Fluidized bed reactor and method of producing granular polysilicon

Patent metadata

Field	Value
Publication number	US-2016101982-A1
Application number	US-201414889347-A
Country	US
Kind code	A1
Filing date	Apr 28, 2014
Priority date	May 6, 2013
Publication date	Apr 14, 2016
Grant date	—

Abstract

The fluidized bed process for preparing polysilicon by chemical vapor deposition is improved by positioning at least one Laval nozzle upstream from a gas inlet into the reactor.

First claim

1 .- 10 . (canceled)

11 . A fluidized bed reactor for producing granular polysilicon, comprising: a vessel having an inner reactor tube for a fluidized bed of granular polysilicon, and a reactor base; a heating device for heating the fluidized bed in the inner reactor tube; at least one opening in the reactor base for feeding fluidizing gas, and at least one opening in the reactor base for feeding reaction gas; a device for removing reactor offgas; a feed apparatus for feeding silicon seed particles; and a withdrawal conduit for granular polysilicon product, wherein a Laval nozzle is situated upstream of at least one of the openings in the reactor base, suitable for supercritically expanding at least one mass stream fed to the fluidized bed reactor.

12 . The fluidized bed reactor of claim 11 , which has at least two openings in the reactor base, each opening having a Laval nozzle situated upstream from the opening.

13 . The fluidized bed reactor of claim 11 , which has one or more groups of openings in the reactor base, each group comprising at least two openings, wherein a Laval nozzle is situated upstream of each group of openings.

14 . The fluidized bed reactor of claim 11 , comprising one or more groups of openings in the reactor base, each group comprising at least two openings, wherein one Laval nozzle is situated upstream of each opening, and at least one further Laval nozzle upstream of said one Laval nozzle upstream of said each opening.

15 . The fluidized bed reactor of claim 11 , wherein the at least one opening in the reactor base upstream of which a Laval nozzle is situated comprises a gas distributor.

16 . The fluidized bed reactor of claim 11 , wherein the at least one opening in the reactor base upstream of which a Laval nozzle is situated comprises a hole in the base plate, a valve, or a nozzle.

17 . A method for producing granular polysilicon in a fluidized bed reactor, comprising fluidizing silicon particles by means of a fluidizing gas that is fed via at least one opening in the reactor base of the fluidized bed reactor, forming a fluidized bed which is heated via a heater to a temperature of 850-1200° C., feeding a silicon-containing reaction gas via at least one opening in the reactor base of the fluidized bed reactor, and depositing silicon onto the silicon particles, wherein at least one mass stream of fluidizing gas or reaction gas fed to the fluidized bed reactor is expanded supercritically, by a Laval nozzle situated upstream of at least one of the openings in the reactor base which expands the at least one mass stream by overpressure prevailing in the Laval nozzle.

18 . The method of claim 17 , wherein the fluidizing gas is H 2 and the silicon-containing reaction gas is TCS.

19 . The method of claim 17 , wherein a fluidized bed reactor of claim 11 is employed as a fluidized bed reactor.

Assignees

• Wacker Chemie Ag

Inventors

• Pedron Simon
• Forstpointner Gerhard

Classifications

• B01J2208/00761

  Discharging · CPC title

• B01J8/1872

  Details of the fluidised bed reactor (B01J8/1836 takes precedence) · CPC title

• B01J2208/00752

  Feeding · CPC title

• B01J8/1836

  Heating and cooling the reactor (B01J8/42 takes precedence) · CPC title

• C23C16/24

  Deposition of silicon only · CPC title