A method for measuring the flow rate of multiphase flow using beta rays

Abstract

The application discloses a kind of with beta-ray realizes multiphase flow measurement method, steps are as follows: S1.gas temperature variation coefficient, pressure variation coefficient and flow rate variation coefficient are calculated;S2.under the condition of set pressure and set temperature, the residual attenuation of gas under different set speed is calculated, and the mass absorption coefficient of non-newtonian fluid is calculated;S3.when measuring the mass flow of measured non-newtonian fluid in field environment, the field flow rate of measured non-newtonian fluid, field pressure and field temperature and the residual attenuation of measured non-newtonian fluid are measured, and the residual attenuation of flowing gas in field environment is calculated;S4.measure the field flow rate of measured non-newtonian fluid in field environment, and calculate the density of measured non-newtonian fluid;S5.the mass flow of measured non-newtonian fluid is calculated.The application improves the accuracy of the residual attenuation calculation of gas by analyzing the influencing factors of beta-ray, and then accurately calculates the flow of non-newtonian fluid.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of measurement methods of multiphase flow, specifically a kind of measurement methods of multiphase flow with beta ray. BACKGROUND

[0002] Measurement is the eye of industrial production, and flow measurement is one of the components of measurement science and technology, which is closely related to national economy, national defense construction and scientific research. Good work plays an important role in ensuring product quality, improving production efficiency and promoting scientific and technological development, especially in today's era of energy crisis and increasing industrial production automation, the role of flow measurement in the national economy is more obvious.

[0003] Flow measurement is widely used in industrial production, agricultural production, national defense construction, scientific research, foreign trade and various fields of people's life. In the production of crude oil, from the exploitation, transportation, smelting and processing of crude oil to trade sales, flow measurement is throughout the whole process, and any link cannot be separated from flow measurement, otherwise the normal production and trade of the oil industry cannot be ensured.

[0004] Non-Newtonian fluid is a typical multiphase flow. Common non-Newtonian fluids include solid-liquid two-phase flow (crude oil and blood), and two immiscible liquid mixtures liquid-liquid two-phase flow (such as oil and water). Non-Newtonian fluid usually contains gas during pipeline transportation. It is difficult to determine the specific gravity and flow of gas, solid or liquid in multiphase flow by using traditional measurement methods. In multiphase flow, important parameters such as flow rate, volume flow, density, etc. are often needed to measure and control them. Direct measurement of non-Newtonian fluid containing gas is difficult, and under complex measurement environment and working conditions, the interference of temperature, pressure, flow rate, humidity and other working conditions leads to large deviation of direct measurement data, and often invalid data appears. SUMMARY

[0005] The purpose of the present application is to provide a measurement method for multiphase flow using beta rays to solve the problem of inaccurate flow measurement of non-Newtonian fluid containing gas.

[0006] The purpose of the present application is achieved as follows:

[0007] A measurement method for multiphase flow using beta rays, comprising the following steps:

[0008] S1. Under the condition of constant pressure, measure the residual attenuation of beta rays passing through gas with a flow rate of 0 at least two different temperatures, respectively; calculate the temperature variation coefficient according to the residual attenuation at different temperatures.

[0009] S2. Under the condition that the temperature is constant, the residual attenuation of the β-ray passing through the gas with a flow rate of 0 is measured at least at two different pressures respectively; and the pressure variation coefficient is calculated according to the residual attenuation at different pressures;

[0010] S3. Under the condition that the temperature and the pressure are constant, the residual attenuation of the β-ray passing through the gas is measured at least at two different flow rates respectively; and the flow rate variation coefficient is calculated according to the residual attenuation at different flow rates;

[0011] S4. Under the condition that the pressure and the temperature are set, a certain amount of non-Newtonian fluid is put into the measuring chamber to flow at a set speed, and the non-Newtonian fluid does not fill the cross section of the measuring chamber during the flow process, the residual attenuation of the β-ray passing through the non-Newtonian fluid is measured, and the residual attenuation of the β-ray passing through the gas at the set speed is calculated according to the set pressure and the set temperature; the set speed is changed at least 10 times, and at least 10 times of the residual attenuation of the non-Newtonian fluid and the residual attenuation of the gas are obtained, and the mass absorption coefficient of the non-Newtonian fluid containing the gas is calculated according to the measured residual attenuation of the gas and the residual attenuation of the non-Newtonian fluid each time;

[0012] S5. When measuring the mass flow of the measured non-Newtonian fluid in the field environment, the field flow rate, the field pressure and the field temperature of the measured non-Newtonian fluid are measured, and the residual attenuation of the flowing gas in the field environment is calculated according to the temperature variation coefficient, the pressure variation coefficient, the flow rate variation coefficient, the field flow rate, the field pressure and the field temperature of the measured non-Newtonian fluid;

[0013] S6. The residual attenuation of the measured non-Newtonian fluid in the field environment is measured, and the density of the measured non-Newtonian fluid is calculated according to the residual attenuation of the flowing gas in the field environment, the residual attenuation of the measured non-Newtonian fluid, the irradiation volume of the β-ray and the mass absorption coefficient of the non-Newtonian fluid containing the gas;

[0014] S7. The time of the measured non-Newtonian fluid passing through the measuring chamber is measured, and the mass flow of the measured non-Newtonian fluid is calculated according to the density of the measured non-Newtonian fluid, the field flow rate of the measured non-Newtonian fluid, the cross-sectional area of the measuring chamber and the time of the measured non-Newtonian fluid passing through the measuring chamber.

