Conductive Polymer Reference Connection for Corrosive Mag Flowmeters
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Solution Overview
Problem
Magnetic flowmeters face challenges with corrosive process fluids and high costs due to the use of exotic metals for grounding electrodes, which also lead to potential leaks and limited surface contact, affecting signal quality and electromagnetic immunity.
Innovation Solution
A thermally-stable, chemically-compatible conductive polymer reference connection is used, which serves as both a low-impedance path and a gasket, providing a larger contact area and eliminating leak paths, while reducing the need for exotic metals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If exotic metals are used for grounding electrodes, then electromagnetic immunity is improved, but cost increases and corrosion resistance deteriorates in corrosive environments
Solution Approach 1:
The patent uses a composite structure combining a metal ring (providing electrical conductivity and electromagnetic immunity) with a conductive polymer coating (providing corrosion resistance). This composite material approach allows the grounding electrode to simultaneously achieve electromagnetic immunity from the metal component and corrosion resistance from the polymer coating, resolving the contradiction between these two requirements.
Solution Approach 2:
The conductive polymer coating acts as an intermediary layer between the metal ring and the corrosive process fluid. This intermediate layer protects the metal from direct contact with corrosive substances while maintaining electrical conductivity, thus improving corrosion resistance without sacrificing electromagnetic immunity.
2Reliability
If metal rings are used for grounding connections, then electromagnetic immunity is improved, but leak paths increase and chemical compatibility deteriorates
Solution Approach 1:
The grounding connection uses a composite structure where a metal ring provides electromagnetic immunity and a conductive polymer coating provides chemical compatibility. The polymer coating is specifically selected to be resistant to corrosive process fluids, allowing the metal ring to maintain electromagnetic immunity while the coating ensures chemical compatibility by preventing direct contact between the metal and corrosive substances.
3Reliability
If grounding electrodes are spaced from electrodes, then electromagnetic immunity is improved, but contact area decreases affecting signal quality
Solution Approach 1:
The patent applies local quality by providing different functional zones: the conductive polymer reference connection provides a localized low-impedance path for electromagnetic immunity near the electrodes, while the grounding connection at the coupling point provides chemical compatibility. This localized functional differentiation allows electromagnetic immunity to be improved without compromising signal quality, as each zone performs its specific function optimally.
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 conductive polymer reference connection enhances signal quality, improves electromagnetic immunity, and prevents leaks, offering a cost-effective solution for measuring flow rates in corrosive environments.
Implementation Method 1
The conductive polymer reference connection is spaced from the pair of electrodes and configured to contact the process fluid. The conductive polymer reference connection is coupled to the flowmeter electronics.
Implementation Method 2
Magnetic flowmeters (or mag meters) measure flow by Faraday induction, an electromagnetic effect. The magnetic flowmeter energizes one or more coils which generate a magnetic field across a section of a flowtube assembly. The magnetic field induces an electromotive force (EMF) across the flow of conductive process fluid through the flowtube assembly.
Data Source
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AI summary
An electromagnetic flowmeter assembly (100) is provided. The assembly (100) includes a magnetic flowmeter (116) configured to couple to a process pipe (118) at a coupling point and measure a flowrate of a flow of process fluid. The assembly (100) includes a conductive polymer reference connection (112) configured to contact the process fluid and provide an electrical connection to magnetic flowmeter electronics.