CN113720403B - Moisture two-phase flow metering method and metering device - Google Patents
Moisture two-phase flow metering method and metering device Download PDFInfo
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- CN113720403B CN113720403B CN202110991518.6A CN202110991518A CN113720403B CN 113720403 B CN113720403 B CN 113720403B CN 202110991518 A CN202110991518 A CN 202110991518A CN 113720403 B CN113720403 B CN 113720403B
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- 238000000034 method Methods 0.000 title claims abstract description 41
- 230000005514 two-phase flow Effects 0.000 title claims abstract description 26
- 239000007788 liquid Substances 0.000 claims abstract description 138
- 238000005259 measurement Methods 0.000 claims abstract description 40
- 230000005499 meniscus Effects 0.000 claims description 23
- 238000010079 rubber tapping Methods 0.000 claims description 23
- 238000002360 preparation method Methods 0.000 claims description 8
- 230000005540 biological transmission Effects 0.000 claims 1
- 238000000926 separation method Methods 0.000 abstract description 22
- 238000009434 installation Methods 0.000 abstract description 5
- 239000007789 gas Substances 0.000 description 168
- 230000000694 effects Effects 0.000 description 11
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 8
- 239000003921 oil Substances 0.000 description 8
- 239000012071 phase Substances 0.000 description 8
- 230000006835 compression Effects 0.000 description 7
- 238000007906 compression Methods 0.000 description 7
- 239000007791 liquid phase Substances 0.000 description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
- 239000010779 crude oil Substances 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 239000012530 fluid Substances 0.000 description 3
- 238000011084 recovery Methods 0.000 description 3
- OTMSDBZUPAUEDD-UHFFFAOYSA-N Ethane Chemical compound CC OTMSDBZUPAUEDD-UHFFFAOYSA-N 0.000 description 2
- ATUOYWHBWRKTHZ-UHFFFAOYSA-N Propane Chemical compound CCC ATUOYWHBWRKTHZ-UHFFFAOYSA-N 0.000 description 2
- 239000000654 additive Substances 0.000 description 2
- 239000008346 aqueous phase Substances 0.000 description 2
- 230000005484 gravity Effects 0.000 description 2
- 239000003345 natural gas Substances 0.000 description 2
- 239000003129 oil well Substances 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000001273 butane Substances 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 239000008398 formation water Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- IJDNQMDRQITEOD-UHFFFAOYSA-N n-butane Chemical compound CCCC IJDNQMDRQITEOD-UHFFFAOYSA-N 0.000 description 1
- OFBQJSOFQDEBGM-UHFFFAOYSA-N n-pentane Natural products CCCCC OFBQJSOFQDEBGM-UHFFFAOYSA-N 0.000 description 1
- 239000001294 propane Substances 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
- G01F1/05—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using mechanical effects
- G01F1/34—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using mechanical effects by measuring pressure or differential pressure
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/24—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by centrifugal force
Abstract
The application relates to the technical field of flow metering, in particular to a wet gas two-phase flow metering method and a metering device, wherein the metering method comprises the following steps: acquiring a first measurement pressure difference of a first pressure taking point and a second pressure taking point, wherein the first pressure taking point and the second pressure taking point are positioned on the concave side of the arc section; acquiring the gas pressure and the gas temperature in the pipeline; obtaining gas density according to the gas pressure and the gas temperature; and obtaining the gas volume flow according to the first measurement pressure difference and the gas density. Moisture makes centrifugal motion in the arc section, gas moves on the concave side of the arc section, and liquid moves towards the convex side of the arc section under the action of centrifugal force, so that gas-liquid separation is realized. The first measuring pressure difference on the concave side of the arc section is obtained at the moment of gas-liquid separation, so that the influence of liquid on the first measuring pressure difference is effectively reduced, and the accuracy of the gas volume flow is improved; and occupy the volume less, be convenient for transportation and installation to be convenient for improve the suitability.
Description
Technical Field
The application relates to the technical field of flow metering, in particular to a wet gas two-phase flow metering method and a metering device.
Background
In the oil recovery industry, gas-liquid mixed fluids comprising liquid and gas phases are often produced from oil wells, often referred to in the industry as "wet gas", which is essentially a gas-liquid two-phase fluid having a low liquid content. Wherein the gas phase comprises an oilfield gas or any gas that does not condense at ambient temperature, such as methane, ethane, propane, butane, etc.; the liquid phase includes the oil phase as well as the aqueous phase, such as the crude oil itself, liquid additives dissolved in the crude oil during crude oil recovery, formation water, water injected into the well during oil recovery, and other liquid additives dissolved in the aqueous phase.
