A crude oil processing method and system for maximizing the production of chemical products and marine fuel.

Abstract

This invention relates to a crude oil processing method that maximizes the production of chemical products and also produces marine fuel. The method involves hydrocracking gasoline, second cracked gasoline, and third cracked gasoline, followed by cracked gasoline hydrotreating and extraction to obtain C6-C8 aromatics; ethane cracking of first, second, and third cracked dry gas to obtain ethylene; gas separation of first, second, and third cracked liquefied gas to obtain a first stream of propylene, propane, and a C4 mixture; propane dehydrogenation to obtain a second stream of propylene; and blending of cracked slurry oil and a portion of the residue with hydrotreated heavy oil to produce low-sulfur marine fuel at low cost. This invention achieves catalytic cracking of each fraction of crude oil, improving resource utilization efficiency and facilitating the maximization of low-carbon olefins and C6-C8 aromatics production while simultaneously producing marine fuel, thereby increasing the yield of these products.

Description

Technical Field

[0001] This invention relates to the field of petrochemicals, and more specifically, to a crude oil processing method and system that maximizes the production of chemical products and also produces marine fuel. Background Technology

[0002] Currently, refined oil production capacity is already in a state of oversupply. With the continuous increase in refining capacity and the accelerated impact of new energy sources, the trend of oversupply of refined oil will continue to intensify in the future.

[0003] For the refined oil market, diesel consumption has reached its peak, and gasoline demand is expected to peak as well. Meanwhile, there is a severe shortage of basic organic chemical raw materials such as aromatics and ethylene. Currently, the proportion of chemical demand in petroleum consumption is increasing year by year. The surplus of refined oil and the shortage of organic chemical raw materials make the transformation and upgrading of oil refining enterprises from "fuel-oriented" to "chemical-oriented" an inevitable trend.

[0004] Marine fuel oil is fuel oil used in marine internal combustion engines. my country's national standard GB17411-2015 classifies marine fuel oil into Group D (distillate fuel oil, marine light oil) and Group R (residual fuel oil, marine heavy oil). Residual marine fuel oil is often referred to as heavy marine fuel oil and is mainly used in low-speed diesel engines as propulsion power for ships. To control pollution from ships, according to the International Convention for the Prevention of Pollution from Ships (ICMO), the sulfur content of global low-sulfur heavy marine fuel oil (hereinafter referred to as low-sulfur marine fuel) must not exceed 0.5%. The consumption of low-sulfur marine fuel is steadily increasing. During the chemical industry transformation, using hydrocarbons that are not easily cracked as marine fuel oil and fully utilizing refinery resources for the production of low-sulfur marine fuel can also help release refining capacity.

[0005] In existing crude oil processing, traditional refineries mainly produce fuel oils such as gasoline, kerosene, and diesel, with small amounts of propylene and aromatics as byproducts. The yield of chemical products is low, and the crude oil conversion rate is not high, which cannot meet the growing demand for organic chemical raw materials. However, by utilizing existing refining and chemical technologies to design refineries that produce all chemical products, and maximizing the yield of chemical products while producing marine fuels, it is possible to break the traditional refinery process and provide guidance for the chemical transformation of existing refineries.

[0006] For example, patent documents CN113817500A, CN113817502A, CN113817505A, etc., describe processes such as first directional upgrading of crude oil, and then selective hydrogenation, adsorption separation, aromatics production enhancement, and olefins production enhancement.

[0007] However, the proportion of non-chemical products other than ethylene, propylene, and C6-C8 aromatics in the products obtained from existing crude oil processing methods in refineries remains relatively high. Summary of the Invention

[0008] The purpose of this invention is to further increase the proportion of ethylene, propylene and C6-C8 aromatics in the products obtained by crude oil processing methods, while also taking into account the production of marine fuel, so as to significantly improve crude oil conversion efficiency.

[0009] To achieve the above objectives, a first aspect of the present invention provides a crude oil processing method that maximizes the production of chemical products and also produces marine fuel, the method comprising the following steps:

[0010] S1. Separate the crude oil to obtain naphtha fraction, straight-run diesel fraction and atmospheric residue fraction;

[0011] S2. Hydrogenate the atmospheric residue fraction to obtain hydrogenated diesel oil and hydrogenated heavy oil; separate a first stream of hydrogenated heavy oil and a second stream of hydrogenated heavy oil from the hydrogenated heavy oil; subject the first stream of hydrogenated heavy oil to a first catalytic cracking to obtain a first cracked dry gas, a first cracked liquefied gas, a first cracked gasoline, a first cracked diesel oil, and a cracked slurry; mix the second stream of hydrogenated heavy oil with the cracked slurry to obtain marine fuel;

[0012] S3. Hydrorefining the straight-run diesel fraction and the hydrotreated residue diesel to obtain refined diesel; subjecting the refined diesel to a second catalytic cracking to obtain second cracked dry gas, second cracked liquefied gas, second cracked gasoline, and second cracked diesel.

[0013] S4. The naphtha fraction and the first cracked gasoline are subjected to third catalytic cracking to obtain third cracked dry gas, third cracked liquefied gas and third cracked gasoline.

[0014] S5. The first cracked diesel and the second cracked diesel are subjected to hydrocracking to obtain hydrocracking gasoline and hydrocracking diesel; the hydrocracking diesel is returned to the first catalytic cracking in step S2; the hydrocracking gasoline, the second cracked gasoline, and the third cracked gasoline 131 are subjected to cracked gasoline hydrotreating and cracked gasoline extraction to obtain C6-C8 aromatics, raffinate, and heavy aromatics of C9 and above; the raffinate is returned to the third catalytic cracking in step S4; the heavy aromatics are returned to the hydrocracking in step S5.

[0015] S6. The first cracked dry gas, the second cracked dry gas and the third cracked dry gas are subjected to ethane cracking treatment to obtain ethylene;

[0016] S7. The first cracked liquefied gas, the second cracked liquefied gas, and the third cracked liquefied gas are separated into gas fractions to obtain a first stream of propylene, propane, and C4 mixed hydrocarbons; the propane is subjected to propane dehydrogenation to obtain a second stream of propylene; the C4 mixed hydrocarbons are subjected to a superposition reaction to obtain superposition oil and remaining C4 hydrocarbons; the superposition oil is returned to the third catalytic cracking in step S4; the remaining C4 hydrocarbons are subjected to light hydrocarbon conversion to produce propane to obtain propane conversion gas; the propane conversion gas is returned to the gas fractionation in step S7.

[0017] Optionally, in step S7, the gas separation also yields at least one of 1-butene, 2-butene, and butadiene.

