DESIGN AND PERFORMANCE OF A HOUSEHOLD-SIZE CONTINUOUSFLOW RICE HUSK GAS STOVE

The cost of fuel for domestic cooking is  now at the range of
P55 to P70 per kg. Conventional cooking stoves, such as gas
and liquid burners, are convenient to use and to operate but
now prohibitive. Due to this, households  particularly in  the
villages  adopt  biomass  and  wood  as  fuel  for  their  cooking
needs.   This  practice  is  affordable,  but  produces  excessive
smoke  and  particulate  emissions.  It  was  reported  by  the
World  Health  Organization  (2005)  that  indoor  pollution
caused  by  too  much  smoke  emission  in  the  traditional
burning  of  wood  and  biomass  stoves  resulted  in  about  1.6
million  deaths  per  year  in  developing  countries  due  to
chronic respiratory diseases.
Rice  husk, a by-product in  rice  milling is  abundant.  In the
past,  it  is  disposed  by  burning  along  road  sides  and/or  by
dumping on river banks. About 2 million metric  tons of rice
husks is produced  annually with enough potential energy as
fuel for domestic household (Belonio, 2005). A  kilogram of
rice  husk,  contain  about 3,000 kcal of heat  (Kaupp, 1984).
Despite of the varied applications or usage of rice husks, the
abundance in supply of this waste material can still warrant
as an alternative source of energy for the rural people.
Gasifying  rice  husks  is  a  good  alternative  to  provide
households  with  low-cost  but  clean  source  of  energy  for
cooking  (Anderson,  et  al,  2006  &  Anderson,  et  al,  2008).
By  limiting  the  amount  of  air  used  in  burning  rice  husks,
combustible gas that is rich in carbon dioxide and hydrogen
are produced  (Belonio, 2005). Several studies revealed  that
a stove that operates on gasification has low particulates as
well as  CO2
emission  (Anderson, et al, 2006, Anderson, et
al,  2008  &  Teenet,  Undated).   Among  the  various  gasifier
stoves  tested  on  spot  during  the  US-ASEAN  NewGeneration  Stove  Workshop  at  Asian  Institute  Technology
in  Thailand,  the  rice  husk  gas  stove  obtained  the  lowest
black  carbon  emission  of  about  50ug/m
3
of  gas  (Hansen,
2009).
In  2005,  a  batch  type,  top-lit  downdraft  type  rice  husk
gasifer stove was developed at Central Philippine University
in  Iloilo  City  (Belonio,  2005).  The  stove  has  caused  the
widespread acceptance of the technology by the people not
only in the Philippines but also in other rice producing areas
in  the  world  like  Indonesia,  Vietnam,  India,  and  other
countries  in  Asia,  Africa  as  well  as  Central  and  South
America  (Belonio, 2009 & Minang, et al 2007).  However,
because of the differences in cooking practices and needs by
households,  a  rice  husk  gas  stove  that  operates  in  a
continuous mode was designed and developed.
This  paper  describes  the  design  and  performance  of  a
household-size continuous-flow rice husk gas stove aimed to
provide  households  a  simple  and  clean  burning  stove  for
cooking.   The  comparative  operating  cost  analysis  against
LPG and kerosene burners is also presented in this paper

2.1  Design Preparation

The  design  of  the  stove  was  based  on  the  principle  of
bottom-lit  moving-bed  down-draft  type  rice  husk  gasifier,
which  was  recently  developed  for  industry  application
(Belonio,  et  al,  2010).   Instead  of  multiple  locations
provided  for  fuel  ignition,  only  one  ignition  point  was
considered in the present design. The size of the reactor was
scaled down to nearly 1 kWt, just enough for a family with 3
to  4  members.   The  amount  of  air  needed  to  gasify  rice
husks was computed using an equivalence ratio of 0.3 to 0.4
with stoichiometric air for rice husk of 4.7 kg air per kg of
fuel as recommended by Dr. Albreacht Kaupp (1984).
After  finalizing  the  conceptual  design  of  the  stove,  a  3D
AutoCAD  drawing  was  prepared  to  ensure  consistency
throughout the different assemblies. A 2D drawing was also
prepared  to  serve  as  a  guide  in  the  fabrication  of  the
different parts of the stove.
2.2  Fabrication
Prior to fabrication, the design drawing was discussed with
the Fabricator  to  simplify the construction of the stove  and
to make the unit durable and affordable.
The  stove  was  fabricated  at  BMC  in  Pavia,  Iloilo,
Philippines.   Further  revisions  and  improvement  of  the
design was done at BEST-Enterprise at the Science City of
Munoz, Nueva Ecija, Philippines. Regular shop visits were
made until construction of the stove was completed.

Performance Testing and Evaluation

The  final  proto-type  of  the  stove  was  tested  using  water
boiling tests. Series of tests were conducted at  BMC shop
as well as at CLSU-CRHET Rice Husk Project Office at the
College  of  Engineering,  CLSU.   During  testing,  fresh  rice
husks were used as fuel for the stove.  The time to ignite rice
husk  fuel and the time to generate  combustible gases  were
also taken in each test.  One liter and 2 liters of water were
boiled in the stove for more than an hour. In each test, the
time required to boil water was determined. During the test,
the temperature of water was measured at 2-minute interval
using  a  bimetallic  thermometer.   The  gas  temperatures  as
well  as  the  flame  temperatures  beneath  the  pot  were
recorded every 10 minutes using a digital thermometer with
type  K  thermocouple  wire  sensor.   The  amount  of  water
remaining  in  the  pot  was  also  measured  in  each  operation.
The following parameters were determined during the tests:
(1) Fuel consumption rate; (2) Specific gasification rate; (3)
Thermal  efficiency;  (4)  Power  output;  and  (5)  Percentage
char produced.

Operating Cost Analysis

The cost of operating the stove was determined based on the
investment  cost,  which  is  the  actual  selling  price  of  the
stove.  The  investment  cost  and  the  costs  incurred  for  the
rice  husk  fuel  and  electrical  consumptions  were  computed
on a daily and on hourly bases. A comparative cost analysis
was done and the savings derived in using the rice husk gas
stove  over  conventional  stoves  was  determined.   The  time
required  to  recover  the  investment  for  the  stove  was  also
computed.

Design Description of the Stove

The stove, as shown in Figure 1 below, is a continuous-flow
moving-bed  rice  husk  gasifier  operating  on  a  bottom-lit
down-draft mode. It consists of the following components,
namely: (1) Fuel Hopper; (2) Fan; (3) Fuel Reactor; (4) Gas
Duct; (5) Gas Burner; (6) Pot Support; (7) Support Legs; (8)
Char Pan; and (9) Push Rod. The fuel hopper holds the rice
husks  in  place  before  they  are  fed  into  the  reactor.   Rice
husks  are  gasified  in  the  reactor  by  burning  them  with
limited  amount  of  air  supplied  by  a  12-Volt,  0.12-Amp
computer fan.  The reactor is made of a 1.2  mm GI sheet
and has a diameter of 12 cm and a height of 30 cm. The gas
duct, where combustible gases are diverted into, is made of
10  cm  diameter  cylinder  made  slightly  higher  than  the
reactor and the  fuel hopper. On top of the  gas duct is the
plate-type gas burner having 40 pieces 4 mm diameter holes.
The  char  pan  and  the  push  rod  are  used  to  remove  char
during operation. The entire structure is supported by four
pieces of inclined legs.

Fabrication of Stove

The  stove  can  be  fabricated  in  a  small  shop  using  local
materials  and  labor.  Galvanized  iron  sheet  or  conduit  and
bars are used as  materials  for the stove. Four  units of the
stove can be produced from one standard size 1.2-m wide by
2.4-m long metal sheet. For these four units of stoves, two
pieces of round bars are needed for  the legs and handle as
well as  for the  pot holder. One person can build one stove
in one day.

Test Performance

Results of the performance tests and evaluation revealed that
the stove performs well as per design. As shown in Table  1
below, rice husk consumption of the stove is at a rate of 1.07
to 1.12 kg/hr, depending on the degree of char removal and
on  the  amount  of  air  supplied.   Ignition  of  rice  husks  is
achieved  after  a  minute  of  dropping  before  combustible
gases are generated at the burner. It was found out during
the  test,  switching  the  fan  to  12  volts  will  facilitate  the
ignition  of  rice  husks,  shorten  the  generation  time  of
combustible  gases,  and  minimizes  smoke  emission.  It  was
also  observed  that  the  use  of  dry  and  fresh  rice  husks
produces less smoke.
To  boil  a liter of water  in the stove takes 5 to 7.6 minutes,
depending on the intensity of the flame. The higher the fan
voltage  setting,  the  stronger  the  flame  produced;  hence,
shortening  the  boiling  time  of  water.   On  the  other  hand,
boiling  2  liters  of  water  requires  between  10.4  to  15
minutes. Figure  4  shows the temperature profile of boiling
water  in  the  stove.   Gas  temperature  taken  at  the  gas  duct
using a thermocouple wire sensor, varies from 90 to 100°C;
whereas,  the  temperature  measured  beneath  the  pot  varies
from  250  to  400°C.   The  specific  gasification  rate  of  the
stove  varies  from  90  to  102  kg/hr-m2.  Furthermore,  the
thermal efficiency  of the stove varies from 18 to 25%. This
value  is  still  acceptable  since  the  gas  burner  operates
without  a  heat  shield  or  a  skirt  in  keeping  the  heat
concentrated at the bottom of the pot. The char production
rate or the amount of burned rice husk produced varies from
0.32 to 0.34%. In addition, the computed thermal output of
the stove is at the range of 0.69 to 1.01 kWt.

Operating Cost, Savings, and Payback Period

Table  2  shows  the  operating  costs  of  using  the  RHG,
kerosene  and  LPG  stoves.  The  RHG  stove,  including  the
12-volt  fan  and  an  AC-DC  adoptor  costs  P2,000.00.   A
typical  household  with  3  to  4  members  will  require  an
average  of  one  kilogram  of  rice  husks  per  hour  cooking.
The cost of electricity in operating the stove is very minimal
since the fan consumes only about 0.005 kw-hr. \
The computed fixed cost for the stove is P4.49 per day while
the variable costs, which are the costs incurred for the rice
husk fuel plus the small amount of electricity consumed in
running  the  fan,  is  P2.40  per  hr.     Considering  a  3 -hour
operation per day, the computed operating cost per hour for
the stove is only P2.30. Comparing the rice husk gas stove
with  conventional  stoves,  consumption  of  kerosene  is
assumed at 0.25 liter per hour while for LPG is 0.15 kg per
hour. Investment cost for the kerosene stove is cheaper than
that of LPG stove, which is slightly higher than that of the
rice  husk  gas  stove  due  to  the  cost  of  tank,  hose,  and
regulator. The  computed fixed costs for kerosene and LPG
stoves are P0.79 and P5.69 per day, respectively. The cost
of fuel used per hour is quite expensive for the conventional
stoves giving P37.50 and P31.50 for kerosene and LPG fuel,
respectively.   The  cost  to  operate  the  kerosene  stove  per
hour  is  computed  at  P12.76   while  P12.40  for  LPG.   The
households who will opt to use the rice husk gas stove can
have  a  daily  savings  of  P10.46  over  the  use  of  kerosene
stove and P10.10 over the use of LPG stove. For the period
of one  year, a total savings of P11,457.35 can be derived by
households  over  the  use  of  kerosene  stove  and  P11,059.50
over the use of LPG. The investment for the rice husk gas
stove can be recovered with 2 to 3 months.

