Powder feeder and methods for transporting particulate material

Abstract

A powder feeder, especially useful for transporting particulate materials at very low, yet precisely controlled, rates. A container preferably a closed vessel, is provided with an orifice to admit gas up through the bottom of the vessel in a high velocity column (or jet). A pair of concentric conduits is suspended from the top of the vessel in approximately axial alignment with the orifice so that the column of gas is captured within the outer conduit and substantially all enters the inner conduit. Particulate material (such as metal powder) is stored in the space between the outer conduit and the walls of the vessel. The spacing of the outer conduit from the bottom of the vessel is adjusted to admit particulate material to the vicinity of the orifice at a controlled rate but to prevent flooding of the space between the orifice and the conduits. When gas is forced through the orifice, particulate material is lifted by the venturi pressure effect created by the gas column. Most of the particulate material lifted by the gas column is transported up the inner conduit and out the top of the vessel; the remainder rises up the annular space between the conduits and is spilled out into the interior of the vessel on top of the stored material.

Dependencies are inferred from the claim text.