April 9, 2012 at 4:03 pm #1882
Our refinery has a FW design coker with top/bottom delta valves and a 90 deg side entry inlet. Our operating procedure states that we are to:
[quote]”…..1) steam purge at 20,000 #/hr for 35 minutes and then 2) reduce our steam quench to 5,000#/hr. 3) Let the quench water flow start into the drum until water hammer starts. When the quench water control valve begins to open start backing out the quench steam. (Water hammer is normal and should not harm anything. It will subside once the quench steam is closed. The two flows must be maintained momentarily to ensure the “blowhole” does not collapse. )…..[/quote]”
The problem I am having is the “normal” water hammer has caused valve bonnet gaskets to fail in our steam quench system.
Questions: 1) Is inducing water hammer really “normal” when performing the steam quench-to-water quench transition. 2) I understand the side entry nozzle causes a non-uniform coke formation in the drum (one of the negatives to our Delta Valve designed drum system). Is this the reason for the loss of a “blowhole” concern or is there another reason? 3) Has anyone else had a similar problem? If so, have you fixed it and how?
May 1, 2012 at 2:42 pm #4637
Think of it like a NASCAR race. All cars have 4 tires, an engine, seat belts, a driver and a pit crew. Do they all come into pit lane exactly at the same time to change tires, and fill up with the same amount of fuel? No.
You need to figure out what works best for your coker. I believe there is a greater risk of plugging during the coke drum switch (thats why you start injecting steam before the switch).
Your coker should have quench water flow meter(s). I would try lowering that 5000#/hr when starting the water flow, keeping an eye on the water flow meter, so that there is always water going into the drum.
Anybody in this forum wants to help tim by sharing their ideas/experience?
May 1, 2012 at 5:24 pm #4634
Thank you. We will give that a try. Has anyone automated the process to reduce the risk?
January 1, 2021 at 2:43 am #32022
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