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Thread: Wood Torrefication

  1. #1

    Wood Torrefication

    Has anyone torrefied lumber (essentially heat stabilization)? TIA.

  2. #2
    There is considerable discussion of wood sterilization on forestry forum.

  3. #3
    Join Date
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    I'd be interested in learning more about this too. Torrefaction, insofar as we're interested in it here, would achieve sterilization but that's not the primary point (at least for me)--it results in different characteristics for the wood (different physical characteristics, greatly increased rot resistance, ?)

    I did a little bit of searching a while back, but didn't find much on how exactly it's done, on what, and what the properties achieved are.

  4. #4
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    Check wikipedia etc. for Torrefaction - the usual disclaimers about taking wikipedia as gospel apply. Here is a portion:

    Torrefaction is a thermochemical treatment of biomass at 200 to 320 C (392 to 608F). It is carried out under atmospheric pressure and in the absence of oxygen, i.e. with no air. During the torrefaction process, the water contained in the biomass as well as superfluous volatiles are released, and the biopolymers (cellulose, hemicellulose and lignin) partly decompose, giving off various types of volatiles.[3] The final product is the remaining solid, dry, blackened material[4] that is referred to as torrefied biomass or bio-coal.

    During the process, the biomass typically loses 20% of its mass (bone dry basis) and 10% of its heating value, with no appreciable change in volume. This energy (the volatiles) can be used as a heating fuel for the torrefaction process. After the biomass is torrefied it can be densified, usually into briquettes or pellets using conventional densification equipment, to increase its mass and energy density and to improve its hydrophobic properties. The final product may repel water and thus can be stored in moist air or rain without appreciable change in moisture content or heating value, unlike the original biomass from which it is made.

    The "absence of oxygen" part makes it not so simple. Here is a part that may be relevant to this audience:
    Miscellaneous uses:

    C. F. Martin & Co. uses torrefaction to obtain more dimensionally stable product than traditional kiln-drying or air-drying provides, resulting in guitar parts that they claim are similar to older pieces of wood. They state that, "We believe this allows us to approximate the tone of a vintage guitar." [7]

  5. #5
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    Yep, that's a good overview Curt but what would be interesting to me, if it exists and is public, is a database that relates type of wood, treatment parameters, and measurements of the outcome. E.g.: Hard maple heated at 300C in nitrogen for 3h has a Janka hardness of X and a Young's mod of Y...

    Basically, the things one would like to know if either interested in making or interested in using torrefied wood.

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