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Stuck Bottom Heads

Home Forums Coking Operations Cutting, Drilling, Unheading Unheading Stuck Bottom Heads

This topic contains 7 replies, has 3 voices, and was last updated by  Richard Perk 15 years, 1 month ago.

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  • #4333

    Anonymous

    Sometimes when we drop the bottom head, the Coke will come down as a cylinder and is very solid. The bottom head neither goes back up or pulls out. We aim fire monitors on the cylinder until it finally breaks loose, usually resulting in a blowout on the deck. Does anyone have a better way to break up this cylinder or to prevent it from occurring.
    Thanks
    Frank Lukachinsky
    Delayed Coking Dept
    Team 1 925 229-6106

  • #7765

    Richard Perk
    Participant

    We’ve never had this problem, as far as not being able to move the head after the “hockey puck” falls. We seldom encounter a “hockey puck” but have heard in places were they are more frequent using 1″ stock bar welded to the Drum ID to catch said “hockey puck” and keep it from falling.

  • #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.

  • #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.

  • #7761

    Anonymous

    We have found that three factors most affect the formation of coke on the bottom head:
    – feed composition
    – coking conditions
    – feed distributor design.

    Use of a swingback bottom head or slide valve are the expensive solutions.

  • #7744

    Anonymous

    we have installed a I-R hoist with remote controls to help assist moving the carts, we have also had to call out hydroblasters to cut the plug with high pressure water

  • #7743

    Anonymous

    We have had similar experiences in the past. Determining suspect feeds and weeding them out may not be the cheapest either. We ended up welding low pitch clips to the ID of the cone 2-3″ in length approximately 18″ up from the bottom head flange face. No science to the spacing, the clips serve as a stop mechanism by not allowing coke to slide down the cone wall.

  • #7677

    Anonymous

    After unheading, and breaking up the first ‘hockey puck’, what’s the largest puck you’ve ever seen plunge down the chute, and about how high up in the coker did it free fall from? We’re trying to determine impact energy on the chute in an upset scenario.

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