A saturated vapour feed of 2250 kmol/h consists of 50 mol% methane, 30 mol%propane and 20 mol% n-butane. A distillate recovery of 99 mol% propane and bottoms recovery of 97.5

mol% n-butane is desired. \text { The average relative volatility is } \alpha_{\text {methane-propane }}=9.92 x_{\text {propane-propane }}=\text { and } \alpha_{\text {butane-propane }}=0.49 Constant molar overflow (CMO) is valid. Reflux is returned as a saturated liquid. Thecolumn has a partial reboiler and a total condenser. \text { Calculate the value of } \phi You must state the answer in 4 decimal places.