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.
Carbon Dioxide Production Rate – Multiple Fermenter Room (Block)
Usually, each fermenter within a block is connected to a common CO2 collection main. This allows us to collect CO2 from every tank, but it also complicates the flow rate of CO2 collected and piped to the collection plant. Typically, two factors cause this complication:
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Out-of-sync fermenters – the fermentation process within any fermenter will be at a differing stage at any point in time to another fermenter. This is because they are filled from brewhouses at different periods. Therefore, the rate of CO2 production from any fermenter will be different as well as the rate of CO2 produced from the fermenter block.
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Volume variation within the cellar – during periods where the brewery is ramping up volume to meet a production volume peak, or ramping down following a peak, the number of fermenters being filled and actively fermenting increase and decrease, respectively.
Illustrative examples of both situations are shown in the figures below.
Figure: The CO2 production rate from individual fermenters (lower plot) and the cumulative CO2 rate in the collection main showing the variability of collected flow rate
Figure: The impact of volume flex, in this case an increase in the frequency of filling of fermenters leading to an increase in the collected CO2 flow rate