Preparation method of coal-based rocket kerosene

Abstract

The invention relates to the field of coal chemical industry, and discloses a preparation method of coal-based rocket kerosene, which comprises the following steps: mixing a coal indirect liquefaction Fischer-Tropsch synthesis fraction and a coal direct liquefaction fraction, carrying out a deep hydrofining reaction, fractionating, and taking fractions with an initial boiling point of 185-205 DEG C and a final boiling point of 245-265 DEG C to obtain the coal-based rocket kerosene, wherein the mass ratio of the indirect coal liquefaction Fischer-Tropsch synthesis fraction to the direct coal liquefaction fraction is (20 to 40): (80 to 60); the initial boiling point of the indirect coal liquefaction Fischer-Tropsch synthesis fraction is 150-170 DEG C, the final boiling point of the indirect coal liquefaction Fischer-Tropsch synthesis fraction is 290-310 DEG C, the initial boiling point of the direct coal liquefaction fraction is 160-180 DEG C, and the final boiling point of the direct coal liquefaction fraction is 300-320 DEG C.

Description

Technical Field

[0001] This invention relates to the field of coal chemical industry, and specifically to a method for preparing coal-based rocket kerosene. Background Technology

[0002] With the continuous development of aerospace technology and the successive deployment of new-generation launch vehicles, the development of environmentally friendly, non-toxic, and pollution-free liquid propellants has become a trend in liquid propellant development. Among these, rocket kerosene has gained widespread application due to its numerous advantages, including high density, room-temperature storage, wide availability, low toxicity, and safety. Furthermore, considering engine development, reliability testing, random sampling tests, and the development and testing of heavy-lift launch vehicle engines, the demand for aerospace kerosene will further expand to 20,000 tons per year, and this figure is showing a year-on-year increasing trend.

[0003] With dwindling oil resources and a high risk of depletion, the development of new aerospace liquid fuels is imperative to ensure a sustainable and diversified supply. In recent years, as coal chemical production technology has matured and stabilized, the development of alternative energy technologies based primarily on coal-based liquid fuels has gained increasing attention. Coal-based liquid fuels are mainly divided into three categories: direct coal liquefaction oil, indirect coal liquefaction oil, and coal tar fuel oil. Among these, coal tar fuel has been frequently reported for use in the production of aerospace kerosene. Its aromatic hydrocarbon content, exceeding 95%, determines the conditions for conversion into rocket kerosene. However, the high aromatic hydrocarbon content also indicates that coal tar fuel has disadvantages such as low hydrogen content and low calorific value.

[0004] Patent application CN104789260A discloses a method for producing rocket kerosene from coal tar. The method involves separating a fraction with a boiling point of 190-300℃ from the coal tar, and then hydrorefining this fraction in a fixed-bed reactor to obtain a hydrorefined product. The hydrorefined product is then fractionated, and a fraction with a boiling point of 190-280℃ is collected to obtain the rocket kerosene product. Patent application CN103305266A discloses a method for preparing coal-based military fuel and the resulting military fuel. The method involves distilling a feedstock oil (at least one of direct coal liquefaction oil, kerosene co-refining oil, or pretreated coal tar) into at least a light fraction and a heavy fraction. The light fraction is fed into a hydrorefining reactor for further hydrorefining. The hydrorefined oil is then cooled, separated into gas and liquid phases, and then fractionated in a fractionating tower to obtain the military fuel. However, coal tar has a very high aromatic content (over 95%), but it also has the disadvantages of low hydrogen content and low calorific value. Using coal tar to hydrogenate and increase its hydrogen content and calorific value to produce rocket kerosene is relatively expensive.

[0005] Therefore, how to prepare aerospace kerosene using coal-based liquid fuels is currently a bottleneck, and it is crucial for expanding the raw materials and methods for preparing aerospace kerosene and solving the energy crisis. Summary of the Invention

[0006] The purpose of this invention is to overcome the problems of low hydrogen content and low calorific value in existing rocket kerosene products prepared from coal tar fuel, and to provide a method for preparing coal-based rocket kerosene. This method blends direct coal liquefaction fractions and indirect coal liquefaction Fischer-Tropsch synthesis fractions. The preparation method is simple, has a short process flow, low preparation cost, and is suitable for industrial production.

[0007] To achieve the above objectives, the present invention provides a method for preparing coal-based rocket kerosene, the method comprising: mixing coal indirect liquefaction Fischer-Tropsch synthesis fraction and coal direct liquefaction fraction and subjecting them to deep hydrogenation refining reaction, and then fractionating the mixture to obtain the coal-based rocket kerosene by taking the fraction with an initial boiling point of 185~205℃ and a final boiling point of 245~265℃. The mass ratio of the coal indirect liquefaction Fischer-Tropsch synthesis fraction to the coal direct liquefaction fraction is (20~40):(80~60); the initial boiling point of the coal indirect liquefaction Fischer-Tropsch synthesis fraction is 150~170℃, and the final boiling point is 290~310℃; the initial boiling point of the coal direct liquefaction fraction is 160~180℃, and the final boiling point is 300~320℃.

[0008] Preferably, the mass ratio of the coal indirect liquefaction Fischer-Tropsch synthesis fraction to the coal direct liquefaction fraction is (25~35):(75~65).

[0009] Preferably, the operating conditions for the deep hydrogenation refining reaction include: a reaction temperature of 300~365℃, a reaction pressure of 7~13MPa, and a volume hourly space velocity of 1~2.5h. -1 The hydrogen-to-oil ratio is 400-800.

[0010] Preferably, the catalyst for the deep hydrorefining reaction comprises a support and an active component supported on the support, wherein the support is at least one of silicon oxide, aluminum oxide and titanium oxide, and the active component is at least one of cobalt, platinum, palladium, nickel, tungsten and molybdenum.