 CONCLUSIONS AND RECOMMENDATIONS

Based  on  the  results  of  the  study,  the  rice  husk  gas  stove
performs accordingly  with  the  design.  It can  satisfactorily
provide  combustible  gases  for  continuous  operation  for
more  than  one  hour  of  domestic  cooking.   It  can  be
energized  either  by  direct  connection  into  an  AC-DC
calculator adoptor in areas where grid is available or by the
use of a 12-volt battery with 12-  volt 5-watt solar panel in
off-grid situation.  With proper operation, smoke  is almost
completely  eliminated  and  clean  combustible  gases  for
cooking is achieved. The stove can be fabricated even in a
backyard shop using metal sheets and  steel  bars employing
the  local  people.   The  price  of  the  stove  is  affordable  to
many and households can generate substantial savings from
the  use  of  biomass  fuel  over  the  use  of  conventional  fuel.
Investment  can  be  recovered  within  a  short  period  of  less
than a year.It is likewise recommended that further improvement on the
rice husk gas stove must be done to cater the specific needs
of  households  in  terms  of  comfort  and  convenience   in
cooking operation.

SMALL-SCALE RICE HUSK GASIFIER PLANT FOR COMMUNITY STREET LIGHTING

by
Alexis Belonio, Victoriano Ocon, and Antonio Co
Garbage-In Fuel-Out (GIFO) Project
Suki Trading Corporation, Lapu-Lapu City, Cebu, Philippines
Glory to God!
A rice husk gasifier plant, enough to provide
electricity for community street lighting, was
recently developed by Suki Trading
Corporation in Lapu-Lapu City, Cebu,
Philippines in collaboration with Kanvar
Enterprises and the Center for Rice Husk
Energy Technology (CRHET).
The project aimed at using wastes from rice
mills to fuel a spark-ignition engine that will
drive a generator to produce electricity.
Instead of dumping rice husks along roadsides,
it can now be converted into valuable fuel that
can help communities energize their street
lights.
The gasifier basically employs a moving-bed
downdraft gasifier reactor developed by
CRHET in combination with a gasconditioning devices that remove impurities
from the gas thereby making it highly suitable
fuel for heat engines.
As shown, the gasifier is a small unit with 40-cm diameter reactor equipped with 3-in., 220-volt electric blower to provide the air needed in
gasifying rice husks to produce carbon
monoxide (CO) and hydrogen (H2
) gases.
Rice husk is fed at the top end of the reactor
either manually using a ladder or with the use
of a bucket elevator.
Rice Husk Disposal Practice
Pictorial of the Power Generating Plant
On the other hand, char
is removed from
beneath the char box
using a screw conveyor.
The gas coming out of
the reactor is
conditioned by allowing
it to pass through the
gas-cleaning devices
which consisted of wet
scrubbers, tar
condenser, and a series
of packed and bag
filters.
The gas is fueled to a 3-cylinder, 12-valve
surplus Susuki engine which directly drive a 10-kWe AC synchronous generator at a speed of
1,800 rpm producing 220 volt current.
A total of 160 pieces of 50-watt bulbs can be energized by the plant for 8 to 10 hours continuous
operation. The plant consumes rice husks at an average rate of 19 kg per hour.
The gas temperature coming out of the reactor ranges  from  400 to 550°C.  It dropped between 50
to 70°C after passing the wet scrubbers, and
further cooled down between 35 to 42°C before
entering the intake manifold of the engine.
Gas flow rate is at 24 Nm
3
per hour.
The engine is entirely fueled by the gas
generated, except at the start-up and at the end of
the operation.  Furthermore, a parasitic load of
15% of the power output is needed to run the
plant itself.
One trained person is required to operate the
plant, to load the fuel and discharge the char and
at the same time to oversee the operation of the
plant.
The gasifier produces a clean gas with a very
low amount of black carbon (i.e., only 50 um/m
3
of gas), and so the gas coming out of the muffler
of an engine is also clean.  CO2 emission is
Operation of the Gasifier
likewise relatively low of about 0.6 kg per ton of rice husks.
The char produced is about 30 to 35% of the rice husks consumed. Char  is a good material in
increasing the water holding capacity of the soil.
The advantage features of the gasifier system are:
(1)  It makes use of available wastes  in rural areas to fuel engines that usually drive
generators;
(2)  The tar problem which is common among conventional rice husk gasifier systems  is
eliminated  in this gasifier technology;
(3) Operation can be done continuously without the need  to restart the reactor;
(4) It can easily be adopted with surplus spark-ignition engine that is readily available in
the locality;
(5) The technology can be locally produced making use of available fabrication resources
and skills;
(6) It can be scaled up to meet the power demand of a certain community or application;
and
(7) Investment and operation cost s are at the reach of  the local community.
The entire plant requires an investment cost of P420,000.00, excluding shipment. With proper
operation and maintenance, it can last even for a minimum period of 5 years. It can be recovered
within a year when operated at 8 hours per day, and 365 days per year.
Development of a large-scale unit of the gasifier plant, aimed at utilizing city garbage so as to
avoid trashslide,  is now underway.
This development platform of GIFO Project is geared towards helping communities or local
government units eliminate the problem of garbage disposal while, at the same time, providing a
solution to both energy and environmental problems.
For further information, please contact: Suki Trading Corporation, Lapu-Lapu City, Cebu,
Philippines at sukitradingcenter@yahoo.com  or Engr. Alexis Belonio at atbelonio@yahoo.com.
Released: September 9, 2011
Sources:
http://www.bioenergylists.org/en/node/3066http://www.bioenergylists.org/en/node/3066
http://nexus-scu.org/energymap/wp-content/uploads/2011/10/Small-Scale-RHGP-10-KVA-for-StreetLighting-1.pdf

RICE HUSK GAS BURNER FOR BAKERY OVEN

Engr. Alexis Belonio
Central Philippine University
Iloilo City, Philippines
Good news to bakers! Instead of spending
hundreds of pesos for LPG, you will now only
spend less for your baking!
A rice husk gas burner for bakery oven is now
commercially available. This rice-husk-fuelled
gas burner significantly reduces the cost of fuel
for baking. In this technology, rice husk is
gasified inside the reactorand the gasgenerated
is ignited at the burner, which produces
luminous bluish flame for heating bakery oven.
The gas burner can be conveniently operated as
compared with other rice-husk-fuelled ovens.
The amount of flame can be uniformly
controlled with the use of a switch.
The Fuel Reactor Assembly
The rice husk gas burner for bakery
ovens is another breakthrough in the
area of rice husk gasification, which
is carried out by the Department of
Agricultural Engineering and
Environmental Management of the
College of Agriculture, Central
Philippine University in Iloilo City,
Philippines. This technology was
developed with the assistance from
the group of undergraduate
agricultural engineering students
Lucio Larano, Daniel Belonio, Yvone
Herbo, and Jeffrey Cocjin.
The Two-12 plate Oven Fired by the Rice
Husk Gas Burner
The rice husk gas burner for bakery
ovens consists of the following
components: (1) Dual Fuel Reactors
- where rice husks are gasified during
operation by burning them with
limited amount of air; (2) Char
Chamber – where burnt fuel is
discharged fromthe reactor after
gasification; (3) Blower – which
supplies the needed amount of air for
gasification; (4) Char Lever – which
discharges burnt rice husk after
gasification; (5) Control Switch –
which intensifies or lowers the
flame; (6) Gas Pipe – which conveys the gas generated fromthe reactor to the burner; (7)
Chimney – which discharges unwanted gases; and (8) Gas Burner - where the gas is
burned.
The Burning Gas Insidethe Oven
The fuel reactors havea diameter of
25 cmand a height of 1 meter. They
are located outside the baking room
for ease of operation. The burners are
extended fromthe reactor to the oven
through a pipeline. Operation is
being done by dual mode so that
continuous firing in the oven can be
achieved.
Flammable gases, primarily of
carbon monoxide and hydrogen, are
produced during operation as the
burning fuel moves down the reactor.
The by-product after gasification is
carbonized rice husk, which is a
good material for composting.
During Baking Operation
The rice husk gas burner supplies
energy to two 12-plate ovens
simultaneously. One or two minutes
is required to start firingthe rice
husks in the reactor. Once the rice
husk are ignited, continuous
operation is achieved for 30 to 40
minutes before shifting to the other
reactor.
Mr. Gil Cordon Owner of the Bakery Shop
The rice husk gas burner featured in this article is owned by Mr. Gil Cordon, a baker
from Jaro, Iloilo City. According to him, heuses LPG fuel for 10 minutes to start-up the
oven and after that shifts to the rice husk gas burner until operation is done. He also uses
LPG fuel as back up in case of power failure. Both ovens are simultaneously used when
baking “Pande leche,” “Pande sal,” and other similar bread. When baking “Mamon” and
“Hopia” either one or two ovensLPG back-up is used.
Cost analysis showed that for an investment of P30,000.00 for the rice husk gas burner,
the cost of operation is only P16.59 per hour. This amount is significantly lower as
compared when using the LPG burner, which is P41.67 per hour. With a difference of
P25.08 per hour in operating cost, a yearly savings of P115,562.65 can be realized when
using the rice husk gas burner instead ofthe LPG burner. The payback period was
computed at 0.25 year, equivalent to 3 months. The return on investment is 385.21% and
the benefit cost ratio is 1.51.
The technology is now in commercialization stage. Interested individuals or
organizations who wish to order this baking technology may contact the Project Director,
Appropriate Technology Center, Department of Agricultural Engineering and
Environmental Management, College of Agriculture, Central Philippine University, Iloilo
City, Philippines. Telephone number 063-33-3291971 loc 1071, email ad
atbelonio@yahoo.com, and mobile phone 063-0916-7115222.
1 USD = 50 PHP

