Identification of support rollers of a belt conveyor with spatial misalignment

Abstract

The invention relates to a method (100) for identifying support rollers (1) of a belt conveyor (2) with spatial misalignment, wherein the belt conveyor (2) has at least two support rollers (1) oriented parallel to one another and a belt (3) which is supported at least partially on the support rollers (1). In the method (100), at least a rotational speed of at least two support rollers (1) arranged one behind the other in the conveying direction is detected.

Description

[0001] Identification of support rollers of a belt conveyor with spatial misalignment

[0002] The invention relates to a method for identifying support rollers of a belt conveyor with a spatial misalignment, wherein the belt conveyor has at least two support rollers aligned parallel to one another and a belt supported at least partially on the support rollers.

[0003] Belt conveyors are used in a wide variety of industries to enable the efficient and continuous movement of materials. Applications range from the transport of bulk materials such as coal, ore, and grain to the transportation of parcels, luggage, or building materials.

[0004] A belt conveyor typically comprises a belt that circulates continuously between one or more reversing stations and / or drive stations. The materials to be transported are placed on the belt, and the rotation of the drive stations causes the belt to move, carrying the materials along. The belt is supported by a plurality of support rollers arranged between the reversing stations or drive stations.

[0005] Belt conveyor malfunctions are often caused by defective or spatially misaligned idlers. Spatially misaligned idlers, particularly those that are vertically misaligned or have a vertical component, often cause the belt to skew and / or overload individual idlers. This frequently results in bearing damage to the idler bearings. Spatially misaligned idlers are therefore a frequent cause of belt conveyor malfunctions. For example, overloading a idler can result in increased heat generation, which in the worst case can lead to an open fire.

[0006] Methods for identifying defective idlers are known in practice. Such idlers are identified based on increased noise emissions or elevated temperatures, particularly in the presence of smoke or open flames. However, these methods are complex and often involve replacing intact idlers in addition to the defective ones. Furthermore, the idlers are only replaced when they are already defective. The object of the invention is therefore to overcome the aforementioned disadvantages and to provide a method and an improved belt conveyor by means of which idlers with spatial misalignment can be identified with the least possible effort before they become damaged.

[0007] In a first aspect, this object is achieved by a method for identifying support rollers of a belt conveyor with a spatial misalignment, wherein the belt conveyor has at least two support rollers aligned parallel to one another and a belt supported at least partially on the support rollers, which method comprises the following steps: a) detecting at least the rotational speed of at least two support rollers arranged one behind the other in the conveying direction; b) comparing at least the detected rotational speeds; and c) evaluating the comparison, wherein a support roller is identified as a support roller with a spatial misalignment if, when evaluating the comparison, it has at least a higher rotational speed than the at least one other support roller.

[0008] The general task of the support rollers of a belt conveyor is to support the weight of the belt and the load. They therefore ensure the lowest possible friction movement of the belt and guide the belt in a specified position. Support rollers can therefore be designed uniformly in terms of diameter, length, and material. Furthermore, they can be arranged at a uniform distance from one another and on or in a particularly straight or at least continuous path or plane in order to provide ideal support for the belt. In the context of the invention, the term "spatial" misalignment is always understood as having a vertical component.A spatial vertical misalignment, for example an arrangement of at least one bearing of a support roller that is too high compared to the path or plane of the belt, leads to an increased load on this support roller due to local belt tensile forces and can therefore be the cause of bearing damage and increased bearing resistance. Spatial horizontal misalignments (with or without a vertical component) compared to the path or plane of the belt can lead to skewed belt travel and to wear on the casing of the support rollers. Two support rollers arranged one behind the other in the conveying direction can, for example, be arranged directly adjacent to one another. It is also conceivable for them to be arranged only in spatial proximity to one another, so that, for example, one or more support rollers can be arranged between them whose rotational speed is not recorded or is not included in the comparison and / or evaluation.

[0009] The method according to the invention is based on the finding that the local load on a support roller influences the rotational speed, or rather the peripheral speed, of this support roller. Therefore, an increased local load on a support roller leads to a higher rotational speed of this support roller, particularly due to an increased coefficient of friction between the belt and this support roller. For example, in a garland support roller station, this applies to both the side and center rollers.

