Pneumatic conveyor for granular materials

• US 5,350,257 A
• Filed: 01/12/1994
• Issued: 09/27/1994
• Est. Priority Date: 09/18/1992
• Status: Expired due to Fees

• Current Assignee: MAC Equipment, Inc. (Schenck Process Holding GmbH)
• Original Assignee: MAC Equipment, Inc. (Schenck Process Holding GmbH)
• Inventors: Remmers, Theodore L., Newbolt, Richard E.
• Primary Examiner(s): Cherry, Johnny D.
• Assistant Examiner(s): Pike, Andrew C.
• Application Number:
  US08/180,573
• Time in Patent Office: 258 Days
• Field of Search: 406/73, 406/75, 406/122, 406/124, 406/134, 406/136, 406/146
• US Class Current: 406/75
• CPC Class Codes: B65G 53/22 the systems comprising a reservoir, e.g. a bunker

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. The air pressure additionally passes through the material within the inside of the feeder to pressurize the upper portion of the pressure vessel. With this arrangement the pressure on each side of the material within the feeder is equal, allowing a normal gravity feed of the material through the hopper. The equalized pressures on the interior and exterior of the feeder aid in preventing damage to the feeder.

Claims

1. A pneumatic conveyor for granular, cylindrical, or flake material, said conveyor comprising:

a conduit having an inlet nozzle adapted to be connected to a source of entraining air, said conduit adapted to allow the material entrained in said air to pass therethrough;

a pressure vessel defining an interior cavity and having an inlet opening for receiving the material therethrough, a pressure valve operatively associated with said inlet opening and allowing a substantially airtight seal across said opening, and an outlet throat in communication with said conduit at a position downstream of said inlet nozzle; and

a metering device mounted within said cavity at a position interposed between said inlet opening and said outlet throat and providing a metered gravimetric flow of the material received from said inlet opening to said outlet throat, an outlet conduit of said metering device extending into, but being spaced from, said outlet throat by an outlet gap defining an open passage through which the material does not flow, said outlet gap being located intermediate at least a portion of a periphery of said outlet conduit of said metering device and said outlet throat, whereby said cavity of said vessel, and an interior and exterior of said metering device, are pressurized at a level at least substantially equal to that in said conduit.

2. A conveyor as in claim 1, further comprising a pressure regulator operatively associated with said inlet nozzle of said conduit.

3. A conveyor as in claim 1, wherein said metering device includes:

an inlet interposed between said pressure vessel inlet opening and said outlet conduit of said metering device;

a tray between said inlet and said outlet conduit of said metering device, said tray being mounted for reciprocation in a plane substantially perpendicular to material flow through said vessel and including a plurality of vanes extending in spaced parallel relation perpendicular to said reciprocation; and

means for causing said reciprocation.

4. A conveyor as in claim 3, wherein said inlet of said metering device includes a hopper tapered from a position in close proximity to interior walls of said pressure vessel to a position adjacent said tray.

5. A conveyor as in claim 3, wherein said means for causing reciprocation comprises an air motor.

6. A conveyor as in claim 3, wherein the material comprises a ready-to-eat cereal, and a mass of said cereal is located in said hopper.

7. A method of pneumatically conveying granular, cylindrical, and flake material, said method comprising the steps of:

passing an entraining airstream through a conduit;

introducing said material into a pressure vessel having an inlet and an outlet throat, with said outlet throat being in operative communication with said conduit, thereby subjecting said pressure vessel to a substantially constant air pressure;

passing said material through a metering device within said vessel intermediate said inlet and said outlet throat, and subject to said pressure, to dispense a substantially constant gravimetric flow from an outlet conduit of said metering device, said outlet conduit extending into, but being spaced from, said outlet throat by an outlet gap defining an open passage through which the material does not flow, said outlet gap being located intermediate at least a portion of a periphery of said outlet conduit of said metering device and said outlet throat, whereby said substantially constant flow of said material passes into said conduit through said outlet conduit of said metering device and is entrained within said airstream for passage through said conduit; and

permitting air pressure from said airstream to pass through said outlet gap between said outlet conduit and said outlet throat to thereby maintain said substantially constant air pressure within said vessel.

8. A method as in claim 7, wherein said step of introducing said material comprises introducing a read-to-eat cereal.