Process for the catalytic cracking of hydrocarbons for the maximum production of propylene and the reaction system thereof

Abstract

The present application provides a method for maximum production of propylene by catalytic cracking of hydrocarbons and a reaction system thereof, which comprises contacting light petroleum hydrocarbons such as diesel oil with a mesoporous molecular sieve catalyst in an isokinetic fluidized bed reactor, and maintaining self-heating balance by recycling regeneration flue gas to maximum production of propylene and the like. The method of the present application can process not only light hydrocarbons such as diesel oil, but also heavy oils such as naphtha, wax oil and residual oil, has high propylene yield, and can achieve self-heating balance, thereby not only solving the problem of excess production capacity of refinery diesel oil, but also making up for the deficiency of chemical materials.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of catalytic cracking of petroleum hydrocarbons, and in particular to a method and a reaction system for catalytic cracking to produce maximum amount of propylene. BACKGROUND

[0002] In recent years, the consumption ratio of diesel to gasoline in the product oil market has been continuously decreasing, and the diesel consumption has been zero growth or negative growth since it reached a peak of 176 Mt in 2014. According to statistics, a heavy-duty diesel vehicle emits about 150 times as much as a light-duty gasoline vehicle of the same stage per unit mileage, and about 750 times as much as a light-duty gasoline vehicle of the same stage per year. This pollution situation further restricts the development of diesel vehicles. It is predicted that by 2025, the diesel consumption will decrease to 168 Mt, and the consumption ratio of diesel to gasoline will decrease from the current 1.4 to less than 1. This will mean that there will be more than 100 million tons of excess gasoline and diesel products, and the high particulate matter emission of diesel engines will further restrict the use of diesel. Therefore, it is urgent to reduce the diesel to gasoline ratio of refinery products and find a way out for diesel. Straight-run diesel accounts for about 50% of the total diesel, and reducing the production of straight-run diesel or converting it into other high-value-added products to adapt to the changes in future diesel demand is of great significance to ensure the balance between supply and demand in the product oil market in China.

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

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

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

[0006] Patents CN104418685B and CN104418686A both disclose a catalytic cracking method of straight-run diesel oil in a riser reactor with methane as a diluent and heat exchange between spent catalyst and flue gas. Patent CN104418686A also discloses a cracking gasoline aromatic extraction and H2+C1-C4 alkane steam cracking technology. As described in the two patents, the mature fluidized bed technology can realize continuous reaction-regeneration and solve the heat balance problem by setting a spent catalyst and flue gas heat exchanger. At a reaction temperature of 630 DEG C and a catalyst / oil mass ratio of 18, the diesel oil conversion rate is as high as 83.83% by carbon four recycling, and the ethylene and propylene yields are 16.52% and 35.19%, respectively; however, the heat exchange between the spent catalyst and the flue gas requires an additional heat exchanger, the process is complex, the equipment investment is high, the heat exchange efficiency is low, and the flue gas contains a certain amount of oxygen, which is not fully combusted with the spent catalyst, and hidden dangers such as tail combustion are prone to occur.

[0007] Therefore, in order to meet the increasing demand for low-carbon olefins and high-octane clean gasoline and solve the outlet of excess diesel oil, it is necessary to develop a production method for converting diesel oil into chemical materials such as propylene. SUMMARY

[0008] The purpose of the present application is to provide a method for converting a maximum amount of light petroleum hydrocarbons such as diesel oil into chemical materials such as propylene, with a high yield of low-carbon olefins and self-heat balance.

[0009] The first aspect of the present application provides a method for producing propylene by catalytic cracking of hydrocarbons in a maximum amount, which comprises:

[0010] (1) performing first catalytic cracking of a light hydrocarbon raw oil in the presence of a catalyst in an isokinetic fluidized bed reactor to obtain a first oil catalyst material comprising a first spent catalyst and a first oil gas;

[0011] (2) separating the first oil agent material in a cyclone separator, and sending the separated oil gas into an oil gas separation system to separate products, to obtain products including ethylene, propylene, BTX, and methylnaphthalene oil;

[0012] (3) sending the separated spent catalyst into a regenerator to perform oxygen-containing regeneration, and recycling the regenerated catalyst back to the isokinetic fluidized bed reactor, wherein part or all of the flue gas after regeneration is recycled back to the regenerator;

[0013] The catalyst comprises a 10-member ring structure mesoporous molecular sieve with an average pore size of 0.5-0.6 nm, and the mesoporous molecular sieve accounts for 30-50% by weight of the total amount of the catalyst.

[0014] According to the method of the first aspect of the application, in the isokinetic 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 raw 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 application, the reaction section of the isokinetic fluidized bed reactor is a variable diameter with a diameter gradually increasing from bottom to top.

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

[0017] According to the method of the first aspect of the application, the oxygen-containing regeneration atmosphere is an oxygen-rich and / or pure oxygen atmosphere.

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

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

[0020] According to the method of the first aspect of the application, the catalyst comprises a mesoporous molecular sieve, optionally a mesoporous molecular sieve, optionally an inorganic oxide, and optionally a clay, wherein the mesoporous molecular sieve is a 12-member 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 40-150 microns.

