Hopper, or bin, screw feeder construction controlling discharge velocity profile
AssigneeAndritz-Ahlstrom Inc.
InventorJerry R. Johanson
Life of this patent
Estimating the term…
Abstract
A bin or hopper, preferably with one-dimensional convergence, has a slot outlet at its bottom for discharging bulk solid particulate material (such as coal, wood chips, sugar, plastic pellets, etc.) to a screw in a trough. The screw has varying flight diameter, shaft diameter, and average pitch along its length to a discharge so as to provide substantially uniform material flow velocity distribution along the slot outlet. One or more flow rate adjusters may regulate flow of material being transported by the screw. Each flow adjuster may be a vertical plate with a substantially straight-across bottom curved about a substantially horizontal axis, or with a bottom two-dimensional curvature.
Claims30
A bin or hopper discharge assembly comprising:
- a bin or hopper having at least one bottom slot outlet of effective length L;
- at least one screw in a trough and rotatable with a screw shaft of diameter d and having flights with a flight diameter f, and an average pitch P and an effective length substantially equal to L, said screw receiving material flowing from said at least one slot outlet;
- at least one discharge from said screw trough;
- said screw having a varying average pitch, shaft diameter, and flight diameter, and
- an effective length L;
- and
- said screw constructed to correspond to the formula [ ( f n + 1 ) 2 - ( d n + 1 ) 2 ] P n + 1 - [ ( f n ) 2 - ( d n ) 2 ] P n ( P n + P n + 1 ) / 2 = ( f L 2 - d L 2 ) P L L
- where fn, dn, and Pn are the flight diameter, shaft diameter and pitch of said screw at the nth pitch increment along the length L, and fL, dL, and PL are the flight diameter, shaft diameter, and pitch of the last or final pitch increment under the flow outlet near said screw discharge.
A bin or hopper assembly comprising:
- a bin or hopper having at least one bottom slot outlet of effective length L;
- at least one screw in a trough for receiving material from said at least one slot outlet and having an effective length substantially equal to L;
- said at least one screw rotatable with a screw shaft having a diameter, and having flights with a flight diameter, and an average pitch;
- a single discharge from said at least one screw trough;
- and
- at least one flow rate adjuster mechanism which provides flow regulation of material transported by said screw;
- and
- wherein said adjuster mechanism comprises a substantially vertical plate with a substantially straight-across bottom curved about a horizontal axis, and adjustable over a part of the length of the screw.
A bin or hopper assembly comprising:
- a bin or hopper having at least one bottom slot outlet of effective length L;
- at least one screw in a trough for receiving material from said at least one slot outlet and having an effective length substantially equal to L;
- said at least one screw rotatable with a screw shaft having a diameter, and having flights with a flight diameter, and an average pitch;
- a single discharge from said at least one screw trough;
- and
- at least one flow rate adjuster mechanism which provides flow regulation of material transported by said screw;
- and
- wherein said adjuster mechanism comprises a substantially vertical plate with a bottom with a two-dimensional curvature and adjustable over a part of the length of the screw.
Dependencies are inferred from the claim text.