[0018] Optionally, in step S1, the cut-off point between the naphtha fraction and the straight-run diesel fraction is any temperature between 175-205℃, and the cut-off point between the straight-run diesel fraction and the atmospheric residue fraction is any temperature between 335-370℃.

[0019] Optionally, in step S2, the reaction conditions for the hydrotreating include: a reaction temperature of 300-460℃, a reaction pressure of 6-25MPa, and a hydrogen-to-oil volume ratio of (100-1500):1; the separation point between hydrotreated diesel and hydrotreated heavy oil is any temperature between 335-370℃.

[0020] Optionally, the first catalytic cracking conditions include: a reaction temperature of 400–650°C, a reaction pressure of 0.05–1 MPa, and a catalyst-to-oil weight ratio of (5–50):1; the separation point between the first cracked dry gas and the first cracked liquefied gas is any temperature between 14–16°C, the separation point between the first cracked liquefied gas and the first cracked gasoline is any temperature between 38–62°C, and the separation point between the first cracked gasoline and the first cracked diesel is any temperature between 175–205°C; the weight ratio between the first stream of hydrotreated heavy residue oil and the second stream of hydrotreated heavy residue oil is (1–15):1.

[0021] Optionally, in step S3, the reaction conditions for hydrorefining include: a reaction temperature of 200-400℃, a reaction pressure of 2-16MPa, and a hydrogen-to-oil volume ratio of (400-1000):1.

[0022] Optionally, the second catalytic cracking conditions include: a reaction temperature of 500–750°C, a reaction pressure of 0.05–1 MPa, and a catalyst-to-oil weight ratio of (5–100):1, preferably (10–50):1; the separation point between the second cracked dry gas and the second cracked liquefied gas is any temperature between 14–16°C, the separation point between the second cracked liquefied gas and the second cracked gasoline is any temperature between 38–62°C, and the separation point between the second cracked gasoline and the second cracked diesel is any temperature between 175–205°C.

[0023] Optionally, in step S4, the third catalytic cracking conditions include: a reaction temperature of 500–750°C, a reaction pressure of 0.05–1 MPa, and a catalyst-to-oil weight ratio of (5–100):1, preferably (10–50):1; the separation point between the third cracked dry gas and the third cracked liquefied gas is any temperature between 14–16°C, and the separation point between the third cracked liquefied gas and the third cracked gasoline is any temperature between 38–62°C.

[0024] Optionally, in step S5, the reaction conditions for the hydrocracking treatment include: a reaction temperature of 260–500 °C, a hydrogen partial pressure of 3–10 MPa, and a volume hourly space velocity of 0.5–6 h⁻¹. -1 The separation point between hydrocracked gasoline and hydrocracked diesel is any temperature between 175-205℃.

[0025] Optionally, the reaction conditions for the hydrotreating of the cracked gasoline include: a reaction temperature of 300-400℃ in the hydrotreating unit, a reaction pressure of 4-16MPa, and a hydrogen-to-oil volume ratio of (300-1000):1. The conditions for the extraction of the cracked gasoline include: a temperature of 20-100℃, a pressure of 0.05-0.5MPa, and a weight ratio of extraction solvent to feedstock oil of (0.5-2.5):1.

[0026] Optionally, in step S6, the reaction conditions for the ethane cracking treatment include: a reaction pressure of 0.10–0.25 MPa, a reaction temperature of 810–870 °C, and a residence time of 0.25–0.4 s.

[0027] Optionally, in step S7, the reaction conditions for the propane dehydrogenation treatment include: a reaction temperature of 400–700°C, a reaction pressure of 0.05–1 MPa, a reaction time of 40–60 h, and a propane mass hourly space velocity of 2–9 h⁻¹. -1 .

[0028] Optionally, the reaction conditions for the superposition reaction include: a reaction temperature of 40–350°C, preferably 200–300°C, a reaction pressure of 0.5–10 MPa, and a mass hourly space velocity of 0.2–20 h⁻¹. -1The separation point between the composite oil and the remaining C4 hydrocarbons is any temperature between 30-65°C.

[0029] Optionally, the reaction conditions for converting light hydrocarbons to propane include: a reaction temperature of 250–550°C, a reaction pressure of 0.1–2 MPa, and a mass hourly space velocity of 0.1–3 h⁻¹. -1 .

[0030] A second aspect of the present invention provides a crude oil processing system that maximizes the production of chemical products and also produces marine fuel. The system includes: an atmospheric pressure unit, a third catalytic cracking unit, a diesel hydrorefining unit, a residue hydrorefining unit, an ethane cracking unit, a gas separation unit, a second catalytic cracking unit, a first catalytic cracking unit, a cracked gasoline hydrorefining unit, a cracked gasoline extraction unit, a catalytic diesel hydrocracking to aromatics unit, a propane dehydrogenation unit, a superposition unit, and a light hydrocarbon conversion to propane unit.

[0031] Optionally, the naphtha fraction outlet of the atmospheric pressure unit is connected to the third catalytic cracking inlet of the third catalytic cracking unit; the third cracked dry gas outlet of the third catalytic cracking unit is connected to the cracked dry gas inlet of the ethane cracking unit.

[0032] Optionally, the straight-run diesel fraction outlet of the atmospheric pressure unit is connected to the first diesel hydrorefining inlet of the diesel hydrorefining unit, and the refined diesel outlet of the diesel hydrorefining unit is connected to the refined diesel inlet of the second catalytic cracking unit.

[0033] Optionally, the atmospheric residue oil fraction outlet of the atmospheric pressure unit is connected to the atmospheric residue oil fraction inlet of the residue hydrotreating unit; the residue hydrotreated diesel oil outlet of the residue hydrotreating unit is connected to the second diesel hydrotreating inlet of the diesel hydrotreating unit; the first stream of residue hydrotreated heavy oil outlet of the residue hydrotreating unit is connected to the residue hydrotreated heavy oil inlet of the first catalytic cracking unit; and the second stream of residue hydrotreated heavy oil outlet of the residue hydrotreating unit is connected to the cracked slurry outlet of the first catalytic cracking unit. The first cracked dry gas outlet of the first catalytic cracking unit and the second cracked dry gas outlet of the second catalytic cracking unit are respectively connected to the connecting pipelines between the third cracked dry gas outlet of the third catalytic cracking unit and the cracked dry gas inlet of the ethane cracking unit.

