Vortex street moisture split-phase flow measurement method based on disturbance wave height modeling

Abstract

The invention provides a vortex street moisture split-phase flow measuring method based on disturbance wave height modeling. The vortex street moisture split-phase flow measuring method comprises the steps that firstly, pressure, temperature and liquid film fluctuation signals and vortex street signals are collected; then calculating gas density, liquid density and liquid phase surface tension, and extracting vortex street frequency and disturbance wave height; calculating a gas phase flow meter observation value, a gas phase Weibull number and a liquid phase Reynolds number of the vortex shedding flowmeter, calculating an overread coefficient, calculating gas phase flow, comparing the gas phase flow obtained by two iterations, judging whether an iteration termination condition is met or not, if the iteration termination condition is met, ending the iteration, and considering that the last iteration result is the gas phase flow; if the convergence condition is not met, iterative calculation is repeated until calculation is converged; then the gas phase apparent velocity and the gas phase Weber number are solved; and finally calculating the actual liquid phase flow. According to the method, the correlation between the overread coefficient and the disturbance wave height is established, overread compensation is carried out on the uncorrected gas phase flow, and accurate measurement of the gas phase flow is achieved.

Description

Technical Field

[0001] The invention belongs to the field of wet gas phase flow measurement, and in particular relates to a vortex street wet gas phase flow measurement method based on disturbance wave height modeling. Background Art

[0002] Wet gas two-phase flow is extremely common in industrial processes. Examples include natural gas condensate containing small amounts of liquid and wet steam injected into oil wells during heavy oil thermal recovery. Generally speaking, wet gas two-phase flow refers to gas-liquid two-phase flow with a gas phase volume fraction exceeding 95%, or a Lockheed Martin parameter below 0.3. Annular mist flow, as a widespread fluid form, plays a key role in numerous industrial scenarios. Accurately measuring wet gas two-phase flow is crucial for energy extraction, safe production, transportation and trade, and energy conservation.

[0003] In heavy oil thermal recovery operations, the accuracy of steam measurement and control has a direct impact on oil production and efficiency. Given the unique physical properties of heavy oil, such as high viscosity and specific gravity, accurate measurement of steam dryness and flow is a prerequisite for effective control and a crucial technical guarantee for improving the economic efficiency of heavy oil thermal recovery. In the power and power generation sectors, wet steam is a crucial working medium. Steam boilers, as key components of steam power plants, generate steam by heating water with fuel. Steam dryness directly reflects the quality of the steam. Accurate wet steam measurement not only prevents false boiler output data and improves steam quality, but also reduces the amount of saturated water in steam pipelines, thereby saving energy. Measuring liquid flow is crucial in wet gas flow. Currently, commonly used methods, such as radiography, microwaves, and isokinetic sampling, face significant challenges in achieving online measurement due to the specifics of their application scenarios and operational limitations. Furthermore, these methods significantly increase measurement costs. In general, in order to solve the problem of measuring the gas-liquid phase flow rate in wet gas flow, there is an urgent need for a method with higher measurement accuracy and easy implementation of online measurement. Summary of the Invention

[0004] In view of this, the present invention aims to overcome the defects in the prior art and proposes a vortex street wet gas phase flow measurement method based on disturbance wave height modeling.

[0005] To achieve the above object, the technical solution created by the present invention is implemented as follows:

[0006] A method for measuring vortex wet gas phase flow rate based on disturbance wave height modeling includes the following steps:

[0007] S1, collect pressure, temperature, liquid film fluctuation signal and vortex signal;

[0008] S2. Calculate gas density, liquid density, and liquid surface tension, extract vortex frequency, and extract disturbance wave height;

[0009] S3. Calculate the apparent value Q of the gas phase flow rate of the vortex flowmeter g,apparent , which is used as the initial value of the iteration of the gas phase flow rate, namely Q g =Q g,apparent

[0010]

[0011] Among them, K v is the instrument factor;

[0012] S4. Calculate Q g The corresponding gas phase superficial velocity U sg ,

[0013]

[0014] Where D is the inner diameter of the pipe;

[0015] S5. Calculate the gas phase Weber number We g , as shown in formula (3),

[0016]

