Question $3[20]$

A tray absorption tower is used to absorb CO gas from an air gas stream using water at $303K$ and $1$atm. The flow rate of the gas steam is $70\mathrm{.}0$kgmo$\frac{l}{h}$ and it contains $2\mathrm{.}5$mol$\%CO.$ the absorbed gas $CO$ is optimally recovered up to $85\%.$ The equilibrium relationship is $y=0\mathrm{.}68x$ for this dilute stream. Using $1\mathrm{.}5$ times the minimum liquid flow rate, determine the number of trays needed using both the graphical and the analytical Kremer equation.