Moisture flow measurements are difficult relative to single phase fluids. Related moisture metering methods can be divided into two categories: one is to meter moisture using a conventional single-phase gas flow meter. Since moisture is a mixture of gas and liquid, the contained liquid can reduce the measurement accuracy of a single gas flow meter, resulting in inaccurate metering results. And secondly, sending the wet gas into a two-phase separator, separating the wet gas into gas and liquid phases by the separator, wherein an outlet of the gas-liquid separator is respectively provided with a gas flowmeter and a liquid flowmeter, and an outlet of the liquid phase is provided with a water meter to measure the oil and water ratio, so that the flow of the oil, the water and the gas is obtained. However, the system has large mass and volume, and the oil well is often in a remote area, so that the transportation and the installation are inconvenient, and the difficulty is increased for construction.
Therefore, these wet gas metering methods have many disadvantages, such as large gas flow errors and poor applicability.
Disclosure of Invention
In order to facilitate reducing the problems of large metering error and poor applicability, the application provides a moisture two-phase flow metering method and a metering device.
In a first aspect, the present application provides a method for measuring a moisture two-phase flow, which adopts the following technical scheme:
the wet gas two-phase flow metering method is realized based on a pipeline comprising at least one arc-shaped section, an input pipe and an output pipe, wherein the arc-shaped section is a pipeline with the same center, the input end of the arc-shaped section is connected with the input pipe, and the output end of the arc-shaped section is connected with the output pipe; the method comprises the following steps:
acquiring a first measurement pressure difference of a first pressure taking point and a second pressure taking point, wherein the first pressure taking point and the second pressure taking point are both positioned on the concave side of the same arc section;
acquiring the gas pressure and the gas temperature in the pipeline;
obtaining gas density according to the gas pressure and the gas temperature;
and obtaining the gas volume flow according to the first measurement pressure difference and the gas density.
Through adopting above-mentioned technical scheme, moisture is centrifugal motion in the arc section, and gaseous indent side at the arc section removes, and liquid removes to the evagination side of arc section under the effect of centrifugal force, realizes gas-liquid separation. The first measuring pressure difference on the concave side of the arc section is obtained at the moment of gas-liquid separation, so that the influence of liquid on the first measuring pressure difference is effectively reduced, and the accuracy of the gas volume flow is improved; the occupied volume is small, and the transportation and the installation are convenient, so that the applicability is convenient to improve;
the flow is calculated by adopting a differential pressure mode, so that the interference caused by using the liquid in the flow meter measuring cavity to the flow meter is effectively reduced, and the measurement accuracy is further improved.
Optionally, the first pressure tapping point is located at a most concave point of the concave side of the arc section, and the second pressure tapping point is located at the concave side of the outlet end of the arc section, wherein the most concave point is a midpoint of the concave side of the arc section.
Through adopting above-mentioned technical scheme, when moisture is centrifugal motion in the arc section, reach best gas-liquid separation effect at the most concave point of arc section indent side, after the gas-liquid separation, gas moves at the indent side of arc section, further reduces the liquid content in the gas to be convenient for improve the measurement accuracy of first measurement differential pressure.
Optionally, the pressure of the output pipe near the input pipe is collected as the gas pressure, and the temperature of the output pipe near the input pipe is collected as the gas temperature.
Through adopting above-mentioned technical scheme, moisture removes to the output tube through the arc section after the gas-liquid separation, and gas removes in the one side that the output tube is close to the input tube under the effect of centrifugal force, through obtaining inboard gas pressure and gas temperature, effectively reduces the possibility that gas-liquid mixes influence measurement accuracy.
Optionally, the method further comprises:
acquiring a second measurement pressure difference of a first pressure taking point and a third pressure taking point, wherein the third pressure taking point is positioned on the outer convex side in the arc section;
obtaining an actual differential pressure value brought by the liquid according to the first measured differential pressure and the second measured differential pressure;
and obtaining the moisture content according to the actual differential pressure value caused by the liquid.
Through adopting above-mentioned technical scheme, because liquid removes to the evagination side in the arc section under the effect of centrifugal force, obtain the second measurement pressure differential between indent side and the evagination side in the arc section and be related with the velocity of flow and the liquid content of gas to be convenient for judge the liquid content through the second measurement pressure differential, judge whether the gas-liquid separation effect is normal according to the liquid content, be convenient for revise measuring error.
Optionally, the third pressure tapping point is located at a most protruding point of the outer convex side in the arc-shaped section, and the most protruding point is a midpoint of the outer convex side of the arc-shaped section.
Through adopting above-mentioned technical scheme, when moisture is centrifugal motion in the arc section, reach best gas-liquid separation effect at the bump of arc section evagination side, and the liquid of bump is more, is convenient for improve the accuracy nature of second measurement differential pressure.
Optionally, the method for obtaining the liquid content includes:
according to the formulaObtaining the thickness of the liquid, wherein DeltaP 3 is the actual value of differential pressure caused by the liquid, r is the curvature radius, Q1 is the gas volume flow, D is the pipe diameter of the arc-shaped section, and ρ Liquid and its preparation method Is the density of the liquid;
taking the pipe diameter of the arc-shaped section as the diameter, taking the thickness of the liquid as the center distance, forming an equal-radius circle on the concave side and the convex side of the arc-shaped section, and obtaining the area of the equal-radius circle and the area of the overlapped part of the two equal-radius circles;
obtaining a meniscus area based on the area of the equal radius circle and the overlapping part area of the two equal radius circles, wherein the meniscus area is the sectional area of the liquid in the arc section;
and obtaining the liquid content based on the meniscus area and the area of the equal radius circle.
