A method for processing residual oil

Abstract

This invention provides a method for processing residual oil, comprising the following steps: Residual oil feedstock, alkali metal, and hydrogen are mixed and then introduced into an alkali metal treatment reaction zone for reaction. The alkali metal treatment reaction zone includes two or more alkali metal treatment reactors connected in series. When the sulfur content of the outlet material of any alkali metal treatment reactor in the alkali metal treatment reaction zone decreases to 15%–70%, preferably 25%–60%, of the sulfur content of the inlet material, the material from that alkali metal treatment reactor enters a downstream alkali metal treatment reactor connected in series. This process continues until the properties of the outlet material from the alkali metal treatment reactor meet the requirements: sulfur content not exceeding 0.5 wt%, and metal content not exceeding 10 ppm. This method uses alkali metals to treat inferior residual oil, achieving efficient removal of sulfur and metal impurities from the residual oil.

Description

Technical Field

[0001] This invention belongs to the field of oil refining and chemical engineering, and specifically relates to a method for processing residual oil, particularly a method for processing high-sulfur, low-quality residual oil. Background Technology

[0002] Crude oil can be distilled at atmospheric pressure and by vacuum distillation to obtain atmospheric residue and vacuum residue, respectively. In most important oilfields in my country, vacuum residue content is relatively high, with a yield of 40%–50% for vacuum residue distilled at temperatures above 500°C. How to fully utilize and rationally process this heavy component is one of the important issues in the petroleum refining industry. However, vacuum residue contains the components with the largest relative molecular mass, highest boiling point, highest heteroatom content, and most complex structure in crude oil. Converting the residue into directly usable fuel oil or chemical products, and effectively removing impurities such as sulfur, nitrogen, metals, and asphaltenes, is a key step in petroleum refining and chemical processing.

[0003] Effective January 1, 2020, the global standard for sulfur content in marine fuel oil was adjusted to 0.5 wt%, making the production of low-sulfur marine fuel an important direction for the refining industry and major refineries in adjusting their product structure. Similarly, the quality of globally processed oil products is deteriorating, and more efficient heavy oil impurity removal processes remain a key technological requirement for the refining and petrochemical industries. Industrially, hydrodesulfurization (HDS) technology is widely used to reduce the sulfur content of residue oil. HDS technology mainly includes fixed-bed and fluidized-bed residue oil hydrotreating technologies. Traditional HDS technology has advantages such as high oil yield, good technical and economic efficiency, and the ability to simultaneously remove nitrogen, oxygen, and metals, as well as control olefin and aromatic hydrocarbon content. However, the reaction needs to be carried out under high temperature and pressure, and the desulfurization of thiophene aromatic compounds is difficult and inefficient. In deep desulfurization processes, excessive hydrogenation of olefins and aromatic hydrocarbons can occur, reducing fuel oil quality. At the same time, traditional desulfurization processes also have disadvantages such as high investment costs, short equipment operating cycles, and poor feedstock adaptability.

[0004] CN113578337A discloses a residue oil hydrotreating catalyst, its preparation method, and its application. By molding and pulverizing magnesium oxide and alumina, a catalyst support with a directionally arranged pore structure is obtained, optimizing the catalyst support and improving its demetallization and anti-carbon deposition capabilities. Acid treatment expands the specific surface area of ​​the support, increasing the number of acidic centers and providing more active sites for hydrotreating performance. Adding a penetrant during catalyst impregnation allows for a more uniform distribution of the active metal on the support, improving the desulfurization and denitrification performance of residue oil hydrotreating while reducing the mass of the active metal.

[0005] CN1324692A discloses a method for extending the service life of a catalyst. The method involves switching the residue oil feedstock to distillate oil containing a sulfiding agent into the catalyst bed during normal operation of the residue oil catalyst without stopping the operation. After sulfidation, the feedstock is then switched back to normal heavy and residue oil to extend the service life of the residue oil catalyst.

[0006] CN114214088A discloses a process and apparatus for extending the hydrogenation reaction cycle of residual oil. Residual oil and hydrogen are sequentially injected into a hydrogenation protection reactor, a hydrogenation demetallization reactor, and a hydrogenation desulfurization reactor for hydrogenation reactions. An upward flow occurs in the hydrogenation protection reactor, while a downward flow occurs in the demetallization and desulfurization reactors. The hydrogenation product discharged from the desulfurization reactor undergoes gas-liquid separation to obtain a liquid phase and a gas phase. The gas phase, after impurity removal, becomes circulating hydrogen, which is then circulated back into the demetallization and desulfurization reactors to participate in the reaction. The hydrogenation protection reactor is equipped with a combination of a bubbler and a fractal bubble generator for hydrogenation, improving the mass transfer coefficient and reaction efficiency of the hydrogenation reaction. The introduction of circulating hydrogen reduces the temperature and pressure differences in the catalyst bed, mitigating problems such as coking, blockage, and excessive pressure drop.

