Slug Flow Detection in Field Devices for Accurate Density Measurement
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Solution Overview
Problem
Field devices, such as Coriolis mass flow rate meters, face measurement errors due to slug flows, which mix air bubbles into the measured fluid, leading to inaccurate density values, especially when the error occurs before detection.
Innovation Solution
A field device and management system that includes a slug flow detector and a controller to hold a predetermined average value of measured values from before the slug flow detection, ensuring accurate measurements by avoiding immediate pre-detection values affected by slug flows.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If a density value from immediately before detection of slug flow is used, then the response time is reduced, but the measurement precision deteriorates because the slug flow has already occurred and affected the measurement
Solution Approach 1:
The system performs preliminary actions by detecting slug flow occurrence and holding the measured value from before the slug flow affected the measurement. The controller detects when slug flow occurs and proactively holds the last valid density value before the slug flow impact, rather than waiting for the measurement to become corrupted and then correcting it.
Solution Approach 2:
The invention introduces an intermediary mechanism (the holding function in the controller) that mediates between the raw measured values and the output density value. When slug flow is detected, this intermediary holds the previous valid value, acting as a buffer that prevents the corrupted measurement from being output while maintaining system responsiveness.
2Reliability
If conventional slug flow detection is implemented, then slug flow events are identified, but the measurement accuracy deteriorates because the detection occurs after the slug flow has already affected the measurement
Solution Approach 1:
The system implements feedback by continuously monitoring measured values and comparing them against expected ranges to detect slug flow occurrence. When a deviation indicating slug flow is detected, the system responds by holding the previous valid measured value, creating a closed-loop control that maintains measurement accuracy despite slug flow events.
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 system enables more accurate measurement of fluid density even during slug flows by using held values based on previous measurements, reducing errors and ensuring reliable data during slug flow occurrences.
Implementation Method 1
a slug flow detector configured to detect an occurrence of a slug flow
Implementation Method 2
a controller configured to hold a hold value of the measured value if the occurrence of the slug flow is detected by the slug flow detector, the hold value being a value based on at least one measured value in a predetermined period from a predetermined time before a time at which the slug flow has been detected
Data Source
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AI summary
A field device configured to measure a state amount of a fluid as a measured value, the field device includes a slug flow detector configured to detect an occurrence of a slug flow, and a controller configured to hold a hold value of the measured value if the occurrence of the slug flow is detected by the slug flow detector, the hold value being a value based on at least one measured value in a predetermined period from a predetermined time before a time at which the slug flow has been detected.