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Drum Hot spot

Home Forums Coking Operations Cutting, Drilling, Unheading Unheading Drum Hot spot

This topic contains 6 replies, has 4 voices, and was last updated by  coked 11 years, 9 months ago.

  • Author
  • #2396

    Freddy Martinez

    After we installed in this year a automatic bottom unheading we are having a lot of drum hot spot. Is there any correlaction ? How can I reduce hot spot ? What do I need to check ? Regards

  • #5297


    im sure you would have changed your entry to side entry. Was it a single or dual entry? There have been cases where quenching was not sufficient in single side entry.

  • #5296


    in addition to what Mr Coker says, which is the cooling ramp that you use, Do you let the drum for some time to soak

  • #5294

    Claus Graf

    Your Delayed Coker Licensor should provide the recommended (proprietary & confidential) quenching rate.

  • #5293


    Yes, We have one side feed entry with angle of +/- 45 degre related with the drum. We have a quench ramp and in the end we leave 2 hours of soak. We still have a lot of hot spot. Is it common with others DCU ? What is it the solution ? Regards

  • #5291

    How fast the water level dissappeared in the level detectors during the soaking time?, because this give to you how hot is the drum, also the steam or temperature of the water drained from the drum

    It is very important to note that even a normally cooled coke drum can and will have hot spots throughout the coke bed that are detectable during hydraulic decoking. As the drilling water comes in contact with the hot spot, a large eruption of steam and vapors are emitted from out of the top and bottom heads of the drum. In some cases coke erupts from out of the top of the coke drum and onto the cutting deck. Further, some hot spots encountered during the drum cut result in coke falling out of the coke drum into the coke pad glowing and on-fire but in most cases this does not represent a hazard since the cutting water rapidly cools the extremely hot coke. Hot spots in a normally cooled coke drum are caused by the water channeling through the coke bed during coke drum cooling. Cooling water takes the path of least resistance, which in the case of a coke bed are the paths formed by the channels produced in the bed during charging and steaming of the drum. If the water is put into the coke drum too rapidly during the first hours of cooling, then the water will have a tendency to follow the path of the channels and end up on top of the coke bed rather than contacting and soaking into the bed. Thus, it is very important to follow the prescribed rates of water over specific time periods listed in the normal coke drum operating procedures during drum cooling in order to get proper contacting and soaking of the bed to avoid channeling. Delayed Coking Units that produce shot coke often have serious problems with hot spots and coke eruptions since the shot coke is more impervious to water than sponge coke. Additionally, there is also more of a tendency for water to channel through a shot coke bed, and for the shot coke drum inlet to plug during cooling and draining.

    how fast the operator cut the pilot hole? how is the velocity 3 ft/min?

    best regards

  • #5287


    It is  taking 3.5 – 4 hour to decoking the drum and 0.5 hour to make the drum hole. The drum steam purge takes 1.5 h to the main tower with 3 t/h of steam and 45 min to blowndown with 12 t/h. Our water quench flow is 25 m3/h in 2.0 hour, 50 m3/h in  1.0 hour, 100 m3/h in 1.0 hour and 210 m3/h in 2.0 hour. After the soak time is 2.0 hour.  Besides thats we still have hot spot.

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