Biogas contains hydrogen sulfide with the molecular formula of H2S. Hydrogen sulfide is a flammable hazardous chemical. It can form an 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 have strong corrosion characteristics on steel when it meets water. Therefore, the core of the pretreatment process of biogas purification and refining biogas natural gas is to remove hydrogen sulfide.
The concentration of hydrogen sulfide in biogas produced by different organic wastes in anaerobic state varies greatly. Due to the addition of sulfur-containing medium in the production process of papermaking industry and fermentation industry, the concentration of hydrogen sulfide in biogas produced by production wastewater is relatively high.
For example, the biogas in the paper industry can be as high as 10000-35000ppm, the biogas in the starch industry is generally about 10000ppm, and the biogas in the domestic waste landfill is relatively less involved in the production process, so the content of hydrogen sulfide is low, generally within 1000ppm.
In China, the production and processing technology and commercial operation system of biogas have gradually matured. Through independent innovation, the introduction and digestion of foreign mature and advanced anaerobic digestion technology of organic waste with high solid content have been absorbed. Among them, the large biogas project with grain straw, livestock manure and urban organic waste as the treatment object has also made breakthrough progress. Therefore, The corresponding biogas purification technology has also been developed, forming a series of relatively mature technologies.
The commonly used biogas desulfurization methods in the industry include dry desulfurization, wet desulfurization, complex iron desulfurization, biological desulfurization and other desulfurization methods.