Biogas comprehensive utilization system for preparing sustainable aviation fuel raw oil

Abstract

The invention discloses a biogas comprehensive utilization system for preparing sustainable aviation fuel raw oil, comprising: a biomass fermentation device for producing biogas; the moving bed water-based chemical looping hydrogen production device is used for producing hydrogen by taking methane and steam in the biogas as raw materials and capturing carbon dioxide produced in the hydrogen production process; the carbon dioxide dry reforming device is used for converting methane and carbon dioxide in the biogas and carbon dioxide from the moving bed water-based chemical looping hydrogen production device into synthesis gas; the Fischer-Tropsch synthesis reaction device is used for mixing synthesis gas from the carbon dioxide dry reforming device with hydrogen from the moving bed water-based chemical-looping hydrogen production device to synthesize hydrocarbon products, the biogas is pretreated and then divided into two paths, one path enters the moving bed water-based chemical-looping hydrogen production device, and the other path enters the moving bed water-based chemical-looping hydrogen production device; and the other path enters the carbon dioxide dry reforming device. The utilization rate of biomass can be increased.

Description

Technical Field

[0001] This invention relates to the field of biomass utilization equipment, and more specifically, to a biogas integrated utilization system for preparing sustainable aviation fuel feedstock. Background Technology

[0002] Biogas primarily consists of methane and carbon dioxide. In traditional biogas utilization methods, carbon dioxide is typically removed directly, utilizing only the methane to produce hydrogen and syngas through methods such as SMR (Selective Methane Reduction). This method not only wastes the carbon source in the biogas but also results in significant carbon dioxide emissions.

[0003] Technologies for producing sustainable aviation fuel mainly include HEFA, Fischer-Tropsch synthesis, and alcohol-to-hydrocarbon synthesis. Although HEFA technology has been commercialized, its raw materials are waste oils, which limits the range of raw material sources. Due to the limitation on the scale of raw materials, the development scale of HEFA technology is also limited, which can easily lead to insufficient plant utilization.

[0004] Current Fischer-Tropsch synthesis technology requires syngas, primarily composed of hydrogen and carbon monoxide, as feedstock. The Fischer-Tropsch reaction produces hydrocarbons, which serve as feedstock for sustainable aviation fuel. The main sources of syngas are biomass gasification, hydrogen production via water electrolysis, and the capture of carbon dioxide from factory exhaust or directly from the atmosphere. However, these methods all have certain drawbacks. Firstly, biomass gasification emits significant amounts of carbon dioxide, resulting in incomplete carbon source utilization. Secondly, the energy consumption and cost of water electrolysis remain relatively high, and the cost of directly capturing carbon dioxide from the atmosphere is also very high. Summary of the Invention

[0005] The purpose of this invention is to provide a biogas comprehensive utilization system for preparing sustainable aviation fuel feedstock, which can improve the utilization rate of biomass.

[0006] The embodiments of the present invention are implemented as follows: This application provides a biogas comprehensive utilization system for preparing sustainable aviation fuel feedstock, comprising: Biomass fermentation equipment used to produce biogas; A moving bed water-based chemical loop hydrogen production unit is used to produce hydrogen from methane and steam in biogas and to capture the carbon dioxide produced during the hydrogen production process. A carbon dioxide dry reforming unit is used to convert methane and carbon dioxide in biogas, as well as carbon dioxide from the moving bed water-based chemical looping hydrogen production unit, into syngas. The Fischer-Tropsch synthesis reactor is used to mix syngas from the carbon dioxide dry reforming unit with hydrogen from the moving bed water-based chemical looping hydrogen production unit to synthesize hydrocarbon products; wherein the biogas is pretreated and divided into two streams, one stream enters the moving bed water-based chemical looping hydrogen production unit, and the other stream enters the carbon dioxide dry reforming unit.

[0007] In a possible implementation, the moving bed water-based chemical looping hydrogen production device includes a moving bed reactor and an oxygen carrier, wherein methane in the biogas undergoes a water-based chemical looping reaction with by-product steam from the Fischer-Tropsch synthesis reactor under the action of the oxygen carrier to produce hydrogen and carbon dioxide.

