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US 7,597,008 B2Granted
Method and apparatus for determining flow pressure using density information
AssigneeMicro Motion, Inc.
InventorsAndrew T. Patten, Karl Benedict Stappert
Life of this patent
Estimating the term…
Abstract
A method and apparatus is disclosed that determines the density (602) of a material flowing through a Coriolis flow meter. The density is used to infer the pressure (608) of the flowing material. The inferred pressure may be used to correct for the secondary pressure effect in the Coriolis flow meter or may be reported to an external device.
Claims16
A method, comprising:
- measuring a density of a material flowing through a Coriolis flow meter (602);
- determining a pressure of the flowing material from the measured density by following the steps of:
- (a) setting a value of compressibility z to 1 in the equation
- P
- =
- ρ
- *
- R
- *
- T
- *
- z
- M
- and calculating a value for a pressure P (604) where T is the temperature, M is a molar weight of the material flowing in the Coriolis flow meter, ρ is the density, and R is a constant;
- (b) using the calculated value of the pressure P to determine a new more accurate value for the compressibility z (606);
- (c) using the new more accurate value for the compressibility z to recalculate a value for the pressure P (608);
- (d) repeating steps (b) and (c) until the value for the pressure has converged to within a predefined limit.
14 more elements
A method, comprising:
- (a) calibrating a density to pressure relationship of a Coriolis flow meter for a material at a low pressure point;
- (b) calibrating a density to pressure relationship of the Coriolis flow meter for the material at a high pressure point;
- (c) storing the two calibrated relationships for the material;
- (d) determining a current pressure for the material based on a measured current density and the two stored calibration relationships;
- (e) determining a compressibility Z for the high and low pressure points (902);
- (f) determining an average molar weight for the high and low pressure points;
- (g) calculating a value for the current pressure;
- (h) determining a new compressibility using the calculated value for the current pressure;
- (i) using the new compressibility to recalculate a new value for the current pressure;
- and
- (j) repeating steps (g)-(i) until the value for the pressure has converged to within a predetermined limit.
8 more elements
Dependencies are inferred from the claim text.