一、 沼氣提純

1、 Biogas purification

沼氣的成分主要為甲烷（50%~60%）和二氧化碳（40%~50%），沼氣提純技術(shù)通過去除沼氣中雜質(zhì)成分，可以提高沼氣中甲烷含量和能量密度，進(jìn)而制得高品質(zhì)生物天然氣。精制后的生物天然氣通過加壓調(diào)制后可以用作汽車和火車燃料。在德國和瑞典，新建沼氣工程多配有相應(yīng)沼氣精制設(shè)備，沼氣提純技術(shù)已成為目前沼氣能源應(yīng)用方面的研究熱點(diǎn)。

The main components of biogas are methane (50%~60%) and carbon dioxide (40%~50%). Biogas purification technology can improve the methane content and energy density in biogas by removing impurities, thereby producing high-quality biogas. The refined bio natural gas can be used as fuel for cars and trains after being pressurized and modulated. In Germany and Sweden, new biogas projects are often equipped with corresponding biogas refining equipment, and biogas purification technology has become a research hotspot in the application of biogas energy.

目前工業(yè)應(yīng)用的沼氣脫碳制備生物天然氣的工藝主要有高壓水洗、物理吸收、化學(xué)吸收、變壓吸附、膜分離等。這些方法的本質(zhì)是將二氧化碳從沼氣中分離出并排放到大氣中，是一種拋棄式脫碳，這不僅造成溫室氣體排放，而且極大地浪費(fèi)了二氧化碳資源。

At present, the industrial application of biogas decarbonization to produce biogas mainly includes high-pressure water washing, physical absorption, chemical absorption, pressure swing adsorption, membrane separation, etc. The essence of these methods is to separate carbon dioxide from biogas and emit it into the atmosphere, which is a form of abandoned decarbonization. This not only causes greenhouse gas emissions, but also greatly wastes carbon dioxide resources.

如果進(jìn)行二氧化碳加氫甲烷化脫碳，則可以利用二氧化碳資源提高生物天然氣產(chǎn)量，是一種利用式脫碳。

If carbon dioxide hydrogenation methane decarbonization is carried out, carbon dioxide resources can be utilized to increase the production of biogas, which is a utilization type decarbonization.

二、 加氫提純技術(shù)分類

2、 Classification of hydrogenation purification technology

根據(jù)加氫方式的不同，沼氣提純方式可分為原位加氫提純和異位加氫提純。所謂原位加氫提純方式，是將外源氫氣直接通入真是的沼氣發(fā)酵體系中，在原位把沼氣中的CO2轉(zhuǎn)化成CH4，達(dá)到純化升級沼氣的目的，國外學(xué)者針對加氫提純技術(shù)做了一系列探索性研究：

According to different hydrogenation methods, biogas purification methods can be divided into in-situ hydrogenation purification and ex situ hydrogenation purification. The so-called in-situ hydrogenation purification method is to directly introduce external hydrogen gas into the real biogas fermentation system, convert CO2 in biogas into CH4 in situ, and achieve the purpose of purifying and upgrading biogas. Foreign scholars have conducted a series of exploratory studies on hydrogenation purification technology:

1、 原位加氫提純

1. In situ hydrogenation purification

以畜禽糞便和絮狀污泥等固體廢物的發(fā)酵體系為研究對象，實(shí)驗(yàn)證明通入外源氫氣確實(shí)可以有效地提高沼氣的生成速率和甲烷濃度，而沼氣中的二氧化碳含量由對比實(shí)驗(yàn)中的38%降至12%，初步取得了沼氣提純效果。

Taking the fermentation system of solid waste such as animal manure and flocculent sludge as the research object, experiments have shown that the introduction of exogenous hydrogen gas can effectively improve the generation rate and methane concentration of biogas. The carbon dioxide content in biogas has been reduced from 38% in the comparative experiment to 12%, and the preliminary purification effect of biogas has been achieved.

