Green energy production process for producing hydrogen by combining biogas separation-biogas residue gasification with wind-solar water electrolysis

Abstract

The invention relates to the technical field of green energy, in particular to a green energy production process for producing hydrogen by combining biogas separation-biogas residue gasification with wind-solar water electrolysis. A set of green energy production process for deeply coupling biomass waste recycling and wind-solar power generation absorption is constructed, the set of process comprises two processes, one process can co-produce green methane and green methanol, and the other process only generates green methane. Biogas and biogas residues produced by anaerobic fermentation of biomass or garbage waste are used as basic raw materials, a wind-solar power generation driven water electrolysis hydrogen production technology is fused, and green methane or green methanol is generated by separating the biogas, gasifying the biogas residues and carrying out multi-step chemical reaction, so that a low-carbon energy closed loop is created, and a firm technical support is achieved for a double-carbon target; and the sustainability and the stability of energy supply are obviously improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of green energy technology, and particularly relates to a green energy production process of biogas separation-biogas residue gasification coordinated with wind-solar electricity water electrolysis hydrogen production. BACKGROUND

[0002] Under the background of global energy transformation and response to climate change, the extensive use of traditional fossil energy has brought many serious problems. Fossil fuels such as coal, oil and natural gas not only face the dilemma of decreasing reserves, but also emit a large amount of greenhouse gases, especially carbon dioxide, which has become the main driver of global warming. According to the data of the International Energy Agency (IEA), in the past few decades, the global carbon dioxide emissions caused by fossil energy consumption have continued to rise, causing immeasurable damage to the ecological environment. At the same time, the supply of fossil fuels is affected by geopolitical, uneven resource distribution and other factors, and the price fluctuates frequently and the supply stability is poor, which seriously threatens the energy security of each country. Under this situation, it is urgent to develop clean, sustainable and widely available green energy.

[0003] Biomass and waste as important renewable resources and solid waste treatment objects, their collaborative conversion and utilization are of key significance to carbon cycle and energy regeneration. The organic components account for a high proportion in the biomass and municipal solid waste generated in China every year, and these raw materials can be converted into biogas rich in methane and carbon dioxide through anaerobic fermentation. However, the traditional biogas utilization mode only stays in combustion for heating or simple power generation, and the carbon dioxide in the mixed gas is not utilized as a resource, and impurities can easily cause equipment corrosion and low energy conversion efficiency. It is worth noting that the direct emission of biogas produced by anaerobic fermentation in the landfill will exacerbate the greenhouse effect, and the natural degradation process of biomass will lead to waste of carbon resources.

[0004] In the existing technical field, there are explorations for energy conversion and utilization. Patent CN202411318420 "A regional multi-energy control system and method" effectively utilizes renewable energy such as solar energy, wind energy and bioenergy by deeply coupling a methanation reactor, a supercritical carbon dioxide heat and power cogeneration unit, a water electrolysis hydrogen production system, a biogas tank, a biogas purification device, etc., realizes the output of cold, heat, electricity and gas in multiple energy forms, and achieves the goal of energy saving, emission reduction and cost reduction. However, there is no research on the efficient conversion and utilization of biogas and biogas residue produced by biomass and waste, the full play of the advantages of wind and solar power generation, and the systematic integration of green, sustainable and carbon cycle green energy generation process.

[0005] Therefore, the present application aims to fill this gap and proposes a new green methane and green methanol generation process, which efficiently converts biogenic gas and biogenic residue generated from biomass and waste, couples wind and solar power green electricity, and realizes the utilization of carbon dioxide through a systematic process, thereby constructing a closed-loop system of "renewable energy-green hydrogen-green energy" and providing an innovative solution for global energy transformation and carbon neutralization. SUMMARY

[0006] The present application aims to provide a green energy production process of biogas separation-biogenic residue gasification coupled with wind and solar water electrolysis hydrogen production.

[0007] To achieve the above application purpose, the technical solution adopted by the present application is as follows:

[0008] In a first aspect, the present application provides a green energy production process of biogas separation-biogenic residue gasification coupled with wind and solar water electrolysis hydrogen production, comprising the following steps:

[0009] (1) anaerobic fermentation of biomass or waste to generate biogas and biogenic residue;

[0010] (2) separation of biogas to obtain methane and carbon dioxide;

[0011] (3) water electrolysis to produce hydrogen using wind and solar green electricity;

[0012] (4) using carbon dioxide as a gasification agent to generate synthesis gas from biogenic residue;

[0013] (5) after purifying the synthesis gas, any one of the following processes is selected:

[0014] co-production process: synthesis gas reacts with hydrogen to generate methanol, and separated methane is used as a product;

[0015] single production process: synthesis gas reacts with hydrogen to generate methane;

[0016] (6) recycling of unreacted gas and resource utilization of excess carbon dioxide.

