McCabe-Thiele Graphical Method Example Part 1
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- เผยแพร่เมื่อ 16 ก.ย. 2024
- Organized by textbook: learncheme.com/
Uses the McCabe-Thiele graphical method to determine the number of equilibrium stages in a distillation column. Part 1 of 2. Made by faculty at the University of Colorado Boulder, Department of Chemical & Biological Engineering. Check out our separations/mass transfer playlist: • Separations/Mass Transfer
Why cant you teach my separations class
em little confuse how to use q line and material balance for partially vaporized feed .....thanx for ur outstanding work..
at 3:44 what did value you take for x as for the feed operating line equation?
I'm confused why you added 1/6F in mass balance to find L(bar)?
Thank you for your question. The 1/6*F is from the problem statement where we know that for every 6 moles of feed, 1 mole of vapor is condensed. Does that answer your question?
LearnChemE
Is the value of V going to the condenser equal zero cuz it’s saturated liquid?
Beautiful work Sir, thank you for it.
I just wish you drew the minimum L/V line. Based on the shape of this equilibrium line, this might be a case where the minimum, if calculated between XD and the intersection of the q line with the equilibrium line is invalid due to an intersection of this line with the equilibrium curve at an X point between XD and the q-line intersection with the equilibrium line
This was a fantastic review, I am currently studying to take the P.E. exam and I needed a quick McCabe Thiele review. What program did you use to create the diagram in?
How did your exam go? :)
Is the feed line the same thing as the q line? Great video!
yes
I love your teaching 😍
For a partial condenser, should the mole fraction of the distillate be yd instead of xd?
You are absolutely right that with a partial condenser, we are treating the condenser as an equilibrium stage, and we have both vapor and liquid leaving the condenser with the vapor being the product and the liquid returned to the column. The vapor was specified as 95 mol% acetone, which is labeled on the plot as xD. It should have been labeled as yD. It does not change the solution though.
If all the vapor was condensed that left the partial condenser, it would be the same composition in the liquid state, so we could say xD in that case.
Very true. I didn't mean to be nit-picky. Your videos are absolutely amazing and very well explained. I'm lucky to have found a resource like this to help supplement my studying.
Consistently No its important to be "nit-picky". We want to make sure we dont have mistakes in the videos so we appreciate the feedback. Glad you are liking these.
Hello! I don't get why did you drew the feed line actually this way 3:49 and you haven't explained where are you getting those values from to determine slope line 5:48 . Not really clear...
Bart Tricas Thank you for asking and for putting the times into your question. Please clarify the first part of your question. I don't know what you are asking about the feed line. For the slope of the rectifying operating line, you use the distillate vapor mole fraction xD = 0.95. That point is on the x=y line, so y also equals 0.95 at that point. The other point is drawn at the pinch point where an infinite amount of stages would be needed. This is where the feed line intersects with the vapor-liquid equilibrium line (0.53, 0.69).
LearnChemE Same problem here. From the video, the feed operating line is y=7x-3. But I still don't get it how you drew that line.
FabIrsy If you are asking about what software is used, I can find that out. But basically, it is a line with a slope of 7 and a y-intercept of -3. With the y-intercept being so far off the plot, it may be easier to draw the line by solving for x when y = 0 (x = 3/7 or 0.43). Another point on the feed line is (0.5, 0.5).
Bart Tricas
y=7x-3
The x intercept (x value when y=0) is (3/7) or abt 0.4286, and the y intercept (y when x=0) is -3, off the bottom of screen.
Draw a line thru the points (0.4286, 0) and (0, -3) to get the feed line.
Only the part between the 45 degree line and the LVE is of interest.
LearnChemE Thank you for the explanation, it's clear now. So, what software did you use? Because at my university we learn McCabe-Thiele graphical method by doing it manually without software.
Very good class, congratulations
How can I get the equilibrium curve? .(the blue curve)
You can obtain the equilibrium curve through collecting experimental or published data, or using a thermodynamic equilibrium model (like Raoults, or Peng-Robinson, etc.)
LearnChemE I think the person meant for this exact problem, it doesn't give us any basis to make the equilibrium curve.
Christopher Luu Thanks for clarifying. you are right that the problem is not specific in operating conditions. You would need to look up equilibrium data or use an appropriate model. I used atmospheric pressure to plot the data.
If Raoults law is used we would assume that the solution is ideal. yP=xPsat. Pressure is constant but temperature would vary. Therefore, the temperature along the distillation column is varying but not the pressure... Is this correct?
any on Ponchon Savarit method ?
We don't currently have any screencasts on the Ponchon-Savarit method, but I will add that to our list of future separations screencast topics. Thanks for the suggestion!
Great work guys
Sir if its mention in question that feed is saturated liquid then in that case q=1, when i put q=1 in the q line equation answer in infinity? what should i do now?
Thank you for your question. The q referred to here is not the same as steam quality. Here it refers to the feed state and how many moles of liquid are in the feed stage per mole of feed. See 1:45 in the video. I hope that helps.
Where do you get the x and y values of Acetone?
Are you asking about the data to create the plot? That is vapor-liquid equilibrium data that you can find in tables online or in textbooks. I hope that helps.
U can get the values for acetone standard no matter which ever state it is entering as feed
In Perry's handbook
It is the standard get its latest edition u will come to know
Ok it's available online in PDF format also just search and get it so simple
Fine
thanks a lot guys, you were such a help!
how do i plot the q-line/feed line ? tq
+ameerahaina Thanks for your question. Please see the responses below and let me know if it's still not clear.
why Zf=0.5?
That is given in the problem statement. The feed is equimolar, so it is 50% acetone and 50% ethanol.
Can you please tell me how did you plot (y=7x-3) on the diagram ?!
5:35