System and method for producing syngas by coupling biomass dual fluidized-bed chemical looping gasification with oxygen-enriched combustion
Patent Information
- Application Number
- PCT/CN2026/083138
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2025-03-12
- Filing Date
- 2026-03-12
- Publication Date
- 2026-09-17
Smart Images
Figure CN2026083138_17092026_PF_FP_ABST
Abstract
Description
A system and method for producing syngas by coupling biomass dual-fluidized bed chemical looping gasification and oxygen-enriched combustion. Technical Field
[0001] This invention relates to the fields of energy, environmental protection and chemical technology, specifically to a system and method for producing syngas by coupling biomass dual fluidized bed chemical looping gasification and oxygen-enriched combustion. Background Technology
[0002] Developing green liquid fuel (such as methanol and aviation kerosene) production technologies is one of the important ways to ensure my country's energy security and optimize its energy structure. It is of great significance for promoting my country's industrial upgrading and achieving "dual-carbon" goals and sustainable development in transportation, chemical and other fields. Taking methanol as an example, global methanol production reached 110 million tons in 2022, but green methanol production was only about 500,000 tons, less than 1%, indicating a vast market demand.
[0003] Biomass is the only renewable resource that can be directly converted into carbon-containing liquid fuels, playing an irreplaceable role in the production of green liquid fuels. Gasification synthesis is one of the most efficient routes for producing green liquid fuels using biomass as a raw material. This route first converts biomass into syngas (CO + H2) through gasification, and then uses the syngas to produce liquid fuels through catalytic synthesis. For example, patent CN119020073A proposes a biomass dual fluidized bed coupled with water electrolysis to produce hydrogen. Using steam as the gasifying agent, a dual fluidized bed gasifier produces high-quality syngas, which is then combined with hydrogen obtained from the water electrolysis system to produce liquid fuels, effectively reducing energy consumption and costs in the production process.
[0004] Unlike traditional gasification technologies, biomass dual-fluidized bed chemical looping gasification technology uses an oxygen carrier instead of a traditional gasifying agent. The oxygen carrier circulates between a combustion reactor and a gasification reactor, transferring oxygen from the air to the biomass. This achieves high-quality syngas production without air separation and at low cost, and related technologies have developed rapidly in recent years. For example, patent CN114574250A proposes a method and apparatus for producing clean syngas from biomass through chemical looping gasification. Utilizing a dual-circulation oxygen carrier and a tar-carbon dioxide reforming catalyst, it achieves in-situ efficient conversion of tar and carbon dioxide in biomass gasification and its gaseous products, improving the yield and quality of syngas and significantly enhancing atomic and energy utilization.
[0005] Besides gasification technology, biomass can also be used to produce carbon dioxide through oxygen-enriched combustion, which can then be combined with green hydrogen to produce green liquid fuels. For example, patent CN113944544A proposes an energy system based on renewable energy and hydrogen-based methanol synthesis, which uses carbon dioxide produced by oxygen-enriched combustion of biomass and hydrogen produced by water electrolysis to synthesize methanol. This system can effectively absorb renewable energy electricity and achieve zero or negative carbon emissions.
[0006] In existing biomass dual-fluidized bed chemical looping gasification processes, some residual carbon remains in the gasification reactor. This carbon is carried by the oxygen carrier into the combustion reactor and burned into carbon dioxide. Since the main component of the flue gas after combustion is nitrogen, and carbon dioxide capture costs are high, this flue gas is generally directly discharged after waste heat recovery and purification, resulting in low carbon utilization in the biomass during chemical looping gasification. While direct oxygen-enriched combustion technology for biomass has a higher carbon utilization rate, its main product is carbon dioxide, which has a high degree of oxidation. Subsequent hydrogenation processes, such as those for methanol and jet fuel production, require additional hydrogen for deoxygenation, placing high demands on reaction conditions and resulting in relatively lower atom utilization and energy efficiency.
