沼氣通常含有55%左右的甲烷和45%左右的二氧化碳，此外還有少量的硫化氫等雜質(zhì)氣體。這種低熱值的氣體直接利用效率有限，而通過提純將甲烷濃度提升至97%以上，即可獲得與天然氣品質(zhì)相當(dāng)?shù)纳锾烊粴狻Ｕ託馓峒?，正是實現(xiàn)這一轉(zhuǎn)變的核心技術(shù)環(huán)節(jié)。

Biogas usually contains about 55% methane and 45% carbon dioxide, as well as a small amount of impurities such as hydrogen sulfide. The direct utilization efficiency of this low calorific value gas is limited, and by purifying it, the methane concentration can be increased to over 97% to obtain bio natural gas of comparable quality to natural gas. Biogas purification is the core technical link to achieve this transformation.

沼氣提純的主流技術(shù)主要包括吸收法、變壓吸附法（PSA）和膜分離法三大類。

The mainstream technologies for biogas purification mainly include absorption, pressure swing adsorption (PSA), and membrane separation.

吸收法是非常早應(yīng)用也是目前較為成熟的提純技術(shù)，具體又可分為物理吸收和化學(xué)吸收兩種路徑。壓力水洗技術(shù)是物理吸收的典型代表，其原理是利用CO?與CH?在水中溶解度的顯著差異——在加壓條件下，CO?被水選擇性吸收，從而實現(xiàn)甲烷的富集。吸收水經(jīng)減壓解析后可再生循環(huán)使用。該技術(shù)的甲烷回收率可達(dá)98.5%以上，且可在40%至120%的負(fù)荷區(qū)間內(nèi)穩(wěn)定運(yùn)行。化學(xué)吸收法則采用有機(jī)胺溶液（一級胺、二級胺、三級胺等）與二氧化碳發(fā)生化學(xué)反應(yīng)來實現(xiàn)分離。醇胺法是化學(xué)吸收中非常常用的工藝之一，在浙江某沼氣凈化提純生物天然氣項目中便采用了這一工藝路線。

Absorption method is the earliest and currently mature purification technology, which can be divided into two paths: physical absorption and chemical absorption. Pressure water washing technology is a typical representative of physical absorption, which utilizes the significant difference in solubility between CO? And CH? In water - under pressurized conditions, CO? Is selectively absorbed by water, thereby achieving efficient enrichment of methane. After absorbing water and undergoing depressurization analysis, it can be recycled and reused. The methane recovery rate of this technology can reach over 98.5%, and it can operate stably within the load range of 40% to 120%. The chemical absorption method uses organic amine solutions (primary amines, secondary amines, tertiary amines, etc.) to undergo chemical reactions with carbon dioxide to achieve separation. The alcohol amine method is one of the most commonly used processes in chemical absorption, and this process route was adopted in a biogas purification and bio natural gas project in Zhejiang.

變壓吸附法（PSA） 是利用不同氣體分子在不同壓力下對吸附劑親和性的差異來實現(xiàn)氣體分離。常用的吸附劑包括活性炭、分子篩等。沼氣經(jīng)分液罐除去水分，再經(jīng)脫硫塔脫硫后，進(jìn)入PSA系統(tǒng)提純得到產(chǎn)品天然氣。近年來，采用“旋轉(zhuǎn)閥PSA+抽真空”的VPSA工藝路線，結(jié)合新型旋轉(zhuǎn)閥和高性能吸附劑，實現(xiàn)了快速動態(tài)吸附和提純。PSA法操作靈活、自動化程度高，適合中小規(guī)模的沼氣提純項目。

Pressure swing adsorption (PSA) is a gas separation method that utilizes the differences in affinity of different gas molecules for adsorbents at different pressures. Common adsorbents include activated carbon, molecular sieves, etc. Biogas is separated from water by a separation tank, and then desulfurized by a desulfurization tower before entering the PSA system for purification to obtain natural gas products. In recent years, the VPSA process route of "rotary valve PSA+vacuum pumping" has been adopted, combined with new rotary valves and high-performance adsorbents, to achieve rapid dynamic adsorption and efficient purification. The PSA method is flexible in operation and highly automated, suitable for small and medium-sized biogas purification projects.