[0010] Conversely, the rotational speed of a support roller can be used to determine its local load. The load of at least two support rollers arranged correctly one behind the other in the conveying direction is identical, at least when a belt conveyor is operating without any materials to be transported, in particular bulk material. When a belt conveyor is operating with materials to be transported, in particular bulk material, this also applies, at least on average. In this respect, the rotational speed of these support rollers must also be identical. If one support roller has a higher rotational speed than another support roller which is subject to the same load from the materials to be transported, it can be concluded that the local load on one of the faster rotating support rollers is higher than on the other, slower rotating support roller.A spatial misalignment of a support roller, particularly a vertical misalignment of a support roller, causes an increased local load on this support roller due to the resulting local belt tensile forces. Due to the increased local load on this support roller, this support roller will also exhibit an increased rotational speed according to the relationship described above. This spatially misaligned support roller can be identified based on the increased rotational speed.

[0011] The relationship described above between the local load on a support roller and its rotational speed depends on the coefficient of friction between the belt and the corresponding support roller. The coefficient of friction between the belt and the support rollers of a belt conveyor can fluctuate under real-life conditions, particularly under different weather conditions. However, these fluctuations then affect all support rollers of this belt conveyor, so the relationship between the local load and the rotational speed of a support roller is the same for all support rollers, regardless of the actual coefficient of friction.

[0012] Taking the causal relationship described above into account, the method can be carried out, for example, as follows: First, the rotational speed of at least two support rollers arranged one behind the other in the conveying direction is recorded. This can be done, for example, using one or more electromagnetic or optical sensors. The recorded rotational speeds are then compared with one another, for example in a computing unit, and this comparison is evaluated. The comparison determines which of the support rollers has a higher rotational speed. If a support roller has a higher rotational speed, it can be concluded, according to the causal relationship described above, that this support roller is subject to an increased local load. Due to the increased local load on this support roller, it can in turn be concluded that the support roller is misaligned.In the evaluation following the comparison, such a support roller, i.e. a support roller with an increased rotational speed, is identified as a support roller with a spatial misalignment.

[0013] Furthermore, when comparing the recorded rotational speeds, an average of the recorded rotational speeds can be determined, and the rotational speed of each support roller can be compared with the determined average of the recorded rotational speeds. For example, the arithmetic mean, the geometric mean, and / or the root mean square can be determined. The mean, for example, the arithmetic mean, can be determined based on all recorded rotational speeds. The determined rotational speed of each support roller can then be individually compared with this average. Such a comparison with an average allows for a more precise result when detecting an increased rotational speed.

[0014] To further improve the comparison result, the rotational speed of at least three support rollers, for example, four to ten support rollers, and in particular more than ten support rollers, can be recorded. Subsequently, an average value can be determined based on all determined rotational speeds, and the determined rotational speed of each support roller can be individually compared with this average value. By increasing the total number of determined rotational speeds in this way, a more precise result can be achieved when detecting an increased rotational speed.

[0015] During the evaluation, a support roller can be determined as having a higher rotational speed if its rotational speed is at least 0.01%, in particular at least 1%, higher than the determined mean of the recorded rotational speeds. Therefore, if a mean value was used as the basis for the comparison, even a small percentage deviation from the mean value can be assumed to be an increased rotational speed. Such a measurement requires a precise speed measurement designed to reliably measure a deviation in the circumferential speed, particularly in a range of 0.5 to 4 per thousand.

