You must change the design for an old sieve tray column with $12-$inch tray spacing to operate at a

new reflux ratio which is $\frac{5}{3}$ of the reflux ratio in old design $(R^{\text{n}\text{e}\text{w}}=\frac{5}{3}{R}^{\text{o}\text{l}\text{d}})$ to keep the distillate

flow rate and concentration same as before. The new tray spacing needs to be increased to $24$

inches. Internal reflux ratio in old column was $(\frac{L}{V}{)}^{\text{o}\text{l}\text{d}}=0\mathrm{.}75.$ The value of the flow parameter in

old design was $F_{lv}^{\text{o}\text{l}\text{d}}=0\mathrm{.}09$ and the flooding velocity was calculated as $2\frac{m}{s}.$

Assume that: all the physical properties of the liquid and vapor phases are same as before, you

can treat the vapor phase as an ideal gas, pressure inside the column does not change, you do not

change the layout of the trays and downcomers, and the operating velocity in both old and new

designs are at $70\%$ of the corresponding flooding velocities.

what is the new flood velocity?