一、沼气的组成特性与脱硫必要性

1、 Composition characteristics of biogas and necessity of desulfurization

沼气作为一种重要的可再生能源，其主要成分为甲烷（CH₄）和二氧化碳（CO₂），同时含有少量硫化氢（H₂S）等有害气体。其中，硫化氢具有极强的毒性，当空气中H₂S浓度达到0.1%时即可致人死亡。除了危害人体健康外，硫化氢还会对金属管道、沼气发电机、锅炉等用气设备造成严重腐蚀。更值得注意的是，硫化氢在燃烧过程中会转化为二氧化硫（SO₂），这种物质不仅具有强腐蚀性，还会导致酸雨形成，对环境造成二次污染。根据我国严格的环保标准规定，沼气能源利用时总硫含量不得超过20mg/m³。然而，实际沼气中的硫化氢浓度通常在1～12g/m³范围内，远超国家标准限值。因此，为保障人员安全、保护生态环境并延长设备使用寿命，沼气在综合利用前必须进行脱硫处理。

Biogas, as an important renewable energy source, is mainly composed of methane (CH4) and carbon dioxide (CO ₂), 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 ₂) 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、主流脱硫技术分类及特点

2、 Classification and characteristics of mainstream desulfurization technologies

目前沼气脱硫技术主要分为三大类，每种技术都有其独特的工艺特点和适用范围：

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

干法脱硫技术

Dry desulfurization technology

干法脱硫是将特制脱硫剂（如氧化铁）填充在脱硫塔内，当沼气通过填料层时，其中的硫化氢与脱硫剂发生物理吸附或化学反应而被去除。该技术具有以下特点：

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:

适用于硫化氢浓度较低（通常＜500ppm）的情况

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

处理气量相对较小

The processing gas volume is relatively small

脱硫精度高，可达1ppm以下

High desulfurization accuracy, up to 1ppm or less

工艺流程简单，操作方便

Simple process flow and easy operation

会产生废旧氧化铁脱硫剂，需专业处理

Waste iron oxide desulfurizer will be generated and requires professional treatment

湿法脱硫技术

Wet desulfurization technology

湿法脱硫是通过含有催化剂的液相将沼气中的硫化氢氧化为单质硫的工艺，主要包括吸收和再生两个关键过程。其技术特点包括：

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:

适用于中高浓度硫化氢（500-5000ppm）的脱除

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

处理能力大，适合规模化应用

Large processing capacity, suitable for large-scale applications

脱硫效率较高，但精度不及干法

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

运行成本相对较低

Relatively low operating costs

会产生硫磺副产品，需进一步处理

It will produce sulfur by-products and require further processing

生物脱硫技术

Biological desulfurization technology

生物脱硫是近年来在欧洲、日本等发达地区兴起的新型脱硫技术，其原理是利用硫杆菌属和丝硫菌属等微生物的新陈代谢作用去除硫元素。该技术的优势在于：

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:

环境友好，基本无二次污染

Environmentally friendly, with minimal secondary pollution

运行成本最低

Lowest operating cost

产生的含硫液体可现场利用或进入好氧系统

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

适合各种规模的沼气工程

Suitable for biogas projects of various scales

需要严格控制运行参数

Strict control of operating parameters is required

三、技术比较与选择建议

3、 Technical Comparison and Selection Suggestions

在选择脱硫工艺时，需综合考虑以下因素：

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

沼气中硫化氢的初始浓度

Initial concentration of hydrogen sulfide in biogas

处理气量大小

Processing gas volume size

要求的脱硫精度

Required desulfurization accuracy

投资和运行成本预算

Investment and operating cost budget

副产品处理方案

By product processing plan

现场条件和管理水平

On site conditions and management level

对于小型沼气工程（日产气量＜500m³），建议优先考虑干法脱硫；中型项目（500-2000m³/d）可选用湿法脱硫；大型沼气工程（＞2000m³/d）则推荐采用生物脱硫或组合工艺。在实际应用中，有时会采用两级脱硫系统，先用湿法进行粗脱，再用干法进行精脱，以达到最佳的经济技术效果。

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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