Centrifugal separator comprising special separator wheel

Abstract

A centrifugal classifier including a classifier housing having at least one coarse material outlet and a classifier wheel, revolving in the classifier housing. The classifier wheel is comprised of a classifier drum and a classifier wheel shaft forming the axis of rotation of the classifier drum. A guide member is arranged near the coarse material outlet, at a set distance from the inner jacket surface of the classifier housing section surrounding the classifier drum. The guide member is configured such that classifying material flowing along the inner jacket surface at a radial distance less than or equal to the set distance circumvents the guide member and is discharged into the coarse material outlet and classifying material flowing along the inner jacket surface at a radial distance greater than the set distance is deflected in a radially inward direction toward the classifying drum.

Claims

1. A centrifugal classifier comprising: a classifier housing and a classifier wheel, which rotates in the classifier housing, the classifier wheel having a classifier drum and a classifier wheel shaft, which forms an axis of rotation of the classifier drum, the classifier drum having a plurality of classifier drum elements, an intermediate ring installed in a center of the classifier drum between two of the classifier drum elements, the intermediate ring having one or more recesses for receiving a balancing mass body, and the classifier housing having at least one coarse material outlet, wherein a guide member is arranged proximate to the at least one coarse material outlet, the guide member is arranged at a distance X from an inner jacket surface of the classifier housing section which surrounds the classifier drum, and the guide member is configured such that classifying material flowing along said inner jacket surface at a radial distance ≤X circumvents the guide member and is then discharged into the coarse material outlet, and classifying material flowing along said inner jacket surface at a radial distance >X is deflected in a radially inward direction toward the classifier drum.

2. The centrifugal classifier according to claim 1, wherein the guide member covers at least part of the coarse material outlet in a flow direction.

3. The centrifugal classifier according to claim 2, wherein the guide member covers more than 35% of the coarse material outlet in the flow direction.

4. The centrifugal classifier according to claim 3, wherein the guide member covers more than 50% of the coarse material outlet in the flow direction.

5. The centrifugal classifier according to claim 1, wherein the at least one coarse material outlet is arranged below the classifier drum, wherein air, which flows off via the classifier drum, is fed in at the coarse material outlet.

6. The centrifugal classifier according to claim 1, wherein a ratio NL/ND between a useable length of the classifier drum and a maximum usable outer diameter of the classifier drum is ≥2.

7. The centrifugal classifier according to claim 6, wherein the ratio NL/ND between the useable length of the classifier drum and the maximum useable outer diameter of the classifier drum is ≥2.3.

8. The centrifugal classifier according to claim 1, further comprising blades that project radially inwards from an inner circumferential surface of the classifier drum.

9. The centrifugal classifier according to claim 1, further comprising support rings, which are closed in a circumferential direction, project radially inwards from an inner jacket surface of the classifier drum.

10. The centrifugal classifier according to claim 1, wherein the plurality of classifier drum elements are arranged one behind the other along the axis of rotation and are connected to one another, the plurality of classifier drum elements comprising two groups of identical classifier drum elements.

11. The centrifugal classifier according to claim 10, wherein each classifier drum element forms on each of its end faces an annular disc-shaped mounting flange, the mounting flange extends relative to an inner jacket surface of the classifier drum element by an amount in a radially inward direction, whereby at least one of the mounting flanges of each classifier drum element is beveled over at least 25% of the radial extent.

12. The centrifugal classifier according to claim 1, wherein the intermediate ring has blades projecting radially inwards from an inner circumferential surface of the intermediate ring.

13. The centrifugal classifier according to claim 1, further comprising a plurality of wheel discs, each wheel disc comprising a rim connected to a hub sleeve via at least two spokes, wherein the rim forms an inner circumferential surface, which widens conically towards a fine material outlet.

14. The centrifugal classifier according to claim 13, wherein a first part and a second part of the classifier wheel shaft each form a radially outwardly projecting disc flange, which bears against an end ring surface of the hub sleeve associated with this part of the classifier wheel shaft facing the interior of the classifier drum and is screwed to the hub sleeve.

15. The centrifugal classifier according to claim 1, wherein a nominal speed of the classifier drum reaches or exceeds 160 m/s at an outer diameter of the classifier drum.

