Coal-based fischer-tropsch synthesis fuel oil, method for preparing same, and use thereof

Abstract

The application provides a coal-based Fischer-Tropsch synthesis fuel oil, a preparation method and application thereof. The preparation method of the coal-based Fischer-Tropsch synthesis fuel oil is as follows: first fractionating, hydrofining and second fractionating of Fischer-Tropsch synthesis crude oil to obtain a hydrofining diesel oil fraction and a hydrofining tail oil; then, hydrocracking and third fractionating of the hydrofining tail oil to obtain a hydrocracking diesel oil fraction; in addition, rectification of each hydrocracking diesel oil fraction to obtain a side line component and the coal-based Fischer-Tropsch synthesis fuel oil; finally, fractionating of the side line component to obtain the coal-based Fischer-Tropsch synthesis fuel oil. The coal-based Fischer-Tropsch synthesis fuel oil is prepared by fractionating, hydrofining, hydrocracking and fractionating of the coal indirect liquefaction Fischer-Tropsch synthesis crude oil. Compared with the petroleum-based fuel oil, the coal-based Fischer-Tropsch synthesis fuel oil has low sulfur and nitrogen contents, low acid value, low ash content, rich raw material resources and wide sources, and can be applied to household or industrial small-scale burners.

Description

Technical Field

[0001] This invention relates to the field of coal chemical technology, and more specifically, to a coal-based Fischer-Tropsch synthetic fuel oil, its preparation method, and its application. Background Technology

[0002] Fuel oil, as a refined petroleum product, is a heavier residual product separated from crude oil during petroleum processing, after gasoline, kerosene, and diesel. It is mainly made from cracked petroleum residue and straight-run residue, characterized by high viscosity and a high content of non-hydrocarbon compounds, gums, and asphaltenes. It is widely used in household and marine engines or industrial burners. Compared to gasoline, diesel, and jet fuel used in internal combustion engines, fuel oil generally belongs to the category of heavier-fraction fuel oils or residual fuel oils.

[0003] Fuel oil should be free of inorganic acids, excessive solids, and foreign fibrous substances. Furthermore, it should possess good atomization performance and low corrosivity, as well as low levels of gum and asphaltenes to ensure complete combustion and minimize coking, thereby extending the furnace's service life. Key performance indicators for fuel oil include viscosity, low-temperature performance, sulfur content, and stability. Sulfur compounds in fuel oil produce SO2 and SO3 upon combustion. SO2 and SO3 not only pollute the environment and harm human health, but also, upon contact with water, form sulfurous acid and sulfuric acid, which severely corrode metal equipment. Therefore, the lower the sulfur content in fuel oil, the better.

[0004] Current fuel oils are primarily derived from petroleum-based products, mainly from cracked petroleum and straight-run residues. Petroleum-based fuel oils have a high sulfur content and are not clean. Furthermore, given that my country is a major coal-producing country with limited petroleum resources, and with the continuous growth in my country's fuel oil demand, new fuel oil alternatives are attracting increasing attention.

[0005] Invention patent CN 110229686 A discloses a low-sulfur marine distillate fuel oil and its preparation method. The deep-processed oil from direct liquefaction of coal powder is fractionated and cut into A-1 base oil (180–380℃) or A-2 base oil (160–340℃) to obtain low-sulfur marine distillate fuel oil. This invention only requires adding a small amount of thickener to the directly blended DMA oil to obtain a marine distillate fuel oil of type DMZ. This marine distillate fuel oil has the advantages of very low sulfur and nitrogen content, low acid value, low ash content, and good low-temperature fluidity. Invention patent CN 114752411 A discloses a method for preparing multi-purpose fuel oil. Direct coal liquefaction oil is cut to obtain a light component with a boiling point ≤220℃ and a heavy component with a boiling point >220℃. The liquid phase oil obtained by two-step hydrogenation of the heavy component is mixed with the light component and then fractionated to obtain a multi-purpose fuel oil with a boiling point ≥160℃. It can be used in jet aircraft, ground vehicles, and watercraft, and is suitable for industrial application. However, the above methods all use direct coal liquefaction oil as raw material for fuel oil production, which still has the drawback of high sulfur and aromatic hydrocarbon content in the oil. Summary of the Invention

[0006] The main objective of this invention is to provide a coal-based Fischer-Tropsch synthetic fuel oil, its preparation method, and its application, in order to solve the problems of high sulfur content, uncleanliness, and shortage of raw material resources in existing fuel oils.

[0007] To achieve the above objectives, according to one aspect of the present invention, a method for preparing coal-based Fischer-Tropsch synthetic fuel oil is provided. The preparation method includes the following steps: Step S1, using coal as raw material, Fischer-Tropsch synthetic crude oil is prepared via an indirect coal liquefaction Fischer-Tropsch synthesis reaction; the Fischer-Tropsch synthetic crude oil is subjected to a first fractionation to obtain Fischer-Tropsch stabilized heavy oil; Step S2, the Fischer-Tropsch stabilized heavy oil is hydrorefined to obtain a hydrorefined product; the hydrorefined product is subjected to a second fractionation to obtain a hydrorefined diesel fraction, a hydrorefined tail oil, and a hydrorefined gasoline fraction with a boiling point <195℃; Step S3, the hydrorefined gasoline is further refined by hydrorefining the tail oil. Hydrogen-refined tail oil is subjected to hydrocracking to obtain hydrocracking products; the hydrocracking products are then subjected to a third fractionation to obtain hydrocracking tail oil, hydrocracking gasoline fraction, and hydrocracking diesel fraction; wherein the initial boiling point of the hydrocracking diesel fraction is 160-180℃, and the final boiling point is 280-350℃; in step S4, the hydrocracking diesel fraction and the hydrocracking diesel fraction are fed into a distillation column for distillation to obtain light diesel oil components at the top of the distillation column and components on the side of the distillation column. The distillation column contains a first fuel oil component, a second fuel oil component (side stream), and a first coal-based Fischer-Tropsch synthetic fuel oil. The first fuel oil component (side stream) has an initial boiling point of 120–160°C and a final boiling point of 230–250°C; the second fuel oil component (side stream) has an initial boiling point of 130–160°C and a final boiling point of 250–275°C; and the first coal-based Fischer-Tropsch synthetic fuel oil has an initial boiling point of 220–240°C and a final boiling point of 300–320°C. Step S5: The first fuel oil component from the distillation column side stream is subjected to a fourth fractionation to obtain a second coal-based Fischer-Tropsch synthetic fuel oil; the second fuel oil component from the distillation column side stream is subjected to a fifth fractionation to obtain a third coal-based Fischer-Tropsch synthetic fuel oil; wherein the initial boiling point of the second coal-based Fischer-Tropsch synthetic fuel oil is 170-195℃ and the final boiling point is 230-250℃, and the initial boiling point of the third coal-based Fischer-Tropsch synthetic fuel oil is 225-245℃ and the final boiling point is 250-275℃.

[0008] Further, in step S1, the preparation step of Fischer-Tropsch crude oil is as follows: coal is gasified to obtain syngas, and the syngas is subjected to Fischer-Tropsch synthesis reaction to prepare Fischer-Tropsch crude oil; wherein, the syngas includes H2 and CO, and the molar ratio of the two is (1.3-1.9):1; preferably, the reaction temperature of coal gasification is 1200-1750℃; and / or the reaction pressure is 3-5 MPa; and / or the coal includes one or more of lignite, bituminous coal and anthracite; and / or the catalyst for the Fischer-Tropsch synthesis reaction includes one or more of Fe-based catalysts, Co-based catalysts, Ni-based catalysts and Ru-based catalysts.

