Crude oil selective separation-catalytic cracking process method and system

Abstract

The invention relates to a process method and system for selective separation-catalytic cracking of crude oil, and the process method comprises the following steps: (1) carrying out distillation cutting on the crude oil to obtain light oil, intermediate oil and heavy oil; (2) carrying out first separation on the intermediate oil to obtain a first saturated component and a first unsaturated component; (3) carrying out second separation on the heavy oil to obtain a second saturated component and a second unsaturated component; (4) contacting the catalytic cracking raw material with a catalyst to carry out catalytic cracking reaction, and carrying out oil-gas separation to obtain cracked gas, cracked light gasoline, cracked heavy gasoline, cracked diesel oil and cracked heavy oil; the catalytic cracking raw material comprises light oil, a first saturated component, a second saturated component and an optional difficult-to-convert component, and the difficult-to-convert component comprises light hydrocarbon and / or light distillate oil. According to the method, the crude oil is selectively separated after being distilled and cut, and specific catalytic cracking raw materials are selected for catalytic cracking reaction, so that the inferior crude oil is better converted into high-value products such as low-carbon olefins and light aromatic hydrocarbons.

Description

Technical Field

[0001] The invention relates to the technical field of petrochemical industry, and in particular to a process method and system for selective separation-catalytic cracking of crude oil. Background Art

[0002] Refining capacity is in excess, and the demand for refined oil products is slowing down. Ethylene, propylene and BTX (benzene-toluene-xylene) are key basic organic synthetic raw materials with huge demand, while the demand for chemical products continues to be strong. The existing technical route for producing propylene and BTX from petroleum is developed on the basis of the traditional petroleum refining process that mainly produces oil products. There are problems such as long production process, low chemical yield and insignificant economic benefits. The technical measures to solve this problem are to develop key core technologies that mainly produce chemicals and can direct the 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 subverted the traditional refining process and promoted the integration of refining and chemical to a new level of direct production of chemicals from crude oil.

[0003] ExxonMobil Corporation of the United States is a pioneer in the research and development of crude oil steam cracking to produce olefins. It is the first company to build an industrial demonstration unit and has applied for a series of patents, such as CN200580016314.X. The process method of the company's crude oil direct chemicals is that the crude oil directly enters the steam cracking furnace, and the light components and recombinant components are separated by flash evaporation. The light components (gaseous components) enter the steam cracking furnace for cracking, and the recombinant components (liquid components) are used as refinery raw materials. If the selected crude oil is light enough, there is no fraction above 593°C, that is, no bottom residue oil, and it does not need to rely on a refinery. The company's first industrial unit uses ultra-light paraffin-based tapis crude oil with an API gravity of 42.7 as raw material.

[0004] The technical characteristics of Saudi Aramco National Oil Company are that it adopts crude oil pretreatment technology and hydroprocessing technology to minimize the impact of non-volatile components in crude oil on steam cracking. At the same time, a vapor-liquid (steam and liquid) separation device is installed between the convection section and the radiation section of the steam cracking furnace to remove non-volatile liquid (liquid phase), ensuring that the material entering the radiation section does not carry liquid, thereby ensuring that the furnace tube does not coke, and the heavy components enter the catalytic cracking unit. It can be said that it is a process for producing olefins and aromatics from crude oil that integrates hydroprocessing, steam cracking and catalytic cracking processes.

[0005] Due to the presence of heavy components in crude oil that are difficult to vaporize, the existing crude oil direct chemical technology is only suitable for low-sulfur paraffin-based crude oil with an API degree of about 45. Other crude oil chemical technologies are different according to the different processing processes of heavy components in crude oil. The crude oil chemical technology routes of major companies are different, but they all use fraction cutting and combine process technologies according to the properties of distillate oils with different distillation ranges to achieve crude oil production chemicals. Compared with the traditional refining process, only the distillation range and quantity of the cut distillate oils are changed, and then the existing processing technology is integrated, which fails to achieve fundamental technological changes. In addition, these existing combined technologies are more suitable for light crude oil or paraffin-based crude oil. When using inferior crude oil such as heavy crude oil or intermediate-based crude oil as raw materials, the yield of chemicals such as high value-added products 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 needs to be solved urgently. Summary of the invention

[0007] The present invention provides a process method and system for selective separation and catalytic cracking of crude oil, the purpose of which is to selectively separate crude oil and then select specific catalytic cracking raw materials for catalytic cracking reaction, so as to better convert low-quality 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) subjecting crude oil to distillation and cutting to obtain light oil, intermediate oil and heavy oil; wherein the cutting point between the light oil and the intermediate oil is 160-220° C., and the cutting point between the intermediate oil and the heavy oil is 260-320° C.;

[0010] (2) subjecting the intermediate oil to a first separation to obtain a first saturated fraction and a first unsaturated fraction;

[0011] (3) subjecting the heavy oil to a second separation to obtain a second saturated fraction and a second unsaturated fraction;

[0012] (4) contacting the catalytic cracking feedstock with the catalyst to carry out a catalytic cracking reaction, and obtaining cracking gas, cracking light gasoline, cracking heavy gasoline, cracking diesel and cracking heavy oil through oil and gas separation;

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

[0014] In a second aspect, the present invention relates to a system for selective separation and 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 provided 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 inlet of the material to be separated of the first separation unit, and the first separation unit is also provided with a first saturated fraction outlet and a first unsaturated fraction outlet;

[0017] The heavy fraction oil outlet of the distillation unit is connected to the inlet of the material to be separated of the second separation unit, and 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 fraction outlet and the second saturated fraction 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 cracking gas outlet, a cracking light gasoline outlet, a cracking heavy gasoline outlet, a cracking diesel outlet and a cracking heavy oil outlet.

[0019] Beneficial effects:

[0020] 1) The crude oil has strong adaptability. The process method of combining crude oil component separation and catalytic cracking units can convert the intermediate base crude oil with poor quality into high value-added products;

[0021] 2) High crude oil utilization rate. Since the size and structure of aromatics in the distillates of inferior crude oil are quite different, the components composed of different hydrocarbons can be selectively separated according to the properties of the distillates of crude oil. Targeted and selective catalytic conversion can be carried out according to the characteristics of the components, which can improve the selectivity of the process and achieve efficient utilization of crude oil.

