March 24, 2011 at 10:17 pm #2331
Looking for any experiences with a leak/fire on the feedline connector. Our drum has about 45 mins of feed into it. The fire damaged the hydraulics on the H&C system. Currently have steam going into the drum, considering water next, but worried about hazards when/if we decide to unhead. Looking for any experience in this area, especially with ways to mitigate the risk of unheading. Currently reviewing concerns from the lessons learned following the Anacortes Washington tragedy in the 90’s.
March 24, 2011 at 11:03 pm #5196
Marc – I recommend steaming the drum for at least 12 hours with big steam, then cool with water. Given 45 minutes of feed and a long steam out, you will only need about 15% of your normal water total (since feed that entered is likely less than 10% of normal total; coke yield will be high since coking temperatures are low for first 45 minutes). Concern will be a plugged drain after water cooling- hopefully the extended steaming will reduce or eliminate risk of uncoked resid plugging the inlet distributor or drain line. Worst case you would have to partially open the bottom head (using remote unheading techniques) to drain the water. Hopefully that will not be needed and you will drain via your normal line-up.
Of course, you should not unhead if you cannot get water into the coke drum. In that case you need to try to get steam in and then add water simultaneously. There may be water-hammer issues, but that is acceptable if it allows water to enter the drum. Another option is to add water via the top water line, assuming you have such a connection. Cooling can be validated by determining if steam is being generated as water enters from the top (a rise, even a modest one, in top oulet temperature should be apparent).
We have had success with this technique at our Beaumont and Chalmette-2 Cokers. Best regards – Mitch Moloney
March 24, 2011 at 11:16 pm #5195
Yes, we had tried the same method. We steamed the drum for 24 hours. Then introduce water in and drain it out. Draining would be a good indication on what to expect during unheading. If there is no issue during draining, then unheading the drum should be ok. We took precaution during unheading with operators on pyrosuit. Fortunately, unheading was ok.
March 25, 2011 at 7:52 am #5194
You had already got best advices from Mitch and Coked; at this point try all you can, even holding water and blowing steam through; if you can get steam/water through and able draining through the pipe, then you are in good shape, especially if your is a bottom entry drum without distributor? Normally bottom entry are easily plugged, especially when draining.
ultimately what you are looking for is making sure what ever is in that gets properly cooldown to avoid any hot tar material igniting and causing more damages.
It could be a very serious situation considering the drum may still be full of resid due to very short time into coking; also, you have H&C, which requires further safety precautions during unheading; just be prepared for the worst and hope for the best. Good luck and lets know how did it go
March 25, 2011 at 7:57 am #5193
Forgot to mention being prepared for manual unheading since most likely steam blowout will damage your H&C cylinders and won’t be able to get the head down
March 25, 2011 at 6:05 pm #5192
All good advice from Mitch, Lucky and coked.
Take your time. The longer you steam/quench, the better the chances of not having a fire. Again, take your time.
Let us know how it turns out.
March 31, 2011 at 1:11 pm #5182
Marc, any feedback on this?
Hope it went all well
March 31, 2011 at 10:06 pm #5176
antonio saura CebrianParticipant
Several week ago somebody asked for the same problem I wrote this item
one of the recent accidents in recent years has been for this event of a loss of injection drum (plugged channel), the drum was ketp 5 days with out nothing (steam or water) the operators thought that the drum would be cold, after the accident was estimated that a drum of coke may take 15 to 27 days to cool a temperature below 100 C
when the maintenance staff opened the bottom flange was an explosion, two people died at the bottom of the drum
after this accident we suffer this plugging and based on this experience we apply the following procedure
we inject water from the top (alternate quench) until it had a water level above the bed of coke, as the water enters the water perchlorate and vaporizes
-Foam was injected (via a fire truck) through the top line
-we opened the flanges (we kept a team a group of firefighters around the bottom drum) and proceeded to cut the hole pilot ( speed was 2 to 3 feet per minute ) all the personal was protected (EPP)
Remember that when you open the bottom of the drum (depending on what type of unheading devide you have install) drum will have accumulated hot water , for that reason open partially the drum and let it drain
When for some reason we have been some problem with power, etc(blackout) our procedure if we dont loose the entry to the drum and depending how much hours this drum was in operation (less 6 hours) we inject flushing oil (sometime in the service header there is some conection (in all ours design we have 2″ line) and keep that injection for 5 or 6 hour after that we inject steam for 2 or 3 hour and then we sent to the coke condensate or blowdown system (this take between 1 and 2 day) because you have tarry (vacuumm and coke) and the filter in that system are going to plug and you have to keep cleaning
with this procedure (we did about four time with any safety issue) we dont send any tarry to the pad
April 1, 2011 at 2:51 am #5174
Hope everything went well !
Please share your experience!
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