PARAMETRIC STUDY OF VIBRATION BASED ELECTROMECHANICAL CORIOLIS MASS FLOW SENSOR

Abstract

The amount of mass of liquid that flows all the way through certain cross sectional area per second is termed as mass flow rate. In many industrial process operations such as custody transfer operations, recipe formulations and material balance determination, precise sensing of mass flow rate is very crucial. The fluid volume is a function of ambient temperature and pressure, while the _ mass is unchanged by changes in temperature or pressure. Therefore, mass flow sensing is more reliable measure of flow in high accuracy systems. Liquid flow meters are used in various applications for monitoring and control purposes. Over the years several types of flow meters both disruptive as well as non - disruptive have been devised, developed and tested successfully. The concept of Coriolis mass flow metering was developed and physically realized in the mid 1980's. Since then it has been established as the most accurate techniques commonly employed in an industrial flow measurement technology, with worldwide revenues presently greater than $500 million and moving to $700 million in near future, Coriolis technology is considered as market leader mass flow sensing technology by many. A major cause for this unique development is its capability to measure single phase fluids with accuracy and repeatability of ± 0.2% FSD or less; which without question makes it the most accurate general purpose meter used by industry. It has been used successfully in wet-gas with at most 2.5% of liquid. The Coriolis mass flow measuring devices operate by making use of an oscillating tube (typical range of dia 1- 300 mm), at the natural frequency of selected mode of vibration, called as drive mode. The two sensors monitor the vibrations of the flow tube as the process fluid passes through. The frequency of oscillation typically ranges from 20 Hz to 1 KHz depending on the flow tube geometry. The geometry of the flow tube is so arranged such that the Coriolis force acts to results in the phase difference between the two limbs of the tube.