Multiphase Bioreactor Design

0.042 0.67 0.68 0.70 0.70 0.02 0.83 0.83 0.99 0.98 0.02

0.050 0.67 0.67 0.70 0.69 0.03 0.82 0.82 0.96 0.97 0.04

0.025 0.69 0.70 0.72 0.72 0 0.84 0.85 1.02 1.00 0

0.033 0.69 0.70 0.71 0.72 0 0.83 0.85 0.99 1.00 0

0.042 0.70 0.70 0.72 0.72 0 0.84 0.85 1.02 1.00 0

0.029

0.050 0.70 0.70 0.73 0.72 0 0.83 0.85 1.00 1.00 0

Experimental RTD curves agreed well with those calculated from the model equations
for respective values of the backflow coefficient obtained from independent
measurements. The comparison of characteristic coordinates of experimental and
calculated curves (θYmax and Yθ=1) presented in Table 1.3, demonstrates a good fit of
experimental RTD data with appropriate mixing models (tanks-in-series with backflow
and tanks-in-series, respectively) within the whole region of recommended working
conditions.

Gas Holdup

Experimental results proved the favourable effect of gas redispersion by internal plates on
values of gas holdup ratio (Figure 1.2). The effect of solid phase content was negative
within the whole experimental region of its concentration. The increase of effective slurry
viscosity (see Eq.(3)) with increasing solid phase concentration was too small (μsl=
1.006–1.026 mPa s for cs=1–5 wt.%) to justify the analogy with the coalescence
enhancement in viscous media, proposed in the literature as a possible explanation of the

New methodologies for multiphase bioreactors 1 9