Gas-liquid two-phase flow measurement method and device, computer equipment and storage medium

Abstract

The invention relates to the technical field of two-phase flow measurement, in particular to a gas-liquid two-phase flow measurement method and device, computer equipment and a storage medium. The method comprises the following steps: acquiring a measured volume flow rate, a measured mass flow rate and a measured density which are obtained by measuring equipment and correspond to a gas-liquid two-phase flow to be measured; collecting and calculating a first accurate density corresponding to the target liquid, and calculating a second accurate density corresponding to the target gas based on the gas pressure, the gas temperature and the target gas; substituting the measured volume flow, the measured mass flow, the measured density, the first accurate density and the second accurate density into a fitting formula to obtain fitting data; and processing the first accurate density, the second accurate density, the measured volume flow rate, the fitting data and the measured mass flow rate by using a mass separation formula to obtain a target gas mass flow rate and a target liquid mass flow rate corresponding to the target gas and the target liquid respectively, thereby conveniently and accurately determining the mass flow rate of each phase.

Description

Technical Field

[0001] The present invention relates to the technical field of two-phase flow measurement, and in particular to a gas-liquid two-phase flow measurement method, device, computer equipment and storage medium. Background Art

[0002] At present, most fluids in the fields of energy, chemical engineering and life sciences are gas-liquid two-phase flows. Since the flow of gas-liquid two-phase flow is complex and is affected by many factors, it is difficult to measure the mass flow rate of each phase in the gas-liquid two-phase flow. In the natural gas industry, the main methods used to measure the mass flow of gas-liquid two-phase flow include traditional separation methods. Specifically, the gas-liquid two-phase flow is separated into single-phase gas and liquid by a gas-liquid separator, and then measured by a single-phase mass flow meter. This method requires the use of a large gas-liquid separator and the configuration of a corresponding liquid level control system and valve group. The process is complex, the cost is high, and it requires special maintenance, and continuous online measurement cannot be achieved. In addition, there are currently two-phase flow meters that measure the mass flow of each phase. Due to the lack of a reliable measurement principle, the accuracy is poor when used on site.

[0003] How to improve the convenience of measurement and the accuracy of measurement results while reducing the measurement cost of the mass flow rate of each phase in a two-phase flow in an enterprise is an urgent problem to be solved in the existing technology. Summary of the invention

[0004] To solve the problems in the prior art, the embodiments of this specification provide a gas-liquid two-phase flow measurement method, device, computer equipment and storage medium, which achieve separation only by standing still, greatly reducing the measurement cost, and on the basis of reducing the measurement cost, improve the convenience of measurement and the accuracy of measurement results.

[0005] In order to solve the above technical problems, the specific technical solutions of this specification are as follows:

[0006] On the one hand, the embodiments of this specification provide a gas-liquid two-phase flow measurement method, comprising:

[0007] Obtaining a measured volume flow rate, a measured mass flow rate and a measured density corresponding to the gas-liquid two-phase flow to be measured obtained by the measuring device;

[0008] Collecting a target gas and a target liquid from the gas-liquid two-phase flow to be measured, and calculating a first accurate density corresponding to the target liquid, and calculating a second accurate density corresponding to the target gas based on the gas pressure, the gas temperature and the target gas;

[0009] Substituting the measured volume flow rate, the measured mass flow rate, the measured density, the first accurate density and the second accurate density into a fitting formula to obtain fitting data; and

[0010] The first accurate density, the second accurate density, the measured volume flow rate, the fitting data and the measured mass flow rate are processed using a mass separation formula to obtain a target gas mass flow rate corresponding to the target gas and a target liquid mass flow rate corresponding to the target liquid.

[0011] Further, the step of sampling a target liquid from the gas-liquid two-phase flow to be measured and calculating a first accurate density corresponding to the target liquid includes:

[0012] Static separation of the gas-liquid two-phase flow to be measured to obtain the target liquid in the gas-liquid two-phase flow to be measured; and

[0013] The target liquid is processed using a liquid density determination model to obtain the first accurate density corresponding to the target liquid.

[0014] Furthermore, the method of collecting the target gas from the gas-liquid two-phase flow to be measured and calculating a second accurate density corresponding to the target gas based on the gas pressure, the gas temperature and the target gas further includes:

[0015] Static separation of the gas-liquid two-phase flow to be measured, and obtaining the target gas in the gas-liquid two-phase flow to be measured;

[0016] Performing component analysis on the target gas to obtain at least one gas component included in the target gas; and

[0017] The gas pressure, the gas temperature and the gas component are processed using a gas density determination model to obtain the second accurate density corresponding to the target gas.

[0018] Furthermore, the determination process of the fitting formula further includes:

[0019] Determine a plurality of experimental operating conditions, wherein the experimental operating conditions include an experimental liquid density and an experimental liquid mass flow rate corresponding to the liquid used for the experiment, an experimental gas density and an experimental gas mass flow rate corresponding to the gas used for the experiment, and an experimental accurate volume flow rate corresponding to an experimental two-phase flow, wherein the experimental two-phase flow is a fluid after the liquid used for the experiment and the gas used for the experiment are mixed;

[0020] For each of the experimental working conditions, obtaining the experimentally measured mass flow and the experimentally measured density obtained by the measuring device; and

[0021] The experimental liquid density, the experimental liquid mass flow rate, the experimental gas density, the experimental gas mass flow rate, the experimental accurate volume flow rate, the experimental measured mass flow rate and the experimental measured density corresponding to each of the experimental working conditions are fitted to determine the fitting formula.

[0022] Furthermore, the fitting formula further includes:

[0023]

[0024] Wherein, the f(V Ah , ρ Ag , ρ Al , ρ M ) characterizes the fitting formula, the m M Characterize the experimentally measured mass flow rate, the m Al Characterize the experimental liquid mass flow rate, the m Ag Characterize the experimental gas mass flow rate, the V Ah Characterize the experimental accurate volume flow rate, the ρ Ag Characterize the experimental gas density, the ρ Al Characterize the experimental liquid density, the ρ M Characterization The experiments measured density.

