WO1999062640A1

WO1999062640A1 - Centrifuge separator

Info

Publication number: WO1999062640A1
Application number: PCT/GB1999/001690
Authority: WO
Inventors: Nicholas Syred; Andrew Hitchings
Original assignee: University College Cardiff Consultants Limited
Priority date: 1998-05-29
Filing date: 1999-05-27
Publication date: 1999-12-09
Also published as: GB9811455D0; AU4155299A

Abstract

A centrifuge separator comprises a centrifuge tube (12) which is driven in a predetermined direction of rotation (B) around its longitudinal axis, whilst particle-laden gas or other fluid is introduced into one end (12a) of the tube (12) via inlet means (24) and as a rotary flow, the direction of which is opposite to the direction of rotation (B) of the tube (12). An outlet means (28, 30, 32) for clean fluid is mounted at the opposite end (12b) of the tube (12); an outlet means (26) for particle-laden fluid is mounted at the inlet end (12a) of the tube (12) and is arranged for the particle-laden fluid to pass out of the separator as a rotary flow in a direction corresponding to the direction of rotation of the tube (12).

Description

Centrifuge separator

The present invention relates to a centrifuge separator, particularly but not solely for separating out particles suspended in a gas.

Centrifuge separators are known which comprise a centrifuge tube mounted for rotation about its longitudinal axis, and provided with drive means (e.g. a turbine arrangement) for turning the tube in a predetermined direction of rotation. Separators of this type have been proposed with various different arrangements for the inlet of particle laden gas and the separate outlet of "clean" gas and "dirty" gas. In one form of separator, the inlet gas enters one end of the centrifuge tube, passes along this tube, generally at and adjacent its axis, then part of the gas undergoes a reversal to flow back along the centrifuge tube adjacent its inner surface: this part of the gas issues from the separator at the inlet end of centrifuge tube as the "dirty gas" outlet; the remaining part of the gas does not undergo a reversal within the centrifuge tube but instead issues from the opposite end of this tube, as clean gas. We have now modified the above-described separator with the result of substantially improving its performance.

Thus, in accordance with the present invention, there is provided a centrifuge separator which comprises a centrifuge tube mounted for rotation about its longitudinal axis, drive means for rotating the centrifuge tube in a predetermined direction of rotation around its said axis, inlet means mounted at an inlet end of the centrifuge tube and arranged for introducing particle-laden fluid into the centrifuge tube as a rotary flow, the direction of rotary flow of the inlet fluid being opposite to the direction of rotation of the centrifuge tube, a primary outlet means for clean fluid mounted at an opposite, outlet end of the centrifuge tube, and a secondary outlet means for particle-laden fluid mounted at said inlet end of the centrifuge tube and arranged for the outlet of particle- laden gas as a rotary flow in a direction corresponding to the direction of rotation of the centrifuge tube. In use of this separator, we find that the major part of the inlet fluid (particularly gas) passes out of the primary outlet substantially free of particles, whilst the remaining, minor part of the inlet fluid undergoes a reversal of its flow direction within the centrifuge tube, to flow from the secondary outlet laden with particles.

We have in particular found it surprising that the performance of the separator is substantially better with the inlet fluid introduced in a rotary direction opposite to, rather than the same as, the direction of rotation of the centrifuge tube: the logical expectation would be that the inlet fluid should be introduced in the rotary direction corresponding to the direction of rotation of the centrifuge tube. Preferably a cruciform is provided in the outlet end of the centrifuge tube, to assist in pumping the particle-free part of the fluid out through the primary outlet means.

Preferably the inlet means comprises a toroidal duct having a tangential inlet port into which, in use, the inlet fluid is introduced, this toroidal duct communicating with the inlet end of the centrifuge tube.

Preferably the secondary outlet means comprises a toroidal duct having a tangential outlet port out of which, in use, the dirty fluid passes. Preferably the primary outlet means is arranged for the clean fluid to pass out of the separator as a rotary flow: preferably, in order to maximise the throughput of the separator, the rotary direction of this rotary flow corresponds to the direction of rotation of the centrifuge tube. Preferably the primary outlet means comprises a toroidal duct having a tangential outlet port.

An embodiment of the present invention will now be described by way of example only and with reference to the accompanying drawings, in which: FIGURE 1 is a diagrammatic longitudinal section through a centrifuge separator in accordance with the present invention; and

FIGURE 2 is a schematic, isometric view of the centrifuge separator of Figure 1. Referring to the drawings, there is shown a centrifuge separator which comprises a tubular housing 10 in which -a centrifuge tube 12 is mounted on bearings 14,16 for rotation around its longitudinal axis. Drive means are provided for rotating the centrifuge tube 12: these drive means may take any convenient form but are indicated diagrammatically in Figure 1 as a turbine 18 coupled to the centrifuge tube 12.

A manifold assembly 20 is mounted to one end 10a of the tubular housing 10. The manifold assembly 20 has a central, axial passage 22 communicating with the corresponding end 12a of the centrifuge tube 12 and in turn communicating with first and second toroidal ducts 24,26. An outlet assembly 28 is mounted to the opposite end 10b of the tubular housing 10 and has a central, axial passage 30 communicating with the corresponding end 12b of the centrifuge tube 12 and with a toroidal duct 32.

