A system and process for producing green fuel by biomass gasification coupled with SOEC co-electrolysis

Abstract

The present application provides a kind of biomass gasification coupling SOEC co-electrolysis system and process of green fuel, the present application is coupled with biomass gasification and solid oxide electrolytic cell (SOEC) co-electrolysis synthesis gas path, with forestry waste biomass as raw material, adopt oxygen-carrying-CO2 adsorption functional material, construct gasification-adsorption integrated and SOEC co-electrolysis deep coupling system;System includes gasification unit, first heat exchange unit, gas purification unit, regeneration oxidation unit, SOEC electrolysis unit and fuel synthesis unit;With wind power, photovoltaic and other green electricity as SOEC electrolysis unit driving energy, integration biomass directional conversion, CO2 in situ capture-function material regeneration cycle, SOEC high temperature co-electrolysis is integrated, rely on heat cascade utilization, achieve system material closed loop reuse;By adjusting the amount of water vapor in the system, obtain specific hydrogen carbon ratio synthesis gas, so as to realize the production of green fuel, whole process saves traditional water gas shift process, improve system energy efficiency, avoid carbon loss, reduce high temperature energy consumption.

Description

Technical Field

[0001] This invention relates to the fields of biomass gasification and SOEC co-electrolysis, and particularly to a system and process for producing green fuels by coupling biomass gasification with SOEC co-electrolysis. Background Technology

[0002] Biomass resource utilization for syngas production is a key pathway for renewable energy to replace fossil fuels, and its techno-economic efficiency and low-carbon characteristics directly determine its potential for industrial scaling. Currently, the crude syngas obtained from traditional biomass gasification has an extremely low hydrogen-to-carbon ratio (H2 / CO≈0.5~1.0), requiring adjustment via a water-gas shift reaction. This process generates a large amount of CO2, involves complex separation procedures, resulting in low energy efficiency, significant carbon loss, and ineffective utilization of the high-grade waste heat from the gasification products. Further improvements are needed. Summary of the Invention

[0003] In view of the problems existing in the background art, the present invention provides a system and process for producing green fuel by coupling biomass gasification with SOEC co-electrolysis, thereby solving at least one of the problems mentioned in the background art.

[0004] The specific details of the invention are as follows: In a first aspect, the present invention provides a system for producing green fuels by biomass gasification coupled with SOEC co-electrolysis, comprising: Gasification unit, first heat exchange unit, gas purification unit, regeneration oxidation unit, SOEC electrolysis unit and fuel synthesis unit; The gasification unit is used to convert biomass raw materials into high-temperature gaseous products containing CO, H2 and CO2 through a gasification reaction under the synergistic effect of functional materials, water vapor and oxygen. Some of the functional materials are used to capture the generated carbon dioxide, and some of the functional materials are used to adjust the hydrogen-carbon ratio in the obtained gaseous products. The first heat exchange unit is connected to the gasification unit and is used to exchange heat between the high-temperature gaseous product and pure water. After absorbing heat, the pure water forms first high-temperature water vapor and a portion of the first high-temperature water vapor is returned to the gasification unit for the biomass raw material to undergo a gasification reaction. The regeneration oxidation unit is connected to the gasification unit and the SOEC electrolysis unit respectively, and is used to receive the solid material discharged from the gasification unit and part of the high-temperature oxygen discharged from the anode of the SOEC electrolysis unit to regenerate the functional material and release carbon dioxide. The SOEC electrolysis unit is connected to the first heat exchange unit and is used to receive the remaining first high-temperature water vapor and the carbon dioxide discharged from the regeneration oxidation unit for co-electrolysis, so as to obtain high-temperature oxygen at the anode and hydrogen and carbon monoxide at the cathode. The gas purification unit is connected to the first heat exchange unit and is used to receive the gaseous products discharged from the first heat exchange unit and perform purification treatment to remove sulfur and nitrogen compounds and dust impurities to obtain high-purity syngas. The fuel synthesis unit is connected to the gas purification unit and the SOEC electrolysis unit, and is used to receive hydrogen and carbon monoxide discharged from the cathode of the SOEC electrolysis unit, as well as high-purity synthesis gas discharged from the gas purification unit, as raw materials for the synthesis of green fuel.

[0005] Optionally, it also includes: a second heat exchange unit and a third heat exchange unit; The second heat exchange unit is connected to the first heat exchange unit and the gas purification unit respectively, and is used to enable the gaseous products discharged from the first heat exchange unit to exchange heat with pure water in the second stage to obtain second high-temperature water vapor; the gaseous products after heat exchange and cooling are supplied to the gas purification unit for purification. The third heat exchange unit is connected to the second heat exchange unit, the SOEC electrolysis unit and the gasification unit respectively. It is used to exchange heat between the second high-temperature water vapor discharged from the second heat exchange unit and another part of the high-temperature oxygen discharged from the anode of the SOEC electrolysis unit. The obtained third high-temperature water vapor is used for co-electrolysis in the SOEC electrolysis unit. The oxygen after heat exchange is introduced into the gasification unit as a gasifying agent to participate in the reaction.

[0006] Optionally, it also includes: a fourth heat exchange unit; The fourth heat exchange unit is connected to the SOEC electrolysis unit and the fuel synthesis unit respectively. It is used to exchange heat between the hydrogen and carbon monoxide gas discharged from the cathode of the SOEC electrolysis unit and pure water. The resulting high-temperature steam is used for co-electrolysis in the SOEC electrolysis unit, and the cooled hydrogen and carbon monoxide gas is used for the fuel synthesis unit to synthesize green fuel.