[0017] In some embodiments, the specific steps of the co-production process include: mixing the purified synthesis gas with the hydrogen produced in step (3) at a volume ratio of 1:2, synthesizing methanol under the action of a catalyst, and obtaining green methanol products after rectification and purification; at the same time, the separated methane in step (2) is directly used as a green methane product.

[0018] In some embodiments, the specific steps of the single production process include: mixing the purified synthesis gas with the hydrogen produced in step (3) at a volume ratio of 1:3, performing methanation under the action of a catalyst, and generating green methane products.

[0019] In some embodiments, the methanol synthesis reaction temperature of the co-production process is 200-300℃, and the pressure is 5-10MPa.

[0020] In some embodiments, the methanation reaction temperature of the single production process is 250-400℃, and the pressure is 3-8MPa.

[0021] In some embodiments, in step (2), the biogas is sequentially pretreated and separated, wherein the pretreatment includes water washing, desulfurization and drying, and the separation adopts pressure swing adsorption, membrane separation or absorption desorption technology.

[0022] In some embodiments, in step (4), the carbon dioxide is used as a gasification agent to participate in the gasification reaction of the biogas residue, so as to increase the content of carbon monoxide in the synthesis gas and reduce the emission of carbon dioxide.

[0023] In some embodiments, in step (4), the composition of the synthesis gas is: 40-60% of carbon monoxide, 8-15% of hydrogen, and 20-30% of carbon dioxide.

[0024] In some embodiments, in step (3), the water electrolysis for hydrogen production adopts an alkaline electrolytic tank or a PEM electrolytic tank, and the purity of hydrogen is ≥99.9%.

[0025] In some embodiments, in step (5), the step of purifying the synthesis gas specifically includes dust removal, desulfurization and decarburization treatment, and the removed sulfide is further processed into sulfur or sulfuric acid products.

[0026] In some embodiments, in step (1), the raw material of anaerobic fermentation is biomass or urban organic waste, and the water content is controlled at 30%-60%.

[0027] In some embodiments, in step (6), the excess carbon dioxide is used as a liquefied carbon dioxide product or a supplementary gasification agent to realize the full closed-loop utilization of carbon resources.

[0028] In some embodiments, the wind-solar power generation system includes a wind turbine generator set and a solar photovoltaic panel, and the power fluctuation is smoothed by an intelligent power grid management system, and power is preferentially supplied to the water electrolysis for hydrogen production.

[0029] The green energy production process of the biogas separation-biogas residue gasification coordinated wind-solar water electrolysis for hydrogen production provided in the first aspect of the present application includes two processes, one of which can co-produce green methane and green methanol, and the other of which can only produce green methane, including:

[0030] (1) Biomass carbon closed-loop and high-value utilization:

[0031] Break through the traditional biogas single utilization mode, separate the biogas produced by anaerobic fermentation; purify the methane in the biogas as green methane product; at the same time, separate the carbon dioxide as gasification agent, and gasify the treated biogas residue to synthesize carbon monoxide and hydrogen as the main synthesis gas, and then purify the synthesis gas and green hydrogen produced by wind and light green electricity to synthesize methanol or methane, which is converted into high value-added green energy. A closed loop cycle path of carbon dioxide from "waste gas" to "gasification agent" in the anaerobic fermentation process is constructed, which significantly improves the utilization rate of biomass carbon resources and carbon emission reduction benefit.

[0032] (2) Carbon dioxide synergistic gasification and carbon resource optimization:

[0033] The innovation is to introduce part of the carbon dioxide as a gasification agent into the biogas residue gasification furnace. The carbon dioxide participates in the gasification reaction, significantly increasing the carbon monoxide content in the product gas and greatly reducing the ineffective emission of carbon dioxide. This technology effectively improves the carbon conversion rate in the gasification process and slightly improves the cold coal gas efficiency. The obtained synthesis gas rich in carbon monoxide provides an ideal raw material for the subsequent efficient synthesis of green methane or green methanol with green hydrogen, realizing the resource utilization of carbon dioxide and the synergistic optimization of the gasification process.

[0034] (3) Modular process and flexible product strategy:

[0035] A set of deeply integrated processes is designed for different needs: the cogeneration process realizes the cogeneration of green methane and green methanol through biogas residue gasification (utilizing carbon dioxide gasification for synergistic effect) and methanol synthesis, maximizing resource value; the single production process efficiently produces green methane through biogas residue gasification and methanation reaction. Both processes have core units such as anaerobic fermentation, biogas separation, and green electricity hydrogen production, providing modular and configurable solutions to adapt to different raw materials and markets. BRIEF DESCRIPTION OF DRAWINGS

[0036] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and those skilled in the art can also obtain other drawings according to these drawings without creating any creative labor.

[0037] Figure 1 is the green methane-green methanol cogeneration process analysis diagram provided by the biogas separation-biogas residue gasification synergistic wind and light water electrolysis hydrogen production process provided by the embodiments of the present application.

