TESTING AND / OR CALIBRATION KIT FOR FLOW METERS AND METHOD FOR TESTING AND / OR CALIBRATION OF FLOW METERS

Description

[0001] The present invention relates to a testing and / or calibration setup for flow meters, in particular for ultrasonic flow meters, and a corresponding method for testing and / or calibrating such flow meters.

[0002] Approved flow meters are qualified and / or calibrated for their intended use (e.g., for billing) using a suitable test bench with sufficient precision. The test bench must provide the respective nominal diameter and intended flow rates for the corresponding flow meter (specifically, the "meter-under-test" (MUT)). Test benches with accuracies of <0.1% for large nominal diameters (>DN500) are rare.

[0003] There are various strategies for qualifying a flow meter. First, there is volumetric qualification, in which the actual flow is determined using a known reference volume via the MUT. Alternatively, there is gravimetric qualification, in which the actual flow is determined using a scale for a reference volume and the fluid density. The third qualification variant is the "master meter method," in which the actual flow is determined using a sufficiently accurate reference meter.

[0004] It should be noted that all known test methods measure in stationary operation or in a single pass. Stationary operation does not allow for the investigation of the frequency response of the flow. Furthermore, there is the challenge of ensuring the long-term stability of the reference flow being measured. Tests at low flow rates can be carried out over a period of hours, but this does not currently apply to measurements at high flow rates. Specifically, a specific volume flow is always generated in a single pass and only evaluated within the range of a target flow rate. Due to the selected test setup, only a very limited volume of fluid is available, which is moved from an outlet reservoir through the flow meter into a collecting reservoir. This means that, particularly with large nominal diameters (>DN500), only comparatively low or time-limited volume flows can be measured.

[0005] It is therefore an object underlying the invention to provide a test and / or calibration setup and a corresponding method for testing and / or calibration, by means of which flow meters for comparatively large nominal diameters can also be reliably and accurately tested and / or calibrated.

[0006] This object is achieved by a test and / or calibration setup according to claim 1 and a method according to claim 14. Advantageous developments of the invention can be found in the dependent claims.

[0007] Exemplary embodiments of known structures according to the preamble of claim 1 can be found in DE 10 2014 211 961 A1, FR 2 596 151 A1, US 3 177 699 A and CN 114 414 008 A.

[0008] Accordingly, a test and / or calibration setup according to the invention for flow meters, in particular for ultrasonic flow meters, comprises a U-tube arrangement with two at least partially vertical pipe sections and one at least partially horizontal pipe section, which connects the two vertical pipe sections to one another, in particular in their lower region, as well as a fluid which fills the at least partially horizontal pipe section and projects into the two at least partially vertical pipe sections to form fluid columns there. Furthermore, the test and / or calibration setup according to the invention comprises a drive unit which is designed to move the fluid along the U-tube arrangement, resulting in a volume flow of fluid through the at least partially horizontal pipe section and, at the same time, in an (opposing) variation in the height of the two fluid columns in the two at least partially vertical pipe sections.Finally, the testing and / or calibration setup according to the invention also comprises a control and evaluation unit designed to control the drive unit and monitor the behavior of the fluid in order to determine the actual flow rate generated through the horizontal pipe section. The at least partially horizontal pipe section has a testing and / or calibration area in which the flow meter to be tested and / or calibrated can be provided to measure the flow rate through the at least partially horizontal pipe section.The control and evaluation unit can be coupled to the flow meter to be tested and / or calibrated and is designed to compare the flow measured by the flow meter with the actually generated flow and to output a corresponding result and / or to calibrate the flow meter based on the actually generated flow, in particular automatically. The drive unit and the control and evaluation unit are designed to effect an oscillating, in particular a harmonically oscillating, variation in the height of the fluid columns in the two at least partially vertical pipe sections and thus a correspondingly oscillating flow through the at least partially horizontal pipe section.

