[Gasification] [Digestion] composition of pyrolysis gas

Jeff Davis jeff0124 at velocity.net
Fri Jan 28 20:10:48 CST 2011

Dear Dr. Karve,

I did not see a percent composition in my book.


Industrial charcoal making

"Thus it is difficult to give exact figures for gas composition and
heating value. A typical retort gas could have the following composition
by volume:- methane 17%, hydrogen 2%, carbon monoxide 23%, carbon
dioxide 38%, oxygen 2% and nitrogen 18%. Offgas from rinsing gas retorts
could be diluted more than its own volume with inert rinsing gas.

The calorific value varies widely. Undiluted retort gas has a calorific
value of about 11 MJ/m³ but would be less than half this when diluted
with inert rinsing gas being approximately equal to producer gas. The
gas will burn easily but the heat output is limited. For every tonne of
charcoal produced about 0.25 tonnes of non-condensable gas is produced
having a heat content about 10% of that of the charcoal produced."



"Approximately from one thousand kilograms of dry wood the following
heat quantities are available in megajoules (MJ) in the final products.

Charcoal 9500 MJ

wood Gas 1500 MJ

Condensibles including Tar 8000 MJ"


And of course root:


Best regards,


On Tue, 2011-01-25 at 08:33 +0800, Anand Karve wrote:
> Does your book contain the percentage composition of the fraction that
> remains gaseous at room temperature (carbon dioxide, carbon monoxide,
> hydrogen, methane and water vapour)? It is the gaseous fraction that
> would serve as fuel analogous to biogas. The rest of the chemicals are
> most probably components of the tar, which condenses at room
> temperature. Yours A.D.Karve 



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