Effects of temperature gradient and particle size on self ignition temperature of low rank coal excavated from inner Mongolia, China

This study investigates the effects of temperature gradient and coal particle size on the critical self-ignition temperature TCSIT of a coal pile packed with low-rank coal using the wire-mesh basket (WMB) test to estimate TCSIT based on the Frank–Kamenetskii equation. The values of TCSIT, the temperature gradient and the apparent activation energy of different coal pile volumes packed with coal particles of different sizes are measured. The supercriticality or subcriticality of the coal is assessed using a non-dimensional index IHR based on the temperature gradient at the temperature cross-point between coal and ambient temperatures for coal piles with various volumes and particle sizes. The critical value IHRC at the boundary between supercriticality and subcriticality is determined as a function of pile volume. The coal status of supercritical or subcritical can be separated by critical value of IHR function of pile volume. Quantitative effects of coal particle size on TCSIT of coal p...本研究采用丝网篮（wire-mesh basket, WMB）测试法，基于弗兰克-卡门涅茨基方程（Frank–Kamenetskii equation）估算临界自燃温度（critical self-ignition temperature, TCSIT），探究了温度梯度与煤粒粒径对装填低阶煤的煤堆临界自燃温度（TCSIT）的影响。研究测量了不同粒径煤粒装填的不同体积煤堆的TCSIT、温度梯度以及表观活化能数值。针对不同体积与粒径的煤堆，基于煤与环境温度的温度交叉点处的温度梯度，通过无量纲指数IHR（non-dimensional index IHR）评估煤样的超临界或亚临界状态。本研究确定了超临界与亚临界边界处的临界值IHRC，其为煤堆体积的函数。煤堆的超临界或亚临界状态可通过以煤堆体积为变量的IHR临界值进行划分。煤粒粒径对煤堆TCSIT的定量影响……