3 replies to this topic

[Root]

Hi,
Can any one put some light on distillation column bubble cap tray leakage?, what is the main reason and how this problem can be solved during normal operation.
Thanks

[AHT]

Could you please give more details bout your system? (fluid handled, operating pressure&temperature)

Have this problem been there since the column started-up, or was something that appeared just recently?

Bubble cap trays are not supposed to leak. In fact, they are now-days selected almost exclusively for extremely high turndown applications, or when leakage must be eliminated

[Root]

Could you please give more details bout your system? (fluid handled, operating pressure&temperature)

Have this problem been there since the column started-up, or was something that appeared just recently?

Bubble cap trays are not supposed to leak. In fact, they are now-days selected almost exclusively for extremely high turndown applications, or when leakage must be eliminated

Hi AHT,

The column pressure is 3.7barg and temp 166^0C, Problem was noticed since plant started after shutdown. by the way tray can leak in valve type trays also or not?
Thanks

[AHT]

Toor:

Do you mean "tray weeping" (liquid coming down through the tray perforations at low vapour flows) or leaking through the tray joints?

Bubble cap trays (BCT( should not leak. Let me quote some paragraphs of one of the best book about distillation ("Distillation Operation") by Henry Kister:

"The main current us of BCT's is for minimising tray leakage or achieving high turn-down. In either case, BCT joints must be leak-tight if the tray is to achieve itsobjectives...Minimising tray leakage is also important on liquid outlet pans and chimney trays, especially when used for total draw-off". To prevent or minimise BCT leakage, it is essential to pack its joints with gasket materials...A joint whose gaskets deteriorated during service may leak a lot more than a non-gasketed joint. Gasket deterioration may be caused by mechanical wear (e. g., due to thermal expansion) or by chemical attack"

The only other possibility I can think of is solids accumulating under the caps, which prevent them from closing properly. Fouling could be caused by corrosion, polymerisation, cracking, solids forming at high temperatures, or thermal decomposition.



Valve trays are known to leak (or I should rather say "weep") under certain conditions.

Could you please give more details bout your system? (fluid handled, operating pressure&temperature)

Have this problem been there since the column started-up, or was something that appeared just recently?

Bubble cap trays are not supposed to leak. In fact, they are now-days selected almost exclusively for extremely high turndown applications, or when leakage must be eliminated

Hi AHT,

The column pressure is 3.7barg and temp 166^0C, Problem was noticed since plant started after shutdown. by the way tray can leak in valve type trays also or not?
Thanks