Problem 1.
Mixed flow reactors are relatively cheap compared to plug flow reactors.
Assume MFRs cost $23/L to construct vs. $47/L for PFRs.
Your are conducting a reaction with following parameters:
k = 0.17 sec-1
Co = 16.7 mol/L
q = 10 L/s
You would like to have a 95% conversion.
A. Which reactor would be cheaper to construct?
B. if you purchased 4 equal size MFR reactors to accomplish the task, what would be the cost?
C. If you purchased 4 equal size PFR reactors to accomplish the task, what would the cost be?
Problem 2.
MCO has a new vitamin pill which dissolves slowly (ie. shrinks) to release vitamins over an entire day (12 hours). Assuming the dissolution of the vitamins is rate-limiting (ie. ignore diffusion constraints), calculate the required size (radius) of the spherical pill. You may assume that the dissolution reaction is 1st order and that the vitamin solution leaving the pill is saturated.
Data:
kS = 0.01 cm/s (dissolution rate constant)
Cwater = 0.056 gmol/cm3 (water concentration in bulk fluid, assumed constant)
rB = 0.2 gmol/cm3 (density/concentration of vitamin in pill)
Problem 3
Vitamin solubility is 1 gmol in 100 gmol of waterYou are loading a drug (D) onto a porous spherical carrier pellet from an ethanol solution. The process is controlled by film diffusion f nom the bulk ethanol solution to the pellet.
kf= 9.3 x 104 an/s R = 1.2 cm
CDB = 2.4 gmol/cm3 ps = 0.72 gmol/cm3
Adsorption stoichiometry -> 1 mole drug
requires 3 mole of carrier to bind
1. Calculate the time needed to fully
saturate the pellet with I) (min).
2. Calculate the time needed to reach 85%
saturation of the pellet.