Radar Level Gauge Dual-Channel Density Measurement
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Solution Overview
Problem
Current radar level gauge systems face challenges in accurately determining the density distribution of liquid phase products in LNG tanks, particularly in preventing rollover incidents by effectively measuring the interface between liquid and vapor phases, due to variations in density across different levels.
Innovation Solution
The system employs two independent measurement channels with distinct electromagnetic signal properties, sharing the same antenna and tubular waveguide, where signal interacting structures are strategically placed to selectively interact with one channel's signals, allowing for precise determination of the interface level and density distribution by using different polarizations and propagation modes, and processing circuitry to analyze reflection signals for accurate density calculations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single measurement channel is used to determine both interface level and density, then device complexity is reduced, but measurement precision deteriorates due to inability to selectively measure different parameters
Solution Approach 1:
The measurement system is divided into two independent measurement channels: a first measurement channel configured to determine the interface level by measuring reflection signals from the liquid-vapor interface, and a second measurement channel configured to determine density by measuring reflection signals from the liquid product. Each channel uses specific signal properties (frequency, polarization, or waveform) to selectively interact with different targets, enabling precise separate measurement of level and density without cross-interference.
2Measurement precision
If density measurement structures are added to the waveguide, then density distribution determination is improved, but reliability of interface level measurement deteriorates due to additional signal reflections
Solution Approach 1:
Signal interacting structures (such as reflectors or resonators) are placed at specific locations along the waveguide where they selectively interact with the second measurement channel's signals for density measurement. These structures are positioned and configured to minimize interference with the first measurement channel's interface level detection, allowing localized density measurement without compromising overall system reliability.
3Measurement precision
If electromagnetic signals with different properties are used for level and density measurement, then measurement precision is improved, but device complexity increases due to multiple transceivers and signal processing requirements
Solution Approach 1:
A single antenna structure is designed to support multiple measurement functions by transmitting and receiving electromagnetic signals with different properties (frequencies, polarizations, or waveforms). The antenna system is configured to radiate signals for both interface level detection and density measurement, eliminating the need for separate antennas and reducing overall device complexity while maintaining measurement precision through multi-functional signal handling.
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
This approach enables a more precise and reliable measurement of the interface level and density distribution, reducing measurement errors and improving safety by preventing rollover incidents in LNG tanks.
Implementation Method 1
an electromagnetic reflection signal resulting from reflection of the transmit signal at the surface is propagated back towards to the transceiver
Implementation Method 2
the relationship between a dielectric constant and a density of the medium is known
Data Source
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AI summary
A radar level gauge system comprising a first transceiver; a second transceiver; an antenna arranged to radiate a first transmit signal generated by the first transceiver and a second transmit signal generated by the second transceiver, and to receive a first reflection signal and a second reflection signal; a tubular waveguide to guide the transmit signals towards the interface, and to guide the reflection signals back towards the antenna; a plurality of signal interacting structures arranged at different levels along a the tubular waveguide, to selectively interact with the second transmit signal to contribute to the second reflection signal; and processing circuitry to determine a level of the interface between liquid phase product and vapor phase product based on a relation between the first transmit signal and the first reflection signal, and a density distribution based on a relation between the second transmit signal and the second reflection signal.