Process for the preparation of coal-based hot gas engine fuel

Abstract

The application provides a preparation method of coal-based hot gas engine fuel. The method comprises the following steps: mixing coal direct liquefaction crude oil with hydrogen, sequentially performing hydrogenation stabilization reaction, first fractionation, hydrogenation refining reaction, hydrogenation cracking reaction and second fractionation to obtain a coal-based hot gas engine fuel component; and mixing the component with a lubricity additive to obtain the coal-based hot gas engine fuel; wherein the weight percentage content of aromatic hydrocarbons in the coal direct liquefaction crude oil is 70-85 wt.%, the content of sulfur atoms is 200-400 mg / kg, and the content of nitrogen atoms is 2000-4000 mg / kg. The coal direct liquefaction crude oil can be deeply removed of heteroatoms by the multi-stage hydrogenation process gradient control, high-content aromatic hydrocarbons can be saturated and converted, and the hot gas engine carbon deposition can be reduced, so that the equipment life can be prolonged, the low-temperature fluidity of the fuel can be improved, the fuel lubricity is strong, and the working requirements of the hot gas engine for stable combustion outside and efficient energy release can be met.

Description

Technical Field

[0001] This invention relates to the field of coal liquefaction for fuel production technology, and more specifically, to a method for preparing coal-based thermal engine fuel. Background Technology

[0002] Stirling engines are characterized by stable operation, low noise, and strong heat source adaptability. Their efficiency relies on the continuous and controllable release of heat from fuel, offering advantages such as quiet operation and independence from air. They are widely used power systems in various applications, including submarine AIP propulsion and other specialized equipment, as well as new energy power generation. Currently, Stirling engine fuels are primarily petroleum-based products, with complex preparation processes, limited cycloalkanes content, and little room for improvement in volumetric calorific value. The development of coal chemical technology has provided a foundation for the development of coal-based Stirling engine fuels. Coal-based fuels, as a new energy carrier, offer advantages such as abundant raw materials and high energy density potential. However, direct coal liquefaction crude oil generally suffers from high aromatic content and residual sulfur and nitrogen heteroatoms. Direct use of coal-based crude oil can lead to severe carbon buildup in Stirling engines, decreased operational stability, reduced equipment lifespan, and decreased combustion efficiency, failing to meet the stringent requirements of Stirling engine power systems.

[0003] Existing coal-based product preparation processes are mostly designed for conventional fuels and do not take into account the application scenarios of gas turbine fuels. The distillation range distribution of the products does not match the requirements of gas turbine fuels, and key distillation temperature indicators are difficult to meet. Therefore, based on the development of the coal liquefaction industry, developing coal-based fuels suitable for gas turbines is of great significance for improving coal energy utilization and enhancing equipment endurance. Summary of the Invention

[0004] The main objective of this invention is to provide a method for preparing coal-based gas turbine fuel, in order to solve the problems in the prior art where using crude oil from direct coal liquefaction as gas turbine fuel leads to severe carbon buildup in the gas turbine, reduced operational stability, and reduced equipment lifespan and combustion efficiency.

[0005] To achieve the above objectives, according to one aspect of the present invention, a method for preparing coal-based thermal engine fuel is provided, comprising the following steps: Step S1, mixing crude oil from direct coal liquefaction with hydrogen and performing a hydrogenation stabilization reaction to obtain hydrogenated stabilized oil, and subjecting the hydrogenated stabilized oil to a first fractionation to obtain stabilized distillate oil; Step S2, mixing the stabilized distillate oil with hydrogen and performing a hydrogenation refining reaction to obtain hydrogenated refined oil; Step S3, mixing the hydrogenated refined oil with hydrogen and performing a hydrogenation cracking reaction to obtain hydrogenated cracked oil, and subjecting the hydrogenated cracked oil to a second fractionation to obtain coal-based thermal engine fuel components; Step S4, mixing the coal-based thermal engine fuel components with a lubricating additive to obtain coal-based thermal engine fuel; wherein, the crude oil from direct coal liquefaction has an aromatic hydrocarbon content of 70-85 wt.%, a sulfur atom content of 200-400 mg / kg, and a nitrogen atom content of 2000-4000 mg / kg.

[0006] Furthermore, step S1 also includes the following steps: mixing coal with a solvent to obtain an oil-coal slurry, mixing the oil-coal slurry with hydrogen, and sequentially performing a direct coal liquefaction reaction and a third fractionation to obtain direct coal liquefaction crude oil and residue; and / or, the weight percentage of aromatics in the direct coal liquefaction crude oil is 70-80 wt.%, the sulfur content is 200-300 mg / kg, and the nitrogen content is 2000-3000 mg / kg.

[0007] Furthermore, in step S1, the hydrogenation stabilization reaction is carried out at a temperature of 330–390 °C, a pressure of 10–15 MPa, and a volume hourly space velocity of 0.8–2.5 h⁻¹. -1 The hydrogen-to-oil ratio is 600-1000 V / V; and / or, the lower limit of the temperature for the first fractionation is 200-260°C, preferably 220-250°C; and / or, the upper limit of the temperature for the first fractionation is 380-480°C, preferably 400-450°C; and / or, the weight percentage of aromatics in the stabilized distillate oil is 50-70 wt.%, the sulfur content is 10-50 mg / kg, and the nitrogen content is 1000-2000 mg / kg.

[0008] Furthermore, in step S2, the hydrogenation purification reaction is carried out at a temperature of 340–400 °C, a reaction pressure of 6.0–19.0 ​​MPa, and a volume hourly space velocity of 0.3–2.0 h⁻¹. -1 The hydrogen-to-oil ratio is 500~1500 V / V; preferably, the hydrogenation refining reaction temperature is 360~390℃, the reaction pressure is 12.0~17.0 MPa, and the volume hourly space velocity is 0.5~1.5 h⁻¹. -1 The hydrogen-to-oil ratio is 800~1000V / V.

