Patent ID: 8956584
Filing Date: 2015-02-17
Classification: C01B

Abstract:
1. A substantially closed-loop process for producing polycrystalline silicon, the process comprising: introducing trichlorosilane into a disproportionation system to produce silicon tetrachloride and silane, the disproportionation system comprising a first distillation column, a second distillation column, a third distillation column, a first disproportionation reactor and a second disproportionation reactor, wherein: introducing the overhead fraction produced from the disproportionation system into a fluidized bed reactor to produce polycrystalline silicon and an effluent gas comprising hydrogen and unreacted silane, the overhead fraction comprising silane; introducing an amount of silicon tetrachloride produced from the disproportionation system and an amount of hydrogen from the effluent gas into a hydrogenation reactor to produce trichlorosilane and hydrogen chloride; introducing an amount of hydrogen chloride produced from the hydrogenation reactor and silicon into a chlorination reactor to produce a chlorinated gas comprising trichlorosilane and silicon tetrachloride; and introducing trichlorosilane produced from the chlorination reactor to the disproportionation system to produce silicon tetrachloride and silane.