[0009] Furthermore, in step S1, the first fractionation is carried out in the first fractionation column, the bottom temperature of the first fractionation column is 300-350℃, and the top pressure is 0.1-0.2MPa.

[0010] Further, in step S2, the reaction temperature for hydrorefining is 250–350°C, preferably 260–300°C; and / or the reaction pressure is 2–8 MPa, preferably 3–6 MPa; and / or the volume hourly space velocity is 0.5–3 h⁻¹. -1 Preferably 0.5 to 2 hours -1 The hydrogen-to-oil ratio is 200–700, preferably 250–400; the hydrogen-refining catalyst comprises a first support and a first active metal component supported on the first support; preferably, the mass ratio of the first active metal component to the first support is (3–8):1000; the first support comprises one or more of silicon oxide, alumina, and titanium oxide; the first active metal component comprises one or more of Co, Pt, Pd, Ni, W, and Mo; and the second fractionation is carried out in a second fractionation column, the bottom temperature of the second fractionation column is 280–350°C, preferably 310–340°C; the top temperature is 100–145°C, preferably 100–130°C; and the bottom pressure is 0.1–1.1 MPa, preferably 0.2–0.6 MPa.

[0011] Further, in step S3, the hydrocracking reaction temperature is 300–380°C, preferably 300–350°C; and / or the reaction pressure is 2–8 MPa, preferably 3–7 MPa; and / or the volume hourly space velocity is 0.5–3.5 h⁻¹. -1 Preferably, it is 0.5 to 1.5 hours. -1 The hydrogen-to-oil ratio is 200–800, preferably 200–500; the hydrocracking catalyst comprises a second support and a second active metal component supported on the second support; preferably, the mass ratio of the second active metal component to the second support is (2–7):1000; the second support comprises one or more of silicon oxide, alumina, and titanium oxide; the second active metal component comprises one or more of Co, Pt, Pd, Ni, W, and Mo; and the third fractionation is carried out in a third fractionation column, the bottom temperature of the third fractionation column is 290–360°C, preferably 300–335°C; the top temperature is 100–160°C, preferably 100–140°C; and the bottom pressure is 0.1–1.2 MPa, preferably 0.1–0.6 MPa.

[0012] Further, in step S4, the hydrorefined diesel fraction and the hydrocracking diesel fraction are first mixed, and then distilled in the same distillation column; preferably, the mass ratio of the hydrorefined diesel fraction and the hydrocracking diesel fraction is (1-50):1; and / or the hydrorefined diesel fraction and the hydrocracking diesel fraction are distilled in the same distillation column with a switching feed method; preferably, the mass ratio of the hydrorefined diesel fraction and the hydrocracking diesel fraction is (1-50):1; and / or the hydrorefined diesel fraction and the hydrocracking diesel fraction are fed into different distillation columns with independent feed methods for distillation.

[0013] Furthermore, in step S4, the top temperature of the distillation column is 70–110°C; and / or the bottom temperature is 200–280°C; and / or the top pressure is 15–25 kPa.

[0014] Further, in step S5, the fourth fractionation is carried out in the first side-stream column, where the bottom temperature of the first side-stream column is 140–190°C; and / or the top temperature is 50–90°C; and / or the bottom pressure is 0.1–1 MPa; and / or the fifth fractionation is carried out in the second side-stream column, where the bottom temperature of the second side-stream column is 180–220°C; and / or the top temperature is 80–100°C; and / or the bottom pressure is 0.1–1 MPa.

[0015] According to another aspect of the present invention, a coal-based Fischer-Tropsch synthetic fuel oil is provided, which is obtained by the preparation method described above.

[0016] According to another aspect of the invention, the application of the above-described coal-based Fischer-Tropsch synthetic fuel oil in domestic and / or industrial burners is provided.

[0017] By applying the technical solution of this invention, three types of fuel oil were prepared from crude oil obtained through indirect coal liquefaction Fischer-Tropsch synthesis via fractionation, hydrorefining, hydrocracking, and further fractionation. Compared with petroleum-based fuel oil, coal-based Fischer-Tropsch synthesis fuel oil has lower sulfur and nitrogen content, lower acid value, and lower ash content, making it a clean and environmentally friendly alternative to furnace fuel oil. Furthermore, it is made from abundant and widely available raw materials and can be used in small household or industrial burners. Attached Figure Description

[0018] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0019] Figure 1 A schematic diagram of the process flow for preparing coal-based Fischer-Tropsch synthetic fuel oil according to Embodiment 1 of the present invention is shown.

[0020] The above figures include the following reference numerals:

[0021] 1. Fischer-Tropsch reactor for indirect coal liquefaction; 2. First fractionation column; 3. Hydrorefining reactor; 4. Second fractionation column; 5. Hydrocracking reactor; 6. Third fractionation column; 7. Storage tank; 8. Feed pump; 9. Distillation column; 10. First side-stream column; 11. Second side-stream column;

[0022] A. Raw material; B. Fischer-Tropsch crude oil; C. First fraction; D. Fischer-Tropsch stabilized heavy oil; E. Hydrorefining product; F. Hydrorefined gasoline fraction; G. Hydrorefined diesel fraction; H. Hydrorefining tail oil; I. Hydrocracking product; J. Hydrocracking gasoline fraction; K. Hydrocracking diesel fraction; L. Hydrocracking tail oil; M. Mixed fraction; N. Second fraction; O. First fuel oil component from distillation column side stream; P. Second fuel oil component from distillation column side stream; Q. First coal-based Fischer-Tropsch synthetic fuel oil; R. Third fraction; S. Second coal-based Fischer-Tropsch synthetic fuel oil; T. Fourth fraction; U. Third coal-based Fischer-Tropsch synthetic fuel oil. Detailed Implementation

[0023] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0024] As described in the background section of this invention, existing technologies suffer from problems such as high sulfur content, uncleanliness, and a shortage of raw material resources in fuel oil. To address these issues, in a typical embodiment of this invention, a method for preparing coal-based Fischer-Tropsch synthetic fuel oil is provided. This method includes the following steps: Step S1, using coal as raw material, Fischer-Tropsch synthetic crude oil is prepared via an indirect coal liquefaction Fischer-Tropsch synthesis reaction; the Fischer-Tropsch synthetic crude oil undergoes a first fractionation to obtain Fischer-Tropsch stabilized heavy oil; Step S2, the Fischer-Tropsch stabilized heavy oil is hydrorefined to obtain a hydrorefined product; the hydrorefined product undergoes a second fractionation to obtain a hydrorefined diesel fraction, a hydrorefined tail oil, and a hydrorefined gasoline fraction with a boiling point <195℃; Step S3, ... The hydrorefined tail oil is subjected to hydrocracking to obtain hydrocracking products; the hydrocracking products are then subjected to a third fractionation to obtain hydrocracking tail oil, hydrocracking gasoline fraction, and hydrocracking diesel fraction; wherein the initial boiling point of the hydrocracking diesel fraction is 160-180℃, and the final boiling point is 280-350℃; in step S4, the hydrorefined diesel fraction and the hydrocracking diesel fraction are fed into a distillation column for distillation to obtain a light diesel component at the top of the distillation column and a distillation column... The distillation column contains a first side-stream fuel oil component, a second side-stream fuel oil component, and a first coal-based Fischer-Tropsch synthetic fuel oil. The first side-stream fuel oil component has an initial boiling point of 120–160°C and a final boiling point of 230–250°C; the second side-stream fuel oil component has an initial boiling point of 130–160°C and a final boiling point of 250–275°C; and the first coal-based Fischer-Tropsch synthetic fuel oil has an initial boiling point of 220–240°C and a final boiling point of 300–320°C. ℃; Step S5, the first fuel oil component from the distillation column side stream is subjected to a fourth fractionation to obtain a second coal-based Fischer-Tropsch synthetic fuel oil; the second fuel oil component from the distillation column side stream is subjected to a fifth fractionation to obtain a third coal-based Fischer-Tropsch synthetic fuel oil; wherein, the initial boiling point of the second coal-based Fischer-Tropsch synthetic fuel oil is 170-195℃ and the final boiling point is 230-250℃, and the initial boiling point of the third coal-based Fischer-Tropsch synthetic fuel oil is 225-245℃ and the final boiling point is 250-275℃.

