沼氣提純技術主要包括吸收法、變壓吸附法、低溫冷凝法和膜分離法四種方法，每種方法均基于不同的物理或化學原理實現(xiàn)二氧化碳與甲烷的高效分離。

Biogas purification technology mainly includes four methods: absorption, pressure swing adsorption, low-temperature condensation, and membrane separation. Each method is based on different physical or chemical principles to achieve efficient separation of carbon dioxide and methane.

吸收法利用有機胺溶液（如一級胺、二級胺、三級胺及空間位阻胺等）對二氧化碳的物理和化學吸收特性，在吸收塔內(nèi)通過常溫加壓條件促使胺液與沼氣中的二氧化碳發(fā)生可逆反應，從而實現(xiàn)碳捕集。隨后，富集二氧化碳的吸收液被輸送至再生塔，在加熱減壓條件下發(fā)生解吸反應，釋放出高純度二氧化碳氣體，同時再生后的貧液重新具備吸收能力并返回系統(tǒng)循環(huán)使用。該工藝通過連續(xù)的吸收-再生循環(huán)實現(xiàn)沼氣的持續(xù)脫碳凈化，具有較高的甲烷回收率，但能耗相對較高。

The absorption method utilizes the physical and chemical absorption characteristics of organic amine solutions (such as primary amines, secondary amines, tertiary amines, and steric hindrance amines) for carbon dioxide. In the absorption tower, reversible reactions between amine solutions and carbon dioxide in biogas are promoted under normal temperature and pressure conditions, thereby achieving carbon capture. Subsequently, the carbon dioxide enriched absorption solution is transported to the regeneration tower and undergoes desorption reaction under heating and pressure reduction conditions, releasing high-purity carbon dioxide gas. At the same time, the regenerated lean solution regains its absorption capacity and is returned to the system for recycling. This process achieves continuous decarbonization and purification of biogas through a continuous absorption regeneration cycle, with a high methane recovery rate but relatively high energy consumption.

變壓吸附法（PSA）則依托吸附劑（如分子篩、活性炭等）對二氧化碳的選擇性吸附能力，通過周期性壓力變化實現(xiàn)氣體分離。在高壓吸附階段，原料氣中的二氧化碳被吸附劑截留，而甲烷等弱吸附組分作為凈化氣輸出；當吸附劑趨于飽和時，系統(tǒng)通過降壓或抽真空方式促使二氧化碳脫附再生。為確保連續(xù)運行，PSA裝置通常配置兩個以上的吸附塔交替作業(yè)，通過多塔協(xié)同實現(xiàn)不間斷處理。該技術流程簡潔且適應性強，但對吸附劑性能及控制系統(tǒng)要求較高。

Pressure swing adsorption (PSA) relies on the selective adsorption ability of adsorbents (such as molecular sieves, activated carbon, etc.) for carbon dioxide, and achieves gas separation through periodic pressure changes. In the high-pressure adsorption stage, carbon dioxide in the feed gas is intercepted by the adsorbent, while weakly adsorbed components such as methane are output as purified gas; When the adsorbent approaches saturation, the system promotes the desorption and regeneration of carbon dioxide through pressure reduction or vacuum pumping. To ensure continuous operation, PSA units are usually equipped with two or more adsorption towers operating alternately, achieving uninterrupted processing through multi tower collaboration. This technology has a simple process and strong adaptability, but requires high performance of the adsorbent and control system.

低溫冷凝法基于二氧化碳與甲烷沸點的顯著差異，通過深度冷卻使二氧化碳液化析出，甲烷則作為不凝氣獲得提純。為提升能效，該工藝常采用余冷回收技術降低能耗，但其設備投資大、操作條件苛刻，尤其適用于高濃度二氧化碳沼氣體系。膜分離技術則利用不同氣體組分在膜材料中的滲透速率差異實現(xiàn)分離：二氧化碳因滲透性快于甲烷而優(yōu)先透過膜層，甲烷則作為滯留氣得到富集。工業(yè)上通常采用多級膜組串聯(lián)工藝以提高甲烷純度，該技術具有模塊化、易擴容的優(yōu)點，但膜材料成本及抗污染能力仍是制約因素。

The low-temperature condensation method is based on the significant difference in boiling points between carbon dioxide and methane. Through deep cooling, carbon dioxide is liquefied and precipitated, while methane is purified as a non condensable gas. To improve energy efficiency, this process often uses residual cooling recovery technology to reduce energy consumption, but its equipment investment is large and the operating conditions are harsh, especially suitable for high concentration carbon dioxide biogas systems. Membrane separation technology utilizes the difference in permeation rates of different gas components in membrane materials to achieve separation: carbon dioxide preferentially penetrates the membrane layer due to its faster permeability than methane, while methane is enriched as a retained gas. In industry, multi-stage membrane cascade process is commonly used to improve methane purity. This technology has the advantages of modularity and easy scalability, but the cost of membrane materials and anti pollution ability are still limiting factors.

從工程應用現(xiàn)狀來看，吸收法與變壓吸附法因技術成熟度高、經(jīng)濟性較好而占據(jù)主流，尤其適用于大中型沼氣提純項目；而低溫冷凝法與膜分離法則受限于技術復雜度或運行成本，目前應用范圍相對有限。未來隨著材料科學及工藝優(yōu)化的進步，這些技術有望在特定場景中展現(xiàn)更大潛力。

From the current status of engineering applications, absorption method and pressure swing adsorption method dominate due to their high technological maturity and good economic efficiency, especially suitable for large and medium-sized biogas purification projects; However, the low-temperature condensation method and membrane separation method are limited by technical complexity or operating costs, and their current application scope is relatively limited. In the future, with the advancement of materials science and process optimization, these technologies are expected to demonstrate greater potential in specific scenarios.

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