DWSIM/C2/Sensitivity-Analysis-and-Adjust/English-timed

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Time Narration
00:01 Welcome to this tutorial on Sensitivity Analysis and Adjust in DWSIM.
00:08 In this tutorial, we will learn to:
00:11 Determine the exact Reflux Ratio for a separation
00:15 Perform Sensitivity Analysis and Adjust operation
00:19 This tutorial is recorded using,

DWSIM 5. 8 (Classic UI) Update 3and Windows 10 OS

00:30 But, this process is identical in Linux, Mac OS X or FOSSEE OS on ARM.
00:38 To practise this tutorial you should know to -

Open a simulation file in DWSIM

00:45 Carry out rigorous distillation simulation
00:48 Add components to a flowsheet
00:51 The prerequisite tutorials are available on this website.
00:55 You can access these tutorials and all the associated files from this site.
01:01 rigorous.dwxmz file used in the tutorial is provided as a Code file on this tutorial page.
01:09 Download the file from the Code Files link.
01:13 This slide shows the problem solved using Rigorous Distillation.
01:18 The purity achieved was less than what was desired.
01:23 To improve the purity, we need to increase the reflux ratio.
01:28 I have already opened DWSIM on my machine.
01:32 Open the file rigorous dot dwxmz.
01:38 Click on Distillate in the flowsheet.
01:41 Go to Property Editor Window.
01:44 Under Input Data, click on Compound Amounts tab.
01:48 Here the Benzene mole fraction is 0.988.
01:53 We would like to increase this to 0.99.
01:57 Let us attempt this by increasing the reflux ratio.
02:01 To do so, click on Optimization option on the menu bar.
02:07 Now click on Sensitivity Analysis option.

Sensitivity Analysis tab opens.

02:14 Here we can see five menus in the menu bar of Sensitivity Analysis.
02:20 Now click on Sensitivity Studies, if not already selected.

On my system, by default, it is already selected.

02:30 Under Case Manager, we can see four buttons.
02:34 Click on New button.
02:36 This will help in creating a new Sensitivity Analysis case.
02:41 We see the name SACase0.
02:45 Here we want to increase the reflux ratio so as to get better purity.
02:50 Thus, reflux ratio is the independent variable.
02:54 Let us do this through the Independent Variables.
02:58 Under Sensitivity Analysis, click on Independent Variables tab.
03:04 Under Independent Variable 1, click on the drop-down against Object.
03:10 Select DC-005, the name of our distillation column.
03:16 On the right hand side, click on the drop-down against Property.
03:22 Now scroll down and select Condenser Specification Value.
03:28 It plays the role of the reflux ratio.
03:31 Recall that we want our reflux ratio to be greater than 2.317.
03:38 So, we will enter the Lower limit as 2.317
03:43 Change the Upper limit to 2.5
03:47 Change the Number of Points to 6
03:51 Now under Sensitivity Analysis, click on Dependent Variables tab.
03:57 On the left hand side, we can see a column named Variables.
04:03 Below that, locate a green coloured plus button to Add new variables.
04:09 Click on it. A new row appears.
04:12 Click on the drop-down against Object.

Select Distillate.

04:20 Now click on the drop-down against Property.
04:25 Scroll down and select Molar Fraction (Mixture) – Benzene.
04:32 Next click on the Results tab to the right of the Dependent Variables tab.
04:38 Then click on Start Sensitivity Analysis button.
04:42 We see the column getting simulated for reflux ratios, one by one.
04:47 At the end of the simulation, we get the message Done.
04:52 Here we can see results for six reflux ratios, from 2.317 to 2.5
05:00 We also see the corresponding benzene compositions.
05:05 Now under Sensitivity Analysis, click on Independent Variables tab.

Change the Number of Points to 11.

