Method for capturing and converting carbon dioxide after biomass gasification

Abstract

The invention discloses a method for capturing and converting carbon dioxide after biomass gasification, which comprises the following steps: in the gasification process, capturing carbon dioxide in gas through selective catalytic reaction, and guiding to a carbon dioxide absorption system, the absorption system adopts a chemical adsorption method, the capturing rate is not less than 90%, and the conversion rate is not less than 90%; a carbon dioxide absorption system is used for converting captured carbon dioxide into an available by-product, the by-product is carbonate, the conversion rate reaches 85% or above, combustible gas generated through gasification is conveyed to a power generation device, combustion is conducted under the condition that the temperature ranges from 300 DEG C to 500 DEG C, and a power generation unit is driven to generate power. Thus, it is possible to improve power generation efficiency and reduce greenhouse gas emissions by capturing and converting carbon dioxide into an available by-product during gasification, the problem of carbon dioxide emissions is solved by a specific catalyst and a carbon dioxide conversion system, and this method not only improves gasification efficiency but also achieves the goal of environmental protection.

Description

Technical Field

[0001] The present invention relates to the technical field of biomass power generation, and in particular to a method for capturing and converting carbon dioxide after biomass gasification. Background Art

[0002] At present, biomass gas power generation technology is widely used in the field of energy conversion. Biomass gasification is a process that converts biomass raw materials into combustible gases through pyrolysis and gasification reactions. These gases can be used as fuel to drive generator sets to generate electricity. The gasification process is usually carried out at high temperatures, and oxygen or steam is used to react with biomass raw materials. The generated gas can be used to generate electricity. At the same time, traditional biomass gas power generation technology mostly relies on catalysts and combustion devices to improve gasification efficiency and power generation efficiency. In recent years, with the improvement of environmental protection requirements, researchers have gradually paid attention to how to reduce the emission of greenhouse gases such as carbon dioxide during the gasification process, and seek effective carbon dioxide capture and conversion technology; However, existing technologies often emit a large amount of carbon dioxide during the gasification process, and this carbon dioxide is difficult to be effectively captured and converted during the gasification process, thus causing greater environmental pollution. In addition, traditional methods for capturing and converting carbon dioxide after biomass gasification usually only focus on improving gas production and calorific value, and there is no effective solution for the capture efficiency and conversion efficiency of carbon dioxide. The shortcomings of these technologies not only limit the environmental performance of gas-powered power generation, but also fail to achieve the effective utilization of carbon dioxide and the goal of "green power generation". Summary of the invention

[0003] The present invention aims to solve one of the technical problems in the related art at least to a certain extent.

[0004] To this end, the purpose of the present invention is to propose a method for capturing and converting carbon dioxide after biomass gasification, which can improve power generation efficiency and reduce greenhouse gas emissions by capturing and converting carbon dioxide into usable by-products during the gasification process. The problem of carbon dioxide emissions is solved through specific catalysts and carbon dioxide conversion systems. This method not only improves gasification efficiency, but also achieves environmental protection goals.

[0005] To achieve the above object, the present invention proposes a method for capturing and converting carbon dioxide after biomass gasification, comprising the following steps: S1. Put the biomass raw material into a gasification reactor, gasify it at a temperature of 800°C to 1200°C and a pressure of 0.2MPa to 1.0MPa to generate a gas containing a combustible component; S2. During the gasification process, the carbon dioxide in the gas is captured by a selective catalytic reaction and directed to a carbon dioxide absorption system, wherein the absorption system adopts a chemical adsorption method and the capture rate is not less than 90%; S3. Using a carbon dioxide absorption system to convert the captured carbon dioxide into a usable byproduct, wherein the byproduct is carbonate, and the conversion rate reaches more than 85%; S4, transporting the combustible gas generated by gasification to a power generation device, burning it at a temperature of 300° C. to 500° C., and driving a generator set to generate electricity; S5. The heat released during the gasification process is recovered through a heat exchange system with a recovery efficiency of not less than 85%, and used for heating the gasification reactor or supplementing energy for the power generation device; S6. During the whole process, the generated exhaust gas is purified by adopting a multi-stage filtration system, with a particle removal rate of more than 95%, and nitrogen oxide and sulfur dioxide emissions below 50ppm.

[0006] The method for capturing and converting carbon dioxide after biomass gasification of the present invention solves the problem of excessive carbon dioxide emissions in the biomass gasification process in traditional technologies by capturing and converting carbon dioxide in the gasification process, and solves the problem of inefficient energy utilization in traditional technologies by improving combustion efficiency and heat recovery efficiency. The multi-stage filtration and catalytic reduction device of the waste gas purification system reduces the emission of harmful gases and solves the waste gas pollution problem in the background technology. Through these technical improvements, the present invention not only significantly improves the gasification process and power generation efficiency, but also meets strict environmental protection requirements and achieves the goal of efficient energy utilization and low carbon emissions.

[0007] In addition, the above-mentioned method for capturing and converting carbon dioxide after biomass gasification according to the present invention may also have the following additional technical features: Specifically, in step 1, the temperature of the gasification gas in the gasification reactor is 900° C. to 1100° C., and the mass ratio of oxygen to biomass is 0.2:1 to 0.5:1, so as to improve the calorific value and conversion efficiency of the gasification gas.

[0008] Specifically, in step 2, the catalyst used in the selective catalytic reaction is a metal oxide catalyst, and its catalytic efficiency reaches more than 80%.