[0009] The phrase "at least partially horizontal pipe section" is effectively understood to mean that said pipe section is at least not purely vertical, while the phrase "at least partially vertical pipe sections" is effectively understood to mean that said pipe sections are at least not purely horizontal. In other words, the orientation of the at least partially horizontal pipe section has at least a horizontal component, while the orientation of the at least partially vertical pipe sections has at least a vertical component. According to the invention, a U-tube arrangement with a predominantly (preferably actually) horizontal pipe section and two opposing predominantly (preferably actually) vertical pipe sections is preferred.However, it is also possible to incline the two at least partially vertical pipe sections by a specific angle from the vertical (since then a component of the pipe - i.e. a pipe section - also runs in the vertical direction). The at least partially horizontal pipe section can also comprise only the test and / or calibration area for the flow meter. Thus, within the meaning of the present invention, for example, a configuration in the shape of a V with a horizontal test and / or calibration area in the lower tip of the V is also a U-tube arrangement according to the claims. It is understood that the vertical pipe sections and the horizontal pipe section can be connected to one another by any desired shapes (intermediate pieces), as long as a fluid flow between the vertical pipe sections and the horizontal pipe section is possible.

[0010] This design offers several advantages. The resulting, particularly symmetrical, U-tube arrangement makes it easy to generate an oscillating flow through the flowmeter, which can be maintained using the respective potential energy of the fluid columns in the at least partially vertical pipe sections. Once set in motion by the drive unit, the fluid repeatedly "sloshes" back and forth in the U-tube arrangement, particularly with a damped sinusoidal motion profile. The energy-saving, repeatable change in flow direction enables simple and efficient multiple measurements with the flowmeter. This allows for more precise and reliable testing and / or calibration of the respective flowmeter compared to the single-pass measurement described above.The at least partially vertical alignment of the lateral pipe sections enables a space-saving setup in terms of the required footprint of such a test device, which essentially extends vertically. By varying the at least partially horizontal pipe section, the nominal diameter, flow rates, and frequencies of the fluid as it passes through the at least partially horizontal pipe section can be varied very easily and freely without having to modify the remaining test and / or calibration setup.

[0011] According to the present invention, the drive unit and the control and evaluation unit are designed to bring about an oscillating, in particular a harmonically oscillating, variation of the height of the fluid columns in the two vertical pipe sections and a correspondingly oscillating flow through the at least partially horizontal pipe section.

[0012] The aforementioned variation of the height of the fluid column in the two at least partially vertical pipe sections is possible due to their connection via the at least partially horizontal pipe section by actively varying the height of the fluid column in only one of the two at least partially vertical pipe sections. This, in turn, can be achieved very simply and reliably, for example, using a mechanically driven piston in one of the two at least partially vertical pipe sections. Alternatively, hydraulic or pneumatic designs would also be conceivable. In order to enable particularly accurate and precise control of the height of the fluid columns in the two at least partially vertical pipe sections, both at least partially vertical pipe sections can of course have a corresponding variation device, which then together form the claimed drive unit.Oscillating variation makes it easy to perform multiple measurement runs, significantly improving the measurement accuracy of the setup. Harmonic oscillating variation is particularly energy-efficient.

[0013] Preferably, the control and evaluation unit is designed to monitor and evaluate the behavior of the fluid over at least half a stroke period, in particular over several - preferably consecutive - stroke periods.

[0014] In concrete terms, this means that, in contrast to the current state of the art, the actual behavior of the fluid and in particular the flow rate (both by the evaluation and control unit and by the MUT) are monitored and evaluated even during the build-up and decay phases of the generated flow rate.

[0015] Specifically, this allows monitoring and evaluation of fluid velocities with a continuous temporal dependence, and thus flow rates, in a single test procedure. When monitoring and evaluating multiple stroke periods (i.e., vibration runs), a statistical evaluation, for example, in the form of an average, is performed across the multiple stroke periods. The accuracy of the setup increases with the square root of the number of stroke periods to the power of minus 1.

[0016] This allows for comprehensive testing and / or calibration of the flowmeter across the entire range of actual flow rates, without having to perform a separate measurement run for each intended flow. This, in turn, significantly increases the efficiency of testing and / or calibrating the respective flowmeter.

[0017] Additionally or alternatively, the drive unit and the control and evaluation unit are preferably designed to effect the oscillating variation of the height of the fluid columns in the two at least partially vertical pipe sections and a correspondingly oscillating flow through the at least partially horizontal pipe section with a specific, in particular adjustable, excitation frequency.

[0018] The variation in the excitation frequency allows for a simple and efficient determination of the flowmeter's behavior at different oscillation frequencies, i.e., the frequency response. This is not possible with conventional single-pass tests, but provides important information for the actual use of such flowmeters.

