EP4294573A1

EP4294573A1 - High-pressure roller mill having vibrating lateral walls

Info

Publication number: EP4294573A1
Application number: EP22706309.6A
Authority: EP
Inventors: Niko Hachenberg
Original assignee: KHD Humboldt Wedag AG
Current assignee: KHD Humboldt Wedag AG
Priority date: 2021-02-18
Filing date: 2022-02-17
Publication date: 2023-12-27
Also published as: DE102021103889A1; KR20230145588A; CN116887922A; US20240131524A1; DE102021103889B4; WO2022175372A1

Abstract

The invention relates to a high-pressure roller mill (100) for comminuting brittle grinding stock (M), having: - at least two adjacent rotating grinding rollers (110, 120) which rotate in opposite directions and form a nip (W) therebetween, wherein a first grinding roller (110) is a fixed roller and a second grinding roller (120) is an idle roller; and - a lateral wall (150, 150') at each of the two ends of the nip (W). According to the invention, each lateral wall (150, 150') has a vibration device (160) which sets the lateral wall (150, 150') into mechanical vibration.

Description

High-pressure roller press with vibrating side walls

The invention relates to a high-pressure roller press for comminuting brittle ground material, having at least two grinding rollers arranged next to one another and rotating in opposite directions, which form a roller gap between them, with a first grinding roller being a fixed roller and a second grinding roller being a floating roller, and each a side wall at the two ends of the nip.

High-pressure roller presses are often used to crush or compact brittle, granular ground material, such as ores and rocks form a narrow nip. The ground material to be crushed or to be compacted is drawn through this nip, the ground material being crushed or compressed under the high pressure that prevails in the nip of the rollers. The result of this treatment, namely crushing or compaction, depends to a large extent on the material properties of the ground material to be crushed. The comminution in the nip described here without shearing and also without impact was first described by Schönert et al. described in the German patent application DE 27 08 053 A1 as high-pressure comminution and since then it has been regarded as a genus of comminution types in addition to grinding by shearing and breaking.

High-pressure roller presses for crushing granular material according to the Schönert method are fundamentally different from other presses that are used to crush other goods. In particular, high-pressure roller presses that are intended for crushing rock, not comparable to roller presses, for example for crushing grain. Grain is crushed in grain rollers. Grain rollers have weights in the range of a maximum of 100 kg. The entire apparatus structure of a grain roller differs greatly from that of high-pressure roller presses. Grain rollers also work with shearing. High-pressure roller presses, on the other hand, work without shearing. This means that the two grinding rollers have exactly the same surface speed in the roller gap and do not show any mutual slippage when running.

High pressure roll presses are also significantly different from strip mills for rolling steel. Steel strip rollers are characterized by their smooth running, which is required for use. The steel between the strip rolls is either very ductile because the steel to be rolled is hot worked, or the steel is cold workable. As a result, due to the nature of the rolling process, the smoothness of a steel roll is quite high. It is thus possible to operate a belt roller with two hori zontal rollers arranged one above the other, the nip pressure can be generated by the dead weight of the rollers and also by hydraulic auxiliary means. The steel to be rolled passes the nip of a strip roller in a horizontal direction, namely perpendicular to the force of gravity, which presses the upper grinding roller onto the strip steel. Depending on the steel to be rolled, strip rollers reach a nip speed of up to 200 km/h. Steel belt rolling is quite comparable to a cake dough roller that rolls over a raw pizza dough and thereby spreads the pizza dough, although the forces acting in a steel belt roller are many orders of magnitude greater. High-pressure roller presses for crushing ores and rock, on the other hand, usually have rollers arranged horizontally next to one another with egg ner passage of the ground material in the vertical direction. The roller gap speeds in high-pressure roller presses for crushing ores and rock reach speeds in the lower two-digit km/h range at most. Strip rollers for steel therefore work in a different operational extreme than high-pressure roller presses. Strip rollers run quickly and smoothly, deforming ductile steel that deforms under the roller. High-pressure roller presses run slowly, and in the nip, the brittleness of the regrind spontaneously and suddenly gives way to the pressure in the nip. In high-pressure roller presses, the rollers lie horizontally next to one another and form a nip through which the regrind runs vertically. High-pressure roller presses have a roll nip pressure of 50 MPa and more. Due to the horizontal arrangement of the rolls next to each other and the operation with brittle material, the overall mechanical behavior of the high-pressure roll press cannot be compared with the mechanical behavior of vertically stacked strip rolls, which also show a damped and even run due to the ductility of the steel to be rolled .