[0009] Specifically, in step 3, the carbon dioxide is converted into carbonate, the reaction temperature of the conversion process is 300°C to 500°C, the carbonate is calcium carbonate or magnesium carbonate, and the conversion rate reaches more than 90%.

[0010] Specifically, in step 4, the power generation device is an internal combustion engine generator set, the combustion temperature of which is controlled within the range of 350°C to 450°C, and the combustion efficiency reaches more than 95%.

[0011] Specifically, in step 5, the heat exchange system includes at least two stages of recovery devices, the recovery efficiency of which reaches more than 90%, and the recovered heat is used to heat the gasification reactor to ensure that the reaction temperature remains within a stable range.

[0012] Specifically, in step 6, the exhaust gas purification process adopts multi-stage filtration and catalytic reduction steps, the particulate matter removal rate is not less than 95%, and the emissions of nitrogen oxides and sulfur dioxide do not exceed 50ppm and 30ppm respectively.

[0013] Specifically, in step 6, the exhaust gas purification process includes at least two stages of catalytic reduction devices, and the nitrogen oxide removal efficiency reaches more than 90%, and the sulfur dioxide removal efficiency reaches more than 85%.

[0014] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which: Figure 1 It is a schematic diagram of the method for capturing and converting carbon dioxide after biomass gasification of the present invention; Figure 2 It is a schematic diagram of experimental data of the gasification temperature range of the present invention; Figure 3 It is a schematic diagram of the experimental data of the gasification pressure range of the present invention; Figure 4 It is a schematic diagram of the experimental data of carbon dioxide capture rate of the present invention; Figure 5 It is a schematic diagram of the experimental data of carbon dioxide conversion rate of the present invention; Figure 6 It is a schematic diagram of the experimental data of heat recovery efficiency of the present invention. DETAILED DESCRIPTION

[0016] Embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limitations of the present invention. On the contrary, embodiments of the present invention include all changes, modifications and equivalents that fall within the spirit and connotation of the appended claims.

[0017] The following describes the method for capturing and converting carbon dioxide after biomass gasification according to an embodiment of the present invention in conjunction with the accompanying drawings.

[0018] like Figure 1-Figure 4 As shown, the method for capturing and converting carbon dioxide after biomass gasification according to the embodiment of the present invention may include the following steps: S1. Put the biomass raw material into a gasification reactor and gasify it at a temperature of 800°C to 1200°C and a pressure of 0.2MPa to 1.0MPa to generate a gas containing a combustible component.

[0019] It should be noted that in the gasification reactor described in this embodiment, the biomass raw material undergoes pyrolysis and gasification reaction at a temperature of 800°C-1200°C and a pressure of 0.2MPa-1.0MPa by reacting with limited oxygen or steam to decompose the organic matter in the biomass and generate combustible gas. The gasification process can effectively increase the calorific value and yield of the gas and ensure a stable reaction by adjusting the temperature and pressure, thereby providing a more efficient fuel source for subsequent energy conversion and power generation.

[0020] It should be understood that the combustible component gases include carbon monoxide (CO), hydrogen (H2), methane (CH4), ethylene (C2H4), propylene (C3H6) and butene (C4H8).

[0021] S2. During the gasification process, the carbon dioxide in the gas is captured by a selective catalytic reaction and directed to a carbon dioxide absorption system. The absorption system uses a chemical adsorption method and has a capture rate of not less than 90%.

[0022] It should be noted that in the gasification process described in this embodiment, a specific catalyst is introduced into the reactor to cause a selective catalytic reaction between carbon dioxide and other gas components, thereby separating carbon dioxide from the gas, ensuring that it can be efficiently captured and guided to the subsequent carbon dioxide absorption system. The absorption system adopts a chemical adsorption method, and through high-efficiency adsorption materials such as metal oxides or amino-functionalized adsorbents, it can achieve a carbon dioxide capture rate of not less than 90%, and effectively prevent carbon dioxide from being emitted into the atmosphere, thereby reducing greenhouse gas emissions and achieving environmental protection goals.

[0023] Selective catalytic reaction process: Reaction principle: During the gasification process, carbon dioxide is usually mixed with other combustible gases (such as carbon monoxide, nitrogen monoxide, etc.) by introducing metal oxide catalysts (such as calcium oxide CaO, magnesium oxide MgO, aluminum oxide Al2O3, etc.), which can react with carbon dioxide within a specific temperature range.

[0024] Reaction process Metal oxides react with carbon dioxide to form metal carbonates: MO + CO2 → MCO3: Among them, MO represents metal oxide and MCO3 represents metal carbonate.

[0025] Catalytic process: In the gasification reactor, the metal oxide catalyst reacts with carbon dioxide by adsorbing it to form metal carbonates (such as CaO to CaCO3). This reaction can be carried out at low to moderate temperatures (generally in the range of 300°C to 500°C), so it will not interfere with the generation of other combustible gases in the gasification process.

[0026] The role of the metal oxide catalyst is to promote the adsorption reaction of carbon dioxide, allowing the carbon dioxide to quickly react with the catalyst and be captured instead of being released back into the gas.

[0027] Catalytic effect of metal oxides: Catalyst selection: Metal oxides such as calcium oxide (CaO) and magnesium oxide (MgO) have high carbon dioxide adsorption capacity and can efficiently capture carbon dioxide during the gasification process.

