Method for calibrating a measuring system and calibration device

Abstract

Method for calibrating a measuring system (8), which serves to determine a property of a first medium and / or a second medium, comprehensive the steps - Directing the first medium, the second medium or a mixture of the first and the second medium to a flow meter (5), - Determining the flow rate of the medium using the flow meter (5), - Directing the medium to the measuring system (8), - Determining the property of the medium by the measuring system (8), and - Calibrating the measuring system (8) using the measurement data from the flow meter (5), characterized by that the procedure continues to include the following steps: - Heating / cooling the medium to a specific temperature, - Determining the temperature of the medium, and - Determining the temperature coefficient of the medium.

Description

[0001] The invention relates to a method for calibrating a measuring system with the features of the preamble of the first claim. The invention further relates to a calibration device.

[0002] A generic process is disclosed in US 5 072 416 A.

[0003] The problem will first be explained using the property of "mixing ratio." In many applications, it is important to know the precise mixing ratio of two media. For example, in oil production, it is crucial to know the oil-to-water ratio. This is necessary for accounting purposes, as it determines levies such as taxes. Simultaneously, the mixing ratio is a measure of the quality of the oil well.

[0004] Viscosity is a key parameter in rheology. It is important in virtually all areas where fluids are used or occur. Viscosity is a particularly important characteristic in oil production.

[0005] To calibrate measuring instruments for determining mixing ratios or viscosity, samples of the medium whose mixing ratio / viscosity was to be determined were previously taken and analyzed in the laboratory. If differences arose between the measured value "on-site" and the measured value in the laboratory, the measuring instrument was calibrated and / or adjusted accordingly on-site. However, inaccuracies arise due to the time lag. Furthermore, by definition, different conditions prevail in the laboratory (temperature, air pressure, humidity, etc.), so inaccuracies occur simply due to the change of location.

[0006] Procedures for calibration are disclosed not only in the aforementioned US 5 072 416 A, but also in US 6 032 539 A or US 6 234 030 B1.

[0007] The invention is based on the objective of enabling a precise determination of a property, in particular the mixing ratio of two media and / or the viscosity of a medium, directly at the site of the process.

[0008] The problem is solved by a method having the features of the first claim.

[0009] It is therefore possible to perform the calibration of the measuring device directly on site under the prevailing environmental conditions.

[0010] In an advantageous embodiment, the property is the mixing ratio, and the second medium is in particular oil.

[0011] Alternatively or additionally, the property in question is viscosity, and the second medium is specifically glycerin.

[0012] In an advantageous embodiment, the flow rate is determined using a mass flow meter. A mass flow meter can also be used to determine the density of the medium being measured. If the media comprising the mixture have different densities, the mixing ratio can thus be precisely determined. Advantageously, the two media are measured beforehand in their pure form, i.e., the densities of the pure media are determined. Determining the viscosity of a medium also requires knowing the mass flow rate or mass acceleration.

[0013] According to the invention, the method further comprises the steps: heating / cooling at least the medium to a specific temperature; determining the temperature of the medium; and determining the temperature coefficient of the medium.

[0014] Since the density of a medium is temperature-dependent, the temperature coefficient can be determined. This provides precise knowledge of the density at a specific temperature.

[0015] The problem is further solved by a calibration device, in particular a portable calibration device, comprising: a first container with a first medium, in particular water; a second container with a second medium; a first flow meter with an inlet and an outlet, wherein the first container is connected to the inlet of the first flow meter, and wherein the second container is connected to the inlet of the first flow meter; a third container with a third medium, wherein the third medium is a mixture of the first medium and the second medium, and wherein the third container is connected to the inlet of the first flow meter; a first connecting section, in particular with a second flow meter, which connects the first container to the third container;a second connecting section, in particular with a third flow meter, which connects the second container to the third container, wherein the output of the first flow meter can be connected to an input of the measuring system; and a data processing unit that controls and / or regulates the inflow from the first container to the first flow meter and to the third container, that controls and / or regulates the inflow from the second container to the first flow meter and to the third container, that controls and / or regulates the inflow from the third container to the first flow meter, wherein the inflow to the first flow meter and thus to the measuring system takes place either with medium from the first container or from the second container or from the third container.

