Methods and systems for direct catalytic cracking of crude oil that can achieve thermal equilibrium

Abstract

This application relates to a method and system for direct catalytic cracking of crude oil that can achieve thermal equilibrium. The method includes: crude oil undergoing catalytic cracking in a first fluidized bed reactor; recalcitrant components undergoing catalytic cracking in a second fluidized bed reactor; the reaction products and spent catalyst undergoing gas-solid separation; the spent catalyst is then sequentially stripped, replenished with raw coke, regenerated by coke burning, and partially reduced before being returned to the reactor for recycling; the reaction products are separated to obtain ethylene, propylene, recalcitrant components, and other products, wherein the recalcitrant components enter the second fluidized bed reactor for further catalytic cracking to obtain ethylene and propylene. When the catalytic cracking method and system of this application are used for crude oil catalytic cracking, the thermal equilibrium problem of the reaction itself can be solved, and low-carbon olefins and light aromatics and other chemical feedstocks can be produced with high selectivity, achieving efficient utilization of crude oil resources.

Description

Technical Field

[0001] This application relates to the petrochemical field, and more specifically, to a method and system for direct catalytic cracking of crude oil. Background Technology

[0002] With overcapacity in oil refining and a slowing demand for refined oil products, ethylene, propylene, and BTX (benzene-toluene-xylene) are key basic organic synthesis raw materials in huge demand, while demand for chemical products remains strong. Existing technologies for producing propylene and BTX from petroleum are developed based on traditional oil refining processes, which suffer from long production processes, low chemical yields, and insignificant economic benefits. The key to solving these problems is to develop core technologies that enable the targeted conversion of crude oil hydrocarbon molecules into chemicals. Therefore, in recent years, international petrochemical companies, represented by ExxonMobil and Saudi Aramco, have begun to innovate traditional refining processes. These companies have revolutionized traditional oil refining processes, elevating integrated refining and chemical production to a new level of direct crude oil-to-chemicals conversion.

[0003] ExxonMobil is a pioneer in the research and development of crude oil steam cracking to olefins, and was the first company to build an industrial-scale demonstration plant. It has also applied for a series of patents, such as CN101583697. The company's direct olefins process involves crude oil directly entering a steam cracker, where it undergoes flash evaporation to separate light and heavy components. The light components (gaseous components) are then further cracked in the steam cracker, while the heavy components (liquid components) are used as refinery feedstock. If the selected crude oil is sufficiently light and has no fractions above 593°C (i.e., no bottom residue), it can be produced without relying on a refinery. The company's first industrial-scale plant used ultralight paraffinic Tapis crude oil with an API gravity of 42.7 as feedstock.

[0004] Saudi Aramco's technological strength lies in its use of crude oil pretreatment and hydrotreating technologies to minimize the impact of non-volatile components in crude oil on steam cracking. Simultaneously, a vapor-liquid (steam and liquid) separation device is installed between the convection and radiant sections of the steam cracker to remove non-volatile liquids (liquid phases), ensuring that the material entering the radiant section is free of liquid entrainment, thus preventing coking in the furnace tubes. The heavier components are then fed into the catalytic cracking unit. This can be described as an integrated process for producing olefins and aromatics from crude oil, combining hydrotreating, steam cracking, and catalytic cracking.

[0005] Sinopec's crude oil-to-chemicals technology is mainly divided into two technical routes. The first is crude oil steam cracking technology, which uses light crude oil as raw material and has a chemical yield of about 50%. The second is catalytic cracking technology, in which crude oil is desalted and dehydrated to separate light and heavy components. The light components (light feed) and the heavy components (heavy feed) are reacted with high-temperature catalysts in two separate catalytic cracking reactors under a steam atmosphere to produce high-value-added products. Alternatively, the light components and heavy components can react in different reaction zones of the same reactor, with a total yield of low-carbon olefins and light aromatics of over 50%.

[0006] Due to the presence of heavy components in crude oil that are difficult to vaporize, existing crude oil-to-chemicals technologies are only suitable for low-sulfur paraffin-based crude oils with an API gravity of around 45. Other crude oil-to-chemicals technologies vary among companies depending on the processing methods for heavy components in the crude oil, but all employ fractionation, combining processes based on the properties of distillate oils at different boiling points to produce chemicals. Compared to traditional refining processes, this only changes the boiling point and quantity of the fractionated oils and integrates existing processing techniques, failing to achieve a fundamental technological revolution. Furthermore, these existing combined technologies are more suitable for light crude oils or paraffin-based crude oils; when using heavy crude oils or intermediate-based crude oils as feedstocks, the yield of high-value-added chemical feedstocks such as low-carbon olefins and aromatics is low. Summary of the Invention

[0007] The purpose of this application is to provide a method for direct catalytic cracking of crude oil and a method for systematically producing high value-added products. This method not only has good adaptability to crude oil and high yields of chemical feedstocks such as low-carbon olefins and aromatics, but also achieves self-regulation of thermal balance to meet its own reaction heat requirements.

[0008] A first aspect of the present invention provides a method for direct catalytic cracking of crude oil that can achieve thermal equilibrium, comprising:

[0009] (1) The first raw material and the regenerated catalyst from the regenerator enter the first fluidized bed reactor for catalytic cracking reaction. Optionally, the reaction products are contacted with the introduced supplementary catalyst and the reaction continues.

[0010] (2) The second raw material is introduced from the downstream feed section of the second fluidized reactor and comes into contact with the reduced catalyst mixture from the catalyst reducer to undergo a cracking reaction. The catalyst mixture includes regenerated catalyst and fresh catalyst.

[0011] (3) The reaction products and the catalyst to be generated in the first fluidized bed reactor and the second fluidized bed reactor enter the oil-solid separation equipment for gas-solid separation, and the reaction oil and gas and the catalyst to be generated are separated. The separated reaction oil and gas are further separated to obtain ethylene, propylene, difficult-to-convert components and other products.

[0012] (4) The separated raw catalyst is stripped and then enters the coking unit. After being mixed with the regenerated catalyst from the regenerator and heated, it comes into contact with the raw coking raw material to produce a coking reaction, thus obtaining the raw catalyst with coke.

[0013] (5) The catalyst with coke enters the regenerator and reacts with oxygen-containing gas to produce a carbonization reaction. The first part of the regenerated catalyst is returned to the coke generator for reaction recycling. The second part of the regenerated catalyst is returned to the first fluidized bed reactor for reaction recycling. The third part of the regenerated catalyst enters the reducer and is mixed with the fresh catalyst. Under the action of the reducing medium, a reduction reaction occurs and energy is released. The catalyst mixture after reduction enters the second fluidized bed reactor for reaction recycling.

[0014] The first raw material is selected from one or more of crude oil, mineral oil, and synthetic oil;

[0015] The second feedstock is self-produced by the equipment and / or other difficult-to-convert components, wherein the difficult-to-convert components are light hydrocarbons and / or light distillate oils.

[0016] According to the method described in the first aspect, the crude oil is a full-fraction crude oil;

[0017] The mineral oil is selected from one or more of coal liquefaction oil, oil sands oil, and shale oil; and / or

[0018] The synthetic oil is a distillate obtained by FT synthesis of coal, natural gas, or bitumen.

[0019] According to the method of the first aspect, the light hydrocarbons include gaseous hydrocarbon products rich in C4 fractions produced by the device itself and / or gaseous hydrocarbons rich in C4 fractions produced by other devices, wherein the C4 olefin content in the gaseous hydrocarbons rich in C4 fractions is greater than 50% by weight.

[0020] Preferably, the difficult-to-convert component is a C4 fraction produced by the device itself.

[0021] According to the method of the first aspect, the light distillate oil comprises light distillate oil produced by the unit with a final boiling point of less than 280-350°C and optionally one or more of the following fractions:

[0022] Other primary processing units produce straight-run naphtha, straight-run kerosene, and straight-run diesel oil;

[0023] Other secondary processed oils include topping oil, residue oil, hydrocracked light naphtha, pentane oil, coking gasoline, Fischer-Tropsch synthetic oil, catalytic cracked light gasoline, hydrotreated gasoline, and hydrotreated diesel.

[0024] According to the method of the first aspect, the first fluidization reactor is selected from one or more of the following in series: a turbulent bed reactor, a fast bed reactor, and a dilute phase transport bed reactor; and / or

[0025] The second fluidized bed reactor is a dilute phase transport bed reactor.