[0022] 3) The yield of high value-added products is high. The unsaturated fraction rich in aromatics in the middle distillate oil can be directly used as the production of aromatic components or high-octane gasoline blending components. The unsaturated fraction rich in polycyclic aromatics or asphaltene in the heavy distillate oil can be used as needle coke or road asphalt raw materials according to different properties; the saturated fraction is converted into light olefins and aromatics as a catalytic cracking raw material. The yield of high value-added products in the whole process is more than 65%;

[0023] 4) The online rate of the device is high. Inferior crude oil has high residual carbon, high metal and high asphaltene content. After component separation, the quality of the catalytic cracking raw material is greatly improved. Not only is the yield of the target product high, but the operation cycle is also extended and the online rate is increased, thereby effectively improving the economic benefits.

[0024] By adopting the process method or system of crude oil selective separation-catalytic cracking of the present application, low-carbon olefins and light aromatics can be efficiently produced from inferior crude oil, which can not only produce high-value chemical raw materials and promote the deep integration of oil refining and petrochemical industries, but also effectively respond to the challenges brought about by the shortage of oil resources; not only does it have good crude oil adaptability and high chemical yield, but it also produces other high-value-added chemical raw materials as by-products, and the crude oil utilization rate is high. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0026] Description of Reference Numerals

[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 fraction outlet

[0029] 202c first unsaturated fraction outlet 203 second separation unit 203a heavy fraction 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 Cracking light gasoline export 403 Cracking heavy gasoline export 404 Cracking diesel export

[0033] 405 Cracking heavy oil outlet 406 Difficult-to-convert component inlet DETAILED DESCRIPTION

[0034] The present application is further described in detail below through the accompanying drawings and embodiments. Through these descriptions, the characteristics and advantages of the present application will become clearer and more specific.

[0035] The word "exemplary" is used exclusively herein to mean "serving as an example, embodiment, or illustration." Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments. Although various aspects of the embodiments are shown in the drawings, the drawings are not necessarily drawn to scale unless otherwise noted.

[0036] In addition, the technical features involved in different embodiments of the present 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) subjecting crude oil to distillation and cutting to obtain light oil, intermediate oil and heavy oil; wherein the cutting point between the light oil and the intermediate oil is 160-220° C., and the cutting point between the intermediate oil and the heavy oil is 260-320° C.;

[0039] (2) subjecting the intermediate oil to a first separation to obtain a first saturated fraction and a first unsaturated fraction;

[0040] (3) subjecting the heavy oil to a second separation to obtain a second saturated fraction and a second unsaturated fraction;

[0041] (4) contacting the catalytic cracking feedstock with the catalyst to carry out a catalytic cracking reaction, and obtaining cracking gas, cracking light gasoline, cracking heavy gasoline, cracking diesel and cracking heavy oil through oil and gas separation;

[0042] The catalytic cracking feedstock comprises the light oil, the first saturated fraction, the second saturated fraction and optional difficult-to-convert components, and the difficult-to-convert components include 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 means the temperature of heating during distillation separation. The cutting points of light oil and intermediate oil can be specifically 170°C, 175°C, 180°C, 185°C, 190°C, 195°C, 200°C, 205°C, 210°C, 215°C, etc., and the cutting points of intermediate oil and heavy oil can be specifically 265°C, 270°C, 275°C, 280°C, 285°C, 290°C, 300°C, 305°C, 310°C, 315°C, etc.

[0044] It should be noted that in the process method of the present 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, the cutting is performed according to the above-mentioned cutting points to obtain light oil, intermediate oil and heavy oil; in steps (2) and (3), the intermediate oil and heavy oil are respectively separated into components to obtain saturated fractions and unsaturated fractions, respectively, the saturated fraction obtained is rich in saturated hydrocarbons, the unsaturated fraction obtained is rich in aromatic hydrocarbons, and 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 paraffin and cycloparaffin obtained from steps (2) and (3) are used as catalytic cracking raw materials, and a catalytic cracking reaction occurs under the catalytic action of high temperature and catalyst, and the reaction products can be separated to better obtain high-value products such as low-carbon olefins and light aromatic hydrocarbons.

[0045] It should be noted that the optional difficult-to-convert component means that the catalytic cracking feedstock may not contain the difficult-to-convert component, or may contain any proportion of the difficult-to-convert component. The light hydrocarbons and / or light distillate oil of the difficult-to-convert component may be obtained from the process of the present application or introduced from the outside. Light distillate oil, middle distillate oil and heavy distillate oil may be referred to as light oil, middle oil and heavy oil, respectively.

[0046] The present invention firstly distills and separates crude oil according to the above-mentioned cutting point to obtain light oil, intermediate oil and heavy oil; then separates the intermediate oil and heavy oil to obtain saturated fraction and unsaturated fraction respectively, and the obtained two saturated fractions and the light oil are used as catalytic cracking raw materials for catalytic cracking reaction.

[0047] After years of research and development experiments, the inventors of this application have found that the crude oil is first distilled and separated, and then the materials in some distillation ranges are selectively separated, so that the saturated fraction obtained by the selective separation and the light oil are used as raw materials for catalytic cracking reaction. The process is ingenious and scientific, which can better transform the crude oil into high-value products such as light olefins and light aromatics, and significantly improve the yield of high value-added products. The yield of high value-added products in this application refers to the total yield of light 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), cracking gas, cracking light gasoline, cracking heavy gasoline, cracking diesel and cracking heavy oil are obtained through steps such as oil agent separation and oil-gas separation. The gas product, i.e., cracking gas, can be separated to obtain ethylene, propylene, butene, etc., and the cracking heavy gasoline in the liquid product can be separated to obtain light aromatic hydrocarbons BTX, etc. The separation process involved can adopt conventional separation methods in the art, 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 mixed crude oils selected from paraffin-based, paraffin-intermediate-based crude oil, intermediate-paraffinic crude oil, intermediate-based crude oil and intermediate-cycloalkyl crude oil; and / or

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

[0051] Density at 20°C is 800-935 kg / m 3 , API gravity is less than 30, UOP K value is not greater than 12.0, and metal content is 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 of intermediate base attribute, and the second key component is of paraffinic base attribute; paraffin-intermediate base crude oil can have two key components, the first key component is of paraffinic base attribute, and the second key component is of intermediate base attribute; any of the first key component and the second key component of intermediate base crude oil belongs to intermediate base attribute. The process method of the present application can distill and cut these inferior oils, selectively separate them, catalytically crack the saturated fractions and light oils, and then produce high-value products such as low-carbon olefins and light aromatics with high yields.