[0008] In a possible implementation, the moving bed water-based chemical loop hydrogen production apparatus further includes a gas separation unit for separating the generated hydrogen from carbon dioxide, which is then sent to the carbon dioxide dry reforming unit.

[0009] In a possible implementation, in the carbon dioxide dry reforming unit, methane and carbon dioxide undergo a dry reforming reaction under the action of a catalyst to produce carbon monoxide and hydrogen, and the supplemented hydrogen and carbon dioxide are further converted into carbon monoxide through a reverse conversion reaction.

[0010] In a possible implementation, the system further includes a syngas mixing and regulating unit for mixing syngas from the carbon dioxide dry reforming unit with hydrogen from the moving bed water-based chemical looping hydrogen production unit, adjusting the hydrogen-carbon molar ratio to (1.8-2.2):1.

[0011] In a possible implementation, the hydrocarbon products generated by the Fischer-Tropsch synthesis reactor are separated to obtain sustainable aviation fuel feedstock, while the low-pressure steam generated during the reaction is sent to the moving bed water-based chemical looping hydrogen production unit as a reaction feedstock.

[0012] In a possible implementation, the biogas is composed of 50%-70% methane by volume and 30%-50% carbon dioxide by volume.

[0013] In a possible implementation, the system does not emit carbon dioxide; all the carbon source in the biogas is converted into carbon monoxide in the syngas, and ultimately into hydrocarbon products.

[0014] In a possible implementation, the system further includes a desulfurization pretreatment unit for removing hydrogen sulfide before the biogas enters the moving bed water-based chemical loop hydrogen production unit and the carbon dioxide dry reforming unit.

[0015] In a possible implementation, the system is used to process biogas produced by fermentation of kitchen waste, agricultural waste, or livestock and poultry manure, with a biogas processing capacity of 1000-5000 kmol / day.

[0016] The beneficial effects of the embodiments of the present invention are: 1. The system couples three technologies: moving bed water-based chemical looping hydrogen production technology, carbon dioxide dry reforming technology, and Fischer-Tropsch synthesis technology. It makes full use of all carbon sources in the biogas produced by biomass resources, including the utilization of methane and especially carbon dioxide, so that the carbon sources in the biogas are basically converted into hydrocarbons, and the whole system does not emit carbon dioxide.

[0017] 2. Utilizing methane from biogas, hydrogen is produced via a moving bed water-based chemical looping hydrogen production technology to serve as the hydrogen source for syngas, while simultaneously capturing carbon dioxide. This process achieves complete self-heating equilibrium, requiring no additional heat source. Furthermore, the cost of producing hydrogen is lower than that of hydrogen produced through water electrolysis.

[0018] 3. The carbon dioxide captured during the moving bed water-based chemical looping hydrogen production process, as well as the carbon dioxide in biogas, is converted into syngas through carbon dioxide dry reforming technology, making full use of the carbon source and significantly reducing the cost of carbon dioxide capture.

[0019] 4. Using biomass resources to produce biogas as raw material, the source of raw materials is relatively wide, and there is no need for biomass gasification or gasification furnaces, so the equipment investment is relatively low.

[0020] 5. The low-pressure steam generated by heat extraction during the Fischer-Tropsch synthesis process can be directly used as a raw material for moving bed water-based chemical loop hydrogen production technology, and mixed with methane in biogas to produce hydrogen. Attached Figure Description

[0021] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of a biogas comprehensive utilization system for preparing sustainable aviation fuel feedstock, according to an embodiment of the present invention.

