Process and system for catalytic cracking of inferior crude oil to produce low carbon olefins and aromatics

Abstract

The application relates to a method and system for producing low-carbon olefins and aromatic hydrocarbons through catalytic cracking of poor crude oil, which comprises the following steps: crude oil is separated into a light crude oil fraction and a heavy crude oil fraction through distillation; the heavy crude oil fraction is subjected to a catalytic cracking reaction in a first reactor; the light crude oil fraction is subjected to a catalytic cracking reaction in a second reactor; after the reaction products and spent catalyst are separated through gas-solid separation, the spent catalyst is regenerated through stripping and coking and then 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 subjected to a further catalytic cracking reaction in the second reactor to obtain ethylene and propylene. When the catalytic cracking method and system are used for the catalytic cracking reaction of crude oil, ethylene, propylene and other chemical raw materials can be produced with high selectivity, and efficient utilization of crude oil resources is realized.

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 and aromatics from 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 crude oil distillation for fraction separation before catalytic cracking. 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 performance differences of the different fractions, which to some extent helps improve the conversion rate of crude oil molecular cracking. However, due to the significant differences in molecular size and structure between light and heavy crude oil fractions, when the reaction system uses a single catalyst, it is difficult for the catalyst properties to simultaneously meet the catalytic cracking performance requirements of both light and heavy crude oil fractions, resulting in relatively low selectivity for the target product. Summary of the Invention

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

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

[0012] (1) The crude oil is distilled and cut into light crude oil fraction and heavy crude oil fraction, wherein the cutting point of the light crude oil fraction and the heavy crude oil fraction is in the range of 280-360℃.

[0013] (2) The crude oil heavy fraction and the first 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 continue to react.

[0014] (3) The second regenerated catalyst and the fresh catalyst are mixed in the catalyst mixing zone at the bottom of the second reactor to obtain a catalyst mixture. The catalyst mixture flows downstream of the second reactor under the action of the fluidizing medium and contacts the light fraction of crude oil and the difficult-to-convert components fed into the second reactor in sequence to undergo a cracking reaction.

[0015] (4) The mixture of the reaction products from the first reactor and the second reactor and the catalyst to be generated enters 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.

[0016] (5) The separated catalyst containing coke is stripped and then enters the regenerator for oxygen regeneration. The regenerated catalyst is returned to the first and second reactors for use in the reaction cycle.

[0017] The crude oil is selected from one or more of intermediate-based crude oil, intermediate-cycloalkyl crude oil, and cycloalkyl-intermediate crude oil, and the difficult-to-convert components are C4 components and / or light distillate oils with a final boiling point of less than 280-360℃.

[0018] According to the method described in the first aspect, the properties of the crude oil satisfy at least one of the following indicators: a characteristic factor K value not greater than 12.2, and a density of 800-935 kg / m³. 3 The residual carbon content is 2-10% by weight, and the total nickel and vanadium content is 5-50 ppm.

[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 feedstock is a gaseous hydrocarbon rich in 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 of the first reactor include: a reaction temperature of 510-650°C and a weight hourly space velocity of 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;

[0025] Preferably, the crude oil heavy fraction is atomized by steam and then enters the first reactor, with a water-to-oil weight ratio of (0.03-0.8):1.

[0026] According to the method described in the first aspect, the reaction conditions in the second reactor include: a reaction temperature of 580-750℃, a reaction time of 0.05-5 seconds, a catalyst-to-oil weight ratio of (1-50):1, and a catalyst density of 20-100 kg / m³. 3 And / or the reaction pressure is 130-450 kPa;

[0027] Preferably, the light fraction of crude oil is atomized by steam and then enters the second reactor, with a water-to-oil weight ratio of (0.03-0.5):1.

[0028] According to the method described in the first aspect, in the second reactor, the weight ratio of fresh catalyst to regenerated catalyst is 0.01-0.3:1; and / or

[0029] The reaction conditions for the difficult-to-convert component are: a reaction temperature of 560-720℃ and / or a reaction time of 0.1-3 seconds.

