DK2443346T3 - Pumps and luminaires with sensors. - Google Patents

Description

PUMPS AND FITTINGS HAVING SENSORS Description

The invention concerns a component for flow-conducting systems, wherein a fluid within the flow-conducting system is influenced by the component, and the component is formed as a power-generating and/or working machine or as a valve with a shut-off element, and a sensor is placed in the component. The invention furthermore concerns a method for detecting deposits on the walls of such components.

Such components find application in flow-conducting systems as pumps, turbines and/or valves. Here pumps are designed as units with variously coupled drive motors, as compact motor pump units, or as other known models.

The components are integrated into flow-conducting systems. These can take the form of piping systems of larger plants, such as chemical or biotechnological production plants, or power plants.

The fluids can be present in liquid or gaseous form, wherein the liquids or gases can also be populated with solid particles. The invention is preferably used in liquids, wherein the application of the invention is particularly suitable for aqueous solutions.

The component can influence the fluid in various ways. In the case of a centrifugal pump, for example, energy can be supplied from the component to the fluid. Here the fluid is firstly accelerated by the impeller of the pump. The kinetic energy supplied is then converted into pressure energy. The fluid can also be influenced by the component in terms of its volumetric flow rate or its flow velocity. This happens, for example, when the component is embodied as a valve. By varying the position of the shut-off element of the valve, the flow cross-section through which the fluid must pass is altered. By this means the volumetric flow rate can be regulated.

Such components are often provided with sensors, which determine states or specific material properties of the fluid. Thus pumps can be equipped with a pressure sensor. Sensors are also used in valves. In DE 197 25 376 Al, for example, a branch-regulating valve for the adjustment of volumetric flow rates is described. For purposes of detecting the volumetric flow rate, a sensor is integrated into a flow housing. The sensor communicates with an evaluation unit.

The flow of fluids through pumps or valves can lead to the formation of deposits, which in many cases can represent a serious economic and technical problem. For example, bacteria can form in deposits, which lead to a deterioration of product quality. Furthermore, deposits can also have an influence on the flow characteristics. In addition, there is an increase in pressure loss. In the case of small flow cross-sections blockages can even occur. Damage to the material can also be caused by deposits.

The deposits can take the form of either inorganic or organic substances.

Important examples of inorganic deposits are carbonates, oxides or hydroxides, which precipitate as scale, rust or ochre on the walls of the component.

The most important organic deposits are biofilms. In the field of hygiene technology, for example in the production of food and pharmaceuticals or in biotechnology, these can lead to considerable problems. Growth is caused by biomass, and impurities that are trapped in the biomass. Bacteria, fungi, yeasts, diatoms and protozoa are just a few of the organisms that cause the build-up of biomass. If the bio-deposition caused by these organisms is not controlled, it interferes with process operations and adversely affects product quality. In the production of food and pharmaceutical products strict purity levels must be maintained, since contamination with bacteria, or metabolic products of microorganisms can cause damage to the health of the consumer.

The components on which deposits form can be made of various materials, such as stainless steel, grey cast iron, ceramic or plastic. Here the surface structure influences the formation of deposits, wherein macroscopically rough surfaces in general offer surfaces that are more vulnerable to attack than smooth surfaces.

The flow velocity also influences the formation of deposits. Thus bio-deposits are preferably produced in regions with a slow flow. US 2008/0163700 A1 discloses a sensor system for a pipeline in which a transmitter and a receiver are positioned spatially apart on the pipeline. The arrangement serves to determine flow rate and provide pipeline monitoring using the ultrasonic Doppler method. US 2007/0006656 A1 discloses a system and method for the monitoring of deposits in the pipelines of a heating system. The sensors used send acoustic signals into the pipeline. JP 61 091509 A shows another method for measuring the thickness of deposits in a pipeline by means of the ultrasonic Doppler method.

The object of the present invention is to provide a component with a sensor which influences a fluid located within a flow-conducting system and at the same time records and quantitatively evaluates the formation of the deposits. Another object of the invention is to develop a method for the detection of deposits on the walls of such components.

This object is achieved in that the sensor comprises at least one transmitter and at least one receiver, wherein the transmitter generates acoustic waves on the surface of the sensor, and the receiver detects these surface waves generated by the transmitter, and the sensor generates signals for an evaluation unit, which determines the level of deposit formation in the component by means of a comparison with reference data.

