PNNL

Abstract

Pyrolysis is the first step in a series of chemical and physical processes that produce flammable organic gases from wildland fuels that can result in a wildland fire. We report results using a new time-resolved Fourier transform infrared method that correlates the measured FTIR spectrum to an infrared thermal image sequence enabling identification and quantification of gases within different phases of the fire process. The flame from burning fuel beds composed of pine needles (Pinus palustris) and mixtures of sparkleberry, fetterbush and inkberry plants was the natural heat source for pyrolysis. Extractive gas samples were analyzed and identified in both static and dynamic modes synchronized to thermal infrared imaging: A total of 29 gases were identified including small alkanes, alkenes, aldehydes, nitrogen compounds and aromatics, most previously measured by FTIR in wildland fires. This study presents one of the first identifications of phenol associated with both pre-combustion and combustion phases, using ca. 1 Hz resolution. Preliminary results indicate ~2.5x greater phenol emission from sparkleberry and inkberry compared to fetterbush, with differing temporal profiles.