[0034] Optionally, the second liquefied petroleum gas (LPG) outlet of the second catalytic cracking unit is connected to the first LPG inlet of the gas separation unit; the third LPG outlet of the third catalytic cracking unit is connected to the connecting pipeline between the first LPG outlet of the first catalytic cracking unit and the second LPG outlet and the first LPG inlet, respectively; the third gasoline outlet of the third catalytic cracking unit is connected to the gasoline inlet of the gasoline hydrotreating unit; the second gasoline outlet of the second catalytic cracking unit is connected to the connecting pipeline between the third gasoline outlet and the first gasoline inlet; and the first gasoline outlet of the first catalytic cracking unit is connected to the third catalytic cracking inlet.

[0035] Optionally, the first cracked diesel outlet of the first catalytic cracking unit is connected to the first cracked diesel inlet of the catalytic diesel hydrocracking to aromatics unit; the second cracked diesel outlet of the second catalytic cracking unit is connected to the connecting pipeline between the first cracked diesel outlet and the first cracked diesel inlet; the hydrocracking gasoline outlet of the catalytic diesel hydrocracking to aromatics unit is connected to the cracked gasoline inlet of the cracked gasoline hydrotreating unit; and the hydrocracking diesel outlet of the catalytic diesel hydrocracking to aromatics unit is connected to the first catalytic cracking inlet of the first catalytic cracking unit.

[0036] Optionally, the propane outlet of the gas separation unit is connected to the propane inlet of the propane dehydrogenation unit, and the first propylene outlet of the gas separation unit is connected to the second propylene outlet of the propane dehydrogenation unit.

[0037] Optionally, the product outlet of the cracked gasoline hydrogenation unit is connected to the feed inlet of the cracked gasoline extraction unit.

[0038] Optionally, the residual oil outlet of the cracked gasoline extraction unit is connected to the connecting pipeline between the naphtha fraction outlet and the third catalytic cracking inlet; the heavy aromatics outlet of the cracked gasoline extraction unit is connected to the heavy aromatics inlet of the catalytic diesel hydrocracking to aromatics unit.

[0039] Optionally, the C4 mixed hydrocarbon outlet of the gas separation unit is connected to the C4 mixed hydrocarbon inlet of the superposition unit, and the superposition oil outlet of the superposition unit is connected to the connecting pipeline between the naphtha fraction outlet and the third catalytic cracking inlet; the remaining C4 hydrocarbon outlet of the superposition unit is connected to the remaining C4 hydrocarbon inlet of the light hydrocarbon conversion to propane unit, and the propane conversion gas outlet of the light hydrocarbon conversion to propane unit is connected to the second cracked liquefied gas inlet of the gas separation unit.

[0040] Through the above technical solutions, this invention provides a crude oil processing method and system for producing all chemical products. This invention introduces crude oil into an atmospheric pressure unit for atmospheric separation, obtaining naphtha, diesel, and atmospheric residue fractions, which facilitates catalytic cracking reactions of each fraction. Catalytic cracking of naphtha, diesel, and atmospheric residue fractions improves the yields of ethylene, propylene, and C6-C8 aromatics. The invention feeds cracked dry gas into an ethane cracking unit to increase ethylene yield. Propane from the gas fraction undergoes propane dehydrogenation to improve propylene yield. Furthermore, the invention can further process cracked diesel from the cracking products through catalytic diesel hydrocracking, returning it as hydrocracking gasoline to the cracked gasoline hydrocracking unit and extraction unit for extraction and separation, thus improving aromatics yield. Cracking slurry and some of the residue hydrocracking heavy oil are blended to produce low-sulfur marine fuel at low cost. Additionally, the invention can return liquefied petroleum gas from the gas fraction to the light oil catalytic cracking unit and gas fraction unit after passing through a superposition and light hydrocarbon conversion propane unit, further improving chemical product yields. This invention enables catalytic cracking of crude oil fractions, improves resource utilization efficiency, and facilitates the maximization of low-carbon olefins and C6-C8 aromatics production while also considering marine fuel production. It also enables a production scheme that produces only chemical products without producing any oil products.

[0041] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0042] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the following detailed description to explain the invention, but do not constitute a limitation thereof. In the drawings:

[0043] Figure 1 This is a schematic diagram of a crude oil processing system that maximizes the production of chemical products and also produces marine fuel, as provided by the present invention.

[0044] Explanation of reference numerals in the attached figures

[0045] 9-Atmospheric pressure unit, 10-Third catalytic cracking unit, 11-Diesel hydrorefining unit, 12-Residue oil hydrorefining unit, 13-Ethane cracking unit, 14-Gas separation unit, 15-Second catalytic cracking unit, 16-First catalytic cracking unit, 17-Cracked gasoline hydrorefining unit, 18-Catalytic diesel hydrocracking to aromatics unit, 19-Propane dehydrogenation unit, 20-Synthesis unit, 21-Light hydrocarbon conversion to propane unit, 22-Cracked gasoline extraction unit;

[0046] 125 - Crude oil, 126 - Naphtha fraction, 127 - Straight-run diesel fraction, 128 - Atmospheric residue fraction, 129 - Third crack dry gas, 130 - Third crack liquefied petroleum gas (LPG), 131 - Third crack gasoline, 132 - Refined diesel, 133 - Hydrotreated residue diesel, 134 - Hydrotreated residue heavy oil, 135 - Propane, 136 - C4 LPG, 137 - Second crack dry gas, 138 - Second crack LPG, 139 - Second crack gasoline, 140 - Second crack Diesel fuel, 141-First cracked dry gas, 142-First cracked liquefied petroleum gas, 143-First cracked gasoline, 144-First cracked diesel fuel, 145-Raffinate oil, 146-Heavy aromatics, 147-Hydrocracked gasoline, 148-Hydrocracked diesel fuel, 149-Ethylene, 150-Propylene, 151-C6-C8 aromatics, 152-Cracked slurry oil, 153-Low sulfur heavy marine fuel oil, 154-Blended oil, 155-Residual C4 hydrocarbons, 156-Propane reforming gas. Detailed Implementation

[0047] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0048] In this invention, unless otherwise stated, the terms "first," "second," etc., are used only to distinguish different components and do not imply any actual meaning such as the order of connection. In this invention, directional terms such as "upper," "lower," "left," and "right" refer to the upper and lower, left and right positions of the device in its normal operating state, while "inner" and "outer" refer to the outline of the device.

[0049] The first aspect of this invention provides a crude oil processing method that maximizes the production of chemical products and also produces marine fuel, the method comprising the following steps:

[0050] S1. Separate crude oil 125 to obtain naphtha fraction 126, straight-run diesel fraction 127 and atmospheric residue fraction 128.

