[Terrapreta] Fwd: Cellulosic biomass into Ethanol conversion.

[David Yarrow]

yes, sean nails the technical description pretty in two nicely crafted paragraphs.

if larry is already condensing wood vinegar, why not shunt the gases to the other end of the system and burn them to fire up the retort?  move his system design in the direction of self-sustaining.

David Yarrow
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  ----- Original Message ----- 
  From: Larry Williams 
  Sent: Saturday, November 10, 2007 4:27 PM
  Subject: [Terrapreta] Fwd: Cellulosic biomass into Ethanol conversion.

  Rich--------Sean comes through on this post. I have been waiting for an explanation that clarifies what is happening in the retort that I have been using. As mentioned earlier, I have been stalled (not being a researcher) as to what I have been seeing. Specifically, Sean's comments explain or give me a direction to ponder. The quote below covers aspects of both the mound burning technique and the retort technique.


  For example:
  "Pyrolysis is called thermo-chemical reaction because is occurs as a result of high heat.  Biology is killed at pyrolysis temperatures.  When biomass is heated (externally at first) the first thing to occur is that water is driven out of the biomass.  Essentially it is boiled away and escapes as steam.  Then above 150 C or so, the cellulose and lignin begin to decompose, breaking apart the long carbohydrate strings.  This is all in the endothermic stage of the reaction.  This means it requires the input of heat (or oxygen and complete combustion (burning) of some of the biomass feedstock) to continue.  Eventually though, at about 250 C, the reaction becomes exothermic.  This means that there is then enough heat being released by the decomposing molecules that the reaction becomes self-sustaining, without the continuance of added external heat.


  In the exothermic stage of a pyrolysis reaction, hot incomplete combustion gases are being driven out of a charcoal "bed".  The combustion is incomplete because the amount of oxygen is limited.  The heat breaks up the carbohydrate molecules in the charred biomass, rendering some fuel gases; Hydrogen gas-H2, Carbon monoxide-CO, Methane-CH4, Ethane-C2H6, etc.  The fuel gases are incomplete combustion products.  There was not enough oxygen for them to have burned (oxidized).  There are also some complete combustion product gases exiting from a pyrolysis reactor/gasifier; Carbon Dioxide-CO2 and Water vapor-H2O.  CO2 is burned CO.  H2O is burned H2.  Complete combustion (burning) means combining with oxygen and releasing heat."


  I do think that it is important to learn what the smoke can tell us in the pyrolysis process which I will continue (for a while) to vent the retort (less than 3 cu ft capacity) while capturing as much of the wood vinegar as possible. There have been some questions, in my mind, about the heat source (propane) being greater than the energy value of the wood vinegar and the charcoal. There are many more questions to be answered about the products from the condensate-------Larry
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