[0030] According to the method of the first aspect, wherein the regeneration conditions of the regenerator include:

[0031] Temperature 550-700℃, preferably 600-650℃;

[0032] The apparent linear velocity of the gas is 0.2-1.2 m / s, preferably 0.4-0.8 m / s; and / or

[0033] The average residence time of the catalyst is 1-10 minutes, preferably 2-6 minutes.

[0034] According to the method described in the first aspect, the CO concentration in the regenerated flue gas of the regenerator is 0.5-6% by volume.

[0035] A second aspect of the present invention provides a catalytic cracking system, comprising:

[0036] The crude oil distillation unit is used to separate crude oil into light and heavy fractions.

[0037] The catalytic cracking reaction unit includes:

[0038] The first reactor is provided with a first pre-lifting medium inlet, a first regeneration catalyst inlet, a supplementary catalyst inlet, a crude oil heavy fraction inlet, and a first oil-agent mixture outlet;

[0039] The second reactor is provided with a catalyst mixing zone, a crude oil light fraction inlet, a difficult-to-convert component inlet, and a second oil-agent mixture outlet in sequence. The catalyst mixing zone is provided with a second pre-lifting medium inlet, a second regenerated catalyst inlet, and a fresh catalyst inlet, which are used to mix the regenerated catalyst and fresh catalyst recycled back to the second reactor.

[0040] An oil-liquid separation device is used to separate a first oil-liquid mixture from a first reactor and a second oil-liquid mixture from a second reactor into reaction oil gas and a catalyst to be generated; and

[0041] 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.

[0042] Preferably, the first reactor and the second reactor are arranged side by side;

[0043] A reaction product separation unit, connected to an oil separation device, is used to separate the reaction oil and gas separated by the oil separation device; and

[0044] 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 catalyst outlet. The catalyst inlet of the regenerator is in fluid communication with the catalyst outlet of the stripping section. One catalyst outlet is connected to the catalyst inlet of the first reactor for recycling a portion of the catalyst back to the first reactor. Another catalyst outlet is connected to the catalyst inlet of the second reactor for recycling a portion of the catalyst back to the first reactor.

[0045] According to the system described in the second aspect, the first reactor is provided with one or more supplementary catalyst inlets, each of the one or more supplementary catalyst inlets being located independently at a height greater than 0% to 90% of the total height of the first reactor, 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.

[0046] Compared with the prior art, the method and system of the present invention have the following advantages:

[0047] 1) The relatively difficult light fractions of crude oil are subjected to catalytic cracking in a separate reactor. At the same time, fresh catalyst is incorporated into the regenerated catalyst to adjust the acid properties of the regenerated catalyst, providing a suitable catalyst for the light fractions of crude oil, thereby improving the conversion rate of the cracking reaction and the selectivity of low-carbon olefins.

[0048] 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.

[0049] 3) The regenerator uses an incomplete regeneration method, which allows the regenerated catalyst to carry a small amount of carbon. This carbon adheres to the heavy metals deposited during the reaction, which can mitigate the problem of decreased reaction selectivity caused by the destruction of the molecular sieve framework by heavy metals in crude oil.

[0050] 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

[0051] 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:

[0052] Figure 1 A schematic diagram of a process for producing low-carbon olefins and aromatics by catalytic cracking of crude oil according to one embodiment of this application.

[0053] Explanation of reference numerals in the attached figures:

[0054] 100. First reactor; 101. First pre-lifting medium inlet; 102. Crude oil heavy fraction inlet; 103. Regeneration inclined tube; 104. Oil-catalyst mixture outlet; 105. Supplementary catalyst inlet; 200. Settler; 201. Stripping section; 202. Stripping medium inlet; 203. Regenerated inclined tube; 204. Oil-catalyst separation unit; 205. Gas collection chamber; 206. Main oil and gas pipeline; 300. Second reactor; 301. Second pre-lifting medium inlet; 302. Fresh catalyst inlet; 303. Second regenerated catalyst inlet; 304. Crude oil light fraction inlet; 305. Difficult-to-convert feedstock inlet; 306. Catalyst mixing zone; 400. Regenerator; 401. Oxygen-containing gas inlet; 402. Gas distributor; 404. Cyclone separator; 405. Regenerated flue gas pipeline; 600. Crude oil distillation unit; 601. Light fraction outlet; 602. Heavy fraction outlet. Detailed Implementation

[0055] 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.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] 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).