[0007] Therefore, existing technologies still need to be improved and developed. Summary of the Invention
[0008] In view of the shortcomings of the prior art, the purpose of this invention is to provide a system and method for producing syngas by coupling biomass dual fluidized bed chemical looping gasification and oxygen-enriched combustion. This aims to solve the problem of low carbon conversion rate in current biomass chemical looping gasification, and to achieve the simultaneous production of high-quality syngas and high-concentration carbon dioxide from biomass for subsequent synthesis of green liquid fuels such as methanol and aviation kerosene, thereby improving the material and energy utilization efficiency and process flexibility of the production process.
[0009] The technical solution of the present invention is as follows:
[0010] As shown in Figure 1, the present invention provides a system for producing syngas by coupling biomass dual fluidized bed chemical looping gasification and oxygen-enriched combustion. The system includes a silo (1), a feeder (2), a fluidized bed gasifier (3), a lower return feeder (4), a fluidized bed oxygen-enriched combustion furnace (5), a gasifier cyclone separator (6), a syngas heat exchanger (7), a syngas purifier (8), a combustion furnace cyclone separator (9), an upper return feeder (10), a flue gas heat exchanger (11), and a flue gas purifier (12).
[0011] The silo (1) is connected to the feeder (2), which is connected to the fluidized bed gasifier (3) to feed biomass (101) into the fluidized bed gasifier (3). The fluidized bed gasifier (3) is connected to the return feeder (4) and the gasifier cyclone separator (6) to feed biomass residue and reducing oxygen carrier (301) into the return feeder (4) and syngas (302) into the gasifier cyclone separator (6). The gasifier cyclone separator (6) is connected to the syngas heat exchanger (7) to feed high-temperature syngas (601) into the syngas heat exchanger (7). The syngas heat exchanger (7) is connected to the syngas purifier (8) to feed low-temperature syngas (701) into the syngas purifier (8). The syngas purifier (8) is connected to the fluidized bed gasifier (3) and the subsequent chemical synthesis unit, respectively. A portion of the purified syngas is transported to the fluidized bed gasifier (3) as circulating syngas (801), and the remainder is input into the subsequent chemical synthesis unit as product syngas (802). The feeder (4) is connected to the fluidized bed oxygen-enriched combustion furnace (5), and transports biomass residue and reducing oxygen carrier to the fluidized bed oxygen-enriched combustion furnace (5). The fluidized bed oxygen-enriched combustion furnace (5) is connected to the combustion furnace cyclone separator (9), and inputs flue gas and oxygen carrier (501) into the combustion furnace cyclone separator (9), while ash (502) is discharged from the bottom of the fluidized bed oxygen-enriched combustion furnace (5). The combustion furnace cyclone separator (9) is connected to the upper return feeder (10) and the flue gas heat exchanger (11) respectively, inputting the oxygen carrier (901) into the upper return feeder (10) and the high-temperature flue gas (902) into the flue gas heat exchanger (11). The upper return feeder (10) is connected to the fluidized bed gasifier (3) and is used to transport the oxygen carrier back to the fluidized bed gasifier (3). The flue gas heat exchanger (11) is connected to the flue gas purifier (12) and is used to input the low-temperature flue gas (1101) into the flue gas purifier (12). The flue gas purifier (12) is connected to the fluidized bed oxygen-enriched combustion furnace (5) and the subsequent chemical synthesis unit respectively, and a portion of the purified flue gas is transported to the fluidized bed combustion furnace (5) as circulating carbon dioxide (1201), and the remainder is input into the subsequent chemical synthesis unit as product carbon dioxide (1202).
