CN102116754A - Multiphase flow measurement method based on double-section impedance type long waist cone sensor - Google Patents

Abstract

The invention belongs to the fluid measurement technology field and relates to a multiphase flow measurement method based on a double-section impedance type long waist cone sensor. The adopted sensor comprises a cone throttling element, a systolic blood pressure drop differential pressure transmitter, a permanent pressure loss differential pressure transmitter and an electrical sensitive sensor. The method comprises the following steps: collecting two pairs of differential pressure signals generated by the cone throttling element; utilizing the electrical sensitive sensor to collect an electrical signal; calculating the total mass flow rate, the each-phase mass flow rate and the each-phase mass content according to a double-differential pressure model of a single throttling element; utilizing a support vector machine to realize classify, identify and pre-judge a flow pattern according to the measurement data of the differential pressure signals and the electrical signal; adopting a capacitance model to measure a mixed fluid dielectric constant; adopting a conductivity model to measure the mixed fluid conductivity; and calculating the procedure parameter of oil-gas-water three-phase flow. The multiphase flow measurement method is not influenced by the fact that whether a multiphase flow continuous phase is conducted or not, has the characteristics of high measurement precision, high reliability and the like and can obtain more measurement information.

Description

Multiphase flow measurement method based on the long waist inner cone of double sections impedance type sensor

Technical field

The invention belongs to the fluid measurement technical field, be specifically related to a kind of measuring method that merges differential pressure measurement principle and electrical measurement principle, be used for determining that each phase component of polyphasic flow in external phase is from conductive phase to non-conductive phase scope contains parameters such as rate, flow velocity and flow.The present invention is measured as description object with oil/gas/water multiphase, but is not limited in this application, and measuring method of the present invention still is suitable in other industrial processs and chemical reaction.

Technical background

Polyphasic flow is often referred to and has flowing of two or more material simultaneously, comprises biphase gas and liquid flow, Dual-Phrase Distribution of Gas olid, liquid fixed double phase flow, liquid-liquid diphasic flow and gas-liquid liquid and gas-liquid-solid multiphase flow etc.Polyphasic flow often appears in modern project field such as power, nuclear energy, chemical industry, oil, refrigeration, metallurgy, pipeline transportation, aerospace, medicine, food and the equipment, as not realizing just can't guaranteeing the accurate measurement of its flow process parameter the reliable design and the safe operation of relevant devices in the pipeline.The popularity that polyphasic flow exists in nature and industrial process and the importance of application make it occupy crucial status in national economy and daily life.Along with power industry and petrochemical industry develop rapidly, and, impel the work of polyphasic flow area research to develop rapidly, become at present and give the front subject greatly paid close attention to both at home and abroad the pay attention to day by day of environmental protection.

Because each alternate interfacial effect and relative velocity of existing of polyphasic flow, phase interface all is random variation on time and space, and the flow characteristics that causes polyphasic flow is more than the single-phase flow complexity, and characteristic parameter is also many than single-phase flow.The oil gas water three phase flow measuring method can be divided into two aspects at present: 1, polyphasic flow is regarded as the measurement that biphase gas and liquid flow carries out flow.2, each phase component in the polyphasic flow is contained the measurement of rate.The method of wherein polyphasic flow being regarded as gas-liquid two-phase flow measurement flow mainly contains: correlation method, volumetric method, flow limit method, turbine type detection method, laser Doppler method, PIV particle imaging velocimetry, hot line hot film anemometer, process tomographic imaging technology, nuclear magnetic resonance method and Coriolis method etc., this several method has wide range of applications, but needs other subsidiary means (as densitometer etc.) to measure void fraction.The measuring method of phase content has two kinds, and the one, indirect method promptly returns by experiment or theoretical derivation draws the phase content calculating formula that physical parameter and technological parameter with the gas-liquid two-phase medium are function; The 2nd, the measurement mechanism direct method of measurement is as Electromagnetic Wave Detection method, conductance method, capacitance method, calorifics method, microwave method, γ component table method and nuclear magnetic resonance method etc.In actual measurement, generally adopt the measurement mechanism direct method of measurement to determine phase content.

Using that traditional single-phase flow measurement instrument combines with two-phase flow auxiliary parameter measurement means is a kind of main thought that solves polyphasic flow procedure parameter problems of measurement in the pipeline.Differential pressure flowmeter as orifice plate, Venturi tube, nozzle and inner cone flow meter etc., is to use maximum online flow measurement instruments of a kind of industry at present, and is also commonplace in the research of polyphasic flow procedure parameter fields of measurement.Wherein inner cone flow meter notion that the fluid throttling is retracted to pipeline center's near axis fundamentally change into utilize the coaxial cone that is installed in pipeline center with fluid gradually throttling be retracted to inner-walls of duct, determine fluid flow by differential pressure before and after measuring cone.Interior cone flow meter can be under shorter straight length condition, with wideer range ratio clean or dirty fluid is realized more accurate, more effective flow measurement, but also there are some shortcomings in himself design feature: there is pulsation in the pressure signal to exist the whirlpool district to cause herein at the cone afterbody, measuring accuracy and repeatability are reduced, and whole crushing is bigger, as flow performance inner cone flow meter is done malformation according to polyphasic flow, as inner venturi tube, spindle flowmeter and Shuttle Type Flow Meter etc., can effectively improve its precision and stability in multiphase flow measurement.Based on the multiphase flow measurement method of the responsive principle of electricity existing theory and application foundation preferably, electrical parameter (electrical impedance, specific inductive capacity etc.) by the measuring channel inner fluid changes the measurement that each phase component of realization polyphasic flow contains rate, and this method is divided into mode such as condenser type, conductance type according to the difference of measurement parameter.If adopt multi-modal sensor and multi-operation mode (excitation measurement strategies) combined method, utilize the measurement advantage of each mode, can realize the comprehensive extraction of polyphasic flow procedure parameter by Combinatorial Optimization, and the acquisition all-sidedly and accurately of flowing information.

Patent CN99257650.4, CN200420093532.6, CN200420061026.9 have announced a kind of special-shaped Venturi tube, spindle flowmeter, Shuttle Type Flow Meter that is used for restriction device respectively, be overcome in the cone flow meter some shortcomings design.The interior relatively cone flow meter of special-shaped Venturi tube is at waist, increase the equal diameter section, form annular free air space, help to improve the stability of efflux coefficient, but it is short and angle is big that kinetic energy is converted into the conical diffuser of outlet of potential energy, fluid produces whirlpool by separating after the cone, and the interior relatively cone flow meter of permanent crushing there is no obvious improvement.Spindle flowmeter and Shuttle Type Flow Meter are very approaching, only difference to some extent on appearance profile: the throttling element of spindle flowmeter is fairshaped spindle, and the fusiformis body that the throttling element of Shuttle Type Flow Meter is made up of precentrum, middle equal diameter segment body and posterior pyramids, throttling element is installed along conduit axis, the centre has one section sufficiently long equal diameter section, and forms uniform circular passage between the inner-walls of duct.These two kinds of deformable bodys are in efflux coefficient stability, anti-interference fluidity and low pressure loss all are better than interior cone flow meter, but throttling element long (4 times to internal diameter of the pipeline), the comparison heaviness seems when caliber is big, and it is single relatively to measure the polyphasic flow procedure parameter, needs to cooperate the measurement of other flowmeters ability complete process parameters.