[0011] Preferably, the method for preparing the Fischer-Tropsch synthesis fraction from coal indirect liquefaction includes: 1) The Fischer-Tropsch synthesis oil from indirect coal liquefaction is subjected to a first fractionation process to obtain the fraction with an initial boiling point of 35-45℃ and a final boiling point of 160-170℃. This fraction is then subjected to a first hydrorefining reaction to obtain hydrorefined tail oil. 2) The hydrorefined tail oil is subjected to a first hydrocracking reaction and then a second fractionation to obtain the coal indirect liquefaction Fischer-Tropsch synthesis fraction.

[0012] Preferably, the first hydrorefining reaction is carried out in a first hydrorefining reactor, the operating conditions of which include: an inlet temperature of 270~320℃, an outlet temperature of 360~400℃, a reaction pressure of 6~10MPa, and a volume hourly space velocity of 2~4h. -1 The hydrogen-to-oil ratio is 300-700.

[0013] Preferably, the first fractionation is carried out in a first fractionation column, and the operating conditions of the first fractionation column include: a bottom temperature of 240~290℃, a bottom pressure of 0.5~1.8MPa, and a top temperature of 120~150℃.

[0014] Preferably, the first hydrocracking reaction is carried out in a first hydrocracking reactor, the operating conditions of which include: inlet temperature of 280~330℃, outlet temperature of 380~450℃, reaction pressure of 7~13MPa, and volume hourly space velocity of 1~4h. -1 The hydrogen-to-oil ratio is 300-700.

[0015] Preferably, the second fractionation is carried out in a second fractionation column, and the operating conditions of the second fractionation column include: a bottom temperature of 260~300℃, a bottom pressure of 0.9~2.1MPa, and a top temperature of 140~170℃.

[0016] Preferably, the content of C5-C100 alkanes in the coal indirect liquefaction Fischer-Tropsch synthesis oil is 80-99.9 vol%; more preferably, the content of n-alkanes in the C5-C100 alkanes is greater than or equal to 90 vol%.

[0017] Preferably, the method for preparing the direct coal liquefaction fraction includes: 1) After the direct coal liquefaction oil undergoes a hydrogenation stabilization reaction, a hydrogenated stabilized fraction is obtained through a third fractionation. The initial boiling point of the hydrogenated stabilized fraction is 40~80℃, and the final boiling point is 340~400℃. 2) The hydrogenated stable fraction is subjected to a second hydrogenation refining reaction and a second hydrogenation cracking reaction in sequence, and then the direct coal liquefaction fraction is obtained by a fourth fractionation.

[0018] Preferably, the operating conditions for the hydrogenation stabilization reaction include: a temperature of 340~400℃ and a pressure of 3~9MPa.

[0019] Preferably, the second hydrorefining reaction is carried out in a second hydrorefining reactor, the operating conditions of which include: inlet temperature of 300-350°C, outlet temperature of 400-450°C, reaction pressure of 2-9 MPa, and volume hourly space velocity of 0.5-3 h⁻¹. -1 The hydrogen-to-oil ratio is 200-700.

[0020] Preferably, the second hydrocracking reaction is carried out in a second hydrocracking reactor, the operating conditions of which include: an inlet temperature of 280~310℃, an outlet temperature of 400~450℃, a reaction pressure of 2~7MPa, and a volume hourly space velocity of 0.5~4h. -1 The hydrogen-to-oil ratio is 200-700.

[0021] Preferably, the third fractionation is carried out in a third fractionation column, and the operating conditions of the third fractionation column include: a bottom temperature of 370~420℃, a top temperature of 140~190℃, and a bottom pressure of 0.7~2.2MPa.

[0022] Preferably, the fourth fractionation is carried out in a fourth fractionation column, and the operating conditions of the fourth fractionation column include: a bottom temperature of 360~400℃, a top temperature of 140~180℃, and a bottom pressure of 0.5~2MPa.

[0023] Compared with the prior art, the present invention has the following advantages: 1) This invention utilizes the Fischer-Tropsch synthesis fraction from indirect coal liquefaction and the direct coal liquefaction fraction for blending and hydrogenation optimization to obtain coal-based rocket kerosene that meets the requirements of current aerospace rocket fuel. This not only overcomes the shortcomings of existing coal tar rocket fuel, which has a high aromatic content but low hydrogen content and low calorific value, but also solves the problems of high density, low viscosity and low calorific value of existing coal-based rocket fuel, thus expanding the range of raw materials and methods for preparing rocket kerosene.

[0024] 2) The coal-based rocket kerosene provided by this invention is similar to the petroleum-based aerospace kerosene currently in service, and has a wide range of sources, abundant resources, simple preparation methods, short process flow, low preparation cost, and is suitable for large-scale industrial production.

[0025] 3) The coal-based rocket fuel prepared by the preparation method of the present invention has the characteristics of high specific impulse, high density, excellent cooling performance, stability and safety, and can be directly applied to the liquid oxygen kerosene engine of the new generation of launch vehicles. Attached Figure Description

[0026] Figure 1 This is a process flow diagram of the preparation of coal-based rocket kerosene in Embodiment 1 of the present invention.

[0027] Explanation of reference numerals in the attached figures 1. Coal indirect liquefaction Fischer-Tropsch synthesis reactor; 2. First fractionation tower; 3. First hydrorefining reactor; 4. First hydrocracking reactor; 5. Second fractionation tower; 6. Coal direct liquefaction reactor; 7. Hydrogenation stabilization reactor; 8. Third fractionation tower; 9. Second hydrorefining reactor; 10. Second hydrocracking reactor; 11. Fourth fractionation tower; 12. Mixing tank; 13. Mixed oil hydrorefining reactor; 14. Rocket kerosene fractionation tower; 15. Rocket kerosene. Detailed Implementation

[0028] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0029] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0030] In the description of this application, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating relative importance or implying the number of technical features indicated. Therefore, unless otherwise stated, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature; "multiple" means two or more. The term "comprising" and any variations thereof mean non-exclusive inclusion, where one or more other features, integers, steps, operations, units, components, and / or combinations thereof may be present or added.

