Determine the operating equations for CMO systems

Operating equations for CMO distillation

Much like in flash distillation, it is useful to recast our material balance expressions in the form y = F(x) (to facilitate future graphical solutions).


Assuming CMO in order to perform distillation calculations is often called the Lewis Method.

In order to obtain these operating lines, we recall the generic balance equations for each section of the column. For the rectifying section, we have:

Vj+1 = Lj + D

yj+1Vj+1 = xjLj + xDD

Applying the assumption of CMO, these become:

V = L + D

yj+1V = xjL + xDD

Combining them, we get the rectifying section operating equation:

yj+1 = xj(L/V) + xD(1-L/V)

For the stripping section,

V' = L' - B

yf+1V' = xfL' - xBB

which gives us the stripping section operating equation as:

yf+1 = xf(L'/V') - xB(L'/V'-1)


L does not generally equal L'.


Determine the operating equations for CMO systems