Benzene from a stream of $N_2$ is to be separated in an absorption column followed by steam

stripping to recover benzene. The feed $(100$kmo$\frac{l}{h})$ enters the absorption column at $25C$ and is $90\%$

saturated with benzene. Not more than $2\mathrm{.}5\%$ of the feed benzene should leave the column. The feed

solvent has $0\mathrm{.}007$ mole benzene per mole of pure solvent $(mol.wt.=240).$ The loaded solvent leaving

the absorber has $0\mathrm{.}3$ mole benzene per mole of pure solvent. The solution is heated and fed to the

stripping tower to reduce the benzene content to $0\mathrm{.}007$ mole ratio so that the lean liquid can be cooled

and recycled to the absorption$.$ The steam rate used is $1\mathrm{.}5$ times the minimum. Both towers operate at

atmospheric pressure. The absorption tower operates at $25C$ and the stripping tower at $110C.$ The

equilibrium data at $25C$ are given below:

The Raoult's law may be used to determine the equilibrium relationship at the stripping temperature

of $110C.$ Vapor pressure of benzene can be calculated from the Antoine equation: $ln{P}^s=17\mathrm{.}5818-$

$(3867/$T$)$ where $P^s=$ vapor pressure in $mmHg$ and $T$ is temperature in $K.$

$($a$)$ Calculate the liquid rate to the absorber $($b$)$ Determine the number of ideal trays required for

absorption $($c$)$ What is the minimum possible steam rate? $($d$)$ How many real trays are required for

absorption if the Murphy Efficiency is $50\%?$