Optical Level Gauging for Non-Contact Cryogenic Tank Measurement
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Solution Overview
Problem
Current level gauging technologies for liquid tanks, particularly those handling cryogenic liquids, often require direct contact with the liquid, leading to issues such as electrical energy use inside the tank, potential fuel vaporization, inefficient leakage, and complex maintenance procedures.
Innovation Solution
An optical level gauge apparatus using a light source, sensor device, and light conducting device that conducts light rays to and from the tank volume without direct contact, employing pattern arrangements to reflect or absorb light and determine liquid levels based on image data processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If electrical sensors are used for level measurement, then measurement precision is improved, but safety risks and maintenance complexity increase due to electrical energy requirements inside the tank
Solution Approach 1:
The patent replaces electrical sensing systems with an optical measurement system. A light source emits light through the tank wall, and optical sensors detect the light after it passes through the liquid medium. This substitution eliminates electrical components inside the tank, removing safety hazards associated with electrical energy in cryogenic environments while maintaining measurement precision through optical detection of liquid level based on light absorption or refraction differences.
Solution Approach 2:
The patent introduces an optical window or transparent section in the tank wall as an intermediary medium. This window allows light to pass through from the external environment into the tank interior, enabling optical sensors to measure liquid level without direct contact with the cryogenic liquid. The intermediary window isolates the measurement system from the harsh internal environment while facilitating accurate optical measurement.
2Measurement precision
If discrete level measuring points are used, then measurement coverage is improved, but device complexity increases due to multiple ports and cables required
Solution Approach 1:
The patent employs a single optical measurement system that can determine multiple liquid levels simultaneously by analyzing light transmission at different angles or wavelengths. Instead of requiring separate sensors for each measurement point, the optical system uses a light source and detector arrangement that can detect multiple interface levels (e.g., between different cryogenic liquids or between liquid and vapor) through a single optical access point, thereby reducing the number of ports and cables needed.
Solution Approach 2:
The patent transitions from one-dimensional discrete point measurements to two-dimensional or three-dimensional optical field measurement. By using an optical system that can detect light transmission across multiple angles or positions within the tank, the system obtains comprehensive level information from a single measurement location, effectively adding spatial dimensions to the measurement capability without requiring multiple physical access points.
3Measurement precision
If fiber optic sensors with heating are used, then level detection accuracy is improved, but energy loss increases due to heat dissipation and fuel vaporization
Solution Approach 1:
The patent replaces thermal-based sensing (heating) with optical-based sensing. Instead of using heated elements or fiber optics that rely on temperature differences to detect liquid level, the system uses light transmission properties. The light source emits optical energy that passes through the tank wall and liquid, and the optical sensors detect changes in light intensity or refraction angle based on liquid level position. This substitution eliminates the need for thermal energy input, preventing fuel vaporization and associated energy losses while maintaining measurement accuracy.
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
Enables non-contact, non-electrical liquid level measurement within cryogenic tanks, reducing maintenance complexity and safety risks while maintaining high accuracy and allowing external installation and maintenance.
Implementation Method 1
a light conducting device configured to be optically coupled to the light source, the sensor device, and the tank volume, wherein, when optically coupled to the light source, the sensor device, and the tank volume, the light conducting device is capable of conducting outgoing light rays from the light source to the tank volume and incoming light rays, that were reflected or scattered at least once within the tank volume, from the tank volume to the sensor device
Implementation Method 2
The pattern arrangement is suitable to reflect the outgoing light rays, thereby generating the incoming light rays
Implementation Method 3
the pattern arrangement is configured to absorb a first wavelength emitted by the light source and configured to emit a second wavelength that is different from the first wavelength
Implementation Method 4
Many current solutions for level gauging require the sensing element in direct contact with the liquid inside the tank, sometimes even requiring the use of electrical energy inside the tank
Data Source
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AI summary
In order to improve liquid level gauging inside liquid tanks (22), especially cryogenic liquid tanks, the invention provides an apparatus and method for determining the liquid level, L. A light source emits outgoing light rays (34) that are back reflected or scattered by the tank wall (24) of the liquid tank (22). The back reflected or scattered incoming light rays (48) are received by a light conducting device (36), which conducts the incoming light rays (48) towards a sensor device (54). The sensor device (54) has optical sensors (56) that are coupled to the light conducting device (36) in such a manner that there is a one-two-one relationship between each optical sensor (56) and a specific tank wall portion (58). Due to the change in the amount of light that is received by the optical sensor (56) after the outgoing light rays (34) were refracted by the liquid surface (46), the liquid level determining device (60) is capable of determining the liquid level L.