vapor liquid equilibrium using hysys

August 25, 2010 1

Vapor / Liquid Equilibrium Using HYSYS

Prepared by:

A.N.Tabish

Lab. Engineer / Lecturer

Department of Chemical Engineering

UET, City Campus, Lahore

sat

iiiii PxPy

tabish288@yahoo.com

2

For the system methanol (1) / methyl acetate (2) , the following

equations provide a reasonable correlation for the activity coefficient

Example # 10.3:*

* J.M.Smith, H.C.Van Ness and M.M.Abott (2005), “Introduction to Chemical

Engineering Thermodynamics”, Ed. 7, pp. 359, McGraw Hill

2

21 Axn l2

12 Axn l

TA 00523.0771.2 Where,

In addition following equations provide vapor pressures:

424.33

31.364359158.161

TnP

satl

424.53

51.266525326.142

TnP

satl

Where T is in kelvin and the vapor pressure are in kPa.

August 25, 2010 tabish288@yahoo.com

August 25, 2010 3

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

tabish288@yahoo.com

August 25, 2010 4

Solution Strategy:

Start a new case in HYSYS.

Define components

Select Thermodynamic model.

Draw the PFD (material streams)

Define

1. Composition

2. Vapor fraction

3. Mole/mass flow rate

4. Temperature / Pressure

Determine BUBL/DEW Pressure/Temperature

Determine composition using K-Value information

tabish288@yahoo.com

August 25, 2010 5

HYSYS:

tabish288@yahoo.com

August 25, 2010 6

Start a new case in HYSYS.

Define components (Methanol + Methyl Acetate).

tabish288@yahoo.com

August 25, 2010 7

Select NRTL model.

tabish288@yahoo.com

August 25, 2010 8

Draw the PFD (1 material streams)

tabish288@yahoo.com

August 25, 2010 9

Vapor Pressure of Methanol

Vapor Pressure of Methyl Acetate

44.51kPa using

Antoine Equation

65.64kPa using

Antoine Equation

tabish288@yahoo.com

August 25, 2010 10

BUBL Pressure:

73.50 kPa in manual

calculations

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

tabish288@yahoo.com

August 25, 2010 11

Vapor compositions:

y1 = 0.282

y2 = 0.718

y1 = 0.278

y2 = 0.722i

ii

x

yK

tabish288@yahoo.com

August 25, 2010 12

DEW Pressure:2. P and {x1}, for T = 318.15 K and {y1}= 0.60

62.89 kPa in manual

calculations

tabish288@yahoo.com

August 25, 2010 13

Liquid compositions:

x1 = 0.8169

x2 = 0.1831

x1 = 0.8099

x2 = 0.1901i

ii

x

yK

tabish288@yahoo.com

August 25, 2010 14

3. T and {y1}, for P = 101.33kPa and {x1}= 0.85

BUBL Temperature:

331.20K = 58 oC in

manual calculations

tabish288@yahoo.com

August 25, 2010 15

Vapor compositions:

y1 = 0.670

y2 = 0.330

y1 = 0.671

y2 = 0.329i

ii

x

yK

tabish288@yahoo.com

August 25, 2010 16

4. T and {x1}, for P = 101.33kPa and {y1}= 0.40

DEW Temperature:

326.70K = 53.7 oC in

manual calculationstabish288@yahoo.com

August 25, 2010 17

Liquid compositions:

x1 = 0.4602

x2 = 0.5398

x1 = 0.4517

x2 = 0.5483i

ii

x

yK

tabish288@yahoo.com

August 25, 2010 18

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.

tabish288@yahoo.com

August 25, 2010 19tabish288@yahoo.com

August 25, 2010 20tabish288@yahoo.com

August 25, 2010 21tabish288@yahoo.com

August 25, 2010 22

Example # 10.4:*

* J.M.Smith, H.C.Van Ness and M.M.Abott (2005), “Introduction to Chemical

Engineering Thermodynamics”, Ed. 7, pp. 364, McGraw Hill

For a mixture of 10 mol-% methane, 20 mol-% ethane, and 70 mol-%

propane at 50 (oF), determin:

1. The dew point pressure

2. The bubble point pressure

tabish288@yahoo.com

August 25, 2010 23

Home Work Task:

1. Assuming the validity of Raoult's law, do the following calculations

for the benzene (l)/toluene (2) system:

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

(70"C)

BUBL P calculation for T = 343.15 K (70°C), x1 = 0.05.

DEW P calculation for T = 343.15 K (70°C), y1 = 0.05.

tabish288@yahoo.com

August 25, 2010 24

Home Work Task Contd….

3. Make the following VLE calculations for the methane (l) / ethylene (2) /

ethane (3) system:

tabish288@yahoo.com