[0023] Icons: 1. Biomass fermentation equipment; 2. Moving bed water-based chemical looping hydrogen production unit; 3. Carbon dioxide dry reforming unit; 4. Fischer-Tropsch synthesis reaction unit. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0025] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0026] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0027] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this invention is in use. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention. In addition, the terms "first," "second," "third," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0028] Furthermore, terms such as "horizontal" and "vertical" do not imply that components must be absolutely horizontal or suspended, but rather that they can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0029] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0030] like Figure 1As shown, the biogas comprehensive utilization system of this invention mainly includes a biomass fermentation device 1, a moving bed aqueous chemical looping hydrogen production device 2, a carbon dioxide dry reforming device 3, and a Fischer-Tropsch synthesis reactor 4. The biomass fermentation device 1 is used to convert biomass raw materials (such as kitchen waste, agricultural waste, livestock manure, etc.) into biogas through anaerobic fermentation. Optionally, the biomass raw materials are kitchen waste, agricultural waste, livestock manure, etc. The moving bed aqueous chemical looping hydrogen production device 2 is used to produce hydrogen through an aqueous chemical looping reaction using methane in the biogas and steam circulating within the system as raw materials, while achieving complete carbon dioxide capture. The carbon dioxide dry reforming device 3 is used to convert methane and carbon dioxide in the biogas, as well as carbon dioxide from the hydrogen production device, into syngas through a dry reforming reaction. The Fischer-Tropsch synthesis reactor 4 is used to convert the syngas into a hydrocarbon mixture under the action of a catalyst, which, after separation, yields sustainable aviation fuel feedstock. After desulfurization and other pretreatment, the biogas is divided into two streams. One stream enters the moving bed water-based chemical loop hydrogen production unit 2, and the other stream enters the carbon dioxide dry reforming unit 3, realizing the cascade conversion and coupled utilization of hydrocarbon resources.

[0031] This embodiment takes food waste treatment as an example, with a biogas production of approximately 30,000 Nm³ / day. Its main components are methane (approximately 60 vol%) and carbon dioxide (approximately 40 vol%). The biogas first passes through a desulfurization pretreatment unit (such as iron oxide or activated carbon desulfurization) to reduce the hydrogen sulfide content to below 10 ppm to avoid subsequent catalyst poisoning.

[0032] The moving bed water-based chemical looping hydrogen production unit 2 uses a moving bed reactor with an internal oxygen carrier (such as a composite carrier like Fe2O3 / Al2O3 or NiO / CeO2). The reaction process includes two stages: Reduction stage: Methane (CH4) from biogas and low-pressure steam (approximately 0.5–1.0 MPa, 150–200 °C) from the Fischer-Tropsch synthesis unit enter a moving bed reactor, where a water-based chemical looping reaction occurs under the action of an oxygen carrier, producing hydrogen and carbon dioxide. CH4 + 2H2O + oxygen support → 4H2 + CO2 + reduced support; The reaction temperature is controlled at 600–800℃, and the pressure is atmospheric pressure to 0.5 MPa.

[0033] Oxidation and support regeneration stage: The reduced support continuously moves to the regeneration zone in the moving bed, where it is re-oxidized by contact with air or oxygen-enriched gas, regaining its activity before being recycled. This process is a strongly exothermic reaction, and the heat can be used to maintain the system's self-heating equilibrium.

[0034] The generated mixed gas is separated into high-purity hydrogen (>99%) by a gas separation unit (such as pressure swing adsorption or membrane separation), and the captured carbon dioxide is sent to the carbon dioxide dry reforming unit 3 for further utilization.

[0035] The carbon dioxide dry reforming unit 3 is a fixed-bed or fluidized-bed reactor, loaded with a dry reforming catalyst (such as a Ni-based, Co-based, or noble metal catalyst). The reaction process includes: Dry reforming reaction: Methane and carbon dioxide in biogas react in the presence of a catalyst. CH4+CO2→2H2+2COCH4+CO2→2H2+2CO; The reaction temperature is 700–900℃ and the pressure is 0.1–1.0 MPa.

[0036] Reverse water-gas shift reaction: Due to excess carbon dioxide in the biogas, some of the carbon dioxide undergoes a reverse shift reaction with supplemental hydrogen from the hydrogen production unit, further converting into carbon monoxide. CO2+H2→CO+H2O; CO2+H2→CO+H2O; The reaction is carried out in the same or similar reactors, and the hydrogen-to-carbon ratio of the syngas is controlled by adjusting the hydrogen feed rate.