[0009] Furthermore, in step S3, the hydrocracking reaction is carried out at a temperature of 330–400 °C, a reaction pressure of 8.0–19.0 ​​MPa, and a volume hourly space velocity of 1.0–4.0 h⁻¹. -1 The hydrogen-to-oil ratio is 500~1500 V / V; preferably, the hydrocracking reaction temperature is 350~380℃; the reaction pressure is 10~15 MPa; and the volume hourly space velocity is 1.5~2.0 h⁻¹. -1 The hydrogen-to-oil ratio is 800-1000 V / V; and / or, the lower limit of the temperature for the second fractionation is 240-260°C, and the upper limit is 300-350°C.

[0010] Furthermore, in step S1, the hydrogenation stabilization reaction also uses a hydrogenation stabilization catalyst; and / or, in step S2, the hydrogenation refining reaction also uses a hydrogenation refining catalyst; and / or, in step S3, the hydrocracking reaction also uses a hydrocracking catalyst.

[0011] Further, the hydrogenation stabilizing catalyst comprises an alumina support and an oxide of an active metal element supported on the alumina support, wherein the active metal element comprises a Group VIII element and / or a Group VI element; preferably, the weight percentage of the Group VIII element oxide is 0.5-10 wt.%, more preferably 2-6 wt.%; the weight percentage of the Group VI element oxide is 10-30 wt.%, more preferably 15-20 wt.%. wt.%; preferably, the Group VIII element is Ni and the Group VI element is Mo; and / or, the hydrorefining catalyst comprises a support and an oxide of an active metal element supported on the support, the support comprising one or more of amorphous alumina, silica, and aluminum silicate, and the active metal element comprising a Group VIB element and / or a Group VIII element; preferably, the weight percentage of the oxide of the Group VIB element is 0.5~30 wt.%, and the weight percentage of the oxide of the Group VIII element is 1~10 wt.%; preferably, the Group VIB element comprises Mo and / or W, and the Group VIII element comprises Co and / or Ni; and / or The hydrocracking catalyst comprises a support and an oxide of an active metal element supported on the support. The support includes a molecular sieve and alumina. The molecular sieve includes one or more of USY molecular sieve, β-type molecular sieve, and SAPO molecular sieve. The active metal element includes a Group VIB element and / or a Group VIII element. Preferably, the weight percentage of the molecular sieve is 10-40 wt.%, the weight percentage of the oxide of the Group VIB element is 0.5-30 wt.%, and the weight percentage of the oxide of the Group VIII element is 1-5 wt.%. Preferably, the Group VIB element includes Mo and / or W, and the Group VIII metal includes Co and / or Ni.

[0012] Furthermore, the temperature of the hydrogenation stabilization reaction is lower than that of the hydrogenation refining reaction, with a difference of 5~15℃; and / or, the pressure of the hydrogenation stabilization reaction is higher than that of the hydrogenation refining reaction, with a difference of 1~2MPa.

[0013] Further, in step S4, the lubricating additive includes one or more of fatty acid compounds, alcohol ether compounds, amine compounds and ester compounds; and / or, in the coal-based hot air engine fuel, the weight percentage of the lubricating additive is 50~10000ppm, preferably 200~500ppm.

[0014] By applying the technical solution of this invention, through multi-stage hydrogenation process gradient control involving hydrogenation stabilization, hydrogenation refining, and hydrocracking, deep removal of heteroatoms such as sulfur, nitrogen, and oxygen from crude oil produced by direct coal liquefaction can be achieved, along with efficient saturated conversion of high-content aromatics. This significantly reduces carbon buildup in the gas turbine, effectively extends equipment lifespan, and improves the continuity and stability of fuel combustion. It is better suited to the operational requirements of stable combustion and efficient energy release in the gas turbine. Furthermore, due to the high cycloalkane content of coal-based fuels, the low-temperature fluidity of the fuel can be improved, expanding its low-temperature application range. Simultaneously, by fully blending the coal-based gas turbine fuel components with lubricating additives, the lubrication performance of the fuel can be further optimized, preventing wear on the gas turbine fuel delivery and combustion systems, and improving equipment operational reliability. Attached Figure Description

[0015] 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:

[0016] Figure 1 A process flow diagram of the preparation method of coal-based hot air engine fuel according to Embodiment 1 of the present invention is shown.

[0017] The above figures include the following reference numerals:

[0018] 1. Coal direct liquefaction reactor; 2. Third fractionation tower; 3. Hydrogenation stabilization reactor; 4. First fractionation tower; 5. Hydrogenation refining reactor; 6. Hydrogenation cracking reactor; 7. Second fractionation tower.

[0019] A. Hydrogen; B. Coal-oil slurry; C. Crude product of direct coal liquefaction; D. Crude oil from direct coal liquefaction; E. Residue; F. Hydrogenated stabilized oil; G. Stabilized distillate oil; H. Hydrogenated refined oil; I. Hydrocracking oil; J. Fuel components for coal-based gas turbines; K. Lubricating additives; L. Coal-based gas turbine fuel. Detailed Implementation

[0020] 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.

[0021] As described in the background section of this invention, the prior art has the problem that using crude oil from direct coal liquefaction as fuel for hot air engines leads to severe carbon buildup in the hot air engines, reduced operational stability, and affects the service life and combustion efficiency of the equipment. To address the aforementioned problems, in a typical embodiment of the present invention, a method for preparing coal-based thermal engine fuel is provided, comprising the following steps: Step S1, mixing crude coal direct liquefaction oil with hydrogen and performing a hydrogenation stabilization reaction to obtain hydrogenated stabilized oil, and subjecting the hydrogenated stabilized oil to a first fractionation to obtain stabilized distillate oil; Step S2, mixing the stabilized distillate oil with hydrogen and performing a hydrogenation refining reaction to obtain hydrogenated refined oil; Step S3, mixing the hydrogenated refined oil with hydrogen and performing a hydrogenation cracking reaction to obtain hydrogenated cracked oil, and subjecting the hydrogenated cracked oil to a second fractionation to obtain coal-based thermal engine fuel components; Step S4, mixing the coal-based thermal engine fuel components with a lubricating additive to obtain coal-based thermal engine fuel; wherein, the crude coal direct liquefaction oil contains 70-85 wt.% aromatics, 200-400 mg / kg sulfur atoms, and 2000-4000 mg / kg nitrogen atoms.