[0051] S2. Hydrotreating the atmospheric residue fraction 128 yields hydrotreated diesel oil 133 and hydrotreated heavy residue oil 134. Separating a first hydrotreated heavy residue oil stream and a second hydrotreated heavy residue oil stream from the hydrotreated heavy residue oil 134, subjecting the first hydrotreated heavy residue oil stream to first catalytic cracking to obtain first cracked dry gas 141, first cracked liquefied petroleum gas 142, first cracked gasoline 143, first cracked diesel oil 144, and cracked slurry oil 152. Mixing the second hydrotreated heavy residue oil stream with the cracked slurry oil 152 yields marine fuel 153.

[0052] S3. Hydrorefining the straight-run diesel fraction 127 and the residual oil hydrotreated diesel 133 to obtain refined diesel 132; subjecting the refined diesel 132 to a second catalytic cracking to obtain second cracked dry gas 137, second cracked liquefied petroleum gas 138, second cracked gasoline 139, and second cracked diesel 140.

[0053] S4. The naphtha fraction 126 and the first cracked gasoline 143 are subjected to third catalytic cracking to obtain third cracked dry gas 129, third cracked liquefied gas 130 and third cracked gasoline 131.

[0054] S5. The first cracked diesel oil 144 and the second cracked diesel oil 140 are subjected to hydrocracking to obtain hydrocracking gasoline 147 and hydrocracking diesel oil 148; the hydrocracking diesel oil 148 is returned to the first catalytic cracking in step S2; the hydrocracking gasoline 147, the second cracked gasoline 139, and the third cracked gasoline 131 are subjected to cracked gasoline hydrotreating and cracked gasoline extraction to obtain C6-C8 aromatics 151, raffinate oil 145, and heavy aromatics 146; the raffinate oil 145 is returned to the third catalytic cracking in step S4; the heavy aromatics 146 is returned to the hydrocracking in step S5.

[0055] S6. The first cracked dry gas 141, the second cracked dry gas 137 and the third cracked dry gas 129 are subjected to ethane cracking treatment to obtain ethylene 149.

[0056] S7. The first cracked liquefied gas 142, the second cracked liquefied gas 138, and the third cracked liquefied gas 130 are separated into gas fractions to obtain a first stream of propylene 150, propane 135, and C4 mixed hydrocarbons 136. The propane 135 is subjected to propane dehydrogenation to obtain a second stream of ethylene 149 and a second stream of propylene 150. The C4 mixed hydrocarbons 136 are subjected to a superposition reaction to obtain superposition oil 154 and the remaining C4 hydrocarbons 155. The superposition oil 154 is returned to the third catalytic cracking in step S4. The remaining C4 hydrocarbons 155 are subjected to light hydrocarbon conversion to propane to obtain propane conversion gas 156. The propane conversion gas 156 is returned to the gas fractionation in step S7.

[0057] In this invention, crude oil is introduced into an atmospheric pressure unit for atmospheric separation to obtain naphtha, straight-run diesel, and atmospheric residue fractions, which facilitates catalytic cracking reactions of each fraction. Catalytic cracking of naphtha, straight-run diesel, and atmospheric residue fractions improves the yields of ethylene, propylene, and C6-C8 aromatics. The cracked dry gas is fed into an ethane cracking unit to increase ethylene yield. Propane from the gas fraction undergoes propane dehydrogenation to improve propylene yield. Furthermore, the cracked diesel from the cracking products can be catalytically hydrocrackinged and then returned to the cracked gasoline hydrocracking unit and extraction unit for extraction and separation, further improving aromatics yield. The cracked slurry and some of the hydrocracking heavy oil from the residue are blended to produce low-sulfur marine fuel at low cost. Additionally, the liquefied petroleum gas from the gas fraction can be returned to the light oil catalytic cracking unit and gas fraction unit after passing through a superposition and light hydrocarbon conversion unit to produce propane, which improves chemical product yield. Meanwhile, returning the raffinate to the third catalytic cracking unit can further improve the yield of olefins; returning the heavy aromatics to the catalytic diesel hydrocracking to aromatics unit can further improve the yield of C6-C8 aromatics.

[0058] This invention enables catalytic cracking of crude oil fractions, improves resource utilization efficiency, and facilitates the maximization of low-carbon olefins and C6-C8 aromatics production while also considering marine fuel production. It also enables a production scheme that produces only chemical products without producing any oil products.

[0059] According to the present invention, optionally, in step S7, the gas separation further yields at least one of 1-butene, 2-butene, and butadiene.

[0060] According to the present invention, optionally, in step S1, the cut-off point between the naphtha fraction 126 and the straight-run diesel fraction 127 is any temperature between 175-205°C, and the cut-off point between the straight-run diesel fraction 127 and the atmospheric residue fraction 128 is any temperature between 335-370°C.

[0061] According to the present invention, optionally, in step S2, the reaction conditions for the hydrotreating include: a reaction temperature of 300-460°C, a reaction pressure of 6-25 MPa, and a hydrogen-to-oil volume ratio of (100-1500):1; the separation point between the hydrotreated diesel 133 and the hydrotreated heavy oil 134 is any temperature between 335-370°C; and the weight ratio between the first hydrotreated heavy oil and the second hydrotreated heavy oil is (1-15):1.

[0062] According to the present invention, optionally, the first catalytic cracking conditions include: a reaction temperature of 400-650°C, a reaction pressure of 0.05-1 MPa, and a catalyst-to-oil weight ratio of (5-50):1; the separation point between the first cracked dry gas 141 and the first cracked liquefied gas 142 is any temperature between 14-16°C, the separation point between the first cracked liquefied gas 142 and the first cracked gasoline 143 is any temperature between 38-62°C, and the separation point between the first cracked gasoline 143 and the first cracked diesel 144 is any temperature between 175-205°C.

[0063] According to the present invention, optionally, in step S3, the reaction conditions for hydrorefining include: a reaction temperature of 200-400°C, a reaction pressure of 2-16 MPa, and a hydrogen-to-oil volume ratio of (400-1000):1.

[0064] According to the present invention, optionally, the second catalytic cracking conditions include: a reaction temperature of 500-750°C, a reaction pressure of 0.05-1 MPa, and a catalyst-to-oil weight ratio of (5-100):1, preferably (10-50):1; the separation point between the second cracked dry gas 137 and the second cracked liquefied gas 138 is any temperature between 14-16°C, the separation point between the second cracked liquefied gas 138 and the second cracked gasoline 139 is any temperature between 38-62°C, and the separation point between the second cracked gasoline 139 and the second cracked diesel 140 is any temperature between 175-205°C.

