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Heater Outlet Temperature Settings

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This topic contains 4 replies, has 3 voices, and was last updated by  coked 12 years, 6 months ago.

  • Author
  • #3852


    We currenty run our coker heaters with a single outlet temperature setpoint.  This ranges between 912 and 918 deg F depending on coke quality and foaming.  We are considering running with a lower heater outlet temperature during the middle of the coking cycle in an attempt to reduce fuel gas usage.  Does anyone currently run at various heater outlet temperatures during the coking cycle?  Does anyone control their heater outlet temperatures at temperatures below 912 deg F?  Is there a lower temperature limit that should be maintained?

  • #7047


    we had run at 910F before due to high skin temperature (towards end of run). We normally run higher COT at start of run and gradually reduce it towards end of run to sustain furnace operation. however, we keep monitoring our vcm and coke quality.

  • #6259


    One of the problems encountered in refinery-fire heaters is an imbalance in the heat flux in the individual heater passes. The imbalance can cause high coke formation rates and high tubes metal temperature, which reduce a units capacity and can cause premature failure. Coke formation on the inside of the heater tubes reduces the heat transfer through the tubes, which cause localized heat transfer through the tubes, which leads to the reduced capacity.

    With a correct temperature distribution you can reduce the fuel gas. The BOILERWATCH MMPII, Acoustic Pyrometer provides highly accurate temperature measurement of heat exchange and heat transfer performance; and allows monitoring of gas temperature conditions, and alerts plant operators concerning impending failures, reducing the frequency of unplanned shutdowns and Coke formation.

    Please visit

  • #5944


    In reference to the heater outlet temperature that one can successfully meet the vcm spec. etc. on the contents of the drum.  Please be aware that these temperature transmitters can read false.  Thermowells do coke as run length’s are increased.  Please monitor the temperature of the drum feed @ the switch valve & the unquenched vapor line temperature.  This will give additional indicators to allow for the reduction in fuel gas you are speaking of.  It may be that you thermo-wells on the outlet of your heater tube is partially coked thus giving a false reading.  I would also look at your recycle rate & percentage of ligher material in your feed.  Remember “heat of vaporization” is endothermic and increases the duty on the charge heater.  Hope this helps.

  • #5539

    Nor Syamrin Wagirin

    we run the furnace outlet temperature at 910F earlier in the cycle, within 1hr after drum switching, to avoid too much firing in the furnace. our coker is a two drum coker, which we experienced some temperature swing during drum switching, causing the furnace inlet temperature to drop. As the coke drum heats up, the furnace COT is increased to its normal operating temperature of 920F.

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