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

Abstract

The present invention relates to the arrangement of a tube bundle reactor (1) and a sensor device (2), the tube bundle reactor (1) comprising a bundle of vertically arranged reaction tubes (3) which are open at the top through an upper opening and can be filled with particles of a catalyst material (4). The sensor device (2) comprises an ultrasonic sensor (6) and an evaluation device (7), the ultrasonic sensor (6) being designed to emit an ultrasonic signal onto one of the reaction tubes (3) from above and to receive the ultrasonic signal reflected within the reaction tube (3). The evaluation device (7) is coupled to the ultrasonic sensor (6) via a data connection (8) and is designed to determine, from the flight time of the received ultrasonic signal, the distance to the surface of the particles of the catalyst material (4) received by one of the reaction tubes (3) up to the ultrasonic sensor (6) and therefrom to determine the filling level height of the catalyst material (4) in the reaction tube (3).

Description

Technical Field

[0001] The present invention relates to the arrangement of tube bundle reactors and sensor devices. The tube bundle reactor comprises a bundle of vertically arranged reaction tubes, which open at the top through an upper opening and can be filled with particles of catalyst material. Furthermore, the present invention relates to a method for determining the filling level height of the catalyst material in the reaction tubes of a tube bundle reactor by such an arrangement.

Background Art

[0002] The catalyst filling of a tube bundle reactor is a very important step for the performance of the reactor. In addition to other parameters, uniform filling of all reaction tubes is a prerequisite for the optimal yield of the products produced using the reactor.

[0003] A tube bundle reactor filling device is described in German Patent Publication No. 10 2006 013 488 for this purpose, which has a metering chamber that can be filled with a filler material such as a catalyst-coated carrier material, and each tube of the tube bundle reactor can be filled via a supply device adjacent to the metering chamber.

[0004] However, in order to ensure uniform filling, the filling level height of all reaction tubes must be checked very carefully after the catalyst filling process. The filling level height is currently determined by manually inserting a measuring rod into each tube. Since a tube bundle reactor generally has 20,000 to 40,000 tubes, this method is cumbersome and time-consuming and requires a high level of attention and willingness from the personnel involved. In addition, if the measuring rod is placed too hard on the catalyst, there is a risk of damaging the catalyst.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] Accordingly, the present invention is based on the object of providing an arrangement and a method of the type first mentioned, in which the filling level height of the catalyst material particles in the tube bundle reactor is faster, more cost-effective, and less susceptible to the influence of errors.

[0007] This object is achieved according to the invention by an arrangement having the features of claim 1 and by a method having the features of claim 12. Advantageous embodiments and further developments are defined by the dependent claims.

Means for Solving the Problems

[0008] The arrangement according to the invention for the tube bundle reactor described first comprises a sensor device comprising an ultrasonic sensor and an evaluation device. The ultrasonic sensor is designed to emit an ultrasonic signal from above into one of the reaction tubes and receive the ultrasonic signal reflected in the reaction tube. The evaluation device is coupled to the ultrasonic sensor via a data connection and is designed to determine the distance to the surface of the catalyst material particles received by one reaction tube up to the ultrasonic sensor from the flight time of the received ultrasonic signal and therefrom to check the filling level height of the catalyst material in the reaction tube.

[0009] The tube bundle reactor is a chemical reactor in which a particularly strong exothermic reaction, usually an oxidation reaction, takes place in the gas phase. The gas mixture reacts with the aid of a catalyst, optionally in reaction tubes through which a coolant flows.

[0010] In particular, the catalyst material consisting of individual particles is arranged in the reaction tubes. The particles typically have a spherical, solid cylindrical, or hollow cylindrical shape. The ratio of the diameter to the length of the particles is usually in the range of 0.4 to 1.5, and the ratio of the particle diameter to the tube diameter is generally from 1:15 to 1:3. The catalyst usually consists of a mixture of (noble) metals, metal mixed oxides, ceramic substrates such as oxides of silicon, magnesium, aluminum, and titanium, etc. In individual cases, the catalyst consists of only one component. During the operation of the tube bundle reactor, the activity and selectivity of the catalyst material usually decrease over time, and as a result, the catalyst needs to be replaced regularly. For the optimal yield of the reactor, the most perfect synchronization possible of all the reaction tubes of the tube bundle reactor is required. To achieve this synchronization, the quality of the filled catalyst particles must be as constant as possible throughout the filling batch. The quality characteristics here are the intrinsic activity and selectivity of the catalyst compound, the geometric parameters of the catalyst particles such as size and shape or their distribution, and the 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 amount and filling speed during the filling of the reactor must be kept very constant in order to achieve the most uniform filling level height possible. The geometric characteristics, catalyst characteristics, and / or fracture mechanical characteristics are checked or set in upstream tests during the catalyst production, but the homogeneous filling of the reaction tubes must be checked after the filling process, and this arrangement is used for this purpose.

[0011] For this purpose, the ultrasonic sensor is arranged directly above the opening of the reaction tube according to an embodiment of the arrangement according to the invention. The short distance between the emitting surface of the ultrasonic sensor and the opening of the reaction tube is called the offset. In another embodiment of the arrangement according to the invention, the ultrasonic sensor is pushed into the reaction tube.

[0012] The emission characteristics of the ultrasonic sensor are an ultrasonic lobe. The ultrasonic sensor of the arrangement according to the invention is positioned in particular such that the axis of symmetry of the ultrasonic lobe is parallel to the longitudinal axis of the reaction tubes of the tube bundle reactor. Thus, the ultrasonic signal is emitted parallel to the longitudinal axis of the reaction tubes of the tube bundle reactor and into the center of the reaction tubes. In this way, reflections of the ultrasonic signal from the walls of the reactor tubes and protruding contaminants within the reaction tubes are advantageously avoided.

[0013] The flight time of the signal is determined from the emission time and the reception time of the signal. These times are detected by the ultrasonic sensor and stored in the evaluation device respectively. The evaluation device determines the fill level height from the flight time. For this purpose, it is combined with a temperature probe which continuously performs a temperature measurement around the reaction tube in order to ascertain the temperature-dependent speed of sound required for the calculation of the fill level height according to an embodiment of the arrangement according to the invention.

[0014] The fill level height is here understood as the distance from the bottom of the reaction tube on which the particles of the catalyst material are placed to the upper surface formed by the particles of the catalyst material. In contrast, the fill level is understood as the distance to the surface of the particles of the catalyst material from the ultrasonic sensor.

