A vortex wet gas phase separation flow measurement method based on disturbance wave height modeling

Abstract

The application provides a vortex wet gas phase separation flow measurement method based on disturbance wave height modeling, which comprises the following steps: collecting pressure, temperature, liquid film fluctuation signal and vortex street signal; then calculating gas density, liquid density and liquid phase surface tension, extracting vortex street frequency and disturbance wave height; calculating apparent gas phase flow value of the vortex flowmeter, gas phase Weber number and liquid phase Reynolds number, calculating over-reading coefficient, and calculating gas phase flow; comparing the gas phase flow obtained by two iterations to determine whether the iteration termination condition is met; if the iteration termination condition is met, the iteration is ended, and the last iteration result is considered as the gas phase flow; if the convergence condition is not met, the iteration calculation is repeated until the calculation converges; then the gas phase apparent flow velocity and the gas phase Weber number are calculated; and finally the actual liquid phase flow is calculated. The application realizes accurate measurement of the gas phase flow by establishing the correlation between the over-reading coefficient and the disturbance wave height to compensate the uncorrected gas phase flow.

Description

Technical Field

[0001] This invention belongs to the field of moisture phase flow measurement, and in particular relates to a vortex-street moisture phase flow measurement method based on disturbance wave height modeling. Background Technology

[0002] Moist two-phase flow is extremely common in industrial processes, such as condensed natural gas containing a small amount of liquid, and wet steam injected into oil wells during heavy oil thermal recovery. Generally speaking, moist two-phase flow refers to gas-liquid two-phase flow with a gas-phase volume content exceeding 95% or a Lockhart parameter below 0.3. Annular mist flow, as a widely existing fluid form, plays a crucial role in many industrial scenarios. Accurate measurement of moist two-phase flow is essential for fields such as energy extraction, safe production, transportation and trade, and energy conservation.

[0003] In heavy oil thermal recovery operations, the accuracy of steam measurement and control directly impacts oil production and efficiency. Given the high viscosity and specific gravity of heavy oil, precise measurement of steam dryness and flow rate is a prerequisite for effective control and a crucial technical guarantee for improving the economics of heavy oil thermal recovery. In the power and electricity generation sector, wet steam is an extremely important working medium. Steam boilers, as a key component of steam power plants, generate steam by heating water with fuel. Steam dryness directly reflects steam quality. Accurate measurement of wet steam not only avoids false boiler output data and improves steam quality but also reduces the amount of saturated water drained from steam delivery pipelines, achieving energy savings. During the flow of moist gas, the measurement of liquid phase flow rate is of paramount importance. Currently, commonly used methods such as X-ray methods, microwave methods, and isokinetic sampling methods face significant challenges in achieving online measurement due to the characteristics of the application scenarios and limitations in operation. Furthermore, these methods significantly increase measurement costs. In general, there is an urgent need for a method that offers higher measurement accuracy and is easy to implement online, addressing the challenge of measuring the gas-liquid phase flow rate in moist air flow. Summary of the Invention

[0004] In view of this, the present invention aims to overcome the deficiencies in the prior art and proposes a method for measuring the phase flow rate of vortex-street moist gas based on disturbance wave height modeling.

[0005] To achieve the above objectives, the technical solution created by this invention is implemented as follows: A method for measuring the phase flow rate of vortex-street moist gas based on disturbance wave height modeling includes the following steps: S1: Acquire pressure, temperature, liquid film fluctuation signals, and vortex street signals; S2. Calculate gas density, liquid density, and liquid surface tension. ，Extract the vortex shedding frequency and the disturbance wave height; S3. Calculate the apparent value of the gas phase flow meter of the vortex flow meter. Q g,apparent This is used as the initial value for the gas phase flow rate during iteration, i.e. Q g = Q g,apparent (1) in, K v For instrument coefficients; S4, Calculation Q g Corresponding apparent gas flow rate U sg , (2) in, D This refers to the inner diameter of the pipe. S5. Calculate the gas phase Weber number. We g As shown in formula (3), (3) S6. Calculate the Reynolds number in the liquid phase. Re l , (4) in, k 1 is a constant coefficient. n 1 and n 2 is a constant power exponent; S7. Calculate the overread coefficient OR. (6) in k 2 is a constant coefficient; n 3 and n 4 is the power constant; S8, Calculate gas phase flow rate Q g , (7) S9. Compare the gas phase flow rates obtained from the two iterations to determine if the iteration termination condition is met. If the iteration termination condition is met, the iteration ends, and the result of the last iteration is considered 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 apparent gas velocity. U sg Harmony and Weiber Numbers We g Calculate the actual liquid flow rate according to equation (8). Q l , (8) in, The dynamic viscosity of the liquid.

[0006] Furthermore, the gas density, liquid density, and liquid surface tension are calculated using pressure and temperature, respectively.