A 3-KW RICE-HUSK MICRO GASIFIER POWER-GENERATING DEVICE DEVELOPED FOR INDIVIDUAL FARMER’S USE

by
Alexis T. Belonio, Emmanuel V. Sicat, Marlon T. Delos Santos, and Elmer D. Castillo
Good news and
Glory to God!!
Amid problem on
high fuel cost, a
practical solution is
at hand. Farmers
now have an
alternative in
generating
electricity for their
home use with the
latest development
on rice husk
gasification
technology to run
small-gasoline
engine that can
drive a 3-kW
generator. This
rice-husk micro
gasifier power-generating device is one of the
developmental activities of the Center for Rice Husk
Energy Technology –Central Luzon State University
(CRHET-CLSU) Rice Husk Project purposely to come
up with a simple technology that utilizes rice husks,
which are the by-product from milling rice and can
augment farmers’ income thus improving their living
condition. With this technology, farmers can now
utilize their rice husks to provide power for their
home energy need such as lighting, radio and TV,
charging cell phones, cooking with electric stove,
and even to supply electricity for their domestic
water pumping need as well as for irrigating their
crops.  With the introduction of this latest
development on rice husk gasification technology,
agro-wastes produced in the farms can now be
turned to a useful energy source in meeting  the
need of farmers for electricity while, at the same
time, making the environment free from pollution.
This 3-kWe rice-husk micro gasifier power-generating device is a
small version of the continuous-type rice husk gasifier, with gas
conditioning units, producing clean gas that is used as fuel for
conventional spark-ignition gasoline engines. As shown in the
drawing above, this device consists of the following major
components: (1)  Gasifier reactor used to convert rice husks, by
burning them with limited amount of air, into combustible gases
rich in carbon monoxide (CO), hydrogen (H2), and methane (CH4);
(2) Wet scrubber used to remove particulates and tars by spraying
the gas generated with water; (3) Tar condenser used to turn
moisture from gas into liquid form; (4) Packed-bed and cloth filters
used to mechanically screen the gas in order to further separate
tar from water; and (5) Engine used to produce mechanical power
to drive a generator. All these components are joined together in
series to completely clean the gas as well as to reduce its
temperature.
The gasifier reactor has a 20-cm
diameter equipped with a 2-in.
electric blower to push the gas into
the bed of rice husks. The wet
scrubber has a spray tower made of
a 4-in. diameter by 60-cm high GI
pipe, which sprays water into the gas
at a rate of 2.1m
3
/hr. The tar
condenser has a 40-cm diameter and
a 120-cm height. It has also a 20-cm
diameter hole at the middle to
provide natural cooling of gas at the
condenser.  Moreover, the packedbed filter has a 40-cm diameter and
a 60-cm height.  It uses ½-in.
diameter by 45-cm thick bed
crushed-stones as filter.  It has also a
filter bag made of a 25 cm  x 60 cm
long cloth to further screen the gas
before injecting it into the intake
manifold of the engine.   A 13-hp,
single-cylinder, spark-ignition Kenbo
Engine is used to convert the gas into mechanical power. A 3-kW, 220-volt, single-phase, asynchronuous
generator is used to produce electricity.
The gasifier consumes rice husks at a rate of 6-7 kg/hr producing a 2.9 kW electricity, with 0.9kW
parasitic load. The gas leaving the reactor has an average temperature of 180–260C and subsequently
drops to 30-35C after passing through the wet scrubber, tar condenser, and filters.  The engine
requires 12-15 min to start up with gasoline.  Once the engine has started, it is then run with the gas
generated from the system. Towards the end of the operation, however, the engine is run again with
gasoline for 10 minutes before shut off to clean the engine combustion chamber from tar.  No
modification is done on the engine, except for the provision of an intake port that by-pass the
carburetor. Operation of the plant is simple and can be easily understood by farmers who have the
experience in operating engines.
This power-generating device,
including the gasifier, the gas
conditioning units, the engine and
the generator, requires an initial
investment of around P55,000.00. If
farmers will save his rice husks and
use it as fuel, he can generate power
for his house and farm uses at less
than P3.36 per kw-hr. Comparing
this with the prevailing cost of
electricity of P10.50 per kw-hr, a
daily saving of P85.79 to 209.73 can
be derived.  The investment for the
entire system can be recovered
within 0.72 to 1.76 years depending on the utilization.
Aside from the saving that can be derived by farmers, this technology can benefit the farmers
themselves, the community and the country, in general, in terms of the use of a clean energy,
generation of employment for local people, availability of electricity for the farms especially in remote
areas which can impel micro business enterprises, increase in revenue for the locality, and improve
quality of life of the people in rural areas.
For more detailed information, kindly contact:
Engr. Alexis T. Belonio
Project Director, CRHET-CLSU Rice Husk Project
College of Engineering, Central Luzon State University
Science City of Munoz, Nueva Ecija, Philippines
Email: atbelonio@yahoo.com
We wish to thank Pauchon Foundation of Morgan Hills, California, USA; and the 6m’s Ag Biosystem
Engineering Enterprise and Consultancy Corporation, Philippines for providing the funds in developing
this power-generating device. The Super Trade Enterprise,Philippines for the allowing us to use their 13
hp KENBO Engine for the testing and evaluation of the gasfier as well as the Agricultural Engineering
Students of CLSU (Genesis Lazo, Roel Pranilla, and Rafael Domingo) who helped in testing and evaluating
the device.
May this technology help our farmers especially those who don’t have access to the grid!
Released: March 2012

A 5-KWE RICE HUSK GASIFIER POWER GENERATING PLANT

by
Alexis Belonio
Glory to God!!
A 5-kWe rice husk gasifier
power generating plant was
recently developed to provide
out-of-the-grid areas of a local
technology for generating
electricity using rice husks as
fuel.  By gasifying rice husks, a
clean fuel is produced which
can be used as replacement for
the conventional gasoline fuel
for a spark-ignition engine that
drives a generator to produce
electricity.  This technology is
another development by the
Center for Rice Husk Energy
Technology, in collaboration
with private entrepreneurs,
aimed to provide the rural
sector an appropriate
technology for generating
electricity using agricultural
wastes as fuel.
As shown at the right, the gasifier
generally consists of:  a reactor where
rice husks are converted to
combustible gas rich in carbon
monoxide, hydrogen, and a very little
of methane; a wet scrubber where the
gas, after leaving the reactor, is washed
by spraying with water; a packed-bed
filter which mechanically screens the
gas leaving the wet scrubber; and an
engine-generator set which produces
electricity using the gas generated.
Pictorial of the 5-kWe Rice Husk Gasifier
Power Generating Unit
The gasifier reactor is a moving-bed downdraft
type with 0.35-m diameter. The wet scrubber
is an impact-type with 10-cm diameter by 1.2-m high spray tower and a water tank made of
200-liter-capacity petrol drum. A 1/2-hp selfpriming pump is used to circulate the water
from the tower to the tank, and vice versa.  The
hot water is subsequently cooled in the pond
made of petrol drum which was cut into halves.
The packed-bed filter is also mad e of a petrol
drum with filter material made of 0.4-m thick
rice husks, wood chips, stone or anything that is
readily available in the farm.  After passing the
filter, the cleaned gas is directed to a 16- or 18 -hp gasoline engine to drive the 5-KW AC
synchronous generator.
Rice husks are manually fed into the gasifier reactor using a platform.  Char is discharged from
the bottom end of the reactor by swinging the lever and by rotating the scraper to eliminate
bridging. As rice husks burns
inside the reactor, the fire zone
moves upward producing
combustible gas which is
subsequently used as fuel for the
engine. The gas is cleaned and
cooled by allowing it to pass
through a series of washing and
filtering to remove particulates
and tars.  The water used in the
wet scrubber is cooled naturally in
a pond of water located next to
the scrubber. Accumulated
particulates and tars are allowed
to drip out of the tank and of the
pond from time to time. Water is
added or replaced in the cooling
pond when needed.  Filters are
backed-wash, when needed, to
clean.
The gasifier consumes 12 kg of rice husk per hour.  It requires 5 to 10 minutes from start-up to
produce combustible gases from the rice husk fuel.  The temperature of the gas leaving the
reactor ranges from 205° to 258°C. After passing the wet scrubber and the packed-bed filter,
The Gas Intake Port to the Engine
the gas temperature drops to around 38° to 43°C. The computed specific gasification rate of
the gasifier is 125 kg/hr-m
2
.   Water to gas ratio is 2.1 liters per m
3
of gas.  The total electrical
power produced is 4.9 kWe with parasitic load of 1.0 kWe.  Specific fuel consumption is 2.4
kg/hr-kWe.
The power generating device can provide electricity to remote places that are far from grid to
light group of houses, small community street lighting, and to energize  home-based industry.
Using this device, moreover, disposal of rice husks can be addressed and the problem on
greenhouse gas emission can be mitigated since gasifier, basically, has reduced CO2
and black
carbon emission during operation.
The gasifier power generating unit can be built locally using available local materials such as
petrol drums, steel bars, and metal sheets and plates.  Standard parts such as pump, blowers,
engine, and generator can be purchased from local suppliers.  Local skills can be utilized in
constructing the gasifer using commonly available tools and equipment.   Investment cost for
the plant, including the shed , is around P250,000.00. One person is needed to attend the
operation of the plant – i.e., to load fuel and to discharge char as well as to oversee the
operation of the different components of the power generating unit. Investment can be
recovered within a year, considering an 8-hour operation a day and the cost of rice husk of
P5.00 per bag, as compared when the engine driving the generator uses purely gasoline fuel.
For further information contact:
The Project Director (atbelonio@yahoo.com)
Center for Rice Husk Energy Technology
CLSU-CRHET Rice Husk Project
Room 201, PHILSCAT
College of Engineering, Central Luzon State University
Science City of Munoz, Nueva Ecija, Philippines
Acknowledgment:
CRHET acknowledges Pauchon Research Foundation of Morgan Hill California for the support in carrying out this
project to develop series of micro-gasifier power generating units to benefit the rural people, especially the
farmers. The Tech Awards 2010 and the Rolex Awards for Enterprise 2008 for the funding support in the early
development of rice husk gasifiers, particularly the moving-bed downdraft-type reactor.  To Edward Ligisan and
Charlie Buco of Biomass Energy System and Technology Enterprises (BEST-e) for fabricating the unit of the gasifier
as well as to Genesis Lazo and Roel Pranilla who assisted in the testing of the gasifier.
Updated:  January 2013

