Distillation for Chemical Engineers

1. Distillation
-Akul Jain

2. Contents:
 VLE
 Basic terms
 Flash Distillation
 Steam Distillation
 Batch Distillation
 Multistage fractionation of binary mixtures
 McCabe Thiele Method
 Ponchon Savarit
 Azeotropic Distillation
 Extractive Distillation
 Reactive Distillation
 Conclusion

3. Vapour Liquid Equilibrium :
Constant T vapour liquid
equilibria
Constant P vapour liquid equilibria
Raoult’s law:
For ideal is = 1.
•(+) ve deviation >1
•(-) ve deviation <1
•Azeotropes

4. Basic Terms:
Distillation Column Terms:
 Relative volatility
 Condenser
 Reboiler
 Distillate
 Bottom
 Feed
 Liquid Reflux
 Rectifying section
 Stripping section

5. Flash Distillation
At steady state :
Enthalpy –
concentration and
equi. Dia.

6. Steam Distillation :
The property of an immiscible liquid mixture
forms the basis of steam distillation.
Case 1 – Substance A is immiscible with water and
feed contains A and some traces of non volatile
impurities .
If system is not at equilibrium than
E – Vaporizing
efficiency
Case 2 – The feed is a mixture of A and C ; C is an essentially non volatile
substance, A and C form an ideal solution and are immiscible with water.
;

7. Batch Distillation :

8. Continuous Multistage fractionation of
binary mixtures :
For 1
For 2
For 3
For 4

9. McCabe Thiele Method
Rectifying section
:
Stripping section :
Feed line :

10. Total reflux :
No of stages :
Fenske’s equation
Minimum reflux ratio :

11. Ponchon Savarit :
Rectifying section : Stripping section :

12. Azeotropic distillation :
Azeotropic distillation of acetic acid
water with butyl acetate.
 Here butyl acetate is
entrainer.

13. Extractive Distillation :

14. Reactive Distillation

15. Advantages of RD :
1. Single column replaces one reactor and 3 distillation
columns which is process integration.
2. Less material is required for the construction of just single
column hence RD is much more cheap. Statistically, RD
reduces about 50% of the cost as compared to conventional
process.
3. Low energy consumption.
4. Lower operating cost .
Disadvantages of RD :
1. Degree of freedom is 3 for RD but for conventional process
it is 9. Hence conventional process gives us more variables
than RD.
2. Above mentioned volatility problem is also a disadvantage.
It limits it to very few reactions.
3. In some processes the optimum conditions of temperature
and pressure for distillation may be far from optimal for
reaction and vice versa.

16. Conclusion:
There are many methods to separate
various mixtures . Maximizing the
product by using minimum amount of
investment is our final aim.

17. Thank you