[Stoves] Gasifying coal?

[Paul S. Anderson]

Dear Crispin and Tom and Stovers,   (following the suggestion from Tom 
Miles, I
am NOT sending these "small gasification" messages to the Gasification
Listserv.)

Yes, I have tried TLUD gasifying of coal.  It is possible to get it to start
making the smoke, but too much smoke for the fibble secondary air 
system that I
had.

Tom reported better results.  Note that coal can have many impurities that end
up like "ash" or simply non-combustible stuff that is held with the fixed
carbon, so Tom's 50% "stove coke" might be only 25% carbon, or even 
less. Would his results indicate a more significant amount of 
carbon-gasification
than what we have come to associate with the relative low amount of
char-gasification in the lower-temperature pyrolytic processes of TLUDs?

Tom's comment about the % of volatiles is important, but also about the MUCH
greater weight.  20% of 1 kg = 200 grams versus 80% of 250 grams = 200 
grams.  Someone can calculate the amounts, but my guess is that by 
VOLUME, the volatiles
in coal approximately equal those of dry biomass.

The real issue is control of the air while maintaining sufficient heat to
sustain the release of the volatiles.  Coal must be hotter.  Does that mean
that the release of gases will therefore be faster than for wood/biomass for
which pyrolysis is in the 400 - 600 deg C range?  Tom, please correct my
statements and help understand this.

John Davies of South Africa is the most experienced person on TLUD 
gasification
of coal, but he only used natural draft.  I believe that he had a tall, 
slender
pile of coal-fuel.  That would allow for high temps in smaller areas yielding
appropriate quantities of gases, and giving longer burn-times (several hours I
believe John told me.).

Considering the abundance of coal, this is a worthy pursuit.  Maybe by ETHOS
time (late January 2008 in Seattle) we could have some meaningful efforts, or
at least have a game plan for looking into this.

Paul
-- 
Paul S. Anderson, Ph.D., Geography professor - Emeritus
Telephone:  USA-309-452-7072 (residence and office)
Internet site:  www.ilstu.edu/~psanders
For my gasifier stoves info, go to:
http://bioenergylists.org/contributors#Paul_Anderson


Quoting Thomas Reed <tombreed at comcast.net>:

> Dear Crispin and All:
>
> In 1998 Robb Walt of CPC asked me the same question:  Can the WoodGas
> stove gasify coal.  Since coal is only 20% volatile while wood is 80%, I
> didn't think so, but having discovered that my opinions are often wrong,
> I got a few chunks of Western Coal from Coors.  (There are long supply
> trains here in Golden, and sometimes pieces fall off - or are helped
> off.  It takes a LOT of coal to make beer.)
>
> I crushed the coal and pea sized it, put it in the stove, ignited it
> with chips/sawdust pellets/coal.  (Coal is hard to ignite) and was
> delighted to find that it burned longer even than wood pellets, being so
> dense.  It yielded about 50% of  "stove coke".   Experiment trumps
> opinion again!  (Some of my best inventions have come from ignoring my
> instincts.)
> ------------------------------------------------------------------------
>
> The charcoal from our woodgas stove can be a useful byproduct.  Any
> suggestions for the "stovecoke"?
>
> Yours truly,
>
> Tom Reed
>
> ------------------------------------------------------------------------
>
> Crispin Pemberton-Pigott wrote:
>> Dear Paul
>>
>> Have you tried gasifying coal with a fan stove??
>>
>> Just wondering what the options are.
>>
>> Regards
>> Crispin in Vancouver
>>
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