[0025] With increasingly stringent environmental protection requirements, the preparation of low-sulfur new energy fuel oils has become particularly important. Currently, most reported fuel oils are petroleum-based, with fewer reports on coal-based fuel oils, and no reports on coal-based Fischer-Tropsch synthetic fuel oils have been found. In the coal-based Fischer-Tropsch synthetic fuel oil preparation method provided in this invention, coal is used as raw material. Through an indirect coal liquefaction Fischer-Tropsch synthesis reaction, the coal is gasified with oxygen and steam to obtain syngas (a mixture of H2 and CO). Subsequently, the syngas reacts under the action of a Fischer-Tropsch synthesis catalyst to produce Fischer-Tropsch crude oil containing liquid hydrocarbons, waxes, gaseous light hydrocarbons, and some organic oxygen-containing compounds. Due to the influence of hydrogen in the syngas, the sulfides in the syngas are hydrocracking, and the sulfur content, acid value, and ash content of the crude oil are significantly reduced. Through the coal indirect Fischer-Tropsch synthesis reaction process, a clean crude oil with low sulfur content, low acid value, and low ash content can be prepared.

[0026] The crude oil is then fractionated to obtain Fischer-Tropsch stabilized heavy oil, which is mainly composed of olefins and alkanes. It should be noted that after the first fractionation, light components such as naphtha are also obtained, which can be used to produce gasoline.

[0027] Next, the Fischer-Tropsch stabilized heavy oil is hydrorefined. Hydrogenation effectively reduces the content of unsaturated substances such as olefins in the heavy oil. Furthermore, because non-hydrocarbon compounds such as sulfur, oxygen, and nitrogen are converted into easily removable hydrogen sulfide, water, and ammonia through hydrorefining, impurities such as sulfur, nitrogen, and oxygen in the heavy oil can be effectively removed, purifying the heavy oil components and improving the yield, quality, and purity of the target product, fuel oil. Moreover, because unstable olefins and aromatics are saturated during hydrorefining, unstable molecules in the heavy oil can be effectively removed, improving the stability and reliability of the target product, fuel oil. The obtained hydrorefined product is fractionated to obtain hydrorefined diesel fraction, hydrorefined tail oil, and hydrorefined gasoline fraction with a boiling point <195℃. The hydrorefined diesel fraction is fed into a distillation column for further distillation. The hydrorefined gasoline fraction with a boiling point <195℃ mainly contains light components such as naphtha, which can be used to produce gasoline.

[0028] The hydrorefined tail oil is then subjected to hydrocracking. During hydrocracking, heavy hydrocarbons such as long-chain alkanes in the hydrorefined tail oil are decomposed into light hydrocarbon molecules such as high-octane gasoline, high-olefin liquefied petroleum gas, benzene, and ethylene. This improves the flowability and flammability of the fuel oil, increasing its value. Furthermore, during hydrocracking, the breaking of long-chain molecules removes sulfur, oxygen, and nitrogen, reducing the sulfur and aromatic hydrocarbon content of the fuel oil and thus decreasing harmful gas emissions during combustion, reducing environmental pollution. The obtained hydrocracking products are fractionated to obtain hydrocracking tail oil, hydrocracking gasoline fraction, and hydrocracking diesel fraction. The hydrocracking diesel fraction, with an initial boiling point of 160–180℃ and a final boiling point of 280–350℃, is then fed into a distillation column for further distillation.

[0029] It should be noted that the hydrocracking diesel fraction with an initial boiling point of 160–180℃ and a final boiling point of 280–350℃ is sent for rectification to produce fuel oil because this section of diesel fraction has a moderate flash point, which improves the combustion performance and stability of the fuel oil, and also helps reduce energy consumption in subsequent processes. If the final boiling point of the hydrocracking diesel fraction is higher than 350℃, the product will have a high flash point, resulting in incomplete combustion and more ash content after combustion. If the initial boiling point of the hydrorefined diesel fraction is lower than 160℃, the product's flash point will decrease, posing safety hazards for transportation and use. The hydrocracking gasoline fraction mainly contains light components such as naphtha, which can be used to produce gasoline. The hydrocracking tail oil mainly contains long-chain alkanes, which can be used to produce lubricating oil base oils.

[0030] After the above diesel fraction is refined, the following components are obtained: gasoline component at the top of the distillation column, first fuel oil component from the distillation column side stream, second fuel oil component from the distillation column side stream, and first coal-based Fischer-Tropsch synthetic fuel oil. The component at the top of the distillation column is mainly rich in light diesel oil and can be used to produce diesel products such as automotive diesel. The first coal-based Fischer-Tropsch synthetic fuel oil, with an initial boiling point of 220–240℃ and a final boiling point of 300–320℃, is mainly composed of alkanes and, when used as fuel oil, has advantages such as high calorific value, safety, stability, and cleanliness.

[0031] To fully separate alkane components with different boiling points and meet market demand for fuel oils with varying flash points, the intermediate product from the distillation column is separated into two groups: a first fuel oil component from the distillation column side stream and a second fuel oil component from the distillation column side stream. The first fuel oil component from the distillation column side stream has an initial boiling point of 120–160°C and a final boiling point of 230–250°C, and its main component is alkanes. Further fractionation yields a second coal-based Fischer-Tropsch synthetic fuel oil with an initial boiling point of 130–150°C and a final boiling point of 180–200°C. This fuel oil exhibits good combustion performance and stable safety characteristics. If the final boiling point of the second coal-based Fischer-Tropsch synthetic fuel oil is higher than 200°C, the product has a high flash point, is difficult to ignite, and burns incompletely. If the initial boiling point of the second coal-based Fischer-Tropsch synthetic fuel oil is lower than 130°C, the product has a low flash point, is easily ignited, and is unsafe.

[0032] The second fuel oil component in the distillation column side stream has an initial boiling point of 130–160℃ and a final boiling point of 250–275℃, and its main component is alkanes. Further fractionation yields the third coal-based Fischer-Tropsch synthetic fuel oil, with an initial boiling point of 170–190℃ and a final boiling point of 210–230℃. If the final boiling point of the third coal-based Fischer-Tropsch synthetic fuel oil is higher than 230℃, the product has a high flash point, which may lead to difficulty in ignition and incomplete combustion. If the initial boiling point of the third coal-based Fischer-Tropsch synthetic fuel oil is lower than 170℃, the product has a low flash point, is easily ignited, and has poor safety.

[0033] In summary, coal undergoes indirect liquefaction, Fischer-Tropsch synthesis, fractionation, hydrorefining, hydrocracking, and further fractionation to produce fuel oil with a total boiling point range of 170–320℃. This process is simple, has low requirements for raw materials, and produces high-quality products. The fuel oil has low sulfur, nitrogen, and aromatic hydrocarbon content, low acid value, and low ash content, making it a clean and environmentally friendly alternative to furnace fuel oil. Using coal as a raw material is abundant and widely available, effectively addressing the shortage of raw material resources for fuel oil in existing technologies.