[0012] A method for producing syngas by coupling biomass dual-fluidized bed chemical looping gasification and oxygen-enriched combustion, wherein the syngas is produced using the system described in this invention, and the method for producing syngas includes the following steps:
[0013] The biomass (101) in the silo (1) is transported to the fluidized bed gasifier (3) by the feeder (2). In the fluidized bed gasifier (3), the biomass (101) comes into contact with the high-temperature oxidizing oxygen carrier (901) and undergoes a chemical chain gasification reaction to obtain syngas (302) mainly composed of CO and H2. The syngas (302) leaves the fluidized bed gasifier (3) from the top and enters the gasifier cyclone separator (6). After being separated by the cyclone, the fly ash (602) enters the syngas heat exchanger (7). The remaining solid biomass carbon residue and reducing oxygen carrier (301) after the reaction leave the fluidized bed gasifier (3) from the bottom under the action of gravity and enter the lower return feeder (4). In the lower return feeder (4), the biomass carbon residue and reducing oxygen carrier (301) enter the bottom of the fluidized bed oxygen-enriched combustion furnace (5) under the action of the lower return air (401).
[0014] In the fluidized bed oxygen-enriched combustion furnace (5), biomass residue and reducing oxygen carrier (301) come into contact with oxygen (503) in the fluidizing gas. The biomass residue undergoes an oxygen-enriched combustion reaction, generating flue gas mainly composed of CO2 and H2O. The reducing oxygen carrier undergoes an oxidation reaction, transforming back into an oxidizing oxygen carrier. The reacted flue gas and oxygen carrier (501) exit the fluidized bed oxygen-enriched combustion furnace (5) from the top and enter the combustion furnace cyclone separator (9). The ash (502) produced after the biomass residue combustion is discharged from the bottom of the fluidized bed oxygen-enriched combustion furnace (5). In the combustion furnace cyclone separator (9), the high-temperature flue gas is separated from the oxidizing oxygen carrier by cyclone action. The oxidizing oxygen carrier (901) enters the upper return feeder (10) and, under the action of the upper return air (1001), returns to the fluidized bed gasifier (3) to repeat the chemical looping gasification reaction with the biomass (101). The high-temperature flue gas (902) then enters the flue gas heat exchanger (11).
[0015] In the syngas heat exchanger (7), waste heat is recovered by exchanging heat between high-temperature syngas (601) and water or circulating syngas. The cooled low-temperature syngas (701) enters the syngas purifier (8) for purification, further removing impurities such as dust and tar contained in the syngas. Part of the purified syngas is used as circulating syngas (801), which is preheated and then fed into the fluidized bed gasifier (3). The remainder is used as product syngas (802) and fed into the subsequent chemical synthesis system.
[0016] In the flue gas heat exchanger (11), waste heat is recovered by exchanging heat between high-temperature flue gas (902) and water or circulating carbon dioxide. The cooled low-temperature flue gas (1101) enters the flue gas purifier (12) for purification treatment, removing dust and other pollutant components from the flue gas to obtain a gas mainly composed of carbon dioxide. Among them, part of the carbon dioxide is used as circulating carbon dioxide (1201), which is preheated and mixed with oxygen (503) in a certain proportion and fed into the fluidized bed oxygen-enriched combustion furnace (5). The remainder is used as product carbon dioxide (1202) and fed into the subsequent chemical synthesis system.
[0017] Preferably, the temperature of the fluidized bed gasifier (3) is 700-950℃, and the temperature of the fluidized bed oxygen-enriched combustion furnace (5) is 750-1000℃.
[0018] Preferably, the fluidizing gas of the fluidized bed gasifier (3) is recycled syngas or steam or a mixture of recycled syngas and steam; the fluidizing gas of the fluidized bed oxygen-enriched combustion furnace (5) is a mixture of recycled carbon dioxide (1201) and oxygen (503), wherein the oxygen (503) is derived from by-product oxygen from water electrolysis or oxygen obtained from air separation, and the volume concentration of oxygen (503) in the mixture is 21%-50%.
[0019] Preferably, the lower return device (4) is a U-shaped valve, a V-shaped valve, an L-shaped valve, or a mechanical return valve, the upper return device (10) is a U-shaped valve, a V-shaped valve, an L-shaped valve, or a mechanical return valve, the lower return air (401) is steam or circulating carbon dioxide, and the upper return air (1001) is steam or circulating synthesis gas.
