一、沼氣的組成特性與脫硫必要性

1、 Composition characteristics of biogas and necessity of desulfurization

沼氣作為一種重要的可再生能源，其主要成分為甲烷（CH?）和二氧化碳（CO?），同時(shí)含有少量硫化氫（H?S）等有害氣體。其中，硫化氫具有極強(qiáng)的毒性，當(dāng)空氣中H?S濃度達(dá)到0.1%時(shí)即可致人死亡。除了危害人體健康外，硫化氫還會(huì)對金屬管道、沼氣發(fā)電機(jī)、鍋爐等用氣設(shè)備造成嚴(yán)重腐蝕。更值得注意的是，硫化氫在燃燒過程中會(huì)轉(zhuǎn)化為二氧化硫（SO?），這種物質(zhì)不僅具有強(qiáng)腐蝕性，還會(huì)導(dǎo)致酸雨形成，對環(huán)境造成二次污染。根據(jù)我國嚴(yán)格的環(huán)保標(biāo)準(zhǔn)規(guī)定，沼氣能源利用時(shí)總硫含量不得超過20mg/m3。然而，實(shí)際沼氣中的硫化氫濃度通常在1～12g/m3范圍內(nèi)，遠(yuǎn)超國家標(biāo)準(zhǔn)限值。因此，為保障人員安全、保護(hù)生態(tài)環(huán)境并延長設(shè)備使用壽命，沼氣在綜合利用前必須進(jìn)行脫硫處理。

Biogas, as an important renewable energy source, is mainly composed of methane (CH4) and carbon dioxide (CO ?), as well as a small amount of harmful gases such as hydrogen sulfide (H2S). Among them, hydrogen sulfide has extremely strong toxicity and can cause death when the concentration of H2S in the air reaches 0.1%. In addition to endangering human health, hydrogen sulfide can also cause serious corrosion to gas equipment such as metal pipelines, biogas generators, boilers, etc. It is worth noting that hydrogen sulfide is converted into sulfur dioxide (SO ?) during combustion, which not only has strong corrosiveness, but also leads to the formation of acid rain, causing secondary pollution to the environment. According to China's strict environmental standards, the total sulfur content during the utilization of biogas energy shall not exceed 20mg/m 3. However, the actual concentration of hydrogen sulfide in biogas is usually within the range of 1-12g/m 3, far exceeding the national standard limit. Therefore, in order to ensure personnel safety, protect the ecological environment, and extend the service life of equipment, biogas must undergo desulfurization treatment before comprehensive utilization.

二、主流脫硫技術(shù)分類及特點(diǎn)

2、 Classification and characteristics of mainstream desulfurization technologies

目前沼氣脫硫技術(shù)主要分為三大類，每種技術(shù)都有其獨(dú)特的工藝特點(diǎn)和適用范圍：

At present, biogas desulfurization technology is mainly divided into three categories, each with its unique process characteristics and applicable scope:

干法脫硫技術(shù)

Dry desulfurization technology

干法脫硫是將特制脫硫劑（如氧化鐵）填充在脫硫塔內(nèi)，當(dāng)沼氣通過填料層時(shí)，其中的硫化氫與脫硫劑發(fā)生物理吸附或化學(xué)反應(yīng)而被去除。該技術(shù)具有以下特點(diǎn)：

Dry desulfurization is the process of filling a specially designed desulfurizer (such as iron oxide) into a desulfurization tower. When biogas passes through the packing layer, the hydrogen sulfide in it undergoes physical adsorption or chemical reaction with the desulfurizer to be removed. This technology has the following characteristics:

適用于硫化氫濃度較低（通常＜500ppm）的情況

Suitable for situations with low hydrogen sulfide concentration (usually<500ppm)

處理氣量相對較小

The processing gas volume is relatively small

脫硫精度高，可達(dá)1ppm以下

High desulfurization accuracy, up to 1ppm or less

工藝流程簡單，操作方便

Simple process flow and easy operation

會(huì)產(chǎn)生廢舊氧化鐵脫硫劑，需專業(yè)處理

Waste iron oxide desulfurizer will be generated and requires professional treatment

