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The Institutional Gasifier Stove (IGS-2) consists of five main parts: a fuel storage hopper, reaction chamber, primary air inlet, combustion chamber and a 2-pot support. Experimental results indicate an average efficiency of 17% with ricehusk briquettes (two-pot configuration), 27% with wood chips and 22% with wood twigs as fuel. The stove appears to be promising for community type cooking, particularly for institutional kitchens and traditional cottage industries.
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Briquettes are produced when the raw material (e.g.: ricehusk) is forced by a screw through a heated die in a briquetting machine. The die is maintained at a very high temperature of about 300 o C. The briquettes often get partially pyrolysed at the surface and cause a lot of smoking. The briquettes are usually produced of about 50-100 mm in diameter, and have a central circular hole that facilitates better combustion.
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Die heating stove was developed to substitute the electrical die heaters by a biomass-fired stove was therefore expected to reduce briquette production cost by cutting down electricity cost. The hot flue gas from the stove could be used for preheating the rice-husk. The die of the briquetting machine passes through the stove, exposing its outer surface to the flames inside. Doors were provided for loading the fuel as well as to remove the ash. An ash scraper was fixed below the grate to remove excess ash from the furnace, which falls through the grate.
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Rice husk briquetting machines with improved screws and can be operated with diesel engines have been fabricated and demonstrated in Bangladesh by BIT. This machine could be operated in remote rural villages, which do not have access to the electricity grid and are close to the raw material supply areas. 10-15% reduction in briquette production cost was realised in diesel engine-driven machine compared to electrical drive, for ricehusk, rice straw, wheat husk, bagasse and saw dust.
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Two-pot stoves of fixed and portable designs were developed, considering the local requirements and cooking practices. The efficiency of these stoves (by Water Boiling Test) varied from 28-39% with ricehusk briquettes as fuel.
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In top-down concept, some kindling is put at the top of the fuel bed and ignited. The fire moves progressively down through the layers of the fuel. It appear to be able to burn biomass with much less smoke compared with conventional burning. Minimal smoking, can use ricehusk briquettes and wood chips/twigs as fuel.
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Improved screw for briquetting machine developed by BIT, Bangladesh.
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Improved screw for briquetting machine developed by IE, Vietnam
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Training programs conducted by IE on operation and maintenance to provide detailed knowledge on the improved briquetting machine. These trainings included theoretical description, design parameters as well as a practical session.
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Several cooking stoves were designed and demonstrated in Vietnam. Single-pot and two-pot stoves of fixed and portable types were designed considering the local requirements and cooking practices. The efficiency of these stoves (by Water Boiling Test) varied from 28-39% with ricehusk briquettes as fuel.
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The top-down burning appears to be able to burn biomass with much less smoke compared with conventional burning. In top-down concept, some kindling is put at the top of the fuel bed and ignited. The fire moves progressively down through the layers of the fuel. The main advantage of the top-down concept is minimal smoking. The two-pot top-burning stove jointly developed by the Institute of Energy, Vietnam and AIT, Thailand could use ricehusk briquettes and wood chips/twigs as fuel.
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This briquetting machine was designed based on a prototype machine imported from Thailand and the experience of Bangladesh. It uses a new set of screw and die developed by Institute of Energy (IE), Vietnam.
It is driven by an electrical motor of size 10 HP against 20 HP motors used in the earlier designs. and saves electrical energy of up to 26%.
The screw and die designs were based on extensive research carried out at IE.
It saves energy, has easy fabrication of screw and die, less expensive, and is easier to install/remove. |
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