[0015] The arrangement according to the invention has the advantage that the fill level height of the particles of the catalyst material in the tube bundle reactor can be determined more quickly, more cost-effectively and less susceptible to errors with the aid of an ultrasonic sensor. Since the measurement of the fill level height of the filled catalyst particles by means of the ultrasonic sensor is carried out non-contact, in contrast to a measuring rod, damage to the filled catalyst particles due to the measuring process can be prevented. The automatic calculation of the fill level height simplifies and accelerates the measuring method. The working time of the employees required to carry out the measurement can be reduced, and the costs are reduced in that wear of the catalyst material due to damage is minimized. Also, the measurement can be carried out more frequently with less effort so as to ensure an optimized catalyst filling, thereby leading to an improvement in the yield in the reaction process.

[0016] According to one embodiment of the arrangement according to the invention, the ultrasonic sensor comprises an ultrasonic transducer head having a separation surface for emitting ultrasonic signals. An adaptation layer for adapting the emission characteristics of the ultrasonic sensor to the shape of the reaction tube is arranged on the separation surface.

[0017] The problem of unwanted reflections of ultrasonic signals caused by fine deposits on the tube wall can occur during the measurement of the filling level height using an ultrasonic sensor. These destroy the reflected signal by additional echoes. The echoes from the deposits can be reduced by reducing the emission angle.

[0018] For this purpose, for example, commercially available circular planar ultrasonic transducers can be used. These have an ultrasonic transducer head having a separation surface for emitting ultrasonic signals, provided with an adaptation layer. The additional layer causes a change in the emission characteristics of the ultrasonic sensor. The ultrasonic lobe can, for example, have its cross-sectional diameter reduced by the adaptation layer.

[0019] Thus, the emission characteristics of the ultrasonic sensor can advantageously be very easily adapted to the tube shape. By means of the narrow ultrasonic lobe, the signal is emitted only at the center of the tube, reflections at the edges of the tube or at deposits are reduced, and thus disruption of the time-of-flight measurement is prevented.

[0020] According to a further embodiment of the arrangement according to the invention, the thickness of the adaptation layer at the center of the separation surface is greater than at the edge. The thickness of the adaptation layer can also rise abruptly and can be produced by a continuous transition of the layer thickness from the outside of the edge of the bonding surface to the inside of the center. Special changes in the emission characteristics occur depending on the shape of the separation surface.

[0021] The narrow ultrasonic lobe can be produced particularly well by this arrangement and its width can be optimally adapted to the shape of the reactor tube. Thus, reflections at deposits on the wall of the reaction tube can advantageously be avoided even better. The ultrasonic signal propagates only at the center of the tube.

[0022] According to a further embodiment of the arrangement according to the invention, the adaptation layer has a first film tightly fastened to the separation surface. The first film can be, for example, an adhesive film. The use of a film, in particular an adhesive film, ensures that no gap is formed between the ultrasonic transducer head and the adaptation layer. Air entrainment in the gap induces an undesirable change in the ultrasonic signal by material migration and prevents a reliable evaluation of the signal. Furthermore, such adhesive films can be purchased inexpensively and, in various embodiments, for example, with different thicknesses. The mounting of the ultrasonic transducer head is very easy and the size of the layer can be easily adapted as desired.

[0023] According to a further embodiment of the arrangement according to the invention, the adaptation layer has a second film fastened to the surface of the first film facing away from the separation surface at the center of the separation surface, the second film being smaller than the first film and the thickness of the adaptation layer being greater at the center of the separation surface than at the edge.

[0024] The ratio of the diameter of the smaller second film to the diameter of the larger first film is in particular in the range from 0.16 to 0.36, in particular this ratio is 0.26. Thus, the ratio of the area of the smaller second film to the area of the larger first film is in the range from 0.026 to 0.013, preferably 0.07. Measurement errors due to adhesion or skin formation on the inner wall of the reaction tube can be avoided by the adaptation layer designed in this way.

[0025] By using a membrane, in particular two adhesive membranes, no gap occurs between the ultrasonic transducer head, the first membrane, and the second membrane. Thus, the ultrasonic signal is not destroyed by air entrainment between the transfer materials. Furthermore, the two membranes, especially when they are adhesive membranes, can be very easily attached to the transducer head. The materials of the two membranes can be variably selected to optimally match the release characteristics to the existing characteristics of the reaction tube. Different materials and thicknesses can also be selected for the first and second membranes. The radius of the second membrane can also be freely selected. Thus, different ratios of the thickness of the membrane at the center to the thickness of the membrane in the edge region, as well as different ratios of the radii of the first and second membranes can be created.

[0026] Thus, the changed release characteristics of the ultrasonic lobe are very easily and cost - effectively advantageously generated, which is particularly well adapted to the measurement task, in particular the shape of the reaction tube.

[0027] According to a further embodiment of the arrangement according to the invention, the sensor device has an indicator designed to display an optical signal that depends on the confirmed filling level height of the evaluation device.

[0028] The desired filling level height, or the tolerance range of the filling level height, can be pre-stored in the evaluation unit of the sensor device. This target value is compared with the actually measured value of the filling level height after the measurement is completed. Whether the measurement result is within the specified range is output by an optical signal. This can be done, for example, via a bar having light-emitting diodes (LEDs). For this purpose, for example, three different colored LEDs are arranged on the ultrasonic sensor. If the filling level height is within the desired target range, the green LED lights up, and if it is outside the target range, i.e., below or above the selected range, the red LED lights up. Furthermore, if the measured value cannot be confirmed, it can be signaled via yellow light. This applies, for example, if there is a reflection of a contaminant shell that has hindered the evaluation. If the filling level height is too low and / or the power of the ultrasonic signal is too low to be received, it is also signaled by yellow light. If the filling level height is excessively high, the reflected signal cannot be reliably evaluated either. This range is also called the "dead zone". Since the reflected signal also reaches the ultrasonic sensor very quickly here, it is still in the dead time even after the signal is emitted. In this case too, the yellow LED is displayed. In addition, the result of the filling level height can be output in millimeters via a display on the ultrasonic sensor.

[0029] This arrangement advantageously enables the rapid identification of any errors in the filling level height or the measurement. The result of each measurement is displayed until the next measurement is started. Thus, sufficient time is left to check the measurement and optionally stop the measurement process for filling correction or restarting the measurement.

[0030] In one embodiment of the arrangement according to the invention, the sensor device alternatively or additionally has components for generating an acoustic signal, which are designed to generate an acoustic signal. If the filling level height is identified as being below or above the desired value or being unmeasurable, and thus the red or yellow LED is displayed, a short warning tone additionally sounds, for example via a loudspeaker. This enables an easier and automated check of the filling level.

