DE9015362U1 - Centrifugal crusher - Google Patents

Description

Weber & Heim _ &igr; ^D - ⁸⁰⁰⁰ Munich

Hofbrunnstrasse

German Patent Attorneys Telephone: (089)79 9047

European Patent Attorneys Telex: 5-2128

Fax: (0 89)7 9152

P259

Centrifugal crusher

The invention relates to a centrifugal crusher for crushing material according to the preamble of claim 1.

Centrifugal crushers of the aforementioned type are known from DE 38 217 Al or from "ZEMENT-KALK-GIPS", No. 4/1989.

Centrifugal crushers of this type are used primarily for pre-crushing material, e.g. cement clinker, coal, etc., whereby process-related and throughput-related integration is provided for the entire grinding or crushing process. This makes it necessary to adjust the throughput of the centrifugal crusher to the subsequent process steps.

The centrifugal crushers known to date make use of two principles of crushing. Firstly, the cylindrical housing surrounding the rotor can have a relatively large radial distance from the outer diameter of the rotor. During operation, a material slope of crushed material therefore forms on the inner wall of the housing. This material slope is created by an initial impact crushing against the inner wall, with the accumulation of material progressing radially inwards until the downward-leading outlet cylinder of the centrifugal crusher is reached.

Another variant of crushing has so far consisted in providing stationary, vertical impact plates made of hardened material at a radial distance from the outer centrifugal edges of the rotor.

The centrally fed chunks of material that are to be shredded are accelerated by centrifugal force in the rotor and then collide in a radial direction almost vertically against these impact plates.

The crushed chunks and material particles fall from there without accumulating into the outlet funnel provided below the rotor.

The second variant of pure impact plates carries the risk of high wear. In addition, it was also found that the wear on the impact plates could vary greatly depending on the material throughput of the goods to be shredded.

These disadvantages of the previous design and layout of centrifugal crushers have given rise to consideration of how to design centrifugal crushers more efficiently and, if possible, with less wear.

The invention is therefore based on the object of improving centrifugal crushers of this type in such a way that more effective crushing work is achieved, if possible with improved wear behavior of parts.

This object is achieved according to the invention in a centrifugal crusher of the generic type by the features of claim 1.

A basic idea of the invention is therefore to reduce the crushing space for the material to be crushed, which is also referred to as the radial clearance between the centrifugal edges or the outer circumference of the rotor and the circular

ring-shaped impact plates, can be designed to be adjustable in the radial direction. This is suitably achieved by the adjustability and displacement of the impact plates in the radial direction, whereby a lamellar overlap in the edge area or a displacement along wedge- or cone-shaped intermediate pieces is conceivable.

The core idea behind this design measure is that for a certain material throughput, i.e. t/h of material to be shredded, there is an optimal distance between the outer circumference of the rotor and the inner surface of the impact plates. This optimal distance appears to be due to the fact that at full load, i.e. at maximum material throughput, the chunks of material leaving the rotor at high acceleration first hit the inner surface of the impact plates, where they are shredded and burst. The shredded pieces of material bounce back from the impact plates, with these smaller pieces of material and particles reflected back forming a particle zone Z, in which the chunks of material thrown off the rotor are already shredded or pre-shredded.

Depending on the material throughput and the rotor speed, a kind of protective particle zone is formed in front of the impact plates, in which the material chunks thrown radially outwards are already heavily crushed.

With this consideration and assuming one and the same rotation speed of the rotor, it is clear that the radial clearance of the impact plates from the outer circumference of the rotor and the material throughput are essential parameters for the optimal setting of the centrifugal crusher. If one assumes the formation of a particle zone Z in front of the impact plate at a maximum possible throughput of the

centrifugal crusher, the formation of this particle zone is no longer guaranteed if the material throughput is halved. This is because the mass of the crushed material particles reflected back by the impact plates is too small in such a case to form a particle zone in front of the impact plates in the sense of a material curtain. As a result, the coarse material or the chunks of material are actually thrown against the impact plates and only crushed there, so that this also results in relatively high wear.

