CN201003962Y - Measurement device for air liquid two-phase bubble flow and volume air content rate - Google Patents

Abstract

The utility model discloses a measure device which is used for measuring the flux and the air voids per volume of the gas liquid two-phase bubble flow. Two pressure tapping holes which are symmetric with the whirlpool generator are arranged on the wall of the measure tube, which is inside certain area of the vortex shedding flow meter whirlpool generator lower course which is arranged inside the gas liquid two-phase bubble flow. A differential pressure pickup is used for measuring the differential pressure of the two pressure tapping holes. Then the frequency and the range of the differential pressure signal are gained through a signal disposing circuit and are counted with the relative formula of the gas liquid two-phase flow, and finally the flux and the air voids per volume of the gas liquid two-phase bubble flow is gained. Measuring the flux and the air voids per volume of the gas liquid two-phase bubble flow by utilizing only one vortex shedding flow meter, the utility model has the advantages that the measuring part of the utility model has simple structure, with no movable element and low cost; the signal disposing part of the utility model is fast, accurate and convenient; and the utility model is able to satisfy the on line measuring demand of the industry.

Description

Gas-liquid two-phase bubbly flow flow and gas volume fraction measurement mechanism

Technical field

The utility model relates to a kind of gas-liquid two-phase bubbly flow flow and gas volume fraction measurement mechanism.

Background technology

Biphase gas and liquid flow is present in the commercial production engineerings such as oil, chemical industry, the energy, electric power widely, measures its parameter accurately for safety, environmental protection, control with energy-conservationly all have great significance.Since biphase gas and liquid flow than single-phase flow not only the flow characteristics complexity many, and alternate interfacial effect and the relative velocity of existing causes the difficulty of parameter detecting bigger.For this reason, the vast researcher of countries in the world has been done a large amount of research work.Study more measuring method and relate to new technology more, as the active tracer technique of radiant rays technology, optical fiber technology, pulsed neutron etc., it is to use traditional single-phase flow instrument (as orifice plate, venturi etc.) and biphase gas and liquid flow model to carry out Multi-parameter Combined Tool and detect that a lot of research work are also arranged.The detection technique of these biphase gas and liquid flow parameters and method all also are in the laboratory applications conceptual phase, and commercial industrial instrument is for counting also seldom.No matter the detection of biphase gas and liquid flow parameter all still belongs to an exploratory development field that urgency is to be developed at home or in the world.

Summary of the invention

The purpose of this utility model provides a kind of gas-liquid two-phase bubbly flow flow and gas volume fraction measurement mechanism.

Gas-liquid two-phase bubbly flow flow and gas volume fraction measurement mechanism have the measurement pipeline section, in measuring pipeline section, be provided with the vortex generation body of vortex shedding flow meter, have two on meeting measurement pipeline section between stream end face 0.2D～1.0D apart from vortex generation body in the downstream of the vortex generation body of vortex shedding flow meter and be symmetrical in the pressure ports of measuring the pipeline section axis, be symmetrical between the pressure port of measuring the pipeline section axis at two and be connected to differential pressure pick-up by pressure guiding pipe, be connected to signal processing circuit after the differential pressure pick-up, signal processing circuit is: constant-current supply and differential pressure pick-up, programmable amplifier, sef-adapting filter, A/D converter, single-chip microcomputer joins, single-chip microcomputer and programmable amplifier join, and single-chip microcomputer and sef-adapting filter join.

Described programmable amplifier circuit is that amplifier A1 the 8th pin joins through digital regulation resistance U1 and amplifier A1 first pin, amplifier A1 positive input terminal and resistance R 1 are joined, amplifier A1 positive input terminal is through capacitor C 1 ground connection, amplifier A1 negative input end and resistance R 2 are joined, amplifier A1 negative input end is through capacitor C 2 ground connection, and amplifier A1 output terminal is through potentiometer W1, resistance R 3 ground connection.

