Energy conservation using Waste Heat Recovery System (WHRS) in metal casting - an approach for sustainable manufacturing

The higher the volume of production, the amount of resources consumed and emissions to the environment also increases. It resulted as an impetus to improve sustainability of the manufacturing processes. Sustainable manufacturing will lead to the production of required components using the processes that reduces harmful environmental impacts, conserve energy and natural resources, and are cost-effective. In this paper we are focusing on energy conservation in a most energy-intensive process of metal casting. Here in we discuss an innovative technique of implementing a methodology which involves recovery of energy from fettled casting - using it for preheating raw material which thus reduces energy consumption of furnace - with the help of a Waste Heat Recovery System (WHRS) which is otherwise lost to the surrounding during atmospheric cooling on a shop floor. In a basic experimental set up, after preheating, the raw billets was found to take 2.94 % less energy for melting as compared to conventional method of cooling it in the shop floor. This technique has been further improvised by modifications in a basic set up like surrounding basic set up with a semi cylindrical enclosure with end faces open resulting in the waste heat recovery up to 4.55 % and surrounding basic set up with a semi cylindrical enclosure with end faces closed resulting in the waste heat recovery up to 6.78 %. Extending this savings to Aluminium castings produced per year in Indian foundries, of around 950,000 metric tons, the total amount of energy saved is a significant number. The calculations show energy savings as high as 34.62 GWh, which can be interpreted in monetary terms approximately to Rs 31.16 crores per year for Indian foundries.