[0025] Furthermore, the mass separation formula further includes,

[0026]

[0027] Among them, the m g represents the target gas mass flow rate, V represents the measured volume flow rate, and ρ l represents the first accurate density, the m represents the measured mass flow rate, and the f(V h , ρ g , ρ l , ρ) characterizes the fitting formula for determining the fitting data, the ρ characterizes the measured density, the V h Characterizes the true volume flow rate, the ρ g The second accurate density is characterized, and the true volume flow rate is the same as the measured volume flow rate.

[0028] Furthermore, the mass separation formula further includes,

[0029]

[0030] Among them, the m l represents the target liquid mass flow rate, V represents the measured volume flow rate, and ρ lrepresents the first accurate density, the m represents the measured mass flow rate, and the f(V h , ρ g , ρ l , ρ) characterizes the fitting formula for determining the fitting data, the ρ characterizes the measured density, the V h Characterizes the true volume flow rate, the ρ g The second accurate density is characterized, and the true volume flow rate is the same as the measured volume flow rate.

[0031] On the other hand, the embodiment of the present specification also provides a gas-liquid two-phase flow measurement system, including a two-phase flow calculation device and a measurement device connected to the two-phase flow calculation device, wherein the measurement device includes a volumetric flow meter, a Coriolis mass flow meter, a pressure measurement device, and a temperature measurement device.

[0032] The volumetric flow meter is used to measure the measured volume flow of the gas-liquid two-phase flow to be measured, and send the measured volume flow to the two-phase flow calculation device;

[0033] The Coriolis mass flowmeter is used to measure the measured mass flow and the measured density of the gas-liquid two-phase flow to be measured, and send the measured mass flow and the measured density to the two-phase flow calculation device;

[0034] The pressure measuring device and the temperature measuring device are used to measure the gas pressure and the gas temperature of the target gas in the gas-liquid two-phase flow to be measured, respectively, and send the gas pressure and the gas temperature to the two-phase flow calculation device;

[0035] The two-phase flow device receives the measured volume flow, measured mass flow, measured density, gas pressure and gas temperature; determines a first accurate density corresponding to the target liquid, and calculates a second accurate density corresponding to the target gas based on the gas pressure, the gas temperature and the target gas; substitutes the measured volume flow, the measured mass flow, the measured density, the first accurate density and the second accurate density into a fitting formula to obtain fitting data; and uses a mass separation formula to process the first accurate density, the second accurate density, the measured volume flow, the fitting data and the measured mass flow to obtain a target gas mass flow corresponding to the target gas and a target liquid mass flow corresponding to the target liquid.

[0036] On the other hand, the embodiment of this specification also provides a gas-liquid two-phase flow measurement device, including:

[0037] An acquisition unit, used for acquiring a measured volume flow rate, a measured mass flow rate and a measured density corresponding to the gas-liquid two-phase flow to be measured obtained by the measuring device;

[0038] A collection and calculation unit, used for collecting target gas and target liquid from the gas-liquid two-phase flow to be measured, and calculating a first accurate density corresponding to the target liquid, and calculating a second accurate density corresponding to the target gas based on the gas pressure, gas temperature and the target gas;

[0039] a fitting calculation unit, configured to substitute the measured volume flow, the measured mass flow, the measured density, the first accurate density and the second accurate density into a fitting formula to obtain fitting data; and

[0040] A processing unit is used to process the first accurate density, the second accurate density, the measured volume flow rate, the fitting data and the measured mass flow rate by using a mass separation formula to obtain a target gas mass flow rate corresponding to the target gas and a target liquid mass flow rate corresponding to the target liquid.

[0041] On the other hand, an embodiment of the present specification further provides a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the above method when executing the computer program.

[0042] On the other hand, an embodiment of the present specification further provides a computer-readable storage medium on which computer instructions are stored, and the computer instructions implement the above method when executed by a processor.

[0043] On the other hand, an embodiment of the present specification further provides a computer program product, including a computer program / instruction, and a method implemented when the computer program / instruction is executed by a processor.

[0044] By using the embodiments of this specification, based on the measuring device, the measured volume flow, measured mass flow and measured density of the gas-liquid two-phase flow to be measured are obtained; the target gas and target liquid are collected from the measured gas-liquid two-phase flow, and the first accurate density corresponding to the target liquid is calculated, and the second accurate density corresponding to the target gas is calculated based on the gas pressure, gas temperature and target gas; the measured volume flow, measured mass flow, measured density, first accurate density and second accurate density are substituted into the fitting formula obtained by pre-fitting to obtain fitting data; and the mass separation formula is used to process the first accurate density, the second accurate density, the measured volume flow, the fitting data and the measured mass flow to obtain the target gas mass flow corresponding to the target gas and the target liquid mass flow corresponding to the target liquid. As a result, there is no need to use a huge gas-liquid separator for high-standard separation, and separation can be achieved only by standing, which greatly reduces the measurement cost, and on the basis of reducing the measurement cost, improves the convenience of measurement and the accuracy of the measurement results. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the embodiments of this specification or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this specification. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0046] Figure 1 The figure shows a schematic diagram of a system for implementing a gas-liquid two-phase flow measurement method according to an embodiment of the present specification;

[0047] Figure 2 Shown is a flow chart of a gas-liquid two-phase flow measurement method according to an embodiment of this specification;

[0048] Figure 3 It is a flow chart of a first accurate density determination method according to an embodiment of this specification;

[0049] Figure 4 It is a flow chart of a second accurate density determination method according to an embodiment of this specification;

[0050] Figure 5 Shown is a flow chart of a method for determining a fitting formula according to an embodiment of this specification;

[0051] Figure 6 The figure shows a schematic diagram of a gas-liquid two-phase flow measurement system according to an embodiment of the present specification;

[0052] Figure 7 The figure shows a schematic diagram of the structure of a gas-liquid two-phase flow measurement device according to an embodiment of the present specification;

[0053] Figure 8 This is a schematic diagram of the structure of a computer device according to an embodiment of this specification.

