The 'SuperBoo' TLUD kiln, built with a 1m length of 6" 304 1.6mm exhaust tube, using the whole length.

A 100mm grinder with a 2.5mm thick disc used to grind 3 rows of primary air slots at the base and one upper row of secondary air slots, 250mm below the top.

Dry thin bamboo at 70cm lengths were vertically stacked beneath the secondary air slots.

'Waste' bamboo leaf and stem plus a small dose of firelighter gel used to top light the burn.

You definitely want this TLUD wind protected and operated on a calm day even though the base seemed to be stable - you never know - it could tip over - plus clear at least a couple of metres around the base and above the kiln, removing flammable debris. Plus, it shouldn't be operated during bushfire season.

Burn time was 42 minutes.

When the main flame went out, a watering can was used to pour water from the top with a surprising small amount of steam generated.

Once quenched, wearing welders gloves I used the external prongs of a 6" chimney flue bracket to carefully raise the main tube and empty the char onto the bottom collector pan filled with water from the top quench.

99% biochar recovery which I would call a success!

I'd also add that this bamboo biochar Inertinite appears to be of very high quality (research) - perfect for water filtration and possibly for Atmospheric Water Harvesting (AWH).

 

If 6" exhaust tube can't be accessed, is too expensive or is too small, then large diameter Carbon steel tubes could be a better option and are probably in more places. These would also be suitable for larger bamboo culms.

I'm betting a similar slot arrangement for primary and secondary air will work with the larger tubes - as long as there is enough 'UpDraft'.