A process and system for selective separation-catalytic cracking of crude oil

Abstract

The present application relates to a kind of crude oil selective separation-catalytic cracking process method, system, process method includes (1) making crude oil distillation cutting, obtain light oil, intermediate oil and heavy oil;(2) make intermediate oil first separation, obtain first saturated component and first unsaturated component;(3) make heavy oil second separation, obtain second saturated component and second unsaturated component;(4) make catalytic cracking raw material and catalyst contact and carry out catalytic cracking reaction, after oil-gas separation, obtain cracking gas, cracking light gasoline, cracking heavy gasoline, cracking diesel and cracking heavy oil;Catalytic cracking raw material includes light oil, first saturated component, second saturated component and optional difficult conversion component, difficult conversion component includes light hydrocarbon and / or light distillate oil.The present application makes crude oil distillation cutting and then carries out selective separation, selects specific catalytic cracking raw material and carries out catalytic cracking reaction, to make inferior crude oil better conversion into low carbon olefin and light aromatic hydrocarbon and other high-value products.

Description

Technical Field

[0001] This invention relates to the field of petrochemical technology, specifically to a process and system for selective separation and catalytic cracking of crude oil. Background Technology

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

[0003] ExxonMobil is a pioneer in the research and development of crude oil steam cracking to olefins, and was the first company to build an industrial-scale demonstration plant. It has also applied for a series of patents, such as CN200580016314.X. The company's direct olefins process involves crude oil directly entering a steam cracker, where it undergoes flash evaporation to separate light and heavy components. The light components (gaseous components) are then further cracked in the steam cracker, while the heavy components (liquid components) are used as feedstock for refineries. If the selected crude oil is sufficiently light and has no fractions above 593°C (i.e., no bottom residue), it can be produced without relying on a refinery. The company's first industrial-scale plant used ultralight paraffinic Tapis crude oil with an API gravity of 42.7 as feedstock.

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

[0005] Due to the presence of heavy components in crude oil that are difficult to vaporize, existing crude oil-to-chemicals technologies are only suitable for low-sulfur paraffin-based crude oils with an API gravity of around 45. Other crude oil-to-chemicals technologies vary among companies depending on the processing methods for heavy components in the crude oil, but they all employ fractionation, combining processes based on the properties of distillate oils at different boiling points to produce chemicals. Compared to traditional refining processes, this only changes the boiling point and quantity of the fractionated oils and integrates existing processing techniques, failing to achieve a fundamental technological revolution. Furthermore, these existing combined technologies are more suitable for light crude oils or paraffin-based crude oils; when using inferior crude oils such as heavy crude oils or intermediate-base crude oils as feedstock, the yield of high-value-added products and other chemicals is low.

[0006] How to better convert crude oil into high-value products such as low-carbon olefins and light aromatics, so as to significantly increase the yield of high-value products, is a technical problem that urgently needs to be solved. Summary of the Invention

[0007] This invention provides a process and system for selective separation and catalytic cracking of crude oil. The purpose is to selectively separate crude oil and then select specific catalytic cracking feedstocks for catalytic cracking reactions, so as to better convert inferior crude oil into high-value products such as low-carbon olefins and light aromatics.

[0008] In a first aspect, the present invention relates to a process for selective separation-catalytic cracking of crude oil, the process comprising the following steps:

[0009] (1) Distilling crude oil to obtain light oil, intermediate oil and heavy oil; wherein the cutting point of the light oil and the intermediate oil is 160-220℃, and the cutting point of the intermediate oil and the heavy oil is 260-320℃.

[0010] (2) The intermediate oil is subjected to a first separation to obtain a first saturated fraction and a first unsaturated fraction;

[0011] (3) The heavy oil is subjected to a second separation to obtain a second saturated fraction and a second unsaturated fraction;

[0012] (4) The catalytic cracking feedstock is brought into contact with the catalyst to carry out the catalytic cracking reaction, and the cracked gas, cracked light gasoline, cracked heavy gasoline, cracked diesel and cracked heavy oil are obtained by oil-gas separation;

[0013] The catalytic cracking feedstock comprises the light oil, the first saturated fraction, the second saturated fraction, and an optional difficult-to-convert component, wherein the difficult-to-convert component includes light hydrocarbons and / or light distillate oil.

[0014] In a second aspect, the present invention relates to a system for selective separation-catalytic cracking of crude oil, the system comprising a distillation unit, a first separation unit, a second separation unit, and a catalytic cracking reaction unit;

[0015] The distillation unit is equipped with a crude oil inlet, a light distillate oil outlet, a middle distillate oil outlet, and a heavy distillate oil outlet.

[0016] The middle distillate oil outlet of the distillation unit is connected to the material inlet of the first separation unit. The first separation unit is also provided with a first saturated outlet and a first unsaturated outlet.

[0017] The heavy distillate oil outlet of the distillation unit is connected to the material inlet of the second separation unit. The second separation unit is also provided with a second saturated outlet and a second unsaturated outlet.

[0018] The light distillate oil outlet, the first saturated outlet, and the second saturated outlet are respectively connected to the catalytic cracking feedstock inlet of the catalytic cracking reaction unit; the catalytic cracking reaction unit is also provided with a cracked gas outlet, a cracked light gasoline outlet, a cracked heavy gasoline outlet, a cracked diesel outlet, and a cracked heavy oil outlet.

[0019] Beneficial effects:

[0020] 1) It has strong adaptability to crude oil. By using a combination of crude oil component separation and catalytic cracking units, it can convert low-quality intermediate base crude oil into high-value-added products.

[0021] 2) High crude oil utilization rate: Due to the large differences in the size and structure of aromatics in the distillate oils of different distillation ranges of inferior crude oil, components with different hydrocarbon compositions can be selectively separated according to the properties of crude oil distillate oils. Targeted and selective catalytic conversion based on the characteristics of the components can improve the selectivity of the process and achieve efficient utilization of crude oil.

[0022] 3) High yield of high value-added products: Unsaturated fractions rich in aromatics in middle distillate oil can be directly used as aromatic components or high-octane gasoline blending components; unsaturated fractions rich in polycyclic aromatics or asphaltenes in heavy distillate oil can be used as needle coke or road asphalt feedstock depending on their properties; saturated fractions are used as catalytic cracking feedstock to be converted into low-carbon olefins and aromatics. The yield of high value-added products in the whole process reaches more than 65%.

[0023] 4) The unit has a high online rate. Inferior crude oil has a high content of residual carbon, high metals and high asphaltene. After component separation, the quality of catalytic cracking feedstock is greatly improved. Not only is the yield of target products high, but the operating cycle is also extended and the online rate is improved, thereby effectively improving economic benefits.

[0024] The crude oil selective separation-catalytic cracking process or system described in this application can efficiently produce low-carbon olefins and light aromatics from inferior crude oil. This not only produces high-value chemical raw materials and promotes the deep integration of the refining and petrochemical industries, but also effectively addresses the challenges brought about by the scarcity of petroleum resources. Furthermore, it not only has good crude oil adaptability and high chemical yield, but also produces other high-value-added chemical raw materials as byproducts, resulting in high crude oil utilization. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of a specific embodiment of a crude oil selective separation-catalytic cracking system according to the present invention;

[0026] Explanation of reference numerals in the attached figures

[0027] 100 Distillation Unit 101 Crude Oil Inlet 201a Light Distillate Oil Outlet

[0028] 202 First Separation Unit 202a Middle Distillate Oil Outlet 202b First Saturated Distillate Outlet

[0029] 202c First unsaturated fraction outlet; 203 Second separation unit; 203a Heavy distillate oil outlet.

