A method and system for producing light olefins by direct catalytic cracking of crude oil

Abstract

The application relates to a method and system for producing low-carbon olefins through direct catalytic cracking of crude oil, which comprises the following steps: crude oil is sequentially subjected to catalytic cracking reactions in a first reaction section and a second reaction section of a catalytic cracking reactor; after gas-solid separation of reaction products and spent catalyst, the spent catalyst is sequentially subjected to stripping, supplementary coke making, and coke burning regeneration, and then is returned to the reactor for recycling; the reaction products are separated to obtain ethylene, propylene, difficult-to-convert components and other products, wherein the difficult-to-convert components are further reacted in a second reaction zone of the first reaction section to obtain ethylene and propylene. When the catalytic cracking method and system are used for the catalytic cracking reaction of crude oil, not only is the crude oil processing flow further shortened, and the atom utilization rate of the crude oil is improved, but also the yield of ethylene and propylene is high, and the possible heat balance problem is solved.

Description

Technical Field

[0001] This application relates to the field of petrochemicals, and more specifically, to a catalytic cracking method and system for producing low-carbon olefins from crude oil. Background Technology

[0002] Ethylene, propylene, and BTX (benzene-toluene-xylene) are key basic organic synthesis raw materials with huge demand. They can be used to produce a variety of organic chemical products, including many important high-end organic chemical products, which are closely related to people's basic needs and are an important guarantee for the country's high-quality and sustainable development. Existing technologies for producing propylene and BTX from petroleum are developed based on traditional petroleum refining processes primarily focused on oil production. These processes suffer from problems such as long production lines, low chemical yields, and insignificant economic benefits. The key to solving these problems is to develop critical core technologies that enable the targeted conversion of crude oil hydrocarbon molecules into chemicals. Therefore, in recent years, domestic and international petrochemical companies have been actively exploring technologies for the direct production of chemicals from crude oil, thereby shortening the processing path from crude oil to low-carbon olefins and BTX, reducing energy consumption, and lowering investment.

[0003] WO2005113722A3 and CN200780047937.2 disclose a process method for crude oil direct chemicals, in which crude oil is directly fed into a steam cracking furnace, and light components and heavy components are separated by flash evaporation. The light components (gaseous components) are fed into the steam cracking furnace for cracking, while the heavy components (liquid components) are used as feedstock for the refinery.

[0004] CN 201380015214.X discloses a process for producing olefins and aromatics from crude oil that integrates hydrotreating, steam cracking, and catalytic cracking. After hydrotreating, impurities such as sulfur and high-boiling-point substances are removed from the crude oil. The hydrotreating products are then separated by distillation; the lighter components enter a steam cracking unit, while the heavier components undergo catalytic cracking to maximize olefin production.

[0005] CN201780078199.1 discloses a method and system for converting crude oil into petrochemicals and fuel products by integrating steam cracking and fluid catalytic cracking. The crude oil is separated into straight-run naphtha and lighter fractions, one or more middle distillate fractions, and atmospheric residue. Vacuum distillate is then separated from the atmospheric residue fraction and used as feedstock for catalytic cracking. The lighter fraction is hydrogenated to produce naphtha and diesel fuel oil.

[0006] The aforementioned crude oil processing routes all primarily utilize steam cracking to produce low-carbon olefins. However, steam cracking technology suffers from high energy consumption and limited product flexibility. Researchers are actively developing technologies for producing low-carbon olefins using catalytic cracking.

[0007] CN20181189551.1 and CN201811190135.3 disclose methods for producing low-carbon olefins and aromatics through catalytic cracking of crude oil. These methods include desalting and dehydrating the crude oil, separating it into light and heavy components. The light components (light feedstock) and the heavy components (heavy feedstock) are reacted with a high-temperature catalyst in two separate catalytic cracking reactors under a steam atmosphere to produce low-carbon olefins and aromatics. Alternatively, the light and heavy components can react in different reaction zones within the same reactor.

[0008] CN 201810523356.1 discloses a method for processing crude oil full fractions. The method separates crude oil full fractions to obtain light distillate oil, medium distillate oil and heavy distillate oil. The medium and heavy distillate oils are reacted in a first riser, and the light distillate oil is reacted in a fluidized bed reactor connected in series with the riser. The reaction conditions in the reactor vary depending on the properties of the feedstock.

[0009] Existing crude oil catalytic cracking technologies all employ crude oil distillation for fraction separation and select different catalytic cracking reaction environments based on the performance differences of different fractions. This approach has failed to achieve a truly direct catalytic cracking technology route for crude oil. Summary of the Invention

[0010] The purpose of this application is to provide a method and system for direct catalytic cracking of crude oil full fractions based on current catalytic cracking technology. This method can improve the yield and selectivity of ethylene and propylene production from crude oil catalytic cracking, while also solving the potential problem of insufficient heat in crude oil catalytic cracking reaction.

[0011] A first aspect of the present invention provides a method for producing low-carbon olefins by direct catalytic cracking of crude oil, comprising:

[0012] (1) The first raw material and the regenerated catalyst from the regenerator enter the first reaction zone and the second reaction zone of the first reaction section of the catalytic cracking reactor in sequence to undergo catalytic cracking reaction;

[0013] (2) The reaction products and the catalyst to be generated enter the oil-solid separation equipment through the outlet area for gas-solid separation. The separated reaction oil and gas are led out of the device for further separation to obtain ethylene, propylene, difficult-to-convert components and other products.

[0014] (3) The separated raw catalyst is stripped and then enters the auxiliary regenerator. After being mixed with the regenerated catalyst from the regenerator and heated, it comes into contact with the raw coke feedstock to produce a coking reaction, thus obtaining a raw coke catalyst with coke.

[0015] (4) The raw coke catalyst with coke enters the regenerator and reacts with oxygen-containing gas to produce a complete carbon combustion reaction to obtain a regenerated catalyst. The first part of the regenerated catalyst is returned to the first reaction zone of the first reaction section of the catalytic cracking reactor for recycling, and the second part of the regenerated catalyst is returned to the second reaction zone of the first reaction section at the bottom of the catalytic cracking reactor for use in the reaction.

[0016] (5) The second raw material is fed into the second reaction zone of the first reaction section of the catalytic cracking reactor, and comes into contact with the mixture of regenerated catalyst and fresh catalyst to undergo cracking reaction. The oil mixture generated by the reaction enters the first reaction zone of the first reaction section and mixes with the existing material in the first reaction zone to continue the reaction.

[0017] The first raw material is paraffin-based crude oil, paraffin-intermediate-based crude oil and / or intermediate-paraffin oil crude oil;

[0018] The second raw material is self-produced by the equipment and / or other difficult-to-convert components, wherein the difficult-to-convert components are C4 components and / or light distillate oils with a final boiling point of less than 280-360°C.

[0019] According to the method of the first aspect, the C4 component comprises gaseous hydrocarbons rich in C4 fractions produced by the device itself and / or 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 recalcitrant component includes light distillate oils with a final boiling point of less than 280-360°C produced by the unit itself, 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 processing units produce topping oil, residue oil, hydrocracking light naphtha, pentane oil, coking gasoline, Fischer-Tropsch synthetic oil, catalytic cracking light gasoline, hydrotreated gasoline, and hydrotreated diesel.

[0024] According to the method described in the first aspect, the reaction conditions in the first reaction zone of the first reaction section of the catalytic cracking reactor include:

[0025] The reaction temperature is 550-650℃;

[0026] The reaction time is 0.1-5 seconds; and / or

[0027] The weight ratio of the agent to the oil is (5-30):1;

[0028] Preferably, the first raw material enters the first reaction zone of the first reaction section after preheating and steam atomization. The preheating temperature is 180-350℃, and the water-oil weight ratio is (0.05-0.5):1.

[0029] According to the method described in the first aspect, the reaction conditions of the second reaction section of the catalytic cracking reactor include:

[0030] The reaction temperature is 450-600℃;

[0031] Heavy hourly space velocity is 1-20 hours -1 ; and / or

[0032] According to the method described in the first aspect, the weight ratio of fresh catalyst to regenerated catalyst in the second reaction zone of the first reaction section is 0.01-0.3:1.

[0033] According to the method described in the first aspect, the reaction conditions in the second reaction zone of the first reaction section include:

[0034] The reaction temperature is 600-720℃;

[0035] The reaction time is 0.1-3 seconds; and / or

[0036] The weight ratio of the agent to the oil is (5-50):1;

[0037] Preferably, the second raw material is fed into the second reaction zone of the first reaction section after being atomized by steam, and the water-oil weight ratio is (0.05-0.5):1.

[0038] According to the method described in the first aspect, the outlet temperature of the auxiliary regenerator is 550-650°C;

[0039] Linear velocity of 1.2-2.2 m / s; and / or

[0040] The raw coke feedstock is straight-run distillate oil or secondary processed distillate oil; preferably, the secondary processed distillate oil is selected from one or more of the following: catalytic cracking diesel oil, catalytic cracking slurry oil, coking gasoline, coking diesel oil and coking wax oil.

[0041] A second aspect of the present invention provides a catalytic cracking system, comprising:

[0042] The catalytic cracking reaction unit includes:

[0043] The first reaction section includes a first reaction zone and a second reaction zone. The first reaction zone is provided with an oil inlet, a feedstock oil inlet, a first regenerated catalyst inlet, and a first oil-agent mixture outlet. The second reaction zone is provided with a pre-lifting medium inlet, a second regenerated catalyst inlet, a fresh catalyst inlet, a difficult-to-convert feedstock inlet, and a second oil-agent mixture outlet. The second oil-agent mixture outlet is connected to the oil inlet of the first reaction zone.

[0044] The second reaction section is provided with a first oil mixture inlet, and the first oil mixture outlet extends into the interior of the second reaction section through the first oil mixture inlet;

[0045] An oil-solvent separation device is provided with an oil inlet, a catalyst outlet, and a reaction product outlet. The oil inlet of the oil-solvent separation device is connected to the second reaction section, so that the oil-solvent mixture from the second reaction section is separated into reaction oil gas and catalyst to be generated by the oil-solvent separation device.

[0046] and

[0047] A settling device is provided in the second reaction section for settling and collecting the catalyst to be generated after being separated by the oil-agent separation device. 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.

[0048] A reaction product separation unit, which is connected to an oil separation device, is used to separate the reaction oil and gas separated by the oil separation device.

[0049] The catalyst regeneration unit includes:

[0050] An auxiliary regenerator is used to bring the spent catalyst separated from the catalytic cracking reaction unit into contact with the raw coke feedstock to produce a raw coke catalyst containing coke. It is equipped with a spent catalyst inlet, a fluidized medium inlet, at least one raw coke feedstock inlet, and a raw coke catalyst outlet. The spent catalyst inlet is in fluid communication with the spent catalyst outlet of the settling tank stripping section.

[0051] The regenerator includes a coke catalyst inlet, an oxygen-containing gas inlet, a 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 auxiliary regenerator. One regenerated catalyst outlet is connected to the first regenerated catalyst inlet of the first reaction zone of the first reaction section, for recycling a portion of the regenerated catalyst back to the first reaction zone of the first reaction section. One regenerated catalyst outlet is in fluid communication with the second regenerated catalyst inlet of the second reaction zone of the first reaction section, so that the regenerated catalyst is recycled back to the second reaction zone of the first reaction section.

[0052] A regenerated catalyst circulation pipeline connecting the auxiliary regenerator and the regenerator is provided between the auxiliary regenerator and the regenerator, which is used to allow a portion of the regenerated catalyst to enter the auxiliary regenerator and mix with the catalyst to be generated to jointly react with the coking raw material to form coke.

[0053] According to the system described in the second aspect, the distance between the connection port of the external catalyst circulation pipe on the auxiliary regenerator and the bottom of the auxiliary regenerator is 5% to 10% of the height of the auxiliary regenerator.

[0054] The distance between the raw coke feed inlet and the bottom of the auxiliary regenerator is 20% to 50% of the height of the auxiliary regenerator.

[0055] Compared with the prior art, the method and system of the present invention have the following advantages:

[0056] 1) It can realize direct catalytic cracking of crude oil, reduce the crude oil distillation process, and has a simple process and low operating costs.

[0057] 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 for low-carbon olefins are achieved.

[0058] 3) The light distillate oil reaction zone is upstream of the crude oil reaction zone. After the high-temperature regenerated catalyst passes through the light distillate oil reaction zone, a small amount of carbon deposits on the catalyst passivate the metals on the catalyst. When it comes into contact with crude oil again, it reduces the influence of heavy metals in the crude oil.

[0059] 4) Setting up an auxiliary regenerator can solve the problem of insufficient heat balance when processing high-quality crude oil.

[0060] The catalytic cracking method of this application can directly and efficiently produce chemical feedstocks such as ethylene and propylene from crude oil. This not only further shortens the crude oil processing flow and helps refineries transform, develop, and extend from oil refining to chemical feedstock production, but also improves the economic benefits of refineries. Attached Figure Description

[0061] 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:

[0062] Figure 1 A schematic diagram of a process for producing low-carbon olefins from crude oil by direct catalytic cracking, as provided in this application.

[0063] Explanation of reference numerals in the attached figures:

[0064] I. First reaction zone of the first reaction section; II. Second reaction section; III. Second reaction zone of the first reaction section; 100. Catalytic cracking reactor; 101. Pre-lifting medium pipeline; 102. Fresh catalyst pipeline; 103. First regenerator pipeline; 104. First feed pipeline; 105. Second feed pipeline; 106. Second regenerator pipeline; 107. First reaction section outlet; 200. Settler; 201. Stripping section; 202. Stripping medium; 203. To be... 204. Inclined tube; 205. Oil-agent separation device; 206. Gas collection chamber; 207. Main oil-gas pipe; 300. Auxiliary regenerator; 301. Fluidized medium inlet; 302. First gas distributor; 303. External catalyst circulation pipe; 304. Fuel oil inlet; 305. Catalyst distributor; 400. Regenerator; 401. Oxygen-containing gas inlet; 402. Second gas distributor; 404. Cyclone separator; 405. Regenerated flue gas pipeline; 406. Regenerated catalyst outlet. Detailed Implementation

[0065] 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.

[0066] 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.

[0067] Any specific numerical values ​​disclosed herein (including the endpoints of numerical ranges) are not limited to their exact values, 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 ranges, 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.

[0068] 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).

[0069] 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.

[0070] 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.

[0071] 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.

[0072] This invention provides a method for producing low-carbon olefins through direct catalytic cracking of crude oil, comprising:

[0073] (1) The first raw material and the regenerated catalyst from the regenerator enter the first and second reaction sections of the catalytic cracking reactor in sequence to undergo catalytic cracking reaction;

[0074] (2) The reaction products and the catalyst to be generated enter the oil-solid separation equipment through the outlet area for gas-solid separation. The separated reaction oil and gas are led out of the device for further separation to obtain ethylene, propylene, difficult-to-convert components and other products.

[0075] (3) The separated raw catalyst is stripped and then enters the auxiliary regenerator. After being mixed with the regenerated catalyst from the regenerator and heated, it comes into contact with the raw coke feedstock to produce a coking reaction, thus obtaining a raw coke catalyst with coke.

[0076] (4) The raw coke catalyst with coke enters the regenerator and comes into contact with oxygen-containing gas to undergo a complete carbon combustion reaction to obtain a regenerated catalyst. The first part of the regenerated catalyst is returned to the first reaction section of the catalytic cracking reactor for recycling, and the second part of the regenerated catalyst is returned to the second reaction zone of the first reaction section at the bottom of the catalytic cracking reactor for use in the reaction.

[0077] (5) The second raw material is fed into the second reaction zone of the first reaction section of the catalytic cracking reactor, and comes into contact with the mixture of regenerated catalyst and fresh catalyst to undergo cracking reaction. The oil mixture generated by the reaction enters the first reaction section and mixes with the existing material in the first reaction section to continue the reaction.

[0078] The first raw material is paraffin-based crude oil, paraffin-intermediate-based crude oil and / or intermediate-paraffin oil crude oil;

[0079] The second raw material is self-produced by the equipment and / or other difficult-to-convert components, wherein the difficult-to-convert components are C4 fractions and / or light distillate oils with a final boiling point of less than 280-360°C.

[0080] 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.

[0081] Figure 1A preferred embodiment of the catalytic cracking method of this application is provided, wherein the catalytic cracking reactor 100 comprises, from bottom to top, a second reaction zone III of a first reaction section, a first reaction zone I of the first reaction section, and a second reaction section II. The outlet of the second reaction zone III of the first reaction section is provided with a first feed line 104 for difficult-to-convert raw materials, and the bottom of the first reaction zone I of the first reaction section is provided with a second feed line 105 for raw materials and a second regenerator line 106 for regenerated catalyst.

[0082] The pre-lifting medium enters the bottom of the second reaction zone III of the first reaction section via the pre-lifting medium pipeline 101. The lifting medium can be dry gas, water vapor, or a mixture thereof. Hot regenerated catalyst from the first regenerator pipeline 103 and fresh catalyst from the fresh catalyst pipeline 102 enter the second reaction zone III of the first reaction section. Under the lifting action of the pre-lifting medium, they move upward and mix. Difficult-to-convert feedstock and atomized steam are injected into the lower part of the second reaction zone III of the first reaction section via the first feed pipeline 104, mixing and reacting with the existing catalyst in the catalytic cracking reactor. The resulting oil-catalyst mixture moves upward into the first reaction zone I of the first reaction section. Hot regenerated catalyst from the second regenerator pipeline 106 mixes and moves upward. Reactant feedstocks, such as preheated crude oil and atomized steam, are injected into the bottom of the first reaction zone I of the first reaction section via the second feed pipeline 105, mixing and contacting with the existing oil, gas, and catalyst in the catalytic cracking reactor. The catalytic cracking reaction occurs as the feedstock passes through the first reaction zone I of the first reaction section from bottom to top. The reacting oil and gas and catalyst flow upwards through the outlet 107 of the first reaction section into the second reaction section II, where the catalytic cracking reaction continues. The catalyst containing coke generated from the reaction and the reacting oil and gas enter the oil-solid separation device 204, such as a cyclone separator, for gas-solid separation. The separated reacting oil and gas are led out through the gas collecting chamber 205 and the large oil and gas pipe 206 into the subsequent separation system; the separated coke-containing recycled catalyst enters the lower part of the settling tank 200 and enters the auxiliary regenerator 300 through the recycled inclined pipe 203.

[0083] The fluidizing medium enters the auxiliary regenerator 300 from the bottom of the auxiliary regenerator 300 through the first gas distributor 302 via the fluidizing medium inlet 301. The fluidizing medium can be nitrogen, water vapor, or a mixture thereof. The high-temperature regenerated catalyst from the external catalyst circulation pipe 303 enters the lower part of the auxiliary regenerator 300, mixes with the fluidizing gas and moves upward, contacts the spent catalyst from the spent catalyst inlet inclined pipe 203 and continues to move upward, contacts the supplementary fuel oil from the fuel oil inlet 304 and undergoes a coking reaction; the catalyst with coke flows upward, enters the regenerator 400 through the catalyst distributor 305, contacts the oxygen-containing gas injected through the oxygen-containing gas inlet 401 and the second gas distributor 402 and undergoes a complete combustion reaction, completely releasing heat, the regenerated catalyst is sent out of the regenerator through the regenerated catalyst outlet 406, part of the regenerated catalyst is circulated to the first reaction zone I of the first reaction section through the second regenerator pipeline 106, and part of the regenerated catalyst is used to the second reaction zone III of the first reaction section through the first regenerator pipeline 103; the regenerated flue gas is separated from the entrained catalyst by the cyclone separator 404 and enters the energy recovery system through the regenerated flue gas pipeline 405.

[0084] The catalytic cracking method provided in this application is applicable to crude oils selected from paraffinic crude oils, paraffinic-intermediate crude oils, and intermediate-paraffinic crude oils. In the paraffinic crude oil, either the first critical component or the second critical group is paraffinic; in the paraffinic-intermediate crude oil, the first critical component is paraffinic and the second critical group is intermediate; in the intermediate-paraffinic crude oil, the first critical component is intermediate and the second critical group is paraffinic.

[0085] In one embodiment, the crude oil has a characteristic factor K value of not less than 12.0 and a relative density of 780-900 kg / m³. 3 .

[0086] In this application, the difficult-to-convert component is one of the C4 components or light distillate oils with a final boiling point of less than 280-360°C, or a mixture thereof.

[0087] In one embodiment, the C4 component refers to low-molecular-weight hydrocarbons existing in gaseous form at room temperature and pressure, with C4 fraction as the main component, including alkanes, alkenes, and alkynes with 4 carbon atoms in their molecules. It includes gaseous hydrocarbon products rich in C4 fraction produced by the apparatus of this invention, and may also include gaseous hydrocarbons rich in C4 fraction produced by other apparatus processes, wherein the C4 fraction produced by the apparatus of this invention is 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.

[0088] In one embodiment, the C4 component comprises gaseous hydrocarbons rich in C4 fractions produced by the device itself and / or by other devices, wherein the C4 olefin content in the gaseous hydrocarbons rich in C4 fractions is greater than 50% by weight.

[0089] Preferably, the difficult-to-convert component is a C4 fraction produced by the device itself.

[0090] In one embodiment, the recalcitrant component includes light distillate oils with a final boiling point of less than 280-360°C produced by the unit itself, and optionally one or more of the following fractions:

[0091] Other primary processing units produce straight-run naphtha, straight-run kerosene, and straight-run diesel oil;

[0092] Other secondary processing units produce topping oil, residue oil, hydrocracking light naphtha, pentane oil, coking gasoline, Fischer-Tropsch synthetic oil, catalytic cracking light gasoline, hydrotreated gasoline, and hydrotreated diesel.

[0093] In one embodiment, the reaction conditions in the first reaction zone of the first reaction section of the catalytic cracking reactor include:

[0094] The reaction temperature is 550-650℃;

[0095] The reaction time is 0.1-5 seconds; and / or

[0096] The weight ratio of the agent to the oil is (5-30):1;

[0097] Preferably, the first raw material enters the first reaction zone of the first reaction section after preheating and steam atomization. The preheating temperature is 180-350℃, and the water-oil weight ratio is (0.05-0.5):1.

[0098] In one embodiment, the reaction conditions of the second reaction section of the catalytic cracking reactor include:

[0099] The reaction temperature is 450-600℃;

[0100] Heavy hourly space velocity is 1-20 hours -1 ; and / or

[0101] In one embodiment, the weight ratio of fresh catalyst to regenerated catalyst in the second reaction zone of the first reaction section is 0.01-0.3:1.

[0102] In one embodiment, the reaction conditions in the second reaction zone of the first reaction section include:

[0103] The reaction temperature is 600-720℃;

[0104] The reaction time is 0.1-3 seconds; and / or

[0105] The weight ratio of the agent to the oil is (5-50):1;

[0106] Preferably, the second raw material is fed into the second reaction zone of the first reaction section after being atomized by steam, and the water-oil weight ratio is (0.05-0.5):1.

[0107] In one embodiment, a catalyst mixing zone is provided at the lower part of the second reaction zone of the first reaction section. After the fresh catalyst and the regenerated catalyst are mixed in the catalyst mixing zone, they enter the second reaction zone of the first reaction section.

[0108] In one embodiment, the outlet temperature of the auxiliary regenerator is 550-650°C;

[0109] Linear velocity of 1.2-2.2 m / s; and / or

[0110] The raw coke feedstock is straight-run distillate oil or secondary processed distillate oil; preferably, the secondary processed distillate oil is selected from one or more of the following: catalytic cracking diesel oil, catalytic cracking slurry oil, coking gasoline, coking diesel oil and coking wax oil.

[0111] In this application, the auxiliary regenerator may be provided with one or more, such as one, two, or more fuel oil inlets. These fuel oil (coke feedstock) inlets may be independently located at the outlet of the auxiliary regenerator or at the bottom of the auxiliary regenerator. More preferably, each fuel oil inlet is independently located in the middle to upper reaches of the auxiliary regenerator. 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.

[0112] In one embodiment, the distance from the connection port of the external catalyst circulation pipe on the auxiliary regenerator to the bottom of the auxiliary regenerator is 5% to 10% of the height of the auxiliary regenerator.

[0113] In one embodiment, the outlet temperature of the auxiliary regenerator is 550-650°C.

[0114] In one embodiment, the linear velocity of the auxiliary regenerator is 1.2 m / s to 2.2 m / s, the atomizing medium of the auxiliary regenerator is nitrogen, and the mass ratio of the atomizing medium to the combustion oil is 1:1 to 1:100.

[0115] 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 0.6-1.5 m / s; and the average residence time of the catalyst to be generated is 0.6-83 minutes, preferably 0.8-6 minutes, and more preferably 1-5 minutes.

[0116] In one embodiment, the catalyst used in this invention is based on the dry weight of the catalyst, which comprises 1-50 wt%, preferably 5-45 wt%, more preferably 10-40 wt% of zeolite; 5-99 wt%, preferably 10-80 wt%, more preferably 20-70 wt% of inorganic oxide; and 0-70 wt%, preferably 5-60 wt%, more preferably 10-50 wt% of clay.

[0117] In one embodiment, the zeolite includes mesoporous zeolite and optionally macroporous zeolite, wherein the mesoporous zeolite is selected from ZSM series zeolite, ZRP zeolite, and any combination thereof; and the macroporous zeolite is selected from rare earth Y-type zeolite, rare earth hydrogen Y-type zeolite, ultrastable Y-type zeolite, and high silica Y-type zeolite, and any combination thereof.

[0118] In one embodiment, the mesoporous zeolite accounts for 10-100% by weight, preferably 50-90% by weight, on a dry basis, of the total weight of the zeolite.

[0119] In this application, the terms mesoporous zeolite and macroporous zeolite are defined according to 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.

[0120] 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.

[0121] According to this application, the inorganic oxide, as a binder, is preferably silicon dioxide (SiO2) and / or aluminum oxide (Al2O3). The clay, as a matrix (i.e., carrier), is preferably kaolin and / or hydrous kaolin.

[0122] According to this application, the separation of reaction products from the catalyst to be generated is well known to those skilled in the art. For example, it can be carried out in a settling tank using a cyclone separator. The method of further separating the reaction oil and gas to obtain dry gas, liquefied gas, light distillate oil from difficult-to-convert components, and cracked heavy oil is also well known to those skilled in the art. The dry gas and liquefied gas can be further separated using conventional separation methods in the art to obtain target products such as ethylene and propylene, as well as C4 components.

[0123] The present invention also provides a catalytic cracking system, comprising:

[0124] The catalytic cracking reaction unit includes:

[0125] The first reaction section includes a first reaction zone and a second reaction zone. The first reaction zone is provided with an oil inlet, a feedstock oil inlet, a first regenerated catalyst inlet, and a first oil-agent mixture outlet. The second reaction zone is provided with a pre-lifting medium inlet, a second regenerated catalyst inlet, a fresh catalyst inlet, a difficult-to-convert feedstock inlet, and a second oil-agent mixture outlet. The second oil-agent mixture outlet is connected to the oil inlet of the first reaction zone.

[0126] The second reaction section is provided with a first oil mixture inlet, and the first oil mixture outlet extends into the interior of the second reaction section through the first oil mixture inlet;

[0127] An oil-catalyst separation device is provided with an oil inlet, a catalyst outlet, and a reaction product outlet. The oil inlet of the oil-catalyst separation device is connected to a second reaction section, so that the oil-catalyst mixture from the second reaction section is separated into reaction oil gas and catalyst to be generated by the oil-catalyst separation device; and

[0128] A settling device is provided in the second reaction section for settling and collecting the catalyst to be generated after being separated by the oil-agent separation device. 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.

[0129] A reaction product separation unit, which is connected to an oil separation device, is used to separate the reaction oil and gas separated by the oil separation device.

[0130] The catalyst regeneration unit includes:

[0131] An auxiliary regenerator is used to bring the spent catalyst separated from the catalytic cracking reaction unit into contact with the raw coke feedstock to produce a raw coke catalyst containing coke. It is equipped with a spent catalyst inlet, a fluidized medium inlet, at least one raw coke feedstock inlet, and a raw coke catalyst outlet. The spent catalyst inlet is in fluid communication with the spent catalyst outlet of the settling tank stripping section.

[0132] The regenerator includes a coke catalyst inlet, an oxygen-containing gas inlet, a 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 auxiliary regenerator. One regenerated catalyst outlet is connected to the first regenerated catalyst inlet of the first reaction section for recycling a portion of the regenerated catalyst back to the first reaction section. Another regenerated catalyst outlet is in fluid communication with the second regenerated catalyst inlet of the second reaction zone of the first reaction section, allowing the regenerated catalyst to be recycled back to the second reaction zone of the first reaction section.

[0133] A regenerated catalyst circulation pipeline connecting the auxiliary regenerator and the regenerator is provided between the auxiliary regenerator and the regenerator, which is used to allow a portion of the regenerated catalyst to enter the auxiliary regenerator and mix with the catalyst to be generated to jointly react with the coking raw material to form coke.

[0134] In one embodiment, the distance from the connection port of the external catalyst circulation pipe on the auxiliary regenerator to the bottom of the auxiliary regenerator is 5% to 10% of the height of the auxiliary regenerator.

[0135] The distance between the raw coke feed inlet and the bottom of the auxiliary regenerator is 20% to 50% of the height of the auxiliary regenerator.

[0136] In one embodiment, the fluidizing medium of the auxiliary regenerator enters the auxiliary regenerator through a first gas distributor located at the bottom.

[0137] 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.

[0138] 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 auxiliary regenerator. According to this application, the catalyst distribution plate can be one or more of various types commonly used in industry, 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-enriched 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.

[0139] By setting up an auxiliary regenerator, the injected fuel oil is mixed with the catalyst under low temperature and oxygen-deficient fluidization conditions to form coke. The catalyst with coke attached is back-mixed in the auxiliary regenerator, so that the coke is evenly distributed on the catalyst, which helps to achieve a uniform temperature distribution on the catalyst surface.

[0140] In one embodiment, a second gas distributor is provided at the bottom of the regenerator, so that oxygen-enriched gas injected through the oxygen-enriched 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.

[0141] According to this application, the oil separation equipment and the reaction product separation equipment are 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, while the reaction product separation equipment may be a distillation tower, etc.

[0142] Example

[0143] The following embodiments will further illustrate this application, but do not limit this application.

[0144] The feedstock used in the following examples and comparative examples is crude oil from northern Jiangsu Oilfield, and its properties are shown in Table 1. The catalyst used is a commercial catalytic cracking catalyst purchased from the Catalyst Division of China Petroleum & Chemical Corporation, with the trade name DMMC-2.

[0145] Example 1

[0146] Using the feedstock and DMMC-2 catalyst shown in Table 1, in Figure 1 The experiment was conducted on the medium-sized apparatus shown, in which the reactor structure is as follows:

[0147] The total height of the conventional riser reactor (first reaction section) connected in series with the fluidized bed reactor (second reaction section) is 7 meters. The second reaction zone of the first reaction section is set at the bottom of the first reaction section, with a height of 1 meter and an inner diameter of 0.2 meters.

[0148] The auxiliary regenerator has an inner diameter of 0.3 meters and a height of 2 meters. The fuel oil inlet 304 of the auxiliary regenerator is 30% of the height of the auxiliary regenerator from the bottom of the auxiliary regenerator. The outlet of the auxiliary regenerator is directly connected to the bottom opening of the regenerator, and a catalyst distributor is installed at the outlet.

[0149] The hot regenerated catalyst from the first regenerator line 103 and the fresh catalyst from the fresh catalyst line 102 enter the second reaction zone III of the first reaction section. Under the lifting action of the pre-lifting medium injected through the pre-lifting medium line 101, they move upward. Light distillate oil from the separation system enters the lower part of the reactor through the first feed line 104. The water-oil weight ratio is 0.2:1. It reacts with the mixed catalyst to generate an oil-catalyst mixture.

[0150] The hot-regenerated catalyst from the first regenerator pipeline 103 enters the lower part of the first reaction zone I of the first reaction section, contacts the existing oil-agent mixture in the reactor, and moves upward. Preheated crude oil and atomized steam are injected into the upper part of the first reaction zone I of the first reaction section through the first feed pipeline 104, 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 undergo catalytic cracking reaction as they pass from bottom to top through the first reaction zone I and the second reaction zone II of the first reaction section. The resulting catalyst with coke and the reaction oil and gas enter the oil-agent separation device 204, such as a cyclone separator, for gas-solid separation. The separated reaction oil and gas are led out through the gas collection chamber 205 and the large oil and gas pipe 206 to enter the subsequent separation system. The separated catalyst with coke enters the lower part of the settling tank 200 and enters the auxiliary regenerator 300 through the waiting inclined pipe 203.

[0151] Nitrogen gas is introduced into the bottom of the auxiliary regenerator 300, where it mixes sequentially with the regenerated catalyst and the catalyst to be regenerated, causing the catalyst to heat up. Fuel oil atomized by nitrogen is injected into the auxiliary regenerator, with a mass ratio of atomizing medium to combustion oil of 0.2:1. It comes into contact with the material in the auxiliary regenerator and undergoes a coking reaction. The catalyst containing coke enters the regenerator and undergoes a complete combustion reaction upon contact with air. The regenerated catalyst is divided into two parts: one part is returned to the second reaction zone III of the first reaction section via the first regenerator pipeline 103 for recycling, and the other part is returned to the first reaction zone of the first reaction section via the second regenerator pipeline 106 for recycling. The regenerated flue gas enters the energy recovery system via pipeline 405.

[0152] At the same height, 40% of the axial height of the regenerator, two temperature measuring points are set near the regenerator wall (the angle between the two points and the axial direction is 180 degrees) to measure the mid-temperature at different locations at the same height; a temperature measuring point is set at the top of the regenerator to measure the upper temperature of the regenerator.

[0153] Operating conditions and product distribution are listed in Table 2. As can be seen from Table 2, the ethylene yield in this embodiment reached 7.34% by weight, and the propylene yield reached 28.64% by weight. The temperatures at different locations in the middle of the regenerator were 685°C and 680°C, with a radial temperature difference of only 5°C. The temperature at the top of the regenerator was 693°C, with an axial temperature difference of 8-13°C.

[0154] Comparative Example 1

[0155] Using the feedstock and NCC catalyst shown in Table 1, experiments were conducted on a medium-sized unit. The reactor consisted of a conventional riser reactor (first reaction section) followed by a fluidized bed reactor (second reaction section). Preheated feedstock 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 underwent a coking reaction upon contact with air distributed into the regenerator by the main air distributor. Fuel oil was injected into the dense phase catalyst bed, where it also underwent a coking reaction upon contact with the high-temperature air, releasing heat. The regenerated catalyst was returned to the reactor for recycling. Operating conditions and product distribution are listed in Table 2.

[0156] At the same height, 40% of the axial height of the regenerator, two temperature measuring points are set near the regenerator wall (the angle between the two points and the axial direction is 180 degrees) to measure the mid-temperature at different locations at the same height; a temperature measuring point is set at the top of the regenerator to measure the upper temperature of the regenerator.

[0157] As can be seen from the results in Table 2, the ethylene yield in this comparative example is only 5.10% by weight, and the propylene yield is only 20.43% by weight. The temperatures at different locations in the middle of the regenerator are 666℃ and 724℃, respectively, with a radial temperature difference of 58℃. The temperature at the top of the regenerator is 738℃, with a large axial temperature difference.

[0158] As can be seen from the results of the above examples and comparative examples, when using the catalytic cracking method and system of this application for crude oil catalytic cracking reaction, the crude oil atom utilization rate is high, and the yields of ethylene and propylene are significantly improved. When the heat balance is insufficient, the use of an auxiliary regenerator 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.

[0159] 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.

[0160] 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.

[0161] 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.

[0162] 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.

[0163] 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.

[0164] Properties of the crude oil used (Table 1)

[0165]

[0166] Table 2 Comparison of reaction results between Example 1 and Comparative Example 1

[0167]

[0168]

Claims

1. A method for producing low-carbon olefins through direct catalytic cracking of crude oil, comprising: (1) The first raw material and the regenerated catalyst from the regenerator enter the first reaction zone and the second reaction zone of the first reaction section of the catalytic cracking reactor in sequence to undergo catalytic cracking reaction; (2) The reaction products and the catalyst to be generated enter the oil-solid separation equipment through the outlet area for gas-solid separation. The separated reaction oil and gas are led out of the device for further separation to obtain ethylene, propylene, difficult-to-convert components and other products. (3) The separated raw catalyst is stripped and then enters the auxiliary regenerator. After being mixed with the regenerated catalyst from the regenerator and heated, it comes into contact with the raw coke raw material to produce a raw coke reaction, thus obtaining a raw coke catalyst with coke. (4) The raw coke catalyst with coke enters the regenerator and reacts with oxygen-containing gas to produce a complete carbon combustion reaction to obtain a regenerated catalyst. The first part of the regenerated catalyst is returned to the first reaction zone of the first reaction section of the catalytic cracking reactor for recycling, and the second part of the regenerated catalyst is returned to the second reaction zone of the first reaction section at the bottom of the catalytic cracking reactor for use in the reaction. (5) The second raw material is fed into the second reaction zone of the first reaction section of the catalytic cracking reactor, and comes into contact with the mixture of regenerated catalyst and fresh catalyst to undergo cracking reaction. The oil mixture generated by the reaction enters the first reaction zone of the first reaction section and mixes with the existing material in the first reaction zone to continue the reaction. The first raw material is paraffin-based crude oil, paraffin-intermediate-based crude oil and / or intermediate-paraffin oil crude oil; The second feedstock is self-produced by the equipment and / or other difficult-to-convert components, wherein the difficult-to-convert components are C4 components and / or light distillate oils with a final boiling point of less than 280-360°C; The weight ratio of fresh catalyst to regenerated catalyst in the second reaction zone of the first reaction section is 0.01-0.3:1; The fluidizing medium of the auxiliary regenerator is nitrogen, water vapor, or a mixture thereof.

