CO2 Liquefaction

After biogas upgrading via membrane separation, the CO₂‑rich off‑gas can be turned into valuable liquid carbon dioxide. Our mature CO₂ liquefaction plant uses compression, molecular sieve pre‑treatment, cryogenic condensation, and optional rectification to produce industrial grade (≥99%) or food grade (≥99.9%) liquid CO₂ – ready for welding, fire suppression, EOR, beverage carbonation, and more.

What Is CO₂ Liquefaction from Biogas Off-Gas?

01 Raw gas: CO₂‑rich off-gas from membrane separation
- The off‑gas contains mainly CO₂ with small amounts of methane, nitrogen, trace oxygen, and water vapour. These impurities must be addressed before liquefaction.
02 Multi‑stage compression with interstage cooling
- Raw gas is progressively pressurised. Interstage cooling condenses and removes most of the free water, protecting downstream equipment.
03 Deep pre‑treatment (molecular sieve)
- A molecular sieve adsorber deeply removes residual water vapour and light impurities. This prevents freeze‑ups and blockages in the cryogenic section – ensuring long‑term continuous operation.
04 Cryogenic condensation (‑20°C to ‑35°C)
- Under controlled pressure, the purified CO₂ is cooled in a cold box to between -20°C and -35°C, where it condenses into liquid. Without rectification, purity is ≥99% (industrial grade).
05 Optional cryogenic rectification (for food grade ≥99.9%)
- To achieve ≥99.9% purity, an additional rectification (distillation) column removes methane, nitrogen, and other light impurities – producing food grade liquid CO₂.
06 Low‑temperature pressurised storage & dispatch
- The final liquid CO₂ is stored in insulated, pressurised tanks. From there it can be loaded onto trucks by differential pressure (self‑flow) or delivered via pipeline to end users.

≥99%

Industrial Grade Purity (no rectification)

≥99.9%

Food Grade Purity (with rectification)

-20°C to -35°C

Liquefaction Temperature Range

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