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Unformatted text preview: antly more pressure drop than the column with Montz packing. The pressure drop is not critical. Because of the much higher cost for Montz packing and the much smaller diameter for the NOR PAC column, it is probable that economics would favor the NOR PAC column. Exercise 7.53
Distillation of a mixture of benzene and toluene in a packed column. Given: Conditions in Example 7.1, but using 50-mm Hiflow rings at 70% of flooding. Assumptions: Constant molar overflow. Partial reboiler is an equilibrium stage. Find: (a) Liquid holdup. (b) Column diameter. (c) HOG. (d) Packed height. (e) Pressure drop. Advantages of packed column over trayed column. Analysis: At the top of the column, L = RD =1.59(275) = 437 lbmol/h, and V = L + D = 437 + 275 = 712 lbmol/h. At the bottom of the column, for constant molar overflow and 61.1 mol% feed vapor, V = 712 - 0.611(450) = 437 lbmol / h, and L = V + B = 437 + 175 = 612 lbmol / h Before computing liquid holdup, we need to compute column diameter.
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