Quench water draining

[Freddy Martinez]

Has anyone experienced quench water draining so fast from the drum that actually air is sucked in through the depressurization vent line?  Is this a common occurence?

[Anonymous]

Peak quench water drain rate is a function of drain piping hydraulics, coke bed pressure drop, static head of water in the coke drum, and coke drum pressure during draining.  Air has to be sucked in through the depressurization vent line to prevent vacuum condition in the coke drum.

[Anonymous]

How often does this happen, have a lot of people experienced this?  I think most of the times drums are under positive pressure from the steam generated by the hot coke in contact with quench water until pressure drops to ambient following atmospheric venting.

[Lucibar Davalillo]

I have not heard many having such problem; of course, it may happen due to different reasons; poor vent design may be one, but it would have to happen for every single drum, rather than an isolated case; others come to my mind are followings:
i) isolation valves at psv inadvertely left open or large leaks, ii) very rear long enough coke bed chanelling, which would evident if lot clean cold water is being drained, iii) if slides valves installed, opening too fast and draining through it; iv) almost forgot the possibility of starting draining at very low pressure due to: a) blowdown drum vapors line up to flare, b) blowdown vapors recovered by ejectors or ring compressors, in order to meet new environmental regulations set by NSPS CFR 60 Subpart Ja, which establishes lowering drum pressure below 5 psig before venting.
 
Is there any coker following such regulation (believe applies for new construction since May 2007 ?
 
   

[Anonymous]

First, there is a problem that air going inside the drum?, if the question is because  to the vacuum in the drum?
There are units where before to be  drain (after soaking time) they  remove the flange top (during this time nobody is around the drum
which is your concern?

[Author]

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