Arrangement and method of a tube-bundle reactor and a sensor device

Abstract

The present invention relates to an arrangement of a tube-bundle reactor (1) and a sensor device (2), wherein the tube-bundle reactor (1) comprises a bundle of vertically arranged reaction tubes (3) which are upwardly open by means of upper openings and are fillable with particles of a catalyst material (4). The sensor device (2) comprises an ultrasonic sensor (6) and an evaluation device (7), wherein the ultrasonic sensor (6) is designed to transmit an ultrasonic signal into one of the reaction tubes (3) from above and to receive the ultrasonic signal reflected in the reaction tube (3). The evaluation device (7) is coupled to the ultrasonic sensor (6) via a data connection (8) and designed to determine, from the reflection time of the received ultrasonic signals, the distance from the surface of the particles of the catalyst material (4) accommodated by the one reaction tube (3) to the ultrasonic sensor (6) and, from this, a fill level of the catalyst material (4) in the reaction tube (3).

Description

[0001] BASF SE 210056W001

[0002] 1

[0003] Arrangement and method of a tube bundle reactor and a sensor device

[0004] The present invention relates to an arrangement of a tube-bundle reactor and a sensor device, wherein the tube-bundle reactor comprises a bundle of vertically arranged reaction tubes, which are open at the top through upper openings and can be filled with particles of a catalyst material. Furthermore, the invention relates to a method for determining the fill level of a catalyst material in the reaction tubes of a tube-bundle reactor using such an arrangement.

[0005] Catalyst loading of a tube-bundle reactor is a very important step for reactor performance. Among other parameters, uniform loading of all reaction tubes is a prerequisite for optimal yield of the products produced by the reactor.

[0006] DE 10 2006 013 488 A1 describes a tube bundle reactor feeding device for this purpose, which has dosing chambers that can be filled with filling material, such as catalytically coated carrier material, wherein a tube of the tube bundle reactor can be filled via a feed device that is connected to the dosing chamber.

[0007] However, to ensure uniform filling, the fill levels of all reaction tubes must be carefully checked after the catalyst filling process. Currently, the fill level is determined by manually inserting a dipstick into each tube. Since a tube-bundle reactor typically has 20,000 to 40,000 tubes, this process is laborious and time-consuming, requiring a high level of attention and motivation from the personnel involved. Furthermore, there is a risk of catalyst damage if the dipstick is placed too tightly on the catalyst.

[0008] The present invention is therefore based on the object of providing an arrangement and a method of the type mentioned above, with which the fill level of the particles of the catalyst material in a tube bundle reactor can be determined more quickly, more cost-effectively and less prone to errors.

[0009] According to the invention, this object is achieved by an arrangement having the features of claim 1 and by a method having the features of claim 12. Advantageous embodiments and further developments emerge from the dependent claims.

[0010] M / 62016-PCT BASF SE 210056W001

[0011] 2

[0012] The arrangement according to the invention for the tube bundle reactor described at the outset comprises a sensor device which comprises an ultrasonic sensor and an evaluation device, wherein the ultrasonic sensor is designed to emit an ultrasonic signal from above into one of the reaction tubes and to receive the ultrasonic signal reflected in the reaction tube, and wherein the evaluation device is coupled to the ultrasonic sensor via a data connection and is designed to determine the distance of the surface of the particles of the catalyst material picked up by the one reaction tube from the ultrasonic sensor and therefrom the fill level of the catalyst material in the reaction tube from the propagation time of the received ultrasonic signals.

[0013] The tube-bundle reactor is a chemical reactor in which highly exothermic reactions, usually oxidation reactions, are carried out in the gas phase. The gas mixture is converted in reaction tubes, which may be surrounded by a coolant, with the aid of a catalyst.

[0014] The reaction tubes contain a catalyst material that consists primarily of individual particles. The particles typically have a spherical, solid-cylindrical, or hollow-cylindrical geometry. The diameter-to-length ratio of the particles is usually in the range of 0.4 to 1.5, and the ratio of particle size to tube diameter is generally 1:15 to 1:3. The catalyst typically consists of mixtures of (noble) metals, mixed metal oxides, or ceramic base materials such as oxides of silicon, magnesium, aluminum, and titanium. In some cases, the catalyst consists of only one component. During operation of the tube bundle reactor, the activity and selectivity of the catalyst material usually decrease over time, requiring regular catalyst replacement. For optimal reactor yield, the aim is to achieve as perfect synchronization as possible among all reaction tubes in a tube bundle reactor.To achieve this synchronization, the quality of the filled catalyst particles must be as consistent as possible throughout the entire filling batch. Quality characteristics here include the intrinsic activity and selectivity of the catalyst mass, geometric parameters of the catalyst particles such as size and shape or their distribution, and mechanical properties such as the fracture strength of the filled catalyst particles. To ensure a uniform flow of reactants through the individual reaction tubes, the filling quantity and filling rate during filling of the reactor must be kept very constant in order to achieve the most uniform filling level possible. While the geometric, catalytic and

[0015] M / 62016-PCT BASF SE 210056W001

[0016] 3 fracture mechanical properties are checked or adjusted in upstream tests during catalyst production, the homogeneous filling of the reaction tubes must be checked after the filling process, for which purpose the arrangement is used.

[0017] For this purpose, according to one embodiment of the inventive arrangement, the ultrasonic sensor is located directly above the opening of the reaction tube. The small distance between the emitting surface of the ultrasonic sensor and the opening of the reaction tube is referred to as the offset. In another embodiment of the inventive arrangement, the ultrasonic sensor is immersed in the reaction tube.

[0018] The emission characteristic of the ultrasonic sensor is an ultrasonic beam. The ultrasonic sensor of the arrangement according to the invention is particularly oriented such that the axis of symmetry of the ultrasonic beam is parallel to the longitudinal axis of the reaction tube of the tube-bundle reactor. Thus, the ultrasonic signal is emitted parallel to the longitudinal axis of the reaction tube of the tube-bundle reactor, centrally into a reaction tube. This advantageously prevents reflections of the ultrasonic signal from the walls of the reactor tube and from protruding contaminants in the reaction tube.

[0019] The signal's propagation time is determined from the time of transmission and the time of reception. These times are detected by the ultrasonic sensor and stored in the evaluation device. The evaluation device determines the fill level from the propagation time. According to one embodiment of the inventive arrangement, it is coupled to a temperature sensor for this purpose, which continuously performs temperature measurements in the vicinity of the reaction tubes in order to determine the temperature-dependent speed of sound required for calculating the fill level.

[0020] The fill level is defined as the distance from the bottom of the reaction tube, on which the catalyst material particles rest, to the upper surface formed by the catalyst material particles. The fill level, on the other hand, is defined as the distance between the surface of the catalyst material particles and the ultrasonic sensor.