[0053] It should be noted that the inventors of the present application have developed the process method for selective separation of crude oil-catalytic cracking of the present application after many years of research and development. The process method of the present application has strong adaptability to raw materials and high yield of high value-added products. Even inferior crude oil can well produce the above-mentioned high-value products, and can achieve efficient utilization of inferior crude oil resources. Therefore, the process method of the present application can be called the process method for selective separation of inferior crude oil-catalytic cracking.

[0054] According to another specific embodiment of the process method of the first aspect of the present invention, the first separation in step (2) comprises: 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°C;

[0056] Wherein, 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(trifluoromethylsulfonyl)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 separation include: a temperature of 15-120° C., a pressure of 0.1-0.5 MPa, and a weight ratio of the ionic liquid to the intermediate oil, or a weight ratio of the first solvent to the intermediate oil, each independently being (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 by the first separation can be 75-90% by weight. The above-mentioned first solvent or ionic liquid is selected, and the first extraction separation is performed under the above-mentioned conditions, so that the first separation process can be better performed, and the obtained first saturated fraction, the second saturated fraction and the light oil are used as catalytic cracking raw materials for catalytic cracking reaction, which is conducive to further improving the yield of catalytic cracking high value-added products with low energy consumption.

[0060] According to a specific embodiment of the process method of the first aspect of the present invention, the second separation in step (3) comprises: 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 ethane, propane, propylene, n-butane, isobutane, n-pentane, isopentane, hexane, heptane and octane;

[0062] The conditions for the supercritical extraction separation include: a temperature of 50-100° C., 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 by the second separation, the content of saturated hydrocarbons in the second saturated fraction may be greater than 45% by weight. The above-mentioned second solvent is selected, and supercritical extraction separation is performed under the above-mentioned conditions. The obtained second saturated fraction, the first saturated fraction and the light oil are used as catalytic cracking raw materials for the catalytic cracking reaction of step (4), and the above-mentioned high value-added product can be obtained with a higher yield.

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

[0065] The first unsaturated fraction from step (2) is used as a raw material for producing high-octane gasoline and / or aromatics; and / or,

[0066] Using the second unsaturated fraction from step (3) as a raw material for producing needle coke and / or road asphalt; and / or,

[0067] The cracked gas from step (4) is separated to obtain ethylene, propylene, butene and remaining components.

[0068] It should be noted that the separation method of the cracked gas obtained in step (4) to obtain ethylene, propylene, butene and the remaining components can adopt conventional separation methods in the art, or methods well known to those skilled in the art, and the present invention is not limited thereto.

[0069] The process method obtained by the inventors of the present application after many years of research and development experiments, through distillation cutting and selective separation, not only can the light oil, the first saturated fraction and the second saturated fraction be used as raw materials to obtain high-value products with significantly improved yields through catalytic cracking reaction, but the obtained first unsaturated fraction and the second unsaturated fraction can also be used as raw materials for producing high-octane gasoline and / or aromatics, raw materials for producing needle coke and / or road asphalt. The saturated and unsaturated fractions in crude oil can be well converted or utilized, and the utilization rate of crude oil is significantly improved.

[0070] According to another specific embodiment of the process method described in the first aspect of the present invention, the light hydrocarbons of the difficult-to-convert components include a gaseous hydrocarbon product rich in a C4 fraction, preferably including butenes obtained by separating the cracked gas;

[0071] The light distillate oil of the difficult-to-convert components includes self-produced light distillate oil with a final boiling point of less than 280-360°C and one or more of the following fractions: straight-run naphtha, straight-run kerosene, straight-run diesel produced by other primary processing units, topped oil, raffinate oil, hydrocracking light naphtha, pentane oil, coker gasoline, Fischer-Tropsch synthetic oil, catalytic cracking light gasoline, hydrogenated gasoline and hydrogenated diesel produced by other secondary processing units;

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

[0073] The weight proportion of butene and cracked light gasoline as the difficult-to-convert components in the catalytic cracking feedstock is independently 5-20%.

[0074] It should be noted that, in this preferred embodiment, the catalytic cracking raw material in step (4) includes not only light oil, the first saturated fraction, and the second saturated fraction, but also difficult-to-convert components, and the difficult-to-convert components may include butene obtained by separation of cracked gas and / or the cracked light gasoline obtained by oil-gas separation. After years of research and development experiments, the inventors of the present application found that using the difficult-to-convert components together with the above two saturated components and light oil as catalytic cracking raw materials for the catalytic cracking reaction of step (4) is conducive to better converting the catalytic cracking raw materials into high-value products such as light olefins (ethylene, propylene, butene), light aromatics BTX (benzene, toluene and xylene), and can further improve the yield of high value-added products. In the catalytic cracking raw material, the weight proportion of the difficult-to-convert components can be 8%, 10%, 12% and 15%, etc. The proportion of butene or cracked light gasoline as difficult-to-convert components in the catalytic cracking raw material is based on the amount of the catalytic cracking raw material excluding the difficult-to-convert components.

[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 of the present application and gaseous hydrocarbons rich in C4 fractions produced by other device processes, preferably C4 fractions or butenes produced by the process of the present application. The light distillate oil of the difficult-to-convert components may include light distillate oil with a final boiling point of less than 280-360°C produced by the process of the present application, or a mixed oil of one or more of the above-mentioned straight-run naphtha, straight-run kerosene, etc. introduced by other external processes or devices, such as a mixture of one or more of the straight-run naphtha, straight-run kerosene, and straight-run diesel processed in the first place; a mixed oil of one or more of the secondary processed topped oil, raffinate oil, hydrocracking light naphtha, pentane oil, coker gasoline, Fischer-Tropsch synthetic oil, catalytic cracking light gasoline, hydrogenated gasoline, and hydrogenated diesel.