[0038] Figure 2 is the green methane production process analysis diagram provided by the biogas separation-biogas residue gasification synergistic wind and light water electrolysis hydrogen production process provided by the embodiments of the present application. DETAILED DESCRIPTION

[0039] In order to make the technical problems, technical solutions and beneficial effects to be solved in the present application clearer, the present application will be further described in detail below in conjunction with embodiments. It should be understood that the specific embodiments described herein are only intended to explain the present application and not to limit the present application.

[0040] In the present application, the term "and / or" describes the association relationship of the associated objects, which means that there can be three kinds of relationships, for example, A and / or B can represent the following three cases: A exists alone, A and B exist together, and B exists alone. Wherein A and B can be singular or plural. The character " / " generally represents an "or" relationship between the associated objects before and after it.

[0041] In the present application, "at least one" means one or more, and "multiple" means two or more. "At least one of the following" or the like means any combination of these items, including any combination of single item or multiple items. For example, "at least one of a, b, or c", or "at least one of a, b, and c", can represent a, b, c, a-b (i.e. a and b), a-c, b-c, or a-b-c, wherein a, b, and c can be single or multiple.

[0042] It should be understood that in various embodiments of the present application, the size of the sequence number of the above-mentioned processes does not mean the order of execution, and part or all of the steps can be executed in parallel or in sequence. The execution order of each process should be determined according to its function and inherent logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0043] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a" and "the" used in the embodiments of the present application and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise.

[0044] The weight of the related components mentioned in the specification of the embodiments of the present application can not only refer to the specific content of each component, but also represent the proportional relationship between the weights of each component. Therefore, as long as the content of the related components in the specification of the embodiments of the present application is enlarged or reduced in proportion, it is within the scope disclosed in the specification of the embodiments of the present application. Specifically, the mass mentioned in the specification of the embodiments of the present application can be μg, mg, g, kg and other mass units commonly known in the chemical field.

[0045] The terms "first" and "second" are used for descriptive purposes only, to distinguish objects, such as substances, from one another, and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. For example, without departing from the scope of the embodiments of this application, a first XX may also be referred to as a second XX, and similarly, a second XX may also be referred to as a first XX. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of that feature.

[0046] The first aspect of this application provides a green energy production process for hydrogen production through biogas separation-biogas residue gasification combined with wind, solar and water electrolysis, including the following steps:

[0047] (1) Anaerobic fermentation of biomass or waste to produce biogas and biogas residue;

[0048] (2) Separate biogas to obtain methane and carbon dioxide;

[0049] (3) Hydrogen production by electrolyzing water using wind and solar green electricity;

[0050] (4) Using carbon dioxide as a gasifying agent, biogas residue is gasified to generate syngas;

[0051] (5) After purifying the synthesis gas, select any of the following processes:

[0052] Cogeneration process: Syngas reacts with hydrogen to produce methanol, while the separated methane is used as a product;

[0053] Single-product process: Syngas reacts with hydrogen to produce methane;

[0054] (6) Unreacted gases are recycled and excess carbon dioxide is treated as a resource.

[0055] The green energy production process for biogas separation-biogas residue gasification combined with wind, solar and water electrolysis to produce hydrogen provided in the first aspect of this application has the following beneficial effects compared with the prior art:

[0056] ① Carbon emission reduction and efficiency improvement driven by carbon dioxide gasification agent

[0057] Carbon dioxide, as a gasifying agent, changes the traditional biogas treatment method of direct emission or inefficient utilization of carbon dioxide. By participating in the biomass gasification reaction, it improves carbon conversion efficiency, increases the proportion of carbon monoxide in syngas, provides better raw materials for subsequent synthesis of methane or methanol, and promotes resource utilization.

[0058] ② Multi-energy complementary low-carbon energy supply network

[0059] The process has flexible product adaptability, and can plan to produce methane or methanol according to the needs. Methane can be connected to the pipeline or stored as high-calorie fuel, and methanol can be used as a chemical raw material or liquid fuel, meeting the application needs of different energy scenarios and enhancing the flexibility of energy supply.

[0060] ③Full-component efficient utilization of biomass or waste biogas residue

[0061] The full-component efficient utilization of biogas resources is achieved, carbon dioxide in the biogas is recovered through separation technology and is reused in the gasification link, and methane is purified to avoid resource waste. This process reduces carbon dioxide emissions, builds a conversion chain from biogas to high-value energy products, and balances environmental protection and economic value.

[0062] Further, a green methane-green methanol co-production process of biogas separation-biogas residue gasification coupled with wind-solar water electrolysis hydrogen production, the process includes waste anaerobic fermentation device, biogas separation device, biogas residue gasification device, wind-solar power coupling water electrolysis hydrogen production device, syngas purification device, methanol synthesis and rectification device, product purification device, etc.

[0063] Further, step (1) anaerobically ferments biomass or waste to generate biogas and biogas residue.