If the ground material in a high-pressure roller press is inhomogeneously permeated with air, the ground material has the opportunity to escape into the air space when passing through the roller gap and thus avoid the high pressure in the roller gap, which significantly reduces the shredding capacity of the high-pressure roller press. Furthermore, this can cause the high-pressure roller press to run unevenly, in that the rollers perform a rotational vibration, because the drive of the high-pressure roller press rollers is repeatedly braked and runs freely again. This abrupt change in load continues throughout the high-pressure roller press and is noticeable as vibration throughout the high-pressure roller press. Under unfavorable conditions, the vibration can continue into the foundation and, under unfavorable circumstances, even damage the foundation.

Feeding devices for regrind are known in such a high-pressure roller press, which vary the inflow of the regrind in a controlled manner, so that there is a constant heaping cone in the Forms space between the two counter-rotating rolls. Depending on the type and consistency of the material to be ground, this type of action on the roller gap is not sufficient to ensure vibration-free operation of the high-pressure roller press and to achieve continuous operation of the entire shredding machine as a high-pressure roller press. Uneven grain distribution in the ground material and air inclusions in the bed cannot always be sufficiently evened out by simply controlling the material cone in the space between the counter-rotating rollers.

The German utility model DE 202009014079 U1 proposes arranging vibration rods, such as those known from concrete casting technology as concrete vibrators, in the feed device, which reach close to the compaction zone of the ground material to be crushed. The vibrating bars deaerate the ground material by fluidizing it and thus ensure that it runs more evenly. In actual operation, it has been shown that the vibrating bars are not sufficient for the harsh conditions in the high-pressure roller press. The vibrating rods are worn out too quickly or even bent by the material to be ground. The service life of concrete vibrators or metal rods that are made to vibrate with the help of the concrete vibrator is not sufficient to ensure a sufficiently long operation without the high-pressure roller press stopping.

In order to be able to operate the surface of the rollers of high-pressure roller presses close to the maximum load and thereby maximize the grinding efficiency, it is very important that an overload of the surface of the grinding rollers in the form of an excessively high nip pressure can be safely ruled out. Otherwise, namely when operating in the overload range, surface cracks can occur on the grinding roller surface, in which case the surface finish at the broken points is lost. Due to the cracks in the surface of a grinding roller, it is no longer possible to operate the high-pressure roller press evenly. The grinding roller goes through the surface ruptures inevitably switch to percussive operation, because the nip pressure drops abruptly when the surface ruptures are passed and then suddenly rises again when the ruptured surface area leaves the nip again.

For the optimal operation of a high-pressure roller press, it is important that the pressure in the nip does not vary over time. For this purpose, the German patent application DE 102011 018705 A1 teaches how to regulate the hydraulics that maintain the pressure in the nip after the vibration of the high-pressure roll zenpress. This control leads to smooth and even running of the high-pressure roller press.

The present invention addresses the pressure distribution along the nip roll from the center of the nip to both ends of the roll nip. Because the nip is open on both sides, the material to be ground flows along the compaction zone, which begins just above the nip and extends into the nip. This flow motion results in a flow of material from the center of the nip to the two ends of the nip. Since the material to be ground can flow out of the nip at the ends of the nip, the grind follows the pressure gradient in the nip and thus avoids compression.

The above-described and undesirable pressure drop from the center of the roller gap to the two ends cannot be completely eliminated even with a uniform feeding of the roller gap by a feed device from above. As a result of this pressure drop, the pressure in the middle of the whale zenspaltes is greater. The loose roller in the high-pressure roller press thereby tends to perform a vibration movement about a vertical axis around the pressure point in the middle of the nip, the vibration frequency being 0.1 Hz or even lower. As a result, the nip is not always the same width, but rather shaped like a wedge, with the greatest nip pressure being in the center of the grinding roller. The grinding roller suffers over time Operation under a wear that transforms the cylindrical grinding roller into a waisted shape. A grinding roller deformed in this way is unusable for further use.

The object of the invention is therefore to equalize the pressure distribution along the roller gap.

The object according to the invention is achieved in that each side wall has a vibration device which causes the side wall to vibrate mechanically. Further advantageous configurations are specified in the dependent claims to claim 1.

According to the idea of the invention, it is provided that the side walls of the high-pressure roller press, which close the nip, are caused to vibrate mechanically by a vibration device. The mechanical vibrations fluidize the material to be ground and thus make it easier to pass through the nip, so that the nip pressure in the area of the ends of the nip is constantly increased. Since the nip pressure is a quotient of the contact area, namely the height of the compaction zone above the nip, and the product of the height of the actual compaction zone times the length of the nip, the nip pressure decreases in the middle of the nip and increases at the ends of the nip . As a result, the nip pressure is evened out over the length of the nip. This equalization of pressure means that the loose roller does not wobble, ie it does not oscillate in rotation by fractions of an angular degree around a vertical axis.

