O_2/N_2高温气氛下单颗粒煤焦反应行为特性数值模拟

Numerical Simulation of Single Coal Char Particle Reaction Behavior Characteristics in Hot O_2/N_2 Atmosphere

为探究煤焦颗粒反应行为特性,对高温O_2/N_2气氛中运动的单颗粒煤焦进行数值模拟研究。采用规则球形、不规则球形和多孔球形3种单颗粒煤焦结构模型耦合单颗粒煤焦反应模型,研究环境温度和O_2浓度对温度分布、组分分布和反应速率的影响。模拟结果与实验研究结果基本吻合,表明模型能有效描述单颗粒煤焦反应特性。结果表明,当环境温度升高,火焰层高温区域扩张但不发生迁移,碳消耗速率增大,颗粒内部CO_2摩尔分率降低,CO摩尔分率升高;当O_2浓度升高,火焰层高温区域扩张并向颗粒下方迁移,碳消耗速率近似线性增大,颗粒内部CO_2、CO摩尔分率均升高。

In order to explore the char particle reaction behavior characteristics, a numerical simulation study of single coal char particle moving in hot O2/N2 atmosphere was conducted. Adopting three different particle structural models： regular sphere, irregular sphere or porous sphere coupled with single coal char particle reaction model to investigate the effects of ambient temperature and oxygen concentration on temperature distribution, species distribution and reaction rate. The simulation results were consistent with the experimental results, and indicated model can effectively describe the single coal char particle reaction characteristics. The results show that when the ambient temperature increase, the high-temperature region of flame sheet expand but don＇t transfer, carbon consumption rate increase, CO2 mole fraction inside the particle decrease, CO mole fraction inside the particle increase. When the oxygen concentration increase, the high-temperature region of flame sheet expand and transfer to the below of the particle, carbon consumption rate increase almost linearly, CO2 and CO mole fraction inside the particle both increase.