高炉下部气固湍流和煤粉燃烧的数值模拟与优化研究

高炉喷吹煤粉时,由于煤粉的不完全燃烧,在回旋区处会产生未燃煤粉,影响高炉的透气性。建立了气固两相湍流和煤粉燃烧的三维数学模型,并且验证了该模型的可靠性。用所建模型对由直吹管、风口、回旋区和焦炭床构成的高炉下部区域进行了喷吹煤粉流动与燃烧现象的模拟研究。模拟结果揭示了高炉炉内气固流动和煤粉燃烧的基本性质和特点;通过正交试验方法研究不同操作因素对评价指标煤粉燃尽率的影响,得到4个操作因素对燃尽率的影响程度依次分别为喷煤量、富氧率、鼓风量和鼓风温度。而工况(喷煤量1 25kg/t,鼓风量1 950m3/min,鼓风温度1 523K,富氧率5.0%)为最佳优化工况,可实现提高喷煤量和煤粉燃尽率的效果。

Numerical simulation and optimization of gas-particle turbulent flow and pulverized coal combustion in the lower zone of blast furnace

In the condition of high rate of pulverized coal injection, incomplete combustion of partial pulverized coal will take place and unburned coal appears and accumulates in blast furnace, which affects the permeability of burden column. In order to analyze turbulent gas-particle two-phase flow and pulverized coal combustion process in the raceway of blast furnace more accurately, a three-dimensional mathematical model of gas-particle turbulent flow and pulverized coal combustion is formulated, and the model is validated. The model is applied to simulate in-furnace phenomena in terms of flow and combustion of pulverized coal injection for the whole region of blow pipe-tuyere-raceway-surrounding coke bed in the lower zone of blast furnace. The results reveal infurnace characteristics of gas-particle flow and pulverized coal combustion. The effects of different operating factors on pulverized coal burn-out are studied with orthogonal test method. It indicates that the order of four factors on the burn-out evaluation is ranked as pulverized coal injection rate, oxygen enrichment, blast volume and blast temperature. The best conditions to increase pulverized coal injection rate and coal burnout are determined as follows： pulverized coal injection rate 125 kg/t, blast volume 1 950 m3/ rain, blast temperature 1 523 K and oxygen enrichment 5.0 %.