Two-phase flow gas phase volume fraction measuring device and method

Abstract

The invention relates to the technical field of two-phase flow measurement, and provides a two-phase flow gas phase volume fraction measurement device and method, and the two-phase flow gas phase volume fraction measurement device, the two-phase flow gas phase volume fraction measurement device comprises: a measurement pipeline, the measurement pipeline comprises a first inlet and a second inlet, the first inlet is used for the inflow of a to-be-measured two-phase flow, and the second inlet is used for the inflow of a two-phase flow with a preset gas phase volume fraction; the pore plate is arranged in the measuring pipeline, one side of the pore plate faces the first inlet and the second inlet to form an incident flow side, and the other opposite side of the pore plate forms a back flow side; the pressure difference sensor is suitable for measuring the pressure difference between the incident flow side and the back flow side; the data acquisition module is suitable for acquiring the flow and density of the two-phase flow in the measuring pipeline; through the arrangement, the device is simpler, equipment with harsh use conditions or high cost, such as a capacitance analyzer, an imaging holdup analyzer and a ray attenuation analyzer, is prevented from being used, the application range is wider, and the device is safe, environment-friendly and low in cost.

Description

Technical Field

[0001] The present invention relates to the technical field of two-phase flow measurement, and in particular to a device and method for measuring the gas-phase holdup of two-phase flow. Background Art

[0002] Gas-liquid two-phase flow is often involved in fields such as petrochemical industry and cryogenic liquids. At present, the measurement methods of gas-liquid two-phase flow mainly include separation metering and non-separation metering. Separation metering is to separate the gas phase and the liquid phase by using a gas-liquid separator and then measure them separately. Non-separation metering is to directly measure with a gas-liquid two-phase flowmeter. Among them, the separation metering method has higher accuracy, but separation requires sufficient time, and the real-time performance is not good. In addition, the overall device is complex and the cost is high. The non-separation metering method has a small volume, low cost, convenient installation, wide application range, and has a broad application prospect.

[0003] In related technologies, non-separation metering usually uses a two-phase flowmeter in combination with a phase holdup meter. The two-phase flowmeter uses the assumption of uniform flow and regards the mixture as a single-phase fluid. Therefore, a certain type of rectifier needs to be installed in front of it to obtain uniform flow, and the structure is complex. At present, phase holdup measurement methods include density meters, capacitance, process tomography, ray attenuation, etc. The installation requirements of density meters are relatively high, and the use effect is not ideal. The capacitance analyzer has limited application conditions. The imaging holdup analyzer has high cost and complex equipment. The ray attenuation analyzer is restricted by many aspects such as safety and environmental protection.

[0004] Therefore, there is an urgent need for a two-phase flow gas-phase holdup measurement device with simple installation, small volume, wide application range, and low operation and maintenance costs. Summary of the Invention

[0005] The embodiments of the present invention provide a device and method for measuring the gas-phase holdup of two-phase flow, which are used to solve at least one of the technical problems existing in the prior art or related technologies, and have the advantages of simple installation, small volume, wide application range, and low operation and maintenance costs.

[0006] The present invention provides a device for measuring the gas-phase holdup of two-phase flow, including:

[0007] A measurement pipeline, including a first inlet and a second inlet. The first inlet is used for the two-phase flow to be measured to flow in, and the second inlet is used for the two-phase flow with a preset gas-phase holdup to flow in;

[0008] An orifice plate, arranged in the measurement pipeline. One side of the orifice plate faces the first inlet and the second inlet, forming a forward flow side, and the opposite side forms a backflow side;

[0009] A differential pressure sensor, arranged on the measurement pipeline and suitable for measuring the differential pressure between the forward flow side and the backflow side;

[0010] A data acquisition module is disposed on the measurement pipeline and is adapted to acquire the flow rate and density of the two-phase flow in the measurement pipeline.

[0011] According to a two-phase flow gas volume fraction measurement device provided by the present invention, the orifice plate includes a porous balance plate.

[0012] According to a two-phase flow gas volume fraction measurement device provided by the present invention, the data acquisition module includes a Coriolis flowmeter.

[0013] According to a two-phase flow gas volume fraction measurement device provided by the present invention, the data acquisition module is disposed near the backflow side of the orifice plate.

