Method for adjusting and / or calibrating flow meter and flow meter

Abstract

The invention relates to a method for adjusting and / or calibrating a flow meter, comprising the following method steps:-generating an at least intermittent dynamic flow curve in a line, the flow curve showing a continuous increase in flow during a first time interval; -determining a flow curve during a first time interval by means of a reference flow meter, a time value being assigned to the measured flow value, the time value being determined by means of a reference clock, in particular a reference flow meter,-determining a flow curve during the first time interval by means of a flow meter, the time value being assigned to the measured flow value, the time value being determined by means of a reference clock, in particular a reference flow meter; wherein a time value is also assigned to the measured flow value, the time value being determined by means of a flow meter clock, in particular a flow meter; and adjusting the flow curve determined by means of the flow meter to the flow curve determined by means of the reference flow meter in a first time interval in a particularly iterative manner. The invention also relates to a flow meter.

Description

Technical Field

[0001] The invention relates to a method for adjusting and / or calibrating a flow meter and to a flow meter for determining the flow rate of a flowable medium. Background Art

[0002] Especially in the adjustment and calibration technology of liquid and gas flow meters, the test object (the flow meter to be adjusted / calibrated) is compared with a reference. The comparison is made by causing the medium (liquid or gas) to flow first through the reference and then through the test object or in the opposite order. Different flow rates (i.e. flow rates, mass flow rates, etc.) are approached at a specific point and remain stable for a certain period of time. This process is called static adjustment / calibration. The synchronization between the test object and the reference is performed via a synchronization signal. Adjusting and stabilizing different flow rates is time-consuming and prolongs the calibration and adjustment process. Summary of the invention

[0003] The object of the present invention is to solve this problem.

[0004] This object is achieved by a method according to claim 1 and by a flow meter according to claim 9 .

[0005] The method for adjusting and / or calibrating a flow meter according to the present invention comprises the following method steps:

[0006] - generating a flow curve as a line, which is at least intermittently dynamic,

[0007] Therein, the flow curve shows a continuous increase in flow in the first time interval;

[0008] - determining a flow curve during a first time interval by means of a reference flow meter,

[0009] where a reference time value is assigned to the measured reference flow value,

[0010] wherein the time value is determined with the aid of a reference clock, in particular a reference flow meter,

[0011] - determining a flow curve during a first time interval by means of a flow meter,

[0012] Here, time values ​​are also assigned to the measured flow values,

[0013] wherein the time value is determined by means of a flow meter clock, in particular a flow meter;

[0014] In a first time interval, the flow rate profile determined by means of the flow meter is adjusted, in particular iteratively, to the flow rate profile determined by means of the reference flow meter.

[0015] An advantage of the method according to the invention is that no precise controller has to be used to set the desired flow rate. Adjustment and / or calibration times are significantly reduced, since stabilization and adjustment of individual static flows is not necessary.

[0016] Furthermore, the number of adjustment and control points can be increased (increase in the density of measured values) and a more complete picture of the flow range is created. As a result of recording the two flow curves and the differences between the reference and the test object and performing the adjustment according to the two flow curves, the data can be used for further offline evaluations. This means, for example, that recommendations for adjustments or flow curves can be developed with the aid of machine learning methods. This requires a sufficient database created in this way. This can potentially minimize the "overshoot" of the target value.

[0017] During calibration, adjusting the two flow curves involves determining the deviation between the two determined flow curves. According to DIN 1319-1, calibration does not involve any intervention that would change the flow meter. Adjusting the meter based on the results of the calibration is defined as adjustment. During adjustment, adjusting the two flow curves results in a correction factor that must be applied to the determined flow curve of the flow meter so that the flow curve of the reference flow meter is matched.

[0018] The flow meter is in particular a Coriolis flow meter, an ultrasonic flow meter, a vortex flow meter, a thermal flow meter and / or a magnetic inductive flow meter. The reference flow meter may be different from the flow meter to be calibrated / adjusted.

[0019] Advantageous embodiments of the invention are subject matter of the dependent claims.

[0020] One embodiment provides that the temporal flow rate variation in the first time interval deviates from zero.

[0021] One embodiment provides that the reference clock and the instrument clock are synchronized in time.

[0022] One embodiment provides that the reference clock and the instrument clock comply with a precision time protocol, in particular a precision time protocol according to IEEE 1588 or 802.1AS.

