ChE 441 Problem Set 2 Solutions

ChE 441: Advanced Transport Phenomena Problem Set #2 1. (2A.4) Loss of Catalyst Particles in a Stacked Gas (a) Estimate the maximum diameter of micro spherical catalyst particles that could be lost in the stack gas of a fluid cracking unit under the following conditions: Gas velocity at axis of stack = 1.0 ft/s (vertically up) Gas viscosity = 0.026 cp = 0.00026 g/cm-s Gas density = 0.045 lbm/ ft3 Density of a catalyst particle = 1.2 g/cm3 Express your result in microns (1 micron = 10-6 m = 1µ) Solution

(I inch = 2.54 cm) Equation 2.6-17:

Rearrange,

Convert to microns:

(b) Is it permissible to use Stoke’s Law in (a)? Solution Equation 2.6-17 used in 9a) was derived for Re