[0026] According to the method described in the first aspect, the catalytic cracking reaction conditions in the first fluidized bed reactor are as follows:

[0027] The reaction temperature is 510-650℃;

[0028] The reaction time is 1-20 seconds;

[0029] The weight ratio of catalyst to feedstock is (3-50):1; and / or

[0030] The reaction pressure is 130-450 kPa;

[0031] Preferably, the first raw material is preheated and steam atomized before entering the first fluidized bed reactor. The preheating temperature is 180-350℃ and the water-to-oil weight ratio is (0.03-0.8):1.

[0032] According to the method described in the first aspect, the second fluidized bed reactor is provided with a main reaction section and one or more feed sections for difficult-to-convert components;

[0033] Preferably, the one or more feed sections for the recalcitrant components are each independently located in the middle to upstream of the second fluidized bed reactor; and / or

[0034] Preferably, the catalyst density in each of the feed sections for the recalcitrant components is 120-290 kg / m³. 3 .

[0035] According to the method described in the first aspect, the catalytic cracking reaction conditions in the second fluidized bed reactor are as follows:

[0036] The reaction temperature is 580-750℃;

[0037] The reaction time is 0.05-5 seconds; and / or

[0038] The weight ratio of catalyst to feedstock oil is (1-50):1;

[0039] Preferably, the second raw material is introduced into the second fluidized bed reactor after being atomized by steam, and the water-to-oil weight ratio is (0.03-0.5):1.

[0040] According to the method described in the first aspect, the weight ratio of fresh catalyst to regenerated catalyst in the catalyst reducer is (0.005-0.3):1.

[0041] According to the method described in the first aspect, the reduction temperature in the catalyst reducer is 550-700℃;

[0042] The restoration time is 2-20 minutes; and / or

[0043] The reducing medium is refinery dry gas and / or small molecule alkanes, wherein the small molecule alkanes are C1-C3 alkanes, preferably refinery dry gas.

[0044] According to the method described in the first aspect, the outlet temperature of the coking device is 550-650°C, and / or the linear velocity is 1.2-2.2 m / s.

[0045] According to the method of the first aspect, the catalyst comprises 0.01-5 wt%, preferably 0.005-2 wt%, of a metal oxide, wherein the metal oxide is selected from one or more of the following: tin, cobalt, iron, molybdenum, manganese, copper, barium, and chromium.

[0046] Preferably, based on the dry weight of the catalyst, the catalyst comprises:

[0047] 0-70 parts by weight, preferably 5-60 parts by weight, more preferably 10-50 parts by weight of clay,

[0048] 5-99 parts by weight, preferably 10-80 parts by weight, more preferably 20-70 parts by weight of adhesive,

[0049] 1-60 parts by weight, preferably 5-45 parts by weight, more preferably 10-40 parts by weight of zeolite, and

[0050] 0.001-5 parts by weight, preferably 0.005-2 parts by weight, of a metal oxide.

[0051] And the total weight of the catalyst is 100 parts by weight;

[0052] The adhesive is an inorganic oxide adhesive, preferably silicon dioxide and / or aluminum oxide;

[0053] The zeolite includes mesoporous zeolite and optional macroporous zeolite. The mesoporous zeolite is ZSM series zeolite and / or ZRP zeolite. The macroporous zeolite is selected from one or more of rare earth Y-type zeolite, rare earth hydrogen Y-type zeolite, ultrastable Y-type zeolite and high silica Y-type zeolite. Preferably, the mesoporous zeolite accounts for 5-100% of the total weight of the zeolite, more preferably 50-90% by weight, and more preferably 20-50% by weight.

[0054] The clay is preferably kaolin and / or hydrous kaolin.

[0055] A second aspect of the present invention provides a system for the direct catalytic cracking of crude oil to produce low-carbon olefins, comprising:

[0056] The catalytic cracking reaction unit includes:

[0057] The first fluidized bed reactor is provided with a pre-lifting medium inlet, a regenerated catalyst inlet, a supplementary catalyst inlet, a feedstock oil inlet, and a first oil-agent mixture outlet;

[0058] The second fluidized bed reactor is provided with a pre-lifting section, a feed section, a main reaction section and an outlet section from bottom to top. The bottom of the pre-lifting section is provided with a reduction catalyst inlet and a pre-lifting medium inlet. The feed section is provided with a difficult-to-convert raw material inlet, a circulating catalyst inlet and an optional outgoing catalyst outlet.

[0059] An oil-liquid separation device is connected to both the outlet of the first oil-liquid mixture from the first fluidized bed reactor and the outlet of the second oil-liquid mixture from the second fluidized bed reactor, such that the first oil-liquid mixture from the first fluidized bed reactor and the second oil-liquid mixture from the second fluidized bed reactor are separated into reaction oil gas and catalyst to be generated by the oil-liquid separation device; and

[0060] A settling device is used to settle and collect the catalyst to be generated after being separated by the oil-based separation equipment. A stripping section is provided below the settling device for stripping the catalyst to be generated. The stripping section is provided with a catalyst outlet and a stripping medium inlet.

[0061] Catalyst regeneration unit, including

[0062] A coking unit is used to bring the catalyst to be generated separated from the catalytic cracking reaction unit into contact with the coking raw material to produce a coking reaction and obtain a catalyst with coke. It is provided with a catalyst inlet, a fluidized medium inlet, a coking raw material inlet, a first gas distributor and a coking catalyst outlet. The catalyst inlet is in fluid communication with the catalyst outlet of the stripping section of the settling tank.

[0063] The regenerator is provided with a coke catalyst inlet, an oxygen-containing gas inlet, a second gas distributor, a cyclone separator, a regenerated flue gas pipeline, and at least one regenerated catalyst outlet; the coke catalyst inlet of the regenerator is in fluid communication with the coke catalyst outlet of the coke reactor; one regenerated catalyst outlet is connected to the regenerated catalyst inlet of the first fluidized bed reactor for recycling a portion of the regenerated catalyst back to the first fluidized bed reactor.

[0064] A regenerated catalyst circulation pipeline is provided between the coking unit and the regenerator, which is used to allow a portion of the regenerated catalyst to enter the coking unit and mix with the catalyst to be generated to jointly react with the coking raw material in the coking reaction.

[0065] A catalyst reducer is provided with a regenerated catalyst inlet, a fresh catalyst inlet, a reduced catalyst outlet, and a reduced medium inlet; the regenerated catalyst inlet of the catalyst reducer is connected to a regenerated catalyst outlet, so that a portion of the regenerated catalyst from the regenerator is reduced in the catalyst reducer; the reduced catalyst outlet of the catalyst reducer is in fluid communication with the reduced catalyst inlet of a second fluidized bed reactor, so that the reduced catalyst is circulated back to the second fluidized bed reactor.

[0066] The catalyst reducer is arranged in parallel or coaxially with the second fluidized bed reactor, and the coke generator is arranged coaxially with the regenerator.

[0067] According to the system described in the second aspect, the connection port of the regeneration catalyst circulation pipeline on the coking unit is located at a distance of 5% to 10% of the height of the coking unit from the bottom of the coking unit; and / or

[0068] The distance between the raw coke inlet and the bottom of the coker is 0% to 50% of the height of the coker.

[0069] According to the system described in the second aspect, the second fluidized bed reactor includes two feed sections connected in sequence, the first feed section is connected to the pre-lifting section, the second feed section is connected to the main reaction section, and an external catalyst circulation pipeline connecting the two feed sections is provided between the first feed section and the second feed section.

[0070] Preferably, the distance from the connection port of the external catalyst circulation pipe on the first feed section to the bottom of the first feed section is 0 to 10% of the height of the second feed section; and / or the distance from the outlet of the catalyst on the second feed section to the bottom of the second feed section is 5% to 20% of the height of the second feed section.

[0071] Compared with the prior art, the method and system of the present invention have the following advantages:

[0072] 1) It can realize the direct catalytic cracking of inferior crude oil, reduce the crude oil distillation process, and has a simple process and low operating cost.

[0073] 2) In the process of crude oil catalytic cracking, the single-pass conversion rate is not pursued. The light distillate oil that is difficult to convert is recycled. By setting up a specific reaction zone, a higher total conversion rate and a higher selectivity of target products can be achieved.

