A standard burn for version 1.0 took an unexpected turn, likely due to the wear of high heat on some of the structural steel.
We loaded the retort with some excellent construction cut offs, this time thanks to Tim and his crew at Bayshore Construction Inc., and sealed it up as usual. The one difference we noted was that the lower lid and support bars were quite warped from the previous burn and the whole bottom assembly was about two inches lower in the centre before lighting. Instead of fixing the problem completely, we had only slightly corrected the warp and went ahead with the burn which meant it could warp even further than before.
Sealed with soil after the burn, preventing oxygen from entering the retort chamber
The burn went well, the fuel wood was very dry and all seemed well. While it cooked, I had time for “bush forging” a copper bracelet and pendant and Neido~chan made a pair of custom copper keyrings. After the burn was complete, soil was used to seal off the drum as much as possible for cooling.
Blocking the top seal with soil and the rocket combustion chamber outlet with a disc plate
The next morning’s inspection revealed that the damage to the lower lid assembly was extensive. Though it was long after cooling should have been complete, and despite a morning rain shower, the drum was still warm to the touch. Upon opening it quickly became evident that a good portion of the charcoal had burned off at some point and that some of it was still possibly smouldering.
The sagging gravity-forged support bars and lower lid after two firings. Note the large air gaps
With the breath of fresh air, it quickly reignited into a hot red flame, threatening to consume the remainder of the yield from the previous day. I quickly dumped the drum onto the ground and spread out the charcoal to put out the flame and save as much as possible. The flames went out and most of what was left was fine. After it cooled for a few hours in the misty rain, we chopped and sorted as usual, checking carefully for remaining heat and embers.
A quick dump of the retort contents prevented a fire and loss of the day’s yield
Though we are not sure if the charcoal was consumed mainly during the burn or during the cooling period, it seems likely that the combustion rather than pyrolosis of the internal charcoal wood was due to the decreased seal around the lower lid. Prudence dictates that putting energy into a version 2.0 is the next goal, using what we have learned and modifying for high temperature operation. We will need some heavier plate steel and perhaps some willing individuals to weld and cut, or a new Multiplaz for the island workshop.
Find out about the construction and operation of our new and improved charcoal kiln: Charcoal Kiln V.3