The sef-adapting filter circuit is that amplifier A2 and amplifier A3, amplifier A4, wave filter U2 join, and the positive input terminal of amplifier A2 meets power supply V through resistance R 3 _DDThe positive input terminal of amplifier A2 is through voltage stabilizing diode D1 ground connection, the output terminal of the negative input end of amplifier A2 and amplifier A2 joins, the output terminal of amplifier A2 connects the negative input end of amplifier A3 through resistance R 4, the output terminal of amplifier A2 is through resistance R 4, resistance R 7 is joined with amplifier A3 output terminal, the positive input terminal of amplifier A3 is through resistance R 6 ground connection, the negative input end connecting resistance R5 of amplifier A3, the output terminal of amplifier A3 connects the negative input end of amplifier A4 through resistance R 8, the output terminal of amplifier A3 is through resistance R 8, resistance R 10 connects the output terminal of amplifier A4, the output terminal of amplifier A3 is through resistance R 8, resistance R 10 connects wave filter U2 input end, the positive input terminal of amplifier A4 is through resistance R 9 ground connection, and the output terminal of amplifier A4 and wave filter U2 input end join.

The distance that pressure port on the measuring tube tube wall and vortex generation body are met the stream end face is 0.2D～1.0D, and D is the interior diameter of vortex shedding flow meter.

The shape of cross section of vortex generation body is trapezoidal, and the fluoran stream surface width of vortex generation body is 0.20～0.33 with the ratio of measuring tube internal diameter.

The utility model has only used a vortex shedding flow meter promptly to realize measuring simultaneously the flow and the gas volume fraction of gas-liquid two-phase bubbly flow, its measurement component movable piece simple in structure, no, with low cost, its signal processing fast, accurately, conveniently can satisfy the requirement of the online detection of industry spot.

Description of drawings

Fig. 1 is a pick-up unit structural representation of the present utility model;

Fig. 2 is a signal processing circuit block diagram of the present utility model;

Fig. 3 is the utility model programmable amplifier circuit diagram;

Fig. 4 is the utility model sef-adapting filter circuit diagram;

Fig. 5 is the utility model pressure port position view;

Fig. 6 is the vortex generation body cross sectional representation of the utility model vortex shedding flow meter;

Fig. 7 is the differential pressure original signal synoptic diagram that records with pick-up unit of the present utility model;

Fig. 8 is the pairing power spectrum synoptic diagram of differential pressure original signal among Fig. 7;

Fig. 9 is differential pressure signal frequency and the potpourri reynolds number Re that records with pick-up unit of the present utility model _DGraph of a relation;

Figure 10 is differential pressure signal amplitude and the potpourri reynolds number Re that records with pick-up unit of the present utility model _DGraph of a relation;

Figure 11 is the biphase gas and liquid flow Strouhal number St that records with pick-up unit of the present utility model _TPWith single-phase flow Strouhal number St _SPRatio and the graph of a relation of gas volume fraction β;

Figure 12 is the biphase gas and liquid flow Strouhal number St that records with pick-up unit of the present utility model _TPWith single-phase flow Strouhal number St _SPRatio and potpourri reynolds number Re _DGraph of a relation;

The flow Q of the liquid that the β value that Figure 13 obtains with the utility model calculates _LWith the actual Q that records _LThe comparison diagram of value.

Embodiment

Gas-liquid two-phase bubbly flow flow and gas volume fraction measuring method: on the measuring tube tube wall in the vortex generation body downstream of vortex shedding flow meter, open two pressure ports that are symmetrical in vortex generation body, connect with differential pressure pick-up by pressure guiding pipe and to measure differential pressure between these 2, signal calculates the flow and the gas volume fraction of gas-liquid two-phase bubbly flow through obtaining the frequency and the amplitude of this differential pressure signal after the signal processing respectively.

Describedly be used to calculate the flow of gas-liquid two-phase bubbly flow and the correlation of gas volume fraction is

Q _TP＝f/K，

$\mathrm{\β}=\frac{{\mathrm{\ρ}}_L-\frac{2A}{C}{\left(\frac{S\·K}{f}\right)}^n}{{\mathrm{\ρ}}_L-{\mathrm{\ρ}}_G},$

C＝19.6β ³-21.0β ²+0.983β+1.28475，

In the formula: Q _TPBe the flow of gas-liquid two-phase bubbly flow, m ³S ^-1F is the differential pressure signal frequency, Hz; K is the instrument coefficient of vortex shedding flow meter, m ^-3β is the gas volume fraction of gas-liquid two-phase bubbly flow, and dimension is 1; ρ _LAnd ρ _GBe respectively the density of fluid to be measured and gas, kgm ^-3A is the differential pressure signal amplitude, Pa; S is the measuring tube cross-sectional area, m ²N and C are correction factor.