[0017] S6. Calculate the liquid phase Reynolds number Re l ,

[0018]

[0019] Among them, k1 is the coefficient constant, n1 and n2 are constant power exponents;

[0020] S7, calculate the overread coefficient OR,

[0021]

[0022] Where k2 is the coefficient constant; n3 and n4 are power exponential constants;

[0023] S8. Calculate gas phase flow rate Q g ,

[0024]

[0025] S9, compare the gas phase flow rates obtained from the two iterations before and after, and determine whether the iteration termination condition is met. If the iteration termination condition is met, the iteration ends, and the last iteration result is considered to be the gas phase flow rate Q g If the convergence condition is not met, jump to step S4 and repeat the iterative calculation of steps S4 to S9 until the calculation converges;

[0026] S10. Calculate the gas phase apparent velocity U sg and gas phase Weber number We g ; Calculate the actual liquid flow rate Q according to formula (8) l ,

[0027]

[0028] Where m is the dynamic viscosity of the liquid.

[0029] Furthermore, the gas density, liquid density and liquid surface tension are calculated respectively by pressure and temperature.

[0030] Furthermore, the iteration termination condition is |Q g,n -Q g,n-1 | / Q g,n-1 <ε, and the number of iterations reaches the upper limit, Q g，n represents the gas phase flow rate obtained in this iteration, Q g，n-1 Represents the gas phase flow rate obtained in the previous iteration.

[0031] Furthermore, the liquid phase Reynolds number Re l The specific value is obtained by fitting the function form described in formula (5).

[0032]

[0033] Furthermore, the relative error of the gas phase volume flow rate prediction is within ±1%.

[0034] Furthermore, the relative error of the liquid phase volume flow rate prediction is within ±15%.

[0035] Furthermore, the liquid phase Reynolds number Re in step S10 l By the formula Calculated.

[0036] Compared with the prior art, the present invention has the following advantages:

[0037] (1) Able to measure wet gas phase flow

[0038] This method establishes the overread coefficient OR and the disturbance wave height h DW The correlation formula between the over-reading compensation of the uncorrected gas phase flow rate is established to achieve gas phase flow measurement. And the over-reading coefficient OR and the gas phase Weber number We g and liquid phase Reynolds number Re l The model between them is used to solve the liquid phase flow rate and finally realize the wet gas phase flow measurement.

[0039] (2) Simple, low-cost, online measurement

[0040] By measuring relevant parameters using a vortex flowmeter, a liquid film thickness sensor, a pressure sensor, and a temperature sensor, wet gas phase flow measurement can be achieved. This method is simple to operate, low-cost, and can achieve online measurement.

[0041] (3) High prediction accuracy

[0042] This method was used to predict gas and liquid flow rates under wet gas conditions. The gas volume flow rate prediction achieved a relative error within ±1%, while the liquid volume flow rate prediction achieved a relative error within ±15%. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The accompanying drawings, which constitute part of the present invention, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0044] Figure 1 is the overall schematic diagram of the measuring device;

[0045] Figure 2 This is the signal acquisition flow chart;

[0046] Figure 3 is the disturbance wave height h DW The gas phase Weber number and liquid phase Reynolds number Re l Modeling relationship diagram;

[0047] Figure 4 is the overreading coefficient OR and the gas phase Weber number and liquid phase Reynolds number Re l Modeling relationship diagram;

[0048] Figure 5 is the gas phase Weber number We g and gas phase flow rate Q g Relationship diagram;

[0049] Figure 6 is the liquid phase Reynolds number Re l and liquid flow rate Q l Relationship diagram.

[0050] Description of reference numerals:

[0051] 1- Ring electrode; 2- Pressure sensor; 3- Vortex flowmeter; 4- Temperature sensor. DETAILED DESCRIPTION

[0052] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other.

[0053] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second" and the like are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, features defined as "first", "second" and the like may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0054] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to internal connections between two components. Those skilled in the art can understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0055] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments.

