DWSIM/C2/Rigorous-Distillation/English

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Visual Cue Narration
Slide Number 1

Title Slide

Welcome to this tutorial on Simulating a Rigorous Distillation column in DWSIM.
Slide Number 2

Learning Objectives

In this tutorial, we will learn to:
  • Simulate a Rigorous Distillation column
  • Specify column Pressure Profile
  • Specify Tray Efficiencies
  • Check desired product compositions and
  • View the Column profiles
Slide Number 3

System Requirements

This tutorial is recorded using
  • DWSIM 5. 8 (Classic UI) Update 3 and
  • Windows 10 OS.

But, this process is identical in Linux, Mac OS X or FOSSEE OS on ARM.

Slide Number 4

Prerequisites

To practise this tutorial, you should know to-
  • Add components to a flowsheet
  • Select thermodynamic packages
  • Add material and energy streams and specify their properties.
Slide Number 5

Prerequisite Tutorials and Files

https:\\spoken-tutorial.org

The prerequisite tutorials are available on this website.

You can access these tutorials and all the associated files from this site.

Slide Number 6

Code Files

shortcut-end file used in the tutorial is provided as a Code file on this tutorial page.

Download the files from Code Files link.

Switch to DWSIM. I have already opened DWSIM on my machine.
Show DWSIM window


File >> Save As >> rigorous

I have opened the file shortcut-end.dwxmz.

Let me save this as rigorous.

We can see that the file name has changed now to rigorous.

Click on the Settings button Click on the Settings button on the toolbar.
Click on Systems of Units tab. Click on Systems of Units tab.
Pressure → atm


Press Enter.

Locate Pressure menu on the right hand column.

Click and choose atm for atmosphere.

Press Enter.

Delta_Patm

Press Enter.

Similarly, change the units of Delta_P to atm.

Press Enter.

Close the Settings window. Close the Settings window.
Let me switch to the slides.
Slide Number 7

Compounds: Benzene & Toluene

Thermodynamics: Raoult’s Law

Inlet Stream:

Flow Rate: 100 Kmol/h

Pressure: 1 atm

Mole Fractions:

Benzene = 0.4, Toluene = 0.6

Method: Fenske-Underwood-Gilliland

This problem was solved in the spoken tutorial on Shortcut Distillation.
Slide Number 8

Column Properties

Reflux Ratio: 1.4 times minimum reflux ratio.

Product:

Light: Benzene, Heavy: Toluene

Distillate: XD = 0.99

Bottoms: XB = 0.01

These values form the basis for the rigorous distillation column problem.
Slide Number 9

Solution

Minimum reflux ratio = 1.655

Minimum number of stages = 11

Actual number of stages = 20

Optimal feed location = 9

Bottoms product rate=60.204 kmol/h

This represents the solution of the given problem using Shortcut Distillation.

We will be using these values shortly.

Let us begin by replacing the Shortcut column with a Rigorous column.
Let me go back to the simulation.
Shortcut column → Delete Right-click on the Shortcut column, and select delete.

Click Yes in the prompt box.

Click on Columns tab At the bottom of the main simulation window, go to Columns tab.
Click and drag Distillation Column to the flowsheet From the displayed list, drag and drop a Distillation Column to the Flowsheet.
Let’s us now arrange it as required.
Click on the Distillation Column. Click on the Distillation Column.
Cursor to the Property Editor Window On the left, go to the Property Editor Window of the Distillation Column.
Column Specs >> General Now under Column Specs, click on the General tab.
Cursor to Number of Stages option Locate the Number of Stages option.

We have to enter the total number of trays here.

We got the equilibrium stages to be 20 from the shortcut method.
Show slide.

Highlight 20

We can see it in the slide.

Let us go back to DWSIM.

Number of Stages >> 21 This number should be one more than the equilibrium stages given by shortcut method.

So, change the Number of Stages to 21 and press Enter.

Click the Condenser tab to show total condenser. This number includes the condenser also in DWSIM.

So here we will use a total condenser.

Cursor to Solver option Now we will select the solution method.
Solver >> Wang-Henke (Bubble Point) Click on the drop-down against Solver.

Choose the Solver as Wang-Henke (Bubble Point), if not already selected.

By default, Wang-Henke (Bubble Point) is already selected as Solver.

Now we will connect the streams to the Distillation column.
Point to Column Configuration Go to Column Configuration section.
Connections >> Streams Connections >> Feeds Navigate to Connections >> Streams Connections >> Feeds
Point to the Feed Ports

Select Column Feed Port #5

Here we have to specify the stream which is entered as a feed to the column.

Here, we can see the list of Feed Ports.

Select any port where we want the feed to enter the Distillation column.

For a better look, we select Column Feed Port #5.

Click on the down-down against Column Feed Port #5. Click on the down-down against Column Feed Port #5.

Select Feed and press Enter.

In a similar way, we will connect the product streams.
Click on the Products tab. Now, click on the Products tab.
Distillate >> Distillate Select Distillate as Distillate and press Enter.
Bottoms >> Bottoms. Select Bottoms as Bottoms and press Enter.
Now we will connect heat duties to reboiler and condenser.
Click on the Duties tab. Click on the Duties tab.
Select Reboiler Duty as R-Duty. Select Reboiler Duty as R-Duty and press Enter.
Select Condenser Duty as C-Duty. Select Condenser Duty as C-Duty and press Enter.
Connections >> Stream-Stage Associations Now under Connections, click on Stream-Stage Associations tab.
Feed >> Stage location >> Stage6.

Press Enter.

For Feed Port type, select Stage location as Stage9.

Press Enter.

This is as per the solution we got in the Shortcut Distillation column.

We got the Optimal Feed Location to be 9 from the Shortcut method.

