$(22$ marks $-22$min $)$ A process consisting of an absorption tower and a stripping tower is used to

separate the components of a gas containing $27\mathrm{.}0$ mole$\%$ component A and the balance component

B$.$ A stream of this gas is fed to the absorber$.$ A liquid containing $0\mathrm{.}480$ mole$\%$ dissolved A and the

balance $B$ is recycled from the stripper and fed to the absorber$.$ The product gas leaving the top of the

absorber contains $1\mathrm{.}00$ mole$\%$ A and essentially all of the B fed to the unit. The A$-$rich liquid solvent

leaving the bottom of the absorber is fed to the stripper and a stream of nitrogen gas is fed to the

stripper. Eighty$-$five percent of the $A$ in the liquid feed to the stripper comes out of solution, and the

nitrogen$/$A stream leaving the column passes out to the atmosphere through a stack. The liquid

stream leaving the stripping tower is the $0\mathrm{.}480\%$ component A solution recycled to the absorber$.$

a$.$ Taking a basis of $100mo\frac{l}{h}$ of gas fed to the absorber$,$ draw and label a flowchart of the process.

For the stripper outlet gas, label the component molar flow rates rather than the total flow rate

and mole fractions. $(/14$ marks$)$

b$.$ Calculate the molar flow rate $($in $mo\frac{l}{h})$ of A entering the stripping unit and the molar flow rate

$($in $mo\frac{l}{h})$ of the liquid stream exiting the stripping unit and entering the absorption unit. $(/$&