Example

${?}^1$ A liquid mixture containing $10$mol$\%$ n$-$heptane and $90$mol$\%n-$octane is fed at its boiling point to the top of a stripping tower at $101\mathrm{.}32kP.$ Figure E$4\mathrm{.}4-5$ depicts a stripping tower where the feed stream is the saturated liquid and the distillate stream is the saturated vapor. There is no reboiler or condenser in a stripping tower. The bottoms are to contain $98$mol$\%$ n$-$octane. For every $3$mol of feed, $2$mol of vapor is withdrawn as product. Calculate the composition of the vapor and the number of theoretical plates required. The equilibrium data are given below