[0015] Further, the calculation formula of the temperature variation coefficient of the gas is:

[0016]

[0017] wherein I 气1 is the residual attenuation of the gas measured at the temperature of T1, I 气2 is the residual attenuation of the gas measured at the temperature of T2, I 气1 and I气2 I0(P1) and I0(P2) are the residual attenuations of the gas measured at the same temperature and in the same measuring chamber with the flow rate being 0 and the pressure being P1 and P2 respectively;

[0018] The formula for calculating the pressure variation coefficient is:

[0019]

[0020] I0(P1) and I0(P2) are the residual attenuations of the gas measured at the same temperature and in the same measuring chamber with the flow rate being 0 and the pressure being P1 and P2 respectively; 气3 I0(P1) and I0(P2) are the residual attenuations of the gas measured at the same temperature and in the same measuring chamber with the flow rate being 0 and the pressure being P1 and P2 respectively; 气4 I0(P1) and I0(P2) are the residual attenuations of the gas measured at the same temperature and in the same measuring chamber with the flow rate being 0 and the pressure being P1 and P2 respectively; 气3 I0(P1) and I0(P2) are the residual attenuations of the gas measured at the same temperature and in the same measuring chamber with the flow rate being 0 and the pressure being P1 and P2 respectively; 气4 I0(P1) and I0(P2) are the residual attenuations of the gas measured at the same temperature and in the same measuring chamber with the flow rate being 0 and the pressure being P1 and P2 respectively;

[0021] The formula for calculating the pressure variation coefficient is:

[0022]

[0023] I0(P1) and I0(P2) are the residual attenuations of the gas measured at the same temperature and in the same measuring chamber with the flow rate being 0 and the pressure being P1 and P2 respectively; 定1 I0(P1) and I0(P2) are the residual attenuations of the gas measured at the same temperature and in the same measuring chamber with the flow rate being 0 and the pressure being P1 and P2 respectively; 动1 I0(P1) and I0(P2) are the residual attenuations of the gas measured at the same temperature and in the same measuring chamber with the flow rate being 0 and the pressure being P1 and P2 respectively; 定1 I0(P1) and I0(P2) are the residual attenuations of the gas measured at the same temperature and in the same measuring chamber with the flow rate being 0 and the pressure being P1 and P2 respectively; 动1 I0(P1) and I0(P2) are the residual attenuations of the gas measured at the same temperature and in the same measuring chamber with the flow rate being 0 and the pressure being P1 and P2 respectively.

[0024] Further, the specific way of calculating the residual attenuation of the gas at the set speed in step S4 is:

[0025] S4a-1. According to the set pressure P 设 , the set temperature T 设 , the temperature variation coefficient K T , the pressure variation coefficient K P , the standard pressure P 定 , the normal temperature T 定 , and the residual attenuation of the gas I 定 under the standard pressure and the normal temperature, the residual attenuation of the gas I 设 under the set pressure and the set temperature and with the flow rate being 0 is calculated:

[0026] S4a-2. According to the set speed u 设 , the flow rate variation coefficient K u , and the residual attenuation of the gas I 设 under the set pressure and the set temperature and with the flow rate being 0, the residual attenuation of the gas I 动2 at the set speed is calculated:

[0027] Further, in step S4, the mass absorption coefficient μ of the non-Newtonian fluid containing gas is calculated. m动 The specific method is as follows:

[0028]

[0029] Where n is the number of times the residual decay of the non-Newtonian fluid is measured, u 设i For the i-th set speed, ρ 动1 For the concentration of a non-Newtonian fluid, I 动2i Let I be the remaining decay amount of the gas at the set velocity in the i-th iteration. 2i denoted as the remaining decay amount of the non-Newtonian fluid in the i-th iteration.

[0030] Further, in step S5, the remaining attenuation of the flowing gas under the on-site environment is calculated:

[0031] S5a-1. Measurement at standard atmospheric pressure P 定 and room temperature T 定 At a gas flow rate of 0, the remaining attenuation I of β rays passing through the gas is... 定 ;

[0032] S5a-2. Based on the ambient temperature T 现 On-site pressure P 现 Temperature variation coefficient K T and pressure variation coefficient K P Calculate the residual attenuation I of the gas when the gas velocity is 0 under the on-site environment. 现 :

[0033]

[0034] Among them, I 定 The residual decay of the non-Newtonian fluid being measured was obtained in a measuring chamber of the same diameter, P. 定 For standard pressure, T 定 At room temperature, I 定 The remaining attenuation of the gas under standard pressure, room temperature, and zero flow rate conditions;

[0035] S5a-3. Based on the residual attenuation I of the gas when the gas flow rate is 0 under the on-site environment. 现 The in-situ flow velocity u of the non-Newtonian fluid being measured 现 and the velocity variation coefficient K u Calculate the remaining attenuation I of the flowing gas under the on-site environment. 动3 :

[0036] Furthermore, the density ρ of the non-Newtonian fluid being measured动2 for:

[0037]

[0038] Where I2 is the residual decay of the non-Newtonian fluid being measured. Where D is the diameter of the pipe in the measuring chamber, and L is the irradiation length of the beta rays.

