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This topic contains 5 replies, has 2 voices, and was last updated by  Anonymous 10 years, 3 months ago.

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  • #1831



    recently iam facing problems in our coker.nowadays the switch valve upstream pressure has increased to 5 kg/cm2. normally during and after switch over the pressure earlier was only 3.5 kg/cm2.iam requesting you to kindly advice on this .There was one change we did one is pass flow increased 10 m3/hr,whether is this the reason for more back pressure in heater outlet.


  • #4605


    What was flow rate through furnace prior to 10 m3/hr increase?

  • #4604


    Flow rate was 44 m3/ hour before increase

  • #4603


    10/44 is a 23% increase in flow rate. Pressure drop goes as the square of the flow change, or 1.23 squared = 1.51. That means pressure drop would increase 51%, so your increase from 3.5 kg/cm2 to 5.0 kg/cm2 is not unreasonable, though still higher than expected. A 1.5 kg/cm2 DP increase would mean the DP prior to the rate increase was 3.0 kg/cm2, which only leaves 0.5 kg/cm2 (~7 psig) for coke drum back pressure, which is unreasonably low. Possibly coke has spalled and is creating additional pressure drop in the piping circuit.

  • #4602


    Dear guest

    Thanks for your reply can you please tell me whether can we suspect the. Possibility of a choke or coke formation in between switch valve and feed valve which may also be the reason for back pressure

  • #4601


    Coke can be lodged anywhere in the piping system between furnace and coke drum. Most typically large coke pieces can become stuck in elbows or reductions in piping diameter. Clean out flanges at elbows are usually provided to allow piping inspection during drum cuts or maintenance windows.

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