Method and apparatus for producing bio-jet fuel

Abstract

The application provides a method for producing bio-jet fuel, comprising the following steps: mixing oil and fat raw material with petroleum-based jet fuel, and then carrying out one-stage hydrogenation with hydrogen, and separating to obtain one-stage hydrogenated refined oil and one-stage hydrogenated light component; detecting the composition of the one-stage hydrogenated refined oil and carrying out the following operations: operation one, separating the petroleum-based jet fuel in the one-stage hydrogenated refined oil, and separating the one-stage hydrogenated light component to obtain vacuum oil, wherein the vacuum oil is recycled as raw material for producing bio-jet fuel, and a part of the one-stage hydrogenated refined oil is recycled as diluent, and another part of the one-stage hydrogenated refined oil is used as raw material to carry out two-stage hydrogenation to obtain two-stage hydrogenated material; operation two, in other cases, the one-stage hydrogenated refined oil is recycled as diluent; the two-stage hydrogenated material is separated to obtain two-stage oil phase material, the two-stage oil phase material is subjected to hydrogenation rectification to obtain a product, and the second separation and the third separation are carried out by vacuumizing respectively. The application also provides a device for producing bio-jet fuel.

Description

Technical Field

[0001] This invention belongs to the technical field of producing bio-jet fuel, and specifically relates to a method and apparatus for producing bio-jet fuel. Background Technology

[0002] The complete technology (SRJET technology) for producing bio-jet kerosene from oil and fat feedstocks, developed by the Research Institute of Petroleum Processing of China Petroleum & Chemical Corporation, adopts a two-stage hydrogenation process. The first stage is the hydrogenation treatment of oil and fat feedstocks to remove oxygen and other heteroatoms from the feedstocks to obtain hydrogenated refined oil. The second stage is the hydrogenation conversion of the hydrogenated refined oil to adjust the distillation range distribution and lower the freezing point of the product. Then, the product is separated to obtain bio-jet kerosene that meets the quality requirements.

[0003] Some oily feedstocks (such as waste cooking oil) have a high oxygen content (around 12% by mass). During the first-stage hydrodeoxygenation process, a large amount of heat is released. To ensure the safe and stable operation of the hydrorefining process for oily feedstocks and to protect the catalyst and reactor, a large amount of petroleum-based jet fuel is required as a diluent during the initial startup of the bio-jet fuel unit (dilution to waste cooking oil mass ratio greater than or equal to 5:1). After the oily feedstocks (such as waste cooking oil) are fed in, the first-stage hydrorefining unit processes the waste cooking oil into first-stage hydrorefined oil. This first-stage hydrorefined oil can then be used as a diluent for the first-stage hydrorefining reaction system. To produce a pure bio-jet fuel product that meets standards (pure HEFA-SPK) and ensures that the bio-jet fuel product complies with the quality assurance system, the petroleum-based jet fuel added during the initial startup needs to be separated from the unit. When the fraction below 230°C in the first-stage hydrorefined oil is less than 10%, the aromatic content is less than 1%, and the alkanes content is greater than 85%, the petroleum-based jet fuel and the bio-based refined oil can be considered completely separated.

[0004] The existing method for separating petroleum-based jet fuel added during the initial startup phase from the unit involves separating it in the hydrodistillation column of the second-stage hydrotreating unit. Utilizing the differences in distillation range and other properties between petroleum-based jet fuel and bio-based hydrorefined oil, the separated petroleum-based jet fuel is discharged from the unit via a side stream from the hydrodistillation column, ensuring complete separation. However, this method has several drawbacks: due to the different physical properties of petroleum-based jet fuel and refined oil, the bottom temperature of the distillation column is high (approximately 330°C) during separation. This high-temperature separation makes the distillation column particularly prone to "sudden boiling" (similar to the separation of oil and water in everyday life). This sudden boiling causes the liquid level in the distillation column to fluctuate wildly between 0% and 100%, making the bottom pump extremely susceptible to cavitation and causing significant fluctuations in the flow rate of the reboiler at the bottom of the distillation column, posing a risk of dry burning of the furnace tubes.

[0005] Furthermore, the separation of petroleum-based jet fuel and bio-based hydrorefined oil using a distillation column takes a relatively long time and consumes a large amount of bio-based oil and fat raw materials. The procurement cost of these raw materials (e.g., waste cooking oil) is relatively high, resulting in waste of bio-based raw materials. Additionally, the use of fuel gas in the distillation column leads to higher energy consumption for the unit. Summary of the Invention

[0006] In order to overcome the shortcomings of the prior art, one of the objectives of the present invention is to provide a method for producing bio-jet fuel. By using the above-mentioned method for producing bio-jet fuel, it is possible to achieve safe, stable and efficient separation of petroleum-based jet fuel and bio-based hydrorefined oil, and solve the problems of large fluctuations, high difficulty and high risk in distillation columns when using distillation columns for separation.

[0007] The second objective of this invention is to provide an apparatus for producing bio-jet fuel. Using the above-mentioned apparatus for producing bio-jet fuel, it is possible to achieve safe, stable and efficient separation of petroleum-based jet fuel and bio-based hydrorefined oil, solving the problems of large fluctuations, high difficulty and high risk in distillation columns when using distillation columns for separation.

[0008] The third objective of this invention is to provide a method for producing bio-jet fuel using the aforementioned apparatus. This method enables the safe, stable, and efficient separation of petroleum-based jet fuel and bio-based hydrorefined oil, solving the problems of large fluctuations, high difficulty, and high risk associated with separation using a distillation column.

[0009] Therefore, in a first aspect, the present invention provides a method for producing bio-jet fuel, comprising the following steps:

[0010] S1. Oily raw materials and petroleum-based jet fuel (a diluent) are mixed evenly to obtain a mixture;

[0011] S2. The mixture obtained in step S1 and hydrogen are subjected to a hydrogenation process in the presence of a hydrogenation catalyst to obtain a hydrogenated material.

[0012] S3. The hydrogenated material obtained in step S2 is subjected to a first high-pressure separation to obtain gas, a first oil phase material and water. The first oil phase material is further separated to obtain a first hydrotreated refined oil and a first hydrotreated light component.

[0013] S4. Analyze the composition of a section of hydrotreated oil and perform the following operations:

[0014] Operation 1: In the case that the fraction below 230℃ in the first-stage hydrorefined oil is less than 10wt%, the aromatic content is less than 1wt%, and the alkane content is greater than 85wt%, the first-stage hydrorefined light component is separated into gas, vacuum oil, and water in the third stage. The vacuum oil is recycled back to step S1 as a raw material for the production of bio-jet fuel. Part of the first-stage hydrorefined oil is recycled back to step S1 as a diluent, and the other part is used as a raw material for second-stage hydrorefining to obtain second-stage hydrorefined material.

[0015] Operation 2: In all other cases, the entire hydrorefined oil from one stage is recycled back to step S1 as a diluent.

[0016] S5. The second-stage hydrogenated material undergoes a second high-pressure separation to obtain gas and a second-stage oil phase material. The second-stage oil phase material is then separated by hydrodistillation to obtain biojet fuel and biodiesel.

[0017] In step S4, the third separation is performed by vacuuming.

[0018] As a specific embodiment of the present invention, the oily raw materials include one or more of animal fats, vegetable oils, and waste cooking oil.

[0019] As a specific embodiment of the present invention, the mass ratio of the oil-based raw material to the diluent is less than or equal to 1:5, preferably 1:100 to 1:5.

[0020] As a specific embodiment of the present invention, the conditions for the first high-pressure separation include: pressure 6.0 to 7.2 MPa and temperature 20 to 55°C.

[0021] In a specific embodiment of the present invention, the gas and water obtained from the first high-pressure separation are discharged externally.

[0022] As a specific embodiment of the present invention, in step S3, the conditions for the first separation include: pressure -0.08 to 0 MPa.

