New Approaches in Engineering Research Vol. 5

Abstract

The method of plasma pyrolysis of monosilane is used to examine the continuous technical process of producing «solar» silicon granules and nanosilicon powder. The time of decomposition, e.g. at 1800^oC, is 2×10^-5 s. At a plasma velocity of about 1000 m/s, decomposition of monosilane will take place at a distance of 2 cm. The energy consumption is calculated as min QSi = 1.69 kWh/kg Si, GSi = 50 kg/h Si at useable plasmatron power W = 100 kW, volume ratio VAr/VH2 = 0.2/0.8, and reaction zone length L = 0.06 m. The topic of modelling the steady-state cooling and condensation of silicon vapours and molten silicon droplets formed by the interaction of monosilane with a plasma jet was taken into consideration. The impact observed when the condensation reactor is coupled with the granulator, i.e. where the mechanisms of condensation of silicon vapours into a liquid film and conversion of flow of this film into a droplet one take place on its working surface at the same time, leads to the formation of a new condenser – granulator concept. Nanopowder is created using turbulent thermal plasma fluxes. Based on this technique, it is conceivable to develop high-efficiency equipment for continuous manufacture of low-cost silicon for photovoltaics and materials required for future generations of Lithium-ion batteries with minimal capital and operating cost.