Combination of a biogas plant and a membrane filter unit for removal of carbon dioxide

摘要

The invention relates to a combination of a biogas plant and a membrane filter unit, wherein the biogas plant produces a gas flow comprising methane and carbon dioxide, the membrane filter unit comprising:
- a first membrane filter stage with a first inlet connected to the biogas plant for receiving the gas flow, a first retentate outlet and a first permeate outlet;
- a second membrane filter stage with a second inlet connected to the first retentate outlet, a second retentate outlet and a second permeate outlet connected to the first inlet;
- a third membrane filter stage with a third inlet connected to the first permeate outlet, a third retentate outlet connected to the first inlet and a third permeate outlet; and
- a fourth membrane filter stage with a fourth inlet connected to the second retentate outlet, a fourth retentate outlet and a fourth permeate outlet.