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Specialty Chemistry Forums => Chemical Engineering Forum => Topic started by: cogujada on December 17, 2021, 08:09:08 AM

Title: Distillation McCabe - Thiele
Post by: cogujada on December 17, 2021, 08:09:08 AM

Hello!
I have a question about distillation using McCabbe-Thiele method... The distillation column is like this:

(https://www.chemicalforums.com/proxy.php?request=http%3A%2F%2Fimgfz.com%2Fi%2FQmljrDT.png&hash=44e51fd547c3397938f228d1cc236826efe2df6e)

As we can see in the image, we have a normal column, except that there is a feed (B ) on to the partial condenser. That makes things a bit difficult...
The question is about the net flows:

• Undoubtedly, there is a net flow in the Stripping section (where the boiler is, the lower part of the column). The net flow in that section would be:

(https://www.chemicalforums.com/proxy.php?request=http%3A%2F%2Fimgfz.com%2Fi%2FeaodbD4.png&hash=55967fe3370f9b11f5d1c74ef0c24ded248c1543)

So the net flow in the Stripping section is:
Δ_R=L_m-V_m=R
z_ΔR·Δ_R= L_m·x_m- V_m·y_m
This is correct 100% sure, but the problem is with other net flows. I do not know if there are more net flows. In a normal, usual column, we have the net flow in the stripping section (the one we have in the upper image), and the net flow in the rectifying section. However, as we have a feed (B ) in the partial condenser, I do not know if we have a net flow in the rectifying section. Does anyone know if we have a net flow in the rectyfying section? (as we have feed in the partial condenser).



Some people say there is only the net flow in the stripping section, and no net flow in other sections of the column. Other people think that we have the net flow in both the stripping section and the rectifying section, and finally, other people think we have the net flow in the stripping section and between the feed to the column (A) and the feed to the partial condenser (B ).



As for now, I only need to know the question to the following answer:

Do we have more net flows in the distillation column of the above image? (100% sure there is a net flow in the stripping section)



Thanks, please sorry for my low english-level, and again, thankyou very much!

Have a nice day.