Integrated anaerobic fermentation self-heating biogas production system and method

Abstract

The invention discloses an integrated anaerobic fermentation self-heating biogas production system and method, and belongs to the technical field of biomass energy. In the system disclosed by the invention, a thermal medium outlet of a solar heat collection unit is connected with a thermal medium inlet of a heat storage unit; a heat medium outlet of the heat storage unit is connected with a heat medium inlet of the anaerobic fermentation unit; a gas outlet of the anaerobic fermentation unit is respectively connected with the post-treatment system and the torch incineration device; a natural gas outlet of the post-treatment system is connected with the torch incineration device; a waste heat outlet of the post-treatment system is connected with a thermal medium inlet of the anaerobic fermentation unit; a cold medium outlet of the anaerobic fermentation unit is connected with a cold medium inlet of the heat storage unit; and a cold medium outlet of the heat storage unit is connected with a cold medium inlet of the solar heat collection unit. The system solves the technical problem that an existing method is high in energy consumption and difficult to achieve efficient operation of the whole system.

Description

Technical Field

[0001] The present invention belongs to the technical field of biomass energy, and particularly relates to an integrated anaerobic fermentation self-heating system and method for producing biomethane. Background Art

[0002] Anaerobic fermentation technology is a process of using microorganisms to decompose organic substances under anaerobic conditions to produce biogas. The main components of biogas are methane (CH4) and carbon dioxide (CO2), and it also contains a small amount of hydrogen sulfide (H2S), nitrogen (N2) and other trace gases. After purification and refinement, biogas can obtain high-purity biomethane, whose composition is similar to that of fossil natural gas and can be directly used for power generation, heating or as vehicle fuel. Anaerobic fermentation technology can not only effectively treat organic waste, but also produce clean energy. Therefore, it has been widely used in the fields of agricultural, industrial and municipal waste treatment.

[0003] Anaerobic fermentation is a complex biochemical process of urban and rural organic waste, which is usually divided into four stages: hydrolysis, acidification, acetification and methanation. In the hydrolysis stage, urban and rural organic waste is decomposed by microorganisms into simple soluble substances; in the acidification stage, these soluble substances are further converted into volatile fatty acids (such as acetic acid, propionic acid and butyric acid); in the acetification stage, volatile fatty acids are converted into acetic acid, hydrogen and carbon dioxide; finally, in the methanation stage, acetic acid and hydrogen are converted into methane and carbon dioxide by methanogens. The efficiency of anaerobic fermentation is affected by various factors, including temperature, pH value, organic load, stirring intensity and the design of the fermentation tank, etc. Among them, temperature is one of the key factors affecting fermentation efficiency. According to the suitable growth temperature of microorganisms, anaerobic fermentation can be divided into mesophilic fermentation (30 - 40 °C) and thermophilic fermentation (50 - 60 °C). In order to maintain the suitable temperature in the fermentation tank, external energy supply is usually required, which increases the operating cost of the system.

[0004] Although anaerobic fermentation technology plays an important role in biogas production, there are still some limitations in its practical application: 1) High energy consumption: Traditional anaerobic fermentation tanks require external energy supply to maintain the temperature and stirring operation inside the fermentation tank. Especially in cold regions, the heat supply energy consumption is high, resulting in increased production costs; 2) Waste of waste heat: A large amount of waste heat is generated during the biogas purification and biogas compression processes, but this waste heat is usually not effectively utilized and is directly discharged into the environment, causing energy waste; 3) Low system integration: Existing biogas purification and biogas compression systems mostly operate independently, lacking system integration, resulting in large equipment floor areas and low operating efficiency; 4) Carbon dioxide emission problem: Biogas contains a large amount of carbon dioxide, and traditional purification and purification systems usually directly discharge carbon dioxide into the atmosphere, increasing greenhouse gas emissions; 5) Complex equipment and high costs: The equipment of traditional anaerobic fermentation systems is complex, and the installation and maintenance costs are relatively high, restricting the popularization and application of the technology.

[0005] To overcome the limitations of traditional anaerobic fermentation technology, some technologies in the current industry have made various improvement attempts, mainly including the following aspects: 1) Cogeneration technology: Cogeneration technology is a technology that uses the waste heat generated during the power generation process for heating, and has been applied in some anaerobic fermentation systems. For example, while using a gas generator to generate electricity, the waste heat generated is recovered for heating the fermentation tank. However, this technology usually relies on fossil fuels and fails to fully realize the utilization of clean energy; 2) Waste heat recovery technology: Some studies have tried to recover the waste heat generated during the biogas purification and natural gas compression processes through heat exchangers and use it for heating the fermentation tank. However, these technologies usually only target the waste heat recovery of a single link and fail to achieve the overall optimization of the system; 3) Carbon dioxide capture and utilization technology: In order to reduce carbon dioxide emissions, some studies have tried to capture and convert the carbon dioxide in biogas into high-value products, such as liquid carbon dioxide or chemicals. However, these technologies usually require additional equipment and energy input, increasing the complexity and cost of the system; 4) System integration technology: Some enterprises have tried to integrate the biogas purification system and the natural gas compression system for integrated design to reduce the equipment floor area and improve the operating efficiency. However, these integrated designs usually lack a comprehensive consideration of waste heat recovery and carbon dioxide utilization. Summary of the Invention

