Methods and systems for direct catalytic cracking of inferior crude oil

Abstract

This application relates to a method and system for the direct catalytic cracking of low-quality crude oil. The method includes: crude oil undergoing catalytic cracking in a first reactor, and difficult-to-convert components undergoing catalytic cracking in a second reactor. After gas-solid separation, the spent catalyst is stripped and regenerated by coking; part of the regenerated catalyst is returned to the first reactor for recycling, and the remaining part is reduced and activated before being returned to the second reactor for recycling. The reaction products are separated to obtain ethylene, propylene, difficult-to-convert components, and other products. The difficult-to-convert components then undergo further catalytic cracking in the second reactor to obtain ethylene and propylene. When the catalytic cracking method and system of this application are used for crude oil catalytic cracking, ethylene, propylene, 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 field of petrochemicals, and more specifically, to a method and system for the direct catalytic cracking of inferior 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 a process of first distilling crude oil to separate fractions, followed by catalytic cracking reactions. This means that light and heavy fractions enter their respective reaction zones or reactors for catalytic cracking. Different catalytic cracking reaction environments are selected based on the different properties of the fractions, which to some extent helps improve the conversion rate of crude oil molecular cracking. However, this process still involves crude oil flashing and fails to achieve a truly direct catalytic cracking technology route for crude oil. Furthermore, when crude oil quality deteriorates, such as with intermediate-base crude oil, its heavy fractions have a higher density and are less prone to vaporization, resulting in poor catalytic selectivity and high coke yield during the reaction. Summary of the Invention

[0010] The purpose of this application is to provide a method and system for catalytic cracking of crude oil into low-carbon olefins and aromatics, based on current catalytic cracking technology, which helps to improve the yield and selectivity of chemical feedstocks and achieve efficient utilization of crude oil resources.

[0011] A first aspect of the present invention provides a method for direct catalytic cracking of inferior crude oil, the method comprising:

[0012] (1) The first raw material and the regenerated catalyst from the regenerator enter the first reactor for catalytic cracking reaction. Optionally, the reaction products are contacted with the introduced supplementary catalyst and the reaction continues.

[0013] (2) The second raw material is introduced from the downstream feed section of the second reactor and comes into contact with the reduced catalyst mixture from the catalyst reducer to undergo a cracking reaction. The catalyst mixture includes a regenerated catalyst and a fresh catalyst.

[0014] (3) The reaction products of the first and second reactors and the catalyst to be generated enter the oil-solid separation equipment 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.

[0015] (4) The separated catalyst is stripped and then enters the regenerator for oxygen regeneration. The first part of the regenerated catalyst is returned to the first reactor for reaction cycle use. The second part of the regenerated catalyst enters the catalyst reducer and undergoes a reduction reaction under the action of the reducing medium, releasing energy. The regenerated catalyst after reduction enters the second reactor for reaction cycle use.

[0016] Wherein, the first raw material is low-quality crude oil, and the low-quality crude oil is selected from one or more of intermediate-based crude oil, intermediate-cycloalkyl crude oil, and cycloalkyl-intermediate crude oil;

[0017] The second raw material is self-produced by the unit 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 260-300℃.

[0018] According to the method described in the first aspect, the inferior crude oil satisfies at least one of the following properties: a characteristic factor K value of not less than 11.5; a relative density of not more than 935 kg / m³. 3 The residual carbon content is not greater than 10% by weight; the total content of nickel and vanadium is not greater than 50 mg / kg.

[0019] According to the method of the first aspect, the recalcitrant component includes C4 fraction produced by the device itself and gaseous hydrocarbons rich in C4 fraction produced by other devices, wherein the C4 olefin content in the gaseous hydrocarbons rich in C4 fraction 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 described in the first aspect, the difficult-to-convert components include light distillate oils with a final boiling point of less than 260-300°C produced by the unit itself and optionally one or more of the following fractions: straight-run naphtha, straight-run kerosene, and straight-run diesel produced by other primary processing units; topping oil, residue oil, hydrocracked light naphtha, pentane oil, coking gasoline, Fischer-Tropsch synthetic oil, catalytic cracked light gasoline, hydrotreated gasoline, and hydrotreated diesel produced by other secondary processing units.

[0022] According to the method described in the first aspect, the catalytic cracking reaction temperature in the first reactor is 510-650℃, and the weight hourly space velocity is 1-20 h⁻¹. -1 The catalyst-to-oil weight ratio is (3-50):1, and the catalyst density is 120-290 kg / m³. 3And / or the reaction pressure is 130-450 kPa;

[0023] Preferably, the first raw material is preheated and steam atomized before entering the first reactor. The preheating temperature is 180-350℃ and the water-oil weight ratio is (0.03-0.5):1.

[0024] According to the method of the first aspect, the supplementary catalyst accounts for 0-30% by weight of the total catalyst circulation in the first reactor.

[0025] According to the method described in the first aspect, the second reactor is provided with a main reaction section and one or more feed sections for difficult-to-convert components;

[0026] Preferably, the one or more feed sections for the difficult-to-convert components are each independently located in the middle and upstream of the second reactor;

[0027] Preferably, the catalyst density in the feed section for the difficult-to-convert components is 120-290 kg / m³. 3 ; and / or

[0028] Preferably, the diameter ratio of the feed section for the difficult-to-convert component to the diameter of the main reaction section is (1.2-1.5):1.

