Coal Mine Gas Explosion Research Articles

Numerical Analysis on Propagation Characteristics and Safety Distance of Gas Explosiona

Through a roadway model with cross-section area of 80×80 mm2 and length of 100 m, the changing laws of overpressure, temperature, density, combustion rate and gas velocity after the explosion of methane-air mixtures with concentration of 9.5% and filling lengths of 2 m, 6 m, 10 m and 14 m were simulated by using AutoReaGas software. The results show that in the explosion propagation process, the peak overpressure firstly decreases, then increases, and then attenuates until to zero. However, flame propagation speed firstly increases, then begins to reduce and decreases until to zero. With the increase of methane filling length, the safety distance firstly increases and then decreases slightly, and the maximum distance of flame propagation increases linearly. With the increase of methane filling length, the initial peak overpressure and the maximum peak overpressure obviously increase, the peak overpressure and the maximum temperature in other points almost continually increase, and the distance where peak overpressure begins to rise and obtains its maximum value also increases. The time of flame arrival in the same point at various filling lengths is almost the same before flame speed begins to decrease, indicating that flame speed is almost the same before it decreases. Research results can be used to provide guidance for the safety of underground persons, the disaster relief and treatment of gas explosion in underground coal mines.

Theoretical Analysis on the Attenuation Characteristics of Strong Shock Wave of Gas Explosion

In order to study the propagation characteristics of strong shock wave, a theoretical analysis is performed in this paper. Based on some assumptions, the relationships of the peak overpressure and the gas velocity during a gas explosion with the propagation distance were derived by using the explosion and aerodynamics theory. The results show that the peak overpressure of a strong shock wave is inversely proportional to the propagation distance and the cross-section area of the roadway, but directly proportional to the total energy of the gas explosion. However, the gas velocity is inversely proportional to the square root of the propagation distance and the cross-section area, but directly proportional to the square root of the total energy of the gas explosion. According to these results, some preventive measures can be taken to reduce the loss caused by the gas explosions in underground coal mines.

Specific Statistics and Control Method Study on Unsafe Behavior in Chinese Coal Mines

Chinese coal mine safety situation has been very serious compared to other countries, and unsafe behavior is especially an important factor causing Chinese coal mine accidents. In this paper, it first through statistics finds that the proportion of gas explosion's death toll is the largest in the total death toll of Chinse coal mine accidents, and live-line work is the unsafe behavior causing the most death toll in Chinese coal mine gas explosion accidents. Then it gives a brief introduction and comparative analysis on the main behavior control methods at home and abroad – American DuPont company's STOP method, Japanese KYT method of Sumitomo Corporation, and domestic fine, hand pointing and oral description, safety education and training method, etc., and finds that each method has its own merits and faults. On this basis, combining the application of situation teaching and virtual reality in coal mines, two other unsafe behavior correction methods are proposed for Chinese coal mines: scenario design and virtual reality games. At the same time, it also suggests that we can first consider and choose live-line work - the unsafe behavior causing the most death toll in Chinese coal mine's primary accident of gas explosion, to design these two kinds of methods.

Statistical Analysis on Coal Mine Gas Explosion and Optimization of Safety Input

This paper statistically analyzes the large coal mine gas accidents in China since 2006, and points out that explosion and gas outburst are the main reasons of gas accident, and focus in the future should be put on those serious accidents caused by gas explosion. Death toll of large gas accidents in 2009 is equal to that in 2008, which illustrates the importance of safety input in order to further improve the coal mine safety situation in China. In order to raise consciousness of enterprises on safety input, this paper puts forward the idea of integrating the value of life casualties’ loss into the analysis of loss in coal mine accidents and builds an optimization model of optimization of safety input based on maximization of economic benefit and thorough analysis of safety input, economic losses caused by coal mine accidents and loss of human life. With reference to foreign practices and related research, the value of life for each person is finally set from 5 million to 30 million. Finally it is proved through case study that the consideration of value of life is vital to improve the level of safety input and reduce mortality. Since 2005, the number of deaths caused by gas accident many years occupied the first coal mine accident in major categories. Therefore, the gas accident occurred in recent year statistical analysis, to take specific measures for improving the level of China's coal mine safety is important.

