A numerical model of silane pyrolysis in a gas-solids fluidized bed

Recent experiments have shown that silane pyrolysis in a gas-solids fluidized bed may be an attractive way to produce ultra-pure silicon. Such a process would possess the general advantages of fluidized bed technology, namely, good contacting, thermal homogeneity, thorough mixing of particles, easy solids handling, and low pressure drop. Such a fluidized bed reactor is simulated using the two-fluid hydrodynamic model MFIX (Multiphase Flow with Interphase eXchanges; www.mfix.org), developed at the National Energy Technology Laboratory. Using MFIX three-dimensional simulations of silane pyrolysis are performed. The chemistry is described by a simple set of homogeneous and heterogeneous reactions. Results are compared to available experimental data where silicon deposition rates on a bed of alumina particles were measured as a function of temperature, bed height, and fluidization velocity.