[0007] The technical solutions of the aforementioned patents have very limited effects in reducing pressure drop, delaying the occurrence of hot spots, and improving fluid distribution, and cannot fundamentally avoid the occurrence of pressure drop and hot spot problems. Summary of the Invention

[0008] Through in-depth research, the inventors discovered that while alkali metal desulfurization technology can effectively avoid pressure drop and hot spot issues, it suffers from problems such as easy carbon buildup, coking, and low liquid yield when processing high-sulfur feedstocks, especially high-thiophene sulfides. The reasons are as follows: Under high-temperature conditions, when the quality ratio of alkali metal to residual oil feedstock is high, a large amount of coke is generated in the reaction system. Sulfur-containing compounds in the residual oil, especially thiophene sulfides, react with alkali metals to form intermediate species that are bonded to organic matter. These intermediate species are prone to condensation reactions, ultimately producing coke. The higher the concentration of these intermediate products in the reaction system, the faster the condensation and coking reaction rate. Therefore, adjusting the conversion depth of sulfur-containing compounds in the reactor, especially the conversion depth of thiophene sulfides, can effectively control the concentration of intermediate species in the reaction system, thereby reducing the occurrence of side reactions such as coking and improving liquid yield.

[0009] To address the shortcomings of existing technologies, the inventors, based on the theoretical foundation of their research, provide a method for processing residual oil. This method enables efficient alkali metal treatment of inferior residual oil with high sulfur content, especially high thiophene sulfur content. The method can reduce coking reaction and improve liquid phase yield.

[0010] A method for processing residual oil includes the following steps: residual oil feedstock, alkali metal, and hydrogen are mixed and then fed into an alkali metal treatment reaction zone for reaction. The alkali metal treatment reaction zone includes two or more alkali metal treatment reactors connected in series. When the sulfur content of the outlet material of any alkali metal treatment reactor in the alkali metal treatment reaction zone decreases to 15% to 70%, preferably 25% to 60%, of the sulfur content of the inlet material, the material from that alkali metal treatment reactor enters a downstream alkali metal treatment reactor connected in series. This process continues until the properties of the outlet material of the alkali metal treatment reactor meet the requirements: sulfur content not greater than 0.5 wt%, and metal content not greater than 10 ppm.

[0011] Furthermore, in the residue oil processing method of the present invention, when the sulfur content of the outlet material of any alkali metal processing reactor in the alkali metal processing reaction zone decreases to 15% to 70% of the sulfur content of the inlet material, and at the same time the thiophene sulfide content in the outlet material decreases to 20% to 60% of the thiophene sulfide content in the inlet material, preferably when the sulfur content of the outlet material decreases to 25% to 60% of the sulfur content of the inlet material, and at the same time the thiophene sulfide content in the outlet material decreases to 25% to 55% of the thiophene sulfide content in the inlet material, the material of the alkali metal processing reactor enters the downstream alkali metal processing reactor arranged in series.

[0012] Furthermore, in the residue hydrotreating method of the present invention, the alkali metal treatment reaction zone includes two or more alkali metal treatment reactors connected in series, preferably including 3 to 8 alkali metal treatment reactors connected in series, and more preferably including 3 or 4 alkali metal treatment reactors connected in series.

[0013] Furthermore, in the residue oil processing method of the present invention, the sulfur content of the outlet material of any alkali metal processing reactor in the alkali metal processing reaction zone is reduced to 15% to 70% of the sulfur content of the inlet material by setting the process conditions, and the thiophene sulfide content in the outlet material is reduced to 20% to 60% of the thiophene sulfide content in the inlet material.

[0014] Furthermore, in the residue oil processing method of the present invention, when the alkali metal treatment reactors connected in series in the alkali metal treatment reaction zone adopt different feed ratios, the mass ratio of alkali metal to reactor inlet material in two adjacent alkali metal treatment reactors is controlled. The mass ratio of alkali metal to reactor inlet material in the downstream alkali metal treatment reactor is 20% to 55% lower than that in the upstream alkali metal treatment reactor, preferably 30% to 45%.

[0015] Furthermore, in the residue oil processing method of the present invention, when the various alkali metal treatment reactors connected in series in the alkali metal treatment reaction zone adopt different operating conditions, the operating temperature difference between two adjacent alkali metal treatment reactors is controlled to be 5-15℃, preferably 8-10℃.

[0016] Furthermore, in the residue oil processing method of the present invention, the outlet material of at least one alkali metal treatment reactor in the alkali metal treatment reaction zone is divided into two streams of material, namely a first liquid phase material and a second liquid phase material; the first liquid phase material is circulated to any one of the alkali metal treatment reactors, and the second liquid phase material enters a downstream alkali metal treatment reactor arranged in series; the mass ratio of the first liquid phase material to the second liquid phase material is 0.2-1.5, preferably 0.4-0.8.

[0017] Furthermore, in the residue oil processing method of the present invention, the alkali metal is at least one of Li, Na and K, preferably Na.

[0018] Furthermore, in the residual oil processing method of the present invention, the mass ratio of the alkali metal to the reactor inlet material is 0.02-0.15, preferably 0.03-0.07.