[0076] It should be noted that, in one embodiment, the light hydrocarbon in the difficult-to-convert component is a C4 component, which refers to a low molecular hydrocarbon compound that exists in the form of gas at room temperature and pressure and has a C4 fraction as the main component, including alkanes, olefins and alkynes with 4 carbon atoms in the molecule. It includes a gaseous hydrocarbon product rich in C4 fraction produced by the process of the present invention, and may also include gaseous hydrocarbons rich in C4 fraction produced by other processes, among which the C4 fraction produced by the process of the present 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 preferably above 70% by weight.

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

[0078] subjecting the first unsaturated fraction from step (2) to a hydrogenation reaction to obtain a hydrogenated first unsaturated fraction;

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

[0080] The weight proportion of the hydrogenated first unsaturated component in the catalytic cracking feedstock is 0.1-10%.

[0081] It should be noted that, as a preferred embodiment, the first unsaturated fraction from step (2) is subjected to a hydrogenation treatment 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 a catalytic cracking raw material for the catalytic cracking reaction of step (4), or the hydrogenated first unsaturated fraction can be used as a raw material for producing a high-octane gasoline component or an aromatic component. In this preferred embodiment, in step (4), the catalytic cracking raw material includes light oil, the first saturated fraction, the second saturated fraction, butene obtained by separation of gas products, cracked light gasoline obtained by separation of oil and gas, and the hydrogenated first unsaturated fraction obtained by hydrogenation reaction of the first unsaturated fraction obtained from step (2). The catalytic cracking raw material composed of the above composition can better prepare high-value products through catalytic cracking reaction, thereby further improving the yield of high-value products. The weight proportion of the hydrogenated first unsaturated fraction in the catalytic cracking raw material 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 in step (2) include a hydrogen partial pressure of 10.0-25.0 MPa, a reaction temperature of 330-450°C, and a volume space velocity of 0.1-2.0 h -1 , Hydrogen oil volume ratio 1000-2000Nm 3 / m 3 The active metal component in the hydrogenation catalyst is selected from metals of Group VIB and / or non-precious metals of Group VIII, and the carrier is selected from any one or more of alumina, silicon dioxide, and amorphous silicon aluminum. The metal of Group VIB is molybdenum and / or tungsten, and the non-precious metal of Group VIII 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 raw material is mixed with water vapor and then fed, wherein the reaction temperature is 510-650° C., the reaction time is 1-20 seconds, the weight ratio of the catalyst to the catalytic cracking raw material is (3-50):1, and the weight ratio of the water vapor to the catalytic cracking raw material is (0.03-0.8):1; and / or,

[0085] The catalyst comprises the following components, based on the dry weight of the components and the catalyst:

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

[0087] Preferably 5-45 wt% zeolite, 10-80 wt% inorganic oxide, and 5-60 wt% clay;

[0088] More preferably, it is 10-40 wt% of zeolite, 20-70 wt% of inorganic oxide, and 10-50 wt% of clay.

[0089] It should be noted that, in one embodiment, the zeolite includes a medium-pore zeolite and an optional large-pore zeolite, the medium-pore zeolite is selected from ZSM series zeolites, ZRP zeolites, and any combination thereof; the large-pore zeolite is selected from rare earth Y-type zeolite, rare earth hydrogen Y-type zeolite, ultra-stable Y-type zeolite and high silicon Y-type zeolite, and any combination thereof. As an example, the large-pore zeolite can be selected from one or more of rare earth Y (REY) type zeolite, rare earth hydrogen Y (REHY) type zeolite, ultra-stable Y-type zeolite obtained by different methods, and high silicon Y-type zeolite. The medium-pore zeolite can be selected from zeolites with MFI structure, such as ZSM series zeolites and / or ZRP zeolites. Optionally, the above-mentioned medium-pore zeolite can also be modified with non-metallic elements such as phosphorus and / or transition metal elements such as iron, cobalt, and nickel. For a more detailed description of ZRP zeolite, see U.S. Patent No. 5,232,675A. The ZSM series zeolite is preferably selected from a mixture of one or more of ZSM-5, ZSM-11, ZSM-12, ZSM-23, ZSM-35, ZSM-38, ZSM-48 and other zeolites of similar structure. For a more detailed description of ZSM-5, see U.S. Pat. No. 3,702,886A.

[0090] In one embodiment, the medium-pore zeolite accounts for 10-90% by weight of the total weight of the zeolite, preferably 50-80% by weight, on a dry basis. In the present application, the medium-pore zeolite and large-pore zeolite follow the conventional definition in the art, that is, the average pore size of the medium-pore zeolite is about 0.5-0.6 nm, and the average pore size of the large-pore zeolite is about 0.7-1.0 nm. The inorganic oxide is used as a binder, preferably silicon dioxide (SiO2) and / or aluminum oxide (Al2O3). The clay is used as a matrix (i.e., a carrier), preferably kaolin and / or halloysite.

[0091] It should be noted that in the process method of the present application, by controlling the conditions of the catalytic cracking reaction in step (4) as above, the catalytic cracking raw materials can be better reacted under the catalysis of the above-mentioned catalyst to form high-value products such as light olefins (ethylene, propylene, butene), light aromatics BTX (benzene, toluene and xylene), etc., which can further improve the yield of high value-added products.

[0092] In a second aspect, the present invention relates to a system for selective separation and 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 inlet of the material to be separated of the first separation unit 202, and the first separation unit 202 is also provided with a first saturated fraction outlet 202b and a first unsaturated fraction outlet 202c;

[0095] The heavy fraction oil outlet 203a of the distillation unit 100 is connected to the inlet of the material to be separated of the second separation unit 203, and 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 cracking gas outlet 401, a cracking light gasoline outlet 402, a cracking heavy gasoline outlet 403, a cracking diesel outlet 404 and a cracking 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 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 based on but 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 the present application, crude oil enters the distillation unit 100 through the crude oil inlet 101, and is cut into light distillate oil, middle distillate oil and heavy distillate oil through distillation. The three oil products obtained by cutting flow out of the distillation unit 100 through the light distillate oil outlet 201a, the middle distillate oil outlet 202a and the 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 the first saturated fraction and the first unsaturated fraction by the first separation unit 202, and the heavy distillate oil is separated into the second saturated fraction and the second unsaturated fraction by 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 feed inlet, and 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 feed inlet; the light distillate oil and the two saturated fractions are used as catalytic cracking feedstocks in the catalytic cracking reaction unit 400 in contact with the catalyst to undergo a catalytic cracking reaction at high temperature, and are sequentially separated through an oil agent separation device and an oil-gas separation device to obtain cracked gas, cracked light gasoline, cracked heavy gasoline, cracked diesel and cracked heavy oil, and the above-mentioned products flow out through 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, respectively.

