Air/particle separator

• US 20040103785A1
• Filed: 12/30/2002
• Published: 06/03/2004
• Est. Priority Date: 07/06/2000
• Status: Active Grant

• Current Assignee: John Herbert North
• Original Assignee: John Herbert North
• Inventors: North, John Herbert
• Granted Patent: US 6,936,095 B2
• Time in Patent Office: Days
• US Class Current: 95/271
• CPC Class Codes: A47L 9/1608 Cyclonic chamber constructions
• CPC Class Codes: A47L 9/1625 for series flow
• CPC Class Codes: A47L 9/165 Construction of inlets
• CPC Class Codes: A47L 9/1658 Construction of outlets
• CPC Class Codes: A47L 9/19 Means for monitoring filtering operation
• CPC Class Codes: B01D 45/12 by centrifugal forces centrifuges B04B; cyclones B04C
• CPC Class Codes: B01D 45/14 generated by rotating vanes, discs, drums or brushes
• CPC Class Codes: B01D 45/16 generated by the winding course of the gas stream , the centrifugal forces being generated solely or partly by mechanical means, e.g. fixed swirl vanes
• CPC Class Codes: B04C 11/00 Accessories, e.g. safety or control devices, not otherwise provided for , e.g. regulators, valves in inlet or overflow ductingwith electrostatic precipitating arrangements B03C3/14
• CPC Class Codes: B04C 3/00 Apparatus in which the axial direction of the vortex flow following a screw-thread type line remains unchanged ; Devices in which one of the two discharge ducts returns centrally through the vortex chamber, a reverse-flow vortex being prevented by bulkheads in the central discharge duct combined with other devices B04C9/00
• CPC Class Codes: B04C 3/04 Multiple arrangement thereof combined with types according to other groups, B04C7/00
• CPC Class Codes: B04C 5/103 Bodies or members, e.g. bulkheads, guides, in the vortex chamber cores B04C5/107
• CPC Class Codes: B04C 5/13 formed as a vortex finder and extending into the vortex chamber exits with bulkheads preventing reverse flow vortex B04C3/00; Discharge from vortex finder otherwise than at the top of the cyclone; Devices for controlling the overflow
• CPC Class Codes: B04C 5/15 with swinging flaps or revolving sluices; Sluices; Check-valves
• CPC Class Codes: B04C 5/185 Dust collectors
• CPC Class Codes: B04C 5/26 for series flow
• CPC Class Codes: B04C 5/30 Recirculation constructions in or with cyclones which accomplish a partial recirculation of the medium, e.g. by means of conduits
• CPC Class Codes: B04C 7/00 Apparatus not provided for in group B04C1/00, B04C3/00, or B04C5/00; Multiple arrangements not provided for in one of the groups B04C1/00, B04C3/00, or B04C5/00; Combinations of apparatus covered by two or more of the groups B04C1/00, B04C3/00, or B04C5/00
• CPC Class Codes: Y10S 55/03 Vacuum cleaner

Abstract

A method of separating particles from particle laden air is described. The apparatus employed is a multiple stage separator in which the first stage comprises a generally cylindrical chamber (18) having a hollow central member (50) extending axially from one end thereof with openings (53) in its wall remote from the said one end. The first separation step is achieved by introducing air tangentially into the chamber (18) near its said one end, the tangential entry in combination with an unapertured region of the wall of the central member (50) establishing a rotating mass of air in the chamber, thereby causing heavier than air particles to migrate to the outer regions of the chamber (18) under centrifugal force. Suction is applied to the interior of the central member (50) to cause an axial movement of air through the chamber before it can exit through the openings (53) in the wall of the central member (50). The suction force is selected such that particles near the walls of the chamber tend to continue in a generally rotational and axially progressive path into a particle collecting regions of the chamber (26), while relatively particle-free air is drawn radially inwardly, as it progresses axially, so as to exit to a second separation stage, through the openings in the central member wall.

Claims

1. A method of separating particles from particle laden air by means of a multiple stage separator in which the first stage comprises a generally cylindrical chamber having a hollow central member extending from one end axially thereof and which includes openings in the wall of the central member remote from the said one end, wherein the first stage separation is achieved by:

1) introducing air tangentially into the chamber near the said one end thereof, the tangential entry in combination with an unapertured region of the wall of the central member establishing a rotating mass of air in the chamber, thereby causing heavier than air particles to migrate to the outer regions of the chamber under centrifugal force;

2) establishing an axial migration of the rotating mass of air by applying suction to the interior of the central member to cause an axial movement of air through the chamber before it can exit through the openings in the wall of the central member; and

3) selecting the suction force such that particles near the walls of the chamber will tend to continue in a generally rotational and axially progressive path into a particle collecting region of the chamber, while relatively particle-free air will be drawn radially inwardly, as it progresses axially, so as to exit to a second separation stage, through the openings in the central member wall.

2. A multi-stage particle/air separator for performing the method of claim 1 comprising:

(1) a first stage comprising a cylindrical chamber, from one end of which internally extends a central member having openings 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.

3. Apparatus as claimed in claim 2 wherein the apertured region of the central member is a hemispherical (52) or frusto-conical (52′

) hollow shell which extends from the unapertured cylindrical region thereof towards the said other end of the chamber.

