EP3925709A1 - Centrifugal separator with special separator wheel - Google Patents

Abstract

Centrifugal classifier (1) with a classifier housing (2) and a classifier wheel (7) which rotates in the classifier housing (2), the classifier wheel (7) comprising a classifier drum (14) a classifier wheel shaft (11) which forms its axis of rotation, and wherein the classifier housing (2) has at least one coarse material outlet (8), wherein a guide element (28) is arranged in the area of the at least one coarse material outlet (8), the guide element (28) being at a distance X from the inner lateral surface of the classifier drum (14 ) surrounding classifier housing section and is designed in such a way that the material to be classified, which flows along the said inner lateral surface with a radial distance ≤ X, passes under the guide element (28) and is then discharged into the coarse material outlet (8), and the material to be classified, which flows along the said inner lateral surface with flows along a radial distance >X, is deflected in a radially inward direction towards the separator drum (14).

Description

The invention relates to a centrifugal separator according to the preamble of the respective main claim.

TECHNICAL BACKGROUND

Centrifugal separators are known in various designs in the prior art.

The heart of every centrifugal separator is a separating drum rotating at high speed within a drum-shaped separating chamber.

The sifter drum is perforated, perforated or otherwise provided with a screen structure on the jacket side. Classifier air is sucked in from the fines outlet. This creates a continuous flow of classifier air. This usually enters the classifier room together with the classifiable material via the classifiable material inlet. There, the classifier air flow loaded with the classifiable material is swirled by the high-speed classifier drum to form a kind of cyclonic flow. This initially circles around the outside of the classifier drum and finally enters the interior of the classifier drum through the perforated jacket. From there, the classifier air flow flows off into the fines outlet connected to at least one end face of the classifier wheel.

In this process, the centrifugal sifter make use of the fact that the larger, more massive particles of the material to be classified are finally thrown outwards by the centrifugal forces when the material to be classified is in the cyclone-like manner The flow in the classifier room is circling. On the other hand, smaller, lower-mass particles, which are therefore only exposed to lower centrifugal forces at the same angular speed, are released from the cyclone-like flow by the inwardly flowing classifier air and sucked into the interior of the classifier drum to then be discharged together with the classifier air flow.

The market is increasingly demanding classifiers with increased throughput, with the quality of sight should also be increased or at least maintained if possible.

One possibility to increase the throughput of a generic centrifugal classifier is to increase the diameter of the classifier wheel and thus to let the classifier wheel rotate at a higher speed - since the mere increase in the classifier wheel diameter at the same nominal speed means that the recoverable fines are coarser will.

However, the increase in speed means that the systems are technically more complex, have to be balanced even more precisely and are more expensive to maintain.

THE PROBLEM UNDERLYING THE INVENTION

The invention is devoted to the problem of creating a centrifugal separator which can be balanced more easily or better and which is easier to maintain and which offers the possibility of achieving a better quality of the sifting.

THE SOLUTION ACCORDING TO THE INVENTION

According to the invention, the solution takes place by means of a centrifugal separator with the features of the first main claim.

It is a centrifugal separator with a separator housing - usually fixed relative to the foundation - and a classifier wheel that rotates in the classifier housing. The classifier housing has at least one classifying material inlet, at least one classifying air inlet, at least one coarse material outlet and at least one, mostly a first and a second fine material outlet. The sifter air, which is sucked in or fed in at least via the sifting material inlet, is usually drawn off via the latter (s). The sifter air is preferably drawn through the centrifugal sifter by means of an external fan, which sucks in on the side of the fines outlet.

The classifier wheel is formed by a classifier drum and a classifier wheel shaft carrying the classifier drum. Ideally, the classifier wheel shaft rotates around an imaginary horizontal axis. The jacket surface of the classifier drum is perforated in such a way that, during operation, it sets the classifying material hitting the classifier drum on the outside of the jacket into rotation, it being possible for further aids to generate the rotation to be present. As a rule, one can say that the classifier drum, among other things, sets the material to be classified into rotation or accelerates it further. The material to be sifted already has a certain basic translational speed when it enters the machine, with the direction changing in the course of entry. The jacket surface of the classifier drum is perforated in such a way that the classifying air flows through it in a radially inward direction.

The fine material outlets are arranged at the two front ends of the classifier drum, with a mixture of fine material and classifying air flowing out of the interior of the classifier drum into the respective fine material outlet via the respective free end face of the classifier drum. The same applies analogously if only one fine material outlet is provided.

According to the invention it is provided that the classifier wheel shaft consists of two parts that are not directly connected to one another in a load-bearing manner. The first part of the classifier wheel shaft extends outward from a first hub, which carries the classifier drum in the area of its first end face, away from the classifier drum. The second part of the classifier wheel shaft extends from a second hub, which carries the classifier drum in the area of its second end face, in the opposite direction outwards, also away from the classifier drum.

To clarify the concept, the following should first be noted:
The term "not directly connected to one another" means in the context of the invention that there is no direct flow of force from one shaft part to the other - unlike in the case of directly flanged, socketed or z. B. by means of a Hirth serration directly coupled shaft parts. The two shaft parts are accordingly arranged at a spatial distance from one another. The classifier drum is located between them. The distance between the two shaft parts is usually at least 80% of the length of the classifier drum. This is self-supporting and bridges the gap between the two shaft parts by acting as a quasi hollow shaft there.

The term "fine goods" in its broader sense does not initially have any size restrictions inherent in it. The term "fine material", however - currently optional - also has a narrower meaning and then designates such material made of ultrafine particles in which 98% of the particles have an average diameter of less than 6 µm and ideally even less than 3 µm.

The configuration according to the invention has the following consequences:
Because a shaft no longer rotates inside the classifier drum, the unbalance of which is different from the unbalance of the classifier drum, the classifier wheel can be finely balanced more easily and better. It is therefore predestined for higher speeds and is less prone to vibrations.

In addition, with the elimination of the previously centrally running classifier wheel shaft inside the classifier drum, a significantly larger clear flow cross-section is available for the mixture of classifier air and fine material. While the sifter air loaded with fine material enters the interior of the screen structure of the sifter roller at a speed of 13 to 17 m / s, the measure according to the invention slows the flow speed of the sifter air loaded with fine material directly in front of the fine material outlet to 2 to 6 m / s. This reduces the tendency of the fines to agglomerate due to turbulence in the sifter air, i.e. H. to clump.

