EP4646293A1 - Broyeur à rouleaux - Google Patents

Broyeur à rouleaux

Info

Publication number
EP4646293A1
EP4646293A1 EP23767828.9A EP23767828A EP4646293A1 EP 4646293 A1 EP4646293 A1 EP 4646293A1 EP 23767828 A EP23767828 A EP 23767828A EP 4646293 A1 EP4646293 A1 EP 4646293A1
Authority
EP
European Patent Office
Prior art keywords
grinding
mixing bodies
mixing
roller mill
grinding bowl
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP23767828.9A
Other languages
German (de)
English (en)
Inventor
André BÄTZ
Hans Ruscheweyh
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Loesche GmbH
Original Assignee
Loesche GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Loesche GmbH filed Critical Loesche GmbH
Publication of EP4646293A1 publication Critical patent/EP4646293A1/fr
Pending legal-status Critical Current

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B02—CRUSHING, PULVERISING, OR DISINTEGRATING; PREPARATORY TREATMENT OF GRAIN FOR MILLING
    • B02C—CRUSHING, PULVERISING, OR DISINTEGRATING IN GENERAL; MILLING GRAIN
    • B02C15/00—Disintegrating by milling members in the form of rollers or balls co-operating with rings or discs
    • B02C15/001—Air flow directing means positioned on the periphery of the horizontally rotating milling surface
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B02—CRUSHING, PULVERISING, OR DISINTEGRATING; PREPARATORY TREATMENT OF GRAIN FOR MILLING
    • B02C—CRUSHING, PULVERISING, OR DISINTEGRATING IN GENERAL; MILLING GRAIN
    • B02C15/00—Disintegrating by milling members in the form of rollers or balls co-operating with rings or discs
    • B02C2015/002—Disintegrating by milling members in the form of rollers or balls co-operating with rings or discs combined with a classifier

