DWSIM-3.4/C2/Rigorous-Distillation/English-timed

Time	Narration
00:00	Welcome to the spoken tutorial on Simulating a Rigorous distillation column in DWSIM.
00:07	My name is Kannan Moudgalya.
00:10	In this tutorial, we will carry out a rigorous simulation of a Distillation column.
00:15	We will learn to specify column pressure profile.
00:20	We will see where to specify tray efficiencies.
00:23	We will check whether the product compositions are as desired.
00:29	We will also learn how to view the column profiles.
00:34	To record this tutorial, I am using DWSIM 3.4.
00:39	To practice this tutorial, you should know:
00:41	* How to open a simulation file in DWSIM
00:45	* How to add components to a flowsheet
00:47	* How to select thermodynamic packages
00:51	* How to add material and energy streams and specify their properties.
00:57	Our website spoken tutorial dot org gives details of the prerequisite tutorials.
01:05	You can access these tutorials and also all the associated files from this site.
01:12	This slide shows the problem solved in one of the prerequisite tutorials.
01:17	This was solved using shortcut distillation.
01:23	Let us open the corresponding file in DWSIM.
01:28	I have already opened DWSIM.
01:31	I have already loaded the file shortcut dash end dot dwxml.
01:38	This file is available to you for download from our website spoken tutorial dot org.
01:45	Let me save this as "rigorous".
01:58	You can see that the file name has changed now to "rigorous".
02:03	Click on the Configure Simulation button.
02:06	Below the Thermodynamics tab, locate the Options menu.
02:13	Let me click it.
02:15	In the white space above it, you get an option called Units System. Let me click it.
02:22	Locate Pressure on the right hand column.
02:26	To see that, let me bring this here.
02:30	Change its units to atmosphere.
02:35	Similarly, change the units of Delta_P also to atmosphere.
02:42	Change also the units of Molar flow rate to kilo moles per hour.
02:50	Click on Back to simulation.
02:53	Let us switch to the slides.
02:56	The file we opened just now in DWSIM, solves the problem in this slide.
03:02	The solution is given in the next slide.
03:05	This problem was solved in the spoken tutorial on shortcut distillation.
03:11	These values form the basis for the rigorous distillation column problem.
03:17	You may want to write down these values in a piece of paper.
03:20	We will be using these values shortly.
03:24	Let us begin by replacing the Shortcut column with a rigorous distillation column.
03:31	Let me go back to the simulation.
03:33	Press right-click on the Shortcut column and delete it.
03:40	Answer yes to the prompt.
03:43	Locate the Distillation column in the Object Palette.
03:46	Click on it and drop it in the place of shortcut distillation column.
03:52	You may have to adjust its position.
03:55	Click the column and select it.
03:59	Go to the Selected Object window.
04:02	Under the Properties tab, locate the Connections menu.
04:05	It is the third item.
04:08	In this, we can see Edit Connections. Click on it.
04:13	Immediately after clicking it, a button appears at the right extreme;
04:16	a button with three dots, click on it.
04:21	Now, there is a pop-up window.
04:23	Under the Feeds menu, click on the + (plus) button which is the Add button.
04:29	Under To Stage column, the option is Condenser by default.
04:36	Here, we have to specify the stage at which the feed enters.
04:41	Click on the arrow next to the Condenser.
04:44	In my version of DWSIM, I had to click a second time.
04:49	We can see the list of stages.
04:51	Select the stage where we want the feed to enter the Distillation column.
04:57	Here we select Stage_6.
05:00	Now, we will select the material stream.
05:03	Click on the down-arrow below the Stream menu.
05:08	You may have to click this also twice.
05:10	Click on Feed.
05:12	We have done the pairing that the Feed should go to Stage_6.
05:17	The actual connection will be done later in the flowsheet.
05:22	This is as per the solution we got in the shortcut distillation column.
05:27	Let us see it in the slide, we see the optimal feed location to be six.
05:31	Let us go back to DWSIM.
05:35	In a similar way, we have to pair the product streams.
05:39	Pair the Condenser to Distillate,
05:42	pair the Reboiler to Bottoms.
05:46	Now, we will connect heat duties to reboiler and condenser.
05:50	Pair C-Duty with Condenser and R-Duty with Reboiler.
05:58	We will now convert all the pairing into connections.
06:02	Click on any one of Feed or Condenser or Reboiler.
06:09	This completes the connections indicated by pairing.
06:14	We can move this and check.
06:17	You can see the connections have been made.
06:21	Let me close this.
06:24	Let me shift some streams to make it look more beautiful.
06:35	Click the Column and select it.
06:37	Under Properties tab, locate the Column Properties section.
06:43	It is the first option.
06:44	This section is used to specify the various attributes of a Distillation Column.
06:51	In this section, the first option is Condenser Pressure.
06:55	By default, it is 1 atmosphere.
06:59	We will leave it as it is.
07:00	Next is the Reboiler Pressure.
07:04	I will change its value to 1.1 atmosphere.
07:09	Using this, I will show how to establish a linear profile in the column.
07:16	Locate the Number of Stages option next.
07:20	You have to enter the total number of trays here.
07:24	Enter 15 here.
07:27	Because, this number includes the condenser also in DWSIM.
07:32	We plan to use a total condenser.
07:33	So, this number should be one more than the equilibrium stages given by shortcut method.
