工程科学学报2025，Vol.47Issue(8)：1602-1615,14.DOI:10.13374/j.issn2095-9389.2024.10.11.003
沉积煤尘卷扬诱发燃爆过程实验研究
Experimental study on the combustion and explosion process induced by the entrainment of deposited coal dust
摘要
Abstract
During the operation of pulverizing systems in power plants,high ambient temperatures create conditions in which coal dust deposited on equipment surfaces is prone to thermal runaway.When these self-ignited coal dust particles are lifted by airflow,there is a significant risk of combustion and explosion.To reveal the processes and mechanisms of dust cloud explosions induced by airflow entrainment,we constructed an experimental setup to monitor coal dust self-ignition,dispersion in a dust cloud,and the subsequent ignition and explosion.Next,we investigated the self-ignition process,characteristic parameters,critical conditions for entrainment-induced explosions,explosion behavior,and underlying mechanisms.The experimental procedure involved first placing the coal powder on a high-temperature flat plate and then using a high-pressure airflow to entrain the coal powder into the air under various spontaneous combustion conditions.Subsequently,the phenomena of spontaneous combustion,explosion,and their transitions were observed.The results indicated that thermal conduction and oxidative heat release were the primary causes of high-temperature spot migration during the self-ignition process of the deposited coal dust,with the high-temperature point moving upward from the hot surface and then downward.As the deposition thickness increased,both the peak temperature and the duration of the combustion propagation and decay stages increased,reaching 538℃,510℃,810 s,and 1520 s for thicknesses of 8 mm and 10 mm,respectively.The degree of self-ignition and the mass of coal dust significantly influenced the occurrence of explosions,with the central temperature representing the self-ignition level.When the central temperature of the coal dust layer ranged from 280℃to 420℃,the entrained coal dust could trigger an explosion.As the central temperature increased,the flame propagation speed first increased and then decreased,whereas the particle size and surface smoothness of the solid residue decreases.The flame propagation speed of the explosion was the largest(4.76 m·s-1)at a mass of 6.0 g and central temperature of 340℃.Additionally,the explosion intensity initially increased and then decreased with an increasing coal dust mass.Moreover,the maximum flame length and flame area occurred at 6.0 g,measuring 26.81 cm and 301.4 cm2,respectively.A lower dust mass resulted in insufficient combustible particles,leading to a decrease in flame intensity,whereas a higher dust mass limited combustion owing to an inadequate oxygen supply.Furthermore,the combined effects of the heterogeneous combustion of carbon particles and homogeneous combustion of volatiles,such as CO and H2,are the primary trigger mechanisms driving the explosion of deposited coal dust.The homogeneous combustion of combustible gases ignited the coal dust particles,thus further promoting the pyrolysis and combustion of coal dust,and producing more combustible gases and strengthening the explosion process.When coal dust has a low concentration and a low degree of spontaneous combustion,the combustion and explosions are dominated by heterogeneous combustion.Additionally,the coupling of these two ignition mechanisms leads to incomplete combustion,secondary ignition,and multiple ignition sources.This study provides a theoretical basis for the prevention and control of spontaneous combustion-induced explosion hazards in pulverized industrial systems.关键词
沉积煤尘/温度演化/煤尘云燃爆/火焰传播/诱发机制Key words
deposited coal dust/temperature evolution/coal dust cloud ignition/flame propagation/trigger mechanism分类
矿业与冶金引用本文复制引用
范晶,马砺,张鹏宇,张庆勇,石新慧..沉积煤尘卷扬诱发燃爆过程实验研究[J].工程科学学报,2025,47(8):1602-1615,14.基金项目
国家自然科学基金面上资助项目(5217042729) （5217042729）
