Microwave Resonator Density Measurement for Contaminated Media
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Solution Overview
Problem
Existing methods for determining the density of a medium in a tank are prone to errors due to contamination and are not robust, especially in applications involving liquefied gases like LNG and LPG, where mechanical resonators are sensitive to impurities and may provide erroneous readings.
Innovation Solution
A system using a microwave resonator configured to have a resonance frequency dependent on the dielectric constant of the surrounding medium, allowing for accurate density determination through the measurement of resonance frequency, with a high Q-value and low resistive losses to distinguish the resonance signal from other reflections, and a transceiver capable of generating and receiving microwave signals over a specific frequency range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If mechanical resonators are used to determine density, then density measurement capability is provided, but measurement reliability deteriorates due to sensitivity to contamination
Solution Approach 1:
The patent replaces mechanical resonators with electromagnetic resonators (microwave resonators). The electromagnetic resonator determines density through its resonance frequency, which depends on the dielectric constant of the surrounding medium. This substitution eliminates the contamination sensitivity issue of mechanical resonators while maintaining density measurement capability, as electromagnetic fields are not affected by contaminant mass attachment in the same way mechanical structures are.
2Measurement precision
If mechanical resonators are used in harsh conditions, then density measurement is possible, but device robustness deteriorates due to sensitivity to impurities
Solution Approach 1:
The patent substitutes mechanical resonators with electromagnetic resonators that operate in the microwave frequency range. The electromagnetic resonator's resonance frequency is determined by the dielectric constant of the medium, making it insensitive to contaminant impurities. This provides robust density measurement capability in harsh conditions involving liquefied gases like LNG and LPG where mechanical resonators would be affected by contamination.
3Measurement precision
If a frequency range is used for measurement, then measurement capability is provided, but signal distinguishability worsens due to interference from other reflections
Solution Approach 1:
The patent employs multiple electromagnetic resonators, each with a distinct resonance frequency within the microwave frequency range. By assigning different resonance frequencies to different resonators, the system can distinguish between signals from different locations (different heights in the tank). This local differentiation of frequency characteristics allows the system to identify and process only the relevant resonance signals while filtering out other reflections and interference.
Solution Approach 2:
The patent utilizes the resonance frequency parameter of electromagnetic resonators, which varies based on the dielectric constant of the surrounding medium. By measuring changes in resonance frequency, the system can determine density variations at different heights. The high Q-value of the resonators ensures that the resonance signals are sharp and well-defined, making them distinguishable from other reflections even in the presence of a broad frequency range.
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 system provides robust and accurate density measurements by minimizing interference and maintaining accuracy even in the presence of contaminants, reducing maintenance needs and improving measurement reliability in harsh conditions.
Implementation Method 1
The microwave resonator has a resonance frequency which has a first bandwidth, the first bandwidth being smaller than and within the frequency range. When the electromagnetic signal is guided by the waveguide towards a surface of the product, a portion of the signal is reflected by the microwave resonator in the frequency domain corresponding to the first bandwidth when a frequency of the electromagnetic signal corresponds to the resonance frequency of the microwave resonator.
Implementation Method 2
the resonance frequency of the microwave resonator being dependent on a dielectric constant of a medium surrounding the microwave resonator according to a known relationship
Data Source
Figure 1~2
Figure 3A~3B
Figure 3C~3E
AI summary
A system and method for determining a density of a non-conducting medium in a tank is disclosed where the relationship between a dielectric constant and a density of the medium is known. The system comprises a transceiver, and a waveguide, the waveguide extends towards and into the medium. The system further comprises a first microwave resonator located along the waveguide. The first microwave resonator has a resonance frequency, which depends on a dielectric constant of a medium surrounding the resonator according to a known relationship, and is arranged to reflect a portion in the frequency domain of a signal being guided along the wave guide. The system further comprises processing circuitry connected to the transceiver and configured to determine the resonance frequency based on a received reflected signal, and to determine a density of the medium at the location of the first microwave resonator based on the resonance frequency.