The problem of flooding

Generally speaking, the reasons for flooding include the empty tower velocity of the gas in the tower, the flow rates of the gas and liquid phases as well as their physical properties, and the structure of the tray system, especially the tray spacing; it cannot be determined simply based on the type of tower. There are many posts on the forum discussing this issue; a few are listed below for reference. http://bbs.hcbbs.com/viewthread.php?tid=396406 (What is meant by flooding?) http://bbs.hcbbs.com/viewthread.php?tid=344951 (Operation of distillation columns – What are the causes of flooding, and how to deal with it?) http://bbs.hcbbs.com/thread-265742-1-1.html (Flooding in distillation columns)

1. Liquid flooding is also known as tower flooding. It is an abnormal phenomenon that occurs during operation with overflow trays; it significantly reduces the efficiency of the trays, causes fluctuations in column pressure, and leads to poor product separation. This is manifested as an increase in the liquid level inside the downcomer and an elevation of the foam layer on the tray, resulting in the liquid flow between the trays becoming connected. The cause of flooding is an excessive liquid load, an insufficient gas load, or too small a downcomer area. To prevent flooding, during design and production it is necessary to calculate the liquid layer height required for one tray as well as the foam height on the tray, in order to verify the selected tray spacing; additionally, the residence time of the liquid in the downcomer and the capacity of the downcomer must be determined. 2. The main causes of flooding are: the steam velocity in the tower exceeding the flooding velocity, as well as blockages in the downcomers of the tray, which prevent the liquid from flowing back to the lower trays and thus lead to flooding of the tower.

Foaming and tower flooding are two different concepts. The explanation upstairs is incorrect.

Although the two concepts are different, they are in a sequential relationship. A flooded tower is a severe case of liquid flooding.

If flooding occurs due to an excessive amount of liquid, which leads to a significant drop in gas pressure and ultimately prevents effective penetration through the liquid layer to achieve sufficient mass and heat transfer, then the same can happen in your packed tower as well. If the amount of liquid is too large, the liquid layer on the surface of the packing will also thicken, which obviously leads to a decrease in the efficiency of gas mass and heat transfer. However, it’s hard to say whether this will result in the tower being flooded – how much liquid is needed for that to happen?