[Stoves] The Art of Using Grass Bundles in TLUD Stoves

[Paul Anderson]

Dear Julien and others,

First, Crispin is so quick that I did not have a chance to say what 
would have been precisely what he wrote.  Spot on.

Second, the experiment has provided the "bookend" experience for slowing 
the pyrolysis.   The "bookend" of experience for doing the pyrolysis 
much faster has also been done and reported here recently.   Now Julien 
and the collective "we" have a better understanding of control of the 
process.

So, repeat with the same fuel packed the same way but with controllable 
primary air.   Also good to be able to do a coarse adjustment of the 
secondary air to prevent the gases from being too diluted.  Do not 
expect an hour of gas making.   But if the grass/straw (or small reeds 
as seen in the Wendelbo videos) are properly "managed" in the gasifier, 
you will gradually close in on a solution.    (I did not say THE 
solution, because there could be others, but you (we) only need one that 
works.)

You are in new territory, and at the frontier.   Reed, Wendelbo, 
Anderson, English, Larson, Mukunda, Belonio, Pemberton-Pigott, and 
certainly others have also been at that frontier.   BUT, with the 
possible exception of Wendelbo who used reedy grasses and not your 
straw, the others did their work with different fuels.   Many of us 
"experimented" with grasses and were not successful, and we accepted 
success with different fuels.    But dedication can have its pay-back.   
The classic example is Belonio who was shown an early TLUD and told that 
it could not work with rice husks.   (The presenter should have said 
"has not yet been shown to work with rice husks.)  But Alexis LOVES rice 
husks, and took up the challenge, and succeeded.   And we hope that will 
be your story also.

So, Julien (and others), lead on!!!!!!!   We need you and more people 
like you to push the frontiers of micro-gasification.

I have said before:  "I believe that perhaps 20% of what is to be 
learned about TLUD and other micro-gasification is currently known."   
Maybe it is now 25%???   Certainly not 40% or more.   So much to do!

And be sure to keep us all well informed.   When appropriate, there are 
websites (mine for drtlud.com and the one for Stoves) what are available 
to place more substantial documents.   But for the time being, keep the 
discussion going on the Stoves Listserv.

Best wishes,

Paul

Paul S. Anderson, PhD  aka "Dr TLUD"
Email:  psanders at ilstu.edu   Skype: paultlud  Phone: +1-309-452-7072
Website:  www.drtlud.com

On 4/4/2013 9:40 PM, Crispin Pemberton-Pigott wrote:
> Dear Julien
>
> Crispin offered me the following advice for burning wheat straw in a
> gasifier cookstove:
>
>> "It sounds like you could afford to reduce the primary air supply. If you
> have things right you should be able to turn it off completely. If you are
> able to generate a condition that is primary-air-starved, you can then
> regulate it."
>
>> Following that advice, I packed the paint can with as much straw as I
> could.  I put the can on top a paint-can lid which blocked off all primary
> air.
>
> That is a good example of total control.
>
> Now you can make a controllable hole that allows you to admit a lot of air
> (whatever that means) to get it lighted and then restrict it to an
> appropriate level. The result will be continuous gas production.
>
> How much air later? At that size I would guess 1 or 6 holes 6mm diameter but
> Paul Anderson should comment here. He built these 10 years ago and have
> little tubes coming out the side with several small holes which he could
> close individually with tape.
>
> The point is to explore the relationship between primary air supply and the
> production of burnable gases.
>
> Because the weather is still cold it is hard to know if what you were trying
> to ignite was steam (or how much was steam) and how much was smoke. If it
> was not pyrolysing at a high enough rate the secondary air may have diluted
> it below the concentration needed for ignition.
>
> The news is that you went from a 5 minute burn to more than an hour. Next
> you need to get the burn you want which will be in between. The primary air
> supply is all the difference. The secondary air needed depends on the gas
> production rate.
>
> It is not all that complicated. The vast majority of stoves have far too
> much excess air at the primary and secondary level so the first thing to get
> a grip on is the air/fuel ratio (just like a car engine which is why
> combustion analysers report the air/fuel ratio).
>
> Regards
> Crispin
>
>
>
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