Biogas CO2 membrane absorption-membrane desorption system and method for carbon sequestration by coupling biomass ash and biogas slurry
Through the biogas CO2 membrane absorption-membrane desorption system coupled with biomass ash to couple carbon in biomass ash, the problems of insufficient fixed utilization of CO2, biomass ash treatment problems and difficulty in processing biomass ash treatment in biogas engineering are solved, and the negative emission of CO2 and efficient utilization of pellet fluid are achieved.
Patent Information
- Application Number
- CN202411838551.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-13
- Publication Date
- 2025-03-14
AI Technical Summary
Insufficient CO2 fixed utilization technology in existing biogas projects, resulting in direct emission of regenerated CO2; difficult biomass ash treatment problem, excessive alkalinity affects agricultural utilization; difficult treatment of biogas liquid, and high ammonia nitrogen and COD content leads to environmental pollution risks.
Biogas CO2 membrane absorption-membrane desorption system coupled with biomass ash to coerce carbon is used to achieve efficient capture and regenerate mass transfer of CO2 through a hollow fiber membrane contactor, and the biomass ash is coupled with the biomass ash to reduce the ammonia nitrogen and COD content in the pellet, while fixing CO2 in the form of carbonate precipitation.
It realizes low-cost and efficient capture of biogas CO2 and rapid desorption of absorbents, reduces the alkalinity of biomass ash, improves the fertilizer efficiency of the sterilizer, solves the problem of difficult sterilizer treatment, and achieves negative CO2 emissions, reducing the risk of environmental pollution.
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Figure CN119607812A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of biomass ash treatment in biomass power generation projects and biogas liquid treatment in biogas projects, and specifically to a biogas CO2 membrane absorption-membrane desorption system and method for coupling biomass ash with biogas liquid carbon fixation. Background Art
[0002] Biogas fermentation refers to the process in which organic waste (such as human and livestock feces, straw, weeds, etc.) is decomposed and metabolized by various microorganisms under certain moisture, temperature and anaerobic conditions to eventually form a mixed gas such as methane (CH4) and carbon dioxide (CO2). The biogas fermentation system is based on the principle of biogas fermentation, with energy production as the goal, and ultimately realizes the comprehensive utilization of biogas, biogas slurry, and biogas residue. Among them, biogas, as a clean renewable energy, can be directly used for daily household energy supply, or through cogeneration cluster power supply and heating. The CO2 generated after the use of biogas returns to the atmosphere without causing an increase in greenhouse gases. Therefore, near-zero CO2 emissions can be achieved in the process of energy utilization, which has important environmental benefits. At the same time, biogas slurry and biogas residue are also high-quality organic fertilizers, which can reduce the application of chemical fertilizers and pesticides in agricultural production applications. Therefore, biogas slurry must be reasonably treated and meet the standards to avoid environmental pollution risks. However, the characteristics of high ammonia nitrogen and high chemical oxygen demand (COD) increase the difficulty of biogas slurry treatment. Therefore, it is very necessary to explore appropriate biogas slurry treatment technology so that the biogas slurry can be efficiently treated and utilized and prevent environmental pollution.
[0003] In addition, biogas plays a very important role and position in the field of new energy utilization, and is of great significance for alleviating the greenhouse effect. The main purpose of biogas purification is to make biogas meet the biogas composition standards, remove impurities such as CO2, hydrogen sulfide, moisture, and siloxane in biogas, and convert it into biogas with a higher CH4 concentration, thereby expanding the application range of biogas. At present, the biogas purification and purification process is generally based on CO2 chemical absorption with negligible CH4 loss rate, which faces key problems such as large footprint, poor operation flexibility, and high energy consumption of absorbent regeneration. The membrane absorption biogas CO2 process successfully couples CO2 chemical absorption technology and membrane separation technology, with low cost, easy scalability and flexible operation, and can be extended to biogas projects of different scales. However, the regeneration process of biogas-rich CO2 absorbent still needs to strengthen the process mass transfer while reducing the desorption energy consumption. The membrane contactor is used as the CO2 regeneration reactor, which provides sufficient area for gas and liquid mass transfer and enhances the desorption rate of biogas-rich CO2 absorbent. By integrating the two technologies of membrane absorption and membrane desorption, efficient capture of biogas CO2 and rapid desorption of absorbent can be achieved. At present, most biogas projects do not have CO2 fixation and utilization technology due to scale issues, resulting in the direct emission of regenerated CO2 into the atmosphere. If low-cost regenerative CO2 fixation technology is introduced at the end of biogas CO2 membrane absorption-membrane desorption, it is expected to achieve negative CO2 emission production of biogas.
