Lesson 10 - Carbon Dioxide Recovery Technology
This lesson explores the technology used to recover and purify carbon dioxide (CO2), which is a co-product from brewery fermentations. Purified CO2 is used throughout the brewery to carbonate liquids and to purge air (oxygen) from vessels and packaging containers. It examines the role that fermentation and fermenter vessel operation has on the availability of CO2 for collection, as well as considering an overview of the technologies and plant involved in collecting, purifying, and liquefying CO2 for use back in the brewery.
Drying
The gas is dried using a desiccant to adsorb the water moisture.
Prior to entering the condenser, introduced previously as the cooling process to sub-zero temperatures, it is important to dry the CO2 so that upon condensation it does not form ice in or downstream of the condenser. In order to remove water vapour from the CO2, a two-vessel adsorption process, similar to the deodoriser, is used. Instead of activated charcoal, as in the deodoriser, activated alumina (aluminium oxide) is usually used to bind water vapour.
Regeneration is done using hot CO2 gas rather than steam, and off-site reactivation is not commonly practised, and the alumina is replaced.