Internal structure of the distillation tower
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Why is the overflow height on the tray of a distillation column set so high according to the design? What is the principle behind this? Is the resistance too high, causing the tray to tip over easily?
This is what you feel, and it doesn’t necessarily mean it’s wrong. ;P
A distillation tower requires a clean tower – entering it in such fancy attire, along with those dirty shoes that look like bear paws. From a safety perspective, is this tower oil-free and free of debris???? Then, the liquid layer thickness of this tower is designed based on the characteristics of the gas rising from its base. Factors such as the liquid density on the tray, the resistance encountered by the upward airflow as it passes through the liquid layer, and the resulting ideal washing efficiency. Does this tray look like a floating valve tray? I haven’t seen it; please advise.
Typical floating valve trays; the most common shapes for floating valves are circular and rectangular. As for the requirements regarding cleanliness, they aren’t that high either. After initial installation or maintenance, it needs to be washed with water and purged with steam; as long as there are no large debris, tools, iron pieces, or stones inside, there will be no problems. We also wear this equipment when performing tower tray maintenance, disassembly, and welding work. But for distillation towers in certain fine chemical or pharmaceutical industries where high cleanliness standards are required, the company certainly won’t allow them to enter in that way.
Based on their location, they are divided into inlet weirs and outlet weirs: The inlet weir is a flat liquid receiving plate that ensures a liquid seal in the downcomer, allows the liquid to flow evenly into the lower trays, and reduces the impact of the liquid flow in the horizontal direction; it is located at the end where the liquid flow enters. Outlet weir – maintains the liquid level on the tray and ensures uniform distribution of the fluid. The maximum overflow rate at the outlet weir is < 100–130 m3/(h·m). Determine the length of the outlet weir. Single-flow tray – outlet weir length Lw = (0.6～0.8)Di, where Di is the inner diameter of the tower ； Double-flow tray – outlet weir length Lw = (0.5～0.7)Di. The height of the outlet weir, hw, is determined by factors such as the properties of the material, the type of tower, the liquid flow rate, and the pressure drop across the tray.
The resistance should have been calculated! Is the load too high?