Problems in simulating the flooding process in distillation columns

More information on flooding falls under the scope of chemical engineering principles; it is recommended to consult university textbooks or any manual on tower calculations, as this will provide satisfactory answers. As for setting the opening ratio, one can refer to Aspen’s help documentation or explore the various options available in the software.

I mainly want to know that if we use Aspen to calculate the flooding point by changing the flow rates of the gas and liquid phases, has anyone done this before? Could you share your approach?

I have also been learning about this area recently; through traditional load performance charts, it is possible to see quite clearly the impact of gas-liquid changes on flooding. The section on \"Gas-liquid mass transfer equipment\" in the Chemical Engineering Handbook provides detailed analysis methods.

Foam flooding in towers occurs in two scenarios. One is foam entrainment flooding, which refers to a sudden increase in the tower’s pressure drop due to excessive foam entrainment on the tray surfaces; this is usually caused by an overly high gas load within the tower. Of course, it is related to various parameters such as the tray spacing, the liquid layer height on the trays, and the foaming properties of the liquid phase； Another type of flooding is downcomer flooding; in simple terms, it occurs when the liquid load inside the tower is too high, and the flow area of the downcomers is too small or the flow resistance is too great, preventing the liquid from flowing downward smoothly and thus leading to a \"flooded tower.\" There are many factors that can cause this type of flooding, including the spacing between trays, the cross-sectional area of the downcomers, the clearance at the bottom of the downcomers, the pressure drop across the trays, and the foaming properties of the liquid phase. These two types of flooding can occur simultaneously or only one of them. Regarding their calculations, as LTY friend said, they can be found in various manuals and textbooks. As for LZ’s desire to use the distillation column hydraulics built into ASPEN for the calculations, I am not in favor of it; the reason is simple: the errors are too large. My online username is “fandian” – which means the inflection point on a liquid level curve. When the Internet first emerged, over a decade ago, I was working on collecting data regarding the inflection points of new types of trays, and that’s why I’ve been using this username for over a decade now, hehe! I suggest to the original poster that, if it’s purely for research purposes, it would be a good idea to learn more about this area; everyone can exchange ideas if there are any questions ； If the goal is to address the actual bottlenecks in a factory, it’s better to turn to professional manufacturers of tower internals for help. It’s not that we don’t trust your expertise; experience is indeed very important when dealing with practical problems. (It’s not about making a profit here – I’ve been in this field for several years now, haha.) ； If it’s to learn *ASPEN, read the help files carefully; the meaning of each item is explained there.

It’s rare to encounter an expert in this field, so I have a question: In many countries, the dot distribution curves for fillers are plotted with the F-factor as the horizontal axis, while in China other correlation factors seem to be used; at least, the F-factor isn’t mentioned in textbooks on chemical engineering principles. What is the reason for this? Which one is better? What kind of horizontal axis did you use over a decade ago?

Fandian is probably more experienced; I hope he can give me more guidance in the future. The previous question was to see if Aspen could be used to solve some problems in production. I originally wanted to perform hydraulic calculations on a tray; I found some relevant formulas online as well, but the errors were quite large. It seems that, as you said, if the goal is to address the actual bottlenecks in the factory, it’s better to turn to professional patent holders of tower internals for help. Experience is indeed very important in practical problems.

I’ve been looking into this topic recently, and here’s my opinion: Textbooks focus on universality, while filler manuals emphasize specific properties; moreover, the universal correlation factors are all derived by foreigners through regression analysis. Our company’s hydraulic calculation software relies mostly on correlation empirical formulas for calculations, and sometimes certain parameters are modified and refined specifically. It’s hard to say which method is better, as the correlation charts using the F-factor as the horizontal axis, as well as the experimental systems underlying those formulas, are often not those used in actual applications. Therefore, in practice, the determination of equipment size relies more on engineering experience. This post was last edited by LTY on 2008-5-21 12:46.]

Packed towers generally use the empty tower kinetic energy factor F

The experts upstairs are all truly skilled. I would like to ask how to use ASPEN to perform these calculations, and also in which module one should estimate the equipment dimensions Not very grateful

In fact, there are more than one type of diagram; specialized bulk packing software uses diagrams that are different from the load diagrams we usually see. Unfortunately, I can’t upload files, otherwise I could send one to you for viewing.

I want to know how to use Aspen to calculate the mist entrainment in towers; why hasn’t anyone talked about this? I don’t know how to use Aspen