How Does a CO₂ Recovery Plant Work?
From Waste CO₂ Gas to High-Purity Liquid CO₂
A CO₂ recovery plant captures carbon dioxide from an industrial gas stream, removes contaminants, compresses and dries the gas, and finally converts it into purified gaseous or liquid CO₂ for reuse or commercial sale.
Depending on the source gas, recovered CO₂ can originate from brewery fermentation, ethanol fermentation, molasses fermentation, chemical processes, biogas upgrading, dry ice production, or CO₂-rich industrial gas streams.
A typical industrial CO₂ recovery process includes:
Raw CO₂ Collection → Washing & Pretreatment → Compression → Purification → Drying → Liquefaction → Final Purification → Liquid CO₂ Storage
YTC designs CO₂ recovery systems covering approximately 80–20,000 kg/h, with project configurations engineered according to the feed gas and required product specification.
Step 1: Raw CO₂ Collection
The first stage is collecting the CO₂-rich gas from its source.
Fermentation gas from breweries and ethanol plants is naturally rich in CO₂, while flue gas or industrial process gas may contain significantly lower CO₂ concentrations and therefore require additional capture or concentration steps.
Feed-gas composition determines almost every downstream design decision.
Important parameters include:
- CO₂ concentration
- Oxygen
- Nitrogen
- Moisture
- Ethanol and VOCs
- Sulfur compounds
- Oil or compressor contaminants
- Other process-specific impurities
A representative YTC biogas-upgrading project, for example, was based on off-gas containing approximately 91% CO₂ and 8% methane, requiring a different purification strategy from fermentation CO₂.
Step 2: Washing and Pretreatment
Fermentation CO₂ may contain water vapor, ethanol, foam, odors and entrained fermentation materials.
A washing and defoaming system removes these contaminants before compression.
Correct pretreatment protects downstream compressors, adsorbents, heat exchangers and purification equipment.
Step 3: CO₂ Compression
The cleaned gas is compressed to the pressure required for downstream purification and liquefaction.
Compression is one of the major energy-consuming operations in a CO₂ recovery plant, making compressor selection, staging and cooling important to overall plant efficiency.
Step 4: Purification
Different feed gases require different purification technologies.
Depending on the project, YTC systems can incorporate:
- Multi-stage water washing
- Activated-carbon adsorption
- Molecular-sieve adsorption
- PSA purification
- Deodorization
- Impurity separation
- Final rectification
The objective is not simply to increase total CO₂ concentration, but to control individual contaminants according to the required product specification.
Step 5: Drying
Water must be removed before low-temperature liquefaction.
Residual moisture can freeze in low-temperature equipment and cause operating problems. Adsorption drying therefore provides the very low moisture level required for stable refrigeration and liquefaction.
Step 6: CO₂ Liquefaction
Purified and dried CO₂ is cooled under pressure until it condenses into liquid CO₂.
Non-condensable gases such as oxygen and nitrogen remain preferentially in the gas phase and can be separated during the liquefaction and purification process.
Step 7: Final Purification and Storage
Depending on product requirements, additional rectification or stripping can further remove light impurities.
The finished liquid CO₂ is then transferred to insulated storage tanks before being supplied to tankers, tank containers, dry ice systems or downstream users.
YTC systems can be engineered to produce CO₂ purity up to 99.998%, depending on feed-gas composition and process configuration.
YTC CO₂ Recovery Experience
YTC has executed more than 200 CO₂ treatment and recovery projects worldwide, covering fermentation, brewery, ethanol, industrial gas, flue gas and biogas applications.
Its engineering capability ranges from approximately 80 kg/h to 20,000 kg/h, allowing the process to be configured for both relatively small recovery systems and large industrial plants.
The fundamental principle remains the same:
Capture CO₂ that would otherwise be lost, remove the contaminants, convert it into a usable product, and return that CO₂ to the industrial value chain.