[0031] According to a further embodiment of the arrangement according to the invention, the ultrasonic sensor is fastened to a measuring carriage which is attached to a rail system above the opening of the reaction tube and is movable in a horizontal plane above the opening of the reaction tube. The measuring carriage is moved, in particular for more accurate guidance, on profile rollers. The carriage can move continuously. Thus, in particular, it is not stopped when measurements are taken using the ultrasonic sensor.

[0032] When the ultrasonic sensor is located in the central region above the reaction tube during the continuous movement of the measuring carriage, the measurement is started. In particular, a speed monitoring unit is installed on the measuring carriage. Due to the small pipe diameter, the carriage cannot move too fast, so that sufficient time remains for the measurement. The measuring carriage can be moved manually or automatically on the rail system. In the case of an overly fast manual movement of the measuring carriage, or if the exact measuring position cannot be assumed during the automatic travel of the measuring carriage, a warning tone sounds.

[0033] The measurement carriage has the advantage that the ultrasonic sensor is aligned on the measurement carriage where it coincides with the reaction tube. Therefore, it is not necessary to re-establish accurate alignment for each individual measurement. This is particularly important because in the case of inaccurate alignment of the sensor, the ultrasonic waves can be reflected by the tube jacket or the dirt deposits sitting thereon, and the measurement may not be carried out accurately. Therefore, the measurement is less affected by errors as a whole for the measurement carriage. Due to the alignment or continuous advancement on the rail system, the measurement period is very efficient over time.

[0034] According to a further embodiment of the arrangement according to the invention, the sensor device comprises a rechargeable battery designed to guarantee the voltage supply of the sensor device. A voltage supply module for supplying power to both the voltage supply module of the measurement carriage and the ultrasonic sensor is attached to the measurement carriage. This makes it possible for the arrangement to function without a direct connection to the power grid. The battery can be charged when it is not necessary to currently carry out the measurement of the filling level height.

[0035] According to a further embodiment of the arrangement according to the invention, the arrangement comprises an alignment device having an optical barrier sensor designed to detect the relative position of the ultrasonic sensor with respect to the reaction tube in the horizontal plane.

[0036] The alignment device can comprise a calculation unit in addition to the optical barrier sensor. When the sensor device is displaced, the optical barrier sensor detects the relative position of the ultrasonic sensor with respect to the reaction tube. The calculation unit calculates therefrom how the ultrasonic sensor has to be moved by the measurement carriage in order to align the vertical axis of the ultrasonic transducer head with the longitudinal axis of the reaction tube.

[0037] For the detection of the reaction tubes, in particular two specific light barriers which are offset from each other in the direction of movement are combined to form a pair. The offset of the light barriers with respect to each other is approximately 5 mm smaller than the tube diameter. As long as both light barriers detect the tube opening simultaneously, the distance measurement is triggered and activated. There are two of these pairs of light barriers which are interconnected to form an OR connection for reliable detection of the tube opening.

[0038] The pair of light barriers advantageously enables the automatic start of the measurement of the filling level height, i.e., precisely when the ultrasonic sensor is arranged directly above the permitted inner region of the reaction tube. Thus, the use of the pair of light barriers increases the degree of automation of the measurement again and reduces its sensitivity to errors.

[0039] According to a further embodiment of the arrangement according to the invention, the sensor device comprises a plurality of ultrasonic sensors.

[0040] The installation of the measuring carriage, the computing unit, and the alignment device having the pair of light barriers enables the measurement to be highly automated, so that it is possible to simultaneously measure the filling level heights of a plurality of reaction tubes. For example, a plurality of ultrasonic sensors arranged in a row are arranged on the measuring carriage. As described above, an LED and a display for displaying the filling level height are assigned to each ultrasonic sensor. This is particularly advantageous since a tube bundle reactor has thousands of reaction tubes arranged therein, and the measurement of their filling level heights can be completed significantly faster by performing the measurements of a plurality of reaction tubes simultaneously.

[0041] According to a further embodiment of the arrangement according to the invention, the reaction tubes are arranged in the tube bundle reactor with a uniform grid or a uniform tube spacing such that a repeating linear pattern is obtained.

[0042] The grid is understood as a regular pattern distributed on the surface. The grid is formed by repeating the displacement of this pattern in the horizontal plane. Therefore, the reaction tube is arranged in the horizontal plane such that the same pattern is shown multiple times in at least one direction during the horizontal movement over the tube opening.

[0043] The structured sequence of the selection of the reaction tube during the measurement process can advantageously be easily found in this way.

[0044] According to a further embodiment of the arrangement according to the invention, the ultrasonic sensors are arranged on the measurement carriage so as to correspond to the repeated linear pattern of the grid of reaction tubes. Therefore, during the movement of the measurement carriage in the direction of the repeated pattern, the ultrasonic sensors move above the openings of the reaction tubes, and after a specific advancement of the measurement carriage, the vertical axes of these ultrasonic sensors are aligned on the measurement carriage such that they always coincide with the longitudinal axis of the reaction tube. This relative arrangement between the grid of reaction tubes and the ultrasonic sensors on the measurement carriage enables a linear movement of the measurement carriage without continuous displacement of the ultrasonic sensors on the measurement carriage for individual measurements. Furthermore, by the repeated displacement of the measurement carriage, all reaction tubes can be measured.

[0045] A plurality of ultrasonic sensors can be arranged on the measurement carriage, and they all experience the same advancement by advancing the measurement carriage, and thus can move above the reaction tubes simultaneously. For example, the ultrasonic sensors are arranged adjacent to each other at equal distances in a row. This arrangement is reflected in the reaction tubes. Also, they are arranged continuously in rows. Therefore, by the uniform advancement of the measurement carriage, it is moved over the reaction tubes and measured row by row. Therefore, a plurality of reaction tubes can be advantageously measured simultaneously, and only the linear advancement of the measurement carriage is required for this purpose, and no additional alignment of the individual ultrasonic sensors is necessary. Therefore, this arrangement results in an accelerated measurement method that is less affected by errors.

[0046] In a further embodiment of the arrangement according to the invention, in the region of the ultrasonic sensor below the measuring carriage, for example by means of an adhesive tape, a non-woven material or felt is provided, whereby the acoustic signals of adjacent ultrasonic sensors are attenuated. These attenuation layers made of non-woven material or felt are attached to the measuring carriage so as to suppress unwanted reflections from other ultrasonic sensors.

