Separation Trains Azeotropes

1
Separation TrainsAzeotropes

• Chapt. 7

2
A Word About Column Pressure

• Cooling Water Available at 90ºF
• Distillate Can be cooled to 120ºF min.
• Calculate the Bubble Pt. Pressure of Distillate
  Composition at 120ºF
• equals Distillate Pressure
• Bottoms Pressure Distillate Pressure 10 psia
  delta P
• P gt Atm, Pressure generated by system.
• For Vacuum, how is it that generated?

3
Vapor Pressure vs Temp
120F
4
Steam Ejector Generates the Vacuum.
High Pressure High Velocity Steam
Velocity gt Mach 1
Bernoullis Equation
Vacuum
5
Binary DistillationIPA/IPE
x
x
x
6
Azeotrope Conditions

• Conditions on the Activity Coefficient
• Minimum Boiling, ?jLgt 1
• Maximum Boiling, ?jLlt 1
• xjyj, j,1,2,C

7
Raoults Law
8
Importance of Physical Property Data Set

• In all cases
• Need sophisticated liquid phase model to
  accurately predict the activity coefficient for
  the liquid.
• For High Pressure Cases Only
• Also need sophisticated (non-ideal) gas phase
  fugacity model

9
Two Type of Min. Boiling Azeotropes

• Homogeneous Azeotrope

• Heterogeneous Azeotrope

Overlay with Liquid/Liquid Separation
10
Multi-component Azeotropes

• Residue Curve Map
• dxj /dt dxj /d ln(L) xj yj
• Integrate from various starting points

11
Defining Conditions for Multi-component Azeotrope
t goes from 0 to 1, ideal to non-ideal to find
Azeotrope
12
(No Transcript)
13
Distillation Boundaries

• Equilibrium Trays in Total Reflux
• Distillation Lines
• Tangent to Residue Curve

14
Distillation

• XB, XF and YD form a line for a Distillation
  Column
• Line can not cross Azeotrope line

15
Ethanol/Water Distillation with Toluene to Break
Azeotrope
16
Ethanol/Water Distillation with BenzeneTo Break
Azeotrope
17
Pressure Swing to Break Azeotrope
Temp. of Azeotrope vs. Pressure
Mole Fraction of Azeotrope
18
To Create Residue Maps

• After putting in the components and physical
  property method
• Choose
• Tools/Analysis/Property/Residue