Open GWR Probe Structure for Viscous Interface Measurement
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Solution Overview
Problem
Guided wave radar (GWR) probes face difficulties in accurately measuring fluid interfaces and levels in applications with viscous fluids, particularly when thick emulsion layers are present, due to gradual dielectric property changes and the tendency for build-up, which affects measurement accuracy and probe functionality.
Innovation Solution
The design features a probe with an open configuration using multiple ground rods instead of a traditional coaxial tube, equipped with spray nozzles for cleaning and an electrical cable for bottom-up measurement, allowing for improved detection of fluid interfaces and reducing build-up, while maintaining signal penetration and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional coaxial probe is used for GWR measurement, then the probe structure is simple and easy to manufacture, but build-up occurs between the inner conductor and outer tube leading to measurement errors and reduced functionality
Solution Approach 1:
The patent divides the traditional coaxial outer tube into multiple separate ground rods (typically three) arranged radially around the center rod. This segmentation eliminates the enclosed space where build-up occurs in conventional probes, while still providing the necessary ground reference for GWR measurements. The ground rods are spaced angularly (e.g., 120 degrees apart) to maintain electrical grounding functionality without creating a closed cavity susceptible to viscous fluid accumulation.
Solution Approach 2:
The patent extracts and removes the outer coaxial tube from the probe design, retaining only the essential ground function through separate ground rods. This extraction eliminates the harmful enclosed space where build-up occurs, while the ground rods continue to provide the necessary reference potential for radar signal transmission and reception.
2Reliability
If a coaxial probe with outer tube is used, then the probe provides good signal shielding, but the enclosed space promotes build-up of viscous fluids
Solution Approach 1:
The outer coaxial tube is segmented into multiple discrete ground rods arranged radially around the center rod. This segmentation maintains the grounding function necessary for signal transmission while eliminating the enclosed space that promotes build-up in traditional coaxial probes.
Solution Approach 2:
The patent transitions from a two-dimensional coaxial geometry (inner conductor surrounded by outer tube) to a three-dimensional radial arrangement of ground rods around the center rod. This dimensional change opens up the previously enclosed space, preventing build-up while maintaining grounding functionality through the radial distribution of ground rods.
3Reliability
If spray nozzles and flushing ports are added to the probe, then build-up is reduced through cleaning, but the probe structure becomes more complex
Solution Approach 1:
The patent incorporates spray nozzles and flushing ports that enable preventive cleaning of the probe surface before build-up significantly impacts measurements. The nozzles are positioned to spray cleaning fluid onto the center rod and ground rods, while flushing ports allow fluid to flow through and remove accumulated material, maintaining measurement accuracy proactively rather than reactively.
Solution Approach 2:
The probe incorporates self-cleaning capabilities through integrated spray nozzles and flushing ports that can be activated during operation. The system uses process fluid or cleaning agents to automatically remove build-up from the probe surfaces, reducing the need for manual intervention and maintaining measurement reliability without requiring complex external cleaning systems.
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 configuration enhances the detection of fluid interfaces and levels in viscous fluids by minimizing build-up and improving signal transmission, leading to more accurate measurements and reduced errors in multi-layered fluid applications.
Implementation Method 1
The GWR instrument measures the time of flight of the electrical signal to, and back from, this reflecting point, being the liquid surface, to find the liquid level.
Implementation Method 2
When the GWR signal encounters any impedance discontinuity in the transmission line part of the signal is reflected back toward the source in accordance with theory based on Maxwell's laws.
Implementation Method 3
An impedance discontinuity is created at the level surface due to the change in dielectric constant of the liquid versus air at this point.
Data Source
AI summary
There is disclosed a probe used with a measurement instrument including a pulse circuit for generating pulses. A coaxial connector is secured to the probe case so that the probe case is electrically connected to the ground shield. A center rod has a top end received in the probe case and to extend into a process liquid. The center rod is electrically connected to the center terminal for conducting the pulses. Ground rods are spaced around the center rod and are secured to the probe case. The probe provides an open configuration less susceptible to build-up between the center rod and the ground rods. One or more of the ground rods may by tubes, connected to a flushing port, with nozzles for cleaning the enter rod. Another ground rod may be tubular for carrying a conductor connected to a bottom of the center rod for bottom-up measurement.