[0047] The invention further relates to a method for determining the filling level height of a catalyst material in a reaction tube of a tube bundle reactor using a sensor device comprising an ultrasonic sensor, using which an ultrasonic signal is emitted from above into one of the reaction tubes, the ultrasonic signal reflected in the reaction tube is received, the received signal is transmitted to an evaluation device via a data connection, and the evaluation device determines from the flight time of the received ultrasonic signal the distance from the surface of the particles of the catalyst material received by the reaction tube to the ultrasonic sensor and therefrom the filling level height of the catalyst material in the reaction tube.

[0048] The method according to the invention can in particular be carried out by means of the arrangement according to the invention. This has the same advantages as the arrangement according to the invention.

[0049] As soon as an ultrasonic signal is emitted in the method according to the invention, the start time of the emission is transmitted to the evaluation device. The arrival time of the reflected signal at the ultrasonic sensor is also transmitted to the evaluation device. Subsequently, a distance measurement is carried out indirectly via a flight time measurement of the ultrasonic signal.

[0050] During the measurement of the filling level height of the reaction tube, a plurality of ultrasonic pulses are emitted into the reaction tube. The power of the ultrasonic sensor for emitting the ultrasonic pulses is selected such that even in an empty tube, a sufficiently large reflected signal can be detected and thus the maximum penetration of the signal can be detected.

[0051] Due to the shape of the catalyst material particles, variations in the filling level height occur at different positions within the reaction tube in the order of the sizes of the catalyst material particles. Since this variation is small in terms of the particle size and the resulting variation in the filling level height, it is not considered in the measurement. To determine the distance from the emission surface of the sensor to the catalyst filling inside the tube, the last flight time signal that meets the quality requirements in the measurement is used to determine the corresponding filling level height of the tube and the corresponding speed of sound. Uniform propagation of the sound wave is assumed for this purpose, and the confirmed distance is halved in order to consider only one distance instead of the round-trip. The free space of the reaction tube is confirmed from this distance minus the offset between the emission surface of the ultrasonic sensor and the opening of the reaction tube, and the average filling level height is obtained from the tube length minus the free space.

[0052] The speed of sound depends on temperature. The temperature of the complete measurement setup affects the measurement as long as a larger measurement error occurs when the temperature changes. For example, when there is a difference of 3 °C ambiently, a 1% change in error occurs. Therefore, in particular, continuous temperature measurement is performed around the reaction tube via an additionally installed temperature probe. The speed of sound is adapted to the measurement temperature, for example, for each measurement. In this way, it is possible to calculate the filling height with high accuracy using the actual speed of sound.

[0053] According to a further embodiment of the method according to the invention, in which the ultrasonic sensor is fastened on the measurement carriage, this is moved on a rail system by profile rollers as guides within a horizontal plane above the opening of the reaction tube, and the relative horizontal position of the ultrasonic sensor with respect to the reaction tube is measured by an optical barrier sensor. The ultrasonic sensor is here aligned such that the ultrasonic sensor is centered above the opening of the reaction tube.

[0054] Measurement without error can only be performed when the ultrasonic sensor is arranged such that its emission surface is directly above the tube opening. Otherwise, an accurate distance value cannot be confirmed. To verify this, two light barriers shifted relative to each other in the moving direction of the measurement carriage are combined to form a pair for tube detection. The offset of the light barriers relative to each other is approximately 5 mm smaller than the tube diameter. As long as both light barriers detect the tube opening simultaneously, the distance measurement is triggered and activated. To ensure detection of the tube opening, two of these pairs of light barriers interconnected to form an OR connection can be used simultaneously. If one of the pairs of light barriers yields an ambiguous result, the result of the second pair of light barriers can be used.

[0055] The pairs of light barriers are attached to the carriage immediately in front of the ultrasonic sensors arranged adjacent to each other. They detect the reaction tube via reflection measurement. When both light barriers of the pair of light barriers detect that the ultrasonic sensor is arranged above the reaction tube, the ultrasonic measurement is started. For this purpose, a specific area within the tube is allowed. This results in a measurement time window with the uniform forward movement of the measurement carriage.

[0056] The movement of the carriage can be performed manually or automatically. For this purpose, two different operating modes are available. In the manual operation, the carriage is slowly moved by hand above the reaction tube. In contrast, in the automatic operation, the carriage moves independently above the reaction tube. Measurement can be performed when the ultrasonic sensor is arranged above the reaction tube for a sufficiently long time. The measurement is performed when the ultrasonic sensor is located above the inner region of the reaction tube. For example, in the case of a reaction tube with a straight diameter of 20 to 25 mm, the measurement is performed within an area of approximately 8 mm from the center of the reaction tube. If the measurement is performed closer to the edge, unwanted reflections may occur.

[0057] When the ultrasonic sensor is located exactly above the tube opening and one of the two light barrier pairs detects it, the filling level measurement is started. The measurement is repeated as long as correct positioning above the tube is provided. In addition, the measured value is compared with the stored target value, and the result of the filling level height is displayed on the LED bar. As soon as the light barrier pair detects that the ultrasonic sensor is no longer located within the allowable area above the tube opening, the continuous measurement is stopped and the result freezes within the LED bar. If the tube filling level is detected as being below or above the desired level, or as being unmeasurable (red or yellow LED), a short warning tone sounds additionally. The result is held until the next tube row or the next tube pattern is detected by the light barrier.

[0058] At excessive speed, especially when all the LEDs of the LED bar are turned off and an LED for indicating that the speed has been exceeded lights up on the alignment device. The measured value is not displayed on the display. In addition, a long warning tone sounds. The error display is canceled again at the next correct position.

[0059] If the carriage is moved too fast above the tube in manual operation, or if an excessive speed of the measurement carriage is set in automatic operation, there will not be enough time left to perform the measurement above the tube opening. Then, the flight time of the ultrasonic signal may be longer than the period during which the ultrasonic sensor is accurately positioned above the tube opening. To prevent this case, there is a specified maximum moving speed monitored by the light barrier.

[0060] When the measurement carriage is operated automatically, it continues to move automatically after the measurement is completed in order to position the ultrasonic sensor by the light barrier sensor pair above the new reaction tube. During manual operation, the measurement carriage moves at a slow constant speed on the rail above the tube to be measured.

[0061] In case of an error, the measurement carriage continues to move a short distance so that the measured reaction tube or the row of reaction tubes is exposed to the rough space. Thus, for example, the reason why the measurement could not be performed can be visually checked. Thereafter, the measurement carriage stops together with a warning sound. By operating the rotary knob for a short time, it is possible to continue the measurement of the next reaction tube. The moving direction can in principle be freely selected and can also be determined individually via the rotary knob.