[0031] The preparation method of coal-based rocket kerosene of the present invention includes: mixing coal indirect liquefaction Fischer-Tropsch synthesis fraction and coal direct liquefaction fraction and then subjecting them to deep hydrogenation refining reaction, followed by fractionation to obtain the coal-based rocket kerosene with an initial boiling point of 185~205℃ and a final boiling point of 245~265℃. The mass ratio of the coal indirect liquefaction Fischer-Tropsch synthesis fraction to the coal direct liquefaction fraction is (20~40):(80~60); the initial boiling point of the coal indirect liquefaction Fischer-Tropsch synthesis fraction is 150~170℃, and the final boiling point is 290~310℃; the initial boiling point of the coal direct liquefaction fraction is 160~180℃, and the final boiling point is 300~320℃.

[0032] In this invention, Fischer-Tropsch synthesis fractions from indirect coal liquefaction and direct coal liquefaction fractions are used as raw materials. These are mixed in a mass ratio of (20-40):(80-60) and then subjected to a deep hydrorefining reaction to obtain the product of the deep hydrorefining reaction. The product of the deep hydrorefining reaction is further fractionated, and the fraction with an initial boiling point of 185-205℃ and a final boiling point of 245-265℃ is taken as coal-based rocket kerosene. Within the above boiling range, the fraction has a moderate boiling range, high density, high kinematic viscosity, and high flash point. Further optimization of the boiling range to an initial boiling point of 190-200℃ and a final boiling point of 250-260℃ can further improve the boiling range, density, kinematic viscosity, and flash point of the fraction.

[0033] In this invention, the fractionation of the product from the deep hydrogenation reaction can be carried out in a rocket kerosene fractionation tower. The operating conditions of the rocket kerosene fractionation tower include: a bottom temperature of 240~320℃, a top temperature of 140~160℃, and a bottom pressure of 0.7~1.6MPa.

[0034] In some specific implementations, the mass ratio of the coal indirect liquefaction Fischer-Tropsch synthesis fraction to the coal direct liquefaction fraction can be 20:80, 21:89, 22:88, 23:87, 24:86, 25:75, 30:70, 35:65, 40:60, etc.

[0035] In this invention, the mass ratio of the coal indirect liquefaction Fischer-Tropsch synthesis fraction to the coal direct liquefaction fraction can be further preferred to be (25~35):(75~65).

[0036] In this invention, the initial boiling point of the coal indirect liquefaction Fischer-Tropsch synthesis fraction is 150-170℃, and the final boiling point is 290-310℃. Within this boiling range, the coal indirect liquefaction Fischer-Tropsch synthesis fraction is characterized by high alkane content, high viscosity, and high calorific value. The initial boiling point of the coal direct liquefaction fraction is 160-180℃, and the final boiling point is 300-320℃. Within this boiling range, the coal direct liquefaction fraction is characterized by high cycloalkanes content and high density. Blending the coal indirect liquefaction Fischer-Tropsch synthesis fraction and the coal direct liquefaction fraction yields a product whose composition, density, viscosity, and calorific value all meet the performance requirements of rocket kerosene.

[0037] In this invention, the Fischer-Tropsch synthesis fraction of indirect coal liquefaction and the direct coal liquefaction fraction can be mixed and dispersed in a stirrer at 700-900 rpm for 40-70 minutes at normal temperature and pressure.

[0038] The operating conditions for the deep hydrogenation refining reaction described in this invention include: a reaction temperature of 300~365℃, preferably 325~345℃; a reaction pressure of 7~13MPa, preferably 11~14MPa; and a volume hourly space velocity of 1~2.5h⁻¹. -1 Preferably 1~1.6h -1 The hydrogen-to-oil ratio is 400-800, preferably 700-800. Through deep hydrorefining, the gum content and acidity in the mixed oil of coal indirect liquefaction Fischer-Tropsch synthesis fraction and coal direct liquefaction fraction can be further reduced, which is more conducive to long-term storage.

[0039] The catalyst used in the deep hydrogenation refining reaction of the present invention includes a support and an active component supported on the support. The support is at least one of silicon oxide, aluminum oxide and titanium oxide, preferably aluminum oxide and silicon oxide. The active component is at least one of cobalt, platinum, palladium, nickel, tungsten and molybdenum, preferably platinum and nickel.

[0040] The method for preparing the Fischer-Tropsch synthesis fraction from coal indirect liquefaction according to the present invention includes: 1) The Fischer-Tropsch synthesis oil from indirect coal liquefaction is subjected to a first fractionation process to obtain the fraction with an initial boiling point of 35-45℃ and a final boiling point of 160-170℃. This fraction is then subjected to a first hydrorefining reaction to obtain hydrorefined tail oil. 2) The hydrorefined tail oil is subjected to a first hydrocracking reaction and then a second fractionation to obtain the coal indirect liquefaction Fischer-Tropsch synthesis fraction.

[0041] In the above preparation method, the indirect coal liquefaction Fischer-Tropsch synthesis oil is produced by gasifying coal into syngas and then reacting it with a catalyst to generate liquid hydrocarbon oil. The catalyst for the above indirect coal liquefaction Fischer-Tropsch synthesis reaction is an Fe-based catalyst, and the reaction conditions include: a temperature of 200~350℃, preferably 280℃, and a pressure of 1~5MPa, preferably 2MPa.

[0042] In this invention, the content of C5-C100 alkanes in the coal indirect liquefaction Fischer-Tropsch synthesis oil can be 80-99.9 vol%, preferably, the content of n-alkanes in the C5-C100 alkanes is greater than or equal to 90 vol.

