Ejector hood
An ejection hood apparatus includes a transfer conduit and a hood. The transfer conduit includes a downwardly concave control shell. An inlet end portion of the transfer conduit receives an upwardly directed transfer air stream including ejected material with at least a partially upward trajectory. The hood defines an ejection chamber including a lower chamber portion and an upper chamber portion. The lower chamber portion receives the transfer air stream from an outlet end portion of the transfer conduit with at least a partially downward trajectory. The hood includes at least one air outlet passage communicated with the upper chamber portion for exhausting at least a portion of the transfer air stream.
1. A method of transferring material, the method comprising the steps of:
(a) providing on a conveyor a stream of material to be sorted;
(b) launching the stream of material off of the conveyor thus creating an airborne stream of material;
(c) ejecting material from the airborne stream of material with a nozzle array directed at least partially upwardly thereby creating a transfer air stream including entrained material;
(d) directing the transfer air stream at least partially downwardly through a chamber inlet into a receiving chamber;
(e) creating a swirling air flow of the transfer air stream in the receiving chamber so that the swirling air flow does not flow back through the chamber inlet;
(f) dropping entrained material out of the swirling air flow downward through a chamber outlet; and
(g) relieving at least some of the swirling air flow through an airflow outlet defined in an upper portion of the receiving chamber.
2. The method of claim 1 , wherein:
in step (d) the transfer air stream is directed downwardly and laterally through the chamber inlet into the receiving chamber.
3. The method of claim 1 , wherein:
the transfer air stream is at least partially deflected from an outlet conveyor located below the chamber outlet back up into the upper portion of the receiving chamber thereby creating the swirling air flow in the upper portion of the receiving chamber above the outlet conveyor so that entrained material caught up in the swirling air flow drops back down onto the outlet conveyor without being blown back through the chamber inlet.
4. The method of claim 1 , wherein:
in step (g) the upper portion of the receiving chamber is defined by a hood, and the airflow outlet is defined by a plurality of perforations in the hood.
5. The method of claim 1 , wherein:
in step (g) the upper portion of the receiving chamber is defined by a hood, and the airflow outlet is defined by an exhaust duct communicated with the hood.
6. The method of claim 1 , wherein:
step (d) further comprises directing the transfer air stream including the ejected relatively lightweight material with a transfer conduit, the transfer conduit including:
a downwardly concave control shell, the control shell being impervious to air so that there is no air flow across the control shell; and
a conduit floor located below the control shell and sloped downwardly toward the ejection chamber, the conduit floor and control shell at least in part defining a conduit outlet communicated with the chamber inlet.