[0021] The arrangement according to the invention has the advantage that the filling level of the particles of the catalyst material in a tube bundle reactor can be measured with the aid of an ultrasonic sensor

[0022] M / 62016-PCT BASF SE 210056W001

[0023] 4 can be determined more quickly, more cost-effectively, and with less error. Since the measurement of the fill level of the filled catalyst particles using an ultrasonic sensor is contactless, unlike dipsticks, damage to the filled catalyst particles during the measurement process can be ruled out. The automatic calculation of the fill level simplifies and accelerates the measurement process. Costs are reduced by reducing the employee time required to perform the measurements and minimizing wear and tear on the catalyst material due to damage. Furthermore, the measurement can be performed more frequently with less effort, ensuring optimized catalyst filling, which results in improved yield in the reaction process.

[0024] According to one embodiment of the arrangement according to the invention, the ultrasonic sensor comprises an ultrasonic transducer head with an output surface for emitting the ultrasonic signal. A matching layer is arranged on the output surface to adapt the radiation characteristics of the ultrasonic sensor to the geometry of the reaction tubes.

[0025] When measuring the fill level with an ultrasonic sensor, the problem can arise that fine deposits on the pipe walls cause unwanted reflections of the ultrasonic signal. These distort the reflected signal with additional echoes. The echoes from the deposits can be reduced by using a smaller beam angle.

[0026] For this purpose, commercially available, round, flat ultrasonic transducers can be used. These have an ultrasonic transducer head with an output surface for emitting the ultrasonic signal, which is coated with a matching layer. This additional layer changes the radiation characteristics of the ultrasonic sensor. The matching layer can, for example, reduce the cross-sectional diameter of the ultrasonic beam.

[0027] Advantageously, this allows the radiation characteristics of the ultrasonic sensor to be easily adapted to the pipe geometry. The narrowed ultrasonic beam directs the signal only toward the center of the pipe, reducing reflections at the edge of the pipe or from deposits, thus eliminating inaccurate time-of-flight measurements.

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[0029] 5

[0030] According to a further embodiment of the arrangement according to the invention, the thickness of the matching layer is greater in the center of the coupling surface than at the edge. The thickness of the matching layer can increase abruptly or can also be achieved through a continuous transition in the layer thickness from the outer edge of the coupling surface to the inner layer thickness in the center. Depending on the geometry of the coupling surface, a specific change in the radiation characteristic occurs.

[0031] This arrangement allows for a particularly narrow ultrasonic beam to be generated, the width of which can be optimally adapted to the geometry of the reactor tube. This advantageously further prevents reflections from deposits on the walls of the reflection tube. The ultrasonic signal propagates only in the center of the tube.

[0032] According to a further embodiment of the arrangement according to the invention, the matching layer has a first film that is tightly attached to the output coupling surface. The first film can be, for example, an adhesive film. The use of a film, in particular an adhesive film, ensures that no gaps form between the ultrasonic transducer head and the matching layer. Air pockets in the gaps would cause an unwanted change in the ultrasonic signal due to the material transitions and make reliable signal evaluation more difficult. Furthermore, such adhesive films are inexpensive and available in various designs, for example, in different thicknesses. Attaching them to the ultrasonic transducer head is very simple, and the size of the layer can be easily adjusted as required.

[0033] According to a further embodiment of the arrangement according to the invention, the matching layer has a second foil which is smaller than the first foil and which is fastened on the side of the first foil facing away from the coupling-out surface in the middle of the coupling-out surface, so that the thickness of the matching layer is greater in the middle of the coupling-out surface than at the edge.

[0034] The ratio of the diameter of the smaller second foil to the diameter of the larger first foil is in particular in a range from 0.16 to 0.36, in particular this ratio is 0.26. Accordingly, the ratio of the area of ​​the smaller second foil to the area of ​​the larger first foil is in a range from 0.026 to 0.013, preferably 0.07. A matching layer designed in this way can prevent measurement errors due to adhesions or incrustations on the inner walls of a reaction tube.

[0035] M / 62016-PCT BASF SE 210056W001

[0036] 6

[0037] By using films, especially two adhesive films, there are no gaps between the ultrasonic transducer head, the first film, and the second film. The ultrasonic signal is therefore not distorted by air pockets between the material transitions. Furthermore, the two films can be attached to the transducer head very easily, especially if they are adhesive films. The material of the two films can be variably selected in order to optimally adapt the radiation characteristics to the existing properties of the reaction tubes. Different materials and thicknesses can also be selected for the first and second films. The radius of the second film can also be freely selected. This makes it possible to create different ratios of the thickness of the film in the middle and the thickness of the film in the edge area, as well as different ratios of the radii of the first film to the second film.

[0038] This advantageously creates a modified radiation characteristic of the ultrasonic beam in a very simple and cost-effective manner, which is particularly well adapted to the measuring task, in particular to the geometry of the reaction tube.

[0039] According to a further embodiment of the arrangement according to the invention, the sensor device has an indicator which is designed to display an optical signal which is dependent on the determined fill level of the evaluation device.

[0040] The desired fill level or an approved range for the fill level can be stored in advance in the evaluation unit of the sensor device. After the measurement has been completed, this target value is compared with the measured actual value of the fill level. An optical signal indicates whether the measurement result is within the specified range. This can be done, for example, using a strip of light-emitting diodes (LEDs). For this purpose, three differently colored LEDs are arranged on the ultrasonic sensor. If the fill level is within the desired target range, a green LED lights up; if it is outside, i.e. below or above the selected range, a red LED lights up. Furthermore, a yellow light can be used to signal if no measured value could be determined. This is the case, for example, if there were reflections from impurities that prevented evaluation.If the fill level is too low and / or the ultrasonic signal is too powerful to receive a sufficient reflected signal, this is indicated by the yellow light. If the fill level is too high, the reflected signal cannot be reliably evaluated.

[0041] M / 62016-PCT BASF SE 210056W001

[0042] 7 This area is also called the "blind zone." Here, the reflected signal arrives at the ultrasonic sensor so quickly that it is still in the dead time after the signal has been transmitted. A yellow LED is also displayed in this case. Additionally, the fill level reading in mm can be output via a display on the ultrasonic sensor.

[0043] This arrangement advantageously allows for quick detection of the fill level and any measurement errors. The result of each measurement is displayed until the next measurement is started. This allows sufficient time to check the measurement and, if necessary, stop the measuring process to correct the fill level or start a new measurement.

[0044] In one embodiment of the arrangement according to the invention, the sensor device alternatively or additionally comprises a component for generating an acoustic signal, which is designed to generate an acoustic signal. If the fill level is detected as being below or above the desired value or as not measurable, i.e., when the red or yellow LED is displayed, a short warning tone also sounds, for example, via a loudspeaker. This enables even simpler and more automated checks of the fill levels.

