A Study of the Influence of Coal Suspension Additives on Combustion Stability and the Lower Methane Concentration Limit of Flame Propagation in Methane-Air Mixtures
A. V. Pinaev1, P. A. Pinaev1,2
1Lavrentyev Institute of Hydrodynamics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia
2Kutateladze Institute of Thermal Physics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia
Keywords: vertical and horizontal channels, combustion wave, methane, coal suspension, dual-fuel heterogeneous mixture, lower flame limit (LEL), fire safety
Abstract
The possibility of the existence of combustion waves in αCH4/air gas mixtures and αCH4/air/coal suspension dual-fuel heterogeneous mixtures (DGMs) with a methane volume concentration of α = 5 ÷ 8% was studied in a closed vertical shock tube and in a horizontal quartz tube open at one end. It was shown that the value of the lower concentration limit of methane flame propagation (LEL) α* and the flame stability are affected by the channel location relative to the gravity vector and the concentration of the coal suspension. In the vertical closed channel, combustion waves propagated from top to bottom in gas mixtures and DGMs at α ≥ 6%, but did not ignite at α ≤ 5.5%. In a horizontal tube, flame propagated in gas mixtures with α ≥ 6% and in a dual-fuel mixture with α ≥ 5.5%. Adding coal suspension to methane-air mixtures has little effect on flame velocity, increases brightness, and reduces the flame's LFL.
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