Bowl-Shaped Sensor Membrane for High-Pressure Steam
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Solution Overview
Problem
Conventional vortex flow measuring systems have limited pressure resistance and an unfavorable temperature-pressure dependence, making them unsuitable for high-pressure and high-temperature applications such as hot steam environments, where they may experience non-reversible deformation or bursting.
Innovation Solution
A sensor assembly with a bowl-shaped membrane having a convex surface adjoining the sensor blade, designed to enhance pressure resistance and temperature dependence, while maintaining high sensitivity to pressure fluctuations, is developed. This includes various embodiments of membrane shapes and materials, such as stainless steel or nickel-based alloys, to ensure durability and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a flat membrane with high diameter-to-thickness ratio is used to achieve high measuring sensitivity, then the sensitivity to pressure fluctuations is improved, but the pressure resistance and mechanical stability deteriorate
Solution Approach 1:
The patent applies curvature to the membrane by forming it as a bowl-shaped pre-stressed membrane with a convex outer side. This curvature provides mechanical strength and pressure resistance while maintaining the thin profile needed for sensitivity. The pre-stressed state of the curved membrane allows it to withstand high pressures without compromising its ability to detect pressure fluctuations.
Solution Approach 2:
The patent changes the geometric parameters of the membrane by introducing a specific curvature radius and thickness profile. The membrane has a controlled thickness variation where the thinnest point is at least 0.5 mm away from the outer edge, creating an optimized balance between sensitivity (requiring thin regions) and strength (requiring adequate material distribution).
2Measurement precision
If the membrane thickness is reduced to increase measuring sensitivity, then the sensitivity is improved, but the mechanical stability and resistance to vibrations deteriorate
Solution Approach 1:
The bowl-shaped curvature of the membrane provides structural rigidity that compensates for the reduced thickness. The curved geometry distributes stresses more effectively than a flat membrane would, maintaining mechanical stability even with minimal thickness in the sensing region.
Solution Approach 2:
The membrane exhibits non-uniform thickness distribution with the thinnest region located at least 0.5 mm from the outer edge. This local quality variation optimizes the sensing region for maximum sensitivity while ensuring that edge regions have sufficient thickness for mechanical stability and proper sealing.
3Measurement precision
If a thin membrane is used to achieve high sensitivity, then the sensitivity is improved, but the resistance to pipeline vibrations and external forces deteriorates
Solution Approach 1:
The pre-stressed bowl shape of the membrane creates a structurally robust configuration that resists external vibrations and forces. The curvature provides inherent stiffness that protects the thin sensing region from damage while allowing it to remain responsive to pressure fluctuations.
Solution Approach 2:
The membrane is pre-stressed during manufacturing to establish a bowl shape before installation. This preliminary action of pre-stressing ensures that the membrane starts in a mechanically optimized state, ready to withstand vibrations and external forces during operation while maintaining sensitivity.
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 significantly improves the nominal pressure resistance and temperature dependence of the sensor assembly, allowing its use in extreme conditions above 140 bar and 400°C without compromising sensitivity, and can be manufactured with similar materials and processes as conventional systems, maintaining cost-effectiveness.
Implementation Method 1
a bowl shaped, namely at least sectionally dished, membrane (111) with a curved, first surface (111+) and an oppositely lying, second surface (111#)... at least one region of the first surface (111+) adjoining the sensor blade (112) is convex
Implementation Method 2
a sensor blade (112) extending from the first surface (111+) of the membrane (111)... adapted to register pressure fluctuations in the Kármán vortex street, namely to convert such into movements of the membrane (111) corresponding to the pressure fluctuations
Data Source
AI summary
The sensor assembly comprises: a bowl shaped, namely at least sectionally dished, membrane, with a curved surface and an oppositely lying surface; and a sensor blade extending from curved surface of the membrane. The membrane is so formed that at least one region of the curved surface adjoining the sensor blade is convex. A sensor formed by means of such a sensor assembly and by means of a transducer element coupled therewith and serving for generating a sensor signal representing movements of the sensor blade changing as a function of time and/or deformations of the membrane changing as a function of time, or a measuring system formed by means of the sensor and a measuring electronics connected thereto, can be used for registering pressure fluctuations in a flowing fluid, such as, for instance, a 400 C hot steam, for instance, in order to measure a flow parameter of the fluid.