[0060] 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.

[0061] 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.

[0062] This invention provides a method for producing low-carbon olefins and aromatics by catalytic cracking of inferior crude oil, comprising:

[0063] (1) The crude oil is distilled and cut into light crude oil fraction and heavy crude oil fraction, wherein the cutting point of the light crude oil fraction and the heavy crude oil fraction is in the range of 280-360℃.

[0064] (2) The crude oil heavy fraction and the first 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 continue to react.

[0065] (3) The second regenerated catalyst and the fresh catalyst are mixed in the catalyst mixing zone at the bottom of the second reactor to obtain a catalyst mixture. The catalyst mixture flows downstream of the second reactor under the action of the fluidizing medium and contacts the light fraction of crude oil and the difficult-to-convert components fed into the second reactor in sequence to undergo a cracking reaction.

[0066] (4) The mixture of the reaction products from the first reactor and the second reactor and the catalyst to be generated enters 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.

[0067] (5) The separated catalyst containing coke is stripped and then enters the regenerator for oxygen regeneration. The regenerated catalyst is returned to the first and second reactors for use in the reaction cycle.

[0068] The crude oil is selected from one or more of intermediate-based crude oil, intermediate-cycloalkyl crude oil, and cycloalkyl-intermediate crude oil, and the difficult-to-convert components are C4 components and / or light distillate oils with a final boiling point of less than 280-360℃.

[0069] 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.

[0070] Figure 1 A preferred embodiment of the crude oil catalytic cracking method of this application is provided, wherein the crude oil distillation unit 600 is provided with a light fraction outlet 601 and a heavy fraction outlet 602; the catalytic cracking reactor includes a first reactor 100 and a second reactor 300, and a regenerator 400. The first reactor 100, from bottom to top, is provided with a first pre-lifting medium inlet 101, a first regenerated catalyst inlet connected to a regeneration inclined tube 103, a crude oil heavy fraction inlet 102, a supplementary catalyst inlet, and an oil-catalyst mixture outlet 104. The second reactor 300 is provided with a bottom catalyst mixing zone 306, a lower crude oil light fraction inlet 304, and a mid-to-upper difficult-to-convert feedstock inlet 305. The catalyst mixing zone 306 is provided with a second pre-lifting medium inlet 301, a fresh catalyst inlet 302, and a second regenerated catalyst inlet 303.

[0071] The pre-lifting medium enters the bottom of the first reactor 100 through the first pre-lifting medium inlet 101. The lifting medium can be dry gas, water vapor, or a mixture thereof. It mixes with the hot regeneration catalyst from the regeneration inclined tube 103 and moves upward. The reaction feedstock, such as preheated crude oil heavy fraction, is mixed with atomized steam through pipeline 602 and injected into the lower part of the first reactor 100 through the feed crude oil heavy fraction inlet 102. It mixes and contacts with the high-temperature regeneration catalyst and undergoes catalytic cracking reaction. The reacting oil mixes and moves upward, and continues to move upward by mixing with the supplementary catalyst introduced through the supplementary catalyst inlet 105.

[0072] The hot regenerated catalyst from the regeneration inclined tube 303 and the fresh catalyst from the fresh catalyst inlet 302 enter the catalyst mixing zone 306 at the bottom of the second reactor 300. Under the lifting action of the pre-lifting medium from the second pre-lifting medium inlet 301, they move upward and mix thoroughly. At the outlet of the catalyst mixing zone 306, the mixed catalyst contacts the mixture of crude oil light fraction 601 introduced through the crude oil light fraction inlet 304 and atomized steam and undergoes a catalytic cracking reaction. The resulting oil-catalyst mixture moves upward and contacts the difficult-to-convert components introduced through the difficult-to-convert feedstock inlet 305 and undergoes a catalytic cracking reaction.