Patent CN86207384, CN200810151346.6, CN03234526.7 have announced " mixer+double-venturi tube " moisture measuring device that Venturi tube restriction device and throttle orifice plate apparatus combination, inner cone restriction device and the combination of Venturi tube restriction device, the combination of two inner cone restriction device and Britain Solartron company propose respectively, adopt two differential pressure methods to measure gas-liquid two-phase and contain rate and flow, be i.e. two kinds of similar or inhomogeneous restriction device multiple measurement biphase gas and liquid flow procedure parameters.Utilize the homogeneous flow model, the differential pressure signal that obtains on the restriction device to the different flow coefficient is handled, obtain the gas phase quality and contain rate, obtain gas-liquid separate phase flow rate in the fluid-mixing by the total mass flow calculation of fluid-mixing then, simultaneously the gas-liquid flow is carried out the temperature and pressure compensation.This combined method only is applicable to measure mixes two-phase fluid uniformly, and two restriction devices fit together the consistance that can not guarantee on the space, therefore two-phase flow flow pattern and procedure parameter in flow process is difficult to be consistent, run counter to easily that combined type measures precondition---promptly there is original reason error in the constant principle of its basic parameter when two-phase fluid flows through each ingredient.

Patent US 5485743, US 5130661, US 6857323, US 6940286, CN99209502.6, CN200680055193.4 etc. have announced employing process tomographic imaging technology measurement polyphasic flow procedure parameter.Process tomographic imaging is made up of the sensor space array, data acquisition and the processing unit that obtain the measured object field information, image reconstruction and thing field parameter extraction unit, the sensor array is set up responsive successively in measurement space under certain mode of operation, by data acquisition and processing unit the signal that reflects detected material field dielectric distribution in the different sensitizing ranges is gathered and handled, use image algorithm to reconstruct the image of reflection dielectric distribution then, adopt certain information processing method to extract required parameter on this basis.Yet chromatography imaging technique does not satisfy industrial application requirements as yet at aspects such as real-time, measuring accuracy and picture qualities, and the quick variation characteristic of polyphasic flow conflicts with the complicacy of tomography image reconstruction algorithm, may cause result of calculation to exist than mistake.

Summary of the invention

The objective of the invention is deficiency, provide a kind of and can measure the polyphasic flow procedure parameter, and realize that according to each sensor own characteristic the signal between sensor is complementary and redundant, realize measuring optimized multiphase flow measurement method at above-mentioned prior art existence.Measuring method of the present invention, a kind of long waist inner cone restriction device and a kind of double sections electricity sensitive sensor is combined, do not carry out pre-separation or mixing to measuring fluid, realize the polyphasic flow procedure parameter in external phase is from conductive phase to non-conductive phase scope, accurate measurement as a minute phase content (cross section phase content, quality phase content), phase-splitting flow velocity, volumetric flow rate and mass rate, carry out flow pattern identification by the analysis to measure signal, to optimize measurement result.Technical scheme of the present invention is as follows:

A kind of multiphase flow measurement method based on the long waist inner cone of double sections impedance type sensor, the sensor that adopts comprises segment of cone stream part, contraction pressure drop differential pressure transmitter, permanent crushing differential pressure transmitter, the electricity sensitive sensor, described cone throttling element is a kind of long waist inner cone restriction device, by the leading portion cone, constitute for three sections as stage casing column, the back segment cone of cone waist, by the coaxial pipeline center of being fixed in of support, form annular free air space with the tube wall of pipeline; Two pressure ports of described contraction pressure drop differential pressure transmitter, one is arranged on cone throttling element upstream end, and another is arranged on annular free air space place or cone afterbody; Two pressure ports of described permanent crushing differential pressure transmitter are separately positioned on recovery place of cone throttling element upstream and downstream pressure; Described electricity sensitive sensor comprises first group and the second group electrode on the different cross section that is distributed in annular free air space place, and first group of electrode is used to detect the fluid-mixing conductivity, and second group is used to detect the fluid-mixing specific inductive capacity; Every group of electrode is made of electrode in one or more and one or more external electrode, and interior electrode is fixed on cone waist surface, and external electrode is fixed on inner-walls of duct; During measurement, as excitation/potential electrode and ground-electrode, this measuring method comprises the following steps: respectively for each interior electrode of gating and its corresponding external electrode

1) gathers two pairs of differential pressure signals that produce by the cone throttling element: shrink pressure drop differential pressure signal Δ p and permanent crushing differential pressure signal δ p;

2) utilize the electricity sensitive sensor to gather electric signal;

3), obtain total mass flow rate, each phase mass rate, each phase quality and contain the relational expression between rate and the phase content according to two differential pressure models of following single throttling element:

A. according to formula

With

Calculate equivalent mass flow W _Mtp1, W _Mtp2, in the formula, ε is an expansibility factor, C ₁For shrinking pressure drop Δ p is the efflux coefficient that differential pressure signal calibrates, C ₂For permanent crushing δ p is the efflux coefficient that differential pressure signal calibrates, A ₀Be the circulation area of annular free air space, A is the pipeline circulation area, and β is the equivalent diameter ratio of flow area, ρ _gBe density of gas phase;

B. with formula

Compare, calculate L-M parameter χ, in the formula,

Be two-phase flow multiplier, W _MgBe gas phase mass flow, a ₁, b ₁, a ₂, b ₂Be the rating test parameter;

C. according to formula Obtain that the gas phase quality contains rate x, the liquid phase quality contains rate 1-x and cross section oil content α _o, cross section water percentage α _w, void fraction α _gBetween relational expression, in the formula,

Be two-phase flow multiplier, ρ _gBe density of gas phase, ρ ₁Be density of liquid phase,

α _oBe cross section oil content, α _wBe cross section water percentage, α _gBe void fraction, ρ _oBe oil phase density, ρ _wBe water density;

D. according to formula

Calculate gas phase mass flow W _g, liquid phase mass rate W _l, total mass flow rate W _mWith cross section oil content α _o, cross section water percentage α _w, void fraction α _gBetween relational expression;

4) according to differential pressure signal and electric signal measurement data, carry out classification, the identification and judgement of flow pattern, judge that external phase is conductive phase or non-conductive phase in the fluid;

Whether be conductive phase according to external phase 5), adopt different computation models to calculate the procedure parameter of oil-gas-water three-phase flow, if external phase is conductive phase, the computation model of employing is as follows:

A. according to the voltage signal of first group of electrode collection, calculate the conductivity of fluid-mixing _m

B. known water conductivity _w, according to formula α _l+ α _g=1 He

Calculate cross section oil content α _o, cross section water percentage α _wWith void fraction α _g, in the formula, σ _mBe profit gas mixed conductivity;

C. previous step is obtained to such an extent that each phase cross section c step and d of containing rate substitution step 3) goes on foot determined two relational expressions, in calculate total mass flow rate, each phase mass rate and each phase quality and contain rate;

D. according to formula

Calculate the total volumetric flow rate Q of fluid-mixing _v, in the formula, ρ _mBe the fluid hybrid density;

E. according to formula

Calculate the oil phase volume flow Q _Vo, the water volume flow Q _VwWith gas phase volume flow rate Q _Vg

F. according to formula

Calculate oil phase flow velocity V _o, aqueous phase flow rate V _wWith gas phase flow velocity V _gIf external phase is non-conductive phase, the computation model of employing is as follows:

A. according to the voltage signal of second group of electrode collection, calculate the DIELECTRIC CONSTANT of fluid-mixing _m

B. in the polyphasic flow with cross section oil content α _o, cross section water percentage α _w, void fraction α _gEquivalence contains rate, known oil phase DIELECTRIC CONSTANT for the volume of Oil, Water, Gas respectively _o, the water DIELECTRIC CONSTANT _wAnd gas phase DIELECTRIC CONSTANT _g, according to formula

And φ _o+ φ _w+ φ _g=1 calculates the oil phase volume contains rate φ _o, the water volume contains rate φ _wContain rate φ with gaseous phase volume _g, ρ in the formula _o, ρ _w, ρ _gBe oil phase density, water density, density of gas phase;

C. previous step is obtained to such an extent that each phase cross section c step and d of containing rate substitution step 3) goes on foot determined two relational expressions, in calculate total mass flow rate, each phase mass rate and each phase quality and contain rate;

D. according to formula

Calculate the total volumetric flow rate Q of fluid-mixing _v, in the formula, ρ _mBe the fluid hybrid density;

E. according to formula

Calculate the oil phase volume flow Q _Vo, the water volume flow Q _VwWith gas phase volume flow rate Q _Vg

F. according to formula

Calculate oil phase flow velocity V _o, aqueous phase flow rate V _wWith gas phase flow velocity V _g, in the formula, A ₀Be the circulation area of annular free air space, α _oBe cross section oil content, α _wBe cross section water percentage, α _gBe void fraction.

