Apparatus for classifying the constituents of a pneumatically conveyed tobacco-containing stream

Claim 1

Apparatus for classifying the contents of a stream including larger and smaller particles wherein at least the larger particles consist of tobacco, comprising a pneumatic conveyor arranged to transport a stream of particles and a gaseous carrier medium along a predetermined path and having a discharge end; a gas separating device at one side of and communicating with said discharge end to withdraw at least the major part of the carrier medium from said path but to allow the particles to remain in said path; a classifying duct communicating with said discharge end independently of the communication between said discharge end and said separating device to receive the particles from said path and having a perforated wall extending transversely of said discharge end and arranged to intercept said larger particles while permitting the smaller particles to pass therethrough, said wall being disposed opposite said discharge end so that the larger particles enter said duct from said path and are intercepted by said wall; means for evacuating the larger particles from said duct, said separating device comprising a rotary separator located at a level above said wall and said evacuating means, said discharge end of said pneumatic conveyor being substantially tangential to and adjacent said rotary separator; and means for varying the cross-sectional area of said discharge end, including a member immediately adjacent to said gas separating device and extending into said duct.