A system for coupling biomass fluidized bed gasification and green hydrogen to produce green methanol synthesis gas

Abstract

The present application belongs to the technical field of biomass gasification, and particularly relates to a system for producing green methanol synthesis gas by coupling biomass fluidized bed gasification with green hydrogen, which comprises a biomass gasification unit, wherein the biomass gasification unit is connected with a waste heat recovery and dust washing purification unit, the waste heat recovery and dust washing purification unit is connected with a partial oxidation unit, the partial oxidation unit is connected with a decarburization unit, the decarburization unit is connected with a gas mixing storage tank, the carbon dioxide separated from the decarburization unit is reflowed back to the biomass gasification unit, the hydrogen gas inlet of the gas mixing storage tank is connected with the hydrogen gas outlet of an electrolytic water unit through a pipeline, and the hydrogen gas outlet of the electrolytic water unit is connected with the hydrogen gas inlets of the biomass gasification unit and the partial oxidation unit through pipelines. Through reasonable allocation of hydrogen gas, the energy flow in the process is optimized, the problem of unreasonable energy and material circulation in the existing process is solved, and the yield and economy of green methanol synthesis gas are significantly improved.

Description

Technical Field

[0001] This invention belongs to the field of biomass gasification technology, specifically relating to a system for biomass fluidized bed gasification coupled with green hydrogen to produce green methanol synthesis gas. Background Technology

[0002] Green methanol is a type of methanol produced from renewable resources. Its production process is characterized by low carbon emissions and environmental friendliness, aligning with global energy transition and carbon neutrality goals. Unlike traditional methanol production methods, green methanol production typically relies on clean energy sources such as biomass, green hydrogen, or carbon dioxide capture and utilization. Furthermore, methanol, as an important chemical feedstock, can be used to synthesize fuels and chemicals, as well as for energy carrier applications, possessing significant economic and environmental value. Currently, green methanol production faces challenges such as low yield, high cost, and low energy efficiency. Therefore, improving the yield of green methanol syngas, optimizing energy efficiency, and reducing production costs are key directions for future technological development.

[0003] Biomass gasification is the process of converting solid biomass into combustible gas through heating and gasification reactions. Fluidized bed gasification technology, as one of the mature methods of biomass gasification, utilizes a fluidized bed gasifier to effectively maintain sufficient contact between biomass particles and the gasifying agent, promoting the gasification reaction. Compared to fixed bed gasification and entrained gasification, it has stronger feedstock adaptability, simpler feedstock and gas processing characteristics, and higher economic efficiency, making it suitable for large-scale industrial biomass gasification. Despite the significant advantages of fluidized bed gasification technology, some technical bottlenecks and challenges still exist in the preparation of green methanol syngas.

[0004] Patent CN 118064185 A discloses a system for producing green methanol from biomass gasification. This system consists of a biomass gasification unit, a compression unit, and a methanol synthesis unit connected in sequence. Biomass enters the gasification unit through a feeding device and is fully gasified to obtain syngas. The syngas then passes through a cracking unit, a waste heat recovery unit, and a dust removal unit before being compressed and synthesized into green methanol. This system boasts advantages such as good environmental performance, high energy efficiency, high continuous operation rate, wide load adjustment range, convenient start-up and shutdown, high automation, and safety and reliability. However, it does not effectively separate and utilize carbon dioxide from the syngas. Carbon dioxide, as a feedstock for methanol synthesis, has high energy consumption and a slow reaction rate. In contrast, carbon monoxide is a more mature and efficient feedstock for methanol synthesis.