Optionally, the method further comprises:
obtaining the gas content of the moisture based on the liquid content;
and obtaining the corrected gas volume flow according to the gas content and the gas volume flow.
By adopting the technical scheme, because the moisture is gas-liquid mixed liquid, although the liquid content of the gas is lower after the moisture is subjected to gas-liquid separation, the error can be caused to the gas volume flow obtained by the first measurement pressure difference, and the gas volume flow needs to be corrected, so that the accuracy of measurement data is improved.
Optionally, the method further comprises:
acquiring the liquid speed;
and obtaining the volume flow of the liquid according to the meniscus area and the liquid speed.
Through adopting above-mentioned technical scheme, after carrying out gas-liquid separation to the moisture, still can exist liquid in the gas, can acquire liquid volume flow through meniscus area and liquid velocity to be convenient for realize the flow measurement of gas phase and liquid phase.
In a second aspect, the present application provides a moisture two-phase flow metering device, which adopts the following technical scheme:
a wet gas two-phase flow metering device comprising:
a conduit comprising at least one arcuate segment, an input conduit and an output conduit for transporting moisture; the arc-shaped section is a pipeline with the same circle center, the input end of the arc-shaped section is connected with the input pipe, and the output end of the arc-shaped section is connected with the output pipe;
the first pressure acquisition module comprises a first pressure acquisition unit arranged at a first pressure acquisition point and a second pressure acquisition unit arranged at a second pressure acquisition point, and is used for acquiring the pressure value of the first pressure acquisition point and the pressure value of the second pressure acquisition point and outputting a first measurement pressure difference; the first pressure taking point is positioned at the most concave point of the concave side of the arc-shaped section, and the second pressure taking point is positioned at the concave side of the outlet end of the arc-shaped section; wherein the most concave point is the midpoint of the concave side of the arc section;
the second pressure acquisition module is arranged in the pipeline and is used for measuring the gas pressure in the pipeline, and the temperature acquisition module is used for acquiring the gas temperature in the pipeline;
the control module is respectively connected with the first pressure acquisition module and the third pressure acquisition module and the temperature acquisition module, and is used for receiving the gas pressure and the gas temperature and outputting the gas density; the gas density and the first measured differential pressure are received and a gas volumetric flow rate is output.
Through adopting above-mentioned technical scheme, moisture is centrifugal motion in the arc section, and gaseous indent side at the arc section removes, and liquid removes to the evagination side of arc section under the effect of centrifugal force, realizes gas-liquid separation. The first measuring pressure difference on the concave side of the arc section is obtained at the moment of gas-liquid separation, so that the influence of liquid on the first measuring pressure difference is effectively reduced, and the accuracy of the gas volume flow is improved; and occupy the volume less, be convenient for transportation and installation to be convenient for improve the suitability.
Optionally, the method further comprises:
the third pressure acquisition module comprises a third pressure acquisition unit arranged at a third pressure acquisition point and is used for acquiring a pressure value of the third pressure acquisition point and outputting a second measurement pressure difference according to the pressure value of the first pressure acquisition point and the pressure value of the third pressure acquisition point; the third pressure tapping point is positioned at the most salient point of the outer convex side in the arc section; wherein the most salient point is the midpoint of the outer convex side of the arc-shaped section.
By adopting the technical scheme, as the liquid moves towards the outer convex side in the arc-shaped section under the action of centrifugal force, the second measurement pressure difference between the inner concave side and the outer convex side in the arc-shaped section is acquired to be related to the flow velocity and the liquid content of the gas, and the calculation of the liquid content based on the second measurement pressure difference is facilitated.
In summary, the present application includes at least one of the following beneficial technical effects:
moisture makes centrifugal motion in the arc section, gas moves on the concave side of the arc section, and liquid moves towards the convex side of the arc section under the action of centrifugal force, so that gas-liquid separation is realized. The first measuring pressure difference on the concave side of the arc section is obtained at the moment of gas-liquid separation, so that the influence of liquid on the first measuring pressure difference is effectively reduced, and the accuracy of the gas volume flow is improved; the occupied volume is small, and the transportation and the installation are convenient, so that the applicability is convenient to improve; the flow is calculated by adopting a differential pressure mode, so that the interference caused by using the liquid in the flow meter measuring cavity to the flow meter is effectively reduced, and the measurement accuracy is further improved.
Drawings
FIG. 1 is a schematic diagram of a wet gas two-phase flow metering device according to an embodiment of the present application.
FIG. 2 is a block diagram of a wet gas two-phase flow metering device according to one embodiment of the present application.
FIG. 3 is a flow chart of a method for moisture two-phase flow metering according to one embodiment of the present application.
FIG. 4 is a diagram of compression factors according to one embodiment of the present application.