[0019] Furthermore, the drive unit and the control and evaluation unit are preferably designed to effect the oscillating variation of the height of the fluid columns in the two at least partially vertical pipe sections and thus a correspondingly oscillating flow through the at least partially horizontal pipe section with the resonance frequency of this movement.

[0020] By resonantly exciting the fluid's movement through the U-tube arrangement, the full potential of the test and / or calibration setup with regard to maximum flow rates can be exploited in a particularly efficient manner. The possibility of resonantly oscillating harmonic movement of the fluid through the U-tube arrangement is a particularly significant advantage of the inventive design.

[0021] Preferably, the control and evaluation unit for monitoring the behavior of the fluid is coupled to at least one intrinsic sensor, which determines intrinsic properties of the fluid in the U-tube arrangement. In particular, the at least one intrinsic sensor is designed to continuously determine a static pressure of the fluid in a specific region of the U-tube arrangement and / or a differential pressure of the fluid between two different regions of the U-tube arrangement.

[0022] The determined intrinsic properties of the fluid enable a reliable and accurate determination of the actual flow rate. The differential pressure determined, if any, represents, in particular, the differential pressure applied across the respective flow meter.

[0023] Preferably, the control and evaluation unit for monitoring the behavior of the fluid is coupled to at least one extrinsic sensor, which determines extrinsic properties of the fluid in the U-tube arrangement. In particular, the at least one extrinsic sensor is designed to continuously determine the height of the fluid column in at least one of the two at least partially vertical pipe sections and / or a position of the drive unit. The actual flow rate is then determined from the height and the known geometry of the U-tube arrangement.

[0024] As an alternative to the intrinsic properties described above, extrinsic properties also enable a relatively reliable and accurate determination of the actual flow rate generated. Extrinsic sensors are generally easier to handle than intrinsic sensors. A combination of intrinsic and extrinsic sensors provides particularly reliable and accurate results in determining the actual flow rate generated.

[0025] Preferably, the drive unit comprises at least one displacement device which is designed to displace the fluid in at least one of the two at least partially vertical pipe sections in order to move the fluid along the U-pipe arrangement.

[0026] Such a displacement device can in particular be of a mechanical, hydraulic and / or pneumatic nature and represents a particularly simple and reliable way of generating the respective flow.

[0027] The displacement device is preferably designed in the form of a hydraulic or pneumatic displacement device, in particular with a displacement piston movable along the respective at least partially vertical pipe section.

[0028] These specific implementations of the displacement device are very robust. Furthermore, in a configuration in which the two at least partially vertical pipe sections are equipped with such a displacement device, a coupling of the two displacement devices is possible, thus enabling particularly efficient oscillating operation of these two displacement devices.

[0029] As already indicated above, the drive unit preferably comprises at least one separate displacement device for each of the two at least partially vertical pipe sections.

[0030] This enables a particularly controlled and precise adjustment of the actually generated flow through the at least partially horizontal pipe section.

[0031] Preferably, the fluid is a liquid that is, in particular, largely incompressible. In particular, the fluid is water.

[0032] This enables particularly precise testing and calibration of the respective flow meter, with water being an advantageous, particularly inexpensive, freely accessible and non-toxic liquid.

[0033] Preferably, the test and / or calibration setup is designed as a stationary test bench. The nominal diameter of the at least partially horizontal pipe section is in particular in a range from 500 mm to 3,000 mm. In particular, the test and / or calibration setup is designed to generate a flow rate of up to 30,000 m³ / h. The two at least partially vertical pipe sections each have a height of 20 to 40 meters.

[0034] It has been shown that these specific embodiments are particularly suitable for implementing the present invention, in particular to exploit its full potential for the barely developed area of ​​large nominal diameters and large flow rates.

[0035] Preferably, the test and / or calibration setup is designed such that in each (permitted) operating state, the at least partially horizontal pipe section is completely filled with the fluid.

[0036] This prevents incorrect measurements by the flow meter. This requirement can be met, for example, by monitoring the height of the fluid columns in the two at least partially vertical pipe sections and ensuring a minimum height of both fluid columns via appropriate control of the drive unit. Alternatively, a buffer tank can be provided to prevent the occurrence of excessive amplitudes during harmonically oscillating movements of the fluid in the range of its resonant frequency, thus preventing at least partial emptying of the at least partially horizontal pipe section.

