Vapor-Liquid Equilibrium using HYSYS

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Vapor / Liquid Equilibrium Using HYSYS
Prepared by A.N.Tabish Lab. Engineer /
Lecturer
Department of Chemical Engineering UET, City
Campus, Lahore
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Example 10.3
For the system methanol (1) / methyl acetate (2)
, the following equations provide a reasonable
correlation for the activity coefficient
Where,
In addition following equations provide vapor
pressures
Where T is in kelvin and the vapor pressure are
in kPa.
J.M.Smith, H.C.Van Ness and M.M.Abott (2005),
Introduction to Chemical Engineering
Thermodynamics, Ed. 7, pp. 359, McGraw Hill
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CALCULATE

1. P and y1, for T 318.15 K and x1 0.25
2. P and x1, for T 318.15 K and y1 0.60
3. T and y1, for P 101.33kPa and x1 0.85
4. T and x1, for P 101.33kPa and y1 0.40

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Solution Strategy

• Start a new case in HYSYS.
• Define components
• Select Thermodynamic model.
• Draw the PFD (material streams)
• Define
• Composition
• Vapor fraction
• Mole/mass flow rate
• Temperature / Pressure
• Determine BUBL/DEW Pressure/Temperature
• Determine composition using K-Value information

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HYSYS
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• Start a new case in HYSYS.
• Define components (Methanol Methyl Acetate).

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• Select NRTL model.

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• Draw the PFD (1 material streams)

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• Vapor Pressure of Methanol

44.51kPa using Antoine Equation

• Vapor Pressure of Methyl Acetate

65.64kPa using Antoine Equation
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BUBL Pressure

1. P and y1, for T 318.15 K and x1 0.25

73.50 kPa in manual calculations
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Vapor compositions
y1 0.282 y2 0.718
y1 0.278 y2 0.722
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DEW Pressure

1. P and x1, for T 318.15 K and y1 0.60

62.89 kPa in manual calculations
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Liquid compositions
x1 0.8169 x2 0.1831
x1 0.8099 x2 0.1901
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BUBL Temperature

1. T and y1, for P 101.33kPa and x1 0.85

331.20K 58 oC in manual calculations
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Vapor compositions
y1 0.670 y2 0.330
y1 0.671 y2 0.329
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DEW Temperature

1. T and x1, for P 101.33kPa and y1 0.40

326.70K 53.7 oC in manual calculations
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Liquid compositions
x1 0.4602 x2 0.5398
x1 0.4517 x2 0.5483
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VLE Plot

• Download registry files from
• http//people.clarkson.edu/wilcox/Design/EqPlots.
  dll
• http//people.clarkson.edu/wilcox/Design/EqPlots.
  edf
• and save them to your computer at some safe
  place.
• Create a case containing the components of
  interest and choose a suitable fluid package. 
• Go to the Simulation Environment
• Go to Tools/Preferences/Extensions and Click on
  Register an Extension. 
• Find EqPlots.dll and open it.  This will remain
  part of HYSYS or UniSim on your machine until it
  is Unregistered. Close Preference.
• Go to Flowsheet/Add Operation.  Select the
  Extensions category and Add Equilibrium Plots. 
  This should open the equilibrium plots extension.
• For a Binary plot, click the Binary tab at the
  bottom of the Equilibrium Plots menu, and select
  the components and the type of plot desired. 
• For an XY plot, specify either T or P, and click
  on Plot. 
• For a TXY plot, specify P.  For a PXY plot,
  specify T.

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Example 10.4

• For a mixture of 10 mol- methane, 20 mol-
  ethane, and 70 mol- propane at 50 (oF),
  determin
• The dew point pressure
• The bubble point pressure

J.M.Smith, H.C.Van Ness and M.M.Abott (2005),
Introduction to Chemical Engineering
Thermodynamics, Ed. 7, pp. 364, McGraw Hill
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Home Work Task

1. Assuming the validity of Raoult's law, do the
   following calculations for the benzene
   (l)/toluene (2) system

1. For the system ethyl ethanoate (1) and n-heptane
   (2) at 343.15 K (70"C)

BUBL P calculation for T 343.15 K (70C), x1
0.05. DEW P calculation for T 343.15 K (70C),
y1 0.05.
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Home Work Task Contd.

• Make the following VLE calculations for the
  methane (l) / ethylene (2) / ethane (3) system