Distillation column simulation: theoretical number of plates, actual number of plates, plate efficiency
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I have a question for the experts here: The image in the attachment shows the parameter input interface for simulating a distillation column using ASPEN. I would like to know whether the values for the tray numbers are correct Note: This distillation column is already in use, and its structural parameters are known (it has 65 trays, excluding the condenser and reboiler). Therefore, I believe the actual number of trays (including the condenser and reboiler) is 67; hence, I entered 67 in the parameter input field ； It is also necessary to enter the value of the tray efficiency. What is the difference between the theoretical number of plates and the actual number of plates?
The actual number of plates is obtained by dividing the theoretical number of plates by the efficiency of each actual plate; thus, the actual number of plates is 65. It is necessary to determine the efficiency of these actual plates, and once that is known, the theoretical number of plates can be calculated. Both the top condenser and the bottom reboiler can be considered as one theoretical plate each. Simply use the information available and apply a straightforward input method based on that information
The specific efficiency is related to both the distillation purpose and the distillation system. For conventional distillation, the efficiency is 60% to 100%. Used for absorption, with an efficiency of 80%–100%. However, for systems prone to foaming, the efficiency is very low, below 50%. You need to consider it based on your own field of study. Based on previous production experience.
In Aspen, the value entered represents the theoretical number of plates; the efficiency is set at 100% by default. In practice, it’s around 60 or so. In the software, the value entered must be less than the actual number of plates, and the efficiency can be used to make the conversion