Particle size distribution effect on catalytic conversion in a CSTR

The effect of the particle size distribution on catalytic conversion in a CSTR was studied by comparison with that obtained from an assumed single size. Differences were handled as an error analysis. Calculations were performed according to the following assumptions: first order reaction, spherical pellets with sizes distributed in agreement with gamma function, and the assumed single size value equal to the mean size in the distribution. At each test, major error was found in the region of large competition between reaction and mass transfer rates (Thiele modulus value from 1 to 4). Error increases as feedstock rate increases. Error magnitude as high as 30% were found within the set of parameters tested. To keep error in conversion calculations within 5%, particle size variation should be kept within 35% of the mean size value. To keep it within 1%, particle size variation should be kept within 15% of the mean size value.