High-pressure roller press with three or more rollers

Abstract

The invention relates to a high-pressure roller press with three or more rollers. According to the invention, it is provided that the rollers form a star-shaped roller gap between them.

Description

[0001] The invention relates to a high-pressure roller press with three or more rollers.

[0002] Three main methods are known for comminuting brittle material: comminution by impact, by friction, and by brittle fracture. In conventional high-pressure roller presses, the material is comminuted by applying high pressure in a roller gap, without any shearing component. The resulting regrind differs significantly in its particle shape and particle size distribution from material regrinding by other methods.

[0003] The high-pressure roller press was first described by Schönert et al. in German patent application DE 27 08 053 ​​A1. In this design, the material to be ground is drawn through a linear gap between two counter-rotating rollers. To ensure a uniform rotational speed of the rollers and to minimize slippage, precise control of the drives or a special press design is used. In this way, the comminution occurs almost exclusively through pressure, without additional mechanical stress from impact or friction.

[0004] High-pressure roller presses have proven particularly effective in cement plants for crushing raw materials or cement clinker. Nevertheless, misalignment occasionally occurs when feeding the linearly oriented roller gap. A typical high-pressure roller press consists of a stationary roller (fixed roller) and a movable roller (loose roller), which is pressed against the stationary roller by a hydraulic system. A control device ensures that the rollers neither have direct contact nor uneven alignment, thus guaranteeing constant pressure across the entire roller gap. However, it can happen that material is fed unevenly onto the elongated roller gap, causing the gap to widen at the point where more material is fed due to misalignment of the loose roller.

[0005] Another technical problem with high-pressure roller presses is the lateral displacement of the material being ground in the roller gap. Under the high pressure in the roller gap, the material attempts to move out of the way, resulting in a flow from the center of the roller gap outwards. Because the material being ground deforms plastically under these conditions and behaves like a viscous fluid, this lateral flow can impair the efficiency of the grinding process and lead to an uneven particle size distribution.

[0006] Chinese utility model CN202725237U discloses a multi-roller mill for grinding dry mineral materials. An embodiment is shown with three horizontal grinding rollers arranged in a circle, offset by 120°, and rotating towards the center to grind the material by compression. These rollers together define a circular interior. The grinding rollers have a concave surface, resulting in a central, rounded grinding zone. An additional vertical roller with a hemispherical head is inserted into this zone from above and assists the grinding process by shearing.

[0007] German patent application DE 10 2006 010 042 A1 discloses hard bodies for autogenous wear protection of roller surfaces.

[0008] Finally, US patent 4,489,895 shows a vertical mill with three millstones rotating around a common axis, which grind material on a roller plate in the manner of an edge runner mill.

[0009] The object of the invention is therefore to provide a novel grinding roller arrangement that overcomes these problems. The object underlying the invention is achieved by a high-pressure roller press with the features according to claim 1.

[0010] According to the invention, at least three grinding rollers are arranged to form a star-shaped roller gap. In the conventional design, two cylindrical grinding rollers with parallel axes and the same circumferential speed rotate side by side but in opposite directions of rotation, with the material to be ground being fed linearly onto the roller gap between the grinding rollers. However, according to the invention, three or more grinding rollers are designed as truncated double cones, the conical surfaces of which form the star-shaped roller gap. The roller gap thus extends from a common center in the directions of the arms of the star formed by the star-shaped roller gap.

[0011] In a three-roller configuration, the angle between the conical surfaces of each grinding roll is 120°; in a four-roller configuration, it is 90°. Generally, the angle between the conical surfaces of each grinding roll for n rolls can be calculated using the formula 360° / n. This design offers greater flexibility in adapting the high-pressure roller press to different materials and application requirements.

[0012] Initial tests have shown that a configuration with three grinding rollers is particularly advantageous, as it enables optimal pressure distribution and uniform grinding of the material. The grinding rollers are arranged tangentially along a circle with their axes of rotation (symmetry axes), with the star-shaped roller gap located at the center of the circle. This arrangement ensures that the material is fed and ground evenly.

