System and method for preparing hydrogen-rich synthesis gas through biogas residue gasification by taking biogas as composite gasifying agent

Abstract

The invention relates to a system and a method for preparing hydrogen-rich synthesis gas by gasifying biogas residues by taking biogas as a composite gasifying agent, and relates to the technical field of solid waste treatment. Comprising a biomass gradient anaerobic fermenter, a solid-liquid separation device, a drying reactor, a gasification reactor, a condensing tower and a synthesis gas purifier, the biomass gradient anaerobic fermenter is communicated with the drying reactor through a solid-liquid separation device, biogas residues are conveyed to the drying reactor, the drying reactor and the biomass gradient anaerobic fermenter are communicated with the gasification reactor, and biogas and the biogas residues dried by the drying reactor are input into the gasification reactor for reaction; the gasification reactor is communicated with the condensing tower, a reaction product is conveyed into the condensing tower, the condensing tower is communicated with the synthesis gas purifier, and gas cooled by the condensing tower is purified by the synthesis gas purifier to obtain hydrogen-rich synthesis gas. According to the invention, the biogas is used as a composite gasifying agent to gasify the biogas residue, so that the yield of hydrogen is obviously improved.

Description

Technical Field

[0001] The present invention relates to the technical field of solid waste treatment, and in particular to a system and method for preparing hydrogen-rich synthesis gas by gasifying biogas residue using biogas as a composite gasifying agent. Background Art

[0002] With the continuous growth of global energy demand and the improvement of environmental protection awareness, the development and utilization of biomass resources has gradually become an important way to achieve circular agriculture and low-carbon economy, and it is also an important contribution to achieving the goal of carbon neutrality. As a by-product of the fermentation process, biogas residue contains a certain amount of organic matter and nutrients, so it is regarded as a potential biomass resource and has a large volume in my country. However, the current treatment of biogas residue in my country has the following problems: (1) High moisture content and complex composition: The complex composition structure poses a challenge to the direct use of biogas residue. (2) High risk of environmental pollution: If it is not treated or treated improperly, biogas residue will become a source of pathogens and nutrients, causing serious pollution to water and soil. (3) Low resource utilization rate: Most biogas residues are still not effectively utilized as resources and are discarded.

[0003] Therefore, in order to circumvent the above problems in the process of biogas residue resource utilization, make full use of the organic matter in the biogas residue and improve the energy utilization efficiency after biogas residue gasification. Gasification technology is an efficient and safe biomass conversion technology that can efficiently convert biogas residue into valuable synthesis gas products. However, biomass gasification technology is affected by many factors, among which the type of gasifier has a crucial influence on the chemical reaction in the biomass gasification process.

[0004] Commonly used gasifiers include air, oxygen, carbon dioxide, and mixed gasifiers. Different gasifiers affect the composition of key combustible gas components (CH4, H2, CO, etc.) in syngas due to the difference in the content of functional elements such as C and H, which in turn affects the calorific value of the product gas. Air is the most widely used gasifier because of its low cost. However, the high nitrogen content in the air leads to a low calorific value of the syngas, and the high oxygen content makes the degree of gasification difficult to control. Oxygen gasification can reduce the dilution of nitrogen to a certain extent and increase the calorific value of the syngas, but the gas product is difficult to have hydrogen-rich characteristics. Carbon dioxide gasification requires the addition of steps to capture and purify carbon dioxide, which increases costs. Therefore, the currently developed biogas residue gasification technology cannot more efficiently convert biogas residue gasification into high-quality hydrogen-rich and carbon monoxide-rich syngas. In particular, the current urgent demand for clean fuels such as green methanol and jet fuel requires that biomass gasification syngas must have high hydrogen-rich characteristics. Therefore, it is crucial to develop a low-cost, easily available system and method that can use biogas as a composite gasifier to gasify biogas residue to prepare hydrogen-rich syngas. Summary of the invention

[0005] In order to solve at least one technical problem in the background technology, the present invention provides a system and method for preparing hydrogen-rich synthesis gas by gasifying biogas residue using biogas as a composite gasification agent. The biogas residue is gasified using biogas as a composite gasification agent, thereby achieving a significant increase in hydrogen yield.

