Fluid bed reactor

providing a bed of seed particles inside a gas-tight chamber defined within a vessel having (a) a top head, (b) a bottom head, (c) a generally tubular side wall that surrounds a generally vertically extending centerline, (d) a solitary central inlet nozzle having an opening that is upwardly facing, the solitary central inlet nozzle further comprising an inner wall and an outer wall positioned concentrically around the inner wall, (e) a plurality of fluidization nozzles, each fluidization nozzle having an opening that is upwardly facing and is located at an elevation below the elevation of the opening of the solitary central inlet nozzle;

• and (f) one or more cooling gas nozzles extending radially into the chamber through the general tubular side wall above the bottom head and below a plurality of fluidization nozzles;
• flowing hydrogen, inert gas, or a mixture thereof through the one or more cooling gas nozzles into the chamber at ambient temperature and at insufficient velocity to fluidize the bed;
• flowing gas upwardly through the chamber at sufficient velocity to fluidize the bed, with at least a portion of the gas being provided by introducing a stream of silicon-bearing gas into the chamber through a passageway defined by the inner wall of the solitary central inlet nozzle and a flow of a secondary gas comprising hydrogen, inert gas, or a mixture thereof through an annular passageway between the inner wall and the outer wall of the solitary central inlet nozzle;
• injecting streams of hydrogen, inert gas, or a mixture thereof into the chamber through the plurality of fluidization nozzles, the opening of each fluidization nozzle being positioned and the gas flow being regulated such that the streams contain the injected stream of silicon-bearing gas in a plume at a core region of the chamber near the centerline;
• and
• heating the contents of the chamber sufficiently that silicon is released from the silicon-bearing gas and deposited onto the seed particles to produce silicon-coated product particles.

A heated silicon deposition reactor system, comprising:

• a vessel having an outer wall;
• at least one heater positioned inwardly of the outer wall;
• a removable concentric liner positioned inwardly of the at least one heater, the liner having an inner surface which defines a reaction chamber;
• a seed nozzle for introducing a plurality of seed particles into the reaction chamber;
• a central inlet nozzle comprising an inner wall and an outer wall positioned concentrically around the inner wall, the inner wall defining a passageway positioned to channel a flow of a primary gas comprising a silicon-bearing gas upwardly into the reaction chamber, the inner wall and the outer wall defining an annular passageway positioned to channel a flow of a secondary gas upwardly into the reaction chamber;
• a plurality of fluidization nozzles, wherein each fluidization nozzle has an outlet opening into the reaction chamber;
• at least one cooling gas nozzle opening into the reaction chamber below the plurality of fluidization nozzles;
• and
• at least one outlet for removing silicon-coated product particles from the vessel.