[0037] Preferably, the testing and / or calibration setup is designed to carry out the testing and / or calibration of the respective flow meter over a plurality of movement passes of the fluid through the at least partially horizontal pipe section, in particular at a specific excitation frequency.

[0038] Such a repetition of the measurement run makes it possible to increase the accuracy of the test and / or calibration carried out.

[0039] In particular, the test and / or calibration setup is designed to carry out the test and / or calibration of the respective flow meter by means of different movement sequences at different excitation frequencies.

[0040] Such a variation of the excitation frequencies allows for particularly comprehensive and reliable testing and / or calibration.

[0041] According to the invention, a method for testing and / or calibrating a flow meter, in particular with a test and / or calibration setup described above, comprises the following steps: Generation of a harmonically oscillating movement of a fluid through a substantially vertically oriented U-tube arrangement with one at least partially horizontal pipe section and two at least partially vertical pipe sections; determination of the flow rate actually generated through the at least partially horizontal pipe section; comparison of the determined actual flow rate with the flow rate measured by a flow meter provided on the at least partially horizontal pipe section and / or calibration of a flow meter provided on the at least partially horizontal pipe section based on the determined actual flow rate.

[0042] The determination of the flow rate actually generated can be carried out taking into account the actions taken to generate the movement of the fluid and / or with the aid of sensors which, however, are different from the flow meter to be tested and / or calibrated.

[0043] Such a method allows a particularly reliable and accurate testing and / or calibration of the respective flowmeter, as already explained above with reference to a corresponding test and / or calibration setup.

[0044] Preferably, the method further comprises replacing the at least partially horizontal pipe section with an at least partially horizontal pipe section with a different inner diameter and repeating the aforementioned method steps.

[0045] This enables a comparatively simple and efficient, even more comprehensive testing and / or calibration of the respective flow meter.

[0046] The invention is described below purely by way of example with reference to a drawing. In the drawing: FIG. 1 schematically shows a test and / or calibration setup according to an embodiment of the present invention.

[0047] Specifically, FIG. 1 schematically shows a test and / or calibration setup 1 with a U-tube arrangement consisting of two vertical pipe sections 3 and 5 and a horizontal pipe section 7. The horizontal pipe section 7 has a test and / or calibration area in which the flow meter MUT ("Meter Under Test") to be tested or calibrated, in particular in the form of an ultrasonic flow meter, is provided.

[0048] The horizontal pipe section 7 is completely filled and the two vertical pipe sections 3 and 5 are each filled with fluid up to a certain height, as indicated by the schematic waves in the two vertical pipe sections 3 and 5.

[0049] In the embodiment shown, the left vertical pipe section 3 opens into a buffer tank 9 at its upper end, while a displacement piston is provided in the right vertical pipe section 5 and is coupled to a corresponding drive (not shown).

[0050] The displacement piston, together with its drive, forms a displacement device of a drive unit 11 of the test and / or calibration setup. Said drive unit 11 is coupled to a control and evaluation unit (not shown).

[0051] Furthermore, the test and / or calibration setup 1 shown here comprises an extrinsic sensor in the form of a fill level sensor S for determining the fill level of the right vertical pipe section 5 and two intrinsic sensors in the form of an absolute value pressure sensor P and a differential value pressure sensor ΔP. All of these and possibly further sensors not shown are coupled to the control and evaluation unit in order to supply it with measured values ​​which enable the control and evaluation unit to monitor the behavior of the fluid in the U-tube arrangement and thus to determine an actually generated flow through the at least partially horizontal pipe section and thus through the respective flow meter MUT.

[0052] An exemplary use of the test and / or calibration setup 1 shown is described below.

[0053] To generate a harmonically oscillating motion of the fluid in the U-tube arrangement, the drive periodically exerts a time-dependent pressure on the fluid column, causing the fluid column to move evenly up and down at a specific excitation frequency. This results in a back-and-forth movement of at least a portion of the fluid between the two vertical pipe sections 3 and 5, and thereby through or past the horizontal pipe section 7 and the provided flow meter MUT. A height difference Δh between the fluid columns in the two vertical pipe sections 3 and 5 results in a gravitational restoring force and enables particularly efficient maintenance of the generated harmonic oscillation of the fluid, especially when the selected excitation frequency is close to or equal to the resonant frequency of the fluid's movement through the U-tube arrangement.The buffer tank 9 serves to limit the maximum amplitude of the generated vibration of the fluid and thus to prevent even a partial emptying of the horizontal pipe section 7 of the fluid.