[0004] Biomass ash is the solid residue produced by direct combustion of biomass, and it has the characteristics of a wide range of sources. According to statistics, for every 7 billion tons of biomass burned in the world, about 480 million tons of biomass ash will be produced. Due to the limitations of treatment methods, it can only be buried on the spot or disposed of in a centralized pile, which is very likely to cause secondary pollution of the environment. How to effectively utilize biomass ash has become an environmental problem that needs to be solved urgently. Because biomass contains more alkali metal elements such as potassium, sodium, calcium, and magnesium, after direct combustion, they remain in the biomass ash in the form of oxides such as CaO, MgO, K2O, and Na2O. In addition, it is also rich in SiO2 and P2O5. Compared with fly ash, biomass ash is very similar to it in chemical reaction characteristics, and both are mainly composed of alkali metal oxides, but the heavy metal content of biomass ash is much lower than that of fly ash, and its application is safer. Biomass ash has broad application prospects in agricultural fields such as acidic soil treatment and soil fertilization. However, there are also some problems in the agricultural use of biomass ash, mainly due to the high alkalinity of biomass ash. Long-term direct application will cause the pH value of the surface soil to continue to rise, which is not conducive to soil microbial activity, surface vegetation and plant growth, and may even reduce the surface vegetation coverage. Therefore, how to reduce the alkalinity of biomass ash is a key issue in solving the application of biomass ash in the agricultural field. In addition, CaO and MgO, which are rich in biomass ash, are ideal raw materials for mineralization and carbon fixation. They can react with CO2 in solution to form calcium carbonate or magnesium carbonate precipitation, thereby permanently and safely fixing CO2 and achieving negative CO2 emissions. This reaction can proceed spontaneously, which can effectively reduce the energy consumption of carbon fixation while weakening the alkalinity of biomass ash and enhancing agricultural availability.
[0005] Based on the low-cost and efficient purification of biogas and safe treatment of biogas slurry in biogas projects, as well as a series of key issues such as low regeneration efficiency and high regeneration energy consumption of biogas-rich CO2 absorbents, effective treatment of large-scale biomass ash, and low-cost small-scale fixation of CO2, a biogas CO2 membrane absorption-membrane desorption system and method for biomass ash-coupled biogas slurry carbon fixation are provided. The advantages are: 1) integrating biogas CO2 membrane absorption and membrane desorption, strengthening CO2 capture and regeneration mass transfer, and realizing low-cost and efficient production of biogas; 2) coupling biomass ash with biogas slurry in the membrane desorption stage, which can reduce 1) Reduce the ammonia nitrogen and COD content in the biogas slurry, increase the K content in the biogas slurry, take away a large amount of biogas slurry through biomass ash, and solve the problem of difficult biogas slurry treatment; 2) At the same time, CO2 is permanently fixed in the biomass ash in the form of carbonate precipitation, which reduces the alkalinity of the biomass ash on the one hand, and achieves negative CO2 emissions on the other hand, which is more environmentally friendly; 3) When the mixed liquid after the reaction is used in agriculture, it can improve the soil layer, promote microbial activity, improve soil fertility, inhibit weed growth, reduce the occurrence of pests and diseases, and create a good soil environment for the growth and development of crops. At the same time, it can also reduce the application of fertilizers and pesticides, reduce planting costs, and improve economic benefits; 4) Waste from multiple sources is utilized as a resource, and the environmental burden is reduced. Summary of the invention
[0006] The purpose of the embodiments of the present application is to provide a biogas CO2 membrane absorption-membrane desorption system and method for biomass ash coupled with biogas slurry carbon fixation, which combines membrane absorption and membrane desorption technology to improve the biogas CO2 capture and regeneration efficiency.
[0007] To achieve the above objectives, this application provides the following technical solutions:
[0008] The embodiment of the present application provides a biogas CO2 membrane absorption-membrane desorption system for biomass ash coupled biogas slurry carbon fixation, including an anaerobic fermentation device, a biogas storage tank, a hollow fiber membrane contactor absorption system, a gas-water separation device, a CH4 gas storage bottle, a CO2 rich liquid heating device, a hollow fiber membrane contactor desorption system, a CO2 absorbent storage tank, a solid-liquid separation device, a biogas slurry storage tank, a stirring mixer, and a transportation device. It also includes a first booster fan, a second booster fan, a first liquid booster pump, a second liquid booster pump, a centrifugal pump, and a slurry pump. Among them, the anaerobic fermentation device is provided with a feed inlet, a discharge port, and a biogas outlet, and the biogas inlet of the biogas storage tank is connected to the biogas outlet of the anaerobic fermentation device. The biogas outlet of the biogas storage tank is connected to the biogas inlet of the hollow fiber membrane contactor absorption system through the first booster fan, and the biogas is purified through the shell side of the hollow fiber membrane contactor absorption system. The purified biogas outlet of the hollow fiber membrane contactor absorption system is connected to the purified biogas inlet of the gas-water separation device, and the CH4 outlet of the gas-water separation device is connected to the CH4 gas cylinder through the second booster fan. The hollow fiber membrane contactor absorption system is also provided with a CO2 lean liquid inlet and a CO2 rich liquid outlet. The CO2 lean liquid outlet of the CO2 absorbent storage tank is connected to the CO2 lean liquid inlet of the hollow fiber membrane contactor absorption system through the first liquid booster pump, and the CO2 lean liquid is purified through the pipe side of the hollow fiber membrane contactor absorption system. The CO2 rich liquid outlet of the hollow fiber membrane contactor absorption system is connected to the CO2 rich liquid inlet of the CO2 rich liquid heating device, and the CO2 rich liquid outlet of the CO2 rich liquid heating device is connected to the CO2 rich liquid inlet of the hollow fiber membrane contactor desorption system through the second liquid booster pump. The CO2 rich liquid is desorbed through the pipe side of the hollow fiber membrane contactor desorption system, and the CO2 lean liquid outlet of the hollow fiber membrane contactor desorption system is connected to the CO2 lean liquid inlet of the CO2 absorbent storage tank.