[0029] According to the method described in the first aspect, the catalytic cracking reaction temperature in the second reactor is 580-750℃, the reaction time is 0.05-5 seconds, the catalyst-to-oil weight ratio is (1-50):1, and the catalyst density is 20-100 kg / m³. 3 And / or the reaction pressure is 130-450 kPa;

[0030] Preferably, the second raw material is introduced into the second reactor after being atomized by steam, and the water-to-oil weight ratio is (0.03-0.5):1.

[0031] 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.

[0032] According to the method described in the first aspect, the reduction temperature in the catalyst reducer is 550-750℃.

[0033] The restoration time is 2-20 minutes; and / or

[0034] 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.

[0035] According to the method described in the first aspect, the regeneration temperature in the regenerator is 550-750°C, preferably 600-730°C, and more preferably 650-720°C;

[0036] The apparent linear velocity of the gas is 0.5-3 m / s, preferably 0.8-2.5 m / s, and more preferably 1-2 m / s;

[0037] The average residence time of the catalyst is 0.6-3 minutes, preferably 0.8-2.5 minutes, and more preferably 1-2 minutes.

[0038] According to the method of the first aspect, wherein, based on the dry weight of the catalyst, 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.

[0039] Preferably, the catalyst comprises:

[0040] 0-70 parts by weight, preferably 5-60 parts by weight, more preferably 10-50 parts by weight of clay,

[0041] 5-99 parts by weight, preferably 10-80 parts by weight, more preferably 20-70 parts by weight of adhesive,

[0042] 1-60 parts by weight, preferably 5-45 parts by weight, more preferably 10-40 parts by weight of zeolite, and

[0043] 0.001-5 parts by weight, preferably 0.005-2 parts by weight, of a metal oxide.

[0044] And the total weight of the catalyst is 100 parts by weight;

[0045] The adhesive is an inorganic oxide adhesive, preferably silicon dioxide and / or aluminum oxide;

[0046] 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.

[0047] The clay is preferably kaolin and / or hydrous kaolin.

[0048] A second aspect of the present invention provides a catalytic cracking system, comprising:

[0049] The catalytic cracking reaction unit includes:

[0050] The first reactor is equipped 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;

[0051] The second reactor is provided with a pre-lifting section, a feeding 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 feeding section is provided with a difficult-to-convert raw material inlet, a circulating catalyst inlet and an optional outgoing catalyst outlet.

[0052] An oil-liquid separation device is connected to both the outlet of the first oil-liquid mixture from the first reactor and the outlet of the second oil-liquid mixture from the second reactor, such that the first oil-liquid mixture from the first reactor and the second oil-liquid mixture from the second reactor are separated by the oil-liquid separation device into reaction oil gas and catalyst to be generated; and

[0053] 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.

[0054] 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.

[0055] The regenerator includes a 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 catalyst inlet of the regenerator is in fluid communication with the catalyst outlet of the stripping section. One regenerated catalyst outlet is connected to the catalyst inlet of the first reactor for recycling a portion of the regenerated catalyst back to the first reactor.

[0056] 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 reactor, so that the reduced catalyst is circulated back to the second reactor.

[0057] According to the catalytic cracking system described in the second aspect, the first reactor is provided with one or more supplementary catalyst inlets;

[0058] Preferably, the location of the one or more supplementary catalyst inlets is independently located at a height greater than 0% to 90% of the total height of the first reactor, more preferably at a height of 20% to 80% of the total height of the first reactor, and more preferably at a height of 30% to 75% of the total height of the first reactor.

[0059] According to the catalytic cracking system described in the second aspect, the second 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.

[0060] 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.

[0061] Compared with the prior art, the method and system of the present invention have the following advantages:

[0062] 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.

[0063] 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.

[0064] 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 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.

[0065] 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.

[0066] 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.

[0067] The catalytic cracking method of this application can directly and efficiently produce chemical feedstocks such as ethylene and propylene from crude oil, realizing the efficient utilization of crude oil resources, alleviating the situation of excess refined oil, helping refineries to transform, develop and extend from oil refining to chemical feedstock production, reducing production costs and increasing the profitability of refineries. Attached Figure Description

[0068] 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:

[0069] Figure 1 This application provides a schematic diagram of a process for producing low-carbon olefins and aromatics through catalytic cracking of inferior crude oil, according to one embodiment.

[0070] Explanation of reference numerals in the attached figures:

[0071] 100. First reactor; 101. First pre-lifting medium pipeline; 102. First reactor feed pipeline; 103. Catalyst replenishment pipeline; 104. First reactor outlet section; 200. Settler; 201. Lower stripping section of settler; 202. Gas medium pipeline; 203. Preparing inclined tube; 204. Oil-agent separation device; 205. Gas collection chamber; 206. Main oil-gas pipeline; 300. Second reactor; 301. Second pre-lifting medium pipeline; 303. Second reactor first feed pipeline; 304. Second reactor second feed pipeline; 305. Second reactor third feed pipeline; 306. Second reactor External catalyst circulation pipeline; 307, catalyst outlet; 308, second reactor outlet section; 309, second reactor pre-lift section; 310, second reactor main reaction section; 311, second reactor first feed section; 312, second reactor second feed section; 400, regenerator; 401, oxygen-containing gas inlet; 402, gas 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 inclined tube; 504, fresh catalyst pipeline. Detailed Implementation

[0072] 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.

