Air/particle separator

Claim 2

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.

Claim 3

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.

Claim 4

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.

Claim 5

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.

Claim 6

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.

Claim 7

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.

Claim 8

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.

Claim 9

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.

Claim 10

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.

Claim 11

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.

Claim 12

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.

Claim 13

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.

Claim 14

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.

Claim 15

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.

Claim 16

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.

Claim 17

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

Claim 18

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.

Claim 19

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.

Claim 20

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.

Claim 21

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.

Claim 22

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.

Claim 23

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.

Claim 24

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.

Claim 25

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.

Claim 26

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.

Claim 27

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.

Claim 28

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.

Claim 29

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.

Claim 30

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.

Claim 31

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.

Claim 32

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.

Claim 33

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.

Claim 34

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.

Claim 35

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.

Claim 36

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

Claim 37

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

Claim 38

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.

Claim 39

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.

Claim 40

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

Claim 41

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.

Claim 42

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.

Claim 43

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.

Claim 44

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.

Claim 45

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.

Claim 46

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.

Claim 47

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.

Claim 48

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

Claim 49

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

Claim 50

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.

Claim 51

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.