Fig. 5 is a schematic view of two equal radius circles according to an embodiment of the present application.
Reference numerals illustrate: 1. a pipe; 11. an input tube; 12. an arc section; 13. an output pipe; 2. a second pressure acquisition module; 21. a gas pressure sensor; 3. a temperature acquisition module; 31. a temperature sensor; 4. a first pressure acquisition module; 41. a first differential pressure sensor; 5. a third pressure acquisition module; 51. a second differential pressure sensor; 6. a control module; 7. a first pressure tapping point; 8. a second pressure tapping point; 9. and a third pressure tapping point.
Detailed Description
The present application will be described in further detail with reference to the accompanying drawings.
In order to make the objects, technical solutions and advantages of the present application more apparent, embodiments of the present application will be described in further detail with reference to the accompanying drawings. It should be noted that the words "front", "rear", "left", "right", "upper" and "lower" used in the following description refer to directions in the drawings.
The embodiment of the application discloses a wet gas two-phase flow metering device.
As an embodiment of the wet gas two-phase flow metering device, as shown in fig. 1, the wet gas two-phase flow metering device comprises a pipeline 1 comprising at least one arc-shaped section 12, wherein the pipeline 1 can be provided as a U-shaped pipeline 1, an omega-shaped pipeline 1 with the arc-shaped section 12, and specifically, the pipeline 1 comprises an input pipe 11, at least one arc-shaped section 12 and an output pipe 13, wherein the input end of the arc-shaped section 12 is connected with the input pipe 11, and the output end of the arc-shaped section 12 is connected with the output pipe 13; and the arc section 12 is a pipeline with the same center, and can be set as a major arc or a minor arc.
In the oil exploitation process, after the oil gas well is completed, moisture flows out of the oil gas well through the pipeline 1, and when the moisture flows to the arc-shaped section 12, centrifugal motion is carried out in the arc-shaped section 12, gas moves on the concave side of the arc-shaped section 12, and liquid moves towards the outer convex side of the arc-shaped section 12 under the action of centrifugal force, so that gas-liquid separation is realized.
In addition, the pipeline 1 is in a horizontal state in the use process, so that the gravity influence of liquid in the flowing process is effectively reduced, and the gas-liquid separation effect of moisture in the arc-shaped section 12 is improved conveniently.
Referring to fig. 1 and 2, the metering device further comprises a first pressure acquisition module 4 mounted in the arcuate segment 12, a second pressure acquisition module 2 disposed in the output pipe 13, a temperature acquisition module 3 disposed in the output pipe 13, and a control module 6. The control module 6 is connected to the first pressure acquisition module 4, the second pressure acquisition module 2 and the temperature acquisition module 3, respectively.
Specifically, the first pressure acquisition module 4 includes a first pressure acquisition unit disposed at the first pressure acquisition point 7 and a second pressure acquisition unit disposed at the second pressure acquisition point 8, for acquiring a first measurement pressure difference between the first pressure acquisition point 7 and the second pressure acquisition point 8.
As one embodiment of the first pressure acquisition module 4, the first pressure acquisition module 4 includes a first differential pressure sensor 41 integrated with a first pressure acquisition unit and a second pressure acquisition unit, both of which are provided as pressure sensors, one end of the first differential pressure sensor 41 is connected to the first pressure taking point 7, and the other end is connected to the second pressure taking point 8; and the first differential pressure sensor 41 is connected to the control module 6. The first pressure taking point 7 is positioned at the most concave point of the concave side of the arc-shaped section 12, and the most concave point is the midpoint of the concave side of the arc-shaped section 12; the second tapping point 8 is located on the concave side of the outlet end of the arcuate segment 12.
The first differential pressure sensor 41 is configured to obtain a first measured differential pressure between the first pressure point 7 and the second pressure point 8, and send the first measured differential pressure to the control module 6.
As another embodiment of the first pressure acquisition module 4, the first pressure acquisition module 4 includes a controller, a first pressure acquisition unit disposed at the first pressure acquisition point 7, and a second pressure acquisition unit disposed at the second pressure acquisition point 8, specifically, the first pressure acquisition unit is set as a first pressure sensor, the second pressure acquisition unit is set as a second pressure sensor, the first pressure sensor and the second pressure sensor are respectively connected with the controller, and the controller is connected with the control module 6.
The first pressure sensor is used for measuring a first pressure at a first pressure taking point 7 and sending the first pressure to the controller; the second pressure sensor is used to measure a second pressure at a second tapping point 8 and to send the second pressure to the controller. The controller receives the first pressure and the second pressure, calculates a difference value between the first pressure and the second pressure to obtain a first measurement differential pressure, and sends the first measurement differential pressure to the control module 6.
Wherein the second pressure acquisition module 2 is arranged as a gas pressure sensor 21, the gas pressure sensor 21 being arranged on the side of the output pipe 13 close to the input pipe 11 for acquiring the gas pressure and sending the gas pressure to the control module 6. The temperature acquisition module 3 is configured as a temperature sensor 31, the temperature sensor 31 is disposed on one side of the output pipe 13 near the input pipe 11, and is used for acquiring the gas temperature and sending the gas temperature to the control module 6, and the control module 6 receives the gas pressure and the gas temperature and outputs the gas density.
