CN202255495U - Empty tube detection device for electromagnetic flowmeter - Google Patents
Empty tube detection device for electromagnetic flowmeter Download PDFInfo
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- CN202255495U CN202255495U CN2011203421038U CN201120342103U CN202255495U CN 202255495 U CN202255495 U CN 202255495U CN 2011203421038 U CN2011203421038 U CN 2011203421038U CN 201120342103 U CN201120342103 U CN 201120342103U CN 202255495 U CN202255495 U CN 202255495U
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Abstract
The utility model provides a device for judging whether liquid media exist in a pipeline or not in an electromagnetic flowmeter for measuring the flow speed of fluid, namely an empty tube detection device. According to the empty tube detection device, the conductivity of the fluid media in a tube is detected in a mode of exerting exciting current on the conventional measuring electrode of the electromagnetic flowmeter instead of arranging a measuring electrode on the measuring tube, so that the conductivity is used as the basis for judging whether the measuring tube is in the empty tube state or not. The device comprises a differential amplifying circuit, a filter circuit, a power supply circuit and an exciting circuit controlled by a central processing unit (CPU) and a communication interface. According to the device, by using technologies of high-frequency sine excitation, digital encoding and decoding and the like, the conductivity of the fluid is measured continuously, the low-conductivity fluid also can be monitored, and the requirement on the distributed capacitance of a signal transmission cable is avoided.
Description
One, technical field
The utility model relates to a kind of in the electromagnetic flowmeter of measuring rate of flow of fluid, is used for judging whether pipeline exists the device of liquid medium, i.e. the blank pipe pick-up unit.This device need not increase potential electrode on testing tube, but directly on the existing potential electrode of electromagnetic flowmeter, the mode that applies exciting current is come detector tube inner fluid medium conductivity, with this as judging whether to be the foundation of empty pipe condition.This device is not only applicable to liquid-solid two-phase fluid, need measure fluid (comprising liquid and liquid-solid two-phase fluid) conductivity but also can be used for other.
Two, background technology
Electromagnetic flowmeter is to utilize Faradic electricity magnetic induction principle fluid cutting magnetic line under an excitation field to produce induced potential to measure the induced potential that the output of sensor two electrodes is directly proportional with rate of flow of fluid.Therefore, electromagnetic flowmeter mainly is a kind of instrument of measuring rate of flow of fluid.Because the electrodes exposed that blank pipe can cause electromagnetic flowmeter is introduced electromagnetic disturbance easily in air, cause the output flow velocity signal of electromagnetic flowmeter mistake; Along with the applied more and more of electromagnetic flowmeter, hope that electromagnetic flowmeter can have the ability that Quantitative Monitoring is carried out in convection cell conductance or internal resistance technically, when detecting electromagnetic flowmeter and be blank pipe, then unconditional output zero flow velocity.
Have at present and adopt the capacitive coupling high-frequency methods to come the relative change threshold detection method of fluid conductivity of discriminating sensor blank pipe fault; But adopt relative conductivity to detect existence low conductivity fluid is measured inaccurate problem; And the conductivity for liquid-solid two-phase fluid is unstable, measures the situation that is very easy to occur the erroneous judgement blank pipe; Application number be 94193261.3 patent utilization additional peak peak values for the 14V frequency be that the square wave alternating-current of 0.5Hz encourages the continuous detecting blank pipe; Non-polarizing electrode and can use the cable of high distributed capacitance to come work; But, the blank pipe detection signal influences because being easy to receive by the mobile flow noise that is produced of real fluid less than excitation frequency; And the 0.5Hz pumping signal is difficult to separate with power frequency 50Hz signal, is not suitable for power frequency simple alternating current excitation.There is publication number to solve the technology that electromagnetic flowmeter is measured low conductivity fluid for the CN1731106A patent adopts the method for serial connection excitation.Publication number has been realized convection cell measurement real-time dynamic monitoring for the CN1760643A patent adopts parallel excitation.Yet publication number is CN1731106A, CN1760643A patent all exists same problem; For the simple alternating current excitation; Its incentive measure of taking makes fluid impedance signal that additional incentive produces be difficult to separate with flow signal under the magnetic field excitation; Exist the phenomenon of disturbing to be difficult to eliminate each other, make measurement result to be forbidden.The pumping signal that publication number adopts electrode two ends serial connection to be produced by photoelectric commutator for the CN101718565A patent; A kind of high-performance flow measurement characteristic that can remain under the magnetic field excitation is provided; Again can under the excitation of additional electromotive force to the electrode two ends between fluid impedance monitor; But the circuit structure relative complexization is simultaneously because can not the continuous coverage fluid impedance, so the electromagnetic flowmeter of inapplicable power frequency simple alternating current excitation.
