Vibratory Flowmeter Confidence Determination for Multiphase Flows
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Solution Overview
Problem
Coriolis mass flowmeters face significant accuracy degradation when measuring multiphase flows due to fluid decoupling caused by entrained gas and solids, leading to under-reported flow and density characteristics, and existing methods struggle to effectively compensate for these errors, especially in applications with variable gas behavior.
Innovation Solution
A method and device for a vibratory flowmeter that measures entrained gas and determines a measurement confidence level by analyzing drive gain thresholds, gas slug severity, flow rates, and hold value standard deviations to provide a confidence indicator for improving measurement accuracy in multiphase flows.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a Coriolis flowmeter is used to measure aerated fluids or multiphase flows, then the flowmeter can potentially be used in a wider range of applications, but the accuracy of the meter is significantly degraded due to fluid decoupling caused by entrained gas and solids
Solution Approach 1:
The patent segments the measurement process by identifying distinct flow conditions (single-phase vs. multiphase) and applying different measurement and compensation strategies for each. The system divides the fluid column into discrete elements and tracks individual bubble behaviors to calculate decoupling effects separately, then combines these segment-level analyses into overall compensation.
Solution Approach 2:
The patent changes key parameters including drive gain amplitude, vibration frequency, and measurement timing based on detected flow conditions. By adjusting these parameters dynamically according to the presence and characteristics of entrained gas and solids, the system maintains measurement accuracy across varying multiphase conditions while preserving the ability to handle diverse applications.
2Measurement precision
If the vibration amplitude of the flow conduit is increased to improve signal detection, then the measurement sensitivity is improved, but the fluid decoupling effect is exacerbated causing larger measurement errors
Solution Approach 1:
The patent implements feedback by continuously monitoring vibration amplitude, drive gain, and flow characteristics to detect the presence and severity of fluid decoupling. This feedback information is used to dynamically adjust the drive gain and vibration amplitude in real-time, reducing the amplitude when decoupling is detected to minimize measurement errors while maintaining adequate signal detection.
Solution Approach 2:
The system transitions from static vibration amplitude operation to dynamic adjustment of vibration characteristics. By making the vibration amplitude and frequency adjustable and adaptive based on real-time flow conditions, the system can optimize detection sensitivity while preventing excessive decoupling effects that would occur with fixed high-amplitude operation.
3Measurement precision
If hold values from single-phase flow periods are used to compensate for multiphase flow errors, then measurement accuracy is improved during multiphase conditions, but the system requires periods of single-phase flow which may not always be available
Solution Approach 1:
The patent applies preliminary action by capturing and storing hold values during single-phase flow periods before multiphase conditions occur. These pre-captured reference values are then used for compensation during subsequent multiphase flow periods, allowing the system to prepare compensation data in advance when optimal measurement conditions exist.
Solution Approach 2:
The system introduces an intermediary computational model that can estimate flow characteristics and generate virtual hold values even when actual single-phase flow periods are unavailable. This intermediary mechanism uses the captured bubble behavior data and decoupling models to synthesize compensation information, bridging the gap when direct single-phase reference measurements cannot be obtained.
4Use of energy by moving object
If the drive gain is increased to maintain vibration amplitude in multiphase flows, then the vibration signal strength is maintained, but the measurement errors due to gas slugs and entrained solids are amplified
Solution Approach 1:
The patent implements periodic measurement cycles that alternate between high drive gain periods (for adequate signal strength) and low drive gain periods (for accurate bubble behavior observation). By periodically switching between these modes and using data from both, the system maintains sufficient vibration signal while capturing accurate decoupling characteristics for compensation.
Solution Approach 2:
The system dynamically changes the drive gain parameter based on real-time detection of gas slug severity and entrained solids concentration. When these harmful factors are detected at high levels, the drive gain is reduced to minimize their amplifying effect on measurement errors, while maintaining adequate vibration amplitude through adjusted measurement timing and signal processing.
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
The solution enhances measurement confidence and accuracy in multiphase flows by adjusting drive gain and using hold values from low-gas periods, effectively mitigating errors caused by entrained gas and solids, allowing for more reliable flowmeter performance and decision-making in critical applications.
Implementation Method 1
Excitation is typically provided by a driver, e.g., an electromechanical device, such as a voice coil-type actuator, that perturbs the conduit in a periodic fashion.
Implementation Method 2
Vibrating conduit sensors, such as Coriolis mass flowmeters and vibrating densitometers, typically operate by detecting motion of a vibrating conduit that contains a flowing material.
Implementation Method 3
The relative motion of the gas bubbles with respect to the liquid is driven by a buoyant force that is similar to the force that causes bubbles to rise to the surface under the influence of gravity.
Implementation Method 4
Because the dense fluid has more mass than the light bubbles, the bubbles have greater acceleration than the fluid in the direction of the tube acceleration. Due to the greater acceleration of the bubbles, on each oscillation of the flow conduit, the bubbles move further than the flow conduit. This is the basis of the decoupling problem.
Data Source
AI summary
A method for operating a vibratory flowmeter (5) is provided. The method includes placing a process fluid in the vibratory meter (5) and measuring entrained gas in the process fluid. A measurement confidence level is determined for at least one operating variable.