Abstract: A vacuum modulating air control valve includes a valve body with air intake ports, an output port, and a valve throat. A valve member is slidably mounted within the valve body between open positions relative to the valve throat and a closed position, to which the valve member is urged by a valve spring. A pneumatic cylinder has a piston forming a vacuum chamber and has a piston rod connected to the valve member. The output port is connected to a feedpoint of a vacuum conveying system, and the vacuum chamber is connected to a vacuum line communicating with the vacuum conveying system. A vacuum level within the vacuum chamber retracts the valve member from the throat, thereby admitting ambient air into the vacuum conveying system to control a material-to-air ratio within the system.

Abstract: A vacuum modulating air control valve includes a valve body with air intake ports, an output port, and a valve throat. A valve member is slidably mounted within the valve body between open positions relative to the valve throat and a closed position, to which the valve member is urged by a valve spring. A pneumatic cylinder has a piston forming a vacuum chamber and has a piston rod connected to the valve member. The output port is connected to a feedpoint of a vacuum conveying system, and the vacuum chamber is connected to a vacuum line communicating with the vacuum conveying system. A vacuum level within the vacuum chamber retracts the valve member from the throat, thereby admitting ambient air into the vacuum conveying system to control a material-to-air ratio within the system.

Abstract: A continuous dense phase conveying system and method regulates and modulates the volume of gas flowing at a low velocity within a material conveying pipe. In response to air volume leakage through a rotary airlock valve, a controller adjusts a flow control valve to maintain the volume of air for conveying at a selected level. The flow control valve has a venturi-shaped output section. The flow control valve is more than 90% efficient (e.g., less than 10% pressure drop across the valve) and has an output that varies linearly, over a wide range, with adjustment of the valve.

Abstract: A rotary airlock valve is provided with a ring seal. The airlock includes a tapered tubular housing formed about a longitudinal axis. The housing includes inlet and outlet ports to receive and discharge the material. The housing further includes end plates at opposite ends thereof which rotatably support opposite ends of a rotor assembly. The rotor assembly rotates within the housing about the longitudinal axis. The rotor includes multiple vanes with shrouds on opposite ends thereof. Seal rings are mounted upon inner surfaces of the end plates and biased towards outer surfaces of the shrouds to maintain a sealed relation between the shrouds and end plates. An expandable biasing tube is mounted proximate the seal rings to bias each seal ring toward and against the shroud. Each biasing tube is hollow to receive a predetermined amount of pressurized air.

Abstract: A pneumatic conveyor for granular materials which includes an apparatus for introducing the material into the entraining air stream. The apparatus includes a pressure vessel having means at its upper end for receiving allotments of material from an unpressurized source. Located within the vessel below the inlet is a feeder of the type having a hopper leading to reciprocating tray. The tray includes a plurality of inclined blades and provides a constant metered flow of the material between the blades to an outlet located adjacent the lower end of the pressure vessel. The lower end of the pressure vessel is connected to a transition throat leading directly to the conveying line through which passes the entraining air stream. The outlet of the feeder is spaced from the opening of the transition throat such that air pressure may pass about the exit and pressurize a lower portion of the pressure chamber outside of the feeder.