ABSTRAKT

For thermal plasma processing of solid particles (including processes like plasma spraying, spheroidizing, decomposition, melting or fuming of fine particles, synthesis of ultrafine particles, etc.) injection and mixing, i.e. momentum, heat and mass transfer between solid particles and plasma flow is of great importance for the quality of the product. There are numerous effects involved in plasma-particle interactions. Effects have different ranges of influence in particular plasma process or reactor. This paper present the results of a numerical analysis of the evaporation and decomposition of B₂O₃ powder (with particle diameter less than 100 μm) injected in a nitrogen plasma axisymmetric, shielded reactor. This analysis serves as a basis for the optimization of the plasma reactor parameters, used for the plasma synthesis of BN ultrafine powder or boron powder production when B₂O₃ powder is used as a precursor. The computed fields of stream function and plasma temperature, particle trajectories and some parameters (plasma and particle temperature, particle Re, Nu and Kn^* numbers, influence of evaporation and noncontinuum effects on momentum heat and mass transfer and instantaneous particle diameter) along particle trajectories are presented and discussed.