此外為了解決原位沼氣提純中pH值升高的問題，他們開展了與酸性廢物共發(fā)酵實(shí)驗(yàn)研究，把發(fā)酵體系的pH值有效地控制在8.0以下；針對氣液傳質(zhì)速率低這一難點(diǎn)，采用中空纖維膜（HFM）組件曝氣來代替?zhèn)鹘y(tǒng)微孔曝氣方式，提高了H2在發(fā)酵液界面處的氣液傳質(zhì)。

In addition, in order to solve the problem of pH increase in in-situ biogas purification, they conducted co fermentation experiments with acidic waste, effectively controlling the pH value of the fermentation system below 8.0; In response to the difficulty of low gas-liquid mass transfer rate, hollow fiber membrane (HFM) module aeration was adopted instead of traditional microporous aeration to improve the gas-liquid mass transfer of H2 at the fermentation liquid interface.

結(jié)果表明，在55℃發(fā)酵溫度和150r/min攪拌強(qiáng)度下，當(dāng)以1440mL/（L?d）的速率持續(xù)通氣時(shí)，H2會(huì)被消耗完全，CH4的濃度達(dá)到90.2%，而在不通氫的發(fā)酵體系中，產(chǎn)生的沼氣只含有55.4%的CH4，CO2的比重占44.6%。

The results showed that under a fermentation temperature of 55 ℃ and a stirring intensity of 150r/min, when continuously aerated at a rate of 1440mL/(L? D), H2 was completely consumed, and the concentration of CH4 reached 90.2%. However, in a fermentation system without hydrogen, the produced biogas only contained 55.4% CH4, and the proportion of CO2 accounted for 44.6%.

2、 異位加氫提純

2. Ectopic hydrogenation purification

異位沼氣提純實(shí)驗(yàn)中，富集有嗜氫甲烷菌的厭氧反應(yīng)器被作為單獨(dú)的沼氣提純單元，經(jīng)提純處理后，沼氣中CH4達(dá)到95%左右，成功實(shí)現(xiàn)沼氣提純。

In the experiment of heterotopic biogas purification, an anaerobic reactor enriched with hydrogen loving methane bacteria was used as a separate biogas purification unit. After purification treatment, the CH4 in biogas reached about 95%, successfully achieving biogas purification.

在氫氣來源方面，除了利用可再生電能電解水制氫外，還可用焦?fàn)t氣代替純氫氣，同步實(shí)現(xiàn)沼氣提純和焦?fàn)t氣資源化雙重目的。

In terms of hydrogen sources, in addition to using renewable electricity to electrolyze water for hydrogen production, coke oven gas can also be used instead of pure hydrogen to achieve the dual goals of biogas purification and coke oven gas resource utilization simultaneously.

三、 國內(nèi)加氫提純技術(shù)發(fā)展現(xiàn)狀

3、 Development status of domestic hydrogenation purification technology

近期，中國科學(xué)院成都生物研究所開展了高溫原位加氫甲烷化制備生物天然氣的研究，直接將氫氣通入豬糞厭氧消化反應(yīng)器內(nèi)，平均甲烷產(chǎn)率從未加氫階段的222L/kgVS提高至292L/kgVS，平均相對甲烷含量從66%提高至83%。

Recently, the Chinese Academy of Sciences Chengdu Institute of Biology has carried out the research on the preparation of biological natural gas by high-temperature in-situ hydro methanation. Hydrogen is directly introduced into the pig manure anaerobic digestion reactor, and the average methane yield has increased from 222L/kgVS in the hydrogenation stage to 292L/kgVS, and the average relative methane content has increased from 66% to 83%.

通過微生物多樣性分析表明，嚴(yán)格氫營養(yǎng)型產(chǎn)甲烷菌Methanoculleus、Methanobrevibacter、Methanobacterium是高溫原位加氫甲烷化系統(tǒng)的主要產(chǎn)甲烷菌，且外源氫氣的加入會(huì)弱化同型產(chǎn)乙酸菌與氫營養(yǎng)型產(chǎn)甲烷菌之間的互營協(xié)作關(guān)系，而作為種間電子傳遞載體的甲酸鈉的加入有助丙酸降解產(chǎn)乙酸，從而保證系統(tǒng)的穩(wěn)定。

Through microbial diversity analysis, it was shown that strictly hydrogenotrophic methanogens Methanoculleus, Methanobrevibacter, and Methanobacterium are the main methanogens in high-temperature in-situ hydrogenation methanation systems. The addition of exogenous hydrogen weakens the cooperative relationship between homotrophic methanogens and hydrogenotrophic methanogens, while the addition of sodium formate as an interspecies electron transfer carrier helps to degrade propionic acid and produce acetic acid, thereby ensuring system stability.

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