Show slide.

Highlight:Optimal feed location = 9

We can see it in the slide.

Let us go back to DWSIM.

This completes the connections.
Now we have to provide the top and bottom specifications.
Cursor to Column Specs Under Properties tab, locate the section Column Specs.
Click on the Condenser tab.

Select Condenser Type as Total


Click on the Condenser tab.

Select Condenser Type as Total, if not already selected.

By default, it is total condenser.

We will leave it as it is.

Condenser Pressure >> 1 atm Change Condenser Pressure to 1 atm and press Enter.
Condenser Pressure drop >> 0. Select Condenser Pressure drop as 0.

By default, it is 0.

We will leave it as it is.

Specification >> Reflux Ratio Next select the Specification as Reflux Ratio, if not already selected.

By default, Reflux Ratio is already selected as Specification.

Reflux Ratio >> 2.317 Under Compound, we can see a field.

Here we can enter the value of reflux ratio.

We will enter the Reflux Ratio as 2.317.

Press Enter.

Click on Reboiler tab

Reboiler Pressure >> 1.1 atm

Now click on Reboiler tab.

Change Reboiler Pressure to 1.1 atm and press Enter.

Specification >> Product Molar Flow

Molar flow rate >> 60.204

Highlight 60.204 in the slide

Select Specification as Product Molar Flow, if not already selected.

Under Compound, change the units to kmol/h and press Enter.

Now enter the Molar flow rate as 60.204.

Press Enter.

This is suggested by the shortcut solution.

We can see it in the slide.

Let us go back to DWSIM.
Now we will also see how to specify the pressure for the intermediate stages.
Point to Column Configuration section Now go to Column Configuration section.
Click on Stages tab. Click on Stages tab.
Cursor to the Condenser and Reboiler value(drag to see Reboiler)

Point to the zero assigned Pressure

It shows the condenser and reboiler pressures as 1 and 1.1 atmosphere.

New stages that have been added, are assigned zero pressure, which is incorrect.

We would like the intermediate stage pressures to take the interpolated values.

Click on the Estimate Stage Pressures by Interpolation

Point to the Pressure values

Cursor to the Efficiency column

Under Column Configuration section, go to the extreme left.

Here we can see 5 different icons.

Hover the mouse to the last icon.

A popup is displayed as Estimate Stage Pressures by Interpolation.

Click on the icon.

Immediately, linearly interpolated values are assigned to every stage.

We can also edit the pressure of the individual stages, if they are known.

We may also change the efficiency in one or more stages.

Now we will run the simulation.
Click on Solve Flowsheet button Click on Solve Flowsheet button on the toolbar.
When the calculations are completed, click on the Distillation column.
Cursor to the Distillation column

Cursor to the Results

Condenser Duty = 1130.51 kW

Reboiler Duty = -1161.91 kW

Go to the Property Editor Window of the Distillation Column.

Locate the Results section.

This shows all the required results like

  • Condenser Duty
  • Reboiler Duty and
  • Column Profiles
Cursor to Column profiles Now let us look at the Column profiles.
Click on View Temperature, Pressure and Composition Profiles button. Click on View Temperature, Pressure and Composition Profiles button.
Point to the Column profiles

Click on the Table tab

Now we can see a pop-up window.

Here, we can see the -

  • Temperature profiles
  • Flows profiles
  • Component flows and
  • Component fractions

For the exact numbers, click on the Table tab to the right of the Graph tab.

Press CTRL+S Now save this file.
Slides Let us summarize
Slide Number 10

Summary

In this tutorial, we have learnt to:
  • Simulate a Rigorous Distillation column
  • Specify column Pressure Profile
  • Specify Tray Efficiencies
  • Check desired product compositions and
  • View the Column profiles
Slide Number 11

Compounds: Ethanol & Water

Thermodynamics: Raoult’s Law

Inlet Stream:

Flow Rate: 100 kmol/h

Pressure: 1 atm

Mole Fractions:

Ethanol = 0.5, Water = 0.5

Take the Assignment from the Shortcut Distillation column.


Perform the simulation using Rigorous Distillation.


Here is the assignment problem statement of the Shortcut Column.

Slide Number 12

Column Properties

Reflux Ratio: 1.5 times the minimum reflux ratio.

Product:

Light: Ethanol, Heavy: Water

Distillate: XD = 0.99

Bottoms: XB = 0.01

With this, we have come to the end of this tutorial.
Slide Number 13

About the Spoken Tutorial Project


Watch the video available at the following link.

http://spoken-tutorial.org/

It summarizes the Spoken Tutorial project.

Slide Number 14

Spoken Tutorial Workshops

The Spoken Tutorial Project Team
  • Conducts workshops and
  • Gives certificates.
  • For more details, please write to us.
Slide Number 15

Forum Slide

Do you have questions in this Spoken Tutorial?

Please visit this site

Choose the minute and second where you have the question.

Explain your question briefly.

Someone from the FOSSEE team will answer them.

Please post your time queries in this forum.
Slide Number 16

DWSIM Flowsheeting Project

The FOSSEE team coordinates conversion of existing flowsheets into DWSIM.

We give honorarium and certificates for those who do this.

For more details, please visit this site.

Slide Number 17


Lab Migration Project

The FOSSEE team helps migrate commercial simulator labs to DWSIM.

We give honorarium and certificates for those who do this.

For more details, please visit this site

Slide Number 18


Acknowledgements

Spoken Tutorial and FOSSEE projects are funded by NMEICT, MHRD, Government of India.
Slide Number 19


Thanks

This tutorial was originally recorded by Prof Kannan Moudgalya in September 2015.

This is Kaushik Datta from IIT Bombay.

Thanks for joining.

Contributors and Content Editors

Kaushik Datta