PREPARATION METHOD AND SYSTEM OF LOW-CARBON JET BIOFUEL BASED ON WHOLE LIFE CYCLE

Abstract

Disclosed are a preparation method and a system of low-carbon jet biofuel based on whole life cycle. A low-carbon method and a system of using whole life cycle involving whole process from raw material acquisition, fuel preparation to fuel application are related. A prepared jet biofuel can be used in six types of aircrafts and engines thereof. Aircrafts using the jet biofuel can have a portion of greenhouse gas emission reduction of 50% to 80%.

Claims

1. A method for preparing low-carbon jet biofuel based on whole life cycle, the method comprising steps of: S1, screening and obtaining microalgae coupling with carbon spectrum characteristics of jet fuels; S2, cultivating the microalgae to obtain oleaginous microalgae, which have a strong carbon dioxide fixing ability and a high productivity of fatty acids; S3, extracting lipid from the oleaginous microalgae using a flash hydrothermal method to obtain biocrude containing lipid; S4, subjecting the biocrude to a heteroatom removing process and a hydrotreating process sequentially to obtain a hydrogenated product; and S5, subjecting the hydrogenated product to a fractionation process to obtain a kerosene component and a naphtha component, wherein the kerosene component is a jet biofuel.

2. The method according to claim 1, wherein the oleaginous microalgae have a carbon dioxide fixing ability in a range from 35 to 60 g/m.sup.2.Math.d.

3. The method according to claim 1, wherein the oleaginous microalgae have a yield of fatty acid in a range from 5 to 20 g/m.sup.2.Math.d.

4. The method according to claim 1, wherein the oleaginous microalgae have a lipid content in a range from 20% to 65%.

5. The method according to claim 1, wherein the oleaginous microalgae have a growth rate in a range from 20 to 30 g/m.sup.2.Math.d.

6. The method according to claim 1, wherein the step 4 comprises steps of: 4A, subjecting the biocrude to a heteroatom removing process in presence of a catalyst for removing heteroatoms to remove heteroatoms from an oil phase and obtain a heteroatom-removed product, and 4B, subjecting the heteroatom-removed product to a hydrotreating process in presence of a hydrogenation catalyst to obtain a hydrogenated product.

7. The method according to claim 6, wherein the catalyst for removing heteroatoms comprises one or more of Ni/Al.sub.2O.sub.3, Mo/Al.sub.2O.sub.3, Co/Al.sub.2O.sub.3, and No—Co/Al.sub.2O.sub.3.

8. The method according to claim 6, wherein the hydrogenation catalyst comprises one or more of Pt/C, Pt/γ—Al.sub.2O.sub.3, Pd/C, Ni—Mo/Al.sub.2O.sub.3, and Co—Mo/Al.sub.2O.sub.3.

9. The method according to claim 1, further comprising a step S6 of performing a hydroisomerisation and hydrocracking process on the kerosene component obtained in step S5.

10. Use of the jet biofuel prepared using the method according to claim 1.

11. A low-carbon jet biofuel system based on whole life cycle, comprising: a selection module, which is configured to screen and obtain microalgae coupling with carbon spectrum characteristics of jet fuels; a cultivation module, which is configured to cultivate the microalgae to obtain oleaginous microalgae having a strong carbon dioxide fixing ability and a high productivity of fatty acids; a raw material module, which is configured to extract lipid from the oleaginous microalgae to obtain biocrude containing lipid; a preparation module, which is configured to sequentially perform a heteroatom removing process, a hydrotreating process, and a fractionation process to the biocrude to obtain a jet biofuel; and an application module, which is configured to apply the jet biofuel to an aircraft engine.

12. The system according to claim 11, wherein the oleaginous microalgae have a carbon dioxide fixing ability in a range from 35 to 60 g/m.sup.2.Math.d.

13. The system according to claim 12, wherein the oleaginous microalgae have a yield of fatty acid in a range from 5 to 20 g/m.sup.2.Math.d.

14. The system according to claim 12, wherein the oleaginous microalgae have a lipid content in a range from 20% to 65%.

15. The system according to claim 12, wherein the oleaginous microalgae have a growth rate in a range from 20 to 30 g/m.sup.2.Math.d.

16. The system according to claim 11, wherein the preparation of the jet biofuel comprises steps of: (1) subjecting the biocrude to a heteroatom removing process in presence of a catalyst for removing heteroatoms to remove heteroatoms from an oil phase and obtain a heteroatom-removed product; (2) subjecting the heteroatom-removed product to a hydrotreating process in presence of a hydrogenation catalyst to obtain a hydrogenated product; and (3) subjecting the hydrogenated product to a fractionation process to obtain a kerosene component and a naphtha component, wherein the kerosene component is the jet biofuel; and (4) optionally, subjecting the kerosene component to a hydroisomerisation and hydrocracking process.

17. The system according to claim 16, wherein the catalyst for removing heteroatoms comprises one or more of Ni/Al.sub.2O.sub.3, Mo/Al.sub.2O.sub.3, Co/Al.sub.2O.sub.3, and No—Co/Al.sub.2O.sub.3.

18. The system according to claim 16, wherein the hydrogenation catalyst comprises one or more of Pt/C, Pt/γ—Al.sub.2O.sub.3, Pd/C, Ni—Mo/Al.sub.2O.sub.3, and Co—Mo/Al.sub.2O.sub.3.

19. The system according to claim 11, wherein the application module can be applied in at least one of a single aisle, a small twin aisle, a twin aisle, a large quad, a v, and a business jet.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0093] The accompanying drawings provide further understandings of the present disclosure and constitute one part of the description. The drawings are used for interpreting the present disclosure together with the embodiments, not for limiting the present disclosure. In the drawings:

[0094] FIG. 1 is a flowchart showing a method for preparing a low-carbon jet biofuel based on whole life cycle assessment according to the present disclosure.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0095] The technical solutions of the present disclosure will be further explained below with reference to the embodiments.

EXAMPLE 1

[0096] (1) Selection of Microalgae was as follows. Nannochloropsis algae with oil content in a range from 20% 40%, a growth rate in a range from 20 to 30 g/m.sup.2.Math.d, and carbon spectrums of C14, C16, and C18 were selected.

[0097] (2) Carbon dioxide (CO.sub.2) from a coal-fired power plant was purified or directly fed to a microalgae cultivation pond. An amount of CO.sub.2 was adjusted through control of pH value, and the pH value was controlled in a range from 5.5 to 7.8. In-situ harvest of the Nannochloropsis algae is realized through control of pH value. The pH value for in-situ harvest was either in a range from 4.0 to 4.8 under acidic conditions, or in a range from 9.5 to 10.5 under alkaline conditions. A concentration for in-situ harvest could be in a range from 20 to 30 g/L. After centrifugal dewatering, the concentration was in a range from 150 to 250 g/L. After filtering and disinfecting, water collected by harvest and dewatering was returned to the cultivation pond.

[0098] (3) Microalgae pulp was delivered into a hydrothermal reactor which had been heated to a preset temperature by means of a high-pressure pump. The temperature of the reactor was controlled in a range from 270° C. to 300° C. Nitrogen was fed to the reactor with a retention time in a range from 5 to 30 min to keep an inert atmosphere in the reactor. Since it takes time for cell wall rupture of the Nannochloropsis, the heating rate was less than 100° C./min. Materials from an outlet of the hydrothermal reactor were fed to a multiphase separator, which was provided with a filter therein. Gas was discharged from an upper part of the multiphase separator. Solid residues were precipitated at a bottom part of the multiphase separator and then discharged at the bottom part thereof. A liquid portion overflowed from the filter provided at the upper part of the multiphase separator, so that a liquid bio-oil and water were obtained. An oil phase and a water phase were separated to obtain a biocrude. After purification and disinfection, the water phase was returned to the cultivation pond to provide nitrogen sources.

[0099] (4) The biocrude was subjected to a heteroatom removal process and a hydrotreating process first. In a hydrogenation reactor, a catalyst for removing heteroatoms was provided at an upper layer, and a hydrogenation catalyst was provided at a lower layer. The catalyst for removing heteroatoms was Ni/Al.sub.2O.sub.3, a hydrogen partial pressure was in a range from 8 to 10 MPa, a hydrogen to oil ratio was in a range from 400 to 800 m.sup.3/m.sup.3, a temperature was in a range from 260° C. to 300° C., and a velocity of flow was in a range from 0.25 to 2 .sup.−1. The hydrogenation catalyst was Ni—Mo/Al.sub.2O.sub.3, a hydrogen partial pressure was in a range from 5 to 10 MPa, a hydrogen to oil ratio was in a range from 600 to 1000 m.sup.3/m.sup.3, a temperature was in a range from 280° C. to 400° C., and a superficial flow velocity was in a range from 0.25 to 2 h.sup.−1. After the heteroatom removing and the hydrotreating process, a hydrocarbon distillate could be obtained. Next, a fractionation process was performed. A light distillate carbon number distribution was in a range from C8 to C16, and a fractionation temperature distribution was in a range from 160° C. to 280° C. A high distillate carbon number distribution was in a range from C17 to C32, and a fractionation temperature distribution was in a range from 160° C. to 350° C. Besides, there was 15% to 15% of naphtha fuel having carbon number distribution less than C7.

[0100] (5) The high hydrocarbon distillate was hydrocracked to obtain a low distillate hydrocarbon fuel. The low distillate hydrocarbon fuel obtained by hydrocracking and a low-distillate hydrocarbon fuel obtained by hydrotreating were performed with a hydroisomerization process to obtain a jet fuel that met performance requirements. A hydrocracking catalyst was Ni—Mo/SiO.sub.2—Al.sub.2O.sub.3, a hydroisomerization catalyst was Pt/Al.sub.2O.sub.3—F, and a hydrogen partial pressure was in a range from 3 to 15 MPa. A hydrogen to oil ratio was in a range from 1000 to 1500 m.sup.3/m.sup.3, a temperature was in a range from 400° C. to 450° C., and a superficial flow velocity was in a range from 0.25 to 2 h.sup.−1.

[0101] (6) The obtained aviation kerosene had a heat value in a range from 43.0 to 43.7 MJ/kg, a density in a range from 780 to 810 kg/m3, a total acid number in a range from 0.002-0.005 mgKOH/g, total nitrogen content in a range from 1 to 2 ppm, and total sulphur content in a range from 0.04% to 0.08%, and could be used in six types of airplanes and engines thereof. Carbon emissions over whole life cycle were reduced by more than 50%. Such biofuel could be fully used in business jet, and emissions per kilogram of the biofuel per kilometer during whole life cycle could be reduced by 1.5 g.

EXAMPLE 2

[0102] (1) Selection of microalgae was as follows. Multicellular Tribonema with oil content in a range from 30% to 65%, a growth rate in a range from 20 to 30 g/m.sup.2.Math.d, and carbon spectrums of C14, C16, and C18 were selected.

[0103] (2) Carbon dioxide (CO.sub.2) from a coal-fired power plant was purified or directly fed to a Tribonema cultivation pond. An amount of CO.sub.2 was adjusted through control of pH value, and the pH value was controlled in a range from 5.5 to 7.8. Tribonema were large, and thus could be harvested directly. Therefore, a dewatering process was no longer needed. Tribonema were rapidly filtered by using nylon bolting cloth of 200 to 400 mesh. After squeezing and dewatering, Tribonema had a concentration of 350 g/L. After filtering and disinfecting, water collected by harvest and dewatering was returned to the cultivation pond.

[0104] (3) Microalgae pulp was delivered into a hydrothermal reactor which had been heated to a preset temperature by means of a high-pressure pump. The temperature of the reactor was controlled in a range from 270° C. to 300° C. Nitrogen was fed to the reactor with a retention time in a range from 5 to 30 min to keep an inert atmosphere in the reactor. Since it takes time for cell wall rupture of the Nannochloropsis, a heating rate was less than 100° C/min. Materials from an outlet of the hydrothermal reactor were fed to a multiphase separator, which was provided with a filter therein. Gas was discharged from an upper part of the multiphase separator. Solid residues were precipitated at a bottom part of the multiphase separator and then discharged at the bottom part thereof. A liquid portion overflowed from the filter provided at the upper part of the multiphase separator, so that a liquid bio-oil and water were obtained. An oil phase and a water phase were separated to obtain a biocrude. After purification and disinfection, the water phase was returned to the cultivation pond to provide nitrogen sources.

[0105] (4) The biocrude was subjected to a heteroatom removal process and a hydrogenation process first. In a hydrogenation reactor, a catalyst for removing heteroatoms was provided at an upper layer, and a hydrogenation catalyst was provided at a lower layer. The catalyst for removing heteroatoms was Ni/Al.sub.2O.sub.3, a hydrogen partial pressure was in a range from 8 to 10 MPa, a hydrogen to oil ratio was in a range from 400 to 800 m.sup.3/m.sup.3, a temperature was in a range from 260° C. to 300° C., and a superficial flow velocity was in a range from 0.25 to 2 h.sup.−1. The hydrogenation catalyst was Ni—Mo/Al.sub.2O.sub.3, a hydrogen partial pressure was in a range from 5 to 10 MPa, a hydrogen to oil ratio was in a range from 600 to 1000 m.sup.3/m.sup.3, a temperature was in a range from 280° C. to 400° C., and a superficial flow velocity was in a range from 0.25 to 2 h.sup.−1. After the heteroatom removing process and the hydrotreating process, a hydrocarbon distillate could be obtained. Next, a fractionation process was performed. A light distillate carbon number distribution was in a range from C8 to C16, and a high distillate carbon number distribution was in a range from C17 to C32. Besides, there was 5% to 15% of a naphtha fuel having carbon number distribution less than C7.

[0106] (5) The high hydrocarbon distillate was hydrocracked to obtain a low-distillate hydrocarbon fuel. The low distillate hydrocarbon fuel obtained by hydrocracking and a low-distillate hydrocarbon fuel obtained by hydrotreating were performed with a hydroisomerization process to obtain a jet fuel that met performance requirements. A hydrocracking catalyst was Ni—Mo—W/SiO.sub.2—Al.sub.2O.sub.3. A hydroisomerization catalyst was Mo—W—Ni/Al.sub.2O.sub.3—F. A hydrogen partial pressure was in a range from 3 to 15 MPa, a hydrogen to oil ratio was in a range from 1000 to 1500 m.sup.3/m.sup.3, a temperature was in a range from 400° C. to 450° C., and a superficial flow velocity was in a range from 0.25 to 2 h.sup.−1.

[0107] (6) The obtained aviation kerosene had a heat value in a range from 43.0 to 43.7 MJ/kg, a density in a range from 780 to 810 kg/m.sup.3, a total acid number in a range from 0.002-0.005 mgKOH/g, total nitrogen content in a range from 1 to 2 ppm, and total sulphur content in a range from 0.04% to 0.08%, and could be used in six types of airplanes and engines thereof. Carbon emissions over full life cycle were reduced by more than 60% to 80%. Such biofuel could be fully used in cooperation aircrafts, and emissions per kilogram of the biofuel per kilometer during lifecycle could be reduced by 1.86 g.

[0108] It should be noted that the above embodiments are only used for explaining the present disclosure, rather than limiting the present disclosure. The present disclosure has been described with reference to the exemplary embodiments, but it should be understood that words used in the embodiments are explanatory words, rather than definitive words. The present disclosure can be modified within the scope of the claims of the present disclosure according to regulation. Also, amendments can be made to the present disclosure without departing from the scope and spirit of the present disclosure. Although the present disclosure relates to specific methods, materials, and embodiments, it is not intended that the present disclosure be limited to the specific embodiments disclosed here. The present disclosure can be extended to all other methods and applications having same functions.