流化床燃烧超低浓度煤层气的轴向气体分布

Axial Gas Profile During Ultra-Low Concentration Coal Bed Methane Combustion in a Fluidized Bed

超低浓度煤层气由于甲烷含量低、浓度变化大而较难加以利用。采用实验和数值模拟的方法,研究了超低浓度煤层气在流化床中燃烧特性,得到燃烧产物的轴向分布规律,分析了进气浓度、床层温度、流化风速等因素对甲烷浓度轴向分布的影响。研究结果表明:随着床层高度的增加,无量纲甲烷浓度逐渐减小,在床层表面达到最小值,然后突然增加,随后达到稳定。实验范围内,CO浓度均小于20mL/m^3减小进气浓度、增加床层温度、降低流化风速部会使相同床层高度处的无量纲甲烷浓度减小。燃烧反应主要发生在密相区,随着进气浓度的减小、床层温度的增加、流化风速的降低,反应区域逐渐向床层下部移动。

The ultra-low concentration coal bed methane is difficult to utilize due to its low methane content and fluctuated concentration. The combustion characteristic of ultra-low concentration coal bed methane in a fluidized bed was studied experimentally and numerically. The axial profiles of combustion products were obtained. The effects of inlet methane concentration, bed temperature and fluidized velocity on axial profile were analyzed. The results show that the dimensionless methane concentration decreases with the bed height and reaches a minimum at the bed surface. Then, the value increases abruptly and goes steadily. The CO concentration is less than 20 mL/ma in all experiments. The dimensionless methane concentration at the same bed height decreases with decreasing inlet methane concentration, rising bed temperature and reducing fluidized velocity. Combustion mainly occurred in dense phase, and moved towards lower part of bed with decreasing inlet methane concentration, rising bed temperature and reducing fluidized velocity.