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

Abstract

The invention relates to a method for adjusting and / or calibrating a flow meter, comprising the method steps of: - generating an at least intermittently dynamic flow profile in a line, wherein the flow profile shows a continuous increase in flow within a first time interval; - determining the flow profile by means of a reference flow meter during the first time interval, wherein a time value is assigned to a measured flow value, wherein the time value is determined by means of a reference clock, in particular of the reference flow meter, - determining the flow profile by means of the flow meter during the first time interval, wherein a time value is also assigned to a measured flow value, wherein the time value is determined by means of a flow meter clock, in particular of the flow meter; and - adapting the flow profile determined by the flow meter, in particular iteratively, to the flow profile determined by the reference flow meter within the first time interval. The invention also relates to a flow meter.

Description

[0001] Method for adjusting and / or calibrating a flowmeter and flowmeter

[0002] The invention relates to a method for adjusting and / or calibrating a flow measuring device and a flow measuring device for determining a flow of a flowable medium.

[0003] Especially in the adjustment and calibration of liquid and gas flowmeters, the test objects (the flowmeter to be adjusted / calibrated) are compared with references. The comparison is performed by having a medium (liquid or gas) first flow through a reference and then through the test object, or in reverse order.

[0004] Different flow rates (i.e., flow velocities, mass flow rates, etc.) are selectively approached and held stable for a specific period of time. This procedure is called static adjustment / calibration. Synchronization between the test sample and the reference is achieved via a synchronization signal. Adjusting and stabilizing the various flow rates is time-consuming and prolongs the calibration and adjustment process.

[0005] The invention is based on the object of remedying the problem.

[0006] The object is achieved by the method according to claim 1 and the flow meter according to claim 9.

[0007] The method according to the invention for adjusting and / or calibrating a flow measuring device, comprising the method steps:

[0008] - generating an at least interval-dynamic flow profile in a line, wherein the flow profile has a continuous increase in flow within a first time interval;

[0009] - Determining the flow profile by means of a reference flow meter during the first time interval, whereby a measured reference flow value is assigned a reference time value, whereby the time value is determined by means of a reference clock, in particular the reference flow meter,

[0010] - Determining the flow profile by means of the flow meter during the first time interval, wherein a measured flow value is also assigned a time value, wherein the time value is determined by means of a flow meter clock, in particular of the flow meter;

[0011] - Adapting the flow profile determined by means of the flow meter, in particular iteratively, to the flow profile determined by means of the reference flow meter within the first time interval.

[0012] The advantage of the method according to the invention is that no precise controllers are required to set the desired flow rate. Adjustment and / or calibration times are significantly reduced because stabilization and adjustment of individual static flow rates is not necessary.

[0013] Furthermore, the number of adjustment and control points can be increased (increased measurement density), creating a more complete picture of the flow range. By recording the two flow profiles, as well as the difference between the reference and the test sample, and the adjustment performed based on the two flow profiles, data is available for further offline evaluations. This allows, for example, suggestions for adjustments or flow profiles to be developed using machine learning methods. This requires a sufficient database, which is created in this way. This could potentially minimize overshooting of the target value.

[0014] During calibration, adjusting the two flow profiles involves determining any deviation between the two determined flow profiles. According to DIN 1319-1, calibration does not involve any intervention that alters the flowmeter. Adjusting the flowmeter based on the calibration results is defined as adjustment. During adjustment, adjusting the two flow profiles results in a correction factor, which must be applied to the determined flow profile of the flowmeter so that it matches the flow profile of the reference flowmeter.

[0015] Flowmeters include, in particular, Coriolis, ultrasonic, vortex, thermal, and / or magnetic-inductive flowmeters. The reference flowmeter may differ from the flowmeter to be calibrated / adjusted.

[0016] Advantageous embodiments of the invention are the subject of the subclaims.

[0017] One embodiment provides that a temporal flow change in the first time interval deviates from zero.

[0018] One embodiment provides that the reference clock and the measuring device clock are time synchronized.

[0019] One embodiment provides that the reference clock and the measuring device clock are subject to a precision time protocol, in particular the precision time protocol according to IEEE1588 or 802.1 AS.