[0099] It should be noted that the system of the present application first distills and cuts the crude oil through the distillation unit 100, and the light distillate oil obtained by the distillation and cutting directly enters the catalytic cracking reaction unit 400 without separation. The intermediate distillate oil and the heavy distillate oil obtained by the distillation and cutting are separated in the first separation unit 202 and the second separation unit 203 respectively, and the first saturated fraction and the second saturated fraction obtained by separation enter 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 raw materials for catalytic cracking in the catalytic cracking reaction unit 400, so that the crude oil can be better converted into high-value products such as light olefins (ethylene, propylene, butene), 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, equipment such as an oil agent separation device and a reaction product separation device may also be provided. The oil agent separation device and the reaction product separation device are both well known to those skilled in the art. For example, the oil agent separation device may include a cyclone separator, a settler and a stripper, etc., and the reaction product separation device may be a distillation tower, etc.

[0101] According to a specific embodiment of the system of 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, and the first unsaturated outlet 202c is connected to the raw material inlet of the high-octane gasoline production unit and / or the raw material inlet of the aromatics production unit;

[0102] and / or,

[0103] The system is further provided with a needle coke production unit and / or a road asphalt production unit, and 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 further comprises a gas separation unit, the cracked gas outlet 401 of the catalytic cracking reaction unit 400 is connected to the gas inlet to be separated of the gas separation unit, and the gas separation unit is further provided with an ethylene outlet, a propylene outlet, a butene outlet and an outlet for remaining components.

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

[0106] It should be noted that the cracked gas flowing out through the cracked gas outlet 401 is separated into ethylene, propylene, butene and remaining components by a gas separation unit.

[0107] The system of the present application uses light distillate oil, the first saturated fraction and the second saturated fraction as raw materials for catalytic cracking reaction in the catalytic cracking reaction unit 400, so as to better obtain high-value products. The two unsaturated fractions obtained in the selective separation process can be used as raw materials for producing aromatics, high-octane gasoline, needle coke or road asphalt, so that various components contained in crude oil can be well utilized.

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

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

[0110] It should be noted that, as a variant implementation, the difficult-to-convert component inlet 406 can be connected to the gaseous hydrocarbon outlet of the C4 fraction rich in other external devices, or to the light distillate oil outlet with a final boiling point less than 280-360°C of other external devices, specifically, it can be connected to one or more of the straight-run naphtha outlet, straight-run kerosene outlet, and straight-run diesel outlet of other primary processing devices, or to one or more of the top oil outlet, raffinate oil outlet, hydrocracking light naphtha outlet, pentane oil outlet, coker gasoline outlet, Fischer-Tropsch synthetic oil outlet, catalytic cracking light gasoline outlet, hydrogenated gasoline outlet, and hydrogenated diesel outlet of other secondary processing devices.

[0111] In the present application, the terms "upstream" and "downstream" are based on the flow direction of the reactants. For example, when the reactants flow from bottom to top, "upstream" means the position below, while "downstream" means the position above.

[0112] It should be noted that the difficult-to-convert component inlet 406 may be one, two or more. In one embodiment, when there is one difficult-to-convert component inlet 406, light hydrocarbons and light distillate oil as difficult-to-convert components may enter the catalytic cracking reaction unit through the same difficult-to-convert component inlet 406; in another preferred embodiment, the number of difficult-to-convert component inlets 406 is two or more, and light hydrocarbons and light distillate oil as difficult-to-convert components enter the catalytic cracking reactor through different difficult-to-convert component inlets 406, respectively. Specifically, light hydrocarbons are introduced into the catalytic cracking reactor at one or more difficult-to-convert component inlets 406 upstream of the difficult-to-convert component inlet 406 (introduction position) for introducing light distillate oil, which is conducive to obtaining high-value products with a higher yield.

[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 difficult-to-convert component inlets, and the one or more difficult-to-convert component inlets can be independently arranged at the lower part of the catalytic cracking reactor. Further preferably, the difficult-to-convert component inlets are independently arranged at the middle and upstream 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 at a light distillate oil inlet at one or more locations upstream of the 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, the first unsaturated branch 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] As a preferred embodiment, the middle distillate oil is separated into a first saturated fraction and a first unsaturated fraction by the first separation unit 202, the obtained first unsaturated fraction enters the hydrogenation reaction unit 300, and undergoes a hydrogenation reaction in the presence of hydrogen and a hydrogenation catalyst, and the first unsaturated fraction hydrogenated product flows out through the hydrogenation product outlet 301 and enters the catalytic cracking reaction unit 400 as a catalytic cracking feedstock for catalytic cracking reaction. In this preferred embodiment, the first unsaturated fraction hydrogenated product, light distillate oil, and two saturated fractions (butene obtained by gas separation and cracked light gasoline obtained by oil and gas separation may also be included) are used as catalytic cracking feedstocks for catalytic cracking reaction, 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 reactors selected from fluidized bed, turbulent bed, fast bed and dilute phase transport bed; the reactor is selected from one or a series combination of 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 the present 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 to improve the yield of high-value products of the system.

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

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

[0122] like Figure 1 As shown, crude oil enters the distillation unit 100 through the 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 the light distillate oil outlet 201a and enters the catalytic cracking reaction unit 400;

[0124] The separated middle distillate oil flows out through the middle distillate oil outlet 202a and enters the first separation unit 202, contacts with the extraction solvent and separates the components 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 a high-octane gasoline component or an aromatic component. Optionally, the first unsaturated fraction flows out through the first unsaturated fraction outlet 202c and is sent to the hydrogenation reaction unit 300, where it is hydrogenated under the action of hydrogen and a hydrogenation catalyst. The 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 the heavy distillate oil outlet 203a and enters the second separation unit 203, contacts with the extraction solvent and separates the components 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 and is used 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, the light distillate oil from the light distillate oil outlet 201a of the distillation unit, and optionally the difficult-to-convert components from the difficult-to-convert components inlet 406 enter the catalytic cracking reaction unit 400, and a catalytic cracking reaction occurs under the action of heat and a catalytic cracking catalyst. The reaction products are separated to obtain cracking gas (flowing out of the cracking gas outlet 401), cracking light gasoline (flowing out of the cracking light gasoline outlet 402), cracking heavy gasoline (flowing out of the cracking heavy gasoline outlet 403), cracking diesel (flowing out of the cracking diesel outlet 404) and cracking heavy oil (flowing out of the cracking heavy oil outlet 405). The cracking gas can be further separated to obtain ethylene, propylene, butene and other products.