[0022] More preferably, the catalyst is modified with an oxide of one or more metals and / or non-metals selected from Group IA, Group IIA, Group VA, Group VIA, Group VIIA, Group IB, Group IIB or transition metals, said oxide being present in an amount of 0.5 to 5.0 wt% of the total catalyst.

[0023] According to the method of the first aspect of the present application, wherein the light hydrocarbon feed oil is diesel oil;

[0024] Preferably, the diesel oil includes straight-run diesel oil, catalytically cracked diesel oil and / or hydroprocessed diesel oil; the diesel oil has a boiling point of 180 to 380°C and a density of not more than 860 kg / m 3 .

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

[0026] The fluidizing medium of the isokinetic fluidized bed reactor is steam, preferably, the mass ratio of the steam to the feed oil is 0.15 to 0.25.

[0027] According to the method of the first aspect of the present application, wherein the method further comprises feeding heavy oil into the isokinetic fluidized bed reactor, the feeding position of the heavy oil being above the feeding position of the light hydrocarbon feed 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 application, wherein 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 catalyst material comprising second oil gas and second spent catalyst.

[0030] The second mixture is separated in a cyclone separator.

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

[0032] The second aspect of the present application provides a reaction system for maximum production of propylene by catalytic cracking of hydrocarbons, the reaction system comprising:

[0033] The isokinetic fluidized bed reaction system comprises:

[0034] - an isokinetic fluidized bed reactor,

[0035] - a cyclone separator, and

[0036] - a stripper.

[0037] wherein the cyclone separator is arranged at the top of the isokinetic fluidized bed reactor and is in communication with the stripper, so that the spent catalyst separated by the cyclone separator is stripped in the stripper;

[0038] a regenerator,

[0039] wherein the stripper is in communication with the regenerator, so that the spent catalyst stripped by the stripper is regenerated in the regenerator; the regenerator is also in communication with the isokinetic fluidized bed reactor, so that the regenerated catalyst regenerated by the regenerator is recycled back to the isokinetic fluidized bed reactor; the regenerator further comprises a flue gas circulation system, and part or all of the flue gas after regeneration is recycled back to the regenerator;

[0040] an oil gas separation system, which is in communication with the oil gas outlet of the isokinetic fluidized bed reactor;

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

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

[0043] According to the reaction system of the second aspect of the present application, wherein the reaction system further comprises a second reactor, which is a heavy oil catalytic cracking reactor, the outlet of the second reactor is connected to the outlet section of the isokinetic fluidized bed reactor, and the second mixture containing second oil gas and 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 in communication with the oil slurry outlet of the oil gas separation system.

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

[0047] (1) The present application uses an isokinetic fluidized bed reactor, which can produce continuously without external heating compared with fixed bed and moving bed reactors; and compared with conventional riser reactors, the oil agent is fully contacted, which is more suitable for catalytic cracking of volume-expanded light hydrocarbons.

[0048] (2) Regeneration in oxygen-rich and / or pure oxygen atmosphere, compared with conventional air regeneration, the air heating heat is less, the charring intensity is high, and the regeneration temperature is also high, which can maintain a higher regenerated catalyst temperature.

[0049] (3) The high-temperature flue gas after regeneration is partially or totally returned to the regenerator, which not only makes full use of oxygen in the flue gas, but also solves the problem of heat carried out of the system by the flue gas and reduces the emission of waste gas such as carbon dioxide, thereby achieving significant energy saving and emission reduction.

[0050] (4) The high-precision separation system is used to separate the liquid product into light gasoline fraction with initial boiling point of -60℃, 60-150℃ BTX fraction, 150-240℃ heavy aromatic fraction, 240-340℃ methylnaphthalene oil fraction and >340℃ oil slurry, which can meet the demand of light hydrocarbon catalytic cracking for producing more chemical materials, and is different from the conventional catalytic cracking separation system, which cuts the liquid product into gasoline fraction (initial boiling point-200℃), diesel fraction (200-360℃) and oil slurry fraction (>360℃). BRIEF DESCRIPTION OF DRAWINGS

[0051] Figure 1 The process flow diagram of one embodiment of the present application is used to illustrate the linear velocity fluidized bed catalytic cracking process of light hydrocarbon raw oil.

[0052] Figure 2 The process flow diagram of one embodiment of the present application is used to illustrate the linear velocity fluidized bed catalytic cracking process of light hydrocarbon raw oil coupled with riser catalytic cracking of heavy oil.

[0053] REFERENCE SIGNS:

[0054] I, pre-lifting section of the reactor; II, reaction section of the reactor; III, outlet section of the reactor; IV, settler; V, cyclone separator; VI, catalyst settling section; 1, linear velocity fluidized bed reactor; 2, light hydrocarbon raw oil; 3, atomized steam I; 4, fluidizing medium I; 5, oil gas pipeline; 6, oil 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 oil; 17, atomized steam II; 18, stripping medium; 19, spent catalyst conveying pipeline; 20, regenerator; 21, oxygen-containing regeneration gas; 22, regenerated catalyst conveying pipeline I; 23, flue gas; 24, flue gas circulation system; 25, riser reactor; 26, fluidizing medium II; 27, regenerated catalyst conveying pipeline II. DETAILED DESCRIPTION

[0055] The present application will be further described in detail by the accompanying drawings and examples. Through these descriptions, the features and advantages of the present application will become more apparent.