[0073] 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.

[0074] 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.

[0075] 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.

[0076] 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).

[0077] 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.

[0078] 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.

[0079] This invention provides a method for direct catalytic cracking of low-quality crude oil, the method comprising:

[0080] (1) The first raw material and the regenerated catalyst from the regenerator enter the first reactor for catalytic cracking reaction. Optionally, the reaction products are contacted with the introduced supplementary catalyst and the reaction continues.

[0081] (2) The second raw material is introduced from the downstream feed section of the second reactor and comes into contact with the reduced catalyst mixture from the catalyst reducer to undergo a cracking reaction. The catalyst mixture includes a regenerated catalyst and a fresh catalyst.

[0082] (3) The reaction products of the first and second reactors and the catalyst to be generated enter the oil-solid separation equipment 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.

[0083] (4) The separated catalyst is stripped and then enters the regenerator for oxygen regeneration. The first part of the regenerated catalyst is returned to the first reactor for reaction cycle use. The second part of the regenerated catalyst enters the catalyst reducer and undergoes a reduction reaction under the action of the reducing medium, releasing energy. The regenerated catalyst after reduction enters the second reactor for reaction cycle use.

[0084] Wherein, the first raw material is low-quality crude oil, and the low-quality crude oil is selected from one or more of intermediate-based crude oil, intermediate-cycloalkyl crude oil, and cycloalkyl-intermediate crude oil;

[0085] The second raw material is self-produced by the unit 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 260-300℃.

[0086] 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.

[0087] Figure 1 A preferred embodiment of the catalytic cracking method for inferior crude oil of this application is provided, wherein the catalytic cracking reactor includes a first reactor 100 and a second reactor 300. The second 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.

[0088] The pre-lifting medium enters the bottom of the first reactor 100 through the first pre-lifting medium pipeline 101. The lifting medium can be dry gas, water vapor, or a mixture thereof. It mixes with the hot regeneration catalyst from the first regeneration inclined tube 403 and moves upward. The reaction raw materials, such as preheated crude oil and atomized steam, are injected into the lower part of the first reactor 100 through the first reactor feed pipeline 102, where they mix and contact with the high-temperature regeneration catalyst and undergo catalytic cracking reaction. The first reactor is also equipped with a catalyst replenishment pipeline 103 for replenishing the catalyst.

[0089] The hot regenerated catalyst from the second regeneration inclined tube 406 and the fresh catalyst from the fresh catalyst line 504 enter the reducer 500. Under the action of the reducing medium introduced through the reducing medium line 501, the metal oxide on the catalyst undergoes a reduction reaction, releasing energy. The high-temperature regenerated catalyst enters the bottom of the second reactor through the reducing catalyst inclined tube 503 and moves upward under the lifting action of the pre-lifting medium from the second pre-lifting medium line 301. The pre-lifting medium can be steam or refinery dry gas and enters the first feed section of the second reactor.

[0090] The difficult-to-convert feedstock and atomized steam are injected into the lower part of the first feed section 311 of the second reactor via the first feed line 303, where they mix and contact with the existing catalyst in the catalytic cracking reactor. The oil-catalyst mixture moves upward and, optionally, mixes with a portion of the difficult-to-convert feedstock injected via the second feed line 304 and the third feed line 305 of the second reactor, entering the upper part of the second feed section 312. Alternatively, a portion of the difficult-to-convert feedstock enters the lower part of the second feed section 312 via line 305. The oil-catalyst mixture enters the main reaction section 310, where a full cracking reaction occurs. The catalyst-to-oil ratio and activity of the catalyst in the first feed section 311 and the second feed section 312 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. The reaction oil and gas generated by the catalytic cracking reaction in the first and second reactors, along with the catalyst to be generated, flow upward and enter the oil-catalyst separation device 204 (such as a cyclone separator) via the first reactor outlet section 104 and the second reactor outlet section 308, respectively, 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 and enter the subsequent separation system; the separated catalyst enters the lower stripping section 201 of the settling tank 200, and after being stripped by the stripping medium from the stripping medium pipeline 202, it enters the regenerator 400 through the catalyst inclined pipe 203.

[0091] The regenerated catalyst comes into contact with oxygen-containing gas injected through oxygen-containing gas inlet 401 and gas distributor 402 and undergoes a complete combustion reaction, releasing heat. After regeneration, a portion of the catalyst is supplied to the first reactor via the first regeneration inclined tube 403, and the remaining portion is injected into the reducer via the second regeneration inclined tube 406, reduced, and then returned to the second reactor for recycling. The regenerated flue gas, after being separated from entrained catalyst by cyclone separator 404, enters the energy recovery system via regenerated flue gas recovery pipeline 405.

[0092] The catalytic cracking method provided in this application is applicable to crude oil selected from one or more of the following: intermediate-based crude oil, intermediate-cycloalkyl crude oil, or cycloalkyl-intermediate crude oil. Either the first critical component or the second critical group of the intermediate-based crude oil is of intermediate-based nature; the first critical component of the intermediate-cycloalkyl crude oil is of intermediate-based nature and the second critical group is of cycloalkyl nature; the first critical component of the cycloalkyl-intermediate crude oil is of cycloalkyl nature and the second critical group is of intermediate-based nature.

