【Daily Question No. 139】May 19, 2018
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This post was last edited by Green Lotus on 2018-5-19 at 11:23. [Daily Question No. 139] May 19, 2018. Liquid overflow is also known as tower flooding. True or False ( ) Please reply within two days.
Wrong; flooding refers to a condition in a tower where gas-liquid counterflow or liquid-liquid counterflow contact takes place, but counterflow operation cannot be achieved due to excessive flow rates. When the flooding point is reached in a tower with gas-liquid contact, the liquid cannot flow downward smoothly but spreads upward and is carried away in large quantities by the gas. The cause of flooding is an excessive vapor load on the tray. Essentially, the liquid from the previous tray does not have enough time to flow down through the downcomer and the gap between the trays; as a result, liquid accumulates on that tray. Eventually, the liquid also fills the tray above it, and at that point, flooding occurs. After flooding occurs, the pressure at the bottom of the tray increases, making it more difficult for the fluid to flow downward; if the heating is reduced, a full-liquid level will again appear at the bottom of the tower. Measures to prevent flooding are: (1) operate at the specified feed rate ； (2) Operate according to the specified return flow rate.
Error: In a distillation column, when the liquid phase accumulates beyond the available space for various reasons, this phenomenon is known as flooding； During the distillation process, liquid gradually accumulates above a certain tray, eventually filling part of the column section and obstructing the upward flow of gas. This prevents proper mass and heat transfer between the gas and liquid phases, a condition known as column flooding.