Flame Carbonizers for Biochar In Practice and Theory
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You can make biochar with a simple cone or ring kiln, but how does it work? This presentation explains the principles behind flame carbonizing - using an open flame to produce charcoal from biomass.
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Flame Carbonizers for Biochar In Practice and Theory
- 1. FLAME CARBONIZERS FOR BIOCHAR Kelpie Wilson Wilson Biochar Associates kelpiew@gmail.com In Practice and Theory
- 2. Japanese Cone Kiln – Moki Co. Our inspiration comes from Japan where these simple cone-shaped kilns were developed and sold by the Moki Company. They are bottomless, and you simply roll them away when you are done.
- 3. Flame as Heat Exchanger With the pan excluding air from the bottom and the flame excluding air from the top, the Flame Cap Kiln acts like a retort with the flame as a heat exchanger – transferring heat efficiently by radiation.
- 4. Limits of Heat Transfer through Metal In theory, Stirling Cycle engines approach Carnot efficiency. In practice, exergy loss from heat transfer across metal reduces efficiency. That’s why we use the internal combustion engine, despite its lower theoretical efficiency. For similar reasons we may prefer a flame carbonizer to an externally heated retort
- 5. Basic Flame Types • Flames can be divided into categories: • Pre-mixed vs Diffusion • Laminar vs Turbulent • Concurrent flow (axial) vs Counter-current flow or Cross-current flow The cone kiln works with cross- current flow that generates counter- current vortex flows
- 6. Concurrent Axial Flow • No external limits on air entrainment • Lean mixture cools the flame, producing soot • Flame length limits radiative heat transfer to fuel bed
- 7. Counterflow combustion laminar flame
- 8. For Best Heat Transfer: Shorten the Flame Length • Flame length is a function of mass flow rate and fuel bed diameter • Open sided piles entrain more air than enclosed piles – giving higher air mass flow rate and higher flame length • High flow rate flames cool faster and radiate less heat to the fuel bed • Piles enclosed by a surrounding cylinder have shorter, more turbulent flames due to less entrained air Buoyant diffusion flames: Some measurements of air entrainment, heat transfer and flame merging. Thomas, et al. Fire Research Note. 1964
- 9. Flame Carbonizer Flame Types • TLUDs* and Ricks • Con-current Axial Flow • Flame Kilns • Shallow Kilns • Cross-current vortex generation • Deep Kilns • Passive Counter-current flow • Air Burners • Active Counter-current flow • *TLUD: Top-Lit Up-Draft gasifier
- 10. Ways to Tame a Flame
- 11. Jack Daniels Rick – with Hood The Jack Daniels Company has made charcoal for filtering whisky this way for decades. When the rick collapses into glowing coals, they quench it with water
- 12. Optimizing TLUDs as Flame Carbonizers • TLUDs are Flame Carbonizers • Not very different from a rick in a cylinder Design Parameters: • Primary Air • Secondary Air • Flame stabilization with swirl or tertiary air • Burner plenum space • Stack effects
- 13. Rick inside a ring - Ring of Fire If bottom is not sealed, can burn like a TLUD. Can operate in dual mode: • TLUD for startup • Deep Kiln for later stages
- 14. Deep Kiln - Counter-current flow • Passive counter-current flow as burning fuel draws air downward • Active counter-current flow uses a blower
- 15. Ring of Fire Kiln - vortex generation Reflected (re-radiated) heat and thermal gradients produce vortex flows
- 16. Kon Tiki – cross-current vortex generation Rim shield around the cone draws air to feed the flames, generating cross-current vortex flows
- 17. Flame Carbonizers vs Pile Burning: The Fuel Problem in Oregon
- 18. Tight pile construction is standard • Tight piles don’t fall apart • Burn hot in the center • Burn completely to ash • Generate smoke • Burn forest soil
- 19. Top lit makes a difference But to save any char you need water to quench
- 20. Very Loose Open Pile – Top Lit Concurrent axial flow – burns fast, hot and clean, but pile falls apart and needs tending. Can make a lot of biochar if quenched.
- 21. Open Ricks
- 22. Rick in Pan
- 23. Design Parameters for Oregon Kiln • Sized for feedstock • Logs 4 to 5 feet long • Up to 6” diameter • Log rick fits better in pyramid shape than cone • Portable but Durable • Less than 200 lbs • 14 gauge steel • Ergonomic for loading • Only 2 feet high • Economical • Pyramid shape cheaper to fabricate than cone • $600 for Kiln – 5’ top base, 4’ bottom base, 2’ high
- 24. Oregon Kiln
- 25. Oregon Kiln in the Backyard
- 26. Oregon Kiln in the Woods
- 28. Working in the Rain
- 29. Dumping
- 30. Time and Water Needed to Quench
- 32. Quenching Time
- 33. Using the jib crane to dump
- 34. Next Christmas…
- 35. Giant Slash Pile It’s a HUGE problem! We need bigger kilns, but they need to be mobile.
- 36. Air Curtain Burner – Counter-flow Active counter-current flow using a blower
- 37. Air Burner with blower off – like Deep Kiln
- 38. Air Burner Biochar - Ashland Watershed
- 39. Air Burner Char
- 40. Air Burner Char Left: char chunks. Right: mineral soil
- 41. Trees planted in Air Burner char Left: light granitic soil. Right: soil with char mixed in.
- 42. More Ideas for Flame Carbonizing
- 43. Burner Design – tangential air & baffles
- 44. Burner Design – Electromagnetism Controlling the flame with an electromagnetic field
- 45. Burner Design - Coanda Effect Can we create curved surfaces that exploit the Coanda Effect?
- 46. Container Design -Tents and Wigwams Left: Carbon Cultures biochar kiln. Right: WigWam biochar kiln by Scott McKain of UBET
- 47. Container Design – Coking Ovens
- 48. Non-Recovery Coking Oven Channels flue gas underneath for more heat transfer
- 49. Container Design - Cob Ovens Make a little biochar with your pizza or make a little pizza with your biochar!
- 50. Wilson Biochar Associates Wilson Biochar Associates specializes in biochar technology and market development. We provide strategic advice and services to businesses and organizations. • Technology Assessment • Research and Analysis • Project Development Kelpie Wilson Wilson Biochar Associates Home office: 541-592-3083 Mobile: 541-218-9890 kelpiew@gmail.com www.wilsonbiochar.com Wilson, K. & Perkins, C. (1987). Approximating the Ideal Stirling Cycle Through Discontinuous Motion of the Displacer Piston. Senior Project Report and Second Prize Winner, ASME Power Division, Student Paper Competition. Kelpie Wilson and Carol Ann Perkins with Stirling Engine at CSU, Chico.