沼氣作為生物質能轉化產物，主要成分為甲烷（50%-70%）和二氧化碳，并含有硫化氫、水分等雜質。通過提純工藝去除雜質并提高甲烷濃度，可使其達到天然氣標準，實現能源的高值化利用。當前主流提純技術涵蓋物理、化學及生物方法，工藝選擇需綜合考量原料特性、處理規模及產品用途。

　　Biogas, as a product of biomass energy conversion, is mainly composed of methane (50% -70%) and carbon dioxide, and contains impurities such as hydrogen sulfide and moisture. By using purification processes to remove impurities and increase methane concentration, it can meet natural gas standards and achieve high-value energy utilization. The current mainstream purification technologies cover physical, chemical, and biological methods, and the process selection needs to comprehensively consider the characteristics of raw materials, processing scale, and product use.

　　預處理：雜質去除與氣質穩定

　　Preprocessing: Impurity removal and gas stability

　　沼氣提純前需進行預處理，以保護后續設備并提升提純效率。首先通過旋風分離器去除顆粒物，再利用氣液分離罐脫除冷凝水。對于高含硫沼氣，需設置堿液洗滌塔脫除硫化氫，某垃圾填埋場案例顯示，堿洗后硫化氫濃度可從5000ppm降至20ppm以下。預處理階段還需通過加熱器維持沼氣溫度在40-50℃，避免低溫導致的組分冷凝。

　　Pre treatment is required before biogas purification to protect subsequent equipment and improve purification efficiency. Firstly, remove particulate matter through a cyclone separator, and then use a gas-liquid separation tank to remove condensed water. For high sulfur biogas, it is necessary to set up an alkaline washing tower to remove hydrogen sulfide. A case study of a landfill site shows that the concentration of hydrogen sulfide can be reduced from 5000ppm to below 20ppm after alkaline washing. During the pre-treatment stage, it is necessary to maintain the biogas temperature at 40-50 ℃ through a heater to avoid component condensation caused by low temperatures.

　　脫硫工藝：化學吸收與生物法協同

　　Desulfurization process: chemical absorption and biological method synergy

　　硫化氫是沼氣提純的關鍵控制指標，其去除方法包括：

　　Hydrogen sulfide is a key control indicator for biogas purification, and its removal methods include:

　　化學吸收法：采用氫氧化鈉或三嗪類溶液吸收硫化氫，某養殖場沼氣工程應用表明，該技術脫硫效率可達99%，但需定期處理廢液。

　　Chemical absorption method: Sodium hydroxide or triazine solution is used to absorb hydrogen sulfide. The application of this technology in a biogas project in a certain breeding farm shows that the desulfurization efficiency can reach 99%, but the waste liquid needs to be treated regularly.

　　生物脫硫法：利用硫桿菌將硫化氫氧化為單質硫，具有無二次污染優勢。某污水處理廠實踐數據顯示，生物脫硫系統運行成本較化學法降低40%，但啟動周期較長。

　　Biological desulfurization method: using sulfur bacteria to oxidize hydrogen sulfide into elemental sulfur, which has the advantage of no secondary pollution. Practical data from a certain sewage treatment plant shows that the operating cost of a biological desulfurization system is reduced by 40% compared to chemical methods, but the start-up cycle is longer.

　　干法脫硫：通過氧化鐵或活性炭吸附硫化氫，適合小型沼氣工程，某食品加工廠案例顯示，填料更換周期與沼氣含硫量呈負相關。

　　Dry desulfurization: It uses iron oxide or activated carbon to adsorb hydrogen sulfide, which is suitable for small-scale biogas projects. A case study of a food processing plant shows that the replacement cycle of fillers is negatively correlated with the sulfur content of biogas.

　　脫水技術：冷凝與吸附雙模式

　　Dehydration technology: dual mode of condensation and adsorption

　　沼氣脫水主要采用：

　　Biogas dehydration mainly adopts:

　　冷卻脫水法：通過換熱器將沼氣溫度降至5℃以下，使水分冷凝析出。某餐廚垃圾處理項目應用表明，該技術可去除80%的水分，但需配套制冷機組。

　　Cooling dehydration method: By using a heat exchanger to lower the temperature of biogas to below 5 ℃, the water is condensed and precipitated. The application of a certain kitchen waste treatment project shows that this technology can remove 80% of moisture, but it requires a supporting refrigeration unit.

　　吸附脫水法：采用分子篩或硅膠吸附水分，某農業廢棄物沼氣工程數據顯示，吸附法使沼氣露點降至-60℃，滿足長輸管道要求。

　　Adsorption dehydration method: Molecular sieves or silica gel are used to adsorb water. Data from an agricultural waste biogas project shows that the adsorption method reduces the dew point of biogas to -60 ℃, meeting the requirements of long-distance pipelines.

