Study On Infrared Visualization Of Simulating Coal Oxidation And Heating Process In Goaf With Different Ventilation Modes

According to statistics on coal mine accidents across the country from 2010 to2020,the average number of deaths per accident in mine fires ranks first among all types of accidents in coal mines.In the future,as mining depths increase,the problem of spontaneous combustion in mines seams will also increase.In view of the serious consequences of mine fire accidents,the goaf is the most common place of fire in coal seams Therefore,studying the law of spontaneous combustion of the remaining coal in the goaf is helpful to provide guidance for fire prevention and improve mine safety.At present,the monitoring methods and methods of the goaf on-site haven’t obtained essential breakthrough development,and it’s difficult to obtain on-site parameters of the goaf.Therefore,the article has built a similar simulation experiment platform to simulate the oxidation and heating process of the remaining coal in the goaf.,To realize the study of the regional law of the spontaneous combustion hazard of the goaf.Based on the spatial characteristics and air leakage characteristics of the goaf,the thesis completed the laboratory goaf model with a geometric similarity ratio of 1:300under the guidance of similarity theory.It is proved that the flow field of the goaf is similar to the actual goaf when the wind velocity at the working face is greater than0.759m/s.The experimental model for simulating the oxidation and heating process of the remaining coal in the goaf includes the four major components of the goaf model box,the similar material filling system,the ventilation system,and the temperature monitoring system.The similarity of calcium oxide,which is a similar material,has been demonstrated,which proves that the relevant experimental rules obtained from the model test are effectively applicable to the goaf prototype.According to the experimental plan,the simulation of the temperature field under three different wind speeds of 0.8m/s,1.0m/s and 1.2m/s under the three ventilation modes of "U","W" and "Z" was completed.Infrared thermal imaging camera was used to record the temperature distribution state of calcium oxide in the goaf model during the experiment,and the law analysis of infrared images was completed through the combination of Samrt View software and Image-Pro Plus software.Under the "U" and "W" ventilation modes,the increase in the wind speed of the working face in the goaf has both advantages and disadvantages on the risk of spontaneous combustion of the residual coal in the goaf.The risk of spontaneous combustion is reduced.On the other hand,the risk of spontaneous combustion in the deep part of the goaf is increased.Under the "Z" type ventilation method,the wind speed of the working face in the goaf is increased,the area of the low temperature area close to the vent is slightly increased,and the area of the high temperature section area is greatly reduced.The increase in wind speed at the working face will help reduce the risk of spontaneous combustion in the goaf.The shape of the temperature rise area is different under different ventilation methods.The shape of the temperature rise area is different under different ventilation methods.The temperature rise area in the "U" type ventilation method presents a "moon" shape,and the temperature rise area in the "W" type ventilation method presents a nearly symmetrical "double moon" shape.The temperature rise area is distributed in two areas far away from the air inlet and the air outlet in the "Z" type ventilation mode.