An integrated method for flue gas recirculation biomass roasting-gasification enhanced by magnesium-based additives

Abstract

This invention provides an integrated method for biomass roasting and gasification based on magnesium-based additives, belonging to the field of biomass energy technology. This method improves the fuel quality of roasted biomass products by optimizing the flue gas recirculation components and the synergistic effect of magnesium-based additives, achieving in-situ CO2 gasification. Furthermore, it enhances the gasification reaction activity through alkali metal catalysis, thereby optimizing the gasification process. This technology improves the stability of biomass fuel gasification, optimizes the quality of syngas, and reduces the formation of tar byproducts. While efficiently utilizing waste heat from flue gas to roast biomass and increase fuel energy density, it also utilizes the adsorption properties of magnesium oxide to capture CO2, improving the quality of syngas and thus increasing the thermochemical conversion efficiency of biomass. This invention, to a certain extent, solves the problems of high tar byproduct content, low gasification efficiency, and unstable gas product quality in traditional biomass gasification processes, providing a new technical path for industrial applications.

Description

Technical Field

[0001] This invention relates to the field of biomass energy technology, and in particular to an integrated method for flue gas recirculation biomass roasting-gasification based on magnesium-based additives. Background Technology

[0002] Global warming is becoming increasingly severe; since the Industrial Revolution, global temperatures have risen by more than 1°C, primarily due to the increased atmospheric CO2 concentration caused by the combustion of fossil fuels. To address this challenge, biomass, as a renewable energy source, has attracted significant attention. Its abundant reserves and carbon-neutral properties make it an important alternative to fossil fuels.

[0003] Gasification technology is an important pathway for the utilization of biomass resources, offering broad adaptability to different feedstocks and flexible gas production capabilities. However, biomass naturally suffers from high oxygen content and low energy density, making direct gasification economically unfeasible. Therefore, appropriate pretreatment before gasification is crucial for improving biomass fuel performance.

[0004] In recent years, torrefaction has been considered an effective method to improve gasification efficiency due to its ability to improve biomass fuel characteristics, reduce the O / C ratio, and increase energy density and higher heating value (HHV). Studies have shown that torrefaction of biomass exhibits higher H2 and CO yields during gasification. However, traditional torrefaction technologies typically use inert atmospheres such as N2 or CO2, resulting in high costs and underutilization of flue gas waste heat resources. Therefore, flue gas torrefaction (FGT) has become a research hotspot in recent years. This method utilizes flue gas as a heat source and atmosphere to further enhance the gasification performance of torrefaction products from biomass.

[0005] Building upon this foundation, research has revealed that the addition of magnesium-based additives (MgO) can further optimize the FGT process. During the FGT process (200–300 °C), MgO can adsorb CO2 and, in the subsequent gasification stage (>700 °C), promote CO generation through the reverse Boudouard reaction (RBD), thereby increasing the conversion rate of biochar. Furthermore, MgO catalysts also play a crucial role in promoting tar cracking and enhancing gasification activity. However, existing research primarily focuses on FGT processes with fixed flue gas components (such as N2, CO2, and O2). In industrial applications, flue gas components often vary due to factors such as fuel type and combustion method. These variations affect the physicochemical properties of baked goods and the CO2 adsorption capacity of MgO, thus impacting overall gasification performance. Therefore, it is urgent to investigate the influence mechanism of different flue gas components on the FGT-gasification system (MgO-FGT-GS) with added magnesium-based additives to optimize process parameters and promote its industrial application. Summary of the Invention

[0006] The purpose of this invention is to provide an integrated method for flue gas recirculation biomass roasting-gasification based on magnesium-based additives, in order to solve the above-mentioned technical problems.

[0007] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0008] This invention provides an integrated method for flue gas recirculation biomass roasting-gasification based on magnesium-based additives, comprising the following steps:

[0009] Step 1) After being crushed, ground, and dried, the biomass material enters the flue gas recirculation baking unit and is baked under the action of magnesium-based additives to obtain the first liquid product, the first gaseous product, and the first solid product.

[0010] Step 2) The first solid product obtained and the magnesium-based additive from step 1) enter the integrated gasification unit together, and are gasified under the action of the magnesium-based additive to obtain the second liquid product, the second gaseous product and the second solid product.

