沼氣提純技術的核心目標是高效、穩定、經濟地去除雜質氣體，特別是CO?和H?S，從而提升甲烷濃度。目前主流的提純方法包括物理吸收法、化學吸收法、變壓吸附法（PSA）、膜分離法以及新興的低溫分離法等。這些技術可單獨使用，也可組合集成，以適應不同規模、原料和用途的項目需求。

The core goal of biogas purification technology is to efficiently, stably, and economically remove impurity gases, especially CO and H2S, in order to increase methane concentration. The current mainstream purification methods include physical absorption, chemical absorption, pressure swing adsorption (PSA), membrane separation, and emerging low-temperature separation methods. These technologies can be used individually or combined and integrated to meet project requirements of different scales, materials, and uses.

一、物理吸收法（水洗法/有機溶劑吸收法）

1、 Physical absorption method (water washing method/organic solvent absorption method)

物理吸收法利用不同氣體在溶劑中的溶解度差異實現分離。其中，水洗法是應用較廣的一種，其原理是：在高壓條件下，CO?在水中的溶解度遠高于CH?，因此將粗沼氣通入水洗塔，CO?被水吸收，而甲烷則作為提純氣逸出。隨后，通過減壓或加熱解吸，可回收CO?，實現溶劑循環利用。該方法操作簡單、運行穩定，適合中等規模項目。但其缺點是能耗較高，且對H?S等酸性氣體去除效果有限，通常需配合脫硫裝置使用。

The physical absorption method utilizes the difference in solubility of different gases in solvents to achieve separation. Among them, the water washing method is a widely used one, and its principle is that under high pressure conditions, the solubility of CO? In water is much higher than that of CH?, so crude biogas is passed into the water washing tower, and CO? Is absorbed by water, while methane is released as purified gas. Subsequently, CO? Can be recovered through depressurization or heating desorption, achieving solvent recycling. This method is easy to operate, stable to run, and suitable for medium-sized projects. But its disadvantages are high energy consumption and limited removal effect on acidic gases such as H2S, which usually requires the use of desulfurization equipment.

另一種更高效的物理吸收法是使用有機溶劑（如聚乙二醇、碳酸丙烯酯等）作為吸收劑。這類溶劑對CO?的選擇性吸收能力更強，再生能耗較低，甲烷回收率可達95%以上，適合大規模生物甲烷生產項目。

Another more efficient physical absorption method is to use organic solvents (such as polyethylene glycol, propylene carbonate, etc.) as absorbents. This type of solvent has stronger selective absorption ability for CO?, lower regeneration energy consumption, and a methane recovery rate of over 95%, making it suitable for large-scale biomethane production projects.

二、化學吸收法（胺洗法）

2、 Chemical absorption method (amine washing method)

化學吸收法主要采用胺類溶液（如MEA、DEA、MDEA等）作為吸收劑。這些胺溶液能與CO?發生可逆化學反應，生成碳酸鹽或氨基甲酸鹽，從而將CO?從沼氣中“捕獲”。提純后的沼氣中甲烷濃度可達98%以上。隨后，在再生塔中通過加熱使反應逆向進行，釋放出高純度CO?，同時胺溶液得以再生循環使用。

The chemical absorption method mainly uses amine solutions (such as MEA, DEA, MDEA, etc.) as absorbents. These amine solutions can undergo reversible chemical reactions with CO? To form carbonates or amino formates, thereby "capturing" CO? From biogas. The methane concentration in purified biogas can reach over 98%. Subsequently, the reaction is reversed by heating in the regeneration tower, releasing high-purity CO?, while the amine solution is regenerated and reused.

胺洗法具有凈化度高、適應性強的優點，尤其適用于CO?含量較高的粗沼氣。但其缺點是設備投資大、能耗高（主要來自再生加熱），且胺溶液易降解、產生腐蝕性副產物，需定期更換和處理。

The amine washing method has the advantages of high purification and strong adaptability, especially suitable for crude biogas with high CO? Content. But its disadvantages are high equipment investment and energy consumption (mainly from regenerative heating), and the amine solution is prone to degradation and produces corrosive by-products, which need to be replaced and treated regularly.

三、變壓吸附法（PSA）

3、 Pressure Swing Adsorption (PSA) method

變壓吸附法是一種基于氣體分子在吸附劑表面吸附能力差異的物理分離技術。常用的吸附劑包括活性炭、分子篩、硅膠等。在高壓下，CO?、H?S、H?O等雜質氣體比CH?更容易被吸附劑吸附，而甲烷則通過吸附床層成為產品氣。當吸附劑飽和后，通過降低壓力（解吸）將雜質氣體脫附并排出系統，實現吸附劑再生。

Pressure swing adsorption is a physical separation technology based on the difference in adsorption capacity of gas molecules on the surface of adsorbents. Common adsorbents include activated carbon, molecular sieves, silica gel, etc. Under high pressure, CO?、H? S、H? Impurity gases such as O are more easily adsorbed by adsorbents than CH?, while methane becomes the product gas through the adsorption bed. After the adsorbent is saturated, the impurity gas is desorbed and discharged from the system by reducing the pressure (desorption), achieving adsorbent regeneration.

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