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Sludge recycled to DCU

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This topic contains 8 replies, has 4 voices, and was last updated by  chiou 7 months, 3 weeks ago.

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  • #24793

    chiou
    Participant

    Dear all

    We have several question about recycling waste product from petroleum refineries (such as oily sludges produced during refining processes). Do you use a delayed coker unit to recycle the refiner sludges? If you do so, do you feed the sludges to the coke drum during the coking phase of the cycle or during the quench phase of the cycle? What are the pretreatment procedures for the sludges before it is fed to the coke drum? What are the limitations(quality, quantity, temperature, water content ,etc.) of
    the sludges fed to coke drum during coking phase or quench phase? We would be very appreciated for getting your reponse.

  • #24843

    Evan Hyde
    Keymaster

    Yes, there are plants that feed sludge during coking and quenching. The pretreatment requirements vary by the type of sludge being processed. The original systems were called iMOSC for water sludge injection. Most sites will mill the sludge to have a more uniform particle size, typically <100 micron, and are kept in suspension in at least 50% water. Personally, I like 75%+ water to prevent equipment wear. Injection quantities are typically limited by drum temperature to ensure smelly molecules are destroyed or recovered. Again, temperature numbers vary but >650F is a good start.

  • #24859

    chiou
    Participant

    Dear sir
    I am very appreciated for your reply. Our refinery prefer to feed the sludge to DCU coke drum during quench phase of the cycle. Is the temperature limitation >650F for feeding sludge during quench phase? What is iMOSC system? Do you have iMOSC system (know-how,equipment) vendor information so that we can contact.

  • #24860

    Evan Hyde
    Keymaster

    You can learn more from these patents:
    1975 Patent 3917564 Disposal of Industrial and Sanitary Wastes, Mobil Oil
    1985 Patent 4666585 Disposal of Petroleum Sludge, Atlantic Richfield
    1988 Patent 4968407 Sludge Dewatering and Destruction within a Delayed Coking Process, Foster Wheeler
    1989 Patent 5009767 Disposal of Industrial and Sanitary Wastes, Mobil Oil
    RE Temperature, yes, that’s during the sludge injection initially in the quench phase after steamout.
    RE vendors, all the DCU licensors (AFW, BHTS, Lummus) can design/build the system for you. Veolia and a few other companies can provide the sludge pre-treatment.

  • #24861

    Evan Hyde
    Keymaster

    You can learn more from these patents:
    1975 Patent 3917564 Disposal of Industrial and Sanitary Wastes, Mobil Oil
    1985 Patent 4666585 Disposal of Petroleum Sludge, Atlantic Richfield
    1988 Patent 4968407 Sludge Dewatering and Destruction within a Delayed Coking Process, Foster Wheeler
    1989 Patent 5009767 Disposal of Industrial and Sanitary Wastes, Mobil Oil
    RE Temperature, yes, that’s during the sludge injection initially in the quench phase after steamout.
    RE vendors, all the DCU licensors (AFW, BHTS, Lummus) can design/build the system for you. Veolia and a few other companies can provide the sludge pre-treatment.

  • #24880

    Mike Kimbrell
    Participant

    As Evan stated, many Delayed Cokers inject sludge during the water quench phase. Preparing the sludge is important. Size reduction to very small size and controlling the total solids loading in the water slurry and minimizing the free oil in the water slurry are important to a successful operation. Stopping the sludge injection and replacing it with quench water at a drum overhead temperature limit is another requirement for a successful operation. The sludge should convert on the hot coke, which is why monitoring the drum overhead temperature is important. Otherwise, the sludge just coats the coke in the drum and does not convert. This results in extremely strong odors that could result in exposure to hydrocarbons by the decoking crew or anywhere the coke is moved.

    Sludge coking has been practiced and is practiced at some units. The sludge is slurried with oil rather than water and injected into the coke drum. Several patents have been issued that have the sludge injected into the feed line or into the top of the coke drum. Any sludge injection during the coking phase will reduce the feed rate to the Coker, or will lower the drum outlet temperature which will increase the coke yield and likely increase the VM of the coke produced. The advantage of the coking phase injection is the sludge is converted and additional odors from the coke once it is removed from the drum are minimized.

    I believe that sludge injection during the water phase is the most common method of sludge coking. It utilizes the stored energy in the coke bed to convert sludge into additional products. The rate of injection of the water slurry has to be managed similar to what the little water rate would be to prevent damage to the coke drum from excessive stresses caused by the initial water cooling rate being too high. Solids that are too large or solids loading in the water slurry that is too high have been associated with incomplete quenching of the coke bed due to channeling of the quench water through the coke bed.

    Sludge coking during the water quench phase can be accomplished safely; however, there are lots of parameters that have to be monitored and complied with for that to be true. Within the USA, the environmental regulators have a belief that sludge coking during the water quench phase increase emissions during drum venting. The data on emissions on drum venting show a very large range and sludge coking does not seem to correlate with emissions; however, the data are extremely limited.

  • #24883

    chiou
    Participant

    Thanks a lot for Mike’s reply. It is very worthy to us. We are very concerned about the possible strong odors that could result in exposure to hydrocarbons by the decoking crew or anywhere the coke is moved. So I wonder the drum overhead temperature limit for Stopping the sludge injection and replacing it with quench water.

  • #24885

    gary m pitman
    Participant

    Hello Chiou,
    Patrick Hagen at Clean Harbors designs and builds sludge injection system and he is a wealth of information.
    Here is his contact information.

    Contact Name
    Patrick Hagan
    Phone
    +1 707.747.6699 Work
    Phone
    661-201-0152 Mobile
    Email
    hagan.pat@cleanharbors.com Work
    Work Address
    4101 Industrial Way Benicia, CA 94510 United States

  • #24890

    chiou
    Participant

    Thanks for Gary’s information!

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