The surface of the sensor preferably consists of a piezoelectric substrate on which comb electrodes are applied as transmitter and receiver. A comb electrode forms a first interdigital transducer (IDT), the so-called transmitter-interdigital transducer (transmitter IDT), which generates a surface wave on the piezoelectric substrate. The second comb electrode forms a second interdigital transducer, the so-called receiver-interdigital transducer (receiver-IDT). After passing through a certain measuring section, the surface waves generated by the transmitter are detected by the receiver.

The substrate can consist of any piezoelectric that is suitable for the excitation of waves. By the application of a high-frequency alternating voltage to the transmitter IDT, electroacoustic waves are excited by virtue of the piezoelectricity of the substrate. A wave excited by the transmitter IDT travels along the surface of the substrate and generates in the receiver IDT a high-frequency alternating voltage that is electronically evaluated.

The formation of a deposit on the surface of the sensor affects the propagation velocity of the waves. The level of deposit formation can be determined in various ways. For example, conclusions can be drawn regarding the level of deposit formation from the phase and/or amplitude displacement of the waves. Here the phase shift is determined in measurements with a fixed frequency.

The system has a natural frequency that depends on the deposited mass. This shifts as the deposited mass alters, wherein the shift in frequency is recorded. The shift of the resonance frequency thus also allows conclusions to be drawn about the deposited mass on the sensor surface.

The more the deposit formation progresses, the greater is the difference from the deposit-free surface. What is decisive for a determination of the level of deposit formation is a comparison of the measured data with reference data. As a rule, data for a deposit-free sensor surface are used as a reference. In the case of the reference measurement, the process conditions preferably correspond to the conditions that also exist when carrying out the measurement of the deposit formation.

The sensor is preferably designed as a compact unit. It has proved to be beneficial to provide a wall of the component with a bore into which the sensor is precisely inserted. In some cases, it proves to be particularly advantageous if the sensor is inserted flush with the flow-conducting wall of the component. In this manner it can be integrated into pumps or valves without disturbing the flow characteristics of the component. In this case, the flow is tangential to the sensor. This arrangement is particularly suitable for deposits that preferably form at high flow velocities.

It can also be advantageous to arrange the sensor such that it is recessed with respect to the flow-conducting wall of the component. This creates a cavity in front of the sensor in which the fluid flows more slowly. A vortex flow is formed in the cavity, which causes the flow to move across the sensor surface at different angles. These factors can promote the formation of deposits, in particular the formation of bio-deposits. In such an arrangement, the sensor is located at a point of the component that is prone to deposit formation. In this manner, the formation of deposits in the component can be detected early, and appropriate countermeasures can be initiated.

The level of deposit formation can be specified, for example, as the mass of the deposit layer that is forming on the sensor. As the formation of deposits progresses, the height of the deposit layer also increases. It is also conceivable for the structure of the deposit to alter as the formation of the deposit layer progresses and becomes increasingly more compact. In this case, the density of the deposit layer as a physical quantity would be a measure for the level of deposit formation.

The sensor generates signals and forwards the latter to an evaluation unit. The evaluation unit detects the signals of the sensor and by way of an algorithm determines the level of deposit formation. The signals that the sensor forwards to the evaluation unit enter into the algorithm as measurement signals. With the aid of reference data the algorithm establishes a correlation between the sensor data and the level of deposit formation.

The evaluation unit can also be integrated into the sensor, for example in the form of a processor.

In a particularly advantageous variant of the invention, a signal is emitted by the evaluation unit when a limiting value that corresponds to a certain level of deposit formation is exceeded. It proves to be particularly advantageous if this signal leads to the triggering of a process that causes the walls to be cleaned. The processing of the sensor signal and/or the triggering of the cleaning process can be carried out by means of a process control system.

By using the inventive component, the production cycle can be operated for as long a time as possible and the cleaning cycle can be operated for as short a time as necessary, without causing a deterioration of the product quality. The operators of the production facilities no longer have to rely on experiential values, but have reliable measurement data that are continuously recorded. The cleaning process is initiated when a certain level of deposit formation has been exceeded. This prevents the cleaning process from being initiated either too late or too early. On the one hand, this protects the product quality from being negatively affected by a deposit formation that is too far advanced. On the other hand, production time is prevented from being lost.