[0006] To achieve the above-mentioned object, the present invention provides a system for preparing hydrogen-rich syngas by gasifying biogas residue using biogas as a composite gasifying agent, characterized in that it comprises: a biomass gradient anaerobic fermenter, a solid-liquid separation device, a drying reactor, a gasification reactor, a condensation tower and a syngas purifier;

[0007] The biomass gradient anaerobic fermenter is connected to the drying reactor through a solid-liquid separation device, and the separated biogas residue is transported to the drying reactor. The drying reactor and the biomass gradient anaerobic fermenter are respectively connected to the gasification reactor, and the biogas generated by the biomass gradient anaerobic fermenter and the biogas residue dried by the drying reactor are jointly input into the gasification reactor for reaction; the gasification reactor is connected to a condensing tower, and is used to transport the reaction product to the condensing tower. The condensing tower is connected to a synthesis gas purifier, and the gas cooled by the condensing tower is purified by the synthesis gas purifier to obtain hydrogen-rich synthesis gas.

[0008] Furthermore, it also includes a biogas collector and a biogas storage device, and the biomass gradient anaerobic fermenter is connected to the gasification reactor via the biogas collector and the biogas storage device in sequence.

[0009] Furthermore, it also includes a liquid waste collection device and a water resource treatment device. The solid-liquid separation device is sequentially connected to the liquid waste collection device and the water resource treatment device to collect and purify the separated biogas slurry.

[0010] A method for preparing hydrogen-rich syngas by gasifying biogas residue using biogas as a composite gasifying agent comprises the following steps:

[0011] Step S10, producing biogas through a biomass gradient anaerobic fermenter, and transporting the generated biogas to a gasification reactor;

[0012] Step S20, drying the biogas residue separated by the solid-liquid separation device in a drying reactor and then transporting it to a gasification reactor;

[0013] Step S30, the reaction product obtained by the gasification reactor is transported to a condensation tower, and the gas cooled by the condensation tower is purified by a synthesis gas purifier to obtain hydrogen-rich synthesis gas.

[0014] Furthermore, in step S10, biogas produced by the biomass gradient anaerobic fermenter is collected into a biogas storage device through a biogas collector, and the proportion of biogas and nitrogen in the gasification reactor is controlled.

[0015] Furthermore, the method further includes step S40, wherein the biogas slurry separated by the solid-liquid separation device is collected and purified by a liquid waste collection device and a water resource treatment device.

[0016] The beneficial effects of the present invention are:

[0017] The present invention aims at biogas residue, a typical biomass raw material that is difficult to utilize as a resource, in order to achieve efficient and clean utilization of biogas residue. It provides a system and method for preparing hydrogen-rich synthesis gas by gasifying biogas residue using biogas as a composite gasification agent. Biogas is used as a composite gasification agent to gasify the biogas residue, thereby achieving a significant increase in hydrogen yield. The biogas residue is consumed on-site by fermentation and further produced into hydrogen-rich synthesis gas, thereby improving the quality of the gas product, achieving efficient and clean thermochemical conversion of biomass biogas residue, and providing new ideas and technical references for the industrial application of biogas residue biomass. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a flow chart of the method of the present invention;

[0019] Figure 2 Schematic diagram of the distribution of gas products under different atmosphere conditions of the present invention;

[0020] Figure 3 Schematic diagram of H2 / CO and hydrogen yield under different atmosphere conditions of the present invention;

[0021] Figure 4 It is a schematic diagram of cooling efficiency of biogas residue gasification under different atmosphere conditions of the present invention;

[0022] Figure 5 Schematic diagram of the distribution of three-phase products of biogas residue gasification under different atmosphere conditions of the present invention;

[0023] Figure 6 This is a schematic diagram of the consumption of raw materials for hydrogen production according to the present invention. DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequential order. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present application described here. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0026] In the present application, the terms "upper", "lower", "left", "right", "front", "back", "top", "bottom", "inner", "outer", "middle", "vertical", "horizontal", "lateral", "longitudinal" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings. These terms are mainly used to better describe the present application and its embodiments, and are not used to limit the indicated devices, elements or components to have a specific orientation, or to be constructed and operated in a specific orientation.

[0027] In addition, some of the above terms may be used to express other meanings in addition to indicating orientation or positional relationship. For example, the term "on" may also be used to express a certain dependency or connection relationship in some cases. For those of ordinary skill in the art, the specific meanings of these terms in this application can be understood according to specific circumstances.