16. The centrifugal classifier according to claim 1, wherein the one or more recesses are on an outer circumferential surface of the intermediate ring and are in the form of at least one balancing groove.

17. A centrifugal classifier comprising: a classifier housing and a classifier wheel, which rotates in the classifier housing, the classifier wheel having a classifier drum and a classifier wheel shaft, which forms an axis of rotation of the classifier drum, and the classifier housing having at least one coarse material outlet, wherein a guide member is arranged proximate to the at least one coarse material outlet, the guide member is arranged at a distance X from an inner jacket surface of the classifier housing section which surrounds the classifier drum, and the guide member is configured such that classifying material flowing along said inner jacket surface at a radial distance ≤X circumvents the guide member and is then discharged into the coarse material outlet, and classifying material flowing along said inner jacket surface at a radial distance >X is deflected in a radially inward direction toward the classifier drum, wherein the guide member covers at least part of the coarse material outlet in a flow direction, wherein a degree of coverage of the coarse material outlet by the guide member is adjustable.

18. The centrifugal classifier according to claim 17, wherein the degree of coverage of the coarse material outlet by the guide member is adjusted continuously.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows a perspective view at an incline from the top and from the outside onto a centrifugal separator according to the invention.

(2) FIG. 2 shows a central longitudinal section perpendicular to the axis of rotation through the centrifugal separator according to FIG. 1.

(3) FIG. 3 shows a section along the axis of rotation through the centrifugal separator according to FIG. 1.

(4) FIG. 4 shows a front view onto the sectional surface of FIG. 3.

(5) FIG. 5 shows a frontal view onto the sectional surface of FIG. 2.

(6) FIG. 6 shows an overall view of the centrifugal separator according to the invention.

(7) FIG. 7 shows a sectional enlargement from FIG. 2 in the central area, wherein, however, the intermediate ring is optionally equipped with blades here.

(8) FIG. 8 shows a sectional enlargement from FIG. 5.

(9) FIG. 9 shows what a seal according to the invention can look like, using a section.

(10) FIG. 10 shows the same as FIG. 9, frontally from the front.

DETAILED DESCRIPTION

(11) The general operating principle of a centrifugal separator, according to which the centrifugal separator according to the invention works as well, has already been described in the introductory description. To avoid repetitions, reference is made thereto.

(12) FIG. 1 provides a first overview of a preferred exemplary embodiment of the centrifugal separator 1 according to the invention.

(13) The separator housing 2 can be seen well here. A separator wheel, which is not shown by FIG. 1, rotates in it.

(14) The separator housing 2 is preferably divided into a top part 2a and a bottom part 2b by a horizontal flange 3. The top part 2a can then preferably be released as a whole and can either be removed completely or can at least be folded open to the top by the hinges 4 and the hinge pivot axis S thereof. A simple maintenance access to the separator chamber is thus obtained, which should advantageously be cleaned regularly or, in the batch operation, after every batch.

(15) A separator wheel, which will be described in more detail shortly, rotates around the axis of rotation L in the separator chamber 10, which the separator housing 2 defines in its interior. The separator wheel can be seen well in FIG. 3, it is identified with reference numeral 7 there.

(16) As can be seen, the centrifugal separator is preferably embodied as horizontal separator. This means that the axis of rotation L, around which the separator wheel 7 revolves, runs horizontally in operational state.

(17) The loading of the roller bearings, on which the separator wheel of this centrifugal separator is mounted in order to keep the separator wheel completely or essentially free from play, is reduced through this. This is significant in the case of the high speeds, to which the roller bearings are subjected, because the separator wheel preferably rotates at an outer circumferential speed of between 50 m/s and 150 m/s. The reason for this is that the roller bearings inherently essentially bear the same load on each side of the separator wheel with horizontally running axis of rotation L. In contrast, a consistent bearing load is more difficult to realize in response to a rotation of the separator wheel around an axis, which runs vertically.

