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.
Balloon Storage
We wish to eliminate any pressure and flow fluctuations in the collection main so that a steady supply of raw gas is produced. A flexible balloon is used to do this.
The collection balloon’s principal function is to buffer, or smooth out, any pressure fluctuation in the collection main so that the pressure of the gas supplied to the rest of the collection plant is stable. Pressure fluctuations can be caused by the presence of beer foam in the collection main and/or the switch over of fermenters from vent-to-collection or vice versa.
The balloon is quite literally a balloon. It looks more like a sewn bag of several metres in size and is made out of rubberised canvas, but it is flexible enough to expand and contract sufficiently to smooth out the pressure downstream of it. Typically, the balloon operates at quite a low pressure (up to a maximum pressure of typically 5-10 kPa g), and it is fitted with a common inlet-outlet to the main from the foam trap, as shown in the figure below.
Figure: CO2 balloon