Dynamic analysis of a furnace off-gas energy recovery system integrating heat from batch-wise metal casting

Waste heat recovery has become a vital part of increasing the energy efficiency of metal‐producing industry, and several Norwegian ferro‐alloy plants have implemented electricity generation from furnace off‐gas. Another interesting option for energy recovery is the heat released during casting of metal, but this is rarely utilized today as the intermittent availability makes exploitation challenging. This study explores the feasibility of incorporating heat captured from batch‐wise metal casting into an off‐gas steam cycle system to mitigate these challenges while increasing the system's power output. A dynamic model is used to study the potential gains and necessary modifications of integrating this secondary heat source. This includes implementation of a steam accumulator for steam buffering and upsizing of the steam turbine. It is found that an increase in power generation proportionate to the increased heat input is achievable with a large steam accumulator and a moderately upsized steam turbine.