[0023] As a specific embodiment of the present invention, in step S4, in operation one, based on the first-stage hydrorefined oil, 85wt% to 90wt% of the first-stage hydrorefined oil is recycled back to step S1 as a diluent, and 10wt% to 15wt% is used as raw material for second-stage hydrorefining to obtain second-stage hydrorefined material.

[0024] In a specific embodiment of the present invention, in operation one, both the gas and water obtained from the third separation are discharged.

[0025] In a specific embodiment of the present invention, in step S4, in operation two, the first hydrogenated light component is discharged externally, or the first hydrogenated light component is separated into gas, light sludge oil and water through a second separation, and the gas, light sludge oil and water obtained from the second separation are all discharged externally.

[0026] In a specific embodiment of the present invention, the second separation is performed by vacuuming.

[0027] As a specific embodiment of the present invention, in step S5, the conditions for the second high-pressure separation include a pressure of 6.0 to 7.2 MPa and a temperature of 20 to 55°C.

[0028] In a specific embodiment of the present invention, in step S5, the gas obtained by the second high-pressure separation is used as circulating hydrogen.

[0029] As a specific embodiment of the present invention, the hydrotreating catalyst comprises a metal active component and a support, wherein the support is selected from one or more of alumina, silicon oxide, zirconium oxide, and titanium oxide, and the metal active component is at least one selected from a Group VIB metal element and at least one selected from a Group VIII metal element, wherein the Group VIB metal element is molybdenum and / or tungsten, and the Group VIII metal element is cobalt and / or nickel; based on the total weight of the hydrotreating catalyst, the content of the metal active component, calculated as oxides, is 5 to 50% by weight.

[0030] As a specific embodiment of the present invention, based on the total weight of the hydrotreating catalyst, the content of the Group VIB metal element, calculated as oxide, is 4 to 40% by weight, and the content of the Group VIII metal element is 1 to 10% by weight.

[0031] In a specific embodiment of the present invention, the active metal component contains cobalt and molybdenum.

[0032] As a specific embodiment of the present invention, based on the total weight of the hydrotreating catalyst, the content of the Group VIB metal element, calculated as oxide, is 8-35% by weight, and the content of the Group VIII metal element is 2-5% by weight.

[0033] As a specific embodiment of the present invention, the reaction conditions for the first-stage hydrogenation treatment include: hydrogen partial pressure 6.0–7.2 MPa, reaction temperature 280–320 °C, and volume hourly space velocity 0.21–0.38 h⁻¹. -1 The hydrogen-to-oil volume ratio is 1000–1500.

[0034] As a specific embodiment of the present invention, the reaction conditions for the first-stage hydrogenation treatment are: reaction temperature 290-300℃.

[0035] As a specific embodiment of the present invention, the reaction conditions for the second separation include: hydrogen partial pressure of 6.0–7.2 MPa, reaction temperature of 280–320 °C, and volume hourly space velocity of 0.21–0.38 h⁻¹. -1 The hydrogen-to-oil volume ratio is 1000–1500.

[0036] As a specific embodiment of the present invention, the reaction conditions for the third separation include: hydrogen partial pressure 6.0–7.2 MPa, reaction temperature 280–320 °C, and volume hourly space velocity 0.21–0.38 h⁻¹. -1 The hydrogen-to-oil volume ratio is 1000–1500.

[0037] As a specific embodiment of the present invention, the two-stage hydrotreating process includes hydrocracking isomerization treatment and post-hydrorefining treatment.

[0038] As a specific embodiment of the present invention, the hydrocracking isomerization treatment employs a hydrocracking isomerization catalyst. The hydrocracking isomerization catalyst contains a support and an active metal component supported on the support. The support of the hydrocracking isomerization catalyst contains alumina and silica-alumina. Based on the support, the alumina content is 20-80% by weight, and the silica-alumina content is 80-20% by weight. The active metal component includes platinum and palladium. Based on the total weight of the hydrocracking catalyst, the active metal component content, calculated as oxides, is 0.1-5% by weight.

[0039] As a specific embodiment of the present invention, the conditions for the hydrocracking isomerization treatment include: hydrogen partial pressure 6.0–7.2 MPa, reaction temperature 310–340 °C, and volume hourly space velocity 0.48–0.88 h⁻¹. -1 The hydrogen-to-oil volume ratio is 500–700.

[0040] As a specific embodiment of the present invention, the specific surface area of ​​the hydrocracking isomerization catalyst is greater than or equal to 180 m². 2 / g, pore volume greater than or equal to 0.3ml / g, bulk density 0.58~0.62g / cm³ 3 Equivalent diameter 1.0~1.2mm.

[0041] As a specific embodiment of the present invention, the post-hydrogenation refining process uses a post-hydrogenation refining catalyst.

[0042] As a specific embodiment of the present invention, the post-hydrogenation refining catalyst contains a support and an active metal component supported on the support. The support of the post-hydrogenation refining catalyst contains alumina and silica-alumina. Based on the support, the alumina content is 40-60% by weight, and the silica-alumina content is 60-40% by weight. The active metal component includes platinum and palladium. Based on the total weight of the post-hydrogenation refining catalyst, the active metal component content is 0.1-5% by weight, calculated as oxides.

[0043] As a specific embodiment of the present invention, the specific surface area of ​​the post-hydrogenation refining catalyst is greater than or equal to 250 m². 2 / g, pore volume greater than or equal to 0.4ml / g, bulk density 0.52~0.56g / cm³ 3 The equivalent diameter is 1.2 to 1.4 mm.

[0044] As a specific embodiment of the present invention, the reaction conditions for the post-hydrogenation refining treatment include: a reaction temperature of 170–210°C and a volume hourly space velocity of 0.6–1.1 h⁻¹. -1 The hydrogen-to-oil volume ratio is 500–700, the circulating hydrogen purity is 80–95% (V / V), and the hydrogen partial pressure is 6.0–7.2 MPa.

[0045] Therefore, in a second aspect, the present invention provides an apparatus for producing bio-jet fuel, comprising a first-stage hydrogenation unit and a second-stage hydrogenation unit.

[0046] A hydrogenation unit comprises a hydrogenation reactor, a high-pressure separator, a stripping tower, and a vacuum tower connected in sequence, wherein the hydrogenation reactor is filled with a hydrogenation catalyst.

[0047] The two-stage hydrogenation unit includes a hydrocracking isomerization reactor, a post-hydrorefining reactor, a second high-pressure separator, and a two-stage hydrofractionation system connected in sequence; the hydrocracking isomerization reactor and the post-hydrorefining reactor are respectively filled with hydrocracking isomerization catalyst and post-hydrorefining catalyst.

[0048] The apparatus for producing bio-jet kerosene further includes a detection system, control valves, and a first-stage hydrogenation vacuum system. The first-stage hydrogenation vacuum system comprises a cooler, a vacuum pump, and a vacuum oil-water separator connected in sequence. The cooler is also connected to the vacuum oil-water separator. The vacuum oil-water separator has a circulation side line in its middle section, which is connected to the first-stage hydrogenation unit. A steam valve is installed at the top of the vacuum pump to control the amount of steam entering the vacuum pump. A first valve and a second valve are installed at the bottom of the vacuum tower, and a third valve is installed on the circulation side line. The detection system is used to detect the composition of the components at the bottom of the vacuum tower, and the control valves are used to control the steam valve, the first valve, the second valve, and the third valve based on the detection results of the detection system.

[0049] In this invention, the steam valve controls the vacuum level of the vacuum pump and the amount of hydrogenated light components entering the vacuum pump from the top of the vacuum tower by controlling the amount of steam entering the vacuum pump.

[0050] In this invention, the first valve is used to control the amount of bottom component (i.e., first-stage hydrorefined oil) of the vacuum tower circulating back to the first-stage hydrotreating unit, and the second valve is used to control the amount of bottom component of the vacuum tower entering the second-stage hydrotreating unit for second-stage hydrotreating.

[0051] In this invention, the third valve is used to control the oil phase separated by the vacuum oil-water separator to enter the circulation side stream. That is, the third valve is used to control the circulation volume of the vacuum oil.

