Energy-carbon comprehensive efficiency evaluation of hydrogen metallurgy system considering low-temperature waste heat recovery

TL;DR

This paper introduces a zero-carbon hydrogen metallurgy system that effectively recovers low-temperature waste heat, improving energy and carbon efficiency compared to traditional direct reduction iron processes.

Contribution

It develops detailed models and efficiency indices for a novel system integrating waste heat recovery, demonstrating its advantages over conventional methods.

Findings

The proposed system outperforms traditional DRI in energy and carbon efficiency.

Incorporating ORC and expanders enhances electricity generation from waste heat.

Sensitivity analysis confirms significant waste energy utilization potential.

Abstract

To address the lack of energy-carbon efficiency evaluation and the underutilization of low-temperature waste heat in traditional direct reduction iron (DRI) production, this paper proposes a novel zero-carbon hydrogen metallurgy system that integrates the recovery and utilization of low-temperature and high-temperature waste heat, internal energy, and cold energy during hydrogen production, storage, reaction and circulation. Firstly, the detailed mathematical models are developed to describe energy and exergy characteristics of the operational components in the proposed zero-carbon hydrogen metallurgy system. Additionally, energy efficiency, exergy efficiency, and energy-carbon efficiency indices are introduced from a full life-cycle perspective of energy flow, avoiding the overlaps in energy inputs and outputs. Subsequently, the efficiency metrics of the proposed zero-carbon hydrogen metallurgy system are then compared with those of traditional DRI production systems with H$_2$/CO ratios of 6:4 and 8:2. The comparative results demonstrate the superiority and advancement of the proposed zero-carbon hydrogen metallurgy system. Finally, sensitivity analysis reveals that the overall electricity energy generated by incorporating the ORC and expander equipments exceeds the heat energy recovered from the furnace top gas, highlighting the energy potential of waste energy utilization.