[0019] Furthermore, in the residual oil processing method of the present invention, the alkali metal treatment reactor is one or more of the following: intermittent high-pressure reactor, CSTR reactor, and pipeline reactor, preferably a pipeline reactor.

[0020] Furthermore, in the residue oil processing method of the present invention, part or all of the inlet material of the alkali metal treatment reactor is premixed with alkali metal in a mixer to obtain a highly dispersed liquid alkali metal mixture, which is then mixed with hydrogen and enters the alkali metal treatment reactor for reaction.

[0021] Furthermore, in the residue oil processing method of the present invention, the mixing temperature is 95-150℃, preferably 100-120℃; the mixing time is 3-10 min, preferably 5-8 min.

[0022] Furthermore, in the residue oil processing method of the present invention, the size distribution range of the liquid alkali metal in the highly dispersed liquid alkali metal mixture is 15-85 μm, preferably 20-35 μm.

[0023] Furthermore, in the residue oil processing method of the present invention, the mixer can be an emulsification mixing tank, in which an agitator is installed to achieve a high degree of mixing between the alkali metal and the oil phase.

[0024] Furthermore, in the residue oil processing method of the present invention, the reaction conditions are as follows: hydrogen pressure of 2-10 MPa, reaction temperature of 240-380℃, hydrogen-to-oil volume ratio of 100-400, and reaction residence time of 5-30 min; preferably, hydrogen pressure of 3-6 MPa, reaction temperature of 290-340℃, hydrogen-to-oil volume ratio of 200-300, and reaction residence time of 10-20 min.

[0025] Furthermore, in the residue oil processing method of the present invention, the residue oil feedstock can be one or more of atmospheric residue oil and vacuum residue oil, and typically also contains one or more of straight-run wax oil, vacuum wax oil, and catalytic recycle oil. The residue oil feedstock has a sulfur content of 3.5-7.0 wt%, a thiophene sulfide content of 1.8-4.5 wt%, and a metal content of 120-260 ppm; preferably, the sulfur content is 4.0-6.0 wt%, the thiophene sulfide content is 2.6-3.8 wt%, and the metal content is 160-240 ppm.

[0026] The advantages of this invention are:

[0027] This invention optimizes the alkali metal treatment process, enabling staged reactions between sulfur-containing compounds and alkali metals in feedstock oil. Particularly for thiophene sulfides, which are difficult to remove, the staged reaction controls the conversion depth of thiophene sulfides, effectively avoiding side reactions caused by excessive alkali metal addition at once, while achieving deep and efficient desulfurization.

[0028] The effluent from the upstream reactor is used as raw material to enter the downstream reactor. The effluent contains alkali metal sulfides, which can serve as growth centers for solid products after entering the downstream reactor, thus facilitating solid-liquid separation of the final reaction material.

[0029] The effluent from the alkali metal treatment reactor is partially recycled to any upstream alkali metal treatment reactor. This recycled oil serves as an intermediate medium, promoting the emulsification and dispersion of liquid alkali metals in the oil phase. Simultaneously, this recycled oil dilutes the feedstock entering the alkali metal treatment reactor, reducing the system viscosity and enhancing the alkali metal impurity removal reaction. Attached Figure Description

[0030] Figure 1 This is a process flow for processing residual oil.

[0031] Wherein, 1 is residual oil feedstock; 2 is hydrogen; 3 is emulsifying mixing tank; 4 is feed to the first reactor; 5 is the first reactor; 6 is discharge from the first reactor; 7 is emulsifying mixing tank; 8 is feed to the second reactor; 9 is the second reactor; 10 is the second liquid phase material of the second reactor; 11 is emulsifying mixing tank; 12 is feed to the third reactor; 13 is the third reactor; 14 is residual oil desulfurization product; 15 is the first liquid phase material of the second reactor; and 16 is an alkali metal tank.

[0032] Figure 2 This refers to the large amount of coking byproducts generated during the experiment of Comparative Example 1. Implementation

[0033] The method provided by the present invention will now be described with reference to the accompanying drawings.

[0034] The residue oil feedstock 1, the first liquid phase material 15 from the second reactor, the alkali metal from the alkali metal tank 16, and hydrogen 2 are all mixed together in the emulsion mixing tank 3. After mixing, the material 4 enters the first reactor 5 for the first reaction. Then, the discharge 6 from the first reactor enters the emulsion mixing tank 7 and is mixed again with the alkali metal from the alkali metal tank 16. The mixed feedstock 8 from the second reactor enters the second reactor 9 for the second reaction. The first liquid phase material from the second reactor after the reaction is recycled back into the emulsion mixing tank 3. The second liquid phase material 10 from the second reactor after the reaction enters the emulsion mixing tank 11. The mixed feedstock 12 from the third reactor enters the third reactor 13 for the third reaction. After the reaction, the residue oil staged deep desulfurization product 14 is obtained.

[0035] The following embodiments will further illustrate the method provided by the present invention, but do not limit the present invention.

[0036] The raw materials used in the examples and comparative examples were vacuum residue oil, the properties of which are shown in Table 1.

