(p580) Reducing Heat Losses in Everyday Melting Practice - A Case Study

摘要

A primary goal in energy intensive processes is to increase their energy efficiency. The best performing steelcompanies using Electric Arc Furnaces (EAF) have already installed the latest technologies that maximize the rateof energy input to the process, typically: Water cooled split shell furnace Ultra High Power (UHP) transformer Oxy-fuel sidewall burners with supersonic oxygen injection Carbon injection for foamy slag Post-combustion Off-gas analysis Shaft furnace/Scrap preheatingThe implementation of these technologies allows the highest productivity levels. For example, water cooled steelpanels for the walls of the EAF permit very high energy input intensity without damaging the furnace walls. Thewater cooling for these walls can extract energy at a fairly constant rate regardless of the energy intensity. Thus,energy loss per unit of time to the walls stays relatively constant so the overall losses per tonne of steel decreasesas the productivity increases. UHP, oxy-fuel burners, post-combustion also increase the rate of energy input. Agood foamy slag shields the furnace walls from the arc thus it reduces the energy losses of the furnace. It alsostabilizes the arc such that electrical energy losses are also reduced. Scrap preheating using a shaft furnace orany other method reduces the energy requirement of the furnace and in such technologies; the energy used topreheat the scrap comes from the EAF off-gases.Each one of the technologies listed above is commercially available through several EAF suppliers. This casestudy will show how it is possible to further reduce the energy consumption in a world class modern EAF (309kWh/tap tonne for 100% scrap) using simple techniques and principles designed to minimize heat losses.