A model for fluidized bed fermentation

At equilibrium conditions, the rate at which water enters the bed with the feed Wu,f is equal fo fhe rafe af which it is removed at the condenser, W ,c- The gain in water vapour partial pressure in the fluidizing gas across the bed - p i) depends upon the volumetric flow rate of fluidizing gas Q, fhe fofal pressure in the system P, and the density of water vapour Thus 

Assuming the stoichiometric conversion of glucose to ethanol then V e.hed = 0.511 Wg where Wg is the mass flow rate of glucose into the bed and thus the mass rate of accumulation of carbon dioxide in the system is 0.489 Wg. The overall material balance at equilibrium for a system originally charged with inert gas is then 

At start-up, before any ethanol is generated by fermentation, the initial mass of yeasf (wafer plus yeast dry solids) in the bed is niy. Any ethanol accumulation in the bed is in excess of niy so fhaf af equilibrium the total mass in the bed (yeast plus ethanol) is niy -t m. A material balance for the bed mass is then 

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