HOUSEHOLD-SIZE CONTINUOUS-FLOW RICE HUSK GAS STOVE

by: Alexis T. Belonio, Emmanuel V. Sicat, and Francisco D. Cuaresma
Again, good news and glory to God!
The rice husk gas stove technology which
was recently developed for domestic
application now operates on a continuous
mode. Instead of discharging char and
reloading fuel every 40 minutes to continue
its operation, the rice husk gas stove can
now be operated continuously until all
cooking jobs is finished. Rural households
can now cook more conveniently using this
stove model than with the batch-mode
model.
This development in the rice husk stove
technology was realized with the funding
support from the Rolex Awards for
Enterprise 2008 and The Tech Awards
2010.  The stove, as shown in the upper
right photo, is a modified version of the
single-burner rice husk gas stove. As
shown, this stove model has feeding hopper
and a discharge mechanism in one reactor
to allow continuous feeding of rice husks
and discharging of char during operation.
Similarly, the stove consists of the reactor
where rice husks are burned with limited
amount of air producing combustible gases
that are rich in carbon monoxide (CO) and
hydrogen (H
2
). Rice husks are fed onto the
hopper which is positioned directly above
the reactor, and char is discharged into the
pan placed directly beneath the reactor.
The gas generated during the process is
diverted through a duct to the other
cylinder with the gas burner mounted on it.
After cooking, the char is collected using a
Stove Design and Performance Specification
pan for proper disposal.
The proto-type model of the stove
has a reactor diameter of 12 cm and
a height of 30 cm. A 3-watt, 12-volt
DC fan supplies the air needed in
gasifying rice husks.  The fan can be
energized by plugging it into a 220-volt AC convenience outlet with the
use of an AC-DC Adoptor, a 12-volt
DC battery, or at least 1.5 watt with
the same voltage solar panel. The
average amount of rice husks
consumed per hour of operating the
stove is 1.1 kilogram with a computed
thermal output of 1.19 kWt.
The intensity of flame can be varied by
shifting the Adoptor switch from 1.5 to 12
volt or by changing the opening of the fan
inlet.  The time required to produce gas
from the time of ignition of fuel is 2
minutes.  Two liters of water can be boiled
using the stove within 14 minutes with a
thermal efficiency of about 21%. Specific
gasification  rate was computed at 96 kg per
hour-m
2
. The temperature measured
beneath the pot during boiling test varies from 250 to 400°C. The expected black carbon
emission is no more than 100 ug/m
3
of gas, which is almost the same with that of the batch-type
rice husk gas stove.
A unit of this stove costs P2,000.00-2,500.00 depending on the kind of materials and the method
of manufacturing used.  This selling price is almost the same with that of the commercial units of
the batch-type rice husk gas stove being produced.  Investment can be recovered within 3 to 4
months as compared with LPG stoves.
For further information, please send email to atbelonio@yahoo.com or write to Center for Rice Husk Energy
Technology, College of Engineering, Central Luzon State University, Science City of Munoz, Nueva Ecija,
Philippines.
Release: March 23, 2011