[Terrapreta] Let's talk retort materials for a little bit

[Greg and April]

While clay may work for outer shell material, it has some serious problems, not the least of which is the fact that it has a fairly high thermal mass, that has to be over come and that leads to efficiency problems since the clay will act as a heat sink, until up to temperature.

Different types of clay are reasonably available, but the proper types can be hard to get.    Fire clay would be the best choice as it has good thermal stability, but is actually fairly rare unless you have a coal mine handy - and even then there is no guarantee that you will have the proper type of clay available.

Use the improper type of clay, or clay with a high level of impurities, and it can result in failure of the shell right in the middle of a burn.

Greg H.

  ----- Original Message ----- 
  From: David Yarrow 
  To: terrapreta at bioenergylists.org 
  Sent: Wednesday, May 14, 2008 14:05
  Subject: Re: [Terrapreta] Let's talk retort materials for a little bit


  clay?  abundant, cheap, natural, widely available, almost free, low tech, easy to dispose of.

  of course, a basic question:
  are you making charcoal just to make charcoal?
  or are you trying to generate biofuel?
  or are you just trying to co-generate space heating?

  different designs for different applications.

  for a green & peaceful planet,
  David Yarrow
  44 Gilligan Rd, E Greenbush, NY 12061
  www.championtrees.org
  www.OnondagaLakePeaceFestival.org
  www.farmandfood.org
  www.SeaAgri.com
    ----- Original Message ----- 
    From: Greg and April 
    To: Terra Preta 
    Sent: Wednesday, May 14, 2008 3:18 PM
    Subject: [Terrapreta] Let's talk retort materials for a little bit


    What kind of materials make a good retort?

    Titanium?
    Carbon Steel?
    Stainless Steel?

    What?

    Greg H.



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