Perforated Plate Weeping

Abstract

The mechanism of weeping of a single hole of a perforated plate has been studied in order to improve the correlations for its lower limit of good performance. In perforated plates there are two different types of oscillations: one exists for all gas flow rates including very low ones and has frequencies of 3–4 cycles/sec; the other appears only at high gas flow rates and involves the whole gas—liquid mixture, which oscillates transversely on the plates with a wavelength equal to twice the plate width. These fluctuations affect plate weeping, which is due to the instantaneous predominance of the hydrostatic head h L over the gas pressure drop plus a surface tension term. Because of the oscillations of the liquid and gas pressures, in order to guarantee absence of weeping at all times, the average gas pressure drop must be greater than the maximum value of h L by an amount equal to its oscillation amplitude. On this hypothesis it is possible to consider plate weeping as a function of total submergence.