Technical field measurement technology, the invention relates to liquid concrete as a kind of coal with vortex flowmeter
Technical background of vortex flowmeter is applied to the liquid flow testing, both at home and abroad extensive use in petroleum, chemical, food, medicine, refining and other industries.
Traditional dizzy vortex flow meter by the flow tube, triangular prism, sensors, signal processing and display, etc, according to principle of karman vortex street when flow in the pipe fluid flow through, as a result of the existence of triangular prism, will produce resistance, make the fluid diversion, so that in the front of the sensor will produce eddy current, and for fear of eddy current sensor signal is induced, and the number of them to the signal processing system, through the analysis and calculation, in the form of Numbers in the display it in the show: the main problems existing in the structure form of the flowmeter is: 1, axial have beat effect: when use, because many of the flowmeter and pump body connection, mostly due to the vibration of the pump is very big, can produce levels of vibration, lead to flow tube flowmeter with vibration, so also affected the eddy current in the normal production and affect the measurement result: 2, small flow rate is not very * : the vortices generated when the small flow rate is small, the sensor produces induction signal value, lead to small flow metering is not very * : 3, the signal acquisition system is composed of triangular prism and sensors, the production cost is high.
Vortex flow signal has the following characteristics: 1, the signal spectrum width, the typical signal spectrum from 0.
3 hz to 3500 hz.
Across 13 octave above: 2, wide range than, 100:1.
The vortex signal intensity is proportional to the signal frequency of vortex street square, the signal amplitude difference is as high as 10000 times.
Vortex street flowmeter in actual application, because of the precision and accuracy of piping installation, straight pipe length less than lead to widespread strong low frequency of the spectrum of the signal,
Relative to the vortex signal)
Flow disturbance, and other such as noise, resonance interference, pipes, mechanical vibration and other kinds of interference signals to cover the entire spectrum.
Conventional vortex signal processing circuit, refer to figure 1, according to the vortex signal amplitude frequency characteristics, the inherent flow sensor acquisition signal after charge amplifier, using frequency equalizer amplification, limiting clamp amplifier circuit way, amplify the signal amplitude to the same level, so that after the magnitude frequency detection circuit, and then complete the conversion of frequency and current, the traditional signal processing methods can handle only about 10:1 mileage signal, the range of street for actual of up to 100:1 of the vortex signal, the low frequency interference caused by frequency equilibrium signal is amplified by a wide margin, and instead flooded a real vortex signal, after the magnitude frequency detection circuit to produce & other;
Leaky wave & throughout;
Phenomenon, and even mistaken identification for the flow of low frequency interference signal to faint signal, the accuracy of the sharp drop, while limiting circuit in essence of strongly nonlinear harmonic spawn, lead to signal and the frequency points intermodulation, makes the signal spectrum degradation, interfere with or even destroy the real signal frequency of vortex street to pick up, reduce the accuracy of vortex flow sensor.
Content of the invention of the present invention solves technical problems is to provide a coal mine in vortex flowmeter, in order to solve the above problems in technical background.
The invention solves the technical problems in using the following technical scheme: a coal mine in vortex flowmeter, including: flow tube, as described in the flow tube set triangular prism, it is triangular prism set on the back of the probe, the corresponding location of the flow tube and probe the external Settings * magnets, to probe and * magnet signal sensor described: referred to probe for needle conductive body, vertical suspended in the middle of the measuring tube, the tail end of the probe in the outside of the discharge pipe, and connecting terminal, detecting signal leads in the terminal, probe the terminal connected to the signal processing system.
Optimization, signal processing system including OP281 M430F147 by single-chip microcomputer, digital circuit, OP193, signal amplifying circuit and LCD liquid crystal display, signal amplification circuit connection between the probe and microcontroller M430F147 optimization, as described in the output of the signal amplifying circuit for charge amplifier module by the coupling capacitor C1, resistance RI to the op-amp UIA 2 feet, 2 feet of UIA connected to the output Z foot feedback capacitance C2 and concatenated feedback resistor R3 and R4, of the op-amp U1A 3 feet grounded after connecting balance resistance R2, the output of the op-amp U1A except for sequence circuit after also access on the bleeder resistor R7, on the other side of the bleeder resistor R7 and R8 partial pressure resistance together with the access transistor Ql of the base, the partial pressure resistance R8 the other side grounding, grounding the emitter of the transistor Q1, C4 collector respectively with resistance R6, capacitance connected to the anode, the field effect tube grid of Q2, resistance R6 connection positive, on the other side of the capacitor C4 cathode connecting power supply midpoint, Q2 drain field effect tube connected to the anode with resistance RS, capacitor C3, Q2 field-effect tube connected to the source resistance RS and the positive, followed by the power capacitor C3 cathode and charge amplifier module in the feedback resistor R3, R4, respectively.
When the flow in the pipe fluid flow through, as a result of the existence of triangular prism, produce resistance, cutting fluids, thus produces eddy: in front of the probe at the same time in this position because of the existence of * magnet produces a strong magnetic field, eddy current will generate induced electromotive force, the probe will therefore generate induced electromotive force and as a detection signal output, again by the subsequent signal processing system analysis and calculation, it to show in the form of Numbers in the display.
There are a wide variety of which are scientifically tested to have positive effects on the ability to u shape coriolis mass flow meter. insertion ultrasonic flow meter mass flow meter is one of them.
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