Arrangement for a centrifugal separator
Technical field
The present invention relates to an arrangement for a centrifugal separator for separating solid and/or liquid particles suspended in gaseous media, comprising a rotor provided with sedimentation means, which is mounted rotatably in a surrounding, stationary housing and has a central inlet for the gaseous medium to be purified, the housing having on the one hand a gas outflow duct with an outlet for purified gas, which has been freed of solid and/or liquid particles on passage through the sedimentation means in the rotor, and on the other hand an outlet for the solid and or liquid particles which are deposited on the sedimentation means and then transferred onto a side wall of the housing by a centrifugal force.
Background of the invention
When gaseous media are purified of solid or liquid particles suspended in them by means of centrifugal separators of the abovementioned kind, the rotor also functions as a pump (fan) for pushing the gas onward into an outlet and in this connection moves the gas which has left the rotor in what is known as rigid body rotation, that is to say the gas rotates at a tangential speed which is almost the same as the peripheral speed of the rotor. This results in a pressure build-up p0 = 1/2p?Up , where p is the density of the gas and Up is the peripheral speed of the rotor. This peripheral speed is high and has to be slowed down and converted into an essentially axial flow in downstream outlet pipelines.
Object and solution of the invention
One object of the present invention is to provide an arrangement for a centrifugal separator of the abovementioned kind which, by means of a simple and inexpensive constructional solution, makes possible effective pressure-recovering slowing-down of the tangential flow rate of the gas and its conversion into an essentially axial flow with a relatively low flow rate and high driving pressure. To this end, the arrangement mentioned in the introduction is characterized by the features indicated in the characterizing part of patent claim 1, that is to say that, in the gas outflow duct in the
housing, downstream of the sedimentation means of the rotor, a disk is arranged, which spans the duct and has a number of gas flowthrough openings distributed in the circumferential direction which are each delimited by a tongue which projects at an angle from the downstream side of the disk and extends substantially in the circumferential direction of the disk from a rear edge of a respective hole in the disk. The disk designed in this way has been found to have an excellent capacity for converting a gas flow with a high tangential peripheral speed upstream of the disk into an axial gas flow with a relatively low tangential flow rate and high driving pressure downstream ofthe disk.
Further features and advantages ofthe invention will emerge in greater detail below with reference to the description below, the other patent claims and the accompanying drawing figures.
Brief description of the drawings
Fig. 1 is a diagrammatic side view of a centrifugal separator according to the present invention;
Fig. 2 is a perspective view of a first embodiment of a disk element according to the invention for converting a gas flow with a high tangential peripheral speed upstream of the disk into an axial gas flow with a relatively low tangential flow rate and high driving pressure downstream of the disk, and
Fig. 3 is a view similar to Fig. 2 of a slightly modified embodiment of the disk element.
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. In order to comply with increasing environmental requirements in industrial premises, it is often necessary to conduct contaminated air, or other gases, out to external purifying devices via long, bulky pipeline systems. The centrifugal separator 10 accordmg to the invention is so compact that it can be located directly on the machine which generates a contaminated gaseous
medium, and makes it possible to purify such contaminated air so effectively that it can be released into the premises directly adjacent to the associated process machine or machines.
The centrifugal separator 10 comprises a rotor 12 with a number of sedimentation means in the form of insert plates 14 mounted on it. The insert plates 14, on which solid and/or liquid particles suspended in the gas are deposited by sedimentation when the rotor rotates, can be in the form shown 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 for an intake for the gas to be purified. The connection neck 22 lies directly in front of a central inlet shaft 24 ofthe rotor 12. During operation, the gas to be purified flows into the central inlet shaft 24 in the rotor 12, after which the particles in the gas are caused to settle on the insert plates 14 when the gas flows out radially from the rapidly rotating rotor 12. The deposited particles then slide outward along the plates 14 and are finally thrown across onto the surrounding, stationary housing wall 25 by centrifugal forces.
The motor 16 is mounted in a casing 26 which is in turn suspended in the housing 20 via a radial, annular disk element 28. The housing 20 has an upper outlet 30 for purified gas and one or more outlet(s) 32 for the solid and/or liquid particles deposited on the insert plates 14 and then transferred onto the side wall 25 ofthe housing 20 by a centrifugal force.
As emerges in greater detail in Fig. 2, the annular disk element 28 is according to the invention provided with a number of gas flowthrough openings 36 distributed in the circumferential direction which are each delimited by a tongue 38 which projects backward at an angle from the downstream side of the disk element 28 and extends substantially in the circumferential direction of the disk element 28 from a rear edge 40 of a respective hole 42 in the disk. The tongues 38 and the holes 42 are curved in the circumferential direction and preferably formed by punching-out from a flat disk element made of metal. Alternatively, the disk element with its holes and tongues can be produced by injection-molding a suitable plastic material. Together, the holes 42 and the tongues 38 delimit flowthrough openings 36 which bring about pressure recovery on the downstream side of the disk element by a diffuser effect, that is to say a high tangential gas flow
rate on the upstream side of the disk element 28 is converted into a considerably lower, substantially axial gas flow rate with increased driving pressure. The tongues 38 can be made longer than the associated holes 42, as shown in Fig. 3, and extend forward toward the tongue 38 lying immediately in front so as to bring about the desired guidance of the gas flow on the downstream side of the disk element 28. In this connection, the tongues consist of separate components which are retromounted on the disk element.
If appropriate, a perforated diaphragm disk (not shown) can lie against one side of the disk element 28 and be rotatable relative to it in order for it to be possible to adjust the flowthrough area of the holes 42 in order thus to optimize the deflection ofthe gas flow at gas flows of different size.
The disk element 28 can have spokes 44 protruding radially from the housing 20, in which an outer annular element 46 is fastened, which can constitute a carrying handle by means of which the entire centrifugal separator 10 can be lifted during mounting and demounting.