[Terrapreta] Char made made under pressurized conditions?

[Sean K. Barry]

Hi Jeff, Greg,

I've heard of both a nitrogen flush Nitrogen-N2 and a CO2 used to cool charcoal after it has been produced.  Jeff is right that allowing air containing oxygen to come into contact with hot charcoal will just continue the combustion.  Nitrogen-N2 is a good purg gas because it is relatively cheap and has no oxygen whatsoever (combustion cannot occur).  It N2 is passed through a charcoal bed and cooled , then it will readily remove the heat form the charcoal.

Someone else mentioned another problem with charcoal in containers once.  I think it was a guy from Eprida and Adrianna Downey from Best also confirmed this;  a sealed container of fresh (but cool) charcoal needs to be dumped slowly or aired out first before storing longer.  This is because some of the volatile matter that condenses onto the charcoal as it cools is highly combustible and can even spontaneously ignite in open air.  It's like rags with linseed oil on them in open air in a trash can.

I think I will try to use Nitrogen-N2 in my reactor.  Using cooling with a non-oxidant purge gas can speed up the process of making charcoal by moving charcoal out of the reactor faster.  Dr. Antal's reactor and most kilns/retorts are batch type pyrolysis reactors.  Continuous feed/removal of charcoal systems would likely need to cool charcoal before it is removed from the reactor or immediately thereafter.

Regards,

SKB
  ----- Original Message ----- 
  From: Jeff Davis<mailto:jeff0124 at velocity.net> 
  To: Terra Preta<mailto:terrapreta at bioenergylists.org> 
  Sent: Friday, March 28, 2008 10:38 PM
  Subject: Re: [Terrapreta] Char made made under pressurized conditions?


  Hi Greg,

  I just happen to have that book with me. They explain the four stages of
  charcoal production, the third being the "exothermic period" and that is
  about 400 C. The fourth stage called the "cooling period" comes next but
  they do not state any temperture range. Maybe the cooling period is 400 C
  to safe handling temperature. I honestly do not know.

  I was just wondering if there could be somekind of opportunity for us at
  this stage of charcoal production. Maybe nothing to do with
  nitrogen/ammonia etc but something else.



  Kindest regards,


  Jeff



  > Hmmm........
  >
  > Correct me if I'm wrong, but is it not true that char can still be quite
  > warm, and not burn when O2 comes in contact with it?
  >
  > It is with that in mind that I asked what I did in my previous post -
  > after
  > all, you didn't exactly say at what temp the char was cooling from did
  > you?
  >
  > No offense,
  > Greg H.


  -- 
  Jeff Davis

  Some where 20 miles south of Lake Erie, USA

  _______________________________________________
  Terrapreta mailing list
  Terrapreta at bioenergylists.org<mailto:Terrapreta at bioenergylists.org>
  http://tech.groups.yahoo.com/group/biochar/<http://tech.groups.yahoo.com/group/biochar/>
  http://terrapreta.bioenergylists.org<http://terrapreta.bioenergylists.org/>
  http://info.bioenergylists.org<http://info.bioenergylists.org/>

-------------- next part --------------
An HTML attachment was scrubbed...
URL: /attachments/20080329/2e190542/attachment.html