(18) Above the separator wheel, the separator housing 2 has an inlet 5 for material to be separated. The material to be separated of coarse and fine material, which is mixed with one another, is supplied to the separator chamber via this inlet 5 for material to be separated (large black arrow). As a rule, the inlet 5 for material to be separated simultaneously acts as separator inlet. At least the majority of the separation air thus also enters into the separator chamber via this inlet 5 for material to be separated. Due to the embodiment of the separator wheel according to the invention, which will be described in more detail below, which is particularly favorable from a fluidic aspect, it is possible for the first time as part of the invention to increase the product-to-air ratio. For separators according to the invention, it is ideally at least 0.5 kg, more preferably at least 0.75 kg of material to be separated per cubic meter of separation air. The optional upper limit is 1 kg of material to be separated per cubic meter of separation air. Said mixture of material to be separated and separation air preferably flows in essentially in the tangential direction. An entry oriented in this way supports the circling of the material to be separated, which creates the separating effect, in the separator chamber. As can be seen, the inlet 5 for material to be separated extends across the majority of the length of the separator chamber, viewed in the direction of the axis of rotation L.

(19) On both front ends of the separator chamber, the separator housing 2 in each case has a fine material outlet 6. Via the latter, the fine material, which is completely separated, is discharged. As a rule, the discharge takes place with the help of the separation air, which is also removed via the fine material outlet 6. As can be seen, the fine material is preferably discharged in the tangential direction, which is symbolized by the two small white arrows.

(20) The separator housing 2 has a coarse material outlet 8, which, as a rule, is arranged completely below the separator wheel 7. This coarse material outlet is symbolized by the large white arrow in FIG. 1.

(21) A certain percentage of separation air is preferably additionally blown into the separator chamber via the coarse material outlet 8 or the auxiliary air supply 9 arranged there, respectively, by means of a blower, which is not figuratively illustrated. This auxiliary air supply is symbolized by the small black arrow in FIG. 1. In particular fine material, which has unintentionally fallen into the area of the coarse material outlet or which is at risk of unintentionally falling into this area, is transported back into the separator chamber. This leads to a significant improvement of the quality of the separating result.

(22) Further details can be seen very well by means of FIG. 2, which shows a section in the vertical direction through the central area of the separator and which is to be seen in combination with FIG. 3.

(23) The cut part of the inlet 5 for material to be separated, the fine material outlet 6 located downstream therefrom in the direction of the axis of rotation L, and the coarse material outlet 8 located on the bottom, into the clear opening of which the guide member 28 protrudes, can be seen well here. It can also be seen well, how the separator housing 2 embodies a separator chamber 10 in the form of an essentially cylindrical drum, which runs horizontally here. The separator wheel 7 rotates in this drum, at a considerable distance to the inner jacket surface A of the drum. The distance A is preferably between 25% and 65% of the outer diameter of the separator wheel 7.

(24) In particularly preferred cases, it is between 32% and 40% of the outer diameter of the separator wheel 7.

(25) The separator wheel 7 according to the invention and its exact setup can best be described by means of FIGS. 6 and 7.

(26) The separator wheel 7 essentially consists of a separator drum 14 comprising a separator wheel shaft 11, which forms the axis of rotation thereof.

(27) As can be seen immediately by means of FIG. 6, the separator wheel shaft 11 is characterized in that it does not completely traverse the separator wheel 7. Instead, the interior of its separator drum 14 remains free from said separator wheel shaft, on at least 80% of its length, measured in the direction of the axis of rotation L. In this area, the separator drum 14 takes over the support function of the section of the separator wheel shaft 11 recessed here, which will be discussed in more detail shortly.

(28) As can be seen, the separator wheel shaft 11 consists of a first and a second separator wheel shaft part 12, 13. The two separator wheel shaft parts each end in a wheel disk 15. This wheel disk 15 consists of a hub sleeve 16, which is connected to a rim 18 via at least three spokes 17, preferably in one piece. In the direction of the axis of rotation L, the hub sleeve 16 has a length, which is greater than the corresponding length of the rim 18.

(29) As can be seen well, each separator wheel shaft part 12, 13 forms a disk flange 19 on its end, which faces the interior of the separator drum. This disk flange 19 bears against the inner front face of the hub sleeve 16 assigned to it. The respective disk flange 19 thus prevents that the respective separator wheel shaft part 12, 13 can be pulled out of the hub sleeve 16 to the outside. The disk flange 19 is preferably furthermore screwed to the hub sleeve 16. The bolt heads 35 of the corresponding, preferably at least six bolts, can be seen in FIG. 6 on the disk flange 19 of the first separator wheel shaft part 12.