[0064] In some embodiments, the raw material for anaerobic fermentation in step (1) is biomass or municipal organic waste, and the water content is controlled at 30-40%. Using biomass or municipal organic waste as the raw material for anaerobic fermentation, these raw materials are widely available and belong to renewable resources, which not only reduces the dependence on fossil energy in the process, but also realizes waste reduction and resource treatment, relieving environmental pressure; controlling the water content of the raw material at 30-60% can optimize the anaerobic fermentation environment, improve the biogas yield and fermentation efficiency, and ensure stable supply of raw materials at the source of the process.

[0065] Further, step (2) separates the biogas to obtain methane and carbon dioxide.

[0066] In some embodiments, in step (2), the biogas is sequentially pretreated and separated, wherein the pretreatment includes water washing, desulfurization and drying, and the separation uses pressure swing adsorption, membrane separation or absorption desorption technology. The biogas pretreatment step can effectively remove impurities (such as sulfides, moisture, etc.) in the biogas, avoiding corrosion or poisoning of the subsequent separation equipment and reaction system, and prolonging the service life of the equipment; the application of various separation technologies provides flexible selection for the process, and appropriate separation methods can be selected according to the actual production scale, cost budget, etc. to ensure that the purity of the separated methane and carbon dioxide meets the standards and provides high-quality raw materials for the subsequent process.

[0067] Further, step (3) uses wind-solar green electricity to electrolyze water to produce hydrogen.

[0068] In some embodiments, the water electrolysis in step (3) is carried out using an alkaline electrolyzer or a PEM electrolyzer, and the hydrogen purity is ≥99.9%. The alkaline electrolyzer or the PEM electrolyzer is selected for water electrolysis to produce hydrogen, and these two types of equipment are mature in technology and stable in operation, and can efficiently produce high-purity hydrogen (≥99.9%). The high-purity hydrogen can be directly used in subsequent synthesis reactions, avoiding the adverse effects of impurities on the reaction catalyst and product quality, ensuring the quality of the final product, and providing a guarantee for the stable operation of the process.

[0069] Further, in step (4), the biogas residue is gasified using carbon dioxide as a gasification agent to produce synthesis gas.

[0070] In some embodiments, in step (4), carbon dioxide is used as a gasification agent to participate in the gasification reaction of the biogas residue, which increases the carbon monoxide content in the synthesis gas and reduces carbon dioxide emissions. Using carbon dioxide as a gasification agent for the biogas residue not only realizes the resource utilization of carbon dioxide and reduces greenhouse gas emissions, but also helps to adjust the component ratio of the synthesis gas and increase the carbon monoxide content, which is a key raw material for synthesizing methanol and methane, thereby improving the utilization value of the synthesis gas and the efficiency of subsequent reactions.

[0071] In some embodiments, in step (4), the synthesis gas composition is: carbon monoxide 40-60%, hydrogen 8-15%, and carbon dioxide 20-30%. Defining the composition range of the synthesis gas provides a reliable basis for setting subsequent process parameters, which is beneficial to ensure production stability.

[0072] Further, after purifying the synthesis gas in step (5), any one of the following processes is selected:

[0073] Co-production process: synthesis gas reacts with hydrogen to produce methanol, and separated methane is used as a product;

[0074] Single production process: synthesis gas reacts with hydrogen to produce methane.

[0075] In some embodiments, the specific steps of the co-production process include: mixing the purified synthesis gas with the hydrogen produced in step (3) at a volume ratio of 1:2, synthesizing methanol under the action of a catalyst, and obtaining green methanol products after rectification and purification; at the same time, the separated methane in step (2) is directly used as a green methane product. In the co-production process, the specific ratio of synthesis gas and hydrogen can efficiently promote the synthesis of methanol, improve the yield and purity of methanol, and the separated methane can be directly used as a product, realizing the coordinated production of multiple high-value energy products.

[0076] In some embodiments, the methanol synthesis reaction temperature of the co-production process is 200-300 DEG C, and the pressure is 5-10 MPa. Under this condition, the catalyst can maintain high activity, the reaction rate is moderate, the selectivity and conversion rate of the target product can be effectively improved, the occurrence of side reactions is reduced, the energy consumption is reduced, the production efficiency and cost control are considered, and the process is more feasible in industrial implementation.

[0077] In some embodiments, the specific steps of the single production process include: mixing the purified synthesis gas with the hydrogen gas prepared in step (3) at a volume ratio of 1:3, and performing a methanation reaction under the action of a catalyst to generate green methane products. The ratio setting of the single production process optimizes the methanation reaction conditions, which is beneficial to improve the generation efficiency and quality of methane, and the specific parameters of the two processes are clear, which is convenient for industrial application and stable production, and improves the practicality and reliability of the process.

[0078] In some embodiments, the methanation reaction temperature of the single production process is 250-400 DEG C, and the pressure is 3-8 MPa.