[0054] [Description of Reference Numerals]

[0055] 110. Measuring equipment;

[0056] 120. Two-phase flow calculation equipment;

[0057] 601. Coriolis mass flowmeter;

[0058] 602. Pressure measuring equipment;

[0059] 603. Temperature measuring equipment;

[0060] 604, positive displacement flow meter;

[0061] 710, acquisition unit;

[0062] 720, acquisition and calculation unit;

[0063] 730, fitting calculation unit;

[0064] 740, processing unit;

[0065] 802. Computer equipment;

[0066] 804. Processing equipment;

[0067] 806. Storage resources;

[0068] 808, driving mechanism;

[0069] 810, input / output module;

[0070] 812. Input device;

[0071] 814. Output device;

[0072] 816. Presentation equipment;

[0073] 818. Graphical user interface;

[0074] 820, network interface;

[0075] 822, communication link;

[0076] 824. Communication bus. DETAILED DESCRIPTION

[0077] The following will be combined with the drawings in the embodiments of this specification to clearly and completely describe the technical solutions in the embodiments of this specification. Obviously, the described embodiments are only part of the embodiments of this specification, not all of the embodiments. Based on the embodiments in this specification, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this specification.

[0078] It should be noted that the terms "first", "second", etc. in the description and claims of this specification and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of this specification described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, device, product or equipment that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or equipment.

[0079] It should be noted that the steps shown in the flowcharts of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and that, although a logical order is shown in the flowcharts, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0080] Figure 1 The diagram shows a system diagram of an implementation method of a gas-liquid two-phase flow measurement method according to an embodiment of the present specification, which may include: a measuring device 110 and a two-phase flow calculation device 120, wherein the measuring device 110 and the two-phase flow calculation device 120 communicate with each other through a network. The measuring device 110 may include, for example, a volumetric flowmeter for measuring volume flow, and a Coriolis mass flowmeter for measuring mass flow and density. The measuring device 110 measures the measured volume flow, the measured mass flow, and the measured density from the gas-liquid two-phase flow to be measured, and sends the measured volume flow, the measured mass flow, and the measured density to the two-phase flow calculation device 120. The two-phase flow calculation device 120 collects the target gas and the target liquid from the gas-liquid two-phase flow to be measured, and calculates the first accurate density corresponding to the target liquid, and calculates the second accurate density corresponding to the target gas based on the gas pressure, gas temperature and target gas; substitutes the measured volume flow, measured mass flow, measured density, first accurate density and second accurate density into the fitting formula to obtain fitting data; and uses the mass separation formula to process the first accurate density, the second accurate density, the measured volume flow, the fitting data and the measured mass flow to obtain the target gas mass flow corresponding to the target gas and the target liquid mass flow corresponding to the target liquid. It should be noted that the system may also include a display device, which is communicatively connected to the two-phase flow calculation device 120. After determining the target gas mass flow and the target liquid mass flow, the two-phase flow calculation device 120 may send the target gas mass flow and the target liquid mass flow to the display device for the user to view.

[0081] like Figure 2 The flowchart of a gas-liquid two-phase flow measurement method according to an embodiment of the present specification is shown. The gas-liquid two-phase flow measurement process is described in this figure, but more or fewer operation steps may be included based on conventional or non-creative work. The sequence of steps listed in the embodiment is only one way of executing the steps among many sequences, and does not represent the only execution sequence. When the actual system or device product is executed, it can be executed in the sequence or in parallel according to the method shown in the embodiment or the accompanying drawings. Specifically, Figure 2 As shown, the method may include:

[0082] S210, obtaining a measured volume flow rate, a measured mass flow rate, and a measured density corresponding to the gas-liquid two-phase flow to be measured obtained by a measuring device;

[0083] S220, collecting a target gas and a target liquid from the gas-liquid two-phase flow to be measured, and calculating a first accurate density corresponding to the target liquid, and calculating a second accurate density corresponding to the target gas based on the gas pressure, the gas temperature and the target gas;

[0084] S230, substituting the measured volume flow rate, the measured mass flow rate, the measured density, the first accurate density and the second accurate density into a fitting formula to obtain fitting data;

[0085] S240, using a mass separation formula to process the first accurate density, the second accurate density, the measured volume flow rate, the fitting data and the measured mass flow rate to obtain a target gas mass flow rate corresponding to the target gas and a target liquid mass flow rate corresponding to the target liquid.

[0086] By using the embodiments of this specification, based on the measuring device, the measured volume flow, measured mass flow and measured density of the gas-liquid two-phase flow to be measured are obtained; the target gas and target liquid are collected from the gas-liquid two-phase flow with measurement, and the first accurate density corresponding to the target liquid is calculated, and the second accurate density corresponding to the target gas is calculated based on the gas pressure, gas temperature and target gas; the measured volume flow, measured mass flow, measured density, first accurate density and second accurate density are substituted into the fitting formula obtained by pre-fitting to obtain fitting data; and the mass separation formula is used to process the first accurate density, the second accurate density, the measured volume flow, the fitting data and the measured mass flow to obtain the target gas mass flow corresponding to the target gas and the target liquid mass flow corresponding to the target liquid. As a result, there is no need to use a huge gas-liquid separator for high-standard separation, and separation can be achieved only by standing, which greatly reduces the measurement cost, and on the basis of reducing the measurement cost, improves the convenience of measurement and the accuracy of the measurement results.

[0087] According to one embodiment of the present specification, a measuring device is used to measure a gas-liquid two-phase flow to be measured, and a volume flow rate, a mass flow rate and a density are obtained, and the volume flow rate, the mass flow rate and the density are used as the measured volume flow rate, the measured mass flow rate and the measured density, respectively. The measuring device includes a first measuring device for measuring the volume flow rate, a second measuring device for measuring the mass flow rate and a third measuring device for measuring the density, and at least two of the first measuring device, the second measuring device and the third measuring device can be integrated into one device, or can be separately arranged. For example, the first measuring device can be a volumetric flowmeter, and the second measuring device and the third measuring device are integrated into one device, and the device includes a Coriolis mass flowmeter.

