Computer-implemented method for detecting and/or determining an anomaly in a centrifugal pump

The present application is based upon and claims the right of priority to BE Patent Application No. 2024/5267, filed May 6, 2024, the disclosure of which is hereby incorporated by reference herein in its entirety for all purposes.

The invention relates to a computer-implemented method for detecting and/or determining an anomaly in a centrifugal pump, including the steps: in a normal state, accelerating and/or decelerating a rotor of the centrifugal pump for quantifying at least one term of a dynamic rotor model of the centrifugal pump, and in a fault state differing from the normal state, accelerating and/or decelerating the rotor of the centrifugal pump for detecting at least one fault parameter.

Centrifugal pumps are known from the prior art and are used to convey a liquid by means of a rotary movement of an impeller. The liquid to be conveyed enters a pump chamber of the centrifugal pump through a suction opening, is captured by the rotating impeller and subsequently conveyed into a pressure outlet. Any solids contained in the liquid can settle in the region of the impeller and on the inside of a pump housing and thus negatively affect the hydraulic and/or mechanical efficiency of the centrifugal pump or even cause the centrifugal pump to become blocked and fail.

Although several methods for detecting and/or determining an anomaly and in particular for unblocking centrifugal pumps are known from the prior art, current practice indicates that the known methods are not ideal for safely and reliably protecting a centrifugal pump from damage, due to possibly not detecting the blockage early enough, and in particular for reliably detecting and/or determining a corresponding anomaly in the centrifugal pump.

On the basis of this situation, an objective of the present invention is to provide a method for detecting and/or determining an anomaly in a centrifugal pump which can detect and classify the anomaly, and in particular a blockage, more reliably and more quickly than the solutions known from the prior art, and/or can initiate targeted measures for eliminating the anomaly, in particular to clear the blockage.

The objective of the invention is achieved by the features of the independent claim. Advantageous embodiments are specified in the subclaims.

Accordingly, the objective is achieved by a computer-implemented method for detecting, determining and/or classifying an anomaly in a centrifugal pump, including the steps:

An essential aspect of the proposed solution is that a digital twin of the centrifugal pump is created by the dynamic rotor model, whereby a parameter estimation is carried out by solving the inverse problem, for example by solving an optimization problem, in order to thus be able to determine the anomaly, in particular a blockage situation of the centrifugal pump, using the identified parameters. The anomaly may be, for example, bearing damage including wear and/or ageing, seal damage including wear and/or ageing, a particularly large change in temperature, a consequence such as expansion and/or a change in viscosity, an incorrect alignment of pump components, a consequence such as misalignments and/or changes in gap sizes, a blockage inside the centrifugal pump, in particular at different points, a corrosion effect, a deposit effect, multi-component fluids in the impeller, multiphase or cavitating fluids in the impeller, an unknown increase in friction, etc. The dynamic rotor model determined in this way makes it much easier to detect or determine an anomaly more accurately. In other words, the proposed method makes it much easier to analyze a blockage situation or another possible type of mechanical malfunction relating to the rotation of the rotor of the centrifugal pump. In the event of a blockage as an anomaly, an unblocking routine suitable for the blockage situation can be selected in order to return the centrifugal pump to its normal state as quickly as possible.

In summary, the method provides a mathematical and/or physical analysis of an acceleration or deceleration phase of a motor, in particular including the shaft and all rotating components of the centrifugal pump, in comparison with a previously determined digital twin of the centrifugal pump for the purpose of identifying potential blockage situations and/or further resistance or resistance-related torques and forces. Based on such a classification of the blockage situation, for example with regard to the location of a blockage in the interior of a pump housing of the centrifugal pump, a problem-oriented unblocking routine suitable for the blockage can be selected. The method thus enables a faster and more efficient unblocking sequence for sewage or waste water pumps.

The proposed method can preferably be used to determine a blockage. In particular, the terms of the dynamic rotor model can be determined during a coordinated, preferably stepwise run-up sequence and/or run-down sequence. To detect the at least one fault parameter, the method takes into account in particular a breakaway and/or static frictional torque, a frictional torque directly proportional to the angle of rotation, in particular as stiffness, any number of frictional torques directly proportional to angular velocities with different exponents, in particular as damping of different orders, and/or allows the selection of a cleaning sequence which is optimally suited to the anomaly depending on the classification of the current blockage. The proposed method also allows the detection of a dry run, the detection of a total blockage in particular, and differentiation with regard to both directions of rotation of the rotor and/or pre-processing of raw time signals such as torque, angular velocity and/or angle of rotation, such as the smoothing and/or filtering of the signals for example.