[0009] The input end of the centrifugal pump is connected to the discharge port of the anaerobic fermentation device, and the output end of the centrifugal pump is connected to the sludge inlet of the sludge storage tank through the solid-liquid separation device. The sludge outlet of the sludge storage tank is connected to the stirring mixer. The stirring mixer is also provided with a biomass ash inlet and a mixed slurry outlet. The mixed slurry outlet of the stirring mixer is connected to the mixed slurry inlet of the hollow fiber membrane contactor desorption system through a slurry pump. The mixed slurry is desorbed by CO2 rich liquid via the shell side of the hollow fiber membrane contactor desorption system. The CO2-rich mixed slurry outlet of the hollow fiber membrane contactor desorption system is connected to the input end of the transportation equipment.
[0010] In the above technical bill, the anaerobic fermentation device is provided with a stirrer and a temperature sensor for fully mixing the fermentation raw materials.
[0011] In the above technical solution, the absorption and desorption systems of the hollow fiber membrane contactor both use a PTFE hydrophobic and oleophobic membrane with a pore size of 0.1 μm.
[0012] In the above technical solution, the CO2 absorbent used can be various liquid absorbents such as monoethanolamine, diethanolamine, sterically hindered amines, ammonia water and sodium hydroxide aqueous solution.
[0013] In the above technical solution, the CO2 rich liquid heating device is provided with a paddle stirrer and a corrosion-resistant temperature sensor.
[0014] In the above technical solution, the centrifugal pump adopts a centrifugal pump with high tolerance to suspended matter.
[0015] In the above technical solution, the solid-liquid separation device is provided with a filter screen for separating the biogas slurry and biogas residue.
[0016] In the above technical solution, a stirring device for fully mixing the materials is arranged in the stirring mixer.
[0017] In the above technical solution, the anaerobic fermentation device, stirring mixer, first booster fan, second booster fan, first liquid booster pump, second liquid booster pump, centrifugal pump and slurry pump are all made of alkali-resistant and corrosion-resistant materials.
[0018] A biogas CO2 membrane absorption-membrane desorption method for coupling biogas ash with biogas liquid carbon fixation comprises the following steps:
[0019] Step 1: Organic residues such as crop residues, livestock and poultry manure, and urban solid waste enter the anaerobic fermentation device. Under the action of various microorganisms, various complex organic matter in the fermentation raw materials are decomposed to produce biogas. The produced biogas is discharged into the biogas storage tank through the biogas outlet of the anaerobic fermentation device, and the biogas slurry and biogas residue produced after fermentation are discharged through the discharge port of the anaerobic fermentation;
[0020] Step 2: The discharged biogas slurry and biogas residue are pumped into a solid-liquid separation device by a centrifugal pump for solid-liquid separation. The separated biogas residue can be used as agricultural compost, while the biogas slurry is stored in a biogas slurry storage tank for subsequent use.
[0021] Step 3: The CO2 lean liquid in the CO2 absorbent storage tank is pumped into the tube side of the hollow fiber membrane contactor absorption system through the first liquid booster pump, and the biogas in the biogas storage tank is passed into the shell side of the hollow fiber membrane contactor absorption system under the action of the first booster fan. The CO2 lean liquid and the biogas are contacted and reacted in two phases in countercurrent flow to achieve CO2 removal from the biogas. The purified biogas enters the gas-water separation device, where water vapor is removed, and then the high-concentration CH4 is pumped into the CH4 gas storage bottle for storage through the second booster fan for subsequent use;
[0022] Step 4: The biogas slurry in the biogas slurry storage tank flows into the stirring mixer, and the biomass ash waste residue enters through the biomass ash inlet of the stirring mixer. The stirring device in the stirring mixer is turned on to fully mix the biogas slurry and biomass ash. The biomass ash-biogas slurry mixed slurry is pumped into the shell side of the hollow fiber membrane contactor desorption system through the slurry pump. The CO2 rich liquid flowing out of the hollow fiber membrane contactor absorption system enters the CO2 rich liquid heating device and is heated to 70-80°C. It is then pumped into the pipe side of the hollow fiber membrane contactor desorption system through the second liquid booster pump. The CO2 desorbed from the CO2 rich liquid is fixed by the biomass ash-biogas slurry mixed slurry across the membrane under the joint drive of temperature difference and concentration difference, forming a stable carbonate precipitate, thereby realizing the permanent fixation of biogas CO2;
[0023] Step 5: The alkalinity of the biomass ash-biogas slurry mixture is greatly reduced due to the action of CO2, and can be directly transported to farmland for agricultural application through the transportation equipment 12;
[0024] Step 6: The mixed slurry is transported into the farmland, and then the soil is plowed. Through the mixing effect between the mixed slurry and the soil, the soil layer is improved, the soil fertility is increased, and it is beneficial to the growth of crops.
