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Measurement principle of Ross Mont mass flowmeter and its application in petroch

Release time:2019-06-16

 


Measurement principle of Ross Mont mass flowmeter and its application in petrochemical industry -
2. Principle of density measurement
 
One end of the flow tube is fixed while the other end is free. This structure can be regarded as a heavy material / spring system suspended in a spring. Once it is applied to a motion, the system will vibrate at its resonant frequency, which is related to the mass of the weight. The flow tube of mass flowmeter is vibrated on its resonant frequency through the driving coil and feedback circuit. The resonant frequency of the vibration tube is related to the structure, material and quality of the vibration tube. The quality of the vibrating tube consists of two parts: the quality of the vibrating tube itself and the quality of the medium in the vibrating tube. When each sensor is produced, the quality of the vibration tube itself is determined. The mass of the medium in the vibration tube is the product of the medium density and the volume of the vibration tube, and the volume of the vibration tube is fixed for each caliber sensor, so the vibration frequency is directly related to the density, so that the structure and the material are determined. The material density of the material can be obtained by measuring the resonant frequency of the flow tube.
 
A signal detector using a flow measurement can obtain a signal representing the resonant frequency. The signal of a temperature sensor is used to compensate for the change of the steel property of the flow tube caused by the temperature change. The measurement of the vibration period is obtained by measuring the vibration period and temperature of the flow tube. The measurement of the dielectric density uses the density and flow rate. The linear relationship between tube vibration period and standard calibration constant.
 
When the density of the Coriolis mass flow sensor is measured by the vibration tube, the natural frequency of the pipe is determined by the steel, geometric structure and flow quality of the pipe, so the fluid density can be deduced from the measured pipe frequency. The transmitter uses a high frequency clock to measure the time of the vibration cycle. The measured value is filtered by digital, and the density coefficient is used to calculate the process fluid density with the calibration coefficient of the sensor density after compensating the change of the pipeline steel nature by the operating temperature and causing the change of the natural frequency.