[0065] According to the present invention, optionally, in step S4, the third catalytic cracking conditions include: a reaction temperature of 500-750°C, a reaction pressure of 0.05-1 MPa, and a catalyst-to-oil weight ratio of (5-100):1, preferably (10-50):1; the separation point between the third cracked dry gas 129 and the third cracked liquefied gas 130 is any temperature between 14-16°C, and the separation point between the third cracked liquefied gas 130 and the third cracked gasoline 131 is any temperature between 38-62°C.

[0066] According to the present invention, optionally, in step S5, the reaction conditions for the hydrocracking treatment include: a reaction temperature of 260–500°C, a hydrogen partial pressure of 3–10 MPa, and a volume hourly space velocity of 0.5–6 h⁻¹. -1 The separation cut-off point for hydrocracked gasoline 147 and hydrocracked diesel 148 is any temperature between 175-205℃.

[0067] According to the present invention, optionally, the reaction conditions for the hydrotreating of the cracked gasoline include: a hydrotreating unit reaction temperature of 300-400°C, a reaction pressure of 4-16 MPa, and a hydrogen-to-oil volume ratio of (300-1000):1; the conditions for the extraction of the cracked gasoline include: a temperature of 20-100°C, a pressure of 0.05-0.5 MPa, and a weight ratio of extraction solvent to feedstock oil of (0.5-2.5):1. The heavy aromatics are C9 or higher heavy aromatics.

[0068] According to the present invention, optionally, in step S6, the reaction conditions for the ethane cracking treatment include: a reaction pressure of 0.10 to 0.25 MPa, a reaction temperature of 810 to 870 °C, and a residence time of 0.25 to 0.4 s.

[0069] According to the present invention, optionally, in step S7, the reaction conditions for the propane dehydrogenation treatment include: a reaction temperature of 400–700 °C, a reaction pressure of 0.05–1 MPa, a reaction time of 40–60 h, and a propane mass hourly space velocity of 2–9 h⁻¹. -1 .

[0070] According to the present invention, optionally, the reaction conditions for the superposition reaction include: a reaction temperature of 40–350°C, a reaction pressure of 0.5–10 MPa, and a mass hourly space velocity of 0.2–20 h⁻¹. -1 The separation cut-off point between the composite oil 152 and the remaining C4 hydrocarbon 153 is any temperature between 30-65℃; the reaction conditions for the conversion of light hydrocarbons to propane are: reaction temperature of 250-550℃, reaction pressure of 0.1-2MPa, and mass hourly space velocity of 0.1-3h. -1 .

[0071] A second aspect of this invention provides a crude oil processing system that maximizes the production of chemical products and also produces marine fuel. This system includes: an atmospheric unit 9, a third catalytic cracking unit 10, a diesel hydrorefining unit 11, a residue hydrorefining unit 12, an ethane cracking unit 13, a gas separation unit 14, a second catalytic cracking unit 15, a first catalytic cracking unit 16, a cracked gasoline hydrorefining unit 17, a cracked gasoline extraction unit 22, a catalytic diesel hydrocracking to aromatics unit 18, a propane dehydrogenation unit 19, a superposition unit 20, and a light hydrocarbon conversion to propane unit 21. All the devices used in this invention are conventionally used in the art. During the processing of this invention, the third and second catalytic cracking units, due to the lighter feedstock, have insufficient heat supply themselves, which is provided by the cracked oil slurry and coke produced as byproducts of the first catalytic cracking unit.

[0072] According to the present invention, optionally, the naphtha fraction outlet of the atmospheric pressure device 9 is connected to the third catalytic cracking inlet of the third catalytic cracking device 10; the third cracked dry gas outlet of the third catalytic cracking device 10 is connected to the cracked dry gas inlet of the ethane cracking device 13.

[0073] According to the present invention, optionally, the straight-run diesel fraction outlet of the atmospheric pressure device 9 is connected to the first diesel hydrorefining inlet of the diesel hydrorefining device 11, and the refined diesel outlet of the diesel hydrorefining device 11 is connected to the refined diesel inlet of the second catalytic cracking device 15.

[0074] According to the present invention, optionally, the atmospheric residue oil fraction outlet of the atmospheric pressure unit 9 is connected to the atmospheric residue oil fraction inlet of the residue oil hydrotreating unit 12; the residue oil hydrotreated diesel oil outlet of the residue oil hydrotreating unit 12 is connected to the second diesel hydrotreated inlet of the diesel hydrotreated refining unit 11; the first residue oil hydrotreated heavy oil outlet of the residue oil hydrotreating unit 12 is connected to the residue oil hydrotreated heavy oil inlet of the first catalytic cracking unit 16; the second residue oil hydrotreated heavy oil outlet of the residue oil hydrotreating unit 16 is connected to the cracked slurry outlet of the first catalytic cracking unit 16; the first cracked dry gas outlet of the first catalytic cracking unit 16 and the second cracked dry gas outlet of the second catalytic cracking unit 15 are respectively connected to the connecting pipelines between the third cracked dry gas outlet of the third catalytic cracking unit 10 and the cracked dry gas inlet of the ethane cracking unit 13.

[0075] According to the present invention, optionally, the second liquefied petroleum gas (LPG) outlet of the second catalytic cracking unit 15 is connected to the first LPG inlet of the gas separation unit 14, and the third LPG outlet of the third catalytic cracking unit 10 and the first LPG outlet of the first catalytic cracking unit 16 are respectively connected to the connecting pipeline between the second LPG outlet and the first LPG inlet; the third gasoline outlet of the third catalytic cracking unit 10 is connected to the gasoline inlet of the gasoline hydrogenation unit 17, and the second gasoline outlet of the second catalytic cracking unit 15 is connected to the connecting pipeline between the third gasoline outlet and the first gasoline inlet.

[0076] According to the present invention, optionally, the first cracked gasoline outlet of the first catalytic cracking unit 16 is connected to the third catalytic cracking inlet; the first cracked diesel outlet of the first catalytic cracking unit 16 is connected to the first cracked diesel inlet of the catalytic diesel hydrocracking to aromatics unit 18; the second cracked diesel outlet of the second catalytic cracking unit 15 is connected to the connecting pipeline between the first cracked diesel outlet and the first cracked diesel inlet; the hydrocracking gasoline outlet of the catalytic diesel hydrocracking to aromatics unit 18 is connected to the cracked gasoline inlet of the cracked gasoline hydrotreating unit 17; and the hydrocracking diesel outlet of the catalytic diesel hydrocracking to aromatics unit 18 is connected to the first catalytic cracking inlet of the first catalytic cracking unit 16.

