The present invention relates to a device for dusting moving printed sheets, having a reservoir body for powder, an inlet for a carrier air flow terminating in the reservoir body and an outlet from the reservoir body for the carrier air flow loaded with powder, wherein the reservoir body is at least in sections divided into a delivery chamber and a storage chamber by means of a separating wall, and the inlet and the outlet communicate with the delivery chamber, and the storage chamber is used for filling the delivery chamber.

The vapor space above a bed of fluidizable particles in a chamber is variably controlled by extending a moveable conduit through the upper portion of the chamber to position the conduit inlet at a selectable height above the bed. Fluid flows uniformly up through the bed of particles to fluidize particles to a desired density in the fluid and at a desired rate of flow of such particles through the inlet to the conduit from the so adjusted volume of fluidization space in the chamber. The conduit is externally driven relative to the bed to maintain the particle fluidization volume and flow rate substantially constant. In apparatus form the pick-up conduit is carried by a piston member with sealing means, such as an O-ring, between the piston wall and the chamber sidewall. In an alternate embodiment the fluidizing gas is recirculated in a loop that includes the piston which is fluid permeable to bypass the conduit inlet. This permits a substantially constant rate of fluid flow to fluidize particles to a desired density, but permits independent control of the rate of flow of fluidized particles out of the chamber.

Method and device for suspending an ultrafine powder in a gas wherein a mass of powder to be dispersed in enclosing in a container between an axially movable piston and an axially fixed member adjacent to the ends of the container. The fixed member defines an inner counteracting surface facing the powder to be dispersed and has a peripheral gas inlet passage adjacent to the wall of the container and an axial passage extending out of a first end of the container. The second end of the container has a gas inlet. A first gas flow is injected into the second end of the container to move the piston towards the fixed member, thereby pressing the powder against the counteracting surface of the fixed member. A second gas flows into the first end of the container through the peripheral passage for eroding the powder adjacent to the counteracting surface and driving the eroded powder through the axial passage out of the container. The process and device can be utilized independent of conditions of orientation, of vibrations, and of external accelerations; yet is simple, light in weight, and inexpensive.

A metering and delivery system for feeding finely powdered coal to a combustion chamber includes a hopper containing finely ground coal, a vertical feed pipe extends from the hopper and a horizontal metering conduit is connected to the lower end of the feed pipe so that the coal provides a surface of repose in the metering conduit below an air flow opening with a bleed opening being downstream of the air flow opening. A venturi jet housing provides suction on the metering conduit drawing ambient air into the openings to entrain coal for injection by an injector lance into a combustion space. Metering of the coal is provided by inversely operated valves through which ambient air flows to the openings in the metering conduit.

Dispensing of particulate matter such as powder via a gaseous stream is facilitated by placing the powder in an amorphous, manipulable pouch through which the gaseous stream flows. Squeezing and manipulating the pouch results in manipulation of the contained powder to control the amount of powder entrained in the gas stream. The pouch is supported with its outlet opening disposed generally downstream of its inlet opening in order to provide a direct, rather than a tortious, flow path through the pouch.