Effect of fluidization on pressure drop and power consumption in packed bed columns

Abstract

This research investigated the effect of different initial heights of packed bed on pressure drop and minimum fluidisation velocity in packing bed columns. Glass beads with different sizes (6 and 8 mm dp) with density 2, 550 kg/m3 were used, with distilled water as the liquid. In order to study the effect of changing the properties of water, a heater with a temperature controller was used to control the temperature of water for each experimental run at one of two levels (20 and 30 °C) to examine any changes occurring in terms of values of pressure drop at minimum fluidisation velocity.All experimental runs were carried out in a cylindrical Perspex column with a 5 cm inside diameter, 5 mm wall thickness, and 100 cm length; six pressure sensors of transducer type (analogue) were fixed on wall of the column and at bed height in order to measure the pressure; the pressure differences between any two points were thus calculable. The pressure sensors were located 10 cm apart, beginning at the bed mesh holder. The pressure data were recorded using the LabVIEW program and an Arduino.A comparison was made between a stationary (fixed) and fluidised bed by measuring the pressure drop in each case via pressure sensors at the same flow rate, temperature level, and initial height of bed. It was observed that the minimum fluidisation did not change with changes in the initial height, though pressure drop increased with the increase in initial height and both pressure drop and minimum fluidisation velocity increased with increase in temperature. The fluidisation state showed a lower pressure drop than the fixed state, reducing power consumption. For validation Octave Levenspiel’s equations for both pressure drop and minimum fluidisation velocity were applied, showing good agreement with the experimental work in terms of using the liquid as a working fluid.