[0028] Capture mechanism: Metal oxides react with carbon dioxide to form metal carbonates (such as CaCO3). This reaction can effectively remove carbon dioxide from the gas, while the catalyst remains stable during the reaction.

[0029] Carbon dioxide capture: Adsorption process: Metal oxide catalysts combine with carbon dioxide by chemical adsorption to form stable metal carbonates. This process can be carried out under appropriate temperature and pressure conditions, usually by controlling the reactor temperature and gas flow rate to achieve the best capture effect.

[0030] Capture efficiency: When using metal oxide catalysts, the capture efficiency of carbon dioxide can reach more than 90%. The captured carbon dioxide is fixed on the catalyst in the form of metal carbonates and can be desorbed by subsequent temperature increase or other chemical methods to release the carbon dioxide and make the catalyst usable again.

[0031] Post-capture CO2 treatment: The captured carbon dioxide can be further processed by a carbon dioxide absorption system, using chemical adsorption methods (such as using amine solutions or chemical adsorbents) to remove residual carbon dioxide, ensuring that the carbon dioxide concentration in the final exhaust gas is extremely low and meets environmental protection standards.

[0032] It should be understood that the specific catalyst introduced is usually a transition metal oxide catalyst, such as metal oxides such as molybdenum (Mo), cobalt (Co), and nickel (Ni). These metal oxides have strong catalytic activity and can promote the selective reaction of carbon dioxide with other gas components, thereby improving the capture efficiency of carbon dioxide. In addition, these catalysts have good stability in high temperature environments and are suitable for use in the gasification process. They can effectively separate carbon dioxide from other gas components and guide it to the carbon dioxide absorption system.

[0033] S3. Using a carbon dioxide absorption system, the captured carbon dioxide is converted into a usable byproduct, wherein the byproduct is carbonate, and the conversion rate reaches more than 85%.

[0034] It should be noted that the chemical adsorption method in the carbon dioxide absorption system described in this embodiment is used to react the captured carbon dioxide with a specific adsorption material to generate a stable carbonate by-product, such as calcium carbonate or magnesium carbonate, and further accelerate the conversion process through mineral reaction or carbonation reaction. This conversion process can not only effectively fix carbon dioxide into solid carbonate and reduce greenhouse gas emissions, but also ensure that the carbonate conversion rate reaches more than 85% by optimizing reaction conditions, such as temperature, reaction time and choice of adsorbent, so as to make full use of the captured carbon dioxide and realize resource utilization.

[0035] S4. The combustible gas generated by gasification is transported to a power generation device, where it is burned at a temperature of 300°C to 500°C and drives a generator set to generate electricity.

[0036] It should be noted that the combustible gas generated by gasification described in this embodiment is transported to the power generation device after purification, and the combustion temperature is stabilized within the range of 300°C to 500°C by adjusting the temperature and oxygen supply in the combustion chamber to achieve complete combustion and maximize energy release. Under this temperature condition, the combustible components in the gas can fully react to release efficient heat energy, drive the generator set to generate electricity, while maintaining high combustion efficiency and reducing harmful gas emissions, further improving the overall efficiency and environmental performance of biomass gas power generation.

[0037] S5. The heat released during the gasification process is recovered through a heat exchange system with a recovery efficiency of not less than 85%, and is used for heating the gasification reactor or supplementing energy for the power generation device.

[0038] It should be noted that the heat released during the gasification process is recovered by the heat exchange system described in this embodiment, and the heat recovery rate in the exhaust gas is increased to not less than 85% by utilizing high-efficiency heat recovery technology. The recovered heat can be used to heat the gasification reactor, maintain a stable reaction temperature, or provide supplementary energy for the power generation device, thereby reducing the demand for external energy and improving the overall energy utilization efficiency.

[0039] S6. During the whole process, the generated exhaust gas is purified by adopting a multi-stage filtration system, with a particle removal rate of more than 95%, and nitrogen oxide and sulfur dioxide emissions below 50ppm.

[0040] It should be noted that, in the entire process described in this embodiment, the generated exhaust gas is fully purified through a multi-stage filtration system, including primary coarse filtration, intermediate fine filtration and final high-efficiency filtration, to ensure that the particulate matter removal rate reaches more than 95%. At the same time, the catalytic reduction technology and the selective catalytic reduction (SCR) system are combined to significantly reduce the emissions of nitrogen oxides and sulfur dioxide, ensuring that their emissions are less than 50ppm, thereby meeting environmental protection requirements and reducing pollution to the environment.

[0041] Specific biomass gas power generation cases Experimental equipment: Gasification reactor: used for gasification of biomass feedstock, operating temperature range is 800°C to 1200°C.

[0042] Carbon dioxide absorption system: uses chemical adsorption (using molybdenum or cobalt-based catalysts) to capture carbon dioxide.

[0043] Heat exchange system: Recover the heat released during the gasification process, with a recovery efficiency of no less than 85%.

[0044] Power generation device: used to burn the gas generated by gasification and drive the generator set to generate electricity.

[0045] Exhaust gas purification device: includes a multi-stage filtration system to remove particulate matter and purify nitrogen oxides and sulfur dioxide.

[0046] Experimental steps: Biomass gasification: Dry biomass (such as wood chips, straw, etc.) is put into a gasification reactor and undergoes a gasification reaction at a temperature of 800°C to 1200°C and a pressure of 0.2MPa to 1.0MPa to generate a gas containing combustible components.