[0074] 3) Based on the reactivity of the difficult-to-convert components, they are introduced into the reactor in a specific feed section of the second fluidized bed reactor. The higher catalyst density and higher catalyst activity in the feed section are beneficial to improving the reaction conversion rate and catalytic selectivity of the difficult-to-convert components.

[0075] 4) The catalyst in the second feed section can be selectively returned to the first feed section to increase the catalyst-to-oil ratio in the first feed section, or it can be selectively removed from the reactor according to the degree of carbonization of the catalyst, which helps to improve the catalyst activity in the reactor.

[0076] 5) A regenerated catalyst reducer is set up. The catalyst contains metals with variable valence states. Energy is stored and released through the gain or loss of electrons between the metal and the metal oxide or the shift of shared electron pairs. This provides heat for the catalytic cracking reaction of the difficult-to-convert components, which can solve the problem of high reaction heat demand of the difficult-to-convert components.

[0077] 6) Setting up a coking unit can solve the problem of insufficient reaction heat when processing high-quality crude oil and achieve thermal balance.

[0078] Using the method described in this application, crude oil can be directly and efficiently used to produce chemical raw materials such as ethylene and propylene, alleviating the oversupply of refined oil products, promoting the deep integration of the refining and petrochemical industries, and facilitating the high-quality development of the refining and chemical industry. Attached Figure Description

[0079] The accompanying drawings are provided to further illustrate the present application and form part of the specification. They are used together with the following detailed description to explain the present application, but do not constitute a limitation thereof. In the drawings:

[0080] Figure 1 A schematic diagram of a process for direct catalytic cracking of crude oil according to one embodiment of this application.

[0081] Explanation of reference numerals in the attached figures:

[0082] 100. First fluidized bed reactor; 101. First pre-lifting medium pipeline; 102. First feed pipeline; 103. First catalyst inlet; 104. First fluidized bed reactor outlet; 200. Settler; 201. Lower stripping section of settler; 202. Stripping medium pipeline; 203. Inclined tube for waiting for regeneration; 204. Oil-catalyst separation device; 205. Gas collection chamber; 206. Large oil-gas pipeline; 300. Second fluidized bed reactor; 301. Second pre-lifting medium pipeline; 303. Second feed pipeline; 304. Third feed pipeline; 305. Fourth feed pipeline; 306. First catalyst circulation pipeline; 307. Catalyst outlet pipeline; 308. Second fluidized bed reactor outlet; 309. Second fluidized bed reactor... 310. Pre-lifting section of the reactor; 311. Main reaction section of the second fluidized bed reactor; 312. First feed section of the second fluidized bed reactor; 400. Regenerator; 401. Oxygen-containing gas inlet; 402. Main air distributor; 403. First regeneration inclined tube; 404. Cyclone separator; 405. Regeneration flue gas recovery pipeline; 406. Second regeneration inclined tube; 500. Catalyst reducer; 501. Reduction medium pipeline; 503. Reduction catalyst pipeline; 504. Fresh catalyst pipeline; 700. Coking unit; 701. Fluidized medium inlet; 702. Gas distributor; 703. Second catalyst circulation pipeline; 704. Coking feed inlet; 705. Catalyst distributor. Detailed Implementation

[0083] The present application will now be described in further detail with reference to the accompanying drawings and embodiments. Through these descriptions, the features and advantages of the present application will become clearer and more apparent.

[0084] The term “exemplary” as used herein means “serving as an example, embodiment, or illustration.” Any embodiment illustrated herein as “exemplary” is not necessarily to be construed as superior to or better than other embodiments. Although various aspects of embodiments are shown in the accompanying drawings, the drawings are not necessarily drawn to scale unless specifically indicated otherwise.

[0085] Any specific numerical value (including the endpoints of a numerical range) disclosed in this application is not limited to the exact value, but should be understood to also include values ​​close to the exact value, such as all possible values ​​within ±5% of the exact value. Furthermore, with respect to the disclosed numerical range, one or more new numerical ranges can be obtained by arbitrarily combining the endpoint values ​​of the range, the endpoint values ​​with specific point values ​​within the range, and the specific point values ​​themselves; these new numerical ranges should also be considered as specifically disclosed herein.

[0086] In this application, the terms "upstream" and "downstream" refer to the direction of reaction material flow. For example, when the reaction material flows from bottom to top, "upstream" refers to the position located at the bottom, while "downstream" refers to the position located at the top.

[0087] In this article, low carbon olefins are a collective term for ethylene, propylene, and butene, and light aromatic hydrocarbons (BTX) are a collective term for benzene (BTX), toluene (T), and xylene (X).

[0088] Unless otherwise stated, the terms used herein have the same meaning as commonly understood by those skilled in the art, and if a term is defined herein and its definition differs from the common understanding in the art, the definition herein shall prevail.

[0089] Furthermore, the technical features involved in the different embodiments of this application described below can be combined with each other as long as they do not conflict with each other.

[0090] This invention provides a direct catalytic cracking method for crude oil that can achieve thermal equilibrium, comprising:

[0091] (1) The first raw material and the regenerated catalyst from the regenerator enter the first fluidized bed reactor for catalytic cracking reaction. Optionally, the reaction products are contacted with the introduced supplementary catalyst and the reaction continues.

[0092] (2) The second raw material is introduced from the downstream feed section of the second fluidized reactor and comes into contact with the reduced catalyst mixture from the catalyst reducer to undergo a cracking reaction. The catalyst mixture includes regenerated catalyst and fresh catalyst.

[0093] (3) The reaction products and the catalyst to be generated in the first fluidized bed reactor and the second fluidized bed reactor enter the oil-solid separation equipment for gas-solid separation, and the reaction oil and gas and the catalyst to be generated are separated. The separated reaction oil and gas are further separated to obtain ethylene, propylene, difficult-to-convert components and other products.

[0094] (4) The separated raw catalyst is stripped and then enters the coking unit. After being mixed with the regenerated catalyst from the regenerator and heated, it comes into contact with the raw coking raw material to produce a coking reaction, thus obtaining the raw catalyst with coke.

[0095] (5) The catalyst with coke enters the regenerator and reacts with oxygen-containing gas to produce a carbonization reaction. The first part of the regenerated catalyst is returned to the coke generator for reaction recycling. The second part of the regenerated catalyst is returned to the first fluidized bed reactor for reaction recycling. The third part of the regenerated catalyst enters the reducer and is mixed with the fresh catalyst. Under the action of the reducing medium, a reduction reaction occurs and energy is released. The catalyst mixture after reduction enters the second fluidized bed reactor for reaction recycling.

[0096] The first raw material is selected from one or more of crude oil, mineral oil, and synthetic oil;

[0097] The second feedstock is self-produced by the equipment and / or other difficult-to-convert components, wherein the difficult-to-convert components are light hydrocarbons and / or light distillate oils.

[0098] The present application will be further described below with reference to the preferred embodiments shown in the accompanying drawings, but this does not limit the present application.

[0099] Figure 1 A preferred embodiment of the catalytic cracking method of this application is provided, wherein the first fluidized bed reactor 100 is provided with a pre-lifting medium inlet 101, a catalyst inlet 103, and a crude oil inlet 102 from bottom to top. The second fluidized bed reactor 300 is provided with a pre-lifting section 309, a first feed section 311, a second feed section 312, a main reaction section 310, and an outlet section 308.

[0100] The pre-lifting medium enters the bottom of the first fluidized bed reactor 100 through pipeline 101. The lifting medium can be dry gas, water vapor, or a mixture thereof. It mixes with the hot regeneration catalyst from the regeneration inclined tube 403 and moves upward. The reaction feedstock, such as preheated crude oil and atomized steam, is injected into the lower part of the first fluidized bed reactor 100 through feed pipeline 102, where it mixes and contacts with the high-temperature regeneration catalyst and undergoes catalytic cracking reaction.

[0101] The hot regenerated catalyst from the regenerated inclined tube 406 and the fresh catalyst from the pipeline 504 enter the reducer 500. Under the action of the reduction medium introduced through the pipeline 501, the metal oxide on the catalyst undergoes a reduction reaction, releasing energy. The high-temperature regenerated catalyst enters the bottom of the second fluidized bed reactor through the pipeline 503. Under the lifting action of the pre-lifting medium from the pipeline 301, it moves upward and enters the first feed section of the second fluidized bed reactor.

