Influence of filtration heat transfer on parameters and conditions for ignition of coal-water fuel particles
S.V. Syrodoy1, V.V. Salomatov2
1National Research Tomsk Polytechnic University, Tomsk, Russia
2Kutateladze Institute of Thermophsyics SB RAS, Novosibirsk, Russia
Keywords: водоугольное топливо, зажигание, фильтрация, внутренний тепло- и массоперенос, время задержки воспламенения, coal-water fuel, ignition, filtration flow, intrinsic heat and mass transfer, ignition delay time
Abstract
The paper describes a theoretical study on the influence of filtration of a mixture of gaseous products of pyrolysis and water vapor on the dynamic of ignition of coal-water fuel particles under conditions of high temperature heating. The developed mathematical model offers simulation of the process of ignition of coal-water fuel droplets under conditions close to the furnace space (characterized by intense radiation-convective heating) in typical boilers. Comparisons of experimental data (found previously) and simulation data on the ignition delay time ( t ign ) demonstrate good compliance. Simulation results show that filtration of water vapor and volatiles is a significant factor (influence up to 40 %) affecting the characteristics and conditions of ignition of coal-water fuel droplets. The higher velocity of the vapor-gas mixture flow through the porous structure of the fuel particle results in a longer ignition delay. The effect of using the “simplified” model of filtration heat transfer on the prognostic estimates of coal-water fuel ignition is analyzed. It is demonstrated that using of rather simple models for filtration heat transfer does not bring any significant errors in calculating the ignition delay time.
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