Comprehensive evaluation on energy-water saving effects in iron and steel industry

The production of iron and steel is energy-intensive that motivated the emergence of various energy-saving technologies to reduce energy consumption. However, the effects of water-saving brought by these energy-saving technologies are rarely examined which can lead to misevaluation of their economic feasibility. In this regard, material flow analysis (MFA) was used in this study to establish the water-energy nexus and examine the potential of water-saving and energy-saving effects in the condition of applying various mixes of the 16 technologies (Ministry of Industry and Information Technology, 2015-2016) in iron and steel industry. Meanwhile, this study classified the selected 16 energy-saving technologies into three groups: direct water-saving technology, indirect water-saving technology, and water consumption technology. The low-temperature steel rolling technology is the only water-consuming energy-saving technology in this study; its indirect specific water computation reaches 0.06 m³/t. The remaining 15 energy-saving technologies have the potential of saving water indirectly, with averaged indirect specific water-saving amounting to 0.28 m³/t. This study also built an evaluation scheme of cost-benefit analysis for energy-saving technologies. With consideration of benefits brought by water saving, eleven technologies have the potential to achieve economic feasibility compared to nine in which mere energy-saving effects being considered. The results show that if the studied 16 technologies are implemented simultaneously, the comprehensive specific energy consumption will be reduced by 4.28 MJ, and the specific fresh water consumption will be reduced by 0.68 m³. Meanwhile, this research found that the cost of most energy-saving technologies will be decreased by an average of 5.52 CNY/GJ, despite the cost of low-temperature steel rolling technology increased by 0.68 CNY/GJ. This study evaluated the cost-effectiveness of energy-saving technologies taking the benefits of water conservation into consideration. It could provide references for decision-makers to develop commercialization strategies on energy saving technologies in the steel industry.