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high coker furnace top tube skin temperatures after steam-air decoke

Home Forums Coking Maintenance Steam air decoking high coker furnace top tube skin temperatures after steam-air decoke

This topic contains 2 replies, has 1 voice, and was last updated by  Anonymous 16 years, 10 months ago.

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  • #4230


    We 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?

  • #7622


    We 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

  • #7548


     There 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@

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