2. The method according to claim 1, characterized in that, The C4 component includes gaseous hydrocarbons rich in C4 fractions produced by the device itself and / or by other devices, wherein the C4 olefin content in the gaseous hydrocarbons rich in C4 fractions is greater than 50% by weight.

3. The method according to claim 2, characterized in that, The difficult-to-convert component is the C4 fraction produced by the unit itself.

4. The method according to claim 1, characterized in that, The difficult-to-convert components include light distillate oils produced by the unit with a final boiling point of less than 280-360°C.

5. The method according to claim 4, characterized in that, The difficult-to-convert components include 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 processing units produce topping oil, residue oil, hydrocracking light naphtha, pentane oil, coking gasoline, Fischer-Tropsch synthetic oil, catalytic cracking light gasoline, hydrotreated gasoline, and hydrotreated diesel.

6. The method according to claim 1, characterized in that, The reaction conditions in the first reaction zone of the first reaction section of the catalytic cracking reactor include: The reaction temperature is 550-650℃; The reaction time is 0.1-5 seconds; and / or The weight ratio of the agent to the oil is (5-30):

1.

7. The method according to claim 6, characterized in that, The first raw material enters the first reaction zone of the first reaction section after preheating and steam atomization. The preheating temperature is 180-350℃, and the water-oil weight ratio is (0.05-0.5):

1.

8. The method according to claim 1, characterized in that, The reaction conditions in the second reaction section of the catalytic cracking reactor include: The reaction temperature is 450-600℃; and / or Heavy hourly space velocity is 1-20 hours -1 .

9. The method according to claim 1, characterized in that, The reaction conditions in the second reaction zone of the first reaction section include: The reaction temperature is 600-720℃; The reaction time is 0.1-3 seconds; and / or The weight ratio of the agent to the oil is (5-50):

1.

10. The method according to claim 9, characterized in that, The second raw material is atomized by steam and then fed into the second reaction zone of the first reaction section, with a water-to-oil weight ratio of (0.05-0.5):

1.

11. The method according to claim 1, characterized in that, The outlet temperature of the auxiliary regenerator is 550-650℃; Linear velocity of 1.2-2.2 m / s; and / or The raw coke feedstock is straight-run distillate oil or secondary processed distillate oil.

12. The method according to claim 11, characterized in that, The secondary processed distillate oil is selected from one or more of the following: catalytic cracking diesel, catalytic cracking slurry oil, coking gasoline, coking diesel, and coking wax oil.

13. A catalytic cracking system for carrying out the method according to any one of claims 1 to 12, comprising: The catalytic cracking reaction unit includes: The first reaction section includes a first reaction zone and a second reaction zone. The first reaction zone is provided with an oil inlet, a feedstock oil inlet, a first regenerated catalyst inlet, and a first oil-agent mixture outlet. The second reaction zone is provided with a pre-lifting medium inlet, a second regenerated catalyst inlet, a fresh catalyst inlet, a difficult-to-convert feedstock inlet, and a second oil-agent mixture outlet. The second oil-agent mixture outlet is connected to the oil inlet of the first reaction zone. The second reaction section is provided with a first oil mixture inlet, and the first oil mixture outlet extends into the interior of the second reaction section through the first oil mixture inlet; An oil-catalyst separation device is provided with an oil inlet, a catalyst outlet, and a reaction product outlet. The oil inlet of the oil-catalyst separation device is connected to a second reaction section, so that the oil-catalyst mixture from the second reaction section is separated into reaction oil gas and catalyst to be generated by the oil-catalyst separation device; and A settling device is provided in the second reaction section for settling and collecting the catalyst to be generated after being separated by the oil-agent separation device. 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. A reaction product separation unit, which is connected to an oil separation device, is used to separate the reaction oil and gas separated by the oil separation device. The catalyst regeneration unit includes: An auxiliary regenerator is used to bring the spent catalyst separated from the catalytic cracking reaction unit into contact with the raw coke feedstock to produce a raw coke catalyst containing coke. It is equipped with a spent catalyst inlet, a fluidized medium inlet, at least one raw coke feedstock inlet, and a raw coke catalyst outlet. The spent catalyst inlet is in fluid communication with the spent catalyst outlet of the settling tank stripping section. The regenerator includes a coke catalyst inlet, an oxygen-containing gas inlet, a 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 auxiliary regenerator. One regenerated catalyst outlet is connected to the first regenerated catalyst inlet of the first reaction zone of the first reaction section, for recycling a portion of the regenerated catalyst back to the first reaction zone of the first reaction section. One regenerated catalyst outlet is in fluid communication with the second regenerated catalyst inlet of the second reaction zone of the first reaction section, so that the regenerated catalyst is recycled back to the second reaction zone of the first reaction section. A regenerated catalyst circulation pipeline is provided between the auxiliary regenerator and the regenerator, which is used to allow a portion of the regenerated catalyst to enter the auxiliary regenerator and mix with the catalyst to be generated to jointly react with the coking raw material to form coke.

14. The catalytic cracking system according to claim 13, characterized in that, The distance from the connection port of the external catalyst circulation pipe on the auxiliary regenerator to the bottom of the auxiliary regenerator is 5% to 10% of the height of the auxiliary regenerator; The distance between the raw coke feed inlet and the bottom of the auxiliary regenerator is 20% to 50% of the height of the auxiliary regenerator.

Images