[0006] The object of the present invention is to provide an integrated anaerobic fermentation self-heating biogas production system and method to solve the technical problem that the existing method has high energy consumption and it is difficult to achieve the efficient operation of the overall system.

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

[0008] The present invention discloses an integrated anaerobic fermentation self-heating biogas production system, which includes a solar heat collection unit, a heat storage unit, an anaerobic fermentation unit, a post-treatment system and a flare incineration device; the heat medium outlet of the solar heat collection unit is connected to the heat medium inlet of the heat storage unit; the heat medium outlet of the heat storage unit is connected to the heat medium inlet of the anaerobic fermentation unit; the gas outlet of the anaerobic fermentation unit is respectively connected to the post-treatment system and the flare incineration device; the biogas outlet of the post-treatment system is connected to the flare incineration device; the waste heat outlet of the post-treatment system is connected to the heat medium inlet of the anaerobic fermentation unit; the cold medium outlet of the anaerobic fermentation unit is connected to the cold medium inlet of the heat storage unit; the cold medium outlet of the heat storage unit is connected to the cold medium inlet of the solar heat collection unit.

[0009] Further, the solar heat collection unit includes a number of serially connected solar collectors; the heat storage unit is a heat storage tank; the anaerobic fermentation unit includes a number of serially connected anaerobic fermentation tanks; the hot water outlets of the number of solar collectors are connected and then connected to the heat medium inlet of the heat storage tank; the heat medium outlet of the heat storage tank (4) is connected to the heat medium inlets of the number of anaerobic fermentation tanks through a pipeline; the biogas outlets of the number of anaerobic fermentation tanks are connected to the flare incineration device; the biogas outlets of the number of anaerobic fermentation tanks are connected to the post-treatment system; the heat medium outlets of the number of anaerobic fermentation tanks are connected to the cold medium inlet of the heat storage tank; the cold medium outlet of the heat storage tank is connected to the cold medium inlet of the solar collector.

[0010] Further, the post-treatment system includes a purification device, a gas compression device connected in sequence, and a carbon dioxide liquefaction system connected to the purification device; a carbon dioxide liquefaction device is arranged inside the carbon dioxide liquefaction system;

[0011] The biogas outlets of the number of anaerobic fermentation tanks are connected to the gas inlet of the purification device, the biogas outlet of the purification device is connected to the gas inlet of the gas compression device, and the gas outlet of the gas compression device is connected to the flare incineration device; the waste heat outlets of the purification device and the gas compression device are connected to the heat medium inlets of the number of anaerobic fermentation tanks; the carbon dioxide outlet of the purification device is connected to the carbon dioxide inlet of the carbon dioxide liquefaction system;

[0012] One end of the carbon dioxide liquefaction device is connected to the carbon dioxide inlet through a fourth stop valve, and the other end is connected to the liquid carbon dioxide outlet of the carbon dioxide liquefaction system through a third stop valve.

[0013] Further, the waste heat outlets of the purification device and the gas compression device are connected to the heat medium inlets of the number of anaerobic fermentation tanks through a heat exchanger.

[0014] Further, the purification device includes a dehydration device, a desulfurization device, and a decarburization device connected in sequence; the gas inlet of the dehydration device is connected to the natural gas outlets of a number of anaerobic fermentation tanks; the carbon dioxide outlet of the decarburization device is connected to the carbon dioxide inlet of the carbon dioxide liquefaction system; the gas outlet of the decarburization device is connected to the gas inlet of the gas compression device.

[0015] Further, the gas compression device includes a fifth stop valve, a compressor, and a sixth stop valve connected in sequence; the fifth stop valve is connected to the gas outlet of the purification device through a pipeline; the sixth stop valve is connected to the flare incineration device through a pipeline.

[0016] Further, the flare incineration device includes a second stop valve, a pressure regulating valve, a biogas inlet, and a natural gas inlet; the biogas inlet and the natural gas inlet are respectively arranged at the upper and lower ends of the flare incineration device; the gas outlet of the gas compression device is connected to the natural gas inlet through the second stop valve and the pressure regulating valve in sequence; the biogas outlets of the number of anaerobic fermentation tanks are connected to the biogas inlet.

