FIELD: process engineering.
SUBSTANCE: invention relates to biogas cleaning for extraction of methane containing, for example, carbon dioxide, compounds of sulfur and ammonium to be separated at several process step. Cleaning is performed in at least three steps. At first step, carbon dioxide, compounds of sulfur and ammonia and other water-soluble organic impurities present in green gas are removed in flushing column at standard pressure or excess pressure of up to 6 bar by sweet water. Note here than methane gas containing methane in amount of 65% is extracted nearby flushing column head. Methane and carbon dioxide dissolved in flushing water are extracted from fouled flushing water released from flushing stage in first flushing column at standard pressure and, then in second evaporation column at vacuum. Oxygen-bearing aeration gas of combustible quality is obtained in first evaporation column. Cleaned flushing water accumulated in second evaporation stage is returned to flushing stage K1.
EFFECT: power savings, 10% increase in methane content.
21 cl, 2 dwg
