520 0362 weir length lw 425 in volumetric liquid

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Unformatted text preview: liquid density = 59.5 lb/ft3 or 954 kg/m3, and = 58 dyne/cm = 0.058 kg/s2, h = 6 / g L DBmax = 6(0.058) / (9.8)(954)(0.00476) = 0.0078 m = 0.31 in. liquid From Eq. (2), ht = hd + hl + h =2.28 + 1.08 + 0.31 = 3.67 inches liquid = 0.125 psi/tray. This pressure drop is a slightly on the high side. (c) From Fig. 6.28 for the top tray, with FLV = 0.0192 and % flood = 95%, fractional entrainment = = 0.50, which is fairly high. From Fig. 6.28 for the bottom tray, with FLV = 0.0473 and % flood = 51%, fractional entrainment = = 0.017, which is low. The fractional entrainment is defined as, = e/(L + e). Rearranging, entrainment rate = e = L/(1 - ). At the top tray, e = 0.50(945)/(1 - 0.50) = 945 lbmol/h, which is very excessive. At the bottom tray, e = 0.017(3,351)/(1 - 0.017) = 58 lbmol/h (d) From Eqs. (6-70) and (6-72), the froth height in the downcomer = hdf =(ht + hl + hda) / 0.5 Estimate the head loss for flow under the downcomer from Eq. (6-71). Area for flow under the downcomer apron = Ada = Lwha = 42.5(2 - 0.5) = 6...
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