A method and system for upgrading heavy crude oil

Abstract

The present application relates to the technical field of petroleum refining, in particular to a heavy crude oil lightening method and system, the method comprising: pretreatment to remove ash, heavy metals and salt; atmospheric and vacuum distillation to distill naphtha, diesel and vacuum residue; vacuum residue pyrolysis to obtain pyrolysis gas, condensed oil and residue oil; secondary distillation of the condensed oil to obtain gasoline, naphtha, diesel and heavy oil, the heavy oil mixed with the residue oil to form fuel oil; each fraction desulfurized by low-temperature physical adsorption to obtain refined products; the system comprising pretreatment, main distillation, residue oil conversion, pyrolysis oil distillation and adsorption desulfurization units, the present application does not require hydrogenation, has a simple process and low investment, can efficiently treat high-sulfur, high-acid and super-heavy crude oil, has high light oil yield, standard sulfur content of products, energy self-sufficiency, energy saving and environmental protection, and is suitable for oil field site modular processing, solving the problems of large investment, easy coking and high desulfurization cost of traditional processes.

Description

Technical Field

[0001] This invention relates to the field of petroleum refining and processing technology, specifically to a method and system for lightening heavy crude oil. Background Technology

[0002] Global oil resources continue to show a trend of becoming heavier and of lower quality. There are huge reserves of heavy crude oil. This type of crude oil is characterized by low API gravity (about 8.1), high density, high viscosity, high sulfur content (about 3.94 wt%), high acid value, and extremely high content of metallic impurities (nickel, vanadium, sodium, etc.) and asphaltenes. Direct transportation and processing are extremely difficult, and traditional refining and chemical plants cannot handle it directly. At the same time, low-sulfur regulations and vehicle fuel standards are becoming increasingly stringent, requiring gasoline, diesel, and marine fuel oil to achieve deep desulfurization, which further raises the technical threshold for the lightening and refining of heavy crude oil.

[0003] Currently, the mainstream technologies for lightening heavy crude oil are hydrocracking, delayed coking, and fixed-bed catalytic cracking. Although hydrocracking yields high-quality light oil, it requires a high-pressure hydrogen-rich environment, resulting in high investment and operating costs for the supporting hydrogen production unit. Furthermore, high metal content and asphaltenes can easily lead to rapid catalyst poisoning and deactivation, resulting in short operating cycles and difficult maintenance. Delayed coking is a relatively mature process, but its liquid yield is low, and it produces a large amount of low-value-added petroleum coke as a byproduct, leading to poor resource utilization and economic benefits, as well as significant environmental pressure. Conventional catalytic cracking has poor adaptability to feedstocks and is difficult to process heavy crude oil with high metal content and high residual carbon content, resulting in severe equipment coking, low light oil yield, and excessive sulfur content in the product.

[0004] Traditional electrostatic desalting processes can only remove some salts and have limited effectiveness in removing metals and ash, failing to meet the pretreatment requirements of high-impurity heavy crude oil. Hydrodesulfurization relies on high pressure and hydrogen, resulting in high investment and safety risks, making it unsuitable for deployment in remote overseas oil fields. Existing processes generally suffer from drawbacks such as lengthy processes, high energy consumption, severe equipment corrosion, and complex waste treatment, making it difficult to simultaneously achieve the comprehensive goals of efficient impurity removal, mild conversion, deep desulfurization, and low-cost operation. In particular, it cannot meet the construction needs of small-scale, modular, and on-site direct refining.

[0005] Therefore, the industry urgently needs a non-hydrogenated, low-pressure, low-investment, and highly adaptable heavy crude oil refining technology to simultaneously solve key issues such as pretreatment and impurity removal, deep conversion of residue oil, deep desulfurization of products, energy self-sufficiency, and compliance with waste standards. This technology would enable the efficient conversion of inferior heavy crude oil into high-value-added products such as low-sulfur gasoline, diesel, and marine fuel, thereby improving resource utilization and economic benefits, meeting environmental and safety requirements, and promoting the efficient and clean utilization of heavy crude oil resources. Summary of the Invention

[0006] In order to solve the problems existing in the prior art, the present invention provides a method and system for lightening heavy crude oil, which can solve the defects of existing processes such as long process, high energy consumption, serious equipment corrosion, and complex treatment of waste.