In addition, the periodic maintenance of the classifier wheel is much easier. There is no longer a one-piece shaft, which is extremely unwieldy due to its great length - especially when it has to be manipulated in order to remove a one-piece or multi-piece classifier drum and push on the replacement part again and to position it in order to finally fix it by tightening a screw connection, which is usually difficult to access in the annular gap between the classifier drum and the classifier shaft.

In addition, the configuration according to the invention usually also improves the quality of the sifting because the clear flow cross-section within the sifter drum becomes larger. An effect that usually goes hand in hand with this is that the transport of the fine particles is improved. After passing through the sieve-like drum shell, the fine particles have more space inside the classifier drum, so less agglomeration occurs after classifying.

Another problem underlying the invention

In addition to what has been said above, the invention is also devoted to the problem of creating a centrifugal classifier which achieves a qualitatively further improved classifying result.

THE FURTHER SOLUTION IN ACCORDANCE WITH THE INVENTION

According to the invention, the solution takes place by means of a centrifugal separator with the features of the second main claim. For this, independent protection is claimed on the one hand, without reference to other claims. On the other hand, protection is also claimed for him in combination with the first main claim, making him a sub-claim.

In its broadest form, the aforementioned claim proposes a centrifugal separator as a solution, in which a one-part or multi-part guide element is arranged in the area of the at least one coarse material outlet. The guide element is arranged at a minimal distance X from the inner circumferential surface of the classifier housing section surrounding the classifier drum. It is designed in such a way that cut material, which flows along said inner jacket surface with a radial distance ≤ X, passes under the guide element and is then centrifugally discharged into the coarse material outlet. In addition, the guide element is designed in such a way that at least part of the material to be classified, which flows along the said inner jacket surface at a radial distance> X, is deflected in the radially inward direction towards the classifier drum and thereby approaches the classifier wheel, usually more than insignificantly.

To clarify the concept, the following should first be noted:
The minimum distance X is measured in the radial direction. It denotes the distance that the leading edge of the guide element, which is first reached by the incoming material to be classified when it hits the guide element, holds from the inner surface area delimiting the classifier space.

Undermining in the sense of the invention occurs when material to be classified passes the guide element on its radially outward side without receiving an impulse from the classifier wheel which changes the trajectory or changes it significantly.

The configuration according to the invention has the following consequences:
Sifted material, which flows along the said inner lateral surface with a radial distance ≤ X, is coarse material that has already separated from the fine material in the best possible way and is therefore ripe for elimination from the sifting process. It bypasses the guide element and reaches the coarse material outlet undisturbed. Since the supporting effect of the inner jacket surface does not apply here, the incoming coarse material is discharged into the coarse material outlet by the centrifugal forces acting on it. Since the coarse material reaches the coarse material outlet on the flow-calmed side, ie on the leeward side of the guide organ, there is no risk that part of the coarse material will inadvertently be carried back into the classifier room due to turbulence.

On the other hand, that part of the material to be classified which flows along the said inner circumferential surface at a radial distance> X is deflected in the direction of the classifier drum 14 and thrown back. This prevents classified material, which has already come relatively close to the clear opening that leads to the coarse material outlet, but has not yet qualitatively concluded the classification process, from the centrifugal forces and the turbulence occurring in the vicinity of the said clear opening prematurely in the Coarse material outlet is discharged. Because this would actually remove separable fine material from the sifting process, which would worsen the sifting result. Instead, the material to be sifted back towards the sifter drum is sifted again, during which the fine material that has hitherto been carried away by the coarse material is given the chance to separate from it.

OPTIONAL FURTHER DEVELOPMENT POSSIBILITIES OF THE INVENTIONS

The guide element preferably partially covers the coarse material outlet or the clear cross section which branches off to the coarse material outlet. Preferably more than 35% and better still more than 50% of said clear cross-sectional area are covered.

In this way, the guide organ gives the lee area already mentioned above an extremely effective size and it essentially prevents any premature discharge of classified material into the coarse material outlet.

Particularly preferred are constructions in which additional sifter air is fed in at the coarse material outlet, which air flows off via the sifter drum into the fine material outlet. This additional sifter air could be referred to as supporting air acting in the area of the coarse material outlet, which - in particular in conjunction with the said guide element - ensures that classified material is not discharged prematurely into the coarse material outlet. It is particularly preferred if the said classifier air is not only drawn in passively, but is actively blown in by means of a corresponding fan or from a compressed air network.

It is favorable if the ratio NL / ND between the useful length NL of the classifier drum and the maximum useful diameter ND of the classifier drum is ≥ 2 and ideally ≥ 2.3. If the optimal case is NL / ND = 2.5, then a classifier drum with a useful length of 2,000 mm has a useful diameter of 800 mm. The useful length of the classifier drum is the length over which it extends freely through the classifier space parallel to the axis of rotation L. The usable diameter is the maximum outside diameter the drum. In terms of flow technology, purely a structure that protrudes further outwards locally (e.g. flanges) are not included in the calculation of the maximum outside diameter.

By building an extremely long classifier drum, the throughput can be increased without increasing its nominal diameter. Because with increasing length, the passage area through which fine material can be sucked from the classifier space into the interior of the classifier drum increases. Since the nominal diameter of the classifier drum is not increased, the classifying result is not negatively affected. In particular, there is no increase in the entry of coarser grains into the fine material obtained, which would have to be compensated for by other measures.

At the same time, a sifter drum that is longer in the axial direction, with otherwise the same parameters (diameter, speed and air volume), tends to result in a finer sifting, since the larger flow inlet cross-section reduces the radial passage speed of the air through the sieve-like jacket of the sifter drum. Because of this, only finer particles can tend to be sucked in without overcoming the centrifugal forces acting on them.

