Interest in mass flow meters has steadily increased over the past decade. Mass flow meters have been widely used in food, beverage, chemical, pharmaceutical, oil, natural gas and other industries. Along with people's attention, the performance of mass flow meter is also constantly developing. Its biggest advantage is that it can directly measure mass flow, while other instruments can only measure volume flow. The high precision, wide range and repeatability of the mass flowmeter are further reasons for its wide application and rapid development in the industrial field.
The driving circuit of the mass flowmeter generates a specific driving pulse to make the tube vibrate at a certain amplitude. When the properties of the fluid change, the drive circuit must respond quickly. For example, when air bubbles are mixed into the fluid, the damping will increase rapidly, which requires the system to quickly provide more excitation energy to ensure a stable oscillation amplitude. The excitation frequency should be consistent with the resonance frequency of the system, which requires that the drive circuit can not only control the oscillation amplitude, but also control the oscillation frequency. The dynamic response performance of the mass flowmeter is a very important factor in some applications such as fast control operations, periodic flow fluctuations, and rapid batch irrigation.
The sensor obtains a weak sinusoidal signal, which needs to be amplified before further information processing. The amplifier used should have a large bandwidth to reduce the additional zero point error. In the phase difference measurement of the coriolis type mass flow meter. The amplitude ratio measurement method and the direct measurement method of time difference are mainly realized by analog circuits, which can be called analog. Analog circuits are less stable. It is easily affected by factors such as ambient temperature, which ultimately affects its measurement accuracy. Using Fourier transform algorithm, supplemented by phase-locked loop technology, using dual-channel high-speed and high-precision A/D chips to sample the two sensor signals synchronously. With the digital signal processor DSP as the operation core, the phase difference and frequency of the two signals are calculated in real time, so as to obtain information such as the mass flow rate and density of the fluid, realizing the transformation from analog to digital. Compared with traditional analog. The influence of the analog circuit on the phase difference measurement is reduced. The Fourier algorithm is used to transform the signal from the time domain to the frequency domain for spectrum analysis, which can analyze and process the signal more accurately, effectively and quickly, effectively suppress the interference of high-order harmonics and noise, and improve the phase difference and Frequency measurement accuracy, thereby improving the measurement accuracy of the mass flowmeter.
1) Its anti-corrosion, anti-fouling, explosion-proof, wear-resistant and other problems have been satisfactorily solved, so it can measure a wide range of media, such as oil products, chemical media, papermaking black liquor, slurry, gas, fluids of solid particles and highly viscous objects.
2) There are no obstacles in the pipeline, no moving parts, less failure factors, and easy cleaning, maintenance and maintenance.
3) Easy to install, the inlet and outlet directions of sensor pipes of various sizes can be adjusted at will. Installation: adjustment, easy to use, no need to configure straight pipe sections for inlet and outlet.
4) It is easier to measure multiphase fluids.
5) Multi-parameter measurement, while measuring mass flow, volume flow, temperature and density can be obtained at the same time; it is not sensitive to influencing quantities, such as pressure, temperature, density and viscosity, and flow velocity distribution.
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