[0007] In a second aspect, the present invention provides a process for producing green fuels by biomass gasification coupled with SOEC co-electrolysis, characterized in that it is applicable to the system for producing syngas by biomass gasification coupled with SOEC co-electrolysis as described in the first aspect above, comprising: In the gasification unit, the biomass feedstock undergoes a gasification reaction under the synergistic effect of functional materials, water vapor, and oxygen to obtain high-temperature gaseous products containing CO, H2, and CO2. Some of the generated CO2 is captured by the functional materials. The high-temperature gaseous product undergoes a first-stage heat exchange with pure water in the first heat exchange unit to obtain first high-temperature water vapor, and a portion of the first high-temperature water vapor is consumed by the gasification reaction. The remaining first high-temperature water vapor is co-electrolyzed with carbon dioxide in the SOEC electrolysis unit. High-temperature oxygen is obtained at the anode end of the SOEC electrolysis unit, and hydrogen and carbon monoxide are obtained at the cathode end. Part of the high-temperature oxygen is consumed by the gasification reaction. The solid material discharged from the gasification unit is regenerated in the regeneration oxidation unit under the action of oxygen to regenerate functional materials and release the captured carbon dioxide. The carbon dioxide is used for co-electrolysis in the SOEC electrolysis unit, and the oxygen is provided by the anode of the SOEC electrolysis unit. The gaseous products after the first stage of heat exchange are purified in the gas purification unit to remove sulfur and nitrogen compounds and dust impurities. The resulting high-purity syngas is used for the synthesis of green fuels. The functional materials include oxygen-carrying functional materials and carbon dioxide-capturing functional materials. The oxygen-carrying functional materials are selected from Fe2O3, Fe3O4, Mn2O3, Mn3O4, MnFe2O4, or Fe2O3@ZrO2; the carbon dioxide-capturing functional materials are selected from CaO, CaO, and CaO. MgO, CaO Al2O3, Li2ZrO3 or Li4SiO4.

[0008] Optionally, the temperature of the gaseous product after the first stage heat exchange is 250 ℃~350 ℃, and the temperature of the first high-temperature water vapor is 250 ℃~400 ℃.

[0009] Optionally, before the gaseous products after the first-stage heat exchange are purified in the gas purification unit, the process further includes: The gaseous product undergoes a second-stage heat exchange with pure water in the second heat exchange unit to obtain a second high-temperature water vapor. After the second-stage heat exchange, a gaseous product close to room temperature is obtained for purification by the gas purification unit. The second high-temperature steam exchanges heat with a portion of the high-temperature oxygen obtained at the anode of the SOEC electrolysis unit in the third heat exchange unit. The second high-temperature steam is further heated, and the resulting third high-temperature steam is supplied to the SOEC electrolysis unit for co-electrolysis. The oxygen cooled down after heat exchange is used as a gasifying agent to participate in the gasification reaction of biomass raw materials.

[0010] Optionally, the temperature of the gaseous product after the second-stage heat exchange is 25 ℃~45 ℃, and the temperature of the second high-temperature water vapor is 150 ℃~170 ℃; The temperature of the third high-temperature steam is 500 ℃~700 ℃, and the temperature of the oxygen after heat exchange and cooling is 550 ℃~750 ℃.

[0011] Optionally, the process further includes: The hydrogen and carbon monoxide gas discharged from the cathode of the SOEC electrolysis unit exchange heat with pure water in the fourth heat exchange unit. The high-temperature steam formed by the heating of the pure water is used for co-electrolysis in the SOEC electrolysis unit, and the cooled hydrogen and carbon monoxide gas is used to synthesize green fuel in the fuel synthesis unit.

[0012] Optionally, the temperature of the fourth high-temperature water vapor is 400 ℃~500 ℃, and the temperature of the cooled hydrogen and carbon monoxide gas is 400 ℃~500 ℃.

[0013] Optionally, the components in the high-purity syngas obtained through the purification process are distributed as follows: H2: 40%~45%; CO: 35%~45%; CO2: 5%~10%; CH4: <1%%; Sulfides: <0.1 ppm.

[0014] This invention provides a system for producing green fuel through biomass gasification coupled with SOEC co-electrolysis, comprising: a gasification unit, a first heat exchange unit, a gas purification unit, a regeneration oxidation unit, an SOEC electrolysis unit, and a fuel synthesis unit. The gasification unit, under the synergistic effect of functional materials, water vapor, and oxygen, gasifies the biomass feedstock into high-temperature gaseous products containing CO, H2, and CO2. Part of the functional materials are used to capture the generated carbon dioxide, and another part is used to adjust the hydrogen-to-carbon ratio in the resulting gaseous products. The first heat exchange unit is connected to the gasification unit and allows the high-temperature gaseous products to exchange heat with pure water. The pure water absorbs heat to form first high-temperature water vapor, and a portion of this first high-temperature water vapor is returned to the gasification unit for further gasification of the biomass feedstock. The regeneration oxidation unit is connected to both the gasification unit and the SOEC electrolysis unit and receives the gaseous products. The solid material discharged from the oxidation unit and a portion of the high-temperature oxygen discharged from the anode of the SOEC electrolysis unit are used to regenerate functional materials and release carbon dioxide. The SOEC electrolysis unit is connected to the first heat exchange unit and is used to receive the remaining first high-temperature water vapor and the carbon dioxide discharged from the regeneration oxidation unit for co-electrolysis, obtaining high-temperature oxygen at the anode and hydrogen and carbon monoxide at the cathode. The gas purification unit is connected to the first heat exchange unit and is used to receive the gaseous products discharged from the first heat exchange unit and purify them to remove sulfur and nitrogen compounds and dust impurities to obtain high-purity syngas. The fuel synthesis unit is connected to the gas purification unit and the SOEC electrolysis unit and is used to receive the hydrogen and carbon monoxide discharged from the cathode of the SOEC electrolysis unit and the high-purity syngas discharged from the gas purification unit as raw materials for the synthesis of green fuels. Compared with the prior art, the present invention has the following advantages: 1. The system has a high degree of integration, realizing a dual closed loop of materials (C, H, O) and energy (heat cascade utilization). Its energy efficiency is significantly higher than that of the traditional biomass gasification combined with water gas conversion (WGS) process to produce syngas, as well as SOEC co-electrolysis to produce syngas.

[0015] 2. By leveraging functional materials and deeply coupling gasification-adsorption integration with SOEC co-electrolysis, the traditional water-gas conversion process is eliminated, carbon loss is avoided, and the hydrogen-carbon ratio of the syngas can be flexibly controlled, allowing it to be directly used for green fuel synthesis.

[0016] 3. The regeneration oxidation unit utilizes oxygen generated at the SOEC anode to regenerate functional materials, achieving efficient recycling of functional materials and producing high-purity CO2 with a purity >95%, solving the problem of insufficient CO2 purity in SOEC raw materials and ensuring electrolysis stability; moreover, the regeneration process relies on the high-temperature O2 from SOEC and the solid materials from the gasifier to provide heat, resulting in low desorption energy consumption.

