CN2427798Y - Multiple electrode flow rate measuring signal processing device - Google Patents

Abstract

The utility model discloses a multielectrode type flow-rate measuring signal processor. After induced electromotive force which is generated when fluids flow across a multielectrode sensor is input into an impedance amplifying/converting circuit, signals are input into an instrument amplifier for signal amplification by a multipoint selection type electronic diverter switch which is controlled by a computer, delivered to a filter circuit at a lower level for high and low pass filtration through a synchronous sampling circuit, and then transformed to an A/D translation circuit after amplified by a signal amplifying circuit, and the data that are translated by the A/D translation circuit are input into a computerized data processing system and displayed on an LCD screen. The utility model has the advantages of simple structure, convenient operation and lower requirement of the installation of a flowmeter.

Description

Multi-electrode flow detecting signal processor

The utility model relates to the application electromagnetic flowmeter, relates in particular to a kind of multi-electrode flow detecting signal processor.

Existing electromagnetic flowmeter has been widely used in many industrial processes such as water supply and sewage work, wastewater treatment and medicine, food, weaving.Its principal feature is the sensor no-movable part, and fluid flow is noiseless substantially, can produce the additional pressure loss by convection cell hardly; Parameters such as the working pressure of measurement result and detected fluid, temperature, viscosity are irrelevant.Existing electromagnetic flowmeter is general main to be made up of three parts such as sensor, field power supply, signal amplification and treatment circuits.Nearly all sensor all adopts pair of electrodes, and electrode is installed in tube wall, and the line of electrode is perpendicular to magnetic field.Owing on the sensor construction, be the measuring accuracy of dependable flow meter, require flow rate of fluid to be distributed as axial symmetry, for this reason, before flowmeter enough flow development lengths will be arranged during installation, this makes the application of flowmeter bring the application of certain limitation, particularly heavy caliber flowing meter.

The purpose of this utility model provides a kind of simple in structure, easy to use, reduces the multi-electrode flow detecting signal processor of flowmeter installation requirement.

The utility model is taked following measures in order to achieve the above object:

Fluid is flowed through after induced potential that sensor produces amplifies translation circuit via high resistant input impedance, select electronic switch by PC104 computer control multiple spot, signal is imported instrument amplifier carry out the signal amplification, then by the synchronized sampling circuit, carry out synchronized sampling and keep according to the time ordered pair input signal of synchronization control circuit, and this signal is delivered to the next stage filtering circuit carry out height, low-pass filtering, signal being delivered to signal amplification circuit does further to amplify again, deliver to the A/D change-over circuit, data after the A/D conversion, read in via the PC104 computing machine, the PC104 computer system is read in each and is carried out data processing to electrode signal, and analysis and solution is gone out velocity flow profile and instantaneous delivery on the cross-section of pipeline, integrated flux, and on the LCD screen, show velocity profile, and instantaneous delivery, the integrated flux parameter.

The utility model is simple in structure, easy to use, and the electromagnetic flowmeter that adopts the utility model to make also has following advantage:

1, according to each the interelectrode electromotive force that records, can obtain the velocity flow profile on the measuring section tube section;

2, can obtain the mean flow rate of fluid by velocity flow profile or directly utilize each electrode to quadrature with respect to the potential value of reference electrode to obtain mean flow rate, whether this mean flow rate and fluid are that rotational symmetry is irrelevant in ducted velocity flow profile;

3, because the mean flow rate of flowmeter output is not subjected to the influence of velocity flow profile, therefore flowmeter does not need special straight length when mounted in principle, thereby greatly reduces the installation requirement of flowmeter;

4, when the flowmeter level is installed, whether whether unusual according to the potential value that is positioned at each electrode of level top, can differentiate fluid is non-full pipe, but and the non-full pipe degree of estimating of fluid.

Below in conjunction with accompanying drawing the utility model is elaborated.

Fig. 1 is the electric principle schematic of the flow detecting signal processor of band multi-electrode flow sensor;

Fig. 2 is the electrical schematic diagram of synchronized sampling circuit;

Fig. 3 is a multi-electrode flow sensor structural representation;

Fig. 4 is the electrode structure synoptic diagram.