[0077] According to the present invention, optionally, the propane outlet of the gas separation unit 14 is connected to the propane inlet of the propane dehydrogenation unit 19, and the first propylene outlet of the gas separation unit 14 is connected to the second propylene outlet of the propane dehydrogenation unit 19.

[0078] According to the present invention, optionally, the product outlet of the cracked gasoline hydrogenation unit 17 is connected to the feed inlet of the cracked gasoline extraction unit 22.

[0079] According to the present invention, optionally, the raffinate outlet of the cracked gasoline extraction unit 22 is connected to the connecting pipeline between the naphtha fraction outlet and the third catalytic cracking inlet; the heavy aromatics outlet of the cracked gasoline extraction unit 22 is connected to the heavy aromatics inlet of the catalytic diesel hydrocracking to aromatics unit 18.

[0080] According to the present invention, optionally, the C4 mixed hydrocarbon outlet of the gas separation unit 14 is connected to the C4 mixed hydrocarbon inlet of the superposition unit 20, the superposition oil outlet of the superposition unit 20 is connected to the connecting pipeline between the naphtha fraction outlet and the third catalytic cracking inlet; the remaining C4 hydrocarbon outlet of the superposition unit 20 is connected to the remaining C4 hydrocarbon inlet of the light hydrocarbon conversion to propane unit 21, and the propane conversion gas outlet of the light hydrocarbon conversion to propane unit 21 is connected to the second cracked liquefied gas inlet of the gas separation unit 14.

[0081] The present invention will be further illustrated by the following examples, but the present invention is not limited thereto.

[0082] The crude oil used in Example 1 was Saudi medium crude oil with a density of 869.2 kg / m³. 3 The sulfur content is 2.6% by mass, and the acid value is 0.19 mg KOH / g.

[0083] Example 1

[0084] according to Figure 1The crude oil refining system shown here, which maximizes the production of chemical products and also produces marine fuels, produces low-carbon olefins and C6-C8 aromatics. The specific process is as follows:

[0085] S1. Separate crude oil 125 to obtain naphtha fraction 126, straight-run diesel fraction 127 and atmospheric residue fraction 128.

[0086] S2. The atmospheric residue fraction 128 is hydrotreated to obtain hydrotreated diesel oil 133 and hydrotreated heavy residue oil 134. A first hydrotreated heavy residue oil and a second hydrotreated heavy residue oil are separated from the hydrotreated heavy residue oil 134. The first hydrotreated heavy residue oil is subjected to a first catalytic cracking to obtain a first cracked dry gas 141, a first cracked liquefied petroleum gas 142, a first cracked gasoline 143, a first cracked diesel oil 144, and a cracked slurry oil 152. The second hydrotreated heavy residue oil is mixed with the cracked slurry oil 152 to obtain marine fuel 153. The hydrotreatment reaction temperature is 400°C, the pressure is 16 MPa, and the hydrogen-to-oil volume ratio is 800:1. The first catalytic cracking reaction temperature is 550°C, the reaction pressure is 0.35 MPa, and the catalyst-to-oil weight ratio is 30:1. The weight ratio between the first hydrotreated heavy residue oil and the second hydrotreated heavy residue oil is 13:1.

[0087] S3. Hydrorefining the straight-run diesel fraction 127 and the hydrotreated diesel residue 133 to obtain refined diesel 132; subjecting the refined diesel 132 to a second catalytic cracking to obtain second cracked dry gas 137, second cracked liquefied petroleum gas 138, second cracked gasoline 139, and second cracked diesel 140; wherein the hydrorefining reaction temperature is 300℃, the reaction pressure is 12MPa, and the hydrogen-to-oil volume ratio is 700:1; the second catalytic cracking reaction temperature is 650℃, the reaction pressure is 0.1MPa, and the catalyst-to-oil weight ratio is 11:1;

[0088] S4. The naphtha fraction 126 and the first cracked gasoline 143 are subjected to third catalytic cracking to obtain third cracked dry gas 129, third cracked liquefied gas 130 and third cracked gasoline 131; wherein the reaction temperature is 670℃, the reaction pressure is 0.1MPa, and the catalyst-to-gasoline weight ratio is 12:1.

[0089] S5. The first cracked diesel oil 144 and the second cracked diesel oil 140 are subjected to hydrocracking to obtain hydrocracking gasoline 147 and hydrocracking diesel oil 148; the hydrocracking diesel oil 148 is returned to the first catalytic cracking step S2; the hydrocracking gasoline 147, the second cracked gasoline 139, and the third cracked gasoline 131 are subjected to cracked gasoline hydrotreating and cracked gasoline extraction to obtain C6-C8 aromatics 151, raffinate oil 145, and C9 and above heavy aromatics 146; the raffinate oil 145 is returned to the third catalytic cracking step S4; the heavy aromatics 146 are returned to the hydrocracking step S5; wherein, the hydrocracking reaction temperature is 360°C, the hydrogen partial pressure is 6 MPa, and the volume hourly space velocity is 2 h⁻¹. -1 The hydrogenation unit for treating cracked gasoline has a reaction temperature of 350°C, a reaction pressure of 10 MPa, and a hydrogen-to-oil volume ratio of 600:1. The extraction temperature of the cracked gasoline is 40°C, the pressure is 0.1 MPa, and the weight ratio of the extraction solvent to the feedstock is 1.5:1.

[0090] S6. The first cracked dry gas 141, the second cracked dry gas 137 and the third cracked dry gas 129 are subjected to ethane cracking treatment to obtain ethylene 149; wherein the reaction pressure is 0.10 MPa, the reaction temperature is 820℃ and the residence time is 0.25 to 0.4 s.

[0091] S7. The first cracked liquefied gas 142, the second cracked liquefied gas 138, and the third cracked liquefied gas 130 are separated into gas fractions to obtain a first stream of propylene 150, propane 135, and a C4 mixed hydrocarbon 136. The propane 135 is subjected to propane dehydrogenation to obtain a second stream of propylene 150. The C4 mixed hydrocarbon 136 is subjected to a superposition reaction to obtain superposition oil 154 and the remaining C4 hydrocarbon 155. The superposition oil 154 is returned to the third catalytic cracking in step S4. The remaining C4 hydrocarbon 155 is subjected to light hydrocarbon conversion to propane to obtain propane conversion gas 156. The propane conversion gas 156 is returned to the gas fractionation in step S7. The propane dehydrogenation reaction temperature is 600℃, the reaction pressure is 0.2MPa, the reaction time is 50h, and the propane mass hourly space velocity (MHSV) is 5h⁻¹. -1 The superposition reaction temperature was 250℃, the reaction pressure was 5MPa, and the mass hourly space velocity was 3h. -1 The reaction temperature for converting light hydrocarbons to propane is 380℃, the reaction pressure is 0.8MPa, and the mass hourly space velocity (HHSV) is 0.9h. -1 .