[0073] The reaction oil and gas from the first and second reactors, along with the catalyst to be generated, flow upwards through the oil-catalyst mixture outlet 104 and enter the oil-catalyst 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-gas pipe 206 to 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 inlet 202, it enters the regenerator 400 through the catalyst inclined pipe 203.

[0074] The regenerated catalyst comes into contact with oxygen-containing gas injected through oxygen-containing gas inlet 401 and gas distributor 402 and undergoes an incomplete combustion reaction, releasing heat. After regeneration, part of the regenerated catalyst is supplied to the first reactor via pipeline 103, and part of the regenerated catalyst is supplied to the second reactor via pipeline 303 for recycling. The regenerated flue gas is separated from the entrained catalyst by cyclone separator 404 and then enters the energy recovery system via regenerated flue gas pipeline 405.

[0075] 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.

[0076] In one embodiment, the crude oil has properties that satisfy at least one of the following indicators: a characteristic factor K value not greater than 12.2, and a density of 800-935 kg / m³. 3 The residual carbon content is 2-10% by weight, and the total nickel and vanadium content is 5-50 ppm.

[0077] 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.

[0078] 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.

[0079] In one embodiment, the light distillate oil with a final boiling point of less than 280-360°C includes light distillate oil with a final boiling point of less than 280-360°C produced by the apparatus of the present invention. It may also include one or more mixtures of primary processed straight-run naphtha, straight-run kerosene, and straight-run diesel; and one or more mixtures of secondary processed topping oil, residue oil, hydrocracked light naphtha, pentane oil, coking gasoline, Fischer-Tropsch synthetic oil, catalytic cracked light gasoline, hydrotreated gasoline, and hydrotreated diesel.

[0080] 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.

[0081] Preferably, the difficult-to-convert feedstock is a gaseous hydrocarbon rich in C4 fraction produced by the device itself.

[0082] 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:

[0083] Other primary processing units produce straight-run naphtha, straight-run kerosene, and straight-run diesel oil;

[0084] 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.

[0085] In one embodiment, the reaction conditions of the first reactor include: a reaction temperature of 510-650°C and a weight hourly space velocity of 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, and the catalyst mass flow rate Gs is 15-150 kg / (m). 2 ·Second);

[0086] Preferably, the crude oil heavy fraction is atomized by steam and then enters the first reactor, with a water-to-oil weight ratio of (0.03-0.8):1.

[0087] In one embodiment, the reaction conditions of the second reactor include: a reaction temperature of 580-750°C, a reaction time of 0.05-5 seconds, a catalyst-to-oil weight ratio of (1-50):1, and a catalyst density of 20-100 kg / m³. 3 And / or the reaction pressure is 130-450 kPa, and the catalyst mass flow rate Gs is 180-500 kg / (m). 2 ·Second);

[0088] Preferably, the light fraction of crude oil is atomized by steam and then enters the second reactor, with a water-to-oil weight ratio of (0.03-0.5):1.

[0089] In one embodiment, in the second reactor, the weight ratio of fresh catalyst to regenerated catalyst is 0.01-0.3:1; and / or

[0090] The reaction conditions for the difficult-to-convert component are: a reaction temperature of 560-720℃ and / or a reaction time of 0.1-3 seconds.

[0091] 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.

[0092] 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.

[0093] 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 height of the dense phase reaction zone, 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.

[0094] In one embodiment, the catalyst of this application 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.

[0095] 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.

[0096] 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.

[0097] 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.

[0098] 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.

[0099] 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.

[0100] In one embodiment, the regeneration conditions of the regenerator include:

[0101] Temperature 550-700℃, preferably 600-650℃;

[0102] The apparent linear velocity of the gas is 0.2-1.2 m / s, preferably 0.4-0.8 m / s; and / or

[0103] The average residence time of the catalyst is 1-10 minutes, preferably 2-6 minutes.

