Hydrodynamics and oxygen transfer in a novel extra-loop fluidized bed bioreactor
Résumé
In this paper, the characteristics of fluid mixing time in a novel extra-loop fluidized bed were studied. The results showed that the mixing time was shortened with the increase of fluid velocity. All the discrete numbers of the reactor were above 0.2. The serial number n was 2.5-3.0. It was judged accordingly that the reactor fluid state was continous stirred tank reactor (CSTR) mainly. When the inspiratory capacity increased the mixing time of the reactor was shortened. Thus the air input was beneficial for the fluid mixing. During the three phases mixing process, the mixing time of the reactor could be decreased by the n increase of carrier and air loading together, but the change was not significant. The parameters affecting the reactor fluid state were fluid velocity, inspiratory capacity and carrier. K La could be increased with the air loading increase, and at the same gas/liquid ratio when the pressure drop was high, K La value was increased. The amount of carrier complex influence on K La. As the carrier loading continued to increase, its value had been dropped but the changes was not significant, and optimization condition was found at above 800-1 000 g carrier loading (pouzzolane) or 600 g PVC. Under gas/liquid ratio of 0.8%-5.2%, K La was (0.62-1.37)×10−2 s−1.