[0005] Patent CN 116814300 A discloses a high-efficiency biomass gasification system for producing green methanol. This system includes: a solar and wind power generation and water electrolysis subsystem, a biomass gasification subsystem, a syngas shift conversion subsystem, and a methanol synthesis subsystem. Oxygen generated by the solar and wind power generation and water electrolysis subsystem serves as the gasification medium in the biomass gasification subsystem, synthesizing high-calorific-value biomass syngas. The biomass syngas, after passing through the syngas shift conversion subsystem, is then fed into the methanol synthesis subsystem to synthesize methanol. This invention is a green, environmentally friendly, and energy-saving system, consuming only renewable energy. The system's products, "green hydrogen" and "green methanol," are both green products. The production process is characterized by low pollution and low energy consumption, fully embodying the concepts of sustainable development and emission reduction. However, the carbon dioxide generated during the gasification process is not effectively recycled. A large amount of carbon dioxide participates in methanol synthesis, resulting in increased energy consumption, leading to resource waste and increased carbon dioxide emissions. Furthermore, the supply and demand of hydrogen are not balanced; the amount of hydrogen produced is mismatched with the amount required for the gasification reaction and green methanol synthesis, resulting in additional energy consumption. Summary of the Invention

[0006] This invention addresses the problems of low production efficiency caused by unbalanced hydrogen usage and inadequate carbon dioxide treatment by providing a system for producing green methanol synthesis gas by coupling biomass fluidized bed gasification with green hydrogen.

[0007] To achieve the above objectives, the present invention employs the following technical solution:

[0008] A system for producing green methanol syngas from biomass via fluidized bed gasification coupled with green hydrogen includes a biomass gasification unit. This unit employs pressurized fluidized bed gasification technology to suspend biomass feedstock in a fluidized bed and allow it to fully contact a gasifying agent for gasification to produce syngas. The feedstock gas outlet of the biomass gasification unit is connected via a pipeline to the feedstock gas inlet of a waste heat recovery and dust removal / washing purification unit. The waste heat recovery and dust removal / washing purification unit performs waste heat recovery and purification treatment on the feedstock gas. The feedstock gas outlet of this unit is connected via a pipeline to the feedstock gas inlet of a partial oxidation unit. The partial oxidation unit performs a partial oxidation reaction on the feedstock gas to generate low-methane syngas. The low-methane syngas outlet of the partial oxidation unit is connected via a pipeline to the low-methane syngas outlet of a decarbonization unit. The methane synthesis gas inlet and the outlet of the decarbonization unit are connected to a gas storage tank via a pipeline. The carbon dioxide separated by the decarbonization unit flows back to the biomass gasification unit. The hydrogen inlet of the gas storage tank is connected to the hydrogen outlet of the water electrolysis unit via a pipeline. The hydrogen is mixed with the purified synthesis gas produced by the decarbonization unit to form green methanol synthesis gas. The hydrogen outlet of the water electrolysis unit is also connected to the hydrogen inlets of the biomass gasification unit and the partial oxidation unit via pipelines. The oxygen outlet of the water electrolysis unit is connected to the oxygen inlets of the biomass gasification unit and the partial oxidation unit via pipelines. The steam outlet of the waste heat recovery and dust removal water washing purification unit and the steam outlet of the partial oxidation unit are both connected to the water vapor inlet of the biomass gasification unit via pipelines.

[0009] Furthermore, the water electrolysis unit includes an electrolysis cell, which is provided with a hydrogen outlet and an oxygen outlet. The hydrogen outlet of the electrolysis cell is connected to the hydrogen inlet of the biomass gasification unit, the partial oxidation unit and the gas mixing tank through pipes, respectively. The oxygen outlet of the electrolysis cell is connected to the oxygen inlet of the biomass gasification unit and the partial oxidation unit through pipes, respectively.

[0010] Furthermore, the biomass gasification unit includes a fluidized bed gasifier. The hydrogen inlet at the upper end of the fluidized bed gasifier is connected to the hydrogen inlet of the electrolytic cell via a pipeline. The raw material gas outlet of the fluidized bed gasifier is connected to the raw material gas inlet of the waste heat recovery and dust removal water washing purification unit via a pipeline. The oxygen inlet of the fluidized bed gasifier is connected to the oxygen outlet of the electrolytic cell via a pipeline. The steam inlet of the fluidized bed gasifier is connected to the steam outlets of the waste heat recovery and dust removal water washing purification unit and the partial oxidation unit via pipelines. The carbon dioxide inlet of the fluidized bed gasifier is connected to the carbon dioxide outlet of the decarbonization unit via a pipeline.

[0011] Furthermore, the waste heat recovery and dust removal washing purification unit includes a No. 1 waste heat recovery unit. The air inlet of the No. 1 waste heat recovery unit is connected to the raw material gas outlet of the fluidized bed gasifier via a pipeline. The steam outlet of the No. 1 waste heat recovery unit is connected to the steam inlet of the fluidized bed gasifier via a pipeline. The air outlet of the No. 1 waste heat recovery unit is connected to the air inlet of the cyclone separator via a pipeline. The air outlet of the cyclone separator is connected to the air inlet of the No. 1 washing tower via a pipeline. The raw material gas outlet of the No. 1 washing tower is connected to the raw material gas inlet of the partial oxidation unit via a pipeline.

[0012] Furthermore, the partial oxidation unit includes a gas integration box. The oxygen inlet of the gas integration box is connected to the oxygen outlet of the electrolytic cell via a pipeline. The raw material gas inlet of the gas integration box is connected to the raw material gas outlet of the No. 1 water scrubbing tower via a pipeline. The raw material gas outlet of the gas integration box is connected to the inlet of the POX furnace via a pipeline. The POX furnace has a hydrogen inlet in the middle. The hydrogen inlet of the POX furnace is connected to the hydrogen outlet of the electrolytic cell via a pipeline. The outlet of the POX furnace is connected to the inlet of the No. 2 waste heat recovery unit via a pipeline. The steam outlet of the No. 2 waste heat recovery unit is connected to the steam inlet of the fluidized bed gasifier via a pipeline. The raw material gas outlet of the No. 2 waste heat recovery unit is connected to the inlet of the No. 2 water scrubbing tower via a pipeline. The outlet of the No. 2 water scrubbing tower is connected to the syngas inlet of the decarbonization unit via a pipeline.

[0013] Furthermore, the decarbonization unit includes a decarbonization device, the syngas inlet of which is connected to the outlet of the No. 2 water washing tower via a pipeline, the carbon dioxide outlet of which is connected to the carbon dioxide inlet of the fluidized bed gasifier via a pipeline, and the outlet of which is connected to a gas storage tank via a pipeline.

[0014] Furthermore, the decarbonization unit is any one of a physical adsorption decarbonization device, a chemical absorption decarbonization device, or a membrane separation decarbonization device.

[0015] Furthermore, the water electrolysis unit is powered by renewable energy to ensure the green and low-carbon characteristics of the system.

[0016] Compared with the prior art, the present invention has the following advantages:

[0017] 1. This invention divides hydrogen into three parts. The first part is transported to the biomass gasification unit and injected into the top of the fluidized bed gasifier to participate in the reverse water-gas shift reaction. This not only effectively reduces the temperature at the top of the gasifier but also partially converts carbon dioxide into carbon monoxide, optimizing the gas composition ratio to better suit the needs of methanol synthesis. The second part is transported to the partial oxidation unit and injected from the middle of the POX furnace. This cools the high-temperature gas and reduces the byproducts generated in the partial oxidation reaction of methane: carbon dioxide, aldehydes, and ketones, converting them into more valuable products: carbon monoxide and alcohols. The third part is transported to the gas mixing tank to further regulate the ratio of hydrogen to carbon monoxide, ensuring that the generated syngas meets the optimal process requirements for green methanol synthesis. By rationally allocating hydrogen, the energy flow in the process is optimized, solving the problem of unreasonable energy and material circulation in existing processes, and significantly improving the yield and economy of green methanol syngas.

[0018] 2. This invention recycles carbon dioxide, returning the carbon dioxide separated from the decarbonization unit as a circulating gas to the fluidized bed gasifier, replacing the water vapor and nitrogen commonly used in traditional fluidized bed processes as a gasifying agent or pressurizing gas. This design not only reduces energy consumption and improves the utilization rate of carbon dioxide, but also significantly reduces wastewater generated by steam condensation, thereby improving the overall thermal efficiency of the system and reducing environmental pollution.

