FIELD: chemistry.
SUBSTANCE: invention relates to method and system for separation and purification of methane from biogas. Raw biogas flow includes methane, carbon dioxide, water, hydrogen sulphide and non-methane organic compounds (NMOC). Method includes collection of raw biogas flow, separation of raw biogas flow, in which raw biogas flow is separated into flow of sulphur-containing compounds and main gas flow. Flow of sulphur-containing compounds is removed from further processing, and main flow is purified from hydrogen sulphide. After that, absorption of liquid NMOC flow from main gas flow is performed. Liquid NMOC flow is removed from further processing, and main gas flow is in fact purified from NMOC. Then, adsorption of NMOC from main gas flow is performed. Liquid NMOC flow is removed from further processing, and main gas flow is in fact purified from NMOC. Then main gas flow is divided into offgas flow, consisting of carbon dioxide, nitrogen and gaseous oxygen and product flow consisting of purified methane gas. Adsorption of offgas flow is performed with formation gas flow to be removed and recirculation flow. Recirculation flow is mixed with main gas flow after stage of separation of raw biogas flow and before stage of absorption of liquid NMOC flow.
EFFECT: increased degree of gas separation for obtaining practically purified methane from biogas.
18 cl, 1 dwg, 1 ex
