• Follow us
Home > Expertise > Content
Agitation and mass transfer in simulated fermentation broths
Jan 22, 2016

Gas-liquid mass transfer, agitator power consumption, rheology, gas-liquid mixing and gas hold-up have been studied in an agitated, sparged vessel of diameter, T = 0.3 m, with a liquid capacity of 0.02 m3, unaerated liquid height = 0.3 m. The solutions of sodium carboxymethylcellulose used exhibit moderate viscoelasticity and shear thinning behaviour, obeying the power law over the range of shear rates studied. The gas-liquid mass transfer was studied using a steady state technique. This involves monitoring the gas and liquid phase oxygen concentrations when a microorganism (yeast) is cultured in the solutions of interest. Agitator power consumption was measured using strain gauges mounted on the impeller shaft. Various agitator geometries were used. These were: Rushton turbines ( D = T/3 and D = T/2 ), used singly and in pairs; Intermig impellers ( D = 0.58T ), used as a pair; and a 45 degree pitched blade turbine ( D = T/2 ), used in combination with a Rushton turbine. Gas hold-up and gas-liquid flow patterns were visually observed. In addition, the state of the culture variables, (oxygen uptake rate and carbon dioxide production rate), were used to provide a respiratory quotient, the value of which can be linked to the degree of gas-liquid mixing in the vessel. Measurement of point values of the liquid phase oxygen concentration is also used to indicate the degree of liquid mixing attained.


See more at: http://etheses.bham.ac.uk/863/