[0028] In addition, the terms "installed", "set", "provided with", "connected", "connected", and "socketed" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection, or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be an internal connection between two devices, elements, or components. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0029] To achieve the above purpose, Figure 1 As shown, the present invention provides a system for preparing hydrogen-rich syngas by gasifying biogas residue using biogas as a composite gasifying agent, characterized in that it comprises: a biomass gradient anaerobic fermenter, a solid-liquid separation device, a drying reactor, a gasification reactor, a condensation tower and a syngas purifier;

[0030] The biomass gradient anaerobic fermenter is connected to the drying reactor through a solid-liquid separation device, and the separated biogas residue is transported to the drying reactor. The drying reactor and the biomass gradient anaerobic fermenter are respectively connected to the gasification reactor, and the biogas generated by the biomass gradient anaerobic fermenter and the biogas residue dried by the drying reactor are jointly input into the gasification reactor for reaction; the gasification reactor is connected to a condensing tower, and is used to transport the reaction product to the condensing tower. The condensing tower is connected to a synthesis gas purifier, and the gas cooled by the condensing tower is purified by the synthesis gas purifier to obtain hydrogen-rich synthesis gas.

[0031] Furthermore, it also includes a biogas collector and a biogas storage device, and the biomass gradient anaerobic fermenter is connected to the gasification reactor via the biogas collector and the biogas storage device in sequence.

[0032] Furthermore, it also includes a liquid waste collection device and a water resource treatment device. The solid-liquid separation device is sequentially connected to the liquid waste collection device and the water resource treatment device to collect and purify the separated biogas slurry.

[0033] The main components of biogas are CH4, CO2, etc., among which CH4, as a hydrogen donor in the methanogenic reaction in the gasification reaction, can enhance the effect of biomass gasification and hydrogen production; at the same time, CO2, as a gasifying agent, can promote the Boudouard reaction to a certain extent, can significantly increase the CO production, provide a higher reaction temperature, faster reaction rate, a larger product range and higher thermal efficiency at the same molar ratio, and can obtain a higher calorific value of synthesis gas. Biogas and biogas residue are both products of anaerobic fermentation. The in-situ utilization of biogas through gasification can not only save energy consumption and loss in the biogas transportation process, realize on-site consumption, but also enhance the energy utilization of biogas residue. Therefore, biogas can be selected as an advantageous gasifying agent to achieve high-value conversion of biogas residue gasification.

[0034] In order to solve the problem of low efficiency in the treatment and energy utilization of biogas residue, the present invention utilizes part of the biogas from the biogas project to achieve resource-based treatment of biogas residue while improving the conversion rate of biomass into high-quality hydrogen-rich synthesis gas in the entire system. Traditional gasification methods, such as pure nitrogen gasification and CO2 gasification, have the defects of low hydrogen yield and low energy utilization efficiency. Therefore, the present invention provides a system for preparing hydrogen-rich synthesis gas by gasifying biogas residue using biogas as a composite gasification agent. The system can effectively improve the gasification efficiency of biogas residue and the yields of H2 and CO, and can ensure experimental safety. The present invention has the characteristics of high efficiency, cost saving, and environmental friendliness, and therefore has good market application value.

[0035] The present invention also provides a method for preparing hydrogen-rich synthesis gas by gasifying biogas residue using biogas as a composite gasifying agent, comprising the following steps:

[0036] Step S10, producing biogas through a biomass gradient anaerobic fermenter, and transporting the generated biogas to a gasification reactor;

[0037] Step S20, drying the biogas residue separated by the solid-liquid separation device in a drying reactor and then transporting it to a gasification reactor;

[0038] Step S30, the reaction product obtained by the gasification reactor is transported to a condensation tower, and the gas cooled by the condensation tower is purified by a synthesis gas purifier to obtain hydrogen-rich synthesis gas.

[0039] Furthermore, in step S10, biogas produced by the biomass gradient anaerobic fermenter is collected into a biogas storage device through a biogas collector, and the proportion of biogas and nitrogen in the gasification reactor is controlled.

[0040] Furthermore, the method further includes step S40, wherein the biogas slurry separated by the solid-liquid separation device is collected and purified by a liquid waste collection device and a water resource treatment device.