Beneficial effect of the present invention and advantage are as follows:

1, the annular free air space of cone throttling element and duct wall formation carries out rectification to the polyphasic flow fluid-mixing, flow in the circular passage of formation standard, channel inner pressure is stablized and pressure is linear decline along axis, makes the repeatability of measurement and degree of accuracy raising become possibility; Reliable mounting structure flexibly can be changed the cone throttling element of different-diameter ratio according to the different measuring object, with the scope of application of expansion measurement.

2, the present invention is by introducing flow pattern anticipation device or directly adopting electric sensor and the simultaneously-measured advantage of differential pressure (flow) sensor, utilization contains rate and predicts the outcome and carry out classification, identification and the anticipation of flow pattern with the volume forecasting result, when adopting arc-shaped electrode as electric sensor, also can utilize the differentiation that the rate distributed intelligence realizes instantaneous flow pattern that contains of its measurement, adopt the accurate measurement of different computation model implementation procedure parameters according to variations in flow patterns.

3, the polyphasic flow fluid-mixing flows through the cone throttling element and produces in annular free air space and shrink pressure drop Δ p, and produce permanent crushing δ p in pressure recovery place of cone downstream certain distance, adopt contraction pressure drop Δ p and permanent crushing δ p to make differential pressure signal, comprise flowing information more fully, can utilize two differential pressure models to obtain procedure parameters such as the flow of polyphasic flow and phase content simultaneously.

The form of the electricity sensitive sensor that 4, measuring method of the present invention adopted can be diversified, as ring electrode, arc-shaped electrode etc., adopting arc-shaped electrode can be the form of many measurement space combinations with the average measurement characteristic changing of ring electrode, improve the local measurement susceptibility, and then improved overall measurement accuracy; The character variation of electricity sensitive sensor, double sections electrode comprise the electrode of measuring the fluid-mixing conductivity and the electrode of measuring the fluid-mixing specific inductive capacity, can measure impedance information simultaneously, the measurement range of expanding unit; The energisation mode variation of electricity sensitive sensor, as voltage drive and current excitation etc., internal and external electrode all can be used as exciting electrode.

Description of drawings

The following drawings has been described embodiment chosen of the present invention, is exemplary drawings and non exhaustive or restricted, wherein:

The long waist inner cone of the double sections impedance type multiphase flow measurement device front view that Fig. 1 measuring method of the present invention adopts;

The long waist inner cone of the double sections impedance type multiphase flow measurement device lateral cross section view that Fig. 2 measuring method of the present invention adopts;

The conical throttling gear front view that Fig. 3 measuring method of the present invention adopts;

Fig. 4 (a) is vertical C-C cross section view of the cone throttling element of measuring method employing of the present invention; (b) be the vertical view of cone; (c) be the horizontal B-B cross section view of cone;

The vertical view of second kind of sensor that Fig. 5 (a) measuring method of the present invention adopts (b) is its horizontal B-B cross section view; (c) be its vertical A-A cross section view; (d) be its horizontal C-C cross section view, wherein, interior electrode is the double sections ring electrode, and dispatch from foreign news agency is double sections 8 arc-shaped electrodes very.

The vertical view of the third sensor that Fig. 6 (a) measuring method of the present invention adopts (b) is its horizontal B-B cross section view; (c) be its vertical A-A cross section view; (d) be its horizontal C-C cross section view, wherein, internal and external electrode is double sections 8 arc-shaped electrodes;

The vertical view of the 4th kind of sensor that Fig. 7 (a) measuring method of the present invention adopts (b) is its horizontal B-B cross section view; (c) be its vertical A-A cross section view; (d) be its horizontal C-C cross section view, wherein, internal and external electrode is a cross section ring electrode one cross section 8 arc-shaped electrodes;

The vertical view of the 5th kind of sensor that Fig. 8 (a) measuring method of the present invention adopts (b) is its horizontal B-B cross section view; (c) be its vertical A-A cross section view; (d) be its horizontal C-C cross section view, wherein, interior electrode is single wide electrode, and dispatch from foreign news agency is the double sections ring electrode very;

The computing unit structural drawing that Fig. 9 adopts for the present invention;

Signal in Figure 10 computing unit takes place and the mode selection module structural drawing;

Signal condition modular structure figure in Figure 11 computing unit;

AD in Figure 12 computing unit gathers and the signal pre-processing module structural drawing;

Figure 13 measuring method process flow diagram of the present invention;

The number in the figure explanation: a is used in two different cross sections respectively, and b distinguishes, and a among the label 16-21, b represent to be distributed in the electrode and the electrode that is distributed on the B cross section on a cross section.

Embodiment

Below describe in detail making and operate step of the present invention, be intended to describe as embodiments of the invention, is not to be can be manufactured or unique form of utilizing, should comprise within the scope of the invention other embodiment that can realize identical function yet.

Describe the preferred embodiments of the present invention in detail below in conjunction with Figure of description.

1-4 with reference to the accompanying drawings, the measurement mechanism that the present invention adopts comprises that two ends have the pipeline 1 of flange 2, a cone throttling element 7, three pressure ports: upstream pressure port 3, middle pressure port 4, downstream pressure port 5, two transmitters: shrink pressure drop differential pressure transmitter 24, permanent crushing differential pressure transmitter 25, be installed in the electricity sensitive sensor on annular free air space 12 corresponding pipelines 1 and the cone waist 9: external electrode 17, interior electrode 16, computing unit 27 and other accessory structures.Cone throttling element 7 be on the basis of traditional inner cone with throat downstream equal diameter lengthening form cone waist 9 and get, cone throttling element 7 is by support 11 and the support fixture splice 6 coaxial pipe centerline places that are installed in, and can change the cone 7 of different throttling ratios with the expansion measurement range according to measured matter and operating mode, cone throttling element 7 is included in the entrance 8 that the flow direction diameter increases gradually, cone waist 9 that diameter is constant and diameter are decreased to zero outlet section 10 gradually, when polyphasic flow fluid-mixing 13 flows through this cone throttling element 7, one of circulation area experience is dwindled gradually, and the process that enlarges gradually after in certain distance, stablizing, during polyphasic flow fluid-mixing 13 process cone entrances 8, circulation area reduces reposefully, speed is increased regularly, static pressure is corresponding to be reduced, along with circulation area reduces, the rate of change of speed is big more; When fluid flows through cone waist 9 places, owing to inertia effect continues to quicken, the fluid that continues to quicken can be adjusted because of the rectified action of cone throttling element 7 again, flowed in its circular passage that forms standard at annular free air space 12 places.Cone throttling element 7 adopts resistant material (high performance metal material, industrial ceramics or other corrosion-resistant materials) in case the corrosion of fluid stopping body.In cone throttling element 7 upstreams, annular free air space 12 and downstream pressure recover corresponding tube wall pressure port are set, because cone throttling element 7 is coaxially installed in the pipeline 1, when fluid-mixing 13 flows through, can produce with middle pressure port 4 and shrink pressure drop Δ p at the upstream of cone throttling element 7 pressure port 3, produce permanent crushing δ p at upstream pressure port 3 and pressure recovery place downstream pressure port 5, shrink pressure drop transmitter 24 and permanent crushing transmitter 25 by pressure guiding pipe 23 these two pairs of differential pressure signals of collection, the electrical quantity signal that produces is transferred to computing unit 27 by transducer signal line 26.