[0017] Further, a first stop valve is arranged on the pipeline connecting the biogas outlets of the number of anaerobic fermentation tanks and the biogas inlet.

[0018] Further, heating coils are arranged in the anaerobic fermentation tank.

[0019] The present invention also discloses a usage method of the above integrated anaerobic fermentation self-heating biogas production system, including the following steps:

[0020] Convert the solar energy collected by the solar heat collection unit into heat energy and store it in the heat storage unit, and the heat storage unit transports the heat energy to the anaerobic fermentation unit to provide heat source for the anaerobic fermentation process. Subsequently, the gas obtained after anaerobic fermentation in the anaerobic fermentation unit is respectively transported to the flare incineration device and the post-treatment system; after the post-treatment system processes the gas, natural gas and liquid carbon dioxide are obtained, and the obtained natural gas is transported to the flare incineration device.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The present invention discloses an integrated anaerobic fermentation self-heating system for producing biomethane. By setting up a solar heat collection unit, a heat storage unit, an anaerobic fermentation unit, a post-treatment system and a flare incineration device, the solar energy absorbed by the solar heat collection unit is converted into heat energy and stored in the heat storage unit, and then a stable heat source is provided for the anaerobic fermentation process in the anaerobic fermentation unit. This system adopts the self-heating method using solar energy, significantly reducing the dependence on external energy in the traditional fermentation process. At the same time, clean energy is used to reduce carbon emissions. The adoption of the heat storage unit realizes the temperature stability of the anaerobic fermentation process. The setting of the post-treatment system ensures the recovery and reuse benefits of carbon dioxide generated during the anaerobic fermentation process. The connection between the waste heat outlet of the post-treatment system and the heat medium inlet of the anaerobic fermentation unit, and the connection between the cold medium outlet of the heat storage unit and the cold medium inlet of the solar heat collection unit realize the efficient recovery and utilization of waste heat during the operation of the whole system. The multiple recycling of cold water significantly reduces water resource consumption, solving the technical problem that the existing methods have high energy consumption and it is difficult to achieve the efficient operation of the overall system.

[0023] Furthermore, the post-treatment system is provided with a purification device, a gas compression device and a carbon dioxide liquefaction system. The purification device and the gas compression device separate and liquefy carbon dioxide in biogas into high-purity liquid carbon dioxide through separation, compression and cooling processes. The collected liquid carbon dioxide is stored in a special storage tank and can be used for food processing, industrial cooling or as a chemical raw material, significantly increasing the added value of the product. Through modular design, this system realizes the efficient separation and liquefaction of carbon dioxide, while reducing the equipment floor area and operating costs. The present invention is applicable to the fields of biogas engineering and carbon dioxide recovery and utilization, and has the advantages of high efficiency, economy and environmental protection.

[0024] Furthermore, this system can share the vent riser for biogas purification and biomethane compression. The vented compressed biomethane is depressurized by a pressure reducing device and then transported to the flare incineration device for incineration treatment. Through the shared design of the vent riser, the equipment floor area and construction costs are reduced. At the same time, environmental pollution caused by the direct emission of vent gas is avoided through flare incineration.

[0025] Furthermore, the system combines the purification and upgrading of biogas, the compression of natural gas, and the liquefaction of carbon dioxide in a joint design to form a highly integrated integrated unit. By optimizing the process flow, this unit reduces the energy loss and material transfer loss between equipment. At the same time, through an integrated control platform, it realizes the intelligent linkage control of each system; the integrated unit adopts a modular design, which is convenient for installation, maintenance, and expansion, and is applicable to biogas projects of different scales; through the joint design, the present invention significantly improves the overall efficiency of the system, reduces the operating cost, and has the advantages of high efficiency, energy conservation, and economy; according to relevant experimental results, the solar heating of the present invention can reduce energy consumption by 30%-50%, the heat preservation efficiency of the heat storage tank reaches more than 90%, ensuring that the fermentation temperature is stable within the range of 35-40°C, especially suitable for areas with sufficient sunlight, and saving about 20%-40% of the annual energy cost; the utilization rate of the cold water circulation reaches more than 95%, saving about 30%-50% of the annual water consumption. At the same time, using solar energy to heat cold water reduces energy consumption by 20%-30%, especially suitable for areas with water shortages; the waste heat recovery rate can reach 60%-80%, saving about 15%-25% of the annual energy cost, and reducing heat pollution emissions by 30%-40% at the same time, significantly improving the energy utilization efficiency and environmental protection benefits; the carbon dioxide recovery rate is as high as more than 90%, and thousands of tons of high-purity liquid carbon dioxide can be produced annually, increasing the income by about 10%-20%, and reducing carbon emissions by 30%-50% at the same time, having significant economic and environmental benefits; the floor area of the equipment is reduced by 20%-30%, the construction cost is reduced by 15%-25%, and at the same time, the vent gas is treated by flare incineration, reducing harmful gas emissions by 50%-70%, significantly improving the environmental protection benefits; the energy loss is reduced by 20%-30%, the equipment investment cost is reduced by 15%-20%, the operating efficiency is increased by 25%-35%, and at the same time, through the intelligent control platform, the linkage of each system is realized, significantly improving the overall efficiency and economic benefits of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the overall structure of the integrated anaerobic fermentation self-heating biogas production system in the embodiment of the present invention;

