The heart of our system is the membrane separation unit. Membrane technology for biogas processing is a relatively new technology, but it has already proven itself. The gas treatment market has already recognized the advantages of membrane technology over other separation systems such as water scrubbing, amine scrubbing and pressure swing (PSA) systems.
Membranes for gas separation
To make an efficient CO2/ CH4 separation possible, the impurities must first be removed. One of the most important techniques for doing this is the use of activated carbon that absorbs undesirable substances. The membranes separate the two major gas components: CH4 and CO2. The separation is accomplished through the pressure difference over the membrane surface.
The high-pressure biogas is fed into the membrane and the CO2 passes through the membrane surface to the permeate - the low-pressure side - much quicker than CH4. The membranes are mainly pressure-driven, so the higher the pressure the more CO2 will pass through the membrane surface.
The discharge from the membrane (the retentate) contains mainly CH4 as the CO2 has been pushed through the membrane surface. The CO2-rich gas will leave the membrane on the low-pressure side of the membrane (permeate).
Pentair provides a two-stage membrane system together with a cryogenic system. This system provides two valuable products: biomethane and 100 % liquid CO2.