1. The CO2 generation process from Biogas capture in Palm Oil Mill will adopts a composed process of water scrubbing, cryogenic adsorption, and fractional distillation.
2. After buffer, the fermentation biogas is pressurized firstly by the compressor, and then scrubbed by water (this type is grading scrubbing and not much water is needed) to separate methane CH4 in the raw biogas.
3. Secondly pressurized by the compressor to 2.0~2.5Mpa, the biogas goes through cooling dehumidifier to be removed a certain amount of saturated water, and then through molecular sieve drier so that the water content is down to less than 10ppm, and then goes into pre-rectifying tower where meets liquid carbon dioxide coming from return line in the tower to remove those impurities of higher boiling points.
4. When the cryogenic CO2 gas who comes out from pre-rectifying tower goes through absorber and at the lower temperature those impurities of high boiling points further be removed, in which we get gas product qualified.
5. Next, CO2 biogas product goes into liquefier where one part of liquefied carbon dioxide returns the pre-rectifying tower and the other part goes into main rectifying tower to remove those impurities of lower boiling points, thus we get food-grade liquid carbon dioxide product.