[0014] According to a two-phase flow gas volume fraction measurement device provided by the present invention, it further includes a two-phase flow module, and the two-phase flow module is connected to the second inlet and is adapted to provide two-phase flows with different preset gas volume fractions.

[0015] According to a two-phase flow gas volume fraction measurement device provided by the present invention, the two-phase flow module includes a liquid storage tank, a gas storage tank, a gas-liquid mixer, a first pump, and a second pump;

[0016] The liquid storage tank is connected to the gas-liquid mixer through the first pump and is adapted to pump a preset ratio of liquid into the gas-liquid mixer;

[0017] The gas storage tank is connected to the gas-liquid mixer through the second pump and is adapted to pump a preset ratio of gas into the gas-liquid mixer;

[0018] The gas-liquid mixer is used to mix the pumped liquid and gas to form a two-phase flow with a preset gas volume fraction, and the outlet of the gas-liquid mixer is connected to the second inlet.

[0019] According to a two-phase flow gas volume fraction measurement device provided by the present invention, a first valve is provided between the liquid storage tank and the gas-liquid mixer; and / or a second valve is provided between the gas storage tank and the gas-liquid mixer.

[0020] According to a two-phase flow gas volume fraction measurement device provided by the present invention, it further includes a two-phase flow pipeline, and the two-phase flow pipeline is connected to the first inlet of the measurement pipeline.

[0021] According to a two-phase flow gas volume fraction measurement device provided by the present invention, a three-way valve is connected to the end of the measurement pipeline, and the other two interfaces of the three-way valve are formed as the first inlet and the second inlet.

[0022] The present invention also provides a method for measuring the gas volume fraction of a two-phase flow, which is implemented by the above two-phase flow gas volume fraction measurement device and includes the following steps:

[0023] The two-phase flow with different preset gas volume fractions is introduced into the second inlet of the measured pipeline in batches;

[0024] The differential pressure sensors are used to collect the differential pressures on the upstream side and the downstream side of the orifice plate for each batch, and the data acquisition module is used to collect the flow rate and density of the two-phase flow at each preset gas volume fraction;

[0025] Based on the differential pressure data, flow rate data and density data collected for each batch, the discharge coefficient of the two-phase flow at different preset gas volume fractions is calculated through discrete experiments;

[0026] An association relationship formula between the discharge coefficient and the gas volume fraction is established;

[0027] The two-phase flow to be measured is introduced into the first inlet of the measured pipeline, the differential pressure sensors are used to collect the differential pressure on the upstream side and the downstream side of the orifice plate, and the data acquisition module is used to collect the flow rate and density of the two-phase flow to be measured;

[0028] Based on the differential pressure data, flow rate data and density data of the two-phase flow to be measured collected, the discharge coefficient of the two-phase flow to be measured is calculated, and the association relationship formula is applied to estimate the gas volume fraction of the two-phase flow to be measured.

[0029] According to a method for measuring the gas volume fraction of two-phase flow provided by the present invention, the discharge coefficient is calculated based on the following formula:

[0030]

[0031] where q v is the flow rate of the two-phase flow; β is the equivalent diameter ratio, which is the square root of the ratio of the orifice area of the orifice plate to the cross-sectional area of the measured pipeline; A is the cross-sectional area of the measured pipeline; ρ is the density of the two-phase flow; Δp is the differential pressure between the upstream side and the downstream side of the orifice plate.

[0032] According to a method for measuring the gas volume fraction of two-phase flow provided by the present invention, the establishment of the association relationship formula between the discharge coefficient and the gas volume fraction includes:

[0033] Based on the differential pressure data, flow rate data and density data collected for each batch, the average value of the discharge coefficients at different preset gas volume fractions is calculated

[0034] Based on the average value of the discharge coefficients The standard deviation sd of the discharge coefficients at different preset gas volume fractions is calculated C ;

[0035] An association relationship is established

[0036] In the formula, α is the gas volume fraction of the two-phase flow; λ1, λ2, γ1, γ2 are the coefficients of the relationship formula, which are determined by the least squares method;

[0037] The correlation coefficients R1 and R2 of the correlation relation are determined by the least squares method.

