Apparatus for removing particles from a gaseous stream

Claim 1

A filter for removing particles from a gaseous stream comprising, a solid elongated shaft including at least two outer surfaces each being defined by an upstanding strip extending substantially the entire length of the shaft and disposed in a plurality of spaced apart helical turns to define at least two continuous helical grooves; a first hollow elongated tube of about the same length as the shaft and including an inner surface and an outer surface, the inner surface of the first tube being substantially smooth and complementary in cross-section to the outer surface of the shaft, the shaft being slideably and snugly received within the first tube and the helical grooves of the shaft constituting a first continuous helical conduit, the outer surface of the first tube being defined by at least two upstanding strips extending substantially the entire length of the first tube and disposed in a plurality of spaced apart helical turns to define continuous helical grooves; a second hollow elongated tube of about the same length as the first tube and including an inner surface and an outer surface, the inner surface of the second tube being substantially smooth and complementary in cross-section to the outer surface of the first tube, the first tube being slideably and snugly received within the second tube and the helical grooves of the first tube constituting a second continuous helical conduit concentric with the first conduit, the outer surface of the second tube being defined by at least two upstanding strips extending substantially the entire length of the second tube and disposed in a plurality of spaced apart helical turns to define at least two continuous helical grooves; a hollow elongated tubular sheath of about the same length as the second tube and including an inner surface, the inner surface of the sheath being substantially smooth and complementary to the cross-section of the outer surface of the second tube, the second tube being slideably and snugly received within the sheath and the helical grooves of the second tube constituting a third plurality of continuous helical conduits concentric with the first and second conduits, wherein the respective surfaces of each helical groove of the shaft and tubes are roughened and wherein the shaft is slideably removable from within the first tube, the first tube is slideably removable from within the second tube and the second tube is slideably removable within the sheath wherein a gaseous stream having particles suspended therein is divided and directed simultaneously into and through the concentric conduits and is constrained within a plurality of helical pathways to remove by centrifugal force a large number of the particles from the gaseous stream.