05:15 Again click on Results tab.
05:18 Click on Start Sensitivity Analysis button once again.
05:22 You can see that simulation runs to show eleven results this time.
05:28 We can see that the desired purity of 0.99 will be achieved between 2.3719 and 2.3902
05:37 Choose these as the lower and upper limits in Independent Variables.
05:43 Again click on Results tab.
05:46 Click on Start Sensitivity Analysis button once again.
05:51 Here we get the reflux ratio value as 2.382.
05:56 This way we can determine the exact reflux ratio required for 0.99 purity.
06:03 We can also see these results in a graphical form.

Now under Sensitivity Analysis, click on Chart tab.

06:13 On the left of the window, click on the Draw button.
06:17 On the right, we can see the chart here.
06:21 This graph plots between Distillate composition vs condenser specification value.

That is, the reflux ratio.

06:30 Let me save this simulation as sensitivity.
06:37 Now close the Sensitivity Analysis tab..
06:42 We have learnt to calculate the desired reflux ratio by trial and error method.
06;46 DWSIM has a powerful method to directly calculate the reflux ratio.

It is called Adjust.

06:55 Now at the bottom of the main simulation window, click on Logical Ops tab.
07:01 Click on Controller Block.

Drag and drop it outside the column, below the distillate. Now, click on it.

07:11 On the left, we can see a tab displaying properties related to Adjust.
07:17 Under Linked Objects, click on the drop-down against Manipulated Object.

Now select DC-005.

07:28 Next, click on the drop-down against Manipulated Property.
07:34 Then select Condenser Specification Value.
07:38 Next, click on the drop-down against Controlled Object and select Distillate.
07:46 Next, click on the drop-down against Controlled Property.

And select Molar Fraction(Mixture) / Benzene.

07:57 Now, go to Parameters.
08:00 Enter Set-Point/Offset (Controlled Property) as 0.9901 and press Enter.
08:09 I shall enter a slightly larger number 0.9901.
08:14 I want you to think about why I have entered a slightly larger number.
08:19 Now, select the check-box against Solve Globally.
08:24 Then we will run the simulation.
08:27 So, from the toolbar, click on Solve Flowsheet button.
08:31 Let us check the distillate purity.

Click on Distillate in the flowsheet.

08:37 From the Property Editor window, go to Input Data tab.
08:41 Under Compound Amounts tab, we can see that the benzene composition is 0.99.
08:49 Let us now check what reflux ratio is required for this.

To do this, click on the Distillation column.

08:58 Under Column Specs, click on Condenser tab.
09:02 Under Compound, we see a value of 2.382
09:07 It is the same as what we obtained in the Sensitivity Analysis.
09:13 Let me save this simulation as adjust.
09:20 Let's summarize.
09:22 In this tutorial, we have learnt to:

Determine the exact Reflux Ratio for a separation

09:29 Performed Sensitivity Analysis and Adjust operation
09:33 I have some assignments for you.
09:36 Simulate this problem statement using a Distillation column.
09:40 Here we give different Compounds, feed conditions and Thermodynamics.
09:46 Different Column Configuration
09:49 Let us go to the next assignment.
09:52 Perform sensitivity analysis on the simulated distillation column.
09:57 To find the reflux ratio such that mole fraction of water in bottoms is 0.99
10:05 Using Adjust/Controller Block, verify the results obtained using the analysis.
10:12 Watch the video available at the following link.

It summarizes the Spoken Tutorial project.

10:19 The Spoken Tutorial Project Team conducts workshops and gives certificates.

For more details, please write to us.

10:29 Please post your timed queries in this forum.
10:33 The FOSSEE team coordinates conversion of existing flowsheets into DWSIM.
10:39 We give honorarium and certificates for those who do this.

For more details, please visit this site.

10:48 The FOSSEE team helps migrate commercial simulator labs to DWSIM.
10:55 We give honorarium and certificates for those who do this.

For more details, please visit this site

11:04 Spoken Tutorial and FOSSEE projects are funded by NMEICT, MHRD, Government of India.
11:13 We thank the DWSIM team for making it as an open source software.
11:20 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

PoojaMoolya