[0027] Wherein: 1 - first solar collector; 101 - first cold water inlet; 2 - second solar collector; 201 - second cold water inlet; 3 - third solar collector; 301 - third cold water inlet; 302 - hot water outlet; 4 - heat storage tank; 401 - heat storage tank hot water inlet; 402 - heat storage tank cold water outlet; 403 - heat storage tank hot water outlet; 404 - heat storage tank cold water inlet; 5 - first anaerobic fermentation tank; 501 - first anaerobic fermentation cold water outlet; 502 - first biogas vent; 503 - first anaerobic fermentation hot water inlet; 504 - first day biogas outlet; 6 - second anaerobic fermentation tank; 601 - second anaerobic fermentation cold water outlet; 602 - second biogas vent; 603 - second anaerobic fermentation hot water inlet; 604 - second biogas outlet; 7 - dehydration device; 8 - desulfurization device; 9 - decarbonization device; 10 - purification device; 1001 - purification device biogas inlet; 1002 - purification device biogas vent; 1003 - purification device waste heat outlet; 1004 - carbon dioxide outlet; 1005 - purified natural gas outlet of the purification device; 11 - fifth stop valve; 12 - compressor; 13 - sixth stop valve; 14 - gas compression device; 1401 - natural gas inlet of the compression device; 1402 - waste heat outlet of the compression device; 1403 - natural gas vent of the compression device; 1404 - natural gas outlet of the compression device; 15 - carbon dioxide liquefaction device; 16 - third stop valve; 17 - fourth stop valve; 18 - carbon dioxide liquefaction system; 1801 - carbon dioxide inlet; 1802 - liquid carbon dioxide outlet; 19 - first stop valve; 20 - second stop valve; 21 - pressure regulating valve; 2201 - biogas inlet; 2202 - natural gas inlet; 22 - flare incineration device. Detailed implementation manners

[0028] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0029] It should be noted that the terms "first", "second", etc. in the description, claims and the above drawings of the present invention are used to distinguish similar objects, and do not necessarily describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances, so that the embodiments of the present invention described here can be implemented in an order other than those illustrated or described here. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device comprising a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0030] The present invention discloses an integrated anaerobic fermentation self-heating biogas production system. By setting up a solar heat collection unit, a heat storage unit, an anaerobic fermentation unit, a post-treatment system and a flare incineration device 22, the solar energy absorbed by the solar heat collection unit is converted into heat energy and stored in the heat storage unit in the form of hot water. Subsequently, the heat storage unit is connected to the anaerobic fermentation unit through a circulation pump, and the hot water is transported to the anaerobic fermentation unit to provide a stable heat source for the anaerobic fermentation process. Through the self-heating method of solar energy, this system significantly reduces the dependence on external energy in the traditional fermentation process, and at the same time uses clean energy to reduce carbon emissions.

[0031] Specifically, the solar heat collection unit includes a number of serially connected solar collectors; the heat storage unit is a heat storage tank 4; the anaerobic fermentation unit includes a number of serially connected anaerobic fermentation tanks; the hot water outlets of the solar collectors are connected and then connected to the heat medium inlet of the heat storage tank 4; the heat medium outlet of the heat storage tank 4 is connected to the heat medium inlets of the anaerobic fermentation tanks through pipelines; the biogas outlets of the anaerobic fermentation tanks are connected to the flare incineration device 22; the natural gas outlets of the anaerobic fermentation tanks are connected to the post-treatment system; the heat medium outlets of the anaerobic fermentation tanks are connected to the cold medium inlet of the heat storage tank 4; the cold medium outlet of the heat storage tank 4 is connected to the cold medium inlet of the solar collector. The cold water in the anaerobic fermentation tank is transported to the heat storage tank 4 through a pipeline, and then sent to the solar collector for heating through a circulation water pump. The heated hot water returns to the anaerobic fermentation tank again, forming a closed cycle. Through the multiple recycling of cold water, the consumption of water resources is significantly reduced, and at the same time, the waste of resources and environmental pollution caused by the direct discharge of cold water in the traditional process are avoided. In addition, this system can also monitor the water temperature in real time through an intelligent temperature control device to ensure the maximum heating efficiency of cold water. It is suitable for large-scale anaerobic fermentation projects and has the advantages of water saving, energy saving and environmental protection, especially suitable for areas with water shortages.

