Method and apparatus for fault detection and correction in Coriolis effect mass flowmeters
First Claim
1. A method for detecting abnormal operating conditions in an operating Coriolis effect mass flowmeter comprising the steps of:
- measuring the values of operating parameters of said operating Coriolis effect mass flowmeter, wherein said operating parameters include the vibration frequency of said operating Coriolis effect mass flowmeter and the drive power of said operating Coriolis effect mass flowmeter;
selecting at least one value selected from the group consisting of the measured values of said operating parameters, slopes of said measured values of said operating parameters, and curvatures of said measured values of said operating parameters;
determining that said at least one value has deviated from a nominal value by a predetermined amount indicative of an occurrence of one of said abnormal operating conditions;
generating an output signal indicating said occurrence of said one of said abnormal operating conditions in response to said determination that said at least one value has deviated from a nominal value by said predetermined amount; and
applying said output signal to utilization means for purposes including the correction of said one of said abnormal operating condition in said flowmeter.
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Abstract
Apparatus and methods for detecting and correcting various fault conditions in an operating Coriolis effect mass flowmeter. The apparatus of the present invention receives information from an operating Coriolis mass flowmeter and compares the information to threshold signatures representing various fault conditions. When a fault condition is detected, output signals are applied to inform an operator and to control the mass flow rate through the flowmeter to correct the fault condition. Specifically, the methods of the present invention detect the presence of a crack in the flow tubes and stop the flow of material to prevent release of the material through a cracked flow tubes. Other methods of the present invention detect the void fraction of material flowing through the flow tubes, compute a corrected actual mass flow rate, and control the mass flow rate through the flowmeter to compensate for the effects of the void fraction. Signature information relating to threshold values for measured frequency, drive power, temperature and mass flow of the operating flowmeter as well as the slope and curvature of changes in each measured operating parameter are stored in memory within the fault detection apparatus of the present invention.
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Citations
34 Claims
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1. A method for detecting abnormal operating conditions in an operating Coriolis effect mass flowmeter comprising the steps of:
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measuring the values of operating parameters of said operating Coriolis effect mass flowmeter, wherein said operating parameters include the vibration frequency of said operating Coriolis effect mass flowmeter and the drive power of said operating Coriolis effect mass flowmeter; selecting at least one value selected from the group consisting of the measured values of said operating parameters, slopes of said measured values of said operating parameters, and curvatures of said measured values of said operating parameters; determining that said at least one value has deviated from a nominal value by a predetermined amount indicative of an occurrence of one of said abnormal operating conditions; generating an output signal indicating said occurrence of said one of said abnormal operating conditions in response to said determination that said at least one value has deviated from a nominal value by said predetermined amount; and applying said output signal to utilization means for purposes including the correction of said one of said abnormal operating condition in said flowmeter. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33)
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10. A method for detecting cracks in the flow tubes of an operating Coriolis effect mass flowmeter, said method comprising the steps of:
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generating a signal indicative of the present vibration frequency of said flow tubes of said operating Coriolis effect mass flowmeter; generating a signal indicative of present drive power required to drive said flow tubes of said Coriolis effect mass flowmeter to vibrate at said present vibration frequency; determining that said signal indicative of present vibration frequency is below a vibration frequency nominal value by a predetermined amount; determining that said signal indicative of present drive power is above a drive power nominal value by a predetermined amount; and generating an output signal indicating the presence of a crack in said flow tubes in response to said determination that said present vibration frequency is below said vibration frequency nominal value and in response to said determination that, concurrently, said present drive power is above said drive power nominal value. - View Dependent Claims (11, 12, 13, 14)
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34. An apparatus for detecting a fault condition in an operating Coriolis effect mass flowmeter, said apparatus comprising:
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input means connected to said Coriolis effect mass flowmeter for receiving information including measured values regarding present operating parameters of said Coriolis effect mass flowmeter, wherein said information includes the vibration frequency of said Coriolis effect mass flowmeter and the drive power of said Coriolis effect mass flowmeter; means for selecting at least one value selected from the group consisting of values of present operating parameters of said Coriolis mass flowmeter, slopes of said values of said present operating parameters, and curvatures of said values of said present operating parameters; memory means for storing fault signature information regarding at least one fault condition represented by said present operating parameters; output means for indicating the occurrence of said fault condition in operation of said Coriolis mass flowmeter; and detection means connected to said input means and connected to said output means and connected to said memory means, for comparing said at least one value to said fault signature information to detect the occurrence of said fault condition and to apply a signal to said output means indicating the occurrence of said fault condition.
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Specification