[0034] To more fully prepare clean and stable qualified oil products from raw coal, in a preferred embodiment, step S1 of the Fischer-Tropsch synthesis crude oil preparation step involves: gasifying the coal to obtain syngas, and then subjecting the syngas to a Fischer-Tropsch synthesis reaction to prepare Fischer-Tropsch synthesis crude oil; wherein the syngas comprises H2 and CO in a molar ratio of (1.3–1.9):1; preferably, the gasification reaction temperature is 1200–1750°C; and / or the reaction pressure is 3–5 MPa; and / or the coal includes one or more of lignite, bituminous coal, and anthracite; and / or the catalyst for the Fischer-Tropsch synthesis reaction includes one or more of Fe-based catalysts, Co-based catalysts, Ni-based catalysts, and Ru-based catalysts. Under these conditions, using coal instead of petroleum as raw material can significantly reduce dependence on traditional petroleum resources, more fully promote the transformation of my country's energy structure, and result in higher yield and better quality Fischer-Tropsch synthesis crude oil.

[0035] In order to more thoroughly remove light oil from crude oil, thereby increasing the load of subsequent processing steps and further improving the production efficiency of subsequent fuel oil, in a preferred embodiment, in step S1, the first fractionation is carried out in a first fractionation tower, the bottom temperature of the first fractionation tower is 300-350°C, and the top pressure is 0.1-0.2 MPa.

[0036] To further reduce the occurrence of side reactions such as condensation, decarbonization, and methanation, thereby more effectively increasing the yield of alkane products and further improving the reaction rate of hydrorefining, in a preferred embodiment, in step S2, the reaction temperature of hydrorefining is 250–350°C, preferably 260–300°C; and / or the reaction pressure is 2–8 MPa, preferably 3–6 MPa; and / or the volume hourly space velocity is 0.5–3 h⁻¹. -1 Preferably 0.5 to 2 hours -1 The hydrogen-to-oil ratio is 200–700, preferably 250–400.

[0037] To further improve the selectivity of alkane products and the reaction rate of hydrorefining, in a preferred embodiment, the hydrorefining catalyst comprises a first support and a first active metal component supported on the first support; preferably, the mass ratio of the first active metal component to the first support is (3-8):1000; and / or the first support is one or more of silicon oxide, alumina, and titanium oxide, more preferably alumina; and / or the first active metal component comprises one or more of Co, Pt, Pd, Ni, W, and Mo, more preferably Mo-Ni. Under the above conditions, the catalyst has better activity, higher stability, better selectivity for alkane products, and can obtain more saturated hydrorefined products, which is more conducive to obtaining fuel oil with higher combustion performance.

[0038] To remove light oil components such as naphtha produced during hydrorefining and simultaneously obtain heavy oil components, in a preferred embodiment, the second fractionation is carried out in a second fractionation tower. The bottom temperature of the second fractionation tower is 280–350°C, preferably 310–340°C; and / or the top temperature is 100–145°C, preferably 100–130°C; and / or the bottom pressure is 0.1–1.1 MPa, preferably 0.2–0.6 MPa. Under these conditions, the product at the top of the second fractionation tower is gasoline fraction, the product at the bottom is hydrorefining tail oil, and the side stream component is diesel fraction, which is more conducive to obtaining fuel oil with better combustion performance.

[0039] To further improve the rates of alkane cracking, isomerization, and ring-opening cracking of polycyclic alkanes and polycyclic aromatic hydrocarbons in hydrocracking, and to more effectively prevent severe cracking, thereby more fully improving the selectivity and yield of diesel components, in a preferred embodiment, in step S3, the hydrocracking reaction temperature is 300–380°C, preferably 300–350°C; and / or the reaction pressure is 2–8 MPa, preferably 3–7 MPa; and / or the volume hourly space velocity is 0.5–3.5 h⁻¹. -1 Preferably, it is 0.5 to 1.5 hours. -1 The hydrogen-to-oil ratio is 200–800, preferably 200–500.

[0040] To achieve higher selectivity, higher yield, and higher diesel fraction production in hydrocracking products, while minimizing impurities such as polycyclic aromatic hydrocarbons, sulfur, and nitrogen, a preferred embodiment of the hydrocracking catalyst comprises a second support and a second active metal component supported on the second support. Preferably, the mass ratio of the second active metal component to the second support is (2-7):1000; and / or the second support is one or more of silicon oxide, alumina, and titanium oxide, more preferably alumina; and / or the second active metal component comprises one or more of Co, Pt, Pd, Ni, W, and Mo, more preferably Mo-Ni-W. Under these conditions, the selectivity for diesel fraction products is better, resulting in more stable hydrocracking products and a more favorable environment for obtaining fuel oil with higher and more stable combustion performance.

[0041] To more effectively remove light oil components such as naphtha produced by hydrocracking, while simultaneously obtaining heavy oil components, in a preferred embodiment, the third fractionation is carried out in a third fractionation tower. The bottom temperature of the third fractionation tower is 290–360°C, preferably 300–335°C; and / or the top temperature is 100–160°C, preferably 100–140°C; and / or the bottom pressure is 0.1–1.2 MPa, preferably 0.1–0.6 MPa. Under these conditions, the product at the top of the third fractionation tower is gasoline component, the product at the bottom is cracked tail oil, and the side stream component is cracked diesel oil, which is more conducive to obtaining fuel oil with better combustion performance.

[0042] In a preferred embodiment, in step S4, the hydrorefined diesel fraction and the hydrocracking diesel fraction are first mixed, and then distilled in the same distillation column; preferably, the mass ratio of the hydrorefined diesel fraction and the hydrocracking diesel fraction is (1-50):1; and / or the hydrorefined diesel fraction and the hydrocracking diesel fraction are distilled in the same distillation column with a switching feed method; preferably, the mass ratio of the hydrorefined diesel fraction and the hydrocracking diesel fraction is (1-50):1; and / or the hydrorefined diesel fraction and the hydrocracking diesel fraction are fed into different distillation columns with independent feed methods for distillation.

[0043] To more fully separate and divide the oil fractions from different sections of the diesel distillate, in a preferred embodiment, in step S4, the top temperature of the distillation column is 70–110°C, preferably 90°C; and / or the bottom temperature is 200–280°C, preferably 240°C; and / or the top pressure is 15–25 kPa, preferably 20 kPa. Under these conditions, the product at the top of the distillation column is light diesel oil, the product at the bottom is coal-based fuel oil, and the side stream component is diesel oil with a suitable distillation range, which is more conducive to obtaining fuel oil with better combustion performance.

[0044] For the purpose of more easily obtaining fuel oil with a specific distillation range, in a preferred embodiment, in step S5, the fourth fractionation is carried out in the first side-stream column, the bottom temperature of the first side-stream column is 140-190°C; and / or the top temperature is 50-90°C; and / or the bottom pressure is 0.1-1 MPa; and / or the fifth fractionation is carried out in the second side-stream column, the bottom temperature of the second side-stream column is 180-220°C; and / or the top temperature is 80-100°C; and / or the bottom pressure is 0.1-1 MPa.