The control module 6 outputs a gas volumetric flow rate based on the obtained first measured differential pressure and the gas density.
As another embodiment of the wet gas two-phase flow metering device, as shown in fig. 1 and 2, the wet gas two-phase flow metering device further includes a third pressure acquisition module 5, where the third pressure acquisition module 5 includes a third pressure acquisition unit installed at the third pressure tapping point 9, and is configured to acquire a pressure value of the third pressure tapping point 9, and output a second measurement differential pressure according to the pressure tapping value of the first pressure tapping point 7 and the pressure value of the third pressure tapping point 9.
As one embodiment of the third pressure acquisition module 5, the third pressure acquisition module 5 includes a second differential pressure sensor 51 integrated with the first pressure acquisition unit and the third pressure acquisition unit, and both of the first pressure acquisition unit and the third pressure acquisition unit are provided as pressure sensors. One end of the second differential pressure sensor 51 is connected with the first pressure taking point 7, the other end is connected with the third pressure taking point 9, and the second differential pressure sensor 51 is connected with the control module 6; the third pressure tapping point 9 is located at the most protruding point of the outer convex side in the arc-shaped section 12, the most protruding point is the midpoint of the outer convex side of the arc-shaped section 12, and the most concave point and the most protruding point of the same arc-shaped section 12 correspond.
The second differential pressure sensor 51 is configured to obtain a second measured differential pressure between the first pressure point 7 and the third pressure point 9, and send the second measured differential pressure to the control module 6.
As another embodiment of the third pressure acquisition module 5, the third pressure acquisition module 5 comprises a third pressure sensor arranged at a third pressure tapping point 9, which third pressure sensor is connected to the controller.
The third pressure sensor is arranged to measure a third pressure at a third tapping point 9 and to send the third pressure to the controller. The controller receives the first pressure and the third pressure, calculates a difference between the first pressure and the second pressure to obtain a second measured differential pressure, and sends the second measured differential pressure to the control module 6.
Based on the wet gas two-phase flow metering device, the embodiment of the application also discloses a wet gas two-phase flow metering method.
As an embodiment of the moisture two-phase flow metering method, in conjunction with fig. 3, the following steps are included:
s1, acquiring a first measurement pressure difference of a first pressure taking point 7 and a second pressure taking point 8, wherein the first pressure taking point 7 and the second pressure taking point 8 are both positioned on the concave side of the same arc section 12;
as one embodiment of the first measured differential pressure obtaining method, the control module 6 receives the first measured differential pressure between the first pressure taking point 7 and the second pressure taking point 8 sent by the first differential pressure sensor 41.
Wherein, the moisture flows through the pipeline 1 of at least one arc section 12, and the centrifugal motion is carried out at the arc section 12, and gas moves at the concave side of the arc section 12, and liquid moves towards the convex side of the arc section 12 under the action of centrifugal force, thereby realizing gas-liquid separation. The first measurement pressure difference on the concave side of the arc-shaped section 12 is obtained at the moment of gas-liquid separation, so that the liquid content in the gas is effectively reduced, and the first measurement pressure difference is convenient to accurately obtain.
S2, acquiring the gas pressure and the gas temperature in the pipeline 1;
the control module 6 receives the gas pressure sent by the gas pressure sensor 21 and the gas temperature sent by the temperature sensor 31.
Specifically, moisture moves to the output pipe 13 through the arc section 12 after gas-liquid separation, gas moves at the concave side of the arc section 12 under the action of centrifugal force and moves at one side of the output pipe 13 close to the input pipe 11, and the possibility that the measurement accuracy is affected by gas-liquid mixing is effectively reduced by acquiring the gas pressure and the gas temperature at the inner side.
The steps S1 and S2 are not required to be performed sequentially, and may be performed simultaneously or sequentially in any order.
S3, obtaining gas density according to the gas pressure and the gas temperature;
from the gas pressure in the pipe and the gas temperature, it is known that the gas density is proportional to the gas pressure and inversely proportional to the temperature in combination with PVT equation pv=nrt. From this, it follows that pressure and temperature are critical quantities for obtaining gas density.
As one embodiment of the gas density acquisition method, the formula is usedObtaining a gas volume, wherein n is a gas mole coefficient, T is a gas temperature, and P is a gas pressure; r= 8.314 j.mol -1 ·K -1 Referred to as the molar gas constant.
According to the formulaThe molar volume of the gas is obtained and is expressed according to the formula +.>The gas density, m, is the gas molar mass, is obtained. Since the main component in the moisture is natural gas, and the gas molar mass of the natural gas is 16g/mol.
As another embodiment of the gas density acquisition method, the ideal gas state equation is no longer applicable when the pressure is high. Under the working condition that the ideal gas state equation is deviated, the compression factor Z is required to be introduced for correction.