[0102] Some of the difficult-to-convert raw materials and atomized steam are injected into the lower part of the first feed section 311 of the second fluidized bed reactor through feed line 303, where they mix and come into contact with the existing catalyst in the catalytic cracking reactor. The oil-agent mixture moves upward and, optionally, mixes with some of the difficult-to-convert raw materials injected through line 304 and enters the upper part of the second feed section 312. Alternatively, some of the difficult-to-convert raw materials enter the lower part of the second feed section 312 through line 305. The oil-agent mixture enters the main reaction section 310 and undergoes a full cracking reaction.

[0103] The catalyst-to-oil ratio and activity of the catalyst in the first feed section 311 and the second feed section 312 of the second fluidized bed reactor can be adjusted according to the reaction requirements by regulating the flow rates of the external catalyst circulation line 306 and the catalyst outlet line 307.

[0104] The reaction oil and gas generated by the catalytic cracking reaction in the first and second fluidized bed reactors, along with the catalyst to be generated, flow upwards and enter the oil-catalyst separation device 204 (such as a cyclone separator) through outlets 104 and 308, respectively, for gas-solid separation. The separated reaction oil and gas are led out through the gas collecting chamber 205 and the large oil and gas pipe 206 to enter the subsequent separation system; the separated catalyst to be generated enters the lower stripping section 201 of the settling tank 200, and after being stripped by the stripping medium from pipeline 202, it enters the coking unit 700 through the catalyst to be generated inclined pipe 203.

[0105] The fluidizing medium enters the coking unit 700 from the bottom of the coking unit 700 through the inlet 701 and the gas distributor 702. The fluidizing medium can be nitrogen, water vapor, or a mixture thereof. High-temperature regenerated catalyst from external catalyst circulation pipe 703 enters the lower part of coking unit 700, mixes with fluidizing gas and moves upward, contacts the spent catalyst from spent catalyst inlet 203 and continues to move upward, contacts supplementary fuel oil from fuel oil inlet 704 and undergoes coking reaction; catalyst with coke flows upward, enters regenerator 400 through catalyst distributor 705, contacts oxygen-containing gas injected through oxygen-containing gas inlet 401 and main air distributor 402 and undergoes complete combustion reaction, completely releasing heat, the regenerated catalyst is sent out of regenerator through regenerated catalyst outlet 406, part of the regenerated catalyst is supplied to the first fluidized bed reactor for recycling through pipeline 403, part of the regenerated catalyst is injected into the reducer through pipeline 406, and after reduction, it is supplied to the second fluidized bed reactor; the regenerated flue gas is separated from the entrained catalyst by cyclone separator 404 and enters energy recovery system through pipeline 405.

[0106] The crude oil for which the process method provided in this application is applicable is selected from one or more of crude oil, mineral oil, and synthetic oil. The crude oil is a full-range crude oil from a conventional source, the mineral oil is selected from one or more of coal liquefaction oil, oil sands oil, and shale oil, and the synthetic oil is a distillate oil obtained by FT synthesis of coal, natural gas, or bitumen.

[0107] In this application, the difficult-to-convert component is light hydrocarbon or light distillate oil from this device or from external sources.

[0108] In one embodiment, the crude oil is a full-fraction crude oil;

[0109] The mineral oil is selected from one or more of coal liquefaction oil, oil sands oil, and shale oil; and / or

[0110] The synthetic oil is a distillate obtained by FT synthesis of coal, natural gas, or bitumen.

[0111] In one embodiment, the light hydrocarbons include gaseous hydrocarbon products rich in C4 fractions produced by the device itself and / or gaseous hydrocarbons rich in C4 fractions produced by other devices, wherein the C4 olefin content in the gaseous hydrocarbons rich in C4 fractions is greater than 50% by weight.

[0112] Preferably, the difficult-to-convert component is a C4 fraction produced by the device itself.

[0113] In one embodiment, the light hydrocarbons in the difficult-to-convert component are C4 components. These C4 components refer to low-molecular-weight hydrocarbons existing in gaseous form at room temperature and pressure, with C4 fractions as the main component. They include alkanes, alkenes, and alkynes with four carbon atoms in their molecules. This includes gaseous hydrocarbon products rich in C4 fractions produced by the apparatus of this invention, and may also include gaseous hydrocarbons rich in C4 fractions produced by processes in other apparatuses, with the C4 fraction produced by the apparatus of this invention being preferred. The C4 hydrocarbons are preferably C4 fractions rich in olefins, wherein the content of C4 olefins is greater than 50% by weight, preferably greater than 60% by weight, and most preferably greater than 70% by weight.

[0114] In one embodiment, the light distillate oil comprises light distillate oil produced by the unit with a final boiling point of less than 280-350°C and optionally one or more of the following fractions:

[0115] Other primary processing units produce straight-run naphtha, straight-run kerosene, and straight-run diesel oil;

[0116] Other secondary processed oils include topping oil, residue oil, hydrocracked light naphtha, pentane oil, coking gasoline, Fischer-Tropsch synthetic oil, catalytic cracked light gasoline, hydrotreated gasoline, and hydrotreated diesel.

[0117] In one embodiment, the first fluidizing reactor is selected from one or more of the following in series: a turbulent bed reactor, a fast bed reactor, and a dilute phase transport bed reactor; and / or

[0118] The second fluidized bed reactor is a dilute phase transport bed reactor.

[0119] In one embodiment, the first fluidization reactor is selected from one or a combination of several of turbulent bed, fast bed, and dilute phase transport bed. It can be one or a combination of two reactors in series: those with constant linear velocity, constant diameter, variable diameter, upward transport line, and downward transport line. To ensure sufficient reaction of the feedstock oil and depending on different target product quality requirements, there can be 2-8 reaction zones, preferably 2-3. The gas velocity in the turbulent bed and fast bed reactors is 0.1 m / s to 2 m / s, and the gas velocity in the dilute phase transport bed is 2 m / s to 20 m / s. The second fluidization reactor is selected from a dilute phase transport bed reactor, which can be a conventional constant diameter reactor or a reactor with various variable diameter configurations.

[0120] In one embodiment, the catalytic cracking reaction conditions in the first fluidized bed reactor are as follows:

[0121] The reaction temperature is 510-650℃;

[0122] The reaction time is 1-20 seconds;

[0123] The weight ratio of catalyst to feedstock is (3-50):1; and / or

[0124] The reaction pressure is 130-450 kPa;

[0125] Preferably, the first raw material is preheated and steam atomized before entering the first fluidized bed reactor. The preheating temperature is 180-350℃ and the water-to-oil weight ratio is (0.03-0.8):1.

[0126] In this application, the catalytic cracking reaction temperature of the first fluidized bed reactor refers to the reactor outlet temperature.

[0127] In one embodiment, the second fluidized bed reactor is provided with a main reaction section and one or more feed sections for difficult-to-convert components;

[0128] Preferably, the one or more feed sections for the recalcitrant components are each independently located in the middle to upstream of the second fluidized bed reactor; and / or

[0129] Preferably, the catalyst density in each of the feed sections for the recalcitrant components is 120-290 kg / m³. 3 .

[0130] In one embodiment, the second fluidized bed reactor is provided with one or more, such as one, two or more, feed sections for recalcitrant feedstocks, which may be independently located in the lower part of the second fluidized bed reactor. More preferably, the recalcitrant feedstock inlets are each independently located in the middle to upstream of the catalytic cracking reactor.

[0131] In one embodiment, the light hydrocarbons and light distillate oils of the difficult-to-convert components can be introduced into the second fluidized bed reactor at the same or different locations in the same feed section, or they can be introduced into the second fluidized bed reactor at different feed sections. Preferably, the light hydrocarbons are introduced into the second fluidized bed reactor at one or more locations downstream of the light distillate oil introduction location.

[0132] In one embodiment, the catalytic cracking reaction conditions in the second fluidized bed reactor are as follows:

[0133] The reaction temperature is 580-75℃;

[0134] The reaction time is 0.05-5 seconds; and / or

[0135] The weight ratio of catalyst to feedstock oil is (1-50):1;

[0136] Preferably, the second raw material is introduced into the second fluidized bed reactor after being atomized by steam, and the water-to-oil weight ratio is (0.03-0.5):1.

[0137] In one embodiment, the weight ratio of fresh catalyst to regenerated catalyst in the catalyst reducer is (0.005-0.3):1.

[0138] In one embodiment, the reduction temperature in the catalyst reducer is 550-700°C;

[0139] The restoration time is 2-20 minutes; and / or

[0140] The reducing medium is refinery dry gas and / or small molecule alkanes, wherein the small molecule alkanes are C1-C3 alkanes, preferably refinery dry gas.

