DUAL- REACTOR RICE HUSK GASIFIER FOR 6-TON CAPACITY RECIRCULATING-TYPE PADDY DRYER

by
Alexis T. Belonio
Central Philippine University
Iloilo City, Philippines
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T-Chimney
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Fuel
Loading
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Drying of paddy in a recirculating type dryer is quite
expensive nowadays. This is
because of the continued
increase in the prices of fossil
fuel, particularly diesel. At
present, a liter of diesel costs
about P38.80. With a fuel
consumption of 6 liters per hour
of diesel using a typical recirculating type dryer, about
P2,300 per day is spent on fuel
for 10 hours operation,.
Rice husk, which is a by-product of milling ofrice, is a potential biomass material
that can be used to replace diesel fuel that is commonly used in a recirculating-
type grain dryer. Gasifying rice husk on a top-lit updraft (T-LUD) mode was
proven to produce quality flame that approaches the quality of that of diesel.
Using gasifier, combustible gases can be piped-in through a remote burner for
direct use by the dryers. Since,
T-LUD type rice husk gasifier
normally operates on a batch
mode, a dual-reactor rice husk
gasifier was designed and
developed so that the reactor
can be alternately ran thereby
continuous drying operation can
be achieved.
The dual reactor rice husk
gasifier is a biomass energy
technology for thermal
application designed and
developed at the Appropriate Technology Center, College of Agriculture, Central
Philippine University, Iloilo City with the assistance from the agricultural
engineering students,Lucio Larano
and Daniel Belonio. As
schematically shown above, the rice
husk gasifier consists of the
following: two reactors, where rice
husk fuel is burned with limited
amount of air to generate
combustible gases; char chambers
where burnt rice husk isdischarged;
a momentum-type separator to
collect char particles that go with the
gas; a set of blowers that supplies
the needed air for gasification and
for cooling the reactor; a gas pipe to
convey combustible gases from the
reactor to the burner; a jet-type
burner to burn combustible gases;
and a pneumatic conveyor to
discharge char from the reactor to
the cyclone separator for
subsequent disposal.
Each reactor has a diameter of 0.5 m and a height of 1.6 m. Itis made from 1.3
mm stainless steel plate inner cylinder and 1.3 mm mild steel plate outer cylinder.
It has a 10-cm annular space where ambientair is injected to cool the inner
cylinder and subsequently used for combustion of combustible gases as well as
for the supply of hot air into the dryer. Two centrifugal 2½-in. electric blowers are
used for each of the reactor to supply the needed air for gasification and one 3-in. electric blower for the cooling of the reactors. The gas is conveyed to the jettype burner through a 3-in. diameter GI pipe equipped withgate valve to control
the flow of gases.
Performance testing and evaluation
of the gasifier showed that each
reactor canaccommodate 4 sacks of
rice husk per load with a power
output of 10.4 kW. Ignition of fuel
can be done within 2 minutes and
combustible gases can be generated
within 5 minutes. The amount of rice
husk fuel consumed averages to 29
kg per hr. Each reactor operates for
1 hour and 20 minutes before shifting
to the other. The computed specific
gasification rate and superficial
velocity of the reactors averages to 148.5 kg/hr-m
2
and 5.4 cm/sec, respectively.
The percentage amount of char produced is 35%. One person is needed to
attend in loading and unloading offuel from the reactor. Actual tests showed that
the gasifier can continuously supply the required heat that is needed by a 6-ton
capacity recirculating-type grain dryer. Heated air temperature of 45 to 60ºC can
be attained at the plenum chamber during drying. The investment cost for the
gasifiier is P200,000.00 per unit. It can be recovered within less than 1 year of
operation when operated at 10 hours per day, 20 days per month, and 8 months
per year operation.
The gasifier is an alternative device to replace the use of high cost diesel fuel. It
can help minimize the problem of rice husk disposal and also a potential source
of additional income in the production of carbonized rice husk.
Any interested organization who wishes toadopt the technology may collaborate
with the Appropriate Technology Center, Department of Agricultural Engineering
and Environmental Management, College of Agriculture, Central Philippine
University, Iloilo City, Philippines. You may contact through our landline at 063-033-3291971 loc 1071 or our mobile phone at 063-09167115222.