Conveyor tunnel

A tunnel system for impinging process air against articles moving through the tunnel, said tunnel system comprising:

• a conveyor extending along a conveyor path;
• a pair of first and second plenums on opposite sides of the conveyor path and extending along at least a portion of the conveyor path;
• opposed top and bottom walls extending between the first and second plenums, the top and bottom walls and the first and second plenums defining a tunnel surrounding and extending along said at least a portion of the conveyor path;
• each plenum defining an interior to receive process air and comprising a first wall facing the conveyor path, a set of intake openings in fluid communication with the interior, a first set of discharge openings in the first wall in fluid communication with the interior of the plenum, and a first set of louvers attached to the plenum, the first set of discharge openings spaced apart along the conveyor path, each louver associated with a respective discharge opening and defining the flow direction of process air discharged into the tunnel through the associated discharge opening, the first set of louvers comprising vanes defining the flow channels, the vanes being movable with respect to the louvers wherein the direction of the flow channels can be selectively varied, the vanes being movable to a position wherein the flow channels extend from the first wall away from the first wall;
• and
• one of the said top and bottom walls comprising a set of exhaust openings extending through the said one wall and spaced apart along the conveyor path, each exhaust opening in fluid communication with the interior of the tunnel.