Patent ID: 9394180
Filing Date: 2016-07-19
CPC Classification: B01J,C01B

Claim Text:
1. A substantially closed-loop process for producing polycrystalline silicon, the process comprising: introducing trichlorosilane and hydrogen to a first fluidized bed reactor to produce polycrystalline silicon and a first effluent gas comprising silicon tetrachloride, hydrogen and unreacted trichlorosilane; introducing silicon and an amount of silicon tetrachloride and hydrogen from the effluent gas into a second fluidized bed reactor to produce a second effluent gas comprising trichlorosilane and unreacted hydrogen and unreacted silicon tetrachloride; contacting hydrogen chloride and silicon to produce trichlorosilane and silicon tetrachloride; introducing the trichlorosilane produced by contacting hydrogen chloride and silicon into the first fluidized bed reactor to produce polycrystalline silicon; and adding chlorine to one or more process streams as a make-up, wherein the molar ratio of chlorine added as a make-up to polycrystalline silicon product that is produced is less than about 2:1.