[0104] In one embodiment, the CO concentration in the regeneration flue gas of the regenerator is 0.5-6% by volume.

[0105] In one embodiment, the carbon content on the regenerated catalyst is 0.06-0.5% by weight.

[0106] According to this application, crude oil distillation into light and heavy fractions is a process well known to those skilled in the art. The separation of catalytic cracking reaction products from the spent catalyst is also well known to those skilled in the art; for example, it can be carried out using a cyclone separator in a settling tank. Further separation of the reaction oil and gas to obtain dry gas, liquefied petroleum gas (LPG), light distillate oil from difficult-to-convert components, and cracked heavy oil is also well known to those skilled in the art. The dry gas and LPG can be further separated using conventional separation methods in the art to obtain target products such as ethylene and propylene, as well as C4 components.

[0107] The present invention also provides a catalytic cracking system, comprising:

[0108] The crude oil distillation unit is used to separate crude oil into light and heavy fractions.

[0109] The catalytic cracking reaction unit includes:

[0110] The first reactor is provided with a first pre-lifting medium inlet, a first regeneration catalyst inlet, a supplementary catalyst inlet, a crude oil heavy fraction inlet, and a first oil-agent mixture outlet;

[0111] The second reactor is provided with a catalyst mixing zone, a crude oil light fraction inlet, a difficult-to-convert component inlet, and a second oil-agent mixture outlet in sequence. The catalyst mixing zone is provided with a second pre-lifting medium inlet, a second regenerated catalyst inlet, and a fresh catalyst inlet, which are used to mix the regenerated catalyst and fresh catalyst recycled back to the second reactor.

[0112] An oil-liquid separation device is used to separate a first oil-liquid mixture from a first reactor and a second oil-liquid mixture from a second reactor into reaction oil gas and a catalyst to be generated; and

[0113] 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.

[0114] Preferably, the first reactor and the second reactor are arranged side by side;

[0115] A reaction product separation unit, connected to an oil separation device, is used to separate the reaction oil and gas separated by the oil separation device; and

[0116] 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 catalyst outlet. The catalyst inlet of the regenerator is in fluid communication with the catalyst outlet of the stripping section. One catalyst outlet is connected to the catalyst inlet of the first reactor for recycling a portion of the catalyst back to the first reactor. Another catalyst outlet is connected to the catalyst inlet of the second reactor for recycling a portion of the catalyst back to the first reactor.

[0117] In one embodiment, the catalyst mixing zone is arranged coaxially with the second reactor.

[0118] In one embodiment, the first reactor is provided with one or more supplementary catalyst inlets, each of which is independently located at a height greater than 0% to 90% of the total height of the first reactor, 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.

[0119] The total height of the first reactor is the total height from the crude oil heavy fraction inlet to the first oil-liquid mixture outlet. The total height of the first reactor is... Figure 1 The symbol is marked H1. 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 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 and a distribution pipe. Preferably, the distribution pipe is an annular distribution pipe and a tree-shaped distribution pipe.

[0120] 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.

[0121] The following embodiments will further illustrate this application, but do not limit this application.

[0122] The feedstock used in the following examples and comparative examples is imported crude oil, which is an intermediate-base crude oil sourced from a branch of Sinopec. Its properties are shown in Table 1. The crude oil is distilled at its true boiling point with a cut point of 300°C to obtain light and heavy fractions of crude oil. The weight ratio of light to heavy fractions is 1:9. The catalyst used is a commercial catalytic cracking catalyst purchased from the Catalyst Division of China Petroleum & Chemical Corporation, with the brand name DMMC-2.

[0123] Example 1

[0124] 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:

[0125] The first reactor (fluidized bed reactor) has a total height of 7 meters and an inner diameter of 0.3 meters. The second reactor (dilute phase transport bed reactor) has a height of 7 meters and an inner diameter of 0.2 meters. The catalyst mixing zone has a height of 1 meter.