Definitions

  • the invention relates to a roller mill with a rotating grinding bowl, the grinding bowl having a grinding bowl edge.
  • Grinding rollers or grinding bodies roll on the grinding bowl. These are preferably arranged stationary to the grinding bowl but rotatable.
  • a grinding chamber wall is also provided which surrounds the grinding bowl at least at the level of the grinding bowl edge. It can also enclose the entire roller mill.
  • a free space is formed between the grinding chamber wall and the grinding bowl edge, which is fluidically connected to a process air supply, so that when the roller mill is in operation, a process air flow flows upwards through the free space.
  • the free space can be considered not only the area between the grinding bowl edge and the grinding chamber wall, but also the area between the grinding bowl, in particular its side, and the grinding chamber wall.
  • Roller mills are used to crush various materials.
  • One of the main areas of application is the crushing of fuels such as coal or coke and the crushing of cement clinker. They are also used to process rock for ore extraction.
  • the material to be ground is placed on the grinding bowl, which rotates. The rotation causes the material to be ground, which is placed centrally on the grinding bowl, to be transported outwards towards the edge of the grinding bowl. On the way there, it is transported under the stationary grinding rollers, which rotate on their own axis, where it is crushed.
  • the at least partially crushed material to be ground is then dropped into the free space over the edge of the grinding bowl and, during operation, is transported upwards by the process air stream, which is provided to flow against gravity from below the mill.
  • a sifter is often provided in which the at least partially ground material to be ground is sifted into coarse and fine material.
  • the combination of the process air stream, which carries the particles that have fallen over the edge of the grinding bowl upwards, with these particles can also be referred to as a dust/air mixture.
  • the coarsest particles of the dust/air mixture rain down over the grinding bowl, while the finer part of the coarse fraction and the finished product are transported pneumatically to the dynamic sifter.
  • the fine material is discharged from the grinding process, whereas the coarse material is usually returned to the grinding bowl for further grinding.
  • the blade ring plays an important role in determining the required process air, product throughput and the energy efficiency of the mill. It is located below the free space and is used to direct, guide and influence the process gas flow.
  • the gas flow entering the mill interior through the blade ring should be suitable in terms of its momentum and orientation to lift and mix a large mass flow of ground material and to prevent too much material from falling in countercurrent into the annular channel which serves to supply the process air flow.
  • the invention is therefore based on the object of specifying a roller mill which can be operated efficiently.
  • the roller mill according to the invention is further developed in that mixing bodies are arranged in the free space for generating, in particular, stationary, air vortices of the process air flowing through the free space.
  • the mixing bodies have a substantially flat main body. They are arranged with an angle of inclination of at least 15° and a maximum of 60° to the flow direction of the process air flow during operation, with the mixing bodies being located with more than 90% of their body below the edge of the grinding bowl.
  • the mixing bodies are arranged and designed in the free space in such a way that at least 66% of the circumference of the mixing bodies can be freely flowed around by the process air flow during operation. In other words, this means that the mixing bodies are attached to the grinding bowl, for example, with a maximum of 34% of their circumference.
  • the invention is based on the finding that it is advantageous to deviate from the known blade ring design and geometry. As described, it has previously been assumed that it is advantageous if the process air flow flows as evenly and as directed as possible from below the grinding bowl upwards in the direction of the optionally provided classifier.
  • mixing bodies are arranged in the free space between the grinding chamber wall and the grinding bowl edge as well as in the free space below.
  • the mixing bodies are designed and arranged in such a way that they actively generate air vortices in the Generate process air flow.
  • the mixing bodies can be placed anywhere.
  • the angle of inclination is preferably between 25° and 45°, ideally around 35° to the local flow direction of the process gas.
  • the aim of the air vortex generated by the mixing bodies is to transport the ground material, which flows or falls from the edge of the grinding bowl into the free space, upwards in the direction of the outlet of the roller mill and/or the intended sifter and at the same time to separate the particles of the ground material, i.e. to disperse them.
  • the air vortex offers the advantage that the ground material that has fallen over the grinding bowl is separated into particles, enabling efficient static or dynamic sifting above the grinding bowl.
  • a further advantage is that since roller mills are also used for grinding and drying, the separation of the particles means that the warm or hot process air can reach these particles particularly well, so that efficient drying takes place.
  • the mixing bodies for generating the, in particular stationary, air vortices are inclined against the flow direction of the process air flow and are located below or mostly below the edge of the grinding bowl. This means that air vortices that arise at the edges of the mixing bodies continue and grow in the direction of flow. Since the mixing bodies are inclined downwards against the direction of flow, the largest air vortices tend to be present where the ground material runs over the edge of the grinding bowl. The air vortices thus absorb the ground material particularly well and disperse it significantly more efficiently. The air vortices also detach themselves from the mixing bodies and continue to propagate in free space.
  • the key point of the invention was that the air vortices are particularly formed at the edges of the mixing bodies. Therefore, these are preferably arranged in the The mixing bodies are arranged in such a way that at least 66% of the mixing body's circumference can be freely flowed around by the process air flow. It has been shown that, although an arrangement with only 50% or less is in principle possible, this produces significantly smaller and more unstable air vortices compared to the preferred 66% proportion.