[0041] The present invention has the following advantages:

[0042] Utilizing biogas as a composite gasifying agent: The present invention proposes to use biogas as a composite gasifying agent in the gasification process. Compared with traditional gasifying agents such as air, oxygen or water vapor, the introduction of biogas not only effectively utilizes resources and reduces waste gas emissions, but also significantly increases the hydrogen yield in the gasification process through its high methane content. In addition, the use of biogas can reduce dependence on external gasifying agents and achieve more economical operation. The present invention found that the hydrogen yield under biogas gasification was increased by 50.8% over the hydrogen yield under pure nitrogen gasification and by 40.3% over the hydrogen yield under CO2 atmosphere. In addition, the H2 / CO ratio of the synthesis gas produced under a biogas atmosphere is 1.55 to 1.96 times the H2 / CO ratio under CO2 gasification.

[0043] Improved hydrogen production: Biogas slag gasification usually limits hydrogen production due to its low carbon-hydrogen ratio. The present invention uses the methane content in biogas as an additional hydrogen source, which not only promotes the deep gasification of biogas slag, but also enhances the hydrogen production, thereby generating hydrogen-rich synthesis gas, thereby improving the application potential of this technology in hydrogen energy production.

[0044] System integration and efficient gasification process design: The biogas gasification system developed by the present invention has significant advantages in energy efficiency. The system design fully considers the supply and control of biogas, optimizes the gasification reaction conditions, and ensures the high efficiency and stability of the gasification reaction. Through efficient reactor structure design and heat exchange technology, the system can realize the self-circulation of energy, improve the overall efficiency, and reduce energy consumption. The results show that the cooling efficiency under biogas atmosphere is 2.39 to 3.06 times that of CO2 gasification.

[0045] Optimization of biogas products: The biogas gasification system of the present invention has a significant impact on the gas composition and three-phase product distribution in the biogas products. The system design can optimize the gas composition, increase the yield of useful gas, and improve the distribution characteristics of the three-phase products.

[0046] Co-optimization of gas purification and hydrogen-rich syngas preparation: This approach not only focuses on hydrogen generation during the gasification process, but also significantly reduces the content of impurity gases such as carbon dioxide and carbon monoxide through subsequent gas purification technology, thereby improving the quality of syngas and making it more suitable for downstream industrial applications such as chemical synthesis and the preparation of green jet fuel.

[0047] The significant advantages of biogas gasification of sludge are explained in detail below.

[0048] 1. The thermal properties of the product gas can be improved under biogas atmosphere, so that the H2 and CO content can be significantly increased, which can improve the gas quality, such as Figure 2 (a) Figure 2 (b) and Figure 3 (a) Figure 3 (b) The proportion of combustible components (such as H2, CO) in the syngas is high, and the fuel value is high. The purity of the syngas is high: there are fewer impurities in the syngas, which increases its application value in subsequent processes, such as fuel cells or chemical synthesis.

[0049] 2. The biogasification of biogas residue has significant advantages in energy utilization efficiency. Figure 4 It can be seen that the cooling efficiency of biogas gasification is significantly higher than that of CO2 gasification, so more raw material energy is successfully converted into chemical energy in the synthesis gas instead of being wasted. This shows that: the energy loss during the reaction is small, and the heat loss and unreacted carbon loss during the gasification process are small. The reaction is more efficient, and the reaction conditions (such as temperature, pressure, and gasification agent ratio) are well optimized, which promotes the complete gasification and efficient conversion of the raw materials.

[0050] 3. The gasification products of biogas residue in biogas atmosphere have significant advantages. The gas production of biogas gasification products is stable between 59% and 61%, which is consistent with the gas production ratio under CO2 atmosphere. Figure 5 (a) Figure 5 As shown in (b), the gas produced under biogas atmosphere has higher performance. In addition, in biogas gasification, the tar production is lower, from 3% to 1%. Low tar production means that the complex organic matter that needs to be treated during the gasification process is reduced, which helps to improve the operational stability and efficiency of the system. Because the CO2 in the biogas can promote the partial oxidation reaction of carbon to produce carbon monoxide during the gasification process, while avoiding the production of excessive tar. The biochar production is between 38% and 40%, fluctuating slightly but remaining stable. This shows that the biogas gasification process has little effect on the formation of solid carbon, and can provide a stable biochar output for further processing and utilization. Because in the biogas atmosphere, the partial oxidation of carbon and the reforming reaction of methane are balanced, making the generation of biochar relatively stable. This feature helps to provide a continuous output of solid products, which is convenient for further utilization of carbon-based materials, such as soil improvement or carbon capture.

