预热空气与高炉煤气的扩散燃烧混合特性研究

Study on Mixing Characteristics of Preheated Air and Blast Furnace Gas in Diffusion Combustion

针对某钢铁企业高炉煤气回收水冷系统的特点,分析研究了低热值高炉煤气与不同预热温度空气的同轴扩散气流在绝热炉膛内混合和燃烧的特点,据此建立k-ε双方程燃烧数学模型,并对其燃烧混合特性进行模拟研究。研究结果表明:回流中心区的位置位于轴向0.1~0.22 m,但随着空气预热温度的升高,缩小到0.12~0.2 m,回流负压也有所降低,同轴扩散气流在较低的空气预热温度下与管壁之间产生作用的范围更大;炉内气流的混合主要发生在炉膛的前半部分,空气预热温度越高,混合发生的位置越靠近气流入口。空气预热导致的热力作用有利于强化扩散气流内部之间及与回流气流之间的混合,缩短了火焰行程。这对优化低热值高炉煤气燃烧用炉膛结构提供了依据。

According to the characteristics of the water-cooling system for recovery of blast furnace gas in an iron and steel enterprise, the mixing and combustion characteristics of low calorific value blast furnace gas and the coaxial diffused air at different preheating temperatures in the adiabatic furnace were analyzed and studied.Based on this, the k-ε two-phase combustion mathematical model was established and the combustion mixing characteristics were simulated.The results show that the central reflux area is located within the axial range of 0.1~0.22 m.However, with the increase of air preheating temperature, the reflux negative pressure decreases to a certain extent, and the coaxial diffusion airflow has a larger interaction range with the pipe wall at a lower air preheating temperature.The mixing of the air flow in the furnace mainly occurs in the first half of the furnace.The higher the preheating temperature of the air, the closer the mixing occurs to the air flow inlet.The thermal effect caused by air preheating is beneficial to strengthen the mixing between the diffused airflow and the backflow airflow and shorten the flame travel.This provides a basis for optimizing the furnace structure of low calorific value blast furnace gas combustion.