[0017] 4. The system is driven by green electricity and coupled with biomass carbon negative conversion technology to realize the conversion from low-grade biomass to high-value green fuel, which has significant environmental and economic benefits. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 The diagram shows the material flow direction within the biomass gasification coupled SOEC co-electrolysis fuel production system provided in an embodiment of the present invention. Figure 2 This diagram illustrates the material flow within another biomass gasification coupled SOEC co-electrolysis fuel production system provided in an embodiment of the present invention. Figure 3 This diagram illustrates the material flow within another biomass gasification coupled SOEC co-electrolysis fuel production system provided in an embodiment of the present invention. Figure 4 The diagram illustrates the energy cascade utilization and material flow of the biomass gasification coupled SOEC co-electrolysis fuel production process provided in an embodiment of the present invention. Detailed Implementation

[0020] 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 following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, any product that is the same as or similar to the present invention, derived by anyone under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention. Furthermore, all other embodiments obtained by those skilled in the art without inventive effort are within the protection scope of the present invention.

[0021] Specific experimental steps or conditions are not specified in the embodiments; they can be performed according to the conventional experimental steps or conditions described in the prior art. Reagents and other instruments used, unless otherwise specified, are all commercially available conventional reagent products. Furthermore, the accompanying drawings are merely illustrative diagrams of the embodiments of the present invention and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and therefore, repeated descriptions of them will be omitted. Some block diagrams shown in the drawings are functional entities and do not necessarily correspond to physically or logically independent entities.

[0022] Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of this specification.

[0023] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0024] See Figure 1 The system structure includes: a gasification unit, a first heat exchange unit, a gas purification unit, a regeneration oxidation unit, an SOEC electrolysis unit, and a fuel synthesis unit; wherein, the gasification unit, the first heat exchange unit, the gas purification unit, and the fuel synthesis unit are connected in series via pipelines, the regeneration oxidation unit is connected to the gasification unit and the SOEC electrolysis unit via pipelines, and the SOEC electrolysis unit is connected to the gasification unit and the fuel synthesis unit via pipelines.

[0025] See Figure 1In this embodiment, the gasification unit is used to gasify biomass raw materials into high-temperature gaseous products containing CO, H2, and CO2 under the synergistic effect of functional materials, water vapor, and oxygen. Part of the functional materials are used to capture the generated carbon dioxide, and part of the functional materials are used to adjust the hydrogen-to-carbon ratio in the resulting gaseous products. The gasification unit operates at 800℃~1300℃. The biomass feedstock is gasified and converted at a temperature of ℃. The input materials to the gasification unit include: biomass feedstock, O2 (provided by the SOEC electrolysis unit of this system), steam (provided by the first heat exchange unit), and functional materials (including oxygen-carrying functional materials and carbon dioxide capture functional materials; such as Fe2O3 / Fe3O4 and CaO). The output materials include: high-temperature gaseous products containing CO, H2, and CO2, and solid-phase materials composed of deactivated functional materials and ash. The oxygen-carrying functional materials, such as Fe2O3 / Fe3O4, provide lattice oxygen, partially oxidizing the biomass to CO and H2, while being reduced to Fe / FeO. This helps increase the proportion of carbon monoxide and hydrogen in the gasification conversion products. The CO2 in the gaseous products is captured by the carbon dioxide capture functional material CaO to form CaCO3. The temperature of the high-temperature gaseous products output from the gasification unit is between 750 ℃ ​​and 1100 ℃.

[0026] See Figure 1 In this embodiment, the first heat exchange unit is used to exchange heat between the high-temperature gaseous product and pure water. After absorbing heat, the pure water forms first high-temperature steam. The first heat exchange unit effectively utilizes the waste heat of the high-temperature gaseous product (approximately 750 ℃~1100 ℃) to produce steam at 250 ℃~400 ℃. The steam outlet is divided into two paths: one path is fed back to the gasification unit for the gasification conversion of biomass raw materials, and the other path is connected to the SOEC electrolysis unit for use as the electrolysis raw material in the SOEC electrolysis unit. After heat exchange, the temperature of the high-temperature gaseous product drops to 250 ℃~350 ℃.

[0027] See Figure 1In this embodiment, the regeneration oxidation unit receives the solid material discharged from the gasification unit and a portion of the high-temperature oxygen discharged from the anode of the SOEC electrolysis unit to oxidize and regenerate the functional materials, releasing carbon dioxide. The regeneration oxidation unit relies on the high-temperature O2 (approximately 650°C to 850°C) discharged from the anode of the SOEC electrolysis unit and the solid material (750°C to 1100°C) from the gasification unit for heat. Carbon dioxide-capturing functional materials, such as CaO, capture CO2 to generate CaCO3, which then decomposes at high temperature in the regeneration oxidation unit, releasing CO2. The oxygen-carrying functional materials reduced in the gasifier are oxidized to Fe2O3 / Fe3O4 by oxygen in the regeneration oxidation unit. The heat released during the reaction further supplements the heat required for the regeneration of the carbon dioxide-capturing functional materials. This exothermic reaction helps maintain the reactor temperature, and the entire regeneration oxidation unit requires no additional energy supply. The regenerated functional materials are recycled back to the gasification unit for secondary use; the released high-concentration, high-purity CO2 gas is supplied to the SOEC electrolysis unit for co-electrolysis.

[0028] See Figure 1 In this embodiment, the SOEC electrolysis unit is used to receive the remaining first high-temperature water vapor and the carbon dioxide discharged from the regeneration oxidation unit for co-electrolysis, obtaining high-temperature oxygen at the anode and hydrogen and carbon monoxide at the cathode. The SOEC electrolysis unit uses green electricity such as wind power and photovoltaic power to supply power to the SOEC stack, so that the co-electrolysis operating temperature of the SOEC electrolysis unit is 700 ℃~900 ℃. Furthermore, due to the heat carried by the co-electrolysis object itself, the consumption of green electricity by the SOEC electrolysis unit is reduced to a certain extent (the temperature of the first high-temperature water vapor obtained after the first stage heat exchange is 250 ℃~400 ℃, and the temperature of the carbon dioxide discharged from the regeneration oxidation unit is 700 ℃~850 ℃).