[0039] Furthermore, the mass flow rate Q of the non-Newtonian fluid being measured m for:

[0040] Q m =ρ 动2 ×u 现 ×A×t

[0041] Where, ρ 动2 Let A be the density of the non-Newtonian fluid being measured, A be the cross-sectional area of ​​the measuring chamber, and t be the time it takes for the fluid in the pipe to pass through the measuring chamber.

[0042] The method of measuring multiphase flow using beta rays can directly measure the mass flow rate without conversion, providing accurate flow rate. Moreover, the measurement process takes into account complex measurement environments and operating conditions, fully considering the influence of temperature, pressure, and flow velocity on the measurement results of multiphase fluids, and reducing the impact of environmental parameters on the results of directly measured volumetric flow rate.

[0043] This invention experimentally calculates the effects of temperature, pressure, and flow rate on beta rays. Based on these effects and the residual attenuation of gas at room temperature and standard pressure, it calculates the residual attenuation of gas under the measurement environment. Furthermore, by measuring the residual attenuation of beta rays through a non-Newtonian fluid, the concentration of the non-Newtonian fluid is calculated, thus accurately determining the cumulative mass flow rate of the gas-solid mixture. The purpose of this invention is to utilize the attenuation principle of beta rays to measure important parameters of multiphase flow mixtures under operating conditions. It effectively combines knowledge of fluid mechanics and thermodynamics to comprehensively adapt to complex operating conditions and measurement environments of multiphase flows. Attached Figure Description

[0044] Figure 1 This is a schematic diagram of measuring the residual decay of a substance using beta rays.

[0045] Figure 2 It is a graph showing the attenuation of beta rays in a gas.

[0046] Figure 3 This is a diagram illustrating the principle of β-ray attenuation separation.

[0047] Figure 4 This is a structural diagram showing the flow of a non-Newtonian fluid in a measuring chamber. Detailed Implementation

[0048] The present invention will now be described in further detail.

[0049] This invention provides a method for measuring the flow rate of multiphase flow using beta rays, comprising the following steps:

[0050] S1. Under constant pressure, measure the residual attenuation of β rays passing through a gas with a flow rate of 0 at at least two different temperatures; calculate the temperature change coefficient based on the residual attenuation under different temperature conditions.

[0051] Crude oil is a typical multiphase flow and is a non-Newtonian fluid, often considered a mixture of liquid and solid. Formulas derived from Newtonian fluids are unsuitable for non-Newtonian fluids; therefore, in this invention, non-Newtonian fluids are treated as solids. This invention utilizes the attenuation principle of beta rays to measure important parameters of non-Newtonian fluids containing gas under operating conditions, such as the specific gravity and flow rate of the gaseous, solid, or liquid states. By combining knowledge of fluid mechanics and thermodynamics, it comprehensively adapts to the complex operating conditions and measurement environments of multiphase flows.

[0052] like Figure 1 As shown, multiphase flow passes through the measuring chamber, which is cylindrical and can be connected to pipelines in the field environment. The emission chamber emits beta rays, and the detection chamber collects the beta rays. Flanges are installed to connect the measuring chamber to the emission chamber and the detection chamber respectively. Protective covers are installed on the outside of the emission chamber and the detection chamber.

[0053] Among the parameters that need to be measured during flow measurement, the most important are mass flow rate and volumetric flow rate. Mass flow rate is the mass of fluid flowing through a pipe or open channel per unit time, measured in kg / s (kilograms per second) or t / h (tons per hour). The integral of mass flow rate over time is the cumulative mass flow rate, measured in kg (kilograms) or t (tons). Volumetric flow rate is the volume of fluid flowing through a pipe or open channel per unit time, measured in m³. 3 / s (cubic meters per second) or m 3 / h (cubic meters per hour). The integral of volumetric flow rate over time is the volumetric volumetric flow rate, with units of m³. 3 (cubic meter). A derived unit in the International System of Units (SI).

[0054] Since volumetric flow rate varies with fluid density, and fluid density changes with fluid temperature and pressure, the fluid temperature and pressure must be given along with the volumetric flow rate (or accumulated volumetric flow rate). For ease of comparison, the volumetric flow rate is sometimes converted to the volumetric flow rate under standard conditions (or accumulated volumetric flow rate under standard conditions), referred to as standard volumetric flow rate. The standard conditions referred to in this invention are a pressure of one atmosphere (101 kPa or 760 mmHg) and a temperature of 25°C.

