sieve trays

[picasa]

What is the definition of foam derating factor for a sieve tray?
What is HCBN ? It is some sort of fluid name in a stabilizer vessel. I dont know what HCBN stands for.
For a sieve tray what does the ratio "Hole Area / Bubbling Area" stand for?

 

[Guidoo]

picasa:

My recommendation is to post this in the Chemical Process Engineering forum.