Column flooding. How is it caused?

[Harley]

Hi guys,

The ultimate question here is: What causes column flooding and how can it be fixed?

1. How and why does the ABV of the boiler charge affect this?
2. How and why does the column design affect this? Consider height:diameter ratio, packing material, packing density and forced reflux.
3. How and why does the boiler energy input affect this?

If there's any other questions that I should be asking then please add them. Thanks in advance for the insights!