Optical Analysis Device for Particulate Matter
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Solution Overview
Problem
Current methods for determining particulate matter concentrations, such as 90° scattered light technology and laser diffraction, face challenges in accurately measuring small dust mass concentrations and providing size-resolved information, leading to increased costs and inaccuracies, especially with stricter emission limits and low particulate matter levels.
Innovation Solution
An optical analysis device using at least three light sources with different wavelengths, combined on a common optical path, with detectors positioned at specific scattering angles to detect scattered light intensities, allowing for the determination of particulate matter size distribution and mass percentages, including PM1, PM2.5, and PM10, through wavelength-selective detection and calibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If 90° scattered light technology is used to measure single particles, then particle size can be determined, but the measurement becomes laborious and requires carrier gas which may falsify results
Solution Approach 1:
The patent replaces the mechanical/single-particle measurement approach with an optical field-based method using laser diffraction. Instead of measuring individual particles through complex mechanical introduction systems requiring carrier gas, the invention uses laser light diffraction patterns to simultaneously characterize entire particle populations, eliminating the need for laborious single-particle handling and carrier gas systems.
2Loss of information
If laser diffraction technology with multiple detectors is used, then comprehensive particle size information can be obtained, but the device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the detection task across multiple detectors positioned at different scattering angles (front, side, and back scattering directions). Each detector captures specific angular information, and the control unit integrates these segmented measurements to reconstruct complete particle size distribution data. This segmentation enables comprehensive size-resolved information while maintaining manageable system complexity through modular detector arrangement.
Solution Approach 2:
The patent creates a universal measurement system where the combination of multiple detectors at different angles serves multiple functions simultaneously: determining particle size distribution, calculating mass concentrations for different PM fractions (PM1, PM2.5, PM10), and providing size-resolved information. This multi-functional approach consolidates what would otherwise require separate measurement systems into a single integrated device.
3Measurement precision
If automatic measurement systems are calibrated with gravimetric reference method, then accurate dust mass concentrations can be obtained, but calibration becomes increasingly difficult with small dust mass concentrations
Solution Approach 1:
The patent overcomes calibration difficulties by changing the measurement parameters from direct gravimetric measurement to optical diffraction pattern analysis. By measuring light scattering intensities at multiple angles and wavelengths, the system determines particle size distribution and mass concentration through optical parameters rather than requiring gravimetric calibration. This parameter transformation enables accurate measurement of small dust concentrations without the calibration challenges inherent in gravimetric methods.
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 device enables continuous measurement of particulate matter mass percentages and total dust concentration with improved detection of smaller particles, overcoming the limitations of existing technologies by using multiple detectors in forward, side, and back-scattering directions, and providing absolute particle size distribution in physical units.
Implementation Method 1
the transmitted light is incident on the gas to be measured and is scattered at the particulate matter
Data Source
AI summary
An optical analysis device for determining particulate matter includes three light sources having different wavelengths, an apparatus for combining the three transmitted light beams on a common optical path, a measurement volume, an optical axis in the forward scattering direction defines the scattering angle 0°, a light absorption apparatus at 0° that absorbs unscattered light, and six detectors which are arranged at different specified angles which are as close as possible to 0° directly next to the light absorption apparatus, at a second scattering angle between 7° and 40°, at a third scattering angle between 41° and 70°, at a fourth scattering angle between 71° and 115°, at a fifth scattering angle between 116° and 145°, at a sixth scattering angle between 146° and 180°. A control and evaluation unit controls the light sources such that the scattered light is detected in a wavelength selective manner by the detectors.