Coriolis Flowmeter Wet Gas Compensation for Accurate Mass Flow
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Solution Overview
Problem
Coriolis flowmeters experience reduced accuracy in measuring multi-phase flows, particularly in wet gas conditions, due to damping of sensor tube vibration and decoupling of droplets, leading to measurement errors and the inability to augment drive energy beyond a certain limit.
Innovation Solution
A flowmeter system that includes a flow tube, pickoff sensors, and meter electronics to derive unremediated density and mass flow, calculate a density ratio, and apply wet gas coefficients to determine dry gas mass flow rate, using extended drive gain and flow variables like pressure and water cut to improve measurement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Coriolis flowmeter is used to measure wet gas flows, then mass flow and density can be measured simultaneously, but measurement accuracy is degraded due to multi-phase flow effects
Solution Approach 1:
The patent applies parameter changes by utilizing multiple vibration modes (not just the fundamental mode) and processing signals from multiple pickoff sensors at different locations. By analyzing parameters such as amplitude ratios, phase differences, and frequency responses across different modes, the system compensates for multi-phase flow effects and improves measurement accuracy in wet gas conditions.
2Reliability
If drive energy is increased to compensate for diminished vibration amplitude in multi-phase flow, then vibration amplitude can be maintained, but drive energy is limited by maximum ceiling for safety reasons
Solution Approach 1:
The patent employs dynamics by continuously adapting the drive signal based on real-time feedback from multiple pickoff sensors. The system dynamically adjusts excitation parameters including frequency, amplitude, and phase for different vibration modes to maintain reliable measurements without requiring excessive drive energy, thus operating safely within energy limits while compensating for multi-phase flow damping effects.
3Measurement precision
If conventional Coriolis meter is used for single-phase flows, then high accuracy is achieved, but it cannot accurately measure multi-phase flows with entrained gas or liquid
Solution Approach 1:
The patent implements universality by designing a flowmeter system that can accurately measure both single-phase and multi-phase flows. This is achieved through multi-mode vibration excitation, multiple pickoff sensors positioned at different locations, and sophisticated signal processing algorithms that can distinguish between single-phase and multi-phase flow conditions and apply appropriate compensation, making the device universally applicable to various flow types.
4Measurement precision
If multiple pickoff sensors are used to measure vibrational response, then more measurement data is available, but device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the flowtube into multiple measurement zones with pickoff sensors positioned at different locations. Each sensor segment provides localized vibrational response data, and the system processes these segmented measurements independently before combining them through signal processing algorithms to achieve improved overall measurement precision while managing device complexity through modular sensor placement.
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
Enhances measurement accuracy in multi-phase flows by compensating for decoupling errors, allowing real-time monitoring of wellhead performance and reducing the need for separate phase measurements, thus lowering costs and complexity.
Implementation Method 1
vibrating at least one flow tube in a drive mode vibration with the at least one driver
Implementation Method 2
receiving a sensor signal based on a vibrational response to the drive mode vibration from the at least one pickoff sensor
Implementation Method 3
Mass flow rate may be determined by measuring time delay or phase differences between motions at the transducer locations
Data Source
AI summary
A method for improving flowmeter accuracy is provided. The flowmeter comprises at least one flow tube, at least one pickoff sensor attached to the flow tube, at least one driver attached to the flow tube, and meter electronics in communication with the at least one pickoff sensor and driver. The method comprises the steps of vibrating at least one flow tube in a drive mode vibration with the at least one driver and receiving a sensor signal based on a vibrational response to the drive mode vibration from the at least one pickoff sensor. An unremediated density is derived with the flowmeter. An unremediated mass flow is derived with the flowmeter. An extended drive gain is derived with the flowmeter. At least one flow variable is received. A density ratio is calculated. A plurality of wet gas coefficients is provided. A dry gas mass flow rate is calculated with the density ratio and at least one of the plurality of wet gas coefficients.