[0062] According to a further embodiment of the method according to the invention, a plurality of ultrasonic sensors are arranged adjacent to each other on the measurement carriage. The ultrasonic measurements for determining the filling level heights of the plurality of reaction tubes are carried out simultaneously, and the ultrasonic sensors are activated alternately for the measurement.

[0063] In particular, adjacent ultrasonic sensors are not activated simultaneously. In this way, crosstalk between adjacent ultrasonic sensors can be advantageously reduced. Crosstalk between adjacent ultrasonic sensors is understood as an undesirable detection of the ultrasonic signals of adjacent sensors. This can be induced, for example, by reflection of the signal on contaminants.

[0064] Since the residence time of the sensor above the reaction tube is very short, the ultrasonic sensor cannot be triggered continuously. 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, 9 form one group, and sensors 2, 4, 6, 8, 10 form a second group. Since adjacent ultrasonic sensors are not used simultaneously, no interference signal from there to the adjacent ultrasonic sensors is generated, and thus it cannot be erroneously measured by the adjacent ultrasonic sensors.

[0065] According to a further embodiment of the method according to the invention, during the measurement period of the reaction tube, a plurality of flight times of the emitted ultrasonic signals are received and stored, the flight times are compared with the tolerated flight time intervals stored in the evaluation device, the flight times deviating from the tolerated flight time intervals are excluded, and the filling level height of the catalyst material is determined from the tolerated flight times.

[0066] The tolerated intervals result, for example, from the theoretically possible values of the flight times. Thus, using an empty tube, the value of the maximum flight time is predicted, and using a completely filled tube, the minimum flight time is predicted. The flight time is obtained from the speed of sound and the distance covered by the sound. This limitation offers further possibilities, for example, to minimize interference signals caused by crosstalk between two adjacent sensors or by residues in the tube.

[0067] Hereinafter, the present invention will be described based on exemplary embodiments with reference to the drawings.

Brief Description of the Drawings

[0068]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiments for Carrying Out the Invention

[0069] An exemplary embodiment of arrangement 50 according to the present invention will be described with reference to FIGS. 1 to 6. Arrangement 50 comprises a tube bundle reactor 1. The tube bundle reactor 1 is defined by a reactor casing, a cylindrical body, and an upper hood and a lower hood hermetically close the reactor casing at the upper and lower ends of the reactor casing. A plurality of vertically arranged reaction tubes 3 are arranged inside the tube bundle reactor 1 such that the reactor casing surrounds the reaction tubes 3. The upper ends of the reaction tubes 3 are each hermetically connected to an upper tube base, and the lower ends of the reaction tubes 3 are each hermetically connected to a lower tube base, that is, both ends of the reaction tubes 3 are enclosed within the tube bases. Thus, the space between the upper hood and the upper tube base, the space inside the reaction tubes 3, and the space between the lower tube base and the lower hood form an airtight reaction chamber. A feed gas mixture is introduced into the tube bundle reactor 1 of this reaction chamber, undergoes the intended chemical reaction in the tube bundle reactor 1 inside the reaction tubes 3, and is then discharged again from the tube bundle reactor 1.

[0070] The tube bundle reactor 1 has from 10,000 to 40,000 reaction tubes 3. Their inner diameter is 25 mm, and the total length of the reaction tubes 3 is 3200 mm. The reaction tubes 3 are arranged in a grid pattern such that a repeating linear pattern occurs. One possible grid arrangement is shown in FIG. 1. However, other repeating linear patterns are also possible. The reaction tubes 3 are cylindrical and open at the top. For the operation of the tube bundle reactor 1, these are filled with particles 4 of a catalyst material. 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 of the openings of the reaction tubes 3 from the surface of the particles 4 of the catalyst material is 100 to 700 mm depending on the filling level.

[0071] To determine the filling level height of the reaction tube 3 by the particles 4 of the catalyst material, a sensor device 2 having an ultrasonic sensor 6 and an electronic device box 5 is arranged above the reaction tube 3. The electronic device box 5 houses a first control device 26, a second control device 27, a calculation unit 28, an alignment device 14, an evaluation device 7, a temperature probe, and display and operation elements. The ultrasonic sensor 6 is operated via the first control device 26. These are vertically fastened at the minimum possible distance of less than 30 mm above the opening of the reaction tube 3 so that they can move in the horizontal plane above the opening of the reaction tube 3. The emission characteristics of each ultrasonic sensor 6 are ultrasonic lobes. Its vertical axis of symmetry is aligned parallel to the vertical axis of symmetry of the reaction tube 3 in each case.

[0072] As shown in FIG. 2, the ultrasonic sensor 6 has an ultrasonic transducer head 17 having a separation surface 18 for emitting ultrasonic signals. An adaptation layer for adapting the emission characteristics of the ultrasonic sensor 6 to the shape of the inner wall of the reaction tube 3 is arranged on the separation surface 18. The thickness of the adaptation layer is greater at the center of the separation surface 18 than at the edge. The adaptation layer consists of one or more adhesive films. In FIG. 2, the adaptation layer consists of two concentrically attached adhesive films 20, 21 having different diameters. The first adhesive film 20 is tightly fastened to the separation surface 18 and completely covers it. The second film 21, which is smaller than the first film, is fastened to the surface of the first film 20 facing away from the separation surface 18 at the center of the separation surface 18 so that the thickness of the adaptation layer is greater at the center of the separation surface 18 than at the edge. The thickness of the first adhesive film 20 is 130 μm, which covers the entire separation surface 18, and the thickness of the second adhesive film 21 is 130 μm and its diameter is 6.5 mm, which is fastened to the center of the first adhesive film 20. A self-adhesive plastic film (Tesaflex® 53948) made of soft PVC and having a thickness of 130 μm is used.

[0073] Thus, the disk-shaped membranes 20 and 21 are arranged concentrically with respect to each other. The ratio of these diameters is approximately 0.26, and the ratio of these areas is approximately 0.07. As shown below, the conforming layer formed in this way has been shown to have the result that no measurement error occurs due to the formation of the outer skin or adhesion on the inner wall of the reaction tube 3 during the measurement in the reaction tube 3.

