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-
[email protected] 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
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