[0029] See Figure 1 In this embodiment, the gas purification unit receives the gaseous products discharged from the first heat exchange unit and purifies them to remove sulfur and nitrogen compounds and dust impurities, obtaining high-purity syngas. The fuel synthesis unit receives hydrogen and carbon monoxide discharged from the cathode of the SOEC electrolysis unit, as well as the high-purity syngas discharged from the gas purification unit, as raw materials for the synthesis of green fuels. This embodiment controls the hydrogen-to-carbon ratio (generally controlled between 1.8 and 4.0) of the hydrogen and carbon monoxide discharged from the cathode of the SOEC electrolysis unit by adjusting the amount of water vapor introduced into the SOEC electrolysis unit. Furthermore, the mixing ratio of the hydrogen and carbon monoxide discharged from the cathode of the SOEC electrolysis unit to the high-purity syngas discharged from the gas purification unit is flexibly adjusted according to the type of green fuel being prepared, ensuring that the hydrogen-to-carbon ratio of the resulting syngas meets the requirements for direct use in the subsequent synthesis of green fuels.

[0030] This invention organically integrates core functional units such as biomass gasification, in-situ CO2 capture, high-temperature co-electrolysis of SOEC, and fuel synthesis by coupling a biomass gasification unit with a solid oxide electrolyzer (SOEC) co-electrolysis unit, forming a closed-loop material and energy cycle system. The heat generated by biomass gasification is used to preheat the steam required for electrolysis, the oxygen generated by SOEC electrolysis is used for the regeneration of gasifying agents and functional materials, and the CO2 generated by gasification is captured and used for co-electrolysis. By precisely adjusting the amount of steam input to the SOEC electrolysis unit, the H2 / CO ratio generated by SOEC co-electrolysis can be flexibly controlled. After mixing with the syngas generated by gasification, the optimal hydrogen-carbon ratio required for downstream green fuel synthesis can be directly obtained, eliminating the expensive and energy-intensive water-gas shift (WGS) process in traditional processes, avoiding additional CO2 and carbon losses caused by adjusting the hydrogen-carbon ratio, significantly improving the overall energy efficiency of the system, and maximizing the utilization of carbon, hydrogen, and oxygen elements.

[0031] In another embodiment of the present invention, the system further includes: a second heat exchange unit and a third heat exchange unit; the second heat exchange unit is connected to the first heat exchange unit and the gas purification unit respectively, and is used to perform a second-stage heat exchange between the gaseous product discharged from the first heat exchange unit and pure water to obtain a second high-temperature water vapor; the gaseous product after heat exchange and cooling is supplied to the gas purification unit for purification; the third heat exchange unit is connected to the second heat exchange unit, the SOEC electrolysis unit and the gasification unit respectively, and is used to perform a heat exchange between the second high-temperature water vapor discharged from the second heat exchange unit and another part of high-temperature oxygen discharged from the anode of the SOEC electrolysis unit, and the obtained third high-temperature water vapor is supplied to the SOEC electrolysis unit for co-electrolysis, and the oxygen after heat exchange is introduced into the gasification unit as a gasifying agent to participate in the reaction.

[0032] See Figure 2 A second heat exchange unit is installed after the first heat exchange unit. It utilizes the residual heat of the pre-cooled gaseous products to generate medium-temperature steam (second high-temperature steam), achieving cascaded utilization of the sensible heat of the gasification products and maximizing thermal energy utilization. Furthermore, a third heat exchange unit uses the high-temperature oxygen (approximately 650℃~850℃) discharged from the SOEC anode to heat the medium-temperature steam generated in the second heat exchange unit, further raising its temperature. The resulting third high-temperature steam (approximately 500℃~700℃) is close to the high temperature required for SOEC electrolysis. Simultaneously, the oxygen cooled after heat exchange (550℃~750℃) is introduced into the gasification unit as a gasifying agent, its temperature precisely meeting the requirements for autothermal or endothermic gasification reactions. This design ensures efficient operation of the SOEC and provides a suitable temperature gasifying agent for the gasification unit, achieving thermal coupling between units.

[0033] In another embodiment of the present invention, the system further includes: a fourth heat exchange unit; the fourth heat exchange unit is connected to the SOEC electrolysis unit and the fuel synthesis unit respectively, and is used to exchange heat between the hydrogen and carbon monoxide gas discharged from the cathode of the SOEC electrolysis unit and pure water, so that the obtained high-temperature water vapor is used for co-electrolysis in the SOEC electrolysis unit, and the cooled hydrogen and carbon monoxide gas is used for the fuel synthesis unit to synthesize green fuel.

[0034] See Figure 3 The H2 / CO mixture at the cathode outlet of the SOEC electrolysis unit reaches temperatures as high as 650℃~850℃. The fourth heat exchange unit utilizes the waste heat from this high-temperature product to preheat pure water, generating high-temperature steam which is then supplied back to the SOEC electrolysis unit, further reducing the external heat load and power consumption required for electrolysis. By cooling the H2 / CO mixture to 400℃~500℃ through heat exchange to match the temperature requirements for green fuel synthesis, additional cooling or preheating equipment in downstream sections is eliminated, achieving precise connection of process parameters.

