[Stoves] DIY camping TLUD with walnut shell fuel

[neiltm at uwclub.net]

On 13 Jun 2016 at 9:28, Mangolazi wrote:

> Hi everyone,
> 
> I've been messing around with a tiny gasifier based on a peach can
> for camping usage. I can get about 12 minutes flame time using
> twigs, although the coals inside keep burning for a lot longer. I
> can boil 500 ml water in 7 minutes using twigs. 
> 
> I recently added an outer vessel for windproofing and to preheat the
> secondary air. Using walnut shells, I get a very hot and high flame,
> higher than with peanut shells or twigs, with flames reaching almost
> to the top of the pot. Total flame time goes up to 14 minutes and
> 500 ml water boils in 6 minutes, faster than before. Please see
> attached images. 
> 
> How can I prevent the flame from going up so high? 
> 

I solve this problem by varying the fuel.  Try adding thicker pieces of 
wood or damper wood, but mixed up with the shells, not layered.  Layered 
will likely create smoke and maybe extinguish the flame.   

> Is it possible and feasible to throttle primary air on such small
> stoves? 
> 

I haven't found a way.  I tried cutting a disc of stainless steel and 
making holes to match the ones in the base, such that I could 
progressively turn the disc to close off the primary air, or most of it, 
but I found it impossible to make the holes and retain a flat enough 
undistorted disc after the drilling.  When placed in the bottom it became 

clear that air would find its way around the sides of the disc not lying 
sufficiently flush to the base, largely negating any blanking effect, so 
I abandoned the project.  Someone with more refined tincanium fettling 
skills than I possess may manage something though.  The idea was to have 
a tab extend from the disc through a slot cut in the outer can in order 
to regulate the air during the burn.

A simpler, but fixed for that burn possibility might be to place some 
washers over the primary air holes at the bottom of the can to restrict 
the primary air, but I have not tried this since I find varying the fuel 
the most satisfying solution to 'turn down'. When I'm camping it seems 
easy to find sufficiently variable fuel to achieve the fire I want and 
experience teaches how to do this and is very satisfying when you get it 
just right.  After about 20 minutes or so, ash accumulates to the extent 
that the primary air holes get increasingly blocked, and by varying the 
amount of riddling with a stick you can also control the primary air that 

way.  This can be a useful way to achieve a simmer, after a rapid boil, 
but it is easy to lose the flame if you don't riddle.  Practice, keen 
observation and continuous experiment teaches how to get what you want 
from these stoves, but I still make the occasional smokey mess.

Just spent five days in wet Wales doing just fine with cooking and 
brewing on wood.

Neil Taylor


> Has anyone used peanut or walnut shells for daily cooking on a large
> TLUD? 

Not that large, unless the Reed XL counts as large?
I've used pistachio shells successfully, and since moving a garden shed 
and uncovering a barrow full of mouse opened plum stones, nicely dried, I 

have been finding these a robust, longer life fuel on their own, albeit 
harder to light off initially.  They sometimes get added to the mix now 
instead of or with damper wood when I want something less than a towering 

inferno.

Although I have made quite a few tincanium microgasifier ND TLUDs I now 
use the cheap chinese wood gas stoves sold on ebay for 10 UK pounds or 
thereabouts as they are so well made and pack to less than half their 
operating size into a small  billy can in seconds.  They are really 
excellent - I would say optimal in design for camping use, especially 
when finding fuel in wetter climates like the UK.  With little or no 
moisture in the fuel the burn can be towering and last about 10 minutes, 
and boil a full kettle in that time, but the up side is that if the fuel 
is damper, a good burn is still achievable, and more useful for most 
cooking, and usually much less smokey.  They are also just as useful used 

conventionally, not as a TLUD, but also easily transition from TLUD to  
continuous feed to extend the burn. The char is being consumed so quickly 

that a fresh fire is easily revived from the char stage provided it 
hasn't all been consumed of course. With a large amount of primary air, 
adding fuel makes less smoke than with the cleaner emissions 1 to 6 
primary to secondary air ratios such as the Reed fan Woodgas campstoves.  

No reason though why you shouldn't obtain the same versatility from a 
home made tin can stove.  Most of the ones I made aimed for the cleaner 
burn with the 1 to 6 ratio or thereabouts, but it made them harder to use 

and fuel fussy.  Just put a 'grate' rather than a restricted base in and 
vary the fuel, and you should find your camp stove relatively easy to get 

and keep going.  You get soot on the pot, but that is easily wiped off, 
leaving a black finish that then goes in a plastic bag to keep it to 
itself.

Have fun :)

Best wishes,  Neil Taylor

> 
> Thanks!