor are merged into the isolinear fluidized bed reactor, and the oil agent is separated together with the oil agent after the reaction of crude oil A; after the oil agent is separated The reaction oil and gas after separation are separated by a high-precision oil and gas separation system to obtain products H2, ethylene, propylene, C1-C4 alkanes, BTX, methyl naphthalene oil and C4 olefins, light gasoline fractions, heavy aromatic fractions and oil slurry, and C4 olefins, light gasoline fractions, heavy aromatic fractions and oil slurry are recycled; the catalyst to be regenerated after oil separation is stripped by steam to remove the oil and gas adsorbed inside it and then sent to the regenerator, using 20% ​​oxygen and 80% air enriched air as regeneration gas, and regenerating it at a regeneration temperature of 650-670℃ in contact with the catalyst to be regenerated; the regenerated regenerated agent is recycled, and the flue gas after regeneration is partially recycled, the circulating flue gas temperature is 450℃, and the regeneration dense phase temperature is maintained at 670℃. The operating conditions and product distribution are listed in Table 3.

[0131] As can be seen from Table 3, in Example 2, the hydrogenated diesel was subjected to catalytic cracking reaction in a constant linear velocity fluidized bed reactor and the cracked tail oil was subjected to catalytic cracking reaction in a riser reactor at the same time, and the propylene yield was 25.41% by weight, the ethylene yield was 20.57% by weight, the light aromatics (benzene + toluene + xylene) yield was 15.39% by weight, and the coke yield was 7.84% by weight.

[0132] Comparative Example 2

[0133] The catalytic cracking reaction was carried out by using the same feedstock oil, catalyst and process conditions as in Example 1, except that: 1) both the hydrogenated diesel A and the cracked tail oil B in Comparative Example 2 used a riser reactor; 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.

[0134] As can be seen from Table 3, compared with Comparative Example 2 (riser reactor), Example 2 (constant linear velocity fluidized bed reactor) has a propylene yield that is increased by 4.84 percentage points, an ethylene yield that is increased by 2.25 percentage points, a light aromatics (benzene + toluene + xylene) yield that is increased by 1.37 percentage points, and a coke yield that is reduced by 1.24 percentage points.

[0135] 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.

[0136] Table 1

[0137] Raw oil name Straight run diesel Heavy crude oil Crude oil number A B <![CDATA[Density at 20 °C, kg / m 3 > 840.4 898.2 Sulfur content, weight % 0.938 0.17 Nitrogen content, weight % 0.0085 0.07 Four components Saturated hydrocarbons, weight % 75.7 56.5 Aromatics, weight % 24.3 43.5 ASTM D86 distillation range, ℃ Initial distillation point 194 358 10％ 217 389 50％ 283 430 90％ 340 515 Final distillation point 364 562

[0138] Table 2

[0139]

[0140]

[0141] Table 3

[0142]

Claims

1. A method for maximizing the production of propylene by catalytic cracking of hydrocarbons, characterized in that: The method comprises: (1) in a constant linear velocity fluidized bed reactor, subjecting a light hydrocarbon feedstock to a first catalytic cracking in the presence of a catalyst to obtain a first oil agent material comprising a first spent catalyst and a first oil gas; (2) separating the first oil agent material in a cyclone separator, and the separated oil and gas enter an oil and gas separation system for product separation to obtain products including ethylene, propylene, BTX, and methyl naphthalene oil; (3) the separated catalyst to be regenerated enters the regenerator for oxygen-containing regeneration, and the regenerated catalyst is circulated back to the isolinear fluidized bed reactor, wherein part or all of the flue gas after regeneration is circulated back to the regenerator; The catalyst comprises a ten-membered ring structure mesoporous molecular sieve with an average pore size of 0.5 to 0.6 nm, and the mesoporous molecular sieve accounts for 30 to 50 weight percent of the total amount of the catalyst.

2. The method according to claim 1, characterized in that In the isolinear fluidized bed reactor, the reaction temperature is 560-660° C., the reaction pressure is 0.2-0.5 MPa, the weight ratio of catalyst to crude oil is 6-12:1, and the reaction time is 4.0-9.0 seconds.

3. The method according to claim 1, characterized in that The reaction section of the isolinear fluidized bed reactor has a variable diameter with the diameter gradually increasing from bottom to top; Preferably, in the isolinear fluidized bed reactor, the oil and gas linear velocity is 1.0 to 2.0 m / s, and the catalyst circulation rate is 150 to 200 kg / m 2 ·Second).