[0079] In some embodiments, the step of purifying synthesis gas in step (5) specifically includes dust removal, desulfurization and decarburization treatment, and the removed sulfides are further processed into sulfur or sulfuric acid products. The dust removal, desulfurization and decarburization treatment in the synthesis gas purification process can effectively remove solid particles, sulfides and excess carbon dioxide, and the purified synthesis gas can meet the requirements of the subsequent reaction on the purity of the raw material, improve the reaction efficiency and product purity; and the removed sulfides are processed into sulfur or sulfuric acid products, realizing the resource utilization of pollutants, increasing the added value of the process, and reducing environmental pollution.

[0080] Further, the unreacted gas in step (6) is recycled and the excess carbon dioxide is treated as a resource.

[0081] In some embodiments, in step (6), the excess carbon dioxide is used as liquefied carbon dioxide products or as a supplementary gasification agent to realize the full closed-loop utilization of carbon resources. The resource treatment of excess carbon dioxide, whether as liquefied carbon dioxide products or as a supplementary gasification agent, realizes the recycling of carbon elements, builds a full closed-loop system of carbon resources, maximizes the reduction of carbon emissions, and meets the carbon neutralization target; at the same time, the utilization efficiency of carbon resources is improved, and the economic efficiency and environmental benefits of the process are increased.

[0082] In some embodiments, the wind-solar power generation system includes a wind turbine generator and a solar photovoltaic panel, which is managed by a smart grid management system to smooth power fluctuations and prioritize power supply for water electrolysis hydrogen production. The wind-solar power generation system combines wind and solar renewable energy, which can make full use of natural resources and improve the stability and sustainability of energy supply; the smart grid management system can effectively smooth power fluctuations and ensure stable power supply for key processes such as water electrolysis hydrogen production, avoiding the impact of unstable power supply on production efficiency and product quality; prioritizing power supply for water electrolysis hydrogen production improves the utilization efficiency of green electricity and ensures the green properties of hydrogen, further enhancing the environmental value of the entire process.

[0083] Green methane-green methanol co-production process of biogas separation-biogas residue gasification coordinated with wind-solar water electrolysis hydrogen production

[0084] A green methane-green methanol co-production process of biogas separation-biogas residue gasification coordinated with wind-solar water electrolysis hydrogen production, as shown in Figure 1 The process includes a waste anaerobic fermentation device, a biogas separation device, a biogas residue gasification device, a wind-solar power generation coupled water electrolysis hydrogen production device, a syngas purification device, a methanol synthesis and rectification device, and a product purification device.

[0085] Biomass or waste as initial raw material fermentation to produce biogas and biogas residue, biogas is transported to the inlet of the pretreatment device, after water washing, desulfurization, drying and other processes, it is separated into carbon dioxide and methane at the outlet of the pretreatment device, and the purified methane is used as a product. The wind-solar power generation device supplies power to the water electrolysis device, and the desalted water enters the water electrolysis device to undergo an electrochemical reaction to obtain hydrogen and oxygen. Carbon dioxide in biogas is used as a gasification agent, and biogas residue is treated and then enters the gasification device to undergo a gasification reaction to generate syngas containing carbon monoxide, hydrogen and other components. After removing dust, sulfides and other impurities in the purification device, the syngas is mixed with hydrogen obtained by water electrolysis to meet the volume ratio requirement of 1:2 of carbon monoxide and hydrogen, and the mixed gas is compressed and enters the methanol synthesis reactor inlet to react under the conditions of catalyst and specific temperature and pressure to generate methanol. The crude methanol gas enters the methanol rectification device to remove light components (such as unreacted carbon monoxide and hydrogen) and heavy components (such as higher alcohols and water), and finally high-purity green methanol products are obtained from the outlet. Unreacted carbon monoxide and hydrogen are returned to the reactor from the recycle gas outlet for recycling.

[0086] In one specific embodiment, a green methane-green methanol co-production process of biogas separation-biogas residue gasification coordinated with wind-solar water electrolysis hydrogen production, the detailed example route is as follows:

[0087] (1) Anaerobic fermentation and biogas and biogas residue separation

[0088] The biomass or waste is transported to an anaerobic fermentation device, and under the action of microorganisms in an anaerobic environment at a suitable temperature, the organic matter is decomposed and converted to produce biogas and biogas residue. The biogas produced by fermentation is collected and transported to the subsequent biogas separation section; the biogas residue enters the biogas residue treatment process.

[0089] (2) Biogas separation and methane purification

[0090] During the pretreatment of biogas, most of the water-soluble impurities in the biogas, such as part of the hydrogen sulfide and carbon dioxide, are removed by using the absorption of water in the water washing tower. Then, the biogas is further removed of hydrogen sulfide to reduce its content to meet the requirements of the subsequent reaction. Then, the biogas treated by water washing and desulfurization is sent to a drying tower, and molecular sieves or silica gel are used as drying agents to remove water in the biogas to avoid the adverse effects of water on the subsequent reaction. By using the differences in physical or chemical properties between methane and carbon dioxide and other components, the biogas is separated into methane and carbon dioxide by pressure swing adsorption, membrane separation or absorption desorption technology. The separated methane enters the methane purification unit and is again purified by a deep purification process to remove trace impurities (such as sulfides, nitrogen oxides, residual carbon dioxide, etc.), and finally green methane products with standard purity are obtained, which are output from the device outlet.