[0043] The first hydrorefining reaction described in this invention is carried out in a first hydrorefining reactor. The operating conditions of the first hydrorefining reactor may include: an inlet temperature of 270~320℃, preferably 290~310℃; an outlet temperature of 360~400℃, preferably 370~400℃; a reaction pressure of 6~10MPa, preferably 6~8MPa; and a volume hourly space velocity of 2~4h. -1 Preferably 2~3h -1The hydrogen-to-oil ratio is 300-700, preferably 350-550.

[0044] In this invention, the Fischer-Tropsch synthetic oil from coal indirect liquefaction undergoes a first fractionation process, with the fraction having an initial boiling point of 300-355℃ and a final boiling point of 690-735℃. This fraction is then subjected to a first hydrorefining reaction to obtain hydrorefined tail oil. The first fractionation can be carried out in a first fractionation tower, where the top and end-of-pipe products are extracted to obtain the hydrorefined tail oil. The operating conditions of the first fractionation tower include: a bottom temperature of 240-290℃, a bottom pressure of 0.5-1.8 MPa, and a top temperature of 120-150℃. In this invention, the coal indirect liquefaction Fischer-Tropsch synthetic oil fraction undergoes a first hydrorefining reaction to remove impurities, desulfurize and denitrify, and saturate unsaturated hydrocarbons.

[0045] The first hydrocracking reaction described in this invention is carried out in a first hydrocracking reactor. The operating conditions of the first hydrocracking reactor include: an inlet temperature of 280~330℃, preferably 300~320℃; an outlet temperature of 380~450℃, preferably 390~410℃; a reaction pressure of 7~13MPa, preferably 7~10MPa; and a volume hourly space velocity of 1~4h. -1 Preferably 1~2.5h -1 The hydrogen-to-oil ratio is 300-700, preferably 400-600. In this invention, the hydrorefined tail oil undergoes a first hydrocracking reaction to decompose and crack the heavy, inferior product into a light, qualified product.

[0046] The second fractionation described in this invention can be carried out in a second fractionation column. The operating conditions of the second fractionation column include: a bottom temperature of 260~300℃, preferably 260~290℃, a bottom pressure of 0.9~2.1MPa, preferably 1~2MPa, and a top temperature of 140~170℃, preferably 145~165℃.

[0047] In this invention, the initial boiling point of the coal-to-coal liquefaction Fischer-Tropsch synthesis fraction obtained through the second fractionation is 150-170°C, and the final boiling point is 290-310°C; preferably, the initial boiling point is 155-165°C, and the final boiling point is 295-305°C; more preferably, the boiling range is 160-300°C. The coal-to-coal liquefaction Fischer-Tropsch synthesis fraction within the above-mentioned preferred boiling range has high alkane content, high viscosity, and high calorific value.

[0048] In some specific implementations, the preparation method of the coal indirect liquefaction Fischer-Tropsch synthesis fraction can be as follows: The coal indirect liquefaction Fischer-Tropsch synthesis oil produced by the coal indirect liquefaction Fischer-Tropsch synthesis reaction is subjected to a first fractionation in a first fractionation tower. The fraction with a distillation range of 40-165℃ is subjected to a first hydrorefining reaction to obtain hydrorefined tail oil. The hydrorefined tail oil is further subjected to a first hydrocracking reaction. The reaction product of the first hydrocracking reaction is subjected to a second fractionation in a second fractionation tower. The fraction with a distillation range of 195-255℃ is obtained to obtain the coal indirect liquefaction Fischer-Tropsch synthesis fraction.

[0049] The method for preparing direct coal liquefaction fractions according to the present invention includes: 1) After the direct coal liquefaction oil undergoes a hydrogenation stabilization reaction, a hydrogenated stabilized fraction is obtained through a third fractionation. The initial boiling point of the hydrogenated stabilized fraction is 40~80℃, and the final boiling point is 340~400℃. 2) The hydrogenated stable fraction is subjected to a second hydrogenation refining reaction and a second hydrogenation cracking reaction in sequence, and then the direct coal liquefaction fraction is obtained by a fourth fractionation.

[0050] In the above preparation, the raw material coal direct liquefaction oil is a liquid hydrocarbon oil obtained by the coal direct liquefaction process. This coal direct liquefaction process uses coal as raw material and, under high temperature and high pressure conditions, converts solid coal into a liquid hydrocarbon mixture by adding hydrogen and a catalyst. The catalyst used in the above coal direct liquefaction reaction can be an Fe-based catalyst, and the reaction conditions can be: temperature 450℃ and pressure 15MPa.

[0051] The conditions for the hydrogenation stabilization reaction described in this invention include: a reaction temperature of 340~400℃, preferably 350~380℃, a reaction pressure of 3~9MPa, preferably 5~8MPa, and a volume hourly space velocity of 0.5~2.5h⁻¹. -1 Preferably 1~2h -1 The hydrogen-to-oil ratio is 200-700, preferably 300-500. In this invention, the stability of the direct coal liquefaction oil is improved through a hydrogenation stabilization reaction, which prevents polymerization and coking, and initially removes heteroatoms.

[0052] The third fractionation described in this invention can be carried out in a third fractionation column. The operating conditions of the third fractionation column include: a bottom temperature of 370~420℃, a top temperature of 140~190℃, and a bottom pressure of 0.7~2.2MPa. The boiling range of the hydrogenated stable fraction obtained through the third fractionation can be an initial boiling point of 40~80℃ and a final boiling point of 340~400℃, preferably 65~360℃.