[0030] 203b Second saturated outlet 203c Second unsaturated outlet 300 Hydrogenation reaction unit

[0031] 301 Hydrogenation product outlet; 400 Catalytic cracking reaction unit; 401 Cracking gas outlet

[0032] 402 Cracked Light Gasoline Export; 403 Cracked Heavy Gasoline Export; 404 Cracked Diesel Export

[0033] 405 Cracking Heavy Oil Outlet, 406 Difficult-to-Convert Components Inlet Detailed Implementation

[0034] 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.

[0035] 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.

[0036] 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.

[0037] In a first aspect, the present invention relates to a process for selective separation-catalytic cracking of crude oil, the process comprising the following steps:

[0038] (1) Distilling crude oil to obtain light oil, intermediate oil and heavy oil; wherein the cutting point of the light oil and the intermediate oil is 160-220℃, and the cutting point of the intermediate oil and the heavy oil is 260-320℃.

[0039] (2) The intermediate oil is subjected to a first separation to obtain a first saturated fraction and a first unsaturated fraction;

[0040] (3) The heavy oil is subjected to a second separation to obtain a second saturated fraction and a second unsaturated fraction;

[0041] (4) The catalytic cracking feedstock is brought into contact with the catalyst to carry out the catalytic cracking reaction, and the cracked gas, cracked light gasoline, cracked heavy gasoline, cracked diesel and cracked heavy oil are obtained by oil-gas separation;

[0042] The catalytic cracking feedstock comprises the light oil, the first saturated fraction, the second saturated fraction, and an optional difficult-to-convert component, wherein the difficult-to-convert component includes light hydrocarbons and / or light distillate oil.

[0043] It should be noted that in step (1), "distillation cutting" can mean separation by distillation, and the cutting point indicates the temperature at which the oil is heated during distillation separation. The cutting points for light oil and intermediate oil can be 170℃, 175℃, 180℃, 185℃, 190℃, 195℃, 200℃, 205℃, 210℃, 215℃, etc., while the cutting points for intermediate oil and heavy oil can be 265℃, 270℃, 275℃, 280℃, 285℃, 290℃, 300℃, 305℃, 310℃, 315℃, etc.

[0044] It should be noted that in the process method of this application, in step (1), crude oil is distilled and separated into light, medium and heavy fractions according to different distillation ranges or boiling points. Preferably, it is cut according to the above-mentioned cutting points to obtain light oil, medium oil and heavy oil. In steps (2) and (3), the medium oil and heavy oil are separated into components to obtain saturated and unsaturated fractions respectively. The obtained saturated fraction is rich in saturated hydrocarbons and the obtained unsaturated fraction is rich in aromatics. The light oil obtained from step (1) is not separated. In step (4), the light oil obtained from step (1) and the saturated fractions rich in alkanes and cycloalkanes obtained from steps (2) and (3) are used as raw materials for catalytic cracking. Catalytic cracking reaction occurs under high temperature and the catalytic action of catalyst. The reaction products can be separated to obtain high-value products such as low-carbon olefins and light aromatics.

[0045] It should be noted that "optional difficult-to-convert components" means that the catalytic cracking feedstock may or may not contain difficult-to-convert components, or may contain difficult-to-convert components in any proportion. The light hydrocarbons and / or light distillate oils of the difficult-to-convert components may be obtained from the process method of this application or introduced from external sources. Light distillate oil, middle distillate oil, and heavy distillate oil may be abbreviated as light oil, middle oil, and heavy oil, respectively.

[0046] The present invention first distills and separates crude oil according to the above-mentioned cutting points to obtain light oil, intermediate oil and heavy oil; then the intermediate oil and heavy oil are separated into saturated and unsaturated fractions respectively, and the two saturated fractions and light oil are used together as feedstock for catalytic cracking reaction.

[0047] Through years of research and development, the inventors of this application discovered a novel and scientific process: first, crude oil is distilled and separated; then, materials within a specific distillation range are selectively separated. The selectively separated saturated fraction and light oil are then used together as feedstock for catalytic cracking. This process enables crude oil to be better converted into high-value products such as low-carbon olefins and light aromatics, significantly increasing the yield of high-value-added products. In this application, the high-value-added product yield refers to the total yield of low-carbon olefins (ethylene, propylene, butene), light aromatics BTX (benzene, toluene, and xylene), the first unsaturated fraction, and the second unsaturated fraction.

[0048] It should be noted that after the catalytic cracking reaction in step (4), cracked gas, cracked light gasoline, cracked heavy gasoline, cracked diesel and cracked heavy oil are obtained through oil separation, oil-gas separation and other steps. The gaseous products, namely cracked gas, can be separated to obtain ethylene, propylene, butene and other products. The liquid products, such as cracked heavy gasoline, can be separated to obtain light aromatics such as BTX. The separation processes involved can be carried out using conventional separation methods in the field or methods well known to those skilled in the art.

[0049] According to a specific embodiment of the process method described in the first aspect of the present invention, the crude oil in step (1) is selected from one or more of the following: paraffin-based, paraffin-intermediate-based, intermediate-paraffin oil, intermediate-based crude oil, and intermediate-naphthenic crude oil; and / or

[0050] The crude oil meets at least one of the following criteria:

[0051] The density at 20℃ is 800-935 kg / m³. 3 API content less than 30, UOP K value not greater than 12.0, and metal content greater than 30 mg / kg.

[0052] It should be noted that intermediate-paraffinic crude oil can have two key components: the first key component is intermediate-based, and the second key component is paraffinic; paraffinic-intermediate crude oil can have two key components, where the first key component is paraffinic and the second key component is intermediate-based; either the first or second key component of intermediate-based crude oil is intermediate-based. The process method of this application can distill and selectively separate these inferior oils, allowing the saturated fraction and light oil to undergo catalytic cracking, thereby producing high-value products such as low-carbon olefins and light aromatics in high yields.

[0053] It should be noted that the inventors of this application have developed the crude oil selective separation-catalytic cracking process method of this application through years of research and development. This process method of this application has strong raw material adaptability, high yield of high value-added products, and can produce the above-mentioned high-value products well even with low-quality crude oil, so as to realize the efficient utilization of low-quality crude oil resources. Therefore, the process method of this application can be called the low-quality crude oil selective separation-catalytic cracking process method.

[0054] According to another specific embodiment of the process method described in the first aspect of the present invention, the first separation in step (2) includes: contacting the intermediate oil with an ionic liquid or a first solvent to perform a first extraction separation;

[0055] The thermal stability of the ionic liquid is higher than 250℃;

[0056] The ionic liquid comprises cations and anions; the cations are selected from alkyl-substituted imidazoles and / or pyridines; the anions are selected from at least one of hexafluorophosphate, tetrafluoroborate, and bis(trifluoromethanesulfonyl)imide.

[0057] The first solvent is selected from one or more combinations of furfural, dimethyl sulfoxide, N,N-dimethylformamide, N,N-diethylformamide and morpholine;

[0058] The conditions for the first extraction and separation include: a temperature of 15-120°C, a pressure of 0.1-0.5 MPa, and the weight ratio of the ionic liquid to the intermediate oil, or the weight ratio of the first solvent to the intermediate oil, is independently (1-15):1.

[0059] It should be noted that, in one embodiment, based on the weight of the first saturated fraction, the content of saturated hydrocarbons in the first saturated fraction obtained after the first separation can be 75-90% by weight. Using the aforementioned first solvent or ionic liquid and performing the first extraction separation under the aforementioned conditions allows the first separation process to proceed more effectively. The obtained first saturated fraction, together with the second saturated fraction and light oil, serves as feedstock for catalytic cracking, which is beneficial for further improving the yield of high-value-added products from catalytic cracking, and also results in low energy consumption.

