DYNAMICS OF FIXED-BED REACTORS IN TERMS OF MASS DISPERSION

An important aspect of any design exercise is the reliability of the e mployed data. In the case of fixed-bed reactors, the inadequacies of t he existing design information are now universally accepted. This cont ribution presents an attempt to elucidate the dynamic dispersive featu res of fixed beds by utilising a refined experimental approach togethe r with a representative two-dimensional mathematical model of the phys ical system. Manipulation of the predictions in comparison with the ob served data provided best estimates of the effective axial and radial dispersion coefficients for both the transient and steady-state situat ions. Empirical expressions have been established for the a priori det ermination of the dispersion terms. These are different from those pre dicted by the literature correlations with the discrepancy becoming gr eater with increasing values of Reynolds number. Values suitable for t he transient case are found to be unsuitable for steady-state conditio ns. Interactive effects between the axial and radial dispersion factor s have also been established.