[0032] Specifically, the post-treatment system includes a skid-mounted purification device 10, a skid-mounted gas compression device 14 connected in sequence, and a skid-mounted carbon dioxide liquefaction system 18 connected to the purification device 10; a carbon dioxide liquefaction device 15 is arranged inside the carbon dioxide liquefaction system 18; the waste heat outlets of the purification device 10 and the gas compression device 14 are connected to the heat medium inlets of a number of anaerobic fermentation tanks through a heat exchanger; the waste heat generated during the production process of the biogas purification and upgrading system and the natural gas compression system is recovered through a heat exchanger, and the recovered heat energy is transported to the anaerobic fermentation tanks through pipelines to provide an auxiliary heat source for the fermentation process. Through the recovery and utilization of waste heat, the comprehensive utilization efficiency of energy is significantly improved, and the energy waste caused by the direct discharge of waste heat in the traditional process is reduced. In addition, the system is equipped with an intelligent control device, which can automatically adjust the waste heat supply according to the heat demand of the fermentation tank to ensure the stability of the fermentation temperature; the present invention is applicable to the fields of biogas engineering and natural gas processing, and has the characteristics of high efficiency, energy conservation and environmental protection.

[0033] Specifically, the natural gas outlets of a number of anaerobic fermentation tanks are connected to the gas inlet of the purification device 10. The natural gas outlet 1005 of the purification device is connected to the gas inlet of the gas compression device 14. The gas outlet of the gas compression device 14 is connected to the flare incineration device 22. The waste heat outlets of the purification device 10 and the gas compression device 14 are connected to the heat medium inlets of a number of anaerobic fermentation tanks. The carbon dioxide outlet 1004 of the purification device 10 is connected to the carbon dioxide inlet 1801 of the carbon dioxide liquefaction system 18. One end of the carbon dioxide liquefaction device 15 is connected to the carbon dioxide inlet 1801 through the fourth stop valve 17, and the other end is connected to the liquid carbon dioxide outlet 1802 of the carbon dioxide liquefaction system 18 through the third stop valve 16. The purification device 10 includes a dehydration device 7, a desulfurization device 8, and a decarbonization device 9 connected in sequence. The gas inlet of the dehydration device 7 is connected to the natural gas outlets of a number of anaerobic fermentation tanks. The carbon dioxide outlet 1004 of the decarbonization device 9 is connected to the carbon dioxide inlet 1801 of the carbon dioxide liquefaction system 18. The gas outlet of the decarbonization device 9 is connected to the gas inlet of the gas compression device 14. The gas compression device 14 includes a fifth stop valve 11, a compressor 12, and a sixth stop valve 13 connected in sequence. The fifth stop valve 11 is connected to the gas outlet of the purification device 10 through a pipeline. The sixth stop valve is connected to the flare incineration device 22 through a pipeline. By integrating the purification and upgrading of biogas (dehydration, decarbonization, and desulfurization) and a skid-mounted carbon dioxide liquefaction device, the carbon dioxide in the biogas is separated and liquefied into high-purity liquid carbon dioxide. The liquid carbon dioxide is stored in a special storage tank and can be used for food processing, industrial cooling, or as a chemical raw material, significantly increasing the added value of the product. Through modular design, this system realizes the efficient separation and liquefaction of carbon dioxide, while reducing the floor area of equipment and operating costs. It is applicable to the fields of biogas projects and carbon dioxide recovery and utilization, and has the advantages of high efficiency, economy, and environmental protection.

[0034] Specifically, the torch incineration device 22 includes a second shut-off valve 20, a pressure regulating valve 21, a biogas inlet 2201 and a natural gas inlet 2202; the biogas inlet 2201 and the natural gas inlet 2202 are respectively arranged at the upper and lower ends of the torch incineration device 22; the gas outlet of the gas compression device 14 is connected to the natural gas inlet 2202 through the second shut-off valve 20 and the pressure regulating valve 21 in sequence; the biogas outlets of the plurality of anaerobic fermentation tanks are connected to the biogas inlet 2201; a first shut-off valve 19 is arranged on the pipeline connecting the biogas outlets of the plurality of anaerobic fermentation tanks and the biogas inlet 2201; by sharing the vent riser of the biogas purification and upgrading system and the biomethane compression system, the decompression device reduces the pressure of the vented compressed biomethane and then transports it to the torch incineration device 22 for incineration treatment. Through the shared design of the vent riser, the floor area of the equipment and the construction cost are reduced. At the same time, the direct emission of the vent gas is avoided through torch incineration, thus preventing environmental pollution; in addition, the system can be equipped with a gas monitoring device to monitor the composition and flow rate of the vent gas in real time, ensuring the safety and environmental protection of the incineration process; it is applicable to the biogas project and natural gas processing fields and has the advantages of energy conservation, environmental protection and safety.