[0054] The control and evaluation unit determines the actually generated flow rate over the entire stroke periods using signals from the provided sensors S, P and ΔP as well as, if applicable, other sensors not shown and / or from control signals to the drive unit 11.

[0055] To test the intended MUT flow meter, this also measures the flow through the horizontal pipe section 7 independently of the actually generated flow determined by the control and evaluation unit. Finally, the determined actual flow is compared with the flow measured by the MUT flow meter, in particular by the control and evaluation unit, in order to evaluate the function of the MUT flow meter.

[0056] In addition or alternatively, the intended flow meter MUT can be calibrated based on the determined actual flow so that the flow meter MUT outputs flow measurement values ​​corresponding to the actual flow.

[0057] This can be done for different excitation frequencies and, when replacing the respective horizontal pipe section 7, for different inner diameters. Consequently, testing and / or calibration is possible for a wide variety of nominal diameters of the horizontal pipe section 7, flow rates, and frequencies.

[0058] Finally, it should be noted that the scope of the following claims is not intended to be limited by the above embodiment, but also includes modifications of the described embodiment.

[0059] For example, the vertical pipe sections 3 and 5 can each be inclined by a certain angle from the vertical, other and / or additional sensors (possibly also in the form of an already calibrated flow meter) can be provided to determine the actual flow and / or differently designed drive units can be provided.

[0060] For example, the drive can be designed as a compressed air cushion, peristaltic or magnetic (ferrofluid) to set the fluid column in motion. List of reference symbols

[0061] 1Test and / or calibration setup 3(left) vertical pipe section 5(right) vertical pipe section 7horizontal pipe section 9Buffer tank 11Drive unit ΔhHeight difference MUT"Meter-Under-Test" / Flowmeter PAbsolute pressure sensor ΔPDifference pressure sensor SLevel sensor

Claims

1. A test and / or calibration assembly (1) for flowmeters (MUT), in particular for ultrasonic flowmeters, wherein the test and / or calibration assembly (1) comprises: a U-pipe arrangement having two at least proportionally vertical pipe sections (3, 5) and one at least proportionally horizontal pipe section (7) which connects the two at least proportionally vertical pipe sections (3, 5) to one another, in particular in their lower region; a fluid which fills the at least proportionally horizontal pipe section (7) and projects into the two at least proportionally vertical pipe sections (3, 5) to form fluid columns there; a drive unit (11) which is configured to move the fluid along the U-pipe arrangement so that a volume flow of fluid through the at least proportionally horizontal pipe section (7) and, at the same time, a variation in the height of the two fluid columns in the two at least proportionally vertical pipe sections (3, 5) take place; and a control and evaluation unit which is configured to control the drive unit (11) and to monitor the behavior of the fluid in order to determine an actually generated flow through the at least proportionally horizontal pipe section (7) therefrom; wherein the at least proportionally horizontal pipe section (7) has a test and / or calibration region in which the flowmeter (MUT) to be tested and / or calibrated can be provided to measure a flow through the at least proportionally horizontal pipe section (7), wherein the control and evaluation unit can be coupled to the respective flowmeter (MUT) to be tested and / or calibrated and is configured to compare the flow measured by the flowmeter (MUT) with the actually generated flow and to output a corresponding result and / or to calibrate, in particular automatically, the flowmeter (MUT) based on the actually generated flow, characterized in that the drive unit (11) and the control and evaluation unit are configured to effect an oscillating variation, in particular a harmonically oscillating variation, in the height of the fluid columns in the two at least proportionally vertical pipe sections (3, 5) and thus a correspondingly oscillating flow through the at least proportionally horizontal pipe section (7).

2. A test and / or calibration assembly (1) according to claim 1, wherein the control and evaluation unit is configured to monitor and evaluate the behavior of the fluid over at least half a stroke period, in particular over a plurality of - preferably consecutive - stroke periods.