[0092] The products and their indicators obtained in Example 1 are listed in Table 1 below.

[0093] Under the production condition that the total crude oil processing volume is 10 million tons / year, the raw material and product indicators of the above embodiments are listed in Table 1 below:

[0094] Table 1

[0095] Example 1 carbon element amount Total crude oil volume 100 84.81％ Main product yield, % Chemicals 65.58 57.05％ ethylene 19.90 17.06％ propylene 30.35 26.01％ C6-C8 aromatics 15.33 13.98％ benzene 2.81 2.59％ Toluene 6.28 5.73％ Mixed xylene 6.24 5.65％ fuel oil 11.64 10.77％

[0096] The yield in Table 1 is a percentage obtained by dividing the weight of the product by the weight of the crude oil. The data in Table 1 shows that of the 84.81 tons of carbon contained in every 100 tons of crude oil, 57.05 tons were converted into chemical products, 10.77 tons were converted into fuel oil, and the remaining 16.99 tons were converted into flue gas after providing heat.

[0097] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the specific details of the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0098] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0099] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A crude oil processing method that maximizes the production of chemical products and also produces marine fuel, characterized in that, The method includes the following steps: S1. Separate the crude oil to obtain naphtha fraction, straight-run diesel fraction and atmospheric residue fraction; S2. Hydrogenate the atmospheric residue fraction to obtain hydrogenated diesel oil and hydrogenated heavy oil; separate a first stream of hydrogenated heavy oil and a second stream of hydrogenated heavy oil from the hydrogenated heavy oil; subject the first stream of hydrogenated heavy oil to a first catalytic cracking to obtain a first cracked dry gas, a first cracked liquefied gas, a first cracked gasoline, a first cracked diesel oil, and a cracked slurry; mix the second stream of hydrogenated heavy oil with the cracked slurry to obtain marine fuel; S3. Hydrorefining the straight-run diesel fraction and the hydrotreated residue diesel to obtain refined diesel; subjecting the refined diesel to a second catalytic cracking to obtain second cracked dry gas, second cracked liquefied gas, second cracked gasoline, and second cracked diesel. S4. The naphtha fraction and the first cracked gasoline are subjected to third catalytic cracking to obtain third cracked dry gas, third cracked liquefied gas and third cracked gasoline. S5. The first cracked diesel and the second cracked diesel are subjected to hydrocracking to obtain hydrocracking gasoline and hydrocracking diesel; the hydrocracking diesel is returned to the first catalytic cracking in step S2; the hydrocracking gasoline, the second cracked gasoline, and the third cracked gasoline are subjected to cracked gasoline hydrotreating and cracked gasoline extraction to obtain C6-C8 aromatics, raffinate, and heavy aromatics of C9 and above; the raffinate is returned to the third catalytic cracking in step S4; the heavy aromatics of C9 and above are returned to the hydrocracking in step S5. S6. The first cracked dry gas, the second cracked dry gas and the third cracked dry gas are subjected to ethane cracking treatment to obtain ethylene; S7. The first cracked liquefied gas, the second cracked liquefied gas, and the third cracked liquefied gas are separated into gas fractions to obtain a first stream of propylene, propane, and C4 mixed hydrocarbons; the propane is subjected to propane dehydrogenation to obtain a second stream of propylene; the C4 mixed hydrocarbons are subjected to a superposition reaction to obtain superposition oil and remaining C4 hydrocarbons; the superposition oil is returned to the third catalytic cracking in step S4; the remaining C4 hydrocarbons are subjected to light hydrocarbon conversion to produce propane to obtain propane conversion gas; the propane conversion gas is returned to the gas fractionation in step S7.

2. The method according to claim 1, wherein, In step S7, the gas separation also yields at least one of 1-butene, 2-butene, and butadiene.

3. The method according to claim 1, wherein, In step S1, the cut-off point between the naphtha fraction and the straight-run diesel fraction is any temperature between 175-205℃, and the cut-off point between the straight-run diesel fraction and the atmospheric residue fraction is any temperature between 335-370℃.

4. The method according to claim 1, wherein, In step S2, the reaction conditions for the hydrotreating include: a reaction temperature of 300-460℃, a reaction pressure of 6-25MPa, and a hydrogen-to-oil volume ratio of (100-1500):1; the separation point between hydrogenated diesel oil and hydrogenated heavy oil is any temperature between 335-370℃. The first catalytic cracking conditions include: a reaction temperature of 400~650℃, a reaction pressure of 0.05~1MPa, and a catalyst-to-oil weight ratio of (5-50):1; the separation point between the first cracked dry gas and the first cracked liquefied gas is any temperature between 14-16℃, the separation point between the first cracked liquefied gas and the first cracked gasoline is any temperature between 38-62℃, and the separation point between the first cracked gasoline and the first cracked diesel is any temperature between 175-205℃. The weight ratio between the first stream of hydrotreated heavy residue oil and the second stream of hydrotreated heavy residue oil is (1-15):

1.

5. The method according to claim 1, wherein, In step S3, the reaction conditions for hydrorefining include: a reaction temperature of 200-400℃, a reaction pressure of 2-16MPa, and a hydrogen-to-oil volume ratio of (400-1000):

1. The second catalytic cracking conditions include: a reaction temperature of 500~750℃, a reaction pressure of 0.05~1MPa, and a catalyst-to-oil weight ratio of (5~100):1; the separation point between the second cracked dry gas and the second cracked liquefied gas is any temperature between 14-16℃, the separation point between the second cracked liquefied gas and the second cracked gasoline is any temperature between 38-62℃, and the separation point between the second cracked gasoline and the second cracked diesel is any temperature between 175-205℃.

6. The method according to claim 5, wherein, The weight ratio of the catalyst to oil in the second catalytic cracking condition is (10~50):

1.

7. The method according to claim 1, wherein, In step S4, the third catalytic cracking conditions include: a reaction temperature of 500~750℃, a reaction pressure of 0.05~1MPa, and a catalyst-to-oil weight ratio of (5~100):1; the separation point between the third cracked dry gas and the third cracked liquefied gas is any temperature between 14-16℃, and the separation point between the third cracked liquefied gas and the third cracked gasoline is any temperature between 38-62℃.

