Air/particle separator

A multi-stage particle/air separator for separating particles from particle laden air comprising:

• (1) a first stage comprising a cylindrical chamber, from one end of which internally extends a central member having apertures in the wall thereof remote from the said one end;
• (2) an air inlet in the chamber wall by which particle laden air enters the chamber tangentially near the said one end thereof;
• (3) a second dust/air separation stage to which air from the first stage chamber can pass via the openings in the wall of the central member;
• (4) suction means for inducing air flow from the first stage to the second stage;
• (5) a particle collecting region at the end of the chamber remote from the said one end, into which the particles migrate as a result of being separated from the air passing into the central member;
• (6) that part of the central member adjacent the said one end of the chamber being cylindrical and unapertured and in combination with the cylindrical chamber defining an annular region therein, adjacent the air inlet thereto;
• (7) the annular region around the unapertured cylindrical region of the central member, and the incoming tangential airstream, combining to initiate a vortex within the chamber, so that incoming air is formed into a rotating mass of air in the chamber at the said one end thereof whereby centrifugal force causes heavier than air particles in the incoming air to migrate to the outer regions of the chamber, the suction causing axial migration of the rotating mass of air from the said one end of the chamber towards the other end thereof;
• (8) the suction force being selected so that heavier than air particles will tend to remain in the radially outer regions of the chamber near the wall of the chamber as they progress rotationally and axially along the chamber towards the particle collecting region while relatively particle free air will migrate radially inwardly to exit through the openings in the wall of the central member, wherein
• (9) a passage extends through the central member from the openings in the wall thereof to an entrance in a second cylindrical chamber forming part of a second separation stage, through which air and any particles remaining therein pass from the first stage to the second stage,
• (10) the said second chamber includes a first generally cylindrical region and a second region extending therefrom which is frusto conical and whose diameter progressively reduces from that of the cylindrical region in a direction away therefrom, and
• (11) the second chamber includes a third region extending beyond the first frusto conical region, which is also frusto conical, but in which the diameter progressively reduces more slowly with axial distance from the cylindrical region than does the diameter of the first frusto conical region.