Measurement and control of oxygen in carbon dioxide.
Huige, N.J., Charter, W.M. and Wendt, K.W.
Concentrations of O2and other impurities in CO2were measured at various locations in the CO2purification system (Miller's Brewery, USA. A Zahn CO2purity tester and four different polargraphic O2analysers were used and their performance evaluated. CO2purity depended on brew type, fermenter design, fermentation pattern, head space volume and O2trapped when the fermenter was being filled. A number of fermentation processes are illustrated. For economy fermenters should be switched to CO2collection when the O2concentration in the combined CO2flow is below a selected level. (In this plant an in-line O2analyser is installed after the booster compressors). Water used in foam traps and water scrubber systems increase O2in CO2by about 6 and 22 ppm resp. O2pick-up in the water scrubber was reduced by deaerating the water with waste vent gas from the CO2condenser. By continuous venting of CO2from the condenser headspace at 2.5% of the condenser feed rate the O2concentration in CO2was reduced on average by 20%. A distillation column designed to reduce O2in CO2with minimal CO2loss is being investigated.
Keywords: analysis brewing carbon dioxide control oxygen purification recovery volatile compound