[0025] Compared with the prior art, the present invention has the following beneficial effects:
[0026] 1. The present invention integrates membrane absorption-membrane desorption into the biogas purification process, which occupies a small area, has low process cost and high operational flexibility. At the same time, the mass transfer efficiency is improved as a whole, and high-purity biogas can be obtained, which is conducive to broadening the subsequent utilization of biogas.
[0027] 2. The present invention uses a hollow fiber membrane contactor as a carrier, and utilizes biomass ash-liquid to desorb the CO2-rich liquid after biogas purification. The CO2 separated from the biogas reacts with the calcium and magnesium ions in the biomass ash in the solution to generate calcium carbonate and magnesium carbonate precipitation, which can permanently fix CO2, thereby achieving negative CO2 emissions.
[0028] 3. After the biogas slurry and biomass ash are fully mixed, the ammonia nitrogen and COD contents in the biogas slurry can be greatly reduced, and more alkali metal ions can be incorporated, which is beneficial to the separation and fixation of CO2 in the rich liquid, and at the same time, the fertilizer effect of the biogas slurry is enhanced, which is beneficial to agricultural production and utilization.
[0029] 4. The present invention utilizes the neutralization reaction between alkaline substances in biomass ash and biogas slurry and CO2 separated from biogas, which greatly reduces the alkalinity of biomass ash and biogas slurry, and can be directly applied to the agricultural field, avoiding the adverse effects on vegetation when they are directly applied without treatment.
[0030] 5. The present invention can process a large amount of biogas slurry in biogas projects through the absorption and adsorption of biogas slurry by biomass ash, and at the same time achieve nutrient element complementation, which is beneficial to agricultural production.
[0031] 6. The present invention can simultaneously utilize biomass ash waste to fix CO2 in biogas and treat biogas liquid, which can reduce equipment investment costs, reduce equipment footprint and increase equipment utilization.
[0032] 7. When the mixed slurry of biomass ash and biogas slurry and cultivated soil are used in agriculture according to a certain ratio, the soil layer can be improved, microbial activity can be promoted, soil fertility can be increased, weed growth can be inhibited, pests and diseases can be reduced, and a good soil environment can be created for the growth and development of crops. At the same time, the application of chemical fertilizers and pesticides can be reduced, the planting cost can be reduced, and the economic benefits can be improved. BRIEF DESCRIPTION OF THE DRAWINGS
[0033] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments of the present application will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.
[0034] Figure 1 It is a structural schematic diagram of the biogas CO2 membrane absorption-membrane desorption system and method for biomass ash coupled biogas liquid carbon fixation of the present invention.
[0035] Among them, 1 is an anaerobic fermentation device, 1.1 is a feed inlet, 1.2 is a biogas outlet, 1.3 is a discharge port, 2 is a biogas storage tank, 2.1 is a biogas inlet, 2.2 is a biogas outlet, 3 is a hollow fiber membrane contactor absorption system, 3.1 is a biogas inlet, 3.2 is a purified biogas outlet, 3.3 is a CO2 lean liquid inlet, 3.4 is a CO2 rich liquid outlet, 4 is a gas-water separation device, 4.1 is a purified biogas inlet, 4.2 is a CH4 outlet, 5 is a CH4 gas storage bottle, 5.1 is a CH4 inlet, 6 is a CO2 rich liquid heating device, 6.1 is a CO2 rich liquid inlet, 6.2 is a CO2 rich liquid outlet, 7 is a hollow fiber membrane contactor desorption system, 7.1 is a CO2 rich liquid inlet, 7.2 is a CO2 lean liquid outlet, 7.3 is a mixed slurry inlet, 7.4—mixed slurry outlet, 8—CO2 absorbent storage tank, 8.1—CO2 lean liquid inlet, 8.2—CO2 lean liquid outlet, 9—solid-liquid separation device, 9.1—slurry and sludge inlet, 9.2—sludge outlet, 9.3—slurry outlet, 10—slurry storage tank, 10.1—slurry inlet, 10.2—slurry outlet, 11—agitation mixer, 11.1—slurry inlet, 11.2—biomass ash inlet, 11.3—mixed slurry outlet, 12—transportation equipment, 12.1—CO2-rich mixed slurry inlet, 13.1—first booster fan, 13.2—first booster fan, 13.3—first liquid booster pump, 13.4—second liquid booster pump, 13.5—centrifugal pump, 13.6—ash slurry pump. DETAILED DESCRIPTION
[0036] The technical solutions in the embodiments of the present application will be described below in conjunction with the drawings in the embodiments of the present application. It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings.