[0035] In a second aspect, the present invention provides a process for producing green fuel through biomass gasification coupled with SOEC co-electrolysis, the process being applicable to the biomass gasification coupled with SOEC co-electrolysis system for producing syngas described in the first aspect above, comprising: In the gasification unit, the biomass feedstock undergoes a gasification reaction under the synergistic effect of functional materials, water vapor, and oxygen to obtain high-temperature gaseous products containing CO, H2, and CO2. Some of the generated CO2 is captured by the functional materials. The high-temperature gaseous product undergoes a first-stage heat exchange with pure water in the first heat exchange unit to obtain first high-temperature water vapor, and a portion of the first high-temperature water vapor is consumed by the gasification reaction. The remaining first high-temperature water vapor is co-electrolyzed with carbon dioxide in the SOEC electrolysis unit. High-temperature oxygen is obtained at the anode end of the SOEC electrolysis unit, and hydrogen and carbon monoxide are obtained at the cathode end. Part of the high-temperature oxygen is consumed by the gasification reaction. The solid material discharged from the gasification unit is regenerated in the regeneration oxidation unit under the action of oxygen to regenerate functional materials and release the captured carbon dioxide. The carbon dioxide is used for co-electrolysis in the SOEC electrolysis unit, and the oxygen is provided by the anode of the SOEC electrolysis unit. The gaseous products after the first stage of heat exchange are purified in the gas purification unit to remove sulfur and nitrogen compounds and dust impurities. The resulting high-purity syngas is used for the synthesis of green fuels. In specific implementation, under the synergistic effect of functional materials, water vapor, and oxygen, biomass feedstock undergoes gasification and is converted into high-temperature gaseous products containing CO, H2, and CO2. The functional materials include oxygen-carrying functional materials and carbon dioxide capture functional materials. The oxygen-carrying functional material provides lattice oxygen for biomass gasification under gasification reaction conditions, partially oxidizing it to CO and H2, and is itself reduced. The reduced oxygen-carrying functional material can be recycled under high-temperature, oxygen-rich conditions. The oxygen-carrying functional material participates in the biomass feedstock gasification reaction and can adjust the hydrogen-to-carbon ratio in the resulting gaseous products. In this embodiment, the oxygen-carrying functional material can be selected from Fe2O3, Fe3O4, Mn2O3, Mn3O4, MnFe2O4, or Fe2O3@ZrO2. The carbon dioxide capture functional material is used to capture the generated carbon dioxide and can be recycled under high-temperature conditions, releasing the captured carbon dioxide. In this embodiment, the carbon dioxide capture functional material can be selected from CaO and CaO. MgO, CaO Al2O3, Li2ZrO3 or Li4SiO4; the gasification process is carried out at 800 ℃~1300 ℃ for the gasification conversion of biomass feedstock; In practice, the gasification conversion takes place in the gasification unit. The input materials include: biomass feedstock, O2 (provided by the SOEC electrolysis unit of this system), steam (provided by the first heat exchange unit), and functional materials (including oxygen-carrying functional materials and carbon dioxide capture functional materials; such as Fe2O3 / Fe3O4 and CaO). The output materials include: high-temperature gaseous products containing CO, H2, and CO2, and solid-phase materials composed of deactivated functional materials and ash. The oxygen-carrying functional materials, such as Fe2O3 / Fe3O4, provide lattice oxygen, partially oxidizing the biomass to CO and H2, while being reduced to Fe / FeO. This helps increase the proportion of carbon monoxide and hydrogen in the gasification conversion products. The CO2 in the gaseous products is captured by the carbon dioxide capture functional material CaO to form CaCO3. The temperature of the high-temperature gaseous products output from the gasification unit is between 750 ℃ ​​and 1100 ℃.

[0036] In specific implementation, the first-stage heat exchange takes place in the first heat exchange unit. The first-stage heat exchange allows the high-temperature gaseous product to exchange heat with pure water, and the pure water absorbs heat to form the first high-temperature steam. The first-stage heat exchange effectively utilizes the waste heat of the high-temperature gaseous product (approximately 750 ℃~1100 ℃) to produce steam at 250 ℃~400 ℃. The steam outlet is divided into two paths: one path is fed back to the gasification unit for the gasification conversion of biomass raw materials, and the other path is connected to the SOEC electrolysis unit to be used as the feedstock for electrolysis in the SOEC electrolysis unit. After the high-temperature gaseous product undergoes heat exchange, the temperature drops to 250 ℃~350 ℃.

[0037] In practice, the regeneration of functional materials takes place in the regeneration oxidation unit. This unit receives solid material discharged from the gasification unit and some high-temperature oxygen discharged from the anode of the SOEC electrolysis unit, oxidizing and regenerating the functional materials and releasing carbon dioxide. The regeneration oxidation unit relies on the high-temperature O2 (approximately 650℃~850℃) discharged from the anode of the SOEC electrolysis unit and the solid material (750℃~1100℃) from the gasifier for heat. Carbon dioxide-capturing functional materials, such as CaO, capture CO2 to generate CaCO3, which then decomposes at high temperature in the regeneration oxidation unit, releasing CO2. The oxygen-carrying functional materials reduced in the gasifier are oxidized to Fe2O3 / Fe3O4 by oxygen in the regeneration oxidation unit. The heat released during this reaction further supplements the heat required for the regeneration of the carbon dioxide-capturing functional materials. This exothermic reaction helps maintain the reactor temperature, and the entire regeneration oxidation unit requires no additional energy supply. The regenerated functional materials are recycled back to the gasification unit for secondary utilization; the released high-concentration, high-purity CO2 gas is supplied to the SOEC electrolysis unit for co-electrolysis.

[0038] In practice, the SOEC electrolysis unit co-electrolyzes the first high-temperature steam received and the carbon dioxide discharged from the regeneration oxidation unit, obtaining high-temperature oxygen at the anode and hydrogen and carbon monoxide at the cathode. The SOEC electrolysis unit uses green electricity such as wind power and photovoltaic power to supply power to the SOEC stack, so that the co-electrolysis operating temperature of the SOEC electrolysis unit is 700℃~900℃. Furthermore, due to the heat carried by the co-electrolysis objects themselves, the consumption of green electricity by the SOEC electrolysis unit is reduced to a certain extent (the temperature of the first high-temperature steam obtained after the first stage heat exchange is 250℃~400℃, and the temperature of the carbon dioxide discharged from the regeneration oxidation unit is 700℃~850℃).

[0039] In practice, the gas purification unit purifies the gaseous products discharged from the first heat exchange unit to remove sulfur and nitrogen compounds and dust impurities, thereby obtaining high-purity syngas. The fuel synthesis unit uses hydrogen and carbon monoxide discharged from the cathode of the SOEC electrolysis unit and high-purity syngas discharged from the gas purification unit as raw materials. By flexibly adjusting the mixing ratio of the two, the hydrogen-to-carbon ratio of the syngas obtained after mixing meets the requirements for subsequent green fuel synthesis.

[0040] This invention organically integrates core functional units such as biomass gasification, in-situ CO2 capture, high-temperature co-electrolysis of SOEC, and fuel synthesis by coupling a biomass gasification unit with a solid oxide electrolyzer (SOEC) co-electrolysis unit, forming a closed-loop material and energy cycle system. The heat generated by biomass gasification is used to preheat the steam required for electrolysis, the oxygen generated by SOEC electrolysis is used for the regeneration of gasifying agents and functional materials, and the CO2 generated by gasification is captured and used for co-electrolysis. By precisely adjusting the amount of steam input to the SOEC electrolysis unit, the H2 / CO ratio generated by SOEC co-electrolysis can be flexibly controlled. After mixing with the syngas generated by gasification, the optimal hydrogen-carbon ratio required for downstream green fuel synthesis can be directly obtained, eliminating the expensive and energy-intensive water-gas shift (WGS) process in traditional processes, avoiding additional CO2 and carbon losses caused by adjusting the hydrogen-carbon ratio, significantly improving the overall energy efficiency of the system, and maximizing the utilization of carbon, hydrogen, and oxygen elements.

