Presentation outline
Objectives
Importance
Applications
Vapor-Liquid Equilibrium Concept
Theory included
Equilibrium data interpretation
Vapour liquid equilibrium
2
Presentation outline (Cont’d)
Experimental setup
Experimental results
Graphical representations
Discussion
Conclusion
3
Vapour liquid equilibrium
Objectives
To produce vapor-liquid equilibrium at atmospheric
pressure
To determine the equilibrium temperature and
compositions for a certain system
To compare the experimental results with the
theoretical data supplied
4
Vapour liquid equilibrium
Importance
A knowledge of the vapor-liquid equilibrium is essential in the analytical treatment of a distillation problem
Azeotropic systems can be identified
Vapour liquid equilibrium
5
Applications
• Industrial Separation Processes
• Distillation of Crude Oil
• Distillation of Alcohols
• Design of Distillation Columns
6
Vapour liquid equilibrium
Vapor-Liquid Equilibrium Concept
An isolated system consisting ofliquid and vapor phases in intimatecontact wherein
• The temperature, pressure & phase compositions reach final values
• The vaporization occurs at the same rate as the condensation
7
Vapour liquid equilibrium
Theory included
At equilibrium condition,T liquid = T vapor
P liquid = P vapor
Chemical Potential liquid = Chemical Potential vapor
No change in composition
8
Vapour liquid equilibrium
Equilibrium data interpretation
Gibb’s phase rule gives
F = C-P+2
For two component VLE, F=2-2+2=2
Thus by fixing any two of the three intensive variables will
automatically fix the remaining one.
Binary VLE data can be graphically represented in several
ways,
9
Vapour liquid equilibrium
Experimental setup11
water out
water outwater in
water in
Vapour liquid equilibrium
cotton
condenser
stand
thermometer
insulationglass biddistillate collector
liquid phase separatorheater
ethanol water solutionround bottom flaskrecycle line
Experimental results
Equilibrium temperature = 80 oC
Equilibrium composition,
Liquid phase, x = 24 % mole ethanol
Vapor phase, y = 48 % mole ethanol
12
Vapour liquid equilibrium
Discussion
• Sample had been taken from the system
• High volatility of ethanol
• Approximate readings of refractive index
• Supplied Refractive Index Vs. Composition curve at 300C
• Pressure could not be maintained constant
15
Vapour liquid equilibrium
Conclusion
Temperature, pressure and composition of two phases does not change at equilibrium
The temperature and pressure of the liquid and vapor phases are equal but the compositions are not at equilibrium
The knowledge acquired from this experiment can be used for further calculations
16
Vapour liquid equilibrium