Monitoring of CO flare emissions using open-path Fourier transform infrared technology

摘要

A pilot study was performed in order to gather data to determine the efficiencies of two nearby CO flares. Each flare stack was about 150 feet high with the thermal rise of the flare raising the resulting plume to about 200 feet. Since there are no routinely accepted methods for determining flare emissions, especially for such high flares, the pilot study was designed to collect the appropriate data using open-path Fourier Transform Infrared (OP-FTIR) technology. There were a number of challenges both in physically setting up the equipment and in evaluating the resulting spectra: (1) The retroreflector needed to be hung on a 300 foot crane in order to have the plume centerlines near the center of the beam. (2) The positions of the crane and main OP-FTIR unit had to be determined in relation to availability of space at the appropriate downwind distances since this was an operating facility. (3) The tracer gases (SF$-6$/ and CF$-4$/) needed to be released at rates to provide sufficiently high downwind concentrations. (4) Sufficient upwind data needed to be collected to be able to subtract the background CO and CO$-2$/ values with enough accuracy to provide data for efficiency calculation. (5) The spectra collected for the beam paths (approximately 300 to 350 m from main unit to retroreflector angled from ground level to approximately 100 meters) traversed a wide range of temperatures and to a certain degree pressures which would affect the determination of the plume concentrations. This paper presents a discussion of these challenges and the degrees to which they were met. Suggestions for improving such studies is also included.