As shown in Figure 1, when conductive fluid is flowed through sensor 1, because behind the cutting magnetic line of force that field coil produced, between each electrode, produce the induced potential that differs in size, after this induced potential amplifies translation circuit 2 via high resistant input impedance, select electronic switch 3 by PC104 computing machine 9 control multiple spots, select different input electrode passages, signal is imported the signal that instrument amplifier 4 carries out about 1,000 times to be amplified, then by synchronized sampling circuit 5, carry out synchronized sampling and keep according to the time ordered pair input signal of synchronization control circuit 11, and this signal is delivered to next stage filtering circuit 6 carry out height, low-pass filtering is delivered to signal signal amplification circuit 7 again and is done further to amplify, deliver to A/D change-over circuit 8, data after A/D conversion after reading in via PC1049, are carried out data processing.

PC104 computer system 9 is read in each to electrode signal, and according to accurate algorithm, and analysis and solution is gone out velocity flow profile and instantaneous delivery on the cross-section of pipeline, integrated flux etc., and on LCD screen 10, show velocity profile, and instantaneous delivery, parameters such as integrated flux.

As shown in Figure 2, utilize the keying with the synchronous clock signal control electronic switch S of excitation signal, respectively the positive half cycle of ac input signal (synchronous with excitation) and negative half period are sampled and keep, and carry out signal Processing by computing machine.

C keeps electric capacity for sampling among the figure, after electronic switch S connects, and U ₂Output feedback amplifier U ₁End of oppisite phase realized the high impedance input of signal, also to make the charge conversion that keeps on the electric capacity be Low ESR output to this circuit simultaneously, made it to guarantee the undistorted rate of sampled signal.

Sampling keeps electric capacity must select the polypropylene capacitor of the little low adsorption effect of electric leakage for use.

This circuit can be controlled S by synchronizing signal, realizes easily each data acquisition to electrode, and signal keeps, so that carry out the A/D conversion.

Circuit connecting relation is as follows:

Input signal U _iAdd amplifier U ₁In-phase end; U ₁End of oppisite phase respectively with U ₂End of oppisite phase and U ₂Output link to each other U ₁Output link to each other with the input of electronic switch; The output of electronic switch links to each other with input resistance R with keeping capacitor C respectively; Keep capacitor C other end ground connection; The input resistance R other end and amplifier U ₂In-phase end link to each other; U ₂Output link to each other with end of oppisite phase, constitute impedance transducer, realize low-resistance output; Electronic switch controling end S is by the synchronous control signal control of external circuit PC104 computing machine.

As shown in Figure 3, the multi-electrode flow sensor has sensor housing 13, on the sensor housing periphery, be provided with 4～24 electrode fixing holes, on sensor housing inwall and electrode fixing holes inwall, be provided with teflon insulation liner 14, in being provided with the teflon-lined electrode fixing holes, be provided with electrode 12, coil 15 arranged at the sensor housing peripheral hardware.Said electrode one end is a reverse taper, and the tapering of reverse taper is 30 °, and the surface in contact of electrode and fluid is that radius is the curved surface of R, and the other end is provided with the fixedly fixing internal thread of external thread and sensor lead of electrode.

The computing method of electromagnetic flowmeter velocity flow profile are as follows:

Any two interelectrode induced potential △ E are according to the Faradic electricity magnetic induction principle:

△E=∫∫WひdA

ひ is a velocity field in the formula; W is called the vector weight function, and it is relevant with the exciting method and the electrode structure of electromagnetic flowmeter.Cross-section of pipeline is divided into several infinitesimals,,, when flowing, has for two-dimensional flow then for any pair of electrodes i as m

△Ei=∑WijVj△Aj(i=1，2…，j=1，2，…m)

Wij and Vj are respectively for weight function value and the flow velocity of i to electrode on little △ Aj in the formula.Above equation is one group of typical system of linear equations.Infinitesimal dividing method Wij and △ Aj for a specific sensor and regulation are known constant, and △ Aj is the potential measurement value, then utilize the least square solution can try to achieve flow speed value Vj at infinitesimal j place, thereby obtain the velocity flow profile on the cross-section of pipeline.