[0019] 3. This invention uses renewable energy to power the water electrolysis unit, fully realizing a green and low-carbon energy supply mode; the reasonable control of gas ratio and the efficient cooperation of multi-unit coupling have constructed a green methanol synthesis gas production system with low energy consumption and high resource utilization; compared with the traditional methanol synthesis process, this system greatly reduces the dependence on fossil fuels, reduces the emission of waste gas and wastewater, and constructs a multi-element collaborative, green and low-carbon methanol synthesis gas preparation system, which is in line with the trend of green development in the modern chemical industry. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of the present invention;

[0021] Figure 2 This is a system flowchart of the present invention;

[0022] In the diagram, there is an electrolytic cell (1), a fluidized bed gasifier (2), a waste heat recovery unit (3), a cyclone separator (4), a water washing tower (5), a gas integration box (6), a POX furnace (7), a waste heat recovery unit (8), a water washing tower (9), a decarbonization device (10), and a gas mixing tank (11). Detailed Implementation

[0023] To further illustrate the technical solution of the present invention, the present invention will be further described below through embodiments.

[0024] like Figure 1 and Figure 2As shown, a system for producing green methanol synthesis gas from biomass via fluidized bed gasification coupled with green hydrogen includes a biomass gasification unit. This unit employs pressurized fluidized bed gasification technology to suspend biomass feedstock and allow it to fully contact a gasifying agent for gasification to produce synthesis feedstock gas. The feedstock gas outlet of the biomass gasification unit is connected via a pipeline to the feedstock gas inlet of a waste heat recovery and dust removal / washing purification unit. The biomass gasification unit includes a fluidized bed gasifier 2. The hydrogen inlet at the upper end of the fluidized bed gasifier 2 is connected via a pipeline to the hydrogen inlet of an electrolytic cell 1. The feedstock gas outlet of the fluidized bed gasifier 2 is connected via a pipeline to the feedstock gas inlet of the waste heat recovery and dust removal / washing purification unit. The oxygen inlet of the fluidized bed gasifier 2 is connected via a pipeline... The oxygen outlet of the electrolytic cell 1 is connected via a pipeline. The steam inlet of the fluidized bed gasifier 2 is connected via pipelines to the steam outlets of the waste heat recovery and dust removal water washing purification unit and the partial oxidation unit, respectively. The carbon dioxide inlet of the fluidized bed gasifier 2 is connected via a pipeline to the carbon dioxide outlet of the decarbonization unit. The waste heat recovery and dust removal water washing purification unit performs waste heat recovery and purification treatment on the raw material gas. The waste heat recovery and dust removal water washing purification unit includes a No. 1 waste heat recovery unit 3. The inlet of the No. 1 waste heat recovery unit 3 is connected via a pipeline to the raw material gas outlet of the fluidized bed gasifier 2. The steam outlet of the No. 1 waste heat recovery unit 3 is connected via a pipeline to the steam inlet of the fluidized bed gasifier 2. The outlet of the No. 1 waste heat recovery unit 3 is connected via a pipeline to the steam outlet of the fluidized bed gasifier 2. A pipeline connects to the inlet of cyclone separator 4, and the outlet of cyclone separator 4 is connected to the inlet of No. 1 water washing tower 5 via a pipeline. The raw material gas outlet of No. 1 water washing tower 5 is connected to the raw material gas inlet of the partial oxidation unit via a pipeline. The raw material gas outlet of the waste heat recovery and dust removal water washing purification unit is connected to the raw material gas inlet of the partial oxidation unit via a pipeline. The partial oxidation unit includes a gas integration box 6. The hydrogen inlet of the gas integration box 6 is connected to the hydrogen outlet of electrolytic cell 1 via a pipeline. The oxygen inlet of the gas integration box 6 is connected to the oxygen outlet of electrolytic cell 1 via a pipeline. The raw material gas inlet of the gas integration box 6 is connected to the raw material gas outlet of No. 1 water washing tower 5 via a pipeline. The raw material gas inlet of the gas integration box 6 is connected to the raw material gas outlet of No. 1 water washing tower 5 via a pipeline. The feed gas outlet is connected to the inlet of POX furnace 7 via a pipeline. The outlet of POX furnace 7 is connected to the inlet of waste heat recovery unit 8 via a pipeline. The steam outlet of waste heat recovery unit 8 is connected to the steam inlet of fluidized bed gasifier 2 via a pipeline. The feed gas outlet of waste heat recovery unit 8 is connected to the inlet of water scrubbing tower 9 via a pipeline. The outlet of water scrubbing tower 9 is connected to the syngas inlet of decarbonization unit via a pipeline. The partial oxidation unit performs a partial oxidation reaction on the feed gas to generate low-methane syngas. The low-methane syngas outlet of the partial oxidation unit is connected to the low-methane syngas inlet of decarbonization unit via a pipeline. The outlet of decarbonization unit is connected to gas storage tank 11 via a pipeline.The carbon dioxide separated by the decarbonization unit flows back to the biomass gasification unit. The hydrogen inlet of the gas mixing tank 11 is connected to the hydrogen outlet of the water electrolysis unit via a pipeline. The hydrogen is mixed with the purified syngas produced by the decarbonization unit to form green methanol syngas. The hydrogen outlet of the water electrolysis unit is also connected to the hydrogen inlets of the biomass gasification unit and the partial oxidation unit via pipelines. The oxygen outlet of the water electrolysis unit is connected to the oxygen inlets of the biomass gasification unit and the partial oxidation unit via pipelines. The steam from the waste heat recovery and dust removal water washing purification unit... The steam outlets of both the gas outlet and the partial oxidation unit are connected to the steam inlet of the biomass gasification unit via pipelines. The water electrolysis unit includes an electrolysis cell 1, which is equipped with a hydrogen outlet and an oxygen outlet. The hydrogen outlet of the electrolysis cell 1 is connected via pipelines to the hydrogen inlets of the biomass gasification unit, the partial oxidation unit, and the gas mixing tank. The oxygen outlet of the electrolysis cell 1 is connected via pipelines to the oxygen inlets of the biomass gasification unit and the partial oxidation unit. The water electrolysis unit is powered by renewable energy to ensure the green and low-carbon characteristics of this system.