[0016] In addition, variable operating parameters of the belt conveyor can be used in the evaluation of the comparison, in particular a local belt speed, a local belt tensile force and / or a proportion of the load from the load. The local belt speed can, for example, affect the rotational speed of the corresponding support roller. The same applies, for example, to system-specific but constant belt properties. The local belt tensile force can, for example, influence the local load on the support rollers. An increased local belt tensile force can, for example, result in an increased local load on the corresponding support roller. The local proportion of the load from the load can, for example, influence the local load on the support rollers. An increased proportion of the load from the load can, for example, result in an increased local load on the corresponding support roller.Knowledge of the local belt tension and the resulting belt speed are advantageous for applicability. A digital twin, i.e., a calculation of the operating conditions, of the belt system can be used for this purpose. This digital twin calculates the belt tension along the entire system at any time from the speed and belt tension measured at a specific location, taking into account the current load distribution, engine power, the system's elevation profile, and the ambient temperature. From this, the belt speeds along the entire system can be calculated from the belt's modulus of elasticity. Only then can the desired useful information regarding misalignment be isolated from the measured circumferential speeds of individual idlers.

[0017] The variable operating parameters can be recorded by sensors arranged on the belt conveyor and made available for evaluation. For example, a pressure sensor or shear stress sensor and / or a displacement sensor can be arranged on the surface or inside of the belt. The measurement results from such sensors can be used, for example, to calculate the circumferential force of support rollers. Furthermore, an accelerometer can be arranged on the surface or inside of the belt. An optical sensor unit, such as a light barrier, can also be provided to detect the belt speed.

[0018] In another embodiment of the method, the variable operating parameters can be provided for evaluation by a digital twin of the belt conveyor. A digital twin can refer to a virtual representation of a physical belt conveyor. Such a digital twin can include detailed real-time data, such as the aforementioned variable operating parameters of the belt conveyor. It can also include various information sources, including, for example, sensor data of operating parameters and historical records.

[0019] In one embodiment of the method, the recorded rotational speeds can be recorded over a predetermined period of time and averaged over this period and / or the method can be carried out continuously during operation of the belt conveyor. For example, the recorded rotational speeds of each support roller can be recorded and averaged for a predetermined period of time, for example several seconds or several minutes. In this respect, an average value, for example an arithmetic mean, can be determined for each support roller over a predetermined period of time. Such an average value can be regarded as more precise than a snapshot, since short-term fluctuations in the rotational speeds have little influence on the average value. A predetermined period of time can, for example, also comprise several hours, an entire operating shift or a period extending beyond this.It is also conceivable that the time-averaged rotational speeds of each support roller are subsequently averaged to form a common average for all support rollers. The time-averaged rotational speed of each support roller can then be individually compared with this common average for all support rollers. Such a comparison with an average allows for a more precise result in detecting an increased rotational speed.

[0020] In a further advantageous embodiment, the measured speeds are standardized with the corresponding loads and belt tensile forces from a simulation calculation, the digital twin. A conversion to speeds of a reference load and reference belt tensile force takes place before they are compared.

[0021] The rotational speed of at least one support roller can be detected by a sensor unit arranged in this support roller and / or the rotational speed of at least one support roller can be detected by measuring the rotational speed of this support roller, in particular by an externally arranged sensor. A sensor unit arranged in a support roller can, for example, comprise a stator and a rotor, with the stator and rotor interacting electromagnetically. Such a sensor unit can, for example, detect the rotational speed of a support roller. However, it is also conceivable for a sensor unit to comprise, for example, an acceleration sensor and / or a gyrometer.Furthermore, such a sensor unit arranged in or outside the support roller can comprise a communication unit by means of which the detected rotational speeds can be wirelessly transmitted to at least one further communication unit and / or a storage unit by means of which the detected rotational speeds can be documented. In one example, the rotational speeds detected by the sensor unit can be transmitted to an external storage unit by means of the communication unit. These transmitted rotational speeds can be used, for example, to create a digital twin of the respective support roller.

[0022] Determining the rotational speed of a support roller by measuring its speed can be a technically simple method for determining its rotational speed. In order to determine the rotational speed of a support roller from its speed, the diameter of the respective support roller must be known. It is also conceivable to compare the rotational speeds directly based on the speeds of the support rollers. However, this requires that the compared support rollers have an identical diameter.

