Re: law of mass action

[Reedtb2@cs.com]

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.