[0127] The present invention is further described in detail by way of examples below, but the present invention is not limited thereto. In the following examples, unless otherwise specified, the experimental instruments and raw materials involved are all commercially available products.

[0128] The feedstock oil used in the following examples and comparative examples is Kuwait crude oil, and its properties are shown in Table 1. The catalyst used in the catalytic cracking unit is a commercial catalytic cracking catalyst purchased from the Catalyst Branch of Sinopec, with a trade name of DMMC-2. The trade name of the hydrotreating catalyst is RN-32L.

[0129] Table 1 Properties of crude oil used

[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 Carbon residue value / 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 light olefins (ethylene, propylene, butene), light aromatics BTX (benzene, toluene and xylene), the production of aromatics or high-octane gasoline components (first unsaturated fractions), and the production of needle coke or road asphalt components (second unsaturated fractions). The yield of a certain product can refer to the weight percentage of the product in crude oil.

[0132] Example 1

[0133] like Figure 1 As shown, the Kuwait crude oil in Table 1 is subjected to actual boiling point distillation to separate light distillate oil, middle distillate oil and heavy distillate oil, wherein the cut point between the light distillate oil and the middle distillate oil is 200°C, and the cut point between the middle distillate oil and the heavy distillate oil is 300°C.

[0134] The middle distillate oil is extracted and separated in the first separation unit by using ionic liquid as solvent, the cation is dialkyl substituted imidazolium cation, the alkyl groups are methyl and hexyl respectively, and the anion is hexafluorophosphate anion to obtain the first saturated fraction and the first unsaturated fraction, wherein 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 aromatic hydrocarbons in the first unsaturated fraction is 92.4%, which is a high-quality raw material for producing high-octane gasoline components or aromatic components.

[0135] The heavy distillate oil is sent to the second separation unit using propane as the solvent, and is separated by supercritical extraction to obtain the second saturated fraction and the second unsaturated fraction, wherein the yield of the second saturated fraction is 76.2%, the mass fraction of saturated hydrocarbons in the second saturated fraction is 52.4%, the heavy metal removal rate is above 96%, and the second unsaturated fraction can be used as a raw material for road asphalt.

[0136] A fluidized bed reactor device is used to conduct a catalytic cracking reaction test of saturated fractions of different distillation ranges. Before the test, the catalyst is first loaded into the reactor, and the reactor is heated to the reaction temperature while the catalyst is kept in a fluidized state. The catalytic cracking raw materials including light distillate oil, the first saturated fraction, the second saturated fraction and the difficult-to-convert component light gasoline (the cracked light gasoline obtained by separation of catalytic cracking products) are allowed to enter the fluidized bed reactor device. The raw materials are mixed with high-temperature water vapor after preheating and enter the bottom of the fluidized reaction bed through the feed nozzle. The difficult-to-convert component butene (from the separation of gas products) enters the bottom of the fluidized bed reactor from the gas feed pipeline through the feed nozzle. All reaction raw materials react on the hot catalyst. After the reaction, water vapor is introduced for stripping, and the reaction oil and gas enter the multi-stage condensation separation system for separation to obtain cracking gas products and liquid products. The yields of the gas products and liquid products are measured. The gas products are separated to obtain ethylene, propylene, butene and remaining components. After the reaction is completed, the reactor is automatically heated to the regeneration temperature, and oxygen is introduced into the reactor to regenerate the catalyst. 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 flue gas flow integral. The gas products are collected and distributed by offline chromatography, and the liquid products can be obtained by simulated distillation chromatography to obtain the mass fractions of pyrolysis gasoline (pyrolysis light gasoline and pyrolysis heavy gasoline), pyrolysis diesel and pyrolysis heavy oil.

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

[0138] Example 2

[0139] like Figure 1 As shown, the Kuwait crude oil in Table 1 is subjected to actual boiling point distillation to separate light distillate oil, middle distillate oil and heavy distillate oil, wherein the cut point between the light distillate oil and the middle distillate oil is 200°C, and the cut point between the middle distillate oil and the heavy distillate oil is 300°C.

[0140] The middle distillate oil is extracted and separated in the first separation unit by using ionic liquid as solvent, the cation is dialkyl substituted imidazolium cation, the alkyl groups are methyl and hexyl respectively, and the anion is hexafluorophosphate anion to obtain the first saturated fraction and the first unsaturated fraction, wherein 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 aromatic hydrocarbons in the first unsaturated fraction is 92.4%, which is a high-quality raw material for producing high-octane gasoline components or aromatic components.

[0141] The first unsaturated fraction is sent to the hydrogenation unit, and after hydrogenation and upgrading, it is sent back to the fluidized bed reactor of the catalytic cracking unit to be further converted into high-value products.

[0142] The heavy distillate oil is sent to the second separation unit using propane as the solvent, and is separated by supercritical extraction to obtain the second saturated fraction and the second unsaturated fraction, wherein the yield of the second saturated fraction is 76.2%, the mass fraction of saturated hydrocarbons in the second saturated fraction is 52.4%, the heavy metal removal rate is above 96%, and the second unsaturated fraction can be used as a raw material for road asphalt.

