Fluorescence Spectroscopy API Gravity Measurement
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Solution Overview
Problem
Current methods for determining the American Petroleum Institute (API) gravity of crude oils are not instantaneous, require sample preparation, and lack the capability for non-destructive, compact measurement.
Innovation Solution
The technique involves measuring fluorescence spectra of crude oils at two different laser angles-of-incidence, normalizing and subtracting the spectra, and calculating the areas-under-the-curve to correlate with API gravity, using a compact device that excites the oil with a UV laser and collects fluorescence emissions with a CCD spectrometer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If traditional methods are used to determine API gravity, then measurement accuracy can be maintained, but the process is not instantaneous and requires sample preparation
Solution Approach 1:
The patent replaces traditional mechanical measurement systems with laser-induced fluorescence spectroscopy. A laser excites the crude oil sample, causing it to emit fluorescence at specific wavelengths. The spectral characteristics of this fluorescence are directly correlated to API gravity, enabling instantaneous measurement without mechanical sample preparation or density-based measurement procedures.
Solution Approach 2:
The patent utilizes the fluorescence emission spectrum as a new parameter for determining API gravity. By measuring the intensity ratios of fluorescence at different wavelengths (e.g., 450nm/500nm), the system transforms the measurement parameter from density-based to spectroscopy-based, achieving rapid and preparation-free measurement.
2Volume of moving object
If a compact device is constructed using laser-based techniques, then device size is reduced, but measurement capability must be maintained
Solution Approach 1:
The patent merges multiple functions into a single compact device: the laser source, sample holder, fluorescence collection optics, and spectral detection system are integrated into one unit. This consolidation reduces the overall device volume while maintaining all necessary measurement capabilities through optimized optical path design and compact component arrangement.
Solution Approach 2:
The compact device is designed to be universally applicable to different crude oil samples. The laser-induced fluorescence system can measure various oil types by analyzing their unique spectral signatures, making the device multi-functional for different applications while maintaining a small form factor.
3Measurement precision
If fluorescence spectra are measured at multiple angles, then API gravity identification accuracy is improved, but device complexity increases
Solution Approach 1:
The patent introduces angular dimension to the fluorescence measurement by collecting spectra at multiple angles (e.g., 0°, 45°, 90° relative to the laser beam). This angular dimension provides additional independent parameters for characterizing the crude oil sample, improving API gravity identification accuracy through multi-angle spectral analysis.
Solution Approach 2:
The measurement process is segmented into multiple angular components, with each angle providing independent spectral information. The system separately measures and processes spectra from different angles, then combines these segmented measurements to achieve superior identification accuracy while managing device complexity through modular optical components.
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 method allows for almost instantaneous, non-destructive, and compact measurement of API gravity, distinguishing between different crude oil samples and providing accurate API gravity values with a high correlation coefficient (R2=0.997).
Implementation Method 1
Some fluids can fluoresce, that is, they give off light when stimulated by a certain wavelength of light from an external source. Different fluids are sensitive to different wavelengths of light, and different fluids fluoresce to different wavelengths of light when stimulated or excited.
Implementation Method 2
laser-induced fluorescence techniques... laser-based techniques can be used when constructing a compact device
Data Source
AI summary
Systems and methods include a fluorescence measurement apparatus. A single-wavelength light source generates an excitation light source. A sample holder holds a sample and includes a surface transparent to the excitation light source. Mounts attached to the single-wavelength light source(s) or the sample holder change an incident angle of the excitation light source on the surface. Optical components positioned in a path of a fluorescence emission emitted from the surface guide the fluorescence emission to a detector that obtains spectra from at least first and second angles-of-incidence. A device records spectra obtained by the detector from the first and second angles-of-incidence, normalizes and analyzes intensities of the spectra, subtracts a first spectrum corresponding to the first angle-of-incidence from a second spectrum corresponding to the second angle-of-incidence to obtain a difference, identifying a sample type of the sample based on an API gravity mapped to the difference.