[0074] The evaluation device 7 is coupled to the ultrasonic sensor 6 via a data connection 8. The data in the country of emission and reception of the ultrasonic signal is stored in the evaluation device 7. The time of flight is determined, and from that the filling level height is confirmed. The filling level height is the distance from the base of the reaction tube 3 on which the particles 4 of the catalyst material are placed to the upper surface formed by the particles 4 of the catalyst material. First, the distance from the surface of the ultrasonic transducer head 17 to the surface of the particles 4 of the catalyst material is calculated from the time of flight of the ultrasonic signal, taking into account that the ultrasonic signal travels from the ultrasonic sensor 6 to the surface of the particles 4 and then returns after reflection. Since the distance of the surface of the ultrasonic transducer head 17 above the upper edge of the reaction tube 3 is known, and in addition, the distance of this upper edge of the reaction tube 3 to the base on which the particles 4 of the catalyst material are placed is also known, the filling level height can be calculated from the time of flight of the ultrasonic signal.

[0075] The evaluation device 7 is coupled to a temperature probe 24, which continuously measures the temperature around the reaction tube 3. Using the temperature thus confirmed, the numerical value of the speed of sound is adapted via the known dependence of the speed of sound on temperature for the evaluation of the measurement results in the evaluation device 7.

[0076] The indicator 9 arranged on the sensor device 2 displays an optical signal depending on the confirmed filling level height of the evaluation device 7. The desired filling level height, or the interval of the desired filling level height, is stored in the evaluation device 7. Whether the filling level height is within the specified range is output by an LED. The result of the measurement is displayed on an LED bar. Three different colored LEDs are assigned to each measured reaction tube 3. A loudspeaker 10 capable of generating an acoustic signal is further provided.

[0077] The arrangement 50 further comprises an alignment device 14. This aligns the ultrasonic sensors 6 into a measurement-ready state. For this purpose, these sensors are attached to a rail system 12 above the reaction tube 3 and fastened to a measurement carriage 11 which is movable in a horizontal plane above the opening of the reaction tube 3 by means of profile rollers 13. The movement of the measurement carriage 11 is effected in the operating mode "automatic" with the aid of an electric drive geared motor and is controlled by a second control device 27. Alternatively, the measurement carriage can also be moved manually in the operating mode "manual". The drive unit provided for the automatic operation can be separated for this purpose. The ultrasonic sensors 6 are arranged adjacent to one another on the measurement carriage 11 so as to correspond to the repetitive linear pattern of the grid of the reaction tube 3.

[0078] Thus, during the movement of the measurement carriage 11, the ultrasonic sensors 6 move above the opening of the reaction tube 3. After a specific advance of the measurement carriage 11, the vertical axis of the row of ultrasonic sensors 6 coincides with the axis of the underlying reaction tube 3. For example, an overlap of 10 reaction tubes 3 and ultrasonic sensors 6 is achieved. Thus, the ultrasonic sensors 6 are arranged on the measurement carriage 11 such that, due to the displacement of the measurement carriage 11 and thus of the ultrasonic sensors 6, one row of reaction tubes 3 of the grid is measured by the row of ultrasonic sensors 6 on the measurement carriage 11.

[0079] A damping layer made of felt is attached under the measurement carriage 11 so that the reflections of adjacent ultrasonic sensors 6 are suppressed. Furthermore, the ultrasonic sensors 6 are operated such that not all of them emit ultrasonic signals at the same time but rather only every other sensor always emits an ultrasonic signal and no interference signals are received from adjacent sensors.

[0080] The optical barrier sensor 22 and the calculation unit 28 are arranged on the alignment device 14. The optical barrier sensor 22 consists of two pairs of optical barriers. During the displacement of the sensor device 2, they detect the relative position of the ultrasonic sensor 6 with respect to the reaction tube 3 in the horizontal plane. Two optical barrier sensors 22 shifted relative to each other in the moving direction of the measuring carriage 11 are combined to form a pair for tube detection. The offset of the optical barrier sensors 22 relative to each other is approximately 5 mm smaller than the tube diameter of the reaction tube 3. For reliable detection of the tube opening, two of these pairs of optical barriers are interconnected to form an OR connection. The calculation unit 28 stores how the ultrasonic sensor 6 must be moved by the measuring carriage 11 so that the vertical axis of the ultrasonic sensor 6 coincides with the vertical axis of the reaction tube 3, with the ultrasonic transducer head 17 arranged centrally above the reaction tube 3.

[0081] Furthermore, the moving speed of the measuring carriage 11 is monitored by the optical barrier sensor 22. The optical indicator 9 and the loudspeaker 10 are also coupled to the measuring carriage 11 so that the LED and the warning signal are activated according to the behavior of the measuring carriage 11. In the case of an excessively fast manual movement of the measuring carriage 11, or if neither of the pairs of optical barriers can detect the exact measuring position during the automatic travel of the measuring carriage 11, a warning sound will sound.

[0082] The rechargeable battery 15 ensures the voltage supply of the components of the sensor device 2 and the alignment device 14. The battery 15 is connected to the ultrasonic sensor 6 and the optical barrier sensor 22 and is installed on the measuring carriage 11.

[0083] To confirm the effect of the conforming layer, measurements were performed on the reaction tube 3. Referring to FIGS. 4 to 6, the results of these measurements are described below. During measurement, the ultrasonic sensor 6 emits ultrasonic pulses into the reaction tube 3. Time measurement starts simultaneously. Subsequently, the ultrasonic pulses are reflected by the medium arranged in the tube and then impinge on the ultrasonic sensor 6 again. At this time, the time measurement is stopped, and the evaluation device 7 calculates the flight time of the ultrasonic pulses taking into account the detected ambient temperature and the speed of sound, and from that, calculates the distance of the surface of the ultrasonic transducer head 17 of the ultrasonic sensor 6 from the medium from which the ultrasonic pulses were reflected. Subsequently, the filling level, i.e., the distance to the upper surface formed by the particles 4 of the catalyst material up to the ultrasonic transducer head 17, and the filling level height can be calculated therefrom.

[0084] In each case where no matching layer is applied to the ultrasonic transducer head 17, a first measurement was performed using the ultrasonic sensor 6. The signals 29 of these measurements are shown in FIGS. 4 to 6. Furthermore, in each case where a matching layer, i.e., adhesive films 20 and 21, is provided on the ultrasonic transducer head 17 as described above, a second measurement was performed. This signal 30 of each of these measurements is also shown in FIGS. 4 to 6.