[0038] According to a gas volume fraction measurement method for two-phase flow provided by the present invention, the application of the correlation relation to estimate the gas volume fraction of the two-phase flow to be measured includes:

[0039] Calculate the estimated value α1,

[0040] Calculate the estimated value α2,

[0041] Calculate the average value R of the correlation coefficient,

[0042] Calculate the gas volume fraction α of the two-phase flow to be measured mea ,

[0043]

[0044] Beneficial effects:

[0045] According to a two-phase flow gas volume fraction measurement device and method provided by the present invention, during measurement, the first inlet is closed, and two-phase flows with different preset gas volume fractions are introduced into the measurement pipeline through the second inlet. The pressure difference between the upstream side and the downstream side of the orifice plate can be measured by a pressure difference sensor, the actual flow rate and density of the two-phase flow can be measured by a data acquisition module, the discharge coefficient of the two-phase flow with different preset gas volume fractions can be calculated according to the discharge coefficient formula, and then the correlation relation between the discharge coefficient and the gas volume fraction is established based on the different preset gas volume fractions and the calculated discharge coefficients. The coefficient and the correlation coefficient in the correlation relation are calculated by using the least squares method;

[0046] After obtaining the correlation relation, the first inlet is opened and the second inlet is closed. The two-phase flow to be measured is introduced into the measurement pipeline through the first inlet. By using the pressure difference measured by the pressure difference sensor and the actual flow rate and density of the two-phase flow measured by the data acquisition module, the discharge coefficient of the two-phase flow to be measured can be calculated, and then the discharge coefficient is substituted into the correlation relation to obtain the gas volume fraction of the two-phase flow to be measured. Compared with the related technology, the device is simpler, avoids using equipment with harsh operating conditions or high costs such as a capacitance analyzer, an imaging volume fraction analyzer, and a ray attenuation analyzer, has a wider application range, and is safe, environmentally friendly, and low-cost. Description of the Drawings

[0047] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0048] Figure 1 It is a schematic structural diagram of a two-phase flow gas holdup measuring device provided by an embodiment of the present invention;

[0049] Figure 2 It is one of the schematic structural diagrams of the cooperation between an orifice plate and a measuring pipeline provided by an embodiment of the present invention;

[0050] Figure 3 It is the second of the schematic structural diagrams of the cooperation between an orifice plate and a measuring pipeline provided by an embodiment of the present invention;

[0051] Figure 4 It is a flowchart of a two-phase flow gas holdup measuring method provided by an embodiment of the present invention.

[0052] Reference numerals:

[0053] 10. Measuring pipeline; 100. Three-way valve; 101. Pressure tapping hole; 11. Orifice plate; 12. Differential pressure sensor; 13. Data acquisition module; 14. Two-phase flow pipeline; 20. Two-phase flow module; 200. Liquid storage tank; 201. Gas storage tank; 202. Gas-liquid mixer; 203. First pump; 204. Second pump; 205. First valve; 206. Second valve. Detailed implementation manners

[0054] To make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions in the present invention will be clearly and completely described below with reference to the accompanying drawings in the present invention. Apparently, the described embodiments are some but not all of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art without making creative efforts based on the embodiments in the present invention belong to the scope of protection of the present invention.

[0055] To facilitate the understanding of the two-phase flow gas holdup measuring device and method provided by the present invention, its application background is first described. The measurement methods of gas-liquid two-phase flow mainly include two types: separated metering and non-separated metering. Although separated metering has relatively high accuracy, its real-time performance is poor, and the overall device is complex and costly. Relatively speaking, non-separated metering has advantages such as small volume, convenient installation, and wide application range, and has been widely used.

[0056] In the related art, non-separated metering usually uses a two-phase flowmeter in combination with a phase holdup meter. A rectifier needs to be installed in front of the two-phase flowmeter to obtain uniform flow, and the structure is complex. The phase holdup measurement includes methods such as density meters, capacitance, process tomography, and ray attenuation; the installation requirements of density meters are relatively high, and the use effect is not ideal; the capacitance analyzer has limited applicable conditions; the imaging holdup analyzer has high cost and complex equipment; the ray attenuation analyzer is restricted by multiple aspects such as safety and environmental protection.

[0057] Therefore, there is an urgent need for a measurement device to solve at least one of the above technical problems.

