A generalized sky-LOSA method to quantify soot/black carbon emission rates in atmospheric plumes of gas flares

摘要

A new generalized theory governing sky-LOSA measurements (line-of-sight attenuation measurements of sky-light) of soot mass flux in atmospheric plumes has been developed which enables accurate measurements in the presence of in-scattered light from the sky and sun. The new approach is quantitatively tested using field measurement data collected for a gas flare at a turbocompressor station in Mexico. Although the soot plume of the tested flare was on the threshold of visible to the naked eye, the sensitivity of the current hardware was more than sufficient to resolve the soot mass emission rate of 0.067 g/s, with a quantified 95% confidence interval of 0.050 to 0.090 g/s. Results of a Monte Carlo simulation showed that soot optical property uncertainty was the major contributor to the overall measurement uncertainty. By contrast, correction of in-scattering via the generalized theory was a comparatively minor contributor, and was specifically insensitive to assumptions about the sky polarization state and intensity distribution. Given the prevalence of flaring and its implication as a potentially critical source of black carbon emissions, sky-LOSA is an essential new technology to directly quantify the impact of these globally distributed sources, for which comparable technologies do not exist.