The Effect of Outlet Weir Height on Sieve Tray Performance

The effect of the outlet weir height on sieve tray performance is described in this paper. The studies were made to investigate the effect of the outlet weir height on sieve tray mass transfer efficiency and hydraulic performance. Tests were conducted in the 1.22 m diameter section of the Fractionation Research, Inc. (FRI) low-pressure column. Sieve trays with nominal hole areas of 14%, 13%, and 8% of the bubbling area and hole diameters of 12.7 mm were used. The weir heights used were 0, 25, 51, and 102 mm, with operating pressures ranging from deep vacuum with ortho/para xylene (o/p Xylene) at approximately 20 mmHg absolute to 11.38 bar with isobutane/n-butane (iC4/nC4). A third system, cyclo-hexane/n-heptane (C6/C7) at 0.276 bar and 1.65 bar was also used. Experimental results, including tray capacity, mass transfer efficiency, pressure drop, and entrainment are presented and discussed. The results indicate that the effect of weir height very much depends on the system properties and open area.