Process for the gaseous phase production of metal oxide particles
AssigneeTioxide Group Limited
InventorKenneth Arkless
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Abstract
Process and apparatus for the production of finely-divided metal oxides by the oxidation of the corresponding metal halide wherein a secondary gas is introduced into a heated primary gas through apertures in the reaction zone wall, the apertures formed with at least two different cross-sectional areas along their length, the small cross-sectional area being at the inlet end of the aperture for the secondary gas.
Claims17
In a process for the production of finely-divided metal oxides which comprises oxidizing the corresponding metal halide with an oxidizing gas by introducing into one end of a reaction zone a hot stream of primary gas selected from an inert gas, the oxidizing gas or the metal halide, introducing a secondary gas selected from the oxidizing gas, the metal halide or mixtures thereof into the primary gas stream through an injection device surrounding at least part of the reaction zone, said injection device comprising a wall having a plurality of separate apertures therethrough, each aperture having an inlet end and an outlet end and each aperture connecting the reaction zone to a secondary gas jacket, said wall dividing said reaction zone from said jacket, the inlet end of said aperture being at the interface of said wall and said reaction zone, the secondary gas being supplied to the reaction zone through said jacket in such a manner that it cools the wall of the injection device and is thereby preheated before it passes through the apertures into the primary gas stream, the improvement comprising forming said apertures with at least two segments of different cross-sectional areas along their length, the segment of smaller cross-sectional area being at the inlet end of the apertures for the secondary gas, and the segment of larger cross-sectional area being at the outlet end of said apertures, said segment of larger cross-sectional area being of sufficient cross-section and extending for a sufficient length of said apertures to preclude substantial accretion of metal oxide around the edge of the aperture.
In a process for the production of finely-divided metal oxides which comprises oxidizing the corresponding metal halide with an oxidizing gas by introducing into one end of a reaction zone a hot stream of primary gas selected from an inert gas, the oxidizing gas or the metal halide, introducing a secondary gas selected from the oxidizing gas, the metal halide or mixtures thereof into the primary gas stream through an injection device surrounding at least part of the reaction zone, said injection device comprising a wall having a plurality of separate apertures therethrough, each aperture having an inlet end and an outlet end and each aperture connecting the reaction zone to a secondary gas jacket, said wall dividing said reaction zone from said jacket, the inlet end of said aperture being at the interface of said wall and said reaction zone, the secondary gas being supplied to the reaction zone through said jacket in such a manner that it cools the wall of the injection device and is thereby preheated before it passes through the apertures into the primary gas stream, the improvement comprising forming said apertures with at least two segments of different cross-sectional areas along their length, the segment of smaller cross-sectional area being at the inlet end of the apertures for the secondary gas, and the segment of larger cross-sectional area being at the outlet end of said apertures, said segment of larger cross-sectional area being of sufficient cross-section and extending for a sufficient length of said apertures to preclude substantial accretion of metal oxide around the edge of the aperture, the length of said segment of larger cross-section being at least three times the diameter of said segment of larger cross-section.
Dependencies are inferred from the claim text.