Bulk Liquid Carbon Dioxide [ Return towards Bulk Gases ]

Air Liquide UK has taken a leading role in every stage of the production of this specification, which is now accepted by leading authorities throughout the world, and which will become the new European Standard for CO2 in due course.

Sources

All the Liquid Carbon Dioxide supplied by Air Liquide UK is a recovered by-product from other processes. The main source is the thermal cracking of hydrocarbons, where the principal product is hydrogen for captive use in chemical plants. Fermentation in breweries and distilleries is the other important source. Chemical and fermentation sources are preferred as the raw CO2 gas stream is relatively pure and high in CO2 content.

Production & Distribution

The raw CO2 is purified in several stages, compressed and cooled to produce liquid CO2 at a pressure of about 20 bar gauge and a temperature of about - 20ºC. It is collected in a large tank which, when full, is isolated, analysed and released for distribution. All Liquide UK plants have continuous on-line process analysis as well as batch release. Carbon dioxide is generally stored and transported at a relatively constant temperature and pressure, i.e. about 20 bar and -20 ºC, as above. Static tanks and road tankers are insulated to keep the product cold, and most static tanks have a small refrigeration plant to offset heat ingress and maintain these conditions. Generally, this means CO2 tanks are closed no-loss systems, unlike most other bulk gas tanks.

Quality

Bulk liquid carbon dioxide as supplied to the food and beverage industries now has the most detailed and stringent product specification of any of the common bulk gases. Air Liquide UK has taken a leading role in every stage of the production of this specification, which is now accepted by leading authorities throughout the world, and which will become the new European Standard for CO2 in due course. Air Liquide UK have already developed and installed the advanced sampling and analytical techniques necessary and can supply product that meets the specification NOW.

Properties

Gaseous CO2 is ….

Tasteless, odourless, colourless
Non-flammable and relatively inert when dry
Highly soluble in water, forming carbonic acid ( H2CO3)
About 11/2 times denser than air
A natural bacteriostat

Liquid CO2 ….

Cannot exist at atmospheric pressure
"Flashes" to a mixture of cold gas and solid CO2 (dry ice) when de-pressurised
Has solvent properties similar to hexane
Becomes "supercritical" when pumped and heated above the critical point - an even better solvent