[Terrapreta] Char made made under pressurized conditions?

[Sean K. Barry]

Hi Jeff,

You should read the work of Dr. Michael J. Antal from the University of Hawaii.  Some of his papers are listed on the 'terrapreta' site.  He has built several 10 ton per day pressurized pyrolysis reactors and the UofH and him license them.  He claims charcoal yields as high as 35-40% (dry weight charcoal/weight of biomass feedstock) and 93% fixed Carbon (fC) in the charcoal.  He is very knowledgeable about the bio-chemistry of the pyrolysis reaction.  He demonstrates that using pressure allows one to produce a higher yield of charcoal with most any biomass (wet or dry) and the reaction under pressure is also much faster; ~30 minutes per 1 ton? charge as opposed to 24 hrs per charge for standard air pressure operated reactors/kilns.

The retort is a vessel that is lowered into a pressurized capsule.  The reactor operates at ~150psi , I think, and is air-blown.  The biomass is heated by an electric coil in the bottom of the retort, while air (at pressure) is pulled through the biomass from the top of to the bottom of the retort.  This is all done under pressure, until the reaction is self-sustaining (exothermic).  Then the air flow (fuel/oxygen mixture) is maintained to reduce gas production and increase charcoal production.  That smaller amount of producer gas which is emitted is burned in a catalytic converter.

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 6:34 PM
  Subject: Re: [Terrapreta] Char made made under pressurized conditions?


  Dear Greg and All,

  Some of the better charcoal made for the portable gas producer allowed the
  charcoal to cool in the carbonizing apparatus itself. The charcoal would
  absorb some of it's own off gasses thus resulting in a higher carbon
  content charcoal. Although I doubt that these retorts were under pressure
  I bet pressure would be an aid.

  Greg, do you think if we injected nitrogen in the retort during the
  cooling period that the charcoal would absorb the nitrogen for better soil
  amendment?



  Kindest regards,

  Jeff




  Greg wrote:
  > While thinking of the modifications, I remembered that someone on the
  > list, mentioned trying to use a water heater, to make a retort, and going
  > over what might be needed to modify the water heater for such use, I
  > remembered that water heaters have pressure release valves, and the
  > question occurred to me, " What would be the result of producing char,
  > under pressurized conditions? "
  >
  > The more I pondered it, the more the idea intrigued me.
  >
  > Does anyone know what would be the result of such char production?
  >
  > Under low pressurized conditions ( say 15-25 psi )?
  > Under mid range pressurized conditions ( 25-50 psi )?
  > Under high pressurized conditions ( 50+ psi )?
  >
  >
  > One thought, is that distillates would ( at increasing pressure ), have
  > carbon chains of increasing size.
  >
  > Does anyone else have any idea?
  >
  >
  > 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/20080329/4d5b3475/attachment.html