[0037] Syngas from the carbon dioxide dry reforming unit 3 (H2 / CO ≈ 1:1) and hydrogen from the moving bed water-based chemical looping hydrogen production unit 2 are uniformly mixed in a mixer. The amount of hydrogen added is adjusted by a flow controller to ensure that the final hydrogen-to-carbon molar ratio of the syngas entering the Fischer-Tropsch synthesis unit is stabilized at (1.8–2.2):1, preferably 2:1, to meet the optimal stoichiometric requirements of the Fischer-Tropsch synthesis reaction.

[0038] Syngas enters a Fischer-Tropsch synthesis reactor (such as a slurry-bed or fixed-bed reactor), where, under the action of an iron-based or cobalt-based catalyst, polymerization occurs at 180–250 °C and 2.0–3.0 MPa, producing a mixed hydrocarbon mixture mainly composed of straight-chain alkanes and alkenes. The reaction equation can be simplified as follows: CO+2H2→(CH2)+H2OnCO+2nH2→(CH2)n+nH2O; The reaction releases a large amount of heat, which generates low-pressure steam (approximately 0.8 MPa, 170°C) through the built-in cooling coil. This steam is directly sent to the moving bed water-based chemical loop hydrogen production unit 2 as a raw material, realizing the recycling of thermal energy within the system.

[0039] After condensation and separation, the reaction products yield light hydrocarbons (C1–C4), naphtha, diesel oil, and heavy wax. The heavy wax can be further converted into sustainable aviation fuel feedstock (C8–C4) through hydrocracking. 16 Hydrocarbons).

[0040] To illustrate the technical effects of this invention, taking kitchen waste biogas as an example (composition: CH4 60%, CO2 40%, flow rate 1340 kmol / day), material balance calculations and comparisons were performed on this system scheme and the traditional scheme of combining methane dry reforming with direct hydrogen supplementation.

[0041] (1) Material balance of the system scheme of the present invention.

[0042] In the coupled system of this invention, both biogas and by-product steam enter the system, and its theoretical material balance (without considering side reactions) is shown in Table 1:

[0043] Table 1 Calculations show that the amount of H2 generated is 1876 kmol / day, and CO is 1340 kmol / day. To achieve the optimal hydrogen-to-carbon ratio of 2:1 in Fischer-Tropsch synthesis, an additional 804 kmol / day of hydrogen is required, which is entirely supplied by the moving bed water-based chemical looping hydrogen production unit 2 within the system.

[0044] (2) Material balance of traditional methane dry reforming scheme.

[0045] In contrast, in traditional methane dry reforming schemes, only a portion of the methane in the biogas is used to react with all the carbon dioxide, and the insufficient hydrogen needs to be supplemented externally. Its theoretical material balance is shown in Table 2:

[0046] Table 2 In this scheme, the amount of H2 generated is 1072 kmol / day, and the amount of CO generated is 1072 kmol / day. To achieve a hydrogen-to-carbon ratio of 2:1, 1072 kmol / day of hydrogen needs to be supplied from an external source.

[0047] (3) Comparative analysis of technical effects Table 3 shows a performance comparison of the two schemes mentioned above:

[0048] Table 3 The comparative data in Table 3 clearly shows that the system of the present invention has the following significant advantages: High carbon source utilization rate: 100% utilization of methane in biogas has been achieved.

[0049] Strong hydrogen self-sufficiency: The system's internal hydrogen production greatly reduces the demand for external hydrogen sources (by about 25%).

[0050] High syngas yield: With the same biogas processing capacity, the total syngas production is increased by approximately 28.3%, which means that the potential production of sustainable aviation fuel feedstock is also significantly increased accordingly.

[0051] In summary, this system achieves a complete carbon cycle: all the carbon (CH4 and CO2) in the biogas is eventually converted into carbon in hydrocarbon products, and the CO2 captured during hydrogen production is also used for dry reforming. There is no carbon dioxide emission within the system boundary, which is in line with the concept of carbon closed-loop utilization.

