Self-Calibrating Optical Liquid Level Sensor Using Backscattering
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Solution Overview
Problem
Existing contactless liquid level measurement technologies, such as electromechanical devices and ultrasonic radar sensors, face challenges in precision and reliability, especially in degraded conditions like high humidity and extreme environments, and require calibration or external clocks, making them unsuitable for deep storage tanks like nuclear fuel pools.
Innovation Solution
An optical device with a single-channel optical unit and double-core optical fibre for emitting and receiving signals, allowing backscattering and eliminating the need for external clocks or calibration, enabling precise and reliable measurements without prior setup in harsh conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If electromechanical devices with moveable floats are used for continuous level measurement, then continuous measurement capability is achieved, but mounting difficulty and limited measurement range (less than 10 metres) occur in existing deep fuel pools
Solution Approach 1:
The patent replaces the mechanical electromechanical float system with an optical measurement system that uses optical fibres and light propagation to measure liquid levels. This substitution eliminates the need for mechanical components that require mounting in the pool bottom, allowing contactless measurement from above the liquid surface while maintaining continuous measurement capability.
2Ease of operation
If ultrasonic radar sensors are used for contactless level measurement, then mounting ease is improved, but measurement precision deteriorates in degraded conditions with high water vapour content
Solution Approach 1:
The patent changes the physical parameter used for measurement from ultrasonic waves to optical signals. Optical signals are less sensitive to water vapour and humidity compared to ultrasonic waves, allowing precise level measurement in degraded conditions while maintaining the contactless measurement advantage and ease of mounting.
3Object-affected harmful factors
If radar sensors with electrical/electronic components are positioned above fuel pools, then contactless measurement is achieved, but sensitivity to earthquakes, irradiations, high temperatures and pressures increases
Solution Approach 1:
The patent replaces electrical/electronic radar components with an optical system that uses light propagation through optical fibres. This substitution makes the measurement system more resistant to electromagnetic interference, earthquakes, and extreme environmental conditions while maintaining contactless measurement capability above the fuel pool.
4Measurement precision
If optical sensors with separate emission and reception channels are used, then measurement capability is achieved, but device complexity and calibration requirements increase
Solution Approach 1:
The patent merges the emission and reception functions into a single optical channel by using backscattering from the liquid surface. The optical fibre both transmits the measurement signal to the liquid surface and receives the backscattered signal, eliminating the need for separate emission and reception channels and reducing device complexity while maintaining measurement precision.
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 optical device provides precise, repeatable, and robust liquid level measurements in deep storage tanks and harsh environments, such as nuclear fuel pools, with improved signal recovery and reduced sensitivity to vibrations and humidity.
Implementation Method 1
said optical unit being connected to said electronic control unit through an optical fibre capable of transmitting said optical signal emitted by said electronic control unit
Implementation Method 2
said optical fibre having two optical cores that juxtapose each other such that at least a part of the optical signal emitted in said first optical core of said optical fibre is backscattered in said second optical core
Implementation Method 3
A part of the optical beam is reflected towards the optical unit
Implementation Method 4
The distance between the surface of the fluid and the optical unit is obtained by measuring the time taken by the pulses to go back and forth by means of an electronic clock
Data Source
AI summary
An optical device for the contactless measurement of a liquid level contained in a storage device by an optical signal, the optical device including an optical unit fixedly positioned above the storage device and an electronic control unit capable of emitting an optical signal, dissociated from the optical unit and positioned at a distance from the optical unit. The optical unit includes a single channel for the emission and the reception of the optical signal. The optical unit is connected to the electronic control unit through an optical fibre capable of transmitting the optical signal emitted by the electronic control unit and an optical signal reflected by the liquid. The optical fibre has first and second optical cores that juxtapose each other such that at least a part of the optical signal emitted in the first optical core of the optical fibre is backscattered in the second optical core.