[0013] A special feature of the high-pressure roller press according to the invention is that the outer surfaces of the truncated double cones of the grinding rollers form the arms of the star-shaped roller gap. The surface velocity is highest at the edges where the conical surfaces of the different grinding rollers meet. Since the surface velocity decreases at points further away from these edges due to the smaller circumference of the rollers, a velocity gradient arises within one arm of the star-shaped roller gap. This velocity gradient causes material being ground, which attempts to escape the high pressure, to be drawn back towards the center of the gap by the higher velocity. The design proposed here thus prevents the lateral displacement of the material being ground, which is frequently observed in conventional linear roller gaps.

[0014] The star-shaped structure of the star-shaped roller gap ensures that the material to be ground is drawn evenly from all directions towards the center of the gap, guaranteeing a stable material flow and uniform grinding. This configuration also allows for flexible adjustment of the number of rollers, enabling the grinding process to be optimized according to material properties and requirements.

[0015] The blunted double-conical shape of the grinding rollers also improves their self-centering. This results in a uniform pressure distribution and minimizes the risk of misalignment, which is particularly advantageous in industrial applications. The star-shaped arrangement thus improves not only the efficiency of the grinding process, but also process reliability and the particle quality of the ground material.

[0016] To extend the service life of the grinding rollers, the surface of the conical outer faces of the grinding rollers can be reinforced with hard bodies. These hard bodies hold a solid bed of crushed material that is continuously renewed and protects the grinding roller surface from abrasion.

[0017] The roller axes of the grinding rollers are arranged in such a way that single-sided drives are possible in order to avoid space problems that could occur with an arrangement with double-sided drives.

[0018] In an optional configuration, the grinding rollers could be mounted on a carousel, causing them to rotate around two perpendicular axes: one around their own axis and the other around the center of the star-shaped roller gap. The resulting Coriolis force generates a strong tilting moment on the grinding rollers, pressing them together with high force, similar to a roller mill. To accommodate these tilting movements, the roller shafts can be mounted in special pivot bearings or spherical bearings.

[0019] To ensure a uniform feed of material into the star-shaped roll gap, a funnel-shaped feeding device can be installed above the star-shaped roll gap. This device is circular in design to guide the material evenly into the arms of the star-shaped roll gap.

[0020] To ensure even more uniform distribution, the device can have an additional, inner hopper body, creating a conical annular gap between the outer wall of the feed device and the inner hopper body. This annular gap acts as an overflow, through which excess material falls and is fed back into the ground material below the grinding rollers. This recirculation system ensures that the material being ground remains in continuous circulation and that fines are efficiently separated.

[0021] The invention is explained in more detail with reference to the following figures. They show: Fig. 1 Three grinding rollers of a high-pressure roller press according to the invention in a schematic view from above onto the star-shaped roller gap, Fig. 2 the three grinding rollers from Fig. 1 in a perspective view, Fig. 3 the three grinding rollers from Fig. 2 with a feed device arranged above it, which is shown partially openwork, Fig. 4 a grinding roller from the preceding figures with a surface reinforced with hard bodies

[0022] Fig. Figure 1 shows a schematic top view of three grinding rollers 3 of a high-pressure roller press 1 according to the invention, looking down at the star-shaped roller gap 2. The grinding rollers 3 are arranged in a star shape and form the star-shaped roller gap 2 at their center. The grinding rollers 3 are designed as truncated double cones, the conical outer surfaces 5 of which form the arms of the star-shaped roller gap 2. The angle 6 between the outer surfaces 5 is 120° in this embodiment, which is typical for a configuration with three grinding rollers 3. The axes of rotation 8 of the grinding rollers 3 are arranged tangentially along a circle 7, the center of which forms the star-shaped roller gap 2. This arrangement ensures a uniform pressure distribution and enables the material to be efficiently guided into the star-shaped roller gap 2.The three grinding rollers 3 are each driven on one side by a drive M, whereby a control device not shown here ensures that the three grinding rollers 3 rotate at the same peripheral speed.

