Measurement of liquid holdup and axial dispersion in trickle bed reactors using radiotracer technique

The holdup and axial dispersion of aqueous phase has been measured in trick le bed reactors as a function of liquid and gas now rates using radioisotop e tracer technique. Experiments were carried out in a glass column of inner diameter of 15.2x10(-2) m column for air-water system using three differen t types of packings i.e, non-porous glass beads, porous catalysts of tablet and extrudate shape. The range of liquid and gas flow rates used were 8.3x 10(-5)-3.3x10(-4) m(3)/s and 0-6.67x10(-4) m(3)/s, respectively. Residence time distributions of liquid phase were measured and mean residence times w ere determined. The values of liquid holdup were calculated from the measur ed mean residence times. It was observed that the liquid holdup increases w ith increase in liquid flow rates and was independent of increase in gas fl ow rates used in the study. Two-parameter axial dispersion model was used t o simulate measured residence time distribution data and values of mean res idence time and Peclet number were obtained. It was observed that the value s of Peclet number increases with increase in liquid flow rate for glass be ads and tablets and remains almost constant for extrudates. The values of m ean residence time obtained from model simulation were found to be in good agreement with the values measured experimentally.