[0020] Preferably, the syngas heat exchanger (7) is used to produce steam or preheat the circulating syngas (801) after heat exchange, and the flue gas heat exchanger (11) is used to produce steam or preheat the circulating carbon dioxide (1201) after heat exchange.
[0021] Preferably, the biomass described in this invention includes, but is not limited to, one or more of the following: crop straw, forestry waste, municipal solid waste, and sludge. For primary biomass, it should be pre-treated, such as by crushing, before being input into the system described in this invention.
[0022] The present invention has the following beneficial effects: (1) By coupling biomass dual fluidized bed chemical chain gasification with oxygen-enriched combustion technology, the co-production of high-quality syngas and high-concentration carbon dioxide is realized, which effectively improves the flexibility of the process organization for producing green liquid fuels from biomass; (2) By replacing the air-fired furnace in the traditional biomass dual fluidized bed chemical chain gasification technology with an oxygen-enriched furnace, the residual carbon remaining in the traditional biomass chemical chain gasification process is further converted into high-concentration carbon dioxide through oxygen-enriched combustion. The flue gas (the effective component is carbon dioxide) that could not be recovered at low cost by the original air-fired furnace can be efficiently recovered and used as a raw material for chemical synthesis, thereby improving the carbon conversion rate in biomass and solving the problem of low carbon conversion rate of raw materials in the current biomass chemical chain gasification process; (3) Through chemical chain gasification technology, most of the carbon in biomass is converted into carbon monoxide, and only a small part is converted into carbon dioxide through oxygen-enriched combustion. While ensuring the high carbon conversion rate of biomass, the requirements for subsequent green liquid fuel synthesis process parameters are effectively reduced, and the energy efficiency of the system is improved. Attached Figure Description
[0023] Figure 1 is a schematic diagram of a biomass dual fluidized bed chemical looping gasification and oxygen-enriched combustion coupled syngas production system according to the present invention.
[0024] Figure 2 is a schematic diagram of a biomass dual fluidized bed chemical looping gasification and oxygen-enriched combustion coupled syngas production system according to a specific embodiment.
[0025] In the diagram: 1-Hopper; 2-Feeder; 3-Fluidized bed gasifier; 4-Lower return feeder; 5-Fluidized bed oxygen-enriched combustion furnace; 6-Gasifier cyclone separator; 7-Synthetic gas heat exchanger; 8-Synthetic gas purifier; 9-Combustion furnace cyclone separator; 10-Upper return feeder; 11-Flue gas heat exchanger; 12-Flue gas purifier; 13-Water electrolysis unit; 14-Methanol synthesis unit; 101-Biomass; 301-Biomass residual carbon and reducing oxygen carrier; 302-Synthetic gas; 401-Lower return air; 501-Flue gas and oxygen carrier; 502-Ash; 503-Oxygen; 60 1-High-temperature syngas; 602-Fly ash; 701-Low-temperature syngas; 702-Syngas waste heat; 801-Circulating syngas or steam; 802-Product syngas; 803-Syngas impurities such as dust and tar; 901-Oxidizing oxygen carrier; 902-High-temperature flue gas; 1001-Top return air; 1101-Low-temperature flue gas; 1102-Flue gas waste heat; 1201-Circulating carbon dioxide; 1202-Product carbon dioxide; 1203-Flue gas impurities such as dust; 1301-Wind power; 1302-Water; 1303-Hydrogen; 1401-Green methanol. Detailed Implementation
[0026] This invention provides a system and method for producing syngas by coupling biomass dual-fluidized bed chemical looping gasification with oxygen-enriched combustion. To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention is further described in detail below. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
[0027] Referring to Figure 2, this embodiment of the invention provides a system and method for producing syngas by coupling biomass dual fluidized bed chemical looping gasification and oxygen-enriched combustion. The biomass is compressed pellets made from wood processing waste (the characteristics of which are shown in Table 1). Oxygen is generated by wind power electrolysis of water. The syngas is used to produce green methanol. The system has an annual biomass processing capacity of 50,000 tons (dry basis), as detailed below:
[0028] (1) The system for processing the above biomass includes a silo 1, a feeder 2, a fluidized bed gasifier 3, a bottom return feeder 4, a fluidized bed oxygen-enriched combustion furnace 5, a gasifier cyclone separator 6, a syngas heat exchanger 7, a syngas purifier 8, a combustion furnace cyclone separator 9, an upper return feeder 10, a flue gas heat exchanger 11, a flue gas purifier 12, a water electrolysis unit 13, and a methanol synthesis unit 14.