Distribution is averaged to known flow rate, can obtain the mean flow rate V of pipeline inner fluid $V=\frac{1}{m}\underset{j=1}{\overset{m}{\mathrm{\Σ}}}\mathrm{vj\Δ\&Agr;j}/\underset{j=1}{\overset{m}{\mathrm{\Σ}}}\mathrm{\Δ\&Agr;j}$ If only need mean flow rate, then utilize following integration type directly to try to achieve $V=\frac{1}{\mathrm{\π}}{\∫}_{\mathrm{\&ogr;}}^{2\mathrm{\π}}\frac{1}{B}\mathrm{\μ}\left(\mathrm{\θ}\right)\cos \mathrm{\θd\θ}$

Accompanying drawing 1 is seen in the definition of θ in the formula, and U (θ) is the current potential at the induced potential at θ cornue wall place.When electrode when discrete, following formula is a summation formula.

Implementation method is as follows:

Below main narration the utility model and the different implementation method of existing pair of electrodes electromagnetic flowmeter.

1, under the situation of field power supply effect, make sensor be full of water the output zero point of each passage of metering circuit, is zero point, and the zero point that is kept at PC104 is in the file.

2, the relative enlargement factor of measuring-signal amplification and each passage of treatment circuit.Before signal amplification and treatment circuit each passage is added onesize standard signal, each interchannel relative enlargement factor is obtained in the output of measuring each passage, is kept in the enlargement factor file of PC104.

3, survey nonuniformity coefficient.Sensor is installed on the caliberating device, regulates flow to 80～90% of flowmeter full scale.Measure the relative value of each electrode pair induced potential, under ideal state, to the due relative potential value of each electrode pair relatively, obtain the nonuniformity coefficient of each electrode pair electromotive force, be kept in the nonuniformity coefficient file of PC104.

4, when actual measurement, the output valve that the actual value of every pair of electrode measurement induced potential should be this electrode pair institute respective channel and the difference at this passage zero point multiply by the relative enlargement factor of this passage, multiply by the nonuniformity coefficient that this is answered electrode pair more at last.

Claims (2)

1. multi-electrode flow detecting signal processor is characterized in that:

Fluid is flowed through after induced potential that sensor [1] produces amplifies translation circuit [2] via high resistant input impedance, select electronic switch [3] by PC104 computing machine [9] control multiple spot, signal is imported instrument amplifier [4] carry out the signal amplification, then by synchronized sampling circuit [5], carry out synchronized sampling and keep according to the time ordered pair input signal of synchronization control circuit [11], and this signal is delivered to next stage filtering circuit [6] carry out height, low-pass filtering, signal being delivered to signal amplification circuit [7] does further to amplify again, deliver to A/D change-over circuit [8], data after the A/D conversion, via PC104[9] read in after, entering PC104 computer data processing system [9] reads in each to electrode signal, analysis and solution is gone out velocity flow profile and instantaneous delivery on the cross-section of pipeline, integrated flux, and at the last demonstration of LCD screen [10] velocity profile, and instantaneous delivery, the integrated flux parameter.

2. a kind of multi-electrode flow detecting signal processor according to claim 1, it is characterized in that: said synchronized sampling circuit [5] is: input signal [U _i] adding amplifier U ₁In-phase end; [U ₁] end of oppisite phase respectively with [U ₂] end of oppisite phase and [U ₂] output link to each other [U ₁] output link to each other with the input of electronic switch; The output of electronic switch links to each other with input resistance [R] with keeping electric capacity [C] respectively; Keep electric capacity [C] other end ground connection; Input resistance [R] other end and amplifier [U ₂] in-phase end link to each other; [U ₂] output link to each other with end of oppisite phase, constitute impedance transducer, realize low-resistance output; Electronic switch controling end [S] is by the synchronous control signal control of external circuit PC104 computing machine.

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