[0058] In actual work, it is found that the discharge coefficient is a main technical parameter of an orifice flowmeter, and its definition is the ratio of the actual flow rate to the ideal flow rate:

[0059]

[0060] where c1 and c2 are kinetic energy correction coefficients, which are related to the cross-sectional velocity distribution. For laminar flow, it takes 2, and for turbulent flow, it takes 1;

[0061] Ψ is the pressure-taking coefficient, which is related to the position of the minimum cross-sectional area of the flow beam and the actual pressure-taking position;

[0062] β is the equivalent diameter ratio, which is the square root of the ratio of the orifice area to the pipe cross-sectional area, and is only related to the orifice plate structure;

[0063] μ is the flow beam contraction coefficient, which is related to the orifice plate form and the Reynolds number Re;

[0064] ξ is the total orifice plate resistance coefficient, which is generally related to the orifice plate structure and Re.

[0065] For an orifice plate with a certain structure, when the pressure-taking method is determined, C is only related to Re. When Re reaches a certain level, the flow beam contraction coefficient and the total orifice plate resistance coefficient that affect C no longer change with Re. At this time, C is a constant that is almost independent of Re, and this region is the normal and stable working region of the flowmeter.

[0066] The above conclusion is not only applicable to single-phase fluids. Through numerical simulation, it is found that there is still a stable working region for gas-liquid two-phase flows, but two-phase flows with different gas volume fractions have different discharge coefficients C.

[0067] Therefore, for a specific structure of an orifice plate, when the pressure-taking method is fixed, there is a one-to-one correspondence between the discharge coefficient and the gas volume fraction in the two-phase flow within the stable working region.

[0068] Based on the above findings, the present invention provides a device and method for measuring the gas volume fraction in two-phase flows, which have the advantages of simple installation, small volume, wide application range, and low operation and maintenance costs.

[0069] The following combines Figures 1-4 to describe the device and method for measuring the gas volume fraction in two-phase flows of the present invention.

[0070] Refer to Figure 1, A two-phase flow gas holdup measurement device, comprising a measurement pipeline 10, an orifice plate 11, a differential pressure sensor 12, and a data acquisition module 13; wherein, the measurement pipeline 10 includes a first inlet and a second inlet, the first inlet is for the two-phase flow to be measured to flow in, and the second inlet is for the two-phase flow with a preset gas holdup to flow in; the orifice plate 11 is arranged inside the measurement pipeline 10, one side of the orifice plate 11 faces the first inlet and the second inlet, forming a flow-facing side, and the opposite side forms a flow-back side; the differential pressure sensor 12 is suitable for measuring the differential pressure between the flow-facing side and the flow-back side of the orifice plate 11; the data acquisition module 13 is suitable for acquiring the flow rate and density of the two-phase flow inside the measurement pipeline 10.

[0071] In practical applications, close the first inlet, and introduce two-phase flows with different preset gas holdups into the measurement pipeline 10 through the second inlet. The differential pressure between the flow-facing side and the flow-back side of the orifice plate 11 can be measured by the differential pressure sensor 12, the actual flow rate and density of the two-phase flow can be measured by the data acquisition module 13, the discharge coefficient of the two-phase flow with different preset gas holdups can be calculated according to the discharge coefficient formula, and then the correlation relationship between the discharge coefficient and the gas holdup can be established based on different preset gas holdups and the calculated discharge coefficients. The formula coefficients and correlation coefficients in the correlation relationship are calculated by using the least squares method.

[0072] After obtaining the correlation relationship, open the first inlet and close the second inlet, and introduce the two-phase flow to be measured into the measurement pipeline 10 through the first inlet. The discharge coefficient of the two-phase flow to be measured can be calculated by using the pressure difference measured by the differential pressure sensor 12 and the actual flow rate and density of the two-phase flow measured by the data acquisition module 13, and then the discharge coefficient is substituted into the correlation relationship to obtain the gas holdup of the two-phase flow to be measured. Compared with the related technology, the device is simpler, avoids using equipment with harsh operating conditions or high costs such as capacitance analyzers, imaging holdup analyzers, and ray attenuation analyzers, has a wider application range, and is safe, environmentally friendly, and low-cost.

[0073] Refer to Figure 1 , One end of the measurement pipeline 10 is connected with a three-way valve 100. One of the interfaces of the three-way valve 100 is connected to the measurement pipeline 10, and the other two interfaces form the above-mentioned first inlet and second inlet. The two-phase flow to be measured flows in through the first inlet, and the two-phase flow with a preset gas holdup flows in through the second inlet. In the flow direction of the two-phase flow, the orifice plate 11 is located downstream of the first inlet and the second inlet; according to actual requirements, the orifice plate 11 has various selectable forms and structures, and can be flexibly set according to actual requirements. In this embodiment, the orifice plate 11 adopts a porous balance plate, which has the characteristics of higher flow field stability and smaller pressure drop compared with a standard orifice plate, and can effectively prevent cavitation.