[0007] To solve the above problems, the technical solution of the present invention is as follows: A method for lightening heavy crude oil, comprising the following steps: S1. Pretreatment: Ash removal and heavy metal removal treatment: Mix heavy crude oil with deashing agent or separating agent, and remove salt, heavy metals and ash by separation to obtain deashed crude oil; after the removal of ash, salt and heavy metals, the content of harmful components can be less than 0.03%.

[0008] S2. The deashed crude oil is heated in a heating furnace and subjected to atmospheric and vacuum fractionation to separate naphtha components, diesel components and vacuum residue. S3. The vacuum residue obtained in S2 is subjected to thermal cracking to obtain pyrolysis gas, pyrolysis condensate, and pyrolysis residue. S4. Pyrolysis oil fractionation: The pyrolysis condensate obtained in S3 is fractionated under atmospheric pressure to obtain gasoline, naphtha, and light diesel oil components. The bottom oil is then fractionated under reduced pressure to obtain diesel oil and heavy oil. The heavy oil is mixed with pyrolysis residue oil to obtain fuel oil. S5. Desulfurization and refining treatment: The naphtha and diesel components obtained in S2, as well as the gasoline, naphtha, light diesel, and diesel obtained in S4, are heated separately and then the organic sulfur is removed by physical adsorption in the desulfurization adsorption tower to obtain refined products.

[0009] Furthermore, in S1, the heavy crude oil has an API gravity of 7.5-8.7, a density of 1.011-1.016 g / cm³, a sulfur content of 3.78-4.10 wt%, an acid value of 3.0-4.2 mg KOH / g, a nickel content of 92-104 ppm, and a vanadium content of 399-431 ppm.

[0010] Furthermore, in S1, the mixing temperature is 145-155℃, the separation method is centrifugal separation, and the deashing agent is a physical adsorption type deashing agent with an efficiency of not less than 99% in removing salt, metal and ash.

[0011] Furthermore, in S2, the top temperature of the atmospheric distillation column is 100-200℃, which cuts out naphtha components at 0-150℃ and diesel components at 150-370℃. The absolute pressure at the top of the vacuum distillation column is not lower than -0.1 MPa, and fuel oil components with a temperature range of 370-520℃ are cut off. The vacuum residue oil obtained at the bottom of the column has a distillation range of above 520℃.

[0012] Furthermore, in S3, the thermal cracking reaction temperature is 480-530℃, and the resulting pyrolysis gas enters the fluidized bed catalytic reactor for catalytic cracking under the action of a catalyst.

[0013] Furthermore, the pyrolysis gas obtained in S3 is cooled and separated to obtain non-condensable gas, which, together with the non-condensable gas generated at the top of the vacuum distillation tower in S2, is collected and used as fuel gas for the heating furnace.

[0014] Furthermore, in S4, the gasoline fraction is produced at the top of the atmospheric distillation column of the pyrolysis condensate, and the naphtha and light diesel fractions are produced on the side stream. The side stream of the vacuum distillation produces diesel fraction, and the heavy oil obtained from the bottom of the tower is mixed with the pyrolysis residue oil obtained from S3.

[0015] Furthermore, in S5, the operating temperature for physical adsorption to remove organic sulfur is 75-85℃, and the desulfurization adsorption towers are configured in parallel with at least two towers, operating in a mode where one tower adsorbs while the other tower regenerates or is on standby.

[0016] Furthermore, in S5, the regeneration of the desulfurization adsorption tower includes: introducing a regeneration liquid containing an oxidant into the saturated adsorption tower to convert the adsorbed organic sulfur into water-soluble inorganic sulfides, and sending the regeneration waste liquid to the sewage treatment system.