[0045] In another typical embodiment of the present invention, a coal-based Fischer-Tropsch synthetic fuel oil is also provided, which is prepared by the above-described preparation method. Compared with petroleum-based fuel oil, the coal-based Fischer-Tropsch synthetic fuel oil of the present invention has lower sulfur and nitrogen content, lower acid value, and lower ash content. Moreover, it has abundant and widely available raw material resources, making it a clean and environmentally friendly alternative to furnace fuel oil. It can effectively solve the problems of high sulfur content, uncleanliness, and shortage of raw material resources in existing fuel oils.

[0046] In yet another typical embodiment of the present invention, the application of the above-mentioned coal-based Fischer-Tropsch synthetic fuel oil in domestic and / or industrial burners is also provided.

[0047] The present application will be further described in detail below with reference to specific embodiments, which should not be construed as limiting the scope of protection claimed in the present application.

[0048] Example 1

[0049] A schematic diagram of the process for preparing coal-based Fischer-Tropsch synthetic fuel oil is shown below. Figure 1 Step S1: In the Fischer-Tropsch reactor 1 of the coal indirect liquefaction process, raw material A (specifically lignite) is gasified at 1450℃ and 4MPa to obtain syngas (the molar ratio of H2 to CO is 1.75:1). Under the action of a slurry bed Fischer-Tropsch synthesis catalyst (iron-based catalyst), the syngas undergoes a Fischer-Tropsch synthesis reaction to obtain Fischer-Tropsch crude oil B. The Fischer-Tropsch crude oil is sent to the first fractionation tower 2 for the first fractionation. The bottom temperature of the first fractionation tower is 325℃ and the top pressure is 0.15MPa. The top of the tower yields the first oil fraction C (mainly naphtha) with a boiling point <190℃, which can be used to prepare gasoline. The bottom of the tower yields Fischer-Tropsch stabilized heavy oil D.

[0050] Step S2: Fischer-Tropsch stabilized heavy oil D is fed into hydrorefining reactor 3, and the reaction is carried out at a temperature of 280°C, a pressure of 4.5 MPa, and a volume hourly space velocity of 1.2 h⁻¹. -1 Under the conditions of a hydrogen-to-oil ratio of 300 and a catalyst consisting of an alumina support loaded with Mo-Ni active metal components (where the mass ratio of active components to support is 5:1000), hydrorefining is carried out to obtain hydrorefined product E. Hydrorefined product E is fed into a second fractionating column 4 for second fractionation. The bottom temperature of the second fractionating column is 325℃, the top temperature is 120℃, and the bottom pressure is 0.4MPa. The top of the second fractionating column yields hydrorefined gasoline fraction F with a boiling point <190℃, which can be used to prepare qualified gasoline products. The side stream yields hydrorefined diesel fraction G with an initial boiling point of 165℃ and a final boiling point of 320℃. The bottom of the column yields hydrorefined tail oil H with a boiling point >350℃.

[0051] Step S3: The hydrorefined tail oil H is fed into the hydrocracking reactor 5, and the reaction is carried out at a temperature of 325°C, a pressure of 5 MPa, and a volume hourly space velocity of 1 h⁻¹. -1 Under the conditions of a hydrogen-to-oil ratio of 350 and a catalyst supported on an alumina carrier with Mo-Ni-W active metal components (where the mass ratio of active components to carrier is 4:1000), hydrocracking is carried out to obtain hydrocracking product I. Hydrocracking product I is fed into the third fractionation column 6 for third fractionation. The bottom temperature of the third fractionation column is 310℃, the top temperature is 125℃, and the bottom pressure is 0.35MPa. The top of the third fractionation column yields hydrocracking gasoline fraction J with a boiling point <190℃, which can be used to prepare qualified gasoline products. The side stream yields hydrocracking diesel fraction K with an initial boiling point of 170℃ and a final boiling point of 300℃. The bottom of the column yields hydrocracking tail oil L with a boiling point >345℃, which can be used to prepare lubricating oil and other products.

[0052] In step S4, the hydrotreated diesel fraction G and the hydrocracking diesel fraction K are fed into storage tank 7 for mixing. The mass ratio of the hydrotreated diesel fraction to the hydrocracking diesel fraction is 1:1, resulting in a mixed fraction M. The mixed fraction M is then fed into distillation column 9 via feed pump 8 for distillation. The top temperature of the distillation column is 90°C, the bottom temperature is 240°C, and the top pressure is 20 kPa. The top of the distillation column yields a second oil fraction N (mainly composed of light diesel oil) with a boiling point <180°C, which can be used to prepare synthetic diesel products, etc. The side stream yields a first fuel oil component O with an initial boiling point of 140°C and a final boiling point of 240°C, and a second fuel oil component P with an initial boiling point of 150°C and a final boiling point of 260°C. The bottom of the column yields a first coal-based Fischer-Tropsch synthetic fuel oil Q with an initial boiling point of 230°C and a final boiling point of 310°C.

[0053] In step S5, the first fuel oil component O from the distillation column side stream is fed into the first side stream column 10 for fourth fractionation. The bottom temperature of the first side stream column is 165°C, the top temperature is 75°C, and the bottom pressure is 0.5 MPa. The top of the column yields a third oil fraction R (mainly light diesel oil) with a boiling point <180°C, which can be used to prepare diesel products. The bottom of the column yields a second coal-based Fischer-Tropsch synthetic fuel oil S with an initial boiling point of 180°C and a final boiling point of 240°C. The second fuel oil component P from the distillation column side stream is fed into the second side stream column 11 for fifth fractionation. The bottom temperature of the second side stream column is 200°C, the top temperature is 95°C, and the bottom pressure is 0.6 MPa. The top of the column yields a fourth oil fraction T (mainly light diesel oil) with a boiling point <200°C, which can be used to prepare diesel products. The bottom of the column yields a third coal-based Fischer-Tropsch synthetic fuel oil U with an initial boiling point of 235°C and a final boiling point of 265°C.

[0054] The first coal-based Fischer-Tropsch synthetic fuel oil Q, the second coal-based Fischer-Tropsch synthetic fuel oil S, and the third coal-based Fischer-Tropsch synthetic fuel oil U can be used in burners and / or industrial burners, respectively.

[0055] The physicochemical properties of the first, second, and third coal-based Fischer-Tropsch synthetic fuel oils prepared are shown in Table 1.

[0056] Example 2

[0057] The only difference from Example 1 is:

[0058] In step S1, the raw material is bituminous coal; the molar ratio of H2 to CO in the syngas is 1.3:1; the reaction temperature of coal gasification is 1200℃; the reaction pressure is 5MPa; the catalyst for the Fischer-Tropsch synthesis reaction is an Fe-based catalyst; the bottom temperature of the first fractionation column is 350℃, the top pressure is 0.1MPa, the first oil fraction with a boiling point <185℃ is obtained at the top of the column, and the Fischer-Tropsch stabilized heavy oil is obtained at the bottom of the column.

[0059] The physicochemical properties of the first, second, and third coal-based Fischer-Tropsch synthetic fuel oils prepared are shown in Table 2.

[0060] Example 3

[0061] The only difference from Example 1 is:

[0062] In step S1, the raw material is bituminous coal; the molar ratio of H2 to CO in the syngas is 1.9:1; the reaction temperature of coal gasification is 1750℃; the reaction pressure is 3MPa; the catalyst for the Fischer-Tropsch synthesis reaction is a Co-based catalyst; the bottom temperature of the first fractionation column is 300℃, the top pressure is 0.2MPa, the first oil fraction with a boiling point <190℃ is obtained at the top of the column, and the Fischer-Tropsch stabilized heavy oil is obtained at the bottom of the column.

[0063] The physicochemical properties of the first, second, and third coal-based Fischer-Tropsch synthetic fuel oils prepared are shown in Table 3.