4. Apparatus as claimed in claim 2 or 3 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.

5. Apparatus as claimed in claim 4 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.

6. Apparatus as claimed in any of claims 2 to 5 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.

7. Apparatus as claimed in claim 6 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.

8. Apparatus as claimed in claim 7 in which the valve means is a ball valve and wherein the ball is lifted to close the valve by airflow established through the apparatus by the suction effect.

9. Apparatus as claimed in claim 8 wherein the axial distance between the exit end of the passage in the central member and the ball, when the valve is closed, is of the order of 52 mm.

10. Apparatus as claimed in claim 7 in which the valve means includes a closure member which is held in an open condition by spring means.

11. Apparatus as claimed in the claim 10 in which the closure member is a poppet so as to reduce the axial length of the valve housing.

12. Apparatus as claimed in claim 11 in which the poppet includes a flat plate which moves nearer to and further away from the exit end of the central passage as the poppet moves between its closed and open positions.

14. Apparatus as claimed in claim 6 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.

15. Apparatus as claimed in claim 14 wherein the separate particle collecting region is formed by a tubular member extending centrally of the chamber from the lower end of the said central member towards and sealingly engaging with the far end of the chamber, so as to define with the wall of the far end of the chamber an annular region which comprises the particle collecting region of the first stage, and a separate inner region for collecting particles from the later stage.

16. Apparatus as claimed in claim 15 wherein the tubular member is separable from the end wall of the chamber.

17. Apparatus as claimed in claim 15 or 16 wherein the cylindrical chamber is formed in two parts, a first part comprising a cylindrical region surrounding the central member and extending axially substantially to the same extent as the said central member, and a second part which can be sealingly joined to and in axial alignment with the first part to form an enclosure and which includes a closed end which is engaged by the free end of the tubular member to form the separate dust collecting chamber.

18. Apparatus as claimed in any of claims 2 to 17 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 enter.

19. Apparatus as claimed in claim 18 wherein 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.

20. Apparatus as claimed in claim 19 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.

21. Apparatus as claimed in claim 20 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.

22. Apparatus as claimed in claim 20 or 21 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.

23. Apparatus as claimed in claim 20, 21 or 22 wherein the central member comprises a vortex initiator for air entering the said second chamber.

24. Apparatus as claimed in any of claims 20 to 23 wherein the entrance to the second chamber is near the end thereof which is furthest from the fist chamber.

25. Apparatus as claimed in any of claims 20 to 24 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.

26. Apparatus as claimed in claim 24 or 25 in which the helical flange comprises less than one complete turn, or one complete turn, more than one turn or a plurality of complete turns.

27. Apparatus as claimed in any of claims 20 to 26 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.

28. Apparatus as claimed in claim 27, wherein the turbine comprises at least two sections which are axially spaced with the blades of one section out of phase with the blades of the other.

29. Apparatus as claimed in claim 27 or 28, wherein the turbine is secured to the said hollow central member, and the latter is rotatable within the second chamber.

30. Apparatus as claimed in any of the preceding claims 19 to 29, 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.

31. Apparatus as claimed in claim 30 wherein the included angle of the cone of which the frusto conical surface forms part, lies in the range 100-140 degrees preferably 120 degrees.

32. Apparatus as claimed in claim 30 or 31 wherein the second chamber includes a third region extedning 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.

33. Apparatus as claimed in any of claims 2 to 32 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.

34. Apparats as claimed in claim 33 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.

35. Apparatus as claimed in the claim 34 in which the third stage is a generally cylindrical chamber.

36. Apparatus as claimed in claim 34 or 35 wherein air enters the third stage generally centrally of one end of the chamber

37. Apparatus as claimed in claim 36 in which 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.

38. Apparatus as claimed in claim 37 wherein the deflector comprises a conical lower end of the central member in the third stage, whose apex points towards the incoming airstream.

39. Apparatus as claimed in claim 36, 37 or 38 wherein a helix extends around the central member to introduce rotational and axial movement 6f the airflow through the third stage and the second outlet is located axially beyond the exit end of the helix.

40. Apparatus as claimed in any of claims 37 to 39 wherein the first outlet comprises a plurality of small openings in the wall of the central member in the third stage.

41. Apparatus as claimed in claims 34, 35 or 36 in so far as they depend from claims 27, 28 or 29 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 outlet.

42. Apparatus as claimed in any of claims 37 to 41 in which the second outlet communicates via a passage with a second inlet in the wall of the second stage chamber.

43. Apparatus as claimed in claim 42 wherein the second outlet in the second stage wall 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.

44. Apparatus as claimed in claim 42 wherein the rotation of the air in the second chamber generates a suction effect at the second inlet supplied with air from the third chamber, the suction effect being at least as great as, and preferably greater than, the suction effect at the said first outlet in the third stage.

45. Apparatus as claimed in any of claims 37 to 44 wherein an apertured sleeve or gauze surrounds at least part of the central member in the third stage to reduce the chance of particles which have been deflected therethrough from returning to leave the third stage chamber via the first outlet.

46. Apparatus as claimed in any of claims 2 to 45 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.

13. Apparatus as claimed in claim wherein 11 the distance between the plate and the exit end of the central passage, when the valve is closed, is of the order of 4 mm.

47. Apparatus constructed arranged and adapted to operate substantially as herein described or as illustrated and described with reference to the accompanying drawings.

48. A method of separating particles from particle-laden air substantially as herein described or as illustrated and described with reference to the accompanying drawings.