[0017] The system using the aforementioned method for lightening heavy crude oil includes the following units connected in sequence: The pretreatment unit, including a mixing tank and a centrifugal separator, is used to mix and separate heavy crude oil with a deashing agent or a separating agent to remove salt, metals and ash, and obtain deashed crude oil. The main fractionation unit, including an atmospheric distillation tower, a vacuum distillation tower, and a matching heating furnace and heat exchange network, is connected to the pretreatment unit and is used to perform atmospheric and vacuum fractionation on the deashed crude oil to obtain naphtha components, diesel components, and vacuum residue. The residue conversion unit includes a pyrolysis reaction chamber and a fluidized bed catalytic reactor, which are connected to the main fractionation unit and are used to perform thermal cracking reaction on the vacuum residue to obtain pyrolysis gas, pyrolysis condensate and pyrolysis residue. The pyrolysis oil fractionation unit includes an atmospheric pyrolysis oil fractionation tower and a vacuum pyrolysis oil fractionation tower, which are connected to the residue oil conversion unit. It is used to fractionate the pyrolysis condensate to obtain gasoline, naphtha, light diesel oil components, diesel oil and heavy oil. The heavy oil discharge line is merged with the pyrolysis residue oil discharge line for mixing to obtain fuel oil. The adsorption desulfurization unit includes at least two desulfurization adsorption towers connected in parallel and switchable, which are respectively connected to the main fractionation unit and the pyrolysis oil fractionation unit. They are used to receive and perform physical adsorption desulfurization on naphtha and diesel components from the main fractionation unit, as well as gasoline, naphtha, light diesel and diesel from the pyrolysis oil fractionation unit, to obtain refined products.

[0018] Compared with existing technologies, this invention has the following advantages: It adopts a non-hydrogenation process route of physical adsorption deashing - atmospheric and vacuum distillation - pyrolysis catalysis - pyrolysis oil fractionation - physical adsorption desulfurization, which avoids the dependence of traditional hydrocracking on high-pressure hydrogen-containing environments and expensive hydrogen production equipment. It solves the technical bottleneck that heavy crude oil with high metal content and high asphaltene content can easily lead to rapid poisoning and deactivation of hydrogenation catalysts. The investment cost is reduced by 30% to 40%, and the operating risk is significantly reduced. It is particularly suitable for deployment in remote overseas oil fields where hydrogen sources are scarce.

[0019] Using a physical adsorption type deashing agent, the deashing agent or separating agent is mixed with heavy crude oil in a mixing tank and then centrifuged to simultaneously remove salt, metals and ash from the crude oil. The removal efficiency reaches over 99%, which breaks through the technical limitations of traditional electrostatic desalting processes that can only remove part of the salt, cannot handle high-salt-content heavy crude oil, and cannot simultaneously remove metals and ash. This effectively protects downstream equipment from corrosion and scaling and extends the operating cycle of the unit.

[0020] The vacuum residue (accounting for 58.66% of crude oil) is subjected to thermal cracking at 480-530℃, and a fluidized bed catalytic reactor is set up for catalytic cracking assistance. The low-value-added residue components are efficiently converted into light oil products such as gasoline, naphtha, and diesel. The total yield of light oil in a single unit reaches 78.24% (gasoline 13.40%, naphtha 6.71%, diesel 58.13%), which is 15-20 percentage points higher than the liquid yield of delayed coking process, and the resource utilization rate is significantly improved.

[0021] The pyrolysis condensate is returned to the pyrolysis oil fractionation unit for further fractionation. After heat exchange with the crude oil side stream material, it enters the atmospheric and vacuum distillation towers of the pyrolysis oil, separating gasoline, naphtha, light diesel oil, and diesel oil. The heavy oil at the bottom of the tower is mixed with the pyrolysis residue oil as fuel oil product, forming a material circulation network of pyrolysis-fractionation-refractionation. This achieves cascade utilization of thermal energy and maximizes material recovery, reduces the heat load of the heating furnace, and reduces the overall energy consumption by 10%-15% compared with the traditional process.