[0074] Refer to Figure 2 and Figure 3, there are two pressure tapping holes 101 provided on the measuring pipe 10. One of the pressure tapping holes 101 is close to the upstream side of the orifice plate 11, and the other pressure tapping hole 101 is close to the downstream side of the orifice plate 11. Moreover, the two pressure tapping holes 101 are symmetrically arranged with the orifice plate 11 as the center. The specific positions of the pressure tapping holes 101 can be set according to actual requirements; the two pressure tapping interfaces of the differential pressure sensor 12 are respectively connected to the two pressure tapping holes 101, and are used to collect the pressures on the upstream side and the downstream side of the orifice plate 11 respectively to obtain the differential pressure. When installing the differential pressure sensor 12, it needs to be installed in a direction perpendicular to the axis of the pipe, and during measurement, the pressure tapping interfaces of the differential pressure sensor 12 need to face downward to ensure the measurement accuracy of the differential pressure sensor 12.

[0075] Of course, the number and layout method of the pressure tapping holes 101 are not limited to the above. Based on different usage scenarios and requirements, the pressure tapping holes 101 can also be arranged in other ways. For example, in another embodiment, the number of pressure tapping holes 101 on each side of the orifice plate 11 is not limited to one. When the number of pressure tapping holes 101 on each side of the orifice plate 11 is greater than one, it is necessary to ensure that the pressure tapping positions are fixed during a single measurement, so as to reduce experimental errors and ensure measurement accuracy.

[0076] The differential pressure between the upstream side and the downstream side of the orifice plate 11 can be measured by the differential pressure sensor 12, and by combining the flow rate and density of the two-phase flow collected by the data acquisition module 13, the discharge coefficient of the two-phase flow can be calculated.

[0077] It can be understood that the data acquisition module 13 has a variety of selectable structures or forms, and can be flexibly configured specifically according to actual requirements as long as it can measure the flow rate and density of the two-phase flow.

[0078] In this embodiment, the data acquisition module 13 adopts a Coriolis flowmeter, and parameters such as the flow rate, temperature, and density of the two-phase flow can be measured by the Coriolis flowmeter.

[0079] Specifically, the Coriolis flowmeter is close to the downstream side of the orifice plate 11, that is, in the flow direction of the two-phase flow, the Coriolis flowmeter is located downstream of the orifice plate 11. With such a setting, the orifice plate 11 can act as a flow straightener to make the gas-liquid mixture of the two-phase flow more uniform and improve the reliability of the measurement by the Coriolis flowmeter.

[0080] Of course, in another embodiment, the Coriolis flowmeter can also be located upstream of the orifice plate 11, and the reliability of the measurement by the Coriolis flowmeter is ensured by setting a flow straightening element upstream of the Coriolis flowmeter.

[0081] In actual work, a two-phase flow with a preset gas volume fraction is introduced through the second inlet. The differential pressure sensor 12 can measure the differential pressure across the orifice plate 11, and the Coriolis flowmeter can measure parameters such as the flow rate and density of the two-phase flow. In this way, the discharge coefficient of the two-phase flow with the preset gas volume fraction can be measured, and the correlation relationship between the discharge coefficient and the gas volume fraction can be established, so as to estimate the gas volume fraction of the two-phase flow to be measured.

[0082] Refer to Figure 1 , a two-phase flow pipeline 14 is connected to the first inlet of the measurement pipeline 10, and the two-phase flow pipeline 14 is the flow pipeline of the two-phase flow to be measured; the second inlet of the measurement pipeline 10 is connected to the two-phase flow module 20, and the two-phase flow module 20 is used to provide two-phase flows with different preset gas volume fractions.