[0141] In one embodiment, the outlet temperature of the coking device is 550-650°C, and / or the linear velocity is 1.2-2.2 m / s.

[0142] Preferably, the atomizing medium of the coking device is nitrogen, and the mass ratio of the atomizing medium to the combustion oil is 1:1 to 1:100.

[0143] In one embodiment, the temperature inside the regenerator is 550-750°C, more preferably 600-730°C, and even more preferably 650-700°C; the apparent linear velocity of the gas is 0.3-3 m / s, preferably 0.5-2.5 m / s, more preferably 0.6-1.2 m / s, and the average residence time of the catalyst to be generated is 0.6-8 minutes, preferably 0.8-6 minutes, and more preferably 1-5 minutes.

[0144] In one embodiment, the catalyst comprises 0.01-5 wt%, preferably 0.005-2 wt%, of a metal oxide, wherein the metal oxide is selected from one or more of the following: tin, cobalt, iron, molybdenum, manganese, copper, barium, and chromium.

[0145] Preferably, based on the dry weight of the catalyst, the catalyst comprises:

[0146] 0-70 parts by weight, preferably 5-60 parts by weight, more preferably 10-50 parts by weight of clay,

[0147] 5-99 parts by weight, preferably 10-80 parts by weight, more preferably 20-70 parts by weight of adhesive,

[0148] 1-60 parts by weight, preferably 5-45 parts by weight, more preferably 10-40 parts by weight of zeolite, and

[0149] 0.001-5 parts by weight, preferably 0.005-2 parts by weight, of a metal oxide.

[0150] And the total weight of the catalyst is 100 parts by weight;

[0151] The adhesive is an inorganic oxide adhesive, preferably silicon dioxide and / or aluminum oxide;

[0152] The zeolite includes mesoporous zeolite and optional macroporous zeolite. The mesoporous zeolite is ZSM series zeolite and / or ZRP zeolite. The macroporous zeolite is selected from one or more of rare earth Y-type zeolite, rare earth hydrogen Y-type zeolite, ultrastable Y-type zeolite and high silica Y-type zeolite. Preferably, the mesoporous zeolite accounts for 5-100% of the total weight of the zeolite, more preferably 50-90% by weight, and more preferably 20-50% by weight.

[0153] The clay is preferably kaolin and / or hydrous kaolin.

[0154] In this application, the clay is used as a matrix (i.e., a carrier), and inorganic oxides are used as a binder.

[0155] The terms "mesoporous zeolite" and "macroporous zeolite" follow the conventional definitions in the art, namely, the average pore size of mesoporous zeolite is about 0.5-0.6 nm, and the average pore size of macroporous zeolite is about 0.7-1.0 nm.

[0156] As an example, the macroporous zeolite may be selected from one or more of rare earth Y (REY) type zeolite, rare earth hydrogen Y (REHY) type zeolite, ultrastable Y type zeolite obtained by different methods, and high-silica Y type zeolite. The mesoporous zeolite may be selected from zeolites with an MFI structure, such as ZSM series zeolites and / or ZRP zeolite. Optionally, the above-mentioned mesoporous zeolites may be modified with non-metallic elements such as phosphorus and / or transition metal elements such as iron, cobalt, and nickel. A more detailed description of ZRP zeolite can be found in US Patent 5,232,675A. The ZSM series zeolites are preferably selected from one or more mixtures of ZSM-5, ZSM-11, ZSM-12, ZSM-23, ZSM-35, ZSM-38, ZSM-48, and other zeolites with similar structures. A more detailed description of ZSM-5 can be found in US Patent 3,702,886A.

[0157] In the method provided by this invention, the catalyst preparation method adopts a conventional method for preparing catalytic cracking catalysts, which is well known to those skilled in the art. The metal loaded onto the catalyst can be achieved by impregnation or slurry mixing, with impregnation being preferred; these methods are well known to those skilled in the art.

[0158] According to this application, the equipment for separating the reaction products from the catalyst is well known to those skilled in the art. For example, the oil separation equipment may include a cyclone separator, a settling tank, and a stripper. Methods or equipment for further separating the reaction oil and gas to obtain dry gas, liquefied petroleum gas (LPG), light distillate oil from difficult-to-convert components, and cracked heavy oil are also well known to those skilled in the art. For example, the reaction product separation equipment may be a fractionating tower. The dry gas and LPG can be further separated using conventional separation methods in the art to obtain target products such as ethylene and propylene, and C4 fractions.

[0159] This invention incorporates a catalyst reducer in the reaction system. The catalyst portion regenerated by the regenerator enters the reducer and mixes with the fresh catalyst. Under the action of a reducing medium (e.g., refinery dry gas and / or small molecule alkanes), the variable valence metal oxides in the mixed catalyst are reduced and release energy. The reduced and regenerated catalyst carries the energy into the second reactor to participate in the reaction, thereby providing heat for the catalytic cracking reaction of the difficult-to-convert components in the second reactor, solving the problem of high reaction heat demand for the difficult-to-convert components in the second reactor.

[0160] This invention also provides a system for the direct catalytic cracking of crude oil to produce low-carbon olefins, comprising:

[0161] The catalytic cracking reaction unit includes:

[0162] The first fluidized bed reactor is provided with a pre-lifting medium inlet, a regenerated catalyst inlet, a supplementary catalyst inlet, a feedstock oil inlet, and a first oil-agent mixture outlet;

[0163] The second fluidized bed reactor is provided with a pre-lifting section, a feed section, a main reaction section and an outlet section from bottom to top. The bottom of the pre-lifting section is provided with a reduction catalyst inlet and a pre-lifting medium inlet. The feed section is provided with a difficult-to-convert raw material inlet, a circulating catalyst inlet and an optional outgoing catalyst outlet.

[0164] An oil-liquid separation device is connected to both the outlet of the first oil-liquid mixture from the first fluidized bed reactor and the outlet of the second oil-liquid mixture from the second fluidized bed reactor, such that the first oil-liquid mixture from the first fluidized bed reactor and the second oil-liquid mixture from the second fluidized bed reactor are separated into reaction oil gas and catalyst to be generated by the oil-liquid separation device; and

[0165] A settling device is used to settle and collect the catalyst to be generated after being separated by the oil-based separation equipment. A stripping section is provided below the settling device for stripping the catalyst to be generated. The stripping section is provided with a catalyst outlet and a stripping medium inlet.

[0166] Catalyst regeneration unit, including

[0167] A coking unit is used to bring the catalyst to be generated separated from the catalytic cracking reaction unit into contact with the coking raw material to produce a coking reaction and obtain a catalyst with coke. It is provided with a catalyst inlet, a fluidized medium inlet, a coking raw material inlet, a first gas distributor and a coking catalyst outlet. The catalyst inlet is in fluid communication with the catalyst outlet of the stripping section of the settling tank.

[0168] The regenerator is provided with a coke catalyst inlet, an oxygen-containing gas inlet, a second gas distributor, a cyclone separator, a regenerated flue gas pipeline, and at least one regenerated catalyst outlet; the coke catalyst inlet of the regenerator is in fluid communication with the coke catalyst outlet of the coke reactor; one regenerated catalyst outlet is connected to the regenerated catalyst inlet of the first fluidized bed reactor for recycling a portion of the regenerated catalyst back to the first fluidized bed reactor.

[0169] A regenerated catalyst circulation pipeline is provided between the coking unit and the regenerator, which is used to allow a portion of the regenerated catalyst to enter the coking unit and mix with the catalyst to be generated to jointly react with the coking raw material in the coking reaction.

[0170] A catalyst reducer is provided with a regenerated catalyst inlet, a fresh catalyst inlet, a reduced catalyst outlet, and a reduced medium inlet; the regenerated catalyst inlet of the catalyst reducer is connected to a regenerated catalyst outlet, so that a portion of the regenerated catalyst from the regenerator is reduced in the catalyst reducer; the reduced catalyst outlet of the catalyst reducer is in fluid communication with the reduced catalyst inlet of a second fluidized bed reactor, so that the reduced catalyst is circulated back to the second fluidized bed reactor.

[0171] The catalyst reducer is arranged in parallel or coaxially with the second fluidized bed reactor, and the coke generator is arranged coaxially with the regenerator.

