Two Dimensional Cold Model Study on Unstable Solid Descending Motion and Control in Blast Furnace Operation with Low Reducing Agent Rate
Two Dimensional Cold Model Study on Unstable Solid Descending Motion and Control in Blast Furnace Operation with Low Reducing Agent Rate
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DOI：
10.2355/isijinternational.45.1386
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发表时间：
2005
影响因子：
1.8
通讯作者：
Hiroshi Takahashi;H. Kawai;Motofumi Kobayashi;T. Fukui
中科院分区：
文献类型：
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作者：
Hiroshi Takahashi;H. Kawai;Motofumi Kobayashi;T. Fukui
使用二维冷模型模拟了高炉低还原剂用量操作中固体床架桥/滑移的不稳定行为。氧化铝球用作焦炭/矿石填充床的代表颗粒。对两种透气性不同的死亡颗粒进行了检测。为了模拟粘性带对非定常行为的影响，在床层顶部充填了一定厚度的透气性较低的砂层，当砂层到达下部时，以粘性带的形式下降。此外，假设细粉堆积，在竖井底部设置一定尺寸的细焦层。假设在较低还原剂用量操作中透气阻力增加，则在竖井中装填的另一薄砂层中观察到细焦炭堆积的不稳定现象。结果表明，外围流量与总注气量之比对固体下降运动和气体静压的不连续行为有相当大的影响。该比率随着安全装置透气性的下降、模拟粘性区接近安全装置表面以及小颗粒流入滚道而增加。模拟内聚区存在一个不连续性快速增加的最低临界位置。细粒堆积时的桥接/滑动行为受到竖井中填充的低透气层的显着影响。在中心部位设置高透气性烟囱区，可有效减少不连续运动。
Unsteady behavior with bridging/slipping of solid bed in low reducing agents rate operation of blast furnace was simulated using a two dimensional cold model. Alumina sphere was used as representative particle of coke/ore packed bed. Two kinds of deadman particles different in gas permeability was examined. To simulate the effect of cohesive zone on unsteady behavior, a sand layer of lower gas-permeability was charged with a certain thickness at the top of the bed, which descended with a form of cohesive zone when it reached at the lower part. Further, a fine coke layer was set at the shaft bottom with a certain size assuming accumulation of fines. Unsteady phenomenon with the fine coke accumulation was observed with another thin sand layers, charged in the shaft assuming increase of gas-permeability resistance in lower reducing agents rate operation. It was revealed that the ratio of peripheral flow rate to the total gas injection rate had a considerable effect on the discontinuous behavior of both solid descending motion and gas static pressure. The ratio increased with decline in deadman gas-permeability, approach of the simulated cohesive zone to deadman surface and inflow of small particles into raceway. There was a lowest critical position of the simulated cohesive zone for the rapid increase of discontinuity. The bridging/slipping behavior with fines accumulation was significantly affected by the low gas-permeability layers charged in shaft. Setting up the chimney zone of high gas-permeability at the central part was effective to decrease the discontinuous motion.