8. The method according to claim 7, wherein, The agent-to-oil weight ratio in the third catalytic cracking condition is (10~50):

1.

9. The method according to claim 1, wherein, In step S5, the reaction conditions for hydrocracking include: a reaction temperature of 260~500℃, a hydrogen partial pressure of 3~10MPa, and a volume hourly space velocity of 0.5~6h. -1 The separation cut-off point for hydrocracked gasoline and hydrocracked diesel is any temperature between 175-205℃. The reaction conditions for the hydrotreating of the cracked gasoline include: a reaction temperature of 300-400℃ in the hydrotreating unit, a reaction pressure of 4-16MPa, and a hydrogen-to-oil volume ratio of (300-1000):

1. The conditions for the extraction of the cracked gasoline include: a temperature of 20-100℃, a pressure of 0.05-0.5MPa, and a weight ratio of extraction solvent to feedstock oil of (0.5-2.5):

1.

10. The method according to claim 1, wherein, In step S6, the reaction conditions for the ethane cracking treatment include: a reaction pressure of 0.10~0.25MPa, a reaction temperature of 810~870℃, and a residence time of 0.25~0.4s.

11. The method according to claim 1, wherein, In step S7, the reaction conditions for propane dehydrogenation include: reaction temperature 400~700℃, reaction pressure 0.05~1MPa, reaction time 40~60h, and propane mass hourly space velocity (HHSV) of 2~9h. -1 ; The reaction conditions for the superposition reaction include: a reaction temperature of 40~350℃, a reaction pressure of 0.5~10MPa, and a mass hourly space velocity of 0.2~20h. -1 The separation point between the composite oil and the remaining C4 hydrocarbons is any temperature between 30-65°C. The reaction conditions for converting light hydrocarbons to propane include: a reaction temperature of 250–550 °C, a reaction pressure of 0.1–2 MPa, and a mass hourly space velocity of 0.1–3 h⁻¹. -1 .

12. The method according to claim 11, wherein, The reaction conditions for the superposition reaction are as follows: the reaction temperature is 200-300℃.

13. A crude oil processing system that maximizes the production of chemical products and also produces marine fuel, characterized in that, The system includes: an atmospheric pressure unit, a third catalytic cracking unit, a diesel hydrorefining unit, a residue hydrorefining unit, an ethane cracking unit, a gas separation unit, a second catalytic cracking unit, a first catalytic cracking unit, a cracked gasoline hydrorefining unit, a cracked gasoline extraction unit, a catalytic diesel hydrocracking to aromatics unit, a propane dehydrogenation unit, a superposition unit, and a light hydrocarbon conversion to propane unit. The naphtha fraction outlet of the atmospheric pressure unit is connected to the third catalytic cracking inlet of the third catalytic cracking unit; the third cracked dry gas outlet of the third catalytic cracking unit is connected to the cracked dry gas inlet of the ethane cracking unit. The straight-run diesel fraction outlet of the atmospheric pressure unit is connected to the first diesel hydrorefining inlet of the diesel hydrorefining unit, and the refined diesel outlet of the diesel hydrorefining unit is connected to the refined diesel inlet of the second catalytic cracking unit. The atmospheric residue oil fraction outlet of the atmospheric pressure unit is connected to the atmospheric residue oil fraction inlet of the residue hydrotreating unit; the residue hydrotreated diesel oil outlet of the residue hydrotreating unit is connected to the second diesel hydrotreating inlet of the diesel hydrotreating unit; the first stream of residue hydrotreated heavy oil outlet of the residue hydrotreating unit is connected to the residue hydrotreated heavy oil inlet of the first catalytic cracking unit; the second stream of residue hydrotreated heavy oil outlet of the residue hydrotreating unit is connected to the cracked slurry outlet of the first catalytic cracking unit; the first cracked dry gas outlet of the first catalytic cracking unit and the second cracked dry gas outlet of the second catalytic cracking unit are respectively connected to the connecting pipelines between the third cracked dry gas outlet of the third catalytic cracking unit and the cracked dry gas inlet of the ethane cracking unit. The second liquefied petroleum gas (LPG) outlet of the second catalytic cracking unit is connected to the first LPG inlet of the gas separation unit. The third LPG outlet of the third catalytic cracking unit is connected to the connecting pipeline between the first LPG outlet of the first catalytic cracking unit and the second LPG outlet and the first LPG inlet, respectively. The third gasoline outlet of the third catalytic cracking unit is connected to the gasoline inlet of the gasoline hydrotreating unit. The second gasoline outlet of the second catalytic cracking unit is connected to the connecting pipeline between the third gasoline outlet and the gasoline inlet of the gasoline hydrotreating unit. The first gasoline outlet of the first catalytic cracking unit is connected to the third catalytic cracking inlet. The first cracked diesel outlet of the first catalytic cracking unit is connected to the first cracked diesel inlet of the catalytic diesel hydrocracking to aromatics unit; the second cracked diesel outlet of the second catalytic cracking unit is connected to the connecting pipeline between the first cracked diesel outlet and the first cracked diesel inlet; the hydrocracking gasoline outlet of the catalytic diesel hydrocracking to aromatics unit is connected to the cracked gasoline inlet of the cracked gasoline hydrotreating unit; and the hydrocracking diesel outlet of the catalytic diesel hydrocracking to aromatics unit is connected to the first catalytic cracking inlet of the first catalytic cracking unit. The propane outlet of the gas separation unit is connected to the propane inlet of the propane dehydrogenation unit, and the first propylene outlet of the gas separation unit is connected to the second propylene outlet of the propane dehydrogenation unit. The product outlet of the cracked gasoline hydrogenation unit is connected to the feed inlet of the cracked gasoline extraction unit. The residual oil outlet of the cracked gasoline extraction unit is connected to the naphtha fraction outlet and the third catalytic cracking inlet via a connecting pipeline; the heavy aromatics outlet of the cracked gasoline extraction unit is connected to the heavy aromatics inlet of the catalytic diesel hydrocracking to aromatics unit. The C4 mixed hydrocarbon outlet of the gas separation unit is connected to the C4 mixed hydrocarbon inlet of the superposition unit, and the superposition oil outlet of the superposition unit is connected to the connecting pipeline between the naphtha fraction outlet and the third catalytic cracking inlet; the remaining C4 hydrocarbon outlet of the superposition unit is connected to the remaining C4 hydrocarbon inlet of the light hydrocarbon conversion to propane unit, and the propane conversion gas outlet of the light hydrocarbon conversion to propane unit is connected to the second cracked liquefied gas inlet of the gas separation unit.

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