[0023] Furthermore, when a support roller with a spatial misalignment is identified, a signal can be output via a signaling unit. A signaling unit can, for example, be designed as an LED light arranged on the corresponding support roller or as an acoustic signaling unit arranged on the belt conveyor. It is also conceivable for the signal to be output on a screen unit. Such a screen unit can, for example, be used to output operating parameters of a digital twin. Through early identification of a spatially misaligned support roller in combination with the output of a corresponding signal via a signaling unit, spatially misaligned support rollers can be realigned or, if necessary, replaced before bearing damage or a belt conveyor failure occurs.

[0024] In a further aspect, a belt conveyor for bulk material is proposed for carrying out at least one embodiment of the aforementioned method, comprising at least one flexible belt that endlessly circulates between reversing stations and / or drive stations, wherein the belt is at least partially supported between the reversing station(s) and / or drive station(s) on a plurality of support rollers, wherein at least one sensor unit is provided for determining the rotational speed of at least two support rollers. At least one computing unit is provided, which is designed to carry out a comparison of the detected rotational speeds, to evaluate the comparison, and to identify at least one support roller with a spatial misalignment.

[0025] At least one sensor unit, preferably each sensor unit, can be arranged on or within the support roller assigned to it to determine the rotational speed. It is also conceivable for a sensor unit, for example an optical sensor unit, to be designed to determine the rotational speed of several support rollers. A sensor unit arranged in a support roller can, for example, comprise a stator and a rotor, with the stator and rotor interacting electromagnetically. Such a sensor unit can, for example, detect the rotational speed of a support roller. However, it is also conceivable for a sensor unit to comprise, for example, an acceleration sensor and / or a gyrometer.Furthermore, such a sensor unit can also comprise a communication unit by means of which the detected rotational speeds can be transmitted wirelessly to another communication unit and / or comprise a storage unit by means of which the detected rotational speeds can be documented.

[0026] A method is also advantageous, wherein the variable operating parameters are provided by at least three sensors integrated into the belt, wherein the sensors are designed as tension sensors and the measured values ​​of the sensors are made available for evaluation.

[0027] A plurality of tension sensors integrated or embedded in the belt can advantageously provide various additional information. This information can advantageously be used to improve operational reliability. Furthermore, these sensor measurements can enable an improved prediction of a failure point and / or identify technical problems with the belt conveyor system. In a particularly advantageous embodiment of the belt conveyor, tension sensors are embedded in the belt. The tension sensors use measurements based on the piezoelectric effect and measure the strain in the layer in which they are incorporated.

[0028] Piezo sensors deliver a voltage signal whose magnitude and profile depend on the magnitude and speed of the deformation. Piezo foils are particularly suitable for integration into the belt, as they can be made very thin and therefore do not influence the deformation being measured. The piezo foils can be designed to have a preferred direction, meaning that deformation in this direction generates a significantly higher signal than deformation perpendicular to this preferred direction.

[0029] It is particularly advantageous to integrate at least 3 to 30 tension sensors into the belt as a sensor set across the width of the belt. Preferably, several sensor sets are arranged along the length of the belt conveyor, allowing short-term events to be better mapped and the failure of individual sensors or sensor sets to be compensated for. A sensor set preferably includes locally located sensors, a power supply, and a communication unit.

[0030] Advantageously, the tensile force in the conveyor belt can be recorded over time. This allows differences in tensile forces across the width of the conveyor belt to be identified. The values ​​from the tension sensors are also advantageously evaluated via a link to the current locations. This allows the data to be evaluated at the moment the sensor set passes a specific support roller.

[0031] The tension sensors in the belt can advantageously provide information for detecting belt misalignment. In particular, the position of the tension sensors in relation to the support roller is advantageously evaluated.

[0032] Furthermore, an evaluation of the tension sensors in the belt conveyor in one embodiment of the belt conveyor can advantageously provide information on the drums, both for driven and non-driven drums, for the method according to the invention.

[0033] This allows the wear of the drum surface to be calculated directly from tension differences across the belt width. This allows for targeted maintenance and / or repair planning. Furthermore, an alarm can be triggered in the event of excessive wear. For drum surface analysis, it is advantageous to integrate multiple sensors into a sensor set, particularly preferably at least 7 to 70 tension sensors.