In the measurement mechanism that the present invention adopts, the electricity sensitive sensor that is embedded on cone waist 9 and the pipeline 1 can form symmetrical electric field in annular free air space 12, by measure the fluid electrical parameter (as electricity lead, electric capacity, specific inductive capacity etc.) determine that each phase (component) contains rate.Electricity sensitive sensor of the present invention comprises two groups of electrodes on the different cross section that is distributed in annular free air space place, and wherein one group is used to measure the fluid-mixing conductivity, and another group is used to measure the fluid-mixing specific inductive capacity.Electrode and external electrode in every group of electrode includes.Interior electrode 16 is embedded in cone waist 9 top layers, and external electrode 17 is embedded in pipeline 1 inwall top layer, and electrode and the corresponding top layer that is embedded into body maintain an equal level, and promptly electrode can not produce disturbance to polyphasic flow fluid-mixing 13.Electrode 16 is the metal ring electrode in the double sections, comprise interior electrode 16a that measures the fluid-mixing conductivity and the interior electrode 16b that measures the fluid-mixing specific inductive capacity, link to each other by separately circuit in the signal wire passage 22 of cone throttling element 7 and support 11 inside and computing unit 27 by terminals 18a separately and 18b, signal wire 20a and 20b; Double sections external electrode 17 is the circular metal electrode with interior electrode 16 same widths and thickness, comprise external electrode 17a that measures the fluid-mixing conductivity and the external electrode 17b that measures the fluid-mixing specific inductive capacity, link to each other by separately circuit in terminals 19a separately and 19b, signal wire 21a and 21b and the computing unit 27.External electrode 17a in the present embodiment, 17b is as exciting electrode, energisation mode is a current excitation, interior electrode 16a, insulation and ground connection between 16b and the cone throttling element 7, measure the voltage signal between internal and external electrode, measuring-signal is by signal wire 20a, 20b, 21a, 21b is transferred to computing unit 27, differential pressure signal simultaneous with above-mentioned obtains the polyphasic flow procedure parameter according to computation model, as a minute phase content (cross section phase content, the quality phase content), the phase-splitting flow velocity, volumetric flow rate and mass rate, then the Long-distance Control interface is arrived in output signal 28 demonstrations or teletransmission, finished the measurement of total system.Measurement mechanism of the present invention is installed in the actual pipeline by flange, and the diameter of concrete pipeline and length is border situation and deciding factually.

Double sections electrode form and array mode among the present invention have diversified characteristics, are 0 ° to 180 ° as electrode center of circle angular region; Electrode width scope 0mm is to L/2 (cone throttling element waist length L); Internal and external electrode can be that identical shaped electrode can be a difformity electrode etc. also, so the electrode structure of this device has various ways, and Fig. 2, Fig. 5-8 has described wherein five kinds of typical array modes.

Fig. 2 has described first kind of sensor construction of the measurement mechanism of the present invention's employing: internal and external electrode is the double sections ring electrode cross section view (preferred electrode structure) of same widths, one in the internal and external electrode as another ground connection of exciting electrode, and energisation mode is current excitation or voltage drive.

Other sensor construction of the measurement mechanism that the present invention adopts is with first kind of difference, has proposed other several preferred embodiments of electrode structure.

Fig. 5 has described second kind of sensor construction: dispatch from foreign news agency is double sections 8 arc-shaped electrodes very, comprise electrode 17a that measures the fluid-mixing conductivity and the electrode 17b that measures the fluid-mixing specific inductive capacity, interior electrode is a same widths double sections ring electrode, comprises electrode 16a that measures the fluid-mixing conductivity and vertical view (a), transverse cross sectional view (b, d), the longitudinal profile view (c) of measuring the electrode 16b of fluid-mixing specific inductive capacity.The structure of electrode, fixed form, signal wire etc. are consistent with interior electrode shown in the embodiment 1 in this array configuration; Each circular arc external electrode 17a and 17b all are connected in the computing unit 27 separately circuit by terminals 19a and 19b and signal wire 21a and 21b separately.The preferred central angle of external electrode is 11 °, according to experiment conclusion as can be known, and 4 °-40 ° of single cross section 8 arc-shaped electrode central angle ranges of choice, and arc-shaped electrode number variable (central angle changes thereupon).One in the internal and external electrode as another ground connection of exciting electrode.Energisation mode is current excitation or voltage drive.

Fig. 6 has described the third sensor construction: dispatch from foreign news agency is double sections 8 arc-shaped electrodes very, comprise electrode 17a that measures the fluid-mixing conductivity and the electrode 17b that measures the fluid-mixing specific inductive capacity, interior electrode is same widths double sections 8 arc-shaped electrodes, comprises electrode 16a that measures the fluid-mixing conductivity and vertical view (a), transverse cross sectional view (b, d), the longitudinal profile view (c) of measuring the electrode 16b of fluid-mixing specific inductive capacity.Internal and external electrode number unanimity in this array configuration, and the position is corresponding one by one, electrode 16a and 16b in each circular arc are linked to each other by separately circuit in the signal wire passage 22 of cone throttling element 7 and support 11 inside and computing unit 27 by terminals 18a separately and 18b, signal wire 20a and 20b; Each circular arc external electrode 17a and 17b all are connected in the computing unit 27 separately circuit by terminals 19a and 19b and signal wire 21a and 21b separately.The preferred central angle of inside and outside circle arc-shaped electrode is 11 °, according to experiment conclusion as can be known, and 4 °-40 ° of single cross section 8 arc-shaped electrode central angle ranges of choice, and arc-shaped electrode number variable (central angle changes thereupon).One in the internal and external electrode as another ground connection of exciting electrode.Energisation mode is current excitation or voltage drive.

Fig. 7 has described the 4th kind of sensor construction: dispatch from foreign news agency is the double sections ring electrode very, comprise single cross section ring electrode 17a that measures the fluid-mixing conductivity and the single cross section 8 arc-shaped electrode 17b that measure the fluid-mixing specific inductive capacity, interior electrode is that same widths is measured single cross section ring electrode 16a of fluid-mixing conductivity and vertical view (a), transverse cross sectional view (b, d), the longitudinal profile view (c) of the single cross section 8 arc-shaped electrode 16b that measure the fluid-mixing specific inductive capacity.Internal and external electrode number unanimity in this array configuration, and the position is corresponding one by one, electrode 16b in electrode 16a and each circular arc in the annular is linked to each other by separately circuit in the signal wire passage 22 of cone throttling element 7 and support 11 inside and computing unit 27 by terminals 18a separately and 18b, signal wire 20a and 20b; Annular external electrode 17a and each circular arc external electrode 17b all are connected in the computing unit 27 separately circuit by terminals 19a and 19b and signal wire 21a and 21b separately.The preferred central angle of inside and outside circle arc-shaped electrode is 11 °, according to experiment conclusion as can be known, and 4 °-40 ° of single cross section 8 arc-shaped electrode central angle ranges of choice, and arc-shaped electrode number variable (central angle changes thereupon).One in the internal and external electrode as another ground connection of exciting electrode.Energisation mode is current excitation or voltage drive.

