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AnonymousWe just had a steam-air decoke on our Coker furnace quite recently. However, after the unit was started up, there was siginificant increases of the furnace pass top tube temperatures, and the fouling rates are between 2-3 degrees Celcius per day. Radiant tubes fouling rates are not as bad as the top tubes. Can anyone tell me what is the reason of the high top tube skin temperartures?
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AnonymousWe have documented evidence that mineral deposits remain on the tubes post SAD. Primarily made up of Calcium and silica – and some other minerals. Problem is, these are the key ingredients in insulation. Testing suggests the insulating value to be 5 times that of coke. It will only take a thin layer – this material cannot be burned out. If you want more info I can be contacted at cboase@evereadyindustrial.com
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AnonymousThere could be many reasons but the person who has done steam air decoking knows better. Some of the reasons are given below.
1- Reverse flow of steam and air may not be manitained properly, time wise and ratio wise, may be arch temperature kept low during decoking at forward and reverse flow , may be heater effluent not anayse at reverse flow for complete burning.
2- If decoking has done propery and it has happned during or after start-up, than it could be due to shight foam carry over from coke drums.
3- If it is not due to foam carry over from coke drum, than it could be due to after burning i.e. less flow of combustion air or very minor tube leaks.
4- it also could be due to less velosity steam injection .
Abdul Hakeem ahabid@ yahoo.com
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