5. Conclusion
The liquid weeping as a key element in performance of trays was
investigated by the experiments and CFD model. A bunch of tests were
carried out by the experimental tower in industrial scale where the
experimental tower had two Nye trays and two chimney trays. The area of
holes was 5% (based on total area).
The weeping in outlet and inlet sections of the tray and the total
weeping rate were experimentally determined. It was found that the
weeping rates in the inlet section of the Nye tray are higher compared
to the outlet half of the Nye tray for low liquid flow rates where
weeping rates were greater in outlet half of the Nye tray for middle and
high liquid flow rates. Moreover, the difference between the weeping
rate from downstream and upstream of the Nye tray reduces by increasing
the gas flow rate. Moreover, higher gas rates provide low weeping rates
along with the tray, which may result in increased tray efficiency.
Besides, it was observed that taller weir height increased weeping rate
unless at high liquid rate. Through a limited comparison between Nye
tray and the same sieve tray, it was revealed that weeping rates in the
inlet of the sieve tray were higher compared to the outlet of the sieve
tray. But concerning the Nye tray, weeping rates in the downstream were
very larger rather than those in the upstream. It is noteworthy that
some weep can be endured without noticeably affecting the tray
efficiency. Some mass transfer from and to the weeping liquid happens to
reduce the effect of bypassing on efficiency. Weeping from the exit
section of the tray is not detrimental to tray efficiency to some extent
compared to weeping from the inlet of the tray and is endured to a much
higher level [3]. Regarding this issue, it is demonstrated that the
Nye tray is suitable for operating in high liquid rates where weeping
rates tend toward the outlet half of the Nye tray. Overall, it seems
that the inlet panel of the Nye tray makes a higher capacity for tray
where it leads to very low weeping rates from the inlet of the Nye tray.
This specification is a positive point of Nye tray and may provide high
efficiency compared to a sieve tray.