[0060] According to a specific embodiment of the process method described in the first aspect of the present invention, the second separation in step (3) includes: contacting the heavy oil with a second solvent to perform supercritical extraction separation;

[0061] Wherein, the second solvent is selected from low-carbon alkanes; the low-carbon alkanes are selected from one or a mixture of several of ethane, propane, propylene, n-butane, isobutane, n-pentane, isopentane, hexane, heptane, and octane;

[0062] The conditions for supercritical extraction separation include: a temperature of 50-100℃, a pressure of 6-20 MPa, and a weight ratio of the second solvent to the heavy oil of (2-5):1.

[0063] It should be noted that, in one embodiment, based on the weight of the second saturated fraction obtained after the second separation, the content of saturated hydrocarbons in the second saturated fraction can be greater than 45% by weight. By using the second solvent described above and performing supercritical extraction separation under the above conditions, the obtained second saturated fraction, together with the first saturated fraction and light oil, is used as a catalytic cracking feedstock for the catalytic cracking reaction in step (4), which can obtain the above-mentioned high value-added product in a higher yield.

[0064] According to a specific embodiment of the process method described in the first aspect of the present invention, the process method further includes the following steps:

[0065] This allows the first unsaturated fraction from step (2) to be used as a feedstock for the production of high-octane gasoline and / or aromatics; and / or,

[0066] This allows the second unsaturated fraction from step (3) to be used as a raw material for the production of needle coke and / or road asphalt; and / or,

[0067] This allows the pyrolysis gas from step (4) to be separated to obtain ethylene, propylene, butene and the remaining components.

[0068] It should be noted that the separation method for obtaining ethylene, propylene, butene and the remaining components from the pyrolysis gas obtained in step (4) can be any conventional separation method in the art or any method known to those skilled in the art. This invention does not limit the method.

[0069] The process method developed by the inventors of this application through years of research and experimentation, through distillation, cutting and selective separation, not only uses light oil, the first saturated fraction and the second saturated fraction as raw materials, but also obtains high-value products with significantly improved yield through catalytic cracking reaction. Furthermore, the obtained first unsaturated fraction and the second unsaturated fraction can be used as raw materials for the production of high-octane gasoline and / or aromatics, and for the production of needle coke and / or road asphalt. Both the saturated and unsaturated fractions in crude oil can be well converted or utilized, and the crude oil utilization rate is significantly improved.

[0070] According to another specific embodiment of the process method described in the first aspect of the present invention, the light hydrocarbon of the difficult-to-convert component includes gaseous hydrocarbon products rich in C4 fractions, preferably including butene obtained by separating the cracked gas;

[0071] The light distillate oils containing difficult-to-convert components include self-produced light distillate oils with a final boiling point of less than 280-360℃ 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.

[0072] And / or, the light distillate oil of the difficult-to-convert components preferably includes the cracked light gasoline obtained from step (4);

[0073] The weight percentages of butene and cracked light gasoline, which are the difficult-to-convert components, in the catalytic cracking feedstock are each 5-20%.

[0074] It should be noted that, in this preferred embodiment, the catalytic cracking feedstock in step (4) includes not only light oil, the first saturated component, and the second saturated component, but also a difficult-to-convert component. The difficult-to-convert component may include butene obtained from the separation of cracked gas and / or the cracked light gasoline obtained from oil-gas separation. Through years of research and development experiments, the inventors of this application have discovered that using the difficult-to-convert component together with the above two saturated components and light oil as catalytic cracking feedstock for the catalytic cracking reaction in step (4) is beneficial for better conversion of the catalytic cracking feedstock into high-value products such as low-carbon olefins (ethylene, propylene, butene) and light aromatics BTX (benzene, toluene, and xylene), thereby further improving the yield of high-value-added products. In the catalytic cracking feedstock, the weight percentage of the difficult-to-convert component can be 8%, 10%, 12%, and 15%, etc. The percentage of butene or cracked light gasoline as the difficult-to-convert component in the catalytic cracking feedstock is based on the amount of the catalytic cracking feedstock excluding the difficult-to-convert component.

[0075] It should be noted that the light hydrocarbons of the difficult-to-convert components may include gaseous hydrocarbon products rich in C4 fractions produced by the process method of this application and gaseous hydrocarbons rich in C4 fractions produced by other equipment processes, preferably C4 fractions or butene produced by the process method of this application. The light distillate oils of the difficult-to-convert components may include light distillate oils with a final boiling point of less than 280-360℃ produced by the process method of this application, or one or more of the above-mentioned straight-run naphtha, straight-run kerosene, etc., introduced from other external processes or equipment, such as one or more of the following mixtures of primary processed straight-run naphtha, straight-run kerosene, and straight-run diesel; and one or more of the following 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.

[0076] It should be noted that, in one embodiment, the light hydrocarbons in the difficult-to-convert component are C4 components. These C4 components refer to low-molecular-weight hydrocarbons existing in gaseous form at room temperature and pressure, with C4 fractions as the main component. They include alkanes, alkenes, and alkynes with four carbon atoms in their molecules. This includes gaseous hydrocarbon products rich in C4 fractions produced by the process of this invention, and may also include gaseous hydrocarbons rich in C4 fractions produced by other processes, with the C4 fraction produced by the process 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.

[0077] According to a specific embodiment of the process method described in the first aspect of the present invention, the process method further includes the following steps:

[0078] This causes the first unsaturated fraction from step (2) to undergo a hydrogenation reaction, resulting in a hydrogenated first unsaturated fraction.

[0079] The catalytic cracking feedstock in step (4) also includes the first unsaturated hydrogenation fraction;

[0080] The first unsaturated hydrogenated fraction accounts for 0.1-10% by weight of the catalytic cracking feedstock.

[0081] It should be noted that, as a preferred embodiment, the first unsaturated fraction from step (2) undergoes a hydrogenation reaction under the action of hydrogen and a hydrogenation catalyst to obtain a hydrogenated component, namely the hydrogenated first unsaturated fraction. The hydrogenated first unsaturated fraction can be used together with the light oil, the first saturated fraction, the second saturated fraction, and the difficult-to-convert component as feedstock for the catalytic cracking reaction in step (4), or the hydrogenated first unsaturated fraction can be used as feedstock for producing high-octane gasoline components or aromatic components. In this preferred embodiment, in step (4), the catalytic cracking feedstock includes light oil, the first saturated fraction, the second saturated fraction, butene obtained from gas product separation, cracked light gasoline obtained from oil-gas separation, and the hydrogenated first unsaturated fraction obtained from the first unsaturated fraction from step (2) through a hydrogenation reaction. The catalytic cracking feedstock composed in this way can better prepare high-value products through catalytic cracking reaction, and further improve the yield of high-value products. The weight percentage of the hydrogenated first unsaturated fraction in the catalytic cracking feedstock can be 1%, 1.5%, 2%, 3%, and 5%, etc.

[0082] It should be noted that, in this embodiment, the conditions for the hydrogenation reaction of the first unsaturated fraction obtained from step (2) include a hydrogen partial pressure of 10.0-25.0 MPa, a reaction temperature of 330-450 °C, and a volume hourly space velocity of 0.1-2.0 h⁻¹. -1 Hydrogen-to-oil volume ratio 1000-2000 Nm 3 / m 3 The active metal component in the hydrogenation catalyst is selected from Group VIB metals and / or Group VIII non-noble metals, and the support is selected from one or more of alumina, silica, and amorphous silica-alumina. The Group VIB metal is molybdenum and / or tungsten, and the Group VIII non-noble metal is nickel and / or cobalt. The active metal component is preferably a combination of one or more of nickel-tungsten, nickel-tungsten-cobalt, nickel-molybdenum, or cobalt-molybdenum.