膜分離法是基于不同氣體分子通過膜材料的滲透速率差異實現(xiàn)分離。通過合理設(shè)計膜組件的排列方式和優(yōu)化操作條件（如壓力、溫度、流速等），可以不斷提高沼氣提純的效率和純度。膜分離法設(shè)備緊湊、能耗較低，但膜材料的性能和壽命是影響其經(jīng)濟(jì)性的關(guān)鍵因素。

Membrane separation method is based on the difference in permeation rate of different gas molecules through membrane materials to achieve separation. By reasonably designing the arrangement of membrane components and optimizing operating conditions (such as pressure, temperature, flow rate, etc.), the efficiency and purity of biogas purification can be continuously improved. The membrane separation method has compact equipment and low energy consumption, but the performance and lifespan of membrane materials are key factors affecting its economy.

此外，低溫冷凝法也是一種可選的提純技術(shù)，但由于經(jīng)濟(jì)性因素，在實際應(yīng)用中相對較少。

In addition, low-temperature condensation is also an optional purification technology, but due to economic factors, it is relatively rare in practical applications.

沼氣提純的完整工藝流程通常包含脫硫、脫水、除二氧化碳及壓縮等多個環(huán)節(jié)。在實際工程中，多種技術(shù)也常常組合使用。例如，青島能源所開發(fā)的沼氣提純技術(shù)與撬裝裝備，采用絡(luò)合鐵脫硫技術(shù)進(jìn)行脫硫（H?S脫除率可達(dá)99%以上），再以壓力水洗技術(shù)進(jìn)行脫碳，整套裝備已成功推廣了十余處千萬方級生物天然氣工程項目。

The complete process of biogas purification usually includes multiple steps such as desulfurization, dehydration, carbon dioxide removal, and compression. In practical engineering, multiple technologies are often used in combination. For example, the biogas purification technology and equipment developed by Qingdao Energy Institute use complex iron desulfurization technology for desulfurization (with a H2S removal rate of over 99%), and then use pressure water washing technology for decarbonization. The entire equipment has successfully promoted more than ten million cubic meters of bio natural gas engineering projects.

從產(chǎn)業(yè)發(fā)展的角度來看，沼氣提純生產(chǎn)的生物天然氣不僅能替代傳統(tǒng)化石能源，更有助于推動能源結(jié)構(gòu)向清潔、低碳方向平穩(wěn)過渡。近年來，我國在生物天然氣的標(biāo)準(zhǔn)化建設(shè)方面也取得了重要進(jìn)展——GB/T 41328《生物天然氣》等標(biāo)準(zhǔn)的出臺，填補(bǔ)了全球生物天然氣標(biāo)準(zhǔn)領(lǐng)域的空白，為生物天然氣的產(chǎn)品貿(mào)易交割和行業(yè)安全管理提供了依據(jù)。隨著技術(shù)持續(xù)進(jìn)步和政策不斷完善，沼氣提純產(chǎn)業(yè)正迎來前所未有的發(fā)展機(jī)遇，有望在可再生能源體系中扮演更加重要的角色。

From the perspective of industrial development, the bio natural gas produced by biogas purification can not only replace traditional fossil fuels, but also help promote a smooth transition of energy structure towards a clean and low-carbon direction. In recent years, China has also made significant progress in the standardization construction of biogas - the introduction of standards such as GB/T 41328 "Bionatural Gas" has filled the gap in the global biogas standard field, providing a basis for the trade and delivery of biogas products and industry safety management. With continuous technological advancement and policy improvement, the biogas purification industry is facing unprecedented development opportunities and is expected to play a more important role in the renewable energy system.