濕法脫硫技術(shù)

Wet desulfurization technology

濕法脫硫是通過含有催化劑的液相將沼氣中的硫化氫氧化為單質(zhì)硫的工藝，主要包括吸收和再生兩個(gè)關(guān)鍵過程。其技術(shù)特點(diǎn)包括：

Wet flue gas desulfurization is a process that oxidizes hydrogen sulfide in biogas to elemental sulfur through a liquid phase containing a catalyst. It mainly includes two key processes: absorption and regeneration. Its technical features include:

適用于中高濃度硫化氫（500-5000ppm）的脫除

Suitable for the removal of medium to high concentrations of hydrogen sulfide (500-5000ppm)

處理能力大，適合規(guī)模化應(yīng)用

Large processing capacity, suitable for large-scale applications

脫硫效率較高，但精度不及干法

The desulfurization efficiency is high, but the accuracy is not as good as the dry method

運(yùn)行成本相對較低

Relatively low operating costs

會(huì)產(chǎn)生硫磺副產(chǎn)品，需進(jìn)一步處理

It will produce sulfur by-products and require further processing

生物脫硫技術(shù)

Biological desulfurization technology

生物脫硫是近年來在歐洲、日本等發(fā)達(dá)地區(qū)興起的新型脫硫技術(shù)，其原理是利用硫桿菌屬和絲硫菌屬等微生物的新陳代謝作用去除硫元素。該技術(shù)的優(yōu)勢在于：

Biological desulfurization is a new desulfurization technology that has emerged in developed regions such as Europe and Japan in recent years. Its principle is to use the metabolic processes of microorganisms such as sulfur bacteria and silk sulfur bacteria to remove sulfur elements. The advantages of this technology are:

環(huán)境友好，基本無二次污染

Environmentally friendly, with minimal secondary pollution

運(yùn)行成本最低

Lowest operating cost

產(chǎn)生的含硫液體可現(xiàn)場利用或進(jìn)入好氧系統(tǒng)

The sulfur-containing liquid generated can be utilized on-site or enter the aerobic system

適合各種規(guī)模的沼氣工程

Suitable for biogas projects of various scales

需要嚴(yán)格控制運(yùn)行參數(shù)

Strict control of operating parameters is required

三、技術(shù)比較與選擇建議

3、 Technical Comparison and Selection Suggestions

在選擇脫硫工藝時(shí)，需綜合考慮以下因素：

When choosing a desulfurization process, the following factors should be considered comprehensively:

沼氣中硫化氫的初始濃度

Initial concentration of hydrogen sulfide in biogas

處理氣量大小

Processing gas volume size

要求的脫硫精度

Required desulfurization accuracy

投資和運(yùn)行成本預(yù)算

Investment and operating cost budget

副產(chǎn)品處理方案

By product processing plan

現(xiàn)場條件和管理水平

On site conditions and management level

對于小型沼氣工程（日產(chǎn)氣量＜500m3），建議優(yōu)先考慮干法脫硫；中型項(xiàng)目（500-2000m3/d）可選用濕法脫硫；大型沼氣工程（＞2000m3/d）則推薦采用生物脫硫或組合工藝。在實(shí)際應(yīng)用中，有時(shí)會(huì)采用兩級(jí)脫硫系統(tǒng)，先用濕法進(jìn)行粗脫，再用干法進(jìn)行精脫，以達(dá)到最佳的經(jīng)濟(jì)技術(shù)效果。

For small-scale biogas projects (daily gas production<500m 3), it is recommended to prioritize dry desulfurization; Medium sized projects (500-2000m 3/d) can choose wet desulfurization; For large-scale biogas projects (>2000m 3/d), it is recommended to use biological desulfurization or combined processes. In practical applications, sometimes a two-stage desulfurization system is used, where wet method is first used for coarse desulfurization, and then dry method is used for fine desulfurization to achieve the best economic and technical results.

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