Thursday, August 14, 2008

Larger 20-gallon charcoal making retort, burn 1

Flush with overconfidence from my half-gallon prototype, I went ahead and made a full-size version of Mighty Gunther's Backyard Charcoal Retort, with some minor modifications.

His web site pictures a thirty-gallon barrel inside an open-top 55-gallon barrel.  Rumor had it that burn barrels are illegal here.  While this is a charcoal retort and not a burn barrel, it would look a lot like a burn barrel in operation, so I cut the bottom off my barrel and attached a chimney to it, which should incontrovertibly make it a stove.  With no bottom, it was easier to set it up on fire bricks to allow combustion air to enter rather than punching holes in the side.

I went to three junkyards and could not find a 30 gallon metal barrel, so I bought a brand new shiny 20-gallon trashcan.  I stuffed it with flax straw as tight as I could by jumping up and down on it, put the lid on and put it upside down on the ground inside the large barrel.

I put scrap lumber chunks around the bottom to about a third of the way up, and filled the rest of the gap and the head space with flax straw, not too tight.

I lit the top and waited until it was burning all the way across before putting the lid on.  It didn't fit as well as when it was cool, consarnit.  Treebeard and I tried to insulate the outside with regular fiberglas insulation, but it got hot enough to slag it and it melted partway off.

I figured the gas would escape around the trash can lid but instead it burst the side seam!  There was an audible hissing during the burn.

The outside fuel burned completely.

The straw inside mostly cooked into charcoal except at the bottom, which was right on the ground.

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