[0045] According to a further embodiment of the arrangement according to the invention, the ultrasonic sensor is attached to a measuring carriage, which is mounted on a rail system above the openings of the reaction tubes and is movable in a horizontal plane above the openings of the reaction tubes. The measuring carriage is moved, in particular, on profiled rollers for more precise guidance. The carriage can move continuously; in particular, it is not stopped when measuring with the ultrasonic sensor.

[0046] The measurement is started when the ultrasonic sensor is positioned in a central area above a reaction tube during continuous movement of the measuring carriage. A speed monitor is installed on the measuring carriage. Due to the small tube diameter, the carriage must not move too fast, allowing sufficient time for the measurement. The measuring carriage can be moved manually or automatically on the rail system. If the measuring carriage is moved too quickly manually, or if the correct measuring position cannot be achieved during automatic movement, an alarm sounds.

[0047] M / 62016-PCT BASF SE 210056W001

[0048] 8

[0049] The advantage of the measuring carriage is that the ultrasonic sensor is aligned to the reaction tubes. This eliminates the need to recalibrate for each individual measurement. This is particularly important because if the sensor is incorrectly aligned, the ultrasonic waves can be reflected by the tube casing or dirt deposits there, making the measurement impossible. The measuring carriage therefore makes the measurement less error-prone overall. Alignment on the rail system, or the continuous feed, makes the measurement time very efficient.

[0050] According to a further embodiment of the arrangement according to the invention, the sensor device comprises a rechargeable battery designed to ensure the power supply of the sensor device. A battery module is mounted on the measuring carriage, which supplies power to both the measuring carriage and the ultrasonic sensor. This allows the arrangement to function without a direct connection to the power grid. When no fill level measurements need to be performed, the battery can be charged.

[0051] According to a further embodiment of the arrangement according to the invention, the arrangement comprises an alignment device with light barrier sensors, which is designed to detect the relative position of the ultrasonic sensor to the reaction tube in a horizontal plane.

[0052] In addition to the light barrier sensors, the alignment device can include a calculation unit. When the sensor device is moved, the light barrier sensors detect the relative position of the ultrasonic sensor to the reaction tube. From this, the calculation unit calculates how the ultrasonic sensor must be moved using the measuring carriage in order to align it so that the vertical axis of the ultrasonic traveling head coincides with the longitudinal axis of the reaction tube.

[0053] To detect the reaction tube, two light barriers offset from each other in the direction of travel are combined into a pair. The offset of the light barriers is approximately 5 mm less than the tube diameter. As long as both light barriers detect the tube opening simultaneously, the distance measurement is triggered and released. To reliably detect the tube openings, there are two pairs of these light barriers, which are connected in an OR gate.

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[0055] 9

[0056] The light barrier pairs advantageously enable automated start of the fill level measurement, namely when the ultrasonic sensor is positioned directly above the permitted interior area of ​​the reaction tube. The use of the light barrier pairs thus further increases the degree of automation of the measurement and reduces its susceptibility to errors.

[0057] According to a further embodiment of the arrangement according to the invention, the sensor device comprises a plurality of ultrasonic sensors.

[0058] By installing the alignment device with a measuring carriage, calculation unit, and pairs of light barriers, the measurement is so highly automated that it is possible to measure the fill levels of several reaction tubes simultaneously. Several ultrasonic sensors are located on the measuring carriage, arranged, for example, in a row. Each ultrasonic sensor is assigned LEDs and a display to indicate the fill level, as described above. This is particularly advantageous because a tube-bundle reactor contains several thousand reaction tubes, whose fill level measurement can be completed significantly faster by performing measurements on several reaction tubes simultaneously.

[0059] According to a further embodiment of the arrangement according to the invention, the reaction tubes in the tube bundle reactor are arranged in a uniform grid or a uniform tube pitch, resulting in a recurring linear pattern.

[0060] A grid is a regular pattern distributed over a surface. The grid is formed by repeatedly shifting this pattern in a horizontal plane. The reaction tubes are arranged horizontally in such a way that the same pattern is always apparent in at least one direction during horizontal movement across the tube openings.

[0061] Advantageously, this makes it easy to find a structured sequence of reaction tube selection during the measurement process.

[0062] According to a further embodiment of the arrangement according to the invention, the ultrasonic sensors are arranged on the measuring carriage in such a way that they correspond to the recurring linear pattern of the grid of the reaction tubes.

[0063] M / 62016-PCT BASF SE 210056W001

[0064] 10

[0065] Ultrasonic sensors are aligned on the measuring carriage in such a way that when the measuring carriage moves in the direction of the recurring pattern, the ultrasonic sensors are moved over the openings of the reaction tubes. After a certain amount of advance of the measuring carriage, the vertical axis of these ultrasonic sensors coincides with the longitudinal axis of a reaction tube. This relative arrangement of the grid of reaction tubes and the ultrasonic sensors on the measuring carriage enables a linear movement of the measuring carriage without constantly shifting the ultrasonic sensors on the measuring carriage for individual measurements. Furthermore, all reaction tubes can be measured by repeatedly shifting the measuring carriage.

[0066] A large number of ultrasonic sensors can be located on the measuring carriage, all of which experience the same feed rate as the measuring carriage advances, and can therefore be moved across the reaction tubes simultaneously. For example, the ultrasonic sensors are arranged next to each other in a row and at the same distance from each other. This arrangement is mirrored in the reaction tubes, which are also arranged in rows one behind the other. With a uniform feed of the measuring carriage, each row of reaction tubes is traversed and measured one after the other. Advantageously, this allows a large number of reaction tubes to be measured simultaneously, requiring only a linear feed of the measuring carriage and no additional adjustment of the individual ultrasonic sensors. This arrangement therefore leads to a faster and less error-prone measuring process.

[0067] In a further embodiment of the arrangement according to the invention, sound signals from neighboring ultrasonic sensors are attenuated by covering the underside of the measuring carriage in the area of ​​the ultrasonic sensors with fleece or felt, e.g., using an adhesive tape. These damping layers of fleece or felt are attached to the measuring carriage in such a way that they suppress unwanted reflections from other ultrasonic sensors.

[0068] The invention further relates to a method for determining the filling level of a catalyst material in the reaction tubes of a tube bundle reactor with a sensor device comprising an ultrasonic sensor with which an ultrasonic signal is emitted from above into one of the reaction tubes and the ultrasonic signal reflected in the reaction tube is received, and the received signal is transmitted via a data connection to an evaluation device, and the

[0069] M / 62016-PCT BASF SE 210056W001

[0070] 11

[0071] Evaluation device uses the transit time of the received ultrasonic signals to determine the distance between the surface of the catalyst material particles picked up by a reaction tube and the ultrasonic sensor and from this the filling level of the catalyst material in the reaction tube.