[0037] Table 1. Properties of vacuum residue feedstock

[0038]

[0039] Example 1

[0040] The residual oil feedstock, alkali metal, and hydrogen are mixed and then fed into the alkali metal treatment reaction zone for reaction. This zone comprises three alkali metal treatment reactors connected in series: a first reactor, a second reactor, and a third reactor. The alkali metal used is metallic sodium; the reactor type is a CSTR reactor.

[0041] 1. Vacuum residue feedstock and metallic sodium are mixed and premixed in an emulsifying mixer to obtain a highly dispersed mixture of liquid alkali metals. The mass ratio of metallic sodium to the inlet material of the first reactor is 0.070; the mixing temperature is 110℃, and the mixing time is 6 min. The size distribution range of the liquid alkali metals in the resulting mixture is 21-33 μm. The mixture is then fed into the first reactor, where the operating conditions are as follows: hydrogen pressure 5 MPa, reaction temperature 360℃, hydrogen-to-oil volume ratio 200, and residence time 15 min. The sulfur content of the outlet material of the first reactor decreases to 42.8% of the inlet sulfur content, and the thiophene sulfide content in the outlet material decreases to 44.9% of the inlet thiophene sulfide content. The sulfur content of the outlet material of the first reactor is 2.15 wt%, of which the thiophene sulfide content is 1.94 wt%; the metal content is 63 ppm.

[0042] 2. The material emanating from the first reactor is emulsified and mixed again with fresh metallic sodium, and then premixed in an emulsion mixer to obtain a highly dispersed liquid alkali metal mixture. This mixture then enters the second reactor. The mass ratio of metallic sodium to the material entering the second reactor is 0.046; the mixing temperature is 110 ℃, and the mixing time is 6 min. The operating conditions of the second reactor are as follows: hydrogen pressure is 5 MPa, reaction temperature is 350 ℃, hydrogen-to-oil volume ratio is 200, and residence time is 20 min.

[0043] The sulfur content of the outlet material from the second reactor decreased to 45.3% of the inlet sulfur content, and the thiophene sulfide content in the outlet material decreased to 47.5% of the inlet thiophene sulfide content. The sulfur content in the outlet material of the second reactor was 0.97 wt%, of which the thiophene sulfide content was 0.92 wt%; the metal content was 22 ppm.

[0044] 3. The material emanating from the second reactor is emulsified and mixed again with fresh metallic sodium, and then premixed in an emulsion mixer to obtain a highly dispersed liquid alkali metal mixture. This mixture then enters the third reactor. The mass ratio of metallic sodium to the material entering the third reactor is 0.030, the mixing temperature is 110 °C, and the mixing time is 6 min. The operating conditions of the third reactor are as follows: hydrogen pressure is 5 MPa, reaction temperature is 340 °C, hydrogen-to-oil volume ratio is 200, and residence time is 40 min.

[0045] The sulfur content of the effluent from the third reactor decreased to 43.1% of the influent sulfur content, and the thiophene sulfide content in the effluent decreased to 43.7% of the influent thiophene sulfide content. The sulfur content of the effluent from the third reactor was 0.42 wt%, of which the thiophene sulfide content was 0.40 wt%; the metal content was 8 ppm. The liquid phase yield was 98.4%.

[0046] Example 2

[0047] The residual oil feedstock, alkali metal, and hydrogen are mixed and then fed into the alkali metal treatment reaction zone for reaction. This zone comprises three alkali metal treatment reactors connected in series: a first reactor, a second reactor, and a third reactor. The alkali metal used is metallic sodium; the reactor type is a CSTR reactor.

[0048] 1. Vacuum residue feedstock and metallic sodium are mixed and premixed in an emulsifying mixer to obtain a highly dispersed mixture of liquid alkali metals. The mass ratio of metallic sodium to the inlet material of the first reactor is 0.090; the mixing temperature is 120℃, and the mixing time is 8 min. The size distribution range of the liquid alkali metals in the resulting mixture is 16-29 μm. The mixture is then fed into the first reactor, where the operating conditions are as follows: hydrogen pressure 6 MPa, reaction temperature 340℃, hydrogen-to-oil volume ratio 300, and residence time 15 min. The sulfur content of the outlet material of the first reactor decreases to 33.9% of the inlet sulfur content, and the thiophene sulfide content in the outlet material decreases to 35.3% of the inlet thiophene sulfide content. The sulfur content of the outlet material of the first reactor is 1.70 wt%, of which the thiophene sulfide content is 1.52 wt%; the metal content is 54 ppm.

[0049] 2. The material emanating from the first reactor is emulsified and mixed again with fresh metallic sodium, and then premixed in an emulsion mixer to obtain a highly dispersed liquid alkali metal mixture. This mixture then enters the second reactor. The mass ratio of metallic sodium to the material entering the second reactor is 0.063; the mixing temperature is 120 °C; and the mixing time is 8 min. The operating conditions of the second reactor are as follows: hydrogen pressure is 6 MPa, reaction temperature is 330 °C, hydrogen-to-oil volume ratio is 300, and residence time is 20 min.