The term ‘computer-implemented’ is defined to mean in particular that the proposed method can be or is executed by a computer, a computer-based control unit, a microprocessor, cloud-based or the like. Preferably, all steps of the method are carried out by the computer, i.e. computer-implemented. In particular, the normal state is defined as the state of the centrifugal pump in which the centrifugal pump delivers a fluid without increased friction and without any altered inertia of any origin, in particular without any problems. The acceleration and/or deceleration of the rotor can be conducted under laboratory conditions, for example using clear water. The term of the dynamic rotor model of the centrifugal pump described in the following is defined for example as a friction term, a hydraulic torque term and/or an inertia term. The acceleration and/or deceleration of the rotor of the centrifugal pump for detecting the at least one fault parameter preferably takes place during the regular operation of the centrifugal pump, for example when pumping waste water.

A centrifugal pump is generally referred to as a flow machine that utilizes a rotary motion and dynamic forces to convey predominantly liquids as fluid. The centrifugal pump is preferably configured as a waste water pump. In addition to a tangential acceleration of the liquid, a centrifugal force in radial flow is used for pumping in the centrifugal pump, so that such pumps are also referred to as centrifugal pumps. The centrifugal pump is preferably used for a hydraulic system in a building or other applications.

During the regular operation of the centrifugal pump, a housing of the motor of the centrifugal pump can be arranged above the pump housing, in which the impeller driven by the motor via the shaft is provided for conveying the liquid, whereby the housing of the motor can be connected to the pump housing in a fixed position and/or configured in one piece. The centrifugal pump and the motor can also each have their own shaft, wherein the shafts can be connected to one another via a coupling. Preferably, the shaft protrudes from the housing of the motor into the pump housing on a drive side and/or is fixed to the shaft on the drive side of the impeller. Accordingly, an inlet for the liquid to be conveyed can preferably be arranged below or at the bottom of the pump housing.

The liquid preferably includes water or another liquid medium such as waste water, for example. The liquid may contain solids such as impurities or waste of any kind, in particular feces, sediments, dirt, sand, or even small pieces of wood, undergrowth, textiles or rags or the like. Preferably, the housing of the motor and/or the pump housing is made of metal, in particular cast iron or stainless steel, ceramic and/or plastic. As already mentioned, in the context of the invention, the acceleration and/or deceleration of the rotor in the normal state for quantifying the at least one term of the dynamic rotor model of the centrifugal pump means in particular during a regular, fault-free operation of the centrifugal pump, namely when the centrifugal pump conveys a fluid as a liquid, which may be fresh water or may be mixed with the aforementioned portion of solids. The fault state includes, in particular, a malfunction, bearing damage including wear and/or ageing, seal damage including wear and/or ageing, a particularly large change in temperature, a consequence such as expansion and/or a change in viscosity, an incorrect alignment of pump components, a consequence such as misalignment and/or a change in gap size, a blockage inside the centrifugal pump, particularly at different points, a corrosion effect, a deposit effect, multi-component fluids in the impeller, multiphase or cavitating fluids in the impeller, an unknown increase in friction, etc.

According to a preferred development, the method includes the step:

According to this development, an unblocking routine suitable for correcting the anomaly or the blockage is selected based on the determined anomaly, for example in the case of a blockage, by means of which the centrifugal pump can be transferred from the fault state back to the normal state as quickly as possible. Preferably, the selection of the unblocking routine and/or the transfer of the centrifugal pump from the fault state to the normal state is automated, in particular by the computer-based control system. Such an automated transfer can be achieved, for example, by the unblocking routine includes multiple changes to the direction of rotation and/or rotational speed of the rotor. It may also be expedient for the centrifugal pump to be transferred from the fault state to the normal state manually, for example through the intervention of a user. For example, such a manual transfer can be achieved by replacing a damaged impeller.

According to a further preferred embodiment, quantifying the dynamic rotor model, which is in particular force-based, includes detecting a braking torque of the normal state, in particular at least one friction term, in particular a hydraulic torque term, and/or in particular time-dependent, as a function of an angular velocity of the rotor, and/or quantifying the dynamic rotor model, which is in particular force-based, includes detecting a total inertia of a rotating system of the centrifugal pump in the normal state, in particular including a liquid moved proportionally by the centrifugal pump. The quantification of the dynamic rotor model, in particular the force-based dynamic rotor model, is carried out for the normal state, in particular under laboratory conditions, wherein in particular all braking torques of the rotor or the centrifugal pump are determined or measured in advance. More preferably, quantifying the dynamic rotor model, in particular the force-based dynamic rotor model, includes detecting a braking torque of the normal state, consisting in particular of a total friction term and a torque term, in particular a hydraulic torque term, all in particular depending on the angular velocity of the rotor as a function of time, as well as detecting the total inertia of the rotating system in the normal state, including proportionally moved liquid.