[0037] The terms "comprises," "comprising," or any other variation thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the process, method, article, or apparatus that includes the element.
[0038] like Figure 1As shown, the biogas CO2 membrane absorption-membrane desorption system and method for biomass ash coupled biogas liquid carbon fixation include an anaerobic fermentation device 1, a biogas storage tank 2, a hollow fiber membrane contactor absorption system 3, a gas-water separation device 4, a CH4 gas storage bottle 5, a CO2 rich liquid heating device 6, a hollow fiber membrane contactor desorption system 7, a CO2 absorbent storage tank 8, a solid-liquid separation device 9, a biogas liquid storage tank 10, a stirring mixer 11, and a transportation device 12. It also includes a first booster fan 13.1, a second booster fan 13.2, a first liquid booster pump 13.3, a second liquid booster pump 13.4, a centrifugal pump 13.5, and a slurry pump 13.6. The anaerobic fermentation device is provided with a feed inlet 1.1, a biogas outlet 1.2, and a discharge port 1.3, and the biogas inlet 2.1 of the biogas storage tank is connected to the biogas outlet 1.2 of the anaerobic fermentation device. The biogas outlet 1.2 of the biogas storage tank is connected to the biogas inlet 3.1 of the hollow fiber membrane contactor absorption system 3 through the first booster fan 13.1, and the biogas is purified through the shell side of the hollow fiber membrane contactor absorption system 3. The purified biogas outlet 3.2 of the hollow fiber membrane contactor absorption system 3 is connected to the purified biogas inlet 4.1 of the gas-water separation device 4, and the CH4 outlet 4.2 of the gas-water separation device 4 is connected to the CH4 gas storage bottle 5 through the second booster fan 13.2. The hollow fiber membrane contactor absorption system 3 is also provided with a CO2 lean liquid inlet 3.3 and a CO2 rich liquid outlet 3.4. The CO2 lean liquid outlet 8.2 of the CO2 absorbent storage tank 8 is connected to the CO2 lean liquid inlet 3.3 of the hollow fiber membrane contactor absorption system 3 through the first liquid booster pump 13.3, and the CO2 lean liquid is purified through the pipe side of the hollow fiber membrane contactor absorption system 3. The CO2 rich liquid outlet 3.4 of the hollow fiber membrane contactor absorption system 3 is connected to the CO2 rich liquid inlet 6.1 of the CO2 rich liquid heating device 6, and the CO2 rich liquid outlet 6.2 of the CO2 rich liquid heating device 4 is connected to the CO2 rich liquid inlet 7.1 of the hollow fiber membrane contactor desorption system 7 through the liquid second liquid booster pump 13.4. The CO2 rich liquid is desorbed via the tube side of the hollow fiber membrane contactor desorption system 7, and the CO2 lean liquid outlet 7.2 of the hollow fiber membrane contactor desorption system 7 is connected to the CO2 lean liquid inlet 8.1 of the CO2 absorbent storage tank 8.The input end of the centrifugal pump 13.5 is connected to the discharge port 1.3 of the anaerobic fermentation device 1, and the output end of the centrifugal pump 13.5 is connected to the sludge inlet 10.1 of the sludge storage tank 10 through the solid-liquid separation device 9. The sludge outlet 10.2 of the sludge storage tank 10 is connected to the stirring mixer 11. The stirring mixer 11 is also provided with a biomass ash inlet 11.2 and a mixed slurry outlet 11.3. The mixed slurry outlet 11.3 of the stirring mixer is connected to the mixed slurry inlet 7.3 of the hollow fiber membrane contactor desorption system 7 through the slurry pump 13.6. The mixed slurry is desorbed by CO2 rich liquid via the shell side of the hollow fiber membrane contactor desorption system 7. The CO2 rich mixed slurry outlet 7.4 of the hollow fiber membrane contactor desorption system 7 is connected to the input end 12.1 of the transportation equipment 12.
[0039] As an embodiment, the anaerobic fermentation device 1 is provided with an agitator and a temperature sensor for fully mixing the fermentation raw materials.
[0040] As an embodiment, the hollow fiber membrane contactor absorption 3 and desorption 7 systems both use PTFE hydrophobic and oleophobic membranes with a pore size of 0.1 μm.
