4.3 A 1.5-m diameter bed of micro catalyst (s.g.= 2.0, sphericity =0.9 ) with size distribution given below is to be fluidised using a gas (density =1.2kg/m3, viscosity =1.7105Pa.s ). Initially the bed is 1.0m high with a voidage of 0.4 . a. Calculate the minimum gas flow rate necessary to fluidise the bed of catalyst. The bed voidage at incipient fluidization is not known. b. What is the highest gas flow rate that can be used to safely fluidise the bed? Determine the bed voidage, bed height and bed pressure drop under this condition. Assume particulate fluidisation and verify that it is the case. c. In actual operation, process requirements may demand a higher gas flow rate than that calculated in (b). In order to contain all catalyst particles in the bed, the fluidising section needs to be tapered, i.e. with increasing cross section in the vertical direction. For an operating fluidising gas rate of 1800m3/h, what should the diameter of the upper end of the bed be, if the base has a diameter of 1.5m