3. A test and / or calibration assembly (1) according to claim 1 or 2, wherein the drive unit (11) and the control and evaluation unit are configured to effect the oscillating variation in the height of the fluid columns in the two at least proportionally vertical pipe sections (3, 5) and thus a correspondingly oscillating flow through the at least proportionally horizontal pipe section (7) at a predetermined, in particular settable, excitation frequency.

4. A test and / or calibration assembly (1) according to claim 3, wherein the drive unit (11) and the control and evaluation unit are configured to effect the oscillating variation in the height of the fluid columns in the two at least proportionally vertical pipe sections (3, 5) and thus a correspondingly oscillating flow through the at least proportionally horizontal pipe section (7) at the resonant frequency of this movement.

5. A test and / or calibration assembly (1) according to any one of the preceding claims, wherein the control and evaluation unit for monitoring the behavior of the fluid is coupled to at least one intrinsic sensor (P, ΔP) which determines intrinsic properties of the fluid in the U-pipe arrangement, wherein the at least one intrinsic sensor (P, ΔP) is in particular configured to continuously determine a static pressure of the fluid in a predetermined region of the U-pipe arrangement and / or a differential pressure of the fluid between two different regions of the U-pipe arrangement.

6. A test and / or calibration assembly (1) according to any one of the preceding claims, wherein the control and evaluation unit for monitoring the behavior of the fluid is coupled to at least one extrinsic sensor (S) which determines extrinsic properties of the fluid in the U-pipe arrangement, wherein the at least one extrinsic sensor (S) is in particular configured to continuously determine the height of the fluid column in at least one of the two at least proportionally vertical pipe sections (3, 5) and / or a position of the drive unit (11).

7. A test and / or calibration assembly (1) according to any one of the preceding claims, wherein the drive unit (11) comprises at least one displacement apparatus which is configured to displace the fluid in at least one of the two at least proportionally vertical pipe sections (3, 5) in order to move the fluid along the U-pipe arrangement.

8. A test and / or calibration assembly (1) according to claim 7, wherein the displacement apparatus is designed in the form of a hydraulic or pneumatic displacement apparatus, in particular having a displacement piston movable along the respective at least proportionally vertical pipe section.

9. A test and / or calibration assembly (1) according to one of the claims 7 and 8, wherein the drive unit (11) comprises at least one separate displacement apparatus for each of the two at least proportionally vertical pipe sections (3, 5).

10. A test and / or calibration assembly (1) according to any one of the preceding claims, wherein the fluid is a liquid which is in particular largely incompressible, wherein the fluid is in particular water.

11. A test and / or calibration assembly (1) according to any one of the preceding claims, wherein the test and / or calibration assembly (1) is configured as a stationary test stand, wherein the nominal width of the at least proportionally horizontal pipe section is in particular in a range from 500 mm to 3000 mm, wherein the test and / or calibration assembly (1) is in particular configured to generate a flow rate of up to 30,000 m3 / h, wherein the two at least proportionally vertical pipe sections (3, 5) each have a height of 20 to 40 meters.

12. A test and / or calibration assembly (1) according to any one of the preceding claims, wherein the test and / or calibration assembly (1) is configured such that the substantially horizontal pipe section (7) is completely filled with the fluid in every permitted operating state.

13. A test and / or calibration assembly (1) according to any one of the preceding claims, wherein the test and / or calibration assembly (1) is configured to perform the testing and / or calibration of the respective flowmeter (MUT) over a plurality of movement sequences of the fluid through the at least proportionally horizontal pipe section (7), in particular at a predetermined excitation frequency.

14. A method for testing and / or calibrating a flowmeter (MUT), in particular using a test and / or calibration assembly (1) according to any one of the preceding claims, wherein the method comprises the following steps: generating a harmonically oscillating movement of a fluid through an at least proportionally vertically oriented U-pipe arrangement having an at least proportionally horizontal pipe section (7) and two at least proportionally vertical pipe sections (3, 5); determining the actual flow through the at least proportionally horizontal pipe section (7) that is generated in this respect; comparing the determined actual flow with the flow measured by a flowmeter (MUT) provided at the at least proportionally horizontal pipe section (7) and / or calibrating a flowmeter (MUT) provided at the at least proportionally horizontal pipe section (7) based on the determined actual flow.