Abstract:
The use of coal as a substitute for charcoal is found to cause problems like odour and smoke. One of the improvements of coal before use is carbonization, in which moisture and volatile matter in the coal are reduced, resulting in coal with less odour and smoke, which can be briquetted for domestic use. The objectives of this research are : to devise domestic cooking stove capable of carbonizing coal at the time of cooking ; to study factors affecting stove efficiency, properties of carbonized coal, and carbonization chamber temperature in regard to the amount of fuel, the amount of coal being carbonized in the carbonization chamber ; and to develop a simple method of producing smokeless coal briquettes. The stove designed in this research is a double-walled cylindrical stove made from stainless steel 0.5 cm. thick. The space between the inner and outer walls is the carbonization chamber. Heat generated from fuel was used for cooking with over 30 percent efficiency while heat transferred through the combustion chamber wall was used for carbonizing coal at about 450 ℃ with resulting coal containing less than 20 percent by weight of volatile matter relative to dry smokeless coal, which was within the limit of low temperature carbonization. Efficiency was increased with increment of the amount of fuel used and more volatile matter was reduced. Decreasing the quantity of coal in the carbonization chamber did not show significant difference in efficiency, while improved quality coal with less volatile matter was yielded. Ice-trays were used as hand-pressed moulds conveniently to produce approx. 2.5x3.5x2.5 cm³. good quality smokeless coal briquettes. The appropriate composition for briquetting coal was 10 percent by weight of clay relative to dry smokeless coal, with no addition of lime to eliminate sulphur dioxide.