Post on 17-Jan-2016
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State of the Art in Rice Husk Cook Stoves
Marc ParéMechanical Engineering // Georgia Tech
Jan 2011 // ETHOS Conference
Saturday, January 29, 2011
Saturday, January 29, 2011
[Resource Opportunity]
[Properties of Rice Husk]
100 kW($4000)
0.8 kW($30) 0.3 kW
($20)0.3 kW($10)
[Resulting Notable Designs]
Saturday, January 29, 2011
World Rice Consumption 2008 (USDA)Saturday, January 29, 2011
Saturday, January 29, 2011
432,039 metric tons of rice consumed / year
x 12 GJ / metric ton
/ 1.3 MJ to cook a meal
2 billion meals / year
x 0.6 milling rate
How much energy is out there?
Saturday, January 29, 2011
Properties of Rice Husk
• Energy Content
• Chemical Composition
• Angle of Repose
• Thermal Conductivity
• Air Flow Resistance
Saturday, January 29, 2011
Properties of Rice Husk
• Energy Content
• Chemical Composition
• Angle of Repose
• Thermal Conductivity
• Air Flow Resistance
or Understanding a Really Strange Fuel
Low
High in Silicates
Causes Bridging
Can Put Out Fires
Darn High
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Energy Content
Hull
Char
Ash
3000 kcal / kg
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Saturday, January 29, 2011
Losses9%
MgO2%
Al2O36%
CaO2%
Fe2O31%
SiO280%
Ash Chemical Composition
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Angle of Repose
θ
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Thermal Conductivity
Test Results from ASTM testing by R&D Services of Cookville, Tennessee (Courtesy Dr. Paul Olivier)
Saturday, January 29, 2011
Dr. Paul Olivier http://www.esrla.com/Saturday, January 29, 2011
Resistance to Air Flow
• Pressure drop higher than that generated by stack effect in a natural draft cook stove
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“The high percentage of silica in rice hulls and the peculiar silica-cellulose structure impede uniform and thorough burning of the hulls in a combustion process.”
“Eldon Beagle set a pile of rice hulls 300’x500’x50’ on fire and they burned for six months.”
“However, husk cannot be burnt easily or cleanly with excess air, and energy recovery is very low as the heat produced cannot be utilized in a beneficial manner.”
Beagle (1978), p. 8. , Velupillai (1996), p. 18., Ibid., p. 24. , Ibid., p. 25.
Summary, courtesy of Eldon Beagle
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It can’t be done?
Saturday, January 29, 2011
Gasification
• Two-stage
• Cleaner burn
• More fuels
• Air-controlled
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Power Generation
$34 / kW30-300 kW
• Fluidised bed
• Projects around the world
Dr. Alexis Belonio
Saturday, January 29, 2011
Forced Air Batch Gasification
$1130.8 kW• Requires a fan and
electricity
• Blue flame
• Easy to control
• Batch operation
Dr. Alexis Belonio
Saturday, January 29, 2011
Dr. Paul OliverSaturday, January 29, 2011
Saturday, January 29, 2011
Continuous Quasi-Gasification
$300.3 kW• Requires tapping every
few minutes
• Continuous operation
• Easy to start
• Emissions?
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Saturday, January 29, 2011
Natural Draft Batch Gasification
$200.3 kW
• Chimney provides necessary draft
• Very little material
• Batch operation
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Saturday, January 29, 2011
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• TEG (or thermopile) to power fan
• More autonomous continuous stove
• Blue flame on natural draft stove
• More options for cooking surface construction
Future?
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smallredtile.com
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Sources• IRRI World Rice Statistics http://beta.irri.org/solutions/index.php?
option=com_content&task=view&id=250
• Chemical Analysis of Rice Husk Ash: http://www.scribd.com/doc/3085035/Chemical-Analysis-of-Rice-Husk-Ash
• Rice and Straw Properties (Rice Knowledge Bank) http://www.knowledgebank.irri.org/rkb/index.php/rice-milling/contributions-and-references-milling/further-information-byproducts/husk-and-straw-properties
• “No other plant offal even approaches the amount of silica found in rice husks.” Beagle, E.C. 1978. FOA Agricultural Services Bulletin 31, p. 8.
• Kaupp, A. (1984). Gasification of Rice Hull: Theory and Praxix. Federal Republic of Germany: GATE/GTZ. 303pp.
• http://gasifiers.bioenergylists.org/content/continuous-flow-rice-husk-gasifier-thermal-application
• Sawdust stove image: http://www.motherearthnews.com/Do-It-Yourself/1974-11-01/How-To-Sawdust-Stove.aspx
•
Saturday, January 29, 2011