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Show RESULTS AND DISCUSSION VOC Emission Profiles A comparison of the VOC profile of the natural gas supply with the VOCs measured from the burner reveals that, depending on the test case, the combustion process results in varying degrees of destruction of the target VOCs and in the generation of new compounds. In general, the VOC emissions included mostly • methane, • lighter (d - d) alkanes, alkenes and alkynes, • trace amounts of aromatics (benzene and toluene), and • aldehydes (mostly formaldehyde with trace levels of acetaldehyde). The significant presence of alkanes (d - d) suggests the presence of unburned fuel The alkenes (especially ethylene, propylene, and isobutylene) and alkynes (especially acetylene), none of which were detected in the natural gas supply, may result from the pyrolytic dehydrogenation of the alkanes. As shown in Fig. 6, the concentrations of most of the identified VOCs, separated into non-polar hydrocarbons and aldehydes, were low (<100 ppbv). However, cases 4 (high V and S') and 5 (high V") generated high levels (0.2 - 50 ppmv) of d and d aliphatics and formaldehyde (200-350 ppbv). Cases 2 and 5 produced a large number of different VOCs, including aromatics and aliphatics up to Cg. Methane emissions ranged from 0-70 ppm for cases 1-4 and 940 ppm for case 5. Fig. 6 also shows concentrations of THCs, measured by a flame ionization detector, and of CO, measured by a non-dispersive infrared analyzer. 10 i |