直接还原铁对高炉冶炼指标影响规律
Effects of direct reduced iron on blast furnace smelting indexes
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摘要: 为应对碳减排与铁矿石资源约束等问题,通过建立高炉添加直接还原铁(direct reduced iron,DRI)的能质平衡模型,研究了直接还原铁对高炉理论燃烧温度、炉腹煤气指数及利用系数等关键冶炼指标的影响规律。结果表明,额外大量添加直接还原铁冶炼易导致高炉热量不足。以全炉热损失不低于基准工况的80%为约束,直接还原铁的极限添加量(质量分数)为2.6%;进一步降低直接还原铁金属化率,将加剧全炉热支出。在维持热损失与基准条件一致的前提下,提高风温和富氧率后适宜的直接还原铁添加量几乎一致,虽然提高喷煤量后适宜的添加量大幅增加,但高炉理论燃烧温度和炉腹煤气指数劣化严重。提高风温与富氧率对热补偿的效果基本一致且可相互替代,能缓解喷煤带来的理论燃烧温度下降等问题。在综合热补偿措施下,直接还原铁最高添加量(质量分数)达到了12.12%,吨铁碳素消耗降低了56 kg。Abstract: To address the challenges of carbon emission reduction and iron ore resource constraints, the influence of direct reduced iron (DRI) on the key smelting indexes such as theoretical combustion temperature, bosh gas index and productivity coefficient of blast furnace was studied by establishing the energy and mass balance model of adding DRI to blast furnace. The results indicate that adding a significant amount of DRI easily leads to insufficient heat of blast furnace. Constraining the total heat loss of the blast furnace to no less than 80% of the base case, the maximum DRI addition is 2.6%. A further decrease in the metallization rate of the DRI would exacerbate the total heat expenditure of the blast furnace. Under the premise of maintaining the heat loss consistent with the base case, the suitable amount of DRI that could be added is almost the same after either increasing the blast temperature or the oxygen enrichment ratio. Although increasing the pulverized coal significantly increases the suitable DRI amount, the theoretical combustion temperature and bosh gas volume index of blast furnace are seriously deteriorated. Increasing the blast temperature or oxygen enrichment ratio on thermal compensation is basically the same and can be replaced by each other, and problems such as the decrease in theoretical combustion temperature caused by pulverized coal injection are alleviated. Under comprehensive thermal compensation measures, the maximum DRI addition reaches 12.12%, and the carbon consumption per ton of hot metal decreases by 56 kg.
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