[0007] Furthermore, the iteration termination condition is: And the number of iterations has reached the upper limit. Q g，n This represents the gas phase flow rate obtained in this iteration. Q g，n-1 This represents the gas phase flow rate obtained in the previous iteration.

[0008] Furthermore, the liquid phase Reynolds number Re l The specific values ​​are obtained by fitting the function form described in formula (5). (5).

[0009] Furthermore, the relative error in predicting gas phase volumetric flow rate is within ±1%.

[0010] Furthermore, the relative error in predicting liquid phase volumetric flow rate is within ±15%.

[0011] Furthermore, the liquid phase Reynolds number in step S10 Re l From the formula The calculation yielded the result.

[0012] Compared with existing technologies, the present invention has the following advantages: (1) It can realize the measurement of moisture phase flow rate. This method establishes the overreading coefficient OR and the disturbance wave height. h DW The correlation between these factors is used to compensate for overreading in uncorrected gas phase flow rates, thus enabling gas phase flow rate measurement. Furthermore, an overreading coefficient (OR) and the gas phase Weber number are established. We g and liquid phase Reynolds number Re l The model between the two phases is used to solve for the liquid phase flow rate, and finally the wet gas phase flow rate measurement is realized.

[0013] (2) Simple, low-cost, online measurement Moisture phase flow rate can be measured by using a vortex flow meter, liquid film thickness sensor, pressure sensor, and temperature sensor to measure relevant parameters. This method is simple to operate, low in cost, and can be performed online.

[0014] (3) High prediction accuracy The method was used to predict gas and liquid flow rates under humid conditions. In the example, the relative error for gas volumetric flow rate prediction was within ±1%, and the relative error for liquid volumetric flow rate prediction was within ±15%. Attached Figure Description

[0015] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments and descriptions of the invention are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a schematic diagram of the overall measuring device; Figure 2 This is a flowchart of the signal acquisition process; Figure 3 For the height of the disturbance wave h DW Compared with gas phase Weber number and liquid phase Reynolds number Re l Modeling a relationship diagram; Figure 4 The overreading factor OR is related to the gas phase Weber number and the liquid phase Reynolds number. Re l Modeling a relationship diagram; Figure 5 For the phase of Weber number We g Gas phase flow rate Q g Relationship diagram; Figure 6 For liquid phase Reynolds number Re l With liquid phase flow rate Q l Relationship diagram.

[0016] Explanation of reference numerals in the attached figures: 1-Annular electrode; 2-Pressure sensor; 3-Vortex flow meter; 4-Temperature sensor. Detailed Implementation

[0017] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0018] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0019] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0020] The invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0021] This invention uses a liquid film thickness sensor and a vortex flowmeter to measure the average liquid film thickness and the uncorrected gas phase flow rate, respectively. The average liquid film thickness under different inlet conditions is extracted, and a correlation between the overreading coefficient and the gas phase Weber number and liquid phase Reynolds number is established to address the vortex overreading problem. Gas phase flow rate measurement is achieved by compensating for the overreading of the uncorrected gas phase flow rate. To solve for the liquid phase flow rate, a model is further established between the average disturbance wave height and the gas phase Weber number and liquid phase Reynolds number, ultimately realizing the measurement of phase-separated flow rates under humid conditions. The specific solution method is as follows: S1, Acquisition Pressure p ,temperature T Liquid film fluctuation signal δ ( t ) and vortex street signal s ( t ); S2, through pressure p and temperature T Calculate the gas density separately Liquid density and liquid phase surface tension ， Extracting vortex shedding frequency using the FFT algorithm f vs And extract the height of the disturbance wave. h DW ; S3. Calculate the apparent value of the gas phase flow rate of the vortex flow meter according to formula (1). Q g,apparent This is used as the initial value for the gas phase flow rate during iteration, i.e. Q g = Q g,apparent (1) in, K v Instrument coefficient S4. Calculate according to formula (2) Q g Corresponding apparent gas flow rate U sg (2) in, D This refers to the inner diameter of the pipe. S5. Calculate the gas phase Weber number. We g As shown in formula (3) (3) S6. Calculate the liquid phase Reynolds number using formula (4). Re l (4) in, k 1 is a constant coefficient. n 1 and n 2 is a constant power exponent, and its specific value is obtained by fitting the function form described in formula (5). (5) S7. Calculate the overread coefficient OR according to formula (6). (6) in k 2 is a constant coefficient; n 3 and n 4 is the power constant; S8. Calculate the gas phase flow rate using equation (7). Q g (7) S9. Compare the gas phase flow rates obtained from the two iterations to determine whether the iteration termination condition is met. And the number of iterations has reached the upper limit. Q g，n This represents the gas phase flow rate obtained in this iteration. Q g，n-1 This represents the gas phase flow rate obtained in the previous iteration. If the iteration termination condition is met, the iteration ends, and the result of the last iteration 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. S10. Calculate the apparent gas velocity. U sg Harmony and Weiber Numbers We g The liquid phase Reynolds number is calculated using formula (4). Re l The actual liquid flow rate is calculated according to equation (8). Q l (8) in, The dynamic viscosity of the liquid.