[0053] The second hydrorefining reaction of the present invention is carried out in a second hydrorefining reactor. The operating conditions of the second hydrorefining reactor include: an inlet temperature of 300~350℃, preferably 300~320℃; an outlet temperature of 400~450℃, preferably 400~430℃; a reaction pressure of 2~9MPa, preferably 4~8MPa; and a volume hourly space velocity of 0.5~3h. -1 Preferably 0.5~1h -1 The hydrogen-to-oil ratio is 200-700, preferably 400-600. In this invention, the hydrogenated stable fraction undergoes a second hydrogenation refining reaction to achieve aromatic saturation and deep removal of heteroatoms.

[0054] The second hydrocracking reaction of the present invention is carried out in a second hydrocracking reactor. The operating conditions of the second hydrocracking reactor include: an inlet temperature of 280~310℃, preferably 280~300℃; an outlet temperature of 400~450℃, preferably 410~420℃; a reaction pressure of 2~7MPa, preferably 3~5MPa; and a volume hourly space velocity of 0.5~4h. -1 Preferably, it is 1.5~2.5h. -1 The hydrogen-to-oil ratio is 200-700, preferably 300-600. In this invention, the product of the second hydrorefining reaction is subjected to a second hydrocracking reaction to open the ring of cycloalkanes, thereby improving the product composition and quality.

[0055] The fourth fractionation described in this invention can be carried out in a fourth fractionation column. The operating conditions of the fourth fractionation column include: a bottom temperature of 360~400℃, preferably 360~380℃, a top temperature of 140~180℃, preferably 160~180℃, and a bottom pressure of 0.5~2MPa, preferably 0.8~1MPa.

[0056] In this invention, the initial boiling point of the direct coal liquefaction fraction obtained after the fourth fractionation is 160~180℃, and the final boiling point is 300~320℃; preferably, the initial boiling point is 165~175℃, and the final boiling point is 305~315℃; more preferably, the boiling range is 170~310℃. The direct coal liquefaction fraction within the above-mentioned preferred boiling range has high cycloalkanes content and high density.

[0057] In some specific implementations, the preparation method of direct coal liquefaction fraction can be as follows: the direct coal liquefaction oil is subjected to a hydrogenation stabilization reaction; the reaction product of the hydrogenation stabilization reaction is subjected to a third fractionation in a third distillation tower; the fraction with a distillation range of 65~360℃ is subjected to a second hydrogenation stabilization reaction; the reaction product of the second hydrogenation stabilization reaction is subjected to a second hydrogenation cracking reaction; finally, the reaction product of the second hydrogenation cracking reaction is subjected to a fourth fractionation in a fourth distillation tower; the fraction with a distillation range of 170~310℃ is obtained to obtain the direct coal liquefaction fraction.

[0058] The following examples further illustrate the preparation method of coal-based rocket kerosene according to the present invention. These examples are implemented based on the technical solution of the present invention, providing detailed implementation methods and specific operating procedures; however, the scope of protection of the present invention is not limited to the following examples.

[0059] Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods in the art. Unless otherwise specified, the experimental materials used in the following embodiments are commercially available.

[0060] Example 1 according to Figure 1 The process for preparing rocket kerosene is as follows: 1) The coal-to-water Fischer-Tropsch synthesis oil produced from the coal-to-water Fischer-Tropsch indirect liquefaction reactor 1 is sent to the first fractionation tower 2 for first fractionation. The fraction with a distillation range of 35~160℃ is taken into the first hydrorefining reactor 3, and the inlet temperature is controlled at 310℃, the outlet temperature at 400℃, the reaction pressure at 8MPa, and the volumetric space velocity at 3h. -1 The first hydrorefining reaction was carried out under a hydrogen-to-oil ratio of 500 to obtain hydrorefined tail oil. The hydrorefined tail oil was further fed into the first hydrocracking reactor 4, with the inlet temperature controlled at 320℃, the outlet temperature at 410℃, the reaction pressure at 10MPa, and the volume hourly space velocity at 2.5h⁻¹. -1 The first hydrocracking reaction was carried out under the condition of a hydrogen-to-oil ratio of 570. The reaction product of the first hydrocracking reaction was sent to the second fractionation tower 5 for the second fractionation. The fraction with a distillation range of 160~300℃ was taken to obtain the coal indirect liquefaction Fischer-Tropsch synthesis fraction. 2) The coal direct liquefaction oil produced from coal direct liquefaction reactor 6 is sent to hydrogenation stabilization reactor 7, where it is heated at 370℃, pressure 6MPa, and volumetric hourly space velocity (VHSV) 1.5h. -1 After a hydrogenation stabilization reaction is carried out at a hydrogen-to-oil ratio of 400, the reaction product is sent to the third fractionation column 8 for third fractionation. The fraction with a distillation range of 65-360℃ is taken as the hydrogenation stabilization fraction. The hydrogenation stabilization fraction is further processed in the second hydrogenation refining reactor 9, with the inlet temperature controlled at 320℃, the outlet temperature at 430℃, the reaction pressure at 6MPa, and the volume hourly space velocity at 1h. -1 The second hydrorefining reaction was carried out under a hydrogen-to-oil ratio of 400. The reaction products of the second hydrorefining reaction were then fed into the second hydrocracking reactor 10, with the inlet temperature controlled at 300℃, the outlet temperature at 420℃, the reaction pressure at 5MPa, and the volume hourly space velocity at 1.5h⁻¹. -1 The second hydrocracking reaction is carried out under the condition of hydrogen-to-oil ratio of 450. The reaction product of the second hydrocracking reaction is sent to the fourth fractionation tower 11 for fourth fractionation. The fraction with a distillation range of 170~310℃ is taken to obtain the direct coal liquefaction fraction. 3) The Fischer-Tropsch synthesis fraction from indirect coal liquefaction and the direct coal liquefaction fraction were mixed in mixing tank 12 at a mass ratio of 35:65. The mixture was then mechanically stirred at 700 rpm for 40 minutes at ambient temperature and pressure to obtain a mixed oil. This mixed oil was then sent to a mixed oil hydrorefining reactor 13, where the internal temperature was 345℃, the pressure was 13 MPa, and the volumetric hourly space velocity (VHSV) was 1.6 h⁻¹. -1 Under the condition of a hydrogen-to-oil ratio of 800, a deep hydrorefining reaction is carried out. The product of the deep hydrorefining reaction is sent to rocket kerosene fractionation tower 14. Fractionation is carried out under the conditions of a bottom temperature of 280℃, a top temperature of 150℃, and a bottom pressure of 1MPa. The fraction with a distillation range of 195~255℃ is taken to obtain rocket kerosene 15.

