Experimental Study On Law Of Oxygen Entrainment In High Temperature Loose Coal

Coal spontaneous combustion seriously affect the safety of China's coal industry. Studies have shown that oxygen supply have a significant impact on the development of coal fire, and the transporting of oxygen in loose coal is mainly affected by: the fissure field and dynamic source. Air leakage and oxygen entrainment in the loose coal is the dynamic source that promoting oxygen transporting. However the study of oxygen transporting mostly focus on the air leakage, and the mechanism of oxygen entrainment in loose coal is still unclear.Based on the theoretical analysis of air flowing dynamics and resistance in loose coal,the buoyancy caused by changes of air density is the main dynamics of oxygen entrainment.And using a new experimental device which was build in order to study oxygen entrainment in loose coal,carried out a series of experimental studies,when the temperature of heat reourse is 30?, 60?, 90?, 120?, 150?, 200?,and analyzed the different of temperature distribution in loose coal while the porosity changes. Geted the law of temperature distribution around the heat source in loose coal,heat transfer is easier in loose coal under big porosity. we found that the heat source have a greater impact on temperature in loose coal,when the heat source is located below it.And studied the buoyancy in loose coal, using the temperature data collected from the experiment. The results show that the buoyancy in loose coal increases with the increasing of heat temperature.The factor effecting buoyancy changes as the location of heat source moving away. Nearby the heat source buoyancy mostly effected by the temperature,and as the distance increases the buoyancy is biger in large porosity loose coal region, under the same temperature. And the buoyancy in loose coal decrescent as the distance increases away from the heat source.Finally,using the ANSYS software builded a model which is same as the experimental device in size. Then studied the process of oxygen entrainment under different temperature, different porosity and different position of heat source. The law of gas flow in loose coal near heat source was concluded, and proved the reasonable of experimental results.The farther away from the heat source the lower of velocity. When the temperature is constant the velocity of air is proportional to the porosity,however the porosity of loose coal has small impact on the gas pressure. The smaller angle of experimental device the biger of the buoyancy force, the easier development of the oxygen entrainment under the same conditions.