Open path LII diagnostic for the determination of PM emissions from flares. Year 2 report to Natural Resources Canada

A novel technique for quantifying soot (PM) emissions in flare plumes was investigated. The proposed technique is based on auto-compensating laser induced incandescence (AC-LII) configured for remote measurement of LII emission from a soot plume. The theory of AC-LII was presented and the literature on retro-LII was reviewed. The key features and targets of a new remote AC-LII were then defined and implemented. The system was tested on a plume of known concentration at a moderate distance. The sensitivity of the remote AC-LII system was ample to measure the LII emission from the plume; and the preliminary results overpredicted the plume concentration by 70%. Further work is needed to verify the operating conditions of the burner and the absolute light intensity calibration of the remote AC-LII system in order to improve the measurement accuracy. An additional piece added to the inverted flame will allow the creation of a soot aerosol of variable length well suited for testing of the remote AC-LII system at distance more representative of a field measurement. An analysis of the present sensitivity of the system and an extrapolation of this sensitivity to a field setting indicated that the remote AC-LII system would have a target sensitivity of 0.35 to 5 ?g/m3 in a 2 m diameter plume at a distance of 30 m, depending on the size and focal length of the telescope used for the LII emission collection. With a wind speed of 4 m/s, this would translate to a carbon emission rate sensitivity of 5 to 65 ?g/s. However, these numbers are estimates only and must be verified with field distance trials. Significant challenges remain in the further development of this novel technology for remote quantification of PM emissions and complete success of this method is by no means certain. Nevertheless, a potentially viable approach for quantifying PM emissions from unconfined sources such as plumes and industrial flares has been identified and demonstrated. It is recommended that the research continue to the next critical phase of demonstration of the diagnostic at distances relevant to an industrial flare plume measurement.Peer reviewed: NoNRC publication: Ye