Fluid jet seed particle generator for silane pyrolysis reactor

Claim 1

In a process for the production of high purity, polycrystalline silicon in a fluidized bed reaction zone by introducing a gas flow of silane or silane-hydrogen mixture into a fluidized bed of fine sized silicon particles suspended in a reaction zone by an upward flow of fluidizing gas, said reaction zone temperature being maintained within the decomposition temperature range of said silane and below the melting point temperature of silicon whereby said silane is decomposed to form silicon which deposits on the silicon particles in the fluidized bed to enlarge the same and cause said enlarged particles to descend as silicon product particles from said fluidized bed reaction zone through said upward flow of fluidizing gas into a collecting chamber having interior surfaces including side walls and a base portion having passages through which an upward flow of gas is introduced which passes into said fluidized bed reaction zone, the improvement which comprises providing in said collecting chamber, in addition to said upward flow of gas, a separate high velocity jet of gas above said base portion at a velocity which is in the range of about 100 to 1200 feet per second and which is from about 50 to 5000 times the velocity of said upward flow of gas said high velocity jet causing turbulence only in a portion of said collecting chamber so as to cause a portion of the enlarged silicon product particles in said chamber to impinge upon each other and be thereby comminuted to form smaller silicon particles which are transported upwardly into said fluidized bed in said reaction zone by said upward flow of gas passing through said perforated base.