[0041] As an implementation mode, the CO2 absorbent used may be various liquid absorbents such as monoethanolamine, diethanolamine, sterically hindered amines, ammonia water and sodium hydroxide aqueous solution.
[0042] As an implementation mode, the CO2 rich liquid temperature increasing device 6 is provided with a paddle stirrer and a corrosion resistant temperature sensor.
[0043] As an implementation mode, the centrifugal pump 13.5 is a centrifugal pump with high suspended matter tolerance.
[0044] As an implementation mode, the solid-liquid separation device 9 is provided with a filter screen for separating the biogas slurry and biogas residue.
[0045] As an implementation mode, the stirring mixer 11 is provided with a stirring device for fully mixing the materials.
[0046] As an embodiment, the anaerobic fermentation device 1, the stirring mixer 11, the first booster fan 13.1, the second booster fan 13.2, the first liquid booster pump 13.3, the second liquid booster pump 13.4, the centrifugal pump 13.5 and the slurry pump 13.6 are all made of alkali-resistant and corrosion-resistant materials.
[0047] The specific steps of the technical solution of the present invention are as follows:
[0048] Step 1: Organic residues such as crop residues, livestock and poultry manure, and urban solid waste enter the anaerobic fermentation device 1. Under the action of various microorganisms, various complex organic substances in the fermentation raw materials are decomposed to produce biogas. The generated biogas is discharged into the biogas storage tank 2 through the biogas outlet 1.2 of the anaerobic fermentation device 1, and the biogas slurry and biogas residue produced after fermentation are discharged through the anaerobic fermentation outlet 1.3.
[0049] Step 2: The discharged biogas slurry and biogas residue are pumped into the solid-liquid separation device 9 for solid-liquid separation under the action of the centrifugal pump 13.5. The separated biogas residue can be used as agricultural compost, and the biogas slurry enters the biogas slurry storage tank 10 for storage for subsequent use.
[0050] Step 3: The CO2 lean liquid in the CO2 absorbent storage tank 8 is pumped into the tube side of the hollow fiber membrane contactor absorption system 3 by the first liquid booster pump 13.3, and the biogas in the biogas storage tank 2 is passed into the shell side of the hollow fiber membrane contactor absorption system 3 under the action of the first booster fan 13.1, and the CO2 lean liquid and the biogas are countercurrently contacted and reacted to achieve biogas CO2 removal. The purified biogas enters the gas-water separation device 4, where the water vapor is removed, and then the high-concentration CH4 is pumped into the CH4 gas storage bottle 5 for storage through the second booster fan 13.2 for subsequent use.
[0051] Step 4: The biogas slurry in the biogas slurry storage tank 10 flows into the stirring mixer 11, and the biomass ash waste enters through the biomass ash inlet 11.2 of the stirring mixer 11. The stirring device in the stirring mixer 11 is turned on to fully mix the biogas slurry and biomass ash. The biomass ash-biogas slurry mixed slurry is pumped into the shell side of the hollow fiber membrane contactor desorption system 7 through the slurry pump 13.6. The CO2 rich liquid flowing out of the hollow fiber membrane contactor absorption system 3 enters the CO2 rich liquid heating device 6 and is heated to 70-80°C, and then is pumped into the pipe side of the hollow fiber membrane contactor desorption system 7 through the second liquid booster pump 13.4. The CO2 desorbed from the CO2 rich liquid is fixed by the biomass ash-biogas slurry mixed slurry across the membrane under the joint drive of temperature difference and concentration difference, forming a stable carbonate precipitate, thereby realizing the permanent fixation of biogas CO2.
[0052] Step 5: The alkalinity of the biomass ash-biogas slurry mixture is greatly reduced due to the action of CO2, and can be directly transported to farmland for agricultural application through the transportation equipment 12.
[0053] Step 6: The mixed slurry is transported into the farmland, and then the soil is plowed. Through the mixing of the mixed slurry and the soil, the soil layer is improved, the soil fertility is improved, and it is beneficial to the growth of crops. When the soil moisture is suitable for cultivation, the mass ratio of soil to mixed slurry should be maintained at 2.6:1 or less. This ratio has a better application effect. Under this condition, the amount of mixed slurry that can be used per mu of land is about 87.5t.
[0054] In the above technical solution, step 3 can be used to remove CO2 from biogas with high efficiency and low cost to obtain high-purity biogas, which is conducive to broadening the subsequent utilization of biogas.
[0055] In the above technical scheme, through step 4, the hollow fiber membrane contactor can be used as a carrier, and the CO2-rich liquid after biogas purification is desorbed by biomass ash-biogas liquid, and the CO2 separated from the biogas reacts with the calcium and magnesium ions in the biomass ash in the solution to form calcium carbonate and magnesium carbonate precipitation, which can permanently fix CO2, thereby achieving negative CO2 emissions. In addition, the fixation of biogas CO2 greatly reduces the alkalinity of biomass ash and biogas liquid, which can be directly applied to the agricultural field, avoiding the adverse effects on vegetation when it is directly applied without treatment.