[0011] In step 1), in the flue gas recirculation baking unit, the volume fraction of oxygen in the baking atmosphere is controlled to be 8-21%, and the volume fraction of carbon dioxide is controlled to be 5-15%.

[0012] In step 2), the second solid product enters the combustion system, and the resulting flue gas is recycled to the flue gas recirculation baking unit.

[0013] Furthermore, in step 1), the biomass material includes distilled spirits.

[0014] Furthermore, in step 1), the magnesium-based additive includes magnesium oxide.

[0015] Furthermore, in step 1), the baking temperature is 200–300°C.

[0016] Furthermore, in step 1), the mass ratio of the biomass material to the magnesium-based additive is 0.8–1.5:0.5–1.5.

[0017] Furthermore, in step 2), the temperature of vaporization is ≥70℃.

[0018] Furthermore, in step 2), the second gaseous product is used to prepare hydrogen-rich synthesis gas.

[0019] The beneficial effects of this invention are:

[0020] (1) Optimize fuel characteristics and improve gasification performance

[0021] This invention uses optimal flue gas conditions (8% O2, 13% CO2) for baking, which improves the energy density of the fuel, enhances fuel stability, reduces tar formation, and improves the stability of the gasification process.

[0022] By baking pretreatment, the volatile matter (VM) of biomass is reduced to 61.75%–70.05%, resulting in an increase in carbon (FC) to 22.74%–29.56%, optimizing the fuel ratio (FR) to 0.32–0.48, and improving the efficiency and controllability of the gasification reaction.

[0023] Baked products are more stable during gasification, improving gasifier efficiency. Experiments show that baked products exhibit more stable reaction characteristics during gasification, thus improving gasification efficiency. The fixed carbon content (FC) of baked biomass increases to 22.74–29.56%, while the volatile matter (VM) decreases to 61.75–70.05%, helping to reduce tar byproducts and improve gasification reaction stability. The energy density of baked solid fuel increases to 1.22, making it closer to coal fuel than raw biomass, improving biomass fuel utilization efficiency and making it more suitable for industrial gasification reactors.

[0024] (2) Magnesium-based additives enhance the stability of roasted biomass, improve its gasification reaction activity, and improve the quality of syngas.

[0025] The addition of MgO, which also acts as a catalyst, increases the carbon content (C) and decreases the oxygen content (O) of the baked solid products, thereby enhancing the gasification reactivity of the fuel. The alkali metal catalysis also improves the H2 yield.

[0026] MgO has a high CO2 adsorption capacity, and the CO2 adsorption capacity (CR) of MgO-FGT is significantly higher than that of MgO-AT and MgO-NT, which is conducive to the production of hydrogen-rich gas.

[0027] (3) Energy saving and consumption reduction, improving the feasibility of industrial application.

[0028] Due to the effects of baking and the catalytic effect of magnesium-based additives, the activation energy of the cellulose degradation reaction is reduced, which promotes the gasification reaction rate, increases the syngas yield, and thus optimizes the stable operation of the gasifier.

[0029] Using waste heat from flue gas recirculation as a baking heat source reduces external energy demand, lowers operating costs, and improves the economic efficiency of biomass thermochemical conversion.

[0030] The gasification process of roasted charcoal products is more stable, avoiding violent release of volatiles and improving the stability of the gasifier, making this technology have good potential for industrial-scale promotion.

[0031] (4) This technology provides a new approach for the industrial application of biomass clean energy, saving energy and reducing consumption, and improving the feasibility of industrialization.

[0032] Using flue gas recirculation as the baking heat source reduces external energy demand and lowers operating costs.

[0033] By controlling flue gas composition and optimizing biomass pyrolysis kinetics, the yield and calorific value of hydrogen-rich syngas were improved. Adjusting the O2 content of the fuel gas (FG) optimized the degree of biomass pyrolysis, increasing the fuel ratio (FR) to 0.32–0.48, indicating that roasting can significantly improve fuel performance.

[0034] By optimizing the roasting and gasification processes through adjusting the flue gas composition, thermal conversion efficiency is improved, the generation of byproducts during gasification is reduced, and the usability of gaseous fuels is enhanced. Using this method, the LHV of the gasified gas is increased to 19.15 MJ / kg, and the gas quality is significantly optimized, making it suitable for applications in synthetic fuels, chemical production, and other fields. Attached Figure Description

[0035] Figure 1 This is a process route diagram of the integrated method for flue gas recirculation biomass roasting-gasification based on magnesium-based additives, as described in this invention.