[0126] Crude oil is distilled into light and heavy fractions, with a distillation cutoff point of 300°C. The hot-regenerated catalyst in the regenerated inclined tube 103 enters the lower part of the first reactor and moves upwards under the action of the pre-lifting medium. Preheated heavy crude oil fraction and atomized steam are injected into the lower part of the first reactor through the feed line, mixing and contacting with the existing catalyst in the catalytic cracking reactor to undergo catalytic cracking. The post-reaction stream enters subsequent oil-catalyst separation and product separation equipment. A hot-regenerated catalyst is added to the first reactor at a height of 50% of the reactor's height, with the amount of added regenerated catalyst accounting for 10% by weight of the reactor's catalyst circulation.

[0127] The hot-regenerated catalyst from the regenerated inclined tube 303 and the fresh catalyst from the fresh catalyst inlet 302 enter the catalyst mixing zone 306. Under the lifting action of the pre-lifting medium injected through the second pre-lifting medium inlet 301, they move upward. The light fraction of crude oil enters the outlet of the catalyst mixing zone 306 through the inlet 304. The water-oil weight ratio is 0.2:1. It contacts the mixed catalyst and undergoes a catalytic cracking reaction. The reaction oil-catalyst mixture moves upward and contacts the difficult-to-convert components introduced downstream of the second reactor, continuing the catalytic cracking reaction.

[0128] 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.

[0129] The catalyst containing coke enters the regenerator, where it undergoes incomplete combustion upon contact with air. The regenerated catalyst is then returned to the first and second reactors for reuse in the reaction cycle. The regenerated flue gas enters the energy recovery system via the regenerated flue gas pipeline 405.

[0130] 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 45.60% by weight, and correspondingly, the total selectivity for low-carbon olefins and light aromatics reached 56.50% by weight.

[0131] Comparative Example 1

[0132] Using the feedstock and DMMC-2 catalyst shown in Table 1, experiments were conducted on a medium-sized unit. The reactor was a conventional riser reactor connected in series with a fluidized bed 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 subsequent oil-catalyst separation and product separation equipment. 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.

[0133] 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.

[0134] 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.

[0135] 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.

[0136] 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.

[0137] 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.

[0138] 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.

[0139] 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.

[0140] Properties of the crude oil used (Table 1)

[0141] 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

[0142] Table 2 Reaction conditions of Example 1 and Comparative Example 1

[0143]

[0144]

[0145] Table 3 Comparison of reaction results between Example 1 and Comparative Example 1

[0146] Example 1 Comparative Example 1 Product distribution, weight % gas 50.8 40.36 ethylene 6.98 3.97 Among them, propylene 19.96 16.51 Butene 11.97 10.59 liquid 41.92 49.86 Among them, light aromatics 6.68 4.22 total 100.00 100.00 Conversion rate, % 80.71 77.71 Yields of low-carbon olefins and light aromatics, % 45.60 35.28 Low carbon olefins and light aromatics selectivity, % 56.50 45.40

Claims

1. A method for producing low-carbon olefins and aromatics by catalytic cracking of inferior crude oil, comprising: (1) The crude oil is distilled and cut into light crude oil fraction and heavy crude oil fraction, wherein the cutting point of the light crude oil fraction and the heavy crude oil fraction is in the range of 280-360℃; (2) The crude oil heavy fraction and the first regeneration catalyst from the regenerator enter the first reactor for catalytic cracking reaction; (3) The second regenerated catalyst and the fresh catalyst are mixed in the catalyst mixing zone at the bottom of the second reactor to obtain a catalyst mixture. The catalyst mixture flows downstream of the second reactor under the action of the fluidizing medium and contacts the light fraction of crude oil and the difficult-to-convert components fed into the second reactor in sequence to undergo a cracking reaction. (4) The mixture of the reaction products from the first reactor and the second reactor and the catalyst to be generated enters 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. (5) The separated, coke-containing spent catalyst is stripped and then sent to a regenerator for oxygen-containing regeneration. The resulting regenerated catalyst is returned to the first and second reactors for use in the reaction cycle. The crude oil is selected from one or more of intermediate-based crude oil, intermediate-cycloalkyl crude oil, and cycloalkyl-intermediate crude oil, and the difficult-to-convert components are C4 components and / or light distillate oils with a final boiling point of less than 280-360℃. The regeneration conditions of the regenerator include: Temperature 550-700℃; The apparent linear velocity of the gas is 0.2-1.2 m / s; The average residence time of the catalyst is 1-10 minutes; The CO concentration in the regeneration flue gas from the regenerator is 0.5-6% by volume. The carbon content on the regenerated catalyst is 0.06%. 0.5% by weight 2. The method according to claim 1, characterized in that, In step (2), the reaction product comes into contact with the introduced supplementary catalyst and the reaction continues.