It is particularly favorable to design the centrifugal separator in such a way that at least one, preferably both, parts of the separator wheel shaft are mounted outside the material space. The roller bearings previously arranged in the classifier room itself had to be protected at great expense from the turbulent and therefore highly invasive and abrasive atmosphere in the classifier room. Already an arrangement outside the classifier room, e.g. B. in the area of the far less turbulent flow through fine material outlet, brings an improvement here. The maximum improvement is achieved when the bearings are arranged completely outside of any atmosphere polluted by fine dust, i.e. also outside the fine material outlet, easily accessible on the side facing away from the classifier room. Here they achieve significantly longer average lifetimes, which is a decisive advantage at the high speeds.

It has proven to be particularly favorable if blades protrude radially inward from the inner circumferential surface of the sifter drum, which blades influence the movement of the sifter air, in particular guide the sifter air and increase its rotation. In this context it should be considered that the rotation of the safety air inside the classifier drum reduces the pressure that is necessary to convey the fine product towards the front outlets.

It is particularly favorable if the intermediate ring, which is to be discussed in greater detail later and is intended in particular for the center of the separator drum, has blades of the type mentioned projecting radially inward from its inner circumferential surface.

Ideally, self-contained support rings protrude radially inward from the inner circumferential surface of the classifier drum in the circumferential direction. Such support rings support the sifter drum, which is often quite long and yet comparatively thin-walled, at certain intervals, thereby preventing it from expanding like a drum at extremely high speeds and possibly even being overloaded or even failing.

It is particularly useful if the said support rings are formed in pairs from radially inwardly projecting flanges with which the sifter drum elements discussed in the next paragraph are flanged to one another.

The classifier drum preferably consists of several, preferably at least four, classifier drum elements. These are arranged one behind the other along the common axis of rotation and connected to one another, preferably screwed to one another.

It is particularly favorable if the several classifier drum elements consist of two groups of identical classifier drum elements, since the production costs can be reduced by using identical parts. Under certain circumstances, a cost-efficient modularization can even be achieved for entire series, for example by equipping larger centrifugal separators with a separator drum, which instead of two sets of two identical separator drum elements consist of two sets of two and three identical separator drum elements.

Ideally, an intermediate ring is installed in the middle of the classifier drum between two classifier drum elements. The intermediate ring has - preferably on its outer circumferential surface - one or more depressions for receiving a balancing mass body, usually in the form of at least one balancing groove.

Such an additional support ring can very effectively support the center area of the classifier drum, which is particularly stressed by the centrifugal forces, and protect it from overload.

Another possible further development of the invention consists in the fact that the classifier drum has a deflector lip at its front ends, directly at the transition to the fine material outlet. This extends obliquely radially inwards - preferably in Angle from 35 ° to 50 °. The deflector lip prevents an undesirable sifter air flow from occurring in the shortest possible way, almost in a kind of "short circuit", which flows directly from the shell into the fine material outlet on the front side of the sifter drum. This is because such an undesired sifter air flow only entrains incompletely sifted material into the fine material outlet and thus leads to a kind of partial "short circuit".

The wheel disks which connect the classifier drum to the classifier wheel shaft preferably consist of a rim which is connected to a hub shell via at least two, better still at least three, spokes.

It is particularly favorable if the rim rim forms an inner jacket surface which widens conically towards the fines outlet - not only in the sense of a bevel common in mechanical engineering, but to at least 25%, better at least 45% of the extent of the rim rim in the direction of the axis of rotation . This improves the routing of the classifier air loaded with the fine material where it exits from the end face of the classifier drum at high speed into the fine material outlet. This prevents strong turbulence due to an overly abrupt change in the clear flow cross-section or a sharp deflection when the flow velocity is too high. Excessive turbulence at this point could lead to a part of the fine material carried along by the outflowing sifter air failing prematurely and accumulating in an obstructive manner instead of being completely discharged by the outflowing sifter air.

In the context of a particularly preferred development it is provided that the length of the hub sleeve in the direction of the axis of rotation is greater than the length of the rim of the wheel disc. In this way, an anchoring of the classifier wheel shaft parts according to the invention that tends to be particularly firm and rigid, not too permanent vibrations or at least temporary imbalances (for example when passing through the subcritical speed range during start-up). Ideally, the length of the hub shell in the direction of the axis of rotation is at least 30%, better by at least 50%, greater than the corresponding length of the rim.

Another, particularly favorable option consists in that the first and the second part of the classifier wheel shaft each form a disc flange projecting radially outward. This disk flange is in each case preferably full-surface against the end ring surface of the hub sleeve assigned to this part of the classifier wheel shaft, facing the interior of the classifier drum. The disk flange is preferably screwed to the hub shell, which not least ensures additional flexural rigidity.

Further design options, further technical effects and further advantages result from the exemplary embodiment which is described below with reference to the figures.

FIGURE LIST

• the Figure 1 shows a perspective view obliquely from above and outside of a centrifugal separator according to the invention.
• the Figure 2 shows a central longitudinal section perpendicular to the axis of rotation through the centrifugal separator according to FIG Figure 1 .
• the Figure 3 shows a section along the axis of rotation through the centrifugal separator according to FIG Figure 1 .
• the Figure 4 shows a front view of the cut surface of FIG.
• the Figure 5 shows a front view of the cut surface of FIG Figure 2 .
• the Figure 6 shows an overall view of the centrifugal separator according to the invention.
• the Figure 7 shows an enlarged section from Figure 2 in the middle area, although here the intermediate ring is optionally equipped with blades.
• the Figure 8 shows an enlarged section from Figure 5 .
• the Figure 9 shows a section of what a seal according to the invention can look like.
• the Figure 10 shows the same as that Figure 9 , frontal from the front.

EXAMPLE OF EXECUTION THE FUNCTIONAL PRINCIPLE OF THE EXECUTIVE FORCE VIEWER

The basic functional principle of a centrifugal separator, according to which the centrifugal separator according to the invention also works, has already been explained in the introduction to the description. Reference is made to this to avoid repetition.

THE SECURITY HOUSING

the Figure 1 gives a first overview of a preferred embodiment of the centrifugal separator 1 according to the invention.

The classifier housing 2 is clearly visible here. One of the rotates in it Fig. 1 sifter wheel not shown.

The separator housing 2 is preferably divided by a horizon flange 3 into an upper part 2a and a lower part 2b. The upper part 2a can then preferably be released as a whole and either completely removed or at least opened up about the hinges 4 and their hinge pivot axis S. This gives you easy maintenance access to the classifier room, which should advantageously be cleaned regularly or in batch operation after each batch.