During the cleaning process, the deposit is continuously reduced by the use of cleaning agents. Here, during the cleaning process, the deposited mass remaining is continuously recorded. The cleaning process is carried out until the deposit is completely removed, or falls below a predetermined limiting value. Subsequently, the cleaning agent is flushed out of the process with a flushing fluid, for example a flushing liquid. The inventive component prevents the cleaning process or the flushing process from being carried out for an unnecessarily long time. Thus, any squandering of detergent, flushing fluid and production time is avoided. Conversely, it is ensured that the cleaning process is terminated only when the pipes are to a large extent free of deposit. This ensures a high product quality.

Changes in the physical boundary conditions at the sensor surface, such as changes in the viscosity or temperature of the fluid, affect the propagation velocity of the surface waves. Therefore, it is also possible with the inventive component to record the type of fluid flowing past the sensor. Thus, it can be determined with the sensor, for example, whether a fluid, a cleaning agent or a flushing fluid that is necessary for the production process is flowing through the component.

After the triggering of the cleaning process, a cleaning agent is added to the process, which reaches the sensor only after a certain dead time. The dead time is greater the longer the flow paths that must be travelled from the point of introduction of the cleaning agent to the sensor. Since the sensor can detect a change in the type of fluid flowing past its surface, the inventive method can be used to determine the time at which the cleaning agent arrives at the sensor.

After the end of the cleaning process, the component is flushed, wherein the cleaning agent is removed from the component. Only after a certain dead time is the cleaning agent present in the lines once again completely flushed out of the component. After the flushing process, the fluids necessary for the production process are resupplied. With the sensor the point in time can be detected at which the flushing fluid has been completely removed from the component. This avoids any contamination of the product by residual amounts of flushing fluid. A particular advantage of the invention is that the sensor can be used not only for determining the formation of deposits in the component, but at the same time for determining the viscosity or the temperature of the fluid. The propagation velocity of the surface waves depends on the viscosity and the temperature of the fluid. In accordance with the invention, the component therefore takes the form of one that combines several measurement methods in an integrated manner.

In a particularly advantageous embodiment of the invention, the component contains at least one further sensor. This sensor determines state variables of the fluid that can affect the deposit measurements. In particular, the viscosity or temperature of the fluid can affect the measurements of the level of deposit formation. Here various measuring methods can be used by the additional sensors. For example, they may take the form of a temperature-dependent resistor or a thermocouple. The additional sensors also forward their signals to the evaluation unit. The evaluation unit calculates influences on the measurements of the level of deposit formation as a result of fluctuations within the state variables of the fluid. By means of a data comparison, the first sensor can thus be calibrated with respect to the deposit measurement. In this way, cross-sensitivities that occur as a result of variations in the viscosity and/or the temperature of the fluid can be excluded.

Further features and advantages of the invention ensue from the description of examples of embodiment, with reference to figures, and from the figures themselves. Here:

Fig. 1: shows a centrifugal pump with a deposit sensor,

Fig. 2: shows an enlargement of the sensor surface,

Fig. 3: shows a valve with a recessed deposit sensor,

Fig. 4: is a diagram showing the changeovers between the production, cleaning and flushing cycles.

In Fig. 1 is shown a component 1 for flow-conducting systems, wherein a fluid located within the fluid-conducting system is affected by the component 1. In the example of embodiment, the component 1 is designed as a centrifugal pump. The fluid is advanced by means of an impeller 10, which is mounted on a drive shaft 11. The fluid enters the pump 1 through the suction nozzle 12 arranged on the axis of rotation, and is accelerated by the rotating impeller 10. By the action of the centrifugal force, the fluid flows radially outwards from the axis of rotation into a volute 13, and from there via the discharge port 14 into a pipeline of the flowconducting system. The flow-conducting system can be, for example, a pipeline system in which the component 1 is installed. A sensor 3 is integrated into a wall 2 of the component 1. The surface 4 of the sensor 3 is in contact with the fluid. On the side of the sensor 3 facing away from the fluid is fixed a means of connection 5, via which the sensor 3 communicates with an evaluation unit 6. The means of connection 5 can be designed as plug-in, screw, or an otherwise conventional means of connection for the production of electrical connections. Via the means of connection 5 the sensor data are forwarded to the evaluation unit 6. The power supply to the sensor 3 can also take place via the means of connection 5. The surface 4 of the sensor 3 protrudes into the pressure side cavity of the impeller of the component 1. The sensor 3 detects deposits that form on its surface 4.