[0022] Coal direct liquefaction crude oil contains high concentrations of polycyclic aromatic hydrocarbons (PAHs) and heteroatom compounds, resulting in poor oil stability, easy oxidation and coking, and poor low-temperature fluidity. Furthermore, the combustion of PAHs easily produces carbon deposits, severely damaging the combustion chamber and pipelines of the gas turbine, making it unsuitable for the demanding operating conditions of the gas turbine. This invention first performs a hydrogenation stabilization reaction on the coal direct liquefaction crude oil in a hydrogen atmosphere, converting olefins, some reactive aromatics, and sulfur- and nitrogen-containing functional groups in the crude oil into saturated hydrocarbons, hydrogen sulfide, and ammonia, thus reducing the oil's reactivity and coking tendency. Subsequently, the hydrogenated stabilized oil undergoes a first fractionation, separating light volatiles and heavy residues, retaining the middle fraction as the stabilized oil for subsequent hydrogenation.

[0023] The stabilized distillate is then subjected to hydrorefining to further remove residual sulfides and nitrogen oxides. Simultaneously, some polycyclic aromatic hydrocarbons undergo hydrogenation saturation, converting to monocyclic or polycyclic alkanes, significantly reducing the aromatic content of the oil and yielding hydrorefined oil. This hydrorefined oil is then subjected to hydrocracking to further saturate the aromatics and achieve macromolecular cracking and upgrading, breaking down the heavy components into the target fraction to obtain hydrocracking oil. A second fractionation process separates hydrocarbons with saturation and chain lengths suitable for the distillation range of gas turbine fuels, yielding coal-based gas turbine fuel components.

[0024] Finally, the coal-based gas engine fuel components are mixed with lubricating additives, so that the lubricating additives are uniformly dispersed in the coal-based gas engine fuel components. Since the lubricating additive molecules can form a dense and stable adsorption protective film on the metal friction surface, they can isolate the direct hard contact between the metal contact surfaces and weaken the frictional shearing effect. Therefore, the frictional wear generated during the transportation and combustion of fuel in the gas engine can be significantly reduced.

[0025] This invention utilizes a gradient hydrogenation process involving hydrogenation stabilization, hydrogenation refining, and hydrocracking to achieve deep removal of heteroatoms such as sulfur, nitrogen, and oxygen from crude oil produced by direct coal liquefaction. It also enables efficient saturated conversion of high-content aromatics, significantly reducing carbon buildup in the gas turbine, effectively extending equipment lifespan, and improving the continuity and stability of fuel combustion. This makes it more suitable for the stable combustion and efficient energy release requirements of the gas turbine. Due to the significantly reduced polycyclic aromatic hydrocarbon (PAH) content and significantly increased cycloalkanes content in the oil after process optimization, the fuel's low-temperature fluidity is improved, adapting to complex operating scenarios such as underwater and low-temperature environments (approximately -20 to -50°C), thus expanding the fuel's low-temperature application range. Furthermore, by fully blending the coal-based gas turbine fuel components with lubricating additives, the fuel's lubrication performance can be further optimized, preventing wear on the gas turbine fuel delivery and combustion systems, and improving equipment operational reliability.

[0026] In a preferred embodiment, step S1 further includes the following steps: mixing coal with a solvent to obtain an oil-coal slurry; mixing the oil-coal slurry with hydrogen; and sequentially performing a direct coal liquefaction reaction and a third fractionation to obtain crude oil from direct coal liquefaction and residue. During the process of mixing coal with a solvent to form the oil-coal slurry, the solvent can disperse coal particles, reduce system viscosity, and transfer hydrogen. After the oil-coal slurry is mixed with hydrogen, the macromolecular structure of the coal breaks down under pyrolysis and hydrogenation, generating liquid hydrocarbon products and gaseous small molecules, yielding crude direct coal liquefaction product. The crude direct liquefaction product undergoes a third fractionation; the light liquid phase component is extracted as crude oil from direct coal liquefaction, while the unconverted residue is discharged as solid residue, achieving effective separation of oil and solid residue.

[0027] To further improve the quality of crude oil from direct coal liquefaction and make its composition more suitable for the preparation of coal-based gas turbine fuel, in some embodiments, the solvent is a hydrogenated product of direct coal liquefaction oil with a distillation range of 220-450°C; and / or, the solid content of the coal-oil slurry is 45-50%; and / or, the temperature of the direct coal liquefaction reaction is 430-465°C, the pressure is 15-19 MPa, the gas-liquid ratio is 600-1000 NL / kg, and the space velocity of the coal-oil slurry is 0.7-1 t·m. -3 h -1In some embodiments, the method further includes a step of mixing a coal direct liquefaction catalyst with an oil-coal slurry to carry out a coal direct liquefaction reaction, wherein the coal direct liquefaction catalyst is γ-FeOOH with a diameter of 20-30 nm and a length of 100-180 nm; and / or, the coal direct liquefaction catalyst includes iron and sulfur, wherein the weight ratio of iron to coal is (0.5-1):100, and the weight ratio of sulfur to iron is (1.5-2.5):1.