[0056] The composite membrane distillation system is provided with a first hydrophobic membrane and a second hydrophobic membrane, and three flow channels of the composite membrane distillation system from the feed side to the permeate side are realized under the action of the first hydrophobic membrane and the second hydrophobic membrane. The above description is only an embodiment of the present application and is not intended to limit the protection scope of the present application. For those skilled in the art, the present application may have various changes and variations. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.
Claims
1. A biogas CO2 membrane absorption-membrane desorption system for coupling biogas slurry carbon fixation, characterized in that: The invention comprises an anaerobic fermentation device (1), a biogas storage tank (2), a hollow fiber membrane contactor absorption system (3), a gas-water separation device (4), a CH4 gas storage bottle (5), a CO2 rich liquid heating device (6), a hollow fiber membrane contactor desorption system (7), a CO2 absorbent storage tank (8), a solid-liquid separation device (9), a biogas liquid storage tank (10), a stirring mixer (11), and a transportation device (12). The anaerobic fermentation device is provided with a feed inlet (1.1), a biogas outlet (1.2), and a discharge port (1.3). The biogas inlet (2.1) of the biogas storage tank is connected to the biogas outlet (1.2) of the anaerobic fermentation device. The biogas outlet (1.2) of the biogas storage tank is connected to the hollow fiber membrane contactor through a first booster fan (13.1). The hollow fiber membrane contactor absorption system (3) is connected to the biogas inlet (3.1) of the hollow fiber membrane contactor absorption system (3), and the biogas is purified via the shell side of the hollow fiber membrane contactor absorption system (3). The purified biogas outlet (3.2) of the hollow fiber membrane contactor absorption system (3) is connected to the purified biogas inlet (4.1) of the gas-water separation device (4), and the CH4 outlet (4.2) of the gas-water separation device (4) is connected to the CH4 gas storage bottle (5) through a second booster fan (13.2). The hollow fiber membrane contactor absorption system (3) is also provided with a CO2 lean liquid inlet (3.3) and a CO2 rich liquid outlet (3.4). The CO2 lean liquid outlet (8.2) of the CO2 absorbent storage tank (8) is connected to the hollow fiber through a first liquid booster pump (13.3). The CO2 lean liquid inlet (3.3) of the membrane contactor absorption system (3) is connected, and the CO2 lean liquid is purified by biogas via the tube side of the hollow fiber membrane contactor absorption system (3). The CO2 rich liquid outlet (3.4) of the hollow fiber membrane contactor absorption system (3) is connected to the CO2 rich liquid inlet (6.1) of the CO2 rich liquid heating device (6). The CO2 rich liquid outlet (6.2) of the CO2 rich liquid heating device (4) is connected to the CO2 rich liquid inlet (7.1) of the hollow fiber membrane contactor desorption system (7) via a liquid second liquid booster pump (13.4). The CO2 rich liquid is desorbed via the tube side of the hollow fiber membrane contactor desorption system (7). The CO2 lean liquid outlet (7.1) of the hollow fiber membrane contactor desorption system (7) .2) is connected to the CO2 lean liquid inlet (8.1) of the CO2 absorbent storage tank (8), the input end of the centrifugal pump (13.5) is connected to the discharge port (1.3) of the anaerobic fermentation device (1), the output end of the centrifugal pump (13.5) is connected to the biogas slurry inlet (10.1) of the biogas slurry storage tank (10) through the solid-liquid separation device (9), the biogas slurry outlet (10.2) of the biogas slurry storage tank (10) is connected to the stirring mixer (11), the stirring mixer (11) is provided with a biomass ash inlet (11.2) and a mixed slurry outlet (11.3), the mixed slurry outlet (11.3) of the stirring mixer is connected to the mixed slurry inlet (7.1) of the hollow fiber membrane contactor desorption system (7) through the slurry pump (13.6).3) The mixed slurry is desorbed into CO2-rich liquid via the shell side of the hollow fiber membrane contactor desorption system (7), and the CO2-rich mixed slurry outlet (7.4) of the hollow fiber membrane contactor desorption system (7) is connected to the input end (12.1) of the transport equipment (12).
2. The biogas CO2 membrane absorption-membrane desorption system for biomass ash coupled biogas liquid carbon fixation according to claim 1 is characterized by: The anaerobic fermentation device (1) is provided with a stirrer for fully mixing the fermentation raw materials and a temperature sensor.
3. The biogas CO2 membrane absorption-membrane desorption system for biomass ash coupled biogas liquid carbon fixation according to claim 1 is characterized by: The hollow fiber membrane contactor absorption (3) and desorption (7) systems both use PTFE hydrophobic and oleophobic membranes with a pore size of 0.1 μm.
