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Thread: Wood Chip Bin Bridging

  1. #1
    dhatt Guest

    wood chip bin bridging

    We use wood chips of varying size.
    Bins 12'x12 ft with 60 deg bottom
    bottom opening is 2ftx 4 ft .
    we tried to use auger at the bottom about 3 ft from the bottom opening.
    Severe bridging is seen about 18 inch above the auger .
    Any help will be appreciated

  2. Bridging of wood chips

    The wood chips will interlock and form a strong mass under the pressures of the overlaying material. It may be practical to utilise flow inserts to avoid this consolidation, but there is not enough information in the query to put forward a proposal. As it is unlikely that there will be close control over the size, shape and condition of the chips, it would be difficult to produce a guaranteed solution for the current hopper design, but it is likely that a relatively simple over-pressure relief modification would give some improvement and be worth undertaking. If you care to contact lyn@ajax.co.uk, we could discuss the situation.

  3. #3
    Join Date
    Mar 03
    Posts
    1,641
    Wood chips can be a real problem extracting from a bin.

    To be honest, my opinion is that with a rectangular bin of the size you give you really need to ditch the present converging section and use a mechanical extractor to extract from as much of the plan area of the bin as possible. Do a search for people in the woodchip business and the equipment they use. There's a lot of experience in Scandinavian countries.

  4. #4
    Marcel Van Giel Guest

    Re: wood chip bin bridging

    Originally posted by dhatt
    We use wood chips of varying size.
    Bins 12'x12 ft with 60 deg bottom
    bottom opening is 2ftx 4 ft .
    we tried to use auger at the bottom about 3 ft from the bottom opening.
    Severe bridging is seen about 18 inch above the auger .
    Any help will be appreciated

    When storing an interlocking material such as wood chips in a silo, you have to prevent compacting and reduce the pressure on the bottom layer.
    This can be done by adding wedge like plates to the inner wall.
    A flat bottom with extractor will be required as the product will bridge in a cone, sometimes even in the cylinder.
    A number of companies specilised in the storage and handling of wood chips for the paper industry and fiber board.
    Try: SHW, Saxlund, Vecoplan, Koch, Sunds, Andritz, FMW and I'm sure this list is not complete.

  5. #5

    Bridge Breaker Flow Aid

    Oftentimes, bridging can be defeated by the use of a flow aid that applies its energy directly to the material rather than the bin. With conventional flow aids such as externally mounted vibrators, the bin walls tend to absorb most of the energy from the vibrator. What little energy that does make it through to the material can sometimes compound the flow problem by making the material compact.

    Conversely a flow aid consisting of an expanded metal screen that is installed inside and parallel to the bin wall and connected to an air shaker installed outside of the bin via flexible isolation mounts can effectively shear/under cut the material's bond to the bin wall and result in gravity flow.

    Several of these devices can be installed in series to promote flow over a wide area.

    More information would be required to determine if this type of flow aid would be a suitable solution to your problem.

    See attached casehostory and visit www.thayerscale.com and click on the "material flow aids" tab for more information.
    Attached Files Attached Files

  6. #6
    Join Date
    Mar 03
    Posts
    1,641
    Bridge Breaker Flow Aid
    Has such a unit been used successfully on wood chips?

  7. #7

    Bridge Breaker Flow Aid

    The file attachment from my previous reply is a case history of a wood chip bin with an auger discharge. Although the Bridge Breaker Flow Aid has solved this, and other similar wood chip bin flow problems, we would need to know more about your material and your bin details to know if this flow aid would be suitable for you.

    If you email me at amcintosh@thayerscale.com I will send you an application data sheet that you can fill out. Once we receive your completed data sheet we will either advise that, based on your information, this flow aid would not be suitable, or send you a cost proposal along with an installation list of wood chip applications if we believe the flow aid will work for you.

    Best regards,

    Allen McIntosh
    amcintosh@thayerscale.com

  8. #8
    Join Date
    Mar 03
    Posts
    1,641

    Re: Bridge Breaker Flow Aid

    Originally posted by Allen K. McIntosh
    The file attachment from my previous reply is a case history of a wood chip bin with an auger discharge.
    Sorry having problem with pdf's attached in this forum.

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