[0020] 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 invention, the reference flowmeter and the flowmeter to be adjusted / calibrated are located in a network and each have communicating clocks. The clock with the most precise time is the master clock. During operation, the master clock sends time signals to a slave clock in order to determine the delays between the master and slave clocks. The master clock, i.e. the reference clock, does not necessarily have to be physically stored in the reference flowmeter. The reference flowmeter can also have a slave clock that communicates with the master clock.One embodiment provides for the adaptation to be carried out using dynamic time warping.

[0021] Dynamic Time Warping is an algorithm used to determine similarities between two temporal sequences - in this case the two determined temporal flow profiles.

[0022] One embodiment provides that the flow profile has a second time interval before the first time interval in which a flow pulse is impressed, wherein in the second time interval a determination and / or adjustment of a time delay between the two determined flow profiles takes place.

[0023] The application of the flow pulse results in each of the two flow profiles having a unique and distinct characteristic that can be assigned to a single common event. The flow pulse can, for example, be a step in the flow profile resulting from the flow being increased briefly and then kept constant. However, other shapes for the flow pulse are also conceivable, such as a temporary sawtooth profile. This can be achieved using a controllable pump or a controllable valve. The flow pulse can also be generated using a loudspeaker attached externally to the pipeline in which the flow meter and the reference flow meter are also located.

[0024] One embodiment provides that the flow profile has a third time interval after the first time interval in which the flow continuously decreases at least in sections, wherein the third section has at least one checkpoint at which the flow determined by means of the flow meter is compared with the flow determined by means of the reference flow meter. The advantage of this is that it can thus be checked whether, for example, sufficient adjustment has been carried out. If the flow profiles deviate from one another when the flow decreases, the adjustment can either be carried out further - even when the flow decreases - or the flow is increased again and the adjustment carried out again.

[0025] Alternatively, the flow meter can subsequently be adjusted or calibrated again using the flow profile or an alternative flow profile.

[0026] One embodiment includes the following procedural step:

[0027] - Determination of a dynamic calibration factor for the flow meter depending on the two determined flow profiles.

[0028] The dynamic calibration factor is stored in the flowmeter and can be used as a standalone 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 be provided, which is used when the flow rate to be monitored changes only slightly. The dynamic calibration factor, on the other hand, can always be used when events occur in the flow rate that lead to (significant) flow fluctuations (e.g., valve opening), i.e., large flow changes within a short time interval (a few seconds).

[0029] Alternatively, a deviation factor can be determined, which provides information about the deviation of the flow meter to be calibrated.

[0030] For the flow meter according to the invention for determining a flow of a medium, an adjustment and / or calibration of the flow meter is carried out by means of the method for adjustment and / or calibration according to the invention.

[0031] One embodiment provides that at least one statically determined calibration factor is stored in the flow measuring device, wherein at least one dynamically determined calibration factor is stored in the flow measuring device.

[0032] The advantage of this is that it ensures accurate measurement values ​​across a wide flow range. A measuring circuit embedded in the flowmeter (comprising a microcontroller and electronic logic elements) can be configured to determine the flow rate either based on the dynamic calibration factor or based on the static calibration factor.

[0033] Instead of statically controlling different flow rates, a dynamic flow profile is run instead. The measured values ​​of the references (reference flow meter) and the test objects (flow meter) are recorded synchronously. A PTC (Precision Time Protocol) can be used for this. While the flow profile is run, the deviation of the test object from the reference is calculated and automatically corrected (iteration process) until the measured values ​​of the test object are within the desired tolerance. The determined flow profiles are mathematically superimposed. System latency times can be determined dynamically, e.g., by applying a flow pulse at the beginning and determining the step response.

[0034] The invention is explained in more detail with reference to the following figures. They show:

[0035] Fig. 1 : a schematic representation of an adjustment-Zcalibration system; and

[0036] Fig. 2: a design of a flow profile (flow as a function of time).

