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Levenspiel Plot

  1. Sep 21, 2014 #1

    Maylis

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    Hello,

    I am having some difficulty with levenspiel plots, in particular when dealing with a CSTR and when the reaction rate is increasing with conversion. I will give an example plot to demonstrate my point.

    Assume we are trying to find the volume of a CSTR necessary to reach a conversion of X = 0.5, with the levenspiel plot given below

    What I wonder, is how do I figure out what area should be taken, and why? I initially thought it would be the one in green, but I am missing something important here as far as how to use the levenspiel plot. When it is the other way around (reaction rate is decreasing with temperature), I can figure it out usually, but I seem to be missing something subtle.
     

    Attached Files:

  2. jcsd
  3. Sep 21, 2014 #2

    Maylis

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    This problem raises more questions yet still, what if X = 0.15? That is 0.15*400,000 = 60,000 m^3. Does that mean this reactor needs to be larger to have less conversion?
     

    Attached Files:

  4. Sep 22, 2014 #3
  5. Sep 22, 2014 #4

    Maylis

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    From that page, when it is normal plots (i.e. slope is up with X increases) I am good. It's only for the very specific case I gave that I am having some trouble. Why is it that it is the orange box, and not the green box for the area?
     
  6. Sep 23, 2014 #5
    You need to find [itex]\frac{F}{-r}\times X[/itex]. Geometrically (on the graph), that's the area of the orange box.

    Chet
     
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