[0052] As a specific embodiment of the present invention, the two-stage hydrodistillation system includes a two-stage hydrodistillation column, a bottom reboiler is provided at the bottom of the two-stage hydrodistillation column, and a bio-jet fuel side-stream column is provided at the top of the two-stage hydrodistillation column.

[0053] As a specific embodiment of the present invention, the vacuum oil-water separator is further provided with an external discharge side line in the middle, and a fourth valve is provided on the external discharge side line. The control valve is used to control the fourth valve according to the detection result of the detection system.

[0054] In this invention, the fourth valve is used to control the oil phase separated by the vacuum oil-water separator to enter the external discharge line. Specifically, the fourth valve is used to control the discharge of light sludge oil.

[0055] The control valve of the present invention can achieve the following by controlling the steam valve, the first valve, the second valve, the third valve and the fourth valve: the top of the vacuum tower is connected to the external discharge side line, or the top of the vacuum tower is connected to a cooler and the oil phase in the vacuum oil-water separator enters the external discharge side line, or the top of the vacuum tower is connected to a cooler and the oil phase in the vacuum oil-water separator enters the circulation side line.

[0056] As a specific embodiment of the present invention, an external exhaust side line is provided at the top of the vacuum tower.

[0057] Therefore, in a third aspect, the present invention provides a method for producing bio-jet fuel, using the above-described apparatus for producing bio-jet fuel, comprising the following steps:

[0058] S1. Oily raw materials and petroleum-based jet fuel (a diluent) are mixed evenly to obtain a mixture;

[0059] S2. The mixture obtained in step S1 and hydrogen are fed into a first-stage hydrogenation reactor in the presence of a hydrogenation catalyst to undergo first-stage hydrogenation treatment and obtain first-stage hydrogenated material.

[0060] S3. The hydrogenated material obtained in step S2 enters a high-pressure separator for the first high-pressure separation to obtain gas, a first oil phase material and water. The first oil phase material is then separated by a stripping tower and a vacuum tower to obtain a first hydrotreated refined oil and a first hydrotreated light component.

[0061] S4. The detection system detects the composition of a section of hydrorefined oil and performs the following operations;

[0062] Operation 1: In the case that the fraction below 230℃ in the first-stage hydrorefined oil is less than 10wt%, the aromatic content is less than 1wt%, and the alkane content is greater than 85wt%, the control valve controls the following: the first-stage hydrorefined light component undergoes a third separation through the first-stage hydrorefining vacuum system to obtain gas, vacuum oil, and water. The vacuum oil is recycled back to step S1 as a raw material for the production of bio-jet fuel. Part of the first-stage hydrorefined oil is recycled back to step S1 as a diluent, and the other part is used as a raw material for second-stage hydrorefining to obtain second-stage hydrorefined material.

[0063] Operation 2: In other cases, the control valves control the following: all hydrorefined oil from the first stage is recycled back to step S1 as a diluent; the light components from the first stage are discharged; or, the light components from the first stage undergo a second separation through a first-stage hydrorefining vacuum system to obtain gas, light sludge oil, and water, all of which are discharged.

[0064] S5. The second-stage hydrogenated material is separated into gas and second-stage oil phase material by the second high-pressure separator. The second-stage oil phase material is then hydrodistilled through the second-stage hydrodistillation system to obtain biojet fuel and biodiesel.

[0065] The second separation and the third separation are carried out by a vacuum pump and a vacuum oil-water separator, respectively.

[0066] Beneficial effects of the present invention

[0067] The method and apparatus for producing bio-jet fuel provided by this invention can achieve safe, stable and efficient separation of petroleum-based jet fuel and bio-based hydrorefined oil, solving the problems of large fluctuations, high difficulty and high risk in distillation columns when using distillation columns for separation.

[0068] The method for producing bio-jet fuel provided by this invention separates the petroleum-based jet fuel introduced during the addition of a diluent by vacuuming. Compared with separation by distillation, this method solves the problems of large fluctuations, high difficulty, and high risk associated with separation by distillation column cutting.

[0069] The apparatus for producing bio-jet fuel provided by this invention has an external discharge side line at the vacuum oil-water separator. The new waste oil containing petroleum-based jet fuel is discharged through the vacuum oil-water separator, which can achieve safe, stable and efficient separation of petroleum-based jet fuel and bio-based hydrorefined oil, and solve the problems of large fluctuations, high difficulty and high risk of distillation column when using distillation column for cutting and separation. Attached Figure Description

[0070] Figure 1 This is a flowchart of the apparatus and process for producing bio-jet fuel according to the present invention.

[0071] Figure 2 The apparatus and flow chart for the SRJET process of producing bio-jet fuel.

[0072] Figure 3 Example 1 illustrates the liquid level changes in the vacuum pump during the separation of petroleum-based jet fuel and refined oil using a vacuum system.

[0073] Figure 4 To study the liquid level changes in a distillation column when separating petroleum-based jet fuel and refined oil using a two-stage hydrogenation unit distillation column.

[0074] The components include: 1. Waste cooking oil; 2. First-stage hydrogenation feedstock buffer tank; 3. Compressed hydrogen; 4. First-stage hydrogenation heater; 5. First-stage hydrogenation reactor; 6. Fresh hydrogen; 7. First-stage hydrogenation unit fresh hydrogen compressor; 8. Water; 9. First-stage high-pressure separator; 10. Stripping tower; 11. Waste hydrogen; 12. Vacuum tower; 13. First-stage hydrogenation vacuum system; 14. Water cooler; 15. Steam; 16. Vacuum pump; 17. External exhaust gas; 18. Vacuum oil-water separator; 19. Vacuum oil; 20. Wastewater; 21. First-stage hydrogenation refined oil; 22. Second-stage hydrogenation unit feedstock. 23. Buffer tank; 24. Second-stage hydrogenation heater; 25. Hydrocracking isomerization reactor; 26. Post-hydrogenation refining reactor; 27. Second-stage hydrogenation high-pressure separator; 28. Circulating hydrogen; 29. ​​Second-stage hydrogenation circulating hydrogen compressor; 30. Second-stage hydrogenation distillation column; 31. Second-stage hydrogenation distillation column bottom reboiler; 32. Second-stage hydrogenation distillation column bottom circulating pump; 33. Biodiesel pump; 34. Biodiesel; 35. Biojet fuel side-stream column; 36. Biojet fuel; 37. Second-stage hydrogenation fractionation system; 38. First-stage hydrogenation unit; 39. Second-stage hydrogenation unit; 30. Light sludge oil. Detailed Implementation

[0075] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments are merely illustrative of the invention and should not be considered as specific limitations thereof. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0076] This invention provides a method for producing bio-jet fuel, comprising the following steps:

[0077] S1. Oily raw materials and petroleum-based jet fuel (a diluent) are mixed evenly to obtain a mixture;

[0078] S2. The mixture obtained in step S1 and hydrogen are subjected to a hydrogenation process in the presence of a hydrogenation catalyst to obtain a hydrogenated material.

[0079] S3. The hydrogenated material obtained in step S2 is subjected to a first high-pressure separation to obtain gas, a first oil phase material and water. The gas and water obtained from the first high-pressure separation are discharged. The first oil phase material is separated into a first hydrotreated refined oil and a first hydrotreated light component.

[0080] S4. Detect the composition of a section of hydrotreated oil and perform the following operations;

[0081] Operation 1: In the first stage of hydrorefining, the fraction below 230°C is less than 10 wt%, the aromatic content is less than 1 wt%, and the alkane content is greater than 85 wt%. The first stage hydrorefining light component is separated into gas, vacuum oil, and water in the third stage. The gas and water obtained from the third stage separation are discharged. The vacuum oil is recycled back to step S1 as a raw material for the production of bio-jet fuel. Part of the first stage hydrorefining oil is recycled back to step S1 as a diluent, and the other part is used as a raw material for the second stage hydrorefining process to obtain the second stage hydrorefined material.

[0082] Operation 2: In all other cases, the entire hydrorefined oil from one stage is recycled back to step S1 as a diluent.