Wherein, the definition formula of compression factor is:wherein V is m, true For true gas molar volume, V m, ideal Is the ideal gas mole volume. The compression factor Z is a correction factor that must be considered when the ideal gas state equation is applied to the actual gas, and is the ratio of the actual gas molar volume to the ideal gas molar volume under the same conditions, and its magnitude reflects the degree to which the actual gas deviates from the ideal gas. The Z value of the ideal gas is always 1 under any condition; z is less than 1, which indicates that the true gas molar volume is less than the ideal gas molar volume under the same conditions, and the true gas is easier to compress than the ideal gas; z greater than 1 indicates that the true gas molar volume is greater than the ideal gas molar volume under the same conditions, and that the true gas is harder to compress than the ideal gas.
The gas pressure P in the pipe is obtained by the gas pressure sensor 21, and the gas temperature T in the pipe is obtained by the temperature sensor 31. According to the formulaObtaining a comparison temperature T r Wherein T is c Is the critical temperature, i.e. the highest temperature allowed for the gas to liquefy; according to the formula->Obtaining the comparative temperature P r Wherein P is c Is critical pressure, i.e. at T c The minimum pressure required to liquefy the gas is set. Taking methane as an example, T c ＝-82.62℃，P c ＝4.596MPa。
Referring to FIG. 4, according to T r P r Acquiring and T in compression factor graph r P r A corresponding compression factor Z.
For example: t of ethane c ＝32.18℃，P c =4.872 MPa, t=80 ℃, p=6.24 MPa, then Making an auxiliary line on the compression factor graph to estimate T r ＝1.157，P r The corresponding Z value when=1.28, where z=0.64.
According to the formulaObtaining the true gas molar volume, finally according to the formula +.>The gas density is obtained, so that the gas density of the real gas is conveniently obtained, and the accuracy of the gas density is conveniently improved.
And S4, obtaining the gas volume flow according to the first measurement pressure difference and the gas density.
As an embodiment of the gas volume flow, the formula is followed Calculating a gas volume flow Q, wherein DeltaP 1 is the absolute value of the first measured differential pressure ρ Air flow For gas density, k1 is the measurement coefficient, and k1 is related to the shape of the pipe and the pipe inner diameter.
In order to improve the measurement accuracy of the first measured differential pressure, as shown in fig. 1, further, the first pressure tapping point 7 is located at the most concave point on the concave side of the arc-shaped section 12, and the second pressure tapping point 8 is located at the outlet end of the concave side of the arc-shaped section 12, wherein the most concave point is the midpoint of the concave side of the arc-shaped section 12.
It should be noted that, when the moisture is in centrifugal motion in the arc-shaped section 12, the most concave point on the concave side of the arc-shaped section 12 achieves the best gas-liquid separation effect, and after gas-liquid separation, the gas moves faster and moves on the concave side of the arc-shaped section 12, so that the liquid content in the gas is further reduced, and the measurement accuracy of the volume flow of the gas is improved conveniently.
Since the wet gas is a gas-liquid mixed liquid, although the liquid still exists in the pipe 1 after the wet gas is separated from the gas, an error is caused to the gas volume flow obtained by the first measured differential pressure, and a correction process is required to be performed to the gas volume flow.
As one embodiment of the correction process, the method includes the steps of:
s41, acquiring a second measurement pressure difference of the first pressure taking point 7 and the third pressure taking point 9, wherein the third pressure taking point 9 is positioned on the outer convex side in the arc-shaped section 12.
Specifically, the pressure difference between the concave side and the convex side of the arc segment 12 is obtained by the second differential pressure sensor 51 provided at the first pressure pickup point 7 and the third pressure pickup point 9.
S42, obtaining an actual differential pressure value caused by the liquid according to the first measured differential pressure and the second measured differential pressure.
Specifically, in the pure gas state, the first measured pressure difference Δp1 measured between the first and second pressure take-off points 7, 8 is a function of the gas volume flow Q1, i.eThe second measured pressure difference Δp2 measured between the first tapping point 7 and the third tapping point 9 is also functionally similar to the gas volume flow Q1, i.e.Where k2 is the measurement coefficient and k2 is related to the shape of the pipe and the pipe inner diameter. From this, it can be seen +.>Then->
In the wet state, the second differential pressure measured at the first pressure-taking point 7 and the third pressure-taking point 9 is denoted as Δp3', the actual differential pressure caused by the gas is Δp2, and Δp3' =Δp3+Δp2 is obtained according to the formula Δp3' =Δp3+Δp2, where Δp3 is the actual differential pressure caused by the liquid
S43, obtaining the moisture content according to the actual differential pressure value caused by the liquid.
Specifically, the liquid moves to the outer convex side of the arcuate segment 12 under the action of centrifugal force, and the gas moves to the inner concave side of the arcuate segment 12. The first measured differential pressure is the differential pressure on the concave side of the arcuate segment 12, and is related to the flow rate of the gas; the second measured differential pressure is the differential pressure between the concave side and the convex side of the arcuate segment 12, and is related to the flow rate of the gas and the liquid content, i.e., in the case of a certain flow rate of the gas, the second measured differential pressure is positively related to the liquid content.
