Rapid Contrastive Experimental Study on the Adiabatic Spontaneous Combustion Period of Loose Lignite

Abstract

The adiabatic spontaneous combustion period of coal is an important index for the macroscopic characterization of coal spontaneous combustion, and it is affected by many internal and external factors. There are several methods to study it, but there are various shortcomings to these methods. Some require too much time, while others have too many interfering factors. To quickly obtain the accurate adiabatic spontaneous combustion period of coal, a rapid contrastive experimental method was designed. In this method, the coal samples of the experimental and control groups were the same, and air and nitrogen were used as control atmospheres. A theoretical calculation method for the adiabatic spontaneous combustion period based on this method is proposed. The experimental results showed that during the temperature-programmed coal spontaneous combustion experiment, the increase in the coal temperature was due to physical and chemical heating. Physical heating is the heating effect of the temperature-programmed furnace body and the heated gas on the coal sample. Chemical heating includes oxidative exothermic heating promoted by physical and adiabatic oxidation heating. The adiabatic oxidative heat release can be determined by the oxidation heat release in the air atmosphere minus the oxidation heat release corresponding to the coal sample temperature in the nitrogen environment at the same period. The adiabatic spontaneous combustion period of coal can be calculated from the adiabatic oxidation heat release. Our results provide a rapid contrastive experimental method to quickly obtain the accurate adiabatic spontaneous combustion period of coal.

Experimental Study on Spontaneous Combustion Characteristics of Large Coal Particles after Soaking

“…The samples of lignite in this experiment were obtained from the Fengshuigou Coal Mine of the Pingzhuang Coal Company in Inner Mongolia, China. The process of coal sample crushing preparation is the same as refs ( 7 ) and ( 16 ), and crushing and soaking are shown in Figure 10 , the water used for soaking is distilled water.…”

“… 2 , 3 This significantly affects and restricts the safe production of coal mines, threatens the lives and health of miners and causes greenhouse gas emissions and environmental pollution. 4 − 7 In addition, CSC also burns large amounts of coal resources and indirectly causes the destruction of surface vegetation, soil desertification, surface collapse, and disorderly discharge of dust particles. Thus, they have become a serious international environmental disaster.…”

“…Coal mine fires are one of the most serious disasters faced by the coal industry all over the world, where coal is mined using the underground method. Take China, for example, more than 90% of the coal mine fires are caused by CSC. , This significantly affects and restricts the safe production of coal mines, threatens the lives and health of miners and causes greenhouse gas emissions and environmental pollution. − In addition, CSC also burns large amounts of coal resources and indirectly causes the destruction of surface vegetation, soil desertification, surface collapse, and disorderly discharge of dust particles. Thus, they have become a serious international environmental disaster. − Water mainly affects coal spontaneous combustion by altering the physical and chemical structures of coal and changing the characteristics and processes of coal spontaneous combustion.…”

Study on the Coal-Oxygen Intrinsic Reaction at Low Temperature by the Subtraction Method

“…Adiabatic oxidation and temperature-programmed methods are currently used mainly to investigate the spontaneous combustion characteristics of coal. − Owing to the fact that the adiabatic oxidation method requires more coal samples and has a longer experimental cycle, the temperature-programmed method has been more widely used in studying the spontaneous combustion characteristics of coal. Xu et al investigated the characteristics of spontaneous heating and temperature rise, oxygen consumption rate, and gas product characteristics of CO/CO 2 in the temperature-programmed oxidation process of lignite from the Beizao coal mine.…”

Influence of Long-Term Immersion in Water at Different Temperatures on Spontaneous Combustion Characteristics of Coal

“…Spontaneous combustion of coal (SCC) is a widespread problem worldwide − that has evolved from a safety production problem into a serious international environmental disaster. − The depths have gradually increased in recent years, the high temperatures (HT), high stresses (HS), high water contents (HW), high gas contents (HG), and thermodynamic disasters of these mines are serious and prominent . SCC in goaf areas is one of the main problems of thermodynamic disasters due to the increase of the coal and rock temperature, the increase of the SCC heating rate, the shortening of the time required for oxidation, the intensification of the risk of spontaneous combustion of coal (RSCC) in the goaf, and the difficulty of combustion prevention and control. , According to preliminary statistics, the maximum mining depth of the Heim mine in the Ruhr area of Germany is 1480 m, and the temperature of coal rock is as high as 68–70 °C; In China, in some coal mines below 800 m, the temperature of coal exceeds 45 °C and even reaches 50 °C .…”