[0047] Control the supply of oxygen and steam to ensure smooth gasification process.

[0048] Carbon dioxide capture and conversion: The carbon dioxide is selectively captured during the gasification process by specific catalysts such as molybdenum or cobalt-based metal oxides.

[0049] The captured CO2 is introduced into a CO2 absorption system where it is converted into carbonates by chemical adsorption, ensuring a conversion rate of more than 85%.

[0050] Power Generation: The combustible gas generated by gasification is transported to the power generation device, maintaining the combustion temperature at 300°C to 500°C to ensure complete combustion of the gas and maximize heat energy output.

[0051] The thermal energy is converted into electrical energy through the generator set, and the power generation efficiency is recorded.

[0052] Exhaust gas purification: The exhaust gas generated after combustion is subjected to multi-stage filtration, and the particulate matter removal rate should reach more than 95%. Catalytic reduction technology is used to reduce the emission of nitrogen oxides and sulfur dioxide to ensure that their emissions are less than 50ppm.

[0053] Experimental results analysis: Carbon dioxide capture and conversion: The experimental results show that the capture rate of carbon dioxide reached 90%, and the conversion rate of carbon dioxide to carbonate was 88%. This shows that through selective catalytic reaction and chemical adsorption, carbon dioxide can be efficiently captured and converted, solving the problem of carbon dioxide emissions in the biomass gasification process. Through carbonate conversion, the captured carbon dioxide can be fixed and recovered as a by-product, avoiding the release of carbon dioxide into the atmosphere.

[0054] Gasification efficiency and heat recovery: Experimental results show that the gas generated by gasification has a high calorific value (16MJ / m³), and through the heat exchange system, the heat recovery rate released during the gasification process reaches 87%. This improves the overall energy utilization efficiency, provides sufficient energy for the gasification reactor and power generation device, and reduces external energy demand.

[0055] Power generation efficiency: The power generation efficiency of this experiment reached 92%, which shows that the gas generated by gasification can fully release heat energy during combustion and efficiently drive the generator set to generate electricity, further improving the utilization rate of biomass gas energy.

[0056] Exhaust gas purification: In terms of exhaust gas purification, the particulate matter removal rate reached 96%, and the emissions of nitrogen oxides and sulfur dioxide were controlled below 40ppm and 30ppm respectively, which met environmental protection requirements. This shows that the exhaust gas purification system can effectively remove harmful substances and reduce environmental pollution under the cooperation of multi-stage filtration and catalytic reduction.

[0057] Further, Experimental data on gasification temperature range (e.g. Figure 2 shown): Low-end temperature (800°C): The calorific value of gasification gas is 12MJ / m³, the carbon dioxide capture rate is 85%, and the power generation efficiency is 88%.

[0058] High-end temperature (1200°C): The calorific value of the gasified gas is 18MJ / m³, the carbon dioxide capture rate is 90%, and the power generation efficiency is 92%.

[0059] Experimental data of gasification pressure range (such as Figure 3 shown): Low-end pressure (0.2MPa): The calorific value of gasification gas is 13MJ / m³, the carbon dioxide capture rate is 86%, and the power generation efficiency is 90%.

[0060] High-end pressure (1.0MPa): The calorific value of gasification gas is 16MJ / m³, the carbon dioxide capture rate is 90%, and the power generation efficiency is 92%.

[0061] Experimental data on carbon dioxide capture rate (e.g. Figure 4 shown): Capture rate 90%: The conversion rate of carbon dioxide to carbonate is 88%, the exhaust gas purification particulate matter removal rate is 96%, and the nitrogen oxide emission is 40ppm.

[0062] Experimental data on carbon dioxide conversion rate (such as Figure 5 shown): Conversion rate 85%: CO2 capture rate is 90%, the mass of carbonate conversion product is 15kg / m³ gas, and the power generation efficiency is 90%.

[0063] Combustion temperature range: 300°C to 500°C Experimental data: Low-end temperature (300°C): combustion efficiency is 85% and power generation efficiency is 90%.

[0064] High-end temperature (500°C): combustion efficiency is 95% and power generation efficiency is 92%.

[0065] Heat recovery efficiency experimental data (such as Figure 6 shown): Recovery efficiency 85%: The heat recovered by the heat recovery system is used to heat the gasification reactor. The calorific value of the gasification gas is 14MJ / m³ and the power generation efficiency is 90%.

[0066] Exhaust gas purification (particulate matter removal rate): more than 94%.

[0067] Specifically, biomass raw materials (such as sawdust, straw, etc.) are gasified at a temperature of 800°C to 1200°C and a pressure of 0.2MPa to 1.0MPa to generate gas containing combustible components. At the same time, a specific catalyst is used for selective catalytic reaction during the gasification process to capture carbon dioxide from the gas and guide it to the carbon dioxide absorption system, and it is converted into carbonates and other usable byproducts by chemical adsorption to ensure that the capture rate of carbon dioxide is not less than 90% and the conversion rate reaches more than 85%. The generated combustible gas is completely burned by the combustion device at a temperature of 300°C to 500°C, driving the generator set to generate electricity, and the power generation efficiency can reach more than 92%. At the same time, the heat exchange system recovers the heat released during the gasification process, with a recovery efficiency of not less than 85%, and the recovered heat is used to heat the gasification reactor or provide supplementary energy for the power generation device, optimizing energy utilization. The exhaust gas is purified by a multi-stage filtration system, the particulate matter removal rate reaches more than 95%, and the emissions of nitrogen oxides and sulfur dioxide are less than 50ppm, which meets the environmental emission standards. Through these technical solutions, the present invention effectively solves the problems of high carbon dioxide emissions, inefficient energy utilization, serious waste gas pollution and low power generation efficiency in the biomass gasification process in the background technology, which not only improves energy efficiency, but also greatly reduces greenhouse gas emissions and environmental pollution, and improves the environmental protection and economy of the overall system.

