# A Three-Wavelength Optical Sensor for Measuring the Multi-Particle-Size Channel Mass Concentration of Thermal Power Plant Emissions

## TL;DR

A new three-wavelength optical sensor measures both particle mass concentration and size distribution in thermal power plant emissions for better pollution assessment.

## Contribution

A novel three-wavelength optical sensor is introduced to measure multi-particle-size channel mass concentration and PSD in real-world settings.

## Key findings

- The sensor accurately measures mass concentration of PM10, PM2.5, and PM1.
- The prototype determines mean diameter and standard deviation of particle size distributions.
- Results show the sensor can comprehensively estimate thermal power plant emissions.

## Abstract

Emissions from thermal power plants have always been the central consideration for environmental protection. Existing optical sensors in thermal power plants usually measure the total mass concentration of the particulate matter (PM) by a single-wavelength laser, bearing intrinsic errors owing to the variation in particle size distribution (PSD). However, the total mass concentration alone cannot characterize all the harmful effects of the air pollution caused by the power plant. Therefore, it is necessary to measure the mass concentration and PSD simultaneously, based on which we can obtain multi-particle-size channel mass concentration. To achieve this, we designed an optical sensor based on the three-wavelength technique and tested its performance in a practical environment. Results showed that the prototype cannot only correctly measure the mass concentration of the emitted PM but also determine the mean diameter and standard deviation of the PSDs. Hence, the mass concentrations of PM10, PM2.5, and PM1 are calculated, and the air pollutants emission by a thermal power plant can be estimated comprehensively.