[0083] S5. The second-stage hydrogenated material undergoes a second high-pressure separation to obtain gas and a second-stage oil phase material. The gas obtained from the second high-pressure separation is used as circulating hydrogen, and the second-stage oil phase material is separated by distillation to obtain biojet fuel and biodiesel.

[0084] In step S4, the third separation is performed by vacuuming.

[0085] Figure 1 This is a flowchart illustrating the apparatus and process for producing bio-jet kerosene according to the present invention. See also... Figure 1As shown, the present invention provides an apparatus for producing bio-jet kerosene, comprising a first-stage hydrogenation unit 37 and a second-stage hydrogenation unit 38. The first-stage hydrogenation unit 37 includes a first-stage hydrogenation reactor 5, a first-stage high-pressure separator 9, a stripping tower 10, and a vacuum tower 12 connected in sequence; the first-stage hydrogenation reactor 5 is filled with a hydrogenation catalyst. The second-stage hydrogenation unit 38 includes a hydrocracking isomerization reactor 24, a post-hydrocracking refining reactor 25, a second high-pressure separator 26, and a second-stage hydrogenation fractionation system 36 connected in sequence; the hydrocracking isomerization reactor 24 and the post-hydrocracking refining reactor 25 are respectively filled with a hydrocracking isomerization catalyst and a post-hydrocracking refining catalyst. The apparatus for producing bio-jet kerosene also includes a detection system (not shown), control valves (not shown), and a first-stage hydrogenation vacuum system 13, the first-stage hydrogenation vacuum system 13 including a cooling system connected in sequence. The system includes a cooler (i.e., water cooler 14), a vacuum pump 16, and a vacuum oil-water separator 18. The cooler 14 is also connected to the vacuum oil-water separator 18. The vacuum oil-water separator 18 has a circulation side line and an exhaust side line in the middle. The circulation side line is connected to a hydrogenation unit 37. The top of the vacuum pump 16 is equipped with a steam valve (not shown) for controlling the amount of steam entering the vacuum pump. The bottom of the vacuum tower 12 is equipped with a first valve (not shown) and a second valve (not shown). The circulation side line of the vacuum oil-water separator 18 is equipped with a third valve, and the exhaust side line of the vacuum oil-water separator 18 is equipped with a fourth valve (not shown). A detection system is used to detect the composition of the components at the bottom of the vacuum tower 12. Control valves are used to control the steam valve, the first valve, the second valve, the third valve, and the fourth valve according to the detection results of the detection system.

[0086] When the detection system detects that the fraction below 230°C in the bottom component of vacuum tower 12 is less than 10 wt%, the aromatic content is less than 1 wt%, and the alkanes content is greater than 85 wt%, the control valves control the steam valve, the first valve, the second valve, and the third valve to achieve the following: the top of vacuum tower 12 is connected to a first-stage hydrogenation vacuum system 13; the first-stage hydrogenated light component at the top of vacuum tower 12 enters the vacuum pump 16; the oil phase separated by the vacuum oil-water separator 18 enters the circulating side stream; part of the first-stage hydrogenated refined oil 21 is recycled back to step S1 as a diluent, and the other part is used as raw material for second-stage hydrogenation treatment to obtain second-stage hydrogenated material;

[0087] In other cases, the control valves control the steam valve, the first valve, the second valve, and the fourth valve to achieve the following: the top of the vacuum tower 12 is connected to the external discharge side line, or the top of the vacuum tower 12 is connected to a section of the hydrogenation vacuum system 13, a section of the hydrogenated light component at the top of the vacuum tower 12 enters the vacuum pump 16, and the oil phase separated by the vacuum oil-water separator 18 enters the external discharge side line; the entire section of hydrogenated refined oil is recycled back to step S1 as a diluent.

[0088] During vacuuming, steam 15 enters the nozzle (i.e., Laval nozzle throat diameter) in the vacuum pump 16 and is ejected at high speed to generate low pressure, drawing light components from the vacuum tower 12 into the vacuum system 13. The heavy components separated by the water cooler 14 enter the vacuum oil-water separator 18. Steam 15 passes through the vacuum pump 16 and is then cooled before entering the vacuum oil-water separator 18. The vacuum oil-water separator 18 separates exhaust gas 17, oil phase (new waste oil 19 or vacuum oil 39), and wastewater 20. Exhaust gas 17 and wastewater 20 are discharged. When the oil phase is new waste oil 19, it enters the discharge side line of the vacuum oil-water separator 18 and is discharged. When the oil phase is vacuum oil 39, it enters the circulation side line of the vacuum oil-water separator 18 and is circulated back to the hydrogenation unit 37.

[0089] The flow rate of steam 15 in vacuum pump 16 is 1 to 1.5 t / h, the vacuum degree of the first-stage hydrogenation vacuum system 13 is -0.08 MPa to 0 MPa, the vacuum tower 12 and the vacuum system 13 are under negative pressure, the light components in the vacuum tower 12 are drawn into the vacuum system and separated in the vacuum oil-water separator 18.

[0090] In order to separate the petroleum-based jet fuel contained in the diluent from the system, an external discharge side line is added to the oil phase outlet of the vacuum oil-water separator 18 for discharging light sludge oil 39. After the petroleum-based jet fuel is separated cleanly (meeting the system separation standard), the vacuum oil 19 is circulated back to the first-stage hydrogenation unit 37 through the circulation side line.

[0091] The system separation standard is as follows: in the first stage of hydrorefined oil, the fraction below 230℃ is less than 10wt%, the aromatic content is less than 1wt%, and the alkanes content is greater than 85wt%. The lower the fraction below 230℃ and the higher the alkanes content, the better the separation effect is considered.

[0092] The two-stage hydrodistillation system 36 includes a two-stage hydrodistillation column 29, a bottom reboiler 30 of which is provided at the bottom of the column, and a biofuel side-stream column 34 is provided at the top of the column.

[0093] See Figure 1 As shown, the present invention provides a method for producing bio-jet fuel, using the above-described apparatus for producing bio-jet fuel, comprising the following steps:

[0094] S1. Oily raw materials and petroleum-based jet fuel (a diluent) are mixed evenly to obtain a mixture;

[0095] S2. The mixture obtained in step S1 and hydrogen are fed into a first-stage hydrogenation reactor 5 in the presence of a hydrogenation catalyst to obtain a first-stage hydrogenated material.

[0096] S3. The hydrogenated material obtained in step S2 enters the first high-pressure separator 9 for the first high-pressure separation to obtain gas 11, a first oil phase material and water 8. The gas and water obtained from the first high-pressure separation are discharged. The first oil phase material passes through the stripping tower 10 and the vacuum tower 12 for the first separation to obtain a first hydrotreated refined oil 21 and a first hydrotreated light component.

[0097] S4. The detection system detects the composition of the hydrotreated oil in one stage and performs the following operations:

[0098] Operation 1: When the test results show that the fraction below 230℃ in the first-stage hydrorefined oil is less than 10wt%, the aromatic content is less than 1wt%, and the alkane content is greater than 85wt%, the control valve controls the steam valve to allow the first-stage hydrorefined light component to enter the first-stage hydrorefined vacuum system 13 for third separation to obtain external exhaust gas 17, vacuum oil 19, and water 20. Both gas 17 and water 20 obtained from the third separation are discharged. The control valve controls the third valve to allow the vacuum oil 19 to be recycled back to step S1 through the circulation side line as raw material for the production of bio-jet fuel. The control valve controls the first and second valves to allow part of the first-stage hydrorefined oil 21 to be recycled back to step S1 as a diluent, and the other part to be used as raw material for second-stage hydrorefining to obtain second-stage hydrorefined material.

[0099] Operation 2: In other cases, the control valve controls the first and second valves to recycle all of the hydrotreated oil 21 back to step S1 as a diluent; the control valve controls the steam valve to allow the light components of the hydrotreated oil to enter the first hydrotreated vacuum system 13 for the second separation to obtain exhaust gas 17, light sludge oil 39 and water 20; the control valve controls the fourth valve to allow the light sludge oil 39 to enter the exhaust side line for discharge, and the exhaust gas 17 and water 20 obtained from the second separation are also discharged.