[0016] It is therefore possible to calibrate the measuring device directly on-site under the prevailing environmental conditions by connecting the calibration device to the inlet of the measuring device and supplying the first, second, or third medium to the measuring device. The measuring device then determines the mixing ratio in the supplied medium.

[0017] By comparing the measurement data of the first flow meter with the measurement data of the measuring device, the first measuring device can be calibrated and / or adjusted, e.g. by the data processing unit.

[0018] Preferably, the property is the mixing ratio, and the second medium is in particular oil.

[0019] Alternatively or additionally, the property in question is viscosity, and the second medium is specifically glycerin.

[0020] In an advantageous embodiment, the calibration device further comprises a fourth container with a fourth medium, in particular calibration oil, wherein the fourth container is connected to the inlet of the first flow meter. It is thus possible to calibrate and, if necessary, adjust the first flow meter itself, which functions as a reference flow meter.

[0021] In an advantageous embodiment, at least the first flow meter is a mass flow meter. A mass flow meter can also be used to determine the density of the medium being measured. If the media making up the mixture have different densities, the mixing ratio can thus be determined precisely. Advantageously, the two media are measured beforehand in their pure form, i.e., the densities of the pure media are determined.

[0022] In an advantageous embodiment, at least one of the containers contains a heating / cooling element and a temperature sensor.

[0023] In a preferred advanced version, the data processing unit uses the measurement data from the mass flow meter and the temperature sensor to determine the temperature coefficient of the medium in the first, second, third, and / or fourth container. Since the density of a medium is temperature-dependent, the temperature coefficient can thus be determined. This provides precise knowledge of the density at a specific temperature.

[0024] In an advantageous embodiment, the data processing unit is designed such that any desired mixture of the first medium from the first container and the second medium from the second container can be set in the third container. Thus, any desired mixing ratio of the first and second media can be produced for calibration purposes. Advantageously, the ratio set corresponds to the mixing ratio of the medium that the measuring device monitors at its point of use during normal operation.

[0025] To detect or prevent impermissible pressures or the formation of unwanted steam, a pressure sensor is installed in at least one of the containers.

[0026] Preferably, the calibration device is designed as a compact, mobile, and optionally portable unit. For larger nominal diameters up to approximately DN15, mobility can be ensured by means of casters or similar devices.

[0027] The invention is explained in more detail with reference to the following figure. It shows Fig. 1 the calibration device according to the invention in a first embodiment, and Fig. 2 the calibration device according to the invention in a second embodiment.

[0028] In the figures, identical features are marked with the same reference symbols.

[0029] The calibration device according to the invention in its entirety has the reference numeral 1.

[0030] Calibration device 1 serves to determine a property of a first and / or a second medium. In the following and in Fig. Figure 1 will first address the property "mixing ratio". Later, and in Fig. Figure 2 shows the property "viscosity".

[0031] The measuring system 8 to be calibrated is in Fig. Figure 1 on the left shows a measuring device commonly used in this field to determine the mixing ratio of two media. Measuring system 8, for example, determines the water content of water in oil. This measuring system can then be used, for instance, at an oil well.

[0032] The calibration device 1 consists of a first container 2, a second container 3, and a third container 4. The first container 2 contains a first medium, e.g., oil, in particular pure oil. The second container 3 contains a second medium, e.g., water, in particular pure water. The prefix "pure" here indicates that it is not a mixture, but rather that the oil or water is contaminated with as few impurities and / or mixtures as possible.

[0033] The calibration device 1 is designed as a portable, even mobile, unit. For this purpose, the calibration device 1 is equipped with casters or similar features. Nominal diameters of up to DN15 are thus possible. The calibration device 1 is therefore attached directly to the measuring system 8, for example, to an oil well. The oil or water in the first or second container 3, 4 therefore also come directly from the oil well in order to make the calibration as accurate as possible under the conditions prevailing directly at the measuring point.

[0034] The third container 4 contains a mixture of the first and second media, namely oil and water. Pipes run from the first container 2 to the third container 4 and from the second container 3 to the third container 4. Pumps 15 and valves 14 are located at the appropriate points.

[0035] To ensure precise adjustment of the mixing ratio in the third container 4, a second flow meter 6 and a third flow meter 7 are provided. The second flow meter 6 connects the first to the third container 1, 3; the third flow meter 7 connects the second container 3 to the third container 4.