In the classifier space 10, which is delimited by the classifier housing 2 in its interior, a classifier wheel to be described in more detail below rotates about the axis of rotation L. The classifier wheel is good at Figure 3 to recognize, it is marked there with the reference number 7.

As you can see, the centrifugal classifier is preferably designed as a horizontal classifier. This means that the axis of rotation L, around which the classifier wheel 7 rotates, runs horizontally in the operational state.

This reduces the load on the roller bearings on which the classifier wheel of this centrifugal classifier is mounted in order to keep the classifier wheel completely or essentially free of play. This is important at the high speeds to which the roller bearings are exposed, since the classifier wheel preferably rotates at an outer peripheral speed of between 50 m / s and 150 m / s. The reason for this is that when the axis of rotation L runs horizontally, the roller bearings inherently carry essentially the same load on each side of the classifier wheel. In contrast, when the classifier wheel rotates about a vertically extending axis, uniform bearing loading is more difficult to achieve.

Above the sifter wheel, the sifter housing 2 has a sifting material inlet 5. The sifting material of coarse and fine material mixed with one another is fed to the sifter space via this sifting material inlet 5 (large black arrow). As a rule, the classifying material inlet 5 also functions as a classifying air inlet. Thus at least the majority of the classifier air also enters the classifier room via this classifier inlet 5. Due to the configuration of the classifier wheel according to the invention, which is to be described in more detail and which is particularly favorable in terms of flow, it is possible for the first time within the scope of the invention to increase the product-to-air ratio raise. For classifiers according to the invention, it is ideally at least 0.5 kg, even better at least 0.75 kg classed material per cubic meter of classifying air. The optional upper limit is 1 kg of material per cubic meter of air. Said mixture of classifying material and classifying air preferably flows in in a substantially tangential direction. An entry directed in this way supports the circling of the items in the sifter room, which creates the sifting effect. As can be seen, the classified material inlet 5 extends, viewed in the direction of the axis of rotation L, over the major part of the length of the classifier space.

At both ends of the classifier space, the classifier housing 2 has a fine material outlet 6 each. The finished fine material is discharged through it. The discharge usually takes place with the aid of the sifter air, which is also drawn off via the fine material outlet 6. As you can see, the fine material is preferably discharged in a tangential direction, which is symbolized by the two small white arrows.

The classifier housing 2 has a coarse material outlet 8, which as a rule is arranged completely below the classifier wheel 7. This coarse material outlet is shown in Figure 1 symbolized by the big white arrow.

Preferably, a certain proportion of sifter air is additionally blown into the sifter space via the coarse material outlet 8 or the auxiliary air supply 9 arranged there, by means of a fan (not shown in the figure). This auxiliary air supply is in Figure 1 symbolized by the small black arrow. As a result, fine material in particular that has unintentionally fallen into the area of the coarse material outlet or unintentionally into this area is produced threatens to fall, transported back to the classifier room. This leads to a significant improvement in the quality of the sighting result.

Further details are very well based on the Figure 2 can be seen, which shows a section in the vertical direction through the central area of the sifter and which in conjunction with the Figure 3 is to be considered.

The trimmed part of the material inlet 5, the fine material outlet 6 behind it in the direction of the axis of rotation L, and the coarse material outlet 8 below, into the clear opening of which the guide element 28 protrudes, can be clearly seen here. It can also be clearly seen how the separator housing 2 forms a separator space 10 in the form of an essentially cylindrical drum, which here runs horizontally. The classifier wheel 7 rotates in this drum, at a considerable distance from the inner circumferential surface A of the drum. The distance A is preferably between 25% and 65% of the outer diameter of the classifier wheel 7.

In particularly preferred cases, it is between 32% and 40% of the outer diameter of the classifier wheel 7.

THE SECURITY WHEEL

The classifier wheel 7 according to the invention and its precise structure can best be seen on the basis of FIG Figures 6 and 7th explain.

The classifier wheel 7 consists essentially of a classifier drum 14 with a classifier wheel shaft 11, which forms its axis of rotation.

How to immediately use the Fig. 6 recognizes, the classifier wheel shaft 11 is characterized in that it does not completely traverse the classifier wheel 7. Instead, the interior of his classifier drum 14 remains free of it, for at least 80% of its length, measured in the direction of the axis of rotation L. In this area, the classifier drum 14 takes on the supporting function of the section of the classifier wheel shaft 11 saved here, which will be discussed in more detail in a moment.

As you can see, the classifier wheel shaft 11 consists of a first and a second classifier wheel shaft part 12, 13. The two classifier wheel shaft parts each end in a wheel disk 15 , preferably in one piece. The hub sleeve 16 has a length in the direction of the axis of rotation L which is greater than the corresponding length of the rim rim 18.

As can be clearly seen, each classifier wheel shaft part 12, 13 forms a disk flange 19 at its end facing the interior of the classifier drum. This disk flange 19 rests against the inner end face of the hub sleeve 16 assigned to it. The respective disk flange 19 prevents the relevant classifier wheel shaft part 12, 13 from being pulled outward from the hub sleeve 16. In addition, the disk flange 19 is preferably screwed to the hub sleeve 16. The bolt heads 35 of the corresponding, preferably at least six bolts are in Figure 6 to be seen on the disk flange 19 of the first classifier wheel shaft part 12.

As already briefly mentioned above, the classifier drum 14 takes on the load-bearing function in the area in which the classifier wheel shaft 11 is exposed. For this purpose, the outer surface of the classifier drum is made thick-walled. Its wall thickness can essentially correspond to the wall thickness of a hub sleeve 16. It is particularly favorable if its wall thickness is greater than 20 mm and ideally lies in the range between 30 mm and 48 mm, +/- 0.3 mm. In addition, the classifier drum is stiffened by the inwardly protruding annular disk-shaped support rings, several of which are provided at a distance from one another on the inner surface of the classifier wheel and which will be discussed in more detail in a moment. Most of the circumferential surface of the classifier drum is perforated. It then forms a sieve-like or preferably lattice-like or a perforated structure through which suction can take place. A grid-like structure can be characterized in that its openings are longer in the direction parallel to the longitudinal axis by at least a factor of 7.5 and better by a factor of at least 10 than in the circumferential view, which can improve the suction characteristics.