[0055] The conversion relationship between mass flow and volume flow is as follows:

[0056] q m = p h · q v (1)

[0057] Q m = p h · Q v = q m · t = p h · q v · t (2)

[0058] Where q m is the instantaneous mass flow, Q m is the cumulative mass flow, q v is the instantaneous volume flow, Q v is the cumulative volume flow, t is the cumulative time, p h is the average density of the mixed fluid for multiphase flow.

[0059] However, it is difficult to determine the density p of multiphase flow at the beginning, so other parameters are measured first, and p is calculated at last. The single-phase flow of ideal gas or liquid is considered as incompressible fluid, and since the volume is arbitrary and the integrated function is continuous, there is formula (3).

[0060]

[0061] Such fluid can be calculated by formula (4) and (5) in the pipe under steady flow condition since the density p is constant.

[0062]

[0063] q v = u · A (5)

[0064] As long as the cross-sectional average flow rate u is known, the pipe diameter can be measured to be D, so the cross-sectional area A of the flow measuring instrument installed in the pipe can be obtained by formula (4), the instantaneous volume flow formula can be calculated by formula (5), and the cumulative volume flow is obtained.

[0065] For multiphase flow, p changes with time, as shown in formula (6).

[0066]

[0067] Therefore, to obtain the cumulative effective quantity calibration of the multiphase flow, the mass M is used as the quantity calibration, for example, how many tons of crude oil in the oil calibration, or the volume calibration of the single fluid formed in the container, such as a barrel of crude oil. If the two-phase flow is formed in the crude oil transportation, such as the gas-solid two-phase flow, the fluid calculation formula of the liquid is not applicable due to the large viscosity of the crude oil, so the solid can be considered. The mass of the gas and the mass of the solid are obtained in real time, and the quantity calibration and pricing are performed.

[0068] Since the ρ of the crude oil changes with time when the crude oil moves in the pipeline, the mass of the gas and the mass of the solid cannot be obtained by weighing, and the traditional flow measurement instrument cannot be used, such as the differential pressure method, the turbine method, and the electromagnetic method, which are difficult to accurately measure the flow of the fluid. Therefore, the method of measuring the content of the solid particles in the gas by the β-ray can be used.

[0069] Under the condition that the gas flow rate is 0 and the pressure is constant, the temperature is changed to obtain the residual attenuation of the gas at different temperatures. According to the residual attenuation of the gas at different temperatures, the relationship between the residual attenuation and the temperature is determined.

[0070]

[0071] The residual attenuation is the amount of residual rays of the β-ray after passing through the substance.

[0072] The temperature can be changed by heating or cooling.

[0073] The calculation formula of the temperature change coefficient is obtained.

[0074]

[0075] Wherein, I 气1 is the residual attenuation of the gas measured at the temperature T1, I 气2 is the residual attenuation of the gas measured at the temperature T2, I 气1 and I 气2 are the residual attenuations measured at the flow rate of 0 and the same pressure and diameter in the measurement chamber.

[0076] S2. Under the condition that the temperature is constant, the residual attenuation of the β-ray passing through the gas with the flow rate of 0 is measured at least at two different pressures. According to the residual attenuation at different pressures, the pressure change coefficient is calculated.

[0077] Under the condition that the gas flow rate is 0 and the temperature is constant, the pressure is changed to obtain the residual attenuation of the gas at different pressures. According to the residual attenuation of the gas at different pressures, the relationship between the residual attenuation and the pressure is determined.

[0078]

[0079] The calculation formula of the pressure variation coefficient is:

[0080]

[0081] wherein, I 气3 is the residual attenuation of the gas measured at the pressure P1, I 气4 is the residual attenuation of the gas measured at the pressure P2. 气3 and I 气4 are the residual attenuations measured at the same temperature and in the same diameter measuring chamber with the flow rate being 0.

[0082] The pressure can be changed by a booster pump.

[0083] Similarly, the temperature and the pressure are changed simultaneously at the flow rate of the gas being 0, the residual attenuation of the gas under the simultaneous change of the temperature and the pressure is obtained, and the relationship between the residual attenuation and the temperature and the pressure is determined:

[0084]

[0085] wherein, I 气5 is the residual attenuation measured at the pressure P1 and the temperature T1, I 气6 is the residual attenuation measured at the pressure P2 and the temperature T2.

[0086] S3. The residual attenuations of the β-ray passing through the gas at at least two different flow rates are measured respectively under the condition that the temperature and the pressure are constant; and the flow rate variation coefficient is calculated according to the residual attenuations at different flow rates.

[0087] Under the condition that the pressure and the temperature are constant, the flow rate of the gas is changed constantly, the residual attenuations of the gas at different flow rates are obtained, and the relationship between the residual attenuation and the flow rate of the gas is determined according to the residual attenuations of the gas at different flow rates:

[0088]

[0089] The calculation formula of the flow rate variation coefficient is:

[0090]

[0091] wherein, I 定1 is the residual attenuation of the gas measured at the flow rate being 0, I 动1 is the residual attenuation of the gas measured at the flow rate u1, I 定1 and I 动1 are the residual attenuations measured at the same temperature and pressure and in the same diameter measuring chamber.