[0036] Figure 2 Thermogravimetric analysis (TGA) graphs of the baked products obtained in Examples 1-2 and Comparative Example 2 are shown.

[0037] Figure 3 The following are DTG analysis chromatograms of the baked products obtained in Examples 1-2 and Comparative Example 2;

[0038] Figure 4 Approximate analytical diagrams of untreated distillers' grains (R-DSL) and the roasted products obtained in Examples 1-3 and Comparative Example 2;

[0039] Figure 5 A schematic diagram of the fuel ratio of untreated distillers' grains (R-DSL) and the roasted products obtained in Examples 1-3 and Comparative Example 2;

[0040] Figure 6 This is a characterization diagram of the carbon dioxide adsorption rate of the magnesium-based additive in this invention at different temperatures. Detailed Implementation

[0041] This invention provides an integrated method for flue gas recirculation biomass roasting-gasification based on magnesium-based additives, comprising the following steps:

[0042] Step 1) After being crushed, ground, and dried, the biomass material enters the flue gas recirculation baking unit and is baked under the action of magnesium-based additives to obtain the first liquid product, the first gaseous product, and the first solid product.

[0043] Step 2) The first solid product obtained and the magnesium-based additive from step 1) enter the integrated gasification unit together, and are gasified under the action of the magnesium-based additive to obtain the second liquid product, the second gaseous product and the second solid product.

[0044] In step 1), in the flue gas recirculation baking unit, the volume fraction of oxygen in the baking atmosphere is controlled to be 8-21%, and the volume fraction of carbon dioxide is controlled to be 5-15%.

[0045] In step 2), the second solid product enters the combustion system, and the resulting flue gas is recycled to the flue gas recirculation baking unit.

[0046] In this invention, in step 1), the biomass raw material enters the flue gas pyrolysis stage, and the flue gas provides a heat source to pre-treat the biomass.

[0047] In this invention, the flue gas (containing O2, CO2, etc.) generated by the combustion system is used as the baking atmosphere. The concentrations of O2 and CO2 are controlled to avoid excessive oxidation, while the reaction rate is also regulated. By adjusting the O2 content, the volatile matter content of the baking reaction is controlled, increasing the proportion of fixed carbon in the solid fuel, thereby enhancing the gasification reaction performance. Simultaneously, an oxidation reaction occurs in the system, increasing the pretreatment rate and releasing heat during oxidation, thus reducing the consumption of external energy. The flue gas emitted from the system's combustion device is used as the baking atmosphere; this flue gas mainly contains N2, CO2, and O2, which can provide heat and influence the pyrolysis behavior of biomass.

[0048] In this invention, flue gas with different O2 / CO2 ratios is used for baking, and the O2 content is adjusted to control the degree of baking and optimize the elemental composition of solid fuel. Experiments show that increasing the O2 content promotes a decrease in volatile matter (VM) and an increase in fixed carbon (FC). Appropriate amounts of O2 can improve the fuel ratio (FR) and enhance gasification performance.

[0049] In this invention, since the flue gas composition varies due to different raw materials and furnace types, the oxygen content can be adjusted later by adding air as needed.

[0050] In this invention, in step 1), the biomass material includes distilled spirits.

[0051] In this invention, in step 1), the magnesium-based additive includes magnesium oxide.

[0052] In this invention, a magnesium-based additive is introduced during the roasting stage to promote the stability of the internal structure of biomass and improve its subsequent gasification reactivity. During roasting, the magnesium-based additive adsorbs CO2 released from flue gas and biomass, reducing tar formation and increasing the carbon content (C) of the solid products. The adsorbed CO2 is released during gasification and undergoes a reverse Boudouard reaction with the charcoal (C + CO2 → 2CO), promoting CO formation and increasing the calorific value (LHV) of the gaseous fuel.

[0053] In this invention, in step 1), the baking temperature is 200-300°C, preferably 220-280°C.

[0054] In this invention, the roasting process primarily decomposes hemicellulose, reducing the oxygen content of biomass. This deep degradation of cellulose increases fixed carbon content and optimizes the fuel structure.

[0055] In this invention, in step 1), the mass ratio of the biomass material to the magnesium-based additive is 0.8-1.5:0.5-1.5.

