Emissions of Hazardous Air Pollutants and Ozone Precursors from a Natural Gas-Fired Burner

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TTc Presented at the Joint Meeting of the Japanese and American Flame Research Committees October 11-15, 1998, Maui, Hawaii EMISSIONS OF HAZARDOUS AIR POLLUTANTS AND OZONE PRECURSORS FROM A NATURAL GAS-FIRED BURNER by T. N. Demayo G. S. Samuelsen UCI Combustion Laboratory, University of California, Irvine C A, USA, 92697-3550 Tel: [phone] Fax: [phone] ABSTRACT Due to heightened environmental concerns about air quality, urban areas around the world are shifting to the use of natural gas for continuous stationary combustion systems. However, U S E P A regulations concerning hazardous air pollutants (HAPs) and ozone precursors (OPs) may pose challenges in the design and operation of advanced gas-fired combustion systems. As natural gas systems switch to lean, premixed operation to reduce N O x formation and maintain high combustion efficiency, the emissions of H A P s and O P s - specifically of volatile organic compounds ( V O C s ) - may potentially increase. A study was conducted to investigate the effect of low-NOx operating conditions on V O C emissions for a scaled, generic, low-NOx, natural gas-fired burner. The exhaust samples were analyzed for Ci - Cio aliphatic, aromatic, and carbonylic hydrocarbons using USEPA-sanctioned methods. Most V O C s were emitted in relatively low concentrations (< 100 ppbv). However, certain very lean and high air velocity conditions generated relatively high total V O C levels (2 - 118 ppmC). To address concerns regarding the release of V O C s from stationary combustion systems, a performance function based on N O x , C O , and V O C emissions was developed to identify an optimal set of conditions where all pollutant emissions are minimized. If natural gas-fired systems operate at these optimal conditions, a significant regulatory concern with respect to V O C emissions can be mitigated. Achieving and maintaining this level of performance may require active control and the use of indicator species. The data show a positive correlation between VOCs, C O , and total hydrocarbons (THCs), suggesting that C O and T H C s could potentially serve as surrogates for V O C emissions under lean burn conditions.