[0172] In one embodiment, the connection port of the regeneration catalyst circulation pipeline on the coking unit is located at a distance of 5% to 10% of the height of the coking unit from the bottom of the coking unit; and / or

[0173] The distance between the raw coke inlet and the bottom of the coker is 0% to 50% of the height of the coker.

[0174] In this application, the coking unit may be provided with one or more, such as one, two, or more fuel oil inlets. These fuel oil inlets may be independently located at the outlet end of the coking unit or at the bottom of the coking unit. Preferably, each fuel oil inlet is independently located in the middle to upper part of the coking unit. Preferably, the distance between each fuel oil inlet and the bottom of the coking unit is independently 20% to 50% of the coking unit height. The fuel oil may include straight-run distillate or secondary processed distillate. Preferably, the secondary processed distillate may be selected from one or more blends of catalytic cracking diesel, catalytic cracking slurry oil, coking gasoline, coking diesel, and coking wax oil.

[0175] In one embodiment, the fluidizing medium of the coking device enters the coking device through a first gas distributor located at the bottom.

[0176] According to this application, the first gas distributor can be a main air distributor well known to those skilled in the art. For example, the main air distributor can be a distribution plate or a distribution pipe. Preferably, the distribution pipe is an annular distribution pipe or a tree-shaped distribution pipe.

[0177] In this application, a catalyst distribution plate can be installed at the bottom of the catalyst inlet of the regenerator, for example, at the outlet end of the coking unit. According to this application, the catalyst distribution plate can be one or more of various industrially common types, such as flat, arched, disc-shaped, annular, and umbrella-shaped plates. Using a catalyst distribution plate helps to ensure uniform concentration of the catalyst in contact with the oxygen-containing gas along the axial direction of the regenerator for the coking reaction, improving coking efficiency and reducing the occurrence of localized hot spots in the catalyst bed.

[0178] By setting up a coking unit, the injected fuel oil is mixed with the catalyst under low temperature and oxygen-free fluidization conditions to form coke. The catalyst with coke attached is back-mixed in the coking unit to make the coke evenly distributed on the catalyst, which helps to achieve a uniform temperature distribution on the catalyst surface.

[0179] In one embodiment, a second gas distributor is provided at the bottom of the regenerator, so that oxygen-containing gas injected through the oxygen-containing gas inlet enters the regenerator through the second gas distributor. According to this application, the second gas distributor can be a main air distributor well known to those skilled in the art. For example, the main air distributor can be a distribution plate or a distribution pipe. Preferably, the distribution pipe is an annular distribution pipe or a dendritic distribution pipe.

[0180] In one embodiment, the second fluidized bed reactor includes two feed sections connected in sequence. The first feed section is connected to the pre-lifting section, and the second feed section is connected to the main reaction section. An external catalyst circulation pipeline connecting the two feed sections is provided between the first feed section and the second feed section.

[0181] Preferably, the distance from the connection port of the external catalyst circulation pipe on the first feed section to the bottom of the first feed section is 0 to 10% of the height of the second feed section; and / or the distance from the outlet of the catalyst on the second feed section to the bottom of the second feed section is 5% to 20% of the height of the second feed section.

[0182] The height of the second feeding section is H1 as shown in the figure.

[0183] Example

[0184] The following embodiments will further illustrate this application, but do not limit this application.

[0185] The feedstock used in the following examples and comparative examples was Kuwaiti crude oil, the properties of which are shown in Table 1. The catalyst used was a commercial catalytic cracking catalyst purchased from the Catalyst Division of China Petroleum & Chemical Corporation (Sinopec), with the trade name DMMC-1. The examples used a DMMC-1 catalyst containing CuO, with CuO accounting for 1.0% by weight of the total catalyst weight.

[0186] Example 1

[0187] Using the feedstock oils shown in Table 1 and the CuO-containing DMMC-1 catalyst, in Figure 1 The experiment was conducted on the medium-sized apparatus shown, in which the reactor structure is as follows:

[0188] Both the first and second fluidized bed reactors are riser reactors of equal diameter. The first fluidized bed reactor has a total height of 7 meters and an inner diameter of 0.3 meters; the second fluidized bed reactor has a height of 5 meters and an inner diameter of 0.2 meters. Two feed sections are located at the bottom, each with a height of 0.2 meters and an inner diameter of 0.3 meters. The first feed section has one feed inlet, and the second feed section has two feed inlets. The coking unit has an inner diameter of 0.3 meters and a height of 2 meters. The distance from the coking feed inlet 704 to the bottom of the coking unit is 30% of the coking unit's height. The outlet of the coking unit is directly connected to the bottom opening of the regenerator, and a catalyst distributor is installed at the outlet.

[0189] The hot-regenerated catalyst in the first regeneration inclined tube 403 enters the lower part of the first fluidized bed reactor and moves upward under the action of the pre-lifting medium. Preheated crude oil and atomized steam are injected into the lower part of the first fluidized bed reactor through the first feed line 102, with a water-to-oil weight ratio of 0.2:1. They mix and contact with the existing catalyst in the catalytic cracking reactor and carry out a catalytic cracking reaction to generate the first reaction product and the catalyst to be generated.

[0190] The hot-regenerated catalyst from the second regeneration inclined tube 406 and the fresh catalyst from the fresh catalyst line 504 enter the catalyst reducer 500. Under the action of the reducing medium injected through the reducing medium line 501, a reduction reaction occurs. The reduced high-temperature regenerated catalyst is injected into the pre-lifting section at the bottom of the second flow reactor through the reducing catalyst line 503. Under the action of the pre-lifting medium injected through the second pre-lifting medium line 301, it moves upward. The C4 fraction from the fractionation unit and the light distillate oil with a distillation range of less than 320°C enter the bottom of the first feed section through the second feed line 303. The water-oil weight ratio is 0.2:1. They come into contact with the existing catalyst in the reactor and move upward, entering the main reaction section 310 of the second fluidized bed reactor and undergoing a catalytic cracking reaction to generate the second reaction product and the catalyst to be generated.

[0191] The first and second reaction products and the catalyst to be generated enter the oil-solid separation device 204, such as a cyclone separator, for gas-solid separation. The resulting reaction oil and gas are led out through the gas collection chamber 205 and the large oil and gas pipe 206 and enter the subsequent separation system. The catalyst containing coke obtained from the separation enters the lower part of the settling tank 200 and enters the coking tank 700 through the inclined tube 203.

[0192] Nitrogen gas is introduced into the bottom of the coking unit 700, where it mixes sequentially with the regenerated catalyst and the catalyst to be regenerated, causing the catalyst to be regenerated to heat up. The coking raw material, atomized by nitrogen, is injected into the coking unit, where it comes into contact with the internal flow and undergoes a coking reaction. The catalyst containing coke enters the regenerator, where it comes into contact with air and undergoes a complete combustion reaction. Part of the regenerated catalyst is returned to the first fluidized bed reactor for reaction recycling, and part of the regenerated catalyst enters the reducer. The regenerated catalyst after reduction is returned to the second fluidized bed reactor for reaction recycling. The regenerated flue gas enters the energy recovery system through the regenerated flue gas recovery pipeline 405.

[0193] Operating conditions and product distribution are listed in Tables 2 and 3. As can be seen from Table 3, the ethylene yield in this embodiment reached 10.01% by weight, the propylene yield reached 24.72% by weight, and the total yield of low-carbon olefins and light aromatics was 49.09%.

[0194] Example 2

[0195] Using the feedstock oils shown in Table 1 and the CuO-containing DMMC-1 catalyst, in Figure 1 The experiment was conducted on the medium-sized apparatus shown, in which the reactor structure is as follows:

[0196] Both the first and second fluidized bed reactors are riser reactors of equal diameter. The first fluidized bed reactor has a total height of 7 meters and an inner diameter of 0.3 meters; the second fluidized bed reactor has a height of 5 meters and an inner diameter of 0.2 meters. Two feed sections are located at the bottom, each with a height of 0.2 meters and an inner diameter of 0.3 meters. The first feed section has one feed inlet, and the second feed section has two feed inlets. The coking unit has an inner diameter of 0.3 meters and a height of 2 meters. The distance from the coking feed inlet 704 to the bottom of the coking unit is 30% of the coking unit's height. The outlet of the coking unit is directly connected to the bottom opening of the regenerator, and a catalyst distributor is installed at the outlet.

