Effect of Oxygen Concentration on the Oxidative Thermodynamics and Spontaneous Combustion of Pulverized Coal

Abstract

Spontaneous combustion of pulverized coal has become a safety topic and has been extensively researched. This study using differential scanning calorimetry investigated the exothermic characteristics and spontaneous combustion risk of three metamorphic pulverized coal samples during oxidative combustion, for oxygen concentrations of 21, 19, 17, 15, 13, 11, 9, 7, and 5 vol %. Results indicated that decreased oxygen concentrations reduced exothermic intensity and substantially increased ignition temperatures. The oxidative thermal release observed during the combustion stage was conspicuously higher than during the low-temperature oxidation stage. Thermal release during low-temperature oxidation was low during low oxygen concentrations; however, when the oxygen concentration was less than 13.0 vol.%, it had a considerable influence on exothermic combustion. When the oxygen level was lowered from 21.0 to 5.0 vol %, spontaneous combustion risk indexes lessened from 2.07 (sample A), 1.85 (sample B), and 0.81 [J/(mg min °C2 )] (sample C) to 1.08 (sample A), 1.13 (sample B), and 0.40 [J/(mg min °C2 )] (sample C), respectively. Both apparent activation energy and spontaneous combustion risk indexes of the samples decreased saliently as oxygen concentration decreased. Thus, reducing oxygen concentration would be an effective method of inhibiting or possibly even preventing the spontaneous combustion of pulverized coal.

Inhibition of Spontaneous Combustion Characteristic of Biomass Treated with Imidazolium-Based Ionic Liquids Using Thermogravimetric Analysis

“…With untreated biomass having a volatile matter content of 60.52%, the sample is highly likely to be more reactive and easily combustible. As seen from Table , biomass also possesses high oxygen concentration which leads to an increase in the self-ignition attribute of fuels and their SPONCOM liability according to Huangfu et al and Ren et al Furthermore, it can be also seen from Table that biomass is low-quality fuel, given that it had a low calorific value of 17.28 MJ/kg.…”

Analysis of the Single Coal Particle Combustion Process under O2/CO2 Atmosphere Based on Spectral Diagnostics Technology: Combination of Spectroscopic Characteristics and Flame Temperature

“…In addition, experiments studied the effects of various parameters, such as coal type, particle size, heating rate, ambient temperature, and gas composition for the single coal particle flames. In particular, Ren predicted the effect of oxygen content on spontaneous pulverized coal combustion, and the results indicated that the ignition temperature substantially increases with the decrease of oxygen concentration and exothermic intensity. Saha , studied the effect of the oxygen concentration and turbulence state on the combustion characteristics of pulverized brown coal with moderate or intense low oxygen dilution (MILD) combustion conditions using experimental and numerical simulation methods.…”