A RICE-HUSK-GAS-FED BAKERY OVEN DEVELOPED FOR SMALLCOTTAGE INDUSTRY USE

by
Alexis Belonio, Emmanuel Sicat, Catherine delos Reyes, Ireneo Agulto, and Francisco Cuaresma
Good news and glory to God!!
Baking in a conventional bakery oven
can now be done using producer gas
from rice husks.  Amid continued
increase in the prices of conventional
fossil fuel, small-cottage bakery
industry can still carry out their
business profitably using the newly
developed continuous-type rice-huskgas-fed oven. This technology is one of
the series of project developments
being done by CRHET-CLSU Rice Husk
Project under the College of
Engineering of Central Luzon State
University at Science City of Munoz,
Nueva Ecija, Philippines. The
Project aims to develop
technologies that utilizes rice
husks as source of fuel to help
small industries cope with the
high cost of fuel while, at the
same time, being
environment-conscious.
The oven, basically, is a boxtype structure commonly used
by Bakers in a small-cottage
industry business. It is made
of galvanized iron with 105-cm x 105-cm inside dimension
and a 50-cm height. The outside casing is made of the same material with a 1.2-m x 1.2-m
The Oven
total dimension and a 0.8-m
height. Inside the oven are
two layers of tray shelves
that can hold 4 to 5 pieces of
standard baking pan (33 cm
x 43 cm) per shelf.  A 2-in.
diameter pipe-type gas
burner indirectly heats the
oven at a temperature of
150C. The combustible gas
used for the oven is supplied
by a 0.3-m diameter
continuous-type rice husk
gasifier equipped with a 2-in.
350-watt, 220-volt electric blower.
Preheating of oven requires about 30 minutes to raise the temperature from 28 to 160C.
Once the temperature reaches 160C, trays of bread are loaded in the oven. A minimum oven
temperature of 140C is maintained throughout the baking period.  The breads are required to
stay inside the oven for 20 minutes.  During the first 10 minutes, trays of bread are loaded in
the lower shelf of the oven, and are subsequently transferred to the upper shelf  which are kept
for another 10 minutes.   The oven has a capacity of 8 to 10 trays per load.  Each tray can
accommodate 24 pieces of “Pandesal,” giving a total of 192 to 288 pieces per load.  In one hour,
it can bake a total of 768 to 960 pieces of
“pandesal.”  Moreover, the amount of
rice husks consumed is 7 to 8 sacks per
hour with an electrical consumption of
0.09 kW in one hour.  The temperature
at the burning zone of the oven, which
was taken directly from the top of the
flame, was measured from 220 to
405C. The gas temperature leaving the
reactor ranges from 172 to 180C.  One
person is needed to attend in the
operation of the oven.  The burning gas at the oven is generally light- blue with pink color and is
almost similar with that of the conventional LPG-gas fired oven.  Smoke emission is almost zero
when proper operation is observed. The char, which is the by-product from burning rice husks,
coming out of the gasifier is 25 to 30% of rice husks input.
Loading the Oven
The Burning Gas from Rice Husk
When operated for 8 hours, a minimum total of 6144
pieces of “Pandesal” for an 8-tray capacity  per day can
be baked. With the investment cost for the oven and
gasifier of P65,000.00, the computed baking cost using 8-tray loading capacity is P44.85 per hour or P 0.06 per
piece of “Pandesal.” Comparing with the current cost of
baking “Pandesal” using LPG of about P1.21 per piece
and considering an 8-hour per day and 20 days per
month operation, the investment for the oven and the
gasifier can be recovered within a period of one month.
Other advantage features of the oven and the gasifier
are:  (1) It is convenient to operate; (2) The gasifier
reactor can be put outside the baking room providing
clean environment during operation; (3) It can also be
operated using LPG, when needed; (4) It can be backedup with 12-volt, 100-amp-hour car or solar battery and
inverter, in case of brown out; (5) It can be built using
local skills and construction materials; and (6 ) the byproduct, which is the char, can be used in the rural areas
for improving the condition of the soil.
For more detailed information, please contact:
Engr. Alexis T. Belonio
Project Director, CRHET-CLSU Rice Husk Project
College of Engineering, Central Luzon State University
Science City of Munoz, Nueva Ecija, Philippines
Email: atbelonio@yahoo.com
We wish to thank ERDT for providing the fund for this project.  The following undergraduate
students of the Agricultural Engineering Department of CLSU College of Engineering, namely:
Genesis Lazo, Marlon delos Santos, Roel Pranilla, and Rafael Domingo who assisted in testing
and evaluating the gasifier oven.
Released: April 2012

Belonio 1991 Batch Type Rice Husk Gasifier Stove

A batch type rice hull gasifier stove was developed in April 1991 by Engr. Alexis Belonio under Central Philippine University in Iloilo for use by families in rural areas. The stove consists of a double-core down-draft type reactor were rice hull is gasifier, a burner were gas is burned to provide heat for cooking, a blower which is driven by a 95 W electric motor to suck the gas from the reactor and a chimney to divert undesirable gases during operation. The unit can be operated to provide heat for 1 hour operation. It can boil 1.5 liters of water within 10 - 34 mins and can cook 1 kg of rice in 16-22 mins. Performance evaluation showed that the stove have a gasification rate of 95 - 143 kg/m2-h and a thermal efficiency of 10%.  The stove can be locally fabricated at a cost of US$ 54 (P1,500.00). And can be operated at a cost of P0.98/h (about US$ 0.04/h)

Design specification and performance

Reactor:

• Inner core 
• diameter (cm)                          15
• length     (cm)                          65
• Outer core 
• diameter (cm)                          20
• length     (cm)                          70
• Grate type                                       Tilted
• Blower 
• Diameter (cm)               15
• Width (cm)                     5
• Power requirement (W)                    90       
• Burner type                                     LPG
• Operating time/batch                      1 hour 
• Gasification rate                            95 - 143 kg/m2-h
• Thermal efficiency                          10 %                 

A CLEAN BURNING COOKSTOVE DEVELOPED IN VIETNAM

by Alexis Belonio, Tran Binh, Doan Thi Minh Nguyet, and Bui Dinh Hai

Vietnam is producing a lot of biomass, such
as agricultural and forest residues, annually
amounting to about 7 to 8 and 75 to 100
million metric tons, respectively.  The
country’s pressing need for a low‐cost fuel
and a clean‐burning cook stove has led
VINASILIC to develop, in early 2009, a new
generation cooking technology that is
suitable for Vietnamese households.
Adopting the TLUD principle for the stove,
combined with the use of torrefied biomass
pellets as fuel for the stove, enable
VINASILIC to produce a biomass gas stove
that emits blue flame, shown in right photo,
with very low black carbon emission (less
than 50 ug/m
3
).
The stove, as shown in the above photo,
consists of a cylindrical reactor, an outer
cylinder, a gas burner, and a fan.  The
cylindrical reactor is where the fuel is
gasified.  It is provided
with grate at the bottom
for the passage of
primary air.  The outer
cylinder serves as stove
body and as burner
support.  The gas burner
is where the gas
generated from the
reactor, mixed with
preheated air, is ignited.
The fan is attached to
the stove body and is
used to supply the air
needed for gasification.
The stove is made of a
metal sheet, an earthen
ware and an ash
insulation to prevent
escape of heat through
the surface of the stove
body.  The primary air
enters from the bottom
end of the reactor with
the use of a 0.15‐Amp, 12‐
V DC fan.  The secondary
air, on the other hand,
enters the reactor through
the holes in the middle of
the stove body and is
mixed with the gas
generated at the small
holes located at the upper
portion of the burner.  A
skirt is sometimes
provided for the stove to
increase heat transfer
efficiency to the cooking
pot.
The stove comes in different sizes, as shown in Table 1 below.  Sizes 1 and 2 are for cooking
soup.   Sizes 3 to 5 are the standard cooking stove; whereas, size 6 is for cooking noodles.
As shown, the reactor diameter varies from 11.5 to 21.0 cm and the height varies from 9 to
36 cm.  The stove reactor can accommodate 0.17 kg of fuel for the smallest unit while 3.15
kg for the biggest.  The fuel can be ignited to produce combustible gases within 3 to 8
minutes, depending on the size of the stove.  Operating time is quite longer of about 50 to
75 minutes for the small stove while 180 to 240 minutes for the big stove.  Thermal
efficiency varies from 26 to 30%.  The computed power output ranges from 0.25 kW for the
small stove and 2.0 kW for the big stove.   On the average, the stove takes less than 5
minutes to boil a liter of water.  Other test results also show that one kilogram of rice husk
pellets can boil 18 liters within  45 minutes.  The temperature of the flame, measured using
infrared thermometer, varies from 280 to 350°C.
Table 1.  Design and Performance  of the Stove.
Size  Reactor
Diameter
(cm)
Reactor
Height
(cm)
Fuel
Capacity
(kg)
Start Up
Time
(min)
Operating
Time
(min)
Thermal
Efficiency
(%)
Power
Output
(kW)
1  11.5  9.0  0.17  3  50‐75  26  0.25
2  12.0  20.0  0.30  4  60‐90  26  0.35
3  12.0  20.0  0.47  4  75‐90  28  0.60
4  14.0  24.0  0.8  5  90‐120  30  0.90
5  16.0  30.0  1.5  5  120‐180  30  1.25
6  21.0  36.0  3.15  8  180‐240  30  2.00

The advantage features of the stove are: (a) No
smoke during operation, (b) No toxic gases are
emitted from the burning flame, (c) Easy to ignite
fuel, (d) Convenient to use and cooks food faster,
(e) Easy to adjust cooking to the user’s
requirements, (f) High efficiency, which save
much  fuel, and (g) Low investment cost.
The stove uses torrefied biomass from
agricultural and forest wastes, together with
coal.  The fuel is pelleted to have uniform sizes.
A kilo of torrefied biomass pellets can supply
gaseous fuel for more than one‐hour cooking.
The stove is locally fabricated and is named as
“Vietnam Magic Flame” Stove.  It is sold at US$
10 to 15 per unit.  The biomass pellets, which are also developed and produced by
VINASILIC, cost US$ 0.12 to 0.15 per kg.  Compared with kerosene and LPG, the payback
period for the stove is within 6 months.  Moreover, VINASILIC has already started the
promotion of the stove in Vietnam and will start its commercialization of the stove and the
fuel soon to benefit the people.
For further information, please contact Professor Tran Binh (tranbinhshc@gmail.com),
VINASILIC SJ, Socialist Republic of Vietnam or Alexis Belonio, Center for Rice Husk Energy,
Philippines (atbelonio@yahoo.com).