(30) As has already been mentioned briefly above, the separator drum 14 takes over the support function in that region, in which the separator wheel shaft 11 is exposed. For this purpose, the jacket surface of the separator drum is embodied to be thick-walled. Its wall thickness can correspond essentially to the wall thickness of a hub sleeve 16. It is particularly favorable, when its wall thickness is greater than 20 mm and ideally lies in the range of between 30 mm and 48 mm, +/−0.3 mm. The separator drum is additionally reinforced by means of the ring disk-shaped support rings, which protrude to the inside and of which a plurality are provided at a distance from one another on the inner surface of the separator wheel, and which will be discussed in more detail shortly. The majority of the circumferential jacket surface of the separator drum is interrupted. It then forms a sieve- or preferably grid-like or an interrupted structure, respectively, through which suction can take place. A grid-like structure can in particular be characterized in that its apertures in the direction parallel to the longitudinal axis are longer by at least the factor 7.5 and preferably by at least the factor 10, than in the circumferential direction, which can improve the suction characteristic.

(31) Each separator wheel shaft part 12, 13 is preferably equipped as stepped shaft comprising different diameters. It is overlapped by the hub sleeve 16 preferably at the location, where said stepped shaft has its greatest diameter (except for the disk flange 19).

(32) As can be seen, the rim 18 of the wheel disk 15 is embodied as ring, which completely closed in the circumferential direction. A front face of this ring bears against a corresponding front face of the separator drum 14 and is screwed thereto. The screw connection preferably takes place from the outer side of the wheel disk 15. The receiving bores 20 for the bolt head in the rim 18 can accordingly be seen here, see FIG. 6.

(33) FIG. 6 shows, how the inner jacket surface 21 of the rim 18 widens conically towards the fine material outlet. This widening is more than only a chamfer, which is common in mechanical engineering. In the present case, it extends across the majority of the length of the rim in the direction of axis of rotation L.

(34) On its outer circumferential surface, each rim supports a type of toothing 22 or other blade-like structures, respectively. Together with the housing surrounding them, they form a type of impeller and/or mechanical deflector, which is arranged in the flow direction upstream of the sealing gap, for which it is operatively responsible, see FIG. 6 in combination with FIG. 10. It keeps particles from nonetheless reaching into this space—in spite of the air flushing of the gap between rotor and housing.

(35) On its outer circumferential surface, the rim is preferably provided with one or a plurality of sealing grooves 23, which form a part of the labyrinth-like seal, by means of which the separator wheel is sealed on its front faces with regard to the fine material outlet 6—which will be discussed in more detail later.

(36) The preferred embodiment of the spokes 17 can be understood by means of the rear part of FIG. 6. The spokes 17 preferably extend in purely radial direction from the hub sleeve 16 to the rim 18. At that location, where the spoke 17 is connected to the hub sleeve 16, each spoke 17 is exactly as long as said hub sleeve, measured in the direction of the axis of rotation L. Each spoke 17 thereby tapers towards the rim 18. This means that, as a rule, each of the spokes protrudes into the interior of the separator drum 14 and protrudes beyond the rim 18 to the outside on its opposite side in the direction of the axis of rotation L. In this way, the spokes have a relatively large surface and can thus effectively contribute to getting the separation air to rotate.

(37) The separator drum preferably consists of a plurality of separator drum elements 14a and 14b, which are manufactured separately. They are arranged one behind the other along the joint axis of rotation L and are connected to one another, preferably screw connected. Ideally, the separator drum elements have a “usable length (NL) to usable diameter (ND) ratio”, which satisfies the following equation: NL/ND=0.5 to 0.8. The useable length thereby corresponds to the total extension parallel to the axis of rotation L. A separator drum element, which extends 500 mm along the axis of rotation L, then has a diameter of 1,000 mm.