[0088] The gas-liquid two-phase flow to be measured is separated to obtain gas and liquid, and the gas and liquid are used as target gas and target liquid respectively. It should be noted that the separation can be based on a relatively simple separation method, which is only used to measure density, and does not require high-precision separation, thereby greatly reducing the measurement cost. After the gas-liquid two-phase flow to be measured is separated, the pressure and temperature of the target gas are measured to obtain the gas pressure and gas temperature.

[0089] The density of the target liquid is measured to obtain a first accurate density corresponding to the target liquid. Specifically, the density of the target liquid can be measured based on a liquid densitometer. For the target gas, the second accurate density corresponding to the target gas is determined in combination with the measured gas pressure and gas temperature. Since the target gas and the target liquid are measured separately here, the accurate densities corresponding to the target gas and the target liquid are determined to correct the mass flow measured by the measuring device, and then determine the mass flow corresponding to the target gas and the target liquid respectively. The method for measuring the second accurate density is, for example, a gas component analysis method.

[0090] A fitting formula is constructed in advance for the two-phase flow. Specifically, the density and mass flow rate of the liquid and gas used in the experiment are measured; then the liquid and gas used in the experiment are mixed to obtain the experimental two-phase flow, and the volume flow rate of the experimental two-phase flow is measured; the mass flow rate and density of the experimental two-phase flow are measured using a measuring device; based on the multiple data obtained by the measurement, a functional relationship between the results of the mass flow rate measurement of the liquid and gas used in the experiment and the results of the mass flow rate measurement corresponding to the experimental two-phase flow is fitted, and the functional relationship is used as a fitting formula. The variables in the fitting formula include the volume flow rate, the density of the gas, the density of the liquid, and the density of the two-phase flow.

[0091] The measured volume flow rate, the first accurate density, the second accurate density and the measured density are respectively substituted into the fitting formula to obtain fitting data.

[0092] The mass separation formula determined by the theoretical analysis in advance is used to process the first accurate density, the second accurate density, the measured volume flow rate, the fitting data and the measured mass flow rate to obtain the target gas mass flow rate corresponding to the target gas and the target liquid mass flow rate corresponding to the target liquid.

[0093] According to another embodiment of the present specification, the mass separation formula is shown in the following formula (1). The formula (1) is used to determine the target gas mass flow rate corresponding to the target gas.

[0094]

[0095] Among them, m gCharacterizes the target gas mass flow rate, V characterizes the measured volume flow rate, ρ l represents the first accurate density, m represents the measured mass flow, f(V h ,ρ g ,ρ l ,ρ) represents the fitting formula for determining the fitting data, ρ represents the measured density, V h Characterizes the true volume flow rate, ρ g Characterizes the second most accurate density, and the true volume flow is the same as the measured volume flow.

[0096] According to another embodiment of the present specification, the mass separation formula may also be shown as the following formula (2), for example.

[0097] The formula (2) is used to determine the target liquid mass flow rate corresponding to the target liquid.

[0098]

[0099] Among them, m l represents the mass flow rate of the standard liquid, V represents the measured volume flow rate, ρ l represents the first accurate density, m represents the measured mass flow, f(V h ,ρ g ,ρ l ,ρ) represents the fitting formula for determining the fitting data, ρ represents the measured density, V h Characterizes the true volume flow rate, ρ g Characterizes the second most accurate density, and the true volume flow is the same as the measured volume flow.

[0100] It should be noted that, since the present embodiment takes the volume flow meter as an example, the measured volume flow is the accurate volume flow. If the volume flow is measured by other volume flow measuring devices, the measured volume flow needs to be corrected to obtain the real volume flow. Since different volume flow measuring devices can be used, the correction method cannot be unified. Here, an appropriate volume flow correction method can be selected according to the actual situation to correct the volume flow, so as to determine the real volume flow based on the measured volume flow.

[0101] Figure 3 The flowchart of a first accurate density determination method according to an embodiment of the present specification is shown. Figure 3 A process for first accurate density determination is described in , but may include more or fewer steps based on routine or uncreative work. Figure 3 As shown, the method may include:

[0102] S3211, statically separating the gas-liquid two-phase flow to be measured, and obtaining the target liquid in the gas-liquid two-phase flow to be measured;

[0103] S3212, using the liquid density determination model to process the target liquid to obtain a first accurate density corresponding to the target liquid.

[0104] According to another embodiment of the present specification, a static separation method is used to separate the two-phase flow to be measured to obtain a target gas and a target liquid. Specifically, the two-phase flow to be measured is statically layered, and the liquid can be discharged from the valve at the lower end to obtain the target liquid. The target liquid is processed to obtain a density corresponding to the target liquid, and the density is used as the first accurate density.

[0105] Specifically, the method for determining the first accurate density may include a liquid density determination model. The liquid density determination model may be, for example, any liquid density meter, such as a digital electronic density meter, a float type density meter, a static pressure type density meter, a vibration type density meter, and a radioisotope density meter. Specifically, an appropriate liquid density meter may be selected according to actual conditions, and this specification does not limit this.

[0106] Figure 4 The flowchart of a second accurate density determination method according to an embodiment of the present specification is shown. Figure 4 A second accurate density determination process is described in , but may include more or fewer steps based on routine or uncreative work. Figure 4 As shown, the method may include:

[0107] S4221, statically separating the gas-liquid two-phase flow to be measured, and obtaining the target gas in the gas-liquid two-phase flow to be measured;

[0108] S4222, performing component analysis on the target gas to obtain at least one gas component included in the target gas;

[0109] S4223, using a gas density determination model to process the gas pressure, gas temperature and gas composition to obtain a second accurate density corresponding to the target gas.

[0110] According to another embodiment of the present specification, a two-phase flow to be measured is subjected to static stratification to obtain a gas located at an upper portion, and the gas is used as a target gas.

[0111] The target gas is analyzed by an off-line chromatograph to obtain all gas components in the target gas, that is, a mixture of gases that the target gas is.