Fig. 8 has described the 5th kind of sensor construction: dispatch from foreign news agency is the double sections ring electrode very, comprise electrode 17a that measures the fluid-mixing conductivity and the electrode 17b that measures the fluid-mixing specific inductive capacity, interior electrode is that width is vertical view (a), transverse cross sectional view (b, d), the longitudinal profile view (c) of sensor device of the single wide electrode 16 of L.In this array configuration, electrode 16 in the wide annular is linked to each other with computing unit 27 by the signal wire passage 22 in cone throttling element 7 and support 11 inside by terminals 18, signal wire 20; Annular external electrode 17a and 17b all with 21b are connected computing unit 27 with 19b with signal wire 21a by terminals 19a separately.Dispatch from foreign news agency is exciting electrode very, and interior electrode grounding, energisation mode are current excitation or voltage drive.

More than be five kinds of typical combination modes, other array configurations can make up as the basis.When being 0 ° (electrodeless) as the external electrode central angle, duct wall ground connection, the form of interior electrode can be double sections ring electrode or many arc-shaped electrodes of double sections or the many arc-shaped electrodes of single cross section ring electrode and single cross section, and interior electrode structure, fixed form, signal wire etc. are consistent with above typical combination mode implementation method; When being 0 ° (electrodeless) as interior electrode central angle, cone throttling element ground connection, the form of external electrode can be double sections ring electrode or many arc-shaped electrodes of double sections or the many arc-shaped electrodes of single cross section ring electrode and single cross section, and external electrode structure, fixed form, signal wire etc. are consistent with above typical combination mode implementation method.

Computing unit is shown in accompanying drawing 9～12: mainly be made up of signal generation and mode selection module, signal condition module, AD collection and signal pre-processing module, computer bus and CPU or computing machine, as shown in Figure 9.Wherein:

Signal generation and mode selection module concrete structure mainly are made up of circuit such as computer bus, logic control circuit, signal generation apparatus, constant voltage or constant current source and electrode channel selections as shown in Figure 10.Computer bus is mainly finished communicating by letter and data transmission of data acquisition system (DAS) and CPU or computing machine; The logic control circuit major function is that control signal takes place and electrode channel is selected the working forms of circuit, realizes the selection of system incentive strategy and mode of operation, and and signal condition module and AD collection and signal pre-processing module between co-ordination; It is the pumping signal of the controlled various ways of realization frequency that signal generating circuit selects major function, for example single, double polarity pulse signal and sinusoidal signal etc.; Constant voltage or constant-current source circuit adopt voltage control voltage source (VCVS) or voltage control current source (VCCS) scheme, and mainly the pumping signal that signal generating circuit is produced is converted to amplitude and adjustable constant voltage or the current signal of phase place; Electrode channel selects circuit to adopt the digital simulation switch chip, transmits passage according to working method and policy logic control circuit foundation excitation with measuring-signal.

Signal condition module concrete structure mainly is made up of electrode drive circuit, logic control circuit and signal amplification circuit as shown in Figure 11.Electrode drive circuit adopts the analog drive circuit technology, improves the load capacity of system and reduces the influence of spurious signals such as contact resistance, electric capacity and inductance to measured signal; The section selection module is selected the digital simulation switch chip for use, realizes the double sections alternation by logic control circuit; Amplifying circuit is made of high-precision meter operational amplifier or programmable amplifier chip, but the induced signal that electrode (adjacent electrode) is upward small in the pair cross-section and the transmission signal of differential pressure transmitter amplify the raising signal to noise ratio (S/N ratio).The setting of the logical address of logic control circuit realization amplifying circuit and the selection output of enlargement factor, and the logic communication between responsible and AD collection and signal pre-processing module and signal generation and the mode selection module.

AD collection and signal pre-processing module structure are as shown in Figure 12.Mainly form by AD converter array, digital signal processing and logic control circuit, data storage computer bus etc.The AD converter array circuit adopts the AD conversion chip to constitute, and can convert tested simulating signal and the differential pressure signal of passing back through the signal condition module to digital signal.Digital signal processing and logic control circuit realize digital signal filtering, separate and be in harmonious proportion function such as storage control, and the data after will handling are transferred to CPU or computer module by computer bus.

The data acquisition system (DAS) course of work that the present invention adopts: at first CPU or computer module carry out initialization operation by computer bus to signal generation and mode selection module, comprise the exciting current selection, excitation frequency is selected and excitation/measurement strategies selection etc., and is realized by logic control circuit.Pumping signal is alternately set up responsive respectively through the cross section handover module in cross section, two circular passages, change the differential pressure signal that electrode voltage changes and differential pressure transmitter is passed back that causes by dielectric distribution in the field and pass through the cable parallel transfer to the signal condition module, electric signal after the conditioning enters AD and gathers and signal pre-processing module, finish analog to digital conversion and the digital signal after the conversion is carried out processing such as filtering and demodulation by digital signal processing and logic control circuit control AD chip, effective information after the processing is conveyed into CPU or computing machine by the computer bus interface, combines analysis and the processing of carrying out measurement data with measurement model.

Below multiphase flow measurement method of the present invention is described:

(1). gather two pairs of differential pressure signals that produce by the cone throttling element: shrink pressure drop differential pressure signal Δ p and permanent crushing differential pressure signal δ p;

(2). utilize the electricity sensitive sensor to gather electric signal;

(3). utilize and shrink pressure drop Δ p and the two differential pressure measurement models of permanent crushing δ p formation single-unit stream device, draw the relational expression between total mass flow rate, each phase mass rate, each phase quality phase content and the phase content.

Under the phase-splitting flow model, suppose that promptly each flows each phase-splitting mutually is distinct incompressible fluid, and the two-phase efflux coefficient is identical, the pressure drop that each pressure drop when flowing through throttling element mutually equals fluid-mixing when flowing through throttling element, in flow process, do not undergo phase transition and expand, polyphasic flow fluid-mixing pressure drop expression formula is, is example with oil-gas-water three-phase flow under the low pressure operating mode, regards oil-water two-phase flow as liquid phase:

$\sqrt{\frac{\mathrm{\Δp}}{\mathrm{\Δ}{p}_g}}=\sqrt{\frac{\mathrm{\Δ}{p}_l}{\mathrm{\Δ}{p}_g}}+1---\left(1\right)$

In the formula, Δ p _lWith Δ p _gRepresent that respectively the contraction pressure drop that produces when liquid and gas in the oil-gas-water three-phase flow flow through restricting element separately with total volumetric flow rate, Δ p are the contraction pressure drop that three-phase stream potpourri produces when flowing through throttling element.Through deriving and corresponding correction can obtain two-phase flow calculating formula under the phase-splitting flow model:

In the formula:

ε is an expansibility factor, for incompressible fluid ε=1;

X contains rate for the gas phase quality;

W _mTotal mass flow rate for fluid-mixing;

C ₁For shrinking pressure drop Δ p is the efflux coefficient that differential pressure signal calibrates;

β is the equivalent diameter ratio of flow area,

A ₀Be the circulation area of annular free air space,

D is the diameter of cone waist; D is an internal diameter of the pipeline;

Be the two-phase flow multiplier, χ is Lockhart-Martinelli (L-M) parameter;

ρ _gBe density of gas phase, ρ ₁Be density of liquid phase;

Directly use the phase-splitting flow model and tend to cause bigger error, the present invention is according to the Bizon calculating formula

