To column control, in contrast to column design, tray hold-up and dependenc
ies of tray hold-up on the operating conditions play an important role. The
essence of this article is the development of an improved model of tray hy
draulics over a broad operating range and its experimental validation by me
ans of batch distillation. First, the column dynamics are related to tray c
olumn design parameters and operating conditions. The model parameters are
fitted by column residence time measurements. Two tray load regimes are dis
tinguished: an aeration regime and an obstruction regime. At low column loa
d a vapour increase will decrease the tray mass since the liquid is driven
out by larger aeration. At high load the opposite is the case, since the li
quid is driven up by stowage. The resulting dynamic behaviour is studied by
linearising the rigorous tray model in an operating point. Especially the
influence of the vapour flow on the column dynamics is investigated. For th
e influence of the tray composition change on the molar mass, a new composi
tion-shift parameter kappa is defined. The influence appeared to be small.
(C) 1998 Elsevier Science Ltd. All rights reserved.