[0112] Then, based on the gas density determination model, the gas pressure and gas temperature obtained by measuring the target gas are processed for the gas components to obtain a second accurate density corresponding to the target gas. The gas density determination model can be, for example, a physical property value calculation model. Specifically, the second accurate density is determined based on an ideal gas state equation. For example, the second accurate density of the target gas can also be determined based on other methods, which is not limited in this specification.

[0113] Figure 5 The flowchart of a method for determining a fitting formula according to an embodiment of the present specification is shown. The process of determining the fitting formula is described in this figure, but more or fewer operation steps may be included based on conventional or non-creative labor. Figure 5 As shown, the method may include:

[0114] S531, determining multiple experimental conditions;

[0115] S532, for each experimental working condition, obtaining an experimentally measured mass flow rate and an experimentally measured density obtained by a measuring device;

[0116] S533, fitting the experimental liquid density, experimental liquid mass flow rate, experimental gas density, experimental gas mass flow rate, experimental accurate volume flow rate, experimental measured mass flow rate and experimental measured density corresponding to each experimental working condition to determine a fitting formula.

[0117] According to another embodiment of the present specification, the experimental working conditions include the experimental liquid density and the experimental liquid mass flow rate corresponding to the liquid used for the experiment, the experimental gas density and the experimental gas mass flow rate corresponding to the gas used for the experiment, and the experimental accurate volume flow rate corresponding to the experimental two-phase flow, and the experimental two-phase flow is the fluid after the liquid used for the experiment and the gas used for the experiment are mixed. In addition, it should be noted that the working conditions here may also include, for example, the gas-liquid ratio when mixed into the experimental two-phase flow. Adaptively, when the working conditions include the gas-liquid ratio, it is also necessary to determine the enterprise ratio between the target gas and the target liquid for the gas-liquid two-phase flow to be measured, so as to adapt to the fitting formula and determine accurate fitting data.

[0118] For the experimental two-phase flow obtained under each test condition, mass flow measurement and density measurement are performed using measuring equipment to obtain the experimental measured mass flow and experimental measured density corresponding to the experimental appearance flow.

[0119] Based on the multiple data obtained by measurement, the functional relationship between the results of the liquid and gas mass flow measurement (experimental liquid mass flow and experimental gas mass flow) used for the experiment and the results of the mass flow measurement (experimental measured mass flow) corresponding to the experimental two-phase flow is fitted, and the functional relationship is used as a fitting formula. Specific fitting methods may include, for example, multi-parameter fitting regression method and neural network intelligent modeling method.

[0120] According to another embodiment of the present specification, the fitting formula is as shown in the following formula (3).

[0121]

[0122] Among them, f(V Ah ,ρ Ag ,ρ Al ,ρ M ) represents the fitting formula, m M Characterization experiment measured mass flow rate, m Al Characterization of experimental liquid mass flow rate, m Ag Characterization of experimental gas mass flow rate, V Ah Characterize the experimental accurate volume flow rate, ρ Ag Characterize the experimental gas density, ρ Al Characterize the experimental liquid density, ρ M Characterization experiments measure density.

[0123] Figure 6 Shown is a schematic diagram of a gas-liquid two-phase flow measurement system according to an embodiment of the present specification.

[0124] According to another embodiment of the present specification, a gas-liquid two-phase flow measurement system includes a phase flow calculation device and a measurement device. Specifically, the measurement device includes a Coriolis mass flowmeter 601, a pressure measurement device 602, a temperature measurement device 603 and a volumetric flowmeter 604 arranged in sequence.

[0125] The volumetric flowmeter 604 is used to measure the measured volume flow of the gas-liquid two-phase flow to be measured, and send the measured volume flow to the two-phase flow calculation device; the Coriolis mass flowmeter 601 is used to measure the measured mass flow and measured density of the gas-liquid two-phase flow to be measured, and send the measured mass flow and measured density to the two-phase flow calculation device; the pressure measuring device 602 and the temperature measuring device 603 are respectively used to measure the gas pressure and gas temperature of the target gas in the gas-liquid two-phase flow to be measured, and send the gas pressure and gas temperature to the two-phase flow calculation device.

[0126] The two-phase flow calculation device determines a first accurate density corresponding to the target liquid when receiving the measured volume flow, the measured mass flow, the measured density, the gas pressure and the gas temperature, and calculates a second accurate density corresponding to the target gas based on the gas pressure, the gas temperature and the target gas; substitutes the measured volume flow, the measured mass flow, the measured density, the first accurate density and the second accurate density into a fitting formula to obtain fitting data; and uses a mass separation formula to process the first accurate density, the second accurate density, the measured volume flow, the fitting data and the measured mass flow to obtain a target gas mass flow corresponding to the target gas and a target liquid mass flow corresponding to the target liquid.

[0127] Specifically, the measurement principle of the volumetric flowmeter 604 is a fixed displacement method, which uses a mechanical measuring element to continuously divide the fluid into a single known volume, and repeatedly fills and discharges the fluid in the volume to cumulatively measure the fluid flow. Its measurement principle is not affected by the measured medium, and both gas and liquid can be measured by the volumetric flowmeter. Therefore, the volumetric flowmeter can accurately measure the total volume of the gas and liquid phases. The volumetric flowmeter 604 can be a Roots flowmeter, a rotary flowmeter, a scraper flowmeter, a reciprocating piston flowmeter, etc.

[0128] Therefore, the following equation (4) can be implemented based on the volumetric flow meter 604.

[0129] V=V h =V l +V g Formula (4)

[0130] Where V represents the measured volume flow, V h Characterizes the true volume flow rate, V l Characterize liquid volume flow rate and V g Characterizes gas volume flow rate.