[0093] In one embodiment, the properties of the first raw material, low-quality crude oil, satisfy at least one of the following indicators: a characteristic factor K value of not less than 11.5; and a relative density of not more than 935 kg / m³. 3 The residual carbon content is not greater than 10% by weight; the total content of nickel and vanadium is not greater than 50 mg / kg.

[0094] In one embodiment, the difficult-to-convert component includes C4 fraction produced by the unit itself and gaseous hydrocarbons rich in C4 fraction produced by other units, wherein the C4 olefin content in the gaseous hydrocarbons rich in C4 fraction is greater than 50% by weight.

[0095] Preferably, the difficult-to-convert component is a C4 fraction produced by the device itself.

[0096] The C4 component described in this application refers to low-molecular-weight hydrocarbons that exist 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, 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.

[0097] In one embodiment, the difficult-to-convert components include light distillate oils with a final boiling point of less than 260-300°C produced by the unit itself, and optionally one or more of the following fractions: straight-run naphtha, straight-run kerosene, and straight-run diesel produced by other primary processing units; topping oil, residue oil, hydrocracked light naphtha, pentane oil, coking gasoline, Fischer-Tropsch synthetic oil, catalytic cracked light gasoline, hydrotreated gasoline, and hydrotreated diesel produced by other secondary processing units.

[0098] In this application, the catalytic cracking reaction temperature of the reactor refers to the reactor outlet temperature.

[0099] In one embodiment, the catalytic cracking reaction temperature in the first reactor is 510-650°C, and the weight hourly space velocity is 1-20 h⁻¹. -1 The catalyst-to-oil weight ratio is (3-50):1, and the catalyst density is 120-290 kg / m³. 3 And / or the reaction pressure is 130-450 kPa;

[0100] Preferably, the first raw material is preheated and steam atomized before entering the first reactor. The preheating temperature is 180-350℃ and the water-oil weight ratio is (0.03-0.5):1.

[0101] In one embodiment, a catalyst is added to a first reactor for a cracking reaction, the added catalyst accounting for 0-30% by weight of the total circulating catalyst in the first reactor.

[0102] In some specific embodiments, the supplementary catalyst may account for 0.5 wt%, 1 wt%, 5 wt%, 10 wt%, 15 wt%, 20 wt%, 5 wt%, or 30 wt% of the total catalyst circulation in the first reactor.

[0103] According to this application, a catalyst is added to the first reactor through one or more supplementary catalyst inlets located on the side wall of the first reactor. This catalyst mixes with the reaction products of the feedstock oil and the regenerated catalyst, continuing the catalytic cracking reaction. The supplementary catalyst can be one or more selected from regenerated catalysts, spent catalysts, and semi-regenerated catalysts. The supplemented catalyst can account for 0-30% by weight of the total circulating catalyst volume in the first reactor. The one or more supplementary catalyst inlets are each independently located at a height greater than 0% to 90% of the total height of the first reactor, preferably at 20% to 80% of the total height, and more preferably at 30% to 75%. Supplementing the catalytic cracking catalyst in a fast fluidized bed allows for a wider adjustment of the catalyst-to-oil ratio, providing more active sites for the cracking reaction. Simultaneously, it enhances the flexibility of reaction temperature control, effectively regulating the temperature and catalyst activity gradient within the fast fluidized bed. Furthermore, supplementing the catalytic cracking catalyst in a fast fluidized bed helps maintain the uniformity of catalyst density in the reactor, effectively regulating the catalyst density distribution, ensuring the cracking reaction proceeds fully and effectively, and improving the selectivity of the target product.

[0104] In one embodiment, the second reactor is provided with a main reaction section and one or more feed sections for difficult-to-convert components;

[0105] Preferably, the one or more feed sections for the difficult-to-convert components are each independently located in the middle and upstream of the second reactor;

[0106] Preferably, the catalyst density in the feed section for the difficult-to-convert components is 120-290 kg / m³. 3 ; and / or

[0107] Preferably, the diameter ratio of the feed section for the difficult-to-convert component to the diameter of the main reaction section is (1.2-1.5):1.

[0108] In one embodiment, one or more of the difficult-to-convert components may be fed at at least one or more identical locations in the feed section of the second reactor, or they may be fed at different locations.

[0109] This invention does not pursue high single-pass conversion rates in the crude oil catalytic cracking process. Instead, it utilizes a recycling method for the difficult-to-convert light distillate oil, achieving high overall conversion rates and high selectivity for target products by setting up specific reaction zones. Based on the reactivity of the difficult-to-convert components, they are introduced into the reactor in a specific feed section of the second reactor. The higher catalyst density and activity in the feed section are beneficial for improving the reaction conversion rate and catalytic selectivity of the difficult-to-convert components.

[0110] In one embodiment, the catalytic cracking reaction temperature in the second reactor is 580-750℃, the reaction time is 0.05-5 seconds, the catalyst-to-oil weight ratio is (1-50):1, and the catalyst density is 20-100 kg / m³. 3 And / or the reaction pressure is 130-450 kPa;

[0111] Preferably, the second raw material is introduced into the second reactor after being atomized by steam, and the water-to-oil weight ratio is (0.03-0.5):1.