[0061] Example 2 1) The coal-to-liquidation Fischer-Tropsch synthesis oil produced from the coal-to-liquidation Fischer-Tropsch synthesis reactor 1 is sent to the first fractionation tower 2 for first fractionation. The fraction with a distillation range of 45~170℃ is taken into the first hydrorefining reactor 3, and the inlet temperature is controlled at 290℃, the outlet temperature at 370℃, the reaction pressure at 6MPa, and the volume hourly space velocity at 2h. -1 The first hydrorefining reaction was carried out under a hydrogen-to-oil ratio of 400 to obtain hydrorefined tail oil. The hydrorefined tail oil was further fed into the first hydrocracking reactor 4, with the inlet temperature controlled at 300℃, the outlet temperature at 390℃, the reaction pressure at 7MPa, and the volume hourly space velocity at 2h⁻¹. -1 The first hydrocracking reaction is carried out under the condition of a hydrogen-to-oil ratio of 500. The reaction product of the first hydrocracking reaction is sent to the second fractionation tower 5 for the second fractionation. The fraction with a distillation range of 165~305℃ is taken to obtain the coal indirect liquefaction Fischer-Tropsch synthesis fraction. 2) The coal direct liquefaction oil produced from coal direct liquefaction reactor 6 is sent to hydrogenation stabilization reactor 7, where it is heated at 370℃, pressure 6MPa, and volumetric hourly space velocity (VHSV) 1.5h. -1 After a hydrogenation stabilization reaction is carried out at a hydrogen-to-oil ratio of 400, the reaction product is sent to the third fractionation column 8 for third fractionation. The fraction with a distillation range of 65-360℃ is taken as the hydrogenation stabilization fraction. The hydrogenation stabilization fraction is further processed in the second hydrogenation refining reactor 9, with the inlet temperature controlled at 300℃, the outlet temperature at 400℃, the reaction pressure at 4MPa, and the volume hourly space velocity at 0.5h⁻¹. -1 The second hydrorefining reaction was carried out under a hydrogen-to-oil ratio of 400. The reaction products of the second hydrorefining reaction were then fed into the second hydrocracking reactor 10, with the inlet temperature controlled at 300℃, the outlet temperature at 420℃, the reaction pressure at 5MPa, and the volume hourly space velocity at 2.5h⁻¹. -1The second hydrocracking reaction is carried out under the condition of a hydrogen-to-oil ratio of 550. The reaction product of the second hydrocracking reaction is sent to the fourth fractionation tower 11 for fourth fractionation. The fraction with a distillation range of 165~305℃ is taken to obtain the direct coal liquefaction fraction. 3) The Fischer-Tropsch synthesis fraction from indirect coal liquefaction and the direct coal liquefaction fraction are mixed in mixing tank 12 at a mass ratio of 30:70. The mixture is then mechanically stirred at 700 rpm for 40 minutes at ambient temperature and pressure to obtain a mixed oil. This mixed oil is then sent to a mixed oil hydrorefining reactor 13, where the internal temperature is 325℃, the pressure is 11 MPa, and the volumetric hourly space velocity (VHSV) is 1 h⁻¹. -1 Deep hydrorefining reaction is carried out under the condition of hydrogen-to-oil ratio of 600. The product of deep hydrorefining reaction is sent to rocket kerosene fractionation tower 14. Fractionation is carried out under the conditions of bottom temperature of 250℃, top temperature of 140℃, and bottom pressure of 0.7MPa. The fraction with a distillation range of 190~250℃ is taken to obtain rocket kerosene 15.

