Temperature control in packed-bed solid-state bioreactors

Normal operation of packed-bed bioreactors used for solid-state fermentation involves a static bed aerated from the bottom throughout the fermentation. Due to the rapid heat generating dynamics, temperature control of the bed is very important. In this paper two control algorithm namely conventional proportional- integral (PI) and globally linearizing control (GLC) are used for temperature control of a packed-bed bioreactor, in which Aspergillus niger grows on wheat bran. The study was done using the kinetic and distributed dynamic heat transfer models to reproduce the main operating features of this type of bioreactor. In the selected control loop, the average bed temperature was controlled by manipulating the inlet air temperature. The simulation results showed that, although the PI controller has the simpler structure, the GLC controller has the slightly better performance. In addition, this work showed that with controlling the average bed temperature instead of controlling the top-bed temperature, the whole temperature of the bed can be kept in the suitable range of Aspergillus niger.

Keywords:

Solid-state fermentation , Packed-bed bioreactor , PI control , Nonlinear control