Flue gas circulation biomass baking-gasification integrated method based on magnesium-based additive reinforcement

Abstract

The invention provides a flue gas circulation biomass baking-gasification integrated method based on magnesium-based additive reinforcement, and belongs to the technical field of biomass energy. According to the method, by optimizing the synergistic effect of flue gas circulation components and magnesium-based additives, the fuel quality of biomass baking products is improved, in-situ CO2 gasification is achieved, the gasification reaction activity is enhanced through alkali metal catalysis, and then the gasification reaction process is optimized. The technology has the capabilities of improving the gasification stability of the biomass fuel, optimizing the quality of gasified synthesis gas and reducing the generation of tar byproducts, and the adsorption characteristic of magnesium oxide is utilized to capture CO2 and improve the quality of the gasified synthesis gas while the flue gas waste heat is efficiently utilized to bake the biomass to improve the energy density of the fuel, so that the thermochemical conversion efficiency of the biomass is improved. The problems of high tar byproduct content, low gasification efficiency, unstable gas product quality and the like in the traditional biomass gasification process are solved to a certain extent, and a new technical path is provided for industrial application.

Description

Technical Field

[0001] The present invention relates to the technical field of biomass energy, and particularly to an integrated method for flue gas circulation biomass torrefaction-gasification enhanced by a magnesium-based additive. Background Art

[0002] The problem of global warming is intensifying day by day. Since the Industrial Revolution, the global temperature has risen by more than 1°C, mainly due to the increase in atmospheric CO2 concentration caused by the combustion of fossil fuels. To address this challenge, biomass, as a renewable energy source, has attracted much attention. Its rich reserves and carbon-neutral characteristics make it an important alternative to fossil fuels.

[0003] Gasification technology is an important path for the resource utilization of biomass, with wide raw material adaptability and flexible gas production capacity. However, biomass naturally has problems such as high oxygen content and low energy density, making it difficult to achieve economic feasibility in direct gasification. Therefore, appropriate pretreatment before gasification is crucial for improving the performance of biomass fuels.

[0004] In recent years, torrefaction pretreatment has been considered an effective method to improve gasification efficiency because it can improve the characteristics of biomass fuels, reduce the O / C ratio, increase the energy density and the higher heating value (HHV). Research shows that torrefied biomass exhibits higher H2 and CO yields during the gasification process. However, traditional torrefaction technologies usually use inert atmospheres such as N2 or CO2, resulting in high costs and the underutilization of flue gas waste heat resources. Therefore, the flue gas-based torrefaction technology (FGT) has become a research hotspot in recent years. This method uses flue gas as a heat source and atmosphere to further improve the gasification performance of biomass torrefaction products.

[0005] On this basis, it has been found that adding a magnesium-based additive (MgO) can further optimize the FGT process. During the FGT process (200 - 300°C), MgO can adsorb CO2 and promote CO generation through the reverse Boudouard reaction (RBD) during the subsequent gasification stage (>700°C), improving the conversion rate of biomass char. In addition, the MgO catalyst also plays an important role in promoting tar cracking and enhancing gasification activity. However, existing research mainly focuses on the FGT process with fixed flue gas components (such as N2, CO2, O2), while in industrial applications, flue gas components often change due to factors such as fuel type and combustion mode. This change will affect the physical and chemical properties of the torrefaction products and the CO2 adsorption capacity of MgO, thus affecting the overall gasification performance. Therefore, it is urgent to study the influence mechanism of different flue gas components on the FGT-gasification system (MgO-FGT-GS) with a magnesium-based additive to optimize the process parameters and promote its industrial application. Summary of the Invention

[0006] The object of the present invention is to provide a method for integrated flue gas circulation biomass baking and gasification enhanced by a magnesium-based additive to solve the above technical problems.

[0007] To achieve the above object of the invention, the present invention provides the following technical solutions:

[0008] The present invention provides a method for integrated flue gas circulation biomass baking and gasification enhanced by a magnesium-based additive, comprising the following steps:

[0009] Step 1), the biomass material is crushed, ground and dried and then enters the flue gas circulation baking unit, and is baked under the action of the magnesium-based additive to obtain a first liquid product, a first gas product and a first solid product respectively;

[0010] Step 2), the obtained first solid product and the magnesium-based additive in Step 1) jointly enter the integrated gasification unit and are gasified under the action of the magnesium-based additive to obtain a second liquid product, a second gas product and a second solid product;

[0011] In Step 1), in the flue gas circulation 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 5-15%;

[0012] In Step 2), the second solid product enters the combustion system, and the obtained flue gas is recycled to the flue gas circulation baking unit.