[0197] The hot-regenerated catalyst in the first regeneration inclined tube 403 enters the lower part of the first fluidized bed reactor and moves upward under the action of the pre-lifting medium. Preheated crude oil and atomized steam are injected into the lower part of the first fluidized bed reactor through the first feed line 102, with a water-to-oil weight ratio of 0.2:1. They mix and contact with the existing catalyst in the catalytic cracking reactor and carry out a catalytic cracking reaction to generate the first reaction product and the catalyst to be generated.

[0198] The hot-regenerated catalyst from the second regeneration inclined tube 406 and the fresh catalyst from the fresh catalyst line 504 enter the catalyst reducer 500. Under the action of the reducing medium injected through the reducing medium line 501, a reduction reaction occurs. The reduced high-temperature regenerated catalyst is injected into the pre-lifting section at the bottom of the second fluidized bed reactor through the reducing catalyst line 503. Under the action of the pre-lifting medium injected through the second pre-lifting medium line 301, it moves upward. Light distillate oil with a distillation range of less than 320°C enters the bottom of the first feed section through the second feed line 303. The water-oil weight ratio is 0.2:1. It contacts the existing catalyst in the reactor and moves upward. C4 fraction enters the bottom of the second feed section through the third feed line 304. It contacts the existing catalyst in the reactor and moves upward. It enters the main reaction section 310 of the second fluidized bed reactor and undergoes a catalytic cracking reaction to generate the second reaction product and the catalyst to be generated.

[0199] The first and second reaction products and the catalyst to be generated enter the oil-solid separation device 204, such as a cyclone separator, for gas-solid separation. The resulting reaction oil and gas are led out through the gas collection chamber 205 and the large oil and gas pipe 206 and enter the subsequent separation system. The catalyst containing coke obtained from the separation enters the lower part of the settling tank 200 and enters the coking tank 700 through the inclined tube 203.

[0200] Nitrogen gas is introduced into the bottom of the coking unit 700, where it mixes sequentially with the regenerated catalyst and the catalyst to be regenerated, causing the catalyst to be regenerated to heat up. The coking raw material, atomized by nitrogen, is injected into the coking unit, where it comes into contact with the internal flow and undergoes a coking reaction. The catalyst containing coke enters the regenerator, where it comes into contact with air and undergoes a complete combustion reaction. Part of the regenerated catalyst is returned to the first fluidized bed reactor for reaction recycling, and part of the regenerated catalyst enters the reducer. The regenerated catalyst after reduction is returned to the second fluidized bed reactor for reaction recycling. The regenerated flue gas enters the energy recovery system through the regenerated flue gas recovery pipeline 405.

[0201] Operating conditions and product distribution are listed in Tables 2 and 3. As can be seen from Table 3, the ethylene yield in this embodiment reached 10.83% by weight, the propylene yield reached 25.65% by weight, and the total yield of low-carbon olefins and light aromatics was 52.24%.

[0202] Comparative Example 1

[0203] Using the feedstock oil and DMMC-2 catalyst shown in Table 1, experiments were conducted on a medium-sized unit. The reactor consisted of a conventional riser reactor (first fluidized bed reactor) and a series fluidized bed reactor (second fluidized bed reactor). Preheated feedstock oil sequentially entered the riser reaction zone and the fluidized bed reactor to contact the catalytic cracking catalyst for catalytic cracking. The post-reaction stream entered subsequent oil-catalyst separation and product separation equipment. The separated regenerated catalyst entered the lower part of the regenerator, where it reacted with air distributed into the regenerator via the main air distributor to undergo a coking reaction. The coked feedstock was injected into the dense phase catalyst bed, where it reacted with the high-temperature air to release heat. The regenerated catalyst was returned to the reactor for recycling. Operating conditions and product distribution are listed in Tables 2 and 3.

[0204] As can be seen from the results in Table 3, the yield of ethylene in this comparative example reached 7.78% by weight, the yield of propylene reached 19.11% by weight, and the total yield of low-carbon olefins and light aromatics was 48.74%.

[0205] The results from the above examples and comparative examples show that when using the catalytic cracking method and system of this application for crude oil catalytic cracking reaction, the yield of low-carbon olefins is significantly improved and the crude oil atom utilization rate is high. When the thermal balance is insufficient, using a coking unit can make the coke combustion environment in the regenerator mild and stable, and the radial and axial catalyst temperatures help maintain the physical and chemical properties of the catalyst.

[0206] The preferred embodiments of this application have been described in detail above. However, this application is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this application, various simple modifications can be made to the technical solution of this application, and these simple modifications all fall within the protection scope of this application.

[0207] It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, this application will not describe the various possible combinations separately.

[0208] Furthermore, various different embodiments of this application can be combined in any way, as long as they do not violate the spirit of this application, they should also be regarded as the content of this application.

[0209] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0210] The present application has been described above with reference to preferred embodiments; however, these embodiments are merely exemplary and illustrative. Various substitutions and modifications can be made to the present application based on these embodiments, all of which fall within the protection scope of the present application.

[0211] Properties of the crude oil used (Table 1)

[0212]

[0213]

[0214] Table 2 Reaction conditions of Examples 1, 2 and Comparative Example 1

[0215]

[0216]

[0217] Table 3 Comparison of reaction results of Examples 1 and 2 and Comparative Example 1

[0218]

[0219]

Claims

1. A method for direct catalytic cracking of crude oil that can achieve thermal equilibrium, comprising: (1) The first raw material and the regenerated catalyst from the regenerator enter the first fluidized bed reactor for catalytic cracking reaction. Optionally, the reaction products come into contact with the introduced supplementary catalyst and continue to react. (2) The second raw material is introduced from the downstream feed section of the second fluidized reactor and comes into contact with the reduced catalyst mixture from the catalyst reducer to undergo a cracking reaction. The catalyst mixture includes regenerated catalyst and fresh catalyst. (3) The reaction products of the first fluidized bed reactor and the catalyst to be generated are fed into the oil-solid separation equipment for gas-solid separation, and the reaction oil and gas and the catalyst to be generated are separated. The separated reaction oil and gas are further separated to obtain ethylene, propylene, difficult-to-convert components and other products. (4) The separated raw catalyst is stripped and then enters the coking unit. After being mixed with the regenerated catalyst from the regenerator and heated, it comes into contact with the raw coking raw material to produce a coking reaction, thus obtaining the raw catalyst with coke. (5) The catalyst with coke enters the regenerator and reacts with oxygen-containing gas to produce a carbonization reaction. The first part of the regenerated catalyst is returned to the coke generator for reaction recycling. The second part of the regenerated catalyst is returned to the first fluidized bed reactor for reaction recycling. The third part of the regenerated catalyst enters the reducer and is mixed with the fresh catalyst. Under the action of the reducing medium, a reduction reaction occurs and energy is released. The catalyst mixture after reduction enters the second fluidized bed reactor for reaction recycling. The first raw material is selected from one or more of crude oil, mineral oil, and synthetic oil; The second feedstock is self-produced by the unit and / or other difficult-to-convert components, wherein the difficult-to-convert components are light hydrocarbons and / or light distillate oils; The catalyst comprises 0.001-5 wt% of a metal oxide, wherein the metal in the metal oxide is selected from one or more of the following: tin, cobalt, iron, molybdenum, manganese, copper, barium, and chromium.

2. The method according to claim 1, characterized in that, The crude oil in question is a full-fraction crude oil; The mineral oil is selected from one or more of coal liquefaction oil, oil sands oil, and shale oil; and / or The synthetic oil is a distillate obtained by FT synthesis of coal, natural gas, or bitumen.

3. The method according to claim 1, characterized in that, The light hydrocarbons include gaseous hydrocarbon products rich in C4 fractions produced by the unit itself and / or gaseous hydrocarbons rich in C4 fractions produced by other units, wherein the C4 olefin content in the gaseous hydrocarbons rich in C4 fractions is greater than 50% by weight.

4. The method according to claim 3, characterized in that, The difficult-to-convert component is the C4 fraction produced by the unit itself.

5. The method according to claim 1, characterized in that, The light distillate oil includes light distillate oil produced by the unit with a final boiling point of less than 280-350°C and optionally one or more of the following fractions: Other primary processing units produce straight-run naphtha, straight-run kerosene, and straight-run diesel oil; Other secondary processed oils include topping oil, residue oil, hydrocracked light naphtha, pentane oil, coking gasoline, Fischer-Tropsch synthetic oil, catalytic cracked light gasoline, hydrotreated gasoline, and hydrotreated diesel.

