[Stoves] Oil drum based TLUD for biochar production and water heating

[Darren]

Looking to work on a TLUD design based on a standard oil drum (200-litre 
drum (known as a 55-gallon drum in the United States and a 44-gallon 
drum in the United Kingdom) to produce biochar from well dried wood.

Ideally the stove would have a short chimney so as not to be too high so 
that a pot/water tank/oven could be placed above the stove to be 
directly heated by the flames.

I've had a look about on the internet to see what people have been 
building - almost all appear to have an extra 1/3rd of a drum on top as 
an 'afterburner' chamber and a reasonably long chimney on top of this.  
Making them rather tall for easily positioning oven/watertank/pots for 
direct flame heating.

None I have seen have an extra, large metal skin / tube surrounding the 
barrel to provide secondary air pre heating (as is done with some 
smaller TLUD designs).  I wonder if adding this could reduce the total 
working height of the stove.

Looking to make something that is nice and clean burning.

Current ideas include -

* positioning the chimney/riser at one side of the barrel to allow 
heating on the rest of the metal surface next to the riser - although I 
suspect a large diameter chimney is required, leaving a hot surface of 
limited size.

* charging the barrel 2/3rds full with fuel leaving the top 1/3rd empty 
as an 'afterburner' - having secondary air holes positioned to jet in 
air at this height.

Interested in any thoughts people have or any efforts people know of oil 
drum TLUD designs where people are trying to reduce the height, use the 
heat, or provide heated secondary air.

Best

Darren

see our previous biochar stove at 
http://www.appropedia.org/Forest_biochar_rocket_stove

.