[0028] In a preferred embodiment, in step S1, the crude oil from direct coal liquefaction contains 70-80 wt.% aromatics, 200-300 mg / kg sulfur, and 2000-3000 mg / kg nitrogen. The crude oil with these compositional levels can further promote the depth of subsequent hydrogenation reactions, facilitating efficient saturation of aromatic rings and complete removal of heteroatoms. This significantly enhances the adaptability of the entire process to feedstock characteristics, improving the combustion stability and compositional homogeneity of the final fuel.

[0029] In a preferred embodiment, in step S1, the hydrogenation stabilization reaction is carried out at a reaction temperature of 330-390°C, a reaction pressure of 10-15 MPa, and a volume hourly space velocity of 0.8-2.5 h⁻¹. -1 The hydrogen-to-oil ratio is 600-1000 V / V; and / or, the lower limit of the temperature for the first fractionation is 200-260°C; and / or, the upper limit of the temperature for the first fractionation is 380-480°C; and / or, the weight percentage of aromatics in the stabilized distillate is 50-70 wt.%, the sulfur content is 10-50 mg / kg, and the nitrogen content is 1000-2000 mg / kg.

[0030] The hydrostabilization reaction, carried out within the aforementioned temperature and pressure range, further promotes the targeted hydroremoval of light heteroatom compounds, reduces the tendency for coking in subsequent reactions, and makes the thermal behavior of the oil more stable. The volume hourly space velocity and hydrogen-to-oil ratio within this range further enhance the mass transfer efficiency of hydrogen at the catalyst interface, making it easier to achieve reaction homogeneity and controllability. The first fractionation temperature being within this range is more conducive to retaining light volatile components, concentrating the feedstock entering subsequent processes within the mid-boiling point range, increasing the yield of hydrorefining, and simultaneously helping to retain sufficient amounts of convertible components, further reducing target fraction loss and feedstock depletion.

[0031] Due to the aforementioned hydrogenation stabilization reaction, the aromatic and sulfur / nitrogen content in the stabilized distillate can be maintained at the above-mentioned levels. Furthermore, the synergistic efficiency of the hydrorefining catalyst in aromatic ring saturation and heteroatom removal can be further improved, resulting in a more uniform product composition distribution. This makes it more conducive to achieving highly selective conversion from stabilized distillate to hydrorefined oil and enhancing the adaptability of the process.

[0032] In a preferred embodiment, in step S2, the temperature of the hydrogenation refining reaction is 340~400℃, the reaction pressure is 6.0~19.0MPa, and the volume hourly space velocity is 0.3~2.0h. -1 The hydrogen-to-oil ratio is 500~1500 V / V; preferably, the hydrogenation refining reaction temperature is 360~390℃, the reaction pressure is 12.0~17.0 MPa, and the volume hourly space velocity is 0.5~1.5 h⁻¹. -1 The hydrogen-to-oil ratio is 800~1000V / V.

[0033] The hydrorefining reaction, carried out at the aforementioned temperature and pressure, further promotes the deep synergistic effect of aromatic saturation and heteroatom removal, enabling the more effective conversion of residual sulfur, nitrogen, and polycyclic structures in the oil into saturated hydrocarbons. The aforementioned volume hourly space velocity and hydrogen-to-oil ratio enhance the contact efficiency between the reactants and hydrogen, facilitating more uniform gas-liquid mixing and thus further improving the purity and compositional homogeneity of the products.

[0034] In a preferred embodiment, in step S3, the hydrocracking reaction temperature is 330~400℃, the reaction pressure is 8.0~19.0MPa, the volume hourly space velocity is 1.0~4.0h⁻¹, and the hydrogen-to-oil ratio is 500~1500V / V; preferably, the hydrocracking reaction temperature is 350~380℃; the reaction pressure is 10~15MPa, the volume hourly space velocity is 1.5~2.0h⁻¹, and the hydrogen-to-oil ratio is 800~1000V / V; and / or, the lower limit of the second fractionation temperature is 240~260℃, and the upper limit of the temperature is 300~350℃.

[0035] Hydrocracking reactions carried out at the aforementioned temperatures and pressures can further promote the directional chain scission of large cycloalkanes and aromatics, resulting in a more concentrated product distribution within the target distillation range. The aforementioned volume hourly space velocity and hydrogen-to-oil ratio further enhance the mass transfer efficiency between the solid and liquid phases, thereby further improving the efficiency of hydrocracking and facilitating the balance between cracking and saturation. With the lower and upper limits of the second fractionation temperature falling within the aforementioned range, the resulting middle fraction is more likely to meet the requirements of hot gas engines and is more likely to reduce the volatilization of light components or the mixing of heavy components, thus further improving the structural consistency and combustion compatibility of the fuel composition.

[0036] To further improve the selectivity and efficiency of the hydrogenation reaction, in a preferred embodiment, in step S1, the hydrogenation stabilization reaction also uses a hydrogenation stabilization catalyst; and / or, in step S2, the hydrogenation refining reaction also uses a hydrogenation refining catalyst; and / or, in step S3, the hydrocracking reaction also uses a hydrocracking catalyst.