It should be noted that, during the process of conveying the wet gas in the pipe 1, a certain flow rate is provided, and if the flow rate is less than the preset threshold value, the flow rate is insufficient to cause the liquid to be distributed on the outer convex side of the arc-shaped section 12 due to centrifugal action; if the flow rate is greater than the preset threshold value, the liquid forms meniscus geometric distribution in the arc-shaped section 12 and is attached to the outer convex side of the arc-shaped section 12; wherein the liquid level is curved where the liquid contacts the arcuate segment 12, the curved portion of which is referred to as the meniscus.
Neglecting the effects of gravity, the maximum thickness of the meniscus is at the midpoint of the outer convex side of the arc segment 12, i.e. at the third tap point 9. In the case of a meniscus formed where the liquid contacts the arcuate segment 12, the maximum thickness of the meniscus is measured and the area of the meniscus is calculated, whereby the ratio of the cross-sectional liquid area, i.e. the liquid content, is derived based on the area of the meniscus.
The method for obtaining the liquid content in S43 includes:
s431, according to the formulaObtaining the thickness of the liquid, wherein DeltaP 3 is the actual value of differential pressure caused by the liquid, r is the curvature radius, Q1 is the gas volume flow, D is the pipe diameter of the arc-shaped section (12), ρ Liquid and its preparation method Is the density of the liquid;
as an embodiment of the method for obtaining the maximum thickness of the meniscus, since DeltaP 3 is obtained by the centrifugal force caused by the centrifugal motion of the liquid, thenWherein m is 1 Is the liquid mass, r is the radius of curvature, v Liquid and its preparation method The liquid speed is the liquid speed, s is the pressure taking area; the radius of curvature r is a geometric constraint of the arcuate segment 12 such that the radius of curvature r is known. And m is 1 ＝V1×ρ Liquid and its preparation method V1 is the volume of the liquid at the third pressure taking position, ρ Liquid and its preparation method Is the liquid density.
From the following componentsObtaining gas velocity +.> In case of neglecting the gas-liquid flow rate difference, the liquid velocity +.> Then Where D is the tube diameter of the arcuate segment 12 and H is the liquid thickness, i.e., the maximum thickness of the meniscus.
S432, forming equal-radius circles on the concave side and the convex side of the arc-shaped section 12 by taking the thickness of the liquid as the center distance, and obtaining the area of the equal-radius circles and the area of the overlapped part of the two equal-radius circles.
Regarding the pipe diameter of the arc-shaped section 12 as the diameter, regarding the concave side and the convex side of the arc-shaped section 12 as two staggered equal-radius circles, wherein H is the center distance of the circles, and deducing the overlapping part area of the two staggered equal-radius circles by a geometric formula, namely Wherein R is the radius of a circle with equal radius,
s433, obtaining the meniscus area based on the area of the equal radius circle and the overlapping part area of the two equal radius circles, wherein the meniscus area is the sectional area of the liquid in the arc-shaped section 12.
Specifically, the meniscus area S m ＝S1-S d ＝πR 2 -S d Where S1 is the area of an equal radius circle.
And S434, obtaining the liquid content based on the meniscus area and the area of the equal-radius circle.
Specifically, according to the formulaObtaining the liquid content delta Liquid and its preparation method 。
S44, obtaining the air content of the moisture based on the liquid content.
By the formula delta Air flow ＝1-δ Liquid and its preparation method Obtaining the air content delta Air flow 。
S45, obtaining the corrected gas volume flow according to the gas content and the gas volume flow.
Specifically, the gas volume flow obtained from the first measured differential pressure is multiplied by the moisture content to obtain a corrected gas volume flow Q2, i.e
As another embodiment of the wet gas two-phase flow metering method, the liquid volume flow Q3 can be obtained based on the meniscus area and the liquid velocity under the condition of neglecting the gas-liquid flow velocity difference, namelyWherein S is d Is the overlapping area of two equal radius circles, and D is the pipe diameter of the arc-shaped section 12. The gas volume flow and the liquid flow are conveniently detected simultaneously, so that the applicability is conveniently improved.
The above embodiments are not intended to limit the scope of the present application, so: all equivalent changes in structure, shape and principle of the application should be covered in the scope of protection of the application.
Claims (8)
1. The method is characterized by being realized based on a pipeline (1) comprising at least one arc-shaped section (12), an input pipe (11) and an output pipe (13), wherein the arc-shaped section (12) is a pipeline with the same center, the input end of the arc-shaped section (12) is connected with the input pipe (11), and the output end of the arc-shaped section (12) is connected with the output pipe (13); the method comprises the following steps:
acquiring a first measurement pressure difference of a first pressure taking point (7) and a second pressure taking point (8), wherein the first pressure taking point (7) and the second pressure taking point (8) are both positioned on the concave side of the same arc section (12);
acquiring the gas pressure and the gas temperature in the pipeline (1);
obtaining gas density according to the gas pressure and the gas temperature;
obtaining a gas volume flow according to the first measurement pressure difference and the gas density;
acquiring a second measured pressure difference of the first pressure taking point (7) and a third pressure taking point (9), wherein the third pressure taking point (9) is positioned on the outer convex side in the arc-shaped section (12);
obtaining an actual differential pressure value brought by the liquid according to the first measured differential pressure and the second measured differential pressure;
and obtaining the moisture content according to the actual differential pressure value caused by the liquid.