[0112] In one embodiment, the weight ratio of fresh catalyst to regenerated catalyst in the catalyst reducer is (0.005-0.3):1.

[0113] In one embodiment, the reduction temperature in the catalyst reducer is 550-750°C, and the reduction time is 2-20 minutes; and / or

[0114] 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.

[0115] In one embodiment, the coke-containing spent catalyst separated by the oil-separation device is stripped and then enters the regenerator, where it comes into contact with oxygen-containing gas injected into the regenerator and undergoes a combustion reaction.

[0116] Inside the regenerator, the regeneration temperature is 550-750℃, preferably 600-730℃, and more preferably 650-720℃;

[0117] The apparent linear velocity of the gas is 0.5-3 m / s, preferably 0.8-2.5 m / s, and more preferably 1-2 m / s;

[0118] The average residence time of the catalyst is 0.6-3 minutes, preferably 0.8-2.5 minutes, and more preferably 1-2 minutes.

[0119] In one embodiment, the catalyst comprises 0.01-5 wt%, preferably 0.005-2 wt%, of a metal oxide, based on a dry weight of the catalyst, wherein the metal oxide is selected from one or more of the following: tin, cobalt, iron, molybdenum, manganese, copper, barium, and chromium.

[0120] Preferably, the catalyst comprises:

[0121] 0-70 parts by weight, preferably 5-60 parts by weight, more preferably 10-50 parts by weight of clay,

[0122] 5-99 parts by weight, preferably 10-80 parts by weight, more preferably 20-70 parts by weight of adhesive,

[0123] 1-60 parts by weight, preferably 5-45 parts by weight, more preferably 10-40 parts by weight of zeolite, and

[0124] 0.001-5 parts by weight, preferably 0.005-2 parts by weight, of a metal oxide.

[0125] And the total weight of the catalyst is 100 parts by weight;

[0126] The adhesive is an inorganic oxide adhesive, preferably silicon dioxide and / or aluminum oxide;

[0127] 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.

[0128] The clay is preferably kaolin and / or hydrous kaolin.

[0129] In the catalyst used in this invention, clay is used as the catalyst matrix (i.e., support), and inorganic oxides are used as binders.

[0130] In this application, 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.

[0131] 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.

[0132] The catalyst of this invention contains a metal with a variable valence state. It stores and releases energy through the gain or loss of electrons between the metal and the metal oxide or the shift of shared electron pairs, thereby providing heat for the catalytic cracking reaction of difficult-to-convert components and solving the problem of high reaction heat demand of difficult-to-convert components.

[0133] 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.

[0134] 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 fractions.

[0135] 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.

[0136] The present invention also provides a catalytic cracking system, comprising:

[0137] The catalytic cracking reaction unit includes:

[0138] The first reactor is equipped 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;

[0139] The second reactor is provided with a pre-lifting section, a feeding 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 feeding section is provided with a difficult-to-convert raw material inlet, a circulating catalyst inlet and an optional outgoing catalyst outlet.

[0140] An oil-liquid separation device is connected to both the outlet of the first oil-liquid mixture from the first reactor and the outlet of the second oil-liquid mixture from the second reactor, such that the first oil-liquid mixture from the first reactor and the second oil-liquid mixture from the second reactor are separated by the oil-liquid separation device into reaction oil gas and catalyst to be generated; and

[0141] 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.

[0142] 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.

[0143] The regenerator includes a 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 catalyst inlet of the regenerator is in fluid communication with the catalyst outlet of the stripping section. One regenerated catalyst outlet is connected to the catalyst inlet of the first reactor for recycling a portion of the regenerated catalyst back to the first reactor.

[0144] 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 reactor, so that the reduced catalyst is circulated back to the second reactor.

[0145] In one embodiment, the first reactor is provided with one or more supplemental catalyst inlets;

[0146] Preferably, the location of the one or more supplementary catalyst inlets is independently located at a height greater than 0% to 90% of the total height of the first reactor, more preferably at a height of 20% to 80% of the total height of the first reactor, and more preferably at a height of 30% to 75% of the total height of the first reactor.

[0147] The total height of the first reactor is the total height from the feed oil inlet to the outlet of the first oil-agent mixture. The total height of the first reactor is... Figure 1 The middle label is H1.

[0148] In one embodiment, a gas distributor is provided at the bottom of the regenerator, so that oxygen-containing gas injected through the oxygen-containing gas inlet of the regenerator enters the regenerator through the gas distributor. According to this application, the 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.

[0149] In one embodiment, the second 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.

[0150] 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.

[0151] In the second feed section, the catalyst 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.

[0152] The catalytic cracking system of this application includes a first reactor and a second reactor, an oil-to-product separation device, a reaction product separation device, a catalyst regenerator, and a reducer. The first reactor and the second reactor are connected to the oil-to-product separation device. A settling tank with fluid communication is provided above the first reactor, and a stripping section with fluid communication is provided below the first reactor.