[0083] Specifically, the two-phase flow module 20 includes a liquid storage tank 200, a gas storage tank 201, a gas-liquid mixer 202, a first pump 203 and a second pump 204; wherein, the liquid storage tank 200 is used to store liquid, and the gas storage tank 201 is used to store gas; the liquid storage tank 200 is connected to the gas-liquid mixer 202 through the first pump 203, and is used to pump the liquid with a preset ratio into the gas-liquid mixer 202; the gas storage tank 201 is connected to the gas-liquid mixer 202 through the second pump 204, and is used to pump the gas with a preset ratio into the gas-liquid mixer 202; the gas-liquid mixer 202 is used to mix the pumped liquid and gas evenly to form a two-phase flow with a preset gas volume fraction, and the outlet of the gas-liquid mixer 202 is connected to the second inlet, and the two-phase flow with a preset ratio flows into the measurement pipeline 10 through the second inlet.

[0084] It should be noted that the specific structure of the gas-liquid mixer 202 can refer to the existing technology. However, since its specific structure is not the main inventive point of the present invention and its structure and principle are not improved in the present invention, the specific structure of the gas-liquid mixer 202 will not be described in detail.

[0085] Specifically, a first valve 205 is provided between the liquid storage tank 200 and the gas-liquid mixer 202, and a second valve 206 is provided between the gas storage tank 201 and the gas-liquid mixer 202; through the first pump 203 and the first valve 205, the second pump 204 and the second valve 206, the outflow volume of the liquid and the gas can be controlled, so as to form a two-phase flow with a preset gas volume fraction in the gas-liquid mixer 202.

[0086] It can be understood that the two-phase flow module 20 is not limited to the above-listed structure, and other structures of the two-phase flow module 20 as long as they can provide two-phase flows with a preset ratio are applicable.

[0087] The method for measuring the gas volume fraction of the two-phase flow provided by the present invention will be described below. The method for measuring the gas volume fraction of the two-phase flow described below can be mutually corresponded and referred to the device for measuring the gas volume fraction of the two-phase flow described above.

[0088] A method for measuring the gas volume fraction in two-phase flow, comprising the following steps:

[0089] S1. Inject two-phase flows with different preset gas volume fractions into the measurement pipeline 10 in batches through the second inlet;

[0090] Close the first inlet and open the second inlet. Through the cooperation of the first pump 203 and the first valve 205, and the second pump 204 and the second valve 206, pump different preset ratios of liquid and gas into the gas-liquid mixer 202. The liquid and gas are mixed in the gas-liquid mixer 202 to generate two-phase flows with different preset ratios, and the two-phase flows with preset ratios are injected into the measurement pipeline 10 through the second inlet.

[0091] S2. Collect the pressure differences on the upstream side and the downstream side of the orifice plate 11 by the differential pressure sensor 12, and collect the flow rate and density of the two-phase flow at each preset gas volume fraction by the data acquisition module 13.

[0092] S3. Based on the pressure difference data, flow rate data and density data collected each time, calculate the discharge coefficient of the two-phase flow at different preset gas volume fractions through discrete experiments;

[0093] The two-phase flow with a preset ratio flows through the measurement pipeline 10. The pressure difference between the upstream side and the downstream side of the orifice plate 11 can be measured by the differential pressure sensor 12, and parameters such as the flow rate and density of the preset two-phase flow can be measured by the Coriolis flowmeter. According to the formula:

[0094]

[0095] The discharge coefficient of the two-phase flow with a preset gas volume fraction can be measured. In the formula, q v is the flow rate of the two-phase flow, measured by the Coriolis flowmeter; β is the equivalent diameter ratio, which is the square root of the ratio of the orifice area of the orifice plate 11 to the cross-sectional area of the measurement pipeline 10; A is the cross-sectional area of the measurement pipeline 10; ρ is the density of the two-phase flow, measured by the Coriolis flowmeter; Δp is the pressure difference between the upstream side and the downstream side of the orifice plate 11, measured by the differential pressure sensor 12.

[0096] During measurement, at least three groups are measured at each gas volume fraction point and the average value is taken to reduce the measurement error. The gas volume fraction is measured from 0 to 1. C i The i in it represents the sampling times. When sampling for the first time, i takes the value of 1, when sampling for the second time, i takes the value of 2, and so on.

[0097] S4. Establish the correlation between the discharge coefficient and the gas volume fraction;

[0098] 1) Calculate the average value of the discharge coefficients at different preset gas volume fractions The calculation formula is:

[0099]

[0100] In the formula, N is the number of sampling points.