[0036] From the first, second, and third containers 2, 3, 4, lines run to the measuring system 8. From the measuring system 8, lines run back to the first, second, and third containers 2, 3, 4 (shown via connections 9, 10, 11). Pumps 15 and valves 14 are provided at the corresponding locations.

[0037] The flow direction of the respective media is indicated by an arrow 16.

[0038] In the direction of flow upstream of the measuring system 8, a first flow meter 5 is provided, i.e., regardless of where the medium flows from - first, second or third container 2, 3, 4 - the flow meter 5 can detect this flow.

[0039] At least the first flow meter 5 is designed as a mass flow meter. Mass flow meters are capable of determining not only the mass flow but also the density and thus also the viscosity (see below).

[0040] In a first step, the medium is transferred from the first container 2 to the measuring system 8, or through the first flow meter 5, and its density is determined. In a next step, the medium is transferred from the second container 3 to the measuring system 8, or through the first flow meter 5, and its density is determined. This allows the densities of the pure media, i.e., pure water and pure oil, to be determined directly on-site under the prevailing conditions. This yields a 0% and a 100% value for the mixing ratio. After passing through the measuring system, the media are either returned to their respective containers 2 and 3, disposed of properly, and / or transferred to the third container 4. Advantageously, the media are transferred in such a way that they do not contaminate each other.

[0041] In a further step, a mixture of pure oil and pure water from the first and second containers 2, 3 is prepared in the third container. As already mentioned, the respective flow rates are measured by the second and third flow meters 6, 7 and controlled via the corresponding valves 14 and pumps 15. Any desired mixing ratio can be produced. Advantageously, a ratio can be set that corresponds to the mixing ratio of the medium that the measuring device monitors at its point of use during normal operation.

[0042] Control is handled either by a higher-level unit, such as a control center, or – which is more practical for mobile devices – by a data processing unit 17 in the form of a controller, computer, etc. In Fig. Figure 1 shows the data processing unit 17 with the respective dashed control lines for the corresponding components.

[0043] The mixture produced in the third container 4, i.e., the third medium, is now fed to the measuring system 8 or the first flow meter 5. This determines the density of the third medium. From the known densities of the first and second media (measured in the previous step), the mixing ratio, in this specific case the ratio of water to oil, can be calculated from the density of the third medium. The third medium is then either disposed of properly and / or returned to the third container 4.

[0044] If the measurement of the mixing ratio by the measuring system 8 deviates from the measurement by the first flow meter 5 in one of the three cases (medium from first, second or third container 2, 3, 4), the measuring system is (re-)adjusted.

[0045] In the first, second, or third container 2, 3, 4, at least one temperature measurement device 12, consisting of a temperature sensor 12a, a heating / cooling element 12b, and a mixer 12c, is provided. The temperature measurement device 12 allows a specific temperature of the respective medium to be set and monitored. This is crucial because the density of a medium is temperature-dependent, and the temperature coefficient can be determined using the described arrangement. Here, the temperature coefficient is understood to be the relative change in density as a function of the change in temperature relative to a defined reference temperature, such as 20 °C. In contrast to the prior art, i.e., laboratory measurements, the temperature coefficient is determined directly on-site and not assumed from tabulated values, which often do not reflect reality.

[0046] Furthermore, at least one pressure sensor 13 is provided. This allows vapors and pressures generated by heating to be detected and avoided.

[0047] Fig. Figure 2 shows a second embodiment, whereby the above-described principle also applies analogously to the Fig. 2 applies.

[0048] The embodiment in Fig. 2 serves to calibrate the calibration device 1 with respect to the parameter viscosity. To calibrate the first flow meter 5, i.e., the reference device, beforehand, a fourth container 18 with a fourth medium is provided. The fourth medium is, for example, calibration oil. The calibration oil has a known viscosity at a specific temperature. Thus, the first flow meter 5 can be calibrated and, if necessary, adjusted.

[0049] The second container 3 contains, instead of oil as in the exemplary embodiment in Fig. Figure 1 shows glycerin. All media used are therefore inexpensive and non-toxic. Glycerin has a known viscosity.

[0050] Any desired mixing ratio can be set in the third container 4. Therefore, any desired viscosity value can also be set. For example, water from the first container 2, then glycerin from the second container 3, and finally any mixture of the two from the third container 4 can be fed to the calibration device 1. The calibration device 1 can then be calibrated and, if necessary, adjusted.