[0091] (3) Biogas residue treatment and gasification

[0092] The biogas residue first enters the biogas residue treatment device, and by pretreatment processes such as dewatering, crushing and screening, large-particle impurities are removed and the moisture content is adjusted to meet the gasification feed requirements. The treated biogas residue is transported to the biogas residue gasification device, and carbon dioxide from the biogas separation section is used as a gasification agent to occur a gasification reaction in the gasification device, converting the solid organic matter in the biogas residue into synthesis gas containing carbon monoxide, hydrogen and other components.

[0093] (4) Wind-solar power generation coupled with water electrolysis to produce hydrogen

[0094] The wind-solar energy is collected, and the wind turbine generator and the solar photovoltaic panel are used for cooperative power generation or separate power generation, and the output power is integrated by an intelligent power grid management system. During power generation, a storage device is first connected to smooth the intermittent fluctuations of wind-solar power and ensure power stability by using the buffering effect of the storage medium. Then, the integrated power is fed into the water electrolysis device, and an alkaline electrolytic cell or a PEM electrolytic cell is selected according to the process requirements to perform electrolysis. The hydrogen-oxygen mixed gas produced by electrolysis is sent to a gas-liquid separation device. The separated hydrogen enters a purification unit to increase its purity to ≥99.9%, so that it meets the raw gas standard for the subsequent reaction. The purified hydrogen enters a pressure-regulating buffer tank to supply continuous and stable hydrogen source for the downstream methanol / methane synthesis.

[0095] (5) Synthesis gas purification

[0096] The synthesis gas produced by gasification of the biogas residue contains dust, sulfides, carbon dioxide and other impurities, which need to be sent to a synthesis gas purification device. The dust is removed by a dust removal unit, and the sulfides and carbon dioxide are removed by a desulfurization and decarbonization device, to obtain a mixture of carbon monoxide and hydrogen gas (also containing a small amount of carbon dioxide). The purified synthesis gas is mixed with hydrogen gas (after pressure adjustment and buffering) from the water electrolysis hydrogen production link in a certain proportion, as the raw material for methanol synthesis, and is delivered to the inlet of the methanol synthesis reactor.

[0097] (6) Methanol synthesis and rectification

[0098] The mixture of carbon monoxide and hydrogen gas enters the methanol synthesis reactor, where, under the action of a catalyst at a specific temperature and pressure, a methanol synthesis reaction occurs, generating a mixture containing methanol, unreacted raw material gas and water. The mixture is sent to a methanol rectification device, where, through a multi-tower rectification process, light components and heavy components are removed in turn, and finally, high-purity green methanol products are obtained from the outlet of the rectification device. Unreacted carbon monoxide and hydrogen gas can be recycled to the reactor for recycling.

[0099] Green methane production process of biogas separation-biogas residue gasification coordinated with wind-solar water electrolysis hydrogen production

[0100] A green methane production process of biogas separation-biogas residue gasification coordinated with wind-solar water electrolysis hydrogen production, as shown in Figure 2 The process includes waste anaerobic fermentation device, biogas separation device, biogas residue gasification device, wind-solar power coupling water electrolysis hydrogen production device, gasification synthesis gas purification device, methane synthesis device, product purification device, etc.

[0101] Substance or garbage waste is fermented as initial raw material to produce biogas and biogas residue. The biogas is delivered to the inlet of the pretreatment device, treated by water washing, desulfurization, drying and other processes, and separated into carbon dioxide and methane from the outlet of the pretreatment device. The methane is purified and used as a product. The wind-solar power device supplies power to the water electrolysis device, and desalted water enters the water electrolysis device to undergo an electrochemical reaction to obtain hydrogen and oxygen. The carbon dioxide in the biogas is used as a gasification agent, and the biogas residue is treated and enters the gasification device to undergo a gasification reaction to generate synthesis gas containing carbon monoxide, hydrogen and other components. The synthesis gas is purified by a purification device to remove dust, sulfides and other impurities, and mixed with hydrogen produced by water electrolysis to meet the volume ratio requirement of 1:3 of carbon monoxide and hydrogen. The mixture enters the methanation reactor inlet and reacts under the action of a catalyst and specific temperature and pressure to generate methane. The reaction product is a mixture containing methane, water and unreacted carbon monoxide and hydrogen. After removing water and impurities, high-purity green methane products are obtained. Unreacted carbon monoxide and hydrogen are returned to the reactor from the recycle gas outlet for recycling.