Without this wobbling movement, the high-pressure roller press works with constant efficiency over a longer period of time. The wear pattern of the grinding rollers is also made more even, so that the grinding rollers are not narrowed as much as a result of wear.

The energy input of the vibration device into the material to be ground is advantageously dimensioned such that the vibration device operates at a frequency between 10 Hz and 150 Hz, preferably at a frequency between 10 Hz and 60 Hz and feeds an energy input of between 0.1 kJ/m ³ and 10 kJ/m ³ , preferably between 0.1 kJ/m ³ and 1.0 kJ/m ³ into the ground material. The design required for this can be determined by simple experimental measurement. The energy input depends on the exact geometry of the side wall, which shows a wave pattern that is individual to the given geometry when it vibrates. The wave pattern, in turn, is responsible for the points at which the energy is introduced into the material to be ground. The simple experiment requires the measurement of power consumption and mass flow, which can be determined by weighing the material to be ground.

In operation it has been found that there is an optimum for the energy input. Advantageously, it can be provided that the vibration device has a control device or is connected to one which controls the vibration intensity according to the energy consumed for operation, with increased energy consumption resulting in a reduction in vibration intensity and reduced energy consumption in an increase in Vibration intensity results. This control strategy prevents the side wall from interfering too much with the grinding behavior and being damaged in the process.

The control strategy can also include control according to the energy consumption of the roller drive. It can therefore be provided that the control device regulates cumulatively or alternatively according to the energy consumption of a roller drive, with increased energy consumption of the roller drive resulting in a reduction in vibration intensity and reduced energy consumption in an increase in vibration intensity. This control strategy takes into account the fact that when a fluidization effect develops in the material to be ground, the mean pressure in the roll gap increases and requires a high drive power from the grinding rolls. However, operation with high drive power is not necessarily the most energy-efficient drive.

Finally, regulation can be carried out cumulatively or alternatively. It can be provided that the vibration device additionally after the gap width of the roller nip is regulated, with an increased gap width resulting in an increase in vibration intensity and a reduced gap width in a reduction in vibration intensity. This control strategy takes into account the observable effect that the nip spreads when the nip is overfilled. Fluidizing the regrind helps eliminate the temporary overfill effect.

Yet another cumulative or alternative control strategy can include that the vibrating device is additionally controlled according to the tendency of the floating roller to rotate about a vertical axis, with the vibration intensity increasing as the torsional vibration frequency of the floating roller increases and vice versa. This control strategy includes avoiding a wobbling movement of the floating roller by fractions of an angular degree, the wobbling occurring at a frequency of less than 0.1 Hz. This control strategy involves rather slow changes in parameters with a greater response time than is the case with the previous control strategies. Position sensors on the bearings can be used to measure the wobbling movement, which measures the relative distance between the roll axes of both axes at both ends of the rolls and stores them over a longer period of time in the range from 1 min to 10 min for a statistical analysis of the wobbling movement.

It is also possible to use the vibration device impulsively. For this purpose it can be provided that a manual triggering device is provided for the vibration device. For this purpose, an operator operates the release device when an overfill in the nip is detected.

The invention is explained in more detail with reference to the following figures. It shows:

1 shows a sketch of a high-pressure roller press according to the invention in a side view,

Fig. 2 Top view of a nip of a high-pressure roller press covered with material to be ground without side walls, here in a view of the grinding rollers, Fig. 3 Top view of a nip of a high-pressure roller press with side walls from the PRIOR ART covered with regrind,

Fig. 4 Top view of a covered with regrind nip of a high-pressure roller press according to the Invention.

FIG. 1 shows a sketch of a high-pressure roller press 100 according to the invention in a side view. The high-pressure roller press 100 according to the invention for comminuting brittle material to be ground M has at least two grinding rollers 110, 120 arranged next to one another and rotating in opposite directions. The two grinding rollers 110, 120 form between them a whale zenspalt W, through which the material to be ground M is drawn with little or no relative slippage of the grinding rollers 110, 120. A first grinding roller (110) is a fixed roller and a second grinding roller 120 is a floating roller. The floating roller 120 has two degrees of freedom of movement. This can move away from the fixed roller 110 while widening the roller gap W and also rotate about the vertical axis A by fractions of an angular degree. In order to prevent the ground material M from flowing to the opening of the nip W in the plane of the figure and falling out there, a side wall 150, 150' is provided at both openings of the nip W. According to the idea of the invention, each side wall has a vibration device which causes mechanical vibrations in each side wall 150, 150'. This mechanical vibration is transmitted into the grist M, which is near each end of the whale zenspaltes W and flows on or in the compaction zone. This vibration fluidizes the ground material M, thereby helping it to pass through the roller nip W, which is at a pressure of 50 MPa or higher.