[0041] In some embodiments, the temperature of the gaseous product after the first-stage heat exchange is 250 ℃ to 350 ℃, and the temperature of the first high-temperature steam produced is 250 ℃ to 400 ℃.

[0042] In some embodiments, before the gaseous products after the first-stage heat exchange are purified in the gas purification unit, the process further includes: The gaseous product undergoes a second-stage heat exchange with pure water in the second heat exchange unit to obtain a second high-temperature water vapor. After the second-stage heat exchange, a gaseous product close to room temperature is obtained for purification by the gas purification unit. The second high-temperature steam exchanges heat with a portion of the high-temperature oxygen obtained at the anode of the SOEC electrolysis unit in the third heat exchange unit. The second high-temperature steam is further heated, and the resulting third high-temperature steam is supplied to the SOEC electrolysis unit for co-electrolysis. The oxygen cooled down after heat exchange is used as a gasifying agent to participate in the gasification reaction of biomass raw materials.

[0043] In practice, after the first-stage heat exchange, the pre-cooled gaseous products undergo secondary heat recovery in the second heat exchange unit to generate medium-temperature steam (secondary high-temperature steam), achieving cascaded utilization of the sensible heat of the gasification products and maximizing thermal energy utilization. Furthermore, the high-temperature oxygen (approximately 650℃~850℃) discharged from the SOEC anode is used to heat the medium-temperature steam generated in the second heat exchange unit, further raising its temperature to a secondary high-temperature steam (approximately 500℃~700℃), whose temperature is close to the high temperature required for SOEC electrolysis. Simultaneously, the cooled oxygen (550℃~750℃) after heat exchange is introduced into the gasification unit as a gasifying agent, its temperature precisely meeting the requirements for autothermal or endothermic gasification reactions. This design ensures efficient SOEC operation and provides a suitable temperature gasifying agent for the gasification unit, achieving thermal coupling between units.

[0044] In some embodiments, the temperature of the gaseous product after the second-stage heat exchange is 25 ℃ to 45 ℃, the temperature of the second high-temperature steam is 150 ℃ to 170 ℃, the temperature of the third high-temperature steam is 500 ℃ to 700 ℃, and the temperature of the oxygen after heat exchange and cooling is 550 ℃ to 750 ℃.

[0045] In some embodiments, the process further includes: The hydrogen and carbon monoxide gas discharged from the cathode of the SOEC electrolysis unit exchange heat with pure water in the fourth heat exchange unit. The high-temperature steam formed by the heating of the pure water is used for co-electrolysis in the SOEC electrolysis unit, and the cooled hydrogen and carbon monoxide gas is used to synthesize green fuel in the fuel synthesis unit.

[0046] In practice, the temperature of the H2 / CO mixture at the cathode outlet of the SOEC electrolysis unit reaches as high as 650 ℃~850 ℃. The fourth heat exchange unit utilizes the waste heat of this high-temperature product to preheat pure water, generating high-temperature steam which is then supplied back to the SOEC electrolysis unit, further reducing the external heat load and power consumption required for electrolysis. By cooling the H2 / CO mixture to 400 ℃~500 ℃ through heat exchange, the temperature of the H2 / CO mixture is matched to the temperature requirements of the methanol or methane synthesis catalyst, preventing the downstream synthesis catalyst from undergoing rapid sintering and deactivation due to excessively high inlet temperature. At the same time, it eliminates the need for additional cooling or preheating equipment in the downstream section, achieving precise connection of process parameters.

[0047] In some embodiments, the components of the high-purity syngas obtained by the purification process are distributed as follows: H2: 40%–45%; CO: 35%–45%; CO2: 5%–10%; CH4: <1%; Sulfides: <0.1 ppm; Compared with the traditional biomass feedstock gasification to produce syngas, the high-purity syngas obtained in this embodiment has a higher hydrogen-to-carbon ratio; the ideal hydrogen-to-carbon ratio required for green fuel synthesis can be easily obtained by simply adjusting the amount of water vapor electrolysis; the water-gas conversion process is eliminated.

[0048] To enable those skilled in the art to more clearly understand the present invention, the following embodiments will be used to provide a detailed description of the system and process for producing syngas by coupling biomass gasification with SOEC co-electrolysis.

[0049] Example 1 See Figure 4 The diagram shown illustrates the energy cascade utilization and material flow of a biomass gasification coupled with SOEC co-electrolysis process for fuel production. This process includes the following steps: (1) Biomass feedstock gasification: Crushed and dried agricultural and forestry waste biomass feedstock (particle size: 0.1-0.5 mm, moisture content: ≤5 wt%) is co-input into the gasification furnace (gasification unit) along with oxygen-carrying functional materials and carbon dioxide capture functional materials (Fe2O3:CaO=1:2). The functional materials are fed in separate zones, with CaO distributed in the edge zone at 600 ℃-700 ℃ and Fe2O3 distributed in the core gasification zone at 800 ℃-1000 ℃. The gasification reaction is carried out under high temperature conditions (reaction temperature: 800 ℃-1300 ℃; operating pressure: atmospheric pressure to 2 MPa). The oxygen-carrying functional material Fe2O3 provides lattice oxygen, which oxidizes part of the biomass into CO and H2, and is itself reduced to Fe / FeO. After the reaction, a high-temperature gaseous product containing CO, H2 and CO2 is obtained (750 ℃-1100 ℃, main components and proportions: H2O: 25%-35%). H2: 20%~40%, CO: 25%~40%, CO2: 5%~10%, CH4: <2%, others (sulfides, etc.): <1%); The carbon dioxide capture functional material CaO adsorbs and vaporizes CO2 to generate CaCO3, thus achieving directional capture of CO2.

[0050] (2) First stage heat exchange: The high-temperature gaseous products in the gasifier are discharged to heat exchanger 1 (first heat exchange unit). After the first stage heat exchange with pure water, the first high-temperature water vapor (250 ℃~400 ℃) is introduced into the gasifier as part of the gasification agent. The remaining solid materials in the gasifier (including reduced oxygen-carrying functional materials, saturated carbon dioxide capture functional materials and ash) are transported to the regeneration tower (regeneration oxidation unit).