[0101] 2) Calculate the standard deviation sd of the discharge coefficient at different preset gas volume fractions C , and the calculation formula is:

[0102]

[0103] 3) Establish a correlation relationship In the formula, α is the gas volume fraction of the two-phase flow, where Vg is the gas volume, Vl is the liquid volume; λ1, λ2, γ1, γ2 are the coefficients of the relationship formula, which are determined by the least squares method;

[0104] Determine the correlation coefficients R1 and R2 in the correlation relationship by the least squares method.

[0105] S5. Introduce the two-phase flow to be measured into the first inlet of the measurement pipeline 10, collect the pressure difference between the upstream side and the downstream side of the orifice plate 11 through the pressure difference sensor 12, and collect the flow rate and density of the two-phase flow to be measured through the data acquisition module 13;

[0106] After the correlation relationship is established, close the second inlet, open the first inlet, introduce the two-phase flow to be measured into the measurement pipeline 10, the pressure difference between the upstream side and the downstream side of the orifice plate 11 can be measured through the pressure difference sensor 12, and parameters such as the flow rate and density of the two-phase flow to be measured can be measured through the Coriolis flowmeter.

[0107] S6. Based on the collected pressure difference data, flow rate data and density data of the two-phase flow to be measured, calculate the discharge coefficient of the two-phase flow to be measured, and apply the correlation relationship to estimate the gas volume fraction of the two-phase flow to be measured;

[0108] Calculate the discharge coefficient of the two-phase flow to be measured using the discharge coefficient formula, substitute the discharge coefficient of the two-phase flow to be measured into the correlation relationship, and the estimated value α1 can be calculated using the correlation relationship. The calculation formula is:

[0109]

[0110] The estimated value α2 can be calculated using the correlation relationship. The calculation formula is:

[0111]

[0112] Calculate the average value R of the correlation coefficient. The calculation formula is:

[0113]

[0114] Calculate the gas volume fraction α of the two-phase flow to be measured mea , and the calculation formula is:

[0115]

[0116] Through the above formula, the gas holdup α of the two-phase flow to be measured can be measured. mea .

[0117] The innovative point of the present invention lies in that during measurement, the first inlet is closed, and two-phase flows with different preset gas holdups are introduced into the measurement pipeline 10 through the second inlet. The pressure difference between the upstream side and the downstream side of the orifice plate 11 can be measured by the pressure difference sensor 12, and the actual flow rate and density of the two-phase flow can be measured by the data acquisition module 13. The discharge coefficient of the two-phase flow with different preset gas holdups can be calculated according to the discharge coefficient formula, and then the correlation relationship between the discharge coefficient and the gas holdup is established based on the different preset gas holdups and the calculated discharge coefficients. The relationship coefficients and correlation coefficients in the correlation relationship are calculated by using the least square method.

[0118] After obtaining the correlation relationship, the first inlet is opened and the second inlet is closed. The two-phase flow to be measured is introduced into the measurement pipeline 10 through the first inlet. The discharge coefficient of the two-phase flow to be measured can be calculated by using the pressure difference measured by the pressure difference sensor 12 and the actual flow rate and density of the two-phase flow measured by the data acquisition module 13. Then, the discharge coefficient is substituted into the correlation relationship to obtain the gas holdup of the two-phase flow to be measured. Compared with the related technology, the device is simpler, avoiding the use of equipment with harsh operating conditions or high costs such as capacitance analyzers, imaging holdup analyzers, and ray attenuation analyzers, has a wider application range, and is safe, environmentally friendly, and low-cost.

[0119] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments or perform equivalent replacements for some of the technical features. However, such modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A two-phase flow gas holdup measurement device, characterized in that Comprising: A measuring pipeline (10), including a first inlet and a second inlet, where the first inlet is for the two-phase flow to be measured to flow in, and the second inlet is for the two-phase flow with a preset gas-phase content to flow in; An orifice plate (11), arranged inside the measuring pipeline (10), with one side of the orifice plate (11) facing the first inlet and the second inlet, forming a flow-facing side, and the opposite side forming a flow-back side; A differential pressure sensor (12), arranged on the measuring pipeline (10) and suitable for measuring the differential pressure between the flow-facing side and the flow-back side; A data acquisition module (13), arranged on the measuring pipeline (10) and suitable for acquiring the flow rate and density of the two-phase flow inside the measuring pipeline (10).

2. The two-phase flow gas holdup measuring device according to claim 1, characterized in that, The data acquisition module (13) is arranged close to the flow-back side of the orifice plate (11).