FIG. 2 shows a top view of a nip W of a high-pressure roller press 100 covered with material to be ground M without side walls 150, 150′, shown here in a view of the grinding rollers 110, 120. The ground material M lays down as a bed on the nip W and covers the nip W. Arrows are drawn on the ground material M, which indicate the approximate flow movement of the ground material M on the Roll gap W show up in the area of the compaction zone. The actual movement of a ground material particle is not necessarily the length of the arrows, but can also only move a fraction of it along the paths of the arrows. To the right of the sketch in FIG. 2, a diagram is shown that represents the possible pressure p in the nip W as position x along the nip W. In this open high-pressure roller press, the pressure drop in the nip W towards the ends is very large, so that the pressure in the nip W in the area of the roll ends drops sharply by more than 50 MPa. As a result, there is no longer any efficient comminution by compaction in the area of the roller gap ends.

FIG. 3 shows a plan view of a nip W of a high-pressure roller press 100 covered with material to be ground M, with static side walls 150, 150′, shown here in a view of the grinding rollers 110, 120. The pressure drop in the nip W to the roll shoulder, ie in the area of one end of the nip, is significantly reduced compared to the arrangement in FIG. 1, but is still present. This effect is called the "edge zone effect". This effect is partly caused by the friction on the sidewall. The sidewall forms a flow barrier and the resulting friction increases with increasing baling pressure because the back pressure on the sidewall surface increases. The stronger the material from the gap is pressed against the side wall, the greater the coefficient of friction and thus less material flows into the edge zone of the gap. This reduces the material bed compression and thus the resulting pressure in the edge zone accordingly. This tends to lead to an approximately bell-shaped pressure distribution along the nip.

FIG. 4 shows a plan view of a nip W of a high-pressure roller press 100 according to the invention, covered with material to be ground M, with vibrating side walls 150, 150′, shown here in a view of the grinding rollers 110, 120. The vibration is generated by a vibration device 160, the intensity is optionally controlled by a control device 170. Due to the side wall (150, 150') vibrating in each case, the pressure at the ends of the roller gap W remains in place because the material to be ground M can flow unhindered into the roller gap W. The vibration helps the material to be ground M in the nip passage.

The unimpeded flow of material along the entire width of the roll ensures a uniform pressure profile and uniform wear of the grinding rolls 110 and 120, so that the narrowing is not so pronounced.

High-pressure roller press A axis grinding roller M regrind grinding roller W nip side wall ' side wall vibration device ' vibration device control device

Claims

1. High-pressure roller press (100) for comminuting brittle ground material (M), having at least two grinding rollers (110, 120) arranged next to one another and rotating in opposite directions, which form a roller gap (W) between them, with a first grinding roller (110) is a fixed roller and a second grinding roller (120) is a loose roller, and one side wall (150, 150') each at the two ends of the roller gap (W), characterized in that each side wall (150, 150') a vibration device (160) which causes mechanical vibrations in each of the side walls (150, 150').

2. High-pressure roller press according to claim 1, characterized in that the vibration device (160) works with a frequency between 10 Hz and 150 Hz, preferably with a frequency between 10 Hz and 60 Hz and an energy input between 0.1 kJ/m ³ and 10 kJ/m ³ , preferably between 0.1 kJ/m ³ and 1.0 kJ/m ³ , into the ground material (M).

3. High-pressure roller press according to one of claims 1 or 2, characterized in that the vibration device (160) has a control device (170) which controls the vibration intensity according to the energy consumed for operation, with increased energy consumption resulting in a reduction in vibration intensity and a reduced Energy absorption results in an increase in vibration intensity.

4. The high-pressure roller press according to claim 3, characterized in that the control device (170) additionally regulates according to the energy consumption of a roller drive, with increased energy consumption of the roller drive resulting in a reduction in vibration intensity and reduced energy consumption in an increase in vibration intensity.

5. High-pressure roller press according to one of claims 3 or 4, characterized in that the vibration device (160) is additionally regulated according to the gap width of the roller gap (W), with an increased gap width resulting in an increase in the vibration intensity and a reduced gap width in a Ver reduction in vibration intensity.

6. High-pressure roller press according to one of Claims 3 to 5, characterized in that the vibration device (160) is additionally controlled according to the inclination of the floating roller (120) to rotate about a vertical axis (A), with the torsional vibration frequency of the floating roller (120 ) the vibration intensity is increased and vice versa.

7. High-pressure roller press according to one of claims 1 to 6, characterized in that a manual triggering device for the vibration device (160) is provided.