高炉炼铁煤焦置换新概念

New concept about replacement ratio between coke and coal

煤焦置换比是衡量喷煤效果的重要指标,在一定冶炼条件下,置换比与喷煤量的关系遵循递减规律,如何优化高炉操作提高煤焦置换比是高炉炼铁的重要工作之一。为了明确置换比的可调控因素,首先通过对比分析实际置换比和理论置换比的计算方法,确定了高炉喷煤置换比与入炉焦炭成分、煤粉性能和煤粉在高炉内行为之间的数学关系。其次通过统计分析焦比和置换比随着煤比的变化关系,发现焦比随着煤比的变化存在一个拐点,拐点之后焦比降低程度减小,表明置换比开始显著降低。焦比拐点和置换比显著降低开始点是表征置换比稳定区的重要指标,延迟拐点位置是高炉炼铁节能降耗、降本增益必须关注的问题。影响喷煤置换比的主要因素包括3个方面:喷吹煤粉特性、高炉操作以及实际喷煤量。改善置换比的主要措施包括3个方面:提高燃料的燃烧性、保持合理的炉料分布以及改善原燃料质量。

The replacement ratio between coke and coal is a key index to evaluate the performance of pulverized coal injection technology.However it decreases with the increasing of coal ratio.It is a key task for blast furnace ironmaking to keep a high replacement ratio.In order to explicit the factors influencing the replacement ratio,the mathematical computation process of actual replacement ratio and theoretical replacement ratio were analyzed first,while the relationship of replacement ratio to coke compositions,coal properties and coal behavior in blast furnace were determined.There is an inflection point in the evolution process of coal ratio changing with coal ratio by statistic analysis of the correlation between coke ratio and coal ratio.Coke ratio decreases slowly after the inflection point,which indicates that the replacement ratio decreases.The inflection point of coke ratio means the starting point when replacement ratio decreases greatly.It is an important concern to delay the inflection point in order to achieve energy-saving,emission-reduction,low-cost and high-profit ironmaking.The main factors influencing the replacement ratio include characteristics of pulverized coal,operation of blast furnace and the amount of injected coal.Thus,in order to improve the replacement ratio,better combustibility of coal,proper burden distribution and enhanced quality of raw materials are required for the blast furnace ironmaking.