[0050] The sulfur content of the effluent from the second reactor decreased to 35.4% of the sulfur content of the influent, and the thiophene sulfide content in the effluent decreased to 37.2% of the thiophene sulfide content in the influent. The sulfur content in the effluent from the second reactor was 0.60 wt%, of which the thiophene sulfide content was 0.57 wt%; the metal content was 16 ppm.

[0051] 3. The material emanating from the second reactor is emulsified and mixed again with fresh metallic sodium, then premixed in an emulsion mixer to obtain a highly dispersed liquid alkali metal mixture. This mixture then enters the third reactor. The mass ratio of metallic sodium to the material entering the third reactor is 0.044, the mixing temperature is 120 °C, and the mixing time is 8 min. The operating conditions of the third reactor are as follows: hydrogen pressure 6 MPa, reaction temperature 320 °C, hydrogen-to-oil volume ratio 300, and residence time 45 min.

[0052] The sulfur content of the effluent from the third reactor decreased to 35.6% of the influent sulfur content, and the thiophene sulfide content in the effluent decreased to 37.0% of the influent thiophene sulfide content. The sulfur content of the effluent from the third reactor was 0.21 wt%, of which the thiophene sulfide content was 0.20 wt%; the metal content was 5 ppm. The liquid phase yield was 97.9%.

[0053] Example 3

[0054] The residual oil feedstock, alkali metal, and hydrogen are mixed and then fed into the alkali metal treatment reaction zone for reaction. This zone comprises four alkali metal treatment reactors connected in series: reactor one, reactor two, reactor three, and reactor four. The alkali metal used is metallic sodium; the reactor type is a CSTR reactor.

[0055] 1. Vacuum residue feedstock and metallic sodium are mixed and premixed in an emulsifying mixer to obtain a highly dispersed mixture of liquid alkali metals. The mass ratio of metallic sodium to the inlet material of the first reactor is 0.050; the mixing temperature is 110℃, and the mixing time is 6 min. The size distribution range of the liquid alkali metals in the resulting mixture is 26-41 μm. The mixture is then fed into the first reactor, where the operating conditions are as follows: hydrogen pressure 5 MPa, reaction temperature 370℃, hydrogen-to-oil volume ratio 200, and residence time 15 min. The sulfur content of the outlet material of the first reactor decreases to 54.8% of the inlet sulfur content, and the thiophene sulfide content in the outlet material decreases to 55.9% of the inlet thiophene sulfide content. The sulfur content of the outlet material of the first reactor is 2.75 wt%, of which the thiophene sulfide content is 2.43 wt%; the metal content is 81 ppm.

[0056] 2. The material emanating from the first reactor is emulsified and mixed again with fresh metallic sodium, and then premixed in an emulsion mixer to obtain a highly dispersed liquid alkali metal mixture. This mixture then enters the second reactor. The mass ratio of metallic sodium to the material entering the second reactor is 0.032; the mixing temperature is 110 ℃; and the mixing time is 6 min. The operating conditions of the second reactor are as follows: hydrogen pressure is 5 MPa, reaction temperature is 360 ℃, hydrogen-to-oil volume ratio is 200, and residence time is 25 min.

[0057] The sulfur content of the effluent from the second reactor decreased to 54.8% of the sulfur content of the influent, and the thiophene sulfide content in the effluent decreased to 55.6% of the thiophene sulfide content in the influent. The sulfur content in the effluent from the second reactor was 1.51 wt%, of which the thiophene sulfide content was 1.35 wt%; the metal content was 36 ppm.

[0058] 3. The material emanating from the second reactor is emulsified and mixed again with fresh metallic sodium, and then premixed in an emulsion mixer to obtain a highly dispersed liquid alkali metal mixture. This mixture then enters the third reactor. The mass ratio of metallic sodium to the material entering the third reactor is 0.020, the mixing temperature is 110 ℃, and the mixing time is 6 min. The operating conditions of the third reactor are as follows: hydrogen pressure is 5 MPa, reaction temperature is 350 ℃, hydrogen-to-oil volume ratio is 200, and residence time is 48 min.

[0059] The sulfur content of the outlet material from the third reactor decreased to 54.9% of the inlet sulfur content, and the thiophene sulfide content in the outlet material decreased to 55.7% of the inlet thiophene sulfide content. The sulfur content of the outlet material from the third reactor was 0.83 wt%, of which the thiophene sulfide content was 0.75 wt%; the metal content was 16 ppm.

[0060] 4. The material emanating from the third reactor is emulsified and mixed again with fresh metallic sodium, and then premixed in an emulsion mixer to obtain a highly dispersed liquid alkali metal mixture. This mixture then enters the fourth reactor. The mass ratio of metallic sodium to the material entering the fourth reactor is 0.013, the mixing temperature is 110 ℃, and the mixing time is 6 min. The operating conditions of the fourth reactor are as follows: hydrogen pressure is 5 MPa, reaction temperature is 340 ℃, hydrogen-to-oil volume ratio is 200, and residence time is 52 min.