[0143] A fluidized bed reactor device is used to conduct a catalytic cracking reaction test of saturated fractions of different distillation ranges. Before the test, the catalyst is first loaded into the reactor, and the reactor is heated to the reaction temperature while the catalyst is kept in a fluidized state. The catalytic cracking raw materials including light distillate oil, the first saturated fraction, the second saturated fraction, the hydrogenated first unsaturated fraction, and the difficult-to-convert component light gasoline (the cracked light gasoline obtained by separation of catalytic cracking products) are allowed to enter the fluidized bed reactor device. The raw materials are mixed with high-temperature water vapor after preheating and enter the bottom of the fluidized reaction bed through the feed nozzle. The difficult-to-convert component butene (from the separation of gas products) enters the bottom of the fluidized bed reactor from the gas feed pipeline through the feed nozzle. All reaction raw materials react on the hot catalyst. After the reaction, water vapor is introduced for stripping, and the reaction oil and gas enter the multi-stage condensation separation system for separation to obtain cracking gas products and liquid products. The yields of the gas products and liquid products are measured. The gas products are separated to obtain ethylene, propylene, butene and remaining components. After the reaction is completed, the reactor is automatically heated to the regeneration temperature, and oxygen is introduced into the reactor to regenerate the catalyst. 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 flue gas flow integral. The gas products are collected and distributed by offline chromatography, and the liquid products can be obtained by simulated distillation chromatography to obtain the mass fractions of pyrolysis gasoline (pyrolysis light gasoline and pyrolysis heavy gasoline), pyrolysis diesel and pyrolysis heavy oil.

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

[0145] Comparative Example 1

[0146] This comparative example is a crude oil direct catalytic cracking test. Using Kuwait crude oil and DMMC-2 catalyst shown in Table 1, a fixed fluidized bed reactor test device was used to carry out a crude oil catalytic cracking reaction test. Before the test, the catalyst was first loaded into the reactor, and the reactor was heated to the reaction temperature while the catalyst was kept in a fluidized state. The crude oil was mixed with high-temperature water vapor after preheating, and entered the bottom of the fluidized reactor bed through a feed nozzle to react on the hot catalyst. After the reaction, water vapor was introduced for stripping, and the reaction oil and gas entered a multi-stage condensation separation system for separation to obtain cracking gas products and liquid products. The gas products and liquid products were measured to obtain yields. After the reaction was completed, the reactor was automatically heated to the regeneration temperature, and oxygen was introduced into the reactor to regenerate the catalyst to be regenerated. 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 integral. The gas products were collected and distributed by offline chromatography, and the liquid products were used to obtain the mass fractions of cracked gasoline, cracked diesel and cracked heavy oil by simulated distillation chromatography. The reaction conditions and product distribution are listed in Tables 2 and 3.

[0147] From the results in Table 3, it can be seen that the ethylene yield of this comparative example is only 5.56% by weight, the propylene yield is only 15.85% by weight, the high value-added product yield is 39.04% by weight, and the coke yield is 13.12% by weight.

[0148] Comparative Example 2

[0149] The Kuwait crude oil is separated into light distillate oil, middle distillate oil and heavy distillate oil by actual boiling point distillation, wherein the cut point between the light distillate oil and the middle distillate oil is 200°C, and the cut point between the middle distillate oil and the heavy distillate oil is 300°C.

[0150] The catalytic cracking reaction test of crude oil distillates with different distillation ranges was carried out using a fluidized bed reactor test device. Before the test, the catalyst was first loaded into the reactor, and the reactor was heated to the reaction temperature while the catalyst was kept in a fluidized state. The crude oil distillates with different distillation ranges were mixed with high-temperature water vapor in the order of light distillate, middle distillate and heavy distillate, and were preheated and entered the bottom of the fluidized reactor bed through a feed nozzle to react on the hot catalyst. After the reaction, water vapor was introduced for stripping, and the reaction oil and gas entered a multi-stage condensation separation system for separation to obtain cracking gas products and liquid products, and the yields of the gas products and liquid products were measured. After the reaction was completed, the reactor was automatically heated to the regeneration temperature, and oxygen was introduced into the reactor to regenerate the catalyst to be regenerated by burning. 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 integral. The gas products were collected and distributed by offline chromatography, and the liquid products were used to obtain the mass fraction of cracked gasoline, cracked diesel and cracked heavy oil by simulated distillation chromatography. The reaction conditions and product distribution are listed in Tables 2 and 3.

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

[0152] Table 2 Reaction conditions of Examples and Comparative Examples

[0153]

[0154]

[0155] The amount of water vapor used in Table 2, in weight %, represents the proportion of water vapor in the total weight of the catalytic cracking feedstock.

[0156] Catalytic cracking feed, weight %, represents the total feed of catalytic cracking minus the difficult-to-convert components (butene components and cracked light gasoline). The weight percentage of the difficult-to-convert components or the first unsaturated components of hydrogenation in the catalytic cracking feed does not include the difficult-to-convert components (butene components and cracked light gasoline).

[0157] Table 3 Comparison of reaction results between 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% by weight. After hydrogenation in the hydrogenation unit, the fraction is sent to the catalytic cracking unit for 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] It can be seen from the results of the above embodiments and comparative examples that when the process method and system of the present application are used for catalytic cracking of crude oil, the yields of ethylene and propylene are significantly improved, and the yield of high value-added products is high, that is, the utilization rate of crude oil atoms is high.

[0161] In the description of the present application, it should be noted that the terms "upper", "lower", "inside", "outside", "front", "back", "left", "right", etc. indicate directions or positional relationships based on the directions or positional relationships in the working state of the present application. They are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they should not be understood as limitations on the present application.

[0162] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "install", "connect" and "connect" should be understood in a broad sense. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0163] The present application has been described above in conjunction with preferred embodiments, but these embodiments are only exemplary and serve only as an illustration. On this basis, various replacements and improvements may be made to the present application, all of which fall within the scope of protection of the present application.

Claims

1. A process for selective separation and catalytic cracking of crude oil, characterized in that: The process comprises the following steps: (1) subjecting crude oil to distillation and cutting to obtain light oil, intermediate oil and heavy oil; wherein the cutting point between the light oil and the intermediate oil is 160-220° C., and the cutting point between the intermediate oil and the heavy oil is 260-320° C.; (2) subjecting the intermediate oil to a first separation to obtain a first saturated fraction and a first unsaturated fraction; (3) subjecting the heavy oil to a second separation to obtain a second saturated fraction and a second unsaturated fraction; (4) contacting the catalytic cracking feedstock with the catalyst to carry out a catalytic cracking reaction, and obtaining cracking gas, cracking light gasoline, cracking heavy gasoline, cracking diesel and cracking heavy oil through oil and gas separation; The catalytic cracking feedstock comprises the light oil, the first saturated fraction, the second saturated fraction and optional difficult-to-convert components, and the difficult-to-convert components include light hydrocarbons and / or light distillate oil.

