CO₂ Liquefaction

Air Liquide units integrate CO₂ liquefaction bricks positioned after the biogas purification process into biomethane allowing CO₂ recovery. This CO₂ liquefaction brick can be applied to effluents of a bioethanol production plant or a biomass boiler.

Liquefaction of biogenic CO₂

The bio-CO₂ liquefaction process is carried out in 4 stages:

Compression and pre-treatment: the bio-CO₂ is compressed to around 15 bar. An activated carbon filter separates out pollutants (hydrogen sulfide H2S and volatile organic compounds VOCs). It is then dried
Purification: the dry gas is cooled, then injected into a distillation column. The liquid bio-CO₂ is purified in the distillation column, reaching purity for food/beverage use at the bottom of the column. The other gas compounds, the non-condensable gases (methane, oxygen, nitrogen, hydrogen...) are separated from the gaseous CO₂ at the top of the column
Distribution: purified bio-CO₂ is pumped to storage tanks. These tanks feed tanker trucks which then transport the bio-CO₂ to consumption sites: food industries for food preservation and beverage carbonation, but also industry (water treatment, industrial cleaning, welding...etc)
Treatment of non-condensable gases: in biomethane production units, non-condensable gases are recycled at source, at the biogas purification unit, to extract the residual methane

Applications

Bio-CO₂ from methanization has several outlets and a variety of applications:

For agricultural production and accelerating plant growth in greenhouses. The CO₂ present in the atmosphere must be compensated for as it is consumed by plants. Air Liquide proposes the enrichment of air with pure carbon dioxide; heated greenhouses use CO₂ to improve plant growth by increasing photosynthetic yield and shortening the growing period. The reduction in natural gas consumption in greenhouse boilers leads to an increase in the volume of liquefied CO₂ for this use
For the food and beverage industries. It is used, for example, for food preservation or deep-freezing, remineralization of drinking water with CO₂, or carbonation of beverages (beer, sparkling water, soda)
In relation to the cold chain: for cryogenic refrigerated transport, refrigeration and deep-freezing. For dry ice, which is the solid form of CO₂ and has several uses: vaccine preservation, cryogenic cleaning, visual and scenic effects
For wastewater treatment : bio-CO₂ from methanization helps improve the efficiency of treatment processes thanks to its acidifying properties and high purity. It thus promotes the precipitation of heavy metals and optimizes biological processes
For various industrial and specific processes: welding, medical applications, paint solvents, cryotherapy, cryo-grinding, event fumes, chromatography, fire extinguisher manufacture, pest control, propellant gas, enhanced fuel recovery

Organic CO₂ for the food industry: bio-CO₂

Air Liquide is establishing itself as a key player in the energy transition by recovering CO₂ from biomass during biogas purification. This CO₂ of biological origin, free of any trace of fossil fuels, is a valuable resource for the food industry. Its isotopic signature attests to its natural origin and guarantees a minimal carbon footprint.

This circular approach provides the food industry with a renewable source of CO₂ and contributes to the production of more environmentally-friendly foods.

By replacing fossil CO₂, traditionally used in food processes, Air Liquide is thus helping to reduce the carbon footprint of the food chain.

Key benefits - an efficient, sustainable liquefaction unit

A bio-CO₂ quality in line with the strictest international standards and adapted to the most demanding food and industrial uses.
Maximum safety, performance and reliability.
Optimized energy consumption.
A long-lasting, ammonia-free refrigerant.
A wide range of possible gas composition from 87% to 98% CO₂ content.

Technical features and performance

Optimized power consumption.
Allows increased treatment capacity of the biogas purifier.
Flexible operation: the purifier can continue to operate when the CO₂ liquefier is shut down.
Maximized CH4 recovery rate: up to 100%.
Maximized CO₂ recovery rate: approx. 98% (depending on the CO₂ content in the biomethane).
Optimized investment cost and TCO.
R744, CO₂ based low-temperature chiller.

Associated services

Air Liquide offers you services associated with its CO₂ liquefaction technology:

Preventive and curative maintenance
Remote maintenance
24/7 hotline
Spare parts
Operating support and expertise
Training