Method and apparatus for producing granular silicon
Silicon granules are produced by chemical vapor deposition on seed particles inside a chamber within a fluidized bed reactor. The chamber contains an obstructing member, or bubble breaker, which is sized and shaped to restrict the growth of bubbles inside the chamber and which has interior passageways through which a heated fluid passes to transfer heat to gas inside the chamber.
1. A method for producing granular silicon by thermal decomposition of a gas containing silicon, the method comprising:
passing a silicon-bearing gas upwardly through a fluidized bed of silicon particles inside a chamber within a reactor to deposit silicon from the silicon-bearing gas onto the particles;
providing an obstructing member that is positioned within the chamber, that hangs down from a top head of the reactor, that is configured to break up gas bubbles in the fluidized bed, and that comprises one or more conduits defining one or more passageways;
passing heated hydrogen through the one or more passageways at a temperature sufficient to transfer heat to the bed;
reheating hydrogen leaving the one or more passageways; and
injecting the reheated hydrogen into the chamber.
2. The method of claim 1 wherein:
the providing of an obstructing member comprises providing an obstructing member that comprises plural tubes that extend into the chamber and that define the one or more passageways; and
the passing heated hydrogen through the one or more passageways comprises passing the heated hydrogen in parallel through the plural tubes.
3. The method of claim 1 wherein:
the providing of an obstructing member comprises providing an obstructing member that comprises plural tubes that extend into the chamber and that define the one or more passageways; and
the passing heated hydrogen through the one or more passageways comprises passing the heated hydrogen in series through the plural tubes.
4. The method of claim 1 wherein the providing of an obstructing member comprises providing an obstructing member that comprises plural U-shaped tubes positioned to break up bubbles moving upwardly through the chamber.
5. A method for producing granular silicon by thermal decomposition of a gas containing silicon, the method comprising:
passing a silicon-bearing gas upwardly through a fluidized bed of silicon particles inside a chamber within a reactor to deposit silicon from the silicon-bearing gas onto the particles;
providing an obstructing member that is positioned within the chamber, that hangs down from a top head of the reactor, that is configured to break up gas bubbles in the fluidized bed, and that comprises plural U shaped tubes that extend into the chamber and that define the one or more passageways;
passing heated hydrogen through the one or more passageways at a temperature sufficient to transfer heat to the bed;
reheating hydrogen leaving the one or more passageways; and
injecting the reheated hydrogen into the chamber through an inlet located such that the reheated hydrogen participates in fluidizing the bed.