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FLAME CARBONIZERS FOR BIOCHAR
Kelpie Wilson
Wilson Biochar Associates
kelpiew@gmail.com
In Practice and Theory
Japanese Cone Kiln – Moki Co.
Our inspiration comes from Japan where these simple cone-shaped
kilns were developed and sol...
Flame as Heat Exchanger
With the pan excluding air from the bottom and the flame
excluding air from the top, the Flame Cap...
Limits of Heat Transfer through Metal
In theory, Stirling Cycle engines approach Carnot efficiency. In practice,
exergy lo...
Basic Flame Types
• Flames can be divided into categories:
• Pre-mixed vs Diffusion
• Laminar vs Turbulent
• Concurrent fl...
Concurrent Axial Flow
• No external limits on air
entrainment
• Lean mixture cools the
flame, producing soot
• Flame lengt...
Counterflow combustion laminar flame
For Best Heat Transfer:
Shorten the Flame Length
• Flame length is a function of mass flow rate and fuel bed
diameter
• Op...
Flame Carbonizer Flame Types
• TLUDs* and Ricks
• Con-current Axial Flow
• Flame Kilns
• Shallow Kilns
• Cross-current vor...
Ways to Tame a Flame
Jack Daniels Rick – with Hood
The Jack Daniels Company has made charcoal for
filtering whisky this way for decades. When t...
Optimizing TLUDs as Flame Carbonizers
• TLUDs are Flame
Carbonizers
• Not very different from
a rick in a cylinder
Design ...
Rick inside a ring - Ring of Fire
If bottom is not sealed, can burn like a TLUD. Can operate in dual mode:
• TLUD for star...
Deep Kiln - Counter-current flow
• Passive counter-current flow as burning fuel draws air downward
• Active counter-curren...
Ring of Fire Kiln - vortex generation
Reflected (re-radiated) heat and thermal gradients
produce vortex flows
Kon Tiki – cross-current vortex generation
Rim shield around the cone draws air to feed the flames, generating
cross-curre...
Flame Carbonizers vs Pile Burning:
The Fuel Problem in Oregon
Tight pile construction is standard
• Tight piles don’t fall apart
• Burn hot in the center
• Burn completely to ash
• Gen...
Top lit makes a difference
But to save any char you need water to quench
Very Loose Open Pile – Top Lit
Concurrent axial flow – burns fast, hot and clean, but pile falls
apart and needs tending. ...
Open Ricks
Rick in Pan
Design Parameters for Oregon Kiln
• Sized for feedstock
• Logs 4 to 5 feet long
• Up to 6” diameter
• Log rick fits better...
Oregon Kiln
Oregon Kiln in the Backyard
Oregon Kiln in the Woods
Grayback Forestry Crew
Working in the Rain
Dumping
Time and Water Needed to Quench
Willow Witt Ranch
Quenching Time
Using the jib crane to dump
Next Christmas…
Giant Slash Pile
It’s a HUGE problem! We need bigger kilns, but they need to be
mobile.
Air Curtain Burner – Counter-flow
Active counter-current flow using a blower
Air Burner with blower off – like Deep Kiln
Air Burner Biochar - Ashland Watershed
Air Burner Char
Air Burner Char
Left: char chunks. Right: mineral soil
Trees planted in Air Burner char
Left: light granitic soil. Right: soil with char mixed in.
More Ideas for Flame Carbonizing
Burner Design – tangential air & baffles
Burner Design – Electromagnetism
Controlling the flame with an electromagnetic field
Burner Design - Coanda Effect
Can we create curved surfaces that exploit the Coanda Effect?
Container Design -Tents and Wigwams
Left: Carbon Cultures biochar kiln.
Right: WigWam biochar kiln by Scott McKain of UBET
Container Design – Coking Ovens
Non-Recovery Coking Oven
Channels flue gas underneath for more heat transfer
Container Design - Cob Ovens
Make a little biochar with your pizza or make a little pizza
with your biochar!
Wilson Biochar
Associates
Wilson Biochar Associates specializes
in biochar technology and market
development. We provide s...
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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. 1. FLAME CARBONIZERS FOR BIOCHAR Kelpie Wilson Wilson Biochar Associates kelpiew@gmail.com In Practice and Theory
  2. 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. 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. 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. 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. 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. 7. Counterflow combustion laminar flame
  8. 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. 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. 10. Ways to Tame a Flame
  11. 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. 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. 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. 14. Deep Kiln - Counter-current flow • Passive counter-current flow as burning fuel draws air downward • Active counter-current flow uses a blower
  15. 15. Ring of Fire Kiln - vortex generation Reflected (re-radiated) heat and thermal gradients produce vortex flows
  16. 16. Kon Tiki – cross-current vortex generation Rim shield around the cone draws air to feed the flames, generating cross-current vortex flows
  17. 17. Flame Carbonizers vs Pile Burning: The Fuel Problem in Oregon
  18. 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. 19. Top lit makes a difference But to save any char you need water to quench
  20. 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. 21. Open Ricks
  22. 22. Rick in Pan
  23. 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. 24. Oregon Kiln
  25. 25. Oregon Kiln in the Backyard
  26. 26. Oregon Kiln in the Woods
  27. 27. Grayback Forestry Crew
  28. 28. Working in the Rain
  29. 29. Dumping
  30. 30. Time and Water Needed to Quench
  31. 31. Willow Witt Ranch
  32. 32. Quenching Time
  33. 33. Using the jib crane to dump
  34. 34. Next Christmas…
  35. 35. Giant Slash Pile It’s a HUGE problem! We need bigger kilns, but they need to be mobile.
  36. 36. Air Curtain Burner – Counter-flow Active counter-current flow using a blower
  37. 37. Air Burner with blower off – like Deep Kiln
  38. 38. Air Burner Biochar - Ashland Watershed
  39. 39. Air Burner Char
  40. 40. Air Burner Char Left: char chunks. Right: mineral soil
  41. 41. Trees planted in Air Burner char Left: light granitic soil. Right: soil with char mixed in.
  42. 42. More Ideas for Flame Carbonizing
  43. 43. Burner Design – tangential air & baffles
  44. 44. Burner Design – Electromagnetism Controlling the flame with an electromagnetic field
  45. 45. Burner Design - Coanda Effect Can we create curved surfaces that exploit the Coanda Effect?
  46. 46. Container Design -Tents and Wigwams Left: Carbon Cultures biochar kiln. Right: WigWam biochar kiln by Scott McKain of UBET
  47. 47. Container Design – Coking Ovens
  48. 48. Non-Recovery Coking Oven Channels flue gas underneath for more heat transfer
  49. 49. Container Design - Cob Ovens Make a little biochar with your pizza or make a little pizza with your biochar!
  50. 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.

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