[0085] FIG. 4 shows the measurement results in a reaction tube 3 having a clean, i.e., smooth, inner wall. The filling level was 707 mm. The signals 29 and 30 shown in FIG. 4 show, on the one hand, the emitted pulse 31 of the ultrasonic sensor 6 and, on the other hand, the received signal 32 resulting from the reflection of the ultrasonic pulse from the particles 4 of the catalyst material. In the measurement shown in FIG. 4 where the inner wall of the reaction tube 3 is smooth, in each case an accurate and error-free measurement of the filling level is obtained.

[0086] However, in practical applications using the reaction tubes 3 actually used in the tube bundle reactor 1 rather than under laboratory conditions, frequent measurement errors occurred, making it impossible to accurately calculate the filling level height and filling level. Error analysis showed that the reaction tubes 3 used in the tube bundle reactor 1 had a slight skin formation on the inner wall, which was already reflecting part of the ultrasonic pulse. However, the evaluation device 7 was unable to distinguish between the reflection from the inner wall of the reaction tube 3 and the reflection from the particles 4 of the catalyst material.

[0087] To solve the problem of frequent measurement errors, in order to simulate the skin formation based on experience, the inner walls of test tubes were coated with various substances in the laboratory. Subsequently, further experiments were conducted on these tubes. Further experiments were carried out using an ultrasonic sensor 6 without an adaptation layer provided on the ultrasonic transducer head 17. The signals 29 of these measurements are shown in FIGS. 5 and 6. The filling level of the measurement shown in FIG. 5 was again 707 mm, and the filling level of the measurement shown in FIG. 6 was again 207 mm. From these signals 29, it was again shown that it was impossible to accurately calculate the filling level height and filling level of the particles 4 of the catalyst material.

[0088] Furthermore, as described above, measurements were taken using an ultrasonic sensor 6 to which an adaptation layer, namely two membranes 20 and 21, was applied to the ultrasonic transducer head 17. The signals 30 of these measurements are shown in FIGS. 5 and 6. A clear improvement in signal quality was achieved.

[0089] When comparing the signal 29 in FIGS. 5 and 6 with the signal 30, in the measurement using the ultrasonic sensor 6 provided with the matching layer on the ultrasonic transducer head 17, it is shown that the reflections from the inner wall can be sufficiently reduced and thus they are no longer detected by the ultrasonic sensor 6. This result was confirmed by further test measurements on the reaction tubes 3 of the tube bundle reactor 1 during use. By applying the matching layer to the ultrasonic transducer head 17, it was possible to prevent measurement errors caused by, for example, the formation of a skin on the inner wall of the reaction tube 3.

[0090] An exemplary embodiment of the method according to the invention for determining the filling level height of the catalyst material particles 4 in the reaction tubes 3 of the tube bundle reactor 1 by means of the above-described arrangement 50, as shown in FIG. 7, is described below.

[0091] In a first step S1, a target value for the time-of-flight measurement and a range of acceptable filling level heights are stored in the evaluation device 7.

[0092] In the second step S2, the ultrasonic sensor 6 is moved by the second control device 27 above the reaction tube 3. The relative horizontal position of the ultrasonic sensor 6 with respect to the reaction tube 3 is measured here using two light barrier sensors 22. As long as both light barrier sensors 22 detect the tube opening simultaneously and the ultrasonic sensor is located within a defined area around the central axis of the tube opening, the distance measurement is triggered and enabled by the first control device 26. The pair of light barrier sensors 22 is attached to the measurement carriage 11 directly in front of the ultrasonic sensors 6 arranged adjacent to each other and detects the reaction tube 3 via reflection measurement. When both light barrier sensors 22 detect that the ultrasonic sensor 6 is arranged above the reaction tube 3, the ultrasonic measurement is started. Thus, it is possible to measure within the reaction tube 3 having a direct line of 20 to 25 mm in a range of approximately 8 mm; otherwise, undesirable reflections occur. Ultrasonic measurements for determining the filling level height of a plurality of reaction tubes 3 are performed simultaneously, and the ultrasonic sensors 6 arranged in a row are activated alternately for measurement. In this case, adjacent ultrasonic sensors 6 are not activated simultaneously, and adjacent ultrasonic sensors 6 arranged adjacent to each other are triggered alternately.

[0093] In the third step S3, the activated ultrasonic sensor 6 emits an ultrasonic signal into the reaction tube 3 arranged from above downwards. At the emission time, in the fourth step S4, the signal is transmitted to the evaluation device 7 to store the start time. The ultrasonic signal reflected in the reaction tube 3 is received by the ultrasonic sensor 6 in the fifth step S5. The received signal is also transmitted to the evaluation device 7 in the sixth step S6. This procedure is repeated multiple times during the measurement period of the reaction tube 3. In the seventh step S7, a plurality of flight times of the emitted ultrasonic signals are determined therefrom. In the eighth step S8, the flight times are compared with the allowable flight time intervals stored in the evaluation device 7, and these flight times outside the allowable flight time intervals are excluded. In the ninth step S9, the filling level height of the particles 4 of the catalyst material is calculated with the aid of the speed of sound from the flight times thus excluded using the last confirmed allowable value. For this purpose, the last value located within the allowable flight time range recorded during the measurement period is used. The average distance covered by the ultrasonic signal is determined from the flight time values thus confirmed via the principle of uniform movement. Since the speed of sound depends on temperature, temperature measurement is also continuously performed via an additionally installed temperature probe 24 and the speed of sound used in the calculation is adapted within the evaluation device 7.

[0094] The result of the filling level height is compared with the stored target value in the tenth step S10. The measurement result in millimeters is displayed on the display 25 in the eleventh step S11. In addition, the result is displayed on the LED bar. If the measured value is within the target value interval, the green LED lights up. Thus, if the tube filling level height is below or above the desired level, thus the tube filling level height does not correspond to the target value range, the red LED lights up. If the procedure is identified as not measurable, the yellow LED lights up. In the last two cases, a short warning sound additionally sounds. The result is held until the next measurement of the reaction tube 3 is made.

[0095] After the measurement is completed, the ultrasonic sensor 6 is moved by the second control device 27 to the reaction tubes 3 in the next row in the twelfth step S12. For this purpose, these sensors are fastened to the measurement 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 above the reaction tubes 3 to be measured. This is done automatically by a motor. In another exemplary embodiment, the motor drive is disengaged and the measurement carriage is moved by manually pushing or pulling it on the rail system 12 above the reaction tubes 3. The measurement carriage 11 moves continuously. Thus, it continues to move also during the measurement procedure. In this case, the speed of the measurement carriage 11 is continuously measured and a warning signal is given if it is too fast.