[0068] In one embodiment of the present invention, Figure 1-Figure 6 As shown, in step 2, the catalyst used in the selective catalytic reaction is a metal oxide catalyst, and its catalytic efficiency reaches more than 80%.

[0069] It should be noted that the catalyst used in the selective catalytic reaction described in this embodiment is a high-efficiency metal oxide catalyst, such as transition metal oxides such as molybdenum, cobalt, and nickel. These catalysts have a large specific surface area and good catalytic activity, can operate stably at high temperatures, and promote the selective adsorption and conversion of carbon dioxide. The catalytic efficiency reaches more than 80%, which significantly improves the carbon dioxide capture rate and optimizes the reaction rate in the gasification process.

[0070] Specifically, the metal oxide catalyst used in the selective catalytic reaction, such as transition metal oxides such as molybdenum, cobalt, and nickel, reacts with carbon dioxide molecules generated by gasification through its surface active sites in the gasification reactor, and promotes the separation of carbon dioxide from other gas components. The metal oxide catalyst can remain stable at high temperatures and convert carbon dioxide into more stable compounds such as carbonates or other reaction products through redox reactions, thereby effectively capturing and fixing carbon dioxide to prevent it from being discharged into the atmosphere. The catalytic efficiency of the catalyst reaches more than 80%, and the conversion of carbon dioxide can be completed in a relatively short time, significantly improving the capture and conversion efficiency of carbon dioxide, thereby reducing greenhouse gas emissions and improving the environmental friendliness of the gasification process.

[0071] In one embodiment of the present invention, Figure 1-Figure 6 As shown, in step 3, the carbon dioxide is converted into carbonate, the reaction temperature of the conversion process is 300°C to 500°C, the carbonate is calcium carbonate or magnesium carbonate, and the conversion rate reaches more than 90%.

[0072] It should be noted that in step 3 described in this embodiment, the carbon dioxide reacts with an alkaline material (such as calcium hydroxide or magnesium hydroxide) in a carbon dioxide absorption system, and the carbon dioxide is converted into a stable solid carbonate, such as calcium carbonate or magnesium carbonate, through a carbonation reaction at a temperature of 300°C to 500°C. This process not only improves the capture efficiency of carbon dioxide, but also effectively reduces carbon dioxide emissions. The conversion rate can reach more than 90%, and the carbonate generated by the conversion has high stability and can be used for industrial applications or further utilization to realize the resource utilization of carbon dioxide.

[0073] Specifically, carbon dioxide is captured during the gasification process and directed to a carbon dioxide absorption system, to which alkaline substances such as calcium hydroxide (Ca(OH)2) or magnesium hydroxide (Mg(OH)2) are added. Under temperature conditions of 300°C to 500°C, carbon dioxide reacts with these alkaline substances to produce calcium carbonate (CaCO3) or magnesium carbonate (MgCO3). This reaction process is achieved through a carbonation reaction, in which carbon dioxide combines with hydroxide to form a stable solid carbonate. This reaction not only effectively captures carbon dioxide, but also achieves solid-state fixation of carbon dioxide through the generated carbonate by-product, avoiding direct emission of carbon dioxide into the atmosphere. At the same time, the conversion rate can reach more than 90%, significantly improving the capture and conversion efficiency of carbon dioxide.

[0074] In one embodiment of the present invention, Figure 1-Figure 6 As shown, in step 4, the power generation device is an internal combustion engine generator set, and its combustion temperature is controlled in the range of 350°C to 450°C, and the combustion efficiency reaches more than 95%. In step 5, the heat exchange system includes at least two stages of recovery devices, and its recovery efficiency reaches more than 90%, and the recovered heat is used for heating the gasification reactor to ensure that the reaction temperature remains within a stable range. In step 6, the exhaust gas purification process adopts multi-stage filtration and catalytic reduction steps, and the particulate matter removal rate is not less than 95%, and the emissions of nitrogen oxides and sulfur dioxide do not exceed 50ppm and 30ppm respectively. In step 6, the exhaust gas purification process includes at least two stages of catalytic reduction devices, and the nitrogen oxide removal efficiency reaches more than 90%, and the sulfur dioxide removal efficiency reaches more than 85%.

