DWSIM-3.4/C2/Sensitivity-Analysis-and-Adjust/English-timed
From Script | Spoken-Tutorial
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| 00:00 | Welcome to this spoken tutorial on DWSIM. |
| 00:04 | In this tutorial, we will learn how to do sensitivity analysis and adjust. |
| 00:10 | My name is Kannan Moudgalya. |
| 00:12 | In this tutorial, We will determine the exact Reflux Ratio for a separation. |
| 00:19 | We will first do this through Sensitivity Analysis. |
| 00:24 | We will repeat this through the Adjust operation. |
| 00:28 | To record this tutorial, I am using DWSIM 3.4. |
| 00:34 | To practice this tutorial, you should know:
How to open a simulation file in DWSIM How to carry out rigorous distillation simulation. How to add components to a flowsheet. |
| 00:48 | Our website- spoken tutorial dot org gives details of the prerequisite tutorials. |
| 00:55 | You can access these tutorials and also all the associated files from this site. |
| 01:02 | This slide shows the problem solved in one of the prerequisite tutorials. |
| 01:08 | This was solved using Rigorous distillation. |
| 01:12 | The purity achieved was less than what was desired. |
| 01:17 | How do we improve the purity? |
| 01:19 | We need to increase the reflux ratio. |
| 01:23 | Let us open the corresponding file in DWSIM. |
| 01:28 | The file name is in the heading. |
| 01:30 | I have already opened DWSIM. |
| 01:34 | I have already opened the file rigorous dot dwxml. |
| 01:40 | This file is available to you for download from our website spoken-tutorial.org. |
| 01:48 | Let us click Distillate. |
| 01:50 | In the Properties section, let us locate Molar Composition, item 2. |
| 02:00 | Let us click the arrow next to Mixture. |
| 02:04 | The Benzene mole fraction is 0.945. |
| 02:09 | We would like to increase this to 0.95. |
| 02:13 | Let us attempt this by increasing the reflux ratio. |
| 02:18 | This is what we saw in the slide, a little while ago. |
| 02:22 | Locate the Optimization option from the Menu bar, to the right of the File button. |
| 02:28 | Let me click it.Let me click the option Sensitivity Analysis. A window appears. |
| 02:37 | We can see five menus in the menu bar of sensitivity analysis. |
| 02:43 | Locate Sensitivity Studies. |
| 02:47 | If it is not already selected, click it. |
| 02:51 | Now we can see a box with four options under the title Case Manager. |
| 02:58 | Click on New option. |
| 03:01 | This will help in creating a new Sensitivity Analysis case. |
| 03:07 | We see the name SACase0. |
| 03:12 | Recall the problem that we want to solve: |
| 03:14 | We want to increase the reflux ratio so as to get better purity. |
| 03:19 | Thus, reflux ratio is the independent variable. |
| 03:24 | Let us enforce this through the Independent Variables button. |
| 03:29 | Let me click on empty space besides the Object button. |
| 03:34 | Click on DC-000, the name of our distillation column. |
| 03:40 | On the right hand side, there is an option called Property. |
| 03:45 | Let me bring this inside. |
| 03:47 | Let me click the down-arrow. |
| 03:50 | Let me scroll down and identify Condenser_Specification_Value. |
| 03:55 | It comes at the bottom of this menu. |
| 03:57 | It plays the role of reflux ratio. |
| 03:59 | Click and select it. |
| 04:03 | You can see it here, selected. |
| 04:07 | Recall that we want our reflux ratio to be greater than 2. |
| 04:12 | So, we will enter the Lower limit as 2. |
| 04:16 | Change the Upper limit to 2.5. |
| 04:20 | Change the Number of Points to 6. |
| 04:24 | Let us next click on Dependent Variable. |
| 04:27 | On the left hand side, see a column called Variables. |
| 04:33 | Below that, see a plus button in green to Add variables. Click it. |
| 04:41 | A new row appears. Click the down-arrow below the Object. |
| 04:46 | You may have to click it twice. |
| 04:48 | Click on the option named Distillate. |
| 04:52 | Let me click the down-arrow below Property. |
| 04:56 | You may have to click this also twice, to open a drop-down menu. |
| 05:01 | Locate Molar Fraction (Mixture) – Benzene. |
| 05:05 | You will have to scroll down to reach it. |
| 05:08 | There are also other options that sound very similar to it. |
| 05:12 | Make sure that you choose this. Click it. |
| 05:17 | It gets selected and appears on the tab. Then click on Results. |
| 05:24 | We can see the option called Start Sensitivity Analysis.. Let me click it. |
| 05:31 | We see the column getting simulated for reflux ratios, one by one. |
| 05:36 | At the end of the simulation, we get the message Done. |
| 05:40 | You see results for six reflux ratios, from 2 to 2.5. |
| 05:49 | We also see the corresponding benzene compositions. |
| 05:54 | We can go back to Independent Variables. |
| 05:58 | Change the number of points to 11. Return to Results. |
| 06:05 | Click Start Sensitivity Analysis once again. |
| 06:10 | You can see that eleven runs get completed. |
| 06:14 | Let us scroll up. |
| 06:17 | See that the desired purity of 0.95 will be achieved between 2.05 and 2.1. |
| 06:26 | You may choose these as the lower and upper limits in Independent Variables and repeat. |
| 06:34 | But, I will not do that now. |
