System for recovering methane from a biogas

A system for recovering methane from a biogas, comprising:

• a first pressure swing adsorption (PSA) unit adapted to:
• recover methane from the biogas,
• direct a first fraction of the recovered methane from a first outlet of the first PSA unit toward a product gas outlet,
• direct a second fraction of the recovered methane from a second outlet of first the PSA unit toward a recycling line, and
• direct a remainder of the biogas from a third outlet of the first PSA unit toward an exhaust:
• a biogas inlet fluidly connected to a biogas source;
• a gas mixer fluidly connected to the biogas inlet, to the recycling line and to the first PSA unit, the gas mixer being adapted to:
• form a combination of biogas received at the biogas inlet and of the second fraction of the recovered methane, and
• supply the combination to the first PSA unit for methane recovery;
• and
• a surge tank within the recycling line, the surge tank having an inlet fluidly connected to the second outlet of the first PSA unit, the surge tank further having an outlet fluidly connected to an inlet of the gas mixer, the surge tank being operative to cause a pressure reduction at the second outlet of the first PSA unit and to deliver the second fraction of the recovered methane to the inlet of the gas mixer.