CN105510626A - Electromagnetic measurement device and method capable of monitoring flowing speed of fluid for long time - Google Patents
Electromagnetic measurement device and method capable of monitoring flowing speed of fluid for long time Download PDFInfo
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- CN105510626A CN105510626A CN201510744388.0A CN201510744388A CN105510626A CN 105510626 A CN105510626 A CN 105510626A CN 201510744388 A CN201510744388 A CN 201510744388A CN 105510626 A CN105510626 A CN 105510626A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
- G01P5/00—Measuring speed of fluids, e.g. of air stream; Measuring speed of bodies relative to fluids, e.g. of ship, of aircraft
- G01P5/18—Measuring speed of fluids, e.g. of air stream; Measuring speed of bodies relative to fluids, e.g. of ship, of aircraft by measuring the time taken to traverse a fixed distance
Abstract
The invention discloses an electromagnetic measurement device and method capable of monitoring the flowing speed of fluid for a long time. An electromagnetic method is used for measuring gas-liquid two-phase flowing speeds, and the principle is that gas in the two-phase flow will enable the phase of a mutual inductance signal to change while passing a sensor, and the synchronization data collection is carried out on two measurement cross sections which are separated at a certain distance. Meanwhile, the same feature points in two groups of data are extracted, and the time of bubbles in passing the two cross sections can be obtained, thereby calculating the mean flowing speed in the time. When the spacing between the measurement cross section is small enough, the approximate instantaneous flow speed of the fluid can be obtained. The device and method can achieve the quick and accurate measurement of the flowing speed of the measured fluid, and meet the demands of long-time monitoring of the gas-liquid two-phase flowing speeds in an industrial process. The whole measurement process is convenient and flexible, and is accurate and reliable. Compared with a conventional measurement method, the method is remarkable in effect and advantages.
Description
Technical field
The invention belongs to the fluid-velocity survey field for low conductivity fluid, relate to a kind of electromagnetic measurement device and the measuring method that can be used for long term monitoring rate of flow of fluid.
Background technology
Biphase gas and liquid flow is ubiquity in the industrial processs such as nature and chemical industry, pharmacy, oil, and the monitoring of its discrete phase speed is a very important research topic.Existing rate of flow of fluid measuring method mainly contains measurement method of electricity, optical measuring method and High Speed Photography, in wherein electrical measurement scheme, detection part is many directly contacts with detected fluid, easily cause the problems such as galvanic corrosion, be not suitable for and carry out long term monitoring in commercial Application, also usually occur motor pickup in the application scenario that measurement environment is poor, these all can have a strong impact on accuracy and the practical of measurement result simultaneously; And optical method and High Speed Photography are often higher to the requirement of applied environment, also there is the higher problem of cost simultaneously, be difficult to obtain large-scale application in actual industrial environment.
Summary of the invention
(1) goal of the invention
The object of this invention is to provide a kind of electromagnetic measurement device and the measuring method that can be used for long term monitoring rate of flow of fluid, realize utilizing the undesirable mutual electromagnetic inductance information between coaxial coil to measure rate of flow of fluid fast and accurately.
(2) technical scheme
In order to solve the problems of the technologies described above, the invention provides a kind of electromagnetic measurement device that can be used for long term monitoring rate of flow of fluid, it comprises: comprise PC main frame, connect the FPGA mainboard of PC main frame, and connect the sensor of FPGA mainboard, FPGA mainboard comprises the microprocessor being connected PC main frame by USB interface, and the Direct Digital Frequency Synthesizers of connection microprocessor, analog/digital conversion module, D/A switch module and totalizer, Direct Digital Frequency Synthesizers connects analog/digital conversion module, D/A switch model calling totalizer; Sensor comprises coaxial drive coil and receiving coil, and front-end circuit, front-end circuit comprises the power amplifier module connecting analog/digital conversion module, the signal pre-processing module connecting D/A switch module, and connect the analog switch of drive coil, receiving coil, power amplifier module and signal pre-processing module, described microprocessor is also connected with analog switch, logic control signal is transmitted, with the break-make of control simulation switch to analog switch.
Wherein, when described measurement mechanism is used for rate of flow of fluid measurement, drive coil and receiving coil are arranged on detected fluid pipeline external surface and correspondence one measures cross section respectively, and two distances measured between cross sections are fixed as a preset value, sensor surrounding parcel shielding material.
Present invention also offers a kind of method for electromagnetically measuring that can be used for long term monitoring rate of flow of fluid, when measuring rate of flow of fluid, drive coil injects the pumping signal of predeterminated frequency and amplitude, according to electromagnetic induction principle, corresponding receiving coil produces the induced voltage identical with exciting signal frequency; After induced signal is transferred to FPGA mainboard by front-end circuit, digital signal is changed into through AD sampling, data are carried out collection and are stored by FPGA mainboard, demodulating algorithm is adopted to obtain the phase information of induced signal, synchronous data collection is carried out in two measurement cross sections of predeterminable range, extract the time that unique point identical in two groups of data uses through two cross sections to obtain bubble, calculate the mean flow rate of this period, when the spacing that two are measured cross section is infinitely small, obtain the instantaneous velocity of fluid.
Wherein, the predeterminated frequency of described pumping signal is fixing frequency point value or frequency band, when the predeterminated frequency of pumping signal is fixing frequency point value, two distances measured between cross section are utilized to obtain the mean flow rate of fluid within this period divided by bubble through the time that two cross sections use; When the predeterminated frequency of pumping signal is frequency band, adopt the method for sweep measurement, excitation frequency and frequency sweep point are set by PC main frame by operating personnel in advance, use the pumping signal of this frequency band during measurement successively, average after obtaining tasselled measurement result corresponding to each Frequency point.
Wherein, described demodulating algorithm adopts quadrature demodulation method.
(3) beneficial effect
Electromagnetic measurement device and the measuring method of what technique scheme provided can be used for long term monitoring rate of flow of fluid, quick, the Measurement accuracy to detected fluid flow velocity can be realized, sensor design had both met measurement requirement, the problems such as touch sensor corrosion-vulnerable can be avoided again, more be applicable to meeting the demand of in industrial process, biphase gas and liquid flow flow velocity being carried out to long term monitoring; By taking the method such as sweep measurement, noise shielding, make whole measuring process convenient, flexible, accurately and reliably, have obvious effect and advantage compared with traditional measuring method.
Accompanying drawing explanation
Fig. 1 is the invention process ratio sensor schematic diagram;
Fig. 2 is embodiment of the present invention measurement mechanism functional block diagram;
Fig. 3 is embodiment of the present invention flow regime map;
Fig. 4 is embodiment of the present invention data acquisition curve;
Fig. 5 is embodiment of the present invention upper computer software interface schematic diagram.
Embodiment
For making object of the present invention, content and advantage clearly, below in conjunction with drawings and Examples, the specific embodiment of the present invention is described in further detail.
For problems of the prior art, the present embodiment attempts measurement application electromagnetic measurement method being incorporated into two-phase flow speed, the advantage that this method is maximum be non-contact measurement, measuring equipment without the need to directly contacting measurand, overcome conventional contact measure some main shortcomings, affected by environment little, long service life, rely on High-frequency electromagnetic data acquisition system, measuring speed is fast, measuring accuracy is high etc., and structure is simple simultaneously, cost is lower.Electromagnetic Testing Technology is based on EDDY CURRENT, and its ultimate principle can be expressed as: when the test coil being loaded with exchange current is near testee, and the effect of the alternating magnetic field produced due to coil can generate eddy current in object.The size of eddy current, phase place and liquid form are subject to the impact of target sizes, shape and electrology characteristic thereof, and the retroaction of eddy current makes the mutual inductance between coil change.The electrology characteristic of testee determines the sensitivity amount of electric measurement method, utilize electromagnetic method measure high conductivity object time (as metallic conductor), because the eddy current produced is stronger, testee is just as mirror, the electromagnetic signal of a part is reflected back, cause the reduction of receiving sensor induced signal, be embodied in the reduction of amplitude; And when testee conductivity lower (as salt solution), the eddy current wherein produced is very weak, most electromagnetic signal is through testee, and the induced signal therefore on receiving sensor changes in amplitude and not quite, its change is mainly manifested in phase place.Electromagnetic method is utilized to measure biphase gas and liquid flow flow velocity, principle is exactly that gas phase-splitting in two-phase flow can make the phase place of mutual inductance signal change through sensor, synchronous data collection is being carried out apart from certain two measurement cross sections, extract unique point identical in two groups of data and can obtain the time that bubble uses through two cross sections, thus calculate the mean flow rate of this period, when two are measured enough hour of the spacing in cross sections, the approximate instantaneous velocity of fluid just can be obtained.
As shown in Figure 1, the important component part sensor of the present embodiment is made up of two pairs of coaxial coils and front-end circuit, and cross section measured by often pair of corresponding one of coil, and two distances measured between cross section are fixed as d.Sensor surrounding parcel shielding material, measuring process coil is arranged on fluid line outside surface, both measurement demand can be met, the direct contact between survey sensor and tested electrolyte can be avoided again, the sensor etching problem preventing Long contact time from causing, increase the service life, ensure measuring accuracy.
As shown in Figure 2, the present embodiment measurement mechanism comprises PC main frame, connect the FPGA mainboard of PC main frame, and connect the sensor of FPGA mainboard, FPGA mainboard comprises the microprocessor being connected PC main frame by USB interface, and the Direct Digital Frequency Synthesizers of connection microprocessor, analog/digital conversion module, D/A switch module and totalizer, Direct Digital Frequency Synthesizers connects analog/digital conversion module, D/A switch model calling totalizer; Sensor comprises coaxial drive coil and receiving coil, and front-end circuit, front-end circuit comprises the power amplifier module connecting analog/digital conversion module, the signal pre-processing module connecting D/A switch module, and connect the analog switch of drive coil, receiving coil, power amplifier module and signal pre-processing module, described microprocessor is also connected with analog switch, logic control signal is transmitted, with the break-make of control simulation switch to analog switch.
During measurement, injected frequency and the certain sinusoidal ac signal of amplitude on drive coil, according to electromagnetic induction principle, corresponding receiving coil can produce the induced voltage identical with exciting signal frequency.After induced signal is transferred to electromagnetic detection, digital signal is changed into through AD sampling, data are carried out collection and are stored by FPGA, the phase information of induced signal is obtained by certain demodulating algorithm, synchronous data collection is being carried out apart from certain two measurement cross sections, extract unique point identical in two groups of data and can obtain the time that bubble uses through two cross sections, thus calculate the mean flow rate of this period, when two are measured enough hour of the spacing in cross sections, the approximate instantaneous velocity of fluid just can be obtained.
At present relatively more conventional demodulating algorithm is quadrature demodulation method, and this algorithm can be regarded as FFT demodulation simplification mathematically, which overcomes the instability of the intrinsic error of mimic channel and system, meets high-performance required by signal analysis and Quick Measurement etc.Excitation frequency is designed to adjustable frequency, frequency range is 1KHz-20MHz, in addition, in order to ensure measuring accuracy, system can also carry out sweep measurement, use the pumping signal of certain frequency section when namely measuring successively, average after obtaining the measurement result of each Frequency point, wherein excitation frequency and frequency sweep point all can be arranged by upper computer software by operating personnel.
The biphase gas and liquid flow environment that exists in the industry is generally divided into horizontal tube and vertical tube, and each self-contained flow structure as shown in Figure 3.The present embodiment is according to physical condition, and the slug flow (slug flow) in selection vertical tube is as measuring object.Sensor fore-and-aft distance is set to 200mm, preserves one group of phase demodulating data every 1ms.Can obtain by measurement of comparison data characteristics point the time that bubble experiences between two cross sections, and then calculate flow velocity.For increasing the comparative of result, in measuring process, biphase gas and liquid flow is set to three kinds of flow velocitys, and data retention over time is 5 seconds (namely preserving 5000 groups of data), and measurement result as shown in Figure 4, for ease of observing, we have carried out longitudinal translation process to data.Can find out, the time tpass no matter experienced by single cross-section sensor from bubble, or from the time that bubble experiences between two cross sections, three kinds of flow velocitys can be gone out clearly respectively.Carry out analyzing and processing to measurement data, flow relocity calculation the results are shown in Table one, wherein maximum point (on) and maximum point (little) represent the sampling number at upper and lower two-layer cross-section sensor induced signal phase angle information segmentation maximum value place respectively.
Measurement result tested by table one
| Fast | Middling speed | At a slow speed | |
| Maximum point (on) | 4613 | 3074 | 2662 |
| Maximum point (under) | 4300 | 2588 | 2144 3 --> |
| Spaced points | 313 | 486 | 518 |
| Interval time | 313ms | 486ms | 518ms |
| Flow velocity | 0.639m/s | 0.412m/s | 0.386m/s |
Fig. 5 is upper computer software interface schematic diagram.This software carries out data interaction by USB and equipment, and operating personnel can also arrange correlation parameter by UI interface, and as selected single incentive mode or frequency sweep mode, the phase curve in two cross sections and measurement result all can directly show.
In sum, the present invention can realize quick, Measurement accuracy to detected fluid flow velocity, sensor design had both met measurement requirement, can avoid the problems such as touch sensor corrosion-vulnerable again, more be applicable to meeting the demand of in industrial process, biphase gas and liquid flow flow velocity being carried out to long term monitoring; By taking the method such as sweep measurement, noise shielding, make whole measuring process convenient, flexible, accurately and reliably, have obvious effect and advantage compared with traditional measuring method.
The above is only the preferred embodiment of the present invention; it should be pointed out that for those skilled in the art, under the prerequisite not departing from the technology of the present invention principle; can also make some improvement and distortion, these improve and distortion also should be considered as protection scope of the present invention.
Claims (5)
1. one kind can be used for the electromagnetic measurement device of long term monitoring rate of flow of fluid, it is characterized in that, comprise: comprise PC main frame, connect the FPGA mainboard of PC main frame, and connecting the sensor of FPGA mainboard, FPGA mainboard comprises the microprocessor being connected PC main frame by USB interface, and the Direct Digital Frequency Synthesizers of connection microprocessor, analog/digital conversion module, D/A switch module and totalizer, Direct Digital Frequency Synthesizers connects analog/digital conversion module, D/A switch model calling totalizer; Sensor comprises coaxial drive coil and receiving coil, and front-end circuit, front-end circuit comprises the power amplifier module connecting analog/digital conversion module, the signal pre-processing module connecting D/A switch module, and connect the analog switch of drive coil, receiving coil, power amplifier module and signal pre-processing module, described microprocessor is also connected with analog switch, logic control signal is transmitted, with the break-make of control simulation switch to analog switch.
2. can be used for the electromagnetic measurement device of long term monitoring rate of flow of fluid as claimed in claim 1, it is characterized in that, when described measurement mechanism is used for rate of flow of fluid measurement, drive coil and receiving coil are arranged on detected fluid pipeline external surface and correspondence one measures cross section respectively, two distances measured between cross section are fixed as a preset value, sensor surrounding parcel shielding material.
3. one kind can be used for the method for electromagnetically measuring of long term monitoring rate of flow of fluid, it is characterized in that, when measuring rate of flow of fluid, drive coil injects the pumping signal of predeterminated frequency and amplitude, according to electromagnetic induction principle, corresponding receiving coil produces the induced voltage identical with exciting signal frequency; After induced signal is transferred to FPGA mainboard by front-end circuit, digital signal is changed into through AD sampling, data are carried out collection and are stored by FPGA mainboard, demodulating algorithm is adopted to obtain the phase information of induced signal, synchronous data collection is carried out in two measurement cross sections of predeterminable range, extract the time that unique point identical in two groups of data uses through two cross sections to obtain bubble, calculate the mean flow rate of this period, when the spacing that two are measured cross section is infinitely small, obtain the instantaneous velocity of fluid.
4. can be used for the method for electromagnetically measuring of long term monitoring rate of flow of fluid as claimed in claim 3, it is characterized in that, the predeterminated frequency of described pumping signal is fixing frequency point value or frequency band, when the predeterminated frequency of pumping signal is fixing frequency point value, two distances measured between cross section are utilized to obtain the mean flow rate of fluid within this period divided by bubble through the time that two cross sections use; When the predeterminated frequency of pumping signal is frequency band, adopt the method for sweep measurement, excitation frequency and frequency sweep point are set by PC main frame by operating personnel in advance, use the pumping signal of this frequency band during measurement successively, average after obtaining tasselled measurement result corresponding to each Frequency point.
5. can be used for the method for electromagnetically measuring of long term monitoring rate of flow of fluid as claimed in claim 3, it is characterized in that, described demodulating algorithm adopts quadrature demodulation method.
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN106771341A (en) * | 2016-12-13 | 2017-05-31 | 中国地质大学（武汉） | Flow sensor, flow rate and direction determine device and method |
| CN107367543A (en) * | 2017-07-17 | 2017-11-21 | 曲阜师范大学 | Bubble measurement apparatus in molten metal based on spiral electromagnetic sensor |
| CN109839160A (en) * | 2019-03-18 | 2019-06-04 | 苏州极目机器人科技有限公司 | Flow detection device, flow rate testing methods and spray appliance |
| CN110441547A (en) * | 2019-09-04 | 2019-11-12 | 中国电建集团中南勘测设计研究院有限公司 | A kind of flow rate of water flow measurement method |
| CN111366745A (en) * | 2020-04-30 | 2020-07-03 | 上海旭润医学科技有限责任公司 | Method for detecting extremely micro flow velocity based on computer image recognition principle |
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| CN104777196A (en) * | 2014-12-03 | 2015-07-15 | 中国航天科工集团第三研究院第八三五七研究所 | Device for real-time measurement of fluid conductivity by use of electromagnetic method |
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| US20070044572A1 (en) * | 2005-07-13 | 2007-03-01 | Michael Davis | Method and apparatus for measuring parameters of a fluid flow using an array of sensors |
| CN101566639A (en) * | 2009-06-05 | 2009-10-28 | 天津大学 | Molten steel flow-speed measurement method and device based on electromagnetic tomography |
| CN103439528A (en) * | 2013-09-16 | 2013-12-11 | 中国矿业大学(北京) | Method and device for measuring flow speed of dense paste based on electromagnetic signal cross correlation |
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN106771341A (en) * | 2016-12-13 | 2017-05-31 | 中国地质大学（武汉） | Flow sensor, flow rate and direction determine device and method |
| CN107367543A (en) * | 2017-07-17 | 2017-11-21 | 曲阜师范大学 | Bubble measurement apparatus in molten metal based on spiral electromagnetic sensor |
| CN109839160A (en) * | 2019-03-18 | 2019-06-04 | 苏州极目机器人科技有限公司 | Flow detection device, flow rate testing methods and spray appliance |
| CN110441547A (en) * | 2019-09-04 | 2019-11-12 | 中国电建集团中南勘测设计研究院有限公司 | A kind of flow rate of water flow measurement method |
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| CN111366745A (en) * | 2020-04-30 | 2020-07-03 | 上海旭润医学科技有限责任公司 | Method for detecting extremely micro flow velocity based on computer image recognition principle |
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Application publication date: 20160420 |