[0056] The word "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any implementation described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other implementations. While the application is amenable to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and are described in detail below. The intention is not to limit the application to the particular embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the scope of the application as defined by the appended claims.

[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 there is no conflict.

[0058] Before the technical solutions of the present application are described, the terms used herein are defined as follows:

[0059] The term "BTX" refers to: light aromatic hydrocarbon, benzene, toluene, xylene mixture.

[0060] The present application provides a method for maximum production of propylene by catalytic cracking of hydrocarbons, comprising:

[0061] (1) In an isokinetic fluidized bed reactor, a light hydrocarbon raw oil is subjected to first catalytic cracking in the presence of a catalyst to obtain a first oil catalyst material containing first spent catalyst and first oil gas;

[0062] (2) The first oil catalyst material is separated in a cyclone separator, and the separated oil gas enters an oil gas separation system for product separation to obtain products including ethylene, propylene, BTX, and methylnaphthalene oil;

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

[0064] The catalyst comprises a 10-membered ring structure mesoporous molecular sieve with an average pore size of 0.5-0.6 nm, and the mesoporous molecular sieve accounts for 30-50% by weight of the total amount of the catalyst.

[0065] The isokinetic fluidized bed reactor of the present application refers to a fluidized bed reactor in which the oil gas in the catalytic cracking reaction maintains a relatively uniform linear velocity. Since the catalytic cracking reaction is a rapid volume expansion reaction, the reaction section of the isokinetic fluidized bed reactor has a variable diameter that gradually increases from bottom to top. Preferably, in the isokinetic fluidized bed reactor, the linear velocity of the oil gas is 1.0-2.0 m / s, and the catalyst circulation rate is 150-200 kg / (m 2 Compared with a common fluidized bed with a uniform diameter, in the isokinetic fluidized bed reactor, the oil gas contacts the catalyst in a uniform linear velocity and in a plug flow state, and the catalyst has a high density, so the oil gas is more fully contacted.

[0066] The present inventors have found that (1) diesel catalytic cracking is different from heavy oil catalytic cracking, small molecules are difficult to crack, and thus a high reaction severity is required; (2) an isokinetic fluidized bed reactor is suitable for a volume expansion reaction system and reduces the dry gas and coke yield at a high reaction severity of diesel; (3) the coke yield of diesel catalytic cracking is low, and it is difficult to maintain the heat required for the reaction by self-heating balance using conventional heavy oil regeneration technology; and (4) the oil product cutting of a traditional catalytic cracking oil-gas separation system according to a gasoline fraction (initial boiling point-200°C), a diesel fraction (200-360°C), and an oil slurry fraction (>360°C) cannot meet the demand for producing chemical materials by catalytic cracking of light hydrocarbons.

[0067] The present application solves the problem of self-heating balance of light hydrocarbon catalytic cracking and realizes high conversion at a high reaction temperature of light hydrocarbons by using an isokinetic fluidized bed reactor, oxygen-rich and / or pure oxygen regeneration, and partial and / or total return of high-temperature flue gas after regeneration to the regenerator. Furthermore, the present application realizes accurate separation of liquid products by a high-precision separation system to obtain light gasoline fractions with an initial boiling point of-60°C, 60-150°C BTX fractions, 150-240°C heavy aromatic fractions, 240-340°C methylnaphthalene oil fractions, and >340°C oil slurry, and further produces propylene, BTX, and the required heat for the reactor by recycling light gasoline fractions, light aromatic raffinate, heavy aromatic fractions, and oil slurry.

[0068] Based on the above findings, the present application provides a catalytic cracking method for converting diesel into propylene by using a variable-diameter isokinetic fluidized bed reactor. In the variable-diameter isokinetic fluidized bed reactor, diesel is contacted with a high-activity catalyst to perform a high-temperature, large-dosage oil catalytic cracking reaction. The coked and deactivated catalyst is regenerated in an oxygen-rich and / or pure oxygen atmosphere, and the high-temperature flue gas after regeneration is partially and / or totally returned to the regenerator. Thus, self-heating balance of the light hydrocarbon catalytic cracking reaction and regeneration is realized, high conversion at a high reaction temperature is achieved, and efficient continuous production is realized.

[0069] According to the method of the present application, the reaction oil gas is separated by a high-precision separation system, gas products are separated to obtain ethylene, propylene, C4 olefins, and H2+C1-C4 alkanes, and liquid products are separated to obtain light gasoline fractions with an initial boiling point of-60°C, 60-150°C BTX fractions, 150-240°C heavy aromatic fractions, 240-340°C methylnaphthalene oil fractions, and >340°C oil slurry, and BTX fractions are extracted after hydrogenation to obtain BTX and light aromatic raffinate. Preferably, C4 olefins, light gasoline fractions, light aromatic raffinate, heavy aromatic fractions, and >oil slurry obtained by high-precision separation are returned to the reactor for recycling.