As shown in Figure 1, gas-liquid two-phase bubbly flow flow and gas volume fraction measurement mechanism have the pipeline section 1 of measurement, in measuring pipeline section, be provided with the vortex generation body 2 of vortex shedding flow meter, have two on meeting measurement pipeline section 1 between stream end face 0.2D～1.0D apart from vortex generation body in the downstream of the vortex generation body of vortex shedding flow meter and be symmetrical in the pressure ports 3 of measuring the pipeline section axis, be symmetrical between the pressure port of measuring the pipeline section axis at two and be connected to differential pressure pick-up 5, be connected to signal processing circuit 6 after the differential pressure pick-up 5 by pressure guiding pipe 4.

As shown in Figure 2, signal processing circuit 6 is: constant-current supply and differential pressure pick-up, programmable amplifier, sef-adapting filter, A/D converter, single-chip microcomputer join, and single-chip microcomputer and programmable amplifier join, and single-chip microcomputer and sef-adapting filter join.The device model that this patent signal processing adopts is: amplifier A1 adopts AD620, and single-chip microcomputer U1 adopts MSP430, and digital regulation resistance U2 adopts X9312, and wave filter U3 adopts MAX7405, and A/D converter U4 adopts ADS7816.

As shown in Figure 3, programmable amplifier circuit in the signal processing circuit is that amplifier A1 the 8th pin joins through digital regulation resistance U1 and amplifier A1 first pin, amplifier A1 positive input terminal and resistance R 1 are joined, amplifier A1 positive input terminal is through capacitor C 1 ground connection, amplifier A1 negative input end and resistance R 2 are joined, amplifier A1 negative input end is through capacitor C 2 ground connection, and amplifier A1 output terminal is through potentiometer W1, resistance R 3 ground connection.The concrete annexation of amplifier A1 circuit is: amplifier A1 the 8th pin joins through digital regulation resistance U1 and amplifier A1 first pin, amplifier A1 the 3rd pin and resistance R 1 are joined, amplifier A1 the 3rd pin is through capacitor C 1 ground connection, amplifier A1 second pin and resistance R 2 are joined, amplifier A1 second pin is through capacitor C 2 ground connection, amplifier A1 the 7th, four pins meet positive and negative power supply VCC and VEE respectively, and amplifier A1 the 6th pin is through potentiometer W1, resistance R 3 ground connection.

As shown in Figure 4, sef-adapting filter circuit in the signal processing circuit is amplifier A2 and amplifier A3, amplifier A4, wave filter U2 joins, the positive input terminal of amplifier A2 meets power vd D through resistance R 3, the positive input terminal of amplifier A2 is through voltage stabilizing diode D1 ground connection, the output terminal of the negative input end of amplifier A2 and amplifier A2 joins, the output terminal of amplifier A2 connects the negative input end of amplifier A3 through resistance R 4, the output terminal of amplifier A2 is through resistance R 4, resistance R 7 is joined with amplifier A3 output terminal, the positive input terminal of amplifier A3 is through resistance R 6 ground connection, the negative input end connecting resistance R5 of amplifier A3, the output terminal of amplifier A3 connects the negative input end of amplifier A4 through resistance R 8, the output terminal of amplifier A3 is through resistance R 8, resistance R 10 connects the output terminal of amplifier A4, the output terminal of amplifier A3 is through resistance R 8, resistance R 10 connects wave filter U2 input end, the positive input terminal of amplifier A4 is through resistance R 9 ground connection, and the output terminal of amplifier A4 and wave filter U2 input end join.

As shown in Figure 5, the distance that pressure port on the measuring tube tube wall and vortex generation body are met the stream end face is 0.2D～1.0D, and D is the interior diameter of vortex shedding flow meter.

As shown in Figure 6, the shape of cross section of vortex generation body is trapezoidal, and the fluoran stream surface width of vortex generation body is 0.20～0.33 with the ratio of measuring tube internal diameter.