[0013] Further, in Step 1), the biomass material includes distiller's grains.

[0014] Further, in Step 1), the magnesium-based additive includes magnesium oxide.

[0015] Further, in Step 1), the temperature of the baking treatment is 200-300 °C.

[0016] Further, 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] Further, in Step 2), the temperature of the gasification is ≥70 °C.

[0018] Further, in Step 2), the second gas product is used to prepare hydrogen-rich syngas.

[0019] The beneficial effects of the present invention:

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

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

[0022] Through baking pretreatment, the volatile matter (VM) of biomass is reduced to 61.75% - 70.05%, enabling the fixed carbon (FC) to be increased 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] The baked product is more stable during the gasification process, improving the gasifier efficiency. Experiments show that the baked product exhibits more stable reaction characteristics during gasification, improving the gasification efficiency. The fixed carbon content (FC) of the baked biomass is increased to 22.74 - 29.56%, while the volatile matter (VM) is reduced to 61.75 - 70.05%, which helps to reduce tar by-products and improve the stability of the gasification reaction. The energy density of the baked solid fuel is increased to 1.22, making it closer to coal fuel compared to the original biomass, improving the utilization efficiency of biomass fuel and making it more suitable for industrial gasification reactors.

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

[0025] Adding MgO also acts as a catalyst, increasing the carbon content (C) of the baked solid product while reducing the oxygen content (O), enhancing the gasification reactivity of the fuel, and the alkali metal catalytic effect increases 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 helps in the production of hydrogen-rich gas.

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

[0028] Due to the influence of baking and the catalytic effect of magnesium-based additives, the activation energy of the cellulose degradation reaction is reduced, promoting the gasification reaction rate, increasing the syngas yield, and thus optimizing the stable operation of the gasifier.

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

[0030] The reaction of the baked carbon product during gasification is more stable, avoiding violent volatile matter release, improving the stability of the gasifier, and making this technology have good promotion potential on an industrial scale.

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

[0032] The use of flue gas circulation as the baking heat source reduces external energy demand and lowers operating costs.

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

[0034] By adjusting the flue gas composition, the roasting and gasification processes are optimized, increasing thermal conversion efficiency, reducing by-product formation during gasification, and enhancing the usability of the gaseous fuel. This method increases the LHV of the gasified gas to 19.15 MJ / kg, significantly improving gas quality and making it suitable for applications such as synthetic fuels and chemical production. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 The process roadmap of the integrated biomass roasting-gasification method based on flue gas circulation enhanced by magnesium-based additives of the present invention is as follows;

[0036] Figure 2 Thermogravimetric analysis diagrams of the baked products obtained in Examples 1-2 and Comparative Example 2;

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

[0038] Figure 4 The approximate analysis diagrams of untreated wine lees (R-DSL) and the baked products obtained in Examples 1 to 3 and Comparative Example 2;

[0039] Figure 5 Schematic diagram of the fuel ratio of untreated distillers grains (R-DSL) and the roasted products obtained in Examples 1 to 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 the present invention at different temperatures. DETAILED DESCRIPTION

[0041] The present invention provides an integrated method for biomass roasting and gasification based on flue gas circulation enhanced by magnesium-based additives, comprising the following steps:

[0042] Step 1), after being crushed, ground and dried, the biomass material enters a flue gas circulation baking unit and is baked under the action of a magnesium-based additive to obtain a first liquid product, a first gas product and a first solid product respectively;

[0043] Step 2): The obtained first solid product and the magnesium-based additive in Step 1) jointly enter the integrated gasification unit, and are gasified under the action of the magnesium-based additive to obtain a second liquid product, a second gas product and a second solid product;

[0044] In Step 1), in the flue gas circulation 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 5-15%;

[0045] In Step 2), the second solid product enters the combustion system, and the obtained flue gas is recycled to the flue gas circulation baking unit.

[0046] In the present invention, in Step 1), the biomass raw material enters the flue gas pyrolysis stage, and the flue gas provides heat source for pre-treating the biomass.

