control loop enquiry

[maymay]

The fermenter is a fed batch mode. Actually it is a citric acid fermentation process. Molasses and Aspergillus Niger would as feed. I wonder should there a flowrate control loop over the addition of feed?? Also, air would be pumped in continuously and the unused air would then leave the fermenter. I wonder can i have a flowrate controlling loop over the gaseous output in order to release the pressure of the fermenter and to maintain the pressure at an optimum 1 atm?? However, I would be doubt that carbon dioxide should be released out of the fermenter as soon as possible as accumuulation of it would lead to inproper fermentation. If a control loop is over gaseous output so as to control pressure, in case of low pressure, the valve should not be opened large but how would the carbon dioxide left the fermenter??

 

[krecian]

MayMay,

You say it is a batch fermentation. Have a level switch at the desired level (a level transmitter would be better) to actuate the feed control valve.

For maintaing constant pressure, on the gas side, have a control valve actuated by a pressure transmitter mounted on the vessel vapor space-side. This CV can also be actuated in co-ordination with an oxygen anlyser (with suitable control logic) to maintain required minimum O2 on the gas side. The Cv vents the gas (CO2 mainly) to a safe place.

Hope this helps,

KRECian