WO2005123261A1

WO2005123261A1 - An arrangement in a centrifugal separator

Info

Publication number: WO2005123261A1
Application number: PCT/SE2005/000847
Authority: WO
Inventors: Torgny Lagerstedt; Claes Inge; Peter Franzén; Olev Maehans; Martin Sandgren
Original assignee: 3Nine Ab
Priority date: 2004-06-16
Filing date: 2005-06-03
Publication date: 2005-12-29
Also published as: SE0401543D0; SE527718C2; SE0401543L

Abstract

Arrangement in a centrifugal separator for separating solid and/or liquid particles suspended in gaseous media, comprising a rotor (12) provided with sedimentation means (14), which is rotatably mounted in a surrounding, stationary housing (20) and has a central inlet shaft (26) for the gaseous medium. A transverse deflection element (34) which is rotatable together with the rotor (12) is arranged upstream of the inlet shaft (26) of the rotor in the housing (20), which deflection element (34) has a surface extent in the transverse direction which covers at least a considerable part of the cross-sectional area of the inlet shaft (26) in order to preseparate larger particles in the inflowing unpurified gas toward the inside of the housing.

Description

An arrangement in a centrifugal separator

BACKGROUND OF THE INVENTION

Technical field

The present invention relates to an arrangement in a centrifugal separator for separating solid and/or liquid particles suspended in gaseous media, comprising a rotor provided with sedimentation means, which is rotatably mounted in a surrounding, stationary housing and has a central inlet shaft for the gaseous medium, an intake for the gaseous medium to be purified, located axially directly in front of the inlet shaft, being connected to the housing, the housing having on the one hand an outlet for gas which has been purified on passage through the sedimentation means in the rotor and on the other hand an outlet for separated solid and/or liquid particles.

Prior art

By way of example, SE 524 140 C2 describes an arrangement of the kind referred to in the introduction. During separation of solid and/or liquid particles suspended in gases in such separation arrangements, above all larger particles have a tendency to settle during operation of the centrifugal separator on the radially inner peripheral edges of the sedimentation means (chiefly conical insert disks) and on the inside of the rods on which the latter are mounted. Such deposits can also occur during separation of gaseous media with a relatively great liquid content. These accumulations of particles build up gradually during operation and can obstruct the fine gaps between the insert disks and thus cause problems. DE 101 35 105 Al furthermore describes a grading arrangement for solid particles where heavier particles in a container can be prevented from flowing out through an outlet for lighter particles with the aid of a non-rotating stop plate located in front of the outlet, against which the heavier particles can bounce back down into the container.

Summary of the invention

One object of the present invention is to reduce said particle accumulations on the insert disks during operation. To this end, the invention proposes an arrangement which makes possible preseparation of larger particles from the inflow of contaminated gas before this gas flow enters the central inlet shaft of the rotor. According to the invention, the arrangement referred to in the introduction is distinguished in that a transverse deflection element which is rotatable together with the rotor is arranged upstream of the inlet shaft of the rotor in the housing, which deflection element has a surface extent in the transverse direction which covers at least a considerable part of the cross- sectional area of the inlet shaft. By virtue of this, larger particles in the inflowing unpurified gas can be preseparated by impact against the rotating deflection element and then be thrown out toward the inside of the housing by the centrifugal force, while the remaining part of the unpurified gas flow flowing into the housing via the intake is first deflected radially outward and then passes around the periphery of the deflection element before it is caused to be sucked into the rotor shaft. In this way, the problem of preventing larger particles settling on the radially inner peripheral edges of the sedimentation means and on the inside of the rods on which the latter are mounted can be solved.

Preferred embodiments of the arrangement according to the invention are indicated in the dependent patent claims which follow.

The invention is described in greater detail below with reference to the accompanying drawing.

Brief description of the drawing

Fig. 1 is a diagrammatic principle sketch in side view of a first embodiment of the arrangement according to the invention;

Fig. 2 shows in a similar side view the flow paths of the gas flow through the arrangement according to the invention, certain parts of the separator being omitted, and

Fig. 3 is a diagrammatic principle sketch in side view of a second embodiment of the arrangement according to the invention.

Detailed description of preferred embodiments

In Fig. 1, reference number 10 designates a centrifugal separator according to the invention for separating solid and/or liquid particles suspended in gaseous media, for example for purifying air which contains an oil mist. The centrifugal separator 10 comprises a rotor 12 with a number of sedimentation means in the form of diagrammatically shown insert disks 14 mounted on it. The insert disks 14, on which solid and/or liquid particles suspended in the gas are temporarily deposited by sedimentation when the rotor rotates, can be in the form indicated in Fig. 1, namely conical disk elements stacked one on another, separated by a small spacing axially. The rotor 12 is driven by a motor 16 via a shaft 18. A stationary, cylindrical housing 20 surrounds the rotor 12 and has a connection neck 22 which forms an intake 24 for the gas to be purified. The connection neck 22 lies directly in front of a central inlet shaft 26 of the rotor 12. The motor 16 is mounted in a casing 28, which is in turn suspended in the housing 20. The housing 20 has an upper outlet 30 for purified gas and one or more lower outlets 32 for the solid and/or liquid particles which have been deposited on the insert disks 14 and then been transferred onto the inside of the housing 20 by a centrifugal force.

As shown in Figs 1 and 2, a disk-shaped deflection element 34 is positioned crosswise between the intake 24 and the central inlet shaft 26 of the rotor 12. The deflection element 34 is connected rotatably to the rotor 12 (in a way not illustrated further) so as to rotate together with it. This deflection element 34, which in the example shown is a round disk, can have an outside diameter which is slightly smaller than the inside diameter of the rotor shaft 26 or alternatively essentially corresponds to it. The area of the deflection element 34 should preferably be roughly 50-130%, preferably roughly 70%, of the cross-sectional area of the inlet shaft 26, depending on the size (diameter and strength) of the gas inflow.