[0092] In the present application, the gas flow rate is obtained by a speed sensor.

[0093] S4. Under the condition of set pressure and set temperature, let a certain amount of non-Newtonian fluid flow in the measuring chamber at a set speed, and the non-Newtonian fluid does not fill the cross section of the measuring chamber during the flow process, measure the residual attenuation of the β-ray passing through the non-Newtonian fluid, and calculate the residual attenuation of the β-ray passing through the gas at the set speed according to the set pressure and the set temperature; change the set speed at least 10 times to obtain the residual attenuation of the non-Newtonian fluid and the residual attenuation of the gas at least 10 times, and calculate the mass absorption coefficient of the non-Newtonian fluid containing the gas according to the measured residual attenuation of the gas and the residual attenuation of the non-Newtonian fluid each time.

[0094] When the non-Newtonian fluid does not fill the cross section of the measuring chamber during the flow process, there is air, which is closer to the flow condition of the non-Newtonian fluid in the real environment.

[0095] First, the concentration of the non-Newtonian fluid containing the gas is measured by β-ray. When the β-ray passes through a certain mass of material, the intensity of the ray will attenuate. The β-ray entering the material consumes energy through ionization loss and radiation loss, and after the energy is exhausted, it stays in the material and is absorbed by the material. When the energy is not exhausted, the β-ray passing through the material will attenuate. When the length and width of the space are taken, the relationship between the mass of the material and the residual attenuation of the β-ray after passing through the material conforms to formula (14).

[0096]

[0097] Wherein, I0 is the initial β-ray radiation, I is the residual attenuation after passing through the solid, m is the material being radiated, μ m is the mass absorption coefficient, also known as the mass attenuation coefficient. The attenuation coefficients of different forms of materials are different, but as the atomic number increases, μ m changes very little, so the average value obtained by multiple experiments can be treated as a constant.

[0098] Formula (14) is the attenuation equation of the β-ray passing through the solid. When the β-ray passes through the gas, it will be different. When the β-ray attenuates in the gaseous material, I 气0 is not the initial value, because I 气0 has already passed through the gaseous material and attenuated, which is denoted as I 气7 , and the second measurement continues to attenuate, which is denoted as I 气8 .

[0099] As shown in Figure 2 , in order to measure the value of I, the position of I 气7 and the position of I 气8Position two acquisition probes, namely using different diameter measuring chamber to measure the remaining attenuation, can calculate I 气7 and I 气8 The change relationship between I 气7 and I 气8 The attenuation formula of different mass m1 and m2 of gas through the gas is shown in formula (15) (the greater I, the smaller the attenuation, the greater I, the smaller m).

[0100]

[0101] Where, I 气7 is the remaining attenuation of the gas with mass m 气1 , I 气8 is the remaining attenuation of the gas with mass m 气2 , I 气7 and I 气8 are measured in different diameter measuring chambers.

[0102] To solve the problem of measuring non-Newtonian fluid containing gas in multiphase flow, it is necessary to comprehensively use the attenuation formula of β-ray in non-Newtonian fluid material and the attenuation formula in gas Commonly derived calculation formula, multi-parameter composite formula is used to calculate, which can measure the flow, concentration and mass of non-Newtonian fluid containing gas.

[0103] To measure multiphase flow by β-ray method, it is necessary to eliminate the influence of β-ray attenuation in gas material on the calculation of non-Newtonian fluid concentration, and to separate the attenuation of β-ray in non-Newtonian fluid. When β-ray passes through two-phase mixture, it causes two attenuation, I 气衰 in gas and I 非衰 in non-Newtonian fluid, which need to be separated in calculation.

[0104] As shown in Figure 3 , the left graph is the measurement graph of β-ray passing through gas, and the right graph is the measurement graph of β-ray passing through non-Newtonian fluid containing gas. When β-ray passes through multiphase flow containing gas in non-Newtonian fluid, the loss of β-ray is considered respectively, I 非衰 can be expressed as I 非衰 =I1-I2, and its natural logarithm relationship can be expressed as formula (16).

[0105]

[0106] By substituting the solid formula and the formula M=ρ×V into formula (16), formula (17) can be obtained.

[0107]

[0108] In formula (17), V is the volume of the β-ray radiating gas, μ m I1 is the mass absorption coefficient of particulate matter in the gas, I2 is the residual attenuation of beta rays passing through the gas, and ρ is the average concentration of the non-Newtonian fluid containing the gas. I2 can be directly measured, while I1 cannot be directly obtained from gas measurements alone and requires further calculation.

[0109] According to formula (18), the mass absorption coefficient μ can be obtained. m The expression:

[0110]

[0111] The mass absorption coefficient can be obtained through multiple experiments, and I1 and I2 in formula (18) can both be the residual attenuation measured when the gas flow rate is 0 or when the gas is flowing.