[0025] The decarbonization unit includes a decarbonization device 10. The syngas inlet of the decarbonization device 10 is connected to the outlet of the No. 2 water washing tower 9 through a pipeline. The carbon dioxide outlet of the decarbonization device 10 is connected to the carbon dioxide inlet of the fluidized bed gasifier 2 through a pipeline. The outlet of the decarbonization device 10 is connected to the gas storage tank 11 through a pipeline. The decarbonization unit is any one of a physical adsorption decarbonization device, a chemical absorption decarbonization device, or a membrane separation decarbonization device.

[0026] Example 1: Hydrogen ratio optimization for coupling of biomass gasification and decarbonization units. In this example, the hydrogen produced by the water electrolysis unit is divided into three parts:

[0027] First-stage hydrogen (30%): Directly introduced into the top of the biomass gasification unit to promote the reverse water-gas conversion reaction, converting some carbon dioxide into carbon monoxide, while effectively reducing the temperature at the top of the gasifier and optimizing gasification conditions.

[0028] Second-stage hydrogen (50%): fed into the partial oxidation unit, it is injected into the bottom of the high-temperature thermal reforming reactor to participate in the reverse water-gas shift reaction, further converting carbon dioxide into carbon monoxide, while simultaneously quenching the high-temperature gas to maintain a stable reaction temperature.

[0029] The third hydrogen (20%) is mixed with the feed gas purified by the decarbonization unit, and the final ratio of hydrogen to carbon monoxide is adjusted to 2.05:1 to ensure the optimal process requirements for green methanol synthesis gas.