[0070] The application uses the isokinetic fluidized bed reactor, which can continuously produce without external heating compared with fixed bed and moving bed reactors, and the oil agent is fully contacted, which is more suitable for catalytic cracking of volume expansion light hydrocarbons compared with conventional riser reactors.

[0071] The high-temperature flue gas after regeneration is partially or entirely returned to the regenerator, which not only fully utilizes oxygen in the flue gas, but also maintains high regeneration temperature and high regenerator temperature. The heat carried out of the reaction and regeneration system by the flue gas is solved, and the emission of waste gas such as carbon dioxide is reduced, and energy saving and emission reduction are greatly achieved.

[0072] The reactor and the regenerator can be arranged in parallel or overlapped, and the fluidized bed and the settler can be built-in or built-out; air and / or water vapor and other media are used to lift the catalyst to circulate between the reactor and the regenerator.

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

[0074] The catalyst in the reactor can flow upwards or downwards; preferably, the catalyst flows upwards.

[0075] In an embodiment, the reaction section of the isokinetic fluidized bed reactor is a variable diameter section with gradually increasing diameter from bottom to top.

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

[0077] The catalyst in the reactor can flow upwards or downwards; preferably, the catalyst flows upwards.

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

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

[0080] The flue gas temperature circulating back to the regenerator is 420-560℃.

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

[0082] Preferably, the average particle size of the catalyst is 40-150 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 amount of the oxide is 0.5-5.0 wt% of the total catalyst.

[0084] In one 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, 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, NU-87 molecular sieve; and the inorganic oxide is a heat-resistant inorganic oxide, preferably an alumina binder, a silica binder, etc.

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

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

[0087] Preferably, the diesel oil includes straight-run diesel oil, catalytic cracking diesel oil and / or hydrogenated diesel oil; the diesel oil has a boiling point of 180-380°C and a density of no more than 860 kg / m 3 .

[0088] In one embodiment, the light hydrocarbon feed 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 isokinetic fluidized bed reactor is steam, and preferably, the mass ratio of the steam to the feed oil is 0.15-0.25.

[0090] The preheating of the feed can be achieved by heating with a heating furnace or by heat exchange with the product to the preheating temperature.

[0091] In an embodiment, the method further comprises feeding heavy oil into the isokinetic fluidized bed reactor, the feeding position of heavy oil being above the feeding position of the light hydrocarbon feedstock oil.

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

[0093] In an 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 mixture comprising second oil gas and second spent catalyst;

[0094] subjecting the second mixture to separation in a cyclone separator;

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

[0096] The present application also provides a reaction system for maximum production of propylene by catalytic cracking of hydrocarbons, comprising:

[0097] an isokinetic fluidized bed reaction system, comprising:

[0098] an isokinetic fluidized bed reactor,

[0099] a cyclone separator, and

[0100] a stripper,

[0101] wherein the cyclone separator is arranged at the top of the isokinetic fluidized bed reactor and is in communication with the stripper, so that the spent catalyst separated by the cyclone separator is stripped in the stripper;

[0102] a regenerator,

[0103] wherein the stripper is in communication with the regenerator, so that the spent catalyst stripped by the stripper enters the regenerator for regeneration; the regenerator is also in communication with the isokinetic fluidized bed reactor, so that the regenerated catalyst regenerated by the regenerator is recycled back to the isokinetic fluidized bed reactor; the regenerator further comprises a flue gas circulation system, and part or all of the flue gas after regeneration is recycled back to the regenerator;

[0104] an oil-gas separation system, which is in communication with the oil-gas outlet of the isokinetic fluidized bed reactor;

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

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

[0107] In one embodiment, the reaction system further comprises a second reactor, which is a heavy oil catalytic cracking reactor, the outlet of the second reactor is connected to the outlet section of the iso-kinetic fluidized bed reactor, and a second mixture comprising second oil gas and second spent catalyst obtained after a 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 in communication with the slurry oil outlet of the oil-gas separation system.

[0110] In one embodiment, the reaction section of the iso-kinetic fluidized bed reactor is a variable-diameter riser with a diameter gradually increasing from bottom to top.

[0111] In one specific embodiment of the present application, as shown in Figure 1 In this embodiment, an upflow variable-diameter iso-kinetic fluidized bed reactor 1 is used, and the light hydrocarbon raw oil 2 is fed into the reactor from the bottom to contact the regenerant for catalytic cracking reaction, the spent catalyst after the reaction is regenerated after being separated from the oil gas, and part of the flue gas after regeneration is recycled back to the regenerator. The process flow is as follows:

[0112] The light hydrocarbon raw material oil 2 is atomized by the atomizing steam I 3 into the variable-diameter reactor reaction section II of the isokinetic fluidized bed reactor 1, and the hot regenerated agent is introduced into the fluidized bed reactor pre-lifting section I through the regenerated agent conveying pipeline 18, and then goes up into the reactor reaction section II under the fluidization of the fluidization medium I 4, and the light hydrocarbon raw material oil 2 contacts the hot regenerated agent to carry out the catalytic cracking reaction; after the reaction, the oil gas and the catalyst enter the cyclone separator V through the reactor outlet section III to carry out the oil and catalyst separation, and then the separated catalyst is settled into the reactor stripping section, is stripped by the stripping medium 18, and then enters the regenerator 20 through the spent agent conveying pipeline 19; the spent agent is regenerated in the oxygen-containing atmosphere in the regenerator 20, the oxygen-containing regeneration gas 21 includes air, oxygen and the like, the regeneration temperature is 620-720 DEG C, and the regenerated catalyst is recycled; part of the flue gas 23 after regeneration is circulated back to the regenerator 20 through the flue gas circulation system 24; the separated reaction oil gas enters the high-precision oil gas separation system 6 through the reaction oil 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, methylnaphthalene oil fraction 14 and oil slurry 15 are separated; and the C4 olefins 10, the light gasoline fraction 11, the heavy aromatic fraction 13 and the oil slurry 15 can be selected to be reprocessed and / or not reprocessed according to the production needs. In order to meet the demand of producing chemical materials, the C4 olefins 10, the light gasoline 11 and the heavy aromatic fraction 13 are preferentially selected to be reprocessed, and the reprocessing can be mixed with the light hydrocarbon raw material oil 2 and then enters the isokinetic fluidized bed reactor 1, and it is further preferred to enter the bottom of the variable-diameter reactor reaction section II, that is, to enter the upper part of the light hydrocarbon raw material oil nozzle. In order to meet the need of self-heat balance of the device, the oil slurry is preferentially selected to be reprocessed, that is, the oil slurry and / or heavy raw material oil 16 is atomized by the atomizing steam II 17 and then enters the reactor, and it is preferably entered into the middle part of the variable-diameter reactor reaction section II, that is, to enter the upper part of the light hydrocarbon raw material oil nozzle.

[0113] Figure 2 The process flow diagram of another embodiment of the present application is shown in the figure, and the light hydrocarbon raw material oil uses the variable-diameter isokinetic fluidized bed reactor 1, which is the same as in example 1, but the oil slurry reprocessing and / or heavy raw material oil 12 enters the conventional lifting pipe reactor 25, and the two reactors can each use a separate settler or share one settler, and both of them use one settler in this example. The process flow is as follows:

[0114] The light hydrocarbon feed oil 2 is atomized by atomizing steam I 3 and introduced into the bottom of the variable-diameter reaction section II of the isokinetic fluidized bed reactor 1, and the hot regenerant is introduced into the pre-lifting section I of the fluidized bed reactor through the regenerant conveying pipeline 18 and ascends into the reaction section II of the reactor under the fluidization of the fluidization medium 4, and the light hydrocarbon feed oil 2 contacts the hot regenerant to perform catalytic cracking reaction; the heavy feed oil 16 is atomized by atomizing steam II 17 and introduced into the lower part of the riser reactor 25, and the hot regenerant is introduced into the bottom of the riser reactor 25 through the regenerant conveying pipeline II 27 and ascends under the fluidization of the fluidization medium II 26, and the heavy feed oil 16 contacts the hot regenerant to perform catalytic cracking reaction; the oil gas after the reaction of the light hydrocarbon feed oil 2 and the heavy feed oil 16 is introduced into the cyclone separator V to perform oil agent separation; the oil gas after the reaction and the catalyst are introduced into the cyclone separator V through the reactor outlet section III to perform oil agent separation, and the separated catalyst is settled into the reactor stripping section, stripped by the stripping medium 18, and then introduced into the regenerator 20 through the spent catalyst conveying pipeline 19; the spent catalyst is regenerated in the oxygen-containing atmosphere in the regenerator 20, the oxygen-containing regeneration gas 21 includes air, oxygen and the like, the regeneration temperature is 620-720℃, and the regenerated catalyst is recycled; part of the flue gas 23 after regeneration is circulated back to the regenerator 20 through the flue gas circulation system 24; the separated reaction oil gas is introduced into the high-precision oil gas separation system 6 through the reaction oil gas pipeline 5, and 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, the light gasoline fraction 11, the heavy aromatic fraction 13 and the oil slurry 15 can be selected to be reprocessed and / or not reprocessed according to production needs. The oil slurry 15 can be reprocessed into the middle part of the variable-diameter reaction section II of the isokinetic fluidized bed reactor 1, and the heavy feed oil 16 is preferentially selected and / or atomized by atomizing steam II 17 and then introduced into the riser reactor 25. In order to meet the demand for producing chemical materials, the C4 olefins 10, the light gasoline 11 and the heavy aromatic fraction 13 are preferentially selected to be reprocessed, and the reprocessing can be performed into the isokinetic fluidized bed reactor 1, and the reprocessing is preferentially performed into the bottom of the riser reactor 25, that is, the catalytic cracking reaction is performed by feeding the heavy feed oil 16 into the lower part of the nozzle.