The invention therefore takes the approach of adjusting the radial, clear width between the rotor and the impact plate in such a way that depending on the material throughput, the previously mentioned particle zone forms in front of the impact plates in the sense of an "impact curtain". In order to achieve this, the radial distance of the impact plates from the axis of the centrifugal crusher is designed to be variable. This can be achieved in a practical construction using wedge-shaped or conical spacers in the impact wall. The actual impact plates themselves rest against these spacers in a form-fitting manner, so to speak, and can be moved almost in a strictly radial direction. With this design, it is also possible to arrange the spacers so that they can also be moved radially, in particular outwards.

Another practical alternative is to slightly overlap or push the adjacent edge areas of impact plates to the rear when reducing the radial distance. In this form, a lamella-like impact wall would be created when the clear width is reduced, but the slight step-like transitions are not subject to any major wear during operation due to the "particle curtain".

The idea is therefore to achieve a maximum material throughput first of all a maximum clearance between

see rotor and the impact plates. If it were then necessary to reduce the material throughput, the radial clearance between the rotor and the impact plates would also be reduced according to empirical curves. This would happen to such an extent that, even with a smaller material throughput, a sufficiently dense particle zone would be created in front of the impact plates in which the coarse material would already be largely crushed or pre-crushed.

This measure of radial displacement of the impact plates therefore reduces wear on the impact plates on the one hand. On the other hand, a significantly better efficiency is achieved for the material crushing even with high solids concentrations, since the impact plates are operated at a fictitious "full load" so to speak. In addition, operating the centrifugal crusher with an optimally adjusted particle zone in front of the impact wall also improves the fines content of the centrifugal crusher. It can be expected that the fines content will be increased from, for example, 50% to 75%. This brings energy advantages, since in the subsequent crushing process, less energy is required overall to crush the material to the desired particle size.

The invention is explained in more detail below using schematic drawings. They show:

Fig. 1 is a vertical section through a centrifugal crusher, with the left half schematically showing the use of a "material slope" as a crushing wall and the right half showing the use of "impact plates";

Fig. 2 is a partial view of the upper right part of the centrifugal crusher according to Fig. 1 in the area of the impact plates;

Fig. 3 is a schematic plan view of a variant of the impact plate arrangement with a radial reduction of the distance from the axis of the centrifugal crusher and

Fig. 4 shows another variant for the movement of the impact plates.

The centrifugal crusher 1 shown in Fig. 1 with a vertical section schematically shows the two previously known options for the design and operation of centrifugal crushers.

In principle, the centrifugal crusher 1 has a central drive shaft 18, to which a rotor 5 is rigidly connected in the upper area. This rotor 5 receives the material 14 to be crushed via a central material feed hopper 3. From there, the material chunks are hurled into the actual crushing chamber 12 by the rotation of the rotor 5 via channel-like acceleration zones 23 and the radially outwardly arranged centrifugal edges 6.

While in the right part of Fig. 1 the crushing chamber 12 is limited radially outward by impact plates 10, in the left part a material slope 7 is shown, against and into which the material chunks are thrown by the rotor.

The rotor 5 and the impact plates 10 are surrounded at a distance by a cylindrical housing 2, which is provided with a bevelled housing cover 4 at the top. At the bottom, the centrifugal crusher 1 has a circular cylindrical outlet 17 for the material 15 to be crushed. The diameter

The diameter of this outlet 17 is approximately in the area of the beginning of the material slope 7 or a "particle zone" Z, as will be described below. The material to be shredded is fed downwards to the further shredding process via an outlet funnel 16. An electric motor 19 is connected to the housing of the centrifugal crusher 1 and applies the rotational speed to the shaft 18 or the rotor 5 via a belt drive 21.