[0029] (2) The biomass 101 in the silo 1 is transported to the fluidized bed gasifier 3 using the feeder 2. In the fluidized bed gasifier 3, the biomass 101 comes into contact with the high-temperature oxidizing oxygen carrier 901 returned from the fluidized bed oxygen-enriched combustion furnace 5 and undergoes a chemical looping gasification reaction at a temperature of 900°C, yielding syngas 302, which is mainly composed of CO and H2. The generated syngas 302 leaves the fluidized bed gasifier 3 from the top and enters the gasifier cyclone separator 6. After being separated by the cyclone, the fly ash 602 is separated and then enters the syngas heat exchanger 7. The remaining solid biomass residue and reducing oxygen carrier 301 leave the fluidized bed gasifier 3 from the bottom under gravity and enter the U-shaped bottom return feeder 4. In the bottom return feeder 4, the biomass residue and reducing oxygen carrier 301 are fed into the bottom of the fluidized bed oxygen-enriched combustion furnace 5 using circulating carbon dioxide as the fluidizing gas.
[0030] (3) In the fluidized bed oxygen-enriched combustion furnace 5, biomass residue and reducing oxygen carrier 301 come into contact with oxygen 503 generated by water electrolysis (oxygen accounts for 30% of the volume concentration of fluidized bed combustion gas), resulting in oxygen-enriched combustion and oxidation reactions at a reaction temperature of 950℃. The biomass residue combustion produces flue gas mainly composed of CO2 and H2O. The reducing oxygen carrier undergoes an oxidation reaction, transforming back into an oxidizing oxygen carrier. The reacted flue gas and oxygen carrier 501 exit the fluidized bed oxygen-enriched combustion furnace 5 from the top and enter the combustion furnace cyclone separator 9. The ash 502 produced during the biomass residue combustion process is discharged from the bottom of the fluidized bed oxygen-enriched combustion furnace 5. In the combustion furnace cyclone separator 9, the high-temperature flue gas 902 is separated from the oxidizing oxygen carrier 901 by cyclone action. Among them, the oxygen carrier 901 enters the U-shaped upper return feeder 10, and returns to the fluidized bed gasifier 3 under the action of the upper return air 1001 (the upper return air adopts the circulating synthesis gas), repeating the chemical chain gasification reaction with the biomass 101, while the high-temperature flue gas 902 enters the flue gas heat exchanger 11.
[0031] (4) In the syngas heat exchanger 7, the circulating syngas 801 is preheated by high-temperature syngas 601 to increase the temperature of the circulating syngas 801 entering the fluidized bed gasifier 3. Then, the high-temperature syngas 601 is used to produce low-pressure steam for external supply, further recovering waste heat. The cooled low-temperature syngas 701 enters the syngas purifier 8 for purification treatment to further remove syngas impurities 803 such as dust and tar contained in the syngas. Part of the purified syngas is used as circulating syngas 801, which is preheated and then fed into the fluidized bed gasifier 3. The remainder is used as product syngas 802 and fed into the methanol synthesis unit 14.