[0034] In another particularly advantageous embodiment, two tension sensors are arranged one above the other. "Stacked" means that at least one point in a sensor set, two tension sensors are arranged one above the other across the thickness of the belt, at the same position in the running direction and the transverse direction. This advantageously allows the belt's curvature radii to be determined based on the tension differences in the various belt layers. Belt sag between the idlers can advantageously be calculated, and belt sag is calculated. Furthermore, the belt tensile force along the system can be calculated as a curve, and the loading and height curves can also be evaluated in a digital twin using a calculation.

[0035] In one embodiment of the belt conveyor, at least one storage unit for recording the determined rotational speeds and / or at least one storage unit for recording the evaluation can be provided. The recorded values ​​can then be used, for example, in a digital twin of the belt conveyor.

[0036] In a further embodiment of the belt conveyor, at least one signal unit can be provided for outputting a signal upon identification of a support roller with a spatial misalignment. A signal unit can be designed, for example, as an LED light arranged on the corresponding support roller or as an acoustic signal unit arranged on the belt conveyor. It is also conceivable for the signal to be output on a screen unit. Such a screen unit can, for example, be used to output operating parameters of a digital twin. Through early identification of a spatially misaligned support roller in combination with the output of a corresponding signal via a signal unit, spatially misaligned support rollers can be realigned or, if necessary, replaced before bearing damage or a belt conveyor failure occurs.

[0037] The following figures illustrate exemplary embodiments of the invention. They show:

[0038] Fig. 1 is a schematic representation of an example of a method according to the invention,

[0039] Fig. 2 is a schematic representation of an example of a belt conveyor,

[0040] Fig. 3 is a schematic representation of another example of a belt conveyor, and Fig. 4 is a schematic representation of the relationship between local load and the rotational speed of a support roller.

[0041] In all figures, identical reference symbols are used for identical or similar elements.

[0042] Fig. 1 shows a schematic representation of an exemplary method 100 for identifying support rollers 1 of a belt conveyor 2 with a spatial misalignment, wherein a belt conveyor 2 comprises at least two support rollers 1 aligned parallel to one another and a belt 3 supported at least partially on the support rollers 1. The method 100 comprises the following steps, which can be carried out successively, for example:

[0043] In a first step a), at least the rotational speeds of at least two support rollers 1 arranged one behind the other in the conveying direction are recorded. The rotational speed of a support roller 1 is recorded, for example, by a sensor unit 6 arranged inside a support roller 1. Such a sensor unit 6 can, for example, record the rotational speed of the corresponding support roller 1, for example by means of a gyrometer. Furthermore, such a sensor unit 6 can comprise a communication unit, by means of which the recorded rotational speeds can be transmitted, in particular wirelessly, to a further communication unit 7 and / or computing unit 8, as is shown in Fig. 1 by way of example for the right-hand support roller 1. The exemplary computing unit 8 has at least one memory unit 9 for recording the determined rotational speeds and / or for recording the evaluation.

[0044] In a second step b), the detected rotational speeds are compared, for example, by means of the computing unit 8. In such a comparison, either two or more detected rotational speeds can be compared directly, or individual detected rotational speeds can be compared with a determined average value of several detected rotational speeds.

[0045] For example, the recorded rotational speeds of each support roller 1 can be recorded and averaged for a predetermined period of time, for example, several seconds or several minutes. A predetermined period can also comprise several hours, an entire operating shift, or a longer period. In this respect, an average value, for example an arithmetic mean, can be determined for each support roller 1 over the predetermined period. It is also conceivable that the time-averaged values ​​of the rotational speed of each support roller 1 are subsequently averaged to form a common mean value for all support rollers 1. The time-averaged values ​​of the rotational speed of each support roller 1 can then be individually compared with this common mean value.

[0046] In a third step c), the comparison from step b) is evaluated. A support roller 1 is identified as a support roller 1 with a spatial misalignment if it has at least a higher rotational speed in the comparison from step S2. If the rotational speeds of a support roller 1 were compared with an average value during the comparison, a support roller 1 can be determined in an evaluation as having a higher rotational speed if its rotational speed is at least 5%, preferably at least 10%, higher than the determined average value of the recorded rotational speeds. Therefore, if, for example, an average value was used as the basis for the comparison, even a small percentage deviation from the average value can be assumed to be an increased rotational speed.

[0047] In an optional step d), if a support roller 1 with a spatial misalignment was identified during the evaluation from step c), a signal can be output via a signal unit 10. A signal unit 10 can be designed, for example, as an optical or acoustic signal unit 10 arranged on the computing unit 8, as an LED light arranged on the corresponding support roller 1, or, for example, as an acoustic signal unit arranged on the belt conveyor 2. It is also conceivable for the signal to be output on a screen unit, for example for outputting operating parameters of a digital twin.

[0048] Furthermore, it is advantageous and optional for the method to standardize the measured values ​​using a model calculation, in particular in a digital twin.

[0049] Fig. 2 and Fig. 3 each show an example of a belt conveyor 2 for bulk material for carrying out the method 100 described above. The belt conveyor 2 shown comprises a flexible belt 3 which circulates endlessly between a reversing station 4 and a drive station 5. The belt 3 is supported between the reversing station 4 and the drive station 5 by, in the example shown, nine support rollers 1 arranged one behind the other in the conveying direction.

[0050] Both the belt conveyor 2 shown in Fig. 2 and the one shown in Fig. 3 run horizontally and have neither a slope nor a bend or a wave. The support rollers 1 are designed as cylindrical support rollers that extend across the entire width of the belt 3. Furthermore, all support rollers 1 are identically designed, in particular, they have an identical diameter.

[0051] In Fig. 2 and Fig. 3, for example, a bulk material, such as coal or rock, can be conveyed, for example poured, onto the belt 3 from the side of the respective drive station 5. The bulk material is then transported toward the reversing station 4, following the direction of movement of the belt 3. The belt conveyors 2 shown in Fig. 2 and Fig. 3 are merely schematic and highly simplified.

[0052] In Fig. 2, all support rollers 1 are arranged at exactly the same height. Furthermore, the support rollers 1 are arranged horizontally equidistant. There is no spatial misalignment at any support roller 1, in particular no vertical misalignment. Therefore, all support rollers 1 rotate at the same rotational speed, and none of the support rollers 1 exhibits an increased local load compared to the other support rollers 1.

[0053] In Fig. 3, a support roller 1, the central support roller 1 or the fifth support roller 1 viewed from the left, is arranged somewhat higher than the other support rollers 1. It is therefore not arranged at the same vertical height as the other support rollers 1 and is spatially misaligned and thus also has a vertical component. Due to the spatial misalignment, this support roller 1 has an increased local load and, due to the relationship between the local load and the rotational speed of a support roller 1, also has a higher rotational speed compared to the other support rollers 1. Using, for example, the method 100 described above, this fifth support roller can be identified due to the increased rotational speed. In Fig. 4, several support roller circumferential speed curves are plotted against the percentage utilization of the respective support rollers 1.The percentage utilization refers to the local load on the respective support rollers 1. A distinction is made between the various support roller circumferential speed curves shown according to whether the respective support roller 1 is a side roller or a center roller. Side and center rollers are each part of a garland support roller station, which consists of two laterally arranged side rollers and a center roller arranged centrally between the two side rollers. Viewed in cross-section, such a garland support roller station typically describes a V-shaped or U-shaped profile, with the center roller being mounted lower than the side rollers. Furthermore, a distinction is made between the various support roller circumferential speed curves shown according to whether a friction coefficient of p=0.1, p=0.3 or p=0.6 exists between the respective support roller 1 and the belt 3.As can also be seen in the diagram, the support roller circumferential speed of the center rollers 1a is higher than the support roller circumferential speed of the side rollers 1b due to the higher weight forces acting on them due to their arrangement.

[0054] The coefficient of friction between the belt 3 and the support rollers 1 of a belt conveyor 2 can fluctuate under real-world conditions, particularly under different weather conditions. However, these fluctuations then affect all support rollers 1 of this belt conveyor 2, so that the relationship between the local load and the rotational speed of a support roller 1 is the same for all support rollers 1, regardless of the actual coefficient of friction.

