CN1063361A - Capacitance-type two-phase flowing observance concentration meter and measuring method thereof - Google Patents
Capacitance-type two-phase flowing observance concentration meter and measuring method thereof Download PDFInfo
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- CN1063361A CN1063361A CN 91100073 CN91100073A CN1063361A CN 1063361 A CN1063361 A CN 1063361A CN 91100073 CN91100073 CN 91100073 CN 91100073 A CN91100073 A CN 91100073A CN 1063361 A CN1063361 A CN 1063361A
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Abstract
A kind of capacitance-type two-phase flowing observance concentration meter and measuring method thereof belong to a kind of industrial detection instrument and measuring method.The phase concentration measurement is the important topic that is run in two-phase flow industrial detection and the laboratory study.Existing instrument and method are bigger because of being subjected to flow pattern to influence measuring error.The present invention has released a kind of convection and has changed insensitive phase concentration and take into account measuring method, it is characterized in that adopting the multielectrode capacitance sensor of ring texture, by optimizing the electrode structure size, on the liquid-filled pipe xsect, cause and measure sensitivity profile everywhere uniformly, put the wheel measuring of realizing again around the pipeline axle center before this, the measured value on the different rotary angle is averaged as the phase concentration signal.The present invention combines uniform field and rotation field method, has reduced the influence of flow pattern greatly.
Description
The invention belongs to a kind of two-phase fluid measuring instrument and measuring method thereof.
The two-phase flow phase-concentration measurement is the important topic that is run in two-phase flow commercial measurement and the laboratory study.It is low to adopt the capacitance measurement phase concentration to have a cost, the reliability height, and therefore noncontact and can measure advantage such as whole liquid-filled pipe cross section is subjected to relevant researchist's attention both at home and abroad.Yet adopt the greatest problem of capacitance method to be, the output that state that two-phase distributes in the pipeline or flow pattern influence capacitive transducer causes very big measuring error.For addressing this problem, someone has proposed the method that adopts rotating electric field to measure, measure the method that electricity is led as the rotating electric field of utilizing that people such as M.Merilo propose in " Void fraotion measurement with a rotating eleotrio field conduotanoe gauge " (J.Heat Transfer P330 1977) literary composition, by three-phase alternating voltage being added in respectively on three pairs of electrodes of conduit arrangements, cause the rotation of measuring electric field, thereby eliminated the influence of the directivity at the interface that distributes mutually to a great extent, reduced the influence of flow pattern.Responsive that the electrode structure that the shortcoming of said method is to be adopted is produced on pipeline section is not uniform everywhere.Susceptibility is higher near the zone of electrode, and lower at the susceptibility in pipeline center zone.Way by rotating electric field can not overcome this shortcoming.Consequent result is that the influence of flow pattern can not further reduce, and especially the measurement result for ring-type and these two kinds of rotational symmetry flow patterns of column differs greatly each other.
Another kind method is that people such as C.C.Xie is at " Design of oapacitanoe eleotrodes for conoentration measurement of two-phase flow " (Meas.Sci Technol.1(1990) 65-78) the even responsive method described in the literary composition, promptly constitute capacitive transducers, can obtain the uniform susceptibility distribution of almost everywhere on pipeline section by the parameters such as subtended angle of suitable selection insulation tube wall thickness and electrode pair die at two arc-shaped electrodes of the peripheral arrangement of one section isolated pipe.This method effect when measurement axis symmetric distributed flow pattern is better, but for the distribution of non-axisymmetric, very responsive as the phase interface orientation of various laminar flow, the measuring error of bringing thus is very big.Though as seen responsive of this method generation evenly but has fixing directivity.
Therefore, above-mentioned two kinds of methods all can not solve the problem of flow pattern influence satisfactorily.
The object of the present invention is to provide and a kind ofly be not subjected to distribute mutually or flow pattern influences and only the condenser type phase concentration of phase concentration sensitivity taken into account measuring method.
According to the present invention, condenser type two-phase flow densimeter is made up of two pairs or more electrode and signal Processing and the control circuit of settling on the liquid-filled pipe of insulation, it is characterized in that having taked following measure:
(1) distance [R in the inside surface of electrode [1～10] and liquid-filled pipe [11] axle center
2] and liquid-filled pipe inside radius [R1] between should satisfy formula
3R
1≥R
2≥1.5R
1
(2) select above-mentioned one first pole plate to several electrodes composition measured capacitance, select same number of electrode to form second pole plate at the opposite side of liquid-filled pipe on about the position of pipeline axle center symmetry, the angle [θ] that above-mentioned first and second pole plate are opened the pipeline axle center is 70 °～130 °, will not be selected into the electrode grounding of above-mentioned two pole plates.
Above-mentioned electrode is meant and is placed in the liquid-filled pipe periphery, the equidistant circlewise arcuation electrode of arranging.
Above-mentioned pole plate is to adopt electronic switch [31～35] to select electrode to form.
The electrode structure of above-mentioned capacitance-type two-phase flowing observance concentration meter is characterized in that insulating pipe for settling electrode in the peripheral installation one of liquid-filled pipe, makes the electrode of annular array and liquid-filled pipe form concentric structure, to satisfy formula
3R
1≥R
2≥1.5R
1
The electrode structure of above-mentioned capacitance-type two-phase flowing observance concentration meter, the pipe thickness that it is characterized in that thickening liquid-filled pipe is to satisfy formula
3R
1≥R
2≥1.5R
1
According to capacitance-type two-phase flowing observance concentration meter, we propose a kind of condenser type two-phase flow phase-concentration measuring method simultaneously, it is characterized in that using above-mentioned capacitance-type two-phase flowing observance concentration meter, by switching the annexation of excitation power supply and metering circuit and above-mentioned each electrode, the position of first and second pole plate of above-mentioned measured capacitance is rotated around the pipeline axle center, the mean value of the measurement capacitance of obtaining on all different rotary positions through signal processing circuit is obtained, as the phase concentration output signal.
Characteristics of the present invention are by selecting the optimized electrode structure size, on the liquid-filled pipe xsect, cause one to measure responsive everywhere uniformly, put the wheel measuring of realizing responsive field again before this, uniform field and rotation field measuring method advantages are separately got up, overcome its deficiency separately.Preliminary experiment is the result show, when measuring phase concentration with method provided by the invention under various different flow patterns, the gained error is significantly less than the measuring error of prior art, thereby has proved effect of the present invention.
Be a concrete scheme of the present invention below, be illustrated by means of following accompanying drawing:
Fig. 1 is the system principle diagram of above-mentioned concrete enforcement.
Fig. 2 is the mounting structure of sensor electrode.
Fig. 3 is the measuring system circuit theory diagrams.
Fig. 4 is the table that is connected of switch and control signal among Fig. 3.
Fig. 5 is the state of a control sequence list of switch among Fig. 3.
A concrete principle of implementing of the present invention as shown in Figure 1, its Sensor section is installed insulation pipeline section [12] etc. by electrode [1～10], current-carrying insulation pipeline section [11], electrode and is formed.The selection of two measured capacitance pole plates of semiconductor switch array [13] control and position rotation thereof.Electric capacity between two-plate is relevant with phase concentration.Electric capacity/electric pressure converter [14] is converted to voltage signal with two selected interelectrode capacitances.Become the binary digit amount to send into microprocessor system [16] this voltage transitions with an A/D converter [15].The periodic duty of microprocessor [16] gauge tap array [13] and A/D converter [15], and the measurement capacitance on all position of rotation in each cycle is averaged, the phase concentration signal obtained.
Adopt the electrode mounting structure shown in Fig. 2 a and Fig. 2 b and pass through suitably to select radius ratio R
2/ R
1And central angle θ, can obtain responsive uniformly field on liquid-filled pipe [11] cross section everywhere.Select R in the present embodiment
2/ R
1≈ 2.2,108 ° of θ ≈.Wherein to be about 108 ° be owing to select 3 electrodes to be connected together to constitute a measured capacitance pole plate at every turn in above-mentioned 10 electrode systems to θ angle value.In order to prevent the interference of ambient electromagnetic field, the whole sensor part is shielded by metal housing [17].10 contact conductors adopt coaxial shielding cable [18～27].The pipeline [12] of battery lead plate is housed, is installed on the liquid-filled pipe [11] by metal support [28] [29].
The concrete course of work of measuring system shown in Figure 1 can be illustrated in conjunction with Fig. 4 and Fig. 5 by Fig. 3.
When begin a measuring period, microprocessor system [16] is given parallel register [63] with sexadecimal status word 01, make control signal [64] be high level, all the other are zero, measured capacitance is in position of rotation 1, this moment switch [31] [34] [36] [39] [41] [44] [46] [49] [50] [52] closure, all the other disconnections, make electrode [1] [2] [3] meet ac voltage signal S simultaneously, become the pole plate of measured capacitance, [6] [7] [8] meet the input end D of capacitive feedback formula current detector [69], become another pole plate of measured capacitance.Electrode [4] [5] [9] [10] is as idle electrode grounding.The transformer alternating electric bridge that electric capacity between the measured capacitance two-plate is made up of transformer [54], reference capacitance [55], audible communication power supply [70] and current detector [69] is measured.Be about to measured capacitance and be connected between S and the D end, as a brachium pontis, compare with reference capacitance [55] on another brachium pontis, the out-of-balance current of the transformer alternating electric bridge being exported with current detector [69] converts ac voltage signal to.This measuring method only with two tested plates between electric capacity relevant, and insensitive to tested plates and lead-in wire distributed capacitance over the ground thereof.Reference capacitance [55] is used for the balance bridge circuit, and when making discrete phase concentration in the liquid-filled pipe be zero, the output of electric capacity/electric pressure converter [14] also is approximately zero.Current detector [69] is made up of broadband operational amplifier [56], feedback capacity [57], resistance [58], wherein feedback capacity [57] determines the ac gain of detecting device, resistance [58] is generally 100M Ω, is used to provide DC feedback and prevents that the direct current of operational amplifier [56] is saturated.Ac voltage signal by current detector [69] output, through bandpass filter [59], AC amplifier [60] is converted to d. c. voltage signal after phase-sensitive demodulator [61] and the low-pass filter links such as [62], is converted to digital signal through A/D converter [15] again and deposits microprocessor system [16] in.
After said process was finished, microprocessor [16] was changed to high level with control signal [65], and all the other control signals are zero level.Measured capacitance is in position of rotation 2.According to form among switch arrangement among Fig. 3 and Fig. 4 as can be known, electrode [2] [3] [4] is logical with the S termination, and [7] [8] [9] are logical with the D termination, form two tested plates respectively, and electrode [5] [6] [10] [1] is as idle electrode grounding.After system finishes electric capacity/voltage transitions, A/D conversion and signal storage, begin again to rotate on the 3rd position.The rest may be inferred, and on the 5th position of rotation, the mode control word in the register is 10, and [68] are high level in the control signal end, and all the other are low.According to the form among Fig. 4 as can be known, electrode [5] [6] [7] connects the S end, and [10] [1] [2] connects the D end, forms two pole plates of measured capacitance, and [3] [4] [8] [9] ground connection.Measure and after data-storing finished, microprocessor [16] was averaged 5 measured values, exports as the phase concentration value in the 5th.So far finished a wheel measuring cycle.When next cycle began, microprocessor [16] sent register with control word 01 again, repeated said process.
According to the static experimental result of being done on the experimental prototype of system as shown in Figure 3, method provided by the present invention is reducing aspect the variations in flow patterns influence, and effect is fairly obvious.Compare with the uniform-field method of external employing, this law is when measuring various laminar flow with different distributions direction, and viewed maximum error is 5%, and is about 25% with uniform field method maximum error of measuring under similarity condition.Therefore proved the superiority of this law.Owing to do not adopt the optimum electrode parameter in above-mentioned experiment, therefore if further optimize electrode structure, error can also reduce.
Claims (6)
1, capacitance-type two-phase flowing observance concentration meter is made up of two pairs or more electrode and signal Processing and the control circuit of settling on the liquid-filled pipe of insulation, it is characterized in that having taked following measure:
(1) inside surface of electrode [1～10] is to the distance [R in liquid-filled pipe [11] axle center
2] and liquid-filled pipe inside radius [R
1] between should satisfy formula
3R
1≥R
2≥1.5R
1
(2) select above-mentioned one first pole plate to several electrodes composition measured capacitance, select same number of electrode to form second pole plate at the opposite side of liquid-filled pipe on about the position of pipeline axle center symmetry, the angle [θ] that above-mentioned first and second pole plate are opened the pipeline axle center is 70 °～130 °, will not be selected into the electrode grounding of above-mentioned two pole plates.
2, electrode according to claim 1 is meant to be placed in the liquid-filled pipe periphery, circlewise the arcuation electrode of equidistantly arranging.
3, pole plate according to claim 1 is to adopt electronic switch [31～53] to select electrode to form.
4, according to claim 1,2 described electrode structures is characterized in that the peripheral insulation pipe of installing of liquid-filled pipe for settling electrode, makes the electrode of annular array and liquid-filled pipe form concentric structure, to satisfy formula
3R
1≥2R
2≥1.5R
1
5, according to claim 1,2 described electrode structures, the pipe thickness that it is characterized in that thickening liquid-filled pipe is to satisfy formula
3R
1≥R
2≥1.5R
1
6, a kind of condenser type two-phase flow phase-concentration measuring method, it is characterized in that using the described capacitance-type two-phase flowing observance concentration meter of claim 1, by switching the annexation of each electrode described in excitation power supply and metering circuit and the claim 1, the position of first and second pole plates of the measured capacitance described in the claim 1 is rotated around the pipeline axle center, the mean value of the measurement capacitance that will obtain on all different rotary positions through signal processing circuit is obtained, as the output signal of phase concentration.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 91100073 CN1063361A (en) | 1991-01-11 | 1991-01-11 | Capacitance-type two-phase flowing observance concentration meter and measuring method thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 91100073 CN1063361A (en) | 1991-01-11 | 1991-01-11 | Capacitance-type two-phase flowing observance concentration meter and measuring method thereof |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN1063361A true CN1063361A (en) | 1992-08-05 |
Family
ID=4904433
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 91100073 Pending CN1063361A (en) | 1991-01-11 | 1991-01-11 | Capacitance-type two-phase flowing observance concentration meter and measuring method thereof |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101324186B (en) * | 2008-07-04 | 2012-05-23 | 西安交通大学 | Device for measuring oil, gas, water three phase flow containing rate |
| CN102997834A (en) * | 2012-12-12 | 2013-03-27 | 山东建筑大学 | Non-conducting medium film thickness online detecting device of coplane capacitive sensor |
| CN107388700A (en) * | 2017-01-20 | 2017-11-24 | 芯海科技（深圳）股份有限公司 | A kind of refrigerator coagulates white sensor |
| CN108845002A (en) * | 2018-06-28 | 2018-11-20 | 长安大学 | A kind of methanol gasoline concentration detection apparatus and method |
| CN113125515A (en) * | 2021-04-14 | 2021-07-16 | 东北石油大学 | Water holding capacity conductivity measurement method of oil-water two-phase flow without influence of mineralization degree |
-
1991
- 1991-01-11 CN CN 91100073 patent/CN1063361A/en active Pending
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101324186B (en) * | 2008-07-04 | 2012-05-23 | 西安交通大学 | Device for measuring oil, gas, water three phase flow containing rate |
| CN102997834A (en) * | 2012-12-12 | 2013-03-27 | 山东建筑大学 | Non-conducting medium film thickness online detecting device of coplane capacitive sensor |
| CN107388700A (en) * | 2017-01-20 | 2017-11-24 | 芯海科技（深圳）股份有限公司 | A kind of refrigerator coagulates white sensor |
| CN108845002A (en) * | 2018-06-28 | 2018-11-20 | 长安大学 | A kind of methanol gasoline concentration detection apparatus and method |
| CN113125515A (en) * | 2021-04-14 | 2021-07-16 | 东北石油大学 | Water holding capacity conductivity measurement method of oil-water two-phase flow without influence of mineralization degree |
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