A multi-parameters evaluation on exergy for hydrogen metallurgy

Abstract

The traditional iron and steel industry (ISI) began to implement technological innovations aimed at lowering carbon footprint and emissions, resulting in hydrogen metallurgy gradually becoming a new trend of green development in ISI. However, there is a lack of comprehensive and in-depth analysis of energy-exergy based on the second law of thermodynamics in the current research of hydrogen metallurgy. To address these issues, a numerical calculation model of hydrogen metallurgy based on material-energy-exergy is established. Two novel evaluation indexes are introduced to better evaluate the impact of various parameters on hydrogen metallurgy. It was found that the exergy intensity is mainly affected by the amount of reducing gas, and increasing the preheating temperature of the ore cannot always reduce the exergy intensity due to the influence of element conservation. And when the ore preheating temperature is higher than 623 K, the exergy utilization efficiency decreases. After calculation, the lowest exergy intensity is 1.23 × 107 kJ/t-DRI when the H2 content is 41.37% and the ore temperature is 773 K. Furthermore, a simple process is designed to recover a substantial volume of unreacted gas from the furnace top gas. Overall, this study can serve as a reference for actual hydrogen metallurgy production.