[0056] In this invention, in step 2), the temperature of vaporization is ≥70℃, preferably ≥80℃.

[0057] In this invention, the roasted biomass, in conjunction with magnesium-based additives during the gasification stage, accelerates the degradation of pyrolysis tar, increases H2 yield, and reduces byproducts such as CO and CH4. While CO2 can act as a gasifying agent during gasification, promoting CO generation, excessively high CO2 concentrations may reduce H2 production. Therefore, this invention optimizes the gas composition by rationally controlling the CO2 content in the roasted flue gas. Studies have shown that magnesium-based additives can adsorb CO2 during roasting and release it as a gasifying agent during the gasification stage. Appropriate CO2 adsorption enhances the catalytic effect of magnesium-based additives, making the H2 content in the syngas controllable and achieving efficient fuel gas production.

[0058] In this invention, in step 2), the second gaseous product is used to prepare hydrogen-rich synthesis gas.

[0059] In this invention, magnesium oxide (99% purity) was purchased from Aladdin Chemical Reagent Co., Ltd. in Shanghai, China.

[0060] In this invention, roasted biomass, in conjunction with magnesium-based additives during the gasification stage, accelerates the degradation of pyrolysis tar, increases H2 yield, and reduces byproducts such as CO and CH4. A self-gasification mode is employed, allowing the gasification reaction to proceed in a controlled manner. The CO2 carried by magnesium oxide reduces the influence of external gas supply and N2, improving system thermal efficiency and economy. Thermogravimetric-Fourier transform infrared spectroscopy (TG-MS-FTIR) is used to quantitatively analyze the release patterns of biomass decomposition products during roasting-gasification, optimizing gasification parameters. Part of the roasted product is used for gasification experiments, and part is used for TG-MS-FTIR analysis. To ensure the normal operation of the online gas analyzer (Gasboard-3100 from Ruiyi Automation, non-dispersive infrared absorption method), the N2 flow rate is adjusted to 800 mL / min. This gas analyzer can simultaneously measure CO, CO2, CH4, H2, and C. n H m Its low heating value and volume concentration enable real-time monitoring and analysis of gaseous products.

[0061] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0062] Example 1

[0063] Distilled grains (DSL) were crushed and ground using a cutter, with the particle size controlled below 400 μm. The ground DSL was then dried at 105°C for 24 hours and stored in a desiccator.

[0064] Distilled grains enter the flue gas roasting unit, where flue gas (roasting atmosphere: 8 vol% O2, 13 vol% CO2, 79 vol% N2) is introduced. Under the influence of an equal mass of magnesium oxide, roasting is carried out at 250°C to obtain the roasted product, denoted as MgO-FGT. The resulting roasted products are a first liquid product, a first gaseous product, and a first solid product. The resulting solid product, along with the magnesium oxide, is then fed into an integrated gasification unit. Under the influence of magnesium oxide, gasification occurs at 800°C to obtain the gasification products, which are a second liquid product, a second gaseous product, and a second solid product. The second gaseous product is used to prepare hydrogen-rich syngas, and the combustion heat energy of the second solid product is used for system heating and power generation. Waste heat is recycled, and the flue gas produced from combustion is optimized and its composition and proportions adjusted before being reused in the flue gas roasting unit.

[0065] Example 2

[0066] Unlike Example 1, in this example, flue gas and air with a volume ratio of 1:1 are introduced into the flue gas baking unit, and the baking atmosphere composition is 14.5 vol% O2, 6.5 vol% CO2, and 79 vol% N2. The resulting baking product is denoted as MgO-FAT.

[0067] Example 3

[0068] Unlike Example 1, in this example, air is introduced into the flue gas baking unit, and the baking atmosphere composition is 21 vol% O2 and 79 vol% N2. The resulting baked product is denoted as MgO-AT.

[0069] Comparative Example 1

[0070] Unlike Example 1, in this comparative example, no magnesium oxide was added during the process, and the resulting baked product was denoted as FGT.

[0071] Comparative Example 2

[0072] Unlike Example 1, in this comparative example, nitrogen gas was introduced into the flue gas baking unit, i.e., the baking atmosphere composition was 100 vol% N2, and the resulting baking product was denoted as MgO-NT.

