Binary Flash Distillation Example

Organized by textbook: learncheme.com/
Example problem focused on determining the operating conditions for a binary flash distillation column. Made by faculty at the University of Colorado Boulder Department of Chemical and Biological Engineering.
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[@LearnChemE]

You can do that as well to solve for z, but if you want to draw the line it helps to determine the y-intercept.

[@LearnChemE]

Yes, its important for the phase equilibrium data to accurately use correct models or data extracted from studies. In this case we had a methanol/water system and were using Raoult's law to predict the equilibrium data. You mention Ethanol, which does exhibit an azeotrope, so it would be important to account for this.

[@wxuesiwei]

In (c), why not just put the point (0.23,0.6)into the operating function y=-x+2z?

[@jponce08]

Hi LearnChemE, thanks for the video! - just one little comment; I used the Empirical Model VLE for nonideal mixtures, with values from DECHEMA at 1 atm. Ethanol/Water are treated as a mixture with minimum boiling azeotropes and by this method Xetoh = 0.32 ..

[@nitroneonicman]

The way that we solve for the composition of the feed it seems like if our slope is any higher we can have a composition over 1 which doesn't make sense, and there are several other LearnChemE examples where this would be the case...

[@LearnChemE]

@jponce08 Please check out our site...learncheme . com for more examples as well. They should all be in our channel here too.

[@jponce08]

Dear LearnChemE; Where could I find more examples? I have an exam coming up and want to gain practice working out problems on as many exams as I can.. Thanks

[@KasunSamarasiri]

Thanks!

[@jassahib]

That was amazing ...

[@tareq155]

can you please explain to us why the feed methanol molar fraction in the liquid is equel to the molar fraction in the gas phase , why have you made that assumption ?

[@LearnChemE]

The feed composition is 0.4 Methanol based on the operating line material balance. Once it is fed to the flash tank, it separates into a vapor and liquid phase. The vapor phase is 0.6 mole fraction MeOH and the liquid fraction is 0.23 MeOH (the other parts being water).

[@tareq155]

when you the operating line crosses the y=x line , it represents the ( zfeed, zfeed) , can you please tell me what you mean by that , since the feed is liquid only , thanks.

[@LearnChemE]

tareq hassan the nomenclature of some textbooks call the feed composition zfeed, zfeed. Typically the feed enters as a liquid and passes through a throttle before entering a flash tank. The z is to differentiate it from x (liquid) or y (vapor) since it isnt being read in that sense. The operating line just indicates that at the intersection of the y=x line, we know the feed composition is 1 value.

[@tareq155]

LearnChemE thanks you sir, i tried to analyze it starting from y=zF/V-xL/V, so when F/V=0 , y=x , and i thought that made no sense.

[@mansaurussaad7019]

bro I was just surfing youtube and ended up here I dont understand

[@egetezer7790]

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[@nihadakhmadli7605]

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[@lucacirea5625]

At the beginning you wrote "kmol/hr" instead of "kmol/h"... HOW DARE YOU!