[0061] The sulfur content of the outlet feed from the fourth reactor decreased to 55.4% of the inlet feed's sulfur content, and the thiophene sulfide content in the outlet feed decreased to 56.0% of the inlet feed's thiophene sulfide content. The sulfur content of the outlet feed from the fourth reactor was 0.46 wt%, of which the thiophene sulfide content was 0.42 wt%; the metal content was 7 ppm. The liquid phase yield was 99.2%.

[0062] Example 4

[0063] The residual oil feedstock, the first liquid phase material from the second reactor, alkali metal, and hydrogen are mixed and then fed into the alkali metal treatment reaction zone for reaction. The alkali metal treatment reaction zone includes three alkali metal treatment reactors connected in series: the first reactor, the second reactor, and the third reactor. The alkali metal used is metallic sodium; the reactor type used is a CSTR reactor.

[0064] 1. Vacuum residue feedstock, the first liquid phase material from the second reactor, and metallic sodium are mixed and premixed in an emulsifying mixer to obtain a highly dispersed mixture of liquid alkali metals. The mass ratio of metallic sodium to the inlet material of the first reactor is 0.070; the mixing temperature is 110 ℃, and the mixing time is 6 min. The size distribution range of the liquid alkali metals in the resulting mixture is 21-33 μm. This mixture is then fed into the first reactor, where the operating conditions are as follows: hydrogen pressure 5 MPa, reaction temperature 350 ℃, hydrogen-to-oil volume ratio 200, and residence time 15 min. The sulfur content of the outlet material from the first reactor decreases to 43.9% of the inlet sulfur content, and the thiophene sulfide content in the outlet material decreases to 44.9% of the inlet thiophene sulfide content. The sulfur content of the outlet material from the first reactor is 1.74 wt%, of which the thiophene sulfide content is 1.54 wt%; the metal content is 41 ppm.

[0065] 2. The material emanating from the first reactor is emulsified and mixed again with fresh metallic sodium, and then premixed in an emulsion mixer to obtain a highly dispersed liquid alkali metal mixture. This mixture then enters the second reactor. The mass ratio of metallic sodium to the material entering the second reactor is 0.046; the mixing temperature is 110 ℃, and the mixing time is 6 min. The operating conditions of the second reactor are as follows: hydrogen pressure is 5 MPa, reaction temperature is 340 ℃, hydrogen-to-oil volume ratio is 200, and residence time is 30 min.

[0066] The sulfur content of the effluent from the second reactor decreased to 44.2% of the sulfur content of the influent, and the thiophene sulfide content in the effluent decreased to 55.6% of the thiophene sulfide content in the influent. The sulfur content in the effluent from the second reactor was 0.77 wt%, of which the thiophene sulfide content was 0.69 wt%; the metal content was 14 ppm.

[0067] The material emanating from the second reactor is divided into two streams: a first liquid phase and a second liquid phase. The mass ratio of the first liquid phase to the second liquid phase is 0.5. The first liquid phase is recycled back to the first reactor, and the second liquid phase enters the third reactor.

[0068] 3. The second liquid phase material in the second reactor is emulsified and mixed with fresh metallic sodium again, and then enters an emulsion mixer for premixing to obtain a highly dispersed liquid alkali metal mixture. This mixture then enters the third reactor. The mass ratio of metallic sodium to the inlet material of the third reactor is 0.030, the mixing temperature is 110 ℃, and the mixing time is 6 min. The operating conditions of the third reactor are as follows: hydrogen pressure is 5 MPa, reaction temperature is 330 ℃, hydrogen-to-oil volume ratio is 200, and residence time is 50 min.

[0069] The sulfur content of the effluent from the third reactor decreased to 45.5% of the sulfur content of the influent, and the thiophene sulfide content in the effluent decreased to 46.3% of the thiophene sulfide content in the influent. The sulfur content of the effluent from the third reactor was 0.35 wt%, of which the thiophene sulfide content was 0.32 wt%; the metal content was 8 ppm. The liquid phase yield was 98.6%.

[0070] Example 5

[0071] The residual oil feedstock, the first liquid phase material from the second reactor, alkali metal, and hydrogen are mixed and then fed into the alkali metal treatment reaction zone for reaction. The alkali metal treatment reaction zone includes three alkali metal treatment reactors connected in series: the first reactor, the second reactor, and the third reactor. The alkali metal used is metallic sodium; the reactor type used is a CSTR reactor.

[0072] 1. The vacuum residue feedstock, the first liquid phase material from the second reactor, and metallic sodium are mixed and premixed in an emulsifying mixer to obtain a highly dispersed mixture of liquid alkali metals. The mass ratio of metallic sodium to the inlet material of the first reactor is 0.090; the mixing temperature is 120 °C, and the mixing time is 8 min. The size distribution range of the liquid alkali metals in the resulting mixture is 16-29 μm. This mixture is then fed into the first reactor, where the operating conditions are as follows: hydrogen pressure 6 MPa, reaction temperature 340 °C, hydrogen-to-oil volume ratio 300, and residence time 18 min. The sulfur content of the first reactor outlet material decreases to 32.8% of the inlet material's sulfur content, and the thiophene sulfide content in the outlet material decreases to 33.5% of the inlet material's thiophene sulfide content. The sulfur content of the first reactor outlet material is 1.21 wt%, of which the thiophene sulfide content is 1.06 wt%; the metal content is 39 ppm.