[0083] According to a specific embodiment of the process method described in the first aspect of the present invention, the conditions for the catalytic cracking reaction in step (4) include:

[0084] The catalytic cracking feedstock is mixed with steam and then fed into the reactor. The reaction temperature is 510-650℃, the reaction time is 1-20 seconds, the weight ratio of the catalyst to the catalytic cracking feedstock is (3-50):1, and the weight ratio of the steam to the catalytic cracking feedstock is (0.03-0.8):1; and / or,

[0085] The catalyst comprises the following components, based on a dry weight basis:

[0086] 1-50 wt% zeolite, 5-99 wt% inorganic oxides, and 0-70 wt% clay;

[0087] Preferably, it contains 5-45% zeolite, 10-80% inorganic oxides, and 5-60% clay;

[0088] More preferably, 10-40% by weight zeolite, 20-70% by weight inorganic oxides, and 10-50% by weight clay.

[0089] It should be noted that, in one embodiment, the zeolite includes mesoporous zeolite and optionally macroporous zeolite. The mesoporous zeolite is selected from ZSM series zeolites, ZRP zeolite, and any combination thereof; 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. 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 zeolite may also 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. ZSM series zeolites are preferably selected from one or more 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 U.S. Patent 3,702,886A.

[0090] In one embodiment, the mesoporous zeolite accounts for 10-90% by weight, preferably 50-80% by weight, on a dry basis, of the total weight of the zeolite. In this application, the mesoporous and macroporous zeolites are defined according to conventional art, i.e., the average pore size of the mesoporous zeolite is about 0.5-0.6 nm, and the average pore size of the macroporous zeolite is about 0.7-1.0 nm. The inorganic oxide, used as a binder, is preferably silicon dioxide (SiO2) and / or aluminum oxide (Al2O3). The clay, used as a matrix (i.e., carrier), is preferably kaolin and / or hydrous kaolin.

[0091] It should be noted that, in the process method of this application, by controlling the conditions of the catalytic cracking reaction in step (4) as described above, the catalytic cracking feedstock can be better reacted into high-value products such as low-carbon olefins (ethylene, propylene, butene) and light aromatics BTX (benzene, toluene and xylene) under the catalysis of the above catalyst, and the yield of high-value-added products can be further improved.

[0092] Secondly, the present invention relates to a system for selective separation-catalytic cracking of crude oil, such as... Figure 1As shown, the system includes a distillation unit 100, a first separation unit 202, a second separation unit 203, and a catalytic cracking reaction unit 400;

[0093] The distillation unit 100 is provided with a crude oil inlet 101, a light distillate oil outlet 201a, a middle distillate oil outlet 202a and a heavy distillate oil outlet 203a.

[0094] The middle distillate oil outlet 202a of the distillation unit 100 is connected to the material inlet of the first separation unit 202. The first separation unit 202 is also provided with a first saturated outlet 202b and a first unsaturated outlet 202c.

[0095] The heavy distillate oil outlet 203a of the distillation unit 100 is connected to the material inlet of the second separation unit 203. The second separation unit 203 is also provided with a second saturated outlet 203b and a second unsaturated outlet 203c.

[0096] The light distillate oil outlet 201a, the first saturated fraction outlet 202b, and the second saturated fraction outlet 203b are respectively connected to the catalytic cracking feedstock inlet of the catalytic cracking reaction unit 400; the catalytic cracking reaction unit 400 is also provided with a cracked gas outlet 401, a cracked light gasoline outlet 402, a cracked heavy gasoline outlet 403, a cracked diesel outlet 404, and a cracked heavy oil outlet 405.

[0097] It should be noted that the process method described in the first aspect of the present invention can be based on, but is not limited to, the system described in the second aspect of the present invention, and the system described in the second aspect of the present invention can be operated based on, but is not limited to, the process method described in the first aspect of the present invention.

[0098] It should be noted that in the system of this application, crude oil enters the distillation unit 100 through crude oil inlet 101, and is distilled to obtain light distillate oil, middle distillate oil, and heavy distillate oil. The three types of oils obtained from the distillation process flow out of the distillation unit 100 through light distillate oil outlet 201a, middle distillate oil outlet 202a, and heavy distillate oil outlet 203a, respectively. Then, the light distillate oil enters the catalytic cracking reaction unit, the middle distillate oil enters the first separation unit 202, and the heavy distillate oil enters the second separation unit 203. The middle distillate oil and the heavy distillate oil are separated in the two separation units, respectively. Specifically, the middle distillate oil is separated into a first saturated fraction and a first unsaturated fraction in the first separation unit 202, and the heavy distillate oil is separated into a second saturated fraction and a second unsaturated fraction in the second separation unit 203. The first saturated fraction flows out through the first saturated fraction outlet 202b and then enters the catalytic cracking reaction unit 400 through the catalytic cracking feedstock inlet. The second saturated fraction flows out through the second saturated fraction outlet 203b and then enters the catalytic cracking reaction unit 400 through the catalytic cracking feedstock inlet. The light distillate oil and the two saturated fractions are used as catalytic cracking feedstocks and are in contact with the catalyst in the catalytic cracking reaction unit 400 to carry out catalytic cracking reaction at high temperature. They are then separated by oil-agent separation equipment and oil-gas separation equipment to obtain cracked gas, cracked light gasoline, cracked heavy gasoline, cracked diesel, and cracked heavy oil. The above products flow out through cracked gas outlet 401, cracked light gasoline outlet 402, cracked heavy gasoline outlet 403, cracked diesel outlet 404, and cracked heavy oil outlet 405, respectively.

[0099] It should be noted that the system of this application first distills and cuts the feedstock oil through the distillation unit 100. The light distillate oil obtained from the distillation and cutting is directly fed into the catalytic cracking reaction unit 400 without separation. The middle distillate oil and heavy distillate oil obtained from the distillation and cutting are separated in the first separation unit 202 and the second separation unit 203, respectively. The first saturated fraction and the second saturated fraction obtained from the separation are fed into the catalytic cracking reaction unit 400. The light distillate oil, the first saturated fraction and the second saturated fraction are used together as catalytic cracking feedstock in the catalytic cracking reaction unit 400 to carry out catalytic cracking, so that the crude oil can be better converted into high-value products such as low-carbon olefins (ethylene, propylene, butene) and light aromatics BTX (benzene, toluene and xylene).

[0100] It should be noted that in the crude oil selective separation-catalytic cracking system of the present invention, oil-agent separation equipment and reaction product separation equipment may also be provided. The oil-agent separation equipment and reaction product separation equipment are well known to those skilled in the art. For example, the oil-agent separation equipment may include cyclone separators, settling tanks and strippers, while the reaction product separation equipment may be fractionation towers.

[0101] According to a specific embodiment of the system described in the second aspect of the present invention, the system is further provided with a high-octane gasoline production unit and / or an aromatics production unit, wherein the first unsaturated outlet 202c is connected to the feed inlet of the high-octane gasoline production unit and / or the feed inlet of the aromatics production unit.

[0102] And / or,

[0103] The system also includes a needle coke production unit and / or a road asphalt production unit, wherein the second unsaturated outlet 203c is connected to the raw material inlet of the needle coke production unit and / or the raw material inlet of the road asphalt production unit; and / or,

[0104] The system also includes a gas separation unit. The pyrolysis gas outlet 401 of the catalytic cracking reaction unit 400 is connected to the gas inlet to be separated of the gas separation unit. The gas separation unit is also provided with an ethylene outlet, a propylene outlet, a butene outlet and a residual component outlet.