Referring to Figure 2, the first toroidal duct 24 is provided with a tangential extension 24a forming an inlet port for gas or other fluid in which particles are suspended. This gas therefore enters the toroidal duct 24 tangentially and flows around this duct, and spirally inwardly to the central passage 22, in the rotary direction indicated by the arrow A. The centrifuge tube 12 is driven in the opposite rotary direction, as indicated by the arrow B. The inlet gas passes axially into and along the rotary centrifuge tube 12, from right to left as viewed in Figure 1. Part of the gas, with its suspended particles, reverses direction and flows back towards the inlet end of the centrifuge tube 12, adjacent its inner surface. This returned flow of gas passes, in spiral manner, into the toroidal duct 26 and finally out from this toroidal duct via a tangential extension 26a as indicated by the arrow C: the rotary direction of gas flow into, around and out of the toroidal duct 26 corresponds to the direction of rotation B of the centrifuge tube 12 and is accordingly opposite to the rotary direction of gas flow in the inlet toroidal duct 24.

Whilst gas laden with the suspended particles follows the reversed or return path within the centrifuge tube 12, as just described, the remaining part of the gas, freed of suspended particles, flows out of the left hand or outlet end of the centrifuge tube 12, into the axial passage 30 of the outlet assembly 28. From here, this clean gas flows in outwardly-spiralling manner into, around and finally out of the toroidal duct 32 via a tangential extension as indicated by the arrow D: it will be noted that the rotary direction of flow D through this toroidal duct corresponds to the direction of rotation of the centrifuge tube 12. The outlet end of the rotating centrifuge tube 12 is provided with a cruciform 34, which assists in pumping the particle-free part of the gas out through the outlet assembly 28.

Preferably the outlet ports 26a and 32a are provided with portions (not shown) which diverge (i.e. increase in cross-section in the downstream direction) to reduce the pressure drop developed in these ports, in use of the separator.

We have found that the separator which has been described is highly effective in separating out particles from the inlet gas. A major part of the inlet gas flow out of the primary outlet port 32a as clean gas, substantially free of particles, whilst the remaining, minor part of the inlet gas flows out of the dirty gas outlet port 26a.

SUBSTΓΓUTE SHEET (RULE 26)

Claims

1) A centrifuge separator which comprises a centrifuge tube (12) mounted for rotation about its longitudinal axis, drive means (18) for rotating the centrifuge tube (12) in a predetermined direction of rotation (B) around its said axis, inlet means (24a, 24) mounted at an inlet end (12a) of said centrifuge tube (12) and arranged for introducing particle- laden fluid into the centrifuge tube (12) as a rotary flow, the direction (A) of rotary flow of the inlet fluid being opposite to the direction of rotation (B) of the centrifuge tube (12) , a primary outlet means (32,32a) for clean fluid mounted at an opposite, outlet end (12b) of the centrifuge tube (12), and a secondary outlet means (26,26a) for particle-laden fluid mounted at said inlet end (12a) of the centrifuge tube (12) and arranged for the outlet of particle-laden fluid as a rotary flow in a direction (c) corresponding to the direction of rotation (B) of the centrifuge tube (12) .

2) A centrifuge separator as claimed in claim 1, in which said inlet means comprises a toroidal duct (24) having a tangential inlet port (24a) into which, in use, said inlet fluid is introduced, said toroidal duct (24) communicating with said inlet end (12a) of the centrifuge tube (12).

3) A centrifuge separator as claimed in claim 1 or 2 , in which said secondary outlet means comprises a toroidal duct (26) having a tangential outlet port (26a) out of which, in use, particle-laden fluid passes.

4) A centrifuge separator as claimed in claim 3, in which said tangential outlet port (26a) is provided with a portion which increases in cross-section in this downstream direction.

5) A centrifuge separator as claimed in any preceding claim, in which said primary outlet means (32, 32a) is arranged for said clean fluid to pass out of the separator in a rotary flow. 6) A centrifuge separator as claimed in claim 5, in which said primary outlet means (32, 32a) is arranged for the direction (D) of said rotary flow of said clean fluid to correspond to the direction of rotation (B) of the centrifuge tube (12) .

7) A centrifuge separator as claimed in claim 6, in which said primary outlet means comprises a toroidal duct (32) having a tangential outlet port (32a) .

8) A centrifuge separator as claimed in claim 7, in which said tangential port (32a) of said primary outlet means is provided with a portion which increases in cross-section in the downstream direction.

9) A centrifuge separator as claimed in any preceding claim, in which said centrifuge tube (12) is provided, at its said outlet end (12b) , with a cruciform (34) to assist in pumping the clean fluid out through said primary outlet means.

10) A method of separating out particles suspended in a fluid, the method comprising the steps of providing a centrifuge tube (12) , rotating said centrifuge tube (12) in a predetermined direction of rotation (B) around its longitudinal axis, introducing particle-laden fluid into the centrifuge tube (12) at an inlet end (12a) thereof as a rotary flow, the direction (A) of said rotary flow of the inlet fluid being opposite to the direction of rotation (B) of the centrifuge tube (12), causing or permitting clean fluid to pass out of said centrifuge tube (12) at an opposite end (12b) thereof, and causing or permitting particle-laden fluid to pass out of said centrifuge tube (12) at said inlet end (12a) thereof as a rotary flow the direction (C) of which corresponds to the direction of rotation (B) of the centrifuge tube (12).