[0073] 2. The material emanating from the first reactor is emulsified and mixed again with fresh metallic sodium, and then premixed in an emulsion mixer to obtain a highly dispersed liquid alkali metal mixture. This mixture then enters the second reactor. The mass ratio of metallic sodium to the material entering the second reactor is 0.063; the mixing temperature is 120 °C; and the mixing time is 8 min. The operating conditions of the second reactor are as follows: hydrogen pressure is 6 MPa, reaction temperature is 330 °C, hydrogen-to-oil volume ratio is 300, and residence time is 30 min.

[0074] The sulfur content of the effluent from the second reactor decreased to 37.2% of the sulfur content of the influent, and the thiophene sulfide content in the effluent decreased to 37.7% of the thiophene sulfide content in the influent. The sulfur content in the effluent from the second reactor was 0.45 wt%, of which the thiophene sulfide content was 0.40 wt%; the metal content was 12 ppm.

[0075] The material emanating from the second reactor is divided into two streams: a first liquid phase and a second liquid phase. The mass ratio of the first liquid phase to the second liquid phase is 0.7. The first liquid phase is recycled back to the first reactor, and the second liquid phase enters the third reactor.

[0076] 3. The second liquid phase material in the second reactor is emulsified and mixed with fresh metallic sodium again, and then enters an emulsifying mixer for premixing to obtain a highly dispersed liquid alkali metal mixture. This mixture then enters the third reactor. The mass ratio of metallic sodium to the inlet material of the third reactor is 0.044, the mixing temperature is 120 ℃, and the mixing time is 8 min. The operating conditions of the third reactor are as follows: hydrogen pressure is 6 MPa, reaction temperature is 320 ℃, hydrogen-to-oil volume ratio is 300, and residence time is 55 min.

[0077] The sulfur content of the effluent from the third reactor decreased to 35.6% of the influent sulfur content, and the thiophene sulfide content in the effluent decreased to 37.5% of the influent thiophene sulfide content. The sulfur content of the effluent from the third reactor was 0.16 wt%, of which the thiophene sulfide content was 0.15 wt%; the metal content was 4 ppm. The liquid phase yield was 97.5%.

[0078] Comparative Example 1

[0079] The residual oil feedstock, metallic sodium, and hydrogen are mixed and then fed into the alkali metal treatment reaction zone for reaction. The alkali metal treatment reaction zone is equipped with only one alkali metal treatment reactor.

[0080] Vacuum residue feedstock was mixed with metallic sodium and premixed in an emulsifying mixer to obtain a highly dispersed mixture of liquid alkali metals. The mass ratio of metallic sodium to reactor inlet material was 0.13; the mixing temperature was 110 °C; and the mixing time was 6 min. The size distribution of the liquid alkali metals in the resulting mixture ranged from 11 to 26 μm. The mixture was then fed into an alkali metal treatment reactor under the following operating conditions: hydrogen pressure of 5 MPa, reaction temperature of 360 °C, hydrogen-to-oil volume ratio of 200, and residence time of 55 min.

[0081] The sulfur content of the effluent from the alkali metal treatment reactor was 0.82 wt%, of which thiophene sulfides accounted for 0.69 wt%; the metal content was 32 ppm. For example... Figure 2 As shown, during the experiment of Comparative Example 1, a large amount of coking byproducts were generated by a side reaction. The liquid phase yield was 77.1%.

Claims

1. A method for processing residual oil, characterized in that: The method includes the following steps: Residual oil feedstock, alkali metal, and hydrogen are mixed and then introduced into an alkali metal treatment reaction zone for reaction. The alkali metal treatment reaction zone includes two or more alkali metal treatment reactors connected in series. When the sulfur content of the outlet material of any alkali metal treatment reactor in the alkali metal treatment reaction zone decreases to 15%–70% of the sulfur content of the inlet material, and simultaneously the thiophene sulfide content in the outlet material decreases to 20%–60% of the thiophene sulfide content in the inlet material, the material from that alkali metal treatment reactor enters a downstream alkali metal treatment reactor connected in series, until the properties of the outlet material of the alkali metal treatment reactor meet the requirements: sulfur content not greater than 0.5 wt%, metal content not greater than 10 ppm. The mass ratio of the alkali metal to the inlet material of the alkali metal treatment reactor is 0.02-0.15; The inlet material of the alkali metal treatment reactor is partially or completely mixed with alkali metal in a mixer to obtain a highly dispersed liquid alkali metal mixture. The mixture is then mixed with hydrogen and enters the alkali metal treatment reactor for reaction. The reaction conditions are as follows: hydrogen pressure of 2-10 MPa, reaction temperature of 240-380℃, hydrogen-to-oil volume ratio of 100-400, and reaction residence time of 5-30 min.

