Pipe Fluid Density Measurement via Vibration Spectrum Analysis
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Solution Overview
Problem
Existing density measurement systems for industrial processes are either invasive, costly, and hazardous due to potential leakage, or non-invasive methods like nuclear radiation-based densitometers are unpopular due to radioactive hazards and high costs.
Innovation Solution
A measurement system that uses a pair of confining elements to define a section of the pipe-fluid system, reducing surface vibration deformations and allowing for accurate prediction of vibration modes sensitive to fluid density, enabling non-invasive density measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If invasive density sensors (Coriolis or vibrating fork) are inserted into the process, then accurate density measurement is achieved, but installation time increases, process interruption is required, and safety hazards from potential leakage occur
Solution Approach 1:
The patent uses the pipe itself as an intermediary measurement medium. Instead of inserting a sensor into the fluid, the pipe wall acts as a mediator that transmits vibration information from the fluid to external sensors, enabling indirect measurement without breaking the process seal
Solution Approach 2:
The patent replaces the mechanical insertion of invasive sensors with a non-contact or external contact measurement system. Vibration sensors are placed on the external surface of the pipe, substituting the need for internal fluid-contacting mechanical components
2Measurement precision
If nuclear radiation-based densitometers are used for non-invasive measurement, then robust and accurate measurements are achieved under harsh conditions, but radioactive hazards and high cost make the equipment unpopular and limited in use
Solution Approach 1:
The patent employs inexpensive piezoelectric or piezoresistive sensors that can be easily replaced if needed, substituting the expensive and hazardous nuclear sources. These sensors provide sufficient measurement capability without the long-term radioactive hazards
Solution Approach 2:
The patent substitutes nuclear radiation-based measurement with mechanical vibration-based measurement. By exciting the pipe-fluid system mechanically and analyzing its resonant frequencies, the system achieves density measurement without radioactive materials
3Measurement precision
If the pipe section length is increased to improve vibration mode distinguishability, then frequency overlap with machinery vibrations is reduced, but the measurement system becomes more sensitive to boundary condition variations and installation complexity increases
Solution Approach 1:
The patent makes the measurement system adaptable to different pipe lengths and boundary conditions through dynamic selection of vibration modes. The system identifies suitable resonant modes based on the specific installation geometry, allowing flexible deployment without fixed installation requirements
Solution Approach 2:
The patent changes the measurement approach by selecting different vibration modes (characterized by different mode numbers and frequency ranges) depending on the pipe length and boundary conditions. This parameter adaptation allows the system to maintain measurement accuracy across various installation scenarios
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 allows for simple, robust, and cost-effective determination of fluid density in process pipes based on vibration spectrum analysis, reducing installation costs and safety hazards while providing accurate measurements.
Implementation Method 1
an excitation system, configured to generate a mechanical vibration spectrum on a surface of the pipe-fluid system
Implementation Method 2
a vibration measurement device configured to be mechanically coupled to an outer surface of the pipe-fluid system, and configured to provide a mechanical vibration spectrum of the pipe-fluid system
Implementation Method 3
a pair of confining elements configured to decrease surface vibration deformations at each end of the pipe-fluid system
Data Source
Figure 1~2
Figure 3~4
Figure 5~7b
AI summary
A measurement system for determining a physical parameter of a pipe-fluid system, including: a pair of confining elements configured to decrease surface vibration deformations at each end of the pipe-fluid system; an excitation system, configured to generate a mechanical vibration spectrum at a surface of the pipe-fluid system; and a vibration measurement device configured to be mechanically coupled to an outer surface of the pipe-fluid system, and configured to provide a mechanical vibration spectrum of the pipe-fluid system.