[0153] The first reactor is equipped with a catalyst inlet, a supplementary catalyst inlet, a feed oil inlet, and an oil-agent mixture outlet. The stripping section is equipped with a catalyst outlet. The settler is equipped with a reaction product outlet and an optional oil-agent inlet. The oil-agent separation device is equipped with an oil-agent inlet, a catalyst outlet, and a reaction product outlet. The second reactor, from bottom to top, consists of a pre-lifting section, a first feed section, an optional second feed section, a main reaction section, and an outlet section. The pre-lifting section is equipped with a regenerated catalyst inlet and a pre-lifting medium inlet at the bottom. The first feed section is equipped with a catalyst inlet, a difficult-to-convert feed inlet, a circulating catalyst inlet, and an oil-agent mixture outlet. The second feed section is equipped with a difficult-to-convert feed inlet, a circulating catalyst outlet, and an optional outgoing catalyst outlet. An external catalyst circulation pipeline connecting the first feed section and the second feed section is provided.

[0154] The catalyst inlet of the catalyst reducer and the second reactor are in fluid communication with the catalyst outlet of the regenerator. The first reactor and the second reactor are arranged in parallel and connected by an oil-agent separation device. The reaction product outlet of the settling tank is in fluid communication with the oil inlet of the oil-agent separation device. The oil outlet of the first reactor is in fluid communication with either the oil inlet of the settling tank or the oil inlet of the oil-agent separation device. The reaction product outlet of the oil-agent separation device is in fluid communication with the reaction product inlet of the reaction product separation device. The catalyst outlet of the stripping section is in fluid communication with the catalyst inlet of the regenerator.

[0155] The catalyst reducer is provided with a regenerated catalyst inlet, a fresh catalyst inlet, a catalyst outlet, and a reduction medium inlet; the catalyst reducer and the second reactor can be arranged side by side or coaxially.

[0156] 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.

[0157] The following embodiments will further illustrate this application, but do not limit this application.

[0158] The feedstock used in the following examples and comparative examples is imported crude oil, which is intermediate-base crude oil and is sourced from a branch of Sinopec. Its properties are shown in Table 1. The catalyst used in the examples is DMMC-1 catalyst containing CuO. The amount of CuO used is 1.0 wt% based on the total weight of the catalyst.

[0159] Example 1

[0160] 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:

[0161] The first reactor has a total height of 7 meters and an inner diameter of 0.3 meters. The second reactor has a height of 5 meters and an inner diameter of 0.2 meters. There are two feeding sections at the bottom, each with a height of 0.2 meters and an inner diameter of 0.3 meters. The first feeding section has one feeding inlet and the second feeding section has one feeding inlet.

[0162] The hot regenerated catalyst in the first regeneration inclined tube 403 enters the lower part of the first 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 reactor through the feed pipeline at 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. The post-reaction stream enters the subsequent oil-to-catalyst separation unit 204 and product separation equipment. A hot regenerated catalyst is added to the first reactor at a height of 50% of the first reactor, and the amount of the added regenerated catalyst accounts for 10% by weight of the reactor catalyst circulation volume.

[0163] 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 reactor through the reduction catalyst inclined tube 503. Under the action of the pre-lifting medium injected through the second pre-lifting medium line 301, it moves upward. The C4 fraction and light distillate oil with a distillation range of less than 300°C from the fractionation unit enter the bottom of the first feed section through the first feed line 303 of the second reactor. The water-oil weight ratio is 0.25:1. It comes into contact with the existing catalyst in the reactor and moves upward, entering the main reaction section 310 and undergoing a catalytic cracking reaction. The reaction oil-agent mixture moves upward, and the post-reaction stream enters the subsequent oil-agent separation equipment and product separation equipment.

[0164] The catalyst containing coke obtained from the first and second reactors, along with the reaction oil and gas, enter the oil-solid 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 containing coke enters the lower part of the settling tank 200 and then enters the regenerator 400 through the waiting inclined pipe 203.

[0165] The catalyst containing coke enters the regenerator, where it comes into contact with air and undergoes a combustion reaction. Part of the regenerated catalyst is returned to the first reactor for use in the reaction cycle, while another part of the regenerated catalyst enters the reducer. The regenerated catalyst after reduction is returned to the second reactor for use in the reaction cycle. The regenerated flue gas enters the energy recovery system through the regenerated flue gas recovery pipeline 405.

[0166] Operating conditions and product distribution are listed in Tables 2 and 3. As can be seen from Table 3, the yields of low-carbon olefins and light aromatics in this embodiment reached 47.84% by weight, and correspondingly, the total selectivity of low-carbon olefins and light aromatics reached 58.12% by weight.

[0167] Example 2

[0168] 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:

[0169] The first reactor has a total height of 7 meters and an inner diameter of 0.3 meters. The second reactor has a height of 5 meters and an inner diameter of 0.2 meters. There are two feeding sections at the bottom, each with a height of 0.2 meters and an inner diameter of 0.3 meters. The first feeding section has one feeding inlet, and the second feeding section has two feeding inlets.

[0170] The hot regenerated catalyst in the first regeneration inclined tube 403 enters the lower part of the first 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 reactor through the feed pipeline at 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. The post-reaction stream enters the subsequent oil-to-catalyst separation equipment and product separation equipment. A hot regenerated catalyst is added to the first reactor at a height of 50% of the first reactor, and the amount of the added regenerated catalyst accounts for 10% by weight of the reactor's catalyst circulation volume.