Released:  January 20, 2010

A CONTINUOUS-TYPE RICE HUSK GASIFIER FOR WATER PUMPING

by
Alexis Belonio, Emmanuel Sicat, Roel Pranilla, and Elmer Castillo
Glory to God!!
Rice husk gasifier can now
be used to provide power
for pumping water and for
generating electricity.
Farmers can now make
use of their gasoline
engine to run with rice
husks as fuel in lieu of
gasoline. This
development is another
accomplishment of the
Center for Rice Husk
Energy Technology Center
under the CLSU-CRHET
Rice Husk Project of the
College of Engineering,
Central Luzon State
University, Science City of
Munoz, Nueva Ecija.
The gasifier powergenerating unit converts
raw rice husks to gas by
partial burning producing
combustible gas rich in
carbon monoxide (CO),
hydrogen (H2
), and
methane (CH4
).  The gas
produced is allowed to
pass through the gas
cleaning device to remove
particulates and tars
before feeding it into the intake manifold of the engine. The engine subsequently drives the
pump that provides water for crop irrigation and the generator that produces electricity for the
The Rice Husk Gasifier-Pump System
The Irrigated Rice Farm
motors used in the
gasifier and in the
gas cleaning devices.
When the pump is
detached,
moreover, the
gasifier can provide
2 kW of electricity
which can be used
for lighting or for
running motoroperated
agricultural
machines.
As shown at the above photo, the gasifier is equipped with a 30-cm diameter by 120-cm high
moving-bed downdraft reactor where rice husks are gasified.  It is equipped with a 2½- in.
electric blower that pushes the gas through the bed of rice husks.  The wet scrubber, with a
spray tower made of a 4-in. diameter by 60-cm high GI pipe, is used to remove particulates and
tar by spraying the gas with water
a rate of 2.1m
3
/hr.  The tar is
allowed to condense inside a 40-cm diameter by 120- cm high
cylindrical tank serving as a
condenser for the liquid tar.  The
condenser has a 20-cm diameter
hole in the middle to allow natural
cooling of gas.  The gas is allowed
to pass through a packed-bed filter
having a diameter of 40 cm and a
height of 60 cm. The filter uses
rice husk with bed thickness of 45
cm. It has also a secondary filter
device having a diameter of 25 cm
and a height of 60 cm.  A 13-hp rated, single-cylinder, spark-ignition engine is used to convert
the gas into mechanical power. A 3-kW, 220-volt, single-phase, AC synchronous generator is
used to produce electricity needed for the gasifier.  A 3-in. diameter centrifugal pump
commonly used in shallow- tube well pumping is driven by the engine with the use of a beltand-pulley drive.
The gasifier can pump water at a rate of 511 to 621 liter per minute with a total head of 2.0 to
2.5 meters. While pumping, it also provides 1 kWe power for running the various parts of the
gasifier and the gas conditioning devices.  It consumes rice husk fuel at an average rate of 10.3
kg per hour and produces char at a rate of 2.75 kg per hour. The gasifier requires 13 to 15
The Rice Husk Char from the Gasifier
minutes start up time to produce the combustible gases needed by the engine. The gas
generated from the reactor has a temperature of 249° to 289°C  after passing through the filter,
moreover, the gas temperature has cooled down to 39° to 43°C.  The water in the scrubber
needs to be replaced once a week or when the tar at the scrubber is already thick.  The filter
material, which is rice husks, needs to be changed every day. Once dried, this filter material
can be used again as fuel.  The engine runs at a speed of 2197 to 2385 rpm while the pump runs
at 1440 to 1689 rpm. The generator is maintained at 220 volt in order to provide the required
electrical load for the gasifier and the gas conditioning devices.  The computed rice husk
gasification rate is 147.1 kg/hr-m
2
. The amount of rice husk needed to pump water is  0.30
kg/m
3
of water.
The advantage features of this gasifier system are: (1) It uses rice husks  commonly found in rice
farming areas as fuel which can augment fuel supply for pumping water; (2) The design is
simple which can be constructed using local materials and labor; (3) The by-product can be
used as a soil conditioner which can be immediately spread in the field to increase the water
holding capacity of the soil as well as to enhance crop growth; (4)Almost no smoke during
operation and produces low CO
2
and black carbon emission; (5) Farmers who used to operate
an engine can be easily trained to operate and maintain the gasifier.  Nevertheless, the gasifier
is fuel-specific in which rice husks is the only biomass that can be used as fuel.   Mixing other
biomass will affect the performance of the gasifier.
The investment cost for the gasifer reactor, gas conditioning system as well as the engine,
generator, and pump is around P150,000.00 (as of September 2012).  Providing a shed for the
gasifier will incur an additional cost of around P25,000.00.  At P2.00 per kg of rice husks and
P54 per liter of gasoline, using the gasifier would entail a saving of around 50 to 60% on fuel
cost. Payback period for the gasifier system is less than a year.  
For further information, please contact:
The Project Director (atbelonio@yahoo.com)
Center for Rice Husk Energy Technology
CLSU-CRHET Rice Husk Project
Room 201, PHILSCAT
College of Engineering, Central Luzon State University
Science City of Munoz, Nueva Ecija, Philippines
Acknowledgment:
CRHET acknowledges Pauchon Research Foundation of Morgan Hill California for the support in carrying out this
project to develop series of micro-gasifier power generating units to benefit the rural people, especially the
farmers. The Tech Awards 2010 and the Rolex Awards for Enterprise 2008 for the funding support in the early
development of rice husk gasifiers, particularly the moving-bed downdraft-type reactor.
Released: September 2012

A TWO-BURNER RICE HUSK GASIFIER STOVE FOR BOILING COCOSAP

by
Alexis Belonio, Alvin Guadalupe, Hermes Aguila, and Francisco Cuaresma
Glory to God!!
Amid the ever increasing prices of
conventional fuel sources like kerosene, LPG,
and wood, a two-burner rice husk gasifier
stove that can effectively boil cocosap and
convert it to syrup was recently developed.
This technology is another breakthrough
project of the Center for Rice Husk Energy
Technology (CRHET) under the CLSUCRHET Rice Husk Project at the College of
Engineering, Central Luzon State University
at the Science City of Munoz, Nueva Ecija.
This project aimed to provide a cheaper way
of boiling coconut sap and converting it to
syrup by using gasified agricultural waste as
fuel, like rice husks.  By gasifying rice husks,
a combustible clean gaseous and low-cost
fuel can be generated to economically heat
and boil cocosap and convert it to syrup.
Converting cocosap to syrup would basically
require about 2 hours of boiling.  Doing this activity using
conventional fuel, about 1.1 kg of LPG is needed to
convert a liter of cocosap to syrup.  Alternatively, around
44 kg of LPG is needed to convert 40 liters of cocosap to
syrup, which costs a lot to the processors consequently
reducing the income that they can derive from cocosugar
production. On the other hand, using wood in boiling
cocosap often results in overheating the syrup which
subsequently produces crystallized sugar and darkens the
color of the finished product. Smoke emission, moreover,
contributes to unhealthy operation and results in producing
low-quality products.
The Rice Husk Gasifier for Boiling Cocosap
Burning Gas from the Stove
Basically, the
rice husk
gasifier stove is
a larger version
of the
continuous-type
stove previously
designed for
domestic use. It
also follows the
principle of a
moving-bed
downdraft
gasifier that
produces
combustible
gases by burning
rice husks in an
oxygen-starve
environment.
The gasifier basically consists of a 35-cm diameter reactor where rice husk is gasified, a char box
where char is temporarily held and gradually discharged to ensure continuous operation, a gas
pipe that delivers the gas from the reactor to the gas burners, a two-burner assembly where 20-liter capacity kettles are heated to boil cocosap on a drum-type burners, and a 2½-in. electric
blower that supplies the air needed for combustion of rice husks and forces the gas generated to
the burners.
Forty (40) liters of fresh cocosap
can be boiled continuously in the
stove turning it to syrup in 2
hours. The start-up time in
operating the stove is 5 to 10
minutes before combustible
gases reach the burner.  Rice
husks are consumed at a rate of
12 kg per hour, with specific
gasification rate of 125 kg/hr-m
2
.
About 4 kg of rice husks is
needed to replace a kilogram of
LPG.  The gas temperature
ranges from 209° to 258°C.  The
Boiling of Cocosap in the Gasifier Stove
computed heat output is 9,020 kcal/hr.  It takes around 15 to 20 minutes to boil 40 liters of
water/cocosap, sustain the boiling until the sap turns to syrup. The gasifier is manually operated
by loading rice husks into the reactor through a feed hopper and by removing gradually the char
with the use of a sweeper.  About 3.6 kg of char is produced per hour.  One person can attend
four units of the gasifier at a time.
Pictorial of the Conversion of Cocosap to Syrup Using the Rice Husk Gasifier Stove
The advantage features of the gasifier stove
are: (1) It is a good alternative to LPG-fueled
stoves since the intensity of firing is also easily
controlled; (2) Almost no smoke during
operation thus providing a clean environment
while boiling the sap; (3) Rice husks are
available and hauling cost is very minimal or
sometimes free at all; and (4) The by-product
of the stove, which is char, can be used to
improve the soil condition in the coconut tree
plantation which subsequently improves the
production of sap in terms of quantity.  Just
like any other equipment, however, the use of
this two-burner rice husk gas stove has also
limitations which include the following: (1) A
power supply line is needed to energize the
blower; and (2) Training on the operation and
maintenance of the stove is required to fully
understand its proper operation and to lengthen
its service life.
The total investment for the gasifier stove, as
Series of Fabricated Rice Husk Gasifier Stove
for Boiling Cocosap
of July 2012, varies from P70,000.00 to P150,000.00 (excluding freight and transport cost)
depending on the type of accessories needed and degree of automation.  The operating cost of the
stove is computed at a maximum of P30.17 per hour. In terms of the quantity of coco sap and of
sugar, the operating cost of the stove is P2.01 per liter of coco sap and P14.08 per kg of sugar.
The investment cost for the stove can be recovered within 5 months, against the use of an
industrial-size LPG stove.
Further development is being done with regard to the use of the gasifier for jacketed kettle, for
crystallization of sugar, for steamer/dryer, and for micro gasifier for power supply particularly
for areas where the processing plant is located far from the grid.
For further information, please contact:
The Project Director (atbelonio@yahoo.com)
CLSU-CRHET Rice Husk Project
Room 201, PHILSCAT, Central Luzon State University
Science City of Munoz, Nueva Ecija, Philippines
Released:  August 2012