[0131] The measurement principle of the Coriolis mass flowmeter 601 is that for single-phase fluid, the Coriolis mass flowmeter can accurately measure the mass flow rate and density of the single-phase medium fluid. The principle of the Coriolis mass flowmeter to measure fluid density is based on the resonance tube principle, and the principle of measuring fluid mass flow is based on the Coriolis effect. The principles of measuring fluid density and mass flow are independent and unrelated. According to theoretical analysis and experimental research, when a gas-liquid two-phase flow flows through the Coriolis mass flowmeter, the output value of the mass flow measurement part and the output value of the density measurement part of the Coriolis mass flowmeter will be significantly offset compared to when a single-phase gas or single-phase liquid flows through. At this time, the mass flow output value of the Coriolis mass flowmeter is greater than the individual gas phase mass flow rate or liquid phase mass flow rate in the gas-liquid two-phase flow, and less than the total mass flow rate of the gas-liquid two-phase fluid. The density measurement output value of the Coriolis mass flowmeter is between the gas phase fluid density and the liquid phase fluid density.

[0132] Therefore, the following inequalities (5) to (7) can be realized based on the Coriolis mass flowmeter 601 .

[0133] m l ≤m≤m l +m g Formula (5)

[0134] m g ≤m≤m l +m g Formula (6)

[0135] ρ g ≤ρ≤ρ l Formula (7)

[0136] Among them, m l Characterize the target liquid mass flow rate, m g represents the target gas mass flow rate, m represents the measured mass flow rate, ρ l Characterizing the first accurate density, ρ g represents the second accurate density, and ρ represents the measured density.

[0137] Through experimental analysis, the deviation between the mass flow measurement output value of the Coriolis mass flowmeter 601 when measuring gas-liquid two-phase flow and the total mass flow rate of the gas-liquid two-phase flow is related to the gas phase flow rate, gas-liquid density ratio (operating pressure) and liquid phase content (liquid-gas ratio), and is expressed as a functional relationship of these parameters. The density measurement output value of the Coriolis mass flowmeter 601 when measuring gas-liquid two-phase flow is related to the gas-liquid density ratio (operating pressure), gas phase flow rate and liquid phase content (liquid-gas ratio). The specific functional relationship is shown in the following formulas (8) to (9).

[0138]

[0139]

[0140] Among them, k represents the deviation correction coefficient function, m l Characterize the target liquid mass flow rate, m g represents the target gas mass flow rate, m represents the measured mass flow rate, ρ l Characterizing the first accurate density, ρ g represents the second most accurate density, ρ represents the measured density, f (1) Characterize the mass flow function, f (2) Characterize the density function.

[0141] For a gas-liquid two-phase flow in a pipeline, the gas phase mass flow rate in the pipeline is m g , gas phase density (second most accurate density) ρ g , liquid phase density (first accurate density) ρ l , and the total volume flow rate V of the gas-liquid two phases h , as shown in the following formula (10).

[0142]

[0143] Among them, V h Characterizes the true volume flow rate, V l Characterizes the liquid volume flow rate, V g Characteristic gas volume flow rate, m l Characterize the target liquid mass flow rate, m g Characterize the target gas mass flow rate, ρ l Characterize the first accurate density, and ρ g Characterizes the second accurate density.

[0144] After separating the target gas and the target liquid and determining the values ​​corresponding to the first accurate density and the second accurate density, the true volume flow rate V of the gas-liquid two-phase flow is h is the target gas mass flow rate m g and liquid-gas ratio (m g / m l ), so formula (8) can be transformed to obtain the following formula (11).

[0145]

[0146] Among them, k represents the deviation correction coefficient function, m l Characterize the target liquid mass flow rate, m g Characterize the target gas mass flow rate, V h is the target gas mass flow rate, ρ l Characterizing the first accurate density, ρ gCharacterize the second most accurate density, f (3) Characterize the first transfer function.

[0147] Similarly, using formula (10) to transform formula (9), we get the following formula (12).

[0148]

[0149] Among them, m l Characterize the target liquid mass flow rate, m g Characterize the target gas mass flow rate, V h is the target gas mass flow rate, ρ l Characterizing the first accurate density, ρ g represents the second most accurate density, ρ represents the measured density, and f (4) Characterize the first transfer function.

[0150] Combining formula (11) and formula (12), we get the following formula (13).

[0151]

[0152] Among them, k represents the deviation correction coefficient function, m l Characterize the target liquid mass flow rate, m g Characterize the target gas mass flow rate, V h is the target gas mass flow rate, ρ l Characterizing the first accurate density, ρ g represents the second accurate density, ρ represents the measured density, and f represents the fitting formula.

[0153] Based on the above analysis and arrangement, it can be obtained that when the Coriolis mass flowmeter measures the two-phase total mass flow of a two-phase flow, the two-phase total mass flow deviation correction coefficient k is expressed as a multivariate function (fitting formula) of the total volume flow of the gas and liquid phases, the gas phase density (the second accurate density), the liquid phase density (the first accurate density), and the measured density. Specifically, using multiple experimental conditions such as Figure 5 The method shown in the figure is used to fit the fitting formula shown in formula (3). In actual gas-liquid two-phase flow measurement, the measured volume flow rate, the measured mass flow rate, the measured density, the first accurate density and the second accurate density are substituted into the fitting formula to obtain specific fitting data.

[0154] Specifically, the density, volume flow rate and mass flow rate of the target gas and the target liquid are all related as shown in the following formulas (14) and (15). Therefore, formula (13) can be processed to obtain the following formulas (16) to (17).

[0155]

[0156]

[0157]

[0158] m l +m g = k·m = f(V h ,ρ g ,ρ l ,ρ) Formula (17)

[0159] Among them, m g Characterizes the target gas mass flow rate, V characterizes the measured volume flow rate, ρ l represents the first accurate density, m represents the measured mass flow, f(V h ,ρ g ,ρ l ,ρ) represents the fitting formula for determining the fitting data, ρ represents the measured density, and the V h Characterizes the true volume flow rate, the ρ g Characterizes the second accurate density.

[0160] The combined solution of formula (16) and formula (17) can yield the mass separation formulas of formula (1) and formula (2).

[0161] Therefore, the theoretical rationality of the mass separation formula used to calculate the target gas mass flow rate and the target liquid mass flow rate is proved.

[0162] In addition, it should be noted that in order to further improve the accuracy of the gas-liquid two-phase flow measurement, a sand removal filter can be provided in front of the Coriolis mass flowmeter 601 to improve the purity of the gas-liquid two-phase flow to be measured.

