Simulation of a Steady-State Binary Distillation Column

reflux ratio

3

reboil ratio

2.5

Ponchon-Savarit diagram

composition profile

temperature profile

molar flow rates

Consider an ideal equimolar binary mixture of benzene and toluene at

760mmHg

. This mixture, with a thermal quality equal to 0.5, is fed to a 10-stage column with a total condenser and partial reboiler. The feed stage is stage 7. The feed flow rate is taken equal to

10kmol/hr

. You can set the values of the reflux ratio

R

and reboil ratio

s

. This Demonstration computes the temperature and composition profiles using a rigorous approach, which includes both energy and mass balances. It is clear that the numerical simulation gives data similar to the graphical method developed by Ponchon–Savarit. The molar flow rate profiles for both the liquid and vapor phases are also displayed. A separate calculation showed that, for

R=3

and

s=2.5

, stage 7 is the optimal feed location. Indeed, if one changes the feed location while keeping the same values for

R

and

s

, the cooling and heating duties will be higher. The simulation finds cooling and heating duties equal to

Qc=-592708kJ/hr

and

Qr=435526kJ/hr

, respectively, for

R=3

and

s=2.5

. All results found in this Demonstration show perfect agreement with those given by HYSYS (http://www.aspentech.com/hysys/).