(38) It is particularly favorable, when each of the separator drum elements 14a, 14b in each case has a ring disk-shaped fastening flange 24a, 24b, 24c on both of its front faces. Said fastening flange extends in the radially inwards direction by an amount H, based on the inner jacket surface of the separator drum element, where ideally: H>30 mm, see FIG. 7, where the measure H is marked. Viewed from a different perspective, it can be said with regard to this that the free surface, which has to provide sufficient space through the clear diameter XX (see FIG. 7), as a function of the measure H, so that the flow speed falls below 30 m/sec here. It goes without saying that the construction has to nonetheless have sufficient mechanical strength.

(39) Said fastening flange thus lies completely in the interior of the separator drum. It supports the screw connection, which fixes two adjacent separator drum elements to one another. It usually also forms a centering groove or a centering protrusion 36, respectively, which is complementary thereto, via the interaction of which adjacent separator drum elements are accurately positioned relative to one another. An exact illustration of such a centering groove and of a centering protrusion, which is identified with reference numeral 36, can be found in FIG. 7, on the right, in the center.

(40) In the case of this exemplary embodiment, a pair of ring disk-shaped fastening flanges 24a, 24b, 24c, which are screwed to one another, each form one of the support rings, which has already been discussed briefly above. It is prevented by means of these support rings that the separator drum 14 expands in a barrel-shaped manner to the outside in its central area under the influence of the strong centrifugal forces causing the high operating speed, or that it is even overloaded and fails.

(41) In accordance with FIG. 6, a special intermediate ring 25 is thereby installed between two separator drum elements 14a in the center of the separator drum. This intermediate ring 25 supports one or a plurality of depressions on its outer jacket surface for receiving a balancing mass body, preferably in the form of at least one balance groove 37, see FIG. 7.

(42) This intermediate ring 25, together with the ring disk-shaped fastening flanges 24a blocked by the screw connection, furthermore realizes a wider and thus particularly highly loadable support ring of the type as already described above. This has a particularly favorable effect, because the location of the separator drum 14, which is loaded most by the centrifugal forces, is located here.

(43) The intermediate ring 25 can optionally be equipped with blades 26, which start at said intermediate ring and protrude even farther inwards in the radial direction and which serve to move the separation air without disturbing the below-described pressure compensation, see FIG. 7.

(44) In the case of earlier constructions, the separator drum had been supported in the area of today's intermediate ring 25 with a disk wheel comprising narrow apertures or swirling spokes by the separator shaft for strength reasons. In contrast, a significantly better compensation results in the case of the construction according to the invention across the maximum flow cross section thereof of the current pressure between the left half of the separator drum, which communicates with the first fine material outlet, and the right half of the separator drum, which communicates with the second fine material outlet located on the other side.

(45) The low pressure pulsations in the interior of the separator drum attained thereby improve the separating result, already because fewer agglomerations are created.

(46) As can be seen, the radially inward end of each fastening flange 24a, 24b, 24c is beveled across the entire width, for instance in the manner of a pent roof, as it is shown by FIG. 6. Due to this, two fastening flanges, which are screwed to one another, form a saddle roof-like configuration, which functionally represents a slide bevel for the material to be separated. It is reliably prevented thereby that a slightly heavier portion of the material to be separated permanently deposits at this location during operation and is held on location by means of the centrifugal forces—as could be the case as a result of a missing slide bevel in the case of a surface running parallel to the axis of rotation L.

(47) The radially inward end of the intermediate ring 25 is beveled in a saddle roof-like manner for the same reasons and, where present, the inner ends of the blades 26.

(48) It can be seen well by means of FIG. 6 that the separator drum elements as a whole consist of two groups of identical separator drum elements each. As can be seen, the two separator drum elements 14a, which meet in the center of the separator drum 14, are of identical construction and both of the separator drum elements 14b closing the separator drum 14 to the outside are also of identical construction.

(49) Finally, FIG. 6 shows that the separator drum, on its two front side ends, directly at the transition to the fine material outlet 6, has a deflector lip 27, which extends radially inwards and simultaneously at an incline in the direction of the center of the separator drum 14. Said deflector lip has the function mentioned in the introductory description.