[0022] Based on the above method, the measurement of vortex flow moisture phase flow was finally realized.

[0023] The following implementation provides a method for measuring the phase flow rate of vortex-street moist gas based on disturbance wave height modeling. This is a typical implementation in moist gas measurement. Specifically, it utilizes the multi-parameter adjustable mist flow experimental system described in patent 201810644726.7, adjusting the moist gas pressure to 150 kPa ~ 350 kPa and the gas phase flow rate to 12 m³ / s. 3 / h ~ 24 m 3 / h, liquid flow rate 0.55 mL / s ~ 4.5 mL / s, pipe diameter is constant. D =15 mm, the surface tension of the liquid is constant. σ= 0.072 N / m. A schematic diagram of the overall measuring device is attached. Figure 1 As shown, it consists of an annular electrode 1, a pressure sensor 2, a vortex flow meter 3, and a temperature sensor 4.

[0024] like Figures 1 to 6 As shown, liquid film ripple signals are obtained by utilizing the conductivity characteristics of the liquid film through two annular electrodes 1 arranged on the inner side of the pipe wall. δ ( t The signal acquisition flowchart is attached. Figure 2As shown. Sensor signals are acquired, including the operating pressure output by the pressure sensor. p Operating temperature output by the temperature sensor T The vortex timing sequence number output by the vortex flow meter s ( t And the liquid film fluctuation signal output by the liquid film thickness sensor in patent CN201910134650.8 δ ( t ).in s ( t The sampling frequency is 100 kHz, and the sampling time for each data set is 10 s. δ ( t The sampling frequency is 32 MHz. Under the excitation of a sinusoidal signal (500 kHz), it samples 64 times in each cycle. After 8 cycles of sampling, the data is processed by the host computer.

[0025] Then, through p and T Calculate the gas density under the corresponding operating conditions. ρ g and liquid density ρ l Timing signals for vortex flow meters s ( t Perform a Fast Fourier Transform to extract the frequency of the vortex shedding signal. f VS .

[0026] A vortex flow meter is a velocity flow meter that measures the frequency of vortex shedding. f VS Volumetric flow rate can then be obtained. in K v The instrument coefficient (m) of the vortex flow meter in single-phase gas -3 ).

[0027] In moist gas flow, the presence of a small amount of liquid phase makes the measured gas volumetric flow rate different when using a vortex flowmeter to measure moist gas. Q g,apparent Flow rate higher than that of actual gas Q g This is known as the "overreading" phenomenon. Therefore, the reading of the vortex flowmeter... Q g,apparent Compared with actual traffic Q g The relationship between them is In the formula, OR is called the vortex street overreading coefficient.

[0028] To improve the measurement accuracy of vortex flowmeters, an OR prediction model needs to be established to correct the flowmeter readings. Past studies often used droplet parameters to build OR prediction models, but these parameters are often difficult to measure directly. Liquid film parameters can also characterize the internal flow characteristics of fluids, and they are easier to obtain. Next, based on the average liquid film thickness... δ A vortex overreading coefficient OR prediction model was established, and an average liquid film thickness was also established. δ Predictive models.

[0029] The disturbance wave height was obtained by fitting the experimental data using the least squares method. h DW With the phase of the Weber number We g and liquid phase Reynolds number Re l Relationship between them: in, D This refers to the pipe diameter.