Fig. 2 shows the surface 4 of the sensor 3. At least part of the surface 4 of the sensor 3 is designed in the form of a piezoelectric substrate 7. A transmitter 8 and a receiver 9 are arranged on the piezoelectric substrate 7. These take the form of two comb electrodes designed as interdigital transducers. An oscillator set to a fixed frequency generates an alternating electrical signal with a constant amplitude. Here it has proved to be advantageous if the oscillator is part of the sensor 3 and is arranged in the sensor body. By way of the transmitter 8, a surface wave is generated in the piezoelectric material 7. After passing through a measuring section the acoustic signal is converted by way of the receiver 9 into an alternating current electrical signal. Deposit formation leads to an alteration in the propagation velocity and the amplitude of the surface wave. The resulting alteration in phase of the signal compared with the deposit-free measurement is recorded by the evaluation unit 6.

Another inventive component 1 is shown in Fig. 3. The component 1 takes the form of a valve, which affects a fluid located within a flow-conducting system. The flow rate of the fluid can be regulated by the component 1. With the aid of an actuator 15, here embodied as a hand wheel, a shut-off element is moved. By virtue of the alteration in position of the shut-off element, the flow cross-section in the component 1 is altered. The component 1 can take the form of, for example, a valve, a slide, a tap or a flap. The component 1 is part of a flow-conducting system. This can take the form of, for example, a piping system of a larger plant, such as a chemical production plant, a biotechnological production plant, or a power plant. With the component 1, the fluid located within the flow-conducting system is affected, in that the volumetric flow rate or the flow velocity can be varied. The sensor 3 is integrated into a wall 2 of the component 1. Here the flow-conducting wall 2 has a build-up of material 16 on its external face. An opening 17 is introduced into the build-up of material 16. In the opening 17, the sensor 3 is arranged recessed so as to form an interior cavity 18. The interior cavity 18 is located within the build-up of material 16. In the example of embodiment, the opening 17 is designed as a simple bore within the build-up of material 16. By virtue of the recessed arrangement of the sensor surface 4 a secondary vortex forms within the interior cavity 18. This secondary vortex has a lower flow velocity than the main flow. The vortex flow impinges onto the sensor surface 4 at a variety of angles. As a result of the decelerated flow and the vertical impact, the formation of bio-deposits on the surface 4 of the sensor 3 is enhanced. The surface 4 of the sensor 3 consists at least partially of a piezoelectric substrate 7. A transmitter 8 and a receiver 9 are arranged on the piezoelectric substrate 7. At an output of the sensor 3 a means of connection 5 is connected, which communicates with an evaluation unit 6. The means of communication 5 can be designed as a plug-in, screw, or an otherwise conventional means of connection for producing electrical connections. As an alternative to a fixed means of connection, the signals can be transmitted by radio. The evaluation unit 6 can be supplied from an external power source and/or have an integrated power source. This can take the form of accumulators, batteries, power supplies, thermoelectric generators, solar cells, or the like. The sensor 3 detects deposits on its surface 4 in the manner already described.

Fig. 4 shows a diagram in which the mass deposited on the sensor surface 4 and the concentrations of production, cleaning and flushing fluid are plotted as functions of time. The production process starts at time to. At the sensor 3, the fluid, for example a liquid, flows past with a constant product concentration. The product concentration is shown as a solid line 19. For purposes of representing the product concentration, the line 19 is made thinner than the line 20, which represents the deposited mass. From a time ti, a deposit begins to build up on the sensor surface 4. At time t2, when a certain limiting value of deposited mass, marked on the left-hand ordinate a with value "1", is exceeded, a cleaning fluid, for example a cleaning liquid, is introduced into the process. The cleaning fluid only reaches the sensor 3 at the time t3. The time period t3 -12 is the dead time that the cleaning fluid requires to get from its point of introduction to the sensor 3. From the time t3, the concentration of cleaning fluid at the sensor 3 increases. The concentration of cleaning fluid is shown as a dashed line 21. At the same time, the concentration of production fluid decreases. The deposited mass initially increases further and reaches its maximum at time U. From then onwards the deposited mass is reduced.

