Flowmeter Sensor Diagnosis Using Dual Active Thermal Control
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Solution Overview
Problem
Flowmeters in industrial environments face accuracy issues due to uncontrolled heat transfer mechanisms, particularly in dusty, humid, or oily conditions where coatings form on sensors, leading to reduced heating power needs and incorrect flow rate measurements, and existing diagnosis methods are either unreliable or require significant downtime.
Innovation Solution
A method involving thermally coupling two sensor units to a fluid, actively heating or cooling them to different temperatures, and determining independent heat transfer-related quantities to diagnose sensor conditions without interrupting flow rate measurement, thereby avoiding dead times and ensuring reliable diagnosis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the heated sensor is switched with the unheated sensor for diagnosis, then the coating effect can be detected, but the flow rate measurement cannot be performed during the switching and cooling period, creating dead time
Solution Approach 1:
The unheated sensor is pre-heated to the diagnostic temperature T2 before the heated sensor is switched off. This preliminary action ensures that when the switching occurs, both sensors are already at the required diagnostic temperature, eliminating the cooling wait time and allowing immediate flow rate measurement and diagnosis to proceed without dead time.
Solution Approach 2:
The diagnostic measurement process continues without interruption by having both sensors capable of operating at temperature T2 simultaneously. The unheated sensor is prepared in advance to take over diagnostic functions immediately when needed, ensuring continuous useful action without pauses or dead time in the flow rate measurement and diagnosis process.
2Reliability
If the heated sensor is switched off and cooled to fluid temperature for diagnosis, then sensor coating can be detected, but flow rate measurement is impossible during this period
Solution Approach 1:
The unheated sensor is pre-heated to temperature T2 before switching is required. This preliminary preparation allows the sensor to immediately assume diagnostic duties when the originally heated sensor needs to be switched off, maintaining continuous productivity and eliminating measurement gaps.
Solution Approach 2:
A second sensor (the unheated sensor) is used as a copy or backup of the heated sensor. This redundant sensor can be pre-prepared and switched into the diagnostic role without interrupting the overall measurement process, allowing diagnosis to proceed while maintaining continuous flow rate measurement capability through the other sensor.
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 allows for simultaneous measurement of flow rates and sensor diagnosis, reducing downtime and improving measurement accuracy by detecting coating effects on sensors, ensuring continuous operation and cost-effective maintenance.
Implementation Method 1
The second temperature sensor can be cooled by forced convection which depends on the velocity of the fluid passing the sensor
Implementation Method 2
A coating may, for example, build up during operation in dusty, humid, oily, or sooty environments. Coatings can have a lower heat conductivity as compared to the materials of which the sensors are made
Implementation Method 3
actively heating or cooling the first sensor unit by applying power PM1 to the first sensor unit such that the temperature TM1 of the first sensor unit is different from the temperature TM0 of the fluid
Data Source
AI summary
A method and an apparatus for diagnosis of a flowmeter are disclosed. The method includes thermally coupling a first sensor unit of the flowmeter to a fluid and thermally coupling a second sensor unit of the flowmeter to the fluid. The method also includes actively heating or cooling the first sensor unit by applying power to the first sensor unit such that its temperature is different from the temperature of the fluid, and simultaneously actively heating or cooling the second sensor unit by applying power to the second sensor unit such that its temperature is different from the temperature of the fluid, and typically from the temperature of the first sensor. The method can include determining a temperature TM0 of the fluid, and determining at least two independent quantities related to the heat transfer of the sensor units, each of the at least two independent heat transfer related quantities being determined from at least one element selected from the group including TM0, TM1, TM2, PM1, and PM2, and determining a diagnosis result by setting into relation the at least two independent heat transfer related quantities.