Calculating K Values (VLE Coefficients)

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SUMMARY

This discussion focuses on calculating vapor-liquid-equilibrium (VLE) coefficients, specifically K-values, for a multicomponent distillation process involving exotic chemicals under vacuum conditions (13 kPa and 60°C). The user plans to utilize the Antoine Equation (ln P = A - (B / (T + C)) from Coulson & Richardson, Volume 6) to determine the saturated vapor pressure (P(i)sat) of each component. The K-values will be calculated using Raoult's Law, expressed as y(i)P = x(i)P(i)sat. The user confirms that the pressure obtained from the Antoine equation will indeed represent the saturated vapor pressure needed for these calculations.

PREREQUISITES
  • Understanding of vapor-liquid equilibrium (VLE) concepts
  • Familiarity with Raoult's Law and its mathematical formulation
  • Knowledge of the Antoine Equation for calculating vapor pressures
  • Basic principles of multicomponent distillation
NEXT STEPS
  • Study the Antoine Equation in detail, including its various forms and applications
  • Research advanced applications of Raoult's Law in non-ideal systems
  • Explore fugacity coefficients and their role in VLE calculations
  • Learn about multicomponent distillation techniques and their optimization
USEFUL FOR

Chemical engineers, process engineers, and students involved in distillation processes or vapor-liquid equilibrium analysis will benefit from this discussion.

_Greg_
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Right so basically, I'm doing a multicomponent distillation with some exotic chemicals.
My feed comes in at 13kPa and 60*C, so it's under vaccum. This will be a two phase mixture.
What I need is the vapour-liquid-equilibrium coefficients, 'K- values' at feed conditions.
I'm basing this on an ideal system to start with then I'll do it as non-ideal (fugacity coefficients etc)

So for now, I'm planning on using the Antoine Equation ln P = A - ( B /( T + C) ) (from coulson & richardson vol 6)
Now the K values can be calulated with Raoults law Ki = Pi(sat)/Pt
My question is, will the pressure value I get from the Antoine equation be the saturated vapour pressure of component i? (Pi(sat))

Sorry this probably sounds terrible, but it's been a while
 
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From google:

Mathematically, Raoult’s law is expressed as

y(i)P = x(i)P(i)sat for all species (i= 1, 2,...,N)

where xi is the liquid phase mole fraction, yi is the vapor phase mole fraction, P(i)sat is the vapor pressure of pure component i, and P is the total pressure. In words, Raoult’s law says that the partial pressure of each species in the vapor phase is equal to its mole fraction in the liquid phase times its pure-component vapor pressure.

And P(i)sat you can calculate with the Antoine equation at a given temperature, so you're right
 
Thanks Vulgar
Just wasn't sure because there's different forms of the antoine equation, some say Psat, other just say P. Could have done this like 2 years ago, now in my final year I struggle with some of the basics lol.
Cheers for clearing that up ;)
 

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