In order to make the mode of operation of the centrifugal crusher 1 clearer with regard to the radial adjustability of the impact plates, the upper right part of the centrifugal crusher 1 according to Fig. 1 is shown in fragmentary form and slightly enlarged in Fig. 2.

The reference symbols are chosen uniformly. In Fig. 2 it is therefore clear that the material striking the impact plates 10, which are essentially circular-cylindrical with a radial distance from the sling edges 6, is reflected back in a crushed form and forms a "particle zone" Z in front of the inner wall of the impact plates. This particle zone Z extends essentially over the entire height of the impact plates 10. The following chunks of material are spun into this particle zone Z, so that the impact with the crushed material already results in crushing of this material in front of the impact plates. In the crushing chamber 12 or B, therefore, with optimal adjustment of the radial clearance between the centrifugal edges 6 and the impact plates 10, a particle curtain or a particle zone Z is formed, which protects against wear and takes over a significant part of the crushing work for the chunks of material thrown off by the rotor.

The crushed material is discharged downwards in the area of this particle zone Z. In the illustration according to Fig. 2, impact plates 10 are arranged both in the direction of a larger

Radius 'R' as well as adjustable in the direction of a smaller radius 'R'. The radial position of the impact plates 10 with respect to the centrifugal edges 6 is set empirically depending on the material throughput.

As a design option for the radial displacement of the impact plates 10, a mutual overlap 33 of the impact plates 31 in the edge area is shown in Fig. 3 in the sense of a top view of neighboring impact plates 31. The impact plates 31 shown in Fig. 3 have therefore already been moved considerably inwards towards the rotor from their maximum radial distance. The impact plates therefore slide in a slightly inclined position behind a bevel 32 on the back of the neighboring impact plate 31, so that the reduction in circumference can be compensated for in this way.

In another alternative, which is shown schematically in Fig. 4 with a top view of two adjacent impact plates 41, a wedge-like intermediate piece 42 is arranged between the impact plates 41. When the distance is reduced in the direction of the arrows R', the impact plates 41, which are beveled on the narrow sides, slide inwards along the side surfaces of the intermediate piece 42 or outwards in the opposite direction.

On the one hand, this change in the impact plates can already be set to an optimal distance by the manufacturer when the material throughput is known. However, it is also possible to design the otherwise stationary impact plates 10, 41 so that they can be moved in the radial direction using fastening rails in the base area of the housing 2.

The optimal radial adjustment of the impact plates 10 would even allow us to deviate somewhat from the high-quality, hardened materials for these impact plates, since a

A significant part of the comminution work is carried out in the upstream particle zone Z.

Claims (6)

Weber & Heim d-sooo Munich &tgr;-. ,&tgr;, .., Hofbrunnstrasse German Patent Attorneys _1Q_ Telephone: (089)79904&7 European Patent Attorneys Telex: 5-2128 Fax: (0 89)7 9152 P 259 Claims 1. Centrifugal crusher for crushing material, with an essentially central material feed, a rotor driven about a vertical axis and with a crushing chamber formed between the rotor and a radially spaced-apart impact wall made of impact plates, characterized in that the crushing chamber (12) is designed to be variable in the radial direction. 2. Centrifugal crusher according to claim 1, characterized in that the impact plates (10; 31; 41) are arranged so as to be adjustable or displaceable. 3. Centrifugal crusher according to one of claims 1 or 2, characterized in that adjacent impact plates (41) are essentially radially displaceable along a wedge- or cone-shaped intermediate piece (42). 4. Centrifugal crusher according to claim 1 or 2, characterized in that adjacent impact plates (31) are arranged in a slat-like manner so as to be displaceable and overlap in the edge region. 5. Centrifugal crusher according to one of claims 1 to 4, characterized in that the radial clear width of the crushing chamber (12) can be adjusted to form a particle zone Z in front of the impact plates (10; 31; 41) even with different material throughputs. 6. Centrifugal crusher according to one of claims 1 to 5,
characterized, that the radial clear width of the crushing chamber (12) can be changed continuously or stepwise.