Improving furnace performance by waste heat recovery-economic analysis

Abstract

Combustion type furnaces used to melt metals for casting or to heat materials for change of shape or change of properties have low energy efficiency due to energy losses in different areas and forms, especially in the form of exhaust gases. There are many ways to recover the waste heat of exhaust gases. Most of them use the sensible heat in flue gases for combustion air preheating, charge preheating and to generate steam or hot water. In this study economic analysis is applied to a furnace for forging equipped with combustion air preheater. The thermal efficiency increases from 14.86% to 21.87% and the yearly total running cost decreases from 720542 € to 716532 €, that means an economy of 4010 € per year. This analysis provides information on investment cost and the economic and environmental benefit by using the waste heat for combustion air preheating.