Study On Coal Dust Explosion Characteristics Change Law And Energy Propagation Model Of Different Metamorphism

The potential and destructiveness of different metamorphism coal dust explosions are very different,especially in coal mines where the environment is complex and changeable.In this paper,experimental method,theoretical analysis,mathematical modeling,and numerical simulation method are used to study the changes in the ignition sensitivity characteristics and strength characteristics of different coal dust explosions.Based on the theory of computational fluid dynamics,spatial distribution characteristics of coal dust explosion in horizontal pipeline is simulated.Based on dimensional analysis theory,coal dust explosion energy propagation model is established and an example is analyzed.In terms of ignition sensitivity characteristics of coal dust explosion,eight coal samples are used to test and analyze the minimum ignition temperature of coal dust cloud and coal dust layer and the minimum ignition energy of coal dust cloud.The influence of different coal particle diameters on the minimum ignition temperature of coal dust clouds and the effect of inert rock load on the ignition of coal dust clouds are discussed,and sensitive particle size intervals of coal dust cloud ignition are determined.The mechanism of the minimum ignition temperature change law of eight kinds of coal quality under different particle size and different dust layer thickness conditions are analyzed,and eight kinds of ignition types and ignition time under the conditions of the lowest ignition temperature are explored,and it is concluded that coal dust layer with small particle size and large thickness is more likely to catch fire.The correlation of coal dust priming temperature alienation under cloud and layered space conditions are revealed.Based on the study result of the minimum ignition energy change law of eight coal dust clouds,the coal dust cloud minimum ignition energy model of coal dust cloud mass concentration,ignition delay time,and dust injection pressure is established,and the coal dust cloud minimum ignition energy value and operating parameters are given.In terms of strength characteristics of coal dust explosion,four coal samples are used to test and analyze the maximum pressure of coal dust explosion,the maximum pressure rise rate,and the flame propagation characteristics.The variation law of the maximum explosion pressure and the maximum pressure rise rate of four kinds of coal under different dust pressure and ignition delay time is discussed.It reveals the propagation and evolution mechanism of four kinds of coal dust explosion flame flame peaks and the change law of flame length with time and space.It is considered that compared with lignite,long flame coal and non-stick coal have a shorter time to complete flame development.The relationship between the farthest propagation distance of the four types of coal dust explosion flame,the initial dust pressure,the ignition temperature,and the amount of rock mass mixed with anti-explosion rock is obtained.Lignite,long-flame coal,non-coking coal,and lean coal are selected to carry out flame characteristics experiment of deposited coal powder explosion induced by high-pressure airflow carrying coal dust.The relationship between the coal dust mass,sediment coal particle size,sedimentary rock powder content and maximum propagation distance and the flame duration of explosion flame ie obtained.And the flame duration of the explosion flame is considered to have greater impact than the effect of coal dust particle size on the joint explosion.Based on the theory of CFD,a horizontal pipe geometry model is constructed and the coal dust explosion flame temperature,the shock airflow and the toxic gas product propagation characteristics are simulated.By comparing the simulation result and the measured value,the reliability of simulation result is verified.Explosion area is divided according to distribution characteristics of flame temperature and shock airflow velocity at the time of sufficient reaction,which achieves reasonable and effective supplement to experimental research.Based on basic theory of the dimensional analysis,the "coal dust explosion energy factor" is defined,and the theoretical model between the explosion release energy and the time and the propagation distance of the explosion flame is established.After the model parameters rationality test and the exponent rationality test and the completeness test of the selected derived dimension,by the example analysis in the roadway space,the energy value of explosion and the participation mass of explosion coal dust under different conditions are calculated,which provide theoretical basis for disaster assessment.