### Distillation Theory

```Distillation Theory
Team 3: Robert Clifford, Patricia Firmin,
Gen Liang, Rooma Raza
The Basics of Distillation
Different Parts of Distillation
Condenser
Rectifying Section
Stripping Section
Reflux
Reboiler
Bottoms Product
Possible Feed Conditions
L-L
q=
F
V -V
q = 1+
F
McCabe-Thiele Graphical Method
Minimum Reflux Ratio
Optimal Feed Stage
Shortcut Method
• Fenske equation-minimum number of trays and split fraction
x lk (1 - x hk )
ln
x hk (1 - x lk )
Nm =
ln a lk /hk
N
a k x hk
xk =
N
1 + (a k -1)x hk
m
m
Tray Number and Reflux Ratio
blk = x lk
Ni =
{(a lk /hk
b hk = 1- x lk
12.3
-1)2/3 (1 - bi )1/6 }
N T = g N max i (N i ) + (1- g N ) min i (N i )
Ri =
{(a lk /hk
1.38
-1)0.9 (1 - bi )0.1 }
R = g R max i (Ri ) + (1 - g R ) min i (Ri )
Stage Efficiency
E0 = 13.3- 66.8log m
• Range from 41% to 88%
• For close-boiling mixtures, liquid viscosity is low, resulting in
high stage efficiency
Distillation Column Sizing
• Calculate column Diameter by Internal flowrates and design column
at 80% of linear flooding velocity.
A = p D 2 = V '/ (0.8Unf er g )
Unf = Csb (( rl - r g ) / r g ) (20 / s )
0.5
• If D> 3m = Parallel columns
0.2
Types of Distillation Columns
• Packed Bed Columns
 Used more often for absorption and
distillation of vapor-liquid mixtures.
 The liquid flows downward through the packing and
the vapor flows upward through the column.
 Cost efficient
 Lower pressure drop
 Good for thermally sensitive liquids
 Packing can break during installation
Types of Distillation Columns
• Tray Column
 The number of trays or stages is dependent
 Cost efficient
 Can handle high liquid flow rates
 Higher pressure drops than packed columns
 Foaming can occur due to agitation
Extractive Distillation
Reactive Distillation
Vacuum Distillation
References
• Seader, J. D., Ernest J. Henley, and D. Keith. Roper. Separation Process
Principles: Chemical and Biochemical Operations. 3rd ed. Hoboken, NJ:
Wiley, 2011. Print.
• "ENCYCLOPEDIA OF CHEMICAL ENGINEERING EQUIPMENT." Distillation
Columns. N.p., n.d. Web. 11 Feb. 2015.
http://encyclopedia.che.engin.umich.edu/Pages/SeparationsChemical/Distill
ationColumns/DistillationColumns.html.
• Biegler, L., Grossmann, I., Westerberg , A., 1997, Systematic Methods of
Chemical Process Design, Prentice Hall.
• Bravo, Jose L. and James K. Fair. "Distillation Columns." Chemical
Engineering Progress January 1990: 19-29.
```