Dynamic Analysis of Energy Recovery Utilizing Thermal Storage from Batch-Wise Metal Casting

Abstract

The thermal exergy contained in the liquid metal in ferroalloy production makes it an interesting source for energy recovery. The heat released during casting is rarely utilized today. This work investigates the feasibility of continuous power production from batch wise ferroalloy casting using an energy recovery system concept that includes a thermal energy storage to buffer captured heat between casting cycles and enable a more stable heat supply to a Rankine cycle. A dynamic model of the heat recovery and storage system was developed, and a demonstration case applied to evaluate basic system behaviour. Every two hours, liquid metal at 1450 °C was poured into moulds and placed in a cooling tunnel. With the investigated concept, only 54.6 % of the available heat was captured into the system, indicating a potential for further improvements. Overall, the system was able to output 667 kWhel from the 4 005 kWh of thermal exergy available in the metal in each casting cycle, equivalent to an exergy efficiency of 16.7 %.