6.5.3 Preliminary determination of tower diameter

Tray area. Using an entrainment flooding correlation is the usual method of calculation, but short-cut methods (e.g., Ref. 10) are often adequate. However, to minimize trial and error, the author prefers to perform the preliminary estimate using the flooding correlation which will eventually be used, with some simplifying assumptions. In this example, the Kister and Haas correlation [Eq. (6.12)] will be used for the preliminary determination of tray area. Make the following simplifying assumptions:

Top section

^ * ^ * 3.30V-lg7 2.478 r V 24 5 ft . - °-144(^944-) (2^44) fe) = 0-225ft/s

Bottom section n n iaa/0-52 2.84)0126/ 3.614 \01/24 \ M

CsB = 0144l"27l9T) 127191/ IfcsJ =0231ft/s

Calculate the flood velocity from Eq. (6.9) Top section

Bottom section

To calculate the bubbling area from the flood velocity, the derating factor is needed (Table 6.7). For depropanizers, SF = 0.9 top and bottom. Also needed is a safety margin from flood; at this point, assume the column is to be designed for 80 percent of flood.

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