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

[Paul Anderson]

Julien,

If you bottom light the 30 gal with straw and some vertical passages, be 
aware that the initial heat energy goes into drying any of the straw 
above it.   That means much moisture (and little chance of it igniting) 
in the first minutes.   You will probably get the firemen to visit 
you.   Be careful.

Your trial with a single central air column is the same as the well 
known packing of sawdust into a similar arrangement.

The above are not my specialty, so I have little else to add.

For TLUD trials, straw that is cut and kept straight (not crushed and 
matted) and placed vertically in a TLUD should work.   But the issue is 
how much pushing together can be done before the needed primary air flow 
is uniformly blocked (which is not bad if then use a fan to power the 
air through it, as done with rice husks), OR if it is blocked is some 
places and somewhat open in others (which is bad because the fire will 
channel down to the bottom.)

I suggest you try the vertical straw rather loose.   Expect a short 
burn.   Note:   Make the bundle tight with a string, insert, and remove 
the string so that the bundle expands to fill the whole diameter of the 
fuel chamber.  That is what Paal Wendelbo taught us to do with the more 
"reedy" grasses.

Good luck and let us know what happens.

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 4/9/2013 4:03 PM, Julien Winter wrote:
>> Lanny Henson Tue Apr 9 12:58:26 MDT 2013  wrote:
>> Julien,
>> Have you tried top lighting the 30 gal drum of straw?
>> Do you have problems maintaining an open, central, air flow, pathway?
>> Lanny
>
> Lanny;
>
> I did not try top lighting the 30 gal drum with a hollow core in the
> bed of straw.   That is probably worth trying, but the paint can tests
> suggest that it may not work if the reaction is in TLUD mode.
>
> I have not had trouble with the central hole in a bed of straw
> collapsing during a burn.  Gasified straw maintained its structure,
> even though it had lost ca. 80% of its mass.
>
> I think my next move is to bottom light a 30 gal bed of straw
> containing multiple vertical holes, to see if I can shorten the path
> length for the convection of gases and heat.  If I can get that to
> work, I will try top lighting it as a TLUD.  I like the TLUD process
> in theory, because the oxygen is used up in the descending ignition
> fire, and not in ashing charcoal, as occurs with bottom lighting.
>
> However, I will not be running any more trials for a week, because we
> have rain and possibly snow in the forecast.
>
> I find that a paint can reactor is a fairly good model for a 30 gal
> drum reactor.  I can easily test equipment designs, fuels and
> procedures.  I can run several trials in an hour and not use too much
> feedstock, and I can run replicates to be sure.  I can also run
> special photo-ops, such as in the dark.  If a paint can trial is a
> failure and I have to put it out, I don't have to dispose of much
> waste straw.  By contrast, a run of the 30 gal reactor can take a
> couple of hours, plus, if it goes really badly and I create heaps of
> smoke, I could be visited by the city fire brigade.  Alas, I am not
> working in a farmyard, but in a suburbia.  One-upon-a-time, my family
> used to collect cows, but not any more.
>
> Thanks to all for the input,
> cheers,
> Julien.
>
>
>
>
>
> --
> Julien Winter
> Cobourg, ON, CANADA
>
> _______________________________________________
> Stoves mailing list
>
> to Send a Message to the list, use the email address
> stoves at lists.bioenergylists.org
>
> to UNSUBSCRIBE or Change your List Settings use the web page
> http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylists.org
>
> for more Biomass Cooking Stoves,  News and Information see our web site:
> http://stoves.bioenergylists.org/
>