Coriolis Flow Meter Pressure Compensation for Accurate Flow Variables
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Solution Overview
Problem
Existing Coriolis flow meters face measurement errors due to changes in internal pressure, which are not accurately compensated for using external pressure measurements or assumed line pressures, leading to uncertainties and biases in flow and density measurements.
Innovation Solution
A method and system that utilize measurements from pressure sensors at both ends of the flow meter to estimate the internal pressure, applying a pressure compensation factor correlated to the actual internal pressure within the flow tubes, accounting for fluid dynamics and flow direction, to correct flow variables.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If external pressure measurements are used to compensate for internal pressure effects, then device complexity is reduced, but measurement precision deteriorates due to pressure differential uncertainties
Solution Approach 1:
The patent places pressure measurement capability inside the flow meter by installing pressure sensors directly within the flow tubes. This nested arrangement allows internal pressure to be measured at the exact location where it affects the measurement, eliminating the need for external pressure taps and Bernoulli correction calculations, thereby resolving the contradiction between device simplicity and measurement accuracy
Solution Approach 2:
The patent introduces an intermediary pressure sensor system that directly measures internal pressure at the critical location within flow tubes. This intermediary measurement device bridges the gap between the external pressure measurement system and the internal pressure conditions, providing accurate pressure data without requiring complex external measurement and calculation systems
2Ease of manufacture
If pressure taps are installed outside the flow meter, then ease of manufacture is improved, but measurement precision deteriorates due to pressure loss between tap and flow tubes
Solution Approach 1:
The patent integrates pressure sensors directly within the flow tubes during manufacturing, nesting the measurement capability inside the existing flow tube structure. This eliminates the need for separate external pressure taps and the associated pressure loss issues, achieving both manufacturing feasibility and measurement accuracy
Solution Approach 2:
The patent incorporates pressure sensor installation as part of the preliminary manufacturing process, integrating the pressure measurement capability into the flow tubes before they are assembled into the final meter. This preliminary integration ensures accurate internal pressure measurement without requiring post-manufacturing modifications or external tap installations
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach provides more accurate corrections for flow tube stiffness changes, reducing measurement errors and improving the precision of mass flow, volume flow, and density measurements in Coriolis flow meters.
Implementation Method 1
Both flow tubes 130 and 130' are driven by driver 180 in opposite directions in a first out-of-phase bending mode of the flowmeter
Implementation Method 2
Meter electronics 20 receives the left and right velocity signals from velocity pick-off sensors 170L and 170R over leads 102 to compute the mass flow rate, volumetric rate, and/or density information
Implementation Method 3
Coriolis flow meters may be used to measure the mass flow rate, density, volume flow rate, and other information for a process fluid
Data Source
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AI summary
A method for correcting a flow variable (509) based on an inner pressure inside a Coriolis flow meter (202) comprises the steps of receiving a first outside pressure (503) measured with a first pressure sensor (204) located in a first process conduit (208a) positioned on a first end (212a) of the Coriolis flow meter (202), determining a second outside pressure (505) in a second process conduit (208b) positioned on a second end (212b) opposing the first end (212a) of the Coriolis flow meter (202), determining an estimated inner flow meter pressure (507) based on the first outside pressure (503) and the second outside pressure (505), receiving the flow variable (509), and generating a corrected flow variable (512) based on the estimated inner flow meter pressure (507), a pressure compensation factor (510), and the flow variable (509).