[0171] 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 reactor through the reduction catalyst inclined tube 503. Under the action of the pre-lifting medium injected through the second pre-lifting medium line 301, it moves upward. The C4 fraction enters the bottom of the first feed section through the first feed line 303 of the second reactor, contacts the existing catalyst in the reactor, and moves upward. The light distillate oil with a water-to-oil weight ratio of 0.25:1 and a distillation range of less than 300℃ enters the bottom of the second feed section through the second feed line 304 of the second reactor, contacts the existing catalyst in the reactor, and moves upward. It enters the main reaction section 310 and undergoes a catalytic cracking reaction. The reaction oil-agent mixture moves upward, and the post-reaction stream enters the subsequent oil-agent separation equipment and product separation equipment.

[0172] The catalyst containing coke obtained from the first and second reactors, along with the reaction oil and gas, enter the oil-solid 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 containing coke enters the lower part of the settling tank 200 and then enters the regenerator 400 through the waiting inclined pipe 203.

[0173] The catalyst containing coke enters the regenerator, where it comes into contact with air and undergoes a combustion reaction. Part of the regenerated catalyst is returned to the first reactor for use in the reaction cycle, while another part of the regenerated catalyst enters the reducer. The regenerated catalyst after reduction is returned to the second reactor for use in the reaction cycle. The regenerated flue gas enters the energy recovery system through the regenerated flue gas recovery pipeline 405.

[0174] Operating conditions and product distribution are listed in Tables 2 and 3. As can be seen from Table 3, the yields of low-carbon olefins and light aromatics in this embodiment reached 49.70% by weight, and correspondingly, the total selectivity of low-carbon olefins and light aromatics reached 58.20% by weight.

[0175] Comparative Example 1

[0176] The catalyst used in the comparative example was a commercial catalytic cracking catalyst purchased from the Catalyst Division of China Petroleum & Chemical Corporation (Sinopec), brand name DMMC-1. Using the feedstock and DMMC-1 catalyst shown in Table 1, experiments were conducted on a medium-sized unit. The first reactor was a conventional riser reactor connected in series with a fluidized bed reactor, and the second reactor was a riser reactor. Preheated crude 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 the subsequent oil-to-catalyst separation unit and product separation equipment. The separated C4 fraction and light distillate oil with a distillation range less than 300°C entered the second reactor to contact the catalytic cracking catalyst for catalytic cracking. The post-reaction stream entered the oil-to-catalyst separation unit of the first reactor. The separated spent catalyst entered the lower part of the regenerator, where it contacted the air distributed into the regenerator by the main air distributor to undergo a coking reaction. The regenerated catalyst was returned to the reactor for recycling. Operating conditions and product distribution are listed in Tables 2 and 3.

[0177] As can be seen from the results in Table 3, the yields of low-carbon olefins and light aromatics in this comparative example reached 35.28% by weight, and the total selectivity of low-carbon olefins and light aromatics was 45.40% by weight.

[0178] As can be seen from the results of the above examples and comparative examples, when the catalytic cracking method and system of this application are used for crude oil catalytic cracking reaction, the crude oil atom utilization rate is high and the yield of low-carbon olefins and aromatics is significantly improved.

[0179] 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.

[0180] 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.

[0181] Properties of the crude oil used (Table 1)

[0182] Crude oil classification intermediate base crude oil Characteristic factor K value 11.9 <![CDATA[Density (20 °C) / (kg / m 3 )]]> 880.2 Carbon content / weight % 85.91 Hydrogen content / weight % 12.62 Sulfur content / weight % 0.865 Nitrogen content / weight % 0.23 Residual carbon value / % by weight 4.09 Metal content (mg / kg) Fe 3.3 Ni 14 V 12 Na 0.1 Ca 0.3

[0183] Table 2 Reaction conditions of Examples 1, 2 and Comparative Example 1

[0184]

[0185]

[0186] Table 3 Comparison of reaction results of Examples 1 and 2 and Comparative Example 1

[0187] Example 1 Example 2 Comparative Example 1 Product distribution, weight % gas 52.05 55.12 40.36 ethylene 9.06 9.88 3.97 Among them, propylene 23.97 24.81 16.51 Butene 4.98 5.43 10.59 liquid 38.34 34.98 49.87 Among them, light aromatics 9.83 9.57 7.87 total 100.00 100.00 100.00 Conversion rate, % 82.31 85.39 77.71 Yields of low-carbon olefins and light aromatics, % 47.84 49.70 35.28 Low carbon olefins and light aromatics selectivity, % 58.12 58.20 45.40

Claims

1. A method for direct catalytic cracking of low-quality crude oil, characterized in that, The method includes: (1) The first raw material and the regenerated catalyst from the regenerator enter the first 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 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 reactor and the second reactor and the catalyst to be generated enter the oil-solid separation equipment 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. (4) The separated catalyst is stripped and then enters the regenerator for oxygen regeneration. The first part of the regenerated catalyst is returned to the first reactor for reaction cycle. The second part of the regenerated catalyst enters the catalyst reducer and undergoes a reduction reaction under the action of the reducing medium, releasing energy. The regenerated catalyst after reduction enters the second reactor for reaction cycle. Wherein, the first raw material is low-quality crude oil, and the low-quality crude oil is selected from one or more of intermediate-based crude oil, intermediate-cycloalkyl crude oil, and cycloalkyl-intermediate crude oil; The second feedstock is self-produced by the unit 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 260-300℃; Based on the dry weight of the catalyst, the catalyst comprises 0.001-5 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.