(50) It is worth considering embodying the separator drum elements 14a and 14b as cast parts, for example of spheroidal graphite iron, which are then subsequently precision-turned. The large number of the apertures in the outer jacket surface of the separator drum 14 can be produced particularly efficiently in this way. Regardless of whether the separator drum is embodied in one or several pieces, it applies that these apertures are required for the entry of the separator air into the interior of the separator drum. In the case of the one- or multi-piece separator drum, they are also preferably the sole or at least major means for getting the separation air entering the separator chamber and the material to be separated, which is supported by it, to circulate in the separator chamber in such a way that the centrifugal forces can develop their separating effect.

(51) The guide member 28 according to the invention, which controls the access to the coarse material outlet, can be recognized and described best by means of FIGS. 2, 5 and 8.

(52) The guide member 28 according to the invention can be a blade or—in optional further interpretation of the term of the blade—a guide member, respectively, similar to a blade. The main guide surface 29 is thereof is curved in such a way that material to be separated, which hits this main guide surface 29 is deflected or thrown back, respectively, to the inside towards the separator drum 14. Fine material, which had so far possibly still been mixed to the material to be separated, which hits the blades 26, and had been entrained by it radially to the outside, thus gets the chance to nevertheless separate from the coarse material and to then be entrained by the separation air flowing off into the interior of the separator drum 14 and to be input into the interior of the separator drum 14. The classification quality is significantly improved thereby.

(53) It is important to note that said curvature is preferably a steadily concave curvature, which is inclined towards the separator drum 14. The main guide surface 29 is preferably embodied as correspondingly curved sheet metal, which is held in shape by two edge sheets 30, which border it on both sides, see FIGS. 5 and 8. The main guide surface 29 is often also additionally stabilized in its center (measured in the direction along the axis of rotation L) by means of an edge sheet 30 of the mentioned type, which is welded on here as rib-like reinforcement. The blade is preferably designed in such a way that it does not cause any swirls—at least not any significant ones.

(54) As a rule, the extension of the preferably one-piece guide member 28 according to the invention is so large in the direction parallel to the axis of rotation L that it covers the entire coarse material outlet in the direction along the axis of rotation L. Viewed in the direction of rotation, the extension of the guide member 28 according to the invention is preferably so large that the guide member covers more than 45% and preferably 60% to 70% of the clear area, with which the coarse material outlet leads into the inner jacket surface of the drum, which is embodied as part of the separator housing and which defines the separator chamber 10.

(55) It is particularly favorable when the position of the guide member can be adjusted, ideally continuously, in and opposite the direction of rotation, so that it covers more or less of the clear area, as needed, with which the coarse material outlet leads into the inner jacket surface of said drum, which is not graphically illustrated separately here. The guide member according to the invention can be set to the maximum average grain diameters of the fine material currently required by the separator in this way.

(56) The fact that the guide member 28 is attached at a distance X from the inner jacket surface of the drum, which defines the separator chamber 10, is thereby a special feature. The distance X referred to here is preferably between 3 mm and 12 mm. Ideally, it can be set, usually continuously. It applies in this context that the distance is a function of the number of coarse particles contained in the material to be separated. If many coarse particles are contained, separation must take place more quickly. There is a tendency that the distance is then set to be greater, so that a quicker expulsion results.

(57) This positioning of the guide member 28 has the result that material to be separated (coarse material), which flows along said inner jacket surface at a radial distance <X, circumvents the guide member 28 and is then discharged into the coarse material outlet by means of the centrifugal forces. Only the portion of the material to be separated, which flows along said inner jacket surface at a radial distance >X and <Y, is deflected in the direction of the separator drum 14. For the distance Y, it thereby preferably applies that (DSK-DSR)/2, whereby DSK is the inner diameter of the separator chamber and DSR the outer diameter of the separator drum. In the alternative, it can be said that the distance Y″ should lie in the range of between ½ DSR and 2/6 DSR.

(58) It is also noteworthy that the guide member 28 is particularly effective in interaction with the auxiliary air supply 9, because these two improvements together develop a synergistic effect.

(59) This can be seen quite well by means of FIG. 5.

(60) The guide member 28 forces the auxiliary air, which is blown in via the auxiliary air supply 9, to enter into the separator chamber 10 so as to be oriented in the tangential direction to a greater extent. It prevents or reduces, respectively, the tendency of the auxiliary air to hit the separation air, which rotates in the separator chamber 10 at a high speed, at an obtuse angle in an unbraked manner and to thus produce unwanted swirls.