[0073] Table 1 shows some process parameters for Examples 1-3 and Comparative Examples 1-2.

[0074] Table 1. Partial process parameters of Examples 1-3 and Comparative Examples 1-2

[0075]

[0076]

[0077] Characteristic analysis of the baked products obtained in Examples 1-3 and Comparative Examples 1-2: Industrial and elemental analysis was performed using a muffle furnace and elemental analyzer. Thermochemical behavior and kinetic properties were evaluated using TG-MS-FTIR technology. In the TG-MS-FTIR experiment, the temperature was gradually increased from 50°C to 900°C at a rate of 10°C / min to analyze the thermochemical behavior, and the released substances were detected online using MS and FTIR.

[0078] Table 2 shows the elemental analysis and high calorific value data characterization of untreated distillers' grains (R-DSL) and baked products.

[0079] Table 2. Elemental analysis and high-calorific-value data characterization of untreated distillers' grains (R-DSL) and baked goods.

[0080]

[0081] Table 2 shows that the CR (Reduction Capacity) from highest to lowest is MgO-FGT, MgO-FAT, MgO-AT, and MgO-NT. The CR values ​​of MgO-AT and MgO-NT reveal the effectiveness of magnesium additives in absorbing carbon dioxide released from the biomass during roasting (DSL). Furthermore, the high CR values ​​of MgO-FGT and MgO-FAT demonstrate that magnesium additives can absorb carbon dioxide from the fuel gas (FG). The higher carbon dioxide content in FG facilitates better carbon dioxide absorption by magnesium additives, potentially providing a better gasifying agent for gasification. Additionally, roasting reduces the H and O content in biomass while increasing the C content. As the O2 content in the flue gas increases, the C content gradually increases, while the O and H content gradually decreases. The MgO-FGT product exhibits higher C and H content, indicating that an appropriate O2 content in the flue gas required for industrial production can better improve fuel characteristics.

[0082] Figure 1 This is a process route diagram of the integrated flue gas recirculation biomass roasting-gasification method based on magnesium-based additives, as described in this invention. As shown in the diagram, the biomass feedstock enters the flue gas pyrolysis (FGT) stage, where the flue gas provides a heat source for pretreatment of the biomass. Magnesium oxide (MgO) is added during roasting; the MgO captures carbon dioxide and, after pyrolysis, yields the roasted product. During the gasification stage of the roasted product, reverse Boudouard (RBD) mainly occurs, resulting in the formation of carbon monoxide. The formation of carbon monoxide increases the coke conversion rate. The increased coke conversion rate ultimately improves the quality of the syngas.

[0083] Figure 2 The thermogravimetric analysis (TG) curves of the baked products obtained in Examples 1-2 and Comparative Example 2 are shown. The TG curves indicate that after weight loss begins at 160°C, the residual mass of the MgO-FGT product is higher than that of the MgO-NT product. Furthermore, quantitative assessment of thermal stability using indicators reveals that the D value of the MgO-FGT product (3.34 × 10⁻⁶) is significantly lower. -6 The concentration was lower than that of MgO-NT products (5.02 × 10⁻⁶). -6 This indicates that MgO-FGT has a better thermal stability effect on biomass (such as distiller's grains). Furthermore, the high O2 content in the flue gas, as seen in MgO-FAT, is beneficial for achieving superior thermal stability in roasted products.

[0084] Figure 3The following are the micro-quotient thermogravimetric analysis (DTG) curves of the roasted products obtained in Examples 1-2 and Comparative Example 2. Analysis of the micro-quotient DTG curves shows that MgO-FGT enriches lignin and promotes the decomposition of hemicellulose and cellulose. Specifically, the DTG peaks of hemicellulose and cellulose in the MgO-NT product reach their maximum values, while the peaks of the MgO-FAT product are the minimum, and the DTG peak of lignin shows the opposite trend. This helps improve the fuel characteristics of biomass and provides a higher quality feedstock for subsequent gasification processes. In summary, the MgO-FGT product exhibits better thermal stability and superior fuel performance, laying the foundation for the efficient implementation of the integrated biomass roasting-gasification process and potentially improving the performance and product quality of the entire integrated system.

