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A method of separating particles from particle laden air having a multiple stage separator in which the first stage comprises a generally cylindrical chamber having a hollow central member extending axially from one end thereof with openings in its wall remote from the one end. The first separation

A method of separating particles from particle laden air having a multiple stage separator in which the first stage comprises a generally cylindrical chamber having a hollow central member extending axially from one end thereof with openings in its wall remote from the one end. The first separation step is achieved by introducing air tangentially into the chamber near its one end, establishing a rotating mass of air in the chamber causing heavier than air particles to migrate to the outer regions of the chamber. Suction is applied to the interior of the central member to cause an axial movement of air through the chamber such that particles near the walls of the chamber tend to continue in a generally rotational and axially progressive path into a particle collecting region of the chamber, while relatively particle-free air is drawn radially inwardly.

대표청구항 ▼

1. 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

1. 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 downstream of the separation stages 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) the apertured region of the central member is a hemispherical or frusto-conical hollow shell which extends from the unapertured cylindrical region thereof towards the said other end of the chamber. 2. Apparatus as claimed in claim 1 wherein a skirt extends from the end of the central member beyond the region containing the openings in the wall thereof, to define a narrow annular gap between the skirt and the wall of the chamber, so that particles in the dust collecting region which due to turbulence may rise up in the region towards the central member, are prevented from reaching the openings therein unless they migrate radially outwardly to pass through the narrow annular gap against the flow of the incoming particles.3. Apparatus as claimed in claim 2 wherein an annular flange is provided around the central member between the unapertured and apertured regions of the wall thereof, so as to force the vortex of rotating air within the chamber away from the central member as it progresses along the chamber.4. Apparatus as claimed in claim 1 wherein particles. separated in a later separation stage are conveyed to a particle collecting region via a passage extending through the central member of the first stage.5. Apparatus as claimed in claim 4 in which the passage communicates with the particle collecting region, of the cylindrical chamber of the first stage via valve means which is closed during air flow through the apparatus, and is opened after air flow ceases to allow particles collected upstream of the valve to pass into the particle collecting region of the chamber of the first stage.6. Apparatus as claimed in claim 5 in which the valve means includes a closure member which is held in an open condition by spring means.7. Apparatus as claimed in claim 4 in which the passage communicates with a particle collecting region, which is separate from the first stage particle collecting region, so that particles separated by the first stage are collected separately from particles separated by the later stage, of the multiple stage separator.8. Apparatus as claimed of claim 1 wherein 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, and the second cylindrical chamber is located downstream of the first chamber and is situated beyond the said one end of the first chamber, remote from the dust collecting region of the latter.9. Apparatus as claimed in claim 8 wherein the entrance in the second cylindrical chamber causes air to enter the chamber tangentially and the chamber includes a hollow central member which extends axially thereof over at least part of its length from the end thereof furthest from the first chamber.10. Apparatus as claimed in claim 9 wherein the free end of the hollow central member includes at least one opening therein to provide an outlet for air and any remaining particles to exit from the second chamber.11. Apparatus as claimed in claim 9 wherein the free end of the hollow central member is closed but the wall of the central member has apertures therein through which air and any remaining particles can exit from the said second chamber.12. Apparatus as claimed in claim 9 wherein a helical flange protrudes from the central member, thereby forcing circulating air in the second chamber to describe a helical path as it passes from one end of the chamber towards the other.13. Apparatus as claimed in claim 9 wherein a rotatable turbine is located in the second chamber for rotation about the chamber axis, and the blades of the turbine are aligned relative to the entrance in the second chamber so that the incoming tangential airstream produces rotation thereof.14. Apparatus as claimed in claim 8 wherein 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.15. Apparatus as claimed in claim 14 wherein 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.16. 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. 17. Apparatus as claimed in claim 16 wherein the included angle of the cone of which the frusto-conical surface if the second region of the second chamber forms a part lies in the range 100-140 degrees.18. Apparatus as claimed in claim 1 which further includes a third stage located downstream from the second stage, for separating any particles remaining in the airstream which passes from the second stage to the third stage.19. Apparatus as claimed in claim 18 wherein the central passage of the second stage communicates with the third stage to allow air to pass into the third stage from the second stage, the third stage is a generally cylindrical chamber, air enters the third stage generally centrally of one end of the chamber, the third stage includes a hollow central member and has a first outlet in the wall of the central member and a second outlet in the wall of the chamber, and a deflector is provided in the third stage to cause air entering the chamber to move radially outwardly so that any particles remaining in the air stream are radially displaced away from the centre of the chamber and axially away from the first outlet, in a direction to enter the second outlet.20. Apparatus as claimed in claim 19 wherein the deflector comprises a conical lower end of the central member in the third stage, whose apex points towards the incoming airstream.21. Apparatus as claimed in claim 19 wherein a helix extends around the central member to introduce rotational and axial movement of the airflow through the third stage and the second outlet is located axially beyond the exit end of the helix.22. Apparatus as claimed in claim 19 wherein the first outlet comprises a plurality of small openings in the wall of the central member in the third stage.23. Apparatus as claimed in claim 13 in which further includes a third stage located downstream from the second stage, for separating any particles remaining in the airstream which passes from the second stage to the third stage, and wherein the central passage of the second stage communicates with the third stage to allow air to pass into the third stage from the second stage, the third stage is a generally cylindrical chamber, air enters the third stage generally centrally of one end of the chamber, the third stage includes a hollow central member and has a first outlet in the wall of the central member and a second outlet in the wall of the chamber, and a deflector is provided in the third stage to cause air entering the chamber to move radially outwardly so that any particles remaining in the air stream are radially displaced away from the centre of the chamber and axially away from the first outlet, in a direction to enter the second outlet, and wherein the third stage includes a hollow rotary central member driven by the turbine in the second stage for imparting rotational motion to the incoming air stream entering the third stage and thereby causing particles remaining in the air entering the third stage to migrate outwardly under centrifugal force, and a second outlet in the third stage is located so as to collect any such particles for return to an earlier separation stage, and a first outlet is located at the opposite end of the chamber from the end in which the incoming air enters, so that after being rotated the air has to change direction and move axially through the chamber before it can leave via the first output.24. Apparatus as claimed in claim 23 in which the second outlet communicates via a passage with a second inlet in the wall of the second stage chamber, which causes air entering the second stage chamber to do so tangentially of the chamber and in the same direction as the air is rotating in the second stage chamber.25. Apparatus as claimed in Maim 1 further including level detection means in a particle collecting region to initiate an alarm in the event that the particles collected therein exceed a given volume.