| 06:36 | Continuing in this manner, we can determine the exact reflux ratio required for 0.95 purity. |
| 06:45 | I have an assignment for you.Can you find out the reflux ratio required for 0.95 purity? |
| 06:52 | Follow the procedure I explained just now. |
| 06:56 | I will give you the answer: It is approximately 2.067. |
| 07:01 | We can also see these results in a graphical form. |
| 07:07 | Click on Chart option. |
| 07:10 | Click on Draw option. You can see the chart here. |
| 07:15 | Distillate composition versus condenser specification value, that is, the reflux ratio. |
| 07:24 | Let me close this pop-up. |
| 07:26 | Let me save this simulation as "sensitivity". |
| 07:36 | Let us go to the next assignment. |
| 07:39 | In the previous assignment, include a second dependent variable: Benzene mole fraction in the bottoms. |
| 07:46 | Observe both distillate and bottoms compositions. |
| 07:51 | Find out how to plot two profiles using Chart. |
| 07:55 | Let us do another assignment. |
| 07:59 | Verify whether the reflux ratio of 2.067 that we saw in assignment 1 will work. |
| 08:06 | For this, start with rigorous.dwxml once again. |
| 08:11 | Change the reflux ratio to 2.067. |
| 08:15 | Simulate. |
| 08:17 | What distillate composition do you get? |
| 08:20 | We calculated the desired reflux ratio by trial and error. |
| 08:27 | DWSIM has a powerful method to directly calculate this. |
| 08:32 | It is called Adjust. |
| 08:35 | Let us locate Adjust from the object palette on the right hand side. |
| 08:42 | Drag it to flowsheet and drop it outside the column, below the distillate. |
| 08:49 | Let me click and choose it. |
| 08:52 | In the Properties tab, we see an option called Controlled variable. |
| 08:58 | This corresponds to the dependent variable, namely, distillate composition. |
| 09:05 | If it is not already opened, click the arrow to the left of the Controlled Variable and, this will open up. |
| 09:13 | Click where it says Click to Select. |
| 09:17 | Click the button that comes at the right end. |
| 09:19 | A pop-up appears.It has three columns. |
| 09:23 | Below Type, click on Material Stream, if it is not already selected. |
| 09:29 | In the Object column, that is, in the middle column, choose Distillate. |
| 09:35 | This produces a lot of variables on the right most column. |
| 09:39 | Locate Molar Fraction (Mixture) – Benzene . |
| 09:44 | It comes after Solid Phase entries are over. Click it. |
| 09:51 | Once again, be careful, as there are many similar sounding options. |
| 09:55 | Click OK. |
| 09:58 | Verify that this gets reflected in the Properties menu. |
| 10:04 | Repeat the above process; but now, with Manipulated Variable. |
| 10:09 | Click the button on the right. |
| 10:12 | In the pop up, scroll down and locate Distillation column. Click on it. |
| 10:18 | Then click DC-000. Then locate Condenser_Specification_Value. |
| 10:26 | Click it and then OK. |
| 10:31 | Follow the usual procedure, now for Parameters property. |
| 10:36 | Scroll down to see this. |
| 10:40 | We can see an option called Adjust Property Value. |
| 10:43 | This value is generally 1. |
| 10:48 | Delete 1 and enter 0.95. |
| 10:52 | I shall enter a slightly larger number 0.95001. |
| 11:00 | I want you to think about why I have entered a slightly larger number. |
| 11:06 | A few lines below this, see an option called Simultaneous Adjust. |
| 11:11 | Following the usual way, change its value to True. |
| 11:18 | If it does not automatically calculate, press Play and then Recalculate All. |
| 11:26 | In my case, it calculated automatically. So, I shall not click those. |
| 11:32 | In a short time, calculations get completed. |
| 11:35 | Let us check whether our objective of 0.95 for distillate purity is achieved. |
| 11:42 | Choose Distillate. |
| 11:44 | Check Mixture under Molar Composition. |
| 11:49 | We can see that benzene composition is 0.95. |
| 11:53 | Let us now check what reflux ratio is required for this. |
| 11:59 | For this, click on the Distillation column. |
| 12:02 | Check the value under Condenser Specification. |
| 12:08 | We see a value of 2.067. |
| 12:13 | It is the same as what we obtained in the Sensitivity Analysis. |
| 12:18 | Let me save this simulation as "adjust". |
| 12:27 | I have the next assignment for you. |
| 12:29 | Supposing that I want 0.96 benzene mole fraction in the distillate. |
| 12:36 | What reflux ratio is required? |
| 12:39 | As in the problems we solved, you may change only the reflux ratio. |
| 12:44 | Solve this first by Sensitivity Analysis. |
| 12:47 | Check your calculations with Adjust. |
| 12:51 | Let us do one more assignment.Find the highest distillate purity you can get in this column. |
| 12:58 | You may vary the reflux ratio only, as in the earlier assignments. |
| 13:03 | I could go up to a mole fraction of 0.99, by proceeding gradually. |
| 13:10 | Let me summarize. |
| 13:12 | We learnt the following in this tutorial: |
| 13:14 | how to do Sensitivity Analysis |
| 13:16 | how to narrow the solution range |
| 13:18 | how to directly achieve the same results using Adjust |
| 13:22 | how to use Adjust to push a plant to deliver more. |
| 13:27 | We have come to the end of this tutorial. |
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