熔融气化炉风口回旋区冶炼特征的数值模拟研究

相比于高炉风口喷吹富氧热风，熔融气化炉风口采用常温纯氧，使得炉内质量、动量、热量的传输以及煤气流分布等冶炼特征与高炉存在较大差异.通过建立熔融气化炉风口回旋区二维数学模型，系统考察熔融气化炉风口回旋区内速度分布、温度分布及气体组分分布的冶炼特征.结果表明:在气固相热交换及焦炭 (或块煤形成的半焦) 燃烧反应的综合作用下，熔融气化炉风口回旋区内气体温度迅速升高至3 500 K以上；此外，风口前端存在小规模的气体循环流动现象，故风口前端扩孔破损现象严重，进而导致非计划休风率较高；为减少此类休风现象，可适当额外喷吹富氢燃料性气体 (天然气、焦炉煤气)，不仅能降低风口回旋区内气体温度，更可替代部分固体燃料，并充分发挥其中H₂的高温还原优势，提升熔融气化炉冶炼效率. 

Numerical simulation of smelting characteristics around raceway in melter gasifier

In comparison with blast furnace, pure oxygen instead of air is injected into melter gasifier. Thus, there is a great difference between melter gasifier and blast furnace in the mass, momentum, heat transfer and gas distribution. A two-dimensional mathematical model at steady state was developed to describe the gas velocity, temperature and species distribution around raceway in melter gasifier. The results show that the gas temperature reaches above 3 500 K rapidly, due to the heat exchange with the burden and the heat release of combustion reaction with coke or semi-coke formed by lump coal. In addition, a small-scale gas circulation flow phenomenon is observed in front of tuyere. Thus, there is a serious damage in the front of tuyere which results in a higher unplanned blowing-down percentage. In order to decrease the gas temperature in the raceway to prevent the blowing-down, the appropriate hydrogen-rich fuel gas, including natural gas, coke oven gas, can be fed through the tuyere. Furthermore, it also reduces the solid fuel ratio and improves the reduction advantage of H₂ in the high temperature to enhance the smelting efficiency of melter gasifier.