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Numerical studies of heat transfer parameters during injection feeding of powders into the rail steel melt in ladle-furnace

Technological features of powdered reagents injection into the melt using a submersible tuyere were investigated for the research and development of the main provisions of rail steel out–of-furnace treatment in a ladle-furnace. Authors analyzed the characteristics of influence of a directed heat flow through the tuyere conditional separation wall from metal to two-phase gas-powder flow under purging conditions. Using numerical methods, were determined the parameters of influence of the submersible tuyere surface temperature on characteristics of the transporting gas, concentration of the powder and its density, and on characteristics of the gas-powder flow, including the aerodynamic drag coefficient, pressure of the transporting gas, difference in phase velocities, equivalent diameter, and particle shape coefficient. The obtained experimental results show that at the same flow rate of the transporting gas, more significant heat flows, ensuring stable operation of the blowing device, are created by using a lighter gas (nitrogen), while the diameter of powdered particles does not affect the amount of heat transferred from the tuyere wall to the transporting gas. It was established that when using submersible tuyeres and heating the gas–powder flow to a temperature of 500 – 600 °C, the strength of the interfacial interaction changes by 2 to 10 times depending on the particle shape coefficient, concentration of the injected powder, pressure of the transporting gas, difference in phase velocities and density of the powder.