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INPUT   DATA

♥ EXAMPLE Of Input/Output

Title

Component	Component Name	Feed	Equilibrium Constant
#		Mols
1
2
3
4
5
6
7
8
9
10
11
12

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OUTPUT   VARIABLES   &   GRAPHS

Component	K-Value	Feed	Feed	Liquid	Liquid	Vapor	Vapor
		Mols	Mol. fraction	Mols	Mol. fraction	Mols	Mol. fraction
1
2
3
:
11
12
Totals

Liquid-Vapor Equilibrium

Equilibrium stage operations are based on principles of phase equilibrium. When two phases are mixed together, some of the components will partition between the phases as the system tries to reach equilibrium. When the phases are separated, one is enriched with the solute and the other depleted. This combination of mixing, approach to equilibrium, and separation is called an equilibrium stage. The basic calculation for an equilibrium stage is the flash calculation. A single equilibrium stage can be used to make a separation. Many separation processes (distillation, extraction, leaching, etc.) are based upon cascades of equilibrium stages.

The following equations are used for the multicomponent flash calculations. The main equality equation requires a trial-and-error solution, after first ascertaining that the flashed mixture is not all liquid or all vapor. The value of m_L which causes the summation to equal 1.0 is the correct value of m_L. The implementation here uses the iterative convergence method of Kostecke and can handle a mixture containing up to 12 components.

where
     K_i = equilibrium ratio for each component in feed stream for the given temperature and pressure
     m_i = mole fraction of component for each component in feed
     m_L = total moles of liquid in equilibrium
     n = number of components in feed

BIBLIOGRAPHY

• Coker, AK; Fortran Programs For Chemical Process Design, Analysis & Simulation; Gulf Publ. Co, Houston, 1995.
• McCain,Jr WD; The Properties Of Petroleum Fluids; PennWells Books, Tulsa, Okl., USA, 1990.
• Chopey, NP; Handbook of Chemical Engineering Calculations; McGraw Hill, New York, 2003.