Question

S UTM Reaction in CSTR - Group Discussion Question : It is desired to produce 200 million pounds per year of ethylene glycol (EG). The reactor is to be operated isothermally, 1 lb.mole/ft3 solution of ethylene oxide (EO) in water is fed to the reactor together with an equal volumetric solution of water containing 0.9 wt% of the catalyst H, SO,. The specific reaction rate constant is 0.311 min-1 Activity: a) Determine the necessary CSTR volume if 80% conversion is to be achieved www.utm my innovative entrepreneuria.plobal

Answer 1

Production rate of ethylene glycol = 200 million pounds/year

Molar mass of ethylene glycol (C2H6O2) = 62 lb/lbmol

Production rate of ethylene glycol in lbmol/min

= (200*10^6 lb/yr) x (1yr/525600 min) / (62 lb/lbmol)

Fe = 6.137 lbmol/min

Conversion of ethylene oxide X = 0.8

Molar flow rate of ethylene oxide FA0 = Fe/X

FA0 = (6.137 lbmol/Min) / 0.8

= 7.67 lbmol/Min

Initial concentration of ethylene oxide CA0 = 1 lbmol/ft3

Volumetric flow rate of ethylene oxide vA0 = FA0/CA0

vA0 = (7.67 lbmol/Min) / (1 lbmol/ft3)

= 7.67 ft3/min

Volumetric flow rate of Water vB0 = vA0 = 7.67 ft3/min

Total volumetric flow rate of reactants = vA0 + vB0

v = 7.67 + 7.67 = 15.34 ft3/min

Rate constant k = 0.311 min-1

Design equation of CSTR

V/FA0 = X/(-rA)

V/FA0 = X/(kCA)

V/FA0 = X/[kCA0(1-X)]

V = (v*X) / [k(1-X)]

V = (15.34 ft3/min*0.8) / [0.311 min-1 * (1-0.8)]

Volume of reactor V = 197.31 ft3