一种煤粉着火的数学模型——(1)模型的建立

A Mathematical Model of Pulverized Coal Ignition(Ⅰ): Model Establishment

综合考虑影响煤粉气流着火的主要因素,基于锅炉中的能量平衡,建立了煤粉气流着火的数学分析模型.通过对煤粉气流着火的物理过程进行分析简化,引入燃烧器结构、煤种特性、运行工况等重要参数,推导出1个无量纲准则数Co来研究着火温度.结果表明:当Co增大时,煤粉气流的着火特性得到改善;为了使着火准则数Co增大,应减小煤粉粒径,调整燃烧器结构,提高烟气的回流率,并降低二次风率,延缓二次风与一次风的混合.

Based on energy balance in the boiler, a mathematical analysis model for ignition of pulverized coal stream was established by comprehensively considering about the main factors which effect the ignition of pulverized coal stream. Through analysis and simplification for the physical process of the ignition of pulverized coal stream, a dimensionless number Co, which was related to the structure of the burner, coal characteristic, operational condition and other important parameters, was developed to study the ignition point. Results show that with the increase of Co, the ignition of pulverized coal stream is improved. In order to increase the ignition Co, the diameter of the pulverized coal particle should be decreased, and burner structure should be adjusted, reflow ratio of flue gas should be improved. At the same time, the secondary air ratio of flue gas should be decreased, and combination of secondary air with primary air should be postphoned.