  • the mixing bodies can be arranged anywhere in the space between the grinding bowl and the grinding chamber. However, it is preferred if the mixing bodies are arranged at an angle towards the grinding chamber wall. It has been found that this preferably creates air vortices which become larger the further they are away from the grinding chamber wall. Since the largest and most intense air vortices are desirably at the point where the material to be ground leaves the grinding bowl, namely at the edge of the grinding bowl, such an arrangement is advantageous in order to achieve the advantages according to the invention.
  • the mixing bodies can be designed and have any shape. However, it has been shown that the air vortices generated with the mixing bodies are larger and more stable if the mixing bodies are arranged and designed in such a way that the surface of the mixing bodies widens at least in sections in the flow direction of the process air flow.
  • the mixing bodies can be dimensioned and arranged in the space between the grinding bowl and the grinding chamber wall in such a way that they have a smaller cross-section at their lowest point than at a higher point. This means that they are arranged, for example, diagonally downwards in this space and widen upwards in the direction of the classifier or the grinding chamber.
  • Possible shapes of the mixing bodies are a triangular shape, an oval shape, a round shape or even a polygonal shape.
  • the mixing bodies do not all have to have the same shape, but can also have different shapes. However, it is also possible to provide only the same shape in order to simplify coordination.
  • the mixing body is designed, for example, to be triangular, pentagonal or square, with the deepest corner of the mixing body having an internal angle of between 10° and 90°, preferably around 30°. It has been shown that the formation of the vortices, which serve to transport and disperse the particles falling over the grinding bowl, is particularly pronounced at such internal angles of the corners or edges.
  • the mixing bodies can in principle be arranged anywhere in the space between the grinding bowl and the grinding chamber wall, i.e. also in the free space.
  • good results have been achieved by arranging the mixing bodies so that they extend from the grinding table edge towards the grinding chamber wall, extending downwards from the grinding table edge against the flow direction of the process air flow.
  • the mixing bodies can be arranged to extend downwards against the process air flow, viewed from the grinding table edge. In this case, their cross-section or diameter should be smaller further down than in the area of the grinding table edge.
  • the highest point of the mixing bodies in the flow direction of the process air flow is arranged essentially at the level of the dam edge.
  • Such an arrangement enables the largest and most stable air vortices to form where mixing bodies are present at the grinding table edge and the particles leave the grinding table. This in turn supports the advantageous properties of the arrangement according to the invention, such as the good dispersion and cloud-like transport of the individual particles in the direction of the classifier and/or mill outlet.
  • At least one area of the mixing bodies is located above the edge of the grinding table.
  • the edge of the grinding table is often a retaining edge, which ensures that a certain grinding bed height is present on the grinding bowl. In this case, it is in the spirit of the invention to equate the edge of the grinding table with the retaining edge. It is important here that reference is made to the edge from which the grinding material, after the partial crushing by the grinding rollers, through which centrifugal forces cause the ground material to fall or from which it is thrown off horizontally.
  • the mixing bodies can be designed to rotate with the grinding table. This means that they can be attached directly to the grinding table, for example.
  • them can be fixed in relation to the rotating grinding table.
  • they can be attached to the grinding chamber wall, the mill housing or a corresponding support structure.
  • the clear width between the point of a mixing body that is arranged closest to the grinding chamber wall and the grinding chamber wall is between 0%, preferably 5%, and 30% of the clear width between the grinding table and the grinding chamber wall at this point.
  • the mixing bodies do not extend to the grinding chamber wall. How far they can extend in the direction of the grinding chamber wall depends on the clear width between the grinding table and the grinding chamber wall. It has been shown that it is advantageous for generating the flow vortices that the process air flow in the area of the grinding chamber wall is not yet influenced by the mixing bodies. For example, with a diameter of the grinding table of approx. 6 m and the grinding chamber of approx. 8 m, a distance of approx. 0.1 m between the grinding chamber wall and the start of a mixing body is preferred.
  • the mixing bodies are arranged in such a way that a projected area of the mixing bodies, which is on a virtual plane that is perpendicular to the flow direction of the process air flow during operation of the free space, takes up between 25% and 55% of this plane.
  • the plane is arranged in such a way that it touches the lowest point of the lowest mixing body.
  • the mixing bodies arranged obliquely in the free space only take up 25% to 55% of the flow cross-section of this free space when they are projected onto a corresponding plane. This means that a large part of the free space or plane is not taken up by the mixing bodies. This is necessary to enable sufficient air flow so that the desired process air flow vortices can arise at the edges of the flow or mixing bodies.
  • the mixing bodies can be approached by the process air flow in any way.
  • a particularly good formation of the air flow vortex is achieved when a flow straightener is arranged at the same height or below the mixing bodies to generate a guided and essentially directed air flow. This means that the mixing bodies are approached by a correspondingly guided, low-turbulence flow, so that the desired vortices can be formed particularly well.
  • the mixing bodies can be designed and shaped as desired. They can be designed differently or uniformly. A uniform design of the mixing bodies offers the advantage that it is easier to optimize the air vortices.
  • the mixing bodies are arranged at a distance from each other so that the air vortices created by two adjacent mixing bodies do not influence each other.
  • Fig. 1 is a schematic view of a roller mill according to the invention with integrated classifier
  • Fig. 2 is a perspective partial view of a grinding bowl with mixing bodies
