Process design of distillation column

Diagram

Feed

Distillate

Bottom

Cumene 0.996Phenol 0.004

Xd

Cumene 0.0016Phenol 0.9984

Xb

Cumene 0.17Phenol 0.83

Xf

Feed composition

Feed stream composition

Feed Mass(Kg/hr)

Phenol 277.452

Cumene 66.972

AMS 4.381

Cont…

Since the amount of AMS in feed stream is negligible and its properties resembling close to cumene. Hence it can be merged with cumene for easier calculations.

Feed Mass(Kg/hr) Mass(Kgmol/hr)

Xf

Phenol 277.452 2.948 0.83

Cumene 71.353 0.594 0.17

Calculation for bottom temperature

Bottom pressure = 1.28 atm = 972.8 mmHg

Using Antoine equation

Antoine equation constants for phenol

A = 16.4279B = 3490.89C = -98.59

Cont…

Putting the constants in above equation

The top temperature as given in process conditions is

Taking avg temperature

Now taking the average of these temperatures

Calculating vapour pressure of cumene Using antoine equation

Here = 171.86

The following are the antoine constants for cumene

A = 13.957B = 3363.3C = 207.78

Cont…

Putting the values in eq above

Calculating vapour pressure of phenol Using antoine equation

Here = 171.86

The following are the antoine constants for phenol

A = 14.4387B = 3507.80C = 175.4

Cont…

Putting the values in eq above

Calculating relative volatility

Putting the corresponding values of pressure in above eq

The following corresponding vapor-liquid relation is obtained

X .002 .02 .10 .20 .30 .40 .50 .60 .70 .80 .90 1.0

Y .004 .043 .19 .35 .49 .60 .69 .77 .84 .90 .95 1.0

VLE diagram Since the feed is entering at its boiling point hence q-line is vertical

0 0.2 0.4 0.6 0.8 1 1.20

0.2

0.4

0.6

0.8

1

1.2

VLE Diagram

Calculating minimum reflux ratio

So from graph Φm = 0.165

Calculating maximum reflux ratio

Taking

Calculating the number of theoretical and real plates required

Here obtained from the graph

Assuming efficiency = 75%

Calculating flooding velocityAt top plate

At bottom plate

Density at top

Cont…Density at bottom

Surface tension Top Cumene = 29.01 mN/m Bottom Phenol = 37.66 mN/m

Top = 0.05880 Bottom = 0.0849 Tray spacing = 0.30m

Figure

Cont…So from the previous figure Top Bottom Surface tension correction Top Bottom Flooding velocity Top Bottom

Cont… Design for 85% flooding velocity at max flow rate Top Bottom

Max vol.flowrate of vapour Top Bottom Net area required Top Bottom N

Calculating column area and diameter Downcomer area = 12% of column area

Top Bottom Column diameter Top Bottom