According to another preferred development, the quantifying is carried out taking into account a pump characteristic curve, taking into account a system characteristic curve, in particular taking into account a geodetic height difference, and/or taking into account a gate valve, a valve, a bypass and/or a non-return flap and in particular a position of the valve and/or taking into account a filling level of a pipeline and/or length of the pipeline, a liquid temperature, a liquid viscosity, a liquid density, a pressure difference, a volume flow, a pump efficiency and/or a degree of valve opening. Data determined in this way can be stored in a database for a specific type of centrifugal pump in order to be used in a comparison with the normal state, in particular in the fault state. The proposed method can be used in particular with a closed pressure-side valve or closed non-return flap in order to produce a repeatable and comparable state, virtually independently of the system. Furthermore, machine learning or artificial intelligence methods can be used to further process the fault parameters, in particular for classification, after carrying out a plurality of experiments and subsequently analyzing the results.

According to a further preferred embodiment, the dynamic rotor model includes a braking torque of the normal state dependent on a rotational speed and/or angular velocity according to the following equation:

The equation described above combines all braking torques of the centrifugal pump in the normal state to form a total braking torque.

According to another preferred development, the dynamic rotor model, according to the following equation, includes in the normal state an inertia term and a braking torque on the left-hand side of the equation and a time-dependent motor torque on the right-hand side of the equation,

According to a further preferred embodiment, detecting the dynamic rotor model in the normal state includes calculating and/or experimentally determining an inertia moment. In particular, the detection of the dynamic rotor model in the normal state includes detecting the inertia moment of an entire rotating system of the centrifugal pump, in particular including additive inertias due to liquid in the environment of the rotor, for example by experimental determination in the laboratory or on the basis of a calculation.

According to another preferred development, solving the inverse problem includes classifying the anomaly, the normal state and/or the fault state. Based on the classification of the anomaly, a suitable measure can be selected, manually or by automation, to correct the anomaly. According to a further preferred embodiment, the centrifugal pump is transferred from the fault state to the normal state based on the classification of the anomaly and/or the fault state. Ideally, based on the classification in the case of a blockage, for example, an unblocking routine suitable for the classification can be selected so that the centrifugal pump can be transferred from the fault state back to the normal state after the unblocking routine has been used.

According to another preferred embodiment, the at least one fault parameter includes a breakaway torque and/or a static frictional torque of the fault state and/or the acceleration of the rotor for detecting the fault parameter includes increasing a motor torque from zero until the rotor is moved for the first time, wherein a static frictional torque of the anomaly results from a current motor torque at the first movement minus a breakaway torque of the normal state. According to a further preferred embodiment, the at least one fault parameter includes a breakaway torque and/or a static frictional torque of the fault state and/or the acceleration of the rotor for detecting the fault parameter includes increasing a motor torque from zero up to a first movement of the rotor, wherein a static frictional torque of the anomaly results from a current motor torque at the first movement minus a breakaway torque of the normal state. Preferably, a potential additional breakaway torque of the anomaly is determined first of all. For this purpose, the motor torque can be slowly increased continuously from zero until the rotor moves for the first time. The breakaway torque of the normal state is subtracted from this current motor torque so that the static frictional torque of the anomaly is obtained.

According to another preferred development, the method includes the step:

Vanishingly small means in particular ≥1 and ≤100 rotations of the rotor per minute, preferably ≥1 and ≤10 rotations of the rotor per minute.

In particular, the initial movement of the motor represents a breakaway. The angle of rotation of the rotor can be measured directly or calculated using an integration method.