[0023] In Fig. 3 are the three grinding rollers made of Fig. Figure 1 shows a perspective view of the high-pressure roller press 1. The arrows on the three grinding rollers 3 indicate the direction of rotation. The arrow at circle 7 indicates the direction of rotation of the entire high-pressure roller press 1 when the high-pressure roller press 1 is optionally mounted on a carousel. The carousel movement of the high-pressure roller press 1, together with the rotation of the grinding rollers 3, generates a Coriolis force 14 on the grinding rollers 3, which leads to a tilting moment on the grinding rollers 3. The tilting moment compresses the three grinding rollers 3 in the three arms of the star-shaped roller gap 2. To absorb and stabilize these Coriolis forces, the axes of the grinding rollers 3 are mounted in pivot bearings 15. This mounting allows for adaptation to the tilting moment and ensures the necessary flexibility and stability of the roller movement.

[0024] In Fig. Figure 3 shows the funnel-shaped feed device 9 above the star-shaped roller gap 2, with the feed device 9 shown partially open. This device serves to guide the material being ground evenly into the arms of the roller gap 2. Inside the funnel-shaped feed device 9 is an inner funnel body 10, which, together with the outer wall of the feed device 9, forms a conical annular gap 11. This conical annular gap 11 acts as an overflow through which excess material being ground can escape in a controlled manner and be fed back in later. This design supports the continuous recirculation of the material being ground and contributes to stable and efficient comminution.

[0025] Fig.Figure 4 provides a detailed view of one of the grinding rollers 3, in particular the surfaces of the conical outer faces 5, which are reinforced with hard bodies to increase the service life of the grinding rollers 3. These hard bodies hold a solid bed of ground material between them, which is constantly renewed and protects the surface of the grinding rollers 3 from abrasion. This view also shows the circular pattern of the hard body arrangement, which supports the self-centering of the grinding rollers 3 and ensures a uniform pressure distribution along the entire roller gap 2. REFERENCE MARK LIST 1 high-pressure roller press 2 star-shaped roller gap 3 grinding rollers 5 conical lateral surfaces 6 angles between the lateral surfaces 7 tangential arrangement along a circle 8 axes of rotation 9 funnel-shaped dispensing devices 10 inner funnel body 11 conical annular gap (overflow) 12 Carousel 14 Coriolis force 16 hard bodies M drive

Claims

[1] High-pressure roller press (1) with three or more grinding rollers (3), characterized by , that the grinding rollers (3) form a star-shaped roller gap (2) between them, wherein the grinding rollers (3) each have a shape of a truncated double cone. [2] High-pressure roller press according to claim 1, characterized by , that the conical outer surfaces (5) of the respective truncated double cone of all grinding rollers (3), which are inclined to the axis of rotation (8) of the respective grinding roller (3), form the star-shaped roller gap (2). [3] High-pressure roller press according to claim 2, characterized by , that the conical shell surfaces (5) have reinforcement with hard bodies (16). [4] High-pressure roller press according to claim 2, characterized by , that the grinding rollers (3) are each driven on one side by a drive (M). [5] High-pressure roller press according to one of claims 1 to 4, characterized by, that a funnel-shaped feed device (9) for ground material is provided above the star-shaped roller gap (2). [6] High-pressure roller press according to claim 5, characterized by , that the funnel-shaped feed device (9) has in itself a further, inner funnel body (10), wherein between an outer wall of the funnel-shaped feed device (9) and the inner funnel body (10) there is a conical annular gap (11) which acts as an overflow. [7] High-pressure roller press according to any one of claims 1 to 7, characterized by , that the three or more grinding rollers (3) are arranged in a carousel (12) so that the grinding rollers (3) are each rotated by the drives (M) about their own axis of rotation and additionally about the axis of symmetry of the entire roller arrangement, which runs perpendicularly through the center of the star-shaped roller gap (2).

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