TWO-BURNER RICE HUSK GAS STOVE FOR DOMESTIC OR INSTITUTIONAL COOKING OPERATION

Engr. Alexis Belonio
Project Director
Reactor
Chimney
Appropriate Technology Center
Central Philippine University
Iloilo City, Philippines
Good news to everybody!
The two-burner rice husk gas
stove technology is already
available for domestic
household or for institutional
use such as restaurant, school
canteen, andsmall hotels.
Instead of spending fuel for
LPG, a rice hull fuel gas stove
is a good alternative to reduce
fuel cost. Rice husk is gasified
inside the reactor and the gas
generated is ignited in the
burner to produce luminous
bluish flame for cooking.
The two-burner rice husk gas
stove technology is another
development in line with rice
husk gasification project of the Department of Agricultural Engineering and
Environmental Management of the College of Agriculture, Central Philippine University
in Iloilo City, Philippines. This technology was developed with the assistance fromthe
group of undergraduate agricultural engineering students Norman Apote, Daniel Belonio,
and Lucio Larano.
Secondary
Burner
Primary
Burner
Gas Pipe
Ash
Chamber
The two-burner rice husk gas stove as shown consists of (1) Primary and Secondary Gas
Burners - where the gas is burned to produce luminous blue flame color, (2) Fuel Reactor
- where rice husk is gasified during operation by burning the fuel withlimited amount of
air, (3) Char Chamber – where burned fuelis discharge fromthe reactor after
gasification, (4) Blower – which supplies the needed amountof air for gasification, (5)
Char Lever – which discharge burned rice hull after gasification, (6) Control Switch –
which increase or decrease the flame intensity, (7) Gas Pipe – which convey the gas
generated fromthe reactor to the burner, and (8) Chimney – which discharges unwanted
gases .
The fuel reactor can be placed
outside the kitchen while the
burner can beplaced inside for
much cleaner operation. Unwanted
gases can be discharged outside the
kitchen through a chimney that can
be extended through the wall or
roof.
Flammable gas, primarily of
carbon monoxide, hydrogen, and
methane are produced during
operation as the burning fuel
moves down the reactor. Both
burners can be used at the sametime and can be
finely controlled using a ball valve as well as a
rotary switch.
The stove consumes 2.5 kilogramof rice husk per
load at 40 to 45 minutes continuous operation.
The energy input for the blower is 44 watts at 220
volt line. The specific gasification rate is 126.2
kg/hr-m
2
while the fire zone rate is 1.75 cm/min.
Ignition of fuel and gas will only tookabout 2
minutes. The advantage features of the stove are as follows: (1) Easy to start with almost
no smoke at all, (2) Convenient to operate by using ball valves and switch knob to control
the flame, (3) Clean to operate with no fly ashes,(4)
Low operating cost since it uses rice husk as fuel
and minimal amount of electricity, and (5)
Affordable.
The investment cost for the stove is P8,500.00 per
unit (Table-Top Model) and a savings of P4,887.91
on fuel cost can be derived within one year of
operation as compared with the use of LPG stove.
The technology is now in commercialization stage.
Interested organizations to adopt this technology
may contact the Project Director, Appropriate
Technology Center, Department of Agricultural
Engineering and Environmental Management,
College of Agriculture Central Philippine
University, Iloilo City, Philippines. Telephone
number 063-33-3291971 loc 1071, email ad atbelonio@yahoo.com, and mobile phone
063-0916-7115222

SMALL-SCALE RICE HUSK GASIFIER POWER-GENERATING UNIT

• The small-scale rice husk gasifier power-generating unit has a
rated power of 10 to 100 kWe.
• The system combines the process of gasification of biomass to
produce combustible gases and the subsequent conditioning of
gas (cleaning and cooling) to make it suitable as fuel for internal
combustion engines.
• The gas, which is derived from burning rice husks in an oxygenstarved environment inside a reactor, is a mixture of carbon
monoxide (CO), hydrogen (H2), and little amount of methane (CH4).
• The plant is designed to produce mechanical power and
electrical power. In the latter, however, the gasifier needs to be
coupled to a generator.
• The size of the plant varies from 10 kWe up to less than 100
kWe, depending on the required power and on the available
supply of rice husks.

• The gasifier reactor operates on a moving-bed downdraft
mode with no grate. Air is supplied by a blower on a positive
pressure mode.
• Air is preheated at the reactor before it is used for burning
rice husks.
• A temperature of around 800 to 1000 C is maintained at the
reactor during operation.
• Fire zone is maintained at the middle of the reactor where
fuel and air react producing combustible gas.
• Rice husk is fed at the top of the reactor manually or with
the use of an elevator. Char is discharged from the bottom
by means of a sweeper, scraper, and/or conveyor.
• The gas is then cleaned by spraying it with water and by
mechanically-screening it with the use of wet scrubber and
filters to remove dusts, tars, and particulates.
• The gas produced from the reactor is fueled to a
reconditioned surplus spark-ignition engine or by means of
compression-ignition engine operating on a dual fuel mode.
• The engine is directly coupled to a single- or three-phase
generator to produce electricity.
• Without any modification on the engine, it runs at 1,500 to
2000 rpm which is enough to drive a generator or other
stationary agricultural machines.
• Parasitic load is up to 15% of the overall power generated.

Advantages and Limitations

• Makes use of local resources as construction materials for the
plant.
• Makes use of reconditioned surplus spark-ignition engines as
the power-driven device for the gasifier .
• Size can be scaled-up to 100 kWe generator using
reconditioned surplus engines.
• Produces electricity either in single- or in three-phase line,
whichever is applicable.
• Provides mechanical or electrical power, whichever is needed.
• Only applicable for rice husks and needs to be redesigned if
intended to use other biomass as fuel.
• Training on operation and maintenance is a must to ensure
proper operation and longer life span of the machine.

OPERATION AND MAINTENANCE

• The engine of the gasifier plant is initially operated with
gasoline as fuel to energize the blower, pumps and motors.
The engine runs on gasoline for approximately 10 to 20
minutes from the ignition of rice husks.
• The gas coming out of the gasifier is ignited to check gas
quality whether it can now be fed to the engine. Normally,
flame color is blue-to-pink.
• Once the desired quality of the gas is obtained, the engine
fuel is shifted to producer gas by simply switching the fuelinjection valve. The producer gas is then used until the
entire operation is finished.
• Before stopping the engine, gasoline fuel is used again for
the engine for 5 minutes to clean the engine combustion
chamber from tars or particulates, if ever there is.
• Cleaning of the wet scrubber and of the tar condenser is
needed once a month to eliminate tar and particle
accumulation on the gas train.
• Filter media for the packed-bed filter needs to be backwashed during cleaning period to prevent gas suppression
during operation.
• Liquid tars collected can also be used as fuel to co-fire with
rice husks gasifier when used for thermal application.

SOCIO-ECONOMIC IMPACT

• Provides market for the local suppliers of materials for the
fabrication and construction of the gasifier plant.
• Provides employment opportunities for the rural people in the
production and operation of the gasifier .
• Provides low-cost supply of electricity.
• Makes electric power available for various social and business
activities which can improve the life of the people, especially
those in off-grid areas in the country.
• Farmers can make use of their rice husks as fuel or it can be a
source of additional income, instead of just throwing them that
contributes to environmental problem of the community.
• Provides additional revenue for the local government unit in
terms of taxes.

ENVIRONMENTAL BENEFIT

• Waste disposal problem, particularly rice husks as well as char
and tar, is eliminated.
• Greenhouse gas emission is reduced since the system
operates on the principle of gasification, approximate 0.6 kg
of CO
2
per ton of rice husks only.
• Black carbon emission is very low, only around 50 ug per m
3
of
gas.
• By-product of the plant, especially char holds water 5 to 7
times of its weight. It is a good soil conditioner material to
improve the water holding capacity of the soil.
• The silica in char can also increase the resistance of
vegetables against weevil infestation. It also provides the
silica requirement of rice plants to withstand lodging.
• Char can be used as an ingredient in the production of
torrefied pellets, which in turn can be used as fuel for
gasifier stoves for domestic cooking.
• Char, when burned further, can be used as ingredient for
the production of locally-mixed construction materials
such as cement fiber board, refractory cement, and
geopolymer .

POWER GENERATING COST AND PAYBACK PERIOD

• Investment requirement for the gasifier power-generating
unit is around P30 per watt, depending on the size and on the
complexity of parts.
• Only one person is required to operate the entire plant.
• Power generating cost is higher for smaller unit (10 kWe)
than bigger unit (100 kWe).
• Cost to generate power ranges from P4.00 for the 100-kWe
unit to P10 per kW-hr for the 10-kWe unit.
•  Comparing with the cost from the grid of P10.00 per kw-hr, a
savings from P75.86 for the 10-kWe at 8 hours per day
operation to P9,634.76 for the 100-kWe operating at 16
hours per day can be realized.
• Payback period is around 0.9 year to 6 years if the gasifier will
be operated for 16 hours per day.
• Comparing with the cost of generating using diesel fuel for a
diesel-generator system as shown below , a savings from
P275.86 for the 10-kWe at 8 hours per day operation to
P13,642.76 for the 100-kWe operating at 16 hours per day
can be realized.  Payback period is 3 years for 10 kWe unit to
less than a year for 100 kWe plant.
• However, considering land and building for the plant
including the investment for accessories such as bucket
elevator for loading rice husks and screw conveyors for ease
of disposal of char will provide a lesser saving and slightly
longer time to recover the cost for the investment.

CONCLUDING REMARKS

• The small-scale rice husk gasifier is a simple technology that
can generate electricity from rice husks.
• The technology is a good alternative energy source for
producing electricity for decentralized electrification and for
energizing off-grid areas in the country.
• Surplus spark-ignition engines commonly used in transport
vehicles can be reconditioned to be fueled with producer
gas from the gasifier to generate electricity.
• The gasifier can be locally produced which offers economic
benefits to the local people in terms of its production and
utilization.
• Operation and maintenance of the gasifier can be done by
the local people as well as repair, in case of trouble.
• The investment and operating costs for a unit of the gasifier
is at the reach of the farmers’ organizations, millers, cottage
industries as well as by the local government units.
• A substantial savings can be realized as compared to the
cost of grid and diesel generation system. The investment
can be recovered within a shorter period when the gasifier
is to be operated for a longer period of 16 hours.

RICE HUSK GASIFIER AS SOURCE OF HEAT FOR FLATBED PADDY SEED DRYER

by:  Alexis Belonio and Billy Belonio

Drying paddy is one of the major problems of
seed growers in Nueva Ecija.  Oftentimes when
drying coincides with rainy periods, seed grains
become deteriorated because of the inability to
dry them which results in a poor germinability.  

The use of mechanical drying is the alternative
method to dry seed grains in order to assure
good quality, especially during rainy periods. The
use a flatbed dryer has been proven to be the
simplest method of drying grains since almost no
moving parts in it, except the fan.  Additionally,
using rice husks as fuel is the cheapest energy
source for heating the dryer.  However, the use
of traditional rice husk furnaces as a source of
heat for the flatbed dryer has brought lots of
problems.  The major problems or feedbacks
about the use of traditional rice husk furnaces
for the dryer are: (1) investment cost per power
output is high; (2) inconvenient to use, requiring
lots of attendance during operation; (3) smoke
emission is excessive, especially at the start up; (4) difficult to maintain the right temperature
for drying; (5) life span
is short, since parts
easily get corroded
brought about by the
intense heat; and (6)
char and ash
particulates go with the
drying air.
Schematic Drawing the Continuous‐Flow
Rice Husk Gasifier
The Gasifier as Coupled to the Flatbed Paddy Dryer

In order to overcome
these problems, a
recently developed
moving‐bed inverted
downdraft rice husk
gasifier was tested and
evaluated for the
flatbed dryer in drying
rice seeds in
Mapangpang, Munoz, Nueva Ecija.  Instead of using the traditional rice husk furnace, a rice husk
gasifier was used.  The gasifier produces combustible gases from rice husks as contrasted with
direct combustion of rice husks in the traditional rice husk furnace.  The gasifier, as shown
above, basically consists of a feed hopper, a reactor, a char chamber, a gas burner, a ladder,
and a support leg.  Rice husks are fed at the reactor through a feed hopper.  With limited
amount of air (1.25 m
3
 per kg of fuel), rice husks are burned which produces carbon.  When the
carbon gas produced reacts with air, it produces combustible gases that are rich in carbon
monoxide and hydrogen.  Burning of rice husks starts from the bottom and it moves vertically
upward along the reactor.  Hot air is introduced from the top and leaves through the char
chamber’s annular space.  The gases are allowed to pass through the particle separator before
they are burned in the gas burner.  The char is discharged by swinging the scraper at the
bottom of the char chamber.

