$(27$ pts$)$ Air stripping columns are commonly used to remove volatile organic compounds $($VOCs$)$ from water. You are tasked with designing a stripper to remove dichloromethane $($a common VOC$)$ from water. The column will operate isothermally at $20C$ and isobarically at $760mmHg.$ The entering liquid stream contains $1\mathrm{.}0$mol$\%$ dichloromethane $DCM$ in water $W$ at $20C$ at a flow rate of $50mo\frac{l}{h}.$ The entering vapor stream is pure air $A$ at $20C.$ The required outlet liquid must contain no more than $0\mathrm{.}15$mol$\%DCM$ to meet EPA regulatory requirements. $\frac{G^{\text{'}}}{G^{\text{'}}{?}^{\text{'}}}$min$=2.$ Assume solute free flow rates are constant, meaning water is nonvolatile and air does not dissolve in water. Graphs needed are provided at the end of this document.

a$)$ Draw a PFD and label using solute free flowrates and mole ratios $(4$ pts$)$

b$)$ Determine the minimum gas solvent flowrate required $(G_{\text{m}\text{i}\text{n}}^{\text{'}})(8pts)$

c$)$ Determine the equation of the operating line $(8pts$

d$)$ How many stages $(N)$ are required to get the desired separation? $(7$ pts$)$