Therefore; For the electromagnetic flowmeter that adopts power frequency simple alternating current excitation; Quantitative dynamic monitoring is carried out in convection cell conductivity or internal resistance does not also have comparatively desirable method to be applied in the product, has hindered electromagnetic flowmeter to low cost, multifunction and the development of high reliability aspect to a certain extent.
Three, summary of the invention
The utility model purpose is in order to overcome prior art deficiency and the actual needs that satisfies product; A kind of electromagnetic flowmeter blank pipe pick-up unit that is applicable to power frequency simple alternating current excitation is provided; It has simple circuit configuration, can realize and the fluid-velocity survey signal between be separated from each other continuous measurement fluid conductivity; Also can monitor low conductivity fluid, and the distributed capacitance of signal-transmitting cable is not required.
In order to achieve the above object, the blank pipe pick-up unit of the utility model comprises a differential amplifier circuit, a filtering circuit, a power-supplying circuit and exciting circuit and the communication interface controlled by CPU.By the CPU control mouthful sinusoidal high frequency pumping electric current of generation; The conductivity that is used for test fluid flow; Be applied directly between one of them electrode and ground or two electrodes; Produce the measuring-signal of detected fluid conductivity thus, this measuring-signal and fluid conductivity are linear, and this measuring-signal is designated hereinafter simply as " blank pipe detection signal "; Through filtering circuit blank pipe detection signal and fluid-velocity survey signal are separated from each other; The blank pipe detection signal that obtains is handled through the CPU digital filtering; But continuous uninterrupted is gathered the absolute conductivity of current fluid; Blank pipe threshold through CPU inside is provided with in advance judges whether to be blank pipe.Because conductivity is only relevant with fluid media (medium) self; Through measuring its conductivity; Just can judge the characteristic of fluid accurately; Thereby be an adjustable parameter with the threshold setting that blank pipe detects, make its scope of application wider, more help solving because the liquid of residual flow on the inner-walls of duct causes the blank pipe problem of judging by accident.Not using common time-sharing multiplex detection method, adopted the continuous detecting mode, is the characteristic for the electromagnetic flowmeter that adapts to the simple alternating current excitation, and custom-designed scheme.
Because what adopt is the continuous coverage fluid conductivity; In order to reduce of the influence of blank pipe detection signal as far as possible to the flow velocity measuring-signal; Need to improve the frequency of blank pipe detection signal, could use filtering circuit being separated from each other between blank pipe detection signal and the fluid-velocity survey signal; The output flow velocity measuring-signal of electromagnet flow meter sensor is to be connected with signal converter through cable; In order to reduce extraneous electromagnetic interference (EMI), this cable uses shielded cable usually, and inevitably there is bigger distributed capacitance in this cable; The distributed capacitance of every meter length of cable even reached the capacitance of hundreds of PF; Because improving, the frequency of blank pipe detection signal helps being separated from each other with the fluid-velocity survey signal, but since the influence of cable distribution electric capacity, this distributed capacitance meeting loss blank pipe detection signal; Particularly the shielded cable of long distance can directly have influence on the test of blank pipe detection signal for fluid conductivity.In order to address the above problem; Guarantee the faint distortionless transmission of blank pipe detection signal, the blank pipe pick-up unit is positioned over the outlet of electromagnet flow meter sensor nearby, and sinusoidal high frequency pumping electric current is applied directly to; Between one of them electrode of electromagnet flow meter sensor and ground or two electrodes; The signal between electromagnet flow meter sensor and the signal converter is directly opened or closed to the blank pipe pick-up unit through judging the blank pipe detection signal, do not have flow velocity signal output when having realized blank pipe; Promptly when detecting electromagnetic flowmeter and be blank pipe, then unconditional output zero flow velocity;
The blank pipe pick-up unit is positioned over the outlet of electromagnet flow meter sensor nearby, has thoroughly solved the requirement of high-frequency blank pipe detection signal to the cable distribution capacitance size.Owing to only be useful on two core shielded cables of MPTS speed measuring-signal between electromagnet flow meter sensor and the signal coverter usually; Do not have the low-voltage dc power supply supply cable; In order to satisfy general installation custom; No longer the blank pipe pick-up unit is increased service cable in addition, the power supply of blank pipe pick-up unit uses wherein lead of two core shielded cables to supply power, and an other lead is used to transmit the measuring-signal through the flow velocity after the conditioning;
The blank pipe threshold parameter of blank pipe pick-up unit is provided with, and then uses digital modulation mode, is superimposed upon on the cable of power supply to transmit, because digital encoding and decoding are known technology, so here do not describe.
The blank pipe pick-up unit of the utility model not only can be used for the electromagnetic flowmeter on the hog barge, also can be used for the situation that other need measure fluid (comprising liquid and liquid-solid two-phase fluid) conductivity or internal resistance and use power frequency simple alternating current excitation.
In the electromagnetic flowmeter product, behind the blank pipe testing product of employing the utility model, quantitative real-time dynamic monitoring is carried out in electromagnetic flowmeter realization convection cell conductivity or internal resistance, also can monitor low conductivity fluid; And and be separated from each other between the fluid-velocity survey signal, and adopt the continuous coverage mode, in order to adapt to the conductivity sudden change problem of liquid-solid two-phase fluid, use digital filtering algorithm, it is simple to have a circuit structure, has also improved the accuracy rate that blank pipe detects simultaneously; The blank pipe pick-up unit is positioned over the outlet of electromagnet flow meter sensor nearby, to the characteristics that the distributed capacitance size of signal-transmitting cable does not require, more helps the electromagnetic flowmeter product to low-cost, multifunction and the development of high reliability aspect.
Four, description of drawings
Fig. 1 is a kind of electrical block diagram of original electromagnetic flowmeter
Fig. 2 is a kind of electrical block diagram of electromagnetic flowmeter of original band blank pipe detection
Fig. 3 is the electrical block diagram that applies the electromagnetic flowmeter of blank pipe detection signal between an electrode and the ground
Fig. 4 is the electrical block diagram that applies the electromagnetic flowmeter of blank pipe detection signal between two electrodes
Five, embodiment
See in Fig. 1 synoptic diagram; Electromagnet flow meter sensor is under AC excitation; Produce alternating magnetic field; Conductive fluid cutting magnetic line in alternating magnetic field produces induced potential E1, exports the master control circuit board of remote signaling converter to through shielded cable, output flow velocity signal and showing on master control circuit board.
See in Fig. 3, Fig. 4 synoptic diagram; Controlling a mouthful generation cycle by CPU is the high frequency pumping of 16us; Through analog-converted is high frequency sinusoidal excitation E2, and this sinusoidal excitation is applied directly to, between one of them electrode of electromagnet flow meter sensor and ground or two electrodes; (Fig. 3 is the circuit structure diagram that applies the electromagnetic flowmeter of blank pipe detection signal between an electrode and the ground, and Fig. 4 is the circuit structure diagram that applies the electromagnetic flowmeter of blank pipe detection signal between two electrodes); Produce the measuring-signal U1 of detected fluid internal resistance R1 thus, this measuring-signal U1 and the linear U1=K*R1 of fluid internal resistance R1 (K is a known coefficient).Inevitably fluid internal resistance measurement signal and rate of flow of fluid measuring-signal exist simultaneously, and the two mixes, and through high-pass filtering circuit the blank pipe detection signal are extracted again; This moment to flow velocity signal attenuation more than 60dB; Through the CPU real-time sampling and through behind the digital filtering, compare with preset threshold (adjustable parameter), if be judged as blank pipe; Then CPU sends the zero signal; Closing Switch K1 closes the fluid-velocity survey signal at once, make signal converter be shown as zero, otherwise cut-off switch K1 normally exports flow velocity signal.And the flow velocity measuring-signal is exported flow velocity signal through behind the signal conditioning circuit to more than the blank pipe detection signal decay 60dB through low-pass filter circuit this moment again on the electrode, and realization is separated from each other with the blank pipe detection signal, thereby guarantees the accuracy of fluid-velocity survey.
See in Fig. 2 synoptic diagram; Be a kind of circuit structure diagram of electromagnetic flowmeter of original band blank pipe detection, because the influence of cable distribution electric capacity, this distributed capacitance has certain loss to high-frequency blank pipe detection signal; Particularly grow the shielded cable of distance; Can directly have influence on of the test of blank pipe detection signal for fluid conductivity, thus this structure and being not suitable for, the radio-frequency signal blank pipe detection mode that the utility model proposes.Can find out in order to guarantee the faint distortionless transmission of blank pipe detection signal in conjunction with Fig. 3 and Fig. 4; The blank pipe pick-up unit is positioned over sensor outlet (sensor internal) nearby; Carry out transmitting through shielded cable again after the signal Processing, thereby thoroughly solved of the requirement of high-frequency blank pipe detection signal completely the cable distribution capacitance size.
Owing to only be useful on two core shielded cables of MPTS speed signal between electromagnet flow meter sensor and the signal coverter usually; Do not have the low-voltage dc power supply supply cable; In order to satisfy general installation custom; No longer the blank pipe pick-up unit is increased service cable in addition, the power supply of blank pipe pick-up unit uses wherein lead of two core shielded cables to supply power, and an other lead is used to transmit the flow velocity signal through after the conditioning; Realize that direct current supply and signal transmit shared one two core shielded cable.
According to different environments for use; When the blank pipe threshold parameter that the signal coverter need be adjusted the blank pipe pick-up unit is provided with; Then use digital signal modulation mode; This signal is superimposed upon on the cable of power supply and transmits, and the convenient parameter of adjusting the blank pipe pick-up unit at the scene satisfies different service conditions.Because digital encoding and decoding are known technology, so here do not describe in detail.
The above; Be merely the preferable embodiment of the utility model; But the protection domain of the utility model is not limited thereto; Any technician who is familiar with the present technique field is in the technical scope that the utility model discloses, and the variation that can expect easily or replacement all should be encompassed within the protection domain of the utility model.Therefore, the protection domain of the utility model should be as the criterion with the protection domain of claims.
The content of not doing in this instructions to describe in detail belongs to this area professional and technical personnel's known prior art.
Claims (7)
1. an electromagnetic flowmeter blank pipe pick-up unit that is applicable to power frequency simple alternating current excitation comprises an electromagnet flow meter sensor and the blank pipe pick-up unit circuit that power frequency simple alternating current excitation is arranged, and base is characterised in that:
Electromagnet flow meter sensor is under the industrial frequency AC excitation; Produce alternating magnetic field; Conductive fluid cutting magnetic line in alternating magnetic field produces the induced potential signal, and two electrodes through on the electromagnet flow meter sensor export blank pipe pick-up unit circuit to; After this circuit of process is nursed one's health signal, export electromagnetic flowmeter signal converter to through cable again.
2. based on the blank pipe checkout gear described in the claim 1; It is characterized in that producing in the described circuit high frequency square wave excitation; Convert the high frequency sinusoidal excitation signal into through analog circuit, this sinusoidal excitation signal is applied directly to, between one of them electrode and ground of electromagnet flow meter sensor;
3. based in the blank pipe checkout gear described in the claim 1; It is characterized in that producing in the described circuit high frequency square wave excitation; Convert the high frequency sinusoidal excitation signal into through analog circuit, this sinusoidal excitation signal is applied directly to, between two electrodes of electromagnet flow meter sensor;
4. according in the blank pipe pick-up unit described in the claim 1; It is characterized in that described circuit is positioned over the outlet of electromagnet flow meter sensor electrode (or sensor internal) nearby, through passing through cable transmission after the signal Processing again to electromagnetic flowmeter signal converter.
5. according in the blank pipe pick-up unit described in the claim 1; It is characterized in that described circuit is to have a high-pass filtering circuit to incite somebody to action; The high frequency sinusoidal excitation signal that is used for the blank pipe detection signal extracts; Have a low-pass filter circuit to incite somebody to action, the induced potential signal extraction of electromagnet flow meter sensor is come out; The induced potential signal of realizing high frequency sinusoidal excitation signal and sensor is separated from each other.
6. according in the blank pipe pick-up unit described in the claim 1, it is characterized in that with twin core cable that electromagnetic flowmeter signal converter is connected on, wherein a lead is supplied power, an other lead is used to transmit the flow velocity signal through after the conditioning; The transmission of power supply and flow velocity signal is a shared twin core cable.
7. according in the blank pipe pick-up unit described in the claim 1, it is characterized in that stack is used for transmitting data between blank pipe pick-up unit and the electromagnetic flowmeter signal converter through modulated digital signal on service cable.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2011203421038U CN202255495U (en) | 2011-09-14 | 2011-09-14 | Empty tube detection device for electromagnetic flowmeter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2011203421038U CN202255495U (en) | 2011-09-14 | 2011-09-14 | Empty tube detection device for electromagnetic flowmeter |
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| Publication Number | Publication Date |
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| CN202255495U true CN202255495U (en) | 2012-05-30 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN2011203421038U Expired - Fee Related CN202255495U (en) | 2011-09-14 | 2011-09-14 | Empty tube detection device for electromagnetic flowmeter |
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| CN (1) | CN202255495U (en) |
Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103557894A (en) * | 2013-11-14 | 2014-02-05 | 中环天仪股份有限公司 | Empty pipe signal separation circuit for electromagnetic flowmeter |
| CN103743443A (en) * | 2013-11-08 | 2014-04-23 | 上海大学 | Method for detecting signal faults of electromagnetic flow meter |
| CN104395699A (en) * | 2012-08-21 | 2015-03-04 | 克洛纳有限公司 | A Magnetic-inductive flowmeter having a plurality of functional units |
| CN106643927A (en) * | 2016-12-16 | 2017-05-10 | 杭州盘古自动化系统有限公司 | Low power consumption dormant electromagnetic flowmeter and controlling method |
| CN110770546A (en) * | 2017-11-07 | 2020-02-07 | 高砂电气工业株式会社 | Fluid device |
| CN111238586A (en) * | 2020-03-27 | 2020-06-05 | 上海市计量测试技术研究院 | Electromagnetic flowmeter for measuring low conductivity and rate measuring method thereof |
| CN112050871A (en) * | 2020-08-25 | 2020-12-08 | 长江武汉航道工程局 | Dredger pipeline transportation passive yield meter |
| CN112050870A (en) * | 2020-08-20 | 2020-12-08 | 长江武汉航道工程局 | Curve reduction anti-interference measuring device and method thereof |
| CN112050869A (en) * | 2020-08-20 | 2020-12-08 | 长江武汉航道工程局 | Continuous alternating magnetic field measuring device and method thereof |
| CN115507904A (en) * | 2022-07-21 | 2022-12-23 | 浙江迪元仪表有限公司 | Electromagnetic water meter |
-
2011
- 2011-09-14 CN CN2011203421038U patent/CN202255495U/en not_active Expired - Fee Related
Cited By (16)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104395699A (en) * | 2012-08-21 | 2015-03-04 | 克洛纳有限公司 | A Magnetic-inductive flowmeter having a plurality of functional units |
| CN104395699B (en) * | 2012-08-21 | 2018-03-30 | 克洛纳有限公司 | Magnetic induction flowmeter with multiple functional units |
| CN103743443A (en) * | 2013-11-08 | 2014-04-23 | 上海大学 | Method for detecting signal faults of electromagnetic flow meter |
| CN103557894B (en) * | 2013-11-14 | 2016-02-24 | 中环天仪股份有限公司 | A kind of separation circuit of electromagnetic flowmeter air-control signal |
| CN103557894A (en) * | 2013-11-14 | 2014-02-05 | 中环天仪股份有限公司 | Empty pipe signal separation circuit for electromagnetic flowmeter |
| CN106643927A (en) * | 2016-12-16 | 2017-05-10 | 杭州盘古自动化系统有限公司 | Low power consumption dormant electromagnetic flowmeter and controlling method |
| CN110770546B (en) * | 2017-11-07 | 2021-02-19 | 高砂电气工业株式会社 | Fluid device |
| CN110770546A (en) * | 2017-11-07 | 2020-02-07 | 高砂电气工业株式会社 | Fluid device |
| CN111238586B (en) * | 2020-03-27 | 2021-08-20 | 上海市计量测试技术研究院 | Electromagnetic flowmeter for measuring low conductivity and rate measuring method thereof |
| CN111238586A (en) * | 2020-03-27 | 2020-06-05 | 上海市计量测试技术研究院 | Electromagnetic flowmeter for measuring low conductivity and rate measuring method thereof |
| CN112050870A (en) * | 2020-08-20 | 2020-12-08 | 长江武汉航道工程局 | Curve reduction anti-interference measuring device and method thereof |
| CN112050869A (en) * | 2020-08-20 | 2020-12-08 | 长江武汉航道工程局 | Continuous alternating magnetic field measuring device and method thereof |
| CN112050871A (en) * | 2020-08-25 | 2020-12-08 | 长江武汉航道工程局 | Dredger pipeline transportation passive yield meter |
| CN112050871B (en) * | 2020-08-25 | 2023-09-19 | 长江武汉航道工程局 | Pipeline conveying passive obstetric meter for dredger |
| CN115507904A (en) * | 2022-07-21 | 2022-12-23 | 浙江迪元仪表有限公司 | Electromagnetic water meter |
| CN115507904B (en) * | 2022-07-21 | 2024-02-23 | 浙江迪元仪表有限公司 | Electromagnetic water meter |
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| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
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Addressee: Wuhan Boguang Systems Engineering Co., Ltd. Document name: Notification of Termination of Patent Right |
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| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20120530 Termination date: 20140914 |
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| EXPY | Termination of patent right or utility model |