Design of Distillation Column

Azeotropic distillation of ethanol-water mixture is accomplished by adding a volatile third

component to the liquid which changes the volatility of one of the two components more than the

other so the components are separated by distillation. The two components to be separated often

have similar boiling point components which do or do not azeotrope in the binary mixture, but

sometimes there are components which do azeotrope despite having vastly different boiling points.

It is likely that in some cases, one system can be separated either by

azeotropic distillation or by extractive distillation, for instance , alcohol/water, acid/water, etc.

The added third component, sometimes called the entrainer, may form a ternary azeotrope with

the two components being separated. However, it must be sufficiently volatile from the solution so

that it is taken overhead with one of the two components in the azeotropic distillation column

Contents 

1  Introduction ................................................................................................................................ 4 

Distillation Column Design.................................................................................................................. 4 

2  Feed Data Base ............................................................................................................................ 5 

Mole Fraction ..................................................................................................................................... 5 

Average Molecular Weight ................................................................................................................. 6 

Mass Balance ...................................................................................................................................... 6 

3  Minimum Reflux Ratio ............................................................................................................... 7 

4  Different R .................................................................................................................................... 8 

R=1.3Rmin .......................................................................................................................................... 8 

R=1.5Rmin .......................................................................................................................................... 8 

R=1.7Rmin .......................................................................................................................................... 9 

5  Temperatures and concentration of vapour ....................................................................... 10 

6  Diameter..................................................................................................................................... 11 

Top diameter .................................................................................................................................... 12 

Bottom diameter .............................................................................................................................. 13 

7  Heat loss ..................................................................................................................................... 14 

Heat loss without the insulation ....................................................................................................... 15 

Insulation .......................................................................................................................................... 16 

75 mm insulation ........................................................................................................................ 16 

50 mm insulation ........................................................................................................................ 16 

25 mm insulation ........................................................................................................................ 17 

8  Condenser .................................................................................................................................. 17 

Latent heats ...................................................................................................................................... 17 

Vapour mass flow rate in the top ..................................................................................................... 18 

Heat Transfer .................................................................................................................................... 18 

hi at 30℃ .......................................................................................................................................... 18 

Overall heat transfer coefficient ....................................................................................................... 19 

Area .................................................................................................................................................. 19 

Number of pipes ............................................................................................................................... 20 

Cross sectional area .......................................................................................................................... 20 

Velocity ............................................................................................................................................. 20 

hiat 30℃ .......................................................................................................................................... 20 

Actual overall heat transfer coefficient ............................................................................................ 21 

Actual Area ....................................................................................................................................... 21 

Actual Number of pipes .................................................................................................................... 21 

Actual Cross sectional area ............................................................................................................... 21 

Actual velocity .................................................................................................................................. 22 

Pitch ................................................................................................................................................. 22