Track: Energy

Abstract

Energy efficiency of furnace should be based on its ability to conserve heat within the combustion chamber. This depends mainly on the design and furnace materials selection. The coal fired furnace is common amongst the rural foundries in Limpopo province of South Africa. The coal fired furnace is used to melt aluminium scraps to cast the three legged aluminium pots commonly used as cooking utensil and sold within the local and national communities. The coal fired furnace is used due to its easy to manufacture, to operate and its low capital and running costs investment which is suitable for small batch production. However, made of a mere superposition of two steel drums, the current coal fired furnaces in rural foundries have long melting time ~ 6 hours, due to the design and material selected in manufacturing the furnace. This paper presents the analysis of design and material components of rural foundries furnaces in South Africa and studies the energy efficiency of the coal fired furnace. Technical testing of the energy balance through the furnace i.e. energy in and output was conducted. Findings show that with a heat loss of 2887.2 MJ and an energy efficiency of only 3.37%. The heat loss was one of the main contributions to the experienced long melting duration. The insufficient supply of oxygen or air into coal fuel also plays a critical role in the performance of the furnace, since combustion of coal depends greatly on the supply of oxygen or air.  To improve the heat retention and the energy efficiency, a re-design of the coal fired furnace used in the rural foundries and selection of specified new lining materials were introduced.