Each classifier wheel shaft part 12, 13 is preferably equipped as a stepped shaft with different diameters. The hub sleeve 16 overlaps it preferably where this stepped shaft (apart from the disk flange 19) has its largest diameter.

As can be seen, the rim rim 18 of the wheel disc 15 is designed as a ring that is completely closed in itself in the circumferential direction. One end face of this ring rests against a corresponding end face of the classifier drum 14 and is screwed to it. The screw connection is preferably carried out from the outside of the Wheel disk 15. Accordingly, the receiving bores 20 for the bolt head in the rim rim 18 can be seen here, compare Figure 6 .

the Figure 6 shows how the inner circumferential surface 21 of the rim rim 18 widens conically towards the fine material outlet. This extension is more than just a common bevel in mechanical engineering. In the present case, it extends over the major part of the length of the rim in the direction of the axis of rotation L.

On its outer circumferential surface, each rim rim has a type of toothing 22 or other blade-like structures. Together with the housing surrounding them, these form a type of impeller and / or mechanical deflector, which is arranged in the flow direction in front of the sealing gap for which it is effectively responsible, cf. Fig. 6 combined with Fig. 10 . It keeps particles from getting into this space - despite the air purging of the gap between the rotor and the housing.

The rim rim is preferably provided with one or more sealing grooves 23 on its outer circumferential surface, which form part of the labyrinth-like seal with which the separator wheel is sealed on its end faces from the fine material outlet 6 - which will be discussed in more detail later.

The preferred configuration of the spokes 17 can be seen from the rear part of FIG Figure 6 comprehend. The spokes 17 preferably extend in a purely radial direction from the hub sleeve 16 to the rim rim 18. Each spoke 17 is just as long as this where it is connected to the hub sleeve 16, measured in the direction of the axis of rotation L. Each spoke 17 tapers towards the rim 18. This means that each of the spokes generally protrudes into the interior of the classifier drum 14 and protrudes outward on its opposite side in the direction of the axis of rotation L over the rim 18. In this way, the spokes have a relatively large area and can thus effectively contribute to making the sifter air rotate.

The classifier drum is preferably composed of several separately manufactured classifier drum elements 14a and 14b. These are arranged one behind the other along the common axis of rotation L and connected to one another, preferably screwed. Ideally, the classifier drum elements have a "useful length (NL) to useful diameter (ND) ratio" that satisfies the following equation: NL / ND = 0.5 to 0.8. The useful length corresponds to the total extension parallel to the axis of rotation L. A classifier drum element that extends 500 mm along the axis of rotation L then has a diameter of 1,000 mm.

It is particularly favorable if each of the sifter drum elements 14a, 14b has an annular disk-shaped fastening flange 24a, 24b, 24c on its two end faces. This extends, based on the inner circumferential surface of the classifier drum element, in the radially inward direction by an amount H. The following ideally applies: H 30 mm, cf. Fig. 7 where the dimension H is drawn. Viewed from a different perspective, it can be said that the free area, which is due to the clear diameter XX (see Fig. 7 ), depending on the dimension H, must offer enough space so that the flow velocity is below 30 m / sec falls. Nevertheless, the construction must of course have sufficient mechanical strength.

Said fastening flange is completely inside the classifier drum. It carries the screw connection that fixes two adjacent sifter drum elements to one another. It usually also forms a centering groove or a centering projection 36 complementary thereto, through the interaction of which adjacent sifter drum elements are precisely positioned relative to one another. A precise illustration of such a centering groove and a centering projection identified by the reference number 36 can be found in FIG Figure 7 right, center.

In this exemplary embodiment, a pair of annular disk-shaped fastening flanges 24a, 24b, 24c screwed to one another each form one of the support rings briefly mentioned above. These support rings prevent the classifier drum 14 from expanding outward in the shape of a barrel in its central area under the influence of the strong centrifugal forces that cause the high operating speed or from even being overloaded and failing.

As evidenced by the Figure 6 a special intermediate ring 25 is installed in the middle of the classifier drum between two classifier drum elements 14a. This intermediate ring 25 has one or more depressions on its outer lateral surface for receiving a balancing mass body, preferably in the form of at least one balancing groove 37, cf. Fig. 7 .

In addition, this intermediate ring 25 is realized together with the annular disk-shaped ones that are locked to it by the screw connection Fastening flanges 24a form a wider and therefore particularly heavy-duty support ring of the type already explained above. This has a particularly favorable effect, since the point of the classifier drum 14 that is most heavily loaded by the centrifugal forces is located here.

Optionally, the intermediate ring 25 can be equipped with blades 26 which extend further inward in the radial direction and which serve to move the sifter air without disturbing the pressure equalization explained below, see FIG. 7.

In earlier designs, for reasons of strength, the sifter drum was supported by the safety shaft in the area of today's intermediate ring 25 with a disk wheel with narrow openings or swirling spokes. In contrast, the construction according to the invention, via its maximum flow cross-section, results in a significantly better equalization of the current pressure between the left half of the classifier drum, which communicates with the first fine material outlet, and the right half of the classifier drum, which communicates with the second fine material outlet located on the other side .

The resulting lower pressure pulsations inside the classifier drum improve the classifying result, if only because fewer agglomerations occur.

As can be seen, the radially inward end of each fastening flange 24a, 24b, 24c is beveled over its entire width, roughly like a pent roof, as from Figure 6 shown. Because of this, two fastening flanges screwed together form a gable roof-like configuration, which is functionally a sliding slope represents for the sighted goods. This reliably prevents a somewhat heavier part of the items to be sifted from being permanently deposited at this point during operation and held in place by the centrifugal forces - as could be the case with a surface running parallel to the axis of rotation L due to the lack of a sliding slope.

For the same reason, the radially inward end of the intermediate ring 25 is beveled in the manner of a gable roof and, where present, the inner ends of the blades 26.

Easy to recognize from the Figure 6 is that the classifier drum elements consist of two groups of identical classifier drum elements. As can be seen, the two sifter drum elements 14a that meet in the middle of the sifter drum 14 are structurally identical and the two sifter drum elements 14b that close off the sifter drum 14 to the outside are also structurally identical.