[0056] The present invention uses a liquid film thickness sensor and a vortex flowmeter to measure the average liquid film thickness and the uncorrected gas phase flow, respectively. The average liquid film thickness under different inlet conditions is extracted, and a correlation formula between the overreading coefficient and the gas phase Weber number and the liquid phase Reynolds number is established to address the vortex overreading problem. By overreading compensation for the uncorrected gas phase flow, gas phase flow measurement is achieved. To solve the liquid phase flow, a model is further established between the average disturbance wave height and the gas phase Weber number and the liquid phase Reynolds number, ultimately achieving phase flow measurement under wet conditions. The specific solution method is as follows:

[0057] S1, collect pressure p, temperature T, liquid film fluctuation signal (t) and vortex signal s(t);

[0058] S2. Calculate the gas density g, liquid density l and liquid surface tension respectively by pressure p and temperature T, and extract the vortex frequency f using FFT algorithm. vs , and extract the disturbance wave height h DW ;

[0059] S3. According to formula (1), calculate the apparent value Q of the vortex flowmeter gas phase flowg,apparent , which is used as the initial value of the iteration of the gas phase flow rate, namely Q g =Q g,apparent

[0060]

[0061] Among them, K v is the instrument factor

[0062] S4. Calculate Q according to formula (2) g The corresponding gas phase superficial velocity U sg

[0063]

[0064] Where D is the inner diameter of the pipe;

[0065] S5. Calculate the gas phase Weber number We g , as shown in formula (3)

[0066]

[0067] S6. Calculate the liquid phase Reynolds number Re by formula (4) l

[0068]

[0069] Where k1 is the coefficient constant, n1 and n2 are constant power exponents, and their specific values ​​are obtained by fitting the function form described in formula (5):

[0070]

[0071] S7. Calculate the overread coefficient OR according to formula (6)

[0072]

[0073] Where k2 is the coefficient constant; n3 and n4 are power exponential constants;

[0074] S8. Calculate the gas phase flow rate Q by formula (7) g

[0075]

[0076] S9. Compare the gas phase flow rates obtained from the two iterations to determine whether the iteration termination condition |Q is met. g,n -Q g,n-1 | / Q g,n-1 <ε and the number of iterations reaches the upper limit, Q g，n represents the gas phase flow rate obtained in this iteration, Q g，n-1Represents the gas phase flow rate obtained in the last iteration. If the iteration termination condition is met, the iteration ends and the last iteration result is considered to be the gas phase flow rate Q g If the convergence condition is not met, jump to step (4) and repeat the iterative calculation of steps (4) to (9) until the calculation converges.

[0077] S10. Calculate the gas phase apparent velocity U sg and gas phase Weber number We g ; Calculate the liquid phase Reynolds number Re by formula (4) l , calculate the actual liquid flow Q according to formula (8) l

[0078]

[0079] Where m is the dynamic viscosity of the liquid.

[0080] According to the above method, the vortex flow wet gas phase separation flow measurement was finally realized.

[0081] The following implementation provides a vortex street wet gas phase flow measurement method based on disturbance wave height modeling, which is usually implemented in wet gas measurement. Specifically, the multi-parameter adjustable mist flow experimental system in patent 201810644726.7 can be used to adjust the wet gas working pressure to 150kPa~350kPa and the gas phase flow rate to 12m 3 / h~24m 3 / h, liquid flow rate 0.55mL / s~4.5mL / s, pipe diameter is fixed value D=15mm, liquid surface tension is fixed value σ=0.072N / m. The overall schematic diagram of the measuring device is shown in the attached figure. Figure 1 As shown, it consists of a ring electrode 1, a pressure sensor 2, a vortex flowmeter 3 and a temperature sensor 4.

[0082] like Figures 1 to 6 As shown, by arranging two annular electrodes 1 on the inner side of the pipe wall, the liquid film thickness sequence d(t) is obtained by utilizing the conductivity characteristics of the liquid film. The signal acquisition flow chart is shown in the attached figure. Figure 2 As shown in the figure. Sensor signals are collected, including the operating pressure p output by the pressure sensor, the operating temperature T output by the temperature sensor, the vortex time sequence number s(t) output by the vortex flowmeter, and the liquid film thickness time sequence signal δ(t) output by the liquid film thickness sensor in patent CN201910134650.8. The sampling frequency of s(t) is 100kHz, and the sampling time for each set of data is 10s. The sampling frequency of δ(t) is 32MHz. Under the excitation of a sinusoidal signal (500kHz), 64 samples are sampled in each cycle. After 8 sampling cycles, it is handed over to the host computer for processing.

