Hi
I need to calculate the flooding factor of a distillation column. Usually the fooding factor is calculated and reported as the average of the flooding factors on the distillate and bottom of the distillation column.
The equation for the flooding factor is:
F=u * (rho vap)^0.5
where u is superficial velocity of the vapor and rho vap is the density of the vapor.
Now, my question is which streams should I consider in the distillation column for the calculation of flooding factor? As we know there is feed stream (input), boilup stream, outlet from the bottom, outlet from the top (vapor phase), and reflux stream.
So, if we want to calculate the flooding factor, should we estimate the amount of vapor in the bottom (the boilup flow) and calculate the velocity and density of the vapor based on that? and for the top of the column, is it the amount of vapor going out which should be conidered for velocity and vapor phase calculation?
-The boil up flow
Attach are two link which can help you answer your question.
http://eleceng.dit.ie/gavin/Distillation/Column%20Design.pdf
seperationtechnology.com/distillation-column-tray-selection-1
Column flooding can be caused by excessive vapor or liquid flows in the column. As a general rule, one should perform flooding calculations in any column section that has a different vapor and liquid loading.
The manufacturer of the column packing and internals should be able to assist you with more accurate calculations for these.
I should also state that there are a number of factors that can affect column flooding and please keep in mind that your equation above is highly simplified. More accurate equations take into effect other factors such as viscosity and surface tension. In addition, if you have any other adverse factors such as foaming, things become much more complex.
Furthermore, virtually all of these calculations assume "Steady State" conditions which do not take into effect startup, shutdown, variations in composition, flow, heating, or cooling.
Hi Saeed,
There are various correlations regrading flooding factor including Kister-Hass (Ref: BOOK distillation design by Kister). I strongly recommend to use AspenPlus (RadFract distillation column / sheet hydraulic ) to estimate it.
Best, Mahdieh
This is an old thread and this is a place to share information, and I enjoyed the answers from all three people above. If you like to give better advices, please welcome. If you like to read and follow, please do. But, you are not allowed to give negative comments-commands. This is inappropriate.
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