(61) The guide member 28 simultaneously calms the air guide in the area, in which the coarse material settles, after it has circumvented the guide member 28. This is so, because the guide member 28 creates a leeward space, as compared to the separation air, which circulates in the separator chamber at a high speed, at least essentially.

(62) All of this leads to a significant improvement of the separation quality.

(63) As part of the invention, the focus is also on sealing the transition between the separator chamber 10 and the fine material outlet 6 at the front face of the separator drum 14 as effectively as possible. This is significant, because sealing errors at this location have the result that fine material, which has already been obtained with high separation quality, is contaminated with material to be separated, which has not yet been separated or not completely separated. This is to be avoided.

(64) A contact-free seal is provided here for this purpose.

(65) To be able to realize such a seal, the separator housing 2 is embodied as double-walled area in the area of the sealing location between the separator chamber 10 and the fine material outlet 6. This double-walled area is identified in FIG. 3 by reference numeral D.

(66) Compressed air is guided towards the sealing location via this double-walled area D.

(67) FIG. 10 shows the actual sealing location in enlarged illustration. Initially, a section of the rim 18 can be seen here. On its outer side, it supports a plurality of, in the present case preferably three, circumferential sealing grooves 23, as they have already been discussed briefly above, see FIG. 6 once again.

(68) On its end, close to the sealing location, the double-walled area supports a sealing insert 31, see FIG. 10 again. The sealing insert 31 is preferably embodied to be replaceable, even though the seal operates at least essentially in a contact-free manner, because, in the long run, it is in fact a wear part, in fine dust-loaded atmosphere. This sealing insert forms three raised, circumferential sealing rings 32.

(69) Each of these sealing rings 32 engages with a sealing groove 23 assigned to it on the rim 18.

(70) Due to the fact that the seal operates in a contact-free manner, the raised, circumferential sealing rings 32 and the sealing grooves 23 assigned to them form a type of labyrinth. To provide this seal with a real blocking effect, the sealing insert 31 is equipped with one or preferably a plurality of compressed air blow-in openings 34, via which compressed air is blown into the distribution channel 33 for said sealing labyrinth, which compressed air has been guided to the sealing location via the double-walled area, see FIG. 10.

(71) From the distribution channel 33, the majority of the blown-in compressed air flows off into the separator chamber 10 and keeps the path, via which it flows out, free from penetrating material to be separated. The smaller portion of the blown-in compressed air flows off into the fine material outlet 6. The latter takes place because two baffles formed of sealing rings 32 and sealing grooves 23 stand in the way of said portion of the blown-in compressed air, and not only one, which is why the flow rate is accordingly lower.

(72) Such a seal, which operates in a contact-free manner, is highly advantageous for the control of the high speeds appearing at the separator wheels according to the invention.

(73) To avoid patent law-related circumventions, the same also applies analogously for centrifugal separators, which correspond to the claims, which have already been established, with the exception that they have a single fine material outlet only on one side, in particular when it is a vertical centrifugal separator.

(74) Independent of, but also in combination with the claims, which have already been established, and/or features from the description the right is reserved to also claim protection for a centrifugal separator 1, which is characterized in that the separator wheel 7 is sealed in the area of its front faces on its outer circumference by a contact-free seal against the separator housing 2, into which blocking air is blown, which—preferably to a larger extent—flows out into the separator chamber 14 and—preferably—to a smaller extent into the fine material outlet 6.

(75) Independent of, but also in combination with the claims, which have already been established, and/or features from the description the right is reserved to also claim protection for a centrifugal separator 1, the separator drum 14 of which, on its front face ends, directly at the transition to the fine material outlet 6, has a deflector lip 27, which extends radially inwards and simultaneously at an incline in the direction of the center of the axis of rotation of the separator drum 14.

(76) Independent of, but also in combination with the claims, which have already been established, and/or features from the description the right is reserved to also claim protection for a centrifugal separator 1, in the case of which the length of a hub sleeve 16 for holding a separator wheel partial shaft 12, 13 in the direction of the axis of rotation L is greater than the length of the rim 18 of the wheel disk 15, which holds the separator drum in position.