2. The method for processing residual oil according to claim 1, characterized in that: When the sulfur content of the outlet material of any alkali metal treatment reactor in the alkali metal treatment reaction zone decreases to 25% to 60% of the sulfur content of the inlet material, and at the same time the thiophene sulfide content in the outlet material decreases to 25% to 55% of the thiophene sulfide content in the inlet material, the material of that alkali metal treatment reactor enters the downstream alkali metal treatment reactors arranged in series.

3. The method for processing residual oil according to claim 1, characterized in that: The alkali metal treatment reaction zone includes 3 to 8 alkali metal treatment reactors connected in series.

4. The method for processing residual oil according to claim 1, characterized in that: The alkali metal treatment reaction zone includes three or four alkali metal treatment reactors connected in series.

5. The method for processing residual oil according to claim 1, characterized in that: When the alkali metal treatment reactors connected in series in the alkali metal treatment reaction zone adopt different feed ratios, the mass ratio of alkali metal to the inlet material of the alkali metal treatment reactor in the two adjacent alkali metal treatment reactors is controlled. The mass ratio of alkali metal to the inlet material of the alkali metal treatment reactor in the downstream alkali metal treatment reactor is 20% to 55% lower than that in the upstream alkali metal treatment reactor.

6. The method for processing residual oil according to claim 5, characterized in that: When the alkali metal treatment reactors connected in series in the alkali metal treatment reaction zone adopt different feed ratios, the mass ratio of alkali metal to the inlet material of the alkali metal treatment reactor in the two adjacent alkali metal treatment reactors is controlled. The mass ratio of alkali metal to inlet material in the downstream alkali metal treatment reactor is 30% to 45% lower than that in the upstream alkali metal treatment reactor.

7. The method for processing residual oil according to claim 1, characterized in that: When the alkali metal treatment reactors connected in series in the alkali metal treatment reaction zone adopt different operating conditions, the operating temperature difference between two adjacent alkali metal treatment reactors is controlled to be 5-15℃.

8. The method for processing residual oil according to claim 7, characterized in that: When the alkali metal treatment reactors connected in series in the alkali metal treatment reaction zone adopt different operating conditions, the operating temperature difference between two adjacent alkali metal treatment reactors is controlled to be 8~10℃.

9. The method for processing residual oil according to claim 1, characterized in that: In the alkali metal treatment reaction zone, the outlet material of at least one alkali metal treatment reactor is divided into two streams, namely a first liquid phase material and a second liquid phase material; the first liquid phase material is circulated to any one of the alkali metal treatment reactors, and the second liquid phase material enters a downstream alkali metal treatment reactor arranged in series; the mass ratio of the first liquid phase material to the second liquid phase material is 0.2-1.

5.

10. The method for processing residual oil according to claim 9, characterized in that: The mass ratio of the first liquid phase material to the second liquid phase material is 0.4-0.

8.

11. The method for processing residual oil according to claim 1, characterized in that: The alkali metal is at least one of Li, Na, and K.

12. The method for processing residual oil according to claim 11, characterized in that: The alkali metal is Na.

13. The method for processing residual oil according to claim 1, characterized in that: The mass ratio of the alkali metal to the inlet material of the alkali metal treatment reactor is 0.03-0.

07.

14. The method for processing residual oil according to claim 1, characterized in that: The alkali metal treatment reactor is one or more of the following: intermittent high-pressure reactor, CSTR reactor, and pipeline reactor.

15. The method for processing residual oil according to claim 14, characterized in that: The alkali metal treatment reactor is a pipeline reactor.

16. The method for processing residual oil according to claim 1, characterized in that: The mixing temperature is 95-150℃; the mixing time is 3-10 min.

17. The method for processing residual oil according to claim 16, characterized in that: The mixing temperature is 100-120℃; the mixing time is 5-8 minutes.

18. The method for processing residual oil according to claim 1, characterized in that: The liquid alkali metal in the highly dispersed mixture has a size distribution range of 15-85 μm.

19. The method for processing residual oil according to claim 1, characterized in that: The liquid alkali metal in the highly dispersed mixture has a size distribution range of 20-35 μm.

20. The method for processing residual oil according to claim 1, characterized in that: The reaction conditions are as follows: hydrogen pressure of 3-6 MPa, reaction temperature of 290-340℃, hydrogen-to-oil volume ratio of 200-300, and reaction residence time of 10-20 min.

21. The method for processing residual oil according to claim 1, characterized in that: The residual oil feedstock has a sulfur content of 3.5-7.0 wt%, a thiophene sulfide content of 1.8-4.5 wt%, and a metal content of 120-260 ppm.

22. The method for processing residual oil according to claim 21, characterized in that: The residual oil feedstock has a sulfur content of 4.0-6.0 wt%, a thiophene sulfide content of 2.6-3.8 wt%, and a metal content of 160-240 ppm.

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