The main components of biogas are CH4 and CO2, and in addition, they contain trace amount of H2O, water and other impurities. The technical difficulty of producing gas, GNG and LNG from biogas is the purification of biogas. Therefore, it is necessary to make biogas a high-quality biogas with high methane content and high heat value and impurities in line with the requirements of pipeline, compressed or liquefied natural gas standards through necessary purification technology.
Biogas purification is generally to remove the harmful components in biogas, so as to improve the applicability and heat value of gas. The purified biogas can be used as a substitute for natural gas. There are several aspects of purification process, such as biogas desulfurization, biogas deoxidation, biogas drying, biogas decarbonization and other impurities removal. 1. Desulfurization process: the gas produced during fermentation is removed by gravity water removal in drying cabinet and water and deodorization by high energy ion deodorization equipment, and then enters into double membrane gas storage bag for temporary storage. Because the biogas raw gas contains a certain amount of H2S gas, it is necessary to remove and purify the H2S gas through desulfurization process. The gas enters from the bottom of the dry desulfurization tower and is discharged from the top. The gas contacts with the dry desulfurizer in the dry desulfurization tower, which makes H2S removed. 2. After the biogas decarbonization, the desulfurized methane is stabilized by the gas tank, and then the saturated water vapor and micro dust particles are removed by high-efficiency filter, and then it enters the membrane separation device, which makes the mixture gas CH4 and CO2 separate from each other. After separation, the final concentration of CO2 in the biogas is less than 3%, and the separated CO2 contains almost no CH4.
Biogas purification and purification can produce biomethane, which is equivalent to fossil natural gas in quality. Under the condition, it can be directly incorporated into pipeline gas, or compressed natural gas, which can be used for automobile fuel. There are many technologies for biogas purification, and Kaifeng DEAR Air Separation can be designed and selected according to the user's own cost of funds and the target of energy utilization.