Finally shows the Figure 6 that the classifier drum has at its two front ends, directly at the transition to the fine material outlet 6, a deflector lip 27 extending radially inward and at the same time obliquely in the direction of the center of the classifier drum 14. This has the function mentioned in the introduction to the description.

It is worth considering designing the classifier drum elements 14a and 14b as cast parts, for example made of nodular cast iron, which are then subsequently precision turned. In this way, the large number of openings in the outer jacket surface of the classifier drum 14 can be produced particularly efficiently. It does not matter whether the classifier drum is made in one or more parts, it applies that these openings are required for the entry of the classifier air into the interior of the classifier drum. They are also preferably the sole or at least predominant means of the one-part or multi-part separator wheel to make the safe air entering the separator chamber and the classified material carried by it rotate in the separator chamber in such a way that the centrifugal forces can develop their separating effect.

THE GUIDE CONTROLLING THE LARGE MATERIAL OUTLET

The guide member 28 according to the invention, which controls the access to the coarse material outlet, can best be described on the basis of FIG Figures 2 , 5 and 8th recognize and explain.

The guide element 28 according to the invention can be a shovel or - in an optionally broader interpretation of the term "shovel" - a guide element similar to a shovel. Its main guide surface 29 is curved in such a way that material to be cut which hits this main guide surface 29 is deflected or thrown back inwards towards the sifter drum 14. Fine material that may have been mixed with the material hitting the shovel 26 and was carried along by it radially outwards is given the chance to be separated from the coarse material after all and then taken with it by the classifying air flowing into the interior of the classifying drum 14 and to be entered into the interior of the classifier drum 14. This significantly improves the quality of the classification.

It should be noted that said curvature is preferably a continuously concave curvature that extends towards the classifier drum 14 tends. The main guide surface 29 is preferably designed as a correspondingly curved sheet that is held in shape at least by two edge sheets 30 that border it on both sides, cf. Fig. 5 and 8th . The main guide surface 29 is often also stabilized in its center (measured in the direction along the axis of rotation L) by an edge plate 30 of the type mentioned, which is welded on here as a rib-like reinforcement. The blade is preferably designed in such a way that it does not cause any turbulence - at least not substantially.

In the direction parallel to the axis of rotation L, the extension of the preferably one-piece guide member 28 according to the invention is generally so great that it covers the entire coarse material outlet in the direction along the axis of rotation L. Seen in the direction of rotation, the extension of the guide element 28 according to the invention is preferably so great that the guide element covers more 45% and better 60% to 70% of the clear area with which the coarse material outlet opens into the inner surface of the drum, which is designed as part of the separator housing and which the Separator space 10 limited.

It is particularly favorable if the position of the guide member is adjustable in and against the direction of rotation, ideally continuously adjustable, so that if necessary it covers more or less the clear area with which the coarse material outlet opens into the inner surface of the said drum, which is not shown here in the drawing is shown separately. In this way, the guide element according to the invention can be set to the maximum mean grain diameter of the fine material currently required by the classifier.

A special feature here is that the guide element 28 is attached at a distance X from the inner circumferential surface of the drum, which delimits the classifier space 10. The distance X meant here is preferably between 3 mm and 12 mm. Ideally, it can be adjusted, usually continuously. In this context it applies that the distance depends on the number of coarse particles contained in the material. If it contains a lot of coarse particles, it has to be separated more quickly. The distance is then set to be larger, so that ejection is faster.

This positioning of the guide element 28 means that cut material (coarse material), which flows along the said inner lateral surface with a radial distance ≤ X, undergoes the guide element 28 and is then discharged into the coarse material outlet by the centrifugal forces. Only that part of the material to be classified, which flows along said inner circumferential surface at a radial distance> X and <Y, is deflected in the direction of the classifier drum 14. For the distance Y, (DSK-DSR) / 2 preferably applies, where DSK is the inside diameter of the classifier space and DSR is the outside diameter of the classifier drum. Alternatively, it can be said that the distance Y ″ should be in the absolute range between 1/2 DSR and 2/6 DSR

It is also noteworthy that the guide element 28 is particularly effective in interaction with the auxiliary air supply 9, since these two improvements jointly develop a synergistic effect.

That can be seen quite well with the Figure 5 recognize.

The guide element 28 forces the auxiliary air blown in via the auxiliary air supply 9 to enter the separator space 10 oriented in the tangential direction. It prevents or reduces the tendency of the auxiliary air to impinge unchecked at an obtuse angle on the separator air rotating at high speed in the separator space 10 and thus to produce undesirable turbulence.

At the same time, the guide element 28 calms the air flow in the area in which the coarse material falls out after it has passed under the guide element 28. Because in this area the guide element 28 creates a leeward space, at least essentially, in relation to the classifying air circulating at high speed in the classifying space.

All of this leads to a considerable improvement in the quality of vision.

THE FRONT SEAL OF THE SECURITY WHEEL

In the context of the invention, the focus is also on sealing the transition between the classifier space 10 and the fine material outlet 6 on the end face of the classifier drum 14 as effectively as possible. This is important, because sealing defects at this point lead to the fine material already obtained with a high level of sifting quality being contaminated with sifted material that has not yet been sifted or not fully sifted. That is to be avoided.

A non-contact seal is provided for this purpose.

In order to be able to realize such a seal, the classifier housing 2 is in the area of the sealing point between the classifier space 10 and the fine material outlet 6 designed as a double-walled area. This double walled area is in Figure 3 identified by the reference symbol D.

Compressed air is supplied to the sealing point via this double-walled area D.

The actual sealing point shows the Figure 10 in an enlarged view. A section of the rim rim 18 can initially be seen here. It has several, in the present case preferably three, circumferential sealing grooves 23 on its outside, as they have already been briefly mentioned above, see again Fig. 6 .

The double-walled area has a sealing insert 31 at its end, near the sealing point, see again Fig. 10 . The sealing insert 31, although the seal works at least essentially without contact, is preferably designed to be exchangeable, since in the long term it is a wear part in an atmosphere polluted with fine dust. This sealing insert forms three raised, circumferential sealing rings 32. Each of these sealing rings 32 engages in a sealing groove 23 assigned to it on the rim rim 18.

