[Gasification] Gasification Digest, Vol 2, Issue 22

[Geoff Thomas IMAP]

Hi Ken, if superheated steam is a replacement for a significant  
portion of the incoming gas then the proportion of outgoing nitrogen  
should be less, and significant oxygen provided by the incoming H20.
I guess the trick is to split the water before it or as it hits the  
glowing carbon, so the carbon gets enough oxygen to continue "burning".
I wonder how hot the steam would need to be?
Geoff.


On 19/10/2010, at 6:14 PM, gasification- 
request at lists.bioenergylists.org wrote:

> Andy,
>
> I'd also like to start a discussion about direct contact of the wood  
> chips
> with the exhaust gas.  A pre-processing reactor that cooks the chips a
> little batch at a time then dumps them into the main gasifier  
> reactor, via
> auger feed. As you say a "just in time" pipeline flow of pre-cooked,  
> pre-
> heated reactants.  Water can be added if necessary as steam.
>
> Clearly the wood will become torrified, and the exhaust gas stream  
> will
> drive off and purge the wood fuel of moisture and volatiles, whilst  
> raising
> the temperature of the fuel considerably.  There will also be an  
> increase in
> fuel energy density.
>
> If diesel exhaust was used (I'm thinking of a dual fuel Lister being  
> started
> up on diesel to raise process heat and provide mechanical and  
> electrical
> power for starting up gasifier), this will contain between 8% and  
> 17% unused
> oxygen, and around 80% nitrogen.  Would the O2 be of sufficient  
> quantity to
> cause partial oxidation of the fuel and possibly more heat?
>
> If the exhaust is from a woodgas engine - it will again be around 80%
> nitrogen, plus CO2 and CO.   If this relatively inert hot gas is  
> used to
> purge the woodfuel of all moisture and volatiles - is the resultant  
> off-gas
> ever going to have sufficient combustible constituents that it could  
> be
> ignited in any sort of air fed burner - or is the nitrogen loading  
> just too
> high?
>
>
> Thoughts appreciated,
>
>
>
> Ken