Methods for introducing a first gas and a second gas into a reaction chamber
View Patent ↗Gas distribution units of fluidized bed reactors are configured to direct thermally decomposable compounds to the center portion of the reactor and away from the reactor wall to prevent deposition of material on the reactor wall and process for producing polycrystalline silicon product in a reactor that reduce the amount of silicon which deposits on the reactor wall.
1. A process for introducing a first gas and a second gas into a reaction chamber of a reactor, the reactor comprising at least one reaction chamber wall and a gas distribution unit for distributing the first gas and the second gas into the reaction chamber, the distribution unit comprising a distributor having a plurality of distribution openings including at least one peripheral opening and at least one central opening, each of the distribution openings having a channel portion and a throttle portion, the distribution unit further comprising an inlet block, an outer annular ring, an inner annular ring concentric to the outer annular ring, a product withdrawal tube concentric to the outer annular ring and inner annular ring and that extends through the distributor and inlet block, the space between the distributor, inlet block, outer annular ring and inner annular ring defining a first gas plenum, the space between the distributor, inlet block, inner annular ring and the product withdrawal tube defining a second gas plenum, the process comprising:
introducing the first gas into the first gas plenum and through the peripheral openings into the reaction chamber, the first gas passing through the channel portion at an angle with a longitudinal axis of the reaction chamber and through throttle portion of the distribution openings in a direction that is parallel with the longitudinal axis of the reaction chamber; and
introducing the second gas through the second gas plenum and through the central openings into the reaction chamber, the second gas passing through the channel portion and throttle portion of the distribution openings.
2. The process of claim 1 wherein the first gas comprises a gas selected from the group consisting of hydrogen, argon, helium and mixtures thereof.
3. The process of claim 2 wherein the second gas comprises a gas selected from the group consisting of silane, trichlorosilane, and mixtures thereof.
4. The process of claim 1 wherein the distributor comprises a plurality of cones and each distribution opening has a flare-out portion, the flare-out portion being in fluid communication with the throttle portion of the distribution opening and the cone, the gasses passing through the flare-out portion and cones.
5. The process of claim 4 wherein the cones that are in fluid communication with the flare-out portion of the peripheral distribution openings open into the reaction chamber.
6. The process of claim 1 further comprising introducing the first gas into the first gas plenum through a first gas inlet tube in the inlet block.
7. The process of claim 1 further comprising introducing the second gas into the second gas plenum through a second gas inlet tube in the inlet block.
8. The process of claim 1 wherein the first gas plenum is radially outward from the central openings.
9. The process of claim 1 further comprising mixing the first gas and the second gas adjacent the reaction chamber wall.
10. The process of claim 1 further comprising cooling the distributor to a temperature below which material thermally decomposes from either the first gas or the second gas.
11. The process of claim 1 wherein the central openings are parallel with the longitudinal axis of the reaction chamber from the bottom to the top of the distributor.
12. The process of claim 1 further comprising distributing the second gas evenly throughout the reaction chamber.
13. The process of claim 1 further comprising heating the second gas to a temperature above the point at which the second gas decomposes.