[0047] In the present invention, the flue gas (containing O2, CO2, etc.) generated by the combustion system is used as the baking atmosphere, and the O2 and CO2 concentration contents are controlled to avoid over-oxidation, and at the same time, the reaction rate is regulated. By adjusting the O2 content, the volatile matter degree of the baking reaction is controlled, the proportion of fixed carbon in the solid fuel is increased, thereby enhancing the gasification reaction performance. At the same time, an oxidation reaction occurs in the system, the pre-treatment rate is increased, and heat is released by oxidation, reducing the external energy consumption. Using the flue gas discharged from the system combustion device as the baking atmosphere, the flue gas mainly contains N2, CO2 and O2, which can provide heat and affect the pyrolysis behavior of biomass.

[0048] In the present invention, baking is carried out with flue gas of different O2 / CO2 ratios, and the O2 content is adjusted to control the baking degree and optimize the elemental composition of the solid fuel. Experiments show that an increase in the O2 content will promote a decrease in volatile matter (VM) and an increase in fixed carbon (FC). An appropriate amount of O2 can increase the fuel ratio (FR) and improve the gasification performance.

[0049] In the present invention, due to the difference in the flue gas components generated by different raw materials, furnace types, etc., air can be adjusted according to needs to adjust the oxygen content in the later stage.

[0050] In the present invention, in Step 1), the biomass material includes distiller's grains.

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

[0052] In the present invention, a magnesium-based additive is introduced in the baking stage to promote the stability of the internal structure of biomass and improve the subsequent gasification reactivity. The magnesium-based additive can adsorb the CO2 released from the flue gas and biomass during the baking process, reduce tar formation, and increase the carbon content (C) of the solid product. The adsorbed CO2 is released during the gasification process and undergoes an inverse Boudouard reaction (C + CO2 → 2CO) with the carbon, promoting CO generation and increasing the calorific value (LHV) of the gaseous fuel.

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

[0054] In the present invention, during the baking process, hemicellulose is mainly decomposed to reduce the oxygen content of biomass. Cellulose is deeply degraded to increase the fixed carbon content and optimize the fuel structure.

[0055] In the present 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 the present invention, in step 2), the temperature of the gasification is ≥70 °C, preferably ≥80 °C.

[0057] In the present invention, the baked biomass acts together with the magnesium-based additive in the gasification stage to accelerate the cracking and degradation of tar, increase the H2 yield, and reduce by-products such as CO and CH4. CO2 can act as a gasifying agent during the gasification process to promote the generation of CO, but too high a CO2 concentration may reduce the H2 output. Therefore, in the present invention, by reasonably controlling the CO2 content in the flue gas baking, the gas components are optimized. Research shows that the magnesium-based additive can adsorb CO2 during the baking process and release CO2 as a gasifying agent during the gasification stage. Appropriate adsorption of CO2 can improve the catalytic effect of the magnesium-based additive, make the H2 content in the syngas controllable, and achieve efficient fuel gas production.

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

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

[0060] In the present invention, the baked biomass acts together with the magnesium-based additive in the gasification stage to accelerate the cracking and degradation of tar, increase the H2 yield, and reduce by-products such as CO and CH4. The self-gasification mode is adopted to control the gasification reaction. The CO2 carried by magnesium oxide reduces the influence of external gas supply and N2, improving the system thermal efficiency and economy. Combining the thermogravimetry-Fourier transform infrared spectroscopy (TG-MS-FTIR) analysis method, the release law of biomass decomposition products during the baking-gasification process is quantitatively analyzed to optimize the gasification parameters. The obtained baked products are partly used for gasification experiments and partly for TG-MS-FTIR analysis. To ensure the normal operation of the on-line gas analyzer (Gasboard-3100 of Ruiyi Automatic Control Company, non-dispersive infrared absorption method), the N2 flow rate is adjusted to 800 mL / min. This gas analyzer can simultaneously measure the lower calorific value and volume concentration of CO, CO2, CH4, H2, and C n H m and can monitor and analyze the gas products in real time.

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

[0062] Example 1

[0063] Distillers' spent grains with liquid (DSL) are crushed and ground by a cutting machine, and the particle size is controlled below 400 μm. The ground DSL is dried at 105 °C for 24 hours and stored in a dryer.

[0064] The distillers' spent grains with liquid enter the flue gas baking unit, and flue gas (the baking atmosphere is 8 vol% O2, 13 vol% CO2, 79 vol% N2) is introduced. Under the action of the same mass of magnesium oxide, baking treatment is carried out at 250 °C to obtain a baked product, denoted as MgO-FGT. The obtained baked products are the first liquid product, the first gas product, and the first solid product respectively. Then, the obtained solid product and magnesium oxide are sent into the integrated gasification unit together. Under the action of magnesium oxide, gasification is carried out at 800 °C to obtain gasification products, which are the second liquid product, the second gas product, and the second solid product respectively. Among them, the second gas product is used to prepare hydrogen-rich syngas, the combustion heat energy of the second solid product is used for system heat supply and power generation, and the waste heat is recycled. The flue gas generated by combustion is reused in the flue gas baking unit after optimizing the composition and ratio.