[0037] In a preferred embodiment, the hydrogenation stabilizing catalyst comprises an alumina support and an oxide of an active metal element supported on the alumina support, wherein the active metal element comprises a Group VIII element and / or a Group VI element; preferably, the weight percentage of the Group VIII element oxide is 0.5-10 wt.%, more preferably 2-6 wt.%; and the weight percentage of the Group VI element oxide is 10-30 wt.%, more preferably 15-20 wt.%. wt.%; preferably, the Group VIII element is Ni and the Group VI element is Mo; and / or, the hydrorefining catalyst comprises a support and an oxide of an active metal element supported on the support, the support comprising one or more of amorphous alumina, silica, and aluminum silicate, and the active metal element comprising a Group VIB element and / or a Group VIII element; preferably, the weight percentage of the oxide of the Group VIB element is 0.5~30 wt.%, and the weight percentage of the oxide of the Group VIII element is 1~10 wt.%; preferably, the Group VIB element comprises Mo and / or W, and the Group VIII element comprises Co and / or Ni; and / or The hydrocracking catalyst comprises a support and an oxide of an active metal element supported on the support. The support includes a molecular sieve and alumina. The molecular sieve includes one or more of USY molecular sieve, β-type molecular sieve, and SAPO molecular sieve. The active metal element includes a Group VIB element and / or a Group VIII element. Preferably, the weight percentage of the molecular sieve is 10-40 wt.%, the weight percentage of the oxide of the Group VIB element is 0.5-30 wt.%, and the weight percentage of the oxide of the Group VIII element is 1-5 wt.%. Preferably, the Group VIB element includes Mo and / or W, and the Group VIII metal includes Co and / or Ni.

[0038] The catalysts for the three-step hydrogenation process utilize the aforementioned different types of active metal elements, which can further promote the orderly progress of stepwise hydrogenation, further promote the orderly removal of aromatics and heteroatoms from the feedstock, and better reduce problems such as reduced impurity removal efficiency caused by disordered removal sequence.

[0039] Specifically, hydrostabilizing catalysts primarily focus on removing unstable components prone to coking and protecting subsequent catalysts. Using the aforementioned components facilitates the rapid hydrogenation saturation of olefins and large-molecule active aromatics in crude oil, and removes some easily convertible sulfides and nitrides. This further reduces the reactivity and coking tendency of the oil, and minimizes the risk of heavy impurities entering the subsequent reaction system and causing catalyst poisoning or blockage.

[0040] Hydrorefining catalysts primarily focus on the deep removal of sulfur, nitrogen heteroatoms, and further saturation of polycyclic aromatic hydrocarbons. Using these components facilitates the removal of residual deep sulfides and nitrogen oxides from stable distillate oils, reducing nitrogen content to a lower level to ensure that subsequent hydrocracking catalysts are not poisoned by nitrogen, while further reducing aromatic hydrocarbon content.

[0041] Hydrocracking catalysts primarily focus on deep saturation of aromatics and the upgrading of macromolecular cracking. Using the aforementioned components, the shape-selective catalytic performance of molecular sieves and their strong acidic centers are utilized to achieve efficient saturation conversion of remaining aromatics. Furthermore, macromolecular alkanes and cycloalkanes are directionally chain-severed and cracked into lighter components within the target distillation range, thereby further improving the final fuel's distillation range distribution, density, and cryogenic fluidity to meet the stringent operating requirements of hot gas engines.

[0042] To further improve the efficiency and selectivity of the stepwise hydrogenation reaction, and to make the properties of the obtained coal-based gas engine fuel components more suitable for the preparation of coal-based gas engine fuels, in a preferred embodiment, the temperature of the hydrogenation stabilization reaction is lower than the temperature of the hydrogenation refining reaction, with a difference of 5-15°C; and / or, the pressure of the hydrogenation stabilization reaction is higher than the pressure of the hydrogenation refining reaction, with a difference of 1-2 MPa; and / or, the volume hourly space velocity (VHSV) of the hydrogenation stabilization reaction is higher than that of the hydrogenation refining reaction, with a difference of 0.4-0.8 h⁻¹. -1 ; and / or, the volume hourly space velocity (VHSV) of the hydrorefining reaction is less than that of the hydrocracking reaction, with a difference of 0.8–1.1 h⁻¹. -1 .

[0043] The temperature, pressure, and space velocity limits for the three-step hydrogenation reaction vary to varying degrees. Hydrogenation stabilizes a portion of the aromatic hydrocarbon content and removes some heteroatoms; hydrorefining saturates most of the aromatic hydrocarbons and reduces nitrogen atom concentration to below 5 ppm, thus better ensuring that the subsequent hydrocracking catalyst is not poisoned; hydrocracking further saturates the aromatic hydrocarbons and achieves macromolecular cracking and upgrading, breaking down heavy components into the target fraction. Limiting the temperature, pressure, and space velocity of the three-step hydrogenation reaction according to the above-mentioned relationships further promotes the orderly progress of stepwise hydrogenation, further promotes the orderly removal of aromatic hydrocarbons and heteroatoms from the feedstock, and is more conducive to reducing problems such as reduced impurity removal efficiency caused by disordered removal sequences.

[0044] In a preferred embodiment, the lubricating additive includes one or more of fatty acid compounds, alcohol ether compounds, amine compounds and ester compounds; and / or, in the coal-based hot air engine fuel, the weight percentage of the lubricating additive is 50 to 10,000 ppm, preferably 200 to 500 ppm.

[0045] The lubricating additives selected are of the above types, including fatty acid compounds such as oleic acid, stearic acid, and palmitic acid; alcohol ether compounds such as ethylene glycol monomethyl ether and propylene glycol polyether; amine compounds such as fatty acid amides and erucic acid amides; and ester compounds such as methyl oleate and glyceryl stearate. These compounds can further promote the formation of an oil film on the metal surface during high-pressure fuel transportation and injection, improve the anti-wear performance of components, and make the system operate more smoothly. When the amount of lubricating additive added is within the above range, it can further improve the continuity and uniformity of the lubrication effect, and is more conducive to reducing insufficient protection due to too low an addition or increased carbon deposit tendency due to too high an addition. This allows the fuel to maintain high energy density while achieving a better balance with lubrication performance. To make the acidity, low corrosiveness, and environmental friendliness of the lubricating additives more suitable for the needs of coal-based gas turbine fuels, fatty acid ester anti-wear agents are preferred.

[0046] To further optimize the lubrication performance of fuel, and to reduce wear on the fuel delivery and combustion systems of hot air engines, thereby improving the reliability of equipment operation, in a preferred embodiment, in step S4, the lubricating additive includes one or more of methyl oleate, methyl palmitate, and methyl stearate.

