Rice Husk Cook Stoves

State of the Art in Rice Husk Cook Stoves

Marc ParéMechanical Engineering // Georgia Tech

Jan 2011 // ETHOS Conference

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]


World Rice Consumption 2008 (USDA)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?


Properties of Rice Husk

• Energy Content

• Chemical Composition

• Angle of Repose

• Thermal Conductivity

• Air Flow Resistance


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


Energy Content

Hull

Char

Ash

3000 kcal / kg



Losses9%

MgO2%

Al2O36%

CaO2%

Fe2O31%

SiO280%

Ash Chemical Composition


Angle of Repose

θ


Thermal Conductivity

Test Results from ASTM testing by R&D Services of Cookville, Tennessee (Courtesy Dr. Paul Olivier)


Dr. Paul Olivier http://www.esrla.com/Saturday, January 29, 2011

http://www.esrla.com

http://www.esrla.com

Resistance to Air Flow

• Pressure drop higher than that generated by stack effect in a natural draft cook stove


“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


It can’t be done?


Gasification

• Two-stage

• Cleaner burn

• More fuels

• Air-controlled


Power Generation

$34 / kW30-300 kW

• Fluidised bed

• Projects around the world

Dr. Alexis Belonio


Forced Air Batch Gasification

$1130.8 kW• Requires a fan and

electricity

• Blue flame

• Easy to control

• Batch operation

Dr. Alexis Belonio


Dr. Paul OliverSaturday, January 29, 2011


Continuous Quasi-Gasification

$300.3 kW• Requires tapping every

few minutes

• Continuous operation

• Easy to start

• Emissions?



Natural Draft Batch Gasification

$200.3 kW

• Chimney provides necessary draft

• Very little material

• Batch operation




• TEG (or thermopile) to power fan

• More autonomous continuous stove

• Blue flame on natural draft stove

• More options for cooking surface construction

Future?


smallredtile.com


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

•


http://beta.irri.org/solutions/index.php?option=com_content&task=view&id=250




http://www.scribd.com/doc/3085035/Chemical-Analysis-of-Rice-Husk-Ash




http://www.knowledgebank.irri.org/rkb/index.php/rice-milling/contributions-and-references-milling/further-information-byproducts/husk-and-straw-properties






http://gasifiers.bioenergylists.org/content/continuous-flow-rice-husk-gasifier-thermal-applications






Documents

Rice Husk Cook Stoves