2. The method according to claim 1, characterized in that, The inferior crude oil meets at least one of the following criteria: a characteristic factor K value of not less than 11.5; a relative density of not more than 935 kg / m³. 3 The residual carbon content is not greater than 10% by weight; the total content of nickel and vanadium is not greater than 50 mg / kg.

3. The method according to claim 1, characterized in that, The difficult-to-convert components include C4 fractions produced by the unit itself and 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 difficult-to-convert components include light distillate oils with a final boiling point of less than 260-300℃ produced by the unit and one or more of the following fractions: straight-run naphtha, straight-run kerosene, and straight-run diesel produced by other primary processing units; topping oil, residue oil, hydrocracked light naphtha, pentane oil, coking gasoline, Fischer-Tropsch synthetic oil, catalytic cracked light gasoline, hydrotreated gasoline, and hydrotreated diesel produced by other secondary processing units.

6. The method according to claim 1, characterized in that, The catalytic cracking reaction temperature in the first reactor is 510-650℃, and the weight hourly space velocity is 1-20 h⁻¹. -1 The catalyst-to-oil weight ratio is (3-50):1, and the catalyst density is 120-290 kg / m³. 3 And / or the reaction pressure is 130-450 kPa.

7. The method according to claim 1, characterized in that, The first raw material is preheated and steam atomized before entering the first reactor. The preheating temperature is 180-350℃, and the water-oil weight ratio is (0.03-0.5):

1.

8. The method according to claim 1, characterized in that, The supplementary catalyst accounts for 0-30% of the total catalyst circulation volume in the first reactor by weight.

9. The method according to claim 1, characterized in that, The second 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 the one or more recalcitrant components are each independently located in the middle and upstream of the second reactor; The catalyst density in the feed section for the recalcitrant components is 120-290 kg / m³. 3 ; and / or The diameter ratio of the feed section for the difficult-to-convert components to the diameter of the main reaction section is (1.2-1.5):

1.

11. The method according to claim 1, characterized in that, In the second reactor, the catalytic cracking reaction temperature is 580-750℃, the reaction time is 0.05-5 seconds, the catalyst-to-oil weight ratio is (1-50):1, and the catalyst density is 20-100 kg / m³. 3 And / or the reaction pressure is 130-450 kPa.

12. The method according to claim 11, characterized in that, The second raw material is introduced into the second 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 550-750℃. 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 regeneration temperature inside the regenerator is 550-750℃; The apparent linear velocity of the gas is 0.5-3 m / s; The average residence time of the catalyst is 0.6-3 minutes.

17. The method according to claim 16, characterized in that, The regeneration temperature inside the regenerator is 600-730℃; The apparent linear velocity of the gas is 0.8-2.5 m / s; The average residence time of the catalyst is 0.8-2.5 minutes.

18. The method according to claim 17, characterized in that, The regeneration temperature inside the regenerator is 650-720℃; The apparent linear velocity of the gas is 1-2 m / s; The average residence time of the catalyst is 1-2 minutes.

19. The method according to claim 1, characterized in that, Based on the dry weight of the catalyst, the catalyst comprises 0.005-2 wt% of metal oxide.

20. The method according to claim 1, characterized in that, The catalyst includes: 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 oxides, 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.

21. The method according to claim 20, 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, 0.005-2 parts by weight of metal oxide.

22. The method according to claim 21, 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.

23. The method according to claim 20, wherein the adhesive is silicon dioxide and / or aluminum oxide; The clay is kaolin and / or hydrous kaolin.

24. The method according to claim 20, wherein the mesoporous zeolite accounts for 5-100% of the total weight of the zeolite.

25. The method according to claim 24, characterized in that, The mesoporous zeolite accounts for 50-90% of the total weight of the zeolite.

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

27. A catalytic cracking system for carrying out the method of any one of claims 1-26, comprising: The catalytic cracking reaction unit includes: The first reactor is equipped 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 reactor is provided with a pre-lifting section, a feeding 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 feeding 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 reactor and the outlet of the second oil-liquid mixture from the second reactor, such that the first oil-liquid mixture from the first reactor and the second oil-liquid mixture from the second reactor are separated by the oil-liquid separation device into reaction oil gas and catalyst to be generated; 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. 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 regenerator includes a 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 catalyst inlet of the regenerator is in fluid communication with the catalyst outlet of the stripping section. One regenerated catalyst outlet is connected to the catalyst inlet of the first reactor for recycling a portion of the regenerated catalyst back to the first reactor. 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 reactor, so that the reduced catalyst is circulated back to the second reactor.

28. The system according to claim 27, characterized in that, The first reactor is provided with one or more supplemental catalyst inlets.

29. The system according to claim 28, characterized in that, The location of each of the one or more supplementary catalyst inlets is independently located at a height greater than 0% to 90% of the total height of the first reactor.

30. The system according to claim 29, characterized in that, The location of each of the one or more supplementary catalyst inlets is independently located at 20% to 80% of the total height of the first reactor.

31. The system according to claim 30, characterized in that, The location of each of the one or more supplementary catalyst inlets is independently located at 30% to 75% of the total height of the first reactor.

32. The system according to claim 27, characterized in that, The second 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.

33. The system according to claim 32, 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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