[Gasification] Gasifier Fuel Size

[Benjamin Domingo Bof]

Dear Doctor Thomas B. Reed; of course,

was the greatest tar producer the world ever saw!

This is not a bad question . For me we must act as in yudó. Using adversary inertia.
If we consider to distill in high teperature obtaining coal, tar and gas probably gasifier yield is much better.Chunkettes are very good using gravity law.Velocity of charcoal making in wood surface is 1 1/2 inch an hour of heat trasmission. Then wood offer an support of material being gasified. Outer part are giving gasses and 
part is cold waiting to increase temperature. I remember many years ago an paper published by USFS suggesting to use conveyor screw to carbonizes saw dust. Horizontally all is very simple. With an cricket we obtain pulse movement to rotate screw. As Doctor Reed define "Rosetta stone" for energys "Gravity law" is a choice . Vertical draught for firewood and horizontal gassers for saw dust and others fines from agri wastes.
Regards, Benjamin





Thomas Reed <tombreed at comcast.net> escribió: 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

ÐÏࡱá



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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