A mixture of xylenes plus other aromatics is separated in a large fractionating column operating at atmospheric pressure. Calculate the minimum number of plates and the minimum reflux ratio for the conditions in Table 22.4. Use the Gilliland correlation to estimate the reflux ratio that will permit the separation to occur in 100 ideal stages The relative volatilities are calculated for 18 lb_ƒ/in.² absolute and 150°C, the estimated conditions near the feed tray.

Table 22.4

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TABLE 22.4 LK HK Component Ethyl benzene p-Xylene m-Xylene o-Xylene n-Propyl benzene Boiling point, "C 136.2 138.5 139.1 144.4 159.3 0.054 0.221 0.488 0.212 0.025 a 1.23 1.15 1.13 1.0 0.70 % recovery in D 99.0 3.8