water hammer when transitioning from steam to water

[Anonymous]

While introducing water to cool the drum, we currently have a practice of intentionally throttling steam so as to cause violent water hammering of the drum inlet line. This is ostensibly done to keep the drum inlet “open” and to keep coke from backing into either the inlet line or plugging of the inlet “hat” ( a slotted cap on the drum bottom flange that sits above the inlet line). Is this a common practice anywhere else?  I am concerned that this hammering will damage inlet piping and joints.

[Claus GrafParticipant]

….so as to cause violent water hammering of the drum inlet line…..
 
This does not sound like a good idea.
 
Your inlet line should be clean after the steamout to fractionator & blowdown.
 
Do you inject steam before the drum switch ?
 
Since you have a “hat”, I  guess that you remove the bottom head (manually or remotely) to remove the coke from the drum. You should be able to inspect it to see if it is plugged.
 
Regards,
 
CG

[Anonymous]

This is a common practice at one Coker I worked before. You can remove the “hat” if you wish

[Anonymous]

Yes, drum is steamed for 30min-1hr before water introduction.  Inlet can be checked when head is removed  but by then it is too late. Potential pluggage will prevent or delay water draining.

[antonio saura CebrianParticipant]

I think that you have to work with the procedure of steaming, if you remove the hat from the flange bottom be sure you improve the flushing of the feed line before this line is in service,  because some time this line are going to plugging with coke

[Anonymous]

We steam strip for one hour at 12k steam, then cut the rate back to 6k to keep the inlet clear while we depressure the drum.   After we depresure the drum to a suitable drum pressure we introduce water.  When we do this “water check” we open the control valve wide open until we get over 1kgpm introduced to ensure that inlet is clear, we then cut the rate back to minimum.

[Author]

Posts