[0051] In the embodiment in Fig. 2. No second or third flow meter 6, 7 is used to measure the flow rate. These can also be used analogously to determine the mixing ratio in Fig. 1 can be omitted.

[0052] The fourth container 18 also contains a temperature measurement device 12, consisting of a temperature sensor 12a, a heating / cooling element 12b, and a mixer 12c. Viscosity is also highly temperature-dependent, so the temperature measurement device 12 allows a specific temperature of the respective medium to be set and monitored. Thus, the temperature coefficient can also be determined here.

[0053] Fig. Figure 2 does not show any pressure sensors 13. However, depending on the embodiment, these can be used. Similarly, they can also be used in the exemplary embodiment in Fig. 1 can be omitted. Reference symbol list 1 Calibration device 2 First container 3 Second container 4 Third container 5 First flow meter 6 Second flow meter 7 Third flow meter 8 Measuring system 9 connection 8 to 2 10 Connection 8 to 3 11 Connection 8 to 4 12 Temperature measurement 12a Temperature sensor 12b Heating / cooling element 12c mixer 13 Pressure measurement 14 valve 15 pump 16 Arrow indicating the direction of flow 17 Data processing unit 18 Fourth container 19 Connection 8 to 18

Claims

[1] Method for calibrating a measuring system (8), which serves to determine a property of a first medium and / or a second medium, comprehensive the steps - Directing the first medium, the second medium or a mixture of the first and the second medium to a flow meter (5), - Determining the flow rate of the medium using the flow meter (5), - Directing the medium to the measuring system (8), - Determining the property of the medium by the measuring system (8), and - Calibrating the measuring system (8) using the measurement data from the flow meter (5), characterized by , that the procedure continues to include the following steps: - Heating / cooling the medium to a specific temperature, - Determining the temperature of the medium, and - Determining the temperature coefficient of the medium. [2] Method according to claim 1, wherein the flow rate is determined using a mass flow meter. [3] Calibration device (1) for calibrating a measuring system (8) which serves to determine a property of a first medium and / or a second medium, comprehensive: - a first container (2) with the first medium, - a second container (3) with the second medium, - a first flow meter (5) with an inlet and an outlet, wherein the first container (2) is connected to the inlet of the first flow meter (5), and wherein the second container (3) is connected to the inlet of the first flow meter (5), - a third container (4) with a third medium, where the third medium is a mixture of the first medium and the second medium, and wherein the third container (4) is connected to the inlet of the first flow meter (5), - a first connecting section which connects the first container (2) with the third container (4), - a second connecting section, which connects the second container (3) to the third container (4), wherein the output of the first flow meter (5) can be connected to an input of the measuring system (8), and - a data processing unit (17), which controls and / or regulates the flow from the first container (2) to the first flow meter (5) and to the third container (4), which controls and / or regulates the flow from the second container (3) to the first flow meter (5) and to the third container (4), and which controls and / or regulates the flow from the third container (4) to the first flow meter (5), wherein the inflow to the first flow meter (5) and thus to the measuring system (8) takes place either with medium from the first container (2) or from the second container (3) or from the third container (4). [4] Calibration device (1) according to claim 3, wherein the calibration device (1) further comprises a fourth container (18) with a fourth medium, and wherein the fourth container (18) is connected to the inlet of the first flow meter (5). [5] Calibration device (1) according to claim 3 or 4, wherein at least the first flow meter (5) is a mass flow meter. [6] Calibration device (1) according to one of claims 3 to 5, wherein at least in one of the containers (2, 3, 4, 18) a heating / cooling element (12b) and a temperature sensor (12a) is installed. [7] Calibration device (1) according to claims 4 and 6, wherein the data processing unit (17) determines the temperature coefficient of the medium in the first container (2), second container (3), third container (4) and / or fourth container (18) based on the measurement data of the flow meter (5) and the temperature sensor (12a). [8] Calibration device (1) according to any one of claims 3 to 7, wherein the data processing unit (17) is designed such that any mixture of the first medium from the first container (2) and the second medium from the second container (3) can be set in the third container (4). [9] Calibration device (1) according to any one of claims 3 to 8, wherein at least one of the containers (2, 3, 4) has a pressure sensor (13) installed. [10] Calibration device (1) according to any one of claims 3 to 9, wherein the calibration device (1) is designed as a compact, mobile and portable unit.

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