Re: law of mass action

["Paul S. Anderson" <psanders@ilstu.edu>]

Tom and Mike,

You guys are GREAT resources.  But I need some additional help with
this topic.  My question is mainly to Tom.

So what does this reversability stuff mean to me when I am involved with
a gasification process such as with a modified IDD gasifier (ala Reed -
Larson)?

I want to heed your warnings about the iron rules of
thermodynamics.  But what does this reversability info mean about
making charcoal in an IDD style gasifier?  What should I be trying
to do, or trying NOT to do, especially in terms of heat and fuels and
etc.?  More air, less air, when, where, what type of charcoal is
best and how to get it.

Or what else should I know.....?? (I am not sure even how to ask the
question.)  

Please, guide me along a little more on the very practical side of this
topic.

Paul 

At 10:06 AM 1/25/02 -0500, Reedtb2@cs.com wrote:
> Dear All: 
>
> Mike is quite correct about the irreversability of pyrolysis reactions
> which occur in the 300-500C range.   
>
> However, most of the gasification reactions occur in the 700-1000C range
> and ARE reversible (some quenchable) so that equilibrium predictions are
> often surprisingly close to observed.   
>
> AND I have been pleasantly surprised that while not predictive of
> specific components at lower temperatures, they do predict the magnitude
> of char formation (33%) even at 600 C, the "equilibrium pyrolysis
> temperature" predicted by the thermodynamic calculations of Prof.
> Ray Desrosiers in our 1980 "Survey of Biomass Gasification",
> soon to be RE PUBLISHED by the BEF PRESS. 
>
> (To paraphrase, "Those who don't understand the predictions of
> thermodynamics are doomed to continual frustration trying to break its
> iron rules").   
>
> Look for the book soon, new title, 
>
>     ENCYCLOPEDIA OF BIOMASS THERMAL CONVERSION  
>
> Yours
> truly,                               
> TOM
> REED                      
> BEF PRESS 
>
>
>
>
> In a message dated 1/22/02 12:11:53 PM Mountain Standard Time,
> mantal@hawaii.edu writes: 
>
>
> > As noted in the discussion, the law of mass
> > action pertains to reversible 
> > chemical reactions.  Unfortunately, biomass pyrolysis involves
> > irreversible 
> > reactions.  Try to adjust temperature and pressure a little to
> > recover wood 
> > from charcoal, pyrolysis oils, and gas!  For this reason, the law of
> > mass 
> > action is largely irrelevant to any analysis of charcoal formation. 
> > Regards, Michael Antal.

Paul S. Anderson, Ph.D.,  Fulbright Prof. to Mozambique 8/99 - 7/00

Dept of Geography - Geology (Box 4400), Illinois State University

Normal, IL  61790-4400   Voice:  309-438-7360;  FAX:  309-438-5310

E-mail: psanders@ilstu.edu - Internet items:
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