　　膜分離脫水：利用高分子膜的選擇性滲透實現氣水分離，具有無相變、能耗低特點，但膜材料耐污性需提升。

　　Membrane Separation Dehydration: Utilizing the selective permeation of polymer membranes to achieve gas water separation, it has the characteristics of no phase change and low energy consumption, but the fouling resistance of membrane materials needs to be improved.

　　脫碳工藝：吸收、吸附與膜分離

　　Decarbonization process: absorption, adsorption, and membrane separation

　　二氧化碳去除是沼氣提純的核心環節，主流技術包括：

　　Carbon dioxide removal is the core process of biogas purification, and mainstream technologies include:

　　化學吸收法：采用胺類溶液吸收二氧化碳，某大型沼氣發電項目應用表明，該技術脫碳效率可達95%，但再生能耗占提純總能耗的60%。

　　Chemical absorption method: Amine solution is used to absorb carbon dioxide. The application of this technology in a large-scale biogas power generation project has shown that the decarbonization efficiency can reach 95%, but the regeneration energy consumption accounts for 60% of the total purification energy consumption.

　　變壓吸附法（PSA）：利用吸附劑在高壓下吸附二氧化碳，某生物天然氣項目數據顯示，PSA工藝使甲烷純度提升至97%，且可實現二氧化碳資源化利用。

　　Pressure swing adsorption (PSA) method: using adsorbents to adsorb carbon dioxide under high pressure. Data from a certain biogas project shows that the PSA process increases methane purity to 97% and can achieve the resource utilization of carbon dioxide.

　　膜分離法：通過中空纖維膜實現甲烷與二氧化碳的滲透速率差異，某德國工程案例顯示，膜分離系統能耗較吸收法降低30%，但需定期更換膜組件。

　　Membrane separation method: The difference in permeation rate between methane and carbon dioxide is achieved through hollow fiber membranes. A German engineering case showed that the energy consumption of the membrane separation system is reduced by 30% compared to the absorption method, but the membrane components need to be replaced regularly.

　　精制與壓縮：產品氣品質保障

　　Refining and Compression: Product Gas Quality Assurance

　　提純后的沼氣需進行精制處理，包括：

　　The purified biogas needs to be refined, including:

　　甲烷濃度檢測：采用紅外光譜分析儀實時監測甲烷含量，確保達到天然氣標準。

　　Methane concentration detection: Real time monitoring of methane content using an infrared spectrometer to ensure compliance with natural gas standards.

　　加臭處理：按標準添加硫醇類加臭劑，某燃氣公司實踐表明，加臭后泄漏檢測靈敏度提升。

　　Odorization treatment: Adding thiol odorants according to standards, a gas company's practice has shown that the sensitivity of leak detection is improved after odorization.

　　壓縮儲存：通過多級壓縮機將沼氣增壓至20MPa，儲存于高壓氣瓶組，某車用燃料項目應用顯示，壓縮過程能耗占提純總能耗的15%。

　　Compressed storage: The biogas is pressurized to 20MPa by a multi-stage compressor and stored in a high-pressure gas cylinder group. The application of a certain automotive fuel project shows that the energy consumption of the compression process accounts for 15% of the total energy consumption of purification.

　　工藝優化方向：能效提升與資源化

　　Process optimization direction: energy efficiency improvement and resource utilization

　　熱集成技術：回收吸收塔再生熱用于沼氣預熱，某工程案例實現能耗降低。

　　Thermal integration technology: Recycling absorption tower regeneration heat for biogas preheating, achieving energy consumption reduction in a certain engineering case.

　　二氧化碳捕集利用：將提純產生的二氧化碳用于食品保鮮或驅油，某油田項目年增油量達。

　　Carbon dioxide capture and utilization: The purified carbon dioxide is used for food preservation or oil displacement, resulting in an annual increase in oil production for a certain oilfield project.

　　智能控制系統：通過物聯網平臺實時監測各環節參數，某示范工程應用后，提純效率提升。

　　Intelligent control system: Real time monitoring of parameters in various links through the Internet of Things platform. After application in a demonstration project, the purification efficiency has been improved.

　　沼氣提純工藝需構建“預處理-脫硫-脫水-脫碳-精制”的技術鏈條，通過化學吸收、膜分離等技術的組合應用，實現甲烷純度的提升。隨著碳捕集利用與封存（CCUS）技術的融合，未來沼氣提純將向“零排放、全利用、智能化”方向發展，為生物質能規模化利用提供關鍵支撐。

　　The biogas purification process requires the construction of a technical chain of "pretreatment desulfurization dehydration decarbonization refining", which can improve methane purity through the combination of chemical absorption, membrane separation and other technologies. With the integration of carbon capture, utilization, and storage (CCUS) technology, biogas purification will develop towards "zero emissions, full utilization, and intelligence" in the future, providing key support for the large-scale utilization of biomass energy.

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