Flow sheet model evaluation of nuclear hydrogen steelmaking processes with VHTR-IS (Very High Temperature Reactor and Iodine-Sulfur process)

VHTR-IS(超高温ガス炉-ISプロセス)による原子力水素還元製鉄プロセスのフローシートモデル解析

笠原 清司  ; 稲垣 嘉之; 小川 益郎

Kasahara, Seiji; Inagaki, Yoshiyuki; Ogawa, Masuro

VHTR-IS(超高温ガス炉-ISプロセス)による原子力水素還元製鉄プロセスのフローシートモデル解析を行った。評価対象は投入熱量とCO排出量である。原料製造,輸送,発電を含めた原子力水素還元製鉄(NHS)プロセスの投入熱量は28.4GJ/t-HQS(高品位鋼)であリ、この値は高炉製鉄(BFS)プロセスの17.6GJ/t-HQSより大きい値であった。効率化のために、水素消費量の削減と電気炉投入電力量の低減が求められる。原子力水素部分還元製鉄(NHPRS)プロセスの投入熱量は31.9GJ/t-HQSであり、部分還元鉱石の還元率と、高炉投入割合の最適化が必要になる。NHPRS, NHSのCO排出量はBFSの50%, 9%であった。還元物質が石炭から水素に変わったことと、原料輸送量が低減されたことで、CO排出量が削減された。製鉄規模を100万t/年にそろえたとき、NHSはBFSやMidrex法製鉄に近い製鉄コストであった。特に、原料コストが高価なとき、NHSが有利となった。

Flow sheet model evaluation of nuclear hydrogen steelmaking (NHS) and nuclear hydrogen partial reduction steelmaking (NHPRS) systems applying VHTR-IS (Very high temperature reactor and iodine-sulfur process) was carried out. Heat input and CO emissions of these systems were analyzed. Total net heat input to the NHS system was 28.4 GJ/t-high quality steel (HQS), including material production, material transportation, and power generation. This value was much larger than that of blast furnace steelmaking (BFS) system of 17.6 GJ/t-HQS. Reduction of hydrogen consumption in the shaft furnace and electricity consumption in the electric arc furnace were desired for lowering the heat input. Total net heat input of the NHPRS system was 31.9 GJ/t-HQS. Optimization of operation parameters such as reduction ratio of partial reduced ore (PRO) and PRO input ratio to the blast furnace is desired to decrease the heat input. CO emissions from the NHS and the NHPRS systems were 9% and 50% of that from BFS system. Substitution of hydrogen for coal and reduction of transportation weight contributed to the reduction. Steelmaking cost was also evaluated. When steelmaking scale of each system was unified to one million t-HQS/y, NHS was economically competitive to the BFS and Midrex steelmaking. And NHS was advantageous at higher cost of resources.