[0072] The method according to the invention can be carried out, in particular, by the arrangement according to the invention. It has the same advantages as the arrangement according to the invention.

[0073] As soon as the ultrasonic signal is transmitted using the method according to the invention, the start time of the transmission is transmitted to the evaluation device. The arrival time of the reflected signal at the ultrasonic sensor is also transmitted to the evaluation device. The distance measurement is then performed indirectly via a propagation time measurement of the ultrasonic signal.

[0074] During the level measurement of a reaction tube, several ultrasonic pulses are emitted into the reaction tube. The power of the ultrasonic sensor for emitting the ultrasonic pulses is selected so that a sufficiently large reflection signal can be detected even in empty tubes, i.e., at maximum signal penetration depth.

[0075] Due to the geometry of the catalyst material particles, there is a variance in the fill level at different positions in the reaction tube on the order of magnitude of the catalyst material particles. This variance is not taken into account in the measurement because the size of the particles and the resulting variance in the fill level is small. To determine the distance between the sensor's emitting surface and the catalyst filling in the tube, the last time-of-flight signal that meets the quality requirements during the measurement is used to determine the fill level of the corresponding tube and the corresponding speed of sound. For this purpose, uniform propagation of the sound waves is assumed, and the determined distance is halved in order to consider only one distance and not the outward and return paths.From this distance minus the offset between the radiating surface of the ultrasonic sensor and the opening of the reaction tube, the empty area in the reaction tube is determined; the average filling level is determined from the tube length minus the empty area.

[0076] The speed of sound is temperature dependent. The temperature of the entire measurement setup influences the measurement in that a larger measurement error

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[0078] 12 occurs when the temperature changes. For example, a 3 °C difference in the ambient temperature results in a 1% change in the error. Therefore, continuous temperature measurement is carried out in the vicinity of the reaction tubes using an additional temperature sensor. The measured temperature is used, for example, to adjust the speed of sound for each measurement. This makes it possible to calculate the fill level with high accuracy using the actual speed of sound.

[0079] According to a further embodiment of the method according to the invention, in which the ultrasonic sensor is attached to a measuring carriage, the carriage is moved on a rail system using profiled rollers as guides in a horizontal plane above the openings of the reaction tubes. The relative horizontal position of the ultrasonic sensor to the reaction tube is measured using light barrier sensors. The ultrasonic sensor is aligned so that it is located centrally above an opening of a reaction tube.

[0080] An error-free measurement is only possible if the ultrasonic sensors are located with their emitting surfaces directly above the pipe openings. If this is not the case, correct distance values ​​cannot be determined. To ensure this, two light barriers offset from each other in the direction of travel of the measuring carriage are combined to form a pair for pipe detection. The offset of the light barriers to each other is approximately 5 mm less than the pipe diameter. As long as both light barriers detect the pipe opening at the same time, the distance measurement is triggered and released. To reliably detect the pipe openings, two of these pairs of light barriers can be used simultaneously and connected together to form an OR operation. If one of the pairs of light barriers delivers an ambiguous result, the result of the second pair of light barriers can be used.

[0081] The pairs of light barriers are mounted on the carriage directly in front of the adjacent ultrasonic sensors. They detect the reaction tubes using reflection measurements. When both light barriers of a pair of light barriers detect that the ultrasonic sensors are positioned above the reaction tube, the ultrasonic measurement is initiated. A specific area within the tube is permitted for this purpose. This creates a measurement time window when the measuring carriage advances evenly.

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[0083] 13

[0084] The carriage can be moved manually or automatically. Two different operating modes are available. In manual mode, the carriage is moved slowly over the reaction tubes by hand. In automatic mode, however, the carriage moves independently over the reaction tubes. If the ultrasonic sensor stays above a reaction tube long enough, a measurement can be taken. The measurement is taken when the ultrasonic sensor is above the inner area of ​​the reaction tube. For example, for a reaction tube with a diameter of 20 to 25 mm, a measurement is taken in an area of ​​approximately 8 mm in the center of the reaction tube; measuring closer to the edge could result in unwanted reflections.

[0085] When one of the two pairs of light barriers detects that the ultrasonic sensors are completely above the pipe openings, the level measurement is started. The measurement is repeated as long as the correct positioning above the pipes is maintained. In addition, the measured values ​​are compared with the stored target values, and the result of the level measurement is displayed on the LED bar. As soon as the pair of light barriers detects that the ultrasonic sensors are no longer within the permitted range above the pipe openings, the continuous measurement is stopped and the result is frozen in the LED bar. If a pipe level is detected as being below or above the desired level, or as not measurable (red or yellow LED), a short warning tone also sounds. The result is held until the next row of pipes or the next pipe pattern is detected by the light barriers.

[0086] If the speed is too high, all LEDs on the LED bar are turned off, and an LED on the alignment device indicating excessive speed lights up. No measured values ​​are shown on the display. A long warning tone also sounds. The error message is cleared when the next correct position is reached.

[0087] If the carriage is moved too quickly over the pipes in manual mode, or if the measuring carriage speed is set too high in automatic mode, there won't be enough time to perform a measurement over the pipe openings. The transit time of the ultrasonic signal may then be longer than the time required for the ultrasonic sensors to be correctly positioned over the pipe openings. To prevent this, there is a preset maximum travel speed, which is monitored by the light barriers.

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[0089] 14

[0090] If the measuring carriage is operated automatically, it moves automatically after the measurement is completed to position the ultrasonic sensor over a new reaction tube using the pair of light barrier sensors. In manual operation, the measuring carriage is moved on rails at a slow, constant speed over the tubes to be measured.

[0091] In the event of an error, the measuring carriage moves a short distance further, exposing the incorrectly measured reaction tube or row of reaction tubes. This makes it easier to visually verify, for example, why the measurement could not be performed. The measuring carriage then stops with a warning tone. By briefly pressing the rotary knob, the measurement of the next reaction tube can be continued. The direction of travel is generally freely selectable and can also be determined using the rotary knob.

[0092] According to a further embodiment of the method according to the invention, several ultrasonic sensors are arranged next to each other on the measuring carriage. Ultrasonic measurements are performed simultaneously to determine the fill level of several reaction tubes, with the ultrasonic sensors being activated alternately for the measurement.

[0093] In particular, no adjacent ultrasonic sensors are activated simultaneously. This advantageously reduces crosstalk between adjacent ultrasonic sensors. Crosstalk between adjacent ultrasonic sensors refers to the unwanted detection of ultrasonic signals from the neighboring sensor. This can be caused, for example, by signal reflections from contaminants.

