| 摘要 |
<p>A powder feeder pick up tube having a central powder delivery tube receiving powder entrained in a propellant gas, an outer concentric tube delivering propellant gas to the powder delivery tube and evenly entraining powder in the gas as the powder enters the powder delivery tube. The propellant delivery tube has an inwardly curving end that forms a gap with the open end of the powder delivery tube, and the geometry of the operational characteristics of the pick-up tube. Variations on the basic pick-up tube include a concentric fluidizing tube surrounding the propellant delivery tube and locally fluidizing powder around the opening of the powder pick-up tube. The shape of the fluidizing orfice at the outlet of the fluidizing tube may be modified to alter its fluidizing characteristics. The tube is immersed in a hopper of powder when operating and the entire hopper may be fluidized and vibrated to assist the operation of the pick-up tube. Passing fluidizing gas through the fluidizing tube allows a reserve tube to remain immersed in a powder hopper without clogging when not in use.</p> |
