鉄と鋼
Online ISSN : 1883-2954
Print ISSN : 0021-1575
ISSN-L : 0021-1575
102 巻, 8 号
選択された号の論文の6件中1~6を表示しています
製銑
論文
  • 小暮 聡, 横田 恭平, 西村 恒久, 国友 和也, 岡崎 潤
    2016 年 102 巻 8 号 p. 425-433
    発行日: 2016年
    公開日: 2016/07/31
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    CO2 emissions in steel works accounts for about 15% of those in Japan (2015), and most of those are from blast furnace iron-making process. To reduce CO2 emissions, utilization of woody biomass in blast furnace is considered. Woody biomass has the characteristic of carbon neutral and high reactivity. So CO2 emissions can be reduced by the use of woody biomass as coke substitution. High reactivity of reducing agent is expected to decline thermal reserve zone “Trz” temperature, which causes improvement of reaction efficiency in the blast furnace and lowering of reducing agent rate. To verify the effect of the use of woody biomass on thermal reserve zone temperature, we executed experiment to evaluate the effect of charcoal coexisting in the ore layer on reduction behavior of iron oxide with the adiabatic blast furnace inner reaction simulator (BIS). With heat and mass balance analysis, we evaluated the effect of declining Trz temperature on lowering of reducing agent rate and the effect of utilization charcoal as coke substitution on reducing CO2 emissions in blast furnace process.
    As a result, charcoal lowered the Trz temperature and carbon consumption. We estimated that charcoal can reduce CO2 the amount of CO2 emissions 33%. So that, we think that charcoal can be used as coke substitution.
  • 村井 亮太, 浅沼 稔, 佐藤 道貴, 井ノ口 孝憲, 寺田 周雄
    2016 年 102 巻 8 号 p. 434-442
    発行日: 2016年
    公開日: 2016/07/31
    [早期公開] 公開日: 2016/05/20
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    Injection of plastics into blast furnaces as an alternative reducing agent has been carried out for the purpose of mitigation of carbon dioxide emissions. Several studies on the pyrolysis of plastic particles have been reported, however flow behavior of plastic particles or unburnt char in actual blast furnace is not clear.
    In this study, hotmodel experiments and thermogravimetry analysis were conducted for the modeling of gasification behavior of plastic particles, then flow behavior of plastic particle and unburnt char in a blast furnace was calculated by numerical simulation. According to the observation results of gasification experiment, volatile matter of plastics seems to be evolved at the surface of the particles. Regarding reaction of char derived from plastics, thermogravimetry analysis showed that rate of gasification of unburnt char depended on the rate of heating. Gasification rate in the case of rapid heating condition tended to increase.
    As the results of numerical simulations, initial diameter of plastics and char diameter determined the flow behavior in the blast furnace. When relatively small plastic was injected or diameter of unburnt char was small, unburnt char went upward along with gas flow and most of it might be consumed at the cohesive zone. On the other hand, when relatively coarse plastics was injected and diameter of unburnt char was relatively coarse, it was suggested that unburnt char accumulated around the deadman.
    Therefore, it is considered that fine plastics injection is desirable for the stable operation of blast furnace.
製鋼
論文
  • 中井 由枝, 鷲見 郁宏, 菊池 直樹, 田中 高太郎, 三木 祐司
    2016 年 102 巻 8 号 p. 443-450
    発行日: 2016年
    公開日: 2016/07/31
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    The effect of adding CaO-based desulfurization flux on desulfurization efficiency in hot metal desulfurization by mechanical stirring was investigated. It was found that desulfurization flux dispersion is enhanced by powder blasting with a carrier gas. In this research, the behaviors of the desulfurization powder under different blasting conditions were investigated, and the optimum blasting conditions for achieving higher desulfurization efficiency were examined. The velocities of the gas jet and particles were measured by pressure measurement by the pitot tube technique and LDV (Laser Doppler Velocimeter), respectively. The results showed that the powder velocity was accelerated by the gas jet, which agreed with the calculated velocity. The condition of powder penetration into the hot metal was examined based on the calculations. As a result, the higher carrier gas flow rate, 200 Nl/min, was categorized as a penetrating condition, and the lower carrier gas flow rate, 100 Nl/min, was not a penetrating condition. The difference in the desulfurization behaviors under those carrier gas flow rate conditions is caused by the difference in the penetrating condition. Based on the obtained blasting conditions, powder blasting tests were carried out in 300 t-scale hot metal desulfurization, and desulfurization flux consumption was decreased by 19% compared with conventional top addition.
加工・加工熱処理
論文
相変態・材料組織
論文
  • 奥田 金晴, 山光 一央, 貝沼 亮介
    2016 年 102 巻 8 号 p. 465-474
    発行日: 2016年
    公開日: 2016/07/31
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    The growth of the recrystallized nucleus in niobium added ultra-low carbon steel was investigated experimentally by restricting the nucleation sites. Moreover, the growth process of the recrystallized nucleus from the layered deformed microstructures with various deformed state were simulated by a multi-phase-field (MPF) method, for comparison with the experiments. The cold-rolled microstructure was a layered structure, consisting of both α-fiber close to cube orientation and γ-fiber, and the re-crystalline nucleus tended to grow up preferentially along deformed γ-fiber. The simulations suggested that the shape of growing nucleus was influenced by the dislocation density or layered distances of deformed structures, which were related to the cold-rolling reduction. Furthermore, the crystal rotation of the re-crystallized grains at the middle stage of recrystallization was tried to be simulated using another phase field simulation.
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