[0030] Under the experimental conditions, the vortex overreading coefficient OR and the gas phase Weber number were obtained by fitting the experimental data using the least squares method. We g and liquid phase Reynolds number ​ l Relationship between them: Based on the above modeling and calibration results, the wet gas phase flow rate is measured, and the implementation process is as follows: 1) Acquisition pressure p ,temperature T Liquid film fluctuation signal ​ ( t ) and vortex street signal s ( t ); 2) Through pressure p and temperature T Calculate the gas density separately Liquid density and liquid phase surface tension ， Extracting vortex shedding frequency using the FFT algorithm f vs And extract the height of the disturbance wave. h DW ; 3) Calculate the apparent value of the gas phase flow rate of the vortex flow meter according to formula (1). Q g,apparent This is used as the initial value for the gas phase flow rate during iteration, i.e. Qg = Q g,apparent (1) in, K v Instrument coefficient 4) Calculate according to formula (2) Q g Corresponding apparent gas flow rate U sg (2) in, D This refers to the inner diameter of the pipe. 5) Calculate the gas phase Weber number. ​ g As shown in formula (3) (3) 6) Calculate the liquid phase Reynolds number using formula (4). ​ l (4) in, k 1 is a constant coefficient. n 1 and n 2 is a constant power exponent, and its specific value is obtained by fitting the function form described in formula (5). (5) 7) Calculate the overread coefficient OR according to formula (6). (6) in k 2 is a constant coefficient; n 3 and n 4 is the power constant; 8) Calculate the gas phase flow rate using equation (7) Q g (7) 9) Compare the gas phase flow rates obtained in the two iterations to determine whether the iteration termination condition is met. And the number of iterations has reached the upper limit. Q g，n This represents the gas phase flow rate obtained in this iteration. Q g，n-1 This represents the gas phase flow rate obtained in the previous iteration. If the iteration termination condition is met, the iteration ends, and the result of the last iteration is considered to be the gas phase flow rate. Qg 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. 10) Calculate the apparent gas velocity. U sg Harmony and Weiber Numbers ​ g The liquid phase Reynolds number is calculated using formula (4). ​ l The actual liquid flow rate is calculated according to equation (8). Q l (8) in, The dynamic viscosity of the liquid.

[0031] Based on the above method, the measurement of vortex flow moisture phase flow was finally realized.

[0032] To verify the proposed vortex-street wet gas phase flow measurement method based on disturbance wave height modeling, the gas phase volumetric flow rate was predicted using liquid film thickness. The relative error of the gas phase volumetric flow rate prediction was within ±1%, where the relative error = (predicted value - actual value) / actual value × 100. The relative error of the liquid phase flow rate prediction under different operating conditions was within ±15%.

[0033] This invention utilizes the disturbance wave height information of the liquid film to correct and compensate for the overreading OR of vortex street measurements, and establishes a correlation between vortex street overreading and the gas phase Weber number and liquid phase Reynolds number. Finally, the gas phase flow rate and liquid phase flow rate are obtained. 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.

[0034] The above description is merely 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 within the protection scope of the present invention.

Claims

1. A method for measuring the phase flow rate of vortex-street moist gas based on disturbance wave height modeling, characterized in that, Includes the following steps: S1: Acquire pressure, temperature, liquid film fluctuation signals, and vortex street signals; S2, Calculate gas density Liquid density and liquid phase surface tension ， Extracting vortex frequency f vs And extract the height of the disturbance wave. h DW ; S3. Calculate the apparent value of the gas phase flow meter of the vortex flow meter. Q g,apparent This is used as the initial value for the gas phase flow rate during iteration, i.e. Q g = Q g,apparent (1) in, K v For instrument coefficients; S4, Calculation Q g Corresponding apparent gas flow rate U sg , (2) in, D This refers to the inner diameter of the pipe. S5. Calculate the gas phase Weber number. We g As shown in formula (3), (3) S6. Calculate the Reynolds number in the liquid phase. Re l , (4) in, k 1 is a constant coefficient. n 1 and n 2 is a constant power exponent; S7. Calculate the overread coefficient OR. (6) in k 2 is a constant coefficient; n 3 and n 4 is the power constant; S8, Calculate gas phase flow rate Q g , (7) S9. Compare the gas phase flow rates obtained from the two iterations to determine if the iteration termination condition is met. If the iteration termination condition is met, the iteration ends, and the result of the last iteration is considered 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 apparent gas velocity. U sg Harmony and Weiber Numbers We g Calculate the actual liquid flow rate according to equation (8). Q l , (8) in, This represents the dynamic viscosity of the liquid.

2. The method for measuring the phase flow rate of vortex-street moist gas based on disturbance wave height modeling according to claim 1, characterized in that: Gas density, liquid density, and liquid surface tension are calculated using pressure and temperature, respectively.

3. The method for measuring the phase flow rate of vortex-street moist gas based on disturbance wave height modeling according to claim 1, characterized in that: The iteration termination condition is And the number of iterations has reached the upper limit. Q g，n This represents the gas phase flow rate obtained in this iteration. Q g，n-1 This represents the gas phase flow rate obtained in the previous iteration.

4. The method for measuring the phase flow rate of vortex-street moist gas based on disturbance wave height modeling according to claim 1, characterized in that: Liquid phase Reynolds number Re l The specific values ​​are obtained by fitting the function form described in formula (5). (5)。 5. The method for measuring the phase flow rate of vortex-street moist gas based on disturbance wave height modeling according to claim 1, characterized in that: The relative error for gas phase volumetric flow rate prediction is within ±1%.

6. The method for measuring the phase flow rate of vortex-street moist gas based on disturbance wave height modeling according to claim 1, characterized in that: Liquid volumetric flow rate prediction has a relative error within ±15% across the entire range.

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