[0062] Example 3 1) The coal-to-liquidation Fischer-Tropsch synthesis oil produced from the coal-to-liquidation Fischer-Tropsch synthesis reactor 1 is sent to the first fractionation tower 2 for first fractionation. The fraction with a distillation range of 40~165℃ is taken into the first hydrorefining reactor 3, and the inlet temperature is controlled at 300℃, the outlet temperature at 385℃, the reaction pressure at 7MPa, and the volume hourly space velocity at 2h. -1 The first hydrorefining reaction was carried out under a hydrogen-to-oil ratio of 450 to obtain hydrorefined tail oil. The hydrorefined tail oil was further fed into the first hydrocracking reactor 4, with the inlet temperature controlled at 310℃, the outlet temperature at 400℃, the reaction pressure at 9MPa, and the volume hourly space velocity at 2.5h⁻¹. -1 The first hydrocracking reaction was carried out under the condition of a hydrogen-to-oil ratio of 550. The reaction product of the first hydrocracking reaction was sent to the second fractionation tower 5 for the second fractionation. The fraction with a distillation range of 155~295℃ was taken to obtain the coal indirect liquefaction Fischer-Tropsch synthesis fraction. 2) The coal direct liquefaction oil produced from coal direct liquefaction reactor 6 is sent to hydrogenation stabilization reactor 7, where it is heated at 370℃, pressure 6MPa, and volumetric hourly space velocity (VHSV) 1.5h. -1 After a hydrogenation stabilization reaction is carried out at a hydrogen-to-oil ratio of 400, the reaction product is sent to the third fractionation column 8 for third fractionation. The fraction with a distillation range of 65-360℃ is taken as the hydrogenation stabilization fraction. The hydrogenation stabilization fraction is further processed in the second hydrogenation refining reactor 9, with the inlet temperature controlled at 310℃, the outlet temperature at 420℃, the reaction pressure at 5MPa, and the volume hourly space velocity at 1h. -1The second hydrorefining reaction was carried out under a hydrogen-to-oil ratio of 400. The reaction products of the second hydrorefining reaction were then fed into the second hydrocracking reactor 10. The inlet temperature was controlled at 290°C, the outlet temperature at 415°C, the reaction pressure at 4 MPa, and the volume hourly space velocity at 2 h⁻¹. -1 The second hydrocracking reaction is carried out under the condition of hydrogen-to-oil ratio of 450. The reaction product of the second hydrocracking reaction is sent to the fourth fractionation tower 11 for fourth fractionation. The fraction with a distillation range of 175~315℃ is taken to obtain the direct coal liquefaction fraction. 3) The Fischer-Tropsch synthesis fraction from indirect coal liquefaction and the direct coal liquefaction fraction were mixed in mixing tank 12 at a mass ratio of 25:75. The mixture was then mechanically stirred at 700 rpm for 40 minutes at ambient temperature and pressure to obtain a mixed oil. This mixed oil was then sent to a mixed oil hydrorefining reactor 13, where the internal temperature was 335℃, the pressure was 11 MPa, and the volumetric hourly space velocity (VHSV) was 1.2 h⁻¹. -1 Under the condition of a hydrogen-to-oil ratio of 750, a deep hydrorefining reaction is carried out. The product of the deep hydrorefining reaction is sent to rocket kerosene fractionation tower 14. Fractionation is carried out under the conditions of a bottom temperature of 310℃, a top temperature of 160℃, and a bottom pressure of 1.5MPa. The fraction with a distillation range of 200~260℃ is taken to obtain rocket kerosene 15.

[0063] Example 4 The difference from Example 1 is that during the second fractionation in the second fractionation tower 5, the fraction with a distillation range of 150~290℃ is taken as the Fischer-Tropsch synthesis fraction for indirect coal liquefaction.

[0064] Example 5 The difference from Example 1 is that when the second fractionation is carried out in the second fractionation tower 5, the fraction with a distillation range of 170~310℃ is taken as the Fischer-Tropsch synthesis fraction of coal indirect liquefaction.

[0065] Example 6 The difference from Example 1 is that when the second fractionation is carried out in the second fractionation tower 5, the fraction with a distillation range of 150~310℃ is taken as the Fischer-Tropsch synthesis fraction of coal indirect liquefaction.

[0066] Example 7 The difference from Example 1 is that when the fourth fractionation is carried out in the fourth fractionation tower 11, the fraction with a distillation range of 160~300℃ is taken as the direct coal liquefaction fraction.

[0067] Example 8 The difference from Example 1 is that when the fourth fractionation is carried out in the fourth fractionation tower 11, the fraction with a distillation range of 180~320℃ is taken as the direct coal liquefaction fraction.

[0068] Example 9 The difference from Example 1 is that when the fourth fractionation is carried out in the fourth fractionation tower 11, the fraction with a distillation range of 160~320℃ is taken as the direct coal liquefaction fraction.

[0069] Example 10 The difference from Example 1 is that the Fischer-Tropsch synthesis fraction from indirect coal liquefaction and the direct coal liquefaction fraction are mixed at a mass ratio of 20:80.

[0070] Example 11 The difference from Example 1 is that the Fischer-Tropsch synthesis fraction from indirect coal liquefaction and the direct coal liquefaction fraction are mixed at a mass ratio of 40:60.

[0071] Example 12 The difference from Example 1 is that the product of the deep hydrogenation refining reaction is fractionated and the fraction with a distillation range of 185~245℃ is taken as coal-based rocket kerosene.

[0072] Example 13 The difference from Example 1 is that the product of the deep hydrogenation refining reaction is fractionated and the fraction with a distillation range of 205~265℃ is taken as coal-based rocket kerosene.

[0073] Comparative Example 1 The difference from Example 1 is that the Fischer-Tropsch synthesis fraction from indirect coal liquefaction and the direct coal liquefaction fraction are mixed at a mass ratio of 10:90.

[0074] Comparative Example 2 The difference from Example 1 is that the Fischer-Tropsch synthesis fraction from indirect coal liquefaction and the direct coal liquefaction fraction are mixed at a mass ratio of 50:50.

[0075] Comparative Example 3 The difference from Example 1 is that when the second fractionation is carried out in the second fractionation tower 5, the fraction with a distillation range of 140~270℃ is taken as the Fischer-Tropsch synthesis fraction of coal indirect liquefaction.

[0076] Comparative Example 4 The difference from Example 1 is that during the second fractionation in the second fractionation tower 5, the fraction with a distillation range of 180~330℃ is taken as the Fischer-Tropsch synthesis fraction for indirect coal liquefaction.

[0077] Comparative Example 5 The difference from Example 1 is that when the fourth fractionation is carried out in the fourth fractionation tower 11, the fraction with a distillation range of 150~280℃ is taken as the direct coal liquefaction fraction.

[0078] Comparative Example 6 The difference from Example 1 is that when the fourth fractionation is carried out in the fourth fractionation tower 11, the fraction with a distillation range of 190~340℃ is taken as the direct coal liquefaction fraction.

[0079] Comparative Example 7 The difference from Example 1 is that the product of the deep hydrogenation refining reaction is fractionated and the fraction with a distillation range of 160~210℃ is taken as coal-based rocket kerosene.

[0080] The properties of the distillate oils obtained from Test Examples 1-13 and Comparative Examples 1-7 are shown in Table 1 below.