In with the gas-liquid two-phase bubbly flow of empty G﹠W, when gas volume fraction β and potpourri reynolds number Re as flow media _DSatisfy condition: β=0～30%, Re _D=4.6 * 10 ⁴～23.5 * 10 ⁴The time, there is stable Karman vortex street to take place in the pipeline in the vortex generation body wake flow.Wherein gas volume fraction β and potpourri reynolds number Re _DBe defined as follows:

β＝Q _G/(Q _G+Q _L) (1)

Re _D＝v _TPρT _PD/μ _TP (2)

v _TP＝(Q _G+Q _L)/S (3)

ρ _TP＝ρ _Gβ+ρ _L(1-β) (4)

μ _TP＝μ _Gβ+μ _L(1-β) (5)

In the formula: Q _GAnd Q _LBe the flow of gas in the gas-liquid two-phase bubbly flow and liquid, m ³S ^-1ρ _LAnd ρ _GBe respectively the density of fluid to be measured and gas, kgm ^-3S is the measuring tube cross-sectional area, m ²v _TP, ρ _TP, μ _TPBe respectively the mean flow rate (unit: ms of gas-liquid two-phase bubbly flow ^-1), average density (unit: kgm ^-3) and average kinetic viscosity (unit: kgm ^-1S ^-1).

Fig. 7 has provided the differential pressure original signal under this condition.By differential pressure signal being carried out Fast Fourier Transform (FFT) (FFT), can obtain their power spectrum.Fig. 8 provided with Fig. 7 respective conditions under the power spectrum of differential pressure signal.At β=0～30%, Re _D=4.6 * 10 ⁴～23.5 * 10 ⁴In the scope, change the flow of gas and liquid, recorded the differential pressure original signal under the various conditions, and calculated the power spectrum of they correspondences, the frequency of main peak correspondence is the vortex street frequency in the power spectrum, and these results as shown in Figure 9.As can be seen from Figure 9, the vortex street frequency is directly proportional with the potpourri Reynolds number in the gas-liquid two-phase bubbly flow scope of experiment, gets through linear match

f＝2.797Re _D-1.2607(6)

The amplitude that Figure 10 has provided differential pressure signal is when different volumes void fraction β and the potpourri reynolds number Re _DRelation.The differential pressure amplitude A is defined as follows:

$A=\frac{1}{2N}(\underset{i=1}{\overset{N}{\mathrm{\Σ}}}{A}_{\max }^i-\underset{i=1}{\overset{N}{\mathrm{\Σ}}}{A}_{\min }^i)---\left(7\right)$

In the formula: A _Max ⁱAnd A _Min ⁱBe illustrated respectively in differential pressure maximal value and minimum value in i the complete cycle, Pa; N is a complete cycle number in the signal, and dimension is 1.A and two-phase flow hybrid density ρ _TPWith flow velocity v _TPRelation can be expressed as:

$A=\frac{1}{2}{\mathrm{C\ρ}}_{\mathrm{TP}}{v}_{\mathrm{TP}}^n---\left(8\right)$

In the formula: n and C are correction factor.

In vortex shedding flow meter, write out following relational expression between flow and the vortex street frequency usually:

Q＝f/K (9)

Wherein K is called the instrument coefficient of vortex shedding flow meter, is defined as follows:

$K=\frac{4\mathrm{St}}{\mathrm{\&pi;}{\mathrm{<figure-callout\; id="2"\; label="D"\; filenames="Y20062013992600091.png,Y20062013992600101.png"\; state="\{\{state\}\}">D</figure-callout>}}^2\mathrm{md}}---\left(10\right)$

In the formula: St is nondimensional Strouhal number.Use the Strouhal number of the form definable biphase gas and liquid flow of single-phase flow

$S{t}_{\mathrm{TP}}=\frac{\mathrm{fd}}{v_{\mathrm{TP}}}---\left(11\right)$

Biphase gas and liquid flow Strouhal number St according to above definition calculating _TPWith single-phase flow Strouhal number St _SPRatio and gas volume fraction β and potpourri reynolds number Re _DRelation respectively as Figure 11 and shown in Figure 12.As seen Strouhal number is subjected to β and Re in scope of experiment _DInfluence all less, therefore can use St _SPSubstitute St _TPAccording to formula (10), be applicable to that the instrument coefficient of the vortex shedding flow meter of single-phase flow can be used for the measurement of gas-liquid two-phase bubbly flow equally, promptly has

Q _TP＝f/K (12)

As seen, as long as calculate the frequency f that from differential pressure signal, has obtained vortex street, then just can try to achieve the flow of gas-liquid two-phase bubbly flow according to formula (12) by FFT.