[0064] Example 4

[0065] The only difference from Example 1 is:

[0066] In step S2, the reaction temperature is 260℃, the reaction pressure is 6MPa, and the volume hourly space velocity is 0.5h. -1 Hydrorefining is carried out under the conditions of a hydrogen-to-oil ratio of 250 and a catalyst consisting of a silica support loaded with Co active metal components (where the mass ratio of active components to support is 3:1000). The bottom temperature of the second fractionation column is 310℃, the top temperature is 100℃, and the bottom pressure is 0.2MPa. The top of the second fractionation column yields a hydrorefined gasoline fraction with a boiling point <190℃, the side stream yields a hydrorefined diesel fraction with an initial boiling point of 170℃ and a final boiling point of 320℃, and the bottom of the column yields a hydrorefined tail oil with a boiling point >355℃.

[0067] The physicochemical properties of the first, second, and third coal-based Fischer-Tropsch synthetic fuel oils prepared are shown in Table 4.

[0068] Example 5

[0069] The only difference from Example 1 is:

[0070] In step S2, the reaction temperature is 300℃, the reaction pressure is 3MPa, and the volume hourly space velocity is 2h. -1Hydrorefining is carried out under the conditions of a hydrogen-to-oil ratio of 400 and a catalyst consisting of a silica support loaded with Co active metal components (where the mass ratio of active components to support is 8:1000). The bottom temperature of the second fractionation column is 340℃, the top temperature is 130℃, and the bottom pressure is 0.6MPa. The top of the second fractionation column yields a hydrorefined gasoline fraction with a boiling point <185℃, the side stream yields a hydrorefined diesel fraction with an initial boiling point of 160℃ and a final boiling point of 330℃, and the bottom of the column yields a hydrorefined tail oil with a boiling point >350℃.

[0071] The physicochemical properties of the first, second, and third coal-based Fischer-Tropsch synthetic fuel oils prepared are shown in Table 5.

[0072] Example 6

[0073] The only difference from Example 1 is:

[0074] In step S2, the reaction temperature is 250℃, the reaction pressure is 8MPa, and the volume hourly space velocity is 0.5h. -1 Hydrorefining was carried out under the conditions of a hydrogen-to-oil ratio of 700 and a catalyst consisting of a titanium dioxide support loaded with Co active metal components (where the mass ratio of active components to support is 5:1000). The bottom temperature of the second fractionation column was 280℃, the top temperature was 145℃, and the bottom pressure was 0.1MPa. The top of the second fractionation column yielded a hydrorefined gasoline fraction with a boiling point <190℃, the side stream yielded a hydrorefined diesel fraction with an initial boiling point of 175℃ and a final boiling point of 325℃, and the bottom of the column yielded a hydrorefined tail oil with a boiling point >360℃.

[0075] The physicochemical properties of the first, second, and third coal-based Fischer-Tropsch synthetic fuel oils prepared are shown in Table 6.

[0076] Example 7

[0077] The only difference from Example 1 is:

[0078] In step S2, the reaction temperature is 350℃, the reaction pressure is 2MPa, and the volume hourly space velocity is 3h. -1 Hydrorefining is carried out under the conditions of a hydrogen-to-oil ratio of 200 and a catalyst consisting of a titanium oxide support loaded with Co-containing metal components (where the mass ratio of active component to support is 5:1000). The bottom temperature of the second fractionation column is 350℃, the top temperature is 100℃, and the bottom pressure is 1.1MPa. The top of the second fractionation column yields a hydrorefined gasoline fraction with a boiling point <190℃, the side stream yields a hydrorefined diesel fraction with an initial boiling point of 170℃ and a final boiling point of 345℃, and the bottom of the column yields a hydrorefined tail oil with a boiling point >360℃.

[0079] The physicochemical properties of the first, second, and third coal-based Fischer-Tropsch synthetic fuel oils prepared are shown in Table 7.

[0080] Example 8

[0081] The only difference from Example 1 is:

[0082] In step S3, the reaction temperature is 300℃, the reaction pressure is 7MPa, and the volume hourly space velocity is 0.5h. -1 Hydrocracking was carried out under the conditions of a hydrogen-to-oil ratio of 500 and a catalyst consisting of a silica support loaded with Pt active metal components (where the mass ratio of active components to support is 4:1000). The bottom temperature of the third fractionation column was 300℃, the top temperature was 140℃, and the bottom pressure was 0.1MPa. The top of the third fractionation column yielded a hydrocracking gasoline fraction with a boiling point <196℃, the side stream yielded a hydrocracking diesel fraction with an initial boiling point of 172℃ and a final boiling point of 346℃, and the bottom of the column yielded a hydrocracking tail oil with a boiling point >350℃.

[0083] The physicochemical properties of the first, second, and third coal-based Fischer-Tropsch synthetic fuel oils prepared are shown in Table 8.

[0084] Example 9

[0085] The only difference from Example 1 is:

[0086] In step S3, the reaction temperature is 350℃, the reaction pressure is 3MPa, and the volume hourly space velocity is 1.5h. -1 Hydrocracking was carried out under the conditions of a hydrogen-to-oil ratio of 200 and a catalyst consisting of a silica support loaded with Pt active metal components (where the mass ratio of active components to support is 4:1000). The bottom temperature of the third fractionation column was 335℃, the top temperature was 100℃, and the bottom pressure was 0.6MPa. The top of the third fractionation column yielded a hydrocracking gasoline fraction with a boiling point <192℃, the side stream yielded a hydrocracking diesel fraction with an initial boiling point of 176℃ and a final boiling point of 345℃, and the bottom of the column yielded a hydrocracking tail oil with a boiling point >353℃.

[0087] The physicochemical properties of the first, second, and third coal-based Fischer-Tropsch synthetic fuel oils prepared are shown in Table 9.

[0088] Example 10

[0089] The only difference from Example 1 is:

[0090] In step S3, the reaction temperature is 300℃, the reaction pressure is 8MPa, and the volume hourly space velocity is 0.5h. -1Hydrocracking was carried out under the conditions of a hydrogen-to-oil ratio of 800 and a catalyst consisting of a silicon oxide support loaded with Pd active metal components (where the mass ratio of active components to support is 2:1000). The bottom temperature of the third fractionation column was 290℃, the top temperature was 160℃, and the bottom pressure was 0.1MPa. The top of the third fractionation column yielded a hydrocracking gasoline fraction with a boiling point <190℃, the side stream yielded a hydrocracking diesel fraction with an initial boiling point of 178℃ and a final boiling point of 348℃, and the bottom of the column yielded a hydrocracking tail oil with a boiling point >355℃.

[0091] The physicochemical properties of the first, second, and third coal-based Fischer-Tropsch synthetic fuel oils prepared are shown in Table 10.

[0092] Example 11

[0093] The only difference from Example 1 is:

[0094] In step S3, the reaction temperature is 380℃, the reaction pressure is 2MPa, and the volume hourly space velocity is 3.5h. -1 Hydrocracking was carried out under the conditions of a hydrogen-to-oil ratio of 200 and a catalyst consisting of a silicon oxide support loaded with Pd active metal components (where the mass ratio of active components to support is 7:1000). The bottom temperature of the third fractionation column was 360℃, the top temperature was 100℃, and the bottom pressure was 1.2MPa. The top of the third fractionation column yielded a hydrocracking gasoline fraction with a boiling point <195℃, the side stream yielded a hydrocracking diesel fraction with an initial boiling point of 180℃ and a final boiling point of 350℃, and the bottom of the column yielded a hydrocracking tail oil with a boiling point >358℃.

