沼气提纯技术的核心目标是高效、稳定、经济地去除杂质气体，特别是CO?和H?S，从而提升甲烷浓度。目前主流的提纯方法包括物理吸收法、化学吸收法、变压吸附法（PSA）、膜分离法以及新兴的低温分离法等。这些技术可单独使用，也可组合集成，以适应不同规模、原料和用途的项目需求。

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/有机溶剂吸收法）

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

物理吸收法利用不同气体在溶剂中的溶解度差异实现分离。其中，水洗法是应用较广的一种，其原理是：在高压条件下，CO?在水中的溶解度远高于CH?，因此将粗沼气通入水洗塔，CO?被水吸收，而甲烷则作为提纯气逸出。随后，通过减压或加热解吸，可回收CO?，实现溶剂循环利用。该方法操作简单、运行稳定，适合中等规模项目。但其缺点是能耗较高，且对H?S等酸性气体去除效果有限，通常需配合脱硫装置使用。

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.

另一种更高效的物理吸收法是使用有机溶剂（如聚乙二醇、碳酸丙烯酯等）作为吸收剂。这类溶剂对CO?的选择性吸收能力更强，再生能耗较低，甲烷回收率可达95%以上，适合大规模生物甲烷生产项目。

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、化学吸收法（胺洗法）

2、 Chemical absorption method (amine washing method)

化学吸收法主要采用胺类溶液（如MEA、DEA、MDEA等）作为吸收剂。这些胺溶液能与CO?发生可逆化学反应，生成碳酸盐或氨基甲酸盐，从而将CO?从沼气中“捕获”。提纯后的沼气中甲烷浓度可达98%以上。随后，在再生塔中通过加热使反应逆向进行，释放出高纯度CO?，同时胺溶液得以再生循环使用。

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.

胺洗法具有净化度高、适应性强的优点，尤其适用于CO?含量较高的粗沼气。但其缺点是设备投资大、能耗高（主要来自再生加热），且胺溶液易降解、产生腐蚀性副产物，需定期更换和处理。

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、变压吸附法（PSA）

3、 Pressure Swing Adsorption (PSA) method

变压吸附法是一种基于气体分子在吸附剂表面吸附能力差异的物理分离技术。常用的吸附剂包括活性炭、分子筛、硅胶等。在高压下，CO?、H?S、H?O等杂质气体比CH?更容易被吸附剂吸附，而甲烷则通过吸附床层成为产品气。当吸附剂饱和后，通过降低压力（解吸）将杂质气体脱附并排出系统，实现吸附剂再生。

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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