Stripping section operating line

Stripping section oper. line stepping off stages... 

It is also known that D=V, and when this expression for D is substituted in the above equation, the result is Y=X= Kj. That is, the rectifying section operating line intersects the diagonal at the distillate composition. Similarly, it may be shown that the stripping section operating line intersects the diagonal at Y = X = Xf the bottoms composition. 

Tj and Vj. The above equation, rearranged, is the stripping section operating line ... 

The intersection of the stripping section operating line (8-21) with the (x = y) line is given by... 

Intersection of the q-line, Xp = 0.3 (saturated liquid) with the enriching section operating line is located at point P. The stripping section operating line must also go through this point. 

The slope of the stripping section operating line is found by trial and error, since there are three equilibrium contacts in the column with the middle stage involved in the switch from one operating line to the other. The result is Xb = 0.07, and the amount of distillate is obtained from the combined total and hexane overall material balances (as in Example 8.5a). 

A superheated direct steam input or a superheated boilup from a total reboiler will cause vaporization of liquid inside the column. This is equivalent to a net increase in the boilup ratio, E/B, and makes the slope of the stripping section operating line approach 1.0. Since superheated vapor inputs can be analyzed in the same fashion as the subcooled liquid reflux, it will be left as homework assignments 4.C14 and 4.C15. 

In a composite column, the point of intersection of the extraction and stripping section operating lines is always at the feed concentration, i.e. 

We use the stripping-section operating line to step off the stages as shown in Figure 4.74. The stages are numbered on the equilibrium line. Where do we stop stepping The answer comes from the analysis of the rectifying section. 

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