Studies on accidental gas and dust explosions

气体与粉尘意外爆炸研究

Fire Safety Journal, In press, corrected proof, Available online 9 May 2017

Ritsu Dobashi

Abstract：Fires and explosions are the disasters caused by uncontrolled combustion phenomena. The flame propagation during gas and dust explosions is much faster than the flame spread during fire. Therefore, the serious damages by accidental explosions often expand widely in a very short time. In this paper, the gas and dust explosions are described from a viewpoint of flame propagation phenomena. The understanding of flame propagation phenomena is indispensable to perform the consequent analysis of accidental explosions. Basic matters and recent research results on the flame propagation during gas and dust explosions are explained.

Methane-induced explosions in vented enclosures

排风柜中甲烷诱发的爆炸

Journal of Loss Prevention in the Process Industries, Volume 48, July 2017, Pages 199-206

Hayri Sezer, Francis Kronz, V'yacheslav Akkerman, Ali S. Rangwala

Abstract:Explosions in enclosures leading to devastating accidents occur in various industrial, commercial, and residential occupancies. To relieve the effect of such explosions, vents of various sizes and geometry are designed. In this study, a computational model for gas explosions venting, developed and validated on hydrogen explosion by Ugarte et al. [Process Safety and Environmental Protection, 99, (2016) 167–174] is extended to vented explosion scenarios for methane. The model is based on a time-dependent set of ordinary differential equations whose solution allows prediction of temperature, pressure and vented mass transients resulting from the explosion of methane-air in vented enclosures. The model is compared to the experiments available in the literature and NFPA 68 standards at different vent areas and equivalent ratios. The influence of gas equivalence ratio and vent size on the rate of pressure rise is analyzed. A framework for the gas explosion vent design using the fundamental laminar burning velocity of a gas-air mixture is also discussed.

Simplified function of indoor gas explosion in residential buildings

住宅建筑室内气体爆炸约简函数

Fire Safety Journal, Volume 87, January 2017, Pages 1-9

T. Chyży, M. Mackiewicz

Abstract：An original function describing the occurrence of indoor gas explosion in residential buildings has been presented in the paper. The function has been developed in order to simplify the description of explosion occurrence with its principal parameters, pressure and dynamics, being retained. It is a self-adaptative function, which means that its time function depends on the condition of construction elements, mainly decompressing areas called vents. The function consists of two parts. One is the phase of explosion pressure increase and the second is the decompression phase described by the fvent. modifier. The multiplication of the explosion pressure increase function and the fvent. modifier provides a final description of a pressure function for a vented explosion. The proposed function dependence enables an efficient dynamic analysis of three-dimensional models of building structures by means of the FEM.

Fast and safe gas detection from underground coal fire by drone fly over

无人机探测地下煤火瓦斯的快速安全方法

Environmental Pollution, Volume 229, October 2017, Pages 139-145

Lucila Dunnington, Masami Nakagawa

Abstract:Underground coal fires start naturally or as a result of human activities. Besides burning away the important non-renewable energy resource and causing financial losses, burning coal seams emit carbon dioxide, carbon monoxide, sulfur oxide and methane, and is a leading cause of smog, acid rain, global warming, and air toxins. In the U.S. alone, the combined cost of coal-fire remediation projects that have been completed, budgeted, or projected by the U.S. Department of the Interior's Office of Surface Mining Remediation and Enforcement (OSM), exceeds $1 billion. It is estimated that these fires generate as much as 3% of the world's annual carbon dioxide emissions and consume as much as 5% of its minable coal. Considering the magnitude of environmental impact and economic loss caused by burning underground coal seams, we have developed a new, safe, reliable surface measurement of coal fire gases to assess the nature of underground coal fires. We use a drone mounted with gas sensors. Drone collected gas concentration data provides a safe alternative for evaluating the rank of a burning coal seam. In this study, a new method of determining coal rank by gas ratios is developed. Coal rank is valuable for defining parameters of a coal seam such as burn temperature, burn rate, and volume of burning seam.