  • Fig. 3 shows a partial cross-section through a roller mill according to the invention at the level of the grinding bowl
  • Fig. 3a is a simplified sectional view along the line A-A of Fig. 3;
  • Fig. 3b is a simplified view along line B-B of Fig. 3;
  • Fig. 4 is a highly schematic drawing of a mixing body according to the invention.
  • Fig. 5 different possible shapes of mixing bodies according to the invention.
  • Fig. 1 shows a highly simplified sectional view of a roller mill 1 according to the invention.
  • This has a grinding bowl 4 which rotates as indicated. It has a grinding bowl edge 5 which in this embodiment is designed with a retaining edge 6. However, this is not absolutely necessary.
  • Stationary grinding rollers 8 are provided on the grinding bowl 4, which can rotate about their axis and can be pressed hydraulically onto the grinding bowl. In the form shown here, only two grinding rollers 8 are shown, but roller mills 1 with three, four, five or six and up to eight grinding rollers 8 are now also known.
  • the roller mill 1 is surrounded by a mill housing 12, whereby the area at the level of the grinding bowl is also referred to as the grinding chamber wall 13 of the mill housing 12.
  • the grinding chamber wall 13 also extends from below the grinding bowl 4 to the sifter ?.
  • a free space 15 is formed between the mill housing 12 and the grinding chamber wall 13.
  • the mixing bodies 20 according to the invention extend from the grinding bowl edge 5 into the free space 15 in the direction of the grinding chamber wall 13, and are explained in more detail below. In principle, however, they do not have to be provided extending away from the grinding bowl edge 15 or the retaining edge 6.
  • the basic functional principle of a roller mill 1 according to the invention is explained in detail below.
  • Below the grinding bowl 4 there is an annular channel 18. During operation, this is supplied with a process air flow 17.
  • grinding bowl 4 rotates.
  • the material to be ground is fed onto the grinding bowl 4, although the task is not made clear here.
  • the material to be ground 31 is conveyed to the edge of the grinding bowl 5. In doing so, it passes under the grinding rollers 8.
  • grinding rollers can also be understood to mean other grinding body geometries, such as balls.
  • a so-called grinding bed is formed from grinding material 31.
  • the grinding bed and the rotation of the grinding bowl 4 also cause the grinding rollers 8 to rotate.
  • the grinding material 31 is crushed by pressure and shear.
  • Partially crushed grinding material 31 and also grinding material 31 that has not yet been crushed are thrown over the grinding bowl 4 into the free space 15 by the rotation of the grinding bowl 4.
  • the height of the grinding bed can be influenced based on the height of the retaining edge 6.
  • a process air flow 17 is blown into the ring channel 18, which flows inside the roller mill 1 in the direction of the classifier 7. This carries at least a portion of the ground material 31 falling over the edge of the grinding bowl 5, which is referred to below as particles, upwards in the direction of the classifier 7.
  • the particles 32 Depending on the mass of the particles 32, they fall back onto the grinding bowl 4 just above the grinding rollers 8 or are carried to the sifter 7. A portion of the particles 32 penetrates into the sifter 7, carried by the process air flow 17. Another portion is rejected in advance and falls back onto the grinding bowl 4. In the sifter 7, a sifting takes place according to particle mass or size, with the particles 32 rejected as coarse material falling back onto the mill bowl 4.
  • mixing bodies 20 are provided in the free space 15 above the ring channel 18. These ensure that the process air 17, which is passed through the Ring channel 18 is blown into the mill 1, is swirled or air vortexes are created. This reduces the formation of strands and also allows the particles 32 carried along by the process air to be dispersed and dried particularly well. At the same time, gravity screening is also carried out.
  • the exact design of the mixing bodies 20 is essential here.
  • Fig. 2 shows a perspective view of an embodiment of mixing bodies 20 with a section of a grinding bowl 4, which is also referred to as a grinding table.
  • the mixing bodies 20 have a triangular shape, with the base of the triangle being provided on the grinding bowl edge 5. It can be firmly attached to the grinding bowl 4 or to the grinding bowl edge 5, but can also be stationary by means of another device and not rotate with the rotating grinding bowl 4.
  • Fig. 3 shows a section through the representation of Fig. 2. From this it can be seen that the mixing bodies 20, of which only one is visible, extend downwards in the direction of the annular channel 18. They are at a distance I from the grinding chamber wall 13. This is advantageous for the invention in order to form the stationary vortices according to the invention.
  • a bead armor 19 is provided on the mill housing 13, which serves to deflect the process air flow 17 towards the interior of the mill.
  • the bead armor 19 ensures that the process air flow 17 does not flow exactly vertically upwards, but is deflected towards the interior of the mill. This means that the angle of inclination a shown here does not correspond to the angle at which the mixing bodies 20 incline against the process air flow 17 or extend into it.
  • Fig. 3a a simplified schematic view is shown along the line AA in Fig. 3.
  • the mixing bodies 20 have a triangular shape with an angle ß at their tip. This angle ß is preferably around 30°.
  • Fig. 3b also shows a simple plan view along line B-B from Fig. 3, which once again shows the exact geometric arrangement of the mixing bodies 20.
  • This figure shows in particular that the mixing bodies are dimensioned such that they take up significantly less than 55% of a projection plane, which is designated E in Fig. 3.
  • E is a virtual plane that runs through the lowest tip of a mixing body 20 and is perpendicular to the flow direction 17. It is important here that the projected area of the mixing bodies 20 is dimensioned such that it takes up a maximum of 55% of this area, ideally around 35%.
  • the plane E can also only go up to the vertical on the bowl outer diameter. The 55% can therefore refer to the projection of the annular gap between the mill housing and the grinding bowl outer diameter seen from above.
  • the mixing bodies 20 can have any shape.
  • Fig. 5 shows different shapes of possible mixing bodies 20.
  • the variants of the mixing bodies a) to m) are each flat or completely flat, whereas the mixing bodies n), o) and p) have a spatial structure.
  • roller mill With the inventive design of the roller mill, it is thus possible to enable more efficient transport of particles flowing out of the grinding bowl to the sifter.