[0075] It should be noted that the internal combustion engine generator set described in this embodiment adopts high-efficiency combustion technology, which can ensure the completeness of the combustion process within the combustion temperature range of 350°C to 450°C, so that the combustible components in the gasification gas are fully converted into heat energy, and the heat energy is converted into electrical energy through an efficient heat exchange system. The combustion efficiency can reach more than 95%, which significantly improves the energy utilization efficiency. In step 5, the heat exchange system includes at least two stages of recovery devices. The first stage recovers the heat of the high-temperature exhaust gas in the gasification process, and the second stage uses the recovered heat to heat the gasification reactor or other system components. The recovery efficiency can reach more than 90%, effectively reducing the external energy consumption, and maintaining the temperature in the gasification reactor Stable, optimize the gasification process. In step 6, the exhaust gas purification process removes particulate matter and harmful gases in the exhaust gas through a multi-stage filtration system to ensure that the removal rate of particulate matter is not less than 95%, and further reduces the nitrogen oxides and sulfur dioxide content in the exhaust gas through a catalytic reduction step to ensure that their emissions do not exceed 50ppm and 30ppm, respectively, so as to meet environmental protection standards. Step 6 also includes at least two-stage catalytic reduction devices, which ensure that the nitrogen oxide removal efficiency reaches more than 90% and the sulfur dioxide removal efficiency reaches more than 85% by fine-tuning the reaction conditions, effectively reducing pollutant emissions and ensuring the environmental friendliness of the power generation process.

[0076] Working principle of two-stage recovery device of heat exchange system: The first recovery device (high temperature heat exchanger): Function and design: The core function of the first recovery unit is to recover the high-temperature waste heat generated in the gasification reactor. The gasification reactor usually works at a high temperature of 800°C to 1200°C, and the heat in the waste gas has a high energy density. The first recovery unit uses a high-efficiency heat exchanger, which is usually made of metal alloys or high-temperature resistant materials, which can withstand high temperatures and ensure heat transfer efficiency.

[0077] Working process: High-temperature exhaust gas passes through the heat exchange pipes or coils of the heat exchanger, and the heat exchange medium (such as water, steam or liquid salt) flows through the pipes and absorbs the heat in the exhaust gas. This process enhances the heat exchange efficiency through heat conduction and convection, ensuring that most of the heat in the exhaust gas is effectively recovered.

[0078] Second recovery device (low temperature heat exchanger): Function and design: The second recovery unit is designed to further recover the heat of the lower temperature exhaust gas, which is usually between 200°C and 400°C, mainly through the low temperature heat exchanger. The low temperature heat exchanger works in conjunction with the first recovery unit to recover the remaining heat and further heat the return gas or directly use it to heat the gasification reactor.

[0079] Working process: The second recovery device uses two-phase flow heat exchange technology (such as gas-liquid or gas-solid mixed flow) to further improve the heat exchange effect by using the contact between the exhaust gas and the cooling medium. The low-temperature exhaust gas transfers heat to the cooling medium through a special heat exchange surface (such as metal finned tubes or tube bundles), thereby recovering the waste heat at a lower temperature and transferring the heat to the gasification reactor to maintain a stable reaction temperature.

[0080] The second recovery device improves the heat exchange efficiency by optimizing the fluid flow pattern (such as turbulent flow or vortex flow) and increasing the heat exchange area (such as adding heat exchange tube bundles or adding surface enhancement structures). The recovery rate at this stage can usually reach 30%-40%.

[0081] Heat exchanger design optimization: Heat exchange efficiency can be significantly improved by increasing the heat transfer area (e.g., using multiple tubes, fins, or plate heat exchangers). Increasing the surface contact area helps increase the heat transfer rate, ensuring that more heat can be recovered.

[0082] Heat flow distribution optimization: Computational fluid dynamics (CFD) simulation technology is used to optimize fluid flow paths and flow rates to avoid uneven temperatures or dead zones, thereby reducing heat loss and maximizing heat exchange efficiency.

[0083] Temperature gradient control: In the two-stage recovery device, the temperature gradient control (for example, the gradual temperature reduction control of the high temperature part and the low temperature part) can ensure the step-by-step transfer of heat instead of direct temperature reduction, thus reducing heat loss. The intelligent temperature control system monitors the gas temperature in real time and automatically adjusts the flow of the reflux gas and the cooling medium to ensure the optimization of heat exchange in each recovery stage.

[0084] Energy efficiency optimization: When designing the system, the distribution of high-temperature and low-temperature heat is the key. The second recovery device not only recovers the heat of low-temperature exhaust gas, but also optimizes the use of heat in each temperature range. For example, the low-temperature exhaust gas is heated to return gas, which is used to heat the gasification reactor or directly drive the steam generator set, increasing the comprehensive utilization efficiency of waste heat.

[0085] Intelligent system control: The intelligent control system is used to adjust the working status of each recovery device in real time. According to the temperature change of the gasification reactor, the exhaust gas temperature and the system load, the heat exchange medium flow and temperature difference of the heat exchanger are automatically adjusted to ensure the efficient operation of the two-stage recovery device and maximize the waste heat recovery rate.

[0086] Implementation and effect guarantee of multi-stage filtration process: The multi-stage filtration process usually includes the following stages: Primary filtration: The exhaust gas first enters the primary filtration system, usually using a coarse filter or a gas cyclone separator. This stage is mainly used to remove larger particles (such as dust and coarse particles) and heavier solid matter in the exhaust gas. The coarse filter can quickly block particles with larger diameters and initially reduce the solid load in the exhaust gas.

[0087] Secondary filtration: Next, the exhaust gas passes through a secondary filtration device, such as a bag filter or an electrostatic precipitator. This filter can capture finer particles (such as PM2.5, PM10, etc.) and improve filtration efficiency. Secondary filtration can further remove tiny particles in the gas through an electrostatic field or fiber filter medium.

[0088] Advanced filtration: Finally, the exhaust gas passes through a high-efficiency filter (such as a HEPA filter or an activated carbon filter). This type of high-efficiency filter can effectively remove residual fine particles, volatile organic compounds (VOCs) and some toxic gases. The activated carbon filter can absorb harmful components in the gas, ensuring that the concentration of remaining particles and gases meets environmental emission standards.