[0094] Because the dwell time of the sensors above the reaction tubes is very short, the ultrasonic sensors cannot be triggered sequentially. For this reason, the adjacent ultrasonic sensors are divided into two groups, which are then triggered alternately. For example, ultrasonic sensors 1, 3, 5, 7, and 9 form one group, while sensors 2, 4, 6, 8, and 10 form the second group. Because no adjacent ultrasonic sensors are used simultaneously, no interference signal can be transmitted from them to a neighboring ultrasonic sensor, and thus, the signal cannot be falsely measured by the adjacent ultrasonic sensor.

[0095] According to a further embodiment of the method according to the invention, a plurality of transit times of emitted

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[0097] 15

[0098] Ultrasonic signals are received and stored, the running times in the evaluation device are compared with a stored, permitted running time interval, those running times that lie outside the permitted running time interval are filtered out and the fill level of the catalyst material is determined from the permitted running times.

[0099] The permissible interval is determined, for example, by the theoretically possible values ​​for the transit time. For an empty pipe, the value would be the maximum transit time, and for a fully filled pipe, the value would be the minimum transit time. The transit time is determined by the speed of sound and the path traveled by the sound. This restriction offers another way to minimize interference signals caused, for example, by crosstalk between two neighboring sensors or by residues in the pipe.

[0100] The invention will now be explained using embodiments with reference to the drawings.

[0101] Figure 1 shows a horizontal cross-section of an embodiment of the arrangement according to the invention,

[0102] Figure 2 shows an embodiment of an ultrasonic sensor used with a matching layer,

[0103] Figure 3 shows schematically the components of the arrangement,

[0104] Figure 4 shows the results of measurements on a reaction tube with clean inner walls,

[0105] Figure 5 shows the results of measurements on a reaction tube with encrusted inner walls,

[0106] Figure 6 shows the results of further measurements on a reaction tube with encrusted inner walls and

[0107] Figure 7 is a flowchart of the method steps of a first embodiment of the method according to the invention.

[0108] M / 62016-PCT With reference to Figures 1 to 6, an embodiment of the arrangement 50 according to the invention is described:

[0109] The arrangement 50 comprises a tube bundle reactor 1. The tube bundle reactor 1 is delimited by a reactor shell, a cylindrical body, with an upper hood and a lower hood at the upper and lower ends of the reactor shell providing a gas-tight seal to the reactor shell. Inside the tube bundle reactor 1, a plurality of vertically arranged reaction tubes 3 are arranged such that the reactor shell encloses the reaction tubes 3. The upper ends of the reaction tubes 3 are each connected in a gas-tight manner to an upper tube plate, and the lower ends of the reaction tubes 3 are each connected in a gas-tight manner to a lower tube plate, i.e., both ends of the reaction tubes 3 are enclosed in the tube plates. The space between the upper hood and the upper tube plate, the space within the reaction tubes 3, and the space between the lower tube plate and the lower hood thus form a gas-tight reaction space.In this reaction chamber, the feed gas mixture is introduced into the tube bundle reactor 1, is subjected to a chemical reaction provided in the tube bundle reactor 1 inside the reaction tubes 3 and is then discharged again from the tube bundle reactor 1.

[0110] The tube bundle reactor 1 has 10,000 to 40,000 reaction tubes 3. Their inner diameter is 25 mm; the total length of the reaction tube 3 is 3,200 mm. The reaction tubes 3 are arranged in a grid, resulting in a recurring linear pattern. One possible grid arrangement is shown in Figure 1, but other recurring linear patterns are also possible. The reaction tubes 3 are cylindrical and open at the top. To operate the tube bundle reactor 1, they are filled with particles of a catalyst material 4. The catalyst particles have a cylindrical shape with a diameter of 5 to 7 mm and a height of 4 to 7 mm. The distance between the opening of the reaction tube 3 and the surface of the particles 4 of the catalyst material is 100 to 700 mm, depending on the fill level.

[0111] To determine the filling level of the reaction tubes 3 with the particles of the catalyst material 4, a sensor device 2 with ultrasonic sensors 6 and an electronics box 5 is located above the reaction tubes 3. The electronics box 5 contains a first control device 26, a second

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[0113] 17

[0114] Control device 27, a calculation unit 28, an alignment device 14, an evaluation device 7, a temperature sensor, and display and operating elements. The ultrasonic sensors 6 are controlled by the first control device 26. They are mounted vertically at the smallest possible distance of less than 30 mm above the openings of the reaction tubes 3, so that they can be moved in a horizontal plane over the openings of the reaction tubes 3. The radiation characteristic of each ultrasonic sensor 6 is an ultrasonic beam. Its vertical axis of symmetry is aligned parallel to a vertical axis of symmetry of a reaction tube 3.

[0115] The ultrasonic sensor 6 has, as shown in Figure 2, an ultrasonic transducer head 17 with an output surface 18 for emitting the ultrasonic signal. Arranged on the output surface 18 is an adaptation layer for adapting the radiation characteristic of the ultrasonic sensor 6 to the geometry of the inner walls of the reaction tubes 3. The thickness of the adaptation layer is greater in the center of the output surface 18 than at the edge. The adaptation layer consists of one or more adhesive films. In Figure 2, the adaptation layer consists of two concentrically applied adhesive films 20, 21 with different diameters. A first adhesive film 20 is tightly attached to the output surface 18 and completely covers it. A second film 21, which is smaller than the first film, is attached to the side of the first film 20 facing away from the output surface 18 in the center of the output surface 18, such that the thickness of the adaptation layer is greater in the center of the output surface 18 than at the edge.The thickness of the first adhesive film 20 is 130 μm and covers the entire coupling-out surface 18. The thickness of the second adhesive film 21 is 130 μm, its diameter is 6.5 mm, and it is centrally attached to the first film 20. Self-adhesive plastic films (Tesaflex® 53948) made of soft PVC and with a thickness of 130 μm are used.

[0116] The disc-shaped foils 20 and 21 are thus arranged concentrically to one another. The ratio of their diameters is approximately 0.26, and the ratio of their areas is approximately 0.07. As shown below, it has been found that a matching layer designed in this way prevents measurement errors due to incrustations or adhesions on the inner walls of the reaction tube 3.