[0023] The Precision Time Protocol (PTP) is a network protocol that regulates the synchronization of the time settings of multiple devices in a computer network in order to achieve high local accuracy. PTP is defined in IEEE 1588 and adopted in IEC 61588. According to the present invention, the reference flow meter and the flow meter to be adjusted / calibrated are located in the network and each has a communicating clock. The clock with the most accurate time is the master clock. During operation, the master clock sends a time signal to the slave clock so as to determine the delay between the master clock and the slave clock. The master clock (ie, the reference clock) does not necessarily have to be stored in the reference flow meter in space. The reference flow meter can also have a slave clock that communicates with the master clock.

[0024] One embodiment provides that the regulation is performed by means of dynamic time warping.

[0025] Dynamic Time Warping is an algorithm for determining the similarity between two time series, ie, in this case, two determined time flow curves.

[0026] One embodiment provides for a flow profile having a second time interval prior to a first time interval for applying a flow pulse,

[0027] In this case, a determination and / or adjustment of the time delay between two determined flow curves takes place in the second time interval.

[0028] The injection of a flow pulse results in a clear and distinct feature in each of the two flow curves, which can be assigned to a single common event. For example, the flow pulse can be a step in the flow curve, which is caused by the flow increasing for a short time and then remaining constant. However, other shapes for the flow pulse are also conceivable, such as a temporary sawtooth curve. This can be achieved with a controllable pump or a controllable valve. The flow pulse can also be generated via a loudspeaker mounted outside the pipeline, with the flow meter and the reference flow meter also being arranged in the pipeline.

[0029] One embodiment provides that the flow rate profile has, after the first time interval, a third time interval in which the flow rate at least partially decreases continuously,

[0030] Therein, the third part has at least one control point, at which the flow rate determined by means of the flow meter is compared with the flow rate determined by means of the reference flow meter.

[0031] This has the advantage that it is possible to check, for example, whether sufficient regulation has taken place. If the flow curves deviate from each other when the flow decreases, then regulation can be continued even when the flow decreases, or the flow can be increased again and regulation continued.

[0032] Alternatively, the flow meter may subsequently be adjusted or calibrated again with the flow curve or using an alternative flow curve.

[0033] One embodiment includes the following method steps:

[0034] -Determination of the dynamic calibration factor of the flow meter based on two determined flow curves.

[0035] The dynamic calibration factor is stored in the flow meter and can be used as an independent factor or in combination with other calibration factors to determine the flow rate. In addition to the dynamic calibration factor, a static calibration factor can also be provided, which is used when the flow to be monitored changes only slightly. On the other hand, the dynamic calibration factor can be used whenever an event occurs in the flow that leads to (strong) flow fluctuations (e.g. opening of a valve), i.e. large flow changes within a short time interval (a few seconds).

[0036] Alternatively, a deviation factor may be determined which provides information about the deviation of the flow meter to be calibrated.

[0037] For the flow meter according to the invention for determining the flow of a medium, an adjustment and / or calibration of the flow meter is carried out by means of the method according to the invention for adjustment and / or calibration.

[0038] One embodiment provides that at least one statically determined calibration factor is stored in the flow meter,

[0039] At least one of the dynamically determined calibration factors is stored in the flow meter.

[0040] This has the advantage that accurate measurements can be ensured over a wide spectrum of flow rates. The measurement circuitry stored in the flow meter (including a microcontroller and electronic logic elements) can be configured to determine the flow rate based on a dynamic calibration factor or based on a static calibration factor.

[0041] Instead of statically controlling different flow rates, dynamic flow curves are used. The measured values ​​of the reference (reference flow meter) and the test object (flow meter) are recorded synchronously. PTC (Precision Time Protocol) can be used for this purpose. While the flow curve is being run, the deviation of the test object from the reference is calculated and automatically corrected (iterative method) until the determined measured values ​​of the test object are within the desired tolerance. The determined flow curves are mathematically superimposed. The waiting time of the system can be determined dynamically, for example, by applying a flow pulse at the beginning and determining the step response. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The present invention is explained in more detail with reference to the following drawings, in which:

[0043] Figure 1 A schematic diagram showing an adjustment / calibration system; and

[0044] Figure 2 An example of a flow curve (flow as a function of time) is shown. DETAILED DESCRIPTION

