【作者】 时国庆；

【导师】 王德明；

【作者基本信息】 中国矿业大学 ， 安全技术及工程， 2010， 博士

【摘要】 三相泡沫防灭火技术能集灌浆、注氮、喷洒阻化剂的防灭火优势于一体,在煤矿防灭火中得到广泛应用,但由于缺乏对其流动特性的研究,导致三相泡沫的应用工艺设计缺乏理论支持,对其在采空区中的防灭火作用也认识不足,为此,论文从研究三相泡沫基本流变特征入手,重点对三相泡沫在采空区的流动特性进行了较系统的研究。研究成果对于优化三相泡沫应用工艺设计,提高三相泡沫防灭火效率具有重要作用。为得到三相泡沫的粘度特征,论文开展了三相泡沫的流变性研究。测试了三相泡沫的剪切应力与剪切速率关系,采用灰关联分析法优选了三相泡沫的流变模式,建立了三相泡沫的本构方程,指出三相泡沫是一类屈服假塑性流体;计算了三相泡沫在采空区的启动压力梯度,结合对工作面进回风侧间压差的理论分析,认为采空区漏风动力不足以驱动采空区内的三相泡沫,基于此,指出三相泡沫具有阻断采空区漏风,减少灾害气体涌出的功能。为了给理论研究三相泡沫的渗流特性奠定实验基础,论文制作了渗透装置,构建了实验测试系统,开展了三相泡沫渗流特性的实验研究。测取了三相泡沫渗流压降和流量之间的关系,分析了三相泡沫渗流的阻力特性,结果表明:低速渗流阶段三相泡沫具有较为明显的剪切稀化特征;浆液的浓度、多孔介质的渗透率是渗流阻力的主要影响因素,而发泡倍数对三相泡沫的渗流特性影响较小;采用通过本构方程得到的表观粘度对渗流实验进行了数值计算,得到了与实验数据相一致的结果,证明基于本构方程的表观粘度可用于三相泡沫的渗流计算,进而找到了理论计算三相泡沫渗流特性的途径。在实验研究和理论分析的基础上,确立了三相泡沫在采空区的渗流方式,应用多相流、渗流理论建立了三相泡沫在采空区渗流的三维非稳态数学模型;为对数学模型进行验证,在露天矿原小煤窑大范围采空区火灾的治理中开展了三相泡沫流动特性的试验与数值模拟研究,现场考察了三相泡沫的堆积高度,扩散距离等流动特性,并通过模拟结果与现场观测的对比对数学模型进行了验证。针对采空区空间隐蔽,现场观测三相泡沫流动特性难度大的特点,论文将CFD模拟技术引入到三相泡沫在采空区流动特性的研究中,提出了三相泡沫在采空区中流动特性的数值模拟方法。采用该方法研究了通过上顺槽预埋管灌注时,三相泡沫在综放面采空区中的渗流特性,得到了三相泡沫在采空区中的堆积高度、扩散宽度以及主要影响因素。研究表明,三相泡沫的流动特性受工作面倾角和灌注流量的影响较为显著,随灌注流量的增加三相泡沫的堆积高度和扩散宽度都会增加;随工作面倾角的增加,三相泡沫的扩散宽度有大幅减少,而堆积高度变化不明显;通过大量模拟研究,绘制了堆积高度、扩散宽度与流量和工作面倾角之间的关系曲线。在实验和理论研究成果的指导下,对三相泡沫防治煤炭自燃的工艺进行了优化设计与应用,解决了大型综放面采空区防火、大范围地表采空区煤自燃火区治理、综放面近采空区隐蔽火源治理等技术难题,取得了较好的防灭火效果,三相泡沫的防灭火效率得到了充分发挥。更多还原

【Abstract】 Technology of Three-phase foam for mine fire fighting has the merits of grouting, nitrogen injection and inhibitor spraying, so it has been widely used in mine fire fighting. However, because that it is lacking of research on the characteristic of three-phase foam’s flow behaviors in mine goaf, the application process design has always been lacking of theoretical support, the role of three-phase foam for fire fighting hasn’t been absolutely recognized, In order to change this situation, foam flow behaviors in mine goaf has been studied systematically in the paper. Research results is very useful for improving process design level and the efficiency of fire fighting.In the paper, in order to obtain the viscidity characteristic, the rheological property of three-phase foam was studied. For the three-phase foam, the relationship between shear stress and shear rate was tested, the optimal rheological model was selected by the grey correlation analysis, and the constitutive equation was constructed which point out that the three-phase foam belong to the kind of yield pseudoplastic fluid. And then the result of the starting pressure gradient computed showed that the leaking air force couldn’t drive the three-phase foam. Finally author put forward that the three-phase foam could interdict the leaking air and reduce the emission of hazardous gas in goaf.In order to provide experimental fundamentals for theoretical study on seepage characteristics of three-phase foam, the osmosis device and the experimental measurement system were designed and constructed, and the experiment about the seepage characteristics of three-phase foam was completed. The pressure drop and flow during the seepage of three-phase foam was measured to analyze the resistance seepage characteristics of three-phase foam. The results showed that the three-phase foam is characterized by shear thinning in low speed seepage; the main factors to the seepage resistance of three-phase foam are concentration of slurry and permeability of porous media, while the foaming multiple has little influence. The consistence between the results of the experiment and the numerical computation on the seepage experiment of three-phase foam based on the apparent viscosity from constitutional equation is found, and so it is testified that the apparent viscosity of three-phase foam which is derived from constitutional equation could be applied in the seepage calculation. On the basis of the experimental study and theoretical analysis,seepage manner of three-phase foam in the gob is established, and three dimensional unsteady mathematical model of three-phase foam which seeps in the gob is established by the use of theory of multiphase flow and seepage flow. In order to verify the mathematical model, experimental and numerical simulation study on the flow characteristics of three-phase foam are carried out in the control of large area gob fire of small coal pits in surface mine, and characteristics of three-phase foam such as stack height and diffusion distance, etc are inspected on the spot, and the simulation results is coincident with the conclusions which is obtained by field observations.Taken into account of the difficulty to observe the flow characteristics of three-phase foam in the gob hidden space, CFD simulation technology is drawn into the study on the flow characteristics of three-phase foam in the gob and numerical simulation method is raised to study the flow characteristics of three-phase foam. The flow characteristics of three-phase foam in fully mechanized caving face are studied when it poured by embedded pipe in upper crossheading. which shows that stacking height and diffusion width of three-phase foam can each reach to 3.62m and 36.9m, and stacking height and diffusion width are notably affected by the face’s dip angle and perfusion flow. Stacking height and diffusion width of three-phase foam are increased with the increase of perfusion flow, while the diffusion width of three-phase foam is greatly decreased with the increase of face angle. Relation curves of stacking height and diffusion width along with flow rate and face angle are drawn through a great deal of simulation study.Under the guidance of the results of experimental and theoretical research, design method of application process for three-phase foam is established, and perfusion technology of three-phase foam in coal mine has been optimal designed and applied, which solve the fire prevention in large-scale fully mechanized caving face gob, large scale coal spontaneous combustion fire in surface gob and concealed fire at the near gob eare in fully mechanized caving face, and preferable fire prevention effect has been achieved as well as the full play of three-phase foam in fire extinguishing efficiency.更多还原