著者

Toshiyuki Hirosawa Akinori Murao Nobuyuki Oyama Shiro Watakabe Michitaka Sato

出版者

The Iron and Steel Institute of Japan

雑誌

ISIJ International (ISSN:09151559)

巻号頁・発行日

vol.55, no.6, pp.1321-1326, 2015-06-15 (Released:2015-06-20)

参考文献数

12

被引用文献数

4 6

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The use of high reactivity coke is a technology that dramatically improves the reaction efficiency in blast furnaces by decreasing the temperature of the thermal reserve zone. In this study, a blast furnace shaft simulator was developed to estimate the temperature of the thermal reserve zone and the distributions of the temperature and gas composition in the blast furnace when using cokes with different reactivity. The shaft simulator combines an experimental reaction furnace and a calculation model. Chemical reaction and mass/heat transfer phenomena in the blast furnace are considered in the calculation model so as to calculate the ore and coke reaction rate and the distribution of temperature and gas composition. Relatively small amounts of packed coke and sinter specimens are reacted with the temperature and gas composition controlled based on the calculation results. The coke gasification rate is fed back to the calculation model, and it is then possible to estimate the temperature of the thermal reserve zone and the distributions of the temperature and gas composition in the blast furnace. Shaft simulator experiments with high reactivity coke, such as CIC (Carbon Iron Composite), showed that the temperature of the thermal reserve zone is 140 K lower with high reactivity coke than with conventional coke.

著者

Kazuhira Ichikawa Yusuke Kashihara Nobuyuki Oyama Toshiyuki Hirosawa Jun Ishii Michitaka Sato Hidetoshi Matsuno

出版者

The Iron and Steel Institute of Japan

雑誌

ISIJ International (ISSN:09151559)

巻号頁・発行日

vol.57, no.2, pp.254-261, 2017-02-15 (Released:2017-02-16)

参考文献数

22

被引用文献数

11 14

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Recently, low coke rate blast furnace operation has been required in response to the rising cost of coking coal. However, the thickness of the coke layer decreases in low coke rate operation. Since it is known that the gas permeability of the blast furnace deteriorates as the coke layer thickness decreases, it is important to determine the minimum coke layer thickness for stable blast furnace operation. On the other hand, the minimum coke layer thickness has not been clarified due to a lack of equipment capable of measuring the effect of the coke layer thickness on permeability.In this study, a new experimental device called the cohesive zone simulator was developed to clarify the minimum coke layer thickness. In the cohesive zone, gas flows horizontally along the coke layer. In order to quantify the effect of the coke layer thickness on permeability, this horizontal gas flow should be simulated. Therefore, this simulator simulates a horizontal gas flow.Next, the effect of the coke layer thickness was quantified by using the cohesive zone simulator. The results showed that melting iron ore penetrated into the coke layer and closed part of the layer. These phenomena caused a deterioration of permeability under thin coke layer thickness conditions.Finally, a pressure drop estimation model considering penetration of the coke layer by melting ore was developed with the aim of quantifying the minimum coke slit thickness.

著者

Naoyuki Takeuchi Yuji Iwami Takahide Higuchi Koichi Nushiro Nobuyuki Oyama Michitaka Sato

出版者

The Iron and Steel Institute of Japan

雑誌

ISIJ International (ISSN:09151559)

巻号頁・発行日

vol.54, no.4, pp.791-800, 2014-04-15 (Released:2014-06-05)

参考文献数

31

被引用文献数

11 16

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In the recent operation of blast furnace, it is supposed that high gas permeability of burden is important for low RAR and high PCR operation. In this work, sinter quality for improvement in gas permeability of blast furnace was investigated with reduction degradation and under-load-reduction tests. As the results, the reduction degradation of sinter is deteriorated by increasing H2 concentration in the reduction gas under the condition of below 3.8 vol% H2. However, over 3.8 vol% H2, increase of H2 has no effect on the reduction degradation because the diffusion of reduction gas in the sinter is limited. On the other hand, from the under-load-reduction test, there is possibility that increase in H2 concentration of reduction gas and decrease in slag ratio in sinter are effective to improve gas permeability of lower part of blast furnace rather than reducibility of sinter. Due to adoption of these experimental results to a 2-dimentional mathematical simulation model, the precision of pressure drop calculation of blast furnace was improved. It is considered from the evaluation by this model calculation that the RDI, a slag ratio and the slag viscosity as the sinter properties are greatly influence on the permeability of blast furnace.

著者

Tatsuro Ariyama Michitaka Sato Taihei Nouchi Koichi Takahashi

出版者

The Iron and Steel Institute of Japan

雑誌

ISIJ International (ISSN:09151559)

巻号頁・発行日

vol.56, no.10, pp.1681-1696, 2016-10-15 (Released:2016-10-15)

参考文献数

59

被引用文献数

4 46

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Blast furnace has been regarded as a highly optimized process as a result of various technological improvements over its long history. However, from the viewpoints of resources, energy and global warming, continuing evolution toward reductant flexibility and CO2 mitigation is desired. This review focuses on the progressive design of an ambitious blast furnace for the future.First, the history of techniques for reducing coke rate and reducing agent in the blast furnace are reviewed. Pulverized coal injection is currently common; however a more innovative process is desired in order to address the global warming issue. The low temperature blast furnace based on charging of high reactivity coke is a realistic process. The combination of the oxygen blast furnace with top gas recycling is also attractive. Although the top gas recycling process based on the oxygen blast furnace is very effective for reducing CO2 emissions, a total evaluation considering the role of the blast furnace to keep the energy self-sufficiency in the integrated steel works is necessary. The oxygen blast furnace enables injection of a large amount of natural gas, and optimized injection of natural gas and pulverized coal makes it possible to mitigate CO2 emissions while maintaining the energy supply to downstream processes. Moreover, owing to the high productivity of the oxygen blast furnace, the blast furnace profile can be downsized. The characteristics of several processes are quantitatively examined, and the concept of the advanced oxygen blast furnace as a next-generation process toward carbon dioxide mitigation is discussed.