[0105] It should be noted that the middle distillate oil is separated into a first saturated fraction and a first unsaturated fraction by the first separation unit 202. The resulting first unsaturated fraction flows out through the first unsaturated fraction outlet 202c and can be used as feedstock in the high-octane gasoline production unit to produce high-octane gasoline, or it can be used as feedstock in the aromatics production unit to produce aromatics. The heavy distillate oil is separated into a second saturated fraction and a second unsaturated fraction by the second separation unit 203. The resulting second unsaturated fraction flows out through the second unsaturated fraction outlet 203c and can be used as feedstock in the needle coke production unit to produce needle coke, or it can be used as feedstock in the road asphalt production unit to produce road asphalt.

[0106] It should be noted that the pyrolysis gas flowing out of the pyrolysis gas outlet 401 is separated into ethylene, propylene, butene and residual components by the gas separation unit.

[0107] The system of this application uses light distillate oil, first saturated fraction and second saturated fraction as raw materials to carry out catalytic cracking reaction in catalytic cracking reaction unit 400, which can better obtain high-value products. The two unsaturated fractions obtained by selective separation process can be used as raw materials for the production of aromatics, high octane gasoline, needle coke or road asphalt, which can make good use of various components contained in crude oil.

[0108] According to a specific embodiment of the system described in the second aspect of the present invention, the catalytic cracking reaction unit 400 is further provided with a difficult-to-convert component inlet 406, which is connected to the cracked light gasoline outlet 402 and / or the butene outlet of the gas separation unit.

[0109] It should be noted that, in a preferred embodiment, the cracked light gasoline flows out of the cracked light gasoline outlet 402 and then enters the catalytic cracking reaction unit 400 through the difficult-to-convert component inlet 406 as a catalytic cracking feedstock for the catalytic cracking reaction. The butene separated by the gas separation unit flows out of the butene outlet and then enters the catalytic cracking reaction unit 400 through the difficult-to-convert component inlet 406 as a catalytic cracking feedstock for the catalytic cracking reaction. Using the aforementioned butene and / or cracked light gasoline as partial catalytic cracking feedstock allows the catalytic cracking reaction to proceed more effectively and can further improve the yield of high-value products.

[0110] It should be noted that, as a variation of the implementation, the difficult-to-convert component inlet 406 can be connected to the gaseous hydrocarbon outlet rich in C4 fractions of other external units, or to the light distillate oil outlet with a final boiling point of less than 280-360°C of other external units. Specifically, it can be connected to one or more outlets of other primary processing units, such as straight-run naphtha outlet, straight-run kerosene outlet, and straight-run diesel outlet, or to one or more outlets of other secondary processing units, such as topping oil outlet, residue oil outlet, hydrocracking light naphtha outlet, pentane oil outlet, coking gasoline outlet, Fischer-Tropsch synthesis oil outlet, catalytic cracking light gasoline outlet, hydrotreated gasoline outlet, and hydrotreated diesel outlet.

[0111] 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.

[0112] It should be noted that there can be one, two, or more difficult-to-convert component inlets 406. In one embodiment, when there is one difficult-to-convert component inlet 406, light hydrocarbons and light distillate oils, which are difficult-to-convert components, can enter the catalytic cracking reaction unit through the same difficult-to-convert component inlet 406. In another preferred embodiment, there are two or more difficult-to-convert component inlets 406, and light hydrocarbons and light distillate oils, which are difficult-to-convert components, enter the catalytic cracking reactor through different difficult-to-convert component inlets 406. Specifically, light hydrocarbons are introduced into the catalytic cracking reactor through one or more difficult-to-convert component inlets 406 upstream of the light distillate oil difficult-to-convert component inlet 406 (introduction position), which is beneficial to obtain high-value products with higher yields.

[0113] It should be noted that, in one embodiment, the catalytic cracking reactor is provided with one or more, for example, one, two or more inlets for difficult-to-convert components, and the one or more inlets for difficult-to-convert components can be independently located in the lower part of the catalytic cracking reactor. More preferably, the inlets for difficult-to-convert components are each independently located in the middle and upper reaches of the catalytic cracking reactor.

[0114] It should be noted that, in one embodiment, the light distillate oil is introduced into the catalytic cracking reaction unit 400 through a light distillate oil inlet located upstream of one or more difficult-to-convert components.

[0115] According to another specific embodiment of the system described in the second aspect of the present invention, the system is further provided with a hydrogenation reaction unit 300, wherein the first unsaturated outlet 202c is connected to the hydrogenation feedstock inlet of the hydrogenation reaction unit 300, and the hydrogenation product outlet 301 of the hydrogenation reaction unit 300 is connected to the catalytic cracking feedstock inlet of the catalytic cracking reaction unit 400.

[0116] In a preferred embodiment, the middle distillate oil is separated into a first saturated fraction and a first unsaturated fraction in the first separation unit 202. The first unsaturated fraction enters the hydrogenation reaction unit 300, where it undergoes a hydrogenation reaction in the presence of hydrogen and a hydrogenation catalyst. The hydrogenated product of the first unsaturated fraction flows out through the hydrogenation product outlet 301 and is then used as feedstock for catalytic cracking in the catalytic cracking reaction unit 400 for catalytic cracking. In this preferred embodiment, the hydrogenated product of the first unsaturated fraction, together with the light distillate oil and the two saturated fractions (which may also include butene obtained from gas separation and cracked light gasoline obtained from oil-gas separation), is used as feedstock for catalytic cracking, which can further improve the yield of high-value products.

[0117] According to a specific embodiment of the process method described in the first aspect of the present invention, the first separation unit 202 is an extraction separation unit, and the second separation unit 203 is a supercritical extraction separation unit;

[0118] The catalytic cracking reaction unit 400 is selected from one or a combination of several reactors, including fluidized bed, turbulent bed, fast bed and dilute phase transport bed; the reactor is selected from one or a combination of two of the following: constant linear velocity reactor, constant diameter reactor, variable diameter reactor, upward transport line reactor and downward transport line reactor.

[0119] It should be noted that in the system of this application, an extraction separation unit and a supercritical extraction separation unit are used in combination, and the catalytic cracking reaction unit (reactor) is selected from the above-mentioned reactor, so that the separation process and the catalytic cracking reaction process can operate better, thereby improving the yield of high-value products of the system.

[0120] It should be noted that, in order to ensure the feedstock oil reacts fully and depending on the different quality requirements of the target product, the catalytic cracking reaction unit can have 2-8 reaction zones, preferably 2-3. The gas velocity in the turbulent bed and fast bed reactors is 0.1 m / s to 2 m / s, and the gas velocity in the dilute phase transport bed is 2 m / s to 20 m / s.

[0121] Figure 1A preferred embodiment of the crude oil selective separation-catalytic cracking system of this application is provided.

[0122] like Figure 1 As shown, crude oil enters the distillation unit 100 through crude oil inlet 101 and is separated into light distillate oil, middle distillate oil and heavy distillate oil under the action of heat;

[0123] The separated light distillate oil flows out through light distillate oil outlet 201a and then enters catalytic cracking reaction unit 400;

[0124] The separated middle distillate oil flows out through middle distillate oil outlet 202a and enters the first separation unit 202, where it contacts the extraction solvent and achieves component separation to obtain a first saturated fraction and a first unsaturated fraction. The first saturated fraction flows out through the first saturated fraction outlet 202b and enters the catalytic cracking reaction unit 400. The first unsaturated fraction flows out through the first unsaturated fraction outlet 202c and is used as a raw material for producing high-octane gasoline components or aromatic components. Optionally, the first unsaturated fraction flows out through the first unsaturated fraction outlet 202c and is sent to the hydrogenation reaction unit 300 for hydrogenation treatment under the action of hydrogen and hydrogenation catalyst. The resulting hydrogenated first unsaturated fraction flows out through the hydrogenation product outlet 301 and is sent to the catalytic cracking reaction unit 400.