[0051] (3) Functional material regeneration: The remaining solid material in the gasifier is sent to the regeneration tower (reaction temperature: 750 ℃~900℃, operating pressure: atmospheric pressure). The high-temperature oxygen of 650 ℃~850 ℃ discharged from the anode of the SOEC electrolysis unit serves as part of the heat source and is introduced together with the fluidizing medium to provide heat for carbonate decomposition. CaCO3 decomposes at high temperature, releasing CO2 with a purity >95%, and the reduced Fe is re-oxidized to Fe2O3, completing the oxidation regeneration of the functional material. The high-purity CO2 released during regeneration is pretreated and sent to the cathode of the SOEC electrolysis unit. The regenerated functional material is recycled back to the gasification unit (recovery rate: ≥95%).

[0052] (4) Cascade utilization of waste heat between materials: After the first stage of heat exchange, the high-temperature gaseous product is discharged to heat exchanger 2 and undergoes a second stage of heat exchange with pure water. The temperature of the gaseous product after heat exchange is close to room temperature. The generated second high-temperature water vapor (150 ℃~170 ℃) is introduced into heat exchanger 3 and continues to exchange heat with the high-temperature oxygen discharged from the anode of the SOEC electrolytic cell, so that the water vapor temperature is exchanged to 500 ℃~700 ℃. (5) SOEC co-electrolysis unit (SOEC electrolyzer): The high-temperature steam (500 ℃~700 ℃) output from heat exchanger 3 and the high-purity CO2 (700 ℃~850 ℃) produced by the regeneration oxidation unit are fed into the cathode of the SOEC electrolyzer (SOEC electrolysis unit) to supply power to the SOEC stack with green electricity such as wind power and photovoltaic power. At high temperature, a co-electrolysis reaction occurs to generate CO and H2 with a purity of 99.5%~99.9%. The high-temperature O2 (purity >99.9%) generated at the anode of the SOEC electrolyzer is flexibly controlled by adjusting the feed rate of the cathode steam to adjust the hydrogen-carbon ratio of the electrolytic synthesis gas.

[0053] (6) Gas purification: After heat exchange in two heat exchange units (≤40 ℃), the high-temperature gaseous products enter the purification tower (gas purification unit) to remove impurities such as sulfur and nitrogen compounds and dust, resulting in high-purity purified syngas (main components and proportions of syngas: H2: 40 %~45 %, CO: 35 %~45 %, CO2: 5 %~10 %, CH4: <1 %, sulfides: <0.1 ppm); at the same time, the hydrogen-carbon ratio of the electrolytic syngas produced at the cathode can be adjusted by controlling the amount of water vapor introduced into the SOEC electrolyzer, so that after the purified syngas and the electrolytic syngas are mixed, (8) Green fuel synthesis: Green methanol synthesis process: High-purity CO + H2 (>99.5%) from the cathode of the SOEC electrolysis unit exchanges heat with pure water in heat exchanger 4 (fourth heat exchange unit), where the temperatures of both steam and high-purity CO + H2 are between 400 ℃ and 500 ℃. The high-purity CO + H2 is then mixed with clean synthesis gas from the gas purification unit to obtain synthesis gas with an H2 / CO ratio adjusted to approximately 2.0. This gas is fed into a fixed-bed catalytic reactor, where a catalytic synthesis reaction occurs at 200 ℃–250 ℃, 5 MPa–10 MPa, and with a copper-based catalyst, producing crude methanol. The crude methanol then enters a multi-stage distillation system to remove light and heavy components and unreacted gases, ultimately yielding high-purity green methanol product with a purity ≥99.9%. Steam is supplied to the SOEC electrolysis unit for co-electrolysis.

[0054] The green methane synthesis process is as follows: High-purity CO + H2 (>99.5%) from the cathode of the SOEC electrolysis unit exchanges heat with pure water in heat exchanger 4 (the fourth heat exchange unit), where the temperatures of both the steam and the high-purity CO + H2 are between 400 ℃ and 500 ℃. The high-purity CO + H2 is then mixed with clean syngas from the gas purification unit to obtain syngas with an H2 / CO ratio adjusted to approximately 3.0. This syngas is then fed into a fixed-bed methanation reactor, where a catalytic methanation reaction occurs at 280–400 ℃, 3–5 MPa, and with a nickel-based catalyst, producing crude methane. The crude methane is then purified in a low-temperature liquefaction reactor to obtain liquefied green methane product with a purity ≥98%. Steam is supplied to the SOEC electrolysis unit for co-electrolysis.

[0055] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. In addition, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0056] For the sake of simplicity, the method embodiments are described as a series of actions. However, those skilled in the art should understand that the present invention is not limited to the described order of actions, as some steps can be performed in other orders or simultaneously according to the present invention. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and components involved are not necessarily essential to the present invention.

[0057] The above provides a detailed description of the system and process for producing green fuels by biomass gasification coupled with SOEC co-electrolysis. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only intended to help understand the method and core ideas of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A system for producing green fuel by biomass gasification coupled with SOEC co-electrolysis, characterized in that, include: Gasification unit, first heat exchange unit, gas purification unit, regeneration oxidation unit, SOEC electrolysis unit and fuel synthesis unit; The gasification unit is used to convert biomass raw materials into high-temperature gaseous products containing CO, H2 and CO2 through a gasification reaction under the synergistic effect of functional materials, water vapor and oxygen. Some of the functional materials are used to capture the generated carbon dioxide, and some of the functional materials are used to adjust the hydrogen-carbon ratio in the obtained gaseous products. The first heat exchange unit is connected to the gasification unit and is used to perform a first-stage heat exchange between the high-temperature gaseous product and pure water. After absorbing heat, the pure water forms first high-temperature water vapor and a portion of the first high-temperature water vapor is returned to the gasification unit for the biomass raw material to undergo a gasification reaction. The regeneration oxidation unit is connected to the gasification unit and the SOEC electrolysis unit respectively, and is used to receive the solid material discharged from the gasification unit and part of the high-temperature oxygen discharged from the anode of the SOEC electrolysis unit to regenerate the functional material and release carbon dioxide. The SOEC electrolysis unit is connected to the first heat exchange unit and is used to receive the remaining first high-temperature water vapor and the carbon dioxide discharged from the regeneration oxidation unit for co-electrolysis, so as to obtain high-temperature oxygen at the anode and hydrogen and carbon monoxide at the cathode. The gas purification unit is connected to the first heat exchange unit and is used to receive the gaseous products discharged from the first heat exchange unit and perform purification treatment to remove sulfur and nitrogen compounds and dust impurities to obtain high-purity syngas. The fuel synthesis unit is connected to the gas purification unit and the SOEC electrolysis unit, and is used to receive hydrogen and carbon monoxide discharged from the cathode of the SOEC electrolysis unit, as well as high-purity synthesis gas discharged from the gas purification unit, as raw materials for the synthesis of green fuel.