[0112] First, in a laboratory setting, with a gas flow rate of 0, pressure and temperature are measured, and I1 is calculated according to formula (11). In a non-Newtonian fluid measurement chamber, I2 is directly measured, and the density ρ can be determined based on... The calculations show that by changing the volume of the non-Newtonian fluid at least 10 times, the values ​​of I1 and I2 for each change are obtained.

[0113] When the gas velocity in the measuring chamber is 0, the gas temperature and pressure need to be measured, and then the value of I1 can be determined according to formula (11). In formula (11), I1 and I 气6 For the same working conditions, the equivalent relationship is to be determined in advance. Other unknowns in formula (11) need to be calculated in advance. 气5 Measurements can be performed at standard atmospheric pressure and room temperature.

[0114] By placing different volumes of the same non-Newtonian fluid in the measuring chamber, and through repeatable experiments, μ m It is a fundamentally unchanging value, which can be considered a constant. It is determined by the average of multiple measurements, thus yielding μ. m .

[0115] For a non-Newtonian fluid that is flowing and contains gas, μ of the non-Newtonian fluid that is flowing and contains gas... m μ of a non-Newtonian fluid with a velocity of 0 and containing gas m Not quite the same. Therefore, the μ of a flowing, non-Newtonian fluid containing gas... m The mass absorption coefficient μ is related to velocity, therefore it is also related to the velocity of the flowing, non-Newtonian fluid containing gas.m动 The calculation formula is:

[0116]

[0117] like Figure 4 As shown, using Figure 4 The device enables the setting of the flow velocity for non-Newtonian fluids. Figure 4 The device also enables the circulation of substances flowing within the measuring apparatus. A fluid recovery tank recovers the fluid after the experiment, and then a circulation pump returns it to the extension tank, which is typically located at a higher elevation. The fluid extension tank has potential energy at a height h, which is converted into kinetic energy, i.e., velocity. This velocity is relatively low, so a speed-regulating extension pump is added to increase the head and regulate the flow rate. An intermediate flow velocity sensor measures the flow velocity, and a regulating switch between the speed-regulating extension pump and the flow velocity sensor adjusts the flow rate. Figure 4 The adjacent devices are connected by pipes, and formulas (20)-(22) require this device to be tested.

[0118] The specific method for calculating the remaining attenuation of β rays passing through the gas at a given velocity is as follows:

[0119] S4a-1. Based on the set pressure P 设 Set temperature T 设 Temperature variation coefficient K T Pressure variation coefficient K P Standard pressure P 定 , room temperature T 定 And the residual decay I of the gas under standard pressure and room temperature conditions. 定 Set pressure P 设 Set temperature T 设 Temperature variation coefficient K T Pressure variation coefficient K P Standard pressure P 定 , room temperature T 定 And the residual decay I of the gas under standard pressure, room temperature, and zero flow rate conditions. 定 Substituting into formula (11), calculate the residual decay I of the gas under the conditions of set pressure, set temperature, and zero flow rate. 设 :

[0120]

[0121] The standard pressure is 101 kPa and the room temperature is 25°C.

[0122] S4a-2. Based on the set speed u 设 Flow velocity variation coefficient K u The residual decay amount I of the gas under the conditions of set pressure, set temperature, and flow rate of 0.设 , calculate the residual attenuation I of the gas at the set speed 动2 :

[0123]

[0124] Calculate the mass absorption coefficient μ of the non-Newtonian fluid containing the gas m动 The specific way is:

[0125]

[0126] Wherein, n is the number of times of measuring the residual attenuation of the non-Newtonian fluid, u 设i is the set speed of the i-th, ρ 动1 is the known concentration of the non-Newtonian fluid, I 动2i is the residual attenuation of the gas at the i-th set speed, I 2i is the residual attenuation of the i-th non-Newtonian fluid, and V is the volume of the β-ray radiated gas.

[0127] ρ 动1 is obtained by using the volume of the non-Newtonian fluid and the volume of the β-ray radiated gas.

[0128] S5. When measuring the mass flow of the measured non-Newtonian fluid in the field environment, the field flow rate, field pressure and field temperature of the measured non-Newtonian fluid are measured, and the residual attenuation of the flowing gas in the field environment is calculated according to the temperature variation coefficient, the pressure variation coefficient, the flow rate variation coefficient, the field flow rate, the field pressure and the field temperature of the measured non-Newtonian fluid.

[0129] At least two flow rate sensors are arranged at the pipeline, and the field flow rate of the measured non-Newtonian fluid is measured by using the multi-point measurement method. The field flow rate of the measured non-Newtonian fluid is the average of all flow rate sensors. In the field environment, when the measured non-Newtonian fluid is transmitted in the pipeline, there is air, so in practical application, the measured non-Newtonian fluid contains air.

[0130] S5a-1. Measure the residual attenuation I 定 of the gas when the gas flow rate is 0 at the standard atmospheric pressure P 定 and the normal temperature T 定 .

[0131] The field temperature T 现 , the field pressure P 现 , the temperature variation coefficient K T , the pressure variation coefficient K P , the standard atmospheric pressure P 定 , the normal temperature T 定 , and the residual attenuation I 定 of the gas at the standard atmospheric pressure P 定and the remaining attenuation of the gas when the gas flow rate is 0 under the field environment I 定 is substituted into equation (11).

