Document Type thesis Author Name Xie, Yanxuan URN etd-101811-193249 Title Study of Interaction of Entrained Coal Dust Particles in Lean Methane-Air Premixed Flames Degree MS Department Fire Protection Engineering Advisors Ali S. Rangwala, Advisor Vasudevan Raghavan, Advisor Kathy A. Notarianni, Department Head Alfonso Ibarreta, Committee Member Keywords burning velocity premixed flame explosion coal dust Date of Presentation/Defense 2011-10-18 Availability unrestricted
This study investigates the interaction of micron- sized coal particles entrained into lean methane Â– air premixed flames. In a typical axisymmetric burner, coal particles are made to naturally entrain into a stream of the premixed reactants using an orifice plate setup. Pittsburgh seam coal dust, with three particle sizes in the range of 0 to 25 Âµm, 53 to 63 Âµm, and 75 to 90 Âµm is used. The effects of different coal dust concentrations (10 Â– 300 g/m3) at three lean equivalence ratios, ϕ (methane-air) of 0.75, 0.80 and 0.85 on the laminar burning velocity are determined experimentally. The laminar burning velocity of the coal dust-methane-air mixture is determined by taking a shadowgraph of the resulting flame and using the cone-angle method. The results show that the addition of coal dust in methane-air premixed flame reduces the laminar burning velocity at particle size of 53 to 63 Âµm and 75 to 90 Âµm. However, burning velocity promotion is observed for 0 to 25 Âµm particles at ϕ = 0.80. Two competing effects are assumed involved in the process. The first is burning velocity promotion effect that the released volatile increases the gaseous mixture equivalence ratio and thus the burning velocity. The second is the heat sink effect of the coal particles to reduce the flame temperature and accordingly the burning velocity. A mathematical model is developed based on such assumption and it can successfully predict the change of laminar burning velocity at various dust concentration. Furthermore, the implication of this study to coal mine safety is discussed.
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