[0035] This system can achieve the integrated control of biogas purification and upgrading, natural gas compression and carbon dioxide liquefaction. Through the combined design of biogas purification and upgrading, natural gas compression and carbon dioxide liquefaction, a highly integrated integrated combined system is formed; by optimizing the process flow, this system reduces the energy loss and material transmission loss between equipment. At the same time, the intelligent linkage control of each system is realized through the integrated control platform. The combined device adopts a modular design, which is convenient for installation, maintenance and expansion and is applicable to biogas projects of different scales. Through the combined design, the overall efficiency of the system is significantly improved and the operating cost is reduced in the present invention, which has the advantages of high efficiency, energy conservation and economy.

[0036] The present invention will be further described in detail below with reference to the accompanying drawings:

[0037] Embodiment 1

[0038] As Figure 1As shown, in this embodiment, the solar heat collection unit includes a first solar collector 1, a second solar collector 2, and a third solar collector 3; the heat storage unit is a heat storage tank 4; the anaerobic fermentation unit includes a first anaerobic fermentation tank 5 and a second anaerobic fermentation tank 6; the post-treatment system includes a purification device 10, a gas compression device 14, and a carbon dioxide liquefaction system 18; a dehydration device 7, a desulfurization device 8, and a decarburization device 9 are sequentially arranged in the purification device 10; a compressor 12 is arranged inside the gas compression device 14; a carbon dioxide liquefaction device 15 is arranged in the carbon dioxide liquefaction system 18; the above devices jointly integrate biogas purification and purification, natural gas compression, and carbon dioxide liquefaction; after the first solar collector 1, the second solar collector 2, and the third solar collector 3 are connected in series, the hot water outlet 302 on the third solar collector 3 is connected to the heat storage tank hot water inlet 401 of the heat storage tank 4 through a pipeline; the heat storage tank hot water outlet 403 is respectively connected to the first anaerobic fermentation hot water inlet 503 of the first anaerobic fermentation tank 5 and the second anaerobic fermentation hot water inlet 603 of the second anaerobic fermentation tank 6 through pipelines; the second anaerobic fermentation cold water outlet 601 and the first anaerobic fermentation cold water outlet 501 are connected to the heat storage tank cold water inlet 404 through a pipeline; the heat storage tank cold water outlet 402 is connected to the first cold water inlet 101, the second cold water inlet 201, and the third cold water inlet 301 through pipelines respectively, realizing the recycling of cold water in the anaerobic fermentation tank;

[0039] The first biogas discharge port 502 and the second biogas discharge port 602 are connected to the biogas inlet 2201 at the upper part of the flare incineration device 22 through a pipeline, and a first stop valve 19 is arranged on the connected pipeline; the first day biogas outlet 504 and the second biogas outlet 604 are connected to the biogas inlet 1001 of the purification device 10 through a pipeline, and sequentially enter the dehydration device 7, the desulfurization device 8, and the decarburization device 9. The carbon dioxide separated in the decarburization device 9 is discharged through the carbon dioxide outlet 1004 and enters the carbon dioxide liquefaction system 18 through a pipeline from the carbon dioxide inlet 1801; the natural gas separated in the decarburization device 9 is discharged through the natural gas outlet 1005 of the purification device and enters the gas compression device 14 from the natural gas inlet 1401 of the compression device through a pipeline; the compressor 12 in the gas compression device 14 compresses the natural gas, and then the natural gas outlet 1404 of the compression device discharges. And through the natural gas discharge port 1403 of the compression device, after passing through the second stop valve 20 and the pressure regulating valve 21 through a pipeline, it enters the natural gas inlet 2202 at the bottom of the flare incineration device 22; among them, the fifth stop valve 11, the compressor 12, and the sixth stop valve 13 are sequentially arranged in the gas compression device 14; carbon dioxide enters the carbon dioxide liquefaction system 18, is compressed by the compressor 12 after passing through the fourth stop valve 17, and the obtained liquid carbon dioxide is discharged through the liquid carbon dioxide outlet 1802 after passing through the third stop valve 16;

[0040] The waste heat outlets 1402 of the compression device and 1003 of the purification device are respectively connected to the second anaerobic fermentation hot water inlet 603 and the first anaerobic fermentation hot water inlet 503 through pipelines; the waste heat is recovered through a heat exchanger and used for heating the anaerobic fermentation tank, achieving efficient utilization of energy.