The Burning Gas Coming Out of the Gasifier Burner
Entering the Dryer Fan
The gasifier is coupled to the
flatbed dryer by positioning its
burner 30‐cm apart from the
dryer fan inlet in offset position.
Combustible gases are
produced from the gasifier
within 15 to 20 minutes after
ignition of fuel.  Burning gas
provides the required heat for
drying seed grains at a
temperature of 39 to 43°C.  The
0.4‐meter diameter gasifier
reactor can sufficiently provide
the heat energy needed by a 4‐
ton capacity flatbed dryer;
whereas, the 0.5‐meter
diameter gasifier reactor suits
perfectly for a 6‐ton capacity
dryer.  Only one person is
needed to attend the operation
of the gasifier, that is, to load
fuel and to discharge char.  Seed
grains are dried in the flatbe
dryer using the gasifier within
12 to 14 hours consum
kg of rice husks per hour per
The Paddy Seeds Being Dried in Flatbed Dryer
Using the Gasifier.

d
ing 5 to 6
 ton
of rice seeds.  Results of tests conducted revealed that rice seeds dried in the flatbed dryer
using the gasifier has higher germination percentage of 85% and above.      
The advantages of the use of gasifier for the flatbed dryer are:  (1) It is convenient to use ‐ the
ignition time to produce gaseous fuel is very short also the loading of rice husks and the
removal of char are simple; (2) No smoke emission is observed during operation – the smoke
produced are combustible and are efficiently burned in the burner; (3) Easy to control and
provides uniform temperature for drying – the amount of heat can be easily increased or
decreased with the use of a rheostat switch or a gas valve and no wider fluctuation in the
drying temperature during operation that can be observed; and (4) Low electrical consumption
per power output – only 0.01 kWe per kWt is needed to run the gasifier.
The gasifier cost P90,000.00 which includes the reactor and the two units 2½‐in.  electric
blowers.  The electric consumption of the two blowers is 32 watts.  The investment for the
gasifier can be recovered within a year provided that drying operation will be done 20 days per
month and 9 months per year.
For further information, contact:  The Project Director, Center for Rice Husk Energy Technology,
College of Agriculture, Resources and Environmental Sciences, Central Philippine University,
Iloilo City, Philippines.  Email: atbelonio@yahoo.com and website:  www.crhet.org.  You can
also contact Engr. Billy Belonio for the technical aspect of the gasifier and the dryer at
btbelonio@yahoo.com or at +639167173476.   Interested seed processors who would like to
see the technology can contact Ms. Divina Gracia Boydon (+639164219007) at Mapangpang,
Science City of Munoz, Nueva Ecija.