[0132] S5a-2. According to the field temperature T 现 , the field pressure P 现 , the temperature variation coefficient K T and the pressure variation coefficient K P , the remaining attenuation of the gas when the gas flow rate is 0 under the field environment I 现 is calculated.

[0133]

[0134] wherein I 定 is the remaining attenuation of the measured non-Newtonian fluid, P 定 is the standard pressure, T 定 is the normal temperature, and I 定 is the remaining attenuation of the gas when the gas flow rate is 0 under the standard pressure and the normal temperature.

[0135] S5a-3. According to the remaining attenuation of the gas when the gas flow rate is 0 under the field environment I 现 , the field flow rate of the measured non-Newtonian fluid u 现 and the flow rate variation coefficient K u , the remaining attenuation of the field gas when the gas flows under the field environment, and the remaining attenuation of the flowing gas without the non-Newtonian fluid under the field condition I 动3 is calculated.

[0136]

[0137] S6. The remaining attenuation of the measured non-Newtonian fluid under the field environment is measured, and according to the remaining attenuation of the flowing gas under the field environment, the remaining attenuation of the measured non-Newtonian fluid, the irradiation volume of the β-ray and the mass absorption coefficient of the non-Newtonian fluid containing the gas, the density of the measured non-Newtonian fluid is calculated:

[0138]

[0139] wherein I3 is the remaining attenuation of the measured non-Newtonian fluid, V is the volume of the gas irradiated by the β-ray, and V can be determined by the irradiation range of the β-ray of the flow measuring device, wherein D is the pipe diameter of the measuring chamber, and L is the irradiation length of the β-ray.

[0140] Finally, the density ρ 动2 of the measured non-Newtonian fluid is obtained, and then the cumulative mass flow rate Q m is obtained according to equations 1 and 2. mThe multiphase flow in the pipeline can be measured and charged, and the instantaneous mass flow q is calculated m The cumulative mass flow Q is calculated as shown in equation (26) m As shown in equation (27).

[0141] q m = p 动2 × u m动 × A (26)

[0142] S7. Measure the time of the measured non-Newtonian fluid passing through the measuring chamber, and calculate the mass flow of the measured non-Newtonian fluid according to the density of the measured non-Newtonian fluid, the on-site flow rate of the measured non-Newtonian fluid, the cross-sectional area of the measuring chamber, and the time of the measured non-Newtonian fluid passing through the measuring chamber:

[0143] Q m = p 动2 × u 现 × A × t (27)

[0144] Where p 动2 is the density of the measured non-Newtonian fluid, A is the cross-sectional area of the measuring chamber, and t is the time of the fluid in the pipeline passing through the measuring chamber.

[0145] As shown in Table 1, at a laboratory temperature of 25°C, the temperature of the heated measuring chamber is 34°C measured by a temperature sensor, the gas flow rate is controlled at 2m / s, the measuring chamber pipe diameter D is 200mm, and the standard source is 137C S , the value of I 动3 is calculated without non-Newtonian fluid, which is 1.415MeV. In the experiment, different amounts of crude oil are added to the measuring chamber, and the value of I3 is measured at different proportions of crude oil in the overall measuring device. The value of u m is determined, and the obtained data is calculated according to the above formula.

[0146] Table 1. Laboratory measurement data table

[0147]

Claims

1. A method for measuring multiphase flow rate using beta rays, characterized in that, Includes the following steps: S1. Under constant pressure, measure the residual attenuation of β rays passing through a gas with a flow rate of 0 at at least two different temperatures; calculate the temperature change coefficient based on the residual attenuation under different temperature conditions. S2. Under constant temperature conditions, measure the residual attenuation of β rays passing through a gas with a flow velocity of 0 under at least two different pressure conditions; calculate the pressure variation coefficient based on the residual attenuation under different pressure conditions. S3. Under constant temperature and pressure, measure the residual attenuation of β rays passing through the gas under at least two different flow rates; calculate the flow rate variation coefficient based on the residual attenuation under different flow rates. S4. Under set pressure and set temperature conditions, a certain amount of non-Newtonian fluid is placed into the measuring chamber and flows at a set speed, and the non-Newtonian fluid does not fill the cross section of the measuring chamber during the flow. The residual attenuation of β rays passing through the non-Newtonian fluid is measured, and the residual attenuation of β rays passing through the gas at the set speed is calculated according to the set pressure and set temperature. The set speed is changed at least 10 times to obtain the residual attenuation of the non-Newtonian fluid and the residual attenuation of the gas at least 10 times. Based on the residual attenuation of the gas and the residual attenuation of the non-Newtonian fluid measured each time, the mass absorption coefficient of the non-Newtonian fluid containing gas is calculated. S5. When measuring the mass flow rate of the non-Newtonian fluid under test in the field environment, measure the field velocity, field pressure and field temperature of the non-Newtonian fluid under test. Calculate the residual attenuation of the flowing gas under the field environment based on the temperature change coefficient, pressure change coefficient, velocity change coefficient, field velocity, field pressure and field temperature of the non-Newtonian fluid under test. S6. Measure the residual decay of the non-Newtonian fluid under test in the field environment. Calculate the density of the non-Newtonian fluid under test based on the residual decay of the flowing gas in the field environment, the residual decay of the non-Newtonian fluid under test, the irradiation volume of β rays, and the mass absorption coefficient of the non-Newtonian fluid containing gas. S7. Measure the time it takes for the non-Newtonian fluid to pass through the measuring chamber. Calculate the mass flow rate of the non-Newtonian fluid based on its density, velocity, cross-sectional area, and the time it takes for the fluid to pass through the chamber.