[0083] Then, the gas density ρ under the corresponding working conditions is calculated by p and T respectively g and liquid density ρ l ; Perform fast Fourier transform on the time series signal s(t) of the vortex flowmeter to extract the frequency f of the vortex signal VS .

[0084] Vortex flowmeter is a velocity flowmeter that measures the vortex shedding frequency f VS The volume flow rate can be obtained

[0085]

[0086] where K v is the instrument factor of the vortex flowmeter in single-phase gas (m -3 ).

[0087] In the wet gas flow, the presence of a small amount of liquid phase makes the measured gas phase volume flow rate Q g,apparent Higher than the actual gas flow rate Q g , which is called "over-reading". Therefore, the vortex flowmeter shows Q g,apparent and the actual flow Q g The relationship between

[0088]

[0089] Where OR is called the vortex over-reading coefficient.

[0090] To improve the measurement accuracy of vortex flowmeters, an OR prediction model is needed to correct the vortex flowmeter reading. Previous studies often used droplet parameters to develop OR prediction models, but these parameters are often difficult to directly measure. Liquid film parameters can also characterize the internal flow characteristics of a fluid and are much easier to obtain. Next, an OR prediction model for the vortex overreading coefficient and an average liquid film thickness prediction model were developed based on the average liquid film thickness δ.

[0091] The experimental data were fitted by the least squares method to obtain the disturbance wave height h shown in DW and the gas phase Weber number We g and liquid phase Reynolds number Re l Relationship between:

[0092]

[0093] Where D is the pipe diameter.

[0094] Under the experimental conditions, the experimental data were fitted by the least squares method to obtain the vortex street over-reading coefficient OR and the gas phase Weber number We shown in the figure. g and liquid phase Reynolds number Re lRelationship between:

[0095] OR=1+1.9393We g -0.7293 Re l 0.4122

[0096] Based on the above modeling and calibration results, wet gas phase flow measurement is carried out. The implementation process is as follows:

[0097] 1) Collect pressure p, temperature T, liquid film fluctuation signal (t) and vortex signal s(t);

[0098] 2) Calculate the gas density g, liquid density l and liquid surface tension respectively by pressure p and temperature T, and extract the vortex frequency f using the FFT algorithm vs , and extract the disturbance wave height h DW ;

[0099] 3) According to formula (1), calculate the apparent value Q of the vortex flowmeter gas phase flow rate g,apparent , which is used as the initial value of the iteration of the gas phase flow rate, namely Q g =Q g,apparent

[0100]

[0101] Among them, K v is the instrument factor

[0102] 4) Calculate Q according to formula (2) g The corresponding gas phase superficial velocity U sg

[0103]

[0104] Where D is the inner diameter of the pipe;

[0105] 5) Calculate the gas phase Weber number We g , as shown in formula (3)

[0106]

[0107] 6) Calculate the liquid phase Reynolds number Re by formula (4) l

[0108]

[0109] Where k1 is the coefficient constant, n1 and n2 are constant power exponents, and their specific values ​​are obtained by fitting the function form described in formula (5):

[0110]

[0111] 7) According to formula (6), the overread coefficient OR is calculated

[0112] OR=1+1.9393We g -0.7293 Re l 0.4122 (6)

[0113] Where k2 is the coefficient constant; n3 and n4 are power exponential constants;

[0114] 8) Calculate the gas phase flow rate Q by formula (7) g

[0115]

[0116] 9) Compare the gas phase flow obtained from the two iterations to determine whether the iteration termination condition |Q is met g,n -Q g,n-1 | / Q g,n-1 <ε and the number of iterations reaches the upper limit, Q g，n represents the gas phase flow rate obtained in this iteration, Q g，n-1 Represents the gas phase flow rate obtained in the last iteration. If the iteration termination condition is met, the iteration ends and the last iteration result is considered to be the gas phase flow rate Q g If the convergence condition is not met, jump to step (4) and repeat the iterative calculation of steps (4) to (9) until the calculation converges.