Carry out measurement model and derive, wherein a, b are and cone shape, the parameter that the pressure position is relevant.Can obtain for two kinds of different differential pressure signals:

Wherein:

Be the two-phase flow multiplier; W _Mtp1, W _Mtp2Be defined as the equivalent mass flow, its size shrinks pressure drop Δ p for supposition and permanent crushing δ p all produces the flow value that calculates, W by gas phase _MgBe gas phase mass flow, subscript 1 and 2 is represented respectively and is utilized contraction pressure drop Δ p and permanent crushing δ p to bring the formula result calculated into.Hence one can see that:

$W_{\mathrm{mtp}1}=\frac{\mathrm{\&epsiv;}{C}_1{\mathrm{<figure-callout\; id="0"\; label="A"\; filenames="HDA0000048286350000011.png"\; state="\{\{state\}\}">A</figure-callout>}}_0}{\sqrt{1-{\mathrm{\&beta;}}^4}}\sqrt{2\mathrm{\&Delta;p}{\mathrm{\&rho;}}_g};$ $W_{\mathrm{mtp}2}=\frac{\mathrm{\&epsiv;}{C}_{2}A}{\sqrt{1-{\mathrm{\&beta;}}^4}}\sqrt{2\mathrm{\&delta;p}{\mathrm{\&rho;}}_g}---\left(4\right)$

In the formula:

C ₁For shrinking pressure drop Δ p is the efflux coefficient that differential pressure signal calibrates, C ₂For permanent crushing δ p is the efflux coefficient that differential pressure signal calibrates;

A ₀Be the circulation area of annular free air space, A is the pipeline circulation area;

Above parameter is known or obtains by demarcating, and can calculate equivalent mass flow W according to formula (4) _Mtp1, W _Mtp2Two formulas in the formula (3) are compared, and obtained characteristic parameter a by calibration experiment ₁, b ₁, a ₂, b ₂So, can obtain L-M parameter χ, and then obtain that the gas phase quality contains rate x, the liquid phase quality contains rate 1-x, gas phase mass flow W _g, liquid phase mass rate W _l, total mass flow rate W _mWith cross section oil content α _o, cross section water percentage α _w, void fraction α _gBetween relational expression:

$x=\frac{\sqrt{\frac{{\mathrm{\&rho;}}_g}{{\mathrm{\&rho;}}_l}}}{(\frac{b_1{W}_{\mathrm{mtp}2}-b_2{W}_{\mathrm{mtp}1}}{a_2{W}_{\mathrm{mtp}1}-a_1{W}_{\mathrm{mtp}2}}+\sqrt{\frac{{\mathrm{\&rho;}}_g}{{\mathrm{\&rho;}}_l}})}---\left(5\right)$

$W_{\mathrm{mg}}=\frac{\mathrm{\&epsiv;}{C}_1{\mathrm{<figure-callout\; id="0"\; label="A"\; filenames="HDA0000048286350000011.png"\; state="\{\{state\}\}">A</figure-callout>}}_0}{\sqrt{1-{\mathrm{\&beta;}}^4}}\&CenterDot;\frac{\sqrt{2\mathrm{\&Delta;p}{\mathrm{\&rho;}}_g}}{a_1\frac{1-x}{x}\sqrt{{\mathrm{\&rho;}}_g/{\mathrm{\&rho;}}_l}+{\mathrm{<figure-callout\; id="1"\; label="b"\; filenames="HDA0000048286350000012.png"\; state="\{\{state\}\}">b</figure-callout>}}_1}$

$W_{\mathrm{ml}}=\frac{\mathrm{\&epsiv;}{C}_1{\mathrm{<figure-callout\; id="0"\; label="A"\; filenames="HDA0000048286350000011.png"\; state="\{\{state\}\}">A</figure-callout>}}_0}{\sqrt{1-{\mathrm{\&beta;}}^4}}\&CenterDot;\frac{\sqrt{2\mathrm{\&Delta;p}{\mathrm{\&rho;}}_g}}{a_1\sqrt{{\mathrm{\&rho;}}_g/{\mathrm{\&rho;}}_l}+b_1\frac{x}{1-x}}---\left(6\right)$

$W_m=\frac{\mathrm{\&epsiv;}{C}_1{\mathrm{<figure-callout\; id="0"\; label="A"\; filenames="HDA0000048286350000011.png"\; state="\{\{state\}\}">A</figure-callout>}}_0}{\sqrt{1-{\mathrm{\&beta;}}^4}}\&CenterDot;\frac{\sqrt{2\mathrm{\&Delta;p}{\mathrm{\&rho;}}_g}}{a_1(1-x)\sqrt{{\mathrm{\&rho;}}_g/{\mathrm{\&rho;}}_l}+b_{1}x}$

In the formula:

a ₁, b ₁For being the test parameters that sample data is demarcated to shrink pressure drop Δ p;

ρ _lHybrid density for liquid phase under the working condition;

Under the low pressure operating mode, the fluid hybrid density ρ of oil-gas-water three-phase flow _mCan be expressed as:

ρ _m＝α _oρ _o+α _wρ _w+α _gρ _g≈α _oρ _o+α _wρ _w＝(1-α _g)ρ _l (7)

In the formula:

ρ _o, ρ _w, ρ _g, ρ _lBe oil phase density, water density, density of gas phase and density of liquid phase;

α _o, α _w, α _gBe cross section oil content, cross section water percentage, void fraction;

So under the low pressure operating mode, the hybrid density ρ of liquid phase _lCan be expressed as:

${\mathrm{\&rho;}}_l=\frac{{\mathrm{\&alpha;}}_o}{1-{\mathrm{\&alpha;}}_g}{\mathrm{\&rho;}}_o+\frac{{\mathrm{\&alpha;}}_w}{1-{\mathrm{\&alpha;}}_g}{\mathrm{\&rho;}}_w---\left(8\right)$

Utilize this pair differential pressure model can draw total mass flow rate, each phase mass rate, each phase quality phase content and the cross section oil content α of fluid-mixing _o, cross section water percentage α _w, void fraction α _gRelational expression, then the total volumetric flow rate of fluid-mixing can be expressed as:

$Q_v=\frac{W_m}{{\mathrm{\&rho;}}_m}---\left(9\right)$

In the formula:

Q _vTotal volumetric flow rate for fluid-mixing;

ρ _mHybrid density for fluid under the working condition;

The total volumetric flow rate formula is put out the expression formula of the total volumetric flow rate of fluid in order in differential pressure signal by differential pressure flowmeter and the pipeline:

$Q_v=\frac{\mathrm{\&epsiv;}\&CenterDot;{\mathrm{<figure-callout\; id="1"\; label="C"\; filenames="HDA0000048286350000012.png"\; state="\{\{state\}\}">C</figure-callout>}}_1}{\sqrt{1-{\mathrm{\&beta;}}^4}}{\mathrm{<figure-callout\; id="0"\; label="A"\; filenames="HDA0000048286350000011.png"\; state="\{\{state\}\}">A</figure-callout>}}_0\sqrt{\frac{2\mathrm{\&Delta;p}}{{\mathrm{\&rho;}}_m}}---\left(10\right)$

Simultaneous formula (7), (9), (10) obtain hybrid density ρ _mAnd shrink the expression formula between the differential pressure Δ p:

${\mathrm{\&alpha;}}_o{\mathrm{\&rho;}}_o+{\mathrm{\&alpha;}}_w{\mathrm{\&rho;}}_w+{\mathrm{\&alpha;}}_g{\mathrm{\&rho;}}_g=\frac{W_m^2(1-{\mathrm{\&beta;}}^4)}{2{(\mathrm{\&epsiv;}\&CenterDot;C_1{A}_0)}^2\mathrm{\&Delta;p}}---\left(11\right)$

For the gas of oil product, water and known static pressure and the temperature determined, can think the oil phase density p _o, the water density p _wAnd density of gas phase ρ _gFor known, and known

α _o+α _w+α _g＝1 (12)

Therefore wherein contain rate and can draw fluid hybrid density ρ in the cross section of a certain phase if record oil gas water three phase _m

(4). analyze differential pressure signal and electric signal, carry out classification, identification and the anticipation of flow pattern, judging object fluid external phase is conductive phase (water) or non-conductive phase (gas phase or oil phase), right according to the corresponding potential electrode of the different choice of external phase then, if external phase is gas phase or oil phase, utilize the interior electrode 16b be distributed on the b cross section and the voltage signal between the external electrode 17b to calculate; If interior electrode 16a that external phase is water then utilize to be distributed on a cross section and the voltage signal between the external electrode 17a calculate.

