Patent ID: 8568512

Claim:
A method for methane separation and purification from a biogas, comprising the steps of: collecting a raw Biogas stream, the raw Biogas stream including at least methane, carbon dioxide, water, hydrogen sulfide, and non-methane organic compounds (NMOC); performing a raw Biogas stream separation procedure in which the raw Biogas stream is separated into a sulfur compounds stream and a main gas stream, the sulfur compounds stream being removed from further processing, the main gas stream being purified from the hydrogen sulfide; adsorbing a non-methane organic compounds (NMOC) liquid stream from the main gas stream, the NMOC liquid stream being removed from further processing, the main gas stream being substantially purified from the non-methane organic compounds; performing a main gas stream separation procedure in which the main gas stream is separated into an off-gas stream substantially composed of carbon dioxide, nitrogen, and oxygen gas, and a product stream composed substantially of purified methane gas; performing an off-gas stream adsorbing procedure, thereby forming a vent gas stream and a recycle stream; venting the vent gas stream into the atmosphere without flaring the vent gas stream; and mixing the recycle stream with the main gas stream after the step of performing a raw Biogas stream separation procedure and before the step of absorbing a first non-methane organic compounds (NMOC) liquid stream.