[0022] Two desulfurization adsorption towers are set up in parallel, with one tower adsorbing while the other is regenerated online or on standby, and switching operations enable continuous production. The desulfurization temperature is controlled at 75-85℃, which is much lower than the 300-400℃ operating temperature of hydrodesulfurization. After the adsorbent is saturated, it is regenerated with an oxidant, and the organic sulfur is converted into inorganic sulfides that dissolve in water. The precipitate is obtained by calcium oxide treatment or by reverse osmosis concentration and multi-effect evaporation to obtain sodium sulfate solid. This realizes the recycling of desulfurizing agent and the resource recovery of sulfur element. The consumption of desulfurizing agent is extremely small, and the operating cost is greatly reduced. Attached Figure Description

[0023] Figure 1 This is a process flow diagram of the S1 process of the present invention; Figure 2 This is a flow chart of the atmospheric distillation process in S2 of the present invention; Figure 3 This is a flow chart of the vacuum distillation process in S2 of the present invention; Figure 4 This is a process flow diagram of the S3 pyrolysis reaction chamber and fluidized bed catalytic reactor of the present invention; Figure 5 This is a flow chart of the atmospheric pressure fractionation process for S4 pyrolysis oil according to the present invention; Figure 6 This is a flow chart of the vacuum fractionation process for S4 pyrolysis oil according to the present invention; Figure 7 This is a process flow diagram for the S5 process of the present invention; Figure 8 This is a system block diagram of the present invention. Detailed Implementation

[0024] This invention discloses a system for a method of lightening heavy crude oil, such as... Figure 8 As shown, it includes the following units connected in sequence: The pretreatment unit, including a mixing tank and a centrifugal separator, is used to mix and separate heavy crude oil with a deashing agent or a separating agent to remove salt, metals and ash, and obtain deashed crude oil. The main fractionation unit, including an atmospheric distillation tower, a vacuum distillation tower, and a matching heating furnace and heat exchange network, is connected to the pretreatment unit and is used to perform atmospheric and vacuum fractionation on the deashed crude oil to obtain naphtha components, diesel components, and vacuum residue. The residue conversion unit includes a pyrolysis reaction chamber and a fluidized bed catalytic reactor, which are connected to the main fractionation unit and are used to perform thermal cracking reaction on the vacuum residue to obtain pyrolysis gas, pyrolysis condensate and pyrolysis residue. The pyrolysis oil fractionation unit includes an atmospheric pyrolysis oil fractionation tower and a vacuum pyrolysis oil fractionation tower, which are connected to the residue oil conversion unit. It is used to fractionate the pyrolysis condensate to obtain gasoline, naphtha, light diesel oil components, diesel oil and heavy oil. The heavy oil discharge line is merged with the pyrolysis residue oil discharge line for mixing to obtain fuel oil. The adsorption desulfurization unit includes at least two desulfurization adsorption towers connected in parallel and switchable, which are respectively connected to the main fractionation unit and the pyrolysis oil fractionation unit. They are used to receive and perform physical adsorption desulfurization on naphtha and diesel components from the main fractionation unit, as well as gasoline, naphtha, light diesel and diesel from the pyrolysis oil fractionation unit, to obtain refined products.

[0025] The heavy crude oil described in this application is an extra-heavy, high-sulfur, high-acid, and high-metal-content naphthenic crude oil with an API gravity of 7.5-8.7, a density of 1.011-1.016 g / cm³, a sulfur content of 3.78-4.10 wt%, an acid value of 3.0-4.2 mg KOH / g, a nickel content of 92-104 ppm, and a vanadium content of 399-431 ppm. This heavy crude oil is 84.56% AR370+ residue oil component and 58.66% VR520+ vacuum residue oil, making it extremely difficult to process using conventional methods.

[0026] The detailed process steps of the system using the non-hydrogenation method for lightening heavy crude oil are as follows: S1. Pretreatment (ash removal, metal removal) Process flow as follows Figure 1 As shown, the above-mentioned heavy crude oil and physical adsorption deashing agent are mixed in a mixing tank (Φ6600×10000mm, Q245R, 2 units in parallel) at 145~155℃, and then separated and removed from salt, metal and ash by centrifuges (4 sets), with a removal efficiency of ≥99%; the deashed crude oil is then buffered in a buffer tank (Φ6600×10000mm, Q245R). The main consumption of the pretreatment unit is: 1500t / a of deashing agent and 16000t / a of caustic soda flakes. After the removal of ash, salt and heavy metals, the content of harmful components can be less than 0.03%.

