An integrative process of blast furnace and SOEC for hydrogen utilization: Techno-economic and environmental impact assessment

Abstract

The steel sector is one of the most carbon-intensive industries, and the sustainable strategies to reduce CO2 emission on integrated mill plants are discussed continuously. By renewable H-2 utilization on blast furnace (BF), it is expected to achieve both sustainable operation and CO2 emission reduction. We evaluate the application of the solid oxide electrolysis cell (SOEC) process as a source of H-2 for use as an alternative to CO as the reductant in a BF. We mathematically formulated a BF model and developed an integrated BF-SOEC process. We performed techno-economic analysis to suggest the maximum H-2 injection for the technical aspect, and demonstrated the process' economic viability, considering the learning-by-doing effects on the price of the SOEC system. We also estimated the net reduction of global warming potentials and carbon intensity. Our findings showed that the coke replacement ratio ranged from 0.255 similar to 0.334 kg(Coke).kg(H)(-1) depending on injection conditions and that 25 kg(H2).t(HM)(-1) was an acceptable maximum injection rate within the stable range of BF operating indexes. We calculated H-2 production cost to be US$ 8.84 similar to 8.88 kg,121 in the present, but it is expected to be decreased to US$ 1.41 similar to 4.04 kg(H2)(-1) H-2 by 2050. Economic parity with the existing BF process will be reached between the years 2036 and 2045, depending on the maturity of the SOEC process. Injection of 25 kg(H2)center dot(-1) can reduce CO2 emission by 0.26 similar to 0.32 t(CO2-eq).center dot t(HM)(-1) We expect that this sustainable strategy to reduce CO2 emission from integrated mill plants will widen applications of H-2 utilization in BFs if the economic efficiency of SOEC systems can be increased.