The general step of flow pattern identification is: at first extract the eigenwert that can reflect variations in flow patterns from measurement data, utilize sorting algorithm that eigenwert is sorted out identification then, such as support vector machine, artificial neural network etc.The present invention is that example is carried out flow pattern identification with the support vector machine method, and concrete steps are as follows:

1, extracts image data eigenwert makeup time sequence in 5 seconds, from time series, extract three kinds of statistical nature composition characteristic vectors

Time series mean value

Represented the average energy that electric signal or differential pressure signal comprised of electricity sensitive sensor collection:

$\stackrel{\&OverBar;}{x}=\frac{1}{n}\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}{x}_i---\left(13\right)$

Wherein n is the eigenwert quantity in the time series, x _iBe single V _mValue.

Seasonal effect in time series standard deviation (S), reacted the degree of scatter of measuring-signal:

$S=\sqrt{\frac{1}{n-1}\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}{(x_i-\stackrel{\&OverBar;}{x})}^2}---\left(14\right)$

Seasonal effect in time series gradient (SK), reacted the seasonal effect in time series inclined degree:

$\mathrm{SK}=\frac{n}{(n-1)(n-2)}\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}{\left(\frac{x_i-\stackrel{\&OverBar;}{x}}{S}\right)}^3---\left(15\right)$

2, support vector machine (SVM) realizes distance minimization between class distance maximization and the class by setting up a lineoid, can be used as sorter and realizes flow pattern identification.The optimal classification function is

$f\left(x\right)=\mathrm{sgn}\{({\mathrm{\&omega;}}^{*}\&CenterDot;x)+b^{*}\}=\mathrm{sgn}\{\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}{a}_i^{*}{y}_{i}K(x_i\&CenterDot;x)+b^{*}\}---\left(16\right)$

In the formula, sgn () is-symbol function, ω ^*Be the normal vector of lineoid, b ^*Be the threshold value of classification,

Be optimum solution, y _iBe constraint condition, K (x _iX) be kernel function; Select kernel function according to actual needs.

3, with the input of proper vector, the data that collect are classified as SVM.The target of this patent flow pattern identification is water quality type flow pattern, makings type flow pattern and oily type flow pattern three major types, to support vector machine of every kind of flow pattern structure, output y _i∈ 1,1}, (i=1,2,3), then the output of 3 support vector machine is one 3 dimensional vectors, whether each representation in components sample to should flow pattern, (1 ,-1 ,-1) expression water quality type flow pattern, (1,1 ,-1) expression makings type flow pattern, the oily type flow pattern of (1 ,-1,1) expression.Select radially basic kernel function for use

Wherein ζ gets 0.05, and the support vector machine that trains can realize the identification of convection.

(5). utilize electric method to calculate each phase content.

Introduce electrical parameter measuring method measurement cross section and contain rate, comprise two kinds of electrical methods among the present invention, the one, by the specific inductive capacity of interior electrode 16b and external electrode 17b measurement fluid-mixing; The 2nd, by the conductivity of interior electrode 16a and external electrode 17a measurement fluid-mixing.Gather the electrical signal of the electricity sensitive sensor in two cross sections simultaneously, according to the flow pattern of step (three) differentiate result's (external phase whether conduct electricity) selection wherein a kind of measured value of method carry out subsequent treatment, so whether the present invention is not conducted electricity by continuous phase of multiphase flow to influence.Concrete principle is as follows: the electrical parameter of fluid 13 (as electricity lead, electric capacity, specific inductive capacity etc.) depend on each mutually shared ratio of fluid-mixing, and can set up each phase content and the relation of mixing electrical quantity by some computation models, as the electrical quantity in the Boyle model can by in the fluid-mixing each minute the phase fluid specific inductive capacity function representation.Discrete phase 15 is to be distributed in the liquid phase of being made up of profit two-phase fluid-mixing in the continuous gas phase 14, and then the specific inductive capacity of fluid-mixing 13 can use H-B (H-Bnon) formula to calculate:

$\sqrt{{\mathrm{\&epsiv;}}_m}={\mathrm{\&phi;}}_g\sqrt{{\mathrm{\&epsiv;}}_g}+(1-{\mathrm{\&phi;}}_g)({\mathrm{\&phi;}}_w\sqrt{{\mathrm{\&epsiv;}}_w}+{\mathrm{\&phi;}}_o\sqrt{{\mathrm{\&epsiv;}}_o})---\left(17\right)$

In the formula:

ε _o, ε _w, ε _g, ε _mBe respectively the specific inductive capacity of oil phase, water, gas phase, fluid-mixing;

φ _o, φ _w, φ _gThe volume that is respectively oil phase, water, gas phase contains rate;

The polyphasic flow middle section contains rate α and is difficult to direct measurement, and the average external volume of general available measuring section contains rate φ and replaces.Wherein the specific inductive capacity of oil phase and water can obtain by tabling look-up or demarcating, because the fluid-mixing specific inductive capacity is proportional to the electric capacity between internal and external electrode, and the electric capacity between internal and external electrode is proportional to the voltage magnitude between internal and external electrode, therefore can calculate the specific inductive capacity of fluid-mixing by the voltage signal between electrode 16b in measuring and the external electrode 17b, by simultaneous formula (11), (12), (17), and then the cross section that obtains oil gas water three phase contains rate α _o, α _w, α _gAnd total volumetric flow rate Q _v, the total mass flow rate, each phase mass rate and each the phase quality that calculate fluid-mixing according to formula (5), (6) contain rate.

When the water percentage in the fluid-mixing 13 was too high, the use of capacitance method was subjected to certain limitation, but electricity consumption this moment is led as tested electrical quantity.Because the gas phase conductivity is approximately zero, and liquid phase is a conducting medium, so the fluid mixed conductivity volume that depends primarily on liquid phase contains rate and distribution mutually.According to Maxwell resistivity approximation theory, then the conductivity of fluid-mixing 13 is:

${\mathrm{\&sigma;}}_m=\frac{2{\mathrm{\&alpha;}}_l}{3-{\mathrm{\&alpha;}}_l}\frac{2{\mathrm{\&alpha;}}_w}{3-{\mathrm{\&alpha;}}_w}{\mathrm{\&sigma;}}_w---\left(18\right)$

In the formula:

α _l, α _wBe liquid holdup and cross section water percentage;

σ _m, σ _wBe respectively oil gas water mixed conductivity and water conductivity;

Because the voltage magnitude between mixed conductivity and internal and external electrode is inversely proportional to, therefore, can calculates the conductivity of fluid-mixing, and then obtain cross section water percentage α by the voltage signal between electrode 16a in measuring and the external electrode 17a _wBy simultaneous formula (11), (12), (18), and then the cross section that obtains oil gas water three phase contains rate α _o, α _w, α _gAnd total volumetric flow rate Q _v, the total mass flow rate, each phase mass rate and each the phase quality that calculate fluid-mixing according to formula (5), (6) contain rate.