[0102] In the above scheme, if the amount of carbon dioxide in the biogas is insufficient for the amount of gasification agent required for gasification of the biogas residue, the removed carbon dioxide in the synthesis gas is purified and then added as a supplement into the gasification device. If the biogas gasification agent does not need to be supplemented, the excess carbon dioxide in the biogas and the removed carbon dioxide in the synthesis gas are subjected to liquefaction treatment, and can be used as a liquid carbon dioxide product. The sulfur compounds removed from the synthesis gas can be processed to produce sulfur or sulfuric acid.

[0103] In some embodiments, the green methane production process of biogas separation-biogas residue gasification coordinated with wind-solar electrolysis of water to produce hydrogen is as follows:

[0104] (1) anaerobic fermentation and biogas-biogas residue separation, (2) biogas separation and methane purification, (3) biogas residue treatment and gasification, (4) wind-solar power generation coupled with electrolysis of water to produce hydrogen, (5) gasification synthesis gas purification, the above processes are the same as the green methanol-green methane cogeneration process. Here is not described again.

[0105] (6) methane synthesis and purification

[0106] The purified gas is mixed with hydrogen produced by electrolysis of water, and the volume ratio of carbon monoxide to hydrogen is adjusted to about 1:3. The mixed gas is preheated and then sent into a methanation reactor. Under the action of the catalyst, carbon monoxide and hydrogen react in the reactor to generate methane and water. The reaction temperature and pressure must be strictly controlled to avoid overheating and deactivation of the catalyst. The gas mixture after the methanation reaction mainly contains methane, unreacted carbon monoxide and hydrogen, and water generated by the reaction, etc. After cooling, gas-liquid separation, and decarburization processes, the unreacted carbon monoxide and hydrogen are further separated and recycled back to the methanation reactor to improve the utilization rate of raw materials. Finally, the obtained gas is further dried to remove residual water, and high-purity green methane is obtained.

[0107] Further, taking a certain biogas station as an example, the station handles 300,000 tons of biomass and waste per year (containing about 50% water), and adopts the green methane-green methanol cogeneration process of biogas separation-biogas residue gasification coordinated with wind-solar electrolysis of water to produce hydrogen, and the specific implementation steps are as follows:

[0108] Biogas residue treatment and biogas separation: after biogas residue treatment, about 70,000 tons / year (dry basis), the biogas production rate of anaerobic digestion of biomass and waste is about 200 Nm 3 / ton (dry weight), the total biogas production is about 30,000,000 Nm 3 / year, the biogas composition is methane (65%) and carbon dioxide (35%), the direct purified methane yield is about 19,500,000 Nm 3 / year, and the amount of carbon dioxide is 10,500,000 Nm 3 / year.

[0109] Gasification of Residue: Assuming 1 Nm 3 Synthesis gas requires 0.50 Nm 3 of carbon dioxide, and 0.45 kg of residue, then all the carbon dioxide in the biogas is used as a gasification agent for residue gasification, and the amount of synthesis gas generated by gasification is 21,000,000 Nm 3 / year, and the composition of the synthesis gas is: carbon monoxide (50%), carbon dioxide (28%), and hydrogen (10%). The amount of carbon dioxide in the synthesis gas is 5,880,000 Nm 3 / year, and the amount of carbon dioxide in the biogas is 10,500,000 Nm 3 / year, for a total of 16,380,000 Nm 3 / year, of which 10,500,000 Nm 3 / year of carbon dioxide enters the gasifier as a gasification agent, and the remaining 5,880,000 Nm 3 / year of carbon dioxide is liquefied and produced.

[0110] Methanol synthesis and rectification process: The annual output of carbon monoxide and hydrogen in the synthesis gas is 10,500,000 Nm 3 and 2,100,000 Nm 3 , respectively. According to the volume ratio of carbon monoxide to hydrogen of 1:2, a mixed gas is formed for the synthesis of methanol, and 8,400,000 Nm 3 / year of hydrogen needs to be supplemented. The amount of synthesized methanol is approximately 16,140 tons per year.

[0111] Wind and solar power-driven hydrogen production process: The total demand for hydrogen is approximately 8,400,000 Nm 3 / year. Assuming that the electrolysis of water to produce hydrogen process generates 1 Nm 3 of hydrogen per 5 kWh of electricity, the total annual electricity consumption for the electrolysis of water to produce hydrogen is 42,000,000 kWh. Assuming that the available time for wind and solar power is 1200 hours per year, and the installed capacity of wind and solar power is approximately 35 MW.

[0112] A green methane production process that combines biogas separation, residue gasification, and wind-solar water electrolysis hydrogen production, with specific implementation steps as follows: Taking a certain biogas station that processes 300,000 tons of biomass and waste per year (with a water content of about 50%) as an example:

[0113] Residue treatment and biogas separation, residue gasification process, and green methanol production process are the same as described above, and will not be repeated.