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[0118] 18

[0119] The evaluation device 7 is coupled to the ultrasonic sensors 6 via a data connection 8. Data on the time of transmission and reception of the ultrasonic signal are stored in the evaluation device 7. The transit time is determined, and from this, the fill level is determined. The fill level is the distance from the bottom of the reaction tube 3, on which the particles 4 of the catalyst material rest, to the upper surface formed by the particles 4 of the catalyst material. From the transit time of the ultrasonic signal, the distance from the surface of the ultrasonic transducer head 17 to the surface of the particles 4 of the catalyst material is first calculated, taking into account that the ultrasonic signal travels from the ultrasonic sensor 6 to the surface of the particles 4 and, after reflection, travels back again.Since the distance of the surface of the ultrasonic transducer head 17 above the upper edge of the reaction tube 3 is known and also the distance of this upper edge of the reaction tube 3 to the bottom on which the particles 4 of the catalyst material rest is known, the fill level can be calculated from the travel time of the ultrasonic signal.

[0120] The evaluation device 7 is coupled to a temperature sensor 24, which continuously measures the temperature in the vicinity of the reaction tubes 3. Using the temperature thus determined, the numerical value of the speed of sound is adjusted for the evaluation of the measurement results in the evaluation device 7, based on the known dependence of the speed of sound on temperature.

[0121] An indicator 9, which is placed on the sensor device 2, displays an optical signal that depends on the fill level determined by the evaluation device 7. The desired fill level or an interval of desired fill levels is stored in the evaluation device 7. LEDs indicate whether the fill level is within the specified range. The measurement result is displayed on an LED bar. Three differently colored LEDs are assigned to each measured reaction tube 3. Furthermore, a loudspeaker 10 is provided, which can generate an acoustic signal.

[0122] The arrangement 50 further comprises an alignment device 14. This aligns the ultrasonic sensors 6 in a state ready for measurement. For this purpose, they are attached to a measuring carriage 11, which is mounted on a rail system 12 above the openings

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[0124] 19 of the reaction tubes 3 and is movable in a horizontal plane above the openings of the reaction tubes 3 by means of profiled rollers 13. The movement of the measuring carriage 11 takes place in the "automatic" operating mode with the aid of an electrically driven gear motor and is controlled by a second control device 27. Alternatively, the measuring carriage can also be moved by hand in the "manual" operating mode. For this purpose, the drive unit, which is provided for automatic operation, can be uncoupled. The ultrasonic sensors 6 are arranged next to one another on the measuring carriage 11 such that they correspond to the recurring linear pattern of the grid of the reaction tubes 3.

[0125] When the measuring carriage 11 moves, the ultrasonic sensors 6 thus move over the openings of the reaction tubes 3. After a certain advance of the measuring carriage 11, the vertical axes of the row of ultrasonic sensors 6 coincide with the axes of the reaction tubes 3 below. For example, overlaps of ten reaction tubes 3 with ultrasonic sensors 6 are achieved. The ultrasonic sensors 6 are thus arranged on the measuring carriage 11 in such a way that, by moving the measuring carriage 11 and thus the ultrasonic sensors 6, a row of reaction tubes 3 of the grid is measured by the row of ultrasonic sensors 6 on the measuring carriage 11.

[0126] Felt damping layers are mounted on the underside of the measuring carriage 11 to suppress reflections from neighboring ultrasonic sensors 6. Furthermore, the ultrasonic sensors 6 are controlled so that they do not all emit ultrasonic signals simultaneously, but rather only every other sensor at a time, so that no interference signal is received from the neighboring sensor.

[0127] Light barrier sensors 22 and a calculation unit 28 are located on the alignment device 14. The light barrier sensors 22 consist of two pairs of light barriers. When the sensor device 2 is moved, they detect the relative position of the ultrasonic sensor 6 to the reaction tube 3 in the horizontal plane. For tube detection, two light barrier sensors 22, which are shifted relative to one another in the direction of travel of the measuring carriage 11, are combined into a pair. The offset of the light barrier sensors 22 relative to one another is approximately 5 mm less than the tube diameter of the reaction tube 3. For reliable detection of the tube openings, there are two pairs of these light barriers, which form an OR link.

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[0129] 20 are interconnected. The calculation unit 28 stores how the ultrasonic sensor 6 must be moved by means of the measuring carriage 11 in order to align it so that the vertical axis of the ultrasonic sensor 6 coincides with the vertical axis of the reaction tube 3, so that the ultrasonic transducer head 17 is aligned centrally above the reaction tube 3.

[0130] Furthermore, the travel speed of the measuring carriage 11 is monitored by the light barrier sensors 22. The optical indicator 9 and loudspeaker 10 are also coupled to the measuring carriage 11, so that LEDs and warning signals are activated depending on the behavior of the measuring carriage 11. If the measuring carriage 11 is moved too quickly manually, or if none of the light barrier pairs can detect a correct measuring position during the automatic movement of the measuring carriage 11, a warning tone sounds.

[0131] A rechargeable battery 15 ensures the power supply of the sensor device 2 and the components of the alignment device 14. The battery 15 is connected to the ultrasonic sensors 6 and the light barrier sensors 22 and mounted on the measuring carriage 11.

[0132] To determine the effect of the matching layer, measurements of the arrangement were carried out on a reaction tube 3. The results of these measurements are explained below with reference to Figures 4 to 6:

[0133] During the measurements, the ultrasonic sensor 6 emits an ultrasonic pulse into the reaction tube 3. At the same time, a time measurement is started. The ultrasonic pulse is then reflected by the medium in the tube and subsequently hits the ultrasonic sensor 6 again. At this point in time, the time measurement is stopped and the evaluation device 7, taking into account the recorded ambient temperature and the speed of sound, calculates the propagation time of the ultrasonic pulse and from this the distance of the surface of the ultrasonic transducer head 17 of the ultrasonic sensor 6 from the medium at which the ultrasonic pulse was reflected. From this, the fill level, i.e. the distance from the upper surface formed by the particles 4 of the catalyst material to the ultrasonic transducer head 17, and the fill level height can then be calculated.

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[0135] 21

[0136] In each case, initial measurements were performed using an ultrasonic sensor 6 in which no matching layer was applied to the ultrasonic transducer head 17. Figures 4 to 6 show the signal 29 from these measurements. Furthermore, second measurements were performed in each case, in which the ultrasonic transducer head 17 was provided with the matching layer, i.e., the adhesive films 20 and 21, as described above. This signal 30 from this respective measurement is also shown in Figures 4 to 6.

[0137] Figure 4 shows the results of the measurements on a reaction tube 3 with clean, i.e., smooth, interior walls. The fill level was 707 mm. The signals 29 and 30 shown in Figure 4 show, on the one hand, the transmitted pulse 31 of the ultrasonic sensor 6 and, on the other hand, a received signal 32, which results from the reflection of the ultrasonic pulse by particles 4 of the catalyst material. In the measurements shown in Figure 4, in which the interior walls of the reaction tube 3 were smooth, an accurate and error-free fill level measurement is obtained in both cases.