[0125] The separated heavy distillate oil flows out through heavy distillate oil outlet 203a and enters the second separation unit 203, where it contacts the extraction solvent and achieves component separation to obtain a second saturated fraction and a second unsaturated fraction. The second saturated fraction flows out through the second saturated fraction outlet 203b and is sent to the catalytic cracking reaction unit 400; the second unsaturated fraction is sent out of the device through the second unsaturated fraction outlet 203c as a raw material for the production of needle coke or road asphalt.

[0126] The first saturated fraction from the first saturated fraction outlet 202b, the second saturated fraction from the second saturated fraction outlet 203b, and the light distillate oil from the light distillate oil outlet 201a of the distillation unit, along with optional recalcitrant components from the recalcitrant component inlet 406, enter the catalytic cracking reaction unit 400. Under the action of heat and the catalytic cracking catalyst, a catalytic cracking reaction occurs. The reaction products are separated to obtain cracked gas (cracked gas outlet 401), cracked light gasoline (cracked light gasoline outlet 402), cracked heavy gasoline (cracked heavy gasoline outlet 403), cracked diesel (cracked diesel outlet 404), and cracked heavy oil (cracked heavy oil outlet 405). Further separation of the cracked gas can yield ethylene, propylene, butene, and other products.

[0127] The present invention will be further described in detail below through examples, but these examples are not intended to limit the invention. In the following examples, unless otherwise specified, the experimental instruments and raw materials involved are all commercially available products.

[0128] The feedstock used in the following examples and comparative examples is Kuwaiti crude oil, the properties of which are shown in Table 1. The catalyst used in the catalytic cracking unit is a commercial catalytic cracking catalyst purchased from the Catalyst Division of China Petroleum & Chemical Corporation (Sinopec), with the trade name DMMC-2. The trade name of the hydrotreating catalyst is RN-32L.

[0129] Properties of the crude oil used (Table 1)

[0130] Crude oil classification intermediate base crude oil <![CDATA[Density (20 °C) / (kg / m 3 )]]> 887.5 UOP K value 11.9 Carbon content / weight % 84.33 Sulfur content / weight % 2.631 Nitrogen content / weight % 0.16 Residual carbon value / % by weight 6.29 Metal content (mg / kg) Fe 1.3 Ni 13 V 37 Na <0.1 Ca 0.2

[0131] The yield of high value-added products refers to the total yield of low-carbon olefins (ethylene, propylene, butene), light aromatics BTX (benzene, toluene, and xylene), components for producing aromatics or high-octane gasoline (first unsaturated fraction), and components for producing needle coke or road asphalt (second unsaturated fraction). The yield of a certain product can also refer to the weight percentage of that product in crude oil.

[0132] Example 1

[0133] like Figure 1 As shown in Table 1, Kuwaiti crude oil was separated into light distillate, middle distillate, and heavy distillate by true boiling point distillation. The cutoff point between the light distillate and the middle distillate was 200℃, and the cutoff point between the middle distillate and the heavy distillate was 300℃.

[0134] The middle distillate oil is extracted and separated in the first separation unit using an ionic liquid as the solvent. The cation is a dialkyl-substituted imidazole cation, the alkyl groups are methyl and hexyl, and the anion is a hexafluorophosphate anion to obtain a first saturated fraction and a first unsaturated fraction. The yield of the first saturated fraction is 83%, the mass fraction of saturated hydrocarbons in the first saturated fraction is 87.4%, and the mass fraction of aromatics in the first unsaturated fraction is 92.4%. It is a high-quality feedstock for producing high-octane gasoline components or aromatic components.

[0135] The heavy distillate oil is fed into the second separation unit where propane is used as a solvent. The second saturated fraction and the second unsaturated fraction are obtained by supercritical extraction. The yield of the second saturated fraction is 76.2%, the mass fraction of saturated hydrocarbons in the second saturated fraction is 52.4%, and the heavy metal removal rate is over 96%. The second unsaturated fraction can be used as a raw material for road asphalt.

[0136] Catalytic cracking experiments were conducted using a fluidized bed reactor for saturated fractions with different distillation ranges. Before the experiment, the catalyst was loaded into the reactor and kept in a fluidized state while the reactor was heated to the reaction temperature. The catalytic cracking feedstock, including light distillate oil, first saturated fraction, second saturated fraction, and recalcitrant light gasoline (obtained from cracked light gasoline separated from catalytic cracking products), was fed into the fluidized bed reactor. The feedstock, after preheating, was mixed with high-temperature steam and introduced into the bottom of the fluidized bed through the feed nozzle. The recalcitrant butene (from the separation of gaseous products) entered the bottom of the fluidized bed reactor through the feed nozzle from the gas feed line. All reactants reacted on the hot catalyst. After the reaction, steam was introduced for stripping. The reaction oil and gas then entered a multi-stage condensation and separation system for separation, yielding cracked gaseous and liquid products. The yields of both gaseous and liquid products were measured. The gaseous products were further separated to obtain ethylene, propylene, butene, and residual components. After the reaction, the reactor automatically heats up to the regeneration temperature, and oxygen is simultaneously introduced into the reactor to regenerate the spent catalyst through coking. The real-time CO2 concentration of the regenerated flue gas is measured by an infrared analyzer, and the coke yield is calculated based on the integral of the flue gas flow rate. The gaseous products are collected and their composition is analyzed by offline chromatography, while the liquid products are analyzed by simulated distillation chromatography to obtain the mass fractions of cracked gasoline (cracking light gasoline and cracked heavy gasoline), cracked diesel, and cracked heavy oil.

[0137] The reaction conditions and product yields for different units are listed in Tables 2 and 3. As can be seen from Table 3, the ethylene yield in this embodiment reached 12.88% by weight, the propylene yield reached 26.17% by weight, the high value-added product yield reached 68.47% by weight, and the coke yield was 9.15% by weight.

[0138] Example 2

[0139] like Figure 1 As shown in Table 1, Kuwaiti crude oil was separated into light distillate, middle distillate, and heavy distillate by true boiling point distillation. The cutoff point between the light distillate and the middle distillate was 200℃, and the cutoff point between the middle distillate and the heavy distillate was 300℃.

[0140] The middle distillate oil is extracted and separated in the first separation unit using an ionic liquid as the solvent. The cation is a dialkyl-substituted imidazole cation, the alkyl groups are methyl and hexyl, and the anion is a hexafluorophosphate anion to obtain a first saturated fraction and a first unsaturated fraction. The yield of the first saturated fraction is 83%, the mass fraction of saturated hydrocarbons in the first saturated fraction is 87.4%, and the mass fraction of aromatics in the first unsaturated fraction is 92.4%. It is a high-quality feedstock for producing high-octane gasoline components or aromatic components.

[0141] The first unsaturated fraction is fed into the hydrogenation unit, where it is upgraded and then sent back to the fluidized bed reactor of the catalytic cracking unit for further conversion into high-value products.

[0142] The heavy distillate oil is fed into the second separation unit where propane is used as a solvent. The second saturated fraction and the second unsaturated fraction are obtained by supercritical extraction. The yield of the second saturated fraction is 76.2%, the mass fraction of saturated hydrocarbons in the second saturated fraction is 52.4%, and the heavy metal removal rate is over 96%. The second unsaturated fraction can be used as a raw material for road asphalt.