[0163] Based on the above analysis, it can be seen that the combination of a volumetric flowmeter and a Coriolis mass flowmeter can effectively achieve the determination of the gas phase mass flow rate and the liquid phase mass flow rate in the gas-liquid two-phase flow by measuring the mass flow rate and the volume flow rate of the gas-liquid two-phase flow. And from the above analysis, it can be seen that the mass flow output value and the density measurement output value of the Coriolis mass flowmeter in the two-phase flow measurement have the relationship of equations (5) to (7), that is, the output value of the measurement result when the Coriolis mass flowmeter measures the gas-liquid two-phase flow is bounded, and there will be no divergent results. And through the current relevant experimental research, under extreme working conditions, the maximum deviation between the mass flow output value of the Coriolis mass flowmeter in the gas-liquid two-phase flow measurement and the true total mass of the gas-liquid two-phase flow is 20% to 30%. It is relatively easy to correct this deviation through this system, and the correction error of this system can be controlled within ±5%. Therefore, the use of this system to determine the gas phase mass flow rate and the liquid phase mass flow rate of the gas-liquid two-phase flow can achieve a higher accuracy, which has obvious advantages compared with other existing gas-liquid two-phase flow determination schemes.

[0164] Figure 7 The structure diagram of a gas-liquid two-phase flow measurement device according to an embodiment of the present specification is shown in FIG7 . As shown in FIG7 , it includes:

[0165] An acquisition unit 710 is used to acquire a measured volume flow rate, a measured mass flow rate and a measured density corresponding to the gas-liquid two-phase flow to be measured obtained by a measuring device;

[0166] The acquisition and calculation unit 720 is used to acquire the target gas and the target liquid from the gas-liquid two-phase flow to be measured, and calculate the first accurate density corresponding to the target liquid, and calculate the second accurate density corresponding to the target gas based on the gas pressure, the gas temperature and the target gas;

[0167] A fitting calculation unit 730, for substituting the measured volume flow, the measured mass flow, the measured density, the first accurate density and the second accurate density into a fitting formula to obtain fitting data; and

[0168] The processing unit 740 is used to process the first accurate density, the second accurate density, the measured volume flow rate, the fitting data and the measured mass flow rate using the mass separation formula to obtain the target gas mass flow rate corresponding to the target gas and the target liquid mass flow rate corresponding to the target liquid.

[0169] Since the principle of solving the problem by the above device is similar to that of the above method, the implementation of the above device can refer to the implementation of the above method, and the repeated parts will not be repeated.

[0170] like Figure 8The structure diagram of a computer device in an embodiment of the present specification is shown. The apparatus in the present specification can be a computer device in the present embodiment, and the method of the present specification is executed. The computer device 802 may include one or more processing devices 804, such as one or more central processing units (CPUs), and each processing unit may implement one or more hardware threads. The computer device 802 may also include any storage resource 806, which is used to store any kind of information such as code, settings, data, etc. Non-limiting, for example, the storage resource 806 may include any one or more combinations of the following: any type of RAM, any type of ROM, flash memory device, hard disk, optical disk, etc. More generally, any storage resource can use any technology to store information. Further, any storage resource can provide volatile or non-volatile retention of information. Further, any storage resource can represent a fixed or removable component of the computer device 802. In one case, when the processing device 804 executes an associated instruction stored in any storage resource or a combination of storage resources, the computer device 802 can perform any operation of the associated instruction. The computer device 802 also includes one or more drive mechanisms 808 for interacting with any storage resources, such as a hard disk drive mechanism, an optical disk drive mechanism, and the like.

[0171] The computer device 802 may also include an input / output module 810 (I / O) for receiving various inputs (via input devices 812) and for providing various outputs (via output devices 814). A specific output mechanism may include a presentation device 816 and an associated graphical user interface (GUI) 818. In other embodiments, the input / output module 810 (I / O), the input device 812, and the output device 814 may not be included, and the computer device 802 may be used as a computer device in a network. The computer device 802 may also include one or more network interfaces 820 for exchanging data with other devices via one or more communication links 822. One or more communication buses 824 couple the components described above together.

[0172] The communication link 822 may be implemented in any manner, for example, through a local area network, a wide area network (e.g., the Internet), a point-to-point connection, etc., or any combination thereof. The communication link 822 may include any combination of hardwired links, wireless links, routers, gateway functions, name servers, etc. governed by any protocol or combination of protocols.

[0173] The embodiments of the present specification also provide a computer-readable storage medium, which stores a computer program. When the computer program is executed by a processor, the above method is implemented.

[0174] The embodiments of this specification also provide a computer program product, which includes a computer program. When the computer program is executed by a processor, the above method is implemented.

[0175] Those skilled in the art will appreciate that the embodiments of this specification may be provided as methods, systems, or computer program products. Therefore, this specification may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, this specification may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code.

[0176] This specification is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of this specification. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0177] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0178] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0179] The above specific embodiments further illustrate the purpose, technical solutions and beneficial effects of this specification. It should be understood that the above are only specific embodiments of this specification and are not intended to limit the scope of protection of this specification. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of this specification should be included in the scope of protection of this specification.

Claims

1. A gas-liquid two-phase flow measurement method, characterized in that: include: Obtaining a measured volume flow rate, a measured mass flow rate and a measured density corresponding to the gas-liquid two-phase flow to be measured obtained by the measuring device; Collecting a target gas and a target liquid from the gas-liquid two-phase flow to be measured, and calculating a first accurate density corresponding to the target liquid, and calculating a second accurate density corresponding to the target gas based on the gas pressure, the gas temperature and the target gas; Substituting the measured volume flow rate, the measured mass flow rate, the measured density, the first accurate density and the second accurate density into a fitting formula to obtain fitting data; as well as The first accurate density, the second accurate density, the measured volume flow rate, the fitting data and the measured mass flow rate are processed using a mass separation formula to obtain a target gas mass flow rate corresponding to the target gas and a target liquid mass flow rate corresponding to the target liquid.