Released: November 2009

DESIGN AND PERFORMANCE OF A BATCH-TYPE PLASTIC PYROLYZER

by
Victoriano B. Ocon
1
, Alexis T. Belonio
2
, and Antonio H. Co
3
1
CEO, Suki Trading Corporation, Lapu-Lapu City, Cebu
2
Project Director, CRHET- CLSU Rice Husk Project, Central Luzon State University
Science City of Munoz, Nueva Ecija
3
Project Coordinator, GIFO Project – Kanvar Enterprise, Paranaque City, Metro Manila
ABSTRACT
A batch-type plastic pyrolyzer was designed and tested to provide a locally-built
technology for proper disposal of sando-bag plastics that are commonly found dumped in landfill
areas. The plastics are shredded, washed, and thermally cracked to produce liquid fuel or
crude oil suitable as fuel blend for diesel.
The pyrolyzer consists of:  a reaction chamber equipped with electric heater to vaporize
volatile matters; a condensing chamber to liquefy the gas to produce pyrolysis liquid; a catalyst
reactor to dilute the chloride that produces furan and dioxin; and a bio-filter to eliminate
unpleasant odor from the gas. The pyrolyzer cracks the plastics at a rate of 10 kilogram per
batch in 1 hour.   The equivalent amount of liquid fuel produced per batch ranges from 1.5 to 2.0
liters, with residual liquid of 0.2 to 0.5 liter collected from the deodorizer. The temperature of the
pyrolyzing chamber ranges from 200° to 300°C while the temperature of the gas coming out of
the pyrolyzer ranges from 105° to 150°C. The weight of  the char produced after pyrolyzing
varies from 0.8 to 1 kilogram.  Moreover, it was also found out that the liquid produced from the
pyrolyzer when blended with diesel fuel at 30:70 ratio can successfully run a compression
ignition engine for a continuous test period of more than 4 hours.
Economic analysis of a larger unit of the technology installed in LGUs showed that the
pyrolyzer can contribute to saving in terms of hauling and tipping fees in disposing raw plastics
on a conventional municipal landfill or dump site and in terms of the value of the liquid fuel
produced.
Keywords: Plastic, Pyrolyzer, Pyrolysis Liquid Fuel
Paper presented at the 62
nd
PSAE Annual National Convention and 23
rd
Agricultural
Engineering Week held at Puerto Princesa City, Palawan on April 23 – 27, 2012.
INTRODUCTION
Disposal of garbage, especially sando-bag plastics which contain a mixture of low- and
high-density polyethylene plastics, is one of the major problems in the Philippines.   This is
because plastics are generally non-biodegradable and there is an excessive amount disposed
of day after day.  Wherever one goes, scattered sando-bag plastics are commonly seen on
roadsides, vacant lots, and even in market places. They are  very visible litters which are
eyesores and which cause environmental pollution. The worst scenario, they are hazardous to
human health especially when burned and inhaled. Furthermore, not only that littered plastics
spoil the attractiveness of a municipality but worse they clogged its drainage system. When
mixed with garbage, plastics inter fere in waste processing facilities and cause problems in
landfill operations.
On the average, Local Government Units (LGUs) in the country produces about 1 to 2
tons of garbage daily. Of th is amount, 70% are biodegradable while the remaining 30% are
non-biodegradable.  And, sando-bag plastics constitute about 50% of the non-biodegradable
wastes.  In a month time, an average of about 4.5 to 9 tons of sando-bag plastics is
accumulated.
Recent development, on the other hand, has shown potential to address this problem.
With this new technology, sando-bag plastics can now be properly disposed by converting them
to liquid fuel.  The process is called pyrolysis where the plastics are subjected to a moderate
temperature to break the polymer structure into smaller hydro carbon molecules in the absence
of air [1,4,6, & 7]. The advantages of pyrolysis over the other methods of disposing plastics are:
(a) the process has low energy requirement; (b) it can handle plastics which cannot be
efficiently recycled by other process; (c) the process operates at low pressure thus not needing
air; (d) the by-products have economic utilization; and (e) it does not generate pollutants since
the process is conducted in a closed  environment.  Several studies [1,3,4,& 5] pointed out that
pyrolyzing plastics can produce liquid fuel, which can be used as fuel blend for diesel.  Per
kilogram, liquid oil from plastics at a density of 0.79 g per cc, contains a heat energy of 41,858
kJ [3].
In December 2011, the SUKI Trading Corporation , in collaboration with the Garbage-In
Fuel-Out (GIFO) Project, has come up with a design of a batch-type pyrolyzer that converts
sando-bag plastics into liquid fuel [2].   Tests were conducted to determine the performance of
the machine fueled with diesel-liquid-fuel blend.  Tests were likewise conducted to assess the
usefulness of the pyrolyzer technology as an alternative means in disposing sando-bag plastics
properly, which is a primary environmental concern of Local Government Units (LGUs).
Objectives of the Study
The objectives of the study are:
(1)  To design a batch-type pyrolyzer that can convert sando -bag plastics to liquid fuel;
(2)  To test and evaluate the performance of the pyrolyzer in terms of loading capacity,
pyrolyzing temperature, energy consumption, volume of liquid fuel, and weight of
char produced;
(3)  To determine whether the liquid fuel produced from the pyrolyzer can be burned and
used as fuel blend for diesel; and
(4)  To determine its economic advantage over the present practice of disposing sando bag plastics.
METHODOLOGY
The design of the batch-type plastic pyrolyzer was carried out at Suki Trading
Corporation, Lapu-lapu City in Cebu in December 2011 .  It was based on a German technology
developed at Maiden.  The design criteria used were as follows:  Process – Slow Pyrolysis,;
Capacity – 10 kg per load; Heat Source – Electricity; Loading and Unloading – Manual; and
Construction Materials – Stainless Steel.
The design concept of the pyrolyzer included a reaction chamber, which has a cubical
shape for ease of loading plastics and of removing burnt char.  The heat source to pyrolyze
plastics was with the use of a strip electric heater so the temperature can be controlled and
uniform heating can be achieved.  A condenser was included in the design of the system to
collect the liquid fuel from the gas generated during the process.  In order to eliminate the odor
and, at the same time, to collect the residual oil, a deodorizer or catalyst reactor was integrated
in the system.  A bio-filter was also included in the system to further eliminate the odor from the
gas.
The pyrolyzer was fabricated using stainless steel plates and bars to minimize chemical
and heat corrosion problems.  The pryrolyzing chamber was made of thicker plates to withstand
increase in temperature.  The condenser and the deodorizer as well as the bio-filter were built
using thinner stainless steel sheets.  Stainless steel bars were used as support frames for these
different devices.  
The performance of the pyrolyzer was tested using assorted sando-bag plastics as
feedstock. The samples were shredded into uniform sizes of about 1 cm by 1 cm. Shredded
plastics were then washed in a dipping vat and subsequently sprayed with water to remove
impurities.  Before loading into the reaction chamber, the samples were allowed to dry for 1
hour.
The weight of shredded plastic samples was taken before loading into the reaction
chamber using a 25-kg capacity weighing scale.  During the tests, the temperature of the
reaction chamber was measured by installing a type-K thermocouple wire sensor at the bed of
the samples at one end and attaching to a digital thermometer at the other end. The same
measuring device was used in recording the temperature of the gas generated from the reaction
chamber. The volume of liquid fuel collected from the condenser and from the bio-filter was
also taken using a 1000-ml volumetric flask. After pyrolyzing the plastics, the weight of char
produced was also measured using a spring scale. The pyrolysis oil obtained was blended to
diesel fuel at a ratio of 30 to 70 and then fed into the diesel engine to determine whether the oil
produced can be used as supplementary fuel.
The cost of pyrolyzing plastics against that of the conventional method of dumping
plastic wastes on a landfill was also compared.
RESULTS AND DISCUSSIONS
Design Description of the Pyrolyzer
The plastic pyrolyzer, as shown in Figure 1, is a batch type consisting of the following
major components: (a) Reaction Chamber, (b) Condenser, (c) Deoderizer, and (d) Bio-Filter.
The Reaction Chamber is where shredded plastics are thermally cracked by heating them at a
relatively low temperature for a period of one hour.  The chamber is made of two layers of
stainless steel, serving as the inner and outer layers, with a total volume of 0.5 m
3
. The inner
layer is 3-mm thick while the outer layer is 1 mm.   Between the inner and the outer layers is a
10-cm thick rock wool serving as heat insulation.  A 3-kW electric strip heater is embedded
inside the reaction chamber to heat the plastics during the process.  The gas produced from the
pyrolysis exits through a 2-in. diameter stainless steel pipe located at the upper end of the
reaction chamber.  Moreover, the reaction chamber can be opened from the top to load the
feedstock and to discharge the char.
Figure 1. The Batch-Type Plastic Pyrolyzer Showing the Various Major Components.
The condenser, on the other hand, is a 1-mm thick stainless steel cylinder with an inlet
at the top and an outlet at the bottom to facilitate passage of the gas. The function of the
condenser is to liquefy the moisture in the gas to produce pyrolysis oil or liquid fuel. A 1-in.
diameter drip pipe with ball valve is provided at the bottom of the condenser to facilitate
discharge of the oil in every operation. The deodorizer, which has a 0.5-m
3
volume and is
situated next to the condenser, is made of a 1-mm thick stainless steel box with mixture of rice
husks and a catalyst as filter to eliminate the odor from the gas.  As the gas passes through the
filter layer, the catalyst dilutes the chlorides that produce furans and dioxins thus eliminating the
odor from the gas.  The residual oil is collected from the bottom of the deodorizer through a drip
pipe with ball valve. The bio-filter is a 0.3-m
3
cylindrical chamber made of 1-mm thick stainless
steel sheet. It has an activated carbon inside to further filter the gas thereby removing
unpleasant odor from the gas.  The gas generated is released through a 2-in. chimney and is
subsequently flared.
Test Performance
Results of three separate runs for the performance testing of the pyrolyzer are shown in
Table 1 below. Using 10 kilograms of shredded plastics, which were loaded in the reaction
chamber and then thermally cracked for one hour, in each run, 1.8, 1.5 and 2.0 liters of liquid
fuel was obtained from the condenser for the 1
st
, 2
nd
and 3
rd
run, respectively.  The resultant
volume of the residual liquid collected from the deodorizer was 0.3, 0.2, and 0.5 liter for the 1
st
,
2
nd
, and 3
rd
run, respectively.  On the other hand, the temperature at the reaction chamber was
measured from 230 to 250C for the first run, 200 to 225C for the second run, and 240 to
300 for the third run. The temperature of the gas coming out of the pyrolyzer was measured at
110 to 125C for the first run, 105 to 115C for the second run, 130 to 150C for the third run.
Results also showed that the weight of char produced after pyrolyzing was 0.9, 0.8, and 1 kg for
the 1
st
, 2
nd
, and 3
rd
run, respectively.
Table 1. Results of the Performance Testing of the Pyrolyzer.
Run 1  Run 2  Run 3
Weight of Shredded Plastics (kg)  10  10  10
Operating Time (hr)  1  1  1
Temperature of the Reactor (C)  230-250  200-225  240-300
Gas Temperature (C)  110-125  105-115  130-150
Volume of Oil Produced (liter)  1.8  1.5  2.0
Volume of Residual Oil (liter)  0.3  0.2  0.5
Weight of Char Produced (kg)  0.9  0.8  1
Specific Liquid Fuel Produced (liter/kg)  0.21  0.17  0.25
Percentage Liquid Fuel Produced (%)  16.6  13.4  25.0
Percentage Char Produced (%)   9  8  10
1/ Computed as Total Volume of Oil Produced x Density of Oil x 100 / Weight of Plastic
2/ Computed as Weight of Char Produced x 100 / Weight of Plastic
The percentage amount of oil obtained from plastics was calculated at 13.4 to 25.0% per
unit weight of pyrolyzed plastics and, the percentage weight of char produced per kg of plastics
ranges from 8 to 10%.
The pictorials of the shredded plastics used as samples as well as the liquid fuel
obtained from the condenser and from the deodorizer including the char produced from the
reaction chamber are shown in Figure 2 below.
Separate tests of the pyrolysis oil obtained from the pyrolyzer revealed that the liquid
fuel is combustible and can be used as fuel b lend for diesel. By blending liquid fuel  and diesel
at 30:70 ratio, a 4-stroke, single-cylinder 16-hp diesel engine can be continuously run for more
than 4 hours.  No smoke emission was observed from the engine when liquid fuel is blended
with diesel.
(a)    (b)    ( c )
Figure 2. The Sample of: (a)  Shredded Plastics, (b) Liquid Fuel, and (c) Char Produced from
the Pyrolyzer.
Operating Cost
Economic analysis of the plastic pyrolyzer was based on the larger models of the
machine, which are presently installed and operated in  two Local Government Units. The
pyrolyzer has a loading capacity of 50 kg per load and can process 150 kilos of plastics (i.e.,
equivalent to three loads) a day and subsequently produces 30 liters of liquid fuel.  It requires 6
kW of electricity to heat the plastics for a period of 1 hour.  Moreover, the shredder which was
used to chop the plastics has a capacity of 80 to 100 kg per hour and is driven by a 12-hp diesel
engine.
The total investment cost for the technology is P1.1 million (i.e., P680,000.00 for the
pyrolyzer and P420,000 for the plastic shredder).  As shown in Table 2, the total operating cost
per day to pyrolyze shredded plastics and turn them into liquid fuel is P1,147.34.  In terms of per
Table 2. Operating Cost Analysis of Using the Pyrolyzer (As of April 2012).
1/ Life Span - 7 years
2/ Straight line with 10% salvage value
3/ 24% of the total investment cost
4/ 10% of the total investment cost
5/ 3% of the total investment cost
6/ 1.2 liters per hour at P47 per liter
7/ 6 kW at P10 per kw-hr, 3 hours operation per day
8/ Two (2) persons @ P250.00 per 8 hour-day
unit basis, the cost to pyrolyze plastics, which includes fuel, electricity and labor, is P7.65 per kg
and the cost to produce liquid fuel is P38.24 per liter.
The payback period analysis (Table 3) was done to determine whether the investment is
worthwhile.  As shown in the table, the total cost incurred per day for the conventional method of
garbage disposal is P114.38 for one ton and P228.75 for two tons.  Considering the volume of
liquid fuel produced of 30 and 60 liters per day at P 47.00 per liter, the investment costs for the
pyrolyzer and for the shredder can be recovered for a period of 2 years for a garbage production
of one ton per day.  For two tons of garbage production per day, the total investment cost can
be recovered in just one year.
Load Per Batch (kg)  50
Loading Frequency per day   3
Loading Capacity per Day (kg)  150
Expected Oil Produced (liter/day)  30
Investment Cost (P) 1/
Pyrolyzer  680,000.00
Shredder  420,000.00
Total  1,100,000.00
Fixed Costs (P/day)
Depreciation 2/    271.23
Interest on Investment 3/    72.33
Repair and Maintenance 4/    30.14
Insurance 5/    9.04
Sub-Total    382.74
Variable Costs (P/day)
Fuel Shredder 6/    84.60
Electricity 7/    180.00
Labor 8/    500.00
Sub Total    764.60
Total Costs (P/day)    1,147.34
Operating Cost per Hour     254.96
Pyrolyzing Cost (P/kg of Plastic)     7.65
Oil Production Cost (P/liter)   38.24
Table 3. Payback Period Analysis of the Pyrolyzer.
Garbage Production (Tons per day)  1  2
Weight of Sando-Bag Plastics (Tons per
day)  0.15  0.3
Tipping Fee for Sando-Bag Plastics (P) 1/  105  210
Hauling Fee for Sando-Bag Plastics (P) 2/  9.38  18.75
Total Cost Per Day (P)  114.38  228.75
Total Cost Per Month (P)  3431.25  6862.50
Volume of Liquid Fuel Produced (liter)  30  60
Value of the Liquid Fuel Produced (P) 3/  1410.00  2820.00
Payback Period (Year)  2  1
1/ At P700.00 per ton tipping fee
2/ At P2,500 per truck hauling fee, one truck at 4 tons per load
3/ Valued at P47.00 per liter of liquid fuel
CONLUSIONS AND RECOMMENDATIONS
Based on the above results of the study, the following are concluded:
1.  The pyrolyzer performs according to the design.  Shredded plastics can be converted
into liquid fuel employing the process of thermal cracking combined with condensing
and filtering of gas to eliminate toxic gases and unpleasant odor.
2.  The liquid fuel produced from the pyrolyzer can be successfully blended with diesel
to run compression ignition engines.   Since it is also combustible, it can also be
used for other applications such as heating boilers, industrial cooking, kiln firing, and
many others.
3.  The pyrolyzer is an effective means of disposing sando-bag plastics over the
conventional method, which is disposing plastics on dump sites. It is also an
effective means of converting sando-bag plastics into fuel, which helps address the
fuel shortage.
It would be more advantageous to integrate the pyrolyzer in the garbage gasification
system in order to further degrade burnt plastics, which can still be used to produce heat or
electricity. Designing the system to operate on a continuous-mode can minimize the problem of
loading plastics and unloading of char.
REFERENCES
[1]  Behzadi, S. and M. Farid. Liquid fuel from Plastic Wastes in New Zealand. Department of
Chemical and Material Engineering. The University of Aukland. 30pp
[2]  Belonio, A.T., Ocon, V. B., and A. H. Co. SUKI Garbage-to-Energy Processing Technology.
Paper presented during the Symposium on Peso from Waste ++ (Mitigating Measures for
Climate Change) hel d at Legislative Building, Provincial Capitol, Matti, Digos City on February
10, 2012.
[3]  Guntur, R., Deva Kumar, M.L.S., and K. Vijaya Kumar Reddy. Experimental Evaluation of a
Diesel Engine with Blends of Diesel-Plastic Pyrolysis Oil.  International Journal of Engineering
Sciece and Technology. Vol. 3 No. 6. June 2011. Pp 5033-5040.
[4]  Osueke, C.O. and I.O. Ofonda. Conversion of Waste Plastics (Polyethylene) to Fuel By
Means of Pyrolysis. International Journal of Advanced Engineering Sciences and Technologies.
Vol. 4, Issue No. 1. Pp-021-024.
[5] Sadaka, S. Pyrolysis. Center for Sustainable Environmental Technologies/Department of
Agricultural and Biosystem Engineering. Iowa State University. Nevada, IA 50201, USA. 25pp.
[6] UNEP. 2009. Converting Waste Plastic into a Resource: Compendium of Technology.
United Nations Environmental Program. Division of Technology, Industry and Economics.
International Environmental Technology Center. Osaka/Shigg. Japan. 51pp.
[7] Wikipedia. Pyrolysis. http://en.wikipedia.org/wiki/pyrolysis