Claims
- 1. A method of calibrating a flowmeter comprising:
determining a plurality of calibration values, the calibration values corresponding to measurements of material in a flowtube, the flowtube being associated with the flowmeter; associating each of the calibration values with one of a plurality of operational parameters of the flowmeter, each of the operational parameters being present during the determining of its corresponding calibration value; and storing the calibration values in association with their respective operational parameters.
- 2. The method of claim 1 wherein determining the plurality of calibration values comprises determining a plurality of zero-flow calibration values corresponding to the measurements, where the measurements include mass flow measurements erroneously indicated by the flowmeter during a time of substantially zero mass flow through the flowtube.
- 3. The method of claim 1 further comprising:
determining a current operational parameter of the flowmeter; and determining a current calibration value for use during an obtaining of a mass flow measurement, based on the current operational parameter.
- 4. The method of claim 3 wherein determining the current operational parameter comprises determining a density of the material in the flowtube.
- 5. The method of claim 4 wherein determining the current calibration value of the flowmeter comprises measuring a current density of a current material in the flowtube.
- 6. The method of claim 4 wherein associating each of the calibration values with one of the plurality of operational parameters comprises associating a first calibration value with a range of densities.
- 7. The method of claim 6 wherein determining the current calibration value comprises:
measuring a current density of a current material in the flowtube; determining that the current density falls within the range of densities; and selecting the first calibration value.
- 8. The method of claim 4 wherein associating each of the calibration values with one of the plurality of operational parameters comprises using a mathematical relationship between the calibration values and the plurality of operational parameters.
- 9. The method of claim 8 wherein determining the current calibration value comprises:
measuring a current density of a current material in the flowtube; using the current density in conjunction with the mathematical relationship to determine a current calibration value; and selecting the current calibration value.
- 10. The method of claim 3 wherein determining the current operational parameter comprises determining a configuration of flow elements associated with the flowtube.
- 11. The method of claim 10 wherein determining the current calibration value comprises accepting an input from a user, the input identifying a current configuration of flow elements.
- 12. The method of claim 10 wherein determining the current calibration value comprises:
measuring a first density of a first material in the flowtube; accessing a correlation between the first density and a first configuration of flow elements; and selecting a first calibration value corresponding to the first configuration.
- 13. The method of claim 3 wherein determining the current operational parameter comprises determining a gas void fraction of the material in the flowtube.
- 14. The method of claim 13 wherein determining the current calibration value comprises:
receiving an input of the gas void fraction from a gas void fraction measurement system; and selecting the current calibration value from a pre-determined list of associated calibration values and gas void fractions.
- 15. A calibration system comprising:
a measurement system operable to output measurements of material in a flowtube, where the flowtube is associated with a flowmeter; a calibration system operable to determine calibration values, each based on a corresponding measurement output by the measurement system; and a memory operable to store each of the calibration values in conjunction with an operational parameter associated with an operation of the flowmeter at a time of the corresponding measurement.
- 16. The system of claim 15 wherein the calibration system is operable to select a calibration value from the memory, based on a current operational parameter associated with the flowmeter.
- 17. The system of claim 15 wherein the measurement includes a mass flow rate of the material, and further wherein the calibration values include zero calibration values corresponding to erroneously-detected mass flow measurements of the material during a time of substantially zero flow.
- 18. The system of claim 15 wherein the operational parameter includes a density of the material.
- 19. The system of claim 18 wherein the calibration system is operable to select a current calibration value based on a current density of material in the flowtube, as measured by the measurement system.
- 20. The system of claim 19 wherein the calibration system is operable to select the current calibration value by associating the current density with a pre-selected range of densities that is stored in the memory in association with the current calibration value.
- 21. The system of claim 19 wherein the calibration system is operable to select the current calibration value, based on the current density and a mathematical relationship between the calibration values and their corresponding operational parameters.
- 22. The system of claim 15 wherein the operational parameter includes a configuration of flow elements associated with the flowtube.
- 23. The system of claim 22 wherein the calibration system is operable to accept a current configuration input by an operator, and to select a current calibration value based on the current configuration.
- 24. The system of claim 22 wherein the calibration system is operable to select a current calibration value by determining a current configuration based on a currently-measured density that was previously associated with the current configuration.
- 25. The system of claim 15 wherein the operational parameter includes a gas void fraction of flow elements within the flowtube.
- 26. The system of claim 25 wherein the calibration system is operable to receive a current gas void fraction from a gas void fraction measurement system, and further operable to select a corresponding current calibration value from the memory.
- 27. The system of claim 15 wherein the measurement system, the calibration system, and the memory are integrated with the flowmeter.
- 28. A method of operating a flowmeter comprising:
determining an operational parameter associated with the flowmeter; determining a zero-flow calibration value based on the operational parameter, based on a plurality of previously-determined zero-flow calibration values; taking a measurement of a property of a material within a flowtube associated with the flowmeter, using the flowmeter; and adjusting the measurement using the zero-flow calibration value.
- 29. The method of claim 28 wherein determining the operational parameter includes determining a configuration of flow elements associated with the flowtube.
- 30. The method of claim 29 wherein determining the zero-flow calibration value comprises selecting the zero-flow calibration value from among the previously-determined zero-flow calibration values as being the zero-flow calibration value that corresponds to one of a set of configurations, where each of the set of configurations existed at a time when its corresponding zero-flow calibration value was previously determined.
- 31. The method of claim 29 wherein determining the operational parameter comprises accepting a selection of the configuration from a predetermined set of configurations.
- 32. The method of claim 29 wherein determining the operational parameter comprises:
measuring a density of the material; and associating the density with a first configuration.
- 33. The method of claim 28 wherein the operational parameter includes a density of the material in the flowtube.
- 34. The method of claim 33 wherein determining the zero-flow calibration value comprises:
associating the density with a range of densities; and selecting the zero-flow calibration value from among the plurality of previously-determined zero-flow calibration values, based on a pre-determined relationship between the range of densities and the zero-flow calibration value.
- 35. The method of claim 33 wherein determining the zero-flow calibration value comprises inputting the density into a mathematical relationship derived from a relationship between the previously-determined zero-flow calibration values and corresponding density measurements.
- 36. The method of claim 28 wherein determining the zero-flow calibration value comprises selecting the zero-flow calibration value from among the plurality of previously-determined zero-flow calibration values, based on a pre-determined relationship between the operational parameter and the zero-flow calibration value.
- 37. The method of claim 28 wherein determining the operational parameter includes determining a gas void fraction of the material in the flowtube.
- 38. The method of claim 37 wherein determining the gas void fraction comprises receiving a current gas void fraction from a gas void fraction measurement system, and further wherein determining the zero-flow calibration value comprises selecting a current zero-flow calibration value previously associated with the current gas void fraction measurement.
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to U.S. Provisional Application Serial No. 60/460,817, filed on Apr. 8, 2003, and titled “FLOWMETER ZEROING TECHNIQUES,” which is incorporated by reference.
Provisional Applications (1)
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Number |
Date |
Country |
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60460817 |
Apr 2003 |
US |