2. The process according to claim 1, characterized in that: The crude oil in step (1) is selected from one or a mixture of paraffin-based, paraffin-intermediate-based, intermediate-paraffin-based, intermediate-based and intermediate-cycloalkyl crude oils; and / or The crude oil meets at least one of the following indicators: Density at 20°C is 800-935 kg / m 3 , API gravity is less than 30, UOP K value is not greater than 12.0, and metal content is greater than 30 mg / kg.

3. The process according to claim 1, characterized in that: 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; The thermal stability of the ionic liquid is higher than 250°C; Wherein, 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(trifluoromethylsulfonyl)imide; The first solvent is selected from one or more combinations of furfural, dimethyl sulfoxide, N,N-dimethylformamide, N,N-diethylformamide and morpholine; The conditions for the first extraction separation include: a temperature of 15-120° C., a pressure of 0.1-0.5 MPa, and a weight ratio of the ionic liquid to the intermediate oil, or a weight ratio of the first solvent to the intermediate oil, each independently being (1-15):

1.

4. The process according to claim 1, characterized in that: The second separation in step (3) includes: contacting the heavy oil with a second solvent to perform supercritical extraction separation; Wherein, the second solvent is selected from low carbon alkanes; the low carbon alkanes are selected from one or a mixture of ethane, propane, propylene, n-butane, isobutane, n-pentane, isopentane, hexane, heptane and octane; The conditions for the supercritical extraction separation include: a temperature of 50-100° C., 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 according to claim 1, characterized in that: The process also includes the following steps: The first unsaturated fraction from step (2) is used as a raw material for producing high-octane gasoline and / or aromatics; and / or, Using the second unsaturated fraction from step (3) as a raw material for producing needle coke and / or road asphalt; and / or, The cracked gas from step (4) is separated to obtain ethylene, propylene, butene and remaining components.

6. The process according to claim 5, characterized in that: The light hydrocarbons of the difficult-to-convert components include a gaseous hydrocarbon product rich in C4 fraction, preferably including butene obtained by separation of the cracked gas; The light distillate oil of the difficult-to-convert components includes self-produced light distillate oil with a final boiling point of less than 280-360°C and one or more of the following fractions: straight-run naphtha, straight-run kerosene, straight-run diesel produced by other primary processing units, topped oil, raffinate oil, hydrocracking light naphtha, pentane oil, coker gasoline, Fischer-Tropsch synthetic oil, catalytic cracking light gasoline, hydrogenated gasoline and hydrogenated diesel produced by other secondary processing units; And / or, the light distillate oil of the difficult-to-convert components preferably includes the pyrolysis light gasoline obtained from step (4); The weight proportion of butene and cracked light gasoline as the difficult-to-convert components in the catalytic cracking feedstock is independently 5-20%.

7. The process according to claim 6, characterized in that: The process also includes the following steps: subjecting the first unsaturated fraction from step (2) to a hydrogenation reaction to obtain a hydrogenated first unsaturated fraction; The catalytic cracking feedstock in step (4) also includes the hydrogenated first unsaturated fraction; The weight proportion of the hydrogenated first unsaturated component in the catalytic cracking feedstock is 0.1-10%.

8. The process according to claim 1, characterized in that: The conditions for the catalytic cracking reaction in step (4) include: The catalytic cracking raw material is mixed with water vapor and then fed, wherein the reaction temperature is 510-650° C., the reaction time is 1-20 seconds, the weight ratio of the catalyst to the catalytic cracking raw material is (3-50):1, and the weight ratio of the water vapor to the catalytic cracking raw material is (0.03-0.8):1; and / or, The catalyst comprises the following components, based on the dry weight of the components and the catalyst: 1-50 wt% zeolite, 5-99 wt% inorganic oxide, and 0-70 wt% clay; Preferably 5-45 wt% zeolite, 10-80 wt% inorganic oxide, and 5-60 wt% clay; More preferably, it is 10-40 wt% of zeolite, 20-70 wt% of inorganic oxide, and 10-50 wt% of clay.

9. A system for selective separation and catalytic cracking of crude oil, characterized in that: The system comprises 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 inlet of the material to be separated of the first separation unit (202), and the first separation unit (202) is also provided with a first saturated fraction outlet (202b) and a first unsaturated fraction outlet (202c); The heavy fraction oil outlet (203a) of the distillation unit (100) is connected to the inlet of the material to be separated of the second separation unit (203), and the second separation unit (203) is also provided with a second saturated fraction outlet (203b) and a second unsaturated fraction outlet (203c); The light fraction 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 cracking gas outlet (401), a cracking light gasoline outlet (402), a cracking heavy gasoline outlet (403), a cracking diesel outlet (404) and a cracking heavy oil outlet (405).

10. The system according to claim 9, characterized in that The system is also provided with a high-octane gasoline production unit and / or an aromatics production unit, and the first unsaturated outlet (202c) is connected to the raw material inlet of the high-octane gasoline production unit and / or the raw material inlet of the aromatics production unit; and / or, The system is further provided with a needle coke production unit and / or a road asphalt production unit, and 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 cracked gas outlet (401) of the catalytic cracking reaction unit (400) is connected to the gas inlet to be separated of the gas separation unit, and the gas separation unit is also provided with an ethylene outlet, a propylene outlet, a butene outlet and a remaining component outlet.

11. The system according to claim 10, characterized in that The catalytic cracking reaction unit (400) is further provided with a difficult-to-convert component inlet (406), and the difficult-to-convert component inlet (406) is connected to the cracking 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 fraction 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).

12. The system according to claim 9, characterized in that The first separation unit (202) is an extraction separation unit, and the second separation unit (203) is a supercritical extraction separation unit; The catalytic cracking reaction unit (400) is selected from one or a combination of reactors selected from fluidized bed, turbulent bed, fast bed and dilute phase transport bed; the reactor is selected from one or a series combination of constant linear velocity reactor, constant diameter reactor, variable diameter reactor, upward transport line reactor and downward transport line reactor.

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