The definition that contains rate according to volume can calculate each phase volume flow of oil gas water:

Q _vo＝φ _oQ _v

Q _vw＝φ _wQ _v (19)

Q _vg＝φ _gQ _v

In the formula:

φ _o, φ _w, φ _gFor oil phase, water, gaseous phase volume contain rate;

Q _Vo, Q _Vw, Q _Vg, Q _vBe oil phase, water, gas phase volume flow rate and total volumetric flow rate;

Each phase content is according to the phase velocity definition:

$V_o=\frac{Q_{\mathrm{vo}}}{{\mathrm{\&alpha;}}_{\mathrm{<figure-callout\; id="0"\; label="o\; A"\; filenames="HDA0000048286350000011.png"\; state="\{\{state\}\}">o</figure-callout>}}{A}_{}{}_0}$

$V_w=\frac{Q_{\mathrm{vw}}}{{\mathrm{\&alpha;}}_w{A}_0}---\left(20\right)$

$V_g=\frac{Q_{\mathrm{vg}}}{{\mathrm{\&alpha;}}_{\mathrm{<figure-callout\; id="0"\; label="g\; A"\; filenames="HDA0000048286350000011.png"\; state="\{\{state\}\}">g</figure-callout>}}{A}_{}{}_0}$

In the formula:

V _o, V _w, V _gBe oil phase flow velocity, aqueous phase flow rate, gas phase flow velocity;

α _o, α _w, α _gBe cross section oil content, cross section water percentage, void fraction.

Claims (1)

1. multiphase flow measurement method based on the long waist inner cone of double sections impedance type sensor, the sensor that adopts comprises segment of cone stream part, contraction pressure drop differential pressure transmitter, permanent crushing differential pressure transmitter, the electricity sensitive sensor, described cone throttling element is a kind of long waist inner cone restriction device, by the leading portion cone, constitute for three sections as stage casing column, the back segment cone of cone waist, by the coaxial pipeline center of being fixed in of support, form annular free air space with the tube wall of pipeline; Two pressure ports of described contraction pressure drop differential pressure transmitter, one is arranged on cone throttling element upstream end, and another is arranged on annular free air space place or cone afterbody; Two pressure ports of described permanent crushing differential pressure transmitter are separately positioned on recovery place of cone throttling element upstream and downstream pressure; Described electricity sensitive sensor comprises first group and the second group electrode on the different cross section that is distributed in annular free air space place, and first group of electrode is used to detect the fluid-mixing conductivity, and second group is used to detect the fluid-mixing specific inductive capacity; Every group of electrode is made of electrode in one or more and one or more external electrode, and interior electrode is fixed on cone waist surface, and external electrode is fixed on inner-walls of duct; During measurement, as excitation/potential electrode and ground-electrode, this measuring method comprises the following steps: respectively for each interior electrode of gating and its corresponding external electrode

1) gathers two pairs of differential pressure signals that produce by the cone throttling element: shrink pressure drop differential pressure signal Δ p and permanent crushing differential pressure signal δ p;

2) utilize the electricity sensitive sensor to gather electric signal;

3), obtain total mass flow rate, each phase mass rate, each phase quality and contain the relational expression between rate and the phase content according to two differential pressure models of following single throttling element:

A. according to formula With

Calculate equivalent mass flow W _Mtp1, W _Mtp2, in the formula, ε is an expansibility factor, C ₁For shrinking pressure drop Δ p is the efflux coefficient that differential pressure signal calibrates, C ₂For permanent crushing δ p is the efflux coefficient that differential pressure signal calibrates, A ₀Be the circulation area of annular free air space, A is the pipeline circulation area, and β is the equivalent diameter ratio of flow area, ρ _gBe density of gas phase;

B. with formula

Compare, calculate L-M parameter χ, in the formula,

Be two-phase flow multiplier, W _MgBe gas phase mass flow, a ₁, b ₁, a ₂, b ₂Be the rating test parameter;

C. according to formula

Obtain that the gas phase quality contains rate x, the liquid phase quality contains rate 1-x and cross section oil content α _o, cross section water percentage α _w, void fraction α _gBetween relational expression, in the formula,

Be two-phase flow multiplier, ρ _gBe density of gas phase, ρ ₁Be density of liquid phase,

α _oBe cross section oil content, α _wBe cross section water percentage, α _gBe void fraction, ρ _oBe oil phase density, ρ _wBe water density;

D. according to formula Calculate gas phase mass flow W _g, liquid phase mass rate W _l, total mass flow rate W _mWith cross section oil content α _o, cross section water percentage α _w, void fraction α _gBetween relational expression;

4) according to differential pressure signal and electric signal measurement data, carry out classification, the identification and judgement of flow pattern, judge that external phase is conductive phase or non-conductive phase in the fluid;

Whether be conductive phase according to external phase 5), adopt different computation models to calculate the procedure parameter of oil-gas-water three-phase flow, if external phase is conductive phase, the computation model of employing is as follows:

A. according to the voltage signal of first group of electrode collection, calculate the conductivity of fluid-mixing _m

B. known water conductivity _w, according to formula

α _l+ α _g=1 He Calculate cross section oil content α _o, cross section water percentage α _wWith void fraction α _g, in the formula, σ _mBe profit gas mixed conductivity;

C. previous step is obtained to such an extent that each phase cross section c step and d of containing rate substitution step 3) goes on foot determined two relational expressions, in calculate total mass flow rate, each phase mass rate and each phase quality and contain rate;

D. according to formula

Calculate the total volumetric flow rate Q of fluid-mixing _v, in the formula, ρ _mBe the fluid hybrid density;

E. according to formula

Calculate the oil phase volume flow Q _Vo, the water volume flow Q _VwWith gas phase volume flow rate Q _Vg

F. according to formula

Calculate oil phase flow velocity V _o, aqueous phase flow rate V _wWith gas phase flow velocity V _g

If external phase is non-conductive phase, the computation model of employing is as follows:

A. according to the voltage signal of second group of electrode collection, calculate the DIELECTRIC CONSTANT of fluid-mixing _m

B. in the polyphasic flow with cross section oil content α _o, cross section water percentage α _w, void fraction α _gEquivalence contains rate, known oil phase DIELECTRIC CONSTANT for the volume of Oil, Water, Gas respectively _o, the water DIELECTRIC CONSTANT _wAnd gas phase DIELECTRIC CONSTANT _g, according to formula

And φ _o+ φ _w+ φ _g=1 calculates the oil phase volume contains rate φ _o, the water volume contains rate φ _wContain rate φ with gaseous phase volume _g, ρ in the formula _o, ρ _w, ρ _gBe oil phase density, water density, density of gas phase;

C. previous step is obtained to such an extent that each phase cross section c step and d of containing rate substitution step 3) goes on foot determined two relational expressions, in calculate total mass flow rate, each phase mass rate and each phase quality and contain rate;

D. according to formula

Calculate the total volumetric flow rate Q of fluid-mixing _v, in the formula, ρ _mBe the fluid hybrid density;

E. according to formula

Calculate the oil phase volume flow Q _Vo, the water volume flow Q _VwWith gas phase volume flow rate Q _Vg

F. according to formula

Calculate oil phase flow velocity V _o, aqueous phase flow rate V _wWith gas phase flow velocity V _g, in the formula, A ₀Be the circulation area of annular free air space, α _oBe cross section oil content, α _wBe cross section water percentage, α _gBe void fraction.

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