[0030] Example 2: Hydrogen ratio adjustment to adapt to the processing of feed gas with high carbon dioxide concentration. When the carbon dioxide concentration of the feed gas is high, the hydrogen distribution ratio is adjusted as follows:

[0031] First-line hydrogen (40%): Increase the injection amount to the top of the biomass gasification unit, enhance the reverse water-gas shift reaction, increase the amount of carbon monoxide generated, and optimize the temperature distribution of the gasifier.

[0032] Second-stage hydrogen (40%): fed into the partial oxidation unit to regulate the temperature of the thermal reforming reaction, while converting excess carbon dioxide into carbon monoxide to reduce methane content.

[0033] The third hydrogen (20%): maintains the mixing ratio with the purified gas from the decarbonization unit, and the final hydrogen to carbon monoxide ratio in the syngas is controlled at 2.1:1 to meet the conversion requirements of gases with high carbon dioxide content.

[0034] Example 3: Hydrogen ratio optimization to adapt to low carbon dioxide concentration feed gas. Under the condition of low carbon dioxide concentration in the feed gas, the hydrogen distribution ratio is as follows:

[0035] First-line hydrogen (20%): Appropriately reduce the amount of hydrogen injected into the biomass gasification unit to avoid excessive carbon monoxide generation due to excessive reverse water-gas conversion reaction, thereby avoiding unnecessary energy consumption increase.

[0036] Second-stage hydrogen (50%): A large proportion is allocated to the partial oxidation unit to promote the generation of low-methane syngas, while optimizing the conversion efficiency of carbon dioxide in the feed gas.

[0037] Third-stage hydrogen (30%): Increases the mixing ratio with the purified gas from the decarbonization unit to ensure that the ratio of hydrogen to carbon monoxide reaches 1.8:1, adapting to methanol synthesis conditions under low carbon dioxide concentration.

[0038] The foregoing has shown and described the main features and advantages of the present invention. It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

[0039] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A system for producing green methanol synthesis gas by coupling biomass fluidized bed gasification with green hydrogen, characterized in that: The system includes a biomass gasification unit that uses pressurized fluidized bed gasification technology to suspend biomass feedstock and allow it to fully contact a gasifying agent for gasification to produce syngas. The feedstock gas outlet of the biomass gasification unit is connected via a pipeline to the feedstock gas inlet of a waste heat recovery and dust removal / washing purification unit. This unit performs waste heat recovery and purification on the feedstock gas. The feedstock gas outlet of this unit is also connected via a pipeline to the feedstock gas inlet of a partial oxidation unit. This unit performs partial oxidation on the feedstock gas to generate low-methane syngas. The low-methane syngas outlet of this unit is connected via a pipeline to the low-methane syngas inlet of a decarbonization unit. The gas outlet is connected to the gas mixing tank (11) via a pipe. The carbon dioxide separated by the decarbonization unit flows back to the biomass gasification unit. The hydrogen inlet of the gas mixing tank (11) is connected to the hydrogen outlet of the water electrolysis unit via a pipe. The hydrogen is mixed with the purified synthesis gas generated by the decarbonization unit to form green methanol synthesis gas. The hydrogen outlet of the water electrolysis unit is also connected to the hydrogen inlets of the biomass gasification unit and the partial oxidation unit via pipes. The oxygen outlet of the water electrolysis unit is connected to the oxygen inlets of the biomass gasification unit and the partial oxidation unit via pipes. The steam outlet of the waste heat recovery and dust removal water washing purification unit and the steam outlet of the partial oxidation unit are both connected to the steam inlet of the biomass gasification unit via pipes.

2. The system for producing green methanol synthesis gas by coupling biomass fluidized bed gasification with green hydrogen according to claim 1, characterized in that: The water electrolysis unit includes an electrolysis cell (1), which is provided with a hydrogen outlet and an oxygen outlet. The hydrogen outlet of the electrolysis cell (1) is connected to the hydrogen inlet of the biomass gasification unit, the partial oxidation unit and the gas mixing tank through pipes. The oxygen outlet of the electrolysis cell (1) is connected to the oxygen inlet of the biomass gasification unit and the partial oxidation unit through pipes.