[0115] The present method will be further illustrated by the following examples. The raw materials used in the examples can be obtained by commercial purchase.

[0116] The following examples will further illustrate the present method, but do not limit the present method.

[0117] The light hydrocarbon feed used in the examples is straight-run diesel oil of a certain refinery, and the heavy feed oil is hydrocracked wax oil after hydrocracking of wax oil of a certain refinery, and the properties of the two are shown in Table 1.

[0118] The catalyst used in the examples is the same, and the preparation method is briefly described as follows:

[0119] 1) 18.8 kg of high water content kaolin (Suzhou porcelain clay company industrial product, solid content 71.6%) was slurried with 125 kg of de-cationic water, then 13.7 kg of pseudo-boehmite (Shandong aluminum plant industrial product, solid content 63%) was added, the pH was adjusted to 2-4 with hydrochloric acid, and stirred until uniform, then aged for 1 hour at 60-70°C while maintaining the pH at 2-4, the temperature was then reduced to below 60°C, and 10.4 kg of aluminum sol (Sinopec Catalyst Qilu Branch product, Al203 content 21.7%) was added, and stirred for 40 minutes to obtain a mixed slurry.

[0120] 2) 18.5 kg of ZRP-2 molecular sieve with MFI structure (Sinopec Catalyst Qilu Branch industrial product, Si02 / Al203 = 39, phosphorus content P205 = 2.1 wt%, iron content Fe203 = 3.1 wt% on a dry basis) and 6.3 kg of beta molecular sieve (Sinopec Catalyst Qilu Branch industrial product, Si02 / Al203 = 52) were added to the mixed slurry obtained in step 1), stirred until uniform, placed in a binder, and an appropriate amount of water was added, stirred until uniform, and left to stand in air for 4 hours, then spray dried to form a shape.

[0121] 3) The catalyst formed by spray drying in step 2) was dried in a drying oven at 120°C for 3 hours, then washed with ammonium dihydrogen phosphate solution (phosphorus content 1%), to remove free Na + and then dried again at 120°C for 3 hours to obtain the catalyst, which is referred to as CAT-3.

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

[0123] Example 1

[0124] This example was carried out according to the method of Example 1, except that the amount of pseudo-boehmite was increased to 22.6 wt%. Figure 1The process was tested using straight-run diesel A in Table 1 as the raw material, and a CAT-3 catalyst was used in the test in the isokinetic fluidized bed reactor. The raw material oil A was preheated to 340°C and then entered the reaction section of the isokinetic fluidized bed reactor, and the catalytic cracking reaction was carried out under the conditions of a reaction pressure of 0.40 MPa, water vapor as the fluidizing medium, a mass ratio of atomized steam to raw material oil of 0.20, and a reaction temperature of 640°C (measured at the outlet of the reactor), a weight ratio of catalyst to raw material oil of 7.5, and a reaction time of 5.0 seconds. After the reaction, oil agent separation was carried out, and the separated reaction oil gas was separated by a high-precision oil gas separation system to obtain products H2, ethylene, propylene, C1-C4 alkanes, BTX, methyl naphthalene oil, and C4 olefins, light gasoline fraction, heavy aromatic fraction, and oil slurry, and the C4 olefins, light gasoline fraction, heavy aromatic fraction, and oil slurry were recycled. The spent catalyst after oil agent separation was sent to the regenerator after steam stripping to remove the oil gas adsorbed inside, and the spent catalyst was regenerated by contacting with oxygen as the regeneration gas at a regeneration temperature of 660-690°C. The regenerated regenerated catalyst was recycled, and 50% of the flue gas after regeneration was recycled at a temperature of 500°C to maintain the dense phase temperature of the regenerator at 690°C. The operating conditions and product distribution are shown in Table 3.

[0125] As can be seen from Table 3, in Example 1, the straight-run diesel was catalytically cracked in the isokinetic fluidized bed reactor, the propylene yield was 27.63 wt%, the ethylene yield was 10.74 wt%, the light aromatic hydrocarbon (benzene + toluene + xylene) yield was 12.60 wt%, and the coke yield was 6.35 wt%

[0126] Comparative Example 1

[0127] The catalytic cracking reaction was carried out by using the same raw material oil and catalyst as in Example 1 and under the same process conditions, except that: 1) a riser reactor was used in Comparative Example 1; 2) air was used as the regeneration gas, and the flue gas was not recycled; and 3) in order to maintain the same process conditions as in Example 1, combustion oil was sprayed in the regenerator to provide heat. The operating conditions and product distribution are shown in Table 3.

[0128] As can be seen from Table 3, compared with Example 1 (isokinetic fluidized bed reactor) and Comparative Example 1 (riser reactor), the propylene yield was increased by 9.11 percentage points, the ethylene yield was increased by 3.23 percentage points, the light aromatic hydrocarbon (benzene + toluene + xylene) yield was increased by 1.18 percentage points, and the coke yield was decreased by 1.63 percentage points.

