At an incipient stage of development of the biochar industry, small property holders, farmers and gardeners around the world seek to process their locally available waste biomass into biochars suitable to enhance their soils, with modest budgets in the $100’s to $10,000 range. Much of the potential supply of feedstock is thinly distributed on small properties and local scales, and requires small-scale, hands-on processing. Yet small-scale designs that are promulgated on the Internet and in workshops have often been crude, complex to the initiate, smoky, ineffective in practice or in dealing with mixed feedstocks, and unlikely to replicate to impactful degree. The deep cone Kon-Tiki kiln was developed in Jul 2014 to answer this need. Since then Kon-Tiki kilns have been built or marketed in 57 countries. This presentation reports on the developments of deep-cone Kon-Tiki kilns, to evaluate the best design parameters and operation for efficient clean biochar making, and pre- and post-treatment. Data are presented on emissions, char quality, field trials, and extension of the design concepts to farm and commercial-scale batch and continuous pyrolysis machines. 12,400L of biochar was made in a 1.65m diameter Kon-Tiki, with overall volume and mass yield from the original wood biomass of 44% and 17% respectively. Six different biochar mixes were prepared, including biochar mineral complexes made in retorts heated within the Kon-Tiki, for a farm-scale trial on 28 x 200m broccolini beds. Cylindrical, and pit kilns were also compared with the Kon-Tiki for processing greenwaste. In further work the original deep cone Kon-Tiki concept, with cylindrical heat shield, was varied to study a double cone kiln, a 2.5m diameter shallow cone, and a 0.7m small cone, to compare convection dynamics and efficiency. The flame curtain kilns emitted significantly lower emissions than other simple batch kilns.
Paul Taylor
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