Method and apparatus for measuring pressure in a coriolis mass flowmeter
US5734112A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 14, 1996 |
| Grant date | Mar 31, 1998 |
| Priority date | — |
| Expiry date | Aug 14, 2016 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01F1/8477
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A method for determining pressure in an operating Coriolis effect mass flowmeter. The Coriolis flowmeter flow tubes are vibrated in both a bending mode (as is normal for measuring mass flow rate) and in a twisting mode. The ratio of the fundamental frequencies at which the flow tubes vibrate in each of the two vibration modes is proportional to the pressure within the flow tubes. In the preferred embodiment, a sum/difference method initially isolates the superposed sinusoids representing the fundamental frequencies of the two vibrational modes. Fast conjugate gradient (FCG) digital filters are then used to rapidly estimate the fundamental frequencies in each of the two vibration modes. The estimated frequencies are then used by filter chains including digital notch and band pass filters as well as recursive maximum likelihood (RML) digital filter techniques to enhance the bending mode and twisting mode fundamental frequency estimates. The enhanced bending mode and twisting mode frequency estimates are used to determine the pressure within the flow tubes as a function of the ratio of the two frequencies as well as to center the notch and band pass filter chains used to enhance the b…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.