[0027] S2, Atmospheric and vacuum distillation Process flow as follows Figure 2 , 3As shown, the deashed crude oil is heated to 340~360℃ by heat exchange with the materials from the atmospheric distillation line 1, atmospheric distillation line 2, vacuum distillation line 1, vacuum distillation line 2, and the bottom material of the vacuum distillation tower via a heat exchange network. It then enters the atmospheric distillation tower (Φ1400×25500mm, 48 trays, Q345R+S304L+316L, operating temperature 360-380℃, slightly positive pressure). Naphtha (distillation range 19-150℃) is obtained at the top of the tower, and diesel oil is obtained from the side line 1 and side line 2. After being pressurized by the bottom oil pump, it is sent to the vacuum distillation furnace for heating to 360~380℃ and then enters the vacuum distillation tower (Φ1400 / Φ2400 / Φ1600×30400mm, packing + trays, 0.3 / -0.1MPa, 370~390℃). Diesel oil is obtained from the side stream, and vacuum residue is obtained from the bottom of the tower.

[0028] The diesel components are sent to the diesel component tank after heat exchange with crude oil and water cooling to 40°C. The non-condensable gas at the top of the vacuum tower is condensed in two stages. The condensate is sent to the diesel component tank, while the non-condensable gas is pressurized by a vacuum pump and used as fuel for the heating furnace.

[0029] S3, pyrolysis catalyst Process flow as follows Figure 4 As shown, vacuum residue is fed into the pyrolysis reaction chamber (horizontal double-layer cylindrical furnace, 310S material, 6 sets), where hot air is used as the heat carrier for thermal cracking at 480~530℃. Scrapers are installed in the inner cylinder to prevent coking on the inner wall, and coking is periodically cleaned online. The cleaned coke is mixed with the residue and exits the pyrolysis furnace. The pyrolysis gas enters the fluidized bed catalytic reactor (Φ3000×8000mm, 316L, 2 units), where it undergoes further cracking under the action of the catalytic cracking catalyst.

[0030] The pyrolysis gas (2529.75 kg / h, approximately 1300 Nm³ / h) exchanges heat with the fractionation side stream material in a heat exchanger, and then is condensed in a condenser. The condensed oil enters the pyrolysis oil separator, while the non-condensable gas goes to the fuel gas buffer tank as fuel for the heating furnace. The pyrolysis residue oil is pressurized by a pump and then cooled to 150°C in a cooling water tank (heat exchange area 100 m²) before being stored in the tank area. The pyrolysis catalytic unit mainly consumes 100 t / a of catalyst.

[0031] S4, Pyrolysis Oil Fractionation Process flow as follows Figure 5 , 6As shown, the pyrolysis condensate first exchanges heat with the side stream of the fractionation tower and then enters the atmospheric pyrolysis oil tower (Φ1200×25500mm, Q345R+S304L+316L, 350-370℃). Gasoline and naphtha are separated from the top of the tower, and light diesel oil is separated from the side stream. The bottom oil is pressurized by a pump and heated to 350-370℃ in the pyrolysis oil vacuum furnace before entering the pyrolysis oil vacuum tower (Φ1200 / Φ1800 / Φ1400×30400mm, Q345R+S304L+316L, 0.3 / -0.1MPa). Diesel oil is separated from the side stream, and heavy oil is obtained from the bottom of the tower. The heavy oil is mixed with the pyrolysis residue oil obtained from S3 to obtain fuel oil.

[0032] S5, Desulfurization and Refining Process flow as follows Figure 7 As shown, the naphtha and diesel oil obtained from S2, and the gasoline, naphtha, light diesel oil, and diesel oil obtained from S4 are pressurized by pumps, heated to 80°C after heat exchange with the desulfurized effluent, and then enter the desulfurization adsorption towers (two units, one for adsorption and one for regeneration, switching between them as backups). Organic sulfur is removed under the action of physical adsorbents. After the adsorbents are saturated, they are regenerated using an oxidant, converting the organic sulfur into inorganic sulfides that dissolve in water. The regenerated wastewater is sent to the wastewater treatment system, where calcium oxide treatment yields calcium sulfate precipitate. The sodium hydroxide solution is recycled, or concentrated using reverse osmosis followed by multi-effect evaporation to obtain solid sodium sulfate. The main consumption of the desulfurization refining unit is 50t / 2a of desulfurizing agent. When the desulfurizing agent is saturated, a reducing agent is added for further online reduction, allowing for repeated use with a service life of over two years, significantly reducing production costs.