[0138] However, in practical applications, not under laboratory conditions, but with reaction tubes 3 actually used in a tube-bundle reactor 1, frequent measurement errors occurred, making reliable calculation of the fill level and height impossible. An error analysis showed that the reaction tubes 3, which are used in a tube-bundle reactor 1, have slight incrustations on their inner walls, which already reflect part of the ultrasonic pulse. However, the evaluation device 7 cannot distinguish between the reflections on the inner wall of a reaction tube 3 and those on the particles 4 of the catalyst material.

[0139] To solve the problem of frequent measurement errors, the inner walls of test tubes were coated with various substances in the laboratory to replicate the incrustations found in practice. Further tests were then conducted on these tubes:

[0140] Measurements were again carried out using an ultrasonic sensor 6 in which the ultrasonic transducer head 17 was not provided with a matching layer. The signals 29 of these measurements are shown in Figures 5 and 6. The fill level of the measurements shown in Figure 5 was again 707 mm; the fill level of the measurements shown in Figure 6 was again 207 mm. It was again shown that from these

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[0142] 22

[0143] Signals 29 no reliable calculation of the filling level and the filling level of the particles 4 of the catalyst material was possible.

[0144] Furthermore, measurements were performed with an ultrasonic sensor 6, in which, as explained above, the matching layer, i.e., the two foils 20 and 21, were applied to the ultrasonic transducer head 17. The signals 30 from these measurements are shown in Figures 5 and 6. A significant improvement in signal quality was achieved.

[0145] Comparing signal 29 with signal 30 in Figures 5 and 6, it can be seen that in the measurements with the ultrasonic sensor 6, in which the ultrasonic transducer head 17 is provided with the matching layer, the reflections from the inner walls could be reduced to such an extent that they are no longer detected by the ultrasonic sensor 6. This result was confirmed in further test measurements on the reaction tubes 3 of a tube bundle reactor 1 in use. By applying the matching layer to the ultrasonic transducer head 17, measurement errors that occur due to incrustations or the like on the inner walls of the reaction tube 3 could be eliminated.

[0146] In the following, an embodiment of the method according to the invention for determining the fill level of the particles of a catalyst material 4 in the reaction tubes 3 of a tube bundle reactor 1 by means of the arrangement 50 described above as shown in Figure 7 is described.

[0147] In a first step S1, target values ​​for the runtime measurements as well as a range for permissible fill levels are stored in the evaluation device 7.

[0148] In a second step S2, the ultrasonic sensors 6 are moved over the reaction tubes 3 by means of the second control device 27. The relative horizontal position of the ultrasonic sensors 6 to the reaction tubes 3 is measured using two light barrier sensors 22. As long as both light barrier sensors 22 simultaneously detect the tube openings and the ultrasonic sensors are located within a specified range around the center axis of the tube openings, distance measurements are triggered and enabled by the first control device 26. The pairs of light barrier sensors 22 are directly

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[0150] 23 are mounted in front of the adjacent ultrasonic sensors 6 and detect the reaction tubes 3 via reflection measurements. When both light barrier sensors 22 detect that the ultrasonic sensors 6 are positioned above the reaction tubes 3, the ultrasonic measurement is started. This allows measurements to be taken within a range of approximately 8 mm within the reaction tube 3, which has a diameter of 20 to 25 mm; otherwise, unwanted reflections would occur. Simultaneous ultrasonic measurements are performed to determine the fill level of several reaction tubes 3, with ultrasonic sensors 6 arranged in a row being alternately activated for the measurement. In this case, adjacent ultrasonic sensors 6 are not activated simultaneously; instead, adjacent ultrasonic sensors 6 are triggered alternately.

[0151] In a third step S3, activated ultrasonic sensors 6 transmit an ultrasonic signal from above into the reaction tubes 3 below. At the time of transmission, a signal is sent to the evaluation device 7 in a fourth step S4 to store the start time. The ultrasonic signal reflected in the reaction tube 3 is received by the ultrasonic sensor 6 in a fifth step S5. The received signal is also transmitted to the evaluation device 7 in a sixth step S6. This process is repeated several times within a measurement period for a reaction tube 3. In a seventh step S7, a plurality of travel times of transmitted ultrasonic signals are determined from this. In an eighth step S8, the travel times in the evaluation device 7 are compared with the stored, permitted travel time interval, and those travel times that lie outside the permitted travel time interval are filtered out.From the thus filtered travel times, the fill level of the particles of the catalyst material 4 is calculated using the speed of sound in a ninth step S9, using the last determined permissible value. For this purpose, the last value within the permitted travel time range recorded in a measurement period is used. From the thus determined travel time value, the average distance traveled by the ultrasonic signal is determined using the principle of uniform motion. Since the speed of sound is temperature-dependent, a continuous temperature measurement is also carried out via the additionally installed temperature sensor 24, and the speed of sound used for the calculation is adjusted in the evaluation device 7.

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[0153] 24

[0154] The result for the fill level is compared with stored target values ​​in a tenth step S10. The measured result in mm is shown on a display 25 in an eleventh step S11. The result is also displayed on an LED bar: If the measured value is within the target value interval, a green LED lights up. If a pipe fill level is below or above the desired level, i.e. it does not correspond to the target value range, a red LED lights up. If the process is detected as not measurable, a yellow LED lights up. In the last two cases, a short warning tone also sounds. The result is held until the next measurement of a reaction tube 3 has been taken.

[0155] After the measurement has been completed, the ultrasonic sensors 6 are moved to the next row of reaction tubes 3 by means of the second control device 27 in a twelfth step S12. For this purpose, they are attached to the measuring carriage 11, as described in the exemplary embodiment of the arrangement according to the invention. This carriage moves at a slow, constant speed on the rail system 12 over the reaction tubes 3 to be measured. This occurs automatically by means of a motor. In another exemplary embodiment, the motor drive is uncoupled and the measuring carriage is moved over the reaction tubes 3 by manually pushing or pulling on the rail system 12. The measuring carriage 11 moves continuously, i.e., it continues to move even during the measuring process. The speed of the measuring carriage 11 is continuously measured, and if the speed is too high, a warning signal sounds.

[0156] After the measurement has been completed, the measuring carriage 11 automatically moves on to position the ultrasonic sensors 6 over a new row of reaction tubes 3. Since the positioning of the ultrasonic sensors 6 on the measuring carriage 11 matches the grid of the reaction tubes 3, after a certain advance of the measuring carriage 11, the vertical axes of several ultrasonic transducer heads 17 coincide with the vertical axes of the reaction tubes 3 located below. The fill levels of a further row of reaction tubes 3 can thus be measured. When the reaction tubes 3 are arranged in a triangular arrangement, the measuring carriage 11 can be moved linearly over the reaction tubes 3 in a dog walk. The alignment device 14 ensures that the ultrasonic sensors 6 are moved over the upper openings of the reaction tube 23 and that the measurements are essentially carried out in an area in which the vertical

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[0158] 25

[0159] The axis of symmetry of the ultrasonic beam essentially coincides with the vertical axis of symmetry of a reaction tube 3.

