stove-image: 

Mussie T. (Lecturer at Mekelle University, Ethiopia), October, 2011

This is a Natural Draft Gasifier stove, that is designed with a central column of air that is designed to burn more common Ethopian fuels, e.g. coffee husk and saw-dust (cow dung binder) briquettes in addition to more conventional wood chips.

the air column is drilled on the surface so as to let additional primary air radially into the fuel at different stages to compensate for air clotting that can occur when run with small sized fuel as you go up from along fuel column. This helps the flaming pyrolysis from being air starved due to interlocking of fuel particles. In addition to that, closely spaced holes of relatively larger size were made near the top of the central air column to supply more hot post‐pyrolysis secondary air. The presence of two hot secondary air admission points is meant to supply enough air while keeping the stove short with reduced heat loss.

Once the stove has enough fuel, it is typically started with wood chips, or an accelerant to help the briquettes light, and then in all of the trials it burned without smoke until the fuel tank was filled with charcoal (typically between 60 and 90 minutes later). This is a biochar-producing stove, the stove does not efficiently combust it. Friability and the composition of the char depended upon the feedstocks.

For an excellent analysis of the stove, and pictures of the biochar, please see the included Report: Results from Preliminary Experiments Conducted on Multi‐level
Primary Air Entry Gasifier Stove

Biochar Industries part of Biochar Project in Kunghur Australia is now selling Biochar TLUD cook stoves as part of our plan to make more people aware of the benefits of biochar.

T l u d

is an acronym for Top Lit Up Draught meaning you lite it at the top and the air is sucked up through the fire. Fantastic device that is light to carry and will work with all woods great survival tool . The best feature of this Tlud is when the flames go out you then have biochar. All you have to do is drop the embers on the ground and spray some water on them so they don’t continue to burn.

This particular model was imported from India and has a very nice finish and somehow I ended up with some to sell so I wanted to let my readers know first before I start selling them at stores and markets.

The aim of this test was to finalise the design of the Anila stove, which had been produced in India ready for distribution to households to gather feedback from them about usability.
This is for the project: http://biocharinnovation.wordpress.com/

Without wanting to change the design too much from the original plans, the following changes were deemed necessary –

I learned to make TLUDs from Dr. Paul Anderson when he came to do a stove & biochar demonstration for Biochar Ontario in June 2009. Since my primary interest was in producing biochar, I went home and began building a larger version of the “Champion” TLUD stove from a 55 gallon drum and a 25 gallon drum (pictured above.) I have been following this list since then and on “Dr. TLUD’s” urging, I thought should begin sharing with this community what I have been learning.

The “Large TLUD”

Essentially a "beefed up" version of the Champion TLUD Stove, my large TLUD has worked beautifully from the first trial run. The pyrolysis process is extremely clean in terms of visible emissions and can produce 25 – 30 liters (6 – 8 gallons) of biochar per run depending on feedstock. To halt the pyrolysis process to retain the biochar I have always used a watering can to quench the glowing coals. Two to four gallons of water usually does the trick.

Using this stove, I have pyrolyzed a number of different types of feedstock including: scraps of spruce lumber, pine needles, pine cones, pine bark, corn cobs, chicken litter, and hardwood sawdust pellets. The successful pyrolysis of the various feedstock has always depended on (no surprise here) having dry feedstock with pyrolysis times ranging from one to two + hours (again, depending on feedstock.)

Until recently I had been using a hardware store woodstove thermometer on the top of the stove.
I estimated pyroloysis temperatures to be in the 350-450 C range. I began using a 12vdc computer cooling fan to shorten run times and boost temperatures closer to 500 C. I recently acquired a temperature data logger and found, to my surprise, that temperature quickly shot to over 800 C with the fan. Even without the fan, temperatures in and above the pyrolysis front were between 600 and 750 C. The data from the first run with the data logger is attached. *Note:T1 is the thermocouple near the top of the inner fuel barrel just below the top of the feedstck and T2 is the thermocouple about 2 inches above the bottom of the inner fuel barrel.

My next steps are to monitor temperatures while experimenting with choking the primary air to different degrees and as I gain better control of pyrolysis temperatures, to (further) experiment with various types of feedstock. I am also working on a simple system to use the pyrolysis heat to dry feedstock.
I will post my results here.