Granular metering system
An additive feeder assembly includes a supply reservoir having an outlet and an outlet tube having a first end in fluid communication with the outlet and a second end located vertically higher than the supply reservoir. An air stream transports a first granular material discharged from the supply reservoir and into the first end of the outlet tube to the second end of the outlet tube. A granular material distributor is in fluid communication with the second end of the outlet tube. The granular material distributor has a top end configured for attachment to a feed supply for a second granular material, a central portion located vertically below the top end and configured to mix the first granular material and the second granular material, and a bottom end configured for vertically discharging the mixed first granular material and second granular material.
1. An additive feeder assembly comprising:
a supply reservoir having an outlet;
an outlet tube having a first end in fluid communication with the outlet and a second end located vertically higher than the supply reservoir;
a means for transporting a first granular material discharged from the supply reservoir and into the first end of the outlet tube to the second end of the outlet tube; and
a granular material distributor in fluid communication with the second end of the outlet tube, the granular material distributor having:
a top end configured for attachment to a feed supply for a second granular material;
a center portion located vertically below the top end and configured to mix the first granular material and the second granular material; and
a bottom end configured for vertically discharging the mixed first granular material and second granular material
wherein the means for transportation comprises an air flow generator and a venturi.
2. The additive feeder assembly according to claim 1 , wherein the supply reservoir comprises a continuous metering device.
3. The additive feeder assembly according to claim 1 , wherein the means for transportation generates air speeds sufficient to carry the granular material vertically upwardly.
4. The additive feeder assembly according to claim 3 , wherein the air speeds are sufficient to prevent the granular material from adhering to the outlet tube.
5. The additive feeder assembly according to claim 1 , wherein the granular material distributor comprises:
a plenum chamber having a first cross sectional area;
an inlet opening upstream from the plenum chamber and in fluid communication with the plenum chamber, the inlet opening having a second cross sectional area such that the first cross sectional area is at least 10 times larger than the second cross sectional area;
an air discharge portion disposed vertically above the plenum chamber, the air discharge portion having a laterally directed outlet opening; and
a screen disposed between the plenum chamber and the air discharge portion, the screen having a mesh sized to retain granular material discharged into the plenum chamber from the inlet opening.
6. The additive feeder assembly according to claim 5 , wherein the first cross sectional area comprises a curved wall.
7. The additive feeder assembly according to claim 6 , wherein the inlet opening extends tangentially to the curved wall.
8. The additive feeder assembly according to claim 6 , further comprising a particle discharge portion located vertically below and in fluid communication with the plenum chamber.
9. The additive feeder assembly according to claim 8 , further comprising an outer box disposed around the plenum chamber, the outer box having a bottom opening disposed vertically below the lower portion.
10. The additive feeder assembly according to claim 9 , wherein the outer box comprises an upper cross sectional area above the lower portion and a lower cross sectional area, smaller than the upper cross sectional area, below the lower portion.
11. The additive feeder assembly according to claim 9 , wherein the air discharge portion has a top surface configured to direct granular particles in the outer box away from the plenum chamber.