[0055] List of reference symbols

[0056] 1 support roller

[0057] 1a center rollers

[0058] 1 b side rollers

[0059] 2 belt conveyors

[0060] 3 webbing

[0061] 4 reversing station

[0062] 5 drive station

[0063] 6 Sensor unit

[0064] 7 Communication unit

[0065] 8 computing unit

[0066] 9 Storage unit

[0067] 10 signal unit

[0068] 100 procedures

Claims

Claims 1. Method (100) for identifying support rollers (1) of a belt conveyor (2) with a spatial misalignment, wherein the belt conveyor (2) has at least two support rollers (1) aligned parallel to one another and a belt (3) supported at least partially on the support rollers (1), comprising the following steps: a) detecting at least the rotational speed of at least two support rollers (1) arranged one behind the other in the conveying direction; b) comparing at least the detected rotational speeds; c) evaluating the comparison; wherein a support roller (1) is identified as a support roller (1) with a spatial misalignment if, when evaluating the comparison, it has at least a higher rotational speed than the at least one other support roller (1).

2. Method (100) according to the preceding claim, characterized in that in the comparison of the detected rotational speeds, an average value of the detected rotational speeds is determined and the rotational speed of each support roller (1) is compared with the determined average value of the detected rotational speeds.

3. Method (100) according to the preceding claim, characterized in that during the evaluation a support roller (1) is determined as having a higher rotational speed if its rotational speed is at least 0.01%, preferably at least 1%, higher than the determined mean value of the detected rotational speeds.

4. Method (100) according to at least one of the preceding claims, characterized in that variable operating parameters of the belt conveyor (2) are used for the evaluation of the comparison, in particular a local belt speed, a local belt tensile force and / or a proportion of the load from the loading.

5. Method (100) according to the preceding claim, characterized in that the variable operating parameters are detected by sensors (6) arranged on the belt conveyor (2) and made available for evaluation.

6. Method (100) according to at least one of the two preceding claims, characterized in that the variable operating parameters are made available for evaluation by a digital twin of the belt conveyor (2).

7. Method (100) according to at least one of the preceding claims, characterized in that the detected rotational speeds are detected over a predetermined period of time and are averaged over this period of time and / or the method (100) is carried out continuously during the operation of the belt conveyor (2).

8. Method (100) according to at least one of the preceding claims, characterized in that the rotational speed of at least one support roller (1) is detected by means of a sensor unit (6) arranged in this support roller (1) and / or the rotational speed of at least one support roller (1) is detected by measuring the speed of this support roller (1).

9. Method (100) according to at least one of the preceding claims, characterized in that upon identification of a support roller (1) with a spatial misalignment, a signal is output via a signal unit (10).

10. Method (100) according to at least one of the preceding claims, characterized in that the variable operating parameters are provided by at least three sensors (6) integrated into the belt webbing (3), wherein the sensors (6) are designed as tension sensors and the measured values ​​of the sensors (6) are made available for evaluation.

11. Belt conveyor (2) for bulk material for carrying out the method (100) according to at least one of claims 1 to 9, comprising at least one flexible belt (3) which circulates endlessly between reversing stations (4) and / or drive stations (5), the belt (3) being supported at least partially between the reversing stations (4) and / or drive stations (5) on a plurality of support rollers (1), characterized in that at least one sensor unit (6) is provided for determining the rotational speed of at least two support rollers (1) and that at least one computing unit (8) is provided, the computing unit (8) being designed to carry out a comparison of the detected rotational speeds, to evaluate the comparison and to identify at least one support roller (1) with a spatial misalignment.

12. Belt conveyor (2) according to the preceding claim, characterized in that at least one storage unit (9) is provided for recording the determined rotational speeds and / or at least one storage unit (9) is provided for recording the evaluation.

13. Belt conveyor (2) according to one of the two preceding claims, characterized in that at least one signal unit (10) is provided for outputting a signal upon identification of a support roller (1) with a spatial misalignment.

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