2. The method for measuring multiphase flow rate using β-rays according to claim 1, characterized in that, The formula for calculating the coefficient of temperature change of a gas is: Among them, I 气1 I represents the residual decay of the gas measured at temperature T1. 气2 I represents the residual decay of the gas measured at temperature T2. 气1 and I 气2 All of these are residual attenuation measurements taken at a flow rate of 0 and under the same pressure and diameter in measuring chambers. The formula for calculating the pressure change coefficient is: Among them, I 气3 I represents the residual decay of the gas measured at pressure P1. 气4 I represents the residual decay of the gas measured at pressure P2. 气3 and I 气4 All of these are residual attenuation measurements taken at a flow rate of 0 and in the same temperature and diameter measurement chamber. The formula for calculating the velocity variation coefficient is: Among them, I 定1 I is the residual attenuation of the gas measured when the gas flow rate is 0. 动1 I is the residual attenuation of the gas measured at a gas flow rate of u1. 定1 and I 动1 The remaining attenuation was measured at the same temperature and pressure, and in a measuring chamber with the same diameter.

3. The method for measuring multiphase flow rate using β-rays according to claim 1, characterized in that, The specific method for calculating the remaining attenuation of the gas at the set velocity in step S4 is as follows: S4a-1. Based on the set pressure P 设 Set temperature T 设 Temperature variation coefficient K T Pressure variation coefficient K P Standard pressure P 定 , room temperature T 定 And the residual decay I of the gas under standard pressure and room temperature conditions. 定 Calculate the residual decay I of the gas under the conditions of set pressure, set temperature, and zero flow rate. 设 : S4a-2. Based on the set speed u 设 Flow velocity variation coefficient K u The residual decay amount I of the gas under the conditions of set pressure, set temperature, and flow rate of 0. 设 Calculate the remaining decay amount I of the gas at the set velocity. 动2 :

4. The method for measuring multiphase flow rate using β-rays according to claim 1, characterized in that, In step S4, the mass absorption coefficient μ of the non-Newtonian fluid containing gas is calculated. m动 The specific method is as follows: Where n is the number of times the residual decay of the non-Newtonian fluid is measured, u 设i For the i-th set speed, ρ 动1 For the concentration of a non-Newtonian fluid, I 动2i Let I be the remaining decay amount of the gas at the set velocity in the i-th iteration. 2i denoted as the remaining decay amount of the non-Newtonian fluid in the i-th iteration.

5. The method for measuring multiphase flow rate using β-rays according to claim 1, characterized in that, Step S5 calculates the remaining attenuation of the flowing gas under the on-site environment: S5a-1. Measurement at standard atmospheric pressure P 定 and room temperature T 定 At a gas flow rate of 0, the remaining attenuation I of β rays passing through the gas is... 定 ; S5a-2. Based on the ambient temperature T 现 On-site pressure P 现 Temperature variation coefficient K T and pressure variation coefficient K P Calculate the residual attenuation I of the gas when the gas velocity is 0 under the on-site environment. 现 : Among them, I 定 The residual decay of the non-Newtonian fluid being measured was obtained in a measuring chamber of the same diameter, P. 定 For standard pressure, T 定 At room temperature, I 定 The remaining attenuation of the gas under standard pressure, room temperature, and zero flow rate conditions; S5a-3. Based on the residual attenuation I of the gas when the gas flow rate is 0 under the on-site environment. 现 The in-situ flow velocity u of the non-Newtonian fluid being measured 现 and the velocity variation coefficient K u Calculate the remaining attenuation I of the flowing gas under the on-site environment. 动3 :

6. The method for measuring multiphase flow rate using β-rays according to claim 5, characterized in that, The density ρ of the non-Newtonian fluid being measured 动2 for: Where I3 represents the residual decay of the non-Newtonian fluid being measured. Where D is the diameter of the pipe in the measuring chamber, and L is the irradiation length of the beta rays.

7. The method for measuring multiphase flow rate using β-rays according to claim 6, characterized in that, The mass flow rate Q of the non-Newtonian fluid being measured m for: Q m =ρ 动2 ×u 现 ×A×t Where, ρ 动2 For the density of the non-Newtonian fluid being measured, u 现 Let A be the on-site flow velocity of the non-Newtonian fluid being measured, A be the cross-sectional area of ​​the measuring chamber, and t be the time it takes for the fluid in the pipe to pass through the measuring chamber.

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