Not mine, but I like it based on what you said elsewhere. Thoughts? https://www.instructables.com/id/Building-A-Rocket-Stove-For-The-Cabin/
For me the rubbish bin would rust out in 6 months because of the sea air. I dont need my one to be mobile I would be collecting stainless steel,masonry and perlite to build my one. I liked the insulated pipe idea and would insulate a pipe within a masonry box. Just like that one Making that pipe SS means its permanent. I also want it at hip high for convenience.
I'll email him. Last I heard, which was today, he is working on a redesign of a rocket stove bbq and a char maker based off a Japanese design for bamboo. And trying to get ready for the BOGI Fair, and running his gasifier business I suppose. I scored an old stainless steel urn which will make a good outer skin for one, I would assume.: View attachment 2697
Perlite or vermiculite both make for good cheap insulation materials, ag lime is also good to use but would make the unit much heavier. You don't need that much insulation as a general rule Perlite or vermiculite 100mm is fine, I use 100mm on one of my gasifers which runs 600-700 deg C. I wouldn't bother with the second inner pipe as it has no real value to the design. The Bin could be made from many things, old 20lt paint can or even some thin gal sheet which could be rolled and screwed in shape. The inner pipe is what is exposed to heat and is a corrosive environment. That steel pipe he used might last a year or so, a stainless steel pipe would last much longer. You could use square section or even old square down pipe as the inner pipe, but it would have a limited life. One thing I did not like was the exposed vermiculite at the top, both perlite or vermiculite are dusty and not capping/sealing them is a mistake I would avoid. It would also suck up any fats that dip into it which may be a fire hazard down the track.
would take perlite over vermiculite any time. vermiculite has some asbestos risk. perlite is glass fluffed with air.
Not sure how the cob would deal with the changes in heat and it might crack if moved where the concrete might hold up better with movement. I'm not that well versed in cob construction sorry. Try one and let us know how you go. =)