[0095] The physicochemical properties of the first, second, and third coal-based Fischer-Tropsch synthetic fuel oils prepared are shown in Table 11.

[0096] Example 12

[0097] The only difference from Example 1 is:

[0098] In step S4, the mass ratio of hydrorefined diesel fraction to hydrocracking diesel fraction is 50:1. The top temperature of the distillation column is 70°C, the bottom temperature is 280°C, and the top pressure is 15 kPa. The top of the distillation column yields a second oil fraction with a boiling point <160°C. The side stream yields a first fuel oil component with an initial boiling point of 160°C and a final boiling point of 235°C, and a second fuel oil component with an initial boiling point of 160°C and a final boiling point of 255°C. The bottom of the column yields a first coal-based Fischer-Tropsch synthetic fuel oil with an initial boiling point of 225°C and a final boiling point of 305°C.

[0099] The physicochemical properties of the first, second, and third coal-based Fischer-Tropsch synthetic fuel oils prepared are shown in Table 12.

[0100] Example 13

[0101] The only difference from Example 1 is:

[0102] In step S4, the mass ratio of hydrorefined diesel fraction to hydrocracking diesel fraction is 1:50. The top temperature of the distillation column is 110℃, the bottom temperature is 200℃, and the top pressure is 25kPa. The top of the distillation column yields a second oil fraction with a boiling point <155℃. The side stream yields a first fuel oil component with an initial boiling point of 155℃ and a final boiling point of 245℃, and a second fuel oil component with an initial boiling point of 160℃ and a final boiling point of 270℃. The bottom of the column yields a first coal-based Fischer-Tropsch synthetic fuel oil with an initial boiling point of 235℃ and a final boiling point of 315℃.

[0103] The physicochemical properties of the first, second, and third coal-based Fischer-Tropsch synthetic fuel oils prepared are shown in Table 13.

[0104] Example 14

[0105] The only difference from Example 1 is:

[0106] In step S4, the hydrorefined diesel fraction and the hydrocracking diesel fraction are distilled in the same distillation column using a switching feed method. Specifically, switching feed means that after feeding the hydrorefined diesel fraction for 1 hour, the feed is stopped, and then the hydrocracking diesel fraction is fed for 1 hour, and so on without interruption. The mass ratio of the hydrorefined diesel fraction and the hydrocracking diesel fraction is 1:1. The top of the distillation column yields a second oil fraction with a boiling point <160℃, the side stream yields a first fuel oil component with an initial boiling point of 160℃ and a final boiling point of 238℃, and a second fuel oil component with an initial boiling point of 160℃ and a final boiling point of 260℃, and the bottom of the column yields a first coal-based Fischer-Tropsch synthetic fuel oil with an initial boiling point of 228℃ and a final boiling point of 309℃.

[0107] The physicochemical properties of the first, second, and third coal-based Fischer-Tropsch synthetic fuel oils prepared are shown in Table 14.

[0108] Example 15

[0109] The only difference from Example 1 is:

[0110] In step S4, the hydrorefined diesel fraction and the hydrocracking diesel fraction are fed into different distillation columns separately using an independent feed method. Specifically, independent feed means that only the hydrorefined diesel fraction or the hydrocracking diesel fraction is fed in within one cycle. The top of the two distillation columns yields a second oil fraction with a boiling point <160℃, the side streams yield a first fuel oil component with an initial boiling point of 160℃ and a final boiling point of 237℃, the side streams yield a second fuel oil component with an initial boiling point of 153℃ and a final boiling point of 260℃, and the bottom of the columns yields a first coal-based Fischer-Tropsch synthetic fuel oil with an initial boiling point of 232℃ and a final boiling point of 313℃.

[0111] The physicochemical properties of the first, second, and third coal-based Fischer-Tropsch synthetic fuel oils prepared are shown in Table 15.

[0112] Example 16

[0113] The only difference from Example 1 is:

[0114] In step S5, the bottom temperature of the first side-stream tower is 140℃, the top temperature is 50℃, and the bottom pressure is 1MPa. A third oil fraction with a boiling point <180℃ is obtained at the top of the tower, and a second coal-based Fischer-Tropsch synthetic fuel oil with an initial boiling point of 178℃ and a final boiling point of 242℃ is obtained at the bottom of the tower. The bottom temperature of the second side-stream tower is 220℃, the top temperature is 100℃, and the bottom pressure is 0.1MPa. A fourth oil fraction with a boiling point <185℃ is obtained at the top of the tower, and a third coal-based Fischer-Tropsch synthetic fuel oil with an initial boiling point of 232℃ and a final boiling point of 262℃ is obtained at the bottom of the tower.

[0115] The physicochemical properties of the first, second, and third coal-based Fischer-Tropsch synthetic fuel oils prepared are shown in Table 16.

[0116] Example 17

[0117] The only difference from Example 1 is:

[0118] In step S5, the bottom temperature of the first side-stream tower is 190℃, the top temperature is 90℃, and the bottom pressure is 0.1MPa. A third oil fraction with a boiling point <185℃ is obtained at the top of the tower, and a second coal-based Fischer-Tropsch synthetic fuel oil with an initial boiling point of 183℃ and a final boiling point of 247℃ is obtained at the bottom of the tower. The bottom temperature of the second side-stream tower is 180℃, the top temperature is 80℃, and the bottom pressure is 1MPa. A fourth oil fraction with a boiling point <190℃ is obtained at the top of the tower, and a third coal-based Fischer-Tropsch synthetic fuel oil with an initial boiling point of 238℃ and a final boiling point of 258℃ is obtained at the bottom of the tower.

[0119] The physicochemical properties of the first, second, and third coal-based Fischer-Tropsch synthetic fuel oils prepared are shown in Table 17.

[0120] Test method:

[0121] Flash point: Tested according to GB / T 261-2021.

[0122] Kinematic viscosity: Tested according to GB / T 265-1988.

[0123] Aromatic hydrocarbon content: Tested in accordance with NB / SH / T 0913-2015.

[0124] Pour point: Tested according to GB / T 3535-2006.

[0125] Color: Tested in accordance with GB / T 3555-2006.

[0126] Copper sheet corrosion: Tested according to GB / T 5096-2017.

[0127] Bromine index: Tested according to SH / T 0630-1996.

[0128] Table 1

[0129]

[0130]

[0131] Table 2

[0132]

[0133] Table 3

[0134]

[0135] Table 4

[0136]

[0137]

[0138] Table 5

[0139]

[0140] Table 6

[0141]

[0142]

[0143] Table 7

[0144]

[0145] Table 8

[0146]

[0147]

[0148] Table 9

[0149]

[0150] Table 10

[0151]

[0152]

[0153] Table 11

[0154]

[0155] Table 12

[0156]

[0157]

[0158] Table 13

[0159]

[0160] Table 14

[0161]

[0162]

[0163] Table 15

[0164]

[0165] Table 16

[0166]

[0167] Table 17

[0168]

[0169]

[0170] As can be seen from the above, this invention prepares three types of fuel oil by fractionating, hydrorefining, hydrocracking, and fractionating crude oil from indirect coal liquefaction Fischer-Tropsch synthesis. Compared with petroleum-based fuel oil, coal-based Fischer-Tropsch synthesis fuel oil has lower sulfur and nitrogen content, lower acid value, and lower ash content, making it a clean and environmentally friendly alternative to furnace fuel oil.

[0171] It can be seen that when all process parameters are within the preferred range of this invention, coal-based Fischer-Tropsch synthetic fuel oil has lower sulfur and nitrogen content, lower acid value, and less ash content.