[0065] Example 2

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

[0067] Example 3

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

[0069] Comparative Example 1

[0070] Different from Example 1, in this comparative example, magnesium oxide was not added in the process, and the obtained baking product was denoted as FGT.

[0071] Comparative Example 2

[0072] Different from Example 1, in this comparative example, nitrogen was introduced into the flue gas baking unit, that is, the baking atmosphere composition was 100 vol% N2, and the obtained baking product was denoted as MgO-NT.

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

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

[0075]

[0076]

[0077] Analysis of the characteristics of the baking products obtained in Examples 1-3 and Comparative Examples 1-2: Industrial analysis and elemental analysis were carried out using a muffle furnace and an elemental analyzer. The thermochemical behavior and kinetic characteristics were evaluated by 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 by MS and FTIR.

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

[0079] Table 2 Data characterization of elemental analysis and high calorific value of untreated distillers' grains (R-DSL) and baking products

[0080]

[0081] As can be seen from Table 2, the order of CR from high to low is MgO-FGT, MgO-FAT, MgO-AT, and MgO-NT. The CR of MgO-AT and MgO-NT reveals the effectiveness of magnesium additives in absorbing the carbon dioxide released by DSL during the absorption baking process. In addition, the high CR of MgO-FGT and MgO-FAT proves that magnesium additives can absorb carbon dioxide in FG. The higher carbon dioxide content in FG is conducive to the better absorption of carbon dioxide by magnesium additives, which may provide a better gasifying agent for gasification. Additionally, baking reduces the contents of H and O in biomass and increases the content of C. As the O2 content in the flue gas increases, the C content gradually increases, while the O and H contents gradually decrease. The MgO-FGT product has relatively high C and H contents, indicating that an appropriate O2 content in the flue gas required for industrial production can better improve the fuel characteristics.

[0082] Figure 1 This is the process flow diagram of the integrated method for magnesium-based additive enhanced flue gas circulating biomass baking-gasification of the present invention. As can be seen from the figure, the biomass raw material enters the flue gas pyrolysis (FGT) stage, where the flue gas provides heat source for the pretreatment of biomass. Magnesium oxide (MgO) is added during the baking process, and MgO captures carbon dioxide, and the baked product is obtained after pyrolysis. In the gasification stage of the baked product, the reverse Boudouard (RBD) mainly occurs, resulting in the reaction to generate carbon monoxide, and the generation of carbon monoxide improves the coke conversion rate. The improvement of the coke conversion rate ultimately enhances the quality of the syngas.

[0083] Figure 2 This is the thermogravimetric analysis diagram of the baked products obtained in Examples 1-2 and Comparative Example 2. From the thermogravimetric (TG) curve, it can be seen that after the weight loss starts at 160 °C, the residual mass of the MgO-FGT product is higher than that of the MgO-NT product. And through quantitative evaluation of the thermal stability by indicators, it is found that the D value (3.34×10 -6 ) of the MgO-FGT product is lower than that of the MgO-NT product (5.02×10 -6 ), indicating that MgO-FGT has a better thermal stability effect on biomass (such as distiller's grains). In addition, in the case of high O2 content in the flue gas like MgO-FAT, it is beneficial for the baked product to obtain more excellent thermal stability.

[0084] Figure 3The differential thermogravimetric analysis graphs of the baking products obtained in Examples 1 to 2 and Comparative Example 2. From the analysis of the differential thermogravimetric (DTG) curve, it can be seen that MgO-FGT enriches lignin and promotes the decomposition of hemicellulose and cellulose. Specifically, the DTG peaks of hemicellulose and cellulose of the MgO-NT product reach the maximum value, the peak of the MgO-FAT product is the smallest, and the DTG peak of lignin shows the opposite trend. This helps to improve the fuel properties of biomass and provide better raw materials for the subsequent gasification process. Based on the TG-DTG analysis results, the MgO-FGT product exhibits better thermal stability and more superior fuel performance, which lays the foundation for the efficient implementation of the biomass baking-gasification integrated process, and is expected to improve the performance and product quality of the entire integrated system.

