A dilute aqueous solution of methanol is to be stripped with steam in a sievetray tower. The conditions chosen for design are

The equilibrium data at this concentration indicate that $m=2.5$ (Perry and Chilton, 1973).

(a) Design a suitable cross-flow sieve tray for such a tower. Take $d_{o}=6.0 \mathrm{~mm}$ on an equilateral-triangular pitch $12 \mathrm{~mm}$ between hole centers, punched in stainless-steel sheet metal $2 \mathrm{~mm}$ thick. Use a weir height of $50 \mathrm{~mm}$. Design for an $80 \%$ approach to the flood velocity. Report details respecting tower diameter, tray spacing, weir length, gas-pressure drop, and entrainment in the gas. Check for excessive weeping.

(b) Estimate the tray efficiency corrected for entrainment for the design reported in part (a).

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Temperature = 368 K Liquid: Rate 0.25 kmol/s Density 961 kg/m Surface tension = 40 dyn/cm Pressure 101.3 kPa = Composition = 15.0 mass% methanol Diffusivity 5.70 10-5 cm/s (est.) Vapor: Rate 0.1 kmol/s x Viscosity = 125 P (est.) Viscosity 0.3 CP Foaming factor = 1.0 Composition 18 mol% methanol Diffusivity = 0.213 cm/s (est.)