3. The method according to claim 1, characterized in that, The crude oil meets at least one of the following properties: characteristic factor K value not greater than 12.2, density of 800-935 kg / m³. 3 The residual carbon content is 2-10% by weight, and the total nickel and vanadium content is 5-50 ppm.

4. 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.

5. The method according to claim 4, characterized in that, The difficult-to-convert component is a gaseous hydrocarbon rich in C4 fraction produced by the unit itself.

6. 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.

7. The method according to claim 6, 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.

8. The method according to claim 1, characterized in that, The reaction conditions in the first reactor include: a reaction temperature of 510-650℃ and a weight hourly space velocity of 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.

9. The method according to claim 8, characterized in that, The crude oil heavy fraction is atomized with steam and then enters the first reactor, with a water-to-oil weight ratio of (0.03-0.8):

1.

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

11. The method according to claim 8, characterized in that, The light fraction of crude oil is atomized by steam and then enters the second reactor, with a water-to-oil weight ratio of (0.03-0.5):

1.

12. The method according to claim 1, characterized in that, In the second reactor, the weight ratio of fresh catalyst to regenerated catalyst is 0.01-0.3:1; and / or The reaction conditions for the difficult-to-convert component are: a reaction temperature of 560-720℃ and / or a reaction time of 0.1-3 seconds.

13. The method according to claim 1, characterized in that, The regeneration conditions of the regenerator include: The temperature is 600-650℃; The apparent gas velocity is 0.4–0.8 m / s; and / or The average residence time of the catalyst is 2-6 minutes.

14. A catalytic cracking system, comprising: The crude oil distillation unit is used to separate crude oil into light and heavy fractions. The catalytic cracking reaction unit includes: The first reactor is provided with a first pre-lifting medium inlet, a first regeneration catalyst inlet, a supplementary catalyst inlet, a crude oil heavy fraction inlet, and a first oil-agent mixture outlet; The second reactor is provided with a catalyst mixing zone, a crude oil light fraction inlet, a difficult-to-convert component inlet, and a second oil-agent mixture outlet in sequence. The catalyst mixing zone is provided with a second pre-lifting medium inlet, a second regenerated catalyst inlet, and a fresh catalyst inlet, which are used to mix the regenerated catalyst and fresh catalyst recycled back to the second reactor. An oil-liquid separation device is used to separate a first oil-liquid mixture from a first reactor and a second oil-liquid mixture from a second reactor into reaction oil gas and a 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, connected to an oil separation device, is used to separate the reaction oil and gas separated by the oil separation device; and 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 catalyst outlet. The catalyst inlet of the regenerator is in fluid communication with the catalyst outlet of the stripping section. One catalyst outlet is connected to the catalyst inlet of the first reactor for recycling a portion of the catalyst back to the first reactor. Another catalyst outlet is connected to the catalyst inlet of the second reactor for recycling a portion of the catalyst back to the first reactor.

15. The system according to claim 14, characterized in that, The first reactor and the second reactor are arranged side by side.

16. The system according to claim 14, characterized in that, The first reactor is provided with one or more supplementary catalyst inlets, each of which is independently located at a height greater than 0% to 90% of the total height of the first reactor.

17. The system according to claim 16, 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.

18. The system according to claim 17, 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.

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