Figure 1.7 Relation between the
energy effectiveness criterion (Φ) and
kLaL six stage column:
single stage column (Zahradník et al.,
1982a); ejector distributor reactor
(Zahradník et al., 1982a).
CONCLUSIONS
Hydrodynamic and mass transfer characteristics of multi-stage three-phase slurry reactors
were studied experimentally as functions of selected construction and operating
parameters including number of column stages, distributing plate geometry, gas and
liquid flow rates and solid phase concentration. Experimental results confirmed
favourable effect of bubble column sectionalisation on the rate of mass transfer between
the gas and the liquid phases and on the energy effectiveness of their contacting. It has
been proved that the liquid phase (slurry) backflow between the adjacent column stages
can be significantly suppressed or even eliminated by the proper design of sectionalising
plates. Axial mixing of the liquid or slurry phase can be then appropriately described by
the model of perfectly mixed tanks in series for the number of series terms equal to the
real number of column stages.
The increasing concentration of solid particles influenced negatively values of gas
holdup and kLaL and thus even the energy effectiveness of gas-liquid contacting. Higher
power input has to be therefore supplied to the three-phase reactors to ensure a gas-liquid
New methodologies for multiphase bioreactors 1 19