[0085] Figure 4 The figure shows the approximate analysis of the untreated vinasse (R-DSL) and the baked products obtained in Examples 1 to 3 and Comparative Example 2. As can be seen from the figure, after baking the untreated vinasse (R-DSL), the volatile matter (VM, i.e. Figure 4 Volatile matter content decreased from 75.10% to 61.75-70.05%, and fixed carbon (FC, i.e. Figure 4 The fixed carbon (FC) content increased from 14.56% to 22.74-29.56%. High FC content increases CO production during gasification, while low VM content helps reduce tar formation, resulting in better gasification performance for the baked product. As the O2 content in the flue gas increases, the VM content gradually decreases and the FC content gradually increases, enhancing the volatile matter release and thermal degradation process.

[0086] Figure 5 The figure shows the fuel ratio of untreated distillers grains (R-DSL) and the torrefied products obtained in Examples 1-3 and Comparative Example 2. As shown in the figure, compared with R-DSL, the FR increases from a lower value to 0.32-0.48 after torrefaction, and the FR gradually increases with increasing O2 content, indicating that torrefaction improves fuel properties and that oxidative torrefaction (e.g., with higher O2 content) may lead to better gasification performance.

[0087] Figure 6This is the characterization diagram of the CO2 adsorption rate of the magnesium-based additive in the present invention at different temperatures. The CO2 adsorption rate (CR) is used to evaluate the adsorption capacity of the magnesium-based additive. Combining Table 2, it can be seen that the CR of MgO-FGT, MgO-FAT, MgO-AT, and MgO-NT are arranged from high to low. The CR of MgO-AT and MgO-NT shows the adsorption effect of magnesium oxide on the CO2 released by DSL during the baking process, and the high CR of MgO-FGT and MgO-FAT indicates that magnesium oxide has a strong adsorption capacity for CO2 in flue gas. The higher CO2 content in the flue gas helps magnesium oxide absorb more CO2 and provides more gasifying agents for gasification.

[0088] As can be seen from the above embodiments, the present invention provides a method for integrated flue gas circulation biomass baking and gasification based on magnesium-based additives. By changing the O2 content in the flue gas, the present invention can significantly affect the proximate analysis characteristics (changes in VM and FC content), fuel ratio, and elemental composition of biomass baking products, fully demonstrating that the performance of biomass baking products can be directionally optimized by regulating the flue gas components. By regulating the catalytic effect of the magnesium-based additive, the present invention improves the fuel quality of the baking products, enhances the reactivity of biomass during the gasification process, 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 are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A method for integrated flue gas circulation biomass baking and gasification strengthened by magnesium-based additives, characterized in that, It includes the following steps: Step 1): The biomass material is crushed, ground, and dried and then enters the flue gas circulation baking unit, where baking treatment is carried out under the action of a magnesium-based additive to obtain a first liquid product, a first gas product, and a first solid product respectively; Step 2): The obtained first solid product and the magnesium-based additive in Step 1) jointly enter the integrated gasification unit, where gasification is carried out under the action of the magnesium-based additive to obtain a second liquid product, a second gas product, and a second solid product; In Step 1), in the flue gas circulation 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 5-15%; In Step 2), the second solid product enters the combustion system, and the obtained flue gas is recycled to the flue gas circulation baking unit.

2. A method for integrated biomass baking and gasification with enhanced flue gas circulation based on a magnesium-based additive as claimed in claim 1, wherein In Step 1), the biomass material includes distiller's grains.

3. A method for integrated flue gas circulation biomass baking-gasification enhanced by a magnesium-based additive according to claim 1 or 2, characterized in that In Step 1), the magnesium-based additive includes magnesium oxide.

4. A method for integrated flue gas circulation biomass baking and gasification enhanced by a magnesium-based additive according to claim 3, characterized in that, In Step 1), the temperature of the baking treatment is 200-300 °C.

5. A method for integrated biomass baking and gasification with flue gas circulation enhanced by a magnesium-based additive according to claim 4, characterized in that In Step 1), the mass ratio of the biomass material to the magnesium-based additive is 0.8-1.5:0.5-1.

5.

6. A method for integrated flue gas circulation biomass baking-gasification enhanced by a magnesium-based additive according to claim 4 or 5, characterized in that, In Step 2), the temperature of the gasification is ≥70 °C.

7. A method for integrated flue gas circulation biomass baking and gasification enhanced by a magnesium-based additive according to claim 6, characterized in that In Step 2), the second gas product is used to prepare hydrogen-rich syngas.

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