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Porous Materials Inhibition on Gas Explosion

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Tutor: XuMinQiang
School: Harbin Institute of Technology
Course: General and Fundamental Mechanics
Keywords: gas explosion,explosion suppression,metal mesh,ceramic foam,porous foam iron-nic
CLC: TD712.7
Type: PhD thesis
Year:  2013
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Coal is the primary energy in China, it will remain the principal place in theenergy structure over a long period in the future. Our coal mine more than95%is pitmining, and most of them belong to the gas emission mine. Coal mine severe gasaccident occurs frequently, it has serious threat with coal mine safety and workers oflife security. Traditional barrier burst facility which currently used to control orreduce gas explosion damage has not been able to achieve effective explosion effect.Thus, study on a new block of explosive materials and devices have been alreadyextremely urgent. In recent years, the porous material was concerned because of avariety of physical properties, such as porous, lightweight, high strength, vibration,damping and sound absorption, sound insulation, heat sinks and absorption ofimpact energy. It has been used in the field of civil works and military widely.Scholars have conducted extensive research on its performance at home and abroad,and has made a large number of research results. Bases on coal mine, the articleresearches on porous materials on the effect of barrier gas explosion propagation byusing theoretical analysis, experiment, mathematical modeling and Design andprediction method. In particular, the article have explorations and research on:Experimental pipeline, which section is30cm x30cm square, has designed tobroaden the pipe explosion of the flame of perspective, realized computersynchronous collection of the point pressure and the flame temperature data, so youcan study on flame temperature and pressure process of development ofcommunication. which is the largest gas explosion research section square pipeworkfor the current domestic pipeline seen within the reports and lead used flametemperature sensor on pipeline within explosion flame for research. Obtain thepressure, the temperature of flame propagation law, based on the experimentalresearch of quantitative gas explosion transmission in pipe.The ceramic foams (thickness5cm above) and metal mesh (30meshes and40meshes) restrain in the piping gas explosion was investigated. The experimentphenomenon shows that two kinds of materials have certain fire resistances, theanti-explosive shock wave damage performance of foamed ceramics is poorer butanti-agglutination is favorable. Anti-explosive shock wave damage performance ofmetal mesh is favorable but anti-agglutination is poorer. Study on flame temperatureof the pipe indicates that ceramic foam and wire mesh for flame temperature tomake the attenuation effect, reduces the flame temperature with the same conditionwithout obstruction, by comparison of flame temperature data, wire meshattenuation effects on flame temperature is better than ceramic foam. On the pipeline explosion overpressure of studies have shown that ceramic foam and wire mesh onexplosion overpressure with a certain degree of attenuation effect, reduces thestrength of the explosion and no obstructions under the same conditions, byattenuation of overpressure data comparison, foam ceramic material on theattenuation of blast overpressure effect is better than wire mesh materials. From theexperimental results, Layer and mesh of wire mesh, thickness and aperture ofceramic foam all have a great influence on effectiveness of explosion suppression,foam ceramic material on explosion suppression effect is small. Based on themechanism of experimental results and analysis of the influence of materialparameters on the explosion itself, the wire mesh and foam ceramic barrier pipe gasexplosion of pros and cons was summarized.The porous foam iron-nickel metal restrain in the piping gas explosion wasinvestigated. The experiment phenomenon shows that porous foam iron-nickel metalhas excellent acoustic attenuation performance, fire resistances, anti-shock wavedamaged performance and anti-sintering performance. Results of explosion flametemperature and overpressure on pipeline indicates that porous foam iron-nickelmetal can inhibition explosion wave energy of spread, reduces the explosionstrength with the same condition that without obstruction. Through the comparisonof the experimental data, the porous foam of Fe-NI metal is better than foamceramics and metal mesh on attenuation effect of flame temperature and explosiveoverpressure.Measuring point four, porous foam iron-nickel metal compared to40head40-wire mesh for maximum flame temperature decay rate increases38.8percent, than Al2O3ceramic foam that7cm large hole increases29.5percent. Onmeasuring point seven, porous foam iron-nickel metal compared to40head40-wiremesh on explosion overpressure decay rate increases29.9percent, compared to SICceramic foam that5cm large hole increases22.4percent. From the experimentalresults, the pore size, thickness and relative bulk density of porous foam iron-nickelmetal have a great influence on effectiveness of explosion suppression£¬ material ofiron-nickel metal components on explosion effects is small. Porous foam iron-nickelmetal attenuation mechanism of pressure and gas explosion flame wave wasanalyzed. Based on the results of the experiment and mechanism analysis of porousfoamed iron-nickel metal influence of parameters on the explosion itself, whenusing the porous material to explosion suppression, you should consider blockageratio and reasonable configuration parameters of materials in pipeline to achieve thereduction of material damage and strengthen the purpose of the explosion.Study on the mechanism of porous material attenuation overpressure andblocking flame, with experimental results comparative analysis of wire mesh,ceramic foam£¬bubble iron-nickel metal inhibition mechanism of gas explosion andexplosion suppression material advantages and disadvantages. Combined assessment method of attenuation explosion overpressure and flame temperature, acomprehensive quantitative evaluation algorithm of explosion suppression effectwas proposed, Established based on explosion overpressure, flame temperature andquenching parameters method of porous material cut blasting effect evaluationmathematical model, that will used for explosion effects assessment, offer scientificbasis for porous materials in experiment and its application in performanceassessment.Based on porous material, coal mining face blocked explosive devices and gasdrainage pipeline blocked explosive solid devices were designed. The device isexpected to address the limitations of existing passive and automatic barrier bursttechnology, it has explosion effect for secondary explosion and a series ofexplosions in coal mine underground.Using ABAQUS finite element analysissoftware for mechanical analyzing of porous materials, simulations in porousmaterials under conditions of underground gas explosion, simulation results showthat porous foam iron-nickel metal as a gas explosion suppression material canwithstand impact.The subject has discussed the action time control of porous barrierexplosive devices, predictive control concept was proposed. Coal mine gas emissionprediction model that based on Markov chains and gray dynamic theory wasestablished. Instance analysis shows that: Dynamic prediction of Markov chains andgrey prediction of high precision, with application. Finally the paper constructs apredictive control of coal mine gas emission rate.
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