Gas feeding apparatus for powder and granular material feeder

A gas feeding apparatus for a powder and granular material feeder, in which a powder and granular material feed case is formed by erecting an outer tube on a bottom plate, an inner tube having upper and lower openings is provided above the bottom plate via a powder and granular material discharge clearance, and an annular passage is formed between the inner and outer tubes by connecting an outside surface of the inner tube to an upper end of the outer tube concentrically using a donut-shaped lid body,

• wherein an upright rotary shaft is provided in a center of the bottom plate, a boss portion is provided on an upper portion of the upright rotary shaft, a plurality of rotary blades extending over the bottom plate are provided on an outer periphery of the boss portion at a fixed distance from the bottom plate, and respective tip ends of the rotary blades are connected to a rotating wheel provided to extend around an inner peripheral surface of the outer tube, and
• wherein a discharge port is formed in the bottom plate as an opening in the annular passage such that a powder and granular material spread over the annular passage at a predetermined angle of repose from the powder and granular material discharge clearance is fed to the discharge port by the rotary blades,
• the gas feeding apparatus being characterized in that a first feed port for a gas is provided in the bottom plate on a lower surface of the boss portion so that the gas can be fed into a space between an upper surface of the bottom plate and the lower surface of the boss portion, and
• an annular damming plate is formed concentrically with the inner and outer tubes on the lower surface of the boss portion on an outer side of the first feed port so that the gas fed into the space through the first feed port can be fed in a radial direction via slits provided around the annular damming plate.