Simultaneous formula (3), (4), (8) and (9), put in order:

$\mathrm{\&beta;}=\frac{{\mathrm{\&rho;}}_L-\frac{2A}{C}{\left(\frac{S\&CenterDot;K_{\mathrm{TP}}}{f}\right)}^n}{{\mathrm{\&rho;}}_L-{\mathrm{\&rho;}}_G}---\left(13\right)$

By demarcating, obtain correction factor n=2.3244, correction factor C can calculate with following formula

C＝19.6β ³-21.0β ²+0.983β+1.28475 (14)

Because 0＜β＜0.3 is so simultaneous solution formula (13) and (14) can obtain the β value.The flow Q of the liquid that the β value that obtains with this method calculates _LWith the actual Q that records _LValue more as shown in figure 13, visible in scope of experiment their error all in ± 10%.

In sum, can measure the flow and the gas volume fraction of gas-liquid two-phase bubbly flow as can be known accurately and easily according to the method that the utility model proposes according to above principle.

Claims (5)

1, a kind of gas-liquid two-phase bubbly flow flow and gas volume fraction measurement mechanism, it is characterized in that: it has measuring tube (1), in measuring pipeline section, be provided with the vortex generation body (2) of vortex shedding flow meter, meet apart from vortex generation body in the downstream of the vortex generation body of vortex shedding flow meter on the measuring tube (1) of stream end face 0.2D～1.0D and have two pressure ports (3) that are symmetrical in the measuring tube axis, between two pressure ports that are symmetrical in the measuring tube axis, be connected to differential pressure pick-up (5) by pressure guiding pipe (4), differential pressure pick-up (5) joins with signal processing circuit (6), signal processing circuit (6) is: constant-current supply and differential pressure pick-up, programmable amplifier, sef-adapting filter, A/D converter, single-chip microcomputer joins, single-chip microcomputer and programmable amplifier join, and single-chip microcomputer and sef-adapting filter join.

2, a kind of gas-liquid two-phase bubbly flow flow according to claim 1 and gas volume fraction measurement mechanism, it is characterized in that: described programmable amplifier circuit is: amplifier A1 the 8th pin joins through digital regulation resistance U1 and amplifier A1 first pin, amplifier A1 positive input terminal and resistance R 1 are joined, amplifier A1 positive input terminal is through capacitor C 1 ground connection, amplifier A1 negative input end and resistance R 2 are joined, amplifier A1 negative input end is through capacitor C 2 ground connection, and amplifier A1 output terminal is through potentiometer W1, resistance R 3 ground connection.

3, a kind of gas-liquid two-phase bubbly flow flow according to claim 1 and gas volume fraction measurement mechanism, it is characterized in that: described sef-adapting filter circuit is that amplifier A2 and amplifier A3, amplifier A4, wave filter U2 join, and the positive input terminal of amplifier A2 meets power supply V through resistance R 3 _DDThe positive input terminal of amplifier A2 is through voltage stabilizing diode D1 ground connection, the output terminal of the negative input end of amplifier A2 and amplifier A2 joins, the output terminal of amplifier A2 connects the negative input end of amplifier A3 through resistance R 4, the output terminal of amplifier A2 is through resistance R 4, resistance R 7 is joined with amplifier A3 output terminal, the positive input terminal of amplifier A3 is through resistance R 6 ground connection, the negative input end connecting resistance R5 of amplifier A3, the output terminal of amplifier A3 connects the negative input end of amplifier A4 through resistance R 8, the output terminal of amplifier A3 is through resistance R 8, resistance R 10 connects the output terminal of amplifier A4, the output terminal of amplifier A3 is through resistance R 8, resistance R 10 connects wave filter U2 input end, the positive input terminal of amplifier A4 is through resistance R 9 ground connection, and the output terminal of amplifier A4 and wave filter U2 input end join.

4, a kind of gas-liquid two-phase bubbly flow flow according to claim 1 and gas volume fraction measurement mechanism, it is characterized in that: the pressure port (3) on described measuring tube (1) tube wall is 0.2D～1.0D with the distance that vortex generation body (2) is met the stream end face, and D is the interior diameter of vortex shedding flow meter.

5, a kind of gas-liquid two-phase bubbly flow flow according to claim 1 and gas volume fraction measurement mechanism, it is characterized in that: the shape of cross section of described vortex generation body (2) is trapezoidal, and the ratio of the fluoran stream surface width of vortex generation body (2) and measuring tube (1) internal diameter is 0.20～0.33.

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