• We are having problems with the volatile material in the carbon of the DCU. To lower the MV we have increased the temperature of the furnace, and increased the steam flow during the vaporization of the bed; any other recommendations for this?



  • Ezzat Fouad, ERC, EFouad@ercegypt.com

    Typically the hereunder process variables are affecting the volatile combustible matters (VCM) in the coke:

    1: Heater coil outlet temp (COT): The higher the COT, the lower the VCM in coke produced. COT is preferred to be in the range of 495 to 500 C.

    2: Coke drum overhead pressure: The lower the overhead pressure, the lower the VCM in coke produced.

    3: The distillate/naphtha recycle ratio: The higher the distillate/recycle ratio, the lower the VCM in coke produced.

    4: The coking cycle time: The longer the cycle time, the lower the VCM in coke produced.

    5: The steaming out flow rate: The higher the steaming out rate, the lower the VCM in coke produced.



  • Marcio Wagner Silva, Petrobras, marciows@petrobras.com.br

    The unit is using a motorized ball valve as switch valve? In this case, it's common to use many steam purge lines to avoid coke deposition over the  seal faces of the valve and then it's necessary to evaluate and monitor the steam purges procedure to avoid a excessive decrease in the feed stream temperature to the reactors which can lead a high volatile matter in the produced green coke.