[0143] Catalytic cracking experiments were conducted using a fluidized bed reactor for saturated fractions with different distillation ranges. Before the experiment, the catalyst was loaded into the reactor and kept in a fluidized state while the reactor was heated to the reaction temperature. Catalytic cracking feedstock, including light distillate oil, first saturated fraction, second saturated fraction, first unsaturated fraction after hydrotreating, and recalcitrant light gasoline (obtained from cracked light gasoline separated from catalytic cracking products), was fed into the fluidized bed reactor. The feedstock, after preheating, was mixed with high-temperature steam and introduced into the bottom of the fluidized bed through a feed nozzle. The recalcitrant butene (from the separation of gaseous products) entered the bottom of the fluidized bed reactor through a gas feed line via a feed nozzle. All reactants reacted on the hot catalyst. After the reaction, steam was introduced for stripping. The reaction oil and gas then entered a multi-stage condensation and separation system for separation, yielding cracked gaseous and liquid products. The yields of both gaseous and liquid products were measured. The gaseous products were further separated to obtain ethylene, propylene, butene, and residual components. After the reaction, the reactor automatically heats up to the regeneration temperature, and oxygen is simultaneously introduced into the reactor to regenerate the spent catalyst through coking. The real-time CO2 concentration of the regenerated flue gas is measured by an infrared analyzer, and the coke yield is calculated based on the integral of the flue gas flow rate. The gaseous products are collected and their composition is analyzed by offline chromatography, while the liquid products are analyzed by simulated distillation chromatography to obtain the mass fractions of cracked gasoline (cracking light gasoline and cracked heavy gasoline), cracked diesel, and cracked heavy oil.

[0144] The reaction conditions and product yields for different units are listed in Tables 2 and 3. As can be seen from Table 3, the ethylene yield in this embodiment reached 12.93 wt%, the propylene yield reached 26.35 wt%, the high value-added product yield reached 67.93 wt%, and the coke yield was 9.21 wt%.

[0145] Comparative Example 1

[0146] This comparative example is a direct catalytic cracking experiment of crude oil. Kuwaiti crude oil and DMMC-2 catalyst, as shown in Table 1, were used in a fixed fluidized bed reactor. Before the experiment, the catalyst was loaded into the reactor, and the reactor was heated to the reaction temperature while maintaining the catalyst in a fluidized state. The preheated crude oil was mixed with high-temperature steam and fed into the bottom of the fluidized bed through the feed nozzle, where it reacted on the hot catalyst. After the reaction, steam was introduced for stripping, and the reaction oil and gas entered a multi-stage condensation and separation system for separation, yielding cracked gaseous and liquid products. The yields of both gaseous and liquid products were measured. After the reaction, the reactor was automatically heated to the regeneration temperature, and oxygen was simultaneously introduced into the reactor for coke regeneration of the spent catalyst. The real-time CO2 concentration of the regenerated flue gas was measured using an infrared analyzer, and the coke yield was calculated based on the integral of the flue gas flow rate. The gaseous products were collected and their composition was analyzed using offline chromatography, while the liquid products were analyzed using simulated distillation chromatography to obtain the mass fractions of cracked gasoline, cracked diesel, and cracked heavy oil. The reaction conditions and product distribution are listed in Tables 2 and 3.

[0147] As can be seen from the results in Table 3, the yield of ethylene in this comparative example is only 5.56 wt%, the yield of propylene is only 15.85 wt%, the yield of high value-added products is 39.04 wt%, and the yield of coke is 13.12 wt%.

[0148] Comparative Example 2

[0149] Kuwaiti crude oil was separated into light distillate, middle distillate, and heavy distillate by true boiling point distillation. The cutoff point between the light distillate and the middle distillate was 200°C, and the cutoff point between the middle distillate and the heavy distillate was 300°C.

[0150] Catalytic cracking experiments of crude oil fractions with different distillation ranges were conducted using a fluidized bed reactor. Before the experiment, the catalyst was loaded into the reactor and heated to the reaction temperature while maintaining the catalyst in a fluidized state. Crude oil fractions with different distillation ranges were mixed with high-temperature steam in the order of light distillate, middle distillate, and heavy distillate, and after preheating, the mixture was introduced into the bottom of the fluidized bed through the feed nozzle, where it reacted on the hot catalyst. After the reaction, steam was introduced for stripping, and the reaction oil and gas were separated in a multi-stage condensation and separation system to obtain cracked gaseous and liquid products. The yields of both gaseous and liquid products were measured. After the reaction, the reactor was automatically heated to the regeneration temperature, and oxygen was introduced into the reactor to regenerate the catalyst. The real-time CO2 concentration of the regenerated flue gas was measured by an infrared analyzer, and the coke yield was calculated based on the flue gas flow rate integral. The gaseous products were collected and analyzed for compositional distribution using offline chromatography, while the liquid products were analyzed using simulated distillation chromatography to obtain the mass fractions of cracked gasoline, cracked diesel, and cracked heavy oil. The reaction conditions and product distribution are listed in Tables 2 and 3.

[0151] As can be seen from the results in Table 3, the yield of ethylene in this comparative example is only 7.61% by weight, the yield of propylene is only 17.30% by weight, the yield of high value-added products is 43.76%, and the yield of coke is 11.26% by weight.

[0152] Table 2 Reaction conditions for the examples and comparative examples

[0153]

[0154]

[0155] In Table 2, the water vapor usage (by weight%) indicates the proportion of water vapor in the total weight of the catalytic cracking feedstock.

[0156] Catalytic cracking feedstock, expressed as a percentage by weight, represents the total catalytic cracking feedstock after deducting difficult-to-convert components (butene and cracked light gasoline). The weight percentage of difficult-to-convert components or the first unsaturated hydrotreated component in the catalytic cracking feedstock does not include difficult-to-convert components (butene and cracked light gasoline).

[0157] Table 3 Comparison of reaction results between the examples and comparative examples

[0158]

[0159] In Example 2, based on the weight of crude oil, the yield of the first unsaturated fraction is 1.77 wt%. After being hydrogenated by the hydrogenation unit, this fraction is sent to the catalytic cracking unit to undergo a cracking reaction to convert into high-value-added products. Therefore, the yield of high-value-added products in Example 2 is not included in the weight of the first unsaturated fraction.

[0160] As can be seen from the results of the above embodiments and comparative examples, when crude oil catalytic cracking reaction is carried out using the process method and system of this application, the yields of ethylene and propylene are significantly improved, the yield of high value-added products is high, that is, the crude oil atom utilization rate is high.

[0161] In the description of this application, it should be noted that the terms "upper", "lower", "inner", "outer", "front", "rear", "left", "right", etc., indicate the orientation or positional relationship based on the orientation or positional relationship in the working state of this application. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0162] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0163] The present application has been described above with reference to preferred embodiments; however, these embodiments are merely exemplary and illustrative. Various substitutions and modifications can be made to the present application based on these embodiments, all of which fall within the protection scope of the present application.