Since the seal works without contact, the raised, circumferential sealing rings 32 and the sealing grooves 23 assigned to them form a kind of labyrinth. In order to give this seal a real blocking effect, the sealing insert 31 is equipped with one or preferably more compressed air injection openings 34 through which compressed air enters the distribution channel 33 for the said sealing labyrinth is blown in, which has been brought up to the sealing point via the double-walled area, cf. Fig. 10 .

From the distribution channel 33, the greater part of the blown compressed air flows off into the classifier space 10 and keeps the path through which it flows out of the penetrating classifiable material. The smaller part of the compressed air blown in flows into the fine material outlet 6. The latter because this part of the compressed air blown in is obstructed by two baffles formed from sealing rings 32 and sealing grooves 23, and not just one, which is why the flow rate is correspondingly lower.

Such a contactless seal is of great advantage for controlling the high speeds occurring at the classifier wheels according to the invention.

FINAL NOTES OF GENERAL NATURE

Regardless of, but also in combination with, the claims and / or features already made from the description, we reserve the right to claim protection for a centrifugal separator 1, which is characterized by the fact that the separator wheel 7 is provided with a contactless seal in the area of its end faces on its outer circumference is sealed against the classifier housing 2, into which sealing air is blown, which - preferably to a larger extent - flows out into the classifier space 14 and - preferably - to a smaller extent into the fine material outlet 6.

Regardless of, but also in combination with the claims and / or features from the description that have already been made, the right to claim protection also for a centrifugal classifier 1, the classifier drum 14 of which at its front ends, directly at the transition to the fine material outlet 6, has a radial has deflector lip 27 extending inwardly and at the same time obliquely in the direction of the center of the axis of rotation of the classifier drum 14.

Regardless of, but also in combination with the claims and / or features already made from the description, the right to claim protection also for a centrifugal separator 1, in which the length of a hub sleeve 16 for holding a separator wheel part 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 classifier drum in position.

Regardless of, but also in combination with, the claims and / or features from the description that have already been made, the right to claim protection also for a centrifugal classifier 1 with a classifier housing 2 and a classifier wheel 7 that rotates in the classifier housing 2, the classifier housing 2 has at least one classified material inlet 5, at least one coarse material outlet 8 and at least one first fine material outlet 6, the classifier wheel 7 being formed by a classifier drum 14 and a classifier wheel shaft 11 carrying the classifier drum 14, which preferably rotates about a horizontal axis, and the peripheral surface of the classifier drum 14 is perforated in such a way that, during operation, the classifying material impinging on the outer side of the classifier drum 14 is set in rotation and the classifying air flows through it in a radially inward direction, the at least one fine material outlet 6 being arranged at the end of the classifying drum 14 and via the free end face He the classifier drum 14 fine material is discharged from the interior of the classifier drum 14 into the at least one fine material outlet 6, the classifier wheel shaft 11 consists of two parts 12, 13, which are not directly connected to each other, and the first part 12 of the classifier wheel shaft 11 from a wheel disk 15 carrying the classifier drum 14 in the area of its first end face extends outward, away from the classifier drum 14, and the second part 13 of the classifier wheel shaft 11 extends outward from a wheel disk 15 supporting the classifier drum 14 in the area of its second end face, away from the Classifier drum 14 extends.

Regardless of, but also in combination with, the claims and / or features from the description that have already been made, the right to protect a centrifugal separator (1) is reserved. to claim, wherein a guide element (28) is arranged in the region of the at least one coarse material outlet (8), the guide element (28) being arranged at a distance X from the inner surface of the classifier housing section surrounding the classifier drum (14) and being designed in such a way that classifier material , which flows along said inner circumferential surface with a radial distance ≤ X, passes under the guide element (28) and is then discharged into the coarse material outlet (8), and classified material which flows along said inner circumferential surface with a radial distance> X, in a radially inward direction is deflected towards the classifier drum (14).

Regardless of, but also in combination with, the claims and / or features from the description that have already been made, the right to claim protection also for a centrifugal classifier 1 with a classifier housing 2 and a classifier wheel 7 that rotates in the classifier housing 2, the classifier housing 2 has at least one classified material inlet 5, at least one coarse material outlet 8 and at least one first fine material outlet 6, the classifier wheel 7 being formed by a classifier drum 14 and a classifier wheel shaft 11 carrying the classifier drum 14, which preferably rotates about a horizontal axis, and the peripheral surface of the classifier drum 14 is perforated in such a way that, during operation, the classifying material striking the sifter drum 14 on the outside of the casing is set in rotation and the sifting air flows through it in a radially inward direction, the at least one fine material outlet 6 being arranged at the end of the sifter drum 14 and via the free end face He the classifier drum 14 fine material is discharged from the interior of the classifier drum 14 into the at least one fine material outlet 6, the classifier wheel shaft 11 consists of two parts 12, 13 that are not directly are connected to each other in a load-bearing manner, and the first part 12 of the classifier wheel shaft 11 extends outward from a wheel disk 15 supporting the classifier drum 14 in the area of its first end face, away from the classifier drum 14, and the second part 13 of the classifier wheel shaft 11 extends from a classifier drum 14 extends outward, away from the classifier drum 14, in the region of its second end face, a guide element (28) being arranged in the region of the at least one coarse material outlet (8), the guide element (28) at a distance X from the inner circumferential surface of the classifier housing section surrounding the classifier drum (14) is arranged and designed so that classifiable material, which flows along the said inner jacket surface with a radial distance ≤ X, passes under the guide element (28) and is then discharged into the coarse material outlet (8), and classifiable material, which flows along said inner circumferential surface at a radial distance> X, in a radially inward direction is deflected towards the classifier drum (14).

Regardless of, but also in combination with, the claims and / or features from the description that have already been made, the right to claim protection for a centrifugal separator as well, with at least one, preferably both parts (12, 13) of the separator wheel shaft (11) outside the separator space (10) are stored, the two parts of the classifier wheel shaft (12, 13) preferably also reaching through the respective fine material outlet (6) and only outside of the fine material outlet (6), on the side of which is remote from the classifier space (10).

To avoid circumventing patent law, the same applies analogously to centrifugal separators that meet the claims already made, with the exception that they only have a single fine material outlet on one side, especially when it comes to vertical centrifugal separators.

