沼氣提純是生物質(zhì)能源利用的關(guān)鍵環(huán)節(jié)，其核心在于去除甲烷中的二氧化碳、硫化氫等雜質(zhì)，提升燃氣熱值至天然氣標(biāo)準(zhǔn)。當(dāng)前主流技術(shù)包括變壓吸附法、化學(xué)吸收法與壓力水洗法，三者技術(shù)路徑各異，適用場景互補。

　　Biogas purification is a key link in the utilization of biomass energy, with the core being the removal of impurities such as carbon dioxide and hydrogen sulfide from methane, and the improvement of gas calorific value to natural gas standards. The current mainstream technologies include pressure swing adsorption, chemical absorption, and pressure water washing, which have different technical paths and complementary application scenarios.

　　變壓吸附法以分子篩或活性炭為吸附劑，利用氣體組分在吸附劑表面吸附力的差異實現(xiàn)分離。在高壓條件下，二氧化碳、硫化氫等強極性分子被優(yōu)先吸附，甲烷則穿透床層；降壓后吸附劑再生，雜質(zhì)氣體解吸排出。該技術(shù)優(yōu)勢顯著：吸附周期短，單周期處理量可達每小時數(shù)千立方米；模塊化設(shè)計便于擴容，尤其適合中小型沼氣工程。然而，吸附劑需定期更換或熱再生，運營成本占比較高。

　　The pressure swing adsorption method uses molecular sieves or activated carbon as adsorbents, and utilizes the difference in adsorption force of gas components on the surface of the adsorbent to achieve separation. Under high pressure conditions, strongly polar molecules such as carbon dioxide and hydrogen sulfide are preferentially adsorbed, while methane penetrates the bed; After depressurization, the adsorbent regenerates and impurities are desorbed and discharged. This technology has significant advantages: the adsorption cycle is short, and the single cycle processing capacity can reach thousands of cubic meters per hour; Modular design facilitates expansion, especially suitable for small and medium-sized biogas projects. However, adsorbents require regular replacement or thermal regeneration, which accounts for a relatively high operating cost.

　　化學(xué)吸收法通過堿性溶液與酸性氣體反應(yīng)實現(xiàn)提純。以乙醇胺溶液為例，其在吸收塔內(nèi)與沼氣逆流接觸，選擇性吸收二氧化碳和硫化氫；富液進入再生塔加熱解吸，釋放的酸性氣體可回收制硫磺或碳酸鹽。該技術(shù)凈化度高，可將甲烷純度提升至98%以上，且能同步脫除硫化物，滿足車用燃料標(biāo)準(zhǔn)。但溶劑再生需消耗蒸汽，能耗占運行成本的30%-40%，且溶液降解產(chǎn)生的熱穩(wěn)定性鹽需定期處理。

　　Chemical absorption method achieves purification by reacting alkaline solution with acidic gas. Taking ethanolamine solution as an example, it selectively absorbs carbon dioxide and hydrogen sulfide by countercurrent contact with biogas in the absorption tower; The rich solution enters the regeneration tower for heating and desorption, and the released acidic gas can be recovered to produce sulfur or carbonate. This technology has a high degree of purification, which can increase the purity of methane to over 98%, and can simultaneously remove sulfides, meeting the standards for automotive fuels. However, solvent regeneration requires steam consumption, which accounts for 30% -40% of operating costs, and the thermally stable salts generated by solution degradation need to be treated regularly.

　　壓力水洗法利用氣體溶解度差異進行分離。在加壓條件下，沼氣與循環(huán)水在填料塔內(nèi)充分接觸，二氧化碳因溶解度高被水吸收，甲烷則從塔頂逸出。富液經(jīng)減壓閃蒸釋放二氧化碳，部分水汽冷凝回流，實現(xiàn)溶液循環(huán)。該技術(shù)設(shè)備簡單、投資成本低，尤其適用于含水量高的沼氣原料。但水洗過程需處理大量含雜質(zhì)廢水，且壓力波動易導(dǎo)致甲烷溶解損失，實際運行中需嚴格控制操作壓力在0.8-1.2MPa范圍內(nèi)。

　　The pressure water washing method utilizes the difference in gas solubility for separation. Under pressurized conditions, biogas and circulating water come into full contact within the packed tower. Carbon dioxide is absorbed by water due to its high solubility, while methane escapes from the top of the tower. The rich solution releases carbon dioxide through vacuum flash evaporation, and some water vapor condenses and refluxes to achieve solution circulation. This technology has simple equipment and low investment cost, especially suitable for biogas raw materials with high moisture content. However, the water washing process requires the treatment of a large amount of wastewater containing impurities, and pressure fluctuations can easily lead to methane dissolution losses. In actual operation, it is necessary to strictly control the operating pressure within the range of 0.8-1.2MPa.

　　技術(shù)選型需綜合考量原料特性、產(chǎn)品用途及經(jīng)濟性。對于餐廚垃圾沼氣，因含硫量較高，化學(xué)吸收法可實現(xiàn)脫硫提純一體化；在養(yǎng)殖場沼氣工程中，變壓吸附法憑借其靈活性和低維護需求占據(jù)主流；而壓力水洗法因抗雜質(zhì)沖擊能力強，常被用于預(yù)處理階段。隨著膜分離、低溫冷凝等新興技術(shù)的發(fā)展，沼氣提純正朝著高效化、集成化方向演進，為生物天然氣產(chǎn)業(yè)化提供技術(shù)支撐。

　　The selection of technology should comprehensively consider the characteristics of raw materials, product use, and economy. For kitchen waste biogas, due to its high sulfur content, chemical absorption method can achieve integrated desulfurization and purification; In biogas engineering in breeding farms, pressure swing adsorption method dominates due to its flexibility and low maintenance requirements; The pressure water washing method is often used in the pretreatment stage due to its strong resistance to impurity impact. With the development of emerging technologies such as membrane separation and low-temperature condensation, biogas purification is evolving towards high efficiency and integration, providing technical support for the industrialization of biogas.

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