[0032] (5) In the flue gas heat exchanger 11, the circulating carbon dioxide 1201 is first preheated by the high-temperature flue gas 902, and then the high-temperature flue gas 902 is used to produce low-pressure steam for external supply, further recovering waste heat. The cooled low-temperature flue gas 1101 enters the flue gas purifier 12 for purification treatment, removing dust and other pollutants 1203 from the flue gas, and obtaining a gas mainly composed of carbon dioxide. Among them, a portion is used as circulating carbon dioxide 1201, which is preheated and mixed with oxygen 503 generated by the water electrolysis unit 13 in a certain proportion (oxygen: carbon dioxide = 3:7, volume ratio), and fed into the fluidized bed oxygen-enriched combustion furnace 5, and the remainder is used as product carbon dioxide 1202 and fed into the methanol synthesis unit 14.
[0033] (6) In the water electrolysis unit 13, renewable wind power 1301 is used for water electrolysis. Part of the generated oxygen is fed into the fluidized bed oxygen-enriched combustion furnace 5 as oxygen 503 required for oxygen-enriched combustion, and the remainder is supplied as product. The generated hydrogen 1303 is fed into the methanol synthesis unit 14 as feed gas, and is mixed and blended with product synthesis gas 802 and product carbon dioxide 1202 to synthesize green methanol 1401 under the action of a catalyst.
[0034] Table 1. Biomass feedstock industry, elemental and calorific value analysis
[0035] The main performance parameters of the system during stable operation in this embodiment are shown in Table 2, and the main components of the product syngas are shown in Table 3.
[0036] Table 2. System Performance Parameters
[0037] Table 3. Analysis of the main components of the product syngas
[0038] In summary, this invention provides a system and method for producing syngas by coupling biomass dual fluidized bed chemical looping gasification and oxygen-enriched combustion. Specifically, biomass is fed into a fluidized bed gasifier via a feeder, where it contacts the oxygen carrier returned from the fluidized bed combustion furnace and undergoes a chemical looping gasification reaction to generate syngas. After heat exchange and purification, a portion of the syngas is returned to the fluidized bed gasifier as recirculated gas, while the remainder is output as product. The oxygen carrier and residual biomass carbon from the fluidized bed gasifier reaction are returned to the fluidized bed oxygen-enriched combustion furnace for oxidation and combustion reactions with oxygen. The oxidized oxygen carrier is then returned to the fluidized bed gasifier to undergo gasification with the biomass. The flue gas, after heat exchange and purification, is also partially returned to the fluidized bed oxygen-enriched combustion furnace as recirculated gas, with the remainder output as product. This invention couples biomass dual-fluidized bed chemical looping gasification with oxygen-enriched combustion technology to achieve the co-production of high-quality syngas and high-concentration carbon dioxide, effectively improving the flexibility of the process organization for producing green liquid fuels from biomass. By applying oxygen-enriched combustion technology in a fluidized bed combustion furnace, the residual carbon from the biomass chemical looping gasification process is further converted into high-concentration carbon dioxide and recycled, solving the problem of low carbon conversion rate in the current biomass chemical looping gasification process and effectively improving material utilization efficiency. Through chemical looping gasification technology, most of the carbon in biomass is converted into carbon monoxide, with only a small portion converted into carbon dioxide through oxygen-enriched combustion. While ensuring a high carbon conversion rate of biomass, this effectively reduces the requirements for subsequent green liquid fuel synthesis process parameters and improves the system's energy efficiency.
[0039] It should be understood that the application of the present invention is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.