[0047] In some embodiments, the process flow diagram of the method for preparing coal-based gas turbine fuel is as follows: Figure 1 As shown, hydrogen A and coal-oil slurry B are fed into the direct coal liquefaction reactor 1 for direct coal liquefaction reaction to obtain crude direct coal liquefaction product C, which is then fed into the third fractionation tower 2 for solid-liquid separation to obtain crude direct coal liquefaction oil D and residue E. Crude direct coal liquefaction oil D is fed into the hydrostabilization reactor 3 to obtain hydrostabilized oil F; it is fed into the first fractionation tower 4 to obtain stabilized distillate oil G; it is fed into the hydrorefining reactor 5 to obtain hydrorefined oil H; it is fed into the hydrocracking reactor 6 to obtain hydrocracking oil I; it is fed into the second fractionation tower 7 to obtain coal-based thermal engine fuel component J; lubricating additive K is mixed with coal-based thermal engine fuel component J to obtain coal-based thermal engine fuel L.

[0048] 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.

[0049] Example 1

[0050] The process flow diagram for Example 1 is shown below. Figure 1 ;

[0051] Step S1: Coal is mixed with a solvent to obtain an oil-coal slurry (solid content 45%). The oil-coal slurry is then mixed with hydrogen and fed into the direct coal liquefaction reaction unit 1 for direct coal liquefaction reaction (temperature 450℃, pressure 17MPa, gas-liquid ratio 800NL / kg, oil-coal slurry space velocity 0.8t·m). -3 h -1The catalyst is γ-FeOOH (the weight ratio of catalyst to coal is 2:1), and crude product of direct coal liquefaction is obtained. The crude product is then subjected to solid-liquid separation in fractionation tower 2 to obtain crude oil of direct coal liquefaction and residue. The crude oil of direct coal liquefaction contains 75 wt.% aromatics, 250 mg / kg sulfur, and 2517 mg / kg nitrogen.

[0052] Hydrogenation stabilization catalyst (the content and type of active metal oxides in the catalyst vary, see Tables 3 and 4 for details) is loaded into hydrogenation stabilization reactor 3. Coal direct liquefaction crude oil and hydrogen are introduced into hydrogenation stabilization reactor 3 to carry out hydrogenation stabilization reaction, and hydrogenated stabilized oil is obtained. The hydrogenated stabilized oil is then fed into fractionation tower 4 for first fractionation to obtain stabilized distillate oil. The conditions for hydrogenation stabilization reaction and first fractionation are shown in Table 1. The composition levels of the stabilized distillate oil are shown in Table 5.

[0053] Step S2: Hydrorefining catalyst (the content and type of active metal oxides in the catalyst vary, see Tables 3 and 4 for details, with MoO3 accounting for 3.6 wt.% and WO3 accounting for 30 wt.%) is loaded into hydrorefining reactor 5. Stable distillate oil and hydrogen are introduced into hydrorefining reactor 5 to carry out the hydrorefining reaction and obtain hydrorefined oil; the conditions for the hydrorefining reaction are shown in Table 2.

[0054] Step S3: Hydrocracking catalyst (the content and type of active metal oxides in the catalyst vary, see Tables 3 and 4 for details) is loaded into hydrocracking reactor 6. Hydrorefined oil and hydrogen are introduced into hydrocracking reactor 6 to carry out hydrocracking reaction to obtain hydrocracking oil. The hydrocracking oil enters fractionation tower 7 to obtain coal-based gas turbine fuel components. The hydrocracking reaction is shown in Table 2, and the conditions for the second fractionation are shown in Table 1.

[0055] Step S4: Add a lubricating additive (methyl oleate) to the coal-based hot air engine fuel component to obtain the coal-based hot air engine fuel, wherein the weight percentage of the lubricating additive is 250 ppm.

[0056] Examples 2 to 10

[0057] The difference from Example 1 is that the conditions for the hydrorefining reaction, the first fractionation, the hydrocracking reaction, and the second fractionation, as well as the amount of lubricating additive added, are different, as detailed in Tables 1 and 2.

[0058] Example 11

[0059] The difference from Example 1 is that,

[0060] In step S1, the conditions for the hydrogenation stabilization reaction are different, as detailed in Table 1;

[0061] In step S4, oleic acid is used as the lubricating additive.

[0062] Example 12

[0063] The difference from Example 1 is that,

[0064] In step S1, the conditions for the hydrogenation stabilization reaction are different, as detailed in Table 1;

[0065] In step S4, the lubricating additive is ethylene glycol monomethyl ether.

[0066] Example 13

[0067] The difference from Example 1 is that,

[0068] In step S1, the aromatic hydrocarbon content in the crude oil from direct coal liquefaction is 70 wt.%, the sulfur atom content is 200 mg / kg, and the nitrogen atom content is 2000 mg / kg; the content and types of active metal oxides in the hydrogenation stabilization catalyst are different, as shown in Tables 3 and 4.

[0069] In step S2, the content and type of active metal oxides in the hydrorefining catalyst vary, as detailed in Tables 3 and 4.

[0070] In step S3, the content and types of active metal oxides in the hydrocracking catalyst vary, as detailed in Tables 3 and 4.

[0071] Example 14

[0072] The difference from Example 1 is that,

[0073] In step S1, the aromatic hydrocarbon content in the crude oil from direct coal liquefaction is 80 wt.%, the sulfur content is 300 mg / kg, and the nitrogen content is 3000 mg / kg. The content and types of active metal oxides in the hydrogenation stabilization catalyst are different, as shown in Tables 3 and 4.

[0074] In step S2, the content and type of active metal oxides in the hydrorefining catalyst vary, as detailed in Tables 3 and 4.