[0129] Example 2

[0130] This example was carried out according to the process of Example 1, except that the raw material oil was changed to straight-run diesel B in Table 1. Figure 2The process was tested using 70% straight-run diesel A and 30% hydrocracked tail oil B in Table 1 as raw materials, which were respectively tested in the isokinetic fluidized bed reactor and the riser reactor using CAT-3 catalyst. The raw oil A was preheated to 300°C and then entered the reaction section of the isokinetic fluidized bed reactor, and the raw oil B was preheated to 300°C and then entered the bottom of the conventional riser reactor. Both were tested under the conditions of a reaction pressure of 0.30 MPa, water vapor as the fluidizing medium, a mass ratio of atomized steam to raw oil of 0.15, and a reaction temperature (measured at the outlet of the reactor) of 600°C, a weight ratio of catalyst to raw oil of 9.0, and a reaction time of 8.0 seconds. The catalytic cracking reaction was carried out as the fluidizing medium flowed upward in the different reactors. The oil gas and catalyst after reaction of the raw oil B in the riser reactor were combined into the isokinetic fluidized bed reactor, and the oil gas after reaction of the raw oil A was separated from the catalyst. The separated reaction oil gas was separated by a high-precision oil gas separation system to obtain products H2, ethylene, propylene, C1-C4 alkanes, BTX, methyl naphthalene oil, C4 olefins, light gasoline fraction, heavy aromatic fraction, and oil slurry. The C4 olefins, light gasoline fraction, heavy aromatic fraction, and oil slurry were recycled. The spent catalyst after oil agent separation was sent to the regenerator after stripping with water vapor to remove the oil gas adsorbed inside. The rich oxygen air with 20% oxygen and 80% air was used as the regeneration gas, and the spent catalyst was regenerated at a regeneration temperature of 650-670°C. The regenerated regenerated catalyst was recycled, and part of the flue gas after regeneration was recycled. The circulating flue gas temperature was 450°C, and the dense phase temperature in the regenerator was maintained at 670°C. The operating conditions and product distribution are listed in Table 3.

[0131] As can be seen from Table 3, in Example 2, the hydrocracked diesel was catalytically cracked in the isokinetic fluidized bed reactor, and the cracking tail oil was catalytically cracked in the riser reactor. The propylene yield was 25.41 wt%, the ethylene yield was 20.57 wt%, the light aromatic hydrocarbon (benzene + toluene + xylene) yield was 15.39 wt%, and the coke yield was 7.84 wt%

[0132] Comparative Example 2

[0133] The same raw oil and catalyst as in Example 1 were used for catalytic cracking under the same process conditions, except that: 1) both the hydrocracked diesel A and the cracking tail oil B in Comparative Example 2 were tested in the riser reactor; 2) air was used as the regeneration gas, and the flue gas was not recycled; 3) to maintain the same process conditions as in Example 2, combustion oil was needed to be sprayed 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, the propylene yield of Example 2 (isokinetic fluidized bed reactor) is increased by 4.84 percentage points, the ethylene yield is increased by 2.25 percentage points, the light aromatic hydrocarbon (benzene + toluene + xylene) yield is increased by 1.37 percentage points, and the coke yield is decreased by 1.24 percentage points, as compared with Comparative Example 2 (riser reactor).

[0135] The application has been described above with reference to preferred embodiments. However, these embodiments are merely exemplary and are presented for purposes of illustration only. Variations and modifications to the present application can be made based on what is described herein, and the application is to be limited only by the claims.

[0136] Table 1

[0137] Feedstock oil name Straight-run diesel Heavy feedstock oil Feedstock oil number A B 20°C density, kg / m3 3 ]] 840.4 898.2 Sulfur content, wt% 0.938 0.17 Nitrogen content, wt% 0.0085 0.07 Four components Saturated hydrocarbons, wt% 75.7 56.5 Aromatics, wt% 24.3 43.5 ASTM D86 distillation range, °C Initial boiling point 194 358 10％ 217 389 50％ 283 430 90％ 340 515 Final boiling point 364 562

[0138] Table 2

[0139]

[0140]

[0141] Table 3

[0142]

Claims

1. A process for the catalytic cracking of hydrocarbons to maximize the production of propylene, characterized in that, The method comprises: (1) in an isokinetic fluidized bed reactor, subjecting a light hydrocarbon raw oil to a first catalytic cracking in the presence of a catalyst to obtain a first oil catalyst material comprising a first spent catalyst and a first oil gas; (2) subjecting the first oil catalyst material to separation in a cyclone separator, the separated oil gas being subjected to product separation in an oil gas separation system to obtain products including ethylene, propylene, BTX and methylnaphthalene oil; (3) the separated spent catalyst being subjected to oxygen-containing regeneration in a regenerator, the regenerated catalyst being recycled back to the isokinetic fluidized bed reactor, wherein part or all of the flue gas after regeneration is recycled back to the regenerator, and the oxygen-containing regeneration atmosphere is an oxygen-rich and / or pure oxygen atmosphere; The catalyst comprises a 10-member ring structure mesoporous molecular sieve with an average pore size of 0.5-0.6 nm, and the mesoporous molecular sieve accounts for 30-50% of the total weight of the catalyst.