Claims
1. A system for producing syngas by coupling biomass dual-fluidized bed chemical looping gasification and oxygen-enriched combustion, characterized in that, The system includes a silo (1), a feeder (2), a fluidized bed gasifier (3), a lower return feeder (4), a fluidized bed oxygen-enriched combustion furnace (5), a gasifier cyclone separator (6), a syngas heat exchanger (7), a syngas purifier (8), a combustion furnace cyclone separator (9), an upper return feeder (10), a flue gas heat exchanger (11), and a flue gas purifier (12). The silo (1) is sequentially connected to the feeder (2) and the fluidized bed gasifier (3). The feeder (2) feeds the biomass (101) in the silo (1) into the fluidized bed gasifier (3). The fluidized bed gasifier (3) is connected to the return feeder (4) and the gasifier cyclone separator (6). Biomass residual carbon and reducing oxygen carrier (301) are fed into the return feeder (4), and syngas (302) is fed into the gasifier cyclone separator (6). The gasifier cyclone separator (6) is connected to the syngas heat exchanger (7). Next, high-temperature syngas (601) is input into the syngas heat exchanger (7); the syngas heat exchanger (7) is connected to the syngas purifier (8), and low-temperature syngas (701) is input into the syngas purifier (8); the syngas purifier (8) is connected to the fluidized bed gasifier (3) and the subsequent chemical synthesis unit respectively, and the circulating syngas (801) is transported to the fluidized bed gasifier (3), and the product syngas (802) is input into the subsequent chemical synthesis unit; the feeder (4) is connected to the fluidized bed oxygen-enriched combustion furnace (5), and the biological feeder is used to feed the product syngas (802) into the subsequent chemical synthesis unit. The residual carbon and reducing oxygen carrier are transported to the fluidized bed oxygen-enriched combustion furnace (5); the fluidized bed oxygen-enriched combustion furnace (5) is connected to the combustion furnace cyclone separator (9), and the flue gas and oxygen carrier (501) are input into the combustion furnace cyclone separator (9), while the ash (502) is discharged from the bottom of the fluidized bed oxygen-enriched combustion furnace (5); the combustion furnace cyclone separator (9) is connected to the upper return feeder (10) and the flue gas heat exchanger (11) respectively, and the oxidizing oxygen carrier (901) is input into the upper return feeder (10), while the high-temperature flue gas (902) is input into the flue gas heat exchanger (11). 11); The upper return feeder (10) is connected to the fluidized bed gasifier (3) to input the oxygen carrier into the fluidized bed gasifier (3); The flue gas heat exchanger (11) is connected to the flue gas purifier (12) to input the low temperature flue gas (1101) into the flue gas purifier (12); The flue gas purifier (12) is connected to the fluidized bed oxygen-enriched combustion furnace (5) and the subsequent chemical synthesis unit respectively, to transport the recycled carbon dioxide (1201) to the fluidized bed oxygen-enriched combustion furnace (5) and to input the product carbon dioxide (1202) into the subsequent chemical synthesis unit.
2. A method for producing syngas by coupling biomass dual-fluidized bed chemical looping gasification and oxygen-enriched combustion, characterized in that, Syngas is produced using the biomass dual fluidized bed chemical looping gasification and oxygen-enriched combustion coupled system as described in claim 1, wherein the method for producing syngas includes the following steps: The biomass (101) in the silo (1) is transported to the fluidized bed gasifier (3) by the feeder (2). In the fluidized bed gasifier (3), the biomass (101) comes into contact with the high-temperature oxidizing oxygen carrier and undergoes a chemical chain gasification reaction to obtain syngas (302) mainly composed of CO and H2. The syngas (302) leaves the fluidized bed gasifier (3) from the top and enters the gasifier cyclone separator (6). After the fly ash (602) is separated by the cyclone, the high-temperature syngas (601) enters the syngas heat exchanger (7). The remaining solid biomass carbon residue and reducing oxygen carrier (301) after the reaction leave the fluidized bed gasifier (3) from the bottom under the action of gravity and enter the lower return feeder (4). In the lower return feeder (4), the biomass carbon residue and reducing oxygen carrier (301) enter the bottom of the fluidized bed oxygen-enriched combustion furnace (5) under the action of the lower return air (401). In the fluidized bed oxygen-enriched combustion furnace (5), biomass residue and reducing oxygen carrier (301) come into contact