[0085] Figure 4 Approximate analytical diagrams are shown for untreated distillers' grains (R-DSL) and the roasted products obtained in Examples 1-3 and Comparative Example 2. As can be seen from the diagrams, after roasting the untreated distillers' grains (R-DSL), the volatile matter (VM, i.e., Figure 4 The content of volatile matter decreased from 75.10% to 61.75-70.05%, and the fixed carbon (FC, i.e., Figure 4 The fixed carbon (FC) content increased from 14.56% to 22.74-29.56%. High FC content can increase CO production during gasification, while low VM content helps reduce tar formation, resulting in better performance of roasted products during gasification. As the O2 content in the flue gas increases, the VM content gradually decreases, while the FC content gradually increases, enhancing the release of volatiles and the thermal degradation process.

[0086] Figure 5 The graph shows the fuel ratio (FR) curves for untreated distillers' grains (R-DSL) and the roasted products obtained in Examples 1-3 and Comparative Example 2. As can be seen from the graph, compared to R-DSL, the FR increased from a lower value to 0.32-0.48 after roasting, and the FR gradually increased with increasing O2 content, indicating that roasting improved fuel characteristics, and oxidative roasting (such as in cases with higher O2 content) may result in better gasification performance.

[0087] Figure 6This is a characterization graph of the carbon dioxide adsorption rate of the magnesium-based additives in this invention at different temperatures. The CO2 adsorption rate (CR) is used to evaluate the adsorption capacity of the magnesium-based additives. As shown in Table 2, the CR values ​​of MgO-FGT, MgO-FAT, MgO-AT, and MgO-NT are arranged from high to low. The CR values ​​of MgO-AT and MgO-NT indicate the adsorption effect of magnesium oxide on CO2 released by DSL during the baking process. The high CR values ​​of MgO-FGT and MgO-FAT indicate that magnesium oxide has a strong adsorption capacity for CO2 in the flue gas. A higher CO2 content in the flue gas helps magnesium oxide absorb more CO2, providing more gasifying agent for gasification.

[0088] As demonstrated by the above embodiments, this invention provides an integrated method for biomass roasting and gasification based on magnesium-based additives. By altering the O2 content in the flue gas, this invention significantly affects the industrial analytical characteristics (VM, FC content changes), fuel ratio, and elemental composition of the roasted biomass products, fully demonstrating that the performance of roasted biomass products can be directionally optimized by controlling the flue gas composition. Furthermore, by regulating the catalytic effect of magnesium-based additives, this invention improves the fuel quality of the roasted products and enhances the reactivity of biomass during gasification, thereby increasing the yield and quality of hydrogen-rich syngas and providing technical support for the industrial application of biomass thermochemical conversion.

[0089] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for integrated biomass roasting-gasification based on magnesium-based additives and flue gas recirculation, characterized in that, Includes the following steps: Step 1) After being crushed, ground, and dried, the biomass material enters the flue gas recirculation baking unit and is baked under the action of magnesium-based additives to obtain the first liquid product, the first gaseous product, and the first solid product. Step 2) The first solid product obtained and the magnesium-based additive from step 1) enter the integrated gasification unit together, and are gasified under the action of the magnesium-based additive to obtain the second liquid product, the second gaseous product and the second solid product. In step 1), in the flue gas recirculation baking unit, the volume fraction of oxygen in the baking atmosphere is controlled to be 8-21%, and the volume fraction of carbon dioxide is controlled to be 5-15%. In step 2), the second solid product enters the combustion system, and the resulting flue gas is recycled to the flue gas recirculation baking unit. In step 1), the magnesium-based additive includes magnesium oxide; In step 1), the mass ratio of the biomass material to the magnesium-based additive is 0.8~1.5:0.5~1.

5.

2. The integrated method for flue gas recirculation biomass roasting-gasification based on magnesium-based additives as described in claim 1, characterized in that, In step 1), the biomass material includes distilled spirits.

3. The integrated method for flue gas recirculation biomass roasting-gasification based on magnesium-based additives as described in claim 2, characterized in that, In step 1), the baking temperature is 200~300℃.

4. A method for integrated flue gas recirculation biomass roasting-gasification based on magnesium-based additives, as described in claim 2 or 3, characterized in that, In step 2), the temperature of vaporization is ≥70℃.

5. The integrated method for flue gas recirculation biomass roasting-gasification based on magnesium-based additives as described in claim 4, characterized in that, In step 2), the second gaseous product is used to prepare hydrogen-rich synthesis gas.

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