3. The system for producing green methanol synthesis gas by coupling biomass fluidized bed gasification with green hydrogen according to claim 2, characterized in that: The biomass gasification unit includes a fluidized bed gasifier (2). The hydrogen inlet at the upper end of the fluidized bed gasifier (2) is connected to the hydrogen inlet of the electrolytic cell (1) through a pipe. The raw material gas outlet of the fluidized bed gasifier (2) is connected to the raw material gas inlet of the waste heat recovery and dust removal water washing purification unit through a pipe. The oxygen inlet of the fluidized bed gasifier (2) is connected to the oxygen outlet of the electrolytic cell (1) through a pipe. The steam inlet of the fluidized bed gasifier (2) is connected to the steam outlet of the waste heat recovery and dust removal water washing purification unit and the partial oxidation unit through pipes respectively. The carbon dioxide inlet of the fluidized bed gasifier (2) is connected to the carbon dioxide outlet of the decarbonization unit through a pipe.

4. The system for producing green methanol synthesis gas by coupling biomass fluidized bed gasification with green hydrogen according to claim 3, characterized in that: The waste heat recovery and dust removal water washing purification unit includes a No. 1 waste heat recovery unit (3). The air inlet of the No. 1 waste heat recovery unit (3) is connected to the raw material gas outlet of the fluidized bed gasifier (2) through a pipeline. The steam outlet of the No. 1 waste heat recovery unit (3) is connected to the steam inlet of the fluidized bed gasifier (2) through a pipeline. The air outlet of the No. 1 waste heat recovery unit (3) is connected to the air inlet of the cyclone separator (4) through a pipeline. The air outlet of the cyclone separator (4) is connected to the air inlet of the No. 1 water washing tower (5) through a pipeline. The raw material gas outlet of the No. 1 water washing tower (5) is connected to the raw material gas inlet of the partial oxidation unit through a pipeline.

5. The system for producing green methanol synthesis gas by coupling biomass fluidized bed gasification with green hydrogen according to claim 4, characterized in that: The partial oxidation unit includes a gas integration box (6). The oxygen inlet of the gas integration box (6) is connected to the oxygen outlet of the electrolytic cell (1) through a pipe. The raw material gas inlet of the gas integration box (6) is connected to the raw material gas outlet of the No. 1 water washing tower (5) through a pipe. The raw material gas outlet of the gas integration box (6) is connected to the inlet of the POX furnace (7) through a pipe. The hydrogen inlet of the POX furnace (7) is connected to the hydrogen outlet of the electrolytic cell (1) through a pipe. The outlet of the POX furnace (7) is connected to the inlet of the No. 2 waste heat recovery unit (8) through a pipe. The steam outlet of the No. 2 waste heat recovery unit (8) is connected to the steam inlet of the fluidized bed gasifier (2) through a pipe. The raw material gas outlet of the No. 2 waste heat recovery unit (8) is connected to the inlet of the No. 2 water washing tower (9) through a pipe. The outlet of the No. 2 water washing tower (9) is connected to the synthesis gas inlet of the decarbonization unit through a pipe.

6. The system for producing green methanol synthesis gas by coupling biomass fluidized bed gasification with green hydrogen according to claim 5, characterized in that: The decarbonization unit includes a decarbonization device (10). The syngas inlet of the decarbonization device (10) is connected to the outlet of the No. 2 water washing tower (9) through a pipeline. The carbon dioxide outlet of the decarbonization device (10) is connected to the carbon dioxide inlet of the fluidized bed gasifier (2) through a pipeline. The outlet of the decarbonization device (10) is connected to the gas storage tank (11) through a pipeline.

7. The system for producing green methanol synthesis gas by coupling biomass fluidized bed gasification with green hydrogen according to claim 6, characterized in that: The decarbonization unit can be any one of a physical adsorption decarbonization device, a chemical absorption decarbonization device, or a membrane separation decarbonization device.

8. A system for producing green methanol synthesis gas by coupling biomass fluidized bed gasification with green hydrogen according to claim 2, characterized in that: The water electrolysis unit is powered by renewable energy to ensure the green and low-carbon characteristics of the system.

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