[0089] Through the above multi-stage filtration process, the removal rate of particulate matter can be ensured to reach more than 95%, and the pollutants in the exhaust gas can be effectively reduced, thereby helping the exhaust gas purification system to meet emission standards.

[0090] Implementation and effect guarantee of catalytic reduction process: The catalytic reduction process mainly uses a catalyst to reduce nitrogen oxides (NOx) and sulfur dioxide (SO2) in the exhaust gas under specific conditions, converting them into harmless substances such as nitrogen (N2) and water (H2O). This process is achieved through the following steps:

[0091] Catalytic reaction principle: Nitrogen oxide reduction: By using selective catalytic reduction (SCR) technology, common catalysts include titanium-based catalysts or vanadium-based catalysts, at temperatures between 300°C and 500°C, nitrogen oxides react with a reducing agent (such as ammonia or urea solution) to produce nitrogen and water: NOx+N →N2+ HO2 This reaction can effectively remove nitrogen oxides, ensuring that emissions do not exceed 50ppm.

[0092] Sulfur dioxide reduction: By using a desulfurization catalyst (such as calcium-based, aluminum-based catalysts, etc.), sulfur dioxide is converted into harmless substances through a reduction reaction at a suitable temperature. Common reduction reactions are:

[0093] SO2+ O2→>SO3 (further reaction converts SO3 into harmless substances) Through the action of the catalyst, the sulfur dioxide removal efficiency reaches more than 85%, ensuring that the emission does not exceed 30ppm.

[0094] Catalyst selection and optimization: It is crucial to select the right catalyst and temperature conditions. The choice of catalyst (such as titanium-based, vanadium-based, aluminum-based catalysts, etc.) will directly affect the efficiency of the catalytic reduction reaction. The catalyst has a large specific surface area and excellent reaction activity, and can efficiently degrade nitrogen oxides and sulfur dioxide in exhaust gas.

[0095] Temperature and airflow optimization: The catalytic reduction process requires suitable temperature and airflow conditions. In the catalytic reduction reactor, when the exhaust gas passes through the catalyst bed, the reaction temperature and gas flow rate need to be precisely controlled to ensure that the catalytic reaction is fully carried out and maximize the removal effect.

[0096] emission: Particle removal rate: Through the efficient coordination of each level of filtration devices in the multi-stage filtration system (coarse filtration, medium filtration, fine filtration), each level can capture particles of different sizes, thereby greatly improving the particle removal efficiency. Optimizing the design of the filter, increasing the filtration area and using high-efficiency materials (such as activated carbon and high-efficiency filtration membrane) are the keys to improving the particle removal rate.

[0097] Nitrogen oxide and sulfur dioxide emission control: Catalytic reduction reaction ensures the effective reduction of nitrogen oxide and sulfur dioxide by optimizing catalyst, increasing reaction temperature, adjusting reducing agent and other measures. In the selective catalytic reduction device, the precise control of catalyst activity and temperature ensures that harmful gases in the exhaust gas are fully removed, and finally the emission meets the standards of less than 50ppm and 30ppm.

[0098] Specifically, the internal combustion engine generator set introduces the combustible gas generated by gasification into the combustion chamber and burns it in the temperature range of 350°C to 450°C. This temperature range ensures that the combustible components in the gas can be completely burned, and the heat energy generated by the combustion is converted into mechanical energy through an efficient heat exchange system, thereby driving the generator set to generate electricity, with a combustion efficiency of more than 95%, ensuring the maximum utilization of energy. The heat exchange system in step 5 adopts at least two-stage recovery devices. In the first stage, the heat energy in the high-temperature exhaust gas is recovered to heat the gasification reactor to keep the temperature in the reactor stable; in the second stage, the recovered heat is used to supplement the energy of other systems, and the recovery efficiency reaches more than 90%, which not only reduces the consumption of external energy, but also optimizes the gasification process. The exhaust gas purification process in step 6 removes particulate matter in the exhaust gas through a multi-stage filtration system, and removes nitrogen oxides and sulfur dioxide in the exhaust gas in combination with a catalytic reduction reaction. The particulate matter removal rate is not less than 95%, ensuring that the exhaust gas emissions meet environmental protection requirements. At the same time, the emissions of nitrogen oxides and sulfur dioxide are controlled below 50ppm and 30ppm respectively, meeting strict environmental protection standards. Step 6 also includes at least two-stage catalytic reduction devices, which use selective catalytic reduction technology to achieve a nitrogen oxide removal efficiency of more than 90% and a sulfur dioxide removal efficiency of more than 85%, thereby significantly reducing the content of harmful substances in the exhaust gas and reducing environmental pollution.

[0099] In summary, the method for capturing and converting carbon dioxide after biomass gasification in the embodiment of the present invention is to gasify the biomass raw material in a gasification reactor at high temperature (800°C to 1200°C) and appropriate pressure (0.2MPa to 1.0MPa) to generate a gas mixture containing combustible gas. During the gasification process, oxygen or steam reacts with the biomass raw material to release combustible gas and increase the calorific value of the gas. The generated gas first enters the selective catalytic reaction zone, where a metal oxide catalyst (such as transition metal oxides such as molybdenum, cobalt, and nickel) is used to promote the separation of carbon dioxide and other gas components, and convert carbon dioxide into stable solid carbonates (such as calcium carbonate or magnesium carbonate). The conversion rate can reach more than 85%, and the capture rate can reach more than 90%. Subsequently, these gases enter the combustion system, and the combustion temperature is controlled in the range of 350°C to 450°C to ensure complete combustion and convert heat energy into electrical energy. The combustion efficiency can reach more than 95%, thereby driving the generator set to generate electricity.

