US 7,480,576 B2 · Compensating for frequency change in flowmeters

Abstract

Motion is induced in a conduit that contains a fluid. The motion is induced such that the conduit oscillates in a first mode of vibration and a second mode of vibration. The first mode of vibration has a corresponding first frequency of vibration and the second mode of vibration has a corresponding second frequency of vibration. At least one of the first frequency of vibration or the second frequency of vibration is determined. A phase difference between the motion of the conduit at a first point of the conduit and the motion of the conduit at a second point of the conduit is determined. A quantity based on the phase difference and the determined frequency is determined. The quality includes a ratio between the first frequency during a zero-flow condition and the second frequency during the zero-flow condition. A property of the fluid is determined based on the quantity.

Claims24

Dependent claims

A method comprising:

inducing motion in a conduit such that the conduit oscillates in a first mode of vibration and a second mode of vibration, the first mode of vibration having a corresponding first frequency of vibration and the second mode of vibration having a corresponding second frequency of vibration, wherein the conduit contains a fluid;
determining at least one of the first frequency of vibration or the second frequency of vibration;
determining a phase difference between the motion of the conduit at a first point of the conduit and the motion of the conduit at a second point of the conduit;
determining a quantity based on the phase difference and the determined frequency, wherein the quantity includes a ratio between the first frequency during a zero-flow condition and the second frequency during the zero-flow condition;
and
determining a property of the fluid based on the quantity.

3 more elements

A flowmeter comprising:

a vibratable flowtube, the flowtube containing a fluid;
a driver connected to the flowtube and configured to impart motion to the flowtube such that the conduit oscillates in a first mode of vibration and a second mode of vibration, the first mode of vibration having a corresponding first frequency of vibration and the second mode of vibration having a corresponding second frequency of vibration;
a sensor connected to the flowtube and configured to sense the motion of the flowtube and generate a sensor signal;
and
a controller to receive the sensor signal and configured to:
determine at least one of the first frequency of vibration or the second frequency of vibration;
determine a phase difference between the motion of the conduit at a first point of the conduit and the motion of the conduit at a second point of the conduit;
determine a quantity based on the phase difference and the determined frequency, wherein the quantity includes a ratio between the first frequency during a zero-flow condition and the second frequency during the zero-flow condition;
and
determine a property of the fluid based on the quantity.

7 more elements

A flowmeter transmitter comprising:

at least one processing device;
and
a storage device, the storage device storing instructions for causing the at least one processing device to:
induce motion in a conduit such that the conduit oscillates in a first mode of vibration and a second mode of vibration, the first mode of vibration having a corresponding first frequency of vibration and the second mode of vibration having a corresponding second frequency of vibration;
determine at least one of the first frequency of vibration or the second frequency of vibration;
determine a phase difference between the motion of the conduit at a first point of the conduit and the motion of the conduit at a second point of the conduit;
determine a quantity based on the phase difference and the determined frequency, wherein the quantity includes a ratio between the first frequency during a zero-flow condition and the second frequency during the zero-flow condition;
and
determine a property of the fluid based on the quantity.

6 more elements

Dependencies are inferred from the claim text.

Compensating for frequency change in flowmeters

Life of this patent

Compensating for frequency change in flowmeters

Life of this patent

Abstract

Claims24