Process for synthesizing sustainable aviation fuel through pure biomass low-pressure high-temperature steam gasification

Abstract

The invention discloses a process for synthesizing sustainable aviation fuel through pure biomass low-pressure high-temperature steam gasification. The process comprises the following steps: S1, raw material pretreatment; s2, low-pressure high-temperature steam gasification; superheated steam is introduced into the gasification furnace, pyrolysis, oxidation and reduction reactions are carried out under the anoxic condition, and synthesis gas is generated; s3, washing and purifying the synthesis gas; the synthesis gas sequentially passes through a cyclone separator, a venturi scrubber and an activated carbon adsorption tower, so that the gas cleanliness is ensured; s4, pressurizing, desulfurizing and decarburizing; the synthesis gas is pressurized for the first time through a compressor and enters an MDEA solution tower to remove HS and COs; s5, synthesizing and refining the SAF; the pressurized synthesis gas enters a Fischer-Tropsch synthesis module to generate straight-chain hydrocarbons; then hydroisomerization and rectification separation are carried out to obtain SAF; and S6, recycling by-products. According to the process, through combination of low-pressure high-temperature steam gasification and modular design, the purpose of efficiently converting biomass into SAF is achieved, and the process has the advantages of being simple, high in environmental protection property, excellent in economical efficiency and the like.

Description

Technical Field

[0001] The present invention relates to the field of chemical technology, and more particularly to a process for synthesizing sustainable aviation fuel by low-pressure and high-temperature steam gasification of pure biomass. Background Art

[0002] Traditional biomass gasification technology suffers from common issues such as high tar content, reduced syngas quality due to nitrogen introduction, and low gas production efficiency, requiring additional hydrogen production to replenish the gas, which increases the cost of SAF production. Furthermore, the equipment has low integration and occupies a large footprint. For example, conventional biomass gasification pressures are typically above 3 MPa, while the present invention utilizes a low-pressure environment of less than 0.05 MPa, combined with high-temperature steam at 1000°C, significantly improving gasification efficiency and suppressing tar formation. Furthermore, the present invention utilizes a modular design that enables rapid deployment and flexible combination of equipment, addressing the high energy consumption and high costs associated with traditional processes. Accordingly, the present invention proposes a process for synthesizing sustainable aviation fuel using pure biomass through low-pressure, high-temperature steam gasification. Summary of the Invention

[0003] The purpose of the present invention is to overcome the deficiencies in the prior art and to provide a process for synthesizing sustainable aviation fuel by low-pressure, high-temperature steam gasification of pure biomass.

[0004] To solve the above technical problems, the object of the present invention is achieved as follows: The process of synthesizing sustainable aviation fuel by low-pressure and high-temperature steam gasification of pure biomass involved in the present invention comprises the following steps: S1. Raw material pretreatment; the biomass raw material is crushed to 3-5 cm, dried to a moisture content of less than 20%, and transported to the gasifier feed port via an elevator; S2. Low-pressure, high-temperature steam gasification: Superheated steam at a pressure of <0.05 MPa and a temperature of 1000°C is introduced into the gasifier, where pyrolysis, oxidation, and reduction reactions occur under oxygen-deficient conditions to produce synthesis gas, which includes CO and H2. S3. Syngas scrubbing and purification: Syngas passes through a cyclone separator for dust removal, a Venturi scrubber to cool it to 45°C, and an activated carbon adsorption tower to remove residual tar, ensuring gas cleanliness. S4. Pressurization and desulfurization and decarbonization: The syngas is pressurized to 2 MPa by a compressor and then enters an MDEA (methyldiethanolamine) solution tower to remove H2S and CO2. After purification, the gas is pressurized a second time to 5.2 MPa to meet the pressure requirements of the Fischer-Tropsch synthesis reaction. S5. SAF synthesis and refining: The pressurized syngas enters the Fischer-Tropsch synthesis module to generate linear hydrocarbons. This is then separated through hydroisomerization and distillation to produce SAF that meets ASTM D7566 standards. S6. By-product recovery: Activated carbon is produced as a by-product during the gasification process, with a yield of 200 kg per ton of biomass. It is collected through a cyclone separator and screening system and used for water treatment or industrial adsorption.

[0005] The present invention is further configured as follows: in step S1, the biomass raw material includes straw and wood chips.

[0006] The present invention is further configured as follows: in step S2, high-temperature steam is used as a gasifying agent to further reduce the tar content to <1 mg / Nm³, while increasing the carbon conversion rate to more than 95%.

