National Metal and Refining Company, Ltd.

National Metal Refining Company

Natonal Metal and Refining Company, Inc.

John V Fitzgerald

Teresa M Walsh

Frank J Matusik

Edmond J Dougherty

John L Batton

John Stone

John Batton

A transducer for inline process control of highly viscous fluids at high pressure and high temperature having a torsionally oscillating sensor tip supported by a pressure resistant threaded body portion. The sensor tip, which includes a thermocouple to measure fluid temperature, is driven by a crossarm which oscillates with a constant angular amplitude, the power required to maintain that amplitude despite the viscous resistance offered by the fluid being a measure of the viscosity-density product of the fluid. The crossarm driver and detector electromagnetic coils are oriented at right angles to each other to reduce crosstalk and transducer housing diameter. The associated electronic control unit includes means to compensate for the effects of fluid flow rate and fluid pressure which were found to be encountered with the vibratory viscometer method of measurement when inline measurements are made on high viscosity fluids.

High viscosity transducer for vibratory viscometer

A viscosity measuring transducer especially useful for process control of fluids. The transducer oscillates an immersed blade sensor in the direction of the plane of the blade in order to maximize generation of shear waves and to minimize generation of compression waves. The transducer includes a bar which penetrates and is secured and peripheral sealed to an isolation plate which serves to protect the oscillation driver and pickup adjacent one end of the bar from the sensor blade to be immersed in a fluid adjacent the other end of the bar. Either the bar is relatively rigid and the isolation plate is relatively compliant, or vice versa. In the former case the isolation plate acts as an intrinsic flexible member of the oscillating system of the transducer; and in both cases the isolation plate constitutes a strong impermeable seal between the fluid and the driver/pickup mechanism. The isolation plate may be corrugated or ribbed to allow vibratory motion in the desired direction (parallel to the sensor blade major surfaces) while resisting movement in the direction perpendicular thereto.

Vibratory viscometer transducer with isolation support for inline

Electronic control circuitry for obtaining precise inline process control data as to viscosity of fluids over a wide viscosity range, with high tolerance of ambient noise and vibration. An electromechanical transducer with an oscillating sensor is immersed in a flowing liquid, with the power required to sustain predetermined oscillation parameters being a measure of viscosity-density product. The gain of a variable gain amplifier which provides positive feedback to sustain oscillation is controlled in response to the integrated error signal output of a comparator which compares a DC value corresponding to the RMS amplitude of mechanical oscillation with a DC reference value. The monitoring of RMS amplitude rather than peak amplitude (as is done by a phase-sensitive sample-and-hold arrangement in the prior art), coupled integration of the error signal, results in a great improvement in immunity to ambient noise and vibration. Other features includes automatic calibration and temperature compensation whereby viscosity at a desired temperature can be determined even though the measurement is made at different temperature.

Control circuitry for viscosity sensors

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Metuchen, NJ, United States of America

John V Fitzgerald