Patent ID: 8231706

Claim:
A method of separating methane and carbon dioxide from biogas, which comprises the steps of: scrubbing in an absorption column in which the biogas ascends through a packed bed in counter flow to a wash liquid which is fed in and binds the carbon dioxide and hydrogen sulphide, and for subsequent regeneration of the wash liquid; conducting the biogas into the absorption column under atmospheric pressure and standard temperature, wherein the carbon dioxide present in the biogas is bound in the wash liquid by chemosorption as the biogas ascends through the packed bed; separating off the methane gas at a top of the absorption column at a defined flow velocity; subsequently removing the carbon dioxide still bound in the wash liquid by desorption at a relatively high pressure of 2 to 30 bar and a temperature of at least 120° C.; and measuring a CO 2 concentration in the methane gas and a flow velocity of the removed methane gas, and thus the contact time, is set according to a value measured.