2. The method according to claim 1, characterized in that The step of sampling a target liquid from the gas-liquid two-phase flow to be measured and calculating a first accurate density corresponding to the target liquid comprises: Static separation of the gas-liquid two-phase flow to be measured to obtain the target liquid in the gas-liquid two-phase flow to be measured; and The target liquid is processed using a liquid density determination model to obtain the first accurate density corresponding to the target liquid.

3. The method according to claim 1, characterized in that The collecting of the target gas from the gas-liquid two-phase flow to be measured and calculating a second accurate density corresponding to the target gas based on the gas pressure, the gas temperature and the target gas comprises: Static separation of the gas-liquid two-phase flow to be measured, and obtaining the target gas in the gas-liquid two-phase flow to be measured; Performing component analysis on the target gas to obtain at least one gas component included in the target gas; and The gas pressure, the gas temperature and the gas component are processed using a gas density determination model to obtain the second accurate density corresponding to the target gas.

4. The method according to claim 1, characterized in that: The process of determining the fitting formula includes: Determine a plurality of experimental operating conditions, wherein the experimental operating conditions include an experimental liquid density and an experimental liquid mass flow rate corresponding to the liquid used for the experiment, an experimental gas density and an experimental gas mass flow rate corresponding to the gas used for the experiment, and an experimental accurate volume flow rate corresponding to an experimental two-phase flow, wherein the experimental two-phase flow is a fluid after the liquid used for the experiment and the gas used for the experiment are mixed; For each of the experimental working conditions, obtaining the experimentally measured mass flow and the experimentally measured density obtained by the measuring device; and The experimental liquid density, the experimental liquid mass flow rate, the experimental gas density, the experimental gas mass flow rate, the experimental accurate volume flow rate, the experimental measured mass flow rate and the experimental measured density corresponding to each of the experimental working conditions are fitted to determine the fitting formula.

5. The method according to claim 4, characterized in that The fitting formula includes: Wherein, the f(V Ah ,ρ Ag ,ρ Al ,ρ M ) characterizes the fitting formula, the m M Characterize the experimentally measured mass flow rate, the m Al Characterize the experimental liquid mass flow rate, the m Ag Characterize the experimental gas mass flow rate, the V Ah Characterize the experimental accurate volume flow rate, the ρ Ag Characterize the experimental gas density, the ρ Al Characterize the experimental liquid density, the ρ M Characterization The experiments measured density.

6. The method according to claim 1, characterized in that The mass separation formula includes: Among them, the m g represents the target gas mass flow rate, V represents the measured volume flow rate, and ρ l represents the first accurate density, the m represents the measured mass flow rate, and the f(V h ,ρ g ,ρ l ,ρ) represents the fitting formula for determining the fitting data, wherein ρ represents the measured density, and V h Characterizes the true volume flow rate, the ρ g The second accurate density is characterized, and the true volume flow rate is the same as the measured volume flow rate.

7. The method according to claim 1, characterized in that The mass separation formula also includes: Among them, the m l represents the target liquid mass flow rate, V represents the measured volume flow rate, and ρ l represents the first accurate density, the m represents the measured mass flow rate, and the f(V h ,ρ g ,ρ l ,ρ) represents the fitting formula for determining the fitting data, wherein ρ represents the measured density, and V h Characterizes the true volume flow rate, the ρ g The second accurate density is characterized, and the true volume flow rate is the same as the measured volume flow rate.

8. A gas-liquid two-phase flow measurement system, characterized in that: It includes a two-phase flow calculation device and a measuring device connected to the two-phase flow calculation device, wherein the measuring device includes a volumetric flow meter, a Coriolis mass flow meter, a pressure measuring device, and a temperature measuring device. The volumetric flow meter is used to measure the measured volume flow of the gas-liquid two-phase flow to be measured, and send the measured volume flow to the two-phase flow calculation device; The Coriolis mass flowmeter is used to measure the measured mass flow and the measured density of the gas-liquid two-phase flow to be measured, and send the measured mass flow and the measured density to the two-phase flow calculation device; The pressure measuring device and the temperature measuring device are used to measure the gas pressure and the gas temperature of the target gas in the gas-liquid two-phase flow to be measured, respectively, and send the gas pressure and the gas temperature to the two-phase flow calculation device; The two-phase flow device receives the measured volume flow rate, measured mass flow rate, measured density, gas pressure and gas temperature; Determine a first accurate density corresponding to the target liquid, and calculate a second accurate density corresponding to the target gas based on the gas pressure, the gas temperature and the target gas; substitute the measured volume flow, the measured mass flow, the measured density, the first accurate density and the second accurate density into a fitting formula to obtain fitting data; and use a mass separation formula to process the first accurate density, the second accurate density, the measured volume flow, the fitting data and the measured mass flow to obtain a target gas mass flow corresponding to the target gas and a target liquid mass flow corresponding to the target liquid.

9. A gas-liquid two-phase flow measurement device, characterized in that: include: An acquisition unit, used for acquiring a measured volume flow rate, a measured mass flow rate and a measured density corresponding to the gas-liquid two-phase flow to be measured obtained by the measuring device; A collection and calculation unit, used for collecting target gas and target liquid from the gas-liquid two-phase flow to be measured, and calculating a first accurate density corresponding to the target liquid, and calculating a second accurate density corresponding to the target gas based on the gas pressure, gas temperature and the target gas; a fitting calculation unit, configured to substitute the measured volume flow, the measured mass flow, the measured density, the first accurate density and the second accurate density into a fitting formula to obtain fitting data; as well as A processing unit is used to process the first accurate density, the second accurate density, the measured volume flow rate, the fitting data and the measured mass flow rate by using a mass separation formula to obtain a target gas mass flow rate corresponding to the target gas and a target liquid mass flow rate corresponding to the target liquid.

10. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the method according to any one of claims 1 to 7 is implemented.

11. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the method of any one of claims 1 to 7 is executed.

12. A computer program product comprising a computer program / instructions, characterized in that The computer program / instructions, when executed by a processor, implement a method according to any one of claims 1-7.

Images