[0114] Methane synthesis process: The annual output of carbon monoxide and hydrogen in the synthesis gas is 10,500,000 Nm 3 and 2,100,000 Nm 3, the hydrogen gas 10,400,000 Nm 3 / year needs to be supplemented. The amount of methane synthesized is 3,500,000 Nm 3 / year. The total amount of methane produced in this project is 23,000,000 Nm 3 / year.

[0115] The total demand for hydrogen gas is about 10,400,000 Nm 3 / year. Assuming that the electrolysis of water to produce hydrogen gas process consumes 5 kWh of electricity per Nm 3 of hydrogen gas, the total annual electricity consumption for the electrolysis of water to produce hydrogen gas is 52,000,000 kWh. Assuming that the wind and solar energy is available for 1,200 hours per year, the installed capacity of wind and solar power is about 44 MW.

[0116] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A green energy production process for biogas separation-biogas residue gasification combined with wind, solar, and water electrolysis to produce hydrogen, characterized in that, Includes the following steps: (1) Anaerobic fermentation of biomass or waste to produce biogas and biogas residue; (2) Separate biogas to obtain methane and carbon dioxide; (3) Hydrogen production by electrolyzing water using wind and solar green electricity; (4) Using carbon dioxide as a gasifying agent, biogas residue is gasified to generate syngas; (5) After purifying the synthesis gas, select any of the following processes: Cogeneration process: Syngas reacts with hydrogen to produce methanol, while the separated methane is used as a product; Single-product process: Syngas reacts with hydrogen to produce methane; (6) Unreacted gases are recycled and excess carbon dioxide is treated as a resource.

2. The green energy production process for biogas separation-biogas residue gasification combined with wind, solar, and water electrolysis to produce hydrogen according to claim 1, is characterized in that, The specific steps of the co-production process include: mixing the purified syngas with the hydrogen obtained in step (3) at a volume ratio of 1:2, synthesizing methanol under the action of a catalyst, and obtaining green methanol product after distillation and purification; at the same time, the methane separated in step (2) is directly used as green methane product. The specific steps of the single-production process include: mixing the purified syngas with the hydrogen obtained in step (3) at a volume ratio of 1:3, and carrying out a methanation reaction under the action of a catalyst to generate green methane products.

3. The green energy production process for biogas separation-biogas residue gasification combined with wind, solar, and water electrolysis to produce hydrogen according to claim 2, is characterized in that, The methanol synthesis reaction temperature of the co-production process is 200-300℃, and the pressure is 5-10MPa; The methanation reaction temperature of the single-yield process is 250-400℃, and the pressure is 3-8MPa.

4. The green energy production process for biogas separation-biogas residue gasification combined with wind, solar, and water electrolysis to produce hydrogen according to claim 1, characterized in that, In step (2), the biogas undergoes pretreatment and separation in sequence. The pretreatment includes water washing, desulfurization and drying, and the separation adopts pressure swing adsorption, membrane separation or absorption desorption technology.

5. The green energy production process for biogas separation-biogas residue gasification combined with wind, solar, and water electrolysis to produce hydrogen according to claim 1, characterized in that, In step (4), carbon dioxide is used as a gasifying agent in the digester residue gasification reaction, which increases the carbon monoxide content in the syngas and reduces carbon dioxide emissions. In step (4), the composition of the synthesis gas is: 40-60% carbon monoxide, 8-15% hydrogen, and 20-30% carbon dioxide.

6. The green energy production process for biogas separation-biogas residue gasification combined with wind, solar, and water electrolysis to produce hydrogen according to claim 1, characterized in that, In step (3), hydrogen production by water electrolysis is carried out using an alkaline electrolyzer or a PEM electrolyzer, and the hydrogen purity is ≥99.9%.

7. The green energy production process for biogas separation-biogas residue gasification combined with wind, solar, and water electrolysis to produce hydrogen according to claim 1, characterized in that, The purification of syngas in step (5) specifically includes dust removal, desulfurization and decarbonization treatment, and the removed sulfides are further processed into sulfur or sulfuric acid products.

8. The green energy production process for biogas separation-biogas residue gasification combined with wind, solar, and water electrolysis to produce hydrogen according to claim 1, characterized in that, In step (1), the raw material for anaerobic fermentation is biomass or urban organic waste, with a moisture content controlled at 30%-60%.

9. The green energy production process for biogas separation-biogas residue gasification combined with wind, solar, and water electrolysis to produce hydrogen according to claim 1, characterized in that, In step (6), the excess carbon dioxide is used as liquefied carbon dioxide product or supplementary gasification agent to achieve a closed-loop utilization of carbon resources.

10. The green energy production process for biogas separation-biogas residue gasification combined with wind, solar, and water electrolysis to produce hydrogen according to claim 1, characterized in that, The wind and solar power generation system includes wind turbine generators and solar photovoltaic panels. It uses a smart grid management system to smooth out power supply fluctuations and prioritizes power supply for hydrogen production via water electrolysis.

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