[0033] The material balance is shown in Table 1 below. Table 1 Material Balance Sheet for the Unit (Single Unit 300,000 tons / year)

[0034] The dry gas includes vacuum gas and pyrolysis gas, with a single unit output of approximately 1300 Nm³ / h and a total output of 2600 Nm³ / h for both units. The production unit uses 1400 Nm³ / h, the CPF steam boiler uses 500 Nm³ / h, and the surplus 700 Nm³ / h is used as fuel for gas-fired power generation.

[0035] The product quality indicators are shown in Table 2 below. Table 2. Main Product Property Data Table

[0036] Public works consumption is shown in Table 3 below. Table 3. Consumption of Public Utilities (300,000 tons / year per unit)

[0037] The main equipment selection is shown in Table 4 below. Table 4. List of Key Equipment (Single Set)

[0038] Project Implementation and Economic Benefits This project is a new project with a total construction period of 12 months, including 10 months for design and procurement, 10 months for construction, and 1 month for commissioning. The main technical and economic indicators are shown in Table 5 below.

[0039] Table 5. Main Technical and Economic Indicators

[0040] The waste treatment measures of this project meet the requirements of green and environmentally friendly chemical production. Wastewater: Sulfur-containing wastewater is treated with calcium oxide to obtain calcium sulfate precipitate after oil separation and buffering, or concentrated by reverse osmosis and then evaporated by multi-effect evaporation to obtain sodium sulfate solid; the wastewater treatment plant has a treatment capacity of 150t / d, and the effluent COD ≤ 120mg / L and petroleum ≤ 15mg / L.

[0041] Exhaust gas: Pyrolysis gas and non-condensable gas from the top of the pressure reducing tower are all collected and used as fuel for the heating furnace. The surplus is used for power generation, achieving closed-loop emission. The device is equipped with a self-protection system and a combustible gas alarm.

[0042] Solid waste: Deashing slag (approximately 3000 t / a) and waste adsorbent (30 t / 2a) are sent to the solid waste treatment center and incinerated in a converter for use as building materials. The above specific embodiments are only used to illustrate the technical solution of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solution of the present invention without departing from the scope of the technical solution of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for lightening heavy crude oil, characterized in that, Includes the following steps: S1. Pretreatment, including deashing and heavy metal removal: Heavy crude oil is mixed with a deashing agent or separating agent, and then separated to remove salt, heavy metals and ash to obtain deashed crude oil; S2. The deashed crude oil is heated in a heating furnace and subjected to atmospheric and vacuum fractionation to separate naphtha components, diesel components and vacuum residue. S3. The vacuum residue obtained in S2 is subjected to thermal cracking to obtain pyrolysis gas, pyrolysis condensate, and pyrolysis residue. S4. Pyrolysis oil fractionation: The pyrolysis condensate obtained in S3 is fractionated under atmospheric pressure to obtain gasoline, naphtha, and light diesel oil components. The bottom oil is then fractionated under reduced pressure to obtain diesel oil and heavy oil. The heavy oil is mixed with pyrolysis residue oil to obtain fuel oil. S5. Desulfurization and refining treatment: The naphtha and diesel components obtained in S2, as well as the gasoline, naphtha, light diesel, and diesel obtained in S4, are heated separately and then the organic sulfur is removed by physical adsorption in the desulfurization adsorption tower to obtain refined products.

2. The method for lightening heavy crude oil according to claim 1, characterized in that: In S1, the heavy crude oil has an API gravity of 7.5-8.7, a density of 1.011-1.016 g / cm³, a sulfur content of 3.78-4.10 wt%, an acid value of 3.0-4.2 mg KOH / g, a nickel content of 92-104 ppm, and a vanadium content of 399-431 ppm.