Claims

1. A process for selective separation-catalytic cracking of crude oil, characterized in that, The process includes the following steps: (1) Distilling crude oil to obtain light oil, intermediate oil and heavy oil; wherein the cutting point of the light oil and the intermediate oil is 160-220℃, and the cutting point of the intermediate oil and the heavy oil is 260-320℃. (2) The intermediate oil is subjected to a first separation to obtain a first saturated fraction and a first unsaturated fraction; (3) The heavy oil is subjected to a second separation to obtain a second saturated fraction and a second unsaturated fraction; (4) The catalytic cracking feedstock is brought into contact with the catalyst to carry out the catalytic cracking reaction, and the cracked gas, cracked light gasoline, cracked heavy gasoline, cracked diesel and cracked heavy oil are obtained by oil-gas separation; The catalytic cracking feedstock comprises the light oil, the first saturated fraction, the second saturated fraction, and a difficult-to-convert component, wherein the difficult-to-convert component includes light hydrocarbons and / or light distillate oil. The crude oil is selected from one or more of the following: paraffin-based, paraffin-intermediate-based, intermediate-paraffin oil, intermediate-based crude oil, and intermediate-naphthenic crude oil. The first separation in step (2) includes: contacting the intermediate oil with an ionic liquid to perform a first extraction separation, wherein the thermal stability of the ionic liquid is higher than 250°C; The second separation in step (3) includes: contacting the heavy oil with a second solvent for supercritical extraction separation, wherein the second solvent is selected from one or a mixture of several of ethane, propane, propylene, n-butane, isobutane, n-pentane, isopentane, hexane, heptane and octane.

2. The process method according to claim 1, characterized in that, The crude oil meets at least one of the following criteria: The density at 20℃ is 800-935 kg / m³. 3 API content less than 30, UOP K value not greater than 12.0, and metal content greater than 30 mg / kg.

3. The process method according to claim 1, characterized in that, The ionic liquid comprises cations and anions; the cations are selected from alkyl-substituted imidazoles and / or pyridines; the anions are selected from at least one of hexafluorophosphate, tetrafluoroborate, and bis(trifluoromethanesulfonyl)imide. The conditions for the first extraction and separation include: a temperature of 15-120℃, a pressure of 0.1-0.5 MPa, and a weight ratio of the ionic liquid to the intermediate oil of (1-15):

1.

4. The process method according to claim 1, characterized in that, The conditions for supercritical extraction separation include: a temperature of 50-100℃, a pressure of 6-20 MPa, and a weight ratio of the second solvent to the heavy oil of (2-5):

1.

5. The process method according to claim 1, characterized in that, The process method further includes the following steps: This allows the first unsaturated fraction from step (2) to be used as a feedstock for the production of high-octane gasoline and / or aromatics; and / or, This allows the second unsaturated fraction from step (3) to be used as a raw material for the production of needle coke and / or road asphalt; and / or, This allows the pyrolysis gas from step (4) to be separated to obtain ethylene, propylene, butene and the remaining components.

6. The process method according to claim 5, characterized in that, The light hydrocarbons of the recalcitrant components include gaseous hydrocarbon products rich in C4 fractions; and / or The light distillate oils containing the difficult-to-convert components include self-produced light distillate oils with a final boiling point of less than 280-360°C.

7. The process method according to claim 6, characterized in that, The process method further includes the following steps: This causes the first unsaturated fraction from step (2) to undergo a hydrogenation reaction, resulting in a hydrogenated first unsaturated fraction; The catalytic cracking feedstock in step (4) also includes the first unsaturated hydrogenation fraction; The first unsaturated hydrogenated fraction accounts for 0.1-10% of the weight of the catalytic cracking feedstock.

8. The process method according to claim 1, characterized in that, The conditions for the catalytic cracking reaction described in step (4) include: The catalytic cracking feedstock is mixed with steam and then fed into the reactor. The reaction temperature is 510-650℃, the reaction time is 1-20 seconds, the weight ratio of the catalyst to the catalytic cracking feedstock is (3-50):1, and the weight ratio of the steam to the catalytic cracking feedstock is (0.03-0.8):1; and / or, The catalyst comprises the following components, based on a dry weight basis: 1-50% zeolite, 5-99% inorganic oxides, and 0-70% clay.

9. The process method according to claim 5, characterized in that, The light hydrocarbons of the difficult-to-convert components include butene obtained by separating the pyrolysis gas; The light distillate oil containing the difficult-to-convert components includes 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; and / or The light distillate oil of the difficult-to-convert components includes the cracked light gasoline obtained from step (4); The weight percentages of butene and cracked light gasoline, which are the difficult-to-convert components, in the catalytic cracking feedstock are each 5-20%.

10. The process method according to claim 1, characterized in that, The catalyst comprises the following components, based on a dry weight basis: 5-45% zeolite, 10-80% inorganic oxides, and 5-60% clay.

11. The process method according to claim 1, characterized in that, The catalyst comprises the following components, based on a dry weight basis: 10-40 wt% zeolite, 20-70 wt% inorganic oxides, and 10-50 wt% clay.

12. A system for selective separation-catalytic cracking of crude oil, characterized in that, The system includes a distillation unit (100), a first separation unit (202), a second separation unit (203), and a catalytic cracking reaction unit (400). The distillation unit (100) is provided with a crude oil inlet (101), a light distillate oil outlet (201a), a middle distillate oil outlet (202a) and a heavy distillate oil outlet (203a). The middle distillate oil outlet (202a) of the distillation unit (100) is connected to the material inlet of the first separation unit (202). The first separation unit (202) is also provided with a first saturated outlet (202b) and a first unsaturated outlet (202c). The heavy distillate oil outlet (203a) of the distillation unit (100) is connected to the material inlet of the second separation unit (203). The second separation unit (203) is also provided with a second saturated outlet (203b) and a second unsaturated outlet (203c). The light distillate oil outlet (201a), the first saturated fraction outlet (202b), and the second saturated fraction outlet (203b) are respectively connected to the catalytic cracking feedstock inlet of the catalytic cracking reaction unit (400); the catalytic cracking reaction unit (400) is also provided with a cracked gas outlet (401), a cracked light gasoline outlet (402), a cracked heavy gasoline outlet (403), a cracked diesel outlet (404), and a cracked heavy oil outlet (405). The first separation unit (202) is an extraction separation unit, and the second separation unit (203) is a supercritical extraction separation unit.

13. The system according to claim 12, characterized in that, The system also includes a high-octane gasoline production unit and / or an aromatics production unit, wherein the first unsaturated outlet (202c) is connected to the feed inlet of the high-octane gasoline production unit and / or the feed inlet of the aromatics production unit; and / or, The system also includes a needle coke production unit and / or a road asphalt production unit, wherein the second unsaturated outlet (203c) is connected to the raw material inlet of the needle coke production unit and / or the raw material inlet of the road asphalt production unit; and / or, The system also includes a gas separation unit. The pyrolysis gas outlet (401) of the catalytic cracking reaction unit (400) is connected to the gas inlet to be separated of the gas separation unit. The gas separation unit is also provided with an ethylene outlet, a propylene outlet, a butene outlet and a residual component outlet.

14. The system according to claim 13, characterized in that, The catalytic cracking reaction unit (400) is further provided with a difficult-to-convert component inlet (406), which is connected to the cracked light gasoline outlet (402) and / or the butene outlet of the gas separation unit; and / or, The system is also provided with a hydrogenation reaction unit (300), the first unsaturated outlet (202c) is connected to the hydrogenation feedstock inlet of the hydrogenation reaction unit (300), and the hydrogenation product outlet (301) of the hydrogenation reaction unit (300) is connected to the catalytic cracking feedstock inlet of the catalytic cracking reaction unit (400).

15. The system according to claim 12, characterized in that, The catalytic cracking reaction unit (400) is selected from one or a combination of several reactors, including fluidized bed, turbulent bed, fast bed and dilute phase transport bed; the reactor is selected from one or a combination of two of the following reactors in series: constant linear velocity reactor, constant diameter reactor, variable diameter reactor, upward transport line reactor and downward transport line reactor.

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