2. A method of moisture two-phase flow metering as set forth in claim 1 wherein: the first pressure taking point (7) is positioned at the most concave point of the concave side of the arc-shaped section (12), and the second pressure taking point (8) is positioned at the concave side of the outlet end of the arc-shaped section (12); wherein the most concave point is the midpoint of the concave side of the arc-shaped section (12).
3. A method of moisture two-phase flow metering as set forth in claim 1 wherein:
and collecting the pressure of the output pipe (13) at the side close to the input pipe (11) as the gas pressure, and collecting the temperature of the output pipe (13) at the side close to the input pipe (11) as the gas temperature.
4. A method of moisture two-phase flow metering according to claim 1, characterized in that the third tapping point (9) is located at the most convex point of the outer convex side in the arcuate segment (12), the most convex point being the midpoint of the outer convex side of the arcuate segment (12).
5. The method for measuring the flow rate of two phases of moisture according to claim 1, wherein the method for obtaining the liquid content comprises the steps of:
according to the formulaObtaining the thickness of the liquid, wherein DeltaP 3 is the actual value of differential pressure caused by the liquid, r is the curvature radius, Q1 is the gas volume flow, D is the pipe diameter of the arc-shaped section (12), ρ Liquid and its preparation method Is the density of the liquid;
taking the pipe diameter of the arc-shaped section (12) as the diameter, taking the thickness of the liquid as the center distance, forming equal-radius circles on the concave side and the convex side of the arc-shaped section (12), and obtaining the area of the equal-radius circles and the area of the overlapped part of the two equal-radius circles;
obtaining a meniscus area based on the area of the equal radius circle and the overlapping part area of the two equal radius circles, wherein the meniscus area is the sectional area of the liquid in the arc-shaped section (12);
and obtaining the liquid content based on the meniscus area and the area of the equal radius circle.
6. The method of claim 5, further comprising:
obtaining the gas content of the moisture based on the liquid content;
and obtaining the corrected gas volume flow according to the gas content and the gas volume flow.
7. The method of claim 5, further comprising:
acquiring the liquid speed;
and obtaining the volume flow of the liquid according to the meniscus area and the liquid speed.
8. A wet gas two-phase flow metering device, comprising:
a pipe (1) comprising at least one arcuate section (12), an inlet pipe (11) and an outlet pipe (13) for the transmission of moisture; the arc-shaped section (12) is a pipeline with the same circle center, the input end of the arc-shaped section (12) is connected with the input pipe (11), and the output end of the arc-shaped section (12) is connected with the output pipe (13);
the first pressure acquisition module comprises a first pressure acquisition unit arranged at a first pressure acquisition point (7) and a second pressure acquisition unit arranged at a second pressure acquisition point (8), and is used for acquiring the pressure value of the first pressure acquisition point (7) and the pressure value of the second pressure acquisition point (8) and outputting a first measurement pressure difference; the first pressure taking point (7) is positioned at the most concave point of the concave side of the arc-shaped section (12), and the second pressure taking point (8) is positioned at the concave side of the outlet end of the arc-shaped section (12); wherein the most concave point is the midpoint of the concave side of the arc-shaped section (12);
a second pressure acquisition module (2) and a temperature acquisition module (3) which are installed in the pipeline (1), wherein the second pressure acquisition module (2) is used for measuring the gas pressure in the pipeline (1), and the temperature acquisition module (3) is used for acquiring the gas temperature in the pipeline (1);
the control module (6) is respectively connected with the first pressure acquisition module and the second pressure acquisition module (2) and the temperature acquisition module (3) and is used for receiving the gas pressure and the gas temperature and outputting the gas density; receiving the gas density and a first measured differential pressure and outputting a gas volumetric flow;
the wet gas two-phase flow metering device further comprises a third pressure acquisition module (5), wherein the third pressure acquisition module (5) comprises a third pressure acquisition unit arranged at a third pressure acquisition point (9) and is used for acquiring a pressure value of the third pressure acquisition point (9) and outputting a second measurement pressure difference according to the pressure value of the first pressure acquisition point (7) and the pressure value of the third pressure acquisition point (9); the third pressure tapping point (9) is positioned at the most salient point of the outer convex side in the arc section (12); wherein the most salient point is the midpoint of the outer convex side of the arc-shaped section (12);
the control module (6) is further used for obtaining an actual differential pressure value caused by the liquid according to the first measured differential pressure and the second measured differential pressure; and obtaining the moisture content according to the actual differential pressure value caused by the liquid.
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