GB2055310A - Apparatus for separating particles from a gas stream - Google Patents

Abstract

Particle separating apparatus comprises two centrifugal, e.g. cyclonic, separators (10, 18), connected by a pipe (15). The pipe (15) contains flow straightening and smoothing devices comprising vanes (16) and a gauze plate (17). <IMAGE>

Description

SPECIFICATION Apparatus for removing particles from a gas stream This invention relates to apparatus for removing particles from a gas stream.

One well known method of removing particles from gas streams involves the use of cyclones or other forms of centrifugal separators. In general these separators cause the air to flow at a circular or helical path so that particles are centrifuged to the outside of the path where they can be corrected and the clean air may be removed from the centre of the circle or helix. It might be expected that if two such devices were operated in series then a conventional improvement would be obtained in the cleanliness of the exhaust gas.

However, in tests which we have carried out we have found that a surprising number of particles some which are relatively large can continue to be entrained in gas even when it has passed through two or three stages of centrifugal separation. We believe that this problem is due to the presence in the exhaust gas from each separator of pockets of gas having relatively low energy. These pockets then pass through suceeding separator stages without sufficient deviation from their path to provide any substantial centrifugal separation.

The present invention provides separation apparatus in which this problem is reached.

According to the present invention apparatus for separating particles from a gas comprises at least two centrifugal separators mounted in series and flow smoothing rings mounted in gas flow between the separators, the flow smoothing rings being adapted to improve the homogeneity of a gas flow.

The flow smoothing rings may for instance comprise flow straightening vanes and or a perforated gauze or other restrictor device through which the gas must flow.

The invention will now be particularly described with reference to the accompanying drawing which is a schematic view of a system in accordance with the invention.

In the drawing there is shown a conventional cyclone 10 having an inlet 11 into which a particle carrying gas is fed. Within the cyclone the gas is caused to flow in a helical fashion indicated at 10 with the result that at least the majority of the particles carried by the gas are centrifuged outwardly against the side of the cyclone. These particles then fall under gravity and are collected in a manifold 1 3 to be led away through a waste duct 14.

The clean gas escapes from a cyclone through a central passage 1 5. It will be understood that because of the helical movement of the gas within the cyclone the exhaust gas in the pipe 1 5 will flow in a relatively turbulent fashion and will therefore include regions of relatively low energy. As explained above these regions are likely to reduce the effect of subsequent stages of centrifugal separation. Therefore in accordance with the invention a series of flow straightening vanes are provided through which the gas flows. These vanes improve the linearity of the flow which then passes through a gauze plate 1 7. The pressure drop across the plate enables any remaining irregularities in the flow to be reduced to removed altogether.The smooth gas is then allowed to flow into a second cyclone 1 8 which is identical to the cyclone 10 and therefore not described therein.

It will be understood that although the flow straightening vanes 1 6 and gauze plates 1 7 are convenient devices to use it will be possible to use various other means for improving the smoothness and homogeneity of the flow.

1. Apparatus for separating particles from a gas comprising at least two centrifugal separators mounted in series and flow separating rings mounted in a gas flow between the separators, the flow smoothing rings being adapted to improve the homogeneity of the gas flow.

2. Apparatus for separating particles from a gas constructed and arranged for use and operation substantially as herein described and with reference to the accompanying drawing.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (2)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Apparatus for removing particles from a gas stream This invention relates to apparatus for removing particles from a gas stream. One well known method of removing particles from gas streams involves the use of cyclones or other forms of centrifugal separators. In general these separators cause the air to flow at a circular or helical path so that particles are centrifuged to the outside of the path where they can be corrected and the clean air may be removed from the centre of the circle or helix. It might be expected that if two such devices were operated in series then a conventional improvement would be obtained in the cleanliness of the exhaust gas. However, in tests which we have carried out we have found that a surprising number of particles some which are relatively large can continue to be entrained in gas even when it has passed through two or three stages of centrifugal separation. We believe that this problem is due to the presence in the exhaust gas from each separator of pockets of gas having relatively low energy. These pockets then pass through suceeding separator stages without sufficient deviation from their path to provide any substantial centrifugal separation. The present invention provides separation apparatus in which this problem is reached. According to the present invention apparatus for separating particles from a gas comprises at least two centrifugal separators mounted in series and flow smoothing rings mounted in gas flow between the separators, the flow smoothing rings being adapted to improve the homogeneity of a gas flow. The flow smoothing rings may for instance comprise flow straightening vanes and or a perforated gauze or other restrictor device through which the gas must flow. The invention will now be particularly described with reference to the accompanying drawing which is a schematic view of a system in accordance with the invention. In the drawing there is shown a conventional cyclone 10 having an inlet 11 into which a particle carrying gas is fed. Within the cyclone the gas is caused to flow in a helical fashion indicated at 10 with the result that at least the majority of the particles carried by the gas are centrifuged outwardly against the side of the cyclone. These particles then fall under gravity and are collected in a manifold 1 3 to be led away through a waste duct 14. The clean gas escapes from a cyclone through a central passage 1 5. It will be understood that because of the helical movement of the gas within the cyclone the exhaust gas in the pipe 1 5 will flow in a relatively turbulent fashion and will therefore include regions of relatively low energy. As explained above these regions are likely to reduce the effect of subsequent stages of centrifugal separation. Therefore in accordance with the invention a series of flow straightening vanes are provided through which the gas flows. These vanes improve the linearity of the flow which then passes through a gauze plate 1 7. The pressure drop across the plate enables any remaining irregularities in the flow to be reduced to removed altogether.The smooth gas is then allowed to flow into a second cyclone 1 8 which is identical to the cyclone 10 and therefore not described therein. It will be understood that although the flow straightening vanes 1 6 and gauze plates 1 7 are convenient devices to use it will be possible to use various other means for improving the smoothness and homogeneity of the flow. CLAIMS

1. Apparatus for separating particles from a gas comprising at least two centrifugal separators mounted in series and flow separating rings mounted in a gas flow between the separators, the flow smoothing rings being adapted to improve the homogeneity of the gas flow.

2. Apparatus for separating particles from a gas constructed and arranged for use and operation substantially as herein described and with reference to the accompanying drawing.