According to a further preferred embodiment, the method includes the step:

According to another preferred development, the method includes the step:

According to a further preferred embodiment, the method includes the step:

According to another preferred development, the method includes the step:

According to a further preferred embodiment, the method includes the step:

According to another preferred embodiment, the method includes the step:

According to a further preferred embodiment, the method includes the step:

According to another preferred development, the method includes the step:

According to a further preferred embodiment, the normal state can be learned and/or the rotor model can be used to determine the fault parameters in different ways. The normal state of the centrifugal pump, in particular with regard to run-up and run-down, can be determined for each individual case and stored in the form of a characteristic curve. The normal state of the centrifugal pump, in particular with regard to run-up and run-down, can also be determined in advance for different applications and stored in the form of characteristic curves or characteristic diagrams for later selection. Finally, the normal state and the fault state of the centrifugal pump during run-up and/or run-down can always be analyzed when the slide valve is closed, in particular when the valve on one pressure side of the centrifugal pump is closed, wherein the normal state is saved and stored in the database.

According to another preferred development, the method includes the step:

According to a further preferred embodiment, the normal state can be defined by the fact that all fault parameters are smaller in value than the respective threshold values, i.e. the value is close to zero in particular. In particular, the normal state represents the centrifugal pump at the time of its delivery or when put into operation in a respective system or in regular operation without malfunctions and/or without ageing effects such as wear. According to another preferred development, the fault state is defined by the fact that at least one fault parameter is greater in value than or equal to a respective threshold value, i.e. its value is significantly different from zero.

The fault state can in particular represent bearing damage, including wear, seal damage including wear, and/or a particularly in temperature and its consequences such as expansion and/or changes in viscosity, incorrect alignment of pump components and consequences such as misalignments and/or changes in gap sizes, and/or blockages inside the centrifugal pump, in particular at different points, further wear effects, corrosion effects, deposit effects, and/or the presence of fluids with several components and/or phases inside the pump. The threshold values can be defined in advance experimentally or based on existing experience.

According to another preferred development, time signals of torque, angle of rotation and angular velocity can be recorded by hardware sensors and/or soft sensors. Hardware sensors are understood in particular to be sensors that measure variables directly as a function of time, wherein a sensor for the combined measurement of all relevant variables is also conceivable. In particular, soft sensors are understood to be sensors that allow the measurement of basic signals from the motor and/or the frequency inverter adapted to the respective motor technology. A combination of hardware sensors and soft sensors is also conceivable.

shows a schematic view of a centrifugal pumpfor carrying out a method described in the following for detecting, determining and/or classifying an anomaly and, in particular, in the event of a blockage, for subsequently unblocking the centrifugal pumpaccording to a preferred exemplary embodiment of the invention.

In a conventional manner, the centrifugal pumphas a pump housingwith a suction openingas the inlet, which is arranged at the bottom of the pump housingin the Figure. A rotoris provided in the pump housing, which rotor extends vertically in the drawing. The rotoris part of a motor, only partially shown, which is arranged opposite the suction opening. An impelleris provided facing the suction opening, which impeller is driven by the motorvia the rotor. Furthermore, the centrifugal pumphas a microprocessor-based control unit, which is only indicated in.

Lastly, the centrifugal pumphas one or more sensorsfor quantifying at least one term of a dynamic rotor model and/or for detecting at least one fault parameter of the centrifugal pump. The sensoris configured accordingly as an acceleration and/or vibration sensor, in particular as a 3-axis acceleration and/or vibration sensor, as a pressure sensor and/or as a current sensor, and/or as a sensor for determining a motor torque, an angle of rotation and/or an angular velocity or a rotational speed. In the case of a configuration as an acceleration and/or vibration sensor, the sensoris provided in particular in contact, directly adjacent and/or rigid, with a metal plate for example, in particular close to a respective bearing point, on the motor, assigned to the rotor, on the pump housing, on a motor housing of the motorand/or assigned to the impeller. In the case of a pressure sensor, the sensoris provided on the pressure side and/or suction side, in particular at the suction opening. In the case of a current sensor, the sensormeasures a motor current received by the motor.

The computer-implemented method described below for detecting, determining and/or classifying the anomaly of the centrifugal pumpis carried out by a processor and/or computer, not shown, in particular the control unit. In principle, the method uses a mathematical-physical approach for analyzing pump behavior during the acceleration and/or deceleration of the rotor, in particular during a run-up or run-down time of the motor. The approach consists essentially of three components: training a digital twin with reference to a normal state, identifying anomaly parameters by solving an inverse problem and classifying anomalies using the identified parameters.

Specifically, the method for detecting and/or determining the anomaly of the centrifugal pumpincludes the following steps:

Based on the determined anomaly, the centrifugal pumpcan in particular be automatically or manually transferred from the fault state back to the normal state.

The dynamic rotor model of the centrifugal pump, which takes into account potential anomalies or malfunctions as variable terms, is described by the following physical equation of motion: