[Gasification] Gasifier Fuel Size-qualifying gasifier

Mon Dec 17 14:53:02 EST 2007

The disucssion regarding fuel sizing only applies to fised bed, 
downdraft gasfiers as I can tell and has been told and retold 
repeatedly. The Texaco/GE coal gasfier is a downdraft and uses a very 
fine coal slurry. Gasification of rice hulls is certainly a fine fuel 
size. It is interesting that any fuel introduced to the system breaks 
down into fine particles when heated and that the residence time has a 
significant influence on the reaction of the fine particles.

Leland T. "Tom" Taylor
President
Thermogenics Inc.
7100-F 2nd St. NW
Albuquerque, New Mexico USA 87107
Phone: 505-463-8422, fax: 505-268-9206 Web:thermogenics.com
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-----Original Message-----
From: Thomas Reed <tombreed at comcast.net>
To: Discussion of biomass pyrolysis and gasification 
<gasification at listserv.repp.org>; STOVES at LISTSERV.REPP.ORG 
<STOVES at LISTSERV.REPP.ORG>; Shivayam Ellis 
<shivayam.ellis at comcast.net>; Tyler Premo <synthesizeracing at gmail.com>; 
Agua Das <aguadas at onebox.com>; Jim Fournier <jim at planetwork.net>
Sent: Mon, 17 Dec 2007 7:55 am
Subject: [Gasification] Gasifier Fuel Size

Dear Greg and All:

I remember learning in spades the lesson you are teaching concerning
gasifier fuel sizing.  In 1978 the folks at UC Davis had a 50 kW WWII
gasifier, ran it and got excellent results.  On the basis of these
results they obtained a contract to make a 500 kW gasifier for the
California State Printing Office using wood chips.  They built it and 
it
was the greatest tar producer the world ever saw!

A year later I was talking to a South American gasifier maker ( I hope
someone can improve on these facts but the principle is right here...). 

He had built and was regularly operating a 500 kW gasifier.  I was
puzzled - how come for him, not for them.  He told me they were using
fist sized wood chunks of wood hacked off with a machete!

Arguably the WWII gasifier is the best yet made with a record of a
million used by the civilians faced with starvation.  (There is some
evidence that Nils Bohr was on the committee that designed the on used
in Denmark.)  They used match box sized hard wood (Beech?) blocks.
Obviously the lateral depth of penetration of the air blast into the
fuel is VERY important in having air around each particle to burn the
emerging tars as it pyrolyzes.

Thanks for the musings Greg...

Yours truly,

TOM REED            BEF

ÐÏà¡±á

Greg Manning wrote:
> Hi everyone,
>
>  Some of you know me, some don't, for those that don't, the locals 
call me
> "Mr. Fusion" (from "back to the future", LOL). Anyhow, it's been one 
heck of
> a year, I haven't really had time to even be home, let alone work on
> gasification, Ironically the heavy construction outfit I work for, 
ended up
> doing five crude oil pipeline sites this year, and I've spent the 
last 5
> months, traveling from site to site as needed.
>
> Of course, this left me in hotel rooms most evenings, with nothing to 
do
> except watch TV (mostly 3 or 4 channels, one hotel had cable) 
remember, this
> is the "great white north up here" and satellite is our only option 
for
> decent TV, anyhow, I did much reading and thinking on the gasification
> process.....
>
> And since it is the season to give.... I'll just ramble, you guys can 
sort
> it out :)
>
> I've observed the following  with block or chunk burns, open air, or
> gasifier,
>
> 1> The thermal mass (chunk that is not burning under the surface of 
the
> burning area), does in fact negate the chunk's burn area from reaching
> "thermal reduction temperatures" capable of PAH and tar reduction.
>
> 2> Item 1 would then dictate that all mass intensive sizing of fuel, 
would
> then follow this same pattern until such point that the thermal mass 
has
> reached "thermal equilibrium" with respect to chunk size vs. 
temperature (at
> some point the entire chunk becomes a glowing "coal") this I assume 
would be
> that equal area, and in fact at this point, and only this point, can 
the
> balance of this chunk of fuel become "thermally reduced into 
elemental gases
> and compounds".
>
> 3) With items 1 & 2 being what they are,  there is a direct 
correlation to
> not only tuyere to throat to reduction size, BUT also  fuel chunk 
size, to
> tuyere, to throat, to reduction size.....
>
> 4) With all the above said, the bigger the bits of fuel are, the 
larger the
> gasifier needs to be.... (and here you thought I was onto something :)
>
> With all the above, I will say this, Fuel size is a CRITICAL portion 
of
> proper gasifier operation, and little to no tars, PAH, NOx, etc.
>
> wood chips anyone ?
>
>  Seasons Greetings !
>
> ho ho ho !
>
>  Greg Manning,
>
> Brandon, Manitoba, Canada
>
> currently,  Minus -20, light snow, 3 feet of base, now if I could 
only find
> a hill when I need one. :)
>
>
>
>
>
>
>
>
>
>
>
>
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