[0096] After the measurement is completed, the measurement carriage 11 continues to move automatically in order to position the ultrasonic sensor 6 above the reaction tubes 3 in the new row. Since the positioning of the ultrasonic sensor 6 on the measurement carriage 11 coincides with the grid of the reaction tubes 3, after a specific forward movement of the measurement carriage 11, the vertical axis of the ultrasonic transducer head 17 coincides with the vertical axis of the underlying reaction tube 3. Thus, the filling level height of the reaction tubes 3 in a further row can be measured. The measurement carriage 11 can move slowly linearly above the reaction tubes 3 in an arrangement with reaction tubes 3 at triangular intervals. The alignment device 14 ensures here in any case that the ultrasonic sensor 6 moves above the upper opening of the reaction tube 23 and that the measurement is essentially carried out in a region where the vertical symmetry axis of the ultrasonic lobe coincides essentially with the vertical symmetry axis of the reaction tube 3 in any case.

[0097] The alignment device 14, the ultrasonic sensor 6, and the associated evaluation device 7 are supplied with electrical energy via the storage battery 15. The storage battery 15 is charged as needed immediately when no measurement is currently being carried out.

Explanation of reference numerals

[0098] 1 Tube bundle reactor 2 Sensor device 3 Reaction tube 4 Catalyst material particles 5 Electronic device box with operation and display elements 6 Ultrasonic sensor 7 Evaluation device 8 Data connection 9 Indicator 10 Loudspeaker 11 Measuring carriage 12 Rail system 13 Profile roller 14 Alignment device 15 Storage battery 17 Ultrasonic transducer head 18 Separation surface 20 First film 21 Second film 22 Light barrier sensor 24 Temperature probe 25 Display 26 First control device 27 Second control device 28 Calculation unit 29 Signal without matching layer 30 Signal with matching layer 31 Emission pulse 32 Received signal due to reflection of catalyst material particles 33 Received signal due to reflection of sheath formation 50 Arrangement

Claims

1. 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), the reaction tubes (3) opening at the top through an upper opening and being fillable with particles of a catalyst material (4), the sensor device (2) comprises an ultrasonic sensor (6) and an evaluation device (7), the ultrasonic sensor (6) is designed to emit an ultrasonic signal from above to one of the reaction tubes (3) and to receive the ultrasonic signal reflected within the reaction tube (3), the evaluation device (7) is coupled to the ultrasonic sensor (6) via a data connection (8) and is designed to determine, from the flight time of the received ultrasonic signal, the distance to the surface of the particles of the catalyst material (4) received by the one reaction tube (3) up to the ultrasonic sensor (6) and therefrom to determine the filling level height of the catalyst material (4) within the reaction tube (3), arrangement.

2. The ultrasonic sensor (6) comprises an ultrasonic transducer head (17) having a separating surface (18) for emitting the ultrasonic signal, and an adaptation layer is arranged on the separating surface (18) in order to adapt the emission characteristics of the ultrasonic sensor (6) to the shape of the reaction tube (3). The arrangement according to claim 1.

3. The thickness of the adaptation layer is greater at the center of the separating surface (18) than at the edges. The arrangement according to claim 2.

4. The adaptation layer has a first membrane (20) tightly fastened to the separating surface (18). The arrangement according to claim 2 or 3.

5. The adaptation layer is smaller than the first membrane (20) and has a second membrane (21) fastened to the surface of the first membrane (20) facing away from the separating surface (18) at the center of the separating surface (18) such that the thickness of the adaptation layer is greater at the center of the separating surface (18) than at the edges. The arrangement according to claim 4.

6. The sensor device (2) has an indicator (9) designed to display an optical signal depending on the determined filling level height of the evaluation device (7). The arrangement according to any one of claims 1 to 5.

7. The ultrasonic sensor (6) is fastened to a measurement carriage (11) which is attached to a rail system (12) above the opening of the reaction tube (3) and is movable in a horizontal plane above the opening of the reaction tube (3), the arrangement according to any one of claims 1 to 6.

8. The arrangement comprises an alignment device (14) having an optical barrier sensor (22) designed to detect the relative position of the ultrasonic sensor (6) with respect to the reaction tube (3) in a horizontal plane, the arrangement according to any one of claims 1 to 7.

9. The sensor device (2) comprises a plurality of ultrasonic sensors (6), the arrangement according to any one of claims 1 to 8.

10. The reaction tube (3) is arranged in a grid pattern within the tube bundle reactor (1) such that a repeating linear pattern is obtained, the arrangement according to any one of claims 1 to 9.

11. The ultrasonic sensor is arranged on the measurement carriage (11) so as to correspond to the repeating linear pattern of the grid of the reaction tube, the arrangement according to claim 10 when dependent on claim 9.

12. A method for determining the filling level height of a catalyst material (4) within a reaction tube (3) of a tube bundle reactor (1), wherein the tube bundle reactor (1) comprises a bundle of the reaction tubes (3) arranged vertically, the reaction tubes (3) being open at the top through an upper opening and fillable with particles of the catalyst material (4), a sensor device (2) comprises an ultrasonic sensor (6), using which an ultrasonic signal is emitted from above into one of the reaction tubes (3), and the ultrasonic signal reflected within the reaction tube (3) is received, the received signal is transmitted to an evaluation device (7) via a data connection (8), and the evaluation device (7) determines, from the flight time of the received ultrasonic signal, the distance to the surface of the particles of the catalyst material (4) received by the reaction tube (3) up to the ultrasonic sensor (6) and therefrom determines the filling level height of the catalyst material (4) within the reaction tube (3), method.

13. The ultrasonic sensor fastened on the measurement carriage is moved on the rail system (12) by a guide roller (13) within a horizontal plane above the opening of the reaction tube (3), and the relative horizontal position of the ultrasonic sensor (6) with respect to the reaction tube (3) is measured by an optical barrier sensor (22), and the ultrasonic sensor (6) is aligned such that the ultrasonic sensor (6) is centered above the opening of the reaction tube (3). The method according to claim 12.

14. A plurality of ultrasonic sensors (6) are arranged adjacent to each other on the measurement carriage (11), and ultrasonic measurements for determining the filling level heights of a plurality of reaction tubes (3) are carried out simultaneously, and the ultrasonic sensors (6) are activated alternately for the measurements. The method according to claim 13.

15. A plurality of flight times of the emitted ultrasonic signals are received and stored during the measurement period of the reaction tube (3), the flight times are compared with an allowable flight time interval stored in the evaluation device (7), the flight times deviating from the allowable flight time interval are excluded, and the filling level height of the catalyst material (4) is confirmed from the allowable flight times. The method according to claim 12.

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