Landscapes

  • Engineering & Computer Science (AREA)
  • Food Science & Technology (AREA)
  • Crushing And Grinding (AREA)

Abstract

L'invention concerne un broyeur à rouleaux comprenant une cuve de broyage rotative ayant un bord de cuve de broyage. De plus, l'invention concerne des rouleaux de broyage. Le broyeur à rouleaux comprend également une paroi de chambre de broyage qui entoure la cuve de broyage au moins au niveau du bord de cuve de broyage. Un espace est prévu entre la paroi de chambre de broyage et le bord de cuve de broyage, ledit espace étant en communication fluidique avec une alimentation en air de traitement, de telle sorte qu'un flux d'air de traitement puisse s'écouler vers le haut à travers l'espace. Selon l'invention, ce broyeur à rouleaux est conçu de telle sorte que des éléments de mélange destinés à générer des tourbillons d'air sont situés dans l'espace, les éléments de mélange ayant un corps principal sensiblement plat et étant agencés selon un angle d'inclinaison d'au moins 15° par rapport à la direction d'écoulement du flux d'air de traitement. En outre, les éléments de mélange sont positionnés dans l'espace de telle sorte que le flux d'air de traitement puisse s'écouler librement autour d'au moins 66 % de la périphérie des éléments de mélange pendant le fonctionnement.
EP23767828.9A 2023-09-01 2023-09-01 Broyeur à rouleaux Pending EP4646293A1 (fr)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/EP2023/074025 WO2025045376A1 (fr) 2023-09-01 2023-09-01 Broyeur à rouleaux

Publications (1)

Publication Number Publication Date
EP4646293A1 true EP4646293A1 (fr) 2025-11-12

Family

ID=87974137

Family Applications (1)

Application Number Title Priority Date Filing Date
EP23767828.9A Pending EP4646293A1 (fr) 2023-09-01 2023-09-01 Broyeur à rouleaux

Country Status (3)

Country Link
EP (1) EP4646293A1 (fr)
CN (1) CN121941551A (fr)
WO (1) WO2025045376A1 (fr)

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3741611A1 (de) * 1987-12-09 1989-06-22 Babcock Werke Ag Walzenschuesselmuehle
US5090631A (en) * 1990-10-15 1992-02-25 Wark Rickey E Air flow rate control device for pulverizer vane wheel
US5386619A (en) * 1993-10-13 1995-02-07 Sure Alloy Steel Corp. Coal pulverizer and method of improving flow therein
AU674817B2 (en) * 1994-08-17 1997-01-09 Southwestern Corporation Rotating nozzle ring

Also Published As

Publication number Publication date
WO2025045376A1 (fr) 2025-03-06
CN121941551A (zh) 2026-04-28

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