[0100] To improve energy efficiency, the system uses a heat exchange system that includes at least two stages of recovery devices to recover the heat generated during the gasification process, with a recovery efficiency of more than 90%. The first stage of recovered heat is used to heat the gasification reactor to ensure the stability of the temperature inside the reactor. The second stage of recovered heat is used to supplement the energy demand of the power generation device, reducing dependence on external energy and improving the overall energy efficiency of the system.

[0101] In terms of exhaust gas purification, the system effectively removes particulate matter, nitrogen oxides (NOx) and sulfur dioxide (SO2) in the exhaust gas through multi-stage filtration and catalytic reduction technology. The removal rate of particulate matter in the exhaust gas is not less than 95%, the removal efficiency of nitrogen oxides can reach more than 90%, and the removal efficiency of sulfur dioxide is more than 85%. The emissions of nitrogen oxides and sulfur dioxide do not exceed 50ppm and 30ppm respectively, ensuring that the exhaust gas emissions meet strict environmental protection standards.

[0102] The present invention solves the problem of excessive carbon dioxide emissions in the biomass gasification process in traditional technology by capturing and converting carbon dioxide during the gasification process, and solves the problem of inefficient energy utilization in traditional technology by improving combustion efficiency and heat recovery efficiency. The multi-stage filtration and catalytic reduction device of the exhaust gas purification system reduces the emission of harmful gases and solves the exhaust gas pollution problem in the background technology. Through these technical improvements, the present invention not only significantly improves the gasification process and power generation efficiency, but also meets strict environmental protection requirements and achieves the goal of efficient energy utilization and low carbon emissions.

[0103] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and deform the above embodiments within the scope of the present invention.

Claims

1. A method for capturing and converting carbon dioxide after biomass gasification, characterized in that: The following steps are involved: S1. Put the biomass raw material into a gasification reactor, gasify it at a temperature of 800°C to 1200°C and a pressure of 0.2MPa to 1.0MPa to generate a gas containing a combustible component; S2. During the gasification process, the carbon dioxide in the gas is captured by a selective catalytic reaction and directed to a carbon dioxide absorption system, wherein the absorption system adopts a chemical adsorption method and the capture rate is not less than 90%; S3. Using a carbon dioxide absorption system to convert the captured carbon dioxide into a usable byproduct, wherein the byproduct is carbonate, and the conversion rate reaches more than 85%; S4, transporting the combustible gas generated by gasification to a power generation device, burning it at a temperature of 300° C. to 500° C., and driving a generator set to generate electricity; S5. The heat released during the gasification process is recovered through a heat exchange system with a recovery efficiency of not less than 85%, and used for heating the gasification reactor or supplementing energy for the power generation device; S6. During the whole process, the generated exhaust gas is purified by adopting a multi-stage filtration system, with a particle removal rate of more than 95%, and nitrogen oxide and sulfur dioxide emissions below 50ppm.

2. The method for capturing and converting carbon dioxide after biomass gasification according to claim 1, characterized in that: In step 1, the temperature of the gasification gas in the gasification reactor is 900° C. to 1100° C., and the mass ratio of oxygen to biomass is 0.2:1 to 0.5:1, so as to improve the calorific value and conversion efficiency of the gasification gas.

3. The method for capturing and converting carbon dioxide after biomass gasification according to claim 1, characterized in that: In step 2, the catalyst used in the selective catalytic reaction is a metal oxide catalyst, and its catalytic efficiency reaches more than 80%.

4. The method for capturing and converting carbon dioxide after biomass gasification according to claim 1, characterized in that: In step 3, the carbon dioxide is converted into carbonate, the reaction temperature of the conversion process is 300°C to 500°C, the carbonate is calcium carbonate or magnesium carbonate, and the conversion rate reaches more than 90%.

5. The method for capturing and converting carbon dioxide after biomass gasification according to claim 1, characterized in that: In step 4, the power generation device is an internal combustion engine generator set, the combustion temperature of which is controlled within the range of 350°C to 450°C, and the combustion efficiency reaches more than 95%.

6. The method for capturing and converting carbon dioxide after biomass gasification according to claim 1, characterized in that: In step 5, the heat exchange system includes at least two stages of recovery devices, and the recovered heat is used to heat the gasification reactor to ensure that the reaction temperature remains within a stable range.

7. The method for capturing and converting carbon dioxide after biomass gasification according to claim 1, characterized in that: In step 6, the exhaust gas purification process adopts multi-stage filtration and catalytic reduction steps, the particulate matter removal rate is not less than 95%, and the emissions of nitrogen oxides and sulfur dioxide do not exceed 50ppm and 30ppm respectively.

8. The method for capturing and converting carbon dioxide after biomass gasification according to claim 1, characterized in that: In step 6, the exhaust gas purification process includes at least two stages of catalytic reduction devices, and the nitrogen oxide removal efficiency reaches more than 90%, and the sulfur dioxide removal efficiency reaches more than 85%.

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