[0041] When the system in the above embodiment is in use, it specifically includes the following steps:

[0042] The pretreated raw materials enter the first anaerobic fermentation tank 5 and the second anaerobic fermentation tank 6, and the raw materials stay for 30 - 40 days, during which biochemical reactions occur to produce biogas.

[0043] During the biochemical reaction process, the heat generated by the first solar collector 1, the second solar collector 2, and the third solar collector 3 at the tops of the first anaerobic fermentation tank 5 and the second anaerobic fermentation tank 6 passes through the heat outlet 302 and enters the heat storage tank 4 through the heat storage tank hot water inlet 401; in order to maintain the optimal temperature of the reaction strains, the first anaerobic fermentation tank 5 and the second anaerobic fermentation tank 6 automatically draw heat from the heat storage tank 4, and the heat passes through the heat storage tank hot water outlet 403 and enters the first anaerobic fermentation tank 5 through the first anaerobic fermentation hot water inlet 503 and enters the second anaerobic fermentation tank 6 through the second anaerobic fermentation hot water inlet 603 respectively.

[0044] In order to ensure the fermentation heat demand of the first anaerobic fermentation tank 5 and the second anaerobic fermentation tank 6 under the condition of insufficient photovoltaic resources, the waste heat of the purification device 10 passes through the purification device waste heat outlet 1003 and enters the first anaerobic fermentation tank 5 through the first anaerobic fermentation hot water inlet 503 and enters the second anaerobic fermentation tank 6 through the second anaerobic fermentation hot water inlet 603 respectively.

[0045] In order to ensure the fermentation heat demand of the first anaerobic fermentation tank 5 and the second anaerobic fermentation tank 6 under the condition of insufficient photovoltaic resources, the waste heat of the gas compression device 14 passes through the waste heat outlet 1402 of the compression device and enters the first anaerobic fermentation tank 5 through the first anaerobic fermentation hot water inlet 503 and enters the second anaerobic fermentation tank 6 through the second anaerobic fermentation hot water inlet 603 respectively.

[0046] Under normal conditions, both the first stop valve 19 and the second stop valve 20 are closed.

[0047] Accident condition 1: When the first anaerobic fermentation tank 5 and the second anaerobic fermentation tank 6 are in an accident state, the first stop valve 19 will automatically open, and the biogas will respectively pass through the first biogas relief port 502 and the second biogas relief port 602, enter the flare incineration device 22 through the pipeline and the biogas inlet 2201, and the burner starts to ignite.

[0048] Accident Condition 2: When the purification device 10 is in an accident state, the first shut-off valve 19 will automatically open, and the biogas / biomethane will pass through the biogas discharge port 1002 of the purification device, enter the flare combustion device 22 through the pipeline and the biogas inlet 2201, and the burner will start and ignite.

[0049] Accident Condition 3: When the gas compression device 14 is in an accident state, the second shut-off valve 20 will automatically open, and the biomethane will pass through the natural gas discharge port 1403 of the compression device, enter the flare combustion device 22 through the pipeline, the first shut-off valve 19, and the pressure regulating valve 21 after pressure reduction, and the burner will start and ignite.

[0050] The above content is only to illustrate the technical idea of the present invention, and the protection scope of the present invention cannot be limited thereby. Any modification made on the basis of the technical solution according to the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. An integrated anaerobic fermentation self-heating biogas production system, characterized in that, It includes a solar heat collection unit, a heat storage unit, an anaerobic fermentation unit, a post-treatment system, and a flare incineration device (22); the heat medium outlet of the solar heat collection unit is connected to the heat medium inlet of the heat storage unit; the heat medium outlet of the heat storage unit is connected to the heat medium inlet of the anaerobic fermentation unit; the gas outlet of the anaerobic fermentation unit is respectively connected to the post-treatment system and the flare incineration device (22); the natural gas outlet of the post-treatment system is connected to the flare incineration device (22); the waste heat outlet of the post-treatment system is connected to the heat medium inlet of the anaerobic fermentation unit; the cold medium outlet of the anaerobic fermentation unit is connected to the cold medium inlet of the heat storage unit; the cold medium outlet of the heat storage unit is connected to the cold medium inlet of the solar heat collection unit.

