| The hydrodynamic and mass transfer characteristics of multiphase bubble column reactors are studied to develop new experimental correlations for scaleup of fermentation, coal liquefaction, and Fischer-Tropsch synthesis reactors. The experiments are carried out in a 0.304 m diameter, 3.4 m high glass bubble column. Phase holdups and bubble size distributions are measured using hydrostatic head technique and dynamic gas disengagement method, respectively. Gas-liquid specific interfacial area is measured using a sulfite oxidation technique, whereas, volumetric mass transfer coefficients are measured using chemical as well as physical aborption of oxygen from air.; The effects of wide range of physical parameters such as superficial phase velocities, physical properties of liquid, and presence of solids on the hydrodynamic and mass transfer characteristics of bubble column reactors are studied. The effect of physical properties of liquid phase is determined by changing surface tension and viscosity of Newtonian and non-Newtonian liquids. The C(,9)('+) iso-paraffins are used to simulate the liquid medium in Fischer-Tropsch synthesis reactors. Four different solids having densities in the range of 1060-2730 kg/m('3) with sizes varying from 30-600 microns are used. The solids concentration is varied from 0-30 wt%.; The highly viscous two and three phase pseudoplastic solutions simulate the fermentation medium. The data collected in the presence of solids and organic liquids will be helpful in the design of hydroprocessing reactors. The effect of bubble size distribution on scaleup is analyzed qualitatively as well as quantitatively. A new model based on a bimodel bubble size distribution is presented to design bubble column reactors which operate in the churn turbulent flow regime. The Fischer-Tropsch synthesis reaction was used as an illustrative example. All available literature correlations for highly viscous liquids, which are based on the data in small diameter columns (D(,c) < 0.15 m), are invalid due to a pronounced diameter effect in the slug flow regime. Wherever necessary, new experimental correlations are established to predict gas holdup, specific gas liquid interfacial area, and volumetric mass transfer coefficients. |
