Sensor Assembly with Protective Plate for High-Pressure Steam
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Solution Overview
Problem
Conventional sensor assemblies for detecting pressure fluctuations in flowing fluids, particularly in high-temperature and high-pressure steam applications, experience excessive measurement errors due to sensitivity to pressure surges and temperature fluctuations, leading to irreversible deformations that exceed their load limits.
Innovation Solution
A sensor assembly with a deformation body and a sensor flag, protected by a protective device featuring a spaced plate that forms a cavity and gap with the sensor vane, acting as a thermal and pressure low-pass filter to dampen fluctuations, allowing the fluid to fill the cavity and absorb pressure surges, thereby reducing sensitivity to these extreme conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the deformation body is made thin with a high diameter-to-thickness ratio (approximately 20:1) to achieve high measurement sensitivity, then the sensitivity to pressure fluctuations is improved, but the resistance to pressure surges and temperature fluctuations deteriorates, leading to irreversible deformations
Solution Approach 1:
The sensor assembly is divided into distinct functional zones: a measurement zone with the thin deformation body and sensor flag for high sensitivity, and a protection zone with the spaced plate and cavity for shock absorption. This segmentation allows each part to optimize its function without compromising the other.
Solution Approach 2:
The spaced plate positioned upstream of the deformation body creates a cavity that acts as a cushion before pressure surges reach the sensitive measurement elements. This pre-cushioning structure absorbs extreme pressure fluctuations before they can cause irreversible damage to the thin deformation body.
2Measurement precision
If the deformation body is exposed directly to the flowing fluid to detect pressure fluctuations, then the measurement capability is improved, but the exposure to extreme conditions (high pressure, high temperature) worsens, causing excessive deformations
Solution Approach 1:
The spaced plate acts as an intermediary element between the harsh fluid environment and the sensitive deformation body. It mediates the interaction by filtering out extreme pressure fluctuations while allowing the deformation body to remain exposed enough to detect meaningful pressure variations for measurement.
Solution Approach 2:
Different regions of the sensor assembly have different exposure qualities: the spaced plate and cavity region provides high protection against harmful factors, while the sensor flag and deformation body region maintains appropriate exposure for measurement. This local differentiation of quality allows simultaneous protection and measurement capability.
3Reliability
If a protective structure is added to shield the deformation body from pressure surges, then the reliability is improved, but the device complexity increases
Solution Approach 1:
The protective structure uses a thin spaced plate that forms a cavity, rather than a bulky rigid enclosure. This thin-film approach provides effective protection against pressure surges while minimizing added complexity and maintaining a relatively simple overall structure that can be manufactured efficiently.
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 reduces sensitivity to pressure surges and temperature fluctuations without compromising measurement sensitivity, ensuring high accuracy even in extreme conditions like superheated steam applications, and can be constructed similarly to conventional sensors using the same materials.
Implementation Method 1
the spaced, upstream plate and separated plate and deformation body leading to a cavity opening to the lumen, which acts as a thermal low-pass filter dampening temperature fluctuations
Implementation Method 2
the deformation body, the gap and the same fluid volume enclosed in the cavity also act together as a pressure low-pass filter dampening pressure surges
Implementation Method 3
the sensor vane, as a result of the pressure fluctuations, performs pendulum movements that elastically deform the deformation body in the detection direction
Implementation Method 4
the sensor also includes a corresponding converter element, which is formed, for example, by means of a capacitor mechanically coupled to the sensor assembly or integrated therein
Implementation Method 5
by means of a piezo stack serving as a piezoelectric converter to detect movements of the deformation body corresponding to pressure fluctuations
Data Source
Figure 1
Figure 2
Figure 3a~3d
AI summary
The sensor assembly (11) comprises a deformation body (111) having two surfaces (111+, 111#) which are opposite one another and an outer edge segment (111a), and a sensor vane (112) which extends from the surface (111+) to a distal end. The sensor assembly (11) also comprises a protective device (113) for protecting the deformation body (111) from pressure shocks against the surface (111+) thereof and/or for protecting the deformation body (111) from sudden changes in a temperature at the surface (111+) thereof. For this purpose, the protective device (113) has at least one plate (113a) which adjoins the edge segment (111a) of the deformation body (111) and extends radially inwards in the direction of the sensor vane in such a manner that a cavity (113') is formed between the plate and the deformation body, which cavity accommodates a region of the sensor vane which adjoins the surface (111+) of the deformation body (111) and is likewise remote from the distal end of the sensor vane, and that a gap (113'') is formed between the plate and the sensor vane. A sensor formed by means of such a sensor assembly and a transducer element (12) coupled thereto and used to generate a sensor signal representing temporally changing movements of the sensor vane and/or temporally changing deformations of the membrane, and a measurement system formed by means of said sensor and measuring electronics connected thereto can be used to detect pressure fluctuations in a flowing fluid, for example steam which is at least occasionally at 400°C and/or at least occasionally has a pressure of more than 140 bar, for example in order to measure a flow parameter of said fluid.