Refining Community Logo

coker squirrel

Forum Replies Created

Viewing 15 posts - 1 through 15 (of 35 total)
  • Author
    Posts
  • in reply to: Drum overheads #6866

    coker squirrel
    Participant

    We are experimenting with running the quench oil on temperature control.  We are looking for an optimum point so that we can keep the vapor line “wet” enough to prevent coking and at the same time hold down the recycle ratio and keep the Fractionator Flash Zone more consistent through slump (warm-up and drum switches).  At what temperature do we need to keep the coke drum overhead line cooled down to prevent coking?

  • in reply to: abc #7625

    coker squirrel
    Participant

    I am a little concerned about injecting slurry at the top of the drum.  This may be hard on the metallurgy above the coke bed if injected at the beginning of a quench cycle while the metal is still hot.

  • in reply to: banana effect #7637

    coker squirrel
    Participant

    I have heard of a new “floating skirt” disign that allows for a little displacement.  I don’t know much about it.  Maybe someone could explain this new technology.

  • in reply to: Delta Valve as alternate Drain #7639

    coker squirrel
    Participant

    We have now been operating Delta Valves for nearly a year.  We have experienced what I call a “false bottom.”  The false bottom is the solidified layer of coke in between the Delta Valve gate and the feed line entry point.  Most of the time as we open the Delta Valve, an adequate amount of water does come out and we can drain that way, but at times we can open the Delta Valve full open and not get a very good drain for a few minutes then the “false bottom” falls out.  Sometimes this leads to a blowout.  Are there others experiencing simular events?

  • in reply to: Coke Drums Vapor Line – Gate valve at Frcactionator #7650

    coker squirrel
    Participant

    You might consider a Delta Valve.  I had heard that the Delta Valve was originally proposed for this service (isolation of the vapor line at the Fractionator).  While evaluating whether or not to use the Delta Valve for this service, someone came up with the idea to use the Delta Valve for the Bottom of the Coke Drum.

  • in reply to: Delta Valve Steam Purge #7651

    coker squirrel
    Participant

    We are doing the same, holding a straight 80 psig purge.  You are right, the pressure tap should have been ahead of the switch valve.

  • in reply to: feed stock changes #7727

    coker squirrel
    Participant

    Thanks for the explaination. I didn’t know exactly how the clarified oil worked but your explaination makes sense.

  • in reply to: Stuck Bottom Heads #7763

    coker squirrel
    Participant

    Something else we used to do in this situation. We would also use fire monitors to try to break it up but we sometimes also had to use the air hoists to pull a cable through the coke core to “cut” the coke. Hope this helps.

  • in reply to: Stuck Bottom Heads #7764

    coker squirrel
    Participant

    You must have the manual type of bottom unheading where the bottom head comes down on a head cart and then the head cart along with the bottom head is moved out from under the drum. This type of unheading was the first type that we had. We have since upgraded twice. We moved to the Hahn & Clay swing away unheading and then we moved to the Delta Valve. Under the first type of unheading device, sometimes we would experience the solid “core” at the bottom of the drum to come down with the head. This usually occurred when we didn’t get a good enough drain and due to the water head pressure on top, it would push the core down on the head. When this occurred, we would use air hoists from the companion drum to help pull the cart from under the drum. We would apply the extraction force on the head so that we wouldn’t pull the head cart out from under the head. The Hahn & Clay swing away elimitated this problem but the best alternative is the Delta Valve.

  • in reply to: Back Pressure for Drum Warm-up #7771

    coker squirrel
    Participant

    Have you also tried using this backpressure valve to help suppress the foam front? I am thinking that this could help not only for drum warm-up but also as means of slowly letting down the drum pressure to prevent the drum from foaming immediately after switching feed from the drum and the introduction of quench steam. Do you have the backpressure valve set up to control from the DCS Control Room?

  • in reply to: Back Pressure for Drum Warm-up #7774

    coker squirrel
    Participant

    Do you have a vender contact for the type of backpressure butterfly valve that you use? What has your Drum warm-up time changed from and to when you use the butterfly valve? What percentage do you close down on the butterfly?

  • in reply to: Plugged Heater Tube #7795

    coker squirrel
    Participant

    I did look up hydrokinetics on the net. There is a company nearby that does this process. We are probably near completion with the hydroblasting by now but this hydrokinetic process may be a good option to look at the next time. Thanks for the advise!

  • in reply to: low flow recovery #7802

    coker squirrel
    Participant

    Skins <1300°F and outlet <880°F is the general rule of thumb I go by.

  • in reply to: feed stock changes #7803

    coker squirrel
    Participant

    Clarified Oil is Cat Cracker bottoms. Shot coke is low in asphaltenes. Clarified Oil will help with additional asphaltenes as a bonding agent.

  • in reply to: feed stock changes #7806

    coker squirrel
    Participant

    Some crudes tend to foam more than others. If the foaming is happening after switch, be careful not to inject too much quench steam. If the coke is shot, you may try decreasing heater outlet temperatures. Quench water tends to channel through shot coke. You may also want to track your crude slates to develop a history of how certain crudes react. You can also try adding a little clarified oil to settle things down.

Viewing 15 posts - 1 through 15 (of 35 total)
Refining Community