[0037] Fig. 1 shows a schematic representation of an adjustment / calibration system. A flow meter 1 is arranged upstream of a reference flow meter 3 in a pipeline, i.e. the medium first flows through the flow meter 1 and then the reference flow meter 3. Alternatively, the reference flow meter 3 can also be positioned upstream of the flow meter 1 against the flow direction. It is understood that in addition to the flow meters 1, 3 shown, other components - such as a pump, a piston prover, a medium container, etc. - are also part of the adjustment / calibration system. Furthermore, the adjustment / calibration system does not have to be a factory-assembled system that is only used for adjusting and / or calibrating flow meters. Alternatively, the flow meter 1 is set up to carry out the inventive method for adjustment and / or calibration.It is also equipped with a flowmeter clock 2 (slave clock). The currently measured flow values ​​are assigned a time value determined by the flowmeter clock 2. The reference flowmeter 3 is also equipped with a flowmeter clock 4 (slave clock). The flow values ​​measured by the reference flowmeter 3 are also assigned a time value determined by the flowmeter clock 4. Both flowmeter clocks 2 and 4 communicate with a reference clock 5 (master clock). The reference clock 5 is configured to synchronize the time of the two flowmeter clocks 2 and 4. The Precision Time protocol according to IEEE 1588 or 802.1 AS is used for this purpose.A calibration factor can then be derived from the determined flow profiles (flow rate as a function of time) of the flow meter and the reference flow meter. This can be done iteratively while recording the flow profiles. An example is shown in Fig. 2.

[0038] Fig. 2 shows a configuration of the flow profile X (flow as a function of time) of a flow meter and the flow profile Y of a reference flow meter. The two flow profiles X, Y are divided into three time intervals A, B, C. In a first time interval A, the flow increases continuously. Thus, 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. A time value is assigned to each flow measurement. This then results in the flow profile. Before the first time interval A there is a second time interval B. In the second time interval B the flow increases abruptly, at least for a time, and then remains constant for a short period of time. This is a flow pulse (see I) in the form of a step.This serves to determine a latency time or a time delay between the two flow profiles X, Y. After that, the flow increases continuously again. It can be seen that there are deviations in the absolute flow and in the temporal assignment of the determined flow measurement values ​​between the flow profile X and the flow profile Y. This is particularly visible through the flow pulse. According to the invention, this deviation is reduced during the measurement of the flow profile (see II) until the respectively determined flow measurement values ​​are recorded synchronously and only a tolerable minimal deviation exists between the respectively determined flow measurement values ​​(see III). The adaptation can be done iteratively and / or using dynamic time warping and provides a dynamic calibration factor for the flow meter. In a third time interval C, the flow is continuously reduced.When reducing the flow, it is verified at individual control points (see two points in IV) whether the measured flow values ​​essentially agree.

Claims

PATENT CLAIMS 1 . Method for adjusting and / or calibrating a flow measuring device (1 ), comprising the method steps: - generating an at least interval-dynamic flow profile in a line, wherein the flow profile has a continuous increase in the flow within a first time interval (A); - Determining the flow profile by means of a reference flow meter (3) during the first time interval (A), wherein a reference time value is assigned to a measured reference flow value, wherein the time value is determined by means of a reference clock (5), in particular of the reference flow meter (3), - determining the flow profile by means of the flow measuring device (1) during the first time interval (A), wherein a time value is also assigned to a measured flow value, wherein the time value is determined by means of a flow measuring device clock (2), in particular of the flow measuring device (1); - adapting the flow profile determined by means of the flow meter (1), in particular iteratively, to the flow profile determined by means of the reference flow meter within the first time interval (A).

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

3. Method according to claim 1 or 2, wherein the reference clock (5) and the flow meter clock (2) are time-synchronized.

4. The method according to claim 3, wherein the reference clock (5) and the flow meter clock (2) are subject to a Precision Time Protocol, in particular the Precision Time Protocol according to IEEE1588 or 802.1AS.

5. Method according to at least one of the preceding claims, wherein the adaptation is carried out by means of dynamic time warping.

6. Method according to at least one of the preceding claims, wherein the flow profile has a second time interval (B) before the first time interval (A) in which a flow pulse is impressed, wherein in the second time interval (B) a determination and / or adjustment of a time delay between the two determined flow profiles takes place.

7. Method according to at least one of the preceding claims, wherein the flow profile after the first time interval (A) has a third time interval (C) in which the flow decreases continuously at least in sections, wherein the third time interval (C) has at least one control point at which the flow rate determined by means of the flow measuring device (1) Flow is compared with the flow determined by the reference flow meter (3).

8. Method according to at least one of the preceding claims, comprising the method step: - Determination of a dynamic calibration factor for the flow meter (1 ) depending on the two determined flow profiles.

9. Flow meter (1) for determining a flow of a medium, characterized in that an adjustment and / or calibration of the flow meter (1) is carried out by means of a method for adjustment and / or calibration according to one of the preceding claims.

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

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