Method for operating a coriolis mass flowmeter

Patent metadata

Field	Value
Publication number	US-9513150-B2
Application number	US-201514963567-A
Country	US
Kind code	B2
Filing date	Dec 9, 2015
Priority date	Jan 15, 2015
Publication date	Dec 6, 2016
Grant date	Dec 6, 2016

Abstract

A method for operating a Coriolis mass flowmeter that has at least one measuring tube, at least one oscillation generator, at least two oscillation sensors and at least one evaluation unit, wherein the oscillation sensors and/or oscillation generator has at least one coil, wherein the oscillation generator excites the measuring tube to oscillation, wherein the oscillation sensors detect the oscillations of the measuring tube, wherein the temperature of the measuring tube is determined and wherein the evaluation unit processes the detected oscillation signals and determines state variables of the Coriolis mass flowmeter. The electric impedance of the coil of the oscillation generator and/or the electric impedance of at least one coil of the oscillation sensors is determined and the evaluation unit calculates at least one temperature-dependent state variable which is based on the temperature of the measuring tube and which is corrected based upon the determined impedance of the coil.

First claim

What is claimed is:

1. Method for operating a Coriolis mass flowmeter having at least one measuring tube, at least one oscillation generator, at least two oscillation sensors and at least one evaluation unit, wherein at least one the oscillation sensors and the oscillation generator include at least one permanent magnet and at least one coil, comprising the steps of:
using the oscillation generator to excite the measuring tube to oscillation,
using the oscillation sensors to detect oscillations of the measuring tube,
determining the temperature of the measuring tube and
using the evaluation unit to process the detected oscillation signals and determine state variables of the Coriolis mass flowmeter,
wherein the electric impedance of at least one of the coil of the oscillation generator and the at least one coil of the oscillation sensors is determined and
wherein the evaluation unit calculates at least one temperature-dependent state variable D, wherein the temperature-dependent state variable D is corrected based on the determined impedance of the coil.

2. Method according to claim 1 , wherein the correction of the temperature-dependent state variable D is performed based on a temperature coefficient of the impedance of the coil.

3. Method according to claim 1 , wherein a reference value D ref for the temperature-dependent state variable D is determined in a running process before the Coriolis mass flowmeter is initialized.

4. Method according to claim 3 , wherein the reference value D ref of the temperature-dependent state variable D is compared to a measured value D mess of the temperature-dependent state variable D determined during operation.

5. Method according to claim 4 , wherein a signal is issued by the evaluation unit when a pre-defined deviation E of the reference value D ref from the measured value D mess of the temperature-dependent state variable D determined during operation is exceeded.

6. Method according to claim 4 , wherein at least one the reference value D ref and the measured value D mess of the temperature-dependent state variable D is determined using the relation:
D=α 1 +α 2 ΔT+α 3 ΔR drv

wherein R drv is the electric impedance of the coil, T is the measuring tube temperature, and coefficients α 1 to α 3 are empirically determined parameters for the specific Coriolis mass flowmeter.

7. Method according claim 1 , wherein the temperature-dependent state variable D is calculated in dependence on the stiffness of the measuring tube.

8. Method according claim 1 , wherein the temperature-dependent state variable D is calculated in dependence on the damping of the measuring tube.

9. Method according claim 1 , wherein the temperature-dependent state variable D is calculated in dependence on the mass of the measuring tube.

Assignees

• Krohne Ag

Inventors

• Wang Tao

Classifications

• G01F15/022

  using electrical means · CPC title

• G01F1/8495 Primary

  with multiple measuring conduits · CPC title

• G01F1/8436 Primary

  signal processing · CPC title

• G01F15/02

  Compensating or correcting for variations in pressure, density or temperature · CPC title

• G01F1/84

  Coriolis or gyroscopic mass flowmeters · CPC title