2. The system for producing green fuel by biomass gasification coupled with SOEC co-electrolysis according to claim 1, characterized in that, Also includes: The second heat exchange unit and the third heat exchange unit; The second heat exchange unit is connected to the first heat exchange unit and the gas purification unit respectively, and is used to enable the gaseous products discharged from the first heat exchange unit to exchange heat with pure water in the second stage to obtain second high-temperature water vapor; the gaseous products after heat exchange and cooling are supplied to the gas purification unit for purification. The third heat exchange unit is connected to the second heat exchange unit, the SOEC electrolysis unit and the gasification unit respectively. It is used to exchange heat between the second high-temperature water vapor discharged from the second heat exchange unit and another part of the high-temperature oxygen discharged from the anode of the SOEC electrolysis unit. The obtained third high-temperature water vapor is used for co-electrolysis in the SOEC electrolysis unit. The oxygen after heat exchange is introduced into the gasification unit as a gasifying agent to participate in the reaction.

3. The system for producing green fuel by biomass gasification coupled with SOEC co-electrolysis according to claim 1, characterized in that, Also includes: Fourth heat exchange unit; The fourth heat exchange unit is connected to the SOEC electrolysis unit and the fuel synthesis unit respectively. It is used to exchange heat between the hydrogen and carbon monoxide gas discharged from the cathode of the SOEC electrolysis unit and pure water. The resulting high-temperature steam is used for co-electrolysis in the SOEC electrolysis unit, and the cooled hydrogen and carbon monoxide gas is used for the fuel synthesis unit to synthesize green fuel.

4. A system for producing green fuel by biomass gasification coupled with SOEC co-electrolysis, characterized in that, A system for producing fuel from biomass through gasification coupled with SOEC co-electrolysis as described in any one of claims 1 to 3, comprising: In the gasification unit, the biomass feedstock undergoes a gasification reaction under the synergistic effect of functional materials, water vapor, and oxygen to obtain high-temperature gaseous products containing CO, H2, and CO2. Some of the generated CO2 is captured by the functional materials. The high-temperature gaseous product undergoes a first-stage heat exchange with pure water in the first heat exchange unit to obtain first high-temperature water vapor, and a portion of the first high-temperature water vapor is consumed by the gasification reaction. The remaining first high-temperature water vapor is co-electrolyzed with carbon dioxide in the SOEC electrolysis unit. High-temperature oxygen is obtained at the anode end of the SOEC electrolysis unit, and hydrogen and carbon monoxide are obtained at the cathode end. Part of the high-temperature oxygen is consumed by the gasification reaction. The solid material discharged from the gasification unit is regenerated in the regeneration oxidation unit under the action of oxygen to regenerate functional materials and release the captured carbon dioxide. The carbon dioxide is used for co-electrolysis in the SOEC electrolysis unit, and the oxygen is provided by the anode of the SOEC electrolysis unit. The gaseous products after the first stage of heat exchange are purified in the gas purification unit to remove sulfur and nitrogen compounds and dust impurities. The resulting high-purity syngas is used for the synthesis of green fuels. The functional materials include oxygen-carrying functional materials and carbon dioxide-capturing functional materials. The oxygen-carrying functional materials are selected from Fe2O3, Fe3O4, Mn2O3, Mn3O4, MnFe2O4, or Fe2O3@ZrO2; the carbon dioxide-capturing functional materials are selected from CaO, CaO, and CaO. MgO, CaO Al2O3, Li2ZrO3 or Li4SiO4.

5. The process for producing green fuel by biomass gasification coupled with SOEC co-electrolysis according to claim 4, characterized in that, The temperature of the gaseous product after the first stage heat exchange is 250 ℃~350 ℃, and the temperature of the first high-temperature water vapor is 250 ℃~400 ℃.

6. The process for producing fuel by biomass gasification coupled with SOEC co-electrolysis according to claim 4, characterized in that, Before the gaseous products after the first-stage heat exchange are purified in the gas purification unit, the process further includes: The gaseous product undergoes a second-stage heat exchange with pure water in the second heat exchange unit to obtain a second high-temperature water vapor. After the second-stage heat exchange, a gaseous product close to room temperature is obtained for purification by the gas purification unit. The second high-temperature steam exchanges heat with a portion of the high-temperature oxygen obtained at the anode of the SOEC electrolysis unit in the third heat exchange unit. The second high-temperature steam is further heated, and the resulting third high-temperature steam is supplied to the SOEC electrolysis unit for co-electrolysis. The oxygen cooled down after heat exchange is used as a gasifying agent to participate in the gasification reaction of biomass raw materials.

7. The process for producing green fuel by biomass gasification coupled with SOEC co-electrolysis according to claim 6, characterized in that, The temperature of the gaseous products after the second-stage heat exchange is 25 ℃~45 ℃, and the temperature of the second high-temperature water vapor is 150 ℃~170 ℃; The temperature of the third high-temperature steam is 500 ℃~700 ℃, and the temperature of the oxygen after heat exchange and cooling is 550 ℃~750 ℃.

8. The process for producing green fuel by biomass gasification coupled with SOEC co-electrolysis according to claim 4, characterized in that, The process also includes: The hydrogen and carbon monoxide gas discharged from the cathode of the SOEC electrolysis unit exchange heat with pure water in the fourth heat exchange unit. The high-temperature steam formed by the heating of the pure water is used for co-electrolysis in the SOEC electrolysis unit, and the cooled hydrogen and carbon monoxide gas is used to synthesize green fuel in the fuel synthesis unit.

9. The process for producing green fuel by biomass gasification coupled with SOEC co-electrolysis according to claim 8, characterized in that, The temperature of the fourth high-temperature water vapor is 400 ℃~500 ℃, and the temperature of the cooled hydrogen and carbon monoxide gases is 400 ℃~500 ℃.

10. The process for producing green fuel by biomass gasification coupled with SOEC co-electrolysis according to claim 4, characterized in that, The composition of the high-purity syngas obtained by the purification process is as follows: H2:40 %～45 %； CO: 35%~45%; CO2: 5%~10%; CH4:<1%; Sulfide: <0.1 ppm.

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