07:41	We got the equilibrium stages to be 14 from the shortcut method.
07:47	We can see it in the slide.
07:50	Let us go back.
07:51	The next option is Edit Stages. Click it.
07:57	Press the button at the right extreme.
08:01	It shows the condenser and reboiler pressures at 1 and 1.1 atmosphere.
08:08	These are the values that we entered just now.
08:12	The new stages that have been added have been assigned zero pressures which is incorrect.
08:20	We would like, infact, all the intermediates stage pressures to take interpolated values.
08:28	Go to the left column and click the interpolation symbol at the bottom.
08:35	Immediately, linearly interpolated values are assigned to every stage.
08:41	One may also change the pressure in any of the stages one through thirteen.
08:47	For example, I will click this pressure and change it to one (1) atmosphere.
08:56	Let me undo this by pressing the interpolated values again.
09:02	This is a very useful and important method.
09:05	Whenever the number of trays changes, you will have to press the interpolate button.
09:10	If you forget this, there could be a lot of problems.
09:14	For example, there could be negative flow rates.
09:18	Remember to do this in Assignment 3, at the end of this tutorial.
09:22	One may also change the efficiency in one or more stages, as given here.
09:30	Close this popup.
09:32	Next we have the Condenser type.
09:35	For that, we have to go up.
09:38	By default, it is Total condenser.
09:41	We will leave it as it is.
09:44	Next we have Condenser Pressure drop in atmosphere. By default, it is 0.
09:49	We will leave it as it is.
09:53	Next we have Condenser Specifications.
09:56	Under this menu, we have the type as Stream_Ratio by default.
10:03	Below this, we can see the Value menu.
10:07	Click on the field besides it.
10:10	Enter the required Reflux ratio.
10:13	Here we enter it as 2.
10:16	Recall that the minimum reflux ratio from the shortcut distillation was 1.47.
10:26	By multiplying 1.47 by 1.3 and rounding it off, we get 2.
10:33	Next we have Reboiler Specifications.
10:38	Under this menu, we have the type as Product Molar Flow Rate by default.
10:47	Change the units to kmol/per hour, if necessary.
10:55	We see the Value menu.
10:58	Enter the required Molar flow rate. Here we enter it as 61.1.
11:05	This is suggested by the shortcut solution.
11:09	We can see it in the slide.
11:13	Now we will select the solution method.
11:17	Locate the Solving Method option from the Properties tab; it is item 7.
11:26	Click on the field besides it.
11:30	Click on the arrow on the right extreme.
11:33	We can see a list of solving methods.
11:36	Select WangHenke_BubblePoint.
11:41	Now we will run the simulation.
11:43	To do this, go to the calculator options.
11:47	Click on the Play button.
11:50	Now click on the Recalculate All button.
11:55	When the calculations are completed, click the product compositions.
12:01	Choose a stream, for example, distillate.
12:05	You know how to check the product compositions from the molar compositions option.
12:15	Now, click on the Distillation column.
12:19	Under Properties tab, locate the Results menu. It is item 8.
12:27	This shows all the required results like Condenser Duty, Reboiler Duty and Column Profiles.
12:34	To see the Column profiles, click on it.
12:39	We can see the button appearing on the right extreme; click on it.
12:44	Now we can see the pop-up window.
12:46	We can see the temperature and pressure profiles,
12:51	Flows profiles,
12:53	Component flows and Component fractions.
12:58	If you want to know the exact numbers, use the Table tab to the right of the Graph tab.
13:07	Let me close this.
13:10	Let us save this file.
13:15	Let me summarize.
13:17	We learnt how to simulate a rigorous Distillation column,
13:21	Specified pressure profile,
13:23	Found out where to give tray efficiencies,
13:26	Verify column profiles.
13:30	Let me give some assignments.
13:33	Repeat the calculations for a constant column pressure of 1 atmosphere. That is, with reboiler pressure = 1 atmosphere.
13:42	Do you see major changes in the results?
13:46	Next, simulate the distillation column at a constant pressure of 1 atmosphere. That is, the reboiler pressure also is at 1 atmosphere.
13:55	If the reflux ratio is increased beyond 2, does the purity improve?
14:01	What reflux ratio should you use, if the actual purity is as desired.
14:07	In a future tutorial, we will show how sensitivity analysis can help do this easily.
14:16	In the next assignment, we simulate the column at a reflux ratio of 2.
14:22	Keep the column pressure constant at 1 atmosphere.
14:24	Increase the total number of trays by 1, that is, from 15 to 16.
14:31	As the number of trays has changed, you have to use the interpolate option.
14:36	This was mentioned earlier also.
14:38	With a larger number of trays, has the purity increased?
14:44	In the next assignment, verify the following relationship:
14:48	Composition of vapour flow to the condenser = distillate product composition.
14:54	Explain why this equation has to be satisfied.
14:58	In the next assignment, check the consistency of the variables of the reboiler.
15:03	Use compositions, temperature and pressure at the reboiler for this purpose.
15:10	Do this through an equivalent flash calculation.
15:15	In the last assignment, solve the problem by different Solving Methods.
15:20	Compare the results.
15:21	Compare the computation times.
15:25	We have come to the end of this tutorial.
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Contributors and Content Editors

Nancyvarkey, PoojaMoolya, Pratik kamble, Sandhya.np14