REFERENCE LIST

1

Centrifugal separator

2

Classifier housing

2a

Upper part of the classifier housing

2 B

Lower part of the classifier housing

3

Horizontal flange

4th

Hinge for swiveling open the separator housing, which has previously been detached in two halves

5

Sight entry

6th

Fine material outlet

7th

Classifier wheel

8th

Coarse material outlet

9

Auxiliary air supply

10

Classifier room

11th

Classifier wheel shaft

12th

first classifier wheel shaft part of classifier wheel shaft 11

13th

second classifier wheel shaft part of classifier wheel shaft 11

14th

Classifier drum

14a

Classifier drum element, type 1

14b

Classifier drum element, type 2

15th

Wheel disc made from hub shell, spoke and rim

16

Hub shell

17th

spoke

18th

Rim

19th

Disc flange

20th

Mounting hole for bolt head

21

Inner circumferential surface of the rim

22nd

Gearing

23

Sealing grooves

24a

washer-shaped mounting flange

24b

washer-shaped mounting flange

24c

washer-shaped mounting flange

25th

Intermediate ring

26th

shovel

27

Deflector lip

28

Governing body

29

Main guide surface

30th

Edge sheet

31

Sealing insert

32

Sealing ring

33

Distribution channel

34

Compressed air injection openings

35

Bolt heads

36

Centering protrusion

37

Balancing groove

A.

Radial distance between the inner surface of the classifier space and the outer surface of the classifier drum.

D.

double-walled area

DSK

Inner diameter of the classifier space or the drum delimiting it

DSR

Outside diameter of the classifier drum

H

Amount of extension

L.

Axis of rotation

ND

Usable diameter of the classifier drum

NL

Usable length of the classifier drum

S.

Hinge pivot axis of the hinge pair 4

X

smallest radial distance between the guide element 28 and the inner circumferential surface of the classifier space.

Y

Maximum radial distance that the classifying material circulating in the classifier space may have from the inner circumferential surface of the classifier space in order to still come into direct contact with the guide element 28

Y "

radial clearance between guide element 28 and the classifier wheel

XX

clear diameter inside an annular disk-shaped mounting flange

Claims (13)

Centrifugal classifier (1) with a classifier housing (2) and a classifier wheel (7) which revolves in the classifier housing (2), the classifier wheel (7) comprising a classifier drum (14), a classifier wheel shaft (11) which forms its axis of rotation, and wherein the sifter housing (2) has at least one coarse material outlet (8), characterized in that a guide element (28) is arranged in the region of the at least one coarse material outlet (8), wherein the guide element (28) is arranged at a distance X from the inner circumferential surface of the classifier housing section surrounding the classifier drum (14) and is designed in such a way that cut material, which flows along said inner jacket surface with a radial distance ≤ X, passes under the guide element (28) and is then discharged into the coarse material outlet (8), and material to be sifted, which flows along said inner circumferential surface at a radial distance> X, is deflected in a radially inward direction towards the sifter drum (14). Centrifugal separator (1) according to claim 1, characterized in that the guide element (28) partially covers the coarse material outlet (8) in the direction of flow and preferably more than 35%, better than 50% of the clear cross-sectional area of the coarse material outlet (8), wherein the The degree of coverage is preferably adjustable, ideally continuously. Centrifugal separator (1) according to one of the preceding claims, characterized in that the at least one coarse material outlet (8) is arranged below the classifier drum (14) and classifier air is fed in at the coarse material outlet (8) and flows off via the classifier drum (14). Centrifugal separator (1) according to one of the preceding claims, characterized in that the ratio NL / ND between the useful length (NL) of the separator drum (14) and the maximum outer useful diameter (ND) of the separator drum (14) ≥ 2 and ideally ≥ 2.3 is. Centrifugal separator (1) according to one of the preceding claims, characterized in that blades (26) protrude radially inward from the inner circumferential surface of the separating drum (14). Centrifugal separator (1) according to one of the preceding claims, characterized in that self-contained support rings protrude radially inward from the inner circumferential surface of the separating drum (14) in the circumferential direction. Centrifugal separator (1) according to one of the preceding claims, characterized in that the separator drum (14) consists of several, preferably at least four, separator drum elements (14a; 14b) which are arranged one behind the other along the common axis of rotation (L) and connected to one another, are preferably screwed to one another, the multiple classifier drum elements (14a; 14b) ideally consisting of two groups of identical classifier drum elements (14a; 14b). Centrifugal separator (1) according to Claim 7, characterized in that each separating drum element (14a; 14b) forms an annular disk-shaped fastening flange (24a; 24b; 24c) on its end faces which, based on the inner circumferential surface of the separating drum element (14a; 14b), extends around extends an amount (H) in the radially inward direction, preferably at least one fastening flange (24) of each classifier drum element (14a; 14b) being beveled over at least 25% of its radial extent. Centrifugal separator (1) according to one of claims 7 or 8, characterized in that an intermediate ring (25) is installed in the middle of the separating drum (14) between two separating drum elements (14a, 14a), the intermediate ring (25) preferably on its outer circumferential surface has one or more recesses for receiving a balancing mass body, preferably in the form of at least one balancing groove. Centrifugal separator (1) according to one of Claims 7 to 9 in conjunction with Claim 4, characterized in that the intermediate ring (25) has blades (26) projecting radially inward from its inner jacket surface. Centrifugal separator (1) according to one of the preceding claims, characterized in that the wheel disks (15) each consist of a rim (18) which is connected to a hub sleeve (16) via at least two, better still at least three spokes (17), wherein the rim (18) preferably forms an inner jacket surface which widens conically towards the fine material outlet (6). Centrifugal separator (1) according to claim 11, characterized in that the first and the second part of the separator wheel shaft (11) each form a radially outwardly projecting disk flange (19), which against the end ring surface facing the interior of the separator drum (14) of this part of the The hub sleeve (16) assigned to the classifier wheel shaft (11) rests and is preferably screwed to the hub sleeve (16). Centrifugal classifier according to one of the preceding claims, characterized in that the nominal speed of the classifier drum is such that the target value of 160 m / s on the outer diameter of the classifier drum is reached or exceeded.

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