with oxygen (503) in the fluidizing gas; wherein, the biomass residue undergoes an oxygen-enriched combustion reaction to generate flue gas mainly composed of CO2 and H2O, while the reducing oxygen carrier undergoes an oxidation reaction and is transformed back into an oxidizing oxygen carrier. The flue gas and oxygen carrier (501) after the reaction leave the fluidized bed oxygen-enriched combustion furnace (5) from the top and enter the combustion furnace cyclone separator (9); the biomass residue combustion The ash (502) produced is discharged from the bottom of the fluidized bed oxygen-enriched combustion furnace (5); in the combustion furnace cyclone separator (9), the high temperature flue gas is separated from the oxygen carrier by the action of cyclone. The oxygen carrier (901) enters the upper return feeder (10) and returns to the fluidized bed gasifier (3) under the action of the upper return air (1001) to repeat the chemical chain gasification reaction with biomass (101), while the high temperature flue gas (902) enters the flue gas heat exchanger (11). In the syngas heat exchanger (7), waste heat is recovered by exchanging heat between high-temperature syngas (601) and water or circulating syngas. The cooled low-temperature syngas (701) enters the syngas purifier (8) for purification to remove impurities contained in the syngas. Part of the purified syngas is used as circulating syngas (801), which is preheated and then fed into the fluidized bed gasifier (3). The remainder is used as product syngas (802) and fed into the subsequent chemical synthesis unit. In the flue gas heat exchanger (11), waste heat is recovered by exchanging heat between high-temperature flue gas (902) and water or circulating carbon dioxide. The cooled low-temperature flue gas (1101) enters the flue gas purifier (12) for purification treatment to remove pollutants from the flue gas and obtain a gas mainly composed of carbon dioxide. Among them, part of the carbon dioxide is used as circulating carbon dioxide (1201), which is preheated and mixed with oxygen (503) and fed into the fluidized bed oxygen-enriched combustion furnace (5). The remainder is used as product carbon dioxide (1202) and fed into the subsequent chemical synthesis unit.
3. The method for producing syngas by coupling biomass dual-fluidized bed chemical looping gasification and oxygen-enriched combustion according to claim 2, characterized in that, The temperature of the fluidized bed gasifier (3) is 700-950℃, and the temperature of the fluidized bed oxygen-enriched combustion furnace (5) is 750-1000℃.
4. The method for producing syngas by coupling biomass dual-fluidized bed chemical looping gasification and oxygen-enriched combustion according to claim 2, characterized in that, The fluidizing gas in the fluidized bed gasifier (3) is either circulating syngas or steam or a mixture of circulating syngas and steam.
5. The method for producing syngas by coupling biomass dual-fluidized bed chemical looping gasification and oxygen-enriched combustion according to claim 2, characterized in that, The fluidizing gas in the fluidized bed oxygen-enriched combustion furnace (5) is a mixture of circulating carbon dioxide (1201) and oxygen (503). The oxygen (503) is derived from by-product oxygen produced by water electrolysis or oxygen obtained by air separation. The volume concentration of oxygen (503) in the mixture is 21%-50%.
6. The method for producing syngas by coupling biomass dual-fluidized bed chemical looping gasification and oxygen-enriched combustion according to claim 2, characterized in that, The lower return valve (4) is a U-shaped valve, a V-shaped valve, an L-shaped valve, or a mechanical return valve; the upper return valve (10) is a U-shaped valve, a V-shaped valve, an L-shaped valve, or a mechanical return valve; the lower return air (401) is steam or circulating carbon dioxide; and the upper return air (1001) is steam or circulating synthesis gas.
7. The method for producing syngas by coupling biomass dual-fluidized bed chemical looping gasification and oxygen-enriched combustion according to claim 2, characterized in that, The syngas heat exchanger (7) is used to produce steam or preheat the circulating syngas (801) after heat exchange, and the flue gas heat exchanger (11) is used to produce steam or preheat the circulating carbon dioxide (1201) after heat exchange.
8. The method for producing syngas by coupling biomass dual-fluidized bed chemical looping gasification and oxygen-enriched combustion according to claim 2, characterized in that, The biomass includes one or more of crop straw, forestry waste, municipal solid waste and sludge, and the biomass is fed into the silo (1) after pretreatment.