Biogas contains hydrogen sulfide, whose molecular formula is H2S. Hydrogen sulfide is flammable and dangerous chemicals. It can form explosive mixture when mixed with air. It can cause combustion and explosion in case of open fire and high heat. In addition, hydrogen sulfide will produce strong corrosion characteristics on steel when it meets with water. Therefore, the core of the pretreatment process of biogas purification is to remove hydrogen sulfide.
The concentration of hydrogen sulfide in biogas produced by different organic wastes under anaerobic condition varies greatly. Due to the addition of sulfur-containing medium in the production process of paper industry and fermentation industry, the concentration of hydrogen sulfide in biogas produced by production wastewater is relatively high. For example, the biogas in papermaking industry can be as high as 10000-35000ppm, that in starch industry is generally around 10000ppm, and that in domestic waste landfill is relatively less sulfur medium involved in the production process, so the content of hydrogen sulfide is relatively low, generally within 1000ppm.
In China, the production and processing technology and commercial operation system of biogas have gradually matured. Through independent innovation, introduction and digestion of foreign mature and advanced anaerobic digestion technology of organic waste with high solid content, the large-scale biogas project with grain straw, livestock manure and urban organic waste as treatment objects has also made breakthrough progress. Therefore, the corresponding countermeasures are put forward The technology of biogas purification and purification has also been developed, forming a series of relatively mature technologies.