[0100] S5. The second-stage hydrogenated material undergoes second high-pressure separation in the second high-pressure separator 26 to obtain gas (i.e., circulating hydrogen 27) and second-stage oil phase material. The circulating hydrogen 27 is recycled, and the second-stage oil phase material undergoes hydrodistillation separation in the second-stage hydrodistillation system 36 to obtain biojet fuel and biodiesel.

[0101] Figure 2 The apparatus and flow diagram for the SRJET process of producing bio-jet kerosene. See also... Figure 2 As shown, the SRJET process for producing bio-jet fuel employs a two-stage hydrogenation process:

[0102] a) The first-stage hydrogenation process for oil and fat feedstocks corresponds to the first-stage hydrogenation unit 37, used to remove oxygen and other heteroatoms from the feedstock to obtain hydrogenated refined oil. The main process includes: waste cooking oil feedstock 1 is mixed with circulating diluent 21 and enters the feedstock buffer tank 2. The resulting mixture is then mixed with compressed hydrogen gas 3 (compressed from fresh hydrogen 6 by the fresh hydrogen compressor 7 in the first-stage hydrogenation unit), heated by the first-stage hydrogenation heater 4, and then enters the first-stage hydrogenation reactor 5 for deoxygenation. The deoxygenation reaction products are then sent to the high-pressure separator 9 for three-phase separation, with water 8 and waste hydrogen 11 separated separately. The oil phase, discharged from the bottom and top of the high-pressure separator 9, enters the stripping tower 10 (with 1.0 MPa steam 15 input) to remove hydrogen sulfide and light components. It then enters the vacuum tower 12 to initially remove hydrogen sulfide and water. The top and bottom of the vacuum tower 12 respectively yield a first-stage hydrotreated light component and a first-stage hydrotreated refined oil 21. The first-stage hydrotreated light component enters the first-stage hydrotreated vacuum system 13 for further removal of hydrogen sulfide and water. Part of the first-stage hydrotreated refined oil 21 is recycled back to the raw material buffer tank 2 as a circulating diluent, and the other part enters the raw material buffer tank 22 of the second-stage hydrotreated unit.

[0103] In this process, the light components in the vacuum tower 12 enter the first stage of the hydrogenation vacuum system 13, and then enter the water cooler 14. After cooling, condensate and some uncondensed light components are obtained. 1.0 MPa steam 15 enters the vacuum pump 16 to obtain low-pressure steam. The condensed steam, condensate and uncondensed gas enter the vacuum oil-water separator 18 to separate and obtain external exhaust gas 17, vacuum oil 19 and wastewater 20. Vacuum oil 19 can be recycled back to the raw material buffer tank 2, and wastewater 20 is sent to the downstream unit for treatment.

[0104] b) The second-stage hydrotreating unit 38 corresponds to the hydrotreating conversion of hydrotreated oil. It is used to adjust the distillation range distribution of the product and lower the freezing point. Then, the product is separated to obtain bio-jet fuel that meets the quality requirements. The main process includes: another part of the first-stage hydrotreated oil 21 enters the feed buffer tank 22 of the second-stage hydrotreating unit 38 and is mixed with compressed circulating hydrogen (circulating hydrogen 27 is compressed by the second-stage hydrotreating circulating hydrogen compressor 28). After being heated by the second-stage hydrotreating heater 23, it enters the hydrocracking isomerization reactor 24 and then enters the post-hydrotreating refining reactor 25. The post-hydrotreating refining product oil enters the high-pressure separator 26 for gas-liquid two-phase separation. The gas is discharged from the top of the high-pressure separator 26 as circulating hydrogen 27, and the liquid phase enters the second-stage hydrotreating fractionation system 36 for separation.

[0105] The liquid phase enters the two-stage hydrodistillation system 36 and first enters the two-stage hydrodistillation column 29. The side stream material of the two-stage hydrodistillation column 29 enters the bio-jet fuel side stream column 34. The bio-jet fuel side stream column 34 separates bio-jet fuel product 35 at the bottom of the column. The material separated at the top of the bio-jet fuel side stream column 34 is recycled back to the two-stage hydrodistillation column 29. The material obtained at the bottom of the two-stage hydrodistillation column 29 is divided into two parts. One part enters the two-stage hydrodistillation column bottom reboiler 30 through the two-stage hydrodistillation column bottom circulation pump 31, and after reboiling, it is recycled back to the two-stage hydrodistillation column 29. The other part is discharged as biodiesel 33 through the biodiesel pump 32.

[0106] The waste cooking oil feedstock 1 has a high oxygen content (approximately 12% by mass). The first-stage hydrodeoxygenation process (first-stage hydrorefining reactor 5) releases a large amount of heat. To ensure the safe and stable operation of the waste cooking oil hydrorefining process and protect the catalyst and reactor, a large amount of petroleum-based jet fuel is required as a circulating diluent during the initial startup phase (circulating diluent: waste cooking oil ≥ 1:5). After a period of operation, the resulting first-stage hydrorefined oil 21 is used as the circulating diluent for the first-stage hydrorefining reaction system. To produce a standard-compliant pure bio-jet fuel product (pure HEFA-SPK) and ensure that the bio-jet fuel product complies with the quality assurance system, the petroleum-based jet fuel added during startup must be separated from the above-mentioned unit. When the fraction below 230℃ in the first-stage hydrorefined oil 21 is less than 10 wt%, the aromatic content is less than 1 wt%, and the alkanes content is greater than 85 wt%, it is considered that the petroleum-based jet fuel has been completely separated from the above-mentioned unit.

[0107] In the SRJET process for producing bio-jet fuel, the first-stage hydrorefined oil 21, which is mixed with petroleum-based jet fuel, enters the second-stage hydrorefining unit 38. Taking advantage of the different properties of petroleum-based jet fuel and hydrorefined oil from waste catering (see Table 1), they are separated in the distillation column 29 of the second-stage hydrorefining unit. The separated petroleum-based jet fuel is discharged from the distillation column side stream 34 to ensure that the petroleum-based jet fuel is completely separated in order to produce pure bio-jet fuel product (pure HEFA-SPK).

[0108] The drawback of using the two-stage hydrogenation unit distillation column 38 for the separation of petroleum-based jet fuel is that the bottom temperature of the two-stage hydrogenation unit distillation column 29 is high (approximately 330°C) during separation. Furthermore, due to the smaller distillation range but higher density of petroleum-based jet fuel compared to single-stage hydrogenated refined oil obtained from restaurant waste oil (as shown in Table 1), the two-stage hydrogenation unit distillation column 29 is particularly prone to "sudden boiling" during high-temperature separation (similar to the separation of oil and water in daily life). This "sudden boiling" causes the liquid level in the distillation column to fluctuate wildly between 0% and 100% (e.g.,...). Figure 4As shown, the drastic fluctuations in the liquid level of the distillation column make it extremely easy for the bottom pumps of the distillation column (the bottom circulation pump 31 of the second-stage hydrodistillation column and the biodiesel pump 32) to be evacuated, the flow rate of the bottom reboiler 30 of the second-stage hydrodistillation column fluctuates drastically, and there is a risk of dry burning of the furnace tubes.

[0109] Furthermore, the separation time for the first-stage hydrorefined oil obtained by separating petroleum-based jet fuel and restaurant waste oil using the two-stage hydrorefining unit distillation column 29 is relatively long, consumes a large amount of bio-based restaurant waste oil raw material, and has a relatively high procurement cost for restaurant waste oil, resulting in waste of bio-based raw materials. Moreover, the energy consumption for separating petroleum-based jet fuel and restaurant waste oil using the distillation column is even higher.

[0110] Table 1. Comparison of properties of hydrorefined oils from petroleum-based jet fuel and waste cooking oil.