[0117] 10) Calculate the gas phase apparent velocity U sg and gas phase Weber number We g ; Calculate the liquid phase Reynolds number Re by formula (4) l , calculate the actual liquid flow Q according to formula (8) l

[0118]

[0119] Where m is the dynamic viscosity of the liquid.

[0120] According to the above method, the vortex flow wet gas phase separation flow measurement was finally realized.

[0121] To verify the proposed vortex wet gas flow measurement method based on disturbance wave height modeling, the gas phase volume flow rate was predicted using liquid film thickness. The relative error of the gas phase volume flow rate prediction was within ±1%, where relative error = (predicted value - true value) / true value × 100. The relative error of the liquid phase flow rate prediction under different operating conditions was within ±15%.

[0122] The present invention utilizes the disturbance wave height information of the liquid film to correct and compensate for the overreading OR of the vortex street measurement, and establishes a correlation formula between the vortex street overreading and the gas phase Weber number and the liquid phase Reynolds number, and finally obtains the gas phase flow rate and the liquid phase flow rate. No other complex and expensive gas and liquid phase measurement devices and methods are required. The measurement method is simple, economical and has high prediction accuracy.

[0123] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for measuring vortex wet gas phase flow based on disturbance wave height modeling, characterized in that: The following steps are involved: S1, collect pressure, temperature, liquid film fluctuation signal and vortex signal; S2, calculate the gas density, liquid density and liquid surface tension, extract the vortex frequency, and extract the disturbance wave height; S3. Calculate the apparent value Q of the gas phase flow rate of the vortex flowmeter g,apparent , which is used as the initial value of the iteration of the gas phase flow rate, namely Q g =Q g,apparent Among them, K v is the instrument factor; S4. Calculate Q g The corresponding gas phase superficial velocity U sg , Where D is the inner diameter of the pipe; S5. Calculate the gas phase Weber number We g , as shown in formula (3), S6. Calculate the liquid phase Reynolds number Re l , Among them, k1 is the coefficient constant, n1 and n2 are constant power exponents; S7, calculate the overread coefficient OR, Where k2 is the coefficient constant; n3 and n4 are power exponential constants; S8. Calculate gas phase flow rate Q g , S9, compare the gas phase flow rates obtained from the two iterations before and after, and determine whether the iteration termination condition is met. If the iteration termination condition is met, the iteration ends, and the last iteration result is considered to be the gas phase flow rate Q g If the convergence condition is not met, jump to step S4 and repeat the iterative calculation of steps S4 to S9 until the calculation converges; S10. Calculate the gas phase apparent velocity U sg and gas phase Weber number We g ; Calculate the actual liquid flow rate Q according to formula (8) l , Where m is the dynamic viscosity of the liquid.

2. The method for measuring vortex wet gas phase flow rate based on disturbance wave height modeling according to claim 1 is characterized in that: Calculate gas density, liquid density, and liquid surface tension using pressure and temperature, respectively.

3. The method for measuring vortex wet gas phase flow rate based on disturbance wave height modeling according to claim 1 is characterized in that: The iteration termination condition is |Q g,n -Q g,n-1 | / Q g,n-1 <ε, and the number of iterations reaches the upper limit, Q g，n represents the gas phase flow rate obtained in this iteration, Q g，n-1 Represents the gas phase flow rate obtained in the previous iteration.

4. The method for measuring vortex wet gas phase flow rate based on disturbance wave height modeling according to claim 1 is characterized in that: Liquid phase Reynolds number Re l The specific value is obtained by fitting the function form described in formula (5).

5. The method for measuring vortex wet gas phase flow rate based on disturbance wave height modeling according to claim 1 is characterized in that: The relative error of gas phase volume flow prediction is within ±1%.

6. The method for measuring vortex wet gas phase flow rate based on disturbance wave height modeling according to claim 1 is characterized in that: Liquid phase volume flow prediction, full range relative error is within ±15%.

7. The method for measuring vortex wet gas phase flow rate based on disturbance wave height modeling according to claim 1 is characterized in that: The liquid phase Reynolds number Re in step S10 l By the formula Calculated.

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