4. The biogas CO2 membrane absorption-membrane desorption system for biomass ash coupled biogas liquid carbon fixation according to claim 1 is characterized by: The CO2 absorbent used is one or more liquid absorbents selected from monoethanolamine, diethanolamine, sterically hindered amines, ammonia water and sodium hydroxide aqueous solution.
5. The biogas CO2 membrane absorption-membrane desorption system for biomass ash coupled biogas liquid carbon fixation according to claim 1 is characterized by: The CO2 rich liquid temperature increasing device (6) is provided with a paddle stirrer and a corrosion resistant temperature sensor.
6. The biogas CO2 membrane absorption-membrane desorption system for biomass ash coupled biogas liquid carbon fixation according to claim 1, characterized in that: The centrifugal pump (13.5) is a centrifugal pump with high suspended matter tolerance.
7. The biogas CO2 membrane absorption-membrane desorption system for biomass ash coupled biogas liquid carbon fixation according to claim 1 is characterized by: The solid-liquid separation device (9) is provided with a filter screen for separating biogas slurry and biogas residue.
8. The biogas CO2 membrane absorption-membrane desorption system for biomass ash coupled biogas liquid carbon fixation according to claim 1, characterized in that: The stirring mixer (11) is provided with a stirring device for fully mixing the materials.
9. The biogas CO2 membrane absorption-membrane desorption system for coupling biogas ash with biogas liquid carbon fixation according to claim 1, characterized in that: The anaerobic fermentation device (1), the stirring mixer (11), the first booster fan (13.1), the second booster fan (13.2), the first liquid booster pump (13.3), the second liquid booster pump (13.4), the centrifugal pump (13.5) and the mortar pump (13.6) are all made of alkali-resistant and corrosion-resistant materials.
10. A biogas CO2 membrane absorption-membrane desorption method for coupling biogas ash with biogas liquid carbon fixation, characterized in that: The following steps are involved: Step 1: organic residues such as crop residues, livestock and poultry feces, and urban solid waste enter the anaerobic fermentation device (1). Under the action of various microorganisms, various complex organic substances in the fermentation raw materials are decomposed to produce biogas. The produced biogas is discharged through the biogas outlet (1.2) of the anaerobic fermentation device (1) into the biogas storage tank (2). The biogas slurry and biogas residue produced after fermentation are discharged through the anaerobic fermentation discharge port (1.3); Step 2: The discharged biogas slurry and biogas residue are pumped into a solid-liquid separation device (9) by a centrifugal pump (13.5) for solid-liquid separation. The biogas residue after separation can be used as agricultural compost, while the biogas slurry enters a biogas slurry storage tank (10) for storage for subsequent use; Step 3: The CO2 lean liquid in the CO2 absorbent storage tank (8) is pumped into the tube side of the hollow fiber membrane contactor absorption system (3) through the first liquid booster pump (13.3), and the biogas in the biogas storage tank (2) is passed into the shell side of the hollow fiber membrane contactor absorption system (3) under the action of the first booster fan (13.1), and the CO2 lean liquid and the biogas are contacted and reacted in two phases in countercurrent flow to achieve CO2 removal from the biogas. The purified biogas enters the gas-water separation device (4), and the water vapor therein is removed in the gas-water separation device (4), and then the high-concentration CH4 is pumped into the CH4 gas storage bottle (5) for storage through the second booster fan (13.2) for subsequent use; Step 4: The biogas slurry in the biogas slurry storage tank (10) flows into the stirring mixer (11), and the biomass ash waste residue enters through the biomass ash inlet (11.2) of the stirring mixer (11). The stirring device in the stirring mixer (11) is turned on to fully mix the biogas slurry and the biomass ash. The biomass ash-biogas slurry mixed slurry is pumped into the shell side of the hollow fiber membrane contactor desorption system (7) through the slurry pump (13.6). The CO2 rich liquid flowing out of the hollow fiber membrane contactor absorption system (3) enters the CO2 rich liquid heating device (6) and is heated to 70-80°C. It is then pumped into the tube side of the hollow fiber membrane contactor desorption system (7) through the second liquid booster pump (13.4). The CO2 desorbed from the CO2 rich liquid is fixed by the biomass ash-biogas slurry mixed slurry across the membrane under the joint drive of temperature difference and concentration difference, forming a stable carbonate precipitate, thereby achieving permanent fixation of biogas CO2; Step 5: The alkalinity of the biomass ash-biogas slurry mixture is greatly reduced due to the action of CO2, and can be directly transported to farmland for agricultural application through the transportation equipment 12; Step 6: The mixed slurry is transported into the farmland, and then the soil is plowed. Through the mixing effect between the mixed slurry and the soil, the soil layer is improved, the soil fertility is increased, and it is beneficial to the growth of crops.