Feeder

A fluid transfer apparatus for bulk material is disclosed. The transfer apparatus includes a rotor mounted on a rotatable shaft and including axially extending flow channels extending through the rotor parallel to the shaft, flow connectors for connecting a low-pressure flow of fluid and a high-pressure flow of fluid into and out of the axially extending flow channels, a casing enclosing the rotor, a pair of axially sealing plates disposed between the ends of the rotor and the casing, a pressurizing fluid fed into the chamber defined by the casing to pressurize the rotor, the flow connectors, and the axially movable sealing plates.