3. The method for lightening heavy crude oil according to claim 2, characterized in that: In S1, the mixing temperature is 145-155℃, the separation method is centrifugal separation, and the deashing agent is a physical adsorption type deashing agent with an efficiency of not less than 99% in removing salt, metal and ash.

4. The method for lightening heavy crude oil according to claim 3, characterized in that: In S2, the top temperature of the atmospheric distillation column is 100-200℃, which cuts out naphtha components at 0-150℃ and diesel components at 150-370℃. The absolute pressure at the top of the vacuum distillation column is not lower than -0.1 MPa, and fuel oil components with a temperature range of 370-520℃ are cut off. The vacuum residue oil obtained at the bottom of the column has a distillation range of above 520℃.

5. The method for lightening heavy crude oil according to claim 4, characterized in that: In S3, the thermal cracking reaction temperature is 480-530℃, and the resulting pyrolysis gas enters the fluidized bed catalytic reactor for catalytic cracking under the action of a catalyst.

6. The method for lightening heavy crude oil according to claim 5, characterized in that: The pyrolysis gas obtained in S3 is cooled and separated to obtain non-condensable gas, which, together with the non-condensable gas produced at the top of the vacuum distillation tower in S2, is collected and used as fuel gas for the heating furnace.

7. The method for lightening heavy crude oil according to claim 6, characterized in that: In S4, the gasoline fraction is produced at the top of the atmospheric distillation tower of the pyrolysis condensate, and the naphtha and light diesel fractions are produced on the side stream. The side stream of the vacuum distillation produces diesel fraction, and the heavy oil obtained from the bottom of the tower is mixed with the pyrolysis residue oil obtained from S3.

8. The method for lightening heavy crude oil according to claim 7, characterized in that: In S5, the operating temperature for physical adsorption to remove organic sulfur is 75-85℃. The desulfurization adsorption towers are configured with at least two in parallel, and the operating mode is one tower adsorbs while the other tower regenerates or is on standby.

9. A method for lightening heavy crude oil according to claim 8, characterized in that: In S5, the regeneration of the desulfurization adsorption tower includes: introducing a regeneration liquid containing an oxidant into the saturated adsorption tower to convert the adsorbed organic sulfur into water-soluble inorganic sulfides, and sending the regeneration waste liquid to the sewage treatment system.

10. A system using the method for lightening heavy crude oil according to any one of claims 1-9, characterized in that, Includes the following units connected in sequence: The pretreatment unit, including a mixing tank and a centrifugal separator, is used to mix and separate heavy crude oil with a deashing agent or a separating agent to remove salt, metals and ash, and obtain deashed crude oil. The main fractionation unit, including an atmospheric distillation tower, a vacuum distillation tower, and a matching heating furnace and heat exchange network, is connected to the pretreatment unit and is used to perform atmospheric and vacuum fractionation on the deashed crude oil to obtain naphtha components, diesel components, and vacuum residue. The residue conversion unit includes a pyrolysis reaction chamber and a fluidized bed catalytic reactor, which are connected to the main fractionation unit and are used to perform thermal cracking reaction on the vacuum residue to obtain pyrolysis gas, pyrolysis condensate and pyrolysis residue. The pyrolysis oil fractionation unit includes an atmospheric pyrolysis oil fractionation tower and a vacuum pyrolysis oil fractionation tower, which are connected to the residue oil conversion unit. It is used to fractionate the pyrolysis condensate to obtain gasoline, naphtha, light diesel oil components, diesel oil and heavy oil. The heavy oil discharge line is merged with the pyrolysis residue oil discharge line for mixing to obtain fuel oil. The adsorption desulfurization unit includes at least two desulfurization adsorption towers connected in parallel and switchable, which are respectively connected to the main fractionation unit and the pyrolysis oil fractionation unit. They are used to receive and perform physical adsorption desulfurization on naphtha and diesel components from the main fractionation unit, as well as gasoline, naphtha, light diesel and diesel from the pyrolysis oil fractionation unit, to obtain refined products.

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