Experiment study on the propagation laws of gas and coal dust explosion in coal mine

The experiment of gas and coal dust explosion propagation in a single laneway was carried out in a large experimental roadway that is nearly the same with actual environment and geometry conditions. In the experiment, the time when the gas and coal dust explosion flame reaches test points has a logarithmic function relation with the test point distances. The explosion flame propagation velocity rises rapidly in the foreside of the coal dust segment and comes down after that. The length of the flame area is about 2 times that of the original coal dust accumulation area. Shock wave pressure comes down to the rock bottom in the coal dust segment, then reaches the maximum peak rapidly and comes down. The theoretical basis of the research and assemble of across or explosion is supplied by the experiment conclusion. Compared with gas explosion, the force and destruction degree of gas and coal dust explosion is much larger.

Selective medium for MRSA.

<h3>Background</h3> Coal mine gas explosion injury has caused mass casualties, which have resulted in widespread concern. <h3>Methods</h3> In order to prevent gas explosion injury in coal mine, 24Model is proposed to analyse the risk in this paper. 24Model is a human-oriented and organisation-oriented risk analysis method. Based on the 24Model, we propose a general procedure for analysing the causes of injury within the organisation. <h3>Results</h3> A coal mine gas explosion case was analysed using the 24Model and the proposed analysis method, and the evolution of injury and the interaction of various causes was showed, and 6 unsafe conditions, 25 unsafe acts, 13 safety knowledge, 13 safety management systems and 13 safety cultures were obtained. <h3>Conclusion</h3> Case analysis results show that by using the 24Model and analysis method the proposed effect can help employees to clearly see the evolution and identify the causes of the injury, to better understand the logical relationship with the causes of the injury, improve the effectiveness of training and effectively prevent similar injury. The case study provides a practical procedure for injury investigation and analysis, and thus, preventive measures can be made according to the various causations at different levels.

Formation of free radicals in the RH + O 2 system: I. Tetralin, cyclohexanol, cyclohexanone

Gas explosion in coal mines caused a large number of deaths, injuries and property losses. Gas explosion still happens occasionally in recent years. It is known that most people died from CO poisoning in gas explosion. But the details of toxic gases produced and their impacts on people need further investigation. In order to study the products and species in gas explosion, an analysis of chemical kinetic characteristics was conducted using CHEMKIN III with detailed mechanism (GRI-Mech3.0) package. A closed homogeneous 0-D reactor was adopted to investigate the kinetic behavior of gas explosion. The initial conditions were set, similar to those in the real tunnel environment. The profiles of four reactants, toxic gases and free radicals were obtained. The threshold values of people exposed to different poisonous gases were analyzed to study their impacts on people. Sensitivity analysis of key elementary reaction to free radical was performed to find possible reactions which can suppress gas explosion. The results show that the ignition delay time is the longest at fuel-rich condition. The O2 concentration decreases from 19% to 2% at stoichiometric ratio, which could not support normal respiration after explosion. It is found that the concentration of CO ranks the highest among the four toxic gases. Toxicity analysis indicates that those exposed to such condition will soon die of asphyxia. This is consistent with the accident investigation findings that the majority of fatalities result from inhalation of CO. The concentration of CO at fuel-rich condition is higher than that at fuel-lean condition. The relationship between the final free radical concentration and initial CH4 concentration exhibits a reverse U shape. Sensitivity analysis reveals that free radicals are mostly sensitive to the intermediate reaction R156 (forward direction) and R158 (reverse direction). It provides a possible direction to research the corresponding chemicals for gas explosion suppression. This work would provide theoretical support for gas explosion suppression technology and decision-making of personal protection in rescuing trapped coal miners. It is of great importance for developing suppression chemicals of gas explosion.