3. The two-phase flow gas holdup measuring device according to claim 2, wherein The end of the measuring pipeline (10) is connected with a three-way valve (100), and the other two interfaces of the three-way valve (100) form the first inlet and the second inlet.

4. The two-phase flow gas holdup measuring device according to any one of claims 1-3, characterized in that, It further includes a two-phase flow module (20), and the two-phase flow module (20) is connected with the second inlet and is suitable for providing two-phase flows with different preset gas-phase contents.

5. The two-phase flow gas holdup measuring device according to claim 4, wherein, The two-phase flow module (20) includes a liquid storage tank (200), a gas storage tank (201), a gas-liquid mixer (202), a first pump (203), and a second pump (204); The liquid storage tank (200) is connected with the gas-liquid mixer (202) through the first pump (203) and is suitable for pumping a preset ratio of liquid into the gas-liquid mixer (202); The gas storage tank (201) is connected with the gas-liquid mixer (202) through the second pump (204) and is suitable for pumping a preset ratio of gas into the gas-liquid mixer (202); The gas-liquid mixer (202) is used for mixing the pumped liquid and gas to form a two-phase flow with a preset gas-phase content, and the outlet of the gas-liquid mixer (202) is connected with the second inlet.

6. The two-phase flow gas holdup measuring device according to claim 5, characterized in that, A first valve (205) is arranged between the liquid storage tank (200) and the gas-liquid mixer (202); and / or a second valve (206) is arranged between the gas storage tank (201) and the gas-liquid mixer (202).

7. A method for measuring the gas holdup of two-phase flow, characterized in that, Implemented by the two-phase flow gas-phase content measuring device according to any one of claims 1 - 6, including the following steps: Gradually introduce two-phase flows with different preset gas-phase contents into the second inlet of the measuring pipeline (10); Collect the differential pressures of each time between the flow-facing side and the flow-back side of the orifice plate (11) through the differential pressure sensor (12), and collect the flow rate and density of the two-phase flow at each preset gas-phase content through the data acquisition module (13); Based on the differential pressure data, flow rate data, and density data collected each time, calculate the discharge coefficient of the two-phase flow at different preset gas-phase contents through discrete experiments; Establish a correlation relationship between the discharge coefficient and the gas-phase content; Introduce the two-phase flow to be measured into the first inlet of the measuring pipeline (10), collect the differential pressure between the flow-facing side and the flow-back side of the orifice plate (11) through the differential pressure sensor (12), and collect the flow rate and density of the two-phase flow to be measured through the data acquisition module (13). Based on the differential pressure data, flow rate data, and density data of the two-phase flow to be measured collected, the discharge coefficient of the two-phase flow to be measured is calculated, and the gas volume fraction of the two-phase flow to be measured is estimated by applying the correlation formula.

8. The two-phase flow gas holdup measurement method according to claim 7, characterized in that The discharge coefficient C is calculated based on the following formula: where q v is the flow rate of the two-phase flow; β is the equivalent diameter ratio, which is the square root of the ratio of the orifice area of the orifice plate (11) to the cross-sectional area of the measuring pipe (10); A is the cross-sectional area of the measuring pipe (10); ρ is the density of the two-phase flow; and Δp is the pressure difference between the upstream side and the downstream side of the orifice plate (11).

9. The two-phase flow gas holdup measurement method according to claim 8, characterized in that The establishment of the correlation formula between the discharge coefficient and the gas volume fraction includes: Based on the differential pressure data, flow rate data, and density data collected each time, calculate the average value of the discharge coefficient at different preset gas volume fractions. Based on the average value of the discharge coefficient Calculate the standard deviation sd of the discharge coefficient at different preset gas volume fractions C ; Establish an association relationship In the formula, α is the gas volume fraction of the two-phase flow; λ1, λ2, γ1, γ2 are the relational coefficients, which are determined by the least squares method; The correlation coefficients R1 and R2 of the correlation formula are determined by the least squares method.

10. The two-phase flow gas volume fraction measurement method according to claim 9, characterized in that, The application of the correlation formula to estimate the gas volume fraction of the two-phase flow to be measured includes: Calculate the estimated value α1, Calculate the estimated value α2, Calculate the average value R of the correlation coefficient, Calculate the gas holdup α of the two-phase flow to be measured mea ,

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