6. The method according to claim 1, characterized in that, The first fluidized bed reactor is selected from one or more of the following: turbulent bed reactor, fast bed reactor, and dilute phase transport bed reactor, in series; and / or The second fluidized bed reactor is a dilute phase transport bed reactor.

7. The method according to claim 1, characterized in that, The catalytic cracking reaction conditions in the first fluidized bed reactor are as follows: The reaction temperature is 510-650℃; The reaction time is 1-20 seconds; The weight ratio of catalyst to feedstock is (3-50):1; and / or The reaction pressure is 130-450 kPa.

8. The method according to claim 7, characterized in that, The first raw material is preheated and steam atomized before entering the first fluidized bed reactor. The preheating temperature is 180-350℃ and the water-oil weight ratio is (0.03-0.8):

1.

9. The method according to claim 1, characterized in that, The second fluidized bed reactor is equipped with a main reaction section and one or more feed sections for difficult-to-convert components.

10. The method according to claim 9, characterized in that, The feed sections for one or more recalcitrant components are each independently located in the middle to upstream of the second fluidized bed reactor; and / or The catalyst density in the feed section of each of the aforementioned recalcitrant components is 120-290 kg / m³. 3 .

11. The method according to claim 1, characterized in that, The catalytic cracking reaction conditions in the second fluidized bed reactor are as follows: The reaction temperature is 580-750℃; The reaction time is 0.05-5 seconds; and / or The weight ratio of catalyst to feedstock is (1-50):

1.

12. The method according to claim 11, characterized in that, The second raw material is introduced into the second fluidized bed reactor after being atomized by steam, with a water-to-oil weight ratio of (0.03-0.5):

1.

13. The method according to claim 1, characterized in that, The weight ratio of fresh catalyst to regenerated catalyst in the catalyst reducer is (0.005-0.3):

1.

14. The method according to claim 1, characterized in that, The reduction temperature in the catalyst reducer is 550-700℃; The restoration time is 2-20 minutes; and / or The reducing medium is refinery dry gas and / or small molecule alkanes, wherein the small molecule alkanes are C1-C3 alkanes.

15. The method according to claim 14, characterized in that, The reducing medium is refinery dry gas.

16. The method according to claim 1, characterized in that, The outlet temperature of the coking unit is 550-650℃, and / or the linear velocity is 1.2-2.2 m / s.

17. The method according to claim 1, characterized in that, The catalyst contains 0.005-2 wt% metal oxides.

18. The method according to claim 1, characterized in that, Based on the dry weight of the catalyst, the catalyst comprises: 0-70 parts by weight of clay, 5-99 parts by weight of adhesive, 1-60 parts by weight of zeolite, and 0.001-5 parts by weight of metal oxide, And the total weight of the catalyst is 100 parts by weight; The adhesive is an inorganic oxide adhesive; The zeolite includes mesoporous zeolite and optionally macroporous zeolite, wherein the mesoporous zeolite is ZSM series zeolite and / or ZRP zeolite, and the macroporous zeolite is selected from one or more of rare earth Y-type zeolite, rare earth hydrogen Y-type zeolite, ultrastable Y-type zeolite and high silica Y-type zeolite.

19. The method according to claim 18, characterized in that, Based on the dry weight of the catalyst, the catalyst comprises: 5-60 parts by weight of clay, 10-80 parts by weight of adhesive, 5-45 parts by weight of zeolite, and 0.005-2 parts by weight of metal oxide, The total weight of the catalyst is 100 parts by weight.

20. The method according to claim 19, characterized in that, Based on the dry weight of the catalyst, the catalyst comprises: 10-50 parts by weight of clay, 20-70 parts by weight of adhesive, 10-40 parts by weight of zeolite; and 0.005-2 parts by weight of metal oxide.

21. The method according to claim 18, characterized in that, The adhesive is silicon dioxide and / or aluminum oxide; The clay is kaolin and / or hydrous kaolin.

22. The method according to claim 18, characterized in that, The mesoporous zeolite accounts for 5-100% of the total weight of the zeolite.

23. The method according to claim 22, characterized in that, The mesoporous zeolite accounts for 50-90% of the total weight of the zeolite.

24. The method according to claim 22, characterized in that, The mesoporous zeolite accounts for 20-50% of the total weight of the zeolite.

25. A system for carrying out the method of any one of claims 1-24 to produce low-carbon olefins by direct catalytic cracking of crude oil, comprising: The catalytic cracking reaction unit includes: The first fluidized bed reactor is provided with a pre-lifting medium inlet, a regenerated catalyst inlet, a supplementary catalyst inlet, a feedstock oil inlet, and a first oil-agent mixture outlet; The second fluidized bed reactor is provided with a pre-lifting section, a feed section, a main reaction section and an outlet section from bottom to top. The bottom of the pre-lifting section is provided with a reduction catalyst inlet and a pre-lifting medium inlet. The feed section is provided with a difficult-to-convert raw material inlet, a circulating catalyst inlet and an optional outgoing catalyst outlet. An oil-liquid separation device is connected to both the outlet of the first oil-liquid mixture from the first fluidized bed reactor and the outlet of the second oil-liquid mixture from the second fluidized bed reactor, such that the first oil-liquid mixture from the first fluidized bed reactor and the second oil-liquid mixture from the second fluidized bed reactor are separated into reaction oil gas and catalyst to be generated by the oil-liquid separation device; and A settling device is used to settle and collect the catalyst to be generated after being separated by the oil-based separation equipment. A stripping section is provided below the settling device for stripping the catalyst to be generated. The stripping section is provided with a catalyst outlet and a stripping medium inlet. Catalyst regeneration unit, including A coking unit is used to bring the catalyst to be generated separated from the catalytic cracking reaction unit into contact with the coking raw material to produce a coking reaction and obtain a catalyst with coke. It is provided with a catalyst inlet, a fluidized medium inlet, a coking raw material inlet, a first gas distributor and a coking catalyst outlet. The catalyst inlet is in fluid communication with the catalyst outlet of the stripping section of the settling tank. The regenerator is provided with a coke catalyst inlet, an oxygen-containing gas inlet, a second gas distributor, a cyclone separator, a regenerated flue gas pipeline, and at least one regenerated catalyst outlet; the coke catalyst inlet of the regenerator is in fluid communication with the coke catalyst outlet of the coke reactor; one regenerated catalyst outlet is connected to the regenerated catalyst inlet of the first fluidized bed reactor for recycling a portion of the regenerated catalyst back to the first fluidized bed reactor. A regenerated catalyst circulation pipeline is provided between the coking unit and the regenerator, which is used to allow a portion of the regenerated catalyst to enter the coking unit and mix with the catalyst to be generated to jointly react with the coking raw material in the coking reaction. A catalyst reducer is provided with a regenerated catalyst inlet, a fresh catalyst inlet, a reduced catalyst outlet, and a reduced medium inlet; the regenerated catalyst inlet of the catalyst reducer is connected to a regenerated catalyst outlet, so that a portion of the regenerated catalyst from the regenerator is reduced in the catalyst reducer; the reduced catalyst outlet of the catalyst reducer is in fluid communication with the reduced catalyst inlet of a second fluidized bed reactor, so that the reduced catalyst is circulated back to the second fluidized bed reactor. The catalyst reducer is arranged in parallel or coaxially with the second fluidized bed reactor, and the coke generator is arranged coaxially with the regenerator.

26. The system according to claim 25, characterized in that, The distance from the connection port of the regenerated catalyst circulation pipeline on the coking unit to the bottom of the coking unit is 5% to 10% of the height of the coking unit; and / or The distance between the raw coke inlet and the bottom of the coking unit is 0% to 50% of the height of the coking unit.

27. The system according to claim 25, characterized in that, The second fluidized bed reactor includes two feed sections connected in sequence. The first feed section is connected to the pre-lifting section, and the second feed section is connected to the main reaction section. An external catalyst circulation pipeline connecting the first feed section and the second feed section is provided.

28. The system according to claim 27, characterized in that, The distance from the connection port of the external catalyst circulation pipe on the first feed section to the bottom of the first feed section is 0 to 10% of the height of the second feed section; and / or the distance from the outlet of the catalyst on the second feed section to the bottom of the second feed section is 5% to 20% of the height of the second feed section.

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