April 3, 2013 at 8:19 pm #1705
What is the procedure of furnace trip ? Can I try to start again the furnace ? Can I stop the furnace ? How many times Can I Start the coker furnace ? If I try many times I have the risk to fill up part of the coker drum with the furnace “cold” feed. It means the more risk of foaming, decoking problem, increase of coke VCM and safety problems (coke drum opening). So, what would be the procedure ?
June 3, 2013 at 1:27 am #4465
Interrupted feed can result in a very serious safety hazard if not handled properly. It can also become a significant operational problem even if the safety hazards are mitigated. Each company should have interrupted drum procedures. Depending on where the drum is in the fill cycle, feed has been successfully re-introduced into a partial drum. There are operational hazards and you can aggravate the potential safety hazards by putting feed back into the drum.
There have been a number of presentations over the years given at Coking.com conferences that have highlighted the potential foam over problem with putting feed back into a partially filled drum. There have also been presentations over the safety hazards of a tarry drum. Equilon Anacortes had six people fatally injured from a tarry drum that was not cooled before the heads were removed.
The conclusion from the Anacortes incident was that water should be used to cool the coke drum before removing the heads. If the normal way of adding water to the drum is not available, some other method is needed to remove the heat from the contents of the drum before removing the top and bottom heads as the drum will not cool to a safe value without actively removing the heat.
The more low temperature feed barrels that are put into the coke drum, the higher the potential hazard from a foam over or tarry drum standpoint. Setting a limit of the maximum number of low temperature feed bbls that can enter the drum before bypassing is something each company should do to prevent severe operational or safety hazards.
July 8, 2013 at 2:56 am #4442
Give me some more information. How you respond to a furnace trip depends on a lot of factors. How long is the furnace down? How long have you been in the coke drum? Did you lose flow into the coke drum? How cold did the coke drum outlet temperature get? All these things factor into the response to a furnace trip. You need to respond differently based on looking at all these factors. The main thing is to try to keep flow into the coke drum on a furnace trip. Upon a furnace trip our control system sweeps the passes with steam into the coke drum. This keeps the channels in the coke bed open. The next thing we would look at is how long has the drum been coking. If it is late in the cycle we would not reintroduce feed, but prepare the drum for decoking as normal. We would put the furnace into bypass, or swing feed into the sister drum if it is available, and then bring up the furnace. If it is in the early/middle of the coking cycle we would look at coke drum outlet temperature as a determining factor as to whether or not to reintroduce feed. A cold drum outlet temperature will create foaming issues with the reintroduction of feed. If we can get the furnace back up before the coke drum outlet temperature gets too cold then we would restart feed at a lower rate, (to extend the coking time) raise our furnace outlet temperatures and finish filling the drum.
Hope this helps,
July 24, 2013 at 1:25 am #4439
it all depends at what stage of the coke drum the heater has tripped . if the heater trips says after 5 -6 hrs after taking the coke drum inline then you can continue with the cold feed till the heater is back in service not more than 1-1.5 hrs from time of donw of the heater
After heater is taken in line can fill the drum with COT at 1-2 degree higher than the normal operating temperature
July 24, 2013 at 1:36 am #4438
if the furnace trips 4-5 hrs of the switch over of the coke drum then you can restart the heater but not later than 1-1.5 hrs, you need to ensure that the rest of the cycle the COT is maintained 1-2 deg C above the normal operating temperature. this will take care of the deheading problem and the VCM content in the coke. if the heater could not be started within in the above time it is better bypass the block
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