[0051] 4. Under the condition of biogas atmosphere, the same 1g of hydrogen is produced with less raw material consumption. Figure 6 . When producing products of the same quality, there is a close relationship between the amount of raw material consumption and environmental benefits. Less raw material consumption usually means higher resource efficiency. It not only reduces the exploitation and consumption of natural resources, but also reduces the environmental impact associated with the acquisition of raw materials, so it has positive environmental benefits. At the same time, it can reduce the energy consumption required for raw material extraction and fermentation, thereby reducing greenhouse gas emissions and other pollutants. Reducing the consumption of raw materials can reduce the environmental impact of the entire production cycle, including global warming potential, acidification potential and eutrophication potential. Therefore, reducing the consumption of raw materials when producing products of the same quality can bring significant environmental benefits, which not only helps to protect natural resources and the ecological environment, but also meets the goals of sustainable development and circular economy. Reducing the consumption of raw materials has achieved the effect of further reducing the cost of the production stage and improving economic benefits.

[0052] The above description is only a preferred embodiment of the present invention and does not limit the technical scope of the present invention. Therefore, any slight modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A system for preparing hydrogen-rich syngas by gasifying biogas residue using biogas as a composite gasifying agent, characterized in that: include: Biomass gradient anaerobic fermenter, solid-liquid separation device, drying reactor, gasification reactor, condensation tower and syngas purifier; The biomass gradient anaerobic fermenter is connected to the drying reactor through a solid-liquid separation device, and the separated biogas residue is transported to the drying reactor. The drying reactor and the biomass gradient anaerobic fermenter are respectively connected to the gasification reactor, and the biogas generated by the biomass gradient anaerobic fermenter and the biogas residue dried by the drying reactor are jointly input into the gasification reactor for reaction; the gasification reactor is connected to a condensing tower, and is used to transport the reaction product to the condensing tower. The condensing tower is connected to a synthesis gas purifier, and the gas cooled by the condensing tower is purified by the synthesis gas purifier to obtain hydrogen-rich synthesis gas.

2. A system for preparing hydrogen-rich syngas by gasifying biogas residue using biogas as a composite gasifying agent as claimed in claim 1, characterized in that: It also includes a biogas collector and a biogas storage device. The biomass gradient anaerobic fermenter is connected with the gasification reactor via the biogas collector and the biogas storage device in sequence.

3. A system for preparing hydrogen-rich syngas by gasifying biogas residue using biogas as a composite gasifying agent as claimed in claim 1 or 2, characterized in that: It also includes a liquid waste collection device and a water resource treatment device. The solid-liquid separation device is sequentially connected to the liquid waste collection device and the water resource treatment device to collect and purify the separated biogas slurry.

4. A method for preparing hydrogen-rich syngas by gasifying biogas residue using biogas as a composite gasifying agent, characterized in that: The steps include: Step S10, producing biogas through a biomass gradient anaerobic fermenter, and transporting the generated biogas to a gasification reactor; Step S20, drying the biogas residue separated by the solid-liquid separation device in a drying reactor and then transporting it to a gasification reactor; Step S30, the reaction product obtained by the gasification reactor is transported to a condensation tower, and the gas cooled by the condensation tower is purified by a synthesis gas purifier to obtain hydrogen-rich synthesis gas.

5. The method for preparing hydrogen-rich synthesis gas by gasifying biogas residue using biogas as a composite gasifying agent as claimed in claim 4, characterized in that: In step S10, biogas produced by the biomass gradient anaerobic fermenter is collected in a biogas storage device through a biogas collector, and the proportion of biogas and nitrogen in the gasification reactor is controlled.

6. A method for preparing hydrogen-rich synthesis gas by gasifying biogas residue using biogas as a composite gasifying agent as claimed in claim 4 or 5, characterized in that: The method further includes step S40, wherein the biogas slurry separated by the solid-liquid separation device is collected and purified by a liquid waste collection device and a water resource treatment device.

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