[0081] Table 1

[0082] As can be seen from the results in Table 1, the embodiment of preparing rocket kerosene by coupling direct coal liquefaction products and indirect coal liquefaction products of the present invention and then hydrogenating and refining them can solve the shortcomings of high density, low viscosity and low calorific value of rocket kerosene prepared from direct coal liquefaction kerosene, expand the range of raw materials and methods for preparing rocket kerosene, and expand the scope of application of coal-based products.

[0083] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for preparing coal-based rocket kerosene, characterized in that, The method includes: mixing the Fischer-Tropsch synthesis fraction of indirect coal liquefaction and the direct coal liquefaction fraction, subjecting them to a deep hydrogenation refining reaction, and then fractionating them to obtain the coal-based rocket kerosene by taking the fraction with an initial boiling point of 185~205℃ and a final boiling point of 245~265℃. The mass ratio of the coal indirect liquefaction Fischer-Tropsch synthesis fraction to the coal direct liquefaction fraction is (20~40):(80~60); the initial boiling point of the coal indirect liquefaction Fischer-Tropsch synthesis fraction is 150~170℃, and the final boiling point is 290~310℃; the initial boiling point of the coal direct liquefaction fraction is 160~180℃, and the final boiling point is 300~320℃.

2. The preparation method according to claim 1, characterized in that, The mass ratio of the coal indirect liquefaction Fischer-Tropsch synthesis fraction to the coal direct liquefaction fraction is (25~35):(75~65).

3. The preparation method according to claim 1 or 2, characterized in that, The operating conditions for the deep hydrogenation refining reaction include: a reaction temperature of 300–365 °C, a reaction pressure of 7–13 MPa, and a volume hourly space velocity of 1–2.5 h⁻¹. -1 The hydrogen-to-oil ratio is 400-800.

4. The preparation method according to any one of claims 1-3, characterized in that, The catalyst for the deep hydrorefining reaction includes a support and an active component supported on the support. The support is at least one of silicon oxide, aluminum oxide, and titanium oxide, and the active component is at least one of cobalt, platinum, palladium, nickel, tungsten, and molybdenum.

5. The preparation method according to any one of claims 1-4, characterized in that, The method for preparing the Fischer-Tropsch synthesis fraction from coal indirect liquefaction includes: 1) The Fischer-Tropsch synthesis oil from indirect coal liquefaction is subjected to a first fractionation process to obtain the fraction with an initial boiling point of 35-45℃ and a final boiling point of 160-170℃. This fraction is then subjected to a first hydrorefining reaction to obtain hydrorefined tail oil. 2) The hydrorefined tail oil is subjected to a first hydrocracking reaction and then a second fractionation to obtain the coal indirect liquefaction Fischer-Tropsch synthesis fraction.

6. The preparation method according to claim 5, characterized in that, The first hydrorefining reaction is carried out in a first hydrorefining reactor, the operating conditions of which include: inlet temperature of 270~320℃, outlet temperature of 360~400℃, reaction pressure of 6~10MPa, and volume hourly space velocity of 2~4h. -1 The hydrogen-to-oil ratio is 300-700; and / or The first fractionation is carried out in a first fractionation column, the operating conditions of which include: bottom temperature of 240~290℃, bottom pressure of 0.5~1.8MPa, and top temperature of 120~150℃; and / or The first hydrocracking reaction is carried out in a first hydrocracking reactor, the operating conditions of which include: inlet temperature of 280~330℃, outlet temperature of 380~450℃, reaction pressure of 7~13MPa, and volume hourly space velocity of 1~4h. -1 The hydrogen-to-oil ratio is 300-700; and / or The second fractionation is carried out in the second fractionation column, and the operating conditions of the second fractionation column include: bottom temperature of 260~300℃, bottom pressure of 0.9~2.1MPa, and top temperature of 140~170℃.

7. The preparation method according to claim 5, characterized in that, The C5-C100 alkanes in the coal-to-liquidation Fischer-Tropsch synthesis oil contain 80-99.9 vol% of alkanes. Preferably, the content of n-alkanes in the C5-C100 alkanes is greater than or equal to 90 vol.

8. The preparation method according to any one of claims 1-4, characterized in that, The method for preparing the direct coal liquefaction fraction includes: 1) After the direct coal liquefaction oil undergoes a hydrogenation stabilization reaction, a hydrogenated stabilized fraction is obtained through a third fractionation. The initial boiling point of the hydrogenated stabilized fraction is 40~80℃, and the final boiling point is 340~400℃. 2) The hydrogenated stable fraction is subjected to a second hydrogenation refining reaction and a second hydrogenation cracking reaction in sequence, and then the direct coal liquefaction fraction is obtained by a fourth fractionation.

9. The preparation method according to claim 8, characterized in that, The operating conditions for the hydrogenation stabilization reaction include: a temperature of 340–400°C and a pressure of 3–9 MPa; and / or The second hydrorefining reaction is carried out in a second hydrorefining reactor, the operating conditions of which include: inlet temperature of 300-350°C, outlet temperature of 400-450°C, reaction pressure of 2-9 MPa, and volume hourly space velocity of 0.5-3 h⁻¹. -1 The hydrogen-to-oil ratio is 200-700; and / or The second hydrocracking reaction is carried out in a second hydrocracking reactor, the operating conditions of which include: inlet temperature of 280~310℃, outlet temperature of 400~450℃, reaction pressure of 2~7MPa, and volume hourly space velocity of 0.5~4h. -1 The hydrogen-to-oil ratio is 200-700.

10. The preparation method according to claim 8 or 9, characterized in that, The third fractionation is carried out in a third fractionation column, and the operating conditions of the third fractionation column include: a bottom temperature of 370~420℃, a top temperature of 140~190℃, and a bottom pressure of 0.7~2.2MPa; and / or The fourth fractionation is carried out in a fourth fractionation column, and the operating conditions of the fourth fractionation column include: bottom temperature of 360~400℃, top temperature of 140~180℃, and bottom pressure of 0.5~2MPa.

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