[0111]

[0112]

[0113] Example 1

[0114] See Figure 1 As shown, this embodiment provides an apparatus and method for producing bio-jet fuel, including the following steps:

[0115] S1. Waste cooking oil 1 and petroleum-based jet fuel (a diluent) are mixed evenly in a hydrogenation feed buffer tank 2 to obtain a mixture; the mass ratio of waste cooking oil 1 to diluent is 1:5.

[0116] S2. The mixture obtained in step S1 is mixed with compressed hydrogen 3 (obtained by compressing fresh hydrogen 6 through a first-stage hydrogenation unit compressor 7), heated in a first-stage hydrogenation heater 4, and then fed into a first-stage hydrogenation reactor 5 (hydrogen partial pressure 6.5 MPa, reaction temperature 290 °C, volume hourly space velocity 0.28 h⁻¹). -1 The hydrogen-to-oil volume ratio is 1200, and a hydrogenation process is carried out in the presence of a hydrogenation catalyst (RJW-3) to obtain a hydrogenated feedstock.

[0117] S3. The hydrogenated material obtained in step S2 enters the first high-pressure separator 9 for the first high-pressure separation (separation conditions: pressure 6.1MPa, temperature 45℃) to obtain water 8, waste hydrogen 11 and a first-stage oil phase material. Water 8 and waste hydrogen 11 are discharged from the bottom and top of the first-stage high-pressure separator 9, respectively. The first-stage oil phase material enters the stripping tower 10 (input 1.0MPa steam 15) to remove hydrogen sulfide, and then enters the vacuum tower 12 to initially remove hydrogen sulfide, water (partially carried in the stripping tower 10) and light components (separation conditions: -0.064MPa, temperature: 167℃). The top and bottom of the vacuum tower 12 respectively yield a first-stage hydrogenated light component and a first-stage hydrogenated refined oil 21.

[0118] S4. The detection system detects the composition of the first-stage hydrorefined oil 21. Initially, due to the presence of petroleum-based jet fuel in the reaction system, the composition of the first-stage hydrorefined oil does not meet the following requirements: fractions below 230℃ are less than 10wt%, aromatic content is less than 1wt%, and alkane content is greater than 85wt%. At this point, the control valves control each valve to achieve the following: Steam 15 (flow rate of 1.5t / h) enters the nozzle (i.e., Laval nozzle throat diameter) in the vacuum pump 16, and is ejected at high speed to generate low pressure. The control valves control the steam valve to draw all the first-stage hydrorefined light components from the top of the vacuum tower 12 into the vacuum system 13 (vacuum degree -0.07MPa). The water-cooled heavy components and water-cooled light components are cooled and separated by the water cooler 14. The water-cooled heavy components directly enter the vacuum oil-water separator 18, while the water-cooled light components are drawn into the vacuum pump 16 and, together with the steam 15, are cooled and then enter the vacuum oil-water separator 18 (separation conditions: hydrogen partial pressure 6.5MPa, reaction temperature 290℃, volume hourly space velocity 0.28h). -1 The hydrogen-to-oil volume ratio is 1200. After being separated by the vacuum oil-water separator 18, external exhaust gas 17, new sludge oil 39 and sewage 20 are obtained. External exhaust gas 17, new sludge oil 39 (by controlling the fourth valve to make all the new sludge oil 39 enter the external discharge side line of the vacuum oil-water separator 18) and sewage 20 are all discharged.

[0119] Continuous monitoring of the first-stage hydrorefined oil continues until the fraction below 230°C is less than 10 wt%, the aromatic content is less than 1 wt%, and the alkane content is greater than 85 wt%. At this point, the control valves are adjusted to achieve the following: the first-stage hydrorefined light components are separated by a vacuum oil-water separator 18 (separation conditions: hydrogen partial pressure 6.5 MPa, reaction temperature 290°C, volumetric hourly space velocity 0.28 h⁻¹). -1 The oil phase obtained from the separation of hydrogen-oil volume ratio (1200) is changed from fresh waste oil 39 to vacuum oil 19. That is, the light components of the first-stage hydrotreating are separated by the vacuum oil-water separator 18 to obtain exhaust gas 17, vacuum oil 19 and wastewater 20. Exhaust gas 17 and wastewater 20 are completely discharged. Vacuum oil 19 is recycled back to the first-stage hydrotreating feedstock buffer tank 2 as a feedstock for the production of bio-jet fuel. Based on the first-stage hydrorefined oil, 88 wt% of the first-stage hydrorefined oil is recycled back to the first-stage hydrotreating feedstock buffer tank as a diluent. Tank 2: 12 wt% of the first-stage hydrorefined oil is fed into the second-stage hydrorefining unit feedstock buffer tank 22 of the second-stage hydrorefining unit 38. It is then mixed with compressed circulating hydrogen (circulating hydrogen 27 is compressed by the second-stage hydrorefining circulating hydrogen compressor 28), heated by the second-stage hydrorefining heater 23, and then enters the hydrocracking isomerization reactor 24 (filled with hydrocracking isomerization catalyst, RIW-2). Finally, it enters the post-hydrorefining reactor 25 (filled with post-hydrorefining catalyst, RLF-10). FThe resulting post-hydrogenated refined oil enters the second high-pressure separator 26 (separation conditions: pressure 6.1MPa, temperature 45℃) for gas-liquid two-phase separation. The gas is discharged from the top of the high-pressure separator 26 as circulating hydrogen 27, and the liquid phase enters the two-stage hydrofraction system 36 for separation.

[0120] In step S4, the composition of the first hydrorefined oil is shown in Table 2.

[0121] In this process, after the liquid phase enters the two-stage hydrodistillation system 36, it first enters the two-stage hydrodistillation column 29. The side stream material of the two-stage hydrodistillation column 29 enters the bio-jet fuel side stream column 34. The bio-jet fuel side stream column 34 separates bio-jet fuel product 35 at the bottom of the column. The material separated at the top of the bio-jet fuel side stream column 34 is recycled back to the two-stage hydrodistillation column 29. The material obtained at the bottom of the two-stage hydrodistillation column 29 is divided into two parts. One part (110 t / h) enters the two-stage hydrodistillation column bottom reboiler 30 through the two-stage hydrodistillation column bottom circulation pump 31. After reboiling, it is recycled back to the two-stage hydrodistillation column 29 to provide a heat source for the distillation column. The other part (1.5 t / h) is recycled back to the first-stage hydrodistillation unit. Alternatively, in other embodiments, the other part (1.5 t / h) can also be discharged as biodiesel 33 through the biodiesel pump 32.

[0122] In this embodiment, when the 100,000-ton / year bio-jet fuel plant starts up, the first-stage hydrogenation unit vacuum system is used to separate petroleum-based jet fuel and hydrorefined waste oil from catering waste. The separation time for petroleum-based jet fuel and hydrorefined waste oil is 37 hours. At the time of separation, approximately 295 tons of catering waste oil replaces the system's padding material. When using the first-stage hydrogenation unit vacuum system to separate petroleum-based jet fuel and hydrorefined waste oil from catering waste, the vacuum system temperature is low and the liquid level is stable (e.g., Figure 3 As shown in the figure, it can achieve higher separation accuracy than distillation columns.

[0123] This embodiment utilizes a single-stage hydrogenation unit vacuum system 13 to separate petroleum-based jet fuel and hydrorefined oil from waste catering oil. It also adds a vacuum oil-water separator 18 to facilitate the discharge of petroleum-based jet fuel, specifically a light waste oil discharge process, thereby achieving efficient, stable, and rapid separation of petroleum-based jet fuel and hydrorefined oil from waste catering oil. The vacuum system achieves the triple objectives of dehydration, hydrogen sulfide removal, and the separation of petroleum-based jet fuel and hydrorefined oil from waste catering oil.

[0124] This invention utilizes a single-stage hydrogenation unit vacuum system to separate the initially added petroleum-based jet fuel. The entire separation process is stable, with a low inlet temperature (approximately 180°C) in the vacuum system. No distillation column is required for separation, and there is no "sudden boiling" phenomenon during the separation process. Compared to distillation column separation, the operating conditions are more stable, and system fluctuations are smaller (e.g., ...). Figure 3As shown in the figure, the separation time for petroleum-based jet fuel using the vacuum system is relatively short, and the entire separation process is safe, stable, and efficient. Moreover, higher precision separation can be achieved (the two-stage hydrodistillation tower can achieve a fraction of less than 230°C with less than 10 wt% aromatics and more than 85 wt% alkanes in the refined oil, while the one-stage hydrodistillation vacuum system can achieve a fraction of less than 250°C with less than 3 wt% aromatics and more than 90 wt% alkanes in the refined oil).

[0125] Comparative Example 1

[0126] See Figure 2 As shown, this comparative example provides an apparatus and method for producing bio-jet fuel, which differs from the embodiments in that:

[0127] S3. The hydrogenated material obtained in step S2 enters the first high-pressure separator 9 for the first high-pressure separation. Water 8 and waste hydrogen 11 are discharged from the bottom and top of the first high-pressure separator 9, respectively. The oil phase material enters the stripping tower 10 (input 1.0MPa steam 15) to remove hydrogen sulfide, and then enters the vacuum tower 12 to initially remove hydrogen sulfide, water (partially carried in the stripping tower 10) and light components. The top and bottom of the vacuum tower 12 respectively yield the first hydrogenated light components and the first hydrogenated refined oil 21. A portion (88wt%) of the first hydrogenated refined oil 21 is recycled back to step S1 as a diluent, and the other portion (12wt%) is used as raw material for the second hydrogenation treatment to obtain the second hydrogenated material. The first hydrogenated light components enter the first hydrogenation vacuum system 13.

[0128] Steam 15 enters the nozzle (i.e., Laval nozzle throat diameter) in the vacuum pump 16, and is ejected at high speed to generate low pressure, drawing a section of hydrogenated light components from the top of the vacuum tower 12 into the vacuum system 13 (the flow rate of steam 15 in the vacuum pump 16 is 1.5 t / h, and the vacuum degree of the section of the hydrogenated vacuum system 13 is -0.07 MPa). The water-cooled heavy components and water-cooled light components are cooled and separated by the water cooler 14. The water-cooled heavy components directly enter the vacuum oil-water separator 18, while the water-cooled light components are drawn into the vacuum pump 16 and cooled together with steam 15 before entering the vacuum oil-water separator 18. The vacuum oil-water separator 18 separates the exhaust gas 17, vacuum oil 19, and wastewater 20. The exhaust gas 17 and wastewater 20 are all discharged, and the wastewater 20 is sent to the downstream unit for treatment; the vacuum oil 19 is recycled back to the raw material buffer tank 2.

[0129] S4. Another portion of the first-stage hydrorefined oil 21 enters the second-stage hydrorefining unit feedstock buffer tank 22 of the second-stage hydrorefining unit 38, where it is mixed with compressed circulating hydrogen (circulating hydrogen 27 is compressed by the second-stage hydrorefining circulating hydrogen compressor 28), heated by the second-stage hydrorefining heater 23, and then enters the hydrocracking isomerization reactor 24, and then enters the post-hydrorefining reactor 25. The post-hydrorefined product oil obtained enters the second high-pressure separator 26 for gas-liquid two-phase separation. The gas phase is discharged from the top of the high-pressure separator 26 as circulating hydrogen 27, and the liquid phase enters the second-stage hydrorefining fractionation system 36 for separation.

[0130] In this process, after the liquid phase enters the two-stage hydrofraction system 36, the petroleum-based jet fuel is separated from the reaction system through the bio-jet fuel side-line tower 34 of the two-stage hydrofraction tower 29, taking advantage of the difference in properties between petroleum-based jet fuel and hydrorefined oil from catering waste oil (see Table 1). When the fraction below 230℃ in the first-stage hydrorefined oil is less than 10wt%, the aromatic content is less than 1wt%, and the alkanes content is greater than 85wt%, the separation of petroleum-based jet fuel in the reaction system is considered complete.

[0131] After separation, the composition of hydrorefined oil 21 is shown in Table 3.

[0132] Subsequently, the liquid phase from the high-pressure separator 26 enters the second-stage hydrodistillation column 29, and the side stream material from the second-stage hydrodistillation column 29 enters the bio-jet fuel side stream column 34. The bio-jet fuel side stream column 34 separates bio-jet fuel product 35 at the bottom of the column, and the material separated at the top of the bio-jet fuel side stream column 34 is recycled back to the second-stage hydrodistillation column 29. The material obtained at the bottom of the second-stage hydrodistillation column 29 is divided into two parts. One part (110 t / h) enters the reboiler 30 at the bottom of the second-stage hydrodistillation column through the bottom circulation pump 31 and is recycled back to the second-stage hydrodistillation column 29 after reboiling. The other part (1.5 t / h) is recycled back to the first-stage hydrodistillation unit.

[0133] In this comparative example, after the 100,000-ton / year bio-jet fuel plant starts up, the two-stage hydrogenation unit's distillation column separates petroleum-based jet fuel and hydrorefined waste oil from catering waste. The separation time is approximately 69.5 hours, and approximately 380 tons of catering waste oil replace the padding material upon completion. During the separation of petroleum-based jet fuel and hydrorefined waste oil, the liquid level in the distillation column fluctuates significantly between 0% and 100% (e.g., ...). Figure 4 As shown in the figure, large fluctuations in the liquid level of the distillation column cause uneven liquid distribution in the reboiler tubes at the bottom of the distillation column, posing a risk of dry burning of the tubes. This separation method has large operational fluctuations, unstable operating conditions, and high risks.

[0134] Table 2

[0135]

[0136] Table 3

[0137]

[0138] As shown in Tables 2 and 3, the vacuum system of Example 1 can achieve a higher separation standard for separating petroleum-based jet fuel and refined oil. Specifically, the separation of petroleum-based jet fuel is more thorough (the two-stage hydrodistillation tower can achieve a fraction of less than 10% at temperatures below 230°C, an aromatic content of less than 1%, and a alkane content of more than 85% in the refined oil; the one-stage hydrodistillation vacuum system can achieve a fraction of less than 3% at temperatures below 250°C, an aromatic content of less than 1%, and a alkane content of more than 90% in the refined oil).

[0139] Furthermore, compared with Comparative Example 1, Example 1 saves approximately 85 tons of waste cooking oil and 32.5 hours of time (Example 1 requires 37 hours, while Comparative Example 1 requires 69.5 hours).

[0140] It should be noted that the embodiments described above are only for explaining the present invention and do not constitute any limitation on the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory terms, not limiting terms. Modifications can be made to the present invention within the scope of the claims, and revisions can be made to the present invention without departing from the scope and spirit of the present invention. Although the present invention described herein relates to specific methods, materials, and embodiments, it does not mean that the present invention is limited to the specific examples disclosed herein; on the contrary, the present invention can be extended to all other methods and applications with the same function.

Claims

1. A method for producing bio-jet fuel, characterized in that, Includes the following steps: S1. Oily raw materials and petroleum-based jet fuel (a diluent) are mixed evenly to obtain a mixture; S2. The mixture obtained in step S1 and hydrogen are subjected to a hydrogenation process in the presence of a hydrogenation catalyst to obtain a hydrogenated material. S3. The hydrogenated material obtained in step S2 is subjected to a first high-pressure separation to obtain gas, a first oil phase material and water. The first oil phase material is further separated to obtain a first hydrotreated refined oil and a first hydrotreated light component. S4. Analyze the composition of a section of hydrotreated oil and perform the following operations: Operation 1: In the case that the fraction below 230℃ in the first-stage hydrorefined oil is less than 10wt%, the aromatic content is less than 1wt%, and the alkane content is greater than 85wt%, the first-stage hydrorefined light component is separated into gas, vacuum oil, and water in the third stage. The vacuum oil is recycled back to step S1 as a raw material for the production of bio-jet fuel. Part of the first-stage hydrorefined oil is recycled back to step S1 as a diluent, and the other part is used as a raw material for second-stage hydrorefining to obtain second-stage hydrorefined material. Operation 2: In all other cases, the entire hydrorefined oil from one stage is recycled back to step S1 as a diluent. S5. The second-stage hydrogenated material undergoes a second high-pressure separation to obtain gas and a second-stage oil phase material. The second-stage oil phase material is then separated by hydrodistillation to obtain biojet fuel and biodiesel. In step S4, the third separation is performed by vacuuming.

2. The method according to claim 1, characterized in that, The oily raw materials include one or more of animal fats, vegetable oils, and waste cooking oil; and / or In step S1, the mass ratio of the oily raw material to the diluent is less than or equal to 1:5, preferably 1:100 to 1:

5.

3. The method according to claim 1 or 2, characterized in that, In step S3, the conditions for the first high-pressure separation include: pressure 6.0–7.2 MPa, temperature 20–55 °C; and / or In step S3, the gas and water obtained from the first high-pressure separation are discharged; and / or In step S3, the conditions for the first separation include: pressure -0.08 to 0 MPa; and / or In step S4, in operation one, based on the first-stage hydrorefined oil, 85wt%–90wt% of the first-stage hydrorefined oil is recycled back to step S1 as a diluent, and 10wt%–15wt% is used as raw material for second-stage hydrorefining to obtain the second-stage hydrorefined material; and / or In step S4, during operation one, both the gas and water obtained from the third separation are discharged; and / or In step S4, during operation two, the first-stage hydrogenated light component is discharged, or the first-stage hydrogenated light component undergoes a second separation to obtain gas, light sludge oil, and water, all of which are discharged. Preferably, the second separation is performed by vacuuming; and / or In step S5, the conditions for the second high-pressure separation include a pressure of 6.0–7.2 MPa and a temperature of 20–55°C; and / or In step S5, the gas obtained from the second high-pressure separation is recycled as circulating hydrogen.

4. The method according to any one of claims 1-3, characterized in that, The hydrotreating catalyst comprises a metal active component and a support. The support is selected from one or more of alumina, silicon oxide, zirconium oxide, and titanium oxide. The metal active component is at least one metal element selected from Group VIB and at least one metal element selected from Group VIII. The Group VIB metal element is molybdenum and tungsten, and the Group VIII metal element is cobalt and nickel. Based on the total weight of the hydrotreating catalyst, the content of the metal active component, calculated as oxides, is 5-50% by weight. Preferably, based on the total weight of the hydrotreating catalyst, the content of the Group VIB metal element, calculated as oxide, is 4-40% by weight, and the content of the Group VIII metal element is 1-10% by weight; more preferably, the active metal component contains cobalt and molybdenum. Based on the total weight of the hydrotreating catalyst, the content of the Group VIB metal element, calculated as oxide, is 8-35% by weight, and the content of the Group VIII metal element is 2-5% by weight.

5. The method according to any one of claims 1-4, characterized in that, The reaction conditions for the first-stage hydrogenation treatment include: hydrogen partial pressure 6.0–7.2 MPa, reaction temperature 280–320 °C, and volume hourly space velocity (VHSV) 0.21–0.38 h⁻¹. -1 Hydrogen-to-oil volume ratio 1000–1500; The preferred reaction conditions for the first-stage hydrogenation treatment are: reaction temperature 290–300°C.

6. The method according to any one of claims 3-5, characterized in that, The reaction conditions for the second separation include: hydrogen partial pressure of 6.0–7.2 MPa, reaction temperature of 280–320 °C, and volume hourly space velocity of 0.21–0.38 h⁻¹. -1 Hydrogen-to-oil volume ratio of 1000–1500; and / or The reaction conditions for the third separation include: hydrogen partial pressure 6.0–7.2 MPa, reaction temperature 280–320 °C, and volume hourly space velocity 0.21–0.38 h⁻¹. -1 The hydrogen-to-oil volume ratio is 1000–1500.

7. The method according to any one of claims 1-6, characterized in that, The two-stage hydrotreating process includes hydrocracking isomerization and post-hydrorefining. Preferably, the hydrocracking isomerization treatment uses a hydrocracking isomerization catalyst, which contains a support and an active metal component supported on the support. The support of the hydrocracking isomerization catalyst contains alumina and silica-alumina. Based on the support, the alumina content is 20-80% by weight, the silica-alumina content is 80-20% by weight, and the active metal component includes platinum and palladium. Based on the total weight of the hydrocracking catalyst, the active metal component content, calculated as oxides, is 0.1-5% by weight. Preferably, the conditions for the hydrocracking isomerization treatment include: hydrogen partial pressure of 6.0–7.2 MPa, reaction temperature of 310–340 °C, and volume hourly space velocity of 0.48–0.88 h⁻¹. -1 Hydrogen-to-oil volume ratio 500-700; Preferably, the specific surface area of ​​the hydrocracking isomerization catalyst is greater than or equal to 180 m². 2 / g, pore volume greater than or equal to 0.3ml / g, bulk density 0.58~0.62g / cm³ 3 Equivalent diameter 1.0~1.2mm.

8. The method according to claim 7, characterized in that, The post-hydrogenation refining process uses a post-hydrogenation refining catalyst. Preferably, the post-hydrorefining catalyst contains a support and an active metal component supported on the support. The support of the post-hydrorefining catalyst contains alumina and silica-alumina. Based on the support, the alumina content is 40-60% by weight, the silica-alumina content is 60-40% by weight, and the active metal component includes platinum and palladium. Based on the total weight of the post-hydrorefining catalyst, the active metal component content, calculated as oxides, is 0.1-5% by weight; and / or Preferably, the specific surface area of ​​the post-hydrogenation refining catalyst is greater than or equal to 250 m². 2 / g, pore volume greater than or equal to 0.4ml / g, bulk density 0.52~0.56g / cm³ 3 Equivalent diameter 1.2–1.4 mm; and / or The reaction conditions for the post-hydrogenation refining process include: a reaction temperature of 170–210 °C and a volume hourly space velocity of 0.6–1.1 h⁻¹. -1 The hydrogen-to-oil volume ratio is 500–700, the circulating hydrogen purity is 80–95% (V / V), and the hydrogen partial pressure is 6.0–7.2 MPa.

9. An apparatus for producing bio-jet fuel, characterized in that, It includes a first-stage hydrogenation unit and a second-stage hydrogenation unit connected in sequence. A hydrogenation unit comprises a hydrogenation reactor, a high-pressure separator, a stripping tower, and a vacuum tower connected in sequence, wherein the hydrogenation reactor is filled with a hydrogenation catalyst. The two-stage hydrogenation unit includes a hydrocracking isomerization reactor, a post-hydrorefining reactor, a second high-pressure separator, and a two-stage hydrofractionation system connected in sequence; the hydrocracking isomerization reactor and the post-hydrorefining reactor are respectively filled with hydrocracking isomerization catalyst and post-hydrorefining catalyst. The apparatus for producing bio-jet kerosene further includes a detection system, control valves, and a first-stage hydrogenation vacuum system. The first-stage hydrogenation vacuum system comprises a cooler, a vacuum pump, and a vacuum oil-water separator connected in sequence. The cooler is also connected to the vacuum oil-water separator. The vacuum oil-water separator has a circulation side line in its middle section, which is connected to the first-stage hydrogenation unit. A steam valve is installed at the top of the vacuum pump to control the amount of steam entering the vacuum pump. A first valve and a second valve are installed at the bottom of the vacuum tower, and a third valve is installed on the circulation side line. The detection system is used to detect the composition of the components at the bottom of the vacuum tower, and the control valves are used to control the steam valve, the first valve, the second valve, and the third valve based on the detection results of the detection system.

10. The apparatus according to claim 9, characterized in that, The two-stage hydrofraction system includes a two-stage hydrodistillation column, with a bottom reboiler at the bottom of the column and a biofuel side-stream column at the top; and / or The vacuum oil-water separator is further provided with an external discharge line in the middle, and a fourth valve is provided on the external discharge line. The control valve is used to control the fourth valve according to the detection result of the detection system; and / or The top of the vacuum tower is equipped with an external exhaust side line.

Images