As is shown by arrows in Fig. 2 in particular, the gas to be purified flows from the intake 24 toward the deflection element 34 during operation, the largest and heaviest particles in the gas striking the rotating deflection element 34 and being thrown out toward the inside of the surrounding housing 20 by the centrifugal force and by inertial forces when the deflection takes place and in this way being preseparated from the gas flow before it is conducted into the central shaft 26 in the rotor 12. Owing to the rotation of purified gas in the housing 20 brought about by the rotor 12, this gas forms a barrier at the broken line 36. This barrier 36 prevents the inflow, flowing virtually without rotation, from penetrating it, for which reason the gas flow can pass around the periphery of the deflection element 34 and be sucked into the shaft 26, after which small particles remaining in the gas can be made to settle on the insert disks 14 when the gas flows radially out of the rapidly rotating rotor 12. The particles which have settled slide outward along the disks 14 and are then thrown across onto the surrounding, stationary wall of the housing 20 by centrifugal forces. The particles collected on the inside of the housing 20 can then run down to and out of the lower outlet 32 in the housing.

Fig. 3 shows a second embodiment of the arrangement according to the invention, in which a conical disk 38 of smaller diameter than the conical insert disks 14 is connected to the outer periphery of the deflection element 34 to form a gap 40 for reintroducing the deflected gas flow which has been freed of heavier particles into the shaft 26 of the rotor 12. In this case as well, a barrier 36 formed by the rotating gas mass in the housing 20 prevents the inflowing gas flow from passing directly to the outside of the rotor 12 and the gas outlet 30 without first being drawn into the central shaft 26 and purified between the conical insert disks 14. However, the crosswise deflection of the inflowing gas flow before the inlet shaft of the rotor, which provides good preseparation of the heavier particle content in the gas flow and considerably smaller accumulations of particles on the insert disks, results in a reduced flow capacity through the centrifugal separator. In this respect, the embodiment according to Fig. 2 has better characteristics than that in Fig. 3.

The design of the deflection element 34 itself can be varied in many ways within the scope of the invention. In order to minimize the reduction in the flow capacity, the diameter of the deflection element 34 should be selected to be as small as possible without heavier particles in the inflow of gas being capable of passing directly into the central inlet shaft 26 of the rotor. Depending on the diameter of the inflow coming from the intake, the diameter of the deflection disk 34 can therefore be varied from being smaller than the inside diameter of the shaft to being greater than it. The rear side of the deflection disk 34 can be provided with a suitable "peak-shaped" spoiler body 42 in order to improve the aerodynamic characteristics of the deflection element, and curved, blade-like fins 44 (Fig. 2) can be present on the spoiler body 42 in order to improve the flow capacity of the separator by bringing about a pumping action on the downstream side of the deflection element 34. The front side, or upstream side, of the deflection element 34 can be slightly convex in order further to improve the aerodynamics.

Claims

Patent Claims

1. An arrangement in a centrifugal separator for separating solid and/or liquid particles suspended in gaseous media, comprising a rotor (12) provided with sedimentation means (14), which is rotatably mounted in a surrounding, stationary housing (20) and has a central inlet shaft (26) for the gaseous medium, an intake (24) for the gaseous medium to be purified, located axially directly in front of the inlet shaft (26), being connected to the housing (20), the housing having on the one hand an outlet (30) for gas which has been purified on passage through the sedimentation means (14) in the rotor (12) and on the other hand an outlet (32) for separated solid and/or liquid particles, characterized in that a transverse deflection element (34) which is rotatable together with the rotor (12) is arranged upstream of the inlet shaft (26) of the rotor in the housing (20), which deflection element (34) has a surface extent in the transverse direction which covers at least a considerable part of the cross- sectional area of the inlet shaft (26) in order to preseparate larger particles in the inflowing unpurified gas toward the inside of the housing, while the remaining part of the unpurified gas flow flowing into the housing via the intake (24) is first deflected radially outward and then passes around the peripheiy of the deflection element (34) before it is caused to flow into the rotor shaft (26).

2. The arrangement as claimed in claim 1, characterized in that the deflection element (34) has the shape of an essentially plane, circular disk.

3. The arrangement as claimed in claim 1 or 2, characterized in that the downstream side of the deflection element (34) is provided with a peak-shaped spoiler body (42).

4. The arrangement as claimed in claim 3, characterized in that curved, blade-like fins (44) are arranged on the spoiler body (42).

5. The arrangement as claimed in any one of claims 1-4, characterized in that the upstream side of the deflection element (34) is convex.

6. The arrangement as claimed in any one of claims 1-5, characterized in that the deflection element (34) has an area of roughly 50-130% of the cross- sectional area of the inlet shaft (26).

7. The arrangement as claimed in claim 6, characterized in that the deflection element (34) has an area of roughly 70% of the cross-sectional area of the inlet shaft (26).

8. The arrangement as claimed in claim 1 or 2, characterized in that an extension shield (38) inclined obliquely in the flow direction, the radial extent of which is smaller than the outside diameter of the sedimentation means (14), extends from the periphery of the deflection element.

9. The arrangement as claimed in claim 8, characterized in that the extension shield (38) has essentially the same inclination as the sedimentation means (14) and forms an obliquely inwardly backwardly inclined inlet gap (40) to the inlet shaft (26) of the rotor.