[0075] In step S3, the content and types of active metal oxides in the hydrocracking catalyst vary, as detailed in Tables 3 and 4.

[0076] Example 15

[0077] The difference from Example 1 is that,

[0078] In step S1, the content of active metal oxides in the hydrogenation stabilization catalyst varies, as shown in Table 3.

[0079] In step S2, the content of active metal oxides in the hydrorefining catalyst varies, as shown in Table 3.

[0080] In step S3, the content of active metal oxides in the hydrocracking catalyst varies, as shown in Table 3.

[0081] Example 16

[0082] The difference from Example 1 is that,

[0083] In step S1, the content of active metal oxides in the hydrogenation stabilization catalyst varies, as shown in Table 3.

[0084] In step S2, the content of active metal oxides in the hydrorefining catalyst varies, as shown in Table 3.

[0085] In step S3, the content of active metal oxides in the hydrocracking catalyst varies, as shown in Table 3.

[0086] Comparative Example 1

[0087] The existing petroleum-based hot air engine fuel is petroleum-based and conforms to the hot air engine fuel specification GJB 7217-2011.

[0088] Comparative Example 2

[0089] The existing direct coal liquefaction diesel is produced by the Ordos branch of China Shenhua Coal-to-Oil Chemical Co., Ltd., and meets the standards for vehicle diesel.

[0090] Comparative Example 3

[0091] The difference from Example 1 is that steps S2 and S3 are not performed;

[0092] In step S4, the stabilized distillate oil is mixed with a lubricating additive to obtain coal-based gas turbine fuel.

[0093] Comparative Example 4

[0094] The difference from Example 1 is that step S4 is omitted;

[0095] In step S3, the obtained coal-based gas engine fuel component is coal-based gas engine fuel.

[0096] Performance testing:

[0097] The coal-based gas turbine fuels prepared in the above embodiments and comparative examples were analyzed and tested as follows, and the results are shown in Tables 5 to 6.

[0098] (1) Density testing was conducted in accordance with GB / T 1884-2000 and GB / T 1885-1998. Specifically, GB / T 1884-2000 was used to measure the density of coal-based hot air engine fuel, and GB / T 1885-1998 was used to convert the measured values ​​to the density at 20℃.

[0099] (2) The sulfur content was tested according to SH / T 0689-2000.

[0100] (3) The nitrogen content was tested according to NB / SH / T 0704-2010.

[0101] (3) Kinematic viscosity test shall be conducted in accordance with GB / T 265-1988.

[0102] (4) Flash point is tested according to GB / T 261-2021.

[0103] (5) The distillation range was tested according to GB / T 6536-2010.

[0104] (6) Pour point: Tested according to GB / T 510-2018. Cold filter plugging point: Tested according to SH / T 0248-2019.

[0105] The low-temperature fluidity of oil products is evaluated by their pour point and cold filter plugging point. The lower the pour point and cold filter plugging point, the better the low-temperature fluidity.

[0106] (7) Lubricity: Tested according to NB / SH / T 0765-2021.

[0107] (8) Thermal stability: Tested according to GB / T 9169-2023.

[0108] Table 1

[0109]

[0110] In Table 1, " / " indicates "same as Example 1".

[0111] Table 2

[0112]

[0113] Table 3

[0114]

[0115] In Table 3, " / " indicates "same as Example 1".

[0116] Table 4

[0117]

[0118] Table 5

[0119]

[0120] Table 6

[0121]

[0122] As can be seen, Comparative Example 1 is a petroleum-based fuel with a low density and a relatively high sulfur content. Comparative Example 2 is a diesel fraction with a low boiling range, which also fails to meet the requirements, resulting in an unacceptable flash point. Comparative Example 3, due to the lack of hydrorefining and hydromodification, fails to meet the requirements for sulfur and nitrogen content, pour point, cold filter plugging point, viscosity, boiling range, and thermal stability. Comparative Example 4, due to the absence of anti-wear agents, fails to meet the lubricity requirements.

[0123] As can be seen from the above, the coal liquefaction hydrotreated stabilized oil prepared in the various embodiments of the present invention, through deep quality improvement processes such as hydrotreatment stabilization, hydrorefining, and hydrocracking, and optimized formulation with anti-wear agents, can effectively reduce sulfur and nitrogen content, precisely control core physicochemical indicators such as density, viscosity, distillation range, and flash point, while ensuring excellent lubrication performance. All parameters meet standard requirements, resulting in excellent overall performance and wider applicability. Excellent lubrication performance can significantly reduce wear in gas turbine fuel delivery and combustion systems, improve equipment operational reliability, and thus significantly extend equipment service life.

[0124] Furthermore, it can be seen that the overall effect is better when all process parameters are within the preferred range of the present invention.

[0125] 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 thermal engine fuel, characterized in that, Includes the following steps: Step S1: Mix crude oil from direct coal liquefaction with hydrogen and carry out a hydrogenation stabilization reaction to obtain hydrogenated stabilized oil. Then, perform a first fractionation on the hydrogenated stabilized oil to obtain stabilized distillate oil. Step S2: The stabilized distillate oil is mixed with hydrogen and subjected to a hydrorefining reaction to obtain hydrorefined oil. Step S3: Mix the hydrotreated oil with hydrogen and carry out hydrocracking reaction to obtain hydrocracking oil. Then, perform a second fractionation on the hydrocracking oil to obtain coal-based gas turbine fuel components. Step S4: Mix the coal-based gas engine fuel components with a lubricating additive to obtain the coal-based gas engine fuel; The crude oil from direct coal liquefaction contains 70-85 wt.% aromatics, 200-400 mg / kg sulfur, and 2000-4000 mg / kg nitrogen.

