Working Principle
The biogas is compressed to 1.0MPa by the biogas compressor. Then the biogas compressor is fed into the lower section of the water scrubber, countercurrent absorption with pressurized circulating water. The natural gas, after CO2 removed, is collected at the top of the scrubber and injected into the natural gas buffer tank. Then the natural gas passes through the molecular sieve dehydration system to remove moisture completely. This will ensure the final natural gas meeting the purity demands. In the end, the processed natural gas is compressed by the CNG compressor and injected into the city natural gas pipeline network or CNG tanker trucks.
At the bottom of the water scrubber, the water with absorbed CO2 is depressurized to 0.6MPa and injected into the primary flash desorption unit for initial pressure reduction and desorption. Because the desorption characteristics of CH4 and CO2 is different, the partially desorbed gas from the top of the unit is partially recirculated back to the water scrubber for re-pressurization and CO2 removal. The circulating water with dissolved CO2 from the primary flash desorption is then further depressurized to 2kPa and enters the secondary desorption tower, then use the air aeration to strip the remaining dissolved CO₂. The regenerated circulating water is recycled back to the wash tower for reuse.
Treatment Process
