Reconstruction of Smoke Plume Concentration Peaks Based on Modified MAX-DOAS Tomography

Abstract

Optical tomography system based on modified simultaneous iterative reconstruction technique is designed to real-time monitor spatial distribution and diffusion process of smoke plume in a power plant. Concentration profiles, rather than just a point value, of smoke plume concentrations are the goal of this method, and the tomography algorithm is analyzed. According to incomplete projection data in the process of reconstruction and exiting noise interference, the modified simultaneous iterative reconstruction technique (SIRT) is adopted to extract the information of the trace gas concentration by a fan beam scanning and is compared to the conventional SIRT. Three evaluation indexes show that the reconstruction effect is the best by choosing proper relaxation factor, which reduces the index d to 0.044 from 0.435 and reduces the index r to 0.044 from 0.376 for 5500 iterations. Hence, the modified algorithm performs better in estimating the shape of the plume, this method is used to process the measured spectra in field campaign, the reconstruction results and the measured data are basically consistent, which is further confirmed by the experimental results.

Vertical Distribution Mapping for Methane Fugitive Emissions Using Laser Path-Integral Sensing in Non-Cooperative Open Paths

“…Moreover, the gas-diffusion region can be discretized into a uniform grid of square cells. It is assumed that the methane concentration in each cell is constant [ 39 ], so the TDLAS measurement alone for the single laser beam path is expressed as follows: where y i is the path-integral concentration measured by the laser beam i , N is the number of square cells of the uniform grid, l i , j is the absorption path length of the laser beam i in the j -th cell and x j is the averaged methane concentration in cell j .…”

“…Moreover, the gas-diffusion region can be discretized into a uniform grid of square cells. It is assumed that the methane concentration in each cell is constan [39], so the TDLAS measurement alone for the single laser beam path is expressed as fol lows:…”

Vertical profile of aerosol extinction based on the measurement of O4of multi-elevation angles with MAX-DOAS*

“…[3] In recent years, differential optical absorption spectroscopy (DOAS) is used in the field of atmospheric environmental monitoring. [4] The multi-axis DOAS (MAX-DOAS) composed of zenith direction and low observation elevation greatly improves the observation sensitivity of the tropospheric atmosphere. Trace gas profiles in the troposphere can be obtained by combining with the atmospheric radiation transfer model.…”