Portable Kon-Tiki Kiln; A Low Cost Low Emissions Kiln

for Producing High temperature Biochar and

Low Temperature Biochar Mineral Complexes

History 1. Cone kilns were originally developed in Japan 2. Present modifications come from Hans Peter Schmidt and Paul Taylor 3. Testing work and quenching with mineral and organic matter from Paul Taylor and

Stephen Joseph

1. Can be made cheaply and can produce a range of different biochars 2. Various sizes of above and in ground units 3. Heat shield makes it safe 4. For woody biomass emissions are low and yield between 17%-20% 5. Easy to fill, start, operate, quench and unload 6. But needs continuous filling of woody biomass 7. Easy to quench by flooding the bottom of the reactor and filling with mixture of organic

matter, cay and mineral matter (slide 8). 8. Spray at top can help regulate temperatures an increase surface porosity 9. Temperatures are high (>600C) and yield low 10. Not recommended for rice husk and rice straw unless placed in barrels that are put in

the kiln (slide 5)

Portable Kon-Tiki Kiln

1.65m Cone (maximum) out of two 1.2 x 2.4m sheet with H=90cm

1650 mm 9

00

m

m

64.5o

Volume = 1097 L

(Scale 10%)

Water Spray for Temperature control and Increasing surface porposity

780

67

5.5

420

1200

60 deg Volume cone = 375.0 L

Template for maximum cone out of 2.4 x 1.2 m sheet (with maximum base (420mm) out of corner)

2400 1

20

0

Volume = 375 L

Scale 10%

420

Making These More Complex Formulations in Kon-Tiki with Barrels

to Produce a high temperature woody biochar and low temperature

straw/husk manure biochar in drums

In Ground Cone Kiln can make 180kg in 8-10hrs

Bring kiln to the biomass

Clean burning

in 5-10 minutes

Time Stack T NOx CO Comment 10:04 261 41 429 10:09 186 22 380 11:05 49 0 429 spray 12:00 141 9 247

2.44 121 8 362 closed gap

4:00 205 13 232 4:10 210 15 297 4:30 127 6 580 spray

EMISSIONS MEASUREMENTS Hood is only to

capture emissions

Results:

NOx low

CO relatively low

No significant improvement by enclosing kiln

Water mist increased CO

Once Kiln has been half to ¾ filled with biochar it can be quenched with a mixture high in organic nitrogen and minerals to promote

growth of beneficial micro-organisms. Note we covered the biomass clay mixture with biochar to capture any smoke that came

off but we didn’t see anyything

Ingredients:

• 30kg dry lantana vine

• 30kg of palm tree debris

• 188kg of dry woodblock

Covered with:

• 52 kg compost

• 14 kg soil

• 63 kg of red clay

• 23 kg of lump biochar

• 20kg animal manure

TEMPERATURE, OC, IN BIOCHAR BELOW COMPOST

• 565 after covering, 5pm

• 380 that night, 9pm

• 244 next morning, 9am

• 289 next night, 6pm

• Quenched with small amount of water

• Volume of char formed when kiln is full = 800 L

• Mass of dry char1 = 160 kg

• Mass of dry feedstock2 = 1000 kg

• Mass of water in feedstock3 = 176 kg

• Energy in original wood4 = 18,000 MJ

• Energy in char5 = 4,800 MJ

• Energy in syngas by difference = 13,200 MJ (73% of original wood energy)

• Power output of burning syngas over 5 hours = 2,640 MJ/h = 0.73 MW (averaged)

• Energy to dry wood and heat from 20oC to 280oC =4576,7+5208 = 987 MJ = 7.5% of Syngas

• Net energy in Syngas above kiln = 10,890 MJ (assuming also 10% thermal loss in kiln)

• Heat stored in char above 70oC8 = 77 MJ (160 kg @ average temperature of 550oC)

Water heating potential:

• Energy to heat water from 20oC to 70oC6 = 210 kJ/kg

• Hot water output from syngas combustion = 10,000 L @ heat use efficiency of 20%

Quench water:

• Water needed to quench char from 550oC to 70oC assuming no evaporation6 = 367 L of 20oC water

• Water needed to quench char from 550oC to 70oC assuming all evaporated6,7 = 31 L of 20oC water

ASSUMPTIONS 1. Bulk density of dry char = 0.20 kg/L 2. Char yield on dry basis = 16% db 3. Water content of wood = 15% wb 4. Heating value of wood = 18 MJ/kg 5. Heating value of char = 30 MJ/kg 6. Specific heat water = 4.2 kJ/kgoC 7. Water vaporization = 2260 kJ/kg 8. Heat capacity of wood = 2 kJ/KgoC 9. Heat capacity of char = 1 kJ/KgoC

Mass-Energy Balance of Kon-Tiki 1.5m