2. The integrated anaerobic fermentation self-heating biogas production system according to claim 1, characterized in that, The solar heat collection unit includes a number of serially connected solar collectors; the heat storage unit is a heat storage tank (4); the anaerobic fermentation unit includes a number of serially connected anaerobic fermentation tanks; the hot water outlets of the number of solar collectors are connected and then connected to the heat medium inlet of the heat storage tank (4); the heat medium outlet of the heat storage tank (4) is connected to the heat medium inlets of the number of anaerobic fermentation tanks through a pipeline; the biogas outlets of the number of anaerobic fermentation tanks are connected to the flare incineration device (22); the natural gas outlets of the number of anaerobic fermentation tanks are connected to the post-treatment system; the heat medium outlets of the number of anaerobic fermentation tanks are connected to the cold medium inlet of the heat storage tank (4); the cold medium outlet of the heat storage tank (4) is connected to the cold medium inlet of the solar collector.

3. An integrated anaerobic fermentation self-heating biogas production system according to claim 2, characterized in that, The post-treatment system includes a purification device (10), a gas compression device (14) connected in sequence, and a carbon dioxide liquefaction system (18) connected to the purification device (10); a carbon dioxide liquefaction device (15) is arranged inside the carbon dioxide liquefaction system (18). The natural gas outlets of the number of anaerobic fermentation tanks are connected to the gas inlet of the purification device (10), the natural gas outlet (1005) of the purification device is connected to the gas inlet of the gas compression device (14), and the gas outlet of the gas compression device (14) is connected to the flare incineration device (22); the waste heat outlets of the purification device (10) and the gas compression device (14) are connected to the heat medium inlets of the number of anaerobic fermentation tanks; the carbon dioxide outlet (1004) of the purification device (10) is connected to the carbon dioxide inlet (1801) of the carbon dioxide liquefaction system (18). One end of the carbon dioxide liquefaction device (15) is connected to the carbon dioxide inlet (1801) through a fourth stop valve (17), and the other end is connected to the liquid carbon dioxide outlet (1802) of the carbon dioxide liquefaction system (18) through a third stop valve (16).

4. An integrated anaerobic fermentation self-heating biogas production system according to claim 3, characterized in that The waste heat outlets of the purification device (10) and the gas compression device (14) are connected to the heat medium inlets of the number of anaerobic fermentation tanks through a heat exchanger.

5. The integrated anaerobic fermentation and self-heating biogas production system according to claim 3, wherein, The purification device (10) includes a dehydration device (7), a desulfurization device (8), and a decarbonization device (9) connected in sequence; the gas inlet of the dehydration device (7) is connected to the natural gas outlets of several anaerobic fermentation tanks; the carbon dioxide outlet (1004) of the decarbonization device (9) is connected to the carbon dioxide inlet (1801) of the carbon dioxide liquefaction system (18); the gas outlet of the decarbonization device (9) is connected to the gas inlet of the gas compression device (14).

6. The integrated anaerobic fermentation self-heating biogas production system according to claim 5, characterized in that The gas compression device (14) includes a fifth stop valve (11), a compressor (12), and a sixth stop valve (13) connected in sequence; the fifth stop valve (11) is connected to the gas outlet of the purification device (10) through a pipeline; the sixth stop valve (13) is connected to the flare incineration device (22) through a pipeline.

7. An integrated anaerobic fermentation self-heating biogas production system according to claim 6, characterized in that The flare incineration device (22) includes a second stop valve (20), a pressure regulating valve (21), a biogas inlet (2201), and a natural gas inlet (2202); the biogas inlet (2201) and the natural gas inlet (2202) are respectively arranged at the upper and lower ends of the flare incineration device (22); the gas outlet of the gas compression device (14) is connected to the natural gas inlet (2202) through the second stop valve (20) and the pressure regulating valve (21) in sequence; the biogas outlets of the several anaerobic fermentation tanks are connected to the biogas inlet (2201).

8. An integrated anaerobic fermentation self-heating biogas production system according to claim 7, characterized in that, A first stop valve (19) is arranged on the pipeline connecting the biogas outlets of the several anaerobic fermentation tanks and the biogas inlet (2201).

9. The integrated anaerobic fermentation self-heating biogas production system according to claim 7, characterized in that, Heating coils are arranged in the anaerobic fermentation tanks.

10. A method for using the integrated anaerobic fermentation self-heating biogas production system according to any one of claims 1 to 9, characterized in that, It includes the following steps: Convert the solar energy collected by the solar heat collection unit into heat energy and store it in the heat storage unit. The heat storage unit transports the heat energy to the anaerobic fermentation unit to provide heat source for the anaerobic fermentation process. Subsequently, the gas obtained after anaerobic fermentation in the anaerobic fermentation unit is respectively transported to the flare incineration device (22) and the post-treatment system; after the post-treatment system processes the gas, natural gas and liquid carbon dioxide are obtained, and the obtained natural gas is transported to the flare incineration device (22).

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