Production of polycrystalline silicon in substantially closed-loop systems
First Claim
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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;
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Abstract
Production of polycrystalline silicon in a substantially closed-loop process is disclosed. The processes generally include decomposition of trichlorosilane produced from metallurgical grade silicon.
24 Citations
21 Claims
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1. A substantially closed-loop process for producing polycrystalline silicon, the process comprising:
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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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A substantially closed-loop process for producing polycrystalline silicon, the process comprising:
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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 the first effluent gas into a first effluent gas separator to separate hydrogen from trichlorosilane and silicon tetrachloride, the trichlorosilane and silicon tetrachloride being introduced into a chlorinated gas purification system to produce a purified trichlorosilane stream and a purified silicon tetrachloride stream; introducing silicon, an amount of silicon tetrachloride from the purified silicon tetrachlorinated product stream and hydrogen from the first effluent gas into a second fluidized bed reactor to produce a second effluent gas comprising trichlorosilane, hydrogen chloride, unreacted hydrogen and unreacted silicon tetrachloride; introducing the second effluent gas into a second effluent gas separator system to separate trichlorosilane and unreacted silicon tetrachloride from hydrogen, the trichlorosilane and unreacted silicon tetrachloride being introduced into the chlorinated gas purification system; introducing hydrogen and hydrogen chloride from the second effluent gas into a separation system to separate hydrogen and hydrogen chloride, the separation system comprising a hydrogen separator that is a bubbler, a hydrogen purifier that is an adsorber and a hydrogen chloride purifier that is a distillation column, wherein; the hydrogen and hydrogen chloride are introduced into the hydrogen separator to produce a hydrogen recycle gas and a hydrogen chloride recycle gas; the hydrogen recycle gas is introduced into a hydrogen purifier to remove impurities from the hydrogen recycle gas; the hydrogen chloride recycle gas is introduced into a hydrogen chloride purifier to remove impurities from the hydrogen chloride gas; and the purified hydrogen recycle gas is introduced into at least one of the first fluidized bed reactor and the second fluidized bed reactor; introducing the purified hydrogen chloride recycle gas and silicon into a chlorination reactor to produce a chlorinated product gas comprising trichlorosilane and silicon tetrachloride; introducing the chlorinated product gas into the chlorinated gas purification system; introducing the purified trichlorosilane stream produced by contacting hydrogen chloride and silicon into the first fluidized bed reactor to produce polycrystalline silicon. - View Dependent Claims (16, 17, 18, 19, 20, 21)
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Specification