4. The method according to claim 1, characterized in that: The oxygen-containing regeneration atmosphere is an oxygen-rich and / or pure oxygen atmosphere; The temperature of the regenerator is 620-760°C and the pressure is 0.3-0.6MPa; and / or The flue gas temperature of the circulating regenerator is 420-560°C.

5. The method according to claim 1, characterized in that The catalyst comprises a mesoporous molecular sieve, an optional mesoporous molecular sieve, an optional inorganic oxide and an optional clay, wherein the mesoporous molecular sieve is a twelve-membered ring structure molecular sieve with an average pore size of 0.55-0.75 nm; Preferably, the average particle size of the catalyst is 40 to 150 microns; More preferably, the catalyst is modified with one or more metal and / or non-metal oxides selected from Group IA, Group IIA, Group VA, Group VIA, Group VIIA, Group IB, Group IIB or transition metal elements, and the oxide accounts for 0.5 to 5.0 weight % of the total catalyst.

6. The method according to claim 1, characterized in that The light hydrocarbon feedstock oil is diesel; Preferably, the diesel comprises straight-run diesel, catalytic cracking diesel and / or hydrogenated diesel; the boiling point of the diesel is 180-380°C, and the density is not more than 860kg / m 3 .

7. The method according to claim 1, characterized in that The light hydrocarbon feedstock oil is preheated before entering the reactor, the preheating temperature is 200-400° C., preferably 240-340° C.; and / or The fluidizing medium of the isolinear fluidized bed reactor is water vapor. Preferably, the mass ratio of the water vapor to the feedstock oil is 0.15-0.

25.

8. The method according to claim 1, characterized in that: The method further comprises feeding heavy oil into the isolinear fluidized bed reactor, wherein the feeding position of the heavy oil is located above the feeding position of the light hydrocarbon feedstock oil; The heavy oil is wax oil, residual oil and / or oil slurry separated by the oil-gas separation system in step (2).

9. The method according to claim 1, characterized in that: The method further comprises: subjecting the heavy oil and / or the oil slurry separated by the oil-gas separation system to a second catalytic cracking reaction in a second reactor to obtain a second oil agent material containing second oil and gas and a second spent catalyst; Separating the second mixed material in a cyclone separator; Preferably, the second reactor is a riser reactor or a variable diameter riser bed reactor.

10. A reaction system for catalytic cracking of hydrocarbons to produce propylene in maximum quantity, characterized in that: The reaction system comprises: The isolinear fluidized bed reaction system comprises: - isolinear fluidized bed reactor, - a cyclone separator, and - stripper, The cyclone separator is arranged at the top of the isolinear fluidized bed reactor and is connected to the stripper, so that the spent catalyst separated by the cyclone separator is stripped in the stripper; Regenerator, The stripper is connected to the regenerator, so that the catalyst to be regenerated after being stripped by the stripper enters the regenerator for regeneration; the regenerator is also connected to the constant linear velocity fluidized bed reactor, so that the regenerated catalyst after being regenerated by the regenerator is circulated back to the constant linear velocity fluidized bed reactor; the regenerator also includes a flue gas circulation system, and part or all of the regenerated flue gas is circulated back to the regenerator; An oil-gas separation system, the oil-gas separation system being in communication with the oil-gas outlet of the isolinear fluidized bed reactor; Preferably, the isolinear fluidized bed reactor is provided with a light hydrocarbon feedstock oil inlet and a heavy oil inlet, and the heavy oil inlet is provided above the light hydrocarbon feedstock oil inlet; More preferably, the heavy oil inlet is communicated with the oil slurry outlet of the oil-gas separation system.

11. The reaction system according to claim 10, characterized in that: The reaction system further comprises a second reactor, which is a heavy oil catalytic cracking reactor, wherein the outlet of the second reactor is connected to the outlet section of the isolinear fluidized bed reactor, and the second mixed material containing the second oil gas and the second spent catalyst obtained after the second catalytic cracking reaction in the second reactor is separated in a cyclone separator; Preferably, the second reactor is a riser reactor or a variable diameter riser bed reactor; More preferably, the inlet of the second reactor is communicated with the oil slurry outlet of the oil-gas separation system.

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