A cross draft gasifier was designed and constructed using mild steel
sheetwith4.3 mmthicknesswitha volume is 0.714 m3. The totalheight of
the gasifier is 1.34 m. Hopper is the primary storage area for the fuelwood.
Feed stock size for long-stick wood of length 68 cm and thickness of 6 cm
is placed into the top of the hopper through the inlet. The hopper is
designed in such away that it is able to hold wood,which can produce the
gas continuously for 5 to 6 h. Initially, charcoal pieces are first loadedup to
air nozzle height. Then long-stick wood is packed up to the full capacity of
the hopper. Hearth is made up of castable cement with a mild steel
exterior cladding to encounter higher temperature up to 1600 °C. Cuda
and Ziak [7] fabricated the cross-draft gasifier, which has an operating
temperature of 1500 °C though they used it onlywith charcoal feed stock.
The air fromthe blower for partial combustion enters the hearth through
air nozzle.Theairnozzle tube ismadeupof SSmaterial 1.5-inchdiameter.
There are two air nozzles fixedwith adjacent side of the hearth. It is shown
in Fig. 1. The positioning of the grate belowthe hearth zone in the gasifier
is to help the reduction reactions. The grate directly supports the
combustion zone and must be capable of letting ash fall through without
an excessive loss of fuel. In addition, the grate is used to control reactor
pressure drop and hence to maintain the gas production rate. Ten
kilograms of charcoal is placed on a grate and is ignited by twofire ports. It
appears that the blower is run in suction mode to draw air in through the
fire ports during the charcoal ignition. 60 kg of long-stick wood is placed
on top of the charcoal. The fire ports are closed and the supplied flame
through the two fire ports stops. The fan is run in blower mode and the air
enters frombelowthe bed. The primary air for pyrolytic gasification enters
at the bottomand moves up, forming gas in the flaming pyrolysis zone as
shown in Fig. 2. This airflow is measured by pressure drop across a
restriction. Gases produced by the wood and charcoal exit through a gas
port. This gas is combusted and the gas flow rate (via pressure difference)
and the producer gas flame temperature are recorded. Drying, pyrolysis,
and combustion of the packed bed continue until the flame at the gas port
goes out. We have examined the quantity and the nature of the ash
collected after the different performance trials. The quantity of ash 3%
collected with the cross draft mode is smaller compared with that of the
bottom lit mode at 5%. The quality of the gas also is better due to the
cracking of tar in the cross draft mode.
A cross draft gasifier was designed and constructed using mild steelsheetwith4.3 mmthicknesswitha volume is 0.714 m3. The totalheight ofthe gasifier is 1.34 m. Hopper is the primary storage area for the fuelwood.Feed stock size for long-stick wood of length 68 cm and thickness of 6 cmis placed into the top of the hopper through the inlet. The hopper isdesigned in such away that it is able to hold wood,which can produce thegas continuously for 5 to 6 h. Initially, charcoal pieces are first loadedup toair nozzle height. Then long-stick wood is packed up to the full capacity ofthe hopper. Hearth is made up of castable cement with a mild steelexterior cladding to encounter higher temperature up to 1600 °C. Cudaand Ziak [7] fabricated the cross-draft gasifier, which has an operatingtemperature of 1500 °C though they used it onlywith charcoal feed stock.The air fromthe blower for partial combustion enters the hearth throughair nozzle.Theairnozzle tube ismadeupof SSmaterial 1.5-inchdiameter.There are two air nozzles fixedwith adjacent side of the hearth. It is shownin Fig. 1. The positioning of the grate belowthe hearth zone in the gasifieris to help the reduction reactions. The grate directly supports thecombustion zone and must be capable of letting ash fall through withoutan excessive loss of fuel. In addition, the grate is used to control reactorpressure drop and hence to maintain the gas production rate. Tenkilograms of charcoal is placed on a grate and is ignited by twofire ports. It
appears that the blower is run in suction mode to draw air in through the
fire ports during the charcoal ignition. 60 kg of long-stick wood is placed
on top of the charcoal. The fire ports are closed and the supplied flame
through the two fire ports stops. The fan is run in blower mode and the air
enters frombelowthe bed. The primary air for pyrolytic gasification enters
at the bottomand moves up, forming gas in the flaming pyrolysis zone as
shown in Fig. 2. This airflow is measured by pressure drop across a
restriction. Gases produced by the wood and charcoal exit through a gas
port. This gas is combusted and the gas flow rate (via pressure difference)
and the producer gas flame temperature are recorded. Drying, pyrolysis,
and combustion of the packed bed continue until the flame at the gas port
goes out. We have examined the quantity and the nature of the ash
collected after the different performance trials. The quantity of ash 3%
collected with the cross draft mode is smaller compared with that of the
bottom lit mode at 5%. The quality of the gas also is better due to the
cracking of tar in the cross draft mode.
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