2. The method for preparing coal-based thermal engine fuel according to claim 1, characterized in that, Step S1 further includes the following steps: mixing coal with a solvent to obtain an oil-coal slurry; mixing the oil-coal slurry with hydrogen; and sequentially performing a direct coal liquefaction reaction and a third fractionation to obtain the direct coal liquefaction crude oil and residue; and / or, The crude oil from direct coal liquefaction has an aromatic hydrocarbon content of 70-80 wt.%, a sulfur content of 200-300 mg / kg, and a nitrogen content of 2000-3000 mg / kg.

3. The method for preparing coal-based thermal gas engine fuel according to claim 1 or 2, characterized in that, In step S1 The hydrogenation stabilization reaction is carried out at a temperature of 330–390 °C, a pressure of 10–15 MPa, and a volume hourly space velocity of 0.8–2.5 h⁻¹. -1 The hydrogen-to-oil ratio is 600~1000V / V; and / or, The lower limit of the temperature of the first fractionation is 200~260℃, preferably 220~250℃; and / or, The upper limit of the temperature for the first fractionation is 380~480℃, preferably 400~450℃; and / or, The stabilized distillate oil contains 50-70 wt.% aromatics, 10-50 mg / kg sulfur, and 1000-2000 mg / kg nitrogen.

4. The method for preparing coal-based thermal engine fuel according to any one of claims 1 to 3, characterized in that, In step S2 The hydrogenation refining reaction is carried out at a temperature of 340–400 °C, a reaction pressure of 6.0–19.0 ​​MPa, and a volume hourly space velocity of 0.3–2.0 h⁻¹. -1 The hydrogen-to-oil ratio is 500~1500V / V. Preferably, the hydrorefining reaction is carried out at a temperature of 360-390°C, a reaction pressure of 12.0-17.0 MPa, and a volume hourly space velocity of 0.5-1.5 h⁻¹. -1 The hydrogen-to-oil ratio is 800~1000V / V.

5. The method for preparing coal-based thermal engine fuel according to any one of claims 1 to 4, characterized in that, In step S3 The hydrocracking reaction is carried out at a temperature of 330–400 °C, a reaction pressure of 8.0–19.0 ​​MPa, and a volume hourly space velocity of 1.0–4.0 h⁻¹. -1 The hydrogen-to-oil ratio is 500~1500V / V; Preferably, the hydrocracking reaction is carried out at a temperature of 350-380°C, a reaction pressure of 10-15 MPa, and a volume hourly space velocity of 1.5-2.0 h⁻¹. -1 The hydrogen-to-oil ratio is 800~1000V / V; and / or, The lower limit of the second fractionation temperature is 240~260℃, and the upper limit of the temperature is 300~350℃.

6. The method for preparing coal-based thermal engine fuel according to any one of claims 1 to 5, characterized in that, In step S1, the hydrogenation stabilization reaction further utilizes a hydrogenation stabilization catalyst; and / or, In step S2, the hydrorefining reaction further utilizes a hydrorefining catalyst; and / or, In step S3, the hydrocracking reaction also uses a hydrocracking catalyst.

7. The method for preparing coal-based thermal gas engine fuel according to claim 6, characterized in that, The hydrogenation stabilizing catalyst comprises an alumina support and an oxide of an active metal element supported on the alumina support, wherein the active metal element comprises a Group VIII element and / or a Group VI element; preferably, the weight percentage of the Group VIII element oxide is 0.5-10 wt.%, more preferably 2-6 wt.%; the weight percentage of the Group VI element oxide is 10-30 wt.%, more preferably 15-20 wt.%; preferably, the Group VIII element is Ni and the Group VI element is Mo; and / or, The hydrorefining catalyst comprises a support and an oxide of an active metal element supported on the support. The support comprises one or more of amorphous alumina, silica, and aluminum silicate. The active metal element comprises a Group VIB element and / or a Group VIII element. Preferably, the weight percentage of the Group VIB element oxide is 0.5-30 wt.%, and the weight percentage of the Group VIII element oxide is 1-10 wt.%. Preferably, the Group VIB element comprises Mo and / or W, and the Group VIII element comprises Co and / or Ni. And / or... The hydrocracking catalyst comprises a support and an oxide of an active metal element supported on the support. The support comprises a molecular sieve and alumina. The molecular sieve comprises one or more of USY molecular sieve, β-type molecular sieve, and SAPO molecular sieve. The active metal element comprises a Group VIB element and / or a Group VIII element. Preferably, the molecular sieve has a weight percentage of 10-40 wt.%, the oxide of the Group VIB element has a weight percentage of 0.5-30 wt.%, and the oxide of the Group VIII element has a weight percentage of 1-5 wt.%. Preferably, the Group VIB element comprises Mo and / or W, and the Group VIII metal comprises Co and / or Ni.

8. The method for preparing coal-based thermal engine fuel according to any one of claims 1 to 7, characterized in that, The temperature of the hydrogenation stabilization reaction is lower than the temperature of the hydrogenation refining reaction, with a difference of 5~15℃; and / or, The pressure of the hydrogenation stabilization reaction is greater than the pressure of the hydrogenation refining reaction, with a difference of 1~2 MPa.

9. The method for preparing coal-based thermal engine fuel according to any one of claims 1 to 8, characterized in that, The volume hourly space velocity (VHSV) of the hydrogenation stabilization reaction is greater than that of the hydrogenation purification reaction, with a difference of 0.4–0.8 h⁻¹. -1 ; and / or, The volume hourly space velocity (VHSV) of the hydrorefining reaction is lower than that of the hydrocracking reaction, with a difference of 0.8–1.1 h⁻¹. -1 .

10. The method for preparing coal-based thermal engine fuel according to any one of claims 1 to 9, characterized in that, In step S4 The lubricating additive includes one or more of fatty acid compounds, alcohol ether compounds, amine compounds, and ester compounds; and / or, In the coal-based gas turbine fuel, the weight percentage of the lubricating additive is 50~10000ppm, preferably 200~500ppm.

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