Double overflow tray and single overflow tray
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What are the characteristics of double overflow trays? What are the characteristics of a single overflow tray? What are their selection criteria?
This should be related only to the diameter of the tower.
It is mainly determined by the tower diameter; those with a larger diameter use double-overflow weir trays
Our company has newly built atmospheric pressure columns, some of which have dual overflow systems while others have single overflow systems. Is this related to the load on the liquid phase, or is there some other reason? Moreover, gas-liquid phase impermeable trays are installed between the extraction and return trays in the double overflow tray column, as well as at the oil collection tank’s extraction and return positions. Could you help me analyze the reasons?
Double overflow trays are commonly used in large towers with high processing capacities and a diameter of over two meters.
The liquid layer height above the weir is too low → the liquid is not distributed evenly across the weir, which affects the mass transfer efficiency. In design, hOW should be ≥6 mm; if this value is not met, a serrated weir should be used. The liquid layer height on the weir is too high → this increases the pressure drop across the tray as well as the amount of liquid mist carried away; when hOW is ≥60~70 mm, a double-overflow weir should be used instead.