2. The method of claim 1, wherein, In the isokinetic 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 raw oil is 6-12:1, and the reaction time is 4.0-9.0 seconds.

3. The method of claim 1, wherein, The reaction section of the isokinetic fluidized bed reactor is a variable diameter with a diameter gradually increasing from bottom to top.

4. The method of claim 3, wherein, In the isokinetic fluidized bed reactor, the oil gas linear velocity is 1.0-2.0 m / s, and the catalyst circulation rate is 150-200 kg / (m 2 ·s).

5. The method of claim 1, wherein The temperature of the regenerator is 620-760°C, and the pressure is 0.3-0.6 MPa; and / or The temperature of the flue gas recycled back to the regenerator is 420-560°C.

6. The method of claim 1, wherein, The catalyst comprises a mesoporous molecular sieve, optionally a mesoporous molecular sieve, optionally an inorganic oxide, and optionally a clay, wherein the mesoporous molecular sieve is a 12-member ring structure molecular sieve with an average pore size of 0.55-0.75 nm.

7. The method of claim 5, wherein, The average particle size of the catalyst is 40-150 microns.

8. The method of claim 7, wherein, The catalyst is modified with an oxide of one or more metals and / or non-metals selected from Group IA, Group IIA, Group VA, Group VIA, Group VIIA, Group IB, Group IIB or transition metals, and the oxide accounts for 0.5-5.0% of the total weight of the catalyst.

9. The method of claim 1, wherein, The light hydrocarbon raw oil is diesel oil.

10. The method of claim 9, wherein, The diesel oil includes straight-run diesel oil, catalytically cracked diesel oil and / or hydrogenated diesel oil; the diesel oil has a boiling point of 180-380℃ and a density of not more than 860 kg / m 3 .

11. The method of claim 1, wherein, The light hydrocarbon raw oil is preheated before entering the reactor, and the preheating temperature is 200-400°C; and / or The fluidizing medium of the isokinetic fluidized bed reactor is steam.

12. The method of claim 11, wherein, The preheating temperature is 240-340°C; and / or The mass ratio of steam to raw oil is 0.15-0.

25.

13. The method of claim 1, wherein, The method further comprises feeding heavy oil into the isokinetic fluidized bed reactor, and the feeding position of the heavy oil is above the feeding position of the light hydrocarbon raw oil. The heavy oil is wax oil, residual oil and / or oil slurry separated by the oil gas separation system in step (2).

14. The method of claim 1, wherein, 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 catalyst material comprising a second oil gas and a second spent catalyst; The second mixture is subjected to separation in a cyclone separator.

15. The method of claim 14, wherein, The second reactor is a riser reactor or a variable-diameter riser bed reactor.

16. A reaction system for carrying out the process of claim 1 for the maximum production of propylene by catalytic cracking of hydrocarbons, characterized by, The reaction system comprises: The isokinetic fluidized bed reaction system comprises: an isokinetic fluidized bed reactor, a cyclone separator, and a stripper, wherein the cyclone separator is arranged at the top of the isokinetic fluidized bed reactor and is in communication with the stripper, so that the spent catalyst separated by the cyclone separator is stripped in the stripper; a regenerator, wherein the stripper is in communication with the regenerator, so that the spent catalyst stripped by the stripper is regenerated in the regenerator; the regenerator is also in communication with the isokinetic fluidized bed reactor, so that the regenerated catalyst regenerated by the regenerator is recycled back to the isokinetic fluidized bed reactor; the regenerator further comprises a flue gas circulation system, and part or all of the flue gas after regeneration is recycled back to the regenerator; an oil-gas separation system, which is in communication with the oil-gas outlet of the isokinetic fluidized bed reactor.

17. The reaction system of claim 16, wherein, The isokinetic fluidized bed reactor is provided with a light hydrocarbon raw oil inlet and a heavy oil inlet, and the heavy oil inlet is arranged above the light hydrocarbon raw oil inlet.

18. The reaction system of claim 17, wherein, The heavy oil inlet is in communication with the oil slurry outlet of the oil-gas separation system.

19. The reaction system of claim 16, wherein, The reaction system further comprises a second reactor, which is a heavy oil catalytic cracking reactor, and the outlet of the second reactor is connected to the outlet section of the isokinetic fluidized bed reactor, and the second mixture containing second oil gas and second spent catalyst obtained after the second catalytic cracking reaction in the second reactor is separated in the cyclone separator.

20. The reaction system of claim 19, wherein, The second reactor is a riser reactor or a variable-diameter riser bed reactor.

21. The reaction system of claim 20, wherein, The inlet of the second reactor is in communication with the oil slurry outlet of the oil-gas separation system. The reaction system further comprises a second reactor, which is a heavy oil catalytic cracking reactor, and the outlet of the second reactor is connected to the outlet section of the isokinetic fluidized bed reactor, and the second mixture containing second oil gas and second spent catalyst obtained after the second catalytic cracking reaction in the second reactor is separated in the cyclone separator. The second reactor is a riser reactor or a variable-diameter riser bed reactor. The inlet of the second reactor is in communication with the oil slurry outlet of the oil-gas separation system.

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