Today’s biomethane producers want more than conventional solutions. They strive for an effective CO2 and CH4 recovery management to maximize yield and minimize environmental impact of the biogas plants. Pentair's innovative biogas upgrading technology offers substantial advantages compared to conventional systems.
To make CO2 and CH4 separation possible, impurities need to be removed. One of the essential elements for doing this is activated carbon which adsorbs undesirable substances.
The membrane separates 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 faster than CH4.
The membranes are 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).
After the membrane separation unit, Pentair goes one step further by recovering the CO2 gas with our cryogenic-based CO2Bolt-On system.
The system compresses, purifies, dehumidifies, and liquefies the CO2, helping to reduce the need to release environmentally harmful greenhouse gas.
Instead, the liquified CO2 can be commercialized and used in various applications.
Pentair provides a two-stage membrane system together with a cryogenic system called Pentair BioComplete.
With a multi-membrane system, up to 99 percent of the CO2 can be removed from the biogas.
A two-stage membrane and cryogenic system will produce two valuable products: biomethane and CO2.
Pentair Advanced Amine Technology removes hydrogen sulfide (H2S) or CO2. This purified gas flows out from the top of the tower after being in contact with a monoethanolamine (MEA) aqueous solution that reacts readily with CO2.
Once the CO2 is captured in the MEA solution, it is transferred to a stripping system. Here, the CO2 is again released from the MEA solution by increasing the temperature to a point where the chemical reaction that took place in the absorber is reversed. Having started as a gas with a low concentration of CO2, the gas released from the stripper is now a highly concentrated stream containing up to 99.9 percent pure CO2.
This stream can either be used directly in gaseous form or be further purified and liquefied to meet the strictest requirements.