[0160] The alignment device 14, the ultrasonic sensors 6, and the associated evaluation device 7 are supplied with electrical energy via a battery 15. The battery 15 is charged as needed when no measurements are being taken.

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[0162] 26

[0163] List of reference symbols

[0164] 1 tube bundle reactor

[0165] 2 Sensor device

[0166] 3 reaction tubes

[0167] 4 particles of the catalyst material

[0168] 5 Electronics box with control and display elements

[0169] 6 Ultrasonic sensor

[0170] 7 Evaluation device

[0171] 8 Data connection

[0172] 9 Indicator

[0173] 10 speakers

[0174] 11 measuring slides

[0175] 12 rail system

[0176] 13 profile rollers

[0177] 14 Alignment device

[0178] 15 accumulator

[0179] 17 Ultrasonic transducer head

[0180] 18 output surface

[0181] 20 first slide

[0182] 21 second slide

[0183] 22 light barrier sensors

[0184] 24 temperature sensors

[0185] 25 displays

[0186] 26 first control device

[0187] 27 second control device

[0188] 28 Calculation unit

[0189] 29 Signal without matching layer

[0190] 30 Signal with matching layer

[0191] 31 transmission pulse

[0192] 32 Received signal by reflection from particles of the catalyst material

[0193] 33 Received signals through reflections from incrustations

[0194] 50 Arrangement

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Claims

BASF SE 210056W001 27 Patentansprüche 1. Arrangement of a tube bundle reactor (1) and a sensor device (2), wherein the tube bundle reactor (1) comprises a bundle of vertically arranged reaction tubes (3) which are open upwards through upper openings and can be filled with particles of a catalyst material (4), characterized in that the sensor device (2) comprises an ultrasonic sensor (6) and an evaluation device (7), wherein the ultrasonic sensor (6) is configured to emit an ultrasonic signal from above into one of the reaction tubes (3) and to receive the ultrasonic signal reflected in the reaction tube (3), and wherein the evaluation device (7) is coupled to the ultrasonic sensor (6) via a data connection (8) and is configuredto determine the distance of the surface of the particles of the catalyst material (4) picked up by one reaction tube (3) to the ultrasound sensor (6) from the transit time of the received ultrasound signals and from this a fill level of the catalyst material (4) in the reaction tube (3).

2. Arrangement according to claim 1, characterized in that the ultrasonic sensor (6) comprises an ultrasonic transducer head (17) with a coupling surface (18) for emitting the ultrasonic signal and an adaptation layer for adapting the emission characteristic of the ultrasonic sensor (6) to the geometry of the reaction tubes (3) is arranged on the coupling surface (18).

3. Arrangement according to claim 2, characterized in that the thickness of the adaptation layer in the middle of the coupling surface (18) is greater than at the edge.

4. Arrangement according to claim 2 or 3, characterized in that the adaptation layer has a first film (20) which is attached close to the coupling surface (18).

5. Arrangement according to claim 4, characterized in that the adaptation layer has a second film (21) which is smaller than the first film (20) which is attached to the side of the first film (20) facing away from the coupling surface (18) in the middle of the coupling surface (18), so that the thickness of the adaptation layer in the middle of the coupling surface (18) is greater than at the edge. M / 62016-PCT BASF SE 210056W001 28 6. Arrangement according to one of the preceding claims, characterized in that the sensor device (2) has an indicator (9) which is configured to display an optical signal which depends on the determined fill level of the evaluation device (7).

7. Arrangement according to one of the preceding claims, characterized in that the ultrasonic sensor (6) is attached to a measuring slide (11) which is mounted on a rail system (12) above the openings of the reaction tubes (3) and is movable in a horizontal plane above the openings of the reaction tubes (3).

8. Arrangement according to one of the preceding claims, characterized in that the arrangement comprises an alignment device (14) with light barrier sensors (22) configured to detect the relative position of the ultrasonic sensor (6) to the reaction tube (3) in a horizontal plane.

9. Arrangement according to one of the preceding claims, characterized in that the sensor device (2) comprises several ultrasonic sensors (6).

10. Arrangement according to one of the preceding claims, characterized in that the reaction tubes (3) in the tube bundle reactor (1) are arranged in a grid such that a recurring linear pattern results.

11. Arrangement according to claims 9 and 10, characterized in that the ultrasonic sensors are arranged on the measuring slide (11) such that they correspond to the recurring linear pattern of the grid of the reaction tubes.

12. Method for determining the fill level of a catalyst material (4) in the reaction tubes (3) of a tube bundle reactor (1), wherein the tube bundle reactor (1) comprises a bundle of vertically arranged reaction tubes (3) which are opened upwards by upper openings and filled with particles of a catalyst material (4), characterized in that a sensor device (2) comprises an ultrasonic sensor (6) with which an ultrasonic signal is emitted from above into one of the reaction tubes (3) and the ultrasonic signal reflected in the reaction tube (3) is received, M / 62016-PCT BASF SE 210056W001 29 the received signal is transmitted via a data connection (8) to an evaluation unit (7), and the evaluation unit (7) determines the distance of the surface of the particles of the catalyst material (4) taken up by a reaction tube (3) to the ultrasonic sensor (6) from the transit time of the received ultrasonic signals and from this the fill level of the catalyst material (4) in the reaction tube (3).

13. Method according to claim 12, characterized in that the ultrasonic sensor, which is attached to a measuring carriage, is moved on a rail system (12) by means of guide rollers (13) in a horizontal plane above the openings of the reaction tubes (3) and the relative horizontal position of the ultrasonic sensor (6) to the reaction tube (3) is measured by means of light barrier sensors (22) and the ultrasonic sensor (6) is aligned so that the ultrasonic sensor (6) is located centrally above an opening of a reaction tube (3).

14. Method according to claim 13, characterized in that several ultrasonic sensors (6) are arranged next to each other on the measuring carriage (11), and ultrasonic measurements are carried out simultaneously to determine the fill level of several reaction tubes (3), wherein the ultrasonic sensors (6) are activated alternately for the measurement.

15. Method according to claim 12, characterized in that in a measurement period for a reaction tube (3) a plurality of transit times of emitted ultrasonic signals are received and stored, the transit times are compared in the evaluation device (7) with a stored, permitted transit time interval, such transit times which lie outside the permitted transit time interval are filtered out, and the fill level of the catalyst material (4) is determined from the permitted transit times. M / 62016-PCT

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