[0052] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A biogas comprehensive utilization system for preparing a sustainable aviation fuel raw oil, characterized by, The system comprises: a biomass fermentation device for producing biogas; a moving bed water-based chemical looping hydrogen production device for producing hydrogen from methane and steam in the biogas and capturing carbon dioxide produced in the hydrogen production process; a carbon dioxide dry reforming device for converting methane in the biogas and carbon dioxide, as well as carbon dioxide from the moving bed water-based chemical looping hydrogen production device, into synthesis gas; a Fischer-Tropsch synthesis reaction device for synthesizing hydrocarbon products after mixing the synthesis gas from the carbon dioxide dry reforming device with hydrogen from the moving bed water-based chemical looping hydrogen production device; wherein the biogas is divided into two routes after pretreatment, one route enters the moving bed water-based chemical looping hydrogen production device, and the other route enters the carbon dioxide dry reforming device.

2. The biogas comprehensive utilization system for preparing a sustainable aviation fuel raw oil according to claim 1, characterized by, The moving bed water-based chemical looping hydrogen production device comprises a moving bed reactor and an oxygen carrier, and the methane in the biogas and steam produced as a byproduct of the Fischer-Tropsch synthesis reaction device undergo water-based chemical looping reaction under the action of the oxygen carrier to generate hydrogen and carbon dioxide.

3. The biogas comprehensive utilization system for producing sustainable aviation fuel raw oil according to claim 2, characterized in that, The moving bed water-based chemical looping hydrogen production device further comprises a gas separation unit for separating the generated hydrogen and carbon dioxide, and the carbon dioxide is sent to the carbon dioxide dry reforming device.

4. The biogas comprehensive utilization system for producing sustainable aviation fuel raw oil according to claim 1, characterized in that, In the carbon dioxide dry reforming device, methane and carbon dioxide undergo dry reforming reaction under the action of a catalyst to generate carbon monoxide and hydrogen, and supplemental hydrogen and carbon dioxide are converted into carbon monoxide through reverse shift reaction.

5. The biogas comprehensive utilization system for preparing sustainable aviation fuel raw oil according to claim 1, characterized in that, The system further comprises a synthesis gas mixing and adjusting unit for mixing the synthesis gas from the carbon dioxide dry reforming device with the hydrogen from the moving bed water-based chemical looping hydrogen production device to adjust the hydrogen-carbon molar ratio to (1.8-2.2):

1.

6. The biogas comprehensive utilization system for preparing sustainable aviation fuel raw oil according to claim 1, characterized in that, The hydrocarbon products generated by the Fischer-Tropsch synthesis reaction device are separated to obtain sustainable aviation fuel raw oil, and the steam produced in the reaction process is sent to the moving bed water-based chemical looping hydrogen production device as a reaction raw material.

7. The biogas integrated utilization system for producing a sustainable aviation fuel feedstock oil according to claim 1, characterized by, The composition of the biogas is 50%-70% methane by volume and 30%-50% carbon dioxide by volume.

8. The biogas integrated utilization system for producing a sustainable aviation fuel feedstock oil according to claim 1, characterized by, The system does not discharge carbon dioxide to the outside, and the carbon source in the biogas is completely converted into carbon monoxide in the synthesis gas and ultimately converted into hydrocarbon products.

9. The biogas comprehensive utilization system for preparing sustainable aviation fuel raw oil according to claim 8, characterized in that, The system further comprises a desulfurization pretreatment unit for removing hydrogen sulfide before the biogas enters the moving bed water-based chemical looping hydrogen production device and the carbon dioxide dry reforming device.

10. The biogas integrated utilization system for producing a sustainable aviation fuel feedstock oil according to claim 8, characterized by, The system is used for processing biogas produced by fermentation of kitchen waste, agricultural waste or livestock manure, and the biogas processing scale is 1000-5000 kmol / day.

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