Home › Forums › Coking › Technical › Heaters & Furnaces › Function of Main column bottom filter
This topic contains 6 replies, has 2 voices, and was last updated by Anonymous 14 years, 7 months ago.
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May 16, 2007 at 9:59 am #4011
AnonymousWe install a filter in the main column bottom circulation loop.
Recently we found the inlet line of the filter is plugged.
We can not shut down our plant due to the abnormal event.
We would like to know how long we can run our plant without this filter. -
June 10, 2007 at 2:48 am #7380
Anonymousthis happened to us in lake charles, we ran until the next t/a and revised the nozzle in the bottom of frac
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June 11, 2007 at 8:35 am #7379
Generally when the people design this system they conceived to operate one week without them and for that reason this system only have one pump installed in the field (commonly)
If the operation of the unit is stable and during the switch of the drums and stripping you dont send too many coke to the bottom of the fraccionator, this would avoid that the coke strainer (inside of the fract ) in the suction line to the heater pump, begin to plugg with coke, in other words; while you don’t see any problems by the NPSH of the pumps you can kept operative the unit
We have had this problem of plugging due to the emergency valve (butterfly) in this line . Since if you observe these valves internally a line of 6 inches It turns in o almost of 3 inches due to the internal configuration
We running the unit monitoring the pressure in the suction and realizing thermography to the wall of the fraccionator, in order to seeing the level of coke until I stop the unit for his repair (around 3 months) -
July 9, 2007 at 4:41 am #7345
AnonymousHave you tried steaming back up into the tower to unplug the line? Make sure that you dry the steam out real good before trying this!
How long you can run depends on how tall the stand-pipe to your furnace charge pump is and how much coke you are carrying over in your daily switch/ blowdown -
July 11, 2007 at 11:49 pm #7341
AnonymousOur nozzle from the frac to the strainer is only a 3″. We realized during the first 2 years of operating this thing, that the nozzle was plugging in the bottom of the frac. The nozzle is too small and also has a vortex breaker thereby contributing to bridging of the coke. We do not even use the strainer loop and have blinded it off. We run about 18 months between turnarounds and typically see about 4′ of coke in the bottom of the frac, which is well below the height of our standpipe.
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June 14, 2008 at 6:25 pm #6789
AnonymousTry back flushing with heavy coker gas oil. It produced better result then steam flushing. In steam flushing there is always a chance that the heater charge pump might loose suction. Back flushing can be done when the unit is online i.e. with out bypassing the reactors.
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June 18, 2008 at 12:31 pm #6777
AnonymousStupid question. Have you tried to blow it back into the column with steam? And I question the safety of performing that task as it could potentially cause problems with your bottoms pump if you sluff off a big chunk of coke. I would guess a six month window. . .but guessing is exactly all you can do. You could proactively reduce charge rate and reduce the amount that you fill the drum so as to reduce the amount of particles entrained. Or, you could reduce cycle time at the same charge rate to reduce the amount the drum is filled. Perhaps these options could buy you more time.
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