From time ts onwards the production fluid is completely displaced by the cleaning fluid. The cleaning fluid has reached its maximum concentration. The deposited mass continues to decrease until time te. From the time te a flushing fluid is fed into the process. The concentration of the flushing fluid is shown as line 22, which consists of a sequence of one dash and two dots. The flushing fluid only reaches the sensor 3 at the time tj. The time period ti-te is a dead time, which the flushing fluid requires in order to travel from its point of introduction to the sensor 3. From the point in time tj, the concentration of flushing fluid at the sensor 3 increases. At the same time, the concentration of cleaning fluid decreases. At the time ts, the concentration of flushing fluid has reached its maximum, while the cleaning fluid has been completely displaced. In order to ensure that no cleaning fluid is left in the process, the flushing operation continues even after the cleaning fluid has dropped to a zero concentration, thus providing a temporal safety margin. The process is then switched back to production fluid. After a certain dead time, the production fluid reaches the sensor 3 at time t9. The concentration of production fluid increases until time tio, while the concentration of flushing fluid decreases. From the point in time tio onwards, at the sensor 3 the flushing fluid is completely displaced by the production fluid. According to the above-described operation, the sensor 3 detects the deposited mass on its surface 4. As already stated, the sensor 3 can continue to detect whether production, cleaning or flushing fluid is flowing past it.

Claims (19)

A component (1) for flow-carrying systems in which a fluid located within the flow-carrying system is actuated by the component (1) and the component (1) is designed as a power and / or working machine or as a luminaire with a locking element, wherein the component (1) comprises a sensor (3), characterized in that the sensor (3) is located in the component (1) and comprises at least one transmitter (8) and at least one receiver (9), the transmitter (8) producing acoustic waves on the surface (4) of the sensor (3) and the receiver (9) record the surface waves produced by the transmitter, and the sensor (3) generates signals to an analyzing unit (6) which, by means of a comparison with the reference data, calculates the degree of a coating formation in the component (1). Component according to claim 1, characterized in that the transmitter (8) and the receiver (9) are designed as camel electrodes designed as an interdigital transducer. Component according to claim 1 or 2, characterized in that at least part of the surface (4) consists of a piezoelectric substrate (7). Component according to claim 3, characterized in that transmitter (8) and receiver (9) are positioned on the piezoelectric substrate (7). Component according to one of claims 1 to 4, characterized in that the analyzer (6) calculates the degree of coating formation from a frequency shift and / or from a phase shift and / or from an amplitude shift. Component according to one of claims 1 to 5, characterized in that the sensor (3) is integrated into a wall (2) of the component (1). Component according to one of claims 1 to 5, characterized in that the sensor (3) is located on a wall (2) of the component (1). Component according to one of claims 1 to 7, characterized in that the analyzing unit (6), when exceeding a limit value corresponding to a certain degree of coating formation, emits a signal. Component according to claim 8, characterized in that the signal triggers a process which causes a cleaning of the fluid-wetted inner wall of the component (υιό). Component according to one of claims 1 to 9, characterized in that the component (1) contains at least one additional sensor which determines at least one state size of the fluid and transmits its data to the analyzer (6), where the analyzer (6) calculates the influence on the measurements. of the degree of coating formation from fluctuations within the state sizes of the fluid. A method for detecting coatings on walls of a component (1) for live systems where a fluid located within the flow system is actuated by the component (1) and the component (1) is designed as a power and / or working machine or as a luminaire with a locking element, characterized in that a sensor (3) is located in the component (1), the sensor (3) comprising at least one transmitter (8) and at least one receiver (9), the transmitter (8) ) produces acoustic waves on the surface (4) of the sensor (3), and the receiver (9) records these surface waves generated by the transmitter, and the sensor generates signals to an analyzing unit (6) which, by means of a comparison with the reference data, calculates the degree of a coating formation in the component (1). Method according to claim 11, characterized in that the transmitter (8) and the receiver (9) are designed as camel electrodes designed as an interdigital transducer. Method according to claim 11 or 12, characterized in that the surface (4) of the sensor (3) consists of a piezoelectric substrate (7). Method according to one of claims 11 to 13, characterized in that the analyzer (6) calculates the degree of coating formation from a frequency shift and / or from a phase shift and / or from an amplitude shift. Method according to one of claims 11 to 14, characterized in that the sensor (3) is integrated into a wall (2) of the component (1). Method according to one of claims 11 to 14, characterized in that the sensor (3) is located on a wall (2) of the component (1). Method according to one of claims 11 to 16, characterized in that the analyzing unit (6), when exceeding a limit value corresponding to a certain degree of coating formation, gives a signal. Method according to claim 17, characterized in that the signal triggers a process which causes a cleaning of the fluid-wetted internal wall of the component (1). Method according to one of claims 11 to 18, characterized in that the component (1) contains at least one additional sensor which determines at least one state size of the fluid, and transmits its data to the analyzer (6), where the analyzer (6) calculates influences on the measurements of the degree of coating formation from fluctuations within the state sizes of the fluid.