Startup and operational techniques for a digital flowmeter
First Claim
1. A method for operating a digital flowmeter comprising:
- operating the digital flowmeter in a random sequence mode, where the random sequence mode is characterized by a first drive signal that includes randomly-generated values and that causes a vibration of a flowtube;
operating the digital flowmeter in a positive feedback mode, where the positive feedback mode is characterized by a sensor signal that corresponds to the vibration and that is used as a second drive signal for maintaining the vibration; and
operating the digital flowmeter in a digital synthesis mode, where the digital synthesis mode is characterized by a synthesis of a third drive signal for maintaining the vibration.
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Abstract
Startup and operational techniques for a digital flowmeter are described. The techniques select an optimal mode of operation for the digital flowmeter, depending on a current environment of the flowmeter. For example, during a startup operation of the flowmeter, the mode of operation might include a random sequence mode, in which filtered, random frequencies are applied as a drive signal to a flowtube associated with the digital flowmeter. Once the flowtube reaches a resonant mode of vibration, the digital flowmeter may transition to a positive feedback mode, in which a sensor signal representing a motion of the flowtube is fed back to the flowtube as a drive signal, as part of a feedback loop. Once an oscillation of the flowtube is achieved and analyzed, a digital synthesis mode of operation may be implemented, in which the analyzed sensor signals are used to synthesize the drive signal. In either the positive feedback mode or the digital synthesis mode, the digital flowmeter may revert to a previous mode to regain stable and desired oscillation of the flowtube, such as might be required during a recovery operation associated with a disturbance to an operation of the digital flowmeter.
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Citations
43 Claims
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1. A method for operating a digital flowmeter comprising:
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operating the digital flowmeter in a random sequence mode, where the random sequence mode is characterized by a first drive signal that includes randomly-generated values and that causes a vibration of a flowtube;
operating the digital flowmeter in a positive feedback mode, where the positive feedback mode is characterized by a sensor signal that corresponds to the vibration and that is used as a second drive signal for maintaining the vibration; and
operating the digital flowmeter in a digital synthesis mode, where the digital synthesis mode is characterized by a synthesis of a third drive signal for maintaining the vibration. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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22. A digital flowmeter comprising:
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a vibratable flowtube;
a sensor connected to the flowtube and operable to sense information about a motion of the flowtube;
a driver connected to the flowtube and operable to impart energy to the flowtube;
a filter system;
a random-value generator operable to generate random-frequency signals; and
a control and measurement system operable to apply the filter system to the random-frequency signals and supply filtered, random-frequency signals to the driver for application to the flowtube of a first drive signal during a first mode, and further operable to transition the digital flowmeter into a second mode characterized by a second drive signal. - View Dependent Claims (23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36)
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37. A flowmeter comprising:
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a vibratable flowtube;
a sensor connected to the flowtube and operable to sense information about a motion of the flowtube by way of a sensor signal;
a driver connected to the flowtube and operable to impart energy to the flowtube by way of a drive signal; and
a digital transmitter operable to select and implement, from among a plurality of operational modes, an operational mode determined to be best-suited for a current operational environment of the digital flowmeter. - View Dependent Claims (38, 39, 40, 41, 42, 43)
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Specification