Experimental Study On Visualization Simulation Of Coal Spontaneous Combustion Evolution In Goaf

The spontaneous combustion of coal in the goaf is one of the disasters that often occur during the coal mining process,which not only seriously threatens the life safety of underground workers,but also causes serious waste of resources and property losses.The study of the occurrence and development of coal spontaneous combustion plays a key role in the prevention of mine fires.The development process of coal spontaneous combustion is the result of multiple physical and chemical interactions.The structure and composition of coal itself are extremely complex and heterogeneous,and its molecular composition cannot be accurately described from a chemical perspective.In summary,it is difficult to infer theoretically.Perform its spontaneous combustion process.At present,most of the domestic and foreign researches on the change of the temperature distribution of the goaf are numerical simulation methods or simulation experimental devices.Based on previous research,this article proposes an experimental device and method that can intuitively and quickly reflect the evolution of the spontaneous combustion of coal in a goaf under laboratory conditions,and the temperature distribution in the goaf,and Change the ventilation intensity and the change rule under the ventilation mode,use infrared thermal image analyzer to realize the temperature field visualization,and provide good experimental conditions for exploring the spontaneous combustion danger area of the goaf.The main body of this test is composed of the equivalent model of the goaf,the air inlet pipeline,the ultrasonic oscillating wave water mist generator,the fan,and the infrared monitoring system.The equivalent body of the goaf is a hollow cube,filled with high purity and high activity.Calcium oxide particles for laboratory use.The test principle is: the spontaneous combustion of coal is essentially the process of coal generating heat with oxygen and accumulating heat.In the test,the characteristic of calcium oxide reacting with water mist to generate heat is used to simulate the oxidative heat generation process of coal remaining in the goaf.The heat generation rate of water mist is greater than the coal-oxygen reaction,thereby achieving rapid reflection of temperature changes in the goaf;the filling of calcium oxide particles with different particle sizes in the equivalent body of the goaf,simulating the accumulation of coal remaining in the goaf;Under certain conditions,the amount of heat generated by calcium oxide is greater than the heat carried away by the air current,and the temperature of calcium oxide rises.Dividing the temperature rise area can guide the determination of spontaneous combustion danger areas in the goaf.The temperature field observation instrument is a handheld infrared camera,which realizes the intuitive reflection of the temperature change process in the goaf.The experiment mainly includes the following: under the condition of "U" type ventilation,the temperature field evolution process is observed in real time,and the infrared images taken at regular intervals are exported and analyzed.The results show that the heat dissipation belt is distributed near the air inlet and the air return,and gradually Later it is stable until the width of the heat radiation zone on the inlet side is larger than that on the return air side.The oxidizing temperature rise zone has a “shorn shape” distribution;if other conditions are not changed,adjust the amount of air volume,observe the change of the temperature field,and analyze the air volume on the goaf.The effect of the "three-zone" distribution shows that the air volume increases and the width of the heat dissipation zone increases,that is,the oxidized temperature rise zone moves backward;the above research is repeated under the "U + L" ventilation mode,and the results show that the temperature range of "U + L" ventilation is larger than that of "U" ventilation,and the temperature rising trend near the link lane is obvious.Finally,the comsol software was used to establish a goaf model to simulate the temperature field distribution in the goaf.The cooling area on the inlet side was larger,while the high-temperature area was closer to the working face on the return side,further verifying the correctness of the experimental results.