[0172] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing coal-based Fischer-Tropsch synthetic fuel oil, characterized in that, The preparation method includes the following steps: Step S1: Using coal as raw material, Fischer-Tropsch synthesis crude oil is prepared through coal indirect liquefaction Fischer-Tropsch synthesis reaction. The Fischer-Tropsch synthesis crude oil is then subjected to a first fractionation to obtain Fischer-Tropsch stabilized heavy oil. Step S2: Hydrorefining the Fischer-Tropsch stabilized heavy oil to obtain a hydrorefined product; and performing a second fractionation on the hydrorefined product to obtain a hydrorefined diesel fraction, a hydrorefined tail oil, and a hydrorefined gasoline fraction with a boiling point <195℃. Step S3: The hydrorefined tail oil is subjected to hydrocracking to obtain hydrocracking products; the hydrocracking products are subjected to third fractionation to obtain hydrocracking tail oil, hydrocracking gasoline fraction and hydrocracking diesel fraction; wherein the initial boiling point of the hydrocracking diesel fraction is 160~180℃ and the final boiling point is 280~350℃. Step S4: The hydrotreated diesel fraction and the hydrocracking diesel fraction are fed into a distillation column for distillation to obtain a light diesel component from the top of the distillation column, a first fuel oil component from the distillation column side stream, a second fuel oil component from the distillation column side stream, and a first coal-based Fischer-Tropsch synthetic fuel oil. The first fuel oil component from the distillation column side stream has an initial boiling point of 120-160°C and a final boiling point of 230-250°C; the second fuel oil component from the distillation column side stream has an initial boiling point of 130-160°C and a final boiling point of 250-275°C; and the first coal-based Fischer-Tropsch synthetic fuel oil has an initial boiling point of 220-240°C and a final boiling point of 300-320°C. Step S5: The first fuel oil component from the distillation column side stream is subjected to a fourth fractionation to obtain a second coal-based Fischer-Tropsch synthetic fuel oil; the second fuel oil component from the distillation column side stream is subjected to a fifth fractionation to obtain a third coal-based Fischer-Tropsch synthetic fuel oil; wherein the initial boiling point of the second coal-based Fischer-Tropsch synthetic fuel oil is 170~195℃ and the final boiling point is 230~250℃, and the initial boiling point of the third coal-based Fischer-Tropsch synthetic fuel oil is 225~245℃ and the final boiling point is 250~275℃.

2. The preparation method according to claim 1, characterized in that, In step S1 The preparation steps of the Fischer-Tropsch crude oil are as follows: coal is gasified to obtain syngas, and the syngas is subjected to a Fischer-Tropsch synthesis reaction to prepare the Fischer-Tropsch crude oil; wherein the syngas includes H2 and CO, and the molar ratio of the two is (1.3~1.9):

1.

3. The preparation method according to claim 2, characterized in that, The gasification reaction temperature is 1200~1750℃; and / or the reaction pressure is 3~5MPa; and / or The coal includes one or more of lignite, bituminous coal, and anthracite; and / or The catalyst for the Fischer-Tropsch synthesis reaction includes one or more of Fe-based, Co-based, Ni-based, and Ru-based catalysts.

4. The preparation method according to any one of claims 1 to 3, characterized in that, In step S1 The first fractionation is carried out in a first fractionation column, where the bottom temperature of the first fractionation column is 300~350℃ and the top pressure is 0.1~0.2MPa.

5. The preparation method according to any one of claims 1 to 3, characterized in that, In step S2 The hydrorefining reaction temperature is 250~350℃; and / or the reaction pressure is 2~8MPa; and / or the volume hourly space velocity is 0.5~3h. -1 ; and / or a hydrogen-to-oil ratio of 200-700; and / or The hydrorefining catalyst comprises a first support and a first active metal component supported on the first support; and / or the first support comprises one or more of silicon oxide, aluminum oxide, and titanium oxide; and / or the first active metal component comprises one or more of Co, Pt, Pd, Ni, W, and Mo; and / or The second fractionation is carried out in a second fractionation column, the bottom temperature of which is 280~350℃; and / or the top temperature of which is 100~145℃; and / or the bottom pressure of which is 0.1~1.1MPa.

6. The preparation method according to claim 5, characterized in that, The hydrorefining reaction temperature is 260~300℃; and / or the reaction pressure is 3~6MPa; and / or the volume hourly space velocity is 0.5~2h. -1 ; and / or the hydrogen-to-oil ratio is 250-400.

7. The preparation method according to claim 5, characterized in that, The mass ratio of the first active metal component to the first carrier is (3~8):1000.

8. The preparation method according to claim 5, characterized in that, The bottom temperature of the second fractionation column is 310~340℃; and / or the top temperature is 100~130℃; and / or the bottom pressure is 0.2~0.6MPa.

9. The preparation method according to any one of claims 1 to 3, characterized in that, In step S3 The hydrocracking reaction temperature is 300-380℃; and / or the reaction pressure is 2-8 MPa; and / or the volume hourly space velocity is 0.5-3.5 h⁻¹. -1 ; and / or a hydrogen-to-oil ratio of 200-800; and / or The hydrocracking catalyst comprises a second support and a second active metal component supported on the second support; and / or the second support comprises one or more of silicon oxide, alumina, and titanium oxide; and / or the second active metal component comprises one or more of Co, Pt, Pd, Ni, W, and Mo; and / or The third fractionation is carried out in a third fractionation column, where the bottom temperature of the third fractionation column is 290~360℃; and / or the top temperature is 100~160℃; and / or the bottom pressure is 0.1~1.2MPa.

10. The preparation method according to claim 9, characterized in that, The hydrocracking reaction temperature is 300-350°C; and / or the reaction pressure is 3-7 MPa; and / or the volume hourly space velocity is 0.5-1.5 h⁻¹. -1 ; and / or the hydrogen-to-oil ratio is 200-500.

11. The preparation method according to claim 9, characterized in that, The mass ratio of the second active metal component to the second carrier is (2~7):1000.

12. The preparation method according to claim 9, characterized in that, The bottom temperature of the third fractionation column is 300~335℃; and / or the top temperature is 100~140℃; and / or the bottom pressure is 0.1~0.6MPa.

13. The preparation method according to any one of claims 1 to 3, characterized in that, In step S4 The hydrorefined diesel fraction and the hydrocracking diesel fraction are first mixed, and then the distillation is carried out in the same distillation column; the mass ratio of the hydrorefined diesel fraction to the hydrocracking diesel fraction is (1~50):1; and / or The hydrotreated diesel fraction and the hydrocracking diesel fraction are distilled in the same distillation column with a switching feed method; the mass ratio of the hydrotreated diesel fraction to the hydrocracking diesel fraction is (1~50):1; and / or The hydrorefined diesel fraction and the hydrocracking diesel fraction are fed independently into different distillation columns for distillation.

14. The preparation method according to any one of claims 1 to 3, characterized in that, In step S4 The distillation column has a top temperature of 70-110°C; and / or a bottom temperature of 200-280°C; and / or a top pressure of 15-25 kPa.

15. The preparation method according to any one of claims 1 to 3, characterized in that, In step S5 The fourth fractionation is carried out in the first side-stream column, where the bottom temperature is 140~190℃; and / or the top temperature is 50~90℃; and / or the bottom pressure is 0.1~1MPa; and / or The fifth fractionation is carried out in the second side-stream column, where the bottom temperature of the second side-stream column is 180~220℃; and / or the top temperature is 80~100℃; and / or the bottom pressure is 0.1~1MPa.

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