Measuring and testing – Volume or rate of flow – Mass flow by imparting angular or transverse momentum to the...
Patent
1989-02-23
1991-07-02
Goldstein, Herbert
Measuring and testing
Volume or rate of flow
Mass flow by imparting angular or transverse momentum to the...
G01F 184
Patent
active
050276620
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to Coriolis mass flow rate meters that include one or more flow conduits which are driven to oscillate at the resonant frequency associated with the combined mass of the flow conduit and the fluid flowing therethrough. The drive frequency is maintained at resonance by a feedback system, which detects a change in the resonant behavior of the fluid-filled conduit as a result of the fluid mass change due to the change in fluid density. The flow conduits used in these Coriolis mass flow rate meters are mounted so they can oscillate at the resonant frequency associated with the oscillation axis about which externally applied forces act to oscillate each flow conduit. The flow conduit also deforms about another axis which is associated with deflections of each flow conduit caused by Coriolis forces arising from the combination of the driven oscillation and flow of fluids through the flow conduit. The axis associated with Coriolis deflections is substantially transverse to the oscillation axis. According to the present invention greater accuracy of measurement at high flow rates is obtained in flow meter designs which employ signal processing which includes a non-linear phase angle difference relationship between the signals of motion sensors mounted on or adjacent the flow conduit. The present invention also accounts for asymmetries in flow conduit deflections and for viscous damping in the flow conduits due to properties of the flow conduit materials and the flow of fluids through the conduits.
BACKGROUND ART
In the art of measuring mass flow rates of flowing substances it is known that flowing a fluid through an oscillating flow conduit induces Coriolis forces to act on the conduit. It is also known that the magnitudes of such Coriolis forces are related to both the mass flow rate of the fluid passing through the conduit and the angular velocity at which the conduit is oscillated.
One of the major technical problems previously associated with efforts to design and make Coriolis mass flow rate instruments was the necessity either to measure accurately or control precisely the angular velocity of an oscillated flow conduit so that the mass flow rate of the fluid flowing through the flow conduits could be calculated using measurements of effects caused by Coriolis forces. Even if the angular velocity of a flow conduit could be accurately determined or controlled, precise measurement of the magnitude of effects caused by Coriolis forces was another severe technical problem. This problem arises in part because the magnitudes of generated Coriolis forces are very small in comparison to other forces such as inertia and damping, therefore resulting Coriolis force-induced effects are minute. Further, because of the small magnitude of the Coriolis forces, effects resulting from external sources such as vibrations induced, for example, by neighboring machinery or pressure surges in fluid lines, may cause erroneous determinations of mass flow rates. Such error sources as discontinuities in the flow tube may even completely mask the effects caused by generated Coriolis forces rendering a flow meter useless.
A mechanical structure and measurement technique which, among other advantages: (a) avoids the need to measure or control the magnitude of the angular velocity of a Coriolis mass flow rate instrument's oscillating flow conduit; (b) concurrently provides requisite sensitivity and accuracy for the measurement of effects caused by Coriolis forces; and, (c) minimizes susceptibility to errors resulting from external vibration sources, is taught in U.S. Pat. Nos. Re 31,450, entitled "Method and Structure for Flow Measurement" and issued Nov. 29, 1983; U.S. Pat. No. 4,422,338 entitled "Method and Apparatus for Mass Flow Measurement" and issued Dec. 27, 1983; and U.S. Pat. No. 4,491,025 entitled "Parallel Path Coriolis Mass Flow Rate Meter" and issued Jan. 1, 1985. The mechanical arrangements disclosed in these patents incorporate flow conduits having no pressure sensitive joint
REFERENCES:
patent: Re31450 (1983-11-01), Smith
patent: 916780 (1986-10-01), Ruesch
patent: 916973 (1986-10-01), Ruesch
patent: 3021481 (1962-02-01), Kalmus et al.
patent: 3527103 (1970-09-01), Hale et al.
patent: 3579104 (1971-05-01), Pignard et al.
patent: 3641817 (1972-02-01), Dory
patent: 4095469 (1978-06-01), Yamada et al.
patent: 4127028 (1978-11-01), Cox et al.
patent: 4246497 (1981-01-01), Lawson et al.
patent: 4247819 (1981-01-01), Shimada et al.
patent: 4422338 (1983-12-01), Smith
patent: 4483202 (1984-11-01), Ogura et al.
patent: 4488108 (1984-12-01), Treise et al.
patent: 4491009 (1985-01-01), Ruesch
patent: 4491025 (1985-01-01), Smith et al.
patent: 4559833 (1985-12-01), Sipin
patent: 4581595 (1986-04-01), Silagi
patent: 4622858 (1986-11-01), Mizerak
patent: 4660421 (1987-04-01), Dahlin et al.
patent: 4675614 (1987-06-01), Gehrke
Furness, Dr. R. A.; "Coriolis Mass Meter Experience", Preprint of Presentation given at Stavenger, Norway for North Sea Meter Workshop; (Oct. 13, 1987).
Walewski, Kendrick; "Position Detection Device Using Amplitude Modulation"; IBM Technical Disclosure Bulletin; vol. 14, No. 7, (Dec. 1971).
Dranetz Engineering Laboratory; "Applications Handbook of Precision Phase Measurennt"; (1975).
Hilton and Scott; "Time Interval Measurements with the --hp-- Electronic Counter"; Hewlett-Packard Journal; (Sep.-Oct. 1953).
Sipin, "Vibratory Sewer Flow Meter"; Prepared for the Environmental Protection Agency; Contract 14-12-907; (Mar. 15, 1972).
Heydeman; "On the Precise Measurment of Phase Angles"; Acustica; vol. 13 (1963).
McKinney; "Digitized Low-Frequency Phasemeter Assembled from Logic Modules"; Journal of Research of the National Bureau of Standards; vol. 71C, No. 3; (Jul.-Sep. 1967).
Kalotay Paul Z.
Titlow Joseph D.
Goldstein Herbert
Micro Motion Inc.
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