Nonuniform weeping

Under some conditions, vapor velocity maldistribution induced by hydraulic gradient nr tray tilt cam lead to excessive nonuniform weeping (183a Also, see Secs. 6.2.12, 6.2.13). Such excessive weeping can be detrimental to tray efficiency. 

Tests by Lockett and Banik (loc. cit.) show that weeping is often nonuniform, with some hydraulic conditions favoring weeping from the tray inlet and others from the tray outlet. Weeping from the tray inlet is particularly detrimental to tray efficiency because the weeping liquid bypasses two trays. 

Tests by Banik (72) and Zhang et al. (70) show that weeping from valve trays is nonuniform. In Banik s 4 ft x 2 ft rectangular simulator, most of the weep issued from the inlet half of the tray at low liquid rates (< 3 gpm/in of outlet weir) and from the outlet half of the tray ax high liquid rates (>10 gpm/in of outlet weir). The nonuniformity appeared to escalate as weir height increased. This pattern of nonuniformity is similar to that observed by Banik and Lockett (56) on sieve trays. In Zhang et al. s (70) 5 ft x 1 ft rectangular simulator. 

A hmitation of the minimum gas load is set either by weeping of liquid through the openings in the tray or by nonuniform gas flow throngh these openings. The condition for nniform gas flow through the holes of a sieve tray is according to (Mers-mann 1963) ... 

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