[0045] Figure 1A schematic diagram of an adjustment / calibration system is shown. The flow meter 1 is arranged in front of the reference flow meter 3 in the pipeline, i.e. the medium first passes through the flow meter 1 and then through the reference flow meter 3. Alternatively, the reference flow meter 3 can be positioned upstream of the flow meter 1, opposite to the flow direction. It should be understood that in addition to the flow meters 1 and 3 shown, other components such as pumps, piston calibrators, medium containers, etc. are also part of the adjustment / calibration system. In addition, the adjustment / calibration system does not have to be a factory-installed system that is only used to adjust and / or calibrate the flow meter. Alternatively, the flow meter 1 is configured to perform the method for adjustment and / or calibration according to the present invention. It is also equipped with a flow meter clock 2 (slave clock). The currently determined flow measurement value is provided with a time value determined by means of the flow meter clock 2. The reference flow meter 3 is also equipped with a flow meter clock 4 (slave clock). The flow measurement value measured by means of the reference flow meter 3 is also provided with a time value determined via the flow meter clock 4. The two flow meter clocks 2, 4 communicate with the reference clock 5 (master clock). The reference clock 5 is configured to synchronize the two flow meter clocks 2, 4 in terms of time. In this process, a precise time protocol according to IEEE 1588 or 802.1AS is used. A calibration factor can then be derived from the determined flow curves (flow as a function of time) of the flow meter and the reference flow meter. This can be done iteratively while recording the flow curves. An example of this is shown in Figure 2 Shown in.

[0046] Figure 2 An embodiment of a flow curve X (flow rate as a function of time) of a flow meter and a flow curve Y of a reference flow meter is shown. The two flow curves X, Y are divided into three time intervals A, B, C. Therefore, the temporal flow change in time interval A is always greater than zero. During the first time interval A, the flow meter and the reference flow meter measure the flow rate. A time value is assigned to each flow measurement value. This then results in a flow curve. There is a second time interval B before the first time interval A. In the second time interval B, the flow rate at least temporarily jumps and then remains constant for a short period of time. This is a flow pulse in the form of a step (see I). This is used to determine the delay or time delay between the two flow curves X, Y. Thereafter, the flow rate increases continuously again. It can be seen that there is a deviation in the time distribution of the absolute flow rate and the determined flow measurement values ​​between the flow curve X and the flow curve Y. This becomes particularly evident through the flow pulse. According to the invention, this deviation is reduced during the measurement of the flow curve (see II) until the corresponding determined flow measurement values ​​are recorded synchronously and only a tolerable minimum deviation exists between the corresponding determined flow measurement values ​​(see III). The adjustment can be done iteratively and / or with the aid of dynamic time warping and provide a dynamic calibration factor for the flow meter. In a third time interval C, the flow rate continues to decrease. While decreasing the flow rate, it is verified at various control points (see two points in IV) whether the determined flow measurements substantially match.

Claims

1. A method for adjusting and / or calibrating a flow meter (1), comprising the following method steps: - generating a flow curve as a line, said flow curve being at least intermittently dynamic, in, The flow curve shows a continuous increase in flow rate within a first time interval (A); - determining said flow curve during said first time interval (A) by means of a reference flow meter (3), where a reference time value is assigned to the measured reference flow value, wherein the time value is determined with the aid of a reference clock (5), in particular the reference flow meter (3), - determining the flow curve during the first time interval (A) by means of the flow meter (1), Here, time values ​​are also assigned to the measured flow values, wherein the time value is determined by means of a flow meter clock (2), in particular the flow meter (1); - within the first time interval (A), the flow rate profile determined by means of the flow meter (1) is adjusted, in particular iteratively, to the flow rate profile determined by means of the reference flow meter.

2. The method according to claim 1, wherein: in, The flow rate variation in the first time interval (A) deviates from zero.

3. A method according to claim 1 or claim 2. in, The reference clock (5) and the flow meter clock (2) are time synchronized.

4. The method according to claim 3, wherein: in, The reference clock (5) and the flow meter clock (2) comply with a precision time protocol, in particular a precision time protocol according to IEEE1588 or 802.1AS.

5. The method according to at least one of the preceding claims, in, The adjustment is done by means of dynamic time warping.

6. The method according to at least one of the preceding claims, in, The flow curve has a second time interval (B) before the first time interval (A) during which the flow pulse is applied, In this case, a determination and / or adjustment of the time delay between two determined flow curves takes place in the second time interval (B).

7. The method according to at least one of the preceding claims, in, The flow rate curve has a third time interval (C) after the first time interval (A), in which the flow rate at least partially decreases continuously, The third time interval (C) has at least one control point, at which the flow rate determined by means of the flow meter (1) is compared with the flow rate determined by means of the reference flow meter (3).

8. The method according to at least one of the preceding claims, comprising the following method steps: - Determining a dynamic calibration factor of the flow meter (1) based on two determined flow curves.

9. A flow meter (1) for determining the flow rate of a medium, It is characterized in that The adjustment and / or calibration of the flow meter (1) is performed by a method for adjustment and / or calibration according to one of the preceding claims.

10. The flow meter (1) according to claim 9, wherein: in, At least one statically determined calibration factor is stored in the flow meter (1), Therein, at least one dynamically determined calibration factor is stored in the flow meter (1).

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