[0007] The present invention is further configured as follows: in step S5, the Fischer-Tropsch synthesis catalyst is a Co-based catalyst, the reaction temperature is 220-250° C., and the reaction pressure is 5.2 MPa.

[0008] The present invention is further configured as follows: in step S5, the hydroisomerization catalyst is a Pt / Al2O3 catalyst, and the reaction temperature is 300-350°C.

[0009] In summary, the present invention has the following beneficial effects: 1. The present invention adopts a low-pressure environment of <0.05MPa, combined with 1000℃ high-temperature steam, which significantly reduces energy consumption and improves carbon conversion rate.

[0010] 2. The design without tar and nitrogen generation is achieved through catalytic cracking and pure steam gasification, which is superior to traditional processes.

[0011] 3. The skid-mounted modular design enables rapid deployment and flexible adjustment of equipment, overcoming the high capital construction costs and low scalability problems of traditional processes.

[0012] 4. Efficient recovery of by-product activated carbon improves the economic efficiency of the system.

[0013] 5. The process parameters (such as MDEA desulfurization and Fischer-Tropsch synthesis conditions) are based on mature industrial technologies and have passed pilot plant verification.

[0014] 6. Modular design supports distributed production and is suitable for rural and remote areas. DETAILED DESCRIPTION

[0015] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the preferred embodiments of the present invention are described below in conjunction with specific examples. However, it should be understood that these descriptions are only for the purpose of further illustrating the features and advantages of the present invention, and are not intended to limit the patent claims of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0016] The present invention is further described below in conjunction with preferred embodiments.

[0017] Example 1 The process for synthesizing sustainable aviation fuel by low-pressure, high-temperature steam gasification of pure biomass involved in this embodiment includes the following steps: S1. Raw material pretreatment; the biomass raw material is crushed to 3-5 cm, dried to a moisture content of less than 20%, and transported to the gasifier feed port via an elevator; S2. Low-pressure, high-temperature steam gasification: Superheated steam at a pressure of <0.05 MPa and a temperature of 1000°C is introduced into the gasifier, where pyrolysis, oxidation, and reduction reactions occur under oxygen-deficient conditions to produce synthesis gas, which includes CO and H2. S3. Syngas scrubbing and purification: Syngas passes through a cyclone separator for dust removal, a Venturi scrubber to cool it to 45°C, and an activated carbon adsorption tower to remove residual tar, ensuring gas cleanliness. S4. Pressurization and desulfurization and decarbonization: The syngas is pressurized to 2 MPa by a compressor and then enters an MDEA (methyldiethanolamine) solution tower to remove H2S and CO2. After purification, the gas is pressurized a second time to 5.2 MPa to meet the pressure requirements of the Fischer-Tropsch synthesis reaction. S5. SAF synthesis and refining: The pressurized syngas enters the Fischer-Tropsch synthesis module to generate linear hydrocarbons. This is then separated through hydroisomerization and distillation to produce SAF that meets ASTM D7566 standards. S6. By-product recovery: Activated carbon is produced as a by-product during the gasification process, with a yield of 200 kg per ton of biomass. It is collected through a cyclone separator and screening system and used for water treatment or industrial adsorption.

[0018] Furthermore, in step S1, the biomass raw materials include straw and wood chips.

[0019] Furthermore, in step S2, high-temperature steam is used as a gasifying agent to further reduce the tar content to <1 mg / Nm³, while increasing the carbon conversion rate to more than 95%.

[0020] Furthermore, in step S5, the Fischer-Tropsch synthesis catalyst is a Co-based catalyst, the reaction temperature is 220-250°C, and the reaction pressure is 5.2 MPa.

[0021] Furthermore, in step S5, the hydroisomerization catalyst is a Pt / Al2O3 catalyst, and the reaction temperature is 300-350°C.

[0022] Specific implementation plan: a. Raw material selection: Agricultural waste such as rice husks and corn stalks are preferred, with moisture content controlled below 20% and crushed to 3-5 cm.

[0023] b. Gasifier operation: Steam is generated by the waste heat from biomass combustion to drive the superheater. The pressure is precisely controlled at 0.04 MPa by a pressure reducing valve, and the temperature is monitored and adjusted in real time by a thermocouple.

[0024] c. Synthesis gas treatment: The temperature of the MDEA solution regeneration tower is controlled at 120°C, and the circulation flow rate is automatically adjusted according to the acid gas content in the synthesis gas.

[0025] d.SAF synthesis: The space velocity of the Fischer-Tropsch synthesis reactor is set to 5000 h⁻¹, the hydrogen-to-carbon ratio (H2 / CO) is controlled at 2.1-2.3, and the catalyst life can reach 10,000 hours.

[0026] e. Activated carbon recovery: The carbon powder collected by the cyclone separator is classified by a vibrating screen. The activated carbon with a particle size greater than 200 mesh is used for industrial adsorption, and the activated carbon with a particle size less than 200 mesh is returned to the gasifier for reuse.

[0027] The process for synthesizing sustainable aviation fuel by low-pressure, high-temperature steam gasification of pure biomass involved in the present invention achieves the goal of efficiently converting biomass into SAF by combining low-pressure, high-temperature steam gasification with modular design. It has the characteristics of simple process, strong environmental protection, and excellent economy, and provides a feasible technical solution for decarbonization of the aviation industry.

[0028] Unless otherwise specified, in the present invention, if there are terms such as "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicating orientation or positional relationship, they are based on the orientation or positional relationship actually shown and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the terms describing the orientation or positional relationship in the present invention are only used for illustrative purposes and cannot be understood as limiting this patent. For those skilled in the art, the specific meanings of the above terms can be understood in combination with the embodiments and according to specific circumstances.

[0029] Unless otherwise specified or limited, the terms "disposed," "connected," and "connected" in this disclosure should be understood broadly. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to direct connections or indirect connections through an intermediary; and they may refer to internal communication between two components. Those skilled in the art will understand the specific meanings of these terms in this disclosure based on the specific circumstances.

[0030] The above describes in detail the preferred embodiments of the present invention. It should be understood that those skilled in the art can make numerous modifications and variations based on the concepts of the present invention without inventive effort. Therefore, any technical solutions that can be derived by those skilled in the art through logical analysis, reasoning, or limited experimentation based on the concepts of the present invention and the prior art should be within the scope of protection defined by the claims.

Claims

1. A process for synthesizing sustainable aviation fuel by low-pressure, high-temperature steam gasification of pure biomass, characterized in that: The following steps are involved: S1. Raw material pretreatment; the biomass raw material is crushed to 3-5 cm, dried to a moisture content of less than 20%, and transported to the gasifier feed port via an elevator; S2. Low-pressure, high-temperature steam gasification: Superheated steam at a pressure of <0.05 MPa and a temperature of 1000°C is introduced into the gasifier, where pyrolysis, oxidation, and reduction reactions occur under oxygen-deficient conditions to produce synthesis gas, which includes CO and H2. S3. Synthesis gas washing and purification; The synthesis gas passes through a cyclone separator for dust removal, a Venturi scrubber for cooling to 45°C, and an activated carbon adsorption tower for removal of residual tar to ensure gas cleanliness. S4. Pressurization and desulfurization and decarbonization: The syngas is pressurized to 2 MPa by a compressor and then enters an MDEA (methyldiethanolamine) solution tower to remove H2S and CO2. After purification, the gas is pressurized a second time to 5.2 MPa to meet the pressure requirements of the Fischer-Tropsch synthesis reaction. S5. SAF synthesis and refining: The pressurized syngas enters the Fischer-Tropsch synthesis module to generate linear hydrocarbons. This is then separated through hydroisomerization and distillation to produce SAF that meets ASTM D7566 standards. S6. By-product recovery: Activated carbon is produced as a by-product during the gasification process, with a yield of 200 kg per ton of biomass. It is collected through a cyclone separator and screening system and used for water treatment or industrial adsorption.

2. The process for synthesizing sustainable aviation fuel from pure biomass by low-pressure, high-temperature steam gasification according to claim 1, characterized in that: In step S1 , the biomass raw materials include straw and wood chips.

3. The process for synthesizing sustainable aviation fuel from pure biomass by low-pressure, high-temperature steam gasification according to claim 1, characterized in that: In step S2, high-temperature steam is used as a gasification agent to further reduce the tar content to <1 mg / Nm³, while increasing the carbon conversion rate to above 95%.

4. The process for synthesizing sustainable aviation fuel from pure biomass by low-pressure, high-temperature steam gasification according to claim 1, characterized in that: In step S5, the Fischer-Tropsch synthesis catalyst is a Co-based